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Mixing pulp suspensions Bennington, Chad Patrick Joseph 1988

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M I X I N G P U L P S U S P E N S I O N S By Chad Patrick Joseph Bennington B.Sc. The University of British Columbia, 1979 M.A.Sc. The University of British Columbia, 1983 A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY in THE FACULTY OF GRADUATE STUDIES DEPARTMENT OF CHEMICAL ENGINEERING We accept this thesis as conforming to the required standard THE UNIVERSITY OF BRITISH COLUMBIA June 1988 © Chad Patrick Joseph Bennington, 1988 In presenting this thesis in partial fulfillment of the re-quirements for an advanced degree at the University of Brit ish Columbia, I agree that the Library shall make it freely available for reference and study. I further agree that permission for extensive copying of this thesis for scholarly purposes may be granted by the head of my department or by his or her representatives. It is un-derstood that copying or publication of this thesis for financial gain shall not be allowed without my written permission. Department of Chemical Engineering The University of British Columbia 1956 Main Mal l Vancouver, Canada V6T 1Y3 Date: / Abstract Initiation and maintenance of motion within a pulp suspension is necessary for effec-tive mixing. This requires imposition of forces greater than the network strength and depends on suspension rheology once motion begins. As pulp suspensions display non-Newtonian and solid-like behaviour, studies were conducted using profiled rotors which imposed stress within the body of suspensions contained in cylindrical devices. A con-centric cylinder device capable of high torques (85 N-m) and high rotational speeds (524 rad/s) was built to study pulp suspension dynamic behaviour. Most work used a profiled rotor 0.1 m in diameter with baffled housings 0.13 and 0.22 m in diamter. The yield stress of low consistency pulp suspensions were measured with a Haake RV12 Ro-tovisco concentric cylinder viscometer. Semi-bleached kraft pulp was used throughout the study. Some tests were made with stone groundwood and thermomechanical pulps. Yield stress measurements were made for nylon and Spectra-900 fibre suspensions. The yield stress of pulp suspensions, ry, have been measured and correlated with mass concentration ( C m ) and volumetric concentration (Cv) over the range 0.4 < C m (%) < 33. It was found that because of increasing gas content that correlations developed using the mass concentration were inaccurate above approximately 20% Cm. Correlations developed using the volumetric concentration were accurate over the full range tested. For a West-Coast semi-bleached kraft pulp, r y (Pa) = 1.40CV(%)2 7 2 . Once rotor motion was initiated, pulp suspensions exhibited two distinct regimes of behaviour. The first was a tangential-cavity regime in which predominantly tangential motion grew to fill the chamber as shear rate increased. When motion reached the outer housing wall a flow transition occurred, likely triggered by flow interaction with the housing baffles. The subsequent post-transition regime was characterized by radial and axial flow that effectively mixed the suspension on both the macroscale and fibre-scale. The flow transition appeared to be what earlier workers reported as the onset of "fluidization". During tangential-cavity flow, phase segregation occurred. Gas present in the sus-pension collected around the rotor and reduced momentum transfer from the rotor to the suspension. This caused the torque for the pulp suspension to fall below that for water at the same rotational speed, and the cessation of flow development in the chamber. If sufficient momentum transfer was attained to initiate post-transition flow, the chamber contents became effectively mixed. The torque could still fall below that of water depending on the effective density of the suspension in the rotor vicinity. i i i C o n t e n t s A b s t r a c t i i L i s t o f T a b l e s x L i s t o f F i g u r e s x i i i A c k n o w l e d g e m e n t s x v i i i 1 M i x i n g P u l p S u s p e n s i o n s 1 1.1 Introduction 1 1.2 Mixing and Mixing Scales 2 1.3 Pulp Suspension Rheology 7 1.4 Mixers in Pulp Bleaching 11 1.4.1 Continuous Stirred Tanks 11 1.4.2 In-Line Static Mixers 14 1.4.3 In-Line Dynamic Mixers 15 1.4.3.1 Stirred Vessels 15 1.4.3.2 Peg Mixers 15 1.4.3.3 High-Shear Mixers 16 1.4.4 Mixing in Pipe Contractions and Expansions 17 1.4.5 Evolution of Pulp Mixers 18 1.5 Bleaching Chemistry and Mixing 20 iv 1.5.1 Bleaching Kinetics 20 1.5.2 Laboratory Results 22 1.5.3 Mi l l Experience 23 1.5.4 Mixing Rate 23 1.6 Mixing Gases into Pulp Suspensions 25 1.7 Measurement of Mixing Quality 27 1.7.1 Direct Measurement of Macroscale Mixing 28 1.7.2 Direct Measurement of Fibre-Scale Mixing 30 1.7.3 Estimates of Mixing Quality 31 1.7.3.1 Mixing Power 32 1.7.3.2 Mixing Energy 32 1.7.3.3 Shear Rate 34 1.7.3.4 Mixer Residence Time 35 1.8 Criteria for Good Mixing 35 1.9 Research Objectives 36 2 S t r e n g t h o f F i b r e N e t w o r k s 38 2.1 Introduction 38 2.2 Literature Review 39 2.2.1 Strength of Pulp Fibre Networks 39 2.2.2 Strength of Man-Made Fibre Networks 41 2.2.3 Tensile Strength of Fibre Floes 43 2.2.4 Tensile Strength of Wet Webs 45 2.2.5 Summary of Present Knowledge 46 2.3 Experimental 46 2.3.1 Objective 46 2.3.2 Equipment 48 v 2.3.3 Fibre and Suspension Properties 48 2.3.4 Procedure 49 2.3.4.1 Suspension Preparation . 49 2.3.4.2 Measurement Procedures 51 2.4 Results and Discussion 52 2.4.1 Yield Stress 52 2.4.1.1 Yield Stress Determination 52 2.4.1.2 Distribution of Measured Yield Stresses 58 2.4.1.3 Suspension Behaviour after Yielding 60 2.4.2 Pulp Fibre Network Strength 64 2.4.3 Man-Made Fibre Network Strength 67 2.4.3.1 Nylon Fibres 67 2.4.3.2 Spectra 900 Fibres 70 2.4.4 Analysis 70 2.4.4.1 Combined Experimental Findings 70 2.4.4.2 Theory of Network Failure at a Cylindrical Surface . . 73 2.4.4.3 Comparison with Other Work 80 2.5 Conclusions 82 2.6 Recommendations for Future Work 85 3 Dynamic Behaviour of Pulp Suspensions 86 3.1 Introduction 86 3.2 Literature Review 86 3.2.1 "Fluidization" of Pulp Suspensions : . . . 86 3.2.2 Disruption of Pulp Networks 89 3.2.3 Viscosity of Fibrous Suspensions 91 3.2.4 Characterization of Mixers 96 v i 3.3 Experimental 98 3.3.1 Objective 98 3.3.2 Equipment . 98 3.3.3 Fibre and Suspension Properties 100 3.3.4 Procedure 100 3.4 Results and Discussion 102 3.4.1 Preliminary Tests and Test Reproducibility 102 3.4.2 Wide-Gap Experiments 108 3.4.2.1 Torque vs. Rotational Speed Curves 109 3.4.2.2 Yield 112 3.4.2.3 Tangential-Cavity Regime 112 3.4.2.4 Flow Transition 118 3.4.2.5 Post-Transition Regime 119 3.4.2.6 Prediction of the Flow Transition 125 3.4.2.7 Phase Separation 127 3.4.3 Narrow-Gap Experiments 130 3.4.3.1 Torque vs. Rotational Speed Curves 130 3.4.3.2 Yield 134 3.4.3.3 Tangential-Cavity Regime 134 3.4.3.4 Flow Transition 136 3.4.3.5 Phase Separation 136 3.4.4 Floe Behaviour 137 3.4.5 Dynamic Behaviour of Different Pulps 137 3.5 Comparison with Results of Gullichsen and Harkonen 140 3.6 Characterization of Suspension Fluid-Like Behaviour 141 3.6.1 Power Number During Dynamic Pulp Tests 142 3.6.2 Power at the Point of Flow Transition 143 vii 3.6.3 Comparison of Pulp Suspension Viscosities Estimated 147 3.7 Summary and Conclusions 149 3.8 Recommendations for Future Work 150 N o m e n c l a t u r e 152 B i b l i o g r a p h y 157 A p p e n d i c i e s 171 A P u l p F l u i d i z e r a n d H a a k e R V 1 2 171 A . l Pulp Fluidizer Design 171 A . 2 Haake RV12 Viscometer 180 B C o m p u t e r P r o g r a m s 182 B. l Pulp Fluidizer Data Acquisition Computer Program 182 B. 2 Pulp Fluidizer Yield Stress Determination Computer Program 183 C F i b r e a n d S u s p e n s i o n P r o p e r t i e s 198 C. l Aspect Ratio 198 C.2 Elastic Modulus 199 C.3 Water Retention Value 200 C.4 Estimating Suspension Volume Concentration 202 D L i t e r a t u r e S e a r c h e s 220 E F i b r e S u s p e n s i o n Y i e l d S t r e s s T e s t D a t a 239 F D y n a m i c T e s t D a t a 269 G V e l o c i t y a n d T u r b u l e n c e M e a s u r e m e n t s 285 viii G. l Laser Doppler Velocimeter 285 G.2 High Speed Cinematography 286 H C h a n g e s i n P u l p P r o p e r t i e s D u r i n g D y n a m i c T e s t s 288 I D i s s o l u t i o n o f C h l o r i n e B u b b l e s 300 1.1 Introduction 300 1.2 Literature Review 301 1.3 Experimental 303 1.4 Results and Discussion 304 1.5 Conclusions 307 1.6 Recommendations for Future Work 308 J M e a s u r e m e n t o f D i f f u s i o n i n P u l p S u s p e n s i o n s 310 J . l Introduction 310 3.2 Literature Review 310 J.3 Experimental 311 J.4 Discussion 312 J.5 Conclusions 315 J.6 Recommendations for Future Work 316 K M i x i n g A s s e s s m e n t i n P u l p S u s p e n s i o n s U s i n g O p t i c a l S e n s o r s 3 1 7 K . l Introduction 317 K.2 Experimental Program 319 K.3 Results and Discussion 320 K.4 Conclusions 325 ix L i s t o f T a b l e s 1.1 Mixing scales in pulp bleaching 4 1.2 Power to "fluidize" pulp suspensions 10 1.3 Relative power dissipation in a CST . 1 3 1.4 Mixers used for pulp bleaching 19 1.5 Relative mixing rates in common pulp mixers 24 1.6 Macroscale mixing quality of pulp mill mixers 29 1.7 Fibre-scale mixing quality of pulp mill mixers 31 1.8 Comparison of mixers used in pulp bleaching 33 2.1 Summary of fibre and suspension properties 50 3.1 Comparison of chamber dimensions used in the Gullichsen and Harkonen tests with the wide-gap configuration . . . 108 3.2 Phase separation in dynamic tests. Semi-bleached kraft (SBK-2) in the wide-gap configuration 129 3.3 Apparent viscosity at the point of flow transition for semi-bleached kraft pulp (SBK-2) in the wide-gap configuration determined using power number correlations 143 3.4 Apparent viscosity of semi-bleached kraft at the point of flow transition determined by mixer power number correlation and power dissipation. . 147 A . l Specifications of rotor designs: Pulp fluidizer and Haake RV12 177 A.2 Specifications of pulp fluidizer housings 178 A.3 Response time of fluidizer measuring sensors 179 x A. 4 Specifications of Haake RV12 Rotovisco housing 181 B. l Pulp fluidizer data acquisition computer program 184 B. 2 Pulp fluidizer yield stress determination computer program 194 C l Dimensions of pulp and man-made fibres 205 C. 2 Typical pulp fibre dimensions 206 C.3 Identification and source of pulp fibres 207 C.4 Stiffness of pulp and man-made fibres 217 C. 5 Water retention value (WRV) and fibre saturation point (FSP) of pulp and man-made fibres 219 D. l Literature search: Chlorination reaction kinetics 221 D.2 Literature search: Mixing of pulp suspensions 223 D.3 Literature search: Yield stress of pulp fibre suspensions 232 D.4 Literature search: Yield stress of man-made fibre suspensions 234 D.5 Literature Search: Tensile strength of man-made and pulp fibre floes. . . 236 D. 6 Literature Search: Viscosity of fibre suspensions 237 E. l Yield stress of semi-bleached kraft pulp: SBK-1 242 E.2 Yield stress of semi-bleached kraft pulp: SBK-4 243 E.3 Yield stress of stone groundwood pulp: SGW-1 244 E.4 Yield stress of themo-mechanical pulp: T M P - 1 245 E.5 Yield stress of 15 denier 2 mm nylon fibres in a 33% wt/wt solution of sucrose in water 245 E.6 Yield stress of 15 denier 3 mm nylon fibres in a 33% wt/wt solution of sucrose in water 246 E.7 Yield stress of 15 denier 5 mm nylon fibres in a 33% wt/wt solution of sucrose in water 246 E.8 Yield stress of 15 denier 7 mm nylon fibres in a 33% wt/wt solution of sucrose in water 247 xi E.9 Yield stress of 15 denier 5 mm nylon fibres in water 247 E.10 Yield stress of 3.3 mm Spectra 900 fibres in a 19% wt/wt solution of ethanol in water. 248 E . l l Yield stress of 6.2 mm Spectra 900 fibres in a 19% wt/wt solution of ethanol in water 249 E.12 Yield stress of a 33.6% Cm semi-bleached kraft pulp as a function of volume concentration 250 E.13 Yield stress of a 30.8% C m stone groundwood pulp as a function of volume concentration 250 E.14 Yield data for all tests 251 E.15 Linear regression results: Mass concentration vs. yield stress 266 E. 16 Multiple linear regression results: Suspension and fibre properties vs. yield stress 267 F. l Conditions of dynamic tests conducted with the pulp fluidizer 271 F.2 Power dissipated at the point of flow transition: Semi-bleached kraft (SBK-2) 279 F.3 Power dissipated at the point of flow transition: Semi-bleached kraft (SBK-4) 283 F.4 Power dissipated at the point of flow transition: Stone groundwood (SGW-1) 284 F.5 Power dissipated at the point of flow transition: Thermomechanical pulp (TMP-1) 284 H.l Pulp properties vs. energy treatment in the pulp fluidizer 297 H.2 PF I mill results: SBK-2 299 K . l Filtering and sampling used for Opticlor signal analysis 320 xii L i s t o f F i g u r e s 1.1 Scales of mixing in pipe flow 3 1.2 Non-uniformities introduced by chemical injection 7 1.3 Bulk flow in a CST 12 1.4 Zones of power dissipation in a CST 13 1.5 Intense shear created in high-shear mixers 17 2.1 Literature data on the strength of pulp fibre networks. 47 2.2 Stress vs. rotor angular displacement for a 1.6% Cm semi-bleached kraft pulp 53 2.3 Torque vs. rotational speed for a 0.8% Cm semi-bleached kraft pulp . . . 55 2.4 Measured yield stress vs. rotor acceleration rate 56 2.5 Yield stress determination for a 10.6% Cm semi-bleached kraft pulp . . . 57 2.6 Distribution of relative yield stress measurements for all tests 59 2.7 Distribution of relative yield stress measurements for all pulp tests. . . . 59 2.8 Distribution of relative yield stress measurements for all man-made fibre suspension tests 60 2.9 Relative torque vs. rotational speed for a 1.5% C m stone groundwood pulp 61 2.10 Relative torque vs. rotational speed for a 3.0% Cm stone groundwood pulp 62 2.11 Relative torque vs. rotational speed for an 8.0% Cm stone groundwood pulp 63 2.12 Yield stress vs. mass concentration for pulp fibre suspensions 65 xiii 2.13 Yield stress vs. volume concentration for a 33.6% Cm semi-bleached kraft and a 30.8% Cm stone groundwood pulp 68 2.14 Yield stress vs. mass concentration for nylon fibre suspensions 69 2.15 Yield stress vs. mass concentration for 5 mm nylon fibre suspensions in water and a 33% wt/wt sucrose/water solution 71 2.16 Yield stress vs. mass concentration for Spectra 900 fibre suspensions. . . 72 2.17 Forces due to fibre bending 74 2.18 Photographs of semi-bleached kraft, stone groundwood and thermome-chanical pulp fibres 78 2.19 Photographs of 2 mm nylon and 3.3 mm Spectra 900 fibres 79 2.20 Measured vs. predicted yield stress for all data 81 2.21 Yield stress vs. mass concentration for semi-bleached kraft pulp com-pared with literature data 84 3.1 Torque vs. rotational speed response of pulp in dynamic shear test as measured by Gullichsen and Harkonen 87 3.2 Relative viscosity predicted by equations in the literature 94 3.3 Pulp fluidizer rotor and housing configurations used in dynamic tests . . 99 3.4 Rotational speed vs. time for a 10% Cm semi-bleached kraft pulp in a standard test 101 3.5 Hysteresis present in the torque vs. rotational speed curve of a 10% C m semi-bleached kraft pulp 103 3.6 Shaft torque due to friction forces in the pulp fluidizer 105 3.7 Test reproducibility: 10% Cm SBK-2 106 3.8 Test reproducibility: 16% Cm SBK-2 107 3.9 Torque vs. rotational speed curves for SBK-2 : 0, 2, 4, 6 and 8% C m in the wide-gap configuration 109 xiv 3.10 Torque vs. rotational speed curves for SBK-2 : 10, 12, 14 and 16 % C m in the wide-gap configuration 110 3.11 Torque vs. rotational speed curves of 9.2-9.6% SBK-2 made at different rotor acceleration rates I l l 3.12 Regimes of semi-bleached kraft suspension behaviour in the wide-gap configuration 113 3.13 Fluid-like zone of pulp motion increases with shear rate 114 3.14 Flow of a 5.94% C m semi-bleached kraft pulp in the wide-gap configura-tion at 1230 rpm 115 3.15 Radial extent of active zone vs. that predicted using a torque balance . 117 3.16 Post-transition flow profile viewed along the housing axis 120 3.17 Flow of a 5.94% Cm semi-bleached kraft pulp in the wide-gap configura-tion at 2500 rpm 122 3.18 Red fibre distribution on the macroscale following a standard test . . . . 123 3.19 Red fibre distribution on the fibre-scale following a standard test . . . . 124 3.20 Torque vs. rotational speed curves for water and glycerol tested in the wide-gap configuration 131 3.21 Torque vs. rotational speed curves for SBK-2 at 0, 2, 4 and 6% Cm in the narrow-gap configuration 132 3.22 Torque vs. rotational speed curves for SBK-2 at 0, 8.3, 9.2 and 11.7% Cm 133 3.23 Regimes of semi-bleached kraft suspension behaviour in the narrow-gap configuration 135 3.24 Torque vs. rotational speed curves made with 10% Cm semi-bleached kraft, stone groundwood and thermomechanical pulp 138 3.25 Torque vs. rotational speed curves made with stone groundwood pulp in the wide-gap configuration 139 3.26 Power number vs. Reynolds number for the pulp fluidizer 142 xv 3.27 Power dissipation at the point of flow transition 145 3.28 Relative viscosity determined for semi-bleached kraft pulp compared with literature correlations 148 A . l Photograph of pulp fluidizer 172 A.2 Side view of pulp fluidizer 173 A.3 Front view of pulp fluidizer 174 A.4 Plan view of pulp fluidizer 174 A.5 Detail of pulp fluidizer shaft 175 A.6 Shaft torque vs. rotational speed for the pulp fluidizer 175 A.7 Pulp fluidizer rotors used in yield and dynamic tests 176 C I Fibre length distributions of semi-bleached kraft pulp (SBK-1) 208 C.2 Fibre length distributions of stone groundwood pulp (SGW-1) 209 C.3 Fibre length distributions of thermomechanical pulp (TMP-1) 210 C.4 Fibre length distributions of 2 mm nylon fibres 211 C.5 Fibre length distributions of 3 mm nylon fibres 212 C.6 Fibre length distributions of 5 mm nylon fibres 213 C.7 Fibre length distributions of 7 mm nylon fibres 214 C.8 Fibre length distributions of 3.3 mm Spectra 900 fibres 215 C.9 Fibre length distributions of 6.2 mm Spectra 900 fibres 216 H.l Curl vs. energy treatment for SBK-2 fibres in the narrow-gap configura-tion of the pulp fluidizer 289 H.2 Photographs of semi-bleached kraft pulp (SBK-2) before and after treat-ment in the narrow-gap configuration of the pulp fluidizer 290 H.3 Tear index vs. tensile strength for SBK-2 292 H.4 Tensile strength vs. energy input for SBK-2 treated in the pulp fluidizer. 293 H.5 Tear index vs. energy input for SBK-2 treated in the pulp fluidizer. . . . 294 H.6 C S F vs. energy input for SBK-2 treated in the pulp fluidizer 295 xvi 1.1 Dissolution of a 2 ^1 chlorine bubble 304 1.2 Successive dissolution tests of 2 fi\ chlorine bubbles 306 J . l Images of M n 2 + diffusion through a 3.0% Cm semi-bleached kraft pulp . 313 J.2 Diameter of the diffusion zone of M n 2 + in a 3.0% C m semi-bleached kraft pulp vs. time 314 K . l Process signal from the Opticlor sensor 319 K.2 Power spectra of analysis P R O P T . l 321 K.3 Power spectra of analysis P R O P T . 2 322 K.4 Power spectra of analysis P R O P T . 3 323 xvi i A c k n o w l e d g e m e n t s Many individuals have contributed to this research and their assistance is gratefully acknowledged: Dr. R. J . Kerekes and Dr. J . R. Grace for their guidance, suggestions and valuable discussions throughout the course of this research. Dr. K. L. Pinder for his helpful discussions concerning the yield stress of pulp suspen-sions and assistance with the Haake RV12. Dr. R. Seth for his help interpreting the physical changes to pulp samples treated in the pulp fluidizer. Dr. N. Burlinson for obtaining the N M R images of manganese ion diffusing through pulp suspensions. Members of the Pulp and Paper Centre, Chemical Engineering Department and the Pulp and Paper Research Institute of Canada for their help in many aspects of this research. Members at the Powell River division of MacMil lan Bloedel Limited and at the Howe Sound division of Canadian Forest Products Limited for supplying the pulp samples used in this research. Financial support in the form of scholarships from the Natural Sciences and Engineering Research Council of Canada and the Pulp and Paper Research Institute of Canada allowed me to continue this research and are greatly acknowledged. xvii i For my Parents and Maureen x i x C h a p t e r 1 M i x i n g P u l p S u s p e n s i o n s 1.1 I n t r o d u c t i o n Mixing is an essential unit operation in pulp and paper manufacture. The success of many common pulp and paper processes depends upon effective mixing, including the blending of different pulp stocks in papermaking, reduction of consistency fluctuations ahead of a papermachine, steam addition to a pulp stream, and the contacting of chemicals with pulp in a bleaching stage. However, nowhere is mixing more crucial than in pulp bleaching where each fibre of a pulp suspension must be brought into contact with the correct amount of bleaching chemical. To a large degree it is the quality of mixing achieved in each bleaching stage that determines the uniformity, strength, and quality of the final bleached product. As ef-fective mixing also minimizes the quantity of chemical required to achieve any specified degree of bleaching, substantial cost savings are also possible. These benefits have made the quest for improved mixing very attractive to mills. However, good mixing remains an elusive target. Not only is it difficult to assess the quality of a pulp mixture, but the trend of bleaching pulp at higher consistencies has made mixing greatly more complex than is the case in low consistency suspensions. While mixing has been extensively studied for many systems [Brodkey, 1975a; Hol-land and Chapman, 1966; Mann, 1983; Nauman and Buffham, 1983; Oldshue, 1983; 1 CHAPTER 1. MIXING PULP SUSPENSIONS 2 Silvester, 1985; Sterbeck and Tausk, 1965; Uhl and Gray, 1966, 1986; Ulbrecht and Pat-terson, 1985; Villermaux, 1986], information available on mixing pulp suspensions is limited mainly to blending operations [Attwood and Gibbon, 1963; Oldshue and Gret-ton, 1956; Walker and Cholette, 1958]. This is due in part to the complex rheology of pulp fibre suspensions. This chapter reviews our current understanding of mixing in pulp bleaching and brightening applications, covering low (LC : 0-8% C m x ) , medium (MC: 8-20% Cm), and high (HC: 20-40% C m ) consistency operations. It examines the types of mixers used, the benefits of improved mixing and the methods currently available to measure mixing in mill situations. 1.2 M i x i n g a n d M i x i n g S c a l e s Mixing is achieved by the movement of material between various parts of a bulk mass to reduce the non-uniformities or gradients of the property of interest to an acceptable level. These non-uniformities may be of varying scales, as illustrated by a hypotheti-cal longitudinal concentration profile along the center-line of a pipe as shown in Fig-ure 1.1(a). Here, concentration variations may span a wide spectrum of sizes — from distances large with respect to a pipe diameter down to distances on the order of a fibre length or less. The aim of a good mixing system is to achieve homogeneity on all scales. While there are a. number of ways to define scales of non-uniformity, one useful ba-sis is the distance of relative motion required to even out variations. As illustrated in Figure 1.1(b) macroscale variations may be defined as those requiring substantial back-flow, i.e. bulk movement of fluid over large distances. On the other hand, small-scale variations can be mixed by shear — local fluid movement induced by velocity gradi-ents or turbulence, and by diffusion — molecular movement induced by concentration 1The mass concentration of a fibre suspension is the weight of dry fibre divided by the weight of the suspension. Standard test procedures are given by CPPA D.16 and TAPP1 T240 om-81. CHAPTER 1. MIXING PULP SUSPENSIONS 3 Concentration Small-scale Large-scale mixing by bulk flow Small-scale mixing by local shear and diffusion (b) Figure 1.1: Process flows may have concentration fluctuations that span a spectrum of scales or distances as shown in (a). Bulk motion eliminates large-scale (macroscale) variation while local shear and diffusion eliminates small-scale (fibre-scale and mi-croscale) variation as shown in (b). CHAPTER 1. MIXING PULP SUSPENSIONS 4 Table 1.1: Mixing scales in pulp bleaching. Mixing Scale Approximate Mixing Achieved Dimension Designation Size (mm) Primarily by large macroscale >10 bulk motion small fibre-scale 0.05-10 laminar and turbulent shear, diffusion small microscale <0.05 diffusion aided by small-scale fluid motion gradients. As fibre suspensions are discontinuous over small distances it is useful to define two small scales of mixing: the fibre scale to represent non-uniformities on the fibre and floe level, and the microscale to represent non-uniformities approaching the molecular level. Table 1.1 summarizes these important mixing scales. P.V. Danckwerts pioneered our understanding of mixing. He developed residence time distribution theory to characterize macroscale mixing [1953a] and developed con-cepts that enabled small-scale mixing to be qualified and quantified [1952, 1953b]. His concepts may be used to describe mixing in pulp suspensions which can be pictured as occurring in a number of steps. First, bulk motion is used to achieve macroscale uniformity, although the additive (the bleaching chemical) can still exist in discrete clumps or segregated regions within the mixture. Small-scale uniformity is achieved by breaking up these segregated regions into smaller and smaller sizes. This is achieved by local shearing forces produced by mean and turbulent flow created within the mixture. A reduction in the size of the segregated regions markedly increases the surface area of the additive. Finally, molecular diffusion causes a spreading of the additive from the segregated regions, achieving ultimate microscale uniformity. To characterize microscale mixing quantitatively, Danckwerts developed two sta-tistical parameters: the scale of segregation, L31 and the intensity of segregation, The scale of segregation can be defined [Danckwerts, 1952; Brodkey, 1975b] in terms of CHAPTER 1. MIXING PULP SUSPENSIONS 5 the instantaneous concentration fluctuation, C , its average, C , its variation about the mean, c, and the root mean square of the concentration fluctuation, c' C = C + c (1.1) c' = V? (1.2) An Eulerian statistical correlation function is used to measure the similarity between concentration fluctuations at two points, x and x -\-r, where r is radially outward from x and is given by C(r) = c(x)c(x +r)/c'2 (1.3) The scale of segregation is an integral relation defined as L. = rC(r)dr (1.4) Jo As L, is an average over a large range of r, it is a measure of clump breaking processes but not of small-scale diffusional processes. The intensity of segregation is defined as h=^lc\ (1.5) where c' is defined by Equation 1.2 and c'a is the initial rms fluctuation. In the absence of mixing I, is unity. As mixing progresses, I, decreases, reaching zero when the mixture is uniform. Together, IB and L, provide a quantitative measure of small-scale mixing quality. However, for our purposes it is also useful to have a qualitative understanding of each variable. The scale of segregation can be pictured as the size of the segregated clumps within the suspension, while the intensity of segregation describes the difference in concentration between the clumps and the surrounding fluid. Small scale mixing in pulp suspensions proceeds by decreasing both the scale and intensity of segregation. This is represented by a movement to lower values of I, and L, as mixing progresses. CHAPTER 1. MIXING PULP SUSPENSIONS 6 Danckwerts [1953b] realized that any mixture, if examined closely enough, would show regions where the composition varies from point to point. Since the maximum tolerable size of these segregated regions varies in any given situation, he used the con-cept of the "scale of scrutiny" to describe the size below which variation in composition would not be important. This established a mixing target. But how good does mixing have to be in pulp bleaching? This is a difficult question to answer, although an initial estimate can be made for pulp chlorination. If our mixing target is to have every fibre contact chemical before leaving the bleach-ing tower, mixing must reduce the distance between peaks in chemical non-uniformity, i.e. the scale of segregation, to a distance less than that over which chlorine will diffuse during the residence time in the retention tower which follows mixing. The distance through which aqueous chlorine will diffuse and react in an unbleached pulp suspension was measured by Paterson and Kerekes [1984] as a function of time. For low consistency chlorination at 2.1% C m , chlorine was found to diffuse at most 3-5 mm in one hour. Thus for a typical chlorination stage with a residence time of one hour, the chlorine and pulp must be mixed to at least this level before entering the tower if our mixing target is to be met. Further, as pulp consistency is increased, the distance that chlorine will diffuse in any given time decreases. For example, for a 12.8% Cm pulp suspension this distance is only 1-2 mm. Thus, as we mix higher consistency pulp suspensions, the quality of mixing achieved by the mixer must improve. The diffusion of chemicals through pulp suspensions is discussed further in Appendix J . The non-uniformities to be removed by the mixer represent the "mixing load". These can originate external to the mixer, for example, due to flow or concentration fluctuations in the incoming pulp and chemical streams, or may be imposed by the mixing system geometry. The initial chemical contacting is particularly important. It not only begins the mixing process, but also determines, to a large degree, how much mixing is subsequently needed. Consider the two configurations presented for chemical CHAPTER 1. MIXING PULP SUSPENSIONS 7 CHEMICAL ADDITION CHEMICAL ADDITION PULP MIXER PULP MIXER 1 (a) (b) Figure 1.2: Non-uniformities can be introduced by the positioning of chemical injection in a mixer. The mixing load imposed by configuration (a) is larger than that imposed by configuration (b). injection to a mixer shown in Figure 1.2. In both scale of non-uniformity is introduced related to the distance over which the added material must be transported to the furthest location in the mixer. Clearly, in the second case this distance is smaller and results in a smaller mixing load. Consequently, less mixing is required to attain a desired level of uniformity. It is important to realize that while non-uniformities entering the mixer are imposed by external factors, the mixing load imposed by the positioning of the chemical injection point is controllable by mixer design. Better mixing can often be achieved by lowering the mixing load as opposed to increasing the mixing. Mixing is usually produced by creating relative motion within the pulp suspension. This requirement makes pulp suspensions uniquely difficult to mix due to their complex rheology. 1.3 Pulp Suspension Rheology Pulp suspensions can consist of three phases: solid (the pulp fibres), liquid (usually water) and gas (air or bleaching chemical). In many applications, pulp suspensions can CHAPTER 1. MIXING PULP SUSPENSIONS 8 be considered to consist primarily of water and fibre. This occurs for low consistency pulp suspensions (0-6%). In these cases the mass concentration or consistency ( C m ) is sufficient to describe the suspensions. However, as the pulp consistency increases above 6-8% a significant amount of air may be present in the suspension [Dosch et al., 1986]. In addition, when gases are added to the suspension, as in M C chlorination or oxidative extraction, the gas phase can make up a substantial portion of the total suspension volume. In these instances the gas phase becomes extremely important in determining suspension rheology and mass concentration alone is not sufficient to describe suspension composition. Pulp suspensions are continuous fibre networks that possess structure and strength resulting from interaction between neighbouring fibres. In suspensions above 0.5% Cm cohesive strength arises from mechanical forces caused by the bending and hooking of fibres [Kerekes et al., 1985]. As the consistency of the suspension increases, the number of fibre/fibre interactions increases, and this in turn increases network strength. The distribution of fibres in networks is never uniform, and local mass concentrations of fibres give rise to floes within the suspension. Since network strength depends on the number of fibre contacts, floes have a higher strength than the surrounding suspension. Thus, floes are not only regions of higher fibre mass concentration but they are also regions of greater strength than the surroundings. In a flowing pulp suspension, floes may behave as independent entities. At medium consistency (8-20%) the strength and non-uniformity of fibre networks are further increased. The greater number of interfibre contacts substantially increases network and floe strength, while the presence of a gaseous phase creates surface tension forces among the fibres which adds to this strength. At the upper concentration end of the M C range, the nature of the pulp suspension begins to change from one of mass concentrations of fibres in water to one of wet fibre aggregates surrounded by gas. This heterogeneous three-phase system can usually be considered a porous medium. CHAPTER 1. MIXING PULP SUSPENSIONS 9 At high consistency (20-40%), the suspension becomes a network of wet fibre ag-gregates surrounded by gas. The void ratio in this range is sufficiently great that the network is a permeable medium, with a much lower resistance to gas flow in the inter-floc spaces than in the intra-floc passages. Thus, fibre floes in this consistency range present an "aerodynamic specific surface" to the flowing gas which is substantially less than the specific surface of an individual fibre, i.e. 50 m 2 / kg versus approximately 1000 m 2 / kg [Garner and Kerekes, 1978]. Thus, while a gas readily flows through the sus-pension there may be very little contact between gas and the majority of fibres unless the floes are broken up in some manner. In mixing it is important to cause motion throughout the suspension. This requires the imposition of shear stresses greater than the strength of the pulp network. The many measurements of pulp network strength have been summarized by Kerekes et al. [1985]. Although there are differences among these results, they show a marked dependency on consistency and can be represented by T = aCmb (1.6) where r is the strength of the pulp network in Pascals, C m the mass concentration in percent and a and b fitted constants. Values of the constant, a, between 1.18 and 24.5, and values of the exponent, 6, between 1.26 and 3.02 have been reported for low consistency suspensions [Kerekes et a/., 1985]. It is thought that differences in test method and fibre type account for the variation in reported values. A detailed discussion of fibre network strength and experimental measurements of pulp suspension yield stress over a wide consistency range can be found in Chapter 2. The initiation of motion in a pulp suspension first occurs at the weak zones of sus-pension, that is, between floes. As the applied shear is increased, the relative motion between floes increases and a reduction in floe size occurs [Kerekes, 1983]. A further increase in shear causes more violent movement and leads eventually to turbulent flow. CHAPTER 1. MIXING PULP SUSPENSIONS 10 Table 1.2: Power to "fluidize" pulp suspensions. Pulp Mass Power for Network Disruption Concentration e, W / m 3 Cm, % Gullichsen and Harkonen [1981] Wahren [1980] 2 - 4.5 x 105 4 5.3 x 104 1.8 x 10 7 6 1.0 x 10 5 1.5 x 108 8 2.7 x 105 6.8 x 108 10 8.8 x 105 2.2 x 109 12 2.1 x 106 5.8 x 109 15 - 1.9 x 10 1 0 25 - 2.8 x 10 1 1 35 - 1.6 x 10 1 2 Gullichsen and Harkonen [1981] observed the conditions under which pulp suspensions became turbulent in a concentric cylinder apparatus. This behaviour has been termed "fluidization", and the achievement of a "fluidized" state has become a design param-eter for the high-shear medium consistency mixers. When the application of shear creates movement, power is consumed. The power dissipated per unit volume, e, is related to the shear rate and viscosity in both laminar and turbulent flow, with increased power dissipation generally increasing the extent and intensity of relative motion within the fluid. Power dissipation has been used to characterize the onset of fluid-like behaviour in pulp suspensions. For example, the power to "fluidize" an unbleached kraft pulp suspension measured by Gullichsen and Harkonen [1981] is compared with estimates of the power required to disrupt a pulp network made by Wahren [1980] in Table 1.2. It is apparent that at any given consistency a large discrepancy exists between the measured and estimated values — roughly three orders of magnitude. There are a number of possible explanations for this discrepancy. One is Wahren's use of the viscosity of water to characterize the viscosity CHAPTER 1. MIXING PULP SUSPENSIONS 11 of a pulp suspension. Once a pulp suspension is "fluidized", it can be assigned an apparent viscosity, which for a medium consistency pulp suspension is assuredly much greater than that of water [Rutgers, 1962, 1963; Krieger, 1967]. Another explanation is a differing interpretation of what constitutes "fluidization". For example, relative motion may exist at the floe level, fibre level, or indeed at both levels in flows with large shear gradients. Reasons for this discrepancy as well as more detailed discussion of pulp suspension fluid-like behaviour is given in Chapter 3. 1.4 M i x e r s i n P u l p B l e a c h i n g The rheological properties of pulp suspensions discussed above have always governed the design of mixers used for pulp bleaching. Mixers have evolved over the years with the changing needs of bleaching processes, and it is illuminating to examine this development. In the following discussion, attention will focus on the hydrodynamic principles of each class of mixer and the ability of these mixers to achieve macroscale, fibre-scale, and microscale mixing of pulp suspensions. This discussion begins with a consideration of the most widely used mixer in industry — the continuous stirred tank (CST). 1.4.1 C o n t i n u o u s S t i r r e d T a n k s The CST is widely employed in pulp mixing and blending operations, and in the past was commonly used for low consistency pulp chlorination. The CST is simply a vessel containing one or more rotating impellers which produce bulk movement of fluid by a pumping action and create turbulence in the wake of rotating blades. Bulk flow in a CST is produced by the recirculating flow pattern as shown in Figure 1.3. Elements of the pulp suspension spend differing times in the mixer and therefore on recirculating meet different parts of the incoming flow. Through this CHAPTER 1. MIXING PULP SUSPENSIONS 12 BULK FLOW HIGH SHEAR o c z > Figure 1.3: The rotation of impellers in a C S T produces large-scale recirculating motion in the vessel, as well as shear and turbulence in the wake of rotating blades. process of backmixing, large-scale non-uniformities are eliminated. Good macroscale mixing is achieved in two ways. First, movement must occur at all points within the mixing vessel. This requires that the shear stress created by the impeller(s) be sufficient to rupture the fibre network even at remote zones in the vessel, a requirement that can only be met in the low consistency range. Second, there must be adequate residence time in the mixer in relation to the flow rate and scale of non-uniformities to be removed to achieve the desired macroscale mixing [Walker and Cholette, 1958; Reynolds et ai, 1964]. Mixing at the fibre-scale is achieved by fluid shear and turbulence produced in the flow leading away from the impeller(s). The distribution of shear varies over a wide range in a C S T , and has been quantified using the power dissipation into three principal zones: the impeller tip zone, the impeller zone, and the bulk zone [Tomi and Bagster, 1978] as shown in Figure 1.4. The relative power dissipation in each zone is given in Table 1.3 for a Newtonian fluid. The significance of this distribution in pulp mixing may be illustrated by the average power for agitation of a 4% consistency kraft pulp in CHAPTER 1. MIXING PULP SUSPENSIONS 13 IMPELLER TIP ZONE IMPELLER ZONE Figure 1.4: The CST can be divided into three mixing zones: the bulk, impeller and impeller tip. The energy dissipated in each zone differs greatly as shown in Table 1.3. Table 1.3: Relative power dissipation in the mixing zones of a C S T after Tomi and Bagster [1978]. CST Volume Power Mixing Fraction Dissipation Zone (%) ^zone / ^ avg Bulk 90.0 0.25 Impeller 9.5 5.4 Impeller T ip 0.5 50 CHAPTER 1. MIXING PULP SUSPENSIONS 14 in a CST: between 1 and 2 HP/1000 USG (200-400 W / m 3 ) [Bates et al., 1966]. Using the relative power distribution given in Table 1.3, the power dissipation in the impeller tip zone is 1.0-2.0xl0 4 W / m 3 and is close to that for "fluidization" of a 4% Cm pulp suspension measured by Gullichsen and Harkonen. As other regions in the vessel have power dissipation rates much lower than this value, the most intense suspension motion and fibre-scale mixing occur only in this region. The above discussion implies that the amount of shear imposed on a portion of a pulp suspension depends on the number of times it is circulated through the impeller tip zone. Therefore, as there is a distribution of residence times in a CST , not all of a suspension is subjected to the same fibre-scale mixing. This points out the principal advantage and disadvantage of a CST : it produces both macroscale mixing and fibre-scale mixing, but by virtue of producing the former, it cannot produce a uniform level of the latter. However, uniform fibre-scale mixing is required in bleaching since each fibre must be uniformly contacted with reagent. 1.4.2 I n - L i n e S t a t i c M i x e r s Static mixers consist of a series of stationary elements positioned in a section of piping. There are many proprietary designs for these mixers [Cybulski and Werner, 1986; Pahl and Muschelknautz, 1979], but generally all achieve fluid mixing by dividing and re-combining the flow ("cutting and turning"), by generating turbulence in the flow, or by a combination of these two mechanisms. The key feature of a static mixer is that the entire flow is subjected to a similar degree of shear which ensures uniform fibre-scale mixing. The energy for mixing is extracted from the mean flow. While static mixers achieve a good level of small-scale mixing, they do not eliminate large macroscale variations in the flow. Moreover, because the mixing is linked to the suspension flow velocity and thus the production rate of the bleach plant, static mixers also have small turndown ratios and must be correctly sized for each application. CHAPTER 1. MIXING PULP SUSPENSIONS 15 Static mixers are generally used to mix low consistency pulp suspensions. They have, however, also been used as mixers in medium consistency applications with ap-propriate means of chemical addition [Swenson, 1976]. Since they cannot generate the intense shear required to create turbulent motion in M C pulp suspensions, they must rely on cutting and turning to mix at this consistency. To create fluid-like behaviour in M C suspensions, shear must generally be imposed from external sources. 1.4.3 I n - L i n e D y n a m i c M i x e r s The imposition of shear through external mechanical means decouples the shear gen-erated in a mixer from the pulp throughout. Higher shear may be imposed by the use of high rotational speeds and/or narrow gaps between rotating and stationary mixer elements. 1.4.3.1 S t i r r e d V e s s e l s In the early days of commercial low consistency pulp chlorination, CST mixing zones were created in the bottom of the residence towers. CST type pre-mixers were also used. However, these did not provide sufficient mixing to obtain uniform chlorination [Casey, 1980]. In order to attain more uniform fibre-scale mixing, modified CSTs were developed. These reduced or eliminated the zones of low shear bulk motion, resulting in smaller vessels where pulp suspensions were subjected to higher shear and greater turbulence, for example, the Fiscalin and Hurricane mixers [Perkins and Doane, 1979]. Thus fibre-scale mixing was improved at the expense of macroscale mixing, although certain mixers were often used in series to increase the residence time. 1.4.3.2 P e g M i x e r s Mixing in medium and high consistency pulp suspensions has conventionally been achieved with peg mixers. These are tubular vessels in which one or two shafts with CHAPTER 1. MIXING PULP SUSPENSIONS 16 pegs rotate between stationary elements attached to the mixer casing. As pulp is con-veyed through the mixer, the rotating bars shear the suspension against the stationary elements. This shearing action creates transport through the suspension and exposes new fibre surface. Chemicals may be added ahead of the mixer or distributed inside the mixer through appropriately located injection ports. One M C peg mixer, the "swept area" mixer [Torregrossa et ai, 1981], has a specific design aim of achieving a target level of area swept out by the rotating pegs. In sweeping out tliis area a given fibre surface area per tonne of pulp is exposed. The swept area required for different applications was determined in pilot scale studies and was found to depend on the bleaching chemical used [Meredith, 1985]. Peg mixers have also been used to mix bleaching chemicals into high consistency pulp suspensions. High shear stresses are required to rupture the high consistency fi-bre networks and a number of mixers (such as the A B N and Sunds HC mixers) are specifically designed to do this. Even when the network is sheared, the transport of liquid from one fibre to another remains a difficult task as there is little free water in this consistency range and the pulp fibres readily absorb the bleaching liquids. Con-sequently, the emphasis in high consistency mixing must be placed on minimizing the mixing load by exposing a high fibre surface area to bleaching chemical. This may be achieved, for example, by the use of multiple chemical addition ports. 1.4.3.3 H i g h - S h e a r M i x e r s In high-shear mixers chemicals and pulp are mixed during passage through zones of intense shear. The high shear is created by imposing large rotational speeds across narrow gaps through which the pulp suspension is forced as illustrated in Figure 1.5. Although there are differences in design among high-shear pulp mixers they all attempt to create fluid-like behaviour of the pulp suspension in the mixer working zone. The intense shear rate and consequent intense power dissipation ensures floe disruption and CHAPTER 1. MIXING PULP SUSPENSIONS 17 V E R Y H I G H S H E A R I N N A R R O W G A P A L L F L O W P A S S E S T H R O U G H G A P Figure 1.5: Intense shearing forces are created in high-shear mixers. Shear is created by imposing high rotational speeds across narrow gaps through which the pulp suspension flows. good fibre-scale mixing. Since this requires high power expenditure, the mixing zone is kept small to minimize total power consumption. However, this leads to extremely short residence times which in turn precludes macroscale mixing. This inability to achieve macroscale mixing means that large-scale non-uniformities must be eliminated upstream of the mixer by other means. Moreover, it requires that flow of chemical and pulp to the mixing zone be uniform to avoid macroscale variations at the mixer exit. 1.4.4 M i x i n g i n P i p e C o n t r a c t i o n s a n d E x p a n s i o n s Turbulence can occur wherever a pulp suspension is subjected to intense power dissi-pation. For example, turbulence may occur in passage through centrifugal pumps, or in the wake of any flow elements (e.g. partially closed valves or sudden expansions in process lines) that cause boundary layer separation. These are flows of decaying turbu-lence because the energy input required to maintain a turbulent flow condition is not sustained. Fluid motion diminishes very quickly in decaying turbulence. For example, at 3% Cm cessation of inter-fibre motion leading to reflocculation occurs approximately CHAPTER 1. MIXING PULP SUSPENSIONS 18 0.005 seconds after the turbulence maximum is attained. The reflocculation time de-creases dramatically as consistency increases [Kerekes et a/., 1985]. Despite the rapid loss of mixing action in decaying turbulence, it can be used for mixing in the low consistency and medium consistency range. For example, in extractive oxidation, oxygen bubbles from a sintered metal sparger are mixed into the pulp flow discharging from a Kamyr M C pump prior to passage through an orifice plate and control valve. Good results have been reported [Pageau, 1987]. Indeed, Cirucci et al. [1987] conclude that this method permits oxygen to be mixed into medium consistency pulp as efficiently as with high-shear mixing. While decaying turbulence from the M C pump is thought to be a key factor in this mixing, the shear and turbulence induced by the orifice and sudden pipe expansion downstream, coupled with the low mixing load imposed by chemical addition through a sintered metal sparger in a small diameter pipe, also contribute to the good mixing. The relative contribution of these factors is unknown at the present time. 1.4.5 Evolution of Pulp Mixers In the 1950's and 60's, low consistency mixing was achieved primarily with propeller agitated vessels, while M C mixing was achieved with peg mixers. Since this time newer mixer technology has been gradually introduced into the mills. In 1982 a North Amer-ican mill chlorination survey [Reeve and Davis, 1982] indicated that static mixers were the dominant mixer in use for pulp chlorination. The 1980's also saw the introduction of high-shear M C mixers. These gained rapid acceptance on extractive oxidation and chlorine dioxide stages, and have been increasingly used for low consistency chlorina-tion [Berry, 1987]. The above evolution in mixer design has generally led to better mixing and more effective bleaching. A summary of pulp mixers used for bleaching applications is given in Table 1.4. Table 1.4: Mixers used for pulp bleaching. Mixer Type Mass Concentration, Cm,% Comments Low (1-8) Medium (8-20) High (20-40) CST Various residence times and configurations • Backmixing is generally good provided the CST is properly designed and short circuiting avoided. • Non-uniform fibre-scale mixing. • Mixing efficiency drops as pulp consistency increases. • Generally useful only up to 3-5% C m . IN-LINE STATIC cut and turn turbulence widely used widely used appears possible with appropriate means of chemical addition • All flow receives uniform treatment. • Plug flow through mixer and therefore no macroscale mixing. • Mixer must be properly sized for the flow expected. Small turndown ratio. • Many proprietary makes available. IN-LINE DYNAMIC stirred vessels peg mixers high-shear short residence time vessels with impellers intense, short duration mixing of pulp single and double shaft, swept area high power input with short residence times Suffers and shredders • CSTs reduced in size to acheive better small-scale mixing. Backmixing traded for uniform turbulence and shear. • Little or no macroscale mixing. Residence time in mixing zone as low as 0.05 second. • All flow treated equally. • Imposed shear is independent of production rate in bleach plant. PIPE CONTRACTIONS and EXPANSIONS decaying turbulence generated by flow through valves, etc. turbulence created in wake of MC pumps, flow through valves and expansions in process piping • Wake turbulence can be used for mixing. • Turbulence decays and relative motion ceases rapidly in downstream flow. Time of decay decreases with in-creasing consistency. CHAPTER 1. MIXING PULP SUSPENSIONS 20 1.5 B l e a c h i n g C h e m i s t r y a n d M i x i n g In 1953 Danckwerts wrote [1953b] that "unless the reasons for making up a mixture are known, it is impossible to decide whether or not it is badly mixed". The first step in gaining such an understanding for pulp bleaching is to examine bleaching reaction chemistry. 1.5.1 B l e a c h i n g K i n e t i c s Bleaching involves multiple simultaneous reactions with lignin and carbohydrate com-ponents in the pulp. Consequently both the quality and rate of mixing affect the efficiency of bleaching. Bleaching reactions typically follow a trend similar to that of pulp chlorination. Reaction is initially very rapid, followed by a falling rate period where the bleaching rate levels off. The amount of delignification that occurs is determined by the quantity of applied chemical. However, bleaching is not a linear function of the amount of applied chemical; after a point proportionately larger amounts of chemical are consumed as incremental amounts of lignin are removed. At the same time, undesirable degradation reactions take place with the carbohydrates [Dense and Annergren, 1979]. Modelling of pulp bleaching reactions has received considerable attention over the years. Laboratory experiments have attempted to elucidate the reaction kinetics and the rate-limiting step for a number of bleaching chemistries. However, these studies have not arrived at a consensus as to how bleaching reactions proceed. In pulp chlori-nation, for example, many models have been found to adequately describe the observed pulp delignification. These models can be grouped into two categories: homogeneous (where chemical reaction controls) and heterogeneous (where mass transfer controls). For example, Chapnerkar [1961], Russel [1966a, 1966b] and Ackert [1973] used various reaction controlled models, while Karter [1968, 1971] chose a model where internal CHAPTER 1. MIXING PULP SUSPENSIONS 21 mass transfer (diffusion of chlorine through the cell wall) controlled. On the basis of the information presented in the literature, it is not possible to determine which, if either, mechanism is correct. However, most workers favour the homogeneous models. Of the many potential chlorination models studied by Ackert [1973], a homogeneous model having three simultaneous reactions ^4(not removable from fibre) (1-7) ^(removable) (1.8) C(removable) (1.9) was found to best fit his experimental data. Each reaction was assumed to be first order with respect to chlorine and lignin concentration, i.e. - ^ = k[Cl2][L-Lf] (1.10) where Lf is the amount of lignin that cannot be removed in a single bleaching step. This model uses four adjustable parameters: the amount of lignin that cannot be removed from the pulp and three reaction rate constants. It accounts only for chlorine and the lignin within the pulp. No information is included on the reaction between chlorine and the cellulose fibres, a reaction known to influence pulp properties. Ackert's experimental runs were carried out in both a CST and in a differential flow reactor (chemical flow through a pulp pad). In the CST good contact between chemical and fibre was assured, while in the differential flow reactor the fibres could pack together and provide an external mass transfer limitation. Ackert used a further empirical factor to account for the slower reaction rate observed in the latter case. This finding illustrates the necessity for the correct amount of bleaching chemical to reach every pulp fibre. Mixing in a bleaching stage must create sufficient homogeneity, that is, be good enough to ensure that each fibre in the pulp suspension is contacted with bleaching L + Cl2 L + Cl2 M A + Cl2 ^ CHAPTER 1. MIXING PULP SUSPENSIONS 22 chemical during the reaction time permitted. When mixing is poor, some regions of pulp receive chemical in excess of that required and continue to consume chemical in less desirable side reactions, while other areas receive insufficient chemical and are not adequately bleached. The net effect is that additional chemical is needed to attain the required bleaching while a pulp of less than optimal strength is produced. 1.5.2 L a b o r a t o r y R e s u l t s The importance of mixing quality in pulp bleaching was recognized as early as 1966 when a laboratory study by Atkinson and Partridge [1966] showed that better mixing reduced the amount of chemical needed to reach a given bleached brightness as well as preserved pulp strength. While this study showed that there were benefits to improved mixing, attempts to quantify mixing quality came later. Torregrossa [1983], simulated various degrees of mixing in the laboratory by treating portions of a pulp sample with various chemical charges and later combining them in varying amounts. The properties of the artificially created pulp mixtures could then be determined. This technique, termed "charge deviation", allowed estimation of the potential mixing benefits available in a mill once the quality of mill mixing had been established. The laboratory study showed that as mixing improved, the chemical needed to reach a given brightness target was reduced, the shive count at a given chemical charge was reduced, and effective use was made of all bleaching chemical. Similar results were obtained by Backlund and Parming [1985] using kinetic bleaching data and computer modelling. These and other laboratory investigations [Liebergott et al., 1984; Reeve et al., 1985] have indicated that improved mixing can reduce chemical use in the bleach plant while maintaining or increasing pulp quality. CHAPTER 1. MIXING PULP SUSPENSIONS 23 1.5.3 M i l l E x p e r i e n c e The benefits identified in the laboratory studies have been borne out in mill situations. As early as 1973 Elliot and Farr [1973] reported substantial chemical savings when a Wobble plate mixer was replaced by a Fiscalin mixer on pulp chlorination. Additional reports of chemical savings appeared in successive years as mills improved their mixing systems and installed newer more efficient mixers. A summary of these reports is given in Table D.2. More recently, substantial chemical savings have been reported following the proliferation of high-shear mixers on C and D stages. A recent survey [Berry, 1987] found that typical chemical savings were between 7-8 kg chlorine/tonne pulp and 2-2.4 kg chlorine dioxide/tonne pulp. 1.5.4 M i x i n g R a t e The above discussion has focussed primarily on the effect of final mixture quality on pulp bleaching. However, the rate at which mixing quality is achieved is also important [O'Brien, 1975]. If mixing is slow compared with the effective bleaching reaction rate, the deleterious effects discussed above will occur even if acceptable mixing quality is eventually achieved. To assess the potential impact of the mixing rate we must first examine the various bleaching reaction rates. Bleaching chemicals are often added in gaseous form to pulp suspensions resulting in three phase reacting systems where the rates of dissolution, diffusion and chemical reaction all combine to determine an overall effective bleaching rate. While kinetic equations may be written that include each step in the reaction scheme [Levenspiel, 1972, 1984], one step often effectively controls the reaction rate, allowing simplification of an otherwise complicated reaction mechanism. In many cases the overall reaction rate can be approximated using a simple first order rate equation. For example, despite the more complicated reaction mechanisms discussed in section 1.5.1, delignification can CHAPTER 1. MIXING PULP SUSPENSIONS 24 Table 1.5: Relative mixing rates in common pulp mixers. T r / r m Mixer Type Bleaching Chemical Cl2 C102 o2 CST 6.0 x 10- 2 0.39 4.6 Static 4.5 29 350 High-Shear 180 1.2 x 10 3 1.4 x 10 4 be expressed as ( u i ) where [L] represents the lignin concentration. We can assign a characteristic time scale for delignification, TT, using rT = 1/jfc (1.12) Representative overall bleaching reaction rates have been determined using Equa-tion 1.11 and available kinetic data for the rapid init ial phase of pulp chlorination [Ackert, 1973; Karter, 1968; Russel, 1966a], bleaching with chlorine dioxide [Axegard, 1980], and oxygen bleaching [Evans et al., 1979; Olm and Teder, 1979; Hsu and Hsieh, 1988]. The rate of mixing is characterized by r m , the time required to produce a mixture of a specified quality. Mixing times are unavailable except for CSTs, but we can crudely estimate the mixing time by equating it to the mixer residence time and assuming that equal mixture quality is achieved. Based on this assumption, r r / r m has been estimated for the major bleaching reactions in common mixers, as shown in Table 1.5. Three cases are of interest: 1. Mixing occurs much faster than the effective reaction rate, r r / r m >^ 1: Here mixing has achieved homogeneity before chemical reaction has proceeded to any extent. The overall bleaching rate is therefore governed solely by the effective CHAPTER 1. MIXING PULP SUSPENSIONS 25 chemical reaction rate with the efficiency of bleaching determined by the quality of mixing achieved. A further increase in mixing rate would not improve pulp bleaching. Bleaching with chlorine dioxide and oxygen in static and high-shear mixers appears to be in this category. 2. Mixing and reaction proceed at much the same rate, i.e. rrJTm ~ 1: Here both mixing and reaction kinetics determine the rate and quality of bleaching. 3. Reaction occurs much faster than mixing, r r / r m <C 1: Here mixing is slow com-pared to the effective reaction rate. Consequently, the efficiency of pulp bleaching is determined by the rate at which mixing proceeds as well as the quality of the final mixture. The effect of slow mixing on pulp quality is similar to that of a poor final mixture. In this case, more rapid mixing would improve bleaching. As shown in Table 1.5 this criterion applies to chlorination in CSTs. The effect of in-creased mixing rate may account for some of the observed benefits of high-shear mixing in pulp chlorination [Reeve et ai, 1985]. Even if the ultimate mixture quality is not greatly improved, the faster rate at which it is achieved improves bleaching. 1.6 M i x i n g G a s e s i n t o P u l p S u s p e n s i o n s Bleaching chemicals are often added to pulp suspensions as gases. The gases can contribute substantially to the total suspension volume in certain situations. This has a number of important consequences for mixing and bleaching processes. Firstly, the suspension rheology can be dramatically altered, and this influences the quality of mixing achieved in the mixer. The bubble surface area created in the mixing process influences the rate of chemical dissolution and ultimately the reaction rate. Where rapid dissolution does not occur, either due to gas-side mass transfer resistance, low gas solubility or insufficient water in the suspension, a gas phase remains after mixing CHAPTER 1. MIXING PULP SUSPENSIONS 26 ceases. As the gas is approximately one thousand times less dense than the fibre and liquid phases, care must be taken to ensure that the mixture does not segregate. Under typical bleaching conditions it is possible to estimate the volume of gas that persists in a pulp suspension given the amount of water in the suspension and the gas solubility. In pulp chlorination 6-7% chlorine is added to the pulp on a weight basis. In both low (3% C m ) and medium (10-12% C m ) consistency chlorination there is sufficient water available to dissolve all the chlorine. However, dissolution takes a finite time and gas bubbles may persist after the mixing has stopped. An initial investigation into the dissolution rate of isolated chlorine bubbles in stagnant unbleached pulp suspensions has shown that approximately one minute was required for a chlorine bubble 1.7 mm in diameter to dissolve [Annau, 1984] (See also Appendix I). In the case of oxygen bleaching, the low solubility of oxygen in water leaves a substantial gas phase after mixing which exists throughout the bleaching reaction. In either case, in order to maximize mass transfer from the gaseous phase it is important to create and maintain as much gas surface area as possible. This requires the generation of small, well distributed gas bubbles in the suspension, and this is promoted by high shear forces and turbulence in the mixer. Hinze [1955] proposed a simple model to determine if a bubble was stable in a shear field. He postulated that the total local shear stress imposed by the continuous phase would act to deform the bubble. If the imposed stress exceeded the counterbalancing surface tension forces, the bubble would rupture producing smaller bubbles. For a gas/liquid or l iquid/l iquid system this criterion can be written [Clift et ai, 1978] as: This model predicts that a critical or maximum bubble size would exist for any system. Hinze [1955] gives the following correlation to predict the drop size below which 95% (1,13) CHAPTER 1. MIXING PULP SUSPENSIONS 27 of a dispersed liquid volume would be found under conditions of turbulent flow, i.e. where e m is the energy dissipation rate per unit mass within the system. For gas dispersion in a static mixer, the following correlation [Al-Taweel and Walker, 1983] for the Sauter mean drop diameter, rf32, is given: As the flow rate is increased the energy dissipated increases and bubble size decreases. The mixture must be maintained after mixing ceases. After the forces that created the bubble surface area are removed, the bubbles may coalesce unless prevented from doing so. In low consistency suspensions, bubbles may become trapped between fibres and prevented from coalescing. In medium consistency suspensions, where a substantial gas phase may persist, a stable foam-like system can be formed. 1.7 M e a s u r e m e n t o f M i x i n g Q u a l i t y Assessment of mixing quality is a difficult task. The most common methods are indirect and are based on measurement of product quality at the end of the process. In pulp bleaching, for example, residual chemical content, pulp brightness, and pulp viscosity can be readily measured. If they are poorer than expected when compared to known well-mixed cases the mixing quality may be suspected. However, factors other than mixing also affect product quality, and therefore direct methods to assess mixing quality are desirable. On-line devices to assess mixing in pulp suspensions are not available. An attempt was made to utilize an existing on-line brightness sensor for this purpose and is discussed in Appendix K. (1.14) = 0.397V1 - 0 . 4 3 (1.15) D We CHAPTER 1. MIXING PULP SUSPENSIONS 28 1.7.1 D i r e c t M e a s u r e m e n t o f M a c r o s c a l e M i x i n g The most common method of assessing macroscale mixing is by injection of a step or pulse tracer at the mixer entry and measurement of the tracer distribution at the mixer exit as a function of time. The resulting residence time distribution curves can then be compared with various models. This permits quantification of the mixer's ability to attenuate incoming fluctuations as well as identification of the existence of short circuiting or dead zones within the mixer [Cholette and Cloutier, 1959; Levenspiel, 1972]. To quantify macroscale mixing in pulp suspensions, a popular technique has been the injection of a tracer into the pulp suspension followed by sampling at some conve-nient location downstream, usually the top of the bleaching tower [Torregrossa, 1983; Kolmodin, 1984; Bergnor et al., 1985; Breed, 1985]. Another technique employs in-jection of a radioactively labelled tracer with the bleaching chemical and its detection downstream [Kuoppamaki, 1985]. A simpler technique uses the temperature profile around the mixer discharge pipe to identify steady-state macroscale variations for exothermic bleaching reactions [Torregrossa, 1983; Pattyson, 1984; Sinn, 1984]. In most cases mixing is quantified using an index based on the weighted standard de-viation of the measured variation over the mean. However, Torregrossa [1983] used the charge deviation or percent deviation from the average charge, while Sinn [1984] used the temperature profile around the mixer. Whatever the technique used, sizeable macroscale variations exist after pulp mixers as shown in Table 1.6. These data also show that macroscale mixing can be significantly improved by the replacement of peg and tower mixers by high-shear mixers. This observation seems to contradict the ear-lier statement that high-shear mixers cannot achieve macroscale mixing. However, the improved macroscale mixing occurs due to the reduction in mixing load resulting from CHAPTER 1. MIXING PULP SUSPENSIONS Table 1.6: Macroscale mixing quality of pulp mill mixers. Investigator Measurement Mixer Type and Mixing Index Method and Test Conditions Mixing Index (%) Torregrossa Li thium tracer 'Fluidizing' mixers 5-10 [1983] and temperature Single shaft 20-40 profile, In-tower radial 40 Charge Deviation Static 40-60 Kolmodin Lithium tracer, Tower mixers 26-50 [1984] s/x Kamyr M C 2-5 Sinn [1984] Temperature Peg mixer ±4°C profile Kamyr M C uniform Breed [1985] Chemical tracer, Ingersoll-Rand M C s/x before modifications 53 after modifications 6 Bergnor et al. Lithium tracer, Tower mixer 74-14 [1985] s/x 2 Kamyr M C 6-8 Kuoppamaki Radioactive tracer, Static Mixer axial: 0.5 [1985] s/x radial: 12 CHAPTER 1. MIXING PULP SUSPENSIONS 30 better chemical addition in the new mixers, akin to the change in mixing load illus-trated in Figures 1.2(a) and (b). Direct evidence of this comes from Breed [1985] who demonstrated that the macroscale mixing efficiency of an Ingersoll-Rand M C mixer could be substantially improved by optimizing the point of chemical addition. The measurement of macroscale mixing in a mil l situation can be used to estimate the potential benefits available through improved mixing. This is accomplished in two steps. First, the quality of the mill mixing must be determined. By adding a non-reacting tracer to the bleaching chemical prior to contacting with the pulp suspension, the quality of macroscale mixing can be determined independant of chemical reaction. Second, the bleaching response of the pulp must be determined at various chemical dosages, for example by using Torregrossa's charge deviation method. Once this infor-mation is known, it is a relatively simple matter to estimate the benefits available from improving mil l mixing. In the absence of specific information on a particular pulp, a relative estimate can be made by referring to previous studies. 1.7.2 D i r e c t M e a s u r e m e n t o f F i b r e - S c a l e M i x i n g Fibre-scale mixing has been measured by Paterson and Kerekes [1985] using a micro-sampling technique. This test involved removing 5 /zL samples of the aqueous phase at 2 mm intervals from chlorinated low consistency pulp suspensions. The free chlorine in each sample was determined and a concentration profile obtained. These data were normalized using the average chlorine concentration and used to calculate the intensity of segregation, //„. This parameter gives the standard deviation of the chlorine distri-bution in the suspension at a spacing of 2 mm and therefore is an index of fibre-scale uniformity. In most cases multiple determinations of I, were made, and the root mean square average was reported (1.16) CHAPTER 1. MIXING PULP SUSPENSIONS 31 Table 1.7: Fibre-scale mixing quality of pulp mil l chlorination mixers. Mi l l and Mixer Type Intensity of Segregation, / „ I, Range of Tests Good Lab Mixing 0.0 Poor Lab Mixing 0.67 Mi l l A , in-line static 0.13 0.12 - 0.14 Mi l l B, two chamber C S T 0.16 0.0 - 0.23 Mi l l C , in-line static 0.16 0.09 - 0.18 Mi l l D, CST + static - 0.03 - 0.11 Mi l l E l , CST 0.12 0.0 - 0.30 Mi l l E2, two static mixers 0.07 0.0 - 0.11 Mi l l F, two static -f mechanical 0.12 0.0 - 0.22 Mi l l G , in-line static 0.14 0.0 - 0.24 Mi l l H, two static mixers 0.55 0.23 - 0.83 Mi l l I, in-line static 0.36 0.09 - 0.58 Mills A - E 2 [Paterson and Kerekes, 1986]. Mil ls F-I [Teodorescu and Liebergott, 1987-8]. The results obtained by Paterson and Kerekes [1986] and later by Teodorescu and Liebergott [1987-8] are shown in Table 1.7. Most mills have I, values in the range 0.07-0.16. However, in two mills tested, values substantially higher than this average were found. Although this technique is time consuming, it permits comparison of fibre-scale mixing quality in low consistency chlorination and can identify those mills with particularly poor fibre-scale mixing. At this point, however, the relationship between these mixing indices and bleaching quality has not been established. 1.7.3 E s t i m a t e s o f M i x i n g Q u a l i t y The difficulty in applying even simple methods to measure mixing quality in pulp suspensions has encouraged the use of indirect methods to compare mixers. These methods are based upon easy-to-measure variables and the rheological properties of pulp suspensions discussed earlier. While only approximate, they are often the only means available for a quick indication of how good mixing is likely to be. CHAPTER 1. MIXING PULP SUSPENSIONS 32 1.7.3.1 M i x i n g P o w e r As discussed earlier, the power dissipated per unit volume, e, is related to the extent and intensity of relative motion within a fluid. Because the power is dissipated in small-scale fluid motion, it can be used as an indicator of small-scale mixing, specifically the rate of fibre-scale and microscale mixing. Indeed, the newly emerging mechanism of micromixing predicts that "all devices operated at the same power per unit volume will generate the same rate of micromixing" [Bourne, 1983]. This of course assumes uniform power dissipation throughout the mixer. While this may be true in the mixing zone in high-shear mixers, it is not the case in all mixers, such as the CST mentioned earlier. Thus, the distribution of the power dissipation throughout the suspension is as important as its total. As an example, enormous power could be used to mix and remix a restricted region of a mixer while other regions were left unchanged. With the understanding that it must be well distributed, power dissipation is a useful parameter to estimate the rate of small-scale mixing. Some typical values of power dissipation for common pulp mixers are given in Table 1.8. The usefulness of power dissipation can be illustrated by several examples. First, one can estimate the ability of a mixer to achieve the "fluidization" levels reported by Gullichsen and Harkonen [1981]. Second, power dissipation can be used to estimate the relative mixing rates in the various mixers. On this basis the Ingersoll-Rand, Kamyr, and Sunds M C mixers all generate approximately the same rate of fibre-scale mixing. Conventional peg mixers have power dissipation rates two orders of magnitude lower than the high-shear mixers and consequently lower mixing rates. 1.7.3.2 M i x i n g E n e r g y Power dissipation takes place over time and yields energy dissipation. Thus, the energy expended in mixing per unit mass of suspension is an indicator of the amount of relative Table 1.8: Comparison of mixers used in pulp bleachingf. Mixer Type Consistency Operating Range (Cm, %) Residence Time in Working Zone (s) Maximum Shear Rate in Mixer Working Zone Cs"1 ) Power Dissipation in Mixer Working Zone (W/m 3 ) Energy Expenditure in Mixer (MJ/ t pulp) CST 2-3 150-400 600 5-9 Static 2-3 3-5 3.0 x l O 4 4 Hand Lab Mix ing! 3 180 2.0 x l O 4 120 10 180 1.0 x l O 4 250 M C Lab High-Shear 10 10 3.0 x l O 3 1.8 x l O 6 180 Beloit-Rauma 10 2-4 4.0-6.0 x l O 3 4.0 x l O 5 13-28 Ingersoll-Rand 9-16 ~0.05 0.6-1.0 x l O 4 5.5 x l O 7 8-15 Kamyr M C 9-14 0.2-0.9 0.2-1.0 x l O 4 0.55-1.2 x l O 7 14-43 Peg 10-12 10-12 0.8-1.1 x l O 5 11-15 Sunds M C 9-14 0.025-0.05 1.0-5.0 x l O 3 0.39-1.1 x l O 8 9-18 A B N HC 20-35 60-90 Sunds HC 25-45 70-110 f Information is based on mill data and manufacturer's literature. | Power and energy input in hand laboratory mixing was determined by measuring the temperature rise in the pulp sample during mixing. CHAPTER 1. MIXING PULP SUSPENSIONS 34 motion and therefore the degree of mixing that has occurred. Often, it is the only read-ily available parameter to estimate mixer performance. Typical energy expenditures in various pulp mixers are included in Table 1.8. The values for hand laboratory mixing were determined by measuring the temperature rise of a pulp sample during mixing, while mill data and manufacturers' promotional information were used to determine values for the other mixers. Several interesting comparisons may be made using these data. First, the energy for hand laboratory mixing and batch laboratory high-shear M C mixing [Reeve et al., 1985] are about an order of magnitude greater than the energy expended in mill mixers at the same consistency. This may in part account for the fact that laboratory bleaching is generally better than that achieved in the mil l . Second, while the energy input for mill M C mixers ranges from 8 to 43 MJ/tonne pulp for a consistency range of 9 to 16%, the energy at the lower limit is approximately the same, 11±2.5 MJ/tonne pulp. This agreement exists despite the fact that mixing times in these mixers vary over almost three orders of magnitude. In comparing the energy expended in mixing, it should be noted that equal energy expenditure in mixing does not necessarily imply equal mixing quality. For example, a mixer operating at a high rate of power dissipation for a short period of time may be more effective than a mixer having lower power dissipation applied over a longer time, with equal total energy expenditure in the two cases. This is particularly true for fast chemical reactions where mixing rate is important. However, when used with caution, the energy expended per unit mass of pulp in mixing is a useful parameter for comparing and characterizing alternative mixers. 1.7.3.3 Shear Rate The disruption of pulp networks requires the application of a certain shear force within the suspension. Although a number of factors, including suspension rheology and mixer CHAPTER 1. MIXING PULP SUSPENSIONS 35 design, determine the shear stress that can be created within the suspension, a param-eter which can be readily estimated is the maximum shear rate imposed by the mixer. For rotating machinery this is readily calculated by dividing the rotational velocity at the vane tip or disk by the gap width over which the force is being applied. In a given mixer, the imposition of larger shear rates should result in creation of greater stress within the suspension. However, differences in mixer design do not permit accurate comparison between mixers on this basis alone. 1.7.3.4 M i x e r R e s i d e n c e T i m e Mixer residence time gives an indication of the pulp's exposure to power input. While it does not give information of the residence time distribution within the mixer, it can be used to provide a rough estimate of the degree of macroscale mixing possible. 1.8 C r i t e r i a f o r G o o d M i x i n g While our knowledge of mixing in pulp suspensions is incomplete, some simple concepts that promote good mixing are apparent: 1. The mixing load should be minimized. This involves ensuring that the flow of chemical and pulp suspension to the point of mixing are as uniform as possible. In addition, the location and number of chemical injection points should be chosen to minimize the distance over which chemical and pulp fibre must be transported in the mixer. 2. Mixing must occur at all scales of importance. As there exist both large and small-scale non-uniformities in the system, mixing must be targetted at the most important scale. Macroscale mixing requires a distribution of residence times, while fibre-scale and microscale mixing require that small-scale relative motion be created within the suspension. The former requires backmixing caused by CHAPTER 1. MIXING PULP SUSPENSIONS 36 the mixer residence time distribution, while the latter requires the imposition of sufficient shearing forces to disrupt the network structure. Where practical, large-scale variations should be removed prior to small-scale mixing. 3. Mixing should occur at such a rate that bleaching performance is optimized. 4. Mixture stability must be maintained. In cases where gaseous bleaching chem-icals persist for some time after chemical injection, forces that would separate gas bubbles from the suspension must be avoided until dissolution has been com-pleted. 5. In higher consistency pulp suspensions (>18-25% C m ) where fluid-like motion is difficult to achieve, chemicals should be contacted with the maximum exposed fibre surface possible. 6. Sufficient time must be permitted for diffusion to complete mass transfer in the subsequent bleaching residence time tower. It may not be practical to achieve all the above criteria in one mixer. However, by designing the overall mixing system (injection, mixing, residence time, and control) the desired mixing quality can be attained, resulting in efficient bleaching with optimum chemical use and maximum pulp quality. 1.9 Research Objectives From the proceeding literature review it is apparent that much work remains to under-stand most aspects of pulp mixing. A number of areas are identified below and were examined as part of this project. 1. The creation of motion within the pulp suspension is a prerequisite to effective mixing and first requires the imposition in the suspension of forces greater than CHAPTER 1. MIXING PULP SUSPENSIONS 37 the network yield stress. The strength of pulp networks has been determined primarily for low consistency suspensions where the gas phase is negligible. It would be valuable to determine suspension yield stress over a wider range of conditions and where a substantial gas phase existed. 2. The dynamic behaviour of a pulp suspension is very important in mixing. How-ever, pulp suspension rheology is complex and little work has been carried out on medium consistency suspensions. In particular, the study of medium con-sistency pulp suspension behaviour at high shear rates is needed to more fully understand new technology in the pulp and paper industry that depends on flow in this consistency range, including but not limited to M C mixing. 3. The quality of mixing necessary to achieve optimal bleaching is not known. Fur-ther fundamental information is needed on the reaction and dissolution of gaseous chemicals in pulp suspensions, and the diffusion of aqueous chemicals through pulp suspensions of various mass concentrations. 4. Mixing assessment, particularly in the mil l environment, is difficult. A simple effective method to evaluate mill mixing would be useful. C h a p t e r 2 S t r e n g t h o f F i b r e N e t w o r k s 2.1 I n t r o d u c t i o n Before motion can be initiated in a pulp suspension, whether it is to mix, transport or disperse the suspension, external forces sufficient to overcome fibre network forces must be applied. While there is an abundance of information available on the strength properties of low consistency pulp suspensions, only a few investigations have studied fibre network strength at medium and high consistencies. The literature shows that network strength varies substantially from study to study, ostensibly due to differences in measuring techniques and the properties of the pulps tested. In the last decade interest in M C suspension rheology has grown as pulp suspension unit operations began to be carried out in this range. However, the lack of research on M C pulp properties requires that extrapolation be made from information available in the L C range. This procedure could result in large estimation errors. Indeed, the measured strength of pulp suspensions at ultra-high consistency (dry floes and wet webs), can be substantially different than that predicted by extrapolation from L C data. Thus accurate experimental data are needed. An attempt should also be made to relate the strength differences found between various pulp types to individual pulp fibre properties. Indeed, it would be desirable to be able to estimate pulp network strength from knowledge of fibre properties and suspension concentration alone. 38 CHAPTER 2. STRENGTH OF FIBRE NETWORKS 39 2.2 L i t e r a t u r e R e v i e w 2.2.1 S t r e n g t h o f P u l p F i b r e N e t w o r k s The reasons for the high strength of pulp fibre networks have attracted considerable attention over the years. Although fibre flocculation was initially treated as a colloidal phenomenon, it is now recognized that fibre suspensions form coherent networks pri-marily due to physical forces produced by the entanglement of individual fibres. Wahren [1964] gives the following explanation for the formation of coherent fibre networks: . . . When agitation ceases, the fibres tend to regain their original unstrained shape. However, if there are many fibres per unit volume, they cannot straighten out freely but will come in contact with other fibres. A fraction of the fibres will come into contact with so many others that they will come to rest in strained positions, and forces will be transmitted from fibre to fibre. These fibres become interlocked by normal and frictional forces, constituting a fibre network where forces can be transmitted through the fibres and from fibre to fibre. In other words, fibre networks are coherent because of internal stresses. Researchers have measured the strength properties of pulp fibre networks using many different experimental techniques, most of which were conducted on low (0-6% C m ) consistency pulp suspensions. Kerekes et al. [1985] have reviewed many of these inves-tigations, and have grouped them into three categories according to the type of test conducted: Tensile strength of pulp networks. The point at which a pendant column of pulp, extruded from a tube into a water bath, ruptured under its own weight has been used as a measure of pulp network tensile strength. Tests have been conducted at consistencies between 0.2 and 1.3% Cm. Quasi-static shear strength. The measurement of the shear strength of pulp networks has been determined in viscometer-like devices by imposing increasing strain on the network using a variety of rotors. Not only did the conditions of the tests CHAPTER 2. STRENGTH OF FIBRE NETWORKS 40 vary considerably, but the point of network failure was interpreted differently by different investigators. For example, some measured a "disruptive shear stress", the stress required to permanently disrupt the network, while others measured the "ultimate shear stress", the maximum shear stress sustainable by the net-work. Most experiments were made on low consistency suspensions although some ventured into the M C range. Dynamic network strength. When a pulp suspension flows through a smooth-walled pipe, a number of flow regimes are possible. As the flow velocity of the pulp suspension increases, the fibres move away from the pipe wall, leaving a clear water annulus between the wall and the fibre plug. As the velocity of the fibre plug increases, the shear stresses in the water annulus eventually become sufficient to tear fibre floes and individual fibres from the plug surface. At this point, the shear forces in the annular region are sufficient to overcome the forces holding the fibres in the network, and can be used as a measure of the network strength. Due to the nature of this test, only low consistency suspensions have been characterized using this method. Despite the wide range of test procedures used to determine network strength, the network strength for any given pulp in any given test can be fitted to a simple power law equation r = aCj (2.1) where r is the strength property measured, Cm is the suspension mass concentration (in percent), and a and b are fitted constants. These parameters depend on many factors, including the test procedure, the pulp type and degree of pulp treatment (beating) prior to testing. Past work has found that pulp network strength depends greatly on Cm, with values of a between 1.18 and 24.5, and values of b between 1.26 and 3.02 [Kerekes et al., 1985]. CHAPTER 2. STRENGTH OF FIBRE NETWORKS 41 Theoretical work on three-dimensional fibre networks was conducted by Meyer and Wahren [1964]. They developed a mathematical model of fibre network structure and used it to predict the effect of various parameters on network properties. This work predicted that the shear modulus of a fibre network would be proportional to the elastic modulus of the fibres and would vary as the fibre volume concentration raised to a power between 2 and 2.6, depending on the fibre aspect ratio. These predictions have been supported by experiment. Thalen and Wahren [1964a] and Bergman and Takamura [1965] found that the shear modulus of a fibre network was proportional to the modulus of elasticity of the fibres in the network. The abundant data on network strength [Kerekes et al., 1985] support the strong dependence of network strength on suspension concentration, although the measured dependence varies over a wider range than specified by Meyer and Wahren. 2.2.2 Strength of Man-Made Fibre Networks The rheology of man-made fibre suspensions can greatly aid our understanding of pulp fibre suspension behaviour. As man-made fibres have uniform dimensions and are not fibrillated, they can be well characterized and consequently make ideal model suspen-sions. The literature dealing with the rheology of suspensions of rod-like particles has recently been reviewed by Ganani and Powell [1985]. One of the issues discussed was the existence of a suspension yield stress. While a number of the reviewed studies reported the existence of a yield stress, most did not observe one. This led Ganani and Powell to conclude that the existence of a yield stress was an "open issue". However, one possible explanation for the absence of a yield stress in the majority of investigations can be found in the fibre network theory of Meyer and Wahren [1964]. According to this theory, when the suspension concentration falls below the sediment concentration 1, the number 1The concentration of the sediment following gravitational sedimentation from a dilute suspension. CHAPTER 2. STRENGTH OF FIBRE NETWORKS 42 of fibre/fibre contacts falls below three and a continuous network cannot be formed. It therefore would not have a yield stress. In experimental work on Perlon, Teflon and glass fibre networks, Thalen and Wahren [1964b] were unable to measure a network strength at suspension concentrations lower than the fibre sediment concentration — a finding that supports Meyer and Wahren's theory. Examination of the investigations reported by Ganani and Powell using the criterion for network formation given by Meyer and Wahren shows that those tests where a yield stress was not observed were conducted under conditions where a yield stress would not be expected. However, some researchers maintain that "the yield stress only defines what cannot be measured" and that "if a material 'flows' at high shear stresses it will also flow, however slowly, at low stresses" [Barnes and Walters, 1985]. These researchers maintain that given appropriate instrumentation, a finite viscosity can always be measured. Those investigations that did report a network yield stress are summarized in Ta-ble D.4. Analysis of these investigations show that, as in the case for pulp fibre suspen-sions, the yield stress increases exponentially with increasing suspension concentration, with exponents commonly in the range of 2-3. A thorough investigation of the characteristics of nylon fibre suspensions was con-ducted by Horie and Pinder [1979] in a concentric cylinder viscometer using profiled rotors. Consistent with other investigators, they measured a network yield stress which was found to be very dependent on suspension volume concentration. For example, for 5 mm nylon fibres in a matrix of 10% polyethylene glycol in water with dextran and 1.0 mole/1 NaCl ry = 3.11C V 3- 7 3 r 2 = 0.984 (2.2) where Cv is in percent and r y is in Pascals. The yield stress increased with increasing fibre aspect ratio and increasing salt concentration, while the age of the suspension be-fore testing was also found to affect greatly the measured yield stress. Tests conducted CHAPTER 2. STRENGTH OF FIBRE NETWORKS 43 immediately after suspension preparation had yield stresses approximately one half that of tests conducted after the suspension had been allowed to age in the viscometer 15-20 hours prior to testing. Maximum strength was obtained after approximately 20 hours, and most tests were conducted on suspensions aged overnight. Although Horie and Pinder made their measurements using a 10.9 mm wide gap, the range of fibre lengths measured (0.987-6.72 mm) was such that in all cases a negligible wall effect could not be assumed. A study by Morrison and Harper [1965] investigated wall effects in Couette flow of non-Newtonian suspensions where a fibrous solid phase (cellulose fibres, I ~ 0.5 mm, d ~ 30 fim) was suspended in a liquid. They found that the yield stress increased as the gap width decreased and noted that Visual observations provide an explanation for the trend toward increasing yield stress with decreasing gap width. Wi th initiation of shear, the fluid tended to break up into clumps of fibres 1 to 4 mm in diameter. Since these clumps must move past each other for shear to take place, the width of the gap controls the maximum clump size. The higher yield stress for the smaller gaps is thus caused by the greater stress necessary to form the smaller clumps. The work on man-made fibre suspensions by Thalen and Wahren [1964b] showed that the fibre aspect ratio, and not the fibre length alone, was the dominant factor determining both the sediment concentration and the shear modulus of the fibre net-work. Their data suggested that the network shear modulus was proportional to the fibre modulus of elasticity. The effect of fibre size distribution on suspension properties has not been studied [Ganani and Powell, 1985]. 2.2.3 T e n s i l e S t r e n g t h o f F i b r e F l o e s Two investigations have measured the tensile strength of individual fibre floes. Garner [1986] measured the tensile strength of bleached kraft and refiner mechanical pulp floes at high solids content ( C m = 60-95%). For each pulp, floe strength was fitted to an CHAPTER 2. STRENGTH OF FIBRE NETWORKS 44 equation of the form O-T = apt (2.3) where cr r is the tensile force in Pascals, p\, the bulk density in kg /m 3 and a and b are constants. The bleached kraft pulps gave exponential values of 2.3 while the re-finer mechanical pulps gave exponential values of 2.7 and 3.3. There was wide scatter between floe strengths determined in successive tests, which Garner attributed to non-uniformities within the floes and experimental difficulties handling the weak networks and measuring floe dimensions. Garner found that all his data could be fitted equally well by a single equation <rT = 5.8 x H T 4 [(lpb0A)/Crn}2-24 (2.4) where I is the fibre length, 0 the aerodynamic specific surface of the pulp suspension, A the fibre aspect ratio, and C m the solids content of the fibres (in percent). Soszynski [1987] measured the tensile strength of coherent, nearly spherical, nylon floes produced in an inclined rotating cylinder. Floe tensile strength was determined while the floes were supported in an aqueous sucrose solution having the same density as the nylon fibres. The experimental data were fitted to <rT = aCvb (2.5) where cr is the floe strength in Pascals, Cv the volumetric concentration of the floe in percent, and a and b are fitted constants. Values of the exponent b varied between 2.02 and 3.31. As with Garner's experiments, there was wide scatter between successive strength determinations. Soszynski developed a comprehensive model to describe network failure under tensile loading. The model is based on the assumption that the tensile strength arises due to fibre bending forces developed at fibre/fibre contact points, and gives 3 d2 4 aT = — sin7 kckdkf (*dE — 8max Cv nc (2.6) CHAPTER 2. STRENGTH OF FIBRE NETWORKS 45 where cry is the tensile breaking strength of the fibre floe, 7 the average angle between the fibre axis and a plane in a random three-dimensional network, kc, kj, kf are constants describing the fraction of fibres taking part in the tensile strength, fi^ is the coefficient of dynamic friction, E the modulus of elasticity, I and d the fibre length and diameter, respectively, 6mas the maximum fibre deflection, Cv the volumetric concentration of the suspension, and nc the number of fibre contacts. This model had limited success predicting the pre-exponential factors measured experimentally. In part this can be attributed to difficulties in determining the many constants in Equation 2.6. 2.2.4 T e n s i l e S t r e n g t h o f W e t W e b s In the early stages of the papermaking process, pulp fibres are formed into wet webs which are two-dimensional pulp networks. The ability of the wet web to withstand forces imposed in drainage, couching, drawing and pressing operations depends on its tensile strength. Consequently wet web strength and the factors that affect it have re-ceived considerable study. However, wet web strength is commonly measured in terms of breaking length or line loading, and must be converted into units of stress for compar-ison with measurements of pulp network strength. This is not always possible because web thickness or sheet density are not always measured. However, several researchers have recorded this information, and thus some comparison of network strength with wet web strength are possible. Data on wet web strength were obtained from studies by Robertson [1959] and Lyne and Gallay [1954a, 1954b] and fitted to the equation <rT = aCj (2.7) Values of the exponent b were found to be 0.97,2.04 and 2.86 in the three studies. CHAPTER 2. STRENGTH OF FIBRE NETWORKS 46 2.2.5 S u m m a r y o f P r e s e n t K n o w l e d g e The preceding sections have reviewed major findings on the network strength of pulp and man-made fibre suspensions. While there has not been complete agreement among all investigations, due in part to the wide variety of test conditions and fibre types studied, a general picture of the factors that affect the strength of these suspensions emerges. Experiment and theory have shown that fibre suspensions have measurable network strength which depends upon fibre concentration and fibre properties. Over a very wide range of conditions, network strength in both shear and tensile modes has been found to vary with suspension concentration raised to powers of between approximately 1.5 and 3.5. Other experiments have shown that fibre network strength also depends on the fibre elastic modulus and fibre aspect ratio. Perhaps some agreement should be expected between all mesurements of network strength, for in all cases network strength arises from interaction between fibres in the network. Figure 2.1 gives a graphical compilation of many of the studies on pulp network strength presented in the literature. 2.3 E x p e r i m e n t a l 2.3.1 O b j e c t i v e One objective of this research was to measure the yield stress of pulp fibre networks over a wide range of suspension mass concentration. Of particular interest was the medium consistency range where a substantial gas phase is present and expected to be important. A number of commercial pulps and man-made fibre suspensions were examined. An attempt to explain network yield stress in terms of fibre and suspension properties was made. CHAPTER 2. STRENGTH OF FIBRE NETWORKS Tensile Methods _Qu a s i_-S t a tj c _M et h o d s _ Dynamic Methods A Wet Web Strength o Strength of Fibre Floes ' 't///',/ • A A A A A O O i i i i i i i i J I I I I I I I i i i i i i i 10" io° id Mass Concentration, C m (%) lCf Figure 2.1: Literature data on the strength of pulp fibre networks. CHAPTER 2. STRENGTH OF FIBRE NETWORKS 48 2.3.2 E q u i p m e n t The wide range of shear stresses to be determined in this research required that two instruments, a Haake RV12 Rotovisco concentric cylinder viscometer and the pulp fluidizer (a concentric cylinder device capable of operating at high torques and described in detail in Appendix A) , be utilized with a wide range of rotors. The shear stress at the wall of a rotor is given by T = 2 ^ L <2-8> where T is the torque acting on the rotor and R and L are the radius and length of the rotor. The rotors were profiled, having lugs 2 that protruded from the surface, while the outer housings had baffles arranged at 60° intervals around the periphery. The rotor lugs and housing baffles prevented fibre slippage at the walls and imposed shear within the suspension. The RV12 rotors were hollowed out on the bottom so that air was trapped beneath them when lowered into the suspension. Thus only the measuring surface and the smooth sharp edge on the bottom of the rotor were in contact with the suspension. In order to minimize the effect of gap width on the shear stress measured, it was kept much larger than a fibre length, a minimum of 20 mm in tests made with the Haake viscometer (although it varied from rotor to rotor), and 50 mm in tests made with the pulp fluidizer. The geometry and calibration constants for the rotors and housings are listed in Tables A . l , A.2 and A.4. 2.3.3 F i b r e a n d S u s p e n s i o n P r o p e r t i e s A number of different pulp and synthetic fibres were studied in these experiments. Samples of semi-bleached kraft (SBK-1), stone groundwood (SGW-1) and thermome-chanical (TMP-1) pulp samples were obtained from MacMil lan Bloedel's Powell River mil l ; semi-bleached kraft (SBK-4) was provided by Canadian Forest Products' Howe 2In all cases R was measured to the tips of the rotor lugs. CHAPTER 2. STRENGTH OF FIBRE NETWORKS 49 Sound mil l . Nylon fibres were obtained from the Department of Chemical Engineer-ing at U B C , having originally been obtained as nylon threads (type 120) from E.I. du Pont de Nemours & Co. and cut into lengths by Fibretex Ltd. The nylon fibres had been used in previous investigations by Horie and Pinder [1979] and Soszynski [1987]. Spectra 900 (high tenacity, high modulus polyethylene and polypropylene) fibres were obtained from Allied Fibers. The pulp fibre suspensions were prepared with water. To obtain neutral buoyancy, the nylon suspensions were prepared with a 33% wt/wt solu-tion of sucrose in water, while the Spectra 900 fibres were suspended in a 19% wt/wt ethanol/water mixture. Fibre and suspension properties are summarized in Table 2.1. Appendix C gives relevant information concerning fibre and suspension properties and how they were determined. 2.3.4 P r o c e d u r e 2.3.4.1 S u s p e n s i o n P r e p a r a t i o n Pulp suspensions were prepared twelve hours in advance of testing from pulp samples obtained from the mill. The stone groundwood suspensions were beat for five minutes in a British Standard Disintegrator to improve suspension uniformity. The nylon and Spectra 900 fibres were thoroughly washed to remove surfactants used during manu-facture and then completely dried at 108°C before being made into suspensions. The nylon suspensions were prepared 24-48 hours in advance of testing using a 33% wt/wt sucrose/water solution having the same density as the fibres. A small quantity of ben-zethonium chloride (0.055 g/kg solution) was added to the sucrose solutions to prevent bacterial growth in the suspensions. The Spectra suspensions were prepared with a 19% wt/wt ethanol/water mixture having the same density as the fibres. Between tests all suspensions were kept in refrigerated storage at 4°C. TABLE 2.1: SUMMARY OF FIBRE AND SUSPENSION PROPERTIES F I B R E / S Y S T E M I D E N T I F I C A T I O N FIBRE PROPERTIES SOLUTION PROPERTIES FIBRE LENGTH <L>L (mm) FIBRE DIAMETER (mm) ASPECT RATIO WRV ( k g / k g ) E L A S T I C MODULUS ( P a ) F IBRE DENSITY (kg/m**3) SOL'N DENSITY (kg/m**3) V I S C O S I T Y a t 20' C ( P a . s ) NYLON, 1 mm 15 D e n i e r 1n a 3 3 % wt/wt s o l u t i o n o f S u c r o s e 1n Water 1 .22 0.0449 27.2 0.0769 1.76E09 1140 1 140 0.0039 NYLON, 2 mm 15 D e n i e r 1n a 3 3 % wt/wt s o l u t i o n o f S u c r o s e In Water 1 .89 0.0449 42. 1 0.0769 1.76E09 1140 1140 0.0039 NYLON, 3 mm 15 D e n i e r 1n a 3 3 % wt/wt s o l u t i o n o f S u c r o s e i n Water 3.45 0.0449 76.8 0.0769 1.76E09 1 140 1 140 0.0039 NYLON, 5 mm 15 D e n i e r 1n a 3 3 % wt/wt s o l u t i o n o f S u c r o s e 1n Water 5. 16 0.0449 1 15 0.0769 1.76E09 1 140 1140 0.0039 NYLON. 7 mm 15 D e n i e r 1n a 3 3 % wt/wt s o l u t i o n o f S u c r o s e 1n Water 7. 12 0.0449 159 0.0769 1.76E09 1140 1140 0.0039 SBK-1 1n W a t e r 2.37 0.03 79.0 1 .26 3.52E07 1500 1000 0.0010 SBK-2 m W a t e r 2.51 0.03 83.7 1 .26 3.52E07 1500 1000 0.0010 SBK-3 1n W a t e r 2.40 0.03 80.0 1 .26 3.52E07 1500 1000 0.0010 SBK-4 i n W a t e r 1 .94 0.03 64.7 1 .26 3.52E07 1500 1000 0.0010 SGW-1 i n W a t e r 0.61 0.03 20.3 0.84 9.23E08 1500 1000 0.0010 SGW-2 In W a t e r 0.61 0.03 20.3 0.84 9.23E08 1500 1000 0.0010 SPECTRA 9 00, 3.3 mm 1n a 19% wt/wt s o l u t i o n o f E t h a n o l In W a t e r 3.34 0.038 87.9 0.01 6.5 E10 970 970 0.0021 SPECTRA 9 00, 6.2 mm In a 19% wt/wt s o l u t i o n o f E t h a n o l In Water 6.15 0.038 162 0.01 6.5 E10 970 970 0.0021 TMP-1 m W a t e r 1 . 16 0.03 38.7 0.91 1.08E09 1500 1000 0.0010 UBK-1 i n W a t e r 1 .93 0.03 64.3 1 .26 - 1500 1000 0.0010 CHAPTER 2. STRENGTH OF FIBRE NETWORKS 51 2.3.4.2 M e a s u r e m e n t P r o c e d u r e s The Haake RV12 viscometer was used to determine the yield stress of fibre networks when the shear stress was less than 1225 Pa. The pulp fluidizer was used when the yield stress exceeded this value. A l l suspensions were tested at room temperature, which over the course of the RV12 experiments was 21.8 ± 1.6°C. H a a k e R V 1 2 R o t o v i s c o T e s t P r o c e d u r e : Tests made on the Haake RV12 were conducted as follows. Prior to a test, a sufficient volume of the fibre suspension was added to the housing so that, when lowered, the entire rotor measuring surface would contact the suspension while leaving at least 10 mm between the bottom of the rotor and the bottom of the housing. Despite the care with which the rotors were lowered into a fibre suspension, the fibre network was disrupted. At lower consistencies, particularly for the shorter fibred suspensions, the suspension immediately enveloped the rotor ensuring complete contact with the entire measuring surface. However, as suspension consistency was increased, the ability of the suspension to flow was reduced. Consequently some assistance was needed to ensure that the entire rotor surface contacted the suspension. This involved physically moving the suspension back into contact with the rotor. This was required for long fibred suspensions at higher mass concentrations, for example, for semi-bleached kraft samples above approximately 4% C m . A test was made by slowly increasing the shear rate, using the programmable con-troller of the Haake RV12, until a maximum torque or break point was observed on the x-y plotter (torque versus rotational speed). The maximum shear rate and ramp time were chosen to give a reproducible well defined yield torque, and are discussed further in Section 2.4.1.1. After the fibre suspension yielded, the test was stopped and the rotor removed from the suspension. The fibre suspension was then mixed and the rotor lowered for a further test. Typically, ten determinations were made for each test CHAPTER 2. STRENGTH OF FIBRE NETWORKS 52 condition. P u l p F l u i d i z e r Test P r o c e d u r e : Tests made with the pulp fluidizer were conducted as follows. A known weight of pulp was packed into the fluidizer housing and the lexan cover secured over the housing face. By means of a computer program (listed in Table B.2) the voltage to the controller regulating the motor speed was slowly increased in a linear manner. It was found that the shaft torque increased until the suspension yielded, after which the rotor moved continuously. The yield torque was determined by subtracting the torque at the break-away point from the friction torque determined separately. 2.4 Resu l t s and D iscuss ion 2.4.1 Y i e l d Stress 2.4.1.1 Y i e l d Stress De te rm ina t i on In measurements made with the Haake viscometer, the yield stress of a fibre suspension was determined from a plot of torque versus rotational speed. In a test, the shear rate was increased slowly from rest. As the rotor turned, torque increased, eventually reaching a point where it began to level off or drop. This maximum stress occurred after only 5-20° of rotation, as shown in Figure 2.2 for a 1.6% Cm semi-bleached kraft pulp. While no rotor movement should occur before the yield stress is attained in a classic system, the rotor movement can be explained by analogy to solid systems. A solid displays a number of characteristic regions of stress/strain behaviour. The first is the elastic region where stress is proportional to applied strain and deforma-tion is completely recoverable. However, if strain is continued past the elastic limit, deformation is not fully recoverable and plastic deformation occurs. If strain is contin-ued further the solid will yield. The yield point can be defined in a number of ways, CHAPTER 2. STRENGTH OF FIBRE NETWORKS 53 co I r o A 1 1 1 0 10 20 30 R o t o r D i s p l a c e m e n t , D e g r e e s Figure 2.2: Stress vs. rotor angular displacement for a 1.6% Cm semi-bleached kraft pulp (SBK-4) tested with the Haake RV12. Rotor M V I P , housing RVH1 . Rotor ac-celeration was 2.91 x 1 0 - 5 rad/s 2 . The various curves and symbols represent different tests conducted under identical conditions. CHAPTER 2. STRENGTH OF FIBRE NETWORKS 54 but a common definition is when elongation occurs without further increase in stress [Baumeister et al., 1978]. The stress/strain curves for pulp suspensions displayed solid-like characteristics as shown in Figure 2.2. When the rotor began to move, fibres next to the rotor surface moved. However, individual fibre motion was restrained by inter-action with adjacent fibres and stress was built up within the fibre suspension. Further angular displacement of the rotor increased stress until it reached the maximum level sustainable by the network. At this point the suspension "yielded", that is, further rotor displacement did not increase the stress. This stress maximum, observed in all tests, has been called the network yield stress, ry. The maximum shear rate and ramp time (which determine rotor acceleration) were chosen for each test so that a well defined break in the torque vs. rotational speed curve was observed. For low consistency suspensions characterized by lower network yield stresses, a slower acceleration was needed so that the break point in the curve was not masked by inertial effects of the measuring system. This practice is consistent with those used for determining fluid yield stresses [Schramm, 1981]. For example, the torque vs. rotational speed curve for a 0.8% C m semi-bleached kraft pulp is given in Figure 2.3. The point on the curve marked by the arrow was interpreted as the yield point and was used to calculate the network yield stress. To determine whether the rate of rotor acceleration affected the measured yield stress, a series of tests were made with a 1.6% Cm semi-bleached kraft pulp (SBK-4) varying rotor acceleration from 2.9 x 1 0 - 5 to 1.9 x 1 0 - 1 rad/s 2 . An /-test was performed on the data to determine if any test mean differed significantly from the others. For this test set the critical region at the 95% confidence level was /o.os(4,45) = 2.60. The /-test gave 2.36, and therefore the means from the different tests were not significantly different. A similar series of tests were made using a 5% Cm 3.3 mm Spectra fibre suspension. For the man-made fibre suspension the critical region at the 95% confidence level was /o.os(2,38) = 3.17 and the /-test gave 0.463. Again the test means were not CHAPTER 2. STRENGTH OF FIBRE NETWORKS 55 A n g u l a r V e l o c i t y , r a d / s 0.0 0.1 0.2 0.3 0.4 0.0 1.0 2.0 3.0 4.0 R o t a t i o n a l S p e e d , r p m Figure 2.3: Torque vs. rotational speed for a 0.8% C m semi-bleached kraft pulp. The test was conducted with the Haake RV12 using rotor C P J B 1 and housing RVH1. Ac-celeration was 3.49 x 1 0 - 3 rad/s 2 . The suspension yielded at the point on the curve indicated by the arrow. CHAPTER 2. STRENGTH OF FIBRE NETWORKS 56 CO o oo i 111111 T A 1 1 T -A" T 1 TT • = S B K - 4 , 1.6% C m A = Spectra 900, 3.3 m m , 5.0% C 1 1 1 J U L J I I II I III I I I I I I I 10 .-5 , - 4 , - 3 10 ' 10 10 A n g u l a r Accelerat ion, r a d / s 2 10 Figure 2.4: Measured yield stress vs. rotor acceleration rate. A l l measurements were made with the Haake RV12 viscometer. Tests with SBK-4 used rotor MVIP , while those with 3.3 mm Spectra used rotor K L P 4 . Over the range measured the rate of rotor acceleration does not affect the measured yield stress. significantly different. Therefore rotor acceleration rate (within the range tested) did not affect the measured yield stress. The data for these tests are plotted against acceleration rate in Figure 2.4. For suspensions where ry > 1225 Pa , the pulp fluidizer was used to measure sus-pension yield stress. Maximum torque occurred just before the rotor began to move continuously as shown in Figure 2.5 for a 10.6% semi-bleached kraft pulp. Here the control voltage, the analogue signal at the motor speed controller, represents the time elapsed in the test since voltage was increased at 0.01 volt/s. The point indicated by the arrow in the figure is the maximum torque reached in the test. It has been interpreted as the point at which the network yielded. A summary of the test conditions and results (including the mean yield stress and CHAPTER 2. STRENGTH OF FIBRE NETWORKS 57 © 0.00 0.02 0.04 0.06 C o n t r o l V o l t a g e , V o l t s Figure 2.5: Yield stress determination for a 10.6% Cm semi-bleached kraft pulp. The test was conducted with the pulp fluidizer using rotor PF1 and housing P F H 1 . Ro-tor acceleration was 0.52 rad/s 2 . Continuous rotor movement occurred at the point indicated by the arrow. CHAPTER 2. STRENGTH OF FIBRE NETWORKS r 58 the distribution of the test results) is given in Tables E . l through E . l l . The raw data for all tests are listed in Table E.14. 2.4.1.2 D i s t r i bu t i on o f M e a s u r e d Y i e l d Stresses For any given test condition (fibre type and mass concentration) a wide range of yield stresses were measured in successive yield determinations. The wide range of individual test measurements is most likely due to inhomogeneities in the fibre network and has been noted by other investigators [Horie and Pinder, 1979; Garner, 1986]. In order to obtain a reasonable average measurement of the yield stress, approximately ten individual measurements were made for each test condition. The distribution of test measurements about the mean was found to be adequately described by a Gaussian distribution. In order to obtain a suitably sized data set, distribution analysis was made on the relative yield stress, Ty. This was calculated by first computing the mean for each test condition ^V = ^ E ^ (2-9) ni=i and then evaluating the relative displacement from the mean for each individual mea-surement in a test series Ty,i = {ryii-r;)lr-y (2.10) Thus, data for different test conditions could be combined irrespective of the absolute values of the individual measurements. Distribution analysis was made using * F R E Q , a computer program available on the U B C mainframe computer [Kita, 1975]. The frequency distribution of the relative test measurements for all tests is given in Figure 2.6. The standard deviation was 0.36, which means that on average the stan-dard deviation was 36% of the absolute mean value for any given test. It is interesting to compare the distribution of Ty for pulp fibres with that of man-made fibres. Fig-ures 2.7 and 2.8 give these frequency distributions respectively. The pulp fibres had CHAPTER 2. STRENGTH OF FIBRE NETWORKS 59 -1 . 5 -1.0 - 0 . 5 0.0 0.5 R e l a t i v e Y i e l d S t r e s s 1.0 Figure 2.6: Distribution of relative yield stress measurements for all tests. -1.0 - 0 . 5 0.0 0.5 R e l a t i v e Y i e l d S t r e s s 1.5 Figure 2.7: Distribution of relative yield stress measurements for all pulp tests. CHAPTER 2. STRENGTH OF FIBRE NETWORKS 60 d CO d~ C o CO d R e l a t i v e Y i e l d S t r e s s Figure 2.8: Distribution of relative yield stress measurements for all man-made fibre suspension tests. the narrower distribution (s=0.20) compared with the man-made fibres (s=0.45). One possible explanation of this is that the pulp fibres formed more uniform suspensions due to their greater fibre flexibility and wider fibre size distribution. 2.4.1.3 S u s p e n s i o n B e h a v i o u r a f t e r Y i e l d i n g After yielding, suspension flow behaviour depended on the fibre type and suspension concentration. The behaviour observed for a stone groundwood pulp (SGW-1) is i l -lustrated using the torque vs. rotational speed curves given in Figures 2.9 to 2.11. 1.5% Cm Stone Groundwood. After the yield stress was reached, the torque levelled off and remained nearly constant as the shear rate was increased. Individual floes could be seen moving in the annular gap (gap width was 20 mm) and suspension motion extended to the housing wall. CHAPTER 2. STRENGTH OF FIBRE NETWORKS 61 A n g u l a r V e l o c i t y , r a d / s 0.0 0.1 0.2 0.3 0.4 5 i ' 1 L_ 0.0 1.0 2.0 3.0 4.0 R o t a t i o n a l S p e e d , r p m Figure 2.9: Relative torque vs. rotational speed for a 1.5% Cm stone groundwood pulp. Haake RV12 with rotor C P J B 1 and housing RVH1. CHAPTER 2. STRENGTH OF FIBRE NETWORKS 62 Figure 2.10: Relative torque vs. rotational speed for a 3.0% Cm stone groundwood pulp. Haake RV12 with rotor M V I P and housing RVH1. CHAPTER 2. STRENGTH OF FIBRE NETWORKS 63 Figure 2.11: Relative torque vs. rotational speed for an 8.0% Cm stone groundwood pulp. Haake RV12 with rotor K L P 1 and housing RVH1. CHAPTER 2. STRENGTH OF FIBRE NETWORKS 64 3.0% Cm Stone Groundwood. After the suspension yielded the torque began to fall and a clear water annulus formed around the rotor. Floes were observed rolling within the annulus. As the shear rate increased further, the clear water annulus decreased in size as fibres were drawn into the annular region. At this point, fibre motion could be observed in a zone extending approximately 20 mm from the rotor surface. Pulp in the remaining 40 mm of the annulus remained as a plug, although cracks or fissures appeared on the suspension surface. As the shear rate increased, the torque began to increase and the zone of rotor influence grew. At the maximum shear rate achieved in the test, the zone of fibre motion extended 30-35 mm from the rotor surface but had not reached the housing wall (gap width was 60 mm). 8.0% Cm Stone Groundwood. After the suspension yielded, an annular region formed between the rotor and the bulk of the suspension. Rolling cylindrical floes moved in this zone which grew during the test. Some floes were forced out of the sus-pension during shearing. The zone of suspension motion remained in the vicinity of the rotor which was largely cleared of fibres with the exception of these rolling floes. Torque fell throughout the test and showed signs of levelling off at high shear rates. Despite the wide range of behaviour exhibited after motion, was initiated in the sus-pension, all tests showed a consistent maximum in shear stress development (a yield stress) prior to bulk movement within the suspension. 2.4.2 P u l p F i b r e N e t w o r k S t r e n g t h The average value of the yield shear stress, f^ , found for each of the pulp suspensions tested (semi-bleached kraft (SBK-1), stone groundwood (SGW-1) and thermomechan-ical pulp (TMP-1)) , is plotted in Figure 2.12. The straight lines drawn through the CHAPTER 2. STRENGTH OF FIBRE NETWORKS 65 Figure 2.12: Yield stress vs. mass concentration for pulp fibre suspensions. CHAPTER 2. STRENGTH OF FIBRE NETWORKS 66 data points are the result of linear regression fits to ry = aCmb using the computer program * F R P available at U B C [Le, 1983; Le and Tenisci, 1978]. The correlations are given below: S B K : Ty = 9 . 9 0 C m2 3 1 r 2 = 0.918 (2.11) S G W : Ty = 1 . 1 8 C m2 " r 2 = 0.963 (2.12) T M P : Tv = 1.39C7m 3 5 6 r2 = 0.992 (2.13) The exponent b varied with pulp type and was in the range reported by previous investigators [Kerekes et al., 1985]. At higher consistencies the data points began to deviate from the straight regres-sion lines drawn. For semi-bleached kraft, for example, the data points at 33% Cm fall significantly below the fitted regression line. The falling off of network strength at consistencies above C m ~ 8% was attributed to the increased quantity of air in the suspension. If the data obtained at higher mass concentrations (Cm > 8%) were eliminated from the regression fit, the following correlation was obtained S B K : ry = 8.36<7m2-79 r 2 = 0.965 (2.14) Note that the exponent b increased and the fit improved. However, all data are useful, and by correlating r „ with the volumetric fibre concentration 3, C„, an even better fit was obtained using all data S B K : ry = 1 .40C V 2 7 2 r 2 = 0.976 (2.15) It is Cv and not Cm that is important when describing the suspension yield stress. This fact is illustrated by the yield stress measured for a 33.6% Cm semi-bleached kraft pulp and that for a 30.8% Cm stone groundwood pulp. The data are given in Tables E.12 3The volumetric concentration of a fibre suspension is the volume of fibre divided by the total volume of the suspension. It can be estimated using the mass concentration, water retention value and bulk density of the suspension as discussed in Appendix C.4. CHAPTER 2. STRENGTH OF FIBRE NETWORKS 67 and E.13. In both cases, the yield stress increased significantly with increasing volume concentration (decreasing air content), although the mass concentration remained the same. The data are plotted against Cv in Figure 2.13. For the semi-bleached kraft at 33.6% Cm ry = 0.180C,,3 0 6 r2 = 0.986 (2.16) Indeed, most of the variation in yield stress observed between the pulp types shown in Figure 2.12 can be accounted for by the volume concentration. For all pulp data ry = 0 .577a 3 ' 0 1 r2 = 0.958 (2.17) The results of linear regression fits for all pulps are listed in Table E.15. 2.4.3 M a n - M a d e F i b r e N e t w o r k S t r e n g t h The fibre length distribution of man-made fibre networks are usually narrower than those of pulp fibre suspensions (compare for example Figures C . l and C.9). In addition, man-made fibre properties are more uniform and the fibres are not fibrillated. In the work described here the suspensions were prepared so that the fibres were neutrally buoyant. This prevented fibre sedimentation at low fibre concentrations. 2.4.3.1 N y l o n F i b r e s Suspensions of 1.92, 3.48, 5.35 and 7.13 mm long nylon fibres were prepared and tested. The network yield stress was determined in the same manner described previously for pulp fibre suspensions and the results plotted in Figure 2.14. Again straight lines were obtained by linear regression fits to the data. The yield stress was found to vary as the mass concentration raised to powers between 1.99 and 3.23. These results cannot be directly compared with those of Horie and Pinder [1979], even though they were conducted on identical fibres. This is due to the ionic nature of the Horie and Pinder suspensions which increased the suspension yield stress. In CHAPTER 2. STRENGTH OF FIBRE NETWORKS 68 Figure 2.13: Yield stress vs. volume concentration for a 33.6% Cm semi-bleached kraft (SBK) and a 30.8% Cm stone groundwood pulp (SGW). CHAPTER 2. STRENGTH OF FIBRE NETWORKS Figure 2.14: Yield stress vs. mass concentration for nylon fibre suspensions. CHAPTER 2. STRENGTH OF FIBRE NETWORKS 70 addition, Ganani and Powell [1985] attributed the increase in suspension yield stress to differences in suspending medium viscosity. Other work also indicated that suspending medium viscosity affected suspension yield stress. Steenberg et al. [1966] measured the shear modulus of Perlon fibres dispersed in sugar solutions of different viscosities and found that the shear modulus was reasonably constant until the suspending medium viscosity reached a value approximately ten times that of water. After this point a further increase in suspending medium viscosity reduced the network modulus sub-stantially. To confirm that the 33% wt/wt sucrose/water solution (/u = 3.9 mPa-s) used to prepare the nylon fibre suspensions did not affect the suspension yield stress, a series of tests was conducted in which 5 mm long nylon fibre suspensions were pre-pared using both water (fj. — 1.0 mPa-s) and the 33% sucrose/water solution. The yield stresses for these tests are compared in Figure 2.15. No significant difference in network strength could be detected between them. 2.4.3.2 S p e c t r a 9 0 0 F i b r e s The yield stress measured for the Spectra 900 fibres is given in Figure 2.16. Values of the exponent b in ry = aCmb were determined by linear regression and found to be 3.01 and 3.43 for fibre lengths of 3.34 and 6.20 mm, respectively. 2.4.4 A n a l y s i s 2.4.4.1 C o m b i n e d E x p e r i m e n t a l F i n d i n g s Fibre network strength will depend upon suspension and fibre properties. These include the volumetric concentration of the suspension C„, and the average length /, diameter d and stiffness EI of the fibres. Fibre geometry was correlated in terms of the fibre aspect ratio A = l/d, while the modulus of elasticity E was used to represent the fibre material. Thus, the data obtained for ry were correlated in terms of the following CHAPTER 2. STRENGTH OF FIBRE NETWORKS 71 i i i i 1111 i i i i i 1111 i i i i i 111 10" io° id ltf M a s s C o n c e n t r a t i o n , C m ( % ) Figure 2.15: Yield stress vs. mass concentration for 5 mm nylon fibre suspensions in water and a 33% wt/wt sucrose/water solution. There is no difference in the measured yield stress. CHAPTER 2. STRENGTH OF FIBRE NETWORKS 72 Figure 2.16: Yield stress vs. mass concentration for Spectra 900 fibre suspensions. CHAPTER 2. STRENGTH OF FIBRE NETWORKS 73 variables: ry = f(Cv,E,A) (2.18) The data were fitted to an equation of the form TY = aCvbEcAd (2.19) using multiple linear regression techniques. This gave the following correlations A l l pulp data: Tv — 4 Qg(^3.10^-0.168^0.316 r2 = 0.981 (2.20) Nylon data: Tv = 1 . 1 3 x l O "7 C 2 - 7 3 ^ 3 - 3 8 r2 = 0.860 (2.21) Spectra data: Tv = 1.67 x l O - ^3 1 5 ^ 2 - 3 6 r2 = 0.939 (2.22) Nylon/Spectra: Tv = 2.27 x i o - 8 C 2 - 8 9 £ ° - 1 5 7 A 2 - 9 5 r2 = 0.899 (2.23) A l l data: Tv = 5 . 6 7 x l O -2 C 2 - 8 3 A 0 6 6 0 r2 = 0.933 (2.24) where ry is given in Pascals and Cv is in percent. In all cases the exponent on Cv was approximately three. However, there was considerable uncertainty regarding the indices on both E and A. In the case of pulp fibres, suspension strength was described almost equally well by the volumetric concentration alone (Equation 2.17). The addition of E and A, which have been shown to be important in past experimental and theoretical work [Thalen and Wahren, 1964b; Bergman and Takamura, 1965; Horie and Pinder, 1979; Kitano and Kataoka, 1981a] did not improve the correlation substantially. Indeed, the correlated dependence of A was much lower than expected while the correlated dependence of E was opposite to that expected. 2.4.4.2 T h e o r y o f N e t w o r k F a i l u r e a t a C y l i n d r i c a l S u r f a c e Fibre networks are three-dimensional structures that possess mechanical strength and thus solid-like properties. The network strength arises from cohesive forces that act at CHAPTER 2. STRENGTH OF FIBRE NETWORKS 74 1 1 F max F 2 F 2 Figure 2.17: Forces due to fibre bending. fibre contact points to oppose relative movement between adjacent fibres. Although many individual forces may act to impart strength to the fibre network, the dominant force usually arises from elastic fibre bending that induces frictional resistance at fibre contact points. This force is due to normal forces, is termed "type-C" by Kerekes et al. [1985], and is illustrated in Figure 2.17. If one assumes that this force is primarily responsible for the strength of a fibre network, then one would expect that the total network strength would depend on those factors affecting the magnitude of this force: the fibre concentration, the aspect ratio and stiffness of the fibres, and the coefficient of friction between the fibres. An analysis relating these factors to the yield stress, r y, follows. The volumetric fibre concentration, C„, and the fibre aspect ratio, A, determine the number of fibre/fibre contacts, n c , in a suspension. Wahren [1980] gives the following equation relating Cv to A and n c For algebraic purposes it is useful to obtain a simplified form of this equation. When cv = 8irA (2.25) CHAPTER 2. STRENGTH OF FIBRE NETWORKS 75 nc >^ 1 and A >^ n c , equation 2.25 may be simplified to C = (2.26) and thus the number of contacts per fibre is given by n. = ^ (2.27) The force per fibre contact can be estimated using simple beam bending theory. The maximum deflection, 6max, of a simple beam supported at two points is F l 3 Smax = — - (2.28) where F is the force on the fibre, 1 is the fibre segment length, E the modulus of elasticity and I the area moment of inertia, 7rr 4/4 for a solid rod where r is the rod radius. As the deflection is small, 8 ~ sinfl = l / r c = 8 m a x / l , where r c is the radius of fibre curvature. Thus 8max = l 2 / r c . Substituting this into Equation 2.28 gives r-'-g. (2.29) The segment length depends on the number of fibre contacts, 1 = l/nc. The force per fibre contact is given by Equation 2.29. Thus = ( 2 - 3 0 ) The friction force per contact is proportional to the normal force, Fcj — npFcn. It is also necessary to estimate the radius of curvature of the fibre segments in the suspen-sion. Wahren [1980] assumed that the effective average radius of curvature equalled the fibre length. However, it could be argued that locally the radius of curvature ap-proaches a fibre diameter. In any case, if we assume that the radius of curvature is equal to a constant times the fibre length, rc = kl, then Equation 2.30 can be simplified to CHAPTER 2. STRENGTH OF FIBRE NETWORKS 76 We must now calculate the number of fibres per square metre of shearing surface affected in a test. At a minimum, all the fibres one fibre length from the shearing surface (the inner cylinder) will be affected, i.e. _ Cv-K((R + iy-R*)L  f ' m i n - wrH(2nRL) { Z ' 6 Z ) When R^> I then Equation 2.32 becomes rc/.rmn = ~ T (2.33) 7T7* However, due to the continuous nature of the contact between all fibres in a suspension, the shear stress will be transmitted to fibres further than one fibre length from the shearing surface. Thus the total number of fibres affected will be proportional to nf = k"nfiJnin, where k" is an interaction parameter. While the exact nature of k" is unknown, it is likely proportional to the number of fibres in the the volume swept out by a single fibre [Kerekes et al., 1985]. Thus k" cx \CVA2 (2.34) By combining equation 2.33 with equation 2.34 we obtain: " R£) (2-35) Therefore the total shear stress sustainable by the network will be given by the total number of fibres affected (equation 2.35) times the force per fibre which is obtained by multiplying the frictional force per fibre contact (equation 2.30) by the number of contacts per fibre (equation 2.27). This gives: TY = aClEA2 (2.36) where a contains all the proportionalities and constants. Equation 2.36 was developed for a suspension of uniform fibres where network forces arise from elastically bent fibres and where n c >• 1 and A >^ n c . The fibre suspensions CHAPTER 2. STRENGTH OF FIBRE NETWORKS 77 tested here did not strictly meet these requirements, and some difference between theory and experiment was expected. Plotting solutions to Equation 2.25 showed that when 100 < A < 25, n c cx C v 0 6 2 t o °- 7 6, and when Cv ~ 0.1 and 100 < A < 25, n c oc A1-2. This would effectively increase the dependence of ry on both Cv and A. For example, for A ~ 50 and Cv ~ 0.10, r y = C*AEA2A. Secondly, the pulp fibre length distribution was not uniform as is evident from the histograms presented in Appendix C. The effect that this would have on ry is not known. Finally, the pulp fibres were fibrillated as shown in Figure 2.18. The pulp fibres were flat and ribbon like, having many kinks, curls and frayed parts. At least part of the network force would be expected to arise from inter-fibre friction due to hooking with adjacent fibres—Kerekes et al. [1985] "type-B" forces. Our experimental findings (Equations 2.20 to 2.24) did show a strong dependence of ry on Cv with exponents calculated between 2.83 and 3.15. However, the indices on E and A predicted by theory were not supported and indeed are very different for pulp and man-made fibres. For the pulp fibres, the dependence on A is small, while that of E is opposite to that predicted. As "type-B" forces were expected to play a large part in determining pulp fibre network strength, a more flexible fibre would be expected to increase network strength by conforming to the available surface and thus exposing a maximum of fibre surface area to contact with other fibres. For the nylon and Spectra fibres shown in Figure 2.19, the fibres are rod-like beams and are not fibrillated. Here network strength was more likely to arise from bending forces alone. The correlation (Equation 2.23) did show some dependence on E and a strong dependence on A. The low dependence on E was likely due to the large variation in TY among the experimental data. When we eliminated some of this variability by correlating only the data for the 3 mm nylon and spectra suspensions, the dependence on E increased: TY = 2.04 x l O - 5 ^ 3 - 5 2 ^ 0 - 4 0 0 r 2 = 0.860 (2.37) 0.5 mm Figure 2.18: Photographs of (a) semi-bleached kraft (SBK-1) , (b) stone groundwood (SGW-1) and (c) thermomechanical (TMP-1) pulp fibres. CHAPTER 2. STRENGTH OF FIBRE NETWORKS 79 CHAPTER 2. STRENGTH OF FIBRE NETWORKS 80 A comparison between the measured and predicted yield stress using Equation 2.24 is made in Figure 2.20. The results of all regression fits to the data are included in Table E.16. 2.4.4.3 C o m p a r i s o n w i t h O t h e r W o r k The work of Garner [1986] can be fitted to a relationship like that of Equation 2.19, and yields or = 3.30x l O - 1 0 ^ 2 - 7 3 ^ 0 - 3 5 ^ 5 0 4 r 2 = 0.627 (2.38) where &T is i n Pascals and Cv is in percent. This equation shows the expected depen-dence on C v , a small dependence on the modulus of elasticity and a large dependence on the fibre aspect ratio. The equation developed by Soszynski [1987] (Equation 2.6) to predict the tensile breaking stress of fibre floes was simplified by first combining all the constants together to give d2 <rT = k'E — <7vnc4 (2.39) where 7 m a a : / / is the deflection per unit fibre length and is included in the constant, k'. If we substitute a suitable expression relating the number of fibre contacts to fibre suspension properties, further simplification may be made. Substituting Wahren's [1980] expression for the number of fibre contacts in a suspension (Equation 2.27), we obtain <rT = k" C„3EA2 (2.40) which is identical to the relationship found in Equation 2.36. A fit to Soszynski's [1987] data using <TT — aCbAd was unsuccessful, yielding r 2 < 0.4. The scatter in the data combined with the limited range over which the variables changed likely accounted for the poor correlation. CHAPTER 2. STRENGTH OF FIBRE NETWORKS o = SBK, Water • = SGW, Water o = TMP, Water A = 2 m m N y l o n , 33% S u c r o s e / W a t e r ffi = 3 m m N y l o n , 33% S u c r o s e / W a t e r B = 5 m m N y l o n , 33% S u c r o s e / W a t e r v = 7 m m N y l o n , 33% S u c r o s e / W a t e r • = 5 m m N y l o n , Water H = 3.3 m m S p e c t r a 900, 1 9 % E t h a n o l / W a t e r o = 6.2 m m S p e c t r a 900, 1 9 % E t h a n o l / W a t e r • cy o B B a B a • < " i i i i i IIIIII i i i II i n u n 1 1 ""' 10" 10° id lcf i o 3 i o 4 P r e d i c t e d Y i e l d S t r e s s , Pa. 10° 10" Figure 2.20: Measured yield stress for all data is plotted against the value from Equation 2.24. CHAPTER 2. STRENGTH OF FIBRE NETWORKS 82 2.5 Conc lus ions 1. When subjected to increasing shear in a concentric cylinder tester, a fibre suspen-sion exhibited a maximum sustainable torque which is a measure of its network strength. The shear stress corresponding to this torque has been called the net-work yield stress, r y. 2. For any given fibre suspension, the network yield stress was correlated by an expression of the form Ty = aCmb where Ty was the suspension yield stress in Pascals, C m was the mass concentration in percent, and a and 6 were constants which depended on fibre type. Correla-tions that used the mass concentration were found to describe suspensions when the presence of a gas phase was minimal, that is, where C m < 8%. Above ap-proximately 20% Cm, equations correlated in this manner deviated significantly from the experimental data due to the presence of gas in the suspension. 3. Over a wide range of consistency, network yield stress was correlated with the volumetric concentration of the suspension, C„, as Ty = aCb This equation was found to be valid for volume concentrations up to 41% and accounted for the presence of gas in the suspension. The constants a and b depended on fibre type. Experimental results showed that b ~ 3.0. 4. Differences in network yield stress between fibre types were accounted for when the fibre properties of aspect ratio and elastic modulus were included in correla-tions of the form Ty = aCvbEcAd CHAPTER 2. STRENGTH OF FIBRE NETWORKS 83 Our results showed that the exponents of E and A were quite different for the pulp and man-made fibre suspensions. This may be due to the wide range of properties that exist in any given pulp sample and the tendency for fibrillation to occur only for pulp fibres. For all fibres (pulp and man-made) tested Ty = 5.67 x 10- 2 C V 2 - 8 3 A°- 6 6 0 r 2 = 0.933 Note that the fibre modulus of elasticity did not enter into this correlation. 5. Where fibre network strength is due solely to friction produced by normal forces among interlocking fibres, and where nc >^ 1 and A >^ rac, a theoretical analysis suggested that the yield stress varied as Ty = aCv3EA2 Our experimental findings showed distinct differences between pulp and man-made fibre suspensions. The pulp fibres tested showed that r y varied approxi-mately as C„ 3. However, they did not show a dependence on E and only a marginal dependence on A. This may be due to the strong contribution of "type-B" forces to the network strength, the wide fibre length distribution, or the variation of E between individual fibres. The man-made fibre suspensions also showed that r y varied as C„ 3. The yield stress varied as A raised to powers between 2.5 and 3.5, a larger dependence than anticipated. A dependence of r v on E was only apparent when a selected data subset was analysed, but it did not approach the predicted linear relationship. As previous investigations have found a linear dependence of Ty on E, our inability to duplicate this result suggests a shortcoming in the analysis. 6. Our experimental results covered approximately two decades in mass concentra-tion (0.4-33.6% C m ) and thereby fill a void in the literature on pulp fibre network strength, as shown in Figure 2.21. CHAPTER 2. STRENGTH OF FIBRE NETWORKS 84 P-. o Xi f-< © -t-> GO o a) •«—t 2 o 10" T e n s i l e M e t h o d s Jiuasij^Sta^t_ic_Methgds_ D y n a m i c M e t h o d s A Wet Web S t r e n g t h o S t r e n g t h o f F i b r e F l o e s • T h i s Work, S B K - 1 0 C I i i 1111 10° lOf M a s s C o n c e n t r a t i o n , C m (%) Figure 2.21: Yield stress vs. mass concentration for semi-bleached kraft pulp (SBK-1) compared with literature data. The data, points for SBK-1 below 10% C m were obtained with the Haake RV12, while the data points above 10% Cm were obtained with the pulp fluidizer. CHAPTER 2. STRENGTH OF FIBRE NETWORKS 85 2.6 R e c o m m e n d a t i o n s f o r F u t u r e W o r k 1. The effect of fibre length distribution on network yield strength should be deter-mined. This can be approached in two ways. Pulp suspensions of various length distributions can be produced by screening pulp samples, measuring the length distribution of the screened fractions, and measuring the yield stress of each frac-tion as a function of mass concentration. The various fractions could also be combined to generate a range of length distributions. In the case of man-made fibres, suspensions can be prepared by combining fibre length fractions in various proportions. 2. The dependence of pulp network strength on the fibre modulus of elasticity should be confirmed. In particular, our tests showed that the yield stress did not depend on fibre stiffness, while the work of Thalen and Wahren [1964a] and Bergman and Takamura [1965] showed that the yield stress was proportional to E. A method to easily and accurately determine the mean fibre elasticity and its distribution in a pulp sample would aid this work. C h a p t e r 3 D y n a m i c B e h a v i o u r o f P u l p S u s p e n s i o n s 3.1 I n t r o d u c t i o n The creation of motion in a pulp suspension is a necessary requirement for mixing. The ability to create fluid-like motion in medium consistency pulp suspensions has re-sulted in the rapid development of M C mixers and pumps, and their widespread use in industry. However, little research has been published on the rheology of medium consistency pulp suspensions under conditions of high shear. The following work is in-tended to provide a better understanding of the dynamic behaviour of low and medium consistency pulp suspensions. 3.2 L i t e r a t u r e R e v i e w 3.2.1 " F l u i d i z a t i o n " o f P u l p S u s p e n s i o n s In the last decade new developments in M C technology have been based on the pio-neering work of Gullichsen and Harkonen [1981] who concluded that There are no fundamental differences between low- (0-6%) and medium-(8-15%) consistency fiber suspensions with regard to their response to shear forces. The hydrodynamic properties of turbulent fiber suspensions resemble those of water. These statements were based on observations made in a concentric cylinder shear tester in which pulp suspensions were exposed to high levels of shear while the torque (shear 86 CHAPTER 3. DYNAMIC BEHAVIOUR OF PULP SUSPENSIONS 87 E 2 cn al D a cc o H 1 0 0 1000 2000 REVOLUTIONS, rpm Figure 3.1: Torque vs. rotational speed response of pulp in dynamic shear tests. Re-sults are for a bleached pine kraft tested by Gullichsen and Harkonen [1981]. Figure reproduced with the permission of T A P P I . stress) and rotational speed (shear rate) were measured. Their experimental findings are summarized in Figure 3.1. Here the rotational speed is plotted against torque for a bleached pine kraft pulp tested in the concentric cylinder device. These curves show a number of interesting features: 1. A yield stress must be exceeded before motion can be initiated in the suspension. This yield stress increased as the pulp consistency increased. 2. Once motion had been initiated, the shear stress increased or remained approxi-mately constant as rotational speed increased. 3. The pulp suspension flow curves exhibited a discontinuity as they neared the flow curve for water. The points on the curves in Figure 3.1 mark the instant at which CHAPTER 3. DYNAMIC BEHAVIOUR OF PULP SUSPENSIONS 88 the vessel contents were observed to come into a "vigorous state of turbulence". The onset of this turbulent state was found to be coincident with the observed discontinuity in the pulp suspension curves [Gullichsen and Harkonen, 1981]. 4. The torque vs. rotational speed curves for the pulp suspensions approximately followed the water curve after attaining this turbulent state. Gullichsen and Harkonen called the fluid-like state, in which a medium consistency pulp suspension behaved like water, "fluidization". New process equipment was quickly developed to exploit this finding. Machinery to pump and mix M C pulp suspensions employing centrifugal motion to provide "fluidization" are now in widespread use [Gul-lichsen, 1976; Gullichsen et al., 1981; Greenwood and Harkonen, 1986]. Screens that operate in the M C range, a unit operation previously thought to be possible only for low consistency suspensions, have been reported to be under development [Gullichsen et al., 1985]. In the pulp and paper literature the term "fluidization" has become synonymous with the creation of a fluid-like state in a pulp suspension. In particular, the term is used to imply creation of water-like motion in medium consistency pulp suspensions that are otherwise regarded as solid-like. However, in the chemical engineering literature, fluidization has another well-defined meaning, which is given by Grace [1982]: When gas or liquid passes upward through a bed of solid particles at a very low flow rate, a porous plate or grid is required to support part of the weight of the solids. The particles are stationary and form a packed bed. If the flow rate is increased, a point is reached where the solid particles are supported or very nearly supported by the drag exerted by the fluid. The particles are then mobile. This is said to be the point of minimum or incipient fluidization. In this thesis, the term "fluidization" will be used in a general sense to indicate creation of fluid-like behaviour. CHAPTER 3. DYNAMIC BEHAVIOUR OF PULP SUSPENSIONS 89 Gullichsen and Harkonen compared the disruptive shear stress determined at the point where the vessel contents became turbulent, to the disruptive shear stress for pulp suspensions measured by Duffy [1975]. These results, when plotted on logarithmic co-ordinates, yielded a straight line which gave good but "somewhat coincidental" agreement between the results. This led Gullichsen and Harkonen to speculate that " . . . the same basic mechanisms governing the response to shear forces at low consistency also apply to the medium-consistency range". Thus it would seem that by imposing sufficient shear to an M C pulp suspension, the fibre network can be totally disrupted, resulting in creation of a fluid-like state. However, maintaining this turbulent state requires a considerable power input, particularly at high pulp mass concentrations. The power dissipation per unit volume required to "fluidize" the bleached pine kraft calculated from the data of Gullichsen and Harkonen is given as a function of Cm in Table 1.2. 3.2.2 D i s r u p t i o n o f P u l p N e t w o r k s Wahren [1980] postulated that a fibre network could exhibit a "spectrum of states of dispersion and network formation". At one extreme, the network could be pictured as an infinitely large floe—the continuous three-dimensional fibre network envisioned in the mathematical model of Meyer and Wahren [1964] and discussed in Section 2.2.1. At the other extreme, the suspension was envisioned as a . . . fully dispersed, fluidized system, where fibres are free of mechanical en-tanglement (although in some cases interacting heavily with the suspending medium as an intermediary). Wahren also stated that In order to achieve fluidization of the network it is necessary to generate sufficiently intense and sufficiently small-scale fluid motions, which disperse the network on a sufficiently fine scale... CHAPTER 3. DYNAMIC BEHAVIOUR OF PULP SUSPENSIONS 90 and made an estimate of the power dissipation, e, required to achieve this fully dispersed state. The energy dissipation rate is related to the fluid stress and shear rate in both laminar and turbulent flow. Wahren used the relationship for laminar shear e = T T (3.1) and T = /IT (3.2) Thus, the energy dissipation rate can be expressed in terms of the shear stress within the fluid as e = r 2 / ^ (3.3) Wahren employed this laminar relationship to estimate the power dissipation required to "fluidize" pulp suspensions. He substituted the relationship for the distruptive shear stress of a pulp suspension found by Moller and Duffy [1978] rd = 3 . 4 C m 2 6 4 (3.4) for r and used the viscosity of water for fj. to obtain e = 1 . 1 6 x l 0 4 C m B 2 8 (3.5) where e is given in W / m 3 and Cm is in percent. Estimates for the power required to "fluidize" a pulp suspension given by Equation 3.5 are included in Table 1.2. There is a very large discrepancy (almost three orders of magnitude) between these estimated powers and those measured experimentally by Gullichsen and Harkonen [1981]. Yet both workers ascribe the onset of fluid-like behaviour to the same factor—the imposition of stresses in the pulp suspension sufficient to rupture the fibre network. The large difference in power required for "fluidization" may be explained by several factors. First, logic and Wahren's postulate suggest that in any flow there is likely to CHAPTER 3. DYNAMIC BEHAVIOUR OF PULP SUSPENSIONS 91 be a spectrum of "fluidized" states, from one initially having floes moving relative to one another through states where the size of the floes are progressively decreased, to a totally dispersed state in which individual fibres move relative to one another. Wahren's power estimate applies to the latter l imit. The "fluidized" state observed in Gullichsen and Harkonen's experiments was classified as one of "rigourous turbulence", but it may in fact be some intermediate case. A second factor that may explain the discrepancy is Wahren's use of the viscosity of water to characterize the pulp suspension in a fluid-like state. If a pulp suspension is "fluidized", it may be assigned an apparent or effective viscosity. It is well known (e.g. see Rutgers [1962, 1963] or Krieger [1967]) that suspensions of solid particles have effective viscosities greater than that of the base fluid, with the viscosity increas-ing monotically with concentration. For a medium consistency pulp suspensions the apparent viscosity is certainly greater than that of water. Finally, the use of a disruptive shear stress based on low consistency data to estimate suspension strength in the medium and high consistency range leads to overestimation of the network strength. As shown in Chapter 2, the increased presence of a gas phase dramatically lowers network yield stress, particularly for suspensions above 20% Cm- For example, at 30% Cm the network strength estimated by extrapolation of low consistency correlations can be an order of magnitude too high. Since a "fluidized" pulp suspension can be assigned an apparent viscosity, it is appropriate to examine how the presence of fibrous particles affects the viscosity of Newtonian fluids. 3.2.3 V i s c o s i t y o f F i b r o u s S u s p e n s i o n s The literature dealing with the viscosity of semi-concentrated and concentrated sus-pensions of rod-like particles in Newtonian and non-Newtonian fluids has recently been reviewed by Ganani and Powell [1985]. They divided the studies into three regimes: CHAPTER 3. DYNAMIC BEHAVIOUR OF PULP SUSPENSIONS 92 dilute, semi-concentrated and concentrated. The criterion A~2 < Cv < A"1 is used to define the semi-concentrated regime, where A is the aspect ratio of the fibres. For a semi-bleached kraft pulp suspension the semi-concentrated regime would correspond to suspensions having mass concentrations between approximately 0.05 and 1.6% Cm. The reviewed studies showed shear thinning behaviour in this regime, while Newtonian behaviour was approached at sufficiently high shear rates. For example, at low aspect ratios (A 10) fibrous suspensions were found to approach Newtonian behaviour for shear rates greater than > 0 .1s - 1 . As the aspect ratio increased, the onset of Newtonian behaviour occurred at higher shear rates while increasingly non-Newtonian behaviour was observed at lower shear rates. The concentrated regime is given by Cv > A-1. Pulp suspensions with C m greater than approximately 1.6% fall into this category. Here suspension viscosity falls as the shear rate increases, although it remains above the viscosity of the suspending medium even at high shear rates. Ganani and Powell concluded that the relative viscosity of suspensions in Newto-nian fluids depends upon the volume concentration, the aspect ratio and flexibility of the suspension particles, and the shear rate. A number of equations are given in the literature to correlate the relative viscosity, fiT, (the ratio of the viscosity of the sus-pension, figp, to that of the suspending medium alone, fi) for suspensions of rod-like particles in Newtonian suspending media. Brodnyan [1959] developed the following equation for rod-like particles where k is a crowding factor equal to 1 / C „ , m a x and expected to be equal to 1.91 for fibres with ellipsoidal cross sections. Brodnyan tested this equation with limited experimental data up to approximately Cv = 1.0%, and found good agreement up to Cv = 0.5%. (3.6) CHAPTER 3. DYNAMIC BEHAVIOUR OF PULP SUSPENSIONS 93 Hashin [1969] gave Ur = 1 + 2CV (3.7) 1 - C „ for rigid cylinders oriented in the direction of shear flow. Nicodemo and Nicolais [1974a, 1974b] correlated the relative viscosity of glass fibre Fedors [1974, 1975] showed that an equation developed for the Newtonian viscosity of particles or aggregates can be applied to fibre suspensions. Equation 3.9 was found to be valid up to 7% C„ for glass fibres in aqueous solutions of polyethylene oxide. Most theoretical equations assume that the fibres act independently. As pulp suspensions are flocculated, some difference between the theoretical predictions and experimental data are expected. Note that Equation 3.9 has the term (CViTnax—Cv) in the denominator, so that as Cv —* Cv<max, fir —* oo. The term (1 — kCv) in Equation 3.6 produces the same effect when Cv —> 1/fc. In order to use Equations 3.6 and 3.9 to estimate suspension viscosity, an accurate value of the maximum volume concentration must be measured. Fedors [1974] measured Cv<max for randomly packed high aspect ratio rods and found Cv<max = 0.29. However, in pulp suspensions Cv can approach 0.41 (see Table E.14). The dependence of relative viscosity on particle volumetric concentration predicted by the above equations is shown in Figure 3.2 for a fibre having an aspect ratio of 80 assuming a maximum volumetric concentration of 0.41. The differences in viscosity predicted by these equations are large, and in the absence of experimental data it is not possible to determine which equation, if any, would be best. In addition, suspension viscosities depend on the shear rate which is not explicitly included in these equations. (3.9) CHAPTER 3. DYNAMIC BEHAVIOUR OF PULP SUSPENSIONS 94 V o l u m e F r a c t i o n , C v Figure 3.2: Relative viscosity predicted by equations in the literature: Brodnyan [1959] (A = 80, k = 1.91), Hashin [1969], Nicodemo and Nicolais [1974a, 1974b], Fedors [1974, 1975] (Cv>max = 0.41), and Ziegel [1970] ( r oo, Z = 0.75, A = 80). Experimental data: O = Nawab and Mason [1958], x = Steenberg and Johansson [1958], • = Ziegel [1970], • = Corey [1972], V = Nicodemo and Nicolais [1974b], o = Maschmeyer and Hil l [1977], A = Kitano and Kataoka [1981a]. Details are given in Table D.6. CHAPTER 3. DYNAMIC BEHAVIOUR OF PULP SUSPENSIONS 95 One expression, developed by Ziegel [1970], contains a dependency of shear rate on relative viscosity the equilibrium between free particles and agglomerates, Z the degree of agglomeration, Kitano and Katoka [1981a] to study fibrous suspensions. Note that as T —> oo, 1/T —> 0 and nr approaches a limiting value that depends upon the degree of agglomeration, fibre aspect ratio, and volume concentration. The experimental work of Ziegel for glass fibres (A — 500) in various Newtonian polymer fluids gave relative viscosities between 4.6 and 34 as T —• oo. The results obtained by Kitano and Katoka, where vinylon fibres (A — 63-120) were suspended in Newtonian fluids, gave values of 1.31 to 2.47 as limiting relative viscosities. In these studies the suspension volumetric concentration was never greater than 6%. Solution to Equation 3.10 for T —• oo, Z — 0.75, and A — 80 is included in Figure 3.2. The above equations point out a number of factors that govern suspension viscosity: 1. The relative viscosity of a suspension decreases with increasing shear rate but is greater than the suspending medium viscosity even at high shear rates. 2. As the volumetric concentration of the suspension approaches a maximum vol-umetric concentration, the suspension viscosity becomes infinitely large. This corresponds to the loss of fluid-like nature of the suspension. 3. The relative viscosity is expected to depend on fibre properties, including the fibre aspect ratio and flexibility. However, while all the equations specify a dependence on the volumetric concentration, only Equations 3.6 and 3.10 give a dependence on A. The dependence on E has not been treated. (3.10) where //* is an interaction or closeness of approach parameter, (3 the rate constant for CHAPTER 3. DYNAMIC BEHAVIOUR OF PULP SUSPENSIONS 96 4. These correlations have been developed for two-phase suspensions. The presence of a gaseous phase will increase Cv wlrich is accounted for by the equations. However, the gas may also affect suspension rheology in other ways. 5. Present experimental data are available mainly at low volume concentrations and primarily for man-made fibres. As M C pulp suspensions have volumetric concentrations between approximately 0.16 and 0.41, extrapolation into this range cannot be made with confidence. An expererimental investigation of the shear stress versus shear rate behaviour of sulfite pulp suspensions was carried out by Steenberg and Johansson [1958]. From their data, pulp suspension viscosity could be measured, and values are included in Figure 3.2 for an apparent shear rate of 105 s _ 1 . Suspensions below 1.0% Cm were found to be Newtonian. However, as suspension concentration was increased, non-Newtonian behaviour was observed. 3.2.4 C h a r a c t e r i z a t i o n o f M i x e r s High levels of shear must be applied to fluidize pulp. These can be attained in concentric-cylinder devices similar to that used by Gullichsen and Harkonen [1981] and the pulp fluidizer used in this study. While these devices do not create a standard flow, i.e. pipe flow or flow in a smooth wall annulus, the flow is industrially important. For example, the Kamyr M C pump and mixer are very similar in size and geometry to the fluidizer and likely create similar flows. In essence, the pulp fluidizer is a baffled turbine mixer and can be characterized as a mixing device. The power required to rotate an impeller in a mixing vessel can be expressed as a function of fluid properties and vessel geometry [Bates et ai, 1966; Skelland, 1983]: P = f{D,DT,H,C,S,LB,WB,w,p,n,N,g,nun2) (3.11) where CHAPTER 3. DYNAMIC BEHAVIOUR OF PULP SUSPENSIONS 97 D and DT = impeller and vessel diameter H = liquid depth C — height of impeller above the vesssel floor S = impeller pitch LB and WB — length and width of impeller blade w = baffle width p and /x = fluid density and viscosity N == impeller rotational speed g = acceleration due to gravity n i = number of impeller blades or lugs n 2 = number of baffles Dimensional analysis allows Equation 3.11 to be rewritten as • f i m w ^ y (§)•(§)• where Np is called the Power number. For systems of constant geometry where surface waves and vortices are absent, the power number is only a function of the Reynolds number, i.e. NP = /[NJU] (3.13) At high Reynolds numbers, (NRS > 1,000), when the vessel is adequately baffled, the power number becomes independent of Reynolds number, so that P = NPMlhD*N3P (3.14) where iVp,turb is a constant that depends only on the impeller and vessel geometry. CHAPTER 3. DYNAMIC BEHAVIOUR OF PULP SUSPENSIONS 98 3.3 E x p e r i m e n t a l 3.3.1 Ob jec t i ve The objective of this experimental work was to better understand the behaviour of medium consistency pulp suspensions. In particular, the aim was to determine whether there are clearly defined regimes of suspension behaviour, and to investigate whether the fluid-like state reported by Gullichsen and Harkonen can be classified in terms of conventional fluid mechanics, for example, by an apparent viscosity. 3.3.2 Equ ipmen t The dynamic tests were conducted in a concentric cylinder device called the pulp flu-idizer. The fluidizer is powered by a 30 hp (22.4 kW) variable speed DC motor and permits rotors attached to the shaft to reach speeds of up to 5000 rpm (524 rad/s). The pulp suspensions are contained in a chamber formed between the rotor and a housing which provides the outer cylinder surface. The rotors had lugs that protruded into the pulp suspension to prevent suspension slippage at the rotor surface, while the housings were baffled to prevent fibre slippage at the outer wall. By using different rotors and housings, the gap width (distance between the tips of the rotor lugs and housing baffles) and chamber volume were varied. Two rotor/housing combinations were used for the majority of the work discussed here: a wide-gap configuration (rotor PF2 and housing PFH1) having a gap width of 50 mm, and a narrow-gap configuration (rotor PF2 and housing PFH2) having a gap width of 5 mm. Both configurations are illustrated in Figure 3.3. Two other rotors were used with the housings. Rotor PF1 has a diameter of 70 mm, while rotor PF4 has the standard diameter of 100 mm but deeper vanes. Detailed dimensions for the rotors and housings appear in Tables A . l and A.2. A clear Lexan plate formed the front face of the fluidizer chamber, permitting observation and photography of the suspensions as illustrated in the plan views in Figure 3.3. The CHAPTER 3. DYNAMIC BEHAVIOUR OF PULP SUSPENSIONS 99 Figure 3.3: Pulp fluidizer rotor and housing configurations used in dynamic tests. Dimensions are given in millimetres, (a) Wide-gap configuration (PF2 /PFH1) , (b) Narrow-gap configuration (PF2 /PFH2) . CHAPTER 3. DYNAMIC BEHAVIOUR OF PULP SUSPENSIONS 100 suspensions could also be viewed along the cylindrical axis through a 35 mm diameter Lexan port in the housing wall. Full details of the fluidizer are given in Appendix A. 3.3.3 F i b r e a n d S u s p e n s i o n P r o p e r t i e s Four different types of pulp fibres were studied in the dynamic experiments. Some pulps were identical to those used in the yield stress tests discussed in Chapter 2. Samples of unbleached softwood kraft (UBK-1) , stone groundwood (SGW-1) and ther-momechanical (TMP-1) pulp were obtained from MacMil lan Bloedel's Powell River mill; semi-bleached kraft (SBK-2 and 4) was provided by Canadian Forest Products' Howe Sound mil l . Data characterizing these pulp samples are given in Table 2.1. Fibre suspension properties were characterized as described in Appendix C. 3.3.4 P r o c e d u r e Prior to a test the pulp fluidizer was filled with pulp. Low consistency pulp suspensions (0-6% Cm) were added through the side addition port while higher consistency pulp suspensions were packed from the front of the chamber. For suspensions above 8% C m , the mass of the pulp packed into the fluidizer was measured and permitted calculation of the bulk density. The suspension gas content could then be estimated as described in section C.4. A standard procedure was adopted based on the results of experiments discussed in section 3.4.1. The fluidizer speed controller was increased linearly from rest to 5000 rpm in 10 seconds; the maximum speed was held for 5 seconds, followed by a linear deceleration to rest in a further 10 seconds (Figure 3.4). Data (shaft torque, rotational speed, and suspension temperature) were acquired for 30 seconds. Data measurements and speed adjustments were made at a frequency of 25 Hz. Details of the measurement sensors are given in Appendix A , and a listing of the program controlling the fluidizer and data acquisition appears in Table B . l . In the results reported here, the net torque CHAPTER 3. DYNAMIC BEHAVIOUR OF PULP SUSPENSIONS 101 o.o 10.0 20.0 30.0 T i m e , s Figure 3.4: Rotational speed vs. time for a 10% Cm semi-bleached kraft pulp in a standard test. Test PFD.094. was calculated by subtracting the frictional torque from the total torque. Only the acceleration portion of the tests are reported. When required, the test conditions could be varied, or the pulp fluidizer controlled manually. For example, manual operation was used when high speed films were made at fixed rotational speeds. The majority of the tests were video taped which permitted review of the exper-iments. As the effective framing rate of the video camera is approximately 30 fps (frames per second), high speed motion films were required to study the rapid fibre motion occurring in "fluidized" suspensions. A Hycam motion picture camera capable of 5000 pps (pictures per second) was chosen for this purpose. F i lm lengths of 30 m were used in the camera, and because the camera takes approximately 30 m of film to reach 5000 pps, the framing rate varied from 1000 to 5000 pps during a test. A 1/2.5 shutter was used, so that the effective shutter speed was 2.5 x the framing rate. The exact interval between frames was determined from timing marks generated on the film CHAPTER 3. DYNAMIC BEHAVIOUR OF PULP SUSPENSIONS 102 at 1000 Hz intervals during a test. Details of the film analysis procedure are given in Appendix G. A l l tests in which the computer was used to acquire data are identified by a sequen-tial record number, i.e. PFD.xxx. Test conditions are listed in Table F . l . 3.4 R e s u l t s a n d D i s c u s s i o n 3.4.1 P r e l i m i n a r y T e s t s a n d T e s t R e p r o d u c i b i l i t y Preliminary tests were conducted to establish a standardized set of conditions for study-ing pulp suspension dynamic behaviour. The significance of these findings are discussed below. A typical rotational speed vs. elapsed time curve for a standard test is given in Figure 3.4 for a 10% C m semi-bleached kraft pulp. Here the controller speed (the speed set by the computer) is compared with the actual rotor speed during the test. During most of the test, the actual rotor speed lagged the requested rotor speed by approxi-mately 0.3 seconds. However, at the end of the deceleration period, the measured speed departed considerably from that requested. This was likely due to a combination of two factors: the inertial forces of the fluidizer, and the slow response time of the rotational speed sensor when the shaft speed fell below 1000 rpm during deceleration. This must contribute to the hysteresis present in the torque vs. rotational speed curve shown in Figure 3.5. The amount of hysteresis decreased as the acceleration and deceleration rates were decreased. In addition, Figure 3.5 shows that a drop in torque occurred during the portion of the test where rotational speed was held constant for 5 seconds. This apparent thixotropic (shear thinning) behaviour was not observed for tests made with Newtonian fluids, and is attributed to a number of factors: 1. Changes in fibre properties resulting from stresses during the test period. The CHAPTER 3. DYNAMIC BEHAVIOUR OF PULP SUSPENSIONS 103 Angular Velocity, rad/s 0 100 200 300 400 500 J I I 1 I I Rotational Speed, rpm Figure 3.5: Hysteresis is evident in the torque vs. rotational speed curve of a 10% C, semi-bleached kraft (SBK-2). Test PFD.094. CHAPTER 3. DYNAMIC BEHAVIOUR OF PULP SUSPENSIONS 104 effect of mechanical treatment on fibre properties is discussed in detail in Ap-pendix H. The amount of fibre degradation increased with mechanical treatment. 2. A n increase in suspension temperature caused by energy dissipation. As the en-ergy expended creating flow is ultimately dissipated as heat, the temperature of the suspensions increased substantially. For example, in the thirty second dura-tion of a standard test, the temperature of a 10% semi-bleached kraft pulp in-creased approximately 6°C in the wide-gap configuration and approximately 28°C in the narrow-gap configuration. This temperature increase reduces suspending medium viscosity, which in turn also reduces suspension viscosity [Corey, 1972]. In addition, pulp fibres become more flexible with increasing temperature which may reduce suspension viscosity as well. 3. Gas separation which lowered the suspension density in the rotor vicinity. This is discussed in detail in section 3.4.2.7. To avoid changes in suspension behaviour due to heating and mechanical treatment, it was decided that the test period should be as short as possible. This required fairly rapid acceleration and deceleration rates, and resulted in hysteresis in the torque vs. rotational speed curves. Therefore only the acceleration portion of the curves were used in the analysis. A l l tests were begun from rest and ramped up and down at the same rate which allowed comparison between them. The torque measured at any rotational speed was the sum of the torque on the rotor due to fluid flow in the fluidizer chamber, and that caused by friction in the bearings and seals of the pulp fluidizer. The net torque reported here was obtained by subtracting the machine friction torque from that measured in a test. The machine friction was measured as a function of rotational speed by conducting a standard test with the fluidizer chamber empty (only air present). The result for one such test is given in Figure 3.6. As the accuracy of the torque sensor was ±0.3 N-m, the subtraction CHAPTER 3. DYNAMIC BEHAVIOUR OF PULP SUSPENSIONS 105 A n g u l a r V e l o c i t y , r a d / s o 0 100 200 300 400 500 • J I I I _J I o g o o I 1 1 I I I 0 1000 2000 3000 4000 5000 R o t a t i o n a l S p e e d , r p m Figure 3.6: Shaft torque due to friction forces in the pulp fluidizer. Wide-gap configu-ration. Test PFD.066. CHAPTER 3. DYNAMIC BEHAVIOUR OF PULP SUSPENSIONS 106 A n g u l a r V e l o c i t y , r a d / s 0 100 200 300 400 500 1 I ' 1 1 1 0 1000 2000 3000 4000 5000 R o t a t i o n a l S p e e d , r p m Figure 3.7: Test reproducibility: 10% Cm SBK-2 . Sequential tests: PFD.043, PFD.044 and PFD.045. A standard test with water (PFD.047) is given as a reference curve. The fluidizer chamber was repacked between tests. to remove the friction torque from a standard test increased the error to i 0 . 6 N-m. When large torques were measured the relative error was small. However, when the measured torque was low (which was common for measurements made at rotational speeds below 500 rpm) the relative error could be substantial. The reproducibility between tests is illustrated by the torque vs. rotational speed curves of successive tests made with a 10% and 16% C m semi-bleached kraft shown in Figures 3.7 and 3.8. Some variability was introduced, by experimental limitations achieving identical conditions between test runs. For example, obtaining identical mass CHAPTER 3. DYNAMIC BEHAVIOUR OF PULP SUSPENSIONS 107 A n g u l a r V e l o c i t y , r a d / s 0 100 200 300 400 500 J L_ - I I i . Water PFD.063 PFD.064 "PFD7665" 0 1000 2000 3000 4000 5000 R o t a t i o n a l S p e e d , r p m Figure 3.8: Test reproducibility: 16% Cm SBK-2 . Sequential tests: PFD.063, PFD.064 and PFD.065. A standard test with water (PFD.047) is given as a reference curve. The fluidizer chamber was repacked between tests. Test PFD.063 lies below the other tests due to the greater gas content of the suspension. CHAPTER 3. DYNAMIC BEHAVIOUR OF PULP SUSPENSIONS 108 Table 3.1: Comparison of chamber dimensions used in the Gullichsen and Harkonen tests with the wide-gap configuration configuration used in this study. Chamber Gullichsen &; This work Component Units Harkonen [1981] (PF2/PFH1) Housing diameter mm 213 220 depth mm 100 100 number of baffles 4 6 baffle dimensions mm 10x10 10x10 Rotor diameter mm 100 100 depth mm 100 100 number of lugs 3 6 lug dimensions mm 10x10 10x10 Gap width mm 46.5 50.0 Volume of chamber m 3 2.99 x I O - 3 3.18 x 10"3 concentration and suspension packing between tests was difficult. The heterogeneous three-phase nature of the pulp suspensions was believed to cause the rapid fluctuations in torque during rotor acceleration shown in Figures 3.7 and 3.8. The magnitude of the torque fluctuations increased as the mass concentration of the suspension increased. 3.4.2 W i d e - G a p E x p e r i m e n t s One aim of our research was to extend and explain the results obtained by Gullichsen and Harkonen [1981]. To accomplish this, a concentric cylinder chamber similar in dimensions to that used by Gullichsen and Harkonen was constructed (see Table 3.1). Note that with the exception of the number of rotor lugs and housing baffles, the chamber dimensions for the "wide-gap" configuration are almost identical to those used by Gullichsen and Harkonen. It was felt that increasing the number of lugs on the rotor would result in more effective momentum transfer to the suspension, while increasing the number of baffles would be more effective in preventing slip at the housing wall. CHAPTER 3. DYNAMIC BEHAVIOUR OF PULP SUSPENSIONS 109 A n g u l a r V e l o c i t y , r a d / s 0 100 200 300 400 500 1 I I I I l__ R o t a t i o n a l S p e e d , r p m Figure 3.9: Torque vs. rotational speed curves for SBK-2 in the wide-gap configu-ration. Tests for 0% (PFD.047), 2% (PFD.049), 4% (PFD.051), 6% (PFD.052) and 8% (PFD.054) Cm shown. The completion of the flow transition, as observed at the front face of the fluidizer, is indicated by a solid point on each pulp suspension curve. The error bars shown represent ± 1 standard deviation about the mean for multiple determinations. The data is given in Table F.2. 3.4.2.1 T o r q u e v s . R o t a t i o n a l S p e e d C u r v e s A semi-bleached kraft pulp (SBK-2) was used for a series of tests in the pulp fluidizer where suspension consistency was varied in steps from 0 to 16% Cm. The torque vs. rotational speed curves, corrected for machine friction, are shown in Figures 3.9 and 3.10 for these tests. Examination of the torque vs. rotational speed curves showed that: 1. As discussed in Chapter 2, a minimum stress, called the yield stress, must be CHAPTER 3. DYNAMIC BEHAVIOUR OF PULP SUSPENSIONS 110 A n g u l a r V e l o c i t y , r a d / s 0 100 200 300 400 500 0 1000 2000 3000 4000 5000 R o t a t i o n a l S p e e d , r p m Figure 3.10: Torque vs. rotational speed curves for SBK-2 in the wide-gap configuration. Tests for 0% (PFD.047), 10% (PFD.055), 12% (PFD.057), 14% (PFD.060) and 16% (PFD.063) C m shown. The completion of the flow transition occurred only for the 10% Cm suspension and is indicated by a solid point on the curve. CHAPTER 3. DYNAMIC BEHAVIOUR OF PULP SUSPENSIONS 111 A n g u l a r V e l o c i t y , r a d / s 0 100 200 300 400 500 I I I I 1 1— 0 1000 2000 3000 4000 5000 R o t a t i o n a l S p e e d , r p m Figure 3.11: Torque vs. rotational speed curves of 9.2-9.6% SBK-2 made at different rotor acceleration rates: Yield stress or continuous operation, 166 rpm/s (17.4 rad/s 2 ) , 250 rpm/s (26.2 rad/s 2 ) , 500 rpm/s (52.4 rad/s 2 ) . The dramatic drop in torque did not depend on the rate of acceleration. exceeded before continuous rotor motion occurs. 2. Once the rotor began continuous motion, the torque fell rapidly. For higher con-sistency pulp suspensions the magnitude of the drop was significant. A series of tests confirmed that the observed torque drop was not a function of the test condi-tions. Machine acceleration was varied from zero to that used in the standard test run (see section 3.3.4). The results, given in Figure 3.11, showed that the torque dropped dramatically after yield, regardless of the rate of rotor acceleration. CHAPTER 3. DYNAMIC BEHAVIOUR OF PULP SUSPENSIONS 112 3. The torque vs. rotational speed curves for the pulp suspensions displayed a range of behaviour. However, there were some similarities among all curves. In the lower rotational speed region the torque was higher than that of the water curve. As rotational speed increased, the torque for the pulp curves increased at a lower rate than that of the water curve and eventually crossed it. After a point the pulp curves began to parallel to the water curve although the torque could remain less than that for water. 4. In some cases, particularly with pulp suspensions having consistencies greater than 8 % C m , the torque reached a point where it remained nearly constant with increasing rotational speed. The torque therefore could become progressively less than the water curve. The flow observed during a test was classified into transitions and regimes which are discussed below and illustrated in Figure 3.12. 3.4.2.2 Y i e l d As described in Chapter 2, pulp suspensions exhibited a yield stress. The rotor turned approximately 10-25° before continuous rotor motion occurred. Due to the compression of the fibre network and the inability of the M C suspensions to flow before continuous rotor movement occurred, void regions appeared behind the rotor lugs as illustrated in Figure 3.12(a). 3.4.2.3 Tangen t ia l -Cav i t y R e g i m e After yielding, floes in the immediate rotor vicinity moved in a rolling, tumbling man-ner. As rotor speed increased, the fluid-like zone increased in volume as it expanded radially outwards from the rotor. The growth of this active zone formed a cavity which is clearly shown in Figure 3.13 in frames taken from a high speed motion picture film CHAPTER 3. DYNAMIC BEHAVIOUR OF PULP SUSPENSIONS 113 Figure 3.12: Regimes of semi-bleached kraft suspension behaviour in the wide-gap configuration as observed from the front face of the fluidizer: (a) Yielding: void spaces appear behind rotor lugs; (b) Tangential-Cavity flow: tangential motion outward to a boundary of stationary pulp; .(c) Tangential-Cavity flow: tangential motion fills the chamber; (d) Flooding: when smaller quantities of gas are present the flow pattern may cease development at (b) or (c); (e) Outward radial flow: only observed for 1%< Cm < 4%; (f) Inward radial flow: sixfold symmetry produced by the six housing baffles. CHAPTER 3. DYNAMIC BEHAVIOUR OF PULP SUSPENSIONS 114 Figure 3.13: Fluid-like zone of pulp motion increases with shear rate. Here, in four frames taken from a motion picture film made at 300 pps, the radial extent of the flow in a 10% C m semi-bleached kraft pulp is distinctly visible due to an aqueous black dye initially placed adjacent to the rotor, (a) Yield Point, T = 10.9 N-m, (b) 950 rpm, T = 8.0 N-m, (c) 2150 rpm, T = 10.9 N-m, (d) 3700 rpm, T = 14.6 N-m. The bulk density of the suspension was 940 kg /m 3 and no flow transition was observed. Test PFD.124. made at 300 pps. Here an aqueous black dye was initially injected immediately adja-cent to the rotor prior to the test. As the zone of motion grew, the radial extent of dye penetration is distinctly visible in the photographs. A radial gradient of fibre motion existed in the active zone. The most intense motion was immediately adjacent to the rotor; motion decreased with radial distance to a rolling floe motion adjacent to the stationary pulp at the outer limit of the active zone. This steep radial velocity gradient was confirmed by analysis of a high speed motion film taken of this flow regime. A 5.94% Cm semi-bleached kraft pulp (SBK-2) CHAPTER 3. DYNAMIC BEHAVIOUR OF PULP SUSPENSIONS 115 Figure 3.14: Flow of a 5.94% Cm semi-bleached kraft pulp in the wide-gap configuration at 1230 rpm. Flow is primarily tangential with flow velocity decreasing rapidly with increasing radial distance. The pulp is largely stagnant 95 mm from the center of the fluidizer. Arrows are proportional to floe velocities. was filmed at 1230 rpm in the wide-gap configuration, and analysed as described in section G.2. Due to the opacity of the suspension, only floes adjacent to the lexan plates could be followed. Figure 3.14 shows the velocity vectors of approximately 50 fibre bundles tracked. The flow is predominantly tangential with a large velocity gradient in the radial direction. Observation of the entire film showed regions at the periphery of the active zone where fibre and floe motion occurred only intermittently, if at all. An attempt was made to predict the radial extent of suspension motion by equating the shear stress at the boundary between the active and stationary pulp with the yield stress of the suspension. A torque balance was made at the cavity interface, similar to that given by Solomon et al. [1981]. CHAPTER 3. DYNAMIC BEHAVIOUR OF PULP SUSPENSIONS 116 The surface area of the boundary between the active and stationary pulp is given by Sa = 2nraL (3.15) where ra is the radial extent of the active zone. The force at the boundary surface is F = Ty2nraL (3.16) and the torque on the shaft due to this force is T = Fra = Tv2irr?L (3.17) which can be rearranged to give 2-KTyL (3.18) The radius of the active zone and the torque were measured in a series of tests conducted with semi-bleached kraft pulp (SBK-4). These results are plotted in Figure 3.15 as ra vs. the value predicted from Equation 3.18. The suspension yield stress was estimated using Equation 2.15. Clearly the agreement with theory is only fair, and Equation 3.18 tends to underpredict the extent of the active zone. This result can be attributed, in part, to experimental inaccuracies in the data. Firstly, it was very difficult to measure the radial extent of the active zone accurately due to the non-uniform extent of motion clearly visible in Figure 3.13 and the difficulty determining the boundary between the moving and stationary pulp. At best, measurement of ra was only accurate to approximately ±10 mm. Secondly, the torque measurements were only accurate to ±0.6 N-m, and the values used for Ty are also subject to error. These experimental limitations are reflected by error bars on representative points in Figure 3.15. Thus, while the data do not entirely support this analysis, it is not possible to dismiss it without more accurate experimental data. CHAPTER 3. DYNAMIC BEHAVIOUR OF PULP SUSPENSIONS 117 Figure 3.15: Radial extent of active zone vs. that predicted using a torque balance. Experimental data are plotted against the radial extent of motion predicted with Equa-tion 3.18. The suspension yield stress was estimated using Equation 2.15. The error bars shown are based on the accuracy of measuring the torque and the radial extent of suspension motion. CHAPTER 3. DYNAMIC BEHAVIOUR OF PULP SUSPENSIONS 118 Equation 3.17 shows that the shaft torque at any rotational speed is expected to depend on ra and ry. As ry depends primarily on the volumetric concentration of the fibre suspension (see Equation 2.17), the experimental data were correlated in terms of T, Cv and ra by fitting to an empirical equation of the form T = aCvbrac (3.19) and gave T = l.06C™7r™* r2 = 0.68 (3.20) The goodness of fit, as indicated by r 2 , is poor. However, this is expected due to the experimental limitations mentioned above. This equation correctly indicates that the shaft torque increases with both the radial extent of the active zone and the volumetric concentration of the pulp suspension. In a standard test, the increase in torque with radial distance was manifested as an increase in torque with rotational speed. In many cases, particularly for low consis-tency suspensions, the torque vs. rotational speed curve was parallel to that for water. However, more commonly the pulp suspension curve lies initially above that for water, crosses the water curve at some point, and then continues to increase but falls signif-icantly below the water curve. The torque at any rotational speed depended on the radial extent of motion in the chamber, the suspension rheology (i.e. yield stress) and the density of the suspension in the rotor vicinity (discussed further in section 3.4.2.7). The point at which the pulp suspension curve crossed that of water does not appear to have any special significance. 3.4.2.4 F l ow Trans i t i on When the active zone approached the housing wall, fibre motion was primarily tangen-tial and exhibited an extreme radial gradient of velocity as illustrated in Figure 3.12(c). By further increasing the rotational speed of the rotor (often only a very slight increase CHAPTER 3. DYNAMIC BEHAVIOUR OF PULP SUSPENSIONS 119 in rotational speed was required once flow had reached the vessel wall) two distinct changes in flow behaviour were observed. For tests at low consistency, the first observed change was establishment of a flow pattern dominated by radial outward flow when viewed from the front, as illustrated in Figure 3.12(e). This flow only existed over a relatively narrow range of rotational speed and was detected only in suspensions of mass concentration less than approximately 4%. The flow was ordered. A turbulent zone extending 10-20 mm from the housing wall could be seen in the tests. The extent of this turbulent region increased with increasing rotational speed, and was likely caused by fibre impingement on the outer cylinder wall. Observation along the horizontal axis revealed axial flow toward the center of the fluidizer from both ends of the housing as illustrated in Figure 3.16(a). A further increase in rotational speed resulted in another flow transition and the establishment of a flow pattern dominated by inward radial flow when viewed from the front. Pulp suspensions at all mass concentrations exhibited this radial inward flow pattern. The transition to this flow was readily apparent, and although it was reproducible, its onset varied from run to run and sometimes took up to one second to occur. Once established, the flow pattern did not change, even at the highest rotational speed attained in the fluidizer. When viewed from the side, this flow pattern appeared to be an inversion of the previous pattern, as illustrated in Figure 3.16(b). 3.4.2.5 P o s t - T r a n s i t i o n R e g i m e Analysis of the post-transition flow pattern was made by means of video tapes and high speed cinematography. These permitted a detailed qualitative assessment of flow in the fluidizer, and showed several interesting phenomena. Firstly, the flow was radially inward as described earlier. It appeared to be reasonably ordered and exhibited six-fold symmetry corresponding to the six compartments produced by the baffles on the housing. As required by continuity, there was also a strong axial component to the flow. CHAPTER 3. DYNAMIC BEHAVIOUR OF PULP SUSPENSIONS 120 REAR REAR FRONT a FRONT b Figure 3.16: Post-transition flow profile viewed through the side observation port, midway along the housing axis. The location of this viewing port is shown in Figure A.5. (a) Radially outward flow (viewed from the front of the fluidizer) becomes axial motion near the housing wall. This flow converges halfway down the longitudinal dimension of the fluidizer chamber, (b) Radially inward flow (viewed from the front) also adopts an axial profile at the housing wall midway along the longitudinal dimension of the fluidizer. However, the flow appears from the center of the fluidizer chamber. These two flow profiles appear to be inversions of one another. The direction of rotor rotation is indicated by the broad arrow. CHAPTER 3. DYNAMIC BEHAVIOUR OF PULP SUSPENSIONS 121 The pulp suspension appeared in a zone halfway down the longitudinal dimension of the rotor, with half the flow moving forward to the front of the fluidizer chamber, while the other half moved to the back of the chamber as illustrated in Figure 3.16(b). Even though the suspension behaved in a fluid-like manner, floes could still be seen moving in the flow. For one particular test condition (5.94% SBK-2 at 2500 rpm), floe motion observed on a high speed film taken at between 1000 and 5000 pps was digitized, allowing estimation of velocities in the post-transition flow pattern. As floes could be seen appearing and disappearing in the flow, tracking them was difficult. Figure 3.17 gives the velocity vectors of approximately 100 fibre bundles that could be tracked. These data show that the flow is primarily radially inward, originating at the housing wall and moving towards the centre of the chamber. There are some regions of tangential backflow near the outer wall adjacent to the baffles. While the rotor peripheral speed was 26.2 m/s, the average velocity of the fibre bundles tracked was only 1.5-2.5 m/s. As the method used to determine floe velocity only permitted calculation of an average velocity over periods up to 0.1 second, it was not possible to quantify the turbulence in any way. However, a number of flow visualization studies were made in which fibre tracers were added to pulp in the fluidizer chamber to assess mixing in the fluidizer. In the first test, 0.016 kg of red dyed nylon fibre (I = 1.0 mm d = 0.0431 mm) was added as a tracer to 3.16 kg of a 9.7% Cm semi-bleached kraft pulp suspension. The red fibre was placed at the lower wall of the fluidizer housing and a standard test (PFD.089) conducted. No red fibres were seen in the suspension until motion had reached the outer wall. However, after the point of flow transition the red fibres were quickly distributed throughout the suspension. High speed cinematography showed that approximately 1.4 seconds elapsed between the first detection of red fibres in the flow and the achievement of a uniform distribution of fibres throughout the suspension. Figure 3.18 shows the uniform macroscale distribution of red fibres following the test, CHAPTER 3. DYNAMIC BEHAVIOUR OF PULP SUSPENSIONS 122 Figure 3.17: Flow of a. 5.94% C7m semi-bleached kraft. pulp in the wide-gap configuration at 2500 rpm. Post-transition flow characterized by inward radial motion when viewed from the front. Arrows are proportional to floe velocities. CHAPTER 3. DYNAMIC BEHAVIOUR OF PULP SUSPENSIONS 123 Figure 3.18: Red fibres are distributed uniformly on the macroscale following a standard test run. Here a 0.016 kg of red nylon fibre was placed at the bottom of the housing prior to the test. The uniform distribution of fibres occurred approximately 1.4 seconds after the onset o f r a d i a l flow in the housing. Test PFD.089. CHAPTER 3. DYNAMIC BEHAVIOUR OF PULP SUSPENSIONS 124 Figure 3.19: Red fibres are distributed uniformly on the fibre-scale following a standard test (PFD.089). The red fibres are approximately 1 mm in length. while Figure 3.19 indicates that, even at the fibre-scale, fibres are distributed uniformly. In another set of tests, black-dyed fibres (SBK-2 dyed with Tintex fabric dye) were packed in a 5-10 mm deep layer at the back wall of the fluidizer housing. Semi-bleached kraft (SBK-2) at 9.7% Cm (PFD.087) and 10.6% Cm (PFD.123) filled the rest of the chamber. A standard test run was conducted. It was not until after the point of flow transition that the dark fibres began to appear at the front of the chamber. Again, the tracer distribution appeared to be uniform approximately 1.5 seconds after the first black fibres were detected at the front. These tests indicated that the good mixing observed in the pulp fluidizer was due to the flow pattern created in the vessel chamber. Although relative fibre motion existed in the active zone during rotor acceleration, flow was at first tangential with little or no axial component. It was not until the flow transition and establishment of radial CHAPTER 3. DYNAMIC BEHAVIOUR OF PULP SUSPENSIONS 125 and axial flow components that the entire vessel contents became mixed. Floes were disrupted in the post-transition flow pattern as indicated by the uniform distribution of the fibre tracer at the fibre-scale. The completion of the post-transition flow pattern did not seem to occur at a specific point on the torque vs. rotational speed curve. However, it usually followed a change in the slope of the torque vs. rotational speed curves by approximately 500 rpm (roughly one second under the standard test conditions). The change in slope can be attributed to the increased momentum transfer caused by the radial and axial flow associated with the post-transition regime, while the lag in detection of the flow transition can be attributed to the finite time taken for the flow pattern to become established. 3.4.2.6 P r e d i c t i o n o f t h e F l o w T r a n s i t i o n Various criteria were examined to predict and explain the occurrence of the flow tran-sition in the pulp fluidizer. As the post-transition flow pattern was similar to that for Taylor vortex flow [Taylor, 1923; Kataoka, 1986], it was one method examined. Taylor vortex flow occurs when the rotational speed of the inner cylinder of a concentric cylinder device is increased beyond a certain critical value. Once this occurs, the basic laminar axisymmetric flow (Couette flow) becomes unstable due to the larger centrifugal force pv2/r near the inner cylinder. A flow transition occurs which leads to the development of a second stable flow known as Taylor vortex flow. This flow is characterized by pairs of torroidal rings of fluid stacked along the cylinder axis with fluid flow opposed in each ring pair. The torroidal motion of the fluid elements causes highly effective mixing, and each vortex pair can be regarded as a well-mixed batch vessel. The change in mean motion after the onset of Taylor vortex flow also increases the torque on the inner cylinder. Taylor vortex flow offers a convenient qualitative explanation for the onset of flow transition in the pulp fluidizer, the form of the post-transition flow pattern, and the CHAPTER 3. DYNAMIC BEHAVIOUR OF PULP SUSPENSIONS 126 increase in shaft torque observed near the transition. As the onset of Taylor flow can be predicted given fluid properties and the concentric-cylinder geometry [Taylor, 1923; Kataoka, 1986], it was hoped that it could be used to predict apparent fluid properties of pulp suspensions. However, the dissimilarities between our system and those that have been characterized by Taylor vortex flow are quite substantial. 1. A pulp suspension, particularly at higher consistencies, is highly non-Newtonian. It is solid-like below the yield stress. 2. While the presence of baffles on the housing wall, and lugs on the rotor, were required to impose a no-slip condition at these surfaces, they alter the flow pattern within the concentric-cylinder vessel. The work on Taylor vortex flow presented in the literature has been for smooth walled vessels. 3. The equations used to predict the onset of Taylor vortex flow are for narrow gap configurations. In the pulp fluidizer not only was the gap width wide, but the presence of lugs and baffles mean that its width was variable. 4. Newtonian fluids (water and glycerol) did not display a Taylor transition in the pulp fluidizer. While the housing baffles were required to prevent the fibres from slipping at the boundary, for Newtonian fluids they influenced the flow pattern soon after rotor movement begain. The flow transition occurred shortly after suspension flow reached the housing wall. Thus, the most probable explanation for its occurence is that the housing baffles trig-gered the transition by imposing a radial component to the flow that did not exist in the tangential-cavity regime. If this is the case, then Equation 3.20 with ra equal to 0.1 m (the radial distance to the tip of a housing baffle in the wide-gap configuration) should predict the occurrence of the flow transition. This gives: T = 0 . 1 4 C 1 - 2 7 (3.21) CHAPTER 3. DYNAMIC BEHAVIOUR OF PULP SUSPENSIONS 127 The experimental data for the flow transition in the wide-gap configuration (Table F.2) were fitted to T = aC* and gave T = 0.20C,,1-56 r 2 = 0.94 (3.22) The error associated with Equation 3.21 is largely due to the experimental error as-sociated with the data. The 95% confidence interval for b (0.88 < b < 1.66) includes the value correlated experimentally. Thus we can tentatively conclude that the flow transition occurs soon after the flow begins to interact with the housing baffles. 3.4.2.7 Phase Separation During all tests, high centrifugal forces segregated the pulp suspension with the gas phase collecting between the rotor lugs at the center of the fluidizer. Only a fixed volume of gas could be accommodated between the rotor lugs 1 before there was a significant reduction in momentum transfer to the pulp suspension resulting in a flooded condition. When this occurred, the torque levelled off although the rotational speed continued to increase. The torque vs. rotational speed could then fall significantly below that of water, as is evident in many of the torque vs. rotational speed curves shown thus far, including Figure 3.10. The power drawn by a mixing vessel decreases as the quantity of gas in the impeller region increases. This fact is well documented in the literature [Bates et al., 1966; Mann, 1983], although it is usually studied for continuous operations. The progressive loss in power with increasing gas flow to the impeller is descibed by Mann [1983]. " . . . A s the gas rate increases, a small vortex cavity forms behind each blade, being initiated by the trailing liquid vortices . . . At a higher gas rate the vortex cavities enlarge until they 'cling' behind the blades. Continuing increase in gas flow rate to the impeller results in the formation of a single 1The maximum volume of gas that can be accommodated by a rotor before it loses contact with the suspension is readily calculated by subtracting the rotor volume from the volume it would occupy if the grooves between the lugs were filled with metal. CHAPTER 3. DYNAMIC BEHAVIOUR OF PULP SUSPENSIONS 128 large cavity which can migrate from blade to blade in a semi-stable but psuedo-random fashion. Further gas feed causes the number of large cavities to increase until there is a large cavity behind every blade. Thereafter the large cavities can bridge between all the blades giving rise to a flooded condition. As the cavities become larger and larger the area for liquid outflow radially is more and more blocked, the liquid 'pumping' rate is diminished and the power drawn is correspondingly reduced." In the batch tests conducted here, an increase in gas phase volume is analogous to an increased gas flow rate. To avoid creation of a flooded condition it was necessary to minimize the amount of air contained in the fluidizer chamber. This was particularly true for suspensions above 8% Cm where the gas phase can be substantial [Dosch et ai, 1986]. Special efforts were taken to achieve this. The fluidizer chamber was initially packed as full as possible (which required compression of M C pulp suspensions) and a test conducted. If a significant gas phase existed, the torque would level off at some point in the test (usually above 3000 rpm), and void spaces could be seen behind the rotor lugs following the test. In these cases, the gas spaces were packed with additional pulp and the test conducted again. For higher consistency suspensions (above 13% C m ) , it was necessary to repeat this procedure up to three times to prevent the torque vs. rotational speed curve from levelling off below 5000 rpm as shown in Table 3.2 for tests PFD.048 through PFD.065. The point at which the torque levelled off depended on the total gas content of the pulp suspension and the amount of gas that could be accommodated between the rotor lugs. For rotor PF2 , used in the tests given in Table 3.2, this volume was calculated to be 2.2 X 1 0 - 4 m 3 . The volume of gas present in the fluidizer and the mass concentration of the sus-pension strongly affected the extent to which the flow pattern would develop in the chamber. As illustrated in Figure 3.12(d), flow development would cease if the rotor became flooded with gas. In the tests conducted, this was observed to occur at any point before the flow transition and depended on the gas content in the system. CHAPTER 3. DYNAMIC BEHAVIOUR OF PULP SUSPENSIONS 129 Table 3.2: Phase separation in dynamic tests. Semi-bleached kraft (SBK-2) in the wide-gap configuration. Rotor PF2 . Test Identification Fibre Mass Concentration Cm,% Gas Volume m 3 (104) Gas Volume/ Available Volumef Point at which Torque Levels Off rpm PFD.048 2.0 0 0 -PFD.049 2.0 0.2 0.09 -PFD .050 4.0 0.4 0.19 -PFD.051 4.0 0.4 0.19 -PFD.052 6.0 3.3 1.47 -PFD.053 8.0 2.2 0.97 2400 PFD.054 8.0 0.9 0.40 -PFD.055 9.7 1.7 0.52 2800 PFD.056 9.7 0.4 0.18 -PFD.057 13.1 2.8 1.27 2600 PFD.058 13.1 0.9 0.42 4300 PFD.059 13.1 0 0 -PFD .060 14.9 3.0 1.34 3800 PFD .061 14.9 1.3 0.57 4400 PFD.062 14.9 0.4 0.17 4700 PFD.063 16.0 4.1 1.82 3300 PFD.064 16.0 3.0 1.33 4600 PFD.065 16.0 2.1 0.96 -f The volume of gas that could be accomodated between the rotor lugs before the rotor lost contact with the pulp suspension. CHAPTER 3. DYNAMIC BEHAVIOUR OF PULP SUSPENSIONS 130 Once post-transition flow was established in the fluidizer chamber the vessel contents were well mixed. In most cases the torque vs. rotational speed curve was below that for pure water. This was attributed to the lower suspension density in the vicinity of the rotor caused by the presence of gas. Equation 3.14 shows that power expenditure in the turbulent regime depends only on the density of the media mixed. The validity of this equation was demonstrated by tests conducted with water (p = 1000 kg/m 3 ) and glycerol (p = 1250 kg/m 3 ) in the pulp fluidizer. As shown in Figure 3.20, within experimental error, the torque measured at any rotational speed (above approximately 250 rpm) was in the same ratio as that of the fluid densities: 1 to 1.25. When the suspension density in the rotor vicinity falls below that of water, the torque required at any rotational speed also decreases. In most tests reported here, rotor PF2 with the ability to accommodate 2.2 x 1 0 - 4 m 3 of gas was used. Rotor P F 4 , having the same outside dimensions as rotor PF2 , but deeper lugs and the ability to accommodate 4.0 x 10~ 4 m 3 of gas, postponed or prevented the levelling-off of the torque vs. rotational speed curves. Nevertheless, the torque could still fall below that for water due to reduced suspension density in the rotor vicinity caused by gas in the suspension. 3.4.3 N a r r o w - G a p E x p e r i m e n t s 3.4.3.1 T o r q u e v s . R o t a t i o n a l S p e e d C u r v e s Torque vs. rotational speed curves for a series of tests in the narrow-gap configuration (see Figure 3.3) using SBK-2 are given in Figures 3.21 and 3.22. These curves display some of the features observed in the wide gap experiments: an increasing yield stress with increasing pulp mass concentration and a rapid drop in torque after the rotor began to move. However, these curves also show a dramatic torque increase close to the critical rotational speed at which the flow transition is visually observed. The CHAPTER 3. DYNAMIC BEHAVIOUR OF PULP SUSPENSIONS 131 o o CO cr1 o 100 A n g u l a r V e l o c i t y , r a d / s 200 300 400 500 -Water 'i' G l y c e r o l - A -' 1 / ' i r 1 / i y j / • / 1.25±0.05 ' 1 ^/ /' 1 / S' ^ 1 . 3 8 * 0 . 1 0 / y 1.42±0.20 1000 2000 3000 R o t a t i o n a l S p e e d , r p m 4000 5000 Figure 3.20: Torque vs. rotational speed curves for water (PFD.047) and pure glycerol (PFD.129) tested in the pulp fluidizer. Rotor P F 2 , Housing P F H 1 . The ratio of the torques (glycerol/water) are given at 1000 rpm intervals, together with the estimated error. CHAPTER 3. DYNAMIC BEHAVIOUR OF PULP SUSPENSIONS 132 A n g u l a r V e l o c i t y , r a d / s 0 100 200 300 400 500 in 0 1000 2000 3000 4000 5000 R o t a t i o n a l S p e e d , r p m Figure 3.21: Torque vs. rotational speed curves for SBK-2 in the narrow-gap configu-ration. Tests for 0% (PFD.109), 2% (PFD.099), 4% (PFD.100) and 6% (PFD.101) Cm are shown. The completion of the flow transition, as observed at the font face of the fluidizer, is indicated by a solid point on each pulp suspension curve. CHAPTER 3. DYNAMIC BEHAVIOUR OF PULP SUSPENSIONS 133 A n g u l a r V e l o c i t y , r a d / s 0 100 200 300 400 500 0 1000 2000 3000 4000 5000 R o t a t i o n a l S p e e d , r p m Figure 3.22: Torque vs. rotational speed curves for SBK-2 in the narrow-gap configura-tion. Tests for 0% (PFD.109), 8.3% (PFD.102), 9.2% (PFD.103) and 11.7% (PFD.106) C m shown. The completion of the flow transition, as observed at the font face of the fluidizer, is indicated by a solid point on each pulp suspension curve. CHAPTER 3. DYNAMIC BEHAVIOUR OF PULP SUSPENSIONS 134 regimes of suspension behaviour observed during a standard test in the narrow-gap configuration are illustrated in Figure 3.23 and described below. 3.4.3.2 Y i e l d The suspension exhibited a yield stress. Fibres throughout the entire volume moved slightly during the 10-25° of rotor movement that preceeded continuous rotation as illustrated in Figure 3.23(a). 3.4.3.3 T a n g e n t i a l - C a v i t y R e g i m e A shear plane was created during rotor acceleration. Intense fibre motion occurred in the narrow 5 mm gap between the rotor and housing baffles, while the suspension in a zone approximately 10 mm from the housing wall (contained by the baffles) remained stationary as illustrated in Figure 3.23(b). As the shear rate increased, motion began to develop in the region of stagnant pulp between the housing baffles. Fibre floes at first moved tangentially with the rotor, squeezing by the housing baffles as illustrated in Figure 3.23(c). Motion reached the outer housing wall, although zones of restricted motion in the areas shielded by the baffles continued to exist. Wi th further increases in rotor speed, these zones of restricted motion began to develop what appeared to be radial components of velocity. As discussed earlier, this produces some axial flow, and fibre floes appeared from the interior of the chamber (Figure 3.23(e)). The flow at this point still existed in two distinct regions: a zone of radial floe motion confined between adjacent baffles, and a zone of intense motion in the gap adjacent to the rotor. In this tangential-cavity regime the torque increased only slightly due to phase separation which reduced suspension density in the rotor vicinity. Therefore, the torque vs. rotational speed curves for the suspensions could fall significantly below that of the water curve as illustrated in Figure 3.22. CHAPTER 3. DYNAMIC BEHAVIOUR OF PULP SUSPENSIONS 135 Figure 3.23: Regimes of semi-bleached kraft suspension behaviour in the narrow-gap configuration: (a) Yield: void spaces appear behind the rotor lugs; (b) Formation of a shear plane: intense motion in the area influenced by rotor lugs and no motion in the stagnant area shielded by baffles; (c) Tangential-cavity flow: 'tangential' flow fills chamber; (d) Flooding: when a smaller quantity of gas is present the flow pattern may cease development at (b) or (c); (e) Inward radial flow; and (f) Post-transition flow: intense flow fills the fluidizer chamber. The flow pattern is unknown, although it likely involves substantial axial and radial components as illustrated in Figure 3.12(e) and (f). CHAPTER 3. DYNAMIC BEHAVIOUR OF PULP SUSPENSIONS 136 3 . 4 . 3 . 4 F l o w T r a n s i t i o n At a critical rotation speed, denoted by the solid points in Figures 3.21 and 3.22, the en-tire vessel contents became involved in intense flow. The torque increased dramatically to supply the energy required to maintain the post-transition flow pattern. However, because of the restricted area between the rotor and housing, it was difficult to deter-mine the exact nature of the mean flow pattern. There did appear to be an axial flow component judging from a slight outward bending of the Lexan cover plate. The point of observed flow transition did not always correspond precisely with the point at which the torque began to increase rapidly as shown in Figure 3.22. At times the flow transition occurred at slightly higher rotational speeds. This was attributed to experimental limitations in timing the transition (as the torque could rise from 10 to 30 N-m in 0.2 seconds) and the fact that the transition took a short but finite time to occur. Therefore, the dramatic increase in torque appeared to be due to the establishment of the new flow pattern in the fluidizer chamber. 3 . 4 . 3 . 5 P h a s e S e p a r a t i o n As in the wide-gap configuration, high centrifugal forces segregated the pulp suspen-sion from the gas phase which collected around the rotor lugs. As described in sec-tion 3.4.2.7, if sufficient gas accumulated around the rotor, momentum transfer to the pulp suspension was decreased and further flow development could cease. Because the total volume of the narrow-gap chamber was only 7.0 x 1 0 - 4 m 3 , less pulp and conse-quently less air was present for a pulp of given mass concentration. Phase separation that resulted in the formation of a shear plane with little motion in the regions near the baffles (as illustrated in Figure 3.23(b)) was only observed for pulp suspensions with very high gas contents, i.e. 16% Cm semi-bleached kraft. CHAPTER 3. DYNAMIC BEHAVIOUR OF PULP SUSPENSIONS 137 3.4.4 F l o e B e h a v i o u r Visual observation of pulp suspension behaviour in the wide-gap configuration sug-gested the presence of a gradient of floe size in the tangential-cavity regime. Consistent with the large radial shear gradient discussed in section 3.4.2.3, floes appeared relatively large near the housing wall and smaller in size near the rotor. However, high-speed mo-tion picture films taken with the Hycam (5.94% semi-bleached kraft pulp, 1230 rpm, tangential-cavity regime) showed that despite the large shear gradient, floe size dis-tribution throughout the chamber was substantially uniform: 6 ± 1 mm. Individual floes were observed to deform, particularly in the rotor proximity, but they persisted as entities in the flow. A high-speed (5.94% semi-bleached kraft pulp, 2500 rpm) film taken of the post-transition regime showed a floe size similar to that measured in the tangential-cavity regime: 5 ± 1 mm. The error associated with the floe size measure-ments (between 20-40%) precludes a more detailed comparison of floe size. However, these measured floe sizes are consistent with earlier findings that floes are one to two fibre lengths in size [Kerekes et al., 1985]. 3.4.5 D y n a m i c B e h a v i o u r o f D i f f e r e n t P u l p s The torque vs. rotational speed curves for mechanical pulp suspensions displayed similar characteristics to those found for semi-bleached kraft pulps. However, in agreement with Backlund et al. [1984], the mechanical pulps did not exhibit a dramatic torque drop when the rotor first began moving. Instead, the torque remained fairly constant or increased slightly up to the point of flow transition as shown in Figure 3.24. A tangential-cavity and post-transition regime were present in tests conducted with the mechanical pulps. The observed completion of the flow transition (marked on the curves given for stone groundwood pulp (SGW-1) in Figure 3.25) occurred after the torque had already begun to increase. This is again attributed to the short but finite CHAPTER 3. DYNAMIC BEHAVIOUR OF PULP SUSPENSIONS 138 A n g u l a r V e l o c i t y , r a d / s 0 100 200 300 400 500 1 I I I I L_ R o t a t i o n a l S p e e d , r p m Figure 3.24: Torque vs. rotational speed curves made with 10% Cm semi-bleached kraft (PFD.055), stone groundwood (PFD.069) and thermomechanical pulps (PFD.071). Tests were conducted in the wide-gap configuration ( P F 2 / P F H 1 ) with water (PFD.047) used as the reference curve. The completion of the flow transition, as observed from the front face of the fluidizer, is marked on each pulp suspension curve with a solid point. These points lag the change in slope of the torque vs. rotational speed curves as discussed in section 3.4.2.5. CHAPTER 3. DYNAMIC BEHAVIOUR OF PULP SUSPENSIONS 139 A n g u l a r V e l o c i t y , r a d / s 0 100 200 300 400 500 I I I I I 0 1000 2000 3000 4000 5000 R o t a t i o n a l S p e e d , r p m Figure 3.25: Torque vs. rotational speed curves made with stone groundwood pulp in the wide-gap configuration: 0% (PFD.047), 6.1% (PFD.081), 9.0% (PFD.083) and 10% (PFD.070). The completion of the flow transition, as observed at the front of the fluidizer, is marked on each pulp suspension curve with a solid point. CHAPTER 3. DYNAMIC BEHAVIOUR OF PULP SUSPENSIONS 140 time taken for the post-transition flow pattern to become fully established. 3.5 C o m p a r i s o n w i t h Resu l ts o f Gu l l i chsen and H a r k o n e n Our findings show a number of distinct differences from those reported by Gullichsen and Harkonen [1981]: 1. The Gullichsen and Harkonen tests on pine kraft pulp (Figure 3.1) do not show the dramatic drop in torque following initial rotor movement found here. Instead, it was reported that the torque remained relatively constant as rotational speed was increased, similar to the behaviour found here for mechanical pulps (Figure 3.24). The differences in pulp properties between the pine kraft used by Gullichsen and Harkonen and the semi-bleached kraft used here would not be sufficient to account for this discrepancy. 2. The onset of "fluidization" observed by Gullichsen and Harkonen is described as "the point at which the whole vessel content comes into a vigorous state of turbulence". However, it would appear that they observed the flow transition which was described in section 3.4.2.5. We do not ascribe this to a transition from solid-like to fluid-like behaviour, i.e "fluidization", but rather to a signifi-cant change in the flow pattern of a pulp suspension already exhibiting fluid-like behaviour. The post-transition flow pattern was characterized by regions of well-defined mean suspension motion. While there was undoubtedly turbulence, or at least turbulent regions within the chamber, the intensity of the turbulence was not known. 3. The onset of "fluidization" was observed by Gullichsen and Harkonen to occur when the torque vs. rotational speed curve for the pulp suspensions were close to the curve for water. In our experiments no major flow change occurred at this CHAPTER 3. DYNAMIC BEHAVIOUR OF PULP SUSPENSIONS 141 point, although the flow transition did occasionally occur near the water curve. 4. Gullichsen and Harkonen did not observe the levelling off of the torque vs. rota-tional speed curves which we observed and attributed to phase segregation. This may be due to two factors. Firstly, the maximum rotational speed reached in the Gullichsen and Harkonen apparatus (2500 rpm) was much lower than ours (5000 rpm) and may not have been sufficient to produce phase segregation. In our tests the torque vs. rotational speed curve levelled off at speeds above 2500 rpm. Secondly, Gullichsen and Harkonen did not record the bulk density or void frac-tion in their tests and it is therefore not possible to determine if phase segregation was a factor. 3.6 C h a r a c t e r i z a t i o n o f S u s p e n s i o n F l u i d - L i k e B e h a v i o u r In order to characterize the fluid-like behaviour of pulp suspensions, it is desirable to describe the suspensions in terms commonly associated with fluids. One key chacteristic of a fluid is that, when caused to flow, the shear stress and shear rate are related by an apparent or effective viscosity (fia = r /T ) . If pulp suspensions truly exhibit fluid-like behaviour, it should be possible to assign an apparent viscosity to the suspension at given shear rates. The unique nature of M C pulp suspensions makes viscosity measurement using conventional methods impossible. Consequently, two methods were explored as a means of estimating an effective suspension viscosity: power number at the point of flow transition and power dissipation. While these methods have shortcomings, which will be discussed below, they were used to determine if an appropriate range of apparent viscosity could be defined. CHAPTER 3. DYNAMIC BEHAVIOUR OF PULP SUSPENSIONS 142 i i i 1111 • = P F 2 / P F H 1 A = P F 2 / P F H 2 • 1 1 ' 1 " " • i i • 111 i i i i 111 II i i i i ii i iii i id i o 2 i o 3 i o 4 R e y n o l d s N u m b e r , N R E 10° 10" Figure 3.26: Power number vs. Reynolds number for the pulp fluidizer obtained with water (NRe > 104) and glycerol (NRe < 10 3). Wide-gap configuration: P F 2 / P F H 1 , and narrow-gap configuration: P F 2 / P F H 2 . The error bars shown are based on the accuracy of measuring the torque. 3.6.1 P o w e r N u m b e r D u r i n g D y n a m i c P u l p T e s t s As described in section 3.2.4, the pulp fluidizer is in essence a mixer and can be char-acterized in terms of a power number. The power number for the fluidizer was deter-mined for Newtonian fluids (water and pure glycerol) in the wide-gap (50 mm gap) and narrow-gap (5.0 mm gap) configurations. The results are given in Figure 3.26. The transition from "laminar" to "turbulent" flow, or more precisely from viscous to inertia dominated flow, occurred in the range 10 < JV#e < 1,000, in agreement with results for other mixers [Bates et al., 1966; Skelland, 1983]. In the viscous regime, the power number is viscosity dependent and therefore the plot of Np versus Nne for Newtonian fluids given in Figure 3.26 can be used to assign CHAPTER 3. DYNAMIC BEHAVIOUR OF PULP SUSPENSIONS 143 Table 3.3: Apparent viscosity at the point of flow transition for semi-bleached kraft pulp (SBK-2) in the wide-gap configuration determined using power number correlations. Cm Tests Used Apparent Viscosity, fia, Pa-s (%) (PFD.xxx) Average Range 2 048, 049, 117, 118 0.74 0.15-1.5 2.9 119, 120 0.78 0.5-1.2 3.9-4 050, 121 0.84 0.32-1.3 an apparent viscosity to a pulp suspension. This was achieved by calculating Np at the point where the pulp suspension was in complete motion within the fluidizer chamber. If it was greater than that given by the flat portion of the curves, iVp.turb, Figure 3.26 was used to establish NRC for the suspension, and an apparent viscosity was calculated. Apparent viscosities were estimated using this procedure for semi-bleached kraft pulp suspensions in the wide-gap configuration at the onset of flow transition. The results are given in Table 3.3. Note that it was only possible to determine an apparent viscosity for mass concentrations up to 4%. Above 4% C m the power number was below Wp.turb for the Newtonian fluids. This was most likely due to phase segregation that reduced the suspension density in the vicinity of the rotor, although it may be related to limited vessel baffling [Skelland, 1983]. For those cases where an apparent viscosity was estimated, the error was very large and arose primarily from the torque measurements. , 3.6.2 P o w e r a t t h e P o i n t o f F l o w T r a n s i t i o n The power required to maintain motion in a fluid, in this case a pulp suspension, is ultimately dissipated as heat through viscous dissipation in small scale fluid motion. Thus, power dissipation may be used to estimate the apparent viscosity of a pulp suspension. CHAPTER 3. DYNAMIC BEHAVIOUR OF PULP SUSPENSIONS 144 The power dissipated per cubic metre, e, is calculated using 2TVNT fiT (3.23) V V The power dissipated in the Gullichsen and Harkonen [1981] tests at the point of "com-plete turbulence" is compared with that for SBK-2 at the point of the flow transition to radial motion 2 in Figure 3.27. Linear regression techniques yielded the following correlation for the results of Gullichsen and Harkonen: e = 342.9C m 3 3 8 r 2 = 0.947 (3.24) The data for the wide-gap configuration in this study (PF2 /PFH1) gave e = 7.46 x 1 0 3 C m 2 5 4 r 2 = 0.938 (3.25) For the narrow-gap configuration ( P F 2 / P F H 2 ) , where e was determined at the point where the sudden change in the torque vs. rotational speed curves occurred, e = 2 . 6 9 x l 0 4 C m 2 4 1 r2 = 0.980 (3.26) The power dissipated in the wide and narrow-gap configurations at the point of flow transition lie between the results for "fluidization" measured by Gullichsen and Harko-nen [1981] and estimated by Wahren [1980], as shown in Figure 3.27. In our tests e oc C m 2 " 5 , while for the Gullichsen and Harkonen tests a greater dependence on pulp concentration was obtained. The differences in e measured for each rotor/housing com-bination can be explained by reference to Equation 3.12 which shows that the power number depends on the geometrical parameters of the mixer. For the Gullichsen and Harkonen tests, the smaller number of impeller lugs and housing baffles may account 2The first appearance of a radial flow pattern, which for pulp suspensions below 4% Cm was an outward radial pattern and for suspensions greater than 4% Cm was an inward radial pattern, was used in the correlations for the wide-gap configuration. The flow patterns are likely inversions of one another (see section 3.4.2.4). In the case of the narrow-gap configuration it was not possible to determine the nature of the flow pattern following the flow transition. CHAPTER 3. DYNAMIC BEHAVIOUR OF PULP SUSPENSIONS 145 Figure 3.27: Power dissipation required for "fluidization" estimated by Wahren [1980] and measured by Gullichsen and Harkonen [1981] compared with that measured at the point of flow transition in the wide and narrow-gap configurations. CHAPTER 3. DYNAMIC BEHAVIOUR OF PULP SUSPENSIONS 146 for the lower power measured at any pulp concentration. As mentioned previously, the high dependence of e on CM in Wahren's estimate is likely due to his choice of the viscosity of water to characterize pulp suspensions (see section 3.2.2). By combining the data for the onset of flow transition for all tests made in this study, the following correlation, which accounted for the difference in mixer geometry, was obtained e = 4.49 x 1 0 4 C m 2 - 4 8 (=2-) r2 = 0.900 (3.27) This equation covers the range 1.3 < DT/D < 3.14. Equation 3.27 indicates that the occurrence of the flow transition, while greatly dependent on pulp mass concentration, is also dependent on the geometry of the test vessel. By taking the limit of Equation 3.27 as DT/D —> 1, the dependence of the power dissipation on vessel geometry was eliminated. Here e = 4 . 4 9 x l 0 4 C m 2 - 4 8 ( 3.28) We can assign an apparent viscosity to a semi-bleached kraft pulp at the point of flow transition using an analysis proposed by Wahren (see section 3.2.2). In isotropic turbulence, the power dissipation can be related to small-scale fluid motion [Hinze, 1975]. u'2 e = 15 / *— (3.29) A s where u'/\g is the turbulent shear rate, T. This expression may be roughly correct for anisotropic turbulence due to the nearly isotropic nature of the small scales that contribute to u' [Reynolds, 1974]. Assuming that r = fiaT we obtain 15r 2 = — (3.30) Substitution of Equation 3.28 for e and Equation 2.14 for r in Equation 3.30 gives the following approximate expression for the apparent viscosity of a pulp suspension fia = 2.33 x 1 0 - 2 C m 3 ' 1 0 (3.31) CHAPTER 3. DYNAMIC BEHAVIOUR OF PULP SUSPENSIONS 147 Table 3.4: Apparent viscosity of semi-bleached kraft at the point of flow transition determined by mixer power number correlation and power dissipation. Pulp Apparent Viscosity, Pa-s Mass Using Mixer From Power Concentration Curves and Dissipation C m , % NP 1 - 0.02 2 0.15-1.5 0.20 4 0.32-1.2 1.7 6 - 6.1 8 - 15 10 - 29 12 - 52 where fia is in Pa-s and Cm is in percent. 3.6.3 C o m p a r i s o n o f P u l p S u s p e n s i o n V i s c o s i t i e s E s t i m a t e d The apparent viscosity of a semi-bleached kraft pulp has been determined at the point of flow transition using the two different techniques described above. These results are summarized in Table 3.4 and compared with literature correlations in Figure 3.28. As each method has some serious shortcomings, which are lised below, the data can offer no more than an approximate estimate of the apparent viscosity of pulp suspensions. 1. The viscosity determined using the mixer curves varied over a wide range due to the large error in torque measurements at low rotational speeds. Further, where Cm > 4.0%, the Power number was less than that measured for Newtonian fluids due to the presence of gas in the suspension. This uncertainty casts doubt on the apparent viscosities estimated at 2 and 4% C m . 2. The viscosities estimated using power dissipation show that fia oc C m 3 1 0 . While the post-transition flow in the fluidizer is unlikely to be isotropically turbulent, CHAPTER 3. DYNAMIC BEHAVIOUR OF PULP SUSPENSIONS 148 i i i i i ITTT— ~ r — r - p t i i i i i i i i i i i i i. I Brodnvan / Hashin • 10"3 10"2 10"' 10° V o l u m e F r a c t i o n , C v Figure 3.28: Relative viscosity determined for semi-bleached kraft pulp compared with literature correlations (See section 3.2.3 and Figure 3.2). Apparent viscosities deter-mined using: O = power number correlations, • = power dissipation. CHAPTER 3. DYNAMIC BEHAVIOUR OF PULP SUSPENSIONS 149 the index on consistency will remain the same. Thus, in agreement with the theoretical curves of Brodnyan and Fedors, pulp suspension viscosity shows a dramatic increase in the medium consistency range which corresponds to the increasing solid-like nature of the suspension at high solids content. 3.7 S u m m a r y and Conc lus ions 1. Once rotor motion had been initiated in the pulp fluidizer, pulp suspensions exhibited two distinct regimes of behaviour. The first was a tangential-cavity regime in which pulp moved primarily in tangential flow in a cavity surrounded by stagnant pulp. The size of this cavity grew with increasing shear rate. When pulp motion extended to the outer housing wall, a flow transition occurred, ap-parently triggered by the interaction of the mean flow with the housing baffles. The subsequent post-transition regime exhibited strong radial and axial flow. The suspension composition and the geometry of the concentric cylinder tester influenced flow development and the point of transition from one regime to the other. 2. The gas present in a pulp suspension is separated from the suspension at the high rotational speeds reached in the pulp fluidizer. The gas accumulated around the rotor and resulted in inefficient momentum transfer from the rotor to the pulp suspension. The lowering of suspension density in the rotor vicinity resulted in a relatively constant torque with increasing rotational speed. If sufficient gas was present in the suspension, the rotor could flood and flow development cease before the onset of the post-transition regime. The point at which this occurred depended on the quantity of gas in the suspension and design of the rotor. 3. The effectivness of mixing in the pulp fluidizer depended strongly on the nature of the flow pattern produced in the chamber. The post-transition flow pattern CHAPTER 3. DYNAMIC BEHAVIOUR OF PULP SUSPENSIONS 150 mixed the chamber contents very effectively at both the macroscale and fibre-scale. When a gas phase was present, it also appeared to be well mixed after establishment of the post-transition flow pattern. Mixing was much less effective in the tangential-cavity regime. 4. The onset of the flow transition was a distinct, reproducible event. It is likely what Gullichsen and Harkonen [1981] interpreted as the "onset of complete turbulence" or "fluidization". 5. The power (in W / m 3 ) required to attain flow transition in a concentric-cylinder device with six lugs and six baffles can be estimated using the equation: for 1.3 < DT/D < 3.14 and 1% < CM < 16%. The flow transition may not be attainable if the quantity of gas in the fluidizer chamber is sufficient to flood the rotor and prevent momentum transfer to the suspension. 6. A n attempt was made to assign an apparent viscosity to a medium consistency pulp suspension at the point of flow transition. While neither of the methods used to estimate the apparent viscosity were completely satisfactory, it would appear that a 10% CM semi-bleached kraft pulp has an apparent viscosity at the point of flow transition on the order of 29 Pa-s. 3.8 R e c o m m e n d a t i o n s f o r F u t u r e W o r k 1. Further effort should be made to obtain mean and turbulent velocity measure-ments from medium consistency pulp suspensions in the fluidizer (See Appendix G) 2. The comparison of pulp suspension fluid-like behaviour should be made on the ba-sis of equal fluid motion. This will require information on small-scale suspension 2.34 CHAPTER 3. DYNAMIC BEHAVIOUR OF PULP SUSPENSIONS 151 motion under various fluidizer operating conditions. 3. The dynamic behaviour of the mechanical and chemical pulps tested in the flu-idizer were different. Further work should examine the extent to which pulp properties influence flow behaviour in the fluidizer. The work could be extended to include man-made fibre suspensions where fibre properties are more uniform. Nomenc la tu re S Y M B O L D E F I N I T I O N U N I T S a constant as appropriate a outer diffusion boundary, Equation J . 3 m A aspect ratio, l/d dimensionless b, c, d constants dimensionless b inner diffusion boundary, Equation J . 3 m c residual concentration mole/l c' concentration fluctuation mole/1 initial concentration fluctuation mole/l c height of impeller above vessel floor m c instantaneous concentration mole/l C rms average concentration mole / l Cinit initial concentration mole/l Cm mass concentration or consistency fraction cv volumetric concentration fraction n ^ v ,max maximum volumetric concentration fraction d bubble, drop or fibre diameter m equivalent diameter of a bubble or drop m d32 Sauter mean diameter, ^?=i / YA=I m d-95 drop size below which 9 5 % of volume is found m D diameter, impeller diameter m 1 5 2 NOMENCLATURE 153 D diffusivity m 2 / s D e f F effective diffusivity m 2 / s DT vessel diameter m E modulus of elasticity N/ rn 2 F force N Fcj friction force per fibre contact N Fc<n normal force per fibre contact N FSP fibre saturation point kg water/kg pulp T fibre flexibility N ' ^ m " 2 g acceleration due to gravity kg/m-s 2 H liquid depth in vessel m / area moment of inertia m 4 I, intensity of segregation, Equation 1.5 dimensionless k crowding factor, Equation 3.6 dimensionless k mass transfer coefficient m/s A;, & 2 , &3 reaction rate constants, Equations 1.7-1.12 s _ 1 or appropriate k, k', k", k'" constants dimensionless kc,kd,kf constants, Equation 2.6 dimensionless I fibre length m < I >i weighted fibre length by length, £ ? = 1 /• / E?=i h m < I >w weighted fibre length by weight, £?=i If/ £? = 11} m 1 segment length m L lignin concentration kg/kg pulp L rotor length m Lf floor lignin concentration kg/kg pulp L, scale of segregation, Equation 1.4 dimensionless NOMENCLATURE 154 LB length of impeller blade m m mass kg n number ni number of impeller/rotor blades or lugs n2 number of baffles nc number of fibre contacts nf number of fibres per m 2 of surface m - 2 minimum number of fibres per m 2 of surface m - 2 N rotational speed s - 1 NP power number, P/D*N3p dimensionless power number in the turbulent regime dimensionless NRe Reynolds number, D2Np//i dimensionless NWe Weber number, Dv2p/<r dimensionless P power Watts r fibre radius, radial distance m r2 coefficient of multiple determination dimensionless ra radius of active zone m rc radius of curvature m R rotor radius m s standard deviation s impeller pitch degrees s fibre stiffness N-m 2 Sh Sherwood number, kd/D dimensionless sa surface area of active zone m 2 t time s T torque N-m NOMENCLATURE 155 Ty relative yield stress, Equation 2.10 dimensionless u' fluctuating velocity component m/s v velocity m/s V volume m 3 w baffle width m WB width of impeller blade m W R V water retention value kg water/kg pulp x measured value, position Z degree of agglomeration, Equation 3.10 dimensionless G R E E K L E T T E R S S Y M B O L 0 7 r 9 0 e eovg Cm ^zone \ D E F I N I T I O N rate constant of particle lifetime, Equation 3.10 angle between fibre axis and plane shear rate maximum beam deflection aerodynamic specific surface angle power dissipation per unit volume average power dissipation per unit volume power dissipation per unit mass power dissipation in a mixing zone lateral dissipation length scale viscosity of continuous, dispersed phase apparent viscosity U N I T S s - 1 degrees - i m in 7kg degrees W / m 3 W / m 3 W / k g W / m 3 m N-s/m 2 N-s/m 2 NOMENCLATURE 156 coefficient of dynamic friction dimensionless coefficient of static friction dimensionless relative viscosity, f i B p / f i dimensionless suspension viscosity N-s/m 2 closeness of approach parameter, Equation 3.10 dimensionless P, PP density of continuous, dispersed phase kg /m 3 Pb bulk density k g / m 3 a surface tension N /m (Tf tensile strength N / m 2 T shear stress N / m 2 disruptive shear stress, Equation 3.4 N / m 2 rm mixing time constant s TR reaction time constant s Ty network yield stress N / m2 n angular speed, 2-KN s - 1 S U B S C R I P T S S Y M B O L D E F I N I T I O N / fibre fw free water 9 gas i index 'f swollen fibre T total w water Bibliography Abercrombie, D.A., " C D and D i High Intensity Mixers Reduce Bleaching Costs at Westar", C P P A Pacific Coast Spring Conference, Jasper, Alberta, (1986). 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Reeve, "Diffusion in Fibre Beds. Part 1: Fundamentals", C P P A Annual Meeting, Preprints 74A, 223-228 (1988). Ziegel, K.D. , "The Viscosity of Suspensions of Large, Nonspherical Particles in Polymer Fluids", J . Col l . Interface Sci. 34(2), 185-196 (1970). A p p e n d i x A P u l p F l u i d i z e r a n d H a a k e R V 1 2 A . l P u l p F l u i d i z e r D e s i g n The laboratory pulp fluidizer, a concentric cylinder device, was constructed to study pulp network yield stress and pulp suspension dynamic behaviour. It was designed to be as versatile as possible. For example, the easy interchange of housing and rotor components allowed the gap width and chamber volume to be readily varied. The general layout of the pulp fluidizer is shown in Figure A . l , and design drawings are are given in Figures A.2 through A.5. The major design features and capabilities of the pulp fluidizer are discussed below. The pulp fluidizer is powered by a 30 hp (22.4 kW) Emerson D C motor having a base speed of 1750 rpm and overspeed capability to 3500 rpm. The motor is equipped with a blower so that sustained low speed operation may be maintained. Speed control over the complete motor operating range is provided by a Spectrum II DC drive rated at 30 hp (22.4 kW). The D C Motor is coupled to the fluidizer shaft through a toothed drive belt. A 1:1.43 gearing ratio is used. Thus, up to 21 hp (15.7 kW) is available at the fluidizer shaft which can reach a maximum operating speed of 5000 rpm. The horsepower and maximum rotational speed of the shaft can be changed, if necessary, by the selection of an appropriate gearing ratio between the motor and shaft subject to the constraints of 171 APPENDIX A. PULP FLUIDIZER AND HAAKE RV12 172 Figure A . l : Photograph of the pulp fluidizer showing the fluidizer, motor power supply, I B M P C used for computer control, and digital display panel. the individual components described later. For example, by using a straight 1:1 gearing ratio, the full 30 hp (22.4 kW) would be available at the fluidizer shaft, although the maximum shaft speed would be limited to 3500 rpm. The torque available at the shaft for the 1:1.43 gearing ratio used in this study is given in Figure A.6. The fluidizer shaft components were selected to operate safely at speeds over 5000 rpm. The shaft is securred and supported by four self-aligning N T N UELP208-108-D l bearings. Two John Crane 1.5 inch 8B1 double seals (code XFID) in a stainless steel jacket provide a water cooled seal between the shaft and fluidizer chamber. The pressure inside the cooling jacket must be maintained approximately 140 kPa higher than the highest pressure anticipated in the chamber. This is accomplished by a gear pump used to boost line water pressure from 70-140 kPa to 410-680 kPa. A water flow rate of approximately 3 1/min provides sufficient cooling. Key features of the pulp fluidizer are the rotors attached to the fluidizer shaft, and APPENDIX A. PULP FLUIDIZER AND HAAKE RV12 173 Figure A.2: Side view of pulp fluidizer. Identified in the drawing are the (1) 30 hp (22.4 kW) D C variable speed motor, (2) toothed drive belt, (3) fluidizer shaft and (4) fluidizer chamber. Details of the fluidizer shaft are given in Figure A.5. APPENDIX A. PULP FLUIDIZER AND HAAKE RV12 174 Figure A.4: Plan view of pulp fluidizer. APPENDIX A. PULP FLUIDIZER AND HAAKE RV12 175 Figure A.5: Detail of pulp fluidizer shaft. Identified in the drawing are the (1) rotor (PF2), (2) chamber (Housing PFH1) , (3) Lexan cover plate, (4) side observation and pulp addition port, (5) temperature probe location, (6) housing backing plate, (7) water cooled shaft seal, (8) bearings, (9) torque transducer strain gauges, (10) drive pulley and (11) slip ring assembly for the torque transducer. o o , | | | | • cu o 3 1 0 CO O i l l ' 1 i 0 J000 2000 3000 4000 5000 R o t a t i o n a l Speed, R P M Figure A.6: Shaft torque vs. rotational speed for the pulp fluidizer. APPENDIX A. PULP FLUIDIZER AND HAAKE RV12 176 Figure A.7: Pulp fluidizer rotors used in yield and dynamic tests. From left to right: Rotors PF3 , P F 2 , PF1 and PF4 . the housings which form the chamber which contains the pulp suspension during a test. By using different rotor/housing combinations, the chamber volume and gap width can be readily varied. The rotors have lugs and the housings have baffles that protrude into the pulp suspension to prevent slippage at the solid/suspension interfaces. The fluidizer design allows for easy housing and rotor interchange. A housing change takes about thirty minutes and a rotor change less than five minutes. A l l wetted parts were constructed from 316 SS 1 which is resistant to many pulp bleaching chemicals. Viton '0'-rings were chosen for their superior chemical resistance, while the observation ports and covers were made from Lexan. A photograph of the rotors used in this study is given in Figure A.7. The design specifications of the different housings and rotors are given in Tables A . l and A.2. Measurements made during a dynamic test included the shaft torque, rotational 1With the exception of rotor PF1 which is made from aluminium. APPENDIX A. PULP FLUIDIZER AND HAAKE RV12 +• 01 t- U> r-z co O •fl- <* in < 0> O ea CM CD U) CD 1-co o O CD o CM CD CD 01 10 z •r- CO CO 01 CO o CD (D CM ID o • f l in O o O O LU LU LU LU t- t~ LO CO CO CO O CM 1- co O co o CM z 01 CD in in in LU 1 i 1 i 1 i i 1 i a. O b u CD i- o CN CO O O o O in a — in in o in < Z ID o •«t o 01 o in in CM in LU < 0. D CO in CD CM CM in CN CO o _ l o (C o o O o O (0 CD CO to o CM CN CN CM CO £ Z TH. CD CO o D O co r» t CM O O O in O CO CN CN CM in O O o C5 _ l E E o in in in CO 1- O (0 O O 00 O O o o Z o X CO O T- O CO o o in 1—1 a CM to z _ l •cr 2t •—< a I O O •r- O o o O 1-O O o Ol 01 01 Ol O o o O z co CD O o o O Ul _ l •« -a. oa LU O O ca O o o O o o O H* LU o O oo in CN o O o o O £ o CN CN CN CM o o o < Q a or a a. LU LU Ul LU LU N N N M z i—i *-< •—i a a o a X Q CM CM CN CN CN CM .—< 1—1 *-« O L u < CO > > > > > > _ l _ l _ l _ l £ 3 a. a o: EL CC Z o 1—1 1-< z O «-t m a. T CO CN *— 1- CO a a. a. 0. CM CO 1-O LU o. > _i _i _ l _1 LU LU LU LU a a o 2 x. X. X. a a CL a. z < (-t— z co < Z 1 -O IO CJ Z * o —«o s« * O " O E T Z O — w 0 3 CT a c c o o i-> ^ — «! •H 0. (0 w . — (0 01 0] 01 01 cr a D c — II -H co (. --- o a i-o_ a o w a c oi r 1/1 co 0) o • f •• Q . CO L, — 01 -f t- N (0 - O 0) T3 *-.C -CO 3 T3 — Cl LU C 3 CN a in *- — ra > 3 0) a: a s APPENDIX A. PULP FLUIDIZER AND HAAKE RV12 4-cs z Hi V) O Z 3 ZUIO-< tu X E cc »^ v e o O in O in tn O in < H a ^  in If) CD in CM tu tu a —J OQ t—o o trQ 1-< CN o> in in CO in , * _l O co 0) CM O CM CO 3 O CO in r- O cn » O * _1 CO CO CO CO O O O O < Ul -r- CJ s 3 X _l O CO > * D * tu E . CX O u> t~ CO CO CO O T~ •<]• •» in c~ O 0) t/1 < CO co CO CO O O O UJ X tt CS CM CO T CM CO •o-O M li- UL u. U. u_ U. u. ti-t- t/i a a. a a 0. a  a ck. o tu a 3 _l 10 10 0 £ *»-3 ti-Z lt) 01 C X ~-t- 01 O O o 0 d d £. 13 3 a _l H-Q 2 E a l/l E 3 •—• O 1- O o I CO I a) z d d a. o O *— +* tu 3 N </) _l 0 z o k—« E 0) 3 D _l a •— u_ t-I c a O o o 0 _i t—* o o 3 Ul T— 0 a. X c ti. (0 o in 0 z o: o tu a »—< t-Ul o o < CM COo < CM »-« u. • 1—1 £ \J tu 0 a. z L. t/i o 4-T3 CM O < Q> z z CM L. < i-i C3 I I 3 LO I-I a. ti. to Ul 3 to a. a. (0 _1 O tu 0) to I o < 01 c APPENDIX A. PULP FLUIDIZER AND HAAKE RV12 Table A.3: Response time of fluidizer measuring sensors. 179 Sensor Step Change Response Time (s) Rotational Speed 0-1000 rpm 0.24 1000-0 rpm 5.7 Temperature 22.6-37.0°C 11.9 Torque 0.2-16.9 N-m 0.22 speed, and fluid/suspension temperature inside the chamber. The details of the sensors used for these measurements, as well as event timing and fluidizer speed control, follow. Torque Measurement: The fluidizer shaft is instrumented for torque measurement using a strain gauge attached to the shaft. Two Micromeasurements type C E A -06-187UV-350 precision rosettes are configured as a 350 ohm full bridge with power supplied by a Quanta series Q 2 X X X X S strain gauge conditioner. The sensor was calibrated for 0-136 N-m and has an accuracy of ±0.3 N-m. However, the strain gauge bridge could be configured to operate at up to 190 N-m safely, and would survive a 270 N-m load although some zero drift would result. The response time 2 of the torque sensor is rapid as shown in Table A.3. Electrical signals from the torque transducer were transmitted from the shaft through a slip ring assembly. The brushes of this assembly were lifted during periods when data acquisition was not required to prolong slip ring life. Rpm Measurement: Shaft rotational speed is measured by a Monarch ROS-4 series ACT-1 remote optical sensor. This sensor integrates the number of shaft revo-lutions approximately 2.5 times each second and reports the average rotational speed in each time interval with an accuracy of 1 rpm over the range of 50-5000 rpm. The response time is rapid except when the shaft speed falls below 2The response time of a sensor is defined as the time taken for the measured signal to change from 10 to 90% of its steady state value following a step change. APPENDIX A. PULP FLUIDIZER AND HAAKE RV12 180 1000 rpm during deceleration (See Figure 3.5 and Table A.3). Housing Temperature Measurement: Temperature measurement of fluids/suspensions inside the fluidizer chamber was made with a 100 ohm platinum resistance bulb (RDT) . Temperatures over the range of 0-199.9°C could be measured to an ac-curacy of ±0.2°C. However, the response time of the temperature sensor is very slow as shown in Table A.3. Thus, only equilibrium temperatures were used. Programmed Speed Control: The control of shaft speed and data acquisition in both the yield and dynamic tests was accomplished using an I B M P C with a Tecmar A / D board. The software was written in I B M Basic. When compiled to run with the I B M Basic Compiler Version 1.1, the programs provided speed control and data acquisition at frequencies up to 30 Hz (which corresponds to time intervals as short as 0.04 s). Listings of these control programs are given in Appendix B. A.2 H a a k e R V 1 2 V i s c o m e t e r The yield stress of low consistency pulp suspensions was determined using a Haake RV12 Rotovisco concentric cylinder viscometer. Detailed information on the viscometer can be found in the instruction manual [Haake, 1980]. In order to measure a wide range of yield stresses a number of rotors were used. In all cases the rotors were profiled to prevent slippage between the rotor surface and the fibre network. Rotor dimensions are included in Table A . l . The housing used for all RV12 tests was baffled to prevent fibre slippage at the housing wall. The dimensions of this housing and the gap sizes that result using the various rotors are given in Table A.4. APPENDIX A. PULP FLUIDIZER AND HAAKE RV12 cs z U l 10 C J Z O Z U l O r—v < U l I E E < i - a Ui U i o _l m i-o o DC DC CS O >-• k— to O U l cc a CO Z z o C3 < z z n cs CO »-i 3 co O ui x a o CD o CO o o CM i n X > or <4-»-10 £ O) c 10 3 0 £. « <*-o a <-> o 3 L . O • H 0 L . *— a (0 s 0 01 c a ~-in 3 0 o) r r +J <u E O c o «l-TJ TJ IV ai u. L 3 3 in in (0 (0 ai A p p e n d i x B C o m p u t e r P r o g r a m s The major computer programs written and used as part of this project are listed here with brief explanation as to their function and use. Additional information may be found by referring to the program listings and the comments included with the program code. B . l P u l p F l u i d i z e r D a t a A c q u i s i t i o n C o m p u t e r P r o g r a m The computer program listed in Table B . l is designed to control the pulp fluidizer, acquire data from the torque, rpm, and temperature sensors, and record a point of in-terest observed by the operator. The program also includes sensor calibration, plotting and data output functions. The program is written in I B M Basic and was run on an IBM P C . Control of the Pulp Fluidizer was achieved using a Tecmar A / D board (Lab Master TM-40 P G L ) . The program makes use of the Tecmar board's timers, one digital to analogue converter (DACO), and three of the analogue to digital converters ( A / D 0, 1 and 2). Details of board programming and hardware may be found in the Tecmar owners manual [Tecmar Incorporated, 1981]. Briefly, to allow this program to run properly, the following hardware switches must be correctly set on the Tecmar board: 1. The board must be in the I/O mapped mode. 182 APPENDIX B. COMPUTER PROGRAMS 183 2. The base address of the board must be set to 1808 decimal. 3. External start conversions must be triggered by counter 5. 4. DACO must be set and calibrated for 0 to 10 volts D C . 5. The A / D converters must be configured for 0 to 10 volts DC unipolar inputs. When compiled to run with the I B M Basic Compiler Version 1.1 control and data acquisition can be accomplished at up to 30 Hz ( IBM P C ) or 100 Hz ( IBM AT) . Analogue to digital conversions are recorded to an accuracy of greater than ±0.01 second, while fluidizer motor control and flagging of the point of interest noted by the operator is accurate to within ±(1 /FREQ) seconds, where F R E Q is the frequency at which the data is obtained. For all tests, data was acquired at 25 Hz so that the accuracy of control is expected to be greater than ±0.04 second. B.2 P u l p F l u i d i z e r Y i e l d S t r e s s D e t e r m i n a t i o n C o m p u t e r P r o g r a m The computer program listed in Table B.2 controls the pulp fluidizer and data acqui-sition during a yield stress determination. The program, written in I B M Basic, was run on an I B M P C and makes use of the Tecmar A / D board which must be set up as specified in section B . l . T A B L E B.1: PULP F L U I D I Z E R DATA A C Q U I S I T I O N COMPUTER PROGRAM 10 REM PULP F L U I D I Z A T I O N DATA A C Q U I S I T I O N ROUTINE: F L U I D ( V 1 . 1 ) 2 0 REM ( C ) 1 9 8 5 , 1 9 8 6 , 1 9 8 7 b y C h a d P . J . B e n n i n g t o n . 30 REM L a s t M o d i f i c a t i o n 10 J u l y 1987. 4 0 REM B a s e A d d r e s s o f TECMAR B o a r d must b e s e t t o 1808D. B o a r d must b e I/O 5 0 REM mapped. T h e p r o g r a m d o e s a n a l o g u e t o d i g i t a l c o n v e r s i o n s o f c h a n n e l s 0 6 0 REM t o 2 ( 0 - 1 0 VDC) a n d d i g i t a l t o a n a l o g u e c o n v e r s i o n o f DAC 0 ( 0 - 1 0 V D C ) . 7 0 REM T h e p r o g r a m W111 r u n a t r a t e s o f u p t o 30Hz ( I B M PC) o r u p t o 100Hz 8 0 REM ( I B M A T ) when c o m p i l e d t o r u n w i t h BASRUN.EXE ( I B M B a s i c C o m p i l e r V 1 . 1 ) . 9 0 REM K e y <1> 1s s e t a s a " o n e - t i m e " f l a g t o r e c o r d a n o p e r a t o r o b s e r v e d p o i n t 100 REM o f I n t e r e s t . 110 REM V e r s i o n 1.1 i n c l u d e s e r r o r t r a p p i n g . 120 ON ERROR GOTO 4 3 1 0 130 ADDRESS=1808 140 DIM D F I L E ! ( 2 5 0 0 , 3 ) 150 S I Z E = 2 5 0 0 160 DIM C O N S T ! ( 2 , 1 ) 170 DIM V A L U E ! ( 2 ) 180 DIM V O L T ! ( 1 ) 190 DEFSNG A-H.L-Z 2 0 0 D E F I N T I-K 2 1 0 REM E n s u r e t h a t t h e v o l t a g e s i g n a l t o DACO I s z e r o b e f o r e s w i t c h i n g t h e 2 2 0 REM m o t o r o v e r t o c o m p u t e r c o n t r o l . 2 3 0 V0LT0UT=O: GOSUB 4 1 6 0 2 4 0 DEF F N R C 0 N V ( X ) = X + 6 * I N T ( X / 1 O ) 2 5 0 DEF F N C 0 N V ( X ) = X - 6 * I N T ( X / 1 6 ) 2 6 0 REM F i l e "CONST" m u s t b e p r o v i d e d o n t h e d e f a u l t d i s k d r i v e , a n d 2 7 0 REM c o n t a i n t h e c a l i b r a t i o n p a r a m e t e r s f o r t h e a n a l o g u e i n p u t s . 2 8 0 OPEN "CONST" FOR INPUT AS H\ 2 9 0 FOR 1=0 TO 2 3 0 0 I N P U T * 1 . C O N S T ( I . 0 ) , C O N S T ( 1,1) 3 1 0 NEXT I 3 2 0 CLOSE 3 3 0 C L S : L O C A T E 5, 1 3 4 0 PRINT " PULP F L U I D I Z A T I O N DATA A C Q U I S I T I O N " 3 5 0 PRINT " S e l e c t a F u n c t i o n " 3 6 0 PRINT " 3 7 0 PRINT 3 8 0 PRINT " 3 9 0 PRINT " 4 0 0 PRINT " 4 1 0 PRINT " 4 2 0 PRINT " 4 3 0 PRINT " 4 4 0 PRINT " 2 3 4 5 6 7 8 A c q u i r e D a t a " D i s p l a y C o n v e r s i o n C o n s t a n t s " C a l i b r a t e a n A/D S i g n a l " P e r f o r m A/D C h a n n e l C o n v e r s i o n " O u t p u t V o l t a g e t o DAC 0" P l o t D a t a " D i s p l a y T a b u l a t e d D a t a " S a v e D a t a t o a S p e c i f i e d D i s k F i l e " 4 5 0 PRINT " 4 6 0 4 7 0 4 8 0 4 9 0 5 0 0 5 1 0 5 2 0 5 3 0 5 4 0 5 5 0 5G0 5 7 0 5 8 0 5 9 0 6 0 0 6 1 0 6 2 0 6 3 0 6 4 0 6 5 0 6 6 0 6 7 0 6 8 0 6 9 0 7 0 0 7 1 0 7 2 0 7 3 0 7 4 0 7 5 0 7 6 0 7 7 0 7 8 0 7 9 0 8 0 0 8 1 0 8 2 0 8 3 0 8 4 0 8 5 0 8 6 0 8 7 0 8 8 0 8 9 0 9 0 0 9 1 0 9 2 0 9 3 0 9 18: INPUT " E n t e r 1 4 1 0 , 6 3 0 , 5 3 0 , 5 3 0 , E n d S e s s i o n ' O p t i o n : ", I 1 3 1 0 , 3 0 9 0 , 3 7 6 0 , 10, 1 PRINT " LOCATE 21 ON I GOTO 1 4 1 0 , 6 3 0 , 5 1 3 1 0 0 . 3 8 8 0 , 4 0 4 0 GOTO 3 3 0 REM REM R o u t i n e f o r c a l i b r a t i o n o f A/D I n p u t s REM CLS : LOCATE PRINT " PRINT " PRINT PRINT " PRINT " PRINT " LOCATE 2 2 , 1 3 : INPUT " S i g n a l t o b e c o n v e r t e d : ".CHANNEL IF (CHANNEL<0) OR (CHANNEL>2) THEN GOTO 6 0 0 I F 1=4 GOTO 1140 E L S E GOTO 7 3 0 D i s p l a y C o n v e r s i o n C o n s t a n t s 0 1 2 A n a l o g u e S i g n a l To Be C o n v e r t e d " T o r q u e " Rpm" T e m p e r a t u r e " REM C L S PRINT PRINT PRINT LOCATE LOCATE LOCATE LOCATE GOTO 3 3 0 REM REM REM C o n v e r s i o n C o n s t a n t s " 10, 1 1 , 12, 20, PRINT ' PRINT ' PRINT ' INPUT " H i t T o r q u e ( N . m ) = ' rpm = ' T e m p e r a t u r e ( C ) = 1 <RET> t o c o n t i n u e . C O N S T ( 0 CONST(1 C 0 N S T ( 2 , ANS$ .0) ,0) ,0) C 0 N S T ( O , 1 ) CONST( 1,1) C 0 N S T ( 2 , 1 ) V o l t a g e V o l t a g e V o l t a g e C a l i b r a t e R o u t i n e S e t u p c h a n n e l f o r A/D c o n v e r s i o n , d i s a b l e a u t o i n c r e m e n t i n g , e x t e r n a l s t a r t c o n v e r s i o n s a n d a l l i n t e r r u p t s . G a i n = 1 . 1812, 128 O u t p u t CHANNEL t o b e c o n v e r t e d 1813. CHANNEL OUT REM OUT C L S FOR 11=0 TO 1 INPUT " H i t <RET> To B e g i n a C o n v e r s i o n " , ANS$ REM S t a r t a c o n v e r s i o n , w a i t u n t i l b y t e 7=1, R e a d d a t a a n d c o n v e r t t o REM v o l t a g e . OUT 1 8 1 4 , 0 I F I N P ( 1 8 1 2 ) < 1 2 8 THEN GOTO 8 5 0 L O = I N P ( 1 8 1 3 ) H I = I N P ( 1 8 1 4 ) GOSUB 4 1 0 0 V 0 L T ( I 1)=X:PRINT INPUT " V a l u e o f NEXT 11 IF ( V O L T ( 0 ) - V O L T ( 1 ) ) = 0 THEN GOTO 9 3 0 E L S E INPUT " C a n n o t d i v i d e b y z e r o , do y o u w i s h " V o l t a g e m e a s u r e d ' "; V 0 L T ( I 1 ) S i g n a l : ", V A L U E ( I 1 ) GOTO 9 6 0 t o t r y a g a i n ? ( y / n ) " . A N S $ 9 4 0 I F (ANS$="Y") OR ( A N S $ = " y " ) THEN GOTO 8 0 0 9 5 0 I F (ANS$="N") OR (ANS$="n") THEN GOTO 3 3 0 E L S E GOTO 9 3 0 9 6 0 REM C o m p u t e C o n v e r s i o n C o n s t a n t s 9 7 0 B ! = ( V A L U E ( 0 ) - V A L U E ( 1 ) ) / ( V O L T ( 0 ) - V O L T ( 1 ) ) 9 8 0 A ! = V A L U E ( 0 ) - B * V O L T ( 0 ) 9 9 0 PRINT "A= " ;A,"B=";B:PRINT " " 1000 INPUT "Do y o u w i s h t o r e d o c a l i b r a t i o n ? ( y / n ) ",ANS$ 1010 I F (ANS$="Y") OR ( A N S $ = " y " ) THEN GOTO 8 0 0 1020 I F (ANS$="N") OR (ANS$="n") THEN GOTO 1030 E L S E GOTO 1000 1030 INPUT "Do y o u w i s h t o r e p l a c e c o n s t a n t s I n c o n v e r s i o n t a b l e ? ( y / n ) " 1040 I F (ANS$="Y") OR (ANS$="y") THEN GOTO 1070 1050 I F (ANS$="N") OR (ANS$="n") THEN GOTO 3 3 0 E L S E GOTO 1030 1060 REM R e p l a c e c o n s t a n t s 1n c o n v e r s i o n t a b l e 1070 OPEN "CONST" FOR OUTPUT AS #1 1080 C O N S T ( C H A N N E L , 0 ) = A : C O N S T ( C H A N N E L , 1 ) = B 1090 FOR 1=0 TO 2 1100 PRINT H 1 , USING "HHItH . HHHH " : CONST( I , 0 ) ; CONST ( I , 1 ) 1110 NEXT I 1120 CLOSE 1130 GOTO 6 3 0 1140 REM C o n t i n u o u s A/D C o n v e r s i o n o f s e l e c t e d c h a n n e l u s i n g e x i s t i n g 1150 REM C o n v e r s i o n c o n s t a n t s . 1160 C L S 1170 OUT 1812, 128 1180 OUT 1813,CHANNEL 1190 INPUT " H i t <RET> t o b e g i n a c o n v e r s i o n " , A N S $ 1200 OUT 1 8 1 4 , 0 1210 LOCATE 10,1: PRINT " 1220 LOCATE 1 2 , 1 : PRINT " 1230 I F I N P ( 1 8 1 2 ) < 1 2 8 THEN GOTO 1230 1240 L O = I N P ( 1 8 1 3 ) : H I = I N P ( 1 8 1 4 ) 1250 GOSUB 4 1 0 0 1260 V A L U E ( 0 ) = C O N S T ( C H A N N E L , 0 ) + C O N S T ( C H A N N E L , 1 ) * X 1270 LOCATE 10.1: PRINT " V o l t a g e = ",X,"VALUE= " , V A L U E ( 0 ) 1280 LOCATE 12,1: INPUT "Do y o u w i s h t o p e r f o r m a n o t h e r c o n v e r s i o n ? ( y / n ) 1290 I F (ANS$="Y") OR ( A N S $ = " y " ) THEN GOTO 1200 1300 I F (ANS$="N") OR (ANS$="n") THEN GOTO 3 3 0 E L S E GOTO 1280 1310 REM 1320 REM O u t p u t v o l t a g e t o DAC 0 c o n t r o l l i n g DC m o t o r d r i v e 1330 C L S 1340 LOCATE 10,9: PRINT "OUTPUT VOLTAGE TO MOTOR CONTROLLER" 1350 LOCATE 11,9: PRINT " " 1360 LOCATE 2 4 , 1 : PRINT " E n t e r <0> V o l t a g e t o r e t u r n t o menu. V o l t a g e 1370 LOCATE 12,5: INPUT " E n t e r v o l t a g e t o b e o u t p u t b y DACO: ", VOLTOUT 1380 GOSUB 4 160 1390 I F ( V 0 L T 0 U T = O ) GOTO 3 3 0 E L S E GOTO 1330 1400 REM 1410 REM M a i n P r o g r a m f o r D a t a A c q u i s i t i o n 1420 14 30 1440 1450 1460 1470 1480 1490 1500 1510 1520 1530 1540 1550 1560 1570 1580 1590 1600 1610 1620 1630 1640 1650 1660 1670 1680 1690 1700 1710 1720 1730 1740 1750 1760 1770 1780 1790 1800 1810 1820 1830 1840 1850 1860 1870 1880 1890 PULP F L U I D I Z A T I O N DATA A C Q U I S I T I O N " A c q u i r e D a t a R o u t i n e " REM C L S : LOCATE 5,1 PRINT " PRINT " PRINT " " PRINT LOCATE 10,5:INPUT " D u r a t i o n o f d a t a a c q u i s i t i o n ( I n s e c o n d s ) : ", TIME LOCATE 11,5:INPUT " S a m p l i n g f r e q u e n c y ( 1 / s e c o n d s ) : ", FREQ I F ( F R E 0 < . 6 5 ) OR ( F R E 0 > 1 0 0 ) THEN GOTO 1490 NUMBTEST=TIME*FREO IF NUMBTEST>SI2E THEN GOTO 1530 E L S E GOTO 1550 LOCATE 13,5:PRINT "Number o f t e s t s e x c e e d s a r r a y s i z e o f "; S I Z E GOTO 1480 REM S e t up e l a p s e d t i m e t i m e r REM D i s a r m c o u n t e r s 1,2 a n d 3 OUT 1 8 1 7 , 1 4 7 REM S e t up m a s t e r mode r e g i s t e r f o r : S c a l e r c o n t r o l = BCD d i v i s i o n ; REM e n a b l e I n c r e m e n t ; 8 b i t b u s ; FOUT o n , d i v i d e b y 1 , s o u r c e = F1 ; REM b o t h c o m p a r a t o r s d i s a b l e d ; d i s a b l e t i m e o f d a y mode. OUT 1817,23 OUT 1 8 1 6 , 0 OUT 18 16, 129 REM S e t up c o u n t e r 1 f o r : No g a t i n g REM s p e c i a l g a t e ; r e l o a d f r o m l o a d ; REM c o u n t up; a c t i v e h i g h TC p u l s e . OUT 1817,1 OUT 1816,57 OUT 1816,31 REM L o a d s t a r t i n g v a l u e i n t o l o a d r e g i s t e r o f c o u n t e r 1. OUT 1 8 1 6 , 0 OUT 1 8 1 6 , 0 REM S e t up c o u n t e r 2 f o r : no g a t i n g , c o u n t r i s i n g e d g e o f o u t p u t f r o m REM c o u n t e r 1, d i s a b l e s p e c i a l g a t e , r e l o a d f r o m l o a d , o n e w a y c o u n t , REM BCD c o u n t , c o u n t u p , a c t i v e h i g h TC p u l s e . OUT 1817,2 OUT 1816,57 OUT 1 8 1 6 , 0 REM L o a d s t a r t i n g v a l u e s i n t o l o a d r e g i s t e r o f c o u n t e r 2. OUT 1 8 1 6 , 0 OUT 1 8 1 6 , 0 REM L o a d c o u n t e r s 1 a n d 2 f r o m t h e i r r e s p e c t i v e l o a d r e g i s t e r s . OUT c o u n t f a l l i n g e d g e o f F 5 ; d i s a b l e c o u n t r e p e t i t i v e l y ; BCD c o u n t : 1817,67 REM S e t l o a d r e g i s t e r o f c o u n t e r OUT 1817,9 1 t o z e r o . OUT OUT 1 8 1 6 , 0 1 8 1 6 , 0 REM S e t l o a d r e g i s t e r o f c o u n t e r 2 t o z e r o . OUT 1 8 1 7 , 1 0 1900 OUT 1816,0 1910 OUT 1816,0 1920 REM S e t u p c o u n t e r 5 t o t r i g g e r a n a n a l o g t o d i g i t a l c o n v e r s i o n o f a 1930 REM s e l e c t e d I n p u t c h a n n e l a t a g i v e n f r e q u e n c y . 1940 REM A j u m p e r must b e p l a c e d b e t w e e n p i n s 3 a n d 4 o f 02, c o n n e c t i n g 1950 REM t h e o u t p u t o f c o u n t e r 5 t o t h e e x t e r n a l s t a r t c o n v e r s i o n i n p u t . 1960 REM S e t d a t a p o i n t e r t o c o u n t e r mode r e g i s t e r o f c o u n t e r 5. 1970 OUT 1817,5 1980 I F FREQ>6.25 THEN GOTO 2 0 6 0 1990 REM S e t u p c o u n t e r 5 f o r : No g a t i n g ; c o u n t r i s i n g e d g e o f F5 ( 1 0 0 H z ) ; 2 0 0 0 REM d i s a b l e s p e c i a l g a t e ; r e l o a d f r o m l o a d ; c o u n t r e p e t i t i v e l y ; 2 0 1 0 REM BCD c o u n t ; c o u n t down; a c t i v e h i g h TC p u l s e . 2 0 2 0 OUT 1816,49 2 0 3 0 OUT 1816,15 2 0 4 0 LOADNUMB=FNRCONV(100/FREQ-1)+1 2 0 5 0 GOTO 2 1 6 0 2 0 6 0 I F FREQ>62.5 THEN GOTO 2 1 2 0 2 0 7 0 REM S e t u p c o u n t e r 5 a s b e f o r e , e x c e p t c o u n t r i s i n g e d g e o f F 4 ( 1 0 0 0 H z ) . 2 0 8 0 OUT 1816,49 2 0 9 0 OUT 1816, 14 2 1 0 0 LOADNUMB=FNRCONV(1000/FREQ-1)+1 2 1 1 0 GOTO 2 1 6 0 2 1 2 0 REM S e t u p t i m e r 5 a s b e f o r e , e x c e p t c o u n t r i s i n g e d g e o f F 3 ( 1 0 0 0 0 H z ) . 2 1 3 0 OUT 1 8 1 6 , 4 9 2 1 4 0 OUT 1816,13 2 1 5 0 LOADNUMB=FNRCONV(10000/FREQ-1)+1 2 1 6 0 REM L o a d C o u n t e r 5 r e g i s t e r w i t h a p p r o p r i a t e number. T h e c o u n t e r w i l l 2 1 7 0 REM t h e n o p e r a t e a t FREO Hz. 2 1 8 0 OUT 1817, 13 2 1 9 0 OUT 1816,CINT(L0ADNUMB) 2 2 0 0 OUT 1816,0 2 2 1 0 REM S e t u p ramp c o n s t a n t s 2 2 2 0 T I N C R = ( 1 / F R E O ) 2 2 3 0 LOCATE 13,5: INPUT "Maximum RPM t o b e r e a c h e d i n r u n : ",RPMMAX 2 2 4 0 I F (RPMMAX<0) OR (RPMMAX>5000) GOTO 2 2 3 0 2 2 5 0 LOCATE 14,5: INPUT "T i m e t o r e a c h maximum RPM ( s e c o n d s ) : ",TTRPM 2 2 6 0 I F (TTRPM<0) GOTO 2 2 5 0 2 2 7 0 LOCATE 15,5: INPUT "T i m e a t maximum RPM ( s e c o n d s ) : ",TIMEAT 2 2 8 0 TIMEAT=TIMEAT+TTRPM 2 2 9 0 RPMMAX=RPMMAX/500 2 3 0 0 I F (TTRPM=0) THEN RC0NST=0:GOTO 2320 2 3 1 0 RCONST=RPMMAX/TTRPM 2 3 2 0 LOCATE 16,5: INPUT " T i m e t o r e t u r n t o z e r o RPM ( s e c o n d s ) : " . DECELT 2 3 3 0 I F ( D E C E L T = 0 ) THEN DC0NST=O:GOTO 2380 2 3 4 0 DCONST=RPMMAX/DECELT 2 3 5 0 REM 2 3 6 0 REM S e t <F1> t o b e u s e d a s a " o n e - s h o t " f l a g t o r e c o r d a n o p e r a t o r 2 3 7 0 REM o b s e r v e d p o i n t o f I n t e r e s t . 2 3 8 0 I F L U I D = 0 2 3 9 0 ON KEY ( 1 ) GOSUB 4 2 8 0 2 4 0 0 KEY ( 1 ) ON 2 4 1 0 D F I L E ( 0 , 3 ) = 0 ! 2 4 2 0 LOCATE 2 0 , 5 : I N P U T " H i t <RET> t o b e g i n d a t a a c q u i s i t i o n : ", ANS$ 2 4 3 0 LOCATE 2 2 , 5 : PRINT "ACQUIRING DATA" 2 4 4 0 REM A c q u i r e I n i t i a l v a l u e s f o r 0 t i m e . 2 4 5 0 FOR Y=0 TO 2 2 4 6 0 OUT 1813,Y: OUT 1814,0 2 4 7 0 IF I N P ( 1 8 1 2 ) < 1 2 8 THEN 2 4 7 0 2 4 8 0 L 0 = I N P ( 1 8 1 3 ) : H I = I N P ( 1 8 1 4 ) : G O S U B 4 1 0 0 2 4 9 0 D F I L E ( 0 . Y ) = X 2 5 0 0 NEXT Y 2 5 1 0 REM Arm c o u n t e r s 1,2 a n d 5. ( S t a r t c o u n t i n g ) 2 5 2 0 OUT 1 8 1 7 , 1 1 5 2 5 3 0 FOR 1=1 TO NUMBTEST 2 5 4 0 REM C o m p u t e o u t p u t v o l t a g e t o m o t o r c o n t r o l l e r ( 0 - 1 0 VDC) 2 5 5 0 IF ( D F I L E ( I - 1 , 3 ) < = TTRPM) THEN V 0 L T 0 U T = ( D F I L E ( I - 1,3)+TINCR ) *RC0NST 2 5 6 0 IF (VOLTOUT>RPMMAX) THEN V0LT0UT=RPMMAX 2 5 7 0 I F ( D F I L E ( I - 1 , 3 ) > = T I M E A T ) THEN V O L T O U T = R P M M A X + ( ( T I M E A T - D F I L E ( I - 1 , 3 ) ) * D C O N S T ) 2 5 8 0 IF ( V 0 L T 0 U T < O ) THEN V0LT0UT=O 2 5 9 0 GOSUB 4 1 6 0 2 6 0 0 REM W r i t e c o n t r o l b y t e t o b o a r d . E n a b l e e x t e r n a l s t a r t c o n v e r s i o n s . 2 6 1 0 OUT 1812,132 2 6 2 0 REM W r i t e c h a n n e l number t o b o a r d . 2 6 3 0 OUT 1813,0 2 6 4 0 I F I N P ( 1 8 1 2 ) < 1 2 8 THEN 2 6 4 0 2 6 5 0 L 0 = I N P ( 1 8 1 3 ) : H I = I N P ( 1 8 1 4 ) : G 0 S U B 4 1 0 0 2 6 6 0 D F I L E ( I , 0 ) = X 2 6 7 0 REM D i s a b l e e x t e r n a l s t a r t c o n v e r s i o n s f o r now. 2 6 8 0 OUT 1812,128 2 6 9 0 FOR Y=1 TO 2 2 7 0 0 OUT 1813,Y 2 7 1 0 OUT 1 8 1 4 , 0 2 7 2 0 REM W a l t u n t i l d o n e w i t h a c o n v e r s i o n . ( B i t 7 o f s t a t u s b y t e g o e s h i g h ) 2 7 3 0 IF I N P ( 1 8 1 2 ) < 1 2 8 THEN 2 7 3 0 2 7 4 0 REM R e a d 1n d a t a a n d c o n v e r t t o v o l t a g e . 2 7 5 0 L 0 = I N P ( 1 8 1 3 ) 2 7 6 0 H I = I N P ( 1 8 1 4 ) 2 7 7 0 GOSUB 4 1 0 0 2 7 8 0 D F I L E ( I , Y ) = X 2 7 9 0 NEXT Y 2 8 0 0 REM D i s p l a y v a l u e s i n c o u n t e r s 1 a n d 2 o f t h e 9 5 1 3 t i m e r . 2 8 1 0 REM S a v e c o u n t e r s 1 a n d 2 i n t h e i r r e s p e c t i v e h o l d r e g i s t e r s . 2 8 2 0 OUT ADDRESS+9,163 2 8 3 0 REM S e t d a t a p o i n t e r t o h o l d r e g i s t e r o f c o u n t e r 1 a n d r e a d i n d a t a . 2 8 4 0 OUT ADDRESS+9,17 2 8 5 0 HUNS=INP(ADDRESS+8) 2 8 6 0 S E C S = I N P ( A D 0 R E S S + 8 ) 2 8 7 0 REM C h e c k f o r r i p p l e c a r r y e r r o r . I f e r r o r I s p o s s i b l e , r e s a v e c o u n t e r 2 2 8 8 0 IF (HUNS+SECS)=0 THEN OUT ADDRESS+9.162 2 8 9 0 REM S e t d a t a p o l n t e r t o h o l d r e g i s t e r o f c o u n t e r 2 a n d r e a d i n d a t a . 2 9 0 0 OUT ADDRESS+9,18 2 9 1 0 H S E C = I N P ( A D D R E S S + 8 ) 2 9 2 0 T S E C = I N P ( A D D R E S S + 8 ) 2 9 3 0 D F I L E ( I , 3 ) = F N C 0 N V ( S E C S ) + F N C O N V ( H U N S ) / 1 0 0 2 9 4 0 D F I L E ( I , 3 ) = F N C O N V ( T S E C ) * 1 0 0 0 0 + F N C O N V ( H S E C ) * 1 0 0 + D F I L E ( I , 3 ) 2 9 5 0 IF FREQ>5 THEN GOTO 2 9 7 0 2 9 6 0 P R I N T , U S I N G "tfHHH.ItH " ; D F I L E ( I , 3 ) ; D F I L E ( I , 0 ) ; D F I L E ( I , 1 ) ; D F I L E ( I , 2 ) 2 9 7 0 NEXT I 2 9 8 0 V0LT0UT=O!: GOSUB 4 1 6 0 2 9 9 0 LOCATE 2 4 , 5 : PRINT "END OF DATA A C Q U I S I T I O N " 3 0 0 0 IF ( I F L U I D = 0 ) GOTO 3 0 2 0 3 0 1 0 LOCATE 2 4 , 5 : P R I N T " P o i n t o f i n t e r e s t n o t e d a t " . D F I L E ( I F L U I D , 3 ) ; " s e c o n d s 3 0 2 0 PRINT C H R $ ( 7 ) 3 0 3 0 FOR 1=0 TO NUMBTEST 3 0 4 0 FOR Y=0 TO 2 3 0 5 0 D F I L E d . Y )= CONST (Y ,0)+CONST( Y , 1 ) * D F I L E ( I , Y ) 3 0 6 0 NEXT Y 3 0 7 0 NEXT I 3 0 8 0 GOTO 3 3 0 3 0 9 0 REM 3 1 0 0 REM P l o t d a t a r o u t i n e 3 1 1 0 REM 3 1 2 0 SCREEN O: C L S : LOCATE 5,1 3 1 3 0 PRINT " DATA P L O T T I N G ROUTINE" 3 1 4 0 PRINT " " 3 1 5 0 LOCATE 10,5:INPUT " E n t e r r e t u r n c o d e <9> o r <RET> t o c o n t i n u e : ",ANS$ 3 1 6 0 I F (ANS$="9") GOTO 3 7 5 0 3 1 7 0 LOCATE 10.5:PRINT " 3 1 8 0 LOCATE 10,1 3 1 9 0 PRINT " 0 T o r q u e " 3 2 0 0 PRINT " 1 Rpm" 3 2 1 0 PRINT " 2 H o u s i n g T e m p e r a t u r e " 3 2 2 0 PRINT " 3 T i m e " 3 2 3 0 PRINT " " 3 2 4 0 LOCATE 2 0 , 5 : I N P U T " C h o o s e v a r i a b l e f o r X c o - o r d i n a t e : ", X 3 2 5 0 I F (X=0) OR (X=1) OR (X=2) OR (X=3) GOTO 3 2 6 0 E L S E GOTO 3 2 4 0 3 2 6 0 LOCATE 2 1 , 5 : I N P U T " C h o o s e v a r i a b l e f o r Y c o - o r d i n a t e : ", Y 3 2 7 0 I F ( Y = 0 ) OR (Y=1) OR (Y = 2) OR (Y=3) GOTO 3 2 8 0 E L S E GOTO 3 2 6 0 3 2 8 0 LOCATE 2 2 , 5 : INPUT " E n t e r <0> f o r p o i n t s o r <1> f o r J o i n e d l i n e s : " , P F L A G 3 2 9 0 I F ( P F L A G = 0 ) OR ( P F L A G = 1 ) GOTO 3 3 0 0 E L S E GOTO 3 2 8 0 3 3 0 0 REM S e t maximum v a l u e o f X a n d Y c o - o r d i n a t e s f o r s c a l i n g . 3 3 1 0 IF (X=0) THEN MAXX=50: GOTO 3350 3 3 2 0 I F (X=1) THEN MAXX=5000: GOTO 3 3 5 0 3 3 3 0 IF (X=2) THEN MAXX=100: GOTO 3 3 5 0 3 3 4 0 I F (X=3) THEN MAXX=DFILE(NUMBTEST,3) 3 3 5 0 I F (Y=0) THEN MAXY=50: GOTO 3 3 9 0 3 3 6 0 I F (Y=1) THEN MAXY=5000: GOTO 3 3 9 0 3 3 7 0 I F (Y=2) THEN MAXY=100: GOTO 3 3 9 0 3 3 8 0 I F (Y=3) THEN MAXY=DFILE(NUMBTEST,3) 3 3 9 0 REM I n p u t D a t a f o r p l o t 3 4 0 0 LOCATE 2 4 , 5 : I N P U T " T e s t ID D e s c r i p t i o n : "; F I L E S 3 4 1 0 X S I Z E = 5 0 0 : Y S I Z E = 1 5 O : 0 F F X = 1 0 0 : O F F Y = 2 0 3 4 2 0 SCREEN 2 : C L S 3 4 3 0 FOR 1=0 TO NUMBTEST 3 4 4 0 X P T = ( D F I L E ( I , X ) / M A X X ) * X S I Z E + O F F X 3 4 5 0 Y P T = ( 1 - D F I L E ( I , Y ) / M A X Y ) * Y S I Z E + O F F Y 3 4 6 0 I F PFLAG= 1 GOTO 3 4 9 0 3 4 7 0 P S E T ( X P T , Y P T ) 3 4 8 0 GOTO 3 5 1 0 3 4 9 0 I F 1=0 THEN P S E T ( X P T , Y P T ) : G O T O 3 5 1 0 3 5 0 0 L I N E - ( X P T , Y P T ) 3 5 1 0 NEXT I 3 5 2 0 REM P l o t p o i n t w h e r e o p e r a t o r o b s e r v e d p o i n t o f i n t e r e s t was n o t e d . 3 5 3 0 IF ( I F L U I D = 0 ) GOTO 3 5 8 0 3 5 4 0 XPT = ( D F I L E ( I F L U I D . X ) / M A X X ) * X S I Z E + O F F X 3 5 5 0 Y P T = ( 1 - D F I L E ( I F L U I D , Y ) / M A X Y ) * Y S I Z E + O F F Y 3 5 6 0 C I R C L E ( X P T , Y P T ) , 5 3 5 7 0 REM C o m p l e t e P l o t 3 5 8 0 L 1 N E ( 0 F F X , 0 F F Y ) - ( 0 F F X + X S I Z E , 0 F F Y + Y S I Z E ) , , B 3 5 9 0 LOCATE 1,1.3: PRINT " T e s t ID: " ; F I L E S 3 6 0 0 LOCATE 1.66-.PRINT DATES 3 6 1 0 LOCATE 4.3:PRINT MAXY 3 6 2 0 LOCATE 2 2 , 3 : P R I N T "0.0" 3 6 3 0 LOCATE 2 3 , 1 2 : P R I N T "0.0" 3 6 4 0 LOCATE 2 3 , 7 2 : P R I N T MAXX 3 6 5 0 ON (Y+1) GOTO 3 6 6 0 , 3 6 7 0 , 3 6 8 0 , 3 6 9 0 3 6 6 0 LOCATE 11,1:PRINT " T o r q u e , N.m":GOTO 3 7 0 0 3 6 7 0 LOCATE 11,3:PRINT "Rpm, m1n-1":G0T0 3 7 0 0 3 6 8 0 LOCATE 11,3:PRINT "Temp, C":G0T0 3 7 0 0 3 6 9 0 LOCATE 11,3:PRINT " T i m e , s e c " : G 0 T 0 3 7 0 0 3 7 0 0 ON (X+1) GOTO 3 7 1 0 , 3 7 2 0 , 3 7 3 0 , 3 7 4 0 3 7 1 0 LOCATE 2 4 , 4 0 : I N P U T " T o r q u e , N.m",ANSS:GOTO 3 1 2 0 3 7 2 0 LOCATE 2 4 , 4 0 : I N P U T "Rpm, min-1",ANSS:GOTO 3 1 2 0 3 7 3 0 LOCATE 2 4 , 4 0 : I N P U T "Temp, C",ANS$:GOTO 3 1 2 0 3 7 4 0 LOCATE 2 4 , 4 0 : I N P U T " T i m e , s e c " ,ANSS:GOTO 3 1 2 0 3 7 5 0 SCREEN 0:GOTO 320 3 7 6 0 REM 3 7 7 0 REM D i s p l a y d a t a r o u t i n e 3 7 8 0 REM 3 7 9 0 C L S 3 8 0 0 PRINT " P o i n t o f i n t e r e s t n o t e d a t "; D F I L E ( I F L U I D , 3 ) ; " s e c o n d s " 3 8 1 0 FOR 1=0 TO NUMBTEST 3 8 2 0 P R I N T , U S I N G " ft*» H . » H " ; DF I LE ( I , 3 ) ; 3 8 3 0 P R I N T , U S I N G "ttHHit.tt " ; D F I L E ( I , 0 ) ; D F I L E ( I , 1 ) ; D F I L E ( I , 2 ) 3 8 4 0 NEXT I 3 8 5 0 INPUT " H i t <RET> t o c o n t i n u e : " , ANS$ 3 8 6 0 GOTO 3 3 0 3 8 7 0 REM 3 8 8 0 REM S a v e s t e s t d a t a t o a s p e c i f i e d d i s k f i l e . 3 8 9 0 REM 3 9 0 0 C L S : L O C A T E 5.1 3 9 1 0 PRINT " SAVE DATA ON D I S K " 3 9 2 0 PRINT " " 39 3 0 PRINT 3 9 4 0 LOCATE 10,5:PRINT "Remember t o s p e c i f y d i s k d r i v e a n d f i l e e x t e n s i o n " 3 9 5 0 LOCATE 1 1 , 5 : I N P U T "Name o f f i l e t o b e s a v e d : " . F I L E S 3 9 6 0 OPEN F I L E S FOR OUTPUT AS H1 3 9 7 0 PRINT #1. U S I N G " H H H tt. H H " ; D F I L E ( I F L U I D , 3 ) 3 9 8 0 FOR 1=0 TO NUMBTEST 3 9 9 0 PRINT ti 1 , U S I N G "HttHH.ttH " ; DF I LE ( I , 3 ) ; 4 0 0 0 PRINT tt1,USING "tltttltt.lt " ; D F I L E ( I , 0 ) : D F I L E ( I , 1 ) ; D F I L E ( I , 2 ) 4 0 1 0 NEXT I 4 0 2 0 CLOSE 4 0 3 0 GOTO 3 3 0 4 0 4 0 END 4 0 5 0 REM * * * * SUBROUTINES * * * * 4 0 6 0 REM *** SUB 1 ** * 4 0 7 0 REM S u b r o u t i n e t o c o n v e r t A/D s i g n a l s r e a d t o v o l t a g e . 4 0 8 0 REM C o n v e r s i o n s e t f o r 0-10 v o l t u n i p o l a r s i g n a l w i t h t h e o u t p u t i n b i n a r y . 3 6 0 6 REM T h e a p p r o p r i a t e h a r d w a r e c h a n g e m u s t b e made o n t h e TECMAR d a u g h t e r 4 0 9 0 REM b o a r d . 4 1 0 0 X = ( 2 5 6 * H I + L 0 ) 4 1 1 0 X=X/409.5 4 1 2 0 RETURN 4 1 3 0 REM *** SUB 2 ** * 4 1 4 0 REM S u b r o u t i n e t o o u t p u t 0-10 VDC s i g n a l t o m o t o r c o n t r o l l e r . TECMAR 4 1 5 0 REM m o t h e r b o a r d DAC O must b e s e t t o 0-10 v o l t r a n g e . 4 1 6 0 D E C I M A L = 4 0 9 . 5 * V 0 L T 0 U T - 2 0 4 8 4 1 7 0 D E C I M A L 3 I N T ( D E C I M A L ) 4 180 H I G H = I N T ( D E C I M A L / 2 5 6 ) : L0W=DECIMAL-256*HIGH 4 1 9 0 I F HIGH<0 THEN HIGH=16+HIGH 4 2 0 0 REM O u t p u t v o l t a g e t o D/A 4 2 1 0 OUT ADDRESS+1, HIGH 4 2 2 0 OUT ADDRESS, LOW 4 2 3 0 RETURN 4 2 4 0 REM *** SUB 3 ** * 4 2 5 0 REM S u b r o u t i n e t o f l a g a n o p e r a t o r o b s e r v e d p o i n t o f i n t e r e s t . 4 2 6 0 REM When t h e o p e r a t o r p r e s s e s t h e <F1> k e y , t h e i t e r a t i o n number i s n o t e d 4 2 7 0 REM a n d l a t e r u s e d t o l o c a t e t h e t i m e i t was p r e s s e d t h r o u g h t h e d a t a f i l e . 4 2 8 0 I F L U I D = I 4 2 9 0 KEY ( 1 ) OFF 4 3 0 0 RETURN 4 3 1 0 REN I *** ERROR TRAPPING ROUTINE * * * * 4 3 2 0 I F ERR = 64 THEN PRINT "Bad F i l e Name" 4 3 3 0 I F ERR = 52 THEN PRINT "Bad F i l e Number" 4 3 4 0 I F ERR = 25 THEN PRINT " D e v i c e F a u l t " 4 3 5 0 I F ERR = 61 THEN PRINT " D i s k F u l 1 " 4 3 6 0 I F ERR = 72 THEN PRINT " D i s k M e d i a E r r o r " 4 3 7 0 I F ERR = 71 THEN PRINT " D i s k N o t R e a d y " 4 3 8 0 I F ERR = 7 0 THEN PRINT " D i s k W r i t e P r o t e c t " 4 3 9 0 I F ERR = 1 1 THEN PRINT " D i v i s i o n b y Z e r o " 4 4 0 0 I F ERR = 58 THEN PRINT " F i l e A l r e a d y E x i s t s 4 4 1 0 I F ERR = 27 THEN PRINT "Out o f P a p e r " 4 4 2 0 I F ERR = 2 THEN PRINT " S y n t a x E r r o r " 4 4 3 0 I F ERR = 67 THEN PRINT "Too Many F1 l e s " 4 4 4 0 INPUT " H i t <RET> t o c o n t i n u e : " , ANS$ 4 4 5 0 RESUME 3 3 0 T A B L E B.2 PULP F L U I D I Z E R Y I E L D S T R E S S DETERMINATION COMPUTER PROGRAM 10 REM PULP S U S P E N S I O N Y I E L D S T R E S S DATA A C Q U I S I T I O N : Y I E L D ( V 1 . 0 ) CT 2 0 REM ( C ) 1 9 8 6 , 1 9 8 7 b y C h a d P . J . B e n n i n g t o n . 3 0 REM L a s t M o d i f i c a t i o n 25 F e b r u a r y 1987. 4 0 REM B a s e A d d r e s s o f TECMAR B o a r d m u s t b e s e t t o 1808D. B o a r d m u s t b e I/O 5 0 REM mapped. T h e p r o g r a m d o e s a n a l o g u e t o d i g i t a l c o n v e r s i o n s o f c h a n n e l 0 6 0 REM ( t o r q u e m e a s u r e m e n t ) a n d d i g i t a l t o a n a l o g u e c o n v e r s i o n o f DACO g i v i n g 70 REM a m o t o r ramp r a t e o f 0.01 v o l t s / s e c . T h e i n t e r n a l t i m e r i s s e t t o 8 0 REM a c q u i r e d a t a a t 25 Hz when r u n w i t h BASRUN.EXE ( I B M B a s i c C o m p i l e r V 1 . 1 9 0 REM K e y <1> s t o p s t h e m o t o r ramp a n d t h e t e s t . 100 ADDRESS=1808 110 DIM D F I L E ! ( 2 0 0 0 ) 120 DEFSNG A-H.L-Z 130 D E F I N T I-K 140 REM E n s u r e t h a t t h e v o l t a g e s i g n a l t o DACO 1s z e r o b e f o r e s w i t c h i n g t h e 150 REM m o t o r o v e r t o c o m p u t e r c o n t r o l . 160 V0LT0UT=O: GOSUB 1440 170 DEF F N R C 0 N V ( X ) = X + 6 * I N T ( X / 1 0 ) 180 C L S : L 0 C A T E 5,1 190 PRINT » PULP Y I E L D S T R E S S DATA A C Q U I S I T I O N " 2 0 0 PRINT " S e l e c t a F u n c t i o n " 2 1 0 PRINT " " 2 2 0 PRINT 2 3 0 PRINT " 1 A c q u i r e D a t a " 2 4 0 PRINT " 2 P l o t D a t a " 2 5 0 PRINT " 3 D i s p l a y D a t a o n S c r e e n " 2 6 0 PRINT " 4 P r i n t D a t a o n LPT 1" 2 7 0 PRINT " 9 E n d S e s s i o n " 2 8 0 LOCATE 2 1 , 1 8 : INPUT " E n t e r O p t i o n : ", I 2 9 0 ON I GOTO 3 4 0 , 8 7 0 , 1 2 1 0 , 1 2 7 0 , 1 8 0 . 1 8 0 . 1 8 0 . 1 8 0 , 1 3 2 0 3 0 0 GOTO 180 3 1 0 REM 3 2 0 REM M a i n P r o g r a m f o r D a t a A c q u i s i t i o n 3 3 0 REM 3 4 0 C L S : LOCATE 5.1 3 5 0 P R I N T " PULP Y I E L D S T R E S S DATA A C Q U I S I T I O N " 3 6 0 PRINT " A c q u i r e D a t a R o u t i n e " 3 7 0 P R I N T " " 3 8 0 PRINT 3 9 0 REM S e t u p m a s t e r mode r e g i s t e r f o r : S c a l e r c o n t r o l = BCD d i v i s i o n ; 4 0 0 REM e n a b l e i n c r e m e n t ; 8 b i t b u s ; FOUT o n , d i v i d e b y 1 , s o u r c e = F 1 ; 4 1 0 REM b o t h c o m p a r a t o r s d i s a b l e d ; d i s a b l e t i m e o f d a y mode. 4 2 0 OUT 1 8 1 7 , 2 3 4 3 0 OUT 1 8 1 6 , 0 4 4 0 OUT 1 8 1 6 , 1 2 9 4 5 0 REM S e t u p c o u n t e r 5 t o t r i g g e r a n a n a l o g t o d i g i t a l c o n v e r s i o n o f a 4 6 0 REM s e l e c t e d i n p u t c h a n n e l a t a g i v e n f r e q u e n c y . 4 7 0 REM A j u m p e r m u s t b e p l a c e d b e t w e e n p i n s 3 a n d 4 o f 0 2 , c o n n e c t i n g 4 8 0 REM t h e o u t p u t o f c o u n t e r 5 t o t h e e x t e r n a l s t a r t c o n v e r s i o n i n p u t . 4 9 0 REM S e t d a t a p o i n t e r t o c o u n t e r mode r e g i s t e r o f c o u n t e r 5. 5 0 0 OUT 18 17.5 5 1 0 REM S e t u p c o u n t e r 5 t o c o u n t r i s i n g e d g e o f F 4 ( 1 0 0 0 H z ) . 5 2 0 OUT 1 8 1 6 , 4 9 5 3 0 OUT 1816,14 5 4 0 LOADNUMB = F N R C O N V ( 1 0 0 0 / 2 5 - 1 ) + 1 5 5 0 REM L o a d C o u n t e r 5 r e g i s t e r w i t h a p p r o p r i a t e n u m b e r . T h e c o u n t e r w i l l 5 6 0 REM t h e n o p e r a t e a t "25" Hz. 5 7 0 OUT 1 8 1 7 , 1 3 5 8 0 OUT 1 8 1 6 . C I N T ( L 0 A D N U M B ) 5 9 0 OUT 1 8 1 6 , 0 6 0 0 REM S e t <F1> t o s t o p t h e m o t o r ramp a n d t h e t e s t . 6 1 0 ON KEY ( 1 ) GOSUB 1550 6 2 0 KEY ( 1 ) ON 6 3 0 LOCATE 2 0 . 5 : I N P U T " H i t <RET> t o b e g i n d a t a a c q u i s i t i o n : ", ANS$ 6 4 0 LOCATE 2 2 , 5 : PRINT "ACQUIRING DATA" 6 5 0 REM Arm c o u n t e r s 1,2 a n d 5. ( S t a r t c o u n t i n g ) 6 6 0 OUT 1817, 115 6 7 0 NUMB=0:V0LT0UT=O 6 8 0 REM * * * L o o p H e r e * » * 6 9 0 REM C o m p u t e o u t p u t v o l t a g e t o m o t o r c o n t r o l l e r ( 0 - 1 0 VDC) 7 0 0 VOLTOUT=NUMB*(.0004):GOSUB 1440 7 1 0 REM W r i t e c o n t r o l b y t e t o b o a r d . E n a b l e e x t e r n a l s t a r t c o n v e r s i o n s . 7 2 0 OUT 1 8 1 2 , 1 3 2 7 3 0 REM W r i t e c h a n n e l number t o b o a r d . 7 4 0 OUT 1 8 1 3 . 0 7 5 0 I F I N P ( 1 8 1 2 ) < 1 2 8 THEN 7 5 0 7 6 0 LO=INP(i 1 8 1 3 ) : H I = I N P ( 1 8 1 4 ) : G O S U B 1380 7 7 0 D F I L E ( N U M B ) = X * 1 3 . 5 5 8 1 8 * 7 8 0 NUMB=NUMB+1 7 9 0 I F NUMB>=4000 GOTO 8 2 0 8 0 0 GOTO 7 0 0 8 1 0 REM »** LOOP HERE *** 8 2 0 V 0 L T 0 U T = O I : GOSUB 1440 8 3 0 GOTO 180 8 4 0 REM 8 5 0 REM P l o t d a t a r o u t i n e 8 6 0 REM 8 7 0 SCREEN 0: C L S : LOCATE 5,1 8 8 0 PRINT " DATA P L O T T I N G ROUTINE" 8 9 0 PRINT " " 9 0 0 PRINT 9 1 0 REM S e t minimum a n d maximum v a l u e s f o r X a n d Y c o - o r d i n a t e s f o r s c a l i n g . 9 2 0 MAXY=0 9 3 0 FOR 1=0 TO NUMB 9 4 0 IF D F I L E ( I ) > M A X Y THEN M A X Y = D F I L E ( I ) 9 5 0 NEXT I 9 6 0 MAXX=NUMB 9 7 0 I F NUMB>=100 THEN MINX=NUMB-100 E L S E MINX=0 9 8 0 MINY=0 9 9 0 REM I n p u t D a t a f o r p l o t 1000 LOCATE 2 4 , 5 : I N P U T " T e s t ID D e s c r i p t i o n : "; F I L E $ 1010 REM Do P l o t 1020 X S I Z E = 5 0 0 : Y S I Z E = 1 5 0 : O F F X = 1 0 0 : O F F Y = 2 0 1030 SCREEN 2 : C L S 1040 FOR I=MINX TO NUMB 1050 X P T = ( ( I - M I N X ) / ( N U M B - M I N X ) ) * X S I Z E + O F F X 1060 Y P T = ( 1 - D F I L E ( I ) / M A X Y ) * Y S I Z E + O F F Y 1070 P S E T ( X P T , Y P T ) 1080 NEXT I 1090 REM C o m p l e t e P l o t 1100 L I N E ( O F F X , O F F Y ) - ( O F F X + X S I Z E . O F F Y + Y S I Z E ) . , B 1110 LOCATE 1,13: P R I N T " T e s t I D: " ; F I L E $ 1120 LOCATE 1,66:PRINT DATES 1130 LOCATE 4.3.-PRINT MAXY 1140 LOCATE 2 2 , 3 : P R I N T " 0 . 0 " 1150 LOCATE 2 3 , 1 2 : P R I N T MINX 1160 LOCATE 2 3 . 7 2 : P R I N T MAXX 1170 LOCATE 1 1 . 1 : P R I N T " T o r q u e , N.m" 1180 L OCATE 2 4 , 4 0 : I N P U T " I t e r a t i o n n umber",ANS$ 1190 SCREEN 0:GOTO 180 1200 REM R o u t i n e t o D i s p l a y d a t a t o T e r m i n a l S c r e e n 1210 FOR 1=0 TO NUMB 1220 PRINT I . D F I L E ( I ) 1230 NEXT I 1240 INPUT " H i t <RET> t o r e t u r n t o m a i n menu:",ANS$ 1250 GOTO 180 1260 REM R o u t i n e t o o u t p u t d a t a t o LPT1 1270 FOR 1=0 TO NUMB 1280 L P R I N T I . D F I L E ( I ) 1290 NEXT I 1300 GOTO 180 1310 SCREEN 0:G0T0 180 1320 END 1330 REM * * * * SUBROUTINES * * * * 1340 REM * » * SUB 1 * * * 1350 REM S u b r o u t i n e t o c o n v e r t A/D s i g n a l s r e a d t o v o l t a g e . 1360 REM C o n v e r s i o n s e t f o r 0-10 v o l t u n i p o l a r s i g n a l w i t h t h e o u t p u t I n 1365 REM w i t h t h e a p p r o p r i a t e h a r d w a r e c h a n g e made o n t h e TECMAR d a u g h t e r 1370 REM b o a r d . 1380 X = ( 2 5 6 * H I + L 0 ) 1390 X=X/409.5 1400 RETURN 14 10 REM * * * SUB 2 * » * 1420 REM S u b r o u t i n e t o o u t p u t 0-10 VDC s i g n a l t o m o t o r c o n t r o l l e r . TECMAR 1430 REM m o t h e r b o a r d DAC O m u s t b e s e t t o 0 - 1 0 v o l t r a n g e . 1440 D E C I M A L = 4 0 9 . 5 * V 0 L T 0 U T - 2 0 4 8 1450 D E C I M A L = I N T ( D E C I M A L ) 1460 H I G H = I N T ( D E C I M A L / 2 5 6 ) : L0W=DECIMAL-256*HIGH 1470 I F HIGH<0 THEN HIGH=16+HIGH 1480 REM O u t p u t v o l t a g e t o D/A 1490 OUT ADDRESS+1, HIGH 1500 OUT ADDRESS, LOW 1510 RETURN 1520 REM * * * SUB 3 * * * 1530 REM S u b r o u t i n e t o s t o p m o t o r ramp a n d t e s t when t h e o p e r a t o r p r e s s e s 1540 REM <F1> k e y . 1550 GOTO 8 2 0 1560 KEY ( 1 ) OFF 1570 RETURN A p p e n d i x C F i b r e a n d S u s p e n s i o n P r o p e r t i e s C . l A s p e c t R a t i o The fibre aspect ratio, A, is given by l/d where I is the average fibre length and d is the average fibre diameter. The average fibre length chosen to represent I is the length weighted mean, < I >* [Mark, 1984] TV- l2 < l > i = ¥ ^ f ( a i ) This mean was chosen to properly represent the longer fibres of a suspension and minimize the effect of chop (tiny fibre fragments) on the measured fibre length. For pulp fibres, a weighted average fibre length is a more useful measure of fibre length than simply the arithmetic average due to the disproportionate influence that the longer fibres have on most sheet properties [Mark, 1984]. The fibre length of all fibre samples was measured. Where possible, fibre length was determined using a Kajaani FS-100 automated fibre length analyser. The mean fibre size was computed from the fibre length distribution measured by this instrument using Equation C . l . The FS-100 was used to measure all the pulp samples, and those synthetic fibres flexible enough to be processed by the instrument and having I < 7 mm. In general the mean fibre length of the pulp samples was based on approximately 10,000 individual fibres, while for the stiffer nylon fibres, 500-1500 fibres were measured. Where it was not possible to use the Kajaani FS-100, fibre length was measured 198 APPENDIX C. FIBRE AND SUSPENSION PROPERTIES 199 by projecting fibre images on a digitizing tablet and manually digitizing them. This labour intensive technique is described fully by Soszynski [1987]. Mean fibre lengths determined using this technique were based on the measurement of approximately 100 individual fibres. Fibre diameters were not measured. For pulp fibres, a representative fibre diameter was determined from the literature based upon the species of the pulp sample [Rydholrn, 1965; Scallan and Green, 1974, 1975]. The diameters of the synthetic fibres were calculated using the denier, fibre density and amount of water absorbed by the fibres. Detailed data for the fibre length measurements are given in Table C . l . A tabulation of representative pulp fibre diameters is given in Table C.2, and details of pulp fibre sources are recorded in Table C.3. Histograms showing the fibre size distributions are given in Figures C . l through C.9. C.2 E l a s t i c M o d u l u s The flexibility of pulp fibres is an important property affecting the formation and strength of fibre networks. The fibre flexibility, JF, and its inverse the fibre stiffness, 5, depend on the modulus of elasticity, E, and the area moment of inertia, / , of the fibre. r=s = Ti ( C 2 ) where / = nr4/4 for a rod with uniform circular cross-section. As the strength of a fibre network is expected to depend upon bending forces at fibre contact points, the modulus of elasticity is an important factor characterizing network strength. Several testing methods have been developed to measure fibre flexibility. These tests rely on fibre bending in the elastic regime [Seborg and Simmonds, 1941; Haugan and Young, 1970; Samuelsson, 1963, 1964; Tarn Doo and Kerekes, 1981, 1982]. However, as pulp fibres show a wide distribution of flexibility in a single sample [Steadman and Luner, 1985], many fibres must be tested to determine a useful mean value. Indeed, APPENDIX C. FIBRE AND SUSPENSION PROPERTIES 200 Tam Doo and Kerekes [1982] reported that for a typical pulp sample, roughly 80 fibres should be tested to obtain a mean having a precision of 10% at the 85% confidence level. No measurements of fibre flexibility were made for the pulp fibres used in this re-search. Instead, a representitive value for each pulp type was determined from the literature. Table C.4 lists values of pulp fibre stiffness measured by a number of in-vestigators. Tam Doo and Kerekes [1981, 1982] measured fibre stiffness for a number of British Columbia softwood pulps similar to those used in this study. These data, corrected by a factor suggested by Soszynski [1987], were used in this study. The cor-rection is required because test calibration in the Tam Doo and Kerekes tests had been made with wet nylon fibres assuming that the elastic modulus of wet nylon fibre was identical to that of dry nylon fibre. Measurements by Soszynski have shown that wet nylon can have an elastic modulus approximately half that of dry nylon. The modu-lus of elasticity for the nylon fibre was taken from Soszynski [1987], while that of the Spectra 900 fibre was obtained from Poursartip [1987]. C .3 W a t e r R e t e n t i o n V a l u e The water held by a pulp suspension falls into three categories [Ellis et ai, 1983]: 1. Water outside the cellulose fibres, 2. Water inside the fibres held by capillary forces, that is absorbed in the fibre walls and retained in the lumen, and 3. Chemically bound water. Water held inside the fibre cell walls causes fibre swelling. Measurement of the quantity of this water allows the volumetric concentration of a pulp suspension to be determined. Two testing methods are routinely used to determine the water absorbed by pulp fibres. APPENDIX C. FIBRE AND SUSPENSION PROPERTIES 201 The first of these is the fibre saturation point, FSP, determined by solute exclusion techniques. The F S P test has been described [Lindstrom, 1986] as follows: A known amount of a polymer solution of known concentration is added to an aqueous suspension of fibers. After thorough mixing, the polymer concentration in the aqueous phase is determined by refractometry or, in the case of optically-active substances such as dextrans, by polarimetry. The dilution of the polymer solution is dependent on the amount of water in the cell wall accessible to the polymer, and this permits the inaccessible water in the cell wall to be calculated. The second measure of the water inside the fibres is the water retention value (WRV), sometimes reported as the water retention ratio (WRR) . This is obtained by a centrifugal technique in which the mass concentration of a pulp sample is determined after having been centrifuged under fixed conditions. Ellis et al. [1983] demonstrated that the quantity of water removed from a pulp sample increased as the centrifugal force was increased. However, they found that when the W R R was plotted against the centrifugal force, a sharp break or knee occurred in the curve. They associated this behaviour . . . with a change in mechanism of water expulsion from the fibre mat, this change being from water expulsion from outside the fibres above the knee, to water expulsion from inside the fibres; that is, water held by capillary forces, below the knee. Soszynski [1987] concluded that the fibre moisture content measured at the knee of the water removal curve should be used to measure fibre swelling. However, the conditions under which the standard W R V test is conducted (a centrifugal force of 900 g applied for 30 minutes) are close to the conditions where the knee of the water removal curve typically occurs. Further, Scallan and Carles [1972] showed that for a wide range of pulps and fibres, the F S P and W R V yield identical results up to a value of 2.0 kg water/kg fibre. It would appear that up to this value the amount of water determined by either test can be used to represent the amount of water responsible for fibre swelling. APPENDIX C. FIBRE AND SUSPENSION PROPERTIES 202 For the pulp samples used in this research the water absorbed by the fibres was determined using the FSP test. The moisture absorbed by the nylon fibres was taken from Soszynski [1987], while that of the Spectra 900 fibres was measured by exposing fibre samples to a 98% relative humidity environment for 48 hours and determining the amount of water absorbed. Values of W R V for the fibres used in these experiments are reported in Table 2.1. A listing of W R V and F S P values reported in the literature for a wide range of pulp types is given in Table C.5. C . 4 E s t i m a t i n g S u s p e n s i o n V o l u m e C o n c e n t r a t i o n Pulp suspensions are usually characterized by their mass concentration or consistency, Cm- However, suspension behaviour is generally governed by the volume occupied by the fibres. The volume concentration of a suspension, C„, can be estimated knowing Cm and the amount of water absorbed by the fibres. The latter is determined using the water retention value. The mass concentration is simply the mass of dry fibre divided by the total mass of the suspension: Cm = 7 (C.3) mf + mw It is commonly determined by oven drying a pulp sample, and standard procedures are specified for this test by the C P P A and T A P P I 1 . Rearrangement of equation C.3 results in an identity useful for simplifying other expressions ' 1 - C „ m,u = ( c m)m/ ^c'4^ To calculate Cv we must determine the volume of the swollen pulp fibres, V'„/, and the ^or standard test procedures see CPPA D.16 or TAPPI T240 om-81. APPENDIX C. FIBRE AND SUSPENSION PROPERTIES 203 volume of the free water Vfv /m ' Pw Cv is given by V . / = f e + W R V ^ (C.5) \Pt P*> I ^ = ( ( ^ ) ^ - W R V ^ ) (C.6) \ \ Cm / Ow Pw I C v - vtf + vffw + vg ( c - 7 ) For pulp suspensions with Cm < 4-6% the gas phase is usually negligible. Hence vtf + vfw which simplifies to PS + W R V ( £ ) (C.8) 1 + W R V ( ^ ) When gas is present in the suspension we need to determine Vg in order to calculate Cv. The bulk density of a suspension, pb, gives us a means of determining Vg: mT mf + m w + mg P B = 1 ¥ = vf + vw + v, ( c u o ) and as mg <C (mw -f- m^) ( C . l l ) P/ V Cm / Piu ^ J giving (c,2) Substituting equation C.12 into equation C.7 gives ' A. _|_ WRV Pf Pw . » + ( ^ ) / X = I * (C13) which upon further simplification gives 1 W R V \ Cv = Cm[— + P b (C.14) VP/ Pw J APPENDIX C. FIBRE AND SUSPENSION PROPERTIES 204 Thus for suspensions where a substantial gas phase exists, measurement of Cm and Pb combined with a knowledge of the water retention value allows estimation of Cv. Similar algebraic equations may be solved to estimate Cv for suspensions where the suspending medium density differs from that of water. TABLE C,1: DIMENSIONS OF PULP AND MAN-MADE FIBRES FIBRE I D E N T I F I C A T I O N FIBRE LENGTH (mm) NUMBER o f FIBRES MEASURED LENGTH TEST METHOD FI B R E DIAMETER (mm) ASPECT RATIO <L>L AVG/D MEAN S.DEV <L>L AVG <L>W AVG NYLON, 1 mm 15 D e n i e r 1 .09 0.38 1 .22 1 .28 1528 Kajaam 0.0449 27.2 NYLON, 2 mm 15 D e n i e r 1 .79 0.42 1 .89 1 .92 1560 K a j a a m 0.0449 42. 1 NYLON, 3 mm 15 D e n i e r 3.21 0.89 3.45 3.48 1645 K a j a a m 0.0449 76.8 NYLON, 5 mm 15 D e n i e r 4.07 2. 10 5.-16 5.35 517 K a j a a m 0.0449 1 15 NYLON, 7 mm 15 D e n i e r 7.11 0.30 7. 12 7. 13 97 C o u n t 0.0449 159 SBK- 1 1 .00 1 . 17 2.37 3. 19 3157 K a j a a n i 0.03 7 9 . 0 SBK-2 1 .26 1 .26 2.51 3.28 15031 K a j a a n i 0.03 83.7 SBK-3 1 .01 1 . 19 2.40 3 .29 10039 K a j aan1 0.03 8 0 . 0 SBK-4 0.74 0.94 1 .94 2.87 10174 K a j a a m 0.03 64.7 SGW-1 0. 32 0.31 0.61 1 .09 10083 K a j a a n i 0.03 20.3 SGW-2 0.32 0.31 0.61 1 .08 10053 K a j a a m 0.03 20.3 SPECTRA 900, 3.3 mm 3. 15 0.77 3.34 3.42 195 C o u n t 0.038 87.9 SPECTRA 900, 6.2 mm 6.05 0.78 6. 15 6.20 152 C o u n t 0.038 162 TMP - 1 0.51 0. 58 1 . 16 1 .90 10083 K a j a a n i 0.03 38.7 UBK- 1 0.67 0.92 1 .93 2 .94 5058 K a j a a n i 0.03 64.3 MEAN = Number o r a r i t h m e t i c a v e r a g e <L>L = W e i g h t e d a v e r a g e f i b r e l e n g t h b y l e n g t h <L>W = W e i g h t e d a v e r a g e f i b r e l e n g t h b y w e i g h t TABLE C.2: T Y P I C A L PULP FIBRE DIMENSIONS INVESTIGATOR/REFERENCE FIBRE S P E C I E S COMMON FIBRE NAME FIBRE LENGTH (mm) FIBRE WIDTH ( „ m ) S c a l l a n a n d G r e e n [ 1 9 7 4 ] W h i t e S p r u c e W h i t e S p r u c e ( e a r l y w o o d ) S i t k a S p r u c e B a l s a m F i r W e s t e r n H e m l o c k D o u g l a s F 1 r 27 30 35 28 33 25 - 36 R h y d h o l m [ 1965] P i c e a a b l e s P i c e a a b l e s P i n u s t a e d a P s e u d o t s u g a l a t l f o H a P s e u d o t s u g a t a x l f o l l a T s u g a h e t e r o p h y l l a S c a n d a n a v i a n S p r u c e S c a n d a n a v l a n S p r u c e L o b l o l l y P i n e D o u g l a s F 1 r D o u g l a s F i r W e s t e r n H e m l o c k 3.5 3.5 4.0 3.4 3.00 - 6.00 4.0 24 - 59 27 43 37 44 41 TABLE C.3: I D E N T I F I C A T I O N AND SOURCE OF PULP FIBRES PULP I D E N T I F I C A T I O N AND SOURCE DATE AND TIME SAMPLE WAS AOUIRED AVERAGE FIBRE LENGTH <L>L (mm) COMMENTS SBK-1 : POWELL RIVER A p r i l 17, 1986 2.37 CEHH P u l p s a m p l e t a k e n f r o m Washer 55 8 5 % Hembal 15% D o u g l a s F i r SBK-2: PORT MELLON J a n . 13, 1987 11:15 - 11:45 am 2.51 Sem1-B1eached K r a f t , C ( D ) E ( 0 ) D 79 E l r e p h o B M g h t n e s s s Sample t a k e n f r o m p u l p m a c h i n e c o u c h t r i m 7 5 % Hembal 2 5 % S p r u c e SBK-3: POWELL RIVER J a n . 14, 1987 2:OO - 3:OO pm 2 . 40 CEHH P u l p s a m p l e t a k e n f r o m Washer 55 73 B r i g h t n e s s 7 5 % Hembal 2 5 % D o u g l a s F i r SBK-4: PORT MELLON J u l y 13, 1987 1:OO - 2:OO pm 1 .94 S e m i - B l e a c h e d K r a f t , C ( D ) E ( 0 ) D E D 76 E l r e p h o B r i g h t n e s s Sample t a k e n f r o m p u l p m a c h i n e c o u c h t r i m 9 3 % Hembal 7% S p r u c e SGW-1: POWELL RIVER A p r i l 17, 1986 0.61 P u l p s a m p l e t a k e n f r o m S i l v e r P r e s s 9 0 % Hembal 10% S p r u c e SGW-2: POWELL RIVER J a n . 14, 1987 11:15 - 11:45 am 0.61 P u l p s a m p l e t a k e n f r o m S i l v e r P r e s s 9 0 % Hembal 10% S p r u c e TMP- 1: POWELL RIVER J a n . 14, 1987 10:00 - 11:00 am 1 . 16 Sample t a k e n o f f d e c k e r 100% Hembal UBK-1: POWELL RIVER A p r i l 17, 1986 1 .93 P u l p s a m p l e t a k e n f r o m u n b l e a c h e d d e c k e r K a p p a No. » 36.7 8 5 % Hembal 15% D o u g l a s F i r APPENDIX C. FIBRE AND SUSPENSION PROPERTIES 208 Population Distribution 0.0 2.0 4.0 6.0 F i b r e L e n g t h , m m Length Weighted Distribution 0.0 2.0 4.0 F i b r e L e n g t h , m m 6.0 Figure C . l : Fibre length distributions of semi-bleached kraft pulp (SBK-1). 3157 fibres were measured with the Kajanni FS-100. Arithmetic mean = 1.00 mm, length weighted mean = 2.37 mm. APPENDIX C. FIBRE AND SUSPENSION PROPERTIES 209 Population Distribution 0.0 1.0 2.0 3.0 4.0 F i b r e L e n g t h , m m Length Weighted Distribution CM F i b r e L e n g t h , m m Figure C.2: Fibre length distributions of stone groundwood pulp (SGW-1). 10083 were fibres measured with the Kajanni FS-100. Arithmetic mean = 0.32 mm, length weighted mean = 0.61 mm. APPENDIX C. FIBRE AND SUSPENSION PROPERTIES 210 Population Distribution d • Fibre Length, mm Length Weighted Distribution CM O • o 0.0 1.0 2.0 3.0 4.0 Fibre Length, mm Figure C.3: Fibre length distributions of therraomechanical pulp (TMP-1) . 10083 fibres were measured with the Kajanni FS-100. Arithmetic mean = 0.51 mm, length weighted mean — 1.16 mm. APPENDIX C. FIBRE AND SUSPENSION PROPERTIES 211 Population Distribution • F H CM CO 0.0 1.0 2.0 3.0 4.0 F i b r e L e n g t h , m m Length Weighted Distribution -•-} CM • — i — 1 — 1 — ~ 0.0 1.0 2.0 3.0 4.0 F i b r e L e n g t h , m m Figure C.4: Fibre length distributions of 2 mm nylon fibres. 1560 fibres were measured with the Kajanni FS-100. Arithmetic mean = 1.79 mm, length weighted mean = 1.89 mm. APPENDIX C FIBRE AND SUSPENSION PROPERTIES 212 Population Distribution d • F i b r e L e n g t h , m m Length Weighted Distribution O I F i b r e L e n g t h , m m Figure C.5: Fibre length distributions of 3 mm nylon fibres. 1645 fibres were measured with the Kajanni FS-100. Arithmetic mean = 3.21 mm, length weighted mean = 3.45 mm. APPENDIX C. FIBRE AND SUSPENSION PROPERTIES 213 Population Distribution CM O I I ' 1 1 1 1 1 ' 1 1 ' ' 1 0.0 2.0 4.0 6.0 F i b r e L e n g t h , m m Length Weighted Distribution CM d F i b r e L e n g t h , m m Figure C.6: Fibre length distributions of 5 mm nylon fibres. 517 fibres were measured with the Kajanni FS-100. Arithmetic mean = 4.07 mm, length weighted mean = 5.16 mm. APPENDIX C. FIBRE AND SUSPENSION PROPERTIES 214 00 to d O o <=> CVJ d o d. Population Distribution 0.0 2.0 4.0 6.0 8.0 10.0 F i b r e L e n g t h , m m Length Weighted Distribution i i i i i i i i i i i 0.0 2.0 4.0 6.0 8.0 10.0 F i b r e L e n g t h , m m Figure C.7: Fibre length distributions of 7 mm nylon fibres. 97 fibres were measured with the digitizer. Arithmetic mean = 7.11 mm, length weighted mean = 7.12 mm. APPENDIX C. FIBRE AND SUSPENSION PROPERTIES 215 Population Distribution o I 5.0 F i b r e L e n g t h , m m Length Weighted Distribution d I F i b r e L e n g t h , m m Figure C.8: Fibre length distributions of 3.3 mm Spectra 900 fibres. 195 fibres were measured with the digitizer. Arithmetic mean = 3.15 mm, length weighted mean = 3.34 mm. APPENDIX C. FIBRE AND SUSPENSION PROPERTIES 216 0.0 Population Distribution 2.0 4.0 6.0 8.0 F i b r e L e n g t h , m m 10.0 Length Weighted Distribution 0.0 2.0 4.0 6.0 8.0 10.0 F i b r e L e n g t h , m m Figure C.9: Fibre length distributions of 6.2 mm Spectra 900 fibres. 152 fibres were measured with the digitizer. Arithmetic mean = 6.05 mm, length weighted mean = 6.15 mm. TABLE C.4: S T I F F N E S S OF PULP AND MAN-MADE FIBRES § p CO s O ft o S3 I n v e s t i g a t o r / R e f e r e n c e P u l p / F i b r e T y p e F i b r e S t i f f n e s s N.m**2 x 10**12 Comments S a m u e l s s o n S p r u c e s u l f i t e : ( 1 ) F i b r e f i x e d a s a c a n t i l e v e r i n a c h a n n e l [ 1 9 6 3 ] summerwood ( K a p p a 34) 8.0 + 0.5 w i t h l o a d i n g by a l a m i n a r f l o w o f w a t e r . l a t e w o o d ( K a p p a 43) 7.0 + 0.5 ( 2 ) B a r c h a r t s show r a n g e o f f i b r e s t i f f n e s s i n p u l p s a m p l e s . A p p r o x i m a t e l y 300 f i b r e s a r e r e q u i r e d t o o b t a i n a n a c c u r a t e mean. ( 3 ) F i b r e s l o n g e r t h a n 1.5mm w ere m e a s u r e d . S a m u e l s s o n S p r u c e p u l p s : C o m p a r i s o n o f wet, u n b e a t e n s u l f i t e a n d s u l f a t e [ 1 9 6 4 ] S u l f a t e e a r l y w o o d 3.9 - 4.9 l a b p r e p a r e d p u l p s u s i n g t h e m e t h o d d e s c r i b e d S u l f a t e l a t e w o o d 3.3 - 4.9 a b o v e . S u l f i t e e a r l y w o o d 1 .6 - 2.2 S u l f i t e l a t e w o o d 1 .6 2.6 H augen & Young Mg b i s u l f i t e , 5 0 % y i e l d , d = 25.7 „m ( D L o a d i n g o f f i b r e s a s s i m p l e c a n t i l e v e r s . [ 1 9 7 0 ] s e l e c t e d f i b r e s 250 + 19 ( 2 ) A l l p u l p s w e r e l a b p r e p a r e d u s i n g t h e t w i s t e d f i b r e s 58 + 53 summerwood f r o m f o u r a n n u a l g r o w t h r i n g s damaged f i b r e s 87 + 130 ( 1 0 t o 13 y e a r s ) o f a 19 y e a r o l d S u l f a t e , 5 0 . 1 % y i e l d , d = 25.9 ,,m S i t k a S p r u c e . s e l e c t e d f i b r e s 350 + 16 ( 3 ) 9 5 % C o n f i d e n c e i n t e r v a l s a r e g i v e n . t w i s t e d f i b r e s 90 + 47 NSSC. 6 9 . 8 % y i e l d , d = 28.5 „m s e l e c t e d f i b r e s 414 + 24 t w i s t e d f i b r e s 281 + 60 damaged f i b r e s 208 + 149 Tarn Doo & 15 D e n i e r N y l o n 638 + 100 ( 1 ) B e n d i n g o f t h e f i b r e a s s i m p l y s u p p o r t e d K e r e k e s W e s t e r n C a n a d a M i l l P u l p s : beam u s i n g t h e f o r c e o f w a t e r f l o w i n g [ 1981, 1982 ] TMP ( P r i m a r y d i s c h a r g e ) 157 + 160 p a s t t h e f i b r e . TMP ( S e c o n d a r y d i s c h a r g e ) 83 + 69 ( 2 ) P u l p o b t a i n e d f r o m West C o a s t M i l l s . M a i n l y SGW 71 + 132 s p r u c e . SBK 2. 7± 2 . 5 ( 3 ) S t a n d a r d d e v i a t i o n s o f t e s t r e s u l t s a r e g i v e n to h—' TABLE C.4: S T I F F N E S S OF PULP AND MAN-MADE FIBRES ( C o n t i n u e d ) I n v e s t 1 g a t o r / R e f e r e n c e P u l p / F 1 b r e T y p e F i b r e S t i f f n e s s N.m**2 x 10**12 Comments Ste a d m a n 8 L u n e r [ 1985] B l a c k S p r u c e D o u g l a s F i r TMP/CTMP 10 2.22 0.58 - 25 ( 1 ) F i b r e f l e x i b i l i t y was d e t e r m i n e d f r o m t h e ' n o - c o n t a c t ' l e n g t h o f f i b r e s a r c i n g o v e r w i r e s o f known d i a m e t e r . ( 2 ) F r e q u e n c y d i s t r i b u t i o n o f f i b r e s t i f f n e s s 1s g i v e n f o r D o u g l a s F i r . ( 3 ) C o m p a r i s o n i s made t o t h e m e t h o d o f Tam Doo & K e r e k e s . F i b r e s t i f f n e s s i s r e p o r t e d t o b e a p p r o x i m a t e l y s i x t i m e s l o w e r t h a n f o u n d by Tam Doo & K e r e k e s . S o s z y n s k i ( 1987] N y l o n 66 f i b r e s : 3 d e n i e r : d = 19.8 ^m 6 d e n i e r : d = 28.0 15 d e n i e r : d = 44.2 pm 12.6 53.3 329 ( 1 ) U s e d l o a d - e l o n g a t i o n p r o c e d u r e t o m e a s u r e s t i f f n e s s o f 3 a n d 6 d e n i e r n y l o n monomer i n t h e e l a t i c r e g i m e . ( 2 ) F o u n d t h a t t h e m o d u l u s o f e l a s t i c i t y d e t e r m i n e d u s i n g t h e Tam Doo a n d K e r e k e s m e t h o d v a r i e d w i t h f i b r e d e f l e c t i o n . As t h e e r r o r was i n t h e c o m p u t a t i o n a l p r o c e d u r e , t h e raw d a t a was k e p t b u t t h e a n a l y s i s p r o c e d u r e m o d i f i e d . ( 3 ) N o t e d t h a t a l l — d r y f i l a m e n t s e x h i b i t e d e l a s t i c modul11 a p p r o x i m a t e l y two t i m e s h i g h e r t h a n w a t e r s a t u r a t e d f i l a m e n t s . ( 4 ) F o r a l l d e n l e r s , E = 1.76E09 Pa. TABLE C.5: WATER RETENTION VALUE (WRV) AND FIBRE SATURATION POINT ( F S P ) OF PULP AND MAN-MADE FIBRES INVESTIGATOR/REFERENCE PULP/FIBRE TYPE WRV FSP ( k g / k g ) ( k g / k g ) S c a l l a n a n d C a r l e s [ 1 9 7 2 ] S p r u c e K r a f t ( u n b e a t e n ) Y i e l d : 93.4°/. 0 87 0.91 7 6 . 8 % 1 20 1 . 16 6 2 . 4 % 1 52 1.61 S p r u c e K r a f t , 6 3 . 8 % Y i e l d u n b e a t e n 1 57 1 .66 619 ml CSF 1 83 1 .77 354 ml CSF 1 87 1 .86 221 ml CSF 1 98 2. 18 S p r u c e S o d a , u n b e a t e n Y i e l d : 9 0 . 2 % 0 96 0.95 6 0 . 9 % 1 56 1 .58 K a t z e t a l . [ 1981 ] A s p e n Groundwood 0.8 E11 I s e t a l . [ 1983] B l e a c h e d S o f t w o o d K r a f t ( n e v e r d r i e d ) : 670 ml CSF ( u n b e a t e n ) 2 0 605 ml CSF 2 3 302 ml CSF 2 4 200 ml CSF 2 4 100 ml CSF 2 6 B l e a c h e d Hardwood K r a f t ( n e v e r d r i e d ) : 6 00 ml CSF ( u n b e a t e n ) 1 8 300 ml CSF 2 0 B l e a c h e d Hardwood K r a f t ( d r i e d t w i c e ) : ( u n b e a t e n ) 0 9 E n h r o o t h [ 1 9 8 4 ] A d d C h l o r i t e D e l i g n l f l e d Wood P u l p D e g r e e o f D e l I g m c a t l o n : 0 . 0 % 0 84 2 5 . 5 % 1 02 51 .0% 1 17 6 2 . 4 % 1 52 S o s z y n s k i [ 1 9 8 7 ] N y l o n F i b r e - 15 D e n i e r 0 07 6 9 T h i s Work SBK-1 1 .26 SBK-2 1 .29 SGW-1 0.84 TMP-1 0.91 S p e c t r a 900 0 01 A p p e n d i x D L i te ra tu re Searches The principal findings in the literature reviewed during this research have been sum-marized in point form in this appendix. The information has been classified into the following topics of interest: rate-determining step in pulp chlorination (Table D. l ) ; mix-ing of pidp suspensions, with emphasis on mixing in bleaching operations (Table D.2); the strength of pulp and man-made fibre suspensions (Tables D.3 to D.5); and the viscosity of fibrous suspensions (Table D.6). 220 TABLE D , 1 : LITERATURE SEARCH: CHLORINATION REACTION K I N E T I C S ft X A u t h o r s T e s t C o n d i t i o n s R e a c t i o n M o d e l a n d Comments C h a p n e r k a r t1961 ] R a p s o n & A n d e r s o n [ 1 9 6 6 ] R u s s e 1 [ 1 9 6 6 a : 1 9 6 6 b ] A q u e o u s c h l o r i n a t i o n o f k r a f t s l a s h p i n e p u l p 1n a b a t c h CSTR u n d e r c o n d i t i o n s o f f a l l i n g a n d c o n s t a n t c h l o r i n e c o n c e n t r a t i o n . P u l p mass c o n c e n t r a t i o n = 1,2 a n d 3% C h l o r i n e c o n c e n t r a t i o n = 0.36 - 1.63 g/L R e a c t i o n t e m p e r a t u r e * 77*F D y n a m i c b l e a c h i n g s t u d i e d . H e r e t h e c h e m i c a l 1s p a s s e d t h r o u g h a p a c k e d b e d o f f i b r e s . A q u e o u s c h l o r i n a t i o n o f s p r u c e p u l p m e a l s In a t u b u l a r r e a c t o r . I n i t i a l K l a s s o n 11gn1n = 9.88 - 2.53% P u l p mass c o n c e n t r a t i o n = 1.0% C h l o r i n e c o n c e n t r a t i o n = 0 . 5 2 - 1.31 g/L R e a c t i o n t e m p e r a t u r e = 8.8 - 23.3"C pH = 1.32 - 3.96 ( 1 ) Homogeneous m o d e l . ( 2 ) M o d e l l e d c h l o r i n a t i o n u s i n g two s l m u l a t n e o u s f i r s t o r d e r e q u a t i o n s . A c e r t a i n p o r t i o n o f t h e H g n i n was assummed t o be r e m o v e d i n s t a n t l y . R a t e a n d e x t e n t o f c h e m i c a l r e a c t i o n I n c r e a s e u n d e r d y n a m i c b l e a c h i n g c o n d i t i o n s . ( 1 ) Homogeneous r e a c t i o n k i n e t i c s : d L / d t = k f ( L , C ) where L » l i g n i n , C = c h l o r i n e , k = r a t e c o n s t a n t , a n d t = r e a c t i o n t i m e . ( 2 ) By u s i n g e x c e s s c h l o r i n e , c h l o r i n e c o n c e n t r a t i o n Is c o n s t a n t , a n d - d L / d t = k ' ( L ) * * a ( 3 ) F o u n d a t o be "somewhat" l e s s t h a n 2 ( u s e d 1 . 8 ) . ( 4 ) pH was h i g h e r t h a n I n d u s t r i a l p r a c t i c e (pH=2) a n d I t Is l i k e l y t h a t h y p o c h l o r o u s a d d t o o k p a r t 1n t h e r e a c t i o n . ( 5 ) k' was p r o f o u n d l y a f f e c t e d b y c h a n g e s 1n r e a c t i o n t e m p e r a t u r e . H ft 1=3 >-CJ SJ ft CO ft S3 o 3 CO K a r t e r ( 1 9 6 8 ; 1971 ] A q u e o u s c h l o r i n a t i o n o f k r a f t a n d s u l f i t e p u l p s ( L o b l o l l y P i n e ) 1n a t u b u l a r r e a c t o r . I n i t i a l K l a s s o n H g n i n = 9.62 - 2.33% C h l o r i n e c o n c e n t r a t i o n = 0.49 - 2.10 g/L R e a c t i o n t e m p e r a t u r e = 25.0 - 27.2*C S y s t e m pH = 2.05 - 2.10 ( 1 ) T h r e e d i f f e r e n t r e a c t i o n m o d e l s were p r o p o s e d : f i l m d i f f u s i o n , c h e m i c a l r e a c t i o n , a n d I n t e r n a l d i f f u s i o n c o n t r o l l i n g . ( 2 ) The i n t e r n a l d i f f u s i o n model was f o u n d t o b e s t model t h e e x p e r i m e n t a l d a t a . However, t h i s model r e l i e s o n t h e a s s u m p t i o n o f h i g h l y n o n - F 1 c k e a n d i f f u s i o n o f c h l o r i n e t h r o u g h t h e c e l l w a l l , l . e ( D / D o ) * * n , w h e r e n = 5 - 10. ( 3 ) The i n i t i a l p h a s e o f c h l o r i n a t i o n was more r a p i d t h a n h a d p r e v i o u s l y b e e n t h o u g h t , l e a d i n g K a r t e r t o s u g g e s t t h a t a d v a n t a g e s c o u l d be g a i n e d b y r a p i d c o n t a c t . I n t i m a t e m i x i n g c o n t i n u o u s r e a c t o r s . t-O to TABLE D . I : LITERATURE SEARCH ( c o n t i n u e d ) : CHLORINATION REACTION K I N E T I C S A u t h o r s T e s t C o n d i t i o n s R e a c t i o n Model Comments a n d A c k e r t [ 1 9 7 3 ] A q u e o u s c h l o r i n a t i o n o f D o u g l a s F i r (<10% H e m l o c k ) p u l p h a v i n g a K a p p a number o f 25 u s i n g a b a t c h f l o w r e a c t o r ( C S T R ) a n d a d i f f e r e n t i a l f l o w r e a c t o r ( p u l p p a d s ) . ( 1 ) E x a m i n e d a number o f homogeneous a n d h e t e r o g e n e o u s r e a c t i o n m o d e l s a n d f o u n d t h e b e s t a g g r e e m e n t w i t h e x p e r i m e n t u s i n g a m u l t i p l e r e a c t i o n homogeneous model h a v i n g f o u r p a r a m e t e r s : L + c h l o r i n e > A ( n o t r e m o v a b l e ) ; k1 L + c h l o r i n e > B ( r e m o v a b l e ) ; k2 A + c h l o r i n e > C ( r e m o v a b l e ) ; k3 ( 2 ) None o f t h e h e t e r o g e n e o u s r e a c t i o n m o d e l s d e s c r i b e d t h e e x p e r i m e n t a l d a t a a s w e l l a s a n y o f t h e homogeneous m o d e l s . TABLE 0.2: LITERATURE SEARCH: MIXING OF PULP SUSPENSIONS A u t h o r s E x p e r i m e n t a l P r o g r a m 6 / o r R e p o r t C o n t e n t R e s u l t s S Comments 0 1 d s h u e G r e t t o n [ 1956] P e r f o r m a n c e a n d d e s i g n o f p a p e r s t o c k m i x e r s b a s e d on p i l o t s c a l e s t u d i e s . ( 1 ) ' C o m p l e t e u n i f o r m i t y ' a t t a i n e d when s u f f i c i e n t power was a d d e d t o t h e s y s t e m s u c h t h a t t h e d e v i a t i o n s b e t w e e n c o n s i s t e n c y s a m p l e s t a k e n f r o m t h e t a n k d i s c h a r g e r e a c h e d a minimum w h i c h was n o t r e d u c e d u p o n f u r t h e r I n c r e a s e i n a g i t a t o r power. ( 2 ) V a r i a b l e s s t u d i e d I n c l u d e d : ( a ) i m p e l l e r t o t a n k d i a m e t e r r a t i o ( D / D ( T ) ) , ( b ) i m p e l l e r t y p e , ( c ) s t o c k c o n s i s t e n c y , ( d ) s t o c k t y p e , a n d ( e ) s c a l e - u p f a c t o r . ( 3 ) The h o r s e p o w e r r e q u i r e d t o a c h i e v e ' c o m p l e t e u n i f o r m i t y ' v s . D / D ( T ) r a t i o Is g i v e n . A g r a p h g i v e s t h e p r o c e s s power r a t i o v s . s t o c k c o n c e n t r a t i o n . P v a r i e s a s Cm**2.5. O l d s h u e & G r e t t o n [ 1958] S i d e - e n t e r i n g p r o p e l l e r m i x e r s i n v e r t i c a l c y l i n d r i c a l s t o c k c h e s t s a r e d i s c u s s e d . Power r a t i o s t o a c h i e v e ' c o m p l e t e u n i f o r m i t y ' a s a f u n c t i o n p u l p t y p e , mass c o n c e n t r a t i o n , a n d D /D(T) a r e g i v e n . 4% s u l p h i t e s t o c k 1s u s e d a s a r e f e r e n c e . A b s o l u t e v a l u e s a r e n o t g i v e n . W a l k e r S C h o l e t t e [ 1958 ] M e t h o d t o d e t e r m i n e t h e amount o f d a m p i n g p e r f o r m e d by i d e a l s t o c k c h e s t s . D e s i g n o f CST s t o c k c h e s t s f o r m a c r o s c a l e m i x i n g . See a l s o C h o l e t t e a n d C l o u t l e r [ 1 9 5 9 ] a n d R e y n o l d s , G i b b o n a n d A t t w o o d [ 1 9 6 4 ] . S h e r a [ 1 9 5 9 ] P u l p c h l o r i n a t i o n i s d i s c u s s e d . ( 1 ) S u p p l i e r P a p e r . No e x p e r i m e n t a l p r o g r a m . ( 2 ) Recommended d i s p e r s i o n o f c h l o r i n e g a s i n a w a t e r s t r e a m p r i o r t o a d d i t i o n t o t h e p u l p a n d a h e a d o f t h e m i x e r . S t a t e d t h a t s m a l l b u b b l e s i n c r e a s e d t h e d i s s o l u t i o n r a t e o f c h l o r i n e a n d become t r a p p e d among t h e f i b r e s a s o p p o s e d t o c o a l e s c i n g . ( 3 ) N o t e d t h a t f o r 12-16% Cm p u l p t h a t f i b r e s a r e " t h i r s t y " f o r l i q u i d , a n d t h a t p r e s s u r e a n d s q u e e z i n g f o r c e s a r e r e q u i r e d t o f o r c e l i q u i d f r o m f i b r e t o f i b r e . S c h l u m b e r g e r T h e b e n e f i t s due t o i m p r o v e d c h l o r i n a t i o n [ 1 9 6 1 ] a r e e v a l u a t e d . I m p r o v e m e n t s i n c l u d e d : ( a ) ORP c o n t r o l , ( b ) a d d i t i o n o f 3 H o o k e r s t a t i c m i x e r s , a n d ( c ) i m p r o v e d c h l o r i n e g a s i n j e c t i o n . ( 1 ) C h a n g e s r e s u l t e d In i m p r o v e d b l e a c h p l a n t c o n t r o l a n d i m p r o v e d p u l p u n i f o r m i t y . ( 2 ) R e p o r t s c h l o r i n e s a v i n g s o f 7.6 - 12.6 k g / t . ( 3 ) I m p r o v e d s t a n d a r d d e v i a t i o n o f CE p e r m a n g a n a t e number a n d v a r i a t i o n In h y p o c h l o r i t e a d d i t i o n . ( 4 ) I t 1s n o t p o s s i b l e t o s e p a r a t e l y q u a n t i f y t h e b e n e f i t s due t o I m p r o v e d m i x i n g . TABLE D.2: L I TERATURE SEARCH ( c o n t i n u e d ) : MIXING OF PULP SUSPENSIONS ft b I § ft 1 Co A u t h o r s E x p e r i m e n t a l P r o g r a m &/or R e p o r t C o n t e n t R e s u l t s & Comments A t t w o o d & G i b b o n [ 1963] S h e r a [ 1 9 6 3 ] F r e n c h [ 1964] A t k I n s o n 8 P a r t r i d g e [ 1966] D i s c u s s e s a g i t a t i o n / m i x i n g o f p a p e r s t o c k w i t h C S T ' s . S c a l e - u p i s d i s c u s s e d . P r o p r i e t a r y a r t i c l e " e v a l u a t e s " p u l p c h l o r i n a t i o n e q u i p m e n t . I n p a r t , i m p r o v e d m i x i n g o f p u l p a n d c h l o r i n e Is d i s c u s s e d . M i l l s c a l e e v a l u a t i o n o f c h e m i c a l s a v i n g s a f t e r t h e a d d i t i o n o f a H o o k e r s t a t i c m i x e r t o t h e e x i s t i n g c h l o r i n a t i o n s y s t e m . L a b o r a t o r y b l e a c h i n g s t u d y o f p u l p m i x i n g u s i n g a S o u t h e r n P i n e o f p e r m a n g a n a t e number 20.5. P o o r m i x i n g was s i m u l a t e d by t r e a t i n g p u l p s a m p l e s w i t h d i f f e r e n t q u a n t i t i e s o f c h e m i c a l a n d t h e n c o m b i n i n g them f o r f u r t h e r t r e a t m e n t a n d t h e a s s e s s m e n t o f p u l p p r o p e r t i e s . T h i s t e c h n i q u e f o r s i m u l a t i n g m i x i n g i n e f f i c i e n c y i s s i m i l a r t o t h a t u s e d by o t h e r I n v e s t i g a t o r s , a n d c a n be t e r m e d " c h a r g e d e v i a t i o n " . ( 1 ) E x p e r i m e n t a l l y d e t e r m i n e d m a c r o s c a l e m i x i n g u s i n g r a d l o a c t 1 v e l y t a g g e d f i b r e s . ( 2 ) Gave a s c a l e - u p c r i t e r i o n f o r p r o v i d i n g ' c o m p l e t e m o t i o n ' u s i n g p r o p e l l e r m i x e r s : P = C » ( D * * 2 . 6 ) « ( m * * 2 . 9 ) where P = power, C = m i x i n g c h e s t c o n s t a n t , D = a g i t a t o r d i a m e t e r , a n d m = k i n e m a t i c s h e a r p r o p e r t y o f t h e p u l p . A d v o c a t e s u s e o f a n a g i t a t e d r e t e n t i o n m i x e r t o e n s u r e t h a t a i l c h l o r i n e g a s 1s d i s s o l v e d p r i o r t o e n t e r i n g t h e r e t e n t i o n t o w e r . S u g g e s t e d r e t e n t i o n t i m e I s 1.5 m i n u t e s . ( 1 ) R e p o r t s c h l o r i n e s a v i n g s o f 18%, a n d a d e c r e a s e i n c h l o r i n e v a t r e s i d u a l o f 30%. ( 2 ) I m p r o v e d CE p e r m a n g a n a t e number c o n t r o l . ( 1 ) B e t t e r m i x i n g g a v e a h i g h e r b r i g h t n e s s f o r a n y g i v e n c h e m i c a l a p p l i c a t i o n f o r CEHDED a n d CEDED s e q u e n c e s . ( 2 ) F o r any g i v e n b r i g h t n e s s l e v e l a t t a i n e d , t h e p u l p s a m p l e s r e a c t e d u n d e r c o n d i t i o n s o f " g o o d " m i x i n g showed h i g h e r s t r e n g t h s ( v i s c o s i t i e s ) t h a n t h o s e r e a c t e d u n d e r " p o o r " m i x i n g c o n d i t i o n s . ( 3 ) M i x i n g g o o d n e s s was n o t q u a n t i f i e d . B a t e s . F o n d y & F e m e ( 1 9 6 6 ] C h a p t e r on ' I m p e l l e r c h a r a c t e r i s t i c s a n d power' i n M i x i n g , V o l I , e d i t e d by U h l a n d G r a y . D i s c u s s e s CST d e s i g n i n g e n e r a l . G i v e s a v a l u e o f 1 t o 2 HP/1000 USG t o mix a n d k e e p 1n m o t i o n a 4% b l e a c h e d s u l f i t e p u l p . F r e e d m a n [ 1 9 6 8 ] P r o p r i e t a r y p i t c h f o r a new c h l o r i n e / p u l p m i x e r . A d v o c a t e d u s e o f a " K i n e t i c A e r a t o r " t i m e t o 1-2 m i n u t e s . t o r e d u c e c h l o r i n a t i o n to to TABLE D.2: LITERATURE SEARCH ( c o n t i n u e d ) : MIXING OF PULP SUSPENSIONS ft A u t h o r s E x p e r i m e n t a l P r o g r a m 8 / o r R e p o r t C o n t e n t R e s u l t s 5 Comments C h e n & Wong [ 1973) E l l i o t t 6 F a r r ( 1973] K a l mm e t a l . [ 1974] G u 1 1 1 c h s e n [ 197G] I n - l i n e s t a t i c m i x e r s a r e d i s c u s s e d w i t h e m p h a s i s on power s a v i n g s o v e r d y n a m i c m 1 x e r s C o m p a r e d m i l l m i x i n g u s i n g c h e m i c a l r e s i d u a l a n d t h e o x i d a t i o n r e d u c t i o n p o t e n t i a l (ORP) b e f o r e a n d a f t e r c h a n g i n g c h l o r i n a t i o n m i x e r s i n a CEHD b l e a c h p l a n t . Power number f o r m i x i n g low c o n s i s t e n c y u n b l e a c h e d s u l f i t e p u l p was d e t e r m i n e d a s a f u n c t i o n o f Re, He, a n d F r In l a b s c a l e o p e n t u r b i n e m i x e r s . E f f o r t s t o d e v e l o p a c h l o r i n a t i o n t h a t o p e r a t e s a t 9-11% p u l p mass c o n c e n t r a t i o n 1s d i s c u s s e d . P a p e r d i s c u s s e s t h e m i x i n g o f b l e a c h i n g c h e m i c a l s I n t o 10% Cm p u l p s t o c k . p r o c e s s S u p p l i e r p a p e r . Low c o n s i s t e n c y p u l p c h l o r i n a t i o n u s i n g a n I n - l i n e s t a t i c m i x e r . A u t h o r s s t a t e t h a t " M i c r o s c a l e t u r b u l e n c e 1n t h e m i x e r b r e a k s up lumps o f p u l p f i b r e and c a u s e s I n t i m a t e m i x i n g b e t w e e n t h e f i b r e a n d c h e m i c a l s " . ( 1 ) A Wobble p l a t e m i x e r was r e p l a c e d w i t h a F 1 s c a l 1 n m i x e r a n d r e s u l t e d 1n s a v i n g s o f c h l o r i n e ( 8 . 9 k g / t ) a s w e l l as c a u s t i c ( 3 . 5 k g / t ) a n d h y p o c h l o r i t e ( 5 . 8 k g / t ) . ( 2 ) No c h l o r i n e d i o x i d e s a v i n g s were a c h i e v e d . P u l p s u s p e n s i o n r h e o l o g y d e s c r i b e d b y : T = TO + k-)r**m w i t h p a r a m e t e r s k a n d m u s e d In t h e e v a l u a t i o n o f Re. P u l p s u s p e n s i o n s become " f l u l d l z e d " when t h e y a r e e x p o s e d t o s u f f i c i e n t l y h i g h s h e a r s t r e s s a n d t h u s c a n be r e a d i l y m i x e d . Two f l u l d l z l n g m i x e r s 1n s e r i e s ( c h l o r i n e d i o x i d e s o l u t i o n a d d e d In t h e f i r s t a n d c h l o r i n e g a s a d d e d m t h e s e c o n d w ere t e s t e d 1n a p i l o t p l a n t a n d f o u n d t o g i v e g o o d r e s u l t s . t g S3 H CJ S3 o CO Swenson [197G] D i s c u s s e s t h e b e n e f i t s o f u s i n g s t a t i c m i x e r s ( 1 ) S u p p l i e r p a p e r . o n medium c o n s i s t e n c y p u l p s u s p e n s i o n s . ( 2 ) C h a n g e s In c h e m i c a l I n j e c t i o n a n d t h e u s e o f s t a t i c m i x e r ( c u t a n d t u r n t y p e ) r e s u l t e d m " g o o d p u l p u n i f o r m i t y a n d b r i g h t n e s s a t t h e e x p e c t e d l e v e l o f c h e m i c a l c o n s u m p t i o n . " ( 3 ) C i t e d e n e r g y s a v i n g s o f s t a t i c m i x e r s o v e r m e c h a n i c a l m 1 xers. L e h t o l a ft P u l p m i x i n g was a s s e s s e d u s i n g ' 4 N a as a K u o p p a m a k i r a d i o t r a c e r . [ 1978] A x i a l a n d r a d i a l m i x i n g w ere m e a s u r e d ( u s i n g s t a n d a r d d e v i a t i o n ) f o r a s t a t i c m i x e r a s a f u n c t i o n o f t h e number o f b l a d e ( s t a t o r ) I n s e r t s . to to TABLE D.2: L I TERATURE SEARCH ( c o n t i n u e d ) : MIXING OF PULP SUSPENSIONS ft g to El S3 g ft S3 1 co A u t h o r s E x p e r i m e n t a l P r o g r a m S / o r R e p o r t C o n t e n t R e s u l t s 8> Comments M a c D o n a 1 d [ 1979] K e s z t h e l y i & B a b a n i k o s [ 1 9 8 1 ] T o r r e g r o s s a [ 1983] R e p o r t s I m p r o v e d c h l o r i n a t i o n c o n t r o l f o l l o w i n g C h l o r i n a t i o n s t a g e u p g r a d e . I m p r o v e m e n t s i n c l u d e d u s e o f c o m p u t e r c o n t r o l , u s e o f a n o p t i c a l s e n s o r a n d i m p r o v e d m i x i n g . D i s c u s s a g i t a t i o n / m i x i n g o f p u l p s u s p e n s i o n s b y p r o p e l l e r m i x e r s . ( 1 ) U s e d t r a c e r s ( L i C l ) a n d t h e t e m p e r a t u r e r i s e o f r e a c t i o n t o e s t i m a t e m i x i n g g o o d n e s s f o r a number o f c h l o r i n e d i o x i d e m i x e r s . ( 2 ) B l e a c h e d p u l p i n t h e l a b o r a t o r y u s i n g a c h a r g e d e v i a t i o n m e t h o d . ( 3 ) R e p o r t s r e s u l t s o f I m p r o v e d m i x i n g where Kamyr MC m i x e r s r e p l a c e d e x i s t i n g m i l l m 1 x e r s . R e p o r t s 7 5 % r e d u c t i o n i n CEK number. T h e b e n e f i t s o f i m p r o v e d m i x i n g ( r e p l a c e m e n t o f a H o o k e r c h l o r i n e m i x e r a n d B r l n k l e y m i x e r w i t h a Komax i n - l i n e s t a t i c m i x e r ) c a n n o t be s e p e r a t e l y q u a n t i f i e d . ( 1 ) ( 2 ) ( 3 ) ( 4 ) S u p p l 1 e r p a p e r . E x i s t i n g m i l l m i x e r s showed c h a r g e d e v i a t i o n s f r o m 35-55%, w h e r e a s t h e MC m i x e r g a v e a c h a r g e d e v i a t i o n o f o n l y 5-10%. M i l l t r i a l s showed s a v i n g s o f a c t i v e c h l o r i n e ( 4 - 1 0 k g / T ) , r e d u c t i o n i n p u l p s h i v e c o n t e n t , I n c r e a s e 1n p u l p v i s c o s i t y , a n d i m p r o v e m e n t i n t e m p e r a t u r e u n i f o r m i t y . C o n c l u d e d t h a t " l a b o r a t o r y s i m u l a t i o n t e n d s t o u n d e r e s t i m a t e t h e p o t e n t i a l v a l u e o f I m p r o v e d m i x i n g " . Ko1 mod 1n ( 1984) E v a l u a t e s I m p r o v e d m i x i n g a f t e r a d d i t i o n o f Kamyr MC m i x e r s on t h e D1 t o w e r s o f 0(CD)EDED a n d (CD)EHDED b l e a c h p l a n t s . ( 1 ) C h l o r i n e d i o x i d e c h a r g e e v a l u a t e d u s i n g L1C1 t r a c e r c o n c e n t r a t i o n m e a s u r e d a t t h e t o p o f t h e t o w e r . ( 2 ) M i x i n g a s s e s s e d u s i n g s t a n d a r d d e v i a t i o n o f t e s t m e a s u r e m e n t s w e i g h t e d on t h e b a s i s o f e q u a l a r e a a t t h e t o w e r t o p . ( 3 ) Tower m i x i n g c o u l d be I m p r o v e d b y ( a ) i n c r e a s i n g t h e rpm o f t h e t o w e r m i x e r , ( b ) r e d u c i n g t h e t o w e r c o n s i s t e n c y , a n d ( c ) c h a n g i n g t h e c h e m i c a l d i s t r i b u t i o n t h r o u g h t h e i n j e c t o r n o z z l e s i n t o t h e t o w e r . ( 4 ) A d d i t i o n o f Kamyr MC m i x e r r e d u c e d m i x i n g 1 n h o m o g e n e 1 t y ( s t a n d a r d d e v i a t i o n ) f r o m 26 t o 2% [ 0 ( C D ) E D E D ] a n d f r o m 50 t o 5% [ ( C D)EHDED]. to to T A B L E D . 2 : LITERATURE SEARCH ( c o n t i n u e d ) ? MIXING OF PULP SUSPENSIONS tg § eg S3 >• tg S3 I CO A u t h o r s E x p e r i m e n t a l P r o g r a m S / o r R e p o r t C o n t e n t R e s u l t s & Comments L i e b e r g o t t e t a l . [ 1 9 8 4 ] P a t e r s o n 5 K e r e k e s [ 1984] L a b o r a t o r y I n v e s t i g a t i o n t o d e t e r m i n e how t h e i n t e n s i t y a n d d u r a t i o n o f m i x i n g a f f e c t e d t h e c h l o r i n a t i o n o f p u l p . C h l o r i n e w a t e r a t 4 g/1 was u s e d t o c h l o r i n a t e k r a f t p u l p a t 2% Cm o r l e s s . M i x i n g I n t e n s i t y was v a r i e d f r o m g e n t l e a g i t a t i o n t o v i o l e n t s t i r r i n g . T h e d i f f u s i o n / r e a c t i o n r a t e o f a q u e o u s c h l o r i n e t h r o u g h u n b l e a c h e d p u l p s u s p e n s i o n s o f 2.1 a n d 12.8% Cm was m e a s u r e d . ( 1 ) O n l y g e n t l e a g i t a t i o n o f s h o r t d u r a t i o n was r e q u i r e d t o p r o v i d e a d e q u a t e m i x i n g f o r d e l i g n i f i c a t i o n . ( 2 ) P r o l o n g e d g e n t l e a g i t a t i o n i s b e n e f i c i a l f o r s h l v e r e d u c t 1 o n . (3 ) I n c r e a s e d a g i t a t i o n b e y o n d t h e l e v e l r e q u i r e d t o i n i t i a l l y u n i f o r m l y d i s p e r s e t h e r e a c t a n t t h r o u g h o u t t h e p u l p was n o t b e n e f 1 c i a l . ( 1 ) C h l o r i n e w i l l d i f f u s e 3-5 mm t h r o u g h a 2 . 1 % Cm s u s p e n s i o n a n d 1-2 mm t h r o u g h a 12.8% Cm p u l p s u s p e n s i o n i n o n e h o u r . ( 2 ) The d i s t a n c e t h a t c h l o r i n e w i l l d i f f u s e i n a n y g i v e n t i m e d e c r e a s e s a s t h e mass c o n c e n t r a t i o n o f t h e p u l p s u s p e n s i o n i n c r e a s e s . ( 3 ) The d i s t a n c e b e t w e e n ' c l u m p s ' o f c h l o r i n e s h o u l d be r e d u c e d b e l o w t h e d i s t a n c e t h a t c h l o r i n e w i l l d i f f u s e i n t h e t i m e a v a i l a b l e i n t h e r e s i d e n c e t o w e r . T h i s w i l l e n s u r e t h a t d i f f u s i o n c o m p l e t e s t h e mass t r a n s f e r a n d g i v e s g o o d m i x i n g . P a t t y s o n [1984 ] R e p o r t o u t l i n e s t h e b e n e f i t s o b t a i n e d when D1 m i x i n g was i m p r o v e d by r e p l a c i n g an i n - l i n e s t a t i c m i x e r w i t h a Kamyr MC ' h i g h s h e a r ' m i x e r . CEDED s e q u e n c e . ( 1 ) R e d u c e d o c c u r r a n c e o f s h i v e s i n p u l p . ( 2 ) R e d u c e d t h e c h e m i c a l c o n s u m p t i o n o f c h l o r i n e by 1.9 kg/ADt an d c h l o r i n e d i o x i d e b y 1.3 k g / A D t . S1nn [ 1 9 8 4 ] R e p o r t s b e n e f i t s when a c o n v e n t i o n a l s i n g l e s h a f t c h l o r i n e d i o x i d e m i x e r was r e p l a c e d w i t h a Kamyr h i g h s h e a r m i x e r on a C(E/H)HEDP s e q u e n c e . R e d u c e d c h l o r i n e d i o x i d e c o n s u m p t i o n b y 2 3 % (medium b r i g h t n e s s ) a n d 10% ( h i g h b r i g h t n e s s ) . No a b s o l u t e c h e m i c a l c o n s u m p t i o n f i g u r e s a r e r e p o r t e d . to to TABLE D.2: LITERATURE SEARCH ( c o n t i n u e d ) : MIXING OF PULP SUSPENSIONS ft 3 ti A u t h o r s E x p e r i m e n t a l P r o g r a m 8>/or R e p o r t C o n t e n t R e s u l t s 8 Comments B a c k 1und 5 P a r m l n g [ 1 9 8 5 ] B e r g n o r e t a l [ 1985) B r e e d ( 1 9 8 5 ] M i x i n g 1 n h o m o g e n e 1 t 1 e s a r e s i m u l a t e d u s i n g c o m p u t e r m o d e l l i n g . P u l p b r i g h t e n i n g a n d s h l v e r e d u c t i o n 1n c h l o r i n e d i o x i d e b l e a c h i n g a r e t r e a t e d . M e a s u r e d m a c r o s c a l e m i x i n g o f i n d u s t r i a l t o w e r m i x e r s . T h e m i x i n g d y n a m i c s o f a n IMPCO h i g h s h e a r m i x e r w e r e s t u d i e d 1n a p i l o t s c a l e f a c i l i t y . N aCl was u s e d a s a t r a c e r . ( 1 ) ( 2 ) ( 3 ) The d i s t r i b u t i o n o f c h l o r i n e d i o x i d e In p u l p b l e a c h i n g a f f e c t s f i b r e b l e a c h i n g a n d s h l v e b l e a c h i n g In d i f f e r e n t ways due t o d i f f e r e n c e s 1n r e a c t i o n k i n e t i c s . I m p r o v i n g m i x i n g w i t h o u t o t h e r c h a n g e s g i v e s b e t t e r b r i g h t n e s s a n d n o r m a l l y a l o w e r s h l v e c o n t e n t a f t e r t h e 01 s t a g e . I n c e r t a i n c i r c u m s t a n c e s I m p r o v e d m i x i n g r e s u l t s i n h i g h e r p u l p s h l v e c o n t e n t . ( 1 ) ( 2 ) ( 3 ) A s s e s s e d m a c r o s c a l e m i x i n g a n d e x p r e s s e d m i x i n g g o o d n e s s u s i n g t h e c o e f f i c i e n t o f v a r i a t i o n ( s t a n d a r d d e v i a t i o n o f m e a s u r e m e n t s d i v i d e d b y t h e mean). F o u n d t h a t m i x e r m a c r o m l x l n g was e n h a n c e d by: ( a ) r e c o n f i g u r i n g t h e m i x e r h o u s i n g , ( b ) c h a n g i n g c h e m i c a l I n j e c t i o n l o c a t i o n , a n d ( c ) a d d i n g v e l o c i t y g e n e r a t o r s t o t h e r o t o r p e r i m e t e r . The a b o v e c h a n g e s r e d u c e d t h e c o e f f i c i e n t o f v a r i a t i o n f r o m +53% t o +7%. § ft 1 CO H a r k o n e n [ 1 9 8 5 ] A new b r e e d o f medium c o n s i s t e n c y m i x e r s h a v e b e e n d e v e l o p e d w h i c h r e l y o n ' f l u i d i z i n g ' t h e MC p u l p s u s p e n s i o n . An e q u a t i o n t o d e t e r m i n e t h e power r e q u i r e d t o ' f l u i d i z e ' a p u l p s u s p e n s i o n In a MC m i x e r i s d e r i v e d . ( 1 ) ' F l u i d i z a t l o n ' I s t h e t e r m g i v e n t o t h e p o i n t w h e r e a p u l p s u s p e n s i o n b e c omes t u r b u l e n t . T h i s was I n d i c a t e d by a n I n f l e c t i o n p o i n t on a p l o t o f t h e s h e a r s t r e s s v s . t h e s h e a r r a t e ( t o r q u e v s . rpm) 1n e x p e r i m e n t a l t e s t s . ( 2 ) S t a t e s t h a t " . . . I n t h e f l u i d i z e d s t a t e t h e p u l p s u s p e n s i o n has t h e same f l o w p r o p e r t i e s a s w a t e r . . . " ( 3 ) When t h e s h e a r s t r e s s a t a l l p o i n t s w i t h i n t h e t e s t c hamber e x c e e d t h e d i s r u p t i v e s t r e s s o f t h e s u s p e n s i o n ' f l u i d l z a t l o n ' o c c u r s . ( 4 ) E q u a t i o n s f o r c o m p u t i n g t h e power r e q u i r e d t o ' f l u i d i z e ' a r e d e r i v e d a n d s a m p l e c a l c u l a t i o n s made. A g r e e m e n t w i t h I n d u s t r i a l m i x e r s 1s f o u n d . to to 00 TABLE D.2: LITERATURE SEARCH ( c o n t t n u e d ) : MIXING OF PULP SUSPENSIONS fa § fa S3 I CO A u t h o r s E x p e r i m e n t a l P r o g r a m S / o r R e p o r t C o n t e n t R e s u l t s & Comments Kuoppamak 1 [ 1985] M e r e d i t h [ 1985] O l d s h u e a n d D e V M e s [ 1985] P e t t e r s s o n e t a l . [ 1985] P u l p m i x i n g a s s e s s e d u s i n g a r a d i o t r a c e r t e c h n i q u e . R e v i e w e d u s e o f t h e W e y e r h a u s e r "swept a r e a " m i x e r f o r MC m i x i n g . P i l o t s c a l e e x p e r i e n c e Is r e v i e w e d . D i s c u s s e s m i x i n g p r i n c i p l e s o f p a p e r p u l p s l u r r i e s In C S T ' s . R e p o r t s c h e m i c a l s a v i n g s a c h i e v e d by I m p r o v e d c h l o r i n a t i o n m i x i n g u s i n g a Sunds SMA m i x e r . ( 1 ) M e a s u r e d RTD c u r v e s f o r m i x i n g c h e s t s . ( 2 ) P o t e n t i a l t o o b t a i n h i g h f r e q u e n c y I n f o r m a t i o n ( s m a l l -s c a l e m i x i n g ) I n f o r m a t i o n f r o m t h e d e t e c t o r s i g n a l . ( 1 ) "Swept a r e a " p e g m i x e r . ( 2 ) Recommended s w e p t a r e a s ( t o t a l a r e a swept o u t by t h e r o t a t i n g p e g s p e r t o n o f p u l p p r o d u c t i o n ) f o r d i f f e r e n t b l e a c h i n g a p p l i c a t i o n s , r a n g i n g f r o m 6 5 , 0 0 0 m'/T f o r b r o w n s t o c k o x y g e n b l e a c h i n g t o 6,000 m'/T f o r c h l o r i n e a n d c h l o r i n e d i o x i d e b l e a c h i n g . ( 1 ) S u p p l i e r p a p e r . ( 2 ) SMA m i x e r r e p l a c e d a s t a t i c a n d a P e n n w a l t m i x e r In s e r i e s a n d r e s u l t e d 1n s a v i n g s o f 2.5 k g / B D t c h l o r i n e a n d r e d u c e d CEK number by 0.3 u n i t s . ( 3 ) E s t i m a t e d t y p i c a l s a v i n g s o f 1.4 k g c h l o r i n e d 1 o x i d e / A D T f o r a b r o w n s t o c k K a p p a number o f 30, a n d s a v i n g s o f 0.95 k g c h l o r 1 n e / A D T f o r a K a p p a number o f 20. R e e v e e t a l . Medium c o n s i s t e n c y c h l o r i n a t i o n 1s s t u d i e d i n a ( 1 ) G a s e o u s c h l o r i n e a d d e d t o MC p u l p s u s p e n s i o n s i n a [ 1 9 8 5 b ] h i g h I n t e n s i t y l a b o r a t o r y m i x e r . ' f l u i d l z e d s t a t e ' . ( 2 ) E n e r g y t r e a t m e n t o f f i b r e s i n t h i s l a b m i x e r i s a n o r d e r o f m a g n i t u d e h i g h e r ( 1 8 0 Md/t) t h a n t h e 7 - 1 4 MJ/t c o n s u m e d In i n d u s t r i a l m i x e r s . ( 3 ) T h e r e i s some e v i d e n c e o f m o d e r a t e p u l p b e a t i n g d u r i n g l a b o r a t o r y c h l o r i n a t i o n . ( 4 ) F o u n d t h a t MC c h l o r i n a t i o n In t h e h i g h i n t e n s i t y m i x e r i s o n l y s l i g h t l y more e f f i c i e n t t h a n LC c h l o r i n a t i o n i n t h e same m i x e r . C i t e s m a r g i n a l s a v i n g s o f c h l o r i n e a n d s i m i l a r s h l v e b l e a c h i n g e f f i c i e n c y . to to TABLE 0.2: LITERATURE SEARCH ( c o n t i n u e d ) : MIXING OF PULP SUSPENSIONS ft I g ft S3 1 C O A u t h o r s E x p e r i m e n t a l P r o g r a m S / o r R e p o r t C o n t e n t R e s u l t s & Comments A b e r c r o m b 1 [ 1986 ] P a t e r s o n & K e r e k e s [ 1986 ] R o b l t a l 1 l e [ 1987) S u n d s h i g h I n t e n s i t y m i x e r s were u s e d t o r e p l a c e e x i s t i n g c h l o r i n e ( s t a t i c ) a n d D1 ( p e g - t y p e ) m i x e r s In a (CD)EDED b l e a c h i n g s e q u e n c e . ' M i c r o s c a l e ' a s s e s s m e n t o f low c o n s i s t e n c y p u l p m i x e r s u s i n g a n o v e l s a m p l i n g t e c h n i q u e a n d t h e r e s i d u a l c h l o r i n e c o n t e n t o f t h e f r e e 11qu1d p h a s e . R e p o r t s on t h e r e p l a c e m e n t o f a C a n r o n p e g m i x e r b y an IMPCO MC m i x e r on t h e D1 s t a g e o f a ( C D ) ( E 0 ) D E D b l e a c h p l a n t . ( 1 ) R e p o r t s s a v i n g s o f c h l o r i n e (1.4 k g / t ) , c h l o r i n e d i o x i d e (2.94 k g / t ) , s o d i u m h y d r o x i d e ( 2 . 1 0 k g / t ) , a n d low p r e s s u r e s t e a m ( 1 7 0 0 k g / h r ) . ( 2 ) R e p o r t s I n c r e a s e d p u l p s h l v e c o n t e n t . ( 1 ) U s e d D a n c k w e r t s ' I s a n d L s t o a s s e s s m i x i n g g o o d n e s s . ( 2 ) Compared m i l l m i x i n g t o " g o o d " a n d " p o o r " l a b o r a t o r y m l x 1 n g . ( 3 ) The r a n k i n g o f ' m i c r o s c a l e ' m i x i n g among v a r i o u s m i l l m i x e r s showed s i g n i f i c a n t d i f f e r e n c e s . ( 4 ) C o u l d n o t d e t e r m i n e w h e t h e r t h e o b s e r v e d d i f f e r e n c e s 1n m i x i n g g o o d n e s s were s i g n i f i c a n t f o r p u l p c h l o r i n a t i o n . ( 1 ) An Improvement 1n m i x i n g e f f i c i e n c y was I n d i c a t e d b y : ( a ) Improvement In t e m p e r a t u r e u n i f o r m i t y a r o u n d t h e p e r i p h e r y o f t h e m i x e r o u t l e t , ( b ) I n c r e a s e d 01 s t a g e pH, ( c ) r e d u c e d c h l o r i n e d i o x i d e r e s i d u a l , a n d ( d ) r e d u c e d c h l o r i n e d i o x i d e u s a g e by 0.4 k g / t . ( 2 ) I n s t a l l a t i o n o f t h e MC m i x e r r e s u l t e d 1n a n I n i t i a l I n c r e a s e 1n p u l p s h l v e c o n t e n t . A c h a n g e m b l e a c h p l a n t o p e r a t i n g s t r a t e g y ( r e d u c i n g t h e D1 t o w e r t e m p e r a t u r e ) a l l o w e d m a i n t e n a n c e o f f i n a l p u l p b r i g h t n e s s a n d e l i m i n a t e d t h e s h l v e p r o b l e m . The c h a n g e a l s o r e s u l t e d 1n s t e a m s a v i n g s . B e r r y ( 1 9 8 7 ] S u r v e y r e s u l t s o f h i g h I n t e n s i t y m i x e r s u s e d ( 1 ) F o u r m a i n s u p p l i e r s o f h i g h I n t e n s i t y m i x e r s : o n C a n d D s t a g e s Is r e p o r t e d . B e l o 1 t - R a u m a , I n g e r s o l 1 - R a n d , Kamyr, a n d S u n d s - D e f I b r a t o r . ( 2 ) M i l l s r e p o r t c h e m i c a l s a v i n g s on I n s t a l l a t i o n o f h i g h I n t e n s i t y m i x e r s : 7 - 8 k g / t c h l o r i n e a n d 2 - 2 . 4 k g / t c h l o r i n e d i o x i d e . to TABLE D.2: LITERATURE SEARCH ( c o n t i n u e d ) : MIXING OF PULP SUSPENSIONS E x p e r i m e n t a l P r o g r a m &/or A u t h o r s R e p o r t C o n t e n t R e s u l t s & Comments C a m e r o n ( 1 9 8 7 ] S u n d s h i g h i n t e n s i t y m i x e r s r e p l a c e d a n R e p o r t s s a v i n g s o f 9 k g c h l o r 1 n e / a d t a n d 1n-11ne s t a t i c (CD) a n d a s i n g l e s h a f t m i x e r 1.2 k g c h l o r i n e d 1 o x 1 d e / a d t . (D1) on a ( C D ) ( E 0 ) D E D b l e a c h p l a n t . P a g e a u [ 1 9 8 7 ] A Kamyr MC pump a n d s i n t e r e d m e t a l s p a r g e r a r e u s e d f o r o x y g e n a d d i t i o n t o o x i d a t i v e e x t r a c t i o n s t a g e on a ( C D ) ( E O ) D E D s e q u e n c e . P u l p p a s s e s t h r o u g h a n MC pump a n d i m m e d i a t e l y i n t o t h e s p a r g e r e l e m e n t ( a 10 m i c r o n s i n t e r e d m e t a l p i p e o f s i x i n c h e s i n s i d e d i a m e t e r ) f o l l o w e d i m m e d i a t e l y by a n o r i f i c e a n d c o n t r o l v a l v e . T h i s e n s u r e s g o o d m i x i n g o f t h e o x y g e n w i t h t h e p u l p . C 1 r u c c 1 e t a l . D i r e c t o x y g e n I n j e c t i o n 1s c o m p a r e d w i t h d y n a m i c E f f i c i e n t e x t r a c t i v e o x i d a t i o n was m a i n t a i n e d when [ 1 9 8 7 ] m i x i n g f o r e x t r a c t i v e o x i d a t i o n o n a C ( E 0 ) H H t h e s t e a m m i x e r a n d Kamyr m i x e r were b y p a s s e d . s e q u e n c e b l e a c h i n g e u c a l y p t u s k r a f t . S team a n d o x y g e n were a d d e d I m m e d i a t e l y d o w n s t r e a m o f a Kamyr MC pump. D e t a i l s o f t h e o x y g e n / s t e a m I n j e c t i o n s y s t e m were n o t p r o v i d e d . TABLE D.3: LITERATURE SEARCH: Y I E L D STRESS OF PULP FIBRE SUSPENSIONS fa § fa 1=3 1 C O V 1 s c o m e t e r C h a r a c t e r i s t i c s : P u l p T y p e Mass F i t t o E q u a t I o n A u t h o r s T y p e / D i m e n s i o n s a n d P r o p e r t i e s C one. Cm (%) Y(Pa)=a.Cm**b an d r ' O b s e r v a t i o n s a n d Comments H e a d 5 D u r s t [ 1957] manual 1y o p e r a t e d s h e a r t e s t e r . v a r i e t y o f wood p u l p s 1 - 6 b = 2.88 b d e t e r m i n e d f o r a b l e a c h e d h a r d w o o d s u l f i t e . D a t a t a k e n f r o m f i g u r e 3. T h a l e n 6 Wahren [ 1 9 6 4 a ] e l a s t o - v 1 s c o m e t e r A v a r i e t y o f wood p u l p s w ere t e s t e d 0.40 -• 7.2 b • 1 .22 -2.09 ( 1 ) D e f i n e d t h e " u l t i m a t e s h e a r s t r e n g t h " as t h e maximum s h e a r s t r e s s t h a t c a n be t r a n s f e r r e d by t h e n e t w o r k . ( 2 ) F o r B i r c h NSSC, 8 0 % y i e l d , r e f i n e d t o 1 9 . 5 ° S R , b was f o u n d t o be 1.88. K a l 1 n t n e t a l . [ 1974] e l a s t o v 1 s c o m e t e r - 3 u n b l e a c h e d s u l f i t e 2 2 ° S R 1 . 4 - 7.0 a » b = r ' = 1 . 16 2. 16 0.988 D a t a t a k e n f r o m f i g u r e 1. D u f f y [ 1 9 7 5 ] m o d i f l e d F i s h e r & P o r t e r s h e a r t e s t e r v a r i o u s wood p u l p s 0.9 - 5.5 a -b = r i = 22 .5 2.24 0. 998 C o r r e l a t i o n I s g i v e n f o r an u n b l e a c h e d k r a f t p i n e . D a t a t a k e n f r o m f i g u r e 3. D u f f y & T l t c h e n e r [ 1975] m o d i f l e d F i s h e r 5 P o r t e r s h e a r t e s t e r b l e a c h e d k r a f t p 1 ne 0.95 • - 3.2 a = b = r ' = 13.4 2.28 0.983 C o m p a r e d q u a s i - s t a t i c m e t h o d s o f y i e l d s t r e n g t h d e t e r m i n a t i o n w i t h f l o w m e t h o d s . to cc to APPENDIX D. LITERATURE SEARCHES z o — ZJ t> 1/1 01 3 UJ C CU - CO +J C u. o U Q-w _i I 0. CJ o: U . < o UJ in co CO tu ui a: a 3 I-K CO < a o UJ _i f- UJ CO D c JZ TJ •H 0) TJ TJ -~ 01 CD 3 10 r t_ o <0 - 0J co t-t- CO ai a> 0J CD i— <o •»- T> £> at <i- C l TJ - 3 •r-c TJ E 3 E •H O 0J CO TJ O C CO C c »- c CO CO -0 da TJ OJ <- a ai O 0 c — o +> TJ C- OJ 3 QJco f_ > a L_ a oi 0 OJ OI 0J QJ TJ CO 3 — c C OJ a a c — c_ (Q TJ TJ C 0 «- co 11 TJ 0J 0J 3 C ai •H E co in 0 0 c 10 — •— CO CO (_ C 01 c CO a a cn OJ Q. L gi 0J (0 6 co a »— <- a TJ > c O 3 0J X 3 0 CO CO i_ 0) CJ a o OJ a o to E 01 e CO £ /-^ '—- '—- +> 13 0 CM CO ~-O o —- u. c « O 0 E V *- CJ ~ •H - I_ 4^ CO CO - 3 a TJ u_ o-^  C UJ CO CO o JZ 3 < co co cc cn oi o en QJ CD C r-c 01 3 — o co t cn • »- cn cn • • - oi O o CN CO • 1 in o ^  i CO c 0 E o OJ £ CJ CJ 6 TJ *> TJ o8 C «- cv TJ OJ (0 CO JZ - OJ +> I_ o £ JZ ^~ CO TJ .* CO u o H- o QJ QJ QJ ai i- CO r- ai 0- - JZ TJ •— OJ 3 JZ >. -H O OJ a a i— 10 o h TJ L to JZ XI 10C OJ QJ O i c ai a co a — CO CS M- Ql *~ CO <«-— 0 n m C CO E a D TJ CO 3 L. c — •»• c as CO C OJ L. C C 3 .Q a JC CO CO 3 O -* CO c O QJ •H c_ in I_ c_ c QJ in c 0 OJ QJ +J — 0 Q. O +^  QJ !- \ — CO ~- CO E OJ oi in TJ oO QJ £. L. QJ 0 a C QJ •f QJ +• O O > OJ ~- l_ c TJ cn CO 1- E it- QJ c OJ C !_ -~ t- — — JZ CO O — CO > co o TJ co OJ c — Ql O - JZ 0 >.JZ o E u_ 10 o o in CO cn in TABLE D.4: LITERATURE SEARCH: YIELD STRESS OF MAN-MADE FIBRE SUSPENSIONS A u t h o r s V I s c o m e t e r C h a r a c t e r i s t i c s : T y p e / D1mens1ons M a t e r i a l s a n d M a t e r i a l P r o p e r t i e s M a t r i x F 1 b r e Volume Cone. Cv (•/.) F i t t o E q u a t I o n Y ( P a ) = a . C v * * b a n d r ' O b s e r v a t i o n s Comments a n d R o s l n g e r e t a l [1974 ] O n o n g i e t a l ( 1 9 7 7 ] H o r l e & P l n d e r [ 1979] F e r r a n t 1 -S h 1 r e l y c o n e & p l a t e r = 35.00 mm 9 = 5.322 mrad w a t e r a n d p o l y s t y r e n e l a t e x w i t h a 1 urn 1num t r i c h l o r i d e 8. p o l y ( a c r y l 1 c a c i d ) , PAA We 1 s s e n b e r g r h e o g o n 1 o m e t e r c o n e 6V p l a t e d = 75 mm 9 = 2" M o d i f l e d H a a k e RV 1 MVIIP c u p ( 4 2 . 0 mm) w a t e r / N a C l / C V I I P bob ( 2 0 . 2 mm) d e x t r a n g a p w i d t h = 10.9 mm p o l y s t y r e n e 1n d i e t h y l p h t h a l a t e p o l y e t h y l e n e g l y c o l ( P E G ) / c r y s t o l I t e a s b e s t o s 0.2 - 0.8 ( b y mass) d = 1 = 20 -50 nm 0.6 -2 .3 mm 2.3 -9.5 mm t 1 t a n a t e d < 0.5 „m A > 40 0.5 - 5.0 n y l o n 17 = 4 3 . 1 ym = 0.987 -6.72 mm = 22.9 -156 a = 141 b = 2.09 r'= 0.837 ( f o r Cm) a = 2.12 b = 2.50 r'= 0.979 a = 3.11 b = 3.73 r'= 0.984 ( 1 ) P o l y s t y r e n e l a t e x showed N e w t o n i a n b e h a v i o u r . ( 2 ) Y i e l d s t r e s s f o r f i b r o u s s u s p e n s i o n s . ( 3 ) H y s t e r e s i s a n d n o n - l i n e a r i t y o b s e r v e d . ( 4 ) C o r r e l a t i o n g i v e n f o r a c o m p l e x d i s p e r s i o n o f a s b e s t o s 1n p o l y s t y r e n e l a t e x , 2% t o t a l s o l i d s , w i t h a s b e s t o s s o l i d s (Cm) v a r y i n g f r o m 0.2 t o 0.8% A p p a r e n t y i e l d s t r e s s was f o u n d t o be p r o p o r t i o n a l t o C v * * 3 . ( 1 ) Y i e l d t o r q u e r e p r o d u c a b l e t o ± 1 2 % o f a v e r a g e v a l u e . ( 2 ) Y i e l d s t r e s s d e p e n d a n t o n v i s c o s i t y o f m a t r i x m a t e r i a l . ( 3 ) Y i e l d s t r e s s i n c r e a s e d w i t h f i b r e a s p e c t r a t i o . ( 4 ) F i b r e o r i e n t a t i o n f o u n d a f t e r s h e a r 1ng. ( 5 ) F i t g i v e n f o r 5.03 mm f i b r e 1n 10% P E G / w a t e r / d e x t r a n / 1 m o l e N a C l . 1 s fa 1 Co K 5 co TABLE D.4: LITERATURE SEARCH ( c o n t i n u e d ) : Y I E L D STRESS OF MAN-MADE FIBRE SUSPENSIONS V i s c o m e t e r M a t e r i a l s a n d F i t t o C h a r a c t e r i s t i c s : M a t e r i a l P r o p e r t i e s V olume E q u a t 1 o n T y p e / C o n e . Y ( P a ) = a . C v * * b O b s e r v a t i o n s a n d A u t h o r s D i m e n s 1 o n s M a t r i x F i b r e Cv (%) a n d r ' Comments fa § t i >—i g fa S3 1 K i t a n o & K a t a o k a [ 1 9 8 1 a ] K i t a n o 8> K a t a o k a [ 1981b] R h e o m e t e r , RM-1 r = 40 mm 9 = 4° Rheogon i o m e t e r RGM 115-S r = 46.4 mm 6 = 4" a s a b o v e s i 1 1 c o n e o i 1 ,,= 100 P a . s v1ny1 o n d 0.3 - 5.0 m 1 = A = 11 .3 26.8 1.22 -3.22 mm 45.3 112.5 120. 1 0.0149 2 .50 0.958 s111 c o n e o i 1 ,,= 1600 P a . s , 546 P a . s . 210 P a . s v i n y l o n 0.43 - 7.65 a =1.23E-05 d i m e n s i o n s b = 6.17 a s a b o v e r'= 0.963 ( 1 ) ( 2 ) ( 3 ) ( 1 ) ( 2 ) ( 3 ) A p p a r e n t y i e l d s t r e s s a t low f i b r e c o n t e n t . Y i e l d v a r i e d a s C v * * 3 f o r A = 45.3 b u t d e p e n d e n c e l o w e r f o r A = 112.5 a n d 120.1. P o s t u l a t e d t h a t Y i e l d v a r i e s d u e t o i n t e r a c t i o n s b e t w e e n f i b r e s , t h e v i s c o m e t e r w a l l s . A, f i b r e l e n g t h a n d d i a m e t e r , a n d f i b r e f l e x l b i 1 1 t y . F i t g i v e n f o r 1=1.22 mm, d=26.8 pm. A p p a r e n t y i e l d s t r e s s i n c r e a s e d w i t h Cv a n d A. Y i e l d s t r e s s n o t a f f e c t e d by v i s c o s i t y o f m a t r i x . F i t g i v e n f o r 1=1.22 mm, d=26.8 „m, i/ » 1600 P a . s . Han [ 1 9 8 1 ] W e l s s e n b e r g I n d o p o l L100 g l a s s b e a d «5 - « 4 5 a = 0.0325 D a t a t a k e n f r o m F i g 3.6, p . 9 3 . r h e o g o n l o m e t e r ( N e w t o n i a n ) d=5-<*45 pm  .0b = 2 .06 r ' = 0. .992 CN5 co TABLE D.5: LITERATURE SEARCH: T E N S I L E STRESS OF MAN-MADE AND PULP FIBRE FLOCS M a t e r i a l s a n d F i t t o M a t e r i a l P r o p e r t 1 e s V o l u m e E q u a t I o n T e n s 11e C o n e . o ( P a ) » a . C v * * b O b s e r v a t i o n s a n d A u t h o r s T e s t e r M a t r i x F i b r e Cv (%) a n d r» Comments G a r n e r [ 1 9 8 6 ] i m p r o v i s e d a 1 r B I e a c h e d 1.2 - 5.7 a = 13.5 ( 1 ) F i t t e d d a t a t o j = a p * * b w h e r e t e n s 11e s o f t w o o d b = 2.33 0 « b u l k d e n s i t y ( k g / m * * 3 ) , g i v i n g t e s t e r k r a f t (BSK) r«» 0.648 b v a l u e s o f : BSK=2.3, BHK=2.3, RMP1=3.3 a n d RMP2=2.7. B l e a c h e d 2.8 - 7.7 a « 2.55 ( 2 ) F i t t e d a l 1 d a t a t o : har d w o o d b = 2.34 a = 5.8E-04 ( ( 1 / j e A / C m ] ) * * 2 . 2 4 k r a f t (BHK) r ' = 0.710 w h e r e : A « a s p e c t r a t i o R e f 1 n e r 3.5 - 9.7 a = 0.285 p * b u l k d e n s i t y (kg/m**3) m e c h a n i c a l b = 3.22 1 = a v e r a g e f i b r e l e n g t h p u l p (RMP1) r ' = 0.761 0 - a e r o d y n a m i c s p e c i f i c s u r f a c e ( 3 ) F i t t o t h e f o l l o w i n g e q u a t i o n : RMP2 3.8 - 12.4 a • b = r > . 1 .91 2.70 0.669 a = a ( C v * * b ) ( A * * c ) ( E * * d ) g a v e : a=3.30E-10, b=2.73, c=5.04 a n d d=0.35 w i t h r ' = 0 . 6 2 7 . ft to § ft is S3 1 Co S o s z y n s k i [ 1 9 8 7 ] T h w l n g A l b e r t t e n s 11e t e s t e r 3 3 % s u c r o s e / w a t e r s o l ' n n y l o n 66 3.03 12.3 2.64 ( 1 ) T e n s i l e s t r e n g t h v a r i e d w i t h Cv d S 19.7 - r a i s e d t o t h e 2.64 po w e r . 44.2 um ( 2 ) 'Type C f l o e s ' t e s t e d . H e r e a 1 s 2.7 - a r i s e s d u e t o f r i c t i o n b e t w e e n t h e 6.2 mm e l a s t l c a l l y b e n t f i b r e s t h a t c o m p r i s e t h e f l o e . 1 s 2.95 mm 4, .93 • • 13.7 a » 83.5 ( 3 ) J u s t i f i e d c o m p a r i s o n b e t w e e n A 3 66.7 b a 2.22 t e n s i l e a n d s h e a r b e c a u s e s t r e n g t h 1s c a u s e d b y f r i c t i o n 1 e 4.97 mm 4, .98 • - 8 . 3 6 a a 237 p r o d u c e d b y t y p e C c o h e s i o n i n A E 113 b m 2.02 b o t h c a s e s . ( 4 ) C o r r e l a t i o n s g i v e n f o r d « 44.2 um 1 B 6.26 mm 3 .04 • • 7.61 a s 62.2 f i b r e s . A s 142 b s 3.23 ( 5 ) I f o r i g i n a l d a t a i s a n a l y s e d u s i n g l i n e a r r e g r e s s i o n t e c h n i q u e s l o w e r v a l u e s o f b a r e d e t e r m i n e d . F o r e x a m p l e , f o r 1=2.95 mm, d=44.2 um a n d A • 66.7, l i n e a r r e g r e s s i o n g i v e s : a » 97.5, b = 2.03 a n d r f = 0.641. to co TABLE 0.6: LITERATURE SEARCH: VISCOSITY OF FIBRE SUSPENSIONS V i s c o m e t e r M a t e r i a l s a n d E x p e r i m e n t a l C h a r a c t e r i s t i c s : M a t e r i a l P r o p e r t i e s Volume D a t a T y p e / Cone. O b s e r v a t i o n s a n d A u t h o r s D i mens i o n s M a t r i x F i b r e Cv (%) C v ( % ) . Comments Nawab S Mason D r a g e c o a x i a l c a s t o r o i 1 r a y o n 0.047-1.34 0. 305 1 . 049 ( 1 ) W e ( s s e n b e r g e f f e c t i n c r e a s e d w i t h A. [ 1958] c y 1 i n d e r ,, = 2.5 Pa . s A = 43 - 0. 523 1 . 087 ( 2 ) V i s c o s i t y s h e a r a n d t i m e d e p e n d e n t 356 0. 637 1 . 107 a t h i g h v o l u m e t r i c c o n c e n t r a t i o n . 0. 895 1 . 157 ( 3 ) H i g h a s p e c t r a t i o p a r t i c l e s d e f o r m e d o n s h e a r i n g . ( 4 ) D a t a g i v e n f o r A = 113 r a y o n f i b r e . S t e e n b e r g & R o t a t i n g w a t e r u n b l e a c h e d a p p r o x . 1 0. 89 (D Cv e s t i m a t e d a s 2*Cm. J o h a n s s o n d i sk s u l f i t e 1-5 2 1 . 2 ( 2 ) V i s c o s i t i e s e s t i m a t e d a t a n [ 1 9 5 8 ] s h e a r p u l p 2. . 5 2 . 0 a p p a r e n t s h e a r r a t e o f 1 0 s 1/s. t e s t e r 7 8 ° S R 3 2 . 3 ( 3 ) N o n - N e w t o n i a n b e h a v i o u r a b o v e 4 5. 4 Cm = 1%. 5 9 . 5 Z i e g e l [ 1 9 7 0 ] Haake R o t o v i s c o p o l y m e r i c g l a s s 1.64-2.36 (D D e v e l o p e d a n e q u a t i o n t o r e l a t e f l u i d s : A = 500 s u s p e n s i o n v i s c o s i t y t o s u s p e n s i o n - p o l y e t h e r d i o l a n d f i b r e p r o p e r t i e s . - p o l y b u t e n e ( 2 ) T h e p o l y m e r s u s e d were N e w t o n i a n - p o l y c h l o r o p r e n e o v e r s h e a r r a t e s u s e d . - p o l y u r e t h a n e ( 3 ) T y p i c a l d a t a : F o r 2.36% Cv g l a s s f i b r e i n p o l c h l o r o p r e n e , (,r = 35.0. C o r e y [ 1 9 7 2 ] c o n c e n t r i c 6 1 % s u c r o s e / g l a s s 0.26-6.7 0 .26 1 . 12 ( 1 ) S t u d i e d s u s p e n s i o n v i s c o s i t y i n t e r m s c y 1 i n d e r w a t e r 0. .53 1 . 29 o f f i b r e - l i q u i d i n t e r a c t i o n s . v 1 s c o m e t e r N u j o l 1 . 07 1 . 47 ( 2 ) I n c r e a s e d t e m p e r a t u r e r e d u c e d s i 1 1 c o n e o i 1 2 . 13 2 . 82 s u s p e n s i o n v i s c o s i t y p r o p o r t i o n a t e p r o p y l e n e g l y c o l 2 .67 3 . 23 t o r e d u c t i o n i n s u s p e n d i n g medium v i s c o s i t y . ( 3 ) D a t a g i v e n f o r g l a s s f i b r e i n 6 1 % s u c r o s e / w a t e r . N i c o d e m o a n d We 1 s s e n b e r g p o l y e t h y 1 e n e g l a s s 1-7 1 .0 1 . 12 N i c o l a i s [ 1 9 7 4 ] r h e o g o n i o m e t e r ox i d e A = 37.8 3 .0 1 . 3 50 mm d i a m e t e r 5 .0 1 . 5 2° c o n e a n g l e 7 .0 1 . 85 I o ra to to CO APPENDIX D. LITERATURE SEARCHES — 2 n o 3 V) C 2 -. UJ 0 . c in o D o in U J X cc u ca cc -i < u. UJ co u. O UJ or > 73 t-r- « < U l CC O UJ CJ E CJ ~ s: r— • -r- •F C 0) II V TJ -r- O) O) C 0) 3 3 •r- OJ < ra E •H 10 in 41 -t- 01 0) V <_ i 0 c in in (0 H-XI Ifl a - 10 CO o — in E TJ 0) a) > *- t -••- c C_ [_ - > O 01 o o l_ -H c o •H a c 01 10 -r- O • 0 <n •r- TJ •— t— - o C 3 3 •-> in > >. O JO C V cu •F •F - CO •- CO i - in O • > 0) • in in £- — C 1— 3 CO 0 o CO ^  O CL 0 o a a - 0 o TJ in in in Q. V <(-c +•* O t- - CO CO ai (0 o > > O 3 c c ai f TJ t r in o in c a < CD co a) ai > o c 1- 0 > > (- E -r- -r-0 ai i - TJ — t_ i—• Ul — •r- •F C -F c - O •H 10 — 10 10 a co CO 1- co cn (0 •H .— i— 0) C O) +J > c co co 0) > OJ SL O -r- CO c C_ d> 3 Q cc o cc 01 CJ •—• a — 01 E Ifl E n 0 CN CN O) oCJ . co •H ID O O CM 00 CM O O c c ai (0 1 CM CO 1— P) (fl T-E •H T -(0 -c_ a '—- o o a *-O CM UT) CO CO X > i n O U l CJ ~- CO O T- CM t u) r> O o CO ai .—. in E o TJ c c 1 •— 0 CO O o > o > u tf) 1— o E E i a. 1 E i n -r-Cl co CM CM P) c OI CM • CM O 01 O o T - CJ  • • i n CM in c_ in CN <— CM — CO cu in > T- •r- (0 II c it II n TJ -H u. i — c l_ o i < > TJ ^ < (0 01 a CO o 1— I_ (0 a. •— C_ TJ 0 o cn ai <o C •»- co in 01 0) CO (0 c c c Q. E 01 X O m o 0 +^  •r- is> a. 0 O O CO C -•- **- O E +^  -O r— 1— (0 O O •«- 1- ti E m 01 in ^ o 1 c_ C_ E 01 0) in CC •H E in c 0) E ai 0 c_ - E E E c_ \ > ai £_ E O c/> * r O ai ai in l_ -H CD -- i o 4^  a c (0 cu •F O ° c in u> o in o >. 01 — E a 0 -"T 10 K E — 0 E O l - ^ > £- - 0 O II 1 O ll 1 ca O a in 0) 0) E c co - x: 1- © C d C CD o o > cc cc cc CO JC TJ 0 c CO 10 •F 1—I <0 (_ r -0) r -><n in a) - ,—' c E — 0 CO o JC c £ o — CO CO in — •F 0) CO -< E X A p p e n d i x E F ib re Suspens ion Y i e l d Stress Test D a t a Data for all yield stress tests are given in Tables E . l to E . l l . These tables include the average mass concentration and standard deviation of the fibre suspensions tested. The mass concentration was determined by oven drying pulp samples to constant weight in a convection oven at 105°C. The standard deviation was either measured directly or estimated from the standard deviation of the stock fibre suspension knowing the dilution factor. The rotor used for each yield stress determination is specified, and the factors required to convert the torque measured into yield stress are given in Table A . l . Those tests made with the Haake RV12 used housing RVH1, while those made with the pulp fluidizer used housing PFH1 (the wide-gap). The minimum, average, maximum, and standard deviation of each test set are reported, along with the number of individual tests made at a given condition, and the maximum shear rate and the ramp time. Finally the bulk density is reported for tests made with the pulp fluidizer where the gas content of the pulp is expected to be significant. The bulk density and mass concentration, together with the fibre properties, permit calculation of the volumetric concentration. The measured yield stresses for all tests are given in Table E.14 with the corre-sponding mass concentration, bulk density and volumetric concentration. Correlations obtained fitting the yield data to the equation Ty — aCmb 239 APPENDIX E. YIELD DATA 240 are given in Table E.15. The consistency range of the data, the number of data points used for the correlation, the values for a and b and their 95% confidence intervals, and the regression coefficient (for the logarithmic fit) are also included. The results of multiple linear regression fits to the equation Tv = aCvbEcAd are given in Table E.16. The table gives the specification of the system for which the correlation was developed, the consistency range and the number of data points used for the regression fit, the values of lna,6,c and d, and the standard error of these estimates. This allows the computation of confidence intervals for each parameter. For example a 1 0 0 x ( l — 7 ) confidence interval for b can be computed using the following equation [Le and Tenisci, 1978] b = b± i( M -m-i , i- 7 /2)(s.e.(6)) (E. l ) where t(M-m-i, 1-7/2) is the 100x ( l—7/2) percentage point of the t-distribution with M — m — 1 degrees of freedom, M is the overall degrees of freedom of the data set. Where no weighting occurs (as for the calculations here) it equals the numbers of observations, m equals the number of independent variables in the equation, s.e (6) is the standard error of b, and 7 is one minus the significance level for the confidence limit (for example, if the signif-icance level is 0.95, 7 is 0.05). A regression equation calculated with outliers excluded 1 is given for each system. The goodness of fit can be estimated using r 2. Where a dash (-) appears in the table, either xThe points excluded were outside the 95% confidence interval for the original regression equation. APPENDIX E. YIELD DATA 241 that variable was not varied in the test or it did not enter the regression equation with enough significance to be included. APPENDIX E. YIELD DATA 242 CO >- » O H » r-« E in O in o * c o \ 1 1 1 i 1 i i 1 1 1 i i 1 CD r- i in _i Z 0) 0) 01 O in 3 L T-CD Q w in cc o *t V UJ ^ O o o o O o O O o O O O o X c i 1 i i UJ to -~ CM CM CM CM CM CM CM CM CM CM CM CM CM £ E 1- £ T-1 * O o o O O O o O o o O O o so:* « < c CO Tf— TJ Tj TJ TJ Tt TJ TJ TJ TJ TJ TJ i 1 i i X UJ — to to ID CD ID CO ID ID ID < X E £ </l w or UJ CO as *- i - 01 O CM CM o o CM O o CO o o CM (0 o CM s o 00 LU Z 1-> co in r- in co cu in CO O o o O Q O O CM CM 01 co OI r- CM cu CM CO O o o o CM CO cn o 0) CD CM — TJ T- r-CO t~ CO T— OI r- co T - T - T - 0) in tD CO CO co CO TJ T  O to CO T-CO o O o o 0. X t~ to f- in O 01 ID cu Ul UJ CU w ' < CO 01 CM ID £ O O co ID TJ co CO tD o cn r- TJ TJ CM CO co CO T— CO in T- r- CO in CO T— co r- r» T - CO UJ CC (-CO CM in CO CO TJ TJ TJ o CO CM T  CO OI o O o o o _1 cs in to CO O CM TJ cu cu cu UJ cu cu > CO CM r- CO TJ < O O CO to t- co T- CO (0 T- to t~ T- I- CM CO TJ >- CM TJ CO CM in CD CO ~- CM TJ tn in CM ^ CO CO TJ TJ CD r- o 01 O o o z tn TJ O CD O CO u> cu UJ LU CO CO CO £ o O CO in CO CD TJ o in CO 1- T- CD TJ T - T-CM f- O 1- in r~ CM TJ CO TJ CM cc o CO m m CO a CL CL TJ TJ TJ CO CM T-f- "D "3 —> • — i »—i t—4 a. CL a CL a. CL T- CO T -o a. CL CL CL > > > _J _1 _ i _ J _ i _ l u_ u. Li_ U-or o o u CJ £ £ £ * *: ¥ 0. CL CL CL > in in e- O CO 0) in t~ CO CO cn CM .—* cu O O O T— CM CO CO TJ TJ TJ ID O 00 Q o O o O o O O O o o TJ TJ CM O CO O O O O O o O O O O O o o O o o O E O u o 1- <T T  CD CO O in O in O in in o o CD - ' TJ ID co o > O o O o CM CM CO CO CO TJ in o in CO CO < CO CO TABLE E,2: YIELD STRESS OF SEMI-BLEACHED KRAFT PULP: SBK-4 £g . *0 STOCK Cm (%) ROTOR YIELD STRESS ( P a ) NUMBER Of T E S T S MAXIMUM SHEAR (m1n**-1) TIME t o M. SHEAR ( m i n ) BULK DENSITY (kg/m**3) AVG S.DEV MIN AVG MAX S.DEV 1 . G 0.12 MVIP 11.3 19.0 25.3 4.43 10 1 .0 60.0 -1 . G 0. 12 MVIP 11.9 18.4 20. 2 2.58 10 1 .0 6.0 -1 . G 0. 12 MVIP 12.G 18.8 25.8 4. 14 10 1 .0 0.6 -1 .6 0.12 MVIP 11.9 17.6 22.8 2.95 10 8.0 0.6 -1 . G 0. 12 MVIP 19.3 23.4 28.8 3.67 10 64.0 0.6 -to CO TABLE E.3: Y I E L D STRESS OF STONE GROUNDWOOD PULP: SGW-1 STOCK Cm (%) ROTOR YIELD STRESS ( P a ) NUMBER Of T E S T S MAXIMUM SHEAR (m1n**-1) TIME t o M. SHEAR ( m i n ) BULK DENSITY (kg/m**3) AVG S.DEV MIN AVG MAX S.DEV 0.8 0.027 CPJB1 0.277 0.330 0.389 0.0385 11 1 .0 6.0 -1 .0 0.034 CPJB1 0.904 0.935 0.994 0.0278 11 1 .0 2.0 -1 .5 0.051 CPUB1 3.54 3.62 3.71 0.0588 10 1 .0 2.0 -2.0 0.069 MVIP 7.03 8.29 8.90 0.525 1 1 64.0 12.0 -3.0 0. 10 MVIP 42.9 44.6 46.9 1 .73 10 64.0 12.0 -4.0 0. 14 KLP4 92 .4 103 131 11.3 11 64.0 12.0 -5.0 0.17 KLP4 140 157 172 9.42 12 64 .0 12.0 -6.0 0.20 KLP4 268 319 394 37.4 16 6 4 . 0 12.0 -8.0 0.27 KLP1 484 782 1.05E03 170 16 64 .0 12.0 -12.4 0.39 PF1 4.39E03 5.24E03 6.31E03 659 10 - - 9 6 0 - 1 0 1 0 17.5 0.36 PF1 8.56E03 9.71E03 1.06E04 728 6 - - 9 8 0 30. 8 0. 12 PF1 1.14E04 1 - - 660 30. 8 0.30 PF3 2.40E04 2.74E04 2.99E04 2.03E03 6 - - 5 9 0 - 6 3 0 APPENDIX E. Y I E L D D A T A 245 3 a. < cj *—< Z < I cj LU £ O £ or > » t- * e * to \ J Z n 3 UJ CD Q w or o < f l i l ^ X c UJ LO £ E t- £ 3 * £ or * c-> < C x u c < I £ £ L O w LU LO CO <<- I -£ O LO 3 LU Z t -or o o or E U CJ o CD < < C/l o or cj 3 LO z o 3 _ l O or CD Z o a c cu o Q Ul CO < , >- * 1- * >-i E ^ LO \ t 1 i i -1 Z 0) 3 L u JC CO a w or 0 < •H L u ^ o o o o X c LU LO CM CM CM CM £ E *-1- £ £ l 3 * o O O o £ or * « < c T— T— TT X L J -•- CO < I E £ L O w or UJ CO CD <4- 1- CM CM T— O £ O co T— CM 3 cu z 1-> UJ T— Q o to d CO CO 0. X CM r-> - < . £ t TT CO to S3! 0— C/> a o O O _i CM CM CO T -cu > < O 6 CO U> >- CM V V r- IS z 0) r~ £ CM or o CD ca 03 0. i - 3 r> •o t—i o a. a a. > or o o CJ £ > «T t- 0) •—. LU O O O T -Q O O O o LO d d O d E CJ CJ o o o o o CO C3 > to CO d < APPENDIX E. YIELD DATA 246 < 00 o cc o z o _ l o CO <0 c or m o _i >-z c 0) o 00 00 > ID CO < / N CO >- * f- * n e * in \ i I i 1 i i 1 - J z ra u 00 Q w cco < +» L U ^ o o O O o o o X c Ui 00 — CM CM CM CM CM CM CM E E 1- E E i * E CC * o o O O o O O < C X Ul — T •* *T < I E ID u> (0 U> CD E oo w cc Ul oo CO <*- r— CM in in ID in E D 00 Z3 Ul Z > CM Ul 0) o o ID 00 d in co CM in CO T — CM uo CO (0 in o 0. X ID OJ > ' < 00 E d oo CM Cl o 1/) CM t 00 CM 01 U> 1-(/) CO •>]• o Q o ID Ul _ l a CM tr in O Ul > CM < d d oo CM CM 0) > -•— in CM »-V CM 1 A co z CM CO 0) E d CM CM ID o ID O 1-~* CC o m 00 o. CM , *— *-t- -3 •• ~> CL. '• a. a CL o Cv CL > _ l _i _ i _ l cc O O '• E 2C ^ * * > CM CO in CO Ul o o O o O O O s« Q O o o O O O O 00 O o O o o O O E O sc o o r-I- O m O o o O O </) ca > CM CM ID CO o in < < 3 00 o cc o 3 Z oo oo cc m z o >-z c o o 00 CO < co >- » 1- * >-i E X o o \ • i 1 1 1 1 1 _l Z 0) 3 iu jl ca a — cc o < o O o o o o o I c ui 01 — CM CO CM CM CM CM CM E E r-l h- E E 1 3 # E CC » o o o o O o O >-l < C X I U ' .— ID < X E CD ID (0 CD CD E 00 w CC Ul oo CO 1- CO * CD o CM O E O oo CM *~ OJZ 1-> Ul CM o in CO o 00 O 00 O in O CM CO CO T— in T— CM CM CO in O CL X CO r- O >—• < E CO *— 00 i- CM CM CO 00 in CM ID 00 CO oo 01 Ul CC 1-00 a o LD _i cs o CM O Ul > < CM 00 CD O CD I - CO > in CO 00 O CM CO in T •V z CO cn o 1—1 E ID 01 CM O ID CM CO CO in T _ CO cc o m CD a. T CO 1- "3 "3 t—i a a. CL a o CL CL > _i _i _ l _i cc CJ U E X. > CM CO CO in ID 00 .—. 1X1 o O O O O O O a O O O O O o O 00 o o O O O o O e CJ U o 1- in O o o O o O 00 > CM ID oo O < TABLE E.8: Y I E L D STRESS OF 15 D e n i e r 7 mm NYLON FIBRES i n a 3 3 % wt/wt SOLUTION o f SUCROSE i n WATER STOCK Cm (%) ROTOR YIELD STRESS ( P a ) NUMBER o f T E S T S MAXIMUM SHEAR (m1n**-1) TIME t o M. SHEAR ( m i n ) BULK DENSITY (kg/m**3) AVG S.DEV MIN AVG MAX S.DEV 0.3 0.0001 CPJB1 <.2 2 1 .0 2.0 -0.5 0.0002 CPJB1 0.88 1.11 1 .47 0.219 10 1 .0 2.0 -1 .0 0.0004 CPJB1 4 .62 7. 15 8.78 1 .54 1 1 1.0 2.0 -1 .0 0.0004 MVIP 0.94 1 .80 2.28 0.662 5 1 .0 2.0 -2.0 0.0008 KLP4 12.6 18.8 25.2 4. 10 10 1 .0 2.0 -3.0 0.0012 KLP4 31 .2 50.3 86.8 17.6 12 1 .0 2.0 -4.0 0.0016 KLP4 63.6 120 227 53.3 12 1 .0 2.0 -TABLE E.9: Y I E L D STRESS OF 15 D e n i e r 5 mm NYLON FIBRES In WATER STOCK Cm (%) ROTOR YIELD STRESS ( P a ) NUMBER Of T E S T S MAXIMUM SHEAR (m1n**-1) TIME t o M. SHEAR ( m i n ) BULK DENSITY (kg/m**3) AVG S.DEV MIN AVG MAX S.DEV 2.0 0.002 MVIP 12.9 14.5 23. 1 3.54 10 1 .0 2.0 -4.0 0.003 KLP4 15.6 31.5 44 .0 8.05 10 1 .0 2.0 -6.0 0.005 KLP4 52.8 143 232 45.5 12 1 .0 2.0 -APPENDIX E. YIELD DATA 248 co >- * f— * n E SC 00 \ _1 Z 01 D Ul i BO-or o < I c 111 CO T -E E o IN o CN < 3 O z < I z o 3 _1 o to 0) <0 c or m O O 01 < at CL CO CO cu oc I-co o £ I 3 * E Or * i-i < c X U 1 » < I E E CO w or LU CO £0 1-1-E 0 CO 3 cu Z I-o CL CO l/> or o o or E O * o o 01 01 o in 01 o u> co o ID 0> o o 01 T «t CO in CM 01 O ci CD co O CM o co o co ID 01 01 Tf CO CO CO t-m 3 CL m 3 CL CJ CO 3 o. o a > > E Tt a Tt a. r-0) CD CD Tt a CD CO 0) ID Tf a co CD CM CD r-CD 01 Tt O tn O Tt CL CL CD in 01 a 2C 01 d o in O t-co < APPENDIX E. YIELD DATA 249 1—* CO >- * 1- * M E X. to \ I i i i 1 1 1 1 i _ l Z 0) CD Q w DC O < u O O O O o o O o O I C UJ CO ~- CN Tt Tt Tt Tt Tt Tt Tt Tt s E t—1 K £ £ l * £ CC * o o o o o o O o o •H < C x u < I E £ 10 w CC LU LO CO <4- 1- CN T- o CM T— o CM t-T— E 0 LO 3 LU Z t-> CC 0) CM LU 0) CO CM O 1-Tt o CM to o CM *- T" CO to O O o to in to co o LO CM r-ca CO CO a. X CD CM •—-< o t in CM Tt CO CO E CO f-LO T- O O CO CO to i - O CM to T- CN CO co T- CO LU t-LO a _ i C3 a> u> in UJ > CO T-Tt o o 0) CO Tf t—1 < CO co CO to O) >- T- CO CM Tt O d d to T - Tt CM in T -Z 01 T in •—< CO 0) t~ in u> CO CM O co E O o in in at Tt CO O o O T— to CO CM Tt cc o ca CO CO a a. CL Tt TT TT "3 "3 •—i 4-4 CL a. a o CL 0. CL > > • > -1 _ i _ i cc o CJ o E E E X > UJ s? a 1 1 1 i l l 1 • i to E o O o 1- in in in O in O o o o to CJJ > O O O T- T- CM CM CO Tt < APPENDIX E. YIELD DATA 250 Table E.12: Yield stress of a 33.6% Cm semi-bleached kraft pulp as a function of volume concentration. PULP T Y P E : SBK-1 SENSOR USED: PF1 PULP MASS CONCENTRATION: 3 3 . 6 ± 0.08 % BULK D E N S I T Y ( k g / m * * 3 ) VOLUME CONC. C v (%) Y I E L D S T R E S S ( P a ) 146 9 . 45 127 . 3 223 14 .44 8 2 0 . 6 266 17 .22 1287 351 22 . 72 2 8 8 6 4 1 0 2 6 . 5 4 5 2 2 7 4 8 6 3 1 . 4 6 5 8 6 3 548 35 . 48 1.028E04 594 38 . 45 1.151E04 624 4 0 . 4 0 1.470E04 6 3 0 4 0 . 7 8 1.407E04 Table E.13: Yield stress of a 30.8% Cm stone groundwood pulp as a function of volume concentration. PULP T Y P E : SGW-1 SENSOR USED: PF1 PULP MASS CONCENTRATION: 3 0 . 8 ± 0.12 % BULK D E N S I T Y ( k g / m * * 3 ) VOLUME CONC. C v (%) Y I E L D S T R E S S ( P a ) 204 9.47 ( 2 1 . 2 ) 292 13 . 55 7 6 3 . 9 366 16 . 99 1896 4 4 9 2 0 . 8 4 4 7 0 3 517 2 3 . 9 9 7 0 2 3 5 7 5 2 6 . 6 9 8 0 5 7 621 28 . 82 9 4 0 0 6 6 3 3 0 . 7 7 1.149E04 TABLE E.14: YIELD DATA FOR ALL TESTS FIBRE/SYSTEM: Se m i - B l e a c h e d K r a f t : SBK-1 F i b r e l e n g t h : 2.37 mm; F i b r e d i a m e t e r : 0.0300 mm; A= 79.0 FIBRE/SYSTEM: Se m i - B l e a c h e d K r a f t : SBK-1 F i b r e d e n s i t y : 1500 kg/m**3; S o l u t i o n d e n s i t y : 1000 kg/m**3 ( c o n t i n u e d ) Water R e t e n t i o n V a l u e (WRV): 1.260 kg/kg Cm B u l k Den. Cv Y Cm B u l k Den. Cv Y H (%) (kq/m**3) (%) (N/m**2) H 1%) (kq/m**3) (%) (N/m**2) 1 0.40 0.77 0.7680E+00 41 0 .80 1 .55 0.6371E+01 2 0.40 0.77 0.6628E+00 42 1 .00 1 .93 0.2998E+01 3 0.40 0.77 0.6196E+00 43 1 .00 1 .93 0.4779E+01 4 0.40 0.77 0.5459E+00 44 1 .00 1 .93 0.1396E+02 5 0.40 0.77 0.6114E+00 45 1 .00 1 .93 0.8809E+01 6 0.40 0.77 0.4676E+00 46 1 .00 1 .93 0.7683E+01 7 0.40 0.77 0.7096E+00 47 1 .00 1 .93 0.7777E+01 8 0.40 0.77 0.5845E+00 48 1 .00 1 .93 0.7496E+01 9 0.40 0.77 0.6044E+00 49 1 .00 1 .93 0.6372E+01 10 0.40 0.77 0.6780E+00 50 1 .00 1 .93 0.6090E+01 11 0.40 0.77 0.5144E+00 51 1 .00 1 .93 0.5903E+01 12 0.40 0.77 0.6430E+00 52 1 .50 2 .90 0.2624E+02 13 0.40 0.77 0.5109E+00 53 1 .50 2 .90 0. 1837E+02 14 0.40 0.77 0.5845E+00 54 1 .50 2 .90 0.1743E+02 15 0.40 0.77 0.5576E+00 55 1 .50 2 .90 0.2090E+02 16 0.40 0.77 0.5845E+00 56 1 .50 2 .90 0.3889E+02 17 0.40 0.77 0.6079E+00 57 1 .50 2 .90 0.2446E+02 18 0.40 0.77 0.6862E+00 58 1 .50 2 .90 0.4076E+02 19 0.40 0.77 0.5459E+00 59 1 .50 2 .90 0.3739E+02 20 0.60 1. 16 0.3215E+01 60 1 .50 2 .90 0.6560E+01 21 0.60 1. 16 0.3425E+01 61 1 .50 2 .90 0.2249E+02 22 0.60 1. 16 0.3636E+01 62 1 .50 2 .90 0.3045E+02 23 0.60 1 . 16 0.3566E+01 63 1 .50 2 .90 0.1630E+02 24 0.60 1. 16 0.3098E+01 64 1 .50 2 .90 0.2764E+02 25 0.60 1. 16 0.3402E+01 65 1 .50 2 .90 0.2755E+02 26 0.60 1 . 16 0.3706E+01 66 1'. 50 2 .90 0.2464E+02 27 0.60 1 . 16 0.3215E+01 67 1 .50 2 .90 0.1677E+02 28 0.60 1. 16 0.3121E+01 68 1 .50 2 .90 0.2296E+02 29 0.60 1. 16 0.3332E+01 69 1 .50 2. .90 0.1021E+02 30 0.60 1 . 16 0.3238E+01 70 1 .50 2 .90 0.2015E+02 31 0.80 1.55 0.5985E+01 71 1 .50 2 .90 0.2464E+02 32 0.80 1.55 0.6137E+01 72 1 .50 2 .90 0.2595E+02 33 0.80 1 .55 0.6582E+01 73 2 .00 3. .88 0.3514E+02 34 0.80 1 .55 0.5927E+01 74 2 .00 3 .88 0.2399E+02 35 0.80 1.55 0.6161E+01 75 2 .00 3. .88 0.3G07E+02 36 0.80 1.55 0.5494E+01 76 2 .00 3. .88 0.5856E+02 37 0.80 1 .55 0.6196E+01 77 2 .00 3 .88 0.4085E+02 38 0.80 1 .55 0.6114E+01 78 2 .00 3 .88 0.4170E+02 39 0.80 1 .55 0.6219E+01 79 2 .00 3. .88 0.4966E+02 40 0.80 1.55 0.6009E+01 80 2 .00 3, .88 0.5022E+02 FIBRE/SYSTEM: Semi- B l e a c h e d K r a f t : SBK-1 (c o n t inued) FIBRE/SYSTEM: S e m i - B l e a c h e d K r a f t : SBK-1 (c o n t inued) Cm B u l k Den. Cv Y Cm B u l k Den. Cv Y £ (%) (kg/m**3) (%) (N/m**2) _£ (%) (kg/m**3) (%) (N/m**2) 81 2 .00 3 .88 0 .3701E+02 121 3 .50 6 .82 0 .3559E+03 82 2 .00 3 .88 0 .4676E+02 122 3 .50 6 .82 0 . 4359E+03 83 2 .00 3 .88 0 .3148E+02 123 3 .50 6 .82 0 .5802E+03 84 2 .00 3 .88 0 .5303E+02 124 3 .50 6 .82 0 .5723E+03 85 2. .50 4 .86 0 .8700E+02 125 3 .50 6 .82 0 .4759E+03 86 2. .50 4 .86 0 ,8760E+02 126 3 .50 6 .82 0 .3904E+03 87 2 .50 4 .86 0 . 1038E+03 127 3 .50 6 .82 0 .3481E+03 88 2 .50 4 .86 0 .7080E+02 128 3 .50 6 .82 0 .2775E+03 89 2 .50 4. .86 0, ,8820E+02 129 3 .50 6 .82 0 4822E+03 90 2. .50 4. .86 0. 8160E+02 130 4. .00 7, .81 0, 5090E+03 91 2. .50 4. ,86 0. .1158E+03 131 4 .00 7 81 0 4512E+03 92 2 .50 4 .86 0 .7380E+02 132 4 .00 7, .81 0, .5121E+03 93 2 .50 4 .86 0. .5280E+02 133 4. .00 7. .81 0. 7544E+03 94 2. .50 4. .86 0. ,7260E+02 134 4, ,00 7, ,81 0. 5425E+03 95 3 00 5. .84 0. 1704E+03 135 4. ,00 7. 81 0. 7199E+03 96 3 .00 5. .84 0. ,1662E+03 136 4 .00 7. ,81 0. . 6895E+03 97 3, .00 5. .84 0, ,9840E+02 137 4. ,00 7. ,81 0. 4512E+03 98 3. .00 5. ,84 0. ,1182E+03 138 4. ,00 7. 81 0. 5739E+03 99 3. .00 5. .84 0. 1578E+03 139 4. 00 7. 81 0. 6642E+03 100 3. 00 5. 84 0. 1296E+03 140 5. ,00 9. ,80 0. 1237E+04 101 3. .00 5. ,84 0, 7560E+02 141 5. .00 9. 80 0. 1060E+04 102 3. ,00 5. .84 0. ,1146E+03 142 5. 00 9. 80 0. 1120E+04 103 3. .00 5. 84 0. 1194E+03 143 5. 00 9. 80 0. 9432E+03 104 3. .50 6. 82 0. 2694E+03 144 5. 00 9. 80 0. 1223E+04 105 3. .50 6. .82 0, ,2850E+03 145 5. .00 9. ,80 0. .1235E+04 106 3, .50 6, ,82 0. 2340E+03 146 5 00 9. 80 0. 9996E+03 107 3. .50 6. .82 0. 2394E+03 147 5. 00 9. 80 0. 1390E+04 108 3. 50 6. 82 0. 2736E+03 148 5. 00 9. 80 0. 8759E+03 109 3. 50 6. 82 0. 1740E+03 149 5. 00 9. .80 0. 8330E+03 110 3. ,50 6. .82 0. ,2520E+03 150 5, .00 9. 80 0. 1433E+04 111 3. .50 6. .82 0. 2250E+03 151 5. 00 9. 80 0. 1194E+04 112 3. 50 6. 82 0. 3792E+03 152 8. 00 15. 84 0. 6600E+04 113 3. 50 6. 82 0. 2040E+03 153 10. 60 964 19. 71 0. 4478E+04 114 3. 50 6. .82 0. 9780E+02 154 10. ,60 964 19. ,71 0. 5984E+04 1 15 3. .50 6. 82 0. 7920E+02 155 10. 60 964 19. 71 0. 5121E+04 116 3. 50 6. 82 0. 2058E+03 156 10. 60 964 19. 71 0. 7292E+04 117 3. 50 6. 82 0. 8040E+02 157 10. 60 964 19. 71 0. 5920E+04 118 3. 50 6. 82 0. 1080E+03 158 10. 60 964 19. 71 0. 4845E+04 119 3. 50 6 .82 0. 3720E+03 159 10. 60 964 19. 71 0. .6387E+04 120 3. .50 6, .82 0. 7370E+03 160 12. 00 24. 08 0. 1520E+05 FIBRE/SYSTEM: Sem1-Bleached K r a f t : SBK-1 (c o n t inued) Cm (%) B u l k Den. (kg/m**3) Cv (N/m**2) FIBRE/SYSTEM: Sem1-Bleached K r a f t : SBK-4 F i b r e l e n g t h : 1.94 mm; F i b r e d i a m e t e r : 0.0300 mm; A- 6 4 ? F i b r e d e n s i t y : 1500 kg/m**3; S o l u t i o n d e n s i t y : 1000 kg/m**3 Water R e t e n t i o n V a l u e (WRV): 1.290 kg/kg Cm Bulk Den. (kg/m**3) Cv (%) (N/m**2) 1 1 .62 3. 19 0.2202E+02 161 15. 10 956 27.83 0. 1325E+05 2 1 .62 3. 19 0.2202E+02 162 15. 10 970 28.22 0. 1235E+05 3 1 .62 3. 19 0.1574E+02 163 15. 10 970 28.22 0. 1262E+05 4 1 .62 3. 19 0.1340E+02 164 15. 10 970 28.22 0.1313E+05 5 1 .62 3. 19 0.2174E+02 165 15, 10 970 28.22 0.1187E+05 6 1 .62 3. 19 0.1134E+02 166 15. 10 970 28.22 0.1300E+05 7 1 .62 3. 19 0.2193E+02 167 33. ,40 346 22.27 0.1207E+05 8 1 .62 3. 19 0.1902E+02 168 33. 40 426 27.48 0.1839E+05 9 1 .62 3. 19 0.1762E+02 169 33. ,40 481 30.95 0.2173E+05 10 1 .62 3. 19 0.2530E+02 170 33, ,40 508 32.69 0.2217E+05 11 1 .62 3. 19 0.1883E+02 171 33. 40 524 33.78 0.2137E+05 12 1 .62 3. 19 0.1968E+02 172 33, ,40 531 34. 17 0.2601E+05 13 1 .62 3. 19 0.2024E+02 173 33. .40 542 34.94 0.3094E+05 14 1 .62 3. 19 0.2005E+02 174 33, .40 542 34.94 0.2386E+05 15 1 .62 3. 19 0.2024E+02 175 33, .40 555 35.71 0.3521E+05 16 1 .62 3. 19 0.1649E+02 176 33, .40 566 36.49 0.3857E+05 17 1 .62 3. 19 0.1808E+02 177 33 .60 146 9.45 0.1273E+03 18 1 .62 3. 19 0.1874E+02 178 33, .60 222 14.44 0.8206E+03 19 1 .62 3. 19 0.1190E+02 179 33, ,60 265 17.22 0.1287E+04 20 1 .62 3. 19 0.1996E+02 180 33. 60 351 22.72 0.2886E+04 21 1 .62 3. 19 0.1724E+02 181 33, .60 410 26.54 0.5227E+04 22 1 .62 3. 19 0.2108E+02 182 33. .60 486 31.46 0.5863E+04 23 1 .62 3. 19 0.1827E+02 183 33. .60 547 35.48 0.1028E+05 24 1 .62 3. 19 0.2577E+02 184 33. 60 593 38.45 0.1151E+05 25 1 .62 3. 19 0.2343E+02 185 33. .60 624 40.40 0.1470E+05 26 1 .62 3. 19 0.1921E+02 186 33, ,60 629 40.78 0.1407E+05 27 1 .62 3. 19 0. 1593E+02 28 1 .62 3. 19 0.1359E+02 29 1 .62 3. 19 0.1265E+02 30 1 .62 3. 19 0.2061E+02 31 1 .62 3. 19 0.1640E+02 32 1 .62 3. 19 0. 1499E+02 33 1 .62 3. 19 0.1687E+02 34 1 .62 3. 19 0.1190E+02 35 1 .62 3. 19 0.2277E+02 36 1 .62 3. 19 0.2061E+02 37 1 .62 3. 19 0. 1827E+02 38 1 .62 3. 19 0.1818E+02 39 1 .62 3. 19 0.1808E+02 40 1 .62 3. 19 0. 1687E+02 ft § ft ft to 2 to Cn CO FIBRE/SYSTEM: Semi-Bl e a c h e d K r a f t : SBK-4 ( c o n t i n u e d ) Cm Bulk Den. Cv Y H (%) (kg/m**3) (%> (N/m**2) 41 1.62 3. 19 O.2090E+02 42 1 .62 3. 19 0.2399E+02 43 1 .62 3. 19 0.1930E+02 44 1 .62 3. 19 0.1930E+02 45 1 .62 3. 19 0.2249E+02 46 1.62 3. 19 0.2680E+02 47 1.62 3. 19 0.2286E+02 48 1 .62 3. 19 0.2905E+02 49 1 .62 3. 19 0.2877E+02 50 1 .62 3. 19 0.2061E+02 FIBRE/SYSTEM: S t o n e Groundwood: SGW-I F i b r e l e n g t h : 0.61 mm; F i b r e d i a m e t e r : 0.0300 mm; A= 20.3 F i b r e d e n s i t y : 1500 kg/m**3; S o l u t i o n d e n s i t y : 1000 kg/m**3 Water R e t e n t i o n V a l u e (WRV): 0.840 kg/kg Cm Bulk Den. Cv Y M (%) (kg/nv**3) IX). (N/m**2) 1 0 .80 1 .21 0 .3507E+00 2 0 .80 1 .21 0 .2806E+00 3 0 .80 1 .21 0 .2771E+00 4 0 .80 1 .21 0 .3156E+00 5 0 .80 1 .21 0 .3390E+00 6 0 .80 1 .21 0 .3507E+00 7 0 .80 1 .21 0. .3507E+00 8 0 .80 1 .21 0 .3893E+00 9 0 .80 1 .21 0 .3706E+00 10 0 .80 1 .21 0. .3238E+00 11 0 .80 1 .21 0 .3121E+00 12 1, .00 1 .51 0 .9937E+00 13 1. .00 1 .51 0 9118E+00 14 1. .00 1 .51 0 .9153E+00 15 1. .00 1 .51 0 .9469E+00 16 1. ,00 1 .51 0. .9352E+00 17 1. 00 1 .51 0. .8966E+00 18 1. 00 1 .51 0. 9551E+00 19 1. .00 1 .51 0 .9036E+00 20 1. .00 1 .51 0, .9352E+00 21 1. .00 1 .51 0. 9551E+00 22 1. .00 1 .51 0, , 9352E+00 23 1. .50 2 .27 0. .3659E+01 24 1. 50 2. .27 0. .3706E+01 25 1. .50 2 .27 0. .3647E+01 26 1. .50 2 .27 0. 3624E+01 27 1. .50 2 .27 0, .3566E+01 28 1. .50 2 .27 0. 3624E+01 29 1. 50 2 .27 0. 3694E+01 30 1. .50 2 .27 0 .3542E+01 31 1. .50 2 .27 0 3589E+01 32 1. ,50 2 .27 0. 3542E+01 33 2. 00 3. .03 0. 7028E+01 34 2. 00 3 .03 0. 8620E+01 35 2. ,00 3 .03 0. .8152E+01 36 2. ,00 3 .03 0. .8620E+01 37 2. 00 3 .03 0. .8527E+01 38 2. 00 3. .03 0. 8527E+01 39 2. 00 3. .03 0, 8246E+01 40 2. .00 3 .03 0, 7777E+01 ra ra s to FIBRE/SYSTEM: S t o n e Groundwood: ( c o n t i n u e d ) SGW-1 FIBRE/SYSTEM: Ston e Groundwood: SGW-1 ( c o n t i n u e d ) Cm B u l k Den. Cv Y Cm Bulk Den. Cv Y ff (%) (kq/m**3) (%) (N/m**2) ff (%) (kg/m**3) (%) (N/m**2) 41 2 .00 3 .03 0 .8901E+01 81 6 .00 9 .22 0 .3780E+03 42 2 .00 3 .03 0 .8152E+01 82 6 .00 9 .22 0 .3138E+03 43 2 .00 3 .03 0 .8620E+01 83 6 .00 9 .22 0 .3390E+03 44 3 .00 4 .57 0 .4498E+02 84 6 .00 9 .22 0 .3120E+03 45 3 .00 4 .57 0 .4273E+02 85 6 .00 9 .22 0 .3288E+03 4G 3 .00 4 .57 0 .4629E+02 86 6 .00 9 .22 0 .2688E+03 47 3 .00 4 .57 0 .4685E+02 87 6 .00 9 .22 0 .2898E+03 48 3 .00 4 .57 0 .4629E+02 88 6 .00 9 .22 0 .3090E+03 49 3 .00 4 .57 0 .4170E+02 89 6 .00 9 .22 0 .2706E+03 50 3 .00 4 .57 0 .4432E+02 90 6 .00 9 .22 0 .2910E+03 51 3 .00 4 .57 0 .4544E+02 91 6 .00 9 .22 0 .2694E+03 52 3 .00 4 .57 0 .4544E+02 92 6 .00 9 .22 0 .3480E+03 53 3 .00 4 .57 0. .4338E+02 93 6 .00 9 .22 0 .3000E+03 54 3 .00 4 .57 0. .4348E+02 94 8, .00 12 .38 0. .7901E+03 55 4 .00 6 . 11 0. 1038E+03 95 8. .00 12 .38 0 6750E+03 56 4 .00 6 .11 0, 9360E+02 96 8. .00 12 .38 0 .1054E+04 57 4 .00 6 .11 0. .1314E+03 97 8. .00 12 .38 0 6395E+03 58 4. .00 6, ,11 0. ,1104E+03 98 8. .00 12 .38 0, ,8355E+03 59 4. ,00 6. ,11 0. .9420E+02 99 8, 00 12, ,38 0. .1079E+04 60 4. .00 6. ,11 0. 1050E+03 100 8. 00 12 ,38 0, 5758E+03 61 4. .00 6, ,11 0. 1098E+03 101 8. 00 12. ,38 0. 8575E+03 62 4. .00 6 .11 0. .9240E+02 102 8. .00 12. ,38 0, 6358E+03 63 4. .00 6, ,11 0. ,9540E+02 103 8. 00 12. 38 0. 7375E+03 64 4. ,00 6. .11 0. 1008E+03 104 8. 00 12. 38 0. 8257E+03 65 4. .00 6, 11 0. 9840E+02 105 8. 00 12. 38 0. 4839E+03 66 5. ,00 7. 66 0. 1416E+03 106 8. 00 12. 38 0. 9984E+03 67 5. ,00 7. 66 0. 1584E+03 107 8. 00 12. ,38 0. 7963E+03 68 5. ,00 7, 66 0. 1722E+03 108 8. 00 12. 38 0. 7411E+03 69 5. ,00 7. 66 0. 1644E+03 109 8. 00 12. 38 0. 9963E+03 70 5. 00 7. 66 0. 1608E+03 110 12. 40 959 17. 93 0. 5210E+04 71 5. 00 7. 66 0. 1680E+03 111 12. 40 959 17. 93 0. 4388E+04 72 5. 00 7 . 66 0. 1524E+03 112 12. 40 959 17. 93 0. 4494E+04 73 5. ,00 7. 66 0. 1518E+03 113 12. 40 959 17. 93 0. 4431E+04 74 5. 00 7. .66 0. 1584E+03 114 12. 40 959 17. 93 0. 6306E+04 75 5. 00 7, 66 0. 1476E+03 115 12. 40 1007 18. 82 0. 5436E+04 76 5. .00 7. 66 0. 1398E+03 116 12. 40 1007 18. 82 0. 5167E+04 77 5. 00 7. 66 0. 1518E+03 117 12. 40 1007 18. 82 0. 5972E+04 78 6. 00 9. 22 0. 3942E+03 118 12. 40 1007 18. 82 0. 5739E+04 79 6. 00 9. 22 0. 3546E+03 119 12. 40 1007 18. 82 0. 5272E+04 80 6. 00 9. 22 0. 2922E+03 120 17. 50 1000 26. 37 0. 8556E+04 1» ra § ra t-i to to ts2 Cn Cn FIBRE/SYSTEM: Sto n e Gromdwood: (c o n t I n u e d ) SGW-1 Cm Bulk Den. Cv ft (%) (kg/m**3) (%) (N/m**2) 121 17 50 1000 26 37 0 1028E+05 122 17 50 1000 26 37 0 1062E+05 123 17 50 1000 26 37 0 9482E+04 124 17 50 1000 26 37 0 9439E+04 125 17 50 1000 26 37 0 9884E+04 126 30 80 460 21 36 0 1180E+05 127 30 80 561 26 07 0 1640E+05 128 30 80 586 27 23 0 2634E+05 129 30 80 601 27 90 0 2858E+05 130 30 80 602 27 98 0 2751E+05 131 30 80 615 28 57 0 2398E+05 132 30 80 623 28 94 0 2814E+05 133 30 80 624 28 99 0 2982E+05 134 30 80 291 13 55 0 7639E+03 135 30 80 365 16 98 0 1896E+04 136 30 80 449 20 84 0 4703E+04 137 30 80 517 23 99 0 7023E+04 138 30 80 574 26 68 0 8057E+04 139 30 80 620 28 82 0 9400E+04 140 30 80 662 30 77 0 1149E+05 FIBRE/SYSTEM: Thermomechan1ca1 P u l p : TMP-1 F i b r e l e n g t h : 1.16 mm; F i b r e d i a m e t e r : 0.0300 mm; A= 38.7 F i b r e d e n s i t y : 1500 kg/m**3; S o l u t i o n d e n s i t y : 1000 kg/m**3 Water R e t e n t i o n V a l u e (WRV): 0.910 kg/kg Cm Bu l k Den. Cv Y tt (%) (kg/m**3) <%) (N/m**2) 1 0 70 1 u 0 2724E+00 2 0 70 1 11 0 3308E+00 3 0 70 1 11 0 3425E+00 4 0 70 1 11 0 3074E+00 5 0 70 1 11 0 2572E+00 6 0 70 1 11 0 3589E+00 7 0 70 1 11 0 3308E+00 8 0 70 1 11 0 3121E+00 9 0 70 1 11 0 2572E+00 10 0 70 1 11 0 2806E+00 11 0 70 1 11 0 3238E+00 12 1 00 1 58 0 1114E+01 13 1 00 1 58 0 1313E+01 14 1 00 1 58 0 1192E+01 15 1 00 1 58 0 1266E+01 16 1 00 1 58 0 1208E+01 17 1 00 1 58 0 1301E+01 18 1 00 1 58 0 1154E+01 19 1 00 1 58 0 1219E+01 20 1 00 1 58 0 1169E+01 21 1 00 1 58 0 1286E+01 22 1 50 2 38 0 6020E+01 23 1 50 2 38 0 6079E+01 24 1 50 2 38 0 6488E+01 25 1 50 2 38 0 6020E+01 26 1 50 2 38 0 6114E+01 27 1 50 2 38 0 6348E+01 28 1 50 2 38 0 5985E+01 29 1 50 2 38 0 6079E+01 30 1 50 2 38 0 5728E+01 31 1 50 2 38 0 6079E+01 32 2 00 3 17 0 8873E+01 33 2 00 3 17 0 8836E+01 34 2 00 3 17 0 7571E+01 35 2 00 3 17 0 8217E+01 36 2 00 3 17 0 8808E+01 37 2 00 3 17 0 9023E+01 38 2 00 3 17 0 8836E+01 39 2 00 3 17 0 8058E+01 40 2 00 3 17 0 8592E+01 -a ft to ft ft tri to to to FIBRE/SYSTEM: Thermomechanical P u l p : TMP-1 (c o n t inued) FIBRE/SYSTEM: Thermomechanical P u l p : TMP-1 (c o n t inued) Cm Bu l k Den. Cv Y H (%) (kq/m**3) (%) (N/m**2) 41 2 .00 3. 17 0 .7805E+01 42 2 .00 3. 17 0 .8901E+01 43 3 .00 4.78 0. .4216E+02 44 3 .00 4.78 0 .4001E+02 45 3 .00 4.78 0. .4573E+02 46 3 .00 4.78 0. .4282E+02 47 3. .00 4.78 0, 4310E+02 48 3. .00 4.78 0. 4085E+02 49 3 .00 4.78 0 .4188E+02 50 3 .00 4.78 0. .3654E+02 51 3 .00 4.78 0, .3542E+02 52 3 .00 4.78 0. .3823E+02 53 3. .00 4.78 0. .3954E+02 54 3 .00 4.78 0. .3487E+02 55 3. .00 4.78 0. .3692E+02 56 3 .00 4.78 0, 4451E+02 57 3. .00 4.78 0. 4170E+02 58 3. ,00 4.78 0. 4366E+02 59 3. .00 4.78 0. 3964E+02 60 4. 00 6.39 0. 1464E+03 61 4, .00 6.39 0. 1380E+03 62 4. 00 6.39 0. 1182E+03 63 4 00 6.39 0. .1578E+03 64 4 .00 6.39 0, .1302E+03 65 4, .00 6.39 0. .1410E+03 66 4. .00 6.39 0. 1134E+03 67 4. .00 6.39 0. 1218E+03 68 4. .00 6.39 0. 1116E+03 69 4. 00 6.39 0. 1272E+03 70 4. .00 6.39 0. 1260E+03 71 4. .00 6.39 0. .1056E+03 72 5. 00 8.02 0. 3473E+03 73 5 00 8.02 0. 3183E+03 74 5. .00 8.02 0. 3301E+03 75 5. .00 8.02 0. 2383E+03 76 5. .00 8.02 0. 3144E+03 77 5. 00 8.02 0. 2689E+03 78 5. .00 8.02 0. 3583E+03 79 5. .00 8.02 0. 3136E+03 80 5 .00 8.02 0, ,3003E+03 # Cm (%) Bulk Den. (kq/m**3) Cv (%) Y (N/m**2) 81 5 .00 8 .02 0 .2885E+03 82 6 .00 9 .65 0 .8447E+03 83 6 .00 9. .65 0 .8193E+03 84 6 .00 9 .65 0 .7727E+03 85 6 .00 9. .65 0 .6621E+03 86 6 .00 9. .65 0 .6976E+03 87 6. .00 9. .65 0 .8376E+03 88 6 00 9. 65 0 .8802E+03 89 6 .00 9 .65 0 .7757E+03 90 6, .00 9. ,65 0 .9623E+03 91 6. .00 9. .65 0 .8771E+03 92 6. 00 9. 65 0 .765GE+03 93 9. 20 956 13. 88 0 .4011E+04 94 9. .20 956 13. .87 0 .3177E+04 95 9. 20 976 14. 16 0 .3183E+04 96 9. 20 986 14. 32 0. 3711E+04 97 9. 20 984 14. 29 0. 3261E+04 98 9. 20 985 14. 29 0 2913E+04 99 9. 20 990 14. 37 0 .3308E+04 100 9. 20 989 14. 36 0. 2792E+04 101 9. 20 989 14. 36 0. 3416E+04 102 9. 20 1003 14. 55 0. 3383E+04 FIBRE/SYSTEM: 2 mm 15 d e n i e r N y l o n In 33% S u c r o s e s o l u t i o n F i b r e l e n g t h : 1.89 mm; F i b r e d i a m e t e r : 0.0449 mm; A= 42.1 F i b r e d e n s i t y : 1140 kg/m**3; S o l u t i o n d e n s i t y : 1140 kg/m**3 Water R e t e n t i o n V a l u e (WRV): 0.077 kg/kg FIBRE/SYSTEM: 3 mm 15 d e n i e r N y l o n i n 33% S u c r o s e s o l u t i o n F i b r e l e n g t h : 3.45 mm; F i b r e d i a m e t e r : 0.0449 mm; A= 76.8 F i b r e d e n s i t y : 1140 kg/m**3; S o l u t i o n d e n s i t y : 1140 kg/m*+3 Water R e t e n t i o n V a l u e (WRV): 0.077 kg/kg Cm Bulk Den. Cv Y Cm Bulk Den. Cv Y tt (%) (kg/m**3) (%) (N/m**2) It A%) (kg/m**3) it) ^ (N/m**2) 1 8. 00 8. 70 0. 4243E+01 1 2 .57 2. .80 0, 6550E+00 2 8. 00 8. 70 0. 4033E+01 2 2, .57 2 ,80 0, 6390E+00 3 8. 00 8. 70 0. 4080E+01 3 2. .57 2, .80 0. 4680E+00 4 8. ,00 8. 70 0, 3916E+01 4 2 .57 2 .80 0. .5460E+00 5 8. .00 8. 70 0. 2385E+01 5 2, .57 2, .80 0, , 2340E+00 6 8. 00 8. 70 0. 3495E+01 6 2, .57 2 .80 0. .5770E+00 7 8. ,00 8. 70 0. 2993E+01 7 2 .57 2 .80 0 .4440E+00 8 8. 00 8. 70 0. 2572E+01 8 2 .57 2, .80 0 .5460E+00 9 8. 00 8. 70 0, 2309E+01 9 2 .57 2, .80 0 .3390E+00 10 8. ,00 8. 70 0. 2969E+01 10 . 2 .57 2 .80 0 3510E+00 11 8. ,00 8. 70 0. 3273E+01 11 2, .57 2, .80 0, .3040E+00 12 10. .00 10. 88 0. 4198E+02 12 4' .00 4 .35 0 .2136E+02 13 10. ,00 10. 88 0. 3111E+02 13 4 .00 4, .35 0 . 1774E+02 14 10. .00 10. 88 0. 3317E+02 14 4 .00 4 .35 • s 0 .2555E+02 15 10, ,00 10. 88 0, 6465E+02 15 4 .00 4 .35 0 . 1243E+02 16 10. 00 10. 88 0. 2015E+02 16 4, ,00 4, .35 0 .1683E+02 17 10. ,00 10. 88 0. 6370E+01 17 4 .00 4 .35 0, ,2649E+02 18 10. .00 10. 88 0. .1760E+01 18 4, .00 4, .35 0, 2805E+02 19 10. 00 10. 88 0. 5032E+02 19 4, .00 4, .35 0. . 1351E+02 20 10, ,00 10. 88 0. 2108E+02 20 4 .00 4, .35 0, .1843E+02 21 10. 00 10. 88 0. 1359E+02 21 4, .00 4. .35 0. .1234E+02 22 10. 00 10. 88 0. ,1312E+02 22 4 .00 4 .35 0, .1524E+02 23 10. .00 10. 88 0, 8250E+01 23 4 .00 4. .35 0, .1274E+02 24 10. 00 10. 88 0. 5150E+01 24 4, ,00 4, .35 0, ,1990E+02 25 10, .00 10. ,88 0, .1087E+02 25 4 .00 4 .35 0. .1913E+02 26 10, .00 10. 88 0, 2221E+02 26 4 .00 4, .35 0, ,1815E+02 27 10. .00 10. 88 0. 3073E+02 27 6 .00 6 .53 0. .1095E+03 28 10, ,00 10, 88 0, 4395E+02 28 6 .00 6, .53 0. ,1332E+03 29 10. .00 10. 88 0. ,1124E+02 29 6. .00 6. ,53 0, ,1957E+03 30 10, .00 10, ,88 0, .4826E+02 30 6 .00 6, .53 0, 1727E+03 31 10. .00 10. 88 0, 4357E+02 31 6, .00 6. ,53 0, ,1572E+03 32 6, .00 6 .53 0. 1683E+03 33 6, ,00 6, .53 0. ,1802E+03 34 6, .00 6, ,53 0, 1778E+03 35 6, .00 6, .53 0, ,1944E+03 36 6, .00 6, 53 0. 9940E+02 37 6, .00 6, 53 0, 6290E+02 38 6 .00 6 53 0 8450E+02 - 39 6, ,00 6. ,53 0. 2417E+03 40 6. 00 6, ,53 0, 1785E+03 ft fa ft ft to to to FIBRE/SYSTEM: 3 mm 15 d e n i e r N y l o n In 33% S u c r o s e s o l u t i o n ( c o n t i n u e d ) Cm B u l k Den. Cv Y £ (%) (kg/m+*3) (%) (N/m**2) 41 6 .00 6 .53 0 .1203E+03 42 8. .00 8 .70 0 .1372E+03 43 8, .00 8 .70 0 .1062E+03 44 8 .00 8, .70 0 .1250E+03 45 8, .00 8, ,70 0, ,2777E+03 46 8. .00 8, .70 0, .2728E+03 47 8. .00 8, ,70 0, ,1160E+03 48 8. .00 8. 70 0, 9187E+03 49 8. .00 8, ,70 0. .1562E+03 50 8. .00 8, ,70 0. .1388E+03 51 8. .00 8. ,70 0. 2818E+03 52 8. .00 8. 70 0. ,2328E+03 53 8, ,00 8. ,70 0. ,1780E+03 54 8, .00 8. 70 0. 1584E+03 55 8. .00 8. 70 0. 2813E+03 56 8. .00 8. ,70 0. 2850E+03 57 8. .00 8. ,70 0. 2042E+03 58 10. 00 10. 88 0. 2034E+03 59 10. ,00 10. 88 0. .3687E+03 60 10. ,00 10. 88 0. ,2560E+03 61 10. 00 10. 88 0. 2683E+03 62 10. 00 10. 88 0. 8453E+03 63 10. .00 10. 88 0. ,3822E+03 64 10. 00 10. 88 0. 2940E+03 65 10. 00 10. 88 0. 5402E+03 66 10. ,00 10. 88 0. 2658E+03 67 10. 00 10. 88 0. 4226E+03 68 10. 00 10. 88 0. 4288E+03 69 10. ,00 10, 88 0. ,1703E+03 70 10. 00 10. 88 0. ,1084E+04 71 10. 00 10. 88 0. 4882E+03 72 10. ,00 10. 88 0. 4141E+03 FIBRE/SYSTEM: 5 mm 15 d e n i e r N y l o n i n 33% S u c r o s e s o l u t i o n F i b r e l e n g t h : 5.16 mm; F i b r e d i a m e t e r : 0.0449 mm; A- 115.0 F i b r e d e n s i t y : 1140 kg/m**3; S o l u t i o n d e n s i t y : 1140 kg/m**3 Water R e t e n t i o n V a l u e (WRV): 0.077 kg/kg Cm Bulk Den. Cv Y H (%) (kq/m**3) (%) (N/m**2) 1 1.50 1.63 0. 1948E+01 2 1 .50 1 .63 0.2018E+01 3 1 .50 1.63 0.1549E+01 4 1 .50 1.63 0.1769E+01 5 1.50 1.63 0.1543E+01 6 1 .50 1 .63 0.1442E+01 7 1 .50 1 .63 0.1648E+01 8 1 .50 1.63 0.1496E+01 9 1 .50 1.63 0.2728E+01 10 1 .50 1 .63 0.1543E+01 11 1 .50 1.63 0.2338E+01 12 1.50 1 .63 0. 1691E+01 13 1 .50 1 .63 0.2435E+01 14 1.50 1.63 0. 1679E+01 15 1 .50 1.63 0.2038E+01 16 1 .50 1.63 0.2545E+01 17 1.50 1.63 0.2241E+01 18 1.50 1.63 0.3351E+01 19 2.00 2. 18 0.8534E+01 20 2.00 2. 18 0.6336E+01 21 2.00 2. 18 0.8019E+01 22 2.00 2. 18 0.7283E+01 23 2.00 2. 18 0.9060E+01 24 2.00 2. 18 0.7482E+01 25 2.00 2. 18 0.7014E+01 26 2.00 2. 18 0.7996E+01 27 2.00 2. 18 0.1035E+02 28 2.00 2. 18 0.6979E+01 29 2.00 2. 18 0.8475E+01 30 2.00 2. 18 0.1140E+02 31 2.00 2. 18 0.9001E+01 32 2.00 2. 18 0.7599E+01 33 4.00 4.35 0.7871E+02 34 4.00 4.35 0.3992E+02 35 4.00 4.35 0.6259E+02 36 4.00 4.35 0.6793E+02 37 4.00 4.35 0.4217E+02 38 4.00 4.35 0.6522E+02 39 4.00 4.35 0.8171E+02 40 4.00 4.35 0.4685E+02 FIBRE/SYSTEM: 5 mm 15 d e n i e r N y l o n 1n 33% S u c r o s e s o l u t i o n ( c o n t inued) FIBRE/SYSTEM: 5 mm 15 d e n i e r N y l o n i n 33% S u c r o s e s o l u t i o n ( c o n t inued) Cm Bulk Den. Cv Y Cm Bulk Den. Cv Y H (50 (kq/m**3) (%) (N/m*+2) H (%) (kq/m**3) (%) (N/m**2) 41 4 .00 4 .35 0.4797E+02 81 10.00 10.88 0.4410E+03 42 4 .00 4 .35 0.3411E+02 82 10.00 10.88 0.8257E+03 43 4 .00 4 .35 0.7683E+02 83 10.00 10.88 0.3724E+03 44 4 .00 4 .35 0.5959E+02 84 10.00 10.88 0.9433E+03 45 4 .00 4 .35 0.6184E+02 85 10.00 10.88 0.8330E+03 46 4 .00 4 .35 0.4901E+02 86 10.00 10.88 0.3981E+03 47 4 .00 4 .35 0.7730E+02 87 10.00 10.88 0.3124E+03 43 4 .00 4 .35 0.5369E+02 88 10.00 10.88 0.2756E+03 49 6 .00 6 .53 0.1400E+03 89 10.00 10.88 0.3357E+03 50 6 .00 6 .53 0.1735E+03 90 10.00 10.88 0.4741E+03 51 6 .00 6 .53 0.2418E+03 91 10.00 10.88 0.3185E+03 52 6 .00 6 .53 0.3216E+03 53 6 .00 6. ,53 0.2340E+03 54 6 .00 6 .53 0.2430E+03 55 6 .00 6. ,53 0.2430E+03 56 6 .00 6. ,53 0.2220E+03 57 6 .00 6. ,53 0.2280E+03 58 6 .00 6. ,53 0.3270E+03 59 6 .00 6. ,53 0.2448E+03 60 6. .00 6. ,53 0.2136E+03 61 8 .00 8. 70 0.3395E+03 62 8. .00 8. ,70 0.6625E+03 63 8. .00 8. 70 0.3214E+03 64 8. 00 8. 70 0.3512E+03 65 8. .00 8. 70 0.6460E+03 66 8. .00 8. 70 0.1803E+03 67 8. 00 8. 70 0.4688E+03 68 8. 00 8. 70 0.6860E+03 69 8. 00 8. 70 0.7526E+03 70 8. 00 8. 70 0.1396E+03 71 8. 00 8. 70 0.1615E+03 72 8. 00 8. 70 0.1835E+03 73 8. 00 8. 70 0.3234E+03 74 8. 00 8. 70 0.3120E+03 75 8. 00 8. 70 0.1560E+03 76 8. 00 8. 70 0.3716E+03 77 8. 00 8. 70 0.2164E+03 78 8. 00 8. 70 0.8624E+03 79 8. 00 8. 70 0.3238E+03 80 8. 00 8. 70 0.2764E+03 fa fa t- l to to 2 to o FIBRE/SYSTEM: 7 mm 15 d e n i e r N y l o n In 33% S u c r o s e s o l u t i o n F i b r e l e n g t h : 7.12 mm; F i b r e d i a m e t e r : 0.0449 mm; A= 159.0 F i b r e d e n s i t y : 1140 kg/m**3: S o l u t i o n d e n s i t y : 1140 kg/m**3 Water R e t e n t i o n V a l u e (WRV): 0.077 kg/kg FIBRE/SYSTEM: 7 mm 15 d e n i e r N y l o n ( c o n t i n u e d ) i n 33°/ S u c r o s e s o Hit i o n Cm B u l k Den. Cv Y # (%) (kq/m**3) (50 (N/m**2) Cm Bulk Den. Cv Y # (50 (kg/m**3) (50 (N/m**2) 1 0 .50 0 .54 0. 1450E+01 2 0 .50 0 .54 0. ,1470E+01 41 3 .00 3. .26 0 .5280E+02 3 0 .50 0 .54 0. .1150E+01 42 3 .00 3. .26 0 .7000E+02 4 0 .50 0. .54 0. ,9900E+00 43 3. .00 3. .26 0 .4700E+02 5 0 .50 0 .54 0, 9500E+00 44 3 .00 3. .26 0 .3120E+02 6 0 .50 0. .54 0, 9500E+00 45 3. .00 3. ,26 0 .3240E+02 7 0 .50 0. .54 0. 9500E+00 46 3. .00 3. 26 0. .3360E+02 8 0 .50 0. .54 0. 8800E+00 47 3. .00 3. .26 0 .3870E+02 9 0 .50 0 .54 0. ,1290E+01 48 3, .00 3. .26 0 .4520E+02 10 0 .50 0 .54 0. .1020E+01 49 4. .00 4, .35 0 .1644E+03 11 1 .00 1 .09 0. 2280E+01 50 4. .00 4. .35 0 .1236E+03 12 1 .00 1 .09 0. . 1590E+01 51 4 .00 4. .35 0 . 1152E+03 13 1 .00 1 .09 0. .1560E+01 52 4 .00 4. .35 0 9150E+02 14 1 .00 1. .09 0. 9370E+00 53 4. .00 4. .35 0 .2064E+03 15 1 .00 1 .09 0. 2620E+01 54 4 .00 4 .35 0 .7200E+02 16 1 .00 1 .09 0, 6140E+01 55 4, .00 4. .35 0 .6840E+02 17 1 .00 1 .09 0. .8180E+01 56 4, .00 4. .35 0 .63G0E+02 18 1 .00 1. .09 0. .7010E+01 57 4. .00 4, .35 0 .2274E+03 19 1 .00 1 .09 0. 8010E+01 58 4, .00 4. .35 0 .1170E+03 20 1 .00 1 .09 0. 8490E+01 59 4. .00 4. .35 0 .1116E+03 21 1 .00 1. ,09 0. 8470E+01 60 4. ,00 4. .35 0 .8220E+02 22 1 .00 1 .09 0. 5670E+01 23 1 .00 1 .09 0. 4620E+01 24 1 .00 1, .09 0. 8290E+01 25 1 .00 1 .09 0. 8780E+01 26 1 .00 1. .09 0. 4950E+01 27 2 .00 2 . 18 0. , 2240E+02 28 2 .00 2 .18 0. 2520E+02 29 2 .00 2 . 18 0, .1860E+02 30 2 .00 2. . 18 0. ,1320E+02 31 2 .00 2. .18 0. 1500E+02 32 2 .00 2 . 18 0, .1260E+02 33 2 .00 2 . 18 0. 2150E+02 34 2 .00 2. . 18 0. 2100E+02 35 2 .00 2 . 18 0, .1980E+02 36 2 .00 2 . 18 0. 1870E+02 37 3 .00 3. .26 0. 5760E+02 38 3 .00 3 .26 0. 8680E+02 39 3 .00 3 .26 0. 6900E+02 40 3 .00 3, .26 0. 3900E+02 fa § fa X fa fa fa fa fa s to FIBRE/SYSTEM: 5 mm 15 d e n i e r N y l o n 1n Water F i b r e l e n g t h : 5.16 mm; F i b r e d i a m e t e r : 0.0449 mm; A= 115.0 F i b r e d e n s i t y : 1140 kg/m**3; S o l u t i o n d e n s i t y : 1000 kg/m**3 Water R e t e n t i o n V a l u e (WRV): 0.077 kg/kg Cm B u l k Den. Cv Y I (%) (kg/m**3) (%) (N/m**2) 1 2 .00 1 .91 0. .1040E+02 2 2 .00 1 .91 0. ,1290E+02 3 2. .00 1 .91 0. ,1500E+02 4 2 .00 1 .91 0. 2310E+02 5 2 .00 1 .91 0. ,1510E+02 6 2 .00 . 1 .91 0, ,1390E+02 7 2 .00 1 .91 0. ,1550E+02 8 2 .00 1 .91 0. 1510E+02 9 2 .00 1 .91 0. 1340E+02 10 2 .00 1 .91 0. ,1050E+02 11 4 .00 3 .84 0. 4000E+02 12 4 .00 3 .84 0. 3540E+02 13 4 .00 3 .84 0. 2360E+02 14 4. .00 3 .84 0. 4400E+02 15 4 .00 3 .84 0. 3100E+02 16 4. .00 3 .84 0. 3200E+02 17 4 .00 3 .84 0. 3400E+02 18 4. .00 3 .84 0. 3200E+02 19 4. ,00 3, .84 0. 2740E+02 20 4. .00 3 .84 0. 1560E+02 21 6. ,00 5 .77 0. 5280E+02 22 6. ,00 5, .77 0. 1676E+03 23 6. .00 5 .77 0. 1632E+03 24 6, ,00 5, .77 0. 2328E+03 25 6. .00 5, .77 0. 1860E+03 26 6, ,00 5, .77 0. 1650E+03 27 6. ,00 5. .77 0. 1350E+03 28 6, .00 5 .77 0. 1200E+03 29 6. ,00 5, .77 0. 1050E+03 30 6. ,00 5 .77 0. 1110E+03 31 6. ,00 5, .77 0. 1320E+03 32 6. ,00 5, ,77 0. 1470E+03 FIBRE/SYSTEM: 3.3 mm SPECTRA 900 i n 19% E t h a n o l / W a t e r F i b r e l e n g t h : 3.34 mm; F i b r e d i a m e t e r : 0.0380 mm; A= 87. F i b r e d e n s i t y : 939 kg/m**3; S o l u t i o n d e n s i t y : 939 kg/m** Water R e t e n t i o n V a l u e (WRV): 0.010 kg/kg Cm Bulk Den. Cv Y * (%) (kg/m**3) (%) (N/m**2) 1 0 .97 0 .98 0 .7797E+00 2 0 .97 0 .98 0 .9153E+00 3 0 .97 0 .98 0, .6815E+00 4 0 .97 0 .98 0 6628E+00 5 0 .97 0 .98 0, ,6628E+00 6 0 .97 0 .98 0, 5261E+00 7 0 .97 0 .98 0. 6932E+00 8 0 .97 0 .98 0. 7248E+00 9 0 .97 0 .98 0. 6862E+00 10 0 .97 0 .98 0, ,6815E+00 11 1, .50 1 .51 0. 2801E+01 12 1 .50 1 .51 0. 2782E+01 13 1, ,50 1 .51 0. 3098E+01 14 1 .50 1 .51 0. 2315E+01 15 1, 50 1 .51 0. 1917E+01 16 1 , 50 1, .51 0. 2759E+01 17 1, ,50 1, .51 0. 2408E+01 18 1 , 50 1, .51 0. 2981E+01 19 1 . ,50 1, .51 0. 2420E+01 20 1. 50 1, ,51 0. 2303E+01 21 2. 00 2. ,02 0. 4255E+01 22 2. ,00 2, ,02 0. 4033E+01 23 2. 00 2. ,02 0. 4056E+01 24 2. 00 2. 02 0. 4033E+01 25 2. 00 2. ,02 0. 3799E+01 26 2. 00 2. ,02 0. 3086E+01 27 2. 00 2. ,02 0. 3449E+01 28 2. 00 2. ,02 0. 4150E+01 29 2. 00 2. ,02 0. 6628E+01 30 2. 00 2, .02 0. 1181E+02 31 2. ,00 2, ,02 0. 3336E+01 32 2. 00 2, ,02 0. 2183E+01 33 2. 00 2, .02 0. 1968E+01 34 2. 00 2, .02 0. 2343E+01 35 2. 00 2, 02 0. 2090E+01 36 2. 00 2 .02 0. 1996E+01 37 2. 00 2, .02 0. 2024E+01 38 2. ,00 2, .02 0. 1940E+01 39 2. ,00 2, .02 0. 2090E+01 40 2. 00 2, 02 0. 1377E+01 FIERE/SYSTEM: 3.3 mm SPECTRA 900 i n 19% Ethanol/Water ( c o n t i n u e d ) FIBRE/SYSTEM: 3.3 mm SPECTRA 900 i n 19% Ethanol/Wati ( c o n t inued) Cm B u l k Den. Cv Y H (%) (kq/m**3) (%) (N/m**2) 41 3.00 3.03 0 . 4535E+02 42 3.00 3.03 0 .3795E+02 43 3.00 3.03 0 .2033E+02 44 3.00 3.03 0. .2015E+02 45 3.00 3.03 0 .2577E+02 4G 3.00 3.03 0 •2277E+02 47 3.00 3.03 0. .1780E+02 48 3.00 3.03 0 .1874E+02 49 3.00 3.03 0 .2624E+02 50 3.00 3.03 0. 9370E+01 51 3.00 3.03 0 9370E+01 52 3.00 3.03 0 .1780E+02 53 3.00 3.03 0. .1120E+02 54 3.00 3.03 0, ,1800E+02 55 3.00 3.03 0. 9600E+01 5G 3.00 3.03 0, .1722E+02 57 3.00 3.03 0. ,2442E+02 58 3.00 3.03 0. 3540E+02 59 3.00 3.03 0. 4800E+01 60 3.00 3.03 0. 1020E+02 61 3.00 3.03 0. 1602E+02 62 3.00 3.03 0. .3300E+02 63 3.00 3.03 0. 3642E+02 64 4.00 4.04 0. 1578E+02 65 4.00 4.04 0. 1002E+02 66 4.00 4.04 0. 2622E+02 67 4.00 4.04 0. 6120E+02 68 4.00 4.04 0. 8940E+02 69 4.00 4.04 0. 4038E+02 70 4.00 4.04 0. 2478E+02 71 4.00 4.04 0. 6120E+02 72 4.00 4.04 0. 6480E+02 73 4.00 4.04 0. 9660E+02 74 5.00 5.05 0. 2628E+03 75 5.00 5.05 0. 3390E+03 76 5.00 5.05 0. 1590E+03 77 5.00 5.05 0. 1734E+03 78 5.00 5.05 0. 1878E+03 79 5.00 5.05 0. 1950E+03 80 5.00 5.05 0. 1980E+03 Cm B u l k Den. Cv Y £ (%) (kg/m»*3) (%) (N/m**2) 81 5 .00 5 .05 0 .1512E+03 82 5 .00 5 .05 0 .1248E+03 83 5 .00 5 .05 0 .69G0E+02 84 5 .00 5 .05 0 .1380E+03 85 5 .00 5 .05 0 .1080E+03 86 5 .00 5 .05 0, ,6300E+02 87 5 .00 5 .05 0 5400E+02 88 5 .00 5 .05 0 ,1260E+03 89 5 .00 5 .05 0. ,1344E+03 90 5 .00 5 .05 0, ,1290E+03 91 5 .00 5 .05 0, 6960E+02 92 5 .00 5 .05 0. 8460E+02 93 5 .00 5 .05 0. 6600E+02 94 . 5 .00 5 .05 0. 8280E+02 95 5 .00 5 .05 0. 3120E+03 96 5 .00 5 .05 0. 1818E+03 97 5 .00 5 .05 0. 2886E+03 98 5 .00 5 .05 0. 1020E+03 99 5 .00 5 .05 0. 2310E+03 100 5. .00 5, .05 0. 1572E+03 101 5. .00 5. .05 0. 1020E+03 102 5. .00 5. .05 0. 1770E+03 103 5. ,00 5. .05 0. 1488E+03 104 5. .00 5. .05 0. 6300E+02 105 5. .00 5. .05 0. 7920E+02 106 5. ,00 5. .05 0. 7200E+02 107 5. 00 5. 05 0. 1116E+03 108 5. 00 5. .05 0. 2670E+03 109 5. 00 5. 05 0. 1650E+03 110 5. 00 5. 05 0. 1830E+03 111 5. 00 5. 05 0. 1536E+03 112 5. 00 5. 05 0. 8400E+02 113 5. 00 5. 05 0. 1998E+03 114 5. 00 5. 05 0. 1764E+03 115 7. 00 7. 07 0. 9555E+03 116 7. 00 7. 07 0. 1152E+04 FIBRE/SYSTEM: 6.2 mm SPECTRA 900 i n 19% Ethanol/Water F i b r e l e n g t h : 6.15 mm; F i b r e d i a m e t e r : 0.0380 mm; A= 162.0 F i b r e d e n s i t y : 939 kg/m**3; S o l u t i o n d e n s i t y : 939 kg/m**3 Water R e t e n t i o n V a l u e (WRV): 0.010 kg/kg FIBRE/SYSTEM: 6.2 mm SPECTRA 900 In 19% E t h a n o l / W a t e r ( c o n t i n u e d ) Cm B u l k Den. Cv Y It (%) (kq/m**3) (%) (N/m**2) Cm Bulk Den. Cv Y H (%) (kq/m**3) (%) (N/m**2) 1 0.50 0.50 0. 5062E+00 2 0.50 0.50 0 .5646E+00 41 1 .00 1 .01 0 .5434E+01 3 0.50 0.50 0 .3121E+00 42 1 .00 1 .01 0 .1818E+02 4 0.50 0.50 0. ,1952E+00 43 1 .00 1 .01 0 .9211E+01 5 0.50 0.50 0 .9700E-01 44 1 .00 1 .01 0 .8180E+01 6 0.50 0.50 0. .1014E+01 45 1 .00 1 .01 0 .4057E+01 7 0.50 0.50 0. ,1952E+00 46 1 .50 1 .51 0, .6559E+01 8 0.50 0.50 0. 3860E-01 47 1 .50 1 .51 0 .7374E+01 9 0.50 0.50 0. .6430E+00 48 1 .50 1 .51 0 6718E+01 10 0.50 0.50 0. 7830E-01 49 1. .50 1. .51 0, 9557E+01 11 0.50 0.50 0. 3507E+00 50 1. .50 1. .51 0, .1312E+02 12 0.50 0.50 0. 5850E-01 51 1 .50 1 ,51 0, .1483E+02 13 0.50 0.50 0. 2923E+00 52 1 . ,50 1 .51 0, 2343E+02 14 0.50 0.50 0. 1754E+00 53 1 .50 1. ,51 0. 8433E+01 15 0.50 0.50 0. .4092E+00 54 1. .50 1. .51 0, 9839E+01 16 0.50 0.50 0. .1754E+00 55 1 . 50 1. .51 0. 1359E+02 17 0.50 0.50 0. ,4676E+00 56 1 .50 1 .51 0. .7000E+01 18 0.50 0.50 0. 5261E+00 57 2. .00 2. .02 0 .4123E+02 19 0.50 0.50 0. .2689E+00 58 2 .00 2 .02 0 .4835E+02 20 0.50 0.50 0, ,4092E+00 59 2 .00 2 .02 0. .8582E+02 21 0.50 0.50 0, .2923E+00 60 2 .00 2 .02 0 3579E+02 22 0.50 0.50 0. .4325E+00 61 2 .00 2 .02 0. .4067E+02 23 0.50 0.50 0. 3706E+00 62 2 .00 2 .02 0 .4854E+02 24 0.50 0.50 0. .4676E+00 63 2 .00 2 .02 0. 3889E+02 25 0.50 0.50 0, 3238E+00 64 2 .00 2 .02 0. .2680E+02 26 0.50 0.50 0. .1169E+00 65 2 .00 2 .02 0. .5416E+02 27 0.50 0.50 0. 9350E-01 66 2, .00 2 .02 0. . 5884E+02 28 0.50 0.50 0. .1555E+00 67 2. .00 2 .02 0. 2202E+02 29 0.50 0.50 0. ,4096E+00 68 2 .00 2 .02 0. .3600E+02 30 0.50 0.50 0. .3507E+00 69 2. .00 2 .02 0. .3780E+02 31 0.50 0.50 0. 4512E+00 70 2. .00 2 .02 0. .3582E+02 32 0.50 0.50 0. 4676E+00 71 2 .00 2 .02 0. .1920E+02 33 0.50 0.50 0. ,2724E+00 72 2 .00 2 .02 0. . 3000E+02 34 1 .00 1 .01 0, 9651E+01 73 2 .00 2 .02 0. 2280E+02 35 1 .00 1.01 0. ,1752E+01 74 2 .00 2 .02 0. .2478E+02 36 1 .00 1.01 0 .5622E+01 75 2 .00 2 .02 0 .2802E+02 37 1 .00 1 .01 0 .5462E+01 76 2 .00 2 .02 0 .3378E+02 38 1 .00 1 .01 0 .4188E+01 77 2 .00 2 .02 0 . 3000E+02 39 1 .00 1.01 0 .2183E+01 78 2 .00 2 .02 0 .2502E+02 40 1 .00 1.01 0 .5247E+01 79 80 3 3 .00 .00 3 3 .03 .03 0 0 .3300E+02 .7602E+02 ft ft ft C O FIBRE/SYSTEM: 6.2 mm SPECTRA 900 In 19% Ethano1/wat ( c o n t i n u e d ) Cm Bulk Den. Cv Y * it) (kg/m**3) (%) (N/m**2) 81 3 .00 3 .03 0 .5502E+02 82 3 .00 3 .03 0, .2400E+02 83 3 .00 3 .03 0. 6150E+02 84 3 .00 3 .03 0 .4800E+02 85 3 .00 3 .03 0 .1896E+02 86 3 .00 3 .03 0, .4998E+02 87 3 .00 3 .03 0. .4398E+02 88 3 .00 3 .03 0. .4200E+02 89 3 .00 3 .03 0 ,1080E+03 90 3 .00 3 .03 0, ,5880E+02 91 3 .00 3 .03 0. 6300E+02 92 3 .00 3 .03 0. 4482E+02 93 3 .00 3. ,03 0. 5598E+02 94 3 .00 3 .03 0. 5202E+02 95 3 .00 3 ,03 0. 5676E+02 96 4, .00 4. .04 0. 1284E+03 97 4. .00 4. ,04 0. 4380E+02 98 4. .00 4. .04 0. 2016E+03 99 4. .00 4. ,04 0. 1560E+03 100 4. .00 4. .04 0. 1380E+03 101 4. 00 4. 04 0. 3270E+03 102 4. 00 4. 04 0. 4800E+02 103 4. .00 4, ,04 0. 1380E+03 104 4. 00 4. 04 0. 1500E+03 105 4. 00 4. 04 0. 1440E+03 106 4. 00 4. 04 0. 1650E+03 TABLE E , 1 5 : LINEAR REGRESSION RESULTS: Mass C o n c e n t r a t i o n v s . Y i e l d S t r e s s P U L P / F I B R E / S Y S T E M I D E N T I F I C A T I O N MASS CONCENTRATION RANGE USED (%) NUMBER o f DATA POINTS CONSTANT EXPONENTIAL r ' a 9 5 % CONFIDENCE INTERVAL b 9 5 % CONFIDENCE INTERVAL NYLON, 3 mm 15 D e n i e r , S u c r o s e 4.0 - 10.0 61 0.338 0. 125 < a < 0.562 3.23 2.84 < b < 3.61 0.822 NYLON, 5 mm 15 D e n i e r , S u c r o s e 1.5 - 10.0 91 0.882 0.666 < a < 1.01 2.92 2.79 < b < 3.06 0.954 NYLON, 5 mm 15 D e n i e r , W a t e r 2.0 - 6.0 32 3.01 1.85 < a < 4.87 1 .99 1.64 < b < 2.34 0.821 NYLON, 7 mm 15 D e n i e r . S u c r o s e 0.5 - 4.0 60 4.59 3.97 < a < 5.31 2. 19 2.03 < b < 2.35 0.925 SBK- 1 0.4 - 5.0 151 8.36 7.70 < a < 9.08 2.79 2.70 < b < 2.88 0.965 SBK- 1 0.4 - 15.1 166 8.39 7.74 < a < 9.09 2.78 2.71 < b < 2.84 0.976 SBK- 1 0.4 - 33.4 186 9.90 8.58 < a < 11 .8 2.31 2.21 < b < 2.41 0.918 SGW- 1 0.8 - 8.0 109 0.873 0.821 < a < 0.928 3.31 3.26 < b < 3.36 0.995 SGW-1 0.8 - 30.8 140 1 . 18 0.985 < a < 1.42 2.99 2.89 < b < 3.08 0.963 SPECTRA 900, 3.3 mm 1.0 - 7.0 1 16 0.471 0.370 < a < 0.600 3.43 3.23 < b < 3.63 0.911 SPECTRA 900, 6.2 mm 1.0 - 4.0 106 2.76 2.40 < a < 3. 18 3.01 2.84 < b < 3. 18 0.919 TMP-1 0.7 - 6.0 92 1 .06 0.976 < a < 1.15 3.51 3.44 < b < 3.59 0.990 TMP-1 0.7 - 9.2 102 1 .39 1.29 < a < 1.51 3.56 3.50 < b < 3.62 0.992 fa fa fa § fa fa fa fa 2 to Oi Oi TABLE E,16: MULTIPLE LINEAR REGRESSION RESULTS: SUSPENSION a n d FIBRE PROPERTIES v s . YIEL D STRESS SYSTEM I D E N T I F I C A T I O N MASS CONC. RANGE USED (%) No. o f DATA POINTS OUTLIER PROB. REJEC T . In CONST Cv E A r» a SD.ERR. b SD.ERR. c SD.ERR. d SD.ERR. SBK,SGW.TMP A l l D a t a 0.4 - 30.8 428 - 1 .44 1 .010 3.04 0.0249 -0.152 0.0344 0.237 0.097 0.973 SBK,SGW.TMP 0.4 - 30.8 406 0.05 1 .40 0.835 3. 10 0.0217 -0.168 0.0285 0.316 0.080 0.981 SBK,SGW,TMP D a t a <10% Cm 0.4 - 10.0 363 - 0.481 0.858 3.13 0.0277 -0.154 0.0293 0. 472 0.0843 0.973 SBK,SGW.TMP D a t a <10% Cm 0.4 - 10.0 342 0.05 0.883 0.714 3. 18 0.0236 -0.174 0.0244 0.452 0.0698 0.982 NYLON A l l D a t a 1 . 5 - 10.0 286 - -18.3 0.818 2.93 0.0793 - - 3.79 0.161 0.828 NYLON 1 . 5 - 10.0 271 0.05 -16.0 0.708 2.73 0.0675 - - 3.38 0. 138 0.860 PULP/NYLON A l l D a t a 0.4 - 30.8 714 - 1 .38 0.605 2.76 0.0447 -0.190 0.0250 0.521 0.0630 0.848 PULP/NYLON 0.4 - 30.8 677 0.05 -0.261 0.384 2.84 0.0284 -0.098 0.0160 0.488 0.0397 0.939 SPECTRA A l l D a t a 0.5 - 7.0 221 - -11.0 0.820 3. 16 0.0665 - - 2.34 0. 167 0.917 SPECTRA 0.5 - 7.0 209 0.05 -11.0 0.709 3. 15 0.0579 - - 2.36 0. 144 0.939 SPECTRA/NYLON A l l D a t a 0.5 - 10.0 508 - -20.5 0.836 3.04 0.0569 0. 189 0.0223 3.37 0. 125 0.859 SPECTRA/NYLON 0.5 - 10.0 474 0.05 -17.6 0.724 2.89 0.0477 0. 157 0.0184 2.95 0. 106 0.899 APPENDIX E. YIELD DATA CN CO C- cn 01 to 00 tn u> T CO CO 0] 0 0) 00 01 b b b b b b or in 0 in CD 0: 00 CM ID r~ Ul CO CO in CO 1 1 O 0 O 0 0 00 b b b b 0 01 , - 0 CM t - <* CD TJ 1 1 CO 00 l> ID b b b b CC <o cc CM LU CO CO 0 O 1 1 1 1 0 00 b b Ul O O 0 in 1 1 • 1 b b cc 0 CM u> 0) cc tn <3> 10 CM 00 ID UJ O CO CM CM CO CM O O 0 0 O 0 00 b b b b b b > u CN CO ^_ in in CO 00 in O O r~ co £1 CO CO CO CO CM CM cc cc 0 in r~ CD 00 00 Ul t~ in r- •"I ID • CO CO CM r - 0 00 00 b b b b b b Z t_J o O 00 CM 01 ID c CD co CM CO r— •t 0 co 1 CO CO 1 CO 1 CM cc Ul • r— in in in M CO CJ 0 O 0 J O i u 1 1 r - CC "3 b b 1 b 23 O- ui O cc <*- 00 O < H-!•» cc 0 CO CD H- Z 00 t- in O CO 0) • < f - i T - -^ to ID 01 00 OOO z o. • 0 O O 00 00 00 CO O Ul Z tn b t- b b b b O -j CO CO CO CO 0 f—, 1 Ul sS 1 1 1 1 1 U I O - r~ 00 z 0 01 < < S- CC CM b b b b O Z O \ 1—1 z z < < r - 0 0 cc cc -v. \ < _ l _ i r - 1- z Z CJ >- > 0 0 0 O *-t z z Ul (0 LU _ i CO _ i u_ «t < a a > < +J > < £ •-> E CC E CC 00 <o 00 Z cc CO Z cc Ul H- E r- E l— \ 0 \ \ 1- 0 \ r -r - Z O CJ 0. CL Cv CJ Cv O 00 0 J O ui O OJ _ i — _l _ l UJ -1 Ul >- 0 - 0- • Q. 3 — 0 a O CL 00 CO 00 CO 00 a. < a a 00 < CL OI A p p e n d i x F D y n a m i c Test D a t a Table F. l specifies the conditions under which the dynamic tests were conducted. Each test is identified by a sequential test reference number (PFD.xxx) , the pulp type, mass concentration and bulk density. Often the standard deviation of the pulp mass concen-tration is given. The test conditions recorded include the housing and rotor used for the test. These are given by a code, i.e. P F 2 / P F H 1 identifies the wide-gap configuration of the standard 100 mm rotor and 220 mm housing. Specifications for all rotors and housings can be found in Tables A . l and A.2. The maximum speed target in the test, and the control program (time to reach the maximum speed, time at maximum speed and deceleration time) are recorded. In most cases these correspond to the standard test run: linear acceleration to 5000 rpm in 10 seconds, a 5 second steady-state period at 5000 rpm, linear deceleration to rest in a further 10 seconds. The friction on the fluidizer shaft depended on the pressure maintained inside the cooling seal and was kept between 410 and 480 kPa. Finally, comments or observations noted during the test are recorded. Tables F.2 through F.5 specify the power dissipation per unit volume, e, at the point of flow transition in the pidp fluidizer for semi-bleached kraft, stone groundwood and themomechanical pulps. These tables include the pulp mass and volume concentration, the bulk density, test reference number, and the fluidizer rotor and housing used in the test. The rpm and torque at the onset of flow transition in acceleration, and the power 269 APPENDIX F. DYNAMIC TEST DATA 270 dissipation for the transition in acceleration and deceleration are recorded. The values of torque and rotational speed at the onset of flow transition were ob-tained as follows. The interval that elapsed between the first observed rotor movement and the flow transition was timed (often multiple measurements were made) and used to look up the torque and rotational speed in the data file (where the elapsed time, torque, rotational speed and suspension temperature had been recorded at 0.04 second intervals). The power dissipated per unit volume was calculated from this data. If a confidence interval is specified it represents the standard deviation between multiple determinations. Some error was introduced by timing variations and the subjective in-terpretation of when the housing had become completely involved in the post-transition flow pattern. For tests made with the narrow-gap configuration, the torque would in-crease dramatically at the flow transition point (e.g. from 10 —> 35 N-m in approx-imately 0.2 seconds). Any small timing error would therefore result in a large error when calculating the power at the flow transition. In this case, a second set of deter-minations was made using the sudden change in torque as the criteria for the onset of flow transition. This was not possible in those instances where a sudden torque change did not occur, i.e. for low consistency (< 4% Cm) suspensions, or for most tests made in the wide-gap configuration. APPENDIX F. DYNAMIC TEST DATA CD c o a N i — 3 a 0 c i — c (0 (0 c c 0 CO +< TJ - OJ c TJ N TJ -0 TJ TJ ~-0) C 3 N +* <-H-TJ 3 10 3 TJ •-l- »— 0) •-Z 3 LU O <t-E > 10 E •— CL ** O c 01 O CJ o or z DC — _l UJ CO o O o O O o o O o o o O o O o o O o O < 1- L t- r-LU < Jt TT TT TT TT TT Tf TT TT TT Tf TT TT TT TT TT TT LO 3 w or o — LU If) , o O o o O o o o o O o o o o o o O o o LU Q TJ E >>. C •! \ \ \ \ \ \ \ \ \ \ \ \ \ \ « (- 0 tn in in tn " in in in in tn in in tn in in in in in tn in 1- < o \ \ \ \ \ \ \ \ \ \ \ \ \ \ •v. — 0) O o O o O O o o o o O o o O o o O o O O 0) (- w or o j-o o o o o O o o o o o o o o o o O o o or a o o o o o o o o o o o o o o o o o o o UJ o o o o o o <5 o o o o o o o o o o o o X UJ E tn in in in tn tn in in in in in in in in in in in in in < o. a E to C CM CM CM CM CM CM CM CM CM CM CM CM CM CM CM CM CM CM •6 (9 X I X X X I ' X X X I I X I X X X X X X z or <-• a a. CL CL a. CL ' CL - CL a. CL CL CL CL CL CL CL CL OL CL O to o \ \ \ \ \ \ \ \ — — \ \ \ \ •s. \ \ — l - 3 UJ CO CO CO CO CO CO CO CO co CO CO CO CO CO CO CO CO CO CO O O to : or I 3 CL a 0. CL CL CL CL a CL a. CL CL CL CL CL a CL CL a CO > » o o D— * E T- T- O * to \ o O J Z DI O 3 LU JC T— T— co a —< z ~ 5t« s« se >« ^ s« s* o o O o o O o o o O o o o o o — E K CJ CM CM CM TT TT TT CO co CO CM CM CL •— T -I—I eS or L. i- o a. 01 1 l i 1 1 1 1 I 1 1 i 1 1 1 LO LO 1 L. c •f ir ir LU UJ 3 a (0 CO CO CO 00 CO CO 00 CO off 00 CO LO m as h O Q. < 3 < 3 3 3 3 < . 3 3 3 3 3 3 3 3 3 3 3 0 CM CO TT tn UJ r- CO 0) o CM CO TT in (0 l~ CO 01 z o o o o O O O O o T- T- T- T- T- T- T- T~ T - ~-o O o o O O O O o o o o o o o o o O o 1-to a O Q o o o O a a a o o o a o a a Q a LU U- u. LL U- u. u. u. u_ LL LL u_ u. LL LL LL u. LL LL LL 1- a a CL CL CL CL a. a CL a CL CL CL CL CL CL a a CL TABLE F . I : CONDITIONS OF DYNAMIC TESTS CONDUCTED WITH THE PULP F L U I D I Z E R ( c o n t i n u e d ) TEST No. TEST D E S C R I P T I O N PULP & Cm (%) BULK DENSITY (kg/m**3) ROTOR & HOUSING USED MAX ROTOR SPEED rpm TIME (TO/AT/DECR.) ( s e c o n d s ) SEAL WATER ( k P a ) COMMENTS PFD.021 UBK-1, 1.0% PF3/PFH2 5000 10/5/10 410 V i d e o t a p e d . PFD.022 UBK-1, 8.0% PF3/PFH2 5000 10/5/10 410 V i d e o t a p e d . N o t c o m p l e t l y f l u l d l z e d . P FD.023 UBK-1, 8.0% PF3/PFH2 5000 10/5/10 410 R e p a c k e d w i t h a d d i t i o n a l p u l p . N o t c o m p l e a t l y f l u l d l z e d . PFD.024 UBK-1, 2.0% PF3/PFH2 5000 10/5/10 410 PFD.025 UBK-1,12.0% PF2/PFH2 5000 10/5/10 410 "dump" m l o a d . PFD.026 W a t e r 1000 PF3/PFH2 3 0 0 0 5/0/5 410 C h e c k f o r h y s t e r e s i s . PFD.027 W a t e r 1000 PF3/PFH2 3000 10/0/10 410 C h e c k f o r h y s t e r e s i s . PFD.028 W a t e r 1000 PF3/PFH2 3000 20/0/20 410 C h e c k f o r h y s t e r e s i s . P F 0 . 0 2 9 A i r 1 .00 PF2/PFH1 5000 5/10/5 410-480 F i b r e b r e a k a g e t e s t s . P F D.030 UBK-1, 6.0% 940 PF2/PFH1 5000 5/10/5 4 1 0 - 4 8 0 PFD.031 UBK-1, 6.0% 999 PF2/PFH1 5000 5/10/5 4 1 0 - 4 8 0 C o m p l e t e m o t i o n a c h i e v e d . PFD.032 UBK-1, 6.0% 1030 PF2/PFH1 5000 5/10/5 4 1 0 - 4 8 0 R a d i a l m o t i o n o b s e r v e d . PFD.033 UBK-1, 6.0% 1040 PF2/PFH1 5000 5/10/5 4 1 0 - 4 8 0 PFD.034 UBK-1, 6.0% 1040 PF2/PFH1 5000 5/15/5 4 1 0 - 4 8 0 PFD.035 UBK-1, 6.0% 1040 PF2/PFH1 5000 5/15/5 4 1 0 - 4 8 0 PFD.036 UBK-1, 6.0% 1040 PF2/PFH1 5000 5/15/5 410-480 PFD.037 UBK-1. 6.0% 1040 PF2/PFH1 5000 5/15/5 410-480 F i b r e s i z e a n a l y s e d b y K a j a n n l F S - 1 0 0 s howed no r e d u c t i o n 1n f i b r e l e n g t h b e t w e e n t e s t s . PFD.038 SBK-2, 9.6+0.6% 982 PF2/PFH1 5000 10/5/0 410 T r i a l s t o show i f r e s u l t s a r e I n d e p e n d e n t o f a c c e l e r a t i o n r a t e . P FD.039 SBK-2. 9.4+0.9% 984 PF2/PFH1 5000 20/5/0 4 1 0 PFD.040 SBK-2, 9.2+0.4% 980 PF2/PFH1 5000 30/5/0 410 5u fa fa fa § fa 3 to fa 12 2 to C O TABLE F • 1 : CONDITIONS OF DYNAMIC TESTS CONDUCTED WITH THE PULP FLU I D I Z E R ( c o n t i n u e d ) T E S T No. TEST D E S C R I P T I O N PULP & Cm (%) BULK DENSITY (kg/m**3) ROTOR & HOUSING USED MAX ROTOR SPEED rpm TIME (TO/AT/DECR. ) ( s e c o n d s ) SEAL WATER ( k P a ) COMMENTS PFD.041 W a t e r 1000 PF2/PFH1 5000 30/5/0 410 PFD.042 A 1 r 1 .0 PF2/PFH1 5000 30/5/0 410 PFD.043 S B K - 2 . 1 0 . 0 % 1020 PF2/PFH1 5000 10/5/0 410 P F 0 . 0 4 4 S B K - 2 , 1 0 . 0 % 1030 PF2/PFH1 5 0 0 0 10/5/0 410 PFD.045 S B K - 2 . 1 0 . 0 % 1030 PF2/PFH1 5000 10/5/0 410 PFD.046 A i r 1 .0 PF2/PFH1 5000 10/5/10 4 10 PFD.047 W a t e r 1000 PF2/PFH1 5000 10/5/10 410 PFD.048 SBK-2, 2.0% 1010 PF2/PFH1 5000 10/5/10 410 PFD.049 SBK-2, 2.0% 1000 PF2/PFH1 5000 10/5/10 410 PFD.050 SBK-2, 4.0% 1000 PF2/PFH1 5 0 0 0 10/5/10 410 PFD.051 SBK-2, 4.0% 1000 PF2/PFH1 5000 10/5/10 410 PFD.052 SBK-2, 6.0% 992 PF2/PFH1 5000 10/5/10 410 PFD.053 SBK-2. 8.0% 957 PF2/PFH1 5000 10/5/10 410 PFD.054 SBK-2. 8.0% 998 PF2/PFH1 5000 10/5/10 410 PFD.055 SBK-2. 9 . 7 ± 0 . 3 % 979 PF2/PFH1 5000 10/5/10 4 1 0 PFD.056 SBK-2. 9.7+0.3% 1020 PF2/PFH1 5 0 0 0 10/5/10 410 PFD.057 S B K - 2 , 1 3 . 1 ± 0 . 5 % 952 PF2/PFH1 5000 10/5/10 410 PFD.058 S B K - 2 , 1 3 . 1 ± 0 . 5 % 1020 PF2/PFH1 5000 10/5/10 410 PFD.059 SBK-2,13.1+0.5% 1050 PF2/PFH1 5000 10/5/10 410 PFD.060 SBK-2,14.9+0.4% 952 PF2/PFH1 5000 10/5/10 410 TABLE F , 1 : CONDITIONS OF DYNAMIC TESTS CONDUCTED WITH THE PULP FLU I D I Z E R ( c o n t i n u e d ) TEST No. TEST D E S C R I P T I O N PULP ft Cm (%) BULK DENSITY (kg/m**3) ROTOR 6 HOUSING USED MAX ROTOR SPEED rpm TIME (TO/AT/DECR.) ( s e c o n d s ) SEAL WATER ( k P a ) COMMENTS PFD.061 SBK-2,14 . 9 ± 0 . 4 % 1010 PF2/PFH1 5006 10/5/10 410 PFD.062 SBK-2, 14.9+0.4% 1040 PF2/PFH1 5000 10/5/10 410 PFD.063 S B K - 2 . 1 6 . 0 % 921 PF2/PFH1 5000 10/5/10 410 PFD.064 SBK-2,16.0% 957 PF2/PFH1 5000 10/5/10 410 PFD.065 S B K - 2 , 1 6 . 0 % 985 PF2/PFH1 5000 10/5/10 410 PFD.066 A 1 r 1 .0 PF2/PFH1 5000 10/5/10 410 PFD.067 W a t e r 1000 PF2/PFH1 5000 10/5/10 410 PFD.068 W a t e r 1000 PF2/PFH1 5000 10/5/10 410 PFD.069 S G W - 1 . 1 0 . 0 ± 0 . 1 % 998 PF2/PFH1 5000 10/5/10 410 PFD.070 SGW-1,10.010.1% 998 PF2/PFH1 5000 10/5/10 410 PFD.071 TMP-1. 9 . 8 ± 0 . 8 % 1010 PF2/PFH1 5000 10/5/10 410 PFD.072 TMP-1, 9.8+0.8% 1010 PF2/PFH1 5000 10/5/10 410 PFD.073 A 1 r 1 .0 PF3/PFH1 5000 10/5/10 410 PFD.074 W a t e r 1000 PF3/PFH1 5000 10/5/10 410 PFD.075 S B K - 2 , 1 0 . 0 ± 0 . 5 % 967 PF3/PFH1 5000 10/5/10 410 PFD.076 SBK-2,10.0+0.5% 997 PF3/PFH1 5000 10/5/10 410 PFD.077 A 1 r 1 .0 PF4/PFH1 5000 10/5/10 410 New 100 mm r o t o r . PFD.078 W a t e r 1000 PF4/PFH1 5000 10/5/10 410 PFD.079 S B K - 2 . 1 0 . 0 ± 0 . 5 % 962 PF4/PFH1 5000 10/5/10 410 PFD.080 S8K-2.10.0+0.5% 1002 PF4/PFH1 5000 10/5/10 410 fa 8. § fa fa fa fa Co fa fa 2 CO —J rF-TABLE F . 1 : CONDITIONS OF DYNAMIC TESTS CONDUCTED WITH THE PULP FLU I D I Z E R ( c o n t i n u e d ) TEST No. TEST D E S C R I P T I O N PULP 8. Cm (%) BULK DENSITY (kg/m**3) ROTOR a HOUSING USED MAX ROTOR SPEED ' rpm TIME (TO/AT/DECR.) ( s e c o n d s ) SEAL WATER ( k P a ) COMMENTS PFD.081 SGW-1, 6.1+0.3% 1010 PF2/PFH1 5000 10/5/10 410 PFD.082 SGW-1. 6 . 1 ± 0 . 3 % 1010 PF2/PFH1 5000 10/5/10 410 PFD.083 SGW-1. 9 . 0 ± 0 . 7 % 1000 PF2/PFH1 5000 10/5/10 410 PFD.084 SGW-1, 9 . 0 ± 0 . 7 % 1000 PF2/PFH1 5000 10/5/10 410 PFD.085 SBK-2.12.6+0.9% 969 PF4/PFH1 5000 10/5/10 410 PFD.086 S B K - 2 , 1 2 . 6 ± 0 . 9 % 1010 PF4/PFH1 5000 10/5/10 410 PFD.087 SBK-2, 9 . 7 ± 0 . 3 % 1010 PF2/PFH1 5000 10/5/10 410 B l a c k d y e d f i b r e p l a c e d a t b a c k o f c h a m b e r . PFD .088 SBK-2, 9 . 7 ± 0 . 3 % 970 PF2/PFH1 5000 10/5/10 410 B l a c k d y e I n j e c t e d a t e a c h r o t o r v a n e b e f o r e t e s t . PFD.089 SBK-2, 9 . 7 ± 0 . 3 % 1000 PF2/PFH1 5000 10/5/10 410 1mm r e d n y l o n f l o e p l a c e d a t l o w e r r e a r o f f l u i d i z e r c h a m b e r . PFD.090 SBK-2, 6 . 4 ± 0 . 3 % 1010 PF2/PFH1 5000 10/5/10 410 PFD.091 SBK-2, 6 . 4 ± 0 . 3 % 1030 PF2/PFH1 5000 10/15/10 410 PFD.092 SBK-2, 6.4+0.3% 1040 PF2/PFH1 5000 10/30/10 410 PFD.093 S B K - 2 , 1 0 . 0 ± 0 . 1 % 970 PF2/PFH1 5000 10/15/10 410 Hycam 9 300 p p s . B l a c k d y e I n j e c t e d a t e a c h r o t o r v a n e . PFD.094 SBK-2. 9 . 7 ± 0 . 5 % 960 PF2/PFH1 5000 10/5/10 410 E n e r g y I n p u t t r i a l s . No f l o w t r a n s i t i o n . PFD.095 SBK-2, 9.7+0.5% 1000 PF2/PFH1 5000 10/20/10 410 F l o w t r a n s i t i o n . PFD.096 SBK-2, 9 . 7 ± 0 . 5 % 1020 PF2/PFH1 5000 10/40/10 410 PFD.097 A 1 r 1.0 PF2/PFH2 5000 10/5/10 410 PFD.098 W a t e r 1000 PF2/PFH2 5000 10/5/10 410 PFD.099 SBK-2. 2% 1010 PF2/PFH2 5000 10/5/10 410 Max. temp. • 4 3 . 4 ° C TABLE F . I : CONDITIONS OF DYNAMIC TESTS CONDUCTED WITH THE PULP F L U I D I 2 E R ( c o n t i n u e d ) TEST No. TEST D E S C R I P T I O N PULP & Cm (%) BULK DENSITY (kg/m**3) ROTOR & HOUSING USED MAX ROTOR SPEED rpm TIME (TO/AT/DECR.) ( s e c o n d s ) SEAL WATER ( k P a ) COMMENTS PFD.100 SBK-2, 4% 1030 PF2/PFH2 5000 10/5/10 410 Max. temp. = 4 3 . 3 ° C PFD.101 SBK-2, 6.9+0.3% 900 PF2/PFH2 5000 10/5/10 4 1 0 Max. temp. = 4 7 . 2 ° C PFD.102 SBK-2, 8.3+0.4% 970 PF2/PFH2 5000 10/5/10 410 Max. temp. = 4 8 . 2 ° C PFD.103 SBK-2, 9 . 2 ± 0 . 4 % 950 PF2/PFH2 5000 10/5/10 410 E n e r g y I n p u t t r i a l . Max. temp. » 4 6 . 5 ° C PFD.104 SBK-2, 9.2+0.4% 960 PF2/PFH2 5000 10/15/10 410 Max. temp. = 7 2 . 9 ° C PFD.105 SBK-2, 9.2+0.4% 1010 PF2/PFH2 5000 10/35/10 4 8 0 Max. temp. = 1 1 4 . 7 ° C PFD.106 S B K - 2 , 1 1 . 7 ± 0 . 8 % 960 PF2/PFH2 5000 10/5/10 410 PFD.107 S B K - 2 , 1 1 . 7 ± 0 . 8 % 960 PF2/PFH2 5000 10/5/10 410 PFD.108 SBK-2,13.8+0.2% 970 PF2/PFH2 5000 10/5/10 410 I t t o o k 7 a t t e m p t s t o b r e a k t h e r o t o r f r e e . W e l l d e f i n e d s h e a r p l a n e a n d low power d r a w n . PFD.109 W a t e r 1000 PF2/PFH2 5000 10/5/10 4 1 0 PFD. 1 10 W a t e r 1000 PF2/PFH2 5000 10/5/10 4 1 0 PFD.111 S B K - 2 , 8 . 7 ± 0 . 3 % PF1/PFH2 5000 10/5/10 410 PFD.1 12 W a t e r 1000 PF1/PFH2 5000 10/5/10 410 PFD. 113 SBK-2,8.7+0. 3% PF4/PFH2 5000 10/5/10 4 1 0 PFD. 1 14 W a t e r 1000 PF4/PFH2 5000 10/5/10 410 PFD. 1 15 SBK-2, 1.0+0.1% PF2/PFH1 2000 10/5/10 410 PFD. 1 16 SBK-2, 1 . 0 ± 0 . 1 % PF2/PFH1 2000 10/5/10 4 1 0 PFD . 1 17 SBK-2, 2 . 0 ± 0 . 2 % PF2/PFH1 2000 10/5/10 410 PFD. 1 18 SBK-2, 2 . 0 ± 0 . 2 % PF2/PFH1 2000 10/5/10 450 PFO.1 19 SBK-2, 2.9+0.3% PF2/PFH1 2000 10/5/10 4 1 0 PFD.120 SBK-2, 2 . 9 ± 0 . 3 % PF2/PFH1 2000 10/5/10 4 1 0 3 co 2 2 to O i TABLE F. 1: CONDITIONS OF OYNAMIC TE S T S CONDUCTED WITH THE PULP FLU I D I Z E R ( c o n t i n u e d ) TEST No. TES T D E S C R I P T I O N PULP & Cm (%) BULK DENSITY (kg/m**3) ROTOR & HOUSING USED MAX ROTOR SPEED rpm TIME (TO/AT/DECR.) ( s e c o n d s ) SEAL WATER ( k P a ) COMMENTS PFD.121 SBK-2, 3 . 9 ± 0 . 3 % PF2/PFH1 2000 10/5/10 410 PFD.122 SBK-2. 3 . 9 ± 0 . 3 % PF2/PFH1 2000 10/5/10 410 PFD.123 SBK-2, 10.6+0.9% 1050 PF2/PFH1 5000 10/5/10 410 Hycam ff 300 p p s . D y e d f i b r e . PFD.124 SBK-2,9.98+0.13% 940 PF2/PFH1 5000 10/5/10 410 Hycam ff 300 p p s . D y e d l i q u i d . D i d n o t g o t h r o u g h f l o w t r a n s i t i o n . PFD.125 G I y c e r o l 1250 PF2/PFH1 2500 10/5/10 480 0.0087 k g r e d n y l o n f i b r e a s t r a c e r . ? = 1.4 P a . s ff 2 0 . 0 ° C PFD.12G G l y c e r o l 1250 PF2/PFH1 2500 10/5/10 480 „ = 1.4 P a . s ff 2 0 . 0 ° C PFD.127 G l y c e r o l w i t h g l a s s b e a d . PF2/PFH1 2500 10/5/10 450 „ = 1.5 P a . s ff 2 0 . 0 ° C PFD.128 G l y c e r o l w i t h g l a s s b e a d . PF2/PFH1 2500 10/5/10 460 „ = 1.6 P a . s ff 2 0 . 0 ° C PFD.129 G l y c e r o l 1250 PF2/PFH1 5000 10/5/10 410-450 „ = 1.5 P a . s ff 2 0 . 0 ° C PFD.130 G I y c e r o l 1250 PF2/PFH2 5000 10/5/10 410 „ = 1.5 P a . s ff 2 0 . 0 ° C PFD.131 G l y c e r o l PF2/PFH2 5000 10/5/10 450 PFD.132 G I y c e r o l PF2/PFH2 5000 10/5/10 410 PFD.133 G 1 y c e r o l PF2/PFH2 5000 10/5/10 410 PFD.134 S B K - 4 , 0 . 9 2 ± 0 . 2 9 % 993 PF3/PFH2 5000 10/5/10 450 PFD.135 SBK-4,0.92+0.29% 993 PF3/PFH2 5000 10/5/10 450 PFD.136 S B K - 4 , 4 . 1 7 ± 0 . 1 3 % 983 PF3/PFH2 5000 10/5/10 450 PFD.137 SBK-4,6.11+0.59% 985 PF3/PFH2 5000 10/5/10 450 PFD.138 S B K - 4 , 8 . 6 5 ± 0 . 4 4 % 973 PF3/PFH2 5000 10/5/10 450 PFD.139 SBK-4,8.65+0.44% 1020 PF3/PFH2 5000 10/5/10 480 PFD. 140 S B K - 4 , 9 . 5 2 ± 0 . 2 1 % 919 PF3/PFH2 5000 10/5/10 480 P r o m i n e n t g a s p h a s e . >-fa fa fa fa :i et CO fa S s to TABLE F . 1 : CONDITIONS OF DYNAMIC TESTS CONDUCTED WITH THE PULP FLU I D I Z E R ( c o n t i n u e d ) TEST No. TEST DESCRIPTION PULP & Cm ('/.) BULK DENSITY (kg/m**3) ROTOR & HOUSING USED MAX ROTOR SPEED rpm TIME (TO/AT/DECR.) ( s e c o n d s ) SEAL WATER ( k P a ) COMMENTS PFD. 141 SBK-4,9.52+0.21% 1010 PF3/PFH2 5000 10/5/10 480 PFD.142 A i r 1 .0 PF3/PFH2 5000 10/5/10 480 PFD.143 W a t e r 1000 PF3/PFH2 5000 10/5/10 480 PFD.144 S B K - 4 , 1 . 6 1 ± 0 . 2 1 % 1010 PF3/PFH1 5000 10/5/10 4 5 0 PFD.145 S B K - 4 , 4 . 6 4 ± 0 . 2 2 % 1000 PF3/PFH1 5C00 10/5/10 450 No m o t i o n a t h o u s i n g w a l l . PFD.146 S B K - 4 , 6 . 5 1 ± 0 . 1 6 % 1000 PF3/PFH1 5000 10/5/10 460 PFD.147 SBK-4,8.13+0.10% 1000 PF3/PFH1 5000 10/5/10 480 PFD.148 SBK-4,9.06+0.83% 1000 PF3/PFH1 5000 10/5/10 480 PFD.149 S B K - 4 . 9 . 5 2 ± 0 . 2 1 % 1020 PF3/PFH1 5000 10/5/10 480 PFD.150 A i r 1 .0 PF3/PFH1 5000 10/5/10 4 8 0 PFD.151 W a t e r 1000 PF3/PFH1 5000 10/5/10 4 5 0 PFD.152 G y l c e r o l 1250 PF2/PFH1 5000 20/2/8 480 PFD.153 G l y c e r o l 1250 PF2/PFH1 5000 20/2/8 480 PFD.154 9 0 % G l y c e r o l 1240 PF2/PFH1 5000 20/2/8 480 PFD.155 S B K - 1 , 9 . 5 8 ± 0 . 6 3 % 1030 PF2/PFH1 5000 10/5/10 480 S e q u e n t i a l t e s t s . Max. temp. « 2 3 ° C PFD.156 S B K - 1 , 9 . 5 8 ± 0 . 6 3 % 1030 PF2/PFH1 5000 10/5/10 480 Max. temp. • 3 2 ° C PFD.157 SBK-1,9.58+0.63% 1030 PF2/PFH1 5000 10/5/10 480 Max. temp. • 4 0 ° C PFD.158 S B K - 1 , 9 . 5 8 ± 0 . 6 3 % 1030 PF2/PFH1 5000 10/5/10 480 Max. temp. = 4 8 ° C PFD.159 SBK-1 .9.58+0.63% 1030 PF2/PFH1 5000 10/5/10 480 Max. temp. = 5 6 ° C PFD.160 S B K - 1 , 9 . 5 8 ± 0 . 6 3 % 1030 PF2/PFH1 5000 10/5/10 480 Max. temp. = 6 3 ° C PFD.161 S B K - 1 , 9 . 5 8 1 0 . 6 3 % 1030 PF2/PFH1 5000 10/5/10 480 S u s p e n s i o n c o o l e d t o 2 0 ° C . TABLE F.2: POWER D I S S I P A T E D AT THE POINT OF FLOW TRANSITION: S e m i - b l e a c h e d k r a f t ( S B K - 2 ) STOCK Cm (%) BULK DENSITY (kg/m**3) STOCK Cv (%) TEST REFERENCE ID. HOUSING & ROTOR USED FLOW TRANSITION ( A C C E L ) POWER, W/m**3 ROTATION (rpm) TORQUE (N.m) ACCEL DECEL 1 .0 1 .93 PFD . 115 PF2/PFH1 515 0.6 1.06+0.11 E04 0.0 1 .0 1 .93 PFD. 116 PF2/PFH1 612 0.8 1.49+0.29 E04 0.0 2.0 1010 3.89 PFD.048 PF2/PFH1 883 2.9 8.36+1.79 E04 4 .7218. 17 EOS 2.0 1000 3.85 PFD.049 PF2/PFH1 971 2.6 8.4111.25 E04 0.0 2.0 3.83 PFD.1 17 PF2/PFH1 667 1 .4 2.9610.16 E04 5.7314.96 E02 2.0 3.88 PFD. 1 18 PF2/PFH1 663 1 . 1 2.4310.39 E04 3.0111.10 E03 2.9 5.64 PFD. 1 19 PF2/PFH1 845 2. 1 5.79+0.02 E04 1.0110.38 E04 2.9 5.64 PFD.120 PF2/PFH1 786 2.0 5.0510.57 E04 2.48+0.25 E04 3.9 7.61 PFD.121 PF2/PFH1 1 176 2.8 1.0910.34 E05 7.8810.83 E04 3.9 7.61 PFD.122 PF2/PFH1 1395 2.9 1.3710.05 E05 7.9110.73 E04 4.0 1000 7.71 PFD.050 PF2/PFH1 1266 4.2 1.3410.19 E05 1.2110.21 E05 4.0 1000 7.71 PFD.051 PF2/PFH1 1422 3.4 1.6010.05 E05 5.3310.31 E04 6.0 992 11.4 PFD.052 PF2/PFH1 2888 9.7 9.3211.49 E05 7.22+1.61 E05 6.4 1010 12.5 PFD.090 PF2/PFH1 3204 12.0 1.28+0.14 E06 4.94+0.54 E05 6.4 1030 12.7 PFD.091 PF2/PFH1 3191 13.8 1.4610.24 E06 4.6810.57 E05 6.4 1040 12.8 PFD.092 PF2/PFH1 2726 9.7 8.7710.18 E05 3.0410.33 E05 8.0 957 14 . 8 PFD.053 PF2/PFH1 4661 20.5 3.1810.05 E06 1.6210.09 E06 8.0 998 15.4 PFD.054 PF2/PFH1 3806 17.1 2.1810.56 E06 1.6910.58 E06 fa fa fa ft fa cl CO fa fa S CO co TABLE F.2: POWER D I S S I P A T E D AT THE POINT OF FLOW TRANSITION: Sem1-b1eached k r a f t ( S B K - 2 ) ( c o n t i n u e d ) STOCK Cm (%) BULK DENSITY (kg/m**3) STOCK Cv (%) TEST REFERENCE ID. HOUSING & ROTOR USED FLOW TRANSITION ( A C C E L ) POWER, W/m**3 ROTATION (rpm) TORQUE (N.m) ACCEL DECEL 9.7 1010 18.9 PFD.087 PF2/PFH1 4075 19.7 2.66+0.26 E06 1.5810.66 E06 9.7 970 18. 1 PFD.088 PF2/PFH1 4243 15.9 2.23+0.22 E06 1.2410.03 E06 9.7 1000 18.7 PFD.089 PF2/PFH1 3667 14.6 1 .78+0. 16 E06 9.2410.12 E05 9.7 979 18.3 PFD.055 PF2/PFH1 4834 21.4 3.44+0.18 E06 1.9710.51 E06 9.7 1020 19. 1 PFD.056 , PF2/PFH1 4575 23.4 3.29+0.28 E06 1.8210.18 E06 10. 962 18.5 PFD.079 PF4/PFH1 3494 20.6 2.2310.46 E06 1.5410.36 E06 12 . 1050 24 . 3 PFD.059 PF2/PFH1 4830 31.8 5.10+0.31 E06 4.28+1.05 E06 12.6 969 23.5 PFD.085 PF4/PFH1 4046 25.3 3.15+0.07 E06 1.5510.13 E06 12.6 1010 24.5 PFD.086 PF4/PFH1 4133 27.4 3.49+0.39 E06 1.3310.07 E06 TABLE F.2: POWER D I S S I P A T E D AT THE POINT OF FLOW TRANSITION: S e m i - b i e a c h e d k r a f t ( S B K - 2 ) ( c o n t i n u e d ) ( a ) B a s e d o n o b s e r v a t i o n o f f l o w t r a n s i t i o n . STOCK Cm (%) BULK DENSITY (kg/m**3) STOCK Cv (%) TEST REFERENCE ID . HOUSING & ROTOR USED FLOW TRANSITION ( A C C E L ) POWER. W/m*+3 ROTATION (rpm) TOROUE (N.m) ACCEL DECEL 2.0 1010 3.96 PFD.099 PF2/PFH2 767 1 . 5 1.69+0.4 1 E05 0.0 4.0 1030 8 .08 PFD.100 PF2/PFH2 1069 3 . 2 5 . 0 1 ± 1 . 8 9 E05 3.15+3.48 E04 6.0 9 0 0 10.6 PFD.101 PF2/PFH2 2519 17.3 6.33+1.10 E06 2.45+0.8 1 E06 8.3 9 7 0 15.8 PFD.102 PF2/PFH2 2860 20. 1 8.23+0.61 E06 4.47+0.63 E06 8.7 17 . 1 PFD . 113 PF2/PFH2 3784 18.7 8.0011.40 E06 4.01+0.55 E06 9.2 950 17. 1 PFD.103 PF2/PFH2 3344 33.3 1.6110.02 E07 9. 1211.09 E06 9.2 9 6 0 17.3 PFD.104 PF2/PFH2 2792 17.4 7 .4316.14 E06 4.8510.18 E06 9.2 1010 18.2 PFD.105 PF2/PFH2 3526 28.4 1 .46+0.45 E06 1.2110.09 E06 11.7 9 6 0 22.0 PFD.106 PF2/PFH2 3926 18.5 1.05+0.02 E07 9.31+4.92 E06 11.7 9 6 0 22.0 PFD.107 PF2/PFH2 3567 33.5 1.70+0.05 E07 6.2812.74 E06 TABLE F . 2 : POWER D I S S I P A T E D AT THE POINT OF FLOW TRANSITION: S e m i - b l e a c h e d k r a f t ( S BK-2) ( c o n t i n u e d ) ( b ) B a s e d o n t o r q u e - r o t a t i o n a l s p e e d c u r v e STOCK Cm (%) BULK DENSITY (kg/m**3) STOCK Cv (%) TEST REFERENCE ID. HOUSING & ROTOR USED FLOW TRANSITION ( A C C E L ) POWER, W/m**3 ROTATION (rpm) TORQUE (N.m) ACCEL DECEL 6.0 900 10.6 PFD.101 PF2/PFH2 2321 7.2 2.43 E06 8 . 3 970 15.8 PFD.102 PF2/PFH2 2736 10.4 4.11 E06 8.7 17. 1 PFD. 1 13 PF2/PFH2 3125 11.1 5.00 E06 9 . 2 950 17 . 1 PFD.103 PF2/PFH2 3238 13.2 6.16 E06 9.2 960 17 . 3 PFD.104 PF2/PFH2 3064 12.4 5.48 E06 9.2 1010 18.2 1 PFD.105 PF2/PFH2 3241 13.7 6.40 E06 11.7 9 6 0 22.0 PFD.106 PF2/PFH2 4015 19.8 1 . 15 E07 11.7 960 22.0 PFD.107 PF2/PFH2 3509 16.3 8.27 E06 APPENDIX F. DYNAMIC TEST DATA 283 _J LU o CO o * * £ -or LU 3 O TT TT TT m Tf in in CO TT in in CO in in CD 0. O o o O o O O O O O O o O O O _ l LU LU 1X1 LU UJ LU Ul LU LU cu LU UJ LU LU LU LU CJ TT cn 01 T— 01 t~ oo 01 CO CD CO CM CO CO CO CJ o CM CM CO in CM in CO o to 01 o CD GO 0) < CM CM co CM in CO CO CO l> Ul in t> CO E Z .—* > - o in T- in CO T— 1- ID _J CO r- 01 co TT CD CO in CO -^ o oo CO O LU LU o 3 T- ^~ O O CM CM TT Tf CO 01 TT 01 CO o O < DC '—' . O t-z o (- E a LO c_ z •w < or Z ID T— CM O O CD ~- o O o T— O 0) O t- o O 01 cn tn TT o in CM O O co co o CO O •—< CO CO CO CO o CO O TT o CD CD TT 0) in GO 3 : T- CM CM CM CM CO CM TT CO CM TT O < —1 r-u. o or CM CM CM CM CM CM o or X X I X X X I I X X X X X X X Z o •-• f- CL CL CL CL CL CL CL CL CL CL CL CL CL a CL LO O D \ \ \ \ \ \ • 1— \ \ — \ \ - V \ — 3 or LU CO CO CM CO CO CM CO CO CM CO CM CO CO CM CO o LO I » 3 CL CL CL a ' CL a a CL CL CL a CL CL CL a lyfc t ' TT ID ID r- oo CO z CO TT CO CO TT T* CO CO TT LI LI or 1 i i 1 i 1 1- LI J D a D o a O a a o LO IL • U. LL LL u. LL LL LL LL u-LU LU O CL CL CL CL CL CL CL CL a i - or i -0) CO CO O CO 01 o CO O O CO co co 01 CD in 00 oo oi o > 1- CJ ~— CO CO r- GO 01 T- CM CM in CD CD r- r- CO LO CO > « 1- * CO O O in CO O tn O C O o CO O o CO >-> E 01 co 00 O CO O O O TT t- O o T— sr co \ Oi O O 01 01 O 01 o o O o 0) o O o -1 Z DI T— T— T— T— T— T- T-3 LU jr CM co » TT CO CO in 10 CM cn cs (S T- IS T- in in T" T- CO o in CJ .—* O T- T- CO TT TT 10 10 CO 00 00 CO 0) 0) 01 O E S« 1- o — LO TABLE F . 4: POWER D I S S I P A T E D AT THE POINT OF FLOW TRANSITION: S t o n e G r o u n d w o o d (SGW-1) STOCK Cm (%) BULK DENSITY (kg/m**3) STOCK Cv (%) TEST REFERENCE ID. HOUSING & ROTOR USED FLOW TRANSITION ( A C C E L ) POWER, W/m**3 ROTATION (rpm) TORQUE (N.m) ACCEL DECEL e. 1 1010 9 . 23 PFD.081 PF2/PFH1 2241 7.9 5.82+0.98 E05 3.22+0.74 E05 6. 1 1010 9.23 PFD.082 PF2/PFH1 2535 10.4 8.82+2.19 E05 2.21+0.90 E05 9.0 1000 13.6 PFD.083 PF2/PFH1 3670 17.8 2. 17+0.10 E06 1 . 6 9 ± 0 . 3 2 E06 9.0 1000 13.6 PFD.084 PF2/PFH1 3341 16. 1 1.78+0.15 E06 1.06+0.27 E06 10.0 998 15.0 PFD.069 PF2/PFH1 4552 24.3 3.68+0.53 E06 2 . 2 5 ± 0 . 2 2 E06 10.0 998 15.0 PFD.070 PF2/PFH1 2952 10.9 1 . 0 7 ± 0 . 3 5 E06 1 . 9 2 ± 0 . 1 9 E06 T I T L E F . 5 : POWER D I S S I P A T E D AT THE POINT OF FLOW TRANSITION: T h e r m o m e c h a n i c a l P u l p (TMP-1) 2 STOCK Cm (%) BULK DENSITY (kg/m**3) STOCK Cv (%) TEST REFERENCE ID. HOUSING & ROTOR USED FLOW TRANSITION ( A C C E L ) POWER, W/m**3 ROTATION ( rpm) TORQUE (N.m) ACCEL DECEL 9.8 1010 15.6 PFD.071 PF2/PFH1 4340 26.5 3.81+0.19 E06 2.04+0.19 E06 9.8 1010 15.6 PFD.072 PF2/PFH1 3921 22.5 2.93+0.40 E06 1. 2 2 ± 0 . 0 4 E06 to 00 A p p e n d i x G V e l o c i t y a n d T u r b u l e n c e M e a s u r e m e n t s G . l L a s e r D o p p l e r V e l o c i m e t e r An attempt was made to measure the velocity and turbulence of flows in the pulp flu-idizer using a laser Doppler velocimeter (LDV) . This non-intrusive technique measures the instantaneous velocity of particles suspended in a flow. Light scattered from the particles as they pass through the intersection region of two laser beams is detected, and the frequency of the scattered light converted into the particle velocity. Details of the L D V technique can be found in a number of texts [e.g. Drain, 1980; Durst et al., 1976]. It was not known if a suitable signal could be obtained for medium consistency pulp suspensions, although a number of researchers had previously used this technique to study low consistency pulp flows up to approximately 1.5% Cm [Ek, 1979; Duffy and Norman, 1979; Kerekes and Garner, 1982]. A Thermo-Systems Incorporated (TSI) L D V was used. This consisted of a 1 W Lexel argon ion laser, a frequency tracker (Model 1090), a frequency shift system (Model 980), a photomultiplier (Model 960) and related optics. Due to the geometry of the pulp fluidizer and the opacity of the pulp suspensions, the L D V was used in the backward scatter dual-beam mode. A number of different particles including gas bubbles, nylon and pulp fibres, and milk, were used to seed the flow. Despite considerable effort a useful signal, that is one validated by the L D V system, could not be obtained, even at 285 APPENDIX G. VELOCITY AND TURBULENCE MEASUREMENTS 286 typical seed particle concentrations. This failure was attributed to a number of factors: 1. The level of light detected in the backscatter mode is significantly less (around 1000 times less) than that detected in the forward scatter mode. 2. Reflections from the inner surfaces of the pulp fluidizer chamber (constructed of 316 SS) may have interfered with the signal tracking processor. 3. During operation, the lexan plate covering the chamber flexed. As the cover flexed, it acted like a moving lens and disturbed the crossing of the laser beams. G.2 H i g h S p e e d C i n e m a t o g r a p h y Some information on time-average flow velocities was obtained by digitizing floe motion from high speed cine films. It must be emphasized that data obtained in this manner are only approximate and only represent a limited biased sampling of the flow in the pulp fluidizer. A Hycam motion picture camera capable of reaching framing rates of 5000 pps (pictures per second) was used in the tests. Due to film acceleration, the framing rate during a test varied from 1000 to 5000 pps. Timing marks generated on the film at 1000 Hz permitted accurate measurement of the time interval between film frames. Suspension motion in the fluidizer was quantified by following the movement of floes (which appear as darker regions on the film) over time intervals of up to 0.1 second. This technique allowed calculation of the average velocity and direction of flow in the the suspension. However, no turbulence information could be obtained, and suspension motion could only be measured in regions were floes existed and could be readily followed. Before a test, the fluidizer was packed with pulp and operated at the desired rota-tional speed. Once a steady flow had been established, the Hycam camera was started APPENDIX G. VELOCITY AND TURBULENCE MEASUREMENTS 287 set for a framing rate of 5000 pps. Approximately 2 seconds of flow was recorded. After the fdm was processed, the timing marks on the film were used to obtain a curve giving the sequential frame number versus framing rate. A n L.W. International 224-ES motion analyser was used to project the film on a digitizing board. The dig-itizing board was calibrated using the projected image of the fluidizer chamber and its known dimensions. Once calibrated, the film was stepped through frame by frame. When a suitable floe was identified (one that could be followed for 5 or more frames), its frame number was recorded and location digitized with respect to the centre of the fluidizer. The film was then stepped forward, carefully following the movement of the floe. After the floe had moved a suitable distance (an absolute distance of more than 5 mm) its position was again digitized and frame number recorded. The floe position was now known at two times. The direction and distance travelled between floe im-ages were determined. The average framing rate between the two frames was used to calculate the time interval between them. The average velocity was then calculated by dividing the distance of floe motion by the measured time interval. This procedure was repeated for different floes until a profile of suspension motion in the fluidizer was obtained. The information obtained from the analysis of two flow patterns is presented as vector diagrams in Figures 3.14 and 3.17. It was estimated that floe positions could be measured to an accuracy of ± 1 mm, while the time interval between frames could be measured to within 10-15%. Hence the velocities were accurate to between 30 and 55%. A p p e n d i x H C h a n g e s i n P u l p P r o p e r t i e s D u r i n g D y n a m i c T e s t s During a dynamic test pulp fibres receive mechanical treatment which alter their phys-ical properties. To determine the extent to which pulp properties changed, a series of tests was conducted in which a semi-bleached kraft pulp (SBK-2) was exposed to increasing energy treatment in the pulp fluidizer using both the narrow and wide-gap configurations. In addition, pulp was refined in a standard P F I mi l l 1 to provide a ref-erence point for the fluidizer tests. Results from these experiments are tabulated in Tables H.I and H.2. Those samples treated in the wide-gap (50 mm) configuration at both 6.4 and 9.7% C m displayed changes in pulp properties similar to those of beating. There was a reduction in tear index, bulk and opacity, and an increase in tensile strength (or breaking length), stretch and burst index. There was no significant reduction in fibre length. For samples treated in the narrow-gap (5.0 mm) configuration there was initially a beating action which rapidly reduced the freeness of the pulp (from 680 to 386 mL C S F 2 ) , a decrease in bulk, tear index and opacity, and an increase in tensile strength, stretch, burst index and air resistance. However, further energy input increased the 1 The PF I mil l is a smooth bedplate type beater used to reproducibly beat small quantities of pulp in a laboratory. See C P P A C.7 or T A P P I T248 hm-85. 2 Canadian Standard Freeness, a measure of the drainage resistance of pulp. See C P P A C . l or T A P P I T227 om-85. 288 APPENDIX II. CHANGES IN PULP PROPERTIES 289 100 200 E n e r g y T r e a t m e n t , M J / t o n n e p u l p 300 Figure H . l : Curl vs. energy treatment for SBK-2 fibres in the narrow-gap configuration of the pulp fluidizer. tear index and bulk, with no further change in C S F . Burst index and tensile strength decreased but stretch increased considerably. This suggested that curl and microcom-pressions had been introduced into the fibres [Page et al., 1985], which was confirmed by curl measurements made using image analysis at P A P R I C A N 3 . Cu r l 4 progressively increased as the fibres were subjected to continued shear as shown in Figure H. l . The non-treated fibres were only moderately curly compared with treated fibres which were highly curly as shown in Figure H.2. 3 Curl measurements were made by Byron Jordan of PAPRICAN, Pointe Claire, Quebec. 4The curl index is denned as [(fibre contour length)/(longest dimension) -1]. It is the fractional increase in fibre length that would result if the fibres were straightened but not stretched. The average curl index for a straight-fibred pulp is about 0.1 and that for a curly pulp is about 0.2. See {Page et al., 1985]. APPENDIX H. CHANGES IN PULP PROPERTIES 290 Figure H 2: Photographs of semi-bleached kraft pulp (SBK-2) before and after treat-ment,n the narrow-gap configuration of the pulp fluidizer. (a) untreated, (b) treated tor 35 seconds at 5000 rpm for a total energy input of 270 M J / t pulp. Test P F D 105 Photographs by G. Williams of P A P R I C A N , Vancouver. APPENDIX H. CHANGES IN PULP PROPERTIES 291 The photograph in Figure H.2(b) also shows that the fibres subjected to intense shear in the fluidizer had microcompressions and dislocations introduced into their walls. When the fibres were viewed in polarized light, the surfaces of the treated fibres appeared highly fibrillated, indicative of beating. These observations corroborated the evidence obtained from the physical tests of handsheets made from these pulps. Thus, mechanical treatment of pulp in the fluidizer initially beated and then curled fibres as treatment was continued. The tear index versus tensile strength development for the semi-bleached kraft pulp treated in the fluidizer is given in Figure H.3. The curve for the P F I treatment of the same pulp shows strength development typical of West Coast softwood semi-bleached krafts. As shown in Figure H.3, at any given breaking length, the pulp treated in the fluidizer had a higher tear index than pulp refined in the PF I mil l . For pulp treated in the wide-gap configuration, the tear index-tensile strength decreased to a midpoint along the PF I curve and then showed little sign of further change. However, when the pulp was treated in the narrow-gap configuration, pulp initially changed rapidly but then began to lose tensile and increase in tear index. In all cases it would appear that curl began to be developed immediately, accounting for the fact that all curves he above the PF I curve. The effect of energy input on pulp suspension properties was evident in plots of energy treatment versus tensile strength, tear index and freeness given in Figures H.4, H.5 and H.6. It was likely that the rate of energy expenditure, or rate of shear, ex-perienced by the pulp during its treatment determined the rate of change in physical properties. Changes in pulp physical properties accounted for some of the behaviour observed in the dynamic tests discussed in Chapter 3. For example, the onset of flow transition changed after extended energy input. Therefore, the conditions under which most dy-namic tests were conducted was a compromise between being sufficiently slow to observe APPENDIX H. CHANGES IN PULP PROPERTIES 292 4.0 6.0 8.0 10.0 12.0 B r e a k i n g L e n g t h , k m Figure H.3: Tear index vs. tensile strength for SBK-2 . The arrows indicate the direction in which pulp properties change with increased treatment. APPENDIX H. CHANGES IN PULP PROPERTIES 293 o o i o CO -km rt - " km Length, 6.0 Breaking l 4.0 t\i A = 50 mm gap, 6.4% C m v = 50 mm gap, 9.7% C m o = 5 mm gap, 9.2% C m O d 0 100 200 300 Energy Treatment, MJ/tonne pulp Figure H.4: Tensile strength vs. energy input for SBK-2 treated in the pulp fluidizer. APPENDIX II. CHANGES IN PULP PROPERTIES 294 o co a © in A = 50 m m gap, 6.4% CT v = 50 m m gap, 9.7% C„ o = 5 m m gap, 9.2% C m 100 200 E n e r g y T r e a t m e n t , M J / t o n n e p u l p 300 Figure II.5: Tear index vs. energy input for SBK-2 treated in the pulp fluidizer. APPENDIX H. CHANGES IN PULP PROPERTIES 295 o 0 100 200 300 E n e r g y T r e a t m e n t , M J / t o n n e p u l p Figure H.6: C S F vs. energy input for SBK-2 treated in the pulp fluidizer. APPENDIX H. CHANGES IN PULP PROPERTIES 296 flow changes and sufficiently fast to avoid substantial changes to pulp properties. In mill situations high-shear M C mixers expose pulp to brief periods of intense shear. Energy input will vary but is generally between 8-43 M J / t pulp (Table 1.8). From Figures H.4 through H.6 it is evident that while difficult to estimate the exact change in pulp physical properties at these lower energy inputs, some change will occur. Likely this will have to be determined for each type of mixer. As pulp treated in a mill sees a number of M C mixers and pumps during processing, a cumulative effect may occur and result in significant changes in pulp physical properties. M C mixers are used for bleaching in research laboratories and typical mixing times are on the order several seconds. For example, Reeve et al. [1985] report mixing times of 10 seconds and a total energy treatment of up to 180 M J / t pulp. Since laboratory M C mixers are similar in design to the pulp fluidizer, the treatment would be expected to significantly alter the physical properties of the pulp. However, the extent of the effect and how, or if, it would affect the results obtained from bleaching experiments has yet to be determined. TABLE H.1: PULP PROPERTIES VS. ENERGY TREATMENT IN THE PULP F L U I D I Z E R fa fa fa ft SAMPLE I D E N T I F I C A T I O N PFD.090 PFD.091 PFD.092 PFD.094 PFD.095 PFD.096 T E S T CONDITIONS U n i t s R o t o r / H o u s i n g PF2/PFH1 PF2/PFH1 PF2/PFH1 PF2/PFH1 PF2/PFH1 PF2/PFH1 Gap W i d t h mm 50 50 50 50 50 50 V o l u m e 1 3. 16 3. 16 3. 16 3. 16 3. 16 3. 16 P u l p M a s s C o n c e n t r a t i o n Cm. % 6.4 6.4 6.4 9.7 9.7 9.7 B u l k D e n s i t y g/cm' 1 .01 1 .03 1 .04 0.96 1 .00 1 .02 V o l u m e C o n c e n t r a t i o n Cv, % 12.5 12.7 12.8 17.9 18.9 19. 1 T i m e a t Max. rpm s 5 15 30 5 20 40 Max. T e m p e r a t u r e R e a c h e d °C 25.8 34.5 47.2 20.6 3 5 . 1 35 . 1 Maximum S h e a r R a t e S " 1 511 486 492 516 515 504 Power I n p u t W/m1 5.56E06 5.55E06 5.67E06 2.90E06 5.42E06 5.56E06 E n e r g y I n