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Hydrodynamics of spout fluid beds Sutanto, Willy 1983

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HYDRODYNAMICS OF SPOUT FLUID BEDS By WILLY SUTANTO B.Eng. McGill University, 1981 A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF APPLIED SCIENCE i n THE FACULTY OF GRADUATE STUDIES (Department of Chemical Engineering) We accept t h i s thesis as conforming to the required standard July 1983 © Wi l l y Sutanto, 1983 In presenting t h i s thesis i n p a r t i a l f u l f i l m e n t of the requirements for an advanced degree at the University of B r i t i s h Columbia, I agree that the Library s h a l l make i t f r e e l y available for reference and study. I further agree that permission for extensive copying of t h i s thesis for scholarly purposes may be granted by the head of my department or by his or her representatives. I t i s understood that copying or publication of t h i s thesis for f i n a n c i a l gain s h a l l not be allowed without my written permission. Department of The University of B r i t i s h Columbia 1956 Main Mall Vancouver, Canada V6T 1Y3 Date D E - 6 ( 3 / 8 1 ) ABSTRACT Experiments were conducted i n a s p o u t - f l u i d bed, a modified version of a standard spouted bed, incorporating a u x i l i a r y flow i n addition to c e n t r a l flow. The a u x i l i a r y flow was supplied i n three d i f f e r e n t ways through the perforated conical d i s t r i b u t o r base. The ve s s e l used was a c y l i n d r i c a l half column, 0.15 m i n diameter and 1.05 m high f i t t e d with an i n l e t o r i f i c e plate with a diameter of either 19.1 mm or 25.4 mm. The three s o l i d materials studied were: polystyrene, m i l l e t and high density polyethylene (HDPE). Aspects studied included regime maps, minimum f l u i d flowrate for spouting with aeration and s p o u t - f l u i d i z a t i o n , annulus gas v e l o c i t y p r o f i l e , t o t a l bed pressure drop, annulus s o l i d s c i r c u l a t i o n , fountain shape and height and spout shape and diameter. For d i f f e r e n t c e n t r a l f l o w / a u x i l i a r y flow combination, four types of flow behaviour were established: packed bed; spouting with aeration; s p o u t - f l u i d i z a t i o n and j e t i n a f l u i d i z e d bed. The minimum t o t a l f l u i d flowrate for spouting with aeration and s p o u t - f l u i d i z a t i o n was always found to be greater than the minimum spouting v e l o c i t y . Greater f l u i d percolation through the annulus i n the c y l i n d r i c a l part of the column was achieved by increasing the amount of a u x i l i a r y flow for a constant t o t a l flow. As much as a 50% increase could be r e a l i z e d for a 1:1 s p l i t between c e n t r a l / a u x i l i a r y flow compared with the case where there i s no a u x i l i a r y flow. The c i r c u l a t i o n rate of s o l i d p a r t i c l e s was affected l i t t l e by small rates of aeration. At higher rates of aeration and for deeper bed - i i i -heights aeration led to an increase of s o l i d s c i r c u l a t i o n . However, at lower bed heights, the s o l i d c i r c u l a t i o n rate decreased as a r e s u l t of aeration. The o v e r a l l bed pressure drop for spouting with aeration under minimum conditions increases l i n e a r l y with a u x i l i a r y flow. Fountain height was found to decrease as the f r a c t i o n of a u x i l i a r y flow increased. A greater t o t a l gas flow i s required to reach a given fountain height for spouting with aeration. However, with aeration, the fountain was observed to have a greater s o l i d s concentration than that for pure spouting. The empirical c o r r e l a t i o n due to McNab was found to predict the average spout diameter very well under various ce n t r a l and a u x i l i a r y flow combinations i f the sum of central and a u x i l i a r y flows i s used i n the c o r r e l a t i o n . - i v -TABLE OF CONTENTS Page ABSTRACT i LIST OF TABLES v i LIST OF FIGURES v i i ACKNOWLEDGMENTS x i CHAPTER 1 - INTRODUCTION 1 CHAPTER 2 - LITERATURE REVIEW 5 2.1 Regime Maps 5 2.2.1 Minimum Total F l u i d Flow For Spouting with Aeration 9 2.2.2 Minimum Total F l u i d Flow For Spout-Fluidization 12 2.3 Longitudinal Annular F l u i d V e l o c i t y and Overall Bed Pressure Drop 12 2.4 Annular Solids C i r c u l a t i o n Rate 14 2.5 Fountain Shape and Height 15 2.6 Spout Shape and Diameter 15 CHAPTER 3 - APPARATUS AND BED MATERIALS 16 3.1 Apparatus 16 3.2 S o l i d Properties 26 CHAPTER 4 - CHOICE OF EXPERIMENTAL CONDITIONS 30 4.1 Points of Entry for A u x i l i a r y A i r Flow 30 4.2 Central Flow and A u x i l i a r y Flow Combination 30 CHAPTER 5 - REGIME MAPS AND MINIMUM FLUID FLOWRATE FOR SPOUTING WITH AERATION AND SPOUT-FLUIDIZATION 31 5.1 Experimental Technique 31 5.2 Results and Discussion 34 5.2.1 Regime Maps 34 5.2.2 Minimum F l u i d Flowrate 47 - v -Page CHAPTER 6 - LONGITUDINAL ANNULAR GAS VELOCITY AND OVERALL BED PRESSURE DROP FOR SPOUTING WITH AERATION 53 6.1 Measurement Technique.. 53 6.2 Results and Discussion 54 6.2.1 Longitudinal Annulus Gas V e l o c i t y 54 6.2.2 O v e r a l l Bed Pressure Drop 65 CHAPTER 7 - PARTICLE VELOCITY IN THE ANNULUS 68 7.1 Measurement Technique 68 7.2 Results and Discussion 68 CHAPTER 8 - FOUNTAIN SHAPE AND HEIGHT AND SPOUT SHAPE AND DIAMETER 74 8.1 Measurement Technique 74 8.2 Results and Discussion 74 8.2.1 Fountain Shape and Height 74 8.2.2 Spout Shape and Diameter 76 CHAPTER 9 - CONCLUSIONS AND SUGGESTIONS FOR FURTHER WORK 80 NOTATION 82 REFERENCES 85 APPENDICES 87 I - Pressure Drop-Gas V e l o c i t y Equations For Loosely-Packed Bed of The Solids M a t e r i a l Investigated 88 II - Solid-Free Pressure Drop-Central Flow Correction Curve... 89 II I - C a l i b r a t i o n Curves For O r i f i c e Plate Flow Meters 90 IV - Dimensions For O r i f i c e Plate Flow Meters 94 V - Experimental Conditions Designation 95 VI - Experimental Data 98 - v i -LIST OF TABLES Page Table 1 Properties of S o l i d P a r t i c l e s used 29 Table 2 Values of Empirical Constant K and Slopes of the Line A-C for D i f f e r e n t Systems Investigated 50 Table 3 Normalized Values of Central and A u x i l i a r y Flow at Minimum S p o u t - f l u i d i z a t i o n Conditions and the Maximum Spoutable Heights for the Systems Investigated 52 Table 4 Comparison of the Values of ( p g - p ) ( l - e ^ ) g and f < U m f > 6 6 Table 5 Predicted Values of Average Spout Diameter Using McNab's Empirical C o r r e l a t i o n [polystyrene p a r t i c l e s ] 79 Table V . l Values of Nl for Di f f e r e n t Combinations of Bed Mat e r i a l , Bed Height and Inl e t O r i f i c e Diameter 96 Table V.2 Values of N2 for D i f f e r e n t Dependent Variables Investigated 97 Table V.3 Values of N3 f o r D i f f e r e n t A u x i l i a r y Flow Configuration 97 - v i i -LIST OF FIGURES Page Figure 1 Schematic diagram of a spouted bed 2 Figure 1.2a Schematic diagram of a s p o u t - f l u i d bed with conical base d i s t r i b u t o r 3 Figure 1.2b Schematic diagram of a sp o u t - f l u i d bed with f l a t base d i s t r i b u t o r 3 Figure 2.1a Regime map due to Chatterjee (1974) 6 Figure 2.1b Regime map due to Littman (1982) 6 Figure 2.1c Regime map due to Dumistrescu (1977) 7 Figure 2.2 Hypothetical phase diagram 7 Figure 3.1 Schematic diagram of the column 17 Figure 3.2 Diagram of i n l e t o r i f i c e plate with pressure tap 18 Figure 3.3a Conical base d i s t r i b u t i o n section 19 Figure 3.3b Sectional side view of the co n i c a l d i s t r i b u t o r 20 Figure 3.4 Flattened out Surface of the co n i c a l perforated d i s t r i b u t o r 22 Figure 3.5 Schematic diagram of the experimental set-up 23 Figure 3.5a O r i f i c e plate flow meter assembly 24 Figure 3.6 P i c t u r e of the experimental set-up 25 Figure 3.7 Schematic diagram of s t a t i c pressure probe 27 Figure 5.1 Regime map [System: polystyrene, d. = 1.91 cm H = 60 cm] 35 Figure 5.2 P h y s i c a l appearances of various flow regimes... 36 Figure 5.3 P h y s i c a l appearance of s p o u t - f l u i d i z a t i o n [polystyrene, H=30 cm, d^ . = 1.91 cm, Q T - 9 1/s, r 1 = 1] 38 - v i i i -Page Figure 5.4 The t r a n s i t i o n state between s p o u t - f l u i d i z a t i o n and submerged j e t i n f l u i d i z e d bed of the type JF(I) 40 Figure 5.5 The t r a n s i t i o n between s p o u t - f l u i d i z a t i o n and submerged j e t i n f l u i d i z e d bed of the type JF(I) 41 Figure 5.6 Regime map (System: polystyrene, d. = 1.91 cm H = 30 cm) 43 Figure 5.7 Regime map [System: polystyrene, d. = 1.91 cm H = 45 cm] 43 Figure 5.8 Regime map [System: HDPE, d. = 1.91 cm, H = 30 cm] 44 Figure 5.9 Regime map [System: HDPE, d. = 1.91 cm, H = 35 cm] 44 Figure 5.10 Regime map [System: m i l l e t , d. = 1.91 cm, H = 30 cm] 45 Figure 5.11 Regime map [System: m i l l e t , d. = 1.91 cm, H - 45 cm] t , 45 Figure 5.12 Regime map [System: polystyrene, H = 45 cm, d ± = 2.54 cm] 46 Figure 5.13 Regime map [System: m i l l e t , H = 30 cm, d ± = 2.54 cm] 46 Figure 6.1 E f f e c t of a u x i l i a r y gas flow on annulus gas s u p e r f i c i a l v e l o c i t y [Q T/Q r a e = 1.25, d ± = 1.91 cm] t . . ? ! 55 Figure 6.2 Percent increase of annulus gas v e l o c i t y due to a u x i l i a r y flow [Q T/Q m c = 1.25, d. = 1.91 cm] t..?f 57 x Figure 6.3 Annulus gas s u p e r f i c i a l v e l o c i t y for d i f f e r e n t bed heights [system: polystyrene, d^ = 1.91 cm, VQ m s = 1 - 2 5 J 5 8 - i x -Page Figure 6.4 Relationship between U^^AHm and Z/H for d i f f e r e n t values of r f l [d^ = 1.91 cm] 59 Figure 6.5 Relationship between U^^AHm and Z/H f o r di f f e r e n t values of r [d. = 2.54 cm] 61 a i Figure 6.6 Relationship between UA.^mf a n c * ^^m ^ o r d i f f e r e n t a u x i l i a r y gas flow entry configuration [System: polystyrene, d ± = 2.54 cm, H = 60 cm, Q T/Q m s - 1-25] 63 Figure 6.7 Relationship between U^/U^ and Z/Hm for di f f e r e n t i n l e t o r i f i c e diameter [system: polystyrene, H = 60 cm, Q x/Q m s = 1.25] 63 Figure 6.8 Ef f e c t of the f r a c t i o n of a u x i l i a r y flow on the f r a c t i o n of gas which flows through the annulus [polystyrene, H = 60 cm, d^ = 1.91 cm, Q T = 8 1/s] 64 AP g Figure 6.9 Relationship between (-r=~) and [q /Q A AP^ msa msa mf for d i f f e r e n t i n l e t o r i f i c e diameters, bed heights and a u x i l i a r y flow configurations [System: polystyrene] 67 Figure 7.1 Relationship between p a r t i c l e v e l o c i t y , Vp, and Q>f/Qms f ° r d i f f e r e n t bed heights [System: polystyrene, d^ = 1.91 cm, q = 0] 70 Figure 7.2 Relationship between p a r t i c l e v e l o c i t y Vp, and the proportion of a u x i l i a r y flow, r , for 3-d i f f e r e n t bed heights. [System: polystyrene, d ± = 1.91 cm, Q T/Q m s = 1.4] 70 Figure 7.3a Relationship between p a r t i c l e v e l o c i t y , Vp, and f r a c t i o n of a u x i l i a r y flow with configuration #2 [System: polystyrene, H = 60 cm, d ± - 1.91 cm] 71 Figure 7.3b Relationship between p a r t i c l e v e l o c i t y , Vp, and f r a c t i o n of a u x i l i a r y flow with configuration #3 [System: polystyrene, H = 60 cm, d ± = 1.91 cm] 71 Figure 7.4a R e l a t i o n s h i p between p a r t i c l e v e l o c i t y , Vp, and f r a c t i o n of a u x i l i a r y flow w i t h c o n f i g u r a t i o n #2 [System: HDPE, H = 30 cm, d ± = 1.91 cm] Figure 7.4b R e l a t i o n s h i p between p a r t i c l e v e l o c i t y , Vp, and f r a c t i o n of a u x i l i a r y flow w i t h c o n f i g u r a t i o n #3 [System: HDPE, H = 30 cm, d ± = 1.91 cm] Figure 8.1 E f f e c t of 0 ^ / 0 ^ on Hp f o r d i f f e r e n t values of bed heights [System: polystyrene, q = 0, d ± = 1.91 cm] Figure 8.2 R e l a t i o n s h i p between f o u n t a i n height, H p, and the f r a c t i o n of a u x i l i a r y flow w i t h c o n f i g u r a t i o n #1 f o r d i f f e r e n t bed heights [System: polystyrene, Q T/Q m s = 1.4, d, = 1.91 cm] Figure 8.3a E f f e c t of the f r a c t i o n of a u x i l i a r y flow w i t h c o n f i g u r a t i o n #2 on f o u n t a i n height [System: p o l y s t y r e n e , H = 60 cm, d, = 1.91 cm] Figure 8.3b E f f e c t of the f r a c t i o n of a u x i l i a r y flow w i t h c o n f i g u r a t i o n #3 on fo u n t a i n height H. [System: polystyrene, H = 60 cm, d, = 1.91 cm] Figure 8.4 Sketches showing spout shapes f o r various s o l i d m a t e r i a l s i n v e s t i g a t e d - x i -ACKNOWLEDGMENTS I would l i k e to express my appreciation to Dr. N. Epstein and Dr. J.R. Grace for t h e i r thoughtfulness and advice, under whose guidance and encouragement t h i s work was ca r r i e d out. I am g r a t e f u l to Dr. C.J. Lim for his h e l p f u l discussions and suggestions. F i n a l l y , s p e c i a l thanks are also due to the gentlemen of the Department of Chemical Engineering workshop and stores for t h e i r e n t h u s i a s t i c and invaluable assistance. CHAPTER 1 INTRODUCTION F l u i d i z a t i o n has been widely accepted as a s o l i d - f l u i d contacting technique. R e l a t i v e l y f i n e (dp <^  1 mm) p a r t i c l e s are desirable for good qu a l i t y f l u i d i z a t i o n operations. The a p p l i c a t i o n of the spouted bed technique as an a l t e r n a t i v e to f l u i d i z a t i o n f o r handling coarse p a r t i c l e s (dp >^  1 mm) has achieved increased recognition In recent years [K.B. Mathur and N. Epstein (1974)]. F i g . 1.1 i l l u s t r a t e s schematically a t y p i c a l spouted bed column with a conical base. Under conditions of spouting, the bed consists of two d i s t i n c t zones: the very d i l u t e phase cen t r a l core c a l l e d the spout, and the surrounding dense phase annular s o l i d s c a l l e d the annulus. The upward moving p a r t i c l e s i n the spout, having reached a c e r t a i n height above the bed surface, f a l l back onto the annulus where they slowly move downwards and, to some extent, r a d i a l l y inwards as a loosely packed bed. F l u i d from the spout percolates through these annular s o l i d s as i t travels upwards. Various modifications to standard spouted beds have resulted i n a wide range of useful applications [H. Kono (1981), K.B. Mathur and N. Epstein (1974)]. One such modification introduces f l u i d to the annulus d i r e c t l y from an external source i n order to increase the f l u i d p e rcolation through the annulus, e s p e c i a l l y i n the lower section. In add i t i o n to supplying spouting f l u i d through a c e n t r a l l y located opening, a u x i l i a r y f l u i d i s supplied through a f l a t or conical porous/perforated d i s t r i b u t o r as shown l n Figures 1.2a and 1.2b. This - 2 -F O U N T A I N B E D S U R F A C E S P O U T A N N U L U S S P O U T - A N N U L U S I N T E R F A C E C O N I C A L B A S E F L U I D I N L E T F i g . 1.1. Schematic diagram of a spouted bed FOUNTAIN A N N U L U S S P O U T -A U X I L I A R Y F L U I D I N L E T S P O U T I N G FLUID I N L E T F i g . 1.2a Schematic diagram of a s p o u t - f l u i d bed with c o n i c a l base d i s t r i b u t o r . i i F i g . 1.2b Schematic diagram of a s p o u t - f l u i d bed w i t h f l a t base d i s t r i b u t o r . - 4 -p a r t i c u l a r modified spouted bed, usually known as a "spout-fluid bed", i s obtained by aerating or f l u i d i z i n g the annular s o l i d s . Spout-fluid beds show better s o l i d s mixing and annular s o l i d - f l u i d contact than standard spouted beds. In addition, they are better for sticky or agglomerating s o l i d p a r t i c l e s . A large amount of information exists on the hydrodynamics of spouted beds and f l u i d i z e d beds. R e l a t i v e l y l i t t l e information i s , however, av a i l a b l e for either gas or l i q u i d s p o u t - f l u i d beds. Quite often, the fragmentary information obtained by one worker d i f f e r s considerably from that of another. The disagreement can pa r t l y be at t r i b u t e d to differences i n column and i n l e t geometry, p a r t i c l e and f l u i d properties and the operating conditions used. The main objective of the present research i s to study the changes i n the hydrodynamic behaviour of a standard spouted bed as modified by the addition of a u x i l i a r y flow. Hydrodynamic c h a r a c t e r i s t i c s studied are: the t o t a l minimum f l u i d flowrate and bed pressure drop f o r spouting with aeration; regime maps; l o n g i t u d i n a l f l u i d v e l o c i t y d i s t r i b u t i o n i n the annulus; p a r t i c l e c i r c u l a t i o n i n the annulus; height and shape of the fountain; and the shape and diameter of the spout. A secondary objective i s to compare the data obtained with e x i s t i n g c o r r e l a t i o n s and data where appropriate, and, wherever possible, to close the gaps i n the e x i s t i n g fragmentary information for spou t - f l u i d beds. - 5 -CHAPTER 2 LITERATURE REVIEW The s p o u t - f l u i d bed technique has e l i c i t e d great i n t e r e s t i n recent years as a modification to the simple standard spouted bed. Because the basic hydrodynamic features of the spouting remain unaltered, the present review i s confined to those aspects of spouted bed behaviour which have d i r e c t relevance to the present research and also to the very l i m i t e d information available on s p o u t - f l u i d beds. 2.1 Regime Maps: The presence of a u x i l i a r y flow y i e l d s a number of d i f f e r e n t types of bed behaviour which are generally represented by a "phase diagram" or "regime map". Regime maps determined experimentally by Chatterjee (1974), Littman et a l (1982) and Dumistrescu (1977) are shown i n Figures 2.1a, 2.1b and 2.1c, r e s p e c t i v e l y . These three regime maps, though they appear to be d i f f e r e n t from each other, share many common features: i . packed bed region, i i . f l u i d i z a t i o n , i i i . spouting with aeration of the annulus, and i v . spouting with f l u i d i z a t i o n of the annulus, or s p o u t - f l u i d i z a t i o n . A hypothetical regime map shown i n Figure 2.2 could be drawn encompassing a l l the common flow behaviours. I o c M •'rj Lu 100 60 20 0 1 F i 7\\ i \ \ \ USF OcN SF \ vie P \ i \ i V S i 0 AO REGIME DESIGNATION: F Fluidized bed USF - Unstable spout-fluid bed ' SF - Spout-fluid bed US - Unstable spouted bed P Packed bed S Spouted bed c - coordinate for minimum spout-fluidization 80 120 1A0 •Spout flow (NLPM a i r ) F i g . 2.1a Regime map due to Chatterjee (1974), [ mat e r i a l : glass beads, p = 2.41 g/cm3, H= 18.5 mm, d = 0.60 mm, d.= 5.0 mm, D = 90 mm 1 ° P i c F l u i d used: a i r LO o i 3 2 h 0 VERTICAL TRANSPORT Jet in fluidized bed ( Fluidized bed with local spout) Spout-fluid bed (H>Hmsf) F I X E D ^ ; •— BED \Spout-fluid bed (H^Hmsf 1— : I j 0 ( a /Qmf) 0.5 F i g . 2.1b Regime map due to Littman (1982) [ ma t e r i a l : calcium carbonate p a r t i c l e s , P g= 2.6 g/cm3, d = 1.8 mm, D = 70 mm, d.= 15 mm, p c i H= 60 mm ] F l u i d used: a i r - 7 -0 20 AO 60 80 100 O Spouting flow ( Nnvh ) Spouting flow F i g . 2.2 Hypothetical phase diagram - 8 -2.1.1 ( i ) Packed bed condition; QT < Q mf and Q T < Q m s This regime ex i s t s as long as the sum of the ce n t r a l flow and a u x i l i a r y flow i s less than the minimum f l u i d i z a t i o n and the minimum spouting flow. ( i i ) F l u i d i z a t i o n : QT > Qmf This regime requires a much higher a u x i l i a r y flow than central spouting flow. Varying the spouting flow and a u x i l i a r y flow can a l t e r the type of f l u i d i z a t i o n , ranging from a bubbling to a slugging behaviour. In the bubbling mode, the bubbles are formed above the i n l e t o r i f i c e plate and r i s e along the spout axis. Chatterjee denoted t h i s condition as either the unstable s p o u t - f l u i d bed regime or the unstable spouting regime, while Dumistrescu c a l l e d i t e i t h e r f l u i d i z a t i o n or bubbling. However, i f bubbles grow u n t i l t h e i r volume equivalent diameter equals or exceeds the column diameter, slugging of the upper bed material i s observed. This regime i s denoted by Littman as " j e t i n f l u i d i z e d bed". ( i i i ) Spouting with aeration: U ^ H < umf Chatterjee and Dumistrescu denoted t h i s regime as spouting while Littman named i t s p o u t - f l u i d i z a t i o n with H < H m s f . Spouting with aeration, as f a r as i t s v i s i b l e c h a r a c t e r i s t i c s are concerned, i s s i m i l a r to spouting i n a standard spouted bed. The sum of a u x i l i a r y and spouting flows i s always greater than the minimum spouting flowrate, except i n the r e s u l t obtained by Chatterjee which showed they are the - 9 -same. In a l l three studies, there appear to e x i s t l i m i t i n g values for c e n t r a l flow, ( Q m s a ) ^ . a n d a u x i l i a r y flow, ( q m s a ) m a x , below and above which respectively spouting with aeration w i l l not occur (The l i m i t i n g value i s denoted as point C i n Figures 2.1a, 2.1b and 2.1c). ( i v ) S p o u t - f l u i d i z a t i o n : U ^ H >. umf S p o u t - f l u i d i z a t i o n i s achieved i f s u f f i c i e n t a u x i l i a r y flow i s supplied to cause the annular s o l i d s at the bed surface surrounding the spout of a spouted bed to be f l u i d i z e d . The behaviour of the bed at t h i s condition resembles that of a spouted bed at H = H m where the spout i n s t a b i l i t y j u s t begins to develop. The i n s t a b i l i t y i s r e f l e c t e d by the pulsations of the spout boundary near the bed surface due to break-up of the spout into bubbles. Dumistrescu named t h i s regime "pulsed j e t " . 2.2.1 Minimum T o t a l F l u i d Flow f o r Spouting w i t h A e r a t i o n : Chatterjee (1977) found that the minimum t o t a l f l u i d flow remains constant along the l i n e L-M i n Figure 2.1a and almost equal to the minimum spouting flow: *- e' Q T, * 0 (2.1) 1 msa ms However, a c o r r e l a t i o n obtained by s t a t i s t i c a l analysis of experimental data by Dumistrescu (1977) showed that 0 T . M = 27.7 ^ m l a - + U (2.2) T msa Q ms msa where U m g was estimated from the c o r r e l a t i o n of Mathur and Gishler (1955), - 10 -ms "a ~ p V 1/3 -zgH(ps-pr D c D c p 1/2 (2.3) Thus the minimum t o t a l f l u i d s u p e r f i c i a l v e l o c i t y under aeration i s always greater than the minimum spouting v e l o c i t y . Based on the work of Vukovic" et a l (1972), Littman et a l [(1974), (1976)] showed that the minimum spo u t - f l u i d flowrate varies between Qr and Q m f ( f o r Q m f >^  Q m g) and for any given bed height, H < H m, m^s " Q - " <TT> Qmsa ms % s a mf Since therefore QT'msa = qmsa + Q: msa \f , — — ^msa ms — — — — QT'msa Qmf Grbavcic et a l (1976) found for a spouted bed that <mf A A 1 (1 - h ) 3 A c Combining equations (2.4) and (2.7) y i e l d s ^msa "mf A A 1 - / (1 - h ) 3  AC 1 - msa "mf (2.4) (2.5) (2.6) (2.7) (2.8) - 11 -However, for a deeper bed such that > Q^, equations (2.4) to (2.8) are no longer v a l i d . Further r e v i s i o n by Littman (1983) led to: 'msa %asa + %nsa ' <UAH Vmsa + <USH As>msa <2-9> The annular v e l o c i t y i n a spo u t - f l u i d bed was derived separately by Littman (1976) as: u A ( z ) T — = 1 - (1 - f - ) (1 - h m g f W ) 3 (2.10) mf mf It was assumed that for spouting with aeration at the minimum condition, USH - Umf « " Va ( 2' U ) Q T = Vmsa W i t h H < Hmsf ( 2 ' 1 2 ) Substituting Equations (2.10) and (2.11) into Equation (2.9) and assuming A^/A c = 1 y i e l d s ^T'msa _ , q m s a W l • » . ... 1 - (1 - 7^  )(1 - h m g f ) (2.13) Qmf Qmf Hjjjgf i s d i f f i c u l t to measure. Furthermore, i t i s also a function of q m s a , a r e l a t i o n s h i p not very well understood. The v a l i d i t y of Equation (2.13) i s therefore subject to unc e r t a i n t i e s . - 12 -2.2.2 Minimum Total Fluid Flow f o r Spout-fluidization The only c o r r e l a t i o n a v a i l a b l e for estimating the t o t a l flow required for s p o u t - f l u i d i z a t i o n was proposed by Chatterjee (1974). I t combines the f l u i d needed to spout a s t a t i c bed at the minimum condition with the f l u i d needed for minimum f l u i d i z a t i o n of the annulus of that spouted bed: Vrnsf = Ums + Umf " " < 2 « 1 4 > The function 0 was determined e m p i r i c a l l y to be 0 = 0.20 d p - ° - 3 2 0 d ^ ' 2 3 5 H 0 - 1 6 0 (2.15) The value of U m g was obtained from the Mathur and Gis h l e r c o r r e l a t i o n , Eq. (2.3). 2.3 Longitudinal Annular Fluid Velocity and  Overall Bed Pressure Drop The analysis of Mamuro and Hat t o r i (1968, 1970) leads to a successful expression for the l o n g i t u d i n a l f l u i d v e l o c i t y p r o f i l e and pressure drop i n a spouted bed at i t s maximum spoutable bed depth: U.(Z) 1 - (1 - Z/H ) 3 (2.16) Umf AP H - 0.75 (2.17) f m For a given column geometry, s o l i d material and spouting f l u i d , Grbavcic pressure gradient at any given l e v e l i n the annulus i s independent of bed height. Hence - 13 -UAH , . x 3 — = 1 - (1- H/H ) 3 (2.18) mf Dividing Eq. (2.16) by Eq. (2.18) y i e l d s the annular f l u i d v e l o c i t y at any given height, Z _< H _< H m: U A(Z) 1 - (1 - Z/H ) 3 — ( 2 > 1 9 ) AH 1 - (1 - H/H ) m' While the o v e r a l l pressure drop becomes: AP = 1.5 h - h 2 + 0.25 h 3 (2.20) Equations (2.16) and (2.17) were derived based on the following boundary conditions: ( i ) Z = 0, uA = 0 ( i i ) Z = H , U A = U A n = U f m' A AHm mf ( i i i ) Z = H , ,-dP, _ ,-dP. _ ,-dPs m (-dZ ) " (Szh ~ (-dZ^mf m = ( p s - p) (1 - e A ) g Conditions ( i i ) and ( i i i ) were discussed i n depth by Epstein, Lim and Mathur (1978). For a s p o u t - f l u i d bed, i s no longer zero at Z=0. Nonetheless, Equations (2.16) through (2.20) form the basis of understanding of the behaviour of a s p o u t - f l u i d bed. In an attempt to account f or the a u x i l i a r y flow, Littman (1976) modified Equation (2.18) and proposed Equation (2.10). - 14 -Assuming Darcy's law i n the annulus, d P A 1 z = k V z> (2.21) int e g r a t i n g Eq. 2.21 with U A from Eq. (2.10), and noting that ^mf = k Umf H> h e obtained f or h m g f < 1: AP AP] - f ( h .) + msf Q , msa mf 1 - f ( hmsf> (2.22) where f(hmaf) = 1-5<h-*> " ( h — > + ° ' 2 5 <h~*> msf msf msf (2.23) 2.4 Annular Solids C i r c u l a t i o n Rate; The only study i n the l i t e r a t u r e on annular s o l i d s c i r c u l a t i o n rate i n s p o u t - f l u i d beds was made by Yang (1983). Because the sp o u t - f l u i d bed was f i t t e d with a draft tube, the rate of s o l i d s c i r c u l a t i o n depended primarily on the entrainment rate of s o l i d s below the draft tube i n l e t rather than along the surface of the entire spout. Yang found that at low rates of aeration, the s o l i d c i r c u l a t i o n i s e s s e n t i a l l y s i m i l a r to that without aeration. However, at higher aeration rates, a substantial increase i n s o l i d s c i r c u l a t i o n rate i s r e a l i z e d with the same t o t a l gas flowrate. He concluded that a minimum aeration rate i s required to increase s u b s t a n t i a l l y the s o l i d s c i r c u l a t i o n rate. - 15 -2.5 Fountain Shape and Height The shape of the fountain i s well defined and i s roughly paraboloidal. Grace and Mathur (1978) formulated a t h e o r e t i c a l model, based on a force-balance a n a l y s i s , for the pr e d i c t i o n of maximum height of a fountain. They also proposed a simpler approximate equation for estimating fountain height, by ignoring the drag force: v 2 P „ _ 1 46 r omax ^s , H F " eo ' l ~ 2 g — (p - p ) J 2.6 Spout Shape and Diameter Spout shape and diameter have been determined by a number of workers from measurements using h a l f - c y l i n d r i c a l columns. I t was shown that there was no difference between spout shape obtained from measurements i n a f u l l column and a half-column [MIkhailik (1966), Lim and Mathur (1974)]. The empirical dimensional c o r r e l a t i o n of l o n g i t u d i n a l average spout diameter, d s , due to McNab (1972) i s perhaps the most popular. This gives 1.48 G ° * 4 9 D ° - 6 8 d £ s 0.41 Pb - 16 -CHAPTER 3 APPARATUS AND BED MATERIALS 3.1 Apparatus Experiments were ca r r i e d out i n a c y l i n d r i c a l half-column, 15.2 cm i n diameter by 1.05 m high, equipped with a 60° included angle co n i c a l base perforated d i s t r i b u t o r as shown i n Figure 3.1. The column was constructed from p l e x i g l a s s , except for the front f l a t surface which was made of glass. Semicircular o r i f i c e plates of diameter 1.91 cm or 2.54 cm and a coarse screen could be sandwiched between the conical base and the i n l e t section. A st r a i g h t v e r t i c a l pipe of 3.18 cm I.D. and 30 cm long formed the approach section. A 2.54 cm long 'honey comb' type flow straightening bundle was fixed inside t h i s approach section. Bed pressure drop measurements were provided by two pressure taps. One was i n the approach section, 5 cm upstream from the i n l e t o r i f i c e p late. The other was situated i n the o r i f i c e plate i t s e l f , achieved by having a 0.75 mm hole d r i l l e d through each of the o r i f i c e plates and a small diameter s t a i n l e s s s t e e l tube inserted as shown i n F i g . 3.2. The other end of the tube was connected to a U-tube l i q u i d manometer. The c o n i c a l base section i s shown i n Figures 3.3a and 3.3b. The perforated annulus d i s t r i b u t o r was constructed from f i v e layers of equal thickness p l e x i g l a s s plates, machined and glued to form a single piece. The number and siz e of d i s t r i b u t o r openings were determined such that the pressure drop across the d i s t r i b u t o r equalled 25.4 cm H2O at a s u p e r f i c i a l gas v e l o c i t y of 1 m/s. There were 35 openings, each 3 mm i n - 17 -15.2 cm HALF-CYLINDRICAL SECTION 92.5cm CONICAL SECTION 12.5 cm ORIFICE PLATE & PRESSURE TAP [ AUXILIARY FLOW LINES |mj|_. STRAIGHTENING BUNDLE VERTICAL APPROACH F i g . 3.1 Schematic diagram of the column F i g . 3.2 Diagrams of i n l e t o r i f i c e plate with pressure tap Fig..3.3a Conical base d i s t r i b u t o r s e c t i o n . Scale 1:2 A LAYER OF SUBDISTRIBUTOR D I F F U S E R CALMING CHAMBER AN INLET FOR AUXILIARY FLOW PRESSURE T A P F i g . 3.3b Sectional side view of the conical d i s t r i b u t o r . Scale 1:1.5 - 21 -diameter, evenly spaced throughout the entire c o n i c a l surface as shown i n F i g . 3.4. The d i s t r i b u t o r assembly was a c t u a l l y composed of f i v e layers of subdistributor stacked together (see F i g . 3.3b) with each subdistributor leading to a separate a u x i l i a r y gas supply l i n e . Gas flow through each of these f i v e l i n e s could be controlled independently. A d i f f u s e r , was provided at the outlet end of each a u x i l i a r y gas supply l i n e to provide uniform gas flow across the d i s t r i b u t o r openings. These d i f f u s e r s were a l l housed inside the calming chambers (see F i g . 3.3b). This d i s t r i b u t o r design provided great f l e x i b i l i t y , enabling the a u x i l i a r y flow to be introduced i n a v a r i e t y of d i f f e r e n t ways. A 75 mesh s t a i n l e s s s t e e l screen was secured over the conical surface on the inside to prevent p a r t i c l e s from entering or blocking the a u x i l i a r y a i r d i s t r i b u t o r openings. A i r flowrates were monitored by s i x o r i f i c e plate flowmeters, one fo r the c e n t r a l spouting a i r supply and one for each of the f i v e a u x i l i a r y a i r chambers. Dimensions are given i n the Appendix IV. C a l i b r a t i o n was carried out with a dry gas meter.* The upstream a i r pressure of the o r i f i c e plate flowmeter was indi c a t e d by a pressure gauge (see F i g . 3.5b). A l l a i r flowrates were corrected to 20°C and one atmosphere. A c y l i n d r i c a l buffer tank 25 cm i n diameter and 60 cm high was connected to the main a i r supply l i n e to reduce incoming pressure f l u c t u a t i o n s . A schematic flow diagram and the p i c t u r e of the experimental set-up i s shown i n Figures 3.5a and F i g . 3.6 respectively. *Model AL425, by Canadian Meter Company Limited. I to F i g . 3.4 Flattened out surface of the: conical perforated d i s t r i b u t o r I static pressure probe orifice plate flowmeters assembly (see Fig. 3.6 ) inclined manometer spout-fluid bed column manometer H—PO-V main air supply line N5 Fig. 3.5a Schematic diagram of the experimental set-up - - 2 4 -r a u x i l i a r y flow l i n e # 1 # 2 # 3 # A-# 5-c e n t r a 1 f l o w ^ | l i n e • ( - f x j --fXr--<X--X>-I to m a n o m e t e r s F i g . 3.5b O r i f i c e p l a t e flowmeter assembly - 25 -F i g . 3.6 Picture of the experimental set-up. - 26 -Annulus gas v e l o c i t y measurements were provided by the s t a t i c pressure probe shown i n F i g . 3.7, the same probe as used by Lim (1975). The probe c o n s i s t s of two unequal lengths of s t a i n l e s s s t e e l tubing w i t h O.D. of 1.6 mm enclosed i n a l a r g e r s t a i n l e s s s t e e l tube housing of diameter 4.8 mm to provide r i g i d i t y and support. The two ends were f i t t e d w i t h 22 gauge hypodermic needles, bent at r i g h t angles 1.2 cm from the t i p s . The t i p s were v e r t i c a l l y separated by 2 cm. S t a t i c pressure drops were measured using an i n c l i n e d (15° with respect to h o r i z o n t a l ) manometer f i l l e d w i t h f l u i d of s p e c i f i c g r a v i t y 0.827. Minimum r e a d a b i l i t y was ± 0.5 mm on a l i n e a r s c a l e , which corresponds to a pressure drop of ± 0.11 mm H2O. 3.2 S o l i d Properties Three s o l i d m a t e r i a l s were used i n t h i s work: p o l y s t y r e n e , m i l l e t and high density polyethylene (HDPE). The m a t e r i a l s were i n i t i a l l y screened t o a r e l a t i v e l y narrow s i z e range before p a r t i c l e d e n s i t y , p a r t i c l e s i z e , bulk density and the l o o s e l y packed voidage were measured. 3.2.1 P a r t i c l e Shape and Size The HDPE p a r t i c l e s were n e a r l y s p h e r i c a l , while the polystyrene and m i l l e t p a r t i c l e s were assumed to be e l l i p t i c a l c y l i n d e r s and oblate spheroids, r e s p e c t i v e l y . Equivalent p a r t i c l e diameters were defined as the diameter of a sphere of the same volume as the p a r t i c l e . Two thousand p o l y s t y r e n e , seven hundred and f i f t y HDPE and three thousand m i l l e t p a r t i c l e s were separately weighed and t h e i r volumes measured by water displacement i n a 100 c.c. graduated c y l i n d e r . In the case of . - 27 -flat surface^-* of column 4.8 mm O.D diagram not to scale to inclined manometer — probe holder 120 cm 2 cm |*_^— 22 Gau ge 1.2 cm hypodermic needle F i g . 3.-7 Schematic diagram of the s t a t i c pressure probe - 28 -m i l l e t , which i s permeable to water, the p a r t i c l e s were f i r s t coated with a thin f i l m of Aeroplast^ dressing. P a r t i c l e dimensions for polystyrene and m i l l e t were also obtained by measuring the size of 20 p a r t i c l e s chosen at random for each material. Results obtained by the displacement method are used i n t h i s work. 3.2.2 Particle Density, Bulk Density and Loosely Packed Bed Voidage P a r t i c l e density was determined by means of pycnometer. The procedure for bulk density measurement used by Oman and Watson (1944), Eastwood et a l (1967) and Lim (1975) was adopted. A 500 c.c. graduated cylinder was p a r t i a l l y f i l l e d with a known weight of s o l i d p a r t i c l e s . The cy l i n d e r was covered at i t s open end and inverted, and then quickly returned to i t s o r i g i n a l upright p o s i t i o n . The volume occupied by the so l i d s at the end of t h i s procedure was taken as the bulk volume under loosely packed conditions. Five r e p l i c a t e s were taken to calculate the bulk density of the material. The v a r i a t i o n between separate tests was less than 1%. Voidage i n the loosely - packed bed condition was calculated from p a r t i c l e and bulk densities as follows: The re s u l t s obtained are presented i n Table 1. 1Brand name for a waterproof dressing made by Parke-Davis. - 29 -Table 1: Properties of S o l i d P a r t i c l e s used Material d P (cm) P s g/cm3 Pb g/cm3 £A Polystyrene 3.51 mm * 2.51 mm * 1.78 mm 0.285 1.04 0.59 0.43 M i l l e t 0.228 1.14 0.68 0.40 HDPE 0.394 0.93 0.58 0.38 - 30 -CHAPTER 4 CHOICE OF EXPERIMENTAL CONDITIONS 4.1 Points of Entry for Auxiliary Air Flow The d i s t r i b u t o r assembly allowed the a u x i l i a r y a i r to be supplied 5 i n thirty-two (2 ) d i f f e r e n t ways (incl u d i n g the case when there was no a u x i l i a r y flow). However, only three configurations were used. Configuration #1 - A u x i l i a r y a i r was supplied at a l l l e v e l s ( i . e . at each of the f i v e subdistributors shown i n Figures 3.3c and 3.4). Configuration #2 - A u x i l i a r y a i r was supplied through the upper two chambers only. Configuration #3 - A u x i l i a r y a i r was supplied through the two lowest chambers only. For each configuration, the a i r flow to each chamber was adjusted i n proportion to the number of openings from that calming chamber. In other words, the a i r v e l o c i t y through each opening was the same for a l l chambers that were i n operation. The above configurations represented the normal case (configuration #1) and two extreme cases (configuration #2 & #3). 4.2 Central Flow and Auxiliary Flow Combination Proper choice for combinations of the c e n t r a l flow and a u x i l i a r y flow for spouting with aeration was d i f f i c u l t without knowing how the various flow regimes depended on these flows. Therefore, regime maps were f i r s t obtained so that appropriate flow combinations could be selected. - 31 -CHAPTER 5 REGIME MAPS AND MINIMUM FLUID FLOWRATE FOR SPOUTING WITH AERATION AND SPOUT FLUIDIZATION 5.1 Experimental Technique Two methods were used to obtain the flow regimes Method #1 - The central a i r flow was increased/decreased continuously while maintaining the a u x i l i a r y a i r flow constant. Method #2 - The a u x i l i a r y a i r flow was decreased/increased stepwise while maintaining the cent r a l a i r flow constant. Several i n i t i a l t r i a l runs were made. It was found that the flow regimes were quite d i s t i n c t and could be i d e n t i f i e d v i s u a l l y . Moreover, the t r a n s i t i o n from one regime to another was accompanied by either a sudden increase/decrease i n bed pressure drop or increase/decrease i n the magnitude of pressure drop f l u c t u a t i o n . These observations thus formed the basis for di s t i n g u i s h i n g the d i f f e r e n t flow regimes. 5.1.1 Transition From Spouting with Aeration to  Fluidized Bed or Fixed Packed Bed For a given bed height,* bed material and i n l e t o r i f i c e diameter, spouting was i n i t i a l l y obtained by supplying s u f f i c i e n t c e n t r a l spouting a i r . The a u x i l i a r y flow was then supplied and maintained constant while *Bed height was measured to the top of the annulus under spouting conditions at a spouting flowrate of 1.1 Qms. - 32 -the central a i r flow was gradually decreased (method #1) u n t i l a point was reached where a sudden increase i n bed pressure drop and the collapse of the spout were noted. This point, was taken as the condition for minimum spouting with aeration. If Q m s > Qmf, f l u i d i z a t i o n of the upper bed s o l i d material was obtained a f t e r the t r a n s i t i o n : on the other hand, i f Q < Q c , d i r e c t t r a n s i t i o n to f i x e d ' ' m^s T o f ' packed bed conditions was obtained. The a u x i l i a r y flow was supplied i n the range from no flow to a value where f l u i d i z a t i o n of the upper bed annular s o l i d s was attained. Thus, a set of points representing the r e l a t i v e influences of central and a u x i l i a r y flows was established. 5.1.2 Transition from Spouting with Aeration  to Spout Fluidization In t h i s case, method #2 was employed. Spouting was established i n i t i a l l y , the central a i r flow was then kept constant while the a u x i l i a r y flow was increased stepwise. Two situ a t i o n s were observed: (I) I f the a u x i l i a r y flowrate was increased stepwise, a point was reached where spout i n s t a b i l i t y was obtained. This marks the onset of spout f l u i d i z a t i o n as described already i n Section 2.1.1 ( i v ) . The t r a n s i t i o n was accompanied by f l u c t u a t i o n of bed pressure drop. The a u x i l i a r y flow for t h i s t r a n s i t i o n was denoted as q*. (II) If the a u x i l i a r y flowrate was increased stepwise and, at each step, the column was manually given a shake or two, the bed would behave i n one of two d i f f e r e n t ways: - 33 -( i ) spout i n s t a b i l i t y was attained at an a u x i l i a r y flowrate q** which was lower than q*. The spout would remain unstable. ( i i ) Spout i n s t a b i l i t y was attained at an even lower a u x i l i a r y flowrate, q***, but s t a b i l i t y was restored immediately. I t was apparent that under condition I I ( i ) i n the absence of shaking, the bed was i n a state of pseudo-stability provided that q** < q < q*, where q*** < q** < q* Therefore, the t r a n s i t i o n point was taken as the maximum value of q*** or minimum value of q** at which i n s t a b i l i t y could not be sustained. Several i n i t i a l spouting flowrates i n the range of 1.0 Q m s to 1.4 Q m s were used to obtain d i f f e r e n t experimental points. It was found that at an a u x i l i a r y flowrate of q**, spout i n s t a b i l i t y could also be attained, even without any physical disturbance, i f the bed was kept at t h i s condition f o r several minutes. The ph y s i c a l disturbance only provided a fa s t e r t r a n s i t i o n to i n s t a b i l i t y . 5.1.3 Transition from Spout-fluidization  to Jet i n Fluidized Bed A u x i l i a r y a i r was introduced to a spouted bed u n t i l s p o u t - f l u i d i z a t i o n was obtained as described i n the previous section. Once t h i s state was attained, the cen t r a l a i r flow was decreased slowly and the bed was observed to gradually undergo a t r a n s i t i o n state where the condition of slugging* and s p o u t - f l u i d i z a t i o n alternated. A point *The term slugging as used here refers to the condition of a submerged j e t i n f l u i d i z e d bed with slugging of the s o l i d material i n the upper section of the bed. Please r e f e r to section 5.2 for greater d e t a i l . - 34 -was reached, upon further reducing the c e n t r a l a i r flow, where the bed was i n a completely slugging mode. The t r a n s i t i o n was accompanied by an increase i n the magnitude of pressure f l u c t u a t i o n due to the r i s i n g and col l a p s i n g of the bed surface as slugs break through. 5.2 Results and Discussion 5.2.1 Regime Maps; A t y p i c a l phase diagram i s shown i n F i g . 5.1. The ordinate and abscissa denote the a u x i l i a r y flowrate and c e n t r a l flowrate normalized with respect to minimum f l u i d i z a t i o n flowrate, Q mf. The t r a n s i t i o n points determined, based on the c r i t e r i a described i n Section 5.1, have been used to define the boundaries of the various flow regimes. Four f a i r l y d i s t i n c t flow regimes have been delineated: Spouting with aeration (SA), S p o u t - f l u i d i z a t i o n (SF), Submerged j e t i n f l u i d i z e d bed ( J F ) , and Packed bed (P). The physical appearance of these flow regimes i s shown i n F i g . 5.2. For the j e t i n f l u i d i z e d bed regime there were two states of f l u i d i z a t i o n . At higher a u x i l i a r y flow, slugging of the s o l i d material i n the upper section of the bed was observed, with a slugging frequency of the order of one to two Hz, s i m i l a r to that i n conventional slugging. This state was denoted as J F ( I ) . At lower a u x i l i a r y flows a subregime, designated J F ( I I ) , was noted where bubbles broke the bed surface. The t r a n s i t i o n between JF(II) and JF(I) was gradual and could - 35 -qcj/Qmf 1.6 • Observed spout-f l u i d i z a t i o n o Observed spouting with aeration 1.4 1.2 1.0 0 .8 0.6 0.4 0.2 Je t in f l u i d i z ed bed ( s l u g g i n g ) J H I ) / Spout-f lu id i za t ion ( S F ) \ \ \ \ N A Spout ing with \ J F ( I I ) \ ^ aerat ion ( S A ) Pa cked bed ( P ) \ \ { b u b b l W j ) o 0 0.2 .0.4 0.6 0.8 1.0 1.2 1.4 Q/Qmf F i g . 5.1 Regime map [system: polystyrene, d = 1.91 cm, H= 60cm] Poi n t s d e s i g n a t i o n : G - F l u i d i z a t i o n at minimum c o n d i t i o n A - Spouting at minimum c o n d i t i o n C - Co-ordinates f o r spout-f l u i d i z a t i o n at minimum c o n d i t i o n , i . e . (_j\nsa) and ( ^ msa ) . r e s p e c t i v e l y . „ c max — — - — mm 3 Qmf Qmf F i g . 5.2 Physical appearance of various flow regimes [ (P)- fixed pa eked...-bed, (SA)- spouting with aeration, JF(I) & J F ( I I ) - submerged j e t in f l u i d i z e d bed, (SF)- s p o u t - f l u i d i z a t i o n , (T)- t r a n s i t i o n between JF(I) and (SF)] - 37 -not be established from measurement of the changes i n pressure drop. No annular s o l i d s movement was observed for J F ( I I ) . However, for the JF(I) state, s o l i d s mixing resulted from the p e r i o d i c r i s e and f a l l of the slugs. In s p o u t - f l u i d i z a t i o n , stable spouting was not achieved. The annular s o l i d s at the upper section of the bed were being f l u i d i z e d . The spout diameter near the bed surface appeared to shrink and expand i n a periodic manner. However, on closer examination by means of a Strobotac* and Super-8 mm movie f i l m taken at 64 frames per second, the spout was observed to be not continous; instead i t broke into large bubbles near the bed surface. For m i l l e t , the formation of the bubbles occurred much e a r l i e r , extending from a few centimeters above the i n l e t o r i f i c e p l a t e . The "spout" was i n fact a succession of r i s i n g bubbles. The frequency of bubble break-up at the bed surface determined by the Strobotac was found to be i n the range of 6 to 7 Hz. A s i m i l a r range was also determined by H e i l (1983) and by Rowe (1983). The p e r i o d i c formation of bubbles caused the spout to appear to fluctuate i n diameter. The appearance of t h i s regime i s shown i n F i g . 5.3. The shape and structure of the fountain was e n t i r e l y d i f f e r e n t from that observed for stable spouting. The fountain was formed by s o l i d s material p e r i o d i c a l l y ejected by the bursting bubbles. A maximum height was achieved at the burst of the r i s i n g bubbles and a minimum immediately thereafter. Therefore, the height of the fountain o s c i l l a t e d between a maximum and a minimum value with the same frequency *Trade name for strobe l i g h t generator. - 39 -as the frequency of bubble eruption. (See F i g . 5.3). The movement of annular s o l i d s near the bed surface assumed a s l i p - s t i c k type behaviour, and the s o l i d s movement gradually became more continuous with decreasing height. The behaviour of s p o u t - f l u i d i z a t i o n was s i m i l a r to that•of a standard spouted bed whose height equals the maximum spoutable bed depth. The t r a n s i t i o n from s p o u t - f l u i d i z a t i o n to submerged j e t i n f l u i d i z e d bed of the type JF(1) was gradual. On decreasing the c e n t r a l flow, the frequency of bubble formation decreased. This allowed bubbles to grow larger i n size before reaching the bed surface. A further decrease of ce n t r a l flow resulted i n bubbles whose size was equal to or greater than the column diameter, and slugging of the upper bed material was thereby obtained. The t r a n s i t i o n between these two regimes i s i l l u s t r a t e d for m i l l e t and polystyrene i n Figure 5.4, and i s also shown as t r a n s i t i o n state (T) i n F i g . 5.2. The sequence of t r a n s i t i o n from s p o u t - f l u i d i z a t i o n to submerged j e t i n f l u i d i z e d bed of the type JF(I) i s shown i n F i g . 5.5. Regime maps of other workers discussed i n Chapter 2 were determined from experiments i n f u l l columns. The v i s i b l e c h a r a c t e r i s t i c s of the spout were found to be d i s t i n c t i n each flow regime i n the present half-column work. The i n a b i l i t y of previous workers to observe changes i n spout shape between the d i f f e r e n t regimes no doubt contributed to d i f f i c u l t i e s i n i n t e r p r e t i n g flow behavior. V i s u a l observation and pressure drop measurement were of equal importance i n the present work. The half-column geometry thus provided important observations which m i l l e t polystyrene F i g . 5.4 T r a n s i t i o n state between s p o u t - f l u i d i z a t i o n and submerged j e t in f l u i d i z e d bed of the type JF(I) i r • • I Q = 2.5 1/s Q = 3.5 1/s submerged j e t i n f l u i d i z e d bed <: Q = 4.0 1/s , Q = 4.5 1/s s p o u t - f l u i d i z a t i o n F i g . 5.5 T r a n s i t i o n from s p o u t - f l u i d i z a t i o n to submerged j e t i n f l u i d i z e d bed of the type JF (I) [ p o l y s t y r e n e , a = 4.5 1/s) a - 42 -would have been impossible i n a f u l l column. Regime maps are shown i n Figures 5.1 and Figures 5.6 through 5.13 f o r the various systems i n v e s t i g a t e d . The h y p o t h e t i c a l phase diagram of F i g . 2.2 p r e d i c t e d the existence of these flow regimes f a i r l y w e l l . The three m a t e r i a l s s t u d i e d y i e l d e d s i m i l a r patterns (Figures 5.1 and Figures 5.6 through 5.13). The l i n e A-C has a negative slope greater than one, i n d i c a t i n g that the sum of a u x i l i a r y and c e n t r a l flow necessary f o r spouting w i t h a e r a t i o n i s great e r than that r e q u i r e d f o r spouting i n a standard spouted bed. This i n d i c a t e s a modified f l u i d flow p a t t e r n i n the bed, w i t h a greater p o r t i o n of the t o t a l f l u i d passing through the annular s o l i d s as the prop o r t i o n of a u x i l i a r y flow i s increased. In a l l cases l i n e B-E has a p o s i t i v e slope which i n d i c a t e s that p e n e t r a t i o n of the spout through the bed surface i n a f l u i d i z e d s t a t e r e q u i r e s greater c e n t r a l spouting flow; otherwise, slugging i s achieved. Polystyrene p a r t i c l e s , which have an e l l i p t i c a l c y l i n d r i c a l shape, show a greater tendency to i n t e r l o c k and bridge. They are thus more l i k e l y to show slugging behaviour. This i s r e f l e c t e d i n the sma l l e r slope of l i n e B-E compared w i t h those f o r m i l l e t and HDPE. The t r a n s i t i o n p o i n t s separating s p o u t - f l u i d i z a t i o n and spouting w i t h a e r a t i o n were obtained at the highest p o s s i b l e a u x i l i a r y flow that does not cause f l u i d i z a t i o n of the annular s o l i d s at the bed surface. For polystyrene p a r t i c l e s , the boundary shown by l i n e C-D has an i n i t i a l slope of zero and the slope becomes greater than zero w i t h i n c r e a s i n g c e n t r a l flow. Slopes of the l i n e C-D f o r both HDPE and m i l l e t p a r t i c l e s are always greater than zero. A s i m i l a r trend was noted by Littman (1982), Chatterjee (1974) and Dumistrescu (1977). This may occur - 43 1.6 1.2 0.8 0.4 r 0 -1 L 10 0 OA. 0.8 1.2 1.6 Q/Qmf F i g . 5.6 Regime map [system: polystyrene, d\= 1.91 cm, H= 30 cm] 1.6 1 6 2 0 Q/Qmf F i g . 5.7 Regime map [system: polystyrene, d^= 1.91 cm, H= 45 cm] 1.6 2.0 Q/Qmf F i g . 5.9 Regime map [system: HDPE, d = 1.91 cm, H= 35 cm] E a o cr 0.4 0.8 1.2 1.6 2.0 Q/Qmf F i g . 5.10 Regime map [system: m i l l e t , d = 1.91 cm, H= 30 cm] 1.6 2.0 Q/Qmf F i g . 5.11 Regime map [system: m i l l e t , d_^ = 1.91 cm, H= 45 cm] - 46 -1.6 2.0 Q/Qmf Fig. 5.12 Regime map [system: polystyrene, H= 45 cm , d.= 2.54 cm] a S- 1.2 0 0.4 0.8 1.2 1.6 2.0 Q / Q m f F i g . 5.13 Regime map [system: m i l l e t , H= 30 cm, d\= 2.54 cm] - 47 -because there i s a decrease of annulus gas v e l o c i t y for an increasing central flow, (Lim (1975)), so that more a u x i l i a r y flow can be introduced before s p o u t - f l u i d i z a t i o n i s achieved. Spouting with aeration, as far as i t s v i s i b l e c h a r a c t e r i s t i c s are concerned, i s s i m i l a r to spouting i n a standard spouted bed. This regime i s stable and the extent of th i s regime depends on several f a c t o r s . The regime area for polystyrene was greater than for HDPE and m i l l e t . HDPE and m i l l e t p a r t i c l e s both have very low maximum spoutable bed height - H m of 45 and 48 cm resp e c t i v e l y for an o r i f i c e diameter of 1.91 cm - whereas the corresponding H m for polystyrene p a r t i c l e s i s 90 cm. With a greater o r i f i c e diameter, d^ = 2.54 cm, the l i n e A-C s h i f t s a l i t t l e to the r i g h t , since a greater minimum spouting flow i s then required [see Figures 5.12 and 5.13]. An increased o r i f i c e diameter re s u l t s i n a lower H value. This i n m turn reduces the regime area f o r spouting with aeration. The value of H m has a strong effect on this regime area. For the case of m i l l e t and q ins 9. HDPE at d. = 2.54 cm, t h i s regime i s so r e s t r i c t e d that ( — — ) i s l 6 Q -max mf less than 0.2, a value too low to accurately monitor the a u x i l i a r y flow. For this reason, determination of annulus gas v e l o c i t y , s o l i d c i r c u l a t i o n , fountain height, pressure drop and spout diameter could not be accomplished for m i l l e t and HDPE. 5.2.2 Minimum F l u i d Flowrate; The experimental data plotted as l i n e A-C i n F i g . 5.1 and F i g . - 48 -5.6 through F i g . 5.13 showed that the minimum t o t a l f l u i d flow rate followed a l i n e a r r e l a t i o n s h i p and can be represented by i _ / m t \ / msa> Q Q * ms mf (5.1) This l i n e a r equation terminates at point C due to the formation of another flow regime. Equation (5.1) i s therefore v a l i d f o r q Q ,nmsa. . ,nmsa, Qmf Qmf - X (5.2) Q Q .jrnsa. . /msav Qmf Qmf ^ (5.3) values for Q m g and were determined experimentally. T o t a l minimum f l u i d flow at a given bed height under t h i s condition, noting Equation (2.5), i s then given by QT'msa  Qmf = K + ms Qm sa (5.4) "mf E a r l i e r work by Vukovic (1972) and Littman (1974, 1976) indicated that ^msa^ _ j _ ^mf Qms a j ^mf Qms Qmf - 49 -Eq. (2.4) was v a l i d for < and i t also showed that the sum of ce n t r a l flow and a u x i l i a r y flow for spouting with aeration l i e s between Q and Q c i . e . ms mf Qms < Vmsa < Qmf However, for Q m g > Q mf, the apparent intercept on the ordinate q a 0 axis of l i n e A-C on a plot of (——) versus (77*—) of Figure 5.1 and qmf gmf Figures 5.6 through 5.13 was found to be always greater than unity. Equation (5.1) i s therefore an improvement over the o r i g i n a l equation (2.4) i n incorporating a parameter K to account both for cases where < and > Q^. The values of K and the slopes of the l i n e A-C for the various runs are summarized i n Table 2. Since the slope i s greater than unity i n a l l cases, i t i s confirmed that the sum of the a u x i l i a r y flow and cen t r a l flow required for spouting with aeration i s always equal to or greater than the minimum spouting v e l o c i t y , even when Qfflg > From Table 2, values of the slope for a given material appear to be i n s e n s i t i v e to bed height and to i n l e t o r i f i c e diameter. The coordinate of point C i s the l i m i t i n g value for spouting with aeration, and i s the minimum condition for s p o u t - f l u i d i z a t i o n . The sum q Q_ IH Sci TI1S3. of ( — — ) and ( — r — ) . equals the normalized minimum f l u i d flowrate Qmf m a X Qmf m ± n f o r s p o u t - f l u i d i z a t i o n , and at t h i s condition, the given bed height i s termed the "maximum bed height for s p o u t - f l u i d i z a t i o n " , H c . H c ' msr msf d i f f e r s from the maximum spoutable bed height, H m, i n i t s dependence on - 50 -Table 2: Values of Empirical Constant K and Slopes of the Line A-C for Diff e r e n t Systems Investigated. M a t e r i a l H (cm d i (cm) Slope K Polystyrene 30 1.91 1.30 1.27 Polystyrene 45 1.91 1.27 1.38 Polystyrene 60 1.91 1.25 1.47 HDPE 30 1.91 1.28 1.46 HDPE 35 1.91 1.24 1.52 M i l l e t 30 1.91 1.54 1.39 M i l l e t 45 1.91 1.77 1.75 Polystyrene 45 2.54 1.29 1.50 M i l l e t 30 2.54 1.36 1.61 - 51 -q •msa the value of ( I? 0 0) . In other words, every bed height could be U max ms q termed as H , at a given ( — — ) . msf Q 'max mf q Q Values of (- ) and (— ) . appear i n Table 3. As shown i n Qmf m a x Qmf ^ q Table 3, the value of (— ) appears to be s e n s i t i v e to H . Q c max r r m mf Polystyrene p a r t i c l e s having a high value of H , has a higher (- ) m Q _ max mf than HDPE and m i l l e t , which have much lower value. Equation (5.1), together with Equations (5.2) and (5.3), provide an easy means for estimating the minimum f l u i d flowrate for spouting with aeration. However, general correlations encompassing a wide range of experimental data under various conditions are needed for estimation q Q of K, (-SS&) and (-22£) . Qmf m a x Qmf ^ Table 3: Normalized Values of Central and A u x i l i a r y Flow at Minimum Spout-Fluidization Conditions and the Maximum Spoutable Heights for the Systems Investigated. M a t e r i a l H (cm) d i (cm) Q , "max mf z^msa^ Qmf m i n H m (cm) Polystyrene 30 1.91 0.75 0.40 90 45 1.91 0.83 0.45 60 1.91 0.78 0.56 HDPE 30 1.91 0.30 0.91 45 35 1.91 0.30 0.99 M i l l e t 30 1.91 0.40 0.65 48 45 1.91 0.20 0.87 Polystyrene 45 2.54 0.54 0.74 80 M i l l e t 30 2.54 0.18 0.88 36 - 53 -CHAPTER 6 LONGITUDINAL ANNULAR GAS VELOCITY AND OVERALL BED PRESSURE DROP FOR SPOUTING WITH AERATION 6.1 Measurement Technique 6.1.1 Longitudinal Annular Gas Velocity: Annular gas flow i n the c y l i n d r i c a l section was determined from measurement of the v e r t i c a l s t a t i c pressure gradient along the annulus. Lim (1975) found that t h i s measurement technique was r e l i a b l e . The s t a t i c pressure probe shown i n F i g . 3.7 was supported from above half-way between the spout-annulus interface and the column wa l l . No s i g n i f i c a n t r a d i c a l pressure gradient was found i n the c y l i n d r i c a l section. The l o n g i t u d i n a l positions of the probe extended from 2 cm below the bed surface to the c y l i n d r i c a l - c o n i c a l j u n c t i o n . Measurements were taken at 10 cm i n t e r v a l s , reduced to 5 cm near the c o n i c a l - c y l i n d r i c a l junction due to a more rapid change i n v e r t i c a l gas v e l o c i t y i n t h i s section. Gas flow measurement i n the coni c a l section was complicated by the uncertainty i n the voidage of t h i s section. It i s generally accepted that the voidage i n this section i s lower due to p a r t i c l e s r e a l i g n i n g and compacting as they move downward ( E l j a s (1975)). Gas flow i n the conical region was not determined i n t h i s work. The s t a t i c pressure technique r e l i e s on the assumption that the state of the annulus i s the same as i n a loosely packed bed of the same material. The s t a t i c pressure gradient i n a loosely packed bed i s a function of the gas v e l o c i t y . For a given s o l i d material, a c a l i b r a t i o n - 54 -curve of s t a t i c pressure gradient versus gas v e l o c i t y obtained i n a loosely packed bed was used i n t h i s work to determine the l o c a l gas v e l o c i t y i n the annulus. Ca l i b r a t i o n s were obtained i n the same half-column with bed height greater than the maximum spoutable bed height, Hm. Measurements made at two r a d i a l l y d i f f e r e n t positions showed that there was i n s i g n i f i c a n t r a d i a l v a r i a t i o n of s t a t i c pressure drop. The c a l i b r a t i o n r e s u l t s are summarized i n Appendix I. 6.1.2 Overall Bed Pressure Drop An i n c l i n e d U-tube manometer f i l l e d with l i q u i d of s p e c i f i c gravity 0.827 provided the measurement of o v e r a l l bed pressure drop. The f r i c t i o n a l pressure drop due to p a r t i c u l a t e material at a given mass flowrate was obtained by the procedure proposed by Epstein and Mathur (1974). For the pressure tap located upstream of the i n l e t o r i f i c e plate, p o s i t i v e values of s o l i d s - f r e e pressure drop were obtained with increasing c e n t r a l a i r flow. On the other hand, negative values of s o l i d s - f r e e pressure drop were obtained for the pressure tap located at the o r i f i c e plate i t s e l f . Since the f r i c t i o n a l pressure drop i s a p o s i t i v e quantity, the ca n c e l l i n g e f f e c t with the negative s o l i d s - f r e e pressure drop r e s u l t s i n a narrower range of manometer f l u i d l i n e a r t r a v e l , allowing l i g h t e r s p e c i f i c gravity f l u i d s to be used. Thus r e a d i b i l i t y was enhanced. In t h i s work, only readings from the pressure tap located at the o r i f i c e plate were used. 6.2 Results and Discussion 6.2.1 Longitudinal Annular Gas Velocity: Figure 6.1 shows that the s u p e r f i c i a l gas v e l o c i t y i n the annulus 7 0 •«!! E o < 6 0 5 0 4 0 3 0 2 0 1 0 r 0 SOLIDS * By Lim (1975) with 0 VO =1.2 2 ~T ms ** " . = 1.3 • HDPE 0 O " • Q24 • Polystyrene 0 A 0.31 <| ' • » 0.47 • Polystyrene* 0 k ** 0 o 1 0 2 0 3 0 4 0 H, cm 35 60 45 5 0 6 0 - Z , c m F i g . 6.1 Ef f e c t of a u x i l i a r y gas flow on annulus gas s u p e r f i c i a l v e l o c i t y .[ Q T / = 1.25, d.= 1.91 cm ] - 56 -increased with bed l e v e l and that the increase was more rapid i n the lower section. A comparison with r e s u l t s of annulus s u p e r f i c i a l gas v e l o c i t y obtained by Lim (1975) i s also shown i n F i g . 6.1. The difference between his res u l t s and the r e s u l t s obtained i n t h i s work i s probably due to differences i n the dimensions and geometry of the polystyrene p a r t i c l e s used. Annulus gas v e l o c i t y was also found to increase with increasing a u x i l i a r y flow. The increase was more subs t a n t i a l at the lower section of the annulus. The percentage increase of annulus gas v e l o c i t y due to a u x i l i a r y flow i s shown i n F i g . 6.2. As much as a f i f t y percent increase could be r e a l i z e d near the c o n i c a l - c y l i n d r i c a l junction when the a u x i l i a r y flow comprised h a l f of the t o t a l flow supplied. I t was noted, however, that the percentage increase due to a u x i l i a r y flow r a p i d l y dropped off with increasing bed l e v e l . The results indicate that a d d i t i o n a l external f l u i d supplied d i r e c t l y into the annulus of a standard spouted bed can be accommodated without upsetting the basic behaviour of spouting. However, there i s a l i m i t to how much a u x i l i a r y flow can be introduced before spout i n s t a b i l i t y sets i n r e s u l t i n g i n s p o u t - f l u i d i z a t i o n . Figure 6.3 shows that, as i n a standard spouted bed, the annulus gas v e l o c i t y at a given bed l e v e l was independent of the o v e r a l l bed height. A plot of U^/Uj^jjjjj versus Z/H i s shown i n Figure 6.4. The values of were obtained by extrapolating to H^. I t was found that at H , U._T < U ,, a result reported e a r l i e r by Lim (1975). Experimental m AHm ml data were compared with the only e x i s t i n g equation derived by Littman (1976) f or a flat-base column, Eq. 2.10. However, U mf i s replaced by SOLIDS H,cm r a Z/H 6.2 Percent increase of annulus gas v e l o c i t y due to a u x i l i a r y flow [ Q^ , / CL s = 1.25, d^= 1.91 6 0 e 5 0 - 4 0 < 3 3 0 2 0 1 0 0 L 0 1 0 • A o A1 • • o H,cm 60 45 A o 2 0 3 0 4 0 a 38 0 0.40 0 5 0 6 0 Z , c m F i g . 6.3 Annulus gas s u p e r f i c i a l v e l o c i t y for d i f f e r e n t heights [system: polystyrene, d^= 1.91 cm, co Z/H F i g . 6.4 Relationship between U /U and Z/H for d i f f e r e n t values of r [ d.= 1.91 cm ] - 60 -U AHm at Z=H so that Equation (2.10) becomes u A(z) (6.1) AHm For q/Q^ = °» equation (6.1) reduces to the modified Mamuro H a t t o r i equation, The maximum bed height f o r s p o u t - f l u i d i z a t i o n i s always smaller or equal to the maximum spoutable bed depth, i . e . H c < H . (Values of H are msr — m m given i n Table 3 ) . I f H m s f Is replaced by HJJJ, equation 6.1 i s found to c o r r e l a t e the data f o r polystyrene p a r t i c l e s w i t h H = 60 cm ( h m s f = h = 0.67) q u i t e w e l l but underpredicts the data f o r HDPE p a r t i c l e s w i t h H = 35 cm ( h m s f = h = 0.78). However, at H ^ / I L ^ - 0.92 or \ s f = 0.85, a b e t t e r f i t i s achieved f o r HDPE p a r t i c l e s . In Figure 6.5, the assumption of H c = H or h c = 0.75 again c msr m msf caused Equation 6.1 to underpredict the data. At H -/H = 0.83 or h _ r msf m msf = 0.90, however, Equation 6.1 produces a b e t t e r f i t . For the systems i n v e s t i g a t e d , the r e l a t i o n s h i p between maximum bed height f o r s p o u t - f l u i d i z a t i o n and i n l e t o r i f i c e diameter and a u x i l i a r y flow could not be e s t a b l i s h e d . Therefore the assumption of H j being independent of a u x i l i a r y flow f o r the cases s t u d i e d i s a l s o subjected to e r r o r . I t i s apparent that ^msf i s an adjus t a b l e parameter whose value needs to be i n t e r p r e t e d more p r e c i s e l y . Furthermore, the equation f o r H (Littman - 1 - (1 - Z/H m) 3 (6.2) 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 Z/H F i g . 6.5 R e l a t i o n s h i p between U./U , and Z/H f o r d i f f e r e n t values of r [ d =2.54 cm. H= 60 cm ] A AHm a l - 62 -1976, 1983) was derived based on a flat-base column. The a p p l i c a b i l i t y of such an equation may be acceptable for pr e d i c t i n g the annulus gas v e l o c i t y p r o f i l e of the c y l i n d r i c a l part but not the con i c a l part of the present column. The e f f e c t of a u x i l i a r y gas entry p o s i t i o n on annulus gas v e l o c i t y i s shown i n Figure 6.6. Configuration #2 (see Section 4.1) was found to y i e l d greater annulus gas v e l o c i t y than configuration #3. In configuration #3, for which the a u x i l i a r y flow entry p o s i t i o n was close to the spout, the observed lower annulus gas v e l o c i t y was l i k e l y due to gas bypassing d i r e c t l y into the spout. The e f f e c t of i n l e t o r i f i c e diameter on annulus gas v e l o c i t y i s shown i n F i g . 6.7. As i n standard spouted beds, the greater the o r i f i c e plate opening, the greater the portion of spouting gas which flows into the annulus, thereby contributing to greater o v e r a l l annulus gas v e l o c i t y . The e f f e c t of increasing the f r a c t i o n of a u x i l i a r y flow on the annular gas flow at d i f f e r e n t bed l e v e l s i s shown i n F i g . 6.8. The f r a c t i o n of gas flowing through the annulus increases almost l i n e a r l y with an increase of a u x i l i a r y flow. The t o t a l flow i n the annulus was always found to be greater than the a u x i l i a r y flow supplied i n d i c a t i n g that there i s no net cross-flow of f l u i d from the annulus to the spout i n the c y l i n d r i c a l section for the conditions studied. However, for configuration #3, the tendency of f l u i d cross-flow from the annulus to the spout may be high, e s p e c i a l l y i n the cone region near where the a u x i l i a r y flow i s being introduced. 0 0 0.1 0.2 0.3 OA Q 5 0.6 0 7 0 8 Z/Hm F i g . 6.6 Relationship between \] /Umf and Z/H for d i f f e r e n t a u x i l i a r y gas flow entry configurations [ polystyrene, d ±= 2.54 cm, H= 60 cm, QT/Q^ •=• 1.25] Z/Hm F i g . 6.7 Relationship between U /U and Z/H for d i f f e r e n t i n l e t o r i f i c e diameters [ polystyrene, H= 60 cm, ^T^ms" 1 ' 2 5 1 0 0.125 0.250 Q375 Q500 0.625 0.750 F i g . 6.8 E f f e c t of the f r a c t i o n of a u x i l i a r y flow on the f r a c t i o n of gas which flows through the annulus ( polystyrene, H= 60 cm, d_. = 1.91 cm, QT= 8 1/s ) - 65 -6.2.2 O v e r a l l Bed Pressure Drop The pressure gradient f o r an i n c i p i e n t l y f l u i d i z e d bed having voidage i s given by " § = <PB " " eA>« ( 6 ' 3 ) The pressure drop per unit bed height for the present experiments was f i t t e d by H = f(U) (6.4) where f(U) i s a 5th order polynomial given i n Appendix I. Under minimum f l u i d i z a t i o n condition, Equation 6.4 becomes AP ^ i = f < U m f > <6'5> Values of ( p s - p ) ( l - E A ) and f ( U m f ) are shown i n Table 4. It i s seen that f ( U m f ) < ( p s - p ) ( l - eA)g- Values of o v e r a l l pressure drop for spouting with aeration normalized with respect to A P s pressure drop for f l u i d i z e d bed i . e . (._ ) are plotted versus q /Q _ AP ^ ' msa mf i n Figure 6.9 for the various systems investigated. Comparison of the o v e r a l l pressure drop data was made with equation 2.22 with d i f f e r e n t hjjjgf values. The data indicate that o v e r a l l pressure drop shows a l i n e a r r e l a t i o n s h i p with qmsa/Qmf. and the rate of increase i s not as rapid as predicted by Eq. 2.22. Furthermore, extrapolation of these data to q m s a/Qnif = 1 do not coincide with the ordinate equal to unity as i s predicted. P h y s i c a l l y , for (q/Q ,,) > (q /Q ,.) the mf msa mf max bed i s i n the submerged j e t i n f l u i d i z e d bed regime. This seems to indica t e that d i f f e r e n t c o r r e l a t i o n s may be required to treat each regime separately. - 66 -Table 4: Comparison of the Values of (p g - p ) ( l - e^) g and f ( U m f ) M a t e r i a l § - ( p s - p ) ( l - £ A ) g (mm H20/m) A P f (AH > - « D » f > (mm ^O/m) ^ f / A H ( P s - p ) d - e A ) g Polystyrene 594 445 0.75 HDPE 578 488 0.84 M i l l e t 6.86 650 0.95 ( A P s / A P f ) msa 1.0 h m s f = 1.75 - 67 -0.2 0.1 0 d; .mm H,cm A u x i l i a r y f l o w conf i g u r a t i o n • • A • A 2.54 E q . 2.22 45 60 30 45 60 1 2 3 1 1 2 3 1 1 1 0 0.2 0.4 0.6 0.8 1.0 Clmsa/Qmf F i g . 6.9 Relationship between (Ap~/AP.) and q /Qmf f o r d i f f e r e n t s f msa nmsa i n l e t o r i f i c e diameters, bed heights and a u x i l i a r y flow c o n f i g u r a t i o n [polystyrene] - 68 -CHAPTER 7 PARTICLE VELOCITY IN THE ANNULUS 7.1 Measurement Technique P a r t i c l e v e l o c i t y i n the annulus was determined by v i s u a l l y following and timing a marked p a r t i c l e s at the annulus wall i n t e r f a c e over a distance of 10 cm, s t a r t i n g at 5 cm below the bed surface. P a r t i c l e v e l o c i t y was found to vary at d i f f e r e n t positions along the perimeter of the column. I t was found to be lowest at the junction of the f l a t front surface and the curved surface. This was p r i m a r i l y caused by the wall e f f e c t due to the convergence of the two surfaces. To minimize t h i s problem and simulate full-column behaviour, measurements were made near the mid-section of the curved surface, f a r from the junctions. Under s p o u t - f l u i d i z a t i o n , movement of p a r t i c l e s i n the upper part of the annulus was of a s t i c k - s l i p type and this measurement method could not be employed r e l i a b l y . At deeper bed heights, the fountain was observed to sway from side to side, a f f e c t i n g the continuity of p a r t i c l e movement i n the annulus. The s i t u a t i o n was corrected by placing an inverted half-funnel at the top of the fountain. 7.2 Results and Discussion The s o l i d mass c i r c u l a t i o n rate i s expressed as Sr = A A * V p * (1 - e A ) * p s (7.1) with e A and p being constants for a given material. For spouting with A S aeration, the changes i n spout cross-sectional area i n the upper section - 69 -of the bed were found to be i n s i g n i f i c a n t compared with the annulus cro s s - s e c t i o n a l area. The maximum percentage change i n the annulus c r o s s - s e c t i o n a l area was less than 3% for d i f f e r e n t c e n t r a l and a u x i l i a r y flow combinations. P a r t i c l e v e l o c i t y was therefore used as a representation of the o v e r a l l s o l i d s c i r c u l a t i o n rate i n the bed. P a r t i c l e v e l o c i t y was found to increase with bed height as shown i n F i g . 7.1. This occurs because for a deeper and longer spout, there i s a greater p o s s i b i l i t y of p a r t i c l e s being entrained at the spout-annulus interface and c a r r i e d over into the fountain where they r a i n back onto the annulus. The e f f e c t of a u x i l i a r y flow on p a r t i c l e v e l o c i t y at various bed heights i s shown i n F i g . 7.2. For deeper beds, there was an increase of p a r t i c l e v e l o c i t y with an increase of a u x i l i a r y flow. However, for shallower beds, the reverse was found to be true. One possible explanation f o r the observed e f f e c t at shallow bed height i s that the sizeable increase of annulus gas v e l o c i t y due to a u x i l i a r y flow tends to oppose the downward moving annular s o l i d s , even though the a u x i l i a r y flows may induce a loosening or freer motion of the annular s o l i d s . The increase of the annulus gas flow diminishes with bed l e v e l . Hence for deeper beds, the loosening e f f e c t coupled with the sheer bulk weight of the annular s o l i d s may r e s u l t i n more p a r t i c l e s being entrained at the' spout-annulus i n t e r f a c e , thereby contributing to greater s o l i d s c i r c u l a t i o n . The e f f e c t s of a u x i l i a r y flow entry positions on the p a r t i c l e v e l o c i t y are shown i n Figures 7.3a and 7.3b. For configuration #2 (see 7.0 - 70 T CO 6.0 -E o 5.0 -CL > 4.0 -3.0 -2.0 -1.0 -H=60 cm H=45cm H=30cm 1.1 1.2 1.3 1.4 1.5 1.6 QT/Q T'^ms F i g . 7.1 Relationship between p a r t i c l e v e l o c i t y , V^, and Q^/Qms for d i f f e r e n t bed heights [ polystyrene, d^= 1.91 cm, q= 0 ] 70 tf> 6.0 £ ° 5.0 4.0 3.0 2.0 fr 1.0 -0 H=45cm! •t\— H = 30cm] 0 0.1 0.2 0.3 0.4 0.5 F i g . 7.2 Relationship between, p a r t i c l e v e l o c i t y , V , and the proportion of a u x i l i a r y flow r for d i f f e r e n t bed heights [ polystyrene, d^= 1.91 cm, 4.0 0 0.1 0.2 0.3 0.4 05" ' U F i g . . 7.3a R e l a t i o n s h i p between p a r t i c l e v e l o c i t y , V , and f r a c t i o n of - a u x i l i a r y flow w i t h c o n f i g u r a t i o n #2 [pol y s t y r e n e , P H= 60 cm, d.= 1.91 cml 9 • J F i g . 7.3b R e l a t i o n s h i p between p a r t i c l e v e l o c i t y , V , and f r a c t i o n of a u x i l i a r y flow w i t h c o n f i g u r a t i o n #3 [ p o l y s t y r e n e , P H=60 cm, d =1.91 cml i - 72 -Section 4.1), p a r t i c l e v e l o c i t y i n the annulus was found to increase with increasing a u x i l i a r y flow. However, with configuration #3, there was an i n i t i a l s l i g h t decrease of p a r t i c l e v e l o c i t y before i t increased with increasing a u x i l i a r y flow. A greater increase of p a r t i c l e v e l o c i t y i n the case of configuration #2 than configuration #3 was most l i k e l y due to more loosening of the annular s o l i d s . In configuration #3, a greater percentage of a u x i l i a r y flow bypassed d i r e c t l y into the spout. However, with increasing a u x i l i a r y flow, s o l i d s v e l o c i t y was observed to increase s u b s t a n t i a l l y beyond a c e r t a i n value of a u x i l i a r y flow. As noted by Yang (1983), there i s a minimum aeration required to s i g n i f i c a n t l y increase s o l i d c i r c u l a t i o n . From Figures 7.3a and 7.3b, these values, expressed as the r a t i o of a u x i l i a r y flow to t o t a l flow rate, were found to be approximately 0.25 and 0.30 respectively. For the case of HDPE (see figures 7.4), addition of a u x i l i a r y flow was found to decrease the s o l i d s c i r c u l a t i o n . For configuration #2, there was a s l i g h t increase of p a r t i c l e v e l o c i t y at higher a u x i l i a r y flow. For both configurations, the o v e r a l l s o l i d s c i r c u l a t i o n rate was less than that without any aeration. It may therefore be noted that the s o l i d s c i r c u l a t i o n rate for a given material and bed geometry i s affected by the following f a c t o r s : Factors promoting increased c i r c u l a t i o n : - higher gas flowrate i n the spout - loosening of annular s o l i d s due to a u x i l i a r y flow. - increased bed height Factor leading to reduced c i r c u l a t i o n : - higher gas flow i n the annulus. - 74 -CHAPTER 8 FOUNTAIN SHAPE AND HEIGHT AND SPOUT SHAPE AND DIAMETER 8.1 Measurement technique Fountain height was measured d i r e c t l y as the distance from the bed surface to the top of the fountain. Spout diameter was measured d i r e c t l y at an i n t e r v a l of 10 cm s t a r t i n g from the bed surface. 8.2 Results and Discussion 8.2.1 Fountain Shape and Height F i g . 8.1 shows that the height of the fountain increases with t o t a l gas flow, and that a shallower bed shows a greater fountain height for a given Q_/Q r a t i o , i- ms The e f f e c t of increasing the proportion of a u x i l i a r y flow on the height of the fountain i s shown i n F i g . 8.2. Fountain height decreases with increasing f r a c t i o n of a u x i l i a r y flow. This may be primarily due to r e d i s t r i b u t i o n of f l u i d between the spout and annulus - less f l u i d flows through the spout. Because of lower f l u i d flow through the spout, the p a r t i c l e v e l o c i t y i n the spout i s also reduced, r e s u l t i n g In a lower fountain height. (Grace and Mathur 1978). For a desired fountain height, a greater QT/Q r a t i o i s needed A ms for the case of spouting with aeration than for pure spouting. The shape of the fountains i s , however, quite d i f f e r e n t for the two cases. With aeration, the fountain shows l i t t l e tendency to overdevelop and i s - 75 -E Z 25 1-6 Q T / Q m f Fxg. 8.1 E f f e c t of Qj/Qrnf on H p for d i f f e r e n t values of bed heights [polystyrene, q= 0, d = 1.91 cm ] E u "a F i g . 8.2 Relationship between fountain height and the f r a c t i o n of a u x i l i a r y flow with c o n f i g u r a t i o n #1 f o r d i f f e r e n t bed heights [ polystyrene, Q T/Q m s= 1.4, d ±= 1.91 cm ] - 76 -usually well defined. I t was also observed to have a greater s o l i d s concentration. This preliminary observation proved to be of s i g n i f i c a n t importance since greater s o l i d s concentration could be achieved at the same fountain height, but at the expense of the extra flow required. The e f f e c t of a u x i l i a r y flow entry p o s i t i o n i s shown i n Figures 8.3a and 8.3b. There was no s i g n i f i c a n t difference i n the fountain shape and height. 8.2.2 Spout Shape and Diameter The spout assumed d i f f e r e n t shapes depending on the s o l i d properties. Spout shapes are shown i n F i g . 8.4. The spout diameter f o r m i l l e t p a r t i c l e s was nearly constant along i t s length ( F i g . 8.4a). For polystyrene p a r t i c l e s , the spout diameter was also observed to be nearly constant except near the bed surface where the spout showed some divergency ( F i g . 8.4b). For the case of HDPE p a r t i c l e s , a continuously divergent spout shape was observed ( F i g . 8.4c). A marked change of spout shape near the entrance region was noted at high a u x i l i a r y flow with configuration #3. The close proximity of the a u x i l i a r y flow entry p o s i t i o n to the spout-annulus Interface created a s i g n i f i c a n t l y " d i s t o r t e d " spout shape ( F i g . 8.4d). Predicted spout diameters due to McNab's empirical c o r r e l a t i o n are given i n Table 5. A comparison of the values shown i n Table 5 with the res u l t s of spout diameter (see Appendix VI) under various c e n t r a l and a u x i l i a r y flow combinations indicated that McNab's c o r r e l a t i o n predicted the data very well i f the sum of cen t r a l and a u x i l i a r y mass flows was taken as the mass flowrate. 35 r - 77--E 30 -o 0 I 1 ' L L_ J _ I i • • • 0 0.1 0.2 0.3 0.4 0.5 F i g . 8.3a E f f e c t o f ^ t h e f r a c t i o n of a u x i l i a r y flow w i t h c o n f i g u r a t i o n #2 on f o u n t a i n height,' H , [ p o l y s t y r e n e , H= 60 cm, d.= 1.91 cm'] 35 E 30 0 I 1 1 1 1 1 1 i i i i_ 0 0.1 0,2 0.3 0.4 0.5 F i g . 8.3b E f f e c t of the f r a c t i o n of a u x i l i a r y flow w i t h c o n f i g u r a t i o n //3 on f o u n t a i n h e i g h t , H , [ p o l y s t y r e n e , H= 60 cm, d.= 1.91 cm ] F i g . 8.4 Sketches showing spout shapes f o r various s o l i d m a t e r i a l s i n v e s t i g a t e d . - 79 -Table 5: Predicted Values of Average Spout Diameter Using McNab's Empirical C o r r e l a t i o n [Polystyrene p a r t i c l e s ] . Q d s Q d s 3.5 2.60 7.0 3.66 4.0 2.78 7.5 3.78 4.5 2.94 8.0 3.90 5.0 3.10 8.5 4.02 5.5 3.25 9.0 4.14 6.0 3.39 9.5 4.25 6.5 3.53 10.0 4.35 - 80 -CHAPTER 9 CONCLUSIONS AND SUGGESTIONS FOR FURTHER WORK 9.1 Conclusions At various ce n t r a l flow and a u x i l i a r y flow combinations, four d i f f e r e n t flow regimes of behaviour were established: Packed bed; spouting with aeration; s p o u t - f l u i d i z a t i o n and submerged j e t i n a f l u i d i z e d bed. These flow regimes shared many s i m i l a r i t i e s to previously determined regime maps. For the case of s p o u t - f l u i d i z a t i o n , spout i n s t a b i l i t y i s developed as a res u l t of bubble formation i n the spout near the bed surface. The minimum t o t a l f l u i d flowrate f o r spouting with aeration and s p o u t - f l u i d i z a t i o n i s always found to be greater than the minimum spouting flowrate. An improved c o r r e l a t i o n for p r e d i c t i n g minimum f l u i d flowrate for spouting with aeration i s proposed. Greater f l u i d p e rcolation through the annulus, e s p e c i a l l y i n the lower section, could be achieved by increasing the amount of a u x i l i a r y flow. An increase of as much as 50% over the corresponding pure spouting case could be r e a l i z e d near the c o n i c a l - c y l i n d r i c a l junction for a 1:1 s p l i t between cent r a l and a u x i l i a r y flow. Annulus gas v e l o c i t y data were i n good agreement with an equation due to Littman (1976) i f Umf i s replaced by ^AHm a n c* it \ i s f * s t r e a t e d as an adjustable parameter. Solids c i r c u l a t i o n rate was found to be l i t t l e affected by small rates of aeration. At higher rates of aeration and deeper bed heights, an increase of s o l i d s c i r c u l a t i o n was obtained. However, at lower bed height, the s o l i d s c i r c u l a t i o n rate was found to decrease. - 81 -The overall bed pressure drop for spouting with aeration under minimum conditions increases linearly with increasing auxiliary flow. Fountain height was found to decrease with increasing fraction of auxiliary flow. For spouting with aeration, solids in the fountain were observed to have a greater concentration than pure spouting at a given fountain height. The empirical correlation due to McNab was found to predict the average spout diameter very well under various central and auxiliary flow combinations i f the sum of central and auxiliary flows is used in the correlation. 9.2 Recommendations For Fu r t h e r Work Further solid materials suitable for spout-fluid beds that w i l l extend the regime of spouting with aeration should be investigated. A correlation for K, together with factors that affect the values T^USci m^Sci for H , (——) and (——) . , should be sought, msf Q . max Q ,, min mt ml The regime of spout-fluidization with respect to gas distribution, frequency and causes of bubble formation, solids circulation and pressure drop should receive further attention. - 82 -NOTATION A^ - Cross-sectional area of the annulus (cm ) 2 A c - Cross-sectional area of the column (cm ) D - Column diameter (cm) c ' 2 G - Gas mass flowrate (g/cm s) H - Bed height (cm) Hp - Fountain height (cm) H M - Maximum spoutable bed height (cm) Hmsf ~ ^ a x ^ m u m height f or spo u t - f l u i d i z e d bed (cm) K - Empirical constant Q - Central spouting flow (1/s) - Minimum spouting flowrate (1/s) Q m£ - Minimum f l u i d i z a t i o n flowrate (1/s) Q m g a - Central spouting flow under the condition of minimum spouting with aeration (1/s) Q T , m g a - Sum of central spouting flow and a u x i l i a r y flow under the condition of minimum spouting with aeration, = Qmsa + qmsa (1/s) Q T - Sum of central spouting flow and a u x i l i a r y flow (1/s) Sr - So l i d c i r c u l a t i o n rate (g/s) U - gas s u p e r f i c i a l v e l o c i t y (cm/s) U ^ ( Z ) - Annulus gas v e l o c i t y at bed l e v e l Z (cm/s) U"AH - Annulus gas v e l o c i t y at Z = H (cm/s) U . - Annulus gas v e l o c i t y at H = H (cm/s) - 83 -U j. - Minimum f l u i d i z a t i o n v e l o c i t y (cm/s) mf U"ms - Minimum spouting v e l o c i t y (cm/s) Ug H - Gas s u p e r f i c i a l v e l o c i t y i n the spout at Z = H (cm/s) ^T'msf ~ Minimum f l u i d s u p e r f i c i a l v e l o c i t y f o r s p o u t - f l u i d i z a t i o n (cm/s) ^T'msa ~ M * n i m u m f l u i d s u p e r f i c i a l v e l o c i t y f o r spouting with aeration (cm/s) Vp - p a r t i c l e v e l o c i t y i n the annulus (cm/s) Z - Height coordinate, Z = 0 at base (cm) d^ - diameter of i n l e t o r i f i c e (cm) dp - P a r t i c l e diameter, equi-volume sphere diameter (cm) d - Spout diameter (cm) s g - Acceleration of gravity (cm/s ) h = H/H, m h f H/H , msf msf h . = 1 - ( 1 - h . ) 3 msf msf q - A u x i l i a r y flow (1/s) q m g a - A u x i l i a r y flow under the conditions of minimum spouting with aeration (1/s) q - A u x i l i a r y flow through a l l f i v e subdistributor chambers (1/s) q u - A u x i l i a r y flow through upper two subdistributors only (1/s) q^ - A u x i l i a r y flow through lower two subdistributors only (1/s) - 84 -r . = q„/Q. a r l AP AH AP s 5> AH AP AH P ?b p s v. a / y T " 1 l / Q T = f(U), pressure drop per unit bed height AP f - Pressure drop of the f l u i d i z e d bed (cm H 20) AP - Pressure drop of the bed at minimum f l u i d i z a t i o n m f conditions < c m H 2 ° ) = Over a l l pressure drop of the s p o u t - f l u i d bed (cm H2O) - Pressure drop of the spout-fluid bed per unit bed height — - Pressure drop of the f l u i d i z e d bed per unit bed height (i E . ) - D i f f e r e n t i a l bed pressure drop dZ e. - Voidage :in the annulus e Q - Spout voidage at bed surface l e v e l o max 3 F l u i d density (g/cm ) Solids bulk density (g/cm3) 3 Density of s o l i d p a r t i c l e (g/cm ) P a r t i c l e v e l o c i t y along axis of column at bed surface (cm/s) Empirical constant, 0 = 0.20 d - ° ' 3 2 0 d ° ' 2 3 5 H 0 - 1 6 0 P 1 - 85 -REFERENCES C. Dumistrescu, "The Hydrodynamical Aspects of a Spouted Bed Modified by the Introduction of an Add i t i o n a l Flow", Revista de Chimie 28(8), Roumania (1977). 746-754. J . Eastwood, E.J.P. Matzen, M.J. Young and N. Epstein, B r i t . Chem. Eng., _14, 1542 (1967). Y E l j a s , "Contribution to the Study of Spouted Beds with P a r t i c u l a r Emphasis on Porosity", Paper No. 58d, 68th Annual AIChE Meeting, Los Angeles, November 1975. Epstein, N., C.J. Lim and K.B. Mathur, "Data and Models for Flow D i s t r i b u t i o n and Pressure Drop i n Spouted Beds", Can. J . Chem Eng., 56, 436 (1978). J.R. Grace and K.B. Mathur, "Height and Structure of the Fountain Region Above Spouted Beds", Can. J . Chem. Eng. 56_, 533 (1978). Z.B. Grbavcic, D.V. Vukovic, F.K. Zdanski, and H. Littman, " F l u i d Flow Pattern, Minimum Spouting V e l o c i t y and Pressure Drop i n Spouted Beds", Can. J . Chem. Eng. 54, 33-42 (1976). Dz. E. Hadzismajlovic, Z.B. Grbavcic, D.V. Vukovic and H. Littman, "The Mechanics of Spout-Fluid Beds at the Minimum Spout-Fluid Flowrate", Can. J . Chem. Eng. 61^ , 343 (1983). C. H e l l and M. Tels "Pressure D i s t r i b u t i o n i n Spout-fluid Bed Reactors", Can. J. Chem. Eng. 61_, 331 (1983). C.J. Lim, "Gas Residence Time D i s t r i b u t i o n and Related Flow Patterns i n Spouted Beds", Ph.D D i s s e r t a t i o n . The Univ e r s i t y of B r i t i s h Columbia, Vancouver (1975). H. Littman, D.V. Vukovic, F.K. Zdanski, and Z.B. Grbavcic, "Pressure Drop and Flowrate C h a r a c t e r i s t i c s of a Liqu i d Phase Spout-Fluid Bed at the Minimum Spout-Fluid Flowrate", Can. J. Chem. Eng. 52, 174-79 (1974). H. Littman, D.V. Vukovic, F.K. Zdanski and Z.B. Grbavcic, "Basic Relations f o r the Liquid Phase Spout-Fluid Flowrate", F l u i d i z a t i o n Technology (Keairns. D.L. ed) 1, Hemisphere (1976), 373-386. H. Kono, "A New Concept For Three Phase F l u i d i z e d Beds", Hydrocarbon Processing, 123-129, Jan. 1980. H. Kono, "Granulation of Small Granules from Fine Powder i n Spouted F l u i d i z e d Bed Granulators", Int. Symp. on Powder Technology. '81. Sept 27 - Oct. 1. 1981, Kyoto, Japan. T. Mamuro and H. H a t t o r i , " Flow Pattern of F l u i d i n Spouted Beds", J. Chem. Eng. Jap., 1, 1 (1968) / corre c t i o n , J . Chem. Eng. Jap., 3, 119 (1970). - 86 -Mathur, K.B., Gishler, P.E., "A Technique for Contacting Gases with Coarse S o l i d P a r t i c l e s " , A.I. Ch. E.J. 1, 157 (1955). K.B. Mathur and N^ Epstein, "Development i n Spouted Bed Technology", Can. J. Chem. Eng., 52, 129 (1974). K.B. Mathur and N. Epstein, Spouted Beds, Academic Press, New York (1974). Lim, C.J. and Mathur, K.B. "Residence Time D i s t r i b u t i o n of Gas i n Spouted Beds", Can. J . Chem. Eng. 52, 150-155 (1974). McNab, G.S. "Prediction of Spout Diameter", B r i t . Chem. Eng. & Proc. tech. 1_7, 532 (1972). M i k h a i l i k , V.D., Collected works on "Research on Heat and Mass Transfer i n Technological Processes", p. 37, Naukai Tekhnika BSSR, Minsk, 1966. Nagarkatti, A., Chatterjee, A., "Pressure and Flow C h a r a c t e r i s t i c s of a Gas Phase Spout-Fluid Bed and the Minimum Spout-Fluid Condition", Can. J . Chem. Eng. 52, 185 (1974). A.O. Oman and K.M. Watson, Refinery Management and Petroleum Chem. Tech., 36, R-795 (1944). P.N. Rowe, Movie session presentation at International F l u i d i z a t i o n Conference, Kachikojima, Japan. June, 1983. D.V. Vukovic., Dz. E. Hadzismajcovic., Z.B. Grbavcic., R.V. Garic and H. Littman, "Regime Maps For Two-Phase F l u i d - S o l i d s Mobile Beds i n a V e r t i c a l Column with Nozzle and Annular Flow", paper presented at the 2nd Int. Symp. On Spouted Beds Vancouver, B.C. Canada (Oct. 4, 1982). D.V. Vukovic, F.K. Zdanski, and Z.B. Grbavcic, "Ef f e c t of Annular and Nozzle Flow of F l u i d on the Behaviour of a Spouted F l u i d i z e d Bed", 4th Int. CHISA '72 Congress, Prague, Czechoslovakia, Sept. 11-15, 1972, Filmotheka, Paper C3.8. W.C. Yang and D.L. Keairns, "Studies on the S o l i d C i r c u l a t i o n Rate and Gas Bypassing i n a Spouted Fluid-Bed with a Draft Tube", Can. J. Chem. Eng. 6J_, 349 (1983). - 87 -A P P E N D I C E S Appendix I Pressure Drop-gas V e l o c i t y Equations for Loosely-packed Beds of the Solids M a t e r i a l Investigated. M a t e r i a l a 0 a i a 2 33 ai+ a5 Polystyrene HDPE M i l l e t -71.1197 191.6519 44.6259 191.7383 -361.1952 - 18.0998 -153.3241 300.2185 - 5.5045 61.5574 -114.0607 7.3752 -11.7256 20.6864 - 1.7256 0.8557 -1.4434 0.1230 i M a t e r i a l s b 0 b l b 2 b 3 b 4 b.5 Polystyrene HDPE M i l l e t 24.1395 2.3423 E - l -17.1777 -3.4035 8.518 E-3 1.8143 1.8885 E - l 7.2766 E-4 -4.9902 E-2 -4.9307 E-3 3.0771 E-6 3.8694 E-6 6.2246 E-5 -4.4759 E-8 1.9004 E-5 -3.0515 E-7 -8.5587 E - l l -1.9886 E-7 U A (cm/s) = a0. + a i AH + a2 AH 2 + a 3 AH3 + a^ AH** + a 5 AH 5 AH (cm) = bo + b i U A + b2 U A 2 + b 3 U~A3 + bh + b 5 U A & Where AH i s the value of the d i f f e r e n t i a l l i n e a r movement of the manometer f l u i d i n cm of a 15° i n c l i n e d manometer f i l l e d with l i q u i d of s p e c i f i c gravity 0.827. The value of AH corresponds to 2 cm of bed l e v e l . APPENDIX I I _ SOLIDS-FREE PRESSURE DROP-CENTRAL FLOW CORRECTION CUPVE O E-10 i * 1 1 1 I I 1 , 1 2 3 4 5 6 7 8 9 10 CENTRAL AIR FLOW ( l/s ) - .90 -APPENDIX III CALIBRATION CURVES FOR ORIFICE PLATE FLOWMETERS - 91 -12.0 F i g . I I I . l C a l i b r a t i o n curve for o r i f i c e flowmeter f o r the c e n t r a l a i r f l o w l i n e 3.5 </> 3.0 - 2.5 *-» a | 2.0 LL 1.5 1.0 as -i 1 r ~i 1 r r Conditions for c a l i b r a t i o n : a i r temperature = 20 °C i n l e t upstream a i r pressure = 40 kPa -T 1 1 1 1 r -i i_ -J ' • 0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 A P 1 / 2 , ( c m H 2 0 ) V 2 F i g . III.2 C a l i b r a t i o n curve for o r i f i c e flowmeter for each a u x i l i a r y flow l i n e 93 -A i r flowrate correction to account for d i f f e r e n t a i r temperature and i n l e t upstream pressure: ( i ) C orrection f a c t o r , f, for o r i f i c e flowmeter for the c e n t r a l a i r flow l i n e . -,1/2 f = 0.6164 T„ +273 N  P.. + 101.325 N ( i i ) Correction f a c t o r , f, for o r i f i c e flowmeter for each of the a u x i l i a r y a i r flow li n e s -.1/2 f = 0.6945 T„ +273 N P„ +101.325 Where - a i r temperature (°C) Pjj - i n l e t upstream pressure (kPa) APPENDIX IV --94 -DIMENSIONS FOR ORIFICE PLATE FLOWMETERS T a JL b T ( Dimensions for ori f ice f l owme te r s ' , ( mm. ) a b C d Central a i r -flow l ine 2 5. A 12.7 25.4 12.7 Aux i l i a ry air flow l ines 12.7 6.35 1 2.7 6.35 M a t e r i a l of c o n s t r u c t i o n : brass - 95 -APPENDIX V EXPERIMENTAL CONDITIONS DESIGNATION The run number i s expressed i n the form of Run N1-N2-N3 Where the values of N's are as follow: Nl - Refers to the combination of bed m a t e r i a l , bed height and i n l e t o r i f i c e plate diameter (see Table V . l ) . N2 - Refers to the dependent v a r i a b l e that i s being determined, (see Tabe V.2). N3 - Refers to a u x i l i a r y flow configuration (see Table V.3). - 96 -Table V.1 Values of NI for D i f f e r e n t Combination of Bed M a t e r i a l , Bed Height and I n l e t O r i f i c e Plate Diameter. NI Materials H (cm) d i (cm) 1 Polystyrene 30 1.91 2 Polystyrene 45 1.91 3 Polystyrene 60 1.91 4 HDPE 30 1.91 5 HDPE 35 1.91 6 M i l l e t 30 1.91 7 M i l l e t 45 1.91 8 Polystyrene 45 2.54 9 Polystyrene 60 2.54 10 M i l l e t 30 2.54 - 97 -Table V.2 Values of N2 for D i f f e r e n t Dependent Variables Investigated. N2 Dependent Variables 1 Regime map 2 Gas V e l o c i t y i n the annulus 3 O v e r a l l bed pressure drop 4 P a r t i c l e v e l o c i t y 5 Fountain height 6 Spout diameter Table V.3 Values of N3 for D i f f e r e n t A u x i l i a r y Flow Configuration (see Section 4.1) N3 A u x i l i a r y Flow Configurations 1 #1 2 #2 3 #3 - 98 -APPENDIX VI EXPERIMENTAL DATA RUN# 3-2-1 Q 8 6 5 4 q a 0 2 3 4 Z UA UA UA UA 58 53.67 54.24 56.10 57.09 48 51.21 52.22 53.95 55.53 38 47.09 49.89 51.93 54.53 28 41.18 45.14 48.42 51.64 23 35.84 41.18 45.44 49.75 18 29.29 39.51 43.02 48.13 RUN# 9-2-1 Q 8.5 6.5 5.5 4.5 q a 0.0 2.0 3.0 4.0 Z UA UA UA UA - 58 56.85 57.90 58.15 58.80 48 55.35 56.24 56.53 58.35 38 52.16 54.24 55.39 56.96 28 47.23 50.77 53.24 55.53 23 42.71 48.27 51.93 54.96 18 38.96 46.19 49.80 54.39 15 34.88 44.53 48.27 53.81 - 99 RUN# 2-2-1 7.5 5.5 4.5 z UA UA UA 43 48.85 52.00 54.16 38 46.07 50.45 52.59 33 44.15 48.23 50.96 28 40.76 46.15 49.16 23 35.70 41.95 46.43 18 28.38 39.65 43.75 RUN# 5-2-1 Q 10.5 8.5 q a 0 2 Z UA UA 33 62.65 64.39 28 59.98 63.52 23 55.40 60.58 18 50.61 56.95 15 45.91 53.82 - 100 -RUN# 9-2-2 Q 8.5 6.5 5.5 0 2 3 z UA UA UA 58 56.85 58.80 59.00 48 55.35 56.81 57.94 38 52.16 54.81 57.09 28 47.23 51.93 55.80 23 42.71 49.89 53.95 18 38.96 47.83 53.09 15 34.88 46.34 51.93 RUN# 9-2-3 Q 8.5 6.5 5.5 % 0.0 2.0 3.0 1 UA UA UA 58 56.85 57.00 57.66 48 55.35 53.39 55.50 38 52.16 53.09 55.25 28 47.23 49.30 52.51 23 42.71 46.00 50.48 18 38.96 43.02 47.23 15 34.88 39.94 42.41 - 101 -RUN# 1-3-1 RUN# 1-3-2 RUN# 1-3-3 q a q u q1 A P s 0 5.7 2 7.8 2 8.3 2 7.7 3 9.1 3 9.1 3 8.2 RUN# 3-3-1 RUN# 3-3-2 RUN# 3-3-3 % A p 3 q u A P s q1 AP s 0 15.4 2 19.1 2 18.8 2 19.4 3 20.8 3 20.8 3 20.6 4 21.9 4 22.8 4 22.7 RUN# 2-3-1 RUN# 8-3-1 q a a P s 0 9.6 2 13.2 3 14.6 4 17.0 q a * P s 0 18.25 2 19.40 3 19.50 RUN# 9-3-1 q AP ^a s 0 23.65 2 25.85 3 26.37 - 102 -RUN# 4-4-2 Q 8.5 4.22 3.94 4.29 4.17 0 9.5 4.76 4.98 4.90 4.85 10.5 5.59 5.38 5.55 5.65 8.0 3.73 3.48 3.51 3.72 1 9.0 4.29 4.55 4.18 4.31 10.0 4.98 5.03 5.00 4.93 7.0 3.95 3.98 4.02 3.98 2 8.0 4.41 4.46 4.57 4.22 9.0 5.10 4.67 4.83 5.00 RUN# 4-4-3 • Q V P 8 3.60 3.68 3.75 3.66 1 9 4.20 4.44 4.61 4.42 10 4.93 5.29 4.93 5.15 2 7 8 9 10 3.38 3.94 4.55 5.15 3.15 3.82 4.57 5.18 3.26 3.91 4.63 5.03 3.24 3.89 4.57 5.24 - 103 -RUN# 3-4-2 % Q V P 6.0 4.29 4.27 4.31 4.31 2 7.0 5.00 4.95 5.10 4.90 8.0 5.71 5.38 5.38 5.71 5.0 4.55 4.55 4.63 4.41 3 6.0 5.18 5.24 5.13 5.29 7.0 5.56 5.85 5.85 5.92 4.5 5.41 5.62 5.43 5.58 4 5.0 5.85 5.56 5.81 5.81 6.0 6.17 6.21 6.29 6.21 RUN# 3-4-3 q l Q V P 6.0 4.07 4.00 4.08 4.01 2 7.0 4.67 4.72 4.59 4.72 8.0 5.29 5.38 5.49 5.35 5.0 4.27 4.15 4.10 4.26 3 6.0 4.78 4.81 4.83 4.78 7.0 5.32 5.32 5.62 5.56 4.5 5.35 5.26 5.29 5.13 4 5.0 5.62 5.29 5.59 5.52 6.0 5.75 5.75 6.06 5.78 - 104 -RUN# 3-4-1 q a Q V P 7 3.48 3.75 3.50 3.47 0 8 4.00 4.29 4.39 4.18 9 4.78 4.88 4.81 4.88 5.5 3.89 3.95 3.79 3.85 2 6.5 4.67 4.52 4.72 4.67 7.5 5.41 5.21 5.10 5.21 4.5 4.27 4.39 4.35 4.41 3 5.5 5.08 4.85 4.88 4.85 6.5 5.65 5.59 5.71 5.55 4.0 5.13 4.95 5.15 4.90 4 4.5 5.43 5.26 5.18 5.35 5.5 5.88 5.99 5.88 5.81 - 105 -RUN# 2-4-1 Q V p 7 2.74 2.68 2.63 2.63 0 8 3.12 3.08 3.10 3.11 9 3.64 3.68 3.39 3.47 5.5 2.86 2.97 2.89 2.90 2 6.5 3.55 3.39 3.30 3.37 7.5 3.62 3.84 3.78 3.95 4.5 3.12 3.08 3.11 3.09 3 5.5 3.58 3.61 3.57 3.64 6.5 3.94 3.92 4.03 4.13 3.5 3.62 3.40 3.39 3.57 4 4.5 4.00 4.10 3.83 4.12 5.5 4.44 4.42 4.37 4.29 RUN# 2-4-2 % Q V P • 4.5 3.05 3.14 3.07 3.00 3 . 5.5 3.68 3.55 3.64 3.70 6.5 4.03 4.05 4.33 4.24 RUN* 2-4-3 q l Q 4.5 2.77 2.86 2.73 2.90 3 5.5 3.38 3.30 3.38 3.36 6.5 3.79 3.72 2.76 3.69 - 106 -RUN# 1-4-1 Q V p 0 6 7 8 1.45 1.83 2.15 1.43 1.86 2.26 1.43 :-. 1.78 2.20 1.45 1.83 2.16 2 4.5 5.5 6.5 1.44 1.98 2.39 1.49 1.92 2.32 1.45 1.94 2.37 1.43 1.88 2.33 3 3.5 4.5 5.5 1.47 1.85 2.35 1.48 1.99 2.42 1.41 1.94 2.44 1.39 1.91 2,38 3.5 3.0 4.0 1.34 1.87 1.32 1.83 1.30 1.81 1.36 1.79 RUN# 1 -4-2 % Q V 2 4.5 5.0 6.0 1.50 1.73 2.24 1.40 1.75 2.22 1.45 1.74 2.35 1.41 1.75 2.25 RUN# 1-4-3 q1 Q 4 1.45 1.43 1.43 1.45 2 5 1.83 1.86 1.78 1.83 6 2.15 2.26 2.20 2.16 - 107 -RUN# 1-5-2 % Q H F 4.5 8.5 8.5 2 5.0 13.5' 13.0 6.0 23.0 22.5 3 3.5 4.5 5.5 6.0 15.0 24.0 5.0 14.5 24.0 RUN# 1-5-3 - q l Q H F 4.5 9.5 9.0 2 5.0 14.0 13.5 6.0 23.0 23.0 3.5 6.5 7.0 3 4.5 16.0 15.5 5.5 25.5 25.0 - 108 -RUN# 2-5-1 q a Q H 0 6.5 7.0 7.5 8.0 8.5 9.0 5.0 9.0 14.0 19.0 22.5 28.0 4.5 9.5 14.0 18.5 23.5 28.5 2 5.5 6.5 7.5 9.0 17.0 27.0 9.0 17.5 26.5 3 4.5 5.5 6.5 7.0 16.5 26.0 7.5 17.0 25.5 4 3.5 4.5 5.5 6.0 14.5 24.0 6.0 15.0 24.0 RUN# 2-5-2 q u Q H F 3 4.5 5.5 6.5 7.0 16.0 25.0 7.0 15.0 24.0 RUN# 2-5-3 q l Q H F 3 • 4.5 5.5 6.5 7.5 17.0 26.5 7.0 16.0 26.0 - 109 -RUN# 3-5-2 % Q H F 6.0 8.5 8.5 2 7.0 16.0 16.5 8.0 25.0 25.5 5.0 6.0 6.0 3 . 6.0 15.0 15.0 7.0 24.0 24.5 4.5 8.5 8.5 4 5.0 13.0 13.5 6.0 22.5 22.5 RUN# 3-5-3 q l Q H F 6.0 8.0 8.0 2 7.0 16.5 16.5 8.0 26.5 27.0 5.0 6.0 6.0 3 6.0 15.0 15.0 7.0 25.0 25.5 4.5 8.5 8.5 4 5.0 13.5 13.5 6.0 23.5 24.0 110 -RUN# 1-5-1 Q H 5.5 7.5 7.5 6.0 12.5 12.0 6.5 17.0 16.5 0 7.0 22.5 21.5 7.5 27.0 26.5 8.0 30.0 30.0 4.5 8.5 9.0 2 5.5 18.0 18.0 6.5 27.0 26.5 3.5 7.0 6.5 3 4.5 16.0 15.5 5.5 25.0 25.0 3.0 5.0 5.0 3.5 4.0 14.0 14.5 4.5 18.5 19.0 RUN# 3-5-1 % Q H 7.0 3.0 3.0 0 8.0 10.0 10.0 9.0 19.5 19.0 5.5 5,0 5.0 2 6.5 14.5 15.0 7.5 20.0 20.5 4.0 6.5 6.5 4 4.5 9.0 9.0 5.5 19.0 19.5 RUN// 1 -6 -1 - I l l -30 20 10 Q % d s 6 .0 3 . 5 0 3 . 50 3 . 50 7 . 0 0 3 .75 3 .75 3 . 75 8 . 0 4 . 0 0 4 . 0 0 3 . 75 4 . 5 3 . 50 3 .25 3 . 00 5.5 2 3 .75 3 . 5 0 3 . 50 6 .5 4 . 0 0 4 . 0 0 3 . 50 3.5 3 .00 3 . 00 2 .75 4 . 5 3 3.75 3 . 50 3 .25 5 .5 4 . 0 0 4 . 0 0 3 . 50 RUN// 1-6--2 Z 30 20 10 Q qu d s 4 . 5 3 .25 3 . 25 3 . 0 0 5 .0 2 3 .50 3 . 25 3 . 00 6 .0 4 . 0 0 3 . 75 3 . 25 3 .5 3 . 00 3 . 0 0 2 .75 4 . 5 3 3 .50 3 .25 3 . 0 0 5.5 4 . 0 0 3 .75 3 . 50 RUN// 1-6-3 z 30 20 10 Q q l d L_ S 4 . 5 3 . 00 3 . 00 3 . 00 5 . 0 2 3 .50 3 . 50 3 . 25 6 . 0 4 . 0 0 4 . 0 0 3 . 50 3 . 5 3 . 25 3 . 25 3 . 0 0 4 . 5 3 3 .75 3 . 50 3 . 50 5.5 4 . 0 0 4 . 0 0 3 .75 - 112 -RUN// 2-6-1 z 45 35 25 15 Q q a d s 7.0 4.00 3.75 3.50 3.50 8.0 0 4.00 4.00 3.75 3.75 9.0 4.25 4.25 4.25 4.25 5.5 4.00 3.75 3.50 3.50 6.5 2 4.25 4.00 4.00 3.75 7.5 4.50 4.25 4.00 4.00 4.5 4.00 3.75 3.75 3.50 5.5 3 4.00 4.00 4.00 3.75 6.5 4.50 4.50 4.25 4.00 3.5 4.25 4.00 3.50 3.50 4.5 4 4.00 4.00 3.75 3.50 5.5 4.25 4.25 4.00 4.00 RUN// 2-6-2 z 45 35 25 15 Q Si d s 4.5 4.00 3.75 3.50 3.25 5.5 3 4.00 4.00 3.75 3.50 6.5 4.50 4.25 4.00 3.75 RUN// 2-6-3 z 45 35 25 15 Q q l d s 4.5 5.5 6.5 3 4.25 4.25 4.50 4.00 •• 4.00 4.25 3.75 4.00 4.00 3.50 3.75 4.00 - 113 -RUN// 3 - 6 - 2 z 60 50 40 30 20 Q q u d s 6 .0 4 . 5 0 4 . 2 5 4 . 0 0 3 .75 3 . 75 7 . 0 2 4 . 5 0 4 . 2 5 4 . 0 0 4 . 0 0 4 . 0 0 8 . 0 4 . 5 0 4 . 5 0 4 . 25 4 . 2 5 4 . 2 5 5 .0 4 . 5 0 4 . 25 4 . 0 0 3 .75 3 . 5 0 6 .0 3 4 . 25 4 . 25 4 . 0 0 4 . 0 0 4 . 0 0 7 . 0 4 . 5 0 4 . 5 0 4 . 5 0 4 . 25 4 . 2 5 4 . 5 4 . 75 4 . 5 0 4 . 0 0 3 . 75 3 . 5 0 5 .0 4 4 . 5 0 4 . 5 0 4 . 0 0 4 . 0 0 3 . 75 6 .0 4 . 75 4 . 7 5 4 . 2 5 4 . 0 0 4 . 0 0 RUN// 3 - 6 - 3 z 60 50 40 30 20 Q q l d s 6 .0 4 . 2 5 4 . 25 4 . 0 0 3 .75 3 . 75 7 .0 2 4 . 25 4 . 0 0 4 . 0 0 4 . 0 0 4 . 0 0 8 . 0 4 . 5 0 4 . 5 0 4 . 25 4 . 2 5 4 . 2 5 5.0 4 . 2 5 4 . 0 0 3 . 75 3 . 75 3 . 75 6 .0 3 4 . 2 5 4 . 2 5 4 . 0 0 4 . 0 0 4 . 0 0 7 . 0 4 . 5 0 4 . 5 0 4 . 7 5 4 . 25 4 . 2 5 4 . 5 4 . 5 0 4 . 2 5 4 . 0 0 3 . 75 3 . 75 5.0 4 4 . 5 0 4 . 5 0 4 . 2 5 4 . 0 0 4 . 0 0 6 . 0 " 4 . 75 4 . 5 0 4 . 5 0 4 . 25 4 . 0 0 114 -RUN// 3-6-1 60 50 AO 30 20 Q q a d. s 7.0 4.00 4.00 3.75 3.50 3.50 8.0 0 4.00 4.00 4.00 4.00 4.00 9.0 4.50 4.50 4.25 4.25 4.25 5.5 4.50 4.00 3.75 3.75 3.50 6.5 2 4.25 4.25 4.00 4.00 4.00 7.5 4.50 4.50 4.25 4.25 4.25 A - 5 4.25 4.00 3.75 3.50 3.50 5.5 3 4.25 4.25 4.00 3.75 - 3.75 < 6.5 4.50 4.50 4.25 4.25 4.25 4.0 4.50 4.25 4.00 3.75 3.50 4.5 • 4 4.50 4.25 4.00 3.25 3.75 5.5 4.50 4.25 4.00 4.00 4.00 

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