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New pilot plant technique for designing gas absorbers with chemical reactions Tontiwachwuthikul, Paitoon 1990

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NEW PILOT P L A N T TECHNIQUE FOR DESIGNING G A S A B S O R B E R S WITH C H E M I C A L R E A C T I O N S by PAITOON TONTIWACHWUTHIKUL B.Eng.(Hons.), King Mongkut's Institute of Technology, Thailand, 1983 B.A.(Political Science), Ramkhamhaeng University, Thailand, 1983 M.Eng.(Chemical Engineering), The University of British Columbia, 1986  A T H E S I S S U B M I T T E D IN P A R T I A L F U L F I L M E N T O F T H E REQUIREMENTS FOR T H E DEGREE OF DOCTOR OF PHILOSOPHY in T H E F A C U L T Y O F G R A D U A T E STUDIES DEPARTMENT OF CHEMICAL ENGINEERING  We accept this thesis as conforming to the required standard  T H E U N I V E R S I T Y O F BRITISH C O L U M B I A December  1990  (c) Paitoon Tontiwachwuthikul,  1990  In presenting this thesis in partial fulfilment of the requirements for an advanced degree at The University of British Columbia, I agree that the Library shall make it freely available for reference and study. I further agree that permission for extensive copying of this thesis for scholarly purposes may be granted by the Head of my Department or by his or her representatives. It is understood that copying or publication of this thesis for financial gain shall not be allowed without my written permission.  Department of Chemical Engineering The University of British Columbia 2075 Wesbrook Mall Vancouver, B . C . , Canada V 6 T 1Z3 Date: December 1990  i i ABSTRACT  Gas  absorption  unit operation the  with chemical reaction  i n the chemical  s e l e c t i v e removal  streams.  Apart  difficult  problems  and petroleum i n d u s t r i e s f o r  components  from c h o o s i n g  and p e r f o r m a n c e the  of  from i n d u s t r i a l  a b s o r p t i o n media,  gas  t h e most  facing the design engineer a r e the s i z i n g  p r e d i c t i o n of  s c a r c i t y of  i s an i m p o r t a n t  t h e a b s o r p t i o n tower  fundamental design  due t o  data, especially  when  n o v e l a b s o r p t i o n media and/or p a c k i n g s a r e used.  The of  s o l u b i l i t y of carbon d i o x i d e  2-amino-2-methyl-1-propanol  i n 2 and 3 M s o l u t i o n s  (AMP),  which  is a  newly  i n t r o d u c e d a b s o r b e n t , was d e t e r m i n e d a t 2 0 , 4 0 , 60 a n d 80 ° C f o r C O 2 p a r t i a l pressures ranging  and to  100 k P a .  The r e s u l t s  Kent-Eisenberg previous  c a p a c i t i e s o f AMP a n d also  were i n t e r p r e t e d w i t h  model . w h i c h  experimental  from a p p r o x i m a t e l y 1  predicted  results  the  well.  monoethanolamine  The  a modified present  and  absorption  (MEA) s o l u t i o n s  were  compared.  Detailed  concentration  and  were r e p o r t e d f o r t h e a b s o r p t i o n i n t o NaOH,  MEA a n d AMP  (0.1 m I D , p a c k e d w i t h  temperature  measurements  o f carbon d i o x i d e from a i r  solutions.  A  f u l l - l e n g t h absorber  12.7 mm B e r l S a d d l e s up t o h e i g h t s o f  6.55 m) was u s e d . I t was o p e r a t e d i n c o u n t e r c u r r e n t mode a n d a t 30 t o 75 % f l o o d i n g  v e l o c i t i e s which a r e t y p i c a l  f o r gas  absorber  operations.  The  following  ranges of  c o n d i t i o n s were e m p l o y e d : s u p e r f i c i a l gas 14.8  mol/m  m^/m  s;  superficial  feed C O 2  h;  2  2  absorbent  14 t o  measurements compared  20  for  with  1.2  to  °C;  the  11.5 3.8  CC^-MEA  -  a  superior  c a p a c i t i e s and  A  new  (PPT),  for  has  found  to  procedure,  It  features  of  parameters interfacial  the  feed  systems  were  developed  was  obtained  Compared  with  CO2  absorption  i s b a s e d on  a  be  with  is  Plant  Technique  chemical  the premise  small-scale pilot PPT  are  and  ( i ) the transfer  liquid  i n f o r m a t i o n of the  reaction  rate constants) avoided.  reactions  p r i m a r i l y intended  s i z e d by m a k i n g  chemical  c a l c u l a t i o n s are  PPT  Pilot  f o r which fundamental design  ( i . e . mass area  absorbers  The  a b s o r p t i o n columns can t e s t s using  c a l l e d the  gas  been d e v e l o p e d .  designing absorbers  of  total  i n f e r i o r mass t r a n s f e r r a t e s .  designing  is lacking.  have  13.5  The  G e n e r a l l y good agreement  MEA,  to  kPa.  previously  solutions.  was  %;  103  e x c e p t a t h i g h C O 2 l o a d i n g s o f MEA AMP  to  kmol/m^; l i q u i d  CC>2 NaOH and from  9.5  t o 19.8  t o t a l pressure  predictions  m a t h e m a t i c a l model.  f l o w r a t e 11.1  flow rate  concentration  concentration  temperature  liquid  operating  information  that  full-length  a minimum number  plant.  d e t a i l s of  Two  and  special  hydrodynamic  coefficients,  hold-up)  for  the  effective physico-  system ( e . g . r e a c t i o n mechanism,  need not  be  known and  ( i i ) complex  Using  t h e PPT  performance of absorption  a given  full-length  absorber,  essential  using the p i l o t  or t o  p r e d i c t the the s p e c i f i c  i n f o r m a t i o n , c a n be  plant  model  (PPM) c o l u m n  b o t h c o l u m n s h a v e t h e same h y d r o d y n a m i c c o n d i t i o n s .  can in  the height  r a t e , which i s the  measured d i r e c t l y if  to size  be a c h i e v e d  by u s i n g t h e same t y p e a n d  size  of packing  t h e PPM a n d t h e f u l l - l e n g t h c o l u m n s a n d e n s u r i n g  end  and  wall effects are  a l s o be o p e r a t e d those  of  rate  was  then  PPT  which  obtained  column. from  p r o f i l e along  the performance  carbon  s o l u t i o n s of  dioxide  the  was  by  obtained.  the  velocities  gradient of  as  absorption the  fluid  The v a l i d i t y o f the height  full-length  absorbed from  that the  c o l u m n must  specific  determining  of  NaOH a n d AMP a t  g o o d a g r e e m e n t was  The  fluid  t h e PPM c o l u m n .  was d e m o n s t r a t e d  predicting  The PPM  a t t h e same s u p e r f i c i a l  the f u l l - l e n g t h  composition the  negligible.  This  column  a i r by  and in  aqueous  various operating conditions;  V  TABLE OF CONTENTS  ABSTRACT  i i  L I S T OF TABLES  ix  L I S T OF FIGURES  xi  ACKNOWLEDGEMENTS  '  xxi  1. INTRODUCTION  1  1.1 ACID GAS ABSORPTION BY CHEMICAL SOLVENTS  9  1.2 DESIGN OF CHEMICAL GAS ABSORPTION COLUMNS  13  1.3 RESEARCH OBJECTIVES  17  2. LITERATURE REVIEW  21  2.1 GAS ABSORPTION WITH CHEMICAL REACTION  21  2.2 REACTION OF C 0 SOLUTIONS  28  2  I N CAUSTIC AND AMINE  2.2.1 REACTION CHEMISTRY OF THE CAUSTIC - C 0 SYSTEM  28  2.2.2 REACTION CHEMISTRY OF C 0 SYSTEM  30  2  2  ~ AMINE  2.3 DESIGN OF PACKED ABSORBERS WITH CHEMICAL REACTION  ...32  2.3.1 EMPIRICAL DESIGN METHOD  43  2.3.2 THEORETICAL DESIGN METHOD  48  2.3.2.1 INFORMATION REQUIRED I N THEORETICAL CALCULATIONS  59  2.3.2.2 WEAK POINTS OF THEORETICAL DESIGN METHOD  69  2.3.3 DESIGN METHODS BASED ON MODELS 2.3.3.1 WEAK POINTS OF MODELS  LABORATORY 70  LABORATORY  THEORY  82  83  3.1 MATHEMATICAL MODEL  83  3.1.1 MODEL FORMULATION  85  3.1.2 COMPUTATIONAL PROCEDURE  91  3.2 PROPOSED PILOT PLANT TECHNIQUE FOR DESIGNING GAS ABSORBERS WITH CHEMICAL REACTION 3.2.1 THE PILOT PLANT TECHNIQUE  97 97  3.2.2 A SHORT-CUT PROCEDURE FOR PPT  108  3.2.3 V E R I F I C A T I O N OF PPT  112  SOLUBILITY OF C 0 SOLUTIONS  2  IN  2-AMINO-2-METHYL-1-PROPANOL  113  4.1 BACKGROUND INFORMATION  113  4.2 EXPERIMENTAL APPARATUS AND PROCEDURE  115  4.3 PREDICTIVE MODEL FOR C 0 SOLUTIONS  115  2  SOLUBILITY I N AMP  4.4 RESULTS AND DISCUSSION  PILOT PLANT AND EXPERIMENTAL PROCEDURE  120  131  5.1 THE PILOT PLANT ABSORPTION COLUMN  131  5.2 PILOT PLANT MODEL (PPM) COLUMN  143  5.3 REGENERATION COLUMN  148  5.4 A U X I L I A R Y EQUIPMENT  153  vii  5.5 PROCEDURE FOR ABSORPTION EXPERIMENTS USING THE FULL-LENGTH AND PPM COLUMNS  155  5.6 ANALYSIS OF SAMPLES  159  5.7 COLUMN TESTING  161  6. RESULTS AND DISCUSSION: COMPARISON BETWEEN FULL-LENGTH ABSORBER PERFORMANCE AND THEORETICAL PREDICTIONS 168 6.1 FULL-LENGTH ABSORBER PERFORMANCE  169  6.1.1 EFFECT OF OPERATING CONDITIONS  175  6.2 COMPARISON BETWEEN FULL-LENGTH ABSORBER PERFORMANCE AND THEORETICAL PREDICTIONS  183  6.2.1 SOURCES OF BASIC INFORMATION  183  6.2.2 COMPARISON  190  OF RESULTS  7. RESULTS AND DISCUSSIONS: COMPARISON BETWEEN FULL-LENGTH ABSORBER PERFORMANCE AND PREDICTIONS BASED ON PPT 210 7.1 V E R I F I C A T I O N USING R -CONCENTRATION y  DIAGRAM  7.2 V E R I F I C A T I O N USING PPT SHORT-CUT PROCEDURE 7.2.1 NaOH-C0  2  SYSTEM  7.2.2 C0 "AMP SYSTEM 2  210 220 220 231  7.3 DISCUSSION OF THE V E R I F I C A T I O N RESULTS  253  7.4 LIMITATIONS OF PPT  258  7.5 PRACTICAL IMPLICATIONS OF THE PPT  260  8. SUMMARY OF RESULTS AND CONCLUSIONS  264  9. RECOMMENDATIONS FOR FURTHER WORK  267  viii  NOMENCLATURE  270  REFERENCES  273  APPENDICES A.  A N A L Y S I S OF L I Q U I D  SAMPLES  286  B.  ERROR A N A L Y S I S  294  C.  COMPUTER PROGRAM L I S T I N G S  299  L I S T OF TABLES  Table Table Table Table Table  1.1: M a j o r i n d u s t r i a l p r o c e s s e s r e q u i r i n g gas t r e a t i n g  2  1.2: T y p i c a l c o m p o s i t i o n o f C a n a d i a n , T h a i a n d A m e r i c a n n a t u r a l g a s e s ( d r y b a s i s , m o l e %)  3  1.3: T y p i c a l c o m p o s i t i o n o f p r o d u c t g a s f r o m n a t u r a l gas steam r e f o r m i n g p r o c e s s  4  1.4: T y p i c a l c o m p o s i t i o n o f p r o d u c t g a s f r o m a coal gasification process, Flexicoker  4  1.5: C a p i t a l c o s t b r e a k d o w n f o r a c o m m e r c i a l s c a l e p l a n t p r o d u c i n g s y n t h e s i s gas (N +3H ) from s t e a m r e f o r m i n g f o r m a k i n g ammonia  8  2  Table  acid  1.6: Common a l k a l i n e solvents  2  r e a g e n t s used a s c h e m i c a l 10  T a b l e 2.1: C o m p a r i s o n r e s u l t s b e t w e e n a c t u a l a n d p r e d i c t e d h e i g h t f r o m t h e P o i n t m o d e l by Danckwerts and A l p e r  74  T a b l e 2.2: C o m p a r i s o n r e s u l t s b e t w e e n a c t u a l a n d p r e d i c t e d h e i g h t f r o m t h e P o i n t m o d e l by Laurent  75  T a b l e 4.1: E x p e r i m e n t a l S o l u b i l i t y Solution  of C 0  T a b l e 4.2: E x p e r i m e n t a l S o l u b i l i t y Solution  of C 0  T a b l e 4.3:  Comparison pK  1  2  i n 2 M AMP 121  2  i n 3 M AMP 122  o f present and p r e v i o u s l y r e p o r t e d  values  T a b l e 5.1: "Proper"  ....126  Design C r i t e r i a  of Packed  Columns  ...140  T a b l e 5.2: S y s t e m s s t u d i e d a n d number o f e x p e r i m e n t a l runs  157  T a b l e 5.3: O p e r a t i n g C o n d i t i o n s T a b l e 5.4: Gas a n d l i q u i d  158  f l o w r a t e s a t f l o o d i n g p o i n t . . . 165  T a b l e 6.1: E x p e r i m e n t a l r e s u l t s  f o r C0 -NaOH s y s t e m 2  171  X  T a b l e 6.2:  Experimental  r e s u l t s f o r C0 -MEA s y s t e m  T a b l e 6.3:  L i s t of o p e r a t i n g c o n d i t i o n s and f o r Run T9 (C0 -NaOH s y s t e m )  parameters  L i s t of o p e r a t i n g c o n d i t i o n s and f o r Run T22 (C0 -MEA s y s t e m )  parameters  2  185  2  T a b l e 6.4:  186  2  T a b l e 6.5: T a b l e 6.6:  T a b l e 6.7:  173  Comparison between the c a l c u l a t i o n r e s u l t s f r o m p r e v i o u s r e p o r t s and f r o m t h i s work  191  C o m p a r i s o n o f enhancement f a c t o r v a l u e s o b t a i n e d f r o m M e r c h u k e t a l . [ l 4 2 ] , Onda e t a l . [ 143] and Run T9  196  E f f e c t o f mass b a l a n c e on t h e h e i g h t p r e d i c t i o n f o r Run T9 (NaOH-C0 s y s t e m ) . O p e r a t i n g C o n d i t i o n s : gas r a t e = 1545 kg/m h; l i q u i d r a t e = 13.5 m /m h; NaOH c o n e . = 0.413 t o 2.0 kmol/m ; C 0 c o n e . = 1.0 t o 18.45 %; Column t e m p e r a t u r e = 15.0 t o 35.0 °C 206 2  2  3  2  3  2  T a b l e 6.8:  E f f e c t s o f m a j o r p a r a m e t e r s on t h e h e i g h t p r e d i c t i o n f o r Run T9 ( N a O H - C O o ) . O p e r a t i n g C o n d i t i o n s : gas r a t e = 1545 kg/m h; l i q u i d r a t e = 13.5 m /m h; NaOH c o n e . = 0.413 t o 2.0 k m o l / m ; C 0 c o n e . = 1.0 t o 18.45 %; Column t e m p e r a t u r e = 15.0 t o 35.0 °C 209 2  3  2  3  2  T a b l e 7.1:  A c t u a l and p r e d i c t e d h e i g h t s f o r a n a b s o r p t i o n tower removing C 0 f r o m a i r by c o n t a c t w i t h an a q u e o u s NaOH s o l u t i o n 217 2  T a b l e 7.2:  Verification  r e s u l t s f o r t h e PPT  procedure using  t h e NaOH-C0  2  short-cut  system  T a b l e 7.3:  Experimental  T a b l e 7.4:  V e r i f i c a t i o n r e s u l t s f o r PPT s h o r t - c u t p r o c e d u r e u s i n g t h e AMP-C0 s y s t e m 239 E f f e c t o f u n c e r t a i n t y a s s o c i a t e d w i t h Ry o n t h e predicted height using operating conditions of Run T9 ( N a O H - C O o ) . O p e r a t i n g c o n d i t i o n : gas f l o w r a t e = 14.8 m o l / m s; l i q u i d f l o w r a t e = 9.5 m /m h r ; _ i n l e t C 0 c o n c e n t r a t i o n = 18.4%; i n l e t [OH ] =2.0 k m o l / m 257  T a b l e 7.5:  r e s u l t s f o r C0 ~AMP s y s t e m  221  2  232  2  2  3  2  2  3  T a b l e 7.6:  Some o f h i g h - e f f i c i e n c y s o l v e n t s  262  XI  L I S T OF  Figure Figure Figure Figure  FIGURES  1.1: T y p i c a l f l o w s h e e t f o r g a s s w e e t e n i n g by chemical r e a c t i o n  11  1.2: C o n c e n t r a t i o n and t e m p e r a t u r e p r o f i l e s o f a t y p i c a l i n d u s t r i a l absorber  16  2.1: S c h e m a t i c o f g a s a b s o r p t i o n r e a c t i o n system  22  2.2: I n t e r f a c e b e h a v i o r chemical  with  chemical  f o r gas a b s o r p t i o n  with  reaction  24  Figure  2.3: P a c k e d a b s o r b e r  33  Figure  2.4: M a j o r d e s i g n p r o c e d u r e s f o r g a s a b s o r b e r s with chemical reaction 2.5: T y p i c a l v a p o r - l i q u i d e q u i l i b r i u m c u r v e s a t  34  Figure  40 °C o f C 0 - C h e m i c a l s o l v e n t s  38  2  Figure  2.6: S c h e m a t i c o f a p a c k e d a b s o r b e r  39  Figure  2.7: K a  47  Figure  2.8: A t y p i c a l p l o t o f I a s f u n c t i o n s o f I j a n d M parameters [70] 2.9: V a r i a t i o n o f t h e enhancement f a c t o r f o r C0 -MEA s y s t e m o b t a i n e d f r o m l a b o r a t o r y absorbers  Figure  G  v  values  of C0 -K C03 2  2  system [65]  2  Figure  2.10: G a s - s i d e mass t r a n s f e r c o e f f i c i e n t ,  56 57  k , G  as a f u n c t i o n o f g a s f l o w r a t e  61  Figure  2.11: H i g h - e f f i c i e n c y random p a c k i n g  62  Figure  2.12: S t r u c t u r e d p a c k i n g  63  Figure  2.13: A p p a r e n t r a t e c o n s t a n t o f C 0 - DEA s y s t e m r e p o r t e d by v a r i o u s r e s e a r c h e r s 2.14: S c h e m a t i c r e p r e s e n t a t i o n o f t h e P o i n t model  71  2.15: S c h e m a t i c r e p r e s e n t a t i o n o f C o m p l e t e modelling  77  Figure Figure  2  66  xii  Figure  2.16:  Sphere column  Figure  2.17:  Procedure f o r using modelling  Figure  3.1:  78 the  complete 81  Schematic d i a g r a m of a d i a b a t i c  packed  absorbers  86  Figure  3.2:  Differential  s e c t i o n of p a c k e d a b s o r b e r s  Figure  3.3:  S i m p l i f i e d f l o w c h a r t of the major c a l c u l a t i o n steps used i n the present  87  computer models  96 99  Figure  3.4:  Schematic of the P i l o t P l a n t Technique  Figure  3.5:  Figure  3.6:  Figure  4.1:  M a i n d e s i g n p r o c e d u r e s f o r gas absorbers with chemical reaction 105 Schematic r e p r e s e n t a t i o n to s i m u l a t e i n d u s t r i a l a b s o r b e r s u s i n g t h e PPT short-cut procedure 110 S o l u b i l i t y of C 0 i n a 2 M AMP s o l u t i o n a t 40 °C. ( S o l i d c i r c l e s - p r e s e n t experimental d a t a ; open c i r c l e s - R o b e r t s and M a t h e r [ 9 5 ] ; s o l i d l i n e s - p r e s e n t model) 123  Figure  4.2:  S o l u b i l i t y of C 0 i n a 3 M AMP s o l u t i o n a t 40 °C. ( S o l i d c i r c l e s - p r e s e n t experimental d a t a ; open c i r c l e s - R o b e r t s and M a t h e r [ 9 5 ] ; s q u a r e s - S a r t o r i and S a v a g e [ 7 1 ] ; s o l i d l i n e s - p r e s e n t model) 124  Figure  4.3:  S o l u b i l i t y of C 0 i n a 2 M AMP s o l u t i o n a t v a r i o u s t e m p e r a t u r e s . (Open c i r c l e s - 20 °C; s o l i d c i r c l e s - 40 °C; s q u a r e s - 60 °C; t r i a n g l e s - 80 °C; s o l i d l i n e s - p r e s e n t model)  128  S o l u b i l i t y of C0 i n a 3 M AMP s o l u t i o n a t v a r i o u s t e m p e r a t u r e s . (Open c i r c l e s - 20 °C; s o l i d c i r c l e s - 40 °C; s q u a r e s - 60 °C; t r i a n g l e s - 80 °C; s o l i d l i n e s - p r e s e n t model)  129  Figure  Figure  4.4:  4.5:  2  2  2  2  Solubility  of C 0  2  i n 2.5  M AMP  and  MEA  solutions  Xlll  at v a r i o u s t e m p e r a t u r e s . (Dotted, dashed and c h a i n d o t t e d l i n e s a r e t h e model p r e d i c t i o n s f o r t h e C0 ~AMP s y s t e m a t 4 0 , 60 a n d 80 °C, r e s p e c t i v e l y . S o l i d l i n e s a r e from t h e K e n t - E i s e n b e r g m o d e l [ 9 7 ] f o r t h e C0 -MEA system.) 130 2  2  Figure  5.1: S c h e m a t i c o f t h e p i l o t  plant  132  Figure  5.2: P i c t u r e s h o w i n g how t h e p i l o t p l a n t e q u i p m e n t f i t t e d into the Chemical Engineering Building 133  Figure  5.3: S c h e m a t i c o f t h e a b s o r p t i o n  Figure  5.4: D r a w i n g o f a c o l u m n s e c t i o n  135  Figure  5.5: S c h e m a t i c o f t h e r e d i s t r i b u t o r s  136  Figure  5.6: D r a w i n g o f t h e j o i n t b e t w e e n two s e c t i o n s  Figure  5.7: P i c t u r e o f t h e s a m p l i n g  column  ...134  system and t h e j o i n t  between two s e c t i o n s  141  Figure  5.8: S c h e m a t i c o f t h e s a m p l i n g  Figure  5.9: D r a w i n g o f t h e PPM c o l u m n  Figure  5.10: D i a g r a m s h o w i n g t h e g a s s a m p l i n g  Figure  5.11: P i c t u r e o f t h e PPM c o l u m n  Figure  5.12: P i c t u r e o f s a m p l i n g PPM  ...137  system  142 .....144 p o s i t i o n . . . 145 146  probes along t h e  column  Figure  5.13: S c h e m a t i c o f t h e r e g e n e r a t o r  Figure  5.14: P i c t u r e o f t h e r e g e n e r a t o r  1 47 149 .150  Figure  5.15: P i c t u r e o f t h e t o p p a r t o f t h e regenerator .151 F i g u r e 5.16: P i c t u r e o f t h e b o t t o m p a r t o f t h e regenerator 152 F i g u r e 5.17: P r e s s u r e d r o p s a s f u n c t i o n s o f g a s a n d l i q u i d flow r a t e . ( L i q u i d flow r a t e (kg/m s ) : s o l i d s q u a r e s - 2 . 8 0 2 ; open s q u a r e s - 4.160; open c i r c l e s - 6.740; s o l i d c i r c l e s - 8.112) ....164 2  XIV  Figure  Figure  5.18: G e n e r a l i z e d c o r r e l a t i o n f o r p r e s s u r e d r o p and f l o o d i n g c a l c u l a t i o n s s u g g e s t e d by Treybal  166  5.19: M e a s u r e d a n d p r e d i c t e d p r e s s u r e d r o p s  F i g u r e 6.1  167  E f f e c t o f C 0 l o a d i n g . The i n l e t C 0 l o a d i n g was i n c r e a s e d f r o m 0.0 (Run T13 - s o l i d c i r c l e s ) t o 0.118 (Run T14 - open s q u a r e s ) m o l C 0 p e r m o l MEA. O p e r a t i n g c o n d i t i o n s : g a s f l o w r a t e = 14.8 mol/m s; l i q u i d f l o w r a t e = 13.5 m /m h ; t o t a l MEA c o n c e n t r a t i o n = 2.0 k m o l / m ; i n l e t g a s C 0 c o n c e n t r a t i o n = 15.5% 177 2  2  2  2  3  2  3  2  Figure  6.2: E f f e c t o f g a s C 0 c o n c e n t r a t i o n . The i n l e t C 0 c o n c e n t r a t i o n was i n c r e a s e d f r o m 15.6 % (Run T16 - open s q u a r e s ) t o 19.1 % (Run T18 - s o l i d c i r c l e s ) . O p e r a t i n g c o n d i t i o n s : gas flow r a t e = 14.8 m o l / m s; l i q u i d f l o w r a t e = 9.5 m /m h ; t o t a l MEA c o n c e n t r a t i o n = 2.0 k m o l / m ; i n l e t C 0 l o a d i n g = 0.0 m o l C 0 / m o l MEA ...178 2  2  2  3  2  3  2  Figure  2  6.3: E f f e c t o f l i q u i d f l o w r a t e . The l i q u i d f l o w r a t e was i n c r e a s e d f r o m 9.5 (Run T18 - s o l i d c i r c l e s ) t o 13.5 (Run T15 - open s q u a r e s ) m /m s . O p e r a t i n g c o n d i t i o n s : g a s f l o w r a t e = 14.8 mol/m s; t o t a l MEA c o n c e n t r a t i o n = 2.0 k m o l / m ; i n l e t C 0 l o a d i n g = 0.0 m o l C 0 / m o l MEA; i n l e t g a s C 0 c o n c e n t r a t i o n = 19.5% .• ...179 3  2  2  3  2  2  2  Figure  6.4; E f f e c t o f a b s o r b e n t c o n c e n t r a t i o n . The t o t a l MEA c o n c e n t r a t i o n was i n c r e a s e d f r o m 2.0 (Run T18 s o l i d c i r c l e s ) t o 2.55 (Run T20 - open s q u a r e s ) kmol/m . O p e r a t i n g c o n d i t i o n s : gas f l o w r a t e = 14.8 m o l / m s; l i q u i d f l o w r a t e = 9.5 m /m h ; i n l e t C 0 l o a d i n g = 0.0 m o l C 0 / m o l MEA; i n l e t g a s C02 c o n c e n t r a t i o n = 1 9 . 1 % 180 3  2  3  2  Figure  2  2  6.5; E f f e c t o f g a s f l o w r a t e . The g a s f l o w r a t e was i n c r e a s e d f r o m 11.1 (Run T21 - open s q u a r e s ) t o 14.8 (Run T18 - s o l i d c i r c l e s ) m o l / m s . O p e r a t i n g c o n d i t i o n s : l i q u i d f l o w r a t e = 9.5 m /m h; i n l e t C 0 l o a d i n g = 0.0 m o l C 0 / m o l MEA; i n l e t g a s C 0 c o n c e n t r a t i o n = 19.1%; t o t a l MEA c o n c e n t r a t i o n = 2.0 k m o l / m 181 2  3  2  2  2  2  3  Figure  6.6; E f f e c t o f a b s o r b e n t t y p e . The s o l v e n t t y p e was c h a n g e d f r o m NaOH (Run T11 - s o l i d c i r c l e s ) t o MEA (Run T14 - open s q u a r e s ) . O p e r a t i n g c o n d i t i o n s : g a s f l o w r a t e = 14.8 mol/m s ; l i q u i d f l o w r a t e = 13.5 m /m h ; t o t a l a b s o r b e n t 2  3  2  XV  concentration concentration F i g u r e 6.7  = 2.0 k m o l / m ; i n l e t = 15.5% 3  g a s C02  182  P r e d i c t e d ( l i n e s ) and e x p e r i m e n t a l ( p o i n t s ) r e s u l t s f o r t h e C 0 - NaOH s y s t e m (Run T 9 ) : [ a ] Temperature p r o f i l e s f o r t h e l i q u i d ( s o l i d l i n e ) a n d g a s p h a s e s ( d o t t e d l i n e ) , Open s q u a r e s a r e the e x p e r i m e n t a l measurements o f t h e l i q u i d temperature; [b] concentration p r o f i l e s of C 0 (open c i r c l e ) a n d NaOH ( s o l i d c i r c l e ) ; [ c ] Enhancement f a c t o r 192 2  2  F i g u r e 6.8: P r e d i c t e d ( l i n e s ) a n d e x p e r i m e n t a l ( p o i n t s ) r e s u l t s f o r t h e C 0 - MEA s y s t e m (Run T 2 2 ) : [ a ] Temperature p r o f i l e s f o r t h e l i q u i d ( s o l i d l i n e ) a n d g a s p h a s e s ( d o t t e d l i n e ) , Open s q u a r e s a r e the e x p e r i m e n t a l measurements o f t h e l i q u i d temperature; [b] concentration p r o f i l e s of C 0 (open c i r c l e ) a n d l o a d i n g ( s o l i d c i r c l e ) ; [ c ] Enhancement f a c t o r 193 2  2  Figure  6.9: C o n c e n t r a t i o n o f C 0 i n t h e g a s p h a s e f o r Run T16. Open c i r c l e s r e p r e s e n t experimental measurements; t h e s o l i d l i n e and d o t t e d l i n e s denote t h e p r e d i c t e d v a l u e s u s i n g a column comprised of s i x and f i v e s e c t i o n s , r e s p e c t i v e l y . ( O p e r a t i n g c o n d i t i o n s : gas flow r a t e = 14.8 m /m h ; l i q u i d f l o w r a t e = 9.5 m /m h ; i n l e t C 0 l o a d i n g = 0.0 m o l C 0 / m o l MEA; i n l e t g a s C02 c o n c e n t r a t i o n = 15.5%; t o t a l MEA c o n c e n t r a t i o n = 2.0 kmol/m .) 198 2  3  3  2  2  2  2  3  Figure Figure Figure Figure Figure  6.10: C r o s s p l o t o f p r e d i c t e d a n d m e a s u r e d C 0 c o n c e n t r a t i o n s i n t h e gas phase  2  ...202  6.11: C r o s s p l o t o f p r e d i c t e d a n d m e a s u r e d NaOH c o n c e n t r a t i o n s i n t h e l i q u i d phase  203  6.12: C r o s s p l o t o f p r e d i c t e d a n d m e a s u r e d C 0 l o a d i n g i n t h e MEA s o l u t i o n  204  2  6.13: C r o s s p l o t o f p r e d i c t e d a n d m e a s u r e d t e m p e r a t u r e s i n t h e l i q u i d phase  205  7.1: A t y p i c a l p l o t o f C 0 mole r a t i o i n t h e g a s p h a s e a s a f u n c t i o n o f h e i g h t i n t h e PPM c o l u m n , Run S 5 . P o i n t s d e n o t e e x p e r i m e n t a l d a t a a n d t h e s o l i d l i n e i n d i c a t e s the best f i t using a t h i r d order polynomial equation. (Experimental c o n d i t i o n s : L i q u i d f l o w r a t e = 13.5 m /m h r ; a i r f l o w r a t e = 14.8 m o l / m s; t e m p e r a t u r e = 2 9 3 2  3  2  2  XVI  K; t o t a l p r e s s u r e = 101.3 k P a ; [ N a ] = 1.20 k m o l / m ; [OH ] = 0.75 t o 0.56 k m o l / m ; CO2 c o n c e n t r a t i o n = 4.1 t o 2.0%.) 211 +  3  Figure  3  7.2: C o m p a r i s o n o f R v a l u e s o b t a i n e d experimentally from model column t e s t s and from f i r s t p r i n c i p l e s . (Experimental conditions: L i q u i d f l o w r a t e = 13.5 m /m h r ; a i r f l o w r a t e = 14.8 m o l / m s ; t e m p e r a t u r e = 293 K; t o t a l p r e s s u r e = 101.3 k P a ; [ N a ] = 1.20 kmol/m .) 213 v  3  2  2  +  Figure  3  7.3: S p e c i f i c a b s o r p t i o n r a t e ( R ) a s a f u n c t i o n o f CO2 c o n c e n t r a t i o n i n t h e g a s p h a s e a n d OH c o n c e n t r a t i o n . The p o i n t s a n d s o l i d l i n e s a r e o b t a i n e d from e x p e r i m e n t s and t h e o r e t i c a l c a l c u l a t i o n s , r e s p e c t i v e l y . The d o t t e d l i n e denotes t y p i c a l R v a l u e s a l o n g t h e column f o r Run T 2 . ( E x p e r i m e n t a l c o n d i t i o n s : L i q u i d f l o w r a t e = 13.5 m /m h r ; a i r f l o w r a t e = 14.8 m o l / m s ; t e m p e r a t u r e = 293 K; t o t a l p r e s s u r e = 101.3 k P a ; [ N a ] = 1 .20 k m o l / m . ) 215 v  v  3  2  2  +  3  Figure  7.4: A c t u a l ( p o i n t s ) a n d p r e d i c t e d ( s o l i d l i n e s ) o f CO2 a n d NaOH c o n c e n t r a t i o n s i n t h e f u l l - l e n g t h a b s o r b e r f o r Run T 2 . ( E x p e r i m e n t a l c o n d i t i o n s : L i q u i d f l o w r a t e = 13.5 m /m h r ; a i r f l o w r a t e = 14.8 m o l / m s ; t e m p e r a t u r e = 293 K; t o t a l p r e s s u r e = 101.3 k P a ; [ N a ] = 1 .20 k m o l / m . ) 218 3  2  2  +  3  Figure  7.5: A c t u a l ( p o i n t s ) a n d PPT p r e d i c t e d v a l u e s o f C 0 ( s o l i d l i n e ) a n d NaOH ( d o t t e d l i n e ) concentrations i n the f u l l - l e n g t h absorber f o r Run T7* O p e r a t i n g c o n d i t i o n s : a i r f l o w r a t e = 14.8 m o l / m s; l i q u i d f l o w r a t e = 9.5 m /m h r ; CO2 c o n c e n t r a t i o n = 1 . 2 5 % ( t o p ) a n d 1 5 . 4 5 % ( b o t t o m ) ; [OH~] = 2 . 0 ( t o p ) a n d 0.14(bottom) kmol/m 223  2  2  3  2  3  Figure  7.6: A c t u a l ( p o i n t s ) a n d PPT p r e d i c t e d v a l u e s o f C 0 ( s o l i d l i n e ) a n d NaOH ( d o t t e d l i n e ) concentrations i n the f u l l - l e n g t h absorber f o r Run T 8 . O p e r a t i n g c o n d i t i o n s : a i r f l o w r a t e = 14.8 m o l / m s ; l i q u i d f l o w r a t e = 9.5 m /m h r ; C0 c o n c e n t r a t i o n = 1 . 7 % ( t o p ) a n d 18.6% ( b o t t o m ) ; [OH ] = 2 . 5 ( t o p ) a n d 0.18 (bottom) kmol/m 224  2  2  3  2  2  3  Figure  7.7: A c t u a l (solid  ( p o i n t s ) a n d PPT p r e d i c t e d v a l u e s l i n e ) a n d NaOH ( d o t t e d l i n e )  of C 0  2  XVll  concentrations i n the f u l l - l e n g t h Run T 9 . O p e r a t i n g c o n d i t i o n s : a i r 14.8 m o l / m s ; l i q u i d f l o w r a t e = C0 c o n c e n t r a t i o n =_1.0%(top) and 1 8 . 4 5 % ( b o t t o m ) ; [OH ] = 2 . 0 ( t o p ) 0.37(bottom) kmol/m 2  absorber f o r flow rate = 13.5 m /m h r ; 3  2  2  and  225  3  Figure  7.8: A c t u a l ( p o i n t s ) a n d PPT p r e d i c t e d v a l u e s o f C 0 ( s o l i d l i n e ) a n d NaOH ( d o t t e d l i n e ) concentrations i n the f u l l - l e n g t h absorber f o r Run T 1 0 . O p e r a t i n g c o n d i t i o n s : a i r f l o w c a t e = 14.8 m o l / m s; l i q u i d f l o w r a t e = 13.5 m /m h r ; C0 c o n c e n t r a t i o n = 1.75%(top) and 1 5 . 2 % ( b o t t o m ) ; [ O H ] = 1 . 5 ( t o p ) a n d 0.24 (bottom) kmol/m 226  2  2  3  2  2  -  3  Figure  7.9: Column t e m p e r a t u r e m e a s u r e d f r o m t h e f u l l - l e n g t h ( s o l i d c i r c l e s ) a n d PPM c o l u m n ( o p e n s q u a r e s ) f o r Run T 7 . O p e r a t i n g c o n d i t i o n s : a i r f l o w r a t e = 14.8 m o l / m s ; l i q u i d f l o w r a t e = 9.5 m /m h r ; C 0 c o n c e n t r a t i o n = 1.25% ( t o p ) a n d 15.45% ( b o t t o m ) ; [OH ] = 2 . 0 ( t o p ) a n d 0.14 (bottom) kmol/m 227 2  3  2  2  3  Figure  7.10: Column t e m p e r a t u r e m e a s u r e d f r o m t h e f u l l l e n g t h ( s o l i d c i r c l e s ) a n d PPM c o l u m n (open s q u a r e s ) f o r Run T 8 . O p e r a t i n g c o n d i t i o n s : a i r f l o w r a t e = 14.8 m o l / m s; l i q u i d f l o w r a t e = 9.5 m /m h r ; C 0 c o n c e n t r a t i o n = 1 . 7 % ( t o p ) and 1 8 . 6 % ( b o t t o m ) ; [OH ] = 2.5 ( t o p ) a n d 0.18 (bottom) kmol/m 228 2  3  2  2  3  Figure  7.11:. Column t e m p e r a t u r e m e a s u r e d f r o m t h e f u l l l e n g t h ( s o l i d c i r c l e s ) a n d PPM c o l u m n (open s q u a r e s ) f o r Run T 9 . O p e r a t i n g c o n d i t i o n s : a i r f l o w r a t e = 14.8 m o l / m s ; l i q u i d f l o w r a t e = 13.5 m /m h r ; C 0 c o n c e n t r a t i o n = 1 . 0 % ( t o p ) and 18.45% ( b o t t o m ) ; [OH ] = 2 . 0 ( t o p ) a n d 0.37 (bottom) kmol/m 229 2  3  2  2  3  Figure  7.12: Column t e m p e r a t u r e m e a s u r e d f r o m t h e f u l l l e n g t h ( s o l i d c i r c l e s ) a n d PPM c o l u m n (open s q u a r e s ) f o r Run T 1 0 . O p e r a t i n g c o n d i t i o n s : a i r f l o w r a t e = 14.8 m o l / m s ; l i q u i d f l o w r a t e = 13.5 m /m h r ; C 0 c o n c e n t r a t i o n = 1 . 7 5 % ( t o p ) and 1 5 . 2 % ( b o t t o m ) ; [OH~] = 1 . 5 ( t o p ) a n d 0.24(bottom) kmol/m 230 2  3  2  2  3  Figure  7.13: Column p e r f o r m a n c e a t l o w l o a d i n g . MEA (Run T21 - open s q u a r e s ) v s AMP (Run T27 - s o l i d c i r c l e s ) . O p e r a t i n g c o n d i t i o n s : gas flow r a t e =  XVlll  11.1 mol/m^ s; liquid flow rate = 9 . 5 m-Vm hr; total amine concentration = 2.0 kmol/m; inlet gas C 0 concentration = 19.0%; inlet C 0 loading = 0.02 moles of C 0 / mole of amine 234 2  2  2  2  Figure  7.14: Column p e r f o r m a n c e a t h i g h l o a d i n g . AMP (Run T28 - s o l i d c i r c l e s ) v s MEA (Run T18 - open squares). Operating c o n d i t i o n s : gas flow rate = 14.8 m o l / m s ; l i q u i d f l o w r a t e = 9.5 m /m h r ; t o t a l amine c o n c e n t r a t i o n = 2.0 k m o l / m ; i n l e t g a s C 0 c o n c e n t r a t i o n = 19.15%; o u t l e t C 0 l o a d i n g = 0.583 m o l e s o f C 0 / m o l e o f amine 235 2  3  2  2  2  2  2  Figure  7.15: C 0 c o n c e n t r a t i o n p r o f i l e o f Run #S70 without a n t i f o a m i n g a g e n t ( o p e n c i r c l e s ) a n d Run #S94 with a n t i f o a m i n g a g e n t ( s t a r s ) . O p e r a t i n g c o n d i t i o n s : gas f l o w r a t e = 1 4 . 8 mol/m s; l i q u i d f l o w r a t e = 9.5 m /m h r ; t o t a l amine c o n c e n t r a t i o n = 2.0 k m o l / m 238 2  2  3  2  2  Figure  7.16: A c t u a l ( p o i n t s ) a n d p r e d i c t e d v a l u e s o f C 0 ( s o l i d l i n e ) and l i q u i d l o a d i n g ( d o t t e d l i n e ) i n t h e f u l l - l e n g t h a b s o r b e r f o r Run T 2 3 . O p e r a t i n g c o n d i t i o n s : gas flow r a t e = 1 4 . 8 m o l / m s ; l i q u i d f l o w r a t e = 9.5 m /m h r ; t o t a l AMP c o n c e n t r a t i o n = 2.0 k m o l / m ; i n l e t g a s C 0 c o n c e n t r a t i o n = 15.5%; i n l e t l i q u i d l o a d i n g = 0 m o l C 0 / m o l AMP 241 2  2  3  2  2  2  2  Figure  7.17: A c t u a l ( p o i n t s ) a n d p r e d i c t e d v a l u e s o f C 0 ( s o l i d l i n e ) and l i q u i d l o a d i n g (dotted l i n e ) i n t h e f u l l - l e n g t h a b s o r b e r f o r Run T 2 4 . Operating c o n d i t i o n s : gas flow r a t e =14.8 m o l / m s ; l i q u i d f l o w r a t e = 9 . 5 m /m h r ; t o t a l AMP c o n c e n t r a t i o n = 2.0 k m o l / m ; i n l e t g a s C 0 c o n c e n t r a t i o n = 15.5%.; i n l e t l i q u i d l o a d i n g = 0.147 m o l C 0 / m o l AMP 242 2  2  3  2  2  2  2  Figure  7.18: A c t u a l ( p o i n t s ) a n d p r e d i c t e d v a l u e s o f C 0 ( s o l i d l i n e ) and l i q u i d l o a d i n g (dotted l i n e ) i n t h e f u l l - l e n g t h a b s o r b e r f o r Run T 2 5 . Operating c o n d i t i o n s : gas flow r a t e =14.8 m o l / m s ; l i q u i d f l o w r a t e = 9.5 m /m h r ; t o t a l AMP c o n c e n t r a t i o n = 2.0 k m o l / m ; i n l e t g a s C 0 c o n c e n t r a t i o n = 18.9%; i n l e t l i q u i d l o a d i n g = 0.152 m o l C 0 / m o l AMP 243 2  2  3  2  2  2  2  Figure  7.19: A c t u a l (solid  ( p o i n t s ) and p r e d i c t e d values of C 0 l i n e ) and l i q u i d l o a d i n g (dotted l i n e ) 2  XIX  i n t h e f u l l - l e n g t h a b s o r b e r f o r Run T26. O p e r a t i n g c o n d i t i o n s : gas f l o w r a t e =14.8 m o l / m s; l i q u i d f l o w r a t e = 9.5 m /m h r ; t o t a l AMP c o n c e n t r a t i o n = 2.0 k m o l / m ; i n l e t gas CO2 c o n c e n t r a t i o n = 18.65%; i n l e t l i q u i d l o a d i n g = 0.022 mol C 0 / m o l AMP 244 2  3  2  2  2  Figure  7.20:  A c t u a l ( p o i n t s ) and p r e d i c t e d v a l u e s o f CO2 ( s o l i d l i n e ) and l i q u i d l o a d i n g ( d o t t e d l i n e ) i n t h e f u l l - l e n g t h a b s o r b e r f o r Run T27. • O p e r a t i n g c o n d i t i o n s : gas f l o w r a t e =11.1 m o l / m s; l i q u i d f l o w r a t e = 9.5 m /m h r ; t o t a l AMP c o n c e n t r a t i o n = 2.0 k m o l / m ; i n l e t gas CO2 c o n c e n t r a t i o n = 19.0%; i n l e t l i q u i d l o a d i n g = 0.021 mol C 0 / m o l AMP 245 2  3  2  2  2  Figure  7.21:  A c t u a l ( p o i n t s ) and p r e d i c t e d v a l u e s o f CO2 ( s o l i d l i n e ) and l i q u i d l o a d i n g ( d o t t e d l i n e ) i n t h e f u l l - l e n g t h a b s o r b e r f o r Run T30. O p e r a t i n g c o n d i t i o n s : gas f l o w r a t e = 11-1 m o l / m s; l i q u i d f l o w r a t e = 13.5 m /m h r ; t o t a l AMP c o n c e n t r a t i o n = 2 . 0 kmol/m ; i n l e t gas CO2 c o n c e n t r a t i o n = 19.0%; i n l e t l i q u i d l o a d i n g = 0.29 mol C 0 / m o l AMP ......246 2  3  2  2  2  Figure  7.22:  Column t e m p e r a t u r e m e a s u r e d f r o m t h e f u l l l e n g t h ( s o l i d c i r c l e s ) and PPM c o l u m n (open s q u a r e s ) f o r Run T23. O p e r a t i n g c o n d i t i o n s : gas flow r a t e =14.8 m o l / m s; l i q u i d f l o w r a t e = 9.5 m /m h r ; t o t a l AMP c o n c e n t r a t i o n = 2.0 k m o l / m ; i n l e t gas CO2 c o n c e n t r a t i o n = 15.5%; i n l e t l i q u i d l o a d i n g = 0 mol C 0 / m o l AMP^ 247 2  3  2  2  2  Figure  7*23: Column t e m p e r a t u r e m e a s u r e d f r o m t h e f u l l l e n g t h ( s o l i d c i r c l e s ) and PPM c o l u m n (open s q u a r e s ) f o r Run T24. O p e r a t i n g c o n d i t i o n s : gas f l o w r a t e = 14.8 m o l / m s; l i q u i d f l o w r a t e = 9.5 m /m h r ; t o t a l AMP c o n c e n t r a t i o n = 2.0 k m o l / m ; i n l e t gas C 0 c o n c e n t r a t i o n = 15.5%; i n l e t l i q u i d l o a d i n g = 0.147 mol C 0 / m o l AMP 248 2  3  2  2  2  2  Figure  7.24:  Column t e m p e r a t u r e m e a s u r e d f r o m t h e f u l l l e n g t h ( s o l i d c i r c l e s ) and PPM c o l u m n (open s q u a r e s ) f o r Run T25. O p e r a t i n g c o n d i t i o n s : gas f l o w r a t e = 14.8 m o l / m s; l i q u i d f l o w r a t e = 9.5 m /m h r ; t o t a l AMP c o n c e n t r a t i o n = 2.0 k m o l / m ; i n l e t gas C 0 c o n c e n t r a t i o n = 18.9%; i n l e t l i q u i d l o a d i n g = 0.152 mol C 0 / m o l AMP 249 2  3  2  2  2  2  XX  Figure  7 . 2 5 : Column t e m p e r a t u r e m e a s u r e d f r o m t h e f u l l l e n g t h ( s o l i d c i r c l e s ) a n d PPM c o l u m n (open s q u a r e s ) f o r Run T 2 6 . O p e r a t i n g c o n d i t i o n s : g a s f l o w r a t e = 14.8 m o l / m s; l i q u i d f l o w r a t e = 9.5 m /m h r ; t o t a l AMP c o n c e n t r a t i o n = 2.0 k m o l / m ; i n l e t g a s C 0 c o n c e n t r a t i o n = 18.65%; i n l e t l i q u i d l o a d i n g = 0.022 mol C 0 / m o l AMP 250 2  3  2  2  2  2  Figure  7.26: Column t e m p e r a t u r e m e a s u r e d f r o m t h e f u l l l e n g t h ( s o l i d c i r c l e s ) a n d PPM c o l u m n (open s q u a r e s ) f o r Run T 2 7 . O p e r a t i n g c o n d i t i o n s : g a s f l o w r a t e = 11.1 m o l / m s; l i q u i d f l o w r a t e = 9.5 m /m h r ; t o t a l AMP c o n c e n t r a t i o n = 2.0 kmol/m* ; i n l e t g a s C 0 c o n c e n t r a t i o n = 19.0%; i n l e t l i q u i d l o a d i n g = 0.021 mol C 0 / m o l AMP 251 2  3  2  2  2  2  Figure  7.27: Column t e m p e r a t u r e m e a s u r e d f r o m t h e f u l l l e n g t h ( s o l i d c i r c l e s ) a n d PPM c o l u m n (open s q u a r e s ) f o r Run T 3 0 . O p e r a t i n g c o n d i t i o n s : g a s f l o w r a t e = 11.1 m o l / m s; l i q u i d f l o w r a t e = 13.5 m /m h r ; t o t a l AMP c o n c e n t r a t i o n = 2.0 k m o l / m ; i n l e t g a s C 0 c o n c e n t r a t i o n = 19.0%; i n l e t l i q u i d l o a d i n g = 0.29 mol C 0 / m o l AMP 252 2  3  2  2  2  2  XXI  ACKNOWLEDGEMENTS  The efforts  completion  of  this  thesis  owes  I would l i k e  o f many i n d i v i d u a l s .  deeply  t o the  t o thank  them  as  follows:  *  Dean  Axel  Meisen  and  Dr.  C.  Jim Lim  s u p e r v i s i o n , continuous guidance, wise  for  their  suggestions  and  encouragement; *  The  faculty  Chemical  members  Engineering  assistance  supporting  Department,  i n many ways  work was b e i n g *  and  staff  UBC,  at  for  the their  o v e r t h e d u r a t i o n when  this  completed;  My p a r e n t s , b r o t h e r s a n d  sisters  for their  continuous  l o v e and encouragement.  The and  financial  Engineering  support provided  Research  Council  by t h e N a t u r a l o f Canada  is  Science  gratefully  acknowledged.  Finally, and  I want t o t h a n k  understanding over  t h e p a s t few  encouragement and c o n f i d e n c e the success of t h i s  my w i f e C h r i s t i n e  thesis.  for her love  y e a r s . Her  continuous  i n me a r e more t h a n v i t a l  to  1  CHAPTER 1 INTRODUCTION  Most  natural  refineries,  and  gas  many  absorption processes H S)  from  2  processes 1.1  their  streams these  streams  [1-12].  a c i d gas  treating  t y p i c a l compositions  a r e shown i n T a b l e s  removed b e f o r e t h e s t r e a m s  1.2  the case  gases  t o 1.4.  [121,  trillion  f t ) and 3  n a t u r a l gas worldwide, worldwide  are  2.0  more  respectively.  As c a n  industrial in  Table gas  be s e e n  from be  produced  3  of  1990  0.14 m  of the  world's  sources, the m a j o r i t y  than  (The  i s one  amounts  trillion  being  2  c a n be u t i l i z e d o r m a r k e t e d .  significant  122],  major  C0 ,  a c i d g a s e s have t o  According to s t a t i s t i c s published i n Journal  gas  (such as  are l i s t e d  of n a t u r a l gas, which  contain  use  o f some c o r r e s p o n d i n g  most e x t e n s i v e and c l e a n e s t e n e r g y raw  Some  petroleum  plants  a c i d gases  t a b l e s , s u b s t a n t i a l amounts o f  In  plants,  chemical production f o r removing  t h a t need  [ 1 2 ] and  processing  and  2  H S. 2  i n the O i l &  trillion  (70.0  m  trillion  annually  proven  C0  in  ( e x c l u d i n g c o m m u n i s t c o u n t r i e s ) and  Gas (5.04  3  ft ) 3  Canada  n a t u r a l gas  of  of and  reserves  o f Canada a r e  1 . 1 : Major i n d u s t r i a l treating [ 1 2 ] .  Table  Acid gases to treating*  Process Hydrogen manufacture Petroleum desulfurization Coal liquefaction Chemicals Ammonia manufacture ( H / N mixture) Natural gas purification Pipeline gas L N G feedstock Syn gas for chemicals (H /CO) Coal gasification SNG (high Btu gas) Intermediate Bin gas Low Um gas Oil desulfurization Refinery fuel gas treating Ethylene manufacture (steam cracker gas treating) Flue gas desulfurization Utilities (electric) Refineries, etc. 2  processes  2  r e q u i r i n g a c i d gas  Common cleanup targets (% acid gas)  COj C 0 + H S + COS  <0.1%CO 10 ppm H S  COj C 0 + H j S + COS  < 16 ppm C 0 + CO 0.01 ppm H S  H S, C 0  <4 ppm H S ; < 1% C 0 1-2 ppm H j S ; <50 ppm C 0 <500 p p m C O ; < 0 . 0 1 ppm H S  2  2  2  2  2 l  COS, RSH, etc.  2  2  2  2  2  2  2  2  2  C O j , H S , COS :  2  500 ppm C O ; 0 . 0 1 ppm H S 2  HjS, C O j , COS H S, C 0  100 ppm I1 S 100 ppm l l S 100ppmH S ~1 ppm H S , 1 ppm C 0  SO,  90% removal  2  2  ll,S 2  2  2  2  2  2  3  Table  1.2: T y p i c a l natural  c o m p o s i t i o n of Canadian, Thai g a s e s ( d r y b a s i s , mole % ) .  Canada Compound  Ft.  S t . John  and American  Thailand  East Calgary  Erawan  "B"  Structure  US Wyoming  85.34 4.50 1 .50 0.25 0.48 0.83  54.40 0.35 0.12 0.01 0.04 0.00  63.34 10.61 5.17 1 .07 0.89 0.81  65.60 5.82 2.87 0.65 0.64 0.54  71.15 2.01 0.49 0.07 0.23 0.25  HS  2.41 4.37  13.77 29.12  17.20 0.00  23.06 0.00  17.56 3.76  N H  0.32 0.00  2.13 0.00  0.90 0.00  0.81 0.00  4.20 0.28  c c ic 2  3  c  4  5  co  2  2  2  2  * ** ***  from Younger [149] from M e i s e n [ 3 ] from A s t a r i t a e t a l . [ 1 2 ]  4  Table  1.3: T y p i c a l c o m p o s i t i o n o f p r o d u c t g a s f r o m gas s t e a m r e f o r m i n g p r o c e s s [ 1 2 ] .  Component  H N  20.4  2  CO CH Ar  Table  Mole % ( d r y b a s i s ) 58.3 18.3  2 2  co  natural  4  1.0 1 .7 0.3  1.4: T y p i c a l c o m p o s i t i o n o f p r o d u c t g a s f r o m a c o a l g a s i f i c a t i o n process, Flexicoker [12].  Component  H N  18.2 50.0  2 2  C0  CO CH  2  4  H S COS 2  NH  Mole % ( d r y b a s i s )  3  11.4  17.9 1 .4  1.0 0.02  0.06  5  2.7  and 68.6  typical  trillion  gas  containing  m,  respectively[121,  3  processing plant 10  to  20  %  o p e r a t i n g c o s t s of a c i d  which processes  of a c i d  gases,  q u a r t e r t o one h a l f o f t h e t o t a l c o s t  C0  2  of  heavy  C0  2  producing N H 3 ) , tons C0 / 2  one  [147].  f e e d s t o c k s which are mostly  or  coal.  s y n t h e s i s gas the C0  of  tons  o x i d a t i o n of  C0 / 2  heavy  t o be removed a r e s i g n i f i c a n t , for large plants  [100], worldwide  w e l l over  Furthermore, t h e i r more t h a n  10 %  estimated  the  per  of H  2  [19].  3  and  in  the  and N  for  2  fuel o i l .  The  amounts  made of  r a n g i n g up t o o v e r 20,000 A c c o r d i n g t o Weinberg  100 m i l l i o n  of H  2  and N H 3  et are  tons, respectively.  are s t i l l  growing  year. Stratton  and Teper  [148]  cost  1.22  from steam r e f o r m i n g  production rates  capital  as  light  t o n of s y n t h e s i s gas  annual production  160 b i l l i o n m  example,  (a m i x t u r e  t o n of s y n t h e s i s gas p r o d u c e d  by t h e p a r t i a l  t o n s / day  For  be  the  removal requirement ranges from  2  o f n a t u r a l g a s t o 2.49  al.  as h i g h as  r e m o v a l r e q u i r e m e n t s d e p e n d l a r g e l y on  hydrocarbons  p r o d u c t i o n of  2  and  hydrogen, v e r y l a r g e volumes  p r o c e s s u s e d and t h e p l a n t  C0  capital  or used as a f e e d s t o c k f o r o t h e r c h e m i c a l s such  ammonia. The  a gas  must be removed f r o m t h e p r o d u c t s t r e a m b e f o r e i t c a n  marketed  or  For  natural  the  gas r e m o v a l c a n be  In the manufacture  122].)  associated  with  the  at have C0  2  6  separation  u n i t f o r c o m m e r c i a l s y n t h e s i s g a s p l a n t s t o be up  t o 40 % o f t h e t o t a l c o s t  ( c . f . Table  1.5).  As c a n be  from these f i g u r e s , a s i g n i f i c a n t p o r t i o n of t h e efforts  i s directly  producing  associated  basic chemical  For  coal  for a  t o Penner  investment  the  operating  plants  of t h e  et a l . [83],  i s allocated  gasification  producing  in  high-Btu  to  t o t a l plant a b o u t 30 %  purification  section requires only costs  C O 2 separation  with  a c i d gas removal systems a l s o  s i z e a b l e percentage  According  processing  products.  gasification  s y n t h e t i c n a t u r a l gas,  seen  f o r the  account  investment. of the  plant  processes;  10 t o 15 %.  purification  the  Furthermore,  processes  are  substantial.  It of  i s therefore c l e a r that  t h e most i m p o r t a n t  processing  a v a r i e t y of basic chemicals. gas  t r e a t i n g , the  [12]  "...The in  steps  i s one  i n the productions  of  To s u m m a r i z e t h e i m p o r t a n c e o f  s t a t e m e n t by A s t a r i t a ,  Savage a n d  Bisio  may be q u o t e d :  major  hydrogen  natural  a c i d gas s e p a r a t i o n  gas  traditional  uses  manufacture, purification  of gas  ammonia are  expected  treating  for  production, to  experience  CO2  and  petroleum significant  removal refining, growth  and in  I  the  coming  than  decades.  industrial  The  activity  more  sulfurous  fuels.  Large  quantities  new  energy  sources.  increase  of  H2S,  as  COS.  treating  owning  shale,  gases  will  the  tar  have  and  sands to  contain  for  large  both  use  as  of  of  heavier  of  and  from  these  treating  will  of  CO2,  quantities  will  faster  feedstocks  gas  levels  changes  grow  be removed  troublesome  These  will  growing  complexity  will  technology  treating  to  and  the  gases  gas  other  sulfur  require  simultaneous  improved and  selective  treating.  In greater  the  case  depths  past.  New and  natural CO2.  in  These  Remote  production  high  natural  gas  for  improved  of  and  suitable  and  acid  acid  such  energy-efficient  coal,  Moreover,  amounts  of  a whole,  of  the  contaminants  gas  as  petroleum,  since  significant  importance  reliability."  is  or of  gas with  new  remote  expected  gases  pipelining  technology  more  gas,  will  gas  locations to  be  require  conversion (e.g.  on  are  than  more  LNG, or small  on  expected  was  highly  extensive to  offshore  emphasis  finds  the  case  contaminated  treating  to  methanol,  units  make or  permafrost) size  to  of  be in  at the with  them gasoline.  will  require  light  weight  8  Table 1.5: C a p i t a l c o s t breakdown f o r a commercial s c a l e p l a n t p r o d u c i n g s y n t h e s i s gas (N +3H ) from steam r e f o r m i n g f o r making ammonia [148]. 2  Plant section  2  C a p i t a l c o s t as % of the t o t a l  P r i m a r y and secondary reforming S h i f t and Methanation C0  2  removal  51.4 % 8.6  %  40.0 %  9  1.1  ACID GAS  Even  ABSORPTION BY CHEMICAL SOLVENTS  though  available,  over  absorption  [ 3 , 4,  many 90% 6,  are  listed  of 10,  s e p a r a t i o n r a t e s and overall costs  plants,  p l a n t s . The carbonate  treatment  use  chemical  11]. I t s p o p u l a r i t y stems from  most commonly u s e d c h e m i c a l  1.6  high low  solvents  [12].  e m p l o y e d i n more  especially  in  s o l u t i o n s are step  natural  than  60%  gas  of  the  processing potassium  sour  separator  absorbent  which e n t e r s the  from  the  against a counter-current a c i d gases are  o n l y used  i n d u s t r i a l a c i d gas  where e n t r a i n e d l i q u i d and  removed, f l o w s  leaves the  o f an  a chemical  gas,  generally  as  a  [12].  flow sheet  system u t i l i z i n g The  plants  are  s o l u t i o n s w i t h i n o r g a n i c or organic a d d i t i v e s [ 1 1 ] .  A typical  1.1.  processes  s e c o n d m a j o r g r o u p i s b a s e d on a q u e o u s  Sodium h y d r o x i d e final  removal  existing  Amine s o l u t i o n s a r e existing  gas  c a p a c i t i e s which lead to r e l a t i v e l y  [ 8 ] . The  i n Table  acid  b o t t o m of stream  a b s o r b e d and  t o p of t h e  is  shown i n  u n i t through  Figure  an  inlet  solid particulates the  absorber  are  upwards  of t h e l e a n s o l u t i o n .  the t r e a t e d  absorber.  removal  (or "sweet")  The gas  10  Table  1.6: Common a l k a l i n e solvents [12].  reagents  used  as  chemical  ^c—c—OH Monoethanolamine (MEA)  N—H \  H  yC—C—OH Diethanolamine (DEA)  Nr—H C—C—OH OH yQ—C—OH  Diisopropanolamine (DIPA)  Nr—H ^ C — C — C  I  OH yZ—C—O— P,fi'Hydroxyaminoethylether (DGA)  Nr—H \  Potassium carbonate (with promoters)  K C0  H  2  /  Potassium glycinate  C  3  -c/  Nr—H ^H  Caustic  C—C—OH  NaOH  OK  Figure  1.1:  T y p i c a l f l o w s h e e t f o r gas chemical reaction [13].  sweetening  by  12  The a c i d g a s  loaded ("rich") solution  f l o w s from  the  bottom of the a b s o r b e r and passes through t h e l e a n - r i c h  heat  exchanger  where  lean  solution.  I t then e n t e r s t h e t o p of t h e s t r i p p e r  i t i s heated  by  the hot,  recycled column.  some c a s e s , a f l a s h t a n k i s i n s t a l l e d u p s t r e a m o f exchanger  t o desorb d i s s o l v e d  the  h y d r o c a r b o n s a n d some o f  a c i d g a s e s by l e t t i n g down t h e p r e s s u r e o f t h e r i c h  Upon e n t r y  into the stripper,  g a s e s a r e f l a s h e d . The s o l u t i o n a counter-current  flow  of  water vapor  generated  r e b o i l e r . The s t r i p p i n g v a p o r removes most o f t h e a c i d gases from t h e r i c h  The o v e r h e a d condenser  passes  through  absorber.  a  the  acid  against i n the remaining  stripper  water vapor  through  i s condensed  a s r e f l u x . The l e a n s o l u t i o n ,  l e a v e s the bottom of t h e in  leaves the  of the  returned t o the s t r i p p e r  rich solution  the  stream.  mixture  where most  heat  stream.  some o f t h e a b s o r b e d  t h e n f l o w s downward  In  s t r i p p e r , exchanges heat w i t h  lean-rich  cooler  before  heat  exchanger  being  pumped  a and  which the  and  then  to  the  13  1.2 DESIGN OF CHEMICAL GAS ABSORPTION COLUMNS  I n g e n e r a l , t h e most i m p o r t a n t d e s i g n p r o b l e m absorption process it  of a  gas  i s p o s e d by t h e a b s o r p t i o n c o l u m n b e c a u s e  h a s t h e g r e a t e s t e f f e c t on t h e c a p i t a l a n d o p e r a t i n g c o s t  o f t h e p r o c e s s . A l t h o u g h many d i f f e r e n t c o n t a c t o r s have been d e v e l o p e d , have found  significant  gas-liquid  o n l y packed and t r a y  columns  i n d u s t r i a l u s e a s g a s a b s o r b e r s . More  r e c e n t l y , packed towers t h e m a r k e t due  types of  are  g a i n i n g an i n c r e a s i n g  t o t h e development  share  of h i g h - c a p a c i t y ,  of  high-  e f f i c i e n c y packings  [ 1 9 ] . T h e s e new p a c k i n g a r e a l s o u s e d t o  retrofit  units  existing  in  order  to  improve  column  capacities.  I n d u s t r i a l d e s i g n methods f o r s i z i n g p a c k e d towers  are given  by t h e NGPSA  absorption  E n g i n e e r i n g D a t a Book [ 1 3 ] ,  Maddox [ 4 ] , and K o h l a n d  Riesenfeld [15]. In addition,  l a t e s t data  f o r the  a n d methods  design  of  compiled  by  Newman [ 1 6 ] . T h e o r e t i c a l d e s i g n a p p r o a c h e s a r e p r e s e n t e d  by  i n d u s t r i a l gas  Astarita  treating  [17] and  p r o c e s s e s have  Danckwerts  i n d u s t r i a l and t h e o r e t i c a l  s e l e c t i o n and  the  been  [18]. Recently,  d e s i g n a p p r o a c h e s were  by A s t a r i t a , Savage a n d B i s i o  [19].  both  the  combined  14  N e v e r t h e l e s s , the design of  many gas absorbers  f o r example, amines or a c t i v a t e d hot potassium still 22,  l a r g e l y based on experience  124]  d e s p i t e the  fact  using,  carbonate  or " r u l e s of thumb"  that a b s o r p t i o n  with  chemical  sixty years.  (Hatta's  been s t u d i e d  work [23] was  f i r s t p u b l i s h e d i n 1928.) The main reason  this is  lack of  fundamental  transfer coefficients, and physico-chemical of c o n f i d e n c e which are [4,22].  design data,  i.e.  i s the  t h e o r e t i c a l design procedures  o f t e n complex  or based  instance,  using  on d o u b t f u l the  recommended by Danckwerts [18] and  by  as much  as a  theoretical predictions Maddox  theoretical  actual,  or  of fact,  many  required  is  efficiencies case  of  [4],  assumptions method  the data given by Beddome  f a c t o r of  feel  exercise  of a simple absorption  "Fixing  that in  number  is not  a simple  futility.  absorption  followed  the  computation  by  The  process chemical  of  would be  four [20]. exist  a c t u a l requirements  in the absorber  authors an  and  lack  theoretical  i n d i c a t e s that c o n s i d e r a b l e d i s c r e p a n c i e s , may  quote from  mass  [15,24]  [21], DeCoursey showed that the h e i g h t of absorbers overestimated  for  i n t e r f a c i a l areas, r e a c t i o n k i n e t i c s ,  p r o p e r t i e s . Another reason  i n the  For  f o r over  [14,  r e a c t i o n has  the  is  trays,  task. As  calculation is complicated reaction,  between [25].  of  the  This  number of  To either  a  matter  of  trays  rates  and  enough. In the  the  calculations  15  become  exceedingly  difficult".  to d e s i g n i n g packed  Evidence Figure  1.2  As c a n be s e e n ,  i s based  this  observation i s  on t y p i c a l  most o f t h e  absorber  d o e s n o t p e r f o r m a u s e f u l d u t y and of  the column.  statement  also  applied  towers.  supporting  which  A similar  provided  i n d u s t r i a l data  in  [15].  ( a p p r o x i m a t e l y 60  %)  r e p r e s e n t s an o v e r d e s i g n  16  Figure  1.2:  C o n c e n t r a t i o n and t e m p e r a t u r e p r o f i l e s of a t y p i c a l i n d u s t r i a l absorber [15].  17  1.3 RESEARCH OBJECTIVES  In the  the  basic  [22,  past  84].  For  some  amines,  absorption  provided  the  comprehensive  data  conditions  permit  systems  chemical  are  on  published  sound  comparisons  123].  Therefore,  good  required  to  the  confidence  validate to  industrial  Furthermore, processes and  are  higher  amines, transfer every  s t e r i c a l l y equipment  year.  2  simulation  of  become  possible  mass  transfer  (i.e  Unfortunately,  are with  performance in  the  incomplete theoretical  full-length theoretical  under  industrial  open or  literature.  insufficient  predictions  absorber  data  predictions  and  to  to [15, are give  design.  hindered  Enormous  data  C0 -  available.  chemical  (e.g.  and  physico-chemical  progressing  capacity  has  in  kinetics,  improvements  s t i l l  state  made  processes  2  steady  published  data  been  C0 -NaOH  reaction  absorber  rarely  has  absorption  like  design  are  progress  chemical  reaction etc.)  the  of  fundamental  properties,  of  much  accurate,  with  c o e f f i c i e n t s ,  Most  years,  understanding  conventional gas  few  in at  a  f a i r l y  solvents  amines)  structured  amounts  chemical  of  and  absorption  fast  (e.g.  rate. mixture  high-efficiency  packings) fundamental  are  New of mass  introduced  design  data  18  w o u l d be n e e d e d  to permit  the  c o m p l e t e s i m u l a t i o n of  such  absorbers.  The new  p r i n c i p a l o b j e c t i v e of t h i s t h e s i s  d e s i g n concept  for industrial  r e a c t i o n . T h i s new "Pilot  design concept  P l a n t T e c h n i q u e " o r PPT.  laboratory-scale, pilot  absorbers  with  i s subsequently  The  plant  i s to develop  concept  experiments  chemical called  the  depends o n l y  on  and  requires  minimum k n o w l e d g e of t h e a b s o r p t i o n s y s t e m . T h i s new concept  i s subsequently  length absorber air  i n which C0  was  2  removed  u s i n g aqueous s o l u t i o n s of sodium h y d r o x i d e  2-methyl-1-propanol  (AMP),  which i s  and  a sterically  are  used e x t e n s i v e l y  7 6 ] . To  narrow the  and  scope of  the  study,  from  hindered  were s e l e c t e d b e c a u s e  important  full-  2-amino-  amine. These a b s o r p t i o n systems industrially  a  design  v a l i d a t e d by a p p l y i n g i t t o a  (6.6 m h i g h )  a  they  [17,  18,  the research  was  r e s t r i c t e d only to packed columns.  This dissertation also d a t a on g a s profiles  and  for C0  of v a r i o u s experimental  reports extensive  experimental  l i q u i d c o n c e n t r a t i o n s as w e l l a s 2  - NaOH, C 0  h e i g h t s . In d a t a and  2  - MEA  and  C0  2  temperature  - AMP  a d d i t i o n , comparisons  absorbers  between  t h e o r e t i c a l p r e d i c t i o n s are  the  presented  19  for  C0 NaOH  the  C0 -MEA  and  _  2  fundamental d e s i g n data are  i s one  2  the  PPT  concept, the  solutions  had  to  solubility  data  were  typical  operating  This thesis a general  be  with  determined.  i s divided  of s u b j e c t s  verification  The  the  results  to  gas  details  of  the  which  5  is  3 . Chapter  r e p o r t s the study of C 0  Chapter  are  related  based  the development of the  are given i n Chapter  l e n g t h a b s o r b e r and 3,  reported  2 is  design procedure,  6 the r e s u l t s ,  in Chapter  AMP  i n t o nine c h a p t e r s . Chapter  reaction.  e x p e r i m e n t a l equipment and In Chapter  d i d not  in  2  Previously  and  to  the  review  chemical  c o n t a i n e d c h a p t e r and solutions.  of C 0  used  cover  p r e v i o u s l y p u b l i s h e d work, and  AMP  their  ranges of a b s o r b e r s .  t h e o r e t i c a l absorber  P l a n t Technique  of the systems  solubility  too l i m i t e d  literature  absorption  because  available.  Since the C0 ~AMP system validate  systems  2  presents  the  2  on  Pilot  4 is a  self  solubility  details  of  in the  the r e l a t e d operating procedures. w h i c h were o b t a i n e d f r o m t h e  t h e o r e t i c a l design procedure  discussed. of  C o n c l u s i o n s drawn f r o m t h i s  the  Chapter Pilot  7  presents  Plant  research project are  fullgiven the  Technique. summarized  in Chapter  8.  The  thesis  terminates  suggestions  for  f u t u r e work i n C h a p t e r  with 9.  a  summary  21  CHAPTER 2 LITERATURE REVIEW  The  contents  i n t h i s chapter  are general reviews  of the  s u b j e c t s r e l a t e d t o t h e d e s i g n a s p e c t s of gas a b s o r b e r s chemical reviews  2.1  reaction.  In  the l a t e r  a r e a l s o g i v e n where  chapters,  more  with  specific  necessary.  GAS ABSORPTION WITH CHEMICAL REACTION  Gas reactant  absorption  with chemical  reaction occurs  i n t h e gas phase and another  when  reactant i n the l i q u i d  phase a r e brought i n t o c o n t a c t . L e t A denote a r e a c t a n t the gas phase and B denote According  to  Astarita  f o l l o w i n g major  a reactant i n the l i q u i d  [17]  steps  and  occur d u r i n g  a  Danckwerts  from  phase.  [18],  the  (also  see  absorption  Figure 2.1):  (i)  T r a n s f e r of A from the the g a s / l i q u i d liquid  (ii)  i n t e r f a c e and d i s s o l u t i o n  into  to the  film.  Simultaneous the  g a s p h a s e by d i f f u s i o n  liquid  diffusion phase.  and c h e m i c a l  reaction  in  22  Gas Absorption with CheMical Reaction  Liquid  reaction products A  B  Mass t r a n s f e r  /  /  c  \ in ttrf«o<  Figure  2 . 1 : Schematic of gas a b s o r p t i o n r e a c t i o n system.  with  chemical  23  (iii)  D i f f u s i o n of a l l components  (iv)  concentration  gradients.  Heat t r a n s f e r  from the  p h a s e due  t o the  The  ( i i ) to ( i v ) take place  overall absorption  chemical  As  much h i g h e r  l i q u i d phase  s o l u t i o n and  simultaneously  rates  and  capacities  is  reaction.  after  absorption  gas  which  step ( i ) .  r e a c t a n t a c t s as a s i n k f o r  a r e s u l t , chemical  to  to the  r a t e i s s i g n i f i c a n t l y a f f e c t e d by  r e a c t i o n s i n c e the  s o l u t e A.  l i q u i d due  temperature gradient  c a u s e d by t h e h e a t s o f  Steps  i n the  processes  than p h y s i c a l  the the have  absorption  processes.  In g e n e r a l , the can  be  simplified  r e g i m e s [ 1 , 17-19, described are  slow  by 20,  reaction in  recognizing 23,  below.  reaction  reaction  Starting  r e g i m e and  regime,  p r o f i l e s are presented  in Figure  liquid  from  the to  corresponding 2.2.  film  reaction  regimes, which  [ 3 0 , 3 1 ] and  proceeding  their  the  characteristic  2 6 ] . These  i n d e t a i l by L e v e n s p i e l  summarized  chemical  chemical  Godfrey  are [32],  instantaneous the  extremely  concentration  24  | Gas film  Liquid I film I  1 Gas Liquid | s i film film LL i l 1 ^Reaction!  Reaction plane  IN.  1  >  plane J  Reaction zone  ®  Reaction only in film  j^High and constant  ® In film and main body  Phase inteffaceV Any value  r  1 1 1  )  !  — Gas  Figure 2.2:  \  i f  Reaction only in main body oi liquid  if  \ 1  1 1  Liquid —  I n t e r f a c e b e h a v i o r f o r gas a b s o r p t i o n chemical reaction [30],  with  25  Regimes fast, if  A and B. When t h e r e a c t i o n  the concentration  o f B, C , B  The a b s o r p t i o n  regime  controls  Regimes but  B,  rate  within the liquid gas  liquid  Regime  E  transfer  of  A through  film, film  reactant the  F.  In  (regime  the  For  gas  i s not extremely A i s completely  r e a c t i o n zone  i n case of low C  i n t e r f a c e i n case of high  and  enough  A),  film  rate.  When t h e r e a c t i o n  i s f a s t enough s o t h a t liquid  (regime  A a n d B f o r t h e r e g i m e A.  the o v e r a l l absorption  within the  i s high  B  film  i s d e t e r m i n e d p r i m a r i l y by t h e r a t e  the d i f f u s i o n  C and D.  i s not too high  interface i f C  of d i f f u s i o n of components the  very  the reaction plane l i e s e i t h e r within the l i q u i d  or a t t h e gas l i q u i d B).  i s instantaneous or  these cases  C  B  B  the  fast,  consumed  occurs  either  values or near values.  reaction  and  r a t e s a r e o f t h e same m a g n i t u d e . The r e a c t i o n  extends from t h e g a s - l i q u i d i n t e r f a c e t o w i t h i n t h e bulk the  mass zone of  liquid.  Regime gas  the  G. The r e a c t i o n  held  up i n t h e f i l m  A i n the film such that  i sstill  i s s l o w a n d t h e amount o f  dissolved  i s s m a l l . The mass t r a n s f e r r a t e  of  important but the o v e r a l l process  is  i t c a n be v i s u a l i z e d a s one o f p h y s i c a l  absorption  26  followed  by c h e m i c a l r e a c t i o n w i t h i n t h e b u l k  of the  liquid  phase.  Regime  H. The r e a c t i o n  is  mass t r a n s f e r r e s i s t a n c e s due  t o a low  e x t r e m e l y slow i n t h i s case. in  consumption r a t e of A  l i q u i d p h a s e . As a r e s u l t , uniform  the f l u i d  in  film are  negligible  by t h e r e a c t i o n  i n the  t h e e n t i r e l i q u i d phase  concentration  of  A  at  the  becomes  concentration  c o r r e s p o n d i n g t o t h e p a r t i a l p r e s s u r e above t h e l i q u i d . r a t e of a b s o r p t i o n w i t h i n the bulk  For  i s simply  a given  interface  equal t o the r a t e of  system and s e t of o p e r a t i n g rate,  and t h e  the shorter  column, the r e a c t i o n column from  reaction  regime  conditions, the  the distance  reaction plane  l i q u i d mass t r a n s f e r c o e f f i c i e n t ) .  the  (or the  between  higher  In a chemical  can change s i g n i f i c a n t l y  instantaneous reaction at  composition i n both phases. coefficient  of  This the  the top to  film  s i g n i f i c a n t l y a l o n g t h e column and t h e r e f o r e absorption of  reaction  the l i q u i d  f i l m on  the o v e r a l l  slow  reactant  to  makes  more c o m p l e x t h a n p h y s i c a l a b s o r p t i o n . in  along  causes the e f f e c t i v e liquid  the  absorption  r e a c t i o n a t the bottom because of t h e v a r i a t i o n of  transfer  The  liquid.  faster the reaction the  The  mass change  chemical The e f f e c t absorption  27  rate  is  factor"  often which i s  coefficient liquid [18].  for  presented  in  the  t e r m of  d e f i n e d as  the  r a t i o of  absorption  film coefficient  for  with the  chemical  an the  "enhancement liquid  reaction  purely physical  to  film the  absorption  28  2.2  REACTION OF  S i n c e the  CQ  absorption  amine s o l u t i o n s subject  has  IN CAUSTIC AND  2  is  Riesenfeld  the  present  described  2.2.1  thesis,  i n the  following  OH  THE  2  is  2  enters  and  importance,  the  [18],  [19],  discussed  systems w i l l kinetics  CAUSTIC - CQ  The  by  be  are  Kohl  used  in  briefly  SYSTEM  studied  system.  physically dissolved from  the  2  i n t o aqueous s o l u t i o n s  most w i d e l y  ions are  -  c a u s t i c . Once C 0  C0  into caustic  section.  of c a r b o n d i o x i d e  occurs,  s o l u t i o n and  can  their reaction  i s probably the  reaction  reviewed  these p r o c e s s e s are  REACTION CHEMISTRY OF  caustic  industrial  [ 1 5 ] . S i n c e t h e s e two  Absorption  the  major  extensively  i n d u s t r i a l a s p e c t s of and  of c a r b o n d i o x i d e  of  been  AMINE SOLUTIONS  the d i s s o c i a t i o n  solution,  two  reaction  of  Before in  the  of  the steps  occur:  C0  2  HCO3"  +  OH" +  =>  OH"  HC0 " =>  C0  = 3  According to A s t a r i t a [17], instantaneous,  (a)  3  whereas  +  H0  reaction  reaction  (b)  2  (a)  (b) may  be  regarded  proceeds at  a  as  finite  29  rate.  When  a  present, the since  the  (5.9X10 may  + 3  be  substantial reaction  amount  equilibrium  equilibrium constant m / k m o l a t 20  concentration  to  be  exceeds  The o v e r a l l  free  lies  hydroxide  far to  reaction  (b)  ° C ) . The b i c a r b o n a t e  3  assumed  of  of  10~  zero  the  right  is  large  concentration the  hydroxide  kmol/m [ 1 7 ] ,  2  reaction  whenever  is  3  which takes place  may  therefore  be  written as:  C0  the  2  +  20H"  =>  C0  +  H 0  (c)  2  r a t e o f w h i c h i s g i v e n by  rate  Pohoreck  =  and  k  2  [C0 ][OH~] 2  Moniuk  [111]  constant data f o r t h i s previously the  = 3  published  rate constant  system.  recently  They a l s o  i s not  only  a function  new  reviewed the  i n t h e open l i t e r a t u r e .  energy, but -also t h e c o n c e n t r a t i o n solution.  reported  They f o u n d  of t h e  of the i o n i c  rate data that  activation species  in  30  2.2.2 REACTION CHEMISTRY OF C Q  According t o  2  Astarita et  researchers, the reactions  t h e y have  a l . [19] as w e l l  as  other  governing t h e C0 -aqueous  amine  2  system a r e remarkably complex even though  - AMINE SYSTEM  and a r e n o t f u l l y  been s t u d i e d  f o r more  understood than h a l f  century. I t i sbelieved that there are three p r i n c i p a l  a  steps  governing the system:  Carbamate C0  formation: + 2RRNH  2  Bicarbonate C0  +  2  Carbamate  =  RRNCOO"  +  RRNH  (d)  + 2  formation: RRNH  +  H 0  =  2  HC0 ~  +  3  RRNH  (e)  + 2  reversion:  RRNCOO"  +  H 0  =  2  HC0 ~ 3  +  RRNH  (f)  where R s t a n d s f o r - C H O H a n d R d e n o t e s -H a n d - C H O H f o r 2  p r i m a r y and  secondary  amines, Danckwerts  4  2  amines,  [18] and  respectively.  4  For primary  A s t a r i t a et a l . [19] suggested  t h a t t h e c a r b a m a t e f o r m a t i o n r e a c t i o n p r e d o m i n a t e s when C0  2  loading i s less  amine.  On  t h a n a b o u t 0.5 m o l e s  the other  p r e d o m i n a t e s when t h e C 0  hand, 2  the  of C 0  carbamate  2  / mole  the of  reversion  l o a d i n g e x c e e d s a b o u t 0.5 m o l e s o f  31  CC>2 p e r  mole  bicarbonate  of  amine.  formation  carbamate;  the  inversely  the  importance  is  stable[7l].  relatively  concluded  the  rate  order less  For  with than  0.5  other  of  respect  the  both  moles  of  rate  a  of  the  s t a b i l i t y  of  the  formation  is  bicarbonate  s t a b i l i t y  the  carbamate.  rate since  of  bicarbonate  the as  MEA  be  CO2 and  as  of  when  amine,  other  results  approximated  amine  mole  carbamate  well  experimental  can  CO2 per  of  [18]  their  reaction  importance  the  unimportant  from  to  systems  of  Danckwerts  researchers overall  on  system,  -  is  quite  to  CC>2 MEA  formation  relative  depends  proportional  For  The  the  as  that f i r s t  loading  is  i.e.  [C0 ][RNH ] 2  such  as  2  secondary  amines  and  s t e r i c a l l y  * hindered Their  amines  carbamate  comparison rate  with  depends  on  ,  the  reaction  s t a b i l i t y that a l l  the  effect  of  each  for  these  systems  of  varies  MEA.  three  from  Therefore,  reactions.  reaction is  mechanisms  s t i l l  on  the  unclear  are  more  moderate the The  to  overall  low  by  reaction  understanding  overall with  complex.  reaction respect  of  rates to  the  * A s t e r i c a l l y h i n d e r e d amine i s d e f i n e d as a primary amine in which the amino group is attached to a t e r t i a r y carbon atom, or a secondary amine in which the amino group is a t t a c h e d to a secondary or a t e r t i a r y carbon atom [71].  32  r e a c t i o n m e c h a n i s m s and r a t e  constants  [ 1 9 , 4 3 , 120,  F o r more d e t a i l s on t h e r e a c t i o n c h e m i s t r y  of these  References  [ 1 8 ] , [ 1 9 ] and [ 8 7 ] s h o u l d be c o n s u l t e d .  2.3  OF  DESIGN  Packed packings  PACKED  A B S O R B E R S WITH C H E M I C A L  absorbers  are  vertical  of l a r g e s u r f a c e areas  may be e i t h e r c o - c u r r e n t packed absorbers  packed absorbers,  driving  the  t r i c k l e s down t h r o u g h  systems,  REACTION  columns  filled  ( F i g u r e 2 . 3 ) . The  with  operation  o r c o u n t e r - c u r r e n t . However,  are operated  maximum c o n c e n t r a t i o n  145].  counter-currently to forces.  absorbent  is  the packings  In  obtain  counter-current  distributed  thereby  most  over  creating a  and large  surface f o r c o n t a c t i n g with the gas.  The m a i n d e s i g n height of absorbers  the  tower.  The m a i n  with chemical  F i g u r e 2.4. Empirical  o b j e c t i v e s a r e t o f i n d the diameter  Routes design  d e s i g n methods  for  designing  r e a c t i o n a r e shown s c h e m a t i c a l l y  1, 2  method,  based  steps  and  3 in  F i g u r e 2.4  Theoretical  on l a b o r a t o r y  design  refer method  and gas in to and  models, r e s p e c t i v e l y .  Figure  2.3:  Packed absorber  [86]  34 DEFINITION OF PROCESS CONDITIONS - T o t a l flow r a t e s o f gas and - I n l e t and o u t l e t c o n d i t i o n s  liquid  SPECIFY GAS-LIQUID CONTACTING SYSTEM - Type and d e t a i l s o f p a c k i n g s OBTAIN PHYSICAL  INFORMATION  - D e n s i t i e s and v i s c o s i t i e s - G a s - l i q u i d e q u i l i b r i u m data DETERMINATION OF SUPERFICIAL VELOCITIES - Liquid side - Gas s i d e OBTAIN PHYSICAL GAS ABSORPTION  PARAMETERS  - Mass t r a n s f e r c o e f f i c i e n t s - I n t e r f a c i a l area - L i q u i d hold-up OBTAIN ADDITIONAL  INFORMATION  Diffusivities Solubilities Reaction k i n e t i c s DETERMINATION OF ENHANCEMENT FACTOR  DETERMINATION OF  (K^y)  ave DETERMINATION OF ABSORPTION RATE  *  .  DETERMINATION OF COLUMN HEIGHT  Figure  2.4: M a j o r d e s i g n p r o c e d u r e s chemical reaction.  f o r gas a b s o r b e r s  with  35  The 2.3.1  d e t a i l s of  e a c h method  will  described  in  Sections  t o 2.3.3.  Once t h e s p e c i f i c d e s i g n the  be  total  flow  rate  of  problem i s d e f i n e d i n terms of  each  phase,  conditions, a suitable gas-liquid selected.  In  general, there t y p e and  suggested  packings  that  good  and  outlet  c o n t a c t i n g system can  i s no  s e l e c t i n g the packing  inlet  be  specific criterion  for  However, T r e y b a l  [86]  size. should  have  the  following  characteristics:  1. L a r g e e f f e c t i v e g a s - l i q u i d c o n t a c t i n g 2. L a r g e  area.  voidage.  3. C h e m i c a l l y  inertness.  4. S t r u c t u r a l  strength to permit  easy h a n d l i n g  and  installation. 5. Low  The  cost.  next  design  s u c h as d e n s i t y determine  their  diameter;  this  and  step i s to obtain physical viscosity  superficial is  flooding conditions.  normally These  of both phases velocities based  on  and  information i n order the  pressure  c a l c u l a t i o n s can  be  to  column drop  or  performed  36  u s i n g t e c h n i q u e s s u g g e s t e d by F a i r techniques w i l l  [ 8 5 ] o r T r e y b a l [ 8 6 ] . The  be d e s c r i b e d i n some d e t a i l  i n Chapter  Before the d e t a i l e d c a l c u l a t i o n of the absorber  5.  height  c a n be u n d e r t a k e n , i t i s n e c e s s a r y t o know t h e  vapor-liquid  e q u i l i b r i u m d a t a o f t h e s y s t e m . The e q u i l i b r i u m  information  i s needed t o d e t e r m i n e condition  i n the  column w i l l  i f t h e r e i s a pinch  column. I f  n o t be a b l e  adjustments of  the  c o m p o s i t i o n s of equilibrium  process conditions  gas and  driving  liquid  force  in  the  Therefore,  (e.g. flow  etc.) are  i s also  equilibrium)  condition exists,  t o perform as expected.  information  concentration  such a  (or  rates,  necessary.  The  need  to  determine  the  order  to  calculate  the  absorber height.  E x t e n s i v e e q u i l i b r i u m d a t a have CO2 -  amine s y s t e m s .  Particularly  conducted at the U n i v e r s i t y of t h e i r c o - w o r k e r s . Among  been r e p o r t e d f o r t h e noteworthy  i s the  work  A l b e r t a by O t t o , M a t h e r  and  t h e i r many  some o f t h e s e d a t a a r e  i n References  s t u d i e s on  solubility,  [ 9 5 ] , [96] and  [101].  T h e s e d a t a a s w e l l a s t h e d a t a p r e v i o u s l y p u b l i s h e d by o t h e r r e s e a r c h e r s were w e l l  summarized i n  b o o k , "Gas P u r i f i c a t i o n " and C h a k r a v a r t y  K o h l and  [ 1 5 ] . R e c e n t l y , Austgen  [119] have  proposed  rigorous  Riesenfeld's et a l . [88] mathematical  37  models to p r e d i c t the e q u i l i b r i u m behavior  of a c i d gases  amine s o l u t i o n s . However, the d e v i a t i o n s between t h e i r predicted solubility r e s u l t s can  and  be a s h i g h  Chakravarty•[119]  previously  a s ± 60 %.  suggested  that  reported  of the causes of  commonly u s e d s o l v e n t s  The  next design  F i g u r e 2.6 together  with  the  al.  the  expressed driving  N N  in  A  mass  the  shows  one  typical  absorption  into  diagram  the column h e i g h t .  of a  that  will  equations. According flux  terms of  of A  t h e mass  at  packed  steady  be  column  used  in  t o Sherwood state  may  transfer coefficients  et be and  f o r c e s f o r each phase:  = G < Y A " YA,i>  (2.1)  = L < C , i " C *)  (2.2)  k  A  CO2  for  nomenclature  the d e s i g n  in  [138]  schematic  developing [26],  F i g u r e 2.5  curves  and  r e s e a r c h groups i s  step i s to determine  shows a  experimental  the wide v a r i a t i o n  the d e v i a t i o n .  vapor-liquid equilibrium  model  Austgen e t a l . [88]  s o l u b i l i t y d a t a r e p o r t e d by d i f f e r e n t  in  P  k  A  A  where N  A  kg  =  mass t r a n s f e r  flux  of the absorbed  =  g a s - s i d e mass t r a n s f e r  coefficient  component A  38  Figure  2.5: T y p i c a l v a p o r - l i q u i d e q u i l i b r i u m c u r v e s a t 40 of C C ^ - C h e m i c a l s o l v e n t s [138].  °C  Liquid  39  y  A , out  Packed Absorber  dZ  T"  c  B,out  »ft,in Gas  Figure 2.6:  Schematic  of a packed  absorber.  40  P  =  total  mole f r a c t i o n o f A i n t h e b u l k g a s  y  A  =  y  A  i =  pressure  mole f r a c t i o n o f A on t h e g a s - s i d e o f t h e g a s liquid  interface  k  L  =  effective  C  A  =  c o n c e n t r a t i o n of A i n the bulk  =  c o n c e n t r a t i o n o f A on t h e l i q u i d - s i d e o f t h e gas-liquid  The r e l a t i o n s h i p  at the  l i q u i d - s i d e mass t r a n s f e r  coefficient  liquid  interface.  gas-liquid  interface  i s assumed  to  obey H e n r y ' s l a w :  C ,i  =  A  where H  H  YA,i  P  denotes  a s s u m p t i o n may effects the  ^2.3)  Henry's n o t be  constant.  applied  of system n o n i d e a l i t i e s  v a l u e s of H as d e t a i l e d  The mass o v e r a l l mass driving  N  A  f l u x can transfer  f o r nonideal  the  above  systems,  c a n h o w e v e r be l u m p e d  i n Section  also  Although  into  6.2.1.  be w r i t t e n  coefficient,  the  i n terms  K Q , and  the  of  the  overall  f o r c e by r e a r r a n g i n g E q u a t i o n s 2.1 a n d 2.2:  - G <y K  p  A  - y *) A  (2.4)  41  KQ  i s given 1/K  G  by l/k  =  + l/(Hk )  G  l/k  =  L  w h e r e I d e n o t e s t h e enhancement  I  k °  =  denotes  L  without  L  the  factor  L  liquid-side reaction.  with height  mass  transfer  coefficient  The mass b a l a n c e f o r an  dZ c a n be w r i t t e n  element  as:  (2.5)  = K a P(y  (2.6)  v  T  G  A  v  where Gj  is  effective  interfacial  A  L  N a dZ = G d [ y / ( 1 - y ) ] A  y  + l/(HIk °)  k /k °  chemical  of column  G  A  - y *)dZ  A  A  the i n e r t  gas  area  molar  per  unit  flow  rate,  volume  a  v  is  of packing,  the and  i s t h e v a p o r - p h a s e m o l e f r a c t i o n o f component A w h i c h i s  in equilibrium  Rearranging  and  with the c o n c e n t r a t i o n  integrating  Equations  i n the l i q u i d  2.5  and  2.6  phase.  gives  yA,out z  t  =  G  i  {dyA/f G vP<i-y ) ^A-yA*)] K  a  2  A  YA, i n  (2.7)  42  In  the  traditional  Equation  design  2.5 i s s o m e t i m e s  "height of transfer  a  unit  transfer  method  rearranged unit  (HTU)"  f o r packed  columns,  as t h e p r o d u c t and  the  of  the  "number  of  (NTU)", i . e  (HTU)*(NTU) where HTU  =  [ G  T  / ( K  G  a  P)]  v  and YA,out NTU  /dy /[(i-y ) (y -y *)] 2  A  A  A  A  YA, i n  The HTU i s an i n v e r s e measure lower  i t s value,  represents for  t h e more  the t o t a l  efficient  number  a given absorption duty.  d e f i n i t i o n s are  only  of the packing  valid  the  e f f i c i e n c y ; the  packing.  of the t r a n s f e r  The  units  required  I t s h o u l d be n o t e d t h a t provided  KQ, a  v  and  NTU  these P  are  constant.  According written  as  to  Danckwerts  [ 1 8 ] , Equation  2.7  can  also  be  43  yA,out Z  =  t  Gj  (2.8)  dy /[R a (1-y ) ] 2  A  a  v  A  YA in r  where R unit  a  i s d e f i n e d as  i n t e r f a c i a l area.  derived  (The  r a t e of a b s o r p t i o n  d e t a i l e d e x p r e s s i o n of R  a  per will  i n S e c t i o n 2.3.2.)  Solving Equations because fluid  the s p e c i f i c  I i s a complex properties  and  2.7  or  2.8  is  usually  f u n c t i o n of the column concentrations,  s i g n i f i c a n t l y a l o n g the column.  The  hydrodynamics,  which  d e t a i l s of  c a l c u l a t i o n s of t h e enhancement f a c t o r w i l l  difficult  can  vary  theoretical  be e x p l a i n e d  on  page 50 t o 57.  The  following s e c t i o n s are  approaches f o r determining  2.3.1  reviews  the column  of t h r e e  different  height.  EMPIRICAL DESIGN METHOD  E m p i r i c a l design approach i s based  on  distillation  the  concepts  ( s e e Route# 1 o f F i g u r e  developed  for  and p h y s i c a l a b s o r p t i o n c o l u m n s .  the  design  By u s i n g  2.4) of this  44  approach,  the o v e r a l l  v o l u m e t r i c mass t r a n s f e r  ( K g a ) i s assumed t o be c o n s t a n t  a l o n g t h e packed column and  v  has  t o be  filled  obtained experimentally using  a column which  the form  The  experimental  of the average K a G  mean d r i v i n g  (K a ) G  v  data are  usually collected  force:  a v e  = G [y T  A f B  /(l-y  ) -  A f B  y , /(1-y A  T  z  where Z  e  i s the height  of the experimental  ) ^ d e n o t e s t h e l o g mean d r i v i n g  <yA-YA*>lm =  A f T  )]  <YA " YA*>lm]  p  column and ( y ^  t(YA-YA*)B- YA-yA* TVln[(y -y *) /(y -y *) ]  S u b s c r i p t B and T r e p r e s e n t  (  )  A  A  B  A  A  T  t h e bottom and t o p c o n d i t i o n s ,  r e s p e c t i v e l y . The v a l u e s o f ( K Q v ^ a v e o b t a i n e d t h i s way a  u s u a l l y c o r r e l a t e d as e m p i r i c a l  can  -  force,  m  parameters  in  v a l u e s on t h e b a s i s o f a l o g -  v  /t e  A  is  w i t h t h e same p a c k i n g a s t h e f u l l - l e n g t h c o l u m n t o be  designed.  y  coefficient  (such as flow r a t e s ) .  f u n c t i o n s of the The h e i g h t o f an  t h e n be c a l c u l a t e d by u s i n g E q u a t i o n  are  operating absorber  2.7.  Numerous s t u d i e s u s i n g t h i s a p p r o a c h h a v e been by K o h l a n d R i e s e n f e l d [ 1 5 ] a n d E d w a r d s [ 2 4 ] .  reviewed  45  Although extensively absorption  the  for  of  has  been  distillation  and  used  physical  with chemical  r e a c t i o n . When  the extent  of  r e a c t i o n i s high, which i s u s u a l l y thecase,  enhancement along  the design  approach  columns, i t u s u a l l y leads t o problems i n t h e case  of a b s o r p t i o n chemical  empirical  f a c t o r and  therefore  ( K a ) change G  v  the  appreciably  t h e column. A s t a r i t a e t a l . [19] and J o s h i e t a l .  [65]  r e c e n t l y p o i n t e d o u t t h i s p r o b l e m . To q u o t e f r o m A s t a r i t a e t a l . [19],  "  the assumptions  independent case  of fluid  of chemical  obtained rather different  unpredictable  showed t h a t  will strongly ways  and  transfer  are certainly that  depend cannot  be  not justified  the values  extrapolated  of  and in the  (KQ y)ave. a  parameters to  been obtained  Astarita  empirical  is constant  on all operating  they have  t h i s statement, using t h i s  mass  It follows  the ones for which  In s u p p o r t i n g  the  concentrations  absorption.  in this way  from  that  in  conditions ".  e t a l . [19] f u r t h e r  approach would  lead  to  l a r g e e r r o r s i n p r e d i c t i n g c o l u m n h e i g h t s . A s i l l u s t r a t e d by Figure  2.7,  the ( K a ) G  v  a v e  values  r e p o r t e d by Benson e t a l . [ 1 3 9 ] of magnitude.  Since  of  vary  t h e K2CO3-CO2  system  by more t h a n a n  the c a l c u l a t e d height  ( c f .  order  Equation  46  2.7)  depends d i r e c t l y  on t h e v a l u e s  associated  with  the height  associated  with  the K a  of 1.5  factor"  to 2.5  method i n o r d e r the  G  v  of K a , t h e u n c e r t a i n t y G  v  prediction i s values.  As  similar  a result,  i s commonly a p p l i e d  t o overcome t h e u n c e r t a i n t y  to  a  that  "safety  to this  design  associated  with  (K a ) G  v  ave oversized capital It  data  columns r e s u l t i n g costs.  is  difficult  therefore  systems.  T h i s may  lead to excessively  i n unnecessary expenditures  and o p e r a t i n g  e m p i r i c a l design reaction  [124, 125].  approach f o r  t o have  confidence  gas a b s o r p t i o n  with  in  of  the  chemical  F i g u r e 2.7: K a G  v  v a l u e s of C 0 - K C 0 3 system 2  2  [65].  48  2.3.2 THEORETICAL DESIGN METHOD  The  h e i g h t of  an a b s o r b e r  a l s o be c a l c u l a t e d by u s i n g v a l u e s of  the  absorber  are  specific known.  theoretically,  with  Equation  absorption  However,  to  information  chemical  reaction  may  2.8 p r o v i d e d t h a t  the  rate,  the  R , a  evaluate  regarding  along  these  values  the  column  h y d r o d y n a m i c s and p h y s i c o - c h e m i c a l p r o p e r t i e s o f t h e (diffusivities,  s o l u b i l i t i e s and r e a c t i o n  system  k i n e t i c s ) must  be  known ( s e e Route# 2 i n F i g u r e 2 . 4 ) .  THEORETICAL  DETERMINATION  Even  though  presented  before,  s a k e . The absorber  some  of  they a r e  mass t r a n s f e r  R  Q  the  following  r e p e a t e d here  rate  of A  at  equations for  were  convenience  any p o i n t  of  the  may be w r i t t e n a s :  R a dZ a  OF  v  = k P(y G  =  Equations  I k  A  - y  L°< A,i c  A f i  )a dZ v  " C *)a dZ A  v  2.9 and 2.10 c a n be r e a r r a n g e d a s :  (2.9) (2.10)  49  k  G (y  - y i>  p  =  Af  A  YA,i  0  - c *)  A f i  (2.11)  A  ^  A  into  2.11 a n d  Equation  gives;  (lk °  G ) =  H P+ k  p  L  k  From E q u a t i o n  +  p  I k  L°C *  < - > 2  A  L°0  I k +  YA, i = < G YA  can  L (c  = H P y  Substituting rearranging  I k  (2.13)  / dk °HP + k P) L  Q  2.9, t h e c o n c e n t r a t i o n  12  of A a t the  interface  a l s o be w r i t t e n a s :  Yk,i  = Yk ~ * / < G >  Substituting rearranging  R  a  < - >  Pk  2  a  2.14  into  Equation  L°0  / (lk°  and  gives  = G YA " * G k  2.13  Equation  14  P  k  £< G YA  P  k  P  HP  I k +  +  k  L  G > P  H  ...(2.15)  R  a  = {(k Py )(Ik °H) + ( k P y ) ( k ) G  A  L  G  A  G  (k )(k Py )  - ( k ) ( I k ° C * ) } / (lk °H + k ) ] } G  Therefore,  L  A  L  G  G  G  A  (2.16)  50  R  a  = {lk °(HPy L  To f i n d R ,  L  A  (2.17)  G  an i t e r a t i v e method must be u s e d s i n c e  a  enhancement f a c t o r i n t e r f a c e which  + IH(k °A )]}  - C *)/[1  A  depends  on t h e  a r e n o t known  r e s u l t , Equations  concentrations  and cannot  2.14 a n d 2.17  at  a r e c o u p l e d and need t o A  as a f i r s t  t h e enhancement  ^ and  A  are then c a l c u l a t e d . Equation R . a  The s e c o n d  Equation  iteration  f  i  = y  A  may  be  i s then used t o  factor evaluate from  A  a r e r e p e a t e d u n t i l Yh,i approximates  be  taken  f o r y ^ i i s then obtained  closely  a  that  °^  of  the  iteration.  ENHANCEMENT FACTOR  One o f determine  the  CALCULATION  most  important c a l c u l a t i o n  is  to  i s a function  of  a l l components  in  t h e enhancement f a c t o r , I , w h i c h  the p h y s i c a l and  c h e m i c a l p r o p e r t i e s of  the l i q u i d  f i l m . To  general, a  set  represent  2.17  2.14. The c a l c u l a t i o n s  the c u r r e n t previous  approximation  the  be m e a s u r e d . As  s o l v e d s i m u l t a n e o u s l y . For example, y approximation. C  the  of  calculate partial  simultaneous  steps  t h e enhancement  differential  diffusional  mass  factor  equations transfer  in  which and  51  chemical  r e a c t i o n along  According  to A s t a r i t a  represent  these  written  the  liquid  film,  [ 1 7 ] , the  need t o be  solved.  d i f f u s i o n equations  phenomena w i t h i n  the  liquid  p h a s e may  =  2  uVCj  +  a C j / 3t  (molecular = (convective + (accumulation) transport) transport)  +  rj  (2.18)  + ( f o r m a t i o n by chemical reaction)  r j denotes the r e a c t i o n r a t e of s p e c i e s j i n s i d e the In g e n e r a l ,  the  reaction  r a t e depends  c o n c e n t r a t i o n s of the r e a c t a n t s To for  o b t a i n the  The  and  enhancement f a c t o r ,  a l l species  i n the  type  of  liquid  chemical  w h i c h component A f r o m t h e gas l i q u i d by an  system w i l l  c a l c u l a t i o n . The  the  AB  =  equations  absorption  system  literature  k  2 A B C  C  which  i s t h e one  has in  p h a s e r e a c t s w i t h component B second-order r e a c t i o n . This  C  rate expression r  the d i f f u s i o n  to i l l u s t r a t e  =  AB  and  products.  t h e enhancement  reaction i s represented  A + »> B  local  the r e a c t i o n  solved.  irreversible  be u s e d  liquid  on t h e  h a v e t o be  r e c e i v e d t h e most a t t e n t i o n i n t h e  in the  be  i n the f o l l o w i n g form:  DjV Cj  film.  which  i s given  by:  by  factor  52  It  must  be  noted  that  r e l a t i o n s h i p between the the  r e a c t i o n and  the  there  is  not  necessarily t»  stoichiometric coefficient,  order  of  the  reaction  [18].  any ,  A B  According  t o A s t a r i t a [ 1 7 ] , E q u a t i o n 2.18  can  be  the  the  gas-liquid interface  f o l l o w i n g assumptions:  plane,  (ii)  surface  the  film  (i)  theory i s  element behaves r i g i d l y d u r i n g  steady state conditions  s i m p l i f i e d by  valid,  prevail in  which  its life  the  making  theory.  described  the p e n e t r a t i o n  However, a l l t h r e e  r e s u l t s as S i n c e the has  by  f a r as  the  film.  is  relatively  u s e d and  will  surface  give v i r t u a l l y  numerical r e s u l t s are  f i l m theory  b e e n more w i d e l y  theories  be  the  (u=0), ( i i i )  liquid  and  is  means  The  mass t r a n s f e r phenomena a c r o s s a g a s - l i q u i d i n t e r f a c e a l s o be  of  could renewal  the  same  concerned  [26].  easy to understand, used i n the  it  following  discussion.  The and be  e f f e c t of  the  r e a c t i o n p r o d u c t , C,  chemical properties insignificant.  c o m p o n e n t s A and  o f c o m p o n e n t s A and  T h e r e f o r e , the B can  be  2  D ( B  = 0  2  A  A  2  3 C / 9x ) 2  2  B  - *  A  A B  B  k C C 2  A  the  B are  differential  rewritten  D (3 C /ax ) - k C C  on  physical assumed  equations  to for  as:  (2.19) B  = 0  (2.20)  53  where x  is  the  distance  i n t e r f a c e . The b o u n d a r y  in  the  liquid  conditions for  film  Equations  from  the  2.19  and  2.20 a r e :  At  x = 0 C  A  = c  A,i  3C /3x = 0 B  At  x = 6  where 6 d e n o t e s t h e factor  is  equal  concentration established  I  At solution  the  to  analytical  the  gradient  film  =  of A t o  {-<3C /9x) A  present  Hoftijzer solution  x = 0  time,  set of  of  the  actual  the gradient  enhancement interface  which would  be  absorption:  }/(C  there  A f  i/6)  is  equations  [44,  which  t h i c k n e s s . The  ratio  i n purely physical  for this  K e v e l e n and  liquid  67]  no  exact  [18,  provided  r e l a t e s the  analytical  5 9 ] . However  Van  an  approximate  actual  enhancement  54  factor,  I , t o t h e enhancement f a c t o r  for the  instantaneous  I ,z  reaction,  a  I = [M{(I -I)/(I -1)}]°- /tanh[M{(I -l)/(I -l)}]°5  c c  06  0 0  00  5  (2.21)  where M  =(D k C *)/(k °) A  2  B  2  L  and (D C *)/U  I. = 1 +  B  B  However, t h i s e q u a t i o n an  iterative  efficiency,  A B  D C A  A f i  )  i s i m p l i c i t a n d c a n be s o l v e d o n l y by  method.  To  improve  the  computational  s e v e r a l e x p l i c i t e q u a t i o n s have been p r o p o s e d .  Porter [68]: I = 1 + (loo ~ D O ~ exp[-(v/M - D / d . - D ] }  (2.22)  Kishinevskii [69]: WM/p){l  1 = 1 + where  0 = \/U/(I -))  - exp(-O.65/M0)}  (2.23)  + exp{ (0.68/v/M) - ( 0 . 4 5 / M / ( I . - 1 ) ) }  a  DeCoursey [ 9 0 ] : I = [(M /(4(I 2  -  -1) )) + 2  0 0  [ M / d d . - l ) ) ]  Io.M/d.-l)  +1]°-  5  (2.24)  55  Wellek et a l . [ 8 9 ] : I  =  1 +  where 1  Alper  {1 1  [(I  +  -  B  D/dj  and  comparison  of  Wellek et these  s o l u t i o n s over wide  %.  1 ) ] -35} 1  (2.25)  .35)  a l . [ 8 9 ] a l s o made a equations  with  above e q u a t i o n s c a n  comprehensive  precise  r a n g e s of c o n d i t i o n s .  maximum d i f f e r e n c e s among t h e The  ( 1/1  = »/M/tanhv/M  [70]  the  -  numerical  They f o u n d  r e s u l t s were l e s s t h a n  therefore  be  used to estimate  enhancement f a c t o r f o r s l o w t o i n s t a n t a n e o u s r e a c t i o n to I ^  IooK I n  l a b o r a t o r y equipment  sphere columns, e t c . ) contacting r e s u l t s can  area, be  w h i c h has  a well-defined  10 the 1  cells,  gas-liquid experimental  equations provided  a l l  fundamental data are a v a i l a b l e .  Some o f t h e s e r e s u l t s  were  s u m m a r i z e d by  Danckwerts [18].  Alper  p l o t of  functions  I as  t y p i c a l values the  reversibly  I j and  [70]  gave a  \/M ( F i g u r e  from w e l l - d e f i n e d  shown i n F i g u r e  s y s t e m s i n w h i c h one  phase r e a c t the  of  of I o b t a i n e d  CO2-MEA s y s t e m a r e  For  from these  (I  (i.e. stirred  the p r e c i s e p r e d i c t i o n of the obtained  that  2.9  typical  2.8). absorbers  or  for  [131].  o r more c o m p o n e n t s i n t h e  w i t h one  Some  more l i q u i d  gas  reactants,  enhancement f a c t o r c a l c u l a t i o n i s even more c o m p l e x .  56  57  F i g u r e 2.9: V a r i a t i o n o f t h e enhancement f a c t o r f o r C O o - M E A system o b t a i n e d from l a b o r a t o r y a b s o r b e r s [131]. ( P o i n t s were f r o m e x p e r i m e n t a l m e a s u r e m e n t s a n d l i n e s were f r o m t h e o r e t i c a l p r e d i c t i o n s . )  58  DETERMINATION  After  OF COLUMN HEIGHT  the values  various points along obtained  by  of R  a  are determined t h e o r e t i c a l l y  t h e column,  integrating  the  Equation  column 2.8  height  at  can  numerically  be or  graphically.  Surprisingly, published  on  obtained  from  the  no  detailed  concentration  theoretical  measurements. T h e r e f o r e ,  comparisons and  _  2  2  temperature  predictions  such d e t a i l e d  f o r t h e C 0 N a O H a n d C0 -MEA s y s t e m s  have  and  profiles  pilot  comparisons a r e  i n Chapter  6.  been  plant made  59  2.3.2.1 INFORMATION REQUIRED IN THEORETICAL CALCULATIONS  As can of  be  seen from the p r e v i o u s  information are  r a t e , and  required  t h e r e f o r e the  before  tower  section, several  the s p e c i f i c  h e i g h t , can  kinds  absorption  be  determined  theoretically.  PHYSICAL  GAS  For  ABSORPTION  PARAMETERS  the p h y s i c a l gas  absorption extensive  r e s u l t s h a v e been r e p o r t e d and  1960's f o r  r i n g s and  on  of d i m e n s i o n l e s s  these  parameters  in  However, t h e d a t a and  Perry's  a  L  v  i n the  1950's  l i k e ceramic  Raschig  such as d a t a and  terms  R e y n o l d s number  (Re),  their correlations  Chemical  Engineers'  2.10,  reproduced  from  Reilly Perry's  [126].  t o t h r e e - f o l d v a r i a t i o n a t a g i v e n gas also  out For  Handbook,  shows t h a t t h e g a s - s i d e mass t r a n s f e r c o e f f i c i e n t has  t y p e of u n c e r t a i n t y has  with  a r e s u b s t a n t i a l as p o i n t e d  i n c l u d i n g H u d g i n s and  are  Handbook  uncertainties (errors) associated  correlations  by many r e s e a r c h e r s example, F i g u r e  k °and  T h e s e d a t a were c o r r e l a t e d i n  S c h m i d t number ( S c ) . T h e s e  [85],  G  conventional packings  Berl Saddles.  w e l l documented  k ,  experimental  a  two-  flow rate [126],  This  been o b s e r v e d  f o r the case  of  60  liquid-side  mass  transfer  coefficients  and  effective  i n t e r f a c i a l areas [ 3 6 ] .  A major reason f o r t h e b e h a v i o r a n d mass t r a n s f e r c o m p l e x a n d c a n n o t be correlations  of  dimensionless  involved  correlated  by  using  in  " .... flow  classical  For  the  newer,  favoured  by  available  i n the  in  it  predicted  seems  doubtful  packings  will  high-efficiency [ 3 7 ] , very  literature  2.12  show  structured  be  of  to  flow  ever  quote the  be  satisfactorily  such  little  as  predict  information  is  area.  high-efficiency  physical  packings  Sc  are  transfer  Figures  high-efficiency  the  Re,  which  t h e i r mass  respectively.  from  complicated  packings,  regarding  the  that  using  The  gas since  2.11  random  and  classical  obtained f o r the conventional packings  used  properties  of  packings,  correlations not  some  To  parameters  c o e f f i c i e n t s and e f f e c t i v e i n t e r f a c i a l and  the  by s i m p l y  parameters.  dimensionless  industry  i s that  phenomena i n p a c k e d a b s o r b e r s a r e  accurately  Sherwood e t a l . [ 2 6 ] , phenomena  uncertainties  should  absorption the  latter  61  Gas  Figure  2.10:  flow  rate  (relative  units)  G a s - s i d e mass t r a n s f e r c o e f f i c i e n t , f u n c t i o n o f gas f l o w r a t e [ 1 2 6 ] ,  k , G  as  a  62  Poll Ring  F i g u r e 2.11: H i g h - e f f i c i e n c y  M e t a l (ntalox  random p a c k i n g [ 1 9 ] .  Figure  2.12:  Structured  packing  [38].  64  packings  have much more  different  flow  and  efficiency  packings  interfacial  areas  conventional  ones.  complex  mass  transfer  usually  and lower  configuration  have  resulting  phenomena. much  pressure  higher  drops  The  in  high-  effective  compared  with  65  PHYSICO-CHEMICAL  For  the  PROPERTIES  case  of absorption  physico-chemical data reaction  such as  with  chemical  solubility,  t o be o b t a i n e d  by  difficult,  For  performing  still  for  than h a l f agreement  absorption  a century. on t h e  system can only which  are  i n t o amine  For instance,  reaction  into diethanolamine  that  conditions,  differ  Figure  2.13).  the  solutions kinetics  mechanism f o r  (DEA) w h i c h  prominent researchers  rate  be  often  constants,  studied  there  isa  is  under  by a s much a s a f a c t o r o f f o u r  no  the CO2 secondary  i n the  a g r e e on t h e r e a c t i o n m e c h a n i s m t o be s e c o n d o r d e r found  have  conditions.  understanding of the r e a c t i o n  alkanolamine. Although  they  and  i n a d e q u a t e [ 4 0 - 5 1 , 8 7 ] a l t h o u g h i t h a s been  more  general  and  inaccurate.  CO2 absorption  case of  o t h e r t h a n MEA, t h e  reaction  experiments  t i m e - c o n s u m i n g and  the  specific  f o r each system a t t h e p r e s c r i b e d  r e a c t i o n k i n e t i c s of a given  obtained  is  diffusivity  r a t e c o n s t a n t s a r e needed i n o r d e r t o c a l c u l a t e t h e  enhancement f a c t o r . These d a t a a r e h i g h l y  The  reaction,  field  reaction, certain [52] (see  Figure  2 . 1 3 : A p p a r e n t r a t e c o n s t a n t o f C O 2 DEA s y s t e m r e p o r t e d by v a r i o u s r e s e a r c h e r s [ 4 3 ] . -  67  For  the  new,  high-capacity  hindered amines, their  gas  very l i t t l e  r e a c t i o n mechanism and  To  r e a c t i o n which take possible  to obtain  these  data  to  place  and  the in  be  is  sterically  available  on  constants.  physical  solubilities  systems a l s o  for  presents  simultaneous d i f f u s i o n  the  liquid  these properties  m e t h o d s must t h e r e f o r e deduce  rate  with chemical reaction  f u r t h e r d i f f i c u l t i e s due  such as  information  measure d i f f u s i v i t i e s  absorption  solvents  phase.  and  It is  d i r e c t l y and  not  indirect  u s e d . A commonly u s e d m e t h o d i s t o  from  corresponding,  but  nonreacting  systems.  In v i e w of and  i t s similar configuration, molecular  electronic  structure,  nonreacting  gas  solubility  of C 0  V e r s t e e g and  N0  and  C0  2  2  is  2  to estimate  and 2  N0 the  often  diffusivity  i n amine s o l u t i o n s . Swaaij  [128]  i n v e s t i g a t e d the  i n a q u e o u s s o l u t i o n s o f a m i n e s and the  N0  T h e r e f o r e , the  be  and  C0  applied  2  was to  constant. estimate the  r a t i o of  and  the  physical  the  [127]  solubility other  "N 0 2  to:  of  organic  solubilities analogy"  physical solubility  aqueous a l k a n o l a m i n e s o l u t i o n s a c c o r d i n g  as  Laddha e t a l .  compounds. They f o u n d t h a t 2  used  volume,  of C 0  of may  2  in  68  (Physical  solubility  of C O 2 i n amine) = C;(N 0 2  Solubility  i n amine)  where Cj  =  solubility  (CO2  Versteeg  and Swaaij  used t h i s  [128,  [128] and  Versteeg  that their  the p r e v i o u s l y reported  findings.  E s t i m a t i o n methods f o r  a l . [129] in  results  also  aqueous covering  in  liquids  for  r e s u l t s agree w e l l  solubilities both  Charpentier a l . [129].  [39], Versteeg  and  reacting  s y s t e m s h a v e r e c e n t l y been r e v i e w e d  et  i n water)  o p e r a t i n g c o n d i t i o n s h a v e been p u b l i s h e d r e c e n t l y found  and  et  solutions. Their experimental  1 2 9 ] . They  of gases  solubility  water)/(N20  approach to estimate C O 2 d i f f u s i v i t i e s  alkanolamine industrial  in  and  diffusivities nonreacting  a n d s u m m a r i z e d by  and S w a a i j  with  [128] and  Morsi  Versteeg  69  2.3.2.2 WEAK POINTS OF THEORETICAL DESIGN METHOD  As  have  difficulties chemical it  of  complex  calculations.  information regarding  It  there  a r e two  t h e t h e o r e t i c a l approach.  and  major  i s therefore  restrictions.  Secondly,  t h e hydrodynamic  with  Firstly, i t  needs  properties  the physico-chemical properties of the  a l t e r n a t i v e design procedures major  above,  i n p r e d i c t i n g t h e height of a gas absorber  the absorber  system.  shown  reaction using  involves  detailed  been  very which  important are free  to  develop  of these  two  70  2.3.3  DESIGN METHODS BASED ON LABORATORY MODELS  S i n c e many d i f f i c u l t i e s a r e e n c o u n t e r e d i n t h e of  obtaining  computing previous  the  the  physico-chemical  enhancement  and  Laurent  models f o r d e s i g n i n g  on  assumption  interfacial  [58-60]  gas  l a b o r a t o r y models the  factors  as  s e c t i o n , Danckwerts and A l p e r  Charpentier  The  information  area,  R ,  rate  depends  a  36,  54-63].  The  laboratory absorbers  R  a  values  known p r e c i s e l y a n d c a n be scale  and  laboratory  with chemical  reaction.  2.4) a r e b a s e d  of absorption only  can  r a t h e r than theory.  hydrodynamic parameters i n t h e  i n the  two  on  the  hydrodynamics and t h e r e a c t a n t c o n c e n t r a t i o n s [18,  in  [ 1 8 , 3 6 , 5 5 , 56]  ( s e e Route# 3 o f F i g u r e  that the  and  mentioned  proposed  absorbers  process  be  per  unit  absorber  i n both phases  determined In doing  l a b o r a t o r y absorber  matched w i t h those  from  t h i s , the must  of the  be  full-  column.  POINT MODEL  The 59,  f i r s t model i s c a l l e d  61-64]. A schematic  "Point modelling"  model [ 1 8 , 55,  57-  representation of the p r i n c i p l e  of  i s shown  t h e Point  in  F i g u r e 2.14.  (Details  are  F i g u r e 2.14:  Schematic r e p r e s e n t a t i o n of P o i n t model [ 5 5 ] .  72  given  by D a n c k w e r t s and  Alper  [ 5 5 ] . ) The  absorption-reaction  i n t e r a c t i o n s are measured i n a s m a l l s t i r r e d c e l l , which a g a s - l i q u i d contactor two  stirrers  in  concentrations  the c e l l uniform.  simulating absorption, in  s u c h a way  that  t h o s e i n the showed  operating  the  i t s kg  the  order  and  cell  k ° L  values  s t i r r e r speeds.  the absorption can  be  rate  measured  per  for  are  of  k  and  G  can  be  are  liquid  model  t o be  D a n c k w e r t s and  values  and  this  has  correspond to purely p h y s i c a l absorption, v a r y i n g the  gas  t o use  stirred  absorber.  desired  steady s t a t e . There  keep the b u l k  In  full-scale  that  to  at  for  operated  the  same  Alper  various  compositions.  The  resulting R  i n t o Equation  2.8  to y i e l d  bulk  gas  values  a  the  are  k °,  which  L  obtained  area  i n the  and  bulk  then  kinetics  and  cell liquid  substituted  r e q u i r e d column h e i g h t .  D a n c k w e r t s and  Alper  physico-chemical  by met,  It is  shown t h a t t h i s method e l i m i n a t e s t h e n e e d f o r o b t a i n i n g reaction  as [55]  Once t h e s e c o n d i t i o n s a r e  unit interfacial  is  the  parameters  explicitly.  p r e d i c t i n g the packed  with  [55]  p e r f o r m a n c e of 12.7  mm  ceramic  h e i g h t s . Aqueous  NaOH was  T a b l e 2.1  that  shows  the  t e s t e d the a C0  absorber  2  Raschig  u s e d as  P o i n t model m  ID)  to  various  the a b s o r p t i o n  medium.  predicted  rings  (0.1  by  and  actual  heights  73  differed  by l e s s t h a n  t h i s model  9% i n a l l  was p e r f o r m e d  cases.  by L a u r e n t  Further  testing  [130] w i t h  the  same  s y s t e m . H o w e v e r , t h e p r e d i c t e d r e s u l t s were n o t a s good discrepancies for  o f up t o ±  20% o c c u r r e d .  the larger discrepancies  It  should  be  noted  in this  that  the  of  No r e a s o n was  and given  case.  Point  model  is  only  a p p l i c a b l e t o s y s t e m s where t h e r e a c t i o n s a r e f a s t enough t o take there  place  i s no  limitation of  in  reaction  in  f i l m near the the bulk  of  i n t e r f a c e so  that  the  This  liquid.  a r i s e s b e c a u s e t h e l i q u i d h o l d up p e r u n i t v o l u m e  the s t i r r e d  column.  the l i q u i d  cell  i s much  l a r g e r than that of the  packed  74  2.1:  Table  C o m p a r i s o n r e s u l t s between a c t u a l and p r e d i c t e d h e i g h t from P o i n t model by D a n c k w e r t s and Alper [55].  CBO = C O H "  PCO, x 10  (mol  (atm)  1- ) 1  1  -  Inlet  Outlet  Inlet  Outlet  0.39 0.52 0.58 0.28 0.62 0.60 0.55 0.52 0.55 0.46 0.46 0.58 0.53  0.29 0.42 0.46 0.10 0.19 0.08 0.19 0.20 0.08 0.10 0.13 0.13 0.26  4.6 4.1 4.6 5.2 7.6 10.3 6.0 5.0 10.6 7.8 7.8 10.2 5.3  3.8 3.3 3.6 3.6 4.0 6.2 3.1 2.2 7.0 5.0 5.2 6.7 3.0  out  r d(CBo)h =  )  in  430 410 430 970 1430 1430 1420 1430 1320 1310 1120 1130 1120  *  zaZ WL  (s  cm ) - 1  Packing height  Predicted height  (cm)  (cm)  Difference Error in material (%) balance (%)  48.0 48.0 48.0 108.0 163.0 163.0 163.0 163.0 143.0 143.0 123.0 123.0 123.0  46.3 44.1 46.3 104.0 154.0 154.0 153.0 154.0 142.0 141.0 121.0 122.0 121.0  +3.5 +8.1 +3.5 +3.7 +5.5 +5.5 +6.1 +5.5 +0.7 + 1.4 + 1.6 +0.8 +1.6  8.4 4.2 3.6 3.5 0.5 0.8 7.0 0.0 5.3 6.7 5.4 2.6 6.0  75  T a b l e 2.2: C o m p a r i s o n r e s u l t s b e t w e e n a c t u a l a n d p r e d i c t e d h e i g h t f r o m P o i n t m o d e l by L a u r e n t [ 1 3 0 ] .  Pcoi x 10 (aim)  2  "G (cms" ]  Inlet  7.5 7.5 6.9 6.9 6.9 7.6 7.5 10.9 7.5 7.4  6.2 3.2 2.9 5.5 7.3 2.5 2.8 2.0 2.6 4.2  1  C — C n (mollir ) B 0  0  1  f  0 U T  dcjo  JIN  <t>m //  Outlet  "L (cms" )  Inlet  Outlet  (scrn" )  0.4 0.01 0.05 0.6 0.75 0.4 0.45 0.5 0.3 0.4  0.5 0.5 0.23 0.23 0.23 0.5 0.23 0.23 0.5 0.5  0.60 0.60 0.59 0.59 0.59 0.30 0.30 0.30 0.28 0.28  0.52 0.55 0.52 0.47 0.42 0.27 0.24 0.24 0.25 0.23  654 578 1120 1102 1144 673 1096 1145 692 722  1  1  (m)  1.92  Predicted height (m)  Difference <%)  Error in materal balance (%>  1.72 1.52 1.84 1.81 1.88 1.77 1.80 1.88 1.82 1.90  10.4 20.8 4.2 5.7 2.1 7.8 6.2 2.1 5.2 1.0  9.9 25 4 3.5 2.4 11.9 6.7 0 4 5.9  76  COMPLETE MODEL  The  second,  modelling  previously  p u b l i s h e d method  i s b a s e d on s o - c a l l e d Complete  shown i n F i g u r e  2.15.  (Full details  of  absorber  modelling,  which i s  of"Complete  modelling  u s i n g sphere columns  a r e g i v e n i n R e f e r e n c e s 55 a n d  full-scale  c a n be  absorber  c o n s i s t i n g of spheres 2 . 1 6 ) . The  spheres  r e p r e s e n t e d by  and a c y l i n d r i c a l  a r e c o n n e c t e d by  each sphere, t h e r e i s a l i q u i d  In  a model  shell  (see  a r o d . On  60.)  The  column Figure  the top  of  the values  of  pool.  order to s i m u l a t e the  packed column,  o k  C  k  L  '  (L/G),  (a Z/L)  and  v  (a /f)  in  v  the  laboratory  a b s o r b e r must be t h e same a s t h o s e i n t h e f u l l - s c a l e 7  represents  the  hold-up  of  the  absorber.  c o n d i t i o n s c a n be a c h i e v e d by s e l e c t i n g t h e r i g h t for  the  shell  cylinder  (Z /Z ) t  column  m  should  Danckwerts of  (i.e  sphere  diameter). be a b o u t  diameter, pool The  5-10  [ 5 6 , 6 2 ] ) where t h e  t h e f u l l - s c a l e column  desired  t  and  Z  The  dimensions  "scaling  m  and m o d e l c o l u m n ,  above  dimension  ( a s , s u g g e s t e d by Z  column.  denote  ratio"  Alper the  and  and  height  respectively.  Figure  2.15:  Schematic [56].  r e p r e s e n t a t i o n of Complete  model Ii ng  78  Liquid inlet  0 3 cm dio. stainless" steel rod 8x0-3 cm dia. holes  70 cm  Liquid outlet  Figure 2.16:  Sphere column  [56].  79  This scaling (L /a m  v  m  )  ratio  makes the  value  f o r the l a b o r a t o r y absorber  of the  wetting  rate  small s i n c e i t can  be  shown that  Z /Z t  Since L/G  = (L/a )/(L /a  m  v  m  i s f i x e d , the gas  a l s o s m a l l . I f there are mean residence time of  V f m  )  (2.26)  flow r a t e i n the model column i s  r e a c t i o n s i n the bulk l i q u i d , liquid  i n both  the  columns must be  the  same. The mean r e s i d e n c e time can be w r i t t e n as:  t  = Z /L 7  Rearranging  a /7  V  m  m  (2.27)  m  2.26  and  2.27,  one  obtains  , A  T h i s i d e n t i t y of liquid  7 Z /L  Equations  = a  V  =  t  < - > 2  the i n t e r f a c i a l  ( a / 7 ) means that the v  area per  u n i t volume  r e s i d e n c e times of the  provide the  which occur  i n the  afore-mentioned column can  same bulk of  parameters  be simulated  environment f o r the l i q u i d . are  by the  matched,  the  model column  in  reactions  When a l l the  of  liquid  in both columns are the same. T h i s c o n d i t i o n must be met order to  28  of  the  full-scale without  any  80  assumption kinetics.  about  the  transfer  Furthermore,  no  mechanism  physico-chemical  or  reaction  information  is  needed.  The  procedure  industrial  f o r -using  D a n c k w e r t s [ 5 6 ] who  with  12.7  a string  mm of  10  out  with  no  i n these  m  to  various reaction  between the  r a t e s was  packed  m high)  the  and  each  measured scale  1 t o 2. T h e r e  u s u a l l y the case i n d e s i g n  known a p r i o r i ,  problems.  is  scale  Another weakness of t h i s model i s t h a t the h e i g h t  f u l l - s c a l e c o l u m n i s assumed t o be  i s not  by  experiments  However, the  about  A  Alper  s y s t e m s where  predicted  only  by  l i q u i d phase. In  w i t h i n ± 7 %.  e x p e r i m e n t s was  1.58  an  [60].  m ID c o l u m n  i n h e i g h t . The  the  2.17  presented  r i n g s (0.49  0.49  simulate  i n f o r m a t i o n on u s i n g t h e c o m p l e t e m o d e l f o r h i g h e r  ratios. the  was  a 0.1  i n the b u l k of  difference  t o t a l absorption ratio  simulated  spheres,  reactions occurred the  technique  ceramic Raschig  were c a r r i e d  case,  to  packed column i s o u t l i n e d i n F i g u r e  good i l l u s t r a t i o n of t h i s and  t h i s model  of  which  81  INDUSTRIAL PACKED COLUMN DETERMINE  SPECIFY Packing material Z. L, (G/L)  by experiments  CHOOSE 1^ To -  < X  & •-  match k  )  by experiments  S JP  GAS  FLOW RATE = L (G7L) M  -  ^&.-',\t.-'~<,-~  DETERMINE CONFINING TUBE DIAMETER  CHOOSE APPROPRIATE SIZED SPHERES  (To match k  G  )  o -•-' .  .- u  DETERMINE  , - 'N  POOL DIMENSIONS NO- ;\-,  (To match a^ bp  \  DETERMINE  IS fT CONVENIENTLY SIZED ? m sYES- .  V  L / a  v  /  COMPLETE MODEL OF THE PACKED COLUMN  Figure  2.17: P r o c e d u r e f o r u s i n g C o m p l e t e m o d e l l i n g  [60].  82  2.3.3.1  WEAK  POINTS  Although tested some  with  the  absorption  properties  experiments  have  the  properties, column.  which  gas  laboratory for  s t i r r e d  c e l l  a  higher  unknown  It  is  to  speed,  of  cases,  maximum the  to  is  therefore for  free  ripples  of  the  above  of  the  suffer  from  physical  gas  the  Second,  laboratory  absorbers  gas  absorption  those  the  full-scale  of  not  limited  be  If  values  absorbers  c a p a b i l i t i e s .  An  limitation is  r e s t r i c t i o n s .  of  operated  a at  area  becomes  contacting  surface.  develop with  the the  it  matched  interface  gas/liquid  of by  the  speed.  to  full-scale  known.  modelling, s t i r  been  physical  may  their  desirable  full-scale  7)  desired  gas-liquid at  the  the  the  properties  Point  ,  on  identical  to~  v  have  s t i l l  precisely  the  due  due  procedure which  its  a  of  absorption  is  ° ,  performed  some  case  L  above  they  F i r s t ,  be  values  are  in  the  k  G  be  absorbers  example  (k ,  desired  Third,  physical  absorbers,  must  to  MODELS  described  deficiencies.  column  obtain  models  plant  absorption  to  LABORATORY  two  pilot  important  OF  a  new  chemical  design reaction  83  CHAPTER  3  THEORY  This chapter presents rigorous mathematical  the t h e o r e t i c a l  f r a m e work  m o d e l l i n g and t h e proposed  t e c h n i q u e f o r s i z i n g gas a b s o r b e r s w i t h c h e m i c a l  3.1  MATHEMATICAL  Packed  Treybal  [105]  design  improved first  procedures  reaction.  on  first  recent  years.  f o r steady  state,  involving single  solute  in  a method  stripping  f o r the heats  of  a b s o r p t i o n , s o l v e n t e v a p o r a t i o n and c o n d e n s a t i o n as w e l l  as  heat and method was  The p r o c e d u r e  based  substantially  developed  a d i a b a t i c a b s o r p t i o n and systems.  pilot plant  MODEL  absorber  p r i n c i p l e s have  for  mass t r a n s f e r  properly  resistances i n  successfully tested  u s i n g the air-ammonia-water [75]  subsequently  systems. al.  accounts  extended  both phases.  The  and Khurana  [106]  by R a a l  system. the  F e i n t u c h and  work  to  Treybal  multicomponent  E x p e r i m e n t a l v e r i f i c a t i o n was p r o v i d e d by K e l l y e t  [106] f o r  the p h y s i c a l  a b s o r p t i o n of  a c i d gases  from  c o a l gas u s i n g methanol as t h e a b s o r b e n t .  R i g o r o u s t h e o r i e s f o r a b s o r p t i o n with were w e l l d o c u m e n t e d by  Astarita  The  were  previous  efforts  chemical  reaction  [17] and Danckwerts  primarily  directed  [18]. towards  84  developing  expressions  coefficients.  By  for  contrast, l i t t l e  d e v i s i n g d e s i g n methods. isothermal  gas  the  mass  emphasis  transfer  was p l a c e d  A new s e t o f d e s i g n e q u a t i o n s  absorption  r e c e n t l y developed  local  with  chemical  reaction  by J o s h i e t a l . [ 6 5 ] . H o w e v e r ,  losses are generally  suggested  for was  assuming  a d i a b a t i c c o n d i t i o n s w o u l d h a v e been more r e a l i s t i c heat  on  because  small i n i n d u s t r i a l absorbers  as  by T r e y b a l [ 1 0 4 ] a n d P a n d y a [ 5 4 ] .  A r i g o r o u s design procedure with  chemical  reaction  The  procedure  was  was b a s e d  f o r a d i a b a t i c gas a b s o r b e r s  first on  d e s c r i b e d by P a n d y a [ 5 4 ] .  Treybal's concepts  [104] f o r  a d i a b a t i c , p h y s i c a l gas a b s o r p t i o n and Danckwerts'  work [ 1 8 ]  on  reaction.  isothermal  gas  absorption  Pandya's procedure  accounted  reaction,  solvent  evaporation  reactions  in  transfer  the l i q u i d  resistances  for  and  phase  i n both  commercial  chemical  f o r t h e heats of a b s o r p t i o n and condensation,  as w e l l  as heat  phases.  [107] used a s i m i l a r procedure results  with  [108]  used  a  absorbers  in  which  carbonate  solutions.  p r e d i c t i o n s and f i e l d absorber  similar  a n d p r e s e n t e d some  processes;  carbon  approach dioxide  A l t h o u g h good d a t a was  and  DeLeye and  mass  Froment numerical  comparisons  i n d u s t r i a l d a t a were h o w e v e r n o t g i v e n . al.  chemical  with  Recently, Sanyal et to  is  model  removed  Benfield with  hot  agreement between  the  claimed, only  i n l e t and o u t l e t d a t a were p r e s e n t e d .  two s e t s  of  85  3.1.1 MODEL  The  FORMULATION  m a t h e m a t i c a l model p r e s e n t e d  h e r e i s b a s e d on t h e  a l g o r i t h m p r o p o s e d by Pandya [ 5 4 ] s i n c e i t i s r i g o r o u s b a s e d on t h e w i d e l y a c c e p t e d c o n c e p t s [104] and Danckwerts  p r o p o s e d by  and  Treybal  [ 1 8 ] . F i g u r e s 3.1 a n d 3.2 a r e s c h e m a t i c  d i a g r a m s o f an a d i a b a t i c , p a c k e d a b s o r b e r a n d a d i f f e r e n t i a l packed s e c t i o n ,  respectively.  A five-component  c o n s i d e r e d which i s comprised of an a c i d g a s ( A ) , an i n e r t in the  l i q u i d and  chemical reaction  a  liquid  an i n e r t c a r r i e r solvent  reaction product  i n t h e l i q u i d phase  A + v B kB  =  system gas  i s (I),  ( S ) , a r e a c t a n t (B) (C).  The  overall  i s g i v e n by  C  (3.1.1)  The m a j o r a s s u m p t i o n s o f t h e p r e s e n t m o d e l a r e : t h e r e a c t i o n is  f a s t and takes p l a c e only  mass t r a n s f e r liquid  resistances for the  phase a r e n e g l i g i b l e ;  same f o r h e a t negligible;  i n the liquid  and  the  mass t r a n s f e r ;  inert  film;  solvent  interfacial axial  heat  (S) i n t h e area i s the  dispersion  the absorber operates a d i a b a t i c a l l y .  and  is  A,out  Y  Y  T  86  S,out G.out  A  -B,in T  Y -HiY  s  C  T +dT  G  T  S  G  L , in  B  r  A dz  I Y  C +dC  B  T,+dT  L  B  Y  f  A,in  S,in  -B,out  G,in  T:L,out  Y  r  Figure  S  3 . 1 : Schematic diagram of a d i a b a t i c  packed  absorbers.  Y  Y  A  +  s +  dY,  dY  s  T r : + dTr  Interface  A,i 'S.i Gas Phase  R  a,A'  R  a,S  'A,i :  s,i Liquid Phase  4G  C T  F i g u r e 3.2:  T  B  + dC +dT  B  T  D i f f e r e n t i a l s e c t i o n of packed a b s o r b e r s .  88  S i n c e no r e a c t i o n o c c u r s i n t h e g a s p h a s e , t h e t r a n s f e r of b o t h s o l u t e A and vapor of s o l v e n t can  film  be w r i t t e n a s f o l l o w s :  a,A  R  a  v  d  = G,A  z  k  =  R  a,s  a  v  d  G  a  dY  :  k  G  <YA " YA, i ^ v  p  = G,s  z  =  p  (  q a G  dZ  v  =  h  G  a  v  film,  a  v  liquid  a  v  d  z  =  k  the concentration will  be n e a r l y  A f i  explained function  phase.  film  " C *) A  a  A  of the  is  at  Therefore,  is :  v  dZ  (3.1.5)  i s the e q u i l i b r i u m  o f t h e d i s s o l v e d gas A i n t h e l i q u i d  i n C h a p t e r 2, t h e enhancement f a c t o r i s a of hydrodynamic p r o p e r t i e s ,  place  dissolved  that which  of the l i q u i d  L°,A I < C  by :  f a s t and t a k i n g  where I i s t h e e n h a n c e m e n t f a c t o r a n d C concentration  i s given  (3.1.4)  mass t r a n s f e r o f A i n t h e l i q u i d  a,A  z  dZ  a s s u m e d t o be  e q u i l i b r i u m w i t h i n the bulk  R  d  gas and l i q u i d  L  only  the bulk  J  (3.1.3)  - T )  G  is  gas i n  (3.1.2)  s  Since the reaction i n the l i q u i d  z  dY *  T  (T  d  A  Ys " y s , i  The h e a t t r a n s f e r b e t w e e n  the  S w i t h i n t h e gas  reaction  bulk.  As  complex  kinetics,  and  89  concentrations  of  determined for liquid order  film.  both  the For  specific  where C  based  on  C  place  in  instantaneous is  A  must  the  second  negligible,  the t w o - f i l m  +[(C * D ) / U B  B  C  A B  theory  the  can  be  and  D  D )]}  A f i  A  i s a bulk c o n c e n t r a t i o n  B  diffusivities  respectively.  For  of  A  of  and  the case of  B  r e a c t a n t B. in  the  D  A  liquid  second-order f a s t  reactions,  f a c t o r c a l c u l a t i o n s have been e x p l a i n e d  C h a p t e r 2.  other  For  cases,  and  A s t a r i t a et a l . [19]  The  change  L dC  should  in concentration  (C) c a n  =  B  be  f  A  B  w r i t t e n as  R  3 f A  the  a  v  dZ  of  w o r k s by D a n c k w e r t s  be  B  film,  the enhancement  product  be  [54]:  = (1  are the  function  reaction taking  r e a c t i o n where  enhancement f a c t o r  I  This  example, f o r a simple  irreversible  w r i t t e n as  phases.  in [18]  consulted.  reactant  (B) and  reaction  :  •  (3.1.6)  and  L  dC  c  " a,A R  a  v  d z  (3.1.7)  90  Therefore,  the o v e r a l l m a t e r i a l balance  the d i f f e r e n t i a l Equations  dY  height  3.1.2  a n d 3.1.6:  =  (L/i> ) dC  A  A B  The o v e r a l l h e a t  G (I(Yj C T  can  P f  balance  j))  dT  be  f o r a component  obtained  by  over  rearranging  (3.1.8)  B  over  dZ c a n be w r i t t e n a s :  G  (heat change i n the gas phase) = L C dT (heat change i n t h e l i q u i d P f L  L  phase)  + Gj. H dY ( h e a t s o f a b s o r p t i o n and r e a c t i o n ) R  + G (heats of  where j d e n o t e s component  A l s o , t h e r a t e of heat  A  H dY evaporation)  x  s  (3.1.9)  s  A,S, a n d I  transfer  between t h e gas and  liquid  phases i s g i v e n by:  G  T  (Z(YjC  P f  j ) ) dT  (heat change i n t h e gas phase)  G  =  h  Q  a  v  (T  Q  - T ) L  dZ  ( h e a t t r a n s f e r between gas and l i q u i d )  (3.1.10)  91  The  interfacial  obtained  concentration  of  by c o m b i n i n g of E q u a t i o n s  YA,i  =  YA  - a,A/< R  p  k  the  solute  3.1.2  and  gas  A  is  3.1.5:  G>  (3.1.11)  where  R  a  and  =  *I  K  L ° <  H  P  YA  ~  CA*^  1  +  L  H denotes Henry's c o n s t a n t .  YA,i'  Equations  3.1.11  and  I H ( k ° A ) ]}  Since 3.1.12  (3.1.12)  G  I d e p e n d s on need  to  and  be  solved  simultaneously.  3.1.2  COMPUTATIONAL PROCEDURE  At  the  parameters  start are  compositions pressure The  -of  the  calculations,  known:  the  flow  of t h e  i n l e t gas  of the a b s o r b e r ;  concentration  specified.  of  A  the type in  the  I f the t e m p e r a t u r e and  s o l v e n t vapor i n the e x i t information to computational  and  gas  are  determine packing steps:  rates,  the  following  temperature  l i q u i d phases; the and  size  exit  of the  gas  height  by  total packing.  is  typically  the c o n c e n t r a t i o n known, t h e r e  and  of  the  is  sufficient  the  following  92  1.  Assume  the  temperature  concentration subject  ( Y  to  2.  liquid  c  of  leaving  energy  B,out  =  T  exit  L,out  These  with  values  (Good  at  lean  top are solvent.)  and composition  by u t i l i z i n g  are  i n i t i a l  the column  the entering  the absorber  vapor  of  overall  the mass  balances:  B , i n  c  ~  * I  < A,in  G  L , i n  T  +  AB  +  H  G  I  H  S  of  ( Y  A  the  l i q u i d  F  j  I  N  < S,in Y  A,out^  (3.1.13)  I  R  Y  )}  C [ G ( L T C  +  Gj  "  Y  temperature  =  solvent  gas.  values  S  temperature  /(L/i>  The  the  verification.  T Q and Y  the l i q u i d  and  the outlet  equilibrium values  Compute  and  in  later  approximation the  )  S  of  P  -  "  f  Y Y  is  j ) ) * ( T  A  F  Q  U  T  G  given  f  i  n  by:  -  T  G  f  0  u  t  )  )  S,out)V(L  C  P  f  L  ) } (3.1.14)  Now,  begin  transfer bottom  of  the step-by-step  in a differential the  column.  computation height,  dZ,  of  heat  starting  a n d mass from  the  93  3.  4.  Obtain  a l l  the  necessary  properties  of  diffusivity,  reaction  Estimate k ^ , G  both  k L 0  A  f A  physical  phases  (i.e.  rate constant  , kg^g,  and  hg,  a  v  chemical solubility,  etc.).  from data bases  or  correlations.  5.  Assume y {H  P  y  A  f  i  and  A  f  ii  then determine  and  the  absorption rate, R ,  is  a  CA,i which  enhancement  i s equal  factor,  then c a l c u l a t e d  I.  from  to The  Equation  3.1.12.  6.  Calculate and  6  Yh,i  until  f  o  the  approximately  7.  r  Equation  m  v a l u e s of  3.1.11. y  A  f  i  from  Repeat s t e p s both steps  5 are  equal.  Compute t h e f o l l o w i n g  g r a d i e n t s over  the  differential  height:  dY /dZ  =  R  dY /dZ  =  R  A  s  dT /dZ G  dT /dZ L  3 f A  a S  a /G v  :  a /Gj v  (3.1.15)  (3.1.16)  (3.1.17)  94  + G  H (dY /dZ)  T  R  A  + Gj H ( d Y / d Z ) } / { L C s  8.  s  P f L  }  (3.1.18)  S e l e c t a r e a s o n a b l y s m a l l v a l u e o f A Y , an i n c r e m e n t o f A  gas c o m p o s i t i o n , so t h a t t h e above-mentioned do n o t c h a n g e s i g n i f i c a n t l y .  The l e v e l  which the next computation w i l l  z  where  next  at  be made i s :  + AZ  (3.1.19)  =  AY /(dY /dZ) A  (3.1.20)  A  Compute t h e c o m p o s i t i o n s a n d t e m p e r a t u r e s a t Z  Y  Y  T  T  c  c  10.  of packing  Z=0 f o r t h e b o t t o m o f t h e t o w e r a n d  AZ  9.  = Z  gradients  A,next  =  Y  S,next  =  Y  G,next  =  L,next  =  T  B,next  =  C  C,next  =  C  A  +  S  +  T  A*  AZ(dY /dZ)  (3.1.22)  + AZ(dT /dZ) +  B  +  C  +  AZ(dT /dZ)  (3.1.24)  L  A  z  (»< B a, A v > R  (3.1.25)  a  A  A z  ^ a,A v) R  (3.1.26)  a  Repeat s t e p s 3 t o 9 u n t i l t h e d e s i r e d Y gas i s r e a c h e d .  (3.1.23)  G  L  :  (3.1.21)  A  s  G  n e x t  A  for the outlet  95  11.  Compare T Q a n d  Y  S  those  assumed  steps  1 to 9 u n t i l  equal.  However,  because the  values  f o r step  1.  obtained If  solution  i s in  most G  S  repeat  approximately n o t be  cases  and Y  with  needed  found  to  as suggested  be by -  [54].  t h e above  f l o w c h a r t of  10  t h e y do n o t m a t c h ,  f u r t h e r i t e r a t i o n may  Computer p r o g r a m s b a s e d on  step  t h e s e two v a l u e s a r e  i n s e n s i t i v e t o the v a l u e s of T Pandya  from  written  computational  these programs  predictive ability  i n FORTRAN  of the  comparing t h e i r r e s u l t s  procedure.  i s shown i n  computer  with the  were A  developed simplified  F i g u r e 3.3.  m o d e l s was  experimental  d a t a . The c o m p a r i s o n s a r e r e p o r t e d i n C h a p t e r  tested pilot  6.  The by  plant  96  S t a r t c a l c u l a t i o n s a t the bottom o f absorber  Assume i n t e r f a c i a l  conditions  Compute enhancement f a c t o r , I  Compute heat and mass t r a n s f e r  I No  R e c a l c u l a t e and check assumed i n t e r f a c i a l conditions  I  Assume new interfacial conditions  yes  Composition meets absorber e x i t conditions  +  No  Go to next higher s e c t i o n o f tower  yes  END  Figure  3.3:  Simplified s t e p s used  flow c h a r t of the major i n the p r e s e n t computer  calculation models.  97  3.2 PROPOSED  PILOT PLANT TECHNIQUE FOR DESIGNING  GAS ABSORBERS WITH CHEMICAL REACTION  Although  there  are  a  few  d e s i g n i n g gas absorbers w i t h suffer  from  design  this  concept,  experiments  section which  and  requires  absorption-reaction necessary  available  chemical reaction,  the d e f i c i e n c i e s  o b j e c t i v e of  procedures  described i n  i s therefore involves only  system.  In  they 2.  The  t o develop  a  new  laboratory  knowledge  particular,  of  the  i t is  t o know t h e c h e m i c a l r e a c t i o n m e c h a n i s m ,  r a t e c o n s t a n t s , mass  still  Chapter  small-scale  minimal  for  t r a n s f e r c o e f f i c i e n t s and  not  reaction  interfacial  area.  3.2.1 THE PILOT PLANT TECHNIQUE*  The  proposed  P l a n t Technique pilot  procedure,  subsequently c a l l e d  (PPT), i s based  columns and i s p r i m a r i l y  the  on m e a s u r e m e n t s p e r f o r m e d intended f o r absorber  when b a s i c d e s i g n d a t a a r e u n a v a i l a b l e . The f u n d a m e n t a l i s t o use p l a n t model  a small or  PPM  Pilot  column, subsequently column", t o  called  simulate  the  the  on  sizing idea "pilot  full-scale  * Initial work on t h e PPT h a s been p r e s e n t e d at the Symposium on S c a l e - u p of I n d u s t r i a l Chemical Processes ( T o r o n t o , 1988) a n d h a s been p u b l i s h e d i n t h e Canadian J o u r n a l of Chemical E n g i n e e r i n g , 67(4), 602-607(1989).  98  (industrial of t h e  size)  absorption  proposed  procedure  tower. is  The s c h e m a t i c  shown  in  diagram 3.4.  Figure  An  e s s e n t i a l c o n d i t i o n o f t h e PPT i s t h a t t h e m o d e l c o l u m n must have t h e  same  hydrodynamic c o n d i t i o n s  as  the  full-scale  column.  Consider  that  steady-state  conditions  prevail  i n the  p a c k e d c o l u m n a n d t h a t o n l y one c o m p o n e n t , A, i s a b s o r b e d by the  l i q u i d . The d o m i n a n t c h e m i c a l  reaction i n the l i q u i d  is  denoted by:  A  At any p o i n t  +  v B kB  =  C  i n t h e column, t h e t r a n s f e r o f A ( o r t h e change  o f B) p e r u n i t v o l u m e o f p a c k i n g  fora differential  element  dZ i s g i v e n by  Overall absorption  r a t e = (A l o s t by g a s p h a s e ) = (A g a i n e d  by l i q u i d  phase)  + (A removed by t h e r e a c t i o n ) where (A removed by t h e r e a c t i o n ) = j» g(B consumed A  by t h e r e a c t i o n )  F i g u r e 3.4  S c h e m a t i c of the P i l o t  Plant  Technique.  100  The o v e r a l l a b s o r p t i o n  R  v,A  r a t e c a n be e x p r e s s e d a s : =  f  *PA' B ' G' L ° ' v C  k  k  a  1> A B * r  and R  dZ  V f k  =  GjdY  = LdC  (3.2.1)  A  + 7r  A  (3.2.2)  dZ  A B  where r  and  v,A  =  f  * A ' B> > c  C  t h e c h a n g e o f component p  R  AB  *  s  t  n  7r  dZ = - L d C  A B  B i s given by: (3.2.3)  B  o v e r a l l absorption  e  packing, p  A B  T  A  r a t e o f A p e r u n i t volume  i sthe p a r t i a l pressure of A i n the bulk gas,  i s t h e volume o f  l i q u i d p e r u n i t volume  the  o f p h y s i c a l l y d i s s o l v e d A, a n d r  concentration  reaction  rate  between A  and  dependent of t h e r e a c t i o n and  of  of packing, C  B p e r volume o f  A  B  A  7 is  i s the  liquid  and  k i n e t i c s o f t h e r e a c t i o n between A  B i n t h e l i q u i d phase.  A material  b a l a n c e a r o u n d t h e t o p s e c t i o n o f t h e column  can  be w r i t t e n a s :  G  I  t A,out " A,z3 Y  y  = " t A , i n " A,zl L  c  c  + <L/v  where L i s t h e s u p e r f i c i a l  A B  )[C  liquid  B r i n  - C  flow  B f Z  ]  (3.2.4)  rate. I t should  be  101  noted that there height  i s o n l y one p a i r o f f l u i d c o n c e n t r a t i o n s a t  Z that s a t i s f i e s  E q u a t i o n 3.2.4 f o r a g i v e n  s e t of  top and bottom c o n d i t i o n s .  For  some  processes,  gas  treating  the l i q u i d  processes,  composition  terms of t h e l i q u i d  especially  amine  i s u s u a l l y expressed  l o a d i n g , a, which  i sdefined as  in  moles  o f s o l u b l e g a s ( p h y s i c a l l y a n d c h e m i c a l l y a b s o r b e d ) p e r mole of t o t a l  reactant  i n the l i q u i d .  (3.2.5)  where C  A  i s the t o t a l  t  concentration  of A p h y s i c a l l y and  c h e m i c a l l y absorbed i n t h e l i q u i d phase and C ^ A  concentration  of the chemical  s i n k f o r t h e component A.  l o a d i n g o f component A i n t h e l i q u i d  a  A  = A,t/ B,t C  C  =  ( C  A  h,$)/ B,t  +  denotes the  c  c  The  i s g i v e n by:  (3.2.6)  where C  (3.2.7)  A,<: = <Vi»AB>< B,t - B> C  C  Therefore, da  A  = <1/C , > B  t  (  d C  A  +  <3C ,c) A  (3.2.8)  and  dc  A f C  = -OA  A B  )dc  B  (3.2.9)  1 02  The mass b a l a n c e written  the  Y  of the  column can  be  " A,zJ Y  =  The a b o v e obtain  top part  i n terms of l o a d i n g a s :  lt A,out  G  over  L C  B,tt A in  " A,Z>  a  equations can  be  (3.2.10)  a  f  r e a r r a n g e d and  integrated  to  t h e t o t a l h e i g h t , Z , o f t h e column : t  V  z  =  t  Gj  A,i n  Jdy /[R A  v  V f A  d - y  A  )  2  (3.2.11)  ]  A,out  (from Equation  3.2.1)  or c  Z  =  t  A,out  L |dC /R A  c  c  V / A  A,in  -  L |dC /(^ B  c  (from Equations  B,out A B  R  V / A  )  (3.2.12)  B,in  3.2.1 a n d 3.2.3)  or a  z  t  =  L C  B,t  | a  A,i n d a  A/ v,A R  (3.2.13)  A,OUt  (from Equations  3.2.2, 3.2.3, 3.2.8 a n d 3.2.9)  103  In  order t o evaluate the  integral,  R  m  V f A  u  s  t  D  known  e  as a f u n c t i o n o f gas and l i q u i d c o m p o s i t i o n s . F o r any h e i g h t Z, t h e s e c o n c e n t r a t i o n s  c a n be o b t a i n e d  f r o m mass  balance  equations, provided the corresponding values at the top (or the bottom) of t h e column a r e g i v e n , as i s u s u a l l y t h e c a s e .  Although values,  there  they  are a  cannot  be  few  methods t o  applied  to  determine  the  R ,A V  systems  where  f u n d a m e n t a l d e s i g n d a t a a r e n o t known. The w e a k n e s s e s o f t h e aforementioned  u s i n g t h e PPT, t h e R can  values along the f u l l  V f A  be m e a s u r e d d i r e c t l y  have t h e  2.  methods h a v e been d e s c r i b e d i n C h a p t e r  from a model column  same h y d r o d y n a m i c  c o n d i t i o n s which  scale  column  i f both  columns  include  transfer coefficients,  i n t e r f a c i a l a r e a and l i q u i d  S i m i l a r hydrodynamics  c a n be  a c h i e v e d by  same s u p e r f i c i a l full-scale  c o l u m n must a l s o  gas and l i q u i d  column. T h i s  packing the  PPM full-  be o p e r a t e d a t  velocities  means t h a t  mass  hold-up.  c o l u m n w i t h t h e same t y p e a n d s i z e o f p a c k i n g s a s t h e s c a l e c o l u m n . The PPM  By  t h e PPM  as those of column can  the the be  much s m a l l e r t h a n t h e f u l l - s c a l e  column i n b o t h d i a m e t e r and  height as long  l i q u i d flow  as the  gas and  rate per  unit  c r o s s - s e c t i o n a l a r e a o f t h e PPM c o l u m n a r e t h e same a s t h o s e in the f u l l - s c a l e  column.  behavior of  and  similar.  gas  Therefore,  Under t h e s e c o n d i t i o n s , t h e  liquid  in  the physical  b o t h c o l u m n s s h o u l d be  identical  both  columns  gas a b s o r p t i o n  should  flow be  data  for  provided wall effects  are  104  n e g l i g i b l e . The s p e c i f i c a b s o r p t i o n r a t e p e r u n i t v o l u m e p a c k i n g , w h i c h now d e p e n d s of  o n l y on t h e b u l k  concentrations  r e a c t a n t s i n t h e g a s a n d l i q u i d p h a s e s , c a n be  f o r v a r i o u s gas and l i q u i d  l i q u i d phases a t l e v e l  Z  and temperature  v  A  Z i n the f u l l - s c a l e  ( a t Z a n d Z ) must be s i m i l a r m  s c a l e columns.  Hence R  column,  i n t h e PPM a n d f u l l -  c a n be d e t e r m i n e d  V f A  of t h e gas  i n t h e PPM c o l u m n a r e a r r a n g e d  m  t o be t h e same a s t h o s e a t l e v e l then R  measured  compositions.  Once t h e b u l k c o m p o s i t i o n s and  of  experimentally  a s a f u n c t i o n o f t h e f l u i d c o n c e n t r a t i o n s by u s i n g t h e PPM column. then  The  readily  h e i g h t of t h e f u l l - s c a l e a b s o r p t i o n tower found  by  numerical  integration  3.2.11, 3.2.12 o r 3.2.13. ( A l t e r n a t i v e l y , tower h e i g h t  i s given,  i t sabsorption  of  i f the  i s  Equations full-scale  capacity  c a n be  predicted.)  It the  i s c l e a r t h a t t h e PPT d o e s n o t r e q u i r e k n o w l e d g e  hydrodynamic  Consequently,  and  t h e weak p o i n t s  overcome ( s e e Route # 4  tower,  hydrodynamic t h e PPT  r e g a r d l e s s of  parameters.  o f t h e p r e v i o u s models a r e  i nFigure 3.5). Since  values are obtained f o r R t h e same  physico-chemical  V f A  experimental  f r o m t h e PPM c o l u m n w h i c h  characteristics  procedure  of  as  i s applicable  whether t h e o v e r a l l  rate of  the  has  full-scale  to a l l  cases  absorption  i s  105  DEFINITION OF PROCESS CONDITIONS - T o t a l f l o w r a t e s o f gas and - I n l e t and o u t l e t c o n d i t i o n s  liquid  r  SPECIFY GAS-LIQUID CONTACTING SYSTEM - Type and d e t a i l s of p a c k i n g s  r OBTAIN PHYSICAL  INFORMATION  - D e n s i t i e s and v i s c o s i t i e s - G a s - l i q u i d e q u i l i b r i u m data 1  r  DETERMINATION OF SUPERFICIAL V E L O C I T I E S Liquid side Gas s i d e OBTAIN PHYSICAL GAS ABSORPTION  PARAMETERS  - Mass t r a n s f e r c o e f f i c i e n t s - I n t e r f a c i a l area - L i q u i d hold-up OBTAIN ADDITIONAL  INFORMATION  - Diffusivities - Solubilities - Reaction k i n e t i c s  ®  DETERMINATION OF ENHANCEMENT FACTOR  DETERMINATION OF  (K a ) G  v  a v e  DETERMINATION OF ABSORPTION RATE  ± DETERMINATION OF COLUMN HEIGHT  Figure  3.5:  Main d e s i g n p r o c e d u r e s f o r g a s a b s o r b e r s with chemical r e a c t i o n  106  p r i m a r i l y determined the bulk  or i n  the r e a c t i o n  both.  a p p l i e d t o systems instantaneous to F i g u r e 2.2)  by  i n the l i q u i d  This implies  that  with a l l reaction slow  provided  ( a l s o see  that the  wall  in  may  be  t h e PPT  regimes  reaction  film,  ranging  from  S e c t i o n 2.1  and  end  and  effects  are  negligible.  The  model column  are d i f f e r e n t  (typically  s c a l e column. by proper design  may  have w a l l  end  effects  which  g r e a t e r ) than those  of the  full-  Fortunately,  t h e s e e f f e c t s may  design of the packed can  be  achieved  and  if  column. the  be  minimized  In g e n e r a l , such  following  criteria  satisfied:  1.  Good  distribution  initial in  the  and  intermediate  packed  bed.  F a i r [ 8 5 ] , t h e number  of l i q u i d  cross sectional area  of the column  least [86],  340  per  the  maintained  m^.  As was  good  liquid  fluid  According  streams  per  by  distribution  6 t o 10 c o l u m n d i a m e t e r s  at  Treybal can  by h a v i n g a r e d i s t r i b u t i o n p l a t e  the column e v e r y  unit  s h o u l d be  suggested  to  be  inside  or  every  6 t o 7 m of p a c k i n g h e i g h t .  2. L a r g e  r a t i o of column diameter  size. According to  Fair  [134], the  to  packing  r a t i o of  the  a are  107  column ID t o p a c k i n g  size  conventional packings flow  (wall  must be a t l e a s t  i n order  e f f e c t ) . However,  t o minimize this ratio  reduced t o 6 f o r high e f f i c i e n c y  random  as  For  reported  packings,  by  presented  [132].  t h e column diameter  0.03 m w i t h o u t  More d e t a i l s  Billet  wall  may  be  packings structured  may be a s s m a l l  any s i g n i f i c a n t w a l l e f f e c t s  t h e proper  on  8 for  column  design  as  [133].  criteria  i n C h a p t e r 5.  DETERMINATION  OF R  v  A  To o b t a i n t h e s p e c i f i c a b s o r p t i o n r a t e f r o m PPM t e s t s , theconcentration p r o f i l e and R R  column  i n t h e column i s measured  i s c a l c u l a t e d from t h e s l o p e o f t h e p r o f i l e s , i . e .  V f A  v,A  where  are  = I clY /dZ  (3.2.14)  G  A  t h e mole r a t i o , Y , i s g i v e n by A  Y  A  = YA /<  - A " Ys>  1  (3.2.15)  V  The s p e c i f i c a b s o r p t i o n r a t e c a n a l s o be o b t a i n e d profile  R  from t h e  of the l i q u i d composition, i . e .  V f A  = L dC /dZ A  (L/*> )dC /dZ AB  B  (3.2.16)  108  or R  V f A  = LC  da /dZ  Bft  S i n c e the R  (3.2.17)  A  values are determined  V > A  the c o n c e n t r a t i o n p r o f i l e s , the o v e r a l l  mass  there  transfer  i s no n e e d t o assume  coefficients  i m p l i e d by t h e e m p i r i c a l d e s i g n m e t h o d  The  experimental  values w i l l  from the s l o p e  procedures  of  of that  a r e constant  as  (see s e c t i o n 2.3.1).  obtaining  t h e R ,A V  be d e s c r i b e d i n S e c t i o n s 5.5 a n d 7 . 1 .  3.2.2 A SHORT-CUT PROCEDURE FOR PPT  If the concentration of degree of conversion rise  significantly  r e a c t i o n . Once temperature  are high, the l i q u i d due  t h e heats  reaction rates, s o l u b i l i t y  PPT t o n o n - i s o t h e r m a l  as  to  t h e o p e r a t i o n becomes  d e p e n d on t e m p e r a t u r e ,  well  r e a c t a n t and t h e  of  temperature  R ,A V  m a  Y  b  e  situations,  may  absorption  and  non-isothermal,  the  a l o n g t h e column changes a p p r e c i a b l y and,  the chemical  determined  the liquid  since  and d i f f u s i v i t y  a f f e c t e d . To a p p l y R ,A v a l u e s V  a l l the  h a v e t o be  as f u n c t i o n s o f gas and l i q u i d c o n c e n t r a t i o n s temperature.  The  total  c a p a c i t y ) of the column c a n s t i l l  height be f o u n d  (or  as  absorption  by u s i n g  Equation  109  3.2.11.  I t i s convenient,  assume t h a t t h e p o i n t of the  and i n  temperature of  column a r e  most c a s e s  t h e gas and  approximately  heat c a p a c i t y of t h e l i q u i d  the  valid,  to  l i q u i d at  any  same s i n c e  p h a s e i s much l a r g e r  than  the that  of t h e gas phase.  To  reduce the experimental  i s not necessary t o for  the  values  that  given  suggests  itself.  full-scale  and l i q u i d behavior  operating  to  the  The  (see Figure  sampling points)  3 . 6 ) .  the  s p e c i f i e d , c a n be (y (1,n)} A  gas  composition  obtained  starting ( C  the  B  by v a r y i n g  operation,  that of the f u l l - s c a l e  the i n l e t  column. S i n c e  g a s p h a s e i s much s m a l l e r  notionally  from  ( 1 , 1 ) }  (y (1,1)1, A  t h e gas  the  therefore  The m o d e l  column the  section i s known  which  is  composition In the  temperature of  l i q u i d o f t h e model c o l u m n i s a l s o a d j u s t e d as  is  e n t e r i n g t h e b a s e o f t h e PPM c o l u m n .  of n o n - i s o t h e r m a l  V  i s used t o s i m u l a t e  c o l u m n s e c t i o n by s e c t i o n ,  treated  R ,A  along  procedure  column  To  full-scale  conditions-, only  a t t h e t o p . The l i q u i d f e e d c o m p o s i t i o n  and  the  concentrations  full-scale  rate  compositions. in  needed; a t i m e - s a v i n g  into m sections  (equipped with n  1  s e t of  correspond  column a r e r e a l l y  divided  o f gas  absorption-reaction  column f o r a  i n t h e PPT, i t  determine the s p e c i f i c absorption  e n t i r e range  simulate  work i n h e r e n t  t o be t h e  case the same  t h e heat c a p a c i t y of  than t h a t of t h e l i q u i d ,  the  L  C  110  G  B.in |  j Vput  S  E C  T  I 0 N  (1)  A  S  s  E C T I 0 N (2)  t  E  C T  I 0 N (2)  * *  I—T C (2.n)  ,  0  (2,n|  C (m-1,1) fl  1  1 S E C T I 0 N  <m-l)  S E C T I 0 N  s  (m) C  B,out~{  E C T I 0 N (n.)  *  •  f  Y  1  A,in  C (m,n|  *  «  r(m,n-t) A  F  fl  FULL COLUMN  Figure  MODEL COLUMN  3.6 Schematic r e p r e s e n t a t i o n t o s i m u l a t e i n d u s t r i a l a b s o r b e r s u s i n g t h e PPT s h o r t - c u t p r o c e d u r e .  Ill  temperature to  o f g a s e n t e r i n g t h e m o d e l c o l u m n may be a d j u s t e d  be t h e same a s t h a t o f t h e l i q u i d . When t h e s e  a r e met,  the model  column behaves  conditions 1 of the  like section  full-scale  column; c o n s e q u e n t l y t h e o u t l e t c o n c e n t r a t i o n of  the l i q u i d  {C (1,n)}  and thetemperature  B  b o t t o m c a n be  measured.  Then,  the concentration  c a n be  measured  profiles y  B  B  y^(l,n)}  column  t o C ( l , n ) and  a l o n g t h e model column {e.g. C ( 1 , 1 ) to  a t t h e model  and R ,A V  values  A  ( l , l )  can  be  determined.  For y (2,1) A  of  section  thesection  C (2,1)  i t st o p concentrations  a r e made e q u a l t o  i s necessary of  2,  B  and  the c o n c e n t r a t i o n s a t t h e bottom  1 { C d , n ) and y ( l , n ) , r e s p e c t i v e l y } . A  B  f o r t h e temperature  I fi t  t o be m a t c h e d f o r t h e  non-isothermal o p e r a t i o n , t h e temperature  of t h e  case  liquid  e n t e r i n g t h e m o d e l c o l u m n i s a l s o s e t t o be t h e same a s t h a t of  the e x i t  stream  t h e n be u s e d section  section  t o simulate this  1. The m o d e l c o l u m n  section  can  i n t h e same way a s t h e  1.  The p r o c e d u r e of  leaving  the f u l l - s c a l e  full-scale experiments  column  i s repeated  u n t i l the bottom  column a r e reached. c a n t h u s be  R ,A V  obtained.  v a  l  the order of  m.  When  number c a n be f u r t h e r  R  V f A  reduced  along the  u e s  The  required t o simulate the f u l l - s c a l e  conditions  number  of  column i s of  does n o t change r a p i d l y , by p e r f o r m i n g e x p e r i m e n t s  this only  112  on some s e l e c t e d  sections  (e.g. section  1, 3, 5,...  or  1,  4,  8 , . . .)  3.2.3  V E R I F I C A T I O N OF  PPT  A l t h o u g h t h e PPT believed  to  have  concept developed i n  general  validity,  its  u s e f u l n e s s were t e s t e d w i t h  full-length  which  absorbed  carbon  solutions propanol  of  because  is  sodium  hydroxide  (AMP)  verification  The  dioxide  which i s  will  i t  has  been  easy  evaluation  of  principles.  By c o n t r a s t ,  because  introduced information  to  studied  relatively  chosen  it  Consequently, p r e d i c t i o n s y s t e m b a s e d on f i r s t  aqueous  early is  column  new  chosen  previously, and  based - AMP  on  performance possible.  first  system  system, having  currently  is  permits  1980's and v e r y  p r i n c i p l e s i s not  The  7.  the carbon d i o x i d e  of  by  h y d r o x i d e s y s t e m was  performances  system  towers i n  h i n d e r e d amine.  experimentally  i n the  this  air  and  2-amino-2-methyl-1-  and  is a relatively  is  feasibility  extensively  examine  absorber  to industry on  from  a sterically  - sodium  thesis  absorption  be p r e s e n t e d i n C h a p t e r  carbon d i o x i d e  this  was been  little  available. for  this  1 13  CHAPTER 4 S O L U B I L I T Y OF C Q  Very l i t t l e reported  IN 2-AMINQ-2-METHYL-1-PROPANOL SOLUTIONS*  i n f o r m a t i o n on t h e C0 -AMP s y s t e m h a s 2  i n t h e open  characteristics contained,  literature  are missing. This  i s therefore  s o l u b i l i t y data  4.1  2  on t h e C 0  BACKGROUND  and  selectivity  reported propanol,  chapter,  solubility  which  to provide  is  self  comprehensive  - AMP s y s t e m .  2  hindered  r e c e n t l y and a r e c l a i m e d terms of C 0  the  INFORMATION  Sterically  in  presented  and even  been  2  amines  have  t o e x c e l over  been  conventional  absorption capacity, degradation [71, 100]. Very l i t t l e  i n t h e open l i t e r a t u r e o r "AMP",  s t e r i c a l l y hindered  introduced amines  resistance  i n f o r m a t i o n has been  even f o r 2-amino-2-methyl-1-  w h i c h i s one o f t h e m o r e . w i d e l y amines.  The s t r u c t u r a l  formula  of  used AMP  is:  * T h i s c h a p t e r h a s been p u b l i s h e d i n t h e J o u r n a l o f C h e m i c a l and E n g i n e e r i n g D a t a , 3 6 ( 1 ) , 130-133 ( 1 9 9 1 ) .  114  H0-CH -C-NHo 9  I  CH  3  a n d Savage [ 7 1 ] r e p o r t e d t h e CO2 s o l u b i l i t y - i n  Sartori  3 M AMP s o l u t i o n s a t 40 a n d 120 ° C . provided C0 at  2  Roberts and Mather [95]  and H S s o l u b i l i t y d a t a f o r 2 M  AMP  2  40 a n d 100 ° C  a n d , more r e c e n t l y ,  have examined t h e d i s s o l u t i o n  solutions  Teng a n d M a t h e r  o f t h e same  [96]  g a s e s i n 3.43  M  AMP s o l u t i o n s a t 50 ° C .  The p r i n c i p a l s o l u b i l i t y data  o b j e c t i v e of  for C0  temperatures ranging  t h i s chapter i s to  in 2  2  f r o m 20  and 3 M  AMP  t o 80 ° C  since  acquire  solutions these  at  values  c o v e r t h e t y p i c a l o p e r a t i n g r a n g e s o f a b s o r b e r s and have n o t been  reported.  subsequently  present  interpreted  m o d e l [ 9 7 ] . The that  The  with  and a  p e r f o r m a n c e o f AMP  of monoethanolamine.  previous  modified  data  are  Kent-Eisenberg  i s a l s o compared  with  115  4.2  EXPERIMENTAL APPARATUS AND  The similar Gas  apparatus  metering  of the  streams  rotameters.  vapor  equilibrium  solution.  bath  d i s s o l u t i o n was  The  of  gas  through  2  a  [98].  (at a flow r a t e of  were  a  had  a  solution  then d i s p e r s e d  50 mL  of  aqueous  in  a  placed within  into  which  t h a t o f t h e AMP  containing  ±0.5  °C.  T h r e e AMP  C 0  2  samples  The  were t h e n t a k e n C0  2  [99]  and  2  AMP  and  loading using  IN  AMP  by K e n t and  SOLUTIONS  Eisenberg  c h o s e n b e c a u s e i t i s b a s e d on t h e f u n d a m e n t a l  D a n c k w e r t s and M c N e i l  C0  5.6.  SOLUBILITY  A model" o f t h e t y p e p r o p o s e d  AMP  were u s u a l l y r e q u i r e d t o  f o r t h e i r a m i n e c o n c e n t r a t i o n and  P R E D I C T I V E MODEL FOR  into  constant  f o l l o w e d by t a k i n g s m a l l s a m p l e s o f t h e 4 to 8 hours  by  precision  gas d i s p e r s e r  m i x t u r e was  the methods d e s c r i b e d i n s e c t i o n  was  were  were f o r m e d  a NaCl s o l u t i o n ,  controlled to  reach e q u i l i b r i u m .  4.3  N  then bubbled  vessels  solution periodically;  analyzed  and  2  i d e n t i c a l to  vessel  Both  temperature  C0  through  50 mL  pressure  under e x a m i n a t i o n . an  pure  mL/min)  f i l l e d with  t h i s study  by M u h l b a u e r and Monaghan  m i x t u r e was  500  used i n  desired concentration  of  The  approximately  water  procedures  t o those d e s c r i b e d  mixtures  vessel  and  PROCEDURE  because i t  had  theory given  [97] of good  116  performance  for  alkanolamine  solutions  The primary  predicting  chemical amines  acid  solubilities  in  [101,118].  equilibrium in  and  gas  water  of C O 2 ,  systems comprised  i s governed  by  the  following  equations:  RNH RNHCOO" H 0 2  + 3  =  RNH  +  C0  =  H  H 0  =  H  HC0 ~  =  H  2  2  4.1 a n d  amine  Equations  +  +  +  RNH +  2  4.2  HCO3"  +  HC0 ~  +  OH~  +  C 0  4.3  3  3  4.4 4.5  =  amine p r o t o n a t i o n  hydrolysis,  4.5 a r e t h e  respectively  typical  f o r aqueous systems c o n t a i n i n g C 0  S i n c e AMP h a s  4.1  2  4.2 r e p r e s e n t t h e  carbamate 4.3 t o  +  +  H 0  3  the  H  +  2  Equations  =  2  ionization  and  [100]. reactions  .  a t e r t i a r y carbon  atom a t t a c h e d t o t h e  amino g r o u p , i t s carbamate i o n i s h i g h l y u n s t a b l e a n d e a s i l y r e v e r t s t o amine a n d b i c a r b o n a t e ; t h i s was f i r s t by S a r t o r i  and Savage [ 7 1 ] . C h a k r a b o r t y  r e p o r t e d t h a t carbamate b e a r i n g - AMP  solutions  b i c a r b o n a t e and carbonate sinks f o r C 0 . 2  ions could not  discovered  et a l . [72]r e c e n t l y be d e t e c t e d  and  they  concluded  ions  a r e t h e o n l y major  in C0  that  2  the  chemical  117  The e q u i l i b r i u m reactions present  in  the  constants representing  C0 ~AMP-H 0 2  system, i n  2  i n excess, are given  is  +  4.6  K  3  =  [H ][HC0 ~]/[C0 ]  4.7  K  4  =  [H ][OH~]  4.8  K  5  =  [H ][C0 ]/[HC0 ~]  +  2  3  +  3  2  +  +  4.9  =  3  3  1  they u s u a l l y only 40 °C.  where p K  =  1  apply t o  Detailed  [RNH ] +  3  information and  2  on  temperature  lacking.  and c h a r g e b a l a n c e s must a l s o be  [AMP]  =  [RNH ]  a[AMP]  =  [C0 ]  +  [HC0 ~]  +  [C0  [H ]  =  [OH ]  +  [HC0 ]  +  2[C0  +  +  +  2  2  -  [RNH ]  4.10  +  3  3  _  3  loading  o f t h e AMP  overall  satisfied:  = 3  ] = 3  4.11 ]  where [AMP] a n d a d e n o t e t h e t o t a l AMP c o n c e n t r a t i o n C0  -logK^  infinitely  In a d d i t i o n t o t h e above e q u i l i b r i u m e q u a t i o n s , material  is  [H ][RNH ]/[RNH ]  s o l u t i o n s a t 25 a n d  still  water  =  as a f u n c t i o n of s o l u t i o n concentration  1  which  Ki  h a v e been r e p o r t e d ,  pK  important  by:  A l t h o u g h some v a l u e s o f K i ( o r p K  dilute  the  solution, respectively.  4.12  and the  118  The p h y s i c a l  C0  of  solubility  2  in  the  liquid  phase  is  g o v e r n e d by H e n r y ' s l a w :  P  where  PQO2  dioxide  a n o  C02  -  H  =  H  C02  t  C 0  2]  C02 denote the  partial  4.6  to  4.13  may  c o n c e n t r a t i o n s of seven s p e c i e s [HC0 "], 3  p  pressure of  i n t h e gas phase and H e n r y ' s c o n s t a n t ,  Equations  [C0 ],  [OH ], [ C 0 -  2  C02' C02' H  K  3'  K  4  a  n  d  5  K  a  = 3  r  e  be  (i.e.  ])  given.  The  be t a k e n  from t h e  C0  2  equilibria  the +  3  provided  p a r a m e t e r s may  representing  find +  a n d K,  since  to  2  experimentally.  [97]  carbon  [RNH ], [ H ] , [RNH ],  measured  Eisenberg  [AMP],  first The  they  were  aqueous  latter  four  K  3  =  i n t o SI u n i t s by Chakma a n d M e i s e n  exp{-241.8l8 + 298.253x10 T" 3  + 332.648X10 T 8  K  4  =  - 3  in  solutions  of  - 3  148.528x10 T~ 6  1  2  8  -  1  +  later  [118]:  - 282.394x10 °T" }  exp{39.5554 - 9 8 7 . 9 X 1 0 T " - 146.451X10 T  1  568.828x10 T 5  + 136.146X10 T" } 4  2  (4.14)  4  1 0  by  successful  c o n v e n t i o n a l a m i n e s [ 1 0 2 , 1 0 3 ] . T h e s e c o r r e l a t i o n s were converted  a,  three  correlations derived  in  1 3  respectively.  used  parameters are  Kent and  -  4  - 2  (4.15)  119  K  =  5  exp{-294.74  + 364.385x10-%  + 415.793xl0 T~ 8  H  C02  A nonlinear on  the  available Centre,  f o r the  v a l u e s c o u l d be reaction  + H 0  2  3  usually normally [H ]  [RNH ], 2  10  - 8  ,  the  and  equations  which which  1  system  2  is  Computing  had t o  These  the approximate  C0 -AMP  is  numerically.  and K  calculations.  HC0 " + RNH 3  be  initial  equilibrium  suggested  by  order of  i n the order of =  ]  t o [AMP](1 equal  2  +  3  equal  s i n k C 0 , a[AMP], i s a p p r o x i m a t e l y 3  [C0  + 3  i s approximately  and [ R N H ] .  i n the  and  +  =  2  a) a n d t h e c h e m i c a l [HC0 ~]  method  the concentrations  the  (4.17)  of B r i t i s h Columbia  solve  of  2  4  c a l l e d NDINVT,  secant  o b t a i n e d from  f r e e amine,  to  4  et al.[72]:  + RNH  2  solver  iterative  equation  Chakraborty  The  to  + 691.346x10 T~  1  9  generalized  used  (4.16)  4  + 120.037x10 T" }/7.50061  equation  estimates of  provided  C0  3  f r o m The U n i v e r s i t y was  Initial  1  2  7  B  - 354.291x10 °T~ }  exp{22.28l9 - 138.306x10 T~  =  - 155.895X10 T~  based  3  - l84.l58xlO T ^  1  were  Since the 9 to 10  - 1  11 a n d  the solution  the value 3  to  be  is  of K5 i s  ^ kmol-ions/m , the values  assigned  r e s p e c t i v e l y . The i n i t i a l  pH o f  10~  v a l u e s a r e summarized  1 0  of and  below:  120  [RNH ] = [AMP]O.0-a)  [H ] +  2  [ H C 0 ~ ] = a[AMP]  [C0 ]  3  [C0  = 3  ] = 10~  2  Kj  8  Since the values of s e v e r a l o r d e r s of To e n s u r e performed  this by  QNEWT w h i c h the K  1  The  P  [ R N H ] = a[AMP] +  3  using  H  +  4  8  t h e unknown p a r a m e t e r s r a n g e  a different  c o n v e r g e n c e may back  w i t h NDINVT,  compared  c o m p a r i s o n s were a l w a y s  PQO2  routine  method. o  r  a  v a  e x c e l l e n t and proved  taking were  u e s  with the experimental  were called  By  l  over occur.  calculations  nonlinear  on a q u a s i - N e w t o n  v a l u e s computed  = K /[H ]  10~ .  n o t happen,  i s based  [OH~]  C02/ C02  magnitude, f a l s e  does  r e c a l c u l a t e d and  10 -10  results.  that  false  convergence had not a r i s e n .  4.4  RESULTS AND  The  C0  2  DISCUSSION  solubility  summarized i n Tables the r e s u l t s , at 96].  theC0  2  data  and  t h e pK^  values  are  4.1 a n d 4.2.  To a s s e s s t h e v a l i d i t y o f  solubilities  i n 2 a n d 3 M AMP s o l u t i o n s  40 °C were c o m p a r e d  with those  reported previously [71,  A s shown by F i g u r e s 4.1 a n d 4.2, t h e a g r e e m e n t i s v e r y  good t h e r e b y v a l i d a t i n g t h e p r e s e n t  experimental  procedure.  T a b l e 4.1: E x p e r i m e n t a l Solution.  Temp. K  C0 Partial P r e s s u r e , kPa 2  Solubility  of C 0  C0 Solubility m o l C 0 / m o l AMP 2  2  i n 2 M AMP  pl^  2  293  98.93  0.960  9.343  293  49.88  0.900  9.316  293  19.28  0.880  9.704  293  8.39  0.815  9.842  293  3.23  0.781  10.242  31 3  94.00  0.940  9.339  313  47.05  0.841  9.167  313  18.01  0.768  9.373  313  7.94  0.704  9.576  313  2.70  0.620  9.864  333  82.66  0.830  8.994  333  41.14  0.735  9.015  333  16.46  0.600  9.066  333  8.00  0.476  9.059  333  1 .90  0.375  9.410  353  53.33  0.618  8.720  353  25.84  0.463  8.638  353  10.40  0.291  8.507  353  4.99  0.212  8.504  353  1 .59  0.154  8.692  T a b l e 4.2: E x p e r i m e n t a l S o l u b i l i t y Solution.  Temp. K  C0 Partial P r e s s u r e , kPa 2  of C 0  C0 Solubility . m o l C 0 / m o l AMP 2  2  i n 3 M AMP  pK  2  293 293  98.93  0.898  9.161  49.88  0.846  9.272  293  19.28  0.830  9.680  293  8.39  0.763  9.854  293  3.23  0.747  10.342  313  94.00  0.875  9. 170  313  47.05  0.815  9.267  313  18.01  0.714  9.399  313  7.94  0.643  9.589  313  2.70  0.582  9.949  333  82.66  0.809  9.116  333  41.14  0.683  9.056  333  16.46  0.546  9. 107  333  8.00  0.427  9. 104  333  1 .90  0.321  9.405  353  53.33  0.524  8.658  353  25.84  0.394  8.621  353  10.40  0.247  8.514  353  4.99  0 . 169  8.458  353  1 .59  0 . 126  8.673  }  123  F i g u r e 4.1: S o l u b i l i t y o f C 0 i n a 2 M AMP s o l u t i o n a t 40 °C. ( S o l i d c i r c l e s - p r e s e n t e x p e r i m e n t a l d a t a ; open c i r c l e s - R o b e r t s and M a t h e r [ 9 5 ] ; s o l i d l i n e s - p r e s e n t model.) 2  124  F i g u r e 4.2: S o l u b i l i t y o f C 0 i n a 3 M AMP s o l u t i o n a t 40 °C. ( S o l i d c i r c l e s - p r e s e n t e x p e r i m e n t a l d a t a ; open c i r c l e s - R o b e r t s and Mather [ 9 5 ] ; s q u a r e s - S a r t o r i and Savage [ 7 1 ] ; s o l i d l i n e s p r e s e n t model.) 2  125  v a l u e s of  The  K  r e p o r t e d here are apparent  1  c o n s t a n t s s i n c e t h e e f f e c t s of explicitly K  1  accounted  v a l u e s . The  o f T,  [C0 ]  f o r i n the  latter  and  2  system  n o n i d e a l i t i e s were  were t h e r e f o r e e x p r e s s e d a s a  [AMP].  by  Using [C0 ]  c o r r e l a t i o n was  pR}  =  and  +  found  2  a n o  -  H  The  C02  a s  following  +  1/T  2  0.038508 [AMP]  (4.18)  between t h e pK  those reported e a r l i e r .  Savage [71]  t h e y a r e somewhat  70850. [C0 ]  p r o v i d e s a comparison  p r e d i c t e d by E q u a t i o n 4.18 and  -  - 6.3899  0.095221 l n [ C 0 ]  i n t h i s work a n d  by S a r t o r i  [118].  0.49828 T  - 388.03 l n T  T a b l e 4.3  PQO2  since  f o u n d t o be o p t i m a l :  2309.1  -  Meisen  from  the  function  i s preferable to a  2  Chakma  not  model, but lumped i n t o  t h e f o r m e r c a n be c a l c u l a t e d d i r e c t l y suggested  equilibrium  values  1  The  results  agree w e l l w i t h the data r e p o r t e d and Teng a n d  h i g h e r than those  Mather  [96],  but  of C h a k r a b o r t y e t  al.  [72].  When E q u a t i o n 4.18 4.6  t o 4.13  all  species for a  result,  may  i s used  to find K ,  then  1  Equations  be e v a l u a t e d t o o b t a i n t h e c o n c e n t r a t i o n s o f g i v e n s e t of  the t o t a l C0  2  solubility,  T,  [C0 ] 2  a, may  and be  [AMP].  determined.  As  a  126  Table  4.3:  Comparison of present pKi values.  Source  Sartori  Temp. (°C)  and Savage [71]  Chakraborty T h i s work  e t a l . [72] ( E q . 4.18)  Teng and Mather T h i s work  [96]  ( E q . 4.18)  and p r e v i o u s l y r e p o r t e d  AMP Cone. (M)  CO2 P a r t i a l P r e s . , (kPa)  pR-|  40  3  0.7-305  9.70  40  1-3  0. -100  8.50  40  3  10.0  9.67  50  3.43  4-5650  9.11  50  3.43  100  9.16  127 The  QNEWT r o u t i n e  was  initial  estimates  1.0  CC^/mol AMP.  mol  4.4,  good  of  employed a  can  a g r e e m e n t was  the present the  falling  As  measured r e s u l t s ; the  of C 0  be  C0  in  2  solubilities  2  shown i n F i g u r e solubilities  s o l u t i o n s a t 40 cross-over  4.5.  i n AMP  AMP  solution  the  regenerative  a t low  r a t e s are system AMP  will  4.1  to  °C.  was  6.0  for  be  noted  that  fairly  weak  and  but  MEA  of  C0  a  is  2  solutions  than those i n  MEA  is  research  MEA  large  t r u e and  and  discussed  operate  However,  mass  transfer  the  C0 MEA _  2  therefore warranted  mass t r a n s f e r  plant absorption  for  regenerators  a i s low. and  data  r a t e s and  on  stability.  o f t h e s e two  i n Chapter  a  solubility,  solutions  system than is  are the  since absorbers  reaction  2  i t becomes  note t h a t  opposite  s u p e r i o r to  %  °C.  From t h e p o i n t o f  t h e C0 -AMP  c o m p a r e d and  and  °C,  t o 80  higher  the  that the  Further  predicted  is a  40  t e m p e r a t u r e s where  reaction kinetics,  a l s o be  °C  where  lower f o r  Some o f t h e p i l o t  Figures  i s i n t e r e s t i n g to  separation  indications  [103].  M AMP  therefore  temperatures  are  i n 2.5  A t 80  operate at elevated there  60  s o l u t i o n s are  i s seen a t 60  s o l u t i o n s are  to  I t should  range of  It  °C.  AMP  0.5  between the  results.  the  of  mean s q u a r e d e v i a t i o n  f u n c t i o n i n the  The  range  seen from  f u n c t i o n o f t e m p e r a t u r e b e t w e e n 20 and a strong  purpose with  i n t o the  found  experimental  solubility  for this  7.  systems  128  P-.  -  o 6 I l l l 11 5*10 10°  1  1  I  _1  I  I  I  l 11  '  '  •  •  i  i i  11  id 10* Partial Pressure (kPa) 1  C0  2  F i g u r e 4.3: S o l u b i l i t y o f C 0 i n a 2 M AMP s o l u t i o n a t v a r i o u s t e m p e r a t u r e s . (Open c i r c l e s - 20 °C; s o l i d c i r c l e s - 40 °C; s q u a r e s - 60 °C; t r i a n g l e s - 80 °C; s o l i d l i n e s - p r e s e n t m o d e l . ) 2  129  F i g u r e 4.4: S o l u b i l i t y o f C 0 i n a 3 M AMP s o l u t i o n a t v a r i o u s t e m p e r a t u r e s . (Open c i r c l e s - 20 °C; s o l i d c i r c l e s - 40 °C; s q u a r e s - 60 °C; t r i a n g l e s - 80 °C; s o l i d l i n e s - p r e s e n t m o d e l . ) 2  130  5*io io°  io  _1  1  io  2  C0 Partial Pressure (kPa) 2  Figure  4.5: S o l u b i l i t y o f C 0 i n 2.5 M AMP a n d MEA s o l u t i o n s at v a r i o u s t e m p e r a t u r e s . ( D o t t e d , dashed and c h a i n d o t t e d l i n e s a r e t h e model p r e d i c t i o n s f o r t h e C0 -AMP s y s t e m a t 4 0 , 60 a n d 80 °C, r e s p e c t i v e l y . S o l i d l i n e s a r e from t h e KentE i s e n b e r g m o d e l [ 9 7 ] f o r t h e C0 -MEA s y s t e m . ) 2  2  2  131  CHAPTER 5 PILOT PLANT AND EXPERIMENTAL PROCEDURE  The  p i l o t p l a n t shown i n F i g u r e  the present  absorption  which the p i l o t the Chemical  5.1  Engineering  Department,  UBC.  in  l a b o r a t o r y of The  equipment  i n the following sections.  was made o f a c r y l i c p l a s t i c  of  Calgary,  s i n c e they  Saddles  Alberta).  c o u l d be  column (7.2 m  h i g h , 0.1  a n d was p a c k e d w i t h 12.7  (provided  by K o c h  These d i m e n s i o n s  r e a d i l y accommodated  l a b o r a t o r y and p r o v i d e d 5.3  into the e x i s t i n g  f u l l - l e n g t h absorption  (1/2") ceramic B e r l Co.  5.2 shows t h e way  THE FULL-LENGTH ABSORPTION COLUMN  The ID)  studies. Figure  plant f i t t e d  d e t a i l s are described  5.1 was u s e d t o p e r f o r m  realistic  mm  Engineering  were  selected  i n the  experimental  m  existing  data.  Figure  shows t h e d e t a i l e d d i m e n s i o n s o f t h e a b s o r b e r .  The (each  f u l l - l e n g t h column  1.2  sections.  m  high)  The  redistributors  drawings are  respectively. Figure joined  together.  with  was c o m p r i s e d redistributors of  shown 5.6 a l s o  the  of s i x  sections  inserted  between  column  i n Figures shows how  section 5.4  and  two s e c t i o n s  and 5.5, are  Condenter  Regeneration  Column  Abjorpllon Column  Figure 5 . 1 :  Schematic of  the  pilot  plant Storage Tink  F i g u r e 5.2:  Picture fitted  s h o w i n g how  the p i l o t  plant  i n t o the Chemical Engineering  equipment Building  Cis  Sample Point  Liquid Simple  Point  Thermocouple  Figure the  5.3:  Schematic  absorption  column  136  Figure  5.5:  Schematic  of  the  redistributors  137  Figure  5.6:  Drawing of  the  joint  between  two  sections  138  The  dimensions  c a r e f u l l y checked  selected  for  this  absorber  were  by comparing them w i t h t h e "proper" d e s i g n  c r i t e r i a suggested p r e v i o u s l y . The comparisons  a r e shown i n  T a b l e 5.1.  To pack  a  column  p a c k i n g elements  s e c t i o n , approximately  were dumped  p l a n e d . ( T h i s way  into  t h e empty  500  mL o f -  section  of p a c k i n g i s commonly used i n i n d u s t r y  [38, 137].) The p r o c e s s was r e p e a t e d u n t i l a p a c k i n g of a p p r o x i m a t e l y  In o r d e r  and  height  1.1 m was reached.  t o vary  the e f f e c t i v e packing  height  over  which a b s o r p t i o n o c c u r r e d i n t h e f u l l - l e n g t h column, t h e gas c o u l d be i n t r o d u c e d a t d i f f e r e n t p o s i t i o n s between  sections  as shown i n F i g u r e 5.7.  The gas and l i q u i d  phases c o u l d  s e c t i o n i n l e t and o u t l e t t o determine measure t h e column type,  Omega  temperature  Engineering)  was  r e d i s t r i b u t o r of each s e c t i o n . system  i s shown  c o n s i s t e d of  i n Figure mm  a thermocouple  inserted The diagram  l o n g , 18-gauge  each  t h e i r composition.  profile,  5.8. The  at  just  the  sampling  f l u i d sampling needles  (J  below  of t h e  To  probes  fitted  with  s p e c i a l l y made 9 mm O.D. and 9 mm h i g h T e f l o n cups a t  their  tips.  100  be sampled  To sample t h e gas phase, t h e cups were p o s i t i o n e d i n  such a way t h a t t h e i r open ends f a c e d i n t o t h e d i r e c t i o n  of  139  the  gas  flow.  infrared was  gas  The  needle  a n a l y z e r by  controlled  outlets  nylon  tubes.  by  polycarbonate  For  liquid  sampling,  pointed  into  the  needles  were c o n n e c t e d  B.C.).  both of  cups can  the  be  sampling  direction t o 50  changed a l o n g system  were c o n n e c t e d  clamps the  of t h e mL  The  open  gas  sampling  (Canlab,  flow  s y r i n g e s . The  rate  the and  positions  t h e column r a d i u s . A  i s shown i n F i g u r e 5.7  .  an  Vancouver,  ends o f  liquid  to  cups the of  picture  140  Table  5.1: "Proper"  Design  C r i t e r i a of Packed Columns.  Criterion  Present  Column I D ^ 0.10 m ( F a i r [ 1 3 4 ] , Rase [ 3 3 ] )  0.10m  P a c k i n g s i z e £ 12.7 mm ( F a i r [ 1 3 4 ] , Rase [ 3 3 ] )  12.7  Column ID t o p a c k i n g s i z e ratio £ 6 to 8 ( B i l l e t et a l . [132], F a i r Liquid distribution: No. o f s t r e a m > 340 p e r m (Fair [85])  column  2  Redistribution: e v e r y 6 t o 10 c o l u m n I D ' s or 6 t o 7 m (Treybal [86])  [134])  mm  8  2546 p e r  every  1.10  m  2  m  9.53  100 mm  F i g u r e 5.8:  mm,  long,  NPT  18 gauge SS  needle  Schematic of the s a m p l i n g  system  to  143  5.2 P I L O T PLANT MODEL (PPM) COLUMN  F o r t h e sake  of convenience,  f u l l - l e n g t h absorber 5 . 3 ) . The d r a w i n g order t o  was u s e d a s t h e PPM c o l u m n  of t h i s s e c t i o n  evaluate  t h e R ,A  i s needed  3 . 2 . 1 7 ) . The l i q u i d c o m p o s i t i o n s instruments  such  as  pH  (see Figure  i s shown i n F i g u r e 5.9. I n  values,  V  concentration profile  line  the t o p s e c t i o n of the  t h e gas  (see Equations  or  liquid  3.2.14  may be m e a s u r e d u s i n g meters  or  ionic  to on-  specific  e l e c t r o d e s . However, t h e y a r e n o t v e r y r e l i a b l e u n l e s s  they  are p r o p e r l y c a l i b r a t e d .  I n t h e p r e s e n t s t u d y , i t was d e c i d e d t o m e a s u r e t h e CO2 concentration  profile  s p e c t r o s c o p y , which  i n the  i sreliable,  gas  phase  using  infrared  r e a d i l y a v a i l a b l e and  easy  t o u s e . The d e t a i l s o f t h e g a s c o m p o s i t i o n a n a l y z e r w i l l given  i n S e c t i o n 5.6.  way t h a t t h e g a s the s e c t i o n .  p h a s e c o u l d be s a m p l e d  T h i s was  sampling probes  The PPM c o l u m n was d e s i g n e d  achieved  The p i c t u r e s  F i g u r e s 5.11 a n d 5.12.  of  gas sampling probes  t h e PPM  along  placing  w i t h i n t h e packing along the column.  5.10 shows t h e p o s i t i o n o f t h e the column.  i n such a  e v e r y 0.1 m  by c a r e f u l l y  be  gas  Figure inside  c o l u m n i s shown  in  H  1  1 0 0 mm  Figure  5.9:  Drawing  of  the  PPM  column  145  F i g u r e 5.10:  Diagram showing t h e gas s a m p l i n g  position  F i g u r e 5.11: P i c t u r e o f t h e PPM c o l u m n  Figure  5.12:  Picture  of  sampling probes  along  the  PPM column  148  5.3 REGENERATION  In  COLUMN  the case of  was r e g e n e r a t e d regenerator  amine s o l u t i o n s ,  i n a separate  i s shown  the C 0 - r i c h  solution  2  unit.  The d i a g r a m  i n F i g u r e 5.13.  The  of t h e  column  had  d i a m e t e r o f 0.1 m I D , was made o f QVF g l a s s a n d p a c k e d 12.7  mm c e r a m i c  Raschig rings  r e b o i l e r was made f r o m  to a  a stainless  0.7 m h i g h ) . A s t e a m c o i l  height of s t e e l drum  1.4 m.  h e a t i n g a r e a was u s e d a s t h e h e a t i n g e l e m e n t . The at  the regenerator  j a c k e t . A water also  fitted  i s about  regenerator.  cooling coil  a stainless  1.93  s t e e l double  ( 9 . 5 3 mm OD x  The  6m  x m  2  condenser  long)  i n s i d e t h e c o n d e n s e r . The t o t a l c o o l i n g  0.325  Figures  t o p was  with  ( 0 . 7 m ID  (15.88 mm OD x 12 m) w i t h  a  tube was  surface  m. 2  5.14  to  5.16  show  the  pictures  of  the  Figure  5.14:  P i c t u r e of  the  regenerator  Figure  5.15:  P i c t u r e of t h e  top part  of  the  regenerator  Figure  5.16:  P i c t u r e of t h e  bottom p a r t  of  the  regenerator  153  5.4 A U X I L I A R Y EQUIPMENT  This section describes  the detailed  the a u x i l i a r y equipment used  specifications  i n the absorption studies  of  (also  see F i g u r e 5 . 1 ) .  The  liquid  feed and  gallon polyethylene about  0.2  least  90 m i n u t e s .  The fluid  m. 3  and  storage tanks  d r u m s . The  permitted experimental  t e m p e r a t u r e s . I t was made  s t e e l drum e q u i p p e d w i t h a  stirrer used  c a p a c i t y of  constant temperature bath  360, Chromalox  Canada).  controlled  the heating (within  ±1  made o f  each tank  45 was  runs l a s t i n g  was u s e d t o c o n t r o l of a  45 g a l l o n  at  the  stainless  6 kW i m m e r s i o n h e a t e r ( M o d e l Water,  i n o r d e r t o keep  as  were  w h i c h was  agitated  by  the bath temperature uniform, medium.  The  °C)  a  by  bath  a  was  temperature  proportional  MT  was  controller  ( M o d e l 4 9 , Omega E n g i n e e r i n g I n c . , S t a m f o r d , C T ) .  A magnetic  d r i v e pump made o f p o l y p r o p y l e n e a n d p o w e r e d  by a 1/3  Hp m o t o r  (Fabco, Model MDR-60t-t03)  feed the  solution  to  pressure  and  flow  t h e column.  rate  were  respectively. A stainless steel Co.,  M o d e l 211-513) was u s e d  190  The kPa  was u s e d  maximum and  t o pump t h e C 0  2  operating  3.8  g e a r pump ( A r c o rich  to  m /hr, 3  Instrument solution  154  back t o the  feed tank  o p e r a t i n g pressure and  or to the  r e g e n e r a t o r . I t s maximum  flow rate were  1374.0 kPa and  0.34  m /hr, r e s p e c t i v e l y . 3  A calibrated  rotameter  (Model FL-73C) was used  from  Omega  Engineering  Inc.  t o measure the a i r flow rate.- I t s  o p e r a t i n g range was 0 to 255 (std) L/min. Since the p h y s i c a l properties  of  s o l v e n t type,  solutions the  E n g i n e e r i n g Inc.)  liquid  change  rotameter  was c a l i b r a t e d  p r e c i s i o n measuring  c y l i n d e r and  measurable flow r a t e of the L/min. The  rotameter  liquid  concentration  (Model  FL-73M,  and Omega  before each  run u s i n g  stop watch.  The  rotameter  f o r measuring  o b t a i n e d from Brooks Instrument, 8M-25-2[tube] and  with  C0  2  maximum  was about  flow  rates  Markham, O n t a r i o (Model  8-RV-8[float]).  flow r a t e i s about 91 (std) L/min.  I t s maximum  a  4.0 was R-  measurable  155  5.5 PROCEDURE FOR ABSORPTION EXPERIMENTS USING THE FULL-LENGTH AND PPM COLUMNS  The desired  feed s o l u t i o n s  were p r e p a r e d  compositions.  (The  s o l u t i o n s were d e t e r m i n e d 5.6.)  A l l solution  exact  in  advance w i t h  compositions  by m e t h o d s  c h e m i c a l s were  of  described i n of  the the  Section  commercial  grade  p r o v i d e d by Van W a t e r a n d R o g e r s C o . , V a n c o u v e r , BC.  For t h e f u l l - l e n g t h column e x p e r i m e n t s ,  the l i q u i d , a i r  and  CO2 f l o w r a t e s were' measured- by t h e r o t a m e t e r s . The a i r  and  CO2 were t h e n p r e m i x e d  All  f l u i d s were p r e h e a t e d  A f t e r t h e flow r a t e and set t o the  and f l o w e d  i n t h e same g a s  line.  i n the constant temperature  bath.  c o n c e n t r a t i o n of t h e feed gas  d e s i r e d values, the  g a s m i x t u r e was  were  introduced  i n t o t h e column and f l o w e d upwards and c o u n t e r - c u r r e n t l y the l i q u i d tower. CO2  s o l u t i o n which  The e x i t  was i n t r o d u c e d i n t o t h e t o p o f t h e  gas l e f t a t t h e  t o p of t h e absorber.  r i c h s o l u t i o n leaving the absorber  in the storage  Steady  to  b o t t o m was  The  collected  tanks.  state  was  usually  reached  within  15  to  20  m i n u t e s f o r t h e PPM c o l u m n r u n s a n d 30 t o 40 m i n u t e s f o r t h e f u l l - l e n g t h column constant temperature  runs.  Steady  s t a t e was  indicated  r e a d i n g s a l o n g t h e column and  concentration of the e x i t gas.  After  by  constant  reaching steady  state,  156  the gas  c o n c e n t r a t i o n and  temperature  profiles  along  c o l u m n were m e a s u r e d a n d r e c o r d e d . The g a s s a m p l i n g a b o u t 20 mL/min. A p p r o x i m a t e l y a l s o withdrawn  a t each  sampling  using the sampling s y r i n g e . s a m p l e s were d e t e r m i n e d  fed  redistribution  p l a t e of  procedure  then  was  sample  location during  upon c o m p l e t i o n  For experimental runs m i x t u r e was  mL o f l i q u i d  rate  run  liquid  o f a r u n and  using  section.  conducted into the  the top  t h e same  was were  the  The c o m p o s i t i o n s o f t h e  methods d e s c r i b e d i n t h e next  t h e gas  40  the  as  with  t h e PPM  column j u s t  s e c t i o n . The that of  column,  below  the  experimental  the  full-length  column.  The  systems  and  operating conditions  s t u d i e s a r e s u m m a r i z e d i n T a b l e s 5.2 a n d 5.3  used  in  these  157  Table  5.2 : S y s t e m s s t u d i e d a n d number of  System  C0 -NaOH 2  Absorbent Cone. (kmol/m3)  1.2  No. o f Runs Full-length Column 6  Purpose  17  up t o 3.8  10  -  C0 -NaOH  up t o 2.5  6  24  8  24  2  C0 -AMP 2  2.0  no. o f r u n s  30  +  Comments  PPM Column  C0 -MEA 2  experimental runs.  65  to v e r i f y PPT a n d to t e s t theoretical model  well known system  to t e s t moderately theoretical well model known system to v e r i f y PPT a n d to t e s t theoretical model . to verify PPT  = 95  (total)  well known system  new system  T a b l e 5.3: O p e r a t i n g  Conditions  Gas f l o w r a t e C0 concentration  11.1 t o 14.8 mol/m-* h r up t o 20 %  L i q u i d flow rate T o t a l absorbent concentration  9.5 t o 13.5 m /m h r 1.2 t o 3.8 k m o l / m  Column t e m p e r a t u r e Column p r e s s u r e  14 t o 57 °C 101 kPa  Flooding condition  30 t o 70 %  Packing  3.25 t o 6.55 m  2  height  3  2  3  159  5.6  A N A L Y S I S OF  The by an  c o n c e n t r a t i o n of C 0  i n f r a r e d gas  Systems, 20.0  SAMPLES  2  a n a l y z e r (Model  Hamilton, Ontario).  % of C0  by v o l u m e .  2  c a l i b r a t e d with  i n t h e gas p h a s e was  The  Matheson,  a n a l y z e r was  within  r e a d i n g range  to  Before each run, the a n a l y z e r  was  m i x t u r e s of  Vancouver,  ±2  Analytical 0.0  s t a n d a r d gas  p r o v i d e d by  300D, Nova  measured  % of  C0  BC. The  2  was  in  nitrogen  a c c u r a c y of  the f u l l  scale reading.  i n t e r f e r e n c e o f w a t e r v a p o r on t h e m e a s u r e m e n t s was  In  compositions.  The  total  h y d r o x i d e ) was  found  alkali  by t i t r a t i o n  s o l u t i o n s u s i n g m e t h y l orange the  hydroxide  content,  with  s t a n d a r d 1.0  carbonate  their  (carbonate  a s t h e i n d i c a t o r ; - To  the  method  used t o determine content  No  found.  t h e c a s e o f t h e NaOH s o l u t i o n s , t h e s t a n d a r d  d e s c r i b e d by B a s s e t e t a l . [ 7 3 ] was  the  ions  and N  HCl  determine  were  first  p r e c i p i t a t e d by a d d i n g e x c e s s b a r i u m c h l o r i d e s o l u t i o n . solution  was  then  titrated  p h e n o l p h t h a l e i n as the i n d i c a t o r . the  sodium  was  t h e n o b t a i n e d by  In  hydroxide content;  the case  c o n c e n t r a t i o n was HCl s o l u t i o n s  to  with  1  The  latter  the sodium  N  HCl  The using  titration  carbonate  gave  content  difference.  of the  amine s o l u t i o n s ,  d e t e r m i n e d by t i t r a t i o n the  methyl orange  end  the t o t a l  amine  with standard 1 point.  The  N C0  2  160  content  i n the  method g i v e n  liquid by  C h e m i s t s (AOAC)  s a m p l e was  the  Association  [115].  The  precisely  measured q u a n t i t y  2 N  solution.  HCl  collected the  C0  2  C0  in a precision  gas  a p p a r a t u s and  the  in  the  are  the gas  2  solution.  found i n Appendix  A.  of  the  the  Official  involved s a m p l e by was  The  given  liquid  standard Analytical  acidifying adding  released  b u r e t t e and  procedure are  Sample c a l c u l a t i o n s  of  latter of  The  loading  d e t e r m i n e d by  details  excess  and  used to  a  then  calculate of  i n Appendix  composition  the  gas  A.  analyses  161  COLUMN  5.7  TESTING  According  to  considerations  In  order  research  in  mass  2)  Pressure  drop  3)  Mass  to  ensure  drop  tower  of  gas  flow  liquid  inoperable.  To each  drop  given  the  gas  is  and  the  was  are  is  a  the  gas  given  type  rate  in  at  in  this  size  the  point  can  be  with  difference  The  packing  and  exhibits  an  velocity,  column found  occurs.  become from  the  relationship  velocity a  of  flooding the  and  6.  flooding  and  rate  section.  flow  which  this  flooding  Chapter  and  in  afore-mentioned of  descend  flow  used  the  l i q u i d  beyond  flooding  equipped  pressure  reported  provided  flow  flooding  column  results  descending  to  the  packed  The  increased  ceases  determine  section  measure  a  The  major  columns:  i n s t a l l e d ,  applied.  containing  limit  pressure  properly  evaluation  with  three  point  the  measurements  upper  the  that  were  fed  the  flood  are  transfer  was  being  If  packed  or  transfer  A  testing  Capacity  considerations  there  [95],  1)  work  pressure  Fair  of  water-filled between  the  absorber,  manometer the  inlet  to and  162  o u t l e t . W a t e r and a i r were u s e d a s t h e l i q u i d a n d g a s p h a s e , r e s p e c t i v e l y . The w a t e r f l o w r a t e was s e t t o a v a l u e and rate.  t h e gas  The p r e s s u r e  after  steady  minutes a f t e r  state  was t h e n drop  adjusted to  predetermined  the desired  o f e a c h s e c t i o n was t h e n  was  reached  (approximately  flow  measured 10  to  t h e g a s f l o w r a t e was s e t ) . The p r e s s u r e  drops  w e r e f o u n d t o be v i r t u a l l y  t h e same f o r e a c h s e c t i o n  i n d i c a t i n g uniform  l i q u i d and g a s f l o w r a t e s .  packing,  15  which  The a v e r a g e p r e s s u r e d r o p s f r o m 6 s e c t i o n s were p l o t t e d a g a i n s t t h e gas  and l i q u i d  flow r a t e s as  shown  in  Figure  5.17. To d e t e r m i n e t h e g a s v e l o c i t y a t f l o o d i n g f o r a liquid  flow r a t e , the c r i t e r i o n  suggested  by F a i r  u s e d , i . e . f l o o d i n g o c c u r r e d when t h e p r e s s u r e 2.04 shown  kPa/m o f i n Table  packing  (2.5" of  [95]  drop  was  reached  w a t e r / f t ) . The r e s u l t s  are  5.4  To p r e d i c t p r e s s u r e c o r r e l a t i o n of  given  d r o p and f l o o d i n g , t h e  F i g u r e 5.18  suggested  u s e d . The a b s c i s s a i s t h e d i m e n s i o n l e s s  by  generalized  Treybal  [86]  was  flow parameter,  FP,  d e f i n e d as  FP = ( L ' / G ' ) / ( p / p ) 0  G  5  L  w h e r e L' a n d G' a r e t h e s u p e r f i c i a l mass f l o w r a t e s .  The o r d i n a t e i s t h e c a p a c i t y p a r a m e t e r :  (5.1)  163  CP  To  = (G' C M °- J)/(p ' L"' G gc 2  use F i g u r e 5.18,  from E q u a t i o n s from the  5.1  (  L  ?  0  )  )  ( 5  G  the v a l u e s and  5.2  o f FP and CP a r e  and  the pressure  -  2 )  calculated  drop i s  read  graph.  In order C f , must  1  f  be  t o use  t h i s c o r r e l a t i o n , the packing  supplied.  investigators  have  r e p o r t e d wide d i s c r e p a n c i e s i n Cf v a l u e s . Lobo e t a l .  [92],  C l a y e t a l . [ 9 3 ] , and 12.7  mm  (1/2")  Unfortunately,  factor,  E c k e r t [ 9 4 ] r e p o r t e d t h e Cf v a l u e s  Berl  Saddles  r e s p e c t i v e l y . T h i s d i s c r e p a n c y was  as  450,  380  and  a l s o m e n t i o n e d by  240, Treybal  [86], According t o the experimental r e s u l t s obtained i n present for  s t u d y , a Cf v a l u e  flooding  (see Table  o f 380  5.4).  gave t h e b e s t  When t h i s number was  5.19.  the  predictions used  c a l c u l a t e t h e p r e s s u r e d r o p s , a c c u r a t e p r e d i c t i o n s were o b t a i n e d a s shown i n F i g u r e  of  to also  164  Figure  5.17: P r e s s u r e d r o p s a s f u n c t i o n s o f g a s a n d l i q u i d flow r a t e . ( L i q u i d flow r a t e (kg/m s ) : s o l i d s q u a r e s - 2 . 8 0 2 ; open s q u a r e s - 4.160; open c i r c l e s - 6.740; s o l i d c i r c l e s - 8.112) 2  165  T a b l e 5.4: Gas a n d l i q u i d  flow  rates at flooding  Experimental L. f l o w r a t e kg/m2 s  Experimental Gas f l o w r a t e kg/m2 s  2.808  1.02  1.35  1.08  4.160  0.89  1.16  0.93  6.740  0.75  0.98  0.79  8.112  0.64  0.86  0.67  Predicted Gas f l o w r a t e kg/m2 s (Cf=240)  point  Predicted Gas f l o w r a t e kg/m2 s (Cf=380)  166  G' L' Cf ML PG p g J L  c  = = = = =  g a s mass v e l o c i t y , kg/m .s l i q u i d mass v e l o c i t y , kg/m .s packing factor l i q u i d v i s c o s i t y , mPa ( c e n t i p o i s e s ) 9 d e n s i t y , kg/m = L i q u i d d e n s i t y , kg/m = 1.0 =1.0 2  a s  3  3  F i g u r e 5.18: G e n e r a l i z e d c o r r e l a t i o n f o r p r e s s u r e d r o p a n d f l o o d i n g c a l c u l a t i o n s s u g g e s t e d by T r e y b a l [86].  F i g u r e 5.19:  Measured and p r e d i c t e d p r e s s u r e  drops.  168  CHAPTER RESULTS FULL-LENGTH  The  AND  DISCUSSION:  COMPARISON  ABSORBER  PERFORMANCE  AND  primary  objective  comprehensive  experimental  concentrations  and  for  C0  2  absorption  monoethanolamine no  theoretical  l i t e r a t u r e . therefore results  with  described NaOH  and  in  possible  reported.  Section  systems  Rigorous since  As  provide  gas  and  liquid  along  the  column)  have  hydroxide  the  could data  be are  modelling  insufficient  of  in  reported of  of  this  time,  modelled  the  CO2  -  fundamental  open  chapter  is  experimental  only  exactly  available  2,  results  mathematical  present  and  Chapter  in  these  the  the  (NaOH)  experimental  been  from  is  mentioned  comparisons  At  to  (i.e.  objective  3.1.  chapter  between  predictions  fundamental  l i t e r a t u r e . not  second  PREDICTIONS  sodium  solutions.  BETWEEN  THEORETICAL  p r o f i l e s  aqueous  provide  CO2-MEA  necessary  into  predictions  the  this  data  comparisons  The to  of  temperature  (MEA)  comprehensive  and  6  in AMP data  model  the since  the system have  CO2  -  the open was been  169  6.1  FULL-LENGTH ABSORBER PERFORMANCE  To e m p h a s i z e column  performance  profiles, a Taylor  with  concentration  full-length  and  temperature  statement i n t h e paper by K r i s h n a m u r t h y a n d  [140],  experimental stage  t h e importance of d e t a i l e d  asking  data  f o r comprehensive  i n order  to verify  model, i s quoted a s f o l l o w s :  and  detailed  their  nonequilibrium  " ....For  this (testing the  model), we need data, preferably taken on industrial scale columns. Composition desirable.  and temperature profiles (along the tower) are highly  Details of the equipment used are also necessary  authors would greatly appreciate correspondence readers who have information of this kind  In t h e present experimental include  378 m e a s u r e d  data  studies, the results  points:  The c o l u m n was  velocities  which  o p e r a t i o n s . The f o l l o w i n g  l i q u i d flow  concentration  131 p o i n t s  operated  i s typical  a t 30  2  C0  2  points  t o 75 %  f o r gas  absorber  conditions 3  13.5 m /m h; f e e d 3  11.5 t o 19.8 %; t o t a l a b s o r b e n t 3  22  r a t e 11.1 t o 14.8 m o l / m s ;  r a t e 9.5 t o  1.2 t o 3.8 k m o l / m ; C 0 l o a d i n g  of  131  ranges o f o p e r a t i n g  were u s e d : s u p e r f i c i a l g a s f l o w  from  6.1 a n d 6.2. They -  116 p o i n t s o f l i q u i d c o m p o s i t i o n ;  of t e m p e r a t u r e .  superficial  with any of our  "'  runs a r e summarized i n Tables  concentration;  flooding  absorption  The  2  C0  2  concentration  i n t h e l i q u i d f e e d 0.00 t o  -• -  170  0.237 m o l C02/mol a b s o r b e n t ; 20 °C; t o t a l p r e s s u r e  The  data  different  in  from  researchers  Tables  because  and  6.2 were o b t a i n e d  latter  2m  high)  from f a i r l y  and  therefore  well  t h e o r e t i c a l models. temperature concentration the C 0  2  changes  6.2  are  generally  provide  suited  i n t h e gas  other shorter  only  inlet  i n Tables  t h e c o l u m n . The p r e s e n t to  also  test  48 °C.  6.1  c o l u m n s ( u p t o 6.55 m  extensive concentration  The p r e s e n t are  used  and r e c o r d e d  tall  by  the  performance  overall concentration considerable.  phase ranged from  The  19.1 t o 0.0  and data of and C0  2  %,  l o a d i n g i n t h e l i q u i d v a r i e s f r o m 0.0 t o 0.583 m o l e s  o f C 0 / m o l e o f a b s o r b e n t a n d t e m p e r a t u r e c h a n g e d f r o m 15 2  to  significantly  reported  By c o n t r a s t , t h e d a t a  t e m p e r a t u r e measurements a l o n g are  to  measurements  1 to  outlet conditions.  height)  6.1  the  and  of p a c k i n g  14  103.15 k P a .  the  columns ( t y p i c a l l y  l i q u i d feed temperature  to  171  T a b l e 6.1: E x p e r i m e n t a l r e s u l t s f o r t h e C0 -NaOH  system.  2  Run  (#)  Tl  T2  T3  T4  T5  T6  A i r Flow Rate (mol/m s)  14..8  14..8  14..8  14..8  14..8  14..8  L i q u i d Flow (m /m h)  Rate  13..5  13..5  13..5  13..5  13..5  13..5  A b s o r b e n t Feed Cone, (kmol/m )  1 .2 .  1 .2 .  1 .2 .  1 .2 .  1 .2 .  1 .2 .  2..3 4..0 6..3 8..9  4..4 7..8 1 1 .8 . 14,.6  7..7 12..3 16..5 18..2  2  3  2  3  Gas C 0 iheight 0.00 m 1 .05 m 2.15m 3.25 m 4.35 m 5.45 m 6.55 m C0  2  2  Cone.(%) from t o p :  removal  i»  i*  (%)  75..6  OH Cone, (kmol/m ) ©height f r o m t o p : 0.00 m 0.750 1.05m 0.610 2.15m 0.420 3.25m 0.180 4.35 m -.5.45 m -.6.55 m -.-  i> i  i» i  »»  73.. 1  62,.2  1 .0 . 2..2 4..2 6..8 9.. 1  2..9 5..3 8..5 1 1 .2 . 12..3  »»  i*  •  «*  89..4  78,.4  1 .9 . 3,.7 6,.7 10,. 1 12,.5 »  86,.8  3  1.000 0.690 0.310 0.050 -.-.-.-  1.020 0.590 0.190 0.010 -.-.-.-  0.800 0.710 0.550 0.320 0.100 -.-.-  0.860 0.660 0.390 0.130 0.010 -.-.-  1.030 0.880 0.620 0.300 0.070  Mass B a l . E r r o r (%)  +1.54  -0.37  +1.91  +3.06  -1.24  -3.76  L i q . Temp (°C) @height from t o p : 0.00 m 1.05m 2.15m 3.25 m 4.35 m 5.45 m 6.55 m  15.0 17.0 20.0 23.0 -.-.-.-  16.0 20.0 25.0 29.0 -.-.-.-  16.0 21.5 26.5 29.0 -.-.-.-  18.0 19.0 20.5 24.0 26.0 -.-.-  16.5 19.0 23.0 26.5 27.0 -.- -  16.0 18.0 21.0 26.0 27.5  N o t e : F o r r u n T1 t o t 6 , t h e c o l u m n  was n o t  insulated.  172  Table 6.1(con't): r e s u l t s f o r t h e C02-NaOH s y s t e m .  Experimental Run  (#)  A i r Flow Rate (mol/m s)  T7  T8  T9  14.8  14.8  14 .8  14 .8  14.8  14.8  13.5  13.5  2  L i q u i d Flow (m /m h)  T1 0  T1 1  T12  Rate  9.5  9.5  1 3.5  13 .5  Absorbent Feed Cone, (kmol/m )  2.0  2.5  2 .0  2 .0  2.0  2.0  Gas C 0 C o n e . ( % ) ©height f r o m t o p : 0.00 m 1 .25 1, 05 m 2.95 2 15 m 6.15 3-, 25 m 1 1 .20 4 35 m 1 5.45 5.45 m • 6.55 m •  1 .70 3.50 7.05 12.85 18.60  1 .00 2 .65 5 .80 1 1.55 18 .45  1 .75 3 .60 6 .65 10 .90 15 .20  0.0 0.5 1.2 3.1 7.0 12.0 15.5  0.0 0.0 0.5 1 .4 3.7 8.2 15.4  C0  92.5  3  2  3  2  2  removal  (%)  93.0  OH~ Cone, ( k m o l / m ©height f r o m t o p : 0.00 m 1 .05 m 2.15m 3.25 m 4.35m 5.45 m 6.55 m  3  • •  • •  ' 95.5  • •  90 .0  100.0  100.0  ) 2.000 1 .800 1 .425 0.720 0. 137  2.500 2.000 2.275 1 .900 1 .800 1 .625 0.950 1 .075 0.180 0.370  1.500 1.350 1.060 0.625 0.243 -.-  1.530 900 (1.480) 900 1.475 900 (1.270) 750 0.930 600 0.470 150 0.080 0.480  Mass B a l . E r r o r  (%)•  L i q . Temp (°C) ©height f r o m t o p : 0.00 m 1.05 m 2.15m 3.25 m 4.35m 5.45 m 6.55 m  -1 .78  -2.23  -5.69  + 1 .50 + 1 .20 + 1 .4;  14.5 17.0 23.0 35.0 37.0  14.0 17.0 23.5 39.0 42.0  15.0 17.0 22.0 29.0 35.0  15.0 17.0 20.0 26.0 30.0  • •  • •  • •  N o t e : The v a l u e s i n ( ) a r e c a l c u l a t e d  • •  20.0 20.0 21 .0 23.5 28.0 35.0 37.5  21 .0 21 .0 22.0 23.0 26.0 33.0 39.0  f r o m mass b a l a n c e .  Experimental Run  (#)  T a b l e 6.2: r e s u l t s f o r t h e C0 -MEA  T1 3  2  T1 4  T1 5  system. T17  T16  A i r Flow Rate (mol/m s)  14.8  14.8  14.8  14.8  14.8  L i q u i d Flow (m /m h)  13.5  13.5  13.5  9.5  13.5  2  3  Rate  2  Absorbent Feed Cone, ( k m o l / m )  2.00  2.00  2.03  2.08  3.8  Gas C 0 C o n e . ( % ) ©height f r o m t o p : 0.00 m 0.0 1 .05 m 0.0 2.15m 0.4 3.25 m 1.0 4.35 m 3.3 5.45 m 8.3 6.55 m 15.3  0.0 0.6 1 .4 4.0 8.4 12.8 15.6  0.0 0.0 0.6 2.1 6.5 13.6 19.5  0.0 0.5 1 .3 3.9 8.9 13.8 15.5  0.0 0.0 0.8 2.0 5.3 10.2 15.6  3  2  C0  2  removal  (%)  100.0  100.0  100.0  100.0  100.0  C0 l o a d i n g ( m o l C 0 / m o l MEA) @height from t o p : 0.00 m 0. 000 0. 1 18 1.05m ( 0 . 000) ( 0 . 125) 2.15m ( 0 . 012) 0. 140 3.25 m 0. 025 ( 0 . 198) 4.35 m 0. 078 0. 295 5.45 m 0. 200 0. 400 6.55 m 0. 362 0. 480  0. 000 ( 0 . 000) 0. 013 ( 0 . 040) 0. 140 0. 302 0. 475  0. 000 ( 0 . 000) 0. 038 0. 090 0. 255 0. 425 0. 500  0. 237 ( 0 . 237) 0. 243 0. 255 0. 296 0. 350 0. 428  Mass B a l . E r r o r (%)  +2. 36  +0. 09  - 0 . 34  - 2 . 31  +0. 89  L i q . Temp (°C) @height from t o p : 0.00 m 1 .05 m 2.15m 3.25 m 4.35 m 5.45 m 6.55 m  19. 0 19. 0 19. 5 20. 0 23. 0 29. 0 34. 0  19. 0 20. 0 21 . 0 22. 0 28. 0 33. 0 34. 0  19. 0 19. 0 19. 0 21 . 0 25. 0 35. 0 37. 5  19. 0 19. 0 20. 0 26. 0 33. 0 41 . 0 39. 0  20. 0 20. 0 21 . 0 22. 0 26. 0 32. 0 36. 0  2  2  N o t e : The v a l u e s i n ( ) a r e c a l c u l a t e d  .  f r o m mass b a l a n c e .  174  Experimental Run  (#)  Table 6.2(con't): r e s u l t s f o r t h e C02-MEA  T18  A i r Flow Rate  T19  T20  system.  T21  T22  14.8  14.8  14.8  11.1  14.8  9.5  13.5  9.5  9.5  9.5  2.55  2.00  3.00  (mol/m s ) 2  L i q u i d Flow Rate  (m-Vm h) 2  Absorbent Feed Cone, (kmol/m )  2.00  2.00  3  Gas C 0 C o n e . ( % ) ©height f r o m t o p : 0.00 m 1 .05 m 2.15m 3.25 m 4.35 m 5.45 m 6.55 m  3.3 7.9 14.0 17.2 18.4 18.8 19.1  CO2 r e m o v a l  85.4  2  (%)  0.0 0.0 0.1 0.2 1 .4 4.8 11.5 100.0  C0 l o a d i n g ( m o l C 0 / m o l MEA) ©height f r o m t o p : 0.00 m 0.000 0.000 1 .05 m 0. 150 ( 0 . 0 0 0 ) 2.15m 0.362 (0.002) 3.25 m 0.482 0.005 4.35 m 0.032 (0.530) 5. 45 m 0.538 0.108 6.55 m 0.558 0.265 2  0. 0 0. 6 2. 8 7. 7 14. 2 17. 7 19. 2  0. 0 0. 0 0. 1 1 .2 6. 0 13. 2 19. 1  0. 0 0. 0 0. 1 1 .2 5. 3 12. 8 19. 1  100. 0  100. 0  100. 0  2  0. 000 0. 010 0. 070 0. 190 ( 0 . 366) 0. 474 0. 514  0. 000 ( 0 . 000) 0. 000 0. 030 0. 142 0. 325 0. 488  0. 000 0. 000 0. 000 0. 033 0. 125 0. 292 0. 443  Mass B a l . E r r o r  (%)  L i q . Temp (°C) ©height f r o m t o p : 0.00 m 1 .05 m 2.15m 3.25 m 4.35m 5.45 m 6.55 m  -0.94  +4,58  - 3 . 14  -1 . 19  + 0.92  20.0 27.0 36.0 43.0 42.0 41.0 36.0  19.0 19.0 19.0 19.0 20.0 24.0 30.0  19. 0 20. 0 22. 0 32. 0 47. 0 57. 0 48. 0  19. 0 19. 0 19. 0 21 . 0 26. 0 33. 5 37. 5  19. 0 19. 0 19. 0 21 . 0 29. 0 45. 0 47. 0  N o t e : The v a l u e s i n ( ) a r e c a l c u l a t e d from mass b a l a n c e .  175  6.1.1  EFFECT OF OPERATING  CONDITIONS  To show t h e e f f e c t o f v a r i o u s column  performance,  the C0  operating variables  concentration  2  p l o t t e d a g a i n s t t h e column h e i g h t  i n Figures  The e f f e c t o f CO2- l o a d i n g on t h e p r o f i l e 6.1 (Run T13 v s 0.0  to  T 1 4 ) . When t h e  0.118  approximately  while  the  profiles  are  6.1 t o  6.6.  i s shown i n  Figure  loading i s increased  keeping  same,  on  a l l other  the packing  height  from  conditions required  for  n e a r l y c o m p l e t e r e m o v a l i n c r e a s e d f r o m a b o u t 5.45 t o 6.55 m. This of  increase i s , of course,  free  due t o t h e r e d u c e d  absorbent f o r r e a c t i n g  availability  with the absorbed  carbon  dioxide.  Figure  6.2 (Run  concentration from  i n the inlet  approximately  concentration of l i q u i d  g a s . The to  81%  removal of C 0  when  the C0  v  effect  6.3 (Run T15 v s T 1 8 ) .  flow rate i s increased, the absorption  values  and  a b s o r b e n t . The i n c r e a s e  ( i i )higher  2  inlet  2  15% t o 19%. The  f l o w r a t e i s shown i n F i g u r e  C0  falls  2  c a p a c i t y o f t h e c o l u m n a r e i n c r e a s e d due t o : ( i )  k ° and a L  100%  T 1 8 ) shows t h e e f f e c t o f  i s r a i s e d from about  When t h e l i q u i d and  T16 v s  concentrations  rate higher  of  i n f r e e absorbent a l s o enhances  e f f e c t i v e mass t r a n s f e r c o e f f i c i e n t o f t h e l i q u i d  phase.  free the  176  For  absorbers chemical  without  absorption By  using  physical  r e a c t i o n ) , the primary  capacity i s to  e n h a n c e d by j u s t  removal  reducing (see Figure  The e f f e c t o f  the gas feed  rate.  reaction,  increasing the 6.4  the  the  absorbent  (Run T18 v s T 2 0 ) .  As  r a t e i n c r e a s e s the degree of  6.5 - Run T18 v s T 2 1 ) .  s o l v e n t type  d e m o n s t r a t e d by F i g u r e the column  way t o i n c r e a s e  with chemical  c o n c e n t r a t i o n a s shown by F i g u r e expected,  (absorption  increase the s o l u t i o n flow  c o n t r a s t , f o r gas a b s o r p t i o n  c a p a c i t y c a n be  solvents  on  the absorption  rate  is  6.6. T h e r e i s a l m o s t no d i f f e r e n c e i n  p e r f o r m a n c e when  u s i n g NaOH  o r MEA  under  the  c o n d i t i o n s o f Runs T11 a n d T14  (see Figure  6 . 6 ) . I t may  be  inferred  significant  difference  in  that  there  absorption capacity  is  no  when e i t h e r  used under t h e p r e s e n t  one o f  these  operating conditions.  solvents  is  177  0.0  12.0  6.0  18.0  C 0 Cone. (%) 2  Figure  6.1:  E f f e c t of C 0 l o a d i n g . The i n l e t C 0 l o a d i n g was i n c r e a s e d f r o m 0.0 (Run T13 - s o l i d c i r c l e s ) t o 0.118 (Run T14 - open s q u a r e s ) mol C 0 per-mol MEA. O p e r a t i n g c o n d i t i o n s : gas f l o w r a t e = 14.8 m o l / m s; l i q u i d f l o w r a t e = 13.5 m /m h; t o t a l MEA c o n c e n t r a t i o n = 2.0 k m o l / m ; i n l e t gas C 0 c o n c e n t r a t i o n = 15.5%. 2  2  2  2  3  2  3  2  178  C0 Figure  Cone. (%)  2  6.2: E f f e c t o f g a s C 0 c o n c e n t r a t i o n . The i n l e t C 0 c o n c e n t r a t i o n was i n c r e a s e d f r o m 15.6 % (Run T16 - open s q u a r e s ) t o 19.1 % (Run T18 - s o l i d c i r c l e s ) . Operating conditions: gas.flow rate = 14.8 m o l / m s; l i q u i d f l o w r a t e = 9 . 5 m /m h ; t o t a l MEA c o n c e n t r a t i o n = 2.0 k m o l / m ; i n l e t C 0 l o a d i n g = 0.0 m o l C 0 / m o l MEA. 2  2  2  3  2  3  2  2  179  6.0  0.0  Figure  C0  12.0 2  18.0  Cone. (%)  6.3: E f f e c t o f l i q u i d f l o w r a t e . The l i q u i d f l o w r a t e was i n c r e a s e d f r o m 9.5 ( R u n T t 8 - s o l i d c i r c l e s ) t o 13.5 (Run T15 - open s q u a r e s ) m /m s. O p e r a t i n g c o n d i t i o n s : g a s f l o w r a t e = 14.8 m o l / m s; t o t a l MEA c o n c e n t r a t i o n = 2.0 k m o l / m ; i n l e t C 0 l o a d i n g = 0.0 mol C 0 / mol MEA; i n l e t g a s C 0 c o n c e n t r a t i o n = 19.5%. 3  2  2  3  2  2  2  180  0.0  6.0  12.0  18.0  C0 Cone. (%) 2  ure 6.4:  E f f e c t o f a b s o r b e n t c o n c e n t r a t i o n . The t o t a l MEA c o n c e n t r a t i o n was i n c r e a s e d from 2 . 0 (Run T18 s o l i d c i r c l e s ) t o 2 . 5 5 (Run T20 - open s q u a r e s ) k m o l / m . O p e r a t i n g c o n d i t i o n s : gas f l o w r a t e = 14.8 m o l / m s; l i q u i d f l o w r a t e = 9 . 5 m /m h ; i n l e t CO2 l o a d i n g = 0.0 mol C 0 / mol MEA; i n l e t g a s C02 c o n c e n t r a t i o n = 19.1%. 3  2  3  2  2  181  0.0  6.0  12.0  18.0  C 0 Cone. (%) 2  F i g u r e 6.5: E f f e c t of gas flow r a t e . The gas flow r a t e was i n c r e a s e d from 11.1 (Run T21 - open squares) t o 14.8 (Run T18 - s o l i d c i r c l e s ) mol/m s. O p e r a t i n g c o n d i t i o n s : l i q u i d flow r a t e = 9.5 mVm h; i n l e t C 0 l o a d i n g = 0.0 mol C 0 / mol MEA; i n l e t gas C02 c o n c e n t r a t i o n3 = 19.1%; total MEA c o n c e n t r a t i o n = 2.0 kmol/m . 2  2  2  182  I  0.0  6.0  C0 Figure  12.0 2  Cone.  (%)  6.6: E f f e c t o f a b s o r b e n t t y p e . The s o l v e n t t y p e was c h a n g e d f r o m NaOH (Run T11 - s o l i d c i r c l e s ) t o MEA (Run T14 - open s q u a r e s ) . O p e r a t i n g c o n d i t i o n s : g a s f l o w r a t e = 14.8 m o l / m s; l i q u i d f l o w r a t e = 13.5 m /m h; t o t a l a b s o r b e n t c o n c e n t r a t i o n = 2.0 k m o l / m ; i n l e t g a s C02 c o n c e n t r a t i o n = 15.5%. 2  3  2  3  183  6.2  COMPARISON BETWEEN FULL-LENGTH ABSORBER PERFORMANCE  AND  THEORETICAL PREDICTIONS*  Computer p r o g r a m s , a l g o r i t h m and 3.2,  were  6.2.1  were d e v e l o p e d  computation procedures  used  performance  which  to  predict  the  b a s e d on  described  in  full-length  Section absorber  f o r t h e C02 NaOH and CO2-MEA s y s t e m s . -  SOURCES OF BASIC INFORMATION  B e f o r e t h e model parameters  (e.g.  e q u a t i o n s can  mass  transfer  be e v a l u a t e d ,  coefficients,  various  solubility,  r e a c t i o n r a t e c o n s t a n t , e t c . ) a r e needed.  These  may  measurements  be  obtained  correlations.  from  experimental  Great caution  has t o  parameters  be e x e r c i s e d  t h e r e a r e c o n s i d e r a b l e d i s c r e p a n c i e s between  the  Khurana,  [ 1 0 5 ] and t h e s e  prediction  or  because  previously  r e c o r d e d d a t a a s r e p o r t e d by K e l l y e t a l . [ l 0 6 ] a n d R a a l  the  the  d i s c r e p a n c i e s can s t r o n g l y  and  affect  results.  * Some e x p l o r a t o r y results on the comparison between absorber performance and theoretical predictions were p r e s e n t e d at 38th Canadian Chemical E n g i n e e r i n g Conference (Edmonton, O c t . 2-5, 1988) and were p u b l i s h e d in "Gas Separation Technology" edited by V a n s a n t and Dewolfs, E l s e v i e r , p. 38-90, 1990.  184  Some t y p i c a l v a l u e s o f the computer models system  estimating k al.[35]  several and  G  were  satisfactory and  are l i s t e d  (Run T9) a n d T a b l e  Although  a , the expressions v  because  are  in  CC>2 NaOH -  (Run T 2 2 ) .  available  proposed were  for  by Onda_ e t  found  to  f o r c o n v e n t i o n a l p a c k i n g s by K e l l y e t a l .  i n Berl  was  coefficient  used was  A  new s e t o f d a t a f o r t h e  Saddles packing r e c e n t l y in  this  by P a n d y a [ 5 4 ] .  by  The  using  be [106]  liquid  reported  heat  the  by  transfer  correlation  The v a l u e s f o r t h e t o t a l h e a t  of  i s t h e sum o f t h e h e a t o f s o l u t i o n a n d t h e  h e a t o f r e a c t i o n , were t a k e n Riesenfeld  model.  calculated  a b s o r p t i o n , which  and  they  used  6.3 f o r  2  correlations  chosen  mass t r a n s f e r  suggested  i n Table  6.4 f o r C0 -MEA s y s t e m  Sanyal et a l . [108].  ChofllO]  these b a s i c parameters  from Danckwerts [ 1 8 ] and  [ 5 ] f o r t h e C0 -NaOH 2  a n d C0 -MEA  Kohl  systems,  2  respectively.  One o f t h e most i m p o r t a n t p a r t s o f g a s a b s o r p t i o n chemical  reaction  modelling  calculation. Unlike physical  i s the  enhancement  gas a b s o r p t i o n , t h e  factor k  L  values i n the chemical  a b s o r b e r s change s i g n i f i c a n t l y  the bottom t o  due t o  r e a c t i o n as effect will  the top  previously  the e f f e c t  mentioned  a l s o be d e m o n s t r a t e d  in  of the  Section  and  I  from  chemical  2.3.2.  i n the following  with  This  section.  185  T a b l e 6.3: L i s t o f o p e r a t i n g c o n d i t i o n s a n d p a r a m e t e r s f o r Run T9 (C0 -NaOH s y s t e m ) . 2  Property L  (m /m h) 3  C  s)  2  0.413  14.8  14.8  0.1  C 0 2  0. 185  15.0  Temp. (°C)  35.0  D  A  (m /s)  1.518x10 -9  1 .803x10"  D  (m /s)  0.893X10"  9  B  1 .060X10"  k  3.168x10"  6  G  2  2  (kmol/m  s kPa)  2  k ° (m/s)  6.283x10  L  a  (m /m ) 2  v  H h  (kmol/m kPa) 3  G  k  2  H  R  I  (kj/s m  2  - 5  150.  3  °K)  3.168x1O"  9  6.846X10"  4  0.099  Onda e t a l . [35]  1 .076X10"  4  Pohorecki and Monuik [ 1 1 1 ] Pandya [ 5 4 ]  1 .025X10  4.574X10  (kJ/kmol)  1.021x10 + 5  1 .021X10 48.7  Danckwerts and Alper [5]  Cho [1103  5  0.099 + 4  Danckwerts and Sharma [ 1 ]  Onda e t a l . [35]  150.  2.274x10"  90.6  9  6  (m /kmol s) 3  Source Experiment  13.5  2.0  3  (mol/m  Column b o t t o m  13.5  2  (kmol/m )  B  Gj V  Column t o p  Pohorecki and Monuik [ 1 1 1 ]  + 4  + 5  Danckwerts!18] Welleck e t a l . [89];  186  T a b l e 6.4: L i s t o f o p e r a t i n g c o n d i t i o n s a n d p a r a m e t e r s f o r Run T22 (C0 -MEA s y s t e m ) . 2  Property L  (m /m 3  2  Column t o p h)  T o t a l MEA  (kmol/m ) 3  Loading  Column b o t t o m  9.5  9.5  3.0  3.0  0.0  0.443  Source Experiment  (mol C 0 / m o l MEA) 2  Gj  (mol/m  s)  2  14.8  14.8  0.0  yco2  0.191  19.0  Temp. (°C)  47.0  D  A  (m /s)  1.209X10"  D  B  (m /s)  k  2  2  G  (kmol/m  s kPa)  2  k ° (m/s) 2  H h  (m /m )  v  3  k  2  H  R  Thomas a n d Furzer [112]  0.756x10 -9  0.974x10~  9  Thomas a n d Furzer [112]  3.168x10  3. 1 6 8 X 1 0 ~  (kJ/sm  2  - 5  °K)  4  0.099 0.401X10  (kJ/kmol)  0.937xl0  3  70.9  6.115x10~  5  135.  6.220xl0~  (m /kmol s)  I— •  6  135.  3  (kmol/m kPa)  G  9  5.387xl0  L  a  1.558x10~  9  2.049X10"  + 5  1.854X10 0.937X10 24. 13  Onda e t a l . [35] Cho [ 1 1 0 ] Onda e t a l . [35]  4  0.099 + 4  6  Pohorecki and Monuik [ 1 1 1 ] Pandya [ 5 4 ]  + 4  Blauwhoff et a l . [43]  + 5  Danckwerts[18] Welleck e t a l . [89]  187 For the r e a c t i o n of second-order avoid  2  r e a c t i o n can  complex  equations  C0 -NaOH a n d C0 -MEA s y s t e m s ,  numerical  available  be assumed  f o r the  2 . 3 . 2 ) . The e x p l i c i t  et a l .  [ 8 9 ] was  used  [ 1 , 17,  calculation,  Section  the  2  18, 5 4 ] . To  there  approximate  are  a  few  solutions  (see  equation presented  (see Equation 2.25).  by  Welleck  However,  the  information  r e g a r d i n g t h e r a t e c o n s t a n t and p h y s i c o - c h e m i c a l  properties  of  the  system  must  be  known  before  the  enhancement f a c t o r c a n be e v a l u a t e d .  The  rate  temperature  range  i n t e r e s t , has Moniuk  l o  constant  of  and a t  been  C0 -NaOH 2  the i o n i c  by  of  in  the  practical  Pohorecki  and  [111] a s  9  where I  k  2,NaOH  11.895  =  -  2  second-order  9  C  i s the i o n i c strength  c  F o r C0 -MEA s y s t e m ,  l o  strength  recently correlated  + 0.221I  its  reaction,  k  2,MEA =  2382/T -  0.016(I )  2  C  (6.1 )  of the s o l u t i o n .  Blauwhoff  et  a l . [43]  correlated  rate constant as  1 0  -  9 9  _  2152/T  (6.2)  188  The  Henry's  solution  constant  i s estimated  log(H/H ) =  where K  s  S  solubility  using the following  -K I  w  f o r CO2  (6.3)  i s t h e sum o f t h e c o n t r i b u t i o n s due t o i o n s i n t h e  Henry's constant  of C 0  2  [18], H  2  This c o r r e l a t i o n  For  the  salting-in  w  denotes the  i n water:  = 9.1229 - 5 . 9 0 4 4 X 1 0 ~ T + 7 . 8 8 5 7 x 1 0 ~ T  w  NaOH  expression:  C  l i q u i d p h a s e a n d r e p o r t e d by D a n c k w e r t s  log(H )  in  was t a k e n  5  from P o h o r e c k i  C0 -MEA s y s t e m ,  Hikita  2  2  and Moniuk  et  (6.4)  [111],  a l . [49] found  a  e f f e c t c o r r e l a t e d by  l o g ( H / H ) = 0.3[MEA]/(1 w  K[MEA])  -  K I S  (6.5)  C  where K = 1./(1.2850 - 0.001(T - 3 1 4 . 5 5 1 3 ) ) 2  The  diffusivity  were r e p o r t e d by Furzer  data  f o r C0 -NaOH a n d C0 -MEA  [ 1 1 2 ] . The  e f f e c t of temperature  ab< 2>/ ab< 1> T  D  2  D a n c k w e r t s a n d Sharma  c a l c u l a t e d u s i n g an e q u a t i o n  D  2  T  =  systems  [ 1 ] a n d Thomas  and  on d i f f u s i v i t y  is  s u g g e s t e d by R e i d e t a 1 . [ 1 1 3 ] :  ((Tc-T^/fTc-T;,))'  1  (6.6)  189  where T  is  the c r i t i c a l  index n  is  related to  solvent.  I n o u r c a s e , n i s e q u a l t o 3.  c  The  data  viscosity, Handbook,  the  f o r other  specific  heat,  heat of  parameters e t c . were  the solvent.  vaporization  such taken  as  Fact  should  be  that  p a r a m e t e r s h a v e been r e p o r t e d _  2  p e r i o d of time.  f o r designing  very  difficult  the  quite  from  Perry's  [ 1 5 ] , and  gas  information  on  studied  shows t h a t a c q u i r i n g t h e  fora  long  fundamental  absorbers with chemical reaction  and time-consuming.  some  r e c e n t l y even t h o u g h t h e  systems have been  This  data  the  Book by Dow C h e m i c a l Company [ 7 4 ] .  noted  CC>2-NaOH a n d C 0 M E A  of  The  density,  Gas P u r i f i c a t i o n by K o h l a n d R i e s e n f e l d  Gas C o n d i t i o n i n g  It  temperature of  is  190  6.2.2 COMPARISON OF RESULTS  The  computer  against  predictions  in  virtually present  predictions  identical  lines)  temperatures T9)  previous  confirming  of experimental  gas c o n c e n t r a t i o n s ,  results  the v a l i d i t y  are  of the  ( p o i n t s ) and  predicted  l i q u i d compositions  a l o n g t h e c o l u m n a r e shown i n F i g u r e s 6.7  a n d 6.8 (Run T22) f o r t h e C0 -NaOH a n d C0 -MEA 2  r e s p e c t i v e l y . The l i s t s c o n d i t i o n s f o r Run T9 and  and  programs.  Typical plots (solid  thereby  reported  tested  e n s u r e t h a t t h e p r o g r a m s w o r k e d p r o p e r l y . As c a n be s e e n the  results  first  to  6.5,  calculated  were  previously  Table  some  models  of basic  a n d Run T22 a r e  6.4, r e s p e c t i v e l y .  operating  given i n Tables  6.3  The a g r e e m e n t between t h e r e s u l t s i s  g e n e r a l l y v e r y good t h e r e b y the mathematical  (Run  systems,  2  parameters and  and  model.  again confirming the v a l i d i t y of  A d d i t i o n a l evidence  f o r the  good  a g r e e m e n t i s p r o v i d e d by F i g u r e s 6.10 t o 6.13.  As  s e e n f r o m F i g u r e s 6.7a a n d 6.8a, t h e g a s a n d  temperature  profiles  differ  significantly  near t h e  b o t t o m where t h e e n t e r i n g g a s i s r a p i d l y h e a t e d  by t h e  liquid column  191  T a b l e 6.5: C o m p a r i s o n between t h e c a l c u l a t i o n r e s u l t s p r e v i o u s r e p o r t s a n d f r o m t h i s work.  from  Source and Conditions  Computed Height  This  work  Pandya [ 5 4 ] C0 -MEA s y s t e m C o l u m n : 0.1m I D , 12.7mm R a s c h i g r i n g s Operating Conditions: gas r a t e = 1573 kg/m h l i q u i d r a t e = 13.68 m /m s T o t a l MEA c o n e . = 2.5 k m o l / m l o a d i n g = 0.15 ( t o p ) a n d 0.4 ( b o t t o m ) CQ2 0 . 0 1 ? 6 ( t o p ) a n d 0.176 ( b o t t o m ) Column temp. = 46 °C Column P r e s s u r e = 2020 k P a .  0.84 m  0.84 m  D a n c k w e r t s a n d Sharma [ 1 ] C0 MEA system C o l u m n : 2.27m, 38.1mm R a s c h i g r i n g s Operating Conditions: gas r a t e = 2628 kg/m h l i q u i d r a t e = 60.84 m /m s T o t a l MEA c o n e . = 2.5 k m o l / m l o a d i n g = 0.15 ( t o p ) a n d 0.4 ( b o t t o m ) C02 0 . 0 2 5 ( t o p ) a n d 0.25 ( b o t t o m ) Column temp. = 30 °C Column P r e s s u r e = 2020 k P a .  1 .42 m  1.51 m  2  2  3  2  3  Y  =  _  2  2  3  2  3  Y  =  Alper [56] 1.54 m C0 -NaOH s y s t e m C o l u m n : 0.1m I D , 12.7mm R a s c h i g r i n g s Operating Conditions: gas r a t e = 1831 kg/m h l i q u i d r a t e = 10.08 m /m s [ N a ] c o n e . = 1.2 k m o l / m [OH~] = 0 . 6 ( t o p ) a n d 0 . 0 8 ( b o t t o m ) k m o l / m CQ2 0 . 0 6 6 ( t o p ) a n d 0.115 ( b o t t o m ) Column temp. = 25 °C Column P r e s s u r e = 101 k P a . 2  2  3  +  2  3  3  Y  =  1 .48 m  192  Figure  6.7: P r e d i c t e d ( l i n e s ) a n d e x p e r i m e n t a l (points) results f o rthe C 0 NaOH s y s t e m (Run T 9 ) : [ a ] Temperature p r o f i l e s f o r the l i q u i d ( s o l i d l i n e ) and g a s p h a s e s ( d o t t e d l i n e ) , Open s q u a r e s a r e the e x p e r i m e n t a l measurements o f t h e l i q u i d temperature; [b] concentration p r o f i l e s of C 0 (open c i r c l e ) a n d NaOH ( s o l i d c i r c l e ) ; [ c ] Enhancement f a c t o r . -  2  2  193 o  0.0  Figure  6.8:  3.0  Distance from the bottom (m)  6.0  P r e d i c t e d ( l i n e s ) and experimental (points) r e s u l t s f o r t h e C 0 - MEA s y s t e m (Run T 2 2 ) : [ a ] Temperature p r o f i l e s f o r the l i q u i d ( s o l i d l i n e ) and g a s p h a s e s ( d o t t e d l i n e ) , Open s q u a r e s a r e t h e e x p e r i m e n t a l measurements o f t h e l i q u i d ... temperature; [b]concentration p r o f i l e s of C 0 (open c i r c l e ) a n d l o a d i n g ( s o l i d c i r c l e ) ; [ c ] Enhancement f a c t o r . 2  2  194  descending l i q u i d .  Higher up  liquid  reach a  temperatures  i n the column, maximum and  the gas  then become  s i m i l a r r e s u l t i n g from the f a c t s that the heat c a p a c i t y the mass flow rate the gas phase.  of the l i q u i d are  T h i s evidence  s t a t e d i n S e c t i o n 3.2.2  also  higher  confirms  6.7b-c  the  g r a d i e n t s of  gas and  6.8b-c  liquid  bottom part of the column. f o r c e between  the  composition  phases r e s u l t i n g  assumption  as  of  a  shown  (see F i g u r e  6.7),  profiles to higher higher  at  in  For  Figures  absorption  6.7c  and  is  6.8c.  therefore  i n s t a n c e , i n the case of Run factor  increases  about 48 at the column bottom to about 90 at the column T h i s means that the  absorption  i s 48 to 90 times higher  rate with chemical  than without  chemical  Near the top of the column, the reactant is relatively  high and,  therefore,  r i g h t a f t e r being d i s s o l v e d at  the  i t varies considerably  enhancement  the enhancement  the  driving-  greater changes o c c u r r i n g i n  constant  generally j u s t i f i a b l e .  liquid,  and  steeper  f a c t o r depends s t r o n g l y on  c o n c e n t r a t i o n of both gas and along the column with the  in  of  the same.  relatively  These are due  r a t e . Since the enhancement  lower s e c t i o n  show  and  assumption  that-the temperatures of the gas  and  very  than those  l i q u i d phases along the column are approximately  Figures  and  the The not T9 from top.  reaction  reaction.  concentration  most of C O 2 i s  the i n t e r f a c e . As a  consumed result,  195  the  reaction  zone  is  located  interface resulting  in  higher  factor.  On t h e o t h e r  the c o n c e n t r a t i o n the C O 2 higher  hand,  close values  of  the g a s - l i q u i d the  enhancement  near t h e bottom of the  of the l i q u i d  concentration  to  at  the  reactant  column,  i s much l o w e r  interface  is  but  considerably  by c o m p a r i s o n w i t h t h a t a t t h e t o p o f t h e c o l u m n . The  C O 2 can  then d i f f u s e  deeply  reacting with the l i q u i d  into  the l i q u i d  film  r e a c t a n t . As a r e s u l t ,  before  the reaction  z o n e i s l o c a t e d f u r t h e r away f r o m t h e i n t e r f a c e r e s u l t i n g i n r e d u c e d enhancement f a c t o r s .  Since  t h e enhancement f a c t o r  i s a complex f u n c t i o n  the hydrodynamic c o n d i t i o n s of t h e  absorber  physico-chemical  system, i t i s  p r o p e r t i e s of the  a s w e l l a s the.  t o make d i r e c t c o m p a r i s o n s b e t w e e n t h e r e s u l t s other values  experimental  o f t h e enhancement f a c t o r f o r C 0 - N a O H a b s o r p t i o n 2  a l . [ 1 4 2 ] a n d Onda  explicitly  et al.[l43].  reported  As c a n be  6.6, t h e enhancement f a c t o r s o b t a i n e d the  difficult  from t h i s and  s t u d i e s . To o u r k n o w l e d g e , o n l y - 2 s e t s o f  packed columns have been  same  authors.  order  as  those  reported  by  by M e r c h u k  seen from  i n t h i s study the  of  in et  Table a r e of  afore-mentioned  196  T a b l e 6.6: C o m p a r i s o n o f enhancement f a c t o r v a l u e s o b t a i n e d f r o m M e r c h u k e t a l . [ l 4 2 ] , Onda e t a l . [ l 4 3 ] a n d Run T 9 .  Source  Enhancement  Merchuk e t a l . [ 1 42]  factor  6 t o 60  C o l u m n : 0.25m I D , 0.335m h i g h 25.4mm c a r b o n R a s c h i g r i n g s Conditions: g a s r a t e = 2800 t o 3000 kg/m h l i q u i d r a t e = 3.0 t o 10.0 m /m h NaOH c o n e . = 0.5 t o 1.0 kmol/m CO? c o n e . = 8.0 t o 90.0 % Column t e m p e r a t u r e = 29.0 t o 32 °C 2  3  2  3  Onda e t a l .  [143]  10 t o 150  C o l u m n : 0.076m I D , 0.4m h i g h 6.0mm c e r a m i c R a s c h i g r i n g s Conditions: l i q u i d r a t e = 6.37 t o 39.25 m /m h NaOH c o n e . = 0.5 t o 3.0 kmol/m C 0 cone. = 1 0 0 % Column t e m p e r a t u r e = 15 t o 45 °C 3  2  3  2  T h i s work - Run T9  48 t o 90  C o l u m n : 0.10m I D , 4.35m h i g h 12.7mm c e r a m i c B e r l s a d d l e s Conditions: g a s r a t e = 1545 kg/m h l i q u i d r a t e = 13.5 m /m h NaOH c o n e . = 0.413 t o 2.0 k m o l / m C 0 c o n e . = 1.0 t o 18.45 % Column t e m p e r a t u r e = 15.0 t o 35.0 °C 2  3  2  3  2  197  COMPARI SON AT HIGH LOADING  When t h e CO2 l o a d i n g a t t h e column bottom reached  0.5  moles of CO2 p e r mole of amine f o r t h e CC^-MEA system, t h e difference  between  s i g n i f i c a n t as  the  results  shown by F i g u r e  and  prediction  are  6.9 (Run T 1 6 ) . I f o n l y  t e r m i n a l c o n d i t i o n s a r e c o n s i d e r e d , good agreement would deduced.  Nevertheless,  the discrepancy  between  p r o f i l e s i s l a r g e (see s o l i d  l i n e and p o i n t s ) .  that a  predictions  comparison  o f model  r e s u l t s a t t h e absorber  and  be  t h e two  This  shows  experimental  i n l e t and o u t l e t a r e i n s u f f i c i e n t t o  v a l i d a t e models.  One  reason  f o r t h e d i s c r e p a n c y i n t h i s case may be due  t o b i c a r b o n a t e f o r m a t i o n , which becomes important as t h e CO2 moles of CO2 per mole  l o a d i n g approaches 0.5 bicarbonate formation p r e s e n t model.  was not taken  Another reason  of MEA; t h e  i n t o account  may be because t h e r e a c t i o n  r a t e i s a f f e c t e d by t h e i o n i c c o n c e n t r a t i o n which included i n the rate constant increases  with  information reaction with  the  on  ionic  variation  ionic  i n rate  strength.  studied extensively for P o h o r e c k i and Moniuk  (Equation  strength  s t r e n g t h on t h e r a t e c o n s t a n t  but constant  i s w e l l known -  reported  was not  6.2). The l o a d i n g there  is  no  f o r CO2-MEA  The e f f e c t of  t h e C02 NaOH [111 ]  i n the  the i o n i c  and has been  system. F o r example, that  the value  of  3.0  0.0  s.o  Distance from the bottom (m)  Figure  6.9: C o n c e n t r a t i o n o f C 0 i n t h e g a s p h a s e f o r Run T16. Open c i r c l e s r e p r e s e n t experimental measurements; t h e s o l i d l i n e and d o t t e d l i n e s denote t h e p r e d i c t e d v a l u e s u s i n g a column c o m p r i s e d o f s i x and f i v e s e c t i o n s , r e s p e c t i v e l y . (Operating c o n d i t i o n s : gas flow r a t e = 14.8 m /m h ; l i q u i d f l o w r a t e = 9.5 m /m h; i n l e t C 0 l o a d i n g = 0.0 m o l C 0 / m o l MEA; i n l e t g a s C02 c o n c e n t r a t i o n = 15.5%; t o t a l MEA c o n c e n t r a t i o n = 2.0 kmol/m .) 2  3  3  2  2  2  2  3  199  k  2  by  NaOH i n c r e a s e s  s t r e n g t h was  more  f r o m 0.0  increased  times  t o 3.8  both  t h e r e a c t i o n mechanism  i n f l u e n c e t h e enhancement g o o d a g r e e m e n t was To c o n f i r m five  this,  factor,  not obtained  of  the  leaving  section, loading  and  entering  at  As shown by  the dotted  between t h e p r e d i c t e d and again  very  good.  and t h e r a t e  the high CO2  absorber  the  r e s p e c t i v e l y . Under t h e s e r a n g e d f r o m 0.00  effect  constant  i t i s not s u r p r i s i n g  experimentally determined compositions phases  ionic  systems.  t h e c a l c u l a t i o n s were r e p e a t e d  sections  the  3  -  Since  when  kmol/m . T h i s  be f u r t h e r s t u d i e d f o r C 0 2 a m i n e  should  top  4  than  loadings.  f o r j u s t the  and  using  of the l i q u i d  bottom  that  of  and gas  the  c o n d i t i o n s , the  the  lowest  solution  t o 0.425 m o l e s C O 2 p e r m o l e o f line  in Figure  experimental  6.9, values  the  MEA.  agreement  becomes  once  200  OVERALL  COMPARISON  Due  t o the  difficult  to  Therefore,  l a r g e amount  illustrate  liquid 6.11,  the comparison  the comparisons  o f CO2 c o n c e n t r a t i o n ,  6.12 a n d 2  NaOH c o n c e n t r a t i o n ,  a p p r o a c h e s 0.5  a m i n e f o r t h e C0 -MEA s y s t e m 2  of t h e bottom s e c t i o n s not included  in  i tis  tabular  form.  C0  predictions loading  2  a r e shown i n F i g u r e s  6.13, r e s p e c t i v e l y .  loading  in  data,  between r e s u l t s and  temperature f o r a l l runs  when C 0  are  of experimental  Since  the  moles of C 0  the comparisons.  As  6.10,  predictions p e r mole  2  are not accurate,  o f runs T15, T16,  predictions are obtained.  two  a r e , on t h e a v e r a g e , a b o u t 12%.  I t was a l s o f o u n d  T 1 8 , T20 a n d T21 c a n be s e e n  The d i s c r e p a n c i e s  t h a t t h e model  I n some c a s e s ,  a  (concentrations)  in  i n t h e input data  large differences  i n the predicted  between t h e  quite  deviations of  height.  c a l c u l a t i o n s a r e shown i n T a b l e 6.7 (Run T 9 ) .  from  results  a p p e a r s t o be  s e n s i t i v e t o t h e mass b a l a n c e . few p e r c e n t  of  the r e s u l t s  t h o s e f i g u r e s , good a g r e e m e n t s b e t w e e n e x p e r i m e n t a l and  and  can Some  result sample  I f the  liquid  concentration  a t t h e c o l u m n b o t t o m i s r e d u c e d by 0.2 k m o l / m  (10% of  the  total  deviates  by 13.9%. H o w e v e r , i f t h e c o n c e n t r a t i o n  concentration),  the height  prediction is  further  r e d u c e d by 15%, t h e d e v i a t i o n i s e x p o n e n t i a l l y  increased  about 26%.  the  The  effect  of concentration  on  3  to  absorber  201  height  prediction  approached.  This  factor  the  and  dependent  on  the  is  i s not  fluid  be  theoretical  as  data  absorption  concentrations. for v e r i f y i n g  important  models.  larger  surprising  specific  good e x p e r i m e n t a l should  even  as  when  saturation  s i n c e the rate  enhancement  are  Therefore,  strongly obtaining  mathematical  developing  more  is  models rigorous  202  F i g u r e 6.10: C r o s s p l o t o f p r e d i c t e d a n d m e a s u r e d C O 2 c o n c e n t r a t i o n s i n the gas phase.  203  Figure  6.11:  Cross p l o t of p r e d i c t e d and measured concentrations in the l i q u i d phase.  NaOH  204  o  0.00  F i g u r e 6.12:  C0  0.25  2  Loading, exp.  C r o s s p l o t o f p r e d i c t e d and m e a s u r e d l o a d i n g i n t h e MEA solution.  0.50  C0  2  205  Figure 6.13:  Cross plot of predicted and measured temperatures in the l i q u i d phase.  206  T a b l e 6.7: E f f e c t o f mass b a l a n c e on t h e h e i g h t p r e d i c t i o n f o r Run T9 (NaOH-C0 s y s t e m ) . O p e r a t i n g C o n d i t i o n s : g a s r a t e = 1545 kg/m h ; l i q u i d r a t e = 13.5 m /m h; NaOH c o n e . = 0.413 t o 2.0 k m o l / m ; C 0 c o n e . = 1.0 t o 18.45 %; Column t e m p e r a t u r e = 15.0 t o 35.0 °C 2  2  3  2  3  2  Mass b a l a n c e a t Column b o t t o m  Predicted height  Deviation  C - 0.% o f 2.0 k m o l / m ( a t 0.37 k m o l / m )  3  4.40 m  0.0%  C - 10% o f 2.0 k m o l / m ( a t 0.17 k m o l / m )  3  5.01 m  13.9%  C - 15% o f 2.0 k m o l / m ( a t 0.07 k m o l / m )  3  5.56 m  26.4%  B  3  B  3  B  3  207  EFFECT  OF BASIC  Since  PARAMETERS  the uncertainties associated  with the data  c o r r e l a t i o n s a v a i l a b l e i n t h e open l i t e r a t u r e is  useful  to  know  the degree  of  results.  T9  the deviation  a r e used  to illustrate  r e s u l t s when v a l u e s  ranges  parameters. 6.8.  of  L  of  these  The c o n d i t i o n s o f R u n i n the  predicted  v  o r d e c r e a s e by 2 0 % ; t h e s e  uncertainty  associated  for  are these  The c a l c u l a t e d r e s u l t s a r e s u m m a r i z e d i n  Table  A s c a n be s e e n , t h e i m p a c t o f t h e i n t e r f a c i a l a r e a  t h e enhancement  i t  o f k g , k ° , a , H, a n d I i n t h e c o m p u t e r  model a r e f o r c e d t o i n c r e a s e typical  are high,  importance  p a r a m e t e r s on t h e _ p r e d i c t e d  or  factor  a r e as  high  as 26.1% and  and  20.4%,  respectively.  On t h e o t h e r  hand, t h e impact o f t h e p h y s i c a l  mass t r a n s f e r  coefficients  i s rather small  Henry's constant,  To fast  identify  or  whether r e a c t i o n  slow,  that  of  i n t h e l i q u i d phase  i s  H, i s m o d e r a t e .  Levenspiel  while - -  [ 3 0 , 141] s u g g e s t e d  measurement o f t h e s o - c a l l e d f i l m  conversion  that  a  parameter  be  used:  M =  maximum p o s s i b l e c o n v e r s i o n 7 ——~ maximum d i f f u s i o n t r a n s p o r t  = <2 C  C * 5)/{(D /8)  k  = k  2  A f i  B  A  C * D /(k °) B  A  L  2  C  A f i  i n liquid film through the f i l m }  208  If  the  occurs  value of  M i s much g r e a t e r  i n the l i q u i d  the f i l m ,  and  o t h e r h a n d , no r e a c t i o n  b u l k volume  of the  becomes t h e c o n t r o l l i n g f a c t o r when M Run T 9 a s column a r e  w e l l as  a l l reaction  f i l m , and e f f e c t i v e c o n t a c t i n g a r e a  t h e c o n t r o l l i n g r a t e . On t h e place i n  1,  than  other  w e l l over  runs, the  100. I t  e f f e c t s of the i n t e r f a c i a l on t h e h e i g h t p r e d i c t i o n  «  i s not  takes  liquid  phase  1. I n t h e case  values of  is  of  M along  the  surprising that  the  a r e a a n d t h e enhancement  are therefore very  high.  factor  209  T a b l e 6.8: E f f e c t s o f m a j o r p a r a m e t e r s on t h e h e i g h t p r e d i c t i o n f o r Run T9 ( N a O H - C O o ) . O p e r a t i n g C o n d i t i o n s : g a s r a t e = 1545 kg/m h ; l i q u i d r a t e = 13.5 m /m h; NaOH c o n e . = 0.413 t o 2.0 kmol/m ; C 0 c o n e . = 1.0 t o 18.45 %; Column t e m p e r a t u r e = 15.0 t o 35.0 °C 2  3  2  3  2  The n o r m a l p r e d i c t e d h e i g h t  Parameter k  a  G  v  Deviation  4.28 m 4.69 m  2.7 6.4  % %  20% 20%  4.36 m 4.56 m  0.9 3.6  % %  + 20% 20%  3.70 m 5.55 m  15.9 % 26. 1 %  20% 20%  3.94 m 5.19 m  10.4 % 17.9 %  + 20% 20%  3.86 m 5.30 m  12.3 % 20.4 %  +  —  I  Predicted height  + 20% 20%  —  H  = 4.40 m  -  210  CHAPTER 7 RESULTS AND  DISCUSSIONS: COMPARISON BETWEEN FULL-LENGTH  ABSORBER PERFORMANCE AND  The  PREDICTIONS BASED ON  o b j e c t i v e of t h i s c h a p t e r  r e s u l t s of the  PPT  design  verify  the  procedure proposed i n Chapter  3.  The  v a l i d a t i o n i s based  and  a PPT  7.1  V E R I F I C A T I O N USING R -CONCENTRATION DIAGRAM  short-cut  on  using  i s t o t e s t and  PPT  R ~concentration  diagrams  v  procedure.  y  The  absorption  of C 0  into  2  NaOH s o l u t i o n s was  d e m o n s t r a t e t h e p e r f o r m a n c e o f PPT. i n the  PPM  and  These  changes  are  assume t h a t b o t h c o l u m n s o p e r a t e d  points vary  7.1  systematically  transfer  demonstrates the  and PPM  profiles  rather  than  discussed  in Section  just  do  not  was  fall  °C,  small  to  on  The a  data  straight  implies that not  of m e a s u r i n g the the . t e r m i n a l value  Z.  v s c o 2  column. This  6.2.2, t h e  ±8  isothermally.  coefficient  importance  to  changes  and  sufficiently  shows a t y p i c a l p l o t o f Y  l i n e even f o r t h i s s h o r t o v e r a l l mass  temperature  f u l l - l e n g t h c o l u m n s were w i t h i n ±3  respectively.  Figure  The  used  of t h e  constant  the and  concentration conditions. enhancement  As  211  q o  o o  0.00  0.25  0.50  0.75  1.00  D i s t a n c ef r o mC o u lm nB o t o mm () F i g u r e 7.1: A t y p i c a l p l o t o f C 0 m o l e r a t i o i n t h e g a s p h a s e a s a f u n c t i o n o f h e i g h t i n t h e PPM c o l u m n , Run S 5 . P o i n t s d e n o t e e x p e r i m e n t a l d a t a a n d t h e s o l i d l i n e i n d i c a t e s the best f i t using a t h i r d order polynomial equation. (Experimental c o n d i t i o n s : L i q u i d f l o w r a t e = 13.5 m /m h r ; a i r f l o w r a t e = 14.8 m o l / m s; t e m p e r a t u r e = 293 K ; t o t a l p r e s s u r e = 101.3 k P a ; [ N a * ] = 1.20 k m o l / m ; [OH ] = 0.75 t o 0.56 k m o l / m ; C 0 c o n c e n t r a t i o n = 4.1 t o 2.0%.) 2  3  2  2  3  3  2  212  f a c t o r can column  change by  a s much  as a  each  e x p e r i m e n t a l run  with  t h e PPM  c o n c e n t r a t i o n m e a s u r e m e n t s were f i t t e d order polynomial equation.  The  the  0.99.  fits  g e n e r a l l y exceeded  differentiated analytically.  see E q u a t i o n  In  the  case of  The  The  by means o f a  third  p o l y n o m i a l s were  v a l u e s of R  t h e CC^-NaOH v  could also  v  then  were o b t a i n e d  r e s u l t s and G j  experimental  a v e r a g e , 5.5%  system, a l l  (also  i n Chapter  and  (maximum 12%)  on f i r s t  2.  calculated  n u m e r i c a l u n c e r t a i n t i e s . The  fundamental  which i s the product of R  be c a l c u l a t e d b a s e d  described previously  in  the  3.2.14).  p a r a m e t e r s a r e known and R ,  the  column,  correlation coefficients for  from the p r o d u c t of the d i f f e r e n t i a t e d  v  the  height.  For  a ,  2 over  f a c t o r of  and  principles  The d e v i a t i o n s R  v  due  values to  a  were,  as  between on  experimental  fundamental parameters  and  the and  required  t h e s e c a l c u l a t i o n s a r e t a k e n f r o m t h e same s o u r c e s a s t h e  computer  model ( a l s o see S e c t i o n 6.2.1).  a g r e e m e n t i s good a s CC^-NaOH  system  k i n e t i c s model s i m p l e and  shown by F i g u r e  has  been  i s well  irreversible,  studied  understood, which  The q u a l i t y o f  7.2  because:  extensively (ii)  the  (i) and  reaction  the the its is  improves the accuracy of the  ^ 1 <J  Figure  7.2: C o m p a r i s o n o f R v a l u e s o b t a i n e d e x p e r i m e n t a l l y f r o m model c o l u m n t e s t s a n d f r o m f i r s t p r i n c i p l e s . (Experimental c o n d i t i o n s : L i q u i d f l o w r a t e = 13.5 m /m h r ; a i r f l o w r a t e = 14.8 m o l / m s; t e m p e r a t u r e = 293 K; t o t a l p r e s s u r e = 101.3 k P a ; [ N a ] = 1.20 k m o l / m . ) v  3  2  2  +  3  214  enhancement and  a  v  f a c t o r c a l c u l a t i o n , and  values,  which are reported  been d e r i v e d f o r t h e CC^-NaOH  The R 7.3.  v  The  specific  v  diagram  lines  different R  - concentration  show  the  agree very  i s presented  relationship  the f l u i d calculated  f l u i d c o m p o s i t i o n s . As  values  , k  L  G  have  system.  the  r a t e and  a l l k  i n the l i t e r a t u r e ,  diagram  shows  absorption  continuous  ( i i i ) almost  well with  in  Figure  between  the  compositions.  The  values  c a n be s e e n ,  of  R  for  v  the  computed  the experimental  results,  showing t h a t i t i s p o s s i b l e t o d e s i g n packed a b s o r b e r s  with  chemical  that  the  r e a c t i o n based  fundamental  data  on f i r s t  principles provided  (mass t r a n s f e r c o e f f i c i e n t s ,  c h e m i c a l p r o p e r t i e s , e t c . ) a r e reliably  The R  v  be u s e d t o either this fluid  physico-  known.  v a l u e s o b t a i n e d from model column t e s t s can evaluate the i n t e g r a l  i n Equation  g r a p h i c a l o r n u m e r i c a l methods.  integration,  the R  compositions  or  d i a g r a m s s u c h a s shown 56 d a t a p o i n t s f r o m d a t a b a s e . The R  v  of gas and l i q u i d  v  In order t o  using perform  must be a v a i l a b l e a s a f u n c t i o n in  the  from  i n F i g u r e 7.3.  14 PPM  values  3.2.11  then  of  R -concentration v  In the present  c o l u m n r u n s were e n t e r e d corresponding  of  case, into  t o any d e s i r e d  c o n c e n t r a t i o n s were r e t r i e v e d  from  the  a  pair  215  F i g u r e 7.3: S p e c i f i c a b s o r p t i o n rate (R ) as a f u n c t i o n of C O 2 c o n c e n t r a t i o n i n the gas phase and OH" c o n c e n t r a t i o n . The p o i n t s and s o l i d l i n e s a r e obtained from experiments and t h e o r e t i c a l c a l c u l a t i o n s , r e s p e c t i v e l y . The dotted l i n e denotes t y p i c a l R values along the column f o r Run T2. (Experimental c o n d i t i o n s : L i q u i d flow r a t e = 13.5 m /m h r ; a i r flow rate = 14.8 mol/m s; temperature = 293 K; t o t a l pressure = 101.3 kPa; [ N a ] = 1.20 kmol/m .) v  v  3  2  2  +  3  216  data  base  which  is  method  and  which  to  the  thereby  the  (ii)  absorption  rate Figure  predicted  (solid  in  the  results  and  a  of  full-length  also  and  B r i t i s h  of  which  to  column.  for  is  excellent  predict  from values the  along  the  with  the  difference  always  the  was  seen,  hydroxide  The  model  factor  be  and  CO2  expected  are  can  values  v  conducted  less  validity  of  than the  because:  (i)  the  columns  were  the  concentration  shows  R  concentrations.  7.1.  and  experimental  used  runs  heights  be  As  fluid  of  support  could  T2.  the  Table  predicted  typical  significantly  variety  strong  lines  full-length  of  enhancement  7.4  Run  changes  in  effect  and  are  DFIN3D,  interpolation  University  shows  experimental  shown  the  3.2.11)  called  squares  the  7.3 for  rate  for  the  account.  model  column  agreement of  from  Figure  six  are  good  least  variations  of  actual  hydrodynamics  Equation  in  providing  The  package  Centre.  column  concentrations  and  weighted  available  line  results  full-length  same  is  interpolation  absorption  due  The  PPT.  a  full-length  specific  absorber  8%  on  dotted  the  between  an  Computing  The along  using  based  Columbia  the  by  on  the  fully  taken  agreement the  specific into between  integration  (points)  concentration  when  of the  profiles  217  Table  7 . 1 : A c t u a l and p r e d i c t e d h e i g h t s f o r t h e a b s o r p t i o n t o w e r r e m o v i n g CO2 from a i r by c o n t a c t w i t h an a q u e o u s NaOH solution.  ( E x p e r i m e n t a l c o n d i t i o n s : L i q u i d f l o w r a t e = 13.5 m^/m^ a i r f l o w r a t e = 14.8 mol/m^ s; t e m p e r a t u r e = 293 K; t o t a l p r e s s u r e = 101.3 kPa; [ N a ] = 1.20 kmol/m .) +  Run  #  [OH~]  Cone.  C0  2  (kmol/m )  3  Mass B a l  (% )  3  in  Cone.  hr;  Tower  Error  Actual (m)  out  in  out  (%)  8.90  2.30  +3.06  Height  Predicted  Error  (m)  (%)  3.25  3.01  7.38  T1  0.75  0.18  T2  1 .00  0.05  14.60  4.40  -1 .24  3.25  3.30  1 .54  T3  1 .02  0.01  18.20  7.75  -3.76  3.25  3.36  3.38  T4  0.80  0.10  1 .05  + 1 .54  4.35  4.40  1.15  T5  0.86  0.00  12.35  2.95  -0.37  4.35  4.01  7.82  T6  1 .03  0.07  12.50  1 .90  + 1.91  4.35  4.19  3.68  For  the d e t a i l s  9.10  of t h e f u l l - l e n g t h  column p r o f i l e s ,  see T a b l e  6.1.  218  0.0  2.0  1.0  3.0  Distance from Column Top (m) Figure  7.4:  A c t u a l ( p o i n t s ) and p r e d i c t e d ( s o l i d l i n e s ) of C0 a n d NaOH c o n c e n t r a t i o n s i n t h e f u l l - s c a l e a b s o r b e r f o r Run T 2 . ( E x p e r i m e n t a l conditions: L i q u i d f l o w r a t e = 13.5 m / m h r ; a i r f l o w r a t e = 14.8 m o l / m s ; t e m p e r a t u r e = 293 K ; t o t a l p r e s s u r e = 101.3 k P a ; [ N a ] = 1.20 k m o l / m . ) 2  3  2  2  +  5  219  7.2  V E R I F I C A T I O N USING THE  As  can  correspond given the  be  PPT  SHORT-CUT PROCEDURE  seen f r o m F i g u r e  to  the c o n c e n t r a t i o n s  gas  and  liquid  flow  a  large  column. Therefore, explained  in  circumstances.  The  changed,  with  short-cut  of  e x c h a n g e between t h e c o l u m n  and  ensure a d i a b a t i c c o n d i t i o n ,  the column  3/4"  fiber  glass.  concentrations  and  The  R  the  p e r f o r m e d u s i n g NaOH-C0  v  i s very  surroundings  values  thus  was  2  and  AMP-C0  2  of  necessary the  PPM as such  operation little  [54,  heat  1.05].  insulated  d e p e n d on t h e  t e m p e r a t u r e . The  v  under  adiabatic  w o u l d a l s o be more r e a l i s t i c s i n c e t h e r e  R-  procedure  practical  a  When  as a f u n c t i o n  experiments  approximation  for  the  i t is  w o u l d be  that  needed.  this,  t h e PPT  S e c t i o n 3.2.2  really  are  In doing  values  v  the column  constructed  number o f using  are  rates  f l u i d f l o w r a t e as w e l l .  to perform  only the R  along  s e t of o p e r a t i n g c o n d i t i o n s  c o n c e n t r a t i o n d i a g r a m must be the  7.3,  To with  fluid  verification  systems operated  was under  a v a r i e t y of f l u i d c o n c e n t r a t i o n s .  7.2.1  NaOH-C0  SYSTEM  2  Originally system  for  absorption  it  the of C 0  2  had  been  short-cut into highly  intended  t o use  verification. concentrated  the  C0 ~MEA 2  However, (2.0  - 2.5  the M)  220  NaOH  solutions  experiments  was  selected  showed  that  reaction characteristics  instead,  both  have  (see Chapter  since  exploratory  similar  absorption-  6 a n d F i g u r e 6 . 6 ) . The  r e a s o n s f o r f a v o r i n g t h e C02 NaOH s y s t e m were t h a t  i t takes  _  l e s s time and r e s o u r c e s t o r u n e x p e r i m e n t s and t h e  analysis  o f t h e - l i q u i d s a m p l e i s more d i r e c t a n d r e l i a b l e .  The r e s u l t s  of 4  sets of  r u n s a n d 16 s e c t i o n r u n s  experiments  (4  full-length  u s i n g t h e model c o l u m n ) a r e  shown  i n T a b l e 7.2. Due t o t h e f a c t t h a t h i g h l y c o n c e n t r a t e d  NaOH  s o l u t i o n s were u s e d  than  and h i g h  c o n v e r s i o n (up  t o more  90%) o c c u r r e d , t h e t e m p e r a t u r e  increases i n the  a b s o r b e r ranged from  42 °C. To v e r i f y  o f t h e PPT t o  14 up t o  by m a t c h i n g  ( a l s o see s e c t i o n  h e i g h t s a r e always  PPT p r e d i c t e d r e s u l t s  7%. F i g u r e s 7.5  from  predicted  t o 7.8  e x p e r i m e n t a l measurements  f o rthe  the f u l l - l e n g t h columns.  with  from t h e t o p o f  3 . 2 . 2 ) . As c a n be n o t e d  l e s s than  agreement between  under  t h e - f l u i d c o n c e n t r a t i o n s as w e l l  T a b l e 7.2, t h e d i f f e r e n c e s b e t w e e n t h e a c t u a l a n d  show good  ability  were p e r f o r m e d  a s t e m p e r a t u r e s s e c t i o n by s e c t i o n s t a r t i n g the absorber  the  design f u l l - l e n g t h absorbers operating  non-isothermal c o n d i t i o n s , experiments t h e PPM c o l u m n  full-length  concentration profile  also and along  221  Table  7.2:  V e r i f i c a t i o n r e s u l t s f o r t h e PPT s h o r t - c u t p r o c e d u r e u s i n g t h e NaOH-CC^ s y s t e m .  T7  T8  T9  T1 0  9.5  9.5  13.5  13.5  Gas f l o w r a t e (mol/m s)  14.8  14.8  14.8  14.8  [Na ] t o t a l (kmol/m )  2.0  2.5  2.0  2.0  Run #  Liquid (m /m 3  flow h)  2  rate  2  +  cone,  3  [OH ] c o n e . (kmol/m )  in out  2.00 0.09  2.50 0.18  2.00 0.37  1 .50 0.24  C0  in out  15.45 1 .25  18.60 1 .70  18.45 1 .00  15.20 1 .75  in out  14.5 37.0  14.0 42.0  15.0 35.0  15.0 30.0  -2.23  -5.69  + 1 .51  4.35  4.35  4.35  4.35  4.40  4.53  4.65  4.62  1.2  4. 1  6.9  6.2  3  2  cone.  (%) Liquid (°C)  temp.  Mass B a l a n c e Error (%) Actual (m)  •1 . 7 9  height  PPT p r e d i c t e d (m)  height  Error (%)  For d e t a i l s  of the column p r o f i l e s ,  see T a b l e  6.1.  222  However, t h e t e m p e r a t u r e m e a s u r e m e n t s p r e d i c t e d by short-cut procedure lower  using the  t o 7.12.  The r e a s o n  u n s a t u r a t e d a i r was u s e d water v a p o r i z a t i o n caused  the  reaction  as t h e  be l o w e r  than the  reduced temperatures r e s u l t e d specific  the  liquid  predicted absorber height w i t h 4.39  m  under  b e t w e e n t h e two  was  by  the  As a  some PPT  (50%  short-cut  i n l o w e r enhancement To  confirm the  temperature found t o  actual heights.  150%).  factors  effect  d e s c r i b e d i n Chapter  the normal  to  which  the  w i t h i n d u s t r i a l design approaches t o 2.5  result,  heat  by  be 4.52  condition.  The  For t h i s  was  3  °C.  The  m  compared difference  reason,  a r e up t o a b o u t  D e v i a t i o n s of  that u t i l i z e  of  6  7% i n  p r e d i c t i o n o f c o l u m n h e i g h t s a r e however v e r y s m a l l  1.5  that  f u n c t i o n of temperature,  i s a p p r o x i m a t e l y 3%.  g r e a t e r than the  be  by  the  PPT p r e d i c t e d h e i g h t s shown i n T a b l e 7.2  of  little  Since  absorption rates.  lower  gas.  actual values.  t e m p e r a t u r e , t h e computer model to  t h i s may  consumed  measured  r a t e i s an i n c r e a s i n g  for inert  o c c u r r e d and  temperature  procedure to  forced  were a  ( 2 t o 5 °C) t h a n t h e a c t u a l m e a s u r e m e n t s a s shown  F i g u r e s 7.9  and  model column  the  the 7% the  compared  safety  factor  223  0.0  2.0  Distance f r o m Column Top (m)  4.0  Figure 7.5: A c t u a l ( p o i n t s ) and PPT p r e d i c t e d values of C 0 ( s o l i d l i n e ) and NaOH (dotted l i n e ) c o n c e n t r a t i o n s i n the f u l l - s c a l e absorber f o r Run T7. Operating c o n d i t i o n s : a i r flow rate = 14.8 mol/m s; l i q u i d flow rate = 9.5 m /m h r ; C0 c o n c e n t r a t i o n = 1.25%(top) and 15.45%(bottom); [OH ] = 2.0(top) and 0.14(bottom) kmol/m . 2  2  3  2  3  2  224  0.0  2.0  Distance from Column Top (m)  4.0  F i g u r e 7.6: A c t u a l ( p o i n t s ) and PPT p r e d i c t e d v a l u e s of C 0 ( s o l i d l i n e ) and NaOH ( d o t t e d l i n e ) c o n c e n t r a t i o n s i n the f u l l - s c a l e absorber f o r Run T8. O p e r a t i n g c o n d i t i o n s : a i r f l o w r a t e = 14.8 mol/m s; l i q u i d f l o w r a t e = 9.5 m /m h r ; C 0 _ c o n c e n t r a t i o n = 1.7%(top) and 1 8 . 6 % ( b o t t o m ) ; [OH ] = 2 . 5 ( t o p ) and O.!8(bottom) kmol/m . 2  2  3  2  2  3  225  0.0  2.0  4.0  Distance f r o m Column Top (m) Figure  7.7: A c t u a l ( p o i n t s ) a n d PPT p r e d i c t e d v a l u e s o f C 0 ( s o l i d l i n e ) a n d NaOH ( d o t t e d l i n e ) concentrations i n the f u l l - s c a l e absorber f o r Run T9. O p e r a t i n g c o n d i t i o n s : a i r f l o w r a t e = 14.8 m o l / m s; l i q u i d f l o w r a t e = 13.5 m /m h r ; C 0 c o n c e n t r a t i o n =_1.0%(top) and l8.45%(bottom); [OH ] = 2 . 0 ( t o p ) a n d 0.37(bottom) kmol/m . 2  2  3  2  3  2  226  o  O  6 o o o o  2.0  0.0 Figure  q d  4.0  Distance from Column Top (m) 7.8  A c t u a l ( p o i n t s ) and PPT p r e d i c t e d v a l u e s of C 0 ( s o l i d l i n e ) and NaOH ( d o t t e d l i n e ) c o n c e n t r a t i o n s i n the f u l l - s c a l e absorber f o r Run T10. O p e r a t i n g c o n d i t i o n s : a i r f l o w r a t e = 14.8 m o l / m s ; l i q u i d f l o w r a t e = 13.5 m / m h r ; C0 c o n c e n t r a t i o n = 1.75%(top) and 1 5 . 2 % ( b o t t o m ) ; [OH ] = l . 5 ( t o p ) and 0 . 2 4 ( b o t t o m ) kmol/m . 2  2  2  3  3  2  227  0.0  F i g u r e 7.9:  2.0  4.0  Distance f r o m Column Top (m) Column t e m p e r a t u r e m e a s u r e d f r o m t h e f u l l - l e n g t h column ( s o l i d c i r c l e s ) and PPM c o l u m n (open s q u a r e s ) f o r Run T7. Operating conditions: a i r f l o w r a t e = 14.8 m o l / m s; l i q u i d f l o w r a t e = 9.5 m /m h r ; C 0 c o n c e n t r a t i o n = 1.25% ( t o p ) and 1 5 . 4 5 % ( b o t t o m ) ; [OH~] = 2 . 0 ( t o p ) and 0.14(bottom) kmol/m . 2  3  2  2  3  228  Figure  7.10:  Column t e m p e r a t u r e m e a s u r e d f r o m t h e f u l l l e n g t h c o l u m n ( s o l i d c i r c l e s ) and PPM c o l u m n (open s q u a r e s ) f o r Run T8. O p e r a t i n g c o n d i t i o n s : a i r f l o w r a t e = 14.8 m o l / m s; l i q u i d f l o w r a t e = 9.5 m /m h r ; COo c o n c e n t r a t i o n = 1 . 7 % ( t o p ) and 1 8 . 6 % f b o t t o m ) ; [OH ] = 2 . 5 ( t o p ) and 0 . ! 8 ( b o t t o m ) k m o l / m . 2  3  2  3  229  Figure  7.11:  Column t e m p e r a t u r e m e a s u r e d f r o m t h e f u l l l e n g t h c o l u m n ( s o l i d c i r c l e s ) and PPM c o l u m n (open s q u a r e s ) f o r Run T9. O p e r a t i n g c o n d i t i o n s : a i r f l o w r a t e = 14.8 m o l / m s; l i q u i d f l o w r a t e = 13.5 m /m h r ; CO? c o n c e n t r a t i o n = 1.0%(top) and 18.45%(bottom); [0H~] = 2 . 0 ( t o p ) a n d 0 . 3 7 ( b o t t o m ) k m o l / m . 2  3  2  3  230  q d co  Figure  7.12:  Column t e m p e r a t u r e m e a s u r e d f r o m t h e f u l l l e n g t h column ( s o l i d c i r c l e s ) and PPM c o l u m n (open s q u a r e s ) f o r Run T10. O p e r a t i n g c o n d i t i o n s : a i r f l o w r a t e = 14.8 m o l / m s; l i q u i d f l o w r a t e = 13.5 m /m h r ; C 0 c o n c e n t r a t i o n = 1 . 7 5 % ( t o p ) and 1 5 . 2 % ( b o t t o m ) ; [OH ] = 1 . 5 ( t o p ) and 0 . 2 4 ( b o t t o m ) k m o l / m . 2  3  2  2  3  231  7.2.2 CO -AMP SYSTEM 2  Further absorption  verification  o f C O 2 by 2  procedure f o r t h i s  o f t h e PPT i s p e r f o r m e d u s i n g M AMP  system i s the  NaOH-C02 system d e s c r i b e d before  GENERAL  i n the previous  no c o m p r e h e n s i v e  regarding  i t i s necessary  experimental  columns u s i n g  are presented,  the  solution  However, t o make  OBSERVATIONS  temperature and c o m p o s i t i o n absorber  section.  observations.  Since reported  verification  same a s t h a t u s e d f o r t h e  dealing with the v e r i f i c a t i o n  some g e n e r a l  Since  s o l u t i o n s . The  experimental  t h e CO2-AMP  profiles  along  for the f i r s t data  data  have  the  time,  p r o f i l e along  7.13 a n d  absorption  7.14. I t  r a t e u s i n g MEA  full-length  i n Table  f o r CO2 absorption  t h e column h e i g h t i s interesting  may be due  largely  i n Figure to the  C0 -AMP s y s t e m i s s l o w e r  to  i s much h i g h e r  l o a d i n g i s below a p p r o x i m a t e l y  o f amine a s shown  2  the  7.3.  into  o f MEA i n t h e same p a c k e d c o l u m n a r e a v a i l a b l e ,  concentration  the  been  system,  c o l u m n p e r f o r m a n c e i s t h e r e f o r e c o m p a r e d by p l o t t i n g  Figures  the  the  the CO2  a s shown see t h a t  t h a n f o r AMP  in the when  0.5 m o l e s o f C O 2 p e r mole  7.13 (Runs fact  the  T21 a n d T 2 7 ) .  that the  reaction rate  t h a n t h a t o f C0 "MEA 2  This  [72,  145].  of  232  T a b l e 7.3: E x p e r i m e n t a l r e s u l t s f o r t h e C02 AMP  system.  -  Run  (#)  T23  A i r Flow Rate (mol/m s)  T24  T25  T26  14.,8  14.,8  14.,8  14.,8  Rate  9.,5  9..5  9..5  9.,5  Absorbent Feed Cone, ( k m o l / m )  2..0  2..0  2..0  2..0  8,.90 10,.50 12,.20 13,.85 15,.45  10..10 1 1 .80 . 13,.40 15,.15 16,.70 17,.80 18,.90  7..70 9,.55 1 1 .55 , 13,.70 15,.70 17,.35 18,.65  51 ,.8  63,.6  2  L i q u i d Flow (m /m h) 3  2  3  Gas C 0 Conc.(%) ©height f r o m t o p : 0.00 m 6..80 1 .05 m 8..60 2.15m 10..70 3.25 m 13..30 4.35 m 15..25 5.45 m 6.55 m 2  C0  2  removal  (%)  »  >  <  —,>  60,.4  46,.6  C0 l o a d i n g ( m o l C 0 / m o l AMP) ©height f r o m t o p : 0. 147 0.00 m 0.000 1 .05 m 0.202 0.058 2.15 m 0.131 0.258 0.212 0.317 3.25 m 4.35 m 0.285 0.387 5.45 m • • 6.55 m • • 2  Mass b a l a n c e (%)  2  0.1 52 0.215 0.277 0.341 0.396 0.442 0.464  0.022 0.083 0. 149 0.223 0.303 0.358 0.411  error  L i q . Temp (°C) ©height f r o m t o p : 0.00 m 1 .05 m 2.15 m 3.25 m 4.35 m 5.45 m 6.55 m  -4.24  +1.52  -7.53  -4.31  15.0 16.0 17.0 19.0 23.0  15.0 17.0 19.0 21 .0 21 .0  15.0 17.0 18.0 21 .0 23.0 24.5 24.5  15.0 17.0 20.0 23.0 26.5 28.0 29.0  •  •  •  •  N o t e : The v a l u e s i n ( ) a r e c a l c u l a t e d  f r o m mass b a l a n c e .  Table 7.3(con't): E x p e r i m e n t a l r e s u l t s f o r t h e CO2-AMP s y s t e m . Run  (#)  T27  A i r Flow Rate (mol/m s)  11. 1  2  L i q u i d Flow <m /m h)  T28 14.8  T29  T30  14.8  1 1 .1  13.5  13. 5  Rate  9. 5  9.5  A b s o r b e n t Feed Cone, (kmol/m )  2. 0  2.0  Gas C 0 C o n e . ( % ) ©height f r o m t o p : 0.00 m 1.05m 2.15m 3.25 m 4.35 m 5.45 m 6.55 m  4. 25 6. 15 8. 40 20 11 . 14. 1 5 16. 95 19. 00  13.25 14.55 15.65 16.75 17.75 18.40 19.15  5.95 7.65 9.50 1 1 .70 1 4.70 17.05 19.00  2. 65 4. 00 6. 00 8. 70 12. 25 15. 85 19. 00  C0  81 . 1  35.5  73.0  88. 4  3  2  2.0  2. 0  3  2  2  removal  (%)  C0 l o a d i n g ( m o l C 0 / m o l AMP) ©height f r o m t o p : 0.00 m 0.021 0. 371 1.05 m 0.058 0. 417 2.15m 0.113 0. 449 3.25 m 0.174 0. 484 4.35 m 0.254 0. 536 5.45 m 0.323 0. 550 6.55 m 0.383 0. 583  0. 038 ( 0 . 079) ( 0 . 1 19) ( 0 . 173) ( 0 . 251 ) ( 0 . 316) 0. 385  Mass b a l a n c e e r r o r (%) -9.31  + 3.61  2  L i q . Temp (°C) ©height f r o m t o p : 0.00 m 1.05 m 2.15m 3.25 m 4.35 m 5.45 m 6.55 m  2  15.0 16.5 19.0 21.0 24.5 26.0 28.0  9. 67  15.0 16.0 18.0 19.0 20.0 21 .0 21 .0  14.0 16.0 18.0 20.0 22.5 24.0 26.0  N o t e : The v a l u e s i n ( ) a r e c a l c u l a t e d  0. 029 0. 045 0. 078 0. 1 22 0. 182 0. 233 0. 300  -11 . 60  15.0 16.0 17.0 19.0 21 .0 23.0 25.0 f r o m mass b a l a n c e .  234  6.0  0.0  Figure  C0  2  Cone.  12.0  18.0  (%)  7.13: Column p e r f o r m a n c e a t low l o a d i n g . MEA (Run T21 - open s q u a r e s ) v s AMP (Run T27 - s o l i d c i r c l e s ) . O p e r a t i n g c o n d i t i o n s : gas f l o w r a t e = 11.1 mol/m s; l i q u i d f l o w r a t e = 9.5 m /m h r ; t o t a l amine c o n c e n t r a t i o n = 2.0 k m o l / m ; i n l e t g a s C 0 c o n c e n t r a t i o n = 19.0%; i n l e t C 0 l o a d i n g = 0.02 m o l e s o f C 0 / mole o f a m i n e . 2  3  2  2  2  2  2  235  Figure  7.14: Column p e r f o r m a n c e a t h i g h l o a d i n g . AMP (Run T28 - s o l i d c i r c l e s ) v s MEA (Run T18 - open s q u a r e s ) . O p e r a t i n g c o n d i t i o n s : gas flow r a t e = 14.8 mol/m s; l i q u i d f l o w r a t e = 9.5 m /m h r ; t o t a l amine c o n c e n t r a t i o n = 2.0 kmol/m ; i n l e t gas C 0 c o n c e n t r a t i o n = 19.15%; o u t l e t C 0 l o a d i n g = 0.583 m o l e s o f C 0 / mole o f amine. The l i n e s r e p r e s e n t smoothed experimental values. 2  3  2  2  2  2  2  236  On t h e o t h e r h a n d , t h e o p p o s i t e i s t r u e a n d a c r o s s - o v e r can  be s e e n when  m o l e s o f CO2  t h e l o a d i n g e x c e e d s 0.5  per  m o l e o f amine a s shown i n F i g u r e 7.14 (Run T18 v s T 2 8 ) . The reason  for this  i s t h a t when t h e l o a d i n g i s l a r g e r  than  0.5  m o l e s o f CO2 p e r mole o f a m i n e , t h e f r e e a m i n e c o n c e n t r a t i o n i n MEA s o l u t i o n s  is. v i r t u a l l y  nil.  a m i n e c o n c e n t r a t i o n i n AMP s o l u t i o n s is approximately half  of  f r e e AMP  contrast, the  f o r t h e same  causes  instability  the carbamate i s e a s i l y  lines  AMP  reversed  to  8 runs,  a  tendency  problems although  to  f l o o d d i d occur  the absorber  by  t h e foaming  f u r t h e r aggravated  nature of  by  be  from  the  was a l s o n o t i c e d t h a t f l o o d i n g  was  than  Antifoam  s p i t e of t h e  matter  i n the regenerator.  The  a d d i t i o n o f a few ppm  of  B ( t r a d e name)  by Dow C o r n i n g C o r p . a n d m a r k e t e d Ont. I n  i s believed to  the solution,  particulate  c o m p l e t e l y by  the a n t i f o a m i n g agent,  operated  was  the absorber  was r e d u c e d  and  foaming  which  fine  p a c k i n g and t h e a i r . I t more s e r i o u s i n  problem  approximately  due- t o  was d e s i g n e d  b e l o w t h e f l o o d i n g v e l o c i t y . The  from  data.  A f t e r t h e AMP s o l u t i o n h a d been u s e d f o r  Toronto,  f o r the  i n F i g u r e s 7.13 a n d 7.14 a r e d r a w n  smoothed v a l u e s of t h e c o r r e s p o n d i n g  problem  due  ( a l s o s e e S e c t i o n s 2.2 a n d 4 . 3 ) . I t - s h o u l d be n o t e d  that the s o l i d  caused  free  situation  t h e t o t a l amine c o n c e n t r a t i o n  to t h e hindered e f f e c t which c a r b a m a t e . As a r e s u l t ,  By  manufactured  i n Canada by BDH I n c . o f  a d d i t i o n of the  antifoaming  237  agent,  the  problem  r e g e n e r a t i o n . The  would  flooding  e v a p o r a t i o n and/or  reappear  after  r e a p p e a r a n c e may  degradation  of  the  be  solution due  antifoaming  c a u s e d by t h e h i g h t e m p e r a t u r e i n t h e r e b o i l e r .  were t h e r e f o r e t y p i c a l l y  the s o l u t i o n  a f t e r each  regeneration run.  there i s  significant  e f f e c t of  o v e r a l l a b s o r p t i o n , comparison i n F i g u r e 7.15  . The  a n t i f o a m a g e n t . On with antifoam  a d d e d and  had  were p e r f o r m e d u n d e r  shows t h a t t h e C 0 virtually  2  antifoam  f o r r u n S70 S94  was  been u s e d  f o r more  to that  on  the shown  contained  hand, run  no  conducted than  t h e same c o n d i t i o n s . F i g u r e  concentration, p r o f i l e  ppm  To e n s u r e  a b s o r p t i o n and r e g e n e r a t i o n e x p e r i m e n t s . B o t h r u n s , S70 S94,  agent  added  r u n s were p e r f o r m e d a s  s o l u t i o n used the other  the  the  5 t o 10  of t h e a n t i f o a m i n g agent  no  to  40 and 7.15  from both runs  are  p r e d i c t e d by  the  identical.  COMPARISON RESULTS  The  results  of 6  e x p e r i m e n t a l runs  s h o r t - c u t p r o c e d u r e u s i n g 24 PPM i n T a b l e 7.4.  As c a n be s e e n  was  The  obtained.  difference  p r e d i c t e d r e s u l t s was  column  runs are  f r o m T a b l e 7.4, between  always l e s s than  summarized  good agreement  the a c t u a l  and  12%. S l i g h t l y  a c c u r a t e r e s u l t s were o b t a i n e d w i t h t h e C0 -AMP s y s t e m 2  PPT less than  238  O  O  0.00  0.25  0.50  0.75  1.00  D i s t a n c ef r o m C o u lm nB o t o mm () Figure  7.15:  c o n c e n t r a t i o n p r o f i l e o f Run #S70 without a n t i f o a m i n g a g e n t (open c i r c l e s ) a n d Run #S94 with a n t i f o a m i n g agent ( s t a r s ) . O p e r a t i n g c o n d i t i o n s : g a s f l o w r a t e = 1 4 . 8 m o l / m s; l i q u i d f l o w r a t e = 9.5 m /m h r ; t o t a l a m i n e c o n c e n t r a t i o n = 2.0 k m o l / m .  CO2  2  3  2  2  239  Table  Run  #  Liquid  flow  (m /m  h)  3  Gas  7.4:  2  flow  (mol/m Total  2  V e r i f i c a t i o n r e s u l t s f o r t h e PPT s h o r t - c u t p r o c e d u r e u s i n g the AMP-CO2 s y s t e m .  T23  T24  T25  T26  T27  T30  9.5  9.5  9.5  9.5  9.5  13.5  14.8  14.8  14.8  14.8  11.1  11.1  rate  rate s)  cone,  of  AMP ( k m o l / m ) C0 loading in (mol C 0 / out mol C02)  2.0 0.000 0.285  2.0 0.147 0.387  2.0 0.152 0.464  2.0 0.022 0.411  2.0 0.021 0.383  2.0 0.29 0.300  C0 (%)  in out  15.25 6.80  15.45 8.90  18.90 10.10  18.65 7.70  19.00 4.25  19.00 2.65  in out  15.0 23.0  15.0 21.0  15.0 24.0  15.0 29.0  15.0 28.0  15.0 25.0  -4.24  +1.52  -7.53  -4.31  -9.31  -11.6  4.35  4.35  6.55  6.55  6.55  6.55  4.85  4.75  6.37  6.15  6.68  6.88  2.0  5.0  3  2  2  2  cone.  Liquid (°C) Mass  temp,  Balance  Error  (%)  Actual  height  (m) PPT  predicted  height  (m)  Error (%) F o r more d e t a i l s  11.5 9.0 2.7 on t h e column p r o f i l e s ,  6.1 see T a b l e  7.3.  240  the fact  C02 NaOH s y s t e m . The r e a s o n f o r t h i s may be due t o t h e -  that  the a n a l y s i s  of l i q u i d  system i s i n d i r e c t and t h e r e f o r e the  latter.  For a given  accuracy of composition 2 % a s compared w i t h solution be  larger  by  in predicting  than that  the  sample s i z e and c o n c e n t r a t i o n ,  the  a n a l y s i s of Na  fluid  the values  height  2.5 (50 t o 1 5 0 % ) ,  the in  i n the of R  AMP  could  v  uncertainty  t h i s case  allows  ±  is with  f o r safety  t h e 12 % a c c u r a c y  for  good.  a l s o show good a g r e e m e n t  between  a n d PPT r e s u l t s f o r t h e c o l u m n p r o f i l e s . I t p r e c i s e p r e d i c t i o n of the  overall  r a t e i n , o r t h e performance o f , t h e column  AMP-CO2 s y s t e m b a s e d on f i r s t  impossible  loading  p r a c t i c e which t y p i c a l l y  be n o t e d t h a t t h e  absorption  2  i s within  -  -  7.16 t o 7.27  experimental  and OH  +  composition,  t h e column  PPT p r e d i c t i o n s i s v e r y  should  the  for  f o r t h e C02 NaOH s y s t e m . By c o m p a r i s o n  f a c t o r s o f 1.5 t o  Figures  former  than that  ± 3.3 % f o r t h e C 0  the  i n d u s t r i a l design  the  less precise  ( a l s o see Appendix A ) . S i n c e  affected  involved  samples f o r t h e  because t h e  r e a c t i o n mechanism  w e l l understood and i n s u f f i c i e n t i t s physico-chemical  principles i s  practically  involved  fundamental data  p r o p e r t i e s h a v e been  using  reported.  i s not regarding  d  0.0  Figure  1  1  2.0  4.0  Distance from Column Top (m)  L_ 6.0  7.16: A c t u a l ( p o i n t s ) and p r e d i c t e d v a l u e s o f C 0 ( s o l i d l i n e ) and l i q u i d l o a d i n g ( d o t t e d l i n e ) i n t h e f u l l - s c a l e a b s o r b e r f o r Run T23. O p e r a t i n g c o n d i t i o n s : gas f l o w r a t e = 14.8 mol/m s; l i q u i d f l o w r a t e = 9.5 m /m h r ; t o t a l AMP c o n c e n t r a t i o n - 2.0 kmol/m ; i n l e t gas C 0 c o n c e n t r a t i o n = 15.5%; i n l e t l i q u i d l o a d i n g = 0 mol C 0 / m o l AMP. 2  2  3  2  2  2  2  242  F i g u r e 7.17: A c t u a l ( p o i n t s ) and p r e d i c t e d v a l u e s o f C O 2 ( s o l i d l i n e ) and l i q u i d l o a d i n g ( d o t t e d l i n e ) i n t h e f u l l - s c a l e a b s o r b e r f o r Run T 2 4 . O p e r a t i n g c o n d i t i o n s : gas f l o w r a t e - 14.8 mol/m s; l i q u i d f l o w r a t e = 9 . 5 m /m h r ; t o t a l AMP c o n c e n t r a t i o n = 2 . 0 kmol/m ; i n l e t gas CO2 c o n c e n t r a t i o n = 1 5 . 5 % . ; i n l e t l i q u i d l o a d i n g = 0 . 1 4 7 mol C 0 / m o l AMP. 2  3  2  2  2  243  0.0  2.0  4.0  6.0  Distance from Column Top (m) Figure  7 . 1 8 : A c t u a l ( p o i n t s ) and p r e d i c t e d v a l u e s o f C 0 ( s o l i d l i n e ) and l i q u i d l o a d i n g ( d o t t e d l i n e ) i n t h e f u l l - s c a l e a b s o r b e r f o r Run T 2 5 . O p e r a t i n g c o n d i t i o n s : gas f l o w r a t e = 1 4 . 8 mol/m s; l i q u i d f l o w r a t e = 9 . 5 m /m h r ; t o t a l AMP c o n c e n t r a t i o n = 2 . 0 kmol/m ; i n l e t gas C 0 c o n c e n t r a t i o n = 1 8 . 9 % ; i n l e t l i q u i d l o a d i n g = 0 . 1 5 2 mol C 0 / m o l AMP. 2  2  3  2  2  2  2  244  0.0  2.0  4.0  6.0  Distance from Column Top (m) Figure  7.19:  A c t u a l ( p o i n t s ) and p r e d i c t e d v a l u e s of C O 2 ( s o l i d l i n e ) and l i q u i d l o a d i n g ( d o t t e d l i n e ) i n the f u l l - s c a l e a b s o r b e r f o r Run T 2 6 . O p e r a t i n g c o n d i t i o n s : gas flow r a t e = 14.8 " m o l / m s ; l i q u i d flow r a t e = 9.5 m / m h r ; t o t a l AMP c o n c e n t r a t i o n = 2.0 k m o l / m ; i n l e t gas C 0 c o n c e n t r a t i o n = 18.65%; i n l e t l i q u i d l o a d i n g = 0.022 mol C 0 / m o l AMP. 2  3  2  2  2  2  245  Figure  7.20:  A c t u a l ( p o i n t s ) and p r e d i c t e d v a l u e s of C 0 ( s o l i d l i n e ) and l i q u i d l o a d i n g ( d o t t e d l i n e ) i n the f u l l - s c a l e a b s o r b e r f o r Run T27. O p e r a t i n g c o n d i t i o n s : gas f l o w r a t e = 11.1 mol/m s; l i q u i d f l o w r a t e = 9.5 m /m h r ; t o t a l AMP c o n c e n t r a t i o n — 2.0 kmol/m ; i n l e t gas C 0 c o n c e n t r a t i o n = 19.0%; i n l e t l i q u i d l o a d i n g = 0.021 mol C 0 / m o l AMP. 2  2  3  2  2  2  2  246  Distance from Column Top (m) Figure  7.21: A c t u a l ( p o i n t s ) and p r e d i c t e d v a l u e s o f C 0 ( s o l i d l i n e ) and l i q u i d l o a d i n g ( d o t t e d l i n e ) i n t h e f u l l - s c a l e a b s o r b e r f o r Run T30. O p e r a t i n g c o n d i t i o n s : gas f l o w r a t e = 11.1 mol/m s; l i q u i d f l o w r a t e = 13.5 m /m h r ; t o t a l AMP c o n c e n t r a t i o n = 2.0 kmol/m ; i n l e t gas C 0 c o n c e n t r a t i o n = 19.0%; i n l e t l i q u i d l o a d i n g = 0.29 mol C 0 / m o l A M P . 2  2  3  2  2  2  2  o CM CO  •  o o  CO  o — :  1 o d CO CM  i 0.0  2.0  i 6.0  4.0  Distance from Column Top (m)  F i g u r e 7 . 2 2 : Column t e m p e r a t u r e measured from t h e f u l l l e n g t h column ( s o l i d c i r c l e s ) and PPM column (open s q u a r e s ) f o r Run T 2 3 . O p e r a t i n g c o n d i t i o n s : gas f l o w r a t e = 14.8 mol/m s; l i q u i d f l o w r a t e = 9 . 5 m /m h r ; t o t a l AMP c o n c e n t r a t i o n = 2 . 0 kmol/m ; i n l e t gas C 0 c o n c e n t r a t i o n = 15.5%; i n l e t l i q u i d l o a d i n g mol C 0 / m o l AMP. 2  3  2  2  2  2  248  q d  CM CO  ft  o o  CO  O O  o co  CM  0.0  Figure  2.0  4.0  6.0  Distance from Column Top (m)  7.23: Column t e m p e r a t u r e m e a s u r e d f r o m t h e f u l l l e n g t h c o l u m n ( s o l i d c i r c l e s ) a n d PPM c o l u m n (open s q u a r e s ) f o r Run T24. O p e r a t i n g c o n d i t i o n s : g a s f l o w r a t e = 1 4 . 8 m o l / m s; l i q u i d f l o w r a t e = 9.5 m /m h r ; t o t a l AMP c o n c e n t r a t i o n = 2.0 k m o l / m ; i n l e t g a s C 0 c o n c e n t r a t i o n = 15.5%; i n l e t l i q u i d l o a d i n g = 0.147 m o l C 0 / m o l AMP. 2  3  2  2  2  2  249  o cv CO  PH  o o CO  o d CO  0.0  2.0  4.0  6.0  Distance f r o m Column Top (m) Figure  7.24: Column t e m p e r a t u r e m e a s u r e d f r o m t h e f u l l l e n g t h c o l u m n ( s o l i d c i r c l e s ) a n d PPM column(open s q u a r e s ) f o r Run T 2 5 . O p e r a t i n g c o n d i t i o n s : g a s f l o w r a t e = 14.8 m o l / m s; l i q u i d f l o w r a t e = 9.5 m /m h r ; t o t a l AMP c o n c e n t r a t i o n = 2.0 k m o l / m ; i n l e t g a s C 0 c o n c e n t r a t i o n ^ 18.9%; i n l e t l i q u i d l o a d i n g = 0.152 mol C 0 / m o l AMP. 2  3  2  2  2  2  o d  CM CO  ft  d o  I -  •  •  •  & m  m*"*'  O  d  03 CM  0.0  2.0  4.0  Distance f r o m Column Top (m)  6.0  F i g u r e 7.25: Column t e m p e r a t u r e m e a s u r e d f r o m t h e f u l l l e n g t h c o l u m n ( s o l i d c i r c l e s ) a n d PPM column, (open s q u a r e s ) f o r Run T26. O p e r a t i n g c o n d i t i o n s : g a s f l o w r a t e = 14.8 m o l / m s; l i q u i d f l o w r a t e = 9.5 m /m h r ; t o t a l AMP c o n c e n t r a t i o n = 2.0 k m o l / m ; i n l e t g a s C O o c o n c e n t r a t i o n = 18.65%; i n l e t l i q u i d l o a d i n g 0.022 mol C 0 / m o l AMP 2  3  2  2  2  251  0.0  2.0  4.0  6.0  D i s t a n c e f r o m C o l u m n Top  (m)  F i g u r e 7.26: Column t e m p e r a t u r e measured from t h e f u l l l e n g t h column ( s o l i d c i r c l e s ) and PPM column" (open s q u a r e s ) f o r Run T27. O p e r a t i n g c o n d i t i o n s : gas f l o w r a t e =11.1 mol/m s; l i q u i d f l o w r a t e = 9.5 m /m h r ; t o t a l AMP c o n c e n t r a t i o n = 2.0 kmol/m ; i n l e t gas C 0 c o n c e n t r a t i o n = 19.0%; i n l e t l i q u i d l o a d i n g = 0.021 mol C 0 / m o l AMP. 2  3  2  2  2  2  252  2.0  0.0  Figure  4.0  Distance from Column Top (m) 7.27  6.0  Column t e m p e r a t u r e m e a s u r e d f r o m t h e f u l l l e n g t h c o l u m n ( s o l i d c i r c l e s ) and PPM c o l u m n (open s q u a r e s ) f o r R u n T 3 0 . O p e r a t i n g c o n d i t i o n s : g a s f l o w r a t e = 11.1 m o l / m s; l i q u i d f l o w r a t e = 13.5 m /m h r ; t o t a l AMP c o n c e n t r a t i o n = 2.0 k m o l / m ; i n l e t g a s C 0 c o n c e n t r a t i o n = 19.0%; i n l e t l i q u i d l o a d i n g = 0.29 mol C 0 / m o l AMP. 2  3  2  2  2  2  253  7.3 DISCUSSION  OF THE V E R I F I C A T I O N RESULTS  The v a l i d i t y t e s t e d under distinct  of  the  a variety  systems: the  a n d t h e CO2-AMP  of  PPT d e s i g n  procedure  has  been  operating conditions  with  two  C02 NaOH s y s t e m w h i c h  i swell  -  s y s t e m w h i c h i s new. As c a n  T a b l e s 7.1-7.2 a n d 7.4,  known  be s e e n  from  t h e maximum d i f f e r e n c e b e t w e e n  the  a c t u a l a n d p r e d i c t e d h e i g h t s i s a l w a y s l e s s t h a n ± 12 % f o r b o t h s y s t e m s . From t h e s e r e s u l t s , the  i t c a n be c o n c l u d e d  PPT d e s i g n p r o c e d u r e p r o p o s e d  that  i n Chapter 3 i s sound.  It  must be n o t e d t h a t no a s s u m p t i o n h a s been made r e g a r d i n g t h e reaction applied  k i n e t i c s and mechanism. to a l l  were s u g g e s t e d  T h e r e f o r e , t h e PPT c a n  r e a c t i o n r e g i m e s shown by  Levenspiel  i n F i g u r e 2.2  flow i n packings.  i n f l u e n c e of the hydrodynamics rate  i s fully  taken i n t o account  Very recently  (May  1990),  r e p o r t e d a s t u d y on t h e r e a c t i o n  on  the s p e c i f i c  and  +  2 RNH  2  =  RNHCOO"  the  absorption  i n t h e PPT p r o c e d u r e . "  Bosch e t  a l . [120] have  k i n e t i c s o f CO2 i n  c o n s i s t s o f two p a r a l l e l a n d h i g h l y r e v e r s i b l e  2  no  transfer  T h i s means t h a t  AMP s o l u t i o n . They h a v e s u g g e s t e d t h a t t h e o v e r a l l  C0  which  [30, 3 1 ] . Furthermore,  a s s u m p t i o n s were made r e g a r d i n g t h e g a s - l i q u i d mass mechanism and f l u i d  be  +  RNH  + 3  aqueous reaction  reactions:  (g)  254  OH"  CO  The  hydroxyl  If  (h)  i o n i s d e r i v e d from  HoO  RNH-  HCO-  =  OH"  RNH-  =  t h i s hypothesis  AMP:  i s indeed  (i)  c o r r e c t , the e v a l u a t i o n of  t h e enhancement f a c t o r w o u l d be v e r y c o m p l i c a t e d . all,  finding  solutions  of p a r t i a l  which represent simultaneous chemical  reaction  Secondly,  the  both  in  as  p a r a m e t e r s must be mind t h a t these  well  differential  liquid  as  precisely  phase  is  reaction rate a l l  other  known.  and  unavoidable. constants  of  physico-chemical  I t should  parameters normally c o u l d  of  equations  d i f f u s i o n a l mass t r a n s f e r  e q u i l i b r i u m and  reactions  directly.  the  First  not  be be  kept  in  measured  I n d i r e c t methods, w h i c h a r e u s u a l l y a p p l i e d , would  i n c r e a s e the u n c e r t a i n t y i n parameter e s t i m a t i o n .  By a p p l y i n g t h e PPT system or  similar  method f o r c o l u m n d e s i g n u s i n g  systems,  the  above-mentioned  this  problems  w o u l d be e l i m i n a t e d .  To R  v  evaluate the u n c e r t a i n t i e s ( e r r o r s ) a s s o c i a t e d  determination  based  on  the  theoretical  with  calculations,  255  l a b o r a t o r y models and a n a l y s i s of the made. The  the P i l o t  type suggested  details  of  Plant  T e c h n i q u e , an  by M i c k l y  this error  error  et el.[144]  analysis  are  was  given  in  A p p e n d i x B a n d t h e r e s u l t s a r e s u m m a r i z e d i n T a b l e B.2.  As  c a n be  associated  with  calculations, Technique  the  R  v  determination  laboratory  are  in  r e s p e c t i v e l y . The obtained  from  the  R  v  the  As  and of  flow  Pilot  40%  Plant  and  with  R  20%,  v  values  the  largest  interfacial  with  their  in  area  r a t e and c o m p o s i t i o n  uncertainty  the  2,  the  Chapter  estimation  are, in  the  of  on t h e m e a s u r e m e n t s o f p r o f i l e s . The  quantities could  using  the  and  o f ±25%. By c o n t r a s t , t h e a c c u r a c y  measurement o f t h e s e two minimum  95%,  theoretical  calculation i s  d e t e r m i n e d by t h e PPT d e p e n d s o n l y fluid  the  associated  mentioned  associated  i n the order  b a s e d on  errors  o f many p a r a m e t e r s i n c l u d i n g  coefficients,  factor.  uncertainties general,  order  the t h e o r e t i c a l  transfer  enhancement  models  uncertainty  since they are a f u n c t i o n mass  B-; t h e potential  seen from Appendix  precise  be a c h i e v e d  currently  with  available  instruments.  I f we illustrate values  use the  the  operating  effect  on t h e h e i g h t  conditions  of u n c e r t a i n t y  of  Run  associated  T9 with  p r e d i c t i o n , t h e r e s u l t s c a n be s e e n  to R  v  in  256  T a b l e 7.5. The p r e d i c t e d  height  m when t h e e r r o r r e l a t e d t o R  v  i s v a r i e d f r o m 4.65 t o i s increased  t o about  T a b l e 7.5 a l s o shows t h e r a t i o o f t h e h e i g h t a given  uncertainty  r a t i o can required  t o t h a t under  be c o n s i d e r e d in  order  as a  to  can a  be s e e n , t h e d e s i g n  f a c t o r o f 1.2  with  normal c o n d i t i o n s .  This  minimum s a f e t y  avoid  the  factor,  designed  by c o m p a r i s o n w i t h  t o 2.5 i s commonly a p p l i e d gas  1.4 f o r t h e  that a safety  only  approach.  1.5  practice for  absorbers with chemical reaction. I t i s also i n t e r e s t i n g  sizing  packed  absorbers according noted that operations place the  As  laboratory  f a c t o r of  i n i n d u s t r i a l design  t o know t h a t a s a f e t y f a c t o r o f a b o u t for  s  absorber  b a s e d on t h e PPT a p p r o a c h n e e d s  i s thus not s u r p r i s i n g  F ,  t h e chance of f a i l u r e .  m o d e l s a n d a b o u t 2.0 f o r t h e t h e o r e t i c a l d e s i g n  It  100%.  predicted  ensure that  performs as expected or t o  2.32  without  uncertainty safety  absorption  towers  and  t o B o l l e s and F a i r [146].  t h e s e two  are  just diffusional  chemical reaction.  i n the f l u i d ,  required  distillation  1.7 i s u s u a l l y  the  with chemical  physical I t should mass  When r e a c t i o n s  considerably.  is  higher  reaction.  As a  f o r the  result, case  gas be  transfer  s i t u a t i o n becomes more c o m p l e x  increases factor  needed  of  take and the gas  257  T a b l e 7.5:  E f f e c t of u n c e r t a i n t y a s s o c i a t e d w i t h R on t h e p r e d i c t e d h e i g h t u s i n g o p e r a t i n g c o n d i t i o n s of Run T9 ( N a O H - C O o ) . O p e r a t i n g c o n d i t i o n : gas f l o w r a t e = 14.8 m o l / m s; l i q u i d f l o w r a t e = 9.5 m /m hr; i n l e t C0 c o n c e n t r a t i o n = 18.4%; i n l e t [OH ] =2.0 kmol/m . v  2  3  2 3  Uncertainty  P r e d i c t e d Height  F  s  +  0%  4.65  m  1 .0  +  20%  3.87  m  1.2  +  40%  3.32  m  1 .4  Rv  +  80%  2.58  m  1 .8  Rv  +  100%  2.32  m  2.0  R  v  R  v  R  v  F i s d e f i n e d as the r a t i o of the h e i g h t p r e d i c t e d w i t h u n c e r t a i n t y t o t h a t at the normal c o n d i t i o n . For example, i f a given uncertainty associated with R i s 100% f o r t h e c a s e , F w o u l d be e q u a l t o 2.0 (4.65/2.32). s  v  s  258  7.4  LIMITATIONS OF  PPT  There a r e p r a c t i c a l and fundamental PPT. B o t h  types of  limitations relate  measuring  the s p e c i f i c  Practical  Limitations:  *  The  PPM  column  absorption rate,  must  be  l i m i t a t i o n s of to the  *  The d i a m e t e r to  10  ensure  *  (particularly  times  v  constructed  temperature  of  that the w a l l e f f e c t  O n - l i n e and/or o f f - l i n e  of  materials  and i t s o p e r a t i n g and p r e s s u r e ) .  o f t h e PPM c o l u m n c a n n o t the diameter  of  R .  c o m p a t i b l e w i t h t h e a b s o r p t i o n system conditions  ability  the  be s m a l l e r t h a n 6  t h e random  packing  to  be a v a i l a b l e  to  i s negligible.  s e n s o r s must  measure t h e c o n c e n t r a t i o n s i n t h e l i q u i d and gas p h a s e s reliably.  *  An  adequate  supply  of  chemical  absorbent  m i x t u r e must be a v a i l a b l e ; when e x p e n s i v e i n v o l v e d , a r e g e n e r a t o r may be r e q u i r e d .  and  gas  chemicals are  259  Fundamental  *  Limitations:  For the  PPM  s e c t i o n of liquid  column the  and  *  full-scale  gas  c o n d i t i o n may  to represent  phases  n o t be met  the  conditions  column, the  must  be  well  bulk mixed.  for highly viscous  F o r m u l t i c o m p o n e n t s y s t e m s t h e number o f measurements interaction  may  become  between  prohibitatively  the absorption  of  in the  (This  liquids).  concentration l a r g e and  r a t e s may  the  not  be  e a s i l y determined.  *  For  multicomponent  conditions  for  u s u a l l y given the  systems,  inlet  full-scale industrial  and i t i s t h e r e f o r e  terminal, conditions  Iterative  the  p r o c e d u r e s may  for be  required  outlet  columns are  difficult  t h e PPM  and  to  not  specify  column as  well.  t o overcome  this  problem.  *  I f the a x i a l significant, a way  that  dispersion  i n the  f u l l - l e n g t h column  t h e PPM c o l u m n h a s t o be d e s i g n e d i n  similar  dispersion  occurs.  is such  260  7.5  PRACTICAL IMPLICATIONS OF THE  The t h e PPT  following section discusses c o n c e p t may  i n the order  i n h e i g h t . The  packing  (1.5"  f o r random  size  of  a  n a t u r a l gas (Petroleum height. we  size  the  situations.  i n d i a m e t e r and s e v e r a l i s u s u a l l y about  packing. gas  37.5  Rayong N a t u r a l  i s 3.75  m O.D.  using  the absorption  -  2.0  m h i g h c o u l d be  is still  p r o p e r t i e s of  the i n d u s t r i a l  t h e n be m e a s u r e d and used t o t h e one  c o n s t r u c t the R  i n Figure  7.3  v  f o r the  c o n d i t i o n s . This diagram could the a b s o r p t i o n  u s e d . The  column column  c o l u m n . The the f l u i d  R  v  this  of of  If  0.5 this  environment hydrodynamic  values  would  concentrations  - concentration diagram d e s i r e d ranges of  like  operating  t h e n be e m p l o y e d  to  predict  c a p a c i t y of the i n d u s t r i a l column  by  applying  the proposed P i l o t P l a n t Technique. A l t e r n a t i v e l y , column  Plant  rate occurring i n  able to d u p l i c a t e the  as f u n c t i o n s of  from  x 14.0 m i n  i s s m a l l enough t o be h a n d l e d i n l a b o r a t o r y  and t h e column  CO2  P a l l rings.  t h e P i l o t P l a n t T e c h n i q u e , a PPM  mm  example,  Separation  a b s o r b e r i s p a c k e d w i t h 50.0 mm simulate  t o 62.5  removing  Gas  is  meters  For a s p e c i f i c  absorber  A u t h o r i t y of T h a i l a n d )  The  m ID x 1.0  chemical  at  want t o  column  size  which  a b s o r b e r s used i n i n d u s t r y  o f a few m e t e r s  t o 2.5")  v a r i o u s ways i n  be a p p l i e d i n i n d u s t r i a l  In g e n e r a l , t h e s i z e of  the  PPT  c a n be u s e d t o  simulate  t h e model  this industrial size  column  261  s e c t i o n by be  s e c t i o n u s i n g t h e PPT  seen from  w o u l d be  If  t h i s example, the s c a l i n g  i n t h e o r d e r of one  structured  a b s o r b e r s , t h e PPM 0.03  t o 0.10  short-cut procedure. for this  can case  hundred.  packings  are  column diameter  m r a n g e and  factor  As  used  in  c o u l d be  industrial  reduced  t h e r e f o r e the s c a l i n g  to  factor  the would  increase considerably.  The  a b o v e s u g g e s t i o n c a n a l s o be u s e d f o r d e s i g n i n g  a b s o r b e r s . The absorber  design  diameter  p o i n t , the  velocities.  The  up t o  the  items  are  s i z e ; column dimensions  s i z e d b a s e d on proper  selected  diameter;  o f t h e PPM  design  criterion  determined:  fluid  superficial  knowledge  chemical parameters.  of  The  the  given i n Table  should  PPT  to r e t r o f i t be  i n order to  5.1. for  v  predict  very  P l a n t Technique does  hydrodynamic  method would  h e l p i n g d e s i g n e n g i n e e r s t o d e s i g n new process engineers  be  height.  As d i s c u s s e d p r e v i o u s l y , t h e P i l o t require  this  or  column i s then used t o o b t a i n t h e v a l u e s of R  the f u l l - s c a l e absorber  technique  At  of  column can then  the d e s i r e d range of f l u i d c o m p o s i t i o n s ,  not  determination  a r e a l r e a d y g i v e n i n S e c t i o n 2.3.  following  p a c k i n g t y p e and  T h i s PPM  steps  new  be  physico-  suitable  for  chemical absorbers  the e x i s t i n g  u s e f u l when  and  i t  columns. is  applied  or  This to  262  systems  t h a t use h i g h - e f f i c i e n c y p a c k i n g s and s o l v e n t s which  are favoured  by  industry.  a l r e a d y shown i n F i g u r e s capacity  Some  listed  s i m u l a t e these systems  based  to  these  2.11 a n d 2.12.  solvents are  either  of  packings  were  Some o f t h e  high-  i n T a b l e 7.6. on f i r s t  To d e s i g n  p r i n c i p l e s would  t o o c o m p l i c a t e d - i f indeed p o s s i b l e - o r would  large  errors  due  to  the  uncertainty  in  and be lead  parameter  estimations.  T a b l e 7.6: Some o f h i g h - c a p a c i t y s o l v e n t s .  Solvent  References  Sterically  h i n d e r e d amines  [ 7 1 , 101]  High concentration alkanolamines  [ 1 0 , 11]  Alkanolamines  [ 1 1 6 , 117]  i n nonaqueous s o l v e n t s  Alkanolamines i n a mixture of nonaqueous and aqueous s o l v e n t s  [ 1 0 , 11]  M i x t u r e o f amines  [ 1 0 , 11]  In  some  industrial  i m p u r i t i e s are unavoidable  situations, a n d c a n be  the a major  presence problem.  of To  263  quote from frustrating is  the  Bisio  [ 8 0 ] , " ....  problems  presence  smaller  of  scale  that  can  commercial  that  or  installation  consideration  to  modification  can  "  expense  be  removal made  were  pilot has  the  considered  built  great  good example i s t h e a c c u m u l a t i o n  and  or  operation studied  in  the  once  a  without  giving  adequate  from  process  streams,  difficulty  treating with  serious  Moreover,  impurities  with  most  a commercial  studies  been of  the  in  not  plant  only  I n gas  of  be encountered  impurities  laboratory  One  and  chemical  at  significant  solvents,  of the degradation  a  products  i n t h e s o l u t i o n when i t h a s been u s e d f o r a n e x t e n d e d p e r i o d of t i m e . R e c e n t l y , Kennard and Meisen  [118]  the  solution.  procedures existing  To  new  i f i ti s indeed  more  realistic  mentioned problems. situations,  the  way  column  of  absorber  factors  absorbers  or  into  simulating  deal  the  with  the  PPT method  very  be  operated  or similar  would above-  to  these  with  compositions  The e f f e c t i v e v a l u e s o f  be u s e d t o p r e d i c t t h e  using  the  p r i n c i p l e s w o u l d be  must  i n the i n d u s t r i a l plants.  or h e i g h t  these  to  t h e same  o b t a i n e d t h i s way c a n t h e n  compounds  f e a s i b l e . The PPT m e t h o d  By a p p l y i n g  PPM  solutions containing those  integrate  u n i t s b a s e d o n l y on f i r s t  provide a  and  both a b s o r p t i o n r a t e and c a p a c i t y  f o r designing  complicated,  [ 1 1 7 ] a n d Chakma  have r e p o r t e d t h a t t h e s e d e g r a d a t i o n  could s i g n i f i c a n t l y affect of  Meisen  such  solutions. This  a p p l i c a t i o n o f t h e PPT method t h a t a w a i t s  the as R  v  capacity i s an  further research.  264  CHAPTER 8 SUMMARY OF RESULTS AND  The  r e s u l t s and  CONCLUSIONS  p r i n c i p a l conclusions  drawn from  the  r e s e a r c h s t u d i e s may be summarized as f o l l o w s :  SOLUBILITY  *  OF CO  IN AMP SOLUTIONS  2  S i g n i f i c a n t l y extended r e s u l t s from the p r e v i o u s are r e p o r t e d . These s o l u b i l i t y  data cover  the  works typical  o p e r a t i n g ranges of absorbers.  *  The  modified  experimental for use i n  Kent-Eisenberg  model  data q u i t e a c c u r a t e l y the design of  represents  and i s w e l l  r e g e n e r a t i v e AMP  the suited  separation  processes.  *  The s o l u b i l i t y of comparison with higher a t low  C0  2  in  that of  AMP s o l u t i o n C0  2  i n MEA s o l u t i o n ,  temperatures ( <  high temperatures ( >60 °C ).  was found,  60 °C )  to  and lower  by be at  265  EXPERIMENTAL  *  AND SIMULATION  RESULTS  OF FULL  SCALE  ABSORBERS  Comprehensive p i l o t p l a n t d a t a i n c l u d i n g gas and l i q u i d c o n c e n t r a t i o n s and temperature p l a n t absorber  p r o f i l e s a l o n g the p i l o t  f o r t h e CO2 a b s o r p t i o n i n t o NaOH and MEA  - s o l u t i o n s were r e p o r t e d .  *  Good  agreement  was  found  between  the  experimental  measurements and model p r e d i c t i o n s f o r t h e C02 NaOH and -  CO2-MEA systems  except  at  loadings  approaching  0.5  moles of CO2 per mole of MEA.  *  T h e o r e t i c a l model  verification  c o n c e n t r a t i o n and temperature  should  be  based  on  p r o f i l e s and not j u s t  on  the c o n d i t i o n s a t the a b s o r b e r t o p and bottom.  *  The enhancement f a c t o r  v a r i e s s i g n i f i c a n t l y along  the  a b s o r p t i o n column  must be  for  and  accurately  known  r e l i a b l e modelling.  THE PILOT  *  PLANT TECHNIQUE  (PPT)  A new method,  called  the " P i l o t  been proposed  for sizing  c h e m i c a l r e a c t i o n . T h i s new  P l a n t Technique"  gas-absorption  towers  d e s i g n t e c h n i q u e does  has with not  266  require  explicit  physico-chemical  The  results  of  of  hydrodynamics  and  parameters.  obtained  s y s t e m s show sizing  knowledge  that  C0 -NaOH  w i t h the  t h e PPT  absorbers;  the  2  can  be u s e d  accuracy  and  C0 AMP  for  precise  _  2  falls  typically  w i t h i n ± 1 2 %.  Since the accuracy depends o n l y r a t e s and  on t h e  values obtained  measurements  contacting  operations  involving  R  v  must be  drawback of the  t o be  The  may  PPT  systems.  PPT  be  that  continuous  transfer  with  columns).  i s t h a t the v a l u e s , of t h e PPM  s p e c i a l l y c o n s t r u c t e d and  not  flow  reactors, extraction  obtained experimentally i n  w h i c h has  PPT  l a b o r a t o r y models.  mass  r e a c t i o n ( e . g . p a c k e d bed  primary  fluid  be a p p l i e d t o o t h e r  columns, r e a c t i v e d i s t i l l a t i o n  The  of the  low c o m p a r e d w i t h  f r o m f i r s t p r i n c i p l e s and  may  from the  the u n c e r t a i n t y a s s o c i a t e d w i t h  is relatively  P o t e n t i a l l y , t h e PPT  chemical  v  compositions,  i t s determination obtained  of R  practicalfor  column  operated.  multicomponent  267  CHAPTER 9 RECOMMENDATIONS FOR FURTHER WORK  SOLUBILITY  STUDIES  C o n s i d e r a b l e work h a s been in  aqueous  solutions  s u b s t a n t i a l work mixtures  of  of  h a s been  amines. I t  conduct such experiments the  literature  that  done on t h e CO2  single  amines.  However,  no  reported  on CO2  solubility  in  t h e r e f o r e be  worthwhile  to  would  s i n c e t h e r e a r e some s u g g e s t i o n s i n  these  solutions  may  a b s o r p t i o n c a p a c i t y a s w e l l a s mass t r a n s f e r  COMPUTER MODELLING  a p p r o a c h e s 0.5 experimental  moles  n o t a c c u r a t e when o f CO2  per  the l i q u i d  mole o f  amine.  a n d m o d e l l i n g work s h o u l d be c o n d u c t e d  partially  loaded  investigated, especially at 1.0 m o l e s o f C 0  2  higher  rate.  6, t h e p r e d i c t i o n o f  t h e s e a s p e c t s . The p h y s i c o - c h e m i c a l k i n e t i c s of  have  ......  As d i s c u s s e d i n C h a p t e r performance i s s t i l l  solubility  p r o p e r t i e s and  s o l u t i o n s should high l o a d i n g s (i.e.-  / mole o f a m i n e ) .  be  absorber loading Further t o study reaction further  a t 0.4  to  268  THE  PILOT  PLANT  In t h i s  thesis,  successfully variety  TECHNIQUE  tested  the  PPT  with  two  of c o n d i t i o n s . I t  conduct f u r t h e r  t e s t s on  design  approach  different  has  under  a  w o u l d t h e r e f o r e be w o r t h w h i l e  to  -the PPT  a n d u n d e r p l a n t c o n d i t i o n s . The  with  ideal  a c o m p l e t e d a t a s e t o f an e x i s t i n g  systems  been  industrial situation  industrial  absorbers  i s to obtain  absorber which  i n c l u d e t h e t e m p e r a t u r e and c o m p o s i t i o n p r o f i l e s as w e l l  as  the d e t a i l s of  to  predict  t h e a b s o r b e r . The  PPT c a n t h e n  the tower h e i g h t o r i t s a b s o r p t i o n  be u s e d  capacity.  I t w o u l d a l s o be w o r t h w h i l e t o c o n d u c t f u r t h e r t e s t s t h e PPT  i n other i n d u s t r i a l  a b s o r p t i o n o f more t h a n one  situations  such as  on  simultaneous  gas s p e c i e s and t r a y  absorption  towers.  As d i s c u s s e d from f i r s t NaOH. can  earlier,  principles  be  obtained v  c a n be  systems CO2-AMP,  experimentally. obtained  C02~  such as the R  values  v  Fundamentally,  i n t h e model column  h y d r o d y n a m i c s and p h y s i c o - c h e m i c a l p a r a m e t e r s , p r o v i d e d  the  exploratory  of the works  system i s  have  i n order  to  could the  model  back-calculations  computed  estimate  kinetic  for  values  v  systems l i k e  e x p e r i m e n t a l v a l u e s of R be u s e d  R  f o r well-known  H o w e v e r , f o r new only  the  known. R e s u l t s  suggested  that  such  from  some  parameter  269  estimation •optimization set  may  be  feasible  t e c h n i q u e s c o u l d be  o f unknown p a r a m e t e r s  between  [150]. employed  Theoretically, t o determine  the  w h i c h w o u l d g i v e t h e minimum  error  t h e computed a n d e x p e r i m e n t a l a b s o r p t i o n r a t e s .  many c a s e s  when  the  rate constant  coefficients  a r e n o t known, t h i s  extract  unknown  the  parameters.  The  suggested  h e r e may be u s e d  chemical  reaction  systems  absorbents.  mass  transfer  t e c h n i q u e c a n be a p p l i e ' d t o  approach  high-efficiency  and/or  In  parameter  estimation  f o r gas a b s o r p t i o n  involving  new  packings  with and/or  270  NOMENCLATURE  a  packing  Cf  o f component j i n t h e l i q u i d ,  concentration  J  C  P , j heat c a p a c i t y  D  F  P,L  heat c a p a c i t y  J  diffusivity  S  safety  of solution,  3  o f component j , m /s 2  ( s e e T a b l e 7.5)  factor  Gl  molar gas flow  H  Henry's law c o n s t a n t , kmol/m .kPa  mass v e l o c i t y , kg/m .s 2  r a t e o f component I , k m o l / m . s 2  3  h e a t t r a n s f e r c o e f f i c i e n t , kJ/s.m .°K 2  G  HR  heat of a b s o r p t i o n  enhancement  *C  ionic  K  equilibrium  K  and r e a c t i o n ,  heat of v a p o r i z a t i o n  S  I  of solvent  S, k J / k m o l  factor  strength,  kmol/m  3  constant  o v e r a l l g a s mass t r a n s f e r c o e f f i c i e n t , k m o l / m . s . kPa) 2  G  reaction  G  p h y s i c a l g a s mass t r a n s f e r c o e f f i c i e n t , k m o l / m . s .kPa)  o k  rate constant,  m /kmol.s 3  2  L  physical  l i q u i d mass t r a n s f e r c o e f f i c i e n t , m/s  L  liquid  L'  l i q u i d mass v e l o c i t y , kg/m .s  M  f i l m conversion  N  kJ/kmol  2  k  k  3  kJ/m .°K  gas  H  kmol/m  o f component j i n t h e g a s , k J / k m o l . °K  G'  h  2  factor  C  C  m /m 3  i n t e r f a c i a l a r e a p e r u n i t volume o f p a c k i n g ,  v  j  flow  r a t e , m /m .s 3  2  2  mass t r a n s f e r  parameter  f l u x o f component j , kmol/m  2  s  271  P R  a  total  pressure,  specific  r a t e of a b s o r p t i o n  of p a c k i n g , Rv  specific kmol/m  2  kPa  kmol/m  2  per u n i t i n t e r f a c i a l  s  r a t e of a b s o r p t i o n  p e r u n i t volume of  r  r a t e of r e a c t i o n i n the l i q u i d  T  temperature,  t  time,  yj  z  °K  o f component  j , kmol j/kmol I  m o l e f r a c t i o n o f component height, m  Superscripts *  phase, kmol/m  s  packing  equilibrium  Subscripts A  absorbed  B  reagent i n l i q u i d  G  gas  I  inert carrier  i  interface  j  g e n e r a l i z e d component  L  liquid  m  model  S  inert  t  total  packing,  s  mole r a t i o  compound  liquid  area  gas  solvent  j  j , kmol j / m o l  3  s  272  w  Greek  water  Letters  v  stoichiometric  p  density,  7  l i q u i d CO2  kg/m  coefficient 3  hold-up,  loading,  8  l i q u i d  film  u  viscosity,  m  3  of  liquid/m  moles  of  CC^/mole  thickness, mPa  s  mm  (centipoise)  3  of of  packing amine  273  REFERENCES  1.  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" N a t u r a l Gas P r o c e s s i n g P r i n c i p l e s a n d Technology - Part I " , U n i v e r s i t y of Calgary, A l b e r t a , 1987. 150. P i n t o l a , T., P r i v a t e C o m m u n i c a t i o n a t t h e C h e m i c a l E n g i n e e r i n g D e p a r t m e n t , The U n i v e r s i t y o f B r i t i s h C o l u m b i a , 1990.  286  APPENDIX A ANALYSIS  A.l  [73].  following  The f i r s t  (carbonate  procedure  titration  + hydroxide)  u s i n g methyl orange solution,  the  barium c h l o r i d e  2  solution  is  hydroxide  first  carbonate  Sample  If  the  first  is  to determine  is  from the  total  with standard  In a s e c o n d  precipitated  Reference alkali  1 N HCl,  sample of  with a s l i g h t  the  excess  solution:  then  = BaC0  2  titrated  3  the  and  (insoluble)  with standard  indicator.  content,  titration,  is  SOLUTION  obtained  indicator.  + BaCl  3  p h e n o l p h t h a l e i n as the  as  is  by t i t r a t i o n  carbonate  Na C0  The  SAMPLES  C O M P O S I T I O N D E T E R M I N A T I O N OF C A U S T I C  The  of  OF L I Q U I D  The by  volume  latter  acid  2NaCl  1 N HCl titration  subtracting of  +  this  using gives  from"  the  for  the  required for  the  required  obtained.  Calculation  sample and  respectively.  size second  = 5.0  ml and  titrations  the are  acid 10.0  and  5.0  ml,  287  Therefore, [Na ]  = total alkali  [OH ]  = h y d r o x i d e c o n t e n t = ( 5 . / 5 . ) x 1 . 0 = 1.0  +  -  [C0  The  = 3  major  = ( 1 0 . 0 / 5 . 0 ) x 1 . 0 = 2.0  contribution HCl  to  which  +  sample the  and  [OH~]  (5.0x10~  error  3  the  associated  i s within  moles). For  i n obtaining  error  i s accurate  Therefore, the u n c e r t a i n t y [Na ]  N  ] = c a r b o n a t e c o n t e n t = ( 1 0 . - 5 . ) / ( 5 . x 2 . ) = 0.5  measurement of  of  N  [OH ] -  is within  ±  volume 0.1  ml.  with the determination  ± 1.0X10~ t h e above  i s 2.0  the  N  %.  4  moles per  sample  5  ml  calculation,  288  A.2  DETERMINATION OF  The  Gas  following  measuring  f l a s k , A,  CARBON DIOXIDE LIQUID LOADING  d e t a i l s a r e t a k e n from R e f e r e n c e  apparatus.  F i g u r e A.1.  by g l a s s T - t u b e ,  Connect  tube,  D,  leveling  flask  A, u s e  E.  For  decomposition  B, p r o v i d e d w i t h s t o p c o c k , C,  graduated gas-measuring bulb,  connected  in  250 ml  f i t t e d w i t h 2 - h o l e r u b b e r s t o p p e r , t h r o u g h one passes extended  e x t r a - l o n g t i p bent  Pyrex  flask  h o l e of  which  to  decomposition flask  permit  tube graduated  below top marking  i n t e r v a l s , and  rotation in  to allow  Displacement distilled  water.  leveling  acid  fitted  with  Add  1 g  Connect  t o T-tube  flask.  with  Use  gas-  a t p o i n t 25  ml  f o r g r a d u a t i n g upward f r o m 0  to  D i s s o l v e 100  Connect  gas-measuring tube.  g NaCI i n  350 ml  o f NaHC03 and 2 ml M e t h y l  (decided pink).  This solution bulb  buret  b u l b , E, w i t h l o n g r u b b e r  solution.  t o make j u s t removed.  leveling  of  ml w i t h 0 mark  25 ml and downward f r o m 0 t o 200 m l . t u b e t o 300 ml  Use  t o pass through rubber stopper.  g l a s s t u b e l e a d i n g from  measuring  with  t i p o f 25 ml b u r e t , F, and t h r o u g h o t h e r , t h e  i n m l , numbered a t 1 ml  rubber t u b i n g  to  turn  g l a s s t u b e o f same d i a m e t e r as c o n n e c t i n g T - t u b e . graduted  [114].  i s used  in  Stir  until  orange  a l lC0  gas m e a s u r i n g  of  tube  2  is and  Figure  A . 1 : Gas m e a s u r i n g  apparatus  [114].  290  Determination.  and  connect  ml o f  flask with  s t o p c o c k C, and solution  5  Pipette  liquid  using leveling bulb  equal  decomposition.) temperature  to Let  Figure A.1.  a p p a r a t u s , see  t o 1.0 ml g r a d u a t i o n a b o v e  practically  sample i n t o f l a s k  volume  E, b r i n g 0 mark.  of  acid 1  apparatus stand  and p r e s s u r e  A, Open  displacement 10 ml  is  used  in  minute  for  (This to  be  to 2  within apparatus to  come t o  room  conditions.  Close stopcock,  lower  leveling  p r e s s u r e w i t h i n a p p a r a t u s , and t o decompose t h e p r e v e n t escape  bulb  somewhat  of l i b e r a t e d C 0  2  f l a s k A from  tube.  lower i n l e v e l i n g Rotate  and  then  bulb than that vigorously  L e t s t a n d 5 min  Equalize pressure in  measuring  agitate  air  s u r r o u n d i n g and a l s o b a r o m e t r i c p r e s s u r e .  standard  to  mix  equilibrium. bulb,  Observe temperature  be d e t e r m i n e d  by t i t r a t i o n  of  with  1N H C l t o m e t h y l o r a n g e e n d - p o i n t .  Calculation  factor,  flask  using leveling  r e a d v o l u m e o f gas  amine c a n  solution  gas-measuring  to secure  tube,  i n the tube.  in  and  total  To  through a c i d buret into a i r ,  contents intimately.  The  HCl  b u r e t F.  a t a l l times d u r i n g d e c o m p o s i t i o n keep d i s p l a c e m e n t at l e v e l  reduce  10 ml o f 2 M  s l o w l y add  sample i n the  to  of  f , Q  CO  2  which  loading.  is  given  M u l t i p l y ml i n Table  o f e v o l v e d gas A.1,  for  the  by  given  291  t e m p e r a t u r e and  pressure.  %CC>2 c o n t e n t by  wt. o f s a m p l e  c o n v e r t e d t o moles of C 0 ((ml Sample  2  of e v o l v e d  The c o r r e c t e d  reading/10  s i z e o f 1.7  gives  g. T h i s c a n  be  by gas)*f /l0)/l00)*(1.7/40) g  calculation. s a m p l e s i z e = 5.0  ml  m l o f 1 N HCI = 10 m l e v o l v e d g a s = 55 m l Temp. = 16 °C, P r e s s u r e = 758.5 mmHg, f  g  =  1.07  Therefore, total  a m i n e = ( 1 0 / 5 ) * 1 . 0 = 2.0  moles of C 0  2  = 55*1.07*1.7/(10*100*40) = 2.5X10~  C0  2  loading  ml  3  moles of  C0  2  = 2.5x10" /(2*5/l000) 3  = 0.25 m o l e s o f C 0 / m o l e  o f amine  2  The m a j o r e r r o r s a s s o c i a t e d  i n t h i s a n a l y s i s are as  * m e a s u r e m e n t o f e v o l v e d g a s ± 1.0 ( a f f e c t t h e C02 c o n t e n t by 1.8 %)  follows:  ml  * m e a s u r e m e n t o f room t e m p e r a t u r e ± 1.0 ( a f f e c t f by 0.5 %)  °C  g  * m e a s u r e m e n t o f HCI ± 0.1 m l ( a f f e c t t h e t o t a l amine ± 1.0 %) Therefore, the error which  is  i n C0  approximately  determination.  2  /  loading 40  %  i s i n t h e o r d e r o f 3.3 more  than  the  %  [OH-]  292 Table  A . 1 : The v a l u e s o f f pressure [114].  q  for a variety  of temperature  ( B a s e d o n s a m p l e w e i g h i n g 1.7000 g) ( M u l t i p l y n u m b e r of m l g a s e v o l v e d f r o m 1.7000 g s a m p l e b y f a c t o r t h a t c o r r e s p o n d s w i t h e x i s t i n g a t m o s p h e r i c c o n d i t i o n s a n d d i v i d e b y 10 t o o b t a i n % C O j b y wt i n s a m p l e . )  S3.VT  15.0°C  15.5°C S9.9T  16.0°C 60.8-F  16.S-C 6I.7°F  17.0-C 62.6°F  17.5-C K3.5»F  18.0°C 64.-*°F  18.5°C 65.3°F  I9.0°C 66.2°F  19.5-C 67.1»F  Inches  700 702 704 70S 708 710  0.99194 0.99494 0.99794 1.00Q94 1.00394 1.00694  0.99006 0.99300 0.99544 0.99886 1.00183 1.00477  0.98818 0.99106 0.99394 0.99682 0.99971 1.00259  0.98573 0.98862 0.99147 0.99435 0.99723 1.00012  0.98329 0.98618 0.98900 0.99188 0.99476 0.99765  0.98082 0.98368 0.98653 0.98941 0.99226 0.99512  0.9783S 0.98118 0.98406 0.98694 0.98976 0.99259  0.9758S 0.97868 0.98156 0.98406 0.98726 0.99009  0.97335 0.97618 0.97906 0.98188 0.98476 0.98759  0.97085 0.97368 0.97653 0.97938 0.98224 0.98506  27.56 27.64 27.72 27.80 27.87 27.95  712 71< 716 718 720  1.00994 1.01294 1.01594 1.01894 1.02194  1.00767 1.01061 1.01356 1.01650 1.01949  1.00541 1.00829 1.01118 1.01406 1.01694  1.00294 1.00582 1.00871 1.01156 1.01444  1.00047 1.00335 1.00624 1.00906 1.01194  0.99795 1.00080 1.00368 1.00653 1.00941  0.99541 1.99824 1.00112 1.00400 1.00688  0.99291 0.99576 0.99861 1.00150 -1.00435  0.99041 0.99329 0.99612 0.99900 1.00182  0.98788 0.99073 0.99358 0.99644 0.9992S  28.03 28.11 28.19 28.27 28.35  722 724 726 728 730  1.02482 1.02771 1.03059 1.03347 1.03635  1.02232 1.02521 1.02809 1.03097 1.03385  1.01982 1.02271 1.02S59 1.02847 1.03135  1.01732 1.02021 1.02306 1.02594 1.02882  1.01482 1.01771 1.02053 1.02341 1.02629  1.01229 1.01518 1.01800 1.02088 1.02374  1.00976 1.01265 1.01574 1.01835 1.02118  1.00720 1.01009 1.01291 1.01580 1.01862  1.00465 1.00753 1.01035 1.01324 1.01606  1.00209 1.00497 1.00779 1.01065 1.01347  28.43 28.50 28.58 28.66 28.74  732 734 736 738 740  1.03924 1.04218 1.04506 1.04794 1.05082  1.03674 1.03915 1.042S3 1.04541 1.04829  1.03424 1.03712 1.04000 1.04288 1.04576  1.03171 1.03459 1.03744 1.04037 1.04321  1.02918 1.03206 1.03488 1.03776 1.04065  1.02662 1.02950 1.03232 1.03521 1.03806  1.02406 1.02694 1.02976 1.03265 1.03547  1.02147 1.02435 1.02718 1.03006 1.03288  1.01888 1.02176 1.02459 1.02747 1.03029  1.01629 1.01919 1.02200 1.02486 1.02768  28.82 28.90 28.98 29.06 29.13  742 744 746 748 750  1.05371 1.05659 1.05947 1.06235 1.06524  1.05118 1.05403 1.05691 1.05929 1.06218  1.0486S 1.05147 1.05435 1.05724 1.06012  1.04609 1.04991 1.05180 1.05418 1.05748  1.04353 1.04635 1.04924 1.05212 1.05494  1.04094 1.04377 1.04665 1.049S3 1.05235  1.03835 1.04118 1.04406 1.04694 1.04976  1.03577 1.03859 1.04147 1.04433 1.04715  1.03318 1.03600 1.03888 1.04171 1.04453  1.03056 1.03338 1.03624 1.03906 1.04189  29.21 29.29 29.37 29.45 29.53  752 754 756 758 760  1.06818 1.07106 1.07394 1.07682 1.07971  1.06512 1.06847 1.07135 1.07423 1.07712  1.06306 1.06588 1.06876 1.07165 1.07453  1.06047 1.06330 1.06618 1.06906 1.07191  1.05788 1.06071 1.06359 1.06647 1.06929  1.05527 1.05812 1.06197 1.06386 1.06668  1.05265 1.05553 1.05835 1.06124 1.06406  1.05003 1.05289 1.05571 1.05859 1.06141  1.04741 1.05024 1.05306 1.05594 1.05876  1.04477 1.04759 1.05041 1.05330 1.05612  29.61 29.69 29.76 29.84 29.92  762 764 766 768 770  1.08259 1.08547 1.08841 1.09129 1.09418  1.08050 1.08288 1.08580 1.08868 1.09156  1.07741 1.08029 1.08318 1.08606 1.0  1.07480 1.07768 1.08056 1.08344 1.08630  1.07218 1.07506 1.07794 1.08082 1.08365  1.06956 1.07244 I.O7S30 1.07818 1.08100  1.06694 1.06982 1.07265 1.07553 1.07835  1.06430 1.06715 1.06997 1.07285 1.07567  1.06165 1.06447 1.06729 1.07018 1.07300  1.05897 1.06179 1.06462 1.06750 1.07032  30.00 30.08 30.16 30.24 30.31  20.0'C 68.0*F  6S.9°F  21.5 C 70.7T  22.0°C 71.e"F  22.5 C 72.5-F  23.0°C 73.4"F  23.5°C 74J°F  24.0«C 7S.rF  24.5°C 76.1»F  Inches  700 702 704 706 708 710  0.96835 0.97118 0.97400 0.97688 0.97971 0.98253  0.96564 0.96850 0.97132 0.97420 0.97703 0.97988  0.96294 0.96582 0.96865 0.97153 0.97435 0.97724  712 714 716 718 720  0.98535 0.98818 0.99106 0.99388 0.99671  0.98273 0.98556 0.98844 0.99126 0.99412 0.99694 0.99982 1.00265 1.00547 1.00829  0.95265 0.95547 0.95835 0.96118 0.96400 0.96682 0.96971 0.97253 0.97535 0.97818 0.98106  0.94508 0.94788 0. 95067 0.,95344 0..95626 0..95905  0. 99953 1.00241 1.00524 1.00806 1.01088  732 734 736 738 740  1.01371 1.01659 1.-01941 1.02224 1.02506  1.01112 1.01497 1.01679 1.01962 1.02244  1.00853 1.01135 1.01418 1.01700 1.01982  742 744 746 748 750  1.02794 1.03076 1.03359 1.03641 1.03924  I.02S29 1.02811 1.03094 1.03376 1.03659  0.98388 0.98665 0.98947 0.99229 0.99512 0.99788 1.00071 1.00353 1.00629 1.00912  0.96712 0.96991 0.97273 0.97556 0.97838 0.98120 0.98397 0.98679 0.98961 0.99241 0.99517 0.99799 1.00083 1.00359 1.00643  0.96453 0.96729 0.97012 0.97294 0.97571  0.9943S 0.99724 1.00006 1.00288 1.00571  1.0226S 1.02547 1.02829 1.03112 1.03394  752 754 756 758 760  1.04212 1.04494 1.04776 1.05065 1.05347  1.03944 1.04226 1.04508 1.04797 1.O5079  1.03676 1.03959 1.04241 1.04529 1.04812  1.05629 1.05912 1.06194 1.06482 1.06765  1.05361 1.05644 1.05926 1.06212 1.06424  1.01194 1.01471 1.01753 1.02035 1.02318 1.02594 1.02876 1.03159 1.03441 1.03718  1.00923 1.01200 1.01482 1.01762 1.02045 1.02321 1.02603 1.02883 1.03165 1.03442  1.00653 1.00929 1.01212 1.01488 1.01771  762 764 766 768 770  0.95509 0.95794 0.96082 0.96371 0.96656 0.96938 0.97227 0.97512 0.97800 0.98083 0.98371 0.98653 0.98932 0.99215 0.99497 0.99781 1.00056 1.00338 1.00620 1.00900 1.01182 1.01464 1.01752 1.02024 1.02306 1.02589 1.02868 1.03150 1.03433 1.03715 1.03992  0.94776 0.95059 0.95335 0.9S612 0.95894 0.96176  722 724 726 728 730  1.05094 1.05376 1.05659 ' 1.05941 1.06224  0.95753 0.96041 0.96329 0.96624 0.96912 0.97195 0.97483 0.97771 0.98065 0.98348 0.98636 0.98918 0.99200 0.99483 0.99765 1.00041 1.00324 1.00606 1.00888 1.01171 1.01453 1.01735 1.02212 1.02294 1.02576 1.02859 1.03141 1.03424 1.03706 1.03988 1.04265 1.04S47 1.04829 1.05112 1.05394 • 1.05676  0.95020 0.95303 0.95585 0.95865 0.96147 0.96429  0.98012 0.98294 0.98582 0.98865 0.991S3  0.96023 0.96311 0.96S97 0.96888 0.97173 0.97459 0.97747 0.98032 0.98323 0.98606 0.98894 0.99176 0.99462 0.99746 1.00027 1.00306 1.00588 1.00870 1.01153 1.01435 1.01717 1.02000 1.02279 1.02561 1.02844 1.03126 1.03408 1.03691 1.03973 1.04259 1.04539 1.04821 1.05103 1.05386 1.05668 1.05950  1.04274 1.04556 1.04839 1.05118 1.05400  1.04000 1.04282 I.0456S 1.04841 1.05123  1.03724 1.04003 1.04285 1.04562 1.04844  1.03447 1.03723 1.04005 1.04282 1.04564  21.VC 69.PF  0  0  0.97853 0.98129 0.98412 0.98694 0.98971 0.99247 0.99529 0.99812 1.00088 1.00371  1.02047 1.02329 1.02606 1.02888 1.03165  27.56 27. 64 27. 72 27. 80 . 27. 87 27. 95 28. 03 0..96182 0..96461 28. 11 0..96741 28.,19 0.,97023 28. 27 0..97300 28. 35 28. 43 0..97582 0..97858 28. so 0..98141 28. 58 0..98420 28.,66 0..98697 28. 74 28..82 0..98973 0..99255 28. 90 0..99538 28. 98 0..99815 29..06 1..00095 29. 13 29. 21 1..00377 1..00643 29..29 .00936 29.,37 .01212 29..45 1 1..01492 29.,53 29..61 1..01771 1..02050 29..69 1 .02326 29..76 1..02608 29..84 1 .02886 29..92 30. 00 1 .03164 1 .03444 30..08 1 .03723 30. 16 1 .04003 30..24 .04282 30..31.  (Continued) ' C a l c d f r o m 1.976 - wt 1 L C O j at 0*C. 760 m m p r e s s u r e , a n d 41* l a t i t u d e . F o r m u l a g i v e n b y W P a r r J. Am. Chem. S o c . 31. 237(1909).  and  Table A . l 52.007  ( C o n ' t ) : The v a l u e s o f f for a temperature and p r e s s u r e [1T4 ] .  variet;  q  Correction factors for gasometric determination of carbon d i o x i d e — C o n c l u d e d . 0  (Based on sample weighing 1.7000 g) (Multiply number of ml gas evolved from 1.7000 g sample by factor that corresponds with existing atmospheric conditions a n d divide by 10 to obtain % COj by wt in sample.)  mm  25.0°C 77.0»F  25.5°C 77.9°F  26.0°C 78.8°F  265°C 79.7^  27.0°C W-fff  27.5°C 81.5°F  28.0°C 82.4°F  28.5°C 83.3°F  29.0°C 84.2">F  29.5°C 85.1°F  Inches  700 702 704 706 708 710 712 714 716 718 720 722 724 726 728 730 732 734 736 738 740 742 744 746 748 750 752 754 756 758 760 762 764 766 768 770  0.94241 0.94518 0.94800 0.95076 0.95359 0.9563S 0.95812 0.96194 0.96471 0.96753 0.97029 0.97312 0.97588 0.97871 0.98147 0.98424 0.98700 0.98982 0.99265 0.99541 0.99818 1.00100 1.00376 1.00659 1.00935 1.01212 1.01494 1.01771 1.02047 1.02329 1.02606 1.02882 1.03165 1.03441 1.03724 1.04000  0.93373 0.94250 0.94532 0.94808 0.95088 0.95364 0.95644 0.95923 0.96200 0.96482 0.96758 0.97038 0.97314 0.97594 0.97870 0.98147 0.98423 0.98705 0.98985 0.99261 0.99538 0.99820 1.00097 1.00376 1.006S3 1.00936 1.01211 1.01483 1.01764 1.02047 1.02323 1.02600 1.02880 1.03156 1.03435 1.03712 1  0.93706 0.93982 0.94256 0.94541 0.94818 0.95094 0.95376 0.95653 0.95929 0.96212 0.96488 0.96765 0.97041 0.97318 0.97594 0.97871 0.98147 0.98429 0.98706 0.98982 0.99259 0.99541 0.99818 1.00094 1.00371 1.00659 1.00929 1.01206 1.01482 1.01765 1.02041 1.02318 1.02594 1.02871 1.03147 1.03424  0.93432 0.93708 0.93988 0.94267 0.94544 0.94820 0.95100 0.95376 0.95655 0.9593S 0.96213 0.69488 0.96764 0.97041 0.97319 0.97594 0.97871 0.98165 0.98426 0.98703 0.98976 0.992SS 0.99535 0.99809 1.00088 1.00370 1.00644 1.00921 1.01197 1.01477 1.01753 1.02030 1.02306 1.02583 1.028S9 1.03136  0.93159 0.93435 0.93712 0.93994. 0.94271 0.94547 0.94824 0.95100 0.9S382 0.95659 0.95939 0.96212 0.96488 0.96765 0.97041 0.97318 0.97594 0.97871 0.98147 0.98424 0.98694 0.98976 0.99253 0.99529 0.99806 1.00082 1.00359 1.00635 1.00912 1.01188 1.01465 1.01741 1.02018 1.02294 1.02571 1.02847  0.92885 0.92161 0.93438 0.93717 0.93994 0.94267 0.94544 0.94820 0.95100 0.95376 0.95655 0.95929 0.96206 0.96482 0.96758 0.97036 0.97309 0.97585 0.97861 0.98138 0.98409 0.98691 0.98967 0.99241 0.99517 0.99796 1.00071 1.00342 1.00624 1.00900 1.01174 1.01450 1.01727 1.02003 1.02280 1.02556  0.92612 0.92888 0.93165 0.93441 0.93718 0.93988 0.94265 0.94541 0.94818 0.95094 0.95371 0.95647 0.95924 0.96200 0.96476 0.96753 0.97024 0.97300 0.97576 0.97835 0.98124 0.98406 0.98682 0.98953 0.99229 0.99506 0.99782 1.00059 1.00335 1.00612 1.00882 1.01159 1.01435 1.01712 1.01988 1.02265  0.92332 0.92608 0.92882 0.93158 0.93435 0.93706 0.93982 0.94258 0.9453S 0.94809 0.95085 0.95361 0.95638 0.95912 0.96188 0.96464 0.96735 0.97012 0.97288 0.97564 0.97835 0.93115 0.98391 0.98662 0.98938 0.99215 0.99491 0.99738 1.00041 1.00318 1.00588 1.00865 1.01141 1.01418 1.01611 1.01968  0.92053 0.92329 0.92600 0.92876 0.93153 0.93424 0.93700 0.93976 0.94253 0.94524 0.94800 0.95076 0.95353 0.95624 0.95900 0.96176 0.96447 0.96724 0.97000 0.97276 0.97547 0.97824 0.98100 0.98371 0.98647 0.98924 0.99200 0.99471 0.99747 1.00024 1.00294 1.00571 1.00847 1.01124 1.01394 1.01671  0.91773 0.92047 0.92320 0.92594 0.92870 0.93141 0.93414 0.93691 0.93964 0.94238 0.94512 0.94788 0.95062 0.95332 0.95609 0.95885 0.961S6 0.96429 0.96706 0.96982 0.97253 0.97529 0.97806 0.98076 0.98353 0.98626 0.98903 0.99173 0.99450 0.99724 0.99995 1.00274 1.00547 1.00824 1.01094 1.01371  27.56 27.64 27.72 27.80 27.87 27.95 28.03 28.11 28.19 28.27 28.35 28.43 28.50 28.58 28.66 28.74 28.82 28.90 28.98 29.06 29.13 29.21 29.29 29.37 29.45 29.53 29.61 29.69 29.76 29.84 29.92 30.00 30.08 30.16 30.24 30.31  ;  mm 700 702 704 706 708 710 712 714 716 718 720 722 724 726 728 730 732 734 736 738 740 742 744 746 748 750 752 754 756 758 760 762 764 766 768 770  30.0X 86.0°F . 0.91494 0.91765 0.92041 0.92312 0.92588 0.92859 0.93129 0.93406 0.93676 0.93953 0.94224 054500 0.94771 0.95041 0.95318 0.95594 04S865 0.96I3S 0.96412 0.96688 056959 0.9723S 057512 0.97782 0.98059 0.98329 0.98606 058876 0.99153 059429 059700 0.99976 1.00247 1.00524 1.00794 1.01071  305°C 86.9T 0.91203 0.91476 0.91750 052024 052297 052567 0.92841 0.93115 0.93388 0.93662 053932 054209 0.94479 0.94750 055026 055300 055578 0.95844 0.96118 0.96394 056665 0.96941 057215 057485 057762 0.98032 0.98306 0.98579 0.98853 0.99129 0.99400 059673 0.99948 1.00221 1.00491 1.00768  31.0°C 87.PF 0.90912 051188 0.91459 0.91735 0.92006 052276 0.92553 052824 0.93100 053371 0.93641 053918 0.94188 0.94459 054735 055006 055282 0.95553 055824 0.96100 0.96371 0.96647 056918 0.97188 0.97465 0.97735 0.98006 0.98282 0.98553 0.98829 059100 0.99371 059647 0.99918 1.00188 1.00465  ;  3I5°C 32.0°C 88.7-F 89.6°F 0.90620 0.90329 0.90894 0.90600 0.91165 0.90871 051441 0.91147 051712 051418 051982 051688 0.92256 0.91959 052S29 052235 052803 052506 053078 052776 053344 0.93047 053618 053318 0.93897 053606 054159 053859 05443S 054135 054706 054406 054979 0.94676 0.95250 0.94947 0.95521 055218 055797 055494 056068 055765 056341 0.96035 05661S 056312 0.9688S 0.96582 057159 056853 057429 057124 057703 057400 057976 0.97671 0.98247 057941 0.98521 0.98212 0.98794 0.98488 0.99065 0.98759 0.99338 . 0.99029 0.99609 0.99300 0.99880 0.99571 1.00156 0.99847  325°C 90.5°F  33.0°C 91.4T  3ZS°C  0.90082 0.90303 0.90576 0.90847 0.91118 051388 051659 0.91932 0.92203 0.92474 052744 0.93015 053294 053556 0.93830 0.94103 054373 054644 0.94915 0.95188 055459 0.95730 0.96003 0.96273 0.96544 0.96815 0.97088 0.97359 0.97629 0.97900 0.98176 0.98443 058717 0.98988 0.99259 0.99532  0.89735 0.90006 0.90282 0.90547 0.90818 051088 051359 051629 051900 052171 0.92441 052712 0.92982 053253 0.93544 053800 0.94071 0.94341 054612 054882 055153 055424 055694 0.95965 0.96235 0.96506 0.96776 0.97047 0.97318 0.97588 057865 058135 0.98406 0.98676 0.98947 0.99218  0.89432 0.89703 0.89976 0.90241 0.90512 0.90782 0.91053 0.91323 051594 051865 0.92135 052412 0.92676 052944 . 053215 053488 053759 0.94034 0.94300 0.94570 054841 0.95112 055382 0.95653 0.95925 0.96191 0.96461 0.96732 057003 0.97273 0.97547 0.97817 0.98088 0.98356 0.98629 0.98897  925°F  34.0°C 93.2°F  34.5°C 94.1°F  3S.0°C 9S.0°F  0.89129 0.89400 0.89671 0.89935 0.90206 0.90476 0.90747 051018 0.91288 0.91559 051829 052100 052371 0.92635 052906 053176 0.93447 053718 053988 054259 054529 0.94800 0.95071 0.95341 0.95606 . 0.95876 0.96147 0.96418 0.96688 0.96959 0.97229 057500 057771 0.98053 0.98312 0.98576  0.88821 0.89091 0.89362 0.89627 0.89897 0.90168 0.90438 0.90706 0.90976 0.91247 051517 051785 052056 0.92323 0.92591 052861 053132 053403 053670 053941 054211 0.94482 054750 0.95020 0.95288 0.95558 0.95826 0.96097 0.96367 0.96638 0.96908 0.97176 057447 0.97714 0.97986 0.98252  0.88512 0.88782 0.89053 0.89318 0.89588 0.89859 050129 0.90394 . 0.90665 0.90935 051206 051471 0.91741 052012 052276 052547 052818 053088 053353 053624 . 0.93894 0.94165 0.94429 0.94700 0.94971 0.94251 0.95506 055776 0.96047 056318 0.96588 0.968S3 0.97124 057394 0.97659 0.97929  Inches 27.56 27.64 27.72 27 JO 27.87 2755 28.03 28.11 28.19 28.27 28.35 28.43 2850 2858 28.66 2874 2842 2850 2858 29.06 29.13 29.21 29-H 2947 29.45 2943 29.61 29.69 29.76 2944 2952 30.00 30.08 30.16 30.24 3051  294  APPENDIX B ERROR A N A L Y S I S  The  following error analysis  al.[l44].  Consider a quantity  independent v a r i a b l e s x  Q = f ( X],  When t h e r e  of  3  the  n  (b.1)  n  finite  et  increments x , x ,..., x , 1  2  n  the  in Q is  T a y l o r ' s 'ser i e s  x  1 f  +Ax ,  2  , x  2  n  (b.2)  + Ax ) n  expansion  Q + AQ = f ( x  1  r  x , x , 2  1  (d t/dx2  l  x )  3  +(3f/9x )Ax +  x  2  2  Q +AQ = f ( x , + A x  By  Q which i s a function  x , X 3 , . . . ,  1 f  from M i c k l e y  x , x ,..., x )  are small  corresponding error  i s derived  2  1  n  + (3f/9x )Ax 2  ) (Ax  2 1  2  ...+  ) + ..(higher  (9f/9x )Ax n  order  n  terms) (b.3)  When A x  l f  Ax , 2  AX3,  higher order terms a r e would r e s u l t  i n a good  Ax  n  are  negligible. approximation  sufficiently  small,  The f o l l o w i n g  the  equation  295  AQ  =  (bt/dx )Ax  =  ( e r r o r caused  by Ax«)  + ( e r r o r caused  by A x )  ]  +  ]  (3f/3x )Ax 2  2  Of/3x )Ax  ...+  n  n  that i s ,  AQ  +...+  It  ( e r r o r caused  s h o u l d be n o t e d  the e r r o r  by A x ) n  that Equation  (b.4)  may  overestimate  i n v o l v e d i n t h e c a l c u l a t i o n , because i t c o n s i d e r s  only the simultaneous take  2  i n t o account  Nonetheless,  occurrence  the  error  often calculated  of t h e e r r o r s and does  possibility  estimates by t h e  known t o be conservati  of compensating  i n engineering  above p r o c e d u r e  not  effects.  analysis  are  because they  are  ve a n d h e n c e , a l l o w f o r an  additional  'margin-of-safety'.  The  above  mentioned  procedure  uncertainty associated with the R o p e r a t i n g c o n d i t i o n s o f Run from  first  R  v  v  is  used  L  v  A  -  T9 a r e u s e d  a s an e x a m p l e .  C *)/[l+IH(k °/k )]} A  analyze  value determination.  p r i n c i p l e s c a n be w r i t t e n a s :  = {lk °a (HPy  to  L  G  The R  v  296  The  u n c e r t a i n t i e s a s s o c i a t e d w i t h the estimates of kg,  a ,  H and I a r e  v  Chapter of  g e n e r a l l y i n the order  2 ) . Assuming t h a t t h e a c c u r a c y  t h e gas c o m p o s i t i o n and  C0 -NaOH s y s t e m , 2  virtually  the  free  difficult  is a  v  measurements  p r e s s u r e a r e w i t h i n ±2.5%. C0  in  2  to  f u n c t i o n of  determine  Therefore, the monitor UBC C o m p u t i n g C e n t e r ,  to  of the  the  liquid  For  phase  is  zero.  Since R  for  o f ±25 % [ 8 5 ] ( s e e  each parameter. determine  the  many  parameters,  gradients  p r o g r a m NLMON, w h i c h  i t is  analytically. i s available  at  i s u s e d t o p r o v i d e t h e v a l u e o f 3f/3x£ These v a l u e s of g r a d i e n t s a r e then  uncertainty in R  v  by means E q u a t i o n b.4.  used The  r e s u l t s a r e shown i n T a b l e B.1.  Table  Uncertainty  B.1: P r o p a g a t i o n o f E r r o r s f o r Run T 9 .  i n variable  k ±25%; k °±25%; a ±25%; H±25%; I±25%; P±25%; y ± 2 5 % G  L  v  A  Uncertainty i n R U s i n g E q . b.4 R ±95% v  v  297  As  can  be  seen f r o m T a b l e -B.1,  w i t h t h e computed v a l u e d h i g h as  95%  For  c a s e of  using laboratory  from the p r o d u c t  d e t e r m i n e d from s y s t e m must be  According  R  [ 6 2 ] and  i s d e t e r m i n e d by  R  a  within  a ,  w h i c h i s ±40  v  For  the  obtaining R i n e r t gas error be  ±10%  to  of  ±15%  neglected.  The  rotameter  i n the order w e l l as the  c o u l d be involved.  v  Before  v  k  G  as  and  k  R  v  can  be  can  be.  of  0 L  the  using  of  using  accuracy is  uncertainty.  20%.  comparison R  a ,  the  of the e r r o r s a s s o c i a t e d  with  the  i s assigned. of R  PPT,  the accuracy t h e gas  a  and  along  the  v  v  accuracy  in  i n measuring-  the  composition,  about  5 %.  Y.  The  A  the column a x i a l  i n m e a s u r i n g t h e gas To  measure  the accuracy  flow  may rate  the would  H o w e v e r , t h e e r r o r i n mass b a l a n c e  composition I f we  For  of  Since  infrared analyzer,  of ±2 %. liquid  [130], the accuracy  %.  f l o w r a t e , G j , and  composition  the  case  sum  depends o n l y on  v  a .  testing,  i n measuring the d i s t a n c e  using a  b.4  models, R  direct multiplication  f o r t h i s case i s the  and  and  Laurent  purposes, the average value  error  a  associated  matched.  is  a  of R  experimental  to Alper  obtaining  from e q u a t i o n  v  b e c a u s e a number o f p a r a m e t e r s a r e  the  acquired  of R  the u n c e r t a i n t y  measurements c o u l d  C0  2  be as  increase  a d o p t a w o r s t c a s e s c e n a r i o and  set  298  the  uncertainty  of t h e former and l a t t e r  and  ±15% r e s p e c t i v e l y ,  for  this  c a s e i s ±20 %.  uncertainties  t h e maximum e r r o r  p a r a m e t e r s t o ±5 that  could  A summary o f t h e p o t e n t i a l  i n determining the R  v  Determination of specific absorption  First  principles  Laboratory PPT  models  rate  occur maximum  p r o v i d e d by T a b l e B.2.  T a b l e B.2: E s t i m a t e s o f p o t e n t i a l u n c e r t a i n t i e s  %  in R  P o t e n t i a l max.  95  %  40  %  20  %  v  error  APPENDIX C COMPUTER PROGRAM L I S T I N G S  Cl.  C C C C Q  PROGRAM FOR P R E D I C T I N G C Q ~ A M P 2  SOLUBILITY  PRIDICT LOADING *******riew fitted for p K l MODIFIED FROM SOL9/5 (PRIDICTION OF PC02) SOLUBILITY CALCULATION FOR C02 - A M P SYSTEM >>>> C A L C U L A T E ======= ********* ******************************* IMPLICIT REAL*8(A-H,0-Z) DIMENSION X(10),F(10),AJINV(10,10),W(500),IPERM(20) COMMON CK1,CK3,CK4,CK5,CK6 COMMON AMP,T,PC02,ALFA DATA DATA DATA DATA  AAl,ABl/-2.3091D+3,-4.9828D-01/ ACl,ADl/7.0850E+4,3.8803D+2/ AEl,AFl/6.3899D+00,9.5221D-2/ AG1/-3.8508D-2/  D A T A A3,B3,C3/-241.818D0, 298.253D3, -148.528D6/ D A T A D3.E3/332.648D8, -282.394D10/ D A T A A4,B4,C4/39.5554D0, -987.9D2, 568.828D5/ D A T A D4.E4/-146.451D8, 136.146D10/ D A T A A5,B5,C5/-294.74D0, 364.385D3, -184.158D6/ D A T A D5.E5/415.793D8, -354.291D10/. D A T A A6,B6,C6/22.2819D0, -138.306D2, 691.346D4/ D A T A D6.E6/-155.895D7, 120.037D9/ AVE=0. NP=60 C ** R E A D D A T A FROM K l - D A T A / 5 NE =8 DO 5 I=1,NP READ (5,10) AMP,T,ALFA,PC02,CK1 10 F O R M A T (5D12.4) C WRITE (6,12) CK1 C 12 F O R M A T (' DATA OF K l = \D12.4) C C C A L C U L A T E CONSTANTS ~ CK3 = DEXP(A3 + B3/T +(C3/(T**2)) +(D3/(T**3)) +(E3/(T**4))) CK4 = DEXP(A4 + B4/T +(C4/(T**2)) +(D4/(T**3)) +(E4/(T**4))) CK5 = DEXP(A5 + B5/T +(C5/(T**2)) +(D5/(T**3)) +(E5/(T**4)))  CK6 = DEXP(A6 + B6/T +(C6/(T**2)) +(D6/(T**3)) +(E6/(T**4))) CK6 = CK6/(760./101.15) C02=PC02/CK6 CK1 =AA1 + AB1*T + (AC1/(T**1)) + (ADl*DLOG(T)) >+ AE1*(C02) +(AF1*DL0G(C02)) +AG1*(AMP) CK1 = 10.**CK1 C WRITE (6,11) CK1 C 11 . F O R M A T ( ' FITTED KI =  \D12.4)  C SET INITIAL V A L U E C X(1)=H+, X(2)=RRNH, X(3)=RRNH2+, X(4)=HC03C X(5)= C02, X(6)=OH-, X(7)=C03-, X(8)=ALFA (CAL) C X A L F A = 0.75 IF(T.GT.(273.+60.)) XALFA=.75 IF(T.GT.373.) XALFA=.20  C C C C C C C C C C C 50  X(l)= l.D-8 X(2)= AMP*(1.-XALFA) X(3)= A M P * X A L F A X(4)= A M P * X A L F A X(5)= X(1)*X(4)/CK3 X(6)= CK4/X(1) X(7)= l.D-5 X(8)= X A L F A X(l)= l.D-8 X(5)= PC02/CK6 X(4)= CK3*X(5)/X(1) X(6)= CK4/X(1) X(7)= l.D-4 X(3)= X(4) X(2)= CK1*X(3)/X(1) X(8)= (X(5)+X(4)+X(7))/AMP WRITE (6,50) X(1),X(2),X(3),X(4),X(5),X(6),X(7),X(8) F O R M A T (/'INIT= '/.8D9.2)  C SET INPUT FOR NDINVT C DSTEP=l.D-7 DMAX = 10. A C C = l.D-20 M A X F U N = 15000 LOG = 00 E X T E R N A L FCN C CALL QNEWT  CALL QNEWT(NE,X,F,NE,AJINV,DSTEP,DMAX,ACC,MAXFUN,LOG,W,IPERM, > FCN.&70) C C PRINT XI TO X9 C EER = (ALFA-X(8))*100/ALFA WRITE (6,52) AMP,T,PC02,ALFA,X(8),EER A V E = A V E +DABS(EER) 52 F O R M A T (6D12.4) 5 CONTINUE  75  WRITE (6,75) F O R M A T ( AMP',9X,'TEMP',9X,'PC02',9X, ALFA',8X,'CAL.PC02') ,  ,  AVE = AVE/NP WRITE (6,85) A V E 85 F O R M A T (/' A V E ERR = ',F9.3) STOP 70 WRITE (7,100) 100 F O R M A T ('?? ERR FORM NDINVT') STOP 1 END C C SUBROUTINE F C N C SUBROUTINE FCN(X.F) IMPLICIT REAL*8(A-H.O-Z) DIMENSION X(1),F(1) COMMON CK1,CK3,CK4,CK5,CK6 COMMON AMP,T,PC02,ALFA C C3  DO 3 IJ = 1,8 IF (X(IJ).LT.l.D-20) X(IJ)=l.D-20 F(l) = X(3) + X(l) - X(6) - X(4) - 2 *X(7) F(2) = X(8)*AMP - X(5) - X(4) - X(7) F(3) = A M P - X(2) - X(3) F(4) = PC02 - (CK6)*X(5) F(5) = CK5 - (X(1)*X(7)/X(4)) F(6) = CK4 - (X(1)*X(6)) F(7) = CK3 - (X(1)*X(4)/X(5)) F(8) = CK1 - (X(1)*X(2)/X(3)) RETURN END  _  C2.  PROGRAM FOR P R E D I C T I N G (NaOH-CQ )  COLUMN PERFORMANCE  F O R RUN T 9  2  C RUN-T9 (RUN44) C FULL SCALE RUN ********** C IMPLICIT REAL*8(A-H,J-M,0-Z) DIMENSION PYA(900),PYS(900),PCR(900),T(900),HT(900) DIMENSION PTG(900),PEG( 15),PEC( 15),PET( 15),PHT(20) C WRITE(6,321) 321 F O R M A T ( / ' **** RUN # (T9) 44 ****'/  > C 323  •===================./)  WRITE(7,323) F O R M A T ( / ' **** RUN # (T9) 44 ****'/ > . _ _ .) = = = = = = = =  C  c  C C C C C C  C C C C C C  = = =  = = =  = = =  CALCULATION OF C02 - AMINE SYSTEM. 1. ASSUME T H E T E M P . AND SOLVENT V A P O R CONCENTRATION (YS) OF T H E O U T L E T GAS . TG(C), TGK(K), YS(MOLE FRACTION) T G O U T = 15.0 Y S O U T = 0.031 - 2. C O M P U T E T H E ENTHALPIES OF T H E ENTERING STREAMS AND T H E O U T L E T GAS . BY T H E MATERIAL AND E N T H A L P Y BALANCES FOR T H E ENTIRE TOWER, C O M P U T E T H E O U T L E T LIQUID R A T E , COMPOSITION AND T E M P E R A T U R E .  NDUM=0 C ? C C P = T O T A L PRESSURE. P = 1.0 C CONC. IN LIQUID = G - M O L / C C . C CRIN = 2.00 CPIN = (2.00-CRIN)/2. LMIN= (1.00)*(1820./(60*80)) TLIN = 15.0 GB =1.475E-3 SYAIN = 18.45/100. YAIN = SYAIN/(1.-SYAIN)  YBIN = 1.0 YSIN = 0.001 TGIN =15. CROUT = 0.37 C P O U T = (2.0-CROUT)/2. C T L O U T IS ASSUMED FROM OVERALL ENERGY BALANCE. T L O U T = 35.0 SYAOUT = 1.00/100 YAOUT= SYAOUT/(l.-SYAOUT) Y B O U T = 1. C YSOUT AND T G O U T A R E ASSUME AS A B O V E C C C  STEP BY STEP CALCULATIONS NOW BEGIN FROM T H E B O T T O M OF T H E TOWER . CR = CROUT CP = CPOUT TL = TLOUT L M = LMIN+0.0005  Y A = YAIN Y B = YBIN YS = YSIN T G = TGIN Z = 0. C GBin and G'Bout are the same. C . . C - 3. OBTAIN ALL T H E NECESSARY PHYSICAL AND CHEMICAL PROPERTIES C OF T H E GAS AND LIQUID . C E G . VISCOSITY, DENSITY, H E A T CAPACITY, T H E R M A L CONDUCTIVITY, C • DIFFUSIVITIES, VAP O R PRESSURE O F SOLVENT S , C CHEMICAL EQUILIBRIUM CONSTANT Kc , C FORWARD REACTION R A T E CONSTANT K2 . C C SEE T A B L E I P.356 C N =1 NOUT = 1 NSET = 900 C ???? C 300 STOI = 2. CPA = 8.8 CPS = 8.1 CPB = 7.0 HLH20 = 10761 CL = 1.0 PL = 1.0  HR = -24400.  T L K = TL+273.15 DA = (1.65D-5)*(((647.3-298.)/(647.3-TLK))**3) DR = DA/1.7 C C C  T H E REACTION R A T E CONSTANT K2.  ASI = CR + (((2.*CP)+(CP*4.))/2) ALK2 = 11.895 - (2382/TLK) +(0.221*ASI)-(.016*(ASI**2)) K2 = 10 **(ALK2) C K2 = L / G - M OL.SEC. C C T H E SOLUBILITY OF GAS IN SOLUTION. C ( SEE COMMENTS ON P.356 ) C HW= 10 **(9.1229-(.059044*TLK)+(7.8857D-5*(TLK**2))) AHG = 0.124515-(.00047*(TLK)) SHI=(CR*(.091+.066+AHG))+(((2.*CP-l-CP*4.)/2)*(.09H-.066-|-AHG)) H = HW*(10.**(-SHI)) C WRITE (7,221) DA,ASI,K2,HW,H C221 F O R M A T (/5D10.3) C C 4. ESTIMATE KLA, K G A , KGS, HGA FROM T H E AVAIBLE CORRELATIONS. C SEE T A B L E II P.356 C A = 1.500 KLA = (2.6*DA)**(.5) K G A = 3.2 D-5 KGS = 3.2 D-5 HGA = 2.478 D-3 C C STORE D A T A  C C C  C  PYA(N)=YA PYS(N)=YS PCR(N)=CR T(N) = T L PTG(N) = T G HT(N) = Z 5. ASSUME PAI = PA PA = P*(YA/(YA+YS+YB)) PAI =PA CAI = H*PAI  C 200  C C C C C C C C C  REAL*8 M,M2  IF(CR.LT.0.0005) E = l . IF(CR.LT.0.0005) GOTO201 M2 = K2*CR*DA/(KLA**2) E l = DSQRT(M2)/DTANH(DSQRT(M2)) EI = 1. + ((CR*DR)/(2.*CAI*DA)) EI = (DSQRT(DA/DR))+(CR/(2.*CAI))*(DSQRT(DR/DA)) ASSUME LIQUID HOLD UP = 5% OF T O T A L V A L U E . HU = 0.05 X X X = HU*K2*CR/(KLA*A) IF (XXX.LT.20.) GO T O 550  EA = l./((EI-l.)**1.35) EB = l./((El-l.)**1.35) E=1.+(1./((EA+EB)**(1./1.35))) 201  CONTINUE  C C550 WRITE (6,555) C555 F O R M A T (IX,' !!! E O U T O F F RANGE.') C GOTO 900 CC C560 WRITE (6,565) C565 F O R M A T (/' !! E » 1. ???'/) C C C H A C K E VALUE? C WRITE (6,566) C566 F O R M A T (/' CHACK E CALCULATION. '/) C WRITE (6,567)M2,M,SRM C567 F O R M A T (' '.F15.4/F15.4/F15.4/) C WRITE (6,568)Q,QM,XXX,E C568 F O R M A T (' ',F15.4/F15.4/F15.4/,' . . » E',F15.4/) C C GO TO 900 C C C C  6. ASSUME C A E = 0.0 R = (E*KLA*PA*H*l.D-3)/(l.+((E*KLA*H)*I.D-3)/(KGA)) CAINEW = (PA*H)-(R*H/KGA) PAIN = CAI/H  C  IF (DABS(CAINEW-CAI).LE.DABS(0.00010*(CAINEW+CAI))) GOTO 700 C  C C C C 700  CAI=CAINEW GO T O 200 7. C O M P U T E DYA/DZ, DYS/DZ, D T G / D Z , AND D T G / D Z FROM T H E EQ.S 30,31,32,..29) PSI = 0.90*( 2.7182818**(16.5362-(3985.44/(TLK-38.9974))))/ > 101.13 YSI = PSI/(P-PAIN-PSI) YAI = PAIN/(P-PAIN-PSI) PS =P*(YS/(YA+YB+YS)) DYADZ = -KGA*A*(PA-PAIN)/GB DYSDZ = -KGS*A*(PS-PSI)/GB HDGA= (-l.*GB)*(CPA*DYADZ + CPS*DYSDZ)/ > (1-DEXP(GB*(CPA*DYADZ + CPS*DYSDZ)/HGA)) DTGDZ = -HDGA*(TG-TL)/(GB*(CPB+YA*CPA+YS*CPS ))  C C REF. T E M P . TO = 25 C. TO = 25. DTLDZ = (l./(LM*CL))*((GB*(CPB+YA*CPA+YS*CPS)*DTGDZ) > + (GB*(CPS*(TG-T0) + HLH20 )*DYSDZ) > + (GB*(CPA*(TG-T0) - HR)*DYADZ)) C C 8. CHOOSE A SUITABLY SMALL V A L U E OF DYA , C A N INCREMENT OF GAS COMPOSITION, SO T H A T T H E C GRADIENTS D Y A / D Z , D Y S / D Z , D T G / D Z , AND DTL/DZ C WILL NOT CHANGE T O O GREATIY . C DELYA = -0.00025*4. DELZ = D E L Y A / D Y A D Z C C WRITE(6,10) CR,PA,PAIN,PSI,Z,DELZ,E C10 FORMAT(' ',F10.6,'(CR)',F10.6, (PA)',F10.6, (PAI)*, C > F12.4,'(PSI)\F12.4,'(DZ)',F12.4,'(Z) ,F12.4, (E) ) C C WHERE Z=0. FOR T H E B O T T O M OF T H E TOWER . C Z= Z+ DELZ C C 9. C O M P U T E T H E CIRCUMSTANCES A T Z-NEXT . C YA = Y A + DELYA YS = YS + DELZ*DYSDZ T G = T G + DELZ*DTGDZ T L = T L + DELZ*DTLDZ LMOLD = LM LM = LM + GB*DELZ*(DYADZ+DYSDZ)*29. C ,  ,  ,  ,  ,  CR=(((LMOLD*CR/1000.) - STOI*GB*DELYA)/LM)*1000. CP=(((LMOLD*CP/1000.) + GB*DELYA)/LM)*1000. C C PRINT SOME RESULTS C NIN = N/50 IF(NIN.GE.NOUT) CALL CHACK (NIN,CR,CP,LM,TL, > YA,YB,YS,TG,Z,NOUT) IF(NDUM.EQ.0.AND.Z.GT.110.) CALL CKOUT(Z,CR,YA,TL,N,NDUM) IF(Z.GT.110..AND.Z.LT.220.) GOTO 850 IF(NDUM.EQ.1.AND.Z.GT.220.) CALL CKOUT(Z,CR,YA,TL,N,NDUM) IF(Z.GT.220..AND.Z.LT.330) GOTO 850 IF(NDUM.EQ.2.AND.Z.GT.330.) C A L L CKOUT(Z,CR,YA,TL,N,NDUM) IF(Z.GT.330.AND.Z.LT.435.) G O T O 850 IF(NDUM.EQ.3.AND.Z.GT.435.) CALL CKOUT(Z,CR,YA,TL,N,NDUM) IF(Z.GT.440..AND.Z.LT.550) GOTO 850 IF(NDUM.EQ.4AND.Z.GT.550.) C A L L CKOUT(Z,CR,YA,TL,N,NDUM) IF(Z.GT.550..AND.Z.LT.650) GOTO 850 850  CONTINUE IF(YA.LT.YAOUT) CALL CKOUT(Z,CR YA,TL,N,NDUM) 1  C C C C  C  10. R E P E A T STEP 3 T O 9 UNTIL Y A FOR T H E O U T L E T GAS IS REACHED . IF(YA.LT.YAOUT) GO T O 900 N=N+1 IF(N.GT.NSET) GO T O 900  WRITE(8,1111) Z,PA,CR,TL,TG,E 1111 FORMAT(6F11.6) C GOTO 300 C C C 11. CHECK T H E ASSUMPTION OF STEP" 1. C IF NOT MATCHED, IT M A Y B E APPROPRIATE GUESS FOR . C T H E N E X T ITERATION . HOWEVER, IF T H E SOLUTION IS FOUND C T O B E INSENSITIVE T O T H E ASSUMED VALUES OF T G AND YS C (THROUGH T H E B A C K CALCULATION OF O U T L E T LIQUID T E M P . C FROM AN OVERALL E N T H A L P Y BALANCE) FURTHER ITERATION C WILL NOT BE REQUIRED . C C C 900 WRITE(6,905) 905 F O R M A T ( / ' ***** T H E END CONDITION *****'/) WRITE(6,910) CRIN 910 F O R M A T ( / ' INLET CONCN. OF M E A \F10.5,' G-MOL/L')  WPJTE(6,915) CPIN F O R M A T C INLET CONCN. OF PROD. \F10.5,* G-MOL/L') WRITE(6,920) LMIN 920 F O R M A T C INLET L. MOLAR VEL. ',F10.5,' G-MOL/SEC.CM2') WRITE(6,925) TLIN 925 F O R M A T C INLET LIQUID T E M P . \F10.5,' C )  915  WRITE(6,930) CROUT F O R M A T ( / ' OUTLET CONCN. OF MEA \F10.5,' G-MOL/L') WRITE(6,935) CPOUT 935 F O R M A T C O U T L E T CONCN. OF PROD. \F10.5,' G-MOL/L') WRITE(6,945) T L O U T 945 F O R M A T C OUTLET LIQUID T E M P . \F10.5,' C )  930  WRITE(6,950) GB F O R M A T ( / ' INLET AIR MOL. V E L . ',F10.5,'G-MOL/SEC.CM2') WRITE(6,955) YAIN 955 F O R M A T C INLET MOL FRAC. OF C02 \F10.5) WRITE(6,960) YBIN 960 F O R M A T C INLET MOL FRAC. OF AIR \F10.5) WRITE(6,965) TGIN 965 F O R M A T C INLET GAS T E M P . \F10.5,' C )  950  WRITE(6,970) Y A O U T F O R M A T ( / ' OUTLET MOL FRAC. OF C02 '.F10.5) WRITE(6,975) YBOUT 975 F O R M A T C O U T L E T MOL F R A C . OF AIR \F10.5) WRITE(6,980) YSOUT 980 F O R M A T C OUTLET MOL F R A C . OF H20 \F10.5) WRITE(6,985) T G O U T 985 F O R M A T C OUTLET GAS T E M P . \F10.5,' C ) 970  990  WPJTE(6,990) F O R M A T ( / ' *** >> CALCULATION RESULTS')  991  WRITE(6,991) CR F O R M A T ( / ' INLET CONCN. OF MEA \F10.5,' G-MOL/L')  WRITE(6,992) CP F O R M A T C INLET CONCN. OF PROD. \F10.5,' G-MOL/L') WRITE(6,993) LM 993 F O R M A T C INLET L. MOLAR V E L . \F10.5,' G-MOL/SEC.CM2') WRTTE(6,994) T L 994 F O R M A T ( ' INLET LIQUID T E M P . \F10.5,' C )  992  WRITE(6,995) Y A F O R M A T ( / ' OUTLET MOL FRAC. OF C02 '.F10.5) WRTTE(6,996) YB 996 F O R M A T C OUTLET MOL FRAC. OF AIR '.F10.5) 995  WRJTE(6,997) YS FORMAT(' O U T L E T MOL FRAC. OF H20 \F10.5) WRITE(6,998) T G 998 F O R M A T f O U T L E T GAS T E M P . \F10.5,' C ) 997  999  WRITE(6,999) Z F O R M A T C T H E T O T A L HEIGHT ',F10.5,' CM.'/)  C SCALING DO 1 I=1,N HT(I) = 2. + (HT(I)/(1.*100.)) PMIX = l.+PYS(I) +PYA(I) PMLXX = 1. + PYA(I) PYA(I) = 1. +((PYA(I)/(PMIXX))/0.03) PYS(I) = 1. +((PYS(I)/(PMIX))/0.03) PCR(I) = 1. + (PCR(I)/.6) T(I) = 1. + (T(I)*5./50.) PTG(I) = 1. + (PTG(I)*5./50.) 1 CONTINUE C PLOTTING CALL CALL CALL CALL CALL  AXIS(1.,.5,'P. CO2',-6,7.,0.,0.,0.03) AXIS(1.,1.,'P. H2O',-6,7.,0.,0.,0.03) AXIS(1.,1.5,'MEA (MOL/L)',-11,7.,0.,0.,0.6) AXIS(1,2.,'TEMP. (C)',-9,7.,0. 0.,10.) AXIS(1,2.,'HEIGTH (M)',10,7.,90,0.,l.)  CALL CALL CALL CALL CALL CALL CALL CALL CALL CALL CALL CALL CALL CALL CALL CALL CALL CALL CALL CALL CALL CALL CALL  PLOT(l.,2.,3) PLOT(2,2.,2) PLOT(2.,9.,2) PLOT(3.,9.,2) PLOT(3.,2.,2) PLOT(4.,2.,2) PLOT(4.,9.,2) PLOT(5.,9.,2] PLOT(5.,2.,2) PLOT('6.,2.,2; PLOT(6.,9.,2; PLOT(7.,9.,2; PLOT(7.,2.,2; PLOT(8.,2.,2; PLOT(8.,9.,2; PLOT(7.,9,2; PLOT(8.,3.,3; PLOT(l.,3.,2; PLOT(l.,4.,2; PLOT(8.,4.,2^ PLOT(8.,5.,2^ PLOT(l.,5.,2 PLOT(l.,6.,2  1  310  C A L L PLOT(8.,6.,2) C A L L PLOT(8.,7.,2) C A L L PLOT(l.,7.,2) C A L L PLOT(l.,8.,2) C A L L PLOT(8.,8.,2) C A L L PLOT(8.,9.,2) C A L L PLOT(l.,9.,2) C A L L PLOT(l.,2.,3) DO 2 I=1,N C A L L SYMBOL(PYA(I),HT(I) .010,0,0.,-2) CONTINUE 1  2  C A L L PLOT(l.,2.,3)  3  DO 3 I=1,N C A L L SYMBOL(PYS(I),HT(I),.010,l,0.,-2) CONTINUE C A L L PLOT(l.,2.,3) DO 4 I=1,N C A L L SYMBOL(PCR(I),HT(I),.010,2,0. 2) CONTINUE r  4  C A L L PLOT(l.,2.,3)  5  DO 5 I=1,N CALLSYMBOL(T(I),HT(I),.010,ll,0.,-2) CONTINUE C A L L PLOT(l.,2.,3)  6  DO 6 1=1,N C A L L SYMBOL(PTG(I),HT(I),0.01,5,0.,-2) CONTINUE CALL CALL CALL CALL  SYMBOL(2.0,10.0,0.08,0,0.,-1) SYMBOL(2.2,10.0,0.08,'P-CO2 (ATM)',0.,11) SYMBOL(3.5,10.,0.08,1,0.,-1) SYMBOL(3.7,10.,0.08,'P-H2O (ATM)',0.,11)  CALL CALL CALL CALL CALL CALL  SYMBOL(5.0,10.0,0.08,2,0.,-1) SYMBOL(5.2,10.0,0.08,*NAOH (MOL/L)',0.,12) SYMBOL(2.0,9.7,0.08,11,0.,-1) SYMBOL(2.2,9.7,0.08,'LIQUID T E M P . (C)',0.,16) SYMBOLls.S^J.O.OS.S.O.,-!)  SYMBOL(3.7,9.7,0.08,'GAS T E M P . (C)',0.,13)  CALL  PDATA(PEG,PEC,PET,PHT,NEX)  DO 10011=1,NEX EG = 1.+ (PEG(I)/0.03) E C = 1. + (PEC(I)/.6) E T = l.+(PET(I)/10.) EH = 2.+(PHT(I)/100.) CALL SYMBOL(EG,EH,.12,0,0.,-1) CALL SYMBOL(EC,EH,.12,2,0.,-1) CALL SYMBOL(ET,EH,.12,11,0.,-1) 1001 CONTINUE  CALL SYMBOL(4,9.25,.25,'RUN# T09',0.,8) CALL PLOTND STOP END Q  C C C  **********************************************  SUBROUTINE  CHACK(NIN,CR,CP,LM,TL,YA,YB,YS,TG,Z,NOUT)  IMPLICIT REAL*8(A-M.O-Z)  990  WRITE(6,990) F O R M A T ( / ' :::: INTERMEDIAD CALCULATION RESULTS')  991  WRITE(6,991) CR F O R M A T ( / ' CONCN. OF MEA \F10.5,' G-MOL/L')  WRITE(6,992) CP FORMATC CONCN. OF PROD. ',F10.5,' G-MOL/L') WRITE(6,993) LM 993 FORMATC LIQUID MOLAR VEL. \F10.5,' G-MOL/SEC.CM2') WRITE(6,994) T L 994 FORMATC LIQUID T E M P . ',F10.5,' C ) 992  WRITE(6,995) Y A F O R M A T ( / ' MOL FRAC. OF C02 \F10.5) WRITE(6,996) YB 996 FORMATC MOL FRAC. OF AIR \F10.5) WRITE(6,997) YS 997 FORMATC MOL FRAC. OF H20 \F10.5) WRITE(6,998) T G 998 FORMATC GAS T E M P . \F10.5,' C )  995  999  WRITE(6,999) Z FORMATC T H E HEIGHT \F10.5,' CM.'/) NOUT = NOUT + 1  c  RETURN END  Q ************************************************* C C C 990  SUBROUTINE CKOUT(Z,CR,YA,TL,N,NDUM) IMPLICIT REAL*8(A-M,0-Z) WRITE(7,990) F O R M A T ( / ' :::: INTERMEDIAL CALCULATION RESULTS')  WRITE(7,999) Z F O R M A T ( / ' T H E HEIGHT ',F10.5,' CM.'/) PYA = 100.*YA/(1.+YA) WRITE( 7,995) P Y A 995 F O R M A T ( ' C02 CONC. (%) '.F10.5) WRITE(7,991) CR 991 F O R M A T ( ' CONCN. OF NAOH ',F10.5,' G-MOL/L') 999  994 C  Q  WRITE(7,994) T L F O R M A T ( ' LIQUID T E M P . ',F10.5,' C ) NDUM=NDUM+1 RETURN END **************************************************  SUBROUTINE PDATA(EG,EC,ET,EH,NEX) IMPLICIT REAL*8(A-H.O-Z) DIMENSION EG(20),EC(20),ET(20),EH(20),G(20),C(20),T(20),H(20) NEX=5  10  DATA H/0.000,110.,220.,330.,435./ D A T A G/.1845,.1155,.0580,.0265,.0100/ D A T A C/.41,1.08,1.625,1.900,2.00/ DATA T/35.0,29.0,22.0,17.0,15.0/ DO 10 1=1,NEX EH(I)=H(I) EG(I)=G(I) EC(I)=C(I) ET(I)=T(I) RETURN END  313  C3. PROGRAM FOR P R E D I C T I N G (MEA-CQ ) C  COLUMN PERFORMANCE  F O R RUN T22  2  C RUN-T22(RUN41) C FULL SCALE RUN ********** C IMPLICIT REAL*8(A-H,J-M,0-Z) DIMENSION PYA( 1900),PYS( 1900),PALF( 1900),T( 1900),HT( 1900) DIMENSION PTG(1900),PEG(15),PEC(15),PET(15),PHT(20) C WRITE(6,321) 321 F O R M A T ( / ' ***** RUN # (T22)41 ****'/ C 323 C C C C C C C C  C C C C C C  >  •-===================7)  WRITE(7,323) F O R M A T ( / ' **** RUN # (T22)41  >  ****7  '===================•)  CALCULATION OF C02 - AMINE SYSTEM. 1. ASSUME T H E T E M P . AND SOLVENT V A P O R CONCENTRATION (YS) OF T H E O U T L E T GAS . TG(C), TGK(K), YS(MOLE FRACTION) T G O U T = 19.0 YSOUT = 0.031 2. C O M P U T E T H E ENTHALPIES OF T H E ENTERING STREAMS AND T H E O U T L E T GAS . B Y T H E MATERIAL AND E N T H A L P Y BALANCES FOR T H E ENTIRE TOWER, C O M P U T E T H E O U T L E T LIQUID R A T E , COMPOSITION AND T E M P E R A T U R E .  NDUM=0 C ? C C P = T O T A L PRESSURE. P = 1.0 C CONC. IN LIQUID = G - M O L / C C . C C T O T = 3:00 ALFIN= .000 LMIN= (1.00)*(1270y(60*80)) TLIN = 19.0 GB =1.475E-3 SYAIN = 19.10/100. YAIN = SYAIN/(1.-SYAIN)  YBIN = 1.0 YSIN = 0.001 TGIN =15. A L F O U T = 0.443 C T L O U T IS ASSUMED FROM OVERALL ENERGY BALANCE. T L O U T = 47.0 SYAOUT = 0.05/100 YAOUT= SYAOUT/(l.-SYAOUT) Y B O U T = 1. C Y S O U T AND T G O U T A R E ASSUME AS A B O V E C C C  STEP BY STEP CALCULATIONS NOW BEGIN FROM T H E B O T T O M OF T H E TOWER . ALF = ALFOUT TL = TLOUT LM = LMIN+0.0005  Y A = YAIN YB = YBIN YS = YSIN T G = TGIN Z = 0. C GBin and GBout are the same. C C 3. OBTAIN ALL THE NECESSARY PHYSICAL AND CHEMICAL PROPERTIES C OF T H E GAS AND LIQUID . C EG. VISCOSITY, DENSITY, H E A T CAPACITY, T H E R M A L CONDUCTIVITY, C DIFFUSIVITIES, V A P O R PRESSURE OF SOLVENT S , C CHEMICAL EQUILIBRIUM CONSTANT Kc , C FORWARD REACTION R A T E CONSTANT K2 . C C SEE T A B L E I P.356 C N =1 . NOUT = 1 NSET = 1900 C ???? C 300 STOI = 2. CPA = 8.8 CPS = 8.1 CPB = 7.0 HLH20 = 10761 CL = 1.0 PL = 1.0 HR = -20166.  T L K  = TL+273.15  DA = (0.64)*(2.0D-5)*(((647.3-298.)/(647.3-TLK))**3) DR = (0.80D-5)*(((647.3-298.)/(647.3-TLK))**3) C C C  T H E REACTION R A T E CONSTANT K2. ASI=ALF*CTOT IF(ALF.GE.0.5) ASI=0.5*CTOT  ALK2 = 11.069 - (2142.34/TLK) K2 = 10.**(ALK2) C K2 = L / G - M OL.SEC. C C T H E SOLUBILITY OF GAS IN SOLUTION. C ( SEE COMMENTS ON P.356 ) C HW= 10.**(9.1229-(.059044*TLK)+(7.8857D-5*(TLK**2))) A H G = 0.124515-(.00047*(TLK)) SHI=(.031+.021+.021+AHG)*ASI H = HW*(10 **(-SHI)) C C A L . F R E E AMINE C A L L SOL(TLK,CTOT,ALF,PEC02) CAB=H*PEC02 CR = CTOT-(2 *CTOT*ALF)+CAB C WRITE (7,221) DA,ASI,K2,HW,H C221 F O R M A T (/5D10.3) C C 4. ESTIMATE KLA, K G A , KGS, HGA FROM T H E AVAIBLE CORRELATIONS. C SEE T A B L E II P.356 C A = 1.350 K L A = (2.4*DA)**(.5) K G A = 3.2 D-5 KGS = 3.2 D-5 HGA = 2.478 D-3 C C STORE D A T A PYA(N)=YA PYS(N)=YS PALF(N)=ALF T(N) = T L PTG(N) = T G HT(N) = Z C C  5. ASSUME PAI = PA  PA : PAI  C  CAI  P*(YA/(YA+YS+YB)) PA H*PAI  REAL*8 M,M2  C 200  C C C C C C C C C  IF(CR.LT.0.00005) E = l . IF(CR.LT.0.00005) GOTO201 M2 = K2*CR*DA/(KLA**2) E l = DSQRT(M2)/DTANH(DSQRT(M2)) EI = 1. + ((CR*DR)/(2.*CAI*DA)) EI = (DSQRT(DA/DR))+(CR/(2.*CAI))*(DSQRT(DR/DA)) ASSUME LIQUID HOLD UP = 5% OF T O T A L V A L U E . HU = 0.05 X X X = HU*K2*CR/(KLA*A) IF (XXX.LT.20.) GO TO 550  EA = l./((EI-l.)**1.35) EB = l./((El-l.)**1.35) EIR=1.+(1./((EA+EB)**(1./1.35))) E=EIR*(CAI-CAB)/CAI IF(E.LT.l.O) WRITE(6,565) 565 F O R M A T (/' !! E < 1. ???'/) C IF(E.LT.l.O) E = l . 201 CONTINUE C C550 WRITE (6,555) C555 F O R M A T (IX,' !!! E OUT O F F RANGE.') C G O T O 900 CC C560 WRITE (6,565) C565 F O R M A T (/' !! E < 1. ???'/) C C C H A C K E VALUE? C WRITE (6,566) C566 F O R M A T (/' CHACK E CALCULATION. '/) C WRITE (6,567)M2,M,SRM C567 F O R M A T (' '.F15.4/F15.4/F15.4/) C WRITE (6,568)Q,QM,XXX,E C568 F O R M A T (' '.F15.4/F15.4/F15.4/,' . . » E',F15.4/) C C GO TO 900 C  C C  C C  C C C C 700  6. CAL. ABSORPTION R A T E R = ((E*KLA*l.D-3)*(H*PA-CAB))/(l.+((E*KLA*H)*l.D-3)/(KGA)) CAINEW = (PA*H)-(R*H/KGA) PAIN = CAI/H IF (DABS(CAINEW-CAI).LE.DABS(0.00010*(CAINEW+CAI))) GOTO 700 CAI=CAINEW GO T O 200 7. C O M P U T E D Y A / D Z , DYS/DZ, D T G / D Z , AND D T G / D Z FROM T H E EQ.S 30,31,32,..29) PSI = 0.90*( 2.7182818**(16.5362-(3985.44/(TLK-38.9974))))/ > 101.13 YSI = PSI/(P-PAIN-PSI) YAI = PAIN/(P-PAIN-PSI) PS =P*(YS/(YA+YB+YS)) DYADZ = -KGA*A*(PA-PAIN)/GB DYSDZ = -KGS*A*(PS-PSI)/GB HDGA= (-1 *GB)*(CPA*DYADZ + CPS*DYSDZ)/ > (1-DEXP(GB*(CPA*DYADZ + CPS*DYSDZ)/HGA)) DTGDZ = -HDGA*(TG-TL)/(GB*(CPB+YA*CPA+YS*CPS  )) C C REF. T E M P . TO = 25 C. TO = 25. DTLDZ = (l./(LM*CL))*((GB*(CPB+YA*CPA+YS*CPS)*DTGDZ) > + (GB*(CPS*(TG-T0) + HLH20 )*DYSDZ) > + (GB*(CPA*(TG-T0) - HR)*DYADZ)) C C 8. CHOOSE A SUITABLY SMALL V A L U E OF DYA , C A N INCREMENT OF GAS COMPOSITION, SO T H A T T H E C GRADIENTS D Y A / D Z , D Y S / D Z , D T G / D Z , AND D T L / D Z C WILL NOT C H A N G E TOO GREATIY . C D E L Y A = -0.00025*2. IF(ALF.GT.0.4) D E L Y A = -0.00005*2. DELZ = D E L Y A / D Y A D Z C C WRITE(6,10) ALF,PA,PAIN,PSI,Z,DELZ,E C10 F O R M A T C ,F10.6,'(ALF)',F10.6,'(PA)',F10.6, (PAI)', C > F12.4 (PSI)',F12.4 (DZ) F12.4 (Z)',F12.4, (E)') C C WHERE Z=0. FOR T H E B O T T O M OF T H E TOWER . C Z= Z+ DELZ C ,  1  ,  ,  1  ,  ,  1  1  ,  ,  C C  C  9. COMPUTE T H E CIRCUMSTANCES A T Z-NEXT . Y A = Y A + DELYA YS = YS + DELZ*DYSDZ T G = T G + DELZ*DTGDZ T L = T L + DELZ*DTLDZ LMOLD = LM LM = LM + GB*DELZ*(DYADZ+DYSDZ)*29.  CR=(((LMOLD*CR/1000.) - STOI*GB*DELYA)/LM)*1000. CP=(((LMOLD*CP/1000.) + GB*DELYA)/LM)*1000. ALF=(CTOT-CR+CAB)/(CTOT*2.)  C C PRINT SOME RESULTS C NIN = N/100 IF(NIN.GE.NOUT) CALL C H A C K (NIN,ALF,LM,TL, > YA,YB,YS,TG,Z,NOUT)  IF(NDUM.EQ.0.AND.Z.GT.110.) CALL CKOUT(Z,ALF,YA,TL,N,NDUM) IF(Z.GT.110..AND.Z.LT.220.) GOTO 850 IF(NDUM.EQ.1.AND.Z.GT.220.) CALL CKOUT(Z,ALF,YA,TL,N,NDUM) IF(Z.GT.220..AND.Z.LT.33O) GOTO 850 IF(NDUM.EQ.2.AND.Z.GT.330.) CALL CKOUT(Z,ALF,YA,TL,N,NDUM) IF(Z.GT.330..AND.Z.LT.440.) GOTO 850 IF(NDUM.EQ.3.AND.Z.GT.440.) CALL CKOUT(Z,ALF,YA,TL,N,NDUM) IF(Z.GT.440..AND.Z.LT.550) GOTO 850 IF(NDUM.EQ.4.AND.Z.GT.550.) C A L L CKOUT(Z,ALF,YA,TL,N,NDUM) IF(Z.GT.550..AND.Z.LT.650) GOTO 850 IF(NDUM.EQ.5.AND.Z.GT.655.) CALL CKOUT(Z,ALF,YA,TL,N,NDUM) IF(Z.GT.655.) GOTO 850 850 C C C C  CONTINUE IF(YA.LT.YAOUT) CALL CKOUT(Z,ALF,YA,TL,N,NDUM) 10. R E P E A T STEP 3 T O 9 UNTIL Y A FOR T H E O U T L E T GAS IS REACHED .  IF(YA.LT.YAOUT) GO T O 900 N=N+1 IF(N.GT.NSET) GO TO 900 WRITE(8,1111) Z,PA,ALF,TL,TG,E 1111 FORMAT(6F11.6) GOTO 300 C C C 11. CHECK T H E ASSUMPTION OF STEP 1. C IF NOT MATCHED, IT M A Y BE APPROPRIATE GUESS FOR C T H E NEXT ITERATION . HOWEVER, IF T H E SOLUTION IS FOUND C T O BE INSENSITIVE T O T H E ASSUMED VALUES OF T G AND YS  C C C C C C 900 905  (THROUGH T H E BACK CALCULATION OF O U T L E T LIQUID T E M P . FROM AN OVERALL ENTHALPY BALANCE) FURTHER ITERATION WILL NOT B E REQUIRED .  WRITE(6,905) F O R M A T ( / ' ***** T H E END CONDITION *****'/) WRITE(6,910) C T O T 910 F O R M A T ( / ' T O T A L CONCN. OF MEA \F10.5,' G-MOL/L') WRJTE(6,915) ALFIN FORMAT(' C02 LOADING (IN) \F10.5,' ') WRITE(6,920) LMIN 920 F O R M A T ^ INLET L. MOLAR VEL. \F10.5,' G-MOL/SEC.CM2') WRITE(6,925) TLIN 925 FORMATC INLET LIQUID T E M P . \F10.5,' C ) 915  WRITE(6,930) A L F O U T F O R M A T ( / ' C02 LOADING (OUT) \F10.5,' ') WRITE(6,945) T L O U T 945 FORMAT(' O U T L E T LIQUID T E M P . ',F10.5,' C ) 930  WRITE(6,950) GB F O R M A T ( / ' INLET AIR MOL. V E L . ',F10.5,'G-MOL/SEC.CM2') WRITE(6,955) YAIN 955 FORMATC INLET MOL F R A C . OF C02 '.F10.5) WRITE(6,960) YBIN 960 FORMATC INLET MOL FRAC. OF AIR \F10.5) WRITE(6,965) TGIN 965 FORMATC INLET GAS T E M P . *,F10.5,' C )  950  WRITE(6,970) Y A O U T F O R M A T ( / ' O U T L E T MOL FRAC. OF C02 \F10.5) WRITE(6,975) Y B O U T 975 FORMATC O U T L E T MOL F R A C . OF AIR \F10.5) WRITE(6,980) YSOUT 980 FORMATC O U T L E T MOL FRAC. OF H20 \F10.5) WRITE(6,985) T G O U T 985 FORMATC O U T L E T GAS T E M P . \F10.5,' C ) 970  990  WRITE(6,990) F O R M A T ( / ' ***>> CALCULATION RESULTS') WRITE(6,991) A L F  991 993  F O R M A T ( / ' C02 LOADING (IN) CAL. ',F10.5,7L') WRITE( 6,993) LM FORMAT(' INLET L. MOLAR VEL. \F10.5,' G-MOL/SEC.CM2') WRITE(6,994) T L  994  FORMATC INLET LIQUID T E M P . \F10.5,' C )  WRITE(6,995) Y A F O R M A T ( / ' OUTLET MOL FRAC. OF C02 ',F10.5) WRITE(6,996) YB 996 FORMAT(' OUTLET MOL FRAC. OF AIR \F10.5) WRITE(6,997) YS 997 FORMAT(' OUTLET MOL FRAC. OF H20 \F10.5) WRITE(6,998) T G 998 F O R M A T C OUTLET GAS T E M P . ',F10.5,' C ) 995  999  WRITE(6,999) Z F O R M A T C THE T O T A L HEIGHT \F10.5,' CM.'/)  C SCALING DO 1 1=1,N HT(I) = 2. + (HT(I)/(1.*100.)) PMIX = l.+PYS(I) +PYA(I) PMIXX = 1. + PYA(I) PYA(I) = 1. +((PYA(I)/(PMLXX))/0.03) PYS(I) = 1. +((PYS(I)/(PMLK))/0.03) PALF(I) = 1. + (PALF(I)/.l) T(I) = 1. + (T(I)*5./50.) PTG(I) = 1. + (PTG(I)*5./50.) 1 CONTINUE C PLOTTING CALL CALL CALL CALL CALL  AXIS(1.,.5,'P. CO2',-6,7.,0.,0.,0.03) AXIS(1.,1.,'P. H2O',-6,7.,0.,0.,0.03) AXIS(1.,1.5,'C02 LOADING',-11,7.,0.,0.,0.6) AXIS(1.,2.,'TEMP. (C)',-9,7.,0.,0,10.) AXIS(1.,2.,'HEIGTH (M)',10,7.,90.,0.,l.)  CALL PLOT(l.,2.,3) CALL PLOT(2.,2.,2) CALL PLOT(2.,9.,2) CALL PLOT(3.,9.,2) CALL PLOT(3.,2.,2) CALL PLOT(4.,2.,2) CALL PLOT(4.,9.,2) CALL PLOT(5.,9.,2) CALL PLOT(5.,2.,2) CALL PLOT(6.,2.,2) CALL PLOT(6.,9.,2) CALL PLOT(7.,9.,2) CALL PLOT(7.,2.,2) CALL PLOT(8.,2.,2) CALL PLOT(8.,9.,2) CALL PLOT(7.,9.,2) CALL PLOT(8.,3.,3)  321  CALL CALL CALL CALL CALL CALL CALL CALL CALL CALL CALL CALL CALL  PLOT(l.,3.,2) PLOT(l.,4.,2) PLOT(S.,4.,2)' PLOT(8.,5.,2) PLOT(l.,5.,2) PLOT(l.,6.,2) PLOT(8.,6.,2) PLOT(8.,7.,2) PLOT(l.,7.,2) PLOT(l.,8.,2) PLOT(8.,8.,2) PLOT(8.,9.,2) PLOT(l.,9.,2)  C A L L PLOT(l.,2.,3) D O 2 1=1,N C A L L SYMBOL(PYA(I),HT(I),.010,0,0.-2) CONTINUE  2  C A L L PLOT(l.,2.,3) D O 3 I=1,N C A L L SYMBOL(PYS(I),HT(I),.010,l,0.,-2) CONTINUE  3  C A L L PLOT(l.,2.,3)  4  D O 4I=1,N C A L L SYMBOL(PALF(I),HT(I),.010,2,0.,-2) CONTINUE C A L L PLOT(l.,2.,3)  5  D O 5 1=1 ,N C A L L SYMBOL(T(I),HT(I),.010,11,0.-2) CONTINUE C A L L PLOT(l.,2.,3)  6  D O 6 I=1,N C A L L SYMBOL(PTG(I),HT(I),0.01,5,0.,-2) CONTINUE C A L L SYMBOL(2.0,10.0,0.08,0,0.,-1) C A L L SYMBOL(2.2,10.0,0.08,'P-CO2 (ATM)',0.,11) C A L L SYMBOL(3.5,10.,0.08,1,0.,-1) . C A L L SYMBOL(3.7,10.,0.08,'P-H2O (ATM)',0.,11) C A L L SYMBOL(5.0,10.0,0.08,2,0.,-1) C A L L SYMBOL(5.2,10.0,0.08,'CO2 LOADING)',0.,11)  CALL SYMBOL(2.0,9.7,0.08,11,0.,-1) CALL SYMBOL(2.2,9.7,0.08,'LIQUID TEMP. (C)',0.,16) CALL SYMBOL(3.5,9.7,0.08,5,0.,-1) CALL SYMBOL(3.7,9.7,0.08,'GAS TEMP. (C)',0.,13) CALL PDATA(PEG,PEC,PET,PHT,NEX) DO 1001 I=1,NEX EG = 1.+ (PEG(I)/0.03) EC = 1. + (PEC(I)/.l) ET = l.+(PET(I)/10.) EH = 2.+(PHT(I)/100.) CALL SYMBOL(EG,EH,.12,0,0.-1) CALL SYMBOL(EC,EH,.12,2,0.-1) CALL SYMBOL(ET,EH,.12,11,0.,-1) 1001 CONTINUE CALL SYMBOL(4.,9.25,.25,'RUN# T22',0,8) CALL PLOTND STOP END Q  c C C  ************************************  SUBROUTINE CHACK(NIN,ALF,LM,TL,YA,YB,YS,TG,Z,NOUT) IMPLICIT REAL*8(A-M.O-Z)  WRITE(6,990) 990 FORMAT(/' :::: INTERMEDIAD CALCULATION RESULTS') WRITE(6,991) ALF 991 FORMAT(/' C02 LOADING ',F10.5,' ') WRITE(6,993) LM FORMATC LIQUID MOLAR VEL. ',F10.5,' G-MOL/SEC.CM2') WRITE(6,994) TL 994 FORMATC LIQUID TEMP. ',F10.5,' C ) 993  WRITE(6,995) YA FORMAT(/' MOL FRAC. OF C02 \F10.5) WRITE(6,996) YB 996 FORMATC MOL FRAC. OF AIR \F10.5) WRITE(6,997) YS 997 FORMAT(' FRAC. OF H20 ',F10.5) WRITE(6,998) TG 998 FORMATC GAS TEMP. \F10.5,' C ) 995  M  0  L  WRITE(6,999) Z  999  C  F O R M A T C T H E HEIGHT \F10.5,' CM.'/) NOUT = NOUT + 1 RETURN END  Q  c C C 990  **********************************************  SUBROUTINE CKOUT(Z,ALF,YA,TL,N,NDUM) IMPLICIT REAL*8(A-M,0-Z) WRITE(7,990) F O R M A T ( / ' :::: INTERMEDIAD CALCULATION RESULTS')  WRITE(7,999) Z F O R M A T ( / ' T H E HEIGHT ',F10.5,' CM.'/) PYA = 100 *YA/(1.+YA) WRITE(7,995) PYA 995 F O R M A T ( ' C02 CONC. (%) '.F10.5) WRITE(7,991) A L F 991 F O R M A T C C02 LOADING \F10.5,' ') 999  994 C  Q  WRITE(7,994) T L F O R M A T C LIQUID T E M P . \F10.5,' C ) NDUM=NDUM+1 RETURN END  ************************************************** SUBROUTINE PDATA(EG,EC,ET,EH,NEX) IMPLICIT REAL*8(A-H,0-Z) DIMENSION  EG(20),EC(20),ET(20),EH(20),G(20),C(20),T(20),H(20)  NEX=7 D A T A H/0.000,110.,220.,330.,440.,550.,655./ D A T A G/.1910,.1280,.0530,.0120,.0010,.000,-0/ C C = C02 LOADING D A T A C/.443,.292,.1250,:0330,0000,.0000,.0000/ D A T A T/47.0,45.0,29.0,21.0,19.0,19.,19./ DO 10 I=1,NEX EH(I)=H(I) EG(I)=G(I) EC(I)=C(I) 10 ET(I)=T(I) RETURN END  Q  ************************************************  SUBROUTINE SOL(TLK,CTOT,ALF,PEC02) IMPLICIT REAL*8(A-H,0-Z) C C A L PC02 A T EQUILIBRIUM IF(ALF.LE.0.3) PECO2=0.0 IF(ALF.LE.0.3) GOTO 100 DX1 = 2.9410 + (1.5940D+01)*(ALF) - (6.3439D-00)*(ALF**2) DX2=(2.6218D-01)*(1./ALF)+7.2388D-1*CTOT-(7.881D-02)*(CTOT**2) DX3 = -(8.9512D-02)*(TLK) + (1.8524D-04)*(TLK**2)  100  PEC02 = (DXl+DX2+DX3)/760. CONTINUE RETURN END  

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