Presentation on "Study of process intensification of CO2 capture through modelling and simulation" given by Dr Meihong Wang from University of Hull in the Process Engineering Technical Session at the UKCCSRC Biannual Meeting in Cambridge on 2-3 April 2014

1. STUDY OF PROCESS INTENSIFICATION
OF CO2 CAPTURE
THROUGH MODELLING AND SIMULATION
Atuman S. Joel, Meihong Wang, Colin Ramshaw and Eni Oko
School of Engineering, University of Hull

2. Background
Process Intensification
Motivations
Aim and Objectives
Rotating Packed Bed
Methodology
Model Validation
Process analysis
Future tasks
Conclusions
OUTLINE

3. BACKGROUND
Courtesy: IPCC

4. PROCESS INTENSIFICATION (PI)
PI is a strategy for making major
reductions in the volume of processing
plant without compromising its
production rate.
Rotating packed bed (RPB) is one of
PI technologies proposed originally by
Professor Ramshaw in 1979.
RPB takes advantage of centrifugal
force to generate high gravity and
consequently boost the mass transfer
performance.
Rotating Packed Bed used for REACTIVE
STRIPPING –40 times smaller plant (Dow
Chemical, HOCl process)

5. BERR (2006) reported that a 500 MWe
supercritical coal fired power plant operating at
46% efficiency (LHV basis) would release over
8,000 tonnes of CO2 per day.
Raynal and Royon-Lebeaud (2007) reported that
for 400 MWe coal-fired power plant it produces
approximately 1.1 x 106 Nm3/h of flue gas.
Lawal et al. (2012) reported two absorbers will
be required of 17m in packing height and 9m in
diameter to separate CO2 from flue gas of
500MWe subcritical coal fired power plant.
MOTIVATIONS

6. The aim of the study is to compare conventional and
intensified post-combustion CO2 capture (PCC)
plant for their performance in CO2 capture. The
following objectives are intended to accomplish the
aim.
 Modelling, simulation and validation of standalone
intensified absorber using RPB.
 Modelling, simulation and validation of standalone
intensified stripper using RPB.
 Modelling and simulation of intensified PCC plant.
 Scale-up of intensified PCC plant.
AIM AND OBJECTIVES

7. ROTATING PACKED BED
Schematic diagram of a rotating packed bed setup and corresponding segmentation
(Llerena-Chavez and Larachi, 2009 )

8. METHODOLOGY

9. CORRELATIONS SETS
Correlation sets used for the modelling and simulations
Correlations Set 1 Set 2
Liquid-phase mass transfer coefficient Tung and Mah (1985) Chen et al., (2006)
Gas-phase mass transfer coefficient Onda et al., (1968) Chen, (2011)
Interfacial area Onda et al., (1968) Luo et al. (2012)
Liquid hold-up Burns et al., (2000) Burns et al., (2000)
Dry pressure drop Llerena-Chavez and
Larachi (2009)
Llerena-Chavez and
Larachi (2009)

10. Variable Runs
Run 1 Run 2 Run 3 Run 4
Rotor speed (RPM) 600 1000 600 1000
Lean MEA temperature (oC) 39.6 40.1 41 40.2
Lean MEA pressure (atm.) 1 1 1 1
Flue gas flow rate (kmol/hr) 2.87 2.87 2.87 2.87
CO2 composition in Flue gas (vol
%)
4.71 4.48 4.40 4.29
Lean-MEA flow rate (kg/s) 0.66 0.66 0.66 0.66
Lean-MEA composition (wt %)
H2O
CO2
MEA
40.91
3.09
56.00
40.91
3.09
56.00
22.32
2.68
75.00
23.41
2.59
74.00
MODEL VALIDATION
Input process conditions for Run 1 to Run 4 (Jassim et al., 2007)

11. Variable Run 1 Run 2
Expt. Set 1 Error 1 Set 2 Error 2 Expt. Set 1 Error 1 Set 2 Error 2
CO2 loading of Lean MEA,
(mol CO2/mol MEA)
0.0772 0.0772 0.0772 0.0772 0.0772 0.0772
CO2 loading of Rich MEA,
(mol CO2/mol MEA)
0.0828 0.0827 0.1208 0.0829 0.1208 0.0828 0.0825 0.3623 0.0827 0.1208
Average Lean MEA/Rich
MEA, (mol CO2/mol MEA)
0.0800 0.0800 0.0000 0.0800 0.0000 0.0800 0.0799 0.1250 0.0801 0.1250
CO2 capture level (%) 94.9 92.9 2.1075 96.72 1.9178 95.4 93.26 2.2432 96.95 1.6247
MODEL VALIDATION
Simulation results with 2 different sets of correlations compared to the
experimental data for Run 1 and Run 2

12. Variable Run 3 Run 4
Expt. Set 1 Error 1 Set 2 Error 2 Expt. Set 1 Error 1 Set 2 Error 2
CO2 loading of Lean–MEA
(mol CO2/mol MEA)
0.0492 0.0492 0.0492 0.0483 0.0483 0.0483
CO2 loading of Rich-MEA
(mol CO2/mol MEA)
0.0531 0.0530 0.1883 0.0531 0.0000 0.0510 0.0521 2.1569 0.0524 2.7451
Average Lean-MEA/Rich-
MEA (mol CO2/mol MEA)
0.0512 0.0511 0.1953 0.0512 0.0000 0.0497 0.0502 1.0060 0.0503 1.2072
CO2 capture level (%) 98.20 93.28 5.0102 97.36 0.8554 97.50 93.57 4.0308 98.66 1.1897
MODEL VALIDATION
Simulation results with 2 different sets of correlations compared to the
experimental data for Run 3 and Run 4

13. CONCLUSION FROM VALIDATIONS
 Set 2 correlations gives a better error prediction
compared to Set 1.
 The difference in error prediction at 56 wt% MEA
concentration between Set 1 and Set 2 is not large
 There is wide error prediction at 74 wt% MEA
concentration between Set 1 and Set 2
 Set 2 correlations account for the effect of viscosity
and packing geometry while Set 1 correlations do
not.

14. PROCESS ANALYSIS
Variable Case 1 Case 2 Case 3 Case 4
Rotor speed (RPM) 400 400 400 400
Lean temperature (oC) 20.9 39.5 20.9 39.5
Lean pressure (atm.) 1 1 1 1
Flue gas flow rate (kmol/hr) 2.87 2.87 2.87 2.87
CO2 composition in flue gas (vol %) 4.35 4.35 4.35 4.35
Lean-MEA flow rate (kg/s) 0.66 0.66 0.66 0.66
Lean-MEA composition (wt %)
H2O
CO2
MEA
41.03
3.97
55.00
41.03
3.97
55.00
22.32
2.68
75.00
22.32
2.68
75.00
 For all cases the input parameters are kept constant with rotor speed
varied from 400 rpm to 1200 rpm
Process input conditions
a. Effect of Rotor Speed on CO2 Capture Level

15. Effect of rotor speed on CO2
capture level at 75wt% MEA
Effect of rotor speed on CO2
capture level at 55wt% MEA
80
82
84
86
88
90
92
94
96
98
200 700 1200 1700
CO2absorptionlevel(%)
Rotor speed (RPM)
Case 1
Case 2
82
84
86
88
90
92
94
96
98
100
200 700 1200 1700
CO2absorptionlevel(%)
Rotor speed (RPM)
Case 3
Case 4
RESULTS & DISCUSSIONS

16. RESULTS & DISCUSSIONS
CO2 capture level increases with increase in rotor
speed.
75 wt% MEA concentration capture level is higher
than at 55 wt% MEA concentration.
Burns et al. (2000) stated that at higher centrifugal
acceleration, combined droplet and film flow are
prevalent in an RPB absorber leading to enhanced
mass transfer flux.
At higher rotor speed, the problem of liquid mal-
distribution is overcome leading to higher wetted area
which subsequently contributes to improving mass
transfer.

17. PROCESS ANALYSIS CONT.
b. Effect of MEA concentration on CO2 capture level
Process input condition for this case is same as Case 1 and Case 3 above
with rotor speed changed and kept constant at 1000 rpm.
86
88
90
92
94
96
98
100
50 60 70 80
CO2Capturelevel(%)
MEA concentration (wt%)
39.5℃ Lean-MEA tem
20.9℃ lean-MEA temp.

18. RESULTS & DISCUSSIONS
Increasing MEA concentration will means increase in
hydroxide ions per unit volume which will results in
capture of more CO2 at constant liquid and gas flow
rate.
Reaction rate will increase with increase in
concentration.
Increase in Lean-MEA temperature results in increase
in CO2 capture level since reaction rate increase with
temperature.

19. PROCESS ANALYSIS CONT.
82
84
86
88
90
92
94
96
98
100
102
0 20 40 60 80 100
CO2Capturelevel(wt%)
Lean-MEA temperature (oC)
55 wt% MEA
75 wt% MEA
c. Effect of Lean-MEA Temperature on CO2 Capture Level
Process conditions same Case 1 and Case 3. The lean MEA temperature is
varied from 25 oC to 80 oC at 55 wt% and 75 wt% lean MEA concentrations.

20. RESULTS & DISCUSSIONS
The improvement of RPB performance as temperature
increases can be associated to:
 Decrease in viscosity of the MEA as temperature
increases as stated by Lewis and Whitman (1924) that
kinematic viscosity of film fluid is the controlling
factor in determining its film thickness.
 This phenomena leads to improvement in diffusion rate
of CO2 into lean MEA solvent.
 Increasing lean solvent temperature leads to faster
reaction rate.

21. PROCESS ANALYSIS CONT.
49.8
50
50.2
50.4
50.6
50.8
51
51.2
51.4
51.6
51.8
52
0 0.05 0.1 0.15 0.2 0.25
Temperature(oC)
Radial distance from outer radius to inner radius (m)
55 wt%
75 wt%
Process conditions same as Case 1 and Case 3. The flue gas temperature was
maintained at 47 oC. The temperature profile is studied at two lean MEA
temperatures of 25 oC and 50 oC.
Liquid temperature profile in RPB absorber at 25 oC lean MEA
temperature
Liquid temperature profile in RPB absorber 50 oC lean MEA
temperature
d. Temperature profile in RPB absorber
24.5
25
25.5
26
26.5
27
27.5
0 0.05 0.1 0.15 0.2 0.25
Temperature(oC)
Radial distance from outer radius to inner radius (m)
55 wt%
75 wt%

22. RESULTS & DISCUSSIONS
Temperature bulge problem is not pronounced in RPB as
can be seen in the figures shown. The reason for this
could be
 Because of the high gravity, most of the flow in RPB is
droplet and thin film flow. This makes it difficult for
liquid build-up in the packing which may result in
energy build-up.
 High degree of mixing and little residence time of the
solvent in column makes it difficult to have energy
build-up.

23. PROCESS ANALYSIS CONT.
0
10
20
30
40
50
60
70
80
90
100
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9
CO2capturelevel(%)
Flue gas flow rate (kg/s)
Run 2
Run 4
e. Effect of Flue Gas Flow Rate on CO2 Capture Level

24. In both Runs, CO2 capture level decrease as
the flue gas flow rate increases.
This is associated with decrease in contact
time between the flue gas and liquid MEA
solvent
The trend is independent of MEA concentration
of the solvent the trend is the same
DISCUSSIONS OF RESULT

25. INTENSIFIED ABSORBER VS
CONVENTIONAL ABSORBER
Description Conventional absorber RPB absorber
Flue gas Lean-MEA Flue gas Lean-MEA
Temperature (K) 323.15 313.25 323.15 313.25
Pressure (105Pa) 1.186 1.013 1.186 1.013
Total flow (kg/s) 0.0228 0.0454 0.0228 0.0440
L/G (kg/kg) 1.99 1.93
Mass-Fraction
H2O
CO2
N2
MEA
0.0030
0.0666
0.9304
0
0.6334
0.0618
0
0.3048
0.0030
0.0666
0.9304
0
0.23426
0.02574
0
0.74000

26. Description Conventional
absorber
RPB absorber
Height of packing (m) 3.85 0.2885 (ro)
0.078 (ri)
diameter (m) 0.395 0.0377 axial depth
Packing Volume (m3) 0.4718 0.0091
Packing volume reduction 52 times
Volume of unit (m3) 0.4718 b 0.04095bc
Volume reduction factor 12 times
Specific area (m2/m3) 145 2132
Void fraction 0.79 0.76
Lean-MEA loading (mol CO2/mol MEA) 0.2814 0.0483
Rich-MEA loading(mol CO2/mol MEA) 0.4189 0.1069
RESULTS & DISCUSSIONS

27. Keeping the CO2 capture level at 90% for both
simulation runs.
Using the assumption Agarwal et al. (2010) that
the casing volume of RPB is taken as 4.5 times
the RPB volume.
Volume of the conventional absorber and RPB
absorber without the sump, it was found that
conventional absorber is 12 times the volume of
RPB.
RESULTS & DISCUSSIONS

28. New simulation procedure has been
successfully developed.
Model has been validated with experimental
results.
The effect of Lean-MEA temperature, Rotor
speed, MEA concentration and flue gas flow
rate on CO2 capture level were studied.
Temperature profile of the RPB were studied.
Comparison between conventional and
intensified absorber indicates a significant
volume reduction.
CONCLUSIONS

29. If you have interest in the work, please
read the following two recent publications:
Joel, A. S., Wang, M. and Ramshaw, C. (2014),
Process analysis of intensified absorber for post-
combustion CO2 capture through modelling and
simulation, Int. Journal of Greenhouse Gas Control,
Vol. 21, p91-100.
Joel. A, S., Wang, M., Ramshaw, C. (2014), Modelling
and simulation of intensified absorber for post-
combustion CO2 capture using different mass transfer
correlations, Applied Thermal Engineering, doi:
10.1016/j.applthermaleng.2014.02.064.
CONCLUSIONS

30. Modelling, simulation and validation of intensified
stripper using Aspen Plus and visual FORTRAN
Dynamic modelling, simulation and validation of
intensified absorber using gPROMS
Dynamic modelling, simulation and of intensified
stripper using gPROMS
Modelling and simulation intensified post-
combustion CO2 capture (PCC) plant
Scale-up of intensified post-combustion CO2
capture (PCC) plant
FUTURE WORK

31.  Agarwal, L., Pavani , V., Rao, D . P., Kai stha, N., 2010. Process i ntensi fi cati on i n Hi Gee
absorpti on and di sti llati on: D esi gn procedure and appli cati on. Ind. Eng. C hem . R es. 49(20),
10046-10058.
 BERR, (2006) Advanced power plant usi ng hi gh effi ci ency boi ler/turbi ne. Report BPB010.
BERR, D epartment for Busi ness Enterpri se and Regulatory Reform; Avai lable at:
www.berr.gov.uk/ fi les/ fi le30703.pdf. (accessed 6/04/2012)
 Burns, J. R., Jami l, J. N., Ramshaw, C ., 2000. Process i ntensi fi cati on: operati ng
characteri sti cs of rotati ng packed beds — determi nati on of li qui d hold-up for a hi gh-voi dage
structured packi ng. C hem i cal Engi neeri ng Sci ence 55(13), 2401-2415.
 Intergovernme ntal Panel on C li mate C hange, 2007. C ontri buti on of Worki ng Group III to the
Fourth Assessment Report of the Intergovernme nta l Panel on C li mate C hange. C ambri dge
Uni versi ty Press, C ambri dge, Uni ted Ki ngdom/New York, Uni ted States.
 Jassi m, M. S., Rochelle, G., Ei mer, D ., Ramshaw, C ., 2007. C arbon di oxi de absorpti on and
desorpti on i n aqueous monoethanolami ne soluti ons i n a rotati ng packed bed. Industri al &
Engi neeri ng C hem i stry R esearch 46(9), 2823-2833.
 Lawal, A., Wang, M., Stephenson, P., Obi , O., 2012. D emonstrati ng full-scale post-
combusti on C O2 capture for coal-fi red power plants through dynami c modelli ng and
si mulati on. Fuel 101, 115-128.
 Llerena-C havez, H., Larachi F., 2009. Analysi s of flow i n rotati ng packed beds vi a C FD
si mulati ons—D ry pressure drop and gas flow maldi stri buti on. C hem i cal Engi neeri ng Sci ence
64, 2113-2126.
 Lewi s, W. K., Whi tman, W. G., 1924. Pri nci ples of gas absorpti on. Industri al and
Engi neeri ng C hem i stry 16(12), 1215-1220.
REFERENCES

32. THANK
YOU