Presentation given by Sai Gu of Cranfield University on "Computational Modelling and Optimization of Carbon Capture Reactors" at the UKCCSRC Gas CCS Meeting, University of Sussex, 25 June 2014

1. Computational Modelling
and Optimization of Carbon
Capture Reactors
Prof. Sai Gu, School of Engineering,
Cranfield University
s.gu@cranfield.ac.uk

2. Post Combustion CO2
Capture with Solutions
Source: UK CCS Research Centre
• Amine solution reacts
reversibly with CO2
• CO2 is recovered in the
stripper using steam
• Large gas-liquid interfacial
area required to facilitate
amine-CO2 reactions.

3. Multiscale Problem
Micro-scale: the liquid flow along
the packing walls requires
microscopic analysis to determine
characteristics, e.g., liquid hold
up.
Meso-scale : the flow dynamics
between the packing sheets.
Macro-scale: the flow influences
due to reactor walls, inlets,
distributors etc.,

4. Develop VOF based CFD model for gas-liquid flows through packing wall of single
element
• Hydrodynamics
• Physical mass transfer
• Reactive mass transfer
Micro Scale Models
CFD Modelling methods
(a) Computational domain (b) Mesh details

5. Effect of wall surface texture
Micro-Scale
Hydrodynamics
Effect of contact angle
(a) trickling flow (b) rivulet flow (c) full film flow
(a) 100° (b) 70°
Wetted area validation

6. Micro-Scale Mass Transfer
MEA solution effects on the oxygen
absorption rate for various liquid loads
Averaged absorbed oxygen mass fraction
vs. time for different liquid loads
Averaged absorbed oxygen mass fraction
vs. time for gas phase velocity
Sherwood Number vs. Reynolds Number

7. Micro-Scale Reactive Mass
Transfer
Concentration profiles with and without
chemical reaction
Enhancement factor vs. MEA concentration
Liquid side mass transfer Coefficient vs. MEA concentration

8. (a) t=0.1 s (b) t=0.4 s (c) t= 1.0sec (d) t=1.5s
Meso Scale Models with
Ammonia
NH4HCO3 mole fraction vs. time

9. Meso Scale Results
Effect of liquid flow rate Effect of gas flow rate
Effect of inlet CO2 concentration Effect of NH3 concentration

10. Experimental results (Fourati et al., 2012) No dispersion model
Large Scale Models

11. Effect of Dispersion
Models
Liquid dispersion model (Lappalainen et al., 2009)Liquid dispersion model (Mewes et al., 1999)

12. Comparison with
Experiments
Comparison of radial liquid saturation profiles from CFD and experimental at various axial positions of
(a) z=0.32 m (b) z=0.48 cm (c) z=0.74 m
(a)
(c)
(b)

13. Conclusions and Future
works
• For micro-scale, a 3-dimensional, VOF model was developed to study the
Hydrodynamics, physical mass transfer and reactive mass transfer between
gas and liquid phases occurring in the metallic plates of structured packed
columns.
• For meso-scale, a 3-dimensional, multiphase model was developed to study
reactive mass transfer between gas and liquid phases occurring in
Representative Elements Units (REUs) of structured packed columns.
• For large-scale, a 3-dimensional, multiphase model was developed to study
liquid dispersion in structured packed columns.
• In future, the coupling of each models results will be developed.

14. Acknowledgement
• EPSRC project (EP/J020184/1 ): Computational Modelling and
Optimisation of Carbon Capture Reactors