Rigorous modeling of a CO2-MEA stripping system

The complexity of the phenomena involved in CO2 chemical absorption and solvent regeneration systems results in the necessity to develop reliable models to describe the steady state and the dynamic behavior of the process. In the present work, the modeling of the regeneration section of a post-combustion CO2-MEA system have been examined. A rigorous rate-based approach, considered as mandatory for a reliable description of this type of process, was applied, where the two-film theory with chemical reaction was used to describe the gas/liquid interfacial material and energy transfer occurring in the packed column. The column was modeled as a convective-reactive system, with appropriate energy and material balances for each component. Particular emphasis was given to the definition of the correct number of segments for the discretization of the packing height. The effect of the axial diffusion/dispersion was analysed by means of the evaluation of the material and thermal Peclet number, and the results showed a plug-flow like behavior. The influence of the backmixing due to the countercurrent was also taken into account by varying the number of segments up to the achievement of an asymptotic behavior, confirming the correctness of the results obtained by the evaluation of the Peclet numbers. The model was validated with experimental data from a pilot-plant facility and the reproduction of the experimental values was deemed acceptable. The more detailed discretization allows to better describe the internal fluxes of the stripper column and has important implications in the design and in the extension to transient systems.