Rate-Based Modeling for Packed Absorption Column of the MEA-CO2-Water System at High-Pressure and High-CO2 Loading Conditions

Pandya proposed the first steady-state rate-based model for the chemical absorption process in a packed column using the aqueous CO2-MEA system. Later several modeling studies are also reported based on Pandya's approach but limited to low pressure (approximate to 1 bar) and low CO2 loadings (<0.5 mol/mol). Recently, the interest in processing CO2-rich natural gas at high-pressure conditions has been increased. Therefore, in this study, the Pandya model is modified to simulate the packed absorption column using an aqueous CO2-MEA system for the high-pressure and high-CO2 loading range. The sequential chemical reactions, along with the respective mass transfer resistances that occur at low (<0.5 mol/mol) and high (>0.5 mol/mol) CO2 loadings, are added. This is achieved by theoretically segmenting the packed column into two sections. This strategy simplifies the computation of subsequent fast and slow reaction regimes that occur over a high-CO2 loading range. The gas-liquid nonideal behavior is described using the Peng Robinson (EOS) and Kent Eisenberg models. The developed model is effectively validated using the experimental data at low-(approximate to 1.03 bar) and high-(50 bar) pressure conditions over a wide CO2 loading range (approximate to 0-1.0 mol/mol). In a parity plot between measured and simulated CO2 concentration, R-2 is found to be 0.99 and 0.97, respectively, for the low-(approximate to 1.03 bar) and high- (50 bar) pressure systems. This indicates that the proposed model can accurately predict the critical design parameters at the high-pressure and high-CO2 loading conditions, with minimum computational intricacy.