Comparison of rate-based and equilibrium-stage models of a packed column for post-combustion CO2 capture using 2-amino-2-methyl-1-propanol (AMP) solution

Abstract

In this study, two mathematical models including rate-based and equilibrium-stage were applied and compared for CO2 absorption by 2-amino-2-methyl-1-propanol (AMP) solution in a packed column. In the rate-based model, process of simultaneous mass and energy transfer across the interface was modeled by means of rate equation and mass transfer coefficients. The rate-based model was based on the two-film theory. In contrast, the equilibrium-stage model was based on the theory of theoretical number stages combined with the concept of Murphree efficiency. In this model, different values of Murphree efficiencies were used along the absorption column. The two modeling approaches were validated by comparison of obtained results with published experimental data. The simulation of the absorber column shows the rate-based model gives a better prediction of the temperature and concentration profiles compared to the equilibrium-stage model. As a result, for a detailed process design the rate-based model should be applied. Also, comparison of the absorption performance between the CO2-MEA and CO2-AMP system in a bench-scale absorber packed with high efficiency packing was performed. Finally, The effect of important process parameters such as CO2 partial pressure, CO2 loading of amine solution, flow rate of amine solution, concentration of amine solution and solution temperature on the CO2 removal efficiency were analyzed. The results of this analysis showed that CO2 removal efficiency increases with the increase of solution flow rate, solution concentration and solution temperature (in the CO2 loading of more than 0.15) and decreases with the increase of the CO2 loading of AMP solution (in the CO2 loading of more than 0.15) and CO2 partial pressure.