Comparisons of various absorbent effects on carbon dioxide capture in membrane gas absorption (MGA) process

Currently membrane gas absorption (MGA) is a novel approach for gas separation and purification. In this study, a wide-ranging 2D mathematical model for CO2 absorption from N2/CO2 mixture is proposed. Single solvents [H2O, ethylenediamine (EDA), diethanolamine (DEA), monoethanolamine (MEA), piperazine (PZ)] and blended solvent [DEA/PZ] were used as the absorbents. The non-wetting mode for the membrane contactor was considered in the models. The effects of gas concentration and velocity, and liquid concentration and velocity on CO2 removal were observed. The simulation results were verified with the experimental data showing a good agreement. The numerical results indicate that gas concentration and velocity have a negative effect on the capture process, while the liquid concentration and velocity enhance CO2 capture. Also, it is noted that PZ provides the best absorption performance than other single absorbents. The chemical solvents are much better than the physical solvent for CO2 absorption. In terms of blended absorbent based on amine solutions, its CO2 removal efficiency is around 20% higher than that of the single solutions. Thus, this model could provide the optimum operating conditions for acid gas absorption in the hollow fiber membrane module. At the same time, it is proved that the MGA approach exhibits a good potential in power-plant waste gas purification.