CFD simulation of natural gas sweetening in a gas–liquid hollow-fiber membrane contactor

Chemical absorption of CO2 and H2S from natural gas was studied theoretically and experimentally using a hollow-fiber membrane contactor (HFMC) in this work. A 2D mathematical model was proposed to study simultaneous transport of CO2 and H2S through a HFMC using methyldiethanolamine (MDEA) as chemical absorbent. The model considers axial and radial diffusion in the HFMC. It also considers convection in tube and shell sides with chemical reaction. CFD techniques were applied to solve the model equations involving continuity and momentum equations. Modeling predictions were validated with the experimental data and it was found that there is a good agreement between them for different values of gas and liquid velocities. The simulation results showed that the removal of H2S with aqueous solution of MDEA was very high and indicated almost total removal of H2S. Experimental and simulation results indicated that the membrane module was very efficient in the removal of trace H2S at high gas/liquid flow ratio. The removal of H2S was almost complete with recovery of higher than 96%. The proposed model is able to predict the performance of CO2 and H2S absorption in HFMCs.