Theoretical Study on CO₂Absorption from Biogas by Membrane Contactors: Effect of Operating Parameters

Biogas upgrading and utilization is a novel technology to obtain resource-efficient vehicle fuel. In this study, a mass transfer model for CO 2 absorption from biogas into potassium argininate (PA) solutions was developed. The computational fluid dynamics (CFD) methods were employed to solve the differential equations in three domains of the membrane contactor. The simulations were focused on the characteristics of both gas and absorbent phases to demonstrate the concentration distributions in axial and radial directions in the module. The simulated results were in excellent agreement with experimental data when considering the effect of initial CO 2 concentration and gas velocity. Furthermore, the effect of operating pressure, flow pattern, flow condition, and modules in series on the membrane performance was investigated. The results showed the purity of CH 4 reached 95% with the operating pressure of 0.9 MPa. It was found that a fluid in the turbulent condition or counter-current configuration had a significant effect on improving the contactor performance. The simulation results also indicated that the use of two modules could increase CO 2 removal and obtain high CH 4 purity. Finally, the results confirmed that the developed 2D model was able to predict the behavior of CO 2 separation in the membrane contactors.