Multi-stage gas separation process for separation of carbon dioxide from methane: Modeling, simulation, and economic analysis

Abstract

The emphasis of this study is the use and comparison of the rubbery and glassy membranes in the multi-stage gas separation process for separation of the CO2/CH4 mixtures. For analysis of the gas separation processes, reliable modeling and simulation of the process are essential. Thermodynamic models of lattice fluid (LF) and non-equilibrium lattice fluid (NELF) were used to model the gas sorption in the rubbery and glass membranes, respectively, and a transfer model was employed to model the gas diffusion. The developed model was integrated with the Aspen Custom Modeler (ACM) of Aspen Plus software to simulate various proposed gas separation processes. The performance of single-stage and multi-stage processes was evaluated in terms of the CH4 recovery, product purity, total capital investment, and total annual cost. It was found that the membranes with higher permeability had more suitable economic parameters than the membranes with high CO2/CH4 selectivity. The results showed that the CH4 recovery of 99% and product purity of 98% could not be achieved by the single-stage process. However, the desired separation criteria can be met via the multi-stage membrane processes with two or three membranes. The best configuration was chosen from different configurations by examining the economic parameters.