Membrane-based natural gas separation has become one of the promising technologies due to its compactness, energy efficiency, environment friendliness and economic advantages. In this work, a three stage membrane process for the separation of CO2/CH4 is proposed based on a novel fixed site carrier membrane which has the potential to meet the CO2/CH4 separation and durability requirement. A simulation analysis, which utilizes the Aspen Hysys capabilities to calculate and couple energy balances in the process model, has been conducted to investigate the effect of process parameters on the gas processing cost. Two different natural gas mixtures containing 9.5% and 2.9% CO2 have been simulated for various process conditions. This fixed site carrier membrane performs well when wetted with water. Therefore, natural gas feed streams are saturated with water. It is evident from the analysis that it is possible to maintain 2% CO2 in retentate and methane loss in permeate below 2% by optimizing the process conditions. The analysis shows that fixed site carrier membrane offers a viable solution for natural gas sweetening.

Arshad Hussain, Habib Nasir and Muhammad Ahsan