A practical approach to enhancing energy efficiency in dual-stage membrane processes for various industrial gas separations: Membrane combination optimization

Abstract

Membrane-based separation technology offers notable advantages in terms of its compact size and energy efficiency. However, single-stage membrane processes encounter limitations in achieving high levels of purity for target gases, particularly when dealing with low feed concentrations, due to the constrained separation performance of polymeric membranes. Herein, we report on the optimization of dual-stage membrane processes for diverse gas separation applications, including CO2/N2, CO2/CH4, H2/N2, and H2/CH4 separation. The optimization process involves the utilization of various membrane combinations, which are carefully selected using a user-friendly apparent selectivity model. In particular, our evaluation includes an assessment of the separation performance of the proposed membrane combinations for different molar fractions in the feed while maintaining a fixed target purity. Additionally, we determine their practical feasibility by estimating other process parameters such as the required membrane area, energy demand, and material cost. Through process analysis, it is observed that a combination of more selective membranes in the first stage and more permeable membranes in the second stage can yield economic benefits for various gas separation applications. The present study provides a practical approach to enhancing the process efficiency of a dual-stage membrane process for various gas separation applications.