Unsteady state cyclic pressure-vacuum swing permeation for low pressure niche gas separation applications

A relatively higher transmembrane driving force compared to conventional steady state membrane process can be achieved in unsteady state cyclic pressure-vacuum swing permeation process, which accomplishes feed pressurization and permeate evacuation using a single pump. Moreover, a higher feed to permeate pressure ratio can be achieved and the enhanced transmembrane driving force can also be sustained over a longer period of time, which enhances gas separations. Improved separation efficiency in terms of product purity and throughput compared to the conventional steady state membrane gas separation process can be obtained for low pressure niche applications by means of pressure-vacuum swing permeation. CO2 separation for greenhouse gas emission control, oxygen-enriched air production and methane enrichment from biogas are shown as exemplary model applications to demonstrate the feasibility and effectiveness of this novel process.