METHOD OF PRODUCING NITROGEN ENRICHED AIR

摘要

A membrane separation process and apparatus involves contacting a gas feed mixture (19) with one side of a selectively gas permeable membrane (9) and allowing the components to pass through the membrane to form a permeate composition (17) in contact with the opposite side of the membrane and leave a retentate composition (15) on the feed side of the membrane. The process includes introducing a sweep flow of feed gas (24) into the permeate composition near the membrane at a rate effective to increase the enrichment of the retentate composition in the less preferentially permeable component of the feed mixture to a concentration much greater than is achieved without th e sweep flow. This process improves single stage membrane separation effectiveness so that the need for conventional multistage separations to achieve moderate to high purity retentate compositions can be obviated and i s particularly useful for providing enriched air in the concentration range of 80-90 vol. % nitrogen.