Method of producing nitrogen enriched air

摘要

A membrane separation process and apparatus for carrying out the process involves contacting a gas feed mixture with one side of a selectively gas permeable membrane and allowing the components to pass through the membrane to form a permeate composition in contact with the opposite side of the membrane and leave a retentate composition on the feed side of the membrane. The process includes introducing a sweep flow of feed gas 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 the sweep flow. This process is especially well suited to improve single stage membrane separation effectiveness so that the need for conventional multistage separations to achieve moderate to high purity retentate compositions can be obviated. The novel process is particularly useful for providing enriched air in the concentration range of 80-90 vol. % nitrogen.