Membrane/cryogenic hybrid scheme for argon production from air

Abstract

A novel membrane/cryogenic hybrid scheme is presented wherein crude argon from a cryogenic air separation unit is fed to an oxygen selective membrane unit to remove a substantial portion of the oxygen. The oxygen enriched permeate from the membrane unit is returned to the crude argon distillation column of the cryogenic air separation process. The non-permeate stream is enriched in argon and can be further purified in a catalytic unit to produce an oxygen-free argon stream. The proposed process makes use of the synergy between the two separation units whereby, the cryogenic unit offers high recovery and the membrane provides purification leading to improved argon recoveries at higher argon concentrations. Calculations show that this process, in conjunction with an oxygen removal catalytic process, provides an economical alternative for the production of pure argon as compared to the conventional process using just a cryogenic unit and a catalytic unit to remove oxygen.