Pressure driven solid electrolyte membrane gas separation method

Claim 1

A process for removing oxygen from a feed stream to obtain an oxygen-depleted product stream and an oxygen byproduct stream, comprising: applying said feed stream to a first separator including a first feed zone and a first permeate zone separated by a first solid electrolyte mixed conduction membrane; driving a first portion of entrained oxygen in said feed stream from said first feed zone to said first permeate zone via said first membrane without applying a purge stream to said first permeate zone; obtaining an oxygen byproduct stream from said first permeate zone; directing a feed stream output from said first feed zone of said first separator to a second feed zone of at least a second separator, said second separator provided with a second permeate zone separated from said second feed zone by a second solid electrolyte ionic or mixed conduction membrane; driving a second portion of oxygen, which is entrained in said feed stream output from said first feed zone, from said second feed zone to said second permeate zone via said second membrane; obtaining an oxygen-depleted product stream after entrained oxygen has been removed from said second feed zone; and wherein said driving for said second separator is accomplished by establishing a Tower partial pressure of oxygen in the permeate zone for said second membrane by applying at least a purge stream to that permeate zone and includes diverting a portion of output from at least one of said first and second feed zones to purge the permeate zone of said second separator.