Abstract: A method of purifying a gas stream by removing oxygen from the gas stream in which the gas stream is introduced into a series of electrically driven oxygen separation zones that separate the oxygen from the gas stream. Each of the electrically driven oxygen separation zones has an electrolyte that conducts oxygen ions upon the application of the voltage to electrodes sandwiching the electrolyte. The voltage applied to each of the electrodes of the separation zones is selected such that an ionic current induced in the electrolyte within a particular zone that is no greater than a limiting current. When voltage is applied in such manner, the electrical power that is consumed is reduced over the power that would otherwise be consumed had a constant voltage been applied to all zones. The gas stream can be a crude argon stream obtained from a crude argon column or a crude nitrogen stream obtained from a pressure swing adsorption unit or a polymeric membrane unit.

Abstract: A method of separating oxygen from an oxygen containing stream in which compressed and heated oxygen is introduced into cathode side of an oxygen transport membrane reactor. Oxygen is permeated from the cathode side to the anode side. Motive fluid that is introduced into an ejector draws an oxygen permeate containing stream from the anode side at a subatmospheric pressure to form an oxygen containing product stream. The motive fluid, which can be steam raised by combustion used in heating the reactor, can be separated from the oxygen containing product stream to form an oxygen product stream. The use of an ejector lowers the partial pressure of the oxygen at the anode side of the membrane reactor and therefore the degree to which the oxygen containing stream need be compressed.