Abstract: A system and process for liquefying a gas, comprising introducing a feed stream into a liquefier comprising at least a warm expander and a cold expander; compressing the feed stream in the liquefier to a pressure greater than its critical pressure and cooling the compressed feed stream to a temperature below its critical temperature to form a high pressure dense-phase stream; removing the high pressure dense-phase stream from the liquefier, reducing the pressure of the high pressure dense-phase stream in an expansion device to form a resultant two-phase stream and then directly introducing the resultant two-phase stream into a storage tank; and combining a flash portion of the resultant two-phase stream with a boil-off vapor from a liquid in the storage tank to form a combined vapor stream, wherein the temperature of the high pressure dense-phase stream is lower than the temperature of a discharge stream of the cold expander.

Abstract: A method for the recovery of oxygen from air in which a high-temperature ion transport membrane system is integrated with combustion turbine system. Coproduction of oxygen and electric power is achieved in an alternative embodiment by integrating a combined cycle power generation system with an ion transport membrane system. The design performance of the gas turbine in the combined cycle system is maintained by controlled water injection into the membrane non-permeate stream, all or a portion of which optionally is introduced into the gas turbine combustor. Water can be introduced directly into the combustor air inlet. Alternatively, makeup air is added to the membrane feed to maintain the performance of the gas turbine. NOx formation is reduced by introducing the oxygen-depleted non-permeate from the membrane system to the gas turbine combustor.