Hybrid prepurifier for cryogenic air separation plants

摘要

Feed air to a prepurifier adsorption system/cryogenic air separation system for dry, high purity nitrogen and/or oxygen production is dried in a membrance dryer preferably characterized by a countercurrent flow path. Drying is enhanced by the use of purge gas on the permeate side of the membrane dryer, with adsorption system or cryogenic air separation system product or waste gas, dried feed air or ambient air being used as purge gas. Two membrane materials are employed in the membrane dryer, in a single stage or in two stages, for enhanced removal of water and carbon dioxide from the feed air.