Air fractionation process - for nitrogen and oxygen production

摘要

Air is fractionated to produce liquid nitrogen and oxygen by initial compression and removal of impurities e.g. water, carbon dioxide before cooling to -177 degrees C with nitrogen effluent from the fractionation column. Supplementary cooling is achieved by a series of compression and refrigeration stages, utilising liquefied low pressure natural gas or methane, to further reduce the input gas temp. to -195 degrees C. Fractionation is effected with high utilisation of specific energy and the methane refrigeration is applied to the nitrogen only reducing the risk of explosion encountered with conventional air cooled input gases.