Patent ID: 6116052
Filing Date: 2000-09-12
Classification: F25J

Abstract:
A cryogenic air separation process comprising the steps of:(a) feeding cooled air, substantially free of impurities, to a high pressure column to yield a first nitrogen-enriched gas at the top of the high pressure column and a first oxygen-enriched liquid at the bottom of the high pressure column;(b) at least partially condensing the first nitrogen-enriched gas to yield a first nitrogen-enriched liquid stream, returning at least a portion of the first nitrogen-enriched liquid stream to the high pressure column as reflux and recovering a portion of the nitrogen-enriched gas as nitrogen product;(c) feeding at least a portion of the first nitrogen-enriched liquid stream to an intermediate pressure column wherein a second nitrogen-enriched liquid is produced at the top of the intermediate pressure column and a second oxygen-enriched liquid at the bottom of the intermediate pressure column and feeding at least a portion of the second nitrogen-enriched liquid to a low pressure column;(d) producing a third oxygen-enriched liquid in the low pressure column; and(e) vaporizing at least a portion of the third oxygen-enriched liquid in an overhead condenser of the intermediate pressure column or of the low pressure column.