Improved process for the production of nitrogen at a relatively high yield and Purity

摘要

The present invention provides a process for the production of nitrogen at relatively high yield and purity by cryogenic rectifiction of feed air characterized by… (1) introducing the major portion of the feed air into a rectification column which is operating at a pressure in the range of from 241 to 1000 kPa (from 35 to 145 psia), and wherein feed air is separated into nitrogen-rich vapour and oxygen-enriched liquid;… (2) condensing a minor portion of the feed air, at a pressure greater than that at which the column is operating. by indirect heat exchange with oxygen-enriched liquid;… (3) introducing the resulting condensed minor portion of the feed air into the column at a point at least one tray above the point where the major portion of the feed air is introduced into the column;… (4) condensing a first portion of the nitrogen-rich vapour by indirect heat exchange with vapourizing oxygen-enriched liquid;… (5) passing at least some of the resulting condensed nitrogen-rich portion to the column at a point at least one tray above the point where the minor portion of the feed air is introduced into the column; and… (6) recovering substantially the entire remaining second portion of the nitrogen-rich vapour as product nitrogen.