Patent ID: 6470707
Filing Date: 2002-10-29
Classification: F25J

Abstract:
A Process for obtaining gaseous nitrogen by low-temperature separation from air in a distillation column system, having a single column (4), comprising the following stages:compressed air is cooled in a main heat exchanger, and fed to single column; a nitrogen-rich fraction is drawn off from the distillation column system and is compressed, at least in part, in a circulation compressor; a first part of compound nitrogen-rich fraction is fed downstream from the circulation compressor to a liquefaction chamber of a condenser-evaporator and is condensed therein under a pressure higher than the operating pressure of the single column, thereby forming a nitrogen-rich liquid; a liquid, oxygen-enriched fraction is withdrawn from the distillation column system and is at least partially evaporated in an evaporation chamber of the condenser-evaporator; a first oxygen-enriched gas is withdrawn from the evaporation chamber and introduced into the single column, as ascending vapor; and a second part of the compressed nitrogen-rich fraction is withdrawn at least at times as gaseous nitrogen product, and wherein a second oxygen-enriched gas is withdrawn from the evaporation chamber of the condenser-evaporator, is work expanded, and is heated in the main heat exchanger.