Patent ID: 6082137
Filing Date: 2000-07-04
Classification: F25J

Abstract:
A method of separating air:introducing a first stream of purified, compressed, gaseous air at a temperature suitable for its separation by rectification into a higher pressure rectification column of a double rectification column;the double rectification column also having a lower pressure rectification column in heat exchange relationship with the higher pressure rectification column through a condenser reboiler, of which said condenser-reboiler provides liquid nitrogen reflux for separation and an upward flow of vapor in the lower pressure column;introducing a flow of oxygen-enriched air produced in the higher pressure rectification column into the lower pressure rectification column for separation;at least partially vaporizing a stream of oxygen-enriched liquid air from the higher pressure rectification column through indirect heat exchange with a second stream of purified, compressed, gaseous air to produce resultant vapor, the second stream of purified, compressed, gaseous air thereby being condensed to produce condensed air;warming and then expanding in a turbine with the performance of work, a stream of said resultant vapor;introducing said resultant vapor from the turbine into the lower pressure rectification column; andintroducing a stream of said condensed air into the higher pressure rectification column at an intermediate mass exchange level thereof.