Patent ID: 8161771

Claim:
A method of separating a nitrogen product from a compressed and purified feed stream comprising nitrogen and oxygen, said method comprising: separating the nitrogen from the compressed and purified feed stream within a distillation column of a cryogenic rectification plant to produce a nitrogen-rich vapor column overhead and an oxygen-rich liquid column; generating reflux for the distillation column within the cryogenic rectification plant by condensing a portion of the nitrogen-rich vapor within a down-flow heat exchanger associated with the distillation column through indirect heat exchange with a combined oxygen-rich liquid stream, thereby partially vaporizing the combined oxygen-rich liquid into an Oxygen-rich liquid phase and an oxygen-rich vapor phase; and introducing an oxygen-rich liquid column bottoms stream composed of the oxygen-rich liquid column bottoms into an ejector as a motive fluid and drawing a stream of the oxygen-rich liquid phase into the ejector and into the oxygen-rich liquid column bottoms stream, thereby to form the combined oxygen-rich stream; and discharging the combined oxygen-rich stream from the ejector to the down-flow heat exchanger thereby to recirculate part of the oxygen-rich liquid phase thereto, the combined oxygen-rich stream being discharged from the ejector at a pressure sufficient to condense the nitrogen-rich vapor within the down-flow heat exchanger.