Process and Apparatus for Nitrogen Production

摘要

A process and apparatus for producing nitrogen by which product nitrogen can be efficiently supplied. The nitrogen producing process comprises: a first separation step in which feed air is distilled at a low temperature; a first indirect heat exchange step in which a first nitrogen gas and a first oxygen-enriched liquefied fluid which have been separated in the first separation step are subjected to indirect heat exchange to obtain a first liquefied nitrogen and a first oxygen-enriched gas fluid; a second separation step in which the first oxygen-enriched gas fluid is distilled at a low temperature; a second indirect heat exchange step in which a second nitrogen gas and a second oxygen-enriched liquefied fluid which have been separated in the second separation step are subjected to indirect heat exchange to obtain a second liquefied nitrogen and a second oxygen-enriched gas fluid; a cold generating step in which the second oxygen-enriched gas fluid is adiabatically expanded to generate cold; a first product recovery step in which part of the first nitrogen gas is discharged as a first product nitrogen gas; and a second product recovery step in which part of the second nitrogen gas is discharged as a second product nitrogen gas after the cold is recovered.