Method for recovering gaseous nitrogen from the waste nitrogen stream of an air separation unit

Abstract

The method for the production of nitrogen can include the steps of a) providing a waste nitrogen gas stream at a first pressure called low pressure, wherein the waste nitrogen gas originates from a low pressure column of a cryogenic air separation unit; b)compressing the waste nitrogen gas stream to a second pressure in a waste nitrogen compressor to produce a pressurized nitrogen stream; and c) introducing the pressurized nitrogen stream to a nitrogen generator under conditions effective for producing a purified nitrogen product, wherein the purified nitrogen product has a higher concentration of nitrogen as compared to the pressurized nitrogen stream.

We claim: 
     
         1 . A method for the production of nitrogen, the method comprising the steps of:
 a) providing a waste nitrogen gas stream at a first pressure called low pressure, wherein the waste nitrogen gas originates from a low pressure column of a cryogenic air separation unit;   b) compressing the waste nitrogen gas stream to a second pressure in a waste nitrogen compressor to produce a pressurized nitrogen stream; and   c) introducing the pressurized nitrogen stream to a nitrogen generator under conditions effective for producing a purified nitrogen product, wherein the purified nitrogen product has a higher concentration of nitrogen as compared to the pressurized nitrogen stream.   
     
     
         2 . The method as claimed in  claim 1 , wherein the method further comprises an absence of a purification step for the waste nitrogen gas stream. 
     
     
         3 . The method as claimed in  claim 1 , wherein the waste nitrogen gas stream consists essentially of nitrogen and impurities, wherein the impurities comprise an absence of water and carbon dioxide. 
     
     
         4 . The method as claimed in  claim 1 , wherein a portion of the purified nitrogen product is expanded in a turbine to provide cooling for the nitrogen generator. 
     
     
         5 . The method as claimed in  claim 1 , wherein a portion of the purified nitrogen product is recycled back to the waste nitrogen compressor.