Air separation refrigeration supply method

Abstract

A method of supplying refrigeration to air separation plants within an air separation plant facility in which a refrigerant stream is produced at cryogenic temperature within a centralized refrigeration system. Streams of the refrigerant at the cryogenic temperature are introduced into the air separation plants such that all or a part of the refrigeration requirements of the air separation plants are supplied by the streams of the refrigerant.

We claim: 
     
         1 . A method of supplying refrigeration to air separation plants located within an air separation plant facility, such method comprising:
 separating air within at least two air separation plants to produce products including a nitrogen-rich vapor stream, wherein the air to be separated in the first of the at least two air separation plants comprises a first compressed air stream that is introduced into a liquid expander and subsequently introduced into at least one of a higher pressure column and a lower pressure column of the first of the at least two air separation plants and a second compressed air stream that is expanded to produce an exhaust stream and the exhaust stream is introduced into the higher pressure column, thereby to impart part of the refrigeration requirements of the first of the at least two air separation plants;   withdrawing the nitrogen-rich vapor stream from the first of the at least two air separation plants;   liquefying the nitrogen-rich vapor stream within a refrigeration system to produce a nitrogen-rich liquid refrigerant at a cryogenic temperature as a nitrogen-rich liquid; and   introducing one or more streams of the nitrogen-rich liquid refrigerant, while at the cryogenic temperature, directly from the refrigeration system into the other of the at least two air separation plants such that all or a part of the refrigeration requirements of the other of the at least two air separation plants are supplied by the one or more streams of the nitrogen-rich liquid refrigerant.   
     
     
         2 . The method of  claim 1 , wherein the refrigeration system is operated on an intermittent basis such that liquid production of the air separation plants is increased during operation of the refrigeration system. 
     
     
         3 . The method of  claim 1 , wherein the nitrogen-rich vapor stream is liquefied in the refrigeration system by compressing and cooling a portion of the nitrogen-rich vapor contained within the nitrogen-rich vapor stream and refrigeration for the cooling is generated at least in part by expanding another portion of the nitrogen-rich vapor within a turbo expander. 
     
     
         4 . The method of  claim 1 , wherein:
 the nitrogen-rich vapor is produced as a column overhead of the lower pressure column of the first of the air separation plants;   the nitrogen-rich vapor stream is fully warmed within a main heat exchanger of the first of the air separation plants; and   at least one of the nitrogen-rich liquid refrigerant streams is introduced into the first of the air separation plants as reflux to the higher pressure column.   
     
     
         5 . The method of  claim 4 , wherein:
 an oxygen-rich liquid stream is pumped to produce a pumped liquid oxygen stream;   at least part of the pumped liquid oxygen stream is vaporized or pseudo vaporized within the main heat exchanger through indirect heat exchange with the first compressed air stream.   
     
     
         6 . A method of supplying refrigeration to air separation plants located within an air separation plant facility, such method comprising:
 separating air within the air separation plants to produce products including a nitrogen-rich vapor stream, wherein the air to be separated in the first of the air separation plants comprises a first compressed air stream that is introduced into a liquid expander and introduced into at least one of a higher pressure column and a lower pressure column of the first of the air separation plants and a second compressed air stream that is expanded to produce an exhaust stream and the exhaust stream is introduced into the higher pressure column, thereby to impart part of the refrigeration requirements of the first of the air separation plants;   withdrawing the nitrogen-rich vapor stream from at least one of the air separation plants;   liquefying the nitrogen-rich vapor stream within a refrigeration system to produce a nitrogen-rich liquid refrigerant at a cryogenic temperature as a nitrogen-rich liquid; and   introducing one or more streams of the nitrogen-rich liquid refrigerant, while at the cryogenic temperature, into the air separation plants such that all or a part of the refrigeration requirements of the air separation plants are supplied by the one or more streams of the nitrogen-rich liquid refrigerant to increase liquid production and at least one of the nitrogen-rich liquid refrigerant streams is introduced into the first of the air separation plants as reflux to the higher pressure column;   wherein the nitrogen-rich vapor is produced as a column overhead of the lower pressure column of the first of the air separation plants and the nitrogen-rich vapor stream is fully warmed within a main heat exchanger of the first of the air separation plants;   wherein an oxygen-rich liquid stream is pumped to produce a pumped liquid oxygen stream and at least part of the pumped liquid oxygen stream is vaporized or pseudo vaporized within the main heat exchanger through indirect heat exchange with a compressed air stream; and   wherein the compressed air stream after the indirect heat exchange is introduced into a liquid expander and introduced into at least one of the higher pressure column and the lower pressure column, thereby to impart part of the refrigeration requirements of the at least first of the air separation plants.