Apparatus and process for oxygen recovery

Abstract

An apparatus and process for liquid oxygen production can be configured to avoid use of a feed compressor and a recycle compressor. Embodiments can be configured for open loop operation so that a relatively low yield liquid oxygen recovery can be obtained from a feed output from an electrolyzer that is comprised mostly of oxygen (e.g. at least 80 volume percent oxygen, between 80 vol % and 100 vol % oxygen, etc.). The relatively low yield liquid oxygen recovery can be surprisingly provided to permit an advantageous recovery of oxygen to limit waste oxygen that may ultimately be vented while also minimizing equipment and power requirements for the liquid oxygen recovery.

What is claimed is: 
     
         1 . An apparatus for liquid oxygen production, the apparatus comprising:
 a purification unit positioned to receive a feed from at least one electrolyzer and output the feed as a purified feed, the feed comprising oxygen, the feed having a pressure that is within a pre-selected feed pressure range;   a heat exchanger positioned to receive at least a portion of the purified feed outputtable from the purification unit to cool the purified feed and output at least one stream of cooled purified feed;   a first expander positioned to receive at least a first stream of cooled purified feed of the at least one stream of cooled purified feed outputtable from the heat exchanger to expand the first stream of cooled purified feed and output an expanded purified feed stream;   a first phase separator positioned to receive the expanded purified feed stream to form a first liquid oxygen (LOX) stream and a first oxygen vapor stream to feed the first oxygen vapor stream to the heat exchanger as a cooling medium for the heat exchanger.   
     
     
         2 . The apparatus of  claim 1 , wherein the oxygen is between 90 volume percent (vol %) of the feed and 100 vol % of the feed and the pressure that is within the pre-selected feed pressure range is a pressure between 5 bar absolute (bara) and 50 bara. 
     
     
         3 . The apparatus of  claim 1 , comprising a second phase separator that is positioned so that a second purified feed stream of the at least one stream of cooled purified feed outputtable from the heat exchanger is feedable to the second phase separator for formation of a second oxygen vapor stream and a second LOX stream, the second phase separator connected to the heat exchanger so that the second oxygen vapor stream is feedable to the heat exchanger as a cooling medium to cool the purified feed fed to the heat exchanger before the second oxygen vapor stream is vented. 
     
     
         4 . The apparatus of  claim 3 , comprising:
 a second expander positioned to receive the first oxygen vapor stream from the heat exchanger after the first oxygen vapor stream is warmed from passing through the heat exchanger as a second expander feed stream to expand the first oxygen vapor stream for feeding to the heat exchanger as an expanded cooling medium stream.   
     
     
         5 . The apparatus of  claim 1 , comprising:
 a second expander positioned to receive the first oxygen vapor stream from the heat exchanger after the first oxygen vapor stream is warmed from passing through the heat exchanger as a second expander feed stream to expand the first oxygen vapor stream for feeding to the heat exchanger as an expanded cooling medium stream.   
     
     
         6 . The apparatus of  claim 1 , comprising a first compander, wherein the first expander is an expander of the first compander and the first compander also has at least one first compression stage positioned to compress at least a portion of the purified feed stream to a pre-selected cooling feed pressure before it is fed to the heat exchanger, the first expander being interconnected to the at least one first compression stage such that expansion of the first stream of the cooled purified feed outputtable from the heat exchanger at least partially powers compression of the at least one first compression stage of the compander. 
     
     
         7 . The apparatus of  claim 1 , wherein the at least a portion of the purified feed outputtable from the purification unit includes a first stream of the purified feed and a second stream of the purified feed, the apparatus also comprising:
 a first compander, wherein the first expander is an expander of the first compander and the first compander also has at least one first compression stage positioned to compress the first stream of the purified feed before it is fed to the heat exchanger, the first expander being interconnected to the at least one first compression stage such that expansion of the first stream of cooled purified feed outputtable from the heat exchanger at least partially powers compression of the at least one first compression stage of the compander.   
     
     
         8 . The apparatus of  claim 7 , comprising:
 a second expander positioned to receive the first oxygen vapor stream from the heat exchanger after the first oxygen vapor stream is warmed from passing through the heat exchanger as a second expander feed stream to expand the first oxygen vapor stream for feeding to the heat exchanger as an expanded cooling medium stream.   
     
     
         9 . The apparatus of  claim 8 , comprising:
 a second phase separator that is positioned so that the second purified feed stream output from the heat exchanger is feedable to the second phase separator for formation of a second oxygen vapor stream and a second LOX stream, the second phase separator connected to the heat exchanger so that the second oxygen vapor stream is feedable to the heat exchanger as a cooling medium to cool the purified feed fed to the heat exchanger before the second oxygen vapor stream is vented.   
     
     
         10 . The apparatus of  claim 1 , wherein the at least a portion of the purified feed outputtable from the purification unit includes a first stream of the purified feed and a second stream of the purified feed, the apparatus also comprising:
 a first compander, wherein the first expander is an expander of the first compander and the first compander also has at least one first compression stage positioned to compress the first stream of the purified feed before it is fed to the heat exchanger or the second stream of the purified feed, the first expander being interconnected to the at least one first compression stage such that expansion of the first expander at least partially powers compression of the at least one first compression stage of the compander;   a second expander positioned to receive the first oxygen vapor stream from the heat exchanger after the first oxygen vapor stream is warmed from passing through the heat exchanger or positioned to receive the second stream of the purified feed as a second expander feed stream to expand the stream for feeding to the heat exchanger as an expanded cooling medium stream;   a second compander, wherein the second expander is an expander of the second compander and the second compander also has at least one second compression stage positioned to compress the first stream of the purified feed before it is fed to the heat exchanger or the second stream of the purified feed, the second expander being interconnected to the at least one second compression stage such that expansion of the second expander at least partially powers compression of the at least one second compression stage of the compander.   
     
     
         11 . The apparatus of  claim 1 , wherein the apparatus is positioned and configured to form LOX from the feed at a yield of between 5% and 35% without a feed compressor and/or without a recycle compressor. 
     
     
         12 . The apparatus of  claim 1 , wherein the apparatus is positioned and configured as an open loop arrangement for the feed that only uses fluid from the feed as a cooling medium for the heat exchanger. 
     
     
         13 . The apparatus of  claim 1 , comprising:
 a second expander positioned to receive a bypass portion of the purified feed outputtable from the purification unit to expand the bypass portion for feeding to the heat exchanger as a cooling medium; and   the heat exchanger positioned to receive a first stream of the purified feed outputtable from the purification unit to cool the first stream of the purified feed and output the first stream of the purified feed for feeding to the first expander.   
     
     
         14 . The apparatus of  claim 1 , wherein the at least a portion of the purified feed outputtable from the purification unit or the at least one stream of cooled purified feed outputtable from the heat exchanger includes a first stream of the purified feed and a second stream of the purified feed, wherein the first phase separator is positioned such that the second stream of the purified feed is outputtable from the heat exchanger to bypass the first expander for being fed to the first phase separator while the first stream of the purified feed is outputtable from the heat exchanger as the first stream of cooled purified feed for being fed to the first expander. 
     
     
         15 . A process for forming liquid oxygen (LOX) from a feed output from at least one electrolyzer, the feed comprising oxygen, the feed being at a pressure that is within a pre-selected feed pressure range, the process comprising:
 receiving the feed and purifying the feed to form a purified feed;   cooling at least a portion of the purified feed via a heat exchanger and at least one expander to form a cooled feed;   separating the cooled feed to form at least one stream of LOX and at least one stream of oxygen vapor;   feeding each stream of the at least one stream of oxygen vapor to the heat exchanger as a cooling medium for cooling the purified feed.   
     
     
         16 . The process of  claim 15 , wherein the feed comprises oxygen, the oxygen being between 90 volume percent (vol %) of the feed and 99 vol % of the feed and the pressure that is within the pre-selected feed pressure range is a pressure between 5 bar absolute (bara) and 50 bara. 
     
     
         17 . The process of  claim 15 , wherein the at least one expander includes a first expander, the process comprising:
 compressing at least a portion of the feed via at least one first compression stage of a first compander, the first expander being an expander of the first compander, the first expander being interconnected to the at least one first compression stage of the first compander such that expansion of at least a portion of the purified feed at least partially powers compression of the at least a portion of the feed provided by the at least one first compression stage.   
     
     
         18 . The process of  claim 15 , wherein the at least one stream of LOX is formed from the feed at a yield of between 5% and 35% without a feed compressor and/or without a recycle compressor. 
     
     
         19 . The process of  claim 15 , comprising:
 outputting the at least one stream of oxygen vapor from the heat exchanger as a warmed at least one stream of oxygen vapor for venting and/or use as a regeneration gas.   
     
     
         20 . The process of  claim 19 , wherein the process is an open loop arrangement for the feed that only uses fluid from the feed as the cooling medium for the heat exchanger. 
     
     
         21 . The process of  claim 15 , wherein the feed is not compressed to a higher pressure via a feed compressor and the at least one stream of oxygen vapor is not compressed to a higher pressure via a recycle compressor. 
     
     
         22 . The process of  claim 15 , wherein:
 the cooling of at least a portion of the purified feed via the heat exchanger and at least one expander comprises:
 splitting the purified feed into a first stream of purified feed and a bypass stream of purified feed and feeding the first stream of the purified feed to the heat exchanger to undergo cooling therein and feeding the bypass stream of the purified feed to an expander to undergo expansion so that the expanded bypass stream of the purified feed is feedable to the heat exchanger as a cooling medium; and 
   the separating of the cooled feed to form the at least one stream of LOX and the at least one stream of oxygen vapor includes feeding the first stream of purified feed from the heat exchanger to a phase separator for forming a first stream of LOX and a first stream of oxygen vapor; and   the feeding each stream of the at least one stream of oxygen vapor to the heat exchanger as a cooling medium for cooling the purified feed includes feeding the first stream of oxygen vapor to the heat exchanger as a cooling medium.   
     
     
         23 . An apparatus for liquid oxygen production, the apparatus comprising:
 a purification unit positioned to receive a feed from at least one electrolyzer and output the feed as a purified feed, the feed comprising oxygen, the feed having a pressure that is within a pre-selected feed pressure range;   a heat exchanger positioned to receive at least a portion of the purified feed outputtable from the purification unit to cool the purified feed and output at least one stream of cooled purified feed;   a first expander positioned to receive at least a first stream of cooled purified feed of the at least one stream of cooled purified feed outputtable from the heat exchanger or a portion of the purified feed to expand it and output an expanded purified feed stream to feed to the heat exchanger as a cooling medium;   a first phase separator positioned to receive a first stream of the at least one stream of cooled purified feed outputtable from the heat exchanger or a second stream of the at least one stream of cooled purified feed outputtable from the heat exchanger to form a first liquid oxygen (LOX) stream and a first oxygen vapor stream to feed the first oxygen vapor stream to the heat exchanger as a cooling medium for the heat exchanger.