Apparatus and process for providing nitrogen and oxygen

Abstract

An apparatus and process for providing nitrogen and oxygen can include a multicolumn tower that includes a lower pressure column (LP) positioned in alignment with an intermediate pressure (MP) column. At least one of these columns and at least one higher pressure (HP) column can receive air from a feed intake system. Embodiments can be adapted so that the diameter of the LP and MP columns are similar, if not the same so that the columns can be aligned with each other in the tower. Embodiments can be adapted to allow for high purity nitrogen recovery from at least one HP column while also obtaining at least one oxygen stream from the LP column with equipment that has an overall lower height, or length, that can be easier to fabricate and install.

What is claimed is: 
     
         1 . A process for providing nitrogen and oxygen comprising:
 splitting a feed of air for feeding some of the air to a first column and some of the air to a second column, the first column operating at a first pressure range and the second column operating at a second pressure range, the first pressure range being a higher pressure range than the second pressure range;   feeding a stream of crude oxygen to a third column, the crude oxygen being comprised of at least a portion of a crude oxygen stream output from the first column and/or at least a portion of a crude oxygen stream output from the second column, the third column operating at a third pressure range, the third pressure range being a lower pressure range than the second pressure range;   outputting a nitrogen-enriched vapor stream from the second column and feeding the nitrogen-enriched vapor stream output from the second column to an expander to be expanded therein;   feeding the expanded nitrogen-enriched vapor stream to a heat exchanger as a refrigerant for pre-cooling the air being fed to the first column and the second column; and   outputting a nitrogen-rich stream from the first column or a fourth column that is fluidly connected to the first column and operates at a fourth pressure range that is greater than the second pressure range; and   outputting an oxygen product stream from the third column.   
     
     
         2 . The process of  claim 1 , wherein the nitrogen-rich stream is output from the first column and comprises between 98.5 mole percent (mol %) nitrogen and 100 mol % nitrogen. 
     
     
         3 . The process of  claim 1 , wherein the nitrogen-rich stream is output from the fourth column, the process also comprising:
 the first column outputting a nitrogen-enriched vapor stream such that a first portion of the nitrogen-enriched vapor stream output from the first column is fed to the fourth column;   feeding a stream of crude oxygen to the reboiler-condenser of the fourth column, the crude oxygen fed to the fourth column being comprised of a portion of the crude oxygen stream output from the first column and/or a portion of the crude oxygen stream output from the second column.   
     
     
         4 . The process of  claim 3 , comprising:
 feeding a stream comprising vapor output from a reboiler-condenser of the fourth column to an intermediate section of the third column; and/or   feeding a liquid stream output from a bottom portion of the fourth column to the first column and/or the third column as a reflux stream.   
     
     
         5 . The process of  claim 1 , wherein the nitrogen-rich stream is output from the fourth column, the process also comprising:
 the first column outputting a nitrogen-enriched vapor stream such that a first portion of the nitrogen-enriched vapor stream output from the first column is fed to the fourth column;   feeding a portion of the oxygen product stream output from the third column to the reboiler-condenser of the fourth column.   
     
     
         6 . The process of  claim 1 , wherein:
 the first pressure range is between 0.42 MPa and 0.7 MPa,   the second pressure range is between 0.22 MPa and 0.45 MPa, and   the third pressure range is between 0.10 MPa and 0.18 MPa.   
     
     
         7 . The process of  claim 1 , comprising:
 passing at least a portion of a nitrogen-enriched vapor output from the first column to a first reboiler-condenser to condense the nitrogen-enriched vapor, the first reboiler-condenser positioned between the second column and the third column within a vessel shell so that liquid at a bottom portion of the third column is vaporizable via the first reboiler-condenser; and   passing a first portion of the condensed nitrogen-enriched vapor output from the first reboiler-condenser to the first column as a reflux stream for the first column; and   splitting a second portion of the condensed nitrogen-enriched vapor output from the first reboiler-condenser from the first portion of the condensed nitrogen-enriched vapor output from the first reboiler-condenser as a liquid nitrogen (LIN) product stream.   
     
     
         8 . The process of  claim 1 , wherein the outputting of the oxygen product stream from the third column comprises outputting a product stream comprising oxygen from a bottom portion of the third column, the oxygen product stream comprising at least 90 mole percent oxygen. 
     
     
         9 . The process of  claim 8 , comprising:
 passing at least a portion of the oxygen product stream through a heat exchanger to vaporize the portion of the oxygen product stream passed through the heat exchanger.   
     
     
         10 . The process of  claim 1 , wherein the nitrogen-rich stream is output from the fourth column, the process also comprising:
 the first column outputting a nitrogen-enriched vapor stream such that a first portion of the nitrogen-enriched vapor stream is fed to a first reboiler-condenser to condense the first portion of the nitrogen-enriched vapor and a second portion of the nitrogen-enriched vapor stream output from the first column is fed to the fourth column, the first reboiler-condenser positioned between the second column and the third column within a vessel shell so that liquid at a bottom portion of the third column is vaporizable via the first reboiler-condenser for condensing the first portion of the nitrogen-enriched vapor; and   the first reboiler-condenser outputting the condensed first portion of the nitrogen-enriched vapor for feeding to the first column as a reflux stream.   
     
     
         11 . The process of  claim 1 , wherein the feeding of the stream of crude oxygen to the third column comprises:
 feeding at least a portion of the crude oxygen stream output from the first column and/or at least a portion of the crude oxygen stream output from the second column to a second reboiler-condenser for vaporization to form at least one at least partially vaporized crude oxygen stream for feeding to the third column as the stream of crude oxygen.   
     
     
         12 . An apparatus for providing nitrogen and oxygen, comprising:
 a first column configured to operate at a first pressure range, the first column positioned to receive a first column feed of air output from a compression system;   a second column configured to operate at a second pressure range, the second pressure range being a lower pressure range than the first pressure range, the second column positioned to receive a second column feed of air output from the compression system, the second column configured to output a stream of nitrogen-enriched vapor;   a third column positioned to receive at least one stream of crude oxygen via at least one of: a portion of a stream of crude oxygen output from a bottom portion of the first column and/or a portion of a stream of crude oxygen output from a bottom portion of the second column and output an oxygen product stream;   an expander positioned to receive the nitrogen-enriched vapor output from the second column to expand the nitrogen-enriched vapor and feed the expanded nitrogen-enriched vapor to a heat exchanger as a refrigerant, the heat exchanger positioned to pre-cool the air upstream of the first column and the second column.   
     
     
         13 . The apparatus of  claim 12 , wherein the second column and the third column are vertically aligned, have a substantially similar diameter, and are within a vessel shell. 
     
     
         14 . The apparatus of  claim 13 , comprising:
 a first reboiler-condenser positioned within the vessel shell between the second column and the third column, the first reboiler-condenser configured to receive a nitrogen-enriched vapor from the first column to condense the vapor and output the condensed nitrogen-enriched vapor to the first column as a stream of reflux and also boil liquid from a bottom portion of the third column.   
     
     
         15 . The apparatus of  claim 14 , wherein the first column is configured to output a nitrogen-rich stream as a product stream and/or a liquid nitrogen product portion of the stream of reflux is splittable from the stream of reflux to form a liquid nitrogen product stream. 
     
     
         16 . The apparatus of  claim 12 , comprising:
 a first reboiler-condenser positioned within a vessel shell between the second column and the third column, the first reboiler-condenser configured to receive a first portion of a nitrogen-enriched vapor from the first column to condense the vapor and output the condensed nitrogen-enriched vapor to the first column as a stream of reflux and also boil liquid from a bottom portion of the third column;   a fourth column positioned to receive a second portion of the nitrogen-enriched vapor output from the first column;   the fourth column configured to output a nitrogen-rich stream as a product stream.   
     
     
         17 . The apparatus of  claim 16 , wherein a reboiler-condenser of the fourth column is configured to output a liquid nitrogen reflux stream, a portion of the liquid nitrogen reflux stream being splittable from the liquid nitrogen reflux stream outputtable from the reboiler-condenser of the fourth column to form a liquid nitrogen product stream. 
     
     
         18 . The apparatus of  claim 12 , comprising:
 the heat exchanger, the heat exchanger positioned to receive the nitrogen-enriched vapor output from the second column to warm the nitrogen-enriched vapor via cooling of the air fed to the heat exchanger and feed the warmed nitrogen-enriched vapor to the expander to expand the nitrogen-enriched vapor, the heat exchanger also configured and positioned to receive the expanded nitrogen-enriched vapor outputtable from the expander to pre-cool the air.   
     
     
         19 . The apparatus of  claim 12 , comprising:
 a first reboiler-condenser positioned within a vessel shell between the second column and the third column, the first reboiler-condenser configured to receive a nitrogen-enriched vapor from the first column to condense the vapor and output the condensed nitrogen-enriched vapor for feeding to the first column as a stream of reflux; and   a second reboiler-condenser positioned to receive at least one of the stream of crude oxygen output from the bottom portion of the first column and/or the stream of crude oxygen output from the bottom portion of the second column for vaporization to form at least one at least partially vaporized crude oxygen stream for feeding to the third column;   the third column being fluidly connected to the second reboiler-condenser to receive the at least one at least partially vaporized crude oxygen stream as the at least one stream of crude oxygen received via the portion of the stream of crude oxygen output from the bottom portion of the first column and/or the portion of the stream of crude oxygen output from the bottom portion of the second column.   
     
     
         20 . The apparatus of  claim 12 , wherein:
 the first pressure range is between 0.42 MPa and 0.7 MPa,   the second pressure range is between 0.22 MPa and 0.45 MPa, and   the third pressure range is between 0.10 MPa and 0.18 MPa.