Method and installation for producing carbon monoxide by cryogenic distillation

Abstract

The invention relates to a method for producing carbon monoxide by cryogenic distillation. Said method comprises the following steps: a gaseous mixture ( 1 ) containing carbon monoxide, hydrogen and nitrogen is cooled and partially condensed to produce a cooled and partially condensed gaseous mixture; the cooled and partially condensed gaseous mixture ( 5 ) is separated in order to produce a gas enriched with hydrogen and a liquid enriched with carbon monoxide ( 11 ); a flow of the liquid enriched with carbon monoxide is sent to a product stripper ( 17 ) in order to produce hydrogen-depleted liquid carbon monoxide ( 19 ) and hydrogen-enriched gaseous carbon monoxide (RSD); a flow of the hydrogen-depleted carbon monoxide is sent to a first intermediate level of a distillation column ( 23 ); a liquid flow enriched with methane ( 27 ) compared to the flow supplied to the distillation column is drawn off from the bottom of the distillation column; a flow ( 29 ) enriched with carbon monoxide is drawn off at a second intermediate point above the first intermediate point; and a flow (RSDN2) enriched with nitrogen and optionally hydrogen compared to the flow supplied to the distillation column is drawn off from the top of the distillation column.

1 - 8 . (canceled)  
   
   
       9 . A method for producing carbon monoxide by cryogenic distillation comprising the following steps: 
 a) a gas mixture containing carbon monoxide, hydrogen and nitrogen is cooled and partially condensed to produce a cooled and partially condensed gas mixture;    b) the cooled and partially condensed gas mixture is separated to produce a hydrogen-enriched gas and a carbon monoxide-enriched liquid;    c) a stream of the carbon monoxide-enriched liquid is sent to a stripping column to produce hydrogen-free liquid carbon monoxide and hydrogen-enriched carbon monoxide gas;    d) a stream of the hydrogen-free carbon monoxide is sent to a first intermediate level of a distillation column;    e) a liquid stream, richer in methane compared to the stream feeding to the distillation column, is withdrawn from the bottom of the distillation column;    f) a carbon monoxide-rich stream is withdrawn from a second intermediate point, the second intermediate point being above the first intermediate point; and    g) a stream, enriched with nitrogen and optionally hydrogen compared to the stream feeding to the distillation column, is withdrawn from the top of the distillation column.    
   
   
       10 . The method of  claim 9 , in which the carbon monoxide-rich stream withdrawn from the distillation column is a liquid stream.  
   
   
       11 . The method of  claim 9 , in which a carbon monoxide cycle cools the top of the distillation column and/or heats the bottom of the distillation column and/or heats the bottom of the stripping column.  
   
   
       12 . The method of  claim 9 , in which cycle carbon monoxide is expanded in a turbine.  
   
   
       13 . An installation for producing carbon monoxide by cryogenic distillation comprising: 
 a) a heat exchanger for cooling and partially condensing a gas mixture containing carbon monoxide, hydrogen and nitrogen to produce a cooled and partially condensed gas mixture;    b) a separator for separating the cooled and partially condensed gas mixture to produce a hydrogen-enriched gas and a carbon monoxide-enriched liquid;    c) means for conveying the cooled and partially condensed gas mixture from the heat exchanger to the separator;    d) a stripping column and means for conveying at least part of the carbon monoxide-enriched liquid thereto;    e) means for withdrawing a hydrogen-enriched gas from the top of the stripping column and means for withdrawing a hydrogen-free liquid from the bottom of the stripping column; and    f) a distillation column, means for sending a stream of the hydrogen-free liquid to a first intermediate point of the distillation column, means for withdrawing a bottom liquid from the distillation column, means for withdrawing an overhead gas (RSD N2) from the distillation column and means for withdrawing an intermediate fluid at a second intermediate point of the distillation column, the second intermediate point being above the first intermediate point.    
   
   
       14 . The installation of  claim 13 , in which the distillation column has a top condenser and/or a bottom reboiler.  
   
   
       15 . The installation of  claim 13 , in which the stripping column has a bottom reboiler.  
   
   
       16 . The installation of  claim 13 , in which the column (columns) is (are) heated and/or cooled using a carbon monoxide gas cycle.