Unit for separating a mixture of carbon monoxide, hydrogen and methane by cryogenic distillation

Abstract

A unit for separating a mixture of carbon monoxide, hydrogen and methane by cryogenic distillation including a distillation column having a condenser and a reboiler, a refrigeration cycle having a compressor, a first heat exchanger, a second heat exchanger, means for sending the gas mixture to be cooled in the first heat exchanger, means for separating the gas mixture cooled in the first heat exchanger and for sending a fluid produced by the separation to the distillation column, a thermally insulated enclosure containing the first and second heat exchangers, means for sending a cycle gas from the distillation column to the second heat exchanger and then to the first heat exchanger to be heated, means for sending a cycle gas liquefied in the reboiler to be cooled in the second heat exchanger, and means for sending the cycle gas liquefied and cooled in the second heat exchanger to the condenser.

What is claimed is: 
     
         1 . A unit for separating a mixture of carbon monoxide, hydrogen and methane by cryogenic distillation comprising;
 at least one distillation column comprising a top condenser and a bottom reboiler,   a refrigeration cycle comprising a cycle compressor,   a first heat exchanger,   a second heat exchanger,   a means for sending the gas mixture to be cooled in at least the first heat exchanger,   a means for separating the gas mixture cooled in at least the first heat exchanger and for sending a fluid produced by the separation to the at least one distillation column,   a thermally insulated enclosure containing the first and second heat exchangers but no scrubbing or distillation column, the thermally insulated enclosure having a length,   a means for sending a cycle gas from the at least one distillation column to the second heat exchanger to be heated and then to the first heat exchanger to be heated,   a means for sending a cycle gas liquefied in the bottom reboiler to be cooled in the second heat exchanger, and   a means for sending the cycle gas liquefied and cooled in the second heat exchanger to the top condenser,   
       wherein the thermally insulated enclosure (is arranged when in use with the length oriented vertically and the first heat exchanger being arranged beside the second heat exchanger. 
     
     
         2 . The unit according to  claim 1 , wherein the second heat exchanger has a first end and a second end and is connected such that in operation at least one fluid to be heated is sent to the first end and exits from the second end and/or at least one fluid to be cooled is sent to the second end and exits at the first end, the first end being located at a geodesic height greater than the geodesic height of the second end. 
     
     
         3 . The unit according to  claim 1 , wherein the first heat exchanger has a first end at a first geodesic height and a second end at a second geodesic height less than the first geodesic height and is connected such that in operation at least one fluid to be heated is sent to the end at the second height and exits from the end at the first height and/or at least one fluid to be cooled is sent to the end at the first height and exits at the end at the second height. 
     
     
         4 . The unit according to  claim 2 , wherein a pipe is connected to the second end of the second heat exchanger and to the end of the first exchanger at the second geodesic height to transfer a fluid to be heated from the second exchanger to the first exchanger. 
     
     
         5 . The unit according to  claim 2 , wherein a pipe is connected to the second end of the second heat exchanger and to the end of the first exchanger at the second geodesic height to transfer a fluid to be cooled from the first exchanger to the second exchanger. 
     
     
         6 . The unit according to  claim 2 , wherein the second end of the second exchanger is substantially at the second geodesic height. 
     
     
         7 . The unit according to  claim 1 , wherein the first and second exchangers are located in use in an upper part of the enclosure. 
     
     
         8 . The unit according to  claim 7 , wherein other elements of the unit required to operate at a cryogenic temperature are located in a lower part of the enclosure. 
     
     
         9 . The unit according to  claim 1  comprising a third heat exchanger which is located in the thermally insulated enclosure. 
     
     
         10 . The unit according to  claim 9 , wherein the third heat exchanger is located in use in a lower part of the enclosure. 
     
     
         11 . The unit according to  claim 10 , wherein the third heat exchanger is located in use below the second heat exchanger.