Thermally Integrated Process and Apparatus for Purification and Separation of Components of a Synthesis Gas

Abstract

Process for the purification and separation of a synthesis gas stream containing hydrogen, carbon monoxide and carbon dioxide in which synthesis gas is purified in a purification unit (W) involving a methanol washing step to remove carbon dioxide, the carbon dioxide depleted synthesis gas is purified by adsorption (P) to produce a purified synthesis gas stream and the purified gas stream is sent to a cryogenic separation unit (C) where it is cooled and separated by cryogenic separation in a column of a column system, at least one stream ( 13 ) enriched in carbon monoxide is removed from a column of the column system, warmed and divided in two, one part of the stream being removed from the cryogenic separation unit as a first stream, the other part of the stream forming a second stream ( 13 B, 15 B) and being sent to the purification unit wherein it is warmed and the warmed second stream is mixed with the first stream.

1 - 15 . (canceled) 
     
     
         16 . A process for the purification and separation of a synthesis gas stream containing hydrogen, carbon monoxide and carbon dioxide, the method comprising the steps of:
 purifying the synthesis gas in a purification unit using a methanol washing step to remove carbon dioxide to form a carbon dioxide depleted synthesis gas;   purifying the carbon dioxide depleted synthesis gas by adsorption to produce a purified synthesis gas stream;   sending the purified synthesis gas stream to a cryogenic unit where the purified synthesis gas stream is cooled and separated by cryogenic separation in the cryogenic separation unit to produce an enriched carbon monoxide stream; and   dividing the enriched carbon monoxide stream into a first part and a second part, wherein the first part is removed from the cryogenic separation unit to form a first stream, wherein the second part is sent to the purification unit wherein the second part is warmed and then mixed with the first stream.   
     
     
         17 . A process according to  claim 16 , wherein the second part of the enriched carbon monoxide stream is removed from the cryogenic separation unit at a temperature below 20° C. 
     
     
         18 . A process according to  claim 17 , wherein the second part of the enriched carbon monoxide stream is removed from the cryogenic separation unit at a temperature above −65° C. 
     
     
         19 . A process according to  claim 16 , wherein the second part of the enriched carbon monoxide stream is warmed in the purification unit to a temperature between −40° C. and 40° C. and then mixed with the first stream within the cryogenic separation unit. 
     
     
         20 . A process according to  claim 16 , wherein the second part of the enriched carbon monoxide stream is warmed against the synthesis gas upstream of the methanol wash column. 
     
     
         21 . A process according to  claim 16 , wherein the second part of the enriched carbon monoxide stream is warmed against an intermediate liquid side-stream or bottom liquid stream from the methanol wash column. 
     
     
         22 . A process according to  claim 16 , wherein the second part of the enriched carbon monoxide stream is warmed against carbon dioxide depleted synthesis gas from the methanol wash column. 
     
     
         23 . A process according to  claim 16 , wherein the second part of the enriched carbon monoxide stream is warmed against a stream removed from a flash column of the purification unit. 
     
     
         24 . An apparatus for the purification and separation of a synthesis gas stream containing hydrogen, carbon monoxide and carbon dioxide, the apparatus comprising:
 a purification unit comprising a methanol washing column and a heat exchanger, the purification unit configured to purify the synthesis gas to remove carbon dioxide;   an adsorption unit in fluid communication with the purification unit and configured to receive the synthesis gas from the purification unit and provide further purification to produce a purified synthesis gas stream;   a cryogenic separation unit in fluid communication with the adsorption unit and configured to receive the purified synthesis gas stream from the adsorption unit and cool and separate the purified synthesis gas stream to form an enriched carbon monoxide stream and a hydrogen enriched stream, the cryogenic separation unit comprising a column system and a heat exchange line; the heat exchange line configured to warm the enriched carbon monoxide stream and the hydrogen enriched stream;   means for dividing the enriched carbon monoxide stream into a first stream and a second stream, wherein the heat exchanger of the purification unit is configured to receive the second stream from the cryogenic separation unit; and   means for removing the second stream from the heat exchanger and mixing the second stream with the first stream.   
     
     
         25 . The apparatus according to  claim 24 , wherein the apparatus is configured such that the heat exchanger of the purification unit receives the second stream at a temperature between −65° C. and 20° C. 
     
     
         26 . The apparatus according to  claim 24 , comprising a means for sending to the heat exchanger synthesis gas upstream of the methanol wash column of the purification unit. 
     
     
         27 . The apparatus according to  claim 24 , comprising a means for sending to the heat exchanger of the purification unit an intermediate liquid side-stream from the methanol wash column. 
     
     
         28 . The apparatus according to  claim 24 , comprising a means for sending to the heat exchanger of the purification unit a bottom liquid stream from the methanol wash column. 
     
     
         29 . The apparatus according to  claim 24 , comprising a means for sending to the heat exchanger of the purification unit carbon dioxide depleted synthesis gas from the methanol wash column. 
     
     
         30 . The apparatus according to  claim 24 , wherein the purification unit includes a flash column and means for sending liquid from the methanol wash column to the flash column and means for sending a stream removed from the flash column to the heat exchanger of the purification unit.