Method for separating a synthesis gas

Abstract

A method for separating a synthesis gas containing carbon monoxide and hydrogen including compressing a flow of synthesis gas received from a source of synthesis gas in a compressor, purifying the compressed synthesis gas in a purification unit to purify it of water and/or carbon dioxide, cooling the compressed and purified flow of synthesis gas, separating the cooled flow of synthesis gas by washing and/or distillation at a cryogenic temperature and optionally by adsorption in a separating unit, and producing at least the following three gases in the separating unit: a carbon monoxide-enriched gas, a hydrogen-enriched gas, a residual gas containing carbon monoxide and hydrogen that is less pure with respect to carbon monoxide than the carbon monoxide-enriched gas and less pure with respect to hydrogen than the hydrogen-enriched gas.

1 .- 15 . (canceled) 
     
     
         16 . A method for separating a synthesis gas containing carbon monoxide and hydrogen comprising:
 i) compressing a flow of synthesis gas received from a source of synthesis gas in a compressor,   ii) purifying the compressed synthesis gas in a purification unit to purify it of water and/or carbon dioxide,   iii) cooling the compressed and purified flow of synthesis gas,   iv) separating the cooled flow of synthesis gas by washing and/or distillation at a cryogenic temperature and optionally by adsorption in a separating unit, and   v) producing at least the following three gases in the separating unit: a carbon monoxide-enriched gas, a hydrogen-enriched gas, a residual gas containing carbon monoxide and hydrogen that is less pure with respect to carbon monoxide than the carbon monoxide-enriched gas and less pure with respect to hydrogen than the hydrogen-enriched gas and optionally also a methane-enriched gas, and/or a nitrogen-enriched gas, and   vi) sending at least one part of each of the following gases downstream of the source, only if the flow of synthesis gas received from the source and sent to the compressor is below a threshold or zero, the carbon monoxide-enriched gas, the hydrogen-enriched gas, and the residual gas containing carbon monoxide and hydrogen, to be purified in the purification unit and separated in the separating unit, wherein the at least one part of the three gases is sent upstream of the compressor to be compressed in the compressor upstream of the purification.   
     
     
         17 . The method as claimed in  claim 16 , further comprising:
 a) storing compressed synthesis gas while the flow of synthesis gas received from the source is above the threshold, and   b) sending at least one part of the compressed synthesis gas, previously stored, as well as at least one part of at least each of the first three gases in step v), downstream of the source.   
     
     
         18 . The method as claimed in  claim 16 , wherein at least one part of at least each of the three gases in step v) downstream of the source and upstream of the compressor only if the flow of synthesis gas received from the source is below the threshold, or even if no flow is received from the source. 
     
     
         19 . The method as claimed  claim 16 , wherein only x% of the carbon monoxide-enriched gas, y% of the hydrogen-enriched gas and z% of the residual gas are sent to the separating unit when the flow of synthesis gas received from the source is below a threshold, x, y and z differing by at most 5%. 
     
     
         20 . The method as claimed in  claim 16 , wherein a part of the carbon monoxide-enriched gas is stored in a storage facility and the rest of the carbon monoxide-enriched gas is sent to a customer if the flow of synthesis gas received from the source is above the threshold and the carbon monoxide-enriched gas received from the storage facility is sent to the customer if the flow of synthesis gas is below the threshold. 
     
     
         21 . The method as claimed in  claim 20 , wherein if the flow of synthesis gas received from the source is below the threshold, all the carbon monoxide-enriched gas sent to the customer comes from the storage facility is sent upstream of the compressor and downstream of the source. 
     
     
         22 . The method as claimed in  claim 16 , wherein the synthesis gas is a residual gas from an acetylene production unit. 
     
     
         23 . The method as claimed in  claim 16 , wherein if the flow of synthesis gas received from the source is above the threshold, part of the synthesis gas is stored in a storage facility and if the flow of synthesis gas received from the source is below the threshold, synthesis gas is sent from the storage facility to the compressor. 
     
     
         24 . The method as claimed in  claim 16 , wherein if the flow of synthesis gas received from the source is zero, the separating unit is only supplied with gases produced by the separating unit. 
     
     
         25 . The method as claimed in  claim 16 , wherein the carbon monoxide-enriched gas is compressed in a product compressor and is sent to the customer and if the flow of synthesis gas received from the source is below the threshold and the flow of carbon monoxide-enriched gas to be compressed is below another threshold, gaseous nitrogen is sent to the product compressor to be compressed with the carbon monoxide-enriched gas. 
     
     
         26 . The method as claimed in  claim 16 , wherein if the flow of synthesis gas received from the source is below a threshold, a gas rich in a component of the synthesis gas received from another source, which is not the separating unit, is sent to the separating unit. 
     
     
         27 . The method as claimed in  claim 16 , wherein the carbon monoxide-enriched gas is compressed in a product compressor, then split into two, one compressed part serving as a product and one compressed part being recycled downstream of the source and/or the hydrogen-enriched gas is compressed in a product compressor, then split into two, one compressed part serving as a product and one compressed part being recycled downstream of the source. 
     
     
         28 . The method as claimed in  claim 16 , wherein the residual gas contains methane. 
     
     
         29 . The method as claimed in  claim 16 , wherein the total percentage of hydrogen and carbon monoxide in the residual gas is below 98 mol %. 
     
     
         30 . The method as claimed in  claim 16 , wherein the at least one part of each of the following three gases: the carbon monoxide-enriched gas, the hydrogen-enriched gas and the residual gas containing carbon monoxide and hydrogen are only compressed in the compressor.