Cryogenic purification with heat uptake

Abstract

Process for purifying a gaseous feed stream using an adsorption unit comprising at least two adsorbers, a cryogenic distillation unit, an exchanger and a compressor operating at a temperature less than or equal to −50° C., in which the heat necessary for the regeneration of the adsorbers is derived, at least partly, from at least one portion of the heat generated by the compressor, during the compression of a fluid.

1 - 8 . (canceled) 
     
     
         9 . A process for purifying a feed gas stream using an adsorption unit comprising at least  2  adsorbers, a cryogenic distillation unit, an exchanger and a compressor operating at a temperature below or equal to −50° C., wherein the heat needed for the regeneration of the adsorbers is derived, at least in part, from at least one portion of the heat generated by the compressor, during the compression of a fluid and said process comprises an adsorption step implemented by the adsorption unit, with the adsorption step performed at a negative temperature. 
     
     
         10 . The purification process as claimed in  claim 9 , wherein the process comprises the following successive steps:
 a) cooling the feed gas stream in the exchanger to a temperature below −50° C.;   b) sending the cooled gas stream to the adsorption unit wherein at least one impurity X is at least partly adsorbed so as to recover a gas stream depleted in impurity X;   c) introducing the gas stream depleted in impurity X into the exchanger in order to be cooled to a temperature below −50° C.;   d) sending the gas stream depleted in impurity X and cooled to the cryogenic distillation unit wherein it is separated into at least a first stream and a second stream;   e) introducing a portion of the first stream into the exchanger in order to be reheated to a temperature above −150° C. before being compressed in the compressor with a compression ratio greater than 1.2;   f) sending the compressed first stream to the adsorption unit in order to regenerate one of the two adsorbers;   
       with the compression in step e) leading to a temperature increase of the first stream of at least 20° C. and thus providing the heat input needed for the regeneration of at least one of the adsorbers. 
     
     
         11 . The purification process as claimed in  claim 9 , wherein the process comprises the following successive steps:
 a) cooling the feed gas stream in the exchanger to a temperature below −50° C.;   b) sending the cooled gas stream to the adsorption unit wherein at least one impurity X is at least partly adsorbed so as to recover a first stream depleted in impurity X;   c) compressing the gas stream depleted in impurity X in the compressor with a compression ratio greater than 1.2 before being cooled in the exchanger to a temperature below −50° C.;   d) sending the gas stream depleted in impurity X, compressed and cooled to the cryogenic distillation unit wherein it is separated into at least a first stream and a second stream;   e) introducing a portion of the first stream is introduced into the exchanger in order to be reheated to a temperature above −150° C.;   f) sending the reheated first stream to the adsorption unit in order to regenerate at least one of the two adsorbers;   
       with the compression in step c) leading to a temperature increase of the gas stream depleted in compound X of 20° C. and thus providing, indirectly via the exchanger, the heat input needed for the reheating of a portion of the first stream and therefore for the regeneration of at least one of the two adsorbers in step f). 
     
     
         12 . The process of  claim 9 , wherein the adsorbers comprise a monobed. 
     
     
         13 . The process of  claim 9 , wherein the feed gas stream is air and the impurity X is selected from the group consisting of H 2 O, CO 2 , N 2 O, C n H m , and NOx. 
     
     
         14 . The process of  claim 9 , wherein the feed gas stream comprises water and the process further comprises, before step a), a step of pre-purification of the feed gas stream that makes it possible to eliminate at least one portion of the water. 
     
     
         15 . The process of  claim 14 , wherein the pre-purification step is carried out by adsorption at ambient temperature. 
     
     
         16 . The process of  claim 15 , wherein the adsorption of the pre-purification step is carried out on a monobed of alumina, silica gel or molecular sieve type.