Method for Producing a Hydrogen-Enriched Gas Stream from Hydrogenated Gas Streams Comprising Hydrocarbons

Abstract

The invention concerns a method for producing a hydrogen-enriched gas stream from at least one gas stream comprising for the major part hydrogen and a gas stream comprising hydrogen and hydrocarbons, using a pressure-modulated gas adsorption unit, the temperature of the gas stream comprising hydrogen and hydrocarbons being first lowered so as to condense the hydrocarbons.

1 - 7 . (canceled) 
   
   
       8 . A process for producing a hydrogen-enriched gas stream and a liquefied petroleum gas from at least one gas stream mainly comprising hydrogen at pressure P and a gas stream comprising hydrogen and hydrocarbons, in which the following steps are carried out:
 during step a), the gas stream comprising hydrogen and hydrocarbons is adjusted to the pressure P;   during step b), the gas stream comprising hydrogen and hydrocarbons and adjusted to the pressure P is treated in a pressure swing gas adsorption unit fed will the gas stream mainly comprising hydrogen and having a pressure P so as to supply:
 at a first outlet, the hydrogen-enriched gas stream having a hydrogen concentration greater than that of the gas stream mainly comprising hydrogen; and 
 at a second outlet, a waste stream 
   
     characterized in that between step a) and step b), the temperature of the gas stream comprising hydrogen and hydrocarbons and adjusted to the pressure P is lowered so as to condense the hydrocarbons and form the liquid petroleum gas. 
   
   
       9 . The process of  claim 8 , wherein the gas stream mainly comprising hydrogen has a hydrogen concentration between 50 and 99 vol %. 
   
   
       10 . The process of  claim 8 , wherein the gas stream comprising hydrogen and hydrocarbons has a hydrogen concentration at least 10% lower relative to the value of the hydrogen concentration of the gas stream mainly comprising hydrogen. 
   
   
       11 . The process of  claim 8 , wherein the gas stream comprising hydrogen and hydrocarbons has a hydrocarbon concentration between 10 and 50 vol %. 
   
   
       12 . The process of  claim 8 , wherein the gas separation unit is a pressure swing adsorption (PSA) unit combined with an integrated compressor, in which, for each adsorber of the unit, a pressure swing cycle is carried out comprising a succession of phases which define the phases of adsorption, decompression, purge and pressure rise, such that:
 during the adsorption phase:
 during a first step, the gas stream mainly comprising hydrogen and having a pressure P is brought into contact with the bed of the adsorber; and 
 during a second step, introduced into contact with the bed of the adsorber is the mixture of pressure P whose temperature has been lowered so as to condense the hydrocarbons and that is composed of:
 on the one hand, the gas stream comprising hydrogen and hydrocarbons; and 
 on the other hand, the PSA recycle gas, 
 
  so as to adsorb the compounds other than hydrogen and to produce, at the top of the adsorber bed, the enriched stream having a hydrogen concentration greater than that of the gas stream mainly comprising hydrogen; 
   during the decompression phase, the PSA waste stream is produced;   during the purge phase, a purge gas is produced; and   where the PSA recycle gas is either the waste stream compressed to the pressure P, or the purge gas compressed to the pressure P.   
   
   
       13 . The process of  claim 8 , wherein between step a) and step b), the temperature of the gas stream comprising hydrogen and hydrocarbons is lowered to at least 0° C. 
   
   
       14 . The of  claim 8 , wherein between step a) and step b), the temperature of the gas stream comprising hydrogen and hydrocarbons is lowered by means of a cryogenic device. 
   
   
       15 . The process of  claim 9 , wherein the gas stream comprising hydrogen and hydrocarbons has a hydrogen concentration at least 10% lower relative to the value of the hydrogen concentration of the gas stream mainly comprising hydrogen. 
   
   
       16 . The process of  claim 15 , wherein the gas stream comprising hydrogen and hydrocarbons has a hydrocarbon concentration between 10 and 50 vol %. 
   
   
       17 . The process of  claim 16 , wherein the gas separation unit is a pressure swing adsorption (PSA) unit combined with an integrated compressor, in which, for each adsorber of the unit, a pressure swing cycle is carried out comprising a succession of phases which define the phases of adsorption, decompression, purge and pressure rise, such that:
 during the adsorption phase:
 during a first step, the gas stream mainly comprising hydrogen and having a pressure P is brought into contact with the bed of the adsorber; and 
 during a second step, introduced into contact with the bed of the adsorber is the mixture of pressure P whose temperature has been lowered so as to condense the hydrocarbons and that is composed of:
 on the one hand, the gas stream comprising hydrogen and hydrocarbons; and 
 on the other hand, the PSA recycle gas, 
 
  so as to adsorb the compounds other than hydrogen and to produce, at the top of the adsorber bed, the enriched stream having a hydrogen concentration greater than that of the gas stream mainly comprising hydrogen; 
   during the decompression phase, the PSA waste stream is produced;   during the purge phase, a purge gas is produced; and   where the PSA recycle gas is either the waste stream compressed to the pressure P, or the purge gas compressed to the pressure P.   
   
   
       18 . The process of  claim 17 , wherein between step a) and step b), the temperature of the gas stream comprising hydrogen and hydrocarbons is lowered to at least 0° C. 
   
   
       19 . The of  claim 18 , wherein between step a) and step b), the temperature of the gas stream comprising hydrogen and hydrocarbons is lowered by means of a cryogenic device.