Production of helium from a gas stream containing hydrogen

Abstract

The invention relates to a method for producing helium from a source gas stream ( 1 ) including at least helium, methane, nitrogen and hydrogen, comprising at least the following consecutive steps: step a): injecting said source gas stream ( 1 ) into at least one compressor ( 3 ); step b): eliminating the hydrogen and the methane by reacting the stream ( 4 ) obtained from step a) with oxygen; step c): eliminating at least the impurities from step b) by temperature swing adsorption (TSA); step d): partially condensing the stream ( 8 ) obtained from step c) in order to produce a stream ( 10 ) of liquid nitrogen and a gas stream ( 11 ) comprising mostly helium; step e): purifying the gas stream ( 11 ) obtained from step d) in order to increase the helium content by pressure swing adsorption (PSA) by eliminating the nitrogen and the impurities contained in the gas stream ( 11 ) obtained from step d).

1 . A process for producing helium from a source gas stream ( 1 ) comprising at least helium, methane, nitrogen and hydrogen, the process comprising at least the following successive steps:
 step a): introducing said source gas stream ( 1 ) into at least one compressor ( 3 );   step b): removing hydrogen and methane by reaction of the stream ( 4 ) obtained from step a) with oxygen;   step c): removing at least the impurities obtained from step b) by temperature swing adsorption (TSA);   step d): partially condensing the stream ( 8 ) obtained from step c) so as to produce a liquid nitrogen stream ( 10 ) and a gas stream ( 11 ) predominantly comprising helium;   step e): purifying the gas stream ( 11 ) obtained from step d) so as to increase the helium content by pressure swing adsorption (PSA) by removing the nitrogen and the impurities contained in the gas stream ( 11 ) obtained from step d).   
     
     
         2 . The process of  claim 1 , wherein the source gas stream ( 1 ) comprises from 40% to 95% by volume of nitrogen, from 0.05% to 40% by volume of helium, from 50 ppmv to 5% by volume of methane and from 1% to 10% by volume of hydrogen. 
     
     
         3 . The process as claimed in  claim 2 , characterized in that the source gas stream ( 1 ) comprises from 40% to 60% by volume of nitrogen, from 30% to 50% by volume of helium, from 50 ppmv to 5% by volume of methane and from 1% to 10% by volume of hydrogen. 
     
     
         4 . The process of  claim 1  further comprising a step prior to step a) of producing the source gas stream ( 1 ) to be treated by means of a nitrogen rejection unit ( 2 ) or a natural gas liquefaction unit, said nitrogen rejection unit ( 2 ) or natural gas liquefaction unit producing a liquid nitrogen stream ( 20 ) used in step d) to partially condense the stream ( 8 ) obtained from step c). 
     
     
         5 . The process of  claim 1 , wherein the pressure of the source gas stream ( 1 ) on conclusion of step a) is between 15 bara and 35 bara. 
     
     
         6 . The process of  claim 1 , wherein the gas stream ( 6 ) obtained from step b) comprises less than 1 ppm by volume of hydrogen and less than 1 ppm by volume of methane. 
     
     
         7 . The process of  claim 1 , wherein said impurities contained in the gas stream ( 6 ) obtained from step b) predominantly comprise carbon dioxide and water. 
     
     
         8 . The process of  claim 1 , wherein the liquid nitrogen stream obtained from step d) comprises more than 98.5% by volume of nitrogen. 
     
     
         9 . The process of  claim 1 , wherein said gas stream obtained from step d) comprises between 80% by volume and 95% by volume of helium. 
     
     
         10 . The process of  claim 1 , wherein said gas stream obtained from step e) comprises at least 99.9% by volume of helium. 
     
     
         11 . The process of  claim 1 , wherein in step b) the gas stream obtained from step a) is placed in contact with oxygen and a catalytic bed comprising particles of at least one metal chosen from copper, platinum, palladium, osmium, iridium, ruthenium and rhodium, wherein the metal is supported on a support that is chemically inert with respect to carbon dioxide and water, and wherein to the catalyst bed catalyzes a reaction of the methane and hydrogen with oxygen. 
     
     
         12 . The process of  claim 1 , further comprising an additional step f) of liquefaction of the helium obtained from step e). 
     
     
         13 . The process of  claim 1 , wherein in the liquid nitrogen obtained from step d) cools the helium liquefied in step f). 
     
     
         14 . An installation for producing helium from a source gas mixture ( 1 ) comprising methane, helium, hydrogen and nitrogen, comprising at least one compressor ( 3 ) directly receiving the source gas mixture ( 1 ), at least system ( 5 ) for removing hydrogen and methane, at least one nitrogen-removing and helium-concentrating device ( 9 ), and at least one helium purification system ( 13 ) located downstream of the nitrogen-removing and helium-concentrating device ( 9 ), wherein the system ( 5 ) for removing hydrogen and methane is located downstream of said at least one compressor ( 3 ) and upstream of the nitrogen-removing and helium-concentrating device ( 9 ). 
     
     
         15 . The installation of  claim 14 , further comprising a helium liquefaction device ( 17 ) downstream of the helium purification means ( 13 ).