Method and installation for helium production

Abstract

The invention concerns a method which consists in cooling the feed mixture, and introducing it in the vessel of a distillation column ( 3 ), partly condensing (in 4 ) the column head gas, cooling (in 5 ) the resulting gas phase so as to condense it partly, and recuperating as impure helium the gas phase resulting from that second condensation. Additionally at least a liquid is produced through a closed refrigerating cycle ( 8 ) with variable flow-rate. The invention is useful for producing helium and liquid nitrogen from a natural gas liquefying residue gas.

1 - 14  (canceled).  
     
     
         15 . A process for producing helium from a feed gas mixture containing helium and other heavier components, comprising: 
 a) pressuring said feed mixture to a distillation pressure;    b) cooling said pressurized feed mixture;    c) introducing said feed mixture into the bottom of a distillation column;    d) partly condensing the overhead gas in the column;    e) cooling the resulting gas phase so as to partially condense it; and    f) recovering the gas phase resulting from this second partial condensation as a helium product,    wherein at least one of said components from said feed gas mixture is further processed to a liquid product by implementing a variable-rate closed refrigeration cycle, in which the rate of said refrigeration cycle depends on the output of said liquid product.    
     
     
         16 . The process of  claim 15 , wherein said refrigeration cycle is a nitrogen cycle.  
     
     
         17 . The process of  claim 15 , wherein the liquid phase obtained by the second partial condensation is enriched with one of said components and in that the resulting fluid is recovered as a second product.  
     
     
         18 . The process of  claim 17 , wherein said second product is at least partly liquid.  
     
     
         19 . The process of  claim 15 , wherein the partial condensation of said overhead gas in the column is carried out by heat exchange with pre-expanded liquid from the bottom of the column.  
     
     
         20 . The process of  claim 19 , wherein a fraction of the gas resulting from the vaporization of said expanded bottom liquid is added to the feed mixture.  
     
     
         21 . The process of  claim 20 , wherein the distillation pressure is substantially equal to the helium production pressure.  
     
     
         22 . A process for producing helium, further comprising: 
 g) sending said helium product and said liquid product to a second unit for purifying, and optionally liquefying, helium having a cryogenic part.    
     
     
         23 . A unit for producing helium from a feed gas mixture containing helium and other heavier components, comprising: 
 a) means for bringing the feed mixture to a distillation pressure;    b) a heat exchange line for cooling the feed mixture at this distillation pressure;    c) a distillation column, the bottom of which is connected to the cold end of the heat exchange line and is fitted with a top condenser;    d) a heat exchanger suitable for cooling and partly condensing the vapor phase coming from the condensation passages of the top condenser;    e) a phase separator connected to the cold end of the heat exchanger; and    f) means for recovering the vapor phase coming from the separator as a helium product,    wherein said unit further comprises a variable-rate closed refrigeration cycle for producing a variable output of a liquid product.    
     
     
         24 . The unit of  claim 23 , wherein said refrigeration cycle is a nitrogen cycle.  
     
     
         25 . The unit of  claim 23 , further comprising means for enriching the liquid phase coming from the phase separator with one of said components and means for recovering the resulting fluid as a second product.  
     
     
         26 . The unit of  claim 23 , wherein the column further comprises means for expanding its bottom liquid and for sending the expanded liquid into vaporization passages in the top condenser.  
     
     
         27 . The unit of  claim 26 , further comprising a line for recycling the gas contained in the shell of the top condenser into said feed gas mixture.  
     
     
         28 . An installation for producing pure helium comprising: 
 a) a first unit for producing helium comprising: 
 1) means for bringing the feed mixture to a distillation pressure;  
 2) a heat exchange line for cooling the feed mixture at this distillation pressure;  
 3) a distillation column, the bottom of which is connected to the cold end of the heat exchange line and is fitted with a top condenser;  
 4) a heat exchanger suitable for cooling and partly condensing the vapor phase coming from the condensation passages of the top condenser;  
 5) a phase separator connected to the cold end of the heat exchanger; and  
 6) means for recovering the vapor phase coming from the separator as a helium product,  
   wherein said unit further comprises a variable-rate closed refrigeration cycle for producing a variable output of a liquid product; and    b) a second unit for purifying, and optionally liquefying, helium having a cryogenic part, wherein said second unit is fed with the helium produced by the first unit and with said liquid product.