Methods for recovering argon

Abstract

Methods for recovering argon from a natural gas stream being purified are disclosed. The argon will be separated from the natural gas with helium and other impurities and can be recovered as liquids from the flash separation step of purifying the helium. The argon that is separated from the helium can be rectified to remove further impurities from the argon which can be recovered for storage or other uses.

1 . A method for recovering argon from a natural gas stream comprising the steps:
 a) directing a natural gas stream containing natural gas, hydrocarbons, crude helium and argon to a helium recovery unit;   b) separating a gas stream containing helium and argon from said natural gas stream and directing said helium and argon to a helium purifier;   c) purifying said helium; and   d) recovering argon from said purified helium.   
   
   
       2 . The method as claimed in  claim 1  wherein said helium recovery unit is a cryogenic rectifier. 
   
   
       3 . The method as claimed in  claim 2  wherein argon is present in an amount ranging from 10 ppm to about 10000 ppm. 
   
   
       4 . The method as claimed in  claim 1  wherein said purified helium is directed to a helium liquefier or storage. 
   
   
       5 . The method as claimed in  claim 1  wherein said argon is recovered by rectification. 
   
   
       6 . The method as claimed in  claim 5  wherein said rectification is selected from the group consisting of cryogenic rectification and selective adsorption. 
   
   
       7 . A method for recovering argon from a natural gas stream comprising the steps;
 a) separating crude helium and argon from said natural gas stream;   b) directing said separated gas stream to a first helium separation unit, wherein argon is separated from said gas stream and directed to an argon concentration unit;   c) directing said helium from said first helium separation unit to an enriched helium separation unit;   d) concentrating argon by removing nitrogen from said argon concentration unit; and   e) recovering concentrated argon from said argon concentration unit.   
   
   
       8 . The method as claimed in  claim 7  wherein said helium recovery unit is a cryogenic rectifier. 
   
   
       9 . The method as claimed in  claim 8  wherein argon is present in an amount ranging from 10 ppm to about 10000 ppm. 
   
   
       10 . The method as claimed in  claim 7  wherein said helium is withdrawn from said enriched helium separation unit and directed to a helium liquefier or storage. 
   
   
       11 . The method as claimed in  claim 7  wherein said argon concentration unit is a rectification unit. 
   
   
       12 . The method as claimed in  claim 11  wherein said rectification unit is a cryogenic rectification unit. 
   
   
       13 . The method as claimed in  claim 11  wherein said argon concentration unit is an adsorptive separation unit. 
   
   
       14 . A method for recovering argon during the purification of a helium gas stream mixture separated from a natural gas stream comprising recovering the liquid bottoms from the purification of said helium and subjecting said liquid bottoms to a rectification process to recover argon. 
   
   
       15 . The method as claimed in  claim 14  wherein said purification of helium is performed in a helium recovery unit. 
   
   
       16 . The method as claimed in  claim 14  wherein said helium recovery unit is a cryogenic rectifier. 
   
   
       17 . The method as claimed in  claim 16  wherein argon is present in an amount ranging from 10 ppm to about 10000 ppm. 
   
   
       18 . The method as claimed in  claim 14  wherein said liquid bottoms contain argon and nitrogen. 
   
   
       19 . The method as claimed in  claim 5  wherein said rectification is selected from the group consisting of cryogenic rectification and selective adsorption.