Method for recycling argon

Abstract

A method for recycling argon from an industrial process; in which the gaseous argon is compressed after the use thereof in the industrial process, is fed to a main heat exchanger and is cooled there in contact with a first cooling medium. The compressed and cooled argon is fed to a rectification column or another cryogenic separating device and is liquefied there by direct heat exchange with a second cooling medium and is freed of low-boiling substances by rectification. The liquefied argon is drawn from the bottom of the rectification column and, after use as the first cooling medium in the main heat exchanger, is fed back into the industrial process, the raw argon being brought into thermal contact with cryogenically liquefied pure argon in the main heat exchanger and/or the rectification column. The product argon that results is highly pure and can be fed back to the industrial process.

1 . A method for reutilizing argon in an industrial process, in which argon kept in stock in the liquid state in a tank (pure argon) is taken from the tank, vaporized and fed in gaseous form to an industrial process, wherein:
 a. the gaseous argon which has been used in the industrial process (crude argon) is compressed in a compressor;   b. the compressed crude argon is fed to a main heat exchanger and cooled there by indirect heat exchange with at least one first cooling medium;   c. the compressed and cooled crude argon is fed to a separation device and cooled there by heat exchange with a second cooling medium to a temperature below the boiling point of argon at the pressure prevailing in the separation device, resulting in a gas phase composed of argon contaminated with low boilers and a liquid phase composed of argon which has been at least largely freed of low boilers (product argon) being formed;   d. the gas phase is at least partly taken off from a head space of the separation device;   e. the product argon is taken off in the liquid state from a bottom region of the separation device, depressurized and used in the main heat exchanger as cooling medium for cooling the crude argon, resulting in it vaporizing;   f. the vaporized product argon is at least partly recirculated to the industrial process;   g. where liquid pure argon is taken from the tank and brought into direct or indirect thermal contact with the crude argon in order to cool the crude argon in the separation device and/or during feeding of the crude argon to the separation device.   
     
     
         2 . The method as claimed in  claim 1 , wherein the separation device is a rectification column or a condenser. 
     
     
         3 . The method as claimed in  claim 1 , wherein the pure argon taken from the tank is fed into the head space of the separation device. 
     
     
         4 . The method as claimed in  claim 1 , wherein argon enriched with low boilers is at least partly taken off from the head space of the separation device, fed to an overhead condenser, cooled there by indirect heat exchange with a third cooling medium and subsequently fed back into the separation device, with pure argon taken off from the tank and/or depressurized product argon being used as third cooling medium in the overhead condenser. 
     
     
         5 . The method as claimed in  claim 1 , wherein pure argon taken off from the tank is used as cooling medium in the main heat exchanger. 
     
     
         6 . The method as claimed in  claim 3 , wherein the pure argon which has been used as cooling medium in the overhead condenser and/or the main heat exchanger is fed to the industrial process. 
     
     
         7 . The method as claimed in  claim 1 , wherein the product argon is fed to a device for separating off relatively high-boiling constituents before it is recirculated to the industrial process. 
     
     
         8 . The method as claimed in  claim 4 , wherein the pure argon which has been used as cooling medium in the overhead condenser and/or the main heat exchanger is fed to the industrial process.