Purification of inert gases to remove trace impurities

Abstract

An argon purification system is provided which includes a cryogenic heat exchanger, a cryogenic distillation column. The cryogenic heat exchanger is configured to remove heat from a pre-treated argon waste stream to create a cold feed stream. The cryogenic distillation column includes packing, a reboiler, and an overhead condenser, as well as an upper portion and a lower portion and is configured to receive a liquid feed stream and to produce a bottoms argon product stream and a gas waste stream. The reboiler is positioned in the lower portion of the cryogenic distillation column and is configured to condense the cold feed stream to produce the liquid feed stream. The condenser is positioned in the upper portion of the cryogenic distillation column and is configured to heat the bottoms argon product stream such that the bottoms argon product stream evaporates to a purified vapor phase argon stream.

What is claimed is: 
     
         1 . An argon purification system, the system comprising:
 a cryogenic heat exchanger, wherein the cryogenic heat exchanger is configured to remove heat from a pre-treated argon waste stream to create a cold feed stream;   a cryogenic distillation column comprising a packing section, a reboiler, and an overhead condenser, said cryogenic distillation column having an upper portion and a lower portion and being configured to receive a liquid feed stream and to produce a bottoms argon product stream and a gas waste stream;   wherein the reboiler is positioned in the lower portion of the cryogenic distillation column and is configured to remove heat from the cold feed stream such that the cold feed stream condenses to the liquid feed stream; and   wherein the overhead condenser is positioned in the upper portion of the cryogenic distillation column and is configured to heat the bottoms argon product stream such that the bottoms argon product stream evaporates to a purified vapor phase argon stream.   
     
     
         2 . The system as claimed in  claim 1 , wherein the cryogenic heat exchanger is further configured to heat the purified vapor phase argon stream with the heat removed from the pre-treated argon waste stream. 
     
     
         3 . The system as claimed in  claim 1 , wherein the cryogenic heat exchanger is further configured to heat the gas waste stream with the heat removed from the pre-treated argon waste stream. 
     
     
         4 . The system as claimed in  claim 1 , wherein the reboiler is configured to use the heat removed from the cold feed stream to boil the liquid in a cryogenic distillation column bottoms. 
     
     
         5 . The system as claimed in  claim 1 , wherein the overhead condenser is configured to use heat removed from a cryogenic distillation column overheads to heat the bottoms argon product stream. 
     
     
         6 . The system as claimed in  claim 1 , further comprising an expansion device in fluid communication with the bottom portion of the cryogenic distillation column, the expansion device configured to receive and expand the bottoms argon product stream before the bottoms argon product stream is fed to the overhead condenser, such that the temperature of the bottoms argon product stream is reduced. 
     
     
         7 . The system as claimed in  claim 1 , further comprising a pump that is configured to provide a driving force to get the bottoms argon product stream to the overhead condenser. 
     
     
         8 . The system as claimed in  claim 1 , further comprising an argon lift stream in fluid communication with the bottoms argon product stream, the argon lift stream configured to provide additional lift to the bottoms argon product stream by introducing gaseous argon into the bottoms argon product stream. 
     
     
         9 . The system as claimed in  claim 8 , wherein the argon lift stream is less than about 1% by mass of the bottoms argon product stream. 
     
     
         10 . The system as claimed in  claim 1 , wherein the cryogenic distillation column further comprises additional stages disposed above the overhead condenser configured to remove methane from the bottoms argon product stream. 
     
     
         11 . The system as claimed in  claim 1 , further comprising a sorbent bed system, wherein the sorbent bed system is configured to accept the bottoms argon product stream, to remove contaminants from the bottoms argon product stream to produce a sorbent bed outlet stream, and then feed the sorbent bed outlet stream to the overhead condenser. 
     
     
         12 . The system as claimed in  claim 11 , wherein the sorbent bed system is filled with regenerable adsorbents. 
     
     
         13 . The system as claimed in  claim 11 , wherein the sorbent bed system is filled with getter materials. 
     
     
         14 . The system as claimed in  claim 1 , wherein the pre-treated argon waste stream is sourced from a monocrystalline silicon production process. 
     
     
         15 . The system as claimed in  claim 1 , further comprising a recycle compressor in fluid communication with the heat exchanger, the purified vapor phase argon stream, and the cryogenic distillation column, wherein the recycle compressor is configured to compress a portion of the purified vapor phase argon stream to produce a compressed argon recycle, wherein the heat exchanger is configured to cool the compressed argon recycle before introducing the compressed argon recycle into the cryogenic distillation column for further purification.