Method and device for treating a carbon dioxide-containing gas stream

Abstract

The invention relates to a method and an apparatus for treating a carbon dioxide-containing gas stream. Precompressed raw gas stream ( 1 ) is partially liquefied in a cryogenic carbon dioxide purification stage ( 2, 3, 4 ). Part of the resultant liquid is used to obtain a gas stream having an elevated carbon dioxide content ( 7 ). From the non-liquefied raw gas, a gas stream having a reduced carbon dioxide content is obtained. This vent gas stream is expanded and the refrigeration generated is recovered for cooling the raw gas stream. The carbon dioxide gas stream is compressed ( 8 ) to a final pressure and fed to further utilization and/or storage. Another part of the liquid from the cryogenic carbon dioxide purification stage is fed in a liquid phase ( 9 ) to further utilization and/or storage ( 10 ).

1 . A method for treating a carbon dioxide-containing gas stream comprising:
 partially liquefying precompressed raw carbon dioxide-containing gas stream in a cryogenic carbon dioxide purification stage,   removing from said cryogenic carbon dioxide purification stage a liquid stream having an elevated carbon dioxide content and a gas stream having a reduced carbon dioxide content,   reevaporating a first portion of the liquid stream having an elevated carbon dioxide content to obtain a gas stream having an elevated carbon dioxide content,   expanding the gas stream having a reduced carbon dioxide content in at least one expansion turbine and recovering the resultant refrigeration generated in this expansion for cooling the precompressed raw carbon dioxide-containing gas stream,   compressing the gas stream having an elevated carbon dioxide content to a final pressure, and   feeding the resultant compressed gas stream having an elevated carbon dioxide content to further utilization and/or storage,   wherein a second portion of the liquid stream having an elevated carbon dioxide content removed from said cryogenic carbon dioxide purification stage is fed in a liquid phase to further utilization and/or storage.   
     
     
         2 . The method according to  claim 1 , wherein said precompressed raw carbon dioxide-containing gas stream is a raw gas stream form a large-scale furnace plant. 
     
     
         3 . The method according to  claim 1 , wherein the second portion of the liquid stream having an elevated carbon dioxide content is 5 to 25% of the total liquid removed from the cryogenic carbon dioxide purification stage. 
     
     
         4 . The method according to  claim 3 , wherein the second portion of the liquid stream having an elevated carbon dioxide content is 10 to 15% of the total liquid removed from the cryogenic carbon dioxide purification stage. 
     
     
         5 . The method according to  claim 1 , wherein the second portion of the liquid stream having an elevated carbon dioxide content is introduced into the gas stream having an elevated carbon dioxide content after compression of the second portion of the liquid stream having an elevated carbon dioxide content to the final pressure. 
     
     
         6 . The method according to  claim 5 , wherein the second portion of the liquid stream is compressed to the final pressure by way of a liquid pump before it is introduced into the gas stream having an elevated carbon dioxide content. 
     
     
         7 . The method according to  claim 1 , wherein said second portion of the liquid stream having an elevated carbon dioxide content is temporarily stored in a liquid gas tank for further use. 
     
     
         8 . The method according to  claim 3 , said second portion of the liquid stream having an elevated carbon dioxide content is used as transport medium for the pneumatic transport of feedstocks. 
     
     
         9 . An apparatus for treating a carbon dioxide-containing gas stream, said apparatus comprising:
 a carbon dioxide purification appliance comprising an inlet for introducing a precompressed raw carbon dioxide-containing gas stream, an outlet line for removal of a gas stream having an elevated carbon dioxide content and another outlet line for removal of a gas stream having a reduced carbon dioxide content,   said outlet line for removal of a gas stream having an elevated carbon dioxide content being connected via a final compressor to a utilization appliance and/or repository,   said another outlet line for removal of a gas stream having a reduced carbon dioxide content being connected to at least one expansion turbine comprising an outlet line for removal of at least partially expanded gas stream having a reduced carbon dioxide content which is connected to an inlet of a heat-exchange appliance, and said heat exchange appliance further having inlets for introduction of said precompressed raw gas stream and said gas stream having an elevated carbon dioxide content,   wherein said carbon dioxide purification appliance additionally comprises an outlet line for a liquid stream having an elevated carbon dioxide content, which bypasses said heat-exchange appliance and said final compressor, and is connected directly to a utilization appliance and/or storage appliance for liquid having an elevated carbon dioxide content.   
     
     
         10 . The apparatus according to  claim 9 , wherein said outlet line for a liquid stream having an elevated carbon dioxide content comprises a liquid pump and, downstream of said final compressor, outlet line for a liquid stream having an elevated carbon dioxide content communicates with said the outlet line for removal of a gas stream having an elevated carbon dioxide content being.