Methods and apparatuses for integration of a blast furnace and an air separation unit

Abstract

The present invention generally relates to processes and apparatuses for the integration of a blast furnace and an air separation plant to increase blast furnace production. The present invention recovers energy from the air separation through the expansion of a product stream.

1 . A process for integrating a blast furnace and an air separation unit comprising the steps of: 
 feeding feed air to the blast furnace;    removing a first portion of feed air to the blast furnace;    separating at least one oxygen rich stream and at least a second stream from the first portion in the air separation unit;    heating the second stream;    expanding the second stream to recover energy; and,    feeding at least a portion of the oxygen rich stream to the blast furnace.    
     
     
         2 . The process of  claim 1  wherein the oxygen rich stream is mixed with feed air prior to being fed to the blast furnace.  
     
     
         3 . The process of  claim 1  wherein at least a portion of the energy recovered is utilized to drive at least one compressor associated with the air separation unit.  
     
     
         4 . The process of  claim 1  further comprising the step of removing a low BTU off gas from the blast furnace.  
     
     
         5 . The process of  claim 1  wherein the second stream is heated by indirect heat exchange.  
     
     
         6 . The process of  claim 1  wherein the second stream is heated by a combustion product from a combustion chamber.  
     
     
         7 . The process of  claim 4  wherein the second gas is heated by a combustion product of the off gas from a combustion chamber.  
     
     
         8 . The process of  claim 1  wherein the air separation unit further comprises at least one distillation column producing an oxygen rich stream having an oxygen content greater than 21.0% by volume.  
     
     
         9 . The process of  claim 1  wherein the second stream is a nitrogen rich gas.  
     
     
         10 . The process of  claim 1  wherein the feed air is at a pressure between about three (3) bar to about ten (10) bar.  
     
     
         11 . The process of  claim 1  further comprising linking the expansion of the second gas to at least one compressor associated with the air separation unit.  
     
     
         12 . The process of  claim 1  further comprising mixing additional air with the first portion.  
     
     
         13 . A system for recovering a portion of energy associated with an air separation unit for supplying oxygen rich gas to feed air of a blast furnace comprising: 
 an air separation unit fed at least partially with a first portion of a feed air to a blast furnace from which an oxygen rich product is removed from the air separation unit and mixed with a remaining portion of the blast furnace feed air and fed to the blast furnace; removing a second gas from the air separation unit and heating the second gas; and, expanding the second gas to recover energy.    
     
     
         14 . The system of  claim 13  wherein the second gas is heated by heat exchange with a combustion product.  
     
     
         15 . The system of  claim 13  wherein the second gas is mixed with a combustion product.  
     
     
         16 . The system of  claim 13  wherein an off gas of the blast furnace is a fuel for a combustion chamber to heat the second gas.  
     
     
         17 . The system of  claim 13  further comprising mixing additional air with the first portion.