Carbon capture in fermentation

Abstract

What is described is an integrated steel mill and a bioreactor configured to produce useful products from the waste stream of the steel mill. A waste gas stack which is connected to the steel mill is connected to a heat exchanger to cool the waste gas from the steel mill. The cooled gas is pressurized using a pressurization apparatus connected to the heat exchanger. The pressurized gas is sent to an oxygen removal apparatus connected to the pressurization apparatus. An oxygen depleted waste stream from the oxygen removal apparatus is passed to a bioreactor (connected to the oxygen removal apparatus) where microorganisms ferment the waste stream to products. Optional apparatus such as scrubbers, valves, buffers, are also disclosed. The products of the fermentation in the bioreactor can be ethanol and or acetate.

1 . An apparatus comprising:
 a steel mill structure in fluid communication with at least one waste gas stack, the waste gas stack configured to remove a waste gas stream comprising CO from the steel mill structure;
 a) the at least one waste gas stack in fluid communication with a first heat exchanger, the first heat exchanger configured to receive at least a portion of the waste gas stream from the waste gas stack and reduce the temperature of the waste gas stream and produce a cooled waste gas stream; 
 b) the first heat exchanger in fluid communication with a pressurization apparatus configured to pressurize the cooled waste gas stream, producing a pressurized waste stream; 
 c) the pressurization apparatus in fluid communication with an oxygen removal apparatus configured to remove at least a portion of the oxygen in the pressurized waste stream to produce an oxygen depleted waste gas stream; 
 d) the oxygen removal apparatus in fluid communication with a fermentation system comprising at least one bioreactor, the bioreactor configured to contain a culture of at least one anaerobic bacterium wherein the anaerobic bacterium ferments at least a portion of the oxygen depleted waste gas stream to at least one product. 
   
     
     
         2 . The apparatus of  claim 1 , further comprising a valve means in fluid communication between the at least one waste gas stack and the first heat exchanger, the valve means used to control at least a portion of the waste gas stream to the first heat exchanger or to a second waste gas stack. 
     
     
         3 . The apparatus of  claim 1 , further comprising including a scrubber apparatus in fluid communication with the at least one waste gas stack and the first heat exchanger, the scrubber apparatus configured to remove at least a portion of particulate matter from the waste gas stream before passing the waste gas stream to the first heat exchanger. 
     
     
         4 . The apparatus of  claim 1 , wherein the fermentation system produces ethanol and/or acetate. 
     
     
         5 . The apparatus of  claim 1 , wherein the anaerobic bacterium is selected from  Clostridium autoethanogenum, Clostridium ljungdahlii , or  Clostridium carboxydivorans.    
     
     
         6 . The apparatus of  claim 1 , wherein the anaerobic bacterium is  Clostridium autoethanogenum.    
     
     
         7 . The apparatus of  claim 2 , further comprising a valve means in fluid communication with the scrubber apparatus and the first heat exchanger, the valve means used to control the flow of at least a portion of the waste gas stream to either the first heat exchanger or to a second waste gas stack. 
     
     
         8 . The apparatus of  claim 1 , further comprising a buffering apparatus in fluid communication with the oxygen removal apparatus and the bioreactor, the buffering apparatus configured to provide a substantially continuous waste gas stream to the bioreactor. 
     
     
         9 . The apparatus of  claim 1 , further comprising a second heat exchanger in fluid communication with the oxygen removal apparatus and a holding tube, the holding tube in fluid communication with a second valve means in fluid communication with the bioreactor and the second heat exchanger, wherein the holding tube is configured to determine the composition of the waste gas stream from the second heat exchanger and the second valve means is configured to control the flow of at least a portion of the waste stream from the holding tube either to the bioreactor or to the second waste gas stack. 
     
     
         10 . The apparatus of  claim 1 , further comprising a holding tube, the holding tube in fluid communication with the oxygen removal apparatus and with a second valve means which is in fluid communication with the bioreactor and the holding tube, wherein the holding tube is configured to determine the composition of the waste gas stream from the oxygen removal apparatus and the second valve means is configured to control the flow of at least a portion of the waste stream from the holding tube either to the bioreactor or to the second waste gas. 
     
     
         11 . The apparatus of  claim 1 , further comprising a treatment apparatus in fluid communication with the first heat exchanger and the pressurization apparatus, the pretreatment apparatus configured to remove at least a portion of residual particulate matter and/or at least a portion of condensed water. 
     
     
         12 . The apparatus of  claim 1 , where the waste gas stack is in fluid communication with a basic oxygen furnace section of the steel mill structure. 
     
     
         13 . The apparatus of  claim 1 , where the waste gas stack is in fluid communication with a coke forming section of the steel mill structure. 
     
     
         14 . The apparatus of  claim 1 , where a first waste gas stack is in fluid communication with the basic oxygen furnace section of the steel mill structure, a second waste gas stack is in fluid communication with the coke forming section of the steel mill structure and the waste streams from the first and second waste gas stacks are combined and then passed to the first heat exchanger.