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Methods and systems for producing fermentation products from carbohydrate-rich substrates

  • US 9,428,772 B2
  • Filed: 10/27/2015
  • Issued: 08/30/2016
  • Est. Priority Date: 02/02/2014
  • Status: Active Grant
First Claim
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1. A process for producing a fermentation product from a carbohydrate-rich substrate, said process comprising the steps of:

  • (a) providing a carbohydrate-rich substrate and an aqueous solution containing a hydrolysis catalyst and a fermentation organism, and maintaining a gas pressure above said carbohydrate-rich substrate at an evacuation pressure and for an evacuation time to infuse said aqueous solution into said carbohydrate-rich substrate at an infusion temperature, thereby generating a reaction mixture;

    (b) exposing said reaction mixture to a gas-phase reaction pressure that is higher than said evacuation pressure;

    (c) maintaining said reaction mixture at a reaction temperature for a reaction time to generate sugar monomers within lumen space of said carbohydrate-rich substrate;

    (d) exposing said reaction mixture to a gas-phase expulsion pressure that is lower than said reaction pressure, to pump said sugar monomers out of said lumen space and into said aqueous solution;

    (e) maintaining said reaction mixture at an expulsion temperature for an expulsion time;

    (f) repeating steps (b) to (e) for at least two pressure cycles to remove, by a pumping mechanism, said sugar monomers from said lumen space;

    (g) fermenting at least a portion of said sugar monomers with said fermentation organism to generate a fermentation product in said aqueous solution; and

    (h) recovering said fermentation product from said aqueous solution,wherein said process does not include steam explosion or ammonia fiber expansion of said carbohydrate-rich substrate.

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