Process and system for producing ethanol from a byproduct of an ethanol production facility

Abstract

A process of producing ethanol from whole stillage, includes obtaining a supply of whole stillage from an ethanol production facility after ethanol has been extracted therefrom; pre-treating the whole stillage to convert hemicellulose portions of the whole stillage into sugars; adding enzymes to the whole stillage to convert cellulose portions of the whole stillage to sugars; fermenting the whole stillage to create a beer mixture; and distilling the beer mixture to separate ethanol therefrom. The pre-treating step may include adding acid to the whole stillage to decrease its pH level; heating and pressurizing the whole stillage; holding the whole stillage under pressure and heat for a dwell time; removing pressure from the whole stillage to cause flashing; and cooling the whole stillage before the enzymes are added.

1 . A process of producing ethanol from whole stillage, the process comprising:
 obtaining a supply of whole stillage from an ethanol production facility;   pre-treating the whole stillage to convert hemicellulose portions of the whole stillage into sugars, the pre-treating step comprising:
 adding acid to the whole stillage to decrease its pH level; 
 heating and pressurizing the whole stillage; 
 holding the whole stillage under pressure and heat for a dwell time; 
 removing pressure from the whole stillage to cause flashing; 
 cooling the whole stillage; 
   adding enzymes to the whole stillage to convert cellulose portions of the whole stillage into sugars;   fermenting the whole stillage to create a beer mixture;   distilling the beer mixture to separate ethanol therefrom;   transferring the ethanol from the distilling step to the ethanol production facility to be combined with ethanol produced by the ethanol production facility.   
     
     
         2 . The process of  claim 1 , wherein the heating and pressurizing step heats the whole stillage to approximately 200° F.-300° F. and pressurizes the mixture to above a vapor pressure of the mixture. 
     
     
         3 . The process of  claim 1 , wherein the dwell time is approximately 1-20 minutes. 
     
     
         4 . The process of  claim 1 , wherein the adding enzymes step and fermenting step are performed in a single vessel or separate vessels.