Enhancing product streams from ethanol production

Abstract

Processes are described herein for realizing an enhanced yield of ethanol and co-products from the by-products (e.g., stillage) of existing ethanol production processes, particularly processes for producing ethanol from biomass containing lignocellulosic material. Also described herein are product outputs of these processes having new and useful properties and systems implementing the processes.

What is claimed is: 
     
         1 . A method for producing a sugar from lignocellulosic material in fermentation residual material, comprising:
 a. mixing an amount of an acid into the fermentation residual material;   b. agitating the fermentation residual material and the acid for a first pretreatment time at a first pretreatment temperature for a first pretreatment stage; and   c. pretreating the fermentation residual material with the acid in a pretreatment reactor for a second pretreatment time at a second pretreatment temperature for a second pretreatment stage,
 wherein the second pretreatment temperature is higher than the first pretreatment temperature and the second pretreatment pressure is higher than the first pretreatment pressure, and 
 wherein the lignocellulosic material is converted to a soluble sugar at a percent yield from about 5% to about 100% upon completion of the first pretreatment stage. 
   
     
     
         2 . The method of  claim 1 , wherein the soluble sugar includes at least one of the group consisting of glucose, xylose, mannose, arabinose, and galactose. 
     
     
         3 . The method of  claim 1 , wherein the first pretreatment temperature is from about 170° F. to about 225° F. 
     
     
         4 . The method of  claim 1 , wherein the acid is a mineral acid. 
     
     
         5 . The method of  claim 4 , wherein the mineral acid is selected from the group consisting of sulfuric acid, phosphoric acid, hydrochloric acid, hydrofluoric acid, formic acid, nitric acid, and mixtures thereof. 
     
     
         6 . The method of  claim 1 , wherein the acid is an organic acid. 
     
     
         7 . The method of  claim 6 , wherein the organic acid is selected from the group consisting of maleic acid, oxalic acid, acetic acid, fumaric acid, and mixtures thereof. 
     
     
         8 . The method of  claim 1 , wherein the amount of acid is such that the fermentation residual material has a pH of from about 1.5 to about 2.5. 
     
     
         9 . The method of  claim 1 , wherein the first pretreatment pressure is at atmospheric pressure and the first pretreatment temperature is from about 170° F. to about the boiling point of water. 
     
     
         10 . The method of  claim 1 , wherein the pretreatment reactor is selected from the group consisting of a plug flow reactor, a continuous stirred reactor and a pressurized pipe. 
     
     
         11 . The method of  claim 1 , wherein the first pretreatment time is from about 15 minutes to about 300 minutes. 
     
     
         12 . The method of  claim 1 , further comprising the step of washing the fermentation residual material to reduce a buffering capacity of the fermentation residual material before the mixing step. 
     
     
         13 . A method for hydrolyzing lignocellulosic material in fermentation residual material, comprising:
 a. feeding a fermentation residual material comprising lignocellulosic material into a recycling reactor at a feed rate;   b. adding at least one enzyme to the fermentation residual material; and   c. recycling the fermentation residual material and at least one enzyme through the recycling reactor at a recycle rate and a residence time to hydrolyze the lignocellulosic material to produce an amount of monomeric sugar in the fermentation residual material.   
     
     
         14 . The method of claim  0 , further comprising directing the fermentation residual material and at least one enzyme to a fermenter and fermenting the monomeric sugar using a microbe. 
     
     
         15 . The method of claim  0 , wherein the recycle rate is from about 1 to about 10 times the feed rate. 
     
     
         16 . The method of claim  0 , wherein the residence time is from about 6 hours to about 15 hours. 
     
     
         17 . The method of claim  0 , wherein the at least one enzyme is selected from the group consisting of cellulase, xylanase, arabinase, galactidase, mannase, amylase, and beta-glucosidase. 
     
     
         18 . A method for increasing ethanol production from lignocellulosic biomass, comprising,
 a. providing an ethanol production plant comprising a plurality of processes for producing a first ethanol stream with a byproduct of a fermentation residual material containing lignocellulosic material; and   b. adding to the ethanol production plant a cellulosic ethanol production process comprising:
 i. pretreating the fermentation residual material with an acid in two stages to hydrolyze a fraction of the lignocellulosic material into soluble sugars; 
 ii. saccharifying the fermentation residual material with an enzyme to hydrolyze a fraction of the soluble sugars into fermentable sugars; 
 iii. fermenting the fermentable sugars in the fermentation residual material to produce cellulosic ethanol; 
 iv. distilling the cellulosic ethanol from the fermentation residual material to produce a cellulosic ethanol stream and a second whole stillage, wherein the second whole stillage has a crude protein content of from about 40 wt % to about 55 wt %; and 
 v. removing water from the first ethanol stream and the cellulosic ethanol stream. 
   
     
     
         19 . A method for ethanol production with increased corn oil yield, comprising,
 a. providing an ethanol production plant comprising: distilling a first ethanol stream from fermented corn to yield a first whole stillage, and separating the first whole stillage into a first thin stillage and a corn wet cake comprising lignocellulosic material; and   b. adding to the ethanol production plant a cellulosic ethanol production process comprising:
 i. pretreating the corn wet cake with an acid in two stages to hydrolyze a first fraction of the lignocellulosic material into soluble sugars; 
 ii. saccharifying the corn wet cake with an enzyme to hydrolyze a fraction of the soluble sugars and a second fraction of the lignocellulosic material into fermentable sugar; 
 iii. fermenting the fermentable sugar in the corn wet cake to produce cellulosic ethanol; 
 iv. distilling the cellulosic ethanol from the corn wet cake to produce a cellulosic ethanol stream and a second whole stillage; 
 v. separating the second whole stillage into a second thin stillage and a low-fiber slurry; and 
 vi. evaporating the first thin stillage and the second thin stillage to produce a syrup stream and then separating distillers corn oil from the syrup stream, 
 wherein the amount of lignocellulosic material converted in the pretreating and saccharifying steps results in an increase of about 0.1 lb/bushel to 0.5 lb/bushel increase in distillers corn oil recovered. 
   
     
     
         20 . The method of claim  0 , further comprising the step of washing the corn wet cake to reduce a buffering capacity of the corn wet cake before the pretreating step.