Method for retrofitting an existing plant with a bran fractionation process

A method for retrofitting an existing plant, the method comprising:

• adding a fractionation process to separate bran from other components in a feedstock to the existing plant, the existing plant configured to convert grain to ethanol, the existing plant including a milling process, a cook process, a fermentation process, a distillation process, a dehydration process, an evaporation process, a solid-liquid separation process, and a propagation process, the fractionation process configured to receive a mash from a slurry tank of the cook process and output a liquids stream and a solids stream, the fractionation process configured to output the liquids stream to a liquefaction tank of the cook process, wherein the adding the fractionation process further comprises adding a first mechanical separation device, the first mechanical separation device configured to receive the mash and output the liquids stream and the solids stream;
• adding a pretreatment process downstream of the fractionation process, the pretreatment process configured to receive the solids stream that is output from the fractionation process, the solids stream including the bran, the pretreatment process comprising a pretreatment slurry tank configured to utilize water and heat to break down cellulose and hemicellulose in the bran;
• adding a hydrolysis and cellulosic fermentation process downstream of the pretreatment process and upstream of the fermentation process to hydrolyze the bran with a cellulase enzyme complex cocktail and to ferment with an organism to produce cellulosic beer;
• and
• combining the cellulosic beer with starch from the grain in the existing plant into the fermentation process.