How is ethanol made?
Ethanol is made through a dry milling process at Nebraska Corn Processing. Most of the fuel ethanol in the U.S. is made using the dry mill method. The major steps in this process are:
The feedstock (corn) passes through a hammer mill, which grinds it into a fine powder called meal and then is conveyed into the plant.
2. Slurry and Liquefaction
The corn meal is mixed with process water and alpha-amylase forming mash and then passed through a jet cooker where the starch is liquefied and sheared. Heat is applied at this stage to reduce bacteria levels in the mash as well as allow the alpha-amylase to enable liquefaction where the starch is broken down into complex sugars.
The mash from liquefaction is cooled through plate and frame exchangers and the secondary enzyme gluco-amylase is added to convert the complex sugars into fermentable sugars (simple sugars).
Yeast is added to the mash to ferment the simple sugars into ethanol, heat and carbon dioxide. In our batch process, the mash stays in one fermenter for about 50-60 hours before the distillation process is started.
The fermented mash, now called beer, contains about 14 percent ethanol, plus all the non-fermentable solids from the corn meal and yeast cells. The mash is pumped to our continuous flow, multi-column distillation system where the ethanol is removed from the solids and the water. The ethanol leaves the top of the final column at about 190 proof, which is the azeotropic point of water and ethanol. The residual mash, called stillage, is transferred from the base of the column to the co-product processing area.
The ethanol from the top of the column passes through a dehydration system where the remaining water will be removed. Our ethanol plant uses a molecular sieve to capture the last bit of water in the ethanol. The alcohol product at this stage is called anhydrous ethanol (pure, without water) and is approximately 200 proof. The 200 proof ethanol is then pumped into storage tanks to be loaded out.
7. Ethanol Loadout.
With Blending Skids and a Distilled Spirits Permit, NCP is able to load any blend of ethanol and denaturant a customer desires into trucks or railcars, from pure ethanol to E85.
Nebraska Corn Processing produces two co-products; Wet Distillers Grain w/ Solubles (WDGS) and Feed Grade Corn Oil. We offer our WDGS with or without fat based on customer needs. Our Corn Oil is used in local feed lots as well as for biodiesel manufacturing.