How does Chief Ethanol Fuels make ethanol?
Chief Ethanol has a 75 million gallon facility located in Hastings, Nebraska, and a 48 million gallon facility in Lexington, Nebraska. Both plants utilize the continuous flow Vogelbusch process.
The grain is run through a hammer mill which grinds it into a fine powdery meal.
The meal is combined with water and an enzyme called alpha-amylase. The mixture is heated to around 180-190 degrees Fahrenheit and is turned into a mash form.
After the mash is cooled, a second enzyme, glucoamylase, is added to convert the starch to fermentable sugars.
Yeast is introduced to the mash. As the mash passes through a series of fermentation tanks the sugars are converted to ethanol and carbon dioxide. When the mash reaches the last tank called the beer well, the fermentable sugars have been converted to alcohol.
The alcohol, water, and remaining non-fermentable solids called beer enters the distillation columns where the alcohol is separated from the solids and water mixture. The alcohol is greatly concentrated but still contains a small amount of water. The solids and water mixture now called whole stillage flows out the base of the column to centrifuges.
The separated alcohol passes through the molecular sieve dehydration system to remove the remaining water to specification. Small crystalline metal aluminosilicates beads are heated creating small cavities. The cavities are the same molecular size as water, allowing the water to be absorbed as the alcohol passes through. The product is now 200 proof and is called anhydrous ethanol.
By law, ethanol used for fuel must be unsuitable for human consumption. A small amount of gasoline (2-2.5%) is added as a denaturant to make the final denatured ethanol fuel product.
The whole stillage is sent from the distillation column to a centrifuge. This is where the heavier materials are separated and become the distillers grain. The thinner liquid is passed through an evaporator to make condensed solubles. Some of the solubles are added back into the feed. The product is now ready to be fed as a wet cake or it can be dried to further reduce the moisture. Drying increases the cost of feed but it also extends the product’s life and transportability. For more information on feed products, see the .