How does Chief Ethanol Fuels make ethanol?
Chief Ethanol Fuels, Inc, expects to be producing around 120 million gallons of ethanol in the coming year between its two facilities.
Both plants utilize the continuous flow Vogelbusch process.
Milling – The grain is run through a hammer mill which grinds it into a fine powdery meal.
Liquefaction – The meal is combined with water and an enzyme called alpha-amylase. The mixture is heated to around 180 degrees Fahrenheit and is now in a mash form.
Saccharification – After the mash is cooled a second enzyme gluco amylase is added to convert the starch to fermentable sugars.
Fermentation – Yeast is introduced to the mash. As the mash passes through a series of fermentation tanks the sugars are converted to ethanol. When the mash reaches the last tank called the beer well, all fermentable sugars have been converted to alcohol.
Distillation – The alcohol and remaining non-fermentable solids enters the distillation columns where the alcohol is separated from the solids. The alcohol is greatly concentrated but still contains a small amount of water. The solids flow out the base of the column to the centrifuge.
Dehydration – The alcohol now passes through the molecular sieve dehydration system. 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. Gasoline is added as a denaturant.
Centrifuge – The solids referred to as 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 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 co-products page.