How does CPBR make ethanol?
- Milling
- The grain is run through a hammer mill which grinds it into a fine powder meal.
- Liquefaction
- The meal is combined with water. The mixture is heated to around 180 degrees Fahrenheit and becomes a mash form.
- Saccharification
- After the mash is cooled a second enzyme 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 contains a small amount of water. The solids flow out the base of the column to the centrifuge.
- Dehydration
- The alcohol 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.
- Centrifuge
- The solids referred to as whole stillage is sent from the distillation column to a centrifuge. 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.