Grain is delivered by truck to the ethanol plant, where it’s loaded into storage bins. Bin capacity is >1 million bushels and holds enough grain to supply the plant for 15–20 days.
The grain is screened to remove debris and then milled into flour before being introduced to the slurry process.
The ground floor is conveyed to a blender that mixes the flour with water and alpha-amylase enzymes to produce a slurry. The slurry is passed through a set of tanks where heat is introduced along with agitation to begin the process of breaking down and gelatinizing the corn starch. The alpha-amylase assists with breaking down starch into long-chain dextrins, lower viscosity and allows for higher solids slurry to be pumped through the process.
The slurry is pumped through a jet cooker mixed with steam before being passed through a pressure vessel. This process further shears the starch and kills microorganisms that are detrimental to fermentation and yeast health.
The heated slurry is pumped through 2 liquefaction tanks, giving the product additional time (2 hours) to hydrolyze the gelatinized starch into glucose dextrins and produce mash.
The mash is pumped to 1 of 5-730,000 gallon fermenters. Glucoamylase enzymes are introduced to break down the dextrins into simple sugars, glucose. Yeast is added to convert the glucose to ethanol. It takes approximately 16 hours to fill each fermenter and approximately 70 hours before the fermented product, beer, is ready to distill. The beer contains approximately 15% ethanol as well as the solids from the grain and added yeast.
The beer is pumped into a multi-column distillation system, where additional heat is added. The columns utilize the differences in ethanol and water boiling points to boil off and separate the ethanol. By the time the product stream is ready to leave the distillation columns, it contains about 95% ethanol by volume (190-proof). The residue from this process, called stillage, contains non-fermentable solids and water and is pumped out from the bottom of the columns into the centrifuges.
The 190-proof product stream is pumped into the molecular sieve system. The product is heated to over 300°F, and the resulting vapor passes through specialized tanks containing aluminosilicate beads that adsorb water molecules from the process stream while allowing ethanol molecules to pass through unaffected. When the product stream leaves the molecular sieves, it is recondensed and contains approximately 99% ethanol by volume (200 proof).
Before the ethanol is sent into commerce, a small denaturant is added, making the product unfit for human consumption.
The stillage from the bottom of the distillation columns contains solids from the grain and added yeast and liquid from the water added during the process. This stillage is then sent and separated through the centrifuges into thin stillage (a liquid with 5-10% solids) and wet distillers grain.
The liquid that is not routed back to the cook/slurry tanks is sent through a multiple-effect evaporation system, concentrated into syrup containing 25-35% solids.
We separate oil from the post-fermentation syrup stream as it leaves the evaporators. The oil is routed to oil storage tanks, and the remaining concentrated syrup is routed to both the wet distiller's grain and the syrup storage tank.