| Ethanol Production Process |
Description of Dry Mill Process
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Receiving and Storage
The majority of corn arrives at the site via rail car delivered by Wisconsin and Southern Railroad approximately three times per week. Nearby corn arrives by truck. Automated unloading systems can be self-operated by the truck driver and the rail cars are typically unloaded during low truck traffic times.
A fifteen thousand bushel per hour grain system screens the corn for rocks and cobs before being sent to one of two 225,000-bushel storage bins. To begin processing, the corn is transferred to a "day bin" and metered to the hammermill by a computer-controlled weigh belt feeder, then ground and pneumatically conveyed to the slurry tank for enzymatic processing.
Cooking, Liquefaction, Saccharification and Fermentation
The addition of water, heat and enzymes break the ground corn into fine slurry. The slurry is heated for sterilization and is pumped to a Liquefaction tank where other enzymes are added to convert the starches into glucose sugars. Next the corn slurry is pumped into one of three fermenters where yeast is added to begin the forty-eight to fifty hour batch fermentation process.
Distillation
ICM's process utilizes a vacuum distillation system to divide the alcohol from the corn mash. Both streams are routed to the dehydration equipment. 145 proof alcohol exiting the distillation stripper then exits the rectifier at 190 proof and is dried to 200 proof in an ICM designed molecular sieve.
Solids Separation and Evaporation
Mash streams from the distillation stripper are pumped to one of several decanter type centrifuges for dewatering. The water, "thin stillage" is pumped to a steam driven evaporator to produce a thick syrup. The solids stream exiting the centrifuge, "wet cake" are conveyed to the DDG dryer.
Distillers Grains Drying
Syrup from the evaporator and wet cake from the centrifuge are conveyed to the DDGS natural gas fired rotary dryer. This unit removes moisture and produces the golden dried distillers grains with solubles (DDGS). Multiple passes produces a ten percent moisture product (DDGS) and one pass drying produces a fifty percent moisture product (DWG). BSE will have the capability to produce either product on a daily basis.
The ten percent DDGS is pneumatically conveyed to flat storage to cool and readied for shipment via jumbo rail car or hopper bottom trucks. Fifty percent moisture DWG is shipped locally via "moving floor" trucks.
Ethanol Storage
There are two, seven hundred fifty thousand gallon denatured ethanol storage tanks on site. The tanks were built to code and utilize the covered top floating roof design which incorporates the appropriate relief valves. Additional smaller tanks were erected for denaturant storage and temporary storage. There are truck and railcar load-out facilities.
Carbon Dioxide
The fermenter produces carbon dioxide gas that can be processed into salable product. ICM's design will collect the gases and remove impurities with a packed water scrubber. Additional transfer fans will need to be added pending the specifications of the future CO2 vendor. At this time BSE plans to look at CO2 recovery as a future venture.
Principal Products and Their Markets
The principal products produced at our ethanol plant are ethanol and distiller grains.
Ethanol
Ethanol is ethyl alcohol, a fuel component made primarily from corn and various other grains, and can be used as:
- An octane enhancer in fuels;
- An oxygenated fuel additive that can reduce carbon monoxide vehicle emissions; and
- A non-petroleum-based gasoline extender.
Most ethanol is used in its primary form for blending with unleaded gasoline and other fuel products.
The implementation of the Federal Clean Air act has made ethanol fuels an important domestic renewable fuel additive. Used as a fuel oxygenate, ethanol provides a means to reduce carbon monoxide vehicle emissions. The principal purchasers of ethanol are generally the wholesale gasoline marketer or blender. We expect that the principle markets for our ethanol will be petroleum terminals in the Wisconsin, Illinois and upper Midwest area.
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