Ethanol Process Overview
How is Ethanol made? Below you will be giving a very
simple flow of the Ethanol production process from a grain raw material
product to the finished products.
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Grain / Milling
The raw product being processed (wheat / corn are the most predominate
crops for ethanol plants in Canada), is received by truck and placed
into storage bins. These bins feed a roller or hammer mill which process
the grain to give more surface area to the product.
Mashing / Liquefaction
In this process a series of tanks are utilized to mix the dry grain (now
referred to as “meal”) with water and specific enzymes. The product is
also heated and agitated. During this process the grain cells begin
gelatinization. During this stage of the process the starch cells are
being broken down into glucose.
Fermentation
Fermentation is the “heart of the plant”. During the fermentation
process typically yeast is used to convert sugar to ethyl alcohol. The
conversion process can take from 40 to 60 hours to complete.
Disillation
The distillation process normally consists of a column (also called a
“train”) which is filled with water and ethanol with a steam source from
the bottom. While the column is heated ethanol is extracted from the top
and soiled water flows from the bottom.
The ethanol extracted from the top are processed further by equipment in
the distillation room. Soiled water extracted from the bottom flows to
the Whole Stillage tank.
Ethanol Storage
Once the ethanol has been fully processed and the product is verified to
meet the specifications it is pumped to the ethanol storage tank.
Whole Stillage
The soiled water from the bottom for the still is collected in this
tank. This liquid will have suspended solids which can be extracted to
make cattle feed.
Centrifuge
Whole stillage is pumped to the centrifuge which spins at a high RPM.
The centrifuge separates the solids from liquids. Liquids are pumped to
a storage tank called Thin Stillage and solids are used to make Wet
Distiller Grain (WDG), Dry Distiller Grain (DDG) or at times both at
once by splitting the solids feed.
Wet Distiller Grain (WDG)
Solids from the centrifuge are mixed with syrup to produce the final
product
Dryer
Solids from the centrifuge are cooked in the drying unit which produces
the final product referred to as Dry Distiller Grain (DDG).
Thin Stillage
Thin Stillage still contains minute amounts of solids which can be
extracted. In order to extract these solids the product is ran through
an evaporator system.
Evaporator System
Using a combination of heat and vacuum moisture is evaporated leaving a
syrup texture liquid.
Syrup
Syrup is used in three ways:
1. As an additive to WDG
2. As an additive to DDG
3. Sold directly to customers
These are the basic steps in most Ethanol production
plants. Many variations throughout the process exist but the
fundamentals are very similar.
