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| INDUSTRIES SERVED :
ALCOHOL |
Alcohol processes such as Ethanol and Methanol processes have recently been recognized as a prime candidate for DCS based advanced controls. From extensive studies, we have been able to recognize the true relationships between the variables and we are now able to provide powerful and robust advanced controls solutions.
The industry has so far not benefited from advanced controls. This is typical of small units or processes where it is estimated that implementation of MPC or Neural Network technologies will be too costly to implement. This fits in with our proprietary DCS based advanced controls schemes which are geared towards processes that do not have too much multivariable interactions. Of course when the need calls for MPC technology, we will certainly be glad to provide that solution also. |
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We are presently developing packaged solutions for alcohol plants as we have done for Polyethylene and polypropylene plants. |
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| For the Ethanol Process, we provide PID tuning, controls and optimization for the following areas: |
Hot Slurry
The milled grain is mixed with process water, the pH is adjusted to about 5.8, and an alpha-amylase enzyme is added. The slurry is heated to 180–190°F for 30–45 minutes to reduce viscosity. |
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Primary Liquefaction
The slurry is then pumped through a pressurized jet cooker at 221°F and held for 5 minutes. The mixture is then cooled by an atmospheric or vacuum flash condenser. |
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Secondary Liquefaction
After the flash condensation cooling, the mixture is held for 1–2 hours at 180–190°F to give the alpha-amylase enzyme time to break down the starch into short chain dextrins.After pH and temperature adjustment, a second enzyme, glucoamylase, is added as the mixture is pumped into the fermentation tanks. |
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Simultaneous Saccharification Fermentation
Once inside the fermentation tanks, the mixture is referred to as mash. The glucoamylase enzyme breaks down the dextrins to form simple sugars. Yeast is added to convert the sugar to ethanol and carbon dioxide. The mash is then allowed to ferment for 50–60 hours, resulting in a mixture that contains about 15% ethanol as well as the solids from the grain and added yeast. |
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Distillation
The fermented mash is pumped into a multi-column distillation system where additional heat is added. The columns utilize the differences in the boiling points of ethanol and water 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. |
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Dehydration
The 190-proof ethanol still contains about 5% water. It’s passed through a molecular sieve to physically separate the remaining water from the ethanol based on the different sizes of the molecules. This step produces 200-proof anhydrous (waterless) ethanol.. |
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Co-Product Processing
During the ethanol production process, two valuable co-products are created: carbon dioxide and distillers grains.
As yeast ferment the sugar, they release large amounts of carbon dioxide gas. It can be released into the atmosphere, but it’s commonly captured and purified with a scrubber so it can be marketed to the food processing industry for use in carbonated beverages and flash-freezing applications.
The stillage from the bottom of the distillation tanks contains solids from the grain and added yeast as well as liquid from the water added during the process. It’s sent to centrifuges for separation into thin stillage (a liquid with 5–10% solids) and wet distillers grain.
Some of the thin stillage is routed back to the cook/slurry tanks as makeup water, reducing the amount of fresh water required by the cook process. The rest is sent through a multiple-effect evaporation system where it is concentrated into syrup containing 25–50% solids. This syrup, which is high in protein and fat content, is then mixed back in with the wet distillers grain (WDG). |
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| Drying System |
