Ethanol is a colourless volatile flammable liquid C2H5OH that is the intoxicating agent in liquors and is also used as a solvent called ethyl alcohol or grain alcohol (Meriam 1). C2H5OH is the chemical components of ethanol; this means ethanol is made of Carbon, Hydrogen, and Hydroxide. Starch or sugar-based feedstock, such as corn, have been used to produce ethanol and ethyl alcohol since the beginning ventures into value-added processing (How Ethanol 1). The value-added process means the value is added to producing corn because we now have more valuable uses for the grain. Since natural resources are limited, ethanol provides us with an alternate fuel source. The basic steps to produce ethanol have been refined in the past years, which has lead to a highly efficient process (How Ethanol 1). This analysis explains the steps in producing ethanol from corn.
The steps for producing ethanol are steeping the corn, which involves grinding and/or soaking, and then cooking, fermenting, and distilling the corn. Dry and Wet Milling is the two different ways ethanol can be produced (How Ethanol 1). The initial grain treatment is the major difference between these two processes (How Ethanol 1). In the Dry Mill process, the corn is put through a grinder, cookers, fermenter, distillation columns, and a molecular sieve. In the Wet Mill process, the corn is steeped, put through a starch/gluten separator, and then the starch is fermented, (refer to the image for dry milling process).
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Dry Mill Ethanol Production
According to the RFA, grinding the complete corn kernel or other starchy grain produces flour, also known as a meal. The meal is then processed without separating the different component parts of the grain. Water is mixed with the meal to form a mash to which enzymes are added to convert the mash starch into sugar. Ammonia is also combined with the mash to activate the yeast and control pH balance.
The mash is then put in a high-temperature cooker to help keep the bacteria level low before fermentation. The mash is cooled and moved to the fermenters where the addition of yeast produces ethanol and carbon dioxide from the sugar.
During the forty or fifty-hour fermentation process, the mash is agitated and kept cool to help the yeast activation. The mash is then transferred to distillation columns where the ethanol is separated from the remaining mash. Conventional distillation methods produce 190 proof ethanol and then dehydration in a molecular sieve produces 200 proof ethanol. With the addition of five per cent gasoline, the ethanol is ready to be shipped to gasoline terminals or retailers.
Wet Mill Ethanol Production
The Wet Milling process starts with soaking the grain in water and sulfurous acid mix for 24 to 48 hours. This steeping process helps break the grain down.
This mix is then ground to separate the corn germ. Centrifugal, screen, and hydrochloric separators then separate the remaining fibre, gluten and starch.
An evaporator concentrates the steeping liquor. The liquor is dried so the heavy steep water and gluten component can be separated from the starch and water mix. The starch and water mix is then fermented into ethanol much like the dry mill process.
The starch is put in the fermenter with yeast where the sugar is converted to ethanol and carbon dioxide. The ethanol is separated and concentrated to 200 proof using conventional distillation and the molecular sieve system. Five per cent of gasoline is then added to the ethanol. This prepares it for the market. (How Ethanol 1)
Ethanol can reduce tailpipe emissions and still maintain engine performance. It can also boost our economy by importing less and providing farmers with business. Dry and wet milling is the two ways ethanol can be produced. The dry milling process requires the grain to be ground, cooked, fermented and distilled. The wet milling process requires the grain to be steeped, separated, fermented, and distilled. The production of ethanol would cause many improvements to our country.
“Merriam-Webster’s Collegiate Dictionary.” 2001. Britannica. 30 Oct. 01.
“How Ethanol is Made.” 2000. RFA. 30 Oct. 01. http://www.ethanolrfa.org/prod_process.html
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