Alcohol Production Process
The alcohol production process from sugar beet has the following steps:
- Harvesting, transportation and storage of stalks and grains, Sugar beet roots are mechanically harvested and transported to the plant. Maximum storage period allowed (after harvesting is three days). Thus storage space is designed for three days storage of beet roots in open yards in piles.
- Juice extraction operations : Beet roots are washed with water to remove dirt, sand, etc before the next stage of processing. The washed beet roots are then shredded at the knife station. Shreds are fed to the extractive hydrolysis section, where hot water is passed counter currently to extract sugar in the form of juice. Extracted juice usually contains 12-13% w/w sugars. PRAJ has developed a news patented process of extractive Hydrolysis as on option to conventional Diffusion. This process normally give higher sugar than those achieved by diffusion, thus resulting in higher ethanol yields making the process more viable.
- Juice concentration: Dilute juice extracted from the extractive hydrolysis process is evaporated in multi stage evaporation unit to convert it to concentrated juice form. This concentrated juice is then fermented to produce ethanol. Excess concentrated juice is stored for plant operation during off-season.
- Fermentation : The concentrated juice produced from beet root juice is diluted by effluent recycle and process water. This is then fermented for producing alcohol in a continuous fermentation plant. This generates a mash with 9 to 11% v/v alcohol-concentration.
- Distillation and dehydration : The fermented mash is subjected to distillation where alcohol is separated and concentrated by the distillation plant and further dehydrated to 99.6 % v/v strength by molecular sieve technology.
- Solid liquid separation : Solid pulp of sugar beet, after juice extraction is further squeezed in a decanter or screw press to separate juice from it. Finally, the pulps dried and disposed as animal feed or fuel for the boiler furnace.
- Effluent Treatment : Spent wash generated from the distillation plant is decanted to remove any suspended material like pulp fibers present in spent wash and mixed with pulp. Around 70% of the decanted spent wash is recycled back to the fermentation unit. The balance 30% of decanted spent wash is aerated for the reduction of BOD/COD level. Aerated spent a\wash is used for ferti-irrigation.
- Characteristics of Sugar Beet effluent is enclosed.