Ethanol yield calculation from sucrose and its process intermediates
This paper explained the calculation of ethanol yield from various raw materials (intermediates) in the sugar production process, such as cane juice, secondary juice, syrup, A-molasses, B-heavy molasses and final molasses.
Calculation of the theoretical yield of ethanol from sucrose
The chemical equation from sucrose to ethanol can be written as (stoichiometric equation)
Sucrose Glucose + Fructose Ethanol (ethyl alcohol)
The molecular weight of sucrose is 342.30 gm/mol or kg/kmol
100% Sucrose 53.84% Ethanol + 51.43% Carbon Dioxide
Calculation of theoretical ethanol yield from glucose/fructose (reducing sugars)
The chemical equation from reducing sugar to ethanol can be written as (stoichiometric equation)
Glucose/fructose Ethanol (ethyl alcohol)
Molecular weight glucose/fractose – 180.16 g/mol or kg/kmol
Molecular weight glucose/fractose – 180.16 g/mol or kg/kmol
The molecular weight of ethyl alcohol is 46.07 g/mol or kg/kmol
The molecular weight of ethyl alcohol is 46.07 g/mol or kg/kmol
The molecular weight of carbon dioxide is 44.01 gm/mol or kg/kmol
The molecular weight of carbon dioxide is 44.01 gm/mol or kg/kmol
The mass balance percentage from the above equation
The mass balance percentage from the above equation
100% glucose 51.14% ethanol + 48.86% carbon dioxide
So theoretical ethanol production from sucrose (100 kg) =51.14 / 0.78934 = 65 liters
So theoretical ethanol production from sucrose (100 kg) =51.14 / 0.78934 = 65 liters
Fermentation is a biochemical process in which organic compounds are converted into simple organic compounds released by microorganisms under the influence of enzymes.
Theoretical yield = (molasses consumed x fermentable sugar % * 650) / 100
Thus, one ton of fermentable sugar will yield 650 liters of absolute alcohol.
Practical yield = (total wash times x percent alcohol per wash) / 100
Distillation efficiency is the ratio between the mass of ethanol in the final product and the mass of ethanol in the distillery feed (wash).
Distillation efficiency is the ratio of actual alcohol production to the alcohol obtained in the distilled wash.
Actual alcohol production
Alcohol in wash distillation)
Various raw materials in the sugar process for ethanol production
Ethanol yield from different feedstocks available in the cane sugar process
Primary juice / Mixed juice / Secondary juice
B heavy molasses / final molasses
Ethanol production from sugarcane juice (mixed juice / clarified juice / secondary juice)
Reducing sugars (RS)
Ethanol production from sugarcane molasses (B heavy and final molasses)
One example is B heavy molasses
Material Brix
Material Brix
Cleanliness of the material
Cleanliness of the material
Reducing the percentage of sugars (RS)
Non-fermentable sugars (UFS)
Non-fermentable sugars (UFS)
Fermentation efficiency (FE)
Fermentation efficiency (FE)
Fermentation efficiency (FE)
Fermentation efficiency (FE)
Fermentation efficiency (FE)
(Brix) x (purity) / 100
(Brix) x (purity) / 100
Total Reducing Sugar (TRS)
Total Reducing Sugar (TRS)
Sucrose % + reducing sugars %
Sucrose % + reducing sugars %
Fermentable Sugars (FS)
Fermentable Sugars (FS)
Ethanol yield
Ethanol yield
Approximate values of different feed stocks in the sugar process
Name of feed stock
Cleanliness
Brix%
Reduces sugar % by weight
Non-fermentable sugars by weight
Primary juice
Secondary juice
Mixed juice
Mixed juice
Clarified juice
B Heavy molasses
B Heavy molasses
The ultimate molasses
Online calculator for ethanol yield
Advantages of using clear juice as feedstock for ethanol production:
1. Clean substrate compared to molasses, so juice fermentation provides good fermentation speed and efficiency.
3. The alcohol quality of the clear juice is better than that of alcohol obtained from molasses.
4. Sugarcane does not have high dissolved solids, so there is no scaling and blocking in the distillation column because it is formed using molasses.
5. Fermentation time is less than molasses fermentation time.
6. The color of the wastewater is less compared to the spent washing from the production of molasses alcohol.
Some disadvantages of using juice as a raw material for alcohol production:
Sugarcane juice cannot be stored in bulk for a long time because it is highly contaminated with bacteria and the yeast starts to ferment spontaneously very quickly.
3. During the crushing process, cane juice is usually quickly infected with bacteria and yeast.
So mixed juice is not desirable directly for fermentation.
It is better to go for the juice of the first or second effect
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