Ethanol production from various feedstocks in sugar process |Ethanol Yield

Ethanol production from various feed-stocks in sugar process | Yield of Ethanol

Calculating Yield of Ethanol from Sucrose and its Process Intermediate Products

This Article explained about calculation of ethanol yield from various feed stocks (Intermediate products) in sugar manufacturing process like sugarcane juice, secondary juice, syrup, A-molasses, B- heavy molasses and final molasses .. etc.

Calculating theoretical yield of ethanol from sucrose

The chemical equation from sucrose to ethanol can be written as ( Stoichiometric Equation )

C₁₂ H₂₂O₁₁ + H₂O $\overset{Invertage \ (or) \ \ H^+}{\rightarrow}$ C₆ H₁₂ O₆ + C₆ H₁₂ O₆ $\overset{Zymase}{\rightarrow}$ 4 C₂H₅ OH + 4 CO₂

Sucrose $\rightarrow$ Glucose + Fructose $\rightarrow$ Ethanol (Ethyl Alcohol)

Molecular weight of sucrose – 342.30 gm/mol or kg/kmol
Molecular weight Glucose/Fractrose – 180.16 gm/mol or kg/kmol
Ethyl Alcohol Molecular weight – 46.07 gm/mol or kg/kmol
Molecular weight of carbon dioxide – 44.01 gm/mol or kg/kmol

Molar mass balance (kmol x kg/kmol)

1 x 342.30 $\rightarrow$ 4 x 46.07 + 4 x 44.01

Mass balance percentage of the above equation

100% of Sucrose $\rightarrow$ 53.84% ethanol + 51.43 % carbon dioxide

The density of anhydrous ethanol (100%) is 0.78934 Kg/L at 20°C

So Theoretical ethanol production from sucrose (100 kg) = 53.84 / 0.78934 = 68.2 Liters

Calculating theoretical yield of ethanol from glucose/Fructose (Reducing Sugars)

The chemical equation from reducing sugars to ethanol can be written as ( Stoichiometric Equation )

C₆ H₁₂ O₆ $\overset{Zymase}{\rightarrow}$ 2 C₂H₅ OH + 2 CO₂

Glucose/Fructose $\rightarrow$ Ethanol (Ethyl Alcohol)

Molecular weight Glucose/Fractrose – 180.16 gm/mol or kg/kmol
Ethyl Alcohol Molecular weight – 46.07 gm/mol or kg/kmol
Molecular weight of carbon dioxide – 44.01 gm/mol or kg/kmol

Molar mass balance (kmol x kg/kmol)

1 x 180.16 $\rightarrow$ 2 x 46.07 + 2 x 44.01

Mass balance percentage of the above equation

100% of Glucose $\rightarrow$ 51.14% ethanol + 48.86 % carbon dioxide

The density of anhydrous ethanol (100%) is 0.78934 Kg/L at 20°C

So Theoretical ethanol production from sucrose (100 kg) =51.14 / 0.78934 = 65 Liters

Fermentation Efficiency:

Fermentation is bio chemical process in which organic compounds converted in to simple organic compound by enzymes which is secreted by micro-organism.

The ratio between Practical yield to Theoretical yield

Theoretical Yield = (Molasses consumed x Fermentable sugar % * 650) / 100

Hence One ton Fermentable sugar will give 650 Liters of Absolute alcohol.

Practical Yield = (Total wash production x Alcohol percentage in wash) / 100

Fermentation Efficiency $= \ \frac{ Practical \ \ Yield}{Theoretical \ \ Yield} \ \times \ 100$

Distillation efficiency :

The distillation efficiency is the ratio of the mass of ethanol in the final product to the mass of ethanol in the feed (wash) to the distillery.

Distillation Efficiency is the ration of Actual Alcohol production to Alcohol in wash distilled

Actual Alcohol Production $= \frac{ Alcohol \ \ production \ \times \ Alcohol \ \ proof}{175}$

Hence 175 proof is equal to 100 percentage alcohol (Absolute Alcohol)

Alcohol in Wash Distilled $= \frac{ Wash \ \ Distilled \times \ Alcohol \ percentage \ in \ wash} {100}$ )

Distillation Efficiency $= \frac{ Actual \ Alcohol \ Production} {Alcohol \ in \ Wash \ Distilled} \ \times \ 100$

Overall Efficiency

Fermentation efficiency * $= \frac{ Fermentation \ Efficiency \ \ \times \ Distillation \ \ Efficiency}{100}$

Various feed stocks in sugar process for ethanol production

The yields of ethanol from various feed-stocks available in a cane sugar process

Primary Juice / Mixed juice / Secondary juice

Clarified juice/ Concentrated clear juice (Syrup)

B Heavy Molasses / Final Molasses

Ethanol production from sugarcane juice (Mixed juice / Clarified Juice/ Secondary juice )

Taken one example:

S.NO	Particulars	UOM	Mixed Juice	Remarks
1	Brix of the Material	^oC	14.5	13 to 16
2	Purity of the material	%	81	78 to 84
3	Reducing Sugars (RS)	%	0.6	0.5 to 0.7
4	Un Fermentable Sugars (UFS)	%	0.1	0.1 to 0.2
5	Fermentation Efficiency (FE)	%	90	88 to 91
6	Distillation Efficiency (DF)	%	98.5	98 to 99%
7	Sucrose % (Pol)	%	11.745	(Brix) x (Purity ) / 100
8	Total Reducing sugars (TRS)	%	12.345	Sucrose % + Reducing Sugars%
9	Fermentable sugars (FS )	%	12.245	TRS – UFS
10	Yield of Ethanol	Ltrs/MT	71	FS x 0.65 x FE x DF x 10)

Ethanol production from sugarcane molasses (B Heavy and Final Molasses)

Taken one example for B-Heavy molasses

S.NO	Particulars	UOM	B – Heavy Molasses	Remarks
1	Brix of the Material	^oC	83	78 to 85
2	Purity of the material	%	49	45 to 55
3	Reducing Sugars percent (RS)	%	12	10 to 14%
4	Un Fermentable Sugars (UFS)	%	1.2	1 to 1.5%
5	Fermentation Efficiency (FE)	%	90	88 to 91
6	Distillation Efficiency (DF)	%	98.5	98 to 99%
7	Sucrose % (Pol)	%	40.67	(Brix) x (Purity ) / 100
8	Total Reducing Sugars (TRS)	%	52.67	Sucrose % + Reducing Sugars%
9	Fermentable Sugars (FS )	%	51.47	TRS – UFS
10	Yield of Ethanol	Ltrs/MT	297	FS x 0.65 x FE x DF x 10)

Approximate values of Various Feed Stocks in sugar process

Name of Feed Stock	Purity	Brix%	Pol% (sucrose)	Reducing sugars % by weight	Unfermentable sugars by Weight	Approx.Sp. Gravity
Primary juice	80 to 86	16 to 22	12 to 18	0.5 to 0.8	0.2 to 0.5	1.071
Secondary juice	78 to 86	10 to 14	7 to 12	0.2 to 0.5	0.2 to 0.4	1.043
Mixed juice	78 to 86	12 to 15	9 to 13	0.4 to 0.8	0.2 to 0.4	1.056
Clarified juice	78 to 86	12 to 15	9 to 13	0.4 to 0.8	0.2 to 0.4	1.061
B Heavy Molasses	48 to 55	78 to 84	36 to 47	10 to 14	1 to 1.5	1.4
Final Molasses	28 to 34	88 to 92	25 to 32	12 to 18	1.2 to 2	1.4

Online Calculator for Yield of Ethanol

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Advantages while using Clear juice as a feed stock of Ethanol production:

1. Clean substrate as compared to molasses therefore juice fermentation gets good fermentation rate & efficiency.

2. Biochemical Oxygen Demand (BOD) & Chemical Oxygen Demand (COD) of the effluent will be much less as compared to molasses; therefore effluent treatment cost is very less.

3. Quality of the alcohol from clear juice is better than the alcohol drawn from molasses.

4. Cane does not have high content of dissolved solids and therefore there is no scaling and blocking in distillation column as it forms with the use of molasses.

5. Fermentation time less than the fermentation time taken by the molasses.

6. Colour of the effluent is less compared to spent wash from molasses based alcohol production.

Some Disadvantages while using Juice as a feed stock of production of Alcohol :

1 . The cane juice cannot be stored in bulk for any considerable length of time as it is highly contaminated with bacteria & yeast starts to ferment spontaneously very rapid.

2. This means the distillery unit must be located in close proximity to the cane mill

3. Cane juice normally becomes quickly infected with bacteria and yeast in the crushing process. So Mixed juice not preferable to directly take fermentation. It is better to go first effect or second effect juice

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Post Author: siva alluri

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35 thoughts on “Ethanol production from various feed-stocks in sugar process | Yield of Ethanol”

Amresh

(September 1, 2018 - 5:37 pm)

100% of Sucrose = 53.84% ethanol + 51.43 % carbon dioxide

How possible elaborate please.

siva alluri

(September 2, 2018 - 3:26 pm)

According to Stoichiometric Equation
C12 H22O11 + H2O = 4 C2H5 OH + 4 CO2

1 x 342.30 = 4 x 46.07 + 4 x 44.01

Now consider sucrose 1 gm then
1 = (4 x 46.07/ 342.30 ) + ( 4 x 44.01 / 342.30) = 0.5383 + 0.5143

BHARATKUMAR MAGDUM

(September 24, 2018 - 5:02 pm)

Good calculation Madam, But ethanol production from B heavy ,& final molasses is approximately equal (20 lit difference) so what is the profit from B heavy molasses
Thank you for your valuable calculation

siva alluri

(September 24, 2018 - 5:52 pm)

For BH and final molasses yield approximately differ 50 to 60 Lt./MT

mahbub rahman

(December 23, 2018 - 6:34 pm)

good article <3

siva alluri

(December 26, 2018 - 4:28 pm)

Thank you Mr.mahbub rahman

Rajani Hazarika

(December 27, 2018 - 3:34 pm)

We are going to setup a sugarcane based Ethanol plant. So, these are very helpful to. us.
Thanks
Rajani Hazarika
Zest Green Energy
Assam
email
zestgreenenergy@gmail.com

siva alluri

(December 29, 2018 - 5:10 pm)

Thank you Mr.Rajani Hazarika

Ankit

(March 14, 2019 - 3:24 pm)

Send all calculation of meterial balance

Ankit

(March 15, 2019 - 6:43 pm)

Send all calculations of grain based distillery

siva alluri

(March 21, 2019 - 3:04 pm)

We will provide soon

Harshal

(February 15, 2020 - 4:11 pm)

Send all calculation of meterial balance and fermentation calculation

Sanaullah

(April 10, 2019 - 3:33 pm)

It’s a good calculation and elaboration on fermentation of various feed stocks.
what should be the optimum mix of secondary mill juice and C molasses for a distillery designed for C molasses?

siva alluri

(April 13, 2019 - 5:32 pm)

It is only depended upon total fermentable sugars after mixing the juice and final molasses

VijayKumar Dure

(July 11, 2019 - 2:06 pm)

Sirjii pls send including Syrup based example

siva alluri

(July 14, 2019 - 4:57 pm)

For syrup also we apply same procedure
According to syrup properties we applied the values ( i.e Brix of the Material , Purity of the material , Reducing Sugars percent (RS) , Un fermentable sugars (UFS) )