Process Evaluation and Design II – Spring 2016

Process Evaluation and Design II – Spring 2016

CHEG 407 – A

CASE 2: PROCESS DESIGN FOR ETHANOL

PRODUCTION FROM SUGARCANE

Instructor: Dr. Jacob R. Borden

Submitted by:

An Minh Tran

College of Engineering and Technology

McNeese State University

Date Submitted: May 6, 2016

2

Table of Contents

Executive Summary.........................................................................................................................3

Introduction......................................................................................................................................3

Overall Process Description............................................................................................................3

Mass and Energy Balance…………………...........................…………………………………….4

A. Milling…………………..………………..…………………………………………….4

B. Juice Clarification………………………..…………………………………………….5

C. Fermentation…………………………………………………………………………...7

D. Ethanol Distillation………………………………………………………………….....8

Major Equipment List and Purchased Cost…………………………………………………….....9

Project Economics……………………………………………………………………………….11

A. Annual Depreciation………………………………………………………………….11

B. Variables Cost of Production…………………………………………………………11

C. Annual Labor, Maintenance, and Fixed Charges……………………………………..12

D. Variables cost per gallon ethanol production…………………………………………13

E. Cash Flow and NPV Analysis………………………………………………………...13

Safety Concerns………………………………………………………………………………….14

A. Over Process………………………………………………………………………….14

B. Hazard and Operability Study (HAZOP)……………………………..………………15

Environment…………………………………………..………………………………………….17

Conclusion and Recommendation.................................................................................................17

3

EXECUTIVE SUMMARY

Production ethanol from sugarcane included of four process: milling, juice clarification,

fermentation, and ethanol distillation. In this report, a process design for the production of

ethanol from sugarcane at St. Mary Sugar Coop plant in Jeanerette, Louisiana is introduced.

With the basic is 20,000 US ton/day of raw sugarcane that is running in 150 days/year to produce

1569 US ton/day or 71.5 MM gal/year of ethanol, the mass and energy balance, cost of major

equipment, cash flow and NPV analysis up to twenty years, and safety concern for whole of the

process are presented in this report. With the price of ethanol is $2.03/gal, the total equipment

cost is $21 MM, the revenue each year is $145 MM, tax is 34% net income, using 7% internal

rate of return, the net present value at the end of year 20th is $60MM.

INTRORUCTION

Ethanol is one of the most important substances that is used in different area such as a solvent in

producing perfumes, or making medicines and drugs. Moreover, ethanol is used as a fuel and

gasoline additive. Louisiana is one of the main states in the US that produce many important

substances from ethanol; and St. Mary Sugar Coop plant in Jeanerette, Louisiana is one of the

biggest plant of producing ethanol from sugarcane.

OVERALL PROCESS DESCRIPTION

The basic of the process is 20,000 US ton/day of sugarcane that is operated in 150 days/years to

produce ethanol. There are four main sections to produce ethanol from sugarcane. The first

section is cane milling where sugar is leached out from the bagasse through milling sugarcane.

The second section is juice clarification that is clarified juice is made from clean juice through

multi evaporators. The third section is fermentation which ethanol solution is produced with 15%

wt of ethanol, and the last section is ethanol distillation that produces 50% wt of ethanol in final

4

product of ethanol solution. The figure below is present whole process of producing ethanol from

sugarcane at St. Mary Sugar Coop plant in Jeanerette, Louisiana.

Figure 1: Overall Process Flow Diagram of System

MASS AND ENERGY BALANCE

A. Milling

Figure 2: Milling Process Flow Diagram

In the milling process, 20,000 US ton/day of raw sugarcane is broken using knife mill and

hammer mill, then the crushed cane are grinded using three set of roller mill. 9000 US ton/day of

water is applied at the third roller mill and is transported to 2nd and the 1st mill for more extration

5

of juice. The 6400 US ton/day with 40% solid and 60% moisture of bagasse comes from the third

mill is combusted by boiler to generate steam and electricity. After the milling process, 22,600

US ton/day raw juice with 14.7% wt% sugar and 84% wt% water is produced and is transported

to setting tank of juice clarification process.

The figure 3 and figure 4 are present for mass balance and energy of the boiler of milling section.

Figure 3: Mass Balance of Milling Process

Table 1: Energy of Boiler

For 6400 US ton/day with 40% solid and 60% moisture of bagasse, at P = 1 bar, the heat duty of

boiler that need to combusted that amout of bagasses is Q = 121,287.32 kW.

B. Juice Clarification

P 1 barm water 3483590.4 kg/dayT in 20 CT sat 99.61 Cdelta H 2675 kJ/kgCp 4.185 kJ/kg-KQ 121,287.32 kW

6

Figure 4: Juice Clarification Process Flow Diagram

The 22,600 US ton/day of raw juice coming to setting tank is transported to filter to eliminate

mud; then that clean juice with 15% wt% sugar and 85% wt% water is going to multi evaporator

with 12,439 US ton/day of steam to heat water and concentrated juice. In the concentrated juice,

the percent weight of sugar is 30% and percent weight of water is 70%. It means this process is

eliminated 11,289.6 US ton/day of water to make the juice to be more purity. It helps the

reactions in the next section that produce ethanol solution is reacted easier.

Figure 5 and figure 6 are shown in mass and energy balance of juice clarification process.

Figure 5: Mass Balance of Juice Clarification Process

7

Figure 6: Energy Balance of Juice Clarification Process

For three evaporator are used in this process, total heat duty equals to 265,413 kW, and the heat

transfer coefficient is assumed 4000 W/m2-K (from chemical book), the area for eat evaporator

equals 250 m2. This number will be used to calculate the equipment cost for evaporator.

C. Fermentation

Figure 7: Fermentation Process Flow Diagram

Fermentation process is process to produce ethanol composition based on these following equations:

Inversion of sucrose by hydrolysis:

C12 H22O11+H2 O→ 2C6 H12O6

8

¿conversion of invert sugarsby yeast :

2C6 H12O6 → 4C2 H5OH +4 C O2

Following by these above equations, after 11,072 US ton/day of concentrated juice with 30%

wt% sugar coming out of reactor, the yeast of 11,072 US ton/day of yeast that 14% wt%

ethanol is produced. Then, it is transported to centrifugal; and the ethanol solution with 15%

wt% ethanol, 71% wt% water and 14% wt% CO2 is produced to lead to stripping column.

Figure 8 is show in mass balance of fermentation process.

Figure 8: Mass Balance of Fermentation Process

D. Ethanol Distillation

Figure 9: Ethanol Distillation Process Flow Diagram

Ethanol distillation process is the last process of ethanol production from sugarcane process.

Ethanol solution from previous process coming to stripping column to eliminate carbon dioxide;

9

then next will lead to distillation column. After eliminate carbon dioxide in the solution, 9000

US tons/day of ethanol solution will have 17% wt% ethanol and the rest is water. And distillation

process will increase the purity of ethanol to be 50% wt%, which means 1569 US ton or 71.5

MM gallons of ethanol is produced per day.

Figure 10: Mass Balance of Ethanol Distillation Process

Figure 11: Energy Balance of Ethanol Distillation Process

Ethanol solution is cooled by cooling water of the condenser. The total heat duty of the

condenser equals 157,986 kW, and with the heat transfer coefficient equals 3000 W/m2-K. The

area of the condenser is 2178.3 m2.

MAJOR EQUIPMENT LIST AND PURCHASED COST

10

Most of the unit to calculate major equipment of the process is calculated by mass and energy

balance equations that are shown above. And some of other units equipment that are used to

calculate the cost of setting tank, filter, centrifuge, stripping column, and distillation column are

shown in the figure 12 below.

Figure 12: Cost Equipment Calculation Units

Based on those units value above, and other units value that are calculate in mass and energy

balance part, the total cost of major equipment is estimated following by table 1 below.

11

Table 2: Total Equipment Cost for whole Process

The total equipment cost for whole process equals $20.7MM

PROCESS ECONOMICS

A. Annual Depreciation

Annual depreciation is calculated by straight-line depreciation with the salvage value of all

equipment is estimated to be 15% of the equipment cost with the expected life of the

equipment is 20 years.

Total Equipment Cost $ 20,659,256.34 Salvage Value (15% Tot. Equip. Cost) $ 3,098,888.45 Depreciable Asset Cost $ 17,560,367.89 Depreciation Rate/Year (20 years) 5%Annual Depreciation $ 878,018.39

Table 3: Annual Depreciation

Annual depreciation of the process equals $0.88MM

B. Variables Cost of Production

To calculate variables cost of production, the number of water comes from cooling water of

condenser and steam for the boiler, and natural gas is used for the boiler to heat water the run the

system. 101,335 US ton/day equals 24.3 MM gal/day of water is used.

12

Utilities Consumption/day Cost $/unit Cost $/day Cost $/yearWater (gal) 24,285,377.26 0.005 121,426.89 18,214,032.94

Electricity (kWh) 624,987.00 0.06 37,499.22 5,624,883.00Natural - gas (MM BTU) 10,107.28 2.178 22,013.65 3,302,047.35

Raw Material Consumption/day Cost $/unit Cost $/day Cost $/yearSugarcane (US ton) 20,000 30 600,000 90,000,000.00

Total variable cost $/year $ 117,140,963.29Table 4: Variable Cost of Production

The total variable cost per year of the process is $118 MM.

C. Annual Labor, Maintenance, and Fixed Charges

The calculation for annual labor, maintenance, and fixed charged are shown in table below with

the maintenance charged are 5% of the initial total equipment cost, and fixed charges excluding

depreciation are 10% of the initial total equipment cost.

Number of operators/shift 18Operator salary $/h 20Number of engineers 3Engineer Salary/season 25000Plant Manager 1Manager salary/season 40000Over head 100% labor cost Total labor cost $/year $ 3,512,000.00 Maintenance (5% Total equipment cost/year) $ 1,032,962.82 Fixed Charge ( 10% Total equipment cost/year) $ 2,065,925.63

Table 5: Annual Labor, Maintenance, and Fixed Charges

D. Variables cost per gallon ethanol production

From all the costs that are calculated above, with 1569 US tons/day or 71.5 MM gal/day of

ethanol, the variables cost per gallon from ethanol production is shown in table below

13

Table 6: Variable Cost per Gallon Ethanol Production

E. Cash Flow and NPV Analysis

The sell price of ethanol is $2.03/gal with 71.5 MM gal/year of ethanol is produced, the revenue

of this project is $145 MM/year. Net Present Value (NPV) method is applied to assess the

economic value of the project. A common Internal Rate of Return (IRR) of 7% is used for

calculation. Tax is incorporated and equals 34% of the net income. The NPV of this plant is

calculated in 20 years.

Cost Revenue Tax Cash Flow NPV Total NPV to year

0 $ 20,659,256.34     $ (20,659,256.34) $ (20,659,256.34) $ (20,659,256.34)

1 $ 124,629,870.14 $ 145,116,194.90 $ 6,965,350.42 $ 13,520,974.34 $ 12,574,506.14 $ (8,084,750.20)

2 $ 124,629,870.14 $ 145,116,194.90 $ 6,965,350.42 $ 13,520,974.34 $ 10,688,330.22 $ 2,603,580.01

3 $ 124,629,870.14 $ 145,116,194.90 $ 6,965,350.42 $ 13,520,974.34 $ 9,085,080.69 $ 11,688,660.70

4 $ 124,629,870.14 $ 145,116,194.90 $ 6,965,350.42 $ 13,520,974.34 $ 7,722,318.58 $ 19,410,979.28

5 $ 124,629,870.14 $ 145,116,194.90 $ 6,965,350.42 $ 13,520,974.34 $ 6,563,970.80 $ 25,974,950.08

6 $ 124,629,870.14 $ 145,116,194.90 $ 6,965,350.42 $ 13,520,974.34 $ 5,579,375.18 $ 31,554,325.26

7 $ 124,629,870.14 $ 145,116,194.90 $ 6,965,350.42 $ 13,520,974.34 $ 4,742,468.90 $ 36,296,794.16

8 $ 124,629,870.14 $ 145,116,194.90 $ 6,965,350.42 $ 13,520,974.34 $ 4,031,098.56 $ 40,327,892.72

9 $ 124,629,870.14 $ 145,116,194.90 $ 6,965,350.42 $ 13,520,974.34 $ 3,426,433.78 $ 43,754,326.50

10 $ 124,629,870.14 $ 145,116,194.90 $ 6,965,350.42 $ 13,520,974.34 $ 2,912,468.71 $ 46,666,795.21

11 $ 124,629,870.14 $ 145,116,194.90 $ 6,965,350.42 $ 13,520,974.34 $ 2,475,598.41 $ 49,142,393.62

12 $ 124,629,870.14 $ 145,116,194.90 $ 6,965,350.42 $ 13,520,974.34 $ 2,104,258.65 $ 51,246,652.27

13 $ 124,629,870.14 $ 145,116,194.90 $ 6,965,350.42 $ 13,520,974.34 $ 1,788,619.85 $ 53,035,272.11

14 $ 124,629,870.14 $ 145,116,194.90 $ 6,965,350.42 $ 13,520,974.34 $ 1,520,326.87 $ 54,555,598.99

15 $ 124,629,870.14 $ 145,116,194.90 $ 6,965,350.42 $ 13,520,974.34 $ 1,292,277.84 $ 55,847,876.83

16 $ 124,629,870.14 $ 145,116,194.90 $ 6,965,350.42 $ 13,520,974.34 $ 1,098,436.16 $ 56,946,312.99

17 $ 124,629,870.14 $ 145,116,194.90 $ 6,965,350.42 $ 13,520,974.34 $ 933,670.74 $ 57,879,983.73

18 $ 124,629,870.14 $ 145,116,194.90 $ 6,965,350.42 $ 13,520,974.34 $ 793,620.13 $ 58,673,603.86

19 $ 124,629,870.14 $ 145,116,194.90 $ 6,965,350.42 $ 13,520,974.34 $ 674,577.11 $ 59,348,180.97

  $/year $/gal of Ethanol Utilities $ 27,140,963.29 $ 0.38 Raw Material $ 90,000,000.00 $ 1.26 Depreciation $ 878,018.39 $ 0.01 Labor $ 3,512,000.00 $ 0.05 Maintenance $ 1,032,962.82 $ 0.01 Fixed Charge $ 2,065,925.63 $ 0.03 Total $ 124,629,870.14 $ 1.74

14

20 $ 124,629,870.14 $ 145,116,194.90 $ 6,965,350.42 $ 13,520,974.34 $ 573,390.54 $ 59,921,571.51

Table 7: Cash Flow and NPV Analysis

The NPV of this plant after 20 years is $60 MM. The payback period is 1 years; the profit being

earned on the second year. With the NPV equal $60 MM, which is 3 of the capital investment,

this project is worth implementing.

SAFETY CONCERN

A. Overall Process

The plant produces ethanol from sugarcane. Ethanol is a highly flammable; therefore, the

prevention for this plant, especially at fermentation and ethanol distillation process are no open

flames, no sparks, no smoking or contact with strong oxidants at that area. The acute hazards of

ethanol that effects to human body such as cough, headache, fatigue, drowsiness, dry skin,

redness, pain, or burning eyes; therefore, when people working with areas that have high

concentration of ethanol, they need to wear breathing protect, also protective gloves, and safety

goggles, specially, prevention eating, drinking, or smoking during work.

15

B. Hazard and Operability Study (HAZOP)

Table 8: Hazard and Operability Study (HAZOP)

16

0 1 2 3 4 5 6 7 8 9 100123456789

10

1, 2

3

4

5

6

7, 8

Boston Square for Clean Juice of Evaporator

Likelihood

Seve

rity

Figure 13: Boston Square for Clean Juice of Evaporator

0 1 2 3 4 5 6 7 8 9 100123456789

10

9, 13

10, 14, 15

1611

12

Boston Square for Reactor and Stripping Column

Concentrated Juice of Reactor" Ethanol Solution of Stripping Column

Likelihood

Seve

rity

Figure 14: Boston Square for Reactor and Stripping Column

17

0 1 2 3 4 5 6 7 8 9 100

1

2

3

4

5

6

7

8

9

10

17

18, 24 19, 20, 23

2122

Boston Square for Cooling Water of Condenser

Likelihood

Seve

rity

Figure 15: Boston Square for Cooling Water of Condenser

ENVIROMENT

This process produces ethanol, and also carbon dioxide, one of the harmful gas that give negative

effects to environment. The high concentration of carbon dioxide in the atmosphere will increase

the temperature of atmosphere. And this is the cause for GREEN HOUSE EFFECT. The higher

temperature of atmosphere also affect to the climate and affect the life being. The temperature is

increasing average 1oC each year. It cause the melting polar ice caps and glaciers; so increase

ocean water level; hence affects to wild life.

CONCLUSION and RECOMMENDATION

This report presents the process of producing 71.5 MM gallons of ethanol per year from the basic

is 20,000 US tons of sugarcane per day. The total capital cost of the project is $21MM, and

annual $125 MM cost for production. The sell price of ethanol is $2.03/gal with 71.5 MM

18

gal/year of ethanol is produced, the revenue of this project is $145 MM/year. The payback period

of this project is one year and the project starts to earn profit from 2nd year. At the end of 20th

year, NPV is $60 MM. The recommendation for this project is adding a treatment system for

carbon dioxide to reduce amount of carbon dioxide to environment, also can use it to produce

soft drink such as coke or diet coke.