1. Process Evaluation and Design II – Spring 2016
Process Evaluation and Design II – Spring 2016
CHEG 407 – A
CASE 3: PRODUCTION FRESH WATER FROM SEA
WATER BY MULTI-EFFECT EVAPORATOR SYSTEM
Instructor: Dr. Jacob R. Borden
Submitted by:
An Minh Tran
College of Engineering and Technology
McNeese State University
Date Submitted: May 3, 2016

2. 2
Table of Contents
Executive Summary........................................................................................................................ 3
Introduction..................................................................................................................................... 3
Overall Process Description............................................................................................................ 3
Process with one Effect Evaporator System...........................…………………………………….4
A. Mass and Energy Balance………………..…………………………………………….5
B. Major Equipment List and Purchased Cost…………………………………………….8
C. Project Economics……………………………………………………………………...9
Process with three Effects Evaporator System……………………………………………..........11
A. Mass and Energy Balance…………………………………………………………….11
B. Major Equipment List and Purchased Cost…………………………………………...15
C. Project Economics…………………………………………………………………….16
Process with four Effects Evaporator System……………………………………………………19
A. Mass and Energy Balance…………………………………………………………….19
B. Major Equipment List and Purchased Cost…………………………………………...22
C. Project Economics…………………………………………………………………….24
Process with six Effects Evaporator System……………………………………………………..27
A. Mass and Energy Balance…………………………………………………………….27
B. Major Equipment List and Purchased Cost…………………………………………...29
C. Project Economics…………………………………………………………………….31
Options…………………………………………………………………………………………...33
Safety Concerns ............................................................................................................................ 34
A. Over Process………………………………………………………………………….34
B. Hazard and operability study (HAZOP)………………………………………………35
Conclusion and Recommendation ................................................................................................ 36

3. 3
EXECUTIVE SUMMARY
This report is a process design for the production of fresh water from sea water that contains 3.5
wt% salt. A multi – effect evaporator system that includes of number of effect, 1 boiler, and 1
condenser is used in this process. This paper provides a basic plant design with process flow
diagram, mass and energy balance, total equipment cost, economics analysis, and safety concerns
of the plant. The plant design basis is 400,000 pounds of fresh water is produced per day,
operating 300 days per year. The expected life of the equipment is 10 years and salvage value of
all equipment is 15% of the total equipment cost. Depreciate the equipment is calculated by
straight-line depreciation. Fixed charged are 15% of the installed cost of the evaporators
excluding depreciation. Maintenance charges are 5% of the total equipment cost. In this report,
the economics analysis is used base on different system with 1 effect, 3 effects, 4 effects, and 6
effects; then which option will give the highest total NPV will be chose to design the plant.
INTRORUCTION
Water is very important for human’s life. People drink water everyday to survive. The plants
need water in their photosynthesis process. Many factories use water for their cooling system.
Electricity can also produce by water; and many application of water in the real life. However,
because of the climate change and the increasing of population, souce of fresh water from nature
such as river or ground water seems like not enough to provide for human life. Besides, sea
water is the unlimit souce of water from natural. Therefore, a multi-effect evaporator need to be
designed to desalinate sea water to fresh water to provide for human life is very necessary.
OVERALL PROCESS DESCRIPTION
Sea water that pump to each evaporator is heated by hot steam which comes from the boiler.
After heated by hot steam, sea water turns to be hot vapor and is lead to the next evaporator to

4. 4
heat the next sea water flow of next evaporator. The cooling water on the other hand is pumped
to boiler. On next evaporater the sea water fed and the sea water coming from first evaporator are
heated by the steam coming from same evaporator to produce fresh water. Similarly, the process
keeps continuous until it goes to the last evaporator. At the last evaporator, the steam is cooled
by cooling water of the condenser. The figure below shown in the flow diagram of the Process
with four effect evaporator is used to make fresh water from sea water.
Figure 1: Flow Diagram of four Effects Evaporator System
PROCESS WITH ONE EFFECT EVAPORATOR SYSTEM
A. Mass and Energy Balance
With pressure of the boiler P = 40 bar, pressure of the effect P = 30 bar, and pressure of
condenser P = 1 bar, the base is given for mass flowrate of fresh water is 400,000 lb/day and is
produced from sea water that contains 3.5 wt% salt, from the steam tables combine with mass

5. 5
and energy balance equations, the mass of brine coming out of effect, mass of cooling water
coming in to the condenser, mass of steam needed to heat up in the boiler, the heat duty of
natural gas that is required to heat up the steam in the boiler, the heat duty of condenser and its
area need to design to cool the hot stream are calculated.
Figure 2: Mass and Energy Balance Calculation for one Effect Evaporator System
Based on the values are calculated, the summary for mass and energy balance for the system is
shown in these figures below

6. 6
Figure 3: Mass Balance of the Process with one Effect Evaporator System
Figure 4: Energy Balance of the Boiler and one Effect Evaporator System

7. 7
Figure 5: Mass and Energy Balance of Condenser for one Effect Evaporator System
From those values of mass flowrate and heat duty that are calculated above, the unit such as
power of the pumps or area of evaporators are find out to estimate for equipment cost of the
project.
B. Major Equipment List and Purchased Cost
Figure 6: Cost Equipment Calculation for one Effect Evaporator System

8. 8
From those calculations that are presented above, the table of total equipment cost of process
is show in below
Name Unit of Size Value a b n Material Cost in 2010 Cost in 2016
Boiler Steam (liters/s) 9437.41 124000 10 1 Carbon Steel $ 218,374.07 $ 262,048.88
Condenser Area (m2) 64.01 1900 2500 1 Carbon Steel $ 161,929.16 $ 194,314.99
Effect 1 Area (m2) 40.29 330 36000 0.55 Carbon Steel $ 275,225.40 $ 330,270.48
Feed Pump Flow (liter/s) 2.12 8000 240 0.9 Carbon Steel $ 8,471.31 $ 10,165.57
Pump 1 Flow (liter/s) 3.19 800 240 0.9 Carbon Steel $ 8,681.82 $ 10,418.18
Total Equipment Cost $ 807,218.10
Table 1: Total Equipment Cost for one Effect Evaporator System
The total equipment cost for the process system with one evaporator equals $807,218.
C. Project Economics
1) 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 10 years.
Total Equipment Cost $ 807,218.10
Salvage Value $ 121,082.72
Depreciable Asset Cost $ 686,135.39
Depreciation Rate/Year 10%
Annual Depreciation $ 68,613.54
Table 2: Annual Depreciation for one Effect Evaporator System
Annual depreciation for one effect evaporator system is $68,613.54
2) 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, electricity is used for the feed pump of sea water, and natural
gas is used for the boiler to heat water the run the system.
Utilities Consumption/day Cost $/unit Cost $/day Cost $/year
Water (gal) 3,953,301.72 0.005 19,766.51 5,929,952.58
Electricity (kWh) 731,531.69 0.046 33,650.46 10,095,137.39

9. 9
Natural – gas (MM BTU) 714.69 2.178 1,556.60 466,981.00
Total variable cost $/year 16,492,070.97
Table 3: Variables Cost of Production for one Effect Evaporator System
From the table above, the main costs that effect to the variables cost of production are cost of
cooling water for the condenser and cost of electricity for the sea water feed pump. However,
based on mass balance, to produce 400,000 lb/day of fresh water, the flowrate of sea water is
414,508 lb/day, which is 2.12 liters/s, and this value is constant, so the electricity cost is
constant; therefore, the main utilities that effects to the changing variables cost of production is
volume flowrate of cooling water.
3) 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 15% of the installed cost of the evaporators
Number of operators/shift 2
Operator salary $/hr 15
Number of engineers 1
Engineer Salary/season 25000
Over head 100% labor cost
Total labor cost $/year $ 632,000.00
Maintenance (5% Total equipment cost/year) $ 40,360.91
Fixed Charge ( 15%installed evaporator cost) $ 49,540.57
Table 4: Annual Labor, Maintenance, and Fixed Charges
4) Variables cost per gallon fresh water production
From all the costs that are calculated above, with 400,000 lb/day or 14.3 MM gal/day of fresh
water produce, the variables cost per gallon fresh water production is shown in table below
$/year $/gal of Water
Utilities $ 16,492,070.97 $ 1.15
Depreciation $ 74,892.38 $ 0.01
Labor $ 632,000.00 $ 0.04
Maintenance $ 40,360.91 $ 0.00

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Fixed Charge $ 49,540.57 $ 0.00
Total $ 17,288,864.83 $ 1.20
Table 5: Variables cost per gallon fresh water production
From the table above, the cost of utilities is the highest cost that need to spend for the process.
5) Cash Flow and NPV Analysis
A cash flow analysis is done based on Annual Depreciation, Variables Cost of Production,
Annual Labor, Maintenance, and Fixed Charges for this project with the total is equal $17MM
each year. Net Present Value (NPV) method is applied to assess the economic value of the
project. A common Internal Rate of Return (IRR) of 8.5% is used for calculation. Tax is
incorporated and equals 28% of the net income. Desalinated water is sold for $1/gal. 400,000
lb/year or 14.3 MM gal/year of fresh water is produced. It means the revenue of this project
equals $14.3MM. The NPV of this plant is calculated in 10 years.
Year Cost Revenue Tax Cash Flow NPV Total NPV to year
0 $ 807,218.10 $ (807,218.10) $ (807,218.10) $ (807,218.10)
1 $ 17,288,864.83 $ 14,392,090.56 $ (811,096.79) $ (2,085,677.47) $ (1,772,825.85) $ (2,580,043.95)
2 $ 17,288,864.83 $ 14,392,090.56 $ (811,096.79) $ (2,085,677.47) $ (1,506,901.97) $ (4,086,945.93)
3 $ 17,288,864.83 $ 14,392,090.56 $ (811,096.79) $ (2,085,677.47) $ (1,280,866.68) $ (5,367,812.60)
4 $ 17,288,864.83 $ 14,392,090.56 $ (811,096.79) $ (2,085,677.47) $ (1,088,736.68) $ (6,456,549.28)
5 $ 17,288,864.83 $ 14,392,090.56 $ (811,096.79) $ (2,085,677.47) $ (925,426.17) $ (7,381,975.46)
6 $ 17,288,864.83 $ 14,392,090.56 $ (811,096.79) $ (2,085,677.47) $ (786,612.25) $ (8,168,587.70)
7 $ 17,288,864.83 $ 14,392,090.56 $ (811,096.79) $ (2,085,677.47) $ (668,620.41) $ (8,837,208.11)
8 $ 17,288,864.83 $ 14,392,090.56 $ (811,096.79) $ (2,085,677.47) $ (568,327.35) $ (9,405,535.46)
9 $ 17,288,864.83 $ 14,392,090.56 $ (811,096.79) $ (2,085,677.47) $ (483,078.25) $ (9,888,613.71)
10 $ 17,288,864.83 $ 14,392,090.56 $ (811,096.79) $ (2,085,677.47) $ (410,616.51) $ (10,299,230.22)
Table 6: Cash Flow and NPV Analysis
Table above shown that the project is not profit if one desalinated water will sell for $1/gal for
one effect evaporator system.
PROCESS WITH THREE EFFECTS EVAPORATOR SYSTEM
A. Mass and Energy Balance

11. 11
With pressure of the boiler P = 40 bar, pressure of the 1st effect P = 30 bar, pressure of the 2nd
effect P = 20 bar, pressure of the 3rd effect P = 10 bar, and pressure of the condenser P = 1 bar,
the base is given for mass flowrate of fresh water is 400,000 lb/day and is produced from sea
water that contains 3.5 wt% salt, from the steam tables combine with mass and energy balance
equations, the mass of steam and brine coming out of each effect, mass of cooling water coming
in to the condenser, mass of steam needed to heat up in the boiler, the heat duty of natural gas
that is required to heat up the steam in the boiler, the heat duty of condenser and its area need to
design to cool the hot stream are calculated.

12. 12
Figure 7: Mass and Energy Balance Calculation for three Effects Evaporator System

13. 13
Based on the values are calculated, the summary for mass and energy balance for the system is
shown in these figures below
Figure 8: Mass Balance of the Process with three Effects Evaporator System

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Figure 9: Energy Balance of the Boiler and three Effects Evaporator System
Figure 10: Mass and Energy Balance of Condenser for three Effects Evaporator System
From those values of mass flowrate and heat duty that are calculated above, the unit such as
power of the pumps or area of evaporators are find out to estimate for equipment cost of the
project.
B. Major Equipment List and Purchased Cost

15. 15
Figure 11: Cost Equipment Calculation for three Effects Evaporator System
From those calculations that are presented above, the table of total equipment cost of process
is show in below
Name Unit of Size Value a b n Material Cost in 2010 Cost in 2016
Boiler Steam (liters/s) 4093.07 124000 10 1 Carbon Steel $ 164,930.69 $ 197,916.82
Condenser Area (m2) 20.90 1900 2500 1 Carbon Steel $ 54,154.69 $ 64,985.63
Effect 1 Area (m2) 17.47 330 36000 0.55 Carbon Steel $ 173,960.28 $ 208,752.33
Effect 2 Area (m2) 16.13 330 36000 0.55 Carbon Steel $ 166,457.58 $ 199,749.09
Effect 3 Area (m2) 12.00 330 36000 0.55 Carbon Steel $ 141,521.21 $ 169,825.46
Feed Pump Flow (liter/s) 2.12 8000 240 0.9 Carbon Steel $ 8,471.31 $ 10,165.57
Pump 1 Flow (liter/s) 1.38 800 240 0.9 Carbon Steel $ 8,321.47 $ 9,985.77
Pump 2 Flow (liter/s) 1.00 800 240 0.9 Carbon Steel $ 8,239.58 $ 9,887.50
Pump 3 Flow (liter/s) 0.74 800 240 0.9 Carbon Steel $ 8,182.22 $ 9,818.67
Total Equipment Cost $ 881,086.84
Table 7: Total Equipment Cost for three Effects Evaporator System
The total equipment cost for the process system with three effects evaporator system equals
$881,086.84
C. Project Economics
1) 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 10 years.
Total Equipment Cost $ 881,086.84
Salvage Value $ 132,163.03

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Depreciable Asset Cost $ 748,923.82
Depreciation Rate/Year 10%
Annual Depreciation $ 74,892.38
Table 8: Annual Depreciation for three Effects Evaporator System
Annual depreciation for three effect evaporator system is $74,892.38
2) 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, electricity is used for the feed pump of sea water, and natural
gas is used for the boiler to heat water the run the system.
Utilities Consumption/day Cost $/unit Cost $/day Cost $/year
Cooling water (gal) 1,063,043.26 0.005 5,315.22 1,594,564.88
Electricity (kWh) 731,531.69 0.046 33,650.46 10,095,137.39
Natural - gas (MM BTU) 309.97 2.178 675.11 202,532.89
Total variable cost $/year $ 11,892,235.16
Table 9: Variables Cost of Production for three Effects Evaporator System
From the table above, the main costs that effect to the variables cost of production are cost of
cooling water for the condenser and cost of electricity for the sea water feed pump. However,
based on mass balance, to produce 400,000 lb/day of fresh water, the flowrate of sea water is
414,508 lb/day, which is 2.12 liters/s, and this value is constant, so the electricity cost is
constant; therefore, the main utilities that effects to the changing variables cost of production is
volume flowrate of cooling water.
3) 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 15% of the installed cost of the evaporators
Number of operators/shift 4
Operator salary $/hr 15
Number of engineers 2

17. 17
Engineer Salary/season 25000
Plant Manager 1
Manager salary/season 37000
Over head 100% labor cost
Total labor cost $/year $ 1,560,000.00
Maintenance (5% Total equipment cost/year) $ 44,054.34
Fixed Charge ( 15% installed evaporator cost) $ 86,749.03
Table 10: Annual Labor, Maintenance, and Fixed Charges
4) Variables cost per gallon fresh water production
From all the costs that are calculated above, with 400,000 lb/day or 14.3 MM gal/day of fresh
water produce, the variables cost per gallon fresh water production is shown in table below
$/year $/gal of Water
Utilities $ 11,892,235.16 $ 0.83
Depreciation $ 74,892.38 $ 0.01
Labor $ 1,560,000.00 $ 0.11
Maintenance $ 44,054.34 $ 0.00
Fixed Charge $ 86,749.03 $ 0.01
Total $ 13,657,930.92 $ 0.95
Table 11: Variables cost per gallon fresh water production
From the table above, the cost of utilities is the highest cost that need to spend for the process.
5) Cash Flow and NPV Analysis
A cash flow analysis is done based on Annual Depreciation, Variables Cost of Production,
Annual Labor, Maintenance, and Fixed Charges for this project with the total is equal $17MM
each year. Net Present Value (NPV) method is applied to assess the economic value of the
project. A common Internal Rate of Return (IRR) of 8.5% is used for calculation. Tax is
incorporated and equals 28% of the net income. Desalinated water is sold for $1/gal. 400,000
lb/year or 14.3MM gal/year of fresh water is produced. It means the revenue of this project
equals $14.3 MM. The NPV of this plant is calculated in 10 years.
Year Cost Revenue Tax Cash Flow NPV Total NPV to year
0 $ 881,086.84 $ (881,086.84) $ (881,086.84) $ (881,086.84)

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1 $ 13,657,930.92 $ 14,392,090.56 $ 205,564.70 $ 528,594.94 $ 449,305.70 $ (431,781.14)
2 $ 13,657,930.92 $ 14,392,090.56 $ 205,564.70 $ 528,594.94 $ 381,909.85 $ (49,871.30)
3 $ 13,657,930.92 $ 14,392,090.56 $ 205,564.70 $ 528,594.94 $ 324,623.37 $ 274,752.07
4 $ 13,657,930.92 $ 14,392,090.56 $ 205,564.70 $ 528,594.94 $ 275,929.86 $ 550,681.93
5 $ 13,657,930.92 $ 14,392,090.56 $ 205,564.70 $ 528,594.94 $ 234,540.38 $ 785,222.32
6 $ 13,657,930.92 $ 14,392,090.56 $ 205,564.70 $ 528,594.94 $ 199,359.33 $ 984,581.64
7 $ 13,657,930.92 $ 14,392,090.56 $ 205,564.70 $ 528,594.94 $ 169,455.43 $ 1,154,037.07
8 $ 13,657,930.92 $ 14,392,090.56 $ 205,564.70 $ 528,594.94 $ 144,037.11 $ 1,298,074.18
9 $ 13,657,930.92 $ 14,392,090.56 $ 205,564.70 $ 528,594.94 $ 122,431.55 $ 1,420,505.73
10 $ 13,657,930.92 $ 14,392,090.56 $ 205,564.70 $ 528,594.94 $ 104,066.81 $ 1,524,572.55
Table 12: Cash Flow and NPV Analysis
The NPV of this plant after 10 years is $1.5MM. The payback period is 2 years; the profit being
earned on the third year. With the NPV equal $1.5MM, which is 1.7 of the capital investment,
this project is worth implementing.
PROCESS WITH FOUR EFFECTS EVAPORATOR SYSTEM
A. Mass and Energy Balance
With pressure of the boiler P = 40 bar, pressure of the 1st effect P = 30 bar, pressure of the 2nd
effect P = 20 bar, pressure of the 3rd effect P = 10 bar, pressure of the 4th effect P = 4 bar, and
pressure of the condenser P = 1 bar, the base is given for mass flowrate of fresh water is 400,000
lb/day and is produced from sea water that contains 3.5 wt% salt, from the steam tables combine
with mass and energy balance equations, the mass of steam and brine coming out of each effect,
mass of cooling water coming in to the condenser, mass of steam needed to heat up in the boiler,
the heat duty of natural gas that is required to heat up the steam in the boiler, the heat duty of
condenser and its area need to design to cool the hot stream are calculated.

19. 19

20. 20
Figure 12: Mass and Energy Balance Calculation for four Effects Evaporator System
Based on the values are calculated, the summary for mass and energy balance for the system is
shown in these figures below
Figure 13: Mass Balance of the Process with four Effects Evaporator System

21. 21
Figure 14: Energy Balance of the Boiler and four Effects Evaporator System
Figure 15: Mass and Energy Balance of Condenser for four Effects Evaporator System

22. 22
From those values of mass flowrate and heat duty that are calculated above, the unit such as
power of the pumps or area of evaporators are find out to estimate for equipment cost of the
project.
B. Major Equipment List and Purchased Cost
Figure 16: Cost Equipment Calculation for four Effects Evaporator System
From those calculations that are presented above, the table of total equipment cost of process
is show in below
Name Unit of Size Value a b n Material Cost in 2010 Cost in 2016
Boiler Steam (liters/s) 3552.11 124000 10 1 Carbon Steel $ 159,521.07 $ 191,425.29
Condenser Area (m2) 19.36 1900 2500 1 Carbon Steel $ 50,293.17 $ 60,351.81
Effect 1 Area (m2) 15.17 330 36000 0.55 Carbon Steel $ 160,937.50 $ 193,125.00

23. 23
Effect 2 Area (m2) 14.29 330 36000 0.55 Carbon Steel $ 155,794.81 $ 186,953.77
Effect 3 Area (m2) 11.05 330 36000 0.55 Carbon Steel $ 135,244.07 $ 162,292.88
Effect 4 Area (m2) 9.93 330 36000 0.55 Carbon Steel $ 127,565.84 $ 153,079.01
Feed Pump Flow (liter/s) 2.12 8000 240 0.9 Carbon Steel $ 8,471.31 $ 10,165.57
Pump 1 Flow (liter/s) 1.20 800 240 0.9 Carbon Steel $ 8,282.97 $ 9,939.56
Pump 2 Flow (liter/s) 0.79 800 240 0.9 Carbon Steel $ 8,194.46 $ 9,833.35
Pump 3 Flow (liter/s) 0.53 800 240 0.9 Carbon Steel $ 8,135.62 $ 9,762.74
Pump 4 Flow (liter/s) 0.50 800 240 0.9 Carbon Steel $ 8,128.77 $ 9,754.52
Total Equipment Cost $ 996,683.49
Table 13: Total Equipment Cost for four Effects Evaporator System
The total equipment cost for the process system with four effects evaporator system equals
$996,683.49
C. Project Economics
1) 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 10 years.
Table 14: Annual Depreciation for four Effects Evaporator System
Annual depreciation for four effect evaporator system is $84,719.28
2) 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, electricity is used for the feed pump of sea water, and natural
gas is used for the boiler to heat water the run the system.
Utilities Consumption/day Cost $/unit Cost $/day Cost $/year
Cooling water (gal) 821,680.70 0.005 4,108.40 1,232,521.05
Total Equipment Cost $ 996,697.45
Salvage Value $ 149,504.62
Depreciable Asset Cost $ 847,192.84
Depreciation Rate/Year 10%
Annual Depreciation $ 84,719.28

24. 24
Electricity (kWh) 731,531.69 0.046 33,891.90 10,167,570.51
Natural – gas (MM BTU) 269.04 2.178 585.97 175,790.74
Total variables cost $/year 11,575,882.30
Table 15: Variables Cost of Production for four Effects Evaporator System
From the table above, the main costs that effect to the variables cost of production are cost of
cooling water for the condenser and cost of electricity for the sea water feed pump. However,
based on mass balance, to produce 400,000 lb/day of fresh water, the flowrate of sea water is
414,508 lb/day, which is 2.12 liters/s, and this value is constant, so the electricity cost is
constant; therefore, the main utilities that effects to the changing variables cost of production is
volume flowrate of cooling water.
3) 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 15% of the installed cost of the evaporators
Number of operators/shift 5
Operator salary $/hr 15
Number of engineers 2
Engineer Salary/season 25000
Plant Manager 1
Manager salary/season 37000
Over head 100% labor cost
Total labor cost $/year $ 1,560,000.00
Maintenance (5% Total equipment cost/year) $ 44,054.34
Fixed Charge ( 15% installed evaporator cost) $ 86,749.03
Table 16: Annual Labor, Maintenance, and Fixed Charges
4) Variables cost per gallon fresh water production
From all the costs that are calculated above, with 400,000 lb/day or 14.3 MM gal/day of fresh
water produce, the variables cost per gallon fresh water production is shown in table below

25. 25
$/year $/gal of Water
Utilities $ 11,892,235.16 $ 0.83
Depreciation $ 74,892.38 $ 0.01
Labor $ 1,560,000.00 $ 0.11
Maintenance $ 44,054.34 $ 0.00
Fixed Charge $ 86,749.03 $ 0.01
Total $ 13,657,930.92 $ 0.95
Table 17: Variables cost per gallon fresh water production
From the table above, the cost of utilities is the highest cost that need to spend for the process.
5) Cash Flow and NPV Analysis
A cash flow analysis is done based on Annual Depreciation, Variables Cost of Production,
Annual Labor, Maintenance, and Fixed Charges for this project with the total is equal $17MM
each year. Net Present Value (NPV) method is applied to assess the economic value of the
project. A common Internal Rate of Return (IRR) of 8.5% is used for calculation. Tax is
incorporated and equals 28% of the net income. Desalinated water is sold for $1/gal. 400,000
lb/year or 14.3MM gal/year of fresh water is produced. It means the revenue of this project
equals $14.3 MM. The NPV of this plant is calculated in 10 years.
Year Cost Revenue Tax Cash Flow NPV Total NPVto year
0 $ 996,683.49 $ (996,683.49) $ (996,683.49) $ (996,683.49)
1 $ 13,590,755.37 $ 14,392,090.56 $ 224,373.85 $ 576,961.34 $ 490,417.14 $ (506,266.36)
2 $ 13,590,755.37 $ 14,392,090.56 $ 224,373.85 $ 576,961.34 $ 416,854.57 $ (89,411.79)
3 $ 13,590,755.37 $ 14,392,090.56 $ 224,373.85 $ 576,961.34 $ 354,326.38 $ 264,914.59
4 $ 13,590,755.37 $ 14,392,090.56 $ 224,373.85 $ 576,961.34 $ 301,177.42 $ 566,092.01
5 $ 13,590,755.37 $ 14,392,090.56 $ 224,373.85 $ 576,961.34 $ 256,000.81 $ 822,092.82
6 $ 13,590,755.37 $ 14,392,090.56 $ 224,373.85 $ 576,961.34 $ 217,600.69 $ 1,039,693.51
7 $ 13,590,755.37 $ 14,392,090.56 $ 224,373.85 $ 576,961.34 $ 184,960.59 $ 1,224,654.10
8 $ 13,590,755.37 $ 14,392,090.56 $ 224,373.85 $ 576,961.34 $ 157,216.50 $ 1,381,870.60
9 $ 13,590,755.37 $ 14,392,090.56 $ 224,373.85 $ 576,961.34 $ 133,634.02 $ 1,515,504.62
10 $ 13,590,755.37 $ 14,392,090.56 $ 224,373.85 $ 576,961.34 $ 113,588.92 $ 1,629,093.54
Table 18: Cash Flow and NPV Analysis

26. 26
The NPV of this plant after 10 years is $1.63MM. The payback period is 2 years; the profit being
earned on the third year. With the NPV equal $1.63MM, which is 1.63 of the capital investment,
this project is worth implementing.
PROCESS WITH SIX EFFECTS EVAPORATOR SYSTEM
A. Mass and Energy Balance
With pressure of the boiler P = 40 bar, pressure of the 1st effect P = 30 bar, pressure of the 2nd
effect P = 25 bar, pressure of the 3rd effect P = 20 bar, pressure of the 4th effect P = 15 bar,
pressure of the 5th effect P = 10 bar, pressure of the 6th effect P = 4 bar, and pressure of the
condenser P = 1 bar, the base is given for mass flowrate of fresh water is 400,000 lb/day and is
produced from sea water that contains 3.5 wt% salt, from the steam tables combine with mass
and energy balance equations, the mass of steam and brine coming out of each effect, mass of
cooling water coming in to the condenser, mass of steam needed to heat up in the boiler, the heat
duty of natural gas that is required to heat up the steam in the boiler, the heat duty of condenser
and its area need to design to cool the hot stream are calculated.

27. 27

28. 28
Figure 17: Mass and Energy Balance Calculation for six Effects Evaporator System
From those values of mass flowrate and heat duty that are calculated above, the unit such as
power of the pumps or area of evaporators are find out to estimate for equipment cost of the
project.
B. Major Equipment List and Purchased Cost

29. 29
Figure 18: Cost Equipment Calculation for six Effects Evaporator System
From those calculations that are presented above, the table of total equipment cost of process
is show in below
Name Unit of Size Value a b n Material Cost in 2010 Cost in 2016
Boiler Steam(liters/s) 2969.32 124000 10 1 Carbon Steel $ 153,693.15 $ 184,431.78
Condenser Area (m2) 7.09 1900 2500 1 Carbon Steel $ 19,630.07 $ 23,556.09
Effect 1 Area (m2) 12.63 330 36000 0.55 Carbon Steel $ 145,565.34 $ 174,678.41
Effect 2 Area (m2) 12.73 330 36000 0.55 Carbon Steel $ 146,190.10 $ 175,428.12
Effect 3 Area (m2) 10.48 330 36000 0.55 Carbon Steel $ 131,398.89 $ 157,678.67
Effect 4 Area (m2) 7.37 330 36000 0.55 Carbon Steel $ 108,323.70 $ 129,988.44

30. 30
Effect 5 Area (m2) 6.8143 330 36000 0.55 Carbon Steel $ 103,769.04 $ 124,522.85
Effect 6 Area (m2) 4.3441 330 36000 0.55 Carbon Steel $ 81,081.04 $ 97,297.25
Feed Pump Flow (liter/s) 2.12 8000 240 0.9 Carbon Steel $ 8,471.31 $ 10,165.57
Pump 1 Flow (liter/s) 1.00 800 240 0.9 Carbon Steel $ 8,240.82 $ 9,888.98
Pump 2 Flow (liter/s) 52.75 800 240 0.9 Carbon Steel $ 16,515.52 $ 19,818.62
Pump 3 Flow (liter/s) 48.92 800 240 0.9 Carbon Steel $ 15,957.56 $ 19,149.08
Pump 4 Flow (liter/s) 48.26 800 240 0.9 Carbon Steel $ 15,859.62 $ 19,031.54
Pump 5 Flow (liter/s) 47.32 800 240 0.9 Carbon Steel $ 8,522.38 $ 10,226.86
Pump 6 Flow (liter/s) 85.88 800 240 0.9 Carbon Steel $ 14,004.62 $ 16,805.54
Total Equipment Cost $ 1,172,667.79
Table 19: Total Equipment Cost for six Effects Evaporator System
The total equipment cost for the process system with six effects evaporator system equals
$1.172MM
C. Project Economics
1) 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 10 years.
Table 20: Annual Depreciation for six Effects Evaporator System
Annual depreciation for six effect evaporator system is $99,676.76
2) 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, electricity is used for the feed pump of sea water, and natural
gas is used for the boiler to heat water the run the system.
Utilities Consumption/day Cost $/unit Cost $/day Cost $/year
Total Equipment Cost $ 1,172,667.79
Salvage Value $ 175,900.17
Depreciable Asset Cost $ 996,767.62
Depreciation Rate/Year 10%
Annual Depreciation $ 99,676.76

31. 31
Cooling water (gal) 312,683.35 0.005 1,563.42 469,025.03
Electricity (kWh) 731,531.69 0.046 33,650.46 10,095,137.39
Natural - gas (MM BTU) 225.43 2.178 491.00 147,299.22
Total variable cost $/year 10,711,461.64
Table 21: Variables Cost of Production for six Effects Evaporator System
From the table above, the main costs that effect to the variables cost of production are cost of
cooling water for the condenser and cost of electricity for the sea water feed pump. However,
based on mass balance, to produce 400,000 lb/day of fresh water, the flowrate of sea water is
414,508 lb/day, which is 2.12 liters/s, and this value is constant, so the electricity cost is
constant; therefore, the main utilities that effects to the changing variables cost of production is
volume flowrate of cooling water.
3) 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 15% of the installed cost of the evaporators
Number of operators/shift 7
Operator salary $/hr 15
Number of engineers 2
Engineer Salary/season 25000
Plant Manager 1
Manager salary/season 37000
Over head 100% labor cost
Total labor cost $/year $ 2,208,000.00
Maintenance (5% Total equipment cost/year) $ 58,633.39
Fixed Charge ( 15% installed evaporator cost) $ 128,939.06
Table 22: Annual Labor, Maintenance, and Fixed Charges
4) Variables cost per gallon fresh water production
From all the costs that are calculated above, with 400,000 lb/day or 14.3 MM gal/day of fresh
water produce, the variables cost per gallon fresh water production is shown in table below

32. 32
$/year $/gal of Water
Utilities $ 10,711,461.64 $ 0.74
Depreciation $ 99,676.76 $ 0.01
Labor $ 2,208,000.00 $ 0.15
Maintenance $ 58,633.39 $ 0.00
Fixed Charge $ 128,939.06 $ 0.01
Total $ 13,206,710.85 $ 0.92
Table 23: Variables cost per gallon fresh water production
From the table above, the cost of utilities is the highest cost that need to spend for the process.
5) Cash Flow and NPV Analysis
A cash flow analysis is done based on Annual Depreciation, Variables Cost of Production,
Annual Labor, Maintenance, and Fixed Charges for this project with the total is equal $17MM
each year. Net Present Value (NPV) method is applied to assess the economic value of the
project. A common Internal Rate of Return (IRR) of 8.5% is used for calculation. Tax is
incorporated and equals 28% of the net income. Desalinated water is sold for $1/gal. 400,000
lb/year or 14.3MM gal/year of fresh water is produced. It means the revenue of this project
equals $14.3 MM. The NPV of this plant is calculated in 10 years.
Year Cost Revenue Tax Cash Flow NPV Total NPVto year
0 $ 1,172,667.79 $ (1,172,667.79) $ (1,172,667.79) $ (1,172,667.79)
1 $ 13,206,710.85 $ 14,392,090.56 $ 331,906.32 $ 853,473.39 $ 725,452.38 $ (447,215.40)
2 $ 13,206,710.85 $ 14,392,090.56 $ 331,906.32 $ 853,473.39 $ 616,634.53 $ 169,419.12
3 $ 13,206,710.85 $ 14,392,090.56 $ 331,906.32 $ 853,473.39 $ 524,139.35 $ 693,558.47
4 $ 13,206,710.85 $ 14,392,090.56 $ 331,906.32 $ 853,473.39 $ 445,518.45 $ 1,139,076.92
5 $ 13,206,710.85 $ 14,392,090.56 $ 331,906.32 $ 853,473.39 $ 378,690.68 $ 1,517,767.60
6 $ 13,206,710.85 $ 14,392,090.56 $ 331,906.32 $ 853,473.39 $ 321,887.08 $ 1,839,654.67
7 $ 13,206,710.85 $ 14,392,090.56 $ 331,906.32 $ 853,473.39 $ 273,604.02 $ 2,113,258.69
8 $ 13,206,710.85 $ 14,392,090.56 $ 331,906.32 $ 853,473.39 $ 232,563.41 $ 2,345,822.10
9 $ 13,206,710.85 $ 14,392,090.56 $ 331,906.32 $ 853,473.39 $ 197,678.90 $ 2,543,501.00
10 $ 13,206,710.85 $ 14,392,090.56 $ 331,906.32 $ 853,473.39 $ 168,027.07 $ 2,711,528.07
Table 24: Cash Flow and NPV Analysis

33. 33
The NPV of this plant after 10 years is $2.7MM. The payback period is 1 years; the profit being
earned on the 2nd year. With the NPV equal $2.7MM, which is 1.6 of the capital investment, this
project is worth implementing.
OPTIONS:
From all the analysis economics parts that show in table 6, 12, 18, and 24, the more number of
effects evaporator, the higher NPV for this plant. The relation between number of effects
evaporator and NPV is shown in the table and graph below.
Table 25: Number of Effect to total NPV to 10th year
Figure 19: Number of Effect to Total NPV to 10th year
From the table and the graph above, 6 effects evaporator system should be used to design the
plant because it gives the highest NPV value. Also, the main cost that need to spend that effect
$(12,000,000.00)
$(10,000,000.00)
$(8,000,000.00)
$(6,000,000.00)
$(4,000,000.00)
$(2,000,000.00)
$-
$2,000,000.00
$4,000,000.00
0 1 2 3 4 5 6 7
TotalNPVto10years
Number of Effect
# of Effecct Vs Total NPV
Number of Effect total NPV to 10th year
1 $ (10,299,230.22)
3 $ 1,524,572.55
4 $ 1,629,093.54
6 $ 2,711,528.07

34. 34
the most changing to the NPV value is the cost of volume flowrate of cooling water for the
condenser. It is show in table and graph below.
Cooling Water Flowrate (MM gal/day) NPV to 10th year ($)
3.95 $ (10,299,230.22)
1.06 $ 1,524,572.55
0.82 $ 1,629,093.54
0.31 $ 2,711,528.07
Table 26: Cooling Water Flowrate to Total NPV to 10th year
Figure 20: Cooling Water Flowrate (MM gal/day) to Total NPV to 10th year
The more effects evaporator, the less steam need to cool, so the less cooling water need to use in
condenser; therefore, the higher total NPV.
In conclude, system should be design with 6 effects evaporator.
SAFETY CONCERN
A. Overall Process
The chemicals involved in this process are sea water, and desalinated water. They are not
harmful so all the preventions for this plant are wearing protective gloves, safety goggles, and be
careful with the place that have hot steam.
1 effect
3 effects
4 effects
6 effects
$(12,000,000.00)
$(10,000,000.00)
$(8,000,000.00)
$(6,000,000.00)
$(4,000,000.00)
$(2,000,000.00)
$-
$2,000,000.00
$4,000,000.00
- 0.50 1.00 1.50 2.00 2.50 3.00 3.50 4.00 4.50
Cooling Water Vs Total NPV

35. 35
B. Hazard and Operability study (HAZOP)
HAZOP Table and figure below is used for Steam at Boiler and Cooling Water in Condenser
Incident Effects Recommendations Likelihood Severity Detection
Overall
Risk
STEAM OF BOILER
1
Reverse
Flow No steam in each effect
Check valves to prevent
back flow and place a flow
meter 1 10 3 30
2 No Flow No steam in each effect Place a flow meter 1 7 3 30
3 More Flow
Too much steam in each
effect
Place a flow meter and
pressure transmitter 3 7 3 63
4 Less Flow
Less steam in each effect,
so less fresh water produce
Place a flow meter and
pressure transmitter 3 5 3 27
5
High
Temperature Combust or over pressure
Place a Temperature
Transmitter 5 3 5 75
6
Low
Temperature
Less steam in each effect,
so less fresh water produce
Place a Temperature
Transmitter 3 3 3 27
7
High
Pressure Rupture steam tube
Place a pressure
transmitter 3 5 3 45
8
Low
Pressure Rupture steam tube
Place a pressure
transmitter 1 5 5 25
COOLING WATER OF CONDENSER
9
Reverse
Flow
Too hot of fresh water
out of condenser
Check valves to prevent
back flow and place a flow
meter 1 7 3 21
10 No Flow No fresh water condense Place a flow meter 1 5 3 15
11 More Flow
Over pressure and
cause rupture Place a flow meter 3 5 5 75
12 Less Flow
Temperature of Fresh
water would increase Place a flow meter 3 5 3 45
13
High
Temperature
Temperature of Fresh
water would increase
Place a Temperature
Transmitter 5 3 3 45
14
Low
Temperature
Temperature of Fresh
water would decrease
Place a Temperature
Transmitter 3 3 1 9
15
High
Pressure Rupture cooling water tube
Place a Pressure
Transmitter 3 5 3 45
16
Low
Pressure Rupture cooling water tube
Place a Pressure
Transmitter 1 5 3 15
Table 27: HAZOP for Steam at Boiler and Cooling Water in Condenser

36. 36
Figure 22: Boston square for Boiler and Condenser HAZOP
CONCLUSION and RECOMMENDATION:
This report is about a general plant design 400,000 lb/day of fresh water from sea water with 3.5
wt% salt. From all economics analysis, the system will have 1 boiler, 6 effects evaporator, 6
pumps and 1 condenser. The project requires $1.2 MM capital investment and annual $14.4 MM
cost for production. After 1 years, the investment starts to earn profit. At the end of year 10th,
NPV is about $2.7 MM. And the flowrate of cooling water is the most effective to changing
NPV value with the more effects evaporator, the less steam need to cool, so the less cooling
water need to use in condenser; therefore, the higher total NPV. And the recommendation for
this process is add the pressure transmitter, flowrate transmitter, and temperature transmitter in
each effect to guarantee the plant work well as its expectation.
1
2, 9 3
4, 7 11, 12 15
6, 14
8, 10, 16
0
2
4
6
8
10
12
0 2 4 6 8 10 12
Severity
Likelihood
Boston squarefor Boiler and Condenser HAZOP
5, 13

37. 37