3.9 ENEGRY BALANCE

3.9.1 Power Balance

Due to the availability of oil palm biomass, palm oil mill itself is able to generate

electricity for domestic usage and manufacturing purpose. In the designed mill, mesocarp fiber

and palm shell are used as boiler fuel to generate steam. These two solid fuels alone are able to

generate more than enough energy to meet the energy demands of a palm oil mill. The steam

generated from boiler is sends to turbine for generating electricity. The exhaust steam is then

sends to back pressure vessel for production usage. The details power consumption of each

station with the total power generated from turbine in the designed palm oil mill is shown in next

section.

3.9.1.1 Power Consumption

The power consumption of each station is determined based on the equipment

specification. Additional 200 kWh is allocated for domestic usage including power usage in

POME treatment plant and raw water treatment plant. Table X shows the power consumption for

each station. The estimated total power consumption for a 30 ton FFB/hour palm oil mill is

1312.1 kWh.

Table X: Power Consumption for Each Station.

NO MACHINERY QUANTITY POWER (kWh) TOTAL POWER (kWh)

FRUIT RECEPTION

1. Road Weighbridge 2 30 60

2. Fruit Loading Ramp 1 5.6 5.6

STERILIZATION STATION

3. Tilting Sterilizer 2 23 46

THRESHING STATION

4. Thresher 2 50 100

DIGESTION STATION

5. Digester 3 33 99

6. Screw Press 3 29 87

CLARIFICATION STATION

7. Sand Trap Tank 1 4 4

8. Vibrating Screen Separator

2 2 4

9. Crude Oil Tank 1 4 4

10. Continuous Settling Tank

1 9 9

11. Hot Water Tank 1 4 4

12. Pure Oil Tank 1 4 4

13. Oil Purifier 2 7.5 15

14. Oil Holding Tank 1 4 4

15. Vacuum Oil Dryer 1 11 11

OIL STORAGE TANK

16. Oil Storage Tank 1 7.5 7.5

17. CPO Daily Storage Tank

2 7.5 15

SLUDGE SEPARATION STATION

18. Sludge Buffer Tank 1 4.5 4.5

19. Desander 1 11 11

20. Sludge Drain Tank 1 4.5 4.5

21. Rotary Brush Strainer 1 11 11

22. Sludge Separator 2 15 30

23. Sludge Oil Tank 1 4 4

DEPERICARPING STATION

24. Cake Breaker Conveyor

1 15 15

25. Depericarper Vertical Column

1 48 48

26. Nut Polishing Drum 1 7.5 7.5

27. Pneumatic Fiber Transport System

1 75 75

KERNEL STATION

28. Nut Silo 1 4 4

29. Ripple Mill 2 11 22

30. Claybath 1 85 85

31. Bulk Kernel Silo 1 4 4

32. Wet Shell Bunker 1 4 4

BOILER STATION

33. Boiler 1 35 35

POWER STATION

34. Fuel Tank 1 7.5 7.5

EFB STATION

35. EFB Shredder Machine

1 75 75

36. EFB Fiber Press 1 45 45

37. Hammer Mill Machine

1 56 56

38. Rotary Dryer 1 75 75

39. Baler Machine 1 60 60

DOMESTIC USAGE AND WATER TREATMENT PLANT

40. Office, Laboratory, Storage Room,

Workshop, POME Treatment Plant, Raw Water Treatment Plant

1 200 150

TOTAL POWER 1312.1

3.9.1.2 Power Generation

Steam turbine is using steam from boiler to generate electricity. The exhaust steam from

steam turbine will store in backpressure vessel for processing. Before running the boiler, diesel

generator is used to supply electricity for palm oil mill. The amount of power generated for the

designed mill is shown in Table X.

Table X: Power Generation.

Steam Turbine

Total Power Consumption = 1312.1 kWh

Output Power of Steam Turbine = 1500 kWh

Actual Output Power of Steam Turbine = 1500 kWh X 90% = 1350 kWh

Steam Required for Steam Turbine = 25 kg steam/kWh

Total Steam Required = 25 kg steam/kWh X 1500 kWh

= 37,500 kg Steam

Exhaust Steam for Processing = 37,500 kg Steam X 90% = 33,750 kg

Steam

Diesel Engine Set

Output Power per Engine Set = 450 kW

Total Diesel Engine Set Required = 3

3.9.1.3 Boiler Selection

Steam Boiler is any closed vessel in which for any purpose steam is generated under

pressure and include any economizer used to heat water being feed to the boiler and any super

heater used for heating steam and any pipes and fitting connected there to. Table X shows the

calculation of the required boiler plant for the designed mill.

Table X: Steam Boiler Selection.

Data

Mill Throughput = 30 ton FFB/hour

Raw Water Temperature = 27ºC

Boiler Feed Water = 80ºC

Boiler Safe Working Efficiency = 85%

Steam Required for Turbine = 37,500 kg Steam/hour

Boiler Steam Capacity Capabilities = 45 ton of Steam/hour X 0.85

= 38.25 ton of Steam/ Hour

From the above calculation, the mill needs 37.5 ton of Steam/hour for steam turbine to

generate electricity. But in term of long term planning, the mill was installed boiler with capacity

of 45 tons steam/ hour. The working pressure of boiler is 22 bar with processing temperature of

260ºC.

3.9.1.4 Fuel Availability

For this mill, EFB will not be used as boiler fuel as it will further processed to become

value added by product. The fuel source for boiler is mainly for mesocarp fiber and palm shell.

The calorific value of mesocarp fiber and palm shell is 19,000 kJ/kg and 18,836 kJ/kg

respectively. The amount of boiler fuel required is calculated as shown in Table X.

Table X: Boiler Fuel.

Data

Amount of Palm Shell = 30 ton FFB/hour X 5.2% = 1,560 kg shell/hour

Calorie Value of Palm Shell = 19,000 kJ/kg

Amount of Mesocarp Fiber = 30 ton FFB/hour X 19.25% = 5,775 kg fiber/hour

Calorie Value of Mesocarp Fiber = 18,836 kJ/kg

Heat Required to Heat 1 kg of Steam at 22 bar in Boiler

From Steam Table

At 22 bar, hf = 930.562 kJ/kg & hfg = 1869.4 kJ/kg

Let assume steam is 0.9 dry, x = 0.9

h = hf + xhfg

h = 930.562 kJ/kg + [0.9 X 1869.4 kJ/kg]

h = 2613.022 kJ/kg

Heat Already Present in Water

Q = cp X T

Q = 4.187 kJ/kg. ºC X 80ºC

Q= 334.96 kJ/kg

Heat Required to Generate 1 kg of Steam

h = 2613.022 kJ/kg - 334.96 kJ/kg

h = 2278.062 kJ/kg

Steam Required For Boiler = 38.25 ton of Steam/hour

Heat Required to Generate Steam = 38,250 kg of Steam/hour X 2278.062 kJ/kg.kg Steam

= 8.71 X 107 kJ/kg.hour

Amount of Fuel Required to Generate Steam

Palm Shell

Let assume heating efficiency of 70%

h = 1,560 kg shell/hour X 19,000 kJ/kg X 0.7

h = 2.075 X 107 kJ/kg.hour

Mesocarp Fiber

Let assume heating efficiency of 70%

h = 5,775 kg shell/hour X 18,836 kJ/kg X 0.7

h = 1.08 X 108 kJ/kg.hour

Total Heat Generated

h = 2.075 X 107 kJ/kg.hour + 1.08 X 107 kJ/kg.hour = 1.288 X 108 kJ/kg.hour

From the above calculation, burning of palm shell and mesocarp fiber is enough to

generate sufficient steam for processing of CPO.

3.9.1.5 Summary of Power Balance

Table X: Overall Power Balance.

Power Generation Power Consumption Power Loss

1350 kWh 1312.1 kWh 37.9 kWH

Steam Generated Remaining Steam Steam Loss

38,250 kg/hour 33,750 kg/hour 4500 kg/hour