Energy Balance

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. N

MACHINERY

QUANTITY

O FRUIT RECEPTION 1. Road Weighbridge 2. Fruit Loading Ramp STERILIZATION STATION 3. Tilting Sterilizer THRESHING STATION 4. Thresher DIGESTION STATION 5. Digester 6. Screw Press CLARIFICATION STATION 7. Sand Trap Tank 8. Vibrating Screen

POWER (kWh)

TOTAL POWER (kWh)

2 1

30 5.6

60 5.6

2

23

46

2

50

100

3 3

33 29

99 87

1 2

4 2

4 4

Separator 9. Crude Oil Tank 1 10. Continuous Settling 1 Tank 11. Hot Water Tank 1 12. Pure Oil Tank 1 13. Oil Purifier 2 14. Oil Holding Tank 1 15. Vacuum Oil Dryer 1 OIL STORAGE TANK 16. Oil Storage Tank 1 17. CPO Daily Storage 2 Tank SLUDGE SEPARATION STATION 18. Sludge Buffer Tank 1 19. Desander 1 20. Sludge Drain Tank 1 21. Rotary Brush Strainer 1 22. Sludge Separator 2 23. Sludge Oil Tank 1 DEPERICARPING STATION 24. Cake Breaker 1 Conveyor 25. Depericarper Vertical 1 Column 26. Nut Polishing Drum 1 27. Pneumatic Fiber 1 Transport System KERNEL STATION 28. Nut Silo 1 29. Ripple Mill 2 30. Claybath 1 31. Bulk Kernel Silo 1 32. Wet Shell Bunker 1 BOILER STATION 33. Boiler 1 POWER STATION 34. Fuel Tank 1 EFB STATION 35. EFB Shredder 1 Machine 36. EFB Fiber Press 1 37. Hammer Mill 1 Machine

4 9

4 9

4 4 7.5 4 11

4 4 15 4 11

7.5 7.5

7.5 15

4.5 11 4.5 11 15 4

4.5 11 4.5 11 30 4

15

15

48

48

7.5 75

7.5 75

4 11 85 4 4

4 22 85 4 4

35

35

7.5

7.5

75

75

45 56

45 56

38. Rotary Dryer 1 75 39. Baler Machine 1 60 DOMESTIC USAGE AND WATER TREATMENT PLANT 40. Office, Laboratory, 1 200 Storage Room, Workshop, POME Treatment Plant, Raw Water Treatment Plant TOTAL POWER

75 60 150

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 Output Power of Steam Turbine Actual Output Power of Steam Turbine Steam Required for Steam Turbine Total Steam Required



Exhaust Steam for Processing

= 1312.1 kWh = 1500 kWh = 1500 kWh X 90% = 1350 kWh = 25 kg steam/kWh = 25 kg steam/kWh X 1500 kWh = 37,500 kg Steam = 37,500 kg Steam X 90% = 33,750 kg Steam

Diesel Engine Set  

Output Power per Engine Set Total Diesel Engine Set Required

= 450 kW =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  Raw Water Temperature  Boiler Feed Water  Boiler Safe Working Efficiency Steam Required for Turbine Boiler Steam Capacity Capabilities

= 30 ton FFB/hour = 27ºC = 80ºC = 85% = 37,500 kg Steam/hour = 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 1350 kWh Steam Generated 38,250 kg/hour

Power Consumption 1312.1 kWh Remaining Steam 33,750 kg/hour

Power Loss 37.9 kWH Steam Loss 4500 kg/hour