Rabu, 27 September 2017

Jurnal seminar International di banda aceh 2015

Calculation Needs of Fuel Boiler Biomass Power Plant Oil
Sei Mangkei Capacity 2x3,5 MW

Indra Roza*,Noorly Evalina2)Dharmawati3)
Departemen Electrical Enggenering Sekolah Tinggi Teknik Harapan Medan
Jl.H.M. Joni No.70-c Medan

Palm Biomass power plantSeiMangkeiis an alternative electrical power source by converting energy of EFB (empty fruit bunches) and shell are used as fuel in steam generator. Common steam generators are called boilers produce pressure steam used to rotate of corners turbine. The amount of empty fruit bunches to be produce in Palm oil plantations based on the capacity. The capacity of palm oil plantation SeiMangkei is 75 tons/hour. Material balance = 21.96% empty fruit bunches is 22%, the combustion process is well if the fuel composition EFB: shell = 70: 30. The needs  fuel of shell is 5.8 tons per day and the need  fuel EFB is 5.4 tons per day .After having research the  need of  boiler  fuel in Normal Operation steam is 17.29 tons/hour or more excess of 8.40 tons of steam/hour. The needs of fuel boilers in abnormal operation steam required 17.29 tons of steam/hour or more 13.35 tons of steam/hour. In fact, duringthe factory operates, it doesn’t need an electricity supply from outside like PLN. EFB and shell as fuel Biomass power plant oil SeiMangkei generating produces energy 2 x 3.5 MW, the use can be economized so that shell is still left.
Key words: Calculation need of fuel, boiler, power plantSeiMangkei, Capacity 2x3.5 MW

I. Introduction
Based on statistical data of State Electrical Company (PLN) on 31 March 2007distributed fuel to generating until 34% of the total installed in generating capacity. The expensive fuel requires to PLN to review all thermal power plants that use oil as the main fuel steam generators. Beside that the amount of government subsidies to PLN in supplying electricity every yearmainly oil power plants. The subsidies are mostly used to reduce loss operating PLTU. The cause of loss is the difference of the fuel cost in kWh oandselling price (electricity tariff) to the consumer. Therefore, it is useful to change fuel so that the cost of electrical energy can be more economical.

Palm Biomass plants SeiListriskMangkeiis an alternative power which the power is required for operating of factory and society is obtained by converting the energy of additional product itself into electrical energy. Additional products are EFB and shell which is used as fuel in steam generator. Steam generator or commonly called a boiler produces steam that will be used to rotate the blades of the turbine. Turbine produces electricity for the operational needs of factory and outside such as streetlighting, housing, etc. So as long as the factory is operating, it doesn’t need electricity supply from outside like PLN or diesel generators.

EFB and shell as fuel for boiler is enough to produce steam to the pressure required by the turbine. Even the use can be saved. Boiler is a closed vessel in which the combustion heat transfers to water until steam formlike energy. Water is useful and easy to flow heat to a process, then steam and a certain temperature have a value of energy which is used to flow heat in the form of heat energy to a process.

II. Theoretical Framework
Electrical Steam Power Plant
Electrical steam power plant is a plant fromkinetic energy from steam to electric energy. The main form of this type of power plant is a generator which is connected to turbine where to turn turbines required kinetic energy of steam. Electrical steam power plants use a variety of fuels, especially coal and fuel oil.

2.2. Steam power comes from nuclear Power Process
Nuclear power plant is thermal power station where the heat is from one or more nuclear reactors in it (
There are one or more nuclear reactors in PLN. In nuclear reactors, nuclear reactions take place. The nuclear reaction produces high heat. This heat is used to produce electricity.

2.3 Geothermal Energycomes from Solar
Geothermal energy is thermal energy stored in the rocks under the earth's surface and the fluid. Geothermal energy has been used for power plant in Italy since 1913 and in New Zealand since 1958. The utilization of geothermal energy for non-electric sector (direct use) takes palce in Iceland around 70 years. The increasing needs for energy and rising oil prices, particularly in 1973 and 1979 has spurred other countries including the United States to reduce their dependence on oil by utilizing of geothermal energy. Nowdays geothermal energy has been used for power plants in 24 countries including Indonesia. Besides that the geothermal fluid is also used for non-power sector in 72 countriesfor space heating, water heating, greenhouse heating, drying of agricultural products, soil heating, drying wood, paper and so on.

2.3 Thermal Energy from Gas Combustion Process
PLTG (gas power plant) is a generator of electric energy using equipments/ gas turbine engine as a generator drive. Gas turbine is designed and made with a simple working principle where the thermal energy from the fuel combustion process is converted into mechanical energy and then converted into electrical energy or other energy according to the needs. The weakness of gas turbine is corrosive to material used for turbines components because it must work at high temperatures and there is chemical elements corrosive fuel (sulfur, vanadium, etc.), but in the development of knowledge evolving materials can be reduced although it can not be removed all. With a low level of efficiency this is also one of the weakness from gas turbine as well and the development to increase efficiency can be set at working temperature turbine cycle using the material that is able to work at high temperatures and also increase efficiency by combining the power turbine gas with steam turbine generator and it is commonly called by combined cycle.

2.4 Ocean Thermal Energy Conversion (OTEC)
Ocean Thermal Energy Conversion (OTEC) is a method to produce electrical energy using the difference temperature that lies between deep sea and near surface waters to run a heat engine. Commonly the heat engine and the largest energy are generated by the difference of large temperature. The difference temperature between deep sea and surface waters are generally greater if they are closer to the equator. At first, OTEC design challenge is to produce maximum energy with the smallest different temperature.

2.5 Heat (steam) comes from the process of Biomass Process Oil
Basically PLTBS is a PLTU which uses biomasspalm oil. From PLTBS’s scheme as shown in Figure 2.3 we can see that the EFB is passed to the shredder, in shredder TKS is shredded to obtain a piece of fiber with a maximum length about 100 mm. Then TKS is supplied by conveyor to oil presser. In oil presser water content is reduced to produce oil and fiber wadding. In dryer the moisture of EFB is reduced until 40%. Then TKS is collected in the silo before being fed into the combustion for heating boilers. Steam produced by boiler will be used to turn turbineswhich stemps directly with a generator and generator will rotate to produce electricity. After passing through the turbine, the steam pressure and high temperature comes into the condenser. The steam is condensed by the condenser into the water from the cooling becomes water which is pumped back to dearatorand then feeding to the boiler.

2.6. Rankine cycle
Rankine cycle (Figure 2.2) is the ideal cycle for steam power cycle. In the simple form of a Rankine cycle consists of four components, namely pumps, boilers, turbines and condensers.


Figure 2.6 Rankinecycle and graphs T (temperature) vs s (entropy)

Rankine cycle doesn’t consist of four stages of the process:
• 1-2 is an isentropic compression process with pump.
  2-3 Addition of heat in boiler at P = constant.
• 3-4 isentropic expansion into the turbine.
• 4-1 dissmissing of heat in the condenser at P = constant

Water enters the pump on the condition 1 as a saturated liquid and compressed to the operating pressure of boiler. Water temperatures will rise during this isentropic compression through a simple reduction of water specific volume.

The water enters boiler as a compressed liquid in conditions 2 and will become superheated steam on condition 3. The Heat supplies boiler to water at T (temperature) permanently. Boilers and all parts are called by steam generators.

Superheated steam in conditions 3 will be entered turbine to be expanded and generate workingto rotate shafts and it will be connected to the electric power generator so that it will produce electricity. P (pressure) and T (temperature) of steam will be down during this process towards condition 4 where the steam will enter condenser and usually in the form of saturated steam. This steam will be meltedto P constant in the condenser and it will leave the condenser as saturated liquid to enter the pump to complete this cycle.
Data under the process of curve on the diagram T - s (entropy) shows that transferrigheat  to the internal reversible process. An area under the curve of the process 2-3 shows transferring heat to boiler, and the area under the curve 4-1 shows the heat releases in the condenser. Differences between these flows are netto working produced during the cycle.

2.7 Energy Cycle of Power Engine
In PLTU, energy is a thermal energy produced from the burning of fossil fuels/conventional. The thermalenergy  is used toheat boiler and generate steam pressure and high temperature. Thermal energy is converted into mechanical energy which drive/rotate a generator, changing thermal energy into mechanical and electrical energy through an energy conversion cycle which dependents on the amount of heat, the temperature pattern and environment temperature or the temperature of heat receiver (boiler). A heat cycle receives a number of thermal energy in a certain temperature, and change a part of thermal energy into working, discard or forwards the rest to the environment or heat receiver as "loss energy" at a lower temperature (in this case it can be seen in the function of condenser). Figure 2.1 shows a general heat cycle on temperature and entropy coordinates. Large 1-2-ba is the amount of thermal energy at a temperature T1 which is accepted by the working medium at temperature T2.  Large 1-2-3-4 is useful energy. This cycle is known as the Carnot cycle whis is ideal cycle, where the condition can’t find thermal efficiency of the engine

According to Carnot cycle
= 1
Where :
 = Temperature of Energy source, (K) and
                 = Temperature of receiver energy (K).





         Figure 2.4. (a) Ideal heat Carnot cycle

In reality energy cycle is shown in Figure 3.1 (b). T1 temperature is not constant like Figure 3.1 (a), but 1-2 is uneven curve. And T2 temperature rises of 3-4 into 3'-4 ', and the amount of wasting energy bases on the large 3'-4'-ab, which is larger than the 3-4-ab.

Figure 2.5. (b)  Heat realistic Carnot cycle

In a PLTU In order to be high efficiency,  the ratio T2 / T1 should be as small as possible. Temperature T2 is the temperature of 303 K. The temperature of the environment eg T1 is the temperature of the steam, for example 600 ° C or 873 K. The efficiency of the engine thus becomes 1- 303/873 = 0.6529 or 65.39%.  It is difficult to improve efficiency, because the temperature of environment is a fact, while raising the temperature of the steam will knock on the durability of the material. In the energy cycle is very important to look at types of energy sources used to generate heat, steam cycle, the use of machine such as steam boilers, and meedium heat receiver with the lowest temperature (condenser).

III. Research Methodology
Palm oil factory produces three types of solid wastes such as fiber, shell and EFB (empty fruit bunches), other products from solid wastes are the result of fuel combustion. Utilization of biomass waste at this time is to fulfill the palm oil processing energy through direct combustion of fiber and shells. MeanwhileEFB and the rest of combutions are used as fertilizer in the farm to reduce the consumption of chemical fertilizers and maintain climatic conditions  of palm tree.
Shells and fibers contain the value of calory relatively high as shown in Table 3.2 that can be used as fuel PLTBS.

Tabel 3.1 Composition of palm oil calory
Parts of Palm oil
Heating Value
4,105 – 4.802 kcal/kg
2.637 – 4.554 kcal/kg
4.492 kcal/kg
4.176 kcal/kg
4.695 – 8.569 kcal/
Note : 1 kcal = 4187 Joule = 1,163 Wh
Note : POME = Palm Oil Mill Effluent
(TabelSource : PT. PalsihokUtama Team, An intermediate report biomassa& biogas power plant at Blankahan palm oil mill)

Figure3.1Schematic of Biomassa Power Plant Oil (PLTBS)

At this time the biggest user of fuel oil is for power generation purposes. The biggest PTPN in Kalimantan, Sulawesi and Sumatra are sources of potential biomass generate electrical energy which hasn’t been managed effectively.

Table  3.2The potential energy produced by PTPN I–PTPN VII

Total Installed Capacity(Ton/Hour)
Potential (MW)

Note       : Not all potentials MCC are used to PLTBS,
  becauseparts of compost are composted
Source    : -  BBN BUMN tim (2007)bioenergy
     developmentBUMN program, Jakarta.
  - Muluk at al (2007), Workshop on
     Dissemination of Biofuel BUMN, Jakarta

Table 3.3 Potential Biomass PTPN III
TBS (Kg)
Own Farm
Plasma farm and  party III

Table 3.4 Potential Biomass becomes electrical energy PTPN III
EFB (Kg), 22%
Kolor value Kcal/Kg
Steam (ton)
Own Farm
Plasma farm P-III

Shell (Kg), 6%
Kolor Value Kcal/Kg
Steam (ton)
Own Farm
Plasma Farm and P-III

Fiber (Kg), 14%
Kolor Value Kcal/Kg
Steam (ton)
Own Farm
Plasma Farm and P-III

71.21 MW/h

         Gambar3.2 Biomass Power plant Cycle

IV. Results and Discussion
Fiber EFB of palm oil plantation (PKS) 1 and 2 are sent by using the conveyor to PLTBS area. It reminds that  unequalsupply of EFB between PKS 1 and 2, EFB is placed temporary in hopper (accumulator) in order to supply EFB to the next  constant process and adjustable speed. Accumulator has a capacity of 60 m3.
The following diagram is material balance of TBS:

From the diagram of TBS material balance can be known amount EFB to be produced in PKS based on the capacity. For the capactity of PKS SeiMangkei capacity installed is 75 tons/hour. Material balance is 21.96% EFB ≈ 22%, it can be calculated the number of EFB is as follows:
The number of EFB            = 22% x 75 ton/hour
                                                = 16,5 ton/hour

Tabel 4.1 The compotion of EFB and shell feed boiler
( % )
( % )
( Kg /M3 )
Catatan :-Moisture is the value of moisture contant
                 -Density is the value of density

From the data above data, it can be calculated fuel supplywithout EFB or 100% shell is as follows:
-          Capacity of shell silo          = 250 m3
-          Density shell (ρ)                   = 574,71 Kg/m3
-          Shells need            = 5,4 ton/hour
The amount of weight of shell silo
                = 250 m3 x 574,71 Kg/m3
= 143677,5 Kg ≈ 143,7 ton

The need of shell in 1 day
= 5,4 ton/hour x 24 hours
= 129,6 ton/days

The amount of shell silo 2 unit                        
= 2 x 143,7 ton
= 287,4 ton

Shell supply
= 2,2 days or 2 days 5 hours
Tabel 4.1.the need of Shell fuel
Shell (cangkang)
5,4 ton/hour
129,6 ton/day
3888 ton/month

The amount use of EFB in 1 day is:
-          The need of EFB                 = 5,8 ton/hour
-          Density (ρ)                            = 320 Kg/m3
-          Capacity of accumulator  = 60 m3

The need of EFB in 1 aday
                = 5,8 ton/hour x 24 hours
                = 139,2 ton/day

The amount of weight accumulator  :            
= 60 m3 x 320 Kg/m3
                 = 19700 kg or 19,7 ton

The supply of EFB in  accumulator :                               =
                                = 3 hours 24 minutes

Tabel 4.2. The need of  EFB  fuel
5,8 ton/hour
139,2 ton/day
4176 ton/month

Comparison need of shell and EFB fuel can be shown  in figure 4.2.


Gambar 4.2.the comparison of fuel need shell (a) and  EFB  (b)
From description above Figure 4.2. (a) and (b) can be concluded that EFB  has the biggest need for fuel supply compared with shell. EFB fuel requires a supply of 4176 tons/ month, while shell fuel requires a supply of 3888 tons/month.
To maintain a supply of good fuel boiler and shells keep going in time to maintenance or repair of equipment when processing does not exceed from the maximum of over calculation.

Calculation need of Fuel Boilers
1. The Needs Fuel Boilers In Normal Operation
Biomass Power Plant Oil (PLTBS) 2 X 3.5 MW in each unit requires a steam boiler as much as 4.94 kg per 1 kW per 1 hour generated.

Total steam required for 1 boiler:
                            = 3.500 Kw x 4,94 Kg/Kw/hour
                            = 17.290 Kg uap/hour
                            = 17,290 ton uap/hour

The fuel used is EFB70% dan shell 30% :
                     EFB = 5,8 ton/hour
                             = 5800 kg/hour
                     Shell= 2,5 ton/hour       
                             = 2500 kg/hour

Weight fuel:
                     = 5800 kg/hour + 2500 kg/hour
                     = 8300 kg/hour

Heating value fuel boiler can be explained as follow:
a.       Shell
      Heating Value Shell        =   4120 Kcal/kg
b.       EFB
      Heating value EFB          =   1440 Kcal/kg

Heating value above used for boiler in certain condition :
Pressure                                                 =   43 kg/cm2
Temperatur                                           =   4000C
Kettle Efficiency                                 =   90 %
Water vapor Temperature                 =   1100C
Water Pressure                                     = 48 Kg/cm2
Weight fuel                                           =   8300 Kg/hour

Entalphy in pressure.43 kg/,temp. 4000C                                              = 764,09 Kcal/Kg
Entalphy in water pressure. 48 kg/,temp. 1100C                                  = 110,69 Kcal/Kg
Entalphy= 764,09 Kcal/Kg – 110,69 Kcal/Kg
                = 653,40 Kcal/Kg

                                Q             =

                     Q        =

                                =  25691,46Kg steam/hour

=  25,69 ton steam/hour
Whil the steem needed is 17,29 ton steam/hour or`it takes palceaccess of 8,40 ton steam/hour. Combustion process is happening well if fuel compotitionEFB : shell = 70 : 30.

2. The Needs Fuel Boilers InAbnormal Operation
If the need for EFB can not be supplied by PKSSeiMangkei, the fuel Shell (Shells) is used entirely.
The fuel used is shell of 100%:

Shell                            = 5,4 ton/hour                            
                                      = 5400 kg/hour
Weight fuel                 = 5400 kg/hour

Heating valueof fuel boiler (shell 100%) can be explained as follow:

Heating Value Shell                           = 4120 Kcal/kg
Pressure                                                 =   43 kg/cm2
Temperature                                         =   4000C
Kettel Efficiency                                 =   90 %
Water Temperature                             =   1100C
Water Pressure                                     = 48 Kg/cm2
Heating value (N.O)                            =   4120 Kcal/Kg
Weith fuel                                             = 5400 Kg/hour

Entalphyin pressure.43 Kg/cm2,temp. 4000C                                               = 764,09 Kcal/Kg
Entalphy in water pressure. 48 Kg/cm2,temp. 1100C                                  = 110,69 Kcal/Kg
Entalphy = 764,09 Kcal/Kg – 110,69 Kcal/Kg
= 653,40 Kcal/Kg

     ηKete l =

     Q     =

    Q      =   
    Q   =  30644,62 Kg steam/hour

          = 30,64 ton steam/hour

The steam required is 17.29 tons of steam/hour or an excess of 13.35 tons of steam/hour.

V. Conclusions

1.     The amount of EFB which will be produced in PKSbased on  the capacity. For PKS Sei Mangkei, the capacity installed is 75 tons/hour. Material balance is 21.96% EFB ≈ 22%,
2.     The combustion process takes place well if the fuel composition is EFB: shell = 70: 30.
3.     The needs of Fuel Shell is 5.8 tons /day while demand Fuel EFB (tankos) 5.4 tons per day
4.  The needs of fuel boilers in normal operation, the steam required is 17.29 tons of steam/hour or an excess of 8.40 tons of steam/hour
5. The needs of fuel boilers in abnormal operation, steam required is 17.29 tons of steam / hour or an excess of 13.35 tons of steam / hour.

VI.      References

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