Inthis project Exergy Analysis of Al-Hussein Power Plant in Jordan is studied. All the systemcomponents are analyzed separately to know the sites having the largest exergylosses.
In addition, the effect of changing the dead state or referenceenvironment temperaure is observed. The performance of the plant was shownby a component wise modeling and a step by step break-up of exergy losses forthe considered plant.The maximum exergy relative to the total exergy wasdestroyed in the Boiler (77%)followed by the Turbine (13%), andthen the Forced Draft Fan Condenser (9%).
In addition, the calculated Thermal Efficiency based on the Lower Heating Value (LHV or NCV) of fuel was 26% while the Exergy Efficiencyof the power cycle was 25%. As the reference environment state temperature waschanged slightly, there were no noticeable changes in the performance of majorcomponents and the main conclusion remained the same; the boiler is the major sourceof irreversibilities in the power plant. It is seen that chemical reaction isthe most important source of exergy destruction in a boiler system but it canbe cured by preheating the combustion air and decreasing the air–fuel ratio.
IntroductionJordan’s energy market is growing at tremendous rates. Annualdemand for electricity has increased by more than 9% during recent years, andinstalled capacity and annual generation figures have reached 9000 GW h in 20061. CentralElectricity Generating Company (CEGCO) is the only power generating companyin the country using heavy fuel oil, diesel, gas, and renewable resources. Thepower plants are spread in many Jordanian cities, which are transmitting power throughoverhead lines of 132 and 400 kV. Analysis of power generation systems are of scientific interest andalso essential for the efficient utilization of energy resources.
The analysisof energy-conservation process is widely done using the first law ofthermodynamics. However, there is a growing interest in the combined utilizationof the first and second laws of thermodynamics, using the concepts of Exergy and Exergy Destruction in order to evaluate the efficiency with whichthe available energy is consumed. Exergetic analysis enables us todifferentiate between energy losses to the environment and internalirreversibilities in the process2.Exergy analysis is a method for the evaluation of the performance ofdifferent devices and processes, and it involves considering the exergy atdifferent states in a series of energy-conversion steps. Using thisinformation, we can evaluate the efficiencies of different components and theprocess steps having the greatest losses can be identified3. These are the reasons why the exergy analysis is used to analyse aprocess in modern times, which provides a more realistic view of the processand a useful tool for engineering evaluation4.
Nowadays researchers5-8 also recommend the use of exergy analysis to aid decision makingregarding the distribution of resources (i.e.capital, research and developmenteffort, optimization, life cycle analysis, materials, etc.
) instead of onlyenergy analysis3. Exergy analysis has become an important aspect inproviding a clear understanding of the process, to quantify sources of inefficiency,and to identify the quality of energy used9. Some researchers focused their studies to component exergyanalysis and efficiency improvement10,11 while others invested themselves on systems design andanalysis12-16.Plant DescriptionThepower plant has a total installed power capacity of 396 MW. It is located 560 mabove sea level in the city of Zarqa, North east of Jordan 30 km of Amman. Itbegan producing power in the middle seventies. The power house is composed ofseven steam turbines units (3 × 33 + 4 ×66) MW and two gas turbines (1 ×14 + 1 ×19)MW at 100% load.
The power plant uses heavyfuel oil, which is obtained from anearby oil refinery. The total fuel consumed in 2006 was 504,030 tons.Properties for the heavy fuel oil obtained in the month of April, 2007 areshownin Table 1. Table 1: Properties of Heavy Fuel Oilused in Al-Husssein Power Plant for April 2007 Property Value Density at 15 oC 0.9705 g/ml. Total Sulfur 3.
67 wt% Flash Point 117 oC Kinematic Viscosity at 100 oC 35.52 cSt Pour Point +7 oC Ash Content 0.036 wt% Water and Sediment 0.
14 V% Gross Calorific Value (GCV or HHV) 42943.81 kJ/kg Net Calorific Value (NCV or LHV) 40504.58 kJ/kg Theschematic diagram of one 66MW unit is shown in Fig. 1.This unit employsregenerative feed water heating system. Feedwater heating is carried out in twostages of high pressure heaters (HPH1, HPH2) and two stages of low pressureheaters (LPH4, LPH5) along with one deaerating heat exchanger.
Steam issuperheated to793 K and 9.12 MPa in the steam generator and fed to theturbine.The turbine exhaust stream is sent to an air-cooled condenser and thecondensate to the condensate return tank (CRT). Then,the cycle starts overagain. The operating conditions of the power plant are summarized in Table 2. Table 2:Operating Conditions of the Power Plant Operating Condition Value Mass flow rate of fuel 5.0 kg/s Inlet gas volumetric flow rate to burner 188.790 Nm3/h Stack gas temperature 411.15 K Feed water inlet temperature to boiler 494.15 K Steam flow rate 275 ton/h Steam temperature 793.15 K Steam pressure 9.12 MPa Power output 56 MW Power input to FDC/fan 88 kW Number of fans 18 Mass flow rate of cooling air 23900 ton/h Combined pump/motor efficiency 0.95