Energy-exergy analysis of the Hamitabat combined cycle power plant and suggestions for improvement

With increasing energy demands of countries and the energy crisis that emerged at the end of 2021, resource diversity in energy production has gained great importance. Although investments in renewable energy sources increase each year, they are insufficient to meet the energy demand. The rapid transition of European countries to renewable energy due to environmental policies caused to decrease the investments in coal and natural gas fired power plants. This approach resulted with an insufficient energy supply and caused the energy crisis. Many countries have met their energy demands by commissioning base load power plants such as coal and natural gas fired plants. In this regard, natural gas and coal fired thermal power plants play an important role in power generation. For this reason, availability and rehabilitation studies, especially in natural gas cycle power plants, are of great importance. In this study, Hamitabat natural gas combined cycle power plant (CCPP) located in Lüleburgaz district of Kırklareli was investigated. Hamitabat CCPP is Turkey's first natural gas CCPP. The plant was renovated in 2017 with a €520 million project and its installed power capacity was increased to 1220 MW. Within the scope of the study, the energy and exergy analysis of the Hamitabat CCPP is carried out. With these analyses, alternative approaches can be determined to improve the performance through a component-based examination of the power plant. In the study, Engineering Equation Solver (EES) program was used with actual power plant data. Compressor, combustion chamber, gas turbine, waste heat recovery steam generator, steam turbines, condenser, pumps and auxiliary components of the Hamitabat CCPP were examined in detail. The results show that the combustion chamber has the highest rate of exergy destruction and the equipment is responsible for 77.607% of total exergy destruction. Combustion chamber is followed by the waste heat recovery steam generator, compressor, gas turbine and low pressure turbine. Equipments with the highest exergy efficiency values are gas turbine, high pressure turbine, compressor, medium pressure turbine and hydraulic turbine. It has been determined that the equipments with the lowest exergy efficiency are the combustion chamber and the condenser pump. Based on the exergy destruction rate and exergy efficiency values, the equipments with the highest improvement potential are combustion chamber, compressor and waste heat recovery steam generator. The energy efficiency of the power plant is calculated as 59.70% while the exergy efficiency is 58.52%. The total rate of exergy destruction is determined to be 396.084 MW and the total improvement potential is 72.567 MW. In addition, parametric analyzes were made depending on the temperature and pressure values. In this regard the effect of condenser pressure on the low-pressure steam turbine and overall plant performance, the effect of high-pressure steam turbine temperature and pressure on the exergy destruction rate and total production of the high-pressure steam turbine, the effect of intermediate-pressure steam turbine temperature on the exergy destruction and total production of the intermediate-pressure steam turbine were investigated. It is found that an increase of 1.2kPa in the condenser pressure reduces the power generation in the low-pressure steam turbine by 3.2MW. The negative impact of increasing the condenser pressure decreases the energy and exergy efficiency of the plant by 0,312% and 0.306%, respectively. Increasing the high-pressure steam turbine inlet temperature by 5.1% from 592oC to 622oC increases the total power production of the steam turbines by 8.6 MW, and decreases the exergy destruction rate of the high-pressure steam turbine by 2.8 MW. Increasing the high-pressure steam turbine pressure from 16.8 MPa to 19.5 MPa reduces the power of the turbine by 2.3MW, and increases the exergy destruction rate of the high-pressure steam turbine by 2,7 MW. An increase of 30oC in the inlet temperature of intermediate-pressure steam turbine improves the total steam turbine power production by 8.1 MW and decreases the exergy destruction rate of the low-pressure steam turbine by 2.8 MW. The positive impact of increasing inlet temperature of intermediate-pressure steam turbine has the potential of improving the energy and exergy efficiency of plant by 0.79% and 0.77%, respectively.