Energy, Exergy and Exergy economy Analysis of three Scenario of Thermal Plant

Steam power plants are an advanced and complex design of the Rankin steam-liquid cycle. Therefore, understanding the concepts of effective parameters in increasing energy and exergy efficiency and also exergoeconomic are very important. The purpose of this study is to investigate the three basic scenarios of steam power plants, till the required changes in design and its effects on power plant efficiency to be determined. The third scenario has a preheater, a deaerator and two turbine extraction. The second scenario has a turbine extraction and preheater. In third scenario, energy and exergy efficiency are 20.74% and 26.91%, respectively. it’s increases of energy and exergy efficiency relative to second scenario are equal to 19.13% and 9.48%, respectively. Exergoeconomic analysis has shown that boiler and turbine have the highest total cost of investment, maintenance and exergy destruction, hence special attention should be paid to this equipment. The high relative cost factor of the boiler (r) indicates that the boiler efficiency can provide an overall improvement in the cost of this equipment. This can be done by reducing the exergy destruction by preheating and reducing losses and use of excess air. The Exergoeconomic coefficient of fk turbine is high. This means that to reduce the cost of the turbine, the possibility of reducing parameters such as inlet steam temperature, turbine pressure and it’s efficiency should be given more attention.