Thermo-economic Analysis of the Existing Options for Feed Water Heating Repowering, Using a Stepwise Method

Adding gas turbine units to steam power plants for enhancing steam cycle’s properties and regenerating heat from adjunct cycle(s) have been known as repowering. Repowering methods are divided into two main categories, partial and full repowering. One of the latest methods of partial repowering is parallel feed water heating repowering. In this paper the mentioned method has been applied to Shahid Rajaee power plant. Cost functions of generated-electricity and exergy efficiency are defined as objective functions in one and two objective optimizations. Finally, the most suitable scenario has been chosen to apply this method on, considering desirable technical and economic parameters for partial and nominal load. The results of the chosen design are: 3.4% and % 27 increases in exergy efficiency and steam power plant capacity, respectively.