Technical Analysis of Conversion of A Steam Power Plant to Combined Cycle, Using Two Types of Heavy Duty Gas Turbines

Due to long life of steam power plants in Iran, transformation of steam cycles to combined cycles is under consideration. Bandar-Abbas steam power plant with capacity of 320 MW has been analyzed in this work. This old plant is located near the harbor city of Bandar-Abbas at southern Iran. Method of exergy analysis is used to study the current and the repowered systems. Optimum state of the repowered cycle is also obtained using exergy analysis.  In this work, a point by point analysis of Bandar-Abbas steam power plant is performed for different modes of full repowering, using exergy analysis method. For this purpose, V94.2 and V94.3A gas turbines are used and effect of duct burner is investigated for each case. The results show that at the best repowering mode, power plant efficiency is 34.5% higher than the design efficiency of the current steam plant. Minimum rate of exergy destruction rate is 6711 MW at this mode and the heat rate reduces by 26.6%. According to the results, increase of fuel consumption in duct burner and use of V94.2 gas turbine are not recommended for repowering of Bandar-Abbas power plant.