Thermodynamics analysis and performance optimization of a reheat - Regenerative steam turbine power plant with feed water heaters

This study investigates the thermodynamics performance analysis of a reheat-regenerative steam power plant using CyclePad V2.0 software. The impact of closed Feedwater Heaters (FWHs) on the functionality indices of the selected power plant was examined. Results of the study show that as the number of closed FWH increases from one to ten, the thermal efficiency and boiler efficiency rise from 42.17% to 45.97% and 79% to 96.4%, respectively. The fuel consumption, heat rejected to the condenser, heat rate, network output and heat input to the power cycle decrease from 9.697 kg/s to 4.686 kg/s, 209.32 kJ/kg to 129.68 kJ/kg, 8536.87 kJ/kWh to 8318.48 kJ/kWh, 152.22 MW to 102.89 MW and 361.11 kJ/kg to 237.98 kJ/kg, respectively as the number of FWHs increased. On the contrary, specific steam consumption increases from 0.0234 kg/kWh to 0.0370 kg/kWh. Moreover, fuel consumption decreases by 51.7% and the efficiency gain (eta) successively diminish with increment in the number of closed FWHs. Also, both enthalpy rise and temperature rise increase with increase in the number of closed FWHs. As the number of heaters increases, so is the total temperature rise of feed water (Delta t(fw)), by regeneration, less becomes the heat added to water in the boiler, more becomes the mean temperature of heat addition, and more is the cycle efficiency. This result implies that a decrease in operating cost of the plant and environmental impacts can be achieved with an increase in the number of closed FWHs. Hence, this study establishes the importance of closed FWHs in revamping the performance of a steam power plant.