Concise Estimation Model of Thermodynamic Performance for Bottom Cycle of F/G/H-class Heavy Duty Gas Turbine Combined Cycle

In this study, a triple pressure Rankine bottom cycle with reheating was modeled. Its thermodynamic performance was evaluated with the gas turbine exhaust parameters and power outputs of various F-class and H-class gas turbines referred from gas turbine world handbook 2018. We looked into several key parameters for the bottom cycle of modern heavy duty gas turbine combined cycle, e.g. the main steam pressure and steam temperature, evaporator pinch point, economizer approach point and steam turbine section efficiencies. The results prove that key parameters for the bottom cycle of H-class gas turbine are more advanced than F-class, with an improvement in exergetic efficiency of bottom cycle about 1.27~1.70 percentage points. And based on gas turbine exhaust parameters, a concise estimation model for steam turbine outputs, steam mass flow of heat recovery steam generator and its exhaust temperature is proposed. It will give some advice to the original engineering analysis and engineering design for the modern heavy duty gas turbine combined cycle. © 2019 Chin. Soc. for Elec. Eng.