Performance Entitlement of Supercritical Steam Bottoming Cycle

A supercritical steam bottoming cycle has been proposed as a performance enhancement option for gas turbine combined cycle power plants. The technology has been widely used in coal-fired steam turbine power plants since the 1950s and can be considered a mature technology. Its application to the gas-fired combined cycle systems presents unique design challenges due to the much lower gas temperatures (i.e., 650 °C at the gas turbine exhaust vis-à-vis 2000 °C in fossil fuel-fired steam boilers). Thus, the potential impact of the supercritical steam conditions is hampered to the point of economic infeasibility. This technical brief draws upon the second-law based exergy concept to rigorously quantify the performance entitlement of a supercritical high-pressure boiler section in a heat recovery steam generator utilizing the exhaust of a gas turbine to generate steam for power generation in a steam turbine.