Gas turbine with Kalina bottoming cycle versus evaporative gas turbine cycle

摘要

The purpose of this study is to compare a combined cycle using a Kalina cycle as the bottoming process with an evaporative gas turbine (EvGT) cycle. The working fluid in the Kalina cycle is an ammonia-water mixture, which provides some thermodynamic advantages over the conventional steam Rankine cycle. The EvGT cycle also uses a mixture as the working fluid, i.e., air and water Waste heat from the gas turbine is used to humidify the compressed combustion air, increasing the mass flow through the expander and thereby raising the power output. The industrial gas turbine GTX100 and the aeroderivative Trent have been investigated. For the GTX1OO, the EvGT cycle gives a higher electrical efficiency than the single-pressure kalina cycles. However, the electrical efficiency for a triple-pressure Kalina cycle is higher than for the EvGT cycle. The GTX1OO is intercooled and recuperated in the EvGT cycle. For the Kalina cycles, a simple cycle GTXlOO has been used, as the exhaust gas should be used as a heat source for the bottoming cycle. For the Trent, all Kalina cycles give higher electrical efficiencies than the EvGT cycle, since the lower exhaust gas temperature of the Trent gives the Kalina cycle an advantage.