Fogging for Evaporative Cooling Effects on Siemens V94.2 Gas Turbine Performance

In order to study the effects of ambient temperature and relative humidity on the performance of the Siemens V94.2 gas turbine, installed as a topper in an IGCC complex and fed with syngas, a mathematical model of the engine has been developed and implemented into GateCycle environment. The model was fine tuned using experimental data of plant. Thermodynamic analysis of the gas turbine performance, depending on ambient temperature and relative humidity, has been carried out. Results show the strong dependence of engine performance on ambient temperature (in the range from 30 °C to 40 °C). Theoretical and experimental results have been shown that ambient air humidity decreases power losses due to high external temperature. In order to optimize power production in this temperature range, an artificial humidifier was implemented into the model. Furthermore, “Fogging for Evaporative Cooling” technique effects on performance of the gas turbine have been studied. Using GateCycle model, simulations have been carried out as regards to temperature variation in the range which power losses occur. Two control strategies of the artificial air humidifier have been implemented: the first is characterized by an air humidity constant at the intake of the compressor (set to 95%); the second one is characterized by an air temperature constant at the intake of the compressor (set to the temperature corresponding to maximum IGV opening). For both control strategies, power losses recovery can be achieved depending on base air humidity and temperature. Applying the second control strategy, lower water consumption was achieved but a compression ratio very close to the limit value was observed.