Rintaro Chikami

Development of Air-Cooled Ceramic Nozzles for a Power Generating Gas Turbine

The development of air-cooled ceramic nozzle vanes for a power generating gas turbine has been reported. To make up the limited temperature resistance of present ceramic materials, the utilization of a small amount of cooling air has been studied for the first stage nozzle vanes of a 1500°C class gas turbine.A series of cascade tests were carried out for the designed air-cooled Si3N4 nozzle vanes under 6 ata and 1500°C conditions. It was confirmed that the maximum ceramic temperature can be maintained below 1300°C by a small amount of cooling air. In spite of the increased thermal stresses by local cooling, all Si3N4 nozzle vanes survived in the cascade tests including both steady state and transients of emergency shutdown and the possibility of air cooled ceramic nozzle was demonstrated for a 1500°C class gas turbine application.Copyright

A Study of Cycle Performance of Ceramic Gas Turbines

A study has been carried out to assess the performance improvement of a combined cycle used for an industrial power plant when ceramic turbine components are employed. This paper presents the details of this study. Performance improvement is obtained as a result of reduced blade cooling air. In this study four different kinds of combined cycles were investigated and these are listed below:A. Combined cycle with a simple gas turbine.B. Combined cycle with an inter-cooled gas turbine.C. Combined cycle with a reheat gas turbine.D. Combined cycle with an inter-cooled reheat gas turbine.Results of this study indicate that the combined cycle with a simple gas turbine is the most practical of the four cycles studied with an efficiency of higher than 60%. The combined cycle with reheat gas turbine has the highest efficiency if a higher compressor exit air temperature and a high gas temperature (over 1000°C) to reheat the combustion system are used. A higher pressure ratio is required to optimize the cycle performance of the combined cycle with the ceramic turbine components than that with the metal turbine components because of reduced blade cooling air. To minimize leakage air for these higher pressure ratios, advanced seal technology should be applied to the gas turbines.Copyright