Fuel-Flexible Combined Cycles for Utility Power and Cogeneration
Two combustion turbine combined cycle power plants have been studied for performance and operating economics. Both power plants are in the size range that will be suitable for small utility application and use less than 106 GJ/hr (100 million Btu/hr). The Powerplant and Industrial Fuel Use Act of 1978 has exempted power plants of this size from the requirement to use coal. The first power plant is based on the Solar Turbines International (STI) Mars industrial gas turbine. The combined gas turbine/steam cycle is direct fired with No. 2 diesel fuel. A net plant efficiency of 39.7 percent (HHV) is obtained at the 11.56-mW growth rating of the Mars engine for a turbine rotor inlet temperature of 1331 K (1935 F). A total installed cost for the system is estimated to be within the band 545 to 660 $/kW. The second power plant is based on STI’s Centaur industrial gas turbine. The combined gas turbine/steam cycle is indirectly fired with solid fuel although it is intended that the installation can be initially fired with a liquid fuel. A net plant efficiency of 25.0 percent (HHV) is obtained burning Illinois No. 6 coal at a rating of 3.78 mW with a turbine inlet gas temperature of 1117 K (1550 F).