Bureau of Mines Progress in Developing Open and Closed-Cycle Coal-Burning Gas Turbine Power Plants

Closed-cycle developments include tests of a turbocompressor with hydrodynamic gas bearings. The working fluid is inert gas, with turbine inlet temperatures to 1600 F. A refractory-metal turbine for tests at 1950 F is described. Open-cycle operations for 1963 hours with turbine blades specially designed to resist erosion by coal ash particles are described. Estimated life of the rotor and stator blading was 20,000 and 5000 hours, respectively. Efforts to increase blade life by reducing the amount of ash entering the turbine through improvements in combustion and ash separation systems are described.