Ceramic Vane Demonstration in an Industrial Turbine

Abstract

A U. S. Department of Energy (DOE) program with the Allison Engine Company will demonstrate ceramic vanes in an industrial turbine. First-stage ceramic vanes and their metallic mounts are to be designed, fabricated, and operated in a relatively short-term engine test (up to 50 hr). The ceramic vanes and mounts will then be retrofitted into an existing turbine for operation at a commercial site for an extended duration test (up to 8000 hr). The ceramic vanes and metallic mounts have been designed. Thermal and stress analyses of the vanes have calculated acceptable fast fracture stress levels and probabilities of survival exceeding 99.99% for turbine continuous power and emergency shutdown (thermal shock) conditions. The maximum calculated steady-state stress is 169 MPa (24.5 ksi) at a material temperature of 1182°C (2160°F). Consequently, currently available ceramics appear to provide acceptable fast fracture strengths for use in industrial turbines. Long-term materials tests will evaluate the life times and retained strength of ceramics at stress and temperature levels in the range calculated from the ceramic vane analyses. The results of these tests will support the decision on which vane material will be used in the long duration turbine demonstration. A successful demonstration could provide a basis for incorporating first-stage ceramic vanes into current generation industrial turbines and also the introduction of ceramic airfoils into downstream rows of future high temperature Advanced Turbine System (ATS) engines.