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Siemens Power Generation, Inc., based in Orlando, Fla., is proving that ceramics are ideal materials for power turbine applications. The company uses a combination of monolithic ceramic and ceramic-coated metal heat shields to line the combustion chamber of its SGT5-4000F engine. Various liner materials had been used in earlier generations of this engine family, but the ceramic heat shields allow a large amount of cooling air to be saved, thus enhancing the efficiency of the turbine and allowing NOx emissions to be reduced. The heat shield attachment elements are protected against the hot combustion gases by cooling air distributed through many minute cooling holes. Millions of operating hours have been successfully accumulated on these parts.
In addition to the combustor heat shields, the company extensively relies on advanced thermal barrier coatings for hot section blades, vanes and other components to further improve efficiency, increase power output and reduce emissions. Ongoing efforts to improve thermal barrier coating performance are being funded both internally by Siemens and by the U.S. Department of Energy (DOE), the National Institute of Standards and Technology (NIST) and other government agencies.
Siemens is also developing ceramic matrix composites for future gas turbine applications. These composites offer improvements in strength and reliability over conventional monolithic materials and can be used more extensively throughout the turbine hot section. Collaboration partners include ATK-COI Ceramics Inc. and Solar Turbines in San Diego, Calif., as well as government agencies, national laboratories, universities, and other end users. An initial test product (a Solar Turbines combustor liner) has exceeded 19,000 operating hours in a field engine-a world record. Expansion to other applications is planned.
For more information about these developments, contact Siemens Power Generation, Inc. at (407) 736-7381 or click on the link below to visit the company's website.