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Controlling a rabbet load and air/oil seal temperatures in a turbine

United States Patent

April 30, 2002
View the Complete Patent at the US Patent & Trademark Office
During a standard fired shutdown of a turbine, a loaded rabbet joint between the fourth stage wheel and the aft shaft of the machine can become unloaded causing a gap to occur due to a thermal mismatch at the rabbet joint with the bearing blower turned on. An open or unloaded rabbet could cause the parts to move relative to each other and therefore cause the rotor to lose balance. If the bearing blower is turned off during a shutdown, the forward air/oil seal temperature may exceed maximum design practice criterion due to "soak-back." An air/oil seal temperature above the established maximum design limits could cause a bearing fire to occur, with catastrophic consequences to the machine. By controlling the bearing blower according to an optimized blower profile, the rabbet load can be maintained, and the air/oil seal temperature can be maintained below the established limits. A blower profile is determined according to a thermodynamic model of the system.
Schmidt; Mark Christopher (Niskayuna, NY)
General Electric Company (Schenectady, NY)
09/ 635,086
August 8, 2000
This invention was made with Government support under Contract No. DE-FC21-95MC-31176 awarded by the Department of Energy. The Government has certain rights in this invention.