General Electric Company

Peter G Ipsen

Gary L Kalan

Control apparatus is disclosed for limiting overspeed in a steam turbine following a sudden loss in load. The apparatus includes at least one valve disposed in the steam conduit interconnecting higher and lower pressure sections of the turbine and an actuator for controlling operation of the valve between a fully open position and a pressure-relief position wherein the valve functions as a pressure relief valve. During normal operation, the valve is maintained in the fully open position. On receipt of a turbine overspeed signal, the valve is actuated to the pressure relief position and a volume of steam at a preselected pressure, necessary to open the valve, is held back within the turbine stages, crossovers, and so forth. This retained steam is thus prevented from adding energy to increase the speed of the turbine rotor. During turbine startup, the valve is operated in its pressure relief position to permit preheating of the higher pressure sections of the turbine, avoiding long and costly startup procedures.

Steam turbine control apparatus

An air-sealed oil deflector is disclosed which prevents leakage of oil from bearings of a rotating shaft and which prevents the ingestion of unfiltered atmospheric air which can lead to contaminant build-up and damage to the shaft. The air-sealed deflector includes an annular plenum surrounding the shaft and an annular feed slot interposed between the shaft and the plenum to fluidly interconnect the plenum with the chamber between at least two seal rings immediately adjacent the shaft. The plenum is adapted to receive a continuous flow of forced air from an air supply system including an air prime mover and means for filtering air drawn from the atmosphere which serves as the ultimate air source. The plenum being relatively large in volume, and having a cross-sectional area large with respect to the air feed conduit to the plenum, provides a very uniform source for air flow radially inward, in a sheet-like fashion, toward the shaft through the feed slot. The air-seal is formed as the sheet-like flow of air is released between working clearances between the shaft and the seal rings. A perforated diffuser ring mounted in the feed slot contributes to the desired pressure distribution and eliminates detrimental viscous drag effects.

Air-sealed oil deflector

The disclosure relates to the construction of large fluid conduits and particularly to steam conduits used in large power plants. In some power plants, steam is transferred from the exhaust of a higher pressure turbine section into the inlet of a lower pressure turbine section through a steam conduit sometimes referred to as a cross-over which may include several bellows type joints. If the turbine rotor speed exceeds rated speed, then it is desirable to limit the maximum speed to be attained by the turbine rotor. The present invention provides a reliable and advantageous construction which will decrease the maximum speed of a turbine rotor over designs now available in the prior art.

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Schenectady, NY, United States of America

Peter G Ipsen