Patent Application
20120269612
The present application and the resultant patent relate generally to gas turbine engines and more particularly relate to a compressor inlet casing with an integrally cast bearing housing half so as to accommodate thermal growth therein without impact on the position of the rotor shaft.
Generally described, the turbine section and the compressor section of a gas turbine engine are coupled via a rotor shaft. A number of circumferentially spaced rotor blades may be attached to the rotor shaft in both sections. The rotor blades in the turbine section are driven by hot combustion gases. The rotor shaft in turn drives the rotor blades in the compressor section so as to provide compressed air. Because the casing of the compressor may have a different thermal response time than the rotor wheel or rotor blades therein, the rotor blade tips may expand at a different rate than the casing so as to create the potential for the rotor blades to rub against the casing. Such rubbing may cause early rotor blade damages and possible failure. As a result, operational rotor blade/casing clearances must accommodate these differing expansion rates. These increased clearances may limit the efficiency of the overall gas turbine engine.
Current compressor inlet casing designs generally incorporate either a separate bearing housing in an inner barrel or the inner bellmouth or may have an integrally cast bearing housing that is machined into a solid inner bellmouth lower half. The bearing housing includes a number of bearing pads positioned about the rotor shaft for support during rotation thereof.
During operation, the integrally cast lower half bearing housing may expand due to the temperature of the bearing lubricating oil so as to rise vertically relative to the centerline of the inner bellmouth. This expansion is due in part to the asymmetric mass and the stiffness of the integrally cast lower half bearing housing. The thermal rise of the bearing housing is not desirable because it may push the rotor shaft off center. The integrally cast bearing housing, however, is cheaper as compared to a separate bearing housing. Greater clearances thus may be required so as to avoid casing rubbing.
There is a desire therefore for an improved compressor inlet casing design so as to reduce or eliminate the impact of thermal expansion on an integrally cast bearing housing. Preferably such an improved design would maintain the rotor shaft in position so as to allow tighter clearances about the casing and the rotor blades for an increase in overall system efficiency.
The present application and the resultant patent thus provide a compressor inlet casing. The compressor inlet casing may include an inner bellmouth and a bearing housing. The bearing housing may include an integrally cast first half connected to the inner bellmouth and a cavity positioned between the inner bellmouth and the integrally cast first half of the bearing housing.
The present application and the resultant patent further provide a method of operating a compressor. The method may include the steps of integrally casting a first half of a bearing housing in a compressor inlet casing, rotating a rotor shaft within the bearing housing, extending a lubricating oil conduit about the bearing housing, and thermally expanding the bearing housing within a cavity extending between the bearing housing and the compressor inlet casing.
The present application and the resultant patent further provide a compressor inlet casing. The compressor inlet casing may include an inner bellmouth and a bearing housing. The bearing housing may include an integrally cast first half connected to the inner bellmouth about a horizontal center line and a cavity positioned between the inner bellmouth and the integrally cast first half. The cavity may accommodate thermal expansion of the bearing housing.
These and other features and improvements of the present application and the resultant patent will become apparent to one of ordinary skill in the art upon review of the following detailed description when taken in conjunction with the several drawings and the appended claims.
Referring now to the drawings, in which like numerals refer to like elements throughout the several views,
The gas turbine engine 10 may use natural gas, various types of syngas, and/or other types of fuels. The gas turbine engine 10 may be anyone of a number of different gas turbine engines offered by General Electric Company of Schenectady, N.Y., including, but not limited to, those such as a heavy duty gas turbine engine and the like. The gas turbine engine 10 may have different configurations and may use other types of components. Other types of gas turbine engines also may be used herein. Multiple gas turbine engines, other types of turbines, and other types of power generation equipment also may be used herein together.
In use, the integrally cast first half 150 of the bearing housing 140 thus may be physically separated from the inner bellmouth 110 except about the horizontal centerline. The physical separation created by the cavity 180 thus allows the bearing housing 140 to thermally expand freely towards the inner bellmouth 110 about a bottom dead center position 190. Specifically, the cavity 180 ma be sized to accommodate thermal growth of the bearing housing 140. By allowing the bearing housing 140 to expand, the rotor shaft 45 may stay positioned about the centerline of the inner bellmouth 110. Given such, the eccentricity of the rotor shaft 45 may be minimized. Specifically, the impact of the heating of the bearing housing 140 by the lubricating oil and the like flowing therethrough may be minimized.
By avoiding eccentricities created by the thermal growth of the bearing housing 140, overall compressor clearances may be reduced so as to provide increased efficiency and overall performance. The compressor inlet casing 100 described herein thus provides such an improved performance but with the bearing housing 140 having the integrally cast first half 150 for overall lower costs.
It should be apparent that the foregoing relates only to certain embodiments of the present application and the resultant patent. Numerous changes and modifications may be made herein by one of ordinary skill in the art without departing from the general spirit and scope of the invention as defined by the following claims and the equivalents thereof.
