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  Turbine power plant having minimal-contact brush seal augmented labyrinth sealUSPTO Application #: 20060064988Title: Turbine power plant having minimal-contact brush seal augmented labyrinth seal Abstract: A stationary gas turbine engine includes an axial compressor; a turbine; a stationary inner barrel downstream of the compressor; a brush seal including a ring-shaped holder supported by the inner barrel, and a multiplicity of inwardly extending bristle members having an ambient temperature clearance of not less than 0.015 percent of a rotor land region diameter of the rotor under cold conditions for restricting air passage into the chamber from the compressor. The flow of cooling air from the chamber is preferably alterable by a fluid port extending through one wall of the inner barrel, the fluid port being connected to an auxiliary source of pressure air external of the inner barrel, whereby pressure air from the auxiliary source augments the flow of cooling air from the chamber. A calibrated needle valve can adjustably restrict the flow of auxiliary air for controlling a monitored operating parameter such as the temperature within the chamber. The engine can have an outer barrel surrounding the inner barrel, air flowing therebetween toward the combustor, and including a radial fluid port, and a fluid conduit connected between the passage and the fluid port, the auxiliary source being connected to the fluid port external of the outer barrel. A method for controlling cooling air flow in the power plant includes providing the brush seal; connecting the brush seal in augmenting relation to the labyrinth seal; and spacing the bristles from the land region of the rotor. (end of abstract)
Agent: F. Lindsey Scott Suite B - Plano, TX, US Inventor: Steve Ingistov USPTO Applicaton #: 20060064988 - Class: 060805000 (USPTO) Related Patent Categories: Power Plants, Combustion Products Used As Motive Fluid, Combustion Products Generator, Having Turbine The Patent Description & Claims data below is from USPTO Patent Application 20060064988. Brief Patent Description - Full Patent Description - Patent Application Claims
BACKGROUND [0001] The present invention relates to turbine power plants and more particularly to large, stationary turbine power generators of the type used for utility services. [0002] A typical stationary turbine power plant, known as Model Series 7001 simple cycle, single shaft, heavy duty gas turbine (Frame-7 machine), is available from General Electric of Schenectady, N.Y. In this and similar gas turbines, a seal is located between an axial compressor rotor and a stationary inner barrel member, a chamber within the inner barrel member being supplied with cooling air from the last stage of the compressor by a controlled amount of leakage through the seal. The cooling air is then utilized for cooling of a first turbine stage of the machine. A set of rotor bearings is located in the cavity. [0003] Leakage in excess if a predetermined amount that is required for cooling of the turbine becomes parasitic and contributes to inefficiency of the machine. This is a serious problem in turbine power plants of the prior art, in that the labyrinth seals degrade in operation because of thermal expansions and other factors that cause knife-edge members and adjacent rotating elements of the seals to be worn away quickly, particularly during shut-down sequences. This is caused, for example, by shrinkage of the inner barrel member being more rapid than shrinkage of the rotor at the seal to the rotor being more massive. Thus in the frame-7 machines, the bypass air flow increases to approximately 100,000 lb/hr from the 30,000 lb/hr that is considered optimal. Consequently, there is a loss of power that is believed to be between 1.5 MW and 3.0 MW. [0004] Brush seals for gas-turbine engines are known, being disclosed, for example in "Brush Seals" Directions, September 1993 . As disclosed therein, a brush seal consists of densely packed metallic bristles that are welded between a down-stream backing plate and an up-stream side plate. In a typical round seal for aircraft turbine applications, the plates are ring-shaped, the bristles extending radially inwardly at a trailing lay angle and making an interference contact with a rotor element, so that the bristles become curved and follow the rotor as it grows and shrinks during engine operation. [0005] Brush seals have not been applied to existing large power plant turbines for a number of reasons. For example, the existing rotor components, being made from elements of low carbon steel alloys that are selected for certain thermal expansion properties, are believed to be unsuitable as wear surfaces for contact by the bristles, particularly during the extended operation cycles that are demanded of stationary power plants. Suitable hardening of applicable compressor rotor members is believed to be prohibitively expensive, particularly in existing equipment. [0006] Thus there is a need for an improved rotor seal for large stationary plants, that overcomes the disadvantages of the prior art. SUMMARY [0007] The present invention meets this need by providing a turbine power plant with a combination brush and labyrinth compressor seal wherein the brush seal operates in a non-contact mode following start-up. In one aspect of the invention, a stationary gas turbine engine for the power plant includes a multistage axial compressor that has a rotor having a cylindrical land region downstream of a last-stage of the compressor, the land region having an outside diameter D; a turbine shaft-coupled to the rotor of the compressor; a combustor fluid-coupled between the compressor and the turbine; a stationary inner barrel downstream of the compressor, air flowing from the compressor to the combustor passing outside of the inner barrel, a chamber within the inner barrel forming a passage for cooling air from the compressor, the cooling air flowing from the chamber and being mixed with combustion gases upstream of the turbine; a brush seal for restricting air passage into the chamber from the compressor, the brush seal including a ring-shaped holder; a multiplicity of bristle members extending radially inwardly from the holder toward the land region of the rotor, outer extremities of the bristle members being rigidly retained relative to the holder; and means for fastening the holder to the inner barrel, wherein, when the power plant is inactive, the bristles have an ambient temperature clearance of not less than 0.015 percent of the diameter D from the land region of the rotor. [0008] The engine can further include means for selectively altering the flow of cooling air from the chamber, including a passage extending through one wall of the inner barrel; means for connecting the fluid port to an auxiliary source of pressure air external of the inner barrel, whereby pressure air from the auxiliary source augments the flow of cooling air from the chamber; and means for changeably restricting flow of pressure air into the chamber from the auxiliary source of pressure air. The compressor can provide at least a portion of the auxiliary source of pressure air. The means for changeably restricting can include means for removably mounting a device being a plug or a jet in the passage. [0009] Preferably the means for selectively altering the flow of cooling air also includes a valve for adjustably restricting flow of pressure air into the chamber from the auxiliary source of pressure air; and means for monitoring an operating parameter of the engine, the operating parameter being responsive to the flow of cooling air from the chamber. The valve is preferably a calibrated needle valve for facilitating repeatable control of the cooling flow. The means for monitoring can include a temperature sensor for indicating temperatures within the chamber. The engine can also have an outer barrel surrounding the inner barrel and including a fluid port extending radially through one wall thereof, the gas flow from the compressor to the combustor passing between the outer barrel and the inner barrel, the means for connecting the passage including a fluid conduit connected between the passage and the fluid port, and means for connecting the auxiliary source of pressure air to the fluid port external of the outer barrel. [0010] The engine can further include an insert ring connecting segments of the inner barrel, the insert ring being located proximate the land region of the rotor, the means for fastening the brush seal to the inner barrel including the holder being fastened to the insert ring by a plurality of threaded fasteners. Preferably the brush seal, including the holder thereof, is segmented for facilitating assembly with the insert ring. [0011] In another aspect of the invention, a turbine power plant improvement includes a brush seal connected to a stationary barrel member between an axial compressor outlet and a cavity within the barrel member for augmenting a labyrinth seal that limits the flow of cooling air into the cavity, the brush seal having a ring-shaped holder, a multiplicity of bristle members being rigidly anchored to the holder and extending radially inwardly therefrom toward a rotor land region, wherein the bristles have an ambient temperature clearance of not less than 0.015 percent of a diameter D of the land region when the power plant is inactive. [0012] In a further aspect of the invention, a method for controlling cooling air flow in a turbine power plant having a multistage axial compressor, a turbine shaft-coupled to a rotor of the compressor, a combustor fluid coupled between the compressor and the turbine, and a labyrinth seal between the rotor and a stationary inner barrel member, the rotor having a cylindrical land region of diameter D, includes the steps of: [0013] (a) providing a brush seal having a ring-shaped holder, a multiplicity of bristle members extending radially inwardly from the holder toward the land region of the rotor, outer extremities of the bristle members being rigidly retained relative to the holder; [0014] (b) connecting the brush seal in augmenting relation to the labyrinth seal; and [0015] (c) spacing the bristle members from the land region of the rotor by an ambient temperature clearance of not less than 0.015 percent of the diameter D when the power plant is inactive. [0016] The power plant can include an insert ring fastened to the inner barrel in axially spaced relation to a portion of the rotor member, the method including the further steps of: [0017] (a) removing the insert ring from the inner barrel member; [0018] (b) providing an adapter ring; [0019] (c) mounting the brush seal to the adapter ring; and [0020] (d) fastening the adapter ring to the inner barrel member in place of the insert ring. [0021] The step of providing the adapter ring can include the step of modifying the insert ring. The method can include the further steps of: [0022] (a) providing an auxiliary source of pressure air; Continue reading... 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