Turbine power plant having minimal-contact brush seal augmented labyrinth seal
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.
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The present invention relates to turbine power plants and more particularly to large, stationary turbine power generators of the type used for utility services.
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.
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.
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.
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.
Thus there is a need for an improved rotor seal for large stationary plants, that overcomes the disadvantages of the prior art.
SUMMARYThe 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.
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.
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.
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.
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.
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:
(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;
(b) connecting the brush seal in augmenting relation to the labyrinth seal; and
(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.
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:
(a) removing the insert ring from the inner barrel member;
(b) providing an adapter ring;
(c) mounting the brush seal to the adapter ring; and
(d) fastening the adapter ring to the inner barrel member in place of the insert ring.
The step of providing the adapter ring can include the step of modifying the insert ring. The method can include the further steps of:
(a) providing an auxiliary source of pressure air;
(b) fluid-connecting the auxiliary source to an interior cavity portion of the inner barrel member for augmenting the flow of cooling air;
(c) connecting an adjustable valve between the auxiliary source and the inner barrel member for variably restricting air flow from the auxiliary source and the inner barrel member;
(d) monitoring an operating parameter of the power plant; and
(e) adjusting the adjustable valve in response to changes in the operating parameter.
DRAWINGSThese and other features, aspects, and advantages of the present invention will become better understood with reference to the following description, appended claims, and accompanying drawings, where:
The present invention is directed to a turbine power plant having improved control of cooling bypass air. With reference to
The turbine machine 10, being of the type that is commercially available as Series 7001 heavy duty gas turbine from the previously identified General Electric Corp., has a somewhat protracted start-up sequence that lasts over one hour and a shut-down sequence that lasts approximately one hour as characterized in
According to the present invention, and with further reference to
4,500 per square inch.
In an exemplary configuration of the machine 10′, a retainer plate 48 holds the brush seal 40 in fixed relation to the barrel member 18 by interlocking engagement with a counterpart of the insert ring, designated adapter ring 32′, the backing plate 42 having a generally L-shaped cross-section, one leg of which axially projects into the adapter ring 32′. The retainer plate 48 is fastened to the insert ring 32′by a plurality of threaded fasteners 50. In the exemplary configuration of
It is contemplated that the brush seal 40 be added to existing turbine machines 10 having worn labyrinth seals 22 as described above. In the present invention this facilitated by the need for modification of the insert ring 32 only. Particularly, the adapter ring 32′ can be formed by axially shortening the existing insert ring 32, forming an annular channel as indicated at 54, and forming threaded openings 56 for the fasteners 50. The adapter ring 32′ can be segmented as described above in connection with the insert ring 32.
It is also contemplated that the brush seal 40 be used in “fresh” installations having no wear of the labyrinth seal 22. In such cases, the labyrinth seal radial spacing LD, which is only 0.03 inch, quickly increases as a result of wear during shut-down as described above. Nevettheless, it may be desired to augment the flow of cooling air into the chamber 28. Accordingly, and as shown in
Also, some or all of the passages 60 can be fluid-connected to an auxiliary source 66 of pressure air as shown In
The turbine machine 10′ of the present invention provides improved control of cooling air into the chamber 28 for significantly increased output and efficiency in typical large power plant installations. Under conditions presently encountered, it is believed that the present invention will provide approximately 1.5 megawatts of additional power output from a typical installation of the Frame-7 machine, resulting in a savings on the order of $250,000 per machine, the installation cost being on the order of $30,000.
Although the present invention has been described in considerable detail with reference to certain preferred versions thereof, other versions are possible. Therefore, the spirit and scope of the appended claims should not necessarily be limited to the description of the preferred versions contained herein.
Claims
1. A stationary gas turbine engine for a power plant, comprising:
- (a) a multistage axial compressor, the compressor having a rotor, the rotor having a cylindrical land region downstream of a last-stage of the compressor, the land region having an outside diameter D;
- (b) a turbine shaft-coupled to the rotor of the compressor;
- (c) a combustor fluid coupled between the compressor and the turbine;
- (d) a stationary inner barrel member downstream of the compressor, air flowing from the compressor to the combustor passing outside of the inner barrel member, a chamber within the inner barrel member 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; and,
- (e) a brush seal for restricting air passage into the chamber from the compressor, the brush seal comprising:. (i) a ring-shaped holder; (ii) 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 (iii) means for fastening the holder to the inner barrel member.
2. (canceled)
3. (canceled)
4. (canceled)
5. (canceled)
6. (canceled)
7. (canceled)
8. (canceled)
9. The engine of claim 1, further comprising an insert ring connecting segments of the inner barrel member, the insert ring being located proximate the land region of the rotor, wherein the means for fastening the brush seal to the inner barrel member comprises the holder being fastened to the insert ring by a plurality of the threaded fasteners.
10. The engine of claim 9, wherein the brush seal, including the holder thereof is segmented for facilitating assembly with the insert ring.
11. 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, the improvement comprising a brush seal connected to the inner barrel and augmenting the labyrinth seal, being fluid connected in series therewith, the brush seal comprising:
- (a) a ring-shaped holder;
- (b) 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
- (c) means for fastening the holder to the inner barrel member.
12. (canceled)
13. (canceled)
14. (canceled)
15. (canceled)
16. (canceled)
17. 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, comprising the steps of:
- (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;
- (b) connecting the brush seal in augmenting relation to the labyrinth seal; and
- (c) spacing the bristle members from the land region of the rotor.
18. The method of claim 17, wherein the power plant includes an insert ring fastened to the inner barrel member in axially spaced relation to a portion of the rotor member, the method comprising the further steps of:
- (a) removing the insert ring from the inner barrel member;
- (b) providing an adapter ring;
- (c) mounting the brush seal to the adapter ring; and
- (d) fastening the adapter ring to the inner barrel member in place of the insert ring.
19. The method of claim 18, wherein the step of providing the adapter ring comprises the step of modifying the insert ring.
20. (canceled)
21. A refurbished gas turbine engine component having at least one knife edge seal for inhibiting air leakage through an intercomponent gap between the component and a second component, the refurbished component characterized by:
- a) a brush seal mounted on the refurbished component in tandem with the knife edge seal, the bristles of the brush seal extending toward the second component for impeding the leakage of air through the intercomponent gap.
22. The refurbished component of claim 1 characterized in that the component comprises two component segments, the brush seal is also segmented and the brush seal segments are mounted in a circumferentially extending groove so that the seal is installable and removable by separating the component segments and sliding the brush seal segments circumferentially in the groove.
23. A method of improving the air sealing effectiveness between a rotating component and a nonrotating component in a turbine engine, the rotating and nonrotating components being separated by a gap with knife edge seals extending across the gap to inhibit leakage of air therethrough, the method characterized by:
- a) providing a brush seal;
- b) reconfiguring the nonrotating component to provide means for receiving and retaining the brush seal in tandem with the knife edge seals; and
- c) installing the brush seal so that the seal bristles extend toward the rotating component to impede the flow of air through the gap the brush seal being retained by the receiving and retaining means.
24. The method of claim 3 wherein the nonrotating component is hollow and substantially cylindrical and has a wall thickness and a face, the method characterized in that the step of reconfiguring the nonrotating component includes:
- a) creating a capture slot in the face of the nonrotating component for radially retaining the brush seal; and
- b) attaching a retainer to the nonrotating component so that the retainer cooperates with the face to axially trap the brush seal.
25. The method of claim 4 characterized in that the reconfiguring step includes reducing the wall thickness by a predefined amount in the vicinity of the face to form a seal seat and accommodate the radial dimension of the brush seal.
26. The method of claim 4 characterized in that the reconfiguring step regulates the axial length of the nonrotating component.
27. The method of claim 3 wherein the brush seal is a multilayered brush seal.
28. The method of claim 3 wherein the nonrotating component comprises upper and lower component segments each component segment subtending approximately 180 degrees of arc, the retainer also comprises upper and lower retainer segments, each retainer segment subtending approximately 180 degrees of arc, and the brush seal comprises an upper brush seal segment subtending approximately 180 degrees of arc and one or more lower brush seal segments, the lower brush seal segments collectively subtending approximately 180 degrees of arc.
29. A method of improving the air sealing effectiveness between a rotating component and a nonrotating component in a turbine engine, the nonrotating component being hollow and substantially cylindrical and having a wall thickness and a face, the rotating and nonrotating components being separated by a gap with knife edge seals extending across the gap to inhibit leakage of air therethrough, the method characterized by:
- a) reconfiguring the nonrotating component by reducing its axial length by a predetermined amount and reducing its wall thickness in the vicinity of the face by a predefined amount whereby a seal seat is formed;
- b) creating an axially and circumferentially extending capture slot in the face of the nonrotating component;
- c) attaching a retainer to the face so that the retainer cooperates with the face and the seal seat to define a circumferentially extending groove;
- d ) installing a brush seal in the groove so that the bristles of the seal extend toward the rotating component to impede the flow of air through the gap; and,
- e) the brush seal being radially retained by the capture slot and the seal seat and axially retained by the retaining ring and the face.
Type: Application
Filed: Jan 13, 2005
Publication Date: Mar 30, 2006
Applicant:
Inventor: Steve Ingistov (Los Angeles, CA)
Application Number: 11/034,563
International Classification: F02C 7/28 (20060101);