US20120308360A1

US20120308360A1 - Overlap seal for turbine nozzle assembly

Info

Publication number: US20120308360A1
Application number: US13/118,686
Authority: US
Inventors: Fred Thomas Willett, JR.
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 2011-05-31
Filing date: 2011-05-31
Publication date: 2012-12-06
Also published as: FR2976019A1; RU2012122108A; DE102012104620A1

Abstract

Systems for thermally regulating portions of a turbine are disclosed. In one embodiment, a turbine nozzle assembly includes: an outer diaphragm ring; a vane physically connected to the outer diaphragm ring; and an inner diaphragm ring physically connected to the vane, the inner diaphragm ring including a first axial tooth configured to interact and substantially form a seal with a second axial tooth disposed on a bucket shank.

Description

BACKGROUND OF THE INVENTION

The subject matter disclosed herein relates to turbines and, more particularly, to overlap seals for a turbine drum rotor cooling circuit.
Some power plant systems, for example certain nuclear, simple cycle and combined cycle power plant systems, employ turbines in their design and operation. Some of these turbines are driven by a flow of high temperature steam which is directed over the buckets/blades of the turbine. This high temperature steam can have detrimental effects on the condition and longevity of certain components in the turbine such as a drum rotor. Repeated exposure of the drum rotor to high temperature steam may result in inefficient operation, corrosion, system damage, and a need for rotor repairs and/or rotor replacement. Some systems attempt to adapt the drum rotor to tolerate contact with high temperature steam in order to avoid shortening the lifespan of the drum rotor. In these systems, the drum rotor design and build process includes specific, temperature-resistant materials which are intended to allow the rotor to operate in contact with high temperature steam without significant degradation. However, these specific, temperature-resistant materials may be expensive, contributing to increased overall system cost. Further, use of these materials may complicate the design and build process.

BRIEF DESCRIPTION OF THE INVENTION

Devices for shielding and cooling turbine components are disclosed. In one embodiment, a turbine nozzle assembly includes: an outer diaphragm ring; a vane physically connected to the outer diaphragm ring; and an inner diaphragm ring physically connected to the vane, the inner diaphragm ring including a first axial tooth configured to interact and substantially form a seal with a second axial tooth disposed on a bucket shank.
A first aspect of the disclosure provides a turbine nozzle assembly including: an outer diaphragm ring; a vane physically connected to the outer diaphragm ring; and an inner diaphragm ring physically connected to the vane, the inner diaphragm ring including a first axial tooth configured to interact and substantially form a seal with a second axial tooth disposed on a bucket shank.
A second aspect provides a turbine bucket including: a blade; and a bucket shank coupled to the blade, wherein the bucket shank includes a first axial tooth configured to extend toward a nozzle, substantially forming a seal with the nozzle.
A third aspect provides a turbine including: a stator; a working fluid passage substantially surrounded by the stator; a drum rotor configured radially inboard of the working fluid passage; a cooling circuit fluidly connected to the drum rotor; and an overlap seal disposed between a nozzle coupled to the stator and a turbine bucket coupled to the drum rotor, the overlap seal substantially fluidly separating the working fluid passage and the cooling circuit, the overlap seal including: a first axial tooth disposed upon the nozzle; and a second axial tooth disposed upon the turbine bucket, the second axial tooth being configured to interact and substantially form a seal with the first axial tooth.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features of this invention will be more readily understood from the following detailed description of the various aspects of the invention taken in conjunction with the accompanying drawings that depict various embodiments of the invention, in which:

FIG. 1 shows a partial cut-away schematic view of a turbine system according to an embodiment of the invention.

FIG. 2 shows a partial cut-away schematic view of a turbine system according to an embodiment of the invention.

FIG. 3 shows a partial cut-away schematic view of portions of a turbine system according to an embodiment of the invention.

FIG. 4 shows a three-dimensional perspective view of a turbine bucket according to an embodiment of the invention.

FIG. 5 shows a partial cut-away schematic view of portions of a turbine system according to an embodiment of the invention.

FIG. 6 shows a partial cut-away schematic view of a nozzle and turbine bucket according to an embodiment of the invention.

FIG. 7 shows a partial cut-away schematic view of an embodiment of a nozzle and turbine bucket in accordance with an aspect of the invention.

FIG. 8 shows a partial cut-away schematic view of an embodiment of a nozzle and turbine bucket in accordance with an aspect of the invention.

FIG. 9 shows a partial cut-away schematic view of an embodiment of a nozzle and turbine bucket in accordance with an aspect of the invention.

FIG. 10 shows a schematic block diagram illustrating portions of a combined cycle power plant system according to embodiments of the invention.

FIG. 11 shows a schematic block diagram illustrating portions of a single-shaft combined cycle power plant system according to embodiments of the invention.

It is noted that the drawings of the disclosure are not necessarily to scale. The drawings are intended to depict only typical aspects of the disclosure, and therefore should not be considered as limiting the scope of the disclosure. In the drawings, like numbering represents like elements between the drawings.

DETAILED DESCRIPTION OF THE INVENTION

Some turbines include static nozzle assemblies that direct flow of a working fluid into turbine buckets connected to a rotating drum rotor. The turbine buckets include bucket shanks and blades (airfoils) and the nozzle assembly includes a plurality of nozzles, “vanes” or “airfoils” and is sometimes referred to as a “diaphragm” or “nozzle assembly stage.” Steam turbine diaphragms include two rings, the outer diaphragm ring and the inner diaphragm ring. These two rings are separated by and coupled to one another via a plurality of vanes. The nozzle assembly is typically comprised of two halves, one upper and one lower, each containing an inner ring, an outer ring, and a plurality of vanes. The upper and lower halves are assembled around the rotor.
As indicated above, aspects of the invention provide for systems and devices configured to thermally protect portions of a turbine from damage due to contact with a turbine working fluid (e.g., high temperature steam) by using overlap seals and a cooling circuit. The cooling circuit supplies a cooling fluid (e.g., low temperature steam) to the drum rotor. The low temperature steam travels through the drum rotor via the cooling circuit which is defined in part by axial passages through the turbine buckets, and overlap seals which are disposed between nozzles and turbine buckets in the turbine. The overlap seals substantially blocking the axial gap between bucket platforms and nozzle root bands and restricting radially inward or outward flows.
In the art of power generation systems (including, e.g., nuclear reactors, steam turbines, gas turbines, etc.), turbines driven by high temperature steam are often employed as part of the system. The high temperature steam is directed through multiple sets of turbine buckets, thereby rotating a drum rotor and converting thermal energy into mechanical energy. Typically, as the temperature of the steam is increased, so too is the efficiency of the overall power generation system. However, the high temperature steam may have negative effects on certain components of the turbine such as the drum rotor. The high temperature of the steam can cause material damage to the drum rotor, increasing the maintenance cost of the system and significantly reducing the lifespan of the drum rotor.
Turning to the FIGURES, embodiments of a cooling circuit including overlap seals are shown, where the cooling circuit may impact the efficiency and increase the life expectancy of the drum rotor, the turbine and the overall power generation system by cooling the drum rotor and shielding the drum rotor from contact with a working fluid (e.g., high temperature steam). Each of the components in the FIGURES may be connected via conventional means, e.g., via a common conduit or other known means as is indicated in FIGS. 1-11. Specifically, referring to FIG. 1, a partial cross-sectional view of a turbine 100 is shown according to embodiments of the invention. Turbine 100 may include a drum rotor 10 (partially shown in FIG. 1) and a stator 15 (partially shown in FIG. 1) substantially surrounding drum rotor 10. Drum rotor 10 may include at least one substantially circumferential dovetail slot 40 along its outer circumference. A turbine bucket 12 may be secured within at least one substantially circumferential dovetail slot 40 on drum rotor 10. Drum rotor 10 may include a plurality of substantially circumferential dovetail slots 40 and a plurality of turbine buckets 12 secured therein as is known in the art.
Stator 15 may include at least one nozzle 17 secured within a nozzle slot 19. As seen in FIG. 1, stator 15 may include a plurality of nozzles 17 which define stages of the turbine and may be secured within nozzle slots 19. Nozzles 17 and turbine buckets 12 may radially extend respectively from stator 15 and drum rotor 10, such that nozzles 17 and turbine buckets 12 are interspersed along an axial length of turbine 100. A working fluid, such as steam, may be directed to a downstream location 14, along primary working fluid passage 5 through turbine buckets 12 and nozzles 17 to assist the rotation of drum rotor 10.
Turning to FIG. 2, a schematic partial cut-away side-view of a turbine 200 including an overlap seal 207 is shown according to embodiments. It is understood that elements similarly numbered between FIG. 1 and FIG. 2 may be substantially similar as described with reference to FIG. 1. Further, in embodiments shown and described with reference to FIGS. 2-11, like numbering may represent like elements. Redundant explanation of these elements has been omitted for clarity. Finally, it is understood that the components of FIGS. 1-11 and their accompanying descriptions may be applied to any embodiment described herein.
Returning to FIG. 2, in this embodiment, turbine 200 may include a packing head 210. A cooling fluid may be introduced into turbine 200 through a cooling circuit 7 via a snout 202 in packing head 210. The fluid introduced through cooling circuit 7 may include steam or any other fluid as is known in the art. Snout 202 may be configured to supply fluid to an annulus 206 via coolant delivery passages 204. In one embodiment, packing head 210 may include a plurality of snouts 202 configured to introduce cooling fluid into turbine 200 via cooling circuit 7. In one embodiment, packing head 210 may include a single coolant delivery passage 204. In one embodiment, coolant delivery passages 204 may be configured as straight radially extending passages. In another embodiment, coolant delivery passages 204 may be configured as a tortuous set of passages. In any event, cooling circuit 7 may direct a fluid to annulus 206 via snout 202 and coolant delivery passages 204. From annulus 206, cooling circuit 7 directs the fluid through drum rotor 10. In drum rotor 10, cooling circuit 7 is further defined by overlap seal 207 disposed between turbine bucket 12 and nozzle 17. Overlap seal 207 is configured to shield drum rotor 10 from fluid and/or thermal contact with a working fluid passage 5 and to fluidly separate working fluid passage 5 and cooling circuit 7.
Turning to FIG. 3, a partial cut-away of an embodiment of a turbine 300 is shown having cooling circuit 7 partially defined by a plurality of overlap seals 207 and a set of axial passages 302 (shown in phantom) formed through turbine bucket shanks 502. In this embodiment, axial passages 302 may be fluidly connected to cooling circuit 7, allowing fluid to pass from annulus 206 through multiple stages of turbine 300 via axial passages 302. The plurality of overlap seals 207 disposed on a turbine bucket shank 502 of turbine bucket 12 and an inner diaphragm ring 507 of nozzle 17. Plurality of overlap seals 207 further defining cooling circuit 7, shielding rotor 10 from working fluid passage 5 and separating working fluid passage 5 and cooling circuit 7. In one embodiment, cooling circuit 7 may pass through a set of nozzle root seals 304 disposed between rotor 10 and nozzles 17. In one embodiment, cooling circuit 7 may be pressurized such that a positive pressure differential is created relative to working fluid passage 5. In another embodiment, working fluid passage 5 may be pressurized such that a positive pressure differential is created relative to cooling circuit 7. In one embodiment, a fluid passing through cooling circuit 7 may be at a low temperature relative to a fluid passing through working fluid passage 5. In one embodiment, after passing through a set of stages in turbine 300 via axial passages 302, cooling circuit 7 may exhaust the cooling fluid into working fluid passage 5.
Turning to FIG. 4, a partial three-dimensional perspective of an environment 400 including an embodiment of a turbine bucket shank 502 is shown having a set of axial passages 302 there through. Axial passages 302 enable the passing of a fluid through a plurality of stages in a turbine. In one embodiment, axial passages 302 may be machined into bucket shank 502. In another embodiment, axial passages 302 may be formed in bucket shank 502. In another embodiment, axial passages 302 may be fluidly connected to cooling circuit 7.
Turning to FIG. 5, a partial cut-away of a portion of an embodiment of a turbine 500 is shown having axial teeth 508 disposed upon an inner diaphragm ring 507 of nozzle 17 and axial teeth 509 disposed upon a bucket shank 502 of turbine bucket 12. In this embodiment, axial teeth 508 extend toward bucket shank 502 such that axial teeth 508 overlap and interact with axial teeth 509 which extend toward inner diaphragm ring 507, thereby forming a plurality of overlap seals 207. Plurality of overlap seals 207, partially define cooling circuit 7 along with axial passage 302 (shown in phantom) and an axial passage 510 (shown in phantom). In this embodiment, turbine bucket 12 includes bucket shank 502 and a blade 504. Nozzle 17 includes an outer diaphragm ring 505, inner diaphragm ring 507 and a nozzle vane 503. In this embodiment, overlap seals 207 substantially fluidly separate working fluid passage 5 and cooling circuit 7 which is radially inboard of working fluid passage 5 and passes below axial teeth 508 and 509, and through axial passages 302 and 510. In one embodiment, cooling circuit 7 may be exhausted into working fluid passage 5 via axial passage 510. In one embodiment, nozzle vane 503 may have a height between about 1 inch and about 2 inches, and a width between about 1 inch and about 2 inches. In another embodiment, nozzle vane 503 may have a height between about 2 inches and about 3 inches, and a width between about 2 inches and about 3 inches. In one embodiment, nozzle vanes 503 may be circumferentially spaced between about 0.2 inches and about 0.7 inches relative one another.
Turning to FIG. 6, a partial cut-away view of an embodiment of a nozzle 17 and set of turbine buckets 12 is shown having a plurality of axial teeth 508 and 509. In this embodiment, two axial teeth 508 disposed on inner diaphragm ring 507 may be configured between two axial teeth 509 disposed on bucket shank 502 so as to interact and form overlap seals 207. In one embodiment, overlap seal 207 may be comprised of any number of axial teeth 508 and 509. Overlap seal 207 with axial passages 302, partially defining cooling circuit 7 which may flow through nozzle root seals 304.
Turning to FIG. 7, a partial cut-away of an embodiment of a nozzle 17 and set of turbine buckets 12 is shown having axial teeth 508 configured relative to axial teeth 509 so as to form overlap seals 207. In this embodiment, axial teeth 508 disposed on inner diaphragm ring 507 include a radially extending tip portion 808. Radially extending tip portion 808 further reducing a clearance between axial teeth 508 and 509, and substantially forming a seal there between. Turning to FIG. 8, a partial cut-away view of an embodiment of a nozzle 17 and set of turbine buckets 12 is shown having axial teeth 508 configured relative to axial teeth 509 so as to form overlap seals 207. In this embodiment, axial teeth 509 disposed on bucket shanks 502 include a radially extending tip portion 809. Radially extending tip portion 809 further reducing a clearance between axial teeth 508 and 509, and substantially forming a seal there between. Turning to FIG. 9, a partial cut-away view of an embodiment of a nozzle 17 and set of turbine buckets 12 is shown having axial teeth 508 configured relative to axial teeth 509 so as to form overlap seals 207. In this embodiment, axial teeth 508 include a radially extending tip portion 808 and axial teeth 509 include a radially extending tip portion 809. Radially extending tip portions 808 and 809 further reducing a clearance between axial teeth 508 and 509, and substantially forming a seal there between.
Turning to FIG. 10, a schematic view of portions of a multi-shaft combined cycle power plant 900 is shown. Combined cycle power plant 900 may include, for example, a gas turbine 902 operably connected to a generator 908. Generator 908 and gas turbine 902 may be mechanically coupled by a shaft 907, which may transfer energy between a drive shaft (not shown) of gas turbine 902 and generator 908. Also shown in FIG. 10 is a heat exchanger 904 operably connected to gas turbine 902 and a steam turbine 906. Heat exchanger 904 may be fluidly connected to both gas turbine 902 and a steam turbine 906 via conventional conduits (numbering omitted). Gas turbine 902 and/or steam turbine 906 may be fluidly connected to cooling circuit 7 of FIG. 3 or other embodiments described herein. Heat exchanger 904 may be a conventional heat recovery steam generator (HRSG), such as those used in conventional combined cycle power systems. As is known in the art of power generation, HRSG 904 may use hot exhaust from gas turbine 902, combined with a water supply, to create steam which is fed to steam turbine 906. Steam turbine 906 may optionally be coupled to a second generator system 908 (via a second shaft 907). It is understood that generators 908 and shafts 907 may be of any size or type known in the art and may differ depending upon their application or the system to which they are connected. Common numbering of the generators and shafts is for clarity and does not necessarily suggest these generators or shafts are identical. In one embodiment (shown in phantom), cooling circuit 7 may receive a fluid from HRSG 904. In another embodiment, cooling circuit 7 may receive a fluid from steam turbine 906. In one embodiment of the present invention (shown in phantom), cooling circuit 7 receives a fluid from a fluid source 909. Fluid source 909 may be a compressor, pressurized gas source or other fluid source as is known in the art. In another embodiment (shown in phantom), cooling circuit 7 may receive a fluid in the form of compressed air generated from the operation of gas turbine 902. In another embodiment, steam turbine 906 may be fluidly integrated with cooling circuit 7. In another embodiment, shown in FIG. 11, a single shaft combined cycle power plant 990 may include a single generator 908 coupled to both gas turbine 902 and steam turbine 906 via a single shaft 907. Steam turbine 906 and/or gas turbine 902 may be fluidly connected to cooling circuit 7 of FIG. 3 or other embodiments 200, 400, 500, 600, 700, 800 or 900 described herein.
The overlap seals and cooling circuit of the present disclosure are not limited to any one particular turbine, power generation system or other system, and may be used with other power generation systems and/or systems (e.g., combined cycle, simple cycle, nuclear reactor, etc.). Additionally, the overlap seals and cooling circuit of the present invention may be used with other systems not described herein that may benefit from the thermal protection of the cooling circuit described herein.
The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the disclosure. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” and/or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.
This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.

Claims

1. A turbine nozzle assembly comprising:

an outer diaphragm ring;

a vane physically connected to the outer diaphragm ring; and

an inner diaphragm ring physically connected to the vane, the inner diaphragm ring including a first axial tooth configured to interact and substantially form a seal with a second axial tooth disposed on a bucket shank.

2. The turbine nozzle assembly of claim 1, wherein the inner diaphragm ring includes a first plurality of axial teeth configured to interact and substantially form a seal with a second plurality of axial teeth disposed on the bucket shank.

3. The turbine nozzle assembly of claim 1, wherein the first axial tooth includes a radially extending tip portion, the radially extending tip portion being configured to extend toward the second axial tooth.

4. The turbine nozzle assembly of claim 1, wherein the second axial tooth includes a radially extending tip portion, the radially extending tip portion being configured to extend toward the first axial tooth.

5. The turbine nozzle assembly of claim 4, wherein the first axial tooth includes a radially extending tip portion, the radially extending tip portion being configured to extend toward the second axial tooth.

6. The turbine nozzle assembly of claim 1, wherein the first axial tooth and the second axial tooth are configured to substantially fluidly separate two portions of a turbine, enabling a pressure differential to be maintained there between.

7. A turbine bucket comprising:

a blade; and

a bucket shank coupled to the blade, wherein the bucket shank includes a first axial tooth configured to extend toward a nozzle, substantially forming a seal with the nozzle.

8. The turbine bucket of claim 7, wherein the bucket shank includes a first plurality of axial teeth configured to interact and substantially form a seal with a second plurality of axial teeth disposed on the nozzle.

9. The turbine bucket of claim 7, wherein the first axial tooth includes a radially extending tip portion, the radially extending tip portion being configured to extend toward a second axial tooth disposed on the nozzle.

10. The turbine bucket of claim 9, wherein the second axial tooth includes a radially extending tip portion, the radially extending tip portion being configured to extend toward the first axial tooth.

11. The turbine bucket of claim 10, wherein the first axial tooth and the second axial tooth are configured to substantially fluidly separate two portions of a turbine, enabling a pressure differential to be maintained there between.

12. A turbine, comprising:

a stator;

a working fluid passage substantially surrounded by the stator;

a drum rotor configured radially inboard of the working fluid passage;

a cooling circuit fluidly connected to the drum rotor; and

an overlap seal disposed between a nozzle coupled to the stator and a turbine bucket coupled to the drum rotor, the overlap seal substantially fluidly separating the working fluid passage and the cooling circuit, the overlap seal comprising:

a first axial tooth disposed upon the nozzle; and

a second axial tooth disposed upon the turbine bucket, the second axial tooth being configured to interact and substantially form a seal with the first axial tooth.

13. The turbine of claim 12, further comprising a packing head including a coolant delivery passage fluidly connected to the cooling circuit and a snout disposed within the packing head, wherein the coolant delivery passage is configured to obtain a fluid from the snout and channel the fluid to the cooling circuit.

14. The turbine of claim 12, wherein the cooling circuit includes a pressurized fluid, the pressurized fluid creating a positive pressure differential in the cooling circuit with respect to the working fluid passage.

15. The turbine of claim 12, wherein the turbine bucket includes an axial passage fluidly connected to the cooling circuit.

16. The turbine of claim 12, wherein the turbine bucket includes a first plurality of axial teeth configured to interact and substantially form a seal with a second plurality of axial teeth disposed on the nozzle.

17. The turbine of claim 12, wherein the first axial tooth includes a radially extending tip portion, the radially extending tip portion being configured to extend toward the second axial tooth.

18. The turbine of claim 12, wherein the second axial tooth includes a radially extending tip portion, the radially extending tip portion being configured to extend toward the first axial tooth.

19. The turbine of claim 18, wherein the first axial tooth includes a radially extending tip portion, the radially extending tip portion being configured to extend toward the second axial tooth.

20. The turbine of claim 12, further comprising a plurality of overlap seals disposed between a plurality of nozzles and a plurality of turbine buckets.