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EP-4739889-A1 - STATOR DIAPHRAGM WITH SEAL RING, STEAM TURBINES AND POWER PLANTS INCLUDING STATOR DIAPHRAGM AND METHODS FOR ARRANGING SEAL RINGS IN STATOR DIAPHRAGMS

EP4739889A1EP 4739889 A1EP4739889 A1EP 4739889A1EP-4739889-A1

Abstract

The present disclosure relates to a stator diaphragm comprising a diaphragm body including a radially outer ring, a radially inner ring and a plurality of stator vanes extending between the radially outer ring and the radially inner ring. The diaphragm body further comprises an axial seal face and a circular groove at the axial seal face. The stator diaphragm further comprises a seal ring and a plurality of spacers arranged in the circular groove, and the spacers axially position the seal ring in the circular groove. The present disclosure further relates to steam turbines comprising such stator diaphragms, to power plants comprising said steam turbines, and to methods for arranging a seal ring between a seal face of a stator diaphragm and a stationary part of a steam turbine.

Inventors

  • MENDEZ PULIDO, Fernando
  • AZCARATE CASTRELLÓN, Martha Alejandra
  • CORONA BRAVO, Cesar

Assignees

  • GE Vernova Technology GmbH

Dates

Publication Date
20260513
Application Date
20230823

Claims (18)

  1. 1. A stator diaphragm comprising a diaphragm body including a radially outer ring, a radially inner ring and a plurality of stator vanes extending between the radially outer ring and the radially inner ring, wherein the diaphragm body comprises an axial seal face and a circular groove at the axial seal face, and further comprising: a seal ring and a plurality of spacers arranged in the circular groove, wherein the spacers axially position the seal ring in the circular groove.
  2. 2. The stator diaphragm of claim 1 , wherein the plurality of spacers is arranged in a plurality of holes circumferentially distributed along the circular groove.
  3. 3. The stator diaphragm of any of claims 1 - 2, wherein the spacers are selected from a group including dowels, pins, bolts, and screws.
  4. 4. The stator diaphragm of claim 3, wherein the bolts or screws extend through the seal ring.
  5. 5. The stator diaphragm of any of claims 1 - 4, wherein the spacers have an axial length, and the axial length of the spacers determines the position of the seal ring.
  6. 6. The stator diaphragm of any of claims 1 - 5, wherein the circular groove is arranged at the axial seal face of the radially outer ring.
  7. 7. The stator diaphragm of any of claims 1 - 6, wherein the axial seal face of the stator diaphragm is at a low pressure side of the stator diaphragm.
  8. 8. The stator diaphragm of any of claims 1 - 7, wherein the seal ring is composed of a plurality of seal segments.
  9. 9. A steam turbine comprising the stator diaphragm of any of claims 1 - 8, wherein the steam turbine is at least one from a reaction turbine, an impulse turbine, an axial turbine, and a radial turbine.
  10. 10. The steam turbine of claim 9, wherein the seal ring of the stator diaphragm is configured to provide a sealing between the stator diaphragm and a stationary part of the steam turbine, and wherein the stationary part of the steam turbine comprises a plurality of secondary spacers, such that the seal ring is arranged between the spacers of the stator diaphragm and the secondary spacers.
  11. 11 . A fossil, renewable-energy, waste-to-energy, combined-cycle or nuclear power plant comprising the steam turbine of any of claims 9 - 10.
  12. 12. A method for arranging a seal ring between a seal face of a stator diaphragm and a stationary part of a turbine, comprising: providing a circular groove at the seal face; arranging a plurality of spacers in the circular groove; and arranging the seal ring in the circular groove, wherein the spacers axially position the seal ring in the circular groove.
  13. 13. The method of claim 12, wherein providing a circular groove comprises machining the circular groove.
  14. 14. The method of claim 13, further comprising removing an existing seal ring prior to machining the circular groove.
  15. 15. The method of any of claims 12 - 14, wherein arranging a plurality of spacers in the circular groove includes: drilling a plurality of holes along the circular groove, and arranging the plurality of spacers in the plurality of holes.
  16. 16. The method of any of claims 12 - 16, wherein arranging the seal ring in the circular groove comprises arranging at least one segment of the seal ring in the circular groove.
  17. 17. The method of any of claims 12 - 17, further comprising: removing the seal ring; replacing one or more of the spacers with differently sized spacers; and positioning the seal ring in the circular groove.
  18. 18. The method of any of claims 12 - 18, further comprising: replacing the seal ring with differently sized seal ring; and positioning the differently sized seal ring in the circular groove 19. The stator diaphragm of any of claims 1 - 8 or the method of any of claims 12 - 18, wherein the seal ring is made of austenitic steel.

Description

STATOR DIAPHRAGM WITH SEAL RING, STEAM TURBINES AND POWER PLANTS INCLUDING STATOR DIAPHRAGM AND METHODS FOR ARRANGING SEAL RINGS IN STATOR DIAPHRAGMS TECHNICAL FIELD [0001 ] The present disclosure relates to seals and sealing of stator diaphragms for turbines, particularly for steam turbines. The present disclosure further relates to steam turbines as well as to power plants comprising such stator diaphragms. The present disclosure further particularly relates to methods of adaptation of axial clearances for stator diaphragms. BACKGROUND [0002] Steam turbines are rotary mechanical devices that generate mechanical energy from steam that flows through the turbine. For example, electrical power may be generated when the turbine is connected to a generator. A steam turbine comprises a rotor which includes a shaft and a plurality of rows of rotor blades. A row of blades may also be known as wheel. The shaft is arranged along an axial direction of the turbine, and the plurality of rows of blades is connected to the shaft. The rotor is supported by bearings and is housed in a casing, e.g. a cylinder-shaped casing. [0003] A plurality of nozzles (also known as stator blades) may be fixed with respect to the casing and form part of a stator. The nozzles may also be called “vanes” and may be directly or indirectly attached to the casing. A row of vanes indirectly connected to a casing is herein called a "diaphragm". A stator diaphragm may be regarded herein as a disc-shaped device including a row of vanes. The nozzles are arranged between the rows of rotor blades in a turbine. The interaction between the nozzles and the rotor blades is responsible for rotation of a turbine. The casing and the nozzles form the stationary parts of the steam turbine. [0004] A pair of a row of nozzles and a subsequent row of rotor blades is usually referred to as a stage of a turbine. A steam turbine typically comprises a plurality of stages. A steam turbine may comprise sections which operate at different pressures. Turbine sections are also known as cylinders. A steam turbine may for example comprise at least one of a high-pressure (HP) section, an intermediate pressure (IP) section and a low-pressure (LP) section. [0005] During operation of the steam turbine, the nozzles have a fixed position. They direct the flow of steam that is between a preceding rotor blade row and the next rotor blade row. Rows of rotor blades are designed to turn as the steam passes through them. The rotation of the rows turns the shaft to which they are attached. And the shaft may for example turn a generator for producing electric power. [0006] Steam may be provided at a high pressure side of a steam turbine through a steam inlet. The steam may then expand along the various stages of the turbine. In order to ensure that the steam follows the intended path, several sealings are provided, both in relation with the rotor blades and in relation with the stator blades. Such sealings may be configured to avoid any fluid (steam) loss in varying operational conditions, e.g. with varying pressure and temperature and thus are to provide appropriate sealing regardless of (thermal) expansion of parts. In particular, a seal ring is provided at an axial face of the diaphragm, e.g. between two neighboring stator diaphragms. This face is also known as an axial seal face. The other face of the diaphragm that is upstream (high-pressure side) is called a forward face. A seal ring can also seal a space between a stator diaphragm and a casing. Such a seal ring extends along the circumference of a stator diaphragm. [0007] In order to provide appropriate axial clearance between rotor blades and stator blades, it is necessary to precisely machine a face of the stator diaphragm to properly align rotor blades and stator blades. In essence, this machining is needed to be able to fit a stator diaphragm into a casing and to allow said stator diaphragm to work with other elements of a turbine. Such machining requires a significant amount of time and is technologically challenging. It is also not done at a power plant, but at a specialized machine shop that has capabilities to perform said machining. It may be the case that, after an installation attempt, further machining is required. It follows that a stator diaphragm has to be taken from a power plant to a machine shop which impacts the time of servicing or upgrading a steam turbine. This also means that said stator diaphragm, especially for older machines, has to be transported even multiple times between a power plant and a shop before the steam turbine will finally be assembled with a proper axial clearance. [0008] The present disclosure provides examples of methods, stator diaphragms, steam turbines and power plants that allow for adjustment of clearance with reduction or elimination at least some of the aforementioned problems. Specific examples pursue at least one of avoiding the need to transport multiple times a stator diaphrag