Method and apparatus for eliminating thermal bowing of steam turbine rotors

• US 6,168,377 B1
• Filed: 01/27/1999
• Issued: 01/02/2001
• Est. Priority Date: 01/27/1999
• Status: Expired due to Fees

• Current Assignee: General Electric Company
• Original Assignee: General Electric Company
• Inventors: Marks, Paul Thomas, Rentz, Lawrence Edward, Carr, Roger Jordan, Turnquist, Norman Arnold, Wolfe, Christopher Edward, Baily, Frederick George, Morson, Alexander
• Primary Examiner(s): Look, Edward K.
• Assistant Examiner(s): NGUYEN, NINH H
• Application Number:
  US09/238,257
• Time in Patent Office: 706 Days
• Field of Search: 415/173.3, 415/173.5, 415/173.4, 415/174.2, 415/174.4, 415/174.5, 415/176, 415/178, 415/230, 415/231
• US Class Current: 415/174.2
• CPC Class Codes: F01D 11/001 for sealing space between stator blade and rotor
• CPC Class Codes: F16J 15/3288 Filamentary structures, e.g. brush seals

Abstract

Brush seals are employed on steam turbine rotors without the risk of causing thermal rotor bowing and without compromising the sealing performance. In one form, a groove in the rotor has an insert in frictional contact with the brush seal. The non-uniform distribution of heat due to frictional contact between the brush seal and proud portions of the rotor is dissipated within the insert such that adjoining rotor portions are substantially uniformly heated without causing thermal bow. In a further form, a groove or grooves are provided in the rotor surface adjacent to the brush seal and maintain non-uniform heat distribution locally in the rotor without causing thermal bow of the rotor. In another form, a land projects radially outwardly of the rotor surface in contact with the brush seal. The non-uniform distribution of heat due to frictional contact between proud portions of the land and the brush seal dissipates into a uniform distribution of heat in the rotor proper to avoid thermal bowing. In a final form, the brush seal has frictional contact with bucket dovetail or wheel protrusions spaced radially outwardly of the rotor such that non-uniform distribution dissipates into a uniform distribution within the rotor.

Claims

1. In a steam turbine having a rotor and a non-rotating component about the rotor carrying a brush seal for sealing engagement with the rotor, a method of substantially eliminating bowing of the rotor resulting from circumferentially non-uniform distribution of heat about the rotor due to frictional contact between the brush seal and a proud portion of the rotor, comprising inhibiting circumferential non-uniform heat transfer to the rotor generated by frictional contact between the proud portion of the rotor and the brush seal, including providing a groove in the rotor at an axial location corresponding to an axial location of the brush seal and providing an insert in said groove for engaging the brush seal.

2. A method according to claim 1 including substantially uniformly heating said insert in a circumferential direction before substantially heating the rotor surrounding the groove to ensure substantial uniform circumferential distribution of heat from the insert to the rotor.

3. A method according to claim 1 including limiting the contact between said insert and a surface defining said groove to limit heat transfer from the insert to the rotor.

4. A method according to claim 3 including contacting said insert and said grooved surface at locations interrupted by non-contact portions between said insert and said grooved surface.

5. A method according to claim 1 including thermally insulating said insert and said grooved surface from one another.

6. In a steam turbine having a rotor and a non-rotating component about the rotor carrying a brush seal for sealing engagement with the rotor, a method of substantially eliminating bowing of the rotor resulting from circumferentially non-uniform distribution of heat about the rotor due to frictional contact between the brush seal and a proud portion of the rotor, comprising inhibiting circumferential non-uniform heat transfer to the rotor generated by frictional contact between the proud portion of the rotor and the brush seal, including providing a groove in the rotor at a location spaced axially from an axial location of the contact between the brush seal and the rotor, thereby distributing heat generated by the frictional contact between the rotor and the brush seal substantially uniformly about the rotor at locations radially inwardly of a base of said groove to prevent thermal bowing of the rotor.

7. In a steam turbine having a rotor and a non-rotating component about the rotor carrying a brush seal for sealing engagement with the rotor, a method of substantially eliminating bowing of the rotor resulting from circumferentially non-uniform distribution of heat about the rotor due to frictional contact between the brush seal and a proud portion of the rotor, comprising inhibiting circumferential non-uniform heat transfer to the rotor generated by frictional contact between the proud portion of the rotor and the brush seal, including providing grooves in the rotor at locations on opposite axial sides of the brush seal and spaced axially from the axial location of the contact between the brush seal and the rotor, thereby distributing heat generated by the frictional contact between the rotor and the brush seal substantially uniformly about the rotor at locations radially inwardly of bases of said grooves to prevent thermal bowing of the rotor.

8. A steam turbine comprising:

a rotor and a non-rotating component about the rotor;

a brush seal carried by said non-rotating component for sealing engagement with the rotor including a proud portion of the rotor; and

means for inhibiting circumferential non-uniform heat transfer to the rotor generated by frictional contact between the proud portion of the rotor and said brush seal whereby bowing of the rotor resulting from non-uniform distribution of heat about the rotor due to frictional contact between the brush seal and a proud portion of the rotor is eliminated wherein said inhibiting means includes a groove in the rotor at an axial location corresponding to an axial location of the brush seal and an insert in said groove for engaging the brush seal.

9. Apparatus according to claim 8 wherein said inhibiting means includes support elements between said insert and a surface defining said groove spacing said insert from said groove surface thereby thermally insulating said insert and said groove surface from one another.

10. A steam turbine comprising:

a rotor and a non-rotating component about the rotor;

a brush seal carried by said non-rotating component for sealing engagement with the rotor including a proud portion of the rotor; and

means for inhibiting circumferential non-uniform heat transfer to the rotor generated by frictional contact between the proud portion of the rotor and said brush seal whereby bowing of the rotor resulting from non-uniform distribution of heat about the rotor due to frictional contact between the brush seal and a proud portion of the rotor is eliminated, wherein said inhibiting means includes a groove in the rotor at a location spaced axially from an axial location of the engagement between the brush seal and the rotor, whereby heat generated by frictional contact between the rotor and the brush seal is distributed substantially uniformly about the rotor at locations radially inwardly of a base of said groove to prevent thermal bowing of the rotor.

11. Apparatus according to claim 10 including a second groove in the rotor at a location on an opposite side of the brush seal from the first-mentioned groove and spaced axially from the axial location of the engagement between the brush seal and the rotor.

12. A steam turbine comprising:

a rotor and a non-rotating component about the rotor;

a brush seal carried by said non-rotating component for sealing engagement with the rotor including a proud portion of the rotor;

means for inhibiting circumferential non-uniform heat transfer to the rotor generated by frictional contact between the proud portion of the rotor and said brush seal whereby bowing of the rotor resulting from non-uniform distribution of heat about the rotor due to frictional contact between the brush seal and a proud portion of the rotor is eliminated, said inhibiting means including a rib circumferentially about and projecting radially outwardly of said rotor for engagement with the brush seal and at least one axially extending flange on said projecting rib for distributing heat generated by said frictional contact substantially uniformly about said rotor.

13. A steam turbine comprising:

a rotor and a non-rotating component about the rotor;

a brush seal carried by said non-rotating component for sealing engagement with the rotor including a proud portion of the rotor; and

means for inhibiting circumferential non-uniform heat transfer to the rotor generated by frictional contact between the proud portion of the rotor and said brush seal whereby bowing of the rotor resulting from non-uniform distribution of heat about the rotor due to frictional contact between the brush seal and a proud portion of the rotor is eliminated;

said rotor including a plurality of buckets having bucket dovetails for connection with complementary dovetails on a wheel of said rotor said inhibiting means including an axial extending protrusion on each said turbine bucket dovetail in frictional engagement with said brush seal, said axial protrusion being outwardly of the dovetail connections between the bucket dovetails and the rotor wheel.