Tuning thermal mismatch between turbine rotor parts with a thermal medium

• US 6,190,127 B1
• Filed: 12/22/1998
• Issued: 02/20/2001
• Est. Priority Date: 12/22/1998
• Status: Expired due to Term

• Current Assignee: General Electric Company
• Original Assignee: General Electric Company
• Inventors: Schmidt, Mark Christopher
• Primary Examiner(s): VERDIER, CHRISTOPHER M
• Application Number:
  US09/218,230
• Time in Patent Office: 791 Days
• Field of Search: 415/47, 415/48, 415/115, 415/116, 415/117, 415/175-178, 415/134, 415/136, 415/138, 416/39, 416/95, 416/96.R, 416/96.A, 416/97.R, 416/198.A, 416/200.A, 416/201.R
• US Class Current: 416/95
• CPC Class Codes: F01D 5/082 on the side of the rotor disc
• CPC Class Codes: F01D 5/088 in a closed cavity

Abstract

In a turbine rotor, an aft shaft wheel and the final-stage wheel of the rotor are coupled together, including by a rabbeted joint. During shutdown and startup of the turbine, a thermal mismatch between the aft shaft wheel and final-stage wheel is avoided by respectively heating and cooling the aft shaft wheel to maintain the thermal mismatch within acceptable limits, thereby avoiding opening of the rabbeted joint and the potential for unbalancing the rotor and rotor vibration. The thermal medium may be supplied by piping in the aft bearing cavity into the cavity between the forward closure plate and the aft shaft wheel.

Claims

1. In a gas turbine having a pair of parts responsive to different applied temperatures creating a transient thermal mismatch, said turbine including a turbine rotor wheel for mounting buckets and an adjoining wheel having a rabbeted joint between registering faces thereof, a method of maintaining the thermal mismatch between said parts within a predetermined thermal mismatch, comprising the steps of:

flowing a fluid medium along a surface of one of said parts to either heat or cool said one part to a temperature enabling the magnitude of the thermal mismatch of said parts to lie within said predetermined thermal mismatch; and

flowing the fluid medium along a face of the adjoining wheel axially remote from the turbine rotor wheel to reduce the thermal mismatch to within said predetermined thermal mismatch to preclude relative displacement of elements forming the rabbeted joint.

2. A method according to claim 1 including starting the turbine by flowing hot gases of combustion through the turbine, causing an increased thermal mismatch between said parts, and flowing a cooling medium along said one surface to maintain the thermal mismatch between said parts to within said predetermined thermal mismatch.

3. A method according to claim 1 including shutting down the turbine by terminating flow of hot gases of combustion through the turbine thereby causing an increased thermal mismatch between said parts, and flowing a heating medium along said one surface to maintain the thermal mismatch between said parts to within said predetermined thermal mismatch.

4. A method according to claim 1 including starting the turbine by flowing hot gases of combustion through the turbine thereby causing an increased thermal mismatch between said parts and flowing a cooling medium along said one surface to maintain the thermal mismatch between said parts to within said predetermined thermal mismatch, operating the turbine at steady-state, and shutting down the turbine by terminating flow of hot gases of combustion through the turbine thereby causing an increased thermal mismatch between said parts and flowing a heating medium along said one surface to maintain the thermal mismatch between said parts to within said predetermined thermal mismatch.