Turbine Nozzle Assembly Using Temporary Support Pedestal
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Solution Overview
Problem
The existing methods for assembling nozzle rings between buckets in a gas turbine are inefficient, often requiring disassembly of rotor wheels, leading to potential mechanical damage and unbalancing, with asymmetry and deformation issues due to split casing assemblies.
Innovation Solution
A method and apparatus that temporarily fix nozzles to the rotor during assembly, using a main pedestal with movable arched arms to position and secure the nozzles between buckets, allowing for precise assembly without disassembling rotor wheels, and preventing contact between stator and rotor components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If full ring casing is used to reduce clearances and avoid deformation, then manufacturing precision and reliability are improved, but device complexity increases and assembly difficulty worsens due to the need to unpack rotor wheels or disassemble bucket stages
Solution Approach 1:
The invention divides the casing into two separate halves (first casing and second casing) that can be assembled independently around the rotor without requiring disassembly of the rotor or bucket stages. This segmentation allows the nozzle ring to be installed between the rotor stages while maintaining the structural integrity and balance of the rotor assembly.
Solution Approach 2:
The invention introduces a temporary support mechanism as an intermediary device to hold the nozzle ring in place during assembly. This temporary support acts as a mediator between the nozzle ring and the rotor, enabling precise positioning and assembly without direct contact or interference with the balanced rotor assembly.
2Ease of operation
If rotor wheels are disassembled to allow nozzle ring assembly, then ease of operation is improved, but reliability worsens due to potential rotor unbalancing and mechanical damage
Solution Approach 1:
The invention performs preliminary assembly of the nozzle ring to the first casing half before final installation. This preliminary action allows the nozzle ring to be pre-positioned and secured in the correct orientation, ensuring that when the casings are assembled around the rotor, the nozzle ring is already in its final position without requiring rotor disassembly.
Solution Approach 2:
The temporary support serves as an intermediary that enables the nozzle ring to be assembled and positioned without direct manipulation of the rotor. This intermediary mechanism protects the rotor's balance by eliminating the need to disassemble or reposition rotor components during nozzle ring installation.
3Ease of operation
If split casing is used to facilitate nozzle assembly, then ease of operation is improved, but manufacturing precision worsens due to asymmetry and deformation
Solution Approach 1:
The invention intentionally designs the two casing halves with asymmetric features including different numbers of bolts, non-uniform spacing, and varied thicknesses. This controlled asymmetry allows each casing half to be optimized for its specific function and position, eliminating the symmetry-induced deformation problems while maintaining ease of assembly.
Solution Approach 2:
The invention applies different local qualities to different parts of the casing structure. The first and second casings have different configurations of bolts, spacing, and thicknesses tailored to their specific positions and functions. This local optimization ensures precise alignment and positioning of the nozzle ring while maintaining overall structural integrity.
Data Source
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AI summary
The invention relates to a method and apparatus for assembling nozzles 31 between buckets 41,42 of a turbine, particularly a gas turbine, in which a temporary fixing of the nozzles 31 to the buckets 41,42 during the assembly is provided.