Steam Turbine Bling Nozzle Carrier Interface Design
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Solution Overview
Problem
Current steam turbine nozzle construction methods, such as band/ring and fillet weld methods, suffer from weld distortion, stress issues, and complex analysis due to mechanical interfaces, leading to inefficiencies and difficulties in assembly and disassembly, especially after corrosion sets in.
Innovation Solution
A bling-type nozzle design with a modified interface between the outer ring and carrier, featuring strategically placed circumferential lands to allow radial sliding while restricting axial movement, reducing downstream deflection and improving sealing and disassembly by eliminating crush pins and using low-heat welds for assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If weld methods (band/ring or fillet weld) are used to construct nozzle diaphragms, then assembly is achieved, but weld distortion occurs in flow path and steam path sidewalls causing efficiency losses
Solution Approach 1:
The patent removes the weld joints from the nozzle construction by using a monolithic bling design where the nozzle is a single piece of metal formed without welding. This extraction of the harmful welding process eliminates weld distortion in the flow path and steam path sidewalls while maintaining structural integrity through continuous material.
Solution Approach 2:
The patent merges the nozzle body and carrier into a single integrated bling component that is formed as one monolithic structure. This combining eliminates the need for separate nozzle pieces and weld joints, resulting in a unified structure that prevents distortion while maintaining manufacturing feasibility through forming processes.
2Manufacturing precision
If crush pins are used to maintain tight tolerance between diaphragm and casing, then axial positioning is achieved, but disassembly becomes difficult after corrosion occurs
Solution Approach 1:
The patent segments the axial positioning function from the structural connection by using a tight tolerance interface between the bling outer ring and carrier groove that provides positioning without creating a permanent bond. This separation allows the bling to be precisely positioned axially while remaining removable after service, as the interface relies on dimensional precision rather than mechanical fasteners that corrode.
Solution Approach 2:
The patent introduces a precision-machined interface between the bling outer ring and carrier groove as an intermediary mechanism. This interface acts as a mediator that provides axial positioning and loading functions without creating a permanent or corrosion-prone connection, allowing easy removal after service while maintaining precise positioning during operation.
3Reliability
If tight interface between bling and carrier is used for sealing, then sealing is improved, but downstream deflection increases
Solution Approach 1:
The patent applies local quality by creating a tight interface only in specific locations where sealing is required, while maintaining a looser fit in other areas to allow thermal expansion and reduce downstream deflection. The groove and outer ring interface provides localized sealing contact without constraining the entire bling structure, allowing it to deflect thermally without compromising the seal at critical locations.
Data Source
AI summary
A bling nozzle/carrier interface design for a steam turbine is provided wherein there is limited contact between the carrier (casing, shell) to allow for ease of assembly. There is also limited contact in strategic locations to both reduce the roll, or downstream deflection, of the inner portion and to improve disassembly due to limited contact in areas where corrosion can occur.