Steam Turbine Casing Segmentation for Bellows Machining
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Solution Overview
Problem
Conventional steam turbine casing structures face challenges in machining and assembling large-sized outer casings, particularly with the bellows fitting unit, due to axial deviation and height limitations, making it difficult to perform machining and transport in existing facilities.
Innovation Solution
The outer casing is divided into upper and lower casings on a horizontal plane, with the upper casing further divided into a middle block and an upper block with a top panel, allowing for machining of the bellows fitting unit in existing facilities without full assembly, and enabling easier disassembly and transport by reducing the height requirement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the outer casing is made large to increase power generation efficiency, then the power generation efficiency is improved, but the machining of the bellows fitting unit cannot be performed in existing facilities
Solution Approach 1:
The outer casing is divided into an upper casing and a lower casing along a horizontal plane. The upper casing is further divided into a middle block and an upper block. This segmentation allows the bellows fitting unit to be machined in the middle block separately before assembly, enabling machining in existing facilities without requiring the entire large casing to be present.
2Ease of operation
If the outer casing is assembled in a vertically integrated manner to improve workability, then the workability is improved, but the facility height needs to be increased
Solution Approach 1:
The upper casing is divided into a middle block and an upper block that can be assembled horizontally on the ground in existing facilities without requiring increased facility height. After assembly, the combined unit is then installed vertically in the steam turbine, separating the assembly process from the installation process.
3Device complexity
If the upper casing is not divided to maintain structural simplicity, then the structural simplicity is maintained, but the bellows fitting unit cannot be machined accurately in existing facilities
Solution Approach 1:
The upper casing is segmented into a middle block containing the bellows fitting unit and an upper block. This allows the middle block to be machined with high precision in existing facilities before assembly. The segmentation is minimal and only where necessary for machining access, maintaining overall structural simplicity.
Data Source
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AI summary
In a steam turbine according to a first embodiment, an outer casing 11 is divided into an upper casing 31 and a lower casing (a lower block) 32 on a horizontal plane through which a rotor passes, and the upper casing 31 is divided into a middle block 33 having a through hole 20 and an upper block 34 having a top panel 31a, that is, into a portion including at least a part of the through hole 20 through which the rotor penetrates and other parts. With this configuration, machining of a bellows fitting unit provided in an end-plate cone portion 21A can be performed in existing facilities such as a factory, in a state that the lower block 32 and the middle block 33 are assembled without assembling the upper block 34.