Rotary Machine Casing Segmentation and Flange Design
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Solution Overview
Problem
Existing turbine casing designs face challenges in reducing size, preventing fluid leakage, and ensuring structural rigidity and maintenance accessibility, particularly in large turbines, due to increased size and complexity which affects performance and safety.
Innovation Solution
The casing is divided in the axial direction, with coupling flanges projecting minimally, and a central third flange supporting the blade ring, reducing overhang and enhancing thermal distribution, while a conical connection member enhances strength and prevents fluid leakage by acting as an end plate within the pressure vessel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the casing is divided into two on the horizontal surface with joining flanges on the entire periphery, then the rigidity of the entire apparatus is secured, but the casing itself is increased in size and the mass of the entire turbine is increased
Solution Approach 1:
The casing is divided into an upper casing and a lower casing along a horizontal division surface, allowing the structure to be assembled from segments while maintaining overall rigidity through strategic flange placement at critical locations rather than around the entire periphery
Solution Approach 2:
Joining flanges are provided only at specific locations (inlet end and/or outlet end) rather than on the entire periphery, concentrating structural reinforcement where needed while reducing overall casing size and weight
2Stability of the object's composition
If the casing is divided into two on the horizontal surface, then the rigidity is secured, but the range from which the working fluid leaks is increased due to the extended joining surface
Solution Approach 1:
The casing is segmented into upper and lower portions with joining flanges located at specific ends rather than continuously around the periphery, reducing the total length of joining surfaces where leaks could occur
Solution Approach 2:
A sealing structure is provided at the joining surface between the upper and lower casings, acting as an intermediary element that prevents working fluid leakage across the division surface
3Object-generated harmful factors
If the casing is hermetically closed as in the pot-like structure, then the leakage range is reduced, but such structure can be employed only to a relatively small turbine and must be replaced with flange structure in large turbines which increases the axial length
Solution Approach 1:
The casing is divided into upper and lower casings with joining flanges positioned at the inlet and/or outlet ends, allowing the structure to accommodate larger turbine sizes while minimizing axial length extension compared to traditional horizontal flange configurations
Solution Approach 2:
The division surface is oriented horizontally rather than axially, changing the dimensional orientation of the joint to reduce axial length projection while maintaining sealing effectiveness
4Device complexity
If the blade ring is supported in a cantilever manner at the end opening, then the structure is simplified, but the overhang is made longer and the center is not sufficiently held with increased thermal extension influence
Solution Approach 1:
The blade ring support structure is segmented with the blade ring positioned between the upper and lower casings, allowing for better center alignment and reduced thermal extension influence compared to cantilever support at a single end
Solution Approach 2:
The blade ring is positioned at a location where thermal extension effects are balanced between the upper and lower casings, creating a more stable thermal environment that maintains center precision
Data Source
AI summary
To reduce the size of a rotary machine and to provide a rotary machine in which it is possible to achieve an improvement in reliability and performance of the rotary machine. A first casing (1) and a second casing (2) formed by dividing a substantially cylindrical casing (101), enclosing in the interior thereof a rotor shaft (4) in which rotor blades (11) are embedded, into two at substantially a central portion relative to an axial direction of the rotor shaft (4) are provided; a first coupling flange (1A) and a second coupling flange (2A) are provided at openings in the first casing (1) and the second casing (2), respectively; a third coupling flange (3A) is provided, which is enclosed by the casing (101), which is positioned at substantially a central portion of the length in the axial direction in a substantially cylindrical blade ring (3) holding stator blades (10) and enclosing the rotor shaft (4), and which holds the blade ring (3); the first casing (1), the second casing (2), and the blade ring (3) being assembled by sandwiching the third coupling flange (3A) between the first coupling flange (1A) and the second coupling flange (2A).