Steam Turbine Bellows Sealing Mechanism for Resonance Control
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Solution Overview
Problem
Conventional sealing mechanisms for steam turbines face challenges in easily determining and adjusting the natural frequencies of bellows-joints, leading to difficulties in preventing vibration resonance between the sealing mechanism and the rotor shaft system, requiring surplus time and labor for manufacturing and testing.
Innovation Solution
The sealing mechanism features outer and inner bellows-joints arranged to avoid contact, allowing for easy computation and adjustment of natural frequencies without special vibration adjusting means, with the inner bellows-joint nested inside the outer bellows-joint, eliminating the need for precise contact considerations and reducing manufacturing complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a double layer bellows-joint structure is used to seal the space around the rotor shaft, then steam leakage prevention is improved, but determining and adjusting natural frequencies becomes difficult and time-consuming
Solution Approach 1:
The patent applies nesting by placing the inner bellows-joint inside the outer bellows-joint, with both joints concentrically arranged around the rotor shaft. This nested configuration allows the inner and outer joints to work together for sealing while enabling independent calculation of their natural frequencies, eliminating the need for complex interaction analysis and significantly reducing the time required for frequency determination and adjustment.
2Device complexity
If the inner and outer bellows-joints are arranged to avoid contact, then computation of natural frequencies is simplified, but the structural complexity increases
Solution Approach 1:
The patent applies local quality by providing support members at specific locations along the bellows-joints. These support members maintain the concentric arrangement and prevent contact between the inner and outer joints without requiring high precision throughout the entire structure. The support members are strategically positioned to provide stability where needed while allowing the simplified non-contact configuration.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach simplifies the handling of natural frequencies, reduces the need for vibration tests, and enhances the durability of the sealing mechanism, ensuring effective steam sealing and resonance avoidance without increasing labor or time expenditure.
Implementation Method 1
the bellows joint is able to absorb the relative displacement between the outer casing and the gland, the relative displacement being caused by thermal expansion or working pressure
Implementation Method 2
the sealing mechanism hermetically sealing an area around the rotor shaft
Data Source
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AI summary
Providing a sealing mechanism provided with bellows-joints, the sealing mechanism being manufactured without surplus time and labor; thereby, the natural frequencies regarding the sealing mechanism surrounding a to-be-sealed shaft body are easily handled. Around a rotor shaft 26 of a steam turbine 10, between an outer turbine casing 12 and a gland 32, a sealing mechanism 40A is provided; the sealing mechanism is provided with an outer bellows-joint 46 and an inner bellows-joint 48, both the joints being arranged without mutual contact; the left and right ends of the outer bellows-joint 46 are gas-tightly connected to the outermost end periphery of the end flange 42 and the end flange 44, respectively; the left and right ends of the inner bellows-joint 48 are gas-tightly connected to the innermost end periphery of the end flange 42 and the end flange 44, respectively. Positioning both the bellows-joints can be easily performed.