Flexurally Deformable Partitioning Plate for Steam Turbine Sealing
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Solution Overview
Problem
In steam turbines, high-pressure steam can flow into gaps between the outer and inner cases, causing temperature variations that weaken the fastening force of bolts due to rapid temperature changes, and existing partitioning plates fail to maintain an air-tight seal due to thermal expansion and temperature differences.
Innovation Solution
A fluid seal structure with a flexurally deformable partitioning plate that contacts a protruding portion in response to internal fluid pressure differences, creating an annular seal between space sections, and an annular seal member with a higher linear expansion coefficient to enhance sealing properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a partitioning plate is disposed to provide an air-tight seal between space sections during assembly, then the seal should prevent steam flow, but gaps are produced during operation due to thermal expansion and temperature differences
Solution Approach 1:
The partitioning plate is designed to be flexurally deformable rather than rigid, allowing it to dynamically adjust its position in response to temperature changes and steam pressure during operation. This dynamic flexibility enables the plate to maintain contact with the protruding portion and preserve the air-tight seal despite thermal expansion and contraction, preventing gap formation that would occur with a rigid plate.
Solution Approach 2:
The invention changes the physical state and mechanical properties of the partitioning plate by selecting a material with appropriate flexibility characteristics. The plate's flexural deformability allows it to adapt to varying temperature and pressure conditions, maintaining sealing effectiveness across different operational parameters without requiring rigid structural integrity.
2Temperature
If low-temperature steam flows through the space between outer case and inner case, then the outer case is cooled along the axial direction, but rapid temperature reduction weakens the fastening force of bolts
Solution Approach 1:
The partitioning plate divides the space between the outer case and inner case into separate upstream and downstream space sections. This segmentation prevents low-temperature steam from the downstream section from flowing into the upstream section, thereby preventing rapid temperature reduction in the upstream area and maintaining bolt fastening force by avoiding thermal contraction.
3Ease of manufacture
If the partitioning plate is made rigid to maintain seal, then assembly is simple, but gaps form during operation due to thermal expansion and temperature differences
Solution Approach 1:
The partitioning plate transitions from a rigid structure to a flexurally deformable one, enabling it to dynamically adapt to thermal and pressure variations during operation. This dynamic property ensures the plate maintains contact with the protruding portion to preserve the air-tight seal, overcoming the limitation of rigid plates that cannot accommodate thermal expansion and contraction.
4Temperature
If high-pressure steam flows into the space from the opposite side to exhaust outlet, then the temperature of outer case increases along the axial direction, but temperature variation creates thermal stress
Solution Approach 1:
The partitioning plate segments the space into upstream and downstream sections, controlling steam flow paths. By preventing low-temperature steam from entering the upstream section, the invention reduces temperature gradients and associated thermal stress in critical areas, protecting the outer case and bolt assembly from thermal damage.
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
The solution provides an air-tight seal between space sections, reducing temperature gradients and preventing bolt loosening by ensuring the partitioning plate contacts the protruding portion securely, maintaining a stable fastening force and preventing steam flow between sections.
Implementation Method 1
the partitioning plate is flexurally deformable in the axial direction of the turbine rotor by an internal fluid pressure difference between the first space section and the second space section
Implementation Method 2
an annular seal member with a higher linear expansion coefficient to enhance sealing properties
Data Source
AI summary
A fluid seal structure of a heat engine including a steam turbine includes an inner case which houses a turbine rotor rotatably inside, an outer case which houses the inner case and forms a space through which a fluid can flow between the outer case and an exterior surface of the inner case, a protruding portion protruding into the space from one of the exterior surface of the inner case or an interior surface of the outer case, and a partitioning plate extending into the space from the other one of the exterior surface or the interior surface and being formed annularly in a circumferential direction of the surface. The partitioning plate partitions the space into first and second space sections, and is flexurally deformable in the axial direction of the turbine rotor by an internal fluid pressure difference between the first and second space sections.