Labyrinth Seal Drainage for Wet-Steam Turbine Vibration Control
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Solution Overview
Problem
Existing labyrinth seals in backpressure steam turbines malfunction when operating with wet steam, as liquid phase precipitation can fill grooves, block segment movement, and increase rotor-sealing system stiffness, leading to turbine vibration and critical speed changes.
Innovation Solution
The sealing system incorporates a drainage system with drain holes at the lowest points of the grooves, allowing liquid to be carried away by gravity, preventing blockage and ensuring smooth rotor movement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a labyrinth seal is used in a backpressure steam turbine, then steam leakage is reduced, but liquid accumulation in grooves blocks segment movement and increases rotor-sealing system stiffness
Solution Approach 1:
The drainage system extracts liquid from the grooves through drain holes located at the lowest points, preventing liquid accumulation that would otherwise block segment movement. This separation of liquid removal function from the sealing structure resolves the contradiction between maintaining seal integrity and ensuring segment mobility.
Solution Approach 2:
The drainage system acts as an intermediary mechanism between the grooves and the external environment, facilitating liquid removal without interfering with the primary sealing function. This mediator enables both good sealing performance and free segment movement by managing the harmful liquid phase.
2Productivity
If wet steam is processed, then turbine power generation is maintained, but liquid phase precipitation fills grooves and causes turbine vibration
Solution Approach 1:
The drainage system converts the harmful liquid accumulation into a beneficial drainage function. By providing drain holes at the lowest points of the grooves, the system utilizes gravity to naturally remove liquid, transforming the problem of liquid phase precipitation into a self-draining mechanism that prevents vibration while maintaining power generation from wet steam.
Solution Approach 2:
The drainage system enables self-service liquid removal through gravity-driven drainage via drain holes. The grooves automatically drain liquid without requiring external intervention, allowing the turbine to continuously process wet steam while preventing liquid accumulation that would cause vibration and performance degradation.
3Reliability
If groove depth is increased to improve sealing, then sealing effectiveness increases, but liquid accumulation risk increases
Solution Approach 1:
The groove structure is segmented with drain holes at the lowest points, creating separate drainage pathways within the grooves. This segmentation allows the grooves to maintain sufficient depth for effective sealing while providing dedicated drainage channels that prevent liquid accumulation, resolving the contradiction between sealing effectiveness and liquid accumulation risk.
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 drainage system effectively prevents liquid accumulation in the grooves, maintaining the integrity of the labyrinth seal and reducing the risk of turbine vibration and critical speed alterations.
Implementation Method 1
the drainage system with allows water (liquid) in the grooves, to dissipate. The drainage system is configured in that way, that liquid is carried away from the grooves by gravity
Data Source
Figure 1~2
AI summary
The invention concerns a sealing system for a steam turbine, consisting of at least one labyrinth seal, the labyrinth seal comprising at least one seal housing (1) with a couple of grooves (2) and a rotor with a couple of sealing tips, wherein the sealing tips engages in the grooves (2). The sealing house (1) contains a drainage system (3) with allows liquid in the grooves (2) to dissipate.