Steam Turbine Vane Heating Passages for Moisture and Erosion Control
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Solution Overview
Problem
Existing steam turbines face complexity and efficiency losses due to the need for a supply line and control valve to heat final-stage stationary vanes, leading to moisture loss and erosion in wet region conditions, especially when leak steam is used, which increases steam leakage and reduces turbine efficiency.
Innovation Solution
A steam turbine design featuring a first-stage stationary vane with a radial through hole that introduces steam from a cavity, maintaining a temperature higher than the main steam to prevent condensation without evaporation, and a second-stage through hole configuration that reduces steam flow velocity and leakages, thereby minimizing moisture loss and erosion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If leak steam is introduced into final-stage stationary vanes to evaporate liquid drops, then moisture loss and erosion are prevented, but device complexity increases due to supply line and control valve
Solution Approach 1:
The invention extracts the steam heating function from the main steam flow path by utilizing leak steam that would otherwise be wasted. The leak steam is directed through a simplified passage system directly to the stationary vane surfaces, eliminating the need for complex supply lines and control valves while maintaining the moisture removal function
Solution Approach 2:
The stationary vanes are designed with built-in heating passages that allow them to self-heat using the available leak steam. The vanes' own structure serves as the heating system, eliminating external control mechanisms and reducing device complexity while maintaining reliability
2Reliability
If high-temperature steam before high-pressure stage is introduced to evaporate liquid drops, then moisture loss and erosion are prevented, but energy consumption increases due to great heat requirement
Solution Approach 1:
The invention changes the temperature parameter of the heating steam from high-temperature pre-high-pressure steam to moderate-temperature leak steam. By adjusting the heating mechanism to use lower temperature steam with sufficient heat transfer area, the energy consumption is reduced while still achieving effective liquid drop evaporation
Solution Approach 2:
The invention converts the harmful effect of leak steam (which represents energy loss) into a beneficial heating source. The leak steam that would otherwise be wasted is utilized to heat the stationary vanes and evaporate liquid drops, turning an energy loss into a functional benefit without requiring additional energy input
3Reliability
If leak steam is extracted from shaft-seal packing to heat stationary vanes, then moisture loss and erosion are prevented, but steam turbine efficiency decreases due to increased steam leakage
Solution Approach 1:
The invention converts the harmful energy loss from steam leakage into a beneficial heating source. The leak steam extracted from the shaft-seal packing is directed to heat the stationary vanes and evaporate liquid drops, transforming what would be wasted energy into a functional benefit that prevents moisture loss and erosion
Solution Approach 2:
The invention recovers the energy value of leak steam that would otherwise be discarded. By capturing and utilizing the leak steam for heating purposes, the system recovers energy that would be lost, thereby maintaining or improving overall turbine efficiency rather than reducing it
4Reliability
If hollow-sectional stationary vanes with slits are used to remove liquid drops, then moisture loss and erosion are reduced, but device complexity increases
Solution Approach 1:
The invention merges the liquid drop removal function with the steam heating function into a single integrated system. The heating passages are built into the stationary vane structure itself, combining the thermal field and fluid removal functions, which simplifies the overall device structure compared to separate hollow-sectional vanes with slits
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 design simplifies the structure, reduces moisture loss and erosion by controlling liquid drop formation and condensation, and enhances overall turbine efficiency by minimizing steam leakage and maintaining a stable steam flow.
Implementation Method 1
steam introduced from the first cavity via an inlet opening of the first-stage through hole flows through the first-stage through hole
Implementation Method 2
liquid drops that condensate on a part of the surfaces of the stationary vanes where the temperature is lower than the main steam
Data Source
AI summary
A steam turbine according to an embodiment of the present invention includes: a rotor configured to rotate about an axis; a casing which houses the rotor; and a first stage including a first-stage stationary vane fixed to an inner wall portion of the casing and a first-stage rotor blade fixed to the rotor at downstream of the first-stage stationary vane. The rotor includes a first cavity having a concave shape and being formed on a portion facing the first-stage stationary vane, the first cavity being in communication with an inner space defined between the inner wall portion and the rotor at upstream of the first-stage stationary vane. The first-stage stationary vane includes a first-stage through hole which is in communication with the first cavity and which is formed through the first-stage stationary vane in a radial direction.