Steam Turbine Stationary Vane Heating to Reduce Wet-Steam Erosion
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Solution Overview
Problem
The existing steam turbine designs suffer from efficiency degradation and erosion issues due to high wetness fractions in the final stages, where steam interference and leakage lead to significant losses and surface damage on stationary vanes.
Innovation Solution
A steam turbine configuration featuring a rotor with a casing and stationary vanes, where the first stationary vane has a through hole allowing steam to flow from upstream to a cavity, reducing interference and leakage losses, and utilizing high-temperature steam to heat the vane surfaces, thereby suppressing liquid drop formation and erosion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If high-temperature steam is discharged toward the tip ends of downstream rotor blades to heat stationary vanes, then liquid drop generation on vane surfaces is suppressed, but interference between main flow and discharged steam causes efficiency degradation
Solution Approach 1:
The invention extracts the harmful discharged steam away from the main flow path by introducing it into a cavity formed by the rotor blade and casing. This separates the heating function from the main steam flow, eliminating interference losses while maintaining the anti-liquid drop effect on stationary vanes.
Solution Approach 2:
The cavity acts as an intermediary space that receives and contains the discharged steam, preventing its direct interference with the main flow. The cavity mediates between the steam discharge function and the main flow path, allowing both to coexist without negative interaction.
2Temperature
If steam is extracted from upstream space to flow through the through hole, then the first stationary vane is heated effectively, but leakage steam flowing into the cavity causes loss
Solution Approach 1:
The invention converts the harmful leakage steam into a beneficial heating medium by directing it through the steam passage and through hole to heat the first stationary vane. What would otherwise be a loss becomes a useful thermal source, simultaneously achieving vane heating and reducing energy waste.
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 configuration effectively reduces erosion and efficiency degradation by minimizing steam interference and leakage, while utilizing high-temperature steam to maintain vane surface dryness and reduce operational losses.
Implementation Method 1
the temperature of steam extracted from the space upstream of the first stationary vane is higher than the temperature of the first stationary vane, and thus it is possible to heat the first stationary vane easily by allowing the steam to flow through the through hole
Implementation Method 2
as steam having passed through the through hole of the first stationary vane is discharged into the cavity from the inner race of the first stationary vane, compared to the configuration of Patent Document 1, it is possible to reduce loss due to interference between main flow flowing through the casing
Data Source
AI summary
A steam turbine includes a rotor; a casing which houses the rotor; a plurality of rotor blades disposed around the rotor; and a plurality of stationary vanes supported on the casing. The stationary vane includes a vane body portion and an inner race positioned on an inner side of the vane body portion in a radial direction of the rotor. The stationary vanes include a first stationary vane having a through hole formed through the vane body portion. The rotor has a cavity having a concave shape and being formed such that at least a part of the inner race of the first stationary vane is housed in the cavity. The steam turbine includes a steam passage to discharge steam extracted from a space upstream of the first stationary vane in the casing to the cavity from the inner race through the through hole of the first stationary vane.