Steam Turbine Casing Position Adjustment Using Radial Actuators
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Solution Overview
Problem
The existing steam turbine casing position adjusting apparatuses face challenges in controlling the rotation of the turbine casing to prevent yawing, require high-resolution and large-stroke actuators, and increase the size and cost of the turbine, while also failing to accurately measure thermal elongation differences between the turbine casing and rotor, leading to reduced efficiency and potential damage from thermal expansion.
Innovation Solution
The proposed solution involves positioning the actuator away from the central axis of the turbine casing, using a compact actuator outside the outer casing to avoid thermal damage, and employing sensors to accurately measure thermal elongation differences, allowing for precise control of the turbine casing position and reduction of clearance between the casing and rotor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the actuator is positioned closer to the center line of the turbine casing, then the turbine casing can be moved axially, but the turbine casing rotates (yaws) about its center of gravity, requiring extremely high resolution actuators
Solution Approach 1:
The patent positions the actuator at a location away from the central axis of the turbine casing, utilizing the radial dimension to create a lever arm. This dimensional change transforms the control mechanism, allowing axial movement without inducing rotation, thereby eliminating the need for extremely high resolution actuators.
2Reliability
If the actuator is positioned where it is affected by thermal elongation of the turbine casing, then the rod must recede to absorb thermal expansion, requiring large-stroke actuators
Solution Approach 1:
The patent extracts the actuator from the thermal environment by positioning it outside the outer casing. This separation removes the actuator from the thermal expansion zone, eliminating the need for large-stroke actuators to compensate for thermal elongation of the casing.
3Manufacturing precision
If the actuator is disposed on the end surface of the turbine casing, then the axial movement is achieved, but the size of the steam turbine increases in the axial direction
Solution Approach 1:
The patent nests the actuator within the radial space of the turbine casing by positioning it on the outer surface of the outer casing. This nested arrangement utilizes the existing radial dimensions rather than extending the axial length, thereby maintaining a compact overall turbine size while achieving the required casing position adjustment.
4Device complexity
If conventional casing position adjusting apparatus is used, then the structure is simple, but it cannot reduce thermal elongation difference between the rotor and inner casing
Solution Approach 1:
The patent introduces an arm as an intermediary mechanical element that connects the actuator to the inner casing. This arm transmits the axial movement force from the actuator to the inner casing, enabling thermal elongation difference reduction while maintaining a relatively simple overall structure.
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 enables fine control of turbine casing rotation, reduces the size and cost of the steam turbine, improves efficiency by minimizing clearance between the casing and rotor, and extends the lifespan of components by avoiding thermal damage.
Implementation Method 1
reducing a thermal elongation difference due to the relative thermal expansion of the inner casing 21 and the rotor 23
Data Source
Figure 1~2
Figure 3~5
Figure 6~7
AI summary
A steam turbine casing position adjusting apparatus capable of employing a compact low-resolution actuator is provided. A steam turbine casing position adjusting apparatus 40 includes turbine casings 21 and 37, a rotor 23, and actuators 14 and 15 that move the turbine casings 21 and 37 in the axial direction. The actuators 14 and 15 are disposed radially outside outer peripheries forming the turbine casings 21 and 37.