Steam Turbine On-Off Valve Box for Uniform Thermal Deformation
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Solution Overview
Problem
In steam turbines, the on-off valve's design leads to steam stagnation, resulting in uneven heat transfer and thermal deformation of the valve box, which can cause the valve body to malfunction due to perpendicular flow paths and a support shaft penetrating the valve box, leading to inadequate heat transfer and increased temperature gradients.
Innovation Solution
The on-off valve design includes a valve box with a thinner downstream wall thickness opposite to the outlet flow path, a metal member for heat storage, and an uneven inner surface to enhance heat transfer, along with a gap between the drive unit and valve box to promote uniform thermal deformation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the support shaft penetrates the valve box at the position where the flow direction changes, then the valve body can be supported and operated, but the steam flow stagnates at this position causing uneven heat transfer and thermal deformation
Solution Approach 1:
The valve box is designed with non-uniform wall thickness, where the wall thickness varies in different regions. Specifically, the wall thickness is greater at positions prone to steam stagnation and thermal deformation, and thinner at other positions. This local variation in structural properties compensates for the uneven heat distribution, maintaining overall dimensional stability and preventing valve body operation issues.
2Ease of manufacture
If the wall thickness of the valve box is uniform, then the manufacturing is simplified, but the thermal deformation becomes uneven due to steam stagnation at the flow direction change position
Solution Approach 1:
The valve box employs non-uniform wall thickness distribution tailored to the thermal conditions at different locations. The wall thickness is increased at regions experiencing steam stagnation and higher thermal gradients, while being reduced in areas with better heat transfer. This localized structural adaptation ensures uniform thermal deformation characteristics without significantly complicating the manufacturing process.
3Volume of moving object
If the outlet flow path extends perpendicular to the communication hole, then the compact design is achieved, but the steam flow stagnation occurs around the valve support portion
Solution Approach 1:
The valve box maintains a compact design with the outlet flow path extending perpendicular to the communication hole, while compensating for the resulting steam stagnation through non-uniform wall thickness. The wall thickness is strategically increased at the stagnation-prone regions around the valve support portion, ensuring adequate heat transfer and preventing thermal deformation that would compromise reliability.
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 ensures smooth operation of the valve body by reducing temperature gradients and thermal deformation, preventing valve malfunctions and ensuring consistent heat dissipation.
Implementation Method 1
a minimum wall thickness of the valve box on a side, which is positioned on a downstream side from the communication hole and is opposite to a side to which the outlet flow path extends across the valve support portion, is smaller than a minimum wall thickness of the valve box on an upstream side from the communication hole
Implementation Method 2
a metal member which is fixed to an outer surface of the valve box on a downstream side from the communication hole and on a side to which the outlet flow path extends across the valve support portion
Implementation Method 3
an uneven portion is provided on an inner surface around the valve support portion
Implementation Method 4
a gap is provided between the drive unit and the valve box on a side opposite to a side to which the outlet flow path extends across the valve support portion
Implementation Method 5
a position of a portion which is heated by steam and has a high temperature and a position of a portion to which heat is not sufficiently transferred by the steam and which has a low temperature occur. In addition, at the position having a relatively low temperature, a temperature gradient of the wall surface of the valve box increases, and thus, thermal deformation of the valve box becomes uneven
Data Source
AI summary
An on-off valve of the present invention includes a valve box which includes an inlet flow path of steam and an outlet flow path which communicates with the inlet flow path through a communication bole, a stop valve body which opens or closes the communication hole, and a stop valve support portion, in which the outlet flow path extends in a direction intersecting the opening direction of the communication hole toward a downstream side in a flow direction of the steam, and a minimum wall thickness of the valve box is smaller than a minimum wall thickness of the valve box.