Steam Valve Actuation With Dynamic Fail-Safe Hydraulic Closure
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Solution Overview
Problem
The existing steam valve driving apparatuses face challenges in rapidly closing the steam valve due to the constant biasing force applied by the closing spring, which prolongs the overspeed characteristic of the steam turbine and increases the cylinder volume, leading to inefficiencies in emergency shutdowns.
Innovation Solution
A steam valve driving apparatus with a double-acting cylinder configuration, utilizing a control valve, dump valves, an accumulator, and a trip solenoid valve to manage hydraulic oil flow, allowing the fail-safe function to be applied only during emergency shutdowns, thereby preventing the biasing force from being applied as a load when the steam valve is open, and enabling rapid discharge of control oil for efficient closure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a closing spring is constantly applied to provide fail-safe function, then the steam valve can be safely closed during emergencies, but the biasing force is constantly applied as a load to the piston which increases cylinder volume and prolongs oil discharge time
Solution Approach 1:
The patent applies dynamics by making the closing spring force active only when needed. The spring is positioned to apply biasing force to the piston only when the valve is in the closed position or during emergency closure, rather than constantly. This is achieved through the specific arrangement where the spring acts on the piston rod or piston only in the closed state, allowing rapid oil discharge during emergencies while maintaining fail-safe capability.
Solution Approach 2:
The patent implements periodic action by applying the closing spring force intermittently rather than continuously. The spring force is applied periodically - active during closed state and emergency closure, but not during normal open state operation. This periodic application reduces the time the load is present on the piston, thereby reducing oil discharge time while maintaining the fail-safe function when needed.
2Reliability
If a closing spring is constantly applied to provide fail-safe function, then the steam valve can be safely closed during emergencies, but the constant biasing force increases the cylinder volume
Solution Approach 1:
The patent reduces cylinder volume by making the spring force dynamic rather than static. The cylinder is designed to accommodate the spring force only when the valve is closed or during emergency closure, not during normal operation. This is achieved by positioning the spring to act on the piston rod or piston only in the closed state, allowing for a smaller cylinder volume that doesn't need to accommodate constant spring pressure.
3Reliability
If the cylinder volume is increased to accommodate the biasing force, then the fail-safe function can be maintained, but the time for discharging control oil is prolonged
Solution Approach 1:
The patent improves emergency shutdown speed by making the spring force dynamic. The spring applies force only when the valve is closed or during emergency closure, not during normal open state. This dynamic application reduces the volume of control oil that needs to be discharged during emergencies, thereby speeding up the shutdown process while maintaining fail-safe capability.
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 allows for rapid and efficient closure of the steam valve during emergencies while preventing the fail-safe force from being applied as a load when the valve is open, reducing cylinder volume and improving the overspeed characteristic of the steam turbine.
Implementation Method 1
an opening direction piston chamber to which hydraulic oil that presses the piston in the opening direction of the steam valve is supplied
Implementation Method 2
a closing direction piston chamber to which hydraulic oil for pressing the piston in the closing direction of the steam valve is supplied
Data Source
AI summary
In a steam valve driving apparatus according to an embodiment, a control valve permits or blocks a flow of hydraulic oil from a supply port to an opening direction piston chamber. A dump valve blocks or permits the flow of the hydraulic oil from the opening direction piston chamber to a discharge port. A blocking valve permits or blocks a flow of the hydraulic oil from an accumulator to a closing direction piston chamber. The control valve permits the flow of control oil from the closing direction piston chamber to the discharge port in a state where the flow of hydraulic oil from the supply port to the opening direction piston chamber is permitted.