Steam Turbine Valve Actuator Bypass Line for Low-Loss Positioning
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Solution Overview
Problem
Existing actuators for steam turbine control valves face inefficiencies due to throttling losses, high demands on constant supply pressure, and thermally unfavorable operating conditions for the working medium pump and motor, particularly in maintaining holding pressure and dissipating heat at low volume flows.
Innovation Solution
The actuator design includes a working cylinder with a short-circuit line connecting the first and second pressure chambers, allowing continuous working medium flow from the pressure side to the suction side, even when the piston is stationary, and a motor-driven working medium pump that can operate without throttling valves, enabling efficient heat dissipation and energy recovery by reversing direction or alternating pressure and suction connections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If throttling directional valves are used to control working medium flow, then the valve position can be regulated, but throttling losses increase and efficiency is limited
Solution Approach 1:
The invention extracts and removes the throttling directional valves from the system. Instead of using valves to control working medium flow to the piston, the patent directly connects the pump to the piston chambers, eliminating the throttling elements that cause energy losses while maintaining position control capability through direct pump control.
Solution Approach 2:
The invention replaces the mechanical valve-based flow control system with a direct pump-to-piston connection system. This substitution eliminates the need for throttling directional valves and their associated throttling losses, achieving more efficient working medium delivery while maintaining position regulation capability.
2Measurement precision
If constant supply pressure is maintained for precise piston positioning, then positioning precision is improved, but demands on the working medium pump and motor increase
Solution Approach 1:
The invention implements dynamic control where the pump's pressure and flow are continuously adapted to the actual positioning requirements. Instead of maintaining constant high supply pressure, the system adjusts pump output dynamically based on the piston's position and velocity needs, reducing power demands while preserving positioning precision through active control.
Solution Approach 2:
The invention changes the operating parameters of the working medium pump and motor to match actual load requirements. By varying pressure and flow parameters dynamically rather than maintaining constant high values, the system reduces power consumption while achieving the necessary positioning precision through controlled parameter adjustment.
3Reliability
If the working medium pump operates at low volume flow to maintain holding pressure, then position holding is achieved, but thermally unfavorable conditions cause overheating
Solution Approach 1:
The invention implements periodic or cyclic operation where the pump alternates between delivering working medium to maintain position and operating at higher flow rates for cooling. This periodic action allows the system to maintain position holding capability while periodically reducing temperature through higher flow operation, preventing thermal overload.
Solution Approach 2:
The invention ensures continuous useful action by maintaining the pump in operation rather than shutting it off for position holding. The pump continues to circulate working medium at adjusted flow rates, providing both position maintenance through pressure control and continuous cooling through fluid circulation, eliminating the thermal overload problem associated with low-flow holding operations.
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 reduces throttling losses, maintains efficient operation across speed ranges, avoids thermally unfavorable conditions, and allows for partial energy recovery, enhancing the actuator's dynamic adjustment and positioning precision while minimizing production costs.
Implementation Method 1
a working medium pump (13), in particular a hydraulic pump, which can be driven by a motor (12), in particular an electric motor, and has a suction side (14) and a pressure side (15)
Implementation Method 2
to push the piston with the piston rod (3) in or out against the force of a spring (4), in particular a compression spring
Data Source
Figure 1
AI summary
The invention relates to an actuating drive for a control valve, in particular a steam turbine control valve, having a working cylinder which has a piston and a piston rod connected thereto, and which forms an actuator for the control valve, wherein the piston bounds a first pressure space with a first pressure connection and a second pressure space with a second pressure connection in order to displace the piston, with the piston rod, counter to the force of a spring assigned to the working cylinder by applying pressure to the first pressure space by introducing a pressurized working medium via the first pressure connection; with an external working medium circuit to which the working cylinder is connected with its first and second pressure connections in order to introduce and evacuate working medium into/from the first and second pressure spaces; wherein the external working medium circuit has a working medium pump which is driven by a motor, has a suction side and a pressure side and is connected, so as to convey working fluid, at the pressure side, via a pressure line, to the first pressure connection, and at the suction side, via a tank line, to the second pressure connection. The control valve according to the invention is characterized in that the first pressure space is permanently connected, so as to convey working fluid, to the second pressure space via a bypass line.