Valve Positioner Zero Bleed via Pilot Valve Segmentation
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Solution Overview
Problem
Conventional pneumatic valve positioners face challenges in achieving zero bleed in steady state conditions, requiring external power sources and additional components, which are costly and complex, especially in hazardous environments, and often result in leakage issues.
Innovation Solution
A valve positioner system with a low-power pilot valve controlled by an electronic circuit powered from the signaling and power connection, utilizing a plurality of pneumatic valves to enable fail-freeze and fail-safe operations with zero bleed in steady state conditions, eliminating the need for external power sources and reducing complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If normally closed on/off valves are used in valve positioner, then fail-safe operation is enabled, but the flow coefficient (Cv) is low and leakage occurs
Solution Approach 1:
The system divides the valve control into multiple stages: a low-power pilot valve (electro-pneumatic) controls larger pneumatic on/off valves. This segmentation allows the pilot valve to use minimal power for control signaling while the pneumatic valves handle the main fluid flow, achieving both reliability and reduced leakage.
Solution Approach 2:
The pilot valve acts as an intermediary between the electrical control circuit and the main pneumatic valves. It uses minimal electrical power to control the positioning of larger pneumatic valves, enabling fail-safe operation without requiring continuous high power input that would cause leakage in steady state.
2Loss of energy
If external power sources and additional components are used to achieve zero bleed, then steady state gas bleed prevention is enabled, but device complexity and cost increase
Solution Approach 1:
The system merges the control circuit and power supply into a single integrated unit that operates from the existing 4-20mA signaling loop. This eliminates the need for separate external power sources and additional components, achieving zero bleed while maintaining simplicity.
Solution Approach 2:
The electrical current signal loop serves multiple functions simultaneously: it provides both the control signal for valve positioning and the power supply for the control circuit. This multi-functionality eliminates the need for dedicated external power sources, reducing complexity while achieving zero steady state bleed.
3Loss of energy
If low power pilot valve is used, then zero bleed in steady state is achieved, but control power must be sourced from signaling loop
Solution Approach 1:
The signaling loop current serves dual purposes: it provides the control signal for valve positioning and simultaneously powers the low-power control circuit. This eliminates the need for separate power sourcing, achieving zero steady state bleed while maintaining adequate control power.
Solution Approach 2:
The control circuit is designed to draw its operating power from the same signaling loop that provides control signals. The system essentially powers itself, using the existing current loop to both control and energize the pilot valve, achieving zero external power requirements and zero steady state bleed.
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
The system achieves zero bleed in steady state conditions, ensuring safe and reliable operation in hazardous environments while reducing costs and complexity by using the electrical current signal loop for power, thereby enhancing the reliability and safety of pneumatic valve positioning.
Implementation Method 1
An electronic circuit converts a current signal received from a signaling and power connection to control a low power pilot valve
Implementation Method 2
The circuit controls a low power pilot valve that controls a plurality of pneumatic valves
Implementation Method 3
Compressed gas is forced into and out of the cylinder to move the connecting rod
Implementation Method 4
Pneumatic, hydraulic, electrical, or mechanical energy is converted by the actuator to linear or rotational motion
Data Source
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AI summary
A valve positioner system (12) with zero bleed at steady state is disclosed. The system has a pilot valve (30), the operation of which is controlled by an electronic circuit (34) powered from a signaling and power connection of a positioner device. A plurality of pneumatic valves (32) are activated and deactivated by the pilot valve to control a valve actuator (14). With varying configurations and arrangements of normally open or normally closed pilot valves and pneumatic valves, fail freeze and fail safe operations are contemplated. The activation and deactivation of the pilot valve is controlled by an electronic circuit that monitors a valve position signal.