Control Valve Grounding Resistance Monitoring for Static Charge Safety
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Solution Overview
Problem
Current control valves in process plants do not effectively monitor the ohmic resistance between the valve rod and the housing, leading to a risk of static charging and potential explosions, as existing solutions like electrostatic draining devices are not designed for changes in contact resistance over time.
Innovation Solution
A control valve with a measuring device that continuously monitors the ohmic transition resistance between the valve rod and the grounded housing using a measuring line that connects the valve rod to the valve housing, allowing for immediate detection of any impending explosion hazard, and includes a transformer-based measurement circuit and evaluation device for processing and displaying resistance values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a measuring device is integrated into the control valve for continuous monitoring, then the safety and reliability are improved, but the device complexity increases
Solution Approach 1:
The measuring device is integrated into the control valve assembly, merging the measurement function with the existing valve structure. The measuring line is routed through existing components such as the actuating drive and positioner, combining multiple functions into a unified system rather than adding separate standalone monitoring equipment.
Solution Approach 2:
Existing components of the control valve system are made multi-functional. The actuating drive and positioner serve both their original control functions and additionally host the measuring device and provide conduction paths for resistance monitoring. This allows one system to perform multiple functions without proportionally increasing complexity.
2Ease of manufacture
If the measuring line is routed through existing components, then the ease of manufacture is improved, but the measurement precision may be affected by additional contact points
Solution Approach 1:
The measuring line uses existing conductive components as intermediaries to reach the valve rod. Rather than creating direct contact points that would require precise alignment and maintenance, the measurement signal travels through the actuating drive and positioner components that already provide stable electrical connections, reducing measurement errors from contact instability.
Solution Approach 2:
The measuring line is divided into multiple segments routed through different existing components (actuating drive, positioner, lever arm, shaft). Each segment uses existing contact points and conduction paths, distributing the measurement function across multiple reliable interfaces rather than relying on a single critical contact point.
3Reliability
If constant monitoring is implemented, then the reliability is improved, but the use of energy increases
Solution Approach 1:
The continuous monitoring system uses electrical measurement through the existing actuating drive and positioner components rather than mechanical sensing methods. This electrical approach allows for continuous monitoring with minimal energy consumption, as it utilizes the existing electrical infrastructure of the control valve system without requiring additional power-intensive mechanical sensors or actuators.
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
Enables constant monitoring of the transition resistance, ensuring safe grounding and preventing static charging, thereby reducing the risk of explosions by providing real-time monitoring and alarm capabilities.
Implementation Method 1
a measuring device for the ohmic measurement of the transition resistance of the contact device is provided, which measuring device is arranged in a measuring line connecting the valve housing with the valve rod
Implementation Method 2
The valve rod is electrically connected to the valve housing through a contact device
Data Source
AI summary
The invention relates to a control valve for adjusting a process fluid flow of a process plant, comprising a valve housing (8) with a valve seat (14) and a valve member (16) connected to a valve rod (18), which cooperates with the valve seat (14) for opening and closing the control valve (2), wherein the valve rod (18) is electrically connected to the valve housing (8) through a contact device (42, 43, 45). The invention is characterized in that a measuring device (26) for the ohmic transition resistance measurement of the contact device (42, 43, 45) is provided, and that the measuring device (26) is arranged in a measuring line (24) that connects the valve housing (8) to the valve rod (18).