Control Valve Diagnosis Using Actuator Position Changes
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Solution Overview
Problem
Existing methods for diagnosing changes in control valves require additional sensors or complex monitoring systems, failing to account for the operating point of the valve and often lead to unnecessary complications.
Innovation Solution
A method that records data on the position of the actuator at regular intervals, determines characteristics such as the operating point and working range, and compares these over time to diagnose changes without additional sensors, allowing for early detection of issues like wear or incorrect design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If additional force sensors or scanning devices are used to detect valve wear, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The control valve uses its own actuator position data to diagnose wear and malfunctions, eliminating the need for external sensors. The valve monitors itself by analyzing deviations between commanded and actual positions during operation, making the system self-diagnostic without additional hardware.
Solution Approach 2:
The patent introduces an intermediary diagnostic method that uses existing actuator position data as a mediator to infer valve wear conditions. Instead of directly measuring wear with sensors, the system uses position deviations as an indirect indicator of valve health, avoiding complex measurement hardware.
2Reliability
If complex plant control systems are used to monitor valve operation, then reliability is improved, but device complexity increases
Solution Approach 1:
The patent extracts the diagnostic function from complex plant control systems and implements it directly within the control valve itself. By taking out the monitoring logic from the central control system and placing it in the valve, the solution maintains reliable monitoring while significantly reducing overall system complexity.
Solution Approach 2:
The monitoring function is segmented into discrete diagnostic steps including data collection, operating point determination, deviation calculation, and malfunction diagnosis. This segmentation allows the complex monitoring task to be broken down into manageable components that can be executed by the valve's own controller without requiring complex external systems.
3Measurement precision
If additional sensors are installed to monitor valve position, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The control valve utilizes its existing actuator position feedback system to monitor its own operation. The valve's controller already receives position data from the actuator for control purposes, and this same data is repurposed for diagnostic monitoring, eliminating the need for separate position sensors.
Solution Approach 2:
The actuator position data serves multiple functions: it is used both for controlling the valve operation and for diagnosing valve wear and malfunctions. This multi-functionality allows the system to achieve precise monitoring without adding dedicated sensors, as the existing position data is put to dual use.
Data Source
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AI summary
The invention relates to a method for diagnosing possible causes of changes in at least one control valve, in a system comprising the control valve or in a process performed in the system, wherein the position of the actuator is sensed at least in a first time interval and in a second time interval, a working point or working range from the first time interval and from the second time interval are determined and compared, and possible causes of changes in the at least one control valve, in the system or in the process are diagnosed on the basis of determined differences. Such a diagnosis does not require additional sensing equipment and allows emerging problems or undesirable developments to be identified solely from the operating state of the valve.