Control Valve Partial-Stroke Detection for Latent Actuator Failure
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Solution Overview
Problem
Control valves in turbo-compressor anti-surge and steam turbine applications often remain stationary for extended periods, leading to degraded or non-responsive conditions due to foreign material buildup, and existing diagnostic methods are either ineffective or prone to human error, especially for actuators without position transmitters.
Innovation Solution
A method involving a valve controller that monitors steady-state conditions and performs periodic or manually-initiated diagnostic tests by sending configurable partial-stroke signals to the actuator, allowing for the detection of valve movement without disrupting the system, even for actuators without analog or discrete position transmitters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the control valve remains in one position for extended periods, then the system operates stably, but the valve response becomes severely degraded or non-responsive due to foreign material buildup and increased friction
Solution Approach 1:
The system performs periodic diagnostic tests by automatically initiating small valve movements at predetermined intervals to prevent foreign material buildup and maintain valve responsiveness without disrupting normal stable operation
Solution Approach 2:
The system proactively performs valve exercise movements before the valve actually fails, detecting potential issues through monitored parameters during periodic tests and addressing them before they cause complete valve seizure
2Measurement precision
If manual diagnostic testing is performed to detect valve deterioration, then latent failures can be identified, but human error occurs and process disturbance or production loss may result
Solution Approach 1:
The control system automatically performs diagnostic tests and monitors valve response without human intervention, eliminating human error while maintaining accurate failure detection through programmed test sequences and automated parameter monitoring
Solution Approach 2:
The system monitors parameters during valve exercise movements and compares them against expected ranges to automatically detect valve deterioration, providing continuous feedback on valve health without requiring manual assessment
3Reliability
If a valve exercise movement is initiated to test valve responsiveness, then latent failures are detected, but system disturbance occurs and production losses may result
Solution Approach 1:
The system performs partial valve movements (small exercise movements) rather than full valve strokes, providing sufficient diagnostic information to detect latent failures while minimizing system disturbance and maintaining production continuity
Solution Approach 2:
Valve exercise tests are performed at predetermined intervals rather than continuously, allowing normal production to proceed uninterrupted between tests while still providing periodic verification of valve functionality
Data Source
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AI summary
Automatic testing for control valves is provided for diagnosing of actuators, including actuators not equipped with analog or discrete position transmitters. A valve controller confirms steady-state conditions for a turbo-compressor system that includes a control valve in a first position and sends, to an actuator for the control valve, a signal to initiate a partial valve stroke to move the control valve away from the first position. The valve controller receives feedback signals from sensors in the turbo-compressor system and monitors the feedback signals for a change from the steady-state conditions. When the monitoring detects a change from the steady-state conditions within a defined time period, the valve controller sends, to the actuator, a signal to return the control valve to the first position. When the monitoring does not detect a change from the steady-state conditions within the defined time period, the valve controller generates an alarm signal.