Control Valve Partial-Stroke Detection for Deterioration Diagnosis
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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 lack effective diagnostic methods for actuator and valve deterioration, especially in systems without analog or discrete position transmitters.
Innovation Solution
A method involving a valve controller that monitors steady-state conditions and initiates a partial stroke command to diagnose valve and actuator functionality, using feedback signals from sensors like suction pressure, discharge pressure, and flow meters to detect changes and generate an alarm if no movement occurs within a predefined time, thereby identifying latent failures and degradation.
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 degraded or non-responsive due to foreign material buildup and increased friction
Solution Approach 1:
The system implements periodic valve cycling by automatically initiating a valve stroke command at predetermined intervals. This periodic action prevents foreign material buildup and maintains valve responsiveness without requiring continuous operation, thus resolving the contradiction between operational stability and valve reliability.
Solution Approach 2:
The system performs preliminary diagnostic testing by attempting to actuate the valve before critical failure occurs. The controller monitors whether the valve responds to actuation commands within expected timeframes, enabling early detection of deterioration and preventing complete valve seizure.
2Measurement precision
If manual evaluation of valve response is performed, then valve deterioration can be detected, but human error occurs and production may be disrupted
Solution Approach 1:
The system performs self-diagnosis by automatically monitoring its own valve actuation response. The controller initiates valve stroke commands and evaluates the valve's response without human intervention, eliminating human error while maintaining accurate deterioration detection. The system serves itself by detecting its own latent failures.
Solution Approach 2:
The system implements closed-loop feedback by monitoring the valve's response to actuation commands and comparing it against expected performance criteria. The controller receives feedback signals indicating whether the valve moved within the predetermined time period, enabling automatic detection of valve deterioration without manual evaluation.
3Reliability
If a valve stroke command is initiated to test valve response, then latent failures can be detected, but system disturbance may occur
Solution Approach 1:
The system applies partial action by initiating valve stroke commands of limited duration and magnitude sufficient only for diagnostic purposes. The valve is actuated just enough to test responsiveness without requiring full operational movement, thereby detecting latent failures while minimizing system disturbance.
4Reliability
If diagnostic testing is performed frequently, then valve deterioration is detected early, but system productivity decreases due to repeated interruptions
Solution Approach 1:
The system performs diagnostic testing at predetermined intervals that balance early failure detection with minimal disruption to production. By spacing tests periodically rather than continuously, the system maintains productivity while still detecting valve deterioration before it causes complete failure.
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.