Control Valve Partial-Stroke Detection for Degradation 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 degradation due to foreign material buildup, resulting in increased friction or seizure, and existing diagnostic methods are prone to human error and process disturbances.
Innovation Solution
A system and method for automatically diagnosing actuator and valve degradation by monitoring steady-state conditions and initiating a partial valve stroke using feedback signals from sensors, allowing for the detection of valve movement without manual intervention and reducing system disruption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If manual diagnostic testing is performed by moving the valve, then valve degradation can be detected, but it causes process disturbance and production loss
Solution Approach 1:
The system performs partial valve strokes (e.g., 10-20% movement) rather than full valve movements for diagnostic testing. This partial action is sufficient to detect valve degradation through feedback signal analysis while minimizing process disturbance and maintaining production continuity.
Solution Approach 2:
The system continuously monitors feedback signals during normal operation to detect valve degradation before it causes complete failure. By performing preliminary detection during steady-state conditions, the system avoids the need for disruptive manual testing and enables proactive maintenance scheduling.
2Stability of the object's composition
If the valve remains stationary for extended periods, then system stability is maintained, but the valve deteriorates due to foreign material buildup and friction
Solution Approach 1:
The system implements periodic valve exercise by automatically initiating partial strokes at predetermined intervals during steady-state operation. This periodic movement prevents foreign material buildup and friction without requiring continuous motion, thereby maintaining both system stability and valve reliability through automated maintenance.
3Measurement precision
If automated diagnostic testing is implemented, then detection accuracy improves and human error is reduced, but system complexity increases
Solution Approach 1:
The system utilizes existing feedback signals from the control system to detect valve degradation automatically. By analyzing changes in feedback signal characteristics (position, pressure, flow) during partial valve strokes, the system achieves high detection accuracy without requiring additional complex sensing equipment or manual intervention.
4Reliability
If full valve movement is performed for testing, then comprehensive valve function is verified, but process disturbance and production loss increase
Solution Approach 1:
The system performs partial valve strokes (e.g., 10-20% movement) rather than full valve movements for diagnostic testing. This partial action is sufficient to detect valve degradation through feedback signal analysis while minimizing process disturbance and maintaining production continuity.
Data Source
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.