Control Valve Stick-Slip Detection Using Online Position Diagnostics
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Solution Overview
Problem
Existing systems for detecting stick-slip in control valves are inefficient due to offline analysis and misdiagnosis, leading to inadequate timing and reliability in identifying the phenomenon, which results in valve wear and process instability.
Innovation Solution
A method and system for performing online diagnostics that processes setpoint and position data in real-time to detect stick-slip cycling by segmenting time into regions, calculating areas between setpoints and positions, and comparing these to threshold levels to identify consecutive exceedances, providing immediate detection and recommendations for correction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If offline analysis of collected data is used to detect stick-slip, then device complexity is reduced, but detection timing and reliability deteriorate
Solution Approach 1:
The system pre-calculates and stores expected valve position values based on setpoint data before actual operation. During real-time operation, these pre-computed reference values are immediately available for comparison with actual position measurements, enabling rapid stick-slip detection without complex real-time calculations.
Solution Approach 2:
The patent replaces manual offline data analysis with an automated computer-based system that performs real-time comparisons between expected and actual valve positions. This substitution of automated computational analysis for manual review dramatically improves detection reliability and timing while maintaining manageable system complexity through algorithmic simplicity.
2Measurement precision
If manual review of collected data is performed to determine stick-slip characteristics, then measurement precision is improved, but loss of time increases
Solution Approach 1:
The system continuously compares actual valve position measurements with expected position values in real-time during valve operation. This continuous monitoring ensures that stick-slip events are detected immediately when they occur, eliminating the time delay inherent in periodic manual data review while maintaining precise detection through consistent comparison criteria.
Solution Approach 2:
The system automatically performs the entire detection process without requiring operator intervention. The computer automatically retrieves setpoint data, calculates expected positions, compares with actual measurements, and identifies stick-slip events. This automation eliminates manual review time while maintaining detection precision through consistent algorithmic application.
3Ease of operation
If offline data analysis is used, then ease of operation is improved, but productivity deteriorates
Solution Approach 1:
The patent replaces manual data analysis operations with automated computer-based processing. The system automatically retrieves data, performs calculations, and identifies stick-slip events without operator involvement in the analysis process. This automation dramatically increases detection speed and productivity while keeping the system easy to operate through simple data collection and automatic reporting.
Solution Approach 2:
The detection system operates autonomously, self-managing the entire detection workflow from data collection to analysis and event identification. The computer system serves itself by automatically processing its own operational data without requiring external manual intervention, thereby maximizing detection speed while maintaining operational simplicity through automated workflows.
Data Source
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AI summary
A method of performing online diagnostics for a valve includes receiving valve information while the valve is in operation. The valve information includes setpoint data and position data associated with the valve. The method further includes processing the setpoint data and the position data at a plurality of time intervals, and detecting an occurrence of a stick-slip based on the processing.