Process Valve Diagnosis Using Displacement Feedback
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Solution Overview
Problem
Existing methods for monitoring process valve functionality in continuous operation fail to detect malfunctions early enough to prevent failures without interrupting the process plant's operation.
Innovation Solution
A diagnosis method using a displacement-measurement system to determine process actual data, which are compared with normalized process set data to identify deviations indicative of errors such as insufficient mains pressure, valve blocking, leakage, pressure surges, and running-time changes, without requiring additional sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If optical sensors and pressure detection devices are used to monitor valve function, then detection capability is improved, but device complexity increases and requires additional sensors
Solution Approach 1:
The existing displacement-measurement system serves dual purposes: controlling the valve and monitoring its function. The control unit compares commanded displacement values with actual displacement values from the same system, enabling self-diagnosis without additional sensors. This resolves the contradiction by making the existing system perform both control and monitoring functions.
Solution Approach 2:
The displacement-measurement system is made multi-functional by using it for both valve control and fault detection. The control unit processes both control commands and diagnostic comparisons using the same measurement data, eliminating the need for separate monitoring sensors while maintaining detection capability.
2Reliability
If continuous monitoring is implemented during normal operation, then reliability is improved, but productivity may worsen due to processing overhead
Solution Approach 1:
The control unit continuously receives actual displacement values from the displacement-measurement system and compares them with commanded values in real-time. This feedback mechanism enables continuous monitoring during normal operation without requiring separate processing systems, maintaining both reliability and productivity by integrating monitoring into the existing control loop.
Data Source
AI summary
A diagnosis method for continuous function monitoring of a process valve during normal operation. The diagnosis method includes the steps of determining process set data (S) with discrete-time process set values from an input signal supplied to the process valve, b) determining process actual data (s) with discrete-time process actual values using a displacement-measurement system assigned to the process valve, and c) analyzing the process actual data (s) dependent on the process set data (S) by comparing the process set data (S) and the process actual data (s) with each other to detect defined error states.