Control Valve Obstruction Detection from Setpoint-Position Deviations
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Solution Overview
Problem
Control valves often experience unintentional or intentional obstructions, which can disrupt plant operations, and existing systems lack effective methods for detecting and addressing these obstructions in real-time.
Innovation Solution
A system that collects and analyzes operational data from control valves to detect obstructions by determining a control zone based on setpoint and position data, alerting operators of high or low obstructions, and allowing for automatic corrective actions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If no obstruction detection system is implemented, then the system remains simple and costs are low, but plant operations are disrupted when obstructions occur
Solution Approach 1:
The system continuously monitors control valve position and compares it against expected position based on setpoint changes. When the actual position deviates from expected position beyond a threshold, an obstruction is detected and an alarm is generated, providing real-time feedback about valve status to operators
Solution Approach 2:
The system uses existing control valve position data already being collected by the control system, rather than requiring additional sensors or measurement devices. The obstruction detection logic processes this existing data to identify obstructions, allowing the system to self-monitor using resources already available
2Loss of time
If obstruction detection is implemented, then obstructions are detected early, but the system complexity increases
Solution Approach 1:
The system applies a simplified detection approach by monitoring only whether the control valve position reaches expected targets within specified time intervals, rather than analyzing complete valve performance characteristics. This partial monitoring approach detects obstructions quickly without requiring complex diagnostic algorithms
Solution Approach 2:
The detection process is divided into discrete time intervals where the system checks whether the control valve has reached expected positions at specific moments. This segmentation of continuous monitoring into discrete checkpoints simplifies the detection logic while maintaining effective obstruction detection
Data Source
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AI summary
A system receives a plurality of data samples associated with a control valve with each of the plurality of data samples associated with a setpoint and a position. A first subset of the data samples that are in a control zone associated with normal operation of the control valve is determined. In a case that a second subset of the data samples are determined to be (i) not in the first subset and (ii) close to a minimum position of the plurality of data samples and (iii) have setpoints less than their associated positions, an alert associated with a low obstruction is indicated. In a case that a second subset of the data samples are determined to be (i) not in the first subset and (ii) close to the maximum position of the plurality of data samples and (iii) have setpoint greater than their associated position, an alert is indicated.