Control Valve Performance Evaluation Using Differential Pressure
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Solution Overview
Problem
Current methods for evaluating control valve performance are inconsistent and invasive, relying on operator experience and manufacturer-provided data that does not account for installed valve characteristics, leading to potential process disruptions due to performance variations caused by leakage or bypass issues.
Innovation Solution
A method and system for establishing an expected flow rate through a control valve using measured differential pressure and valve flow coefficient, allowing for real-time, non-invasive performance evaluation by comparing actual and expected flow rates within a tolerance range, applicable to both linear and equal percentage valves.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If offline stroke tests are performed to evaluate control valve performance, then measurement precision is improved, but productivity deteriorates due to process downtime
Solution Approach 1:
The system performs preliminary calculations of expected flow rate using valve coefficients and differential pressure measurements before actual performance evaluation is needed. This allows the control valve to be assessed continuously during normal operation without requiring shutdowns for testing.
Solution Approach 2:
The patent replaces the mechanical offline stroke test system with a computational system that uses flow rate formulas and differential pressure measurements. This substitution eliminates the need for physical valve shutdown and manual testing, enabling continuous process operation while maintaining evaluation accuracy.
2Adaptability or versatility
If operator experience is relied upon to build mental models for diagnosing control valve performance, then adaptability is improved, but measurement precision deteriorates due to inconsistency between operators
Solution Approach 1:
The control valve performance evaluation system is self-sufficient, using objective measurements of differential pressure and valve coefficients to calculate expected flow rates. This eliminates the need for operator mental models and subjective judgment, providing consistent results regardless of operator experience level.
Solution Approach 2:
The system continuously compares actual flow rate measurements with calculated expected flow rates, providing objective feedback on valve performance. This feedback mechanism replaces subjective operator assessment with quantifiable, consistent criteria that can be automatically evaluated.
3Ease of operation
If manufacturer provided statistics are used for comparison, then ease of operation is improved, but measurement precision deteriorates because installed characteristics are not accounted for
Solution Approach 1:
The system accounts for local installed characteristics of each specific control valve by measuring its actual differential pressure and using its specific valve flow coefficient. This localized approach replaces generic manufacturer statistics with valve-specific data, improving evaluation accuracy while maintaining ease of operation through automated calculations.
Data Source
AI summary
A method for providing a system for establishing a control valve performance in a process operation. The system includes establishing an expected flow rate for a control valve by measuring a differential pressure between an upstream and downstream position of a control valve of interest and using the formulaQ=Cv×φ(x)×ΔPG,measuring an actual flow rate across the control valve, comparing the actual flow rate with the expected flow rate to determine the difference in value between the actual and expected flow rate, determining if the difference is within an acceptable range of values from the expected flow rate and establishing the performance of the control valve.