Digital Valve Positioner Testing for Online Seating Integrity
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Solution Overview
Problem
Control valves, especially sliding stem valves, face integrity issues due to wear and corrosion, requiring offline testing that is costly and time-consuming, as conventional methods only allow evaluation during shutdown or bypass mode.
Innovation Solution
A system and method for executing online valve seating integrity tests by queuing test requests and monitoring valve positions, allowing for sensor data collection without taking the valve offline, using a digital valve positioner and position sensors to compare test start points with current valve positions and generate results.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If offline testing is performed to assess valve seating integrity, then measurement precision is improved, but loss of time and productivity deteriorate due to required shutdowns
Solution Approach 1:
The system performs preliminary actions by continuously monitoring valve parameters (actuator position, stem position, valve position) during normal operation and pre-calculating expected relationships. When a test is requested, the data is already collected and ready for immediate analysis, eliminating the need to take the valve offline for data collection.
Solution Approach 2:
The monitoring system operates continuously during valve normal operation, maintaining data collection without interruption. This continuous monitoring ensures that when a seating integrity test is needed, the necessary data is already available, allowing the valve to remain in service and maintaining continuous productive operation.
2Measurement precision
If offline testing is performed to assess valve seating integrity, then measurement precision is improved, but maintenance costs increase due to shutdown requirements
Solution Approach 1:
The valve system performs self-diagnosis by using its own operational data (actuator position, stem position, valve position) to assess its own seating integrity. This eliminates the need for external testing equipment and personnel, allowing the system to monitor and evaluate itself continuously without requiring costly offline testing services.
Solution Approach 2:
By enabling continuous monitoring during normal operation, the system avoids the costly shutdowns required for traditional testing. The uninterrupted operation maintains productivity and eliminates the indirect costs associated with stopping the process, while still providing accurate seating integrity assessment.
3Device complexity
If conventional testing methods are used, then device complexity is reduced, but ease of operation deteriorates due to required bypass mode or isolation
Solution Approach 1:
The monitoring system serves multiple functions: it continuously tracks valve parameters for normal operation control, collects data for seating integrity assessment, and provides diagnostic information all through a single integrated system. This multi-functionality eliminates the need for separate testing equipment and complex bypass arrangements, simplifying the overall system while improving ease of operation.
Data Source
AI summary
Systems and methods may be provided to execute online tests of a valve in a digital valve positioner. The digital valve positioner may receive a request to execute a test of the valve, which specifies a test start point, and queue the request for execution. The digital valve positioner may subsequently receive a new setpoint for the valve. The digital valve positioner may further reposition the valve according to the new setpoint. The digital valve positioner may further, while the valve is being repositioned, compare the test start point to a current position of the valve, and in response to determining that the current position of the valve has reached the test start point, collect sensor data indicative of the operation of the valve, to generate results of the test.