Vibratory Flowmeter Stiffness Verification via Pole-Residue Model
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Vibratory flowmeters face challenges due to changes in flowtube stiffness over time, such as corrosion or erosion, which affect the accuracy of mass flow rate measurements, and existing diagnostic methods struggle to detect coating or plugging issues, especially when the coating density is similar to the process fluid, leading to potential false alarms and reduced meter reliability.
Innovation Solution
The implementation of meter electronics that vibrate the flowmeter assembly in a single mode, compute frequency response functions, and fit them to a pole-residue model to determine meter mass values, allowing for verification of proper operation and detection of changes in stiffness and mass deviations, thereby providing a 'go/no go' indication for coating, erosion, or other damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional calibration methods are used to determine mass flow rate, then the measurement process is simple, but the accuracy deteriorates when flowtube stiffness changes due to corrosion or erosion
Solution Approach 1:
The system dynamically adapts by continuously monitoring the flowtube's vibrational characteristics (natural frequency, damping ratio) and adjusting measurements in real-time. This allows the system to compensate for stiffness changes due to corrosion or erosion, maintaining measurement accuracy without requiring periodic recalibration or shutdowns.
Solution Approach 2:
The system monitors changes in vibrational parameters (natural frequency, damping ratio, mode shapes) to detect and compensate for flowtube degradation. By tracking these parameter changes over time, the system can distinguish between actual flow measurements and changes caused by corrosion or erosion, thereby maintaining measurement precision.
2Reliability
If existing diagnostic methods are used to detect coating or plugging, then the system operates with standard monitoring, but false alarms increase when coating density is similar to process fluid density
Solution Approach 1:
The system transitions from single-frequency monitoring to multi-frequency vibrational analysis. By exciting the flowtube at multiple frequencies and analyzing the resulting mode shapes and resonance patterns, the system can detect coating even when its density matches the process fluid, as the coating alters the distributed mass and stiffness characteristics of the flowtube.
Solution Approach 2:
The same vibrational monitoring system used for flow measurement also performs diagnostic functions for coating and plugging detection. By analyzing multiple vibrational parameters (natural frequency, damping ratio, mode shapes) from the same sensor data, the system achieves multiple objectives without adding separate diagnostic hardware.
3Difficulty of detecting and measuring
If comprehensive monitoring of flowtube conditions is implemented, then detection capability improves, but system complexity and cost increase
Solution Approach 1:
The flowtube itself serves as the sensing element for both flow measurement and condition monitoring. The same structural component that conveys the fluid also provides the vibrational data needed to detect corrosion, erosion, coating, and plugging, eliminating the need for separate sensors or monitoring systems.
Solution Approach 2:
The system combines flow measurement and diagnostic monitoring functions into a single integrated system. By using the same excitation mechanism and sensors for both purposes and processing multiple parameters from the same data source, the system achieves comprehensive monitoring without proportionally increasing complexity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enhances the detectability of flow calibration factor changes, minimizes false alarms, and ensures accurate verification of flowmeter operation, including the detection of coating and other damage, thereby maintaining measurement accuracy and reliability.
Implementation Method 1
vibrate the flowmeter assembly in a single mode using a driver
Implementation Method 2
determine first and second response voltages generated by first and second pickoff sensors
Implementation Method 3
compute frequency response functions for the determined first and second response voltages from the determined single mode current
Implementation Method 4
fit the generated frequency response functions to a pole-residue model to generate a meter mass value
Implementation Method 5
During flow, the vibrating tube and the flowing mass couple together due to Coriolis forces, causing a phase shift in the vibration between the ends of the tube
Data Source
AI summary
A vibratory flowmeter (5) for meter verification is provided, including meter electronics (20) coupled to the first and second pickoff sensors (170L, 170R) and coupled to a driver (180), with the meter electronics (20) configured to: vibrate the flowmeter assembly (10) in a single mode using the driver (180), determine a single mode current (230) of the driver (180) and determine first and second response voltages (231) generated by the first and second pickoff sensors (170L, 170R), respectively, compute frequency response functions for the determined first and second response voltages (231) from the determined single mode current (230), fit the generated frequency response functions to a pole-residue model, and verify proper operation of the vibratory flowmeter (5) using the meter stiffness value (216), residual flexibility (218), and the meter mass (240) in embodiments.