Flow Meter Electronics Stiffness Compensation
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Solution Overview
Problem
Coriolis mass flow meters face accuracy issues due to changes in stiffness characteristics caused by erosion, corrosion, or other factors, which affect the Flow Calibration Factor and require frequent calibration, making it costly and time-consuming to maintain measurement accuracy.
Innovation Solution
The method involves automatically adjusting internal filtering in meter electronics to account for changes in gain decay variables, such as pickoff voltage, drive currents, and temperature, allowing for real-time stiffness calculations without the need for a calibration test stand or special equipment, by measuring and comparing slopes over time and adjusting filters accordingly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If flow meters are used to measure mass flow rate, then measurement capability is provided, but accuracy deteriorates over time due to stiffness changes from erosion and corrosion
Solution Approach 1:
The system continuously monitors stiffness characteristics by measuring natural frequencies of the flow tubes and automatically adjusts the flow calibration factor based on detected changes. This closed-loop feedback mechanism compensates for stiffness variations caused by erosion and corrosion, maintaining measurement accuracy without manual recalibration.
Solution Approach 2:
The system dynamically changes the flow calibration factor parameter based on measured stiffness characteristics. By detecting shifts in natural frequencies that indicate stiffness changes, the system automatically updates the calibration factor to compensate for these changes, thereby maintaining accurate mass flow rate measurements despite environmental degradation.
2Measurement precision
If frequent calibration is performed to maintain accuracy, then measurement precision is maintained, but time and cost increase
Solution Approach 1:
The flow meter performs self-calibration by automatically detecting its own stiffness characteristics through natural frequency measurements and adjusting its flow calibration factor accordingly. This eliminates the need for external calibration equipment and manual intervention, allowing the device to maintain accuracy autonomously without requiring scheduled calibration downtime.
Solution Approach 2:
The system continuously monitors stiffness characteristics and adjusts calibration factors in real-time operation, rather than requiring periodic shutdowns for calibration. This continuous adaptation ensures measurement precision is maintained without interrupting the useful action of flow measurement, thereby eliminating calibration-related time losses.
3Reliability
If stiffness monitoring is implemented to detect changes, then reliability is improved, but device complexity increases
Solution Approach 1:
The existing flow tube structure serves multiple functions: it acts as both the flow conduit and the sensing element for stiffness monitoring. The natural frequency measurements used to detect stiffness changes are derived from the same vibrational characteristics already utilized for flow measurement, eliminating the need for separate monitoring hardware and reducing overall system complexity.
Solution Approach 2:
The system replaces complex mechanical calibration mechanisms with electronic sensing and computational methods. By using electrical measurements of natural frequencies and algorithmic adjustment of calibration factors, the system achieves reliable stiffness monitoring without mechanical wear components or complex adjustment mechanisms.
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 enables continuous, accurate mass flow rate measurements by tracking stiffness changes and adjusting filtering settings, thereby maintaining high accuracy without the need for frequent recalibration, reducing costs and time associated with field calibration.
Implementation Method 1
A flow tube is forced to vibrate at a resonant frequency, where the resonant frequency of the tube is proportional to the density of the fluid in the flow tube
Implementation Method 2
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
Implementation Method 3
measuring a decay characteristic of the flow tube vibration
Data Source
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AI summary
A method for verifying accurate operation for a flow meter (5) is provided. The method entails receiving a vibrational response from the flow meter (5), wherein the vibrational response comprises a response to a vibration of the flow meter (5) at a substantially resonant frequency. At least one gain decay variable is measured. It is then determined whether the gain decay variable is outside a predetermined range. A filter used in a stiffness calculation is adjusted if the gain decay variable is outside the predetermined range.