Coriolis Flowmeter Pick-Off Ratio for Magnetic Field Detection
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Solution Overview
Problem
Existing Coriolis flowmeters are susceptible to external magnetic field interference, which can manipulate flow readings, posing a risk in transaction integrity.
Innovation Solution
A Coriolis flowmeter system that detects external magnetic fields by monitoring pick-off sensor voltages and determining a pick-off ratio (PORATIO), comparing it against a predetermined limit (POLIMIT), and indicating the presence of an external magnetic field if PORATIO falls outside this limit, using additional process variables to reduce false positives.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a magnet and coil arrangement is used for pick-off sensors, then the flowmeter can generate voltage signals to measure mass flow, but the magnetic field becomes susceptible to external magnetic field interference that can manipulate flow readings
Solution Approach 1:
The patent implements a feedback mechanism by continuously monitoring the pick-off sensor voltages and calculating the pick-off ratio. The system compares the calculated PORATIO against predetermined limits and provides feedback by indicating external magnetic field interference when the ratio falls outside acceptable ranges. This closed-loop monitoring approach enables real-time detection and correction of measurement errors caused by magnetic interference.
Solution Approach 2:
The patent introduces an intermediary detection mechanism - the pick-off ratio calculation - that serves as a mediator between the raw sensor voltages and the final flow measurement. By using the ratio of pick-off voltages as an intermediate parameter, the system can identify magnetic field interference without directly measuring the magnetic field itself, thus protecting the integrity of the flow measurement.
2Reliability
If external magnetic field detection is implemented by monitoring pick-off sensor voltages and calculating PORATIO, then external magnetic field interference can be detected, but the system complexity increases
Solution Approach 1:
The patent achieves multi-functionality by using the existing pick-off sensor voltage signals for dual purposes: (1) the traditional purpose of measuring mass flow through Coriolis force detection, and (2) the new purpose of detecting external magnetic field interference through PORATIO calculation. This eliminates the need for separate detection hardware, as the same sensor signals serve both measurement and security functions simultaneously.
Solution Approach 2:
The system performs self-diagnosis by using its own operational signals (pick-off voltages) to detect anomalies. The pick-off ratio calculation is derived entirely from signals already present in the measurement system, requiring no external calibration or additional reference measurements. The flowmeter essentially monitors itself for magnetic interference using its existing sensor infrastructure.
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
Effectively detects external magnetic field interference, minimizing false readings and ensuring transaction integrity by providing accurate flow measurements.
Implementation Method 1
a magnet and an opposing drive coil have received great success in the flowmeter industry. An alternating current is passed to the drive coil for vibrating the conduit(s)
Implementation Method 2
As flowtubes vibrate, pickoff bobbin wires pass through a magnetic field of a magnet, which generates a voltage
Implementation Method 3
As material begins to flow through the conduit(s), Coriolis forces cause each point along the conduit(s) to have a different phase
Data Source
AI summary
A Coriolis flowmeter (5) is provided, the Coriolis flowmeter (5) comprising flow conduits (103A, 103B), having a driver (104), and pick-off sensors (105, 105′) connected thereto. A meter electronics (20) is configured to drive the driver (104) to oscillate the flow conduits (103 A, 103B), and to receive signals from the pick-off sensors (105, 105′). The meter electronics (20) is configured to capture voltages for both the pick-off sensors (105, 105′) and determine a PORATIO and determine whether the PORATIO falls within a predetermined POLIMIT. The presence of an external magnetic field is indicated if the PORATIO falls outside the predetermined POLIMIT.