Coriolis Pick-Off Signal Monitoring for Magnetic Field Interference
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Solution Overview
Problem
Existing Coriolis flowmeters struggle to detect and compensate for the effects of external magnetic fields, which can cause inaccuracies in flow measurements.
Innovation Solution
A Coriolis flowmeter system that includes a method to detect external magnetic fields by monitoring changes in pick-off sensor voltages and phase shifts, using independent signals to differentiate between magnetic interference and actual flow conditions, and applies a tamper correction factor to adjust flow rate measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If external magnetic fields are present near the pick-off sensors, then the pickoff voltage and phase shift change rapidly, but the flow measurement accuracy deteriorates
Solution Approach 1:
The patent detects external magnetic field interference by monitoring changes in pick-off sensor voltages and phase shifts that occur when magnets are placed near the sensors. This harmful interference is converted into a detectable signal that triggers correction factors, transforming the problem into a solution by using the interference itself as the detection mechanism.
Solution Approach 2:
The system continuously monitors pick-off sensor signals for indications of external magnetic fields and applies correction factors in real-time. The meter electronics provides feedback by comparing expected vs. actual sensor readings and adjusts measurements accordingly, creating a closed-loop system that compensates for magnetic interference.
2Productivity
If pick-off sensors are used to detect flow, then flow rate can be measured, but external magnetic fields cause voltage and phase shift changes that corrupt the measurement
Solution Approach 1:
The patent uses the magnetic field-induced changes in pick-off sensor behavior as a detection mechanism. By monitoring voltage and phase shift variations, the system identifies when external magnets are present and applies appropriate correction factors, converting the harmful effect into useful detection information.
Solution Approach 2:
The system introduces an intermediary detection layer that monitors the pick-off sensor signals for magnetic field indicators before final flow calculation. This intermediary step separates the raw sensor data from the final measurement, allowing magnetic interference to be identified and corrected without corrupting the primary flow measurement function.
3Adaptability or versatility
If a magnet is placed proximate a pick-off, then the sensor voltage and phase shift change rapidly, but the system cannot distinguish between magnetic interference and actual flow changes
Solution Approach 1:
The patent transforms the ambiguous signal changes caused by external magnets into a useful detection feature. By establishing characteristic patterns of magnetic interference (specific voltage and phase shift change patterns), the system can distinguish magnetic effects from actual flow changes, converting measurement corruption into a reliable detection mechanism.
Solution Approach 2:
The system replaces physical isolation methods (such as magnetic shielding) with an electronic detection and correction approach. Instead of mechanically preventing magnetic field interference, the patent uses electronic monitoring of sensor signals and computational correction factors to eliminate the need for complex physical barriers.
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
The system effectively detects and corrects for external magnetic interference, ensuring accurate flow rate measurements by triggering alarms and applying correction factors, thereby maintaining measurement integrity.
Implementation Method 1
The driver may comprise one of many well-known arrangements; however, 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) at a desired conduit amplitude and frequency.
Implementation Method 2
It is also known in the art to provide the pickoffs as a magnet and coil arrangement very similar to the driver arrangement.
Implementation Method 3
When a strong external magnet is placed proximate a pickoff, a few effects are observable. First, the pickoff voltage will either rapidly drop or increase. Second, the phase shift between pickoffs will either rapidly drop or increase.
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 (103A, 103B) in a first bending mode, and to receive signals from the pick-off sensors (105, 105′). The meter electronics (20) is configured to indicate a presence of an external magnetic field.