Conductive Sheath for Microwave Flow Meter Backscatter
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Solution Overview
Problem
Non-contact flow meters for particulate streams face errors due to backscatter from dust clouds formed in collection bins, leading to inaccurate readings, especially when the delivery systems differ between factory calibration and actual commercial installations.
Innovation Solution
A Doppler-radar sensor system with a unique flow tube and a microwave-transparent membrane, combined with a conductive sheath reflective to microwaves at the exit end of the conduit, ensures that only particulate matter contributes to backscattered energy, reducing errors by minimizing dust cloud interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a non-contact flow meter is used to measure particulate stream flow, then measurement accuracy is improved and product contamination is prevented, but backscatter from dust clouds in the collection bin causes erroneous readings
Solution Approach 1:
The patent extracts and eliminates the harmful backscatter component by using signal processing techniques to separate the desired Doppler shift signal from the unwanted backscatter interference. The system isolates the useful information (particulate matter motion) from the harmful information (dust cloud backscatter) through careful signal analysis and processing.
Solution Approach 2:
The patent introduces an intermediary signal processing system that acts as a mediator between the microwave transmitter/receiver and the final measurement. This intermediary processing stage filters out the backscatter interference and extracts only the relevant flow information, allowing accurate measurement despite the presence of dust clouds in the collection bin.
2Measurement precision
If the flow meter is calibrated at the factory with a specific delivery system, then measurement accuracy is ensured under calibration conditions, but measurement errors occur when installed in different commercial settings with different delivery systems
Solution Approach 1:
The patent applies parameter changes by allowing the measurement system to adapt to different delivery system configurations through adjustable calibration parameters. The system can be recalibrated or have its parameters adjusted to account for variations in delivery system characteristics, maintaining measurement accuracy across different installation environments without requiring physical modification of the flow meter itself.
3Measurement precision
If a conductive sheath reflective to microwaves is placed at the exit end of the conduit, then backscatter from dust clouds is minimized, but device complexity increases
Solution Approach 1:
The patent employs a thin conductive sheath or reflective barrier placed at the exit end of the conduit. This thin film or shell structure is sufficient to reflect microwave energy and prevent dust cloud backscatter interference without requiring complex or bulky components. The solution achieves effective backscatter reduction through a simple, thin reflective layer rather than a complex structural modification.
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 solution provides accurate and consistent mass flow rate measurements by ensuring that only the particulate matter contributes to the backscattered energy, reducing the impact of dust clouds and maintaining measurement integrity across different installation settings.
Implementation Method 1
A Doppler-radar sensor... transmits a signal... detects the magnitude and the Doppler shift of the electromagnetic signal that is reflected by material moving along the process flow
Implementation Method 2
at least a portion of the radio waves are backscattered by the particulate matter in the path of the radiated radio waves and are picked up by the receiver
Implementation Method 3
a conductive sheath reflective to microwaves at the exit end of the conduit
Data Source
AI summary
Method for eliminating or reducing reading errors of a non-contact microwave solids flow meter measuring solid particulate flow. The method is particularly suitable for calibration procedures prior to installation into an operating system. The flow meter is very sensitive and may pick up backscatter from dust and/or particulate clouds of the particulate product that builds up in the space above the collected particulate of the delivered product in the collecting bin. Readings that include backscatter from the dust cloud are in excess of the actual flow rate. The invention reduces or eliminates backscatter readings that include the particulate dust cloud by attaching a sheath reflective to backscatter energy and made for example from wire mesh to the delivery end of the output duct. The sheath extends toward the build up of the particulate material. During the calibration procedure, the reflective sheath is continuously moved so that it does not contact the material as it builds up.