Magnetic Inductive Flow Meter with Segmented Tube Sections
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Solution Overview
Problem
Magnetic-inductive flowmeters face challenges in achieving accurate flow measurements due to factors like fluid conductivity, flow velocity, and flow profile, particularly in the transition range between laminar and turbulent flow, leading to measurement deviations and scatter.
Innovation Solution
A measuring tube with multiple sections of varying diameters and geometries, equipped with multiple magnet systems and electrode pairs, and an electronics unit that determines the flow velocity and profile to select the optimal section for measurement outside the transition area between laminar and turbulent flow, using fluid-specific parameters to compensate for inaccuracies and manage noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single measuring tube section is used, then the device complexity is low, but the measurement precision deteriorates due to transition area between laminar and turbulent flow
Solution Approach 1:
The measuring tube is divided into multiple sections with different cross-sectional areas. Each section creates different flow velocities at the same flow rate, allowing the system to operate outside the transition area between laminar and turbulent flow for improved measurement accuracy.
Solution Approach 2:
Different sections of the measuring tube have different geometric properties (cross-sectional areas) to create locally optimized flow conditions. This allows the system to adapt to different flow rates by selecting the appropriate section, ensuring measurements are always taken under optimal flow profile conditions.
2Measurement precision
If multiple pairs of measuring electrodes are used, then the measurement precision is improved by reducing measurement scatter, but the device complexity increases
Solution Approach 1:
Multiple pairs of measuring electrodes are distributed across different sections of the measuring tube. Each electrode pair independently measures the flow, and the electronics unit selects or combines measurements from different sections to optimize the signal-to-noise ratio and reduce measurement scatter.
3Measurement precision
If the flow velocity is increased to improve the measurement signal, then the measurement precision improves, but harmful factors increase due to cavitation and turbulence
Solution Approach 1:
The system changes the geometric parameter (cross-sectional area) of the measuring tube sections rather than increasing flow velocity. By using smaller cross-sectional sections, the system achieves higher flow velocities and stronger measurement signals without causing cavitation or turbulence, as the velocity increase is achieved through geometry rather than pressure increase.
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 measurement accuracy by optimizing flow velocity ranges and reducing noise, especially in fluids with low conductivity, by selecting the appropriate section based on flow profile and conductivity, thereby minimizing measurement errors.
Implementation Method 1
The measuring principle is based on Faraday's law of magnetic induction and is known from various publications. A magnetic field of constant strength over time is generated essentially perpendicularly to the direction of flow of the conductive fluid by means of a magnet system attached to a partial section of the measuring tube. As a result, the ions present in the flowing fluid are deflected in opposite directions.
Implementation Method 2
The electrical voltage resulting from this charge separation is tapped off by means of at least one pair of measuring electrodes which is also fastened in the measuring tube section. The voltage picked off is proportional to the flow velocity of the fluid and therefore proportional to the volume flow.
Data Source
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AI summary
Apparatus (1) for measuring the flow rate of a flowing fluid according to the magnetoinductive measurement principle, having a measuring tube (3) with at least two sections (11, 11') following one another in the direction of flow of the fluid, wherein the sections (11, 11') differ in terms of the diameter and/or the geometry of the cross-sectional area, at least one magnetic system (9, 9') having at least two coils for generating a magnetic field (10) substantially perpendicular to the direction of flow of the fluid, at least two measuring electrode pairs (8, 8') for tapping off the induced voltage, wherein at least one measuring electrode pair (8) is arranged in a first section (11) and a second measuring electrode pair (8') is arranged in a second section (11'), wherein each measuring electrode pair (8, 8') comprises a first measuring electrode and a second measuring electrode, wherein the measuring electrodes are opposite in or on the measuring tube and the connecting line of the measuring electrodes is oriented perpendicular to the tube axis and perpendicular to the magnetic field (10), and an electronic unit (6) for signal acquisition and/or evaluation and for supplying the coils, wherein the electronic unit (6) is configured in such a manner that it determines the flow velocity of the fluid and/or the flow rate for at least one section (11, 11') from the induced voltage.