Coriolis Flow Meter Bubble Detection via Anti-Symmetrical Vibration
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Solution Overview
Problem
Existing methods for determining the passage time of components in a heterogeneous medium within a Coriolis mass flow meter are inadequate, as they fail to accurately distinguish between different bubble sizes or groups of bubbles, leading to incorrect passage time measurements.
Innovation Solution
The method involves exciting a Coriolis mass flow meter's measuring tube with a signal at the natural frequency of an anti-symmetrical bending vibration mode, sensing the signal amplitude, and determining the characteristic passage time through spectral analysis and autocorrelation of the signal amplitude profiles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the passage time is determined based on damping of symmetrical bending vibration mode, then the occurrence of free bubbles can be recognized, but different bubble sizes or groups of bubbles simulate different passage times leading to measurement inaccuracy
Solution Approach 1:
The patent applies asymmetry by switching from monitoring symmetrical bending vibration mode to anti-symmetrical bending vibration mode. The anti-symmetrical mode exhibits different damping characteristics that are independent of bubble size, allowing accurate passage time measurement. The exciter is configured to excite anti-symmetrical modes specifically, and the vibration sensor detects the characteristic damping pattern that occurs when bubbles pass through, enabling reliable detection without the measurement precision problems of symmetrical mode monitoring.
2Measurement precision
If multi-frequency technology is used to correct vibrations of compressible media, then the influence of microbubbles can be corrected, but the correction algorithms fail for larger free bubbles
Solution Approach 1:
The patent changes the monitoring parameter from symmetrical bending vibration damping to anti-symmetrical bending vibration damping. This parameter change enables the system to detect both microbubbles and larger free bubbles accurately. The anti-symmetrical mode's damping characteristics provide a universal detection mechanism that works across different bubble size ranges, eliminating the need for separate correction algorithms for different bubble types.
3Speed
If the excitation signal uses natural frequency of bending vibration mode, then the measuring tube vibrations can be excited, but the vibration mode may not provide accurate passage time information
Solution Approach 1:
The patent dynamically selects which vibration mode to monitor based on the measurement requirements. While the exciter continuously excites the measuring tube at its natural frequency to maintain vibration, the system dynamically switches the monitoring focus to anti-symmetrical bending vibration mode when passage time measurement is required. This dynamic approach allows the system to maintain efficient vibration excitation while accessing the measurement capabilities of anti-symmetrical modes that provide accurate passage time information independent of bubble size.
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 allows for accurate determination of the characteristic passage time, independent of bubble size or other medium properties, thereby improving the measurement accuracy of flow velocity, volume flow rate, and mass flow rate.
Implementation Method 1
at least one exciter for exciting at least one bending vibration mode of the measuring tube
Implementation Method 2
Feeding an excitation signal to the exciter with a natural frequency of at least one bending vibration mode
Implementation Method 3
at least one vibration sensor for sensing the measuring tube vibrations
Implementation Method 4
the signal amplitude of the at least one first vibration sensor at the natural frequency of the first anti-symmetrical bending vibration mode is ascertained by means of a spectral analysis
Implementation Method 5
the characteristic passage time is ascertained by means of autocorrelation of the at least one first time profile of the signal amplitude at the natural frequency of the anti-symmetrical bending vibration mode
Implementation Method 6
Coriolis mass flow meter are particularly suitable for measuring mass flow rates
Data Source
AI summary
The method determines a characteristic passage time of a component of a flowing medium in a vibrating measuring tube of a Coriolis mass flow meter. The flow meter has the measuring tube, an exciter for exciting a bending vibration mode of the measuring tube, and a vibration sensor for sensing the measuring tube vibrations. The component is present inhomogenously in the medium and has a component density which deviates from an average density of the medium. The method includes feeding an excitation signal to the exciter with a natural frequency a bending vibration mode, ascertaining at least one first time profile of a signal amplitude of the first vibration sensor at a natural frequency of an anti-symmetrical bending vibration mode, and ascertaining the characteristic passage time on the basis of the first time profile of the signal amplitude at the natural frequency of the anti-symmetrical bending vibration mode.