Vibronic Flow Measurement With Multi-Mode Drive-Offset Compensation
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Solution Overview
Problem
Existing vibronic measuring systems face challenges in improving measurement accuracy and robustness, particularly in determining flow parameters with fluctuating viscosity and material properties, and require reduced technical effort for compensating phase differences due to drive offset and changing material parameters.
Innovation Solution
A vibronic measuring system with precise alignment of vibration exciter and sensors, utilizing multiple vibration modes and controlled drive frequencies to minimize drive offset, and employing advanced electronics for accurate determination of flow parameters, including mass flow and density, by compensating for phase differences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the vibration exciter is precisely aligned with the pipe to minimize drive offset, then measurement accuracy is improved, but manufacturing precision requirements increase
Solution Approach 1:
The patent applies preliminary action by performing a self-alignment procedure during operation. The measuring system automatically determines the actual drive offset by exciting the pipe in a reference state (without flowing medium or with stationary medium) and calculating the deviation from the nominal alignment. This preliminary measurement allows the system to compensate for manufacturing imperfections without requiring extremely tight manufacturing tolerances.
Solution Approach 2:
The patent utilizes parameter changes by measuring the drive offset as a variable parameter that can be determined and compensated. Instead of treating the alignment as a fixed manufacturing specification, the system dynamically determines the actual drive offset parameter during operation and uses it to correct measurement values, thereby decoupling measurement accuracy from manufacturing precision requirements.
2Measurement precision
If drive offset is minimized through precise alignment, then phase angle errors are reduced, but device complexity increases due to additional alignment and calibration requirements
Solution Approach 1:
The patent applies self-service by implementing an automatic self-alignment procedure. The measuring system performs its own calibration by exciting the pipe in a reference state, measuring the vibration response, and automatically calculating the drive offset. This eliminates the need for manual alignment procedures and external calibration equipment, thereby reducing device complexity despite the additional measurement capabilities required.
Solution Approach 2:
The patent utilizes feedback by continuously monitoring the vibration response of the pipe and comparing it with expected behavior. The system measures the actual drive offset and uses this feedback information to correct phase angle errors in real-time measurements. This closed-loop approach automatically compensates for alignment errors without requiring complex manual adjustment mechanisms.
3Reliability
If multiple vibration modes are utilized for measurement, then robustness against fluctuating material properties is improved, but difficulty of detecting and measuring increases
Solution Approach 1:
The patent applies partial action by selectively utilizing specific vibration modes (primarily the fundamental bending mode and selected higher modes) rather than attempting to measure all possible vibration modes. The system excites the pipe and measures the response in these selected modes, which provides sufficient robustness against material property variations without requiring complex analysis of the complete vibration spectrum.
Solution Approach 2:
The patent utilizes parameter changes by measuring vibration responses at different excitation frequencies corresponding to different natural modes of the pipe. By exciting the pipe at frequencies that correspond to its natural vibration modes and measuring the amplitude and phase responses, the system can determine flow parameters while being robust to material property variations. The different vibration modes provide complementary information that enhances measurement reliability.
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
Enhances measurement accuracy and robustness by minimizing drive offset effects and phase angle errors, allowing for precise determination of flow parameters even with fluctuating material properties, while maintaining a simplified calibration process.
Implementation Method 1
an excitation arrangement for converting electrical power into mechanical power useful for exciting and maintaining forced mechanical vibrations of the pipe arrangement
Implementation Method 2
a sensor arrangement for detecting mechanical vibrations of the pipe arrangement and for providing vibration signals representing vibrational movements of the pipe arrangement
Implementation Method 3
the pipe arrangement has at least one pipe (111), in which useful vibrations according to a vibration mode can be excited by the vibration exciter, each vibration mode having an associated resonance frequency and modal damping
Implementation Method 4
each vibration mode having an associated resonance frequency and modal damping
Data Source
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AI summary
The measuring system comprises a vibration-type transducer (10) and measuring system electronics (20) electrically coupled to the transducer (10) for controlling the transducer and for evaluating vibration measurement signals (s1, s2) provided by the transducer. The exciter assembly comprises a vibration exciter (31) which is designed to convert electrical power with an electrical current that changes over time into mechanical power, in such a way that, at a drive point, formed by the vibration exciter on the tube that is mechanically connected to the vibration exciter, a drive force that changes over time acts on the tube, wherein the vibration exciter (31) is positioned and designed such that a drive offset (ΔE), namely a smallest distance between a drive cross-sectional area of the tube surrounded by a notional circumferential line of the tube intersecting the drive point and a predefined reference cross-sectional area of the tube, is no more than 3°mm and/or less than 0.5% of the tube length, and wherein a vibration node of vibration movements formed between two vibration antinodes of said vibration movements of the at least one tube in a vibration mode of a second or higher order (deviating from a vibration mode of a first order) lies within the reference cross-sectional area. The measuring system electronics (20) is designed to feed electrical power into the vibration exciter (31) by means of an electrical drive signal (e1), having an electrical current that changes over time, in such a way that the tube performs forced mechanical vibrations with one or more vibration frequencies specified by the drive signal (e1), wherein the measuring system electronics both provides the drive signal (e1) with sinusoidal (useful) current components (eN1, eN2) having an (alternating current) frequency (feN1) or an (alternating current) frequency (feN2), in such a way that the (alternating current) frequency (feN1) deviates from a resonant frequency (f2n+1) of a vibration mode of an odd-numbered order naturally intrinsic to the tube and the (alternating current) frequency (feN2) deviates from a resonant frequency (f2n+2) of a vibration mode of an even-numbered order naturally intrinsic to the tube by less than 1% and/or by less than 1 Hz, and also determines measurement values for at least one flow parameter of a measuring material guided in the transducer based on corresponding useful signal components (s1N1; s2N1; s1N2; s2N2) of at least one of the vibration measurement signals (s1, s2).