Coriolis Mass Flowmeter Mode Comparison for Zero-Point Detection
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Solution Overview
Problem
Existing Coriolis mass flowmeters struggle to detect changes in zero-point errors during ongoing operations due to asymmetries in the vibration behavior of the measuring tube, which are not easily identifiable using current monitoring methods, leading to undetected measurement errors in mass flow rate determination.
Innovation Solution
A method that excites two symmetrical bending vibration modes in the measuring tube, determines mass flow rate measurements based on Coriolis deformations, calculates a zero-point deviation value from the difference between these measurements, and signals an error if the deviation exceeds a threshold, while accounting for influences such as gas loading and local damping.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a single symmetrical bending vibration mode is used for mass flow rate measurement, then the measurement process is simple, but zero-point errors due to asymmetries in vibration behavior cannot be detected during ongoing operations
Solution Approach 1:
The measurement process is segmented into multiple independent vibration modes (first and second symmetrical bending vibration modes), each providing separate mass flow rate measurements. This segmentation allows comparison between modes to detect zero-point deviations without complicating the individual measurement processes.
Solution Approach 2:
The system changes the vibration mode parameter by exciting different symmetrical bending vibration modes of the measuring tube. Each mode provides a different measurement perspective, and comparing results across modes enables detection of zero-point errors while maintaining operational simplicity.
2Reliability
If multiple symmetrical bending vibration modes are excited and compared, then zero-point deviations can be detected, but the device complexity and measurement process increase
Solution Approach 1:
The measuring tube serves multiple functions by supporting excitation of different symmetrical bending vibration modes. This multi-functionality allows zero-point error detection without requiring additional sensing elements or complex hardware, as the same tube provides multiple measurement perspectives.
Solution Approach 2:
The system uses its own vibration characteristics across different modes to self-diagnose zero-point errors. The comparison between measurements from different vibration modes enables the system to automatically detect deviations without external intervention or additional monitoring equipment.
3Device complexity
If zero-point errors are not monitored during operation, then the measurement system remains simple, but undetected measurement errors occur in mass flow rate determination
Solution Approach 1:
The system implements feedback by comparing mass flow rate measurements from different vibration modes and using the deviation as an indicator of zero-point errors. This feedback mechanism maintains measurement precision without requiring complex external monitoring systems, as the comparison itself provides the error detection capability.
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
Enables timely detection of changing zero-point errors by comparing mass flow rate measurements across different vibration modes, reducing undetected measurement errors and ensuring accurate flow rate calculations.
Implementation Method 1
The first Coriolis deformation results from the inertial forces of the flowing medium in response to the vibration of the measuring tube in the first symmetric bending mode. The second Coriolis deformation results from the inertial forces of the flowing medium in response to the vibration of the measuring tube in the second symmetric bending mode.
Implementation Method 2
Exciting a first symmetrical bending vibration mode of the at least one measuring tube; exciting a second symmetrical bending vibration mode of the at least one measuring tube
Data Source
Figure 1a~1b
Figure 2a~3c
Figure 4a~4c
AI summary
The invention relates to a method (100) for operating a Coriolis mass flowmeter having at least one vibratable measuring tube for guiding a medium, the method comprising: exciting (110a) a first symmetrical bending vibration mode of the at least one measuring tube; exciting (110b) a second symmetrical bending vibration mode of the at least one measuring tube; determining (120a) a first mass flow rate measurement value on the basis of a first Coriolis deformation of the at least one measuring tube and a first stored mode-specific zero point error value; determining (120b) a second mass flow rate measurement value on the basis of a second Coriolis deformation of the at least one measuring tube and a second stored mode-specific zero point error value; and determining (130) a zero point deviation value of the mass flow rate measurement as a function of a deviation between the first mass flow rate measurement value and the second mass flow rate measurement value.