In-line Coriolis Flow Meter Eigenmode Coupling Error Compensation
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Solution Overview
Problem
Coriolis mass flow measuring devices face significant accuracy issues when measuring two-phase or multi-phase media due to fluctuations in oscillation measurement signals, leading to substantial measurement errors, which conventional correction methods, such as the 'bubble theory', cannot fully address, especially in cases of positive errors and varying conditions.
Innovation Solution
The method involves tracking the drift of eigenmode coupling between the vibrating tube and the mixture components, using an analytical model to determine appropriate coupling coefficients, and accounting for the dynamical characteristics of the mixture volume to predict and correct errors, allowing for accurate measurement of mass flow and density even in inhomogeneous media.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional correction methods (e.g., bubble theory) are used to measure two-phase or multi-phase media, then measurement capability is extended to inhomogeneous media, but measurement precision deteriorates due to substantial measurement errors that cannot be fully corrected
Solution Approach 1:
The patent changes the measurement parameters by using multiple oscillation modes (first and second natural eigenmodes) instead of a single mode. By measuring coupling coefficients between different modes and using frequency ratios, the system obtains multiple independent parameters that enable accurate measurement of both density and mass flow rate even in two-phase media, resolving the precision issue while maintaining versatility
Solution Approach 2:
The patent adds a dimensional aspect by introducing mode coupling coefficients as an additional measurement dimension. Instead of relying solely on single-mode oscillation parameters, the system measures the coupling between different oscillation modes, providing extra independent information that enables accurate correction of measurement errors in inhomogeneous media
2Device complexity
If single-mode oscillation is used in vibratory transducers, then device complexity is kept simple, but measurement precision deteriorates due to inability to account for mixture dynamics
Solution Approach 1:
The patent introduces mode coupling coefficients as an additional measurement dimension without fundamentally changing the transducer structure. By measuring the coupling between existing oscillation modes rather than adding new hardware, the system achieves improved precision while maintaining relatively simple device complexity
Solution Approach 2:
The patent makes the existing oscillation modes serve multiple functions by measuring both the primary measurement parameters and the mode coupling coefficients from the same oscillation system. This multi-functionality approach enables accurate measurement in both single-phase and two-phase media without requiring separate measurement systems
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 provides accurate mass flow and density measurements with an error of less than 10% in two-phase or multi-phase mixtures, effectively addressing the limitations of conventional methods by decoupling density and mass flow errors and simplifying correction value determination, with reproducible results across a wide range of applications.
Implementation Method 1
feeding an excitation current into an exciter arrangement mechanically coupled with the measuring tube conducting the mixture, for causing the measuring tube to execute mechanical oscillations
Implementation Method 2
inducing Coriolis forces within the mixture flowing through said vibrating measurement tube
Implementation Method 3
sensing vibrations of the measuring tube and producing at least one oscillation measurement signal representing oscillations of the vibrating measuring tube
Implementation Method 4
tracking the drift of eigenmode coupling between the vibrating tube and the mixture components, using an analytical model to determine appropriate coupling coefficients
Data Source
AI summary
An inline measuring device comprises a vibratory-type transducer and a measuring device electronics electrically coupled with the vibratory-type transducer. The vibratory-type transducer includes at least one measuring tube being inserted into the course of a pipeline and serving for conducting a mixture to be measured. An exciter arrangement acting on the measuring tube for causing the at least one measuring tube to vibrate and a sensor arrangement sensing vibrations of the at least one measuring tube and delivering at least one oscillation measurement signal representing oscillations of the measuring tube. The measuring device electronics delivers an excitation current driving the exciter arrangement. Further, the inline measuring device electronics is adapted to produce a measured value representing the physical, measured quantity of the mixture to be measured. Therefor, the measuring device electronics estimates from the excitation current and from said at least one oscillation measurement signal a Coriolis coupling coefficient. This Coriolis coupling coefficient corresponds with an instantaneous coupling between a first natural eigenmode of the measuring tube currently driven by the exciter arrangement and a second natural eigenmode of said measurement tube. In this second eigenmode the measurement tube has an eigenform corresponding with a mode of vibration caused by Coriolis forces induced in the flowing mixture. Due to a variation of a concentration of at least one of a component of the mixture the Coriolis coupling coefficient varies in time.