Tertiary Mode Coriolis Flowmeter Vibration Leakage
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Solution Overview
Problem
Conventional Coriolis flowmeters with single flow paths experience vibration leakage and zero-point drift due to changes in piping conditions, leading to instrumental errors, especially when using bending vibration modes without counter balancers.
Innovation Solution
A tertiary mode vibration type Coriolis flowmeter with a flow tube in a T-shaped configuration, where the flow tube is driven by bending vibration, and the fixed ends of the leg parts are arranged close together in the same plane, satisfying specific geometric conditions to convert bending vibration into twisting vibration, thereby canceling leakage and reducing rigidity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single flow path is used without branching, then clogging is prevented and flow stability is improved, but vibration leakage occurs and zero-point drift increases
Solution Approach 1:
The flow tube is segmented into multiple vibration modes (tertiary mode and higher modes) with different vibration directions. The tertiary mode vibrates in one direction while higher modes vibrate in orthogonal directions, allowing the harmful vibration leakage to be directed away from the measurement axis while maintaining flow stability through the single path configuration.
2Device complexity
If bending vibration is applied to a single tube, then the structure is simple, but the influences of density and temperature on vibration leakage are inevitable
Solution Approach 1:
The flow tube is driven to vibrate in tertiary mode bending vibration, which naturally generates higher mode vibrations in orthogonal directions. This mechanical vibration approach eliminates the need for complex counter-balancer systems while the orthogonal vibration components cancel out density and temperature influences on vibration leakage, improving instrumental error property.
3Measurement precision
If the flow tube is vibrated in tertiary mode, then detection sensitivity is improved, but vibration leakage to the exterior occurs
Solution Approach 1:
Different sections of the flow tube are assigned different vibration characteristics. The measurement section utilizes tertiary mode vibration for high detection sensitivity, while other sections generate higher mode vibrations in orthogonal directions that cancel out vibration leakage to the exterior, allowing local optimization of both sensitivity and leakage reduction.
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 configuration stabilizes vibration with minimal energy consumption, reduces zero-point drift and span fluctuation, and enhances Coriolis force detection sensitivity by minimizing vibration leakage and maintaining instrumental accuracy across varying conditions.
Implementation Method 1
The Coriolis flowmeter is a mass flowmeter, which utilizes the fact that the Coriolis forces applied to the flow tube when vibration is thus applied thereto, are proportional to a mass flow rate
Implementation Method 2
The drive device drives the flow tube by bending vibration in a tertiary mode
Data Source
AI summary
A tertiary mode vibration type Coriolis flowmeter includes a flow tube, a drive device driving the flow tube, and a pair of vibration detecting sensors detecting a phase difference in proportion to a Colioris force acting on the flow tube. The drive device drives the flow tube by bending vibration in a tertiary mode. The flow tube further comprises an approximately loop-shaped body part. A pair of parallel leg parts deflected in a direction approximately orthogonal to the vibrating direction of both end parts of the body part, namely, to the outside of the both end parts are formed continuously with the both end parts of the body part. Fixed end parts supporting the flow tube are formed at the leg parts.