Straight-Tube Coriolis Flowmeter Using CFRTP for Corrosive Fluids
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Solution Overview
Problem
Conventional Coriolis mass flowmeters face challenges in measuring corrosive fluids without metal ion elution, maintaining precision under temperature variations, and achieving high sensitivity for small flow rates while minimizing pressure loss and external vibration noise.
Innovation Solution
A Coriolis mass flowmeter using a straight tube made of carbon fiber reinforced thermoplastic (CFRTP) with balanced vibration detector and exciter masses, supported by frames, to minimize torsional spring constant and maximize detector sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a metal tube is used to maintain stable modulus of elasticity under varying temperatures, then measurement stability is improved, but metal ion elution into corrosive fluids occurs
Solution Approach 1:
The patent employs a composite tube structure consisting of an inner fluororesin layer (preventing metal ion elution) and an outer metal layer (maintaining modulus of elasticity stability). This composite construction allows the tube to resist corrosive fluids while maintaining dimensional stability under temperature variations, thereby preventing metal ion contamination while ensuring measurement reliability.
Solution Approach 2:
The fluororesin coating acts as an intermediary barrier between the metal tube and the corrosive fluid. This intermediate layer prevents direct contact between the metal surface and the fluid, thereby eliminating metal ion elution while the metal substrate continues to provide thermal and mechanical stability for accurate measurements.
2Object-affected harmful factors
If fluororesin coating is applied to the tube to prevent metal ion elution, then corrosion resistance is improved, but coating application on bent parts becomes difficult and coating thickness cannot be increased
Solution Approach 1:
Instead of coating the bent tube surface (which is difficult), the patent inverts the approach by applying the fluororesin coating to the tube before bending, or using a coating method that can uniformly coat complex geometries. This allows the coating to be applied to the inner and outer surfaces of bent sections without the limitations of conventional post-bending coating methods.
3Measurement precision
If tube diameter is reduced to increase sensitivity for small flow rate measurement, then measurement sensitivity is improved, but pressure loss increases
Solution Approach 1:
The patent optimizes the tube diameter parameter to achieve the optimal balance between sensitivity and pressure loss. By carefully selecting and adjusting the tube diameter, the design maximizes the Coriolis effect for enhanced measurement sensitivity while minimizing flow resistance and pressure loss, thereby resolving the trade-off between these two critical parameters.
4Measurement precision
If tube wall thickness is reduced to decrease torsional spring constant for higher sensitivity, then measurement sensitivity is improved, but structural strength decreases
Solution Approach 1:
The composite structure with optimized wall thickness combines a thin fluororesin layer for corrosion resistance with a metal layer providing mechanical strength. This allows the tube to have sufficient structural integrity while maintaining low torsional spring constant for high measurement sensitivity.
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
The flowmeter provides stable measurements for corrosive fluids with high sensitivity and reduced noise interference, maintaining precision across temperature changes and small flow rates.
Implementation Method 1
a fluid flowing through a tube generates a rotary motion, the fluid receives a Coriolis force, which is proportional to the vector product of the velocity vector of the flow and the angular velocity vector of the rotation
Implementation Method 2
Coriolis mass flowmeters typically operate by vibrating a tube through which a fluid passes, and detecting the elastic deformation of the tube due to the effect of the Coriolis force of the fluid
Implementation Method 3
detecting the phase difference of vibration occurring between the upstream and downstream points of the flow path due to the mass flow rate of the fluid
Implementation Method 4
an elastic polymer material having two flow rate detection members... having excellent flexibility and creep resistance
Implementation Method 5
the tube, the supports and the frame are made of a plastic material with high elasticity... carbon fiber reinforced thermoplastic (CFRTP)
Data Source
AI summary
A Coriolis mass flowmeter whose targets of measurement include a corrosive fluid and which has no risk of elution of metal ions. The Coriolis mass flowmeter comprises a straight tube through which a fluid to be measured flows; a vibration exciter for exciting the tube to vibrate; a first vibration detector and a second vibration detector for detecting the vibration of the tube; and supports for supporting each end of the tube to serve as fixed ends for the vibration; wherein the vibration exciter, the first vibration detector and the second vibration detector are supported by frames connected to the supports; wherein a mass flow rate of the fluid flowing through the tube is determined based on a phase shift of vibration waveforms detected by the first vibration detector and the second vibration detector. The tube, the supports and the frames are made of a plastic material with high elasticity.