Vibrating Flow Meter Velocity of Sound Error Correction
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Solution Overview
Problem
Vibrating flow meters face errors due to compressibility, particularly when the velocity of sound in the process fluid is unknown, leading to inaccuracies in density and mass flow rate measurements, especially in high-frequency operations and for gaseous mixtures with unknown compositions.
Innovation Solution
A method and apparatus that calculate the velocity of sound using measurements from a vibrating flow meter by generating multiple density measurements at different frequencies, allowing for error correction and determination of actual density and mass flow rate without external acoustic sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the tube oscillation frequency is increased to improve measurement speed and responsiveness, then productivity is improved, but measurement precision deteriorates due to increased compressibility errors
Solution Approach 1:
The patent replaces the traditional mechanical correction approach with a signal processing solution. By using digital signal processing to separate the velocity of sound effect from the density measurement signal, the system can operate at high frequencies without suffering from compressibility errors. The pick-off sensor signals are processed to extract the actual density information while eliminating the velocity of sound interference, thus maintaining measurement precision at high oscillation frequencies.
2Measurement precision
If additional acoustic sensors are added to measure velocity of sound for error correction, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent makes the existing pick-off sensors perform multiple functions. These sensors originally designed for measuring tube vibration are also used to extract velocity of sound information through signal processing. By analyzing the phase and amplitude relationships in the pick-off signals at different frequencies, the system determines velocity of sound without requiring dedicated acoustic sensors, thus maintaining measurement precision while avoiding increased device complexity.
Solution Approach 2:
The system uses its own existing components and signals to achieve velocity of sound measurement. The pick-off sensors and their output signals, which are already present in the Coriolis flow meter system, are utilized to extract velocity of sound information through appropriate signal processing algorithms, eliminating the need for external or additional measurement devices.
3Measurement precision
If velocity of sound effects are corrected using known models, then measurement precision is improved, but adaptability decreases when fluid composition is unknown
Solution Approach 1:
The patent changes the approach from using fixed fluid property parameters to dynamically determining velocity of sound as a measurable parameter. Instead of relying on known fluid composition data or lookup tables, the system measures velocity of sound directly from the pick-off sensor signals by analyzing the relationship between tube vibration frequency and the measured density. This measured velocity of sound is then used for real-time error correction, making the system adaptable to any fluid composition without requiring prior knowledge.
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 accurate determination of fluid properties like velocity of sound, density, and mass flow rate by comparing calculated and expected values, reducing errors caused by compressibility and eliminating the need for additional sensors, thus improving measurement reliability and accuracy.
Implementation Method 1
vibrating the flow meter at one or more frequencies; receiving a vibrational response
Implementation Method 2
One potential source for error in vibrating flow meters is caused by compressibility, also known as velocity of sound effects
Implementation Method 3
Vibrating conduit sensors, such as Coriolis mass flow meters and vibrating densitometers typically operate by detecting motion of a vibrating conduit that contains a flowing material
Data Source
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AI summary
A method for calculating a fluid parameter of a fluid flowing through a vibratory flow meter is provided. The method comprises vibrating the flow meter at one or more frequencies and receiving a vibrational response. The method further comprises generating a first fluid property and generating at least a second fluid property. The method further comprises calculating a fluid parameter based on the first fluid property and the at least second fluid property.