Coriolis Flowmeter Correction for Non-Ideal Ethylene Measurement
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Solution Overview
Problem
Conventional Coriolis flowmeters face challenges in accurately measuring critical phase ethylene due to its non-ideal gas properties, which result in significant density and velocity-of-sound changes with small temperature and pressure variations, leading to unacceptable measurement errors.
Innovation Solution
A method and system for a Coriolis flowmeter that calculates a corrected mass flow rate by measuring fluid temperature and density, using a velocity of sound correction to account for non-ideal gas behavior, employing a mass flow correction routine to adjust for errors based on temperature and density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional Coriolis flowmeters are used to measure critical phase ethylene, then the measurement system is simple and operates under normal conditions, but measurement precision deteriorates due to large density and velocity-of-sound changes with small temperature and pressure variations
Solution Approach 1:
The patent implements a feedback mechanism where the measured density and temperature are used to calculate the velocity of sound, which then corrects the mass flow rate measurement. The system continuously monitors density changes and adjusts the flow measurement accordingly, creating a closed-loop correction system that compensates for the non-ideal gas behavior of critical phase ethylene.
Solution Approach 2:
The patent performs preliminary calculations of the velocity of sound based on measured density and temperature before applying the correction to the mass flow rate. By pre-calculating the correction factor using the measured parameters, the system prepares the necessary correction data in advance, allowing for accurate real-time measurement without adding complex hardware.
2Measurement precision
If density and velocity-of-sound changes are accounted for in real-time, then measurement precision improves, but device complexity increases due to additional measurements and calculations
Solution Approach 1:
The system uses the Coriolis flowmeter's own density measurement capability to generate the correction data. The density measurement, already performed by the flowmeter, is reused to calculate the velocity of sound and apply the correction, eliminating the need for separate density measurement devices or external correction systems.
Solution Approach 2:
The patent makes the density measurement serve multiple functions: it is used both for the standard Coriolis mass flow calculation and for calculating the velocity of sound correction. This multi-functional use of the density data maximizes the value extracted from existing measurements without requiring additional sensors or measurement systems.
3Measurement precision
If velocity of sound correction is applied, then measurement precision improves for non-ideal fluids, but ease of operation deteriorates due to additional correction steps
Solution Approach 1:
The system automatically performs the velocity of sound correction without requiring manual intervention. The correction is calculated and applied automatically based on the measured density and temperature, making the process transparent to the operator and maintaining ease of operation while improving accuracy.
Solution Approach 2:
The correction calculations are performed automatically and continuously in the background, preparing the corrected mass flow rate data without requiring the operator to manually apply corrections. This preliminary automatic correction ensures that the displayed measurement is already accurate, eliminating the need for manual adjustment steps.
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 more accurate mass flow measurements for ethylene and similar fluids by minimizing errors associated with density and velocity-of-sound variations, ensuring reliable measurement within specified tolerances.
Implementation Method 1
A velocity of sound (VoS) of the fluid is calculated... A 1 psi pressure change causes a 5 m/s VoS change
Implementation Method 2
Vibrating conduit sensors, such as Coriolis mass flowmeters... detecting motion of a vibrating conduit that contains a flowing material
Implementation Method 3
Excitation is typically provided by a driver, e.g., an electromechanical device, such as a voice coil-type actuator, that perturbs the conduit in a periodic fashion
Data Source
AI summary
A method and apparatus for operating a flowmeter (5) is provided. A process fluid is placed in the flowmeter (5). A temperature of the fluid is measured. A density of the fluid is measured. A velocity of sound (VoS) of the fluid is calculated. A mass flow rate error is calculated, and a corrected mass flow rate of the fluid is calculated.