Coriolis Flowmeter Density Comparison for Asymmetric Filling
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Solution Overview
Problem
Coriolis mass flowmeters with bent measuring tubes can incorrectly indicate flow due to asymmetric filling, leading to measurement errors, and existing solutions require frequent maintenance or additional costly sensors.
Innovation Solution
A method using a Coriolis mass flowmeter with two oscillators and bent measuring tubes, where the low points are arranged relative to the gravitational field, registering pressure differences and density variations to distinguish between standing and flowing media by comparing oscillation frequencies and damping characteristics, and setting a density difference limit value to determine flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a throttled bypass-capillary line is connected between the two pressure measuring points to equalize pressure, then pressure equalization is achieved, but maintenance effort increases due to frequent plugging
Solution Approach 1:
The patent extracts the problematic capillary line from the system and replaces it with a computational approach. Instead of using a physical bypass line that requires maintenance, the invention calculates the hydrostatic pressure component separately using density measurements and subtracts it from the total pressure difference, thereby eliminating the need for the capillary line and its associated maintenance issues.
Solution Approach 2:
The patent replaces the mechanical pressure equalization system (capillary line) with a computational method. By measuring density with the Coriolis flowmeter and calculating the hydrostatic pressure component, the system substitutes physical pressure equalization with mathematical correction, eliminating mechanical wear and plugging problems.
2Reliability
If a media property sensor is added to compare density or velocity of sound before and behind the flowmeter, then reliable distinction between standing and flowing medium is achieved, but device complexity and cost increase
Solution Approach 1:
The patent makes the Coriolis flowmeter multi-functional by utilizing its existing density measurement capability for an additional purpose. The density data, already collected for mass flow measurement, is repurposed to calculate hydrostatic pressure and distinguish between flowing and standing media, eliminating the need for separate density sensors while expanding the flowmeter's functionality.
Solution Approach 2:
The patent enables the Coriolis flowmeter to serve itself by using its own density measurement data to correct pressure difference measurements. The system performs self-diagnosis and self-correction by comparing calculated hydrostatic pressure with actual pressure difference, thereby distinguishing flow conditions without external sensors.
3Measurement precision
If the Coriolis mass flowmeter is used as differential pressure producer, then flow measurement capability is improved, but measurement errors occur due to asymmetric liquid column filling
Solution Approach 1:
The patent implements a feedback mechanism where the system continuously monitors density measurements and calculated hydrostatic pressure to detect asymmetric filling conditions. When asymmetry is detected, the system adjusts or flags the pressure difference measurement accordingly, providing feedback-based error correction that maintains measurement reliability while preserving the dual-function capability of the flowmeter.
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 method provides a reliable and low-maintenance way to differentiate between standing and flowing media, reducing measurement errors and costs by accurately interpreting pressure differences and density fluctuations.
Implementation Method 1
the bent measuring tubes have, in each case, a low point, which is arranged relative to a local gravitational field at the deepest point of the measuring tube
Implementation Method 2
registering a first density measured value based on at least a first oscillation frequency of the first oscillator; registering a second density measured value based on at least a second oscillation frequency of the second oscillator
Implementation Method 3
a pressure difference measuring device, which is adapted to ascertain a pressure difference between a first pressure measuring point and a second pressure measuring point of a pipeline
Implementation Method 4
Coriolis mass flowmeter with bent measuring tubes
Implementation Method 5
damping characteristics
Data Source
AI summary
A method for monitoring flow of a medium by means of a pressure difference measuring device and a Coriolis mass flowmeter having two oscillators, which comprise, in each case, a bent measuring tube pair, which are arranged on top of one another and connected for parallel flow between the two pressure measuring points of the pressure difference measuring device, comprising steps as follows: Registering a pressure difference between the first pressure measuring point and the second pressure measuring point; registering a first density measured value based on at least a first oscillation frequency of the first oscillator; registering a second density measured value based on at least a second oscillation frequency of the second oscillator; ascertaining a flow measured value based on the pressure difference, when a difference between the first density measured value and the second density measured value is less than a density difference limit value.