Vortex Flow Meter Wall Flow Detection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Vortex flow measuring devices face measurement errors when dealing with two-phase media, particularly when the second phase flows as a wall flow in pipelines, due to interference from vibrations and inability to reliably detect the presence and proportion of the second phase.
Innovation Solution
A method using a bluff body and an eddy sensor with a turbulence measuring device to generate Kármán vortices, detect periodic pressure fluctuations, and select a narrow frequency band to identify the presence of a second phase based on kurtosis analysis, allowing for online detection of a wall flow without additional devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a vortex flow meter is used to measure two-phase media, then the flow velocity of the first phase can be determined from vortex frequency, but measurement errors occur due to the presence of the second phase flowing as wall flow
Solution Approach 1:
The patent segments the measurement task into two independent parts: (1) measuring the first phase flow using vortex frequency, and (2) detecting the second phase presence using kurtosis analysis of the same signal. This segmentation allows each measurement to be optimized independently, resolving the contradiction by enabling accurate first phase measurement while simultaneously detecting second phase interference.
Solution Approach 2:
The patent changes the analysis parameter from standard statistical measures to kurtosis, which specifically detects deviations from Gaussian distribution caused by second phase wall flow. This parameter change enables reliable second phase detection without affecting the vortex frequency-based first phase measurement, thus resolving the measurement reliability issue.
2Reliability
If additional devices are added to detect the second phase, then detection reliability improves, but device complexity and costs increase
Solution Approach 1:
The patent makes the vortex sensor multi-functional by enabling it to perform both first phase flow measurement (via vortex frequency) and second phase detection (via kurtosis analysis) using the same hardware. This universality eliminates the need for additional detection devices, resolving the contradiction between detection reliability and device complexity.
Solution Approach 2:
The measurement signal serves dual purposes: it provides information about first phase flow velocity and simultaneously contains characteristics that reveal second phase presence. The system essentially detects the second phase using its own measurement signal, without requiring external detection equipment, thus reducing complexity while maintaining reliability.
3Measurement precision
If the measurement signal is filtered to a narrow frequency band, then the useful signal component is isolated, but signal processing complexity increases
Solution Approach 1:
The patent extracts the useful signal component by filtering to a narrow frequency band around the vortex frequency, separating it from noise and other interference. This extraction enables precise vortex frequency detection while the subsequent kurtosis analysis of the filtered signal provides second phase detection, managing complexity through selective frequency domain analysis.
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 and timely detection of a wall flow of the second phase, integrating its measurement signal with the first phase's characteristics, reducing costs and complexity, and providing a direct measurement of the second phase's presence and mass fraction.
Implementation Method 1
Generating Kármán vortices in the flowing medium, at least in the region of the vortex sensor, by means of the baffle, wherein the vortices are detached from the baffle at a vortex shedding frequency dependent on an instantaneous flow velocity of the flowing medium
Implementation Method 2
Detecting periodic pressure fluctuations caused by the Kármán vortices in the flowing medium by means of the vortex sensor to generate a sensor signal corresponding to the pressure fluctuations
Implementation Method 3
Selecting a useful signal component from the sensor signal, which is, in particular, a narrow frequency band containing the vortex shedding frequency
Implementation Method 4
detecting the presence of the second phase of the flowing medium using the useful signal component selected from the sensor signal, in particular based on a kurtosis of the useful signal component
Data Source
Figure 1~2
Figure 3
Figure 4
AI summary
The invention relates to a method for monitoring and/or measuring an at least temporarily biphasic medium which flows in a pipe and has an especially gaseous first phase having a first density and an especially liquid second phase having a second density that differs from the first density. Said method uses a vortex flow meter (2) comprising at least one measuring tube (4) that is inserted into the pipe, a baffle element (8), and a vortex sensor (14). The vortex sensor (14) includes a sensitive section (16) that reacts to pressure variations and is arranged so as to at least partially border the wall of the measuring tube (4). In the disclosed method, the vortex flow meter (2) detects a wall flow of a second phase of a biphasic or multiphase medium when the vortex sensor (14) records a measurement signal containing characteristics of an interaction between a wall flow of the second phase of a flowing medium, said second phase flowing along a wall of the measuring tube (4), and the sensitive section (16) of the first vortex sensor (14).