Principle of plug-in vortex flowmeter

Principle of plug-in vortex flowmeter

Mainly used for flow measurement of industrial pipeline media fluids, such as gases, liquids, vapors, and other media. Its characteristics are small pressure loss, large range, high accuracy, and almost unaffected by parameters such as fluid density, pressure, temperature, viscosity, etc. when measuring volumetric flow rate under working conditions. No movable mechanical parts, therefore high reliability and low maintenance. The instrument parameters can remain stable for a long time. Using piezoelectric stress sensors, it has high reliability and can operate within a temperature range of -20 ℃ to 250 ℃. It has both analog standard signals and digital pulse signal outputs, making it easy to use in conjunction with digital systems such as computers. It is a relatively advanced and ideal flow meter.

Secondly:Principle of plug-in vortex flowmeter

The vortex flowmeter is equipped with a triangular cylindrical vortex generator in the fluid, which alternately generates regular vortices from both sides of the vortex generator. This type of vortex is called a Karman vortex, as shown in the figure on the right. The vortex columns are asymmetrically arranged downstream of the vortex generator.
Assuming the frequency of vortex occurrence is f, the average flow velocity of the measured medium is, the width of the upstream surface of the vortex generator is d, and the diameter of the body is D, the following relationship can be obtained:
F=SrU1/d=SrU/md, where U1 represents the average velocity on both sides of the vortex generator, m/s；
Sr Strouhal number;
M - The ratio of the bow shaped area on both sides of the vortex generator to the cross-sectional area of the pipeline

It is a new type of flowmeter for measuring fluid flow in closed pipelines based on the Karman vortex principle. Due to its excellent medium adaptability, it can directly measure the volumetric flow rate of steam, air, gas, water, and liquid without temperature and pressure compensation. Equipped with temperature and pressure sensors, it can measure standard volumetric flow rate and mass flow rate, making it an ideal alternative to throttling flow meters.
To improve high temperature resistance and vibration resistance, our company has recently developed the KY LU improved vortex flow sensor. Due to its structure and material selection, the sensor can be used in harsh working conditions such as high temperature (350 ℃) and strong vibration (≤ 1g).
In practical applications, large flow rates are often much lower than the upper limit value of the instrument, and with changes in load, small flow rates often fall below the lower limit value of the instrument. The instrument is not working in its optimal operating range. To solve this problem, it is usually necessary to reduce the diameter at the measuring point to increase the flow rate at the measuring point, and use smaller diameter instruments to facilitate the measurement of the instrument. However, this variable diameter method requires a straight pipe section with a length of 15D or more between the variable diameter pipe and the instrument for rectification, which makes processing and installation inconvenient. Our company has developed an LGZ variable diameter rectifier with a curved longitudinal section, which has multiple functions of rectification, increasing flow velocity, and changing flow velocity distribution. Its structural dimensions are small, only one-third of the inner diameter of the process tubevortex flow meterAs a whole, it not only does not require an additional straight pipe section, but also reduces the requirements for the straight pipe section of the process pipe, making installation very convenient.
For ease of use, battery powered local display typevortex flow meterAdopting low-power consumption and lithium battery power supply, it can operate continuously for more than a year, saving the procurement and installation costs of cables and display instruments. It can display instantaneous flow, cumulative flow, etc. on site. Temperature compensation

Three:Plug in vortex flowmeterParameters and requirements

Measurement medium: gas, liquid, vapor
◆ Caliber specifications: Flange card mounted caliber selection: 25, 32, 50, 80, 100
◆ Flange connection type with a diameter selection of 100, 150, 200
◆ Flow measurement range Normal measurement flow velocity range Reynolds number 1.5 × 104~4 × 106; Gas velocity of 5-50m/s; Liquid 0.5-7m/s
The normal measurement range for liquid and gas flow is shown in Table 2; The steam flow range is shown in Table 3
Measurement accuracy level 1.0 and 1.5
◆ Temperature of the tested medium: normal temperature -25 ℃~100 ℃
◆ High temperature -25 ℃~150 ℃ -25 ℃~250 ℃
Output signal pulse voltage output signal high level 8-10V low level 0.7-1.3V
The pulse duty cycle is about 50%, and the transmission distance is 100m
Pulse current remote transmission signal 4-20 mA, transmission distance of 1000m
◆ Instrument operating environment temperature: -25 ℃~55 ℃ humidity: 5-90% RH50 ℃
◆ Material: Stainless steel, aluminum alloy
◆ Power supply DC24V or lithium battery 3.6V
Explosion proof grade intrinsic safety type iaIIbT3-T6
Protection level IP65

Four:vortex flow meterSelection Table

Five:vortex flow meterInstallation requirements

Installation requirements

1. The sensor should be installed on a pipeline with the same diameter as the horizontal, vertical, and inclined (liquid flow from bottom to top) pipeline. The upstream and downstream of the sensor should be equipped with a certain length of straight pipe section, which should meet the requirements of 15-20D for the front straight pipe section and 5-1OD for the rear straight pipe section.

2. The pipeline near the installation of the liquid sensor should be filled with the measured liquid.

3. Sensors should be avoided from being installed on pipelines with strong mechanical vibrations.

4. The inner diameter of the straight pipe section should be as close as possible to the sensor diameter *. If * is not possible, a pipe slightly larger than the sensor diameter should be used, with an error of ≤ 3% and not exceeding 5mm.

5. When the measured medium contains a large amount of impurities, a filter should be installed beyond the required length of the straight pipe section upstream of the sensor.

Sensors should be avoided from being installed in places with strong electromagnetic field interference, small space, and inconvenient maintenance.

The installation of vortex flowmeter requires a certain amount of front and rear straight pipe sections, and common situations are as follows (DFor the diameter of the pipeline: