Vortex air flow sensor

Vortex air flow sensor

Overview of Vortex air flow sensor

Vortex flow meter is a kind of velocity flow meter made according to the Karman vortex theory, using the principle of natural vibration of the fluid, and using piezoelectric crystal or differential capacitor as the detection component.

Features of Vortex air flow sensor

The flow sensor has many remarkable advantages, such as no movable parts, large measurement range, wide medium adaptability, high measurement accuracy, long verification cycle, long transmission signal distance, small pressure loss, simple structure, reliable operation, long service life, convenient installation and maintenance, etc. It can be widely used in the process measurement and energy-saving management of various single-phase fluids such as liquids, gases and vapors in petrochemical, metallurgical machinery, food, papermaking, urban pipeline heating, water supply, gas and other industries.

Working principle of Vortex air flow sensor

Selection of pressure compensation pressure transmitter: due to the long saturated steam pipeline and large pressure fluctuation, pressure compensation must be adopted. Considering the corresponding relationship between pressure, temperature and density, only pressure compensation can be adopted in the measurement. Since the saturated steam pressure of Mingtong company's pipeline is in the range of 0.3-0.7mpa, the range of pressure transmitter can be selected as 1MPa.

Pressure compensation
1. When the measured medium contains more impurities, a filter should be installed outside the required length of the straight pipe upstream of the sensor. 2. The sensor shall not be installed on the pipeline with mechanical vibration. When vibration is unavoidable, it should be considered to add a fixed support frame on the straight pipe section about 2DN away from the front and back of the sensor. 3. The sensor should not be installed in places with strong electromagnetic interference, thermal radiation, corrosive gas, small space and inconvenient maintenance.

Vortex flow sensors are widely used in petroleum, chemical, metallurgical and other industrial departments, as well as in municipal engineering and environmental protection industries, and steam flow measurement, detection and control.
Vortex flow sensor is a new type of flowmeter based on Carmen vortex principle to measure the fluid flow in closed pipelines. Because of its good medium adaptability, it can directly measure the working condition volume flow of steam, air, gas, water and liquid without temperature and pressure compensation. Equipped with temperature and pressure sensors, it can measure the standard condition volume flow and mass flow. It is an ideal substitute for throttling flowmeter.

Basic structure of Vortex air flow sensor
(1) The experimental pipeline, the device is composed of 8 standard sensors with a diameter of DN = 50~150mm in series, and the parallel combination is compared with the large diameter sensor (DN = 80~300mm) to be detected. The test pipelines are arranged in parallel in the diagonal direction, the purpose is to save raw materials, reduce the cost, and just meet the requirements of the front straight section of various caliber sensors (according to the national standard ZBN12005-1989 or regulations JJG643-1994) Standard sensor front straight The length of the pipe section is greater than 50DN; the length of the straight pipe section before the detected sensor is greater than 20DN; the resistance loss is reduced to the minimum value.
(2) Air source, the air source is supplied by two 9-19 type high pressure centrifugal fans and one LG300×200-1 type Roots fan. Among them, two centrifuges of the same type can be operated in series or in parallel by controlling the electric valve according to the needs of the flow rate, so as to meet the requirements of different flow rates and different pressures.
(3) Standard sensor: The device uses 8 standard sensors, all of which are stress-type vortex sensors. The advantage of this instrument is that it has no moving parts, has high repeatability, and has strong overload and impact resistance. The stainless steel for the sensor body is resistant to wear and corrosion, and the sensor has high stability. In addition, the instrument coefficient of this type of sensor is not or is rarely affected by the physical parameters of the measured medium, so when used as a standard sensor, as long as it is basically consistent with the measured material.
At present, the standard degree of gas vortex sensor in my country is generally at the level of 0.5 to 1. From the level of accuracy, it cannot be used as a 0.5 standard sensor, but the range of such instruments is very wide. Generally, it is about 10:1~15:1, and the repeatability is very good, all within 0.2%, or even higher. For example, using the compression range to calibrate at a fixed point is an effective method to improve the accuracy. We have done a lot of experimental research work, and the results show that if the range is compressed to within 2:1 or 3:1, the fixed-point calibration can meet the requirements. Therefore, it is feasible to use this sensor standard to establish a gas flow device.