What is the general unit used to measure gas flow rate in vortex flow? What does it have to do with

Vortex flowmeter.

It is composed of several parts, such as vortex generator, vortex frequency detection element and signal processing circuit. The vortex flowmeter, also known as the Kármán vortex flowmeter, is a vortex separation flowmeter made of the principle of natural oscillation of fluids. When a fluid flows through a columnar object at a sufficiently large flow rate, behind the columnar object, a neatly arranged and reversed vortex column is created along two parallel straight lines, called "Kármán vortex street."

phenomenon". The vortex frequency is proportional to the average flow velocity of the fluid and the frontal width d of the generator, which has the following relationship:

f = stv/d

Where: f - vortex frequency, hz;

d - width of vortex generator, m;

v - the average flow velocity of the fluid, m s;

st – Strauhar number, dimensionless.

Its numerical range is: st is the Reynolds number.

, st=(f l re).

When the Reynolds number Re is in the range of 102-105, the ST value is about, therefore, in the measurement, try to satisfy the Reynolds number of the fluid in the range of 102-105, and the vortex frequency f.

It can be seen that the average velocity of the fluid flowing through the vortex generator can be calculated by measuring the vortex frequency.

v, and then the flow rate q can be obtained by the formula q=va, where a is the cross-sectional area of the fluid flowing through the vortex generator.

The vortex flowmeter can be used for the flow measurement technology of gas, steam and liquid with the same sensor body, with high accuracy, wide range ratio and high temperature resistance, especially in the application of steam metering.

The vortex flowmeter is mainly used for the flow measurement of industrial pipeline medium fluids, such as gas, liquid, vapor and other media. It is characterized by small pressure loss, large measuring range, high accuracy, and is almost not affected by fluid density, pressure, temperature, viscosity and other parameters when measuring the volume flow under working conditions. There are no moving mechanical parts, so it is highly reliable and requires little maintenance.

The instrument parameters can be stable for a long time. The vortex flowmeter uses a piezoelectric stress sensor for high reliability and can operate in the operating temperature range of -20 +250. There are analog standard signals, there are also digital pulse signal output, easy to use with computers and other digital systems, is a relatively advanced, ideal measuring instrument.

1.Turbine flow meters are used to measure the flow rate of liquids, gases, and vapors in pipelines, such as carbon oxides, chemicals, water, cryogenic liquid cherry blossoms, air, and industrial gases. High-precision turbine flowmeters can be used with ridges like socks for hydrocarbons.

and natural gas ** handover. These turbine flow meters typically incorporate the functionality of a flow computer to correct pressure, temperature, and fluid properties to achieve the accuracy required for the application.

2.Be careful when using turbine flow meters when there is no lubricated fluid, as if the flow meter wears out prematurely, the flow meter may become inaccurate and fail. Some turbine flow meters have grease fittings for non-lubricated fluids.

In addition, turbine flow meters designed for specific purposes (e.g., natural gas services) often operate within a limited temperature range (e.g., up to 60 C), so operating at higher temperatures may damage the flow meter.

3.This flow meter can be applied to hygienic, relatively clean and corrosive liquids up to about 24 inches in size. Smaller turbine flow meters can be installed directly in pipes, but the size and weight of larger turbine flow meters may require the installation of a large number of concrete foundations and supports.

Due attention is paid to the flow of corrosive liquids and to the materials of construction of all wetted parts such as valve bodies, rotors, bearings, and fittings.

4.Applications for turbine flow meters can be found in the water, petroleum, and chemical industries. Water applications include distribution systems within oak burial areas and between water bodies.

Petroleum applications include the transfer of hydrocarbons. Other applications can be found in the food and beverage and chemical industries.

Ideal for clean, low-viscosity fluids with moderate velocity and stable velocity, turbine flowmeters are used to measure the flow rate of liquids, gases and vapors in pipelines such as carbon oxides, chemicals, water, cryogenic liquids, air and industrial gases. High precision turbine flow meters can be used for hydrocarbon and natural gas transfer ridge lifts, and these turbine flow meters often contain the functionality of a flow computer to correct pressure, temperature, and fluid properties to achieve the accuracy required for the transponder chamber.

The vortex flowmeter is made of carbon steel, which can measure various gases and liquids such as urban pipelines and industrial sewage, gas, and natural gas.

Vortex flowmeter 316L stainless steel material This material can also be called anti-corrosion vortex flowmeter, anti-corrosion vortex flowmeter its gauge material and probe are all pertetrafluorine material, also stainless steel material, it can be used to measure corrosive liquids, especially corrosive gases, such as acid and alkali solutions, etc., with the characteristics of corrosion resistance.

The material of vortex flowmeter is stainless steel or carbon steel, which is selected according to the needs of the site.

The vortex flowmeter can measure the flow rate of the medium more, mainly including the following points: 1. The vortex flowmeter can be used to measure the flow of various industrial waters, including chemical, light industry, electric power, metallurgy, building materials, petroleum and other industries.

2. Measurement of some corrosive liquids, such as sulfuric acid, hydrochloric acid, nitric acid, acetic acid and other acids, as well as various chemical solutions.

3. Flow measurement of some low-viscosity oils, such as gasoline, kerosene, diesel, as well as heavy oil and residual oil with reduced viscosity after heating.

All vortex flowmeters are based on the Karmen vortex principle, a phenomenon observed and studied by the American-Hungarian scientist von Kármán in 1911: when a fluid bypasses a non-fluid linear object, paired, alternately arranged, and reversed antisymmetric vortices are generated on the left and right sides of the object's wake. The generation of this vortex has a periodic, alternating nature, and the frequency of change is proportional to the velocity of the fluid, which is the Karmen vortex street phenomenon.

The vortex flowmeter is a flowmeter that uses the properties of this phenomenon to determine the velocity or flow rate of the fluid by measuring the shedding frequency of the eddy current.

After understanding the principle of vortex flowmeter, you should also know how to use the vortex flowmeter well.

After selecting the vortex flowmeter, the first thing to face is the installation of the vortex flowmeter. So what should I pay attention to when installing?

1) The flowmeter should be installed horizontally or vertically on the pipeline corresponding to the passage of the project. Due to the characteristics of the vortex flowmeter, in order to achieve accurate measurement, attention must be paid to ensure the slow pipe measurement, so the vortex flowmeter on the horizontal pipeline should generally be selected to be installed at a very low place in the pipeline, and the flow direction of the fluid should be from top to bottom when the vertical pipeline is vertical.

2) When the vortex flowmeter is used as a flow regulation, special attention should be paid to installing the flow control valve behind the flowmeter, otherwise the jet is easy to appear when the flow rate is small, and the stop flow is inversely proportional to the valve opening when the flow is adjusted.

3) The vortex flowmeter has very strict requirements for the front and rear straight pipes, and the upstream of the flowmeter should be guaranteed to have 10 to 40 times the pipe diameter, and the downstream should not be less than 5 times the pipe diameter. The length of the upstream straight pipe is determined by whether there is a right-angled bend, enlargement or reducer pipe in the upstream. In particular, it should be noted that in the case of meeting the requirements, the flowmeter should be installed as far as possible at the largest possible pipe position in the front and rear straight pipe sections.

4) Measure the temperature and pressure of the temperature and pressure point should be set at the vortex flowmeter outlet 5 times the caliber accident.

5) When installing the vortex flowmeter, it is necessary to avoid strong vibration and power frequency interference signals as much as possible, and if these situations cannot be avoided, measures such as shock absorption and shielding should be taken to minimize interference.

6) In high-temperature pipelines, vortex flowmeters must be installed vertically downward.

After the installation is realized, how should the vortex flowmeter be maintained?

The vortex flowmeter has no moving parts, so under normal use, there is less maintenance required. The mission of routine maintenance is: to see if the accumulation of instrument indication is normal; Check whether the power supply of the meter is normal; Check whether the instrument body connection is damaged and corroded; Check whether there is damage and corrosion to the external circuit of the instrument; Check whether there is any leakage at the connection between the surface body and the process pipeline; Check whether the instrument electrical junction box and electronic component box are well sealed.

When the measured medium is dirty or easy to scale, the inner wall of the flowmeter should be cleaned regularly, and the vortex generator and the detection probe should be protected during cleaning, and care should be taken not to damage its surface and edges. The end cover of the detection amplifier housing should be properly screwed down after wiring and debugging to ensure its tightness. Liquids and debris should not be left in the shell during maintenance inspections.

The selection of vortex flowmeter mainly confirms the following parameter requirements:

1. Measuring medium. Turbine flowmeter is a kind of velocity flowmeter, which uses the principle of Kármán vortex street, when the medium passes through the vortex generator, it will form a small vortex in the back, and through the number of vortices, it can be converted into the flow rate of the medium, and then converted into the flow rate of the medium. Its principle determines the type of measuring medium, which can be liquid, gas or vapor.

At present, most industrial occasions, such as nitrogen, compressed air, steam, heat transfer oil, etc., are mostly measured by vortex flowmeters.

2. Pipe diameter. According to the different installation methods, the vortex flowmeter can be divided into pipeline type and plug-in installation. For the pipeline type, the pipe diameter is the same as most other flow meters, the small is DN15, and the large can reach DN300.

If a larger caliber is required, you can choose to install it by plug-in, and the conventional caliber range can reach DN2000, and the caliber above DN2000 will be supplied according to the agreement.

3. Measurement accuracy. There are also several levels of accuracy of vortex flowmeters, and they are classified according to the measurement medium. Pipeline vortex flowmeter, if it is for liquid measurement, the measurement accuracy can reach the level, and for gas measurement, the accuracy can reach the level.

If it is a plug-in vortex flowmeter, the accuracy can reach level and level.

4. Medium temperature. Generally speaking, it is divided into three ranges, which are divided into normal temperature, medium temperature and high temperature. The temperature range is -40 100 (250 for normal temperature (320 for medium temperature).

If the temperature of the medium in the field is higher, such as some superheated steam, it can be measured with an orifice flowmeter.

5. Nominal pressure. Mainly according to the installation method, the main demand in the market is the following categories, such as flange card type (flange connection type (, plug-in installation type (.

6. Power supply. According to the current market demand, there are mainly +12VDC (three-wire pulse output), +24VDC (three-wire pulse output type and two-wire current output type) lithium battery and dual power supply.

7. Output signal. According to the current market demand, there are mainly voltage frequency pulse output, two-wire 4-20mA output and HART output. In addition, in some cases where digital output may be required, we can also provide RS485 communication with Modbus.

The selection of vortex flowmeter needs to take into account the following factors: 1Measuring medium type:

Different media types have an impact on the measurement of vortex flowmeters, e.g. high viscosity or corrosive substances can accelerate damage to sensor components. 2.Measure Pipe Type:

The vortex flowmeter needs to be consistent with the diameter of the pipeline to be measured, and ensure the concentricity of the pipeline and the flowmeter. 3.Measuring range and accuracy:

The measurement range and accuracy of the vortex flowmeter are important considerations in the selection. 4.Working environment conditions:

Environmental conditions can also affect the measurement accuracy of vortex flowmeters. For example, in low-temperature environments, it is necessary to use a freeze-proof design and ensure that the transmission line is not damaged by cold climates. In extreme climates, safety measures such as risk issues need to be considered.

5.Signal output mode: The signal output mode of vortex flowmeter needs to be selected according to the actual application requirements.

Common signal output methods include pulse output, 4-20mA current signal, etc.

The vortex flowmeter is selected from the three major elements of measuring medium, temperature and pressure, and it can measure a wide range of media, including gases, liquids and steam.

It depends on whether the gas measuring belt has temperature and pressure, compensation, and what kind of gas you have.

The unit of gas flow is nl min, which is read as standard liters per minute, which means 0 degrees Celsius, and the gas flow rate is how many liters per minute under the standard condition before the quiet defeat of 1 atmosphere.

n indicates the standard state. The standard status is 0, 1ATM, and sometimes abbreviated as non-standard H-1. The relationship between the two is equal.

The conversion relationship with the cube is as follows:

1000nl/min=1nm3/min

nm3／h=1000l/60min=

The flow rate formula measured by the vortex flowmeter.

The volume flow rate qv in the pipeline is.

qv=πd2u/4=πd2mdf/4sr

k=f/qv=[πd2md/4sr]-1

Vortex flowmeter.

Under specific flow conditions, a part of the fluid kinetic energy is converted into fluid vibration, and its vibration frequency has a definite proportional relationship with the flow rate (flow rate), and the flowmeter working according to this principle is called a fluid vibration flowmeter. At present, there are three types of fluid vibration flowmeters: vortex flowmeters, precession (vortex precession) flowmeters and jet flowmeters.

1) The output is the pulse frequency, which is proportional to the actual volume flow rate of the measured fluid, and it is not affected by the fluid composition, density, pressure and temperature;

2) The measurement range is wide, and the general range can reach more than 10:1;

3) Accuracy is at the upper middle level;

4) No moving parts, high reliability;

5) The structure is simple and firm, easy to install, and the maintenance cost is low;

6) Wide range of applications, can be applied to liquids, gases and vapors.

How it works. A vortex generator (resistance fluid) is set in the fluid, and regular vortices are alternately generated from both sides of the vortex generator, which is called a Karman vortex street, as shown in Figure 1. The vortex columns are arranged asymmetrically downstream of the vortex generator. Let the frequency of the vortex be f, the average velocity of the measured medium flow is u, the frontal width of the vortex generator is d, and the diameter of the surface body is d.

f=sru1/d=sru/md

Vortex generators.

1) It can control the synchronous separation of the vortex in the direction of the axis of the vortex generator;

2) In a wide range of Reynolds numbers, there are stable vortex separation points, which maintain a constant Straubhar number;

3) It can produce a strong vortex street, and the signal-to-noise ratio of the signal is high;

4) The shape and structure are simple, which is convenient for processing and standardization of geometric parameters, as well as the installation and combination of various detection elements;

5) The material should meet the requirements of fluid properties, corrosion resistance, abrasion resistance, and temperature change resistance;

6) The natural frequency is outside the frequency band of the vortex signal.