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Industry Information
Gas vortex flowmeter is based on the Carmen vortex principle
2012-2-24 8:36:19

主要用于工业管道中蒸汽介质流体的流量测量,蒸汽涡街流量计特点是压力损失小,量程范围大,精度高,在测量工况体积流量时几乎不受流体密度、压力、温度、粘度等参数的影响。 The DEC-LU series gas vortex flowmeter is mainly used for the flow measurement of steam medium fluid in industrial pipelines. The characteristics of the steam vortex flowmeter are small pressure loss, large range and high accuracy. Influence of parameters such as fluid density, pressure, temperature, viscosity, etc. No moving mechanical parts, so high reliability and low maintenance. Instrument parameters can be stable for a long time. If a triangular cylindrical vortex generator is set in the steam fluid, regular vortices are alternately generated from both sides of the vortex generator. This vortex is called a Carmen vortex. As shown in the figure on the right, the vortex row is asymmetrically downstream of the vortex generator arrangement.
Suppose the frequency of vortex occurrence is f, the average flow velocity of the measured medium is, the width of the front surface of the vortex generator is d, and the diameter of the surface body is D, then the following relationship can be obtained:
f = SrU1 / d = SrU / md (1)
Where U1 is the average flow velocity on both sides of the vortex generator, m / s;
Sr-Strauhal number;
m-the ratio of the arcuate area on both sides of the vortex generator to the cross-sectional area of the pipe
qv = πD2U / 4 = πD2mdf / 4Sr (2)
K = f / qv = [πD2md / 4Sr] -1 (3)
In the formula, K is the meter coefficient of the flow meter, and the number of pulses / m3 (P / m3).
K is related not only to the geometry of the vortex generator and the pipeline, but also to the Strouhal number. The Strouhal number is a dimensionless parameter, which is related to the shape of the vortex generator and the Reynolds number. Figure 2 shows the relationship between the Strawhall number of the cylindrical vortex generator and the Reynolds number of the pipeline. It can be seen from the figure that in the range of ReD = 2 × 104 ~ 7 × 106, Sr can be regarded as a constant, which is the normal working range of the meter. When measuring the gas flow, the VSF flow calculation formula is (4)
Figure 2 The relationship between the Strouhal number and the Reynolds number, where qVn, qV are the volume flow under standard conditions (0oC or 20oC, 101.325kPa) and working conditions, m3 / h;
Pn, P-absolute pressures under standard conditions and working conditions, Pa;
Tn, T-the thermodynamic temperature under standard conditions and working conditions, K;
Zn, Z-the gas compression coefficients under standard conditions and working conditions, respectively.
It can be seen from the above formula that the pulse frequency signal output by VSF is not affected by the fluid physical properties and composition changes, that is, the meter coefficient is only related to the shape and size of the vortex generator and the pipeline within a certain Reynolds number range. But as a flow meter needs to detect the mass flow in the material balance and energy measurement, the output signal of the flow meter should monitor the volume flow and fluid density at the same time. The fluid properties and components have a direct impact on the flow measurement.
Gas vortex flowmeter is a new type of flowmeter for measuring fluid flow in closed pipes based on the Carmen vortex principle. Because of its good medium adaptability, it can directly measure the working volume flow of steam, air, gas, water, and liquid without temperature and pressure compensation. Equipped with temperature and pressure sensors, it can measure standard volume flow and mass flow, which is throttling. The ideal replacement for the flow meter.
的耐高温及抗振动性能,我公司新近开发出了SKLUG改进型涡街流量传感器,因其独特的结构和选材使该传感器可在高温(350℃)、强振动(≤1g)的恶劣工况下使用。 In order to improve the high temperature resistance and vibration resistance of gas vortex flowmeters , our company has recently developed an improved SKLUG vortex flow sensor. Due to its unique structure and selection of materials, the sensor can be used at high temperature (350 ° C) and strong vibration ( ≤1g) Use under severe conditions.
In practical applications, the maximum flow rate is often much lower than the upper limit value of the meter. As the load changes, the minimum flow rate is often lower than the lower limit value of the meter. The meter is not working in its optimal working section. One problem is usually to reduce the diameter at the measurement site to increase the flow velocity at the measurement site, and choose a smaller diameter instrument to facilitate the measurement of the instrument, but this method of diameter reduction must have a straight length of 15D or more between the reducer and the instrument. Pipe sections are rectified, making processing and installation inconvenient. The LGZ variable diameter rectifier developed by our company has a circular arc shape. It has multiple functions of rectifying, increasing the flow rate and changing the flow rate distribution. Its structure size is small, only 1/3 of the inner diameter of the process tube. It is integrated with the vortex flowmeter. Not only does not need to add another straight pipe section, it can also reduce the requirements for the straight pipe section of the process pipe, and the installation is very convenient.
For the convenience of use, the battery-powered on-site display gas vortex flowmeter adopts micro power consumption high-tech. It can be operated for more than one year without interruption by using lithium battery. Flow, cumulative flow, etc. The temperature compensation integrated vortex flowmeter also has a temperature sensor, which can directly measure the temperature of the saturated steam and calculate the pressure, thereby displaying the mass flow of the saturated steam. Temperature and pressure compensation integrated type with temperature and pressure sensors for gas flow measurement can directly measure the temperature and pressure of the gas medium, thereby displaying the standard volume flow of the gas.
采用压电应力式传感器,可靠性高,可在-20℃~+250℃的工作温度范围内工作。 The gas vortex flowmeter uses a piezoelectric stress sensor with high reliability and can work in the operating temperature range of -20 ° C to + 250 ° C. It has analog standard signal and digital pulse signal output. It is easy to be used with digital systems such as computers. It is a relatively advanced and ideal flow meter.
Measurement medium: gas, liquid, vapour
◆ Flange connection caliber selection: 100, 150, 200
◆ Flow measurement range Normal measurement flow range Reynolds number 1.5 × 104 ~ 4 × 106; gas 5 ~ 50m / s; liquid 0.5 ~ 7m / s
Normal measurement flow range See Table 2 for liquid and gas flow measurement ranges; Table 3 for vapor flow range
◆ Measurement accuracy 1.0 grade 1.5 grade ◆ Temperature of measured 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
◆ Pulse duty is about 50%, transmission distance is 100m
◆ Pulse current remote transmission signal 4 ~ 20 mA, transmission distance is 1000m
◆ Using ambient temperature of the meter: -25 ℃ ~ + 55 ℃ Humidity: 5 ~ 90% RH50 ℃
◆ Material stainless steel, aluminum alloy ◆ Power source DC24V or lithium battery 3.6V
◆ Explosion-proof grade intrinsically safe iaIIbT3-T6 protection grade IP65