（1） Technical parameters of steam flowmeter operation

1) Measurement media: liquid, general gas, natural gas, steam (saturated steam and superheated steam);

2) Possible measurement range: Reynolds number ranging from 5 × 103 to 7 × 106

3) Normal measurement range: Reynolds number from 2 × 104 to 7 × 106

4) Measurement flow rate range: liquid 0.5-7m/s, gas 4-35mm/s, steam 7-70m/s

5) Temperature of the tested fluid:- 40℃～+300℃

6) Temperature of the tested fluid: 1.6, 4, 25MPa

7) Accuracy: Level 1, Level 1.5, Level 0.5 (Level 0.5 can only be achieved through nonlinear tuning);

8) Repeatability: 0.2% of the indicated value;

9) Table body material: ICr18Ni9Ti；

10) Pressure loss: △=1.2 × r × V2 × 10-6. In the equation: △ P - pressure loss r - measured fluid density (Kg/m3) v - average flow velocity inside the pipe (m/s)

11) Environmental temperature: -20 ℃~+55 ℃ (special requirements for ordering instructions)

12) Environmental humidity: ≤ 90%RH

13) Atmospheric pressure: 86-106KPa

14) External power supply: 3.6-224VDC

15) Internal power supply: 3-4.5VVDDC

16) Working power supply: 80/A

17) Operating voltage: 2.7-3.6V

18) Operating frequency: 0.1-3000H

19) Signal transmission distance: 100mm

20) Signal output: Pulse output (external power supply) Current output 4-20mADC (two-wire external 24VDC power supply) Pulse output and current output can only be selected in one way.
（2） Specifications and measurement range

Vortex flowmeter is 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. The vortex flowmeter adopts a piezoelectric stress sensor with high reliability and can operate within the working 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.

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 such as rectification, increasing flow velocity, and changing flow velocity distribution. Its structural size is small, only one-third of the inner diameter of the process pipe, and it is integrated with the vortex flowmeter. 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 the convenience of use, the battery powered local display vortex flowmeter adopts low-power high-tech. It can operate continuously for more than a year with lithium battery power supply, saving the procurement and installation costs of cables and display instruments. It can display instantaneous flow, cumulative flow, etc. on site. The temperature compensated integrated vortex flowmeter also comes with a temperature sensor, which can directly measure the temperature of saturated steam and calculate the pressure, thereby displaying the mass flow rate of saturated steam. The temperature pressure compensation integrated type is equipped with temperature and pressure sensors, which can directly measure the temperature and pressure of the gas medium for gas flow measurement, thereby displaying the standard volume flow rate of the gas.principle
When a triangular cylindrical vortex generator is set up in the fluid, regular vortices are alternately generated from both sides of the vortex generator, which are called Karman vortices. As shown in Figure 1, 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 face of the vortex generator is d, and the diameter of the body is D, the following relationship can be obtained: f=SrV1/d=SrV/md (1)
In the formula, V1 represents the average velocity on both sides of the vortex generator, m/s；
Sr Strouhal number;
The ratio of the bow shaped area on both sides of the vortex generator to the cross-sectional area of the pipeline is the volumetric flow rate qv inside the pipeline
Qv=π D2V/4=π D2mdf/4Sr (2)
K=f/qv=[π D2md/4Sr] -1 (3)
In the formula, K represents the instrument coefficient of the flowmeter, with pulse count in m3 (P/m3).
K is not only related to the geometric dimensions of the vortex generator and pipeline, but also to the Strouhal number. The Strouhal number is a dimensionless parameter that is related to the shape of the vortex generator and the Reynolds number,
Figure 2 shows the relationship between the Strouhal number of a cylindrical vortex generator and the Reynolds number of a pipeline. As shown in the figure, Sr can be regarded as a constant within the range of ReD=2 × 104 to 7 × 106, which is the normal operating range of the instrument. When measuring gas flow rate, the flow calculation formula for VSF is (4)

Figure 2: The relationship curve between Strouhal number and Reynolds number
In the equation, qVn and qV - represent the volumetric flow rates under standard conditions (0oC or 20oC, 101.325kPa) and operating conditions, respectively, m3/h；
Pn and P - are the absolute pressures under standard and operating conditions, respectively, Pa；
Tn and T - are the thermodynamic temperatures under standard and operating conditions, respectively, K；
Zn and Z - are the gas compression coefficients under standard and working conditions, respectively.
As can be seen from the above equation, the pulse frequency signal output by VSF is not affected by fluid properties and composition changes, that is, the instrument coefficient is only related to the shape and size of the vortex generator and pipeline within a certain Reynolds number range. However, in material balance and energy measurement, the rotary flowmeter needs to detect mass flow rate. At this time, the output signal of the flowmeter should simultaneously monitor volume flow rate and fluid density. Fluid properties and components still have a direct impact on flow measurement.

Steam vortex flowmeterCaliber and Flow Selection Table

Vortex Flowmeter	Nominal diameter DN (ｍｍ)	Flow range (m)３／ｈ）
		Liquid	Gas	Steam
LUGB	250	100~1000	1000~8000	930~8000
LUGB	300	150~1500	1500~11500	1330~11440
LUGB	350	200~2000	2000~15600	1800~15600
LUGB	400	250~2500	2500~20000	2400~20000
LUGB	500	400~4000	4000~30000	3700~31800
LUGB	600	500~5000	5000~45000	5300~45800
LUGB	700	700~7000	7000~60000	7300~62300
LUGB	800	900~9000	9000~80000	9500~81400
LUGB	1000	1400~14000	14000~120000	14800~127200