How to adjust the speed of steam flow meter

　　How to adjust the speed of steam flow meter

　　Steam vortex flowmeter is mainly used for flow measurement of steam medium fluids in industrial pipelines. Steam vortex flowmeter is characterized by small pressure loss, large range, and high accuracy. When measuring the volume flow rate under working conditions, it is almost independent of fluid density and pressure. , temperature, viscosity and other parameters.

　　1. The standard meter method device is suitable for measuring various fluids (including liquids and gases), and is also suitable for liquids of various viscosities.

　　2. When performing indication calibration, the flow meter as the standard meter and the flow meter to be tested are installed in series in the same closed pipeline system, and there is generally no time measurement error.

　　3. The vortex flowmeter used as a standard meter can be the same type as the flowmeter being tested, or it can be different.

　　4. The standard table method can be used to calibrate the flow meter without cutting off the air flow or liquid flow, so it is suitable for online calibration and is also suitable for use as a vortex flowmeter standard for closed pipelines.

　　5. The standard table method is easy to automate, is airtight and safe, and does not pollute the environment.

　　6. Small size, light weight, simple device structure, easy operation, easy transportation and installation, and low cost.

　　7. The standard meter flow meter has low accuracy and poor stability. It often needs to be compared regularly or irregularly to supervise its measurement performance. The calibration cycle of the standard meter is shorter.

　　Steam flow meter principle

　　Steam flowmeter is a special instrument for measuring the cumulative mass flow of steam. It has two structural forms: mechanical type and intelligent type. It can accurately read the flow through the indicator dial (mechanical type) or LCD screen (intelligent type) for on-site display. The meter can also output pulse signals based on the quality of all steam, and has manual pressure compensation or automatic temperature compensation functions. Due to its simple structure, moderate price and wide measurement range, this flowmeter is widely used in petroleum and petroleum, chemical industry, textile, heating and other situations where steam flowmeter is required.

　　A vortex flowmeter is a volume flowmeter that measures the volume flow rate of gas, steam or liquid, the volume flow rate under standard conditions or the mass flow rate based on the Karman vortex principle. And can be used as a flow transmitter in automated control systems.

　　The instrument adopts advanced differential technology, combined with isolation, shielding, filtering and other measures, to overcome the problems of poor shock resistance and small signal data disorder of similar products. It also adopts unique sensor packaging technology and protective measures to ensure the reliability of the product. . The product has two types: basic type and composite type. The basic type measures a single flow signal; the composite type can simultaneously measure temperature, pressure, and flow. Each type has an integral or split structure to adapt to different installation environments.

　　The measurement principle of vortex flowmeter. For saturated steam flow measurement, people generally used standard orifice flowmeters in the 1980s. However, judging from the development status of flow meters, despite its long history and wide range of applications, orifice flowmeters have not been widely studied. It is also the most sufficient and has the most complete test data. However, when using a standard orifice flow meter to measure saturated steam flow, it still has some shortcomings: first, the pressure loss is large; second, the pressure guide pipe, the three groups and the connections The joints are prone to leakage; thirdly, the measuring range is small, generally 3:1, which can easily cause low measurement values ​​due to large flow fluctuations. The vortex flowmeter has a simple structure, and the vortex transmitter is directly installed on the pipeline, which overcomes the phenomenon of pipeline leakage. In addition, the pressure loss of the vortex flowmeter is small, the measuring range is wide, and the measuring range ratio of saturated steam can reach 30 to 1. Therefore, with the maturity of vortex flowmeter measurement technology, the use of vortex flowmeters is becoming more and more popular.

　　The vortex flowmeter uses the principle of fluid oscillation to measure flow. When the fluid passes through the vortex flow transmitter in the pipeline, two rows of vortices that are proportional to the flow rate are generated alternately up and down behind the vortex generator of the triangular prism. The release frequency of the vortex is related to The average velocity of the fluid flowing through the vortex generator is related to the characteristic width of the vortex generator, which can be expressed by the following formula:

　　f=Stv/d

　　In the formula: f is the release frequency of the vortex, Hz; v is the average velocity of the fluid flowing through the vortex generator, m/s; d is the characteristic width of the vortex generator, m; St is the Stroha number, dimensionless, which The value range is 0.14-0.27.

　　St is a function of Reynolds number, St=f (l/Re).

　　When the Reynolds number Re is in the range of 102~105, the St value is about 0.2. Therefore, during the measurement, it is necessary to try to satisfy the fluid's Reynolds number between 102~105 and the vortex frequency f=0.2v/d.

　　It can be seen that by measuring the vortex frequency, the average velocity v of the fluid flowing through the vortex generating body can be calculated, and then the flow rate q can be calculated from the formula q=vA, where A is the cross-sectional area of ​​the fluid flowing through the vortex generating body. Applications: Power generation, combined heat and power, and heating industries; Aviation, aerospace, shipbuilding, nuclear energy, and weapons industries; Machinery, metallurgy, coal mining, and automobile manufacturing industries; Petroleum and chemical industries; Medicine, food, and tobacco manufacturing industries; Forestry, Agricultural reclamation and light industry, etc.