Choice of caliber
The choice of the diameter of the electromagnetic flowmeter is not necessarily the same as the diameter of the pipe, and should be determined by the flow rate and flow rate. However, as the chemical raw materials and intermediate liquid of Salt Lake, the viscosity is large and the flow rate is low (generally 2.0 to 4.0 m/s). The electromagnetic flowmeter is used on such a pipe, and the diameter of the sensor is the same as the diameter of the pipe. If the flow rate is lower than 1.0m/s, an electromagnetic flowmeter of appropriate flow rate can be selected to ensure measurement accuracy and relatively reduce investment.
Selection of flow rate and range
Basically, they are anti-corrosion plastic pipes, and considering the lining of the flow meter, the flow rate is generally controlled at 2m/s. For some materials that are easy to crystallize (such as sodium carbonate solution, compounding liquid: crystallized mainly boron and magnesium double salt), the flow rate is increased to 3.0 to 4.0 m/s by taking measures. The flow rate will increase the flow noise, and the vibration of the pipeline will affect the measurement accuracy. Under the condition that the electromagnetic flowmeter is installed, the shock absorber should be installed before and after. The full scale of the meter is greater than the expected maximum flow value, which is typically 1.2 times the estimated maximum flow. The normal measurement flow is greater than 50% of the full scale of the meter to ensure a certain measurement accuracy.
Vortex flowmeter selection
(1) Selection of vortex flow transmitter
In the measurement of saturated steam, VA type piezoelectric vortex flow transmitter is adopted. Because of the wide range of vortex flowmeter, in practical applications, it is generally considered that the flow of measuring saturated steam should not be lower than that of vortex flowmeter. The lower limit, that is to say, the fluid flow rate must not be less than 5 m/s. According to the size of the steam, the vortex flow transmitters with different calibers are selected, and the caliber of the transmitter cannot be selected by the existing process pipe diameter.
(2) Selection of pressure compensation pressure transmitter
Since the saturated steam line is long and the pressure fluctuates greatly, pressure compensation must be adopted. Considering the corresponding relationship of pressure, temperature and density, only pressure compensation can be used in the measurement, because the saturated steam pressure of Mingtong Company is 0.3-0.7MPa. Range, the range of pressure transmitter can be selected 1MPa.
(3) Display instrument selection
Display instrument intelligent flow display instrument with voltage regulation compensation, instantaneous flow display and cumulative flow accumulation function.
The flowmeter weighing impulse flowmeter that measures the flow using the impulse theorem is used to measure the flow rate of the granular solid medium, and is also used to measure the flow rate of the mud, the crystalline liquid, and the abrasive. Flow measurement ranges from a few kilograms per hour to nearly 10,000 tons. The typical instrument is a horizontal force-separated impulse flowmeter. The measurement principle is that when the measured medium falls freely from a certain height h to a detection plate with a tilt angle, an impulse is generated, and the horizontal force component of the impulse is proportional to the mass flow rate. Measuring this horizontal component can reflect the mass flow.
The electromagnetic flowmeter is made by applying the electric conductor to generate an induced electromotive force in a magnetic field, and the induced electromotive force is proportional to the flow rate, and is measured by measuring the electromotive force to reflect the flow of the pipeline. Its measurement accuracy and sensitivity are high. Industrially used to measure the flow of water, slurry and other media. The maximum diameter can be measured up to 2m, and the pressure loss is extremely small. However, media with low conductivity, such as gas and steam, cannot be used.
The electromagnetic flowmeter has a high cost, and the signal is susceptible to external magnetic field interference, which affects the wide application in industrial tube flow measurement. To this end, the product is constantly improving and updating, to the development of computer.