Electromagnetic flowmeter features
Using intelligent judgment, the measurement correction setting is not used, and the air traffic control alarm and electrode detection application are more convenient;
Advanced "rough error handling" technology, which can remove fluids such as slurry to measure sharp disturbances, reduce output runout, maintain high precision measurement and make output more stable;
With a fluid density setting, it can display mass flow;
Constant current excitation current range, 125mA, 250mA optional, can be used with different manufacturers, different types of electromagnetic flow sensors;
Control function with remote reset of the totalizer, with contact signal input for starting and stopping accumulation, suitable for total inspection and batch processing applications;
With self-test and self-diagnosis function;
Advanced non-volatile memory for higher circuit reliability and effective protection of setup and measurement parameters;
The meter can be equipped with an unpowered clock and memory for recording the power down time, power-on time and power-down time;
The meter has an optional hour recording function that can store flow and electrode resistance measurements for more than 30 days.
The new keyboard processing method avoids the keyboard operation affecting the measurement, and can enter and return the operation menu to make the parameter setting more convenient;
The total display uses 10-bit decimal 9999999999 full-value carry, which solves the practice of double-word full value 4294967285 (hexadecimal FFFF) carry-in habit;
With wireless transmission, the mesh network is organized by the wireless HART protocol.
The ultrasonic flowmeter is designed based on the geometrical principle that the velocity of the ultrasonic wave propagating in the flowing medium is equal to the average flow velocity of the measured medium and the velocity of the acoustic wave itself. It is also measured by the flow rate to reflect the flow rate. Although the ultrasonic flowmeter appeared only in the 1970s, it is very popular because it can be made into a non-contact type and can be connected to the ultrasonic water level gauge for opening flow measurement without disturbing or resisting the fluid. There are promising flow meters.
Ultrasonic Doppler flowmeters fabricated using the Doppler effect have received widespread attention in recent years and are considered to be ideal gauges for non-contact measurement of two-phase flow.
Fluid oscillating flowmeter
The fluid oscillating flowmeter is designed based on the principle that the fluid will oscillate when flowing under specific flow conditions, and the frequency of the oscillation is proportional to the flow velocity. When the flow cross section is constant, the flow rate is proportional to the flow volume of the pilot volume. Therefore, the flow rate can be measured by measuring the oscillation frequency. This flowmeter was developed and developed in the 1970s. Because it combines the advantages of non-rotating components and pulsed digital output, it has a promising future. At present, typical products include vortex flowmeters and spiral vortex flowmeters.
Several problems of solutions
Recalculating the differential pressure scale
Temperature and pressure compensation can only reduce the measurement error, not only can not solve the problem fundamentally, but also the measurement signal exceeds 20mA, resulting in steam leakage measurement. The transmitter measurement signal exceeds 20 mA, indicating that the actual measured differential pressure signal ΔP exceeds the design differential pressure value.
Increase temperature and pressure compensation
When the temperature and pressure of the steam change, the density of the steam changes, and the steam flow measurement produces an error. Measurement error can be reduced by temperature and pressure compensation. Since the temperature of the saturated steam is a single-valued function of the pressure, the temperature and pressure compensation of the saturated steam can be pressure compensated or temperature compensated. Because the pressure signal detection is sensitive and the compensation accuracy is high, it is compensated by pressure and realized by DCS.
Steam is a special medium. As the pressure and temperature change, the density of steam changes. Therefore, it is necessary to compensate for temperature and pressure. When the pressure and temperature fluctuation of the steam are not large, that is, when the operating condition parameters deviate from the design parameters and the influence on the measurement is small, the temperature and pressure compensation measures can achieve the purpose of accurate measurement. However, when the operating parameters deviate too much from the design parameters or the operating parameters fluctuate frequently and are too large, even with the temperature and pressure compensation, it is difficult to meet the measurement accuracy requirements. At this point, only differential pressure or flow can be recalculated for a particular throttling element.