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Introduction to the important position of the plug-in electromagnetic flowmeter

The important position of plug-in electromagnetic flowmeter
The measurement of flow plays an important role in the implementation of total water control, quota management and petrochemical production and process control. Mainly to reduce pollution, save water and reduce emissions, must strictly measure and control domestic water, industrial water, circulating water and discharged sewage.
The working principle of the plug-in electromagnetic flowmeter is based on Faraday's law of electromagnetic induction. When measuring the flow rate, the liquid flows through a magnetic field perpendicular to the flow direction, and induces a voltage proportional to the average flow rate (volume flow rate). The induced voltage signal is detected by two electrodes in direct contact with the liquid and transmitted to the smart transmitter through a dedicated cable. The smart transmitter is operated according to the magnitude of the potential and the mathematical model of the electromagnetic flow, and is converted into a flow signal (including instantaneous The quantity and the cumulative amount are displayed on the spot, and the 4-20MA and 1~5 VDC signals of the flow standard are output to the flow secondary instrument or DCS.
Sewage treatment capacity and treatment quality are important indicators of the water supply device. If the treatment capacity is low, the water requirement of the whole plant cannot be met. If the treatment quality is low, the discharge requirement cannot be met. Investigating the water discharge capacity and economic benefits of mine water mainly considers three flow indicators, namely mine water inflow, clarified water outflow and sludge outflow. Taking into account the cost and other factors, the author selects the plug-in electromagnetic flowmeter on the pipeline above Φ250mm, and carries out the pressure installation. After nearly 5 months of running test, the flowmeter has good application effect and the flowmeter volume is relatively accurate.
Plug-in electromagnetic flowmeters are mainly composed of sensors, smart transmitters and dedicated cables.
(1) The sensor is composed of an electrode and an excitation coil, and its function is to generate a corresponding induced potential (5 to 60 mV) on the electrode according to the speed at which the conductive medium (fluid) flows through the excitation coil.
(2) The function of the smart transmitter is to amplify the induced potential signal of the sensor, and then calculate according to the mathematical model and formula of the potential flow, and obtain the flow result and the standard flow signal. Adjustment of various flow parameters and setting of calibration parameters are performed on the smart transmitter.
(3) The function of the dedicated communication cable is that the sensor transmits a millivolt potential signal to the smart transmitter, and the smart transmitter provides an oscillating voltage to the excitation coil. Since the potential signal is a weak signal of 5 to 60 mV, the excitation signal is an oscillating signal of a high frequency and a low amplitude, so the cable should fully consider shielding and anti-interference. The length of the cable is proportional to the cross-sectional area and proportional to the conductance of the medium. The stronger the conductive characteristic, the farther the transmission distance is. The general transmission distance is 20-500 m.

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