Device for real-time measurement of fluid conductivity by use of electromagnetic method

Abstract

The invention belongs to the technical field of electromagnetic induction, in particular relates to a device for real-time measurement of fluid conductivity by use of electromagnetic method, and aims at the conditions of low fluid conductivity, and little effect on the amplitude of electromagnetic mutual inductance signals; the device uses a method of excitation frequency adjusting and phase component extracting to replace the amplitude for extraction of useful information to the maximum in order to obtain the most accurate measurement results; aiming at the condition that the measurement of fluid conductivity by use of the electromagnetic method is susceptible to the interference of the surrounding electromagnetic environment, the device uses a method of real-time calibration and probe shielding to prevent measurement result drift caused by electromagnetic interference; and aiming at the problem that the high frequency signal transmission is susceptible to noise interference when the fluid conductivity is low and the excitation signal frequency is high, the device uses a method of coaxial cable shielding for signal transmission to ensure the signal stability and reliability.

Description

technical field [0001] The invention belongs to the technical field of electromagnetic induction, and in particular relates to a device for real-time measuring fluid conductivity by electromagnetic method. Background technique [0002] Conductivity is one of the important characteristics of fluids and is widely used in water quality monitoring, medicine and health, scientific research and industrial production processes. Compared with metal materials with higher conductivity, due to the influence of their own concentration distribution, unstable form, temperature and other factors, it is difficult to achieve accurate and rapid measurement of fluid conductivity. The most commonly used methods are electrode method and electromagnetic method. [0003] The electrode method is also called the electrochemical method. Most of the conductivity measuring instruments currently used are based on this principle, but the electrode method still has some particularities and limitations in...

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Problems solved by technology

[0003] The electrode method is also called the electrochemical method. Most of the conductivity measuring instruments currently used are based on this principle, but the electrode method still has some particularities and limitations in actual measurement, such as the selection of the excitation power supply. Polarization will occur around the electrode, and the parasitic capacitance of the electrode or electrode lead will generate capacitive current when using AC power. In addition, the electrode method is a contact measurement, which will damage the measured fluid to a certain extent, and there are electrodes Long-term contact with liquid will cause problems such as corrosion, which will seriously affect the accuracy of measurement results and field practicability

Another relatively novel method is the electromagnetic induction method. The biggest advantage of this method is non-contact measurement, which overcomes some of the main shortcomings of contact measurement (conductivity method), and has a wide measurement range, accurate and fast measurement, and simple structure. , low cost and other characteristics, so it has been widely researched and applied, such as flaw detection of metal materials, film thickness measurement, parameter detection of steel production process, liquid level and conductivity measurement of fluid, etc., but in low conductivity fluid Further research is needed on the measurement of the magnetic field line. At the same time, some previous studies mostly used the amplitude of the induction signal to measure the conductivity. Since the conductivity of the electrolyte fluid is generally relatively low, the attenuation of the amplitude of the magnetic field line after passing through the fluid is very small. The main performance is Changes in the phase of the mutual inductance signal

As a result, the measurement accuracy is insufficient and the measurement range is not large enough

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