A non-contact conductivity measurement device and method based on lc circuit

Abstract

The invention discloses a non-contact conductivity measuring device and method based on an LC circuit. The device includes an AC excitation source, an LC circuit, a ring-shaped two-electrode sensor, a current-to-voltage module, a signal processing module, a data acquisition module and a microcomputer. Among them, the ring-shaped two-electrode sensor is composed of a metal shield, an excitation electrode, a detection electrode and an insulating pipe, which can realize non-contact measurement. A metal shield is placed around the sensor to shield external electromagnetic interference. The AC excitation source provides a sinusoidal excitation signal. The LC circuit includes an inductance module and a capacitor. The two ends of the actual inductance in the inductance module are respectively connected to the AC excitation source and the excitation electrodes, and the detection electrodes are connected to the current-to-voltage module. The present invention makes the entire measurement circuit work in a low-frequency state by reasonably selecting the values ​​of the inductance L and the capacitance C of the LC circuit, that is, at a lower operating frequency, a larger fluid conductance measurement range and sensitivity can also be obtained, which is lower The conductometric measurement of conductive fluid in pipelines at operating frequency provides a useful reference.

Description

technical field [0001] The invention relates to fluid conductance detection technology, in particular to a non-contact conductance measurement device and method based on LC circuits. Background technique [0002] Fluids in pipelines widely exist in industrial processes such as metallurgy, chemical engineering, biomedicine, environmental protection and governance. Conductance is one of the most basic physical parameters of fluids, and its changes reflect the differences in many physical and chemical properties of fluids. Therefore, the online detection of conductance plays an important role in the analysis and measurement of other fluid characteristic parameters such as concentration, composition, chemical reaction rate, etc., and the research on related measurement devices and methods also has important scientific significance and industrial application value. [0003] Capacitive coupling non-contact conductivity detection technology (C 4 D) is a new type of non-contact co...

AI Technical Summary

Problems solved by technology

The first defect is that the high-frequency method increases the requirements for subsequent detection circuit components, such as the requirements for the bandwidth of the operational amplifier; the second defect is that strictly speaking, the use of the high-frequency method will make the gap between the two electrodes Conductive solution can no longer be equivalent to a resistor

Studies have shown that when the excitation frequency is higher than 1MHz, the capacitive component of the conductive solution itself cannot be ignored. At this time, the conductive solution between the two electrodes can no longer be equivalent to a resistance, and the corresponding measurement model will become very complicated.

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