Overview of Research on Empty Pipe Detection Using Electromagnetic Flowmeter

With the improvement of electromagnetic flowmeter technology and its products, electromagnetic flowmeters are widely used for full pipe flow measurement, and are also widely used in some flow control with non-full pipe status. Therefore, it is hoped that the electromagnetic flowmeter can have good empty pipe detection capability to reduce the complexity of pipeline configuration. Empty pipe detection technology has therefore become one of the research contents of current electromagnetic flowmeter technology. Then this article mainly introduces the empty pipe detection of electromagnetic flowmeter.

The electromagnetic flowmeter works based on the Faraday electromagnetic induction principle. Its measurement equation is based on the condition that the fluid is full in the measuring pipe. Obviously, it is difficult to solve the problem of empty pipe detection with conventional electromagnetic flowmeter technology. In actual flow control, the main problem is to solve the flow value locking problem when the sensor is in the empty pipe state. Specifically, when the sensor electrode is partially or completely exposed from the fluid, the system should detect this state in time and make the flow value zero. This article studies the problem of empty pipe detection of electromagnetic flowmeter.

Empty pipe detection of electromagnetic flowmeter studied the empty pipe detection method based on signal analysis under spatial electric field interference and proposed the empty pipe detection technology when the spatial electric field interference makes the signal saturated. Cai Wuchang et al. studied the relative conductivity detection method based on additional excitation adopted by some domestic and foreign products. There is a product description. It is pointed out that due to the additional excitation, this method has a condition greater than 20us/cm for the fluid conductivity. Through experiments and equivalent model analysis of the empty pipe state, it is found that the interference amplitude in the empty pipe state has some uncertainty. The detection resolution of the relative conductivity detection method with additional excitation is sensitive to the length of the signal cable. Based on the amplitude change of the interference in the flow signal, combined with the unique signal processing method of the electromagnetic flowmeter. The signal characteristics in the empty pipe state are discussed. The empty pipe detection method without affecting the flow measurement performance is studied, and the relevant implementation technology is also given.