Study On The Slurry Noise Of The EMF Based On The Specificity Analysis Of The Slurry

The electromagnetic flow meter has the following advantages: simple structure, large measurement range, high measurement accuracy, good corrosion resistance, low demand for velocity distribution, reliable, convenient maintenance and long life. So in various fields of engineering technology, the electromagnetic flowmeter is widely used in the measurement of the slurry. When the electromagnetic flow meter is used to measure the slurry, the output signal has a fluctuation phenomenon, which is the slurry noise. The effect of the slurry noise on the measurement is harmful, so it is great significance to study the problem of the slurry noise produced by the electromagnetic flow meter in measuring the slurry, analyze the causes and to take measures to reduce or eliminate its influence on the measurement. The study on the problem of the slurry noise is one of the hot spots in the research field of the electromagnetic flowmeter. At present, domestic and foreign scholars and technical workers have carried out a lot of research on the problem of the slurry noise, a lot of research findings have been made. However, at present the research mainly focuses on the improvement of the electromagnetic flowmeter converter to overcome the influence of the slurry noise on the flow signal, the research on the characteristics of the noise of the slurry is still to be further studied and perfected. In addition, there are many problems and shortcomings in the existing research on the method of overcoming the slurry noise. Based on the above background, this paper mainly focuses on the characteristics of the slurry noise of the electromagnetic flow meter, And according to the research results, in view of the shortcomings of existing methods for solving the problem of the slurry noise, an improved method of electromagnetic flowmeter sensor is proposed to overcome the influence of the slurry noise on the measurement signal, and the correctness and feasibility of the proposed method are verified by experiments. The main work of this paper is as follows:1) The important theory and the research results of the predecessors in the field of the slurry type electromagnetic flow meter and the solution of the slurry noise are summarized. By the analysis of the problems and shortcomings, the research ideas and research route are proposed, and the necessary foundation for the following work is provided. The work lay a solid foundation for the study of this paper.2) Based on CFD method, the flow field of slurry is analyzed. A method for obtaining the entrance length of the liquid solid two phase flow to ensure the distribution of the slurry solid particles to achieve a steady state is proposed. In theory, the reason of the slurry noise of the electromagnetic flowmeter and relationship between the intensity of the slurry noise and the electromagnetic flow sensor is clarified. These work provides support for the subsequent analysis of the characteristics of the slurry noise.3) The slurry noise was studied by using the method of random signal power spectrum estimation. According to the 1/f characteristics of the slurry noise, the mathematical model of the slurry noise is established by ARMA model. The relationship between the intensity of the slurry noise and the concentration and velocity of the slurry is described by the simulation of the power spectrum density curve of the slurry noise. This study provides a theoretical basis for the improvement plan for of the electromagnetic flow sensor to overcome the slurry noise.4) In view of the shortcomings of existing methods that is increase excitation frequency of electromagnetic flow meter for solving the problem of the slurry noise, A method for improving the structure of electromagnetic flow sensor is proposed, the method can avoid the impact of the solid particles of the slurry on the measuring electrode, so as to achieve the purpose of overcoming the slurry noise. Through the research on the factors affecting of the flow measurement, the improved method is established.5) According to the improved method, the electromagnetic flow sensor was designed and produced. The sensor is verified to be able to meet the accuracy level required of the flow measurement by the calibration experiment, and the flow measurement experiment of the sensor is carried out in the slurry device, the experimental results show that the method can effectively overcome the disturbance of the slurry noise to the measurement signal.