Corrosion Detection Of Tank Car Based On Eddy Current Sensor

With the rapid development of China’s national economy, petroleum and petroleum products has gradually become a major energy and chemical raw materials.There are two main mode of crude oil transportation in China now:one is the pipeline and the other one is tanker transport.Crude oil transportation often contains sulfuric acid, hydrogen, organic, inorganic salts, water and other corrosive chemicals. Adding the tank wall surrounding affected by environmental factors, tanks of life will be greatly reduced.The consequences will be very serious if the tank is not corrosion detectiontimelyand the corrosion is not processed properly.The consequences will affect the quality of oil, causing oil leaks, pollution, causing fires and explosions.According to the survey data, the economic losses accounting for 1.8%-4.2%year GNP due to tank corrosions in industrialized countries.China’s annual loss due to tank corrosion is estimated at 500 billion yuan, accounting for 5%of the total value of the national economy.Therefore, tankcorrosion detection technology has very important significance. However, existing detection methods cannot effectively detect the corrosion in a tank. Analyzed the characteristics of the various corrosion detection sensor, a new structure of eddy current sensor for tank corrosion detecting has been designed and produced in this paper.Firstly, the principle of eddy current sensor has been analyzed. Tank size is too large, sothe tank is equivalent to a carbon steel plate which is 20x20 mm large and 5 mmthick.Excitation coil and detection coil shape and eddy current sensor structure has been determinedaccording to their different roleinthe detection system. By finite element analysis, excitation coil and the detected size are determined. Then, the properties and the skin depth tank metal material is studied and the excitation frequency of the eddy current sensor is obtained. After calculating, the excitation coil and the enameled wire diameter andturns of the detection coil has been got. According to the above, the frame and the shell of the coil are designed.Secondly, equivalent circuit and the influence of various parameters on the sensor has been analyzed. Probe coil and the probe coil excitation signal generator are designed and produced according the analysis. Rear sensor circuit is designed and simulated in accordance with the output signal. Then concrete specimens at different depths of corrosion are tested. After analyzing the test results, linearity, accuracy and other technical parameters of the sensor are obtained.