| In the process of sintering production, the moisture of sinter mixture is an important parameter. Permeability of mixture can be improved by suitable water content, which is helpful to the combustion and pelletizing of the mixture and will affect the quality of sinter directly. With the improvement of automation in metallurgical industry, automatic control of sinter mixture moisture has become the trend. As the basis of moisture control, the real-time and accurate detection of moisture has become an important link. The measurement of mixture moisture in steel plant is choosed as research object in this thesis, some research on detecting of moisture in real time was done by conductometric water-content meter.A sensor that was suitable for using in industrial environment has been designed in this thesis. The speed of the belt is 2 m/s, so the wear-resisting degree of the contact sensor must be high. The high strength wear resistant material was used as the shell, wear-resistant ceramic was used as insulating parts. The sensor could be used more than 3 months through the field test. After adding the length of wear-resisting part, the sensor is expected to be used for more than six months. Considering the situation that the sundries in the mixture are easy to accumulate in the front of the sensor, the redesign of sensor’s structure has been reasonable, solving the problem of plugging caused by the sensor effectively.The design of hardware and software has been completed. The hardware included power circuit, excitation circuit, signal processing circuit, display circuit, communication circuit, etc. The software has been written by C language, the Micro SD card’s driver based on FAT 32 file system was completed, which can achieve the real-time storage of temperature and moisture. The instrument can show moisture and the moisture can be transmitted to the central PC by 4-20 mA current signal to achieve real-time display and monitor of the moisture. The instrument can achieve the function of calibration; it can also achieve instrument calibration through the keyboard easily. The calibration data can be stored in the microcontroller’s FLASH and will not lose even if the instrument is powered off or reset. The instrument can alarm at the same time to show the temperature sensor is anomalous or the moisture is in excess of the upper or lower limits.The instrument’s temperature compensation and the experiment of static calibration have been completed by software. The temperature drift experiment showed the temperature drift is 12 mV at 45 ℃ or so, meeting the requirement of industrial field. The experiment of measuring material moisture by rapid weight-loss method has been completed, the results showed the method could meet the demand of the factory. The anti-interference ability of the moisture meter has been analyzed in the thesis, the result indicated that the moisture meter’s anti-interference ability is good.By observing the 3 conductometric water-content meters that have been installed in Tianjin Iron&steel Group CO., Ltd, the maximum absolute error of measurement is 0.3% (moisture percentage), and they run more stable than the infrared moisture meter when the material is darker or the material is changed. |
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