The Study On Measurement Of Coal Water Content Based On Standing Wave Theory

Coal moisture content is the important standards of coal value. It plays an important role in production, trade, processing and usage of coal, basic theoretical research and so on, the development trend of measuring method for measuring the water in coal technology is limited. At present, the measurement on the water content of coal have a same technology bottleneck which is refer to lack of convenient non-destructive exact and low-cost coal water content measuring instrument. Therefore, all accurate, a rapid and simple measuring method for measuring the water in coal is desiderated. In this essay, referring to the principle of permittivity, the author try to utilize standing wave ratio of the microwave transmission line theory to measure coal water content.By the way of changing other polarization forms except electronic polarization form to corresponding electronic polarization form and considering the effect of temperature on the permittivity, the mathematical model of total moisture in coal, permittivity and temperature is finally established. This paper illustrates the principle of measuring medium dielectric constant with standing wave, and proves the feasibility of measuring coal water content with it by using the transmission line principle. The author also calculates the characteristic impedance of the sensor and designs the probe structure and the length of the transmission line.According to this principle, the author develop the high-frequency signal source? the detection circuit, amplifier circuit?temperature detecting circuit and the MCU data processing system. On this basis, research and design a coal moisture sensor, which can measure the moisture and temperature coal Simultaneously. Then a large number of experiments are carried out, the experimental data are compared with the conventional verification drying method. Experiments show that the measurement method is entirely feasible, the sensor system has the high accuracy, the measurement result data are very accurate. There are high correlation of the fitted curve between the measurement data and the real values.