Research Of A Predictive Model Of Thickness Of Ring Formation In Oxidized Pellet Rotary Kiln

With the rapid development of steel industry in China, the demand of oxidized pellets grows rapidly. But the traditional pellet process - shaft furnace has the shortage of small yield productivity and poor adaptability of raw materials, which cannot meet the growing demand of blast furnace charge. Meanwhile, roasting machine belt needs high temperature resistant alloy steel, which means the process is unable widely to promote temporarily in China. Therefore, to develop the grate-kiln process with mature technology, high production and strong adaptability of raw materials, appears especially important. But the process has a problem of ring formation which brings great trouble to improve the production and quality of pellets. So it has very important practical significance to build a predictive model of ring formation to predict the ring forming behavior in oxidized pellet kiln, and to know the real-time influence of the site operation parameters on ring formation. It has important meaning to guide the instant operation on ring formation.A heat transfer model of rotary kiln was built in this paper which based on the cylinder of the heat conduction differential equation after analyzing the heat transfer process inside the oxidized pellets kiln. And the boundary conditions were established. The thermal physical properties of ring materials were researched for the first time, and the result showed that the thermal conductivity of ring object decreases with the increasing temperature. It provided reference for the subsequent mathematical simulation of oxidized pellet kiln.Based on the correspondence between the kiln outer wall temperature and ring formation, and combined with kiln shell heat transfer model, a model of thickness of ring formation in rotary kiln was built based on certain assumptions. The model was verified correct by comparing the simulation results with site testing results.Simulation software MATLAB was used to program the thickness model of ring formation. The simulation results showed the temperature distribution along the axis of inner wall, and the thickness distribution of ring formation in different position of the rotary kiln. The calculated results of model were showed by graphical display based on the powerful graphics capabilities of MATLAB. Also a GUI of the model was designed which allowed site operators to analyze the producing process conveniently by using the simulation results of the model.The growth rate of ring was analyzed and calculated by historical temperature data. And the rate was used to predict the growth situation of ring. The MATLAB simulation results showed that the ring formation had a linear growth, which was used to predict the growth time of ring. Comparing with historical data, the predictive results were verified correct, so that it provided basis for ring forming prediction, and achieved early warning as to achieve stable operation of site equipment.