Modeling And Intelligent Control Of A Rotary Dryer

Rotary dryer has been widely applied in industrial production process, being charged with the tasks of drying and conveying the large amounts of bulk or slurry material. Rotary dryer is a time-varying and nonlinear control object, with characteristics of the large inertia and long time delay. The drying process involves complex mechanism of heat and mass transfer, and is closely related to the characteristics of the drying material. It is difficult to measure the critical parameters of the process accurately and timely, therefore, the establishment of the model of a rotary dryer, which can reflect the working conditions accurately, and the implement of intelligent control are of a certain degree of difficulty.In response to these difficulties, the research purpose of the paper is to establish the hybrid mechanism model of rotary dryer. Then, based on the model, advanced intelligent control strategy is utilized to control the important variables of drying dryer, and Siemens PLC and WINCC configuration software are used to design an automatic control system of zinc concentrate rotary dryer, in order to achieve efficient production of energy-saving and emission reduction.The system's process and control requirements are analysised in the paper. Based on the thought of hybrid model and mathematical equations of heat and mass transfer, hybrid dynamic model of zinc concentrate rotary dryer is established. The key parameter drying rate of the zinc concentrate is obtained by doing least-squares fitting of experimental data of the baking experiment. Simulation results show that the hybrid dynamic model can more accurately reflect the work conditions of the zinc concentrate rotary dryer and the relationship between the variables of each parameter.On the hybrid dynamic model, the fuzzy control strategy of gas flow rate is designed in the paper, based on fuzzy control theory and neural network theories. And the problem that control rules are difficult to obtain is solved by using RBF neural network. The amount of gas flow can be regulated by the strategy based on outlet moisture content of the product, achieveing not only reduceing the outlet moisture content of zinc concentrate but also the effect of the efficient use of energy. Simulation results show that the fuzzy control strategy is effective.Based on hybrid dynamical model and the fuzzy control strategy, hardware and software of control system are designed in the paper, for example, PLC selection, hardware address of the allocation, hardware configuration, and procedures of automation process and fuzzy control, and also the monitor screen is designed by using WINCC. The control requirements of the system are fulfilled.