The Study Of Fuzzy Control Based On PLC In Dense Medium Separation

Since 1990s, as the position of the dense medium separation in coal separation rising, many countries and their academes have done many positive researches in the field of dense medium separation, coal separation equipments and their testing and controlling system. Many harvests applied in the coal separation plants in larger and serial of separation equipments, predigest the process, full separation, coal slurry dense medium separation, dense medium circulate, modular separation plants are gained.In auto-control of the dense medium cyclone, since the extensive application of automatic measure and control instrument and the computer technology, the online control of the suspension liquid entrance pressure, the automatic measure and control of suspension liquid density, magnetic content and the liquid level, the online feedback control of ash in product, and the optimization control of the technical economic norms, were carried out The production management system, gathering automatic control and management in one were established. Using PID controller and online modified the parameter, this was generally applicatioa According to the dynamic change between each parameter in the process, the mathematics model of dense medium preparation in control system was establishedBased on each parameter (density, liquid level viscosity, pressure) in medium technique, nonlinear property and the dynamic change relation between each other were highly impossible to establish accurate mathematics model. Therefore, this program seek the solution that application fuzzy control. This control system gathered dense medium control, ash cycle control, and the central control of medium flow machine in one body, the relationship between the suspension liquid density, liquid level and shunt volume was established, using SIEMENS/S7-200 CPU 226 as the controller. Phased the dense medium suspension level. Separated the control process into working process and adding medium process, and different fuzzy control rules were established in each process, the analogue double circuits closed-loop control were established, the extemal loop of ash cycle control used PID controller, and the inner loop of given density data of suspension density and the liquid control system was given by hand, and also could be online setted by ash cycle control, reached the purpose of direct control the washed coal.As a project program of application, the detail hardware design of the control system, the selection of the measure and control equipment and the design of the partial systematic software were given in the paper. And the specific treatment in anti-interference of the system was alsogiven.