The Control System Of Cold Pellet Drying Section Based On PLC

Cold-pressed pellet technique occupies an increasingly important role in the smelt-ing industry with energy consumption. We face new challenge of producing pellet with low energy consumption and high quality. Drying is an important link in the process of the pellet producing, has characteristics of strong nonlinear,long time lag and many ex-ternal interference factors. The traditional method of temperature control with low pre-cision, big deviation, high sphere broken rate and influences the quality of the product seriously.This paper introduces the cold pellet technology, expounds the importance of the drying section in the whole process of production and analyzes the deficiencies of the traditional control method, then a set intelligent control system for cold pellet drying section was designed by using PLC as controller.Whole of the control scheme is conceived, whole drying control system as a main site, drying section as an affiliate site, PROFIBUS technology is used to communication. Then the system hardware was designed, the S7-300PLC, spokes weighing transducer, thermocouple and other necessary equipments are choosed.Then the cold pellet drying process and identification system is analyzed, establish the fuzzy PID temperature controller combining the fuzzy control and PID control method firstly. Then the PID controller and fuzzy controller are compared by using simulation respectively to prove the control effect is better than the other two kind of controller obviously on theoretically, the anti-interference ability of the fuzzy PID temperature controller is analyed to prove the control effect further.The fuzzy PID temperature control and intelligent control of feeding material to drying warehouse are realized in PLC. The manmachine interface is designed to realize data acquisition, alarm, process control, and report output function.Lastly the system is put into using after testing. The results show that the sphere broken rate is decreased, the product quality is improved through analysis of the data from system. It shows that the control system in real production is feasible and reach the requirement of process, the degree of automation is improved, the energy saving and emission reduction is realized.