Electrical Control System For BOPP Pelletizer

The market demand of BOPP (Biaxially Oriented Polypropylene) will become more and larger with the rapid development of the plastic chemical industry. The realization of automation for BOPP film production line and the full utilization of waste materials have high economic interest and social value. As a assistant mechanical, pelletizer in BOPP film production line can achieve not only the recovery of waste film but also the regeneration of grain, which has a great significance for reducing the production cost of the entire production line. In this paper, we design the electrical control system of pelletizer for the domestic BOPP film chemical plant and complete multi-variable system decoupling control.In this paper, the technology of pelletizer is first to be illustrated. Then, the control method of pelletizer is analyzed. Finally, the electric control system of pelletizer is implemented. We mainly design the transmission feed, cutting compaction and extrusion plastics control unit for this project. In the hardware design of pelletizer electrical control system, a siemens PLC controller as control core is used in this control system. Its function is to control speed control module, temperature control modules, and automatic replacement filter control module of extruder. We also complete the electrical control system configuration based on the PROFIBUS-DP bus network. In the software design of pelletizer electrical control system, the process control program and the multi-loop temperature PID control algorithm are completed by PLC's software-STEP7, which is easy-to-read and easy to achieve.After analyzing the reasons of low productivity and poor stability of the pelletizer, a decoupling method for pelletizer speed and temperature control system is applied in order to improve production efficiency and stability. For the features of changing parameters during pelletizer running, we propose a new algorithm of DRNN (Diagonal Recurrent Neural Network) decoupling control with integrating the traditional PID control to utilize in pelletizer. The results of simulation are showed that the algorithm can work effectively.