Research And Apply Of Fuzzy Self-tuning PID Control Algorithm In Molecular Distillation Device

Molecular distillation is an effective means of separation to high boiling point and thermal sensitive material. It has gotten the attention of many countries since1930s and there is a more wide development space in the future. With the study of molecular distillation device based on the multi-stage distributed, building the modeling for the molecular distillation equipment by test method, this paper uses fuzzy self-tuning PID control algorithm and the distributed control system (DCS) principle, having achieved designing the automation equipment control system.The experiments of drawing fructus schisandrae oil by the molecular distillation method can get the best process parameters. Every subsystem are controlled by fuzzy self-tuning PID according to the set of process parameters; respectively establishing model of conventional PID control and fuzzy self-tuning PID controls using MATLAB/SIMULINK, the results show that the fuzzy self-tuning PID control strategies can achieve better control purpose, so the controller of the control system is feasible.In the paper, we have finished the molecular distillation equipment automatic control system design based on the principle of distributed control system. According to the process flow of molecular distillation, molecular distillation unit is divided into three subsystems; in each subsystem, the operator can tune and preinstall the motor speed of film blowing by open-loop manner; the paper has achieved fuzzy self-tuning PID control through the PLC, so the evaporation temperature can be controlled; choosing PC as engineer stand, touch screen (HMI) as an operator stand, we designed and realized DCS system based on PLC.The actual operation shows that the multi-stage distributed molecular distillation control system realize the automatic control of molecular distillation device, effectively reducing energy consumption, making of fructus schisandrae oil output and quality are improved, which reach the performance index and the design requirements of the control system.