Research On Process Control Of Calcium Saponification Rare Earth Extraction Based On PetriNet

Rare earth has incomparable properties of common metals,and due to scarce reserves and difficult processing and purification,the market is in short supply,which has been listed as an important strategic resource in China,The research on the process control of calcium saponification of rare earth extraction is of great significance to improve the quality of rare earth products and extraction efficiency.At present,the vast majority of rare earth enterprises saponification process is still manually operated,experience-based control,in a relatively backward state.This paper takes the calcium saponification process of Rare earth enterprise as the research background.Through field investigation,it is found that the process belongs to intermittent chemical production and is a typical discrete event dynamic system,which is difficult to be analyzed by conventional modeling method.Petri net has a good function of discrete expression and process description.Based on Petri net theory,this paper presents an in-depth research on the modeling and control of rare earth extraction calcium saponification process.The main research contents and conclusions are as follows:Firstly,the technological process was analyzed,and the control model of calcium-saponified Petri net was constructed with technological standards as constraints.The model structure was optimized by changing the virtualization method of the place,and the control process was established and the Petri net controller was designed with the established model as control strategy.Secondly,saponification value variables in the process need to be measured by manual experiment.In view of the time-consuming and laborious problem of such off-line determination,this paper constructed a decision model based on the principle of BP neural network to realize the saponification value decision function for online prediction of saponification value variables.The test results show that the decision deviation rate is within ±2%.Thirdly,the feedback dual-degree-of-freedom PID control is used to optimize the accuracy of material addition,and the simulation results show that it has better tracking performance of set value and anti-interference performance.Finally,S7-300 is used as the controller for process control and simulation control platform design.Based on SIMIT create virtual instrument,virtual simulation actuators and controlled object,complete the Win CC simulation process monitoring control design,and use the OPC data interactive technology realizes the decision system and controller communication,calcium saponification process simulation control platform can real-time monitoring and control process.The simulation results show that Petri net is suitable for modeling calcium saponification process.Compared with manual operation,the control strategy constructed by Petri net has higher control accuracy and more stable control process.The Petri net control algorithm realized in this study can be completely transplanted into the subsequent control system developed by enterprises,which has certain application value.