Research On Sulfitation Intensity Fuzzy-PID Control System For Canned Sulphur Dioxide Applied In Sugar Clarification

At present, domestic sugar refineries generally adopt sulfurous method to clarify cane juice, use sulfur gas produced by burning sulfur as clarificant for sulfitation neutralization process in sugar clarification. The method that sulfur gas fumigate neutral juice has many problems that sulfur burning is not complete, sulfur dioxide concentration is difficult to control and sulfitation intensity is not stable etc. It easily cause serious consequences, such as environment pollution, high energy consumption, residual sulfur content exceed standard in refined sugar. Consequently, this paper considers that compressed and canned sulfur dioxide replaces sulfur gas to use for sugar clarification.After the necessary procedures of decompression, gasification, desiccation, filtration, proportioning and mixture, compressed and canned liquid sulfur dioxide can be turned into gaseous sulfur dioxide with a certain concentration, which can just be used for sugar clarification.According to the process requirements of the canned sulfur dioxide applied to sulfitation neutralization reaction, the cascade ratio control system is designed in this paper, in which, the main and auxiliary materials are sulfur dioxide and air respectively, the control objective is sulfitation intensity. Moreover, as the system has characteristics of nolinear, long time delay and time variation etc, in order to obtain good sulfitation intensity control effect, fuzzy control and PID control are combined to use for sulfitation intensity cascade loop. The simulation model of sulfitation intensity cascade ratio control system is built based on MATLAB/Simulink, under conditions of PID control and Fuzzy-PID control adopted in cascade loop separately, the system is simulated. The simulation results show that, compared to the control effect of PID, Fuzzy-PID adopted by sulfitation intensity controller is more effective, which can well solve the problems of control accuracy and stability of sulfitation intensity etc, while canned sulfur dioxide used for sulfitation neutralization process.In order to make sulfitation intensity Fuzzy-PID control system applied to actual production, PLC and fuzzy control are combined, Fuzzy-PID control algorithm is implemented by programming based on direct look-up table method and S7-200 PLC. Meanwhile, monitoring system is designed, which is mainly composed of upper computer smart700IE HMI and subordinate computer S7-200PLC. The rationality and feasibility of sulfitation intensity control system are confirmed by simulation experiment.