The Research And Realization To The Control System Of Waste Oil Regeneration Process

Lubricant is a kind of important oil product in the industrial production and the life, and waste oil is a kind of renewable resources and contains the huge economic value. Now environmental regulations in our country is not mature and the reusing consciousness is not widespread, so waste oil is often treated as contaminant, which wastes resources and the pollutes environment. FKHB recycling system of waste oil is a advanced processing technology in the domestic, and it takes the Thin-Film Evaporation and Supercritical Fluid Extraction. The process avoids the traditional acid and alkali pollutants, and is worth to be promoted in Xinjiang and other areas. At present the equipment is operated mainly by labour, which affects the quality of the production.According to the control problem existing in FKHB system, the thesis divides the whole system into Flow supply device, furnace tube and Thin-Film Evaporation based on the theory analysis, then uses Recursive Least Square to ident the system model, and with the model of Supercritical Fluid Extraction for the controlled object to design controllers of PID, improved Smith compensation, the Fuzzy-PID and dynamic matrix control (DMC) by using SIMULINK. The result proves that the Fuzzy-PID controller is suitable for the temperature control of Thin-Film Evaporation, and it provides the theory basis for the control mode in actual system.Based on the basis of theoretical analysis, the thesis decided to divided FKHB system into3layer structures:management, control layer and equipment layer. The management uses PC with Kingview to design monitoring picture, and the hardware of control layer chooses Siemens S7-300PLC and MM440converter. Such system’s structure improves the reliability and reduces costs, also increases flexibility. The Flow control uses PROFIBUS-DP to connect MM440; the sequence control of storage tanks uses GRAPH; the temperature control of Thin-Film Evaporation chooses the Fuzzy-PID and the language used the high level language SCL for complex function in STEP7.At present, the whole control system has been put into operation, and the system operation is stable and reliable on the basis of operation result, and greatly reduces human labor. The distillation temperature of waste oil is more accurate and smooth than earlier, and the control improves the product quality and rate, creates benefit for enterprise, and also gives strong support for the promotion of the equipment.