DESIGN AND IMPLEMENTATION OF INTELLIGENT INTEGRATED MEASURING AND CONTROLLING SYSTEM FOR SUGAR CANE CRYSTALLIZATION PROCESS

The deficiency in existing sugar cane crystallization automatic control system is difficult to measure some key parameters on line, such as mother liquor supersaturation, mother liquor purity, crystal content and crystal size distribution. Controlling brix with PID can only reflect the massecuite concentration of sugar cane crystallization process, but it is hard to guarantee the crystal quality. During crystallization process, change of mother liquor purity will affect the crystallization rate and supersaturation. The less mother liquor purity in the final stage is, the better absorption of crystals have. Crystal size distribution, including mean area (MA) and coefficient of variation (CV), influences the quantity and quality of crystals. In order to produce sucrose which has uniform size and small coefficient of variation, it's necessary to study the law of crystal size for sugar cane crystallization. According to the difficulties in measuring some key parameters, an intelligent integrated measuring and controlling system is researched by this paper. The overall structure of this system is designed at first, and also the monitoring system of host computer is developed. Combining with data-driven modeling and hybrid modeling method, the intelligent soft-sensor component for sugar cane crystallization process is implemented. This system realizes automatic monitoring of sugar cane crystallization process, which includes on-line measurement of mother liquor supersaturation, mother liquor purity, crystal content and crystal size distribution (CSD). Experimental results show that this designed intelligent integrated measuring and controlling system for sugar cane crystallization process has not only achieved great on-line prediction for immeasurable parameters, but also has good openness and scalability, which can provide complete parameter detection for the implementation of sugar cane crystallization automatic control system.