Design And Research Of Fluidized Bed Control System For Silica Drying

Silica（SiO₂-nH₂O）,an environmentally friendly and excellent performance additive,can be used in a wide range of applications.It is used as a carrier or diluent in pesticides and high-efficiency spray fertilizers,as an additive in feedstuffs,and as a reinforcing agent in rubber.Thanks to the rapid development of pesticide industry,feed industry,tire manufacturing industry and other fields,China’s demand for silica has occupied 40% of the Asian silica market.How to improve the automation level of silica drying to meet the urgent needs of many fields such as agriculture is of practical significance in promoting the improvement of pesticide carriers,upgrading of feed,deepening technology upgrading,and promoting the development of pesticide industry and animal husbandry in China.In order to improve the current situation that the control system of domestic drying industry is not perfect,it is necessary to continuously improve and perfect the control system of drying fluidized bed according to the production data of drying plant site.In order to meet the needs of the new situation,this paper takes silica drying fluidized bed as the research object,combines production data,conventional PID and fuzzy control theory,and proposes a silica drying control scheme based on fuzzy adaptive PID control.The main research work is as follows.（1）By consulting domestic and foreign literature and engineering examples of drying fluidized bed,analyzing the composition,drying process and experimental data of drying fluidized bed,studying the dynamic and static characteristics of fluidized bed,the design requirements of drying control system were proposed.（2）By analyzing the multi-variable coupling characteristics between fluidized bed parameters,the whole control system was divided into moisture control system and pressure control system,and the control closed-loop circuits of the two subsystems were designed.（3）Using fuzzy control theory and MATLAB fuzzy logic tools,we designed a fuzzy adaptive PID controller applicable to the silica drying control system,and built a simulation model to compare the control effect with the conventional PID controller,and achieved the purpose of adjusting the parameters of the controlled object by continuously optimizing the controller.（4）According to the system requirements,the hardware was selected and calibrated,the HMI was configured,the controller was programmed,and the fluidized bed control system for drying silica was built.After continuous debugging and optimization,the pressure in the fluidized bed was stabilized within the normal operation range of-40Pa～-80Pa,the error between the moisture of the system-dried silica and the target moisture was controlled within±0.5%.Experimental results showed that the fuzzy adaptive PID-based fluidized bed control system for silica drying improves the fluidized bed drying efficiency and meets the precise moisture requirements of the product,which can be promoted and used in the process with similar characteristics.