Self-Tuning Adaptive Control of a Fluidized Bed Chemical Reactor

Abstract

Abstract An application of self-tuning control to a fluidized bed reactor for ammoxydatlon of propylene to acrylonitrile is studied. The acrylonitrile is one of the main raw mateAial used for the fabrication of synthetic rubbers and fibres. The main reaction is highly exothermic. The highest yield of acrylonitrile occurs in temperature range of 480-510°C. Thecatalyst is very fragile at high temperature and does not resist to large and sudden temperature variations. The purpose of the control is to maintain the temperature of the reactor closeto a desired value [490°C] in order to facilitate the phenomenologlcal study (isothermal model building) is well as to avoid risks of destruction of the catalyst. The velocity of a ventilator whose.function is to carry away some, of the produced heat was considered as the control variable. The reactor has been interfaced with an Apple II micro-computer. The host programm used in the control is written in Pascal. Itcall external assembly language routines related to real time control such that : date acquisition routine, digital-analog converter routine, and the clock reading routine for sampling period. A simplified single input-single output model ofthe complex dynamics of the reactor was assumd. A constant trace algorithm is combined with an extented minimal variance controller including the set point action. The self-tuning controller gives improved control performance, compared to that achieved using proportional plus integral plusderivative (P.I.D.) control.