The Study of the Process Dynamics and Control of a Continuous Stirred Tank Reactor Using a Partial Simulation Technique

Abstract

The problem was to analyse the stability and controllability of a continuous stirred tank reactor which was effecting an exothermic reaction. The approach chosen was a partial simulation technigue by which it was hoped to retain some of the real plant characteristics whilst eliminating some of the more undesirable aspects. [In this way it was anticipated that the gap between the completely theoretical approach and real plant analysis would be narrowed. The equipment. employed was a typical well stirred vessel which received a flow of water representing feed to the reactor. The vessel was cooled by water flowing through a coil which was situated in the vessel. Heat equal to that released from the exothermic reaction was generated by means of immersion heaters. The kinetics were simulated on an analogue computer which monitored the feed flowrate into the tank and also the temperature of the water within the tank. The computer was programmed with the idealised model of the process's material balance and by continually integrating this in real time it calculated the heat generation for the current value of temperature and concentration in the tank. This value was then transformed into real heat release in the vessel by means of immersion heaters through a servomechanisnm. The stability and controllability of the partially simulated stirred tank reactor was then investigated, the results being obtained in phase-plane portrait form. The control of the reaction temperature was effected by employing a standard feedback control loop in real plant hardware. The research showed that the partial simulation technique offered more versatility than real plant analysis whilst the outlay necessary to conduct the work was much reduced. When compared with complete simulation it was evident that the demand on computer space was much reduced yet more of the real system character was retained.