Certain studies on sample time for a predictive fuzzy logic controller through real time implementation of phenol-formaldehyde manufacturing

摘要

In polymer manufacturing industries, the automation and control of chemical process incorporating techniques of fuzzy control neural networks, and expert systems had lead to a more secured and stable operation. A sudden and unpredictable heat is often produced by the nonlinear exothermal reaction when phenol and formaldehyde are mixed together. Therefore, the polymerization process has to be controlled with a high level of precision in order to avoid temperature run-away. This paper proposes a design methodology for a sensor based process control system. The duration of ON and OFF time of certain relays are the parameters to be controlled in order to keep the exothermic reaction under control The universe of discourse for the output of the FLC system is the sample time that assigned to the relays where maximum time for heater or valve can be turned on before the next action is applied This paper discusses a detailed real time implementation of the exothermal process control using Matlab-fuzzy logic toolbox. An enhanced predictive FLC structure is developed and compared to a predictive FLC control structure. The obtained practical results thus ensure that the predictive FLC can be enhanced by modifying the rules and the membership Junctions of the universe of discourse, which is proved to be better in controlling the reaction temperature.