Temperature control with fuzzy control of a semi-batch styrene polymerization reactor

The polymer production increases continuously in the world. Polymer production rate describes as million tones in a year. This amount has increased with using plastic or composite materials having desired features instead of metals. In the polymerization, main aim is the achievement of desired quality product. Due to, polymerization reactions are exothermic, large amount of heat appears and it causes big problems in industry. The quality of polymer depends on conditions of polymerization reaction (temperature, initiator, ect.), and temperature of reactor must be controlled very well.In this study, polymerization of styrene in a jacketed semi-batch reactor was examined. In the semi-batch reactor, free radical polymerization of styrene was carried out and polymer production with desired quality (conversion and number of average molecular weight) was aimed. In this study, genetic algorithm (GA) which is an optimization method was researched before experimental study, and Fortran programme was developed and used for theoretical results. The fitness function for GA was chosen as the integral of the absolute value of error, IAE. So, for fuzzy control which was chosen as the control method in this study, membership functions and relation matrix which provide the best control were obtained. Then, experimental studies with obtained fuzzy parameters were carried out. In experimental studies, styrene and toluene mixture was fed continuously to the reactor and the initiator benzoyl peroxide was solved in toluene and was thrown at one time. In experimental studies, reactor inside temperature was studied, and the desired set point was maintained with fuzzy control method. During the experiments, the concentration and molecular weight of polymer were measured analytically by taking samples. Then, these measured values were compared with desired values. As a result, GA with fuzzy control is a good way to control the temperature of semi-batch styrene polymerization reactor. It is seen that experimental monomer conversion values are higher than the theoretical values, and viscosity average molecular weights which were obtained experimentally are acceptable when compared with numerical average molecular weights.Key Words : Genetic Algorithm, Fuzzy Control, Semi-batchpolymerization reactors