Modeling and Simulation of a Multi Phase Semi-batch Reactor

Abstract: The operation of an industrial semi-batch reactor is modeled and the flow of one reactant is investigated. In the reactor a strongly exothermic polymerization reaction takes place followed by a slightly exothermic reaction, and the objective is to minimize the duration of the operation of the process. Various operational as well as quality and safety related constraints have to be met during the batch. The complete process model is derived from measurements, first principles, and reasoning about effects on molecular level. This work has been performed in cooperation between Akzo Nobel Functional Chemicals and Chalmers. We have increased the knowledge of one semi batch process and tried to improve the production of thickeners by modeling the production process with the aid of mathematics. A better understanding of the underlying principles including the chemical reaction heat, energy transfer and the control system has been gained. The process model is simulated using MATLAB and SIMULINK. The optimization is made through investigations of manually chosen EO profiles and simulations. Piecewise constant EO profiles with up to three constant plateaus and varying levels have been used. Simulations show that a 5 % increase in total batch time is possible, using a profile with two plateaus as in the original, but with 20 % higher levels and no delay. A 10 % shorter batch time than today is possible using a profile with three different plateau levels. However, in this a profile, a large portion of the EO is added prior to the wanted reaction temperature is reached, which may result in a worsened end product quality. In order to decide which profiles are acceptable, more research about the effect of the reaction temperature used on the end product quality is needed.

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