Improving the Mathematical Model of a Heterocatalytic Tube Reactor

Abstract

In recent decades the applicability and usefulness of mathematical models in the solution of many industrial problems have been shown. There are many cases when the correct answer can not be given because of the complexity of the problem however CFD approaches can be applied to dig deeper and improve the reliability of results. In this work the improvement of the first-principle model of a tubular fixed-bed reactor is shown applying COMSOL Multiphysics. Mathematical models of tubular fixed bed catalytic reactors to simulate their operation are well known and the formulation of such models is well documented. In most cases the aim of modeling is the development of the simpliest model which can be applied to solve the modeling task. However, nowadays these modeling problems can be more complicated and require more accurate models, e.g. in case of model based diagnostic systems, early detection systems. After the model with the adequate complexity was developed it must be solved with the necessary accuracy. In general, as the complexity of the model increases, so does the chance of encountering numerical difficulties. Our purpose is to apply the most appropriate software methodology to solve problems at each level of the model hierarchy, therefore a proccess model of an industrial heterocatalytic reactor has been extended with integrating transport processes on micro level. The idea is the integration of a model of a single catalyst pellet implemented in COMSOL Multiphysics into the steady-state process simulator of the reactor developed in MATLAB. The proposed approach makes possible to develop the model of a whole catalyst bed from the particle models. The first step to accomplish our purpose is the implementation of the pellet model in the applied CFD code. Then the pellet model can be integrated into the process simulator at the higher model hierarchy level.