Application of models with different complexity for a stirred tank reactor

Abstract

Engineering problem solving such as process design, process optimization, safety analysis, etc.; relies widely on mathematical models of the process. Tosolve various engineering problems various models with different complexity are needed. A stirred tank reactor with a highly exothermic reaction is studied in this work, because in the modern chemical technologies mixing is one of the most important operations, and stirred reactors are widely used in industrial applications. The stirring system of a mixed tank is always an important aspect of the design, because the involved processes (such as reactions, heat and component transport) usually requireproper contact and homogeneity of the existing phases. For the suitable homogeneity the design and the size of the moving parts are also important problems. In certain situations attachment of static parts to a stirred tank (such as baffles) may havean important effect too. The primary goal of this study is to create models with different level of complexity and determine which model is the best suited for solving different engineering tasks such as process design, scale-up, or optimisation. etc. To determine which model fits best for a problem, mathematical models were created and compared to find out, how the information can be extracted from these models and be applied to solve engineering problems. Three types of models have been developed: perfectly mixed reactor model, compartment model, and Computational Fluid Dynamics (CFD) models withdifferent dimensions. The reaction of hydrogen peroxide with sodium thiosulphate in a continuously stirred tank reactor is analysed as a case study. The perfectly mixed vessel models and compartment models were solved in MATLAB/SIMULINK program package. The CFD models were implemented in COMSOL Multiphysics.