Modelling of Chemical Reactors: From Systemic Approach to Compartmental Modelling

Abstract

Abstract To take into account the impact of hydrodynamics on their behavior, chemical reactors are traditionally modeled as an association of smaller ideal reactors: perfectly stirred or plug flow reactors. This modeling is mainly based on the reactor hydrodynamics but sometimes also on phenomena governing the considered process such as heat or mass transfer or chemical reaction. The approaches encountered in the literature start from the most basic one in which the whole reactor is considered as an ideal reactor, up to a very fine discretization using Computational Fluid Dynamics (CFD). In between, the reactor can be described as an association of a small number of ideal reactors: this is the systemic approach. Another intermediate approach has also been recently developed: the compartmental method, where all compartments are assumed to be perfectly mixed. In the compartment method, the compartment number is significantly more important than in the systemic approach - but lower than for CFD. Furthermore, these compartments are chosen to be relevant regarding their position in space as opposed to systemic models in which, in most of cases, only the global physical behavior is taken into account. Compared to CFD, compartment models are less computationally demanding while taking into account the most important flow features. The present review describes the different types of modeling commonly used in chemical reaction engineering during the last 60 years from the systemic approach to CFD, with a focus on the attractive compartmental modelling. In particular, the methodologies encountered to determine the compartment structure are detailed, as well as the different possibilities to determine the turbulent fluxes between compartments.