|Title: CFD-Based Compartment Modeling of Continuous Polymer Reactors in Milli-Structured Apparatuses by Use of the Mean Age Theory.
|Written by: Schwarz, S.; Frey, T.; Hoffmann, M.; Grünewald, M.; Schlüter, M.
|in: <em>Industrial & Engineering Chemistry Research</em>. (2023).
Abstract: The transformation of energy-intensive batch processes for small-scale polymer specialties into more energy-efficient continuous processes is a challenging task due to the occurrence fouling. To determine safe operating windows, a proper reactor model is needed. Indeed, a computational fluid dynamics (CFD) can resolve potential fouling zones; however, the computational demand of a detailed CFD of entire reactors is in general uneconomical for parameter studies, transient problems, or complex reaction mechanisms such as polymerizations. Contrary, reduced basic reactor models, such as plug flow reactors, can be used for simulation studies of entire reactors due to their low computational demand but cannot resolve potential fouling zones. The compartment modeling approach offers a promising method to combine relevant fluid dynamics from CFD models with the simulation of complex reaction mechanisms. In this contribution, a compartment model of a 3 m milli-structured reactor for polymer synthesis is derived from a reduced CFD model. The computational CFD mesh of a section of the reactor is transformed into a cascade of continuously stirred tank reactors (CSTRs) by clustering the CFD cells based on the local mean age, allowing the spatial interpretation of fouling zones. The mean age theory is used to evaluate the fluid dynamics and mixing characteristics of the derived compartment model and compare it with the CFD. With a scale-up, the compartment model describes the entire residence time reactor and enables transient simulations and parameter studies with a significantly decreased computational demand. The compartment model is validated with experimental data for a catalytic polymerization process.