Integrating CFD Methods in Packed Bed Reactor Design

Design of packed bed reactors is a challenging proposition. Experimental work to investigate the kinetics, heat transfer and fluid flow is inseparable part of the design process. A reliable design may need a lot of trial and error. Model based design approaches have been used to assist in this design process. They often involve simplifications such as assumption of plug flow or uniform porosity. Numerical modeling (CFD) has been also used to investigate some intangible aspects such as the hydrodynamics of this process by resolving particle scale geometries. Therefore such numerical simulations are themselves time consuming and cumbersome due to the intricate geometry and meshing requirements. Recent advances in the field of discrete element modeling (DEM) have made the feasibility of CFD simulation of hydrodynamics somewhat less cumbersome. A collaborative approach of numerical and experimental investigation can help a researcher achieve final goals of design lot quickly.

This presentation will cover the DEM based approach to resolved CFD modeling of packed beds. A few validation cases will also be presented. A lot remains to be done in the future, especially in the G-L flows in packed beds. Some of the challenges of such simulations will be discussed.

One of the unique benefits of such spatially resolved simulations is the detailed insight into packed bed reactors. E.g. the local velocity may be analyzed which shows locally a superelevation of up to 10 and zones with stagnant or backflow can be detected. Based on these findings an efficient optimization can be done.