Computational Fluid Dynamics for Fixed Bed Reactor Design

Abstract

Flow, heat, and mass transfer in fixed beds of catalyst particles are complex phenomena and, when combined with catalytic reactions, are multiscale in both time and space; therefore, advanced computational techniques are being applied to fixed bed modeling to an ever-greater extent. The fast-growing literature on the use of computational fluid dynamics (CFD) in fixed bed design reflects the rapid development of this subfield of reactor modeling. We identify recent trends and research directions in which successful methodology has been established, for example, in computer generation of packings of complex particles, and where more work is needed, for example, in the meshing of nonsphere packings and the simulation of industrial-size packed tubes. Development of fixed bed reactor models, by either using CFD directly or obtaining insight, closures, and parameters for engineering models from simulations, will increase confidence in using these methods for design along with, or instead of, expensive pilot-scale experiments.

Young Scientists – Juniorprofessor Gregor D. Wehinger stellt sich vor

“…Da mithilfe von PRCFD Festbettreaktoren detailliert modelliert werden können, stellt sich die Frage, welcher Detailgrad die Kinetik aufweisen soll. Formalkinetiken, Langmuir-Hinshelwood-als auch mikrokinetische Ansätze wurden in der Literatur mit PRCFD angewendet und diskutiert, s. dazu [14]. Unsere bisherigen Studien haben gezeigt, dass es möglich ist, Mikrokinetiken in PRCFD von Festbettreaktoren einzuführen [2].…”

Conventional anddata‐drivenmodeling of filtered drag, heat transfer, and reaction rate ingas–particleflows

“…Heat transfer and chemical reactions in these processes introduce a substantial complexity due to the presence of inhomogeneous flow structures 1 . A deep understanding of the complex flow, transport, and reaction behavior is of great importance for optimal design and scale‐up of processing devices 2–4 . To this end, numerous empirical correlations have been proposed to describe interphase heat, mass, and momentum transport for fluid–solid flows.…”

“…However, the empirical correlations cannot provide the specific spatial distribution information of key transfer parameters 1 . Over the last decades, computational fluid dynamics (CFD) has gained much attention and is increasingly used as a tool for studying the details of the local flow, transport, and reactions 4 . Particularly, the information from highly resolved direct numerical simulation (DNS) of fluid‐particle systems can be used for developing microscopic interphase exchange closures used in the unresolved models, such as the two‐fluid model (TFM) and CFD–discrete element method (CFD–DEM).…”

Influence of Macroscopic Wall Structures on the Fluid Flow and Heat Transfer in Fixed Bed Reactors with Small Tube to Particle Diameter Ratio

“…• Particle-resolved computational fluid dynamics (CFD), where each pellet and the fluid, including the interstices between the particles are fully spatially resolved, and Navier-Stokes equations are solved. A detailed description of this modeling approach is presented in the comprehensive review articles by Dixon [6], Jurtz et al [7] and Dixon and Partopour [8].…”