AbstractIn 2006, Dixon et al. published the comprehensive review article entitled “Packed tubular reactor modeling and catalyst design using computational fluid dynamics.” More than one decade later, many researchers have contributed to novel insights, as well as a deeper understanding of the topic. Likewise, complexity has grown and new issues have arisen, for example, by coupling microkinetics with computational fluid dynamics (CFD). In this review article, the latest advances are summarized in the field of modeling fixed-bed reactors with particle-resolved CFD, i.e. a geometric resolution of every pellet in the bed. The current challenges of the detailed modeling are described, i.e. packing generation, meshing, and solving with an emphasis on coupling microkinetics with CFD. Applications of this detailed approach are discussed, i.e. fluid dynamics and pressure drop, dispersion, heat and mass transfer, as well as heterogeneous catalytic systems. Finally, conclusions and future prospects are presented.
Catalytic fixed-bed reactors with a low tube-to-particle diameter ratio are widely used in industrial applications. The heterogeneous packing morphology in this reactor type causes local flow phenomena that significantly affect the reactor performance.Particle-resolved computational fluid dynamics has become a predictive numerical method to analyze the flow, temperature, and species field, as well as local reaction rates spatially and may, therefore, be used as a design tool to develop new improved catalyst shapes. Most validation studies which have been presented in the past were limited to simple particle shapes. More complex catalyst shapes are supposed to increase the reactor performance. A workflow for the simulation of fixed-bed reactors filled with various industrially relevant complex particle shapes is presented and validated against experimental data in terms of bed voidage and pressure drop. Industrially relevant loading strategies are numerically replicated and their impact on particle orientation and bed voidage is investigated.
K E Y W O R D Sbed voidage, fixed-bed reactor, numerical modeling, particle orientation, pressure drop
The impact of the static friction coefficient, the initial particle orientation, and the particle height-to-diameter ratio on the bed voidage of random packings with a low tube-to-particle diameter ratio is investigated for spherical and cylindrical particles using the discrete element method. Based on the numerical results a correlation is proposed to predict the bed voidage as a function of the static friction coefficient and the tube-to-particle diameter ratio for spheres, equilateral and non-equilateral cylinders. This correlation is extended for the use of hollow cylinders.
The experimental accessibility of disperse systems often is a critical factor when it comes to the development of modeling approaches that intend to converge towards an exact solution. Often, integral or pseudo‐homogeneous values are used to reduce the complexity of the system, but a detailed single particle or interface analysis is crucial to understand relevant effects that also affect the swarm behavior. A high number of experimental techniques with respective limitations and advantages is available to quantify these effects. In this work, an overview on measurement techniques for momentum, heat and mass transfer in particle swarms as well as for the particle size distribution and interface characterization is provided. The industrial applicability is addressed by pointing out the vicinity to the process and the costs of different measurement techniques.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.