Lumped modeling of bubbling fluidized beds for high‐temperature processes

Abstract

Bubbling fluidized beds (BFBs) have been a source of study for multiple decades. Among other applications, they can be used as scalable reactors for the conversion of biomass and waste resources to fuels. Several experimental and computational studies have been devoted to correlating the interplay of hydrodynamics and heat and mass transfer in fluidized beds. Despite the existence of several direct correlations for full‐scale reactors, these are typically only applicable to cylindrical reactor geometries, fluidized through a homogeneous gas distributor plate at the bottom. Detailed Computational Fluid Dynamics models could, in theory, handle more complex geometries, but are still computationally too expensive for industrial‐scale equipment. Therefore, there is a need for relatively fast models that enable researchers to estimate performance parameters with reasonable accuracy for non‐standard fluidized‐bed geometries. An important role is played by so‐called lumped models, in which the various interactions between the transport phenomena are explicitly described. Although lumping is not a new concept in the literature—various authors have applied lumping for hydrodynamics and heat transfer in the past—it is not immediately clear how different kinds of lumping could be used for more complex designs for high‐temperature processes. Here, we discuss the various lumped models available in the literature for fluidized‐bed reactors and critically analyze the developments necessary to apply them to high‐temperature processes.