Chapter 4 - Flow Modeling of Trickle Beds

Abstract

With the current level of understanding, it is more advantageous to use a hierarchy of models coupled with key experimental findings to achieve practical benefits. This chapter, therefore, discusses different modeling approaches, which allow better quantitative understanding of the processes occurring in trickle bed reactors. A “unit cell” approach, or considering an assembly of a few particles, is very useful for obtaining quantitative insights into the flow structures and transport processes occurring in packed beds. This approach can also be extended to gas-liquid flow through packed beds using VOF (volume of fluid) models. Information obtained from these models can be used for developing appropriate closures for macroscopic models. The Eulerian-Eulerian approach is recommended for the modeling of macroscale flow processes in fixed bed as well as trickle bed reactors. The realistic representation of the characteristics of the fixed bed (porosity distribution, degree of anisotropy, and so on) is crucial for carrying out simulations for engineering applications. Most of the current work relies on empirical information and pressure drop data to calibrate computational flow models of fixed and trickle bed reactors. Such calibrated computational flow models will be useful for understanding issues related to maldistribution, channeling, formation of hot spots, etc. To realize process intensification and performance enhancement, accurate knowledge of the underlying flowfield in chemical reactors is essential.