Multi-Scale Simulation: From Particle Resolved Fixed Bed Simulation to Multi-Tubular Reactor Design

Packed bed reactors are one of the working horses in the chemical and process industry. They are used amongst others for highly exothermic or endothermic catalytic reactions like (partial-)oxidation or (dry, steam) reformation of Hydrocarbons, which is typically done in multi-tubular reactors. These types or reactor are used since several decades but there is still room for improvement of the performance of these reactors and rigorous simulations can help here to achieve desired goals with lower upfront invest. Recent advances in modeling particle-resolved packed beds [1,2,3] allows a detailed inside in the flow, species and temperature distribution in the beds and therefore also into the conversion of the surface reactions. Based on these simulations, model parameters for simplified 1D-models can be estimated [4]. These simplified models can then be used to calculated multi-tubular reactors, either by running a computationally expensive simulation with resolved tubes or by coupling the CFD simulation to an advanced process simulation tool like gPROMS. In the later case, the flow non-uniformity as well as certain flow properties like coolant velocity and temperature is taken from the CFD simulations, while on the process modeling side heat transfer and reactions in the packed bed are calculated based on the simplified 1D models. This modeling approach is fully 2-way coupled and highly efficient in terms of accuracy and especially run-time and it can be embedded into a flow sheet simulation.

In this contribution we will show the whole simulation process and how the different steps intertwine with each other starting from the detailed particle resolved simulation all the way down to the flow sheet simulation. The benefit of this approach with be demonstrated based on several examples.

1. Eppinger, et al.; DEM-CFD simulations of fixed bed reactors with small tube to particle diameter ratios, https://doi.org/10.1016/j.cej.2010.10.053
2. D. Wehinger et al.: Detailed numerical simulations of catalytic fixed-bed reactors: Heterogeneous dry reforming of methane, https://doi.org/10.1016/j.ces.2014.09.007
3. Jurtz et al.: Advances in fixed-bed reactor modeling using particle-resolved computational fluid dynamics (CFD), https://doi.org/10.1515/revce-2017-0059
4. Jurtz et al.: Determination of Effective Transport Parameters from Particle-Resolved CFD Simulations for a Simplified Fixed-Bed Reactor Modeling (65a), AIChE Spring Meeting 2019, New Orleans