(481a) Modeling of Fluid-Solid Heat and Mass Transfer in Particle Resolved CFD Simulations of Catalytic Fixed Bed Reactors

In the chemical process industry, highly exothermic and endothermic, heterogeneously catalyzed gas phase reactions are commonly carried out in fixed bed reactors with small tube to particle diameter ratio. The varying structure of such fixed beds causes local effects on the flow field such as channeling or stagnation, which strongly influences transport phenomena and the reaction [1]. Therefore, particle resolved computational fluid dynamics (PRCFD) simulations, which consider every particle, seems to be the most promising approach for an accurate description of these reactors [2]. In this work a numerical stable and computationally efficient conjugated heat (CHT) and mass (CMT) transfer model is presented coupling the fluid flow through the packed bed with transport and reaction in the porous catalyst within the commercial CAE software Siemens Simcenter STAR-CCM+. The calculation scheme of the developed CHT and CMT model for coupling the fluid and solid domain is given in Figure 1.

The new approach is tested with the highly exothermic reaction of n-butane to maleic anhydride (MA) carried out in a packed bed of 100 ring shaped vanadium-phosphorus-oxide catalyst particles under industrial relevant process conditions. The catalytic reaction is implemented via heat and species sources determined with the reaction kinetic derived by Müller et al [3]. Figure 2 shows the results for the simulated temperature and n-butane partial pressure along a plane cut through the packed bed. In the next step the new method is applied to longer fixed beds and the results of these simulations are validated with temperature and concentration profile measurements from a sample port reactor.

References

[1] A. G. Dixon, M. Nijemeisland (2001) Ind. Chem. Res., 40 (23), 5246.

[2] N. Jurtz, M. Kraume, G. D. Wehinger (2017) Rev. Chem. Eng., 35 (2), 139-190.

[3] M. Müller et al. (2020) Ind. Eng. Chem. Res., 60 (1), 218-229.