CFD simulation of multiphase flows in porous solid foam structures

Ceramic foam packings, due to their high porosity, high specific surface area and low pressure drop are promising alternatives for reactor internals used in chemical engineering processes. The applications of solid foam packings as burners and heat exchangers have been widely studied, but as catalyst carriers particularly for gas-liquid reaction systems solid foam behaviour is not yet well understood. Due to its highly porous nature, it is very tough to understand the influence of hydrodynamics on the process performance. [1] The goal of this work is to perform three-dimensional Computational Fluid Dynamics (3D CFD) simulations of the evolving gas-liquid flow patterns considering ceramic foams as column internals and to validate them with experimental X-ray tomographic data. It is noteworthy to mention that up to now no 3D CFD simulation has been performed considering ceramic foams as column internals in pilot-scale. On the other hand, a few simulation studies are available considering spherical particles as packings in trickle bed reactors. The trickle bed closures will be modified according to the ceramic foam specifications.

A two-phase Eulerian model is used considering the flow domain as porous body. The influence of the liquid and gas drag is added as external source terms to liquid and gas momentum equations separately. The drag force between the phases has been taken into account using the relative permeability approach, which was developed by Saez and Carbonell [2] for packed beds using capillary pressure and relative permeabilities of two-phase flows. First results from the single-phase pressure drop and the two-phase gas-liquid distribution will be presented.

[1] Calvo. S., Beugre. D., Crine. M., Leonard. A., Marchot. P., Toye. D., Phase distribution measurements in metallic foam packing using X-ray radiography and micro-tomography, Chemical Engineering and Processing, Vol. 48, pp. no. 1030–1039, (2009).
[2] Saez, A.E., Carbonell, R.G., Hydrodynamic Parameters for Gas-Liquid Cocurrent Flow in Packed Beds, AIChE Journal, Vol. 31, No.1, pp no. 52- 62, 1985.

Acknowledgement

This work was funded by the Helmholtz Association within the frame of the Helmholtz Energy Alliance "Energy Efficient Chemical Multiphase Processes".