(583c) CFD-DEM Simulations of a Gas-Solid Vortex Reactor

The constant search for innovation, both in process and reactor design poses many challenges in the years to come. Process intensification plays a huge part in the selection of novel reactor designs. The gas-solid vortex reactor (GSVR) is an ideal candidate for the introduction of process intensification methods to heterogeneously catalyzed processes (e.g., fluid catalytic cracking, oxidative coupling of methane) and pyrolysis processes (e.g., biomass, plastic waste) that are currently performed in packed bed or gravitationally fluidized bed reactors. By making clever use of the centrifugal force, a rotating catalyst bed is obtained allowing for higher gas-solid slip velocities and gas throughputs compared to gravitationally fluidized beds. Whereas the residence time distribution inside a fluidized bed reactor is fairly broad, it is much more narrow inside the GSVR.

A detailed four-way coupled CFD-DEM model was constructed with the open-source package CFDEMcoupling, which couples the CFD package OpenFOAM with the DEM solver LIGGGHTS. Extensive hydrodynamic validation was performed both in a fluidized bed and a GSVR geometry on minimum fluidization velocities and particle velocity profiles, showing good agreement with experimental PIV data. A parameter study was performed to determine the influence of different particle properties (i.e., density and size) on the hydrodynamic behavior in the GSVR. Next to particle properties, the effect of solids loading on bed stability was investigated. These CFD-DEM simulations provide important insights in the bed hydrodynamics, which cannot be obtained using experimental PIV measurements, since the latter only provide information about the bed near the optically accessible end walls.

Finally, an energy model was incorporated and validated to accurately characterize gas-solid heat transfer in this intensified reactor type. Heating and cooling curves were constructed of particles in both a fluidized bed and GSVR geometry, proving the excellent heat transfer characteristics of the GSVR.