(648i) Meso-Scale Modeling in Gas-Solid Fluidizaton and Applications in Catalytic Fluidized Beds

Gas-solid fluidization manifests meso-scale dynamic structures spanning a wide range of length and time scales. When the gas-solid catalytic reactions are involved, more complex phenomena emerges such as the change of physical properties, heat transfer between gaseous phase and solid phase, thus posing bigger challenges for modeling. As the meso-scale is the most information scale to understand the gas-solid fluidization which the conventional two-fluid model (TFM) without meso-scale modeling may be inadequate to resolve even using extremely fine grids, this study presents the meso-scale modeling for the gas-solid reactive flows including development of structure-dependent drag model considering the change of physical properties, heat transfer model considering the effects of meso-scale structures, etc. Then, applications in the novel fluid catalytic cracking (FCC) reactor and the methanol-to-olefins (MTO) process are discussed. The results prove that the meso-scale modeling plays a remarkable role in improving predictions of hydrodynamic behaviors and overall reaction rate, while the selectivity of olefins is not accurately predicted. The future work will explore to a better coupling between the chemical kinetics and flow structures.