Challenges in the Simulation of Drying in Fluid Bed Granulation

Fluid bed granulation is faced with a high level of complexity due to the simultaneous occurrence of agglomeration, breakage, and drying. These complexities should be thoroughly investigated through particle–particle, particle–droplet, and particle–fluid interactions to understand the process better. The present contribution focuses on the importance of drying and the associated challenges when modeling a granulation process. To do so, initially, we will present a summary of the numerical approaches, from micro-scale to macro-scale, used for the simulation of drying and agglomeration in fluid bed granulators. Depending on the modeled scale, each approach features several advantages and challenges. We classified the imposed challenges based on their contributions to the drying rate. Then, we critically scrutinized how these challenges have been addressed in the literature. Our review identifies some of the main challenges related to (i) the interaction of droplets with particles; (ii) the drying kinetics of granules and its dependence on agglomeration/breakage processes; as well as (iii) the determination of drying rates. Concerning the latter, specifically the surface area available for drying needs to be differentiated based on the state of the liquid in the granule: we propose to do this in the form of surface liquid, pore liquid, and the liquid bridging the primary particles

Selective CO2-Hydrogenation using a membrane reactor

We present a novel membrane reactor (MR) concept for CO2 -hydrogenation to methanol application, in which CO2 is supplied from a CO2 -rich gas stream via a membrane and is distributed along the catalytic packed bed, where it reacts with hydrogen over a CuO-ZnO/Al2O3 catalyst to produce methanol. The performance of the reactor was investigated using a set of two-fluid model simulations. The simulation results showed that the fine distribution of CO2 improved the selectivity of methanol production by a value of 6 % for the studied range of the operating conditions

Sustainable Process Design for Oxidative Coupling of Methane (OCM): Comprehensive Reactor Engineering via Computational Fluid Dynamics (CFD) Analysis of OCM Packed-Bed Membrane Reactors

The oxidative coupling of methane (OCM) reaction system was investigated in a packed-bed membrane reactor (PBMR) numerically via a comprehensive computational fluid dynamics (CFD) study. In this context, the complete set of momentum, mass, and energy balances were solved through finite-volume method in cylindrical coordinate system. The fractional-step method was utilized to decouple the reaction source terms from the convection-diffusion terms. The general observed trends for variation of the components’ concentrations along the bed were successfully explained by analyzing the rate of reactions. In this study, the effect of membrane thermal conductivity, and oxygen permeation were also examined which can affect the OCM reactor and process performance significantly. Finally, the dynamics behavior of the system was studied and by following the reaction rates and the shift of reactions along the catalytic-bed and with time, the reaction mechanisms were discerned. The results of the performed CFD simulation can be used as a baseline for a possible optimization approach for OCM reactor performance improvement