Computational Fluid Dynamics (CFD) Modeling of Swirling Flows in Industrial Counter-Current Spray-Drying Towers under Fouling Conditions

This work presents a novel procedure to predict the airflow pattern under different levels of deposition and Reynolds numbers for swirling-flow industrial-scale spray-drying towers. It improves the accuracy in the prediction of both the hydrodynamics and the effect of the deposition. Initially, steady-state and transient simulations are compared, showing that the model can be reduced to steady state for a certain mesh size. The computational fluid dynamics (CFD) model is later calibrated using the experimental swirl intensity values under different levels of deposits that have reached a dynamic equilibrium. The model then is validated for different Reynolds numbers of operation. Finally, the validated model is applied to examine the vortex behavior and evaluate the effect of the tower radius reduction. A limit of operation is found for low Reynolds numbers, in terms of stability, and it is observed that the momentum cannot be only modeled with the radius reduction.