Chemical Engineering & Technology, Vol.34, No.7, 1076-1084, 2011
Moisture Distribution in Fluidized Beds with Liquid Injection
Coupled discrete element method-computational fluid dynamics (DEM-CFD) simulations have been performed to study the fluid and particle dynamics in a fluidized-bed granulator on the scale of individual particles. Simulation of the gas and particle dynamics is combined with heat and mass transfer mechanisms, as the moisture distribution is a key parameter for the functionality of a fluidized-bed spray granulator. The model allows monitoring the moisture content and temperature of each individual particle as well as the temperature and humidity of the surrounding gas phase. A novel modeling approach is presented to describe the process dynamics of a fluidized bed in full detail for a reference time interval using coupled DEM-CFD simulations. The motion profile of gas and particles is extrapolated to larger time scales and used for the calculation of heat and mass transfer. Through this multiscale approach, a step forward is taken towards a physically based description of the microprocesses in granulation.