Comprehensive CFD-TFM Simulation of Drying in Spouted Beds with Draft Tubes

In this article, simulation runs were conducted to predict the drying evolution of sand in conical spouted beds with a nonporous draft tube using the Eulerian-Eulerian approach. The simulation results were validated against experimental data reported in the literature, and good agreement was achieved. In addition, the effects of various operating and design parameters, such as superficial gas velocity, inlet air temperature, the draft tube's length and diameter, and the solid phase's initial moisture content on the sand drying, were carefully investigated. It was found that the operating temperature and superficial gas velocity are the most essential parameters for improving the drying process and reducing the drying time of the sand particles. In addition, the choice of drag model, restitution coefficient, and specularity coefficient were found to have no significant influence on the drying time of the solid phase. Moreover, increasing the particles' diameter and initial moisture content leads to longer drying times, whereas increasing the conical bed angle prolongs the drying time for the solid particles. On the other hand, increasing the nozzle diameter and entrance length decreases the drying time of the solid phase. Furthermore, reducing the diameter and length of the draft tube also decreased the drying time.