(587d) Effect of Process Fines on Particle Heat Transfer and Temperature Uniformity in a Rotary Drum

The optimization of processes and reduction of energy waste are two big elements in many different industries and applications. The material properties as well as the equipment design will strongly influence operations and the ultimate quality of a product. In general, granular materials are present in different types of industries, from pharmaceuticals to catalysts, where rotary drums are used for different steps of the process, such as calcination and/or drying. Particularly in those cases, the processing of granular materials can generate a considerable number of fines that can affect the heating uniformity of those materials and consequently the final quality of the product. Therefore, it is important to understand how the presence of fines can influence heat transfer and flow of particles in a rotary drum. For this reason, this study focuses on incorporating fines to Discrete Element Method (DEM) simulations in order to obtain heating times that can be correlated to different industrial operations for predictability. In this work, different amounts and sizes of fines were considered. In all cases tested, it has been observed that fines act as a heat transfer medium between the drum wall and the particles, significantly improving heat transfer. Additionally, the presence of fines was also studied for different flow regimes which were achieved varying the wall friction coefficient of the drum. For all the static frictions tested, the addition of fines resulted in lower heating times than the particles alone. Finally, we have also considered the influence of one baffle in the flow and heating behavior of a bed of particles with fines in a rotary drum. Consistent with previous results for a bed with no fines, the addition of the baffle showed considerable improvement on heat transfer when operating in the slipping regime (low static frictions). Thus, this work aims to provide useful information on how the presence of process fines can influence heating behavior for different flow regimes in a rotary drum with and without baffles.