Numerical Simulation of Granular Phase Flow Behavior and Heat Transfer Characteristics in an Industrial-Scale Rotary Cooler

In a calcined clay rotary cooler, the flow behavior and heat transfer characteristics of the granular bed are key factors determining the cooling efficiency. In this study, an Euler–Euler multiphase model coupled with the kinetic theory of granular flow (KTGF) was used to simulate the granular bed flow and heat transfer in a rotating drum of a rotary cooler. Unlike conventional large-particle beds, the 11 μm calcined clay particles interact more strongly with the gas phase, resulting in stratification and fluidization in the fine-particle bed. The effects of rotational speed, baffle configuration, and number of baffles on the flow and heat transfer behavior of the calcined clay granular bed were investigated. The results show that L-shaped baffles provide superior cooling, achieving a granular bed temperature and heat transfer coefficient (HTC) of 656.88 K and 151.15 W/(m2·K), respectively. At 2 rpm, the maximum temperature decrement and HTC increment are 5.73 K and 46.30 W/(m2·K), whereas excessive rotational speeds intensify bed fluidization. Additionally, increasing the number of L-shaped baffles has limited influence on expanding the fluidized region. With 12 L-shaped baffles, the temperature decrement peaks at 2.86 K and the HTC increment reaches a relatively high 33.27 W/(m2·K). This study provides a theoretical basis for the design and optimization of industrial-scale rotary cooling equipment for fine-particle beds.