Experimental and DEM analysis of transverse particle motion in a rotary drum with segment internals

Rotary kilns are essential for thermal and mechanical treatment of various bulk materials in different industries. They enable high throughput rates, continuous mixing and controlled process conditions. Heat transfer is enhanced through installation of internals often leading to particle abrasion and dust formation. To address this issue, a new internals design featuring a cross section has been developed, dividing it into several smaller, separate segments. This design increases the particle-wall and free bed interfaces which improves the heat transfer while reducing the mechanical stress on the particles. Experiments were conducted in rotary drums with diameters of 300 mm and 500 mm to analyze the particle motion. Glass and polypropylene beads with particle diameters ranging from 2 mm to 4 mm were used as test materials. A parameter study was performed for various filling degrees (5 % – 30 %) and rotational speeds (0.5–8 rpm). Additionally, the motion behavior was simulated using the discrete element method (DEM) and validated against experimental data. This approach enabled a numerical description of particle interactions, particle velocities and heat transfer-relevant surface areas. These results show the potential of employing segment internals in rotary kilns for the gentle and efficient thermal treatment of bulk materials.