Cold experiment investigation of nozzle height effect on the centrifugal granulation performance for heat recovery of metallurgical slag

Centrifugal granulation is a promising technology for recovering waste heat from metallurgical slag. While previous studies have focused on flow behavior over the atomizer surface, the influence of the fluid landing process on granulation mode transition and particle size distribution remains understudied. In this work, the centrifugal granulation process of water was visualized experimentally, with a focus on the effects of the nozzle height on granulation performance and droplet size distribution. The results show that with the nozzle height increased from 50 to 350 mm, the granulation mode gradually transformed from direct droplet formation to film formation, the average particle diameter gradually increased from 0.858 to 1.175 mm, and the size distribution gradually narrowed to a large size range. Furthermore, the effects of the nozzle height on critical flow rate and critical speed were investigated, revealing that higher nozzle positions reduce the critical flow rate but increase the critical speed. Finally, a dimensionless correlation equation was developed to predict the average particle size.