Numerical study on heat transfer of blast furnace slag particles in a countercurrent cyclone heat exchanger

In dry centrifugal granulation of blast furnace slag with waste heat recovery, the heat exchange efficiency between high-temperature slag particles and cold air directly determines waste heat recovery performance. However, the heat transfer characteristics of slag particles in complex flow fields remain unclear. This study employs numerical simulation to investigate the gas–solid two-phase flow and heat exchange behavior of slag particles in a countercurrent cyclone heat exchanger. The effects of heat exchanger height, number of swirl vane turns, number of swirl vanes, and channel width on heat exchange performance are systematically examined. Results indicate that appropriately increasing these structural parameters enhances air outlet temperature and waste heat recovery efficiency. Under optimized conditions, the overall waste heat recovery efficiency of particle groups reaches 80.4%. The maximum deviation between experimental and numerical results is within 2%, demonstrating the reliability of the numerical model. This study provides a theoretical basis for structural optimization of countercurrent cyclone heat exchangers in blast furnace slag waste heat recovery.