The heat transfer characteristics of semi-molten wide sieving dilute phase particles between vertical heating surfaces

The high-temperature slag produced during the steelmaking process presents a significant opportunity for waste heat recovery and material utilization. Centrifugal granulation is acknowledged as an effective treatment method for managing this slag. However, the compact design of centrifugal granulation equipment poses a challenge in achieving the necessary cooling rates for high-temperature slag relying solely on gas-solid heat transfer within a confined space. This paper presents a physical model for the gas-solid two-phase interaction of an ultra-dilute high-temperature particle cluster and analyzes its heat exchange with vertical heating surfaces. The research indicates that radiative heat transfer is the primary mode of heat exchange between the particles and the heated surface, constituting more than 50 %. Moreover, heat is transferred from the particles through the air to the heated surface. Significantly, lowering the air inlet temperature and the particle velocity greatly improves the heat transfer performance and overall efficiency. Additionally, increasing the air flow rate can offset the decrease in contact thermal conductivity and radiative heat transfer that may occur due to increased spacing between the vertical tube bundle heating surfaces, thus promoting particle heat transfer. This study is crucial for guiding the improvement of heat transfer techniques for high-temperature molten particles in confined spaces.