Effect of vertical cooling furnace structure on hydrogen cooling behavior of oxidized pellets

Hydrogen cooling of hot oxidized pellets not only recovers the sensible heat of the pellets but also produces prereduced pellets, thereby reducing the energy load and reduction burden in subsequent smelting processes. This study investigates the hydrogen cooling process of high–temperature oxidized pellets in a vertical cooling furnace through numerical simulation, with a focus on the effects of key parameters—including bed height, shaft angle, and central baffle angle—on cooling efficiency, metallization rate, exergy efficiency, and gas utilization rate. A multiphase mathematical model is developed based on mass, momentum, and energy conservation equations, accounting for compressible gas flow, pellet reduction reactions, and heat transfer. The results show that increasing the bed height extends the residence time, which improves the metallization rate, exergy efficiency, and cooling gas utilization rate, with an optimal bed height of 5.62 m. A furnace angle of 157° promotes reaction uniformity and enhances process efficiency, while a central baffle angle of 134° optimizes gas distribution and reaction homogeneity. Under the optimal configuration, the process achieves a metallization rate of 32.55%, an exergy efficiency of 23.84%, and a cooling gas utilization rate of 27.56%.