Waste heat recovery of blast furnace slag in moving bed: Influencing of structural parameters and operating parameters

Physical recovery of waste heat from blast furnace slag (BFS) by a moving bed is a promising solution. The heat recovery of BFS is mainly achieved through gas–solid heat exchange with cold air and solid–solid heat exchange with water in a moving bed. In this study, the heat transfer process of BFS particles with a particle size ranging from 0.5 mm to 3.0 mm in a rectangular, trapezoidal variable cross-section moving bed was analyzed numerically. The influence of structural parameters and operating parameters of variable cross-section moving beds on heat recovery of BFS was studied. The research found when the inclination angle of the moving bed was 50°, the cooling airspeed was 0.3 m·s⁻¹, and the discharge rate was 0.9 g·s⁻¹, it can not only satisfy the cooling of particles below 400 K, but also ensure that the cooling efficiency of the particles in the bed was higher than 92 %. In this working condition, the improvement of cooling effect and the suppression of reheating could be realized at the same time. Meanwhile, the impact caused by excessive airspeed was weakened, and so was wall wear and dust removal device complexity. The study also found that laying a water-cooled wall can reduce the area of the dead zone of heat exchange and the particle temperature in the dead zone and ensure that the discharge temperature was lower than 380 K.