With increase in pulverized coal injection rate to blast furnace, renewal behavior of deadman has been attracting much interests. This paper focuses on the renewal rate of the deadman induced by the sink-float motion of hearth coke bed, and it is discussed through cold-model experiments using half-cut model of blast furnace. Trajectories of packed particles in the deadman zone are converted into the transient velocity field, and further to the distribution of time required for particle transferring to the raceway zone. With this distribution the renewal rate of the deadman is quantitatively discussed. As the results, it is revealed that increase in the amount of accumulated water in the hearth, shallower hearth depth, and increase in gas flow rate make the discharging time of particles in the deadman zone shorter, and this tendency is explained by the height of sink-float motion of the hearth packed bed. About ten percent of particles that are discharged from the raceway passes through the deadman zone in the standard condition of this study. The particle movement induced by the sink-float motion of hearth packed bed is indispensable mechanism in the evaluation of deadman renewal.
- Blast furnace