Reaction behavior in packed bed considering bed structure and reaction properties of particles

To decrease the reducing agent ratio in the blast furnace, various measures such as mixed charging are being pursued. Coke mixed charging is considered to improve permeability in the cohesive zone and the reducing behavior of ore particles. Conventionally, these researches were frequently carried out with a small packed bed. However, the information obtained by these experiments was based on a macroscopic analysis. In the present research, a DEM-CFD model developed by the authors was applied to precisely analyze reaction behavior under various packed bed structures, such as that with coke mixing. Moreover, the effect of high reactivity coke on the reduction rate of ore was examined using this model. According to the results, coke mixed charging has little influence on the reduction rate. When high reactivity coke was charged to the ore layer, the particle temperature decreased due to the endothermic reaction by high reactivity coke. Accordingly, the reduction rate of the ore particles was suppressed as a result of the temperature change. This phenomenon was relatively noticeable in the packed bed structure with high reactivity coke set up in the lower part.