Characteristics of solid flow and stress distribution including asymmetric phenomena in blast furnace analyzed by discrete element method

Since the solid flow in blast furnace is composed of each particle motion, the discontinuous phenomena of burden descending can be occasionally observed. Understanding of the solid flow is important for blast furnace operation. Discrete Element Method (DEM) can offer the behavior for each particle of burden in the furnace. Three dimensional analysis of solid motion containing the ununiform region became possible with using DEM. In the present study, a blast furnace of 2000 m³ inner volume with 16 tuyeres was taken as the object for the simulation. Firstly, the stream line of solid, velocity variation and stress field in blast furnace were simultaneously analyzed by using the characteristic of DEM on each particle movement. Especially, the transient behavior on velocity and stress distribution during charging and slipping were calculated. The fundamental characteristics of burden descending became clear. Secondly, this study has focused on the asymmetric phenomena in the blast furnace on the basis of the above results. In this calculation, number of active tuyere was intentionally varied. The stress network showed the remarkable change in this case. Moreover, it was found that many local slips between particles were distributed in the bosh and they concentrated on the region nearby the active raceway due to the weakened stress. The stress network is closely related the particle velocity distribution. The consumption rate of coke in the tuyere significantly affected on the circumferential uniformity. Totally, the discontinuous burden descending and the characteristic of particle movement were essentially understood.