dc.description.abstract | This study uses the Discrete Element Method (DEM) to simulate the particle flow behavior in the hopper of a blast furnace. The objectives are to analyze the particle distribution in the hopper during the material charging process in a bell-less charging system, as well as measure the mass flow rate and the volume fraction of different materials during discharge. To achieve these goals, firstly we measured the physical properties of materials used in the blast furnace including coke, lump ore, sinter, pellet, and hot briquetted iron (HBI), etc., through the experiments. The properties are the angle of repose, bulk density, friction coefficient, and restitution coefficient of the materials. The properties such as the angle of repose and bulk density, created in DEM were also calibrated and verified by the experimental results. After the calibration of particle properties, the materials were charged into the hopper to simulate the particle flow behavior.
The geometry for the DEM simulation is on the basis of the hopper on the top of the blast furnace at China Steel Corporation. The effect of installing and not installing a stone box inside the hopper on the particle flow behavior was investigated. The simulation results show that the size segregation of particles inside the hopper with a stone box for the buffer was mitigated. In the simulation, the coke charging into the hopper is used to study the difference between whether there is a stone box or not. The simulation results show that the size segregation in the hopper can be reduced by installing the stone box. Furthermore, the study investigates the charging and discharging differences between the left and right hopper. It is found that the charging position of the conveyor belt at the top is asymmetric to the center axis of the dual hopper. This leads to the leftward deviation of the burden flow, resulting in a higher flow velocity in the left hopper compared to the right hopper. So more large particles gather on the wall of the right hopper, and the particle size segregation of the right hopper is more severe than that of the left hopper. In the three sets of simulations in this study, the average mass flow rate of discharge from the right hopper was higher than that of the left hopper.
In the simulation of the iron-bearing material being charged into the hopper, using sinter and HBI, the sequence in which HBI particles are filled into the hopper is varied. Since HBI particles are larger in size compared to other burdens, it is important to study whether their charging sequence affects the mass flow rate during discharge. The concern is that if particle arching occurs, it could significantly impact the Ironmaking process. If HBI particles are initially charged into the hopper, arching occurs during discharge. However, no arching occurred when charging HBI particles into the hopper in the middle and final stage, and compared to the results of charging HBI particles during the final stage, the simulation with HBI particles charged during the middle stage showed a more stable mass flow rate during discharge. | en_US |