Fig. 21. Distribution of mass of collected particles in the sampling boxes when three kinds of particles were examined under 51°.

The objective of this paper is to analyze the particle behavior at a bell-less top of blast furnace by using Discrete Element Method. The effect of chute angle on the flowing behavior or the particle segregation was discussed. The particles in the chute are centrifuged by the chute rotation with moving toward the outlet. The most of the smallest particles are pressed up against the chute side wall, while the larger ones stay at the outside of clustered particles due to the particle size segregation. The specific charged mass at charging area increases with increasing the number of charges, and the distribution of charged mass spreads toward the center of blast furnace, because the particles slide downward along with the slope of heap. The coke particles are pressed toward the center of blast furnace by the subsequently charged sintered ore particles with increasing the number of charges. The large collapse of coke layer is seen after 16 times charging under 36.9°and 43.1°in chute angle. It is found that the chute angle affects not only the particle segregation but also the collapse of coke layer strongly.

The objective of this paper is to analyze the particle behavior in bell-type charging process of actual blast furnace by using Discrete Element Method (DEM). The circumferential balance of charged mass in the quad-hopper and the effect of the nut coke particle position in the quad-hopper on the traveling behavior and the segregation were discussed. The mass flow rate discharged from the rotating chute was fluctuated with the time, and the peak values gave when the directions of the chute movement became same as the one of the conveyor. It leads to the unbalance of charged particles in each part of the quad-hopper. The nut coke moved to the upward in the sintered ore particle layer during traveling to large bell from the quad-hopper due to the particle segregation, when they were segregated at the bottom of hopper. However their relative positions moved downward when they were segregated at the top, because the time for starting discharging of nut coke became faster. The installation of the damper at the way to the small bell from the hopper affects on the circumferential balance of mass of nut coke. Most of nut coke particles were charged at near the wall of blast furnace, and the small peak of the distribution of its specific charged mass was seen around 3.0 m in the radial distance from the center, it caused by the particle segregation during flowing on the particle layer. The relative radial distribution of the nut coke particles wasn't affected by their positions in the large bell and the total mass. Thus, keeping the circumferential balance of nut coke mass in the large bell is very important. The position of nut coke particle didn't affect on the segregation of sintered ore. The radial distributions of relative charged mass for all conditions were quite similar.

No abstract

The objective of this paper is to improve the computing time for numerical analysis of particle charging process by using Discrete Element Method. The rule for ignoring the calculations of contact forces and updating trajectories of unmoved particles were discussed. When the relative displacement of a particle within certain calculation steps became less than 0.1% of particle radius, this particle was determined to be unmoved and the calculations of this particle were ignored. The computing time was improved significantly when this new method was used, and its calculation speed was more than two times faster than that of original. It was found that this speed-up method is more useful for the cases that the particle becomes unmoved in short time or the height of charged bed is large. The simulation of charging process in an industrial-scale surge hopper was studied by using new method, the calculation speed became 2.88 times faster than that of original, and the quite similar particle size segregation between original and new methods was given. This new method for speed-up of the charging process in DEM is very useful, and the charging processes of the industrial scale storages can be simulated by using this method.