Quantitative comparison of binary particle mass and size segregation between serial and parallel type hoppers of blast furnace bell-less top charging system

Uniform particle packed-bed permeability facilitates a smoother operation and a higher energy efficiency of the blast furnace ironmaking process. Two types of bell-less top charging systems, namely, serial and parallel type hoppers, are widely applied in practical production to distribute the burden particles into the furnace throat. The emergence of particle segregation behaviors directly influences permeability in radial and circumferential directions. In this work, after mapping 40 blocks with equal areas in the furnace throat, quantitative methods are proposed to characterize and compare mass and size segregation behaviors when binary-sized particles are charged from serial and parallel type hoppers. Based on the results obtained from discrete element method simulation, the average particle velocity in the horizontal x-y plane at the exit of the rotating chute under the serial type hopper is approximately 0.3 m/s greater than that under the parallel type hopper, which causes the difference in mass segregation in the radial direction. Furthermore, the velocity in the z-axial direction demonstrates a cosine-like curve under the parallel type hopper during the entire discharge process, which results in its mass segregation in the circumferential direction. The particle flow on the rotating chute concentrates with a narrower width under the serial type hopper, so, the small particles aggregate in the smaller central area. By contrast, the wider particle flow width under the parallel type hopper helps distribute the small particles into the larger central area. Moreover, the effect of particle size and chute inclining angle on the difference in the above segregation behaviors between the serial and parallel type hoppers are further investigated. (C) 2018 Elsevier B.V. All rights reserved.