Three-dimensional DEM Study of Coal Distribution in the Melter Gasifier of COREX

Abstract

COREX is one of the commercialized smelting reduction ironmaking processes. It mainly includes two reactors: a reduction shaft and a melter gasifier (MG). Lump coal is used in the MG to generate reducing agents, and hence its distribution plays an important role in determining the temperature distribution and the reduction of iron ores. To understand the formation of burden profiles, a three-dimensional discrete element method (DEM) model is established and validated against experimental tests. The effects of key operational parameters such as the chute angle and the rotational speed are investigated, and the underlying mechanisms in the formation of an asymmetrical pile are analyzed. The results show that the asymmetrical pile is intrinsic to the discharge system due to the outward motion of lump coal. The results also reveal a significant size segregation of lump coal along the radial direction. Small particles tend to accumulate in the inner side of the pile while the large ones have large fractions in the outer side. The effect of the rotational speed is minor within the range from 3 to 12 rpm. These findings are helpful for the control and optimization of the MG to improve its energy efficiency.

Discrete Particle Simulation of Solid Flow in a Large-Scale Reduction Shaft Furnace with Center Gas Supply Device

“…blast furnace [10][11][12][13][14][15] and smelting reduction process such as COREX and FINEX. [16][17][18][19][20] The detailed micro-dynamic information of individual particles such as particle velocity and interaction forces between particles can be obtained by DEM. They are beneficial for understanding the flow of burden materials in various ironmaking process.…”

Experimental Study of the Effects of Operation Conditions on Burden Distribution in the COREX Melter Gasifier

“…[22][23][24][25][26][27][28][29] Several numerical studies on the COREX MG were conducted. Li et al 22) developed a model based on the discrete element method (DEM) to analyse the particle trajectory, falling location and burden surface profile.…”

“…The effect of burden voidage on gas flow was discussed. You et al 24) developed a DEM model to investigate the effect of chute angle and rotational speed on burden profile in a COREX MG. The asymmetrical pile and particle size segregation were also discussed.…”

“…Particle segregation due to size difference also affect the reduction process in an MG. To quantify particle segregation, a segregation index (SI) is introduced, 24) given by (1) where M k is the mass fraction of burden materials with size k in the sample, and M 0,k is the initial mass fraction of the burden materials in the batch. For a region with SI k > 0, it means that the particles with size k tend to accumulate in that region, and vice versa.…”

Solid Flow in a Shaft Furnace in Smelting Reduction Process under Circumferential Imbalance Conditions

“…In these flows, the motion of particles, as a densely packed bed, may have a significant impact on the flow of other phases and thus on the operation efficiency of the entire production. Hence, the transient features of solids are crucial in the smelting process …”