Application of fractal theory on raceway boundary in COREX melter–gasifier model

Abstract

The raceway has been studied extensively both theoretically and experimentally. In this study, particle velocity contours have been developed to define the raceway boundary. The raceway boundary is coarse and fragmentised, but all of the previous studies are based on Euclidean geometry, which regard the dimension of the raceway as an integer. In this paper, the fractal method of calculating raceway size, which describes the boundary with extremely irregular or fragmented characteristics, is on the data from a cold physical model of the raceway. The results show that the precise raceway boundary can be obtained by the particle velocity contours, that the surface area of the ellipsoidal raceway based on fractal theory is larger than that based on Euclidean geometry and that the data can be used as original boundary conditions of the flow and chemical reaction in the raceway region.

DEM Simulation of Burden Distribution in the Upper Part of COREX Shaft Furnace

“…[5][6][7] According to the practical operation, it has been found that the quantity and quality indexes of COREX process are directly determined by the shaft furnace operation. [8][9][10][11] Although the role of shaft furnace plays is similar with that of lump zone in blast furnace, there are some differences existed between them in terms of gas composition and distribution, as well as burden distribution, which is of significant importance for shaft furnace. 1,12) Many researchers including the authors pay much attention to burden distribution in blast furnace numerically and experimentally, [13][14][15][16][17] while few researchers studied burden distribution in COREX shaft furnace for its short history and few instruments.…”

Numerical simulation of raceway phenomena in a COREX melter–gasifier

“…The physical experimental results reported in an earlier paper by the present authors show that the particles in raceway can make rotation under the condition without chemical reactions and particles consumption [25] . In order to analyze the particles velocity further, the velocity vectors of particles around the tuyere are displayed alone, as shows in Fig.…”

“…Based on a real COREX melter-gasifier and its physical model used by the author's research group [25] , are not considered. The gas phase was considered to be incompressible and iso-thermal.…”

“…In a previous paper of author's research group [25] , based on physical simulation of the COREX melter-gasifier and analysis of tracer particles, the velocity contours of particles in raceway were obtained. The result indicates that the particles velocity is the greatest in the central area of the raceway, and the particles velocity is decreased gradually with increasing distance from the raceway center.…”

The Effect of Operational Parameters on the Characteristics of Gas–Solid Flow Inside the COREX Shaft Furnace

“…7,8,[16][17][18][19][20][21][22] There are few numerical simulations relating to the shaft furnace, which also plays an important role in the practical operation of the whole COREX process. [23][24][25][26] Li et al 27 studied the characteristics of binary size burdens' movement in the COREX shaft furnace based on the discrete element method (DEM). They then verified and calibrated a DEM simulation with experiments using yellow rice and soybean with respect to burden distribution and profile.…”