Investigation of Coke Collapse in the Blast Furnace Using Mathematical Modeling and Small Scale Experiments

Abstract

Burden distribution plays a key role in controlling the gas flow conditions inside a blast furnace. The distribution of ore and coke influences the gas permeability distribution in the lumpy zone and also in the cohesive zone, where the gas flows mainly through the coke slits. Charging an ore dump on coke can sometimes cause the coke layer to collapse under the force of the heavier ore particles. This is known as 'coke collapse' or 'coke push', which results in a higher coke fraction near the center of the furnace than expected. In this work coke collapse phenomena are evaluated on model charging programs using small scale experiments and Discrete Element Modeling (DEM). DEM simulations were used to study the extent of collapse for different charging programs, and experiments were undertaken to verify the results of the simulations. The slope stability method was used to classify the collapse conditions into no collapse, impact failure or gravity failure, depending on the stability of the coke layer. The findings were also compared with results from an in-house mathematical model, which was modified to consider the effect of the collapse on the underlying layer. The corrected mathematical model was found to show results in general agreement with results from the DEM simulation.

Review on Modeling and Simulation of Blast Furnace

“…It also provides the basic boundary information to study the burden descent and associated phenomena in the BF body. For a long time, such prediction has mainly relied on the models derived from the motion of a single particle or particle assembly . In recent years, the DEM approach, which considers all individual particles and their interaction with each other, has become a promising tool to guide burden charging operation …”

“…For a long time, such prediction has mainly relied on the models derived from the motion of a single particle or particle assembly. [121][122][123][124] In recent years, the DEM approach, which considers all individual particles and their interaction with each other, has become a promising tool to guide burden charging operation. [79,125] Figure 11 shows a representative application of DEM in simulating the bell-less charging system mainly used in modern BFs.…”

“…Both phenomena significantly affect the burden radial distribution and can readily be predicted using DEM charging models over a wide range of conditions. [79,[124][125][126][127][128][129][130][131][132] Such capability is, however, difficult to achieve by single particle based models. [121][122][123][124] For example, the formulation of coke layers, although complicated, can be well predicted by the DEM simulations simply based on spherical particles if the friction coefficients are carefully chosen, as demonstrated in the work of Liu et al [125] (see Fig.…”

Numerical Investigation of Coke Collapse and Size Segregation in the Bell-less Top Blast Furnace

“…This confirms that DEM is a feasible and reasonable way to investigate the coke collapse. 10) Therefore, in the present work, a three dimensional model of blast furnace top is established based on DEM. Then this model is used to investigate the effects of rotating chute angle, rotating speed and the amount of sinters on the coke collapse and corresponding size segregation.…”

Modelling of Coke Layer Collapse during Ore Charging in Ironmaking Blast Furnace by DEM

“…Furthermore, in the actual blast furnace, the coke layer thickness after collapse cannot be measured because the coke layer is covered with ore layer. Since many experimental studies have been carried out to investigate the coke collapse and clarify dominant factors [1][2][3][4][5][6]. Some studies have used numerical method like Discrete Element Method (DEM) [7] for better understanding of the phenomena involved.…”