Modelling in-furnace phenomena of pulverized coal injection in ironmaking blast furnace: Effect of coke bed porosities

In order to understand the complicated in-furnace phenomena of pulverized coal injection in ironmaking blast furnaces, a three-dimensional CFD model has been developed to simulate the gas–particle behaviors in not only raceway cavity but also the surrounding coke packed bed under practical conditions. The model considers two different fuels, pulverized coal and coke bed. The model is validated against the measurements in terms of coal burnout and gas composition, respectively. The typical in-furnace phenomena are simulated. Then an array of parametric study is carried out to evaluate the effects of local porosities of different coke bed zones. The qualitative and quantitative analysis is conducted. The results indicate that the local porosities of different coke bed zones can affect the coal burnout and gas composition differently: significantly in the deadman zone but insensitive in the dripping zone. In addition, the present model is able to provide a more reliable indicator to describe coal burnout, i.e. burnout over raceway surface, rather than burnout only along the centerline. The model is expected to be useful for understanding the flow-thermo-chemical behaviors and then optimizing the PCI operation in full-scale blast furnaces.

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► Effects of coke bed porosities on coal combustion are studied using an in-furnace model.
► Large recirculation region of raceway behaves significantly different from tuyere centerline.
► Local porosity of deadman zone of the coke bed affects coal combustion significantly.
► Local porosity of dripping zone of the coke bed affects coal combustion insignificantly.
► Burnout over raceway surface reflects effect of coke bed porosities rather than along tuyere axis.