Numerical Investigation of Gas and Slag Flow in the Packed Bed

In the lower part of the blast furnace (BF), with gas introduced through tuyeres and slag flowing downward from cohesive zone to the hearth, strong cross-flow of gas relative to the slag occurs in front of the raceway, while in the upper parts, counter-current flow of gas and slag exists. The interaction between gas and slag is closely associated with the special flow phenomena such as loading, flooding, or channeling. These phenomena link to furnace irregularities, affecting smooth operation and limiting production. Therefore, understanding the gas–slag interaction and its influencing factors is critical for process control and stable BF operation. In the current study, counter-current gas–slag flow in the packed bed is numerically investigated using the Volume of Fluid technique. Different superficial gas velocities, slag properties, packing structures, and gas inlets are considered in the study. The gas–slag flow behavior at a mesoscopic level was visualized. In particular, localized slag flooding and gas channeling caused by the strong interaction between gas and slag were uniquely identified. Gas channeling, which is a critical phenomenon in a packed bed with counter-current gas–slag flow, can be enhanced by more wetting and higher viscosity slag, and poor permeability regions. It can be speculated that significant gas channeling in the BF can inevitably occur prior to operational limits being reached. In the BF process, the formation of permanent gas channeling and large slag rivulets should be avoided to maintain the proper contact between phases and furnace permeability.