CFD-DEM modelling of raceway dynamics and coke combustion in an ironmaking blast furnace

In this study, a CFD-DEM reacting model featuring thermochemical sub-models is developed for describing gas-solid reacting flow related to raceway dynamics and coke combustion in an ironmaking blast furnace (BF). The simulation results show that a ring-type zone is formed around the cavity where the coke combustion and gasification occur with a large amount of heat released, leading to intense momentum and thermochemical exchanges in this zone. Heat fluxes contributed from radiation and reaction dominate total heat transfer during the coke combustion, while conductive heat transfer is insignificant. Then, the impacts of key operating parameters on raceway evolution are quantified. The simulation results indicate increasing the blast gas velocity from 210 m/s to 230 m/s and oxygen mass fraction from 0.17 to 0.27, the cavity depth is increased by 42.3% and 20.8%, respectively; lower inlet velocity, higher bed temperature, higher oxygen mass fraction leads to more CO production and the resulting better BF performance.