CFD Model of Coal Blends Combustion and Effects of Some Parameters

The combustion of coal blends is widely practised in blast furnace. It is desirable to characterise the combustion behaviours of coal blend and its components. A comprehensive three-dimensional numerical model is developed to simulate the flow and combustion of binary coal blends. In the model, two component coals are tracked separately and more mechanisms are considered for char reactions rates. The model is applied to a pilot-scale combustion test rig, which features an inclined co-axial lance. The model is validated against the measurements under a range of conditions. Then the effects of some operational parameters on burnout are investigated. The simulation results indicate that, 1) a synergistic effect on final burnout is observed and explained by the interactions between two coals in terms of particle temperature and volatile content; 2) the synergistic effect is more pronounced for a blend with a large fraction of high volatile coal, which can be used to compensate for the decreased burnout under high coal rate operation. The model provides an effective tool for the design of coal blends in the practice of blast furnace.