Modelling in-furnace phenomena of coal/coke combustion in a blast furnace: Effects of coal properties

Pulverized coal injection is widely practiced in ironmaking blast furnaces. High burnout is desired for high coal rate operation. A three-dimensional integrated mathematical model of the combustion of pulverized coal and coke is developed. The model is applied to the blowpipe-tuyere-raceway-coke bed region in a commercial blast furnace. Themodel is validated against the measurements in terms of coal burnout and gas composition, respectively. The results show that, the in-furnace phenomena of PCI operation can be studied numerically. The effects of coal properties are examined in terms of coal burnout and gas composition, respectively. The burnout is examined in two ways: along the tuyere axis and over the raceway surface. A coal of fine particle size or high volatile content could give an increased burnout and would affect the gas composition considerably. In addition, compared with the burnout calculated along the tuyere axis, the burnout averaged over the raceway surface is a more sensible parameter to represent the unburnt char entering the surrounding coke bed. The model offers a powerful simulator for describing the in-furnace phenomena of PCI operation in blast furnace.