Combustion characteristics of coal particles in blast furnace raceway under various injection patterns and operations

Pulverized coal combustion across the regions of blowpipe, tuyere, and raceway of blast furnace under various operating conditions are studied numerically. Three different lance configurations, including a single lance, a double air-cooled coaxial lance, and an oxy-coal lance with different oxygen enrichment patterns, are taken into consideration. The coal combustion efficiency by the double lance injection is 5.1% higher than that by single lance injection. From the calculated temperature by the oxy-coal lance, coal ignition is retarded due to the cooling effect of enriched oxygen flowing through the lance annulus, resulting in the moderation of pressure loss within the raceway. The enriched oxygen becomes the combustion enhancer in the downstream of coal plume after ignition is triggered. Consequently, the coal burnout under the oxy-coal lance injection is comparative to that under the double air-cooled lance injection. The performance of blast furnace may be improved with the advantages provided by the oxy-coal lance injection. Compared with the single lance injection, coal trajectories under the oxy-coal lance injection are closer to the tuyere exit due to the higher inertia force of coal particles against hot blast.