Coal flow and combustion characteristics under oxygen enrichment way of oxygen-coal double lance

Under great economic and environmental pressure, to further increase the pulverized coal rate and decrease the coke rate has been an urgent task for the production of the blast furnace. Compared to other methods, oxygen-enrichment is a simpler, more effective and more economical method for increasing the pulverized coal rate. However, the effect of conventional oxygen-enrichment in hot blast on coal combustion is less. The local oxygen-enrichment way can increase the oxygen concentration around the coal particles significantly, very benefiting coal combustion. However, the room-temperature oxygen also has some adverse effect on coal combustion. Therefore, a proper local oxygen-enrichment method is necessary for further increase of the pulverized coal rate. The coal combustion under local oxygen-enrichment becomes more complex. To further increase the coal burnout and understand the oxygen-coal combustion characteristic, in this study, a three dimensional model is developed to simulate the coal/oxygen lance-blowpipe-tuyere-raceway of a blast furnace. The effect of local oxygen-enrichment method of oxygen-coal double lance on coal combustion is investigated in detail. The simulation results show that the local oxygen-enrichment way of oxygen-coal double lance is very beneficial to coal combustion. The maximum increase of the coal burnout is about 12.84%. (C) 2017 Elsevier Ltd. All rights reserved.