Effect of Coke Size on Reducing Agent Ratio (RAR) in Blast Furnace

Abstract

The coke size’s effect on RAR (Reducing Agent Ratio, Fuel Ratio) should be estimated for the efficient blast furnace operation. The reaction and the heat exchange efficiency decrease by 0.2% and 3% per 1 mm increase of the coke size. This makes RAR increase by about 1 kg/t-p according to the 2-D numerical analysis under the stable blast condition. The coke sampling through the tuyere shows that the coke size is not linearly proportional to the charged coke size. The 2-D numerical analysis model shows that the gas utilization ratio is decreased by 2.5% for the case of deteriorated deadman state according to the increase of charging coke size by 5 mm. Moreover, the number of tapping is increased due to the increased coke size which makes the molten material drainage deteriorate at the coke bed of the tuyere level. From these results, the relationship between the coke size and RAR can be quantified and the optimal coke size can be determined according to the productivity for the stable blast furnace operation.