The use of coke with high reactivity in the ironmaking blast furnace (BF) has yet to be explored, and a thorough understanding is still required to clarify the effect of coke reactivity on the BF gas utilization efficiency. In this paper, a one-dimensional kinetic model of the BF is presented and the accuracy of the model is verified. The model is then applied to analyze the effect of coke reactivity on the gas utilization efficiency of the BF. The results show that, under the operating conditions considered, the height of indirect reduction region and the starting temperature of coke solution loss reaction decrease with the increase of coke reactivity. Moreover, coke reactivity is first, directly proportional to gas utilization efficiency, and then, inversely proportional to it. In addition, high-reactivity coke may not improve gas utilization efficiency in case of high H2 content. Both, lowly and highly reactive coke need to be combined with highly reducible iron ore to maximize the gas utilization efficiency. Nevertheless, only appropriately reactive coke can combine with lowly reducible iron ore to obtain an optimal gas utilization efficiency. Hence, it is necessary to select coke with appropriate reactivity, in accordance with iron-ore reducibility, instead of blindly pursuing high-reactivity coke in actual operation.
Oxygen enrichment is believed to improve productivity and reduce fuel consumption, while gas fuel injection is assumed to improve the product yield and quality in iron ore sintering process. It is important to understand the mutual effect of oxygen enrichment and gas fuel injection for combined usage of these two techniques. A mathematical model is developed to simulate the sintering process with coke oven gas (COG) injection and oxygen enrichment, particularly focusing on predicting the quality and yield of sinter production, as well as NO
x
emission. The model is validated by comparing the model predictions with sintering pot test data, and numerical simulations are carried out to investigate the mutual effect of oxygen enrichment and COG injection. The results show that, compared with the conventional sintering process, with 0.5% COG injection and 30% oxygen enrichment, the mean melt quantity index (MQI) is increased by 4.1% and the mean cooling rate (CR) is decreased by 62.5%, showing that the sinter quality is improved significantly. The sinter yield is increased by 44.5%, whereas the NO
x
emission is increased by 8.3%. With the increase of oxygen enrichment from 21% to 30%, the sinter yield increases prominently first and then decreases a little, attaining its maximum at 30% of oxygen concentration. In addition, increasing oxygen concentration will increase the conversion rate of coke-N to NO
x
. Therefore, excessive oxygen enrichment is not only bad for sinter strength and yield, but also increases NO
x
emission.
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