Investigating effect of coke porosity on blast furnace performance based on multi-physical fields

Reducing coke use is an effective measure to reduce carbon emission and energy consumption in the blast furnace (BF) ironmaking. Essentially, BF is a high-temperature moving bed reactor, where complex physical transformations coupled with complicated reactions occur. This makes it challenging to investigate the factors determining BF performance with the conventional method. A multi-physical field coupling mathematical model of BF was thus developed to describe its mass and heat transfer as well as its intrinsic reactions. Then, the proposed model was validated with the production data. Under coupling conditions, influences of dominating reactions on BF performance (temperature distribution, gas distribution, iron formation reaction, and direct reduction degree) were revealed. The results indicated that coke combustion, indirect reduction, and direct reduction of iron ore mainly took place nearby the shaft tuyere, cohesive zone, and dripping zone, respectively. Besides, the rate of coke solution loss reaction was increased with the rising coke porosity in the cohesive zone. Considering the effect of coke porosity on the efficiency and stability of BF, the coke porosity of 0.42 was regarded as a reasonable value.