Mathematical Simulation on Blast Furnace Operation of Coke Oven Gas Injection in Combination with Top Gas Recycling

摘要

In order to further improve blast furnace operational performance, reduce carbon emission, and increase gas utilization efficiency under only coke oven gas (COG) injection, a blast furnace process of COG injection together with top gas recycling through tuyere injection (TI) and/or shaft injection (SI) had been mathematically simulated in this study. The effects of this new process on in-furnace status, operation parameters, and energy utilization are investigated by means of multi-fluid blast furnace model. The results show that compared with only COG injection, solid temperature slightly decreases and cohesive zone tends to move downward and narrow under simultaneous COG injection and top gas recycling. Meanwhile, the reduction degree of iron-bearing burdens evidently increases before entering cohesive zone due to more involvement of hydrogen into indirect reduction. Furthermore, the operation of COG injection combined with top gas recycling can achieve blast furnace ironmaking with low carbon emission, low energy consumption, and high efficiency. For example, hot metal productivity and corrected CO utilization efficiency under COG injection and TI increase by 13.87 and 6.95%, respectively. Additionally, carbon emission ratio and energy consumption decrease by 39.57 and 15.78%, respectively. Taking into account in-furnace status, operational parameters, and energy consumption, the operation of COG injection and top gas recycling through TI is recommended as more feasible choice for the possible practical application.