The Influence of Hydrogen Injection on the Reduction Process in the Lower Part of the Blast Furnace: A Thermodynamic Study

摘要

To reduce the CO_2 emission in ironmaking, H_2 is suggested to be the best alternative to the fossil fuels used in the blast furnace, and it attracts increasing attention in recent decades. It is well known the reduction behavior of iron oxides with hydrogen is significantly different from that with carbon. Thus, the operation of the blast furnace will change greatly if hydrogen is injected into the blast furnace. However, the influence of hydrogen injection on the reduction process in the blast furnace is seldom addressed in the literature. In this work, the principle of minimum Gibbs free energy is applied to analyze the thermodynamics under working conditions in the lower part of the blast furnace taking into account hydrogen injection. Results indicate that the addition of H_2 plays a crucial role in the thermal balance of the system and the reduction process of wustite. When the amount of heat supplied by hydrogen injection is less than 25%, the gas utilization ratio increases by injecting hydrogen. In this circumstance, wustite can be completely reduced by carbon, and no water is formed because H_2 only acts as a transmission medium. The situation becomes totally different when it is over 25%. and the coexistence of carbon and wustite can be observed.