Effects of hydrogen-rich fuels injection on blast furnace ironmaking process

To reduce carbon emission in the ironmaking process of blast furnace, thermodynamic behaviors of hydrogen-rich or pure hydrogen fuels, i.e. natural gas, coke oven gas, ammonia gas and hydrogen gas, during injection into blast furnace tuyeres were analyzed. The effects of hydrogen-rich gas replacement ratio, preheating temperature, injection volume, and oxygen enrichment ratio on the main indicators of blast furnace were investigated based on material and thermal balances. Results show that increasing oxygen enrichment ratio of blast can reduce belly gas volume, and significantly increase theoretical combustion temperature. Though preheating of hydrogen-rich gas can significantly increase theoretical combustion temperature, but has no obvious effect on belly gas volume. Increasing the replacement ratio can decrease the increment of belly gas volume even to a level lower than the reference value, but exerts no significant influence on theoretical combustion temperature. To maintain constant thermal energy of belly gas, the required oxygen enrichment ratio for injecting hydrogen-rich gas per volume ranging from high to low is natural gas, coke oven gas, hydrogen gas, and ammonia gas. Whether it increases or decreases with the increasing of gas injection depends on the replacement ratio. High replacement ratio and oxygen enrichment ratio are conducive to the increase of natural gas injection volume, whereas ammonia gas needs to lower the oxygen enrichment ratio to maintain the constant high-temperature gas thermal energy under different replacement ratios. This study can provide theoretical support for determining suitable hydrogen-rich fuels of blast furnace.