Computational Study of a Direct Reduction Furnace with Hydrogen-Rich Feed Gas

The steelmaking industry must urgently decrease its carbon footprint and the replacement of blast furnaces by direct reduction (DR) shaft furnaces operated on hydrogen-rich feed gas is being explored as a potential solution. Full hydrogen operation could practically null the carbon footprint of the ironmaking step but only if the electricity is completely green, but in regions with higher grid emission factors the carbon footprint may not be reduced substantially because of large indirect emissions. Recent studies have further indicated that it may be beneficial to include some carbon monoxide in the feed gas due to its positive impact on the heat supply and less endothermic reduction reactions. The present work explores computationally some options of operating a direct reduction furnace on feed gas of a high hydrogen content produced by fresh supply gas and regenerated top gas. The study analyzes the demand of fresh feed gas, the energy requirement and the CO₂ emissions of the different concepts, providing guidelines for possible future operation states of ironmaking DR furnaces.