Towards green steel-energy and CO2 assessment of low carbon steelmaking via hydrogen based shaft furnace direct reduction process

Under current stringent climate policies, the iron and steel industry, as a major contributor to industrial CO2 emissions, urgently needs the development of low-carbon metallurgical technologies. This work focuses on the hydrogen-based shaft furnace process, which can utilize green energy to significantly reduce CO2 emissions. This work combines the hydrogen-based shaft furnace CFD model, regression equations, and Aspen Plus model to develop a multi-gas source DR (Direct Reduction) plant model. This combination significantly reduces computation time while maintaining predictive accuracy. The transformation from COG (Coke Oven Gas)-DR to H2-DR plant was studied, showing that the top gas circulation process greatly reduces the net carbon input of the entire DR plant. However, the energy consumption of electrolytic hydrogen production limits the transformation of COG-DR plant to H2-DR plant. The process CO2 emissions depend largely on electrical energy footprint. Under traditional electrical energy footprint, the CO2 emissions of H2-DR-EAF (Electric Arc Furnace) route are about four times those of the COG-DR-EAF route. Only when using green source energy does the H2-DR-EAF route achieve the lowest CO2 emissions among all routes, at 344 kg/tls, which is 79 % lower than that of the BF (Blast Furnace)-BOF (Basic Oxygen Furnace) route.