Modeling and simulation of the use of direct reduced iron in a blast furnace to reduce carbon dioxide emissions

Abstract

The reduction of greenhouse gas emissions in all economic sectors is an important goal of the transition towards a sustainable energy system. The steel industry is one of the largest industrial CO2 emitters and roughly two-thirds of the annual steel production can be attributed to the conventional blast furnace/converter route. In this study, the potential to reduce CO2 emissions from blast furnace processes by using direct reduced iron (DRI) as a pre-reduced input material is examined. An existing blast furnace model constructed using Aspen Plus in combination with FactSage/ChemApp is applied. Different types of DRI produced by gas-based processes (i.e., the Midrex and Energiron process) are considered. These are assumed to be produced partially using pure hydrogen as a reducing gas, which is generated renewably by water electrolysis. The simulation results show that the CO2 emissions can decrease significantly with the measure implemented. At the most favorable operation conditions using 400 kg/tHM of DRI (tHM = ton of produced hot metal), the CO2 emissions of the blast furnace can be reduced by up to 26.7% relative to typical operations using pulverized coal at an injection rate of 120 kg/tHM.