CO2 Emission Reduction Potential in the Steel Industry by Integration of a Direct Reduction Process into Existing Steel Mills

In the context of climate change, the redn. of greenhouse gas emissions in all economic sectors is considered to be an important factor in order to meet the demands of a sustainable energy system. The steel industry as one of the large industrial CO2 emitters is currently highly dependent on fossil resources. In order to reduce coke consumption and thereby CO2 emissions while still being able to further utilize existing blast furnaces, the possibility of including a direct redn. process (DRP) into a fully integrated steel mill was investigated. Therefore, a blast furnace model, derived from literature data and implemented in Aspen Plus, was used to analyze the impact of DRI in the blast furnace process. Furthermore, a state-of-the-art DRP was modeled to investigate the possibility of substituting the reducing agent natural gas with hydrogen. A sensitivity anal. was carried out in order to find the boundary percentage of hydrogen as a reducing agent without penalty to the DRI quality. Lastly, the two modeled process steps were combined to form a route of producing hot metal. By varying boundary conditions of the DRP while recording the CO2 emissions of the two process steps, the overall potential for the redn. of CO2 emissions was estd. Within the simulated range a max. redn. of CO2 emissions of 25.8% relative to typical emissions of a blast furnace could be detd.