Development and evaluation of various off-gas utilization processes for sustainable steelmaking industry

Abstract

FINEX is one of alternative steelmaking processes characterized by direct use of coal. The process releases significant quantities of FINEX off-gas (FOG), which is currently used for electricity generation through combined cycle power plant. In order to reduce net carbon dioxide emissions of FINEX process, this study proposes three FOG utilization processes: post-combustion capture, pre-combustion capture, and methanol production. These processes are simulated using Aspen Plus and evaluated in terms of net CO$_2$ emissions using CO$_2$ lifecycle assessment. Techno-economic analysis is conducted to estimate additional cost caused by the application of the proposed processes, and the cost of CO$_2$ avoidance is estimated to compare economic feasibility of the processes. The post-combustion capture from FOG was observed to reduce the largest amount of CO$_2$ emission, which is 35% less than the status quo for the FOG utilization process. Pre-combustion capture from FOG showed the lowest CO$_2$ avoidance cost, 67 USD/ton. Although the methanol process presented lower CO$_2$ reduction effect compared to the post-combustion capture and higher CO$_2$ avoidance cost than the pre-combustion capture, it was revealed through sensitivity analysis that global warming impact (GWI) of the mixed electricity and methanol price greatly affect CO$_2$ reduction effect and CO$_2$ avoidance cost, respectively.