First techno-economic assessment of a monoethanolamine-based CO2 capture plant applied downstream the Electric Arc Furnace for steel production

Abstract

Extreme climate events, such as heatwaves and floods, are becoming increasingly recurrent and owe their existence to global warming, which has been triggered by uncontrolled atmospheric emissions of GreenHouse Gases (GHG) from various human activities. Apart from the energy sector, the industrial sector, to which the iron and steel industry belongs, ranks third in the top-five greatest anthropogenic CO₂ emitting sectors. One of the mostly employed technology for CO₂ removal from different gaseous streams is based on chemical absorption, with an aqueous solution of monoethanolamine (MEA) considered as the benchmark solvent. This paper is the first work in the literature assessing the technical performance of a MEA-based post-combustion CO₂ capture system implemented downstream the electric arc furnace (EAF), which operates in non-steady-state conditions, at a mini-mill steel production plant and for which industrial application has recently become of interest for a cleaner steel production. A rate-based Aspen Plus® V11 model has been developed, for studying the best operating conditions for such plant via a parametric study. The effect of the lean solvent loading, α_LEAN, the absorber packing height, H_abs, the regenerator operating pressure, P_stp, and the regenerator packing height, H_stp, on user-defined key performance indicators (KPI) has been examined. These KPIs quantify the process performance in terms of the process requirements, thus enabling to select the best operating parameters. From all the KPIs, the thermal energy requirements (TER) at the reboiler was the one sought to be reduced the greatest. The CO₂ capture plant was initially designed under the assumption of a steady flue gas flowrate entering the absorber. This assumption was later revised, leading to a proposed modification of the conventional process scheme to enable flexible operation, making this technological solution feasible and suitable for full-scale industrial application. This modification allows the plant to accommodate variations in flue gas flowrate and composition due to the intermittent operation of the EAF plant. An economic analysis indicated that the cost of CO₂ removal is approximately 116$/tCO₂. This cost is competitive with the current cost of the EU Emissions Trading System (ETS) allowances. In the end, two possible scenarios for managing the captured CO₂ – utilization or storage – have been considered.