Advanced Packed-Bed Ca-Cu Looping Process for the CO2Capture From Steel Mill Off-Gases

A novel configuration of the Ca-Cu looping process based on dynamically operated packed-bed reactors is proposed to convert blast furnace gas (BFG) into H-2/N(2)and highly concentrated CO2, accompanied by a large amount of high-temperature heat. Preliminary energy and mass balances of the process reveal that around 30% of the BFG can be upgraded via calcium assisted water gas shift (WGS) if only BFG is used as reducing gas in the reduction/calcination stage. A higher amount of H-2/N(2)can be produced by using other steel mill off gases, such as coke oven gas (COG) or basic oxygen furnace gas (BOFG), or natural gas in the regeneration of the CO(2)sorbent. This decarbonized fuel gas could be used for onsite power generation or to obtain sponge iron by a Direct Reduced Iron (DRI) process, increasing the overall capacity of the steel plant. Energy efficiencies higher than 75% have been calculated, reaching maximum values around 88% in case of using natural as fuel gas for the sorbent regeneration stage. Low values for the specific energy consumption of around 1.5 MJ(LHV)/kg(CO2)and CO(2)capture efficiencies higher than 95% support the further development of the proposed Ca-Cu looping process.