Application of the DMXTM CO2 Capture Process in Steel Industry

Abstract

The VALORCO project coordinated by ArcelorMittal and funded by ADEME aims at reducing and valorizing CO2 emissions from steel industry. This paper presents the main results of task 1.1A of the VALORCO project dedicated to CO2 capture on blast furnace gases by means of amine scrubbing technologies. Blast furnace gases are characterized by high CO2 and CO partial pressures and the absence of oxygen. Since few literature data are available on the effect of CO on solvent degradation and CO2 absorption, experimental work was needed. In this context, three IFP Energies nouvelles (IFPEN) processes initially developed for CO2 capture on coal power stations were evaluated for blast furnace applications: HicaptTM process (MEA 30wt.%), Hicapt+TM process (MEA 40wt.%) and DMXTM process (Demixing solvent).For the three processes, it was shown that CO absorption is slow and mainly physical even though kinetic studies highlighted a chemical absorption of CO in CO2-free amine solutions, especially for MEA solvents. This chemical absorption is however largely inhibited in presence of CO2 which limits this phenomenon to occur in real process conditions. Degradation studies in batch reactors showed a low impact of CO on MEA solutions and no quantitative effect on DMX solvent. Compared to flue gases containing oxygen, amine degradation observed with blast furnace gases is globally negligible for all tested solvents. Above conclusions were confirmed with two long-run tests (∼1500h) on a CO2 capture mini-pilot at IFPEN. These tests also underlined a high CO2/CO selectivity with very few CO in CO2 produced, the possibility of reaching high CO2 capture rate (>99.5%) and the good operability for all studied processes. Moreover, DMX solvent allows using carbon steel as process metallurgy and producing CO2 at 6 bara which turn into subsequent economical savings. Considering an available steam at 21 €/t, it would be possible to produce CO2 from blast furnace gases at around 40 €/t by using the DMXTM process.