2018 Volume 51 Issue 10 Pages 855-864
Chemical-looping coal combustion (CLC) is a high efficiency technology for the conversion of coal and the potential capture of CO2 capture. The CLC is based on the transfer of oxygen from air to the fuel by a solid oxygen carrier. This study, investigated ilmenite reduction contained two steps of Fe2O3 to FeO, and FeO to Fe by CO and the conditions that avoid the deep reduction with multiple cycles by using TG. Reaction models for the reduction of ilmenite with multiple cycles were examined. A synthetic Fe2O3/Al2O3 oxygen carrier was also tested for comparison. Ilmenite re-oxidation by air after a second reduction step caused particle agglomeration, since Fe oxidation produces large amount of heat. To protect against the deep reduction of FeO to Fe in ilmenite, short reduction times and the incomplete reduction of Fe2O3 to FeO can be used. The reduction of iron oxide in the reduction of Fe2O3 to FeO step can also be limited when 0.3< CO/(CO+CO2) <0.7. Reaction models for the reduction of ilmenite with multiple cycles were examined.