Chemical Looping Combustion Performance Of Coal With Natural Iron Ore As Oxygen Carrier

Chemical looping combustion(CLC)technology could realize grade use of energy of fuels by dividing the combustion into two step,i.e.oxidation of fuels with lattice or molecular oxygen from an intermediate(oxygen carriers,OC)and regeneration of the used OC.Through this process,CO₂was inherently separated thus saving the energy of CO₂capture and storage.Environmentally-friendly,cheap,stable,efficient and reactive OC was key to the development of CLC technology.In this work,two natural iron ores,Hematite and Ilmenite were used as OC,and CLC experiments were conducted with two coals at a laboratory-scale fixed bed reactor.The effect of addition,temperature and cycling test on the performance of the modified ores were examined.The main results and conclusions are summarized as follows.(1)Higher temperature is favorable for improving the gasification rate of the two coals,and also enhances the reactivity of the two iron ores.Comparatively,Ilmenite show better reactivity as the carbon conversion and rate in CLC with Ilmenite are higher than those with Hematite.The addition of K₂CO₃into the two ores could effectively increased the carbon conversion and CO₂selectivity osf CLC with Shengli Lignite.The optimum addition of K₂CO₃was 10 wt%.The ores modified with 10%K₂CO₃presented little agglomeration and sintering in 10 cycles of CLC process,but K₂CO₃was gradually lost which resulted in the decrease of reactivity of the modified oxygen carrier.(2)The addition of CuO also obviously enhanced reactivity of the natural ores,and both the carbon conversion and rate were increased in CLC with Shengli lignite.The optimum addtion of CuO was 10 wt%.The carbon conversion of Shengli lignite in CLC with the 10Cu-hemand 10Cu-ilm both reached above 90%,and the two oxygen carriers remained stable in 10 cycles.No obvious agglomeration or sintering were observed from SEM and XRD analyses,indicating their stable structure and reactivity.Thus the natural ores modified with 10%CuO are more suitable to be used as oxygen carriers for CLC using coal as fuel.