Combustion characteristics of Zhundong coal by staged and direct chemical looping
Chemical looping combustion is recognized as an efficient technology for low-carbon emissions,offering distinct advantages in enhancing fuel utilization and decreasing CO2 emissions.In this study,Fe2O3/Al2O3 oxygen carrier was employed in a two-stage fixed-bed reactor to conduct direct and staged chemical looping combustion experiments of Zhundong coal.The physicochemical properties of the fresh and spent oxygen carrier has been investigated.Results indicate that the carbon conversion and CO2 selectivity of the chemical loo-ping combustion of Zhundong coal pyrolysis volatiles increase with increasing temperature and OC/C ratio.The enhanced OC/C ratio and temperature contribute to an improves carbon conversion during the chemical looping combustion of Zhundong coal char,but with a de-crease in CO2 selectivity.Compared to direct chemical looping combustion of coal,staged chemical looping combustion significantly im-proves the CO2 selectivity and slightly reduced the carbon conversion under the same condition.At a reaction temperature of 800 ℃,the CO2 selectivity of staged chemical looping combustion reaches to 89.51％,representing a 29.18％increase compared to direct chemical looping combustion.At a reaction temperature of 950 ℃,the carbon conversion of staged chemical looping combustion is 60.40％,which is 6.78％lower than that of direct chemical looping combustion.The reduction of degree the oxygen carrier with char is higher than with coal pyrolysis volatiles,suggesting that the reaction between char and the oxygen carrier is one of the limiting factors in the chemical looping combustion of coal.This study provides a crucial theoretical foundation and technical support for achieving low-carbon clean com-bustion of Zhundong coal.
chemical looping combustionoxygen carrierpyrolysis volatilescharselectivity of CO2
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