Effect of Ternary Eutectic Salt on the Calcium Sulfate Oxygen Carrier for Chemical Looping Combustion of Coal Char

摘要

The effect of a ternary eutectic salt (43.5 Li2CO3-31.5 Na2CO3-25 K2CO3) on the CaSO4 oxygen carrier for chemical looping combustion (CLC) of coal char is experimentally investigated in a bench-scale fluidized-bed reactor with steam as the gasification agent at atmospheric pressure and 925 degrees C. The ternary eutectic catalyst is added to the CaSO4 oxygen carrier by physical mixing and impregnation, respectively. The enhanced carbon conversion and shortened reaction time in the fluidized bed reactor, coupled with the high weight loss rate of CaSO4 reduction with CO in the thermogravimetric analyzer (TGA), suggest that the reactions of coal char gasification and CaSO4 reduction are synergistically catalyzed in the presence of the ternary eutectic salt. The modified oxygen carriers prepared by physical mixing and impregnation show no significant difference in carbon conversion and gasification rates according to the experimental results. The sample with catalyst impregnated into the mixture of anhydrite and coal char gives higher activity compared to the samples with catalyst impregnated into the coal char or anhydrite solely, due to the more uniform distribution of the catalyst.