Investigation on coal ash fusibility and fluidity during the co-gasification of coal and coal indirect liquefaction residue

Abstract

Co-gasification of coal and coal indirect liquefaction residue (LR) could mitigate the environmental pollution caused by solid waste accumulation to a great extent. Therefore, in this work, anthracite coal and LR were co-gasified to solve the above-mentioned derived problems. The effects of LR addition on ash fusibility and fluidity were investigated by ash fusion temperature analyzer (AFTA), XRD, SEM-EDS and FactSage software. The results showed that with the increase of LR proportion, the ash fusion temperatures (AFTs) could be effectively reduced. The formation of mullite with skeleton structure was the main reason for the higher AFTs in Sihe coal ash (AS0). The addition of LR increased the Fe content in the mixed sample, thereby inhibiting the formation of mullite phase and promoting the formation of low-temperature eutectic (hercynite and fayalite) resulting in the continuous decrease of AFTs. According to the quantitative calculation of change rate of ash cone height during AFTs test, the melting mechanism was described. Due to the high AFTs of AS0, the ash melting behavior followed the “softening-melting” mechanism; however, for the sample with LR added, the ash melting behavior conformed to the “melting-dissolution” mechanism. Finally, flow temperature (FT) and Tmullite were fitted (FT = 1.35*Tmullite-336.94), and there was a good linear relationship.