Experimental and kinetic study of steam gasification of low-rank coal in molten blast furnace slag

Abstract

In this study, the isothermal tests for steam gasification of Dezhou (DZ) low-rank coal with molten blast furnace slag (BFS) were performed in a lab-scale continuous gasification system, to investigate the status of gasification and syngas production. The results showed that molten BFS provided the heat needed for gasification reaction to ensure gasification is successful. The carbon conversion efficiency (CE), cold gasification efficiency (CGE) and percentage of combustible gas were higher than 85%, 100% and 87%, respectively. Meanwhile, thermo-gravimetric kinetic experiments were conducted to obtain the role of BFS in low-rank coal gasification. The study found that carbon conversion at a certain time was significantly enhanced with BFS as heat carrier. The reactivity index of coal was also improved under this condition. The reactivity index of coal with steam to coal (S/C) ratio of 1:2 was approximately 1.98 times higher than that with S/C ratio of 1:0 at 1673 K. The most probable kinetic mechanism model of DZ low-rank coal turned from D2 model to A2 model. Not only was BFS the heat carrier, but also it was the active catalyst in low-rank coal gasification. Eventually, the catalytic mechanism of coal gasification using BFS as heat carrier was schematically proposed.