Experiment study on entrained flow gasification technology with dry slag by second-stage water supply

Experimental system of a new entrained flow gasifier with second-stage water supply (20kg/h) was set up in this paper, and effect of molar ratio of O/C on temperature distribution, syngas composition, carbon conversion and effective syngas were analyzed with a typical high AFT coal (Guizhou LJ coal). The results of non-second-stage water and second-stage water with changing molar ratio of O/C indicate that, when the molar ratio of O/C is larger than 0.96, gasification efficiency with dry slag by second-stage water would become better than non-second-stage water. Specifically, when the molar ratio of O/C was 1.1, the effective syngas fraction and carbon conversion of second-stage water gasification were 80.2% and 93.24% respectively. Correspondingly, the effective syngas fraction and carbon conversion of non-second-stage water gasification were 78.5% and 91.67% respectively. Furthermore, the gasification temperature was lower than the ash fusion temperature of test sample, the slag was non-melt during all the gasification experiments. The optimal gasification was conducted with the process temperature under 1450°C, which was lower than the ash fusion temperature of LJ coal. These experimental results prove the applicability of entrained flow gasification technology with dry slag by second-stage water supply on using high AFT coals, which is helpful to generalize the large-scale gasification technology using abundant high AFT coals in China. [Display omitted] •We construct a 20kg/h entrained flow gasifier by second-stage water supply.•The dry slag is ensured by adjusting the oxygen and H2O in two-stage.•Increasing O/C molar ratio will increase carbon conversion and CO+H2 fraction.•Gasification with second-stage water performs better for O/C molar ratio above 0.96.