Transcripción del resumen del autor. To investigate the formation mechanism of slag and prevent its occurrence during lignite fluid-bed gasification, mixed samples of graphite and 450 °C Xiaolongtan (XLT) ashes (1:19, mass ratio, MA) treated with different temperatures were prepared. The samples and the block slag formed during the tests of XLT ash agglomeration fluid-bed (AFB) pilot-scale gasification were examined by chemical composition, scanning electron microscope with energy dispersive X-ray detector (SEM-EDX), and X-ray diffraction (XRD) analyses. The results show the elements of iron and silicon are enriched in the slag due to the adherence of low-melting-point ferro-silicate. The interactions of the mineral matter in MA formed the same kinds of mineral crystals as those in the slag under reducing atmosphere (CO2/H2 = 1:1) at 950 °C. The formation mechanism of slag is proposed by the generation of adhesive glassy material, the formation of partial melting entities, the substitution of the iron in liquid aluminate or aluminosilicate by calcium and the mergence of individual particles. Pilot-scale AFB tests indicate that the reduction of operating temperature to 850-930 °C by increasing steam/oxygen ratio can successfully prevent slag problems during XLT AFB gasification.

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