Differences in Gasification Behaviors and Related Properties between Entrained Gasifier Fly Ash and Coal Char

Abstract

In the study, two fly ash samples from Texaco gasifiers were compared to coal char and the physical and chemical properties and reactivity of samples were investigated by scanning electron microscopy (SEM), SEM−energy-dispersive spectrometry (EDS), X-ray diffraction (XRD), N2 and CO2 adsorption method, and isothermal thermogravimetric analysis. The main results were obtained. The carbon content of gasified fly ashes exhibited 31−37%, which was less than the carbon content of 58−59% in the feed coal. The fly ashes exhibited higher Brunauer−Emmett−Teller (BET) surface area, richer meso- and micropores, more disordered carbon crystalline structure, and better CO2 gasification reactivity than coal char. Ashes in fly ashes occurred to agglomerate into larger spherical grains, while those in coal char do not agglomerate. The minerals in fly ashes, especial alkali and alkaline-earth metals, had a catalytic effect on gasification reactivity of fly ash carbon. In the low-temperature range, the gasification process...