Comparison study of fusibility between coal ash and synthetic ash

Abstract Coal ash fusibility plays an essential role in selecting coal and determining operation condition for different gasifiers. To understand main factors on ash fusibility for adjustment, the synthetic ash which composed of pure oxides is widely used in previous study instead of the real coal ash. However, the comparison on fusibility between coal ash (CA) and synthetic ash (SA) is still unknown. In this study, four typical coals were selected to compare fusibility between CA and SA. The results indicated that the SA is not suitable to simulate all CA for fusibility study. For the ash with high-calcium-low-iron, SA can be used because of the same mineral transformation at high temperatures. The AFTs of the ash with high-calcium-high(medium)-iron is higher than that of SA, resulting from difference between gehlenite and akermanite. Mullite is detected in CA with low-calcium-low-iron, so the SA cannot replace CA to investigate fusibility for absence of mullite. Besides, fusibility of samples with low liquid content and high viscosity of liquid cannot be simulated by synthetic ash due to different mass transfer rate. The ashes with chemical compositions located in high-melting-temperature region shows an obvious different fusibility between CA and SA because of the low liquid content.