The entrained flow gasification is becoming a predominant and efficient way for coal clean utilization. And the steady and reliable removal of the ash slag is the key factor for smooth operation of entrained gasifiers. For the purpose of reducing the additive amount of flux and improving gasification efficiency, the influence of CaO/Fe2O3 (weight ratio of CaO/Fe2O3) on the viscositytemperature behavior was studied in this work. Slag structure at high temperatures, and crystallization behavior of the coal ash slag with different CaO/Fe2O3 were studied in detail. As the CaO/Fe2O3 of the slag decreased, viscosity of the slag decreased at same temperatures. And Fe2O3 has a more decreasing effect on slag viscosity compared with CaO. Si-O-Si proportion is the key factor to influence slag viscosity when CaO/Fe2O3 is over 6:4, for other CaO/Fe2O3, Al-O structure should be considered. Both positive and negative mutual effect exist between CaO and Fe2O3. When CaO/Fe2O3 is lower than 2:8, they have negative mutual effect for breaking Si-O-Si bond. In addition, Sample 10C0F and 2C8F are suitable for the smooth operation of entrained flow gasification.
Keywords Entrained flow gasification; Slag viscosity behavior; CaO/Fe2O3; Network structure; Crystallization