Abstract: There exists blocking in real gasification process of Yulin coal in whose ash the content of calcium and sulfur is high.The large fluctuation of viscosity-temperature curve measured in laboratory can be observed.FactSage 6.2 software was used to calculate ternary phase equilibrium and phase change rules during ash melting of Yulin coal under different ranges of high temperature.Based on these results and XRD measurement, the characteristics of ash fusion and viscosity-temperature changes caused by the addition of SiO₂ as well as the reason of viscosity fluctuation were analyzed.The results show that the fusion temperature of Yulin coal ash decreased initially then increased with the increasing values of SiO₂/Al₂O₃（S/A） and acid/base（A/B）.There is a strong correlation between the formation of gehlenite and viscosity fluctuation within certain temperature ranges.The viscosity fluctuation of Yulin coal ash can be alleviated by adding appropriate SiO₂(to the point when S/A=2.48), its amount can be obtained from binary phase diagrams calculated by FactSage.The numerical calculation results are in agreement with the experimental data, which proves that the chemical thermodynamic equilibrium analysis method is suitable for investigating the characteristics of ash melting.

Key words: Yulin coal, viscosity-temperature characteristic, fusion characteristic

摘要： 榆林煤灰分中钙、硫含量均很高，气流床气化过程中存在易于结渣的问题，实验室测量其黏温曲线波动性很大。 采用FactSage6.2软件计算三元平衡相图和煤灰高温熔融过程的物相变化规律，并结合XRD手段，分析了加入SiO₂引起的煤灰熔融特性和黏温特性改变的机理以及黏度波动的原因。结果表明，榆林煤灰熔点随着硅铝比（S/A）、酸碱比（A/B）的增大先降低后升高；钙铝黄长石与煤灰黏温曲线波动性有较强关联，通过FactSage二元相图得出，加入SiO₂至S/A=2.48可减小曲线波动性。FactSage数值计算结果与实验结果吻合良好，表明化学热力学反应平衡分析方法是研究灰渣熔融特性的一种有效手段。

关键词: 榆林煤, 黏温特性, 熔融特性