CaCO_3对煤灰熔融特性和黏温特性影响的研究

Effects of CaCO_3 on the Fusion Characteristic and Viscosity-temperature Behaviour of Coal Ashes

为研究CaCO3在高温条件下对高灰熔点煤灰的熔融特性和黏温特性的影响,试验选取已应用于气流床气化装置的煤样A、B和C为原料,分别利用灰熔点仪和高温黏度计对添加CaCO3的煤灰样品进行熔融特性和黏温特性测量,并采用热力学计算软件FactSage 6.1中的Phase Diagram和Equilib模块进行热力学平衡计算。结果表明,Al2O3和SiO2含量较高的煤灰样品在熔融的过程中产生大量的莫来石,导致其灰熔点较高。CaCO3的添加可以有效抑制莫来石的生成,改变高温下煤灰中主固相物质的类型,降低固相物质的百分含量,降低煤灰的全液相温度,从而达到降低煤灰熔融性温度和黏度以及改变渣型的效果。数值计算的结果与试验结果基本一致,表明化学热力学反应平衡分析方法是研究灰渣熔融特性和黏温特性一种有效手段。

In this paper,the effect of CaCO3 on the fusion characteristic and viscosity-temperature behavior of coal ashes was studied.Three coal samples applied in entrained flow gasification plant in China,including coal A,B,and C were prepared as raw materials for the ash fusion temperature（AFT） and viscosity tests.The thermodynamic equilibrium modeling was carried out using Phase Diagram and Equilib modules of FactSage 6.1 software.The results indicate that a large amount of mullite forms in the coal ash samples with high levels of Al2O3 and SiO2 in the melting process.It is the main reason for the high ash fusion temperature.CaCO3 can effectively suppress the formation of mullite,change the type of main solid phases in ash samples,reduce the percentage content of solid phases and reduce the liquids temperature.The addition of CaCO3 can achieve the purpose of reducing the ash fusion temperature and viscosity values,and changing the type of the slag.Numerical results consistent with the experimental results,indicating that the equilibrium thermodynamic analysis is a practical and effective measure to study the fusion characteristic and viscosity-temperature behavior of coal ashes.