不同气体组分条件下煤灰颗粒熔融特性研究

Study on melting characteristics of coal ash particles in different atmospheres

为掌握气体组分对灰熔融特性的影响规律,探究矿物转变对灰熔融特性的影响,利用高温热台显微镜,对神府煤灰、神华煤灰和神木煤灰在高温CO_(2),N_(2)和空气条件下,以10℃/min,50℃/min和100℃/min升温速率的熔融过程收缩性进行了原位可视化研究。利用热力学计算等方法研究了不同气体组分条件下实验煤灰熔融过程的矿物质变化。结果表明:升温速率对煤灰熔融过程面积收缩的影响大于气体组分对煤灰熔融过程面积收缩的影响,煤灰收缩性随着升温速率降低而增强;升温速率相同,神府煤灰、神华煤灰和神木煤灰在CO_(2)条件下的收缩性均强于空气和N_(2)条件下的收缩性,神府煤灰对CO_(2)敏感性最强,收缩率为21.70%,而在N2和空气条件下的收缩率分别为17.12%和16.58%;相同气体组分下,神木煤灰在10℃/min升温速率下收缩率最大,可至32.36%。高温下神木煤灰的收缩主要受钠长石影响,神木煤灰的收缩性强于神府煤灰和神华煤灰的收缩性,原因在于高温下钠长石的收缩性强于钙长石和斜辉石的收缩性。

In order to grasp the law of influence of gas components on ash melting characteristics and to understand the influence of mineral transformation on ash melting characteristics,in this research,a high-temperature hot stage microscopy was employed to conduct in-situ visualization studies on the shrinkage of Shenfu coal ash,Shenhua coal ash and Shenmu coal ash under high temperature CO_(2),N_(2) and air conditions at different heating rates(10℃/min,50℃/min and 100℃/min).The mineral transformations during the melting process of experimental coal ashes in different gas compositions were evaluated using thermodynamic calculations and other methods.The results indicate that the effect of heating rate on the area shrinkage of coal ash during the melting process is more prominent than that of gas components,and the shrinkage increases with decreasing heating rate.At the same heating rate,the shrinkage of coal ash under CO_(2) conditions is stronger than that under air and N_(2) conditions.Among the three types of coal ash,Shenfu coal ash is the most responsive to CO_(2),with a shrinkage rate of 21.70%,whereas the shrinkage rates under N2 and air conditions are 17.12% and 16.58%,respectively.In the same gas composition,Shenmu coal ash has the highest shrinkage rate at a heating rate of 10℃/min,which can be up to 32.36%.At high temperatures,the shrinkage of Shenmu coal ash is mainly affected by albite,which exhibits greater shrinkage than anorthite and clinopyroxene,thereby explaining why the shrinkage of Shenmu coal ash exceeds that of Shenfu coal ash and Shenhua coal ash.