炼焦煤显微结构在热转化过程中的变化规律研究

Research on changes in the microstructure of coking coal during thermal conversion process

深入研究炼焦煤显微组分在热转化过程中的变化规律,对揭示焦炭光学组织的形成过程和优化配煤结构具有重要意义。利用煤岩学研究方法系统研究3种典型焦煤的煤质与岩相特征、焦炭光学组织特性、镜质体反射率分布对光学组织的影响以及焦炭光学组织在热转化过程中的演变规律。结果表明:焦炭的反应后强度与其粗粒镶嵌、纤维状和片状组织的含量呈正相关关系。3种焦煤的镜质体反射率区间0.95%~1.35%含量大小为JM-3>JM-2>JM-1,>1.35%区间的含量关系是JM-1>JM-2>JM-3,仅从煤的镜质体反射率区间分布情况还不能准确预测焦炭的质量。在胶质体软化熔融阶段以各向同性组织和丝质及破片为主。随着热解温度的升高,煤中的各向同性组织含量大幅降低,镜质组等活性组分逐渐发生反应、熔融等形成镶嵌类、纤维状和片状组织。焦炭中的镶嵌类和纤维状光学组织主要形成于高温下的焦炭缩聚反应阶段,在该反应过程中丝质及破片类组织中的部分活性组分继续发生转化形成镶嵌类组织。

Thoroughly studying the changes in the microstructure of coking coal during thermal conversion is of great significance for revealing the formation process of coke optical structure and optimizing coal blending structure.A systematic study was conducted using coal petrology research methods to investigate the coal quality and lithofacies characteristics of three typical coking coals,the optical microstructure characteristics of coke,the influence of vitrinite reflectance distribution on optical microstructure,and the evolution law of coke optical microstructure during thermal conversion.The results indicate that the strength of coke after reaction is positively correlated with the content of coarse mosaic texture,fibrous and leaflet texture.The content range of three types of coking coal’s vitrinite reflectance is 0.95%-1.35%,with JM-3>JM-2>JM-1.The content relationship in the range of>1.35%is JM-1>JM-2>JM-3.It is not accurate to predict the quality of coke solely based on the distribution of vitrinite reflectance range in coal.During the softening and melting stage of the metaplast,isotropic texture,fusinite and frag mental texture are the main components.As the pyrolysis temperature increases,the content of isotropic texture in coal decreases significantly,and active components such as vitrinite gradually react and melt to form mosaic,fibrous,and leaflet texture.The mosaic and fibrous optical structures in coke are mainly formed during the high temperature coke condensation reaction stage,during which some active components in the fusinite and frag mental texture continue to undergo transformation to form mosaic texture.