Micro-pores and fractures of coals analysed by field emission scanning electron microscopy and fractal theory
Micro-pores and fractures of coals analysed by field emission scanning electron microscopy and fractal theory
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场发射扫描电镜和分形理论分析煤的微观孔隙和裂隙
DOI：
10.1016/j.fuel.2015.10.011
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发表时间：
2016-01-15
期刊：
影响因子：
7.4
通讯作者：
Ji, Zhongmin
中科院分区：
文献类型：
--
作者：
Pan, Jienan;Wang, Kai;Ji, Zhongmin
利用场发射扫描电镜（FESEM）对6个不同变质程度（Ro，Rm = 0.75-2.80%）煤样的显微孔隙和裂隙进行了分析。基于分形理论对微裂缝和孔隙进行了定量分类。结果表明，根据分形理论，煤基质中的孔隙可以分为微孔隙和微裂隙。微孔呈现圆形或椭圆形，而微裂缝弯曲并呈现不规则形状，其通过圆形或椭圆形通道与其他微裂缝连接。随着变质程度的增加，微孔隙和微裂缝的总表面孔隙度分布呈倒“U”形。总的表面孔隙度是在其最大的高阶烟煤阶段。但煤变质程度与微孔隙和微裂隙面密度的相关性各不相同。在低、中煤阶阶段，微孔隙和裂隙的表面频率和平均宽度随煤阶的增加而增加。在高煤阶阶段，随着煤阶的增加，微孔隙和裂隙的表面频率迅速增加，但总体上低于低、中煤阶阶段。微裂缝的平均宽度随着平均表面频率的增加呈对数关系减小;相反，微孔的平均宽度随着平均表面频率的增加呈对数关系增加。(C)2015爱思唯尔有限公司版权所有。
In this study, the micro-pores and fractures of six coal samples with different metamorphic degrees (R-o,R-m = 0.75-2.80%) were analysed using field emission scanning electron microscopy (FESEM). The micro-fractures and pores were quantitatively classified based on fractal theory. Our results show that pores in coal matrix can be categorised as either micro-pores or micro-fractures according to fractal theory. Micro-pores exhibit round or elliptical shapes, whereas micro-fractures are bent and exhibit irregular shapes, which are connected with other micro-fractures via round or elliptical channels. With increasing metamorphic degrees, the distribution of the total surface porosity of micro-pores and micro-fractures is characterised by an inverted "U" shape. The total surface porosity is at its greatest during the high-rank bituminous coal stage. However, the correlation between coal metamorphic degree and surface densities of micro-pores and micro-fractures varies. During the low- and medium-rank stages, the surface frequency and the average width of micro-pores and fractures increase with increasing coal rank. During the high-rank coal stage, with increasing coal rank, the surface frequency of micro-pores and fractures rapidly increases but as a whole is lower than those during the low- and medium-rank stages. The average width of micro-fractures decreases with increasing average surface frequency in a logarithmic relationship; in contrast, the average width of micro-pores increases logarithmically with increasing average surface frequency. (C) 2015 Elsevier Ltd. All rights reserved.