月度归档 十月 2020

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Nature of the porosity in American coals

H.Gan, S.P.Nandi, P.L.Walker Jr

Abstract: The nature of the porosity in a number of 40 × 70 (i.e. − 40 + 70) mesh size American coals, varying in rank from anthracite to lignite, has been studied using the following characterization techniques: gas adsorption, helium and mercury displacement, and mercury porosimetry. Surface areas calculated from carbon dioxide adsorption at 298 K are consistently higher than those calculated from nitrogen at 77 K, indicating the molecular sieve character of the coals. Total pore volumes have been measured in the diameter range 12–29 600 Å and then divided into macropores (300-29 600 Å), transitional pores (12–300 Å), and micropores (4–12 Å). Coals vary widely in their total pore volumes (porosities range between 4.1 and 23.2%). In the lower-rank coals (carbon content less than 75%), porosity is primarily due to the presence of macropores. In coals having a carbon content in the range 76–84%, about 80% of the total open pore volume is due to micro and transitional pores, whereas in the coals of higher carbon content microporosity predominates. Coals having about 35–55% of their total open pore volume in the transitional range are expected to be most suitable for use for adsorption of organic molecules from solution. Thus, they are of interest as possible materials to be used in water purification. In general, these results are considered to be of importance in understanding the extent and rate of interaction of coals with gases and liquids.

https://doi.org/10.1016/0016-2361(72)90003-8



Hao Ling 通过Hao Ling

不同煤阶煤样孔隙结构表征及其对瓦斯解吸扩散的影响

李祥春 李忠备 张良 高佳星 聂百胜 孟洋洋

亮点

待更新

摘要:基于气体吸附理论,采用低温液氮吸附法(LT-N2GA),CO2吸附法和扫描电镜法(SEM),从孔容、比表面积、孔径分布和孔隙形状4个方面,研究分析了8种不同变质程度煤样的孔隙结构。并结合煤粒瓦斯扩散实验,计算出煤样的迂曲度和瓦斯扩散通道长度,分析讨论了不同煤阶煤体孔隙结构对瓦斯解吸扩散规律的影响及机理。结果表明:不同煤阶煤样的吸附能力存在显著的差异。随变质程度的加深,吸附能力呈先降低后升高的U形规律;SEM观察结果与低温液氮吸附等温线分析的孔隙形态整体上较为一致,不同煤阶煤样的孔隙形态有很大差异,表明煤体表面的异质性;吸附分析显示中孔孔径呈多峰分布,孔容主要由2~15 nm的中孔贡献;煤体微孔段的吸附能力取决于0.6~0.9 nm和1.5~2.0 nm孔径段。煤质对瓦斯解吸扩散的影响主要与孔隙结构的差异有关。不同煤阶煤体孔隙率和迂曲度不同,瓦斯扩散通道长度不同,随着扩散通道长度的增加,瓦斯初始解吸速率呈指数形式减小;瓦斯在煤体孔隙中的扩散以微孔内的表面扩散为主,孔比表面积越大,表面扩散越显著;瓦斯解吸量和初始扩散系数与煤阶之间呈现不对称U形关系,在高阶煤阶段(Vdaf<15%),随着挥发分的增加,瓦斯解吸量和初始扩散系数显著减小。在中、低阶煤阶段(Vdaf>15%),随着挥发分的增加,二者缓慢增加。

关键词:煤阶 孔隙结构表征 微孔 扩散通道 瓦斯解吸扩散规律

http://doi.org/10.13225/j.cnki.jccs.2018.1374


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瓦斯抽采钻孔封孔材料、工艺、理论

瓦斯抽采是瓦斯治理的重要手段,瓦斯抽采主要依靠打钻和封孔来完成,而封孔是瓦斯抽采的重要环节,其中封孔深度对于瓦斯抽采具有重要影响。