基于水蒸气吸附模型的低阶煤与高阶煤吸附水特性差异研究

Research on differences of adsorbed water characteristics of low rank and high rank coals based on water vapor adsorption model

掌握煤-水相互作用,对于煤层瓦斯抽采与灾害防治具有重要意义。为此,结合16种水蒸气吸附模型及煤的物化特性分析,开展了低阶煤和高阶煤的水蒸气吸附行为研究。结果表明:改进GAB模型能较好地表征煤吸附水行为,低变质程度长焰煤的第1层饱和吸附能力明显强于高变质程度无烟煤,而2煤样的多层水分子吸附特性差异较小;运用Dent模型和Freundlich模型分析发现,随着湿度的增加,煤吸附水行为是单层吸附、多层吸附、毛细凝聚的依次演变过程;低阶煤与高阶煤的水吸附行为差异与2种煤的含氧官能团数量和孔隙发育程度密切相关。

The coal-water interaction is of great significance for gas extraction and disaster prevention.Combined with 16 water vapor sorption models and the analysis of physicochemical structure of coal samples,the water adsorption behavior of low-rank and high-rank coals was studied.Results show that:the modified GAB model can better characterize the behavior of coal adsorption water,and the single-layer saturated adsorption capacity of low-rank coal samples is higher than that of high-rank coal samples,while there are no obvious differences in multi-layer adsorption capacity for the two samples;based on the Dent and Fre-undlich models,it’s found that with the increasing in water content or relative humidity,the water adsorption mechanism transforms from monolayer,multilayer to condensation successively;the differences in water adsorption behavior between low-rank coal and high rank coal are closely related to the number of oxygen-containing functional groups and the development degree of pore structure.