贵州珠藏向斜无烟煤孔隙结构特征及其对吸附性的影响

Pore property and its impact on the coalbed methane adsorption of anthracite from Zhu-Zang syncline, Guizhou Province

  • 摘要: 通过压汞、液氮吸附实验对贵州珠藏向斜无烟煤孔隙结构特征进行研究,根据实验结果分析孔隙结构特征,并结合等温吸附试验,探讨了煤孔隙结构特征对其吸附性的影响。结果表明:珠藏向斜无烟煤主要以微孔、小孔为主,比表面积主要由微孔控制;“孔隙遮挡效应理论”能够很好地解释低退汞效率、高滞后环现象;由于测试原理不同,液氮、压汞实验结果有较大差异;研究区Langmuir体积平均为36.70 m3/t,Langmuir压力平均为3.23 MPa,Langmuir体积、Langmuir压力与微孔比表面积、退汞效率均呈现正相关;另外,Langmuir压力受微孔结构影响较大,特别是封闭孔的含量,封闭孔越多,Langmuir压力越高。

     

    Abstract: T Based on the result from the mercury intrusion analyses and low temperature nitrogen adsorption/desorption, the property of pore system of anthracite in Zhu-Zang syncline was analyzed systematically. Combined with isothermal adsorption test, the effect of pore structure on adsorption characteristics had been discussed. The research show that pores in the samples are dominated by micro-pores and the specific surface area mainly comes from the micro-pores. There is a hysteresis loop between the mercury intrusion and extrusion curves and the hysteresis loop did not close when the imposed pressure was reduced back to ambient. The hysteresis behavior and entrapment of mercury can be explained by the pore shielding effect. The result of mercury intrusion is higher than low temperature nitrogen adsorption/desorption due to entire difference in the experimental principles. Langmuir equation was used to characterize the adsorption characteristics of anthracite. The average value of Langmuir volume was 36.70 m3/t, the average value of Langmuir pressure was 3.23 MPa. Langmuir volume and Langmuir pressure increased with the micro-pore surface area and the efficiency of mercury ejection. Additionally, Langmuir pressure seems to be quite sensitive to micro-pore structure. An increase in closed pore leads higher Langmuir pressure.

     

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