INFLUENCE OF NATURAL MOISTURE ON THE CHARACTERISTIC TIME OF METHANE DESORPTION FROM COALS OF VARIOUS DEGREES OF METAMORPHISM

V. Vasylkivskyi, L. Stefanovich, O. Chesnokova
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Abstract

Goal. To study the effect of natural internal moisture content on the kinetics of methane desorption from coals of varying degrees of metamorphization. Methodology. For the research, coal was used after a long (more than 100 days) preliminary exposure in a dry, closed indoors. The measurements were carried out on several samples of Donbass coals with different volatile content. Two groups of coal samples were used - dry, with natural internal humidity and one sample with artificial humidity of 1.5%. The volumetric method was used for measurements. The method includes three stages: 1st  saturation of coal with compressed methane, 2nd  preliminary discharge of compressed gas from a container with coal after its saturation, and 3rd  collection of methane released by coal into a storage vessel. Before registration of desorption, pressurized gas was discharged from the free volume of containers into the atmosphere. The desorption unit contains a low-temperature trap (78°C) for water vapor and a warming radiator for methane entering the storage vessel. To determine the numerical values of the characteristic time of desorption of methane from coal, we used information on the change in gas pressure in the storage vessel during desorption. To analyze the results, a method based on the concept of a change in the characteristic relaxation time of desorption during methane emission was used. Results. Experimental results show that in wet coals the ratio between the amount of methane in coal and the intensity of its outflow at any desorption site is less than in dry coals. It was found that in coals of the metamorphic series the presence of natural moisture leads to a decrease in the intensity of methane emission, a decrease in the characteristic desorption time and a decrease in the activation energy of methane desorption by 0.4 - 2.5 kJ / mol. The features of the kinetics of desorption indicates competition energetics of interactions between methane and water with the surface of the pores of coal. Scientific novelty. It was found that even without artificial humidification, but in the presence of natural internal moisture in coal, the degassing time during desorption is reduced (in comparison with dry coal). Practical significance. The research results can be used to optimize the duration of hydraulic saturation of the coal seam and the water consumption during coal degassing.
自然水分对不同变质程度煤甲烷解吸特征时间的影响
的目标。研究不同变质程度煤内部天然含水率对甲烷解吸动力学的影响。方法。在这项研究中,煤是在干燥、封闭的室内长期(超过100天)暴露后使用的。对几种不同挥发分含量的顿巴斯煤样品进行了测量。采用两组煤样,一组为自然内部湿度的干燥煤样,另一组为1.5%的人工湿度煤样。采用体积法进行测量。该方法包括三个阶段:第一步使煤用压缩甲烷饱和,第二步使压缩气体从煤饱和后的容器中初步排出,第三步将煤释放的甲烷收集到储存容器中。在登记解吸前,加压气体从容器的自由容积排放到大气中。解吸装置包含一个用于水蒸气的低温捕集器(78°C)和一个用于进入储存容器的甲烷的加热散热器。为了确定煤中甲烷解吸特征时间的数值,我们使用了解吸过程中储存容器内气体压力变化的信息。为了分析结果,采用了一种基于甲烷释放过程中解吸特征弛豫时间变化概念的方法。结果。实验结果表明,湿煤中任一解吸部位的甲烷含量与甲烷流出强度之比均小于干煤。研究发现,在变质系煤中,天然水分的存在使甲烷释放强度降低,特征解吸时间缩短,甲烷解吸活化能降低0.4 ~ 2.5 kJ / mol。解吸动力学特征表明甲烷和水与煤孔隙表面相互作用的竞争能量学。科学的新奇。研究发现,即使没有人工加湿,但在煤中存在自然内部水分的情况下,解吸过程中的脱气时间也缩短了(与干煤相比)。现实意义。研究结果可用于优化煤层水力饱和持续时间和煤脱气过程的耗水量。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
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