高温高压吸附后焦煤的孔隙结构变化特性

Pore structure changing features of the coking coal due to the adsorption of high temperature and high pressure

为研究高温高压气体吸附试验中焦煤基质膨胀后孔隙结构变化特性,首先开展了软、硬焦煤在不同吸附平衡温度(30℃、40℃、50℃)下的高温高压吸附试验,然后利用压汞法测试吸附试验前、后煤样的孔隙结构,研究了不同吸附平衡温度下的软、硬焦煤吸附性能及高温高压吸附试验对软、硬煤孔隙结构的影响。结果表明:在相同温度和压力下,硬煤瓦斯吸附量及吸附常数a均小于相应的软煤;随吸附平衡温度升高,同一煤样的瓦斯吸附量减少;高温高压吸附试验后,煤样含有大量的半封闭型的微孔和小孔,孔隙连通性变差,煤中孔隙向着更加致密的方向发展,有利于瓦斯的储存。

This article intends to cherish our wishes to share out our study findings on the coal’s pore structure changing features as a result of the experiment due to the high temperature and high pressure adsorption.To achieve the said goal,we have managed to carry out the adsorption experiments of the soft and hard coking coal at the different temperatures(say,30 ℃,40 ℃,and 50 ℃).And,then,we have managed to test the pore structure of the raw coal and coal samples through different adsorption experiments by using the mercury injection method.And,then,the adsorption constants a and b of the soft and hard coking coal have been tested at the different temperatures,while examining the gas adsorption properties of the different coal samples.At the same time,we have also analyzed the pore structure change of the coal samples after the high temprature and high pressure adsorption experiments.The results of our experimental investigations demonstrate that the coal samples have to undergo some certain deformation in the gas adsorption process.And,in turn,it has also been made possible for us to notice that the adsorption capacity and the adsorption constant a of the hard coal has been found smaller than those of the corresponding soft coal under the same temperature and pressure.In addition,there can also be found that the gas adsorption amount of the same coal sample has been decreasing with the increase of the adsorption temperature.And,simultaneously,the coal sample contains large numbers of semi-closed micro-pores and mini-pores through the high temperature and pressure adsorption,so as for the pore connectivity to get worse or looser.And,consequently,through the reaction to the high temperature and high pressure,the volume of the visible holes and crack holes of the coal sample may tend to decrease,whilst the proportion of the pore volume in the big hole stage would begin to increase.In addition,the specific surface areas of the coal samples also increase due to the adsorption at high temperature and pressure.And,then,when the pressure remains constant,the specific surface area of the coal measured by the mercury injection method may tend to decreases with the increase of the temperature.And,above all,the pores inside the coal powder themselves may tend to evolve or develop towards a more compact direction,which has been proven to be favorable for the gas storage.