干燥强度对褐煤孔隙结构及水分复吸的影响

Drying Intensity Affected to Pore Structure and Water Re-adsorption in Lignite

为考察干燥强度对褐煤孔隙结构及水分复吸的影响,以宝日希勒褐煤为研究对象,在恒温200℃条件下进行了4种不同强度的干燥试验,得到了不同全水分的干燥煤样。采用低温氮吸附法分析了褐煤的孔隙结构特征,并对原煤及不同干燥强度煤样的孔径分布、孔体积和比表面积进行了表征。试验结果表明:在恒温200℃干燥过程中褐煤煤质无明显变化;原煤及不同干燥强度煤样的孔隙结构特征基本一致,等温吸附曲线均属第Ⅱ类,吸附回线均属H3型;随干燥强度的增加,煤样的比表面积先减小后增大,总孔体积和平均孔径逐渐增大。复吸试验结果表明,不同干燥强度煤样的水分复吸量随中孔的增加而增大,选择适宜的干燥强度来减少中孔的增加是抑制褐煤水分复吸的有效途径。

In order to study the drying intensity affected to pore structure and water re- adsorption in lignite,taking Baorixile lignite as the study object,four different drying intensity experiments were conducted at constant temperature 200 ℃,the different dried coal samples with different total moisture were achieved. The low- temperature nitrogen adsorption method was applied to study the pore structure characteristics and the changing features of pore size distribution,pore volume and specific area of raw coal and dried coal samples. The experiment results showed that coal quality did not change significantly during drying process at 200 ℃. The pore structure characteristics of raw coal and different dried coal samples were same. Lignite adsorption isotherm all belonged to type Ⅱ,and adsorption loops all belonged to type H3. With the improvement of drying intensity,specific area decreased firstly and then increased,the total pore volume and average pore size increased gradually. The water re- adsorption experiment results showed that re- adsorption amount increased with the incensement of mesopore. It was an effective way to restrain water re- adsorption amount by choosing appropriate drying intensity to reduce the incensement of mesopore amount.