干燥时间对褐煤孔结构变化及其复吸行为的影响

Effect of Drying Time on the Change of Pore Structure and Re-adsorption Behavior of Lignite

为了探讨褐煤干燥过程中孔结构的变化及其与水分复吸的关联,选择平庄褐煤为研究对象,进行了不同温度和干燥时间条件下,褐煤的干燥、干燥煤的复吸及孔结构变化的实验研究。结果表明:干燥时间对褐煤干燥行为及其复吸能力的影响主要与其孔结构的变化有关,该作用在很大程度上也受干燥温度的控制;不同程度干燥煤的复吸结果显示,褐煤在不同温度常压惰性气氛下的干燥存在一相同的最佳时间(本实验条件下为20min)。在褐煤干燥过程中伴随孔结构的变化,比表面积和大孔体积的减小以及中孔体积的增大是一个渐进过程。中孔结构的变化是影响褐煤复吸的主要因素,在干燥过程中通过优化操作条件调控中孔结构的变化是抑制褐煤复吸的一个有效途径。

In order to investigate the relationship between the change of pore structure and re- adsorption behavior during lignite drying, a series of studies were carried out at different drying time and temperature. The results show that the effect of drying time on the drying behavior of lignite and its ability of re-adsorbing moisture varied with pore structure of dewatering coal, in which the drying temperature was dominant to a large extent. The re-adsorption behavior and ef- ficiency of moisture removing from lignite show that there was a similar optimum drying time （20 rain in this experiment） at different drying temperature in the inert atmosphere under atmospheric pressure. The change of pore structure in the drying process of lignite （namely, the decrease of specific surface area and macropore volume, the increase of mesopore volume） was a gradual process. The mesopore structure in lignite was the main factor influencing its capacity of re-ad- sorbing moisture, therefore regulating the mesopore structure by optimizing the operating condi- tions is an effective way to restrain drying lignite re-adsorption.