基于-1H-NMR的胜利褐煤原位低温干燥过程中弛豫时间及孔结构变化  

Relaxation time and pore structure evolution of Shengli lignite during in situ low temperature drying using -1H-NMR

作　　者：滕英跃[1,2] 廉士俊 宋银敏[1,2] 刘全生[1,2] 余海燕[1,2] 李阳[1,2] 智科端[1,2] 张永强[3] 

机构地区：[1]内蒙古工业大学化工学院,内蒙古呼和浩特010051 [2]内蒙古工业大学内蒙古自治区工业催化重点实验室,内蒙古呼和浩特010051 [3]内蒙古科技大学化学与化工学院,内蒙古包头014010

出　　处：《煤炭学报》2014年第12期2525-2530,共6页Journal of China Coal Society

基　　金：国家自然科学基金资助项目(21066008;21266017);包头市科技计划资助项目(2013J2001-4)

摘　　要：传统煤水分测定对煤样有破坏,同时BET法在煤孔结构测试中也遇到许多困难。利用1H-NMR研究褐煤低温干燥过程中水分赋存状态及孔结构变化,包括原位干燥过程中褐煤水分横向弛豫时间T2的动态发展及孔结构变化规律。结果表明:空气自然干燥状态下,胜利褐煤中不冻水和束缚水占绝大多数,其中束缚水结合力较弱。在50℃前,部分束缚水较易脱附;干燥后冷却样品中残余水的束缚性随处理温度的升高而增加;105℃干燥脱水后,微孔增加,中孔比例减少,大孔或裂隙增加,残余水分保留在10 nm以下孔隙中,为不冻水;此时含水孔隙仅占全部孔隙的19%,远小于原煤(58%)。1H-NMR可以在无损伤情况下连续监测煤中水分、孔结构的分布变化,更适用于煤水分及孔结构的测定。Traditional methods to characterize the moisture in coals have to damage coal samples,and there are many difficulties in the application of BET method to test the pore structure of coals. The moisture occurrence state and pore structure evolution of lignite in low temperature drying process were investigated by means of1H-NMR,specifically including the dynamic development of the transverse relaxation time T2 of lignite moisture during in situ drying process and the varying patterns of pores distribution. The results show that the non-freezing water and bound water account for main part of the moisture in Shengli lignite during natural drying. The binding force of bound water is weak,part of which could be desorbed easily below 50 ℃. After being dried,the binding of moisture in coal samples rises with the increase of temperature. The proportion of mesopores decreases after being low temperature dried and dehydrated at105 ℃,at the same time,the micropore and macropores or cracks increase,and the moisture leaves,mainly non-freezing water stays in the pores of less than 10 nm. At this point,the pores containing moisture only account for 19% of all pores,much less than that of raw coal,58%. The1H-NMR is an efficient tool for continuously monitoring the change of pore size distribution and the moisture of coals. Therefore,the 1H-NMR is especially practical for characterizing the moisture occurrence state and pore structure of coals.

关 键 词：低场核磁共振(1H-NMR) 褐煤 低温干燥 弛豫时间 孔结构 

分 类 号：TD849.2[矿业工程—煤矿开采]