褐煤脱水提质是其大规模利用的前提。水热提质是一种非蒸发干燥技术，具有节能降耗的优势。对褐煤提质过程中不同赋存形态水分的脱除、分布情况及提质煤水分复吸行为进行研究可为褐煤高效水热提质提供理论指导。采用水热法对我国内蒙古褐煤和云南褐煤进行脱水提质，通过等温干燥法测定了原煤及水热提质煤样中的水分和类型，运用化学滴定和氮吸附法分别测试了煤样含氧基团和孔结构，考察了水热提质对褐煤水分分布的影响;在30 ℃下进行煤样水分等温吸附测试，使用修正BET模型探讨了不同水热提质煤样的水分吸附行为。结果表明，水热提质降低了内蒙古褐煤和云南褐煤中的含水率，包括分子水、毛细水和自由水的含水率，其中分子水脱除率更高。水热提质脱除褐煤中的水分主要通过分解褐煤中亲水性含氧基团，使得所含分子水显著降低，同时毛细水和自由水也不同程度减少。提质褐煤含氧基团的减少和孔结构的变化分别影响提质煤的第1类水分(与含氧基团以强氢键结合的水分)和第2类水分(多层吸附和毛细冷凝吸附的水分)的吸附量。与内蒙古褐煤相比，煤阶较低的云南褐煤在水热提质过程中脱除了更多水分，其第1类和第2类水分吸附量降低更为显著，说明水热提质更适用于高含水的低阶褐煤。

Dewatering and upgrading are the premise of large scale utilization of lignite.Hydrothermal de watering (HTD) is a non evaporative drying technology,which has advantages of energy conservation and consumption reduction.In order to provide a theoretical guidance for the HTD of lignite,it is of importance to investigate the removal behavior and distribution of different types of water in lignite and the water re absorption behavior of upgraded lignite.Two lignite samples from Inner Mongolia and Yunnan provinces in China were upgraded by the HTD method.Water contents and types in the raw lignite and the HTD coal samples were determined by isothermal drying method.The oxygen functional groups and pore structures of coal samples were characterized using the chemical titration and N2 adsorption methods to investigate the effect of HTD on water distribution in lignite.Moreover,the water adsorption isotherms of the HTD coal samples were obtained at 30 ℃ and analyzed by the modified BET model.The results showed that the HTD process removed mainly molecular water,and partly capillary water and free water in lignite by decomposing oxygen functional groups.The removal of oxygen functional groups and change of pore structures in the HTD coal samples affected the primary adsorption capacity for water (combined with oxygen functional groups by hydrogen bonds) and secondary adsorption capacity for water (adsorbed in multilayer and capillary condensation) respectively.In the HTD process,the water in lower rank Yunnan lignite was removed more,and the reductions of primary and secondary adsorption capacities for water were more remarkable compared with Inner Mongolia lignite.It implied that the HTD process was more suitable for lower rank lignite with high water content.

1 实验部分

   1.1 原料

   1.2 褐煤的水热提质

   1.3 煤样的水分测定

   1.4 提质煤的水分等温吸附

   1.5 样品的表征

2 结果与讨论

   2.1 水热提质褐煤中水分的分布

   2.2 水热提质褐煤的水分吸附行为

3 结论