锡盟褐煤干燥和重吸收特性的实验研究

Experimental Study on Drying and Reabsorption of the Lignite of Ximeng

针对内蒙古的锡盟褐煤,采用快速水分干燥仪模拟恒温蒸发干燥过程。利用扫描电镜测试发现干燥后的煤样表面形貌有所变化,出现断裂、粉化等现象。选择不同的干燥温度（70、100、120℃）、粒径（0.5~0.6、0.6~1.6、1.6~4 mm）、干燥时间（2、3.5、9、30 min）研究该褐煤的干燥和重吸收特性。发现干燥过程主要受温度、粒径的影响;而重吸收水分主要取决于最终水分含量、孔隙结构的破坏情况、粒径和环境湿度变化。将干燥过程的实验数据与常用的干燥方程进行拟合,其中Modified Henderson and Pabis模型拟合效果最好。并应用Fick扩散模型和Arrhenius经验公式计算得到该褐煤恒温蒸发干燥过程的有效扩散系数和活化能。

The rapid moisture-determining instrument was used to simulate the process of constant temperature drying on the lignite of Ximeng from the Inner Mongolia. By using the scanning electron, microscope （SEM）, it was observed that the surface morphology of dried coal is changed, such as breaking down and pulverization. Different drying temperatures （70, 100, 120 ~C）, particle sizes （0.5-0.6, 0.6-1.6, 1.6-4mm）, and drying time （2, 3.5, 9, 30min） were chosen to study the features of drying and reabsorption of the lignite. The results show that the drying process is mostly affected by the particle size and temperature; the reabsorption amount of water mainly depends on the moisture of the dried coal, the damage of the void structure, the particle size and the variation of the environment humidity. Among common thin layer drying models, Modified Henderson and Pabis model shows the better predictions. At the same time, the effective diffusivity coefficient and the activated energy for the moisture diffusion are calculated by applying the Fick＇s diffusion model and Arrhenius type relationship.