基于低温DSC的流化床低阶煤干燥临界颗粒尺寸研究

Study on the critical particle size of high moisture low rank coals drying in fluidized-bed reactor via low temperature Differential Scanning Calorimetry(DSC)

低阶煤高水分的特性限制了其应用,从而其脱水是其应用的前提条件,颗粒尺寸对于流化床低阶煤低温烟气干燥能耗及干燥后低阶煤品质具有重要的影响。通过冷态差示扫描量热法(DSC)和发射扫描电子显微镜(SEM)定量分析了不同颗粒尺寸下煤中的水分分布和赋存特性,然后结合小型流化床干燥实验得到了不同大小颗粒的低温烟气干燥特性。研究结果发现,对于不同的低阶煤存在一个干燥临界颗粒尺寸,当颗粒尺寸大于其临界值时,干燥速率和颗粒尺寸几乎没有关系;当颗粒尺寸小于临界值时,随着颗粒尺寸的减小干燥速率增加。样品印尼褐煤的临界颗粒粒径为0.45 mm。

Low rank coals are playing an increasing role in supplying energy,but the property of high moisture content restrains the using of it. When high moisture low rank coal is dried in fluidized bed reactor,the energy consumption and coal quality after drying will be significantly affected by its particles size. In this study,the water form and mass ratio contained in low rank coal particles with different sizes were analyzed using Differential Scanning Calorimetry( DSC) and Scanning Electron Microscope( SEM) Drying experiments were carried out with different particle sizes in a lab scale fluidized bed reactor. It was found for the first time that when the particle is larger than a critical size,the drying rate become almost irrelevant with particle size and when the particle size is smaller than it,the drying rate increases with the particle size decreases. The critical size of the Indonesia lignite tested in this study is 0. 45 mm.