单颗粒褐煤高温烟气干燥过程实验研究

EXPERIMENTAL STUDY ON SINGLE LIGNITE PARTICLE DRYING PROCESS BY HOT FLUE GAS

针对10mm^25mm粒径的大唐五间房褐煤,通过单颗粒高温烟气干燥实验,得到了600℃~900℃烟气温度下的干燥特性曲线,研究了干燥介质温度和粒径对褐煤高温脱水效果的影响,发现干燥过程主要处于降速干燥阶段;高温条件下,温度对干燥速率的影响并不显著;针对褐煤水分在干燥过程中的迁移特点以及大唐五间房褐煤的孔隙特征,基于努森扩散定律,建立了水分蒸发为蒸汽再扩散出煤粒的缩核干燥动力学模型;得到了不同温度下的有效水分扩散系数,并利用Arrhenius公式求出了10mm^25mm粒径下的干燥活化能.

In order to investigate the influence of flue gas temperature and particle size, an experiment was carried out to obtain the drying features of lignite particles at different initial gas temperature （600 ℃-900 ℃） and particle size （10 mm-25 mm）. It was found that the fallingrate drying period was the main drying period. And the influence of flue gas on the drying was less significant during the high temperature （600 ℃-900 ℃） compared with the low temperature. Specific to the lignite drying process feature of water migration and pore characteristics, this kinetics model that the reducing of water was mainly resulted from evaporation out of coal particles drying was established on the basis of Knudsen diffusion law, and the effective diffusivity coeffi- cient （De） of different flue gas temperature was calculated. At the same time, the activated energy for,the moisture diffusion of different particle size（10 mm-25 mm） were calculated by applying Arrhenius type relationship.