褐煤等温干燥过程及动力学研究

为研究褐煤干燥过程,利用煤质水分分析仪和微分热重分析方法,对不同粒级的褐煤在不同干燥温度下进行等温干燥试验,得到了样品含水率与干燥时间、干燥速率与含水率的关系曲线。通过粒级分布系数对褐煤进行含水率折算,并用不同干燥模型对试验数据进行拟合,得到了在介质温度140℃下3个干燥阶段的干燥方程及干燥动力学参数。结果表明,引入粒级分布系数得到的干燥速率特征常数k值,与不同粒级的干燥速率特征常数k的均值相近。根据褐煤的干燥速率和水分的存在形式,将褐煤干燥过程分为3个干燥阶段,分析得出干燥方程模型分别用线性干燥模型、Wang经验模型、Page模型较为合理。根据Arrhenius经验公式建立了ln k与1/T的关系,得到褐煤干燥的界面蒸发活化能Ea=17.088 k J/mol,指前因子A=12.47 min~(-1)。

Study on isothermal drying process and kinetics of lignite

For the research of lignite drying process,using the water quality analyzer and differential thermogravimetric analysis method,isothermal drying experiments were carried out on lignite with different grain sizes at different drying temperatures.The curves of moisture content and drying time and the curve of drying rate and water content were obtained.The moisture content conversion of lignite with different particle sizes was made by the size distribution coefficient,and the experimental data were fitted with different drying models.The drying equation and the kinetic parameters of the three drying stages were obtained at the medium temperature of 140 ℃.The results showed that the drying rate characteristics constant k,which was obtained by introducing the particle size distribution coefficient,was similar to that of the drying rate characteristic constant k with different particle sizes.According to the drying rate and moisture content of lignite,the drying process was divided into three stages.The drying equation model was obtained by using linear drying model,Wang empirical model and Page model respectively.According to the empirical formula of Arrhenius,the relationship between Ink and 1/T was established,and the activation energy of Ea was 17.088 kJ/mol and the pre exponential factor A was 12.47 min-1.