油页岩过热蒸汽的干燥动力学

以油页岩颗粒作为干燥物料,以过热蒸汽和热空气分别作为干燥介质,进行了油页岩干燥实验的研究。当颗粒粒径减小时,油页岩干燥速率越大;过热蒸汽和热空气温度增大时,干燥速率也越大。对比相同条件下过热蒸汽和热空气干燥油页岩的平均干燥速率,发现当干燥介质温度超过逆转点温度时,过热蒸汽条件下的平均干燥速率大于热空气下的数值。实验得出粒径分别为9,7,5 mm的油页岩颗粒逆转点温度值分别是154,179,177℃;逆转点温度值是个变量,随颗粒粒径大小变化而变化。颗粒粒径越大时逆转点温度值越小,粒径较小时逆转点变化不大。采用薄层干燥模型对油页岩的干燥数据进行动力学模拟,可得修正Page模型(Ⅱ)干基水分比w模拟值与实验值的最大绝对偏差是12%,综合比较发现修正Page模型(Ⅱ)能较好地描述油页岩在过热蒸汽条件下的干燥过程。

Drying kinetics of oil shale with superheated steam

The drying process of oil shale particles in superheated steam and hot air was investigated respectively.The experimental results show that the smaller the particle diameter of oil shale or the higher the drying temperature of superheated steam or hot air,the higher the drying rate.Under the same conditions,the average drying rate in superheated steam is higher than that in hot air when the temperature exceeds the inversion point.The inversion temperature of 9,7,5 mm oil shale particle is respectively 154,179,177 ℃.The inversion temperature is a variable,and it decreases with the increase of the particle diameter of oil shale,but it changes little with smaller particle diameter.The drying kinetic data were simulated by the thin-layer drying model.The modified Page model(Ⅱ) can better describe the drying process of oil shale in superheated steam,and the maximum absolute deviation is 12% between the simulated data and the experimental data of dry basis moisture rate w.