过热蒸汽干燥凝结段的干燥动力学特性

为了深入了解过热蒸汽干燥过程的机理,进而优化干燥操作,开展了褐煤热空气干燥和过热蒸汽干燥对比试验,结果表明:在过热蒸汽干燥的初始阶段存在明显的蒸汽凝结现象,其干燥动力学特性与热空气干燥存在明显不同。通过对过热蒸汽干燥动力学过程的理论分析,研究了过热蒸汽凝结对干燥过程初始阶段的影响。在热空气干燥过程数学模型的基础上,结合过热蒸汽的凝结现象,对过热蒸汽干燥的数学模型进行了改进。经试验结果验证,改进的数学模型具有很好的拟合精度,决定系数大于0.97。研究为优化干燥设备设计和操作条件提供了依据。

Drying kinetics of condensation stage in super-heated steam drying

In order to explore the mechanism of the drying process and to optimize the drying operation, the comparative test was conducted with hot air drying and super-heated steam drying for lignite. The results showed that the steam condensation happened obviously in the initial stage of the super-heated steam drying, which resulting the obvious different drying kinetics compared to the hot air drying. The effect of the steam condensation on the initial stage of the drying process was studied through theoretical analysis of drying kinetics of super-heated steam drying. The mathematical model of super-heated steam drying was improved by combining the steam condensation on the basis of the mathematical model of the hot air drying. The experimental results verified that the fitting precision of the improved mathematical model was well and the determination coefficient was above 0.97. The study can provide a basis for optimizing the design and operating conditions of the drying equipment.