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.