EXPERIMENTAL AND MODELING INVESTIGATION OF LIGNITE DRYING IN A FLUIDIZED BED DRYER

摘要

The nitrogen as drying medium and the fluidized bed were used to study the drying characteristics of two kinds of lignite. The results show that the drying process of the lignite could be divided into three stages: a pre-heating period, a constant heating period, and a quick-down heating period. For the same lignite sample, the drying rate of lignite samples increases with rising drying temperature or flow rate of drying medium. For the different lignite samples, the composition structure of lignite and the modes of occurrence of moisture in the lignite influence the drying characteristics of lignite, besides drying medium temperature and flow rate influence lignite drying. According to the heat transfer rule equation of wet-ball in the forced flow, the drying rate formula of lignite particle in the fluidized bed has been got based on the heat transfer theory and mass transfer theory, and the formula can well interpret the effect of the experimental parameters on the lignite drying.