Lignite drying is very important for improvement of lignite quality. In order to simulate evaporation process of water in lignite particle during drying in high temperature flue gas

a mathematical model was established for the unsteady drying process of single lignite particle at high and variable temperature using finite volume method

and the fundamental assumption made was that the lignite particle was spherical and could be divided into two parts in one-dimensional spherical coordinate system by water evaporation interface that migrates inwards during drying. The model was used to analyze the drying behavior of lignite particle with time and the effect of initial temperature of flue gas and particle size. The variation trend obtained by numerical simulation was similar to that did by experiments for drying process. It was found that the higher initial flue gas temperature and the smaller particle size lead to the faster migration velocity of the water evaporation interface

the lower moisture content of lignite particle and the shorter drying time. There is a linear relationship between the interface migration velocity and the initial flue gas temperature and lignite particle size.