Numerical Simulation and Experimental Research on Drying Behavior of a Single Lignite Particle (SLP) under High-Temperature Flue Gas

Abstract

The drying behavior of a single lignite particle (SLP) in high-temperature (600–900 °C) flue gas was investigated by experiment and numerical calculations. A self-designed horizontal fixed-bed reactor was employed for high-temperature drying experiments. Based on the drying curves obtained from these experiments, no constant-drying-rate stage was found, and the SLP drying process included stages with increasing and decreasing drying rates. To explore the drying process in depth, a mathematical model was developed in which the SLP was simplified into a simple spherical model. Based on the dry–wet zone theory, the heat- and mass-transfer equations were established to describe the drying process. The simulated results calculated using MATLAB agreed well with the experimental data. The model can predict SLP drying behaviors including the effects of the drying time, the surface and internal temperature distributions of the lignite particle, the migration of the evaporation interface inside the particle, and so...