A coupled thermal decomposition model for coal particle pyrolysis

摘要

Based on the porous structure of coal, a coupled thermal decomposition model is developed to describe the coal pyrolysis process more fully and truly. It not only incorporates specific surface change in reaction rate during conversion, but also couples chemical reaction rate happened on pore surfaces with internal diffusion rate of the gaseous product. To validate the applicability of the model, three kinds of coal pyrolysis experiments were carried out. The results show that the model is suitable for all the three stages of coal pyrolysis, which realizes the unification of mechanisms in low-, middle-and high-temperature stages. One set of activation energy and pre-exponential factor is calculated for each stage of coal pyrolysis according to the slope and intercept of the corresponding fitting line. With these kinetic parameters, the numerical solution of this model is obtained. Compared the numerical solution with experimental values, the good agreement between them is observed, which validates the reliability of the model.