Thermal behavior and kinetics of the pyrolysis of hyper coal

For the effective and clean use of low rank coal,hyper coal was obtained by organic thermal dissolved process. The pyrolysis process of raw coal and hyper coal was studied by thermogravimetric analysis methods.The characteristic parameters were used to characterize the process of pyrolysis of coal samples.The kinetics of different stages was determined by piecewise model fitting method and its corresponding pyrolysis kinetic parameters.The results show that there is a thermal hysteresis in the process of pyrolysis of raw coal and hyper coal with the increasing of heating rate,which has great influence on the medium temperature stages of raw coal and low temperature stage of hyper coal pyrolysis,respectively.By subsection analysis,the one-way transport diffusion model is adapt to lower and medium temperature range,and second order chemical reaction is adapt to higher temperature range of raw coal. The three stages of hyper coal pyrolysis process can be well described by one-way transport diffusion model,three-way transport diffusion model and second order chemical reaction,respectively.