In this paper,a model for fast coal pyrolysis in a cocurrent downer reactor is developed,in which both hydrodynamics and coal pyrolysis kinetics are simultaneously considered.The results of simulations based on this model display reasonable agreement with experimental data obtained using Huolinhe coal as the feedstock,and this model is therefore suitable for predicting the fast pyrolysis of specific coal types.A series of simulations of fast coal pyrolysis in a cocurrent downer demonstrated that coal devolatilization is almost complete in the inlet region within a time span of 0.4 s,and that higher temperatures improve the pyrolysis efficiency.However,the yield of liquid products is decreased with increasing pyrolysis temperatures,especially above 670 ℃,because of additional cracking of the liquids.
