The modified model for pyrolysis of cylindrical wood

摘要

Pyrolysis is known as one of the promising thermochemical conversion techniques in producing solid (charcoal),liquid (tar) and gaseous products.In the present study,deposition coefficient,i.e.the fraction of volatile and gases deposited on the char due to the secondary reaction,is introduced to modify the chemical kinetics model and the heat transfer model.The fourth order Runge-Kutta method is used to solve the kinetic model and the tri-diagonal matrix algorithm is used to solve the heat transfer model for cylindrical wood with the radius in the range 0.003 m ～ 0.011 m and the final pyrolysis temperature in the range 623 K ～ 780 K.The numerical results provide the final pyrolysis time and the effects of secondary reaction.As the wood radius increases,the final pyrolysis time and the effect of secondary reaction increase.Finally,the model developed in the present study is validated by experimental data.It is shown that the simulating results based on the modified model agree well with experimental results and are better than that based on models in literatures which does not consider deposition coefficient.