木質バイオマス熱分解過程の反応速度解析と簡易炭化炉における炭化条件の検討

抄録

This paper describes a kinetic analysis of devolatilization rates of woody biomass by a model based upon distributed activation energy model and calculation results of proceeding of devolatilization of woody biomass in a simple carbonizer. Weight loss during pyrolysis of the woody biomass was measured by a TG in three different heating rates. The data of weight loss with time were processed according to the method proposed by Miura to determine provability density functions of activation energy distribution, f(E), and corresponding frequency factors k₀. Original method proposed by Miura cannot be adapted directly for the analysis of devolatilization of biomass because of decreasing in the activation energy with proceeding of the devolatilization. However, approximate activation energy distribution functions and frequency factors, with which devolatilization reaction could be well simulated, were obtained for woody biomass by a modification of original method proposed by Miura. For woody biomass, the provability density functions for the activation energy distribution were so different from those of coals that f(E) could not be expressed by a simple distribution function such as Gaussian distribution. This may correspond to the pyrolysis behaviors of the major components of biomass such as cellulose, hemi-cellulose and lignin. Predicted and measured amounts of remaining volatile matters in the chars were in good agreement. Thus, an optimum operation condition of a simple carbonizer was determined by a model using the parameters obtained. Calculations show a combination of highest heating temperature of 700K, rapid heating, short holding time, and rapid cooling is the best operating condition for a simple carbonizer in the view point of operability and energy saving.