粉煤气化条件下不同粒径半焦的表征与气化动力学

利用可模拟真实粉煤气化条件的平流火焰反应器制取了同一煤种的2种不同平均粒径的半焦，并对其进行了物理表征和气化反应动力学研究. 其物理表征显示，小颗粒半焦的平均比表面积远小于大颗粒半焦. 半焦的CO2气化实验表明，含很多小孔的大颗粒半焦的气化反应受内扩散影响显著，比表面积较小的小颗粒半焦具有更高的气化反应速率. 利用随机孔模型导出了反应速率Ri. 根据小颗粒半焦在不同温度下平衡态时的反应速率Ri,s值获得半焦气化的本征气化反应速率表达式为Ri=1.243′103exp(-19243.5/T) g/(m2×min).

Characterization and Gasification Kinetics of Char with Different Particle Sizes under Gasification Conditions of Pulverized Coal

Char samples with different averaged diameter particles were prepared from a given raw coal in a flat flame reactor which simulated the real gasification conditions of pulverized coal.Their physical structure was characterized and their CO2 gasification kinetics studied.The averaged specific surface area of small particle char was far lower than that of large one.Analyzing the experimental data of char CO2 gasification found that although the specific surface area of small char was lower than that of the large char,the small char had higher gasification reaction rate.This is because the large particle char contained lots of meso-pores and caused the inner diffusion limit to the gasification reaction.The random pore model was used to derive a gasification rate Ri.With the reaction rate Ri,s at steady-state under different temperatures,the intrinsic reaction rate of char CO2 gasification was expressed as Ri-1.243-103exp(-19243.5/T) g/(m2-min).