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 CO ₂ 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 CO ₂ 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 R _i. With the reaction rate R _i,s at steady-state under different temperatures, the intrinsic reaction rate of char CO ₂ gasification was expressed as R _i=1.243×10 ³exp(-19243.5/T) g/(m ²(min).