3-3-4 Gasification rate of grass biomass-derived char and the gasification mechanism

Abstract

In this study, we examined the gasification rate of grass biomass with that of woody biomass and clarified the gasification mechanisms. The gasification rate of grass biomass was approximately 10 times that of the woody biomass. The increased surface area of the pores on grass biomass-derived char (specific surface area) was less than 1/3 that of the woody biomass-derived char. The surface area of grass biomass-derived char was saturated near X=0.5. The grass biomass-derived char consisted mainly of leaf sheaths, which are aggregates of vents. Because gasification agents can easily pass through vents, the reaction mechanism in grass biomass-derived char was predicted to be similar to that on its external surface. The tube walls of the vents were as thin as several μm and the carbon structure of the grass biomass was more amorphous, then external surface rapidly eroded (including collapse). As a result, increases in the surface area of the pores on grass biomass-derived char were inhibited and the gasification rate constant K_p was higher than that of woody biomass.