(125f) Numerical Study On Coal/Biomass Gasification in the Downer of a Triple-Bed Combined Circulating Fluidized Bed

Gasification can convert the carbonaceous feed stocks into synthetic gases, which can be used in the chemical processes or electricity generation in the downstream processing. Through gasification, the energy can be used more effectively, and the emission of CO₂ can also be reduced greatly. In this study, the gasification of both coal and biomass was studied by numerical simulation. The coal gasification through partial oxidation and stream gasification was simulated in the downer of a triple-bed combined circulating fluidized bed. It was found that the steam gasification could produce more synthetic gases than partial oxidation gasification.  With decreasing particle size, increasing wall temperature or inlet gas temperature, the conversion ratio of volatiles and char could be enhanced.  Biomass gasification in the bubbling fluidized bed was simulated numerically, and the gasification agent was the mixture of CO₂ and air, thus the renewable biomass could not only provide the clean energy, but also help capture CO₂.  CO₂ percentage in the gasifying mixture, CO₂-to-biomass ratio, moisture content and size of wood chips on the gasification performance were investigated in this study.