Experimental investigation of biomass devolatilization in steam gasification in a dual fluidised bed gasifier

Abstract

In this study, biomass devolatilization, which is the initial stage of steam gasification, was experimentally investigated in a 100kW dual fluidised bed gasifier. In the experiments, pellets of radiata pine sawdust were used as the feedstock, and silica sand was used as the bed material. The operating temperature in the gasifier was varied from 700 to 800°C and N2 was used as the fluidisation agent. Once the devolitilization test was completed, corresponding gasification experiment was conducted at the same operation condition but N2 was switched to steam as gasification and fluidisation agent.From the experimental results, it is found that, in the devolatilization stage, gas yield was increased, and tar yield and concentration were decreased with increase in operation temperature. In this study, significant correlation was observed for gas yield and gas composition between the devolatilization stage and the gasification stage. Correlations on tar concentrations and yield were also clear for gases produced from the devolatilization and gases from the subsequent gasification. This study provides fundamental information for understanding and optimization of the biomass steam gasification.