Gasification of miscanthus x giganteus in an air-blown bubbling fluidized bed: A preliminary study of performance and agglomeration

Gasification of Miscanthus x giganteus (MxG) was conducted in an air-blown bubbling fluidized bed (BFB) gasifier using magnesite as bed material and a moderate rate of biomass throughput (246.82-155.77 kg/m²h). The effect of equivalence ratio (ER) (0.234-0.372) and bed temperature (645-726 C) on the performance of gasification was investigated. The results reveal that MxG is a promising candidate for energy production via BFB gasification; of the conditions tested, the optimal ER and temperature are approximately 0.262 and 645 C, where no sign of agglomeration was found. The product gas from this condition has a higher heating value of 6.27 MJ/m³, a gas yield of 1.65 N m³/kg_biomass (39.5% of CO and 18.25% of H ₂ on N₂ free basis), a carbon conversion efficiency of 94.81% and a hot gasification efficiency of 78.76%. Agglomeration was observed at some higher temperature conditions and believed to be initiated by the formation of fuel-ash derived low melting temperature K-rich (potassium) silicates (amorphous material that cannot be detected by XRD). It is suggested that relatively low temperature (650 C) needs to be used for the gasification of MxG to avoid potential agglomeration.