Gasification of Miscanthus x giganteus in an Air-Blown Bubbling Fluidized Bed: A Preliminary Study of Performance and Agglomeration

Gasification of Miscanthas 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/m(2)h). The effect of equivalence ratio (ER) (0.234-0.372) and bed temperature (645-726 degrees 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 degrees C, where no sign of agglomeration was found. The product gas from this condition has a higher heating value of 6.27 MJ/m(3), a gas yield of 1.65 N m(3)/kg(biomass) (39.5% of CO and 18.25% of H-2 on N-2 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 degrees C) needs to be used for the gasification of MxG to avoid potential agglomeration.