In coal gasification, it has been reported that interaction between the volatiles and char inhibits steam gasification of char. Similarly, it is possible that the inhibition occurs in biomass gasification. For proper design and operation of biomass gasification process, it is necessary to clarify the influence of the volatile-char interaction. However, so far there is few research that quantitatively investigates the interaction in biomass gasification.
In this research, we have developed a two-stage reactor which consists of a drop tube reactor and a thermobalance fixed-bed reactor to investigate the influence of the volatiles-char interaction on gasification rate of char derived from biomass. Initially, in the lower thermobalance fixed-bed reactor char produced by pyrolysis in advance was put into a ceramic basket. Then, after the reactor was heated and biomass sample was dropped into the upper drop tube reactor, pyrolysis started to produce char which was trapped by a filter at the middle of two reactors. Subsequently, the volatiles produced in the upper reactor was fed to the lower thermobalance fixed-bed reactor and contacted with char stocked in advance. After that, char was gasified by feeding steam and the gasification rate of char was measured. We also measured the evolution rates of gaseous products from the lower reactor using a mass spectrometer and a micro chromatograph to examine whether the decomposition of tar is facilitated at the surfaces of char.