Direct chemical looping gasification of pine sawdust using Fe₂O₃-rich sludge ash as an oxygen carrier: Thermal conversion characteristics, product distributions, and gasification performances

The thermal characteristics and kinetic parameters of direct chemical looping gasification (DCLG) of pine sawdust (PS) were researched using a TGA at a well-defined heating rate. The three-phase product yields, syngas contents, DCLG performances, and multiple reactions were analyzed by a DCLG evaluation apparatus coupled with a gas chromatography (GC). TGA results indicated that, as the SA blending ratio was at 10%, the interactions between PS and SA mainly occurred at lower temperatures, while with the SA ratio increasing, more interactions also happened at the higher temperatures. The kinetics analysis results indicated that the activation energies of the first thermal decomposition zone of PS were independent with the SA ratios, while the values of the second and third zone were related to them. Through DCLG evaluation experiments, it was found that the SA presence, and the increase in SA ratios would promote the conversion of PS, while decrease the gasification performance. As the gasification temperature increased, the DCLG performance of PS would be improved, but the highest heating value of syngas produced would be obtained at 750 °C. The multiple DCLG experiments showed that the reaction performance of Fe₂O₃-rich sludge ash as an oxygen carrier could almost keep stable. The research results of this paper could give some useful guides for the potential application of Fe₂O₃-rich sludge ash as an oxygen carrier in direct chemical looping gasification of biomass feedstock.