H2 rich gas production via pressurized fluidized bed gasification of sawdust with in situ CO2 capture

• A pressurized fluidized bed reactor was designed and constructed for gasification tests.
• CaO sorption enhanced gasification of sawdust was investigated under pressurized conditions.
• H2 production was promoted with the increase in gasification pressure, CaO/C, H2O/C and T.
• Pressurized operation promoted gasification reactions and enhanced CaO carbonation.
• Pressurized operation increased the carbon conversion and cold gas efficiency of gasification.

The continuous increase in energy demand and the growing attention on global warming worldwide have aroused great research interest in a novel near zero emission energy utilization system which is based on CaO sorption enhanced gasification. This paper presents the experimental results of pressurized CaO sorption enhanced sawdust gasification in a self-design pressurized fluidized bed gasifier, aiming to survey the effects of reaction pressure, CaO to carbon mole ratio (CaO/C), steam to carbon mole ratio (H2O/C) and reaction temperature (T) on hydrogen (H2) production under pressurized gasification conditions. Results showed that the pressurized operation not only promoted gasification reactions, but also apparently enhanced CaO carbonation. Within the experimental ranges investigated in this work, H2 fraction and H2 yield were both elevated with the increase in reaction pressure, CaO/C, H2O/C and T. Comparing with previous atmospheric fluidized bed gasification results, pressurized gasification was capable of producing syngas with higher H2 fraction and lower CO2 fraction even at lower CaO/C, H2O/C and T. It was also verified that pressurized operation increased the carbon conversion and cold gas efficiency for CaO sorption enhanced sawdust gasification.