Characteristics of biomass gasification by oxygen-enriched air in small-scale auto-thermal packed-bed gasifier for regional distribution

To utilize the by-product oxygen produced by regional distributed water electrolysis plant for the creation of "hydrogen society" in Japan, a small-scale auto-thermal packed-bed gasifier using oxygen-enriched air was proposed. In this study, the packed-bed height, temperature distribution, syngas concentration, lower heating value (LHV) of syngas, tar content, cold gas efficiency (CGE), and carbon conversion were assessed to verify the feasibility of the scheme. The LHV improved from 3.85 to 4.66 MJ/Nm3, the tar content reduced from 0.81 to 0.17 g/Nm3, and the CGE increased from 81.22 % to 90.69 % as the oxygen concentration increased from 21 % to 25 %. Thermochemical calculations were further performed using FactSage 8.3 to explore the essence of O2-enriched effect. It was found that O2-enriched effect can be ascribed to the synergy of weakened N2 dilution and temperature increasing.