Biomass air-water vapour gasifier

The invention discloses a biomass air-water vapour gasifier. A biomass fuel performs pyrolysis-combustion and generates reactants in a combustor, which communicates with at least one steam pipeline. High-temperature steam is transferred into the combustor through the steam pipeline and performs a gasification reaction with the reactants. Due to the arrangement of the steam pipeline, the introduced steam is used as a gasification agent to participate in the gasification reaction so as to obtain medium heating value biomass gas by pyrolysis-combustion and gasification of the biomass fuel. The heating value is raised by 30-40% and the gas output rate is enhanced by 20%.