Biomass gasification furnace

A biomass gasification furnace that produces a fuel gas by heating and gasifying a ligneous biomass raw material, the biomass gasification furnace comprising:

• an outer tube provided so that an axis thereof extends in a vertical direction;
• an inner tube provided inside the outer tube so that an axis thereof extends in the vertical direction and so that a lower end thereof is located higher than a lower end of the outer tube;
• and
• a reactor that heats the outer tube from outside,
• wherein
• a combustion air supply portion that supplies combustion air is provided inside the inner tube so as to be spaced from the lower end of the inner tube,
• the biomass raw material is supplied from above to the inside of the inner tube so as to form an accumulation portion in which the biomass raw material has accumulated from the lower end of the outer tube to a location higher than the combustion air supply portion inside the inner tube, and the fuel gas is produced in the accumulation portion, and
• the fuel gas that has been produced is discharged through a space between the inner tube and the outer tube.