NOVELTY - A biomass gasification spiral combustion boiler with composite hearth and fixed grate comprises primary air chamber (1), boiler door (3), boiler cylinder (6), and a base (16); where the base is equipped with biomass fuel gasification hearth (15) and spiral combustion hearth (8) separated by a separating wall (9); and the middle of the separating wall is equipped with biomass fuel gas outlet (4) and spiral combustion hearth secondary air nozzle group (11) spraying towards the spiral combustion hearth that are connected with the biomass fuel gasification hearth and the spiral combustion hearth.    USE - The biomass gasification spiral combustion boiler with composite hearth and fixed grate is useful for industrial applications.    ADVANTAGE - The biomass fuel gas generated by the biomass gasification spiral combustion boiler with composite hearth and fixed grate will rotate strongly and combust in the spiral combustion hearth; where the solid particles in smoke gas can be deposited and separated in the combustion ash chamber. Moreover, the boiler has high heat efficiency and completely eliminates black or yellow smoke phenomenon of conventional boiler combusting biomass fuel. Additionally, the smoke gas exhausted by the boiler is colorless and transparent.    DETAILED DESCRIPTION - A biomass gasification spiral combustion boiler with composite hearth and fixed grate comprises primary air chamber (1), boiler door (3), boiler cylinder (6), and a base (16); where the base is equipped with biomass fuel gasification hearth (15) and spiral combustion hearth (8) separated by a separating wall (9); the middle of the separating wall is equipped with biomass fuel gas outlet (4) and spiral combustion hearth secondary air nozzle group (11) spraying towards the spiral combustion hearth that are connected with the biomass fuel gasification hearth and the spiral combustion hearth; the upper part of the separating wall is arranged with heat storage tracery wall (12); the lower part of the biomass fuel gasification hearth is equipped with fixed grate (2); the primary air chamber is equipped below the fixed grate; the right side wall of the biomass fuel gasification hearth is equipped with secondary air nozzle group (14) of the biomass fuel gasification hearth; the left side wall of the spiral combustion hearth is equipped with spiral boiler arch (10); the spiral boiler arch is used together with the biomass fuel gas outlet and the secondary air nozzle group of the biomass fuel gasification hearth; the fire-resistant bottom liner is equipped on lower part of the spiral combustion hearth; the combustion ash chamber (5) is equipped behind the biomass fuel gasification hearth and the spiral combustion hearth; and the smoke outlet (13) connects the spiral combustion hearth and the heat storage tracery wall with the combustion ash chamber.    DESCRIPTION OF DRAWING(S) - The drawing shows a schematic diagram of the biomass gasification spiral combustion boiler with composite hearth and fixed grate.    Primary air chamber (1)    Fixed grate (2)    Boiler door (3)    Biomass fuel gas outlet (4)    Combustion ash chamber (5)    Boiler cylinder (6)    Spiral combustion hearth (8)    Separating wall (9)    Spiral boiler arch (10)    Spiral combustion hearth secondary air nozzle group (11)    Smoke outlet (13)    Secondary air nozzle group (14)    Biomass fuel gasification hearth (15)    Base (16)