PURPOSE: To enable to burn solid fuel with no generation of clinker by installing an opening and closing device for a fuel supply hole, and primary and secondary blast pipes which are placed in nearly tangential direction to an inner diameter of the inside of a burning cylinder and also in two stages at the up and down sides of the cylinder.

CONSTITUTION: As unburnt particles having rather heavy weight are circulating near the wall of a burning cylinder 10, the particles drop downward after collision to a cover 20 and so only small particles are exhausted from a exhaust cylinder 22 after being burnt completely. Burnt ashes generated by burning of solid fuel are enabled to float by primary blast pipes 18a, 18b and secondary blast pipes 19a, 19b and part of ashes are exhausted from a exhaust cylinder 22. As the ashes do not accumulate in a high temp. lower part of the burning cylinder 10, the generation of clinker is prevented. As an opening and closing device 17 is closed at the same time of stopping a screw 16, heat is not conducted to a inner part of a transport pipe 14.