PURPOSE: To gasify powder fuel in burning it so as to improve the combustion efficiency by a method wherein a screw conveyor for carrying powder fuel is provided inside a combustion furnace and to a burner nozzle which extends from the forward end of the outer cylinder of the screw conveyor and looks out through the exhaust gas hole of the combustion furnace a stream of air for combustion is sent through the shaft, which is hollow, of the screw conveyor.

CONSTITUTION: A screw conveyor 9 for conveyance is held horizontally inside a combustion furnace 1. From the forward end of the outer cylinder 11 of this conveyor 9 a burner nozzle 17 extends in such a manner as to look out through the exhaust gas hole 7 of the combustion furnace 1. The shaft 13a of the screw conveyor 9 is hollow along the axis and its rear end is connected to a blower through a swivel joint 19. Holes 23 are opened through the burner nozzle 17 circumferentially. In the upper part of the combustion furnace 1 a screw conveyor 25 for feeling powder fuel is provided as a means of feeding powder fuel to the combustion furnace 1 and the screw conveyor 9 for conveyance. As a result, powder fuel can be gasified for the combustion and an improvement in combustion efficiency can be achieved.