PURPOSE: To prevent carbide sludge from adhering to the inside wall of vaporization cylinder, by providing a rotary vaporization cylinder to a combustion chamber, and by floating granular material in the cylinder in order to remove carbide from fuel gas.

CONSTITUTION: When propane gas is fed from a propane fuel intake port 18 into a vaporization cylinder 4 which is rotated along with a fuel feed pipe 3, the fuel is burnt in the cylinder which is red-heated. At this time, when kerosene is fed into the cylinder from a fuel pipe 16, it is injected into a combustion chamber 20 through a porous flame plate 14, and combustion is started in the chamber. Feed of propane gas is stopped at this point of time. Since the inside of the cylinder 4 is be short of oxygen, carbide sludge and the like are produced in it and they adhere to the inside wall of the vaporization cylinder 4. To cope with this condition, some granular material (iron balls) 5 is put into the vaporization cylinder 4, by which the adhered carbide is reduced into powder by the movement of iron balls 5, which occurs in acompany with the rotation of the vaporization cylinder 4. The sludge is fallen off and is flown down into a combustion tube 2, flowing into a combustion chamber 20 along with vaporized fuel, and is burnt there.