PURPOSE: To eliminate a special driving force for a rotary shaft, provide an energy saving and a convinient transportation of the unit by a method wherein the rotary shaft for the combustion fan is connected to a crank mechanism for a hot gas reciprocating engine driven by the combustion at an auxiliary combustion part and then rotated by the crank mechanism.

CONSTITUTION: When the valve of an oil volume adjusting unit 25 is opened, the oil is flowed from an auxiliary oil tank 24 to the bottom part of the inner cylinder 1a of a preliminary heating cylinder 1. Upon ignition of the oil, the preliminary combustion is performed. As a result, the heating part part 27a in a hot gas reciprocating enging 27 faced in the inner cylinder 1a is heated, the air contained in the cylinder 28 performs a work due to the difference in temperatures between the heating part 27a and the cooling part 27b. Then, a displacer 29 and a piston 30 are reciprocated in the cylinder 28, their output is taken out through a crank mechanism 34 to cause a crank shaft 36 to be rotated, resulting in that the rotary shaft 5 for a combustion fan 21 is rotated through a belt 39. Then, a pump 41 is driven to cause the oil in an oil tank 12 to be injected from a nozzle 51 and atomized into a gasification cylinder 4 through 4 defuser 6.