PURPOSE: To burn various fuel without smoke in a natural state without burner or stack, to output 100% of thermal efficiency, to be utilized for all heat sources and to solve problems of atmospheric contamination, energy.

CONSTITUTION: An ignition thorium emanation is placed on a furnace on a fire grate of a combustion furnace, the emanation is first primarily once red- heated by carbonization, etc., arbitrary solid fuel is then secondarily cast in the furnace to start combustion, an oxidation reaction is tertiarily conducted on the grate to discharge oxidized heat toward a lower grate. Further, exhaust gas containing only pure carbon dioxide, carbon dioxide gas including no black smoke, PM, particle substance at all is quadratically discharged, and drying, boiling, burning, heating, warm water, steam are quinarily output mainly by dissipating heat by converting the clean heat or to infrared ray.