HEAT RECOVERY SYSTEM

PROBLEM TO BE SOLVED: To obtain a high thermal efficiency while maintaining a favorable combustion state and achieve the miniaturization of a heat exchanger and the reduction of an equipment cost. SOLUTION: A heat recovery system is so constituted as to comprise a combustion furnace 1 for burning a solid fuel or waste, a heat transfer medium for recovering the heat of combustion from the combustion furnace 1, a heat transfer medium tank 2 for storing the heat transfer medium, and a heat exchanger 6 for transmitting heat recovered by the heat transfer medium to other mediums. In this case, the heat transfer medium is composed of a heat transfer oil. Construction is so made that an exhaust gas duct extending from the combustion furnace 1 is connected to the heat transfer medium tank 2 and that heat transfer of the heat of the exhaust gas is performed to the heat transfer oil in the heat transfer medium tank 2. Further, construction is so made that the heat transfer oil is allowed to circulate through a cooling wall 1b constructed in the combustion furnace 1.