HEAT EXCHANGER AND METHOD OF OPERATION

PROBLEM TO BE SOLVED: To obtain clean high temperature gas without containing dust by heat recovering from high temperature exhaust gas containing the dust. SOLUTION: A first fluidized bed heat exchanger 45 constituting fluidized beds 44a and 44b, a second fluidized bed heat exchanger 49 constituting fluidized beds 48a and 48b, high temperature exhaust gas containing the dust is fed to the first fluidized bed heat exchanger 45, the clean gas without containing dust as the air is fed to the second fluidized bed heat exchanger 49. Heating medium is supplied through a fourth air tight exhaust means 51 from the fluidized bed 48b that is at the under step of the second fluidized bed heat exchanger 49 to the fluidized bed 44a that is at the upper step of the first fluidized bed heat exchanger 45 by a transferring means 87. Heating medium forming the fluidized bed 44b that is at the under step of the first fluidized bed heat exchanger 45 is conducted to the fluidized bed 48a that is at the upper step of the second fluidized bed heat exchanger 49 by chutes 83 and 84 being intervened with a third air tight exhausting means 50. The clean gas without containing the dust is heated by the exhaust gas containing the dust through indirect heat exchange circulating heating medium.