Patent ID: 7895957

Claim:
A fluidized-bed furnace which incinerates a material to be incinerated while fluidizing a fluidized medium in a furnace casing, the fluidized-bed furnace comprising: a heat exchanger tube which is provided in the furnace casing and whose channel provided in a tube main body is heat-exchanged with an external part of the tube main body, wherein the heat exchanger tube forms a serpentine configuration having at least two straight tube main bodies extending in a longitudinal direction and a curved portion interconnecting respective adjacent ones of the at least two straight tube main bodies, the at least two straight tube main bodies extending parallel to each other and respective juxtaposed ones of the at least two straight tube sections linearly contacting one another at a contact location along the longitudinal direction; a first cover layer covering a tube main body outer side of each one of the tube main bodies to completely cover the contacting, juxtaposed ones of the tube main bodies except at respective contact locations; and a second cover layer covering a first cover outer side of the first cover layer on each one of the tube main bodies to partly cover the first cover layer, the second cover layer being at least arcuately-shaped as viewed in cross-section, covering the whole side portions of the straight-tube portion, and not provided on both sides of a place where the tube main bodies are in contact with each other, and an upper terminal end of a second cover layer on the lower tier is disposed apart from a lower terminal end of a second cover layer on the upper tier, wherein the first cover layer is made of a material higher in ductility than the second cover layer, and wherein the second cover layer is made of a material higher in hardness than the first cover layer.