Circulating fluidized bed boiler

The utility model discloses a circulating fluidized bed boiler, which comprises a hearth, a hearth outlet formed on the upper part of the hearth, a membrane water-cooled wall arranged in the hearth and a tail flue connected with the hearth outlet, wherein a high temperature over-heater is arranged in the hearth; the high temperature over-heater is arranged and fixed above the hearth, and extends into the hearth, and the extended height exceeds the height of the hearth outlet. The circulating fluidized bed boiler can be used for effectively solving the technical problems that the manufacture and installation costs of the boiler are greatly improved, repeated low-temperature combustion and desulfuration reaction cannot be effectively promoted at the same time, the emission of NOx cannot be effectively reduced and the like; and meanwhile, the circulating fluidized bed boiler has the characteristics of low manufacturing cost, high vulcanization efficiency, long service life and the like.