PURPOSE: To make it possible to regenerate the fluidized medium effectively by use of a device of simple structure by a method wherein the fluidized medium is extracted from a fluidized bed furnace for burning ashes of heavy crude oil, the extracted fluidized medium adhered with the ashes is mixed with water and another ashes of the heavy crude oil and the mixture is returned to the furnace.

CONSTITUTION: EP ashes generating in a power plant using the heavy crude oil as a fuel are supplied to the fluidized bed furnace 11 to be burned in a fluidized bed consisting of fluidized sand. In this case, as the fluidized sand is adhered with the ash component of the EP ashes, it is extracted by a sand extracting pipe 12 provided at the fluidized bed of the furnace 11 and is supplied to a mixer 13. Further, another EP ashes and water are supplied to the mixer 13 through pipes 14 and 15, respectively, and after they are mixed sufficiently, the mixture is supplied into the furnace 11 by means of conveyers 16 and 17. Consequently, the furnace 11 can be operated safely by use of the above mentioned simple device and it becomes possible to regenerate effectively the fluidized sand as the fluidized medium without crushing the same.