Calcination apparatus for use in fluidized-bed burning installation for powdery raw material

In a calcination apparatus for use in a fluidized-bed burning installation for powdery materials comprising a fluidized-bed burning furnace, a calcining furnace for calcining the powdery materials and which is fluidically connected to the fluidized-bed burning furnace, the fluidized-bed burning furnace being subject to producing scattered clinker particles which become entrained in exhaust gas flowing from the fluidized-bed burning furnace to the calcining furnace and which can create draft variations in apparatus located upstream of the calcining furnace with respect to the direction of flow of powdery materials flowing to the calcining furnace and to the fluidized-bed burning furnace, the improvement in combination therewith which comprises:

• means for preventing scattered clinker particles from reaching the calcining furnace, said means comprising an upper vortex chamber disposed immediately below said calcining furnace for swirling charging secondary combustion air into said calcining furnace, means for supplying secondary combustion air into said upper vortex chamber, a cyclone type lower vortex chamber disposed immediately below said upper vortex chamber and fluidically communicated therewith, a riser duct fluidically connecting the fluidized-bed burning furnace only to said lower vortex chamber for receiving gas from the fluidized-bed burning furnace and transferring such received fluid directly and only to said lower vortex chamber, said lower vortex chamber being fluidically interposed between said fluidized-bed burning furnace and said upper vortex chamber and preventing the scattered clinker particles produced in the fluidized-bed burning furnace from reaching said upper vortex chamber and the calcining furnace, means for supplying primary air to said fluidized-bed burning furnace, and a chute connecting said lower vortex chamber to said fluidized-bed burning furnace for returning the scattered clinker particles separated and trapped in said lower vortex chamber into the fluidized-bed burning furnace.