A device for discharging, through a central rotating chimney, fluids from a fluidized bed driven in a rotational movement in the same direction by the rotation of the outer circular wall of a reaction chamber and/or by injection of part of these fluids along the circular wall of a fixed or rotating chamber, and methods for catalytic polymerization, drying, or other treatments of solid particles in suspension in a rotating fluidized bed or for cracking or other catalytic conversions of fluids using this device.