Abstract: The fluid bed apparatus has a chamber (1) including a plenum (11) and a perforated base plate (3) is located above the plenum (11). An inlet (2) and an outlet (7) are provided for process gas. A discharge opening (8) has a lower edge (8a) and an upper edge (8b) and defining a height and an opening area, the base plate (3) being positioned above the lower edge (8a) of the discharge opening (8) such that the opening area of the discharge opening (8) is divided into an opening area (Aa) below the base plate (3) and an opening area (Ap) above the base plate (3).

Abstract: The wet cleaning of filter cartridges (4) in fluidised-bed apparatuses and similar process units, without their being dismantled, is carried out by means of cleaning fluid sprayed out of nozzle orifices (10) arranged in the form of a ring, the nozzle orifices (10) being installed in the filtered exhaust-gas space (7) and the filter cartridge (4) being moved through this ring of nozzle orifices (10) by a lifting device (17). In a preceding flushing cycle, the filter cartridge (4) is filled with cleaning fluid and is then subjected to an ultrasonic transmitter (26) and with pressure pulses. The nozzle orifices (10) are designed and arranged in such a way that the issuing cleaning jets strike the filter casing (5) tangentially at an angle of inclination .alpha. and thus set the filter cartridge (4) in rotation. The best possible cleaning effect is achieved by the rotation and lift of the filter cartridge (4).