Abstract: An apparatus for carrying out a physical and/or a chemical process, such as a heat exchanger, a reservoir, in which a fluidized bed of granular material is present, is provided with upwardly directed tubes to a top box. Particles circulate up through the tubes, to a downcomer arranged outside the reservoir. The top of the downcomer is connected to a separating device, and the bottom of the downcomer opens into a collecting reservoir. The collecting reservoir communicates via a valve with the fluidized bed in the reservoir.

Abstract: An apparatus for carrying out a physical and/or chemical process, such as a heat exchanger, comprising a reservoir (1) provided with upwardly-directed tubes (2), in which reservoir (1) a fluidized bed is present consisting of granular material and maintained by medium to be treated. The invention is provided with means for causing fluidized bed particles to circulate from a bottom box (3) of the reservoir (1) through the riser pipes (2), a top box (4) and a downcomer (15) back again to the bottom box (4), and with a closable bypass line (27) for feeding a portion of the fed medium to the riser pipes (2) while shortcutting the fluidized bed.