GB1474422A - Process and apparatus for the treatment production and separation of products in granular form - Google Patents

Abstract

1474422 Fluidised bed contacting and separating; coating granular material CHARBONNAGES DE FRANCE 26 July 1974 [27 July 1973 24 June 1974] 33163/74 Headings B1F, B2H and B2L [Also in Division F4] An apparatus for treating products in granular form in a fluidised bed of pulverluent material and for subsequently separating the products from the pulverluent material comprises a container 10, Fig. 1, a bed of pulverulent solid material provided within the container, means 2 for introducing a fluidisation agent, e.g. gas, into the container, the container including a distributor 2' for feeding the fluidising agent to only a vertical portion of the bed so as to divide the bed into fluidised and non-fluidised zones, means 3 for vibrating the container and the fluidised bed, means 7 for screening the treated granular products from the pulverulent material and for discharging them through vibration outside the container. The bed of pulverulent material is retained on a grid 4. The distributor 2' is bounded by an annular deflector 9 which prevents fluidisation of the peripheral portion of the bed. Alternatively, the grid 4 has an unperforated annular zone, as shown also at 5 in Fig. 5. In operation, circulating currents 6 are established in the bed and the vibrations which are applied in the direction of the arrows f by a vibrator 3 causes the treated granular product retained by the screen 7 to move up the surface of the latter and overflow at 8. In a modification, Figs. 3 and 4 (not shown), a screen and a deflector or an unperforated portion of the grid are provided at each lateral longitudinal side of a rectangular container. In Fig. 5, the screening means consists of an edged helicoidal perforated ramp 11 provided on the inner wall of a cylindrical container 10. A helicoidal deflector 12 is disposed below the ramp to return to the bed the pulverulent solid material passing through the perforations of the ramp. Vibrations are provided by two unbalanced motors 3. In a modification of Fig. 5, Figs. 7 and 8 (not shown) the central, instead of the annular, portion of the grid 4 is impermeable to fluidising gas. In all the embodiments heating of the fluidised bed may be effected by heating the current of fluidising gas or by withdrawing a fraction of the pulverulent solid material, heating it and recycling it. The bed of pulverulent solid material may be composed either of the product treated or of an auxiliary solid material. The apparatus may be used for chemically treating or coating granular products in a fluidised bed.