GB1200996A - Improvements in or relating to air separators for powders and granular materials - Google Patents

Abstract

1,200,996. Centrifugal separators; pneumatic classification. BRITISH "REMA" MFG. CO. Ltd. 19 May, 1969 [24 May, 1968], No. 24817/ 68. Headings B2H and B2P. A pneumatic separator for classifying particulate material comprises a pipe 7 for feeding the material to be classified to the interior of an angularly vaned rotor 12, a spinner disc 13 for flinging the material to the rotor vanes, an inner cyclone casing B with its top 4 surrounding the rotor 12, a fan 14 for producing a swirling stream of gas in the space between the casing B and the outside of the rotor 12, a passage leading from the interior of the rotor to the inlet of a circulating fan 11, an outer cyclone casing A with its top 1 surrounding the circulating fan 11, an axial pipe 16 connecting the lower part 3 of the outer casing A to the inlet of the swirling fan 14, an outlet 20 in the bottom of the inner casing B for removal of coarse particles, an outlet 19 in the bottom of the outer casing A for removal of fine particles, and a tube connected to the fan 11 and mounted in a bearing 8 and driven by a motor 10 so as to rotate the fans 11, 14, the rotor 12 and the spinner disc 13. In operation, the material is flung from between the disc 13 and an upper annular plate 15 into the swirling stream of air and is entrained thereby through the vanes of the rotor 12 in which the action of centrifugal force on the coarse particles is greater than that of the drag force of the inwardly moving gas stream so that these particles are flung outwardly in the gas stream and are separated therefrom in the inner cyclone casing, whereas the fine particles on which the action of the drag force is greater, are entrained with the gas stream into the fan 11 and flung thereby into the outer cyclone casing where they become separated from the gas stream which is recirculated via the pipe 16. A valve 17 in the pipe 16 controls the rate of circulation of the gas stream. A labyrinth seal is provided at 18. The rotor vanes are non-radial. The outlets 19, 20 are closed by receptacles or air locks so that the entire gas content is retained within the separator. In a modification, Fig. 3, vents 23 controlled by an adjustable shutter 24 are provided in the wall of the inner cyclone casing B for tapping gas from the descending gas stream in the outer casing and directing it into the inner cyclone casing so that it flows upwardly through the space between a flared end portion 21 of the pipe 16 and a conical deflector 22 and thereby removes from the descending flow of coarse particles any agglomerated fine particles entrained therein and/or any ultra-fine particles which remain in suspension in the recirculated air and direct them towards the rotor 12. Auxiliary blades 25 are provided on the upper shroud of the fan 11 to produce suction conditions so as to prevent emission of dust to the atmosphere via the gap between the tube 9 and the cover plate 2 of the outer cyclone casing.