Patent GB-1340871-A (GB)
Title: Centrifuges
IPC: B04B5/04
Filed: 1971-04-19
Abstract: 1340871 Centrifugal separators MSE HOLDINGS Ltd 19 April 1971 [10 March 1970] 11491/70 Heading B2P In a centrifuge, a fluid feed and discharge head 3, for supplying fluid to and for removing fluid from, the centrifuge rotor 2, comprises two relatively rotatable and sealable portions, one portion 18, 22, 29 being stationary and the other portion 37, 38 being rotatable with the rotor, and the rotatable portion carrying two tubes 42, 45 for feeding material to, and removing material from, the rotor 2, the tube 45 being axially clampable, so as to be subjected to the axial sealing forces between the head portions whilst being rotatable relative to at least one of the rotor 2 and the rotatable portion 37, 38, and the tube 42 being mounted to rotate with, and be movable axially relative to at least one of, the rotor and the rotatable portion so as to transmit torque between the rotor 2 and the head 3. The rotor 2 is releasably supported in a vacuum enclosure on a motor driven shaft 6 and the head 3 is mounted on a movable cover 4 of the enclosure. A core member 7 supported axially in the body 5 of the rotor has fluid passages 8, 9 and contains a fluid transfer plug 10. The member 7 is surrounded by a hollow member 14 containing passages 15a, 15b communicating with the passage 8 and passages 16 communicating with the passages 9, the passages 15a, 15b, 16 opening in a separation chamber 17 which contains septa dividing it into segments. An oil drain reservoir fitted below the bearing sleeve 22 of the stationary portion of the head comprises tubes 25 separated by a supporting tube 26 and bottom plug 27. The tube 26 has apertures for oil drainage from space A to space B. The part 29 of the stationary portion forms a sealing member spring-pressed against a rotary seal 38 carried by the bearing member 37 which is rotatably mounted in member 37 which in turn is rotatably mounted in member 22. Tube 42 is fixedly secured at its upper end within member 37 and at its lower end within plug 10 so as to transmit torque from rotor 2 to member- 37 whilst longitudinal stress on tube 42 is negligible since it is axially movable relative to the rotor. The annular passage 41 between tube 42 and member 37 is connected to the rotor by a tube 45 which is subjected compressively to the axial sealing forces of the head but is relieved of torsional stress which is taken up by tube 42. Tube 45 can rotate relative to the core member 7 and bearing member 37 if tube 42 is torsionally deformed. In operation, vacuum is produced in the enclosure and the rotor 2 is run at low speed. Water is pumped through a tube 33, passages 35, 39, tube 42 and passages 9, 16 and fills the rotor chamber 17 displacing air through passages 15a, passages 15b being blocked at this speed from passages 8 by an O-ring valve 46. The rotor speed is increased to open valve 46 centrifugally displacing air trapped in passages 15b. The speed is then reduced to close valve 46 and a liquid having a density gradient is fed, light end first, through a tube 34, passages 36, 40, 41, tube 45, passages 8 and 15a, to chamber 17 and displaces water from the chamber through passages 16 back through tube 33. The rotor speed is again increased to open valve 46 and a sample in a carrier liquid is fed through tube 33 and flows from passages 16 along the surface of the rotor member 14 and through passages 15b to tube 34. The sample particles migrate radially across the chamber according to their densities. The particles may be removed by slowing the rotor to close valve 46 and by passing a dense solution along tube 34 via passages 15a, displacing sample via passages 16 and out of tube 33. With a modified rotor construction, a sample may be continuously fed into, and discharged out of, the rotor at high speed and under vacuum. A spring-loaded ball valve may be used in place of the O-ring valve 46.