US3650465A - Discharge of solid particles from centrifugal machines - Google Patents

Discharge of solid particles from centrifugal machines Download PDF

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Publication number
US3650465A
US3650465A US876229A US3650465DA US3650465A US 3650465 A US3650465 A US 3650465A US 876229 A US876229 A US 876229A US 3650465D A US3650465D A US 3650465DA US 3650465 A US3650465 A US 3650465A
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United States
Prior art keywords
basket
particles
set forth
lip
centrifugal machine
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Expired - Lifetime
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US876229A
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English (en)
Inventor
Geoffrey L Grimwood
Duncan C Ferrier
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Thomas Broadbent and Sons Ltd
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Thomas Broadbent and Sons Ltd
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Application filed by Thomas Broadbent and Sons Ltd filed Critical Thomas Broadbent and Sons Ltd
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B04—CENTRIFUGAL APPARATUS OR MACHINES FOR CARRYING-OUT PHYSICAL OR CHEMICAL PROCESSES
    • B04B—CENTRIFUGES
    • B04B11/00—Feeding, charging, or discharging bowls
    • B04B11/02—Continuous feeding or discharging; Control arrangements therefor
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B04—CENTRIFUGAL APPARATUS OR MACHINES FOR CARRYING-OUT PHYSICAL OR CHEMICAL PROCESSES
    • B04B—CENTRIFUGES
    • B04B7/00—Elements of centrifuges
    • B04B7/02—Casings; Lids
    • B04B7/04—Casings facilitating discharge

Definitions

  • ABSTRACT A method and apparatus for modifying the flight of particles discharged from the lip of the basket of a centrifugal machine.
  • a pneumatic zone is created around the lip of the basket, and a series of gaseous jets are directed into this zone so as at least to reduce the radial component of velocity, considered in a direction radially outwardly of the basket, of particles discharged from the basket lip.
  • the particles may be allowed to fall, under the influence of gravity, from the pneumatic zone, or alternatively may be pneumatically conveyed from the centrifugal machine.
  • the present invention relates to centrifugal machines and is particularly concerned with the discharge of particles from the baskets of centrifugal machines such as centrifuges and centrifu gal separators.
  • a centrifugal machine consists of a centrifuge basket commonly in the form of a perforated hollow cone which basket is rotatably mounted at its apex on a set of bearings.
  • the machine includes a drive mechanism such as an electric motor, for driving the centrifuge basket.
  • a drive mechanism such as an electric motor, for driving the centrifuge basket.
  • the electric motor When the electric motor is operated and has brought the basket up to a preselected speed, slurry to be separated is introduced into the centrifuge basket.
  • the slurry separates, in known manner, into a liquor component and a solid particle component.
  • the liquor component passes through the perforations in the basket to be collected in a tank, or other collection vessel, and the solid particle component passes over the peripheral edge or lip of the basket to be discharged substantially tangentially therefrom.
  • a substantially cylindrical casing is spaced around the lip of the centrifuge basket, and the solid particle component of the slurry which as been discharged from the basket is arrested by this casing. Thereafter the solid particle component falls, under the influence of gravity, into a suitable collection vessel, often located outside the centrifugal machine itself.
  • the centrifugal machine can be mounted at any angle, but normally it is arranged either horizontally or vertically for convenience ofloading of the centrifuge basket.
  • a further disadvantage is that the solid particle component has tended to lodge in the walls of the cylindrical casing, thereby both reducing the number of particles collected, and also damaging the casing.
  • a method of modifying the flight of solid particles discharged from a centrifuge basket lip which comprises directing a series of gaseous jets into a pneumatic zone extending around the basket lip so as at least to reduce the radial component of velocity, considered in a direction radially outwardly of the basket, of particles discharged from said lip.
  • Thejets may be directed so as to cause the particles to move around the basket, either in the direction of rotation of the basket, or in the opposite direction.
  • the jets may be directed so as to directly oppose the flight of the particles from the basket lip.
  • thejets may be directed at an acute angle to the tangential direction from the basket lip so as not only to reduce the particle speed in the direction tangentially away from the basket lip but also to reverse the component of velocity of the particles in the circumferential direction of the basket to cause the particles to move around the basket in the opposite direction of rotation thereof.
  • thejets of air may have a lower velocity and may be directed at an angle which is related to the tangential direction from the rotor lip so as to afford to the jets a component of velocity which reduces the particle speed in the tangential direction away from the lip and also a component of velocity which serves to change the direction of flight of the particles to cause them to flow circumferentially in the direction of rotation of the basket.
  • the separated particles may be pneumatically conveyed away fromthe centrifugal machine.
  • the jets of air may be arranged to have a velocity exactly equal and opposite to that of particles discharged from the centrifuge basket.
  • the velocity of separated particles is reduced and the particles allowed to drop, under the influence of gravity, from the pneumatic zone.
  • a centrifugal machine in which the centrifuge basket is surrounded by a hollow casing defining a pneumatic zone, the inner periphery of which casing is open to a discharge lip on said basket for receiving particles discharged therefrom, and the outer periphery of which casing is connected to a manifold surrounding said casing, and means for establishing a series of jets of gas from said manifold to said pneumatic zone which jets are directed so as at least to reduce the radial component of velocity, considered in a direction radially outwardly of the basket, of particles discharged from said lip.
  • the means for establishing the jets of gas comprises a plurality of guide vanes located between the manifold and the casing.
  • the vanes may be arranged in a shallow annular passage connecting the inner periphery of the manifold with the outer periphery of the casing.
  • the vanes may be angled to the radial plane to impart to the jets of air the: required radial and circumferential velocity components to retard and/or deflect the particles, the radial velocity component being directed inwards towards the rotor and the circumferential velocity component either in or against the direction of rotation of the basket.
  • the vanes may be straight or curved in a similar manner to turbine blades.
  • the casing may be of gradually increasing cross-sectional area in a direction leading towards an outlet therefrom. (See dotted line in FIG. 1).
  • the casing may be of volute form.
  • the casing may increase in crosssection abruptly towards an outlet. (See FIG. 8).
  • a partial vacuum by vacuum pump at 37 in FIG. 1
  • gas under positive pressure may be admitted to the casing at one or more localities therealong.
  • the present invention not only reduces impact damage to centrifuged particles but also provides a simple mode of conveying centrifuged particles away from the centrifuge in a gas stream. Further the air or other gas used in the performance of the present invention may be heated in order to dry the particles incidentally with their retardation and/or their conveyance.
  • FIG. 1 is a partly cut-away perspective view of part of a centrifugal machine embodying one embodiment of the invention
  • FIG. 2 is a sectional elevation on the lines IIII of FIG. 1;
  • FIG. 3 is a partly cut-away plan view of the centrifugal machine illustrated in FIGS. 1 and 2;
  • FIGS. 4 and 5 are views similar to FIGS. 1 and 3 of a second embodiment of the invention.
  • FIG. 6 is a view similar to FIG. 5 illustrating a modification
  • FIG. 7 is a side sectional view illustrating a centrifugal machine embodying a third embodiment of the invention.
  • FIG. 8 is a side sectional view through Section A-A in FIG. 1 depicting the abrupt increase in cross-section ofthe casing.
  • FIGS. 1 to 3 there is shown a rotatable centrifuge basket 2 ofa centrifugal machine which as a peripheral edge or lip l.
  • the basket 2 is in the form ofa perforated hollow cone and is mounted for rotation on a set of bearings (not shown). Typical perforations are shown in the basket 2 of FIG. 7.
  • the centrifugal machine includes an electric motor (not shown) for driving the basket 2 in the direction of the arrow 10.
  • a hollow annual casing 3, defining a pneumatic zone 30, is arranged to extend around the basket 2.
  • the inner periphery of the casing 3 is open to the lip l of the basket 2 for receiving particles discharged from the lip in a manner to be described hereafter.
  • the outer periphery of the casing 3 is connected by a shallow annular passage 4 with the inner periphery of a toroidal manifold 5.
  • a plurality of steel vanes 6 are mounted in the passage 4, the vanes being directed at an acute angle with respect to tangents taken from the basket 2.
  • Pressurized air or other gas, is introduced into the toroidal manifold 5 from a duct 32 and the air distributes throughout the manifold 5 in known manner. If desired, the air may be heated to assist in the drying of particles separated by the basket 2.
  • the pressurized air passes between the vanes 6 to create a series ofjets of air, which are directed into the pneumatic zone 30, at an acute angle to tangential planes taken with respect to the lip 1 ofthe basket 2.
  • the casing 3 is of volute configuration, the deepest end of the volute leading to a conveyor duct 34 for conveying separated particles away from the centrifugal machine.
  • the electric motor is operated to take the basket 2 up to a selected speed of rotation. Slurry is then introduced into the basket 2 by an inlet pipe (not shown 36. As the basket rotates the slurry separates, in known manner, into a liquor component, which passes through the perforations in the basket 2 to be collected in a tank, (not shown) and a solid particle component. The solid particle component is discharged, substantially tangentially from the lip 1 into the pneumatic zone 30, when it comes under the influence of the jets of air which are defined between the vanes 6.
  • FIG. 3 illustrates the path 11 taken by a single particle after its discharge from the lip 1.
  • the jets of air are arranged to have a higher velocity than that ofthe particles and the jets not only reduce the particles speed in the direction tangentially away from the lip 1 but also reverse the component of velocity of the particle in the circumferential direction of the basket. The particle is thus caused to move around the basket 2, as indicated by dotted line 7, in the opposite direction to the direction of rotation of the basket 2.
  • the particle passes around the volute casing 3, and falls from the pneumatic zone 30, eventually to be removed from the centrifugal machine by the conveyor duct 34, for drying or packaging. If desired, heated air may be passed into the manifold 5, thus assisting in the drying of the particle components.
  • the embodiment described hereinabove is particularly suitable for centrifuging high velocity particles.
  • a typical use for the embodiment is in the extraction of sugar crystals from low grade massecuite.
  • a 30 inch diameter basket is used which is rotated at approximately 1,800 r.p.m. imparting a speed of approximately 250 ft./sec. to each crystal as it leaves the basket.
  • vanes 14 of FIGS. 4 and 5 are angled at an obtuse angle to the tangential direction of flight of the particles from the basket lip 1 so as to oppose the flight of the particles in the radially outward direction and to enhance the flight of the particles in the circumferential direction to cause them to move circumferentially around the casing 3 in the direction of rotation of the basket 2, as illustrated in FIG. 5.
  • the casing 3 is much shallower and itself provides the shallow annular passage in which the vanes 14 are located.
  • the flight of the particles as modified by jets of air issuing from between vanes 14 is indicated by the broken line 15.
  • FIGS. 4 and 5 is particularly suitable for low velocity particles, for example, in the separation of balls, such as polystyrene balls at a velocity of approximately ft./sec.
  • FIG. 6 illustrates a form of construction which is similar to that of FIGS. 4 and 5 except that it incorporates vanes 16 which are curved, in a similar way to turbine blades, instead of being straight. Curved vanes could of course be used in the embodiment of FIGS. 1 to 3 instead of straight vanes.
  • curved blades One advantage of curved blades is that the pressurized air from passing the manifold 5 is gradually deflected, and this tends to reduce the pressure drop across the vanes.
  • the third embodiment of the invention illustrated in FIG. 7 is similar to the first embodiment and again like reference numerals have been used to designate like parts with those of FIGS. 1 to 3.
  • the casing 3 is shallow over its inner periphery surrounding the lip l, but its outer periphery adjacent the shallow passage 4 is deep to enable particles arrested by the jets of air to flow freely under gravity as illustrated by the broken lines 24.
  • the particles flow through the casing 3 to a storage container, or to a conveyor.
  • the jets of air are arranged to have a velocity substantially equal and opposite to that of particles discharged from the lip 1.
  • the velocity of separated particles is thus reduced and the particles fall, under the influence of gravity, from the pneumatic zone 30 into a container or onto a conveyor.
  • the liquor component is removed through a pipe 25 in known manner.
  • a method of modifying the flight of solid particles discharged from the lip of said centrifuge basket, said particles having a radial component of velocity considered in a direction radially outwardly of the basket wherein the improvement comprises creating a pneumatic zone extending around said basket lip and directing a series ofjets of gas into said pneumatic zone so as at least to reduce the radial component of velocity of the particles discharged from said lip.
  • a centrifugal machine having a perforated frustoconical centrifugal basket with a discharge lip and including means for introducing into said basket slurry to be separated, wherein the improvement consists essentially of:
  • a centrifugal machine as set forth in claim 9 wherein the means for establishing the plurality ofjets of gas comprises a plurality of guide vanes.

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  • Centrifugal Separators (AREA)
US876229A 1968-11-16 1969-11-13 Discharge of solid particles from centrifugal machines Expired - Lifetime US3650465A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB54475/68A GB1293761A (en) 1968-11-16 1968-11-16 Improvements in or relating to the discharge of solid particles from centrifugal machines

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US3650465A true US3650465A (en) 1972-03-21

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US876229A Expired - Lifetime US3650465A (en) 1968-11-16 1969-11-13 Discharge of solid particles from centrifugal machines

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US (1) US3650465A (de)
BE (1) BE741725A (de)
CH (1) CH495782A (de)
DE (1) DE1957607A1 (de)
FR (1) FR2023457A1 (de)
GB (1) GB1293761A (de)
NL (1) NL6917205A (de)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3973984A (en) * 1974-11-26 1976-08-10 Braunschweigische Maschinenbauanstalt Continuously operable sugar centrifuge
US4008098A (en) * 1974-11-11 1977-02-15 Braunschweigische Maschinenbauanstalt Process and apparatus for continuously producing a high concentration sugar solution
US4405265A (en) * 1981-03-18 1983-09-20 Beloit Corporation Method and apparatus for the continuous transfer of particulates from a liquid conveying medium to a gaseous conveying medium
WO1992011947A1 (en) * 1991-01-14 1992-07-23 W.D.T. (Engineers) Pty. Ltd. Centrifuge solids deflector

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2849927B2 (de) * 1978-11-17 1980-11-27 Maschinenfabrik Buckau R. Wolf Ag, 4048 Grevenbroich Kontinuierlich arbeitende Zucker-Zentrifuge mit einer Einmaischvorrichtung
EP0031549A1 (de) * 1979-12-20 1981-07-08 Verenigde Machinefabrieken Stork N.V. Kontinuierlich arbeitende Zentrifuge

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US617865A (en) * 1899-01-17 skinner
US2331850A (en) * 1940-11-27 1943-10-12 William N Smith Granular material classieier or purifier
US2992140A (en) * 1958-10-08 1961-07-11 Frank C Gaiennie Process for removing sugar from raw sugar cane
US3011696A (en) * 1947-07-23 1961-12-05 Boyland Donald Arthur Centrifuges
US3107217A (en) * 1958-01-23 1963-10-15 Muller Hans Arrangement for the continuous separation of solids and liquids by filtration
US3238063A (en) * 1962-08-03 1966-03-01 American Factors Ass Ltd Continuous centrifugal apparatus and method of continuously separating granular crystals therewith
US3301708A (en) * 1964-05-05 1967-01-31 Buckau Wolf Maschf R Apparatus for separating crystals from sugar syrup

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US617865A (en) * 1899-01-17 skinner
US2331850A (en) * 1940-11-27 1943-10-12 William N Smith Granular material classieier or purifier
US3011696A (en) * 1947-07-23 1961-12-05 Boyland Donald Arthur Centrifuges
US3107217A (en) * 1958-01-23 1963-10-15 Muller Hans Arrangement for the continuous separation of solids and liquids by filtration
US2992140A (en) * 1958-10-08 1961-07-11 Frank C Gaiennie Process for removing sugar from raw sugar cane
US3238063A (en) * 1962-08-03 1966-03-01 American Factors Ass Ltd Continuous centrifugal apparatus and method of continuously separating granular crystals therewith
US3301708A (en) * 1964-05-05 1967-01-31 Buckau Wolf Maschf R Apparatus for separating crystals from sugar syrup

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4008098A (en) * 1974-11-11 1977-02-15 Braunschweigische Maschinenbauanstalt Process and apparatus for continuously producing a high concentration sugar solution
US3973984A (en) * 1974-11-26 1976-08-10 Braunschweigische Maschinenbauanstalt Continuously operable sugar centrifuge
US4405265A (en) * 1981-03-18 1983-09-20 Beloit Corporation Method and apparatus for the continuous transfer of particulates from a liquid conveying medium to a gaseous conveying medium
WO1992011947A1 (en) * 1991-01-14 1992-07-23 W.D.T. (Engineers) Pty. Ltd. Centrifuge solids deflector

Also Published As

Publication number Publication date
BE741725A (de) 1970-05-14
NL6917205A (de) 1970-05-20
GB1293761A (en) 1972-10-25
DE1957607A1 (de) 1970-11-19
FR2023457A1 (de) 1970-08-21
CH495782A (de) 1970-09-15

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