US3199681A

US3199681A - Centrifuge

Info

Publication number: US3199681A
Application number: US138701A
Authority: US
Inventors: William J Kirkpatrick
Original assignee: Pennsalt Chemical Corp
Current assignee: Pennwalt Corp
Priority date: 1961-08-02
Filing date: 1961-08-02
Publication date: 1965-08-10
Anticipated expiration: 1982-08-10

Description

Aug. 10, 1965 CENTRIFUGE 2 Sheets-Sheet 1 Filed Aug. 2, 1961 M M 0 4 4 z a, 6 4 6 4 w a a 4 g f 5 a 3 r u N w 9 a w i 2 mum h a a 5 14770/P/1/EX g- 10, 1965 w. J. KIRKPATRICK 3,199,681

CENTRIFUGE Filed Aug. 2, 1961 2 Sheets-Sheet 2 INVENTOR. w/u MM J. HIP/(PA TA /CA ATTOK/VEX United States Patent William .l. Kirkpatrick, Springfield, Pa, assignor to ennsait fihemieals Corporation, a corporation of ennsylvania Filed Aug. 2, 1961, Ser. No. 138,761 Claims. (til. 21il374) This invention relates generally to the separation of solids from liquids by centrifugal force.

More specifically, this invention is concerned with apparatus adapted to separate solids from liquid, the apparatus comprising a perforate rotor enclosing a screw conveyor. The rotor and the conveyor are driven in the same direction but at dflferent speeds whereby the conveyor scrolls solid material along the inside surface of the rotor from the feed to the discharge end. in such devices the feed mixture has been introduced from a stationary feed pipe into a central opening in one end of the rotating conveyor and has been thrown outwardly through more or less radial feed passages into the annular chamber between the conveyor and the perforate rotor. Liquid in the mixture has been hurled out through the perforations in the rotor while the solids have been scrolled along to discharge in relatively dry condition at the discharge end of the rotor.

It has been noted in using apparatuses of this type in the prior art that turbulence is created in the zone in the conveyor at which the feed leaves the stationary feed pipe. Such turbulence is doubtless caused (1) by the surge of feed against the obstacle formed by the diverging feed passages in the conveyor, and (2) by the sudden radial acceleration demanded of the feed by the rotating Walls of the feed passages. The former of these two causes is compounded in installations iri which feed is delivered to the apparatus directly from a continuous pressure cooker and steam pressure therefrom blasts the surge of feed into the apparatus.

The turbulence created has caused a back flow and splashing projecting feed upward into the annular area between the feed tube and the conveyor. Even worse, feed has passed upward in this annual area, over the top of the conveyor and outward, contaminating the separated liquid discharge of the apparatus with feed including, of course, oversize solid particles. In order to avoid this undesirable contamination of the separated liquid discharge by the feed mixture, it has been necessary in the past to stint the rate at which the feed mixture has been delivered to the machine.

It is an object of the present invention to provide improved seal means between the feed tube and the conveyor in an apparatus as generally described above. in preferred form the seal is adjustable to accommodate changes in relative position of the conveyor and rotor.

This invention embodies other novel features, details of construction and arrangement of parts, which are hereinafter set forth in the specification and claims, and illustrated in the accompanying drawings, wherein:

FIGURE 1 is a fragmentary sectional view of an apparatus embodying the invention;

FIGURE 2 is an enlarged View of a portion of PH:- URE 1, pointing out more particularly the area of invention; and

FIGURE 3 is an enlarged fragmentary sectional view taken on the line 3-3 of FIGURE 2.

Briefly, in a centrifuge comprising a frame mounting for rotation at different speeds, a perforate rotor and a screw conveyor within the rotor, t.e conveyor having an opening in one end to receive a feed mixture, and a stationary feed tube projecting into the opening, the invention comprises improved seal means including an outward radial face on the feed tube spaced axially from the dis- "ice charge end thereof, the face being spaced closely adjacent the conveyor to preclude passage of feed mixture therebetwce Referrin" more specifically to the drawings, an apparatus embodying the invention is shown in FIGURE 1 and designated 1%. It comprises a frame 12 including drive means and transmission means providing coaxial rotary motion at different speeds through a spider 1-; to rotor 16, and directly to a screw conveyor 18.

As shown, the rotor it? comprises a perforate frustoconical basket 20 defined by a plurality of coaxial ring elements Ella, triangular in cross section and spaced from each other as is well known in the art. The ring elements are held in appropriate relation by supports 22 to the upper ends of which are secured the annular rim 24. The inside surface of the rotor is faced with sheet 26 of metal or the like having perforations of a character as will be described later.

The conveyor 18, mounted substantially coaxial of the rotor, comprises a frusto-conical body element 28 having the flights 355 secured to its outside surface. A head 32 is secured to the top of the lower end of the conveyor and features a rinse cap 33. The head 32. presents a central opening 3% which is surrounded by a radial annular face 36. The opening 34 extends downwardly toward the cap 33 and communicates with a plurality of downward generally radial passages 38. The passages 38 terminate out wardiy in openings into the annular chamber between the conveyor 18 and the rotor 15.

The frame 12 mounts a cover element 4!) which presents at its upper end a fiat annular surface having a central aperture 42 disposed in alignment over the opening 34- in the conveyor. As shown, the surface receives a flanged conduit 44, the lower flange of which is bolted to the cover member 4 3, and the upper flange of which is bolted to a mating flange at the end of a supply pipe 4. It has been found advantageous in the past to form at least a portion of the conduit 44 from a transparent plastic such as Lucite in order that the flow of feed mixture during operation may be visually noted.

Rinse liquid may be supplied to the conveyor through pipe 47 for operation in a manner well known. For simplicit rinse nozzles are not shown in the conveyor in the accompanying drawing.

Turning now to the area of the apparatus shown in FIGURES 1 and 2 which embodies the invention, the transition sleeve is designated 48. It comprises a tubular element shown best in FIGURE 2 to present a chamfered inner edge St at its upper end to help reduce turbulence as feed flows thereinto. About the outer surface of the transition sleeve are a pair of spaced grooves receiving O-rings 52 normally in snug sealing engagement with the inside surface of conduit 44, but still permitting axial adjustment of the transition sleeve 48 within the conduit 44. Between the O-rings 52 the outer surface of the sleeve 43 is formed with a reduced zone 54. Cooperating in this reduced zone with the sleeve 48 is a set screw 5% disposed radially in the wall of conduit 44 adjacent its lower flange. As shown, the set screw 56 may be tightened against the sleeve 48 in the zone 54 to fix the relative position of the telescoping elements.

Intermediate its upper and lower ends the transition sleeve 48 is provided with an outwardly directed annular flange 58. The underside of flange 58 preferably carries an upward annular channel into which is received a flat resilient gasket oil. The under surface of the gasket as has an annular radial face 62.

The nature of the gasket 69 must be, because of its position, adjacent the conveyor 18, extremely durable. At the same time the gasket ea must have ability to yield rather than do injury to the conveyor should the two elements contact.

After much experimentation it has been found that a material exceptionally suitable for use as gasket 6t} comprises 25% glass-filled polytetrafiuoroethylene. This plastic has a desirably low coefficient of friction rendering it almost slippery in the present use, a quality obviously desirable. When glass-filled, it exhibits extreme resistance to wear. It should be understood that while glass-filled polytetrafluoroethylene is the preferred mate- 7 rial for the gasket, the invention may be practiced retaining most of its benefits by forming the gasket of other materials. The gasket is at least preferably formed of one of the resilient plastics, although it is contemplated to form the gasket of carbon, heavy water-laid fabric, or even of soft metal such as lead or Babbitt metal.

As shown in FIGURES 1 and 2 the under face 62 of the gasket is fixedin position by the set screw 56 to be only slightly above the radial annular face 36 at the top of the conveyor.

Referring to FIGURE 3, the sheet 26 is formed with uniformly spaced perforations 64. In a preferred form the perforations are conical, being of smaller diameter toward the inside of the apparatus and flaring outwardly.

., This shape provides an expedient well known in the art for precluding the blockage of the openings by solid material lodging therein. Obviously solid particles would be more likely to wedge into cylindrical openings.

In a preferred form the passages in the openings 64 of sheet 26 are circular. The diameter of these passages control the size of solids admitted through the sheet 26. Hence, in order to prevent passage of solids of size greater than those passed by openings 64, the space between face 36 and face 62 of the gasket must not be greater than the diameter of the passages. Preferably, because the space between the

faces

36 and 62 is continuous and could therefore admit fiat oversized solids if properly oriented with respect to the space, the face 62 is brought down closer to the face 36 than a diameter of the passage through an opening 64-, to lessen chances of such admittance. It should be understood that very occasional passage of such fiat over-sized solids through the continuous space can usually be tolerated.

Thus, in the preferred form, the space between face 62 and face 36 is of a thickness (1, while the diameter of the passage through opening is of a distance (1+, greater than thickness a.

For illustration only and not by way of limitation, the following examples are presented.

Example I In an apparatus embodying the invention in which the diameter of the base of the conveyor measured across the edges of tie flights was about 17 inches, the rotor was operated at 2800 r.p.m. The edges of the flights 30 were positioned to clear the screen by 0.043" at the upper part of the conveyor and by 0.030" at the lower end of the conveyor. The passages through the openings 64 were .020", and the face 36 was within .005" of the face 62 of the glass-filled polytetrafluoroethylene gasket 69.

Tomato slurry including skins, stems, seeds, pulp and juice was fed through conduit 44 at the rate of 20 tons per hour. Dry pomace was discharged through the annular opening at the base of the apparatus through spider 14 at the rate of 1,371 pounds per hour. Pulp and juice were discharged through the perforations in the rotor. For practical purposes no oversizcd solids Were present in the liquid discharge.

Example 11 charge causing seeds to contaminate the clarified juice making it unfit for sale.

By mounting the transition sleeve 48 adjustably within the conduit 44 as shown in FIGURES 1 and '2 it may be adjusted up and down to establish proper relation with respect to the conveyor which itself is axially adjustable. Adjustability of the conveyor is necessary to accommodate different thicknesses of sheet 26 and to obtain various clearances from the sheet depending on the nature of the product worked.

It will be obvious to those skilled in the art that the invention is not limited to apparatuses of the frustoconical shape described and shown. Moreover, the invention can be embodied in apparatus having other than vertical axis.

Additionally, while the preferred arrangement is shown in FIGURE 1, the organization may be altered by eliminating the upper part of the conveyor 18 including the walls of the passages 38 and portions thereabove. Rim 24 of the rotor 16 can then be extended inward to present a radial annular surface opposing the face 62 much as surface as does in the embodiment disclosed in the drawings. Such an altered embodiment of the invention retains many of the benefits of the apparatus of FIGURES While the faces 35 and 62 have been described as radial, they are so formed chiefly for convenience and simplicity, and to avoid any possibility of interference when the conveyor moves laterally at its critical speeds. It is understood, however, that without losing all benefits of the invention, these opposing surfaces may be cooperating surfaces of rotation about the axis of lines of various configurations. The surfaces may slant up or down from the axis, or even be concentrically serrated in a manner by which they mate with and complement each other.

Similarly, it should be understood that the openings in the sheet 26 need not be circular. They may be triangular or rectangular or in the shape of another geometric figure. In each case, the space between the

faces

36 and 62 is no greater than and preferably less than the diameter of the largest circle which can be inscribed within the figure.

Thus having more particularly described my invention, it is to be understood that this description is by way of illustration, and that changes, omissions, additions, substitutions, and/or modifications may be made without departing from the spirit thereof. Accordingly, it is intended that the patent-shall cover by suitable expression in the claims the various features of patentable novelty that reside in the invention.

I claim:

1. In a centrifuge comprising a perforate frusto-conical rotor element and a correspondingly frusto-conical conveyor element nesting within said rotor, means for driving said elements at different respective speeds, said elements defining a centrifuging chamber, said chamber having an inlet comprising an opening in the smaller end of one of the elements, the opening being defined by a generally radial annular surface, the opening extending to the periphery of the conveyor, a tubular feed conduit supported axially of the rotor adjacent the opening; the improvement of a transition sleeve telescopically associated with said tubular feed conduit and slidably extending into the opening in said one element, said sleeve having an annular outwardly extending flange intermediate its ends, the face of said flange adjacent said opening mounting a resilient ring with a fiat substantially radial surface opposing and spaced from said generally radial annular surface about said opening a distance 'no greater than the largest dimension across a perforation in the perforate rotor element, said sleeve being so constructed and arranged as to be axially adjustable with respect to said tubular feed conduit and said opening, and means for fixing the relative axial position of said sleeve.

2. In a centrifuge comprising a frame mounting for rotation at diflerent speeds respectively, a perforate frusto-conical rotor and a correspondingly frusto-conical screw conveyor nesting within said rotor, said conveyor having in its smaller end a central opening defined by a substantially radial annular surface, the opening extending downward and terminating in delivery ports in the periphery of said conveyor, said frame including a cover element having an aperture in alignment over the central opening in the conveyor, an unstading tubular element mounted on said cover in said aperture; the improvement of a transition sleeve telescopically received into said tubular element in snug engagement and slida'bly extending down into the opening in said conveyor, said sleeve having an annular outwardly extending flange intermediate its ends, the underside of said flange having bonded thereto a resilient ring with a fiat substantially radial undersurface spaced above said radial annular surface a distance no greater than the largest dimension across a perforation in the rotor, said sleeve being so constructed and arranged as to be axially adjustable with respect to said tubular element and said opening, and means for fixing the relative axial position of said sleeve.

3. A centrifuge as described in claim 2 wherein the said distance is no greater than the diameter of the largest circle that can be inscribed in a perforation in the rotor. 4;. A centrifuge as described in claim 2 wherein the perforations in the rotor are in the shape of a circle and tie distance is less than the diameter of the circle.

5'. A centrifuge as described in claim 2 in which said ring is made of glass-reinforced polytetrafiuoroethylene.

References Qited by the Examiner UNITED STATES PATENTS 604,622 5/98 Lobdell et al. 285293 3,011,6 I7 12/61 Elsken 210380 FOREIGN PATENTS 1,188,056 3/59 France. 1,215,693 11/59 France.

OTHER REFERENCES Heinz Huster: German printed appiication No. 1,059,841, June 9 (-correspondin g Great Britain,

884,768, December 1961).

REUBEN FRIEDMAN, Primary Examiner.

HERBERT L. MARTIN, Examiner.

Claims

1. IN A CENTRIFUGE COMPRISING A PERFORATE FRUSTO-CONICAL ROTOR ELEMENT AND A CORRESPONDINGLY FRUSTO-CONICAL CONVEYOR ELEMENT NESTING WITHIN SAID ROTOR, MEANS FOR DRIVING SAID ELEMENTS AT DIFFERENT RESPECFIVE SPEEDS, SAID ELEMENTS DEFINING A CENTRIFUGING CHAMBER, AID CHAMBER HAVING AN INLET COMPRISING AN OPENING IN THE SMALLER END OF ONE OF THE ELEMENTS, THE OPENING BEING DEFINED BY A GENERALLY RADIAL ANNULAR SURFACE, THE OPENING EXTENDING TO THE PERIPHERY OF THE CONVEYOR, A TUBULAR FEED CONDUIT SUPPORTED AXIALLY OF THE ROTOR ADJACENT THE OPENING; THE IMPROVEMENT OF A TRANSITION SLEEVE TELSCOPICALLY ASSOCIATED WITH SAID TUBULAR FEED CONDUIT AND SLIDABLY EXTENDING INTO THE OPENING IN SAID ONE ELEMENT, SAID SLEEVE HAVING AN ANNULAR OUTWARDLY EXTENDING FLANGE INTERMEDIATE ITS ENDS, THE FACE OF SAID FLANGE ADJACENT SAID OPENING MOUNTING A RESILIENT RING WITH A FLAT SUBSTANTIALLY RADIAL SURFACE OPPOSING AND SPACED FROM SAID GENERALLY RADIAL ANNULAR SURFACE ABOUT SAID OPENING A DISTANCE NO GREATER THAN THE LARGER DIMENSION ACROSS A PERFORATION IN THE PERFORATE ROTOR ELEMENT, AID SLEEVE BEING SO CONSTRUCTED AND ARRANGED AS TO BE AXIALLY ADJUSTABLE WAS RESPECT TO SAID TUBULAR FEED CONDUIT AND SAID OPENING, AND MEANS FOR FIXING THE RELATIVE AXIS POSITION OF SAID SLEEVE.