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Publication numberUS3053391 A
Publication typeGrant
Publication dateSep 11, 1962
Filing dateAug 17, 1959
Priority dateAug 17, 1959
Publication numberUS 3053391 A, US 3053391A, US-A-3053391, US3053391 A, US3053391A
InventorsGeorge L Nelson
Original AssigneeBird Machine Co
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Apparatus for screening
US 3053391 A
Abstract  available in
Images(2)
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Claims  available in
Description  (OCR text may contain errors)

Sept. 11, 1962 N LSON APPARATUS FOR SCREENING 2 Sheets-Sheet 1 Fi led Aug. 17, 1959 Sept. 11, 1962 G. L. NELSON 3,053,391

APPARATUS FOR SCREENING Filed Aug. 17, 1959 2 Sheets-Sheet 2 ZZZ Claims. (Cl. 2l03tl4) This invention relates to a device for screening liquid suspensions of solid particles and pertains more specifically to a device for screening aqueous paper pulp suspensions to remove fibers or other particles which are oversized or which have higher densities than the acceptable particles.

One object of the present invention is to provide a screen device which includes means for subjecting a liquid suspension to centrifugal forces of substantial magnitude of the order of several times the force of gravity and for continuously withdrawing a fractional portion of the suspension while so subjected to centrifugal forces in advance of its passage through a screen.

Another object is to provide a device of the type described which is of simplified construction and which is adapted to subject a liquid suspension both to centrifugal action and to a screening action.

Still another object of the present invention is to provide a screening device of improved construction capable of more effective separation of fibers or other particles of varying size and density.

Other and further objects will be apparent from the drawing and from the description which follows.

In the drawing:

FIG. 1 is a view in side elevation partly broken away and in section showing one embodiment of the present invention;

FIG. 2 is a view in vertical section taken along the line 22 of FIG. 1;

FIG. 3 is a View in cross section taken along line 33 of FIG. 1; and

FIG. 4 is a view in cross section taken along line 44 of FIG. 1.

Lin the embodiment shown in the drawing, the device comprises a main frame on which is mounted an annular U-shaped vessel having fixed inner and outer walls 12, 14. Outer wall 14 is preferably bulged outwardly at the right hand side as seen in FIG. 1 for reasons which will be explained below. Mounted within the annular vesses is a circular trough 16 from which leads an outlet 18 for rejected particles. Extending upwardly from the inner and outer margins of trough 16 are concentric generally cylindrical wall members 20, 22. Wall member 22 consists of a screen adapted to pass through its perforations the desired particles of paper fiber or the like. The upper end of screen 22 is secured to a sealing ring 24 which in turn is secured to a flange at the upper end of outer wall 14. Extension 26 may be secured to wall member 14 by any suitable means, as by bolting through mating flanges. Because the diameter of screen 22 is less than the diameter of extension 26, ring 24 forms a radially inwardly projecting baffle or shoulder which is inwardly offset from the inner face of extension 26. Immediately above ring 24 there is provided means for continuously withdrawing a fractional portion of the contents of the device tangentially which takes the form of a pipe 28 provided with throttle valve 30.

Inner wall 20 preferably is in the form of a screen, as shown in the embodiment illustrated in FIG. 1, although part of all of it may be a smooth imperforate wall if desired. The upper end of screen 20 is secured to a sealing ring 3-2 which together with a fixed housing 34 is secured to a flange at the upper end of inner wall Patented Sept. 11, 1962 jacent the upper end of extension 26 there is provided main inlet 36 which i disposed tangentially of extension 26 and arranged to introduce a stream of liquid suspension to flow in a spiral path about the inner face of extension 26 downwardly toward outlet 18. Supplemental housing 38 is provided to close the upper end of extension 26 and to confine the stream of suspension introduced through inlet 36 to an annular path of restricted width. Supplemental housing 38, inner wall 20, extension 26, and screen 22 together form an annular chamber through which the stream of liquid suspension flows in spiral fashion.

Means is provided for clearing the inlet face of screens 20 and 22 in the form of pairs of hydrofoils 40, 42 secured to ring 41 and to supporting arms or spider 44 which in turn is secured to the upper end of drive shaft 46 mounted in bearings 48, 50 to extend through waterpurged seal assembly 51 and driven from any suitable source of power (not shown) by means of a multiple V-belt drive 52. Hydrofoils 4t), 42 are mounted to be driven in a circular path which is slightly spaced from the inlet faces of the respective screens Zll, 22, the spacing being of the order of to A2 in. It will be understood that three or more hydrofoils may be mounted to act on each screen if desired, although two only are shown in the embodiment illustrated in the drawing. Means for introducing a supplemental supply of liquids such as water into the suspension as it passes across the face of the screens is provided in the form of an inlet 54 which opens into the space between screens 20, 22 to deliver the lisuid into a zone which is beyond the withdrawal means 28, 30 in the direction of the outlet 18. A main outlet 56 for the accepted stock opens from the space between inner wall 12 and screen 20 on the one hand and between outer wall 14 and screen 22 on the other hand. These spaces serve to receive the accepted screened stock which passes through screens 20, 22 and are enlarged as they approach outlet 56 to accommodate the screens toward outlet 56.

In operation of the device a supply of the liquid suspension such as paper pulp which is to be cleaned by the removal of oversized or high-density particles such as shives, dirt, iron rust and the like is introduced at a high velocity through inlet 36, being thus delivered into a spiral path winding its way downwardly within the annular chamber formed between extension 26, screen 22, and inner wall 38, 2%. [By proper control of the velocity of the suspension during its spiral passage, the material is subjected to a centrifugal force of the order of several times the force of gravity, so that the heavier oversized particles are thrown outwardly toward the inner face of extension 26. When inner wall 20 is itself a screen, as in the preferred embodiment, the desired fraction of the suspension passes readily through this screen with a minimum of blocking or clogging of the screen apertures with dirt particles. inasmuch as the fibrous particles present in paper pulp suspensions frequently have lengths several times the diameter of the screen apertures, it is essential that some means be provided to clear the inlet face of the screen at frequent intervals and to prevent the building up of a mat of fibres which would prevent flow of the suspension through the screen. This clearing is accomplished by the rapid and repeated passage of foils 40 across the inlet face of the screen, the passage of these foils serving to provide a pressure pulse at the screen face to create a momentary reversal of flow through the screen, thus removing any fibrous particles which have tended to mat over the apertures.

As the liquid suspension continues its downwardly spiraling flow, it reaches the shoulder or bafile formed by sealing ring 24 which serves to restrain further downward passage of the heavy oversized particles which have been thrown outwardly by centrifugal force. These particles are thus constrained to pass outwardly with the fractional portion of the suspension which is continuously withdrawn through pipe 28. These particles are thus prevented from ever reaching screen 22, making the operation of this screen more eifective. As the suspension continues to pass downwardly in the device across the face of screen 22, the desired particles pass through the screen, the inlet face of the screen being maintained clear by the repeated passage of foils 4-2, 42 in the same manner that the passage of foils 40, 40 maintains the face of screen 20 clear. Because the liquid suspension increases in consistency while it is being subjected to centrifugation and screening, separation of the undesired particles from the suspension becomes slower and more difiicult as the suspension approaches the bottom of screen 22. Accordingly, a stream of liquid, which may be water in the case of an aqueous pulp suspension, is introduced through supplimental inlet 54 to dilute the suspension and facilitate the final stages of the screening operation.

The accepted stock which passes through screens 20 and 22 is collected in the receiving chambers formed behind these screens by walls 12, 14 and then is passed outwardly through main outlet 56. The bulg of outer Wall 14 as it approaches outlet 56 provides the necessary increasing space required to accommodate the increasing volume of stock received from the screen as the accepted stock flows through the receiving chambers to the outlet. The portion of the suspension which is rejected by screens 20, 22 passes downwardly into the gutter or channel 16, whence it is removed through outlet 18.

The device combines in a single apparatus the operations and functions of a centrifuge as well as a screen. Inasmuch as the centrifugal operation occurs in advance of the outer screen 22, it renders the operation of this screen much more efficient than would otherwise be the case, reducing the load of oversized particles which normally would have to be rejected by screen '22. The device also makes it possible to introduce liquid such as water through supplemental inlet 54 in order to reduce the consistency of the suspension adjacent the lower ends of screens 20, 22 without risk of washing through the screens the undesired, heavy dirt particles.

Although a specific embodiment of the invention has been described herein, it is not intended to limit the application solely thereto, but to include all of the obvious variations and modifications within the spirit and scope of the appended claims.

What is claimed is:

"1. A device for treating aqueous suspensions containing particles of solid material which comprises a fixed cylindrical screen forming a portion of the outer wall of a chamber having an inner wall concentric with said outer wall to form an annular chamber, an inlet for introducing a stream of liquid suspension at one end of said chamber to flow in a spiral path therethrough, an outlet for rejected suspension at the other end of said chamber, means disposed radially outwardly of said screen for receiving accepted suspension after its passage through the screen, means for continuously withdrawing a fractional portion of said suspension through said outer w ll between said inlet and said screen, a baffie fixed to and extending radially inwardly from said outer wall, said bafile being disposed immediately beyond said withdrawal means in the direction of said outlet, and means extending into said chamber for clearing the inlet face of said screen. P

4. A device as defined in claim 1 in which the diameter of said screen is less than the diameter of the preceding portion of said outer wall between said inlet and said screen, and said bafile comprises an imperforate continuous shoulder joining said screen and said preceding outer wall portion.

5. A device as defined in claim 1 in which means is provided for introducing a supplemental supply of liquid into said chamber in a Zone beyond said withdrawal means in the direction of said outlet.

References Cited in the tile of this patent UNITED STATES PATENTS 762,867 Allen June 21, 1904 2,356,289 Wells Aug. 22, 1944 2,598,322 Vokes May 27, 1952 2,975,899 Cannon et al Mar. 21, 1961 FOREIGN PATENTS 545,191 Germany Feb. 26, 1932 1,000,246 France Oct. 10, 1951

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US762867 *Jul 23, 1902Jun 21, 1904Henry A AllenOre-separator.
US2356289 *Feb 17, 1942Aug 22, 1944Wells Harold DonaldPulp screen
US2598322 *Oct 25, 1946May 27, 1952Vokes LtdPorous filter
US2975899 *Apr 16, 1957Mar 21, 1961Bird Machine CoScreening device
DE545191C *Dec 17, 1927Feb 26, 1932Gustav SchlickFiltervorrichtung fuer Fluessigkeiten
FR1000246A * Title not available
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US3145165 *Oct 23, 1961Aug 18, 1964Sandison Alexander GreswoldePulp screens
US3159572 *May 23, 1962Dec 1, 1964Ranhagen Ernst Gustaf RaneMeans for the straining, fractionation and concentration of solids, e. g., cellulosefibres, suspended in a liquid
US3174622 *Jan 17, 1961Mar 23, 1965Lamort E & MApparatus for cleaning liquids containing in suspension solid particles and particularly cellulosic pulps
US3255883 *Feb 18, 1963Jun 14, 1966Bird Machine CoPulp screen with discharge receptacle
US3718258 *Oct 21, 1970Feb 27, 1973Gen Motors CorpContaminant separation
US3786918 *Aug 27, 1971Jan 22, 1974Finckh H Metalltuch MaschinenfPressure filter for fibrous suspensions
US5009774 *Oct 30, 1989Apr 23, 1991Beloit CorporationPulseless screen
US6030531 *Jul 14, 1998Feb 29, 2000Gershenson; MosheFilter element assembly
US6125826 *Dec 17, 1998Oct 3, 2000Societe Nationale D'etude Et De Construction De Moteurs D'aviationSelf-washing device for separating and filtering solid particles from a flow of liquid, and use of the device in a fuel injection circuit
US6238560Jan 12, 2000May 29, 2001Moshe GershensonCollapsible filter element assembly
US6511598May 23, 2001Jan 28, 2003Moshe GershensonConcentrically arranged filter element assembly
US6585892Oct 8, 2002Jul 1, 2003Moshe GershensonConcentrically-arranged flexible media and support basket with second stage cartridge filter
US6585893Oct 8, 2002Jul 1, 2003Moshe GershensonConcentrically-arranged, multi-sleeve bag-type filter element assembly
US6631809Feb 2, 2001Oct 14, 2003Andritz AgInfeed branch having axis, rotatable rotor, and stationary installation
US6669025Feb 2, 2001Dec 30, 2003Andritz AgScreen
US6706198Oct 8, 2002Mar 16, 2004Moshe GershensonWith use of collapsible polypropylene assembly; for bag and cartridge filters
US6712967Oct 8, 2002Mar 30, 2004Moshe GershensonLiquid filter assembly with concentric filter sleeves of bag-type media
US7001517Oct 8, 2002Feb 21, 2006Moshe GershensonCollapsible filter element
US7837875Aug 29, 2006Nov 23, 2010Eaton CorporationFluid filter
EP0923972A1 *Dec 17, 1998Jun 23, 1999Societe Nationale D'etude Et De Construction De Moteurs D'aviation, "S.N.E.C.M.A."Selfwashable device for separating and filtering solid particles in a liquid flow and use in a fuel injection system provided with such a device
EP1122358A2 *Jan 25, 2001Aug 8, 2001Andritz AGSorter for cleaning a fibre suspension
EP1124003A2 *Jan 29, 2001Aug 16, 2001Andritz AGScreen for purification of fibrous pulp
Classifications
U.S. Classification210/304, 210/413
International ClassificationB01D29/11, D21D5/02
Cooperative ClassificationB01D2201/287, D21D5/026, B01D29/115
European ClassificationB01D29/11D2, D21D5/02B2