US 3279687 A
Description (OCR text may contain errors)
C. L. AMERO Oct. 18, 1966 CENTRIFUGE 5 Sheets-Sheet 1 Filed May 8, 1964 C. L. AMERO Oct. 18, 1966 CENTRIFUGE 5 Sheets-Sheet 2 Filed May 8, 1964 United States Patent 3,279,687 CENTRIFUGE Clifford L. Amero, East Walpole, Mass, assignor to Bird Machine Company, South Walpole, Massz, a corporation of Massachusetts Filed May 8, 1964, Ser. No. 366,121 Claims. (Cl. 233-7) This application is a continuation-in-part of abandoned United States Serial No. 283,054, filed May 24, 1963.
This invention relates to a solid bowl centrifugal separator for separating liquid from finely divided solids and a method of operating such a separator while the level of liquid retained in the bowl is above the opening at the solids discharge end of the bowl. More specifically, the invention comprises such a separator in which means are provided to vary the depth of retained liquid while the separator is in operation.
It has been discovered that in a separator having continuous solids discharge accompanied by a minimum of liquid for a given centrifugal force level, better processing results occur when the level of retained liquid is adjusted to provide hydraulic assistance to the movement of the solids within and from the machine. However, this requires a retained liquid level deeper than that which can.
normally be employed when the separator begins running since, until solids are conveying from the machine, a retained liquid pool above the solids discharge opening would result in the discharge of liquid through that opening.
It is thus an object of the invention to provide a centrifugal separator in which the depth of retained liquid can be adjusted while the separator is running to a level above that of the opening at the solids discharge end of the bowl.
Another object is to provide a centrifugal separator in which the depth of retained liquid can be adjusted while the separator is running, and in which, once a depth adjustment has been accomplished, the new liquid level will be stable despite slight variations in feed rate.
Another object is to provide a separator of the type described in which a liquid discharge conduit is provided, located to remove liquid at a point within the travel of the solids conveyer and movable radially of the bowl to vary the depth of liquid retained within the bowl.
Another object is to provide a separator of the type described in which the bowl is rotatable with respect to the liquid discharge conduit, the latter extending outwardly from adjacent the center of the bowl and terminating in a scoop opening opposed to the direction of rotation of the bowl.
A further object is to provide a separator of the type described having a plurality of liquid discharge conduits, each of which is radially adjustable to vary the position of its scoop opening with respect to the bowl.
A further object is to provide a centrifugal separator in which an artificial filling layer is employed on the inner face of the bowl to allow the depth of retained liquid to be above that of the opening at the solids discharge end of the bowl, and in which a no-clearance ring is provided adjacent the end of the conveyer to protect the artificial filling layer from being washed away by the liquid.
A further object is to provide a centrifugal separator having a rotatable conveyer in which at least one liquid discharge conduit extends radially outward from the center of the bowl and removes liquid at a point within the axial extent of the conveyer, even though the retained liquid layer does not extend radially inwardly of the conveyer hub.
An additional object is to provide a centrifugal separator in which wash water is introduced and removed separately from the liquid of the feed mixture.
Other and further objects willbe. apparent from the drawings and from the description which follows.
In the drawings:
FIG. 1 is aview in vertical section partly broken away showing one embodiment of the present invention;
FIG. 2 is a view in cross-section taken along line 2-2- of FIG. 1;
FIG. 3 is a view in cross-section taken along line 3-3 of FIG. 1;
FIG. 4 is a view in cross-section taken along line 44.
of FIG. 1;
FIG. 5 is a view in section taken along line 55 of FIG. 4;
FIG. 6 is a view in vertical section of a portion of another embodiment of the invention.
As shown in FIG. 1 of the drawing, one embodiment of the invention comprises a generally cylindrical housing 10 having at one end a solids discharge chamber. 12-located betweenthe wall.14 and annular internal bafile16.
An outlet 18 is provided for removing accumulated solid.
material from the bottom of chamber 12. Mounted for rotation within the housing 10 is a generally cylindrical bowl 20 supported at its left-hand end as seen in FIG. 1 by a spider 21 and sleeve shaft 22 journaled in a suitable bearing 23. Bowl 20 is provided at its left-hand end with an annular extension or gutter 24 into which feed pipe 25 extends through end wall 26 of housing 10. Feed pipe 25 terminates in an outlet portion 29 extending tangentially in the directionv of rotation of bowl 20. Bowl 20 terminates at its right-hand endas seen in FIG. 1 in a slightly conical end portion 28 which opens into solids discharge chamber 12, being supported at its right-hand end by a spider 30 and sleeve shaft 32 journaled in bearing 34 .and having belt drive sheave 36 keyed to its end.
Mounted coaxially within bowl 20 is a helical conveyer 38 which includes a hollow cylindrical drive shaft 40. secured at its left-hand end to drive shaft 42 journaled in sleeve shaft 22 and supported at its right-hand end on sleeve shaft 44 journaled in sleeve shaft 32. Shafts 22 and 42 are interconnected by any suitable gearing (not shown) to rotate at slightly different speeds, e.g., 650 rpm. for the bowl and 630 rpm. for the conveyor in a manner well known to those skilled in the art, both being driven from any suitable power source through sheave 36.
Adjacent the intersection of bowl 20 and conical end portion 28 hollow shaft 40 is provided with a radially outwardly extending generally annular chamber 46 which interrupts all but the peripheral portion of the flights of conveyer 33 and serves as a housing for liquid discharge conduits 48, 50 which extend radially outwardly from adjacent the center of hollow shaft 40 through an opening in the wall thereof. Annular chamber 46 is divided into two portions by a radially inwardly extending annular flange 52 interposed between conduits 48 and 50. Apertures 54, 56 through the wall of chamber 46 provide communication between the interior of bowl 20 and the respective parts of chamber 46.
As best appears in FIG. 3, each of the conduits 48, 50 terminates at its outer end in a scoop 78, 80, each of which has an opening or mouth opposed to the direction of rotation of bowl 20.
In operation of the device, the feed mixture of liquid and solid particles is introduced through inlet pipe 25 whence it passes into bowl extension or gutter 24 being introduced in the same direction as the direction of rotation of the bowl 20. The mixture then passes through the apertures 27 in spider 21 and along the inner face or wall of spinning bowl 20. Under the influence of centrifugal force the feed forms a layer against the inner wall of the bowl, the solid particles being urged by reason of their high specific gravity to form a layer immediately next to the face of the bowl while the lighter liquid tends to rise toward the center of the bowl. When two different liquids are present, the lighter of the two will form a separate layer closer to the center than the other liquid, while the latter, being lighter than the solids, will form a layer between the first liquid layer and the solids layer. The radial thickness of these various layers remains constant so long as the radial positions of the mouths of conduits 48, 50 remain constant and so long as each has sufficient capacity to remove liquid at the rate it is introduced.
The finely divided solids are urged to the right as seen in FIG. 1, along the inner face of bowl 20 by relative rotation of the bowl and the screw conveyer 38. Some of the liquid is removed by conduits 48, 50, and as the remaining mixture of liquid and of solid particles flows beyond annular chamber 46, the solid particles continue to be urged along the sloping face of conical portion 28 of the bowl. Normally, solids will accumulate along portion 28 to form a layer or beach between portion 28 and the outer edges of the conveyer blade. The liquid is prevented by centrifugal force from advancing beyond a point on the conical portion 28 determined by the position of the mouth of conduit 50. Consequently, the solid particles emerge from the liquid at some point, continue across the remainder of portion 28 and are removed at outlet 18.
Considering more particularly the action of conduit 48, the rate at which liquid is discharged varies with the degree to which the mouth of the conduit is submerged in the liquid. For a given feed rate, the level of retained liquid will automatically adjust itself until the discharge just balances the feed. The conduit is sized so that under normal conditions of operation, the mouth will be partially submerged. In this manner, a stable liquid level is provided, despite variations in the feed rate, for should the feed rate increase or decrease, the resulting tendency of the pool to rise or fall will automatically change the amount of the conduit mouth that is submerged and thereby change the liquid discharge rate to recreate the feeddischarge equilibrium.
When the separator is firstset in operation, the retained pool level must necessarily be kept below the right-hand opening of the bowl, to prevent liquid discharge at the solids discharge end of the bowl. Once solids are discharging, however, it has been discovered that solids discharge is substantially improved if the pool level is raised above the bowl opening (FIG. 6), thereby providing buoyant force to aid the solids in their entire travel across the beach. The beach solids act to prevent the escape of liquid from the bowl at the solids discharge end. In order to operate with a high pool it is thus important to be able to change the depth of retained liquid while the separator is running. To this end, means are provided for the radial adjustment of the conduits 48, 50 above and below the level of the right hand opening of the bowl.
A cup 58 mounted adjacent the center of rotatable hollow shaft or hub 40 and secured thereto serves as a support for the outer race of bearings 60, 61, the inner races of which support for rotation a. fitting 62 carrying at its right-hand end an eccentric 64. Fitting 62 is fixed against rotation by means of a rod 66, one end of which is keyed to fitting 62 and the other end of which extends outwardly beyond the end of housing 10 and is secured in any suitable manner (not shown) externally. of the machine. Rotatably mounted upon eccentric 64 is a hollow fitting 68 which carries and communicates with liquid discharge conduit 48. Fitting 68 in turn carries an eccentric 70 at one end and is secured to hollow shaft 72 through the center of which rod 66 extends. Rotatably mounted on eccentric 70 is another fitting 74 having a hollow interior which is in communication with liquid diswhich an adjustment bolt 94 passes, the stud being engaged 1 between the head 95 of the bolt and a collar 96 secured to. its shank, while the other threaded end of the bolt is en-, gaged in a tapped hole in stud 96 secured to retaining ring 88.
As a result of the foregoing construction, the pipes 72 and 76 may be rotated one with respect to the other along their axes by taking up :or backing off on bolt 95 and are held fixed in any desired position by the bolt. This relative rotation varies the position of fitting 74 on eccentric 70, causing the mouth of conduit 50 to move radially inwardly or outwardly with respect to the axis of bowl 20.
Collar 84 is bolted to ring gear 100 which clamps an extension pipe 102 in place by means of flange 103 to form an extension of pipe 76. Worm 104 is mounted on pedestal 106 by means of brackets 108, 110 in-position to mate with ring gear 100 and is provided with crank arm 112..
Manual rotation of crank arm 112 rotates ring gear 100 I with respect to fixed pedestal 106 carrying with it both pipe 72 and pipe 76 (which is rotatively fixed with respect to 72 by bolt 94) and associated fittings 68, 74. The rotation of fitting 68 on fixed eccentric 64 causes the mouth of conduit 48 to move radially inwardly or out-. wardly with respect to the axis of bowl 20. Since fitting 74 does not rotate with respect to eccentric 70 upon rotation of ring gear 100, the positions of the mouths of conduits 48 and 50 with respect to each other do not change when ring gear 100 is rotated as described above and both conduits move radially inwardly and outwardly together. Flange or batfie 52 maintains separation of the two liquids and prevents their remixing as they enter the. mouths of conduits 48, 50.. Rotation of conveyer .38
with respect to bowl 20 serves to urge the solid material along the inner wall of the bowl from left to right as seen in FIG. 1. The position of the mouth of conduit 50 is adjusted radially by rotating the conduit ahoutec- V centric 70 by actuating bolt 94 to maintain the interface between the two liquids at the desired level at the lefthand side of chamber 46 as seen in FIG. 1. Under these conditions chamber 46 acts as a radial bafile to prevent any of the lighter liquid from passing beyond it ,to reach conduit 50. It i the annular chamber 46 which. allows the discharge conduits to be located to remove liquid at a point within the travel of the, solids conveyer without having to increase the entire conveyer hub diameter to the point where liquid from the retained pool enters hub 40. The position of the mouth of conduit 48 is adjusted radially by rotating the conduit about eccentric 64 by means of crank arm 112 so as to place the mouth radially inwardly of the position of the interface,.so that it will remove only lighter liquid.
When the radial position of a conduit mouth is adjusted to change the pool level, the rate of liquid discharge is temporarily shifted out of equilibrium with the feed rate. Importantly, however, as the pool level adjusts the equilibrium is automatically restored and the new pool level is a stable one. The apparatus thu has the ability to operate over a range of stable pool depths and to shift from one to another while in operation.
Although the adjustable scoop mechanism described is the preferred embodiment of the invention, other means for achieving the stable high pool operation of the invention are possible. For example, in a separator in which liquid discharge occurs at one end of the bowl through an annular weir, adjustments of the weir opento bowl wall clearance.
5, ing will change the pool depth. Other variations and embodiments will occur to those skilled in the art. Of course, the adjustable scoops can easily be incorporated into a separator in which the flows of solids and liquid oppose each other instead of being concurrent as shown herein.
Some feed mixtures do not contain solids of the type that will form anunmovable layer between blade tip and bowl wall. In such a case, this layer must be built up artificially of a substance such as gypsum or plaster of Paris, before the pool level can be raised. Artificial layers as such are well known in the art for'filling blade tip In the practice of the high pool method of the invention with an artificial filling layer, the end of the layer becomes eroded by the liquid and washes away. To overcome this problem, met-a1 ring 150is provided (FIG. 6) on the inner surface of the bowl adjacent the solids discharge end. Ring 150 is machinedto have zero clearance from the conveyer 38, and protects the artificial layer 151 from the hydraulic head of the high pool. While the ring 150 as shown is of the order of inch wide, the principle of a no-clearance fit between the conveyer and the bowl at the point of solids discharge can be applied-using a ring of any dimension axially.
Wash inlet pipe 77 envelopes both pipes 72 and 76, being fixed to the outside of pipe 76 and having a lateral outlet 79 near itsinner end'to permit wash liquid to be introduced into the interior of shaft 40 whence it flows through nozzles 83, onto the solids which are being advanced along conical portion 28; The outer end of wash inlet pipe is connected to a flexible hose 85 through which a supply of water or other liquid may be introduced for washing the solids before they are discharged. Baflle 81 secured to the interior of shaft 40 preventsthe wash liquid from flowing directly into annular chamber 46 The double conduit arrangement makes it possible to separate two liquids of differing densities from each other as well as from a finely divided solid. It will be understood that additional conduits may be provided to remove additional layers of liquid if desired. When wash water is introduced through inlet 77, it may be removed through conduit 50 along with the second liquid, if there is one.
The foregoing construction is particularly useful in separating from solids those liquids which tend to foam, because back pressure can be applied to conduits 48, 50 to repress foaming without preventing flow of the liquid discharge therethrough under the head of pressure built up by the rotating mass of liquid entering the mouths of the scoops.
Although specific embodiments of the invention have been described herein, it is not intended to limit the invention solely thereto, but to include all of the obvious variations and modifications within the spirit andv scope of the appended claims.
What is claimed is:
1. A centrifugal separator comprising a rotatable bowl for receiving a mixture of liquid and finely divided solid particles,
a solids discharge chamber adjacent one end of the bowl in communication with the interior thereof through a solids discharge opening,
inlet means for introducing said mixture into said bowl,
a rotatable conveyer mounted within the bowl coaxially therewith,
means for rotating the bowl and conveyer at different speeds to cause the solid particles to move along the inner face of the bowl to the solids discharge chamber, while a layer of liquid is retained in the bowl radially adjacent and in contact with the moving solids, said bowl having an internally unobstructed tapered portion with its smallest diameter adjacent said solids discharge opening, said bowl thereby being adapted to retain said liquid layer in cont-act with the moving solids at levels ranging from below toabove the solids discharge opening at the point of solid discharge, and means operable while the separator is running for adjusting the level of said liquid layer through levels ranging from below to above said solids discharge opening at'the point of solids discharge for providing an hydraulic assist to the solid particles crossing said point, and for. removing liquid from the bowl at a ratewhich will automatically fluctuate in direct correspondence with anyfluctuations in the rate of feed of liquid into the bowl, thereby maintaining said liquid at a stable and substantially constant level. 2. A centrifugal separator as claimed in claim 1 wherein said'last mentioned means include at least one liquid discharge conduit extending outwardly from adjacent the axis of the bowl, and adapted to remove liquid at a point within the axial extent of said conveyer, said bowl being rotatable with respect to said conduit, and said conduit terminating at its outer end in a scoop opening opposed to the direction of rotation of the bowl, and means operable while the separator is running for adjusting the position of said scoop opening toward and away from the wall of the bowl to vary said predetermined level of liquid through a range of levels below and above said solids discharge'o'penin'g at the point of solids discharge.
3. A centrifugal separator as claimed in claim 2 including a plurality ofsaid liquid discharge conduits and means for adjusting the position of each scoop opening toward and away from the wall of the bowl.
4. A centrifugal separator as claimed in claim 2 in which said conveyer comprises a hollow shaft carrying a helical blade, said liquid discharge conduit extends outwardly from the interior of said shaft, and an annular enlargement of said shaft is provided embracing said conduit, said enlargement having at least one aperture adjacent its periphery to permit said liquid to flow into the scoop opening of said conduit, said enlargement thereby enabling liquid to be removed at a point within the travel of said helical blade while the retained liquid may be spaced from the unenlarged portions of said shaft.
5'. A centrifugal separator as defined in claim 4 in which a plurality of said liquid discharge conduits is provided and a transverse baflle extends between adjacent conduits to keep separate the liquids flowing into the two conduits and to prevent turbulence within said liquid caused by the first said scoop opening from affecting the flow into the second scoop opening.
6. The separator of claim 1 wherein said conveyer has a helical blade and means for preventing liquid discharge at the solids end when the level of retained liquid is raised above said solids discharge opening at the point of solids discharge comprising a metal ring on the inner face of the bowl at the point of solids discharge, and a false filling layer on the inner face of the bowl adjacent said ring, the inner surface of said ring having zero clearance from at least a portion of said blade.
7. A centrifugal separator comprising a rotatable bowl for receiving a mixture of liquid and finely divided solid particles,
a solids discharge chamber adjacent one end of the bowl in communication with the interior thereof,
inlet means for introducing said mixture into said bowl, a rotatable helical blade conveyer mounted within the bowl coaxially therewith,
means for rotating the bowl and conveyer at different speeds to cause the solid particles to move along the inner face of the bowl to the solids discharge chamher,
a metal ring on the inner face of the bowl at the point of solid discharge,
and a false filling layer on the inner face of the bowl adjacent said ring, the inner surface of said ring having zero clearance from at least a portion of said blade.
7 v 8 8. The method of separating a mixture of liquid and said solids discharge opening, said bowl thereby finely divided solids comprising the steps of being adapted to retain a layer of liquid at a level feeding said mixture into the bowl of a centrifugal below the level of solids at the point of solids disseparator of the type in which the solids are urged charge, and by a rotatable conveyer axially along the inner surmeans for maintaining said retained liquid at a preface of the bowl and radially approach the axis of determined level including at least one liquid dis-- the bowl as they cross a beach to enter a solids discharge conduit extending outwardly from adjacent charge chamber through a solids discharge opening, the center of the bowl and having its liquid removal, and in which a layer of liquid is retained radially opening substantially within the axial extent of said adjacent and in contact with said moving solids, 10 conveyer, said bowl being rotatable with respect to increasing the level of said retained liquid layer from said conduit, and said conduit terminating atits outer an initial operating level below said solids discharge end in a scoop opening opposed to the direction of opening at the point of solids discharge to a new rotation of the bowl. I operating level above said opening at the point of It). The separator of claim 9 wherein said conveyer solids discharge, thereby providing an hydraulic aS- includes a hollow shaft and said separator further com-, sist to the solid particles crossing said point, prises means enabling said conduit to remove liquidvat and removing liquid from the bowl at a rate which a point within the axial extent of the conveyer even will antomatically fluctuate in direct correspondence though the layer of retained liquid does not extend radiwith any fluctuations in the rate of feed of liquid ally inwardly of said hollow shaft into the bowl, thereby maintaining said liquid at a stable and substantially constant level. R f r nces Cited by the Examiner 9. A centrifugal separator comprising a rotatable bowl UNITED STATES PATENTS gz r i g a mlxture of q and fi y dlvlded solld 1,572,299 2/1926 McEntire 233;. a solids discharge chamber adjacent one end of the 2111508 3/1938 Jones 233*22 bowl in communication with the interior thereof, 2685369 8/1954 Crossley 233-14 inlet means for introducing said mixture into said bowl, 3050238 8/1962 Doyle et j a rotatable conveyer mounted within the bowl coaxially 3'096'282 7/1963 Trotter 233 7' theregvith, t t, th b 1 d t (m t FOREIGN PATENTS means or ro a mg e ow an conveyer a l eren 3() speeds to cause the solid particles to move along the 2:23:53
inner face of the bowl to the solids discharge chamber, while a layer of liquid is retained in the bowl radially adjacent and in contact with the moving solids, said bowl having an internally unobstructed 3 CARY NELSON P'lmary Exfzmmer' tapered portion with its smallest diameter adjacent HENRY KLINKSIEK, Exammer- 1,021,297 12/1957 Germany.