US3494472A - Sieve centrifuge - Google Patents

Description

Feb. 1o, 1970 @.P. QUETSCH 3,494,472

SIEVE CENTRIFUGE I Fi'led'June 1:5, 196einl- United States Patent() U.S. Cl. 210-374 4 Claims ABSTRACT F THE DISCLOSURE A sieve centrifuge, especially for separating finely divided solid material in suspension in a liquid from the latter, wherein the material to be centrifuged is fed into one end of a rotating lter drum so that during operation of the centrifuge the liquid will pass through openings in the cylindrical wall of the lter drum, while the solid material accumulating on the inner drum surface is continouusly transported, by semi-annular pusher elements xed to a coaxial shaft in the drum and inclined to the shaft axis, from one to the other end of the drum to be discharged at the other end, and wherein the drum and the shaft are rotated at different speeds. The angular position of the pusher element relative to each other is preferably adjustable and the rotational speed of the shaft is also preferably infinitely adjustable to thereby vary the time of passage of the solid material through the centrifuge.

Background of the invention The present invention relates to a sieve centrifuge with a cylindrical drum, especially for separating finely divided solid material in suspension in a liquid from the latter.

Various arrangements for such centrifuges are known in the art. In one known construction, the suspension to be separated is fed in axial direction into a sieve drum rotatable about a horizontal axis so that during operation of the centrifuge the liquid material will pass through the perforated or porous cylindrical wall of the drum while the solid material will accumulate on the inner surface thereof to be subsequently discharged from the interior of the material by doctor blades. A decisive disadvantage of this known arrangement is that this arrangement can work only intermittently, since during removal of the solid material the ltering operation has to be stopped. Another known centrifuge has a drum having an uninterrupted wall and the material to be centrifuged is continuously transported by a feed screw through the drum toward the discharge end of the latter, whereby the feed screw is rotated with a speed different from the peripheral speed of the drum. The drum of this construction has a conical end through which the separated solid material is discharged by a correspondingly tapered end of the feed screw, whereas the liquid material accumulating in the central part of the drum is withdrawn therefrom through a tube or the like. This centrifuge may be continuously operated, however, it has the disadvantage that the separation of solid and liquid material is insuicient, especially if it is desired to discharge the solid material substantially dry from the centrifuge.

Centrifuges of the last-mentioned type will provide for an optimum centrifuging action if the number and inclination of the convolutions of the feed screw and the relative speeds of drum and feed screw are exactly correlated to the consistency of the material to be centrifuged. However, if it is desired to separate different suspensions with an optimum efficiency, then it is necessary to use for each of the suspensions a different centri- 3,494,472 Patented Feb. 10, 1970 C'ce fuge of the aforementioned kind. This will be however possible only in exceptional cases, whereas small or medium size plants or laboratories will have only a single centrifuge and in this case they will have to accept a poor efficiency of separating the solid material from the liquid of the suspension, due to the fact that the centrifuge used is constructed to separate only the elements of a specific suspension with maximum eiciency.

It is an object of the present invention to overcome this disadvantage of centrifuges known in the art.

It is a further object of the present invention to provide for a sieve centrifuge in which the elements thereof are arranged and cooperate with each other in such a manner that the centrifuge can be operated with optimum efciency regardless of the type of material to be separated by the centrifuge.

It is an additional object of the present invention to provide for a centrifuge of the aforementioned kind which is constructed of relatively few and simple elements so that the centrifuge can be constructed at reasonable cost and will stand up properly under extended use.

Summary of the invention With these objects in view, the sieve centrifuge according to the present invention, which is especially adapted for separating finely divided solid material in suspension in a liquid from the latter, mainly comprises support means, a filter drum tuinably mounted on the support means, a shaft coaxial with the drum and turnably about the axis of the latter, a plurality of semi-annular pusher means lixedly mounted on the shaft for rotation therewith and extending inclined to the shaft axis toward the inner surface of the drum to be spa-ced by a small clearance from the inner surface, and drive means operatively connected to the drum and to the shaft for rotating the drum and the shaft respectively with different speeds.

In a preferred form of the sieve centrifuge according to the present invention, the various pusher means are angularly adjustable mounted on the shaft so that the relative position of the semi-annular pusher means to eachother may be adjusted. It is also preferred to drive the centrifuge drum and the shaft to which the pusher elements are connected by a single drive motor through a pair of transmission means and to construct one of the transmission means, preferably the transmission means connected to the shaft, to be innitely variable.

The novel features which are considered as characteristic for the invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawing.

Brief description of the drawing FIG. 1 is an axial cross-section through the sieve centrifuge according to the present invention; and

FIG. 2 is a perspective view of one of the pusher elements which are mounted on the shaft.

Description of the preferred embodiments Referring now to the drawings and especially to FIG. 1 of the same, it will be seen that the sieve centrifuge according to the present invention comprises a substantially cylindrical sieve drum 1 mounted for rotation about a substantially horizontal axis on a pair of antifriction bearings 2 and 3 which in turn are mounted on a stationary machine frame, schematically indicated in FIG. l. The sieve drum 1 has an outer cylindrical wall provided with closely spaced openings 9 therethrough and an inner cylindrical filter element 10 abutting against the inner surface of the outer wall. A pair of end walls close the cylindrical portion of the drum at opposite ends thereof, and the left end wall, as viewed in FIG. 1, is preferably of frustoconical shape and the aforementioned bearings 2 and 3 are mounted on tubular projections projecting outwardly from the respective end walls. A pulley 4 is fixedly connected to the right tubular projection, as viewed in FIG. l, so that the sieve drum may be rotated about its axis. Coaxially arranged within the drum 1 is a shaft 5 projecting with its right end beyond the tubular extension at the right end wall of the drum. The shaft 5 is mounted for rotation about its axis on a pair of antifriction bearings, for instance ball bearings 6 and 7 which are in turn mounted in the aforementioned tubular extensions of the drum. A plurality of pusher means, as best shown in FIG. 2, are mounted adjacent to each other on the shaft 5 and each of the pusher means comprises a sleeve 11 extending about the shaft and a semi-annular plate element fixed to the sleeve and extending inclined to the axis of the latter toward the inner surface of the drum to be spaced at its peripheral edge with a very small clearance from the inner face of the cylindrical filter element 10. Each of the sleeves 11 and therewith the semiannular element 13 fixed thereto, for instance by being welded at the inner periphery to the outer sleeve surface, is angularly adjustable relative to the other pusher elements about the axis of the shaft 5 and can be fixed in any adjusted position to the shaft for rotation therewith by a set screw 12 screwed into a correspondingly threaded bore in the sleeve and engaging the shaft. The material to be centrifuged is fed into the interior of the drum 1 through inlet means 14 in a form of a conduit having an end coaxially arranged with the shaft axis and extending into the chamber 15 of distributor means 18 coaxially arranged with the shaft axis in the frustoconical portion of the left end wall of the drum, as view in FIG. l. A plurality of passages 17 lead from the chamber 15 inclined to the shaft axis outwardly so as to guide the material passing through the inlet means 14 into the interior of the drum toward the inner surface of the cylindrical drum portion. The right end wall, as viewed in FIG. 1, is provided with a plurality of outlet openings 19 communicating with the interior of the drum 1 in the region of the inner surface of the cylindrical filter member 10. A pulley 8 is mounted on the righ end, as viewed in FIG. 1, of the shaft 5 and this pulley is constructed in a known manner to infinitely vary the rotational speed of the shaft 5, even if the latter is driven from a motor of constant speed. As shown in FIG. l, the pulley 8 comprises two sheaves having conical surfaces facing each other and one of the sheaves, for instance the right sheave as viewed in FIG. 1, may be axially adjustable with respect to the other by being for instance threadingly connected to a coaxial sleeve integral with the other sheave so that a V-belt located between the conical surfaces of the two sheaves will engage the latter at distances from the shaft axis depending upon the axial adjustment of the sheaves with respect to each other whereby the rotational speed of the shaft may be adjusted in an infinite manner.

The operation of the centrifuge will be obvious from the above description. The material to be separated is fed into the sieve centrifuge through the inlet passage 14 and distributed by the distributor means 18 toward the inier surface of the sieve drum. The liquid will pass through the inner filter element 10 and through the openings 9 of the outer wall of the sieve drum 1 whereas the solid material accumulating on the inner surface of the filter element 10 will be continuously pushed by the rotating pusher elements 13 towards the outlet opening 19 to be discharged therefrom.

The sieve centrifuge according to the present invention has the advantage that by means of the infinitely variable difference between the rotational speed of the shaft 5 and the sieve drum an optimum residence time of the solid material in the drum can be obtained. In addition, it is also possible by angularly adjusting the position of the pusher elements with respect to each other t0 determine the optimum residence time of the solid material at predetermined portions of the sieve drum. This makes it possible to obtain a residence time which is exactly suitable for the respective characteristic of the material to be centrifuged. The arrangement according to the present invention permits also to establish in selective regions of the sieve drum rest periods for the material to be separated during which an especially intensive draining of liquid from the solid material will take place. This feature is especially important during separating very finely divided or delicate solid material in suspension in a liquid from the latter.

It will be understood that each of the elements describd above, or two or more together, may also find a useful application in other types of sieve centrifuges differing from the types described above.

While the invention has been illustrated and described as embodied in a sieve centrifuge with continuous discharge of the solid material separated in the centrifuge from the liquid in which it is suspended, it is not intended to be limited to the details shown, since various modification and structural changes may be made without departing in any way from the spirit of the present invention.

What is claimed as new and desired to be protected by Letters Patent is set forth in the appended claims:

1. A sieve centrifuge, especially for separating finely divided solid material in suspension in a liquid from the latter comprising, in combination, support means; a filter drum turnably mounted on said support means; a shaft coaxial with said filter drum and turnably about the axis of the latter; a plurality of semiannular pusher means arranged spaced from each other aboutsaid shaft and extendingrinclined to the axis of the latter toward the inner surface of said drum to be spaced by a small clearance from said inner surface; means mounting each of said semi-annular pusher means on said shaft angularly adjustable about the shaft axis and fxable in any adjusted position for rotation therewith; and drive means operatively connected to said drum and to said shaft for rotating said drum and said shaft, respectively, at different speeds.

2. A sieve centrifuge, especially for separating finely divided solid material in suspension in a liquid from the latter comprising, in combination, support means; a filter drum turnably mounted on said support means; a shaft coaxial with said drum and turnable about the axis of the latter; a plurality of pusher means mounted on said shaft for rotation therewith and each including a sleeve mounted on said shaft angularly adjustable about the axis of the later, a semi-annular piate element fixed to and extending inclined -to the axis 0f said sleeve towards the inner surface of said drum to be spaced a small clearance from the inner surface, and means to fix the sleeve in any adjusted position to the shaft for rotation therewith; and drive means yoperatively connected to said drum and to said shaft for rotating said drum and said shaft, respectively, at different speeds.

3. A sieve centrifuge, especially for separating finely divided solid material in suspension in a liquid from the latter comprising, in combination, support means; a filter drum turnablyA mounted on said support means and comprising an outer cylindrical drum member formed with a plurality of openings in the wall thereof, an inner cylindrical filter member abutting against the inner surface of said outer member, a pair of end walls each having a substantially cylindrical tubular outwardly projecting extension, one of said end walls being substantially conical, inlet means extending substantially coaxially through the extension of said one end wall, and outlet means in the other end wall in the region of the inner surface of said inner filter member; a shaft coaxial with said drum and'turnable about the axis of the latter; a plurality of semiannular pusher means mounted on said shaft for rotation therewith and extending inclined to the shaft axis towards the inner surface of said filter member to be spaced a small clearance from said inner .surface of said filter member; distributor means located in said conical end Wall coaxially xed to said shaft and communicating with said inlet means for guiding material coaxially introduced by said inlet means inclined at an acute angle to the shaft axis towards the inner surface of said filter member; and drive means operatively connected to saiddrum and to said shaft for rotating said drum and said shaft, respectively, at different speeds..

4. A sieve centrifuge, especially for separating nely divided solid material in suspension in a liquid from the latter comprising, in combination, support means; a filter drum comprising a pair of end walls each having a substantially cylindrical tubular outwardly projecting extension, inlet means extending substantially coaxially through the extension of `one of said end walls, and outlet means formed in the other end wall in the region of the inner surface of said lter drum; a pair of antifriction bearing means respectively surrounding said extension and turnably supporting said drum on said support means; a shaft coaxial with said drum and turnable about the axis of the References Cited UNITED STATES PATENTS 617,158 1/1899 Henderson 210-374 1,252,550 1/1918 Champney 74-230.17 1,655,426 1/ 1928 Laughlin 210-374 1,828,548 10/1931 Shapley 210-374 2,262,721 11/1941 Flygare et al. 74-230.17 X 2,462,098 2/ 1949 Hertrich 210-376 X 2,516,821 7/1950 Wright 74--230.17

JAMES L. DECESARE, Primary Examiner U.S. C1. X.R. 210-377

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