Centrifugal apparatus

Application filed. February 15, 1928, Serial No.

My invention relates to centrifugal apparatus and more particularly to apparatus for the continuous treatment of liquids containing suspended matter, including pulps, 5, colloids and the like. Centrifugal apparatus of various types have already been proposed for the treatment of such liquids, for instance apparatus having perforated or solid cylindrical, tapering or lenticular 10. bowls. In these apparatus various means are provided for separating the solids from the wall of the bowls, for instance, scrapers, means for displacing the bowls or part of their walls, or slides and valves of other 15 kinds at the periphery of the bowls. However, for solids which are particularly finely subdivided, only unperforated bowls can be employed. A particularly difficult problem is the centrifuging of pulps having sus20 pended therein very finely subdivided solids of exceptional density, as such solids stick very firmly to the walls of the bowl and are difficult to remove by scrapers. The solution of the problem by displacing part of a taper25 ing or lenticular bowl in order to eject the solids is not satisfactory on account of the excessive thrust exerted on the parts controlling the displacing mechanism which may become prohibitive in machines of larger 30 size. Discharging the solids by several slides or valves at the periphery is primitive and unreliable, apart from the fact that hard and sharp solids cause considerable wear of these parts which interferes with the oper35 ation of the apparatus.

It is an object of my invention to provide a centrifugal apparatus which is suitable for the treatment of any liquids containing suspended solids, but is particularly designed ⁴⁰ for liquids containing dense and very fine solids. To this end I provide a bowl having unperforated walls, a peripheral annular discharge slot of invariable width and an annular valve which is adapted to close the ⁴⁵ slot so that the separated solids act as the packing.

In a preferred embodiment of my invention I so design the annular valve that the solids are collected between the valve and ⁵⁰ the edges of the bowl.

APPARATUS

254,448, and in Germany February 22, 1927.

Advantageously the bowl is of lenticular cross-section and constituted by two sections defining between them a peripheral slot of invariable width, and the annular valve or slide is so designed that the centrifugal ac- gg tion will exert on it a component tending to open the valve in order to facilitate the opening thereof.

I may arrange a plurality of bowls on a common shaft which are operated simultane- eo ously or preferably alternately, by duplicating the annular valve and controlling a pair of bowls alternately by the two valves.

The liquid to be treated may be introduced by means of a stationary tube arranged co- β5 axially within the hollow driving shaft of the apparatus.

In the drawing affixed to this specification and forming part thereof a pair of centrifugal bowls embodying my invention are illus-. 70 trated diagrammatically by way of example in axial section.

Referring now to the drawing, a is a hollow shaft, δ and c are centrifugal bowls keyed on the shaft each comprising an upper sec- 75 tion d and e' and a lower section e and d', respectively, the two sections of each bowl defining between them a substantially lenticular annular chamber. Peripheral discharge slots f and respectively, are con- 80 stituted by parallel faces or edges m and u on the parts d and e and i' and v on the parts e' and d', respectively.

In the parts d and e constituting the upper bowl δ, a beveled face s is formed adjacent 85 the parallel face m of the upper part d and a peripheral rib w extends downwardly from the beveled part so as to form an annular peripheral recess h on the part d. Outwardly extending flanges i and ® are formed adj a- 80 cent the parallel edges u and i' of the parts e and e', respectively, the flange i extending downwardly and the flange x extending upwardly from the parallel faces u and i', respectively. h' is a peripheral recession the 05 lower part d' of the bowl c which is constituted by an upwardly extending rib iio' and a short beveled face adjacent to parallel edge v.

Means are provided for varying the area 1*»«

1,816,40» through which the goods from the bowls δ, c are discharged after having passed the slots /, /' and such means comprise an axially displaceable slide g which is splined ⁵ on the shaft between the bowls δ, c so as to partake in the rotation of the shaft but free to be displaced in parallel to its axis as indicated by the arrows, g' and g are cups formed at the upper and lower arms of the ¹⁰ slide g and constitute a duplicate valve for the bowls. The upper cup g' is equipped with a peripheral flange y extending into the recess h of the part d, z is a beveled face extending downwardly from the flange and ¹⁵ z' is a recess formed below the beveled face for the reception of the flange i on the part e. The lower cup g is formed with a downwardly projecting flange y', mating with the recess h', a beveled face z and a recess ²⁰ z' mating with the upwardly projecting flange x.

The beveled faces z and z are provided on the valves or cups for the purpose specified, to wit, generating an axial component ²⁵ of the centrifugal force for facilitating the lifting of the valves.

k and k' are discharge passages at the upper end of the bowls δ and c, respectively, t is a stationary tube inserted coaxially and ³⁰ with some clearance within the hollow shaft a, j is a central partition in the tube t by which it is subdivided into two semi-circular areas, I is an inclined deflector arranged at the level of the central plane of the upper ³⁵ bowl δ at one side of the central partition. Λ the wall of the tube t being partly cut away at o above the deflector, and n is an annulus inserted in the hollow shaft a and surrounding the tube t. The annulus n com⁴⁰ prises two faces flaring toward the tube t from either side of perforations p in the hollow shaft a. q is a recess formed in the bosses of the parts d, e adjacent the perforations p, and r, τ’ are pipes extending down⁴⁵ wardly into the part e from the recess q. Similar means indicated by the Same letters but indexed I' etc., are provided for the lower part d' of the lower bowl c.

In operation, and assuming, that the slide ⁰ g has been moved upwards so as to close the upper bowl δ by its cup or valve g', the shaft a is rotated at high speed by any suitable means, hot shown, liquid being supplied to the bowls b, c, and any other bowls on the same ⁵ shaft. The relative axial displacement of the flanges y and i and the flanges y' and x with respect to their recesses is so determined as to provide a certain clearance onto prevent direct engagement of the parts, the solids in ⁸⁰ the liquid'serving as the packing. This packing action occurs immediately upon the bowls being charged with liquid or upon their beginning to rotate, and is absolutely reliable. When the closed bqwls are rotating and are continuously supplied with liquid the body of accumulated solids builds up gradually higher and higher on the bottom of the parts e and d', and the liquid is gradually dis- . pelled toward the upper and central regions of the bowls on account of its lower density, 70 and finally is discharged at k, k'.

Practically, the liquid has been completely separated from the solids when the body of solids has approximately risen to the level of the discharge passages k, k'. At this mo- 75 ment, the slide g is reversed so that its cup or valve g closes the lower bowl c and its cup or valve g’ opens the upper bowl δ, laying open its slot / so that the solids are completely ejected and the bowl is ready for a fresh 80 charge when, in turn, the lower bowl c has completed its operation, and the slide g is again reversed.

Although it is possible to get a packing between the recesses Δ and A', respectively, of 85 the bowls and the flanges y and y', respectively, by the solids of the liquids alone, it may be desirable to have an additional packing. And I prefer to provide for this purpose certain packing means inserted into the ⁰⁰recesses A and A', respectively, as.indicated in the drawing by h.

Any suitable means (not shown) can be provided for automatically regulating the flow of liquids in time with the reversing of ⁰⁵the slide g so that liquid is only supplied to that bowl or to those bowls which has, or have, been closed by the valve or valves g' and g.

It is to be understood that I am not limited to the construction shown and described by 1°° way of example. For instance I do not desire to be limited to any definite configuration of the bowl or bowls, of their annular slots / or /' and the slide g, an important feature of my invention being that the slide g is ¹⁰⁵adapted to close the bowl or bowls and to pack the clearance between the recesses and the flanges cooperating therewith, by the separated solids.

I wish it to be understood that I do not ¹¹⁰desire to be limited to the exact details of construction shown and described for obvious modifications will occur to a person skilled in the art.