US2270173A - Centrifuge for separating solids from liquids - Google Patents

Description

H. SCHULZ Jan. 13, 1942.

Filed Jlily 19, 1959 H. SCHULZ GENTRIFUGEFOR SEPARATING SOLIDS FROM LIQUIDS Jan; 13, 1942.

Filed July 19, 1959 3 Sheets-Sheet 2 Jan. 13, 1942. vH.-SCHULZ 2,270,173

CENTRIFUGE FOR SEPARATING SOLIDS FROM LIQUIDS Filed Jul 19, 1939 a Sheets-Sheet 3 Film sAxwW aienteii .Fan. 1% T142 csn'rmrncr. FOR SEPARATING soLms mom moms Herbert Schulz, Berlin-Tempelliof, Germany Application July 19, 1939, Serial No. 285,426

. In Germany April 29, 1938 3 Claims.

This invention relates to centrifugesfor separating. the solid matter from mixtures of solids and liquids, such centrifuges being of the type in 7 ing-up in said mixture 9. high pressure in opposition to a lesser back pressure.

Another object of the invention is to make use of constricted fluid-mixture discharging orifices which assist the building-up under centrifugal force of the requisite excess pressure in the mixture by producing a difference in efiective level, or pressure head, between the surface of the admitted mixture and the surface of the-liquid ring into which said mixture is discharged.

Another object of the invention is to effect the requisite separation by impact of the high-speed fluid mixture against a rotary separation or deposition surface.

Another object of. the invention is to effect separation impact of the high-speed fluid mixture almost p rpendicularly to the rotary separation surface.

Yet another object of the invention is to provide a centrifuge comprising a rotatable separation drum arranged in a housing which also is rotatable but about an axis transverse to the axis of rotation of the drum.

Other objects of the invention will be apparent from the following specification and claims.

Examples embodying the invention will now be Fig. 7 is a section to a larger scale on the line VII-VII of Fig. 6.

Fig. 8 is a fragmentary sectional view showin an enlarged inlet discharge suitable for thickly fluid mixtures. Fig. 9 is a view similar to Fig. 3, but showing a modified form of centrifuge in longitudinal section, the centrifuge according to Fig. 9 having an arrangement of constricted spraying discharges separate from the inlet conduits.

Fig. 10 is a view similar to Fig. 6,- but showing the modification according to Fig. 9 to an enlarged scale.

The centrifuge according to Figs. 1 and 2 in-- cludes a centrifugal drum I rotatably mounted in bearings 2 and 3. The right-hand end wall of the drum I is closed, while th left-hand end wall has the form of a ring. The inlet for the mixture to be separated is a conduit is which is journalled in the bearing 2 in the manner of a trunnion. The inlet conduit l5 merges into radial outlets I6 which extend into the ring I! of liquid in the drum I at the inner peripheral surface I! of the liquid. The mixture, in consesurface of the greater depth of liquid in the outlets it, with their constricted discharges l8, and the surface I! of the liquid in the liquid ring confined by the drum. The resultant impact of the high speed streams with the separation surface of thedrum, in co-operation with the effect of centrifugal force, ensures a strong separation described with reference to the accompanying drawings, in which:

Figs. land 2 are sections at right angles to one another of a simple form of centrifuge.

Fig. 3 is a longitudinal section of a centrifuge comprising two drums having mutually transverse axes, Fig. 3 being a section on line III-III of Fi 5.

Fig. 4 is a section on the line IV-IV of Fig. 3. Fig. 5 is a section on the line V-V of Fig. 3. Fig. 6 is a detail sectional view to a. larger scale of a deposition pocket already shown in Fig. 4. riphery of the drum by deflecting plates 26 sur-y or deposition effect, whilst recoil of the solid matter is counteracted by the centrifugal force. The

impact of the high-speed discharge streams takes place almost perpendicularly tov the deposition surface presented by the internal periphery of the drum. While the solid matter is separated and deposited on the separation surface and is discharged from time to time by any known means, the excess of liquid flows over the inner circular edge of the left hand ring wall, as shown in Figure 1. v

Deflecting projections 25 throw the liquid streamback again towards the periphery, in

order to obtain as complete deposition as possible due to impact. The liquid streaming back is guided as far as possibie along the internal perounding the nozzles I8 so that any solids which may be entrained are given time for deposition.

Referring to Figs. 3 to 7, the centrifuge therein shown includes an outer housing constituted as a drum I which is rotatably supported by bearings 2 and 3 and which can be driven by a wheel or pulley 4. There extends through one of the journals of the drum I a shaft 5 which is connected through transmission gearing 6, I, 8, 9 and Ill to a second drum II. The drum II is arranged internally of the drum I with its axis perpendicular to the axis of the drum I, the drum II having a shaft I3 which is journalled in bearings I4 in the drum I. The drum II has a peripheral ring of teeth I2 which mesh with the last element II] of said gearing. The shaft 5 is held fast externally of the drum I. Thus, in the rotation of the drum I, the internal drum II is caused to rotate more or less slowly as determined by the transmission ratio of the gearing.

As shown in Figures 4 and 5 the drum II is formed in two similar halves, being arranged with an axial distance or space. Into this space extends the end piece or mouth of an inlet conduit I5 which is supported by the shaft I3 and the bearing 3 respectively. This inlet-conduit I5 for the mixtureto be separated extends into the middle of the inner drum II, the discharges I5 of said conduit being offset from the axis of the shaft I3 (see Fig. 3) and being provided at their outer ends with exchangeable nozzles l8 of constricted cross-section. Pockets or cells I9 are arranged at the internal periphery of the drum II and pivotal valve flaps 20 are adapted to close them. Pivotal props 2|, which are urged outwards under centrifugal force, serve to maintain the flaps in closed position during the deposition or separation stage. Pivotal pressers (not shown) serve to force the props away in order that the flaps 20 will adopt their open position during the discharge stage, at which stage the solid materials pass outwards through convergent funnels 23 into fixed receptacles (see Fi In view of the fact that the structure I5, I6 does not rotate with the inner drum II, the nozzles I8 do not enter the pockets I9, but simply extend closely thereto.

Due to the accumulation of pressure in the discharges I6 of the inlet conduit I5, the mixture is forced to pass at great speed through the nozzles I8 into the pockets I9. Fig. 3 illustrates the difference, or effective pressure head, between the surface of the pressure-accumulating liquid in the outlets I6 and the surface I! of the liquid ring in the drum I I. It is due to this difierence that the requisite discharge-stream speed through the nozzles I8 is obtained. The excess of liquids overflowing the annular inner edges of the halves of the drum II (see Fig. 4) and passing through the sieves 21 is expelled outwards by the centrifugal force through holes of the outer drum l into a fixed receiver surrounding thedrum I (see Figs. 3 and 5).

Fig. 6 illustrates a suitable flow of the stream into a pocket and shows how the stream flowing in the direction of the arrows impinges against several surfaces and is thus forced to deposit its solid materials. The stream impinges almost perpendicularly on the internal periphery of the drum, but only after an initial circuitous passage during which itimpinges against other faces or walls of each pocket.

The stream is again led back towards the outer peripheral surface of the pockets by deflection projections 25. Fig. 6 shows also the pivoted flap 2% and the pivotal prop 2| in the closing position.

A further deflection and deposition action is brought about by extending the exit path by means of a baflie plate 28, which is connected to and rotates with the discharges I6 and may be made as a sieve (see Figs. 4, 6 and 7). A drumend ring 21 connected to the inwardly directed side surface of the half of the drum II (see Figs. 4 and 6) may also be made as a sieve, and in this event the outgoing liquid, which but for the sieving perforations would have to pass over said ring, ultimately leaves some of the entrained solid materials deposited on the ring to be forced outwards towards the outer periphery of the pockets under centrifugal force. Scrapers 28 (see Fig. 5) 'continuously maintain the sieve 2i cleaned in proximity to the discharge zone.

Where the centrifuge has to deal with thickly fluid mixtures, the arrangement of deflecting projections 29 (see Fig. 8) in the converged discharges IG can be used with advantage instead of nozzles. These projections present inclined faces which propel the liquid radially outwards at increased speed.

In the modification according to Figs. 9 and 10, the constricted outlets for discharging the fluid mixture supplied to them through the inlet conduit are arranged on a separate channelled ring 29. The ring 29 is fixed to and rotates with the inner drum II. The outlets I6 of the structure I5, I5 are wider mouthed than in the former construction and they project to a short extent into the channel of the ring 28. The liquid discharged into the ring 29 accumulates in the form of a liquid ring 3| and produces an excess pressure sufllcient to produce the increased liquidspeed necessary in the small-bore discharge tubes 30 connected to the ring 29. Where as in the example theinner drum periphery is divided into deposition or separation pockets I9, there is one tube 30 for each pocket. These tubes 30 may extend as shown well into the pockets I9 seeing that the tubes and pockets rotate in unison. Thus, the discharged streams have to penetrate only a comparatively thin layer in order to reach the impingement faces, and so the disadvantage of discharging the streams into the pockets through a thick layer of liquid is obviated. Indeed, in large machines such a layer of liquid readily becomes so thick that the discharge-stream speed necessary to penetrate it would produce erosion and wear effects, with the result that enlargement of the discharges would take place and reduction of the discharge-stream speed would result. Another disadvantage obviated by the modification according to Figs. 9 and 10 is due to the feature that the discharge stream, in its initial circuitous passage in each pocket or cell preparatory to almost perpendicular impact with the internal periphery of drum II, does not become braked or thrown back for a short time when flowing past the walls of the pocket. Such a disadvantage carries with it the danger that a proportion of the solid matter would be entrained with backwardly flowing liquid.

The excess pressure necessary for production of the increased discharge-stream speed in the tubes 30 is obtained by virtue of the difference, or effective pressure head, between the liquid surfaces 3| and 32 in the channel of ring 29 and in the liquid ring, respectively. The liquid accumulated in the channeled ring 29 tends to remain, under the action of centrifugal force, as far as possible from the axis of rotation. Thus, the ring 29 can turn in unison with the drum ll without thereby causing the segmental form of the accumulated liquid to alter (see Fig. 9).

The fluid mixture to be separated can be supplied to the inlet conduit under pressure, especially in any case where the mixture is thickly fluid or viscous.

I claim:

1. A centrifuge comprising an annularhollow rotor defining an inwardly facing separation area having inwardly directed side' surfaces, said side surfaces under rotor rotation enclosing a centrifugally produced ring of liquid, a hollow rotatable structure coaxial to said rotor and provided with a hollow radial part to supply said liquid, the end of said radial part extending into said liquid ring closely towards the inside of said separation'surface, and means for rotating said rotor and structure, the radial part being provided at its end with a sudden constriction of its cross section to maintain a radially inner surface of an accumulation of a mixture of liquid and solid matters supplied by said hollow coaxial structure, said inner surface being at a lesser radius than the inner periphery of said ring of liquid, to effect separation of the solid matter from the liquid matter of said accumulated mixture by high-speed ejection thereof through said constriction and against said separation surface through said ring of liquid.

2. A- centrifuge according to claim 1, wherein said hollow radial part is provided with a projection on its inner surface, the rear side of said projection being inclined with respect to the axis of rotation, whereby to give an additional drive to said mixture in said hollow radial part in the radial direction.

3. A centrifuge according to claim 1, wherein said hollow radial part is subdivided by a hollow ring provided on said rotor open .on its inwardly facing circumference, a first hollow radial part ring and submerging into said annular hollowrotor, the cross section of said second hollow radial part being constricted with regard to the 0 cross section of said first hollow radial part.

HERBERT SCHULZ.

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