US3272430A

US3272430A - Sluidge centrifuge

Info

Publication number: US3272430A
Application number: US316806A
Authority: US
Inventors: Thylefors Henric Wilhelm
Original assignee: Separator AB
Current assignee: Alfa Laval Holdings Amsterdam AB
Priority date: 1962-11-06
Filing date: 1963-10-17
Publication date: 1966-09-13
Anticipated expiration: 1983-09-13

Description

SePt- 13 1956 H. w. THYLEFoRs 3,272,430

SLUDGE CENT-RIFUGE Filed oct. 17, 196s Igg I N VEN TOR. Henr/'c Wilhelm Thylefors Fig. 2

United States Patent O 3,272,430 SLUDGE CENTREFUGE Henric Wilhelm Thylefors, Stockholm, Sweden, assigner to Aktieboiaget Separator, Stockholm, Sweden, a corporation of Sweden Filed Get. 17, 1963, Ser. No. 316,806 Claims priority, application Sweden, Nov. 6, 1962, 11,893/ 62 Claims. (Cl. 233-20) The present invention relates to .sludge centrifuges of the type adapted for intermittent discharge of centrifugally separated sludge. More particularly, the invention relates to a centrifuge of this type in which a first valve is actuated hydraulically in the longitudinal direction of the rotor shaft (axially) to open and close sludge outlets arranged in the wall of the rotor, and a second axially movable valve is actuated hydraulically to open outlets for the operating liquid which actuates the first valve, the second valve being subjected to a force acting constantly in the valve-closing direction.

Centrifuges of this type as proposed heretofore have been arranged for either total or partial discharge from the separation chamber. When separating liquids containingr sludge of a certain kind, such as beer wort, the centrifuge has been operated for only partial discharge from the separation chamber intermittently, in order to avoid wort losses. In those cases, however, it has been found that a hard-packed sludge layer is formed at the periphery of the sludge chamber, which sludge layer is similar to a wooden ring. This sludge ring has a detrimental etfect on the operation of the centrifuge and cannot be removed without dismantling and cleaning the centrifuge, thus requiring undesirable stoppages.

The present invention has for its object the provision of a centrifuge of the type described which eliminates this drawback by making it possible to effect a series of consecutive partial discharges from the separation chamber alternating with `at Aleast one total discharge from the separation chamber. Owing to the latter discharge or discharges, the sludge remaining from the partial discharges is flushed from the separation chamber so that the centrifuge can be operated, without being stopped for cleaning, for a considerably longer period of time than would otherwise be possible.

In a centrifuge made according to the present invention, the second valve is arranged so Ias to open 'and close two or more (preferably three) outlets located at different radial distances from `the rotor axis. At least the outermost one of these outlets must allow a total discharge from the separation chamber. According to a preferred embodiment of the invention7 three such outlets are provided, of which two are located at the same distance from the rotor axis and the third is located at a greater distance from the same axis. This larrangement ensures a rapid discharge of the operating liquid through all three outlets to a level determined by the inner outlets. Thereafter, the discharge of the operating liquid will continue at a slower rate since it now occurs only through the outermost outlet. This lag has the advantage that the discharge can be interrupted with a greater accuracy Iat a desired level and that, consequently, a desired degree of partial discharge from the separation chamber can be attained with greater reliability.

The supply of operating liquid for opening the second valve may, in principle, be effected manually. Such manual control is, however, difiicult to carry out with desired rapidity and accuracy in order to obtain a desired degree of partial discharge. The centrifuge is therefore preferably provided with la control device operable to supply a pre-determined quantity of operating liquid durice ing a certain period of time in order to open the second valve. This control device may take various forms. For example, it may comprise a valve located in a supply pipe for the last-mentioned operating liquid and arranged so as to be automatically kept open during a pre-determined period of time. In order to compensate for losses of operating liquid due to leakage when the centrifuge operates with both first-mentioned valves being closed, a connection may be provided between the inlet side and the outlet side of the last-mentioned valve, this connection being formed by a permanently open pipe having a `small crosssectional area.

The invention is described more in detail below, reference being made to the attached drawings in which:

FIG. 1 is a vertical sectional view of part of a centrifuge embodying the invention in a preferred form, with the rotor having a vertical axis of rotation, and

FIG. 2 is a diagrammatic View, on a reduced scale, showing the locations of the outlet holes for the operating liquid which actuates the valve for opening and closing the sludge outlets.

In the drawings, reference numeral 1 designates the rotor body having a cover 2 and a lock ring 3 which secures the cover to the rotor body. Relatively large sludge outlets 4 are evenly spaced around the periphery of rotor 1. While separation is in progress, these sludge outlets are maintained closed by means of a generally conical valve disk 5 which makes a sealing contact with the cover 2 by means of a ridge 6. A conventional set of conical disks 7 is located in the centrifugal separating chamber 9 of rotor 1. The liquid to be separated is conveyed into the separation chamber 9 by means of the usual distributor 8. The rotor is mounted on and drive-n by a vertical shaft 1t).

The valve disk 5 and the bottom of the rotor body 1 define beween them an annular interspace or chamber 11. Under the effect of centrifugal force, an operating liquid in chamber 11 generates the axial force required for closing the valve 5. An outer channel 12 and two inner channels 13 are provided for the discharge of liquid from the chamber 11. These channels are kept closed by a ring-shaped valve 14 provided with sealing pads 15 (of nylon, for example) each of which seals off its own channel outlet. A plate 16 is screwed -or otherwise secured to the bottom of the rotor body 1 and supports compression springs, one of which is shown at 17, spaced around the rotor axis. The springs 17 are compressed between plate 16 and valve 14 and act to urge valve 14 upwardly to its closing position, where pads 15 are seated against the outlet ends of the

respective channels

12 and 13.

The shaft 10 is surrounded by a stationary, cylindrical body 18 having a vertical channel 19 to which is connected a supply pipe 20 for an operating liquid, such as water. Plate 16 forms a ring-shaped chamber 21 surrounding the stationary body 18 and into which the channel 19 opens. A channel 22 leads from chamber 21 to the chamber 11. The chamber 21 is provided with draining holes 23 and communicates, by way of an overow outlet 24 and a channel 25, with a ring-shaped interspace 26 between the ringashaped Valve 14 and the bottom of the rotor body 1. The ring-shaped valve 14 closely surrounds a cylindrical surface 27 on the bottom of the rotor body 1 and is slidable vertically on this cylindrical surface 27 while maintaining sealing contact therewith. The chamber 26 is provided with drainage holes 28 arranged in the ring-shaped Valve 14.

A valve 29 is provided in the pipe 20 and is controlled on any suitable manner (for example, electrically) so as to be kept open automatically for a pre-determined period of time when the separation chamber 9 is to be partially discharged. The pipe 20 is fed from a suitable source of operating liquid (not shown), such as a vessel in which a liquid level is kept constant so that the flow rate through the valve 29 is kept constant as long as this valve is open. The inlet side and the outlet side of the valve 29 communicate with each other through a permanently open pipe 30 which has a small cross-sectional area.

The centrifuge operates as follows:

It is assumed that the centrifuge rotor 1 rotates with its valve disk 5 in closed position, as shown. Owing to the fact that the valve 29 is kept closed, water is supplied through the pipes 30 and Ztl at such a low rate that `the chamber 11 is kept lled only to that level which is determined by the fholes 23 through which all excess Water is ejected. When the separation chamber 9 is to be partially emptied by ejecting'sludge and only as little liquid as possible through the outlets 4, the rate of water supply is increased through the pipe by opening the valve 29 for an empirically pre-determined period of time. The Water level in the chamber 21 is then displaced radially inwards despite the continued escape of water through the holes 23, and water ows over the overflow outlet 24 and through the channel 25 into the chamber 26. When the water level in chamber 26 has increased sufficiently inwards despite the outow also occurring through the ydrainage holes 28, the liquid pressure in chamber 26 (aided by the liquid pressure against the pads 15) overcomes the closing power of the springs 17 so that the valve 14 opens the

channels

12 and 13. (See also FIG. 2.) The water then flows rapidly from chamber 11 through all three `

channels

12 and 13 until the water level in the chamber 11 recedes beyond the inner channels 13. Thereafter, water continues discharging only through the outer channel 12, but the displacement of the water level outwards in the chamber 11 now occurs at a slower rate. When the balance of forces is upset by a certain outward displacement of this water level, the valve disk 5 opens so that sludge is discharged through the outlets 4, whereupon the liquid level in the separation chamber 9 follows the outward displacement of the water level in the chamber 11.

When the valve 29 closes after the predetermined period of time, the water supply to the chamber 26 stops and the water remaining in this chamber is ejected through the holes 28. The springs 17 then close the valve 14, thus closing the

channels

12 and 13. The water remaining in the chamber 11 presses the valve disk 5 upwards against the pressure of the liquid remaining in the separation chamber 9 (when the latter liquid level has moved outward sufficiently) so that the outlets 4 are closed. By proper timing of the operation of valve 29, the outlets 4 are closed when substantially all of the sludge has been ejected but while the main body of liquid still remains in the separation chamber. During such a partial discharge from chamber 9, the supply of liquid to be separated to the separation chamber is not interrupted. At about the time when outlets 4 are closed as described above, valve 29 is again opened to ll chamber 11 to a level near the drainage holes 23. When this level is reached, the water supply is thereafter carried on through the pipe 30 only.

To obtain a total discharge from the separation chamber 9, the supply of the feed liquid through distributor 8 to this separation chamber is interrupted and the valve 29 is opened for a longer period of time than the predetermined period previously mentioned, that is, for a period sufficient to allow drainage of chamber 11 through channel 12 to the point where separating -chamber 9 is completely emptied through outlets 4 before any liquid remaining in chamber 11 can reclose the valve disk 5. Valve 29 is then reclosed to cause reclosure of valve 14 iand channels 12-13, as previously described, 4and is then opened again to rell chamber 11 with water to the level of holes 23 as previously mentioned. Thus, the sludge valve 5 will be held in its upper or closed position when the liquid to be separated is again supplied through distributor 8 to the separating chamber 9.

As will be readily understood by those skilled in the art, the liquid from which sludge is centrifugally separated in chamber 9 discharges in the usual manner through an outlet (not shown) located at the upper part of the rotor near its rotation axis.

It will be apparent that the parts 19 :and 2t) form with chamber 21 and channel 22 a means for delivering hydraulic liquid to the rst hydraulic chamber 11; and the parts 19 and 2t) form with chamber 21, overflow outlet 24 an-d channel 2S a means for delivering hydraulic liquid to the second hydraulic chamber 26.

I claim:

1. In a sludge centrifuge adapted for intermittent discharge of centrifugally separated sludge and comprising a hollow rotor mounted for rotation on an axis and having a separating chamber for receiving `a mixture of sludge and liquid to be separated from the sludge, the rotor having a peripheral outlet for discharging sludge from said chamber, the combination with said rotor of a tirst valve reciprocable in the rotor along the rotor axis between positions for opening and closing said sludge outlet, said valve defining with the rotor a first hydraulic chamber having a plurality of hydraulic liquid outlets located at different radii from the rotor axis, at least one of said hydraulic outlets being located at a greater radius from said axis than is the outer periphery of the separating chamber, a second valve reciprocable along said axis for opening and closing said hydraulic outlets, the second valve being biased toward a position for closing said hydraulic outlets and partly defining a second hydraulic chamber, said second valve being axially spaced from the rotor and defining therewith a discharge passage for said hydraulic outlets, said second valve having a plurality of sealing pads for engagement with the corresponding hydraulic outlets when the second valve is closed, hydraulic liquid delivery means communicating With said rst hyydraulic chamber for delivering liquid thereto to hold the first valve in its said closing position and thereby accumulate sludge in the separating chamber, said delivery means also communicating with said second hydraulic chamber for delivering hydraulic liquid to the second hydraulic chamber to actuate said second valve away from its said closing position and thereby open said hydraulic outlets, whereby hydraulic liquid is drained from said first hydraulic chamber at a relatively high rate through all of said hydraulic outlets and then at a lower rate through said one hydraulic outlet, and whereby said one hydraulic outlet allows total discharge from the separating chamber.

2. The combination according to claim 1, in which said hydraulic outlets include two outlets located at the same distance from the rotor axis and a third outlet located at a greater distance from said axis.

3. The combination according to claim 1, in which said two delivering means include a common supply pipe for hydraulic liquid.

4. The combination according to claim 1, in which said two ldelivering means include a common supply pipe for hydraulic liquid, and a control valve in said pipe.

5. The combination according to claim 1, in which said two delivering means include a common supply pipe for hydraulic liquid, a control valve in said pipe, and a bypass pipe interconnecting the inlet and outlet sides of said control valve.

References Cited by the Examiner UNITED STATES PATENTS 2,955,754 10/1960 Nyrop 233-20 3,062,228 11/1962 Heath 137-268 X FOREIGN PATENTS 1,284,378 1/1962 France.

M. CARY NELSON, Primary Examiner. H. T. KLINKSIEK, Assistant Examiner.

Claims

1. IN A SLUDGE CENTRIFUGE ADAPTED FOR INTERMITTENT DISCHARGE OF CENTRIFUGALLY SEPARATED SLUDGE AND COMPRISING A HOLLOW ROTOR MOUNTED FOR ROTATION ON AN AXIS AND HAVING A SEPARATING CHAMBER FOR RECEIVING A MIXTURE OF SLUDGE AND LIQUID TO BE SEPARATED FROM THE SLUDGE, THE ROTOR HAVING A PERIPHERAL OUTLET FOR DISCHARGING SLUDGE FROM SAID CHAMBER, THE COMBINATION WITH SAID ROTOR OF A FIRST VALVE RECIPROCABLE IN THE ROTOR ALONG THE ROTOR AXIS BETWEEN POSITIONS FOR OPENING AND CLOSING SAID SLUDGE OUTLET, SAID VALVE DEFINING WITH THE ROTOR A FIRST HYDRAULIC CHAMBER HAVING A PLURALITY OF HYDRAULIC LIQUID OUTLETS LOCATED AT DIFFERENT RADII FROM THE ROTOR AXIS, AT LEAST ONE OF SAID HYDRAULIC OUTLETS BEING LOCATED AT A GREATER RADIUS FROM SAID AXIS THAN IS THE OUTER PERIPHERY OF THE SEPARATING CHAMBER, A SECOND VALVE RECIPROCABLE ALONG SAID AXIS FOR OPENING AND CLOSING SAID HYDRAULIC OUTLETS, THE SECOND VALVE BEING BIASED TOWARD A POSITION FOR CLOSING SAID HYDRAULIC OUTLETS AND PARTLY DEFINING A SECOND HYDRAULIC CHAMBER, SAID SECOND VALVE BEING AXIALLY SPACED FROM THE ROTOR AND DEFINING THEREWITH A DISCHARGE PASSAGE FOR SAID HYDRAULIC OUTLETS, SAID SECOND VALVE HAVING A PLURALITY OF SEALING PADS FOR ENGAGEMENT WITH THE CORRESPONDING HYDRAULIC OUTLETS WHEN THE SECOND VALVE IS CLOSED, HYDRAULIC LIQUID DELIVERY MEANS COMMUNICATING WITH SAID FIRST HYDRAULIC CHAMBER FOR DELIVERING LIQUID THERETO TO HOLD THE FIRST VALVE IN ITS SAID CLOSING POSITION AND THEREBY ACCUMULATE SLUDGE IN THE SEPARATING CHAMBER, SAID DELIVERY MEANS ALSO COMMUNICATING WITH SAID SECOND HYDRAULIC CHAMBER FOR DELIVEING HYDRAULIC LIQUID TO THE SECOND HYDRAULIC CHAMBER TO ACTUATE SAID SECOND VALVE AWAY FROM ITS SAID CLOSING POSITION AND THEREBY OPEN SAID HYDRAULIC OUTLETS, WHEREBY HYDRAULIC LIQUID IS DRAINED FROM SAID FIRST HYDRAULIC CHAMBER AT A RELATIVELY HIGH RATE THROUGH ALL OF SAID HYDRAULIC CHAMBER AT A RELATIVELY HIGH RATE THROUGH SAID ONE HYDRAULIC OUTLET, AND THEN AT A LOWER RATE THROUGH OUTLET ALLOWS TOTAL DISCHARGE FROM THE SEPARATING CHAMBER.