US 3250463 A
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United States Patent SELF-OPENING CENTRIFUGAL SEPARATOR Henric Wilhelm Thylefors, Stockholm, Sweden, assignor to Aktiebolaget Separator, Stockholm, Sweden, a corporation of Sweden Filed Jan. 23, 1963, Ser. No. 253,395 Claims priority, application Sweden,-Jan. 31, 1962, 1,063/62; Oct. 1, 1963, 185,425 5 Claims. (Cl. 23320) The present invention relates to self-opening centrifugal separators of the type in which the opening and closing movements of the valve slide are controlled by means of an operating liquid and wherein at least one of the sliding surfaces of the valve slide is sealed against the rest of the rotor by a gasket. The invention has particular reference to an improved separator of this type and a method of operating it.
In the operation of a separator of this type which is used to separate sludge from a liquid, there is a tendency for sludge to penetrate between the gasket and the sliding surface of the valve slide when the latter is closed and the pressure in the separation chamber of the rotor is thus high.
According to the present invention this drawback is eliminated in that, while the separator is in operation, a liquid is fed radially to the inner side of the gasket before the valve slide is closed, thereby increasing the sealing pressure of the gasket. Due to the action of the centrifugal force on the liquid thus supplied, this liquid will exert the required sealing pressure on the gasket.
In a centrifugal separator made according to the invention, the inner side of the slide valve gasket (the side facing the rotor axis) communicates radially inward with a lquid supply chamber in the rotor, and a device is provided for supplying a liquid to this chamber while the separator is in operation and before the valve slide closes. The chamber is preferably closed for a certain distance inward from the inside of the gasket, that is, it is free from drain outlets or the like, so that liquid remaining in the chamber exerts a pressure on the gasket even after the valve slide has opened.
Although the invention is applicable to gaskets on the outer sliding surface of the valve slide, it is particularly useful in connection with gaskets on the inner sliding surface of the valve slide. In the latter case, it is possible to apply the pressure liquid to a plurality of gaskets spaced axially from each other on the same sliding surface of the valve slide.
The valve operating liquid and the liquid producing the sealing pressure on the valve gasket may be fed to the rotor by means of separate devices. According to a preferred embodiment of the invention, the same liquid (such as water) is used for the operation of the valve slide and for the production of the sealing pressure, this liquid being admitted into the chamber behind the gasket. This chamber may communicate by way of a level-maintaining outlet (such as a paring member but preferably a simple overflow outlet) with the chamber from which the operating liquid controls the opening and closing movements of the valve slide. This provides automatically the advantage that the required sealing pressure is built up before the liquid is fed, by way of such outlet, into the control chamber of the valve slide and closes the latter.
The invention is explained more in detail below, reference being made to the attached drawing in which the single illustration is a vertical sectional view through the axis of a separator embodying a preferred form of the invention, only one-half of the section being shown.
In the drawing, reference numeral 1 deginates the 3,250,463 Patented May 10, 1966 rotor body proper and reference numeral 2 designates the appurtenant cover which is secured to the rotor body by means of a locking ring 3. The rotor body is carried by a driving shaft 4. The sludge-containing liquid is fed through the usual distributor 5 into the separating space 19 containing a set of conical discs 6. Sludge is periodically discharged through openings 7 in the wall of the rotor body. An annular valve slide 8 opens and closes thoses openings. The valve slide is operated by means of a liquid which is fed to a chamber 10 by generally radial channels 9, chamber 10 being provided with radial drainage channels 11. Annular gaskets 12 and 12a are fitted in circular grooves in the rotor body, these grooves being concentric to the shaft 4. The inner sides of the gaskets 12 and 12a communicate through generally radial channels 13 and 13a, respectively, with an annular recess 14 in the rotor body. By means of an overflow edge 15, the recess 14 communicates with another annular recess 16 from which channels 9 extend outwardly. The recess 16 is also provided with an overflow edge 17 located at a greater radius than overflow edge 15. Liquid is fed into the recess 14 by means of a stationary pipe 18. Reference numeral 20 designates the inner surface of the slide 8, against which the gaskets 1212a seal.
While separation is in progress, the valve slide 8 is maintained closed (in its uppermost position) by supplying liquid through the pipe 18 at such a rate that the chamber 10, the channels 9, 13 and 13a as well as the recesses or chambers 14 and 16 are kept filled with liquid in spite of the discharge of liquid through the drainage outlets 11 and over the overflow outlet 17. When the sludge collected in the separating space 19 is to be discharged, the supply of liquid to the pipe 18 is interrupted. Under the action of the centrifugal force, all the liquid contained in the recess 16, the channels 9 and the chamber 10 is ejected through the channels 11. Thus, the pressure on the underside of the valve slide 8 is released and the valve slide is pushed downward by the pressure in the rotor space 19. Thereupon, the sludge collected in the rotor is ejected through the peripheral openings 7. Meanwhile, part of the liquid contained in the channels 13 and 13a as well as in the recess 14 will normally leak out along the valve slide surface 20, so that the sealing pres-ore applied on the gaskets 12 and 12a decreases.
Since the liquid pressure in the chamber 10 is released before the valve slide 8 opens, the sludge in the separation chamber 19 has a propensity to penetrate into the slight clearance at the inner surface 20 of the valve slide. The sludge is prevented from penetrating further downward in this clearance by the gasket 12, since this gasket remains strongly pressed against the valve slide 8 by the liquid remaining in the channel 13 and the recess 14. When the valve slide 8 is re-closed, a pressure is again built up in the rotor space 19. In order to prevent this pressure from forcing sludge beyond the gasket 12, the required sealing pressure is restored before the valve slide 8 re-closes. This is eifected by again supplying liquid through the pipe 18, which liquid first fills the recess 14 to the level of the overflow outlet 15. Thus, the required sealing pressure is bulit up on the gaskets 12-12a before the liquid can flow over the overflow outlet 15 into the recess 16 and through the channels 9 to re-fill the chamber 10, as required to force the valve slide 8 upward so that the openings 7 are closed. The liquid supply through the pipe 18 is thereafter kept at such a rate as to compensate for the discharge through the channels 11.
The sealing efiect is increased by the additional gasket 12a with appurtenant channels 13a which function in the same way as the gasket 12 and the channels 13.
If an operating liquid (such as water) is used which is not to be mixed with the liquid (such as organic solvent) being separated, it is of importance that the gaskets 12 and 12a also prevent the liquid in the chamber 10 from penetrating along valve surface 20 into the separation chamber 19. It will be apparent that the feed pipe 18 forms a'means for supplying liquid to chamber 14 while the valve slide 8 is in its opening position, so that gaskets 1212a are pressed against the slide by the liquid in the respective channels 1313a. The overflow outlet 15, chamber 16 and channels 9 form means for supplying operating liquid to valve slide 8 to control its movements.
1. A self-opening centrifugal separator comprising a hollow rotor having a separating space and also having a peripheral outlet for discharging separated sludge from said space, a valve slide mounted in the rotor for movements between a position for closing said outlet and a position for opening said outlet, the slide having a surface slidable relative to the rotor, a sealing gasket in the rotor engaging said slide surface, the rotor having a chamber located between the gasket and the rotor axis and communicating with the inner side of the gasket facing said axis, the rotor also having a channel for directing an operating liquid to the valve slide, and means communicating with said chamber and channel for first supplying liquid'to said chamber while the valve slide is in its opening position and prior to movement of said slide to its closing position, to press the gasket against said surface, and then supplying liquid to said channel to move the valve slide toward its closing position.
2. A separator according to claim 1, in which the rotor has a closed channel extending generally radially outward from said chamber to said inner side of the gasket.
3. A separator according to claim 1, in which said slide surface faces the rotor axis.
4. A self-opening centrifugal separator comprising a hollow rotor having a rotor axis and a separating space and also having a peripheral outlet for discharging -the rotor for movements between a positio-nfor closing said outlet and a position for opening said outlet, the slide having a surface slidable relative to the rotor, a sealing gasket in the rotor engaging said slide surface, said gasket having an inner side facing the rotor axis, the rotor having first and second chambers located between the gasket and the rotor axis, the first chamber communicating with the inner side of the gasket which faces said axis and having a level-maintaining outlet leading to the second chamber, said second chamber communicating with the valve slide to direct operating liquid to the end of said slide remote from said outlet for closing the slide, and a device adjacent said first chamber for supplying liquid to said first chamber, to press the gasket against said slide surface, whereby the valve slide is adapted to be closed by liquid supplied from said device to the second chamber by way of the first chamber and said level-maintaining outlet.
5. A separator according to claim 4, in which said level-maintaining outlet is an overflow outlet.
References Cited by the Examiner UNITED STATES PATENTS M. CARY NELSON, Primary Examiner.
ROBERT F. BURNETT, Examiner.