US3494546A

US3494546A - Centrifuge with variable discharge

Info

Publication number: US3494546A
Application number: US713474A
Authority: US
Inventors: Carl-Goran Nilson
Original assignee: Alfa Laval AB
Current assignee: Alfa Laval AB
Priority date: 1967-03-29
Filing date: 1968-03-15
Publication date: 1970-02-10
Anticipated expiration: 1987-02-10
Also published as: DE1657269A1

Description

Feb. 10, 1970 I CARL*GORAN NILSON 3,494,545

CENTRIFUGE WITH VARIABLE DISCHARGE 2 Sheets-Sheet 1 Filed March 15, 1968 INVENTOR.

M mv M v WWW W 10, 1970 CARL-GORAN NILSON 3,494,546

CENTRIFUGE WITH VARIABLE DISCHARGE I Filed March 15, 1968 2 Sheets-Sheet 2 U a U Q c) n 9 1: F) 1 co 51 N" I Ln I N y l (\J N \Y q- Qi Q en E United States Patent CENTRIFUGE WITH VARIABLE DISCHARGE Carl-Goran Nilson, Tullinge, Sweden, assignor to Alfa- Laval AJL, Tumba, Sweden, a corporation of Sweden Filed Mar. 15, 1968, Ser. No. 713,474

Claims priority, application Sweden, Mar. 29, 1967,

Int. Cl. B04b 11/05 US. Cl. 233-20 6 Claims ABSTRACT OF THE DISCLOSURE The centrifugal rotor contains an axially movable slide valve for opening and closing peripheral outlets from the separating chamber, this valve being actuated hydraulically by supplying an operating liquid to an adjacent space having two drain outlets of which one is nearer the rotor axis' than the other. A second valve is arranged to open and close the drain outlet located farther from the rotor axis, so as to effect intermittent discharge of the entire content of the separating chamber; and a third valve is arranged to open and close the other drain outlet so as to effect intermittent discharge of only part of such content.

THE DISCLOSURE The present invention relates to a centrifuge for intermittently effectingselectively either a partial or a total discharge of the rotor content, the centrifuge including a first valve actuated hydraulically in the longitudinal direction of the rotor axis to open and close outlets for a separated component (sludge or heavy liquid, such outlets being located in the wall of the rotor, and a second valve operable to open and close an outlet for the operating liquid which actuates the first valve.

Swedish patent specification 192,021 discloses a centrifuge which makesit possible to effect either partial or total discharge of the rotor content, as may be desired. The degree of discharge is determined by the period of time during which the second valve is kept open. Since the discharge of operating liquid through the second valve takes place with high velocity, the. control of the discharge time must be effected with an accuracy of hundredths of a second.

An object of the present invention is to make it possible, in a more reliable way than in'the 'prior centrifuge, to choose between partial and total discharge of the rotor content. More particularly, this is made possible by means of a third valve which opens an outlet for the same operating liquid as that previously mentioned, and this last outlet is located radially inside the first-mentioned operating liquid outlet. The two valves which effect discharge of operating liquid can be movable in a manner known per se, either axially or radially with respect to the rotor axis.

According to an embodiment of the invention, the position of the outlet opened and closed by the third valve is defined by the inner edge of an annular disc extending a distance inwardly from the periphery of the chamber which contains the operating liquid actuating the first valve. The position of the outlet and consequently the degree of partial discharge can be varied, as desired, by means of interchangeable annular discs having their inner edges located at different radial distances from the center of each disc. Intermittent partial discharge from the rotors separating space is effected by opening and closing the radially inner operating liquid outlet, and intermittent total discharge from such space is effected by opening and closing the radially outer operating liquid outlet. Due to the fact that the inner operating liquid Patented Feb. 10, 1970 ice valve can operate quite independently of the outer one, it is possible in each individual case to ensure either partial or total discharge without accurate control of the period of time for keeping the valves open.

In the embodiment having the aforesaid annular disc, it is possible to provide outlet nozzles for operating liquid which extent through the disc, in order to ensure total discharge.

If it is desired to effect very rapid total discharge, the second valve can be arranged so that when it opens it also opens the third valve. Then all the operating liquid flows out through the two valves simultaneously.

The invention is described more in detail below with reference to the accompanying drawings, in which FIGS. 1 and 2 are vertical sectional views of a centrifugal rotor embodying different forms of the invention. Corresponding details in FIGS. 1 and 2 have the same reference numerals.

In FIG. 1, the rotor body proper is shown at 1 and has a cover 2 which is retained by a lock ring 3. The liquid to be separated flows through a distributor 4 into the separating chamber 5 and a disc set 6 provided therein. The liquid is supposed to contain sludge, and separated sludge is. discharged under control of a piston valve 7 through openings 8 in the rotor wall. The rotor is driven by a spindle 9. Between the rotor bottom and the valve 7 is a space 10 for the operating liquid which actuates the valve. A ring valve 11 is provided with a sealing pad 12 for closing a channel 13 under the action of springs 14. There are actually three such pads 12 and channels 13 equally spaced around the rotor axis, so as to form a three-point support for the valve 11. An additional ring valve 15 is provided with sealing pads 16 for closing three channels 17 under the action of springs 18. The

springs

14 and 18 abut against a ring 19 secured to the rotor bottom. A stationary body 40, containing three

supply channels

20, 21 and 22 for operating liquid, surrounds the spindle 9. The channel 20 opens into a part of the body designed as a paring disc. The three channels open into

annular chambers

23, 24 and 25, respectively in the rotor bottom. A channel 26 extends from the chamber 23 to the space 10. A channel 27 extends from the chamber 24 to a space 28 above the valve 11. This space is drained by

channels

29 and 30. A channel 31 extends from the chamber 25 to a space 32 above the valve 15. This space is drained by

channels

33 and 34.

During normal separation, the space 10 is kept filled wlth operating liquid, usually water, from a suitable source such as a container in which a constant liquid level is maintained. The operating liquid fills the chamber 23 to the level of the opening of the channel 20, through which it is supplied. The pumping or paring action at the channel opening generates a pressure which balances the pressure from the liquid in the container. The pressure of the operating liquid in the space 10 keeps the valve 7 closed. If it is desired to discharge the rotor content completely, the supply of liquid to be separated as well as the supply of operating liquid through the channel 20 is interrupted. Furthermore, operating liquid is supplied through the channel 21. This liquid fills the space 28 and thus presses the valve 11 downward. The operating liquid in the space 10 is then rapidly thrown out through the

channels

13 and 30, which have a great draining capacity. The valve 7 is opened at the same time, and all of the content of the rotor is thrown out through the openings 8. When the springs 14 overcome the pressure of the discharging operating liquid, the valve 11 is closed. Liquid remaining in the space 28 is thrown out through the channel 29, which has a small draining capacity. Operating liquid can then be supplied through the channel 20, the valve 7 being closed. Thereafter, the supply of the liquid to be separated can be resumed.

When it is desired to discharge the rotor content only partially, neither the supply of the liquid to be separated nor the supply of operating liquid through the channel 20 is interrupted. Instead, there is supplied through the channel 22 a quantity of operating liquid adjusted to the degree of desired partial discharge. The maximum possible partial discharge is determined by the overfiow outlet formed by the channel 17. The operating liquid from channel 22 fills the space 32 and presses the valve 15 downward. Operating liquid in the space is then rapidly thrown out through the

channels

17 and 34, which have a great draining capacity, and through holes in the ring 19. When the springs 18 overcome the pressure of the discharging operating liquid, the valve is closed. Liquid remaining in the space 32 is thrown out through the channel 33, which has a small draining capacity but one which exceeds the supply capacity through the channel A liquid cushion remains in the space 10 and extends from the periphery of this space to a level which is determined by the radial position of the channels 17. Under the action of the pressure of the rotor content, the valve 7 is pressed downward and a part of the rotor content is thrown out through the openings 8. When the pressure of the liquid cushion remaining in the space 10 exceeds the pressure of the liquid remaining in the separating chamber 5, the valve 7 is closed. The space 10 is filled at the same time with liquid from the channel 20, and for this reason the valve 7 is kept closed also when the supply of the liquid to be separated is continued.

The embodiment according to FIG. 2 differs from the embodiment according to FIG. 1 in that the channel 17 determining maximum partial discharge has been replaced by an exchangeable annular disc 35. By an exchange of a disc 35 for another disc having a different inner diameter, another degree of maximum partial discharge can be reached. The disc 35 divides the outer part of the space 10 into an upper part 10a and a lower part 10b. The space 10a is drained by means of three outlet nozzles 13a, and the space 10b is drained by means of three outlet nozzles 17a. The nozzles 13a pass through the disc 35 and the rotor bottom, and the nozzles 17a pass through the rotor bottom and the ring valve 11. The springs 14 rest against the upper side of the ring valve 15, which is located right below the ring valve 11.

This device functions mainly in the same way as the device previously described, but with the following differences. When the rotor content is to be completely discharged, the ring valve 11 presses the ring valve 15 downward against the action of the

springs

14 and 18, so that the outlet nozzles 13a as well as the outlet nozzles 17a are opened. In this way, a more rapid draining of the space 10 and consequently a more rapid discharge of the rotor content is obtained than in the preceding device. When the springs 14 close the ring valve 11, the springs 18 at the same time close the ring valve 15, so that all nozzle outlets 13a and 17a are closed. Thereafter, operating liquid can again be supplied through the channel 20.

When partially discharging the rotor content, only the ring valve 15 is pressed down. Operating liquid from the space 10 is then thrown out through the nozzles 17a so that a liquid cushion remains only in the space 10a. This remaining cushion, when maximum possible partial discharge is effected, extends radially inward to the inner edge of the disc 35.

I claim:

1. In a centrifuge comprising a rotor mounted for rotation about an axis and having a separating chamber, the rotor having a wall provided with outlets for discharge of a separated component from said chamber and being adapted for intermittent discharge selectively of only part or all of the content of said chamber, the combination with said rotor of a first valve movable longitudinally of said axis to open and close said outlets, the rotor having a space for receiving an operating liquid to actuate said valve hydraulically, said space having first and second drain outlets for the operating liquid, said second drain outlet being located at a shorter radius from said axis than the first drain outlet, a second valve movable selectively to open and close said first drain outlet, and a third valve movable independently of the second valve to selectively open and close said second drain outlet.

2. The combination according to claim 1, comprising also an annular disc located in said space and extending radially inward from the peripheral portion of said space, the disc having an inner edge spaced radially outward from the inner portion of said space and defining the radial position of said second drain outlet.

3. The combination according to claim 2, in which said first drain outlet is formed by a nozzle extending through said disc.

4. The combination according to claim 1, comprising also an operative connection between said second and third valves for causing the second valve, when opening, to open the third valve.

5. The combination according to claim 1, in which the rotor has second and third spaces for receiving operating liquid to actuate said second and third valves, respectively, the combination comprising also means biasing each of said second and third valves in the direction opposite to the direction of its actuation by the operating liquid, and means for supplying operating liquid to each of said spaces.

6. The combination according to claim 5, in which said third valve is concentric to the second valve.

References Cited UNITED STATES PATENTS 6/1965 Thylefors 233-20 9/1966 Thylefors 233-20