US3167509A

US3167509A - Centrifugal separator

Info

Publication number: US3167509A
Authority: US
Inventors: Steinacker Peter
Original assignee: Westfalia Separator GmbH
Current assignee: GEA Mechanical Equipment GmbH
Priority date: 1961-06-13
Filing date: 1962-06-12
Publication date: 1965-01-26
Anticipated expiration: 1982-01-26
Also published as: NL278887A; NL122277C; DE1145100B

Description

P. STEINACKER 3,167,509

CENTRIFUGAL. SEPARATOR 2 Sheets-Sheet 1 Jan. 26, 1965 Filed June 12, 1962 INVENTOR. PETE/3 SFV YACKE Q 1mm m. WW

Jan. 26, 1965 P. STEINACKER CENTRIFUGAL. SEPARATOR 2 Sheets-Sheet 2 Filed June 12, 1962 United States Patent 3,167,509 CENTRIFUGAL SEPARATOR Peter Steinaclrer, Gelde, Westphalia, Germany, assignor to Westfalia Separator AG., Uelde, Westphalia, Germany, a corporation of Germany Filed June 12, 1962, Ser. No. 261,922 Claims priority, application Germany, June 13, 1961, W 3%,161 Ill 82b 5 Claims. (Cl. 23320) The present invention relates to centrifugal separators, and more particularly to the type of automatic self-cleaning bowl-type separators wherein solids or sludge accumulating inside the bowl is periodically discharged from the sludge space in the bowl while the unit continues to run at full speed.

The de-sludging cycle may be manually controlled. It has also been proposed to provide automatic timing units for actuating solenoid valves forming part of control means for setting the sludge discharge periods. The centrifuging time periods between the intermittent desluding periods may be readily determined by examining the solids content of the slurry or liquid mixture fed to the separator and relating the solids content to the throughput of the separator bowl and the sludge space volume of the bowl. Time switches controlled, for instance, by rotating cam means and the like may then be used to energize a control circuit connected to solenoid valves designed to enable the opening and closing of ports for the intermittent discharge of the sludge from the bowl.

When time switches are used for the control of the desludging cycle, the de-sludging cycle frequency is pro-set, regardless of the amount of sludge in the bowl at any given time during the centrifuging operation. However, a trouble-free operation of the separator bowl can be had only if the sludge discharge ports are opened at the exact time when the sludge space of the bowl is just filled with sludge. If the ports are opened before that time, a lot of useful liquid is lost with the discharged solids and the operation is, therefore, wasteful. If the ports are opened after the sludge space has been filled with sludge, solids will back into the channels of the separator disc set in the center of the bowl and thus impair the clarification of the liquid.

Therefore, timing units for the control of the de-sludging cycle presuppose first of all that the solids content of the slurry or liquid mixture to be centrifuged has been exactly predetermined and that the cycle, therefore, has been exactly calculated and set. Furthermore, they also assume that the throughput of the separator bowl and the solids content of the slurry or liquid mixture remain unchanged during the entire operation of the separator.

In practice, however, the separator receives its charge in many plants from large storage tanks. As the liquid is fed from the tank to the separator, the liquid level in the tank will be constantly lowered, causing a concomitant decrease in the static pressure and a lessening of the throughput. On .the other hand, gravity will cause the solids to settle near the bottom of the tank so that the solids content of the charge entering the separator will also change during the operation. With these changes in the assumed constants, which have become variables, timing units lose their accuracy.

It has also been proposed to connect the sludge space outside the disc set with a hydraulic cylinder chamber, in which a sliding piston moves to close the sludge discharge port means of the bowl, by means of a small tube so that clarified liquid flows from the sludge space to the chamber and thus keeps the piston in its port closing position. When, however, sufiicient sludge is formed to prevent further liquid from entering the tube, a small port in the chamber permits fluid to escape therefrom and the sliding piston moves to open the port means for the sludge discharge from the bowl. As sludge is removed, the inlet of the tube becomes free again to receive clarified liquid, the hydraulic cylinder chamber is filled, and the piston again closes the discharge port means in the bowl. Such a separator bowl accordingly operates constantly in a labile or unstable condition.

In another known apparatus of this type, a small tube conducts clarified liquid from the space outside the disc set to a storage vessel which has an opening in its bottom and which rests on a scale. Before the sludge space is filled with sludge, a uniform amount of liquid flows through the tube into the vessel and an equal amount of liquid flows out of the vessel through its bottom opening. A counterweight of the same weight as the filled vessel keeps the scale in balance. As soon as solids begin to clog the tube and prevent liquid flow therethrough, the arm of the scale carrying the counterweight pivots downwardly and closes a switch which opens the sludge discharge port means of the bowl. However, in such an arrangement, the counterweight or the vessel must be changed with different specific weights of different slurries fed to the centrifuge. Also, depending on the sensitivity of the scale, even the smallest changes in the liquid flow may cause opening of the bowl.

It is the primary object of the present invention to overcome all these disadvantages of the prior art and to provide an automatic, self-cleaning separator bowl the desludging cycle of which is controlled by a predetermined level of the solids layer in the sludge space.

Generally, the invention relates to centrifugal seperators of the de-sludging type with periodical discharge of the separated solids through openings in the wall of the bowl which openings can be opened and closed by an axially movable piston arranged in the interior of the bowl. Such automatic, self-cleaning separator bowls comprise a rotatable bowl and conical disc means mounted concentrically about the bowl axis and having an outer edge spaced from the bowl periphery. The outer edge of the disc means and the bowl periphery define a sludge space, and a stationary feed means, such as a vertical pipe, is arranged coaxially in the bowl to feed a slurry or liquid mixture to the conical discs. The centrifugal force generated during rotation of the bowl causes the heavy components, including the solids, to be thrown outwardly of the disc means and the solids or sludge accumulate in the sludge space. A sludge discharge means including port means in the bowl periphery is provided for intermittently discharging sludge from the sludge space. Means is provided for intermittently opening the sludge port means and control means is provided for actuating the means for opening the sludge discharge port means intermittently.

In such a separator bowl, it is proposed in accordance with this invention to arrange at least one conduit means having one end adjacent the outer edge of the disc means, the conduit. means connecting the sludge space with the intake of a centripetal pump means. The centripetal pump means, which are also designated as peeling discs, is arranged in the bowl concentrically about the feed means and a pressure sensitive device is mounted in the output of the centripetal pump means. The output of the centripetal pump means has an outlet port means permitting liquid to escape therefrom, which outlet may be connected to the feed means of the bowl, the feed chamber in the bowl, or the discharge means for the clarified liquid. The pressure sensitive device is operated by the pressure in the output and is operatively connected to the control means for actuating the opening of the sludge discharge port means.

Thus, some of the liquid component clarified in the channels between the conical discs will be discharged through the conduit means and the centripetal pump means. A conduit leading from the output of the pump means will return the clarified liquid from the output to the feed chamber of the bowl or to the storage tank. If desired, it may also feed the liquid directly to the clarified phase of the liquid preferably discharged through another centripetal pump means.

With this arrangement, the amount of liquid fed through the conduit means to the first-named centripetal pump means will automatically decrease when the solids layer in the sludge space has reached the one end of the conduit means adjacent the disc means, causing a corresponding decrease in pressure in the output of the pump means. The pressure sensitive device is pro-set to a certain minimum pressure and when the pressure in the output falls below it, it will cause actuation of the de-sludgingcycle control means.

in a preferred embodiment, the one end of the conduit means is of enlarged diameter so that accumulation of solids at this end of the conduit means is avoided. For the sake of better balance during rotation of the bowl, it is preferred to provide two conduits arranged diametrically opposite to each other in the bowl. The above and other objects, advantages and features of the present inventionwill become more apparent when the same is considered in the following detailed description the liquid componentfrom the space outside the conical disc set is returned to thefeed chamber of the bowl while the clarified liquid is discharged from the bowl under pressure by means of centripetal pump means. The

illustrated automatic de-sludger with its self-cleaning bowl is particularly suitable for continuous processing of materials that have a relatively high solids content. Continuous operation of the separator bowl is possible be cause the solids can be discharged from the bowl while the unit is running at full speed, thus eliminating the time consuming and often disagreeable chore of manual bowl cleaning. Furthermore, the basic design of this unit is such that conversion to other types of centrifugals through simple exchange of a few bowl parts will adapt the machine for separation and purification, extraction and clarificationf V a I r The bowl'consistsof a bottom wall 11 and a conical 'upper wall 2, the peripheral cylindrical portion of the bottom wall being connected'to the upper wall by seal- 7 ing ring 3 which threadedly engages one or both walls.

A peripheral sludge space'ZZ is defined in the interior of' the bowl by the upper wall 2. and a separating wall 5, a liquid cha distributors being fixedly connected tothe separating wall 5. An axially slidable, pressure fluid operated, annular piston is mounted in a pressure fluid cylinder defined by the bottom wall 1 of the bowl and the separator wall 5, an annular skirt 6a extending upwardly from the piston and sliding in an annular space between the periphery of the separator wall 5 and the bottom wall ll of the bowl.

The separator wall 5 has a first wall portion 5' which is generally parallel to the conical upper wallv 2 of the bowl and, ascending therefrom, a second Wall portion 5" extending towards upper bowl wall '2 but defining therewith an annular gap '7'. The cylindrical periphery of the bowl wall 1 defines several ports 7 in alignment with the gap 7. The sliding skirt 6a is designed to open and close communication between the gap 7' and ports 7 upon axial movement of the piston 6, the gap and ports constituting a sludge discharge port means in the periphery of the bowl upon opening of communication between the gap and the ports by the pressure fluid operation of piston 6. The pressure fluid cylinder is divided by the piston into a discharge means opening chamber 11 and a closing chamber 8.

The piston is maintained in the illustrated sludge discharge means closing position by a resiliently compressible mass arranged in chamber 8 or by supplying a pressure fluid thereto through suitable pressure fluid supply conduit means (not shown), in a manner well known er se. If de-sludging is desired, pressure fluid is supplied to piston opening cylinder chamber 11 through the main conduit 9 which supplies a suitable pressure fluid, such as water, through the bore It in the bowl hub to chamber 11; The supply of pressure fluid through conduits 9,19 must exceed the amount of fluid escaping through aligned bores 12, 13 in the piston and the cylindrical periphery of the. bowl so as to raise the level of pressure fluid :in the opening chamber. Assoon as the pressure in chamber Ill exceeds that in chamber 3, the piston 6 is forced downwardly and opens the sludge discharge means. The downward movement of the annular piston also causes the fluid in the chamber 8 to be inwardly displaced but the displacement of the free level of the fluid in this chamber is limited by an overflow bore 14 in the bottom wall 1.

When the de-sludging cycle is completed and it is desired to close the sludge discharge means again, valve 15 in supply main 9 is closed to cut off further pressure fluid supply to chamber 11. Pressure fluid continues to escape from the rotating bowl through

bores

12 and 13 through an annular communicating chamber 43 in the interior of the wall 1 around bore 13 designed to maintain communication between

bores

12, 13 in different axial positions of the piston. Escape of pressure fluid from chamber 11 will release the downward pressure on the piston and the resiliently compressible mass or pressure fluid in closing chamber e3 will aagin becomeeifective to move the piston upwardly and close the sludge discharge port Jeans.

' The liquid chargeto be clarified in the separator enters the bowl through the feed pipe 16 mounted along the axis of rotation of the bowl and discharging the. liquid in the feedlchamber 1 5 defined by the annular baflle means or distributor 4, whence it flows, through channel 7 means 19 and it) into the conical disc set 21 mounted coaxially about the baffle means and being'repres'ented f by a single disc, for the'sake of clarity of illustration. An

inlet valve Win the feed pipe controls thefeeding of the liquid charge into the separator bowl. a

Upon rotation of the bowl on shaft 4 which is connected to any suitable power source (not shown), the

specifically heavier solids content' of the liquid is thrown outwardly by centrifugal force andaccumulates in sludge space 22 between the outer edge of the disc set 21 and the periphery of the bowl. The-clarified liquid component, which is lighter, rises in the channels between the conical discs and passes through

discharge conduits

23 and 24 to the centripetal pump means chamber 25 defined by the neck portion 45 and cover 46 of the bowl. An annular paring disc or centripetal pump 26 removes the clarified liquid continuously and under pressure from chamber 25, the rotation of the chamber 25 about the stationary disc 26 causing a suction force which presses the liquid through the radial channel in the disc into the discharge conduit 27.

All of the above-described structure is conventional in separator bowls and merely constitutes one form of selfcleaning bowl to which the present invention may be applied.

According to the invention, an outlet conduit 28 leads from the space outside the conical disc set 21 to a special centripetal pump means chamber 29. The inlet 42 of conduit 28 is arranged adjacent the outer edge of the disc means and normally receives liquid accumulating in the peripheral chamber 22 unless it is shut olf by sludge. The liquid component rises through outlet conduit 28 into the centripetal pump means chamber 29 which is defined by the uppermost disc and an annular separating wall 47 extending inwardly from bowl neck portion 45 to separate chamber 29 from chamber 25. This liquid component is sucked continuously and under pressure from chamber 29 through a radial intake channel in the stationary paring disc 30 into the pump output which has a branch conduit 31. At the end of the pump output conduit 31, there is mounted a pressure sensitive device actuated by the pressure in the output conduit and constituted in the illustrated embodiment by a contact manometer 32 of known construction.

As long as outlet conduit 28 feeds liquid into the centripetal pump chamber 29, the stationary pump disc 30 intake channel, which stands still, will suck in the liquid from the chamber, converting the rotating energy of the.

liquid into pressure causing the liquid to flow inwardly as long as the bowl is rotated. The manometer is set so that this predetermined pressure in the pump output conduit 31 keeps the movable contact 34 away from stationary contact 35, thus keeping the electrical control circuit 48 out of operation.

In the embodiment of FIG. 1, the liquid sucked into the stationary disc 30 is returned from the pump outlet through a calibrated bore 36 into the feed chamber 18 of the bowl where it mixes with the liquid charge.

When solids or sludge in sludge space 22 have accumulated to the point where it blocks the inlet to conduit 28, no further liquid is delivered to the centripetal pump 30. The pressure in pump outlet conduit 31 decreases correspondingly and the manometer closes contacts 34, 35. Closing of the electrical circuit connected to contacts 34, 35 causes the conventional programming unit 33 in the electrical control circuit 48 to be actuated. Energization of unit 33 causes this control circuit to close solenoid valve 17, thus shutting off further supply of liquid charge to the bowl, while solenoid valve 15 is opened to supply pressure fluid through conduit 9 to the piston opening chamber 11. Piston 6 is thus forced downwardly and opens the sludge discharge port means'7', 7. The sludge in the sludge chamber is now thrown outwardly through the discharge port means by centrifugal force created by the continuously rotating bowl.

The programming device 33, which may take any suitable form and forms no part of the present invention, will open valve 15 and close valve 17 after it has received the operating impulse from contact manometer 32.

When no current is supplied to electrically controlled

valves

15 and 17, both valves are closed. Two manually controlled

valves

40 and 41 are arranged ahead of the

solenoid valves

15 and 17, respectively. Both of these valves are manually opened at the beginning of the centrifuging operation. The programming unit 33 is then actuated to open valve 17 to initiate the liquid charge supply to the bowl. The subsequent programming of the de-sludging cycles has been described hereinabove.

It is preferred to provide the outlet conduit 28 with a flared inlet 42 of increased diameter to facilitate the centrifugal removal of solids penetrating into the outlet conduit.

The embodiment shown in FIG. 2 is generally similar to the bowl of FIG. 1, like parts having been designated by like reference numerals to obviate a duplication of description, and differs therefrom only in the following aspects:

(1) Instead of providing a centripetal pump removal of the clarified liquid from the bowl, the

discharge conduits

23, 24 lead into a chamber 49 defined by separating wall 47' and a regulating disc 38 mounted on the neck portion of the bowl by threaded ring 50. The clarified liquid flows out of chamber 49 over disc edge 37 into a suitable receptacle (not shown). The chamber 49 is separated from the centripetal pump chamber 29 by the annular separating wall 47' and an annular baffle member 7 extending inwardly from the centripetal pump output conduit wall.

(2) Also, instead of guiding the liquid from the centripetal pump outlet back into the feed chamber of the bowl to be mixed there with the liquid charge, this liquid component is directed to the clarified liquid by calibrated bore 39 connecting the output conduit 31 with chamber 49.

It will be obvious from the above description that this arrangement controlls the de-sludging cycles independently of any pre-set time and solely in dependence on the amount of sludge in the sludge space.

While the invention has been described in connection with certain preferred embodiments, it will be clearly understood that many variations and modifications may occur to the skilled in the art, particularly after benefiting from the present teaching, without departing from the spirit and scope of this invention as defined in the appended claims.

I claim:

1. An automatic, self-cleaning centrifugal separator, comprising a rotatable bowl having an axis and a periphery, conical disc means mounted concentrically about the bowl axis and having an outer edge spaced from the bowl periphery, the outer edge of the disc means and the bowl periphery defining a sludge space, a stationary feed means coaxially arranged in said bowl, a centripetal pump means arranged in said bowl concentrically about said feed means, said centripetal pump means having an intake and an output, said output having an outlet port means, a conduit means connecting said sludge space and said centripetal pump means intake, an inlet end of the conduit means being adjacent the outer edge of the disc means, sludge discharge port means in the bowl peripherytor intermittently discharging sludge from said sludge space, means for intermittently opening the sludge discharge port means, a pressure sensitive device in the output of the centripetal pump means and operated by the pressure in the output, control means for actuating the means for opening the sludge discharge port means intermittently, and means operatively connecting the pressure sensitive device to the control means.

2. The centrifugal separator of claim 1, wherein said inlet end of the conduit means has an enlarged diameter.

3. The centrifugal separator of claim 1, wherein said outlet port means is in communication with said feed means. I

4. The centrifugal separator of claim 1, wherein said bowl defines a central feed chamber, said feed means leads into the central feed chamber in said bowl and said outlet port means is connected with said feed chamber.

5. The centrifugal separator of claim 1, further comprising means for discharging clarified liquid from said bowl and said outlet port means is in communication with said last-named discharge means.

(References on following page) References Cited by the Examiner UNITED STATES PATENTS Lindgren.

Lindgren 233-22 X Lindgren et a1. 233 -20 Nyrop 233-20 Steinacker et a1 233--2O FOREIGN PATENTS 11/48 Denmark. 2/ 37 Great Britain. 1 4/ 38 Great Britain. 5/59 Great Britain.

' 9/42 Sweden. '3/62 Sweden.

NORMAN YUDKOFF, Primary Examiner.

ROBERT F. BURNETT, Examiner.

Claims

1. AN AUTOMATIC, SELF-CLEANING CENTRIFUGAL SEPARATOR, COMPRISING A ROTATABLE BOWL HAVING AN AXIS AND A PERIPHERY, CONICAL DISC MEANS MOUNTED CONCENTRICALLY ABOUT THE BOWL AXIS AND HAVING AN OUTER EDGE SPACED FROM THE BOWL PERIPHERY, THE OUTER EDGE OF THE DISC MEANS AND THE BOWL PERIPHERY DEFINING A SLUDGE SPACE, A STATIONARY FEED MEANS COAXIALLY ARRANGED IN SAID BOWL, A CENTRIPETAL PUMP MEANS ARRANGED IN SAID BOWL CONCENTRICALLY ABOUT SAID FEED MEANS, SAID CENTRIPETAL PUMP MEANS HAVING AN INTAKE AND AN OUTPUT HAVING AN OUTLET PORT MEANS, A CONDUIT MEANS CONNECTING SAID SLUDGE SPACE AND SAID CENTRIPETAL PUMP MEANS INTAKE, AND INLET END OF THE CONDUIT MEANS BEING ADJACENT THE OUTER EDGE OF THE DISC MEANS, SLUDGE DISCHARGE PORT MEANS IN THE BOWL PERIPHERY FOR INTERMITTENTLY DISCHARGING SLUDGE FROM SAID SLUDGE SPACE, MEANS FOR INTERMITTENTLY OPENING THE SLUDGE DISCHARGE PORT MEANS, A PRESSURE SENSITIVE DEVICE IN THE OUTPUT OF THE CENTRIPETAL PUMP MEANS AND OPERATED BY THE PRESSURE IN THE OUTPUT, CONTROL MEANS FOR ACTUATING THE MEANS FOR OPENING THE SLUDGE DISCHARGE PORT MEANS INTERMITTENTLY, AND MEANS OPERATIVELY CONNECTING THE PRESSURE SENSITIVE DEVICE TO THE CONTROL MEANS.