US2286354A

US2286354A - Centrifugal separator

Info

Publication number: US2286354A
Application number: US318672A
Authority: US
Inventors: Harold C Fitzsimmons
Original assignee: Sharples Corp
Current assignee: Sharples Corp
Priority date: 1940-02-13
Filing date: 1940-02-13
Publication date: 1942-06-16
Anticipated expiration: 1959-06-16
Also published as: GB543508A; FR869873A; NL66060C

Description

June 16, 1942- H. c. Fl-rzslMMoNs CENTRIFUGAL SEPARATOR I5 Sheets-Shea*l l Filed Feb. 13, 194Q INVENTOR Harold C: it'smmons n. w. Ml-

l, wauw.. A

A TTORNEXv l June 16., 1942'. H. c. FrrzsiMMoNs CENTRIFUGAL SEPARATOR 5 Sheets-Sheet 2 INVEl-vTR;

H orold Ci; Ltsmmons BY QXCUMML Filed Feb. 13, 1940 i lll/111111 ATTORNEY June 15, 1942 H. c. FlTzslMMoNs CENTRIFUGAL SEPARATOR 5 Sheets-Sheet 3 Filed Feb. 13, 1940 INVENToR l Hrold @.Pc55immons ATTORNEY Vvat the Patented June 16, 1942 Harold C. Fitzsimmons.

Sharples Corporation,

signor to The West Chester, Pa., as-

Philadelphia, Pa., a corporation of Delaware Application February 13,

Claims.

. The present invention pertains to the art of centrifugal separators designed to effect separation of solids from a liquid, or separation of solids from a mixture of liquids. It pertains to the type ,of centrifugal inwhich solids are intermittently vdischarged through valve-controlled discharge passages in the wall of the centrifugal rotor.

The centrifugal of the invention incorporates a number of features which enable it to fulfill the separating function with maximum efficiency. In the first place, the Walls of the rotor are arranged at'a substantial angle with respect to the axis of the rotor in order tovfacilitate flow of deposited solids toward the orifices from which they are to be discharged. In the second place, the centrifugal rotor `is provided with superposed stratifying discs. In the third place, the means provided for actuating the valves are positive in their action, and delicately responsive to conditions within the rotor by which actuation of the valves is attained.

cess'ful arrangement has been to control the` operation of the valves by means of floats, whose operation was in turn responsive to the quantity of sludge deposited in the centrifugal rotor.

When the valves were actuated by floats reaching to the surface of the rotor liquid, the actuating means extended throughout the depth of liquid within the rotor. As a consequence of this fact, such machines were subject to certain seri-` ous limitations.

The valves and their actuating floats could not be located in a longitudinally central zone of the rotor provided with stratifying discs, since the actuating means extended to the inner surface of the liquid under treatment. It was therefore necessary to locate the floats which controlled the actuation of the valves toward the base of the rotor, beneath the discs.

The necessity of locating the floats and valves base of the rotor resulted in further limitations of design and efficiency.. In designing 'a rotor in which the valves were located at the base, and in which the inner circumferential wall of the rotor had a substantial angle of conicity, it was necessary that the rotor be of substantially larger maximum diameter than would be necessary for comparable centrifugal capacity and efficiency if the valves could be located longitudinally centrally of the rotor, and the rotor be de-l signed in such a way that the maximum diameter was in this central zone. These factors imposed acters, the rotor of the =sages controlled by 1940, serial No.,s1s,s1z

serious limitations on the structure of the rotor and on themaximum speed at which 'it could be operated, in view of the stresses imposed by operation at high speeds.

An object of the provide a centrifugal rotor having discharge pasvalves, in which the above limitations are avoided. This object has been attained by providing valve actuating lmeans which are extremely compact and which are located in the part of the centrifugal rotor between the outer edges of the discs and the inner circumferential wall of the rotor. These actuating means are positively operated by fluid pressure.

Another object of the invention has been to avoid contamination of discharged solids with discharged actuating liquid. This object is attained by providing a .construction in which there are separate outlets for the actuating liquid.

A still further object of the invention has been to provide a machine of this type. in which abrasion'of the parts against which the solids impinge upon discharge from the rotor is avoided.

Still further objects of the invention will be obvious upon reading cation in the light of the attached drawings, in which,

Figure 1 is a central axial section through half of av centrifugal rotor embodying the principles -of the invention.

Figure 2 is a detailed View, partly in section and partly in elevation, illustrating one of the valve actuating units of the inventionl Figure 3 is a detailed cross section, illustrating connections for permitting escape of valve actuating liquid,

Figure 4 is a view, partly in section and partly in elevation, illustratingh a detail of the conduit connections by .whieh one of the valve actuating units is controlled,

Figure 5 is a detailed vcross section illustrating an alternative form. of valve actuating unit, and

Figure 6 is a view, partly in cross section and partly in elevation, illustrating details of the casing which receives the discharged centrifugal effluents.

Attention is called to the fact that Figure 1 of the drawings illustrates only the left left-hand side of the centrifugal rotor, and that the line AA represents the axial center line of the rotor.

Referring to the drawings by reference charinvention is driven by a shaft il) mounted for rotation within a support il, and driven by any suitable form of motor, not shown. A sleeve l2 surrounds the shaft lll and is driven by this shaft through driving connections of conventional design. The main body portion i3 of the rotor maybe secured to the sleeve i2 in any conventional manner, such as by the screw threaded connection I4. A feed tube present invention has been to4 of the sub-joined speci- I5 surrounds the sleeve I2, and serves to direct The solids in the liquid fed to the rotor pass outwardly to the peripheral wall of the rotor and the heavier liquid also passes outwardly toward the peripheral wall, and forms a stratum within the deposited solids. This liquid passes inwardly through the space between a dividing wall I9 toward the upper end of the rotor, and the upper portion 20 of the rotor, which may be secured to the main body of the rotor by the screw threaded connection 2 I. This heavier constituent passes outwardly from the rotor across the ring dam 22. The -lighter liquid passes inwardly through the spaces between the superposed discs I8 into a space 23 within the disc-block, and upwardly through the space'24 between a tubular extension 25 of the Idividing wall, and feed tube I5. 'I'he liquid centrifugal effluents discharged over ring dam 22 and from tube 25 are collected in separate centrifugal covers 6I and 62 (Fig. 6).

The inner peripheral wall of the main body of the rotor consists of opposed frusto-

conical surfaces

26 and 21, and the point of maximum diameter of the main body of the rotor is located approximately centrally of this portion of the rotor.

The features` of the present invention pertain to the novel mechanism employed to effect intermittent discharge of the deposited solids, and are not dependent upon the particular features of feed of the mixture to the rotor or of discharge of the subsided liquid constituents separately from the rotor. 'I'he present invention may be employed in connection with a centrifugal rotor of the so-called clarifler type, in which a solid constituent is separated from only a single liquid,

' or it may even be employed in connection with a machine designed to separate three or more immiscible liquids from each other during intermittent discharge of separated solids.

It will be seen that, when a mixture of liquids and a solid is introduced into the tube I5, and the centrifugal rotor is' rotated at high speed during the continuous feed of the mixture, the solids will be deposited along the surfaces 26 and 2Tand flow outwardly along these surfaces to the zone 28, while the liquids are separated and separately discharged from the rotor as indicated above.v The rotor is provided with a plurality of small passages 29 through which these solids are intermittently discharged. These passages may be provided with bushings 30, radially extending valve guide members 3| (Fig. 2), and valve seats 32, as illustrated. A reciprocating valve 33 is provided for coaction with each of the valve seats 32,'and each of these valves 33 is connected with a valve stem 34, which is actuated by means to be described hereinafter for intermittent discharge of deposited solids through thevalve seats 32 and bushings'30.

The novel features of the invention pertain principally to the mechanism by which the valve stems 34 are. operated to break the contact between the valves 33 and valve seats 32 intermittently, in response to the accumulation of sludge in the space 28. In the form of the invention illustrated in Figures 1 to 3 of the drawings, a plurality of iiuid pressure motors 35 fulfill this function, an lindividual motor being attached to each of the individual valve stems 34.

.As illustrated in Figures 1 to 3, each of these motors comprises a housing which consists of an end portion 36 and a base portion 31 secured to the portion 36. This housing surrounds the moving parts of the motor. The base portion 31 terminates in an annular extension 38 (see Fig. 2) which lies adjacent the zone 28 of accumulation of solids. The inner end 39 of the valve stem 34 has a cover 4I which is the moving inember of the v4iiuid pressure motor. In the form of the invention illustrated in Figure 1, the Amotor includes a Sylphon 40, having a portion secured to the inner end of the valve stem. The inner end ofthe cover 4I of the valve stem has a cap 42 which reciprocates within a cylindrical bore 43 in the housing member 36 to assist in guiding the valve stem in its reciprocating movements. An annular base member 44 is secured to the end of the Sylphon opposite to the cover 4I, and this base portion 44 is held against a iiange 45 of the skirt member 31.

A bracket 46 is secured to the housing base 31 and this bracket member is also secured to the rotor wall, thereby holding the iiuid pressure motor assembly in position. The housing base 31 is also provided with a lateral extension 55 through which liquid is passed from the main body of thece'ntrifugal rotor for actuating the iiuid pressure motor. 38 and 55 is connected with a bore 48, which is in turn connected with a conduit 49. Theconduit 49 extends downwardly and inwardly around the lower end of the disc-bloc, and is connected lat its inner end to member 50, which has a bore 5I (see Fig. 4) registering with the conduit 49,

and a channel 52 communicating with the inner end of said with the channel 52, and is connected to a second, and smaller conduit 54, which extends outwardly from the member 50 to a connection in the lateral extension 55 of the housing base 31. This conduit 'communicates with a, bore 56 in the extension 55, which in turn communicates with an annular channel' 51 in the outer wall of the base member 44 of the Sylphon 40, and with the space between the Sylphon 4 6 and the inner wall of the housing end portion 36. The base flange of the base member 45 is provided with an orifice 58 an outlet 60 (see Fig. 3), throughv which liquid 'passing through4 to the space between the Sylcharged through the valve 32, and this material is collected separately from the solids.

In the operation of the machine described above, when the machine is rst brought up to speed, the valve 33 is forced against the valve seat. 32 under the inuence of the centrifugal force operative upon the 4valve stem 34 and the parts of the Sylphon. As the rotor fills with liquid, a part of this liquid enters the space'between the extension 38 and the v alve stem 34, and the pressure applied to this liquid by reason of the rotation of the main body of liquid within the rotor forces the valve stem 34 to move in- An inlet 41 in extensions bore. A bore 53 als' communicatesf communicating with a bore 59 andv 89 and 8d, p

-- parent.

wardly and remove the valve d@ from the valve seat s2. As the body of liquid in the rotor becomes deeper, liquid entering between the parts fo through bores di and e8, enters conduit de and passes inwardly through this conduit. e inner end oi` the bore Si in the member @d is slightly further 'removed from the rotor anis i the inner edge of the ring dam-22. Accorinsly. when the liquid reaches of the rotor to cause the heavier liquid to be discharged over ring dam 22, the liquid entering the conduit d@ and bore El will overdow the inner end of the bore i. and enter the bore es. The liquid entering the bore d3 flows outwardly through tube te into bore 5% and the space between the inner wall of the housing end portion 3d the pressure in this space, due to the head of liquid in conduit et, increases. this pressure becomes sumciently great to actuate the Sylphon to cause the valve to be forced against its seatagain. After this occurs, the valve will be retained against its seat, until it is forced away from that seat in response to factors automatically resulting from accumulation of sludge in the space 2d. During the part of the cycle of operations when liquid is flowing from bore 5l into bore 53 the quantity of liquid passed into bore E@ is more than sumcient to oiset the amount of leakage through orifice te and from the rotor through outlet ed.

After the valves 33 are moved into closed position as discussed above, solids-accumulate within the space 2s during the continued feed of material to the rotor and rotation thereof, and these solids form a wall gradually approaches the extension 38 of the housing base portion 3l. As the accumulation of solids increases, the resistance to flow of liquid into the interior of the housing base portion 3l between the inner surface of the accumulated solids and the base 88 of the skirt also increases, until the flow resistance becomes suiiiciently great to offset the difference in hydrostatic balance between the inner edge of the ring dam 22 and the inner end of the bore 5l. When this condition occurs, liquid will no longer flow into the channel 62 and bore 58 from the bore 6I, and leakage of liquid through orifice 58 causes diminution of the pressure against the upper end of the valve stem tending to retain the valve 33 against its seat 32. The pressure of liquid against .the lower side ofthe upper end 39 .of the valve stem 3d then causes the Sylphon to expand and draw the valve 33 away from its seat 32, thereby permitting discharge of accumulated solids through passage 2s.

As the solids discharge, the wall of solids recedes from the base 38 of the housing base portion 3l, and the .hydrostatic pressure operative through the space between the bed of solids and the extension 38, the conduit 48, and associated connections gradually increases until liquid a sufdcient depth is again forced into channel 52 and through conduit 54 into the space within the housing end portion 3s. After liquid has been introduced into conduit 69 to produce sufficient liquid head in the conduit 58, the valve will again be closed and the cycle of operations may be repeated indefinitely.

The manner in which the principal objects of the invention have been attained will now be ap- By providing a valve actuating unit operating under fluid pressure, as described above? the valve actuating unit may be extremely and the Sylphon di). As

within the space 28 which co pact, and may lie far beneath the surface of liquid in the centrifugal rotor. This makes it possible to locate the valve actuating unit entirely outside the outer edges el of the discs, and obviates the necessity of locating the valve actuating means at the base of the rotor. A nest of discs extending substantially throughout the length -of the rotory may therefore be employed, and the valve lactuating mechanism may be located centrally of the longitudinal extent of the outer edge of the disc-block. Asaconsequence of this fact, a. rotor tapering in opposite directions toward the zone of solids discharge may be employed. and the rotor may have a substantial angle of conicity to facilitateflow of solids in opposite directions toward the solids discharge point without thenecessity of employing a rotor of such large maximum diameter at the zone of solids discharge as to impose the limitations discussed in the introductory remarks of the present application.

While, in the embodiment of the invention ilvlustrated in Figures land 2 of the drawings, the actuating motor.. for the valves have been illustrated as mounted with their axes in a radial plane with respect to the rotor, it will be understod that this radial mounting of the hydraulic motor is not an essential feature of the invention. These actuating means can be mounted with their axes inV any desired plane, provided suitable gear or lever actuating mechanism is provided for moving the valves to and from the valve seats.

The features of the invention by which abrasion of the parts against which the solids impinge upon discharge from the rotor is avoided are illustrated in Figure 6 of' the drawings. The casing surrounding the centrifugal rotor includes covers 6i and 62 for receiving the liquid effluents from the rotor, and a lower cover 63, connected to a discharge chute 6d, lfor receiving the solids discharged through passages 29, and directing them to a suitable receptacle.

Solids separated from liquids in a machine of this kind are frequently of a highly abrasive character. 'I'hese solids are discharged at high velocity under the iniiuence of centrifugal force, and difdculty of abrasion of the cover which receives the discharged solids is therefore frequently encountered, unless special means are provided to avoid such abrasion. A feature of the present invention consists in the provision oi means for retarding the discharged solids before they impinge against any permanent part of the centrifugal frame. The means employed for retarding vthe solids are detachably secured within the frame of the machine and are relatively light and inexpensive. As a consequence of these facts, these means may be cheaply replaced when some other suitable composition capable of resisting abrasion, thereby prolonging the life of these rings. The solids discharged through the passages 29 travel 1in a direction which is substantially tangential to the outer circumference of the rotor, as they leave the rotor. These solids impinge against the inner surface of the ring 64,

' and they are substantially decelerated by"im pinging against the inner surface of the ring during their passage about part of the inner circum ference of the ring, before being discharged against the inner surface of the cover 63. By reason of this fact, the velocity of the solids has been sufficiently retarded before they impinge against the cover 63 to prevent destructive abrasion of the cover itself.

Figure 5 illustrates a modification of the invention involving substitution of hydraulic motors of the piston and cylinder type for the hydraulic motors 35. The'motor of Figure 5 may be secured to the centrifugal rotor in the same manner as the motors of Figures 1, 2 and 3, and may be provided with similar hydraulic connections, such as those designated by the reference numerals 41 to 60 of Figures 1 to 3 of the drawings. The cylinder 10.may be clamped in place between the motor housing 1| and skirt 12. A reciprocating piston 13 operates within the cylinder 1D, and this piston is in turn secured by means of piston rod 14 to the valves which control discharge'of deposited solids from the rotor, as illustrated and described in connection with Figures 1 to 3 of the drawings. Liquid entering the cylinder 10 outwardly of the piston 13 causes that piston to move inwardly, and liquid passed to the portion of the housing 1l surrounding the cylinder and piston assembly causes it to move outwardly. The accumulation ofsludge beneath the annular portion 15 operates to impede ingress of liquid into the connections 41 to 56, and thereby di- .minishes the pressure operative to hold the valves in closed position, thereby permitting the valves to be opened by the pressure imposed on the outer side of (beneath) the piston 13.

In case one or more of the valves 33 becomes stuck in closed position, or in case it is found that the valves remain in closed position for a longer period than desired in the treatment of a particular material, the operator may cause these 'valves to be opened by interrupting feed of the i liquid to the machine until the level of liquid in the rotor recedes to a point-at which liquid no longer passes through bores 5I and channels 52 to channels 53 and conduitsl 54. This interruption of passage of liquid into the conduits 54 operates to cause the valves to open, in the same Way as does accumulation of solids adjacent to annular portion 3B of the skirt 31. The machine may be provided with suitable timing connections to cause interruption of feed at fixed intervals to effect this result, if desired.

As a still `further alternative, the entire centrifugal may be mounted on a weighing device provided with an automatic arrangement whereby the feed of liquid to the rotor is interrupted in case the weight of the rotor and contents exceeds a predetermined limit. Thus, in case the solids soft or slimy character that they fail to block the flow `of liquid to the valve control conduits l until the weight is decreased to a point at which the feed is again automa ically resumed.

As a still further alternative, the hydraulic motors which control the discharge of solids may be actuated by liquid which is entirely separate from the liquid operated upon within the rotor.

to be discharged from the rotor are of such a Thus, liquid from an external source of supply may be introduced to the hydraulic motors from a zone which is radially within these motors, in order to retain the valves in closed position. When it is desired to open the valves, the feed of such auxiliary liquid may be discontinued, thereby permitting escape of this actuating liquid and opening of the valves. The feed of auxiliary liquid employed to retain the valves in closed position may be automatically controlled to cause opening and closing of the valves at fixed intervals, or in response to the accumulation of a given amount of solids within the centrifugal rotor.

Still further modifications will be obvious to those skilled in the art, and I do not therefore Wish to be limited except by the scope of the subjoined claims.`

I claim: v

1. In a centrifugal separator. the combination comprising a centrifugal rotor for effecting centrifugalsedimentation of solids from a mixture thereof with liquid, a discharge passage in the wa11.of said rotor, a valve controlling the flow through said discharge passage, a fluid pressure motor connected to said valve for operating said valve, means establishing communication between said fluid pressure motor and the separating space of said rotor for actuation of said fluid pressure motor in one direction, means establish ing communication between another part of said fluid pressure motor and-the separating space of said rotor for actuating the fluid pressure motor in the direction opposite to said first-mentioned direction, and means responsive to conditions in said rotor for restricting flow of liquid from the separating space of said rotor through one of said communication establishing means, whereby to effect actuation of said motor and movement of said valve.

2. In a centrifugal separator, the combination comprising a centrifugal rotor for effecting centrifugal sedimentation of solids from a mixture thereof with liquid, a discharge passage in the wall of said rotor, a valve controlling the flow through said discharge passage, a fluid pressure motor connected to said valve for operating said valve, means establishing communication betweensaid fluid pressure motor and the separating' space of said rotor for actuation of said fluid pressure motory in one direction, means establishing communication between another part of said fluid pressure motor and the separating space of'l said rotor for actuating the fluid pressure motor in the direction opposite to said firstmentioned direction, and means responsive to accumulation of solids in said rotor for restricting flow of liquid from the separating space of said rotor through one of said communication establishing means, whereby to effect actuation of said motor andvmovement of said valve.

Y 3. In a centrifugal separator, the combination comprising a centrifugal rotor for effecting centrifugal sedimentation of solids from a mixture thereof with liquid, a discharge passage in the wall of said rotor, a valve controlling the flow through said discharge passage, a fluid pressure motor including a Sylphon connected to said valve for operating said valve. means establishing communication between said uid pressure motor and the separating space of said rotor for actuation of said fluid pressure motor in one direction, means establishing communication between another part of said fluid pressure motor and the separating space of said rotor for actuating the fluid pressure motor ln the direction opposite to said first-mentioneddirection, and means responsive to'conditions in said rotor for restricting flow of liquid from the separating space of said rotor through one of said communication establishing means, whereby to efi'ect actuation of said motor and movement ofmotor connected to said valve for operating said valve,v means establishing communication between said iiuid pressure motor and the separating space of said rotor for actuation ofsaid iluid pressure m'otor in one direction, means establishing communication between another part of said fluid pressure motor and the separating space of said rotor for actuating the fluid pressure motor in the direction opposite to said first-mentioned direction, means permitting leakage of liquid from said last-mentioned communication establishing means to the exterior of the rotor and meansresponsive to conditions in said rotor for restricting ow of liquid from the separating space of said rotor through said lastmentioned communication establishing means, whereby to eect actuation of said motor and 4 movement of said valve.

5. In a centrifugal separator, the combination comprising a centrifugal rotor for effecting centrifugal sedimentation of solids from a mixture .thereof with liquid, a discharge passage in the wall of said rotor, a valve controlling the flow of liquidthrough said discharge passage, a fluid pressure motor connected to said valve. for operating said valve, a conduit extending inwardly from a space of said rotor occupied by liquid during normal operation, a second conduit connected to the' inner end of the first conduit and also connected to said fluid pressure motor in such relationship as to operate said motor upon passage of liquid from said rst conduit into said second conduit and from said said motor. and means responsive to conditions in saidv rotor for restricting flow of liquid from the separating space of said rotor through said firstmentioned conduit into said second-mentioned conduit.

6. In a centrifugal separator, the combination comprising a centrifugal rotor for effecting centrifugal sedimentation of solids from a mixture thereof with liquid, a discharge passage in the wall of said rotor, a valve controlling the flow of liquid through said discharge passage, a fluid pressure motor connected to said valve for operating said valve, a. conduit extending inwardly from a space of said rotor occupied by liquid during normal operation, a second conduit connected to the inner end of the first conduit and also connected to said fluid pressure motor in such relationship as to operate said motor upon passage of liquid from said first conduit into said second conduit and from said second conduit to said motor. means responsive to conditions in said rotor for restricting flow of liquid from the separating space of said rotor through said firstmentioned conduit into said second-mentioned conduit. and means directing leakage of a part of the liquid passed through said second-mentioned conduit toward said fluid pressure motor to the exterior of the centrifugal rotor.

vnected to theinner end 7. In a centrifugal separator, the combination comprising a centrifugal rotor for effecting centrifugal sedimentation of solids from a mixture thereof with liquid, a discharge passage in the wall of said rotor, a valve controlling the flow oi liquid through said discharge passage, a uid pressure motor connectedto said valve for oper- .ating said valve, a conduit extending inwardly from a space of said rotor occupied by liquid during normal operation, a second conduit conof the first conduit and also connected to said Afluid pressure motor in such relationship as to operate said motor upon passage of liquid from said rst conduit into said second conduit and from said second conduit to said motor. means responsive to conditions in said rotor for restricting flow of liquid from the separating space of said rotor through said firstmentioned conduit into said second-mentioned conduit, and means establishing communication between the separating space of said rotorand another part of said fluid pressure motor for actuating said fluid pressure motor in a direction opposite to the direction in which said uid pres sure motor is actuated by liquid passing through said last-mentioned conduit.

8. In a centrifugal separator, the combination comprising a centrifugal rotor having inner peripheral walls consisting of opposed tapering surbeyond said discharge passage, the outer circumvd5 second conduit to faces for effecting centrifugal sedimentation of solidsfrom a mixture thereof with liquid, a discharge passage in the peripheral wall of said rotor in the zone of intersection of said surfaces,

a valve co-acting with said discharge passage,

a valve extension connected to said valve and extending inwardly into said rotor, a plurality of substantially parallel stratifying discs in said rotor extending 'in both directionslongitudinally ferences of said discs and the peripheral walls of said rotor defining a relatively free liquid space within said rotor, fluid pressure actuated means within the liquid space' of said rotor and lying between the outer circumferences of said discs and the inside liquid contact surface, of the peripheral'wall of the sedimentation chamber of said rotor interconnected with said valve extension for actuation of said valve, and means for supplying fluid under pressure to said fluid pressure actuated means valve.

9. In a centrifugal separator, the combination comprising a centrifugal rotor having inner peripheral walls consisting of opposed tapering surfaces for eecting centrifugal sedimentation of solids from a mixture thereof with liquid, a discharge passage in the' peripheralwall of said rotor in the zone of intersection of said surfaces, a valve co-acting with said discharge passage, a valve extension connected to said valve and extending inwardly into said rotor, a plurality of substantially parallel stratifying discs in said rotor extending in both directions longitudinally beyond said discharge passage, the outer circumferences of said discs and the peripheral walls of said rotor defining a relatively free liquid space within said rotor, aI reciprocating fluid pressure motor within the liquid space of said rotor and lying between the outer circumferences to effect actuation of said fluid pressure motor to effect actuation of said valve.

10. In a centrifugal separator, the combination' comprising a centrifugal rotor having inner peripheral walls consisting of opposed tapering surfaces for effecting centrifugal sedimentation of solids from a mixture thereof with liquid, a discharge passage in the peripheral wall of said rotor in the zone of intersection of said surfaces, a valve co-acting with said discharge passage, a valve extension connected to said valve and extending inwardly into said rotor, a plurality of substantially parallel stratifying discs in said rotor extending in both directions longitudinally beyond said discharge passage, the outer circumferences of said discs and the peripheral walls of said rotor defining a relatively free liquid space within said rotor, a Sylphon within the liquid space of said rotor and lying between the outer circumferences of said discs and the inside liquid contact surface of the peripheral wall of the sedimentation chamber of said rotor interconnected with said valve extension for actuation of said valve, and means for supplying fluid under pressure to said Sylphon to effect actuation of said valve.

11. In a centrifugal separator, the combination comprising a centrifugal rotor having inner peripheral walls consisting of opposed tapering surfaces for effecting centrifugal sedimentation of solids from a mixture thereof with liquid, a discharge passage in the peripheral wall of said rotor in the zone of intersection of said surfaces, avalve co-acting lwith said discharge passage, a valve extension connected to said valve and extending inwardly into said rotor, a plurality of substantially parallel stratifying discs in said rotor extending in both directions longitudinally beyond said discharge passage,A the outer circumferences of said discs and the peripheral walls of said rotor defining a relatively free liquid space within said rotor, fluid pressure actuated means'within the liquid space of said rotor and lying between the outer circumferences of said discs and the inside liquid contact surface of the peripheral wall of the sedimentation chamber of said rotor interconnected with said valve extension for actuation of said valve, and means for passing a part of the liquid from the separating space Within said rotor to said fluid actuated means to control the operation thereof.

12. In a centrifugal separator, the combination comprising a centrifugal rotor having inner peripheral walls consisting of opposed tapering surfaces for effecting centrifugal sedimentation of solids from a mixture thereof with liquid, a discharge passage in the peripheral wall of said rotor in the z one of intersection of said surfaces, a valve co-acting with said discharge passage, a valve extension connected to said valve and extending inwardly into said rotor, a plurality of substantially parallel stratifying discs in said rotor extending tion of said valve, means for passing a part of the liquid from the separating space within said rotor to said fluid actuated means to control the operation thereof, and means for directing leakage of a part of said liquid passed to said fluid actuated means from said rotor at a different discharge point from the point of discharge of solids through said passage.

13. In a centrifugal separator, the combination comprising a centrifugal rotor having inner peripheral walls consisting of opposed tapering surfaces for effecting centrifugal sedimentation of solids from a mixture thereof with liquid, a discharge passage in the peripheral wall of said rotor in the zone of intersection of said surfaces, a valve coacting with said discharge passage, a valve extension connected to said valve and extending inwardly into said rotor, a plurality of substantially parallel stratifying discs in said rotor extending in both directions longitudinally beyond said discharge passage, the outer circumferences of said discs and the peripheral Walls of saidl rotor defining a relatively free liquid space within said rotor, fluid pressure actuated means within the liquid space of said rotor and lying between the outer circumferences of said discs and the inside liquid contact surface of the peripheral wall of the sedimentation chamber of said rotor interconnected with said valve extension for actuation of said valve, and means responsive to accumulation of sludge adjacent said valves for supplying fluid under pressure to said fluid pressure actuated means to effect actuation of said valve.

14. In a centrifugal separator, the combination comprising a centrifugal rotor having inner peripheral walls consisting of opposed tapering surfaces for effecting centrifugal sedimentation of solids from a mixture thereof with liquid, a

,discharge passage in the peripheral wall of said rotor in the zone of intersection of said surfaces, a valve engaging said discharge passage, a valve stem connected to said valve and extending inwardly into said rotor, a plurality of substantially parallel stratifying discs in said rotor extending in both directions longitudinally beyond said discharge passage, the outer circumferences of said discs and the peripheral walls of said rotor defining a relatively free liquid space within said rotor, a valve actuating motor including means for positively actuating said valve in opposite directions mounted within the liquid space of said rotor and lying between the outer circumferences of said discs and the liquid contact sur face of the peripheral wall of the separating chamber of said rotor, said motor being interconnected with said valve stem for actuation of f said valve, and means responsive to variation of sludge within said rotor for controlling the operation of said motor to move said valve to open and closed positions, respectively.

15. In'a oentrifugalbowl; means forming an opening in the bowl wall for the discharge of sludge therefrom, a member` movable within said bowl to open and close said opening, means forming with said member a chamber, said member being operated by pressure within said chamber, a restricted discharge opening from said chamber to the exterior of said centrifuge bowl, and a channel connecting said chamber with the sludge space .of said bowl.

HAROLD C. FITZSIMMONS.