US3095371A

US3095371A - Centrifuge having gas vent

Info

Publication number: US3095371A
Application number: US117578A
Authority: US
Inventors: Harold C Fitzsimmons
Original assignee: Sharples Corp
Current assignee: Sharples Corp
Priority date: 1961-06-16
Filing date: 1961-06-16
Publication date: 1963-06-25
Anticipated expiration: 1980-06-25

Description

June 1963 H. c. FITZISIMMONS 3,095,371

CENTRIFUGE mwms GAS VENT Filed June 16. 1961 46 INVENTOR.

HAROLD c. FITZSIMMONS BY [W ATTORNEY United States Patent 3,095,371 CENTRIFUGE HAVING GAS VENT Harold C. Fi'tzsimmon's, West Chester, Pa., assignor to The Sharpl es Corporation, a corporation of Delaware FiledJun'e 16, 1961, Ser. No. 117,578 3 Claims. (Cl. 233-45) This invention relates generally to centrifuges for separating materials of different densities such as centrifugal separators and centrifugal c-larifiers, and more particularly this invention relates to centrifuges in which the materials to be separated or clarified are introduced or fed into the rotating rotor or bowl of the centrifuges under pressure.

The liquid materials fed to centrifuges for separation or clarification frequently are accompanied by substantial quantities of gas or vapor, hereinafter for convenience referred to collectively as gas. The gas may be coarsely or finely dispersed inthe flowing liquid or there may be an alternate flow of what are commonly referred to as slugs of liquid separated by gas.-

The gas may he air which has been entrained in the liquid to be centrifuged by agitating in an open container prior to pumping it to a centrifuge. For example, in the refining of vegetable oil to wash soap out of the oil, the oil may be agitated with water in an open tank. The soap dissolves in the water, and the mixture is passed to a centrifuge to separate the oil freed of its soap and the soapy water. Agitation which is suificient to result in a satisfactory transfer of the soap from the oil to the water results in anoccl'usion of air in the mixture which is carried on to the centrifuge.

As another illustration, the gas may be the result of a reaction between constituents of the liquid material to be centrifuged; For example,- crude vegetable oil containing fatty acids may be treated with a solution of sodium carbonate for neutralization of the acids. The sodium carbonate reacts with the fatty acids forming soaps and liberating carbon dioxide. The mixture containing dispersed gaseous carbon dioxide and insoluble soap, is fed to a centrifuge" to separate the soap from the neutralized oili Frequently a liquid mixture to be separated is heated, for instance to reduce its viscosity to facilitate separation, such as by heated surfaces or by the introduction of vapors as it is passedto a centrifuge, with the result thatthe liquid contains free vapor, that is gas when it enters the centrifuge.

On the other hand, a leaky stufling box or pipe connection on the inlet side of a pump used for feeding a liquid mixture to a centrifuge may allow air to leak into the mixture fed to the centrifuge. Air may also leak into the bowl feed around the rotary seal at the base of the bowl spindle through which feed liquid passes from a stationary supply pipe to the rotating spindle.

Then too, the gas the mixture fed to the centrifuge may be the result of incomplete solution or incomplete reaction of a gaseous reagent admixed with a feed to the centrifuge as,- for instance, in case of" the addition of gaseous ammonia to neutralize, and form insoluble soaps with, the fatty acids contained in vegetable oil.

Even though the liquid to be centrifuged contains no gas, conduits leadingfrom the supply of liquid to be centrifilged may be full of gas which is displaced bythe initial how of liquid and is conducted to the centrifuge.

Irrespective of the origin of gas which occurs with the liquid fed to a centrifuge, or the nature of such gas, when such mixturesare fed to a centrifuge under pressure with sealed feeding connections, such as a centrifuge of the full bowl type, the gas is forced into the bowl of the centrifuge. As will be seen from a study of the details of the design of such a centrifuge hereinafter described, gas introduced with the liquid feed accumulates in. thebowl of the centrifuge; greatly interfering with its effectiveness as a separator or clarifier, and greatly increasing the amount of pressure requiredto; force the liquid tobe centrifuged through the centrifuge, unless provisions are made for the release from thebowl of such gas.

In the case of cream separators of the full bowl type, there has been a ready solution. A passage. has been provided connecting. allparts of the center of the bowl so that any gas entering thebowl may pass from one com.- partment to another, and out of the bowl with the separated cream. However, such a passageway, if. large enough to satisfactorily relieveany accumulation of gas, also permits the passage of unseparated liquid entering the centrifuge bowl. which becomes mixed with the dis charging cream. This can be tolerated in the case of: cream separation since cream is merely a concentration of butterfat particles: in milk serum,.and aminor dilution. of concentrated cream. with: the whole milk fed to the centrifuge can be compensated for by effecting somewhat higher concentration of cream in the main separating compartment of the bowl.

The above-mentioned passageway is not a solution to the problem when the full. bowl type of centrifuge with sealed feed is used in separations where. it is desired to have the lighter component of the mixture discharged from the bow-l unpoluted by the feed to the bowl, as, for: instance, in the separation of oil from water containing dissolve-d soap, or in the separationof oil from soapstock, as has been referred to above, or in the separation of' neat soap from nigre in the manufacture of soap. In such cases the passageway in the center of the bowl for the release of gas would allow the. pollution of the separated lighter liquid component of the mixture 'with gas and liquid of thefeed which has not passed through the. effective separating devices of the bowl.

The pollution of the separated lighter liquid componentis exceptionally objectionable in the case of the separation of neat soap from nigre'. In that case the shearing of the air and neat soap mixture, which occurs as the mixture passes from the rapidly rotating bowl to the stationary receiver, results in a very fine dispersion of the air in the neat soap. This air can only be separated from the neat soap by very prolonged settling at high temperature.

To resolve this problem, a prior patent presents means for disposing of gas accumulating in the feed distribution chamber of a centrifuge. It. presents a vent line means connecting the upper central portion of the chamher and extending axially down the spindle to a point below the bowl and turning radially of the spindle to terminate in an opening to the atmosphere. To avoid loss of liquid as-well as gas, special valve means were contemplated. In one embodiment, for instance, the vent line means terminated in the feed distribution chamber in an outwardly facing annular valve seat positioned about the axis of the bowl. A conventional O-ring surrounded this seat and served as a valve body, expanding outwardaway from the seat by centrifugal force in the absence of liquid to permit gas to vent off through the seat, and floated inwardly by the liquid, after the gas vent off, to close the valve.

I have developed a centrifuge bowl having an improved gas vent valve which offers great flexibility of design. It comprises. a valve body being free for movement bodily to a valve seat and away from the seat to an outer limit. It is especially sensitive to the buoying pressure of liquid closing inwardly of the bowl. In the absence of liquid it moves freely outward from the center of the bowl under centrifugalforce.

Further features of the invention will become apparent to persons skilled in the art as the specification proceeds and upon reference to the drawings in which:

FIGURE 1 is an elevation, partly in section, illustrating one form of the invention;

FIGURE 2 is an enlarged fragmentary sectional view taken on the line 22 of FIGURE 1;

FIGURE 3 is an enlarged perspective view of a valve body as used under one form of the invention; and

FIGURE 4 is a fragmentary sectional elevation of another form of the invention.

Briefly, in combination with a centrifuge bowl having feed means and discharge means, my invention comprises vent line means extending from a central portion of the inside of the bowl to the outside of the bowl in the vent line means, a valve seat, and a rigid buoyant valve body adapted to engage against the seat to close the vent line means. The body is free for movement toward and away from the seat, and is normally held against the seat by centrifugal pressure of liquid in the rotating bowl, but is thrown away from the seat by centrifugal force in the absence of such pressure.

Referring now to FIGURE 1, the lower part of a centrifugal separator bowl, together with associated parts, is shown in section. The bowl shell is surmounted by a bowl top 11 which is held on to the bowl shell 10 by the coupling ring 12 threadedly connected to the bowl shell 10. The bowl shell 10' is mounted on the bowl spindle 13 and held in place thereon by the nut or cap 14 which is threadedly connected to the bowl spindle 13. The bowl spindle 13 is mounted in a conventional manner for the rotation of the bowl and the bowl spindle. The disc stack support 15 rests on the bottom of the bowl shell 10 and is held in contact therewith by engagement with the bowl top (not shown). The disc stack support 15 is held in concentric relationship to the bowl shell 10 by means well known in the art.

A disc stack 16 which is shown for convenience as of a conventional type, is located in the main separating chamber 17 of the bowl between the disc stack support 15 and the bowl top (not shown). The vertical spacing of the disc is accomplished by any suitable means such as by means of spacers fastened to the upper surfaces of the discs to form thin separating spaces between the discs.

The bowl is mounted to rotate within a frame (not shown) to which it attached a cover. The cover in turn supports an assembly of parts for collecting the separated products discharging from the bowl, for example, as shown in FIGURE 5 of US. Patent 2,717,119, dated September 6, 1955.

The bowl spindle 13 is tubular and has a concentric channel 20 throughout its length. The lower end of the bowl spindle 13 is adapted to rotate in well-known sealing means between it and a stationary conduit by which the materials to be separated are fed to the centrifuge, a preferred form of which is shown in FIGURE 6 of said U.S. Patent 2,717,119. The nut or cap 14 is provided with at least one radial hole 21 communicating with the channel 20 in the spindle and also with feed distribution chamber 22 located between the bottom of the bowl shell 10 and the conical skirt of the disc stack support 15. Integral or associated with the conical skirt of the disc stack support 15 are a number of accelerating radial wings (not shown).

Each of the discs of the disc stack '16 is provided with a plurality of circumferentially spaced holes 24 positioned between its inner and outer edges, and these holes are arranged one above the other in the disc stack 16 to form vertical channels (only one being shown) extending through the vertical length of the disc stack 16. The conical skirt of the disc stack support 15 is provided with a number of passages 25, each passage 25 communicating at one end with the feed distribution chamber 22 and at the other end with a separate vertical channel.

A preferred embodiment of the invention is disclosed in FIGURE 2. As shown, vent line means extends from an upper central portion of the feed distribution chamber to the outside of the bowl, and comprises a cylindrical chamber 32 in cap 14 disposed transverse to the axis of the bowl. As shown, chamber 32 extends inward from one side of the cap to well past the axis of the bowl, terminating inwardly in an inner end 34. Adjacent the open or outer end the chamber is formed with an annular groove receiving a snap ring 36. The vent line means 30 further comprises a passage 38 extending from the center of the inner end 34 at which juncture is presented a valve seat 40, to an annular channel 42 about the lower face of cap 14.

Spaced outwardly from the axis of the bowl a distance equal to the radius of channel 42 is an opening 44 in the upper face of the bowl shell hub. From opening 44 downwardly to the outside of the bowl extends passage 46. On either side of opening 44 in the upper face of the bowl shell hub are grooves receiving O-ring seals 48 adapted to prevent leakage of gas or other fluid at the juncture of

passages

38 and 46.

'It is obvious from the above-described construction that if in assembly cap 14 is screwed home against the wheel bowl hub and the

passages

38 and 46 do not align radially, they will still freely communicate through the annular channel 42.

Disposed in the cylindrical chamber 32 is the valve body 50. In its preferred form it is an elongated cylindrical body which is rigid and hollow for reasons which will appear. FIGURE 3 shows that the inner end of the body, the seating end 52 is pointed, and the body is formed with a plurality of circumferentially spaced radially extending fins 54. The working or outer end 56 is flat and circular.

In the preferred form of the invention as shown in FIGURE 2 the valve body 50 is received within cylindrical chamber 32 and is only slightly shorter than the distance between snap ring 36 and the seat 40. The distance between distal edges of diametrically opposite fins 54 is slightly less than the diameter of chamber 32. In assembly the proportion of the valve body 50 is such that its center of mass is always disposed on one side of the axis of the bowl irrespective of the position of the body 50 in chamber 32.

From adjacent seat 40 a drain passage 58 connects the inner end 34 with the top surface of the cap 14 and slopes outwardly from the axis upward. In addition an axial passage 60 connects chamber 32 with the feed distribution chamber at the top of the cap.

In operation for the separation of feed liquid into separate parts, the feed liquid is fed to the centrifuge and upwardly through the channel 20 in the bowl spindle 13, and radially outward through the hole 21 in the nut 14 into feed distribution chamber 22. In this space the accelerating wings (not shown) accelerate said feed liquid to the angular rate of rotation of the bowl. The feed liquid then passes through the passages 25 and upwardly through the vertical channels 24 in the disc stack 16, and then into the thin spaces between the discs. In the thin stratified layers between the discs effective separation of the liquid components takes place under the influence of centrifugal force. The lighter liquid component moves toward the axis along the upper surface of the individual discs into the central channel 26, and ultimately out of the centrifuge in a conventional or other manner. The heavier liquid component moves away from the axis of the bowl along the lower surface of the individual discs into an annular channel (not shown), and finally out of the top of the bowl, also in a convention or other manner.

In view of the large difference in density between gas and liquid fed to the centrifuge, and the correspondingly greater ease of separation of gas from liquid than the separation of liquid components from each other, gas fed to the centrifuge along with the liquid mixture rapidly separate in feed distribution chamber 22, forming a cylindrical core of gas surrounded by liquid. In the absence Qt v n means th as aeet mhlete u t re ehes h ut et e he ubula pa s e 25 and hen a y u th r has ed th t e entr uge ass s he hi s th d sh te le r h pass ng t war he a i ef the Lew-e d es nd reating a u hh n n ha p ti a the ewl wh eh mpairs pa at on E e mor und sira le when as eeeuthel t s a pu at ng e d he e se a at n eh m r re u ts: As e r be visualized above thed e tack pport 15:. the liquid a er ex ends t9 he ax s hi t e he he e e ts a i h e ntes u e e th a t ed beneath th di e t e s hh- Pett 5 end in some ins ances as much as .0 hehud per square inch additional pressure may be requi d to eed l uid ht e a hewl e ee ve t enal size and pe whe as s se trape' t in the h-ewlhis h h heels pres sure i u ld upland hate the le e at the liq id in the distribution chamber 22 outward to the point at which gas escapes through feed passage 25. This escape is of course accompanied by an immediate drop in back pres sure as the liquid level moves inward only to be followed by ahet er pr ssute build u ete- She tuat n i haek p essure esu ts in u ng teed Whieh lt n a ia e s parat on the he In a ee e ieua hewl, passa e is P Yi o an a ia ees t eu 9t the. teed di tr o amber t teu h the d se sta k. see ert to e central eh he ll the ga Whieh. is it; t eh at of gat n ha ee t e sepa ated the feed t bu i etn er 22 flows through this passageway together with a part of the liquid mixture fed to the centrifuge. Both the gas and this portion of the liquid feed mixture are picked up by the discharging stream of separate lighter component flowing through the central channel 26, and are discharged together therewith at the top of the centrifuge bowl. With this conventional method of releasing the gas which is separated beneath the conical skirt of the disc stack support 15, the lighter liquid component which has been eifectively separated in the disc stack is polluted with both the gas and a portion of the feed liquid. The rotating stream discharging from the rotating centrifuge bowl into the non-rotating receiver is subjected to intense shear with the result that the polluting gas and feed liquid is intimately intermixed with the pure lighter liquid component. Even in those cases as in the separation of neat soap from nigre where a slight pollution of the neat soap with a portion of nigre may be tolerated, the subsequent separation of the very finely divided air from the viscous neat soap is accomplished only with considerable difliculty.

An apparatus embodying the present invention will vent the gas from the feed distribution chamber so that gas does not enter the separation chamber. Means are provided to close the vent when the gas is vented and the feed distribution chamber is filled with liquid. When the feed distribution chamber is filled with feed liquid substantially to the axis of the bowl, the liquid under centrifugal pressure will work against the working end 56 to float the valve body to its inward or closed position. In this position the pointed or seating end 52 will rest against seat 40 to close the vent line means 30. It is apparent that to be effective, the buoying pressure on the Working end 56 must overcome the mass of the valve body 50 as acted on by centrifugal force. This is assured by the preferred arrangement disclosed in FIGURE 2 wherein a portion of the valve body is disposed on the opposite side of the axis of the bowl from the working end 56. This portion offsets a portion of equal mass on the opposite side of the axis to reduce the outward urging of centrifugal force on the valve body 50.

Obviously when a core of gas develops centrally in the distribution chamber 22 so that the centrifugal pressure of the liquid working on the end 56 is not suflicient to float body 50 to seating position, the body will move outward to an outer limit established by the abutment of the working end 56 against snap ring 36 to permit venting the gas out of the bowl through passage 46.

he fins v54 en beer 5. her it ree flow ot teed eutertlty .aleh bod .50 a h es' er l ps: a d dr n 8 ass es a eed w l he es a c t r u h. t e vent ine me ns 30 whet t e al e body .50 epehs after bein esetlt A ial as a e 6.9 ro ides i ee nmunie t en of he paeee' e 'e 921 14 w t t e. hambe 3.2- t s ures that gets under p hte ill no be t a ed i the spa e ab ve ear and hat as a t ae utn l etes will immed tel Pas in mber 32 te in ue ce pe at en .ef the a been so.

A rtted fied a paratu euthedy h the n nti n s sh n in FIGURE 4 wherein the primedform of the same reference numeral is used to designate parts corresponding to a s t h preterretl F GURE 2 et het itttent- In h F GUR 4 embo iment th s at 0' is. ubstani y ne e 92 he e h and the ax al Passa e 0' settisfies h P o s e eem i hesi b Pa sa es 0 and s i t e URE? mb d ment,-

o a the y .0 h eeh rif el Pt shr of the q d st t et h t a d urging o he valve ody 50- acted upon by centrifugal force at its center of mass, The centrifugal pressure required to float body 50' ina d Will b g a a were r ions e etiy .0 i p e on O p ite s of e x as in the IGURE embodiment.

The reliability of operation of the apparatuses embodying my invention is attributable to a number of factors. ma y becau e b 0 i r i and eeted 9a w h certainty" by definite opposing forces is it efiectiye, Additionally' its reliability is attributable to its freedom for bodily motion within limits transverse of the axis. Its motidn is unhampered by attachments to other parts of the apparatus. Finally the walls of chamber 32 acting on the distal edges of fins 54 assures perfectly directional movement toward and away from seat 40 for a sure precise seating.

While for the purpose of convenience the invention has been described in connection with a particular type of centrifugal separator bowl, it may advantageously be used with other types of centrifugal bowls whether adapted for separation of liquids, their clarification or otherwise, as for example, centrifugal clarifier bowls for the separation of non-liquid or solid particles froma liquid. It may also be used as a deaerator wherein the prime purpose is to separate gas from the feed liquid, and the clarification of the liquid is incidental. There would be no need to provide such apparatus with a disc stack.

In the embodiment shown the vertical channel 24 extending through the disc stack may be closer to or farther away from the outer edges of the discs, or, and particularly in the case of clarifier bowls, they may be omitted entirely, these and other modifications being well known to those skilled in the art. Also, and particularly in the case of clarifier bowls, the conical skirt of the disc stack support may be so modified, such as in well known manner, that the liquid flowing through the centrifugal bowl is fed directly from the feed distribution chamber to the annular channel surrounding the discs. Furthermore, while I have described the invention as applied to centrifugal bowls provided with discs for the accelerating and decelerating of the liquid as it flows radially outwardly and inwardly, respectively, within the bowl, and for the stratifying of the liquid into thin layers, other types of accelerating-decelerating devices may be used, for example, the main separating chamber 17 may be provided with the well known wing type of accelerating-decelerating device as illustrated in U.S. Patent 1,401,196, or the spiral blade type of accelerating-decelerating device as illustrated in US. Patent 2,138,468. There is also shown in these patents means for distributing the feed. Combinations of various types of accelerating-decelerating devices also may be employed, such as those known in the art.

Having more particularly described my invention, it is to be understood that this is by way of illustration and not by way of limitation, and that modifications may be made without departing from the spirit of the invention. Thus while my invention has been more particularly described in connection with a bowl adapted to be rotated about a vertical axis, it will be understood that my invention is similarly adaptable to a bowl rotating about any other axis, such as a horizontal axis.

Other modifications will occur to persons skilled in the art upon becoming familiar herewith. Accordingly, it is intended that the patent shall cover, by suitable expression in the claims, the various features of patentable novelty residing in the invention.

I claim:

1. A centrifuge bowl divided internally by a partition segregating a lower distributing compartment from an upper primary separating zone, means for feeding feed mixture into the distributing compartment, said partition having ports spaced below the top of the compartment through which feed passes into the primary separating zone, the bowl having a central hub with an axial opening adapted to receive a drive spindle, said hub having a vent opening in its upper end and a vent passage from the undersurface of the bowl to the vent opening, a hub cap removably secured against and over the hub and having a valve chamber with a valve seat opening at one end and a passage extending between the vent opening and the valve seat opening, the valve chamber being disposed in a direction transverse to the axis of the bowl and having a seat surrounding the valve seat opening, the opposite end of said valve chamber from the seat mounting stop means and being open to the inside of the distributing compartment above the uppermost of the ports, a

rigid elongated cylindrical valve element disposed for reciprocation in said valve chamber and having a plurality of outwardly directed fins engaging the walls of said valve chamber and serving to guide said valve element in movement toward and away from said seat, the end of said valve element toward said seat being pointed, said valve element normally held against the seat by the centrifugal pressure of liquid in the bowl but thrown away from said seat to the stop means by centrifugal force in the absence of sufficient pressure.

2. The centrifuge of claim 1 wherein the passage in the hub and the passage in the hub cap are connected through an annular channel communicating with both passages.

3. The centrifuge of claim 1 wherein the seat is spaced from the axis of the bowl and on the opposite side of the axis from the center of gravity of the valve element.

References Cited in the file of this patent UNITED STATES PATENTS 1,277,676 Wright Sept. 3, 1918 2,141,025 Strezynski Dec. 20, 1938 2,417,747 Flowers Mar. 18, 1947 2,712,896 Boldrin July 12, 1955 2,712,897 Kusserow et al. July 12, 1955 2,717,119 Jones Sept. 6, 1955 2,873,910 Steinacker Feb. 17, 1959 2,985,361 Smith May 23, 1961 FOREIGN PATENTS 373,560 Great Britain May 26, 1932 610,305 Germany Mar. 9, 1935

Claims

1. A CENTRIFUGE BOWL DIVIDED INTERNALLY BY A PARTITION SEGREGATING A LOWER DISTRIBUTING COMPARTMENT FROM AN UPPER PRIMARY SEPARATING ZONE, MEANS FOR FEEDING FEED MIXTURE INTO THE DISTRIBUTING COMPARTMENT, SAID PARTITION HAVING PORTS SPACED BELOW THE TOP OF THE COMPARTMENT THROUGH WHICH FEED PASSES INTO THE PRIMARY SEPARATING ZONE, THE BOWL HAVING A CENTRAL HUB WITH AN AXIAL OPENING ADAPTED TO RECEIVE A DRIVE SPINDLE, SAID HUB HAVING A VENT OPENING IN ITS UPPER END AND A VENT PASSAGE FROM THE UNDERSURFACE OF THE BOWL TO THE VENT OPENING, A HUB CAP REMOVABLY SECURED AGAINST AND OVER THE HUB AND HAVING A VALVE CHAMBER WITH A VALVE SEAT OPENING AT ONE END AND A PASSAGE EXTENDING BETWEEN THE VENT OPENING AND THE VALVE SEAT OPENING, THE VALVE CHAMBER BEING DISPOSED IN A DIRECTION TRANSVERSE TO THE AXIS OF THE BOWL AND HAVING A SEAT SURROUNDING THE VALVE SEAT OPENING, THE OPPOSITE END OF SAID VALVE CHAMBER FROM THE SEAT MOUNTING STOP MEANS AND BEING OPEN TO THE INSIDE OF THE DISTRIBUTING COMPARTMENT ABOVE THE UPPERMOST OF THE PORTS, A RIGID ELONGATED CYLINDRICAL VALVE ELEMENT DISPOSED FOR RECIPROCATION IN SAID VALVE CHAMBER AND HAVING A PLURALITY OF OUTWARDLY DIRECTED FINS ENGAGING THE WALLS OF SAID VALVE CHAMBER AND SERVING TO GUIDE SAID VALVE ELEMENT IN MOVEMENT TOWARD AND AWAY FROM SAID SEAT, THE END OF SAID VALVE ELEMENT TOWARD SAID SEAT BEING POINTED, SAID VALVE ELEMENT NORMALLY HELD AGAINST THE SEAT BY THE CENTRIFUGAL PRESSURE OF LIQUID IN THE BOWL BUT THROWN AWAY FROM SAID SEAT TO THE STOP MEANS BY CENTRIFUGAL FORCE IN THE ABSENCE OF SUFFICIENT PRESSURE.