US2924378A - Centrifuges - Google Patents

Description

' Feb. 9, 1960 Fig.

. H. c. FlTZIMMONS 2,924,378 CENTRIFUGES Filed Jan. 22, 1957 2 Sheets-Sheet 1 INVENTOR.

HAROLD C. F ITZSIMMONS ATTORNEY United States Patent CENTRIFUGES Harold C. Fitzsimmons, West Chester, Pa., assignor to The'Sharples Corporation, a corporation of Delaware Application January 22, 1957, Serial No. 635,495

2 Claims. (Cl. 233-46) This invention relates generally to centrifuges for separating materials of different. densities. More particularly the invention relates to a centrifuge having ,a dividing cone in its bowl and which during operation discharges separated materials along the axis of rotation, there being no column of air in the bowl around the axis of rotation. Since during operation the bowl is thus 1 for'th'e lighter. material. A discharge path for theheavier material is formed between the outside surface of the "dividing cone includingits extension and'the bowl top and a cooperating coaxially positioned cylindrical member or'sleeve attached to'the bowl top and surrounding the dividing cone extension for at least a portion of its length. In general, the dimensions of the annular channel between the dividing cone extension and the cylindrical member surrounding it determine in part the discharge pressure of the lighter separated material.

Both the dividing cone extension and its surrounding cylindrical member are concentrically surrounded by respective fluid-receiving means attached to the stationary frame portion of the centrifuge. These stationary fluidreceiving means'include liquid-tight seals respectively in contact with the rotating dividing cone extension and the surrounding cylindrical member so as to confine separated materials in the fluid-receiving chambers around the rotating dividing cone extension and the surrounding cylindrical sleeve which open'i'nto these chambers.

The cylindrical sleeve is secured to the topof the bowl which is balanced so that the bowl-driving spindle on whichthe' bowl is mounted and the cylindrical sleeve rotate about a given axis without substantial deviation therefrom. The fluid-receiving means and seals are positioned around the dividing cone extension and the cylindrical sleeve substantially concentrically with respect to the established axis of rotation, the seals being movably adjustable (in a preferred embodiment) to permit them to correct for slighterrors in their initial coaxialpo-si tion with respect to the established axis of rota-tionof the dividing cone extension and the cylindrical sleeve. Concentricity with the cylindrical sleeve as well as mechanical support are provided for the dividing 'cone extension by means of vertically extending ribs on the outside surfaces of the dividing cone extension which contact the inside surfaces of the surrounding cylindrical sleeve. (These ribs thus occupya portion of the annular channel between 'the'dividin'g' cone extension the surrounding cylindrical member.) i

In the case where the dividing cone extension is integrally or infiexibly mounted on the dividing cone, proper alignment between the dividing cone extension and its surrounding cylindrical member can only be obtained when the dividing cone itself is coaxially positioned with respect to the bowl and the cylindrical sleeve; Since the dividing cone itself is fixed in position with respect to the bowl (by means of ribs which contact the inside surfaces of the bowl and cannot move radially), it follows then that the coaxial alignment of the dividing cone extension with respect to the dividing cone must be well-nigh perfect if the dividing cone extension is to rotate concentrically with its surrounding cylindrical member.

Thus if a dividing cone extension integrally mounted on a dividing cone is even slightly out of axial alignment with respect to the dividing cone, the surrounding cylindrical sleeve is not able to bring the dividing cone extension into a position of coaxial alignment. Hence the dividing cone extension will rotate somewhat eocentrically with respect to its fluid-receiving chamber and liquid-tight seal and produce at least excessive wear and strain on this seal if not rendering it completely inoperative altogether.

It is difiicult' to manufacture a dividing cone with such an integral tubular extension thereon and obtain the precision of coaxial alignment required. Furthermore, once a dividing cone extension which is integrally joined to its dividing cone is misaligned, the misalignment is permanent, being extremely diflicult if not impossible ,to correct. Heretofore it has been necessary to either remove the dividing cone and re-align the dividing cone extension or replace the dividing cone altogether. Since variations in dividing cones are unavoidable, the entire bowl must be rebalanced in the event of the replacement of a dividing cone.

It will also be appreciated that with a dividing cone having an integral dividing cone extension it is not only exceedingly difficult but virtually impossible to obtain simultaneously optimum fits diameter-wise between the dividing cone extension and its surrounding cylindrical member and between the dividing cone itself and the bowl top. In general, because of its critioality in the materialseparating function and in the balancing of the bowl, it is preferred to obtain the best diametric fit between the dividing cone and the bowl top. Hence, heretofore a somewhat less than optimum diametric fit between'the dividing cone extension and its surrounding cylindrical member had to be tolerated to some extent.

According to the present invention, a dividing' cone extension is provided which is flexibly joined to the dividing cone. Such a flexible mount permits the surrounding cylindrical sleeve to bring the dividing cone extension into a position of coaxial alignment with respect to the axis of rotation of the surrounding cylin drical sleeve and thus into. proper concentric alignment with respect to the fluid-receiving means and seals for the dividing cone extension. Likewise since the dividing cone extension and the dividing cone are no longer integrally joined, more optimum diametric fi-ts between the dividing cone extension and its surrounding cylindrical member may be, independently obtained.

The invention will be more particularly described with reference to the drawings in which:

Figure 1 is a sectional elevational view of. a centrifugal bowl having a disc stack therein and embodying the invention;

Figure 2 is a sectional elevational view of the stem and dividing cone assembly according to the invention; and

Figure 3 is a cross sectional plan viewtaken along the line 3'-3 of Figure 2.

Referring nowto Figure, l, a centrifuge of the full bowl.

type is shown having a bowl shell 11 and a bowl top 25 providing a separating chamber in which is located a nest 12 of stacked conical discs 13. The stacked conical discs are spaced in vertical relation to each other and have central holes 14 as shown. The vertical spacing of these discs may be accomplished by any suitablc means such as by the spacers 15 fastened to the upper surfaces of the discs 13 thereby forming thin separating spaces between the discs. As shown, the aligned central holes in the individual discs provide a non-obstructed vertical channel or free space Iii-extending axially up throughthe discs. This vertical channel is shown coaxialwith the axis of rotation of the bowl shell 11. Other arrangements of constructions may be substituted within the skill of the art, such as the conventional solid center post. I

An inlet or feed-in channel 20 is provided in the drive spindle 21 to-which the bowl shell 11 is attached.

In addition to the central holes already described, the discs are provided with holes positioned outwardly from the center thereof and one above the other to form the conventional ciroumferentially spaced vertical channels 34 through the vertical length of the disc stack 12, one channel 34 being shown. Above and in contact with the uppermost disc 13 is the dividing cone 22, provided with a plurality of circumferentially-spaced longitudinal ribs 23. The dividing cone 22 with the inside of bowl top 25 in contact wtih the ribs 23 cooperate together to form a heavy component outlet channel 24 leading from the outermost portion of the separating chamber. The dividing cone 22 terminates in an integral cylindrical portion 26 having extensions of the ribs 23 on its sides and top and which also cooperates with a like cylindrical portion'27 of the bowl top 25.

The dividing cone has a'tubular extension 28 on the upper part of the integral cylindrical portion 26 of the dividing cone 22. The inside channel 29 of the dividing cone extension 28 provides an outlet passage for light fluid component from the free vertically extending central space 18 within the dividing cone 22. Extending vertically along the outside surface of the dividing cone extension 28 are ribs 28a which contact the inside surface-of the surrounding cylindrical member .41. These ribs provide the dividing cone extension with mechanical support and also help bring it into concentric alignment with respect to the cylindrical member.

A- center structure consisting of vertically extending ribs or bars 17 extending up about the central channel 18 is provided. Preferably .these ribs are attached to or made integral with the base member 19 and the collar 17a. The ring 17a, to which the upper ends of the ribs 17 are joined or made integral therewith, is in turn contained within the cylindrical extension 26 of the dividing cone 22 and indexed thereto by means of a pin 40. Slots provided in the inner peripheral edges of the discs register with and orientate and hold the discs in place wtih respect to the ribs 17. A more complete description of this structure and advantages thereof will be found in US. Patent No. 2,717,119 issued to L. D. Jones and assigned to the instant assignee. This arrangement permits the decelerated lighter phase fluids (i.e.'

cream) to swirl ahead of the rotation of the bowl and to thus prevent or alleviate clogging.

The terminal portion of the heavy and light phase discharge channels 24 and 29, respectively, are formed by the tubular dividing cone extension 28 of the dividing cone and a cylindrical member or sleeve 41 which surrounds the dividing cone extension 28 for a portion of its length and is secured to the cylindrical extension 27 of the bowl top 25, Thus the heavier phase fluid is ultimately discharged into the stationary heavy phase receiving chamber designated generally by reference numeral 43. The lighter phase fluid is discharged from the end of the dividing cone extension 28 into the stationary light phase receiving chamber also designated generally by reference numeral 42. Since both the dividing cone extension 28 and the cylindrical member 41 are rotating and their surrounding fluid-receiving chambers 42 and 43 are stationary, liquid-tight seals must be provided as shown around these rotating parts.

Seals are employed at both the inlet and outlet ends of the bowl. The use of seals for full bowl operation is well understood in the art and may be of any suitable type and construction. Preferably however seals of the type shown and described in Patent No. 2,554,622 dated May 29, 1951 and issued to L. D. Jones and assigned to the instant assignee are employed. It should be particularly noted that the seals are between the stationary liquid-receiving portions 43 and 42 of the centrifuge and the rotating cylindrical member 41 and the rotating dividing cone extension member 28 respectively. The preferred seals operate by reason of the pressure of the fluid being discharged so as to effect sealing between the respective stationary portion defining the liquid-receiving chambers and the rotating parts. It will be apparent that ofi-axial displacement of either the dividing cone extension 28 or the cylindrical member 41 may result in complete failure of the seals or at least in excessive wear thereof. Furthermore such off-axial displacementneeeccarily results with respect to the dividing cone extension 28 when the dividing cone 22 and the dividing cone extension 28 are inflexibly joined and the position of the dividing cone extension becomes altered, even slightly, with respect to the dividing cone since the dividing cone extension is unable to assume a position independent of the position dictated by the dividing cone even though the surrounding cylindrical member 41 would tend to bring the dividing cone extension into coaxial alignment with respect to itself.

In operation, the liquid to be separated, such as whole milk, is introduced into the bowl through the inlet channel 20 provided at the bottom thereof and through inlet openings 30 in a nut or cap 31. The liquid passes into the chamber 32 and through conventional circumferentially spaced channels 33 (one channel 33 being shown) and thence upwardly in vertical channels 34 and into the spaces between the discs of the stacked disc nest 12. The action of centrifugal force separates the whole milk into cream and skim milk. The heavier phase, such as the skim milk, passes outwardly with respect to the axis of rotation of the centrifuge and then upwardly to the heavy component discharge channel 24. The separated lighter phase, such as for example cream, n oves towards the axis of rotation of the centrifuge and eventually enters the free space 18 extending vertically upward through the disc stack 12 and thence through the discharge channel 29 provided in the dividing cone extension 28 which is provided on the cylindrical extension 26 of the dividing cone 22. It will be noted that the terminal discharge channels for both of the separated fluidsare relatively adjacent each other, separated only by the wall of the dividing cone extension 28.

Referringnow. to Figure 2, it will be noted that both the dividing cone 22 and the bowl top 25 terminate in corresponding cylindrical extensions 26 and 27, respectively. The dividing cone extension 28 extends. coaxially through the cylindrical member 41 which is secured to the cylindrical extension v27 of the bowl. The heavy component discharge channel or outlet 24 is thus formed between the dividing cone extension 28 and the cylindrical member 41 while the light component fluid channel 29 is provided by a central opening through the dividing cone extension 28. According to the invention the dividing cone extension 28 is movably mounted or flexibly joined to the cylindrical extension 26 of the dividing cone. This is accomplished by providing the integral cylindrical extension 26 of the dividing cone 22 with a slightly larger internal diameter than the external diameter of the lower part of the dividing cone extension 28. Hence the dividing cone extension 28 may. be inserted into the integral cylindrical extension 26 of the dividing 'cone and held thereto for rotation therewith by means of a partial or semi-circular keyway 35a provided in the dividing cone extension 28. The keyway receives a pin 36 fixedly secured to the integral cylindrical portion 26 of the dividing cone 22 to thus prevent relative rotation of the two parts with respect to each other. The pin 36 also serves to index the dividing cone extension 28 and the integral cylindrical portion 26 of the dividing cone so as to align the radially extending portions 39 on ribs 28a with ribs 26a positioned on and secured to the top of cylindrical portion 26.

In order to prevent any communication of fluids in the two discharge channels 24 and 29 through the joining surfaces of the dividing cone extension 28 and the integral cylindrical portion 26, the dividing cone extension 28 is provided with an annular groove 37 in which is inserted a ring 38 of resilient material, such as rubber. This rubber ring when inserted in place in this groove of the stem 28 may have a slightly larger diameter than that of the central opening of the cylindrical portion 26 of the dividing cone 22 so as to protrude radially outwardly from the annular groove 37 with the result that the dividing cone extension must be mounted or inserted into the cylindrical extension 26 under force. In this embodiment an extremely tight seal is provided by the now compressed resilient material between the two parts so joined. Alternatively, the resilient ring 38 may have a diameter slightly less than that of the central opening of the cylindrical portion 26 of the dividing cone so that upon insertion, the ring does not protrude outwardly radially to contact the inner surface of the cylindrical portion 26. In this embodiment the density of the rubber ring should be greater than the density of the liquid so that with the centrifuge in operation and rotating, scaling is accomplished because the resilient material 9 will be urged outwardly and spread by centrifugal force to become very tightly compressed against the point between the dividing cone extension 28 and the cylindrical portion 26. It will be appreciated that the fluids involved will be under increased pressure with increasing rotation and hence more likely to seek escape paths however small. On the other hand increasing rotational speed will produce a tighter and tighter seal between the dividing cone extension 28 and the cylindrical portion 26 to deny communication through the joints therebetween. Hence the very force tending to cause the fluids to mix after separation is employed to render such mixing impossible and to achieve a very efiective seal between the joined parts.

It should also be appreciated that in the embodiment wherein the resilient ring 38 must be compressed under force for insertion into the cylindrical portion 26 of the dividing cone, the dividing cone extension 28 need not be inserted all the way into but may be held at any vertical position in the cylindrical portion 26. In such circumstances the upper horizontal surfaces of the radially extending portions 39 of the ribs 28a on the dividing cone extension contact the horizontal surfaces of the inside of the bowl top 25 which is advantageous in preventing any possible swirling.

Alternatively the rubber ring may be otherwise mounted. Thus the diameter of the rubber ring and/or the depth of the groove therefor may be varied so as to permit the dividing cone extension to be inserted to any desired depth in the cylindrical portion 26 of the dividing cone 22.

The flexibility of the dividing cone extension 28 with respect to the dividing cone 22 permits the dividing cone extension to assume a position of alignment as dictated by the surrounding cylindrical member 41 independently of the disposition of the dividing cone. Thus the surrounding cylindrical member 41 can pull the dividing cone extension 28 into position so that these two parts are concentric with respect to each other. Hence, since the fluid-receiving chambers 42 and 43 as well as the respective seals carried thereby for the dividing cone extension 28 and the cylindrical member 41 are concentrically located with respect to the cylindrical member 41, the dividing cone extension 28 is likewise concentrically positioned with respect to its respective fluid-receiving chamber 42 and seal.

Other and unexpected advantages are realized by the construction of the invention. Among these is the ability to obtain a separate diametric fit between the dividing cone extension 28 and the cylindrical member 41, which fit is independent of the diameter of the cylindrical portion 26 of the dividing cone and the diameter of the cylindrical extension 27 of the bowl top 25 as well as independent of the shapes of.and fitting between the dividing cone 22 and the bowl top 25. Such independently obtainable fittings make possible better design for control of the discharge pressure of the light component fluid. Furthermore, since dividing cone extensions having different dimensions (i.e., the arcuate width of the groovedefining ribs) may be employed, diflerent discharge pressures may be established as desired. For example, if a given pressure is established in the heavy component discharge channel with a dividing cone extension having ribs of a given arcuate width, employing a dividing cone extension having thinner ribs will increase the channel dimensions and result in a lower pressure in this channel, While thicker ribs will decrease the channel dimensions and result in a higher pressure.

A concomitant advantage of flexibly mounting the dividing cone extension on the dividing cone lies in the possibility of interchanging different dividing cone extensions on a given dividing cone as just indicated. This unexpected advantage may be realized according to the invention without the necessity of rebalancing the bowl since the dividing cone itself need not be changed. Thus dividing cone extensions may be removed and replaced with case if damaged or where it is desired to obtain changes in discharge pressures in the manner just described in the preceding paragraph.

There thus has been shown and described a centrifuge of the full bowl type having a dividing cone with a flexibly-joined and movably-monnted extension. It should be understood that while the invention has been described with particular reference to a centrifuge having a nest of discs in the separating chamber of the rotating bowl, the invention may be used with centrifuge bowls having other internal structures and arrangements. The essential requirements of the centrifuge incorporating the invention is that it operate on the full bowl principie and have a dividing cone whereby the separated liquids are ultimately discharged close to and along the axis of rotation of the bowl. Also it is not necessary that the dividing cone extension be mounted to an integral cylindrical extension of the dividing cone although this is preferred because of its simplicity and ease of manufacture. An exemplary alternative construction would be to provide the dividing cone with mouth or opening thick enough to receive the stem and the sealing ring described.

While the invention has been described with particular reference to the separation of whole milk into skim milk and cream, it is to be understood, however, that this is only by way of example and that the invention may be applied to the centrifugal separation of materials generally.

What is claimed is:

1. The combination with a centrifuge having a rotatable bowl and a dividing cone in the separating chamber of said bowl positioned therein to rotate therewith and to maintain in divided condition effluents of different densities in their discharge from said bowl, said dividing cone having a hollow extension projecting axially from said bowl to provide an outlet along the axis of rotation,

and said bowl having a tubular member surrounding said' extension to provide an outlet adjacent to the axis of rotation, of. an axially slidable connection between said extension and said cone, circumferentially spaced longitudinal ribs on said extension in contact with the interior of said tubular member, said tubular member being mounted on said bowl to rotate coaxially therewith and engaging said ribs to secure said extension in position for coaxial rotation with said bowl, said connection between said extension and said cone permitting the required relative movement therebetween, and means for maintaining said extension in operative position relative to said cone.

2. A centrifuge bowl of the kind described having a dividing cone in its separating chamber, said dividing cone having a hollow extension extending outwardly from said bowl centrally thereof to provide a discharge path for one effiuent, and said bowl having a tubular member surrounding said extension to form a discharge path for a second effluent, characterized in that said extension slidably engages said cone axially thereof with means forforming a seal therebetween, in that said extension has longitudinal ribs on its outer surface, in that said tubular member is secured to said bowl to rotate coaxially therewith, and in that said tubular member engages said ribs to position said extension for coaxial rotation with said bowl.

Forsberg June 9, 1936 Jones Sept, 6, 195 5

Images