US3371858A - Centrifuge discharge means - Google Patents

Description

' Mal-c115, 1968 L. SHAPIRO 3,

CENTRIF'UGE DISCHARGE MEANS Filed March 17, 19766 INVENTOR. LEONARD SHAPIRO ATTORNEY United States Patent 3,371,858 CENTRIFUGE DISCHARGE MEANS Leonard Shapiro, Upper Darby, Pa., assignor to Pennsalt Chemicals Corporation, Philadelphia, Pa., 3 corporation of Pennsylvania Filed Mar. 17, 1966, Ser. No. 535,184 3 Claims. (Cl. 233--14) ABSTRACT OF THE DISCLOSURE In a centrifuge equipped with an annular groove which opens inwardly toward the rotational axis for receiving a skimmer disc, scattering of pasty fluid from the bowl is eliminated by providing the skimmer disc with an axially extending baffleextending into the groove and also by providing the bowl with radial vanes immediately outward of the groove.

This invention relates to the centrifugal separation of a pasty fluid from a mixture and the discharge of the pasty fluid from a centrifuge bowl in a manner which reduces the possibility of throwing of the pasty fluid by the centrifuge.

In the discharge of liquids from a centrifuge bowl a common expedient is to provide the bowl with an inwardly facing annular trough or pocket into which the liquid to be discharged is led by appropriate passages in the bowl structure. A skimmer or paring device is positioned to extend into the annular trough or pocket and to scoop up the liquid as it races by. One of the advantages of the skimming or paring device is that the liquid is discharged from the centrifuge under a positive pressure, thus eliminating the need for additional pumping machine. An example of such a discharge arrangement is disclosed in my presently pending application Ser. No. 419,086, filed Dec. 17, 1964, now US. Patent No. 3,310,- 232.

When using the discharge devices generally described above, processors in the past have experienced some difficulty in the movement of a separated pasty fluid inward about the spindle and upward to be thrown out off the machine. This spitting has been a health hazard since often the fluid is hot (140160 F. in the case of starch mud, for instance) and has resulted in serious burning of the hands and eyes of the operator. While such movement of a fluid has been generally correlated with process variations, it has often been unaccounted for and has been unpredictable and a great nuisance. It has required too frequent mopping up operations. Less important, this spitting of pasty fluid has represented some loss of product. No effective means have been devised for this undesirable characteristic of skimmer discharge machines.

The present invention is concerned with the avoidance of spitting of separated pasty fluid in a skimmer discharge centrifuge.

Other objects of the invention will be understood with further reference to the following specification and the attached drawing forming a part thereof and in which:

FIGURE 1 is a sectional view of the upper portion of a centrifuge embodying the invention;

FIGURE 2 is an enlarged sectional view taken on the line 2--2 0f FIGURE 1; and

FIGURE 3 is an enlarged portion of FIGURE 1 diagrammatically representing the flow of pasty fluid in the bowl.

Briefly, then, the invention relates to a centrifuge in which the skimmer discharge is provided with antispitting means. Specifically these means may comprise a centrifugal seal or trap by which centrifugal force is utilized to reject the vagrant pasty fluid back into the skimmer pocket.

Referring more specifically to the drawings, FIGURE 1 is a fragmentary sectional view of a centrifuge embodying the invention and generally designated 10. It comprises a bowl 12 mounted for rotation by a suspending and driving shaft 14. The bowl structure may include a set 16 of frusto-conical disc (only two of which are shown) which are disposed about a varied center tube 16a and operate in the conventional manner to increase the efficiency of the separation. The feed mixture is delivered to the lower end of the centrifuge by feed means (not shown).

Mounted on the top of the bowl 12 is the heavy phase discharge housing 18 and the light phase discharge housing 20. The housing 20 is supported on the dividing cone 22 secured between the upper end of the center tube 16a and the bowl top. In between the dividing cone 22 and housing 18 are a plurality of spaced ribs 24 which space the elements properly and permit passage of the heavy liquid from the centrifuge bowl into a pocket 26 facing inwardly and formed between the housings 18 and 20. The ribs widen in the pocket 26 and comprise part of radial vanes 28 which assure rotation of the liquid within the pocket 26 with the bowl.

The housing 20 together with the inward annular wall 30 also supported on the dividing cone 22 forms a pocket 32 which is provided with vanes 34. In operation separated light discharge, a pasty fluid from the centrifuge bowl spills over the annular wall 30 into the pocket 32. The wall 30 is formed with a plurality of radially inward extending vanes 30a.

Surrounding the drive and supporting shaft 14 is a stationary discharge assembly comprising the paring discs 36 and 38. The structure of the paring discs are comparable. As shown in FIGURE 1 the disc 36 is annnular and provided with passages 37 which may be curved and extend from the periphery of the device to an inward discharge channel 40. The channel is formed between the tubular exterior wall 42 of the paring device 36 and the tubular wall 44 of the lower paring device 38. Spacing ribs 46 are provided to hold the two tubular portions in proper relation.

The lower paring device 38 comprises a pair of spaced sideplates with battles in between. Discharge passages 48 extend inward from the periphery of the device to the inward discharge channel 50 between the tubular element 44 and the inner tubular element 52. Ribs 54 hold these two elements in proper relative position.

The paring device assemblies are supported as shown on the centrifuge cover which is stationary. The upper ends of the passages 40 and 50 communicate respectively with discharge conduits 56 and 58 as shown.

The opposite faces of the paring device 36 are provided with spaced annular ribs 60 and 62 in accordance with patent application Ser. No. 419,086, filed Dec. 17, 1964, now US. Patent No. 3,310,232. These ribs which are disposed concentrically about the axis of the centrifuge serve to deflect outward and into the liquid of the pocket 26 liquid moved inward by the secondary flow phenomenon. It will be understood that the liquid level is such that some ribs are normally immersed in the liquid in the pocket 26.

Similarly ribs 60' and 62 are provided for the same purpose on the paring device 38 (FIGURE 3).

A splash shield 63 is provided on the underface of the paring device 36 and also serves to control turbulence or splashing. Passages 65 through the paring disc 36 provide means for venting gas pressures which may develop on either side of the disc.

Mounted on stationary structure comprising the discharge conduits 56 and 58 is a suplemental liquid introducing nozzle 64. The nozzle has a large end adapted to receive a supply of supplemental liquid, for instance hot water, and a smaller nozzle end 64a which is perpendicular to the body portion of the structure and directs the liquid in a jet down the annular space between the shaft 14- and the tubular element 52.

Secured to the upper end of the center tube 16a is an annular supplemental liquid deflecting target 66. The target is threadedly received into the upper end of the center tube and bears on its upper surface a plurality of radially directed vanes 68 (FIGURE 3). The inner surface of the target 66 is provided with a seal 70 which may be of elastomeric material and snugly embraces shaft 14 to keep supplemental liquid from flowing downward on the shaft. It will be understood that there is no relative rotary motion between the target and the shaft 14; both rotate at the speed of the bowl.

As shown in the figures the target 66 is formed with a deep annular groove 72 which interrupts the vanes, the groove receives an annular baffle 74 which extends down from the inner tubular element 52. The clearance between the baffle 74 and the walls of the groove 72 are such as to avoid interference as the bowl rotates and the skimmer device 38 remains stationary.

The upper surface of the target and the vanes 68 being at the level of the pocket 32 may direct the supplemental liquid thereinto in a fashion which because of the turbulence on contact thoroughly mixes and homogenizes the incoming supplemental liquid and the pasty or viscous component already in the pocket. This mixing serves to dilute the viscous component, reducing its viscosity and making it easier to discharge out of the passages of the paring device 38.

In operation the feed is delivered to the lower end of the centrifuge by means not shown and the lighter discharge spills over the annular darn 30 and finds its way into compartment 32. Similarly the heavier liquid discharge moves through the passages 24 into the discharge pocket or chamber 26. The paring devices 36 and 38 dip respectively into the rotating pools of liquid in the pockets 26 and 32, and through the paring devices the discharges flow respectively to the passages 56 and 58.

If the lighter phase discharge in the pocket 32 is pushed radially inward by secondary flow adjacent the underside of the paring device 38 (FIG. 3) it will meet the baffle 74 and be deflected downwardly into the groove 72 and against the vanes 68 outwardly of the groove. The vanes 68 will throw the pasty liquid back into the pocket 32 and will prevent it from moving up inside the tubular element 52 to be thrown outwardly at the top thereof.

While it is not a necessary feature of the invention, a diluent which may facilitate discharge of the material in the skimmer pocket 32 through the paring device 36 may be supplied through the nozzle 64, 64a. When this diluent hits the vanes 68 it will be thrown outwardly through the space between the baflle 74 and the groove 72 and ultimately into the pocket 32 as thoroughly explained in the presently pending application Ser. No. 425,412, filed Jan. 14, 1965, now Patent 3,317,126, of which I am co-inventor. Thus the present arrangement which avoids the spitting of liquid discharge by the machine does not prevent the entry into the machine of a diluent as discussed in the earlier patent application. It should be understood, however, that the invention has utility even when such a diluent is not used.

It should be understood that while in the present instance the pasty discharge is the lighter phase, as is usually the case, the pasty discharge may be the heavy phase in which case the rejection-type seal would be applied to the heavy phase pocket. It should similarly be understood that the rejection-type seal described may involve more than one baflie- groove arrangement 74, 72; that is that a plurality of concentric baflie-groove arrangements maybe used.

Therefore, it is to be understood that the above particular description is by way of illustration and not of limitation, and that changes, omissions, additions, substitutions, and/ or other modifications may be made without departing from the spirit of the invention. Accordingly, it is intended that the patent shall cover, by suitable expression in the claims, the various features of patentable novelty that reside in the invention.

I claim:

1. A centrifuge for the separation of a pasty fluid component from a feed mixture comprising a supported drive spindle extending downwardly,

a centrifuge bowl having an axis and mounted on its axis on the lower end of the spindle,

means for delivering feed to the bowl,

an inwardly facing annular pocket disposed on the bowl about the axis with passage means from the interior of the bowl to the pocket for the passage of the separated component,

a stationary skimming device mounted adjacent the bowl and extending outward into the pocket and adapted to skim said component from the pocket,

an annular deflector element closely surrounding the shaft at the level of the pocket and mounted to r0- tate with the bowl, the annular deflector element having a radial face with protruding radial vanes thereon and an annular groove in said face interrupting the vanes, and

an annular baflie disposed on said skimming device and extending into said groove.

2. A centrifuge as described in claim 1 including additionally a stationary nozzle disposed above the bowl and adjacent the shaft and having means adapted to direct a supplemental liquid in a downward stream parallel to and adjacent the shaft and toward said deflector element whereby liquid in the pocket is diluted with the supplemental liquid and reduced in viscosity to facilitate discharge through the stationary skimming device.

3. A centrifuge for the separation of a viscous fluid from a feed mixture comprising a centrifuge bowl, an annular discharge pocket for said fluid mounted on said bowl at one end thereof, a fixed skimmer disc structure extending out into said pocket, said bowl having an annular groove therein inward of the pocket and between the pocket and the outside of the bowl along a leak path, said skimmer disc structure having an annular baflie extending in a direction axial with respect to said bowl, the distal end of the baflle extending into said groove, and a plurality of substantially radial vanes on said bowl structure immediately outward of said groove.

References Cited UNITED STATES PATENTS 2,261,394 11/1941 Lindgren 233-14 FOREIGN PATENTS 827,328 1/ 1952 Germany.

OTHER REFERENCES German printed application 1,140,144, November 1962, Teckentrup.

HENRY T. KLINKSIEK, Primary Examiner,

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