US3365128A

US3365128A - Industrial process and apparatus

Info

Publication number: US3365128A
Application number: US467840A
Authority: US
Inventors: Jr Joseph R Townsend
Original assignee: Pennsalt Chemical Corp
Current assignee: Pennwalt Corp
Priority date: 1965-06-29
Filing date: 1965-06-29
Publication date: 1968-01-23
Anticipated expiration: 1985-01-23

Description

Jan. 23, 1968 J. R. TOWNSEND, JR 3,

I INDUSTRIAL PROCESS AND APPARATUS I Filed June 29, 1965 ATTORNEY JOSEPH R. TOWNSEND,JR.

United States Patent Ofiice 3,365,128 Patented Jan. 23, 1968 3,365,128 INDUSTRIAL PROCESS AND APPARATUS Joseph R. Townsend, Jr., West Chester, Pa., assignor to Pennsalt Chemicals Corporation, Philadelphia, Pa., a corporation of Pennsylvania Filed June 29, 1965, Ser. No. 467,840 4 Claims. (Cl. 233-21) This invention relates to centrifuges. More specifically this invention relates to centrifuges provided with means for discharging a separated fluid under positive pressure especially where the discharging fluid is viscous.

The prior art relating to centrifuging is replete with innumerable discharge devices for removing separated liquid from solid bowl machines. A common expedient is simply the provision of a ring dam or tube darn over which the separated liquid may spill to the outside of the bowl for collection by a suitable cover device. Alternatively, a skimmer tube dips into an inwardly facing trough or pocket mounted on the centrifuge bowl and scoops the liquid as it races by. In a diiferent form the skimmer tube takes the shape of a paring disc which is disposed on the centrifuge axis and extends outwardly on all sides into the trough or pocket. The paring disc is equipped with angled passages into which the liquid rushes as the centrifuge rotates. A suitable inward discharge channel for the disc is provided.

Difficulty has been experienced in the discharge of viscous fluids, either heavy or light, from the centrifuge by means of a paring disc. Certain fluids, such as the protein-fat mud phase in a corn syrup operation, the heavy soap phase in vegetable oil refining,the light phase cheese in a cream cheese operation, have defied discharge through a standard paring disc. Presumably this has been because the centrifugal head in the paring trough or pocket has been insufficient to drive the fluid into the openings in the periphery of the paring disc. In order to overcome this difficulty, these fluids have been diluted to make them less viscous and more susceptible to discharge. While the dilution has made discharge through the paring device possible, it has presented other problems: need for dilution injection equipment, need for subsequent treatment of the discharged fluid to remove the diluent, etc.

I have found that the effectiveness of a conventional paring disc in operation on difiicult-to-discharge fluids may be very greatly enhanced by a simple, yet unobvious modification to its structure. In the modification, portions of the vanes of the paring disc are laid bare by reducing the diameter of one of the side Walls of the disc. Portions of the vanes are thereby exposed. While this has no affect on the pressure of the liquid in the paring trough, it has made possible the discharge of fluids through the paring disc which heretofore have not been possible to discharge. The explanation of the success is not certain, but apparently the vanes of the paring device being exposed in part form a kind of a scoop which serves to better direct the fluid into the channels of the device and to thereby better communicate the pressure in the trough into the device. On the other hand, the exposed vanes in being more prominent than the vanes of the conventional skimmer devices of the prior art accentuates the difference in velocity of the fluid and the paring device. This velocity is then converted into additional head by the paring device.

It is a feature of the invention therefore to provide for a centrifuge having a viscous discharge fluid, an improved paring device which efficiently discharges the fluid under pressure without the aid of a diluent.

Other features of the invention will be apparent from a review of the following specification describing a preferred form of apparatus and reference to the drawings in which:

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

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

FIGURE 3 is an enlarged sectional view of structure within section line 33 of FIGURE 1.

Briefly, in a centrifuge having a discharge paringdevice comprising a circular structure with passages from its periphery to an inward discharge channel, the invention is the improvement of reducing the diameter of one of the side walls to expose portions of the vanes within the paring device.

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 discs which are disposed about a vaned center tube 16a and operate in the convention-a1 manner to increase the efliciency of the separation. The feed liquid 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 discharge housing 18 and the light 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 arid 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 liquid from the centrifuge bowl spills over the annular wall 30 into the pocket 32.

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 2 the disc 36 is annular 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 similarly has extending inward from its periphery discharge passages 48 which extend to the inward discharge channel 5%} between the tubular element 44 and the inner tubular element 52. Ribs 54 hold these two parts in proper relative position.

The paring device assemblies are supported as shown on the centrifuge cover which is stationary. The upper ends of the

channels

46 and 50 communicate respectively with

discharge conduits

56 and 58 as shown.

Focusing now on the particular area of the invention, FIGURE 3 shows that the lower paring disc 38 comprises a top wall 60 and a bottom wall 62. The top wall may be provided with annular ribs 64 to reduce turbulence as described in patent application Ser. No. 419,086, filed Dec. 17, 1964, by Leonard Shapiro. Such ribs 66 may also be on the paring disc 36. Vanes 68 (FIG. 3) are provided between the two walls and extend out to the periphery of the top wall. As shown the vanes may be arcuate in shape so as to smoothly direct the fluid into the discharge annulus.

The under wall 62. of the paring device is reduced in diameter compared to the upper wall by a distance a. In a disc having an 8 inch diameter, the distance a has been roughly 4 inch. Radial reductions of 5-l0% of the radius of the disc have been found eifective. This has exposed a corresponding area of the underface of the vanes.

It should be clear that the reduction in diameter might well be in the upper wall 60 instead of the lower, or indeed on one of the Walls of the disc 36, if the viscous fluid is the heavy phase.

A splash shield 70 is provided on the underface of the paring device 36 and also serves to control turbulence or splashing. Passages 72 through the paring disc 36 provide means for venting gas pressures which may develop on either side of the disc.

It should be understood that variations within the scope of the invention are possible. For instance, the invention may be applied to a centrifuge having a horizontal axis and to the paring device of a centrifuge of an altogether different type, for instance a worm centrifuge.

The present invention may be embodied in other specific forms without departing from the spirit or central attributes thereof and, accordingly, reference should be made to the appended claims rather than the foregoing specifications as indicating the scope of the invention.

I claim:

1. A centrifuge bowl having an axis of rotation, an annular inwardly facing pocket mounted on the bowl concentric With the axis of rotation and receiving a discharge liquid from the bowl, the pocket having side walls extending inward to a radial level establishing a maximum depth of liquid for the pocket, said pocket being free of means for introducing fluids thereto from outside said bowl for mixture with said liquid, a stationary takeoff device having a circular outer periphery disposed concentrically about the axis of rotation and extending outward into the pocket, the takeoff device having opposite substantially radial sides and vanes between the sides extending outward to the periphery and defining passages from the periphery into an inward takeoff conduit, the improvement wherein one of said substantially radial sides is reduced in radius to expose portions of the radial faces of the vanes.

2. A centrifuge bowl as described in claim 1 wherein the radial reduction is 540% of the radius of the device.

3. A centrifuge bowl as described in claim 1 wherein said takeoff device further includes at least one annularly extending rib on the other of said radial sides adjacent the periphery thereof for reducing the turbulence of liquid contacted by said exposed portions of the radial faces of the vanes.

4. A centrifuge bowl having a primary separating compartment and a discharge pocket separate from but connected with the primary separating compartment, said bowl receiving material to be centrifuged and separating liquid therefrom for delivery to said pocket, said pocket being free of means for injecting fluids from outside said bowl into said liquid, a paring device in said discharge pocket and disposed concentric with the axis of the bowl, the paring device extending outward into the pocket and comprising a pair of substantially radial side walls and vanes disposed between the side walls, one of the side walls terminating outwardly in a periphery inward of the periphery of the other side walls and the vanes.

References Cited FOREIGN PATENTS 481,711 3/1938 Great Britain.

HENRY T. KLINKSIEK, Primary Examiner.

Claims

1. A CENTRIFUGE BOWL HAVING AN AXIS OF ROTATION, AN ANNULAR INWARDLY FACING POCKET MOUNTED ON THE BOWL CONCENTRIC WITH THE AXIS OF ROTATION AND RECEIVING A DISCHARGE LIQUID FROM THE BOWL, THE POCKET HAVING SIDE WALLS EXTENDING INWARD TO A RADIAL LEVEL ESTABLISHING A MAXIMUM DEPTH OF LIQUID FOR THE POCKET, SAID POCKET BEING FREE OF MEANS FOR INTRODUCING FLUIDS THERETO FROM OUTSIDE SAID BOWL FOR MIXTURE WITH SAID LIQUID, A STATIONARY TAKEOFF DEVIDE HAVING A CIRCULAR OUTER PERIPHERY DISPOSED CONCENTRICALLY ABOUT THE AXIS OF ROTATION AND EXTENDING OUTWARD