US2719668A

US2719668A - Centrifugal bowl

Info

Publication number: US2719668A
Application number: US375334A
Authority: US
Inventors: Bergner Nore Einar
Original assignee: Separator AB
Current assignee: Alfa Laval Holdings Amsterdam AB
Priority date: 1952-09-04
Filing date: 1953-08-20
Publication date: 1955-10-04
Anticipated expiration: 1972-10-04
Also published as: DE1040459B; GB749786A; NL181147B; NL96812C

Description

Oct. 4, 1955 N. E. BERGNER CENTRIFUGAL BOWL Filed Aug. 20,.1953

INVENTOR. fife/"e znar Beer W. Wm #mM United States Patent 2,719,668 7 CENTRIFUGAL BOWL Nore Einar Bergner, Stockholm, Sweden, assignor to Aktiebolaget Separator, Stockholm, Sweden, a corporation of Sweden Application August 20, 1953, Serial No. 375,334 Claims priority, application Sweden September 4, 1952 12 Claims. (Cl. 233.32)

This invention relates to centrifugal separators and more particularly to an improved centrifugal bowl for separating a feed into at least two constituents of different specific gravities.

The centrifugal bowl of the present invention has a separating chamber which preferably is of great length or axial extent as compared to its diameter. 'In any case, the bowl is characterized by having feed channels'in'one end of the separating chamber for admitting the material to be separated, these feed channels opening into the separating chamber at its periphery and serving to impart rotary movement to the feed material, while in the other end of the separating chamber are substantially radial channels or flow spaces; and at least one discharge opening is arranged in the central part of the separating chamber. 7

For a better understanding of the invention, reference may be had to the accompanying drawing, in which the single illustration is a vertical sectional view, partly schematic, of apreferred form of the new bowl.

Referring to the drawing, the numeral 1 designates a centrifugal bowl mounted on a hollow drive shaft 1a which forms a feed channel fordelivering the material to be separated into .the separating chamber 2. The flow of the 1 feed from channel 1b to chamber 2 is' by way of a number of feed channels 3 arranged more or less perpendicularly to the shaft of the centrifugal bowl .and opening into the separating chamber 2 at one endof .the bowl, the feed end. ,The channels 3 may bei'formed by means including radial vanes 3a underlyinga central baffle disc 3b. At the other end of the bowl, likewise in the separating chamber 2 are substantially radial channels 4. The centrifugal bowl is provided with two concentrically arranged discharge devices or

channels

5 and 6, and the discharge openings formed by these channels in the centrifugal bowl are located in-the central .part of the separating chamber. Theseparating chamber is provided at its periphery with an enlargement forming a sludge space or chamber 7 for:collection of separated sludge; and in the wall of the centrifugal bowl are sludge outlets 8, such as nozzles or the like, which preferably are directed backwards with respect to the direction of rotation of the bowl. The separated components may be collected in the usual manner in receiving chambers formed by the

stationary covers

9, 10 and 11.'

It will be observed that the separating chamber 2 has a central vertical axis corresponding to the axis of rotation of the hollow drive shaft 1a of the bowl. This chamber also has opposed, axially spaced ends formed by disc 3b and the top of the bowl, respectively. The discharge openings 5a and 6a, as shown, are located at a shorter distance from the chamber end 3b at which the inlet channels 3 are located than from the other end at which the channels 4 are located.

The material to be separated is preferably fed to the rotating centrifugal bowl 1 under pressure, and the feed channel 1b in the shaft should therefore be directly connected to its stationary feed line by means of a sealing arrangement of conventional form (not shown). In the channels 3 ,a rotational movement is imparted to the feed material which then flows in an axial direction throughthe separating chamber substantially following its outer boundary surface. The heavier particles in the material are thereby separated out and slide along this outer boundary surface to the sludge chamber ,7, from which they are then discharged through the nozzles 8. The light component, and the heavier particles which are more difiicult to separate, continue in an axial direction to the other end of the bowl where. they are forced through the channels .4 arranged therein (which may be formed, for example, by means of radially directed vanes 4a) and inward toward the central. part of .the separating chamber, and then flow downward along the inner boundary. surface of the separating chamber in an axial direction toward the openings of the discharge channels Sand 6. This material is finally discharged from the separating chamber through the

discharge channels

5 and 6, which may be formed by concentric tubes.

It is to be noted that the material being separated does not to any appreciable extent pass through-the separating chamber 2 directly from the mouths of the feed channels 3 to the mouths .of the

discharge channels

5 and 6, but mainly follows the arrows indicated on the drawing. If the material should take the shortest way through the separating chamber, it would slide because there are no vanes, blades or the like in this part of the separating chamber. Such a sliding movement causes an extraordinarily high counter-pressure which increases rapidly according to the throughput rate. Owing to the conveying effect .of the channels 3 arranged in the feed end of ;the separating chamber, the material does .not take the shortest waythrough .this chamber but instead passes axially, in the manner described :above, first in one direction along the outer boundary surface of the separating chamber .and then ;in the .opposite direction along the inner boundary surface of .the separating chamber. Thematerial is thus subjected to an extremely effective separation, partly .due to its long path through the separating chamber .and partly because this path in general is situated in the .outer part of the separating chamber, which from the .point .of .view of separation is the most eflicient part. Due to this flow path, the diameter of the separating chamber may be very small, whereby the centrifugal bowl may .be operated at a relatively high speed :of :rotation, which is -of importance because the smaller the diameter, the greater the acceleration will be for given stresses in the centrifugal bowl. The channels 4 in the upper part of the separating chamber allow the material to move inward at :a low counter-pressure, since they act to prevent sliding of the material relative to the bowl.

If the sludge particles vary considerably in size, the smallest particles (i. e., those which are most difiicult to separate) will be discharged through the outlet 5 together with the liquid component. By sliding from channel 5 to channel 6, however, a lighter liquid can also be separated off, the purified liquid thus discharging through channel 6 and the lighter sludge through channel 5. Since the sliding, as previously mentioned, causes a considerable counter-pressure, the amount which discharges through the inner channel 6 will be smaller than that discharging through the outer channel 5.

From the above description of the operation of the centrifugal bowl, it is clear that the discharge openings 5a and 6a for the lighter components located in the central part of the centrifugal bowl may be placed quite near the feed end of the centrifugal bowl, and yet there is no risk of the feed material taking the shortest path from the feed channels 3, which open at the periphery of the separating chamber, to the discharge openings 5a and 6a. Thus, a very advantageous elongation of the flow path of the material through the separating chamber is obtained.

' The centrifugal bowl here illustrated is to be regarded only as an example of the present invention and can therefore be modified. In case of small sludge quantities to be separated, the sludge outlets 8 (and possibly also the enlargement 7 serving as a sludge chamber) may be eliminated. Also, the sludge outlets 8 and the sludge chamber '7 may be located at a greater or smaller distance from the feed end of the centrifugal bowl than that shown on the drawing.

The substantially radial channels 4 at the other end of the centrifugal bowl may consist of the spaces between radially directed vanes, blades or the like, which are shown at 4a It is also to be noted that the shaft 1a of the centrifugal bowl of the present invention need not be driven, since rotary motion in the separating chamber can be imparted to the material in the same manner as in a cyclone. Thus, the necessary rotation of the feed material may be effected, without rotating the bowl 1, by simply arranging the feed channels 3 so that they open into chamber 2 substantially tangentially, as is Well-known and conventional in cyclones.

It is further pointed out that the separator may also be used for separation of two liquid components from one another, in that the lighter liquid component is discharged through outlet 6, and the other liquid component through outlet 5, whereas the sludge, as mentioned above, either is discharged through the nozzle openings 8 or is collected in the sludge chamber 7. On the otherhand, more than two liquid components may be taken out through a corresponding number of concentric discharge openings in the central portion of the separating chamber. The nozzle openings at the periphery also may be used as outlets for the heaviest liquid component instead of being used as sludge outlets, provided that the material being separated contains no heavy sludge.

I claim:

1. In a centrifugal bowl forming a separating chamber having a central axis and opposed, axially-spaced ends, the combination of means forming an inlet channel for the feed material at one end of the chamber, said channel opening into the separating chamber at its periphery and being operable to impart a rotary movement to the feed material, means forming substantially radial channels in said chamber at the other end thereof and in which material from said inlet channel, after traversing the chamber 3. A centrifugal bowl according to claim 1, in which said means forming the inlet channel include generally radial vanes forming a plurality of inlet channels, the bowl also having externally thereof a central hollow shaft forming a feed channel leading directly to said inlet channels.

4. A centrifugal bowl according to claim 1, comprising also a central shaft mounting the bowl for rotation on said axis.

5. A centrifugal bowl according to claim 1, in which said discharge opening is located at a shorter distance from said first end of the chamber than from the other end thereof.

6. A centrifugal bowl according to claim '1, in which the separating chamber intermediate its ends is provided with an enlargement at its periphery forming a sludge space for collecting sludge separated from the feed material.

7. A centrifugal bowl according to claim 1, in which the separating chamber intermediate its ends is provided with an enlargement at its periphery forming a sludge space for collecting sludge separated from the feed material, said sludge space being located near said other end of the separating chamber.

8. A centrifugal bowl according to claim 1, in which the separating chamber is provided with sludge outlets in the peripheral wall of the bowl.

9. A centrifugal bowl according to claim 1, in which the separating chamber is provided with sludge outlets in the peripheral wall of the bowl, said sludge outlets being located near said other end of the separating chamber.

10. A centrifugal bowl according to claim 1, in which a the separating chamber intermediate its ends is provided with an enlargement at its periphery forming a sludge space for collecting sludge separated from the feed material, said sludge space being located near said other end of the separating chamber, there being sludge outlets in the peripheral part of said sludge space.

11. A centrifugal bowl according to claim 1, comprising also a second discharge device in the bowl forming a second discharge opening in the central part of said chamber but at a dilferent radius than the first dis charge opening.

' 12. A centrifugal bowl according to claim 1, in which said discharge device is a central tube in the bowl,,the bowl also having a second discharge tube concentric with the first and forming a second discharge opening.

References Cited in the file of this patent UNITED STATES PATENTS 1,870,113 Hawkins et a1. Aug. 2, 1932 2,422,882 Bramley June 24, 1947 FOREIGN PATENTS 111,848 Germany July 16, 1900