US3307780A

US3307780A - Centrifugal separator

Info

Publication number: US3307780A
Application number: US361682A
Authority: US
Inventors: Kompert Paul
Original assignee: Separator AB
Current assignee: Alfa Laval Holdings Amsterdam AB
Priority date: 1963-05-08
Filing date: 1964-04-22
Publication date: 1967-03-07
Anticipated expiration: 1984-03-07
Also published as: DE1432770A1; NL6403136A; DE1432770B2; GB989843A

Description

INVENTOR.

P. KOMPERT CENTR I FUGAL S EPARATOR Pau/ Kampgr/ Filed April 22, 1964 March 7, 1967 United States Patent 3,307,780 CENTRIFUGAL SEPARATOR Paul Kompert, Stockholm, Sweden, assignor to Aktiebolaget Separator, Stockholm, Sweden, a corporation of Sweden Filed Apr. 22, 1964, Ser. No. 361,682 Claims priority, application Sweden, May 8, 1963, 5,047/63 6 Claims. (Cl. 233-45) The present invention relates to centrifugal separators of the type provided with a distributor disk in the separation chamber and with a hermetically closed inlet for a liquid, which inlet opens on one side of the disk and communicates with the other side of the disk. Separators of this type include separators with hermetically closed outlets, self-opening sludge-separators and separators which discharge via regulating disks or paring members. In separators of this kind, a cushion of air or other gases is often formed between the above-mentioned inlet orifice and the distributor disk. As more air is fed to the abovementioned air cushion, the latter is compressed so that a pressure will prevail in the inlet, thereby making the pumping in of more liquid difficult or impossible. In an effort to solve this problem, a hole has been formed at the center of the distributor disk so that air from the inlet can pass through the disk to its other side and be discharged through the outlet of the separator or possibly through an open communication with the surrounding atmosphere. However, if all the air is discharged in this way from the inlet, the liquid to be separated can pass through the hole and mix with the previously separated liquid and thus pollute the latter.

According to the present invention, the above-mentioned drawback is avoided by arranging the inlet to open into the separation chamber at a distance from the axis of rotation and by providing a channel which, within the central part of the distributor disk, forms an additional communication between both sides of the disk, a part of this channel being located at a shorter distance from the axis of rotation than the channel orifice which is located on the side of the disk remote from the inlet. In this way, due to the air compressed in the channel, the latter forms a stoppage for the liquid coming from the inlet so that said liquid cannot pass through the channel and penetrate into the separation chamber on the other side of the distributor disk, as long as the liquid is not subjected to an excessive feeding-in pressure. This stoppage, which depends upon the radial distance between said channel orifice and the axis of rotation, can be made still more effective by inserting in the channel a springloaded valve adapted to open for a flow of air in the direction towards the channel orifice under a predetermined high pressure.

When the liquid level at the orifice of the inlet is displaced towards the axis of rotation, the air enclosed in the channel is compressed. The highest pressure is reached when said liquid level reaches the axis of rotation. Therefore, a part of the channel is arranged to pass through the rotation center or axis of the separator, since the required stoppage is most effective in this case.

The present invention is especially useful in self-opening sludge-separators or fully hermetic separators. In such separators (in view of the liquid-pressure balance in the separation chamber), the inlet should generally open into the separating chamber at a longer distance from the axis of rotation than said channel orifice. In this way, the latter orifice as well as the inlet orifice are covered by liquid so that the required cushion of compressed air is formed in the channel.

The inlet opens into the separation chamber preferably by means of one or more radial channels. Air will usu- 3,307,786 Patented Mar. 7, 1967 ally be carried along with the liquid supplied through the inlet; and in order to prevent this air from remaining in the radial channels, the total cross sectional area of the latter is made about as large as the cross sectional area of the inlet. Thus, any air bubbles are conveyed by the flowing liquid to the outlet orifices of the radial channels.

The radial channels are preferably arranged in a'disk which is perpendicular to the axis of rotation. This disk may serve at the same time as a nut for fastening the separator rotor onto its drive shaft.

Since the periphery of the disk will be covered by liquid, air-filled chambers will be formed on both sides of the disk. In order to achieve a pressure balance between both of these chambers, the disk is provided with one or more channels which ensure communication between both sides of the disk.

The invention is described more in detail in the following, reference being made to the accompanying drawing Which shows, by way of example, a separator embodying the present invention. In the drawing:

FIG. 1 is a vertical axial sectional view of part of the separator, which in this example is of the fully hermetic type, and

FIG. 2 is a sectional view along line II-II in FIG. 1.

Referring to the drawing, the centrifugal separator there shown comprises a hollow rotor 1 and a hollow drive shaft 2 which is fastened to the rotor by means of a disk-shaped nut 3. The shaft 2 is driven from any suitable power source (not shown) and rotates the rotor 1 about a central vertical axis A. Liquid to be separated is supplied through a central channel 4 in the hollow shaft 2, this channel thus forming an inlet of the rotor. A conical distributor disk 5 rests on the bottom of the rotor and defines therewith a sub-chamber 1a at one side of the disk (the lower side) and a main separating chamber 1b at the other side of this disk (the upper side). The chambers 14 and 1b have communication with each other through holes 6 in the distributor disk 5, these holes allowing the incoming liquid to flow upwardly from subcham-ber 1a to the main separating chamber 1b. A conventional set of spaced conical disks is located in the main chamber 1b where it is seated on the distributor disk 5, the lowermost disk of this set being shown at 7a and the disk set generally being shown in phantom at 7. Radial impeller veins 8 are located at the inner portion of the sub-chamber 1a.

The nut 3 has a hollow central portion to which the inlet channel 4 leads upwardly. The nut also has six radial passages 9 through which its hollow central portion (and therefore the rotor inlet 4) communicates with the sub-chamber 1a. The radial passages 9 have outlet orifieces 9a located at a substantial distance from the rotation axis A. In the normal operation of the separator, these outlet orifices 9a are covered by liquid, the level of which is designated by reference numeral 10. Radially within the level 10 is a space 11 located between the top of nut 3 and the undersurface of distributor disk 5, this space being filled with air at a pressure which is determined by the radial position of the level 10. A channel 12 extends through the nut 3 from top to bottom and serves to balance the air pressure above and below the nut.

The underside of the distributor disk 5 is provided with a central axial hole 13 above the space 11. A radial channel 14 in distributor disk 5 extends outwardly from the hole 13 and opens into the main separating chamber 1b above the disk 5. Clarified liquid (constituting the lighter component separated in chamber 1b) settles in the channel 14 to a level indicated at 15. The positions of the

levels

10 and 15 are determined by the pressure balance between the liquids on the opposite faces or sides the conventional manner through respective outlets (not shown).

In the operation of the separator, the liquid to be separated is pumped in through the channel 4 against a pres- :sure which is determined by the pressure drop in the sepa- ;rator. router ends 9a of the channels 9 and turn off radially inwardly toward the chamber 11 in which they gather. Thus, the air quantity in the chamber 11 increases at the Air bubbles carried along by the liquid reach the :same time as the air pressure in it rises. When the air pressure increases, the levels 10 and are displaced radially outward until the level 15 reaches the radially outer end of the channel 14. The outlet orifices 9a of the channels 9 must be located so that, under the above conditions, they are still covered by liquid. As more air is collected in the chamber 11, a corresponding quantity of air is released from the outlet orifice of the channel 14 and discharged through the separator outlet from chamber 1b together with clarified, separated liquid.

The air cushion enclosed in the chamber 11 prevents the passage of feed liquid from the inlet 4 through the channel 14 and mixing of this liquid with clarified, separated liquid in chamber 1b, in case liquid fed through the inlet 4 is free of air during a certain period of time.

It will be apparent that the nut 3 constitutes in effect a means in the rotor 1 forming an hermetically closed feed passage 9 leading from inlet 4 and opening into the subchamber 1a at a distance from the rotation axis A.

I claim:

1. In a centrifugal separator, the combination of a hollow centrifugal rotor adapted to be rotated about a central axis, a distributor disk in the rotor defining therewith a main separating chamber at one side of the disk and a sub-chamber at the other side of the disk, said chambers having a communication with each other for flow of a liquid from said sub-chamber to said main chamber, said 51 ,5 having a central portion forming a channel constituting an additional communication between said chambers, said channel having an outlet orifice opening into said separating chamber and also having a part opening into the sub-chamber and located nearer said rotation axis than is said orifice, the rotor having an inlet for said liquid, and means in the rotor forming an hermetically closed feed passage leading from said inlet and opening into said sub-chamber at a distance from said axis which is greater than the distance of said outlet orifice from the aX1S.

2. A separator according to claim 1, in which said part of the channel is located on said rotation axis.

3. A separator according to claim 1, in which said feed passage extends radially outward from said inlet.

4. A separator according to claim 1, in which said feed passage extends radially outward from said inlet, said means forming at least one additional feed passage leading radially from said inlet and opening into the sub-chamber at a distance from said axis, the total cross-sectional area of said radial feed passages being about equal to the cross-sectional area of said inlet.

5. A separator according to claim 1, in which said passage forming means comprise a second disk disposed perpendicularly to said axis and having a central portion to which said inlet leads.

6. A separator according to claim 1, in which said passage forming means comprise a second disk disposed perpendicularly to said axis and having a central portion to which said inlet leads, said second disk having a channel forming a communication between opposite sides of said second disk.

References Cited by the Examiner UNITED STATES PATENTS 2,087,630 7/1937 Schelbeck 23346 XR 2,214,831 9/1940 Hall 23327 2,717,119 9/1955 Jones 23321 2,985,361 5/1961 Smith 233 3,095,371 6/1963 Fitzsimrnons 233-45 M. CARY NELSON, Primary Examiner.

HENRY T. KLINKSIEK, Examiner.

Claims

1. IN A CENTRIFUGAL SEPARATOR, THE COMBINATION OF A HOLLOW CENTRIFUGAL ROTOR ADAPTED TO BE ROTATED ABOUT A CENTRAL AXIS, A DISTRIBUTOR DISK IN THE ROTOR DEFINING THEREWITH A MAIN SEPARATING CHAMBER AT ONE SIDE OF THE DISK AND A SUB-CHAMBER AT THE OTHER SIDE OF THE DISK, SAID CHAMBERS HAVING A COMMUNICATION WITH EACH OTHER FOR FLOW OF A LIQUID FROM SAID SUB-CHAMBER TO SAID MAIN CHAMBER, SAID DISK HAVING A CENTRAL PORTION FORMING A CHANNEL CONSTITUTING AN ADDITIONAL COMMUNICATION BETWEEN SAID CHAMBERS, SAID CHANNEL HAVING AN OUTLET ORIFICE OPENING INTO SAID SEPARATING CHAMBER AND ALSO HAVING A PART OPENING INTO THE SUB-CHAMBER AND LOCATED NEARER SAID ROTATION AXIS THAN IS SAID ORIFICE, THE ROTOR HAVING AN INLET FOR SAID