US3393863A

US3393863A - Self-cleaning centrifugal separator

Info

Publication number: US3393863A
Application number: US571211A
Authority: US
Inventors: Baram Martin
Original assignee: Individual
Current assignee: Individual
Priority date: 1965-08-14
Filing date: 1966-08-09
Publication date: 1968-07-23
Anticipated expiration: 1985-07-23

Description

July 23, 1968 M. BARAM 3 SELFCLEANING CENTRIFUGAL SEPARATOR Filed Aug. 9; 1966 & 3

v f I 1 z I l I 16 \42 45 mvewron By Men/v EAR/1M ATTORNEY United States Patent 3,393,863 SELF-CLEANING CENTRIFUGAL SEPARATOR Martin Baram, Svanliolmvej 13, Vallensbaek pr., Brondby Strand, Denmark Filed Aug. 9, 1966, Ser. No. 571,211 Claims. (Cl. 233-20) ABSTRACT OF THE DISCLOSURE Self-cleaning centrifugal separator having an upper portion and a lower portion divided by a peripheral ejection slit that is opened and closed by fluid operated means.

The invention concerns a self-cleaning centrifugal separator, particularly for laboratory work, which consists of an upper and a lower part divided by a peripheral ejection slit that can be opened and closed by a hydraulically or pneumatically controlled device.

Existing self-cleaning centrifugal separators that are now utilized for industrial and production purposes employ hydraulic or spring driven meta-l piston shut-off devices that are cumbersome and are not readily adaptable for use with small and high speed rotating centrifuges that are employed for analytical, research, and laboratory purposes. Where it has been suggested that elastic membranes of various shapes may be utilized as shut-off devices for centrifuges, such membranes have never proven to be practicable because the membrane means that are known in the art display various functional drawbacks such as lack of controlability and inadequate wearing qualities. Also, such prior art membranes are not readily replaceable because of the complex structure of the centrifuge. Furthermore, in most cases it has not been possible to ensure satisfactory emptying of the centrifuge because sludge and other similar dirt clog the separate spaced openings in the perpihery of the centrifuge.

An object of the invention is to overcome the disadvantages of prior art self-cleaning devices and to provide a self-cleaning centrifugal separator that is particularly useful for laboratory work but not exclusively limited thereto.

Another object of the invention is to provide a simple centrifuge which includes a hydraulically or pneumatically controlled opening and closing device cooperating with an unbroken peripheral ejection slit.

A further object of the invention is to provide a centrifugal separator with exchangeable parts to adapt the centrifuge to varying purposes.

A still further object of the invention is to provide a centrifugal separator with exchangeable parts that permit a quick and easy replacement of worn parts.

Another vital object of the invention is to provide a centrifugal separator which is furnished with a fluid controlled mernbrane-like shut-ofl device which by virtue of its shape and position closes the ejection slit securely, opens the ejection slit satisfactorily, and helps to prevent clogging of the ejection slit.

The invention shall be explained in more detail in connection with the attached schematic drawing which shows an embodiment of the invention by way of an example which does not limit the invention to its secondary details.

The centrifuge consists of a circular upper part 1 and a circular lower part 2, the latter comprising an outer vessel 3 and an inner vessel 4 between which is defined a circular space 5. A pipe 6 which is coaxial -with the rotation axis is at its lower end in open communication with space 5 through channels 16 which also indicate that pipe6 is screwed onto part 2, thus, channels 16 are segmental openings in a thread. Pipe 6 has at its upper end a flange 14 3,393,863 Patented July 23, 1968 ice which helps to contain any fluid control medium. Space 5 is limited at the upper edges of vessels 4 and 3 by an annular support ring 9 which has one or more spaced apart borings 8 to admit a control fluid medium to an annular space under an elastic membrane 10, said support ring 9 also being furnished with one or more spaced apart borings 11 to let some of the control fluid escape constantly. The peripheral portion of membrane 10 is held in place by a ring 13 secured by screws 16 which are pressed down by screws 15 which connect the upper part 1 with the lower part 2 by means of the support ring 9. Screws 16 determine the height of an ejection slit 12. The membrane 10 is held in place on the axial side by the upper edge of inner vessel 4 which at its lower circular edge is pressed down by said pipe 6 in such a manner that no control fluid can make its way from pipe 6 into the inner vessel 4.

The drawing shows clearly the most important features of the invention whereby that it provides a simple construction, the various parts of which can be exchanged or replaced with ease. Thus, by removing a number of screws 15 the upper part 1, the ring 13 wit-h spacing screws 16, are eased upwardly and half the membrane 10 is thereby loosened, the other half of membrane 10 being relieved by loosening pipe 6, which when entirely removed also releases inner vessel 4. The inner vessel 4 can have various shapes in accordance with the work to be done by the centrifuge, and the same criteria apply to the choice of material which can be stainless steel sheets or other chemically suitable material. Also, membrane 10 can easily be replaced either because it is worn or because different purposes demand different characteristics. The membrane can be of rubber or any suitable plastic material or of a combination of materials. When upper part 1 is removed, the height of slit 12 can be changed by adjusting screws 16. The upper part 1 made of a transparent material such as Plexiglas to observe and control the centrifugation, and it is furnished with an opening 7 through which the centrifugating material can be entered and/ or taken out at will while the centrifuge is rotating.

The centrifuge works in the following manner:

When rotating by means of elements A, fastened to any conventional driving device, a suitable operating medium such as Water is sent through flange 14, pipe 6, channels 16, space 5 and borings 8 to arrive in the annular chamber defined by the under side of membrane 10, and thus a hydrostatic pressure is cen-trifugally generated which forces membrane 10 to expand and to seal ejection slit 12 against upepr part 1. As long as the supply of control fluid compensates for the losses through boring 11, the membrane 10 will be urged tightly against upper part 1, and thus any contents of inner vessel 4 will be held inside the rotating body of the centrifuge. When observation through upper part 1 or other means indicate that the contents in vessel 4 are to be ejected, the supply of controlling fluid in space 5 is either slowed down or stopped. In the first instance of slowing down the controlling fluid, the centrifugated material in vessel 4 will leave very slowly through slit 12 making it possible to stop the ejection at any point by renewing full fluid pressure in space 5, in the other instance of stopping the controlling fluid, the ejection will be sudden and thorough leaving the inner vessel 4 absolutely clean and ready to receive the next batch. All these operations, i.e. filling the inner vessel 4 and emptying it both through opening 7 and ejection slit 12 are practiced while the centrifuge rotates at full speed, and theoretically the centrifuge does not need to be stopped as long as there is work for it to do.

As shown in the drawing, membrane 10 is under fluid pressure to touch part 1; but it is obvious that without fluid pressure in space 5 membrance 10 will be recede away from part 1, and uncover ejection slit 12. Not so obvious is the special feature that the stretching and relaxation of the flexible membrane 10 helps to loosen any obstinate centrifug-ated material which otherwise would resist ejection. This feature is furher enhanced by the fact that the centrifugated material collects inside an unbroken peripheral slit 12.

Experience has shown that the centrifugal separator according to the invention can be made in quite small dimension, e.g. a maximum diameter of 100 mm. at its widest diameter, and it works perfectly at speeds above 10,000 r.p.m.; thus, a new and hitherto unknown tool for laboratory work has been provided. Obviously, the principles of the invention can also be applied to industrial centrifuges of large dimensions.

What is claimed is:

1. Self-cleaning centrifugal separator, particularly for laboratory work, which comprises an upper and a lower part divided by a peripheral ejection slit that can be opened and closed by fluid operated means, said lower part consisting of an inner vessel and an outer relatively spaced and detachable vessel, the outer vessel being furnished with fastening means to engage a driving device, a pipe for the supply of a fluid control medium, said pipe extending coaxially with the axis of rotation through an opening in the upper part and being in fluid conveying communication with the space between said inner and outer vessel, said space at its peripheral end being in fluid conveying communication with an annular elastic shut-off device which in a controllable manner according to fluid pressure in said space alternatively seals and uncovers said peripheral ejection slit between said upper and lower part.

2. Centrifugal separator as in claim 1 wherein the inner vessel has the shape of an outwardly slanting cup.

3. Centrifuge as in claim 1, wherein the inner vessel has the shape of an almost horizontally extending dish.

4. Centrifuge as in claim 1 wherein the upper part consists of a flat transparent disc.

5. Centrifuge as in claim 1, wherein the annular elastic shut-off device consists of a membrane positioned inside an annular element which defines one side of the ejection slit and keeps said space between the inner and the outer vessel in fluid conveying communication with the space under the membrane in such a manner that the membrane when not under the influence of the fluid control medium uncovers the ejection slit and while when under the suflicient pressure of said medium expands said membrane which seals said ejection slit.

References Cited UNITED STATES PATENTS 3,281,068 10/1966 Baram 233--20 HENRY T. KLINKSIEK, Primary Examiner.