US2688436A - Extensible gasket for centrifuge bowls - Google Patents

Description

Fig. 3

INVENTOR.

Sept. 7, 1954 R. M. MELAVEN EXTENSIBLE GASKET FOR CENTRIFUGE BOWLS Filed Sept. 11, 1952 Ralph M. Melav BY K fl ATTORNEY Fig; 1

F l'g. 2

Patented Sept. 7, 1954 EXTENSIBLE GASKET FOR CENTRI'FUGE BOWLS Ralph M. Melaven, Highland, Ind., assignor to Standard Oil Company, Chicago, 111., a corporation of Indiana Application September 11, 1952, Serial No. 309,053

1 Claim.

This invention relates to centrifugal separating. apparatus and the like. More particularly, it relates to a centrifugal separator embodying a novel extensible ring gasket to prevent leakage through annular openings during high speed operation.

Centrifugal separating equipment is employed in many industries to effect a physical separation between liquids of different specific gravity. Such equipment ordinarily embodies a bowl which is separable, top from the bottom. And it has been a real problem to properly seal the annular mating surfaces of these two bowl sections,

particularly in those industries handling liquids of high specific gravity. Unlike most sealing problems requiring a gasket, no mechanical pres sure or other means for clamping the ring in place is available; centrifugal force must be relied upon entirely to maintain the closure. Various gaskets or packings have been employed but none has been completely satisfactory. Such gaskets, tobe effective, must be extensible yet sufficiently heavy to remain snug against an annular opening during operation of the apparatus. Since the heaviest liquid material will always migrate to the outside of a rotating centrifuge, it is essential that the sealing ring be heavier than any material being acted upon.

A primary object of the present'invention is to provide an improved, extensible sealing ring for centrifugal separating equipment. and the like which will prevent leakage through annular openings during high speed operation. A further object is to provide a yieldable sealing ring which when acted upon by centrifugal force modifies its normal shape to conform to and completely seal off the annular juncture of the upper and lower bowl sections of a centrifugal separating device. An additional object is to provide a yieldable and extensible sealing ring which is heavier than the heaviest liquid undergoing separation in a centrifugal device. These and additional objects will be apparent from the following detailed description of the present invention when considered in conjunction with the attached drawings.

In the drawings, Fig. 1 is a partial elevation view of a conventional centrifuge employed in the separation of sludge from acid treated petroleum oil with all non-rotary parts removed and with portions of the bowl structure broken away to illustrate the relationship of the novel sealing ring to the equipment as a whole.

Fig. 2 is an enlarged view of that portion of the centrifuge contiguous to the sealing ring shown in Fig. 1.

Fig. 3 is essentially the same View as Fig. 2. but with the sealing ring distorted, substantially as it would appear under the influence of centrifugal force.

Inasmuch as the various elements of the centrifugal equipment to which the sealing ring of the present invention is applicable are well-known to those skilled in the art, only those portions of the equipment necessary to completely illustrate the present invention are shown in the drawing or will be described in detail. A centrifuge of particular design is shown in the drawings but the invention is in no way limited to equipment of such design but is adapted for use in any centrifugal separating device having sealing problems of the general type described.

In Fig. 1, the bowl of the centrifuge it is surmounted by inlet H and oil outlet l2, concentric thereto. The sludge outlet is aperture ma. Bowl structure lil comprises upper bowl section I3 and.

lower bowl section Hi which are held firmly to gether by annular ring it. Ring 55 is screwed on to section it by means of threads It. The upper portion of ring l5 forces down on section [3 at E! to cause the two bowl sections to be mated annularly at l8. Sealing gasket or ring [9 is juxtaposed to annular juncture E3 of the two bowl sections within annular space 20. Annular space 2.9 is formed by cut-outs in the upper and lower bowl sections and retaining rim or bracket 2| extending upward from the lower bowl section.

Sealing. ring it comprises an extensible doughnut-shaped gasket filled with a liquid 59a heavier than any liquid being acted upon by the centrifuge. The various other embodiments of the centrifugal device shown, e. g. the separating disks 22, etc. are conventional and should not be considered, per se, a part of the present invention.

Fig. 3 illustrates the manner in whichthe ring is distorted by the influence of centrifugal force to conform to the shape of the outer structure of annular space 20 and to form a complete circumferential seal so that no liquid may pass through juncture Hi.

It is necessary that the liquid l9a within the yieldable doughnut I9 be of high specific gravity; specifically, it must be higher than the heaviest liquid encountered in a given centrifugal separation. If, for example, water were contained within the ring during the centrifugal separation of acid sludge from sour oil, the sludge containing a substantial amount of sulfuric acid and having an overall specific gravity greater than water would displace the sealing ring from the outer wall of annular space 23 and leakage could occur at juncture 18. In accordance herewith, it is preferred that the ring contain mercury. Other suitable liquids having a high specific gravity, e. g. carbon tetrachloride, glycerin, etc. may likewise be employed. Mixtures of such liquids may also be employed. Whereas the specific gravity of the liquid is preferably substantially greater than 1 it should be understood that it need only be greater than the heaviest liquid being acted upon in the centrifuge.

It is preferred, when the sealing ring is to be in contact with acid of varying strengths as well as hydrocarbon oils, e. g. in removal of acid sludge from oil, that it be composed of a chemically inert material which is insoluble in most organic solvents. The polyfluoroethylene plastics, e. g. Teflon, polytetrafluoroethylene resin-a product of E. I. du Font, and Kel-F, polychlorotrifluoroethylene resin-a product of The M. W. Kellogg Co., are particularly suitable and meet the requirements of such a gasket. Where the centrifuge is employed to separate liquids which do not have a deleterious effect upon the ring, natural or synthetic rubber or other suitable material, e. g. Neoprene, may be employed. Polyethylene has been found to be both extensible and resistant to most chemicals and may be employed for the purpose described.

Rings of the type employed in accordance herewith are readily prepared by molding or casting in much the same way as for example, automobile inner tubes and the like. The heavy liquid, e. g. mercury, may be introduced through a suitable aperture which is then sealed. Although described with particular reference to a ring shaped gasket, it should be understood that it is within the scope of the invention to employ various other shapes of mercury-filled yieldable gaskets for sealing openings which are other than circumferential in nature. Thus, short lengths of such extensible liquid filled gaskets may be employed. A use for such a gasket, apart from a centrifuge, is in a device accelerating linearly at a high rate, in which it is desired to prevent flow of liquid during acceleration but to permit same upon attaining a uniform velocity.

Although the present invention is described with particular reference to the use of a liquidfilled gasket in conjunction with circumferential metal to metal mating surfaces, as shown in the drawings, it should be understood that such a sealing ring or gasket is suitable for use in accordance with any sealing problem encountered in the operation of centrifugal equipment or the like. Thus, for example, in certain industries it is desirable to introduce washing liquid to the centrifuge rather than removing the top section of the bowl to clean same. In such industries, e. g. the dairy industry, it is common to employ centrifuges similar to that shown in the drawing but which, rather than having metal to metal contact between the upper and lower sections of the bowl (as indicated by juncture I8), embody a system of annular openings and support members or spacers at this location. These annular openings must be sealed during the separating cycle, but open during washing. This is achieved by operating at a higher speed during separation than while washing. The ring is thus extended to close 01f the annular ports during separation but not during the washing cycle. The sealing ring described herein is very useful in conjunction with such equipment. U. S. 2,473,967, U. S. 2,555,542, U. S. 2,482,570, are all directed to centrifugal equipment employed in the dairy industry and more particularly directed to expansible sealing rings for use therein. The sealing ring of the present invention may be substituted for those shown in the above patents with excellent results.

Having thus described the present invention, what I claim as novel and desire to protect by Letters Patent, is as follows:

In combination with an apparatus embodying upper and lower bowl sections in which centrifugal force may be generated to effect a separation of a sulfuric acid sludge from sulfuric acid treated oil, means for preventing undesired leakage of such liquids through the annular juncture between said upper and lower bowl sections in such apparatus during operation thereof which means comprises an extensible hollow sealing gasket comprising a ring of polyfluoroethylene resin filled with mercury, said ring being juxtaposed inwardly of said annular juncture.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 829,546 Schou Aug. 28, 1906 2,139,715 Bergner Dec. 13, 1938 2,461,655 Noble Feb. 15, 1949 2,597,976 Cousins May 27, 1952 FOREIGN PATENTS Number Country Date 528,359 Great Britain Oct. 28, 1940

Images