US2089123A - Centrifugal separator - Google Patents

Description

Aug. 3, 1937. 1.. D. JONES I CENTRIFUGAL SEPARATOR Filed April 22, 1936 INVENTOR. LEO D. J oHEs BY a. M

A TTORNEY Patented Aug. 3, 1937 UNITED STATES CENTRIFUGAL SEPARATOB Leo D. Jones, Philadelphia, Pa., assig'nor to The Sharples Specialty Company. Philadelphia, Pa, a corporation of Delaware Application April :2, 1936, sci-in No. 75,668 4 Claims. (01. zit-as) The present invention relates to the art of centrifugal separators and is concerned with the development of a centrifugal separator adapted to effect emcient separation from a liquid of I a viscous material of lower specific gravity than said liquid. The invention was conceived in connection with the development of a centrifugal separator capable of continuously discharging from an imperiorate centrifugal rotor a viscous 1. material stratified from a liquid within said rotor and which is of such a viscous or dry consistency as to present serious difficulty in connection with attempts to discharge such material under liquid balance from the liquid from II which it has been stratified. In order to effect continuous discharge of material of this consistency, the inertia of the rotating material within the rotor is taken advantage of to effect dislodgment of that material from the rotor. To go this end, a stationary inertia dislodging means, such as a skimming nozzle or a dislodging knife,

is used.

In the particulars discussed above, and in the general design of the centrifugal rotor of the 25 present invention, the invention resembles the invention of my prior application Serial No. 751,336,

.! filed November 3, 1934 for Method and apparatus for separating wax from oil. The present invention was conceived and reduced to practice Mas a solution of problems arising in connection with the use of a centrifugal separator designed in accordance with my prior application above identified.

In a general way, it may be said that the pres- 36 cut invention consists in improvements over the prior application designed to effect continuous and steady discharge of the stratified viscous ma-' terial under the influence of the dislodging tool. Specific difllculties which have been overcome 40 and whose solution consutute most important features of the invention can best be understood after a general discussion of the type of centrifugal separator involved and its method of operation.

Referring to the attached drawing for an illustration of the invention, Fig. l of that drawing constitutes a central longitudinal cross-section through the centrifugal separator of the invention and I Fig. 2 is a transverse cross-section taken on the line 2-2 of Fig. l.

The invention was conceived as the solution of the problem of separating waxes of various consistencies from petroleum stocks diluted with a solvent adapted to render such stocks of higher specificfg'ra'vity than the precipitated wax, and will be described in connection with a separating problem of this character.-

Referring to the drawing by reference characters, the numeral l designates a centrifugal rotor. The mixture to be subjected to a centrifugal separating operation, such as a suspension of wax in a solution of petroleum stock in a solvent of high specific gravity, is fed to the centrifugal rotor by means of a feed nozzle ll communicating with a central tube It constituting a part of the centrifugal rotor. The mixture to be centrifuged passes from the central tube i2 into the main body of the rotor through radially extending passages If. The rotor contains a plul5 rality of stratifying plates l4 adapted to facilitate centrifugal separation of constituents of the mixture, these stratifying plates being in the form of nested frustro-conical discs in the form of the invention illustrated.

It isto be noted that the discharge i3 deliver the mixture to be subjected to centrifugation to a zone of the rotor within the inner termini of the stratifying plates It. The purpose of delivering the mixture to this zone is to effect subsidence of a large part of the lighter and more viscous material without passing such material to the zone occupied by the stratifying plates. As explained in my prior application identified above. this feature of design makes it possible to avoid rapid cloggage of the space between the stratifying plates by the viscous mate- "rial and has important advantages in connection with an operation such as the separation of wax from a'heavyoii solution.

The rotor is provided with a frustro-conical dividing wall It, and the heavier material stratified as the outer layer within the rotor is continuously discharged around the outer. edge of this dividing wall and through passages it 10- 4o cated between this dividing wall and the upper part ll of the rotor. This liquid eiliuent is continuously discharged into the-receiving cover I. of the centrifuge. A dislodging tool in the form of a skimming nozzle I. which is reclprocable toward and away from the stratum of viscous lighter material occupying the inner radial zone U of the material stratified within the rotor is provided for discharge of this viscous material. The features of the machine design discussed above are described and claimed in my prior applica- 7 tion referred to above, and constitute no part of the present invention. A consideration of the mode of operation of this machincintheseparationofwaxirom'aheavy 66 oil solution of a centrifugal separator incorporating these features of design will illustrate the background of the present invention and the advantages attained by the practice of the invention. In the separation of wax from a heavy oil solution, the rotor is first set in operation and the chilled waxy oil solution is fed to the stratifying section of the rotor through the feed nozzle I I and the central tube i2 with its radiating passages I3. At this stage of the operation, the skimming nozzle I9 is set at a position radially inward of its normal operative skimming position. As the mixture accumulates in the rotor, the heavier oil solution will be stratified from the wax and flow outwardly, around the frustro-conical dividing wall l5 and through the passages l5 into the liquid receiving cover II.' The layer of wax gradually accumulates within the portion of the rotor lying inwardly of the inner termini of the discs l4. When this layer of wax accumulates to the desired depth, the skimming nozzle I! is slowly moved outwardly into the inner part of the zone occupied by the wax layer stratified within the rotor. The nozzle is should be moved outwardly until a continuous and uniform discharge of wax is obtained. Such an operation is obtainable in connection with the dewaxins of certain types of oils, 'notably cylinder stocks, but great difficulty is encountered in attempts to obtain the desired uniformity of wax discharge with other types of oils, notably oils containing fine and granular waxes, such as those which occur in distillates of intermediate gravity and viscosity.

When working with stocks containing fine and granular waxes, as the nozzle is is moved into the wax layer, wax is initially discharged through that nozzle. As the nozzle is gradually moved further outwardly toward the point at which the most satisfactory operation should be obtained with respect to the thickness of the wax layer and relative freedom of wax from entrained oil, however, the wax discharge suddenly becomes very thin due to the discharge of heavy oil solution therewith and if the nozzle is moved inwardly to reduce the quantity of oil picked up by the nozzle and to thicken the wax, the discharge of the wax suddenly ceases almost entirely and the wax stratum within the rotor moves outwardly largely into the zone occupied by the stratifying plates ll, leaving the skimming nozzle high and dry.

If now the nozzle is is moved outwardly until it again reaches the wax layer, satisfactory wax discharge can be obtained for a while, but after a short period of operation, the wax becomes suddenly very much thinner again and this can be temporarily corrected by movement of the nozzle inwardly. The entire undesired sequence must soon be repeated in order to obtain continued operation of the process, however.

The object of the present invention has been improve upon the features of design of a centrifugal rotor of the character described above in such a manner as to afford uniform and continuous discharge of the viscous and lighter eiiiuent, such as the wax of the above illustration, and to avoid the dimculties discussed above.

This object is accomplished, in the practice of the invention, by the provision of means 2. for maintaining the lighter subsided material which occupies the portion of the rotor lying inwardly of the inner termini of the stratifying plates at a speed of rotation substantially the same as the speed of rotation of the rotor. These means constitute, in the form of the invention illustrated.

"rial.

accelerator structure in the form of a plurality of radially extending webs or wings which may be formed integrally with the central tube l2 and extend radially from this central tube to the inner termini of the stratifying plates I. These wings contain portions in the form of webs 2i extending a substantial distance longitudinally of the rotor and occupying the full depth of the inner wax stratum within the rotor. These webs, at their outer radial extremities, are preferably enlarged to form ribs 22, which also assist'in maintaining the viscous material at approximately the speed of bowl rotation and which extend throughout substantially the entire longitudinal zone of the rotor occupied by the viscous mate- The zone of the rotor adjacent the skimming nozzle I9 is of course left free of accelerator structure in order to afford provision for unobstructed movement of the skimming nozzle. The upper ends of the ribs 22 are preferably connected together by means of an annular frustroconical rigidifying disc 23. The outer radial extremities of the ribs 22 preferably abut the inner radial extremities of the stratifying plates I4 and tend to center these stratifying plates within the rotor. One of these ribs is preferably provided with a key 24, as illustrated, which enters into slots formed in the stratifying plates and thus insures the rotation of these plates at the same speed as the rotor.

It has been found that the provision of the simple expedient described above in conjunction with the dislodging tool 19 serves to maintain the wax stratum at substantially the speed of rotation of the rotor and to avoid the diiiiculties discussed above in connection with the continuous discharge of fine and granular waxes.

Modifications will be obvious to those skilled in the art and I do not therefore wish to be limited except by the scope of the sub-joined claims.

I claim:

1. A centrifugal separator comprising an imperforate rotor in which subsidence of a mixture of liquid and solids of lower specific gravity than said liquid is adapted to,take place under the influence of centrifugal force, and means for feeding a mixture of liquid and solids to the rotor, said rotor comprising a main body portion, means for directing a mixture fed to the rotor into a central unobstructed part of said main body portion provided with radially extending accelerator members, and a series of closely spaced frustro-conical discs having their inner circumferential termini radially a substantial distance without said zone of feed, whereby to afford a substantially unobstructed subsidence zone provided with accelerator members within which the major portion of the solids of said mixture is adapted to be stratified from the liquid content of the mixture and a radially outer disc zone within which residual solids which flow outwardly with liquid from said unobstructed subsidence zone are adapted to be collected and returned to the unobstructed zone, and 9. skimm ing nozzle located in a position adapted to contact subsided solids within the rotor and effect continuous discharge of such solids therefrom under the influence of the inertia of said solids.

2. A centrifugal separator comprising an imperforate rotor in which subsidence of a mixture of liquid and solids of lower specific gravity than said liquid is adapted to take place under the influence of centrifugal force, and means for feeding a mixture of liquid and solids to the rotor, said rotor comprising a main body portion, means for directing a mixture fed to the rotor into a central unobstructedpart of said main body portion provided with radially extending accelerator members, and a series of closely spaced frustro-conical discs having their .in-

ner circumferential termini radially a substantial distance without said zone of feed, whereby to afford a substantially unobstructed subsidence zone provided with accelerator members within which the major portion of the solids of said mixture is adapted to be stratified from the liquid content of the mixture and a radially outer disc solids therefrom under the influence of the inertia of said solids.

3.- A centrifugal separator comprising an imper-forate rotor in which subsidence of a mixture of liquid and solids of lower specific gravity than said liquid is adapted to take place under the infiuence of centrifugal force, and means for feed- 'inga mixture of liquid and solids to the rotor,

said rotor comprising a main body portion, means for directing a mixture fed to the rotor into a central unobstructed part of said main body portion provided with radially extending accelerator members, and a series of closely spaced frustroconical discs having their inner circumferential termini radially without said zone of feed, whereby to afford a. substantially unobstructed subsidence zone provided with accelerator members within which the major portion of the solids of said mixture adapted to be stratified from the liquid content of the mixture and a radially outer disc zone withinwhich residual solids which flow outwardly with liquid from said unobstructed subsidence zone are adapted to be collected and returned to the unobstructed zone, and a skimming nozzle located in a position adapted to contact subsided solids within the rotor and effect continuous discharge of such solids therefrom under the influence of the inertia of said solids.

4. A centrifugal separator comprising an imperforate rotor in which subsidence of a mixture of liquid and solids of lower specific gravity than said liquid is adapted to take place under the influence of centrifugal force, and means for feeding a mixture of liquid and solids to the rotor, said rotor comprising a main body portion, means for directing a mixture fed to the-rotor into a central unobstructed part of said main body portion provided with radially extending accelerator members, and a series of closely spaced frustro-conical' discs having their inner circumferential termini radially without said zone of feed, whereby to afford a substantially unobstructed subsidence zone provided with accelerator members within which the major portion of the solids of said mixture is adapted to be stratified from the liquid content of the mixture and a radially outer disc zone within which residual solids which flow outwardly with liquid from said unobstructed subsidence zone are adapted to be collected and returned to the unobstructed zone, and a stationary dislodging toollocated in a position adapted to contact subsided solids within the rotor and effect continuous discharge of such solids therefrom under the influence of the inertia of said solids.

LEO D. JONES.

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