US2459944A - Centrifugal separator - Google Patents

Description

Jan. 25, 1949. L. D. JONES ETAL GENTRIFUGAL SEPARATOR 2 Sheets-Sheet 1 Filed Oct. 1, 1945 GAS AND SOL/D5 /MPELLR T Zeb .5; Hay/5 07268 429 garzzazy W a, M

Patented Jan. 25, 1949 Leo D. Jones and Pa, assignors Hugh s. Barnaby, Philadelphia, to The Sharples Corporation,

Philadelphia, Pa., a corporation of Delaware Application October 1, 1943, Serial No. 504,562

3 Claims. (Cl. 183-817) The present invention pertains to a system and a machine for separating non-gaseous impurities from a gas. It was conceived in connection with research having for its object theseparation of solid impurities from a gas, and will accordingly be described in connection with that problem. v

h A feature of the invention consists in the fact that it provides a machine and system which improve the efficiency and economy of separation of solids from gases by providinga centrifugal rotor capable of removing solid impurities of even very small size during passage of the gas under treatment through the centrifugal .roto at high capacity. I

Another feature of the invention. consists in the fact that it inuolves use of a centrifugal rotor in which the gas to be purified is brought upto the speed of centrifugation by accelerating vanes,

and then subjected to centrifugation in a zone provided with a plurality of discs having vanes which retain the gas at the speed of rotation of the rotor during passage through the zones of centrifugationbetween the successive discs, the,

impelling force byiwhich the gas .under purification is fed to and through the centrifugal 1 rotor being derived from means forming no part of the centrifugal rotor; e. g., by an exhauster in a conduit receiving the gas from the rotor, or a blower in a conduit through which the gas is fed to the rotor.

By employing vanes for bringing the. gas up to the speed of the rotor, and providing vanes between the discs and in the space through which the gas is discharged from the rotor, we are able to maintain the rotational velocity of the gas substantially constant during the time it is subjected to centrifugal force in the rotor, thereby minimizing turbulence and promoting. the efliciency of separation.

Another feature of the invention consists in thefact that the internal space into which the Figure 1 is a diagrammatic illustration of a system embodying the centrifugal separator of the invention,

Figure 2 is a longitudinal cross section through a centrifugal separator embodying the features of the invention,

Figure 3 is a cross section on the line3-3 of Figure 2, and V Figure 4 is a cross section on the line 4-4 of Figure 2.

Referring to the drawing by reference characters, Figure 1 illustrates the general principle of operation of the invention. As there illustrate-d, the gas to be purified is sucked, together with solid impurities, from a source through centrifugal separator to by any suitable impelling force, such as provided by the impeller I l. Solids are separated from the gas in centrifugal separator Hi and separately discharged, whilepurified gas is discharged by the impeller. The impeller ll may be a suitable pump, or it may be any other mechanism capable of applying suction' to suck a mixture of gas and solids into the centrifugal separator I 0 and to. suck the purified gas from that centrifugal separator; e. g., it may be an internal combustion engine, and the centrifugal separator Ill may be designed to effect separation of solids, such as dirt, from air Sucked through the centrifugal'rotor to the internal combustion engine for use therein.

a Alternatively, a blower may be'provied to'blow the mixture of gas andsolids through the centrifugal separator It]. An important aspect of the invention consists in the fact that it involves use of a centrifugal separator which has substantially no pumping effect of its own, the impelling force-for feed of gas through the centrifugalseparator to be purified being derived eritirely from a controllable'external impeller.

The centrifugal separator of the invention ;is

illustrated in Figures 2, 3 and 4 ofthe drawing.

gas is discharged after beingsubjecte'd to centrifugation between the successive discs is lOf variable cross section, this cross section increasing in the direction of discharge of the gas from the rotor. By providing a progressively increasing gas space Within the circumferences of the respective discs as the gas flows toward the discharge end of the rotor, more space is provided to receive the gas inwardly fromthe respective discs progressively as the amount of gas to be accommodated increases, with the .result that uniform division of the parallel streams of gas among the spaces between the respective discs is promoted. v

Still further features and advantages of the invention will be evident from a reading of the following specification in the light of the at- In describing this centrifugal separator, we shall assume-for the purposeof convenience of description that it is mounted on a vertical axis as illustrated in Figure 2 of the drawing. In considering this machine, however; it should be realized that it may be mounted on a horizontal axis or an axis located in any plane, 'orthat the position of parts may be upside down with re- ,spectto that illustrated in Figure'2. The'centrifugal separator comprises an external casing 12 in which is mounted a rotor I3' driven by a shaft M from a motor 35. The casing I2 is provided with an inlet l5 at theupper end of its upper frusto-conical section l-B for receiving the gas to be purified, this inlet l5 being connected in a gas-tight fashion to any suitable conduit connected with a source of the gas. "The upper frusto-conic'al section l6 of the casingiscom nected by bolts I! to the central section I 8, which 1 centrifugal-rotor, as illustrated V ofthe drawing. g

23;; supporting the motor 35, by bolts 20.

A plurality of "stationary vanes it (see Figure 3) are provided in the inlet section of the casing, and these vanes are curved as indicated at 36 (see Figure 3) to impart an initial movement of rotation to the gas as enters the centrifugal rotor. The upper end'of the centrifugal :rotor consistsof a feed section 22 comprising a lower frusto-conical wall 23 and an upper frusto-conical wall 2d interconnected lay-vanes 25. 'These vanes 25 are curved forwardly in the'direction of rotation of the rotors-t their upperends, as indicated at 31 in Figure 3, in order to accelerate the gas more smoothly to the speedof the rotor, 1

The feed section 22 of the rotor serves to bring the gas up to the speed, ofthe rotorand to deliver it into the annular portion, of the rotor lying. within the circumferential wallfiii thereof,

and the gas flows from this space into the space 7 between successive discs 28 of a rotating disc "nest 21. The discs 28 are of frusto-conical shape,

and a plurality of vanes 29, "which preferably ex tend substantiall radially between successive discs, serve to maintain the rotation of the gas under treatment at substantially the speed of rotation of the rotor during passage thereof inwardly through the space between successive discs.

An axially extending frusto-conical spacer 30 surrounds the shaft 54 at the longitudinal por tion of said shaft within the inner circumferences of the discs, and this spacer is provided with a plurality of radially and axially extending webs 3| which serve as vanes to maintain the as discharged inwardly from the space between the discs 28 at the rate of rotation of the rotor, and the outer edges 32 of the webs 3i enter notches in the inner portions of the respective discs, and

, thus elfect securement and location or the discs for rotation with the rotor.

It willbe seen-that the cross section of the as progressively more" pockets 43 provided With outlets 44 through which the solid impurities and associated gas are con tinuously discharged from the rotor. At the time these solid impurities and gas are discharged from the outlets 44, they have a high tangential velocity, and this tangential velocity carries them circumferentially around the inner wall of the central section l8 of the casing i 2 until they reach I a vertical longitudinal slot 45 (Figure 4) in that wall, whichextends longitudinally of the wall along the entire length thereof surrounding the discharge outlets M, the solids and gas being discharged through the slot 45 into a discharge conduit 46, which is tapered from the height and Width of slot d5 to a circular section, as illustrated inlligures 2 and '4; A plurality of slots 45 and discharge conduits 46 may be provided around the circumferential wall I8 if desired, although satisfactory operation has been attained by use of only a single such discharge zone, I

It will be seen that the wall substantially isolates the space within the rotor surrounding the discs 28 from the-atmosphere surrounding rotor Within the central section it? of the casing,

the only communication between these two spaces being through the small discharge outlets M, By

I reason of thissubstantial isolation .of the space By reason of this arbetween-respective pairs of discs. By provision of .this larger space, excessive resistanceto'fiow of gases through spaces between the loweridiscs of vthel-disojnest is avoided, and uniform'division of the parallel streams of gas discsof the discnest is promoted.

Upon being discharged from the lower end of the rotor through "the space between the outer circumference- 20 of the'spacer '30 and the inner circumference 3920f the' lower wall of therotor, this gas flows into an annular passageway 4! through which it passes spirally into an outlet conduit 42-,--which may communicate with any suitable" impeller for drawing gas through the V at H in Figure l Solid "impurities with some gas are separated rfrom the gas' during passage thereofthrough the parallel paths-between successive discs 28 and projected outwardly'along thelower faces of these r espective discs under-the'influence of centrifugal force against-a circumferential wall 26, which is provided with a number of indentations forming between respective within the rotor surrounding the discs, turbulence in this zone is minimized, and efficient separation is promoted. If, instead of providing a circumferential Wall 26 havin perforations of small size, the circumferential wall 26 were to be omitted, and the solids discharged directly through the slot 45 and outlet conduit 46 from. the rotating discs, great turbulence would be caused within the space surrounding the discs, withthe result that the separation and discharge of the solid impurities would be a very inefficient operation. This difficulty is avoided in the construction of the present invention by providing a circumferential wall rotating with the discs and having outlets of small size, and efiecting continuous dis-- charge of the solidsfrorn the casingunder the slot on the lowerend 9 ofthe rotor shaft ML bottom section IQ of therotor casing 52 is extended conically' upwardly and inwardly at its lower endas indicated. at 56 and the retainer 5? for the lower bearing 52of the shaft 24 se- The lower bearing 52 also serves to provide indirect bearing support as the top bearing for the shaft of the motor 35.

, The upperend 53 of the shaft 54 is mounted for rotation withina bearing 54 which may be secured to the shaft by. a nut 55, and which is mountedwithin the annular cylindrical central portion 56 of a stationary centralretaining memher 5? which is closed at its central part and provides an upper surface extending in line with the upper surface of the inner frusto-conical wall 23 of the feedsection 22. The central retaining I member 5l, issecured t0, or formedintegrally nected with this member I6 through the vanes or cent the clearance 63, gas

webs H which serve to assist in bringing the gas up to speed as it is introduced into the centrifugal rotor. The feed section 22 of the rotor is secured to'the frusto-conical spacer by bolts 58, and the shaft I4 is keyed to the spacer30 as indicated at 59. The lower end of the spacer 30 is provided with a flange 60 extending outwardly from a web formed at the under end of the spacer. and this flange 6D constitutes theinner portion of the bottom 33 of the rotor, being secured to an intermediate section 6| which is in turn secured to the circumferential wall 26 of the rotor.

It will be seen that the shaft l4 drives the cone 30 through the keyed connection 59 and that this results in driving all of the rotor parts, including the discs 28, at the speed of the shaft. It will also be seen that, when the bolts 58 are secured in position against the upper side of the inner frusto-conical wall 23 of the feed section 22, this securement, acting through the respective vanes 29 and'discs 21, serves to clamp the entire disc assembly tightly in the position illus- -'trated in the drawing.

F'rom'the above discussion, it will be seen that the rotor and all associated parts may be removed from the casing by merely removing the upper, frusto-conical section l6 and nut 55 and lifting the rotor from the shaft l4. upwardly from the casing and from shaft M. The motor 35 is secured to the bottom section is of the casing 12 by bolts 62, and this motor may be removed from its association with the centrifugal separator by removal of these bolts 62.

The disc nest and feed section of the rotor may be separately removed from the rotor for cleaning or any other purpose, after removal of the section l6 of the casing l2 and nut 55, merely by removal of the bolts 58, and lifting of the feed section and then the discs from their association with the remaining rotor parts.

It will be seen from the above discussion that the machine of the invention provides bearing and driving connections by which the rotor may be driven at high speed with a minimum of vi-. bration. The relatively rigid mounting of the rotor driving andbearing connections enables us to provide relatively moving parts with very small clearances; and thus minimizes the dangers and disadvantages which would be caused by substantial leakage. Thus, the clearances 63, 64, 65, 66,

etc. between rotor parts and stationary casing parts may be very small with'the' driving and bearing connections described above.

the space surrounding charged gas is avoided.

were to leak into the purified gas as it is dis charged from the space 38 into the stationary discharge passageway 4|, this would, of course, offset to a large extent the advantages attained in the previous purification of this discharged gas. A close-clearance labyrinth seal is provided between the innermost portion 66 of the bottom of the rotor and an upwardly projecting portion 6'! of the bottom section IQ of the casing, as indicated at 6B. In view of the importance of avoiding flow of air containing impurities inwardly through this space from the space surrounding the rotor, however, we also provide impelling blades 69 and iii designed to create an outward flow of air through the space adjacent the bottom of the rotor. Thus, in order to obviate all possibility of inward flow of air and/or dirt'through this zone, we provide impellers which cause flow of air outwardly.

The provision of the vanes 25 in the feed zone and the absence of such vanes in the space between the inner circumference of the frustoconical section 16 of the casing and the outer An important factor in preventionof undesirable leakage also results from the provision of special sealing arrangements and impellers. Thus, by providing the inter-connecting vanes 25 in the feed section 22 of therotor extending upwardly to a portion of the feed section adjais subjected. to a very positive impelling effect in this zone which causes flow thereof through the feed seetion, 22 into the main body of the rotor. Insofar. as there is any flow whatever of gases through the clearance 63, this flow is a flow outwardly throughfthe clearance 63 intothe feed;,-zone, rather than the reverse. As a result of this provision of means for positively impelling gases outwardly through the clearance 63 toward the main body of the rotor the difficulty which would be encountered if the impure gases were to leak into the bearing space is avoided.

Even more important than the features discussed above for avoidance of leakage" of impure air into the bearing space is the-construction the feed section into the main body of the rotor .at a speed of rotation approximating that of surface of the frusto-conical wall 24 of the feed section causes suction of gas inwardly through the space 64 of the wall 24 and the overlying surface of the section l5 of the casing. This suction reduces the pressure in the space surrounding the wall 26,. and this reduction of pressure around the wall 26 facilitates the sealing efiect of the impellers 69 and H3 and 1aby-- rinth seal 68 in sealing the zone of discharge of gas from the rotor from contamination by gas and solids from the space surrounding the rotor.

When the rotor is driven at the high speeds for which it is designed, the pressure in the space surrounding the wall 26 is lower than that in the air spaces of the pockets 53, with the result that a' mixture of the gas under treatment and of impurities is continuously discharged through the outlets id. This lowered pressure in the space surrounding the wall 26 as compared to the pressure within the rotor is also facilitated by the effect of the impeller vanes 25, asdiscussed above.

It will be evident from the above description that air entering the inlet I5 is first given a slight rotational impulse in the direction of rotor rotation by the curved lower edges of the stationary vanes 2|, and that it is thereafter brought up to rotor speed by the vanes 25 in the feed section of the rotor, and passed from the rotor itself. From this zone, the gas is purified during its flow inwardly through'parallel pathsbetween the discs 23, and is thence discharged from the rotor through the passage 4| in the bottom section 19 of the casing and the, conduit 42. The vanes 25 of the feed section 22 of the rotor act as impeller blades to cause flow of gas into the space surrounding the discs 28, but this impelling effect is counteracted by the reverse impelling effect of the vanes 29 between the respective discs 28. By

reason of this counter-acting effect, and the resistance to flow of the various elements of the centrifugal and casing, there is practically no tendency for gas to flow through the centrifugal unless an impeller of some kind is connected to the inlet or outlet conduits to induce such flow. This provision of a machine which has virtually no impelling effect of its own, when combined in I Wall forming-pockets, said pockets having nora system providing the necessaryimpeller, enables the operator to pass the gas to he purified through he centrifugal rotor at a rate best adapted to secure adequate purification of the gas, since the gas maybe passed through the rotor at a low rate in cases in which it is difficult to purify or in which extremely fine puri fication is desired, or it may hepassed at a high rate in cases in which the gas is relatively easy to purify or only relatively coarse or heavy impurities are to he removed.

ince various other modifications are possible, We do not wish. to be ill of the following claims.

We claim: a 1.:In a centrifugal. separator for-separating non-gaseous impurities ironseparating chamber including a plurality of superimposed spaced trusts-conical discsiorming separating spaces between said discs, individual ed except loy'the scope.

a gas, the'conrlbination comprising, centri ugal rotor having a,

radially extending'vanes interposed between opposing faces of successive discs, each said vane extending from one opposed facet/o the other throughout substantially the entire radial extent of the opposed faces to form channels through which gas may flow radially inwardly within the spaces between successive discs during separation of non-gaseous constituents therefrom, a feed zone through which the gas to be purified is conveyed outwardly into said separating chamber,

said feed Zone having aplurality of impeller elements for imparting rotation to said gas to be purified, a peripheral wall surrounding said discs and spaced radially therefrom, a plurality of outwardly extending indentations in said peripheral wall forming pockets, said pockets having normally open holes for the discharge therefrom of precipitated impurities, and a discharge zone in the central portion of the rotor positioned in- .wardly of the inner circumferences ofsaid discs,

said discharge zone increasing progressively in crosssectional area in the direction of flow of gas from the feed zone through said rotor, said:

discharge Zone containing a plurality of radially extending vanes, and a non-rotating receiving member for receiving said gas directly from said discharge zone. 7 i r r 2. In a centrifugal separator for separating non-gaseous impurities from. a gas, thecombination comprising, a centrifugal rotor having a separating chamber including a plurality of su perimposed spaced frusto-conical discs forming. separating spaces between said discs, individual radially extending vanes interposed between 0pposing faces of successive discs, each said vane extending from one opposed face to the other throughout substantially the entireradial extent of the 'opposedfaces to form channels through i which gasmay flow radially inwardly within the spaces between successive discs during separation of non-gaseous constituents therefrom, a feed zone through which the gas to be purified is con"- veyed outwardly into said separating chamber, said feed zone having a plurality of impeller elements for imparting rotation to said gas to' be purified, a peripheral'wall surrounding said discs and spaced radially therefrom, a plurality of outwardly extending indentations in said peripheral mallyopen holes for the discharge therefrom of precipitated impurities, a, stationary wallsurrounding the peripheral wall of said rotor, said stationary wall having a longitudinally extending slot therethrough communicating with a passage directed tangentially with respect to said rotor for directing impurities discharged from said rotor away from the zone of centrifugation' under the inertiaof discharge of said impurities from the rotor, and a discharge zone in the central portion of ,the rotor positioned inwardly of the V "bination comprising, a centrifugal rotor having a separating. chamber containing a stack of .su perimposed spaced trusts-conical discs: With'separating spaces between said discs, vanes interbetween opposing faces of successive discs,

7 said vanes forming channels throughwhichgas may flow inwardly within thespacesbetween successive discs'during separation'of non-gaseous constituents therefrom, a feed zone for conveying feed gas outwardly of said discs intosaid separating chamber, said feed zone having a plurality of impeller elements for imparting rotation to said gas, aperipheral wall surroundingsaid discs and spaced radially therefrom, a fplurality of small discharge outlets in-said peripheral-wall,

said discharge outlets beingdistributed about said stack of discs for the discharge of separated-nongaseous constituentaa discharge zone in the central portoin of the rotor positioned inwardly of the inner circumferences of said disos,-'said discharge zone increasing progressively in cross sectional area in the direction of flow :of" gas from the feed zone through said rotor, and a plurality of radially and axially extending vanes in said discharge zone. 5 a

, 1. 0.1), JONES, HUGH S..BARN1BY. ,nniiERENcEs CITED The following references are of recordin the file of. this. patent: V g

UNITED STATES PATENTS Number Name 7 Date 774,851 McKee Nov. 15, 1904 881,723 Scheibe Mar. 10, 1908 1,008,896 Fisher NOV. 14, 1911 1,303,207 'Kelly et' a1. '1 May 6, 1919 1,363,699 Ward et al Dec. 28, 1920 2,126,481 Lapp et al, Aug. 9, 1938 2,143,144 Fagerberg Jan. 10, 1939 2,171,843 Brock s Sept. 5, 1939 2,173,579 Fawcett se t. 19, 1939 2,406,441 Schneible A ug. 27, 1946 FOREIGN PATENTS v I m Number Country. Date 475,884 Great Britain Nov. 29, 1937 481,257

Great Britain Mar, 8 1938

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