US2750040A - Centrifugal separation - Google Patents

Description

June 12, 1956 P. P. sTRlcH 2,750,040

CENTRIFUGAL SEPARATION Filed Dec. 22, 1951 2 Sheets-Sheet l .lime 12, 1956 P. P. sTRlcH 2,750,040

CENTRIFUGAL SEPARATION Filed Dec. 22, 1951 2 Sheets-Sheet 2 United States Patent cENrnlFUGAL SEPARATION Philippe P. Strich, Montreal, Quebec, Canada, assigner to The Western States Machine Company, Hamilton, Ohio, a corporation of Utah Application December 22, 1951, Serial' No. 262,993

6 Claims. (Cl. 210-73) This invention relates to continuous centrifugal separation.

Trump U. S. Patent 1,933,644, and Sanchez y Cil U. S. Patent 2,096,594, disclose centrifugal separators, using rapidly rotating conical motors, capable of being used to carry out continuous centrifugal separation processes.

These patents discuss the advantages of such processes and describe their application to drying crystals of sugar, salt and other substances. More particularly, the second patent discusses their application to separating molasses or syrup from massecuite.

The. rst patent provided means for regulating the discharger rate of the centrifugate. But, the means employed is' relatively complex, making. the apparatus complicated and cumbersome to manufacture, transport, and use.

An object of.' this invention isI to provide a method and apparatus providing for continuousv centrifugal separation, by which the discharge of the centn'fugate can becontrolled within ne limits and can be easily adjusted during the rotation of the rotor.

This andl other objects and advantages are accomplished by causing the continuous forward movement of the material. being centrifuged through a drying zone solely by centrifugal action, and controlling the introduction of the material to the drying zone by a regulata-ble control of the discharge of the centrifugate, this discharge being regulated by conining the passage of thel material at the end of the drying zone positively by the action of discharge valves which are positioned by a yieldable control force and by a counteracting component or" the centrifugal force or said material so that theV extent of the discharge opening is easily adjustable during. the. rotation of the rotor.

This can be done conveniently in accordance with the invention by means of an apparatus havingl the following features. This apparatus includes arotor having a peripheral rim. This rim is formed with a plurality of spaced apart outlet ports, and each of these ports is controlled by its own Valve means. Common actuating means located on the rotor is provided for actuating all the valve means. And control means independent of the rotationof rotor and located ot the rotor, is provided for controlling the actuating means.

More specifically, the apparatus preferably has the following features. The rotor includes a conical perforated basket rotatable on a horizontal axis andV having an annular skirt at its periphery.` A retaining cone is coaxially arranged within the backet for rotation` therewith, the cone also having an. annular skirt at its pen'phery' overlapping, the basket-skirt to forni a composite rim. The skirts are fixedly cormected together throughout a major area. The basket and cone form therebetween a main passage for material being centrifuged. Outlet passages between the skirt of the basket and the skirt of the cone are spaced apart about the periphery and extend from the main passagey to and. substantially radially through the rim. And valve means as referred ice to above are provided for controlling the flow of the centrifugate or charge solids through each of the outlet passages.

Preferably, each valve means is housed in a recess formed adjacent its outlet passage. Desirably a valve means includes a flap which is articulated to oscillate within the passage, the flap either opening or closing the outlet passage and being urged towards open posiiton by a lateral component. of the centrifugal force of material in the outlet passage. The ap is disposed angularly and swingable in the passage in such manner that the lateral force component is greatest when the ap is in its closed position and diminishes as the flap moves away from that position. In this arrangement, the actuating means is preferably an inflatable elastic tube` which extends through an annular passage formed between the skirt of thek basket and the skirt of the cone. This tube is connected to a conduit located on the rotor and extends therefrom to a rotatable joint at the axis of the rotor. This rotatable joint is connected to a stationary conduit leading to a source of compressed air supply so that the pressure in the ring or tube can be adjusted so as to urge the flap valves towards the closed position with any desired force, or to allow them to be urged by the lateral component of the centrifugal force of the centrifugate towards the open position to increase the opening ofthe outlet. Ey changing the air pressure in the tube while the loaded machine is rotated at full speed, the Valves can be caused to assume any desired position corresponding to a desired rate of discharge through the outlet passages, since the adjusted air pressure will be couuterbalanced by the lateral pressure of the centrifu gate against the valve flaps only at a denite different position of these flaps. in this way the extent of opening of each of the outlets can be easily adjusted while the apparatus is in operation and its adjustment is substantially uniform for the various outlet passages throughout the periphery of the rotor.

The invention will be understood in more detail by reference to the accompanying drawings in which a preferred embodiment is illustrated by wayv of example, and in which:

Figure l is a side elevation, partly in section, ot a preferred apparatus.

Figure 2 is an enlarged fragmentary4 crosssection taken close to the outlet periphery of the basket.

Figure 3 is a vertical cross section along the line 3-3 of Figure l.

Figure 4 is a front elevation partly in section showing particularly the arrangement of the valves controlling the outlet ports. v

Figure 5 is an enlarged fragmentary vertical cross section along the line 5 5 of Figure 4, showing the valving arrangement.

Figure 6 is an enlarged fragmentary vertical cross section along the line 6-6 of Figure 4.

Referring more particularly to the. drawings, the apparatus. includes a foundation A carrying an electric motor B and pedestals 14 for main bearings C of the entrifugal apparatus. The main bearings C carry a horizontal hollow shaft l5. On one end of the shaft le" is mounted a pulley 17 about which passes a plurality of endless belts 19 driven from a pulley 22 which in turn is mounted on the shaft 23 of the electric motor B.

On the other end of the shaft 15 is mounted the centrifugal rotor D including two centrifugal cones, one an outer basket 25 and the other an inner cone 39. The cones 25 and 30 are separated by a space 28 in which the massecuite will travel. The wall of the basket 25 may be similar to the Walls of an ordinary vertical basket used in separating sugar, but the holes allowing the syrup to be spun off preferably are on the same circle and are preferably situated as close as possible to the places of division or partition between the zones of separation of the lirst and second syrups, between the zones of separation of the second syrup and sugar, and so on. One or two large mesh screens can be used, but the screen in contact with the massecuite musthave perform tions as small as consistent with good operation. Screens 26, 26a and 2.612 of increasing mesh size here line the inner face of the basket 25. These screens space apart the sugar from the inner wall of thc basket and give the syrup a chance to separate from it. This will be understood by those skilled in the art.

The basket 25 has an outwardly-extending annular skirt 50 on which there is an inwardly extending annular llange 49. The flange 49 serves to bear against the ends of the screens 26, 26a and 2611 preventing them from slipping forward. The cone 30 also has an outwardly.- extending annular skirt 43 which overlaps the skirt 50 of the basket and is removably connected thereto by bolts a. To the skirt 50 is xed, also by the bolts 50a, a ring 5i. This ring 51 has a structure shown in the drawings and to be described. The structure formed by the skirt 50 and the ring 51 includes recesses constituting outlets and an annular housing for valve means controlling them.

To explain, the ring Si includes a continuous recess 52 in its forward face, which extends about its entire periphery. Likewise, the skirt 50 includes a continuous recess 5011 in its rear face forming with the recess 52 throughout the major portion of the annular housing a passage E for an inflatable elastic tube 75. The outer faces of the ring 51, skirt 50 and skirt 43 constitute a cylindrical end face of the rim of the rotor.

Spaced apart about the skirt 50 are openings 5S, each y joining the space 2S and extending to an outlet 55a in the end face of the rim of the rotor. Each opening 55 is bordered at the rear thereof, beyond the tube passage E, by a recessed forward face portion 55h of the skirt 50, which is spaced from the adjacent rear face portion of the skirt 43. Forward face portions 55e of skirt 50 separate the openings 55` being arranged to meet and seal against the rear face of the cone-skirt 43. In communication with the tube passage E, each opening 55 has a. relatively deeply recessed portion, as seen at F in Fig. 5, which extends through skirt 50 and into an indentation 51a in ring 51. Each recess F is bordered at its inner end by a wall 55u' in skirt 50. Each recess F provides a housing for a valve arrangement. It is important to note that side walls 55e and 55f of each opening 55, as seen in Fig. 4, converge toward the outlet 55a, so that the openings 55 taper from wide mouths at their inner ends adjacent to the main passage 28 to relatively narrow outlets at their outer ends. So the centrifugate, that is the solid component of the charge material, such as sugar, is concentrating in approximately triangular outlet passages toward a relatively small outlet at the apex of cach passage. The tiap of the valve controlling these outlets in the preferred arrangement is also triangular in shape.

Thus between them the skirt 50, the ring 51 and the skirt 43 enclose the channel E extending about the periphery of thc rotor D and the spaced apart passages 55 which serve as outlets from the centrifnging space 2S and merge with deeper recesses or pockets F which constitute housings for a valve arrangement controlling these outlets.

The inner cone 30 is provided at its smaller end, as seen in Fig. l. with a diagonally-inwardly-extending annular ange 40 forming a feeding cone.

The actuating means for controlling the outlet openings 55 inciudes the following features. For each opening there is a ap valve having a ap 57 which is articulated to the skirt 50 by brackets 57a bolted to theskirt. The ilap 57 is located at a point close to the wall 55d,

and it has side edges near the walls 55e and 55f and a tip overlapping the recessed face 55h of the skirt 50.

Each flap 57 is connected by a screw 65 to a flanged tubular socket 66 having an annular flange 67. A screw 68 is set as at 69 into the ring 51. Each screw 68 carries a spring 70 which acts on the flange 67 between it and the head of the screw tending to draw the tip of the ap 57 towards the surface of wall 55b on which it seats.

The tubular ring of elastic material, preferably of rubber or synthetic rubber, extends about the annular channel E and bears against the rear face of the ap 57 which preferably includes a boss 57C adapted to engage the tube 75.

A conduit 78 held on the basket 25, leads from the ring 75 to a conduit 79 passing through an opening 80 in the ring Si as shown in Fig. 2, and is adapted to supply air to the tube 75. This conduit continues through part 82 and concentrically within the hollow shaft l5 and connects with the special revolving joint S3. A valve S4 connected to the stationary pipe 35 which is connected to the other side of the joint S3 controls the supply of air to the tube 75,

A pipe 90, concentric to the cone, extends from the forward end thereof for introducing charge material to be centrifuged, for example, massecuite. The pipe ends adjacent to the feeding cone 40 of the inner basket 30.

A water pipe 92 extends from a suitable source of water supply to adjacent the inner end of the inner cone 30. The inner cone 30 is provided with an inwardlyextending baffle 31 and openings 32 to oblige the water to enter the space 28 between the two cones.

The entire rotor assembly up to its rim is surrounded by a stationary receptacle 33 which has an annular end wall 34 near the smaller end of the basket 25, another end wall 35 near the rim, and an intermediate partition 36 which divides the receptacle into separate compartments for collecting liquids expelled from the charge material in different zones of the basket. A discharge pipe 96a extends from the bottom of the rst compartment of receptacle 33 to allow one purged liquid, say the green syrup in sugar processing, to be drawn otf; While the farther compartment is provided with a discharge pipe 96b for taking off another liquid such as the wash syrup produced in sugar processing.

A discharge hood 97 envelops the front of the cone to catch the centrifuged solids, for example, sugar, projected from the openings 55, and a pipe 98 leads from the hood 97 to carry off these solids.

The two cones 25 and 30 are not homothetic, that is, the inner surfaces of the cones tend to converge towards the front or wider side of the cone. Also, the outer cone or basket is reinforced as at 25a because centrifugal force tends to break the basket.

Operation An illustrative cycle of operation of the apparatus as used for centrifuging sugar massecuite is as follows:

The machine is started and the cones are rotated at a speed of between 1500 and 2000 R. P. M., preferably around 1800 R. P. M., depending upon the diameter of the rotor and the centrifugal effect desired in its operation.

The massecuite is fed directly from the usual mingler preferably after passing the massecuite through a small press after the mingler. Usually the massecuite is heated to about F. The massecuite passes from the press and arrives at the discharge end of the pipe 90 and enters the feeding cone 40. Centrifugal force causes the massecuite to proceed outward on the cone 40 and whence it enters the space 28 between the cone 30 and the basket 25. The space 28 becomes filled with massecuite and remains lled with massecuite in its various degrees of extraction, the product, of course, being centrifuged sugar at the outlet end. The converging of the surface atentamof the basket 25 and` cone 30 isI designed to' keep a substantiall-y constant speed' of the sugar alongV the screen. Immediately the massecuite .is projected ontothe walls of the basket 25 the green syrup isextracted progressively as it travels outwardly on the surface of the basket 25. The syrup goes out through the holes 25b. When the. extracted sugar approaches the outerend3 of the centrifuge it passes through the discharge outlets controlled by` the valves 57.

The inner surface of the basket 25 is, practically speaking, divided into a purging zone which extends substantially between the inner opening and the second opening 25b, a washing zone4 which extendsy substantially between the second opening and the third opening and a drying zone which extends substantial-ly between the third opening and the final opening. The: rough location of these zones is shownbet-weenthe chain lines. The centrifugate is well dried crystalline sugar.

Air pressure in the elastic pipe 75 is adjusted until good sugar is coming through the outlets. A skilled operator can tell by the appearance of the' sugar when it is of proper quality. For any given' speed of basket rotation and type of charge material, the solids in the outlet passages will have a certa-in centrifugal force which will be exerted against the valve flaps 5T when they lia-ps are fully closed and will produce a different lateral component of force against these flaps for each different angular position of the aps. Since this lateral component of force urges the flaps away from their closed position in opposition to the air pressure in tube 75, and since it diminishes as the extent of opening of the outlet passages increases, the extent of such opening is determined by the magnitude of the air pressure in tube 75 and can be adjusted to give any desired rate of discharge simply by adjusting the air pressure without changing the operating speed of the machine.

Water is introduced continuously through the pipe 92. So, in elfect, the zone between the water inlet 32 and the third circular series of basket openings is the washing zone.

While the preferred form of the actuating means has been shown as pneumatic, it is understood that this could, in the broader aspects of the invention, take other forms. For example, it could be operated mechanically or electrically. But, the pneumatic form is the preferred one.

The parts will, of course, be made of suitable materials as is well understood by one skilled in the art. The tube 7S must, of course, be suitable durable resilient material like rubber, or one of the synthetic rubbers.

While the invention has been described particularly in connection with the separation of sugar from massecuite, it will be understood that it is also applicable to other centrifuging problems of an equivalent nature, particularly where a solid has to be separated from a liquid. It also will be understood that the particular embodiment here shown and described is merely illustrative and that many alterations and substitutions can be made init while still making use of the subject matter herein disclosed and claimed as my invention.

I claim:

1. A centrifugal machine comprising a conical perforated basket adapted to be rotated continuously at a high speed, said basket having an annular skirt at its outer margin, a retaining cone within the basket for rotation coaxially therewith, said cone having an annular skirt at its Outer marging overlapping the skirt of said basket and being fixedly connected thereagainst throughout a major area thereof, said basket and cone forming therebetween a main passage for material being centrifuged, a circular series of separate outlet passages between the skirt of the basket and the skirt of the cone, each of said passages having a relatively wide mouth connected with said main passage and converging to a relatively narrow outlet at the outer periphery of said skirts, said basket skirt having a recess therein at one side of each of said outlet passages,

6 each of. said recesses including a shallow apex portion opening atA the periphery of said' skirt andl a deeper recessed portion terminating in an end wall near the inner endof the outlet passage, a valve flap articulated to the basket skirt in each deeper recess portion adjacent to its saidy end wall, said iiap being seated on said apex portion in an open position and forming a side Wall portion of the outlet passage that is swingable between said openy position and a closed position in which it extends towards said cone skirt at anr increased angle to the path of discharge of material. in. the: outlet passage, the lateral component of the centrifugal force. exerted on said nap. by'such. material being substantially greater when the flap is in said. closed position than when it is in said open position, a tube channel interconnecting said deeper portions of said recesses about the circumference of said basket, an expansible tube in said channel to urge all of said 'aps towards said closedposition, and a uid supply tube connected with said expansible urbe and extending from it` away' from the basket for conducting fluid under pressure into said tube to regulate the positionof said valve naps.

2. A centrifugal machine as' described in claim. l, andi springl means normally urging each of said valve flaps towards said open position.

3L A centrifugal machine as described in claim l, the skirt of said cone forming the forward side wall of each of said outlet passages,

4. A centrifugal machine comprising a conical perforated basket adapted to be rotated continuously at a high speed, said basket having an annular skirt at its outer margin, a retaining cone within the basket for rotation coaxially therewith, said cone having an annular skirt at its outer margin overlapping the skirt of said basket and being xedly connected thereagainst throughout a major area thereof, said basket and cone forming therebetween a main passage for material being centrifuged, a circular series of separate outlet passages between the skirt of the basket and the skirt of the cone, each of said passages having a relatively wide mouth connected with said main passage and converging to a relatively narrow outlet at the outer periphery of said skirts, said basket skirt having a recess therein at one side of each of said recesses including radially spaced inner and outer forwardly facing surfaces spaced from the cone skirt, a deeper recessed portion between said surfaces, and oppositely facing lateral walls meeting the cone skirt to define lateral sides of the outlet passage, a valve iiap articulated in the deeper portion of each recess near said inner surface thereof, said Hap having sides ilush with said lateral sides thereof and a tip adapted to seat on said outer surface thereof in one position and to seat on the cone skirt in another position, a lateral component of centrifugal force urging the valve liap in each outlet passage towards i said one position during the operation of the machine,

actuating means for urging such valve ap towards the cone skirt in opposition to said component of force, and control means extending away from the basket and cone and operable independently of their movement for adjusting the force of said actuating means so as to control the position of such ap valves during such operation.

5. In a continuously rotated centrifugal machine comprising a rotary tapered basket and a coaxial rotary retainer spaced inwardly from the basket, the basket and retainer defining therebetween an annular passageway of progressively increasing diameter for material being centrifuged and forming a discharge rim at the larger end of said passageway, a substantially radial outlet passage in said rim communicating with said annular passageway for discharging centrifuged material, a valve element forming a wall portion of said outlet passage and movable laterally therein to and away from a position in which it substantially closes the path of discharge of material therein, said valve element having a face disposed obliquely across said path when in said position so that a lateral component of the centrifugal force of material in said passage urges said element laterally away from said position while the machine is operated, the magnitude of said force cornponent diminishing as said element is moved laterally away from said position, and yieldable means for urging said element toward said position with a counterbalancing force sulicient to maintain a desired degree of opening of said outlet passage.

6. In a continuously rotated centrifugal machine comprising a rotary basket having a perforated conical side wall and a coaxial rotary retainer secured to the basket and spaced inwardly from said side wall, the basket and retainer defining therebetween an elongated annular passageway of progressively increasing diameter for material being centrifuged and forming a discharge rim at the larger end of said passageway, a plurality of circularly spaced outlet passages extending substantially radially from said annular passageway through said rim for discharging centrifuged material, a separate valve element in each of said passages forming a lateral wall portion thereof and movable laterally therein to and away from a position in which it substantially closes the passage, said valve element in each passage being disposed obliquely across the same when in said position so that a lateral component of the centrifugal force of material in the passage urges the valve element laterally away from said position while the machine is operated, the magnitude of said force component diminishingfas said element is moved laterally away from said position, fluid pressure responsive means operative upon the valve elements of all of said outlet passages for yieldably urging the same toward said position, and'means connected with said uid pressure responsive means and extending away from said basket for regulating the force of said uid pressure responsive means so as to position said valve elements at any desired degree of opening of said outlet passages.

References Cited in the tile of this patent UNITED STATES PATENTS 364,941 Latferty June 14, 1887 459,197 Bodge Sept. 8, 1891 650,832 Gilain June 5, 1900 1,546,871 Thompson July 21, 1925 1,933,644 Trump Nov. 7, 1933 2,096,594 Sanchez y Cil Oct. 19, 1937 2,104,162 Macklind Ian. 4, 1938 2,113,321 Harrington Apr. 5, 1938 2,232,768 Buddeberg Feb. 25, 1941 2,254,455 Sorenson Sept. 2, 1941 2,517,820 Aagaard Aug. 8, 1950

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