US1581089A - Centrifugal basket - Google Patents

Description

April 13,1926. 1,581,089

E. ROBERTS CENTRIFUGAL BASKET Filed June 30; 1923 5 Sheets -Sheet 1 COO J m A. Q Mom MGM wow wow c o 2 M u 1 o o o o v n o o o o o o o o -m m 0M0 own 0M0 owe a o 0 0 0 o \o o o 0/ i I /Z\\ A ril 13,1926; 1,581,089

E. ROB ERTS CENTRIFUGAL BASKET Filed June 50, 1923 1 5 Sheets- Sheet 2 WM MW) K April 13 1926.

E. ROBERTS CENTRIFUGAL BASKET Filed June 50 192-3 5 sheets sheet .5

A r ii1a, 192e.' 1,581,089

E. ROBERTS GENTRIFUGAL BASKET Filed June 30, 1923 5 Sheets-sheet 4 April 13 1926. 1,581,089

E. ROBERTS CENTRIFUGAL BASKET Filed June 30, 1923 5 Sheets- Sheet 5 Patented Apr. 13, 1926.

UNITED STATES PATENT OFFICE.

EUGENE ROBERTS, OF SALT LAKE CITY, UTAH, ASSIGNOR TO THE WESTERN STATES MACHINE COMPANY, OF SALT LAKE CITY, UTAH, A CORPORATION OF UTAH;

CENTRIFUGAL BASKETS Application filed June so, 1923. Serial No. 648,676.

T aZZ whom it may concern:

Be it known that I, EUGENE Ronnn'rs, a citizen of the United States, and resident of Salt Lake City, in the county of Salt Lake and State-of Utah, have invented certain new and useful Improvements in Centrifugal Baskets, of which the following is a specification.

In the manufacture or refining of sugar or like materials by centrifugal separation of the liquid content, whether syrup or wash liquid, from the solid content or grains, much difficulty has been experienced in providing means for effectively retaining in the centrifugal basket the solid grains or crystals while permitting the rapid escape of the liquid content through the basket wall. Heretofore it has been the practice to punchor drill discharge holes of inch or 2 less diameter through the basket wall with centers an inch or more apart. Against the inside face of such perforated basket wall was placed the filter elements comprising a very finely and closely perforated screen of thin sheet brass or the like with a backing of wire mesh. 3 The great outward pressure of .the solid sugar against the screen due to centrifugal force tended to flatten the wire mesh against the inside wall of the basket so that therewas practically little or no drainage of the liquid over the greater portion of the imperforate areas of the basket between the basket wall perforations. As .the perforations occupied only a small perthe process of effecting the desired separation of the-liquid juice from the solid grains of sugar or other material was unduly prolonged, thus wastingtime and thereby recentage of the total area of the'basket wall ducing the output of each machine, while the washing operation was not only unduly to resist the powerful outward the sugar and yet allow the liquids to flowfreely into the drainage passages without screen under the pressure of the sugar to press the wire mesh backing into such holes and thus injureboth lining and screen and cause them to smear with sugar whenever such backing or stretching occurred.

The present invention overcomes these difficulties by providing a filter construction for the basket wall so arranged and dimensioned as to afford practically complete drainage for the entire area of the sugarsustaining basket Wall instead of affording dralnage merely for only a. small portion of said area as hereto-fore, thereby materially aabbreviating both the duration of the juiceseparating operation and that of the washing operation besides decreasing materially the quantity of water required and the consequent waste of sugar carried ofi' normally closed .aga-inst'percolation of the liquid by reason of the fact that the attach.-

ing ring, the sub-tending part of the basket and the outer reenforeing band form a solid annular'wall preventing any effective drainage so that the opposed section of the sugar wall 'is very imperfectly treated both as to extraction of the juice and as to washing of the sugar grains. 4

According to the present invention -1 overcome this difiiculty'by \providing this attaching rim or flange of the basket bottom this type of machine, with adequate drainage passages which are covered by a sieve-like screen or stralner so sup 'rted as rust of material obstruction. j s

For the first time in the history of-the art this invention provides a filter construction for a centrifugal basket in which the entire sugar-sustaining area of the-basket wall is the basket wa l itself.

effectively drained without'leaving considerable areas practically devoid of drainage facilities. x Y

These and other features of the mve tion will be particularly described in the following specification and will be defined in the claims hereto annexed.

In the accompanying drawin illustrated some of the forms W trate the principles and vention, in which:

Figure 1 is an elevation of a centrifugal basket as ordinarily suspended for'use, the wall being partly broken away to show the interior deflector.

Fi re 2 is a plan view of the same, part of the top of the basket being broken away.- Figure 3 is a centrifugal. section through one side of the basket illustrating the arrangement and construction of filter elements. 7 i J Figure 4 is a similar section showing the the wall-sppporting rim s I have ich illus basket adjacent to of the basket bottom on a larger scae.

Figure 5 is an isometric elevation of a portion of the basket wall as viewed from the interior illustrating the progressive building up of the different layers or elementsof the filtering wall.

Figure 6 is a sideelevation partly in section of the assemblage shown in Figure 5. Figure 7 is a similar view showing a part of the grid, or ocket-ferming element of the filtering wall Figure 8 is a face view as seen from the inside of the bridge plate which forms a support for the filtering elements over'the shallow pockets.

Figures 9 and 10, show, respectivel in elevationand in crosssection a mo ified the basket wall in which form of a portion of grid is integral with the filter-sup orting Figures 11, 12 and 13 are sectional views through the basket wall' adjacent to the overlapped joint of the bottom and side wall illustrating modified constructions for draining this area.

tom ty cable toprotecting conical bottom and Figure 14 is a horizontal section through a short length of'the basket wall adjacentto one of the joints betweensthe sections.

Since a similarly constructed filter wall for covering the perforations in the peri'ph-' eral or cylindrical wall of'the basket may be equally 'well used for the fiat valved bottom se f-discharging basket, in the accofnhave'illustrated the cons latter type of-ba'sket because of certain additional features that are peculiarly applithe" joint between the the cylindrical wall of a self-discharging basket. j

The perforated. basket, therefore, embraca central spider 8 practice of this in tion 12 may be properly drained placing against by means of a somewhat e of basket and for the ta'gered bot-,-

ing the cylindrical wall 1, the sloping top ring 7, and the conical base orlbottom 9, formed with an upper attaching ring or flange 9 and a lower attaching flange 9", is suspended in the usual manner by means of whose peripheral band 8" fits inside the lower flanged end of the conical bottom on the rotary basket shaft 2, which is coupled to the upper rotary shaft section 5, carried by thegyratory suspender 3 on a ball and socket joint at 4, by means-of hung a flanged connection shown at 6, according to present well known practice, in order that the basket may rotate and gyratein use.

' Both the cylidrical wall 1, and the hot I tom wall 9 are provided with liquid discharge openin s 12 whose inner edges are preferably slightly flared or countersunk as shown at 15 in order to more readily collect the liquid that percolates through the filtering material into the shallow collecting pockets, hereinafter mentioned, surrounding each discharge perforation. I

In order that the imperforate parts of the basket surrounding each dischar e perforathe basket walls with shallow drainage pockets on its interior face, 'referably by said interior ace a grid 20 I provide consisting usually of sheet metal with the major part of the sheet cut out to form windows or openings arranged to surroundeach perforation 12 but of considerably larger area than such erforations, these pockets being bounded y relatively narrow ribs forming the grid as best shown in Figure 5.

, Such grid is placed inside the basket and is preferably riveted br otherwise secured thereto at suitable. intervals, the abutting ends bein brought together but not overlapping, his construction, therefore, rovides a .series of shallow drainage poc etc on the interior face-of the basket wall of much larger area than it would be practicable to make the perforations themselves and of much larger area, than the solid ribs or arts of the grid that bound the pockets.

he preferred construction for the filtering elements comprlses a finely and closely perforated sheet metal screen or sieve 23 backed by a somewhat coarser wire mesh fabric 22 which itself is "supported against buckling into the shallow plockets or recesses eavier and more coarsely perforated bridge plate 21, as shown in enlarged view in Figure 4. These three-elements may conveniently be riveted together and preferably, instead of making them in one continuous ring to fit inside the basket wall, they are made in any desired number of sections div'ided vertically with the screen or sieve portion 23 continued slightly beyond the abutting joint of the sections to overlap and protect the vertical Usually the basket rotates in a clockwise direction, and in such case the overlap of the screen cross joint would be thatindicated'in Figure 14, the rear edge of each section overlapping the forward edge of each following section considered with regard to the directlon of rotation of the basket.

/With the sectional arrangement described it will usually be found advantageous to rivet the coarsely perforated brid e or supporting plate 21 and the two filtering layers 22, 23, together as illustrated at 25 in Figure 4. Any suitable means may be employed for retaining the interior composite filtering wall in position, butin the present instance I have shown such filtering wall held in place by the outer adjacent edge of the top filtering element 26 and of the lower filtering element which slightly overlap the top and bottom eaves respectively of the composite filtering element, as illustrated in Figure 3, but in this case without tightly binding against the filtering element since a slight creep of the latter relative to the basket wall is not necessarily injurious.

The ring of sugar building up against the underside of the top ring or rim 7 of the basket should be completely drained to obtain the most effective results and, therefore, I provide an annular composite filtering element comprising the coarsely perforated plate 26 similar to plate 21 which is covered on the side toward the sugar wall with acorresponding plate or strip 27 of finely perforated screen, similar to the screen '23, which is preferably riveted to the supporting plate26. In order' to space this top filtering wall from the solid face of the rin I provide a series of narrow radial ribs 7 on the undersideof the ring 7 so as tofo rm shallow radial passages for the flow of the extracted liquid outwardly to the adjacent discharge openings 12.

To'effectfull and complete drainage of the filtering wall covering the frustno-conical bottom of the basket I provide the inner ,face of the inclined bottom wall 9 with a series ofshallow. supporting ribs 13, which, in this instance althoughnot necessarily, ex tend around the inside ofthe bottom at properly spaced intervals in a circumferential direction in order to form shallow drainage pockets 14. The uppermost of these drainage pockets as most clearly shown Figure 4, extends well toward the top of H the connecting-ring or flange 10 and at its upper edge communicates at intervals through drainage passages 10 with the perforations 12. formed in the outer wall of the basket. All-these drainage passages in the bottom are covered by means of a relatively heavybridge plate or screen-supporting element 30 on the inside of which is mounted a finely perforated screen orsieve g 12 in the basket wall 1.

31, similar to screen 23. As shown in Figures 3 and 4, the upper edge of the filtering screen 31 projects slightly beyond the edge,

form a slight overlap. Attaching screws 33 .ofits supporting plate, as shown at 32 to} or equivalent means are passed at intervals through the screen wall 30, 31, into the ribs 13 to hold the filtering wall in place, and as an additional means of resisting the upward thrust due to centrifugal force annular ribs 34 are fastened to the outer face of the plate 30 in position to engage the lower side of the spacing ribs 13 and thusrelieve the pressure on the attaching screws.-

From the foregoing description and an inspection of the detailed construction and arrangement illustrated in Figure 3 it will be seen that there is no part of the finely perforated filtering screen that is not in communication with outlet or drainagepassages and that, consequently every smallest portion of the wall of sugar or other solid is subjected to the most'complete drainage ac tion since there is no solid wall preventing the flow of liquid to the basket wall discharge outlets under the action of centrifugal force. \Vith all parts of the sugar wall fully drained very rapid and effective separation of the liquid syrup or wash water is accomplished without producing substantial areas of-imperfectly washed material.

In Figures 9 and 10 I have shown a slightly modified form inwhich the pocketforming grid 20 corresponding to the pocket-forming grid 20, above described, is formed integrally with the basket wall by countersinking shallow pockets 20 which communicate with the discharge openings As will be seen these circular pockets 20 cover much the greater portion of the inside face of the basket wall and function precisely as do the pockets formed by the separate grid 20.

In Figure 11 I have shown in vertical cross section a modified form of construction in which a. separate detachable ring 35 is inserted above the attaching ring 10 to form a supporting ledge upon which the bottom edge of the composite filtering wall rests, and also a downwardly turned ledge 35 to support the upward thrust of the filtering wall 30, 31, which latter is similar to that already described for theconical bottom 9. In this case tbs; inclined inner face of the screen-supporting ring 35 is protected by means of an annulan bridge plate 36 made in circumferential sections and covered with the finely perforated screen 37. This protecting screen is held in spaced relationship to the inside wall of the ring 35 by means of attaching screws 38 and. vhas its upper and lower edges bevelled to overlap and bear element. The liquid discharges into the 37, similar to that above described rests upon narrow annular ribs 35 and 35 instead ofgetting its outward bearing against the cylindrical filtering element and the conical filtering element, as in the form shown in Figure 11.

In the form shown in Figure 13, the retaining ring 40, is provided with an upper screen-retaining flange 41 and a lower screenretaining flange 42, and is provided with vertical ribs 43 to support the filtering-plate 36 at frequent intervals. It will, therefore, be seen that where such a screen-supporting ring is used in the centrifugal basket provision may be made in various ways, inaccordance with the principle of this invention, to prevent smearing of the .sugar against the ring by providing ample drainage passages for the inside surface of the ring in communication with the sieve-like perforations of the screen and with the outlet ierforations of the basket wall.

The perforations in the filter-supporting or bridge plates are inadelarge enough to cover a number ofinterstitial spaces in the wire mesh layer and are arranged as closely as practicable without makin the bridge plate too weak to prevent bulging of the filtering element into the'large shallow drainage recesses which they eover. The wire:

mesh is coarse enough to enable each interstitial space to subtend several of the fine perforations in the screen while the round wires and undulating surface of the wire mesh allow suflicient lateral circulation for the very short distance involved to give perfect drainage between the screen perforating and the discharge holes in the basket. The punching out of the grid and of the bridge plate tends to somewhat indent or round the edges surrounding the openings so that there is nowhere presented throughout the whole sugar subtended wall any substantial impediment to the rapid escape of liquid through the basket wall. Thus full drainage is provided for every portion. of the walled up material, and all the screen perforations are in communication with the discharge holes in the basket wall.

This will be clear if we consider that the solid strips forming the spacing grid need of the liquid to the discharge holeso basket wall. Furthermore,.as the interstices the conical bottom screen and between said screen and said vided with closely arran 'ed re atively coarse perforations affording. ree communication not ekizeed th inch in width, and as the perforations in the bridge plate-maybe of 5th inch diameter even the solid parts of the grid form no obstacle to the circulppion 'the of the wire mesh may be as wide or widen than the width of the solid portions of the bridge plate, and as the wires of the mesh, even when directly opposed to a row of fine perforations of the screen, still leave room for the escape of liquid through the fine perforations the percolation of the liquid, under centrifugal force, from every perforation in the strainer screen is permitted. Hence it is that complete drainage is afiorded to every part of the walled-u material with resulting absence of any dar 'zones or areas of syrup-bearing or unwashed sugar and this, too, with the use of a less volume of wash water and with a material shortening of the cycle o-f'centrifugal operations.

Intermediate of the top and bottom annular walls ofthe'basket I provide a circular deflector plate 50 secured to the basket shaft 2, and having on its upper face radiating ribs or flanges 51, which are bent back relative to the direction of rotation of the basket in order to' retard the centrifugal action from throwing off the fed-in material to the wall of the basket while accelerating the rotary motion of the material before it impinges against the surrounding basket wall.

What I claim is:

1. A filterin construction for a centrifugal basket em racing in combination with a surrounding basket wall formed ,with discharge perforations well spaced apart, an interiorly disposed fine foraminous filter screen, an intermediately dis osed relatively stiff bridge plate having 0 osely arranged coarse perforations while providing "substan tially level support at intervals to sustain the screen against Ioutward bulging under pressure, and spacing means afi'ording at intervals exterior supportin engagement with the bridge plate to form-drainage spaces on the interior of the basket wall directly tributarl to discharge perforations in the basket wa 2. A filterin construction for a centrifu-' gal basket em racing in combination with the surrounding perforated basket wall, a

grid member whose openings occupy the drainage pockets directly tributary to the ion liquid discharge perforations of the basket wall, a fine foraminous filter screen support ed against bulging into said ockets under the outward thrust of the has et load by a relatively stiff bridge plate being interposed id and probetween the filter perforations and said drainage pockets whereby the rapid escape of the centrifugally extracted liquid is facilitated, substantially as described.

S. A filtering construction for a centrifugal basket embracing in combination with filterserecn, and a supporting grid interposed between the basket wall and the bridge-plate to separate the bridge-plate from contact with the basket well, said grid having openings of substantially larger area than the area of the basket Wall perforations forming drainage pockets around the basket wall perforations, substantially as described.

' 4. A filtering construction fora centrifugal basket embracing in combination with a perforated basket wall, a spacing element arranged against the inside of the basket and provided with openlngs of substantially larger area than the basket wall perforations thereby forming shallow drainage pockets around the basket wall perforations, a fine foraminous filter screen arranged interiorly of the spacing element to allow the escape of centrifugally extracted liqmd while retaining the solid contents of the basket, and means interposed between the spacing element and the-filter screen to support the filter screen against bulging into said pockets while allowingthe extracted liquid to flow freely thereto, substantially as dey scribed.

face of the basket to leave shallow drain-- age pockets of larger area than the area of the perforations in the basket wall, a relatively late arranged to bridge over said pockets, a finely perforated sheet metal filter screen, arranged inside said bridge plate and a reticulated backing, interposed T between the bridge plate and the screen, substantially as described. I

6. A filter construction "for a centrifugal basket, embracing in combination with a perforated thrust-sustaining basket wall, a thin finely perforated metallic filter screen, a relatively stiff bridge plate having relatively coarse closely arranged perforations for the escape 'of' the liquid extracted through said screen, said bridge plate affording firm support for the screen to pre vent the screen from bulging out under internal pressure, and spacing means arranged thereby affording free drainage outlets for stiff closely-perforated bridge to separate the bridge-plate from the subtending portions of the basketwall and form drainage pockets communicating with liquid discharge openings in the basket wall,

all parts ofthe screen, substantially as described.

7. A filter construction for a centrifugal basket embracing in con'ibination with the perforated basket wall, spacing-means on its inner face arranged'to form shallow drainag pockets of larger area than that of the bar; et wall perforations, segmental filtering elements each comprising a relatively stiff coarsely perforated bridge plate of segmental form, and a thin, sheet metal finely perforated screen of similar form firmly so cured to said segmental bridge plate, sub stantially as described. v

' 8. A filtering element for acentrifugal basket embracing a relatively stiff coarselyperforated bridge plate of segmental form and a finely perforated thin sheet metal filter screen of like form riveted thereto with one side edge extending slightly beyond the corresponding side edge of the bridge plate to overlap the edge of the next adjacent element when assembled in the basket, substantially as described.

9. A bottom for a centrifugal basket embracing a funnel shaped perforated mem her having upper and lower attaching flanges for connection respectively witha peripheral basket andwith an interior supporting spider, interiorly projecting ledges forming drainage passages leading to liquid discharge openings, a rigid'closely-perforated frustro-conical bridge member inf teriorly supported upon said ledges, and a, frustro-conical filter screen of finely perforated thin metal supported on said bridge plate against outward bulging under pressure, substantially as describe i 10, A. filtering construction for a selfdischarging centrifugal basket embracing in combination with a perforated peripheral side wall, a downwardly converging perforated conical bottom whose upper edge por tion forms an attaching ring in overlapped relation. to the loweredge portion of said side wall, filtering elements arranged to cover respectively the perforations of the side wall and of the bottom, the bottom filterelement embracing a finely perforated filter screen extending-over the inside of the overlapped attaching ring with its perforations subtending said ring draining .into liquid discharge openingsin the'basket, substantially as described.

11. A filtering construction fora self discharging centrifugal basket embracing in combination a perforated side wall, a downwardly converging conical bottom secured to the lower ed e of the sidewall by-an overlapped attac ing rim portioma filterlac ing element e'mbra'cing a thin finely perforated filter screen'formmg an inside cover for shallow drainage pockets surrounding the perforations in the side wall of the basket, and means for supporting said screen against bulging into said pockets while allowing extracted liquid to pass thereto, a

similar filtering element arranged inside the conical bottom to cover drainage areas leading to liquid discharge perforations, the latter'fi'ltering element extending upward to cover liquid discharge passages in the over- .lapped rim portion of the bottom, substantially as described. 1

p 12. A self-discharging centrifugal basket embracing a perforated side Wall and a downwardly converging perforated conical bottom secured together with their adjaage to the perforations therein the filtering screen of the bottom being extended up to overlap the lower edge of the filtering element of the side wall, there being pro vided liquid discharge passages to drain the screen perforations subtending the overlapped" portions of the side wall and the bottom. i

13. A filtering element for the. conical bottom of a self-discharging centifugal basket embracing a segmental frustro-conical screen of thin finely perforated material, a, bridge member of similar shape to which the screen is secured, and means carried by the bridge plate to engage ledges in the bottomof the basket 'to prevent upward shifting of the filtering element under the stress of centrifugal force, substantially as described.

In witness whereofiIhav'e subscribed the above specification.

a EUGENE ROBERTS.

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