US1902982A - Centrifugal filtering device - Google Patents

Description

March 28, 1933. H. w. ABBOTT CENTRIFUGAL FILTERING DEVICE Filed July 24, 1930 2 Sheets-Sheet 1 2 Sheets-Sheet 2 fizz/922?) 1%? @5505? I lllll/ll/l/l 1 aw v Patented Mar. 28, 1933 UNITED STATES HARRY W. ABBOTT, OF CHICAGO, ILLINOIS CENTRIFUGAL FILTERING DEVICE Application filed July 24,

My invention relatesto a centrifugal filtering device for separating liquids from solid matter.

Such devices have a variety of uses and are applied extensively in drying the residue of activated sludge, separating liquid treating solutions from solids in mineral mining processes, etc.

I will describe the device of my invention in connection with the separation of crystallized sugar from molasses in the sugar refining process. When the sap has been extracted from beets, sugar cane or other sugar bearing plants, it is first boiled until the sugar content is in the crystallized stage and the remainder of the sap is in the form of molasses. The sugar is then separated from the molasses by centrifugal means.

An object of my invention is to providea new and improved centrifugal separator or A further object istoprovide a continuous centrifugal filterer.

A further object is to provide an eflicient and effective centrifugal filterer which is simple in construction and economical in operation.

Other objects and advantages will appear as the description proceeds.

Referring to the drawings:

Fig. 1 is a side elevation partly in section of a device embodying my invention,

Fig. 2 is a fragmentary sectional view taken on line 22 of Fig. 3, and

Fig; 3 is a sectional plan view taken on line 33 of Fig. 2.

In general, my invent-ion consists of the use of what I term an air scraper, with a centrifugal separator or dryer which may be of substantially standard type in other respects. The porous element carried by the rotatable head of most centrifugal dryers is a felt or similarmaterial. When such a material is scraped for the purpose of removing the dried residue, there is considerable wear causing frequent renewals of the felt.

Moreover, the manner in which centrifugal separators are now run requires periodical stopping to remove this material, thereby 1930. Serial No. 470,287.

greatly increasing the length of time required to treat a given body of material. I .have alsofound that some materials, such as sewage sludge forexample, is not dried sufficiently on the ordinary type of centrifugal separator. Consequently, I not only employ an air scraper for removing solid material from the porous element, but I do this during the continuous operation of the device by progressively moving therresidue from the top of the head downwardly until it is discharged ofi' the bottom into asuitable receptacle. As the residue is moved downwardly it is turned over periodically, thus freeing particles of waterwhich may be trapped in various'parts of the solid matter and exposing fresh areas so that a drier final product is obtained. The air delivered under pressure also appears to aid in driving moisture through, which otherwise would not be moved by the centrifugal force alone. When the separator is used in thedrying of sugar in refinement processes I also provide means for introducing water for Washing the molasses from the sugar. This is also accomplished progressively so that the final solid product is freer from contaminating substances and drier than with any other type of separator or dryer with which I am familiar.

Now with reference tothedrawings in which the construction of one embodiment of I my mvention is disclosed, the apparatus is mounted upon a base 11 having a pair of upwardly extending standards 12 connected by a cross piece 13. A second pair of standards 14 is mounted uponthecross piece 13 and are connected by a cross piece 15. Each of the cross pieces 13 and 15 supports a journal 16 and 17 respectively. Rotatably supported in journals 16 and 17 is a hollow shaft 18. Journal 16 carries a-ball race 19 cooperating with a ball race 21 upon the hollow shaft to 25 is mounted upon the hollow shaft. These ball races support ball bearings 26, forming a combination radial and thrust bearing. This bearing is also preferably enclosed by being covered with a dust cap 27.

Hollow shaft 18 may be rotated by means of a pulley 20 secured thereon and supports a rotatable head 28 which comprises a top plate 29 which is curved downwardly at its outer periphery and has a plurality of radial vanes 81. These vanes extend longitudinally in an axial direction and carry a lower rim 32 which interconnects the lower ends of the vanes. The lower face of rim 82' is provided r with a circular groove 33 and surrounding therotatable head is a casing g l'having an 7 annular trough 35, one side of which extends means of a plurality of arcuate vanes 38 which extend from a point near the center of the disc to a point close to the periphery of the disc. K i

The material to be dried is fed into the rotatable head through a stationary conduit 39 which extends through the hollow shaft and top plate 29. In order to prevent the lower, end of conduit 39 from vibrating due to rotation of the head, the pipe may be provided with a ball race ll which cooperates with a ball race 42 to retain ball rollers l3 therein and form a ball bearing support for the lower end of the conduit. Material 'fed into the conduit 39 is passed into the upper portion ofthe rotating head and deposited upon disc 37. The rotation of the head causes arcuate vanes 38 to draw the material through the conduit and move it outwardly on disc 37. The inner lateral wall of the rotating head has a shoulder 4% against which a coarse mesh screen 45 is adapted to rest. This screen extends substantially the entire length of the lateral wall of the rotating head and is supported by the inner side of vanes 31 and rim 32. Superposed upon screen 45 is a fine mesh screen 46, and over the fine mesh screen is a porous felt filter 47. The fine mesh screens 46 prevents the felt from being drawn into the meshes of the screen. 7

After the material is fedinto the rotating head at its upper end it is fed over the filter by gravity'and restrained from too rapid movement by centrifugal force. The centrifugal force is great enought torestrain the downward movement of the material too much, and therefore, it is advisable when filtering certain materialsto taper the walls of the head outwardly from the top to bottom, thereby causing the centrifugal force to aid in the downward movement of the material. The moisture which is to be separated from the solid material fed into the rotating head necessity of stopping the machine periodical- V ly for the purpose of removing the solid residue. As far as the actual dryingoperation is concerned, prior machines have failed to perform with full satisfaction due to the accumulation of the material to be filtered upon a lateral wall of the cylinder, which may become packed in layers so as to prevent the moisture inthe upper layers from penetrating the lower layers and passing through the screens. I overcome all of these difficulties by removing the residue continuously with air as the machine is in operation,

as previously mentioned. For this purpose I provide a stationary hollow central shaft 51 having a plurality of'tubular arms 52 extending into close proximity to the felt filter.

These arms are provided with heads 53 having flat ends 53 capable of discharging a blast or wedge of compressed air against the solid residue on the felt to remove the same. The removed portion has a tendency to drop by gravity, but it is still under the influence of centrifugal force, which causes it to turn over and again be deposited against the felt, whereit can be acted upon by another head or air brush, as will appear clear. The arms 52 are disposed circumferentially on shaft 51 and are staggered at the same time so that upon rotation of the head the entire interior surface ofthe felt will be exposed to the arms. The ends of the arms are flat as shown at 53, and are inclined diagonally to have an action very similar to that of a plow share and aid the turning 'movement of the solid residue as it is acted upon by the air. The material striking the face of a fiat end 53 moves radially inward thereon and is turned over, thus bringing for removing'the solid residue from the felt,

also tends to propel the liquid through the V 'ter may besprayed upon the screen to assist in washing the molasses from the crystalline sugar particles. Pipes 55 extend radially inward toward shaft 51 and downwardly along shaft 51 to a distributor 56. The distributor is supplied with liquid through a common pipe 57 leading to any suitable source of liquid pressure.

The sugar or other filtered material passes progressively downwardly on the felt, and from the open lower end of the rotating head into a stationary cylinder 58, thence through a second cylinder 59 and funnel 61, into any suitable container. Cylinder 58 is of slightly smaller diameter than cylinder 59 for the purpose of inspecting and repairing the apparatus. To this end cylinder 58 is provided with a pair of laterally projecting arms 62, to which a rope 63 is secured passing over a pulley 64 and downwardly through an aperture in base 11. The endsof rope 63 are provided with counter weights 65 which normally hold cylinder 58 in its uppermost position. In order to limit the upward movement of cylinder 58 and preventing it from frictionally engaging the rotating head, a plurality of stops 66 may be provided thereon which engage against the bottom trough 35 and thus limit the movement of the cylinder.

The apparatus has been found to be highly satisfactory for separating various kinds of liquid from the solids with which they are combined. The vanes 31 mounted on the exterior wall of the filtering screens to create a suction on the exterior wall of the screens adds greatly in drawing the liquid particles through the screen. This action, in connection with the turning of the material by an air blast assisted by the plow share arms insures a thorough drying or separation of the liquids from the material to be filtered.

What I claim is new and desire to protect by Letters Patent of the United States is:

1. In a centrifugal filtering device, a rotatable head having a perforated side wall, a top plate having means for admitting material to the wall, the lower end of the wall being open, a plurality of arms extending into close proximity to said perforated wall, means for supplying a blast of air through said arms, and shares carried by the arms and through which the air blast is delivered for aiding in turning over the material collected on said wall, and removed therefrom by said air blasts.

2. In a centrifugal filtering device, a rotatable head having a perforated side wall, a top plate having means for admitting material to the wall, the lower end of the wall being open, a plurality of hollow arms extending into close proximity to said perforated wall and having flat outlet orifices extending diagonally and means for discharging air through said arms for turning over the material collected on the wall and directing it downwardly.

3. In a centrifugal dryer, a rotatable head carrying a circular porous element, means for introducing material to be dried at the top of said porous element, a plurality of means for delivering air under pressure against the porous element to progressively move the material downwardly as the head is rotated, and means in advance of eachair directing means'for spraying the material with water for the'purpose described.

4. In. a centrifugal drier, a rotatable-head, a cylindrical porous element carried by the head for passing liquids but retaining solids, means for introducing material to be dried onto said porous element near the top thereof, a material engaging member having the general shape of aplow share'and having a relatively flat and wide opening at the end thereof close to the porous element, andv means for delivering air through said opening, the air serving to remove the solid material from the porous element and bring the same into contact with the share, and the.

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