US1666476A - Air classifier - Google Patents

Description

April 17, 1928.

A. H. STEBBINS AIR CLASSIFIER Filed Oct. 14. 1926 ATTORNEY Patented Apr. 17, 1928.

- Lu N1 ran sums P A -T- Ewr F-FICE l ALBERT .srranms,-.or LOS ANGELES, CALIFORNIA.

AIR CLASSIFIED.

a ncationmed were 14, 1926. semi 1x0441 547.

This invention relates to air classifiersiof the type in which separation ofthe 'materials-is effected by subjectingthe materials to the action of air currents that carry off the lighter particles.

It has been proposed heretofore to classify materials by passing air upwardly through the materials traveling along a screen or other apertured surface so that the air will pickup the finer particles without carrying ofithe coarser particles. 1 I

These proposed air classifiers workyery well when employed to remove fine dust-like particles from relatively large coarse particles, but whenv the/materials being treated are very fine and differ only slightly in size, it is necessary to subject them timeand 'time'againto the separating action of'gent-le air currents in order to effect the desired classification.

. The separation of these fine, dust-likeparticles can be effected by'advancing: them over the surface ofa long screen or apertured supporting surface having gentle currents-of air passing upwardly through the apertures to carryofi' the lighter particlesybuta screen or supporting surface having a sufiicient length to effect a complete classification of the materials -may occupy an excessive amount of floor space. a

The present invention therefore contemplates a construction in which the classifying chamber is given the form of-a spiral conduit and is provided with an apertured supporting surface that is 'constructedto form a spiral slide-way along whiclrthe ma-terials'to be treated travel. This spirally shaped classifier is supported in an upright position andtherefore requires only a small amount of floor-space. I

One of 'the'features of the invention -resides in the constructionwherebyair is exhausted'from the spiral classifying chamber above the apertured surface at a number of :points along the spiral chamber. 1

Another feature of the invention resides Kin the construction whereby air under pressure is forced upwardly through the apertures of the spiral supporting surface.

'Other features of the invention and novel combination of parts in addition "to-the above will be hereinafter described in con- 'nection' with the accompanying-drawings which illustrate good practical forms of the invention. i

structed in accordance sectional View through classifier of Fig. 1;:and

- matter of. thepresent inven be varied :as

sirable because the therefore preferably constructed so that In the ,drawings Fig. 1 :is .a side-elevation, -with. parts-bro- .kenaway, of .a spiral air classifier 0on Withthe present invention;

Fig. '2. onansenlargedscale is atransverse sectional 1 View through the classifier of ,F 1g. 1;

Fig. 3 on ;an enlarged scale-is a vertical .a. portion of the F'g i is a. sectional" view similar to, Fig.

3,; but/shows ;a modified construction.

The air classifier forming the subject tionv .is designed more. particularly forsuse in treating fine llHSt-Ilike particles, and ;as @above pointed out,

in order tovefi'ectively separate theseisfine particles it .is necessary to subject them repeatedly to itliecseparating action-of jgentle air-currents. This-isiidone' in accordance with 1 the present invention by .causingithe materials to be treated totravelalon a spirally wound material supporting-s11 ace or slide-way which is provided with apertures,nand .air. is caused .-to pass upwardly through the apertures and materials upon the slide-way. t0 carry off 1 the lighter :par-

holes.

porting structure for the spiral casing "10 and it also constitutesa satisfactory means for exhausting air from the casing; as -will presently appear it -is ':apparent, however,

that other meansmight be provided :-for supporting'the spirally disposed coils of the casing-an 1 air currentsvwith-in this casing.

for producing the desired rising The casing-1 01m construotedto form a closure above or about'the aperturedma- (serial-supporting surface#12 and the portion of the casing which is disposedabove. the supporting surface or slide-way 12 constitutes a --settling chamber. .The casing is it flares outwardly: as it extends upwardlyxfrom the surface 12 to increasethe-cizeof the setin a thin layer so portion of tling chamber, as will be apparent from the vertical sectional View ofFig. 3, wherein the casing is shown as formed of the wide upper wall 13, the narrow lower walll tand the side wa-ll15.

The inclination or pitch of the-spirally wound casing 10 is preferably such that when the casing is supported in a position the materials will slide downwardly along the spiral slide-way 12 under the in-.

fiuence of gravity assisted by the action of theair passing upwardly through the aper- -tures16 of the surface 12.

The materials to be treated may be delivered to the upper the Classifier by a hopper 17 having the sliding gate 18 that may be adjusted to vary the rate of feed, and the rate at which the materials-are supplied to the classifier is preferably will slide rapidly along the floor-plate12 that all particles are repeatedly subjected to the lifting action of the air. e v

The separation of the materials is effected by causing air to pass upwardly through the apertures '16 and materials traveling over the apertures to pick up the lighter particles. These rising air currents may "produced by exhausting air from the spiral casing 10 at a numberof points along its length, and this is accomplished in the construction shown by providing the passages or elongated slots 19 in the walls of the pipe 11 sothat when air is exhausted from the pipe 11 a suction vwill be produced within the casing 10 to .draw. air upwardly The slots 19 pref-' through theapertures 16.

the upper wall 13' The rising air currents within the casing 10 may be further. produced by providingthe air passage 20 formed between the apertured surface portion 2 1 of this pipe '12 and the lower wall 14, and air under pressure may be forced into this assage near the lower end of the classifier by the pipe 21 that is connected to a blast fan '22. I

*The discharge end of erably flattened out as the pipe 21 is prefconnecting the upper to a suction fan 25. The lighter particles which are picked up from the pipe 11 by from the'surface 12 "by the air currents arecarried through, the openings 19 into the pipe 11, and such particles as may settle in this :pipe are discharged through its reduced 7 7 lower end 25, while the particles that remain suspended in the alr are carried off by the suction means. The heavier particles that are not picked up by the air are directed by the slide-way 12 into the receptacle 26.

' It may be desirable to prevent the air within the casing 10 from traveling lengthplates 27 to each other and as having one slot 19 1n the space formed between a pair of baflie vertical such that the materials at 23 so that it will extend into the passage 20. Air is exhausted slide-way forwise of this spiral casing. This may be done by mounting in the casing the battle which are constructed to fit the upper portion of the casing. The baffie plates are shown as disposed at angles of withplates. As aresult of this construction the air rises more or less vertically within the upper portion of the casing forming'the settling chambers.

.In vthe modified construction of Fig. i the means for delivering air to the under side of the apertured surface under pressure is omitted, and the suction produced within the casing 10 serves to draw air from the atmosphere up through the apertures 16 of the material supporting surface 12.

Through the use of the spiral construction forming the subject matter of the present invention the materials being treated are caused to travel over an apertured surface 12 of any desired length. In this manner the particles are repeatedly subjected to the separating action of gentle air currents, and

the classification of thematerials is effected in a simple compact device that requires only a small amount of floorspace.

What is claimed is 1. A spiral classifier, comprising in combination, a vertically disposed pipe having air inlet openings in its walls, a closed casing wound spirally around the pipe to communicate with said openings and constructed to form a spiral classifying chamber, an apertured floor-plate for the casing extending spirally around the central pipe and constructed so that the materials to be treated will slide down the floor-plate, means for delivering the materials to be treated to the upper end of the spiral casing, and means for exhausting air from said pipe to draw air into the spiral chamber through the apertures in the floor plate and from the chanr her into the central pipe to cause the air to pick up and carry into the central pipe the lighter particles traveling along the floorplateu 2. A classifier, comprising in combination, a spirally wound closed casing or conduit that is supported in an upright position and constructed to form av spiral classifying chamber, an apertured floor-plate for the casing and constructed to form a spiral the materials, means for delivering the materials to be treated to the u per end of the casing to pass downwardl therein, and means for exhausting air from the casing at a multiplicity of points along its length to draw air upwardly through the apertures in the floor-plate to cause the air to pick up the lighter particles traveling along the floor-plate.

3. A classifier for classifying fine, dustlike materials, comprising in combination,

loo

a spirally wound closed casing or conduit that is supported in an upright position and constructed to form a spiral classifying chamber, an apertured floor-plate for the casing and constructed to form a spiral slideway for the materials, means for delivering the materials to be treated to the upper end of the casing to pass downwardly therein, means for forcing air upwardly through the apertures in the floor-plate to cause the air to pick up the lighter particles traveling along the floor-plate, and means for extracting ,from the conduit the air in which the lighter particles are suspended.

4. A classifier, comprising in combination, a vertically disposed pipe, a closed casing wound spirally around the pipe and constructed to form a spiral classifying chamher having air passages communicating with the interior of said pipe, an apertured floorplate for the casing extending around said pipe and constructed to form a spiral slideway for the materials, means for delivering the materials to be treated to the upper end of the casing, and means for producing air currents passing upwardly through said apertures and from the spiral casing into said pipe to pick up the lighter materials traveling along said slide-way.

5. A classifier, comprising in combination, a spirally wound closed casing or conduit that is supported in an upright position and constructed to form a spiral classifier, an apertured floor-plate supported in spaced relation to the under side wall of the casing or conduit and arranged to form a spiral slide-way for the materials and to provide an air passage below the floor-plate, means for delivering the materials to be treated to the upper end of the casing to pass downwardly therein, means for forcing air into the air passage below the floor-plate to produce air currents passing upwardly through the apertures of the floor-plate and which serve to pick up the lighter materials sliding along the floor-plate, and means for exhausting the air in which the lighter particles are suspended from the conduit at a series of points along its length. I

6. Aclassifier, comprising in combination, a spirally wound closed casing or conduit that is supported in an upright position and constructed to form a spiral classifying chamber, an apertured floor-plate for the casing and constructed to form a spiral slide-way for the materials, means for exhausting air from the casing'above the fioorplate at a multiplicity of points along the spiral casingto draw air upwardly through said apertures and cause the air to pick up and carry off the lighter particles traveling along the floor-plate, and battle plates mounted in the spiral casing to prevent the air currents within the casing from traveling lengthwise of the spiral casing.

7. A classifier for classifying fine materials, comprising in combination, a spirally wound closed casing or conduit that is supported in an upright position and constructed to form a spiral classifying chamher in which the materials beingtreated are confined from the atmosphere, an apertured floor-plate for the casing and constructed to form a spiral slide-way for the materials and positioned to provide a settling space in the chamber above the floor-plate, means for delivering the materials to be treated to the u per end of the casing to pass downward Y therein, and means for producing air currents that pass upwardly through the apertures of the floor-plate into said chamber to pick up the lighter particles traveling along the floor-plate and operable also to exhaust air from said chamber to carry ofi the lighter particles.

In testimony whereof, I have signed my name to this specification.

ALBERT H. STEBBINS.

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