US2728456A - Classifier for pulverulent solids - Google Patents

Description

Dec. 27, 1955 H. G. I YKKEN ET AL 2,728,456

CLASSIFIER FOR PULVERULENT soLIns Filed Sept. 26, 1952 2 Sheets-SheetI l 775m?. A. @025A A T TURN: Y:

Dec. 27, 1955 H. G. I YKKEN ETAL CLASSIFIER FOR PULVERULENT soLIns 2 Sheets-Sheet 2 Filed Sept. 26, 1952 INVENTORS HENRY C. L wmf/v CLASSIFIER FOR PULVERULENT SLIBS Henry G. Lykkcn and Tibor A. Rozsa, Minneapolis, Minn., assignors to The Microcyclomat Co., Minneapolis, Minn., a corporation `of Delaware Application September 26, 1952, Serial No.f311,7114

Claims. (Cl. 209-139) This invention relates to improvements in classifiers for pulverulent solid materials. In classifying pulverulent solids, according to particle size or density, one of the problems in apparatus for accomplishing this purpose has to do with maintaining separation between the classified materials, after the classification is made. This problem has especial importance in rotary type classifiers, to lwhich the present invention is most particularly directed.

In other classifying apparatus it is -sometimes desirable to provide for the introduction of cool air, or refrigerated air into the classifying zone, particularly where heat sensitive materials are being handled.

It is an object of the present invention to provide an .improved classifier wherein accurate separation of the classified materials is maintained.

It is another object of the invention to provide an `improved classifier wherein after the particles of varying particle size have been classified, they are maintained separated by an inflow of clean air or other gaseous fluid into the several departments in which the classified materials are separated.

It is another object of the invention to provide for the introduction of cool or refrigerated gaseous fluid, such as air, into the classifying zones.

Other and further objects of the invention are those inherent in the apparatus herein illustrated, described and claimed.

The invention is illustrated with reference to the drawing which is a vertical sectional view of an exemplary form of apparatus embodying the present invention.

Throughout the drawings corresponding numerals refer to the same parts.

Figure l is a vertical section through a mill and classifier embodying the features of this invention; and Figure 2 is a horizontal section taken along the line 2--2 and in the direction of the arrows of Figure 1.

Referring to the drawings, in the exemplified form of classifying apparatus it is shown combined with a mill by which solid materials are pulverized while carried by a gaseous fiuid. It will be understood, however, that the classifying apparatus may be used separately and as a complete unit apart from the mill or other apparatus wherein the mixture of pulverulent solids is produced, and that the exemplified form of apparatus is therefore not a limitation upon the invention. Referring to the drawings, in the exemplified apparatus the combined mill and classifier includes a base section shown opposite the bracket 10, a mill section shown opposite the bracket 11 and a classifier section shown opposite the bracket 12 and above the classifier section a fan chamber by means of which the gaseous fluid passing through the mill (where used) and classifier, and by which the pulverulent material is carried, is moved with its load of classified solids. The base 1li includes avertical frame 19 upon which a cover plate 13 is mounted. The base is provided with an opening 14 so as to allow access t'o the apparatus within the base.

The cover 13 serves as a mounting and closure plate States Patent O for the lower part of the mill 11. The mill 11 may be of any form desired, such as shown in Lykken Patent No.' 2,440,285, or may be of the form illustrated in the copending application of Joseph Lecher Serial No. 242,390, filed August 17, 1951. Thus, the mill may include a cylindrical housing 15 having a flange 16 that is attached by bolts 17 to the cover plate 13 of the base.

At the upper part of the cylindrical shell 15 there is pro-A vided another ange 18 which is bolted or otherwise attached to the lower ring 20 of the classifier housing 12 which also includes a cylindrical shell 21. The exemplary form of mill 11 includes a diaphragm plate 23 having a central opening 24 that is provided with a ring 25 held in place by the clamp plate 26 that is in turn fastened by the screws Z7. By changing the ring 25, the diameter of the opening 28 may be varied so as to regulate the amount of air inflowing into the base of the mill. The air or other gaseous fluid enters into the cylindrical shell 15 of the mill 11 by means of an opening 30 in the cylinder 15. The cover 13 of the base also serves to support a bearing assembly generally designated 31. lt is fastened by a clamping ring 32 that is in turn held in place by attachment screws 33. The details of the bearing 31 are within the province of mechanical design and therefore need not be described other than to state that it is adequate to support the rotating assembly of the mill (where included) and classifier at the speeds and loads involved. The bearing is preferably of the ball or roller bearing type and has provision for adequate lubrication and is sealed against the entrance of dust or grit. Above the classifier 12 there is provided a fan housing composed of the ring plate 34, the cylindrical shell wall 35, having flanges :i6-37v and a cover plate 38. The flanges 36 and 37 are held in place by the bolts 39, and thus the entire assembly is clamped together in tight relationship. The cover 3S is provided with a central pad at 40 which serves to support the upper bearing generally designated 4l which likewise is adequate for the speeds and loads involved, and is preferably of the ball or roller type and is adequately dustsealed and has provision for lubrication. Two bearings 31 and 41 serve to rotatably support the shaft generally designated 42 which has a pulley 43 preferably of the multiple V-belt type, keyed or otherwise attached to its lower end 45. A plurality of V-belts indicated by the dotted lines 47 run on the pulley to a motor or other power source not shown. The shaft 42 has an integral collar at 48 and upon it there are stacked the various hubs, discs, etc. of the mill and classifier assembly. Thus, at the bottom there is provided a hub 50 carrying the stage 51 of the mill, a portion of which is shown. The hub 50 also serves to supportA the disc 52 that carries the fan blades 53. This fan causes the entrance of air into the mill as indicated by the arrows 54-54. The inflow of air or other gaseous fluid may carry with it preliminarily crushed solids to be more finely ground, or the solids may be introduced via the entrance tube 55, a portion of which is shown in the drawings. The mill 11 may have any desired number of milling stages, such as stages 51, 56 and 57. In the form of mill shown, the stages are sep- .arated by vibratory radial discs as at 58 and capped by the vibratory disc 59, the discs herein shown being supported at their center between the hubs 50, 60 and 61. The discs 58 and 59 are preferably additionally reinforced by the smaller discs 6.2--62 and 63-63. The entire milling assembly is separated by the collar 64 from the plate 65 which forms the lowermost' part of the classifier section. Upon the plate 65 there is mounted a cylindrical drum 66 having end plates 67 and 68. The disc 6 5 is attached tothe end plate 67 by the screws 69-69 and the end plate 68is attached to the fan disc 70 by the screws 7171. Above the fan disc 70 are one or more shims 73 as needed, which are locked in place by the ring nut 75 on the threaded section 76 of the shaft. The drum 66 preferably is provided with radial vanes at 7S7 which serve to center a plurality of rings forming the classiiier section 12 of the mill. The number and variety of these classifier rings may be varied, as more fully pointed out in the copending application of Henry G. Lykken Serial No. 278,239 filed March 24, 1952, and in the copending application of Henry G. Lykkcn entitled Improved Centripetal Classifier Serial No. 306,l26, tiled August 25, 1952. Thus, the form of the classifier section, per se, may be varied, it being sufficient for the purposes hereof that the classifier shall produce a iiow of gaseous huid as indicated by the arrows Sil-80, by means of which particles uniformly classified as to size and/or density, are carried into the spaces between the radial blades 78 on the drum 66. Thus, the plate 65 is provided with radial slots at S2 adjacent its edge so as to produce a distinct stirring and inflow of the mixture of size particles in the gaseous flow, this inflow being indicated by the arrows S5-S5. Above the plate 65 there are one or more shim rings 86 as needed and upon the uppermost of such shims there is positioned the rings S7 having the radial blades 83 thereon. Radially inside the radial blades SS there are provided the wier rings 89 and 99 separated by the plurality of separating studs 91 so as to leave a space at 92 for the inflow as shown by arrows Sti-S9. Upon the plate 9d is stacked another ring 95 likewise having radial blades 26, and above it additional wier plates at 97 and 98, likewise separated by the studs 99. This stacking is repeated until the entire space is filled, whereupon the stack is capped by the ring 1112 which in turn is capped by the ring 103 which may, if desired, carry small fan bieding 104 for a purpose to be described. Above the plate 194 it there is stacked a cylinder 105 to which is welded the ring 166 against which the lower edges of the fan blades 108 rest, the fan blades being carried at their upper edges by the fan disc 70.

Between the plates 163 and 106 there are provided two stationary rings, ring 119 which is fastened to the plate 34 and a ring 111, which is fastened to the short cylinder 112 which is in turn fastened to the ring 113 that is held in spaced relation by the spacer ring 114, the same being welded or otherwise fastened in place to wall 34. The f' plate 34 of the fan housing is provided with one or more apertures 115 covered by the slide gates 116 by means of which more or less of the aperture opening may be uncovered. The fan housing has an opening from which the gaseous fluid, carrying particles of a prescribed size or density, are discharged.

The inflow of air or other gaseous iluid, as shown by the arrows 85 carries with it a mixture of particle sizes and particle densities, the action of the radial slots S2 in the plates 65, and of the radial blading 88, 96, etc.

is to produce an intense swirling and admixture of particle sizes within the space 122 between the inside of the classiiier housing shell 21, and outside the rotor composed of rings S7, 9S, etc. and blades S8, 96, etc. The radial blading causes swirls of materials to be produced between successive blades and due to the iniiow of gasecus duid, as shown by the arrows Sil-80, particles pass into the axial space between the radial blades 78. The fan blading 168 and the overall resistance through the mill and classifier produce a controlled ow of gaseous fluid, as shown by arrows 54, 85 and $0 and delivery through discharge opening 120, as shown by the arrow 125. Consequently, the gaseous flow carrying particles of a given size or density, classiiied precisely, flows via arrows into the space above plate 113 and below plate 38 of the fan housing which forms a delivery chamber.

In order that coarse particles, which do not pass according to the flow S0, may not pass into the fan chamber 34-35-38, air is introduced via openings 115 (slides 116 being then open), thus flowing as indicated by the arrow 127 into the space forming a gas entrance or air feed gland between the plates 110-111. Part of this clean, fresh and uncontaminated air ows out through the space between plates 106 and 111, as shown by the arrow 128 and hence holds the already classified particles in the fan chamber 34, 35 and 3S, and part of the flow passes, as shown by the arrow 129, and is propelled by the fan blades 104, where used, back into the classifier chamber 12, thus causing the coarse particles to be driven back :into the classifier.

The fan chamber 34-3538 may be replaced by an external suction fan, in which case the separation in the form of the air entrance gland 11G-111, is then between the classier 12 and the duct work carrying the air and its load of already classified fine particles. Likewise, unclassified mixtures of coarse and fine particles in a gaseous flow may be introduced into the classifier from an external source, rather than from an integral mill as herein exemplified.

As many apparently widely different embodiments of this invention may be made without departing from the spirit and scope thereof, it is to be understood that we do not limit ourselves to the specific embodiments herein.

What we claim is:

l. An improved rotary classifier comprising a closed cylindrical classifier casing having an opening at one end forming an inlet and an opening at the other end forming an outlet, a delivery chamber adjacent but slightly spaced apart from the outlet, a rotor journalled for rotation within the casing and having one portion extending through the outlet opening of the casingand into the discharge chamber, spaced radial classifier rings mounted on said rotor within the casing, an annular axial passage in the rotor communicating with radial passageways between the classifier rings and with said delivery chamber for flow therethrough of gaseous fluid containing classified solid particles, means for inducing a lowered gaseous pressure in said delivery chamber, and a gas entrance gland between said casing and delivery chamber for supplying clean gaseous fluid to said casing and said delivery chamber.

2. An improved rotary classifier comprising a closed housing having an inlet at one end and discharge outlet at the other end, a pair of walls across the housing separating it into three successive chambers, namely a classification chamber, an air feed chamber and a delivery chamber, said walls being provided with generally aligned holes, a classifier rotor extending from the classification chamber and through said holes and air feed chamber and into said delivery chamber, the edges of said holes being closely adjacent the rotor, said rotor having a passageway generally axially therethrough from the classification chamber to the delivery chamber, said passageway being closed for the extent of its passage through the air feed chamber and out of communication therewith, means for inducing a flow of gaseous fluid from the classification chamber through said passageway to said delivery chamber, said air feed chamber being provided with an opening for the introduction of clean gaseous fluid thereinto for supplying clean gaseous fluid to said classification chamber and delivery chamber.

3. The apparatus of claim 2 further characterized in that fan means is provided on said rotor, said fan means being located in said classification chamber adjacent the hole in the wall separating said classification chamber from the air feed chamber for inducing a flow of air axially in respect to said rotor and through said hole from the air feed chamber into said classification chamber.

4. The apparatus of claim 2 further characterized in that the opening in said air feed chamber for the introduction of clean gaseous fluid thereto is provided with means for varying the size thereof.

5. An improved classifier comprising a cylindrical housing having end closure plates, one of said end closure plates having an inlet opening therethrough and the other enclosure plate having an aligned outlet opening theredrical housing and through said portion extending through 5 said outlet opening, a fan mounted on the rotor, a fan casing around said fan mounted adjacent to but slightly spaced apart from the cylindrical housing, and an air feed gland between said fan casing and cylindrical housing provided with spaced plates extending into close proximity with the closed passageway portion of the rotor extending through said outlet opening, said spaced plates forming a chamber having an opening to a source of uncontaminated gaseous uid for introducing said fluid into said cylindrical housing and fan casing adjacent to the closed axial passageway.

References Cited in the le of this patent UNITED STATES PATENTS 919,291 Moodie Apr. 20, 1909 1,876,516 Fraser Sept. 6, 1932 1,933,606 Sturtevant Nov. 7, 1933 2,092,307 Gaffney Sept. 7, 1937 2,304,264 Lykken Dec. 8, 1942 FOREIGN PATENTS 219,647 Great Britain Oct. 9, 1924

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