US2206981A - Air separator - Google Patents

Description

y 9, 1940- T. J. STURTEVANT 2,206,981

AIR SEPARATOR Filed July 15, 1.938 4 Sheets-Sheet 2 'INVENTOR' Wm rsz wze l/an'C" ATTORN July 1940. T. J. STURTEVANT AIR SEPARATOR Filed July 15, 1958 4 Sheets-Sheet 5 ?0 PEI 972 INVENTOR WamasJlSZZv-Ze/anfi BY ATTORNEY J y 9, 1940- T. J. STURTEVANT AIR SEPARATOR Filed July 15, 1958 4 Sheets-Sheet 4 INVENTOR 7 Tfifizrfcf/MT 7 BY ATTORN E Patented July 9, 1940 UNITED STATES PATENT OFFICE AIR SEPARATOR Application July 13, 1938, Serial No. 219,015

11 Claims.

This invention relates to separators of the whirlwind type for sizing or grading material, the general principles of which are well known in this art. For an example of a separator of the general type to which this invention relates see my Letters Patent of the United States No. 2,030,612, dated February 11, 1936.

In this type of separator, a separating chamber and a surrounding collecting chamber are in communication through top and bottom openings, a main circulating fan above the top opening causing the air to circulate upwardly through 'the separating chamber and downwardly through the collecting chamber in a closed circuit. The material to be graded is introduced into the separating chamber and centrifugally into the path of the rising air current. The fines, or that part of the material that can be lifted and flow through rejective means, such as a fan, located between the zone of distribution and the top or outlet opening of the separating chamber, pass to the collecting chamber to be delivered through an outer cone to a fines outlet while the tailings, or rejected heavier particles, gravitate downward past the bottom or air inlet opening of the separating chamber and are delivered through an inner cone to a tailings outlet.

principal object of this invention is to extend the control of the finished particle size, i. e. the fineness of the particles that pass down through the collecting chamber and to the fines outlet. A maximum or complete control of the fineness of the product is exercised through factors determined by the power of the rejector fan to oppose the main fan and thus control the volume of air moving in a closed circuit.

These include the size of the rejector fan, which may be taken to embrace the number or spacing of its vanes, and particularly the relative diameters of the fan and of the top opening through which the air stream is drawn upwardly.

It is important that changes in the factors that control. the fineness of the product may be made while the separator is in operation or at least with only a very brief cessation of operation. Accordingly-a feature of this invention resides in providing the separator chamber with as large a top opening as is practical, preferably from about 80% to about 90% of the area of the largest or top diameter of the chamber, and with a rejector fan sweeping just below said opening of the same or only slightly less diameter, preferably in combination with a sliding plate valve for said top opening, under control ofthe operas ator from outside the separator, constructed to provide an adjustment range from no overlap of the vanes of the rejector fan and no overlap of the top opening to a. large overlap of said vanes and a considerable reduction in the area of the top opening.

Since a very wide range of control of the finished product can be obtained by changing the spacing of the vanes of a rejector fan, as by decreasing the number of vanes as disclosed in my prior Patent No. 2,030,612, it is important to continuous operation of the separator that an adjustment of this naturesbe permitted in as short a time as possible. Heretofore it has been necessary to wait for some hours for the separator to cool before a workman can enter the separating chamber to remove or replace the rejector fan vanes as may be required for the material next to be separated. A further feature of the invention, which permits practically continuous operation, resides in providing substantially instantaneously shiftable or removable rejector fan vanes on the baflle which carries them, through means accessible by reaching in through a manhole in theouter cover while the separator is still too hot to enter.

To the accomplishment of the above named object of the invention and such others as may hereinafter appear, as will be understood by those skilled in the art, the invention comprises the features and combinations of parts having advantages in improving the performance of separators of the type hereinbefore generally described as will be apparent from the following de-. tailed description thereof when read in conjunction with the accompanying drawings illustrating the preferred form of the invention, in which Figure 1 is a view, in vertical section, through a separator of the whirlwind type illustrating one form of the invention herein claimed;

Fig. 2 is a view, diagrammatically in plan, of the head of a separator according to this invention;

Fig. 3 is a view, in plan, of a portion of the preferred form of the rejector fan, shown with its vanes evenly spaced;

I Fig. 4 is a view, in plan, of some of the vanes of the rejector fan the vanes being shown adjusted to double their spacing and to reduce their number by one-half;

Fig. 5 is a view, in section, across the preferred rejector fan on the recessed line 55 of Fig. 3; Fig. 6 is a view, in plan and omitting the inner mechanism of the separator except therejector fan vanes, of some of the sliding plates of the plate valve, at the top opening of the separating chamber, adjusted to their outermost or open position.

Fig. 7 is a view similar to Fig. 6 but with the plates of the valve adjusted inward to their fully closed position relative to said top opening of the separating chamber.

Fig. 8 shows a front-edge view of a single plate of the plate valve; and

Fig. 9 is a detail view, in elevation, showing how the vanes of the rejector fan disclosed in the Fig. 1 assembly (but also other fan types) may be mounted for quick removal or replacement.

Referring to the drawings the separator shown therein, as an illustrative type of air separator in which the invention may be embodied, comprises an outer casing I consisting of a drum'having a cylindrical wall 3 closed by a flat head 5 and having a cone 1 at the lower end thereof terminating in a discharge spout 9. Within and spaced from the outer casing is an inner casing or drum consisting of a cylindrical wall l3 having a marginal head i5 providing a centralized outlet or top opening [1 therein and having a conical shell 19 at the lower end thereof. The inner casing may be supported by suitable brackets 2| between and secured to the walls 3 and I3.

Beneath and spaced from the conical shell 13 is a cone 23 provided with a discharge spout 25' which extends laterally through an opening in the cone I of the outer casing. The cone 23 may be supported by plate struts 21 between and secured to it and the cone 1,

The inner casing forms a separating chamber 30, and the annular space between the inner and outer casing walls 3 and I3 forms a settling or collecting chamber 32. The space between the conical shell l9 and the cone 23 serves as an air inlet opening for the circulation of air from the settling chamber into and through the separating chamber. Located at this inlet is a series of adjustable vanes 33 pivotally connected to a ring 34 secured to and projecting outward from the lower edge of the conical shell IS.

The materials to be graded are delivered to the separating chamber through an inclined delivery chute 35 leading to a conical feed hopper 3'5 depending'from the head 5 and having a lower cylinc' :al neck 31 extending down centrally into the s .lrating chamber 30 through its top opening l..

Mr nted on the head of the outer casing are a p: of channels 38 supporting a housing 40 extending downward through the casing head 5 into the hopper 36 and having upper and lower bearings. A vertical driven shaft 4| is journalled in said bearings. A bevel gear on the driven shaft, within the portion'of. the housing above the head 5, meshes with a bevel pinion on a horizontal driving shaft 44 journalled in suitable bearings and carrying a pulley driven by a motor (not shown) that may conveniently be mounted on the casing cover.

The driven shaft ll extends down from its bearing housing centrally of the feed hopper 36-31, its lower end projecting therefrom into the separating chamber 30. This lower end carries a distributor, toward the lower limits of the classifying zone, comprising a plate hub 43 and a plurality of segmental plates 50 secured to the hub and to each other in a manner to provide substantially smooth faces, or so as to produce very little air disturbance as the distributor rotates;

Projecting up from the margin of the hub 43 are posts 51 carrying a sleeve 52 surrounding the cylindrical neck 31 of the feed hopper and provided with a lower horizontal flange 53 and an upper cone-flange 54 extending into a chamber 58 between the cover plates 5 and 15 communicating with the collecting chamber 32. Secured to the cone-flange 54 are a plurality of arms 55 each carrying a vane 55 of thecirculating fan. The circulating fan rotates clockwise, as related to Figs. 6 and 8, in the chamber 58 and its vanes 56 may be radially adjusted on the supporting arms 55 by the provision of several equally spaced bolt holes indicated by the bolt heads on Fig. 1.

Above the distributor 50, as is usual in'this type of air separator, is a circular baflle 55. In this instance the baflie carries a circular series of rejector fan vanes at its upper face each set radially and projecting beyond its edge. The baille 60' is located well up in the zone of selective action or classification intermediate the distributor 55 and the top opening 11 of the separating chamber 3|! such that the upper edges of its fan vanes sweep in a plane which is substantially that of the under face of the ring cover l5 of the separating chamber.

Before describing the forms that the rejector fan may take in combination with other features to secure an extended control of the finished particle size or fineness over that heretofore attainable, attention is called to the size, in the illustrated air separator, of the outlet opening 11. The cover 15 of the separating chamber 30 consists of merely a marginal ring-plate which is comparatively narrow and according to this invention is purposely so made in order to provide a top opening 11 having an area approximating 80% to 90% of the area of the largest diameter of the inner cylindrical casing II. A feature of the invention consists in a rejector fan of the same or very slightly smaller diameter than the maximum diameter of the top opening for its minimum rejective power. Adjustments for special conditions are provided as will appear hereinafter.

As shown in Figs. 1, 6, 7 and 8, the top opening I 1 is provided with a plate-valve comprised of a series of overlapping sliding plates 52 above the ring cover plate l5, each controlled, as to its radial position relative to the peripheral edge of the opening 11, from outside the separator through a sliding rod 53 secured thereto and projecting radially outward through a stufling box guide, shown conventionally, at the outer face of the casing 3. Such a valve is disclosed, in principle, in my said Letters Patent of the United States Nos. 1,615,558 and 1,703,833. The improved plate-valve construction for carrying out the objects of this invention will be presently described.

The opposing power of the rejector fan to the main fan depends, for any fixed number of vanes, to a large degree on the size of the top opening as compared to the diameter of the rejector fan. In the present construction this variation is controlled by the amount of the overlapping, in an inward direction, of the sliding valve plates beyond the edge of the ring-cover l5 and consequently over the vanes of the closely adjacent rejector fan. As herein disclosed there is a range from. nooverlap of the fan vanes when the valve plates are withdrawn clear of the top opening to a comparatively large overlap when the valve plates are moved to their farthest inward position. With no overlap the rejector fan operates at its minimum power for the coarsest classification of material. The maximum overlap steps up the power of the rejector fan to its maximum for the finest classification. 1

In Figs. 6, and 7 the plate valve is shown adjusted to provide the maximum and minimum slightly overlapping the rejector fan vanes. The

extreme inward position of the valve plates, as shown, is effective to reduce the area of the top opening through a range which is ample for all commercial purposes. As the plate-valve is closed, the rejector fan vanes are increasingly overlapped. When the plate-valve is closed to its extreme inward position, the rejector fan vanes (of the size disclosed in the accompanying drawings) are overlapped or baffled for about onehalf of their normal efi'ective length as is indicated by the two vertical arrows on Fig. 1, one above each of the rejector fan vanes there shown. The above described control of the power of the rejector fan to oppose the circulating fan gives a maximum control of the air current in a closed circuit and is highly advantageous because it may be employed while the separator is in operation.

Referring to Figs. 6 and 8 it will be seen that each valve plate is flat and consists of a main portion 64 conveniently similar in shape to a section cut from an annulus except that its end edges are parallel, and a wing portion 65 of like shape but shorter and lapped on one end of the upper face of the main portion (Fig. 8). The concave inner edge of each portion is struck from the same center and together they form an arc of a circle of the same diameter as that of the top opening I! from the separating chamber. All of the valve plates 62 are alike in that the wing portions 65 are lapped on the same end and all are of the same size. When the valve is fully open (Fig. 6), each wing portion overlaps merely a corner of the 'main portion of the adjacent plate 62, but as the plates are slid inward between the spaced, sector-shaped surface plates 66 and past the peripheral inner edge l'la of the top" opening 11, this overlap increases until adjacent inner edge corners of the main portions of the plates 62 practically abut at the maximum closing of the valve (Fig. 7).

The plate valve may be quickly adjusted from outside the separator, by means of the control rods 63, to any desired overlap of the circular series of rejector fan vanes to suit practically any given condition of classification of the material being separated. The range of adjustment afforded, when combined with a rejector fan having a vane tip diameter at least that of the top opening from the separating chamber, is adequate for variations in'the classifications of common cement and like materials which range from 1500 to 1900 surface area of the fines recovered.

The preferred construction of an adjustable rejector fan is illustrated by Figs. 3 to 5. The

lower flange 53 of the sleeve 52 forms a hub to' the under face of which the circular bafile plate 60 is connected. The upper face of the hub 53 has radial stifi'ening ribs 61, one of which is omitted at the right of Fig. to permit illustration in full lines of the vane adjusting means.

The hub 53 is under-rabbeted at its edge to overlie the inner edge of an annular rotative plate 68 which rests on the battle plate 60. There are an even numberof radially set fan vanes one-half of which. the vanes 10 (Fig. 5) are each supported in a vertical position on an angle iron II secured to the margin of the baiile plate 60, and the other half of which, the vanes 12 (Fig. 5) alternating with the vanes 10, are each supported in a vertical position on an angle iron 13 secured to and movable with the rotative annulus 68. Properly both the fixed and movable vanes are of the same size and all should project beyond the baffle plate to the same extent so that the vane-tip diameter of the rejector fan is constant on any diameter.

As has been stated the power of the rejector fan to oppose the power of the circulating fan depends, for any fixed number of vanes, in a large degree on the overlapping of the sliding valve plate 62 over the vanes. A very wide range of control of theflnished product can be obtained by a variation of the number of vanes in the rejector fan, as the nearer the vanes are together the more difficult it is for particles in the rising air stream. to pass out at the top opening, whatever its size, without being batted out by the fan toward the wall of the separating chamberwhere they drop down, possibly to be lifted again by the air current or properly to pass on to the tailings outlet. The same effect on the rejective power of the rejector fan as is obtained by reducing the number of vanes may be obtained by retaining the whole number of vanes but by varying their spacing because it is those vanes that are more widely spaced which determine the effectiveness of the fan to bat the rising particles outward.

The reason for mounting one-half of the rejector fan vanes on the rotative annulus 68 will now be clear because, assuming the fan is set up under a condition of use requiring equal vane spacing (see Fig. 3), as the annulus 68 is rotated in one direction it carries its alternate movable vanes 12 as a unit toward the fixed vanes 10 secured to the baffle plate 60 and consequently increasesthe effective vane spacing. Means is provided to so rotate the annulus as to enable the operator to-set the movable vanes relatively to the fixed vanes for giving a power range to the rejector fan equivalent to the use thereon of one number of vanes to double that number. Such means, as illustrated. consist of a turn buckle 15 having its forward (in the direction of rotation) end 16 pivotally mounted on the outer end of one of the radial hub stiffeners 61 and its rear end 11 pivotally mounted on a thrust strut 19 carried by the annulus 68 and extending between the mounting angle irons 13 of two adjacent movable vanes 12. A manhole 80 (Fig. 2) is provided in the cover 5 of the outer casing I so that,

after the rejector fan has been rotated to bring the turn buckle 15 beneath the manhole, a workman may reach in immediately, or without waiting for the separator to' cool sufficiently for him to enter the separating chamber, and screw the turn buckle up or down as may be required to (Fig. 4) the result is as though half the vanes were in use. In between these extremes there are numberless variations which will affect the rejective power of the 'vanes. Such adjustments according to the teaching of this invention are eifective for classifying material within a range of 2000 to 3000 surface area of the fines recovered.

The manhole may be used, with the same view to saving time for a rejector fan adjustment, with the construction of rejector fan illustrated in the assembly drawing of Fig. 1 and the detail of Fig. 9. In this instance the baille hub 53 and bailie plate 60 are the same as hereinbefore described but each of the fan vanes 82 is in a fixed radial position in circular series overhanging the marginal edge of the baflle. While fixed as to their angular position in the series of vanes each vane'is, nevertheless, quickly removable when brought within range of the workman at the manhole. To this end, as shown, two vane bolts 84 (Fig. 9) are passed through holes in the vertical face of the supporting angle iron 85 havingtheir heads welded to the iron to hold them in definitely spaced position. Each vane is provided with two key-hole slots at its lower margin. Each slot comprises a larger hole 88, of a size to permit the nut of a bolt 84 to pass through, and a communicating smaller hole or slot 92 dimensioned to fit or seat on a bolt 84. A vane is removed by merely loosening, not removing, the nuts 90 whereupon by a right-line slip past the bolts 84 the vane is brought to a position where it can be withdrawn from the bolts. These operations, substantially instantaneous, are reversed for mounting a vane.

This provision for adjustment of the power of the rejector fan is efficient but not to such a degree as when the combination of fixed and movable vanes is employed. Starting with an even number of vanes the power of the fan may be halved, quartered, eighthed, etc. that is, decreased by regular steps as contrasted to the variable adjustment gradations obtained with the preferred form of the rejector fan. In both forms of the rejector fan its rejective power may be adjusted from outside the separator. In either case, and notably with the preferred form, a complete classification range is obtained without the necessity of shutting down the separator. As an example of a practical range, say 1500 to 3000 surface area of the fines recovered and referring to classifying both common and highearly cement, 1500 to approximately 2000 of said range may be covered by a plate valve adjustment in the combination illustrated, and 2000 to 3000 of said range may be covered by a rejector fan vane adjustment. Those skilled in the art will recognize that replacement of worn vanes of any type of fan is facilitated by this invention.

In the accompanying drawings the relative positions of some of the adjacent parts is exaggeratedv in order to present with clarity the preferred constructions, the principle involved and consequent scope of the invention being made clear by the description and the appended claims.

It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation and it is not intended to limit the invention beyond the terms of the several claims hereto appended as considered in view of the prior art and the requirements thereof.

What is claimed as new, is:

1. In an air separator of the type described having a central rotary shaft within the separating chamber, a distributor mounted on said shaft, a baiiie rotated by said shaft above said distributor having a circular series of radiallyset fan vanes at its margin which, under one condition, may be equally spaced circumferentially, certain of said vanes being mounted on said bame in fixed positions and certain others being mounted on said baille for circumferential movement along its margin, and means for bodily sliding said movable vanes over said baflle relatively to the fixed vanes to a position creating unequal circumferential spacing in the series of fixed and movable vanes.

2. In an air separator of the type described having a central rotary shaft within the separating chamber, a. distributor mounted on said shaft, a baille rotated by said shaft above said distributor having a number of radially set and equally spaced fixed fan vanes at its margin, an equal number of radially set fan vanes each circumferentially movable along the margin of said baille and alternating in series with said fixed vanes, and means for bodily sliding each movable vane from a mid-position between adjacent fixed vanes either toward or to a position against one of them, and vice verse, to vary the spacing between pairs of vanes of the series.

3. In an air separator of, the type described having a central rotary shaft within the separating chamber, a distributor mounted on said shaft, a baille rotated by said shaft above said distributor having an even number of radially set fan vanes at its margin, one-half of said vanes being fixed to said bailie and uniformly spaced clrcumferentially, the other half of said vanes being movable circumferentially along the margin of said baflle one in each of the spaces between pairs of said fixed vanes, and means'for bodily sliding each movable vane toward or from a fixed vane within said space between adjacent fixed vanes.

4. In an air separator of the type described having a central rotary shaft within the separating chamber, a distributor, mounted on said shaft, a battle rotated by said shaft above said distributor having an even number of radially set fan vanes at its margin, one-half of said vanes being fixed to said baiiie and uniformly spaced circumferentially, the other half of said vanes being bodily movable circumferentially along the margins of said baflle one in each of the spaces" between pairs of said fixed vanes, and means for simultaneously shifting the positions of said movable vanes within the spaces between adjacent fixed vanes.

5. In an air separator of the type described having a central rotary shaft within the separating chamber, a distributor mounted on said shaft, a baille rotated by said shaft above said distributor having an even number of radially set fan vanes at its margin, said vanes being equally spaced under one condition of use, alternate vanes being mounted on the baffle for bodily movement as a unit along the margin thereof. and means for shifting said movable vanes relative to adjacent vanes to increase the eifective vane spacing while maintaining the spacing and on said shaft above said distributor, said baiiie having an annulus rotatively mounted and centered on the upper face of said cover-plate in position to leave a substantial projecting margin of said cover-plate, a spaced series of radially set, fined fan vanes on said marginal portion of said cover-plate, a second spaced series of radially set fan vanes, one between each pair of said fixed fan vanes, mounted on said annulus at its upper face, and means for rotating said annulus relatively to said cover-plate to adjust said second series of fan vanes within limits determined by the spacing of adjacent fixed fan vanes.

7. In an air separator featured as described by claim 6, a turn buckle having one end secured to said baflie and its other end secured to said annulus constituting the means for rotating said annulus relatively to said cover-plate.

8. A rotary baille for the rotary distributor within the separating chamber of an air separator of the type described, said baffle comprising a hub and a circular cover-plate secured thereto, there being an annular ring-plate carried by, centered and secured to the upper face of said baflie coverplate for angular, rotative movement relatively thereto, a circular series of fan vanes at the margin of said baiile supported by and movable as a unit with said annular ring-plate, and means under control of the operator for rotating said ring-plate through a limited arc of said coverplate.

9. A rotary baflie within the separating chamber of an air separator of the type described, comprising a hub, a circular cover-plate secured thereto, a circular series of fan vanes at the outer margin of said cover-plate, an annular ring-plate at the inner margin of said cover-plate movable in a circular path concentric to the hub, alternate vanes of said series being mounted on the ringplate, and a motion-transmitting device interposed between the ring-plate and cover-plate operable for shifting the position of said vanes mounted on said ring-plate relatively to the remaining vanes of the series.

10. In an air separator of the type comprising a covered outer cylindrical casing and a marginally covered inner cylindrical casing, said casings being spaced from each other circumferentially and between their covers, said top chamber containing a rotary circulating fan, said cir-, cumferential space forming a settling chamber, and said inner casing forming aseparatingchamher, there being a bottom inlet between said latter two chambers for the circulation of air in a closed circuit, characterized by a centralized, circular top opening within the marginal ring-cover of said separating chamber and a rotary rejector fan lying across the rising stream of air passing to said top opening and having a vane-tip diameter approximately equal to butnot greater than that of said top opening, said rejector fan comprising a centralized circular baflle of substantially less diameter than that of said top opening, said baiile supporting a circumferential series of spaced vanes each in the form of a blade having a free portion of' its length projecting radially beyond the edge of said baflle, alternate vanes of said series being movable circumferentially of said baflie, all in combination with means for simultaneously moving all of said circumferentially movable vanes toward and from adjacent vanes, an annular plate valve associated with said top opening and adjustable to change its effective diameter, and means for adjusting said valve from no overlap of the portions of said rejector fan vanes projecting beyond the baflie when it is fully open to a substantial overlap thereof at the smallest adjusted diameter of said top opening effected by said valve.

11. In an air separator of the type described having a central rotary shaft within the separating chamber, a distributor mounted on said shaft, 'a bafile rotated by said shaft above said distributor and supporting a circumferential series of fan vanes at its margin, said vanes being, in one instance, spaced equally from one another circumferentially and alternate vanes of said series being movable circumferentially of said baifle, and means for simultaneously moving all of said circumferentially movable vanes above said shaft as an axis of rotation toward and from adjacent vanes.

THOMAS J. STUR'I'EVANT.

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