US2564595A - Whizzer separator with helical deflector - Google Patents

Description

Aug. 14, 1951 2 Sheets-Sheet 1 Filed Aug. 23, 1948 INVENTOR Joe Crites BY [AN ATTORNEY Aug. 14, 1951 J. CRITES WHIZZER SEPARATOR WITH HELICAL DEFLECTOR Filed Aug. 23, 1948 '2 Sheets-Sheet 2 Fig. 2.

INVENTOR Joe Crnes m "5505 ATTORNEY Patented Aug. 14, 1951 WHIZZER SEPARATOR WITH HELICAL DEFLECTOR Joe Crites, Larchmont, N. Y., assignor to Combustion Engineering-Superheater, Inc., a corporation of Delaware Application August 23, 1948, Serial No. 45,748

2 Claims. 1

' This invention relates to improvement in means for selectively separating finer from coarser particles of dust like material and particularly to a new and useful improvement in separating devices known as whizzer separators.

Whizzer separators may be employed, by way of example, in separator apparatus of the general type disclosed in the patents to Cook 1,783,374 and to Crites 2,169,680 in which they selectively separate finer particles from coarser particles, and in mills of the general type disclosed in the patent to OMara 2,108,609, wherein they assist in selectively determining the grade of pulverized material to be withdrawn from the mill.

The material to be separated comprises dustlike particle sizes all of which are sufiiciently fine to be entrained in a current of air or gas and are carried through the whizzer separator in flotation in the gas. The whizzer separator is interposed adjacent the outlet of a separator or mill or other apparatus from which the fines are to be separated, and rejects the heavier particles from the gas stream back into the apparatus and selectively determines the fineness or grade of material that will be carried by the gas through the outlet.

Briefly, the whizzer comprises a multiplicity of substantially radial blades mounted for rotation about an axis. A concentric plate covers the central portions of the blades to confine the gas flow through the whizzer to an annular portion adjacent the outer ends of the blades. The outer ends of the blades have heretofore been beveled and spaced in close clearance from a stationary conical deflector plate which slopes inwardly from the conduit or casing confining the gas and in the direction of gas flow through the conduit. The faster the speed of rotation of the whizzer, the finer the material that will be rejected back into the apparatus from whence it came, and by suitably controlling the speed, the grade of material carried from the apparatus in the gas stream may be determined within certain limits.

The dust laden gas in going through the whizzer is not completely separated until the whirling gas stream has passed through the whizzer into a space where there is less turbulence and a relatively smooth flow of gas along the casing Wall, that is, in the classifying zone beyond the Whizzer. The larger rejected particles or so called tailings separated in this zone must then flow back through the whizzer adjacent the deflector plate and in many cases this flow causes eX- tremely objectionable wear on the whizzer blades where this back flow occurs.

It is an object of this invention to provide new 2 and useful means for overcoming the above mentioned objection.

How the foregoing, together with other objects and advantages as may hereinafter appear or are incident to my invention are realized, is illustrated in preferred form in the accompanying drawings, wherein:

Fig. l is a vertical section, taken on line I--I of Fig. 2, through one illustrative form of apparatus employing the invention. 7

Fig. 2 is a horizontal section taken on line 22 of Fig. 1.

One application of the invention, as shown in Fig. 1, is to a pulverizing mill. The mill I comprises the upright casing 2, usually cylindrical, which is centered about the central vertical axis 3 and is supportedby foundation 5. The central vertical shaft 5 is rotatable in bearings 6 and l in the supporting structure 8 and carries at its lower end a beveled gear 9 which meshes with a pinion IE on the drive shaft II projecting horizontally from the supporting foundation 4 and driven from any suitable source of power (not shown). The spider I2 carried at the upper end of shaft 5 supports circularly arranged rollercarriers l3, each pivoted in spider l 2 at M so that the grinding rollers [5 which are supported by carriers I3 for free rotation may swing radially toward or from the shaft 5.

When this assembly is rotated by shaft 5 around the axis thereof, the rollers I5 will swing outwardly under the influence of centrifugal force against the stationary bullring I6. The material to be ground is delivered into the mill housing by any suitable means such as the pocketed feeder shown at H and falls down into the mill. The plows 43, also carried by the rotating assembly, pick up material from the bottom of the mill and deliver it back up between the grinding elements.

A fan (not shown) connected to the mill outlet conduit I9, draws air into the mill housing from the annular manifold 20 through inlet openings 2! and thence upwardly through the mill housing, this air stream picking up in suspension such material as is sufficiently finely pulverized to be carried by the air stream. The air-suspended material must first pass through the whizzer separator 22 which is interposed between the upper end of the mill and the outlet conduit l9.

The separator casing here illustrated comprises substantially an upward extension of the mill casing 2 and consists of a top or closure plate23 from the central portion of which the outlet conduit I9 extends, an upper cylindrical shell 24, and a lower joining shell 25 which connects the lower portion of shell 24 with the upper edge of mill housing 2. A gear casing 26 is supported centrally within the conical casing 25 by means of a plurality of radially extending plates 21. The rotary deflector of whizzer 22 is carried by the vertical shaft 28 journaled in gear casing 26 about the central vertical axis 3. Shaft 28 is rotated, through suitable gearing mounted in the casing 26, from the horizontal drive shaft 29 extending through one side wall of casing 25 and driven by known means (not shown) The rotary whizzer 22 comprises a closed central disk-like portion 30 from which extend a plurality of radially projecting vanes or blades 3|. The outer ends of these vanes 3| are parallel to the axis of rotation as indicated at 32 and rotate in close proximity to the inner edges of an annular deflector plate 33 extending inwardly from the casing 24.

In accordance with the invention, this deflector plate 33 is mounted on casing 24 in the form of a helix (compare left and right portions of Fig. 1) with its inner edge closely adjacent the outer ends 32 of the vanes 3| and the plate surface preferably normal to the axis of rotation of the whizzer. The pitch of this helical deflector plate 33 is about equal to the axial width of the vane ends 32 and the circular length of the plate 33 is preferably about 1% of the circumference so as to provide an overlap (shown at left portion of Fig. 2).

By this unique construction I provide a barrier by which the gas and entrained dust forwardly flowing upwardly along the casing wall 24 toward the whizzer 22 is prevented from passing around the whizzer. The helical path of the deflector plate 33, considered in the direction of the rota- ,tion of the vanes 3 I, is upstream or reverse (downwardly in Fig. 1) with respect to the forward flow (upward in Fig. 1) of the dust laden gas through the whizzer 22. Due to the rotation of the gas flow caused by the fan action of the whizzer vanes, the gas within the helical path defined by deflector plate 33 will be moved, while rotating through said helical path, in an upstream or reverse axial direction (downwardly in Fig. 1) by the deflector plate. Consequently any coarse material or tailings that has been separated out of the gas and is rotating adjacent the casing wall 24 in the zone beyond the whizzer 22 (thereabove in Fig. 1), with respect to gas flow, will be caught by the rotating gas stream entering the helical path defined by deflector plate 33 and carried by said gas stream downwardly back into the zone ahead of the whizzer (therebelow in Fig. 1) to be returned to the mill.

Obviously, the helical deflector plate 33 may if desired be extended along the casing wall 25 beyond the limits of the whizzer vanes 3 I.

The whizzer with the improved deflector plate '33 provides a continuous return of tailings to the mill without their touching vanes 3|, whereas with the use of the deflector plates employed heretofore, as disclosed in the patents referred to above, the return of tailings is often intermittent and in passing through the rotating whizzer causes excessive wear on the vanes.

Obviously, moreover, a multiplicity of helicallyshaped deflector plates spaced around the periphery of the whizzer may be used instead of the single deflector plate without departing from the spirit of the invention; in which event the pitch of each plate will at least equal the width of the whizzer blade 32.

While this improved separating mechanism is hereinbefore disclosed in combination with a mill of the well known Raymond type, it will be apparent that it can be combined in a similar manner with other forms of mills, or it may be applied to whizzer separators of the type shown in the patents to Cook 1,783,357 or Crites 2,169,680, referred to above.

I claim:

1. In a separator comprising a casing, means for causing a forward axial flow through the casing of gas entraining material to be separated therefrom, and an assembly mounted within the casing comprising a rotary whizzer having a relatively high rotational speed and through which all of the material laden gas passes forwardly from a location in advance of the whizzer to a location therebeyond, the combination of a helical deflector having one edge closely adjacent the periphery of the whizzer and extending thence radially to the casing to form a barrier against the forward passage of said material laden gas between the whizzer and the casing, said deflector being shaped to form a helical surface of at least one turn in circumferential length, the helical path of said surface, considered in the direction of rotation of the whizzer being reverse or up stream axially with respect to the forward or downstream flow of material laden gas through the whizzer whereby gas and material from beyond the deflector entering the helical path defined by said deflector will be moved axially, while rotating, in a reverse or up stream direction back to an upstream location in advance of the whizzer. 2. In a separator comprising a cylindrical casing mounted with its axis generally vertical, means for causing an upward flow through the casing of gas entraining material to be separated therefrom, and an assembly mounted within the casing comprising spaced rotary Whizzer blades between which all of the material laden gas passes upwardly from a location below the whizzer blades to a location thereabove, the combinaton of a helical deflector plate having one edge closely adjacent the periphery of the whizzer blades and extending thence radially and normal to the casing to form a barrier against upward passage of said material laden gas between the blades and the casing, said deflector plate being shaped to form a helical surface of more than one turn in circumferential length, the helical path of said surface, considered in the direction of rotation of the whizzer blades being downward in opposition to the upward flow of material laden gas through the whizzer and of a pitch equal to at least the axial width of said blades whereby gas and insufficiently fine material from above the deflector plate entering the helical path defined by said plate will be moved axially, while rotating, in a downward direction back to a location below the whizzer blades.

7 JOE CRITES.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,826,406 Sturtevant Oct. 6, 1931 1,955,960 Hirsch Apr. 24, 1934 2,010,128 Arnold Aug. 6, 1935 2,195,618 Crites Apr. 2, 1940 2,286,987 Sturtevant June 16, 1942 2,329,208 Lykken Sept. 14, 1943 2,434,037 Ebersole et al Jan. 6, 1948

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