Magnetic dispersion head and dryer

BACKGROUND OF THE INVENTION

This invention relates to a combined magnet and heated air dispersion device capable of being used in a storage hopper for granular material. More particularly, this invention relates to an improvement in an apparatus for treating a flow of granular nonmagnetic material which contains a small percentage of magnetically permeable material. Still more par- 1 ticularly, this invention relates to an apparatus for use in a storage hopper for granular plastic material which provides magnetic protection against tramp iron and other magnetically permeable impurities while simultaneously providing effective dispersion of heated air to dry the flowing material.

It has long been a problem in the art of manufacturing articles from granular material to provide means for extracting moisture from the material, particularly where moisture may have an adverse effect on subsequent treatment of the materi- , al. A traditional method of drying material is to place the material on a suitable heated pallet and to remove the moisture from the material through the judicious application of heat. Such an arrangement, however, is inefficient, primarily because of material handling costs and ineffective disper- : sion of the heat through the material.

Another old solution to the problem of drying granular material, such as plastic, is to transfer the material through a hopper which includes a drying apparatus. A typical plastic hopper and dryer combination arrangement utilizes a perforated metal cone through which heated air is dispersed to dry the granular material. Such an arrangement, however, is unsatisfactory in view of its deficiencies in homogeneously dispersing heat throughout the hopper to effectively dry the material. Moreover, the dispersion head requires an excessive volume of space. Such an arrangement, which uses a generally cone-shaped heater head, may be seen in U.S. Pat. No. 2,641,848, issued on June 16,1953 toO. C. Wilson.

Still another problem in the handling of the generally nonmagnetic, granular, or powdered material, such as may be used in molding plastic materials, is to remove effectively magnetically permeable material from the nonmagnetic material. Such magnetically permeable material may include impurities known in the art as tramp iron resulting from machine turnings, metal particles in reclaimed plastic, and the like. Arrangements are known to the art for classifying metal powder, for example, by the use of a magnetic separator. An example of such a material segregator utilizes a magnetic device comprising a permanent magnet suitably positioned in a recovery hopper so that magnetically permeable material passing near the magnets may be segregated from nonmagnetic material. Another example of a magnetic separator is a grate magnet without heated air dispersion means as may be seen in U.S. Pat. No. 2,733,812 issued on Feb. 7, 1956 to R. C.

Hoff. . .

A solution to the problem of drying granular or powdered material while at the same time removing tramp iron or other magnetically permeable material from the nonmagnetic material is found in a magnetic dispersion head according to the invention which is capable of being used in a conventional plastic hopper. In this respect, it is an attribute of the invention that the dispersion head be designed to replace prior art perforated metal cones with the attendant advantages available from such a replacement. Such replacement devices must, however, assure an even flow and adequate dispersal of heated air through the granular material so that the air flow remains essentially uniform while providing thorough exposure to the material to assure complete drying. Still another feature of such replacement dryers rests in their ability to utilize existing hopper construction and existing sources of heated air. Moreover, such replacements are convenient to remove for cleaning the tramp metal from the tubes.

SUMMARY OF THE INVENTION

Directed primarily to the efficient, inexpensive and convenient solution to the deficiencies and shortcomings of the prior art solutions to the problem of drying a flow of generally nonmagnetic material which contains a small percentage of magnetically permeable material and effectively segregating the magnetically permeable impurities from that material, the improvement according to the invention comprises means for dispersing the flow of material into a plurality of flow paths. Means are provided for introducing heated air to the apparatus for drying the flow. Means are also provided for dispersing at least a portion of the introduced heated air into each of the plurality of flow paths so that thorough and complete drying is obtained. Magnetic means are located in a spaced relationship to each of a plurality of flow paths to remove magnetically permeable impurities from the flow of material.

In particular, the apparatus, capable of being readily positioned in the conical aperture discharge head of a conventional hopper, comprises a plurality of spaced, horizontally disposed inverted, generally V-shaped diverter members so arranged that the spaces between the diverter members form a plurality of flow paths for the granular material. The magnetic means include a plurality of generally cylindrical permanent magnets secured in a generally parallel relationship to each other and located in the flow path for the granular material so that magnetically permeable material in the flow may be segregated from the nonmagnetic material.

It has been found advantageous to position the permanent magnets with like magnetic poles adjacent one another to alleviate the problem of magnetically permeable materials being retained in the relatively strong magnetic field between unlike poles of adjacent magnets and, thus, bridging the adjacent magnets during the extraction process. When such bridging occurs, the system loses its efficiency for magnetically collecting and segregating those impurities.

The generally cylindrical, permanent magnets include a plul rality of smaller, generally cylindrical, permanent magnets in an axially spaced relationship within a stainless steel tube. When so provided, unlike poles of adjacent axially spaced magnets within the cylindrical permanent magnet are placed in juxtaposition.

> Accordingly, it is a primary object of this invention to combine magnetic protection against tramp iron or other magnetically permeable material with adequate dispersion of heated air into a flow of generally nonmagnetic material in a conventional hopper.

It is a still further object of this invention to provide an apparatus capable of drying granular material and magnetically removing magnetically permeable impurities form that granular material.

It is a still further object of this invention to provide an improvement in a conventional drying apparatus.

It is a still further object of this invention to combine tramp iron protection with an improvement in a conventional drying apparatus.

It is another object of this invention to provide an apparatus for drying a flow material while simultaneously segregating magnetically permeable materials from the flow.

Further objects and aims of this invention will be apparent from a perusal of the accompanying drawings and a review of the detailed specification which follows.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of the improvement according to the invention.

FIG. 2 is a view of a conventional prior art plastic hopper using the apparatus according to the invention.

FIG. 3 is a partial sectional view taken along line 3—3 of

FIG. 1. , , .. . .

FIG. 4 is a partial cross-sectional view taken along line 4—4 of FIG. 1.

3,630,352

FIG. 5 is a partially sectioned view taken along line 5—5 of FIG. 3.

DESCRIPTION OFTHE PREFERRED EMBODIMENTS

In FIGS. 1 and 2, a combination magnet and heated air dispersion device according to the invention is shown generally at 1. FIG. 2 depicts a conventional prior art hopper arrangement in which the apparatus according to the invention may be used. A chute 10 is provided for directing a flow of generally nonmagnetic granular or powdered material containing a small percentage of magnetically permeable material, such as might appear in recovered plastic sweepings, from machinery wear, and the like, into hopper 13 which includes a conical discharge head portion 12 having an outlet aperture 13 for discharging the granular material from the hopper 11. When the apparatus shown in FIG. 2 is used for drying granular plastic material, for example, polyolefines, styrenes, nylons, acrylics, cellulosics, polycarbonates, vinyls and acetals, the aperture 13 of hopper 11 may be provided with suitable extensions to pass the flow directly into a plastic extruder or molder. In addition, such an apparatus may have material flow controls as desired.

Means are provided for introducing heated air into the hopper 11 for drying the flow of granular material. A blower 15 provides the air to be heated to heater 16. The heated air is passed to hopper 11 by way of heated air conduits 17, suitably dimensioned as by elbows 18, 19 and 20 for introduction into the hopper. The blower may be of a conventional centrifugal blower-type such as may be powered by a motor and belt arrangement where the motor is of the order of 1 to 5 horsepower. In a practical embodiment, air was supplied to the heater at a pressure of 1 to 2 pounds per square inch. Heater 16 may be of the conventional type, such as a gas-fired or electric resistance heater. Where desired, the air system may include a suitable filter means (not shown). In addition, more sophisticated controls may be provided such as thermostatic regulation and the like. Conduit 17 may be either fixed or flexible according to the needs of the installation.

When positioned in the hopper 11, apparatus 1 according to the invention comprises a generally vertical cylindrical member 21 for attachment to the elbow 20 of conduit 17 for receiving heated air into the drying area. In the embodiment shown, an L-shaped aperture 22 is provided in one end of the member 21 for receiving a securing lug 23 on elbow 20. It should be understood that other means known to the art, such as welding, securing with fasteners, or slip-fitting, may be used.

The lower end of the member 21 terminates in a transition piece 24 which is secured to a dispersing member 25 to divert the heated air to the desired locations. Deflector member 26, shown in FIGS. 3-5, may be secured to member 25 to act as a baffle to provide adequate and even distribution of the heated air. The length of member 26 may vary in accordance with the needs of a particular installation. As may be understood, heated air from blower 15 and heater 16 passes through conduit 17, member 21, and transition piece 24, and is dispersed to the desired areas by dispersing member 25 and deflector member 26.

The invention contains means for dispersing the flow of granular material into a plurality of flow paths to aid the drying process. The flow dispersing means include a plurality of horizontally disposed inverted, generally V-shaped heated air diverter members 27 in a fixed, generally parallel-spaced relationship to form a flow grate. While one of the attributes of the apparatus 1 is its flexibility, both in length and width, which provides an attendant flexibility for the types of hopper installations in which the invention may be used, it is preferred that the dispersing member 25 interconnect with each of the diverter members 27 to provide a thermal network which may envelop the flow paths for the material. As illustrated in FIGS. 3 and 5, it is also preferred that the deflector member 26 extend to near the midpoint of the furthest diverter member 27 for a preferred heated air distribution.

The thermal network can best be seen in FIG. 5 where the dispersing member 25 interconnects with each of the diverter members 27 in the manner depicted generally at typical intersections 28 and 29. Intersection 29, it may be understood, is the intersection of the dispersing member 25 with the most remote diverter member 27 to provide adequate dispersion of the heated air to all portions of the gratelike dispersion head.

The spaces 30 between diverter members 27 provide a plurality of flow paths within the hopper 11 so that the material passing through the hopper may pass through the spaces provided between the diverter members 27.

Magnetic means, shown generally as permanent magnets at 33, for removing magnetically permeable material from the flow, are located in spaced relationship to each of the plurality of flow paths 30. Permanent magnets 33 are shown in a generally cylindrical configuration, although other forms of highly coercive permanent magnets may be used. The magnets 33 are placed in a generally parallel, spaced relationship with respect to each other and with respect to the passageways between diverter members 27. In the particular embodiment, as best seen in FIGS. 1-4, the magnets 33 are positioned in the flow path below the trailing edges of the inverted member 27. One convenient method of securing magnets 33 is by way of brackets 37 suitably secured, such as by welding, to each of the diverter members 27.

It has been found desirable, when placing the permanent magnets in the arrangement, to position like poles adjacent one another in adjacent magnet members 33 as best seen in FIG. 5. In this manner the magnetic force of repulsion between the like poles, such as a north magnetic pole adjacent to a north magnetic pole, is utilized to avoid bridging effects caused by the magnetically permeable materials segregated from the granular materials as they would attempt to span the gap between the magnetic members 33 if unlike magnetic poles were juxtaposed.

In its optimum form, permanent magnet members 33 may comprise a plurality of permanent magnet segments 34 and 35, such as are sold under the designation “Alnico,” in a spaced axial relationship within a stainless steel tubular member 36 provided with suitable end caps 38 and 39. For commercially available 2-inch cylindrical magnetic members 34 and 35, it has been found desirable to utilize approximately one-eighth or one-quarter inch spacing between adjacent axially spaced magnetic members 34 and 35. It has also been found preferable to juxtapose unlike magnetic poles of adjacent magnets 34 and 35 within the cylindrical member, such as is illustrated in FIG. 5.

For optimum utilization of the magnetic members, it has been found convenient to construct the apparatus 1 generally of stainless steel, although other nonmagnetic materials are equally satisfactory as long as corrosion and wear resistance factors are suitable.

As best seen in FIG. 2, the apparatus 1 may conveniently rest upon the sides of the discharge head portion 12 of hopper 11 to minimize installation costs.

In operation a flow of material enters the hopper 11 from chute 10 where it is separated into a plurality of streams, each passing through one of the flow paths 30. Heated air is provided to the apparatus 1 from the blower 15 and heater 16, via transition piece 22 and dispersing member 23 to be nearly uniformly distributed to the respective flow paths. The magnetic means 30 are of sufficient strength to segregate and retain the magnetically permeable materials from the respective flows of material.

While it would be apparent that the embodiment of the invention here disclosed is well calculated to fulfill the objects of the invention, it will be appreciated that the invention is susceptible to modification, variation and change without departing from the proper scope or fair meaning of the appended claims.