Abstract:
An infeed device provides a configuration that improves the flow of particulate material into a double wash deck dedusting apparatus. The infeed device is formed with a circular inlet opening, an oval-shaped discharge opening and step sides interconnecting the inlet and discharge openings to prevent bridging in particulate material being fed through the infeed device onto the wash decks. The infeed device can be formed as a separate member that can be inserted into the infeed opening of existing dedusters. The oval-shaped discharge opening is substantially smaller transversely than the diameter of the inlet opening, but has a longitudinal length that is equal to the diameter of the inlet opening and equal to the longitudinal length of the wash decks. The joinder of the wash decks is blunted to eliminate a divider edge on which plastic streamers can hang up while being fed to the wash decks.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates generally to an apparatus for the cleaning and handling of particulate materials, such as plastic pellets, grains, glass, and the like, and, particularly, to an infeed device for directing the particulate material onto the wash decks of the dedusting apparatus. 
       BACKGROUND OF THE INVENTION 
       [0002]    It is well known, particularly in the field of transporting and using particulate materials, commonly powders, granules, pellets, and the like, that it is important to keep product particles as free as possible of contaminants. Particulates are usually transported within a facility where they are to be mixed, packaged or used in a pressurized tubular system that in reality produces a stream of material that behaves somewhat like a fluid. As these materials move through the pipes, considerable friction is generated not only among the particles themselves, but also between the tube walls and the particles in the stream. In turn, this friction results in the development of particle dust, broken particles, fluff, streamers (ribbon-like elements that can “grow” into quite long and tangled), glass fibers in glass filled products, that can impede the flow of materials or even totally block the flow. The characteristics of such a transport system are quite well known, as is the importance and value of keeping product particles as free as possible of contaminants. 
         [0003]    The term “contaminant” as used herein includes a broad range of foreign material and includes foreign material as well as broken particles or streamers of the product being transported. The generation of contaminants, also referred to as dust, can be from a large number of sources, including, in the way of examples, the creation of dust particles during the processing of plastic pellets in which the larger particles are segregated to be re-ground; organic matter in food grains, such as shells and hulls; the creation of dust in the formation of iron ore pellets; and, as noted previously, the mere conveyance of the pellets in pipes and other mechanical conveying and handling systems. Using plastics as an example, such foreign material could have a detrimental effect on the finished product. Specifically, foreign material different in composition from the primary material, such as dust, and non uniform material of the primary product, such as streamers, would not necessarily have the same melting temperatures as the primary product and would cause flaws when the plastics material is melted and molded. 
         [0004]    Considering product quality, and focusing on moldable plastics as a primary example, foreign material different in composition from the primary material, such as dust, non-uniform material of the primary product, fluff, and streamers, does not necessarily have the same melting temperatures as the primary product and causes flaws when the material is melted and molded. These flaws result in finished products that are not uniform in color, may contain bubbles, and often appear to be blemished or stained, and are, therefore, unsellable. It is important to note that since these same non-uniform materials often do not melt at the same temperature as the primary product, the unmelted contaminants cause friction and premature wear to the molding machines, resulting in downtime, lost production, reduced productivity, increased maintenance and thus increased overall production costs. 
         [0005]    Since dust and other contaminants are generated mostly by the transport system, it is of primary importance to not only provide apparatus for thoroughly cleaning the particles, but to do so as close to the point of use of the particles as possible so as to avoid the generation of contaminants through additional transport. Accordingly, compact dedusters have been used for many years to clean materials in this application, capable of handling smaller volumes of product, yet also capable of thoroughly cleaning the product. The compact dedusters permit the installation of the deduster immediately before final use of the products, such as being installed directly on top of molding machines or extruders, or on top of silos, as well as under silos, rather than at an earlier stage after which re-contamination can occur before the products are utilized. Of course, the dedusters can be installed as a free standing unit, as well. 
         [0006]    Dedusters used to clean contaminants from particulate material can be found in U.S. Pat. No. 5,035,331, granted to Jerome I. Paulson on Jul. 30, 1991, in which air is blown upwardly through wash decks over which a flow of contaminated particulate material is passed so that the flow of air up through the wash decks removes the contaminants from the material flow. A magnetic field is provided by the deduster so that the particulate material flow passes through the magnetic field to neutralize the static charge on the particulates and facilitate the removal of the contaminants from the material. The flow of contaminant laden air is discharged from the deduster, while the cleaned particulate material is passed on to the manufacturing process. 
         [0007]    A compact dedusting apparatus is disclosed in U.S. Pat. No. 6,595,369, granted on Jul. 22, 2003, to Jerome I. Paulson. Like the larger dedusting apparatus depicted in U.S. Pat. No. 5,035,331, the follow of particulate material is cleansed of contaminates that have had the static charged attracting the contaminates to the particulates neutralized. The cleaning process utilizes a flow of air passing through the stream of particulate material passing over wash decks. The contaminate-laden air is discharged through the top of the dedusting apparatus, while the cleaned particulate material is discharged from the bottom of the deduster. 
         [0008]    These compact dedusters are provided with a single wash deck bathed in a magnetic flux field to provide dual action cleaning that fluidizes the flow of particles over the wash deck and uses a counter current flow to dislodge dust particles from the product for discharge from the apparatus. The magnetic flux field extends on opposing sides of the magnetic flux field generator, as well as above and below the magnet. Accordingly, a single wash deck is utilizing only a quarter of the magnetic flux filed that is generated. Furthermore, a single wash deck is limited in capacity. A double wash deck configuration is known from the Pelletron Max Series dedusters, wherein back to back wash decks are provided with a lower dust air outlet having a deflector panel to minimize the inadvertent discharge of cleaned particles with the dust-laden air being discharged from the lower air outlets. 
         [0009]    Dividing the flow of particulate material evenly over the oppositely directed double wash decks was enhanced by the use of a splitter that provided an edge extending into the infeed opening of the dedusting apparatus to split the inflowing particulate material into two oppositely directed streams. When the particulate material being fed into the dedusting apparatus had a lot of streamers, which are long strings of improperly formed particulate pellets, particularly found in plastic pellets, or in re-ground or soft plastic pellets, the streamers would hang up on the edge of the splitter, resulting in uneven feeding of material between the two wash decks and sometimes a plugging of the infeed area. Furthermore, the prior art infeed mechanism would often suffer from an uneven, or even on-sided material flow due to the operation of a rotary valve which is typically used to meter the flow of particulate material into the dedusting apparatus. 
         [0010]    Accordingly, it would be desirable to provide an infeed device that would not be subject to uneven flow characteristics or result in plastic streamers hanging up and not passing through the dedusting apparatus. 
       SUMMARY OF THE INVENTION 
       [0011]    It is an object of the invention to overcome the disadvantages of the prior art by providing an infeed device for use in compact dedusting apparatus that have a double wash deck configuration. 
         [0012]    It is another object of this invention to provide an effective infeed device that establishes an even flow divided between the opposing wash decks. 
         [0013]    It is still another object of this invention to provide an infeed device that will not engage plastic streamers in the particulate material flow into the dedusting apparatus. 
         [0014]    It is an advantage of this invention that the infeed device provides an even flow through the infeed device onto the wash decks. 
         [0015]    It is a feature of this invention that the infeed device is formed with a reduced opening area at the discharge opening compared to the inlet opening. 
         [0016]    It is another advantage of this invention that the infeed device funnels the particulate material into an oval-shaped opening to provide a constant flow onto the wash decks. 
         [0017]    It is another feature of this invention that the configuration of the infeed device transitions the circular inlet opening into an oval shaped discharge opening to direct the flow of particulate material onto the wash decks. 
         [0018]    It is still another advantage of this invention that the oval-shaped discharge opening is centrally positioned over the joinder of the opposing wash decks. 
         [0019]    It is yet another feature of this invention that the joinder of the wash decks is blunted so as to not present an edge on which streamers can engage and hang up. 
         [0020]    It is still another feature of this invention that the longitudinal length of the oval-shaped discharge opening of the infeed device is equal to the diameter of the inlet opening. 
         [0021]    It is a further feature of this invention that the transverse width of the oval-shaped discharge opening of the infeed device is substantially smaller than the diameter of the inlet opening. 
         [0022]    It is yet another advantage of this invention that infeed device distributes the incoming particulate material evenly to the entire wash deck area. 
         [0023]    It is still a further feature of this invention that the infeed device can be formed as a separate insert member that can be placed in existing deduster infeed openings to convert the infeed configuration of existing dedusters. 
         [0024]    It is a further advantage of this invention that the wide discharge opening of the infeed device allows the flow of regrind, soft pellets and particulate material with streamers to be fed onto the deduster wash decks without clogging. 
         [0025]    It is still a further feature of this invention that the infeed device is formed with steep sides extending between the inlet opening and the discharge opening to prevent the particulate material being fed into the dedusting apparatus from bridging. 
         [0026]    It is a further object of this invention to provide an infeed device for use in a double wash deck dedusting apparatus, which is durable in construction, inexpensive of manufacture, carefree of maintenance, facile in assemblage, and simple and effective in use. 
         [0027]    These and other objects, features and advantages are accomplished according to the instant invention by providing an infeed device to improve the flow of particulate material into a double wash deck dedusting apparatus. The infeed device is formed with a circular inlet opening, an oval-shaped discharge opening and step sides interconnecting the inlet and discharge openings to prevent bridging in particulate material being fed through the infeed device onto the wash decks. The infeed device can be formed as a separate member that can be inserted into the infeed opening of existing dedusters. The oval-shaped discharge opening is substantially smaller transversely than the diameter of the inlet opening, but has a longitudinal length that is equal to the diameter of the inlet opening and equal to the longitudinal length of the wash decks. The joinder of the wash decks is blunted to eliminate a divider edge on which plastic streamers can hang up while being fed to the wash decks. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0028]    The advantages of this invention will become apparent upon consideration of the following detailed disclosure of the invention, especially when taken in conjunction with the accompanying drawings wherein: 
           [0029]      FIG. 1  is a front elevational view of a compact dedusting apparatus incorporating the principles of the instant invention, the infeed device being shown in dashed lines as a separate member that can be placed into a standard infeed opening of the dedusting apparatus; 
           [0030]      FIG. 2  is a side elevational view of the compact dedusting apparatus depicted in  FIG. 1 ; 
           [0031]      FIG. 3  is a top plan view of the compact dedusting apparatus depicted in  FIG. 1 ; 
           [0032]      FIG. 4  is an enlarged partial front elevational view of the infeed area of the compact dedusting apparatus showing the relationship between the infeed device and the double wash deck configuration; 
           [0033]      FIG. 5  is an enlarged top plan view of the infeed device; 
           [0034]      FIG. 6  is an enlarged front elevational view of the infeed device shown in  FIG. 5 ; and 
           [0035]      FIG. 7  is an enlarged side elevational view of the infeed device shown in  FIG. 5 . 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0036]    The dedusting apparatus is known in the art. A description of the structure and operation of a dedusting apparatus and a compact dedusting apparatus can be found in U.S. Pat. No. 5,035,331 and in U.S. Pat. No. 6,595,369, both of which were issued to Jerome I. Paulson, the contents of each of these patents being incorporated herein by reference. Typical particulate material to be cleaned by the dedusting apparatus  10  is plastic pellets that are to be passed into an injection molding machine to form plastic components. Examples of plastic particulate material that can be cleaned of contaminate material by the dedusting apparatus  10  are polyester, acrylic, high density polyethylene, polypropylene, nylon, polycarbonates, styrene, and low density polyethylene. Other types of particulate material that can be cleaned in the dedusting apparatus  10  include glass particles and grain. 
         [0037]    Referring to  FIGS. 1-3 , the dedusting apparatus  10  is connected to a vertical portion of a fluent material handling system (not shown) such that the particulate material is fed into a product inlet port  30  located at the top of an airtight casing  11 . The casing  11  has two subcomponents, a main housing  15  in which the wash decks apparatus  50 , as described below, is mounted, and an air flow passageway  16  primarily located behind the main housing  15 . The product inlet port  30  is in flow communication with the main housing  15  to direct product particulates onto the first wash deck  52  for cleaning. A magnetic coil  31  generating a flux field is mounted at the inlet port  30  so that the flow of particulate material into the housing  15  to be cleaned is subjected to the magnetic flux field to neutralize the static charges on the particulate pellets, thus making the separation of the contaminates from the pellets easier to accomplish. Air is fed into the casing  11  through a clean air inlet port  20  located in the lower part of the back of the casing  11 . As is described in greater detail in co-pending and co-owned U.S. patent application Ser. No. 11/454,437, the contents of which are incorporated herein by reference, the air is distributed through a clean air plenum  18  via internal passages to a first inlet opening  22  below the first wash decks  52  and to a second inlet opening  24  below the second wash decks  55 . 
         [0038]    The casing  11  is formed with a back panel  12 , in which the clean air inlet port  20  and the dusty air discharge port  25  are located, and integral side, top and bottom panels that form a generally rectangular configuration. A removable front door  13  is connected to the remainder of the casing  11  by fasteners  13   a  to permit access into the wash deck apparatus  50  for service and maintenance thereof. An interior panel  14  oriented parallel to the back panel  12  and the front door  14  divides the casing  11  into a main housing  15  situated between the interior panel  14  and the front door  13  and an air flow passageway  16  situated between the back panel  12  and the interior panel  14 . A separator panel  17  divides the air flow passageway into a lower clean air plenum  18  and an upper dusty air plenum  19 , each of which being in flow communication with the respective clean air port  20  and the dusty air port  25 . 
         [0039]    The configuration of the wash deck apparatus  50  is in a double set, oriented back-to-back such that the first wash decks  52  are angled downwardly at an incline of approximately 30 degrees from the horizontal in opposing transverse directions. The second wash decks  55  are positioned beneath the first wash decks  52  so as to receive the flow of product particles therefrom and convey the product over an inclined surface that is also oriented at about a 30 degree incline relative to the horizontal. The first wash decks  52  are formed in a central diamond-shaped assembly that includes a lower deck member  54  associated with each of the first wash decks  52 . The lower deck members  54  help define an air flow path that directs air transversely outwardly into Venturi zones  35  through which air is directed in a counter current flow to aggressively remove dust particles from the product. 
         [0040]    Referring now to  FIGS. 1-7 , to improve the flow of particulate material through the inlet opening  30  onto the first wash decks  52 , an inlet device  40  funnels the particulate material from the circular inlet opening  30  into an oval-shaped discharged opening  45  having rounded ends  47  and linear longitudinal sides  46 , which is centered over the joinder of the two opposing first wash decks  52 . The inlet device  40  can be formed as a separate, free-standing component that is placed into the conventional inlet structure  30  of the deduster  10 , or integrally formed as part of the inlet structure  30 . Further description of the inlet device  40  will be as a separate, free-standing component, which is the embodiment shown in the drawings. 
         [0041]    The inlet device  40  is formed with a circular flange  41  that rests on top of the flange formed at the inlet opening structure  30  of the deduster  10 . One skilled in the art will recognize that the flange  41  and the flange of the inlet structure  30  would be the same component if the inlet device configuration  40  were integrally formed in the deduster  10 . The circular flange  10  encircles the inlet opening  42  for the inlet device  40  through which the particulate material would pass to the wash deck apparatus  50 . From the inlet opening  42 , the inlet device is formed with steep side walls  44  that are directed inwardly at the sides to form the oval-shaped discharge opening  45 . Accordingly, the discharge opening  45  has a longitudinal length that is substantially equal to the diameter of the inlet opening  42 , but has a transverse width dimension that is substantially smaller than the diameter of the inlet opening  42 . 
         [0042]    This structural configuration forms a funnel structure that concentrates the flow of particulate material onto the first wash decks  52  at the joinder thereof. The steep side walls  44  are oriented from about a 75° vertical angle at the center of the longitudinal sides  44  to a 90° vertical angle at the rounded ends to prevent bridging of the particulate material being converged from the larger circular inlet opening  42  to the smaller oval-shaped discharge opening  45 . One skilled in the art will recognize that the vertical angle of the side walls will depend on the relative sizes of the diameter of the inlet opening and the transverse width of the discharge opening, as well as the vertical depth of the inlet device between the inlet and discharge openings, but should preferably be greater than about 60° at the center of the discharge opening  45  to prevent bridging of the particulate material. 
         [0043]    To prevent the first wash decks  52  from having a sharp edge that would present structure on which streamers would hang up when fed through the inlet structure  30 , the joinder of the two opposing first wash decks  52  is preferably truncated to present a substantially flat landing  49  aligned with the center of the oval-shaped discharge opening  45 . With the use of the inlet device  40 , the deduster  10  does not utilize a splitter, as is described in the aforementioned U.S. patent application Ser. No. 11/454,437, thus further eliminating an edge on which streamers in the flow of particulate material could engage and potentially clog the inlet opening  30 . 
         [0044]    The inlet device  40  thus presents a discharge opening  45  for the passage of particulate material onto the wash deck apparatus  50  that has a longitudinal length dimension that is substantially identical to the longitudinal length of the first wash decks  52 , but has a transverse width that focuses the particulate material discharged onto the wash deck apparatus  50  evenly onto the first wash decks  52 . The linear sides  46  of the discharge opening  45  direct the flow of material into a curtain-like pattern that falls uniformly along the first wash decks  52 , reducing the need for product deflectors as are shown and described in the aforementioned U.S. patent application Ser. No. 11/454,437. 
         [0045]    Product to be cleaned is introduced into the housing  15  through the product inlet opening  30  at the center of the top portion of the housing  15 . The magnetic coil  31  is positioned around the product inlet port  30  to introduce a magnetic flux field which covers the entire housing  15 . The second air wash deck  55  is supported by the housing  15  in a downwardly directed incline opposite to that of the first air wash deck  52 , though also oriented at a minimum angle of 30 degrees to the horizontal. In other words, the second wash decks  55  are angled from both opposing sides to direct a flow of product particles toward the center where the product discharge port  34  is located. Pressurized air is introduced into the second air wash deck  55  from the second inlet openings  24  in the interior panel  14  located beneath the second wash decks  55  to pass upwardly through the second air wash deck  55  similarly to that described above with respect to the first air wash deck  52  to clean any remaining contaminates from the flow of particulate product directed onto the second air wash deck  55 . 
         [0046]    The product particles moving off of the first wash deck  52  may have sufficient velocity, particularly due to the velocity boost generated by the ribbon of air passing through first wash decks  52 , that the product particles may impact a generally vertical deflector plate  36  defining the outboard sides of the Venturi zones  35 . Product deflected off of the deflector plates  36  are directed downwardly to the second air wash decks  55 . The product discharge port  34  is provided at the center of the housing  15  between the two second wash decks  55  to receive product from the second wash decks  55  for discharge from the housing  15 . 
         [0047]    Air entering through the second inlet opening  24  is also directed behind the deflector plates  36  for use in adjusting the air flow in the Venturi zones  35 . The air flow chamber  39  extends rearwardly into the clean air plenum  18  rearwardly of the interior panel  14  to deliver air above the second wash decks  55  and behind the deflector plates  36 . An adjustment mechanism  38  is connected to each respective deflector plate  36 , which is pivotally mounted so that the bottom of each deflector plate  36  is movable into the corresponding Venturi zone  35 , to permit a flow of air past the bottom of the deflector plates  36  into the Venturi zones  35 , thus increasing the air flow through the Venturi zones  35 . The air flow through the wash decks  52 ,  55  and through the Venturi zones  35  is directed upwardly toward the dusty air outlet openings  28 . 
         [0048]    In operation, the dedusting apparatus  10  receives a volume of contaminated particulate material to be cleaned which is introduced into the product inlet port  30 . The particulate material passes through the magnetic flux field generated by magnetic coil  31  to disrupt the static charge attraction causing the contaminants to adhere to the individual particles of the particulate material. Material flow control is important in order to cause particulate particles to disperse in such a way that air can flow freely through the product stream so as to lift contaminants upward away from the product. The flow of material through into the dedusting apparatus  10  is controlled by the inlet device  40  and divided into laterally opposing flow paths onto the first air wash decks  52 . 
         [0049]    The first air wash decks  52  separate small particles of 100 microns and less from the flow of particulate material thereon. The Venturi zones  35  (between the first air wash decks  52  and the deflector plates  36 ), when adjusted correctly, will remove larger contaminants, thereby providing a two stage separation of contaminants as large as 1/52 of an inch. The particulate material is then passed across the second air wash decks  55  with residual contaminates being separated at this time. Finally, the cleaned product drops to the bottom of the main housing  15  and is discharged out of the dedusting apparatus  10  through the product outlet port  34 . 
         [0050]    Because of the different characteristics of the various products that can be introduced into the apparatus  10  to be cleaned of dust particles, certain aspects of the apparatus are made adjustable, as is generally known in the art. For example, the deflector plates  36  forming the outboard sides of the respective Venturi zones  35  are preferably positionally adjustable so as to both change the physical dimensions of the Venturi zones  35 , which alone changes the velocity of the air flowing through the Venturi zones  35 , but also adds air flow past the deflector plates  36  into the Venturi zones  35 . Too much air and too great of a velocity for some products will increase the product carryover into the dusty air discharge openings. Under typical operating circumstances, the preferable pressure differential between the Venturi zones  35  and the dusty air discharge openings  28  is equal to about five inches of water. 
         [0051]    It will be understood that changes in the details, materials, steps and arrangements of parts, which have been described and illustrated to explain the nature of the invention will occur to and may be made by those skilled in the art upon a reading of this disclosure within the principles of the scope of the invention. The foregoing description illustrates the preferred embodiment of the invention; however, concepts, as based upon the description may be employed in other embodiments without departing from the scope of the invention. Accordingly, the following claims are intended to protect the invention broadly, as well as in the specific form shown.