Abstract:
A dedusting apparatus is formed with back-to-back wash decks sloped downwardly and outwardly from a central inlet opening through which contaminated particulate material in directed onto the wash decks. The wash decks terminate at discharge edges from which particulate material enters a Venturi zone outwardly from each wash deck. The housing for the dedusting apparatus includes a pair of laterally spaced outlet ports located below the respective Venturi zones for the collection of cleaned particulate material simultaneously with identical or different collection devices such that the discharge outlets are offset laterally from the central inlet opening. The discharge ends of the wash decks are supported by an angularly disposed support leg. The air manifold directs air into the apparatus through a central opening from which the air passes through openings in the two sloped wash decks and past the discharge edges of the wash decks to create the Venturi zones.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation-in-part of U.S. patent application Ser. No. 13/041,678, filed on Mar. 7, 2011, and claims domestic priority on U.S. Provisional Patent Application Ser. No. 61/319,251, filed Mar. 30, 2010, and on U.S. Provisional Patent Application Ser. No. 61/489,460, filed on May 24, 2011, the contents of which are incorporated herein by reference. 
    
    
     FIELD OF THE INVENTION 
     The invention disclosed in this application is directed generally to an apparatus for the cleaning and handling of particulate materials, such as plastic pellets, grains, glass, and the like, and particularly to the a dedusting apparatus that can be utilized with product feed conduits extending at an angle to vertical. 
     BACKGROUND OF THE INVENTION 
     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. 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. 
     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, including microdust, 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. Furthermore, streamers can impact the weighing scale and plug the dosing screws at bagging stations. 
     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. 
     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, before packaging and bagging, 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. 
     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. 
     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. 
     In U.S. Pat. No. 7,380,670, granted on Jun. 3, 2008, to Jerome I. Paulson, et al, and in U.S. Pat. No. 8,016,116, granted on Sep. 13, 2011, to Heinz Schneider, the dedusting apparatus includes a pair of oppositely directed wash decks receiving contaminated particulate material from a common infeed port. The infeed mechanism divides the material flow between the two opposing wash decks and directs the particulate material over a flow of air passing through the first wash decks, then through laterally spaced Venturi zones and onto inwardly directed secondary wash decks that direct the cleaned particulate material into a central discharge opening. Air flow to the primary and secondary wash decks is directed through a rearwardly located manifold that has a central primary opening and laterally spaced lower openings below the secondary wash decks. 
     These compact dedusters are provided with single and double (back-to-back) wash decks and are utilized with a vertically oriented conduit in which particulate material is conveyed to the manufacturing apparatus utilizing the particulate material. Accordingly, the product inlet opening at the top of the dedusting apparatus is in vertical alignment with the cleaned product outlet opening. The particulate material is introduced into the inlet opening and is metered onto a diagonally oriented primary wash deck through which air is blown from an air supply inlet to clean dust and debris from the particulate material flowing over the wash deck. In these dedusting devices, the particulate material is discharged off the lower end of the wash deck and falls through a Venturi zone in which air is moving upwardly to provide a vigorous cleaning action to the particulate material. The material falling through the Venturi zone is received on a secondary wash deck that is oriented oppositely of the primary wash deck to direct material back to the centrally aligned cleaned product outlet opening. 
     Further, with a single inlet and a single outlet, the conventional dedusting apparatus is limited in operation to being utilized to feed a single receiver of the cleaned particulate material passing through the dedusting apparatus. As is noted above, the discharge from the dedusting apparatus is typically used to load railroad cars or trucks, or to be received in a collection bag. With a single discharge outlet in the dedusting apparatus, the receiver can only be one of these conventional devices. 
     With increasing capacity of the dedusting apparatus, it would be advantageous to provide for multiple receivers of the cleaned particulate material from a single dedusting apparatus. With multiple discharge openings, two bagging stations could be filled simultaneously. 
     SUMMARY OF THE INVENTION 
     It is an object of this invention to overcome the disadvantages of the prior art by providing an apparatus for removing dust and debris from particulate material from which multiple discharge outlets can be used. 
     It is another object of this invention to provide a dedusting apparatus with multiple discharge ports. 
     It is an advantage of this invention that different disposal devices can be utilized to collect cleaned particulate material from a single dedusting apparatus. 
     It is a feature of this invention that the dedusting apparatus does not include a secondary wash deck. 
     It is another feature of this invention that the air manifold directs air underneath the primary wash deck to pass through openings in the wash deck and around the discharge edge of the wash deck to create a Venturi zone through which the particulate material must pass before being discharged from the dedusting apparatus. 
     It is another advantage of this invention that the discharge ports are offset relative to the inlet opening through which the contaminated particulate material passes into the dedusting apparatus. 
     It is still another feature of this invention that the dirty air discharge from the dedusting apparatus is located above the Venturi zone on both sides of the primary wash deck. 
     It is still another advantage of this invention that the collection of cleaned particulate material in bags is facilitated by having dual discharge outlets. 
     It is still another object of this invention to support each wash deck with a support member that angles inwardly from the discharge edge of the wash deck to the floor of the housing. 
     It is yet another feature of this invention that the support member is formed with slotted openings to direct a flow of air from the air manifold through the support member and into the Venturi zone. 
     It is a further feature of this invention that the smallest horizontal dimension for the Venturi zone is located at the discharge edge of the wash deck. 
     It is yet another advantage of this invention that the cleaning of dirt and debris from particulate material at the Venturi zone is improved by utilizing an angled support member for the wash deck. 
     It is still another object of this invention to provide a dual discharge outlet dedusting apparatus, which is durable in construction, inexpensive of manufacture, carefree of maintenance, facile in assemblage, and simple and effective in use. 
     These and other objects features and advantages are accomplished according to the instant invention by providing a dedusting apparatus formed with back-to-back wash decks sloped downwardly and outwardly from a central inlet opening through which contaminated particulate material in directed onto the wash decks. The wash decks terminate at discharge edges from which particulate material enters a Venturi zone outwardly from each wash deck. The housing for the dedusting apparatus includes a pair of laterally spaced outlet ports located below the respective Venturi zones for the collection of cleaned particulate material simultaneously with identical or different collection devices such that the discharge outlets are offset laterally from the central inlet opening. The discharge ends of the wash decks are supported by an angularly disposed support leg. The air manifold directs air into the apparatus through a central opening from which the air passes through openings in the two sloped wash decks and past the discharge edges of the wash decks to create the Venturi zones. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       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: 
         FIG. 1  is a schematic front perspective view of a dedusting apparatus incorporating the principles of the instant invention; 
         FIG. 2  is a schematic front elevational view of the dedusting apparatus shown in  FIG. 1 , the movement of the Venturi deflector members to control the air flow thought the Venturi zones being shown in phantom; 
         FIG. 3  is a top plan view of the dedusting apparatus shown in  FIG. 1 ; 
         FIG. 4  is a end elevational view of the dedusting apparatus shown in  FIG. 1 ; 
         FIG. 5  is a rear elevational view of the dedusting apparatus shown in  FIG. 1 ; 
         FIG. 6  is a bottom plan view of the dedusting apparatus shown in  FIG. 1 ; 
         FIG. 7  is a rear perspective view of the dedusting apparatus shown in  FIG. 1 ; 
         FIG. 8  is a perspective cross-sectional view of the dedusting apparatus taken along lines  8 - 8  of  FIG. 4 ; 
         FIG. 9  is a front cross-sectional view of the dedusting apparatus corresponding to the section depicted in  FIG. 8 ; and 
         FIG. 10  is cross-sectional view of the main housing taken along lines  10 - 10  in  FIG. 4  to show the clean air plenum. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The dedusting apparatus is known in the art. A general description of the structure and operation of a conventional dedusting apparatus and a conventional 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. 
     Referring to  FIGS. 1-9 , the dedusting apparatus  10 , incorporating the principles of the instant invention, defines a central product inlet port  13  that is typically 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  13  located at the transverse center at the top of a generally airtight main housing  11 . The main housing  11  has supports a pair of oppositely directed wash decks  20  that receive particulate material to be cleaned from the inlet port  13 , as will be described in greater detail below. The main housing also defines an air inlet passageway  15  having an air inlet port  16  in the rear wall  12  of the main housing  11 . As will be described in greater detail below, the introduction of an air flow through the air inlet port  16  will direct air through the wash decks to clean the particulate material. 
     The product inlet port  13  directs product particulates onto the wash decks  20  for cleaning. A magnetic coil  13   a  generates a magnetic flux field and is mounted at the inlet port  13  so that the flow of particulate material into the main housing  11  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, particularly microdust, from the pellets easier to accomplish. Air is fed into the housing  11  through the clean air inlet port  16  through the rear wall  12  to direct a flow of clean air into the housing  11 , as will be described in greater detail below. A portion of the clean air passing through the inlet opening  16  is directed upwardly through the wash decks  20 , while a remaining portion of the clean air flowing into the housing  11  is distributed to the Venturi zones  30 , as will be described in greater detail below. One skilled in the art will recognize that baffles (not shown) may have to be provided to accomplish the desired division of the clean air flow between the wash decks  20  and the Venturi zones  30 . 
     The wash decks  20  are supported by the housing  11  to present a downwardly sloping surface in opposite directions from the product inlet port  13  to the transversely spaced product outlet ports  14  over which the product to be cleaned, in the form of particulate particles, moves by gravity. An inlet deflector  22  is mounted to the housing  11  in a manner as to be slidable along the top surface of the housing  11  for directing the product particulates onto the wash deck  20 . The inlet deflector  22  includes a trailing leg  23  that is oriented generally parallel to the slope of the wash deck  20  to force the product particulates into a laminar flow downwardly over the surface of the wash deck  20  toward the outlet port  14 . The sliding movement of the inlet deflector  22  can be effected by manipulation of the adjustment pins  22   a  projecting through the housing  11  to allow adjustment of the depth of the laminar flow by positionally moving the inlet deflector  22  to the desired position. 
     The wash deck  20  is formed as a sloped tray having a top surface  24  in which are formed generally horizontal slots  25  and circular openings. The horizontal slots  25  are formed in conjunction with an upwardly extending deflector that presents a ramp to the product particulates moving downwardly over the top surface  24  of the wash deck  20 . The slot  25  is formed as the horizontal opening across the top surface  24  between the deflector and the top surface  24 , such that the air flowing through the slot  25  is directed by the deflector into the product in a generally horizontal direction, which is slightly upwardly with respect to the slope of the top surface  24  of the wash deck  20 . Air moving through the circular openings is directed generally perpendicularly to the sloped top surface  24  of the wash deck  20 . The net operative result is that the product particulates are subjected to a downward acceleration along the surface of the wash deck and to a turbulence generated by the movement of the particulates over the deflectors and by the substantially perpendicular air flow streams emanating from the circular openings and the horizontal slots  25 . Accordingly, dust and debris contaminates are released from the product particulates and are carried by the air flow to the dirty air exhaust port  19  at the top of the housing  11 . 
     The product particulates falling off of the lower end  21  of the respective wash decks  20  drop generally vertically toward the corresponding cleaned product outlet port  14  into a Venturi zone  30  through which air is blown upwardly through the falling product particulates to provide a vigorous finally cleaning. Air is directed into the Venturi zone  30  from beneath the wash deck  20  through louvers  29  in the support leg  28 , best seen in  FIG. 8 . Clean air can also be directed into the Venturi zones  30  through the bypass ducts  45 . As is best seen in  FIG. 10 , the main housing  11  is formed with a transverse, vertical central wall  17  on which the wash decks  20  are mounted. The clean air plenum or manifold  18  between the rear wall  12  and the central wall  17  is in flow communication with the clean air inlet opening  16   a  in the central wall  17  to direct a flow of air into the wash decks  20 . 
     The clean air plenum  18  is also in flow communication with the bypass ducts  45  which direct a flow of air forwardly around the main housing  11  and back into the main housing  11  in front of the central wall  17  to be directed behind and under the pivoted members  35  into the Venturi zones  30 . The amount of air moving through the bypass ducts  45  is controlled by dampers  46  pivotally mounted in the bypass ducts  45  The size of the Venturi zones  30  and the amount of air flow directed into the Venturi zones  30  is controlled by a pivoted member  35  operatively connected to a position adjustment lever  36  projecting outside of the main housing  11 . The movement of the pivoted member  35  is depicted in phantom in  FIG. 2 . 
     The flow of air into the Venturi zone  30  from beneath the pivoted member  35  and through the louvers  29  presents a substantial cleaning action to the product particulates falling through the Venturi zone  30 , but not so vigorous as to lift the product particulates to the dirty air exhaust port  19 . If too much air is moving through the Venturi zone  30 , the pivoted member  35  should be retracted to both increase the effective dimensions of the Venturi zone  30  and to decrease the amount of air moving into the Venturi zone. If the front wall  40  of the housing  11  were constructed of a transparent or semi-transparent polycarbonate, as is depicted in the drawings, the operation of the wash deck assembly could be physically viewed by looking through the front wall  40  to see if product particulates were being carried over into the dirty air exhaust port  19 . 
     The support member  28  extending downwardly from the discharge edge  21  of the wash deck  20  is angled inwardly, as best seen in  FIGS. 2 and 9 , from the discharge edge  21  of the wash deck to engagement thereof with the housing  11 . This angled configuration of the support member  28  directs the air outwardly from the louvers  29  into the Venturi zone  30  through which the particulate material falls from the discharge edge  21  of the wash deck  20 . Thus, the direction of air flow from the louvers  29  passes at an angle to the vertical movement of the particulate material falling off of the wash decks  20  to provide an enhanced cleaning operation in the Venturi zone  30  which would have its narrowest horizontal dimension at the discharge edge  21 . 
     The air flow in which the dust and debris contaminates are entrained is discharged from the housing  11  through the dirty air exhaust port  19  located at the top of the housing  11  above the Venturi zone  30  and on opposite sides of the product inlet port  13 . Slidable plates  33  are mounted on the dirty air discharge passageway  19   a  to be positionally adjustable by sliding the respective plates  33  into or out of the dirty air discharge passageway  19   a , which thus defines the throat opening of the dirty air exhaust passageway  19   a.    
     The transparent front wall  40  of the housing  11  is removable from the housing  11  by releasing fasteners  41  from the frame supports  43  connecting the frame  42  of the front wall  40  to the housing  11 . Alternatively, the front wall  40  can be formed as a hinged door with a handle  44  to facilitate movement of the front door  40  when released from the frame  42 . With the removal of the front wall  40 , the interior components, including the wash deck  20 , the inlet deflector  22 , and the pivoted member  35 , can be removed from the housing  11  to facilitate cleaning of the interior of the housing  11  and the removed components  20 ,  22 ,  35 . 
     The slope of the wash deck  20  is calculated to optimize product flow and air wash of the product particulates passing over the top surface  24  of the wash deck  20 . The transversely spaced dual product outlet ports  14  are aligned with the ends of the corresponding wash decks  20  so that the cleaned particulate material can be packaged in two different manners. For example, separate collection bags (not shown) could be associated with each of the product outlet ports  14 , or used to supply two different production lines. The oppositely positioned product outlet ports  14  provide substantial flexibility in use. 
     In operation, the dedusting apparatus  10  is installed at an appropriate location in conjunction with the desired utilization of the product outlet ports  14 , and connected to a supply of particulate material through the product inlet port  13 . The product particulates pass through the product inlet port  13  and are oriented into a laminar flow over the oppositely oriented sloped wash decks  20  by inlet deflectors  22 , which are positionally adjustable relative to the wash deck  20  to define a desired product flow thickness over the wash deck  20 . 
     Clean air is received through a clean air inlet opening  16   a  and directed into the housing  11  beneath the wash decks  20  and a flow that passes through louvers  29  in the support legs  28  for the wash decks  20  to the Venturi zones  30 . The air flowing into the housing  11  beneath the wash decks  20  passes through slots  25  and openings formed in the wash decks  20 . The air passing through the slots  25  and openings in the wash decks  20  create turbulence in the product particulates moving along the top surface  24  of the respective wash decks  20 . Turbulence is enhanced by the upwardly projecting deflectors and the orientation of the horizontal slots  25  which accelerates the flow of the product particulates over the wash deck  20  and further creates turbulence. This movement of air through the wash decks  20  and through the flowing product particulates removes dust and debris contaminates from the product particulates, the static attraction forces having been neutralized by the magnetic flux field induced at the product inlet port  13  by the magnetic flux generator  13   a.    
     The cleaned product particulates are discharged off the lower end  21  of the wash decks  20  into corresponding Venturi zones  30  having an upwardly moving air flow coming from the louvers  29  in the wash deck support leg  28  and from the bypass ducts  45  which flows behind and then under the Venturi deflector members  35  to enter the Venturi zones. This upwardly moving air flow provides a vigorous cleaning action to the product particulates falling through the Venturi zones  30  with the air flow therefrom combining with the air flow passing through the wash decks  20  to the dirty air exhaust port  19  at the top of the housing  11 . The cleaned product particulates can fall through the respective product outlet ports  14  for packaging or for delivery to the manufacturing facility. The transparent front wall  40  of the housing  11  allows a visual inspection of the operation of the dedusting apparatus  10  to determine if adjustment to the inlet deflectors  22  or the Venturi deflector members  35 , through manipulation of the control lever  36  to move the pivoted Venturi deflector members  35 , is necessary. Furthermore, the removable front wall  40 , allows convenient access to the interior of the housing  11  to facilitate cleaning of the housing  11  and all of the removable components therein. 
     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.