Abstract:
An air material separator may be used to separate scrap from a conveying air flow while having a relatively low weight and short height so that the separator may be positioned within today&#39;s single-story manufacturing or processing facilities. The air material separator of the invention includes a generally cylindrical inlet chamber having a spiral wall that directs the inlet flow circumferentially and downwardly. An outlet chamber is positioned below the inlet chamber and includes a conical, perforated wall that allows the conveying air flow to escape through the perforated wall. The scrap carried by the conveying air flow cannot pass through the perforated wall and moves down and out an outlet at the bottom of the conical wall. The overall height of the device is substantially less than prior art air material separators.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority from U.S. provisional application Ser. No. 60/258,424, filed Dec. 27, 2000; the disclosures of which are incorporated herein by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Technical Field 
     The present invention generally relates to devices that separate solids from air and, more particularly, to a device that separates scrap from a transport air flow. Specifically, the invention relates to an air material separator or receiver that has compact dimensions and a low overall weight that allow it to be positioned inside a building instead of on the roof as in the prior art. 
     2. Background Information 
     Various systems use a pneumatic conveying system to remove scrap from a processing area and to deliver the scrap to a waste container. In the context of this patent application, the terms scrap, trim, broke, edge trim, waste, and web shall be used interchangeably to reference items that are being transported by an air stream and then separated from the air stream. Each of these pneumatic conveying scrap systems uses an air material separator to separate the scrap from the air stream. The scrap may be paper, plastic, film, finished products, cellulose casings, meat packing casings, packing materials, fiberglass, tissue, fabric, or metal foils. The scrap may be supplied in individual pieces or in continuous lengths. 
     Prior art air material separators have been located outside or on the roof of a building because their heights typically prevent the device from being located inside the building. The roof location was acceptable in the past because buildings were constructed in a manner to have a roof that could support the weight of the air material separator. Many newly-constructed manufacturing or processing facilities are single story structures having a relatively low, light-weight roof that typically cannot support the weight of an air material separator. The art thus desires an air material separator that can be placed inside buildings having low roofs and roofs that cannot support heavy equipment. Ideally, the air material separator must be light enough to be suspended from the roof joists. 
     A cyclone is an air material separator used in past separation applications. Cyclones are typically relatively tall so that the cyclonic action inside the cyclone has enough time to force the materials to the outside of the separator before the air flow is turned sharply upward to exit the device. The height of most cyclones prevent them from being used inside building structures. For example, one type of 9,000 CFM cyclone is about 210 inches tall (17½ feet). An existing 14,500 CFM cyclone is about 254 inches tall (over 21 feet). An existing 21,500 CFM cyclone is about 303 inches tall (25 feet tall). 
     Other types of air material separators known in the art function by slowing the scrap-laden airflow to a velocity slow enough to cause the scrap to fall out of the airflow. These devices may also redirect the flow as it is being slowed to encourage the scrap to fall out of the flow. These types of devices typically use an expansion chamber to slow the velocity of the flow. 
     BRIEF SUMMARY OF THE INVENTION 
     The invention provides an air material separator that may be used to separate scrap from a conveying airflow while having a relatively low weight and short height so that the separator may be positioned within today&#39;s single-story manufacturing or processing facilities. The air material separator of the invention includes a generally cylindrical inlet chamber having a spiral wall that directs the inlet flow circumferentially and downwardly. An outlet chamber is positioned below the inlet chamber and includes a conical, perforated wall that allows the conveying air flow to escape through the perforated wall. The scrap carried by the conveying air flow cannot pass through the perforated wall and moves down and out an outlet at the bottom of the conical wall. The overall height of the device is substantially less than prior art air material separators. 
     In one embodiment of the invention, a shroud may be positioned about the conical wall to control the removal of the air flow from the air material separator to contain any expelled particles or dust. 
     Another objective of the invention is to provide an air material separator wherein the air does not have to be slowed to a low velocity to separate the scrap from the air. 
    
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
     The preferred embodiment of the invention, illustrative of the best mode in which applicant has contemplated applying the principles of the invention, are set forth in the following description and are shown in the drawings and are particularly and distinctly pointed out and set forth in the appended claims. 
     FIG. 1 is a schematic view of a typical system using the air material separator of the present invention. 
     FIG. 2 is a side elevational view of the air material separator with a shroud. 
     FIG. 3 is a top plan view of the air material separator with a shroud. 
     FIG. 4 is a front elevational view of the air material separator with a portion of the shroud broken away to show the perforated cone. 
     FIG. 5 is a perspective view of the air material separator (without the shroud) with the outer wall broken away so that the spiral top wall may be seen. 
     FIG. 6 is a side elevational view of the air material separator with the shroud showing air and scrap moving through the device with the air and scrap being indicated by different arrows. 
     FIG. 7 is a view similar to FIG. 5 showing air and scrap moving through the device with the air and scrap being represented by different arrows. 
     FIG. 8 is a graph showing the velocity of air exiting the outlet chamber at various points about a 5000 CFM air material separator. 
     FIG. 9 is a graph showing the velocity of air exiting the outlet chamber at various points about a 7500 CFM air material separator. 
     FIG. 10 is a graph showing the velocity of air exiting the outlet chamber at various points about a 10,000 CFM air material separator. 
    
    
     Similar numbers refer to similar parts throughout the specification. 
     DETAILED DESCRIPTION OF THE INVENTION 
     The air material separator of the present invention is indicated generally by the numeral  10  in the accompanying drawings. FIG. 1 depicts an exemplary system using air material separator  10 . The system is located inside a building  12  having at least one machine  14  that creates scrap to be removed by a conveying air flow. In the system depicted in FIG. 1, three machines  14  are connected to a single air material separator  10  that separates the scrap from the conveying air flow. The conveying air flow is created by connecting a blower  18  to a device that creates a vacuum flow such as a venturi. A device  16  such as a venturi tube creates the conveying air flow for each machine  14  that carries the scrap to air material separator  10 . In other embodiments of the invention, the scrap may be pulled or pushed directly through a conveying fan without the need for using a venturi tube. Air material separator  10  slows the conveying air flow, separates the scrap from the flow, and drops the scrap out of the outlet of the material separator  10  into a waste container  20 . As shown, waste container  20  may be located outside of building  12 . In other embodiments, waste container  20  and air material separator  10  may be located outside of the room that houses machines  14 . This location allows machines  14  to be kept as sanitary as possible. Such an arrangement is desired in food scrap processing systems. 
     Air material separator  10  generally defines an inlet chamber  22  and an outlet chamber  24  that are in fluid communication with each other. Inlet chamber  22  includes an inlet  30  that initially receives the scrap-laden air flow. Inlet  30  is connected to a generally cylindrical outer sidewall  32  having a substantially circular upper edge  34  and a substantially circular lower edge  36 . In another embodiment of the invention, upper edge  34  may be oval or elliptical depending on the shape of outer sidewall  32 . A spiral wall  40  extends from upper edge  34  of inlet  30  to lower edge  36  in a spiral manner as shown in FIG.  5 . An inner sidewall  42  is connected to the inner edge of spiral wall  40 . Inner sidewall  42  is also substantially cylindrical in the preferred embodiment of the invention and is disposed substantially concentric with sidewall  32 . An inlet flow path is defined between sidewalls  32 , 42  and spiral wall  40 . 
     The bottom of inlet chamber  22  is open and exposed to outlet chamber  24 . A top wall  44  is connected to upper edge  34  and may or may not close off the inner portion of inner sidewall  42 . In the embodiment of the invention depicted in the drawings, top wall  44  caps the space inside of inner sidewall  42 . In other embodiments, the space inside inner sidewall  42  is in communication with outlet chamber  24 . When the end of inner sidewall  42  is not capped off, the opening will provide a visual indication of a scrap jam as pieces of scrap and some conveying air will exhaust through the opening. 
     Inlet  30  includes an outer sidewall  50 , an inner sidewall  52 , a top wall  54 , and a bottom wall  56 . Outer sidewall  50  is preferably tangentially disposed with respect to outer sidewall  32  of inlet chamber  22 . Inner sidewall  52  is substantially parallel to outer sidewall  50 . Top and bottom walls  54  and  56  are also substantially parallel. Inlet  30  further includes a face frame  58  that connects with the supply line  60  (schematically shown in FIG.  1 ). Face frame  58  is preferably angled with respect to the longitudinal centerline  60  of inlet  30  as shown by reference angle  62  (line  64  being perpendicular to face plate  58 ). Angle  62  is preferably 15 degrees but may be disposed at any angle between zero and 45 degrees. The angled orientation of face plate  58  orients the incoming duct at an angle with respect to centerline  60  and forces at least a portion of the scrap-laden airflow to wipe against outer sidewall  50  and outer sidewall  32 . In other embodiments of the invention, face plate  58  is perpendicular to centerline  60 . An access panel  66  may be provided in outer sidewall  50 . An inlet opening  68  provides fluid communication between inlet  30  and inlet chamber  22 . 
     Spiral wall  40  preferably spirals downwardly from upper edge  34  to lower edge  36  over a 270 degree to a 360 degree arc. The arc may also be other lengths without departing from the concepts of the invention. Spiral wall  40  preferably starts extending downwardly immediately downstream of inlet opening  68 . Top wall  44  is parallel to top wall  54  of inlet  30  in the area of inlet chamber  22  immediately adjacent opening  68 . Spiral wall  40  then starts moving downwardly in a tangential or angled manner. Spiral wall  40  then drops downwardly until it reaches lower edge  36 . Wall  40  may drop down at a varying or constant angle. Spiral wall  40  causes the scrap-laden flow to move downwardly as it moves around inlet chamber  22 . 
     The bottom of inlet chamber  22  is entirely open to outlet chamber  24  along the flow path. The scrap-laden airflow may thus drop down out of inlet chamber  22  into outlet chamber  24  at any time after entering inlet chamber  24 . 
     Outlet chamber  24  is defined by a perforated conical wall  70  having an upper edge  72  connected to lower edge  36  of sidewall  32 . Conical wall  70  also includes a cylindrical lower portion or edge  74  connected to a scrap outlet  76 . Conical wall  70  has an open area of 20 to 90 percent of its area. Wall  70  may be perforated with round, oval, diamond, slotted, square, hexagonal, or other shaped openings. Wall  70  may be fabricated from a variety of rigid materials and may be fabricated by placing a cloth material over a frame. Wall  70  may be angled (angle  84 ) between zero and 45 degrees from vertical. 
     Outlet chamber  24  separates the scrap from the conveying airflow without causing any down blast to exit chamber  24  through scrap outlet  76 . Conical wall  70  is configured to cause essentially all of the conveying airflow to pass through wall  70  and out of air outlet  78 . A shroud  80  surrounds wall  70  to contain the conveying airflow and to direct it to air outlet  78 . Shroud  80  thus allows the airflow to be moved outside building  12  as depicted in FIG.  1 . An access door  82  may be provided in shroud  80  to allow shroud  80  and the perforated  70  to be cleaned. 
     For the purpose of providing an example and to compare air material separator  10  of the present invention to prior art devices, the following exemplary embodiments are provided. A 4,600 CFM air material separator of the present invention weighs approximately 265 pounds and has an overall height of 39.86 inches. The overall diameter of the unit is 36.12 inches. A 9,000 CFM air material separator has an overall height of 53.87 inches. The device weighs 420 pounds and has an overall diameter of 48.12 inches. A 15,000 CFM air material separator weighs 600 pounds and has an overall height of 67.77 inches. The overall diameter is 16.12 inches. In a 22,000 CFM air material separator, the overall height is 81.64 inches with the weight being 810 pounds. The overall diameter is 72.12 inches. In each of these embodiments, conical wall  70  is angled 30 degrees inwardly from vertical as indicated by angle  84  depicted in FIG.  4 . The overall heights of these devices are substantially less than prior art devices having similar flow rates. The relatively small overall heights and diameters allow the devices to be installed inside buildings. A relatively low overall weights allow the units to be supported by roof joists. 
     The movement of air and material through separator  10  is depicted schematically in FIGS. 6 and 7 with the air being represented by arrows  90  and scrap being represented by arrows  92 . The scrap-laden air flow enters inlet  30  at an angle with respect to outer sidewall  50  as described above. This motion pushes some scrap toward outer sidewall  32  of inlet chamber  22 . Upon entering inlet chamber  22 , air  90  and scrap  92  immediately encounter spiral wall  40  and begin moving down into outlet chamber  24 . The circular nature of inlet chamber  22  and spiral wall  40  immediately force a large amount of air and material against conical wall  70  immediately adjacent the end of spiral wall  40  (FIGS.  8 - 10 ). The velocity of the air flow passing through wall  70  reaches its maximum at the top of wall  70  one sixth of its circumference from the inlet. The velocity remain high through ⅓ of the circumference and then drops back to zero. The velocity actually becomes negative (back flow) over the last portion of the circumference. The velocity of the air passing through wall  70  is graphically depicted in FIGS. 8-10 for different separator configurations. For instance, in a 5,000 CFM unit, the average velocity of air  90  passing through wall  70  increases to approximately 380 feet per minute and remains at approximately this value about a third of the way around wall  70  before the velocity of air  90  passing through wall  70  begins to drop. Air material separator  10  functions differently than prior art devices because the air velocity does not have to be drastically decreased in order to drop the scrap out of the air flow. In the prior art devices, the air velocity was significantly slowed by expanding an air flow in order to drop scrap out of a device. In this device, the air speed remains high as the scrap is removed. 
     As air  90  passes through conical wall  70 , scrap  92  drops down along conical wall  70  with a wiping action or falls through outlet chamber  24  until exiting outlet chamber  24  through scrap outlet  76 . Essentially no air  90  passes through scrap outlet  76 . When the top of inner wall  42  is open, very little air  90  moves up through wall  42 . 
     Outlet chamber  24  resists clogging because air  90  and additional scrap  92  are constantly pushing down through outlet chamber  24 . 
     In the foregoing description, certain terms have been used for brevity, clearness, and understanding. No unnecessary limitations are to be implied therefrom beyond the requirement of the prior art because such terms are used for descriptive purposes and are intended to be broadly construed. 
     Moreover, the description and illustration of the invention is an example and the invention is not limited to the exact details shown or described.