Abstract:
A cross-flow air separation system comprises a conveyor configured to project material out over an end of the conveyor generally along a trajectory path into a far receiving bin. An optical sensing system is configured to identify particular objects in the projected material. A first air ejection system is configured to generate a first airstream that ejects the identified objects from the trajectory path into a second near receiving bin. A second cross air current system is configured to generate a second airstream that reduces air resistance for the materials projected along the trajectory path. The second airstream reduces certain aeronautic phenomena that would cause some of the projected materials to unintentionally fall into the wrong receiving bin, thus creating a higher purity/less contaminated materiel stream into the near bin.

Description:
BACKGROUND 
       [0001]    An optical sensor is used to identify particular materials carried on a conveyor belt. The material is launched off the end of the conveyor and travels along a trajectory path into a far bin. Particular objects identified by the optical sensor are knocked out of their normal trajectory into a different near bin via a blast of air from a high pressure air nozzle. 
       SUMMARY 
       [0002]    A cross-flow air separation system comprises a conveyor configured to project material out over an end of the conveyor generally along a trajectory path into a far receiving bin. An optical sensing system is configured to identify particular objects in the projected material. The primary air ejection system, which operates perpendicular to the material flow, is configured to eject identified objects from the trajectory path into the near receiving bin. A second cross air current system is configured to generate a second airstream parallel to the material flow that reduces air resistance for the materials projected along the trajectory path. The second airstream reduces certain aeronautic phenomena that would cause some of the projected materials to unintentionally fall into the wrong receiving bin. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0003]      FIG. 1  is a side view of an optical air separation system used for separating plastic containers from other objects in a material stream. 
           [0004]      FIG. 2  shows some of the problems associated with the optical air separation system shown in  FIG. 1 . 
           [0005]      FIG. 3  is an isolated side view of a cross flow air separation system. 
           [0006]      FIG. 4  is a more detailed side view of the cross flow air separation system shown in  FIG. 3 . 
           [0007]      FIG. 5  is another side view showing how the cross flow air separation system reduces air resistance and reduces collision friction for projected materials. 
           [0008]      FIG. 6  shows a pneumatic transport system used in combination with the cross flow air separation system. 
           [0009]      FIG. 7  shows another embodiment of the pneumatic transport system that uses a venturi system to compensate for downward air pressure. 
       
    
    
     DETAILED DESCRIPTION 
       [0010]      FIG. 1  shows a schematic diagram of an optical air separation system  12 . A conveyor  24  carries different materials  26  that, in one example, may comprise Municipal Solid Waste (MSW) or may comprise primarily recyclable materials  26  referred to generally as a single stream. The single stream may include plastic, aluminum, steel, and glass containers and objects and may also include paper and Old Corrugated Cardboard (OCC). The MSW may contain these recyclable materials as well as other materials such as textiles, food waste, yard debris, wood, concrete, rocks, etc. Any MSW stream, single stream, or any other materials that may need to be separated are referred to generally below as a material stream. 
         [0011]    It may be desirable to separate certain objects or materials from the material stream  26 . For example, plastic, aluminum, steel, and glass objects may need to be separated from other recyclable or non-recyclable materials, such as paper, Old Corrugated Cardboard (OCC), textiles, food waste, yard debris, wood, concrete, rocks, etc. Further, the different plastic, aluminum, steel, and glass objects may all need to be separated. In one example described below, polyethylene terephthalate (PET) and/or high density polyethylene (HDPE) objects  28  are separated from other materials in material stream  26 . Of course, any variety of different objects  28  may need to be separated from the rest of material stream  26 . 
         [0012]    Theoretically based on gravity and conveyor speed, all the materials  26  would be projected from conveyor  24  at the same speed and travel generally along the same trajectory path  34 . With this information a computer system (not shown) attached to optical sensor  14  can detect and calculate the location of different objects  28  after being projected through the air off the end of the conveyor  24 . 
         [0013]    The speed of conveyor  24  is selected so that all of the materials  26  are launched out over the end of conveyor  24  into a far bin  30 B and onto a conveyor  32 B. The optical sensor  14  is programmed via software in the computer system to detect the shape, type of material, color or levels of translucence of particular objects  28 . For example, the computer system connected to optical sensor  14  may be programmed to detect the type of plastic material associated with plastic bottles. 
         [0014]    Any objects  28  having the preprogrammed types of materials are detected by the optical sensor  14  when passing through a light beam  16 . The computer system connected to the optical sensor  14  sends a signal activating a high pressure ejection air nozzle  20 . The ejection nozzle  20  releases a blast of air  22  that knocks the detected objects  28  downward out of normal trajectory path  34  into near bin  30 A and onto conveyor  32 A. The other materials  28  continue to travel along trajectory path  34  into the far bin  30 B and onto conveyor  32 B. 
         [0015]    Referring to  FIG. 2 , theoretically, all of the materials  26  should move along the same trajectory path  34 . However, in reality different materials  26  “fly” off of the conveyor  24  differently for several different reasons. For example, pieces of paper, cardboard, or Styrofoam  26 C may have aerodynamic characteristics that due to air resistance cause those objects to flip upward, flip downward, or just generally drift downward after being launched from conveyor  24 . The air resistance experienced by these objects (lack of aerodynamics), causes the paper, cardboard, or Styrofoam  26 C to deviate from the normal trajectory path  34  and fall short into the near bin  30 A. 
         [0016]    The projection of objects  26  and/or air blasts  22  may also create air turbulence  42  that alters the normal trajectory path  34  of other objects  26 B. For example, the air disturbance  42  may push down, raise up, or tumble relatively light objects  26 B. This air disturbance  42  causes the objects  26 B to deviate out of the normal trajectory path  34  and unintentionally drop into the near bin  30 A. 
         [0017]    Other objects may collide into each other while being launched from conveyor  24 . For example, an object  26 A may run into or slightly attach onto bottle  28 A while being projected from conveyor  24 . The frictional force created when object  26 A comes in contact with the bottle  28 A may cause object  26 A to deviate out of trajectory path  34  and unintentionally drop into near bin  30 A. 
         [0018]    The optical air separation system  12  may also use large bins  30 A and  30 B to catch the different separated materials  28  and  26 , respectively. One possible disadvantage of large bins is that slight variances in the normal trajectory path  34  can cause objects to fall into the wrong bins. Accordingly, any of the trajectory disturbances described above are more likely to cause material to fall into the wrong bin. 
       Cross Flow Air Separation 
       [0019]      FIG. 3  shows a cross air current system  48  that improves the consistency of material separation. The cross air current system  48  includes an air nozzle  52 , alternatively referred to as an “air knife,” that creates a cross air current  50  in a direction generally along the trajectory path  34 . The cross air current  50  reduces at least some of the air resistance that material  26  normally experiences after being projected from the conveyor  24  ( FIG. 2 ). The positive airstream provided by the cross air current helps material  26  travel along the desired trajectory path  34 , thus counteracting some of the trajectory deviation problems described above. 
         [0020]    As described above, one cause of trajectory path deviation is the different aerodynamic characteristics of the different materials  26 . The cross air current  50  prevents these projected materials from having to fight dead air, which equates to wind resistance or lack of aerodynamics. As previously shown in  FIG. 2 , dead air resistance caused certain objects such as paper, cardboard, or Styrofoam  26 C′ to flip vertically upward, flip vertically downward, or simply run out of speed after being projected off the end of conveyor  24  ( FIG. 2 ). The increased air resistance caused these objects  26 C to lose speed and incorrectly drop into near bin  30 A. 
         [0021]    However, the cross air current  50  shown in  FIG. 3  removes at least some of this dead air resistance and as a result, the paper, cardboard, Styrofoam, etc.  26 C is less likely to flip and/or run out of speed after being projected from conveyor  24 . Instead, the cross air current  50  allows the paper, cardboard, or Styrofoam  26 C to maintain theoretical aerodynamic characteristics and continue along trajectory path  34  into the correct far bin  30 B. 
         [0022]    In certain embodiments, the speed of material  26  coming off of conveyor  24  and the corresponding speed of cross air current  50  may both be between 7-12 feet per second (FPS). It has been discovered that approximately 10 FPS on the infeed material conveyor  24  provides good separation of material into a single layer as the material  26  is being carried and launched off of conveyor  24 . The 10 FPS projection speed also provides controlled launching of the material  26  along trajectory path  34 . Of course other conveyor speeds and cross air current speeds may be used depending on the material being separated and the configuration of the cross air current system  48 . 
         [0023]    In one embodiment, the air knife  52  generates a cross air current  50  that is either substantially parallel to the trajectory path  34 , in line with the trajectory path  34 , or possibly in a slightly upward intersecting direction with trajectory path  34 . The air nozzle  52  can be rotated or moved so that the cross air current  50  is aligned in a variety of different directions with respect to trajectory path  34 . The alignment of air current  50  in relationship to trajectory path  34  may be changed according to the type of materials  26  that need to be separated, the speed of conveyor  24 , the height of the conveyor  24  above bins  30 , the size of bins  30 , etc. 
         [0024]    In one embodiment, the mid-range airspeed of cross air current  50  is approximately equal to the mid-range travel speed of material  26 . The location  27  of the mid-range airspeed is approximately half way between the air bar  22  where the ejection air nozzle  20  blasts downward air pressure and the splitter plate  31  that separates the first near bin  30 A ( FIG. 4 ) from the far bin  30 B ( FIG. 4 ). 
         [0025]    The speed of air, coming off the face of the air knife  52  is much faster than 10 FPS. This is required due to the compressibility of air which creates exponential reduction in speed compared to distance off the air knife face. It has been discovered that air speeds of 20,000 to 30,000 FPS with air knife system pressures of 25-35 inches of water provide the necessary force and speeds to properly interface with the material traveling at 10 FPS off the end of the conveyor. Thus the air speed off the face of the air knife may have to be faster than the mid-range air speed, in order to obtain the desired air speed at location  27 . Of course, these speeds and pressures can vary in different embodiments according to the types of materials that need to be separated. 
         [0026]    Referring to  FIG. 4 , in this example, the cross air current system  48  separates polyethylene terephthalate (PET) and/or high density polyethylene (HDPE) bottles, jugs, containers, etc.  28  from other objects in material stream  26  or comingled recyclable material stream. However, it should again be understood that the cross air separation system  48  can be used to separate any detectable object from a material stream. 
         [0027]    Another trajectory issue described above in  FIG. 2  relates to air turbulence created by the air  22  blasted out of air ejection nozzle  20  and created by objects projected out from conveyor  24 . As described above in  FIG. 2 , there was previously very little continuous air flow around the ejection area at the end of conveyor  24 . As a result, the projection of materials  26  and the air blasts  22  created a substantial amount of air turbulence  42 . This air turbulence  42  disrupted the normal trajectory path  34  of some lighter materials  26 B and caused those materials to incorrectly fall into the near bin  30 A. 
         [0028]    The cross air current  50  creates a layer of continuously flowing air that effectively blazes a path through the air turbulence  42  allowing the material  26 B to continue along trajectory path  34  into the correct far bin  30 B. The cross air current  50  effectively carries away some of the air turbulence  42  resulting in more surgical, higher precision blasts of air  22  from ejection air nozzle  20 . An analogy would be throwing a rock into a quiet pond versus throwing a rock in a swift river. The rock creates large wide spreading ripples in the quiet pond. However, the rock creates much less noticeable disturbance in the swift river. 
         [0029]    The air blasts  22  generated by the ejection air nozzle  20  have more force than the cross air current  50 . Therefore, the air blasts  22  can still blast through the cross air current  50  and push certain detected objects  28 A downward into the near bin  30 A. At the same time, the material  26  around the ejected object  28 A is more insulated from the air blasts  22  by the layer of cross air current  50  and is therefore less likely to deviate out of trajectory path  34 . 
         [0030]      FIG. 5  shows how cross air current  50  compensates for “friction forces” that might exist between different projected materials  26 . For example, as previously described in  FIG. 2 , a projected object  26 A might run into bottle  28 A, lose velocity, and incorrectly drop into near bin  30 A. 
         [0031]    The cross air current  50  offsets these friction forces by helping all of these objects to flow e along the trajectory path  34 A at the same speed. The cross air current  50  in  FIG. 5  also provides more separation of material launched off the conveyor  24 . For example, the cross air current  50  may blow the object  26 A off of bottle  28 A thus helping the object  26 A continue along trajectory path  34  into the desired far bin  30 B. 
       Pneumatic Transfer 
       [0032]      FIG. 6  shows a pneumatic transfer system  60  used for transporting the PET and/or HDPE objects  28 , such as plastic bottles, from the cross air current separation system  48  to a storage bin  61 . The pneumatic transfer system  60  includes a blower  68 , air flow controller (venturi)  64 , and a series of air chambers (pipes)  62 . The air flow controller  64  in one embodiment is a metal plate or door that can be either rotated about the side of the pipe  62  and/or slid back and forth inside of air chamber  62 . 
         [0033]    The plastic bottles  28 A are blasted down into near bin  32 A by the ejection air nozzle  20  as described above. Attached to the bottom of the near bin  32 A is a vertical air chamber  62 A. This air chamber transports the material via gravity and potentially other pneumatic forces depending on how the system is tuned, down to the main horizontal air chamber # 62 D. Once the objects  28 A transfer into air chamber  62 D, the air  86 A from blower  68  carries the objects  28 A up through air chamber  62 B into bin  61 . 
         [0034]    Due to the nature of the pneumatic transfer system  60 , the air flow  86 A going through the venturi  64  can create a vacuum in vertical air chamber  62 A. The downward air flow  86 B created by the vacuum can undesirably draw relatively light material down into the near bin  30 A. The cross air current  50  offsets some of this downward air flow  86 B further allowing material to travel over near bin  30 A and drop into far bin  30 B. 
         [0035]      FIG. 7  shows an alternative pneumatic transfer system  80  that provides more balanced air flow. The pneumatic transfer system  80  includes a second air flow controller (venturi)  88  located at the L-shaped horizontal to vertical elbow section between air chamber  62 D and air chamber  62 B. Depending on the nature of material and air flow characteristics, the second air flow controller  88  can be located in other locations in air chamber  62 B. Air flow controller  88  in one embodiment is a metal plate or door that rotates between air chamber  62 D and air chamber  62 B. 
         [0036]    The two air flow controllers  64  and  88  control the amount of air allowed to pass through air chambers  62 A,  62 B, and  62 D respectively, by varying the size of the opening in the air chambers  67  and  65 , respectively. The second air flow controller restricts air flow  86 C through the air chamber  62 B causing back pressure back up into air chamber  62 A. The back pressure eliminates some or all of the previous downward air flow  86 B ( FIG. 6 ) previously created by the vacuum in air chamber  62 A. 
         [0037]    The combination of air flow controllers  64  and  88  can further be arranged so that a positive upward air flow  86 E blows back up through air chamber  62 A into the near bin  30 A. This positive upward air pressure  86 E can work separately, or in combination with cross air current  50 , to help carrying light material over near bin  30 A and into the far bin  30 B. As the opening  65  between air chamber  62 D and air chamber  62 B is made smaller by air flow controller  88 , more back pressure air flow  89 E is created in air chamber  62 A. Additional positive upward air flow  86 E can be created by further reducing the size of the opening  65  with air flow controller  88  and/or increasing the size of the opening  67  in air chamber  62 A with the air flow controller  64 . 
         [0038]    In another embodiment, another air chamber (pipe)  62 C taps off of pipe  62 B at the main outlet of the blower  68  and provides the air flow for the cross air current  50  output by the air knife  52 . A third air flow controller (venturi)  82  is located in pipe  62 C and is used for controlling the amount of cross air current  50  output by air knife  52 . 
         [0039]    The same blower  68  can be used for providing the cross air current  50  to air knife  52  and for generating the air flows  86  in air chambers  62 A  62 B and  62 D. Using the same air supply from blower  68  self balances the different air flows  50 ,  86 A,  86 B, and  86 C. 
         [0040]    For example, it is easier to adjust or synchronize multiple different air flows when they all originate from a common air supply  68 . Since there is one common air supply used for all of these air flows, increasing the cross air current  50  coming from air knife  52 , for example, will correspondingly reduce some of the air flow  86 A. This in turn can reduce the upward air flow  86 E in air chamber  62 A. Similarly, reducing the amount of air allowed into air chamber  62 C can increase the amount of positive air flow  86 E moving vertically up from air chamber  62 A. Accordingly, the entire air control system self balances to provide more predictable material trajectory and transfer control. 
         [0041]    Having described and illustrated the principles of the invention in a preferred embodiment thereof, it should be apparent that the invention may be modified in arrangement and detail without departing from such principles. I/we claim all modifications and variation coming within the spirit and scope of the following claims.