Patent Publication Number: US-10330452-B2

Title: Apparatus and method to render air bag inflators and other low level detonatable devices inert for recycling

Description:
RELATED APPLICATION 
     This application claims the benefit of U.S. Provisional Patent Application Ser. No. 62/532,724, entitled Apparatus and Method to Render Air Bag Inflators and other Low Level Detonatable Devices Inert for Recycling, filed on Jul. 14, 2018, the contents of which are incorporated herein by reference in their entirety for all purposes. 
    
    
     BACKGROUND 
     Technical Field 
     This invention relates to metal and chemical recycling, and more particularly to an automated system for rendering air bag inflators and other low level detonatable devices inert for recycling. 
     Background Information 
     Air bag units for automobiles are widely used throughout the world. They are installed to protect passengers during a crash. Generally, an air bag unit comprises an air bag and an inflator therefor. Upon impact the inflator is actuated and releases gas to rapidly expand the air bag. The inflated air bag forms a cushion between the passenger and, for example, the steering wheel to prevent the passenger from impacting against the steering wheel as the automobile rapidly decelerates. 
     The inflator has a metallic housing. A gas generant, e.g., in the form of a chemical explosive propellant, is disposed in the housing along with an ignition means for igniting the propellant. The ignition means may be actuated by mechanical shock or by electrical signals generated by suitable sensors. 
     Typically the housing for an air bag inflator is made of, for example, carbon steel, aluminum alloy and stainless steel. The propellant may have primary components such as NH 4 NO 3  (ammonium nitrate). 
     When automobiles are scrapped, they are usually compressed. If an automobile is compressed with an unused air bag unit therein, there is the risk that the air bag unit will explode. In order to avoid this risk, the scrapping process is carried out only after actuation of the air bag inflator. The following disposal instructions may be provided to effect actuation:
         1. For electric air bag inflators a prescribed current is applied by wires leading from a battery to actuate the inflator. This may be accomplished either with the device in the car or may be accomplished by removing, for example, the steering wheel from the car.   2. For mechanical air bag inflators the inflator is removed from the car, placed within scrapped or used tires and then mechanically actuated.       

     While conventional approaches may be suitable for processing small numbers of air bag inflators, a need exists for an automated system and method for efficiently rendering large quantities of air bag inflators and other low level detonatable devices inert for recycling, such as to provide manufacturers and automotive scrapping operations with the option of shipping undeployed inflators to a third party for safe destruction and recycling. 
     SUMMARY 
     The appended claims may serve as a summary of the invention. 
     The features and advantages described herein are not all-inclusive and various embodiments may include some, none, or all of the enumerated advantages. Additionally, many additional features and advantages will be apparent to one of ordinary skill in the art in view of the drawings, specification, and claims. Moreover, it should be noted that the language used in the specification has been principally selected for readability and instructional purposes, and not to limit the scope of the inventive subject matter. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention is illustrated by way of example and not limitation in the FIGURE of the accompanying drawings, in which like references indicate similar elements and in which: 
         FIG. 1  is a schematic representation of an embodiment of the present invention, including optional variations thereof. 
     
    
    
     DETAILED DESCRIPTION 
     It should be understood at the outset that, although exemplary embodiments are illustrated in the figures and described below, the principles of the present disclosure may be implemented using any number of techniques, whether currently known or not. The present disclosure should in no way be limited to the exemplary implementations and techniques illustrated in the drawings and described below. Additionally, unless otherwise specifically noted, articles depicted in the drawings are not necessarily drawn to scale. In addition, well-known structures, circuits and techniques have not been shown in detail in order not to obscure the understanding of this description. The following detailed description is, therefore, not to be taken in a limiting sense, and the scope of the present invention is defined by the appended claims and their equivalents. 
     General Overview 
     The present inventor has recognized that in order to recycle as scrap certain devices that may or may not be deemed hazardous, such as according to one or both of DOT (U.S. Department of Transportation) or RCRA (Resource Conservation Recovery Act 1976) any chemicals must be separated from the metal or plastics which are to be recycled. The present inventor has also recognized that in many instances it would be inadvisable to batch feed detonable materials directly into a kiln or oven which is not designed to contain deflagrations or detonations. The inventor further recognized that conventional shredding approaches would be inappropriate for charged detonable devices due to the potential for dangerous detonations and inadequate separation of active chemicals from shredded materials (e.g., metals). 
     The embodiments shown and described herein address these issues by shredding charged detonable devices, e.g., charged air bag inflators, in a continuous process within a special chamber while in contact with water, e.g., via irrigation means such as a water spray/shower or bath, which reduces chances of sparking, eliminates heat buildup and begins to react (hydrolyze) and dissolve the chemical constituents. Hydrolysis of the chemical constituents is completed in a water sump from which the solids are then removed with a dewatering screw system. Water used for the hydrolysis is then pumped off for hazardous waste disposal/recycling. Optionally, the scrap content is then further processed in a high temperature kiln or oven to destroy any residue and render the material inert/non-hazardous for scrap recycling. 
     The present inventor conducted a number of tests on sample devices to help devise and determine the effectiveness of the particular arrangement of elements shown and described herein to adequately render inert various size air bag inflator devices and expose their chemical contents. As discussed in greater detail hereinbelow, particular embodiments are designed for continuously shredding batches of air bag inflators or similarly combustible materials, along with cardboard boxes or other receptacles in which the bulk shipments of air bag inflators may be transported. It should also be noted that the air bag inflators may be shredded along with their associated fabric bag components. Embodiments include a closed chamber with rotary feeder and irrigation means (e.g., water bath or spray as shown) with a low speed dual stacked hydraulic shredder system that opens intact air bag units while being irrigated by the irrigation means (e.g., under the water spray or submerged in a water bath) to provide for hydrolysis of the chemical contents. The material is then fed to a secondary irrigation means, such as the water sump as shown, to complete the hydrolysis of the chemical contents. The metal shards are dewatered/separated from the hydrolysate e.g., using an inclined screw, and then staged in roll off boxes for recycling. The metal scrap is optionally baked in an oven or kiln to destroy any remaining chemical residue prior to recycling. Embodiments are configured to process approximately 80,000 to 180,000 pounds of material per day based on operation 24 hours per day. 
     Terminology 
     As used in the specification and in the appended claims, the singular forms “a”, “an”, and “the” include plural referents unless the context clearly indicates otherwise. Although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation. All terms, including technical and scientific terms, as used herein, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs unless a term has been otherwise defined. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning as commonly understood by a person having ordinary skill in the art to which this invention belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and the present disclosure. Such commonly used terms will not be interpreted in an idealized or overly formal sense unless the disclosure herein expressly so defines otherwise. 
     Where used in this disclosure, the term ‘downstream’ refers to the direction of flow of the material (e.g., boxes  12 ) through the apparatus  5 , such as indicated by arrows a in  FIG. 1 . The term ‘upstream’ refers to a direction other than downstream. When either term ‘downstream’ or ‘upstream’ is used with reference to a component of apparatus  5 , these terms shall refer to the direction of flow of the material through such component. 
     Referring now to  FIG. 1 , embodiments of the present invention include an apparatus  5  for rendering inert and separating components of detonable devices fabricated from metal and water soluble chemical explosive propellants, for recycling. The apparatus includes a raw material feeder  10 , such as a conventional sorting table with or without rollers, a bin, and/or a hopper, for receiving material which may include the detonable devices along with related components such as shipping material/boxes as discussed hereinbelow. As mentioned hereinabove, in particular embodiments, the detonable devices are charged air bag inflators with water soluble chemical explosive propellants such as ammonium nitrate, nitroguanidine, and/or combinations thereof, although other propellants may be used. It should also be noted that air bag inflators may be of substantially any form factor, including puck shaped metallic air bag inflators typically used in automobile steering wheels, and cylindrical metallic air bag inflators typically placed on the passenger-side dashboard and elsewhere in the automobile. If the detonable devices are delivered to the apparatus  5  in conventional boxes  12 , such as fabricated from cardboard or similar materials used in the shipping industry, such boxes may be placed on feeder  10  (e.g., a table as shown) and fed to conveyor  20 . Alternatively, if the detonable devices are delivered loosely in drums instead of in boxes, feeder  10  may take the form of a metering hopper fitted to feed the devices to conveyor  20 . It should be recognized that the air bag inflators may be fed to conveyor  20  along with associated components such as the actual air bags the inflators were designed to inflate. 
     A first conveyor  20 , such as an inclined conveyor belt with buckets or cleats  22  as shown, is operatively engaged with a raw material feeder  10 , such as a roll table or hopper, to feed, at a controlled feed rate, the material/boxes  12 , from the feeder  10  to an upstream portion of a shred tower  26 . 
     Shred tower  26  is configured to convey the material in the downstream direction a therethrough, and includes a hopper  40 , a primary shredder  60  disposed within or downstream of the hopper  40 , an optional secondary shredder  62 , shown in phantom, disposed downstream of the hopper  40 , and a water sump  70  disposed downstream of the secondary shredder  62 . It should be noted that in particular embodiments, hopper  40 , as well as portions of shred tower  26  located downstream of the hopper, is fabricated from reinforced metal, e.g., steel plate of sufficient design strength and volume to contain and allow safe venting of gases while containing metal shards within the chamber in the event a detonation of a detonable device occurs during processing. In particular embodiments, the hopper  40  and shred tower  26  is closed in 360 degrees about the downstream direction, during shredding operations to prevent shard/shrapnel release, as discussed in greater detail hereinbelow. Shred tower  26  is vented to atmosphere or to an emissions control device to prevent pressure buildup in the event of a detonation. The hopper may also include a hinged perforated plate cover (not shown). Moreover, a feed valve  30  is disposed at an upstream portion of the hopper  40 , and is selectively actuatable between open and closed positions to respectively permit and prevent the material from entering the hopper from the conveyor  20 , e.g., via a drop chute as shown. In particular embodiments, valve  30  is a rotary feed valve, such as a variable speed indexing rotary paddle wheel feeder, which introduces the material into the hopper  40  at a controlled rate. The paddle wheel embodiment operates similarly to a revolving door in an office building to ensure that the valve  30  is effectively closed immediately after each box  12  is fed into the hopper  40 , to help prevent shards or shrapnel from escaping during shredding, e.g., should a detonation occur during shredding operations. It should also be recognized that in particular embodiments, the rate of actuation of valve  30  will be coordinated with the speed of the conveyor  20 , such as by driving conveyor  20  with a variable speed motor controller by a processor, such as a conventional Programmable Logic Controller (PLC), or with a hydraulic motor drive, as will be discussed in greater detail hereinbelow. 
     Shred tower  26  is also equipped with an irrigation means, which in particular embodiments includes a set of misting water spray nozzles  50  disposed at an upper portion of hopper  40  to spray water, e.g., continuously, in the hopper towards teeth of the shredder(s). This irrigation helps to prevent sparking and to begin to solubilize, separate, and hydrolyze the chemicals from the during operation of the primary shredder  60  and/or secondary shredder  62 . Optionally, the irrigation means may include a water bath, such as shown in phantom lines at  52 ′, within which one or both shredders  60 ,  62  may be immersed. Particular embodiments may also include one or more deluge water spray nozzles  52  communicably coupled to a flame detector for activation upon detection of a flame. The deluge water spray nozzles  52  are configured to supply a high volume of water, (e.g., 25 gallons per minute or more) relative to the set of misting water spray nozzles  50  (e.g., 3-8 gallons per minute). 
     Primary shredder  60  is configured to perform a course shred of the material, e.g., using relatively widely pitched teeth, including tearing open the receptacles and releasing the detonable devices, while in particular embodiments, optional secondary shredder  62  is configured to receive the material from the primary shredder, and to perform a fine shred of the material using relatively finely spaced teeth, to open the detonable devices and expose the chemical constituents. In particular embodiments, the primary shredder and optional secondary shredder each includes a 200 HP M100H shredder commercially available from SSI Shredding Systems, Inc. of Wilsonville, Oreg., or a 200 HP shredder available from Komar Industries, Inc. of Columbus, Ohio, with the secondary shredder having finer teeth than the primary shredder. 
     Water sump  70  is configured to receive and immerse the material from the secondary shredder to continue to solubilize and separate the chemicals from the metal. This tank also allows further hydrolysis activity to occur with any water soluble chemicals. Reagents or other diluents may be added depending on the chemical contents to further propagate destruction. The tank may also include a level control and pumping system to maintain water level. In particular embodiments, the water sump  70  has a capacity of at least about 500 gallons up to about 1000 gallons. 
     A second conveyor  80  is configured to lift solids including shreds of the recyclables and the receptacles from the sump, wherein residual water runs from the solids back to the sump to produce dewatered solids. In particular embodiments, conveyor  80  includes an inclined auger screw such as a dual floating screw dewatering system that pulls the scrap contents, e.g., metal, fabric, and cardboard scraps, up and out of the sump  70  along an inclined trough while allowing the water/hydrolysate to return to the sump tank. The hydrolysate may then be removed from the sump for hazardous waste disposal/recycling. 
     Second conveyor  80  feeds the dewatered solids/scrap contents to a receiving box  90 , from which the contents may be optionally fed to an incinerator, kiln or oven  110 . Incinerator  110  may be provided with a conventional off-gas treatment system(s) operating at a temperature adequate to destroy any chemical constituents to effectively burn any remaining chemical residue and shreds of the receptacles  12 , to leave metal suitable for metal scrap recycling. In particular embodiments, incinerator  110  includes a rotary reactor incinerator configured to operate at a minimum temperature of about 1000 F. In particular embodiments, the dewatered solids are fed by conveyor  80  to receiving box  90  where they may be stored and/or tested for chemical content pending introduction into the kiln or oven  110 . If testing shows that the scrap is inert and non-detonable, then the scrap will be recycled without thermal processing with kiln  110 . 
     Apparatus  5  may include one or more variable speed drives  92  operatively engaged with the first conveyor and/or the second conveyor, and optionally, with feed valve  30  and shredder(s)  60 ,  62 . A processor, such as a conventional PLC  100  is communicably coupled to the conveyors  20 ,  80  and the shredders  60 ,  62 , including the variable speed drive(s)  92 , to control operation of the apparatus  5 , such as to programmably control feed rates and timing of the various components  20 ,  80 ,  60 ,  62 , etc. For example, the processor  100  is configured to actuate a variable speed drive  92  of the first conveyor  20  to provide a controlled feed rate of one receptacle  12  every 20 to 30 seconds. 
     Processor  100  may also be programmed to provide for cascading equipment shut downs in the event of a jam or fire, as discussed hereinbelow. For example, apparatus  5  may include an electromagnetic detector  102  (e.g., an ultra violet/infrared (UV/IR) detector) disposed within shred stack  26 , e.g., to detect flames, and/or to provide optical information to an operator. Shred stack  26  may also include a hinged access door (not shown) within the closed chute extending between the primary shredder  60  and the secondary shredder  62 , to provide an operator with access to clear jams. At least one pressure sensor  104  may also be disposed in shred stack  26 , e.g., in shredder(s)  60 ,  62 , with both detectors  102  and  104  communicably coupled via the processor  100  to the various components including the shredder(s) and conveyors and irrigation means  52 ,  52 ′ and spray  50 . The processor is thus configured to alter operation of the apparatus in the event of a jam detected by the pressure sensor, and/or to increase water flow by sprayers  50 ,  52 , in the event of a flame. The processor may be configured to pause operation of components upstream of the jam until the jam is cleared, to reverse and then restart shredding x times before stopping operation of the apparatus, and/or to signal an operator of a jam. Sensor  102  may also serve as a camera to enable a user to view operation of the apparatus remotely. 
     A method for rendering inert and separating components of detonable devices fabricated from metal and water soluble chemical explosive propellants, for recycling, for example using a version of the apparatus  5  shown and described hereinabove, will now be described as illustrated in the following Table I. As shown in Table I, the method  200  commences with receiving  210 , with feeder  10 , material including a plurality of the detonable devices. With first conveyor  20 , the material is fed  212  from the feeder to the upstream portion of shred tower  26  at a controlled feed rate. The material is then conveyed  214  in a downstream direction through shred tower  26 , via feed valve  30 , which is selectively actuated at  216  between open and closed positions to respectively permit and prevent the material from entering the upstream portion of the hopper. Water is supplied  218  to hopper  40  via irrigation means  52 ,  52 ′, to substantially prevent sparking and to begin to solubilize and separate the chemicals from the metal during operation of the primary shredder and/or the optional secondary shredder. Shredder  60  shreds the material at  220 , and optional secondary shredder performs a finer shred of the material at  222 . The water sump  70  receives  224  the material from the secondary shredder to continue to solubilize and separate the chemicals from the metal. The second conveyor  80  lifts  226  the solids including shreds of the metal from sump, wherein residual water runs from the solids back to the sump to produce dewatered solids. The second conveyor  80  then feeds  228  the dewatered solids to a receiving box for metal scrap recycling. 
     
       
         
           
               
             
               
                 TABLE I 
               
               
                   
               
               
                 Method 200 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
            
               
                 210 
                 feeder receives material including detonable devices 
               
               
                 212 
                 material fed from the feeder to upstream portion of shred tower 
               
               
                   
                 26 
               
               
                 214 
                 material conveyed in a downstream direction through shred tower 
               
               
                   
                 26 
               
               
                 216 
                 feed valve 30 selectively actuated between open and closed 
               
               
                   
                 positions 
               
               
                 218 
                 water supplied to hopper 40 via irrigation means 52, 52′ 
               
               
                 220 
                 Shredder 60 shreds the material 
               
               
                 222 
                 secondary shredder optionally performs a finer shred of the 
               
               
                   
                 material 
               
               
                 224 
                 sump 70 receives material from the secondary shredder 
               
               
                 226 
                 second conveyor 80 lifts the solids including shreds of the 
               
               
                   
                 metal from sump 
               
               
                 228 
                 second conveyor feeds the dewatered solids to a receiving box 
               
               
                   
                 for metal scrap recycling 
               
               
                   
               
            
           
         
       
     
     Although the foregoing description is directed towards automotive air bag inflators, those skilled in the art should recognize that the exemplary apparatus and method described herein may be applied to render any number of low level detonatable devices inert for recycling. 
     Certain aspects of the present invention include process steps and instructions described herein in the form of an algorithm. It should be noted that the process steps and instructions of the present invention could be embodied in software, firmware or hardware, and when embodied in software, could be downloaded to reside on and be operated from different platforms used by real time network operating systems. In addition, the present invention is not described with reference to any particular programming language. It is appreciated that a variety of programming languages may be used to implement the teachings of the present invention as described herein, and any references to specific languages are provided for disclosure of enablement and best mode of the present invention. 
     Modifications, additions, or omissions may be made to the systems, apparatuses, and methods described herein without departing from the scope of the disclosure. For example, the components of the systems and apparatuses may be integrated or separated. Moreover, the operations of the systems and apparatuses disclosed herein may be performed by more, fewer, or other components and the methods described may include more, fewer, or other steps. 
     Additionally, steps may be performed in any suitable order. It should be further understood that any of the features described with respect to one of the embodiments described herein may be similarly applied to any of the other embodiments described herein without departing from the scope of the present invention. As used in this document, “each” refers to each member of a set or each member of a subset of a set. 
     To aid the Patent Office and any readers of any patent issued on this application in interpreting the claims appended hereto, applicants wish to note that they do not intend any of the appended claims or claim elements to invoke 35 U.S.C. 112(f) unless the words “means” or “step” are explicitly used in the particular claim.