Abstract:
A firebox apparatus is adapted for transport on a vehicle having a roll-off hoist mechanism by providing parallel guides on the underside of a supporting skid assembly of the firebox apparatus for engaging siderails of a tiltable roll-off track of the hoist mechanism, and by providing reinforced front and rear portions connecting parallel longitudinal skid members to maintain an opening at the bottom of the firebox apparatus yet make the firebox apparatus sufficiently sturdy to withstand loads encountered during loading an unloading from the transport vehicle. The firebox apparatus includes an air curtain system for limiting pollution resulting from incineration of waste. The present invention enables easy installation and removal of the firebox apparatus in crowded environments, such as urban environments, to cleanly burn waste.

Description:
FIELD OF THE INVENTION 
     The present invention relates to the field of waste disposal, and in particular waste disposal by incineration. 
     BACKGROUND OF THE INVENTION 
     Incinerating waste is a known alternative to burying waste or transporting it to another location. In order to reduce ash and smoke released during waste incineration (particulate release), a flow of high velocity air has been used to provide an “air curtain” over a fire pit or firebox in which the waste is burned. U.S. Pat. Nos. 4,756,258 and 5,415,113 describe portable apparatus for air curtain incineration. The former patent teaches a fan and manifold assembly that can towed to the edge of a fire pit, such as may be found at a landfill site. The latter patent teaches a firebox apparatus including a fan and manifold assembly mounted on a support skid for transport on a flatbed truck to a desired site, for example a development site where vegetation is being cleared. 
     Neither of the portable solutions mentioned above is suitable for use in a congested urban environment. The apparatus of U.S. Pat. No. 4,756,258 requires a fire pit, something which is not available or readily provided in an urban setting where subterranean utility infrastructure is covered by pavement or concrete. The apparatus of U.S. Pat. No. 5,415,113 must be lifted from and loaded onto a flatbed truck by a crane or lift, making it difficult and disruptive to install in crowded or confined locations. 
     U.S. Pat. No. 7,063,027 discloses a portable air-curtain incinerator that suffers the same portability drawback as the incinerator disclosed in U.S. Pat. No. 5,415,113. 
     What is needed is a portable firebox apparatus that loads onto and unloads from a transport vehicle having a conventional tiltable roll-off hoist and tension cable, such that the firebox apparatus may be transported to an urban environment and unloaded in a confined space, and later loaded back onto the transport vehicle, with relative ease. 
     SUMMARY OF THE INVENTION 
     It is therefore an object of the present invention to provide a firebox apparatus that is capable of being loaded onto and unloaded from a transport vehicle equipped with a roll-off hoist mechanism of a type having a retractable tension cable and a tiltable roll-off track. 
     The object is achieved by a firebox apparatus generally comprising a firebox including a pair of laterally-spaced longitudinal side walls connected by a front wall and a rear wall to define a combustion chamber having an open bottom and an open top; and a frame for supporting the walls of the firebox, the frame including a skid assembly at a base of the frame, wherein the skid assembly includes a pair of laterally-spaced longitudinal skid members connected by a front portion and a rear portion to define an internal opening registering with the open bottom of the combustion chamber, and a pair of parallel guides fixed to at least one of the front portion and the rear portion for guiding the firebox apparatus as the firebox apparatus travels in a longitudinal direction relative to the roll-off track of the transport vehicle. In an embodiment depicted herein, a pair of parallel guides are fixed to the front portion of the skid assembly and another pair of parallel guides are fixed to the rear portion of the skid assembly. 
     The front portion of the skid assembly may include a pair of laterally-spaced cylindrical rollers journalled at a forward location of the front portion to rotate about a transverse axis to rollingly engage respective upwardly facing surfaces of the roll-off track&#39;s siderails. 
     The firebox apparatus of the present invention further comprises an air curtain system for blowing air across the open top of the combustion chamber. A control room provided atop the front portion of the skid assembly houses a control unit for operating a blower in communication with a manifold arranged along the top of a longitudinal side wall of the firebox, whereby an air curtain may be generated. 
     The present invention extends to a method of transporting a firebox apparatus to and from an incineration location, the firebox apparatus including a firebox defining a combustion chamber having an open top, and an air curtain system adjacent the firebox for blowing air across the open top of the combustion chamber, the method comprising the steps of parking a transport vehicle endwise adjacent to the firebox apparatus, the transport vehicle including a hoist mechanism having a retractable tension cable and a tiltable roll-off track; attaching the retractable tension cable to the firebox apparatus; operating the hoist mechanism to pull the firebox apparatus onto the tiltable roll-off track; driving the transport vehicle to the incineration location; and operating the hoist mechanism to unload the firebox apparatus from the tiltable roll-off track onto the ground at the incineration location. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWING FIGURES 
       The nature and mode of operation of the present invention will now be more fully described in the following detailed description of the invention taken with the accompanying drawing figures, in which: 
         FIG. 1  is an orthogonal view of a roll-off firebox apparatus formed in accordance with an embodiment of the present invention; 
         FIG. 2  is a top plan view of the roll-off firebox apparatus shown in  FIG. 1 ; 
         FIG. 3  is cross-sectional view of the roll-off firebox apparatus taken generally along the line A-A in  FIG. 2 ; 
         FIG. 4  is an orthogonal view of a supporting skid assembly of the firebox apparatus; 
         FIG. 5  is a bottom plan view of the supporting skid assembly shown in  FIG. 4 ; 
         FIG. 6  is cross-sectional view of the a supporting skid assembly taken generally along the line B-B in  FIG. 5 ; 
         FIG. 7  is a perspective view showing alignment of a front portion of the skid assembly with a tiltable roll-off track of a transport vehicle; and 
         FIGS. 8A-8D  are a series of side elevational views showing a roll-off firebox apparatus of the present invention being unloaded from a transport vehicle equipped with a hoist mechanism having a retractable tension cable and a tiltable roll-off track. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     A roll-off firebox apparatus  10  formed in accordance with an embodiment of the present invention is shown in  FIGS. 1-4 . Apparatus  10  generally comprises a firebox  12  having a pair of longitudinal side walls  13  and  14 , a front wall  15  and a rear wall  16  cooperating to define a combustion chamber  17  having and open top  18  and an open bottom  19 . Rear wall  16  may be formed by double doors  16 A and  16 B which are each hinged along one side to open outwardly. During incineration, the ground effectively forms the bottom of combustion chamber  17 . Each wall  13 - 15  is lined on the inside with a layer of refractory material in the form of refractory panels  20 . The inside of each door  16 A,  16 B is similarly lined with a refractory panel  22 . Each panel  20 ,  22  includes a steel sub-frame  24 ,  26  thereabout. The firebox structure described above may be manufactured as taught in commonly-owned U.S. Pat. No. 5,415,113, which is incorporated herein by reference in its entirety. 
     Each panel/sub-frame  20 / 24  forming walls  13 - 15  and each panel/sub-frame  22 / 26  forming doors  16 A,  16 B is supported by a frame  28  of suitable strength. Frame  28  includes a skid assembly  30  at its base. Skid assembly  30  has a pair of laterally-spaced longitudinal skid members  32  and  34  connected by a front skid portion  46  and a rear skid portion  48 . 
     Skid members  32 ,  34  may each be made of a length of 8″×10″ rectangular steel tubing having a wall thickness of ½″ for durability and longevity. The ends of skid members  32 ,  34  may be closed by welding a ½″ thick plate over each end. Vertical and horizontal support members  36  and  38  for the refractory panels  20  may be fabricated with W6×25# wide flange I-beams. Each of the panels  20  is held in place at its top to the web of its corresponding horizontal I-beam  38  by at least two ⅜″ steel clips  42 . A length of 2½″×⅜″ angle bar  40  is welded along the top of each skid member  32 ,  34  for receiving at least two such clips  42  fixed near the bottom of each panel  20 . A ¼″ gap is left between the panels  20  to accommodate expansion and contraction from the generated heat. Lengths of ¼″×2″ flat bar are welded respectively to the back of each panel  20  to cover this ¼″ gap. Each door  16 A,  16 B is hung from another vertical support member  44 , made from a W8×31# wide flange I-beam, using four hinge mounts, made out of ½″ steel plate, welded into the web of its vertical beam  44 . All vertical support members  36  and  44  are secured in place with 3″×4.1# channel gussets at both the top and bottom. 
     Reference is also made now to  FIGS. 5 and 6  of the drawings. Skid assembly  30  includes front portion  46  and rear portion  48  extending laterally to connect skid members  32 ,  34  to one another. As may be understood, skid members  32 ,  34  and front and rear portions  46 ,  48  cooperate to define an internal opening  50  registering with the open bottom  19  of combustion chamber  17 . 
     In the embodiment shown, front portion  46  includes a pair of longitudinally-spaced cross-members  52 ,  54  each having its opposite ends welded to the inner side faces of skid members  32 ,  34 . Cross-members  52 ,  54  may be fabricated from lengths of 8″ square steel tubing. A pair of intermediate brace members  56 ,  58  may be arranged to extend in the longitudinal direction of skid assembly  30 . Brace members  56 ,  58  may be formed from lengths of structural steel I-beam and/or channel stock and situated such that a lower flange of each brace member is offset just above the bottom faces of cross-members  52 ,  54 . Front portion further includes a bottom plate  60  welded to the lower flanges of brace members  56 ,  58 , such that a downwardly facing surface of bottom plate  60  is flush with the bottom faces of cross-members  52 ,  54 . Bottom plate  60  may be formed of one or more pieces of steel plate, with ½″ thick plate being considered suitable in the context of the present invention. 
     Front portion  46  is provided with a pair of parallel guides  62 ,  64  fixed to the downwardly facing surface of bottom plate  60  and to the bottom wall surfaces of cross-members  52 ,  54 . Guides  62 ,  64  extend in a longitudinal direction of skid assembly  30  and are spaced from one another by a distance corresponding to the width of a roll-off track of a transport vehicle, as will be described in greater detail below. A front extension  65  of each guide  62 ,  64  projects forward from cross-member  52  and cooperates with a corresponding yoke member  66  offset laterally inward therefrom in supporting an axle pin  67  to journal a roller  68  for rotation about a laterally extending axis. In the embodiment shown, rollers  68  are formed as cylindrical rollers and are arranged such that the downwardly facing surface of bottom plate  60  is substantially tangential to an underside of the roller. Guide extensions  65  may have an arcuate leading lower edge  69  for smooth engagement with rollers on a roll-off track of a transport vehicle, as will be described later herein. Gussets  71  welded to cross-member  52  and yoke members  66  may be used to provide added strength in supporting rollers  68 . Front portion  46  of skid assembly  30  is also equipped with a cleat member  70 , which is broadly intended to mean any suitable male member or female configuration used to connect a tension cable of a transport vehicle hoist mechanism to firebox apparatus  10 . In the depicted embodiment, cleat member  70  is a hooked member welded to a top face of cross-member  52  midway between skid members  32 ,  34 . 
     Rear portion  48  of skid assembly  30  includes a cross-member  72  having its opposite ends welded to the inner side faces of skid members  32 ,  34 . Cross-member  72  may be fabricated from a length of 8″ square steel tubing. A bottom plate  74  is welded at its lateral side edges to the inner side faces of skid members  32 ,  34 , at its rear edge to a front face of cross-member  72 , and at its front edge to a laterally extending spacing bar  76 . Rear portion  48  further includes a platform  77  between skid members  32 ,  34 . Platform  77  has a top plate  78  welded at its front edge to spacing bar  76  and at its rear edge to the front face of cross-member  72 . Bottom plate  74  and top plate  78  may each be formed of one or more pieces of steel plate, such as ½″ thick steel plate. In the embodiment now being described, the downwardly facing surface of bottom plate  60  of front portion  46  and the downwardly facing surface of bottom plate  74  of rear portion  48  are substantially coplanar. 
     As best seen in  FIG. 4 , top plate  78  is tilted relative to horizontal, whereby platform  77  has an upper surface that is inclined upwardly as it extends in a direction from front to rear of skid assembly  30 . The width (lateral extent) of top plate  78  is slightly less than the distance between opposing inner side faces of skid members  32 ,  34  such that clearance is provided between the sides of platform  77  and the inner faces of skid members  32 ,  34  to define a pair of longitudinally extending channels  80 ,  82 . Channels  80 ,  82  each receive a rear refractory panels  20  of a respective side wall  13 ,  14  of firebox  12 , such that bottom plate  74  of rear portion  48  provides additional support and stability to side walls  13 ,  14 . 
     Skid assembly  30  may be equipped with a second pair of parallel guides  84 ,  86  fixed to the underside of rear portion  46  in alignment with the first pair of parallel guides  62 ,  64  fixed to the underside of front portion  46 . Guides  84 ,  86  may be welded to the downwardly facing surface of bottom plate  74  and to the bottom face of cross-member  72 . 
     In accordance with an embodiment of the present invention, guides  62 ,  64  and  84 ,  86 , excluding guide extensions  65 , are defined by steel angle segments having one leg welded in surface-to-surface engagement with an associated bottom plate  60  or  74  and another leg depending downwardly to provide a planar guide surface. The planar guide surfaces of guides  62 ,  64  are identified as  62 A and  64 A in  FIGS. 5 and 6 , while the planar guide surfaces of guides  84 ,  86  are identified as  84 A and  86 A in  FIGS. 3 and 5 . This configuration of guides  62 ,  64 ,  84 , and  86  is easy to fabricate and provides reliable guidance as firebox apparatus  10  moves along a roll-off track of a transport vehicle. 
     Firebox apparatus  10  further comprises an air curtain system associated with firebox  12  for blowing air across the open top  18  of combustion chamber  17  to reduce the escape of particulates and byproducts into the atmosphere during incineration. As seen in  FIG. 1 , a control room  90  is provided atop front portion  46  of skid assembly  30  for housing a control unit  91 , a blower  92  operatively connected to control unit  91 , and a manifold  93  in communication with blower  92 . Manifold  93  is arranged to extend along the top of longitudinal side wall  14 , and serves to direct airflow across combustion chamber  17 . A floor plate  94  may be provided in control room  90  atop cross-members  52 ,  54  and brace members  56 ,  58  to support control unit  91 . The air curtain system may be constructed substantially as taught in U.S. Pat. No. 5,415,113 referenced above. 
     Reference is made now to  FIG. 7 , which illustrates alignment of a front end of firebox apparatus  10  with a tiltable roll-off track  102  of a transport vehicle  100  ( FIGS. 8A-8D ) and attachment of a retractable tension cable  104  of the transport vehicle to the firebox apparatus  10 . As will be understood, roll-off track  102  and tension cable  104  are parts of a conventional roll-off hoist mechanism  101  of transport vehicle  100 . Roll-off track  102  may be progressively and reversibly is tilted by operation of a pair of hydraulic actuators acting between the vehicle chassis and a front end of the roll-off track  102  from a generally horizontal position to a fully tilted position wherein a rear end of track  102  engages the ground, as shown in  FIG. 6 . As may be seen, roll-off track  102  includes a pair of parallel siderails  106 ,  108  each having an upwardly facing surface  110  and an outwardly facing surface  112  (only one of the outwardly facing surfaces  112  being visible in  FIG. 7 ). Rollers  68  are located for alignment with siderails  106 ,  108  and will engage upwardly facing surfaces  110  of the siderails during a roll-off or pick-up operation as described below. Guide surfaces  62 A,  64 A,  84 A, and  86 A will slideably engage outwardly facing surfaces  112  of siderails  106 ,  108  to guide firebox apparatus  10  as it travels in a longitudinal direction relative roll-off track  102 . 
     It should be realized that other types of guides may be employed without straying from the invention. For example, guides which incorporate a series of rollers spaced longitudinally along a guide body for tangential rolling contact with a roll-off track may be used. Guides providing intermittent guide surfaces, rather than a continuous guide surface as shown, could also be used to reduce friction. 
     Loading and of firebox apparatus  10  onto a transport vehicle  100  and unloading of the firebox apparatus at an incineration site will now be described with reference to FIGS.  7  and  8 A- 8 D. Loading is carried out by maneuvering transport vehicle  100  such that its rear end is adjacent a front end of firebox apparatus  10  and siderails  106 ,  108  of the transport vehicle&#39;s roll-off track  102  are aligned with rollers  68  and guides  62 ,  64 . The hoist mechanism is adjusted to position roll-off track  102  in its fully-tilted position, and an attachment end of tension cable  104  is coupled to cleat member  70 . Hoist mechanism  101  is then operated to progressively pull firebox apparatus  10  onto roll-off track  102  and lower the front end of roll-off track until firebox apparatus  10  rests in a horizontal position on roll-off track  102 . Firebox apparatus may then be secured to transport vehicle  100  by conventional means and driven to an incineration cite. As may be understood from  FIGS. 8A through 8D , firebox apparatus  10  may be unloaded from transport vehicle  100  in a substantially reverse manner, wherein gravity will aid the unloading process as the front end of roll-off track  102  is slowly raised. Once the rear end of firebox apparatus  10  firmly engages the ground as depicted in  FIG. 8C , the transport vehicle  100  is slowly driven forward to allow the front end of the firebox apparatus to progress downward along tilted roll-off track  102  until the firebox apparatus is completely supported by the ground. Following unloading, tension cable  104  is detached from cleat member  70  and the firebox apparatus is ready for start-up and normal operation. 
     As will be appreciated from the foregoing description, the supporting skid assembly of firebox apparatus  10  distributes and supports loads applied to firebox apparatus  10  during unloading and loading with respect to transport vehicle  100 , and guides the firebox apparatus as it moves along roll-off track  102 . With the present invention, it is now possible to efficiently install and use environmentally friendly air-curtain incinerators in urban environments wherever and whenever the need arises.