Abstract:
A burner assembly comprising a burner with a body and a burner throat extending downwardly from the burner body, a carriage located below the burner and provided with a cradle, a media box configured to pivotally mate with the cradle along a horizontal axis of the media box such that the media box is supported on the carriage at the axis and can rotate on the carriage about the axis, the media box having a port that connects with the burner throat but that separates from the burner throat when the media box is tilted about its axis, and media in the media box to serve as a heat sink, where the axis is horizontally offset from the media box&#39;s center of gravity, and the media box may be rotated about the horizontal axis to allow for ready engagement and disengagement between the media box and the burner.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application derives and claims priority from U.S. provisional application 61/369,365 filed 30 Jul. 2010, which application is incorporated herein by reference. 
     
    
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
       [0002]    Not applicable. 
       BACKGROUND OF THE INVENTION 
       [0003]    This invention relates in general to furnaces for melting metals and more particularly to a regenerative furnace having an easily detached media box. 
         [0004]    Some furnaces that supply molten metal for casting and other procedures utilize regenerative furnaces to improve efficiency. The typical regenerative furnace includes an enclosure having a hearth at its bottom for containing a molten metal, which is often aluminum. At one end of the furnace the hearth has tap holes for withdrawing the molten metal. At the other end the furnace has two ports located above the hearth, and these ports are connected to burner assemblies that operate alternately for supplying hot gases to the interior of the furnace enclosure—indeed, hot enough to maintain the metal in the hearth in a molten condition. 
         [0005]    Regenerative burners operate as a duel burner unit or as a pair, i.e., burner “A” and burner “B”. While burner “A” is firing, the media in its media box is releasing stored heat to the combustion air entering the furnace to elevate the temperature of the combustion air. The combustion air flows through the media in the media box to the burner head to mix with the gas or oil for combustion in the furnace. At the same time, burner “B” is being utilized as an exhaust system for the combustion hot waste gasses. An exhaust fan draws these hot waste gasses through the burner head of burner “B” and through the media in the burner “B” media box, where the hot waste gasses elevate the temperature of the media and the media bed lining. Once the exhaust gasses downstream of the media box reach a predetermined temperature, which usually takes about 40 to 60 seconds, a pair of air/exhaust duct cycling valves reverse their positions. This switches burner “A” from the burner firing into the furnace to the burner exhausting out of the furnace, and simultaneously switches burner “B” from the burner exhausting to the burner firing. These air/exhaust duct cycling valves are used for switching and reversing the flow of hot gases and combustion air through the media beds. 
         [0006]    Each burner assembly has a burner and a media box containing a media that serves as a heat sink. The media usually takes the form of ceramic alumina spheres about one-inch in diameter. When the burner of one burner assembly operates, the hot exhaust gases that it produces discharge into the furnace enclosure above the molten metal and exhaust through the other burner assembly, passing through the media box of that other assembly. Here, the hot exhaust gasses elevate the temperature of the media as the media absorb heat from the hotter gases. After passing through the media, the hot waste gasses discharge into a lateral duct near the bottom of the media box. Then about 40 seconds later the burner shuts down and the burner of the assembly through which the hot gases formerly discharged ignites, the flow of hot gases reverses and combustion air flows through the furnace enclosure. The combustion air for that burner passes through the hot media in the media box for that burner assembly where the temperature of the combustion air is elevated as the media release their stored heat into the cooler gases. Hence, the burner operates more efficiently. Of course, the hot gases from the furnace enclosure now flow out of the idle burner assembly and elevate the temperature of the media in the media box of that assembly. The burners of the two burner assemblies alternate in supplying hot gases to the furnace enclosure, so that the molten metal within the hearth is continuously subjected to hot gases. 
         [0007]    During this process, a dross develops over the surface of the molten metal in the hearth that contains various contaminants, such as salts and oxides of aluminum, which the hot exhaust gases pick up. As the gases flow through the media in the media boxes of the two burner assemblies, they deposit some of those contaminants onto the media. These deposits will eventually clog the media. Hence, from time to time each media box is detached from the burner and the lateral duct to which it is connected and taken to a remote location where the media are cleaned and otherwise reconditioned. This is a time-consuming procedure that traditionally requires removing bolts from hot flanges where the burner and the lateral duct couple to the media box and then maneuvering the heavy media box away from the burner and duct without damaging either. 
         [0008]    It is therefore desirable to provide a burner assembly in which the media box is adapted to rapidly disconnect from and reconnect to the burner and duct associated with high a temperature furnace. The burner assembly of the present invention overcomes the problems described above and provides significant benefits over existing configurations. 
     
    
     
       DESCRIPTION OF THE DRAWINGS 
         [0009]    The illustrative embodiments of the present invention are shown in the following drawings which form a part of the specification: 
           [0010]      FIG. 1  is a side elevation view, partially broken away, of a furnace constructed in accordance with and embodying the present invention; 
           [0011]      FIG. 2  is an elevation view of the burner assembly for the furnace with the media box of that assembly withdrawn from the burner; 
           [0012]      FIG. 3  is a plan view of the media box and carriage, with the media box disengaged from the furnace; 
           [0013]      FIG. 4  is an end elevation view of the burner assembly engaged with a furnace; 
           [0014]      FIG. 5  is a side elevation view of the burner assembly showing the media box engaged by a lift truck, but not yet displaced; 
           [0015]      FIG. 6  is a side view similar to  FIG. 5 , but showing the truck tilting the media box in the carriage to separate the media box from the burner; 
           [0016]      FIG. 7  is a side view similar to  FIG. 6 , but showing truck withdrawing the media box and carriage from the burner; 
           [0017]      FIG. 8  is a side elevation view showing the media box at a media washing station; 
           [0018]      FIG. 9  is an elevation view similar to  FIG. 8 , but showing the media box tilted to discharge the media into a washing basket at the media washing station; 
           [0019]      FIG. 10  is an end elevation view showing the media box at the washing station; and 
           [0020]      FIG. 11  is a plan view of a furnace constructed in accordance with and embodying the present invention having two interchangeable burner assemblies; 
       
    
    
       [0021]    Corresponding reference characters indicate corresponding parts throughout the several views of the drawings. 
       DETAILED DESCRIPTION OF INVENTION 
       [0022]    Referring now to the drawings, a regenerative furnace A ( FIGS. 1 ,  5 - 7 ) for melting metal and maintaining the metal in a molten state includes a furnace enclosure  2  and a hearth  4  within the enclosure  2  for containing the molten metal. At its one end the enclosure  2  has two ports  6  ( FIG. 11 ) at which two separate yet interchangeable burner assemblies  10  are connected to the enclosure  2 . The burner assemblies  10  operate alternately such that while one or the other discharges hot gases, the product of combustion into the furnace enclosure  2 , the other burner assembly  10  receives the hot exhaust gasses from the furnace enclosure  2  and directs it into a laterally directed duct  12  ( FIG. 4 ). The duct  12  acts to supply gases for combustions when not acting to exhaust gasses from the furnace enclosure  2 . 
         [0023]    Each burner assembly  10  includes a burner  20  that is mounted on the furnace enclosure  2 , a media box  22  that is located between the burner  20  and the lateral duct  12 , and a carriage  24  that supports the media box  22  such, the burner assembly  10  being configured such that it can with relative ease be withdrawn away from the lateral duct  12  and burner  20 . To this end, the carriage  24  moves along rails  26  that extend past the lateral duct  12  and generally beneath the burner  20 . 
         [0024]    The burner  20  ( FIG. 1 ) includes a burner head  30  that is attached to the furnace enclosure  2  at one of the ports  6  of the enclosure  2  such that its interior opens into the interior of the enclosure  2 . The head  30  has several nozzles  32  that discharge one or more combustible gases into the head  30  where the gas or gases mix with combustion air and ignite to produce a flame that is directed through the burner head  30  and into the interior of the furnace enclosure  2 . That combustion air enters the head  30  through a burner throat  34  that extends generally downwardly from the head  30 . At its lower end, the throat  34  has a flange  36  that is disposed generally horizontally, but slightly askew such that the flange  36  is presented upwardly at a slight angle away from the enclosure with respect to the vertical. 
         [0025]    The lateral duct  12  ( FIG. 4 ) also has a flange  40 , but its flange  40  is presented upwardly at an oblique angle with respect to the horizontal, preferably at 45°. 
         [0026]    The carriage  24  ( FIG. 1 ) has a frame  50  fitted with wheels  52  that rest on and are capable of rolling along the rails  26 . The frame  50  supports side walls  54  that are spaced far enough apart to receive the media box  22  between them without binding. At their upper ends, the side walls  54  have cradles  56  that define an axis X that extends horizontally and transversely with respect to the rails  26 . The rails  26  enable the carriage  24  to move toward and away from the furnace enclosure  2 , but have stops  58  that establish a fixed position beyond which the carriage  24  cannot advance farther toward the furnace enclosure  2 . 
         [0027]    The media box  22  includes ( FIGS. 1 ,  3  &amp;  4 ) spaced apart side walls  60 , and spaced apart end walls  61  and  62 , one of which end walls  61  is positioned at the front of the box  22  where it is presented toward the furnace enclosure  2  and the other of which end walls  62  is at the back of the box  22  and is presented away from the enclosure  2 . In addition, the box  22  has a bottom wall  64  and a top lid  66 . All of the walls  60 - 62 ,  64  and the lid  66  are arranged to provide the box  22  with an orthogonal configuration. The spacing between the two side walls  60  is less than the spacing between the side walls  54  of the carriage  24 , so that the media box  22  will fit freely between the side walls  54  of the carriage  24  to be supported above the frame  50  of the carriage  24 . To this end, the box  22  has trunnions  68  that project laterally from its side walls  60  and into the cradles  56  on the side walls  54  of the carriage  24 , and when so disposed a space exists between the bottom wall  64  of the box  22  and the frame  50  of the carriage  24 . This enables the media box  22  to pivot about the axis X on the carriage  24 . Moreover, the trunnions  68  are offset horizontally from the horizontal center of gravity for the media box  22  such that the horizontal center of gravity is located between the trunnions  68  and the back end wall  62 . As a consequence, the media box  22  seeks to rotate about the axis X such that the front end wall  61  will seek to move upward, the rear end wall  62  will seek to move downward, and the media box  22  will seek to assume a tilted position on the carriage  24 . 
         [0028]    One of the side walls  60  near the bottom wall  64  has a port  70  that opens laterally and terminates at a flange  72  that lies oblique to the horizontal at an angle corresponding to the angle of the flange  40  on the lateral duct  12 . The flange  72  carries a high temperature seal  74  that interfaces with the flange  40 . Near the lid  66 , the side walls  60  have fork lift rails  78 , which can receive the tines of a fork on a lift truck. 
         [0029]    The lid  66  of the media box  22  has a vertical port  80  that opens into the interior of the box  22  near the front end wall  61 . The port  80  terminates at a pocket  82  that is large enough to receive the flange  36  on the burner throat  34 . The pocket  82  contains high temperature seal  84  at its base. The pocket  82  does indeed receive the flange  36  on the burner throat  34 , but only when the forward most wheels  52  of the carriage are against the stop  58  on the rails  26 . Moreover, when the box  22  is so disposed, its lateral port  70  aligns with the lateral duct  12 , and the flange  40  on the duct  12  seats against the seal  74  of the flange  72  on the port  70 . In addition to the vertical port  80 , the lid  66  has a re-sealable top latch door  86  for gaining access to the interior of the box  22 . Moreover, the lid  66  itself is removable from the media box  22 . 
         [0030]    The back end wall  62  also has a removable latch door  88  that when removed exposes the interior of the box  22 . Further, the end wall  62  also has a bracket  90  at which an upwardly directed force may be applied to the box  22  to tilt it on its trunnions  68  about the axis X. 
         [0031]    Normally, the box  22 , owing to the displacement of its center of gravity rearward from the trunnions  68 , seeks to tilt downwardly at its bracket  90 , but when the media box  22  is positioned such that the pocket  80  is receiving the burner throat  34 , the rotation of the media box  22  about its trunnions  68  is restrained by the burner  20 , since the flange  36  of its burner throat  34  is in the pocket  82  of the vertical port  80 . Indeed, the off-center force from the forward location of the trunnions  78  acts to seat the high temperature seal  84  that is in the pocket  82  snugly against flange  36  on the burner throat  34 . The off-center force also seats the seal  74  on the oblique flange  72  of the lateral port  70  snugly against the oblique flange  40  or the lateral duct  12 . Of course, if utilized, the pin  104  positioned in the bores  100  and  102 , must first be removed to allow the media box  22  to freely rotate about its axis X in the carriage  24 . 
         [0032]    Referring to  FIG. 1 , a through bore  100  is positioned in one of the side walls  54  of the carriage  24  such that it aligns with a bore  102  in the corresponding side wall  60  of the media box  22  when the media box  22  is rotated about its axis X to disengage the media box  22  from the furnace A. A pin  104 , configured to fit within the bores  100  and  102 , can then be placed through the through bore  100  and into the bore  102  to prevent the media box  22  from further rotating about its axis X until the pin  104  is removed. Pressure from the tendency for the media box  22  to rotate about its axis X will hold the pin  104  in place in the bores  100  and  102 . In fact, it will be necessary to apply rotational counter pressure to the media box  22  to allow the pin  104  to be readily withdrawn from the bores  100  and  102 . 
         [0033]    The media box  22  ( FIG. 1 ) contains a grid-like rack  94  that extends horizontally from end wall  61  to end wall  62  and likewise horizontally from one side wall  60  to the other. The rack  94  lies immediately below the latch door  88  in the back end wall  62  and above the port  70  in the one side wall  60 . The rack  94  supports media  96  consisting of discrete elements, which may be spherical or some other configuration and are formed from a substance capable of withstanding the temperature of exhaust gases leaving the furnace enclosure  2  and passing into the media box  22  at the burner throat  34 . Such media  96  may comprise, for example, ceramic alumina spheres of about one inch diameter. These exhaust gases pass through the media  96  and heat the media  96 , thus elevating the temperature of the media  96  to enable the media  96  to serve as a heat sink. When the furnace cycle reverses, combustion air enters the media box  22  at the lateral port  70  and flows through the media  96  to extract heat from them. As a consequence, the combustion air undergoes an increase in temperature, so that it enters the burner  20  at an elevated temperature. This renders the combustion in the burner  20  more efficient. 
         [0034]    However, in flowing through the furnace enclosure  2 , the hot exhaust gases pick up contaminants such as salts and metal oxides, including aluminum oxides and salts, from the dross that floats over the molten metal in the hearth. When the hot exhaust gases flow from the furnace enclosure  2  in the opposite direction into the media box  22  while the burner  20  is shut down, the contaminants picked up by the hot exhaust gases deposit on the media  96 . As a consequence, from time to time the media box  22  needs to be detached from the burner assembly  10  and the lateral duct  12  so that the media  96  within it can be cleaned. 
         [0035]    When using the present invention, this detachment is a quick and simple procedure. To this end, a lift truck B ( FIGS. 5-7 ) having a fork  100  that can be maneuvered upwardly and downwardly is fitted at the very front of its fork  100  with an attachment tool  102  that is capable of engaging the bracket  90  at the back end of the media box  22  from beneath such that the truck B can exert an upwardly directed force on the bracket  90  as well as a horizontal force along the direction of the rails  26 . Indeed, the truck B is maneuvered to bring the attachment tool  102  beneath the bracket  90  on the media box  22  ( FIG. 5 ). Thereupon, the fork  100  is elevated while the truck B itself remains stationary ( FIG. 6 ). The upwardly directed force tilts the media box  22  about the axis X of the trunnions  68 , causing the front end of the media box  22  to dip downwardly and its back end to rise. Thereupon the pocket  82  at the front of the box  22  withdraws from the burner throat  34 . Simultaneously, the oblique flange  72  on the port  70  lifts off the oblique flange  40  in the lateral duct  12  ( FIG. 7 ). The operator of the lift truck B then reverses the truck B to pull the media box  22  away from the burner assembly  10  and lateral duct  12 . 
         [0036]    The box  22  moves on the carriage  24  which follows the rails  26  away from burner throat  34  until the box  22  is positioned such that it will not contact the burner throat  34  when the box  22  is allowed to rotate within the carriage  24  to its point of rest with the bracket  90  pressed against the ground below the box  22 . The box  22  may then be raised and removed from the carriage  24 . The operator can then deliver the media box  22  to a location where the media  96  may be removed from it. This may, for example, involve removing the attachment tool  102  from the fork  100  of the lift truck B and inserting the tines of the fork  100  into the fork lift rails  78  of the media box  22 . Alternately, the lid  66  may be removed to gain access to the media  96 . 
         [0037]    Once the media  96  are cleaned and replaced in the media box  22 , the truck operator maneuvers the truck B so that the box  22  is placed atop the carriage  24  with the trunnions  68  resting in the cradles  56  in the side walls  54  of the carriage  24 , where the carriage  24  has remained positioned atop the rails  26 . The operator of the truck B then places the attachment tool  102  on the fork  100  of the truck B and engages tool  102  with the bracket  90  on the back end of the media box  22 . An upwardly directed force applied to the bracket  90  tilts the box  22  on the carriage  24 , lowering the pocket  82  in its vertical port  80  and elevating the lateral port  70  on its one side wall  60  ( FIG. 7 ). The operator moves the truck, and thereby the carriage  24 , forwardly toward the furnace enclosure  2  until the forward wheels  52  of the carriage  24  abut against the stops  58  at the ends of the rails  26  ( FIG. 6 ). The operator then lowers the fork  100  and, by reason of the displacement of its center of gravity from the trunnions  68 , the media box  22  tilts back to a horizontal orientation in which it is restrained by the flange  36  on the burner throat  34  ( FIG. 5 ). The flange  36  seats in the pocket  82  of the vertical port  80 , effecting a barrier with the seal  84  in that pocket  82 . The seal  74  in the oblique flange  72  of the lateral port  70  likewise seats against the oblique flange  40  at the end of the lateral duct  12  ( FIG. 4 ). 
         [0038]    The construction of the media box  22  and its placement at the end of the furnace enclosure  2  on the carriage  24  not only facilitates rapid removal of the media box  22 , but also the actual removal of contaminants from the media  96 . In this regard, once the media box  22  is separated from the burner throat  34  and the lateral duct  12 , and is withdrawn from those furnace components by the truck B, the truck operator engages the fork  100  of the truck B with the fork lift rails  78  along the side walls  60  of the media box and delivers the media box  22  to a media cleaning station C ( FIGS. 8-10 ). The station C includes a frame  110  that has side walls  112  that are spaced apart sufficiently to enable the media box  22  to freely fit between them. Moreover, the side walls  112  at their upper ends have cradles  114  that are capable of receiving the trunnions  68  on the media box  22  when the media box  22  is positioned between the side walls  112 . This arrangement resembles the carriage  24 , except that the side walls  112  are higher, and the frame  110  rests in a fixed position. The frame  110  supports a washing basket  116  that is offset from the side walls  112 , yet aligned with the space between them. The washing basket  120  has porous walls, preferably formed from a grid-like material having openings smaller than the individual elements of the media  96 . 
         [0039]    To remove contaminants from the media  96 , the truck operator raises the media box  22  to a position in which its trunnions  68  are above the cradles  114  of the cleaning station C and the latch door  88  on the back end wall  62  is above the washing basket  120 . The operator then lowers the media box  22  until its trunnions  68  are received in the cradles  114  on the side walls  112  and the box  22  is supported by the side walls  112  ( FIG. 8 ). Owing to the displacement of the center of gravity for the media box  22  from the trunnions  68 , the media box  22  tilts downwardly toward the basket  120  once free of the fork  100  of the truck B ( FIG. 9 ). Thereupon, the latch door  88  in the back end wall  62  of the media box  22  is removed, and the media  96  are allowed to tumble out of the box  22  into the washing basket  120 . While in the washing basket  120 , the media  96  are subjected to a cleaning process, such as for example a stream of water, that removes the contaminants deposited on media  96 . 
         [0040]    Once the contaminants are removed, the media  96  are returned to the media box  22  where the media  96  are supported on the porous rack  94 . Thereupon, the media box  22  is moved to the carriage  24  and the carriage  24  is maneuvered to bring the pocket  82  of the box  22  beneath and in pressed contact with the burner throat  34 , and to simultaneously align and interconnect the port  70  with the lateral duct  12 . 
         [0041]    In lieu of the media  96  which takes the form of a multitude of discrete elements organized randomly on the rack  94 , the high temperature heat sink in the media box  22  may take other alternate forms, such as the form of a solid block that is porous. Indeed, the block may be oriented vertically so that the gases flow horizontally through it. 
         [0042]    While we have described in the detailed description different configurations that may be encompassed within the disclosed embodiments of this invention, numerous other alternative configurations, that would now be apparent to one of ordinary skill in the art, may be designed and constructed within the bounds of my invention as set forth in the claims. Moreover, the above-described novel burner assembly  10  of the present invention can be arranged in a number of other and related varieties of configurations without expanding beyond the scope of my invention as set forth in the claims. 
         [0043]    For example, the present invention is not limited to a single or even two sets of assemblies  10 , but may include multiple sets of interchangeable media boxes  22  and carriages  24 . Additionally, each of the components of the assembly  10  may be of varying sizes and shapes, so long as the configuration of each component, when combined in the assembly  10 , allows the assembly  10  to have the unique features and attributes as described in this disclosure. Further, the assembly  10  may be configured to allow the media box  22  to releasably attach to a single port or duct (such as at  34  and  12 ), or multiple such ports or ducts as may be desired or necessary for the proper operation of the furnace system. 
         [0044]    Of course, the carriage  24  may be configured to be tilted and/or withdrawn from the furnace by a variety of other methods other than by a lift truck B. For example, the carriage  24  my incorporate a motor or other such self-contained locomotion apparatus. Alternatively, dissociated pistons, pulley systems, or other such devices may alternately be used to tilt and/or move the carriage  24 . 
         [0045]    Further, depending on the configuration of the furnace and its burners and combustion gas ducts, the media box  22  may be configured to tilt or rotate forward, backward, or from side to side to engage with and disengage from such burners and ducts. In addition, it is contemplated that the operation of the assembly  10  could be automated, such as with a computer control system. 
         [0046]    Additional variations or modifications to the configuration of the novel heater system media bed float system  10  of the present invention may occur to those skilled in the art upon reviewing the subject matter of this invention. Such variations, if within the spirit of this disclosure, are intended to be encompassed within the scope of this invention. The description of the embodiments as set forth herein, and as shown in the drawings, is provided for illustrative purposes only and, unless otherwise expressly set forth, is not intended to limit the scope of the claims, which set forth the metes and bounds of our invention.