Abstract:
A burner for melting material in a furnace includes an elongated member having a first end with a heat source, a second end with an exhaust, and a combustion chamber disposed in the elongated member interconnecting the first and second ends, a portion of the elongated member between the first and second ends in contact with the material to be melted. A method for melting the material is also provided.

Description:
[0001]    The present inventive embodiments relate to burners used to melt for example metal or alloy compositions. 
         [0002]    Oxy-fuel burners are typically installed in a furnace or a melting furnace in a “direct fired” manner. That is, such burners are typically disposed such that there is no physical barrier between the burner flame and/or products of burner combustion, with the material to be heated or melted. 
         [0003]    Radiant tube burners are considered “indirect fired” burners, that is they consist of an air-fuel burner having a flame and products of combustion which are confined to an interior of the tube, prior to being exhausted. The tube is positioned in the furnace such that 1) the flame and products of combustion heat the tube from the tube interior, 2) the tube is positioned in the furnace, but not in contact with the material to be heated or melted, and 3) the tube&#39;s outer surfaces, heated from the inside, radiate heat to the furnace combustion chamber atmosphere to heat the material to be melted. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0004]    For a more complete understanding of the present embodiments, reference may be had to the following detailed description taken in conjunction with the drawings, of which: 
           [0005]      FIG. 1  shows an elevation view of an oxy-fuel burner of the present embodiment; 
           [0006]      FIG. 2  shows an elevation view of an oxy-fuel burner of another embodiment; 
           [0007]      FIG. 3  shows an elevation view of an oxy-fuel burner of still another embodiment; 
           [0008]      FIG. 4  shows a plan view along line IV-IV of the embodiment of  FIG. 3 ; 
           [0009]      FIG. 5  shows a cross-sectional view of a portion of the oxy-fuel burner of the present embodiments; 
           [0010]      FIG. 6  shows a melter embodiment using a plurality of the oxy-fuel burners of for example  FIG. 2 ; 
           [0011]      FIG. 7  shows an elevation view of an oxy-fuel burner of still another embodiment; 
           [0012]      FIG. 8  shows a plan view along line VIII-VIII of the embodiment of  FIG. 7 ; and 
           [0013]      FIG. 9  shows an elevation view of an oxy-fuel burner of still another embodiment. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0014]    The present embodiments provide for improved heat transfer with respect to the products to be melted. 
         [0015]    The embodiments of  FIGS. 1-6  find use for example in reverberatory furnaces for aluminum and/or copper melting. The burner embodiments are disposed such that a substantial portion of such embodiments are submerged in the molten or semi-molten metal, while products of combustion of the burner embodiments are exhausted so as not to contact the melt. 
         [0016]    Referring to  FIGS. 1-5 , a melting furnace shown generally at  10  includes a side wall  12  constructed to provide a combustion chamber  14  therein in which a material to be melted is disposed which will be brought to a molten consistency as shown generally at  16  as a molten or semi-molten bath or melt. 
         [0017]    The oxy-fuel burner or burner  18  is constructed in a tubular shape having for example a circular cross section, with an inlet shown generally at  22  and an outlet or exhaust shown generally at  24 . An oxygen feed  26  and a fuel feed  28  are connected to a burner portion  30  for providing a combustion flame  32  at an interior  34  of the burner tube  18 . The interior  34  of the burner tube  18  is hollow, wherein the combustion flame  32  provides for the necessary heat to be transferred through the burner tube  18  to contact and heat the molten bath  16 . That portion of the interior  34  exposed only to the combustion atmosphere  14 , and not the melt  16 , provides for heating of the combustion atmosphere  14  to further maintain the molten consistency of the bath  16  after such material has been melted. Exhaust gases from the combustion flame  32  are exhausted through the outlet  24  as indicated by arrow  36 . The exhaust  36  may be sent to a scrubber or other capture device (neither of which is shown). 
         [0018]    A material from which the tube  18  is constructed is selected from silicon carbide or a material with similar characteristics, i.e. such material being able to withstand the characteristics of the combustion atmosphere  14  and the bath  16 . The inlet  22  and the outlet  24  may be arranged so that they are parallel and in a common plane. 
         [0019]    As shown in the drawings, including  FIG. 6 , that portion of the burner tube  18  in direct contact with the melt  16  provides the heat transfer effect for melting and maintaining the molten aspect of the bath  16 . Approximately 20% to 80% of the tube  18  may be submerged in the bath  16 . The burner  18  may be arranged in the furnace  10  up to 90° from the vertical or in other words up to 90% from a surface of the melt  16 . Such a range of disposition is shown for example when comparing  FIG. 2  and  FIG. 3 . 
         [0020]    Heating of the tube interior by all the embodiments of  FIGS. 1-6  is by convection and radiation. 
         [0021]    As shown in  FIG. 5 , for example, the quotient (Q) of radiation and the quotient of convection is added to the quotient of conduction to facilitate the melting which occurs in, for example, an aluminum (Al) bath  16 . The oxy-fuel flame that is created at an interior of the burner tube  18  transfers energy to the tube by convection and radiation. In this case, the heated exhaust gases from the flame, made up of carbon dioxide and water vapor, circulate inside the tube and in turn transfer energy to the tube&#39;s inside surface. Radiation, in this case, the relatively bright oxy-fuel flame created inside the tube, transfers energy in the form of heat via wavelengths of light. Once energy (in the form of heat) is transferred to the interior surface of the tube, the energy is then transferred through the tube wall by conduction into the bath  16 . Once the outside surface of the tube is heated, energy is then further transferred to the bath again by conduction. The products of combustion are exhausted from the tube without coming in contact with the product to be melted. 
         [0022]    In  FIG. 6 , the burners of for example those shown in  FIG. 1  or  2 , are mounted in a furnace for operation. The furnace  10  includes the side wall  12  constructed to provide the combustion chamber  14  in which is charged a metal or alloy material to be melted into a bath  16 . The burners  18  will be employed to provide the melting of the metallic charge material. As shown in  FIG. 6 , the portion of the tube  18  shown generally at  38  lies below the surface of the molten or semi-molten bath  16 . 
         [0023]    The side wall  12  is constructed with a top  40  and a bottom  42 . The top  40  and the bottom  42  are joined together with stepped side walls  44 ,  46 . The burners  18  selected for use in the embodiment of  FIG. 6  have the inlet portion  22  disposed at the corresponding stepped side walls  44 , 46 , while the outlet portion  24  containing for the exhaust  36  is provided for at the top  40 . In this manner of construction, the exhaust  36  may be released to a scrubber or other capture device (not shown) away and elevated from the inlet  22  of the tubular burner  18 . Neither exhaust gases nor particulate matter are introduced into the chamber  14  or the bath  16 . 
         [0024]    The heat transfer via an oxy-fuel burner in a radiant tube submerged into the metal to be melted, is more efficient than the conventional method wherein a direct fired air-fuel burner is positioned in a furnace such that the flame is developed above the metal to be heated. The improved heat transfer provided by the burner embodiments results in more efficient and economic fuel consumption. In addition, the products of combustion at the interior  34  of the tubular burner  18  do not contact the molten metal in the bath  16 , thereby reducing if not eliminating oxidation of the composition being melted in the bath  16 . Further, because combustion occurs in the tube, and not in the chamber  14  (head space) above the bath  16 , this translates into being able to use a smaller melter or furnace  10 , thereby reducing the initial capital expense and ongoing operating expense. In addition, because the combustion flame  32  is not provided in the combustion chamber  14  of the furnace, the combustion chamber  14  or head space can be at a reduced or minimum height which correspondingly translates into reduced air infiltration to the furnace and reduced oxidation of, for example, aluminum if such metal is being processed in the furnace. 
         [0025]    Since the products of combustion from the oxy-fuel flame are not in contact with the material being melted, an inert gas can be provided through injection port  52  into the chamber  14  above the molten metal (the gas being confined to the chamber  14  by the walls of the furnace), as shown by arrows  54 , to protect the material from oxidation caused by ambient air possibly leaking into the furnace through a furnace door  50  or other openings in the furnace structure. The inerting gas  54  can be selected from nitrogen, argon or similar inert gas. The door  50  can include a transparent portion of heat resistant glass for observing the combustion chamber, material being melted, and the furnace operation. Injecting the inert gas into the chamber  14  would not be practical or effective in a conventional furnace because the injected nitrogen would mix with the products of combustion from the flame, i.e., CO 2 , H 2 O and N 2  in some cases. 
         [0026]    In  FIG. 7  and  FIG. 8 , the tubular burner  18  is constructed in an “L” shape. The embodiment of  FIG. 9  shows the tubular burner  18  constructed in a “W” shape. In both the embodiments of  FIGS. 7-9 , a portion of a respective one of the tubular burners  18  is disposed to contact the particulate material to be melted, or submerged in the bath  16  for heating thereof, as may be done with other of the embodiments herein. The tubular member  18  can be formed in a myriad of different shapes, a portion of which is submerged into the bath  16 . 
         [0027]    In addition, the embodiments of  FIGS. 7-9  can be arranged individually or in combination with each other in a furnace  10  as shown in  FIG. 6 . 
         [0028]    The burner  18  is fabricated from material that can withstand thermal and mechanical shock, chemical reaction (fluxing) and be able to absorb and transfer heat readily and efficiently. The material from which a sidewall of the burner  18  is fabricated will not deform or be structurally compromised when in contact with the molten material in the bath  16 . 
         [0029]    A method is also provided from the embodiments of  FIGS. 1-9  for melting particulate material in a furnace, the method including providing a combustion flame in a hollow elongated member, heating the elongated member with the combustion flame, disposing at least a portion of the elongated member in the particulate material, and heating the particulate material by conduction of the heat from the elongated member for melting said particulate material. 
         [0030]    Reduced specific energy consumption will also be realized by the embodiments of  FIGS. 1-9 , in view of the reduction of energy consumed per unit weight of metal, such as aluminum, melted. Reduced melting times result in increased productivity and lower production costs. 
         [0031]    There is also realized reduced oxidized material (‘dross’ is the term used within the aluminum industry, the copper industry uses ‘slag’, in both cases it&#39;s metal originally charged in its pure state, but then oxidized in the melting process) formation as a result of no contact between the exhaust  36  and the product being melted in the bath  16 . 
         [0032]    The present embodiments can be used with copper, tin and magnesium furnaces or melters. 
         [0033]    It will be understood that the embodiments described herein are merely exemplary, and that a person skilled in the art may make many variations and modifications without departing from the spirit and scope of the invention. All such variations and modifications are intended to be included within the scope of the invention as described and claimed herein. It should be understood that embodiments described above are not only in the alternative, but may also be combined.