Abstract:
A method and apparatus for introducing oxygen enriched air into a furnace includes injecting oxygen to a combustion chamber of the furnace; and entraining air into the oxygen during the injecting. If the furnace is a cross-fired regenerative furnace, the method and apparatus for introducing oxygen enriched air can be mounted to at least one regenerator for the furnace.

Description:
BACKGROUND 
       [0001]    The present embodiments relate to apparatus and methods for injecting oxygen into a furnace. 
         [0002]    Regenerative glass melting furnaces use regenerators—high temperature heat exchangers—which are essentially large assemblies of bricks and/or high temperature refractories. The regenerators can become blocked after many years of use or from perhaps structural failure of the refractory, which thus starves the furnace of air that the regenerator is providing. 
         [0003]    In order to overcome the blockage of the regenerators, it is known to install by-pass flues for the blocked portion of the regenerators. Unfortunately, such flues result in lower air pre-heat temperatures, which is less efficient and results in increased gas use and accordingly, more air is needed for the furnace, which defeats the purpose of the by-pass flue. 
         [0004]    It is also been known to enrich the furnace with oxygen either upstream, as a single injection point, or downstream, with a plurality of injection points through reversal valves. However, such an application is limited in the percentage of oxygen that can be used. Such oxygen still has to pass through the blockage in the regenerator and therefore, the problem is not cured. 
         [0005]    Lancing has been found to be a more efficient method to provide oxygen to the furnace. However, when using large cross-fired furnaces, the installation for the lances can be quite significant, requiring construction of the furnace to accommodate the lances. Such construction may provide undesirable furnace conditions, wherein unwanted foam generation occurs in the glass melt. 
         [0006]    Finally, there may be limits on the amount of compressed oxygen available at the site of the furnace. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0007]    For a more complete understanding of the present inventive embodiments, reference may be had to the following description of the embodiments taken in conjunction with the drawing figures, of which: 
           [0008]      FIG. 1  shows a top plan view of a known sidewall regenerative furnace firing without oxygen injection; 
           [0009]      FIG. 2  shows a cross-sectional side view of an oxygen injector embodiment of the present invention for use with a furnace; 
           [0010]      FIG. 3  shows an end view in cross-section of the regenerative furnace taken along line  3 - 3  in  FIG. 1  with positions for installation of the oxygen injector apparatus of  FIG. 2 ; 
           [0011]      FIGS. 4-7  show top plan views of the regenerative furnace having one or a plurality of the oxygen injector embodiments mounted for use with a respective one of the regenerative furnace; 
           [0012]      FIG. 8  shows a cross-sectional side view of the oxygen injector embodiment of  FIG. 1  for being mounted to a wall of a furnace regenerator; 
           [0013]      FIGS. 9-12  show cross-sectional side views of alternative embodiments of the oxygen injector apparatus of the present invention; and 
           [0014]      FIG. 13  shows a top plan view of a furnace having at least one oxygen injector apparatus embodiment for use therewith. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0015]    Referring to  FIG. 1 , a known furnace is shown generally at  10 . The furnace can be used for heating applications to melt for example glass, steel, scrap metal or non-ferrous materials. By way of example only, the furnace  10  is a glass melting furnace to which the oxygen injector apparatus embodiment of the present invention can be mounted for operation. 
         [0016]    The furnace includes at one end at least one and in some applications a pair of chargers  12  through which glass ingredients or other materials are introduced into the furnace for melting. The chargers  12  are located at an upstream end of the furnace  10 , while a downstream end of the furnace includes a throat section  14  and a distribution section  16 . The distribution section  16  may include a forehearth or other structure for distribution of the glass melt. 
         [0017]    Mounted to each side of the furnace  10  is a regenerator  18 , 20 , respectively. Therefore, in the combustion industry, the furnace  10  would be referred to as a cross-fired regenerative furnace. With respect to  FIG. 1  and this description, the regenerator  18  will be referred to as the left-hand side regenerator, while the regenerator  20  will be referred to as the right-hand side regenerator. The regenerator  18  includes corresponding end walls  22 , 24 , a top wall  23  or roof, and a side wall  26 . A plurality of ports  28  of the regenerator  18  are in communication with the furnace  10 . 
         [0018]    The regenerator  20  also includes end walls  30 , 32 , a top wall  31  or roof, and a side wall  34 . A plurality of ports  36  of the regenerator  20  are in communication with the furnace  10 . The sidewalls  26 , 34  are also known in the industry as the “target walls”. 
         [0019]    A gaseous flow of air through the ports  28 , 36  is shown by arrows  38 , 40  respectively. 
         [0020]    Although not shown in  FIG. 1 , but later shown and discussed in more detail with respect to  FIG. 3 , a plurality of heat recovery bricks, also known as checker bricks, are disposed in each one of the regenerators  18 , 20  such that each of the airflows  38 , 40  flows over and contacts a corresponding plurality of the heat recovery bricks. When firing, for example, from left to right in the furnace (from the regenerator  18  to the regenerator  20 ) combustion air is heated at the regenerator  18  and the heat recovered at the regenerator  20 . This process is reversed when firing from right to left in the furnace  10 . 
         [0021]    In known cross-fired regenerative furnaces such as that shown generally at  10 , any oxygen lancing would be directly into the furnace  10 , but also be subjected to the disadvantages above with respect to such known furnaces. Operation of the regenerative furnace  10  as shown in  FIG. 1  is therefore already known. 
         [0022]    Referring to  FIG. 2 , an embodiment of an oxygen injector apparatus  42  of the present invention is shown for use with the known regenerative furnace  10 . The injector  42  includes an injector body portion  44  having a space  46  or passageway therein in which to receive an oxygen lance  48  or pipe. The oxygen lance  48  includes an internal passageway  49 . A distal end of the body portion  44  is provided with an injector nozzle  50 . A proximal end of the body portion  44  is provided with a seal  52  or gasket. An inlet duct  54  is in fluid communication with the space  46  of the body portion  44  so that entrained air indicated by arrow  56  can be introduced into the space  46  to be mixed with an oxygen stream represented by the arrow  58  flowing through the passageway  49  to be introduced into the space  46  by the oxygen lance  48 . That is, the injection of the oxygen stream  58  through the oxygen lance  48  entrains air  56  through the inlet duct  54  to be mixed in the space  46  with the oxygen stream. 
         [0023]    The oxygen lance  48  is movably positionable and adjustable with respect to the nozzle  50  which will, in effect, control the flow of the entrained air  56  through the inlet duct  54  into the space  46 . Arrows  60  represent movement of the oxygen lance  48  in the space  46 . The lance  48  is movable along its longitudinal axis substantially parallel to a longitudinal axis of the body portion  44  extending along the space  46 . All of the elements of the oxygen injector apparatus  42  are constructed of metal, except for the seal  52 . In most applications, the entrained air  56  will be provided, for example injected, into the oxygen stream  58  before entering into the furnace  10  or the regenerators  18 , 20 . 
         [0024]    The oxygen injector apparatus  42  can be mounted to the regenerator in one or a plurality of positions as shown in  FIG. 3 . For example, the oxygen injector apparatus  42  can be mounted to the end wall  22  or the side/target wall  26  of the regenerator  18 . Such location and mounting of the oxygen injector apparatus  42  can be through an existing peep site  62  of the regenerator  18 . The oxygen injector apparatus  42  can also be mounted in a similar manner to the regenerator  20 . The heat recovery bricks  64 , 66  or checker bricks discussed above with reference to  FIG. 1 , are shown in  FIG. 3  as they would be disposed in respective ones of the regenerators  18 , 20 . It should be understood that certain regenerators may have their end walls and/or side walls bored-out or originally manufactured to receive the oxygen injector apparatus  42 , instead of mounting such apparatus in all of the peep sites  62 . Operators of such furnaces will not want to plug all the peep sites with injector apparatus because it is important to be able to view an interior of the furnace  10  during combustion operations. 
         [0025]    In  FIGS. 4-6 , the oxygen injector apparatus  42  is shown mounted at the end walls  22 , 24  and  30 , 32 , including being mounted at the side walls  26 , 34 . Referring to  FIG. 4 , arrows  68  show the gas flow being injected from the regenerator  18  that has the injector apparatus  42  mounted thereto. As will be discussed below, the oxygen injector apparatus  42  is mounted so that a discharge orifice discussed further herein is in communication with a space in the regenerator  18  (and  20 ) above the heat recovery bricks  64 , 66 . As shown in  FIG. 4 , the gas flow  68  proceeds from the regenerator  18  into the furnace  10  to the regenerator  34  where it is exhausted or recycled. In  FIG. 5 , the oxygen injector apparatus  42  are mounted at the opposite regenerator  20  (the right-hand side regenerator) such that a gas flow  70  is from the regenerator  20  into the furnace  10  to the regenerator  18  where it is exhausted therefrom or recycled. With both embodiments of  FIGS. 4 and 5 , the oxygen injector apparatus  42  are mounted in the end walls of the respective regenerators  18 , 20 . 
         [0026]    In  FIG. 6 , at least one, and for many applications a plurality of oxygen injector apparatus  42  are mounted in the side/target wall  26  of the regenerator  18 . Accordingly, the gas flow represented by the arrow  72  shows the flow from the regenerator  18  into the furnace  10  and to the regenerator  20  where it is exhausted or recycled. It will be understood that the oxygen injector apparatus  42  could be mounted for use with the regenerator  20  as shown by the broken arrows  73  for said apparatus. In such manner of construction and application, the gas flow  73  would be reversed to flow from the regenerator  20  into the furnace  10  and then to the regenerator  18  where it would be exhausted or recycled. 
         [0027]    Another embodiment has the oxygen injector apparatus  42  mounted at both side walls  26 ,  34  of the regenerators  18 , 20  respectively. However, for operation of same, only one regenerator will operate to provide the gas flow from the regenerator into the furnace while the other regenerator does not have its oxygen injector apparatus activated. After a select period of time, about 20-30 minutes, the active regenerator and oxygen injector(s) are deactivated, and the opposite regenerator and oxygen injector(s) are activated. 
         [0028]    In  FIG. 7 , a still further embodiment of the regenerator is provided with the oxygen injector apparatus  42 . The previous FIGS. show that the entrained air  56  into the inlet duct  54  originated externally from the furnace  10 , the regenerators  18 , 20 , the throat section  14  and the distribution section  16  of the furnace. Accordingly, the entrained air is ambient air and is much cooler than that which is provided in the regenerators  18 , 20 . In the embodiment of  FIG. 7 , the inlet duct  54  (see  FIG. 2 ) of the oxygen injection apparatus  42  is in communication with heated air from an area or region near a forehearth  74  or the distribution section  16 . That is, the ambient air is drawn in from a region external to and proximate the furnace  10  and the regenerators  18 , 20  where the air is hot from exposure to the furnace and regenerators. The hot air is shown for example being delivered through a conduit  76  from a position near the forehearth to be provided to inlet duct  54  at the regenerator  18 , as a heated air flow  75 . It is understood that the arrangement of and coaction between the forehearth  74  and the conduit  76  could be such that the conduit is also in communication with the regenerator  20 . 
         [0029]      FIG. 8  shows in more detail how the regenerators  18 , 20  would have the oxygen injection apparatus  42  mounted thereto. The illustration of  FIG. 8  could be with reference to the end walls  22 , 24  and  30 , 32  or the sidewalls  26 , 34 . For purposes of explanation and by way of example only, the oxygen injection apparatus  42  is shown in  FIG. 8  being mounted to the side wall  26  which, in conjunction with a roof  78  or crown of the regenerator, defines a space  80  or combustion chamber in the regenerator. The side wall  26  may be constructed of an internal wall portion  82  adjacent to the heated atmosphere of the combustion chamber  80 . Adjacent to the wall  82  is an outer wall portion  84 . Insulation  86  is mounted to the outer wall portion  84 . The side wall  26  has a hole  88  extending therethrough the internal and outer wall portions  82 , 84  and the insulation  86  into which the oxygen injection apparatus  42  can be mounted. The hole  88  may be bored through the side wall  26  or alternatively, the peep site  62  of a regenerator  18 , 20  may be modified to receive the oxygen injection apparatus  42 . A discharge orifice  53  of the apparatus  42  when mounted in the hole  88  is disposed above the heat recovery bricks  64 . If the peep site  62  is used, the site is usually mounted in a block  90  in the sidewall  26 . 
         [0030]      FIG. 9  shows another embodiment of the oxygen injection apparatus  42  having a more basic construction without the injector nozzle  50  and the seal  52 . 
         [0031]    In  FIG. 10 , the oxygen injection apparatus  42  is essentially the same as that provided above in  FIG. 2 , with the addition of a swirler vane  92  or vortex element or member disposed in the space  46  to increase mixing of the entrained air  56  with the injected oxygen  58 . 
         [0032]    In  FIG. 11 , a swirler vane  94  or vortex element or member is disposed in the internal passageway  49  of the oxygen lance  48  to provide turbulence to the oxygen stream  58  to increase mixing of same with the entrained air flow  56 . 
         [0033]    Referring to  FIG. 12 , the oxygen injection apparatus  42  includes both swirler vane elements  92 , 94  in a respective one of the space  46  and the passageway  49 . Such construction provides the highest amount of turbulence to facilitate mixing the injected oxygen  48  with the entrained air flow  56 . 
         [0034]    In  FIG. 13 , the furnace  10  is shown with the oxygen injector apparatus  42  mounted in side walls  27 , 33  of the furnace or alternatively, at least one oxygen injector apparatus  42  can be mounted in a roof  35  or crown of the furnace  10 . It will be understood that any combination of the oxygen injector apparatus  42  can be mounted to the furnace through the existing side walls  27 , 33  or through the crown or through the roof  35 , or even through existing peepholes (see  FIG. 3 ) at the side walls. Similarly, the furnace  10  shown in  FIG. 13  can be constructed with the features to direct the hot ambient air  75  to the oxygen injector apparatus  42  as shown in  FIG. 7 , and to provide the same beneficial result of providing hotter air to be entrained with the oxygen for being injected into the combustion chamber of the furnace. 
         [0035]    The entrained air  56  can be provided to the oxygen stream  58  prior to the oxygen stream entering the regenerator  18 , 20  or the furnace  10 . 
         [0036]    It will be understood that the embodiments described herein are merely exemplary, and that one skilled in the art may make 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. Further, all embodiments disclosed are not necessarily in the alternative, as various embodiments of the invention may be combined to provide the desired result.