Abstract:
A shield for a refractory structure that houses refractory bricks. The refractory bricks are assembled with respect to each other to form a refractory wall, roof or another refractory structure. A hanger can be used to suspend or mount at least one refractory brick. In order to extend the service life of the hanger, a shield can cover at least a portion of the hanger, such as a hanger rod, to prevent dust particles from accumulating on the rod or another hanger element. Reducing or eliminating dust particles, particularly metal dust particles, can extend the service life of hanger components and can also reduce costs associated with maintenance and repair of refractory structures, particularly within industrial furnaces.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    This invention relates to a dust shield for protecting and enhancing the life of hanger structures, particularly hangers used to suspend refractory materials in a high-temperature furnace. 
         [0003]    1. Discussion of Related Art 
         [0004]    Many industrial furnaces have a suspended roof construction for supporting refractory bricks that form a wall structure having a hot side exposed to relatively high temperatures within an industrial furnace. The opposite side or cold side of the suspended roof construction typically has structural members for supporting the roof construction or the wall. 
         [0005]    Hanger rods are typically secured or connected to one or more refractory bricks. An opposite end portion of the hanger rod can be connected or secured to a structural member, for supporting or suspending the refractory bricks. Conventional hanger rods have many different sizes, shapes and configurations. 
         [0006]    In industrial facilities that manufacture metals, such as copper or lead, the process produces undesirable metal dust or other forms of dust. During production and operation of the furnace, the metal dust accumulates on the suspended roof construction. The metal dust also collects on the hanger rods. Maintenance is often necessary to remove the accumulated dust particles from the hanger rods, to clean the metal rods. 
         [0007]    When the metal dust accumulates on the hanger rod or other hanger structure, a coating of the metal dust can act as an insulator for the hanger rod, which prevents the rod from releasing heat for cooling purposes. Also, some metal dusts or other forms of dusts have a corrosive effect on the hanger rods. The overheating and/or the corrosive activity can cause the hanger rod to fail, often before the full service life of the refractory brick which the hanger rod supports. 
         [0008]    Upon failure, maintenance procedures are required to remove the damaged hanger rod and replace it with a new hanger rod and refractory brick. Damaged hanger rods are costly to repair and can be dangerous, particularly if the wall or roof structure fails and damages the industrial furnace. 
         [0009]    There is an apparent need to reduce or eliminate the overheating and/or the corrosive degrading of hanger rods, particularly those used to suspend refractory bricks in an industrial furnace. Reducing or eliminating the need to replace hanger rods can save significant maintenance costs and can also enhance the safety associated with operating the industrial furnace by reducing or eliminating hanger rod failures. 
       SUMMARY OF THE INVENTION 
       [0010]    Dust shields, according to different embodiments of this invention, can be used to cover at least a portion of a hanger structure, such as a hanger rod. The dust shield can be made of any suitable material that resists heat and provides a relatively long service life. The dust shield according to this invention can have any suitable outer surface that prevents dust, particularly metal dust, from accumulating on the outside surface of the metal hangers. 
         [0011]    Different suitable materials for the shield, particularly the outside surface, can have a relatively low coefficient of friction so that the dust particles slide off of or move away from the outside surface of the dust shield. 
         [0012]    The dust shield can also be angled or otherwise shaped or configured to prevent or reduce dust accumulation on the outside surface of the shield. A dust shield according to this invention can have many different sizes and/or shapes, depending upon the particular design or layout of the hanger and other structural members. 
         [0013]    In some embodiments of this invention, the dust shield covers at least a portion of the hanger rod. In other embodiments of this invention, the dust shield can cover all or any significant portion of the hanger rod or other hanger structure. 
         [0014]    Maintenance costs can be significantly reduced by protecting or covering the hanger to reduce or eliminate dust buildup on at least a portion of the hanger. In some suspended roof constructions according to this invention, maintenance and safety aspects can be enhanced by maximizing the quantity or size of the hanger structure that is covered by the dust shield. 
         [0015]    Dust shield according to this invention can be manufactured from metal and/or any other suitable non-metal material or material composite. In some embodiments of this invention, the dust shield is constructed from a flat material or a sheet material and forms a hollow interior. In other embodiments of this invention, the heat shield can be constructed of one or more solid or filled segments of a metal or a non-metal material. Depending upon the particular environment of the industrial furnace, the heat shield can be made from a fiber material having relatively high heat-resistant properties and/or corrosive-resistant properties. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0016]    This invention is explained in view of exemplary embodiments, making reference to the drawings, wherein: 
           [0017]      FIG. 1  is a perspective view of a conventional hanger structure for one or more refractory bricks; 
           [0018]      FIG. 2  is a perspective view of a dust shield covering at least a portion of a conventional hanger, according to one embodiment of this invention; 
           [0019]      FIG. 3  is a perspective view of a dust shield having a conical frustum, according to one embodiment of this invention; 
           [0020]      FIG. 4  is a top view showing a pattern, in two dimensions, that is used to form a conical frustum shaped dust shield, such as shown in  FIG. 3 ; 
           [0021]      FIG. 5  is a perspective view of a dust shield having a pyramidal frustum, according to one embodiment of this invention; and 
           [0022]      FIG. 6  is a top view showing a pattern in two dimensions, that is used to form a pyramidal frustum shaped dust shield, as shown in  FIG. 5 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0023]    Hangers, including hanger rods, provide a structural connection between a suspended roof construction of refractory materials and existing or required structural members. For example, Merkle, U.S. Pat. No. 4,424,756 teaches a suspended roof construction for an industrial furnace. Merkle, Jr., U.S. Pat. No. 4,073,243, teaches a hanger assembly for suspending at least one refractory brick used in a high temperature industrial furnace roof construction. The entire teachings of each of U.S. Pat. No. 4,424,756 and U.S. Pat. No. 4,073,243 are incorporated by reference into and are made a part of this specification. 
         [0024]      FIG. 1  shows refractory structure  20  as conventionally known. Plate  22  may or may not be used to encase or house one or more refractory bricks  25 . As shown in  FIG. 1 , plate  22  covers at least a portion of a periphery of two adjacently positioned refractory bricks  25 . Any other suitable encasement or housing structure can be used to support one or more refractory bricks  25 . In other embodiments of this invention, refractory bricks  25  have no encasement. 
         [0025]    Also as shown in  FIG. 1 , rod  32  is used to connect or suspend refractory brick  25  from support structure  34 . Support structure  34  can comprise any existing support member and/or any support member furnished with refractory structure  20  or another suitable suspended refractory wall. 
         [0026]    According to this invention, refractory structure  20  can comprise a plurality of refractory bricks  25 . Refractory brick  25  of this invention can comprise any other suitable refractory shape, refractory block, refractory structure or any other suitable structure of high-temperature resistant materials, such as those used in an industrial furnace or a commercial furnace operating at relatively high temperature ranges. The sizes, designs and/or proportional dimensions of refractory brick  25  can be varied to accommodate different uses of refractory structure  20  and/or refractory brick  25 , according to this invention. Refractory brick  25  can be constructed from any suitable refractory material, such as those conventional refractory materials that can withstand relatively high temperatures. In certain embodiments of this invention, refractory brick  25  can be constructed of any suitable zircon, fireclay, silica, alumina, chromite and/or silicon carbide material. 
         [0027]    Hanger  30  can be used to suspend at least one refractory brick  25 . As shown in  FIGS. 1 and 2 , rod  32  of hanger  30  supports two refractory bricks  25 . As shown in  FIGS. 1 and 2 , plate  22  at least partially encompasses two refractory bricks  25 , such as to form an encasement, an enclosure or a housing that accommodates each refractory brick  25 . Any other suitable housing or frame can be used to mount or suspend at least one refractory brick  25 . In the embodiments shown in  FIGS. 1 and 2 , plate  22  comprises void  24 . When in a mounted or suspended position, rod  32  of hanger  30  is mounted within or passes through void  24  formed by plate  22 . U.S. Pat. 4,073,243 teaches different conventional hanger structures that can be used as hanger  30  according to this invention. Although hanger  30  can be attached directly to plate  22  or another suitable housing, as shown in  FIGS. 1 and 2 , rod  32  passes through void  24  and into a void formed by at least one refractory brick  25 . 
         [0028]    Many industrial environments, such as metal processing facilities, generate significant amounts of dust or dust particles, particularly metal dust particles such as copper particles and lead particles. If the dust particles accumulate on hanger  30 , particularly on rod  32 , because the metal dust particles act as an insulator, hanger  30  and/or rod  32  cannot adequately cool by transferring heat away from hanger  30  and/or rod  32 . 
         [0029]    As shown in  FIG. 2 , shield  40  can be used to cover at least a portion of rod  32 , for example so that dust particles do not accumulate on the portion of rod  32  that is covered by shield  40 . In certain embodiments of this invention, shield  40  can cover a significantly larger portion of rod  32  than the portion shown as covered in  FIG. 2 . 
         [0030]    Rod  32  can be of any suitable size, shape, material and/or configuration. As shown in  FIGS. 1 and 2 , rod  32  has a bend approximately at a middle section of rod  32 , and also a hook at an end which is opposite the end attached to refractory brick  25 . Hanger  30  and/or rod  32  can have any other suitable shape that accommodates an existing or a newly installed support structure  34 . Dimensions of shield  40  can be varied to cover more or less of hanger  30  and/or rod  32 . 
         [0031]    As shown in  FIGS. 2-6 , shield  40  has an external shape of or similar to a frustum. As used throughout this specification and in the claims, the term frustum is intended to relate to a cone or a pyramid shape having a tip section or portion that is truncated, including but not limited to truncated by a plane that is parallel to a base of the cone or the pyramid. For purposes of this invention and encompassed by the term frustum, the plane of truncation does not need to be parallel to the base plane, for example to prevent dust from collecting on hanger  30  and/or rod  32 . 
         [0032]    In some embodiments of this invention, the frustum formed by shield  40  is a conical frustum, such as shown in  FIGS. 3 and 4 , or in other embodiments is a pyramidal frustum, such as shown in  FIGS. 5 and 6 .  FIG. 3  shows a perspective three-dimensional view of shield  40  formed as a conical frustum.  FIG. 4  shows a two-dimensional layout or pattern of flat material that can be cut and bent or shaped to form the three-dimensional shield  40  as shown in  FIG. 3 . Likewise,  FIG. 6  shows a two-dimensional layout or pattern of the pyramidal frustum shape of the three-dimensional shield  40  as shown in  FIG. 5 . 
         [0033]    Shield  40  can have any suitable outer surface  41  that prevents dust particles from collecting on outer surface  41 . In some embodiments of this invention, outer surface  41  can have a relatively low coefficient of friction, so that dust particles cannot adhere to outer surface  41 . Outer surface  41  can be positioned at any suitable angle or angle of repose, for example with respect to a longitudinal axis passing through shield  40 , such as in the vertical direction shown in  FIGS. 3 and 5 , that prevents dust particles from collecting on outer surface  41 . 
         [0034]    As shown in  FIG. 3 , a cross section of shield  40  taken in a direction generally perpendicular to the longitudinal axis generally forms a circle. In a similar perpendicular direction, shield  40  as shown in  FIG. 5  has a generally square cross section. A similar cross section of shield  40  according to other embodiments of this invention can have any other suitable non-circular or polygonal shape that helps prevent dust particles from collection on outer surface  41 . 
         [0035]    Shield  40  can be manufactured, formed, constructed or manufactured from any suitable sheet material, filler material, solid material, such as any suitable metal, any suitable non-metal and/or any suitable composite structure or material. 
         [0036]    In certain embodiments of this invention, shield  40  forms a hollow space through which rod  32  passes or is mounted. In other embodiments according to this invention, shield  40  can be at least partially or entirely constructed of a filler material or a solid material, such as a fibrous material or a porous material. Any filler or solid material can have a bore or other void that accommodates rod  32  or any other element of hanger  30  that requires protection. 
         [0037]    As shown in  FIGS. 2 ,  3  and  5 , shield  40  comprises opening  42  through which rod  32  passes or is mounted. Preferably but not necessarily, an outer surface of rod  32  forms a relatively tight fit with respect to opening  42 , for example so that no or few dust particles pass through opening  42  and onto rod  32  and/or any other element of hanger  30  which requires dust protection. 
         [0038]      FIG. 2  shows bottom surface  44  of shield  40  contacting upper surface  23  of plate  22 . In a similar fashion, such as for preventing dust particles from entering the space formed by shield  40 , bottom surface  44  can form a relatively tight fit with respect to upper surface  23  of plate  22 . As shown in  FIG. 2 , plate  22  is positioned between shield  40  and at least one refractory brick  25 . 
         [0039]    As shown in  FIGS. 4 and 6 , shield  40  in a two-dimensional state has free ends  43  that can be welded, connected, secured or otherwise attached with respect to each other to form the shape shown in  FIGS. 3 and 5 . Shield  40  can also be constructed as one integrated piece. 
         [0040]    In other embodiments of this invention, shield  40  can extend above or beyond the length of rod  32 . In such embodiments, shield  40  has a pointed tip structure and is not truncated, so that dust particles do not form on an upper surface of shield  40 . 
         [0041]    While in the foregoing specification this invention has been described in relation to certain preferred embodiments thereof, and many details have been set forth for purpose of illustration, it will be apparent to those skilled in the art that the invention is susceptible to additional embodiments and that certain of the details described herein can be varied considerably without departing from the basic principles of the invention.