Patent Abstract:
An arrangement for protecting heat-absorptive elements in a high-temperature furnace includes a refractory member comprised of an interconnected metal structure embedded within the member and a tubular insert element capable of attaching the refractory member to the heat-absorptive element. The tubular insert has a hollow tubular body that is capable of sliding within a passageway through the embedded metal structure. The tubular insert has a rib or lip with an outer diameter larger than the passageway through the metal structure that engages the structure. When the other end of the tubular insert is connected to the heat-absorptive element, the rib holds the refractory member in place without a need to weld the tubular insert directly to the metal structure.

Full Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of U.S. Provisional Patent Application No. 60/850,692 filed Oct. 10, 2006, and entitled “Insert for Use in Securing Refractory Members to Heat-Absorptive Elements,” the contents of which are incorporated herein by reference. 
     
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    This invention relates to furnace insulation systems, and more particularly, to means for securing refractory members to a heat-absorptive element in order to better protect the element from the extreme temperatures of the furnace. 
         [0004]    2. Description of Related Art 
         [0005]    Furnaces for heating metals often operate at extremely high temperatures. Within these furnaces are metal structures that provide structural support. In order to maintain the integrity of these support structures, the structures are insulated from the extreme heat by external refractory members and cooled internally with circulating fluid. These refractory members are connected to the metal support structures in a multitude of ways so as to withstand the high temperatures, thermal shock, vibrations, and other forces to which these support structures are subjected. Because these refractory members must be routinely replaced, ease of installation is also of importance. 
         [0006]    One commonly known refractory member, disclosed in U.S. Pat. No. 4,528,672, comprises a refractory shape having an interconnected, reticulated metal mesh defined by a plurality of spirals embedded within the shape. This refractory member is connected to the heat-absorptive element through the use of an anchor pipe. The anchor pipe is a tubular insert that is inserted through the metal-mesh embedded in the refractory member and then welded to both the metal mesh and the heat-absorptive element. By securing the anchor pipe to both the metal mesh embedded within the refractory member and the heat-absorptive element, the refractory member remains connected to the heat-absorptive element. 
         [0007]    However, the anchor pipe used in this refractory system suffers from several disadvantages. First, it takes considerable time and effort to weld the metal spirals to the anchor pipe to ensure that the anchor pipe remains secure within the refractory member. Second, the anchor pipe must always be secured to the heat-absorptive element by means of welding. Third, a washer must be welded into the anchor pipe to generate a lip which allows the refractory member(s) to be bolted to the heat-absorptive element. 
         [0008]    It is therefore an object of the present invention to allow the operator the option of connecting the refractory member to the heat-absorptive element by either a bolting process or a welding process while also minimizing the steps necessary to secure a tubular insert within the refractory member. 
       SUMMARY OF THE INVENTION 
       [0009]    The present invention is directed to a protective refractory member for use in a high-temperature furnace. In one embodiment, the present invention comprises a refractory member, a reticulated metal structure embedded within the member and positioned so that there is at least one uninterrupted passageway through the metal structure and the member, a tubular insert located within the passageway wherein the tubular insert is comprised of a hollow tubular body with an outer diameter sized so that the tubular insert fits within the uninterrupted passageway, and two tubular insert ends wherein the outer diameter of the first end is larger than the outer diameter of the second end so that the second end fits within the uninterrupted passageway and the first end engages the metal structure. 
         [0010]    In one variation, the inner diameter of the second end of the tubular insert is smaller than the inner diameter of the tubular body. 
         [0011]    The refractory member of the present invention may additionally comprise a bolt, which is inserted through the tubular insert and secures the refractory member to a heat-absorptive element. Alternatively, the second end of the tubular insert can be connected to the heat-absorptive element by way of a weld. 
         [0012]    In another variation, the invention may additionally comprise a bolt which is inserted through the tubular insert and connects the refractory member to another refractory member and thereby secures both refractory members to a heat-absorptive element within the furnace. 
         [0013]    In another embodiment, the present invention comprises a first refractory member located immediately adjacent to and substantially covering one side of a heat-absorptive element and a second refractory member located immediately adjacent to and substantially covering the opposite side of the heat-absorptive element. In each of the refractory members, a reticulated metal structure is embedded therein and positioned so that there is at least one uninterrupted passageway through the structure and the refractory member. Additionally, in each of the refractory members, a tubular insert is located within the passageway, wherein the tubular insert is comprised of a hollow tubular body with an outer diameter smaller than the diameter of the uninterrupted passageway and two tubular insert ends wherein the outer diameter of the first end is larger than the diameter of said uninterrupted passageway. The first end of the insert engages the metal structure and the second end of the insert contacts the heat-absorptive element. The first and second refractory members are then secured to the heat-absorptive element. The heat-absorptive element can optionally be a water-cooled pipe. 
         [0014]    This embodiment of the present invention may further comprise a bolt for securing the refractory members to the heat-absorptive element. Alternatively, at least one of the tubular inserts can be connected to the heat-absorptive element by way of a weld. 
         [0015]    In another variation, the inner diameter of the second end of the tubular insert is smaller than the inner diameter of the tubular body of the insert. 
     
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0016]      FIG. 1  is a longitudinal sectional view of a tubular insert. 
           [0017]      FIG. 2  is a plan view of the body of the tubular insert as it contacts an embedded metal structure. 
           [0018]      FIG. 3  is a plan view of the lip of the tubular insert as it contacts and engages the metal structure. 
           [0019]      FIG. 4  is a sectional view of a complete refractory system which illustrates the manner in which the tubular insert secures refractory members to a pair of heat-absorptive pipes by bolting the tubular insert directly to the heat-absorptive element. 
           [0020]      FIG. 5  is a schematic view of the tubular insert as it engages the metal structure and contacts the heat-absorptive element which is protected by the refractory member. 
           [0021]      FIG. 6  is a sectional view of a complete refractory system which illustrates the manner in which the tubular insert secures refractory members to a pair of heat-absorptive pipes by welding the tubular insert directly to the heat-absorptive element. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0022]    A tubular insert is shown in  FIG. 1 . The tubular insert  1  is a tubular member with an outer diameter that is consistent throughout its body  2  and includes two ends. At one end of the tubular insert, hereinafter known as the distal end, the outer diameter increases so as to form a lip, or rib,  3  around the outer circumference of the tubular insert  1 . The inner diameter of the tubular insert remains constant from the distal end until the opposite end, hereinafter known as the basal end. At the basal end, the inner diameter narrows, creating a shelf, or inverted lip  4 , around the inner circumference of the tubular insert  1 . The radial extent of this shelf  4  is such that a flat washer can rest on the area between the inner diameter of the tubular insert body  2  and the inner diameter of the shelf  4 . Optionally, this washer is a locking washer. Preferably, the difference between the inner diameter of the tubular insert body  2  and the inner diameter of the shelf  4  is between ¼″ and ½″, and ideally the difference in diameter is 11/32″. However, there remains an opening  5  in the basal end of the tubular insert  1  sufficiently large to allow the necessary angle for a weld rod so that a good structural weld can be obtained between the basal end of the tubular insert  1  and the surface of a heat-absorptive element to be protected. The opening  5  in the basal end of the tubular insert  1  is preferably between ½″ and 1″ in diameter and ideally is 25/32″ in diameter. The tubular insert  1  can be made out of any weldable metal, such as carbon steel, and is preferably constructed of stainless steel pipe, such as 304 stainless. The length of the tubular insert  1  varies depending on the density of the refractory member, with a longer tubular insert being feasible in a less dense, better insulated member. Generally, the tubular insert will be on the order of ½ the thickness of the refractory member, but ¾″ tubular inserts can also be used with 2″ thick refractory shapes. 
         [0023]    The tubular insert of the instant invention is to be used with a refractory member similar to that described in U.S. Pat. No. 4,528,672, which is expressly incorporated herein by reference. Specifically, the tubular insert of the current invention is to be used with a refractory member having a reticulated metal structure, optionally defined by a plurality of spirals, embedded within. The metal structure may, for example, be in the form of a chain mesh, similar to a link fence, or in the form of a plurality of chains. 
         [0024]    When using the tubular insert  1  to secure the refractory member to the heat-absorption element, the tubular insert  1  is positioned within a passageway  6  through the metal structure  8 . The outer diameter of the tubular insert body  2  is specially sized so that it fits securely in this passageway  6  and remains in contact with the metal structure  8  at a plurality of locations  7 , as seen in  FIG. 2 . The lip  3  located at the distal end of the tubular insert  1  has an outer diameter that is larger than the passageway  6  so that the lip  3  engages the metal structure  8 , thus preventing the tubular insert from passing completely through the passageway  6 , as seen in  FIG. 3 . As illustrated in  FIG. 5 , when the tubular insert  1  is forced into contact with the heat-absorptive element  9 , the lip  3  may collect and gather the metal structure  8 , thus increasing the contacts between the tubular insert  1  and the metal structure  8 . This connection between the tubular insert  1  and the metal structure  8  serves both to ensure that the tubular insert  1  remains securely embedded within the refractory member and to dissipate heat from the tubular insert  1  into the refractory member, preventing the rapid deterioration of the tubular insert  1 . 
         [0025]    A typical application of a bolt to connect the tubular insert to the heat-absorptive element is shown in  FIG. 4 . Two parallel water cooled metal pipes  10  are connected with a metal web  11 . The metal web  11  has a hole in it sufficient in size to allow, for example, a bolt, screw, nail or other connection device to pass through. A refractory member  12   a  and  12   b  is positioned on either side of the tandem pipes  10 . A tubular insert  1   a  and  1   b  is inserted into each of the refractory members  12   a  and  12   b  until the basal end comes into contact with the metal web  11 . Alternatively, the tubular insert  1   a  and  1   b  can be integrated into the refractory member  12   a  and  12   b , such as by a weld, adhesive, or snap-fit arrangement, for example, before the refractory member  12   a  and  12   b  is positioned adjacent the heat-absorptive element. The tubular inserts  1   a  and  1   b  are positioned so that they are in line with the hole in the web  11  allowing an open channel to exist. In one embodiment, a ⅜″ by 1″ (outer diameter) flat washer  13   a  and  13   b  is positioned on the internal washer ledge  4  of each of the tubular inserts  1   a  and  1   b . On the flat washer  13   a  is placed a ⅜″ locking washer  14  and a ⅜ screw  15  or bolt is inserted through the tubular insert  1   a  containing the lock washer  14 , through the hole in the web  11 , and eventually through the other flat washer  13   b . A ⅜″ hex nut  16  is tightened onto the screw  15  so that the two tubular inserts  1   a  and  1   b  are each secured against the web  11  of the metal pipes  10 . Because the tubular insert  1   a  and  1   b  is also securely retained within the metal structure  8  of the refractory members  12   a  and  12   b , the refractory members  12   a  and  12   b  are securely connected to the metal pipes  10 , protecting them from the surrounding environment. Other securing arrangements using the tubular inserts  1   a  and  1   b , in addition to the bolt and nut arrangement, will be appreciated to those skilled in the art. For example, a wing nut or expansion nut could be used in securing the tubular inserts  1   a  and  1   b  to the heat-absorptive element. 
         [0026]    A typical application of the use of a weld to connect the tubular insert to the heat-absorptive element is shown in  FIG. 6 . Two parallel water cooled metal pipes  10  are connected with a metal web  11 . A refractory member  12   a  and  12   b  is positioned on either side of the metal pipes  10  and a tubular insert  1   a  and  1   b  is inserted into each of the refractory members  12   a  and  12   b  until the tubular insert  1   a  and  1   b  comes into contact with the metal web  11 . A weld rod is inserted into the opening in the tubular insert  5   a  and  5   b , as will be apparent to those skilled in the art. The basal edge of the tubular insert, which is in contact with the metal web  11 , is welded to the surface of the web  11 . This weld  17  may go around the inside perimeter of the tubular insert  1   a  and  1   b  or it may be a fillet weld or a pair of such welds. Because the tubular insert  1   a  and  1   b  is also securely retained within the metal structure  8  of the refractory members  12   a  and  12   b , the refractory members  12   a  and  12   b  are securely connected to the metal pipes  10 , protecting them from the surrounding environment. 
         [0027]    The tubular insert provides many advantages over the prior art. For one, the tubular insert reduces labor and associated costs required to manufacture the refractory member. Additionally, the tubular insert reduces inventory since a single refractory shape can be attached to a heat-absorptive element in several different ways, such as through a bolting or welding process. Other advantages of the invention over the prior art will be apparent to those skilled in the art. 
         [0028]    While specific embodiments of the invention have been described in detail, it will be appreciated by those skilled in the art that various modifications and alternatives to those details could be developed in light of the overall teachings of the disclosure. The presently preferred embodiments described herein are meant to be illustrative only and not limiting as to the scope of the invention which is to be given the full breadth of the appended claims and any and all equivalents thereof.

Technology Classification (CPC): 5