Patent Publication Number: US-6221313-B1

Title: Taphole knockout device

Description:
FIELD OF THE INVENTION 
     The present invention relates to an apparatus for removing a taphole sleeve from a furnace wall, and more particularly to a pneumatic operated device that imparts a percussive action on the taphole sleeve. 
     BACKGROUND OF THE INVENTION 
     A taphole is an opening through a wall of a furnace for allowing molten metal within the furnace to exit therefrom. A taphole is defined by a taphole sleeve, which is basically a nozzle formed of special refractory material. The furnace wall is typically comprised of an outer metal shell, the interior of which is lined with a refractory material. The taphole opening is defined by either a single elongated taphole sleeve, or by a plurality of axially aligned, shorter sleeves. A concentric wall of refractory bricks or blocks typically surrounds the taphole sleeve(s), and a refractory material, i.e., a filler material, such as mortar, a castable or a dry sintered material fill the void or space between the concentric wall and the taphole sleeve(s). 
     Molten metal, slag and other impurities that flow through the taphole sleeve(s) have abrasive properties and eventually wear away the bore of the taphole sleeve(s) until there is insufficient wall thickness to sustain the flow of metal without the metal burning through the sleeve(s) into the filler material. At this point, removal and replacement of the taphole sleeve(s) is required. At the present time, taphole sleeves are generally removed by a worker using a jackhammer to chisel away the filler material and sleeve. Because of energy costs, the furnace is normally not allowed to cool and removal of the taphole sleeve generally occurs while the furnace is still hot. In this respect, the inner portion of the furnace may still be at temperatures in excess of 2,000° F., presenting a dangerous situation for a worker removing the taphole sleeve(s). 
     The present invention relates to a device for removing a taphole sleeve from within the furnace, which device does not require an individual in the vicinity of the taphole sleeve. 
     SUMMARY OF THE INVENTION 
     In accordance with the present invention there is provided a knockout device for removing a taphole sleeve from the furnace wall. The device is comprised of a pneumatic hammer having an elongated body and a weight that is reciprocally movable by air pressure along the body. The body has a first end with an inlet for receiving air under pressure from an external source and a second end. A metal block is attached to said second end of the body. The block has a planar surface dimensioned to rest upon an upper end of the taphole sleeve. A locating pin extends from the block and is dimensioned to be received within an axial bore defined by the taphole sleeve. A protective housing surrounds the pneumatic hammer and defines a cavity thereabout. The protective housing has openings therethrough to allow air from the pneumatic hammer to vent from the cavity. 
     It is an object of the present invention to provide a device for removing a taphole sleeve from a furnace wall. 
     It is another object of the present invention to provide a device as described above that is operable within a furnace maintained at an elevated temperature. 
     It is another object of the present invention to provide a device as described above that does not require manual manipulation or the presence of a worker near the taphole sleeve. 
     It is another object of the present invention to provide a device as described above that utilizes a reciprocal hammer to impart a percussive action to the taphole sleeve. 
     A still further object of the present invention is to provide a device as described above that includes a protective housing wherein the pneumatic hammer is shielded from the elevated furnace temperature. 
     A still further object of the present invention is to provide a device as described above that is designed to utilize airflow from the pneumatic hammer to maintain a cooling effect thereon. 
    
    
     These and other objects will become apparent from the following description of a preferred embodiment of the invention taken together with the accompanying drawings. 
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention may take physical form in certain parts and arrangement of parts, a preferred embodiment of which will be described in detail in the specification and illustrated in the accompanying drawings which form a part hereof, and wherein: 
     FIG. 1 is a partially sectioned, elevational view of a taphole knockout device illustrating a preferred embodiment of the present invention; 
     FIG. 2 is an enlarged view of the taphole knockout device shown in FIG. 1; and 
     FIG. 3 is a sectional view taken along lines  3 — 3  of FIG.  1 . 
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENT 
     Referring now to the drawings wherein the showings are for the purpose of illustrating a preferred embodiment of the invention only, and not for the purpose of limiting same, FIG. 1 shows a taphole knockout device  10  in accordance with the present invention. Taphole knockout device  10  is shown in position relative to a taphole sleeve  22 . Taphole sleeve  22  is part of a furnace wall, designated  24  in the drawings. Furnace wall  24  is generally comprised of a metal shell  26  that is lined with a refractory material  28 . A plurality of refractory bricks  32  define a cylindrical opening through metal shell  26  and refractory material  28 . Taphole sleeve  22  is held in place in the opening defined by refractory bricks  32  by a refractory mortar, castable or dry sintered material  34 . Taphole sleeve  22  includes a lower end block  36  that is held in place by a flange ring (not shown) that is mounted to the outer shell of the furnace in a conventionally known manner. An axial bore  38  having a flared upper end is defined through taphole  22  and end block  36 . Taphole sleeve  22 , furnace wall  24  and end block  36  have been described for the purpose of illustration, and in and of themselves, form no part of the present invention. 
     Taphole knockout device  10  includes a pneumatic hammer designated  50  in the drawings. Pneumatic hammer  50  is generally comprised of an elongated body  52  having a weight  54  that is reciprocally movable along body  52  by means of pneumatic pressure. Pneumatic hammer  50  is preferably an extractor type hammer conventionally used in driving or removing drill rod or casing used in oil drilling. An extractor hammer of the type manufactured by Holt Manufacturing Company finds advantageous application in the present invention. Weight  54  is a cylindrical sleeve that is reciprocally movable under pneumatic pressure along body  52 . Body  52  includes a first end  52   a  that is threaded and a second end  52   b  having an adapter  56  thereon for connection to a hose  58  that is connectable to an external source of pressurized air. 
     An adapter/anvil  62  is attached to the threaded end  52   a  of body  52 . Adapter/anvil  62  is generally cylindrical in shape and has an upper portion designated  62   a  of reduced diameter defining a shoulder  64 . Adapter/anvil  62  includes an axially lined bore at one end dimensioned to receive an elongated pin  68 . Pin  68  is dimensioned to snuggly fit within axial bore  38  defined by taphole sleeve  22 . In this respect, it will be appreciated by those skilled in the art that the bore size (diameter) of different tapholes used in different furnaces may vary and that pin  68  is adapted to be used in a taphole that has “opened up” (i.e., the diameter of the bore has increased) due to erosion and wear. Thus, pin  68  is dimensioned to snuggly fit into a worn taphole. Locating pin  68  is fastened to adapter/anvil  62  by a fastening element  72  extending transversely through adapter/anvil  62  and locating bar  68 . In the embodiment shown, counterbores  74  are formed in adapter/anvil  62  such that fastener  72  does not extend beyond the outer periphery of adapter/anvil  62 . As shown in FIG. 1, anvil/adapter  62  includes a lower planar, surface dimensioned to rest upon the upper edge of taphole sleeve  22 . 
     A protective housing  80  is dimensioned to surround pneumatic hammer  50  and capture upper portion  62   a  of adapter/anvil  62 . In the embodiment shown, housing  80  is a cylindrical pipe having an inner diameter closely matching the outer diameter of upper portion  62   a  of adapter/anvil  62 . As best seen in FIG. 2, housing  80  defines an annular cavity  82  that surrounds pneumatic hammer  50  and allows for free movement of weight  54 . Openings  84  through housing  80  allow cavity or chamber  82  to communicate outside housing  80 . An insulating jacket  86  surrounds housing  80  to thermally insulate cavity  82  from the surrounding environment. Jacket  86  may be formed from a variety of different types of insulating blanket-like material. In the embodiment shown, jacket  86  is preferably formed of a high temperature blanket material such as KAOWOOL. Jacket  86  is preferably at least two inches thick. The refractory blanket may be secured to housing  80  by wire or other conventional fastening means capable of withstanding the elevated temperatures within a furnace, such as metal straps or bands. 
     Pneumatic hammer  50  is attached to the upper end of housing  80 . In the embodiment shown, a hammer bracket  92 , best seen in FIG. 2, is fixedly attached to adapter  56  on pneumatic hammer  50 . Bracket  92  has a cross-shaped configuration as best seen in FIG.  3 . Bracket  92  is welded to a cylindrical collar  94  that in turn is welded to the adapter  56  portion of pneumatic hammer  50 . As best seen in FIG. 3, reinforcing pins are added through collar  94  to reinforce same. Bracket  92  is dimensioned to be fastened to housing bracket  102 . Housing bracket  102  is basically a cylindrical plate having a rectangular opening formed therein, best seen in FIG.  3 . Bracket  102  is welded to the inner surface of housing  80  and includes reinforcing pins  106  inserted through housing  80  into bracket  102 . Hammer bracket  92  is attached to housing bracket  102  by conventional fasteners  108 . Lift bars  112  are attached to housing  80  by conventional fasteners  114 . The upper ends of lift bar  112  are attached to a handle  116  having an opening  118  dimensioned to receive a hook chain or the like from an overhead conveyer. In the embodiment shown, an air hose  58  is shown attached to the upper end of a pneumatic hammer  50  to actuate the same. 
     Referring now to the operation of taphole knockout device  10 , device  10  is adapted to be suspended by an overhead crane or conveyor (not shown) by means of a hook or chain extending through opening  118  in handle  116 . Hose  58  is connected to an external source of pressurized air, conventionally found in an industrial plant to operate pneumatic hammer  50 . With taphole knockout device  10  suspended by an overhead crane, taphole knockout device  10  assumes a vertical orientation as shown in FIG.  1 . By means of an overhead crane, locating bar  68  is aligned with bore  38  of taphole sleeve  22 . Taphole knockout device  10  is then lowered until lower surface of adapter/anvil  62  comes to rest upon the upper edge of sleeve  22 . Pressured air is then directed through hose  58  to cause weight  54  on pneumatic hammer  50  to reciprocate along body  52 , thereby imparting percussive movement and vibration to taphole sleeve  22 . The weight of taphole device  10  together with the percussive movement of pneumatic hammer  50 , vibrates and loosens taphole sleeve  22  and mortar  34 , thus releasing taphole sleeve  22  from furnace wall  24 . As shown in the drawings, the dimensions of adapter/anvil  62  allows taphole knockout device  10  to descend partially into the bore defined by refractory bricks  22  without contacting same. 
     Still further, in accordance with the present invention, air exhausted from pneumatic hammer  50  is forced through cavity  82  in housing  80  and is exhausted through opening  84 . In this respect, the escaping air from pneumatic hammer  50  produces an air flow around pneumatic hammer  50  within housing  80  that maintains the temperature within cavity  82  at a temperature much less than the surrounding interior of the furnace. In this respect, the same air that actuates and operates pneumatic hammer  50  also provides a cooling jacket around pneumatic hammer  50  to prevent the elevated internal furnace temperature from adversely affecting the operation of hammer  50 . 
     The foregoing description is a specific embodiment of the present invention. It should be appreciated that this embodiment is described for purposes of illustration only, and that numerous alterations and modifications may be practiced by those skilled in the art without departing from the spirit and scope of the invention. For example, although knockout device  10  is depicted and described as suspended vertically from an overhead crane for removing a taphole from inside a furnace, device  10  may be mounted or supported by other mechanical devices, such as a forklift or the like in different orientations and used from outside a furnace. It is intended that all such modifications and alterations be included insofar as they come within the scope of the invention as claimed or the equivalents thereof.