Abstract:
An improved ceiling beam construction for a heating furnace in which ceiling beams having closed cross sections are adopted for utilizing the interior of the beams as ducts for passing gases through them so as to reduce spaces required for installing separate gas ducts, with a consequent decrease in the number of duct supporting fittings or fixtures.

Description:
BACKGROUND OF THE INVENTION 
     The present invention generally relates to a heating furnace for heat treating workpieces such as steel slabs, etc., and more particularly, to a ceiling beam construction for a heating furnace. 
     Conventionally, in the heating furnace of the above described type, refractory materials for a ceiling of the furnace are generally suspended from ceiling beams constituted by H-shaped steal beams, and provided above the furnace through suspension pipes, hanger tiles, etc. so as to support the weight of such ceiling refractory materials, while combustion air ducts, gas and fuel supply ducts, and exhaust ducts, etc. are normally piped or laid through reinforcing fittings and support fittings fixed to the ceiling beams. 
     Therefore, in the known ceiling beam constructions, not only is considerable space necessary for the piping of the combustion air ducts, gas and fuel supply ducts and exhaust ducts, but various kinds of fittings and fixtures are required therefor, thus resulting in an increase of the furnace size, with a consequent high cost. 
     SUMMARY OF THE INVENTION 
     Accordingly, an essential object of the present invention is to provide an improved ceiling beam construction for a heating furnace in which, by directing particular attention to ceiling beams inevitably employed in the heating furnace, ceiling beams having closed cross sections are adopted for utilizing the interior thereof simultaneously as ducts for passing gases therethrough so as to reduce the space required for installation of separate gas ducts as compared with conventional arrangements, with a consequent decrease in the number of duct supporting fittings or fixtures. 
     Another important object of the present invention is to provide an improved ceiling beam construction of the above described type which is simple in structure and highly reliable in performance, and can be readily incorporated into heating furnaces of various types at low cost. 
     In accomplishing these and other objects, according to one preferred embodiment of the present invention, there is provided a ceiling beam construction for a heating furnace which includes a ceiling portion of the heating furnace, and a ceiling beam means for supporting the load of the ceiling portion. The beam means is formed into a closed cross section so as to simultaneously utilize its interior as a gas duct so as to reduce the spaces required for installation of a separate gas duct. 
     By the arrangement according to the present invention as described above, an improved ceiling beam construction has been advantageously presented, with substantial elimination of disadvantages inherent in the conventional ceiling beam constructions of this kind. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     These and other objects and features of the present invention will become apparent from the following description taken in conjunction with the preferred embodiment thereof with reference to the accompanying drawings, in which: 
     FIG. 1 is a fragmentary side sectional view of a heating furnace in which an improved ceiling beam construction according to the present invention is employed, 
     FIG. 2 is a schematic top plan view, partly in section and illustrating only one half side, of a heating furnace to which the ceiling beam construction of FIG. 1 may be applied, 
     FIG. 3 is a side sectional view of the heating furnace of FIG. 2, and 
     FIG. 4 is a sectional view of the heating furnace taken along lines IV--IV in FIG. 3. 
     Before the description of the present invention proceeds, it is to be noted that like parts are designated by like reference numerals throughout the several views of the accompanying drawings. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring now to the drawings, there is shown, in FIGS. 1 through 3, a ceiling beam construction for a heating furnace 1 according to one preferred embodiment of the present invention. The ceiling beam construction generally includes a plurality of pairs of ceiling beam support posts S (FIG. 2) which are provided adjacent to respective outer faces of opposite side walls W of the heating furnace 1 fixed to studs R at predetermined intervals in the longitudinal direction of side walls W, ceiling beams 6 connected between each pair of said ceiling beam support posts S, a number of auxiliary ceiling beams B provided between said ceiling beams 6 so as to extend in the longitudinal direction of said heating furnace 1, a plurality of ceiling suspension members 4 such as suspension pipes or the like suitably fixed to the auxiliary ceiling beams B so as to extend in the widthwise direction of the heating furnace 1, and hanger tiles 3 (FIG. 1) integrally provided with a ceiling refractory material 2 of the heating furnace 1 and suspended from said suspension members 4, for example, by hanger metals 5. 
     It should be noted here that the ceiling beam construction described in the foregoing is not particularly essential to the present invention, but may be replaced by any other known constructions of similar type except for the construction of the ceiling beam 6 as described in detail hereinbelow. 
     Referring particularly to FIG. 1 showing the construction of the ceiling beam directly related to the present invention, the ceiling beams 6 at least in the vicinity of burners 10 arranged in the widthwise direction of the furnace 1 are each formed into a closed cross section of approximately a square configuration for simultaneously utilizing the interior of the ceiling beams 6 as combustion air supply ducts 7. 
     The combustion air supply duct 7 thus provided in the ceiling beam 6 is connected, at a suitable position, for example, at one side of the beam 6, with a combustion air supply main duct 8 which is further coupled to an air supply unit A, while the ceiling beam 6 is further formed with a plurality of through-holes 0 in position, for example, at its other side, to which a branched pipe 9 having a plurality of air supply ducts 9a each connected to the burners 10 is coupled for communication with the air supply duct 7 formed in the ceiling beam 6. For supplying fuel to a nozzle 10a of the burner 10, each burner 10 is connected to a fuel supply unit F as shown. Of course depending on the kinds of combustion air to be employed, a suitable heat insulation material 11 may be provided to line the tuner walls of the combustion air supply duct 7, and the closed cross sectional shape of the ceiling beam 6 is not limited to the square shape, but may be modified into various other configurations. 
     The ceiling beam construction of the present invention may further include an exhaust duct or flue arrangement as shown in FIGS. 2 and 3 for uniform heating of workpieces in a reduced heating time. 
     More specifically, in the conventional heating furnaces, particularly in an upper and lower combustion type walking beam furnace or the like, it is so arranged that the workpieces to be treated are heated by burners provided at upper and lower portions of the furnace, while exhaust gases produced thereby are discharged into a flue or exhaust duct through one exhaust gas discharge opening provided in the ceiling portion at the workpiece charging side of the heating furnace. Therefore, the flow of combustion exhaust gases within the heating furnace is increased in amount at the upper surface side of the workpieces to be treated, thus resulting in a temperature difference more than necessary between the upper surfaces and lower surfaces of the workpieces, with a consequent increase in the heating time as well as various inconveniences during subsequent processes such as a rolling process, etc. 
     As shown in FIGS. 2, 3 and 4, the exhaust duct arrangement may, for example, include a plurality of discharge openings DU and DL for exhaust gases respectively provided at predetermined intervals in the upper and lower portions of the workpiece charging side (i.e. left side in FIGS. 2 and 3) in the widthwise direction of the heating furnace, and connected to an upper exhaust duct or flue EU disposed between ceiling beams 6b at the left side in FIGS. 2 and 3 and also to a lower exhaust duct or flue DL provided at the lower portion of the heating furnace 1, so that the exhaust gases in the heating furnace 1 discharged from the respective discharge openings DU and DL as described above are divided to flow through the upper and lower portions of the heating furnace 1, and exhaust gas flow distribution in the widthwise direction of the upper and lower portions of the furnace 1 is made uniform, for example, by providing dampers (not shown in the Figures) in part or all of the discharge openings according to the locations or dispositions of the openings in the widthwise direction of the furnace 1, while, by providing dampers or a damper either in both or one of the upper exhaust duct EU and the lower exhaust duct EL, the flow ratio of the exhaust gases is adjusted to eliminate the temperature difference in heating in the upper and lower surfaces and longitudinal direction of the workpieces for uniform heating of the workpieces on the whole. 
     As is clear from the foregoing description, according to the present invention, since it is so arranged that the inner spaces of the ceiling beams themselves are also utilized as gas ducts to be laid at the upper portion of the heating furnace, neither particular spaces for installation of the combustion air supply ducts, exhaust ducts nor various metal fittings such as reinforcing fixtures, etc. for such ducts are required, with a consequent reduction of cost for the heating furnace. 
     Although the present invention has been fully described by way of example with reference to the accompanying drawings, it is to be noted here that various changes and modifications will be apparent to those skilled in the art. Therefore, unless such changes and modifications depart from the scope of the present invention, they should be construed as included therein.