JP4695379B2 - Elevating type firing furnace - Google Patents

Description

The present invention relates to a lifting kiln using metallic muffle for heat treating refractory or the like in a sealed state.

  For heat treatment of refractories containing carbon, such as alumina carbon refractories and magnesia carbon refractories, heat treatment of refractories impregnated with tar, pitch, etc., or when firing refractories by adjusting the firing atmosphere, etc. The refractory is heat-treated in a closed container called a muffle. A gas such as hydrogen, nitrogen, argon, or coke may be introduced into the muffle as needed. When the furnace temperature is 1100 to 1200 ° C. or higher, a refractory muffle is used, but when the furnace temperature is lower than that, a metal muffle may be used.

  Since this metal muffle can be attached and detached together with the muffle, there are advantages such as excellent handling and high work efficiency, and further, since the metal thickness is as thin as 3 to 5 mm, the loading efficiency of the refractory is increased. As a metal material, stainless steel having excellent oxidation resistance is generally used. However, in the heat treatment of a refractory containing carbon or the heat treatment of a refractory impregnated with tar, pitch or the like, the temperature inside the furnace outside the muffle reaches 500 to 1000 ° C., and even a stainless muffle is significantly deformed. . When the deformation becomes large, for example, the lid of the muffle cannot be closed, and there is a problem that the sealing state is deteriorated. For this reason, there is a problem that must be periodically replaced.

  In order to prevent the deformation, for example, Patent Document 1 proposes to use a metal container having a double structure. However, this method has a problem that the thermal efficiency is poor, and further, since the outer metal container is deformed, the replacement frequency is hardly different from the case of the single structure.

  On the other hand, the metal muffle has a cylindrical or rectangular tube shape, and the one in Patent Document 1 has a sliding door and a lid for taking in and out the refractory. Since such doors and lids are made of metal, there is a problem that they are heavy and time-consuming to handle.

Therefore, Patent Document 2 proposes a method in which a muffle is placed in the furnace in advance in an elevating type firing furnace. However, when it is used at a temperature of 500 to 1000 ° C. and is used under the condition of using a combustion burner, there is a problem that the deformation of the muffle increases and the sealing state of the lower seal portion is deteriorated.
Japanese Examined Patent Publication No. 62-14511 JP 10-141859 A

  The problem to be solved by the present invention is to prevent deformation of a metal muffle used in heat treatment of a refractory containing carbon or heat treatment of a refractory impregnated with tar, pitch, etc. It is to provide a firing furnace.

The present invention includes three or more metal muffles each having a box-type or cylindrical-type muffle lid having a ceiling without a bottom and a bottom plate, and the muffle lids are arranged in a longitudinal direction with a predetermined interval in a furnace. The bottom plate is an elevating type firing furnace installed in an elevating hearth, and the muffle lid is entirely composed of a corrugated metal plate. A pair of opposed combustion burners facing each other, one combustion burner of the pair of opposed combustion burners being installed in the upper back and the other combustion burner installed in the lower front side, and this pair of combustion burners By installing one combustion burner of the pair of combustion burners adjacent in the longitudinal direction at the back and the other combustion burner above the front, the combustion burners are staggered vertically and horizontally Characterized in that installed in.

The metal muffle used in the elevating type firing furnace of the present invention is hardly deformed even when used in an atmosphere of 500 to 1000 ° C., and the lifetime is significantly longer than that of a conventional metal muffle, so the firing cost is low. descend. Further, since the heat radiation in the muffle becomes more uniform due to the corrugated structure, the temperature distribution in the muffle becomes uniform, and the quality variation of the object to be fired is reduced.

  Moreover, in the elevating-type firing furnace of the present invention, the metal muffle muffle lid is installed in the furnace, but by using a corrugated metal plate for the entire surface, it can be used for a long time without deformation even at 500-1000 ° C. can do.

  Furthermore, if a plurality of muffle lids are arranged in the elevating-type firing furnace and a burner port is provided between the muffle lids, the temperature distribution inside the metal muffle is uniform, and the durability of the metal muffle is improved. .

A first embodiment of a metal muffle used in the elevating firing furnace of the present invention will be described with reference to FIGS. FIG. 1 is a vertical cross-sectional view of a metal muffle used in the elevating-type firing furnace of the present invention, FIG. 2 is a plan view thereof, and FIG. 3 is a view taken along line AA in FIG.

  As shown in FIG. 1, the metal muffle 1 includes a muffle bottom plate 3 and a muffle lid 2 that has a closed structure by fitting a lower end portion into a sand seal groove 12 of the muffle bottom plate 3. The muffle lid 2 has a box shape without a bottom, the side wall is composed of four corrugated metal plates 4 for the side, and the ceiling is composed of one corrugated metal plate 5 for the ceiling. The side corrugated metal plate 4 is arranged in a direction in which the wave ridge line 6 is substantially vertical, and the four corner portions 7 with which the corrugated metal plate for side surface 4 contacts are fixed by welding. The formed side wall is formed. Further, the muffle lid 2 does not use a frame or the like, and maintains strength as a structure only with a corrugated metal plate.

  In the corrugated metal plate, elongate metal plates are welded and fixed to the upper and lower end surfaces of the ridgeline of the wave for sealing. That is, a total of four upper seal plates 8 are welded and fixed to the upper end surface of the corrugated metal plate 4 for side surfaces, and a total of four lower seal plates 9 are also welded to the lower end surface. These seal plates are about the height of the wave.

  In the corrugated metal plate 5 for the ceiling, the end face parallel to the ridge line of the wave is welded and fixed to the upper seal plate 8 on the side wall, and the end face perpendicular to the ridge line is welded to the upper seal plate 8 on the side wall via the upper side seal plate 10. It is fixed.

  The corrugated metal plate 4 for the side surface has a square cylindrical seal frame 11 at the lower part thereof. The seal frame 11 is formed of a flat rectangular flat plate having no irregularities. The seal frame 11 is provided to enter the groove 12 of the muffle bottom plate 3 and perform a sand seal.

  On the other hand, the muffle bottom plate 3 has, on its surface, a continuous groove 12 that goes around the outer periphery, and the groove 12 includes a rectangular inner frame 13 and an outer frame 14. This groove 12 contains a refractory powder and serves as a sand seal. When the seal frame 12 below the muffle cover 2 is inserted into the groove 12 of the muffle bottom plate 3, the entire metal muffle 1 is almost sealed. When this metal muffle 1 is installed in an elevating type firing furnace, a muffle bottom plate 3 is placed on the elevating type hearth, a refractory or the like is placed on the muffle bottom plate 3, and the muffle lid 2 is covered from above. The outside air can be almost blocked.

  In addition, the metal muffle of the present invention has a structure in which corrugated metal plates for side surfaces constituting the side wall thereof are integrated, whereby deformation is further reduced and durability is improved. If it is a square tube type muffle like a present Example, the whole side wall will be integrated by welding and fixing the four corner parts 7 of the corrugated metal plate 4 for four side surfaces in the perpendicular direction. For this reason, the strain generated in the side wall is absorbed by the entire deformation, the deformation is less likely to occur, and the stress absorbing ability is further increased. Further, when the ceiling is integrated in addition to the side wall, a higher effect can be obtained. In this embodiment, welding is fixed for integration, but other means such as fixing with bolts and nuts may be used.

  In the case where the corrugated metal plate is provided on the side wall, if the corrugated metal plate is disposed so that the ridge line of the wave is directed substantially in the vertical direction, the strength as the structure is increased, so that there is an effect that deformation due to thermal stress is also reduced. The shape of the metal muffle is not particularly limited, and can be designed in a free shape such as a box shape or a cylindrical shape.

  The corrugated metal plate used in the present invention has a corrugated cross section. For example, the corrugated metal plate shown in FIG. 4 has a sharp wave apex, the wave has a smooth wave apex as shown in FIG. For example, a type with a flat wave apex can be used. The wave size may be determined according to the size of the muffle and the use conditions, but the wave height H is preferably 10 to 100 mm and the wave length L is more preferably 10 to 150 mm. When the wave height H is less than 10 mm, the stress absorption effect is small and deformation is likely to occur, and when it exceeds 100 mm, the stacking efficiency of the object to be fired is poor and impractical. If the length L of the wave is less than 10 mm, it takes a lot of time to manufacture the metal plate, resulting in an increase in cost. If the wave length L exceeds 150 mm, the stress absorption effect is small and the metal plate is easily deformed. Even if the corrugated metal plate has such a corrugated structure and is relatively thin, a large deformation hardly occurs, and a range of 0.5 to 5 mm is more preferable. If it is less than 0.5 mm, there is a problem in durability, and if it exceeds 5 mm, it becomes heavy and is not practical. The corrugated metal plate is preferably made of stainless steel or the like from the viewpoint of durability.

  As previously described with reference to FIGS. 1 to 3, the lower portion of the corrugated metal plate 4 has a cylindrical sealing frame 11 with a flat surface so as to have a generally used sand seal structure. Yes. This is because in order to obtain a sand seal structure with a corrugated metal plate, the width of the groove 12 becomes wide in consideration of the deformation allowance, so that the stacking efficiency of the objects to be fired deteriorates. Further, by adopting a strong structure such as forming only the seal frame 11 with a thick metal plate, the influence on the seal frame 11 can be suppressed even if the corrugated metal plate is slightly deformed. For this reason, there is no problem as long as the seal frame 11 is thick enough not to adversely affect the stacking efficiency of the objects to be fired, and the height is the required minimum height of about the depth of the groove 12 plus α. And although the magnitude | size is decided according to the magnitude | size of a muffle, it is more preferable that height is 3 to 20% of the height of a muffle. If it is less than 3%, it is too short to obtain the effect of the sand seal, and if it exceeds 20%, it tends to be deformed, and when the muffle cover is placed, the balance is lost or the groove 12 is difficult to enter. The thickness is more preferably 2 to 20 mm. If it is less than 2 mm, it tends to be deformed.

Next it shows the lifting kiln of the present invention using a metal muffle.

  FIG. 7 is a vertical sectional view of an elevating-type firing furnace using a metal muffle, and FIG. 8 is a view taken along the line BB in FIG. The elevating firing furnace 20 includes a furnace body 21 and four elevating hearths 22. The furnace body 21 has a box shape, and the furnace wall 23 is lined with an iron skin on the outside and a refractory on the inside. The furnace body 21 is fixed to the floor by a plurality of pillars (not shown). A traveling carriage 25 that travels on a rail 24 is provided under the furnace body 21, and an elevator 26 is provided on the traveling carriage 25. As the elevator 26, a general elevator using a motor or hydraulic pressure can be used.

  Four muffle lids 2 of metal muffle 1 are suspended from the ceiling at approximately equal intervals in the furnace. Under the muffle lid 2, an elevating hearth 22 can be attached and detached by moving up and down by an elevator 26. A muffle bottom plate 3 is installed on the elevator hearth 22. The elevating hearth 22 is fixed so as not to be lowered by a stopper (not shown) when it is raised.

  Between each of the muffle lids 2 in the furnace, there are two burner ports 27, one at the upper part and one at the lower part, on the long side furnace wall. For this reason, since the flame of combustion gas does not directly hit the metal muffle 1, the deformation of the metal muffle 1 can be suppressed.

  The burner ports 27 are provided so that the top, bottom, left and right are staggered. For example, in FIGS. 7 and 8, the burner port 27a is in the upper furnace wall, the burner port 27b is in the lower furnace wall, the burner port 27c is in the lower furnace wall, and the burner port 27d is in the upper front. It is a furnace wall. Two burner ports 27 are similarly owned between the metal muffle 1 at the end and the furnace wall 28 on the short side. By disposing the burner port 27 in this way, the combustion gas between the muffle lids 2 forms a spiral, and the temperature distribution in the furnace becomes more uniform. Although the muffle lid 2 is hung by a hanging metal fitting 29, it has a structure that can be attached and detached although not shown. The metal muffle 1 is the same as that shown in FIGS.

  Next, an operation method of the elevating type firing furnace 20 will be described. First, the elevator hearth 22 is lowered by the elevator 26 on the traveling carriage 25 and moved to a loading / unloading place which is another place. In the loading / unloading place, a refractory 30 as a fired product is loaded on the muffle bottom plate 3 with the elevating hearth 22 placed on the traveling carriage 25. After loading, the traveling carriage 25 moves below the furnace main body 21, and the elevator 26 is raised by the elevator 26 and fitted into the furnace port 31 of the furnace main body 21, so that the groove 12 (see FIG. 1), the lower part of the muffle lid 2 is fitted. Then, the insertion operation of the raising / lowering hearth 22 is completed by applying a stopper to prevent the fall. The four raising and lowering hearths 22 are put in order, and when the insertion is completed, firing is started. After firing, the up-and-down hearth 22 is placed one by one on the lifting carriage 25 and moved to a loading / unloading place. After the fired product is lowered, the refractory 30 to be heat-treated next is loaded.

  In this way, in the case of an elevating type firing furnace, since the carriage does not move in the furnace, unlike the tunnel type firing furnace, the muffle can be designed so that the flame of the combustion gas does not directly touch the muffle life. Excellent in terms. Furthermore, there is a merit that the work efficiency is high because the furnace floor can be attached and detached simultaneously and the muffle can be attached and detached. Therefore, by applying the metal muffle of the present invention, it becomes a firing furnace that can bring out the merit of being difficult to deform to the maximum.

  And by setting it as the raising / lowering hearth using several metal muffles, there exists a merit which the temperature distribution in a muffle becomes uniform compared with the metal muffle furnace of the same volume. And since it is set as the structure which lets combustion gas pass between metal muffles, durability of metal muffles improves.

  The present invention can be used for heat treatment of a carbon-containing refractory, firing of the refractory in an atmosphere, etc. In particular, when heat treating a refractory impregnated with tar or pitch, the furnace temperature becomes 500 to 1000 ° C., Therefore, the burner is used and the metal muffle itself is also large. Therefore, it is preferable to use the metal muffle of the present invention because the durability is remarkably improved.

It is a vertical sectional view of a metal muffle used in the elevating firing furnace of the present invention. It is a top view of the metal muffle used for the raising / lowering baking furnace of this invention. It is an AA arrow line view of FIG. It is sectional drawing of a corrugated metal plate (type with which the peak of the wave was sharp). It is sectional drawing of a corrugated metal plate (type with the smooth top of a wave). It is sectional drawing of a corrugated metal plate (type with the flat top of a wave). It is a vertical sectional view of the elevating type firing furnace of the present invention using a metal muffle. It is a BB arrow line view of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Metal muffle 2 Muffle lid 3 Muffle bottom plate 4 Corrugated metal plate 5 Side corrugated metal plate 6 Wave ridgeline 7 Corner part 8 Upper seal plate 9 Lower seal plate 10 Upper side seal plate 11 Seal frame 12 Groove 13 Inner frame 14 Outer frame 20 Elevating type firing furnace 21 Furnace body 22 Elevating type hearth 23 Furnace wall 24 Rail 25 Traveling carriage 26 Elevator 27 Burner port 28 Furnace wall 29 on the short side 30 Refractory material 31 Furnace port

Claims (1)

There are three or more metal muffles each having a box-type or cylindrical-type muffle lid having a bottom and a ceiling, and a bottom plate, and the muffle lids are arranged in a row along a longitudinal direction at a predetermined interval in the furnace. In the elevating firing furnace installed in the elevating hearth, the bottom plate is
The entire surface of the muffle lid is made of a corrugated metal plate,
A pair of combustion burners facing the inside of the furnace and facing each other between the muffle lids,
Of the pair of opposed combustion burners, one combustion burner is installed at the upper back and the other combustion burner is installed at the lower front, and one of the pair of combustion burners adjacent to the pair of combustion burners in the longitudinal direction. the combustion burner at the back of the lower, by installing the other combustion burner in front of the upper, lifting kiln you characterized in that installed combustion burner as vertically and horizontally is staggered.

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