JP2007240053A - Suspended ceiling structure of atmosphere furnace - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a suspended ceiling structure of an atmosphere furnace capable of decreasing probability of troubles caused by thermal expansion/thermal contraction of a ceiling refractory by eliminating factors preventing smooth movement at a contact portion, of ceiling metal hangers. <P>SOLUTION: Pipe materials 6, 12 of upper and lower two stages, as the ceiling metal hangers are disposed at a lower part of a supporting beam 2 and at an upper part of the ceiling refractory 4 in a state of intersecting with each other, and an anchor brick metal hanger 6 suspending the ceiling refractor 4 is hooked at a side of the upper pipe material 6 through a plurality of anchor bricks 5. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a ceiling suspending structure of an atmosphere furnace in which a ceiling refractory constructed by an irregular refractory in a rectangular or ring shape is supported by a plurality of support beams, and the thermal expansion / contraction of the ceiling refractory. The present invention relates to a ceiling-suspended structure that can reduce the risk of trouble caused by.

Atmosphere furnaces with ceiling refractories built in a rectangular or ring shape with irregular refractories are heated furnaces that heat steel materials under specified non-oxidizing atmosphere conditions, and iron oxide ingots that contain a reducing agent. It is generally used as a reduction furnace for heating an object or the like under a predetermined atmospheric condition.
Here, FIG. 3 shows a cross-sectional view of the upper part of a general atmospheric furnace constructed with an irregular refractory. FIG. 4 shows a cross section taken along the line AA of FIG. In this atmosphere furnace, the refractory in the upper part of the furnace body is the side wall refractory 3, the ceiling refractory 4, and the anchor brick 5, and the ceiling hanging hardware is the pipe 6 fixed to the support beam 2 and the anchor brick 5. This is an anchor brick hanging hardware 7 made of round steel wound around the neck portion of the steel plate.

The suspended ceiling structure as shown in FIGS. 3 and 4 has the anchor refractory 4 placed below the support beam 2 via the plurality of anchor bricks 5 embedded in the ceiling refractory 4, This is a structure that is hung with a pipe 6 that is a ceiling hanging hardware (Patent Document 1).
The plurality of anchor bricks 5 are embedded in an irregular refractory when the furnace ceiling is constructed with an irregular refractory, and the bellows-like ribs and the irregular refractory are brought into close contact with each other. Then, in a state where the anchor brick hanging hardware 7 is wound around the neck of the anchor brick 5, the ceiling refractory 4 is lifted to the position of the support beam 2 which is a structural member, and then the pipe material 6 fixed to the support beam 2 is attached to the anchor 6 By hooking the upper part of the brick hanger 7, it is hung horizontally on the support beam 2 made of H-shaped steel as a structure. In this example, the pipe material 6 which is a ceiling hanging hardware is fixed to the supporting beam 2 of the H-shaped steel which is a structure.

FIG. 5 shows the thermal expansion occurring in the refractory of this atmospheric furnace, and FIG. 6 schematically shows a trouble example caused by the thermal expansion / shrinkage occurring in such a refractory. is there.
The arrow α indicates the thermal expansion of the side wall refractory 3 in the height direction, and β indicates the thermal expansion of the ceiling refractory 4 in the furnace width direction. Furthermore, the ceiling refractory 4 undergoes thermal expansion in a direction perpendicular to the furnace width direction. In FIG. 5, W indicates the direction of the dead weight acting on the ceiling refractory 4.

  The refractory used in the atmosphere furnace is thermally expanded as the furnace temperature rises. For example, in the case of an alumina-based refractory furnace material, the expansion coefficient is 0.5 to 0.8% at 1000 ° C. and 0.9 to 1.2% at 1400 ° C. Further, in the case of a refractory furnace material in which magnesia is added to an alumina system, an alumina-magnesia chemical reaction (spinel reaction) occurs at a high temperature, so that the thermal expansion coefficient is further increased.

  The refractory starts to shrink as the furnace temperature decreases, but it does not always return to the dimensions before the temperature rise. Also, since there is a temperature difference between the inside and outside of the furnace in an actual atmospheric furnace, there is a difference in the amount of thermal expansion and shrinkage, and the amount of the change due to the change of structure due to slag and gas component infiltration into the refractory Will also change over time. For this reason, it is extremely difficult to accurately estimate the amount of thermal expansion and contraction generated in the refractory in the atmosphere furnace and the various stresses generated inside the refractory because the various events described above are complicated. It is.

  At the time of designing the furnace body, it is common to provide the gap 8 in consideration of thermal expansion / contraction generated in the refractory of the atmospheric furnace. However, when the amount of thermal expansion is unexpected, as shown in FIG. 6, the ceiling refractory 4 is pushed up by the side wall refractories 3 at both ends in the furnace width direction, so that the furnace width of the ceiling refractory 4 is increased. There is a case where a large crack 9 enters the central portion in the direction, the neck portion 10 of the anchor brick 5 is cut, and finally the ceiling refractory 4 falls off, resulting in a major trouble.

To solve such a problem, as shown in FIG. 7, a suspended ceiling structure of an atmosphere furnace is disclosed (Patent Document 2) in which a shaped steel ceiling hanging hardware 11 can escape upward.
In the suspended ceiling structure of the atmosphere furnace described in Patent Document 2, since a ceiling steel fixture 11 made of steel is placed on the support beam 2 as a structural member, a large crack is formed in the center of the ceiling refractory 4 in the furnace width direction. 9 is superior to the suspended ceiling structure described in Patent Document 1 in that the risk of a major trouble of entering 9 can be extremely reduced.
JP-A-62-245082 JP 2004-3729 A

By the way, the suspended ceiling structure of the atmosphere furnace described in Patent Document 2 is configured such that the ceiling hanging hardware 11 made of shape steel is placed on the support beam 2 to prevent the hardware from restraining the ceiling refractory. The structure can be stabilized.
Further, the ceiling structure of the atmosphere furnace described in Patent Document 2 is such that the upper part of the anchor brick hanging hardware 7 wound around the neck portion of the anchor brick 5 is hooked on the shape steel ceiling hanging hardware 11 and the ceiling refractory 4 is supported by the support beam 2. It is structured to hang below. For this reason, as shown by the arrows in FIG. 7, “the anchor brick 5 can be prevented from being deformed / dropped off from the hanging hardware and the anchor brick due to movement in the furnace radial direction”.

However, the suspended ceiling structure of the atmosphere furnace described in Patent Document 2 has the following technical problems.
(A) Using the shape steel as the ceiling hanger 11, the anchor brick hanger 7 made of round steel is received at the flange portion. Therefore, when the anchor brick 5 moves due to thermal expansion / shrinkage of the ceiling refractory, the resistance at the contact portion between the ceiling hanging metal and the round steel hinders smooth movement, and the anchor brick hanging hardware 7 and the anchor brick 5 are prevented. There is a problem that there is a great risk of deformation and dropout.

  (B) The L-shaped hooking portion of the ceiling steel fitting 11 made of shape steel is put on the flange portion of the supporting beam 2 made of shape steel. Therefore, since the L-shaped hook portion and the flange portion of the support beam 2 are in contact with each other, the resistance at the contact portion between the ceiling hanging hardware when the anchor brick 5 moves due to the thermal expansion / contraction of the ceiling refractory. This hinders smooth movement, and there is a problem that the anchor brick hanging hardware 7 and the anchor brick 5 are likely to be deformed and dropped.

That is, since the suspended ceiling structure of the atmosphere furnace described in Patent Document 2 is a structure in which the resistance at the contact portion between the ceiling hanging hardwares is large, when the anchor brick 5 moves due to thermal expansion / contraction of the ceiling refractory, Smooth movement of the brick 5 cannot be guaranteed.
The present invention eliminates the above-mentioned problems of the prior art and eliminates as much as possible the factors that hinder smooth movement at the contact part between the ceiling hanging hardware, thereby causing trouble caused by thermal expansion / shrinkage of the ceiling refractory. An object of the present invention is to provide a suspended ceiling structure for an atmospheric furnace capable of reducing the risk of the above.

This inventor solved the said subject by setting it as the following suspended ceiling structures.
The present invention is as follows.
1. In a suspended ceiling structure of an atmospheric furnace in which a ceiling refractory is supported by a plurality of support beams, a pipe suspended in two stages above and below the support beams and above the ceiling refractory is connected to a ceiling. A suspended ceiling structure for an atmospheric furnace, wherein the ceiling brick is suspended by a plurality of anchor bricks, and the anchor brick hanging hardware is hooked to the upper pipe member. .

2. Both the upper and lower two-stage pipe materials are steel pipes having a circular outer shape. The suspended ceiling structure of the atmosphere furnace described in 1.
3. The lower tube is inserted into the frame space of the rectangular frame support metal provided on the support beam, and is held in the frame of the rectangular frame support metal by contacting the lower part of the frame. The above-mentioned 1. characterized by being made. Or 2. The suspended ceiling structure of the atmosphere furnace described in 1.

  ADVANTAGE OF THE INVENTION According to this invention, the resistance in the contact part of ceiling hanging hardware can be made small. Therefore, the movement of the anchor brick caused by the change in the furnace temperature can be made smooth, and the risk of trouble caused by the thermal expansion / contraction of the ceiling refractory can be reduced.

A specific configuration example of the present invention will be described below with reference to FIGS.
FIG. 1A is an upper cross-sectional view showing a ceiling hanging structure of an atmospheric furnace according to an embodiment of the present invention, and FIG. 1B is a partial cross-sectional view showing the main part thereof. 2 is a cross-sectional view taken along the line BB in FIG.
A plurality of anchor bricks 5 are embedded in the ceiling refractory 4 as shown in FIGS. In the atmosphere furnace according to the embodiment of the present invention, a ceiling refractory 4 is provided below a support beam 2 via a plurality of anchor bricks 5 and an anchor brick hanging hardware 7 wound around the neck portion of the ceiling refractory 4 by a plurality of support beams 2. It has a support structure that is suspended horizontally. This support structure is the same as the conventional one.

The ceiling suspension structure of the atmospheric furnace according to the embodiment of the present invention employs the above-described support structure, and as shown in FIGS. 1 and 2, below the support beam 2 and above the ceiling refractory 4; The upper and lower pipe members 6 and 12 are arranged so as to cross each other.
Here, as shown in the drawing, the contact portions of the upper two pipe members 6 and 12 that are the ceiling hanging hardware are orthogonal to each other in a state in which the upper pipe member 6 is on the lower pipe member 12. Therefore, since the contact portion is in a contact state where the pipe members intersect with each other, the resistance at the contact portion between the ceiling hanging hardware can be reduced. Therefore, when the anchor brick 5 moves due to the thermal expansion and contraction of the ceiling refractory, the smooth movement of the anchor brick 5 can be ensured. Therefore, the upper pipe 6 that suspends the ceiling refractory 4 is the lower pipe 12. It is possible to move smoothly upward in the tube axis direction of the lower tube material 12.

Moreover, as shown in FIGS. 1A and 1B, the ceiling refractory 4 is hung on the upper pipe member 6 via a plurality of anchor bricks 5 embedded in the ceiling refractory 4. Anchor brick hanging hardware 7 is hooked.
8A to 8C show a support structure for the anchor brick 5 employed in the atmospheric furnace according to the embodiment of the present invention. The hook shape with the upper pipe member 6 of the anchor brick hanger 7 is not limited to the shape generally implemented as shown in FIGS.

However, it is preferable that the contact resistance between the ceiling hanging hardware at the hooking portion between the anchor brick hanging hardware 7 obtained by processing the round bar into a dedicated shape and the upper pipe 6 is minimized.
According to the ceiling hanging structure of the atmosphere furnace according to the embodiment of the present invention described above, the resistance at the contact portion between the ceiling hanging hardware can be reduced, and the anchor brick 5 moves due to the thermal expansion / contraction of the ceiling refractory. At this time, the smooth movement of the anchor brick 5 can be guaranteed. Therefore, the smooth movement at the contact portion between the ceiling hanging hardwares is hindered, and the risk of deformation / dropping of the ceiling refractory 4, the anchor brick 5 and the anchor brick hanging hardware 7 can be reduced.

In addition, it is necessary to secure the strength and dimensions necessary to support the ceiling refractory 4 by using a steel pipe having a circular outer shape for both the lower two-tier pipe materials (6) and (12), in addition to being used for the ceiling hanging structure. This is preferable because the degree of freedom of selection is high.
Moreover, the arrangement | positioning space | interval of the upper pipe material 6 can be determined according to the weight of the ceiling refractory 4 per 1 span (a span means the division into which an amorphous refractory is poured in constructing a furnace ceiling). . Further, the number of anchor bricks 5 embedded per span can be stably suspended via anchor brick hanging hardware 7 in which the ceiling refractory 4 per span is attached to the neck of the anchor brick 5. Design optimally. At that time, the weight of the ceiling refractory 4 per span, the refractory characteristics such as the expansion rate of the refractory used, the operation temperature and the like are taken into consideration.

The weight of the ceiling refractory 4 per span is determined according to the value obtained by dividing the total weight of the amorphous refractory to be used by the number of spans, and can therefore be obtained at the time of design.
Further, the gap 8 provided between the side wall refractory 3 and the ceiling refractory 4 is designed so that the side wall refractory 3 takes into consideration the height direction thermal expansion amount of the side wall refractory 3 and the thickness direction thermal expansion amount of the ceiling refractory 4. The minimum thickness is often set so that the object 3 and the ceiling refractory 4 do not come into contact with each other. This is because the heating efficiency of the atmosphere furnace deteriorates when the gap 8 is excessively increased. Even if a filler such as a ceramic fiber is inserted into the gap 8, the furnace temperature is high, so that it is quite difficult to achieve sufficient sealing performance.

On the other hand, it must be considered that unexpected thermal expansion occurs even when the gap 8 is provided in consideration of the thermal expansion amount of the refractory used. Otherwise, the side wall refractory 3 and the ceiling refractory 4 are in contact with each other, and there is a risk of causing a damage trouble that causes a large crack in the ceiling refractory 4 as shown in FIG.
Therefore, in the atmosphere furnace described with reference to FIGS. 1 and 2, a rectangular frame support metal 13 is provided below each support beam 2. The rectangular frame support metal 13 is placed on the flange portion of each support beam 2 whose frame upper portion 13a is H-shaped steel.

  In FIG. 2, reference numeral 14 denotes an in-frame space of the frame support hardware 13. As shown in FIG. 1, the frame support metal fitting 13 was provided at both ends in the furnace width direction and at the bottom of the three support beams 2 in the center when the furnace ceiling was constructed. And after inserting the long pipe material 12 in the frame internal space 14 of the frame support metal fitting 13, the frame lower part 13b and the lower pipe material 12 were made to contact. In this way, the lower tube 12 is fixed to the support beam 2 by the frame upper portion 13a, and is inserted into the frame inner space 14 of the rectangular frame support hardware 13 when viewed in the longitudinal section of the support beam. It is preferable that the atmosphere furnace has a suspended ceiling structure in contact with the lower body portion 13b and held in the frame of the rectangular frame support metal 13.

  The reason for this is that even when the gap 8 taking into account the amount of thermal expansion of the refractory to be used is provided, unexpected thermal expansion may occur. In this case, the side wall refractory 3 and the ceiling refractory 4 are in contact with each other. Thus, when the ceiling refractory 4 is pushed up by the side wall refractory 3, the upper pipe member 6 is disposed below the support beam 2 out of the lower two pipe members 6 and 12, and arranged above each other. He who can rise to a position.

For this reason, a large crack arises in the ceiling refractory 4 and the risk of a major trouble can be reduced. Furthermore, since the frame upper portion 13a of the frame support metal 13 is on the flange portion of the support beam 2 that is H-shaped steel, the distance between the flanges of the support beam 2 that is H-shaped steel is the clearance. Become.
When heating a steel material in the atmosphere furnace described above, the furnace temperature is generally 1300 ° C. or higher. Therefore, when building the furnace ceiling of the atmospheric furnace for heating the steel material, the thickness of the ceiling refractory 4 is such that the heat dissipation is suppressed and the strength of the ceiling hanger is strong, and the steel frame comprising the support column 1 and the support beam 2 as structural members. From the critical temperature, it is usually preferred to be 300 mm or more. In the atmosphere furnace having such a suspended ceiling structure, the steel material can be heated under stable atmosphere conditions even if some temperature deviation in the furnace occurs.

The present invention was applied to a rotary hearth type rotary furnace having a ring-shaped furnace ceiling. In this rotary hearth type rotary furnace, an iron oxide agglomerate containing a reducing agent is placed on the hearth under reducing atmosphere conditions, and heated at a maximum temperature of 1550 ° C. while rotating the hearth. Used when producing agglomerates.
Dimensions of rotary hearth type rotary furnace hearth diameter: 10m, furnace width: 2m,
Ceiling span when building the furnace ceiling (in the case of the ring-shaped furnace ceiling 16 shown in FIG. 10, the interval measured at the center in the furnace width direction): 3 m .

As for the arrangement of the anchor bricks 5, when constructing the furnace ceiling, the pitch was set to 300 mm in the furnace width direction and the staggered arrangement in the furnace circumferential direction. High-alumina castables were used for the amorphous refractories. The gap 8 provided between the side wall refractory 3 and the ceiling refractory 4 was determined appropriately.
The following members were used for the ceiling hanging hardware.
Anchor brick hanging hardware: Round steel with a diameter of 9 mm.

Upper pipe: Carbon steel pipe for pressure piping with a diameter of 50A (JlS G3454 STPG sch40).
Lower pipe: Carbon steel pipe for pressure piping having a diameter of 65A.
Frame support metal: General structural rolled steel (JlS G3101 SS400).
In the inspection after operating the rotary hearth-type rotary furnace to which the present invention is applied and operating for one year, there are fine cracks in the side wall refractories and the ceiling refractories, but there are no troubles such as large cracks and ceiling dropouts, The ceiling refractory was in very good condition.

  In the case of the conventional ceiling suspended structure (corresponding to FIG. 3), there has been a refractory damage trouble in which a partial dropout or the like occurs in the ceiling refractory in 3 to 5 months after operation. As for the economic effect, not only the reduction of repair costs, but also the effect of improving the operating rate by extending the life of the furnace refractory and extending the life of the ceiling hanger is extremely large.

The present invention was applied to an atmosphere heating furnace having a rectangular furnace ceiling. This atmospheric heating furnace is used when heating a steel material at a maximum temperature of 1350 ° C. under non-oxidizing atmospheric conditions.
Dimensions of this atmosphere heating furnace Furnace length: 10 m, furnace width: 5 m,
Ceiling span when building the furnace ceiling (in the case of the rectangular furnace ceiling 15 shown in FIG. 9, where the amorphous refractory is poured when building the furnace ceiling): (2 m).

The anchor bricks 5 were arranged at a pitch of 350 mm in the furnace width direction and in a staggered arrangement in the furnace length direction when building the furnace ceiling. An alumina-silica castable was used for the irregular refractory. The gap 8 provided between the side wall refractory 3 and the ceiling refractory 4 was determined appropriately.
The following members were used for the ceiling hanging hardware.
Anchor brick hanging hardware: Round steel with a diameter of 9 mm.

Upper pipe: Carbon steel pipe for pressure piping with a diameter of 75A (JlS G3454 STPG sch80).
Lower pipe: Carbon steel pipe for pressure piping with a diameter of 100A.
Frame support metal: General structural rolled steel (JlS G3101 SS400).
In the inspection after operating the atmosphere heating furnace to which the present invention is applied and operating for one year, the side wall refractory and the ceiling refractory have fine cracks, but there are no troubles such as large cracks and dropouts. Was in a very good state.

  On the other hand, in the case of the conventional ceiling suspension structure (corresponding to FIG. 3), there has been a refractory damage trouble that causes partial dropout of the ceiling refractory in 3 to 5 months after operation, so the present invention was applied. The economic effect of this is not limited to the reduction of repair costs, but the effect of improving the operating degree by extending the life of the furnace refractory and extending the life of the ceiling hanger is extremely large.

(A) is an upper part sectional view showing the ceiling hanging structure of the atmosphere furnace concerning an embodiment of the invention, and (b) is a fragmentary sectional view showing the principal part. It is BB sectional drawing of FIG. It is upper part sectional drawing which shows the ceiling suspension structure of the conventional general atmosphere furnace. It is AA sectional drawing of FIG. It is an upper section showing the expansion direction of the refractory of the conventional general atmosphere furnace. It is upper part sectional drawing which shows the trouble which arises in the ceiling refractory of the conventional general atmosphere furnace. 3 is a partial cross-sectional view showing a ceiling suspension structure of an atmosphere furnace described in Patent Document 2. (A) is a front view viewed from a direction perpendicular to the pipe axis direction, (b) is a CC cross-sectional view, and (c) is a cross-sectional view of the main part. is there. It is a top view which shows the rectangular furnace ceiling of an atmospheric furnace. It is a top view which shows the ring-shaped furnace ceiling of an atmospheric furnace.

Explanation of symbols

1 Support 2 Support beam 3 Side wall refractory 4 Ceiling refractory 5 Anchor brick 6 Pipe (ceiling hanging hardware)
7 Anchor brick hanging hardware (ceiling hanging hardware)
8 Clearance 9 Large crack 10 Anchor brick neck 11 Shaped steel ceiling hanger 12 Tube material (ceiling hanger)
13 Frame support hardware (ceiling hanging hardware)
13a Frame upper part 13b Frame lower part 14 In-frame space 15 Rectangular furnace ceiling 16 Ring furnace ceiling O Center of rotation of hearth

Claims (3)

  In the suspended ceiling structure of the atmosphere furnace in which the ceiling refractory is supported by a plurality of support beams, the upper two lower tubes intersect with each other below the support beams and above the ceiling refractory. A suspended ceiling structure for an atmospheric furnace, wherein an anchor brick hanging hardware that suspends the ceiling refractory is hooked on the upper pipe member via a plurality of anchor bricks.   The suspended ceiling structure of an atmosphere furnace according to claim 1, wherein both the upper and lower two-stage pipe materials are steel pipes having a circular outer shape.   The lower tube is inserted into the frame space of the rectangular frame support metal provided on the support beam, and is held in the frame of the rectangular frame support metal by contacting the lower part of the frame. The suspended ceiling structure of an atmosphere furnace according to claim 1 or 2, wherein the suspended ceiling structure is an atmosphere furnace.

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