JP2001330209A - Radiant tube supporting structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a radiant tube supporting structure which can prolong the service life of a radiant tube by preventing the buckling and deformation of the whole body of the tube by significantly relieving the thermal stress and deformation of the tube and, at the same time, can be manufactured at a low cost. SOLUTION: This radiant tube supporting structure which supports a U- or W-type radiant tube is constituted in such a way that a supporting member is attached to the front end of the bend of the radiant tube positioned on the furnace wall side facing a radiant tube attaching wall and supporting metallic parts formed of a supporting piece provided along the furnace wall and a supporting arm crossing the supporting piece at right angles are buried in the stretchable refractory material of the furnace wall lined with the refractory material. In addition, the front end of the bend of the radiant tube is supported by the supporting arm of the supporting metallic parts and the lower end section of the supporting piece of the metallic parts is supported by a supporting block fixed to the furnace wall. Moreover, the upper end section of the supporting piece is engaged with a movable bolt which is passed through the furnace wall and to which a spring force is applied. The supporting metallic parts are made to be freely tiltable inside the furnace around the supporting block.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a support structure for a radiant tube having at least one or more bends, such as a continuous annealing furnace, a heating furnace for continuous galvanizing, and a U-shaped and W-shaped used in a soaking furnace. It is about.

[0002]

2. Description of the Related Art The structure of a W-shaped radiant tube installed in a typical conventional vertical furnace is shown in FIG. In the radiant tube 1, the burner side end 2 and the exhaust gas side end 10 having the recuperator 18 are both welded to a bank 14 in order to prevent air from entering the furnace. It is welded to the wall 15-1 and fixed respectively. In the furnace, the support member 13 at the tip of the third bend 8 is attached to the mounting wall 1 of the radiant tube 1.
5-1 and a lower part of the first bend 4 or the second straight pipe 5 and a third bend 8 or the third straight pipe 7 Saddle 11 between the upper part of
Alternatively, a saddle 12 is provided between the lower part of the third straight pipe 7 and the upper part of the fourth straight pipe 9.

By the way, the radiant tube 1 is restricted by the above-mentioned support and mounting structure against thermal expansion due to high-temperature heating, and thermal stress and deformation occur. Cracks and deformations that come into contact with the strips occur, rendering them unusable and need to be replaced each time. This thermal stress and deformation will be described in more detail with reference to FIGS.

FIG. 9 shows an example of a radiant tube temperature distribution during normal operation. As shown in this figure, the radiant tube has a temperature gradient falling from the burner side to the exhaust gas side, and the average temperature difference between the first straight pipe and the fourth straight pipe is about 5
It is about 0 to 100 ° C. This temperature gradient causes a difference in the amount of thermal expansion among the first straight pipe, the second straight pipe, the third straight pipe, and the fourth straight pipe. In particular, the influence of the difference in thermal expansion between the first straight pipe and the fourth straight pipe. Thus, the radiant tube tends to deform vertically downward in addition to the thermal expansion in the axial direction.

FIG. 10 (A) shows the thermal deformation in the radiant tube temperature distribution of FIG. 9 calculated by the deflection angle method under the condition that the third bend tip support member 13 is not provided, assuming that the weight of the radiant tube 1 is zero. In the thermal deformation mode diagram obtained in (1), the expansion amount in the axial direction 28 is magnified 5 times and the expansion amount in the vertical direction 29 is magnified 10 times. It is assumed that the radiant tube has a coefficient of thermal expansion of 17 × 10 ⁻⁶ / ° C. The amount of thermal expansion at the center of the tip of the third bend 8 under this condition is: axial thermal expansion (dX ₁ ): 38 mm Vertical downward thermal expansion (dY ₁ ): 6 mm

As shown in this figure, the radiant tube 1
Is greatly affected by the difference in the amount of expansion between the first straight pipe 3 and the fourth straight pipe 9 in the axial direction 28, and this difference in the amount of expansion is
The end of the radiant tube 1 is to be absorbed vertically by the same principle as that of the bimetal.
Try to transform to However, actually, the third bend 8 is formed by the third bend tip support member 13 and the furnace wall support bracket 16.
10B is restrained, the third bend 8 is in the same state as when the third bend 8 is forcibly displaced in the vertical upward direction 29 by dY from the state of the shape 2 in FIG. 10A. )
Of the shape 3.

As a result, a large fulcrum reaction force 30 is applied to the third bend tip support member 13 from the furnace wall support bracket 16, and a large bending moment 31 is applied to the third bend tip support member 13.
Then, a compressive force 33 is generated in the first straight pipe 3 and the third straight pipe 7, and a tensile force 32 is generated in the second straight pipe 5 and the fourth straight pipe 9. Further, the lower portion of the first bend 4 and the second
A vertical upward load 34 is generated near the saddle 11 of the straight pipe 5, and a vertical downward load 35 is generated above the third bend 8 and near the saddle 11 of the third straight pipe 7.

Next, the deformation of the radiant tube due to thermal expansion when the temperature is raised will be described. In order to repair the furnace, the temperature of the furnace is repeatedly raised and lowered periodically. In particular, when the temperature of the furnace is raised from the normal temperature to the normal operation state, the temperature of the first straight pipe 3 rapidly rises due to the combustion of the burner 17. However, the temperature difference from the portion after the first bend 4 greatly increases. This temperature difference between the first straight pipe 3 and the fourth straight pipe 9 may instantaneously reach several hundred degrees Celsius.

For example, the representative temperature of each straight pipe from the first straight pipe to the fourth straight pipe of the radiant tube is set to 700 ° C. and 500 ° C.
FIG. 11 shows a morphological diagram of the deformation of the radiant tube due to thermal expansion at the time of temperature rise, which was also obtained at 400 ° C., 400 ° C., and 300 ° C.
Shown in Here, FIG. 11A is a thermal deformation diagram obtained by assuming that the weight of the radiant tube 1 is zero under the condition that there is no third bend tip support member 13 as in FIG. 10A, and FIG. 10) is a modified form diagram obtained under the condition that the vertical downward displacement of the tip of the third bend 8 is restrained by the third bend tip support member 13 and the furnace wall support hardware 16 as in FIG.

The third bend 8 under the condition of FIG.
The calculation result of the thermal expansion amount at the center of the front end is: axial thermal expansion amount (dX ₂ ): 15 mm vertical downward thermal expansion amount (dY ₂ ): 35 mm. It can be seen that the deformation amount is larger than the deformation amount. As described above, since the average deformation temperature of the radiant tube 1 at the time of heating the furnace is low in addition to the deformation amount being larger than that in the normal operation, the longitudinal elastic coefficient of the tube material is larger than that in the normal operation. 13, the compressive stress 33 applied to the first straight pipe 3 and the third straight pipe 7, the tensile stress 32 applied to the second straight pipe 5 and the fourth straight pipe 9, and the first bend 4 through the saddle 11. Further, the upward load 34 applied to the vicinity of the saddle 11 of the second straight pipe 5 and the downward load 35 applied to the vicinity of the saddle 11 of the third bend 8 and the third straight pipe 7 are further increased as compared with the normal operation.

FIG. 12 shows a damage form at the end stage of a radiant tube by a conventional support structure. Blister 36 of first straight pipe 3 due to internal compressive stress of first straight pipe, first straight pipe 3
Buckling of the upper part of the saddle 11 due to the vertical upward load 34 applied through the saddle 11, and the saddle 11
Buckling 38 of the lower part of the saddle 11 due to a vertical downward load 35 applied through the shaft, rotational deformation 39 of the third bend tip support member 13 due to the fulcrum reaction force 30, and third tip 8 tip seat due to the third bend 8 tip bending moment 31. Refraction 40 and the like occur. The radiant tube 1 is exposed to a high temperature for a long time, and undergoes creep deformation due to the above-mentioned stress and the influence of its own weight. -The crack 41 near the buckling leads to the end of the service life of the radiant tube.

As described above, the radiant tube is constrained by the support fitting from the furnace wall, the saddle between the tubes, and the rigidity of the tube itself, and the bending moment and the tension / compression inside the straight tube during temperature rise and normal operation. It is greatly affected by stress. Therefore, reducing the binding force extends the life of the radiant tube. As means for preventing this deformation and cracking, Japanese Patent Application Laid-Open No. 5-272708 discloses a structure in which a bellows for absorbing the axial elongation of a burner-side straight pipe is attached to a burner-side end. Japanese Patent No. 38415 discloses a structure having a bellows at the burner side end in the axial direction of the tube to make thermal expansion free. Further, Japanese Patent Application Laid-Open No. 10-324915
In the publication, a structure is disclosed in which a support member of a radiant tube is projected outside a furnace, the support member is supported outside the furnace, and a flexible seal is attached to a portion where the support member penetrates a furnace wall.

[0013]

However, in the structures disclosed in JP-A-5-272708 and JP-A-1-38415, although the bellows is effective in relieving stress, the installation of the bellows increases costs. There was also a problem with the durability of the bellows. Also, Japanese Unexamined Patent Publication No.
In the structure disclosed in Japanese Patent Application Laid-Open No. 08-324915 and the structure disclosed in Japanese Patent Application Laid-Open No. H10-324915, it is not possible to absorb the vertical downward bending of the tube tip caused by the temperature difference between the burner side and the exhaust gas side of the tube. There were problems with improving.

The present invention has been proposed in order to solve the above-mentioned problems, and significantly reduces the thermal stress and deformation of the radiant tube during normal operation and even during temperature rise, thereby reducing the first straight pipe. The buckling of the entire tube is prevented by preventing the buckling of the radiant tube, thereby providing an excellent effect of extending the life of the radiant tube and providing a low-cost radiant tube support structure.

[0015]

A radiant tube support structure in which a burner side end of a radiant tube having at least one or more bends and an exhaust gas side end are attached to the same furnace wall side, Attach a support member to the bend end of the radiant tube located on the furnace wall side facing the mounting wall of the radiant tube,
Further, a support piece provided along the furnace wall and a support arm orthogonal to the support piece form a support fitting, and the support fitting is embedded in a refractory material of a furnace wall lined with a stretchable refractory material,
The support arm of the support fitting supports the support member at the tip of the bend of the radiant tube. On the other hand, the lower end of the support piece of the support fitting is supported by a support block fixed to the furnace wall, and the upper end is the furnace wall. The support fitting is configured to be tiltable inward of the furnace with the support block serving as a fulcrum by being configured to engage with a movable bolt to which a spring force is applied through the support bolt. Further, the upper end of the support piece constituting the support fitting is engaged with one end of a bolt penetrating the furnace wall, and the other end of the bolt is outside the furnace, externally covers a spring, and is fixed via a nut. And a portion located outside the furnace is covered with a seal box.

[0016]

Embodiments of the present invention will be described below.
FIG. 1 is a drawing illustrating an example of a support structure of a radiant tube of the present invention, and FIG.
FIG. 2A is a transverse sectional view, and FIG. 2B is a longitudinal sectional view.
The radiant tube 1 is used, for example, in a continuous annealing furnace, and is a W-shaped radiant tube.
It comprises a second straight pipe 5, a third straight pipe 7, a fourth straight pipe 9, and a first bend 4, a second bend 6, and a third bend 8 connecting the straight pipes. In this embodiment, the first straight pipe 3 and the fourth straight pipe 3
The length of the straight pipe 9 is 2250 mm, the length of the second straight pipe 5 and the third straight pipe 7 is 1500 mm, and the distance between the axes of each straight pipe is 3
00 mm. Outer diameter and inner diameter are 194mm and 1 respectively
77 mm, the material is SCH22 of JIS G5122.

Further, the burner side end 2, the exhaust gas side end 10 and the bank 14 of the radiant tube 1 are fixed by welding as in the prior art, and the internal support structure between the tubes is also the same as in the prior art. Internal support structure, and a saddle 11 is provided below the second straight pipe 5 and above the third straight pipe 7.
However, saddles 12 are provided between the lower part of the third straight pipe 7 and the upper part of the fourth straight pipe 9, respectively. 17 is a burner, 1
8 is a recuperator and 19 is an exhaust gas outlet.

As shown in FIG. 1, a W-shaped radiant tube 1 has a burner side end 2 and an exhaust gas side end 10 attached to the same furnace wall 15-1 side. Furnace wall 15-2 opposed to furnace wall 15-1
The third bend tip support member 13 is attached to the center of the tip of the third bend 8 of the radiant tube 1 located on the side. Further, the support fitting 16 for supporting the third bend tip support member 13 has a shape having a right angle portion. Specifically, a support piece 50 provided along the furnace wall 15-2 and a support piece 50 orthogonal to the support piece 50 are provided. And a support arm 49 that supports the third bend tip support member 13 of the radiant tube 1. In this embodiment, the support arm 49 extends horizontally from the lower end of the support piece 50 toward the inside of the furnace. The support bracket 16 is embedded in a refractory material 20 lining the furnace wall 15-2.
For example, it is a ceramic fiber blanket.

In the case of this embodiment, the supporting bracket 16 has a triangular longitudinal sectional view as shown in FIG. 2B, and a right angle portion of the supporting bracket 16, that is, the supporting piece 5 of the supporting bracket 16 is provided.
The lower end of 0 is supported by a support block 21 fixed to the furnace wall 15-2 in order to support a load in a vertically downward direction. Further, the upper end of the support piece 50 forming the support fitting 16 penetrates through the furnace wall 15-2 and is engaged with the movable bolt 23 to which a spring force is applied. This furnace wall 15-2
The bolt 23 covers the spring 22 on the outside of the furnace of the bolt 23 that penetrates through, and the support bracket 16 is connected to the spring 22 by the bolt 23, the washer 24 and the nut 25. Here, the washer 24 is provided, but a nut with a washer may be used as a matter of course. With such a configuration, the support bracket 16 can be tilted inward of the furnace with the support block 21 as a fulcrum.

Further, a portion located outside the furnace is covered with a seal box. In this embodiment, the short pipe 26 is connected to the furnace wall 15-2 at a portion where the bolt 23 penetrates the furnace wall 15-2.
, The tip of the short pipe 26 is attached to the short pipe 26 with a cap 27 having a screw, the inside of the short pipe 26 is sealed, and the furnace wall penetration is sealed from outside the furnace. Also, the support arm 49
When the support bracket 16 is tilted vertically downward about the fulcrum 44, the support surface 45 of the third bend tip support member 13 due to the thermal expansion in the radiant tube axial direction has an axial direction 28.
The slope 46 is provided downward toward the furnace wall 15-2 so as not to hinder the movement of the furnace.

In this embodiment, in order to give strength to the support bracket 16, a support piece 50 for forming the support bracket 16 is used.
The upper end of the support arm 49 is connected to the support arm 49 by an inclined portion 51, and the support bracket 16 has a triangular cross section as shown in FIG. If the strength itself is provided, the inclined portion 51 may not be provided.
A support piece 50 provided at least along the furnace wall 15-2;
A support bracket 16 having a support arm 49 orthogonal to the support arm 49
With the support block 21 as a fulcrum,
The present invention can be implemented as long as it is configured to tilt toward the inside of the furnace. The portion where the support piece 50 and the support arm 49 are orthogonal to each other may not necessarily have a perfect orthogonal shape but may have an angle slightly forward or backward. In order to increase the strength of the support bracket 16, an arm may be attached to a portion orthogonal to the support arm 49 and the support piece 50, or the inclined portion 51 of the support bracket 16 may be provided.
May be provided, and the inclined portions 51 may intersect to form the support bracket 16 so as to increase the strength.

In addition, a pin is passed through an orthogonal portion of the support bracket 16 instead of the support block 21, and the support bracket 16 is tilted inward of the furnace using this pin as a fulcrum, and both ends of the pin are connected to the furnace wall 15-.
2 may be supported. Further, FIG. 3 shows another embodiment of the present invention, FIG. 3-A is a detailed explanatory view of the support fitting (cross section), and FIG. 3-B is a detailed explanatory view of the support fitting (longitudinal section). . In this embodiment, the support arm 49 extends from the upper end of the support piece 50 toward the inside of the furnace. Then, the tip of the support arm 49 and the lower end of the support piece 50 are
The connecting support bracket 16 is formed by the inclined portion 51. Others are the same as the above-mentioned embodiment. The mounting position of the support arm 49 may be slightly lower than the upper end of the support piece 50 or slightly higher than the lower end.

The support bracket 16 of the present invention having the above-described configuration can be tilted about the fulcrum 44 on the upper surface of the support block 21, so that the load received from the radiant tube third bend tip support member 13 and the spring 22 is fixed at an arbitrary position where the reaction force is balanced. Before the temperature rise of the radiant tube without thermal deformation, the support bracket 16 sets the initial setting length 43 of the spring so that the third bend tip support member 13 of the radiant tube 1 receives about 40% of the weight of the radiant tube 1. It is set by adjusting the position of the nut 25.

When the third bend support member 13 is displaced vertically downward by the vertical downward thermal expansion amount dY ₁ at the center of the third bend tip during normal operation, and when the furnace temperature rises, the thermal expansion amount dY
When the third bend support member 13 is displaced vertically downward by Y ₂ , the spring 22 contracts between the furnace wall 15-2 and the washer 24, and the support bracket 16 moves the support surface 45 about the fulcrum 44 to dY _1. Alternatively, it tilts by an angle corresponding to the displacement of dY ₂ and follows the vertical displacement of the support member 13.

FIG. 4 shows a state in which the support bracket 16 is tilted, and FIG. The spring 22 preferably satisfies the following conditions so as not to apply excessive stress to the radiant tube 1. (1) Radiant tube third bend tip support member 13
When the support bracket 16 is tilted due to the vertical maximum thermal deformation dY ₂ of the radiant tube 1, the support bracket 16 applies a vertical fulcrum reaction force exerted on the third bend tip support member 13 by the reaction force of the spring due to the reaction force of the spring. W or less.

(2) When the support member 16 is tilted by the vertical downward thermal deformation dY ₁ of the third bend tip support member 13 during normal operation, the support bend 16 is moved by the reaction force of the spring. 13 is approximately の of the total load W of the radiant tube 1.
And This is because it is most preferable to extend the life of the radiant tube by setting the most appropriate supporting load during normal operation, which is the longest period during the operation period of the radiant tube, and to apply a rotational moment to the radiant tube in this structure. This is because the supporting load not applied is about 1/2 of the total weight of the radiant tube. The total weight of the radiant tube 1 is about 350 kg,
The distance 47 from the fulcrum 44 to the support surface and the distance 48 from the fulcrum 44 to the spring 22 were equal to 350 mm. Also, two springs 22 are provided for one support fitting.

The vertical downward thermal expansion of the third bend tip support member 13 is maximum when the furnace is heated, the vertical vertical maximum thermal expansion dY ₂ is 35 mm, and the vertical downward thermal expansion during normal operation. dY ₁ is expected to be 6 mm. Therefore, a spring that satisfies the following equation is selected. k (dL ₁ + dL) = W / 2 / n (1) k (dL ₂ + dL) = W / n (2) where k (kg / mm): spring constant dL (mm): initial deflection amount of the spring _{dL = L 0 -L L 0 (} mm): free length of the spring L (mm): initialization length dL ₁ of the spring (mm): vertical thermal expansion amount of the normal third bend support receiving portion during operation dY ₁ The amount of deflection dL ₂ (mm) from the initial set length of the spring corresponding to the following: The amount of deflection W (Kg) from the initial set length of the spring corresponding to the maximum vertical thermal expansion amount dY ₂ of the third bend support receiving portion: Radiant tube weight n: Number of springs per support hardware

In the present embodiment, W is 350 kg, and dL ₁ is dY ₁ because the distance 47 from the fulcrum 44 to the support surface of the support metal is equal to the distance 48 from the fulcrum 44 to the spring 22.
= DL ₁ = 6 mm, dY ₂ = dL ₂ = 35 mm, n = 2
It is. From the equations (1) and (2), the spring constant k =
3.0 Kg / mm and initial spring deflection dL = 23
mm is obtained. From the above, the spring constant k = 3.0 Kg / m
m, a spring diameter of 65 mm, a spring wire diameter of 9 mm, a free length L _{0 of the} spring = 170 mm, and a compression coil spring having a maximum deflection of 60 mm are selected.

Accordingly, the fulcrum load applied to the third bend tip support member 13 by the support fitting 16 is R _{1 for} the fulcrum load at the time of initial setting, R _{2 for} the fulcrum load during normal operation, and R ₃ for the fulcrum load during furnace heating. Then, R ₁ = k × dL × n = 138 kg R ₂ = k × (dL + dL ₁ ) × n = 174 kg R ₃ = k × (dL + dL ₂ ) × n = 348 kg.

FIGS. 6 and 7 show a comparison of the axial stress of the radiant tube using the support fitting according to the present invention and the support fitting having the conventional structure. In the support bracket according to the present invention, the compressive stress of the first and third straight pipes and the tensile stress of the second and fourth straight pipes, which are remarkable in the conventional structure, become substantially zero,
It can be seen that the internal stress of the radiant tube is greatly improved. FIG. 6 shows a calculation result based on the above-described tube surface temperature condition at the time of normal operation, and FIG. 7 shows a calculation result at the time of furnace temperature rise.

The radiant tube support structure according to the present invention makes it possible to absorb the vertical downward bending of the tube tip caused by the temperature difference between the radiant tube on the burner side and the exhaust gas side. Can be greatly extended.
In this embodiment, the case where the invention is applied to a vertical furnace is described as an example. However, the case where a radiant tube is installed in a horizontal furnace is naturally applicable. In this embodiment, the case where the third bend of the W-shaped radiant tube is supported has been described, but the first bend may be supported together.

[0032]

As described above, the present invention relates to a support fitting for supporting a radiant tube attached to a furnace wall from the furnace wall such that the burner side end and the exhaust gas side end of the tube are positioned vertically. One end is supported from the furnace wall via a spring, and a support structure capable of absorbing the vertical downward bending of the radiant tube restrains the thermal expansion of the radiant tube at the time of temperature rise and during normal operation. Without bulging and buckling, buckling of the saddle up and down, and buckling of the third bend tip support receiving part. This prevents buckling and deformation of the entire tube, stabilizes the support of the radiant tube and extends its life, and keeps the cost stable and ensures stable operation. Or the like which is superior effect.

[Brief description of the drawings]

FIG. 1 is a drawing showing an embodiment of the present invention.

FIG. 2 is a detailed explanatory drawing (transverse section and longitudinal section) of a support structure portion according to the embodiment of the present invention.

FIG. 3 is a detailed explanatory view (transverse section and longitudinal section) of a support fitting according to another embodiment of the present invention.

FIG. 4 is a view illustrating a state in which a support bracket of the present invention is tilted.

FIG. 5 is a partial detailed drawing of FIG. 4;

FIG. 6 is a view showing a calculation result of an axial stress of a radiant tube based on a measurement result of a radiant tube surface temperature from a burner side end in a combustion test.

FIG. 7 is a drawing showing a result of a trial calculation of an axial stress of a radiant tube at an assumed value of a radiant tube surface temperature at the time of temperature rise.

FIG. 8 is an explanatory view of a W-shaped radiant tube having a conventional support structure.

FIG. 9 is a view showing a measurement result of a radiant tube surface temperature from a burner side end in a combustion test.

FIG. 10 is a diagram showing a form of deformation of a radiant tube due to thermal expansion during normal operation.

FIG. 11 is a diagram showing a form of deformation of the radiant tube due to thermal expansion when the temperature is raised.

FIG. 12 is an explanatory diagram of a damage mode at the end of a W-shaped radiant tube using a conventional support structure.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Radiant tube 2 Burner side end part of radiant tube 3 1st straight pipe 4 1st bend 5 2nd straight pipe 6 2nd bend 7 3rd straight pipe 8 3rd bend 9 4th straight pipe 10 Exhaust side end of radiant tube Part 11 Saddle between radiant tubes 12 Saddle between radiant tubes 13 Third bend tip support member 14 Bank 15-1, 15-2 Furnace wall 16 Support fitting 17 Burner 18 Recuperator 19 Exhaust gas outlet 20 Refractory 21 Support block 22 Spring 23 Bolt 24 Washer 25 Nut 26 Short pipe 27 Cap 28 Axial direction 29 Vertical direction 30 Support point reaction force 31 Bending moment 32 Axial tensile force 33 Axial compressive force 34 Vertical upward load 35 Vertical downward load 36 First straight pipe bulge 37 Saddle Upper straight tube buckling 38 Saddle lower straight tube buckling 3 9 Rotational deformation of third bend tip support receiving part 40 Third bend tip buckling 41 Crack 42 Buckling of first straight pipe 43 Initial setting length of spring (L) 44 Support point 45 Supporting hardware support surface 46 Slope 47 Supporting hardware Distance from fulcrum 44 to support surface 48 Distance from fulcrum of support hardware to spring 22 49 Support arm 50 Support piece 51 Inclined part

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Hiroshi Noda 59-46 Nakahara, Tobata-ku, Kitakyushu-shi, Fukuoka F-term in Nittetsu Plant Design Co., Ltd. 3K017 BB09 BC01 BE00 3K091 AA18 AA20 BB05 BB04 BB25 EA04 EA14 EA15 EA22 EA29

Claims (2)

[Claims] 1. A radiant tube support structure wherein a burner side end of a radiant tube having at least one or more bends and an exhaust gas side end are attached to the same furnace wall side. A support member is attached to the bend end of the radiant tube located on the furnace wall side opposite to the mounting wall, and further, a support bracket is formed by a support piece provided along the furnace wall and a support arm orthogonal to the support piece. The support fitting is embedded in a refractory material of a furnace wall lined with a stretchable refractory material, and a support member at a bend end of the radiant tube is supported by a support arm of the support fitting. The lower end of the support piece is supported by a support block fixed to the furnace wall, and the upper end is configured to engage with a movable bolt that penetrates the furnace wall and has a spring force applied thereto. Thus, the support fitting can be tilted inward of the furnace with the support block as a fulcrum. 2. An upper end portion of a support piece constituting the support fitting is engaged with one end of a bolt penetrating a furnace wall, the other end of the bolt is outside the furnace, and a spring is sheathed. The support structure for a radiant tube according to claim 1, wherein a portion positioned outside the furnace is fixed by a seal box.