JP6908018B2 - In-core support structure for W-type radiant tube - Google Patents

Description

The present invention relates to an in-furnace support structure that supports a W-type radiant tube used in an industrial heating furnace in the furnace.

Conventionally, a burner using a radiant tube (radiant tube burner) is often installed as a heating device for a metal band or the like in an industrial heating furnace (for example, Patent Document 1).

Here, a radiant tube burner using a W-shaped radiant tube is targeted, and a typical example thereof is shown in FIG.

As shown in FIG. 4, the W-shaped radiant tube (hereinafter, also simply referred to as “radiant tube”) 1 used in this radiant tube burner has four straight pipes having a circular cross section (first straight pipe 2, first straight pipe 2, first). 2 Straight pipe 3, 3rd straight pipe 4, 4th straight pipe 5) and 3 curved pipes with a circular cross section (1st curved pipe 6, 2nd curved pipe 7, 3rd curved pipe 8) It has become.

Then, the radiant tube 1 is installed in the heating furnace so that the side surfaces of the straight pipes 2 to 5 face the surface of the material to be heated (not shown) such as a metal band running in the heating furnace in the vertical direction. Is located in. The combustion gas 9 injected from the burner (burner main body) installed on the furnace wall 11b passes through the inside of the radiant tube 1 and is discharged to the outside of the system as exhaust gas 10.

In other words, from the top to the bottom, the first straight pipe 2, the first curved pipe 6, the second straight pipe 3, the second curved pipe 7, the third straight pipe 4, the third curved pipe 8, the fourth straight pipe. The pipe 5 is provided, the first straight pipe 2 is located on the burner side, and the fourth straight pipe 5 is located on the exhaust gas side.

At that time, the combustion gas 9 may be operated at an extremely high temperature of 1000 ° C. or higher, and therefore each of the tubes 2 to 8 of the radiant tube 1 is thermally expanded in the tube axis direction. Therefore, the radiant tube 1 is supported by the metal fitting 12 installed on the furnace wall 11a and the third curved pipe support 13 provided on the third curved pipe 8, and the metal fitting 12 and the third curved pipe support 13 are supported. By sliding the sliding portion 14 between the two by the above-mentioned thermal elongation, the radiant tube 1 has a structure in which no thermal binding force is generated. Further, between the second straight pipe 3 and the third straight pipe 4, the load (own weight) of the upper straight pipe (first straight pipe 2, second straight pipe 3) is applied to the lower straight pipe (third straight pipe 4). , A load delivery member 17 for delivering to the fourth straight pipe 5) is installed.

However, the radiant tube 1 as described above has a problem that the straight pipes 2 to 5 hang down due to a bending load. That is, since the gas temperature in the radiant tube 1 becomes lower toward the downstream in the gas flow direction, the straight pipes 2, 3, 4, and 5 do not expand equally, so that the entire radiant tube 1 is distorted and the bending load is applied. It acts and the straight pipes 2 to 5 will hang down. If the drooping of such a straight pipe becomes large, the hanging fourth straight pipe comes into contact with the first straight pipe of the radiant tube adjacent to the lower side of the radiant tube, which causes damage to the radiant tube and operation trouble. ..

To solve this problem, a radiant tube having an elliptical cross-sectional shape has been proposed (for example, Patent Document 2). The elliptical shape of the cross section has a long axis in the vertical direction (running direction of the material to be heated). As described above, by using the straight pipe having an elliptical cross section, the cross-sectional performance is improved as compared with the straight pipes 2 to 5 having a circular cross section, so that the sagging due to the bending load can be reduced.

In addition, recently, the demand for high performance and high quality for industrial products has become stronger, and the heating conditions in industrial heating furnaces have become stricter, so that the heat load of the radiant tube has become more and more large. Therefore, in Patent Document 3, a reinforcing material for preventing bending is arranged inside a straight pipe having an elliptical cross section to increase the strength and the life of the radiant tube.

Japanese Unexamined Patent Publication No. 9-303711 Japanese Unexamined Patent Publication No. 5-285533 Japanese Unexamined Patent Publication No. 2016-161221

The above-mentioned conventional technique has made it possible to suppress the sagging of the pipe due to insufficient strength of the radiant tube itself, but the weight of the radiant tube is increasing due to the elliptical cross section of the pipe and the installation of a reinforcing material inside the pipe. Therefore, if the in-core support structure of the radiant tube is not appropriate, there arises a problem that the pipe hangs down due to the in-core support structure.

Here, using the radiant tube burner shown in FIG. 4 as an example, FIG. 5 shows a state in which the pipe hangs down due to the in-furnace support structure.

As shown in FIG. 5, the third curved pipe support 13 provided in the third curved pipe 8 bends diagonally upward with the connection portion with the third curved pipe 8 as a starting point, warps and deforms upward, and has a support function. Is damaged, and the pipe (particularly the fourth straight pipe) hangs down.

As described above, when the hanging of the pipe (particularly the 4th straight pipe) becomes large, the hanging 4th straight pipe comes into contact with the 1st straight pipe of the radiant tube adjacent to the lower side of the radiant tube, and the radiant tube is damaged. And will cause operational troubles.

The present invention has been made in view of the above circumstances, and as an in-core support structure for a W-type radiant tube used in a radiant tube burner, the occurrence of pipe sagging due to the in-core support structure is suppressed. It is an object of the present invention to provide an in-core support structure for a W-type radiant tube, which enables a long life of the W-type radiant tube.

In order to solve the above problems, first, in the in-core support structure of the W-type radiant tube, the mechanism by which the third curved tube support 13 is warped and deformed as shown in FIG. 5 is examined.

As a result, as shown in FIG. 6, a rotational moment acts on the third curved tube support 13 due to the load received by the third curved tube 8 to the third curved tube support 13, and the third curved tube support 13 is warped upward. It was considered that the deformation had occurred. Here, this rotational moment is a rotational moment that rotates with the upper surface of the tip of the receiving metal fitting 12 in contact with the lower surface of the third curved tube support 13 as the rotation center 21 (in FIG. 6, the rotation rotates counterclockwise). Moment).

Therefore, in order to suppress the upward warp deformation of the third curved tube support 13, a rotational moment (rotational moment rotating counterclockwise) acting on the third curved tube support 13 due to the load from the third curved tube 8 is applied. , I thought that it should be canceled by the rotational moment that rotates in the opposite direction (rotational moment that rotates clockwise).

The present invention is based on the above idea and has the following features.

[1] The first straight pipe, the first curved pipe, the second straight pipe, the second curved pipe, the third straight pipe, the third curved pipe, and the fourth straight pipe are provided in this order from the upper side to the lower side. An in-core support structure for supporting a W-shaped radiant tube in which the first straight pipe is located on the burner side and the fourth straight pipe is located on the exhaust gas side.
The first curved pipe support installed on the first curved pipe, the third curved pipe support installed on the third curved pipe, and the metal fittings attached to the furnace wall to support the third curved pipe support. It has a connecting rod for connecting the first curved pipe support and the third curved pipe support.
The rotational moment acting on the third curved pipe support due to the load received from the third curved pipe by the third curved pipe support is applied to the third curved pipe support by the load received from the connecting rod by the third curved pipe support. An in-core support structure for a W-shaped radiant tube, which is characterized in that it is canceled by a rotational moment in the opposite direction in which it acts.

[2] The in-core support structure for a W-shaped radiant tube according to the above [1], which comprises a plurality of the connecting rods.

[3] The cross-sectional shapes of the first straight pipe, the second straight pipe, the third straight pipe, the fourth straight pipe, the first curved pipe, the second curved pipe, and the third curved pipe are The in-core support structure for a W-shaped radiant tube according to the above [1] or [2], which is characterized in that they all have the same elliptical shape.

According to the present invention, as the in-core support structure of the W-type radiant tube used for the radiant tube burner, it is possible to suppress the occurrence of pipe sagging due to the in-core support structure and extend the life of the W-type radiant tube. It is possible to obtain an in-core support structure for a W-shaped radiant tube.

It is a figure which shows Embodiment 1 of this invention. It is a figure which shows the action effect in Embodiment 1 of this invention. It is a figure which shows Embodiment 2 of this invention. It is a figure which shows the prior art. It is a figure which shows the occurrence of the sagging of a pipe due to the support structure in a furnace in the prior art. It is a figure which shows the mechanism which the hanging of a pipe occurs due to the support structure in a furnace in the prior art. It is a figure which shows the Example.

Embodiments of the present invention will be described with reference to the drawings.

[Embodiment 1]
FIG. 1 is a diagram showing the first embodiment of the present invention.

As shown in FIG. 1, the W-shaped radiant tube 1 according to the embodiment of the present invention has four straight pipes having a circular cross section (first straight pipe 2, first straight tube 2, second) similar to the W-shaped radiant tube 1 shown in FIG. 2 Straight pipe 3, 3rd straight pipe 4, 4th straight pipe 5) and 3 curved pipes with a circular cross section (1st curved pipe 6, 2nd curved pipe 7, 3rd curved pipe 8) It has become.

Then, the radiant tube 1 is installed in the heating furnace so that the side surfaces of the straight pipes 2 to 5 face the surface of the material to be heated (not shown) such as a metal band running in the heating furnace in the vertical direction. Is located in. The combustion gas 9 injected from the burner (burner main body) installed on the furnace wall 11b passes through the inside of the radiant tube 1 and is discharged to the outside of the system as exhaust gas 10.

In other words, from the top to the bottom, the first straight pipe 2, the first curved pipe 6, the second straight pipe 3, the second curved pipe 7, the third straight pipe 4, the third curved pipe 8, the fourth straight pipe. The pipe 5 is provided, the first straight pipe 2 is located on the burner side, and the fourth straight pipe 5 is located on the exhaust gas side.

Then, in the first embodiment, as the in-core support structure for supporting the W-shaped radiant tube 1 in the furnace, the first curved tube support 18 installed in the first curved tube 2 and the third curved tube support 18 are used. The third curved pipe support 13 installed on the pipe 8, the metal fitting 12 attached to the furnace wall 11a to support the third curved pipe support 13, and the first curved pipe support 18 and the third curved pipe support 12 It has a connecting rod 19 for connecting the spaces. Here, the pin 20a provided on the first curved pipe support 18 and the pin 20b provided on the third curved pipe support 13 are connected by a connecting rod 19 so that both ends form rotary joints of the pipe. It is designed to absorb thermal deformation.

As a result, in the first embodiment, the load received by the third curved pipe support 13 is first distributed from the third curved pipe 8 and from the connecting rod 19, so that the third curved pipe 8 to the third curved pipe support 13 are distributed. The load received by the tube and the resulting rotational moment are reduced. Then, as shown in FIG. 2, the rotational moment acting on the third curved tube support 13 due to the load received by the third curved tube 8 to the third curved tube support 13 is generated from the connecting rod 19 to the third curved tube support 13. Is canceled by the rotational moment in the opposite direction acting on the third curved pipe support 13 due to the load received by the pipe.

The rotational moment acting on the third curved tube support 13 due to the load received from the third curved tube 8 to the third curved tube support 13 is such that the upper surface of the tip of the receiving metal fitting 12 is in contact with the lower surface of the third curved tube support 13. It is a rotational moment (rotational moment that rotates counterclockwise in FIG. 2) that rotates with the location 21 as the center of rotation. On the other hand, the rotation moment in the reverse direction acting on the third curved pipe support 13 due to the load received from the connecting rod 19 to the third curved pipe support 13 is such that the upper surface of the tip of the receiving metal fitting 12 is the third curved pipe support 13. It is a rotational moment that rotates in the opposite direction with a portion in contact with the lower surface as the rotation center 21 (in FIG. 2, a rotational moment that rotates clockwise).

As a result, in the first embodiment, the warp deformation of the third curved pipe support 13 is suppressed, and the third curved pipe support 13 can be stably brought into contact with the receiving metal fitting 12, and the pipe (particularly). The sagging of the fourth straight pipe 5) is reduced, and the life of the W-shaped radiant tube 1 can be extended.

In FIG. 1, both ends of the connecting rod 19 are rotary joints in order to absorb the thermal deformation of the pipe, but in some cases, only one end of the connecting rod 19 is a rotary joint. May be good. Further, a rotary joint using a long hole may be used. Further, a roller may be provided between the third curved tube support 13 and the receiving metal fitting 12, or a heat-resistant paint may be applied.

[Embodiment 2]
FIG. 3 is a diagram showing a second embodiment of the present invention.

In the first embodiment of the present invention shown in FIG. 1 above, there is one connecting rod 19 that connects the first curved tube support 18, the third curved tube support, and the to 12 to the connecting rod 19. If the applied load becomes large, the connecting rod 19 may buckle and fail to perform a sufficient function.

Therefore, in the second embodiment, the basic configuration is the same as that of the first embodiment of the present invention shown in FIG. 1, but as shown in FIG. 3, a plurality of connecting rods 19 are provided (FIG. 2). In 3, two connecting rods 19a and 19b).

As a result, the load applied to the connecting rods 19a and 19b is reduced, and buckling of the connecting rods 19a and 19b is avoided.

The above embodiments 1 and 2 can be applied to any W-type radiant tube. In particular, a W-shaped radiant tube using a tube having an elliptical cross section that becomes heavy (for example, a first straight tube, a second straight tube, a third straight tube, a fourth straight tube, a first curved tube, a second If it is applied to a W-shaped radiant tube in which the cross-sectional shapes of the curved tube and the third curved tube are all the same elliptical shape), the effect is further exhibited. Further, it may be applied to a W-shaped radiant tube which has a heavy weight by installing a heat transfer promoter in the tube.

In order to verify the effect of the present invention, an analysis was performed by the finite element method.

At that time, as a conventional example, an analysis model based on the prior art shown in FIG. 4 was used, whereas as an example of the present invention, an analysis model based on the first embodiment of the present invention shown in FIG. 1 was used. .. The cross-sectional shape of the pipe was elliptical.

The analysis result is shown in FIG. When the amount of sagging at the connection point between the third curved pipe and the support of the third curved pipe is compared, it is shown that the amount of sagging in the example of the present invention is 60% or less of that of the conventional example.

This confirmed the effectiveness of the present invention.

1 W type radiant tube 2 1st straight pipe 3 2nd straight pipe 4 3rd straight pipe 5 4th straight pipe 6 1st curved pipe 7 2nd curved pipe 8 3rd curved pipe 9 Combustion gas 10 Exhaust gas 11a Furnace wall 11b Furnace Wall 12 Receiving metal fittings 13 3rd curved pipe support 14 Sliding part 17 Load transfer member 18 1st curved pipe support 19 Connecting rod 20a pin 20b pin 21 Rotation center

Claims (3)

The first straight pipe, the first curved pipe, the second straight pipe, the second curved pipe, the third straight pipe, the third curved pipe, and the fourth straight pipe are provided in this order from the upper side to the lower side. It is an in-core support structure for supporting the W-shaped radiant tube in which the straight pipe is located on the burner side and the fourth straight pipe is located on the exhaust gas side.
The first curved pipe support installed on the first curved pipe, the third curved pipe support installed on the third curved pipe, and the metal fittings attached to the furnace wall to support the third curved pipe support. It has a connecting rod for connecting the first curved pipe support and the third curved pipe support.
The rotational moment acting on the third curved pipe support due to the load received from the third curved pipe by the third curved pipe support is applied to the third curved pipe support by the load received from the connecting rod by the third curved pipe support. An in-core support structure for a W-shaped radiant tube, which is characterized in that it is canceled by a rotational moment in the opposite direction in which it acts. The in-core support structure for a W-shaped radiant tube according to claim 1, wherein the W-shaped radiant tube has a plurality of connecting rods. The cross-sectional shapes of the first straight pipe, the second straight pipe, the third straight pipe, the fourth straight pipe, the first curved pipe, the second curved pipe, and the third curved pipe are all the same. The in-core support structure for a W-shaped radiant tube according to claim 1 or 2, characterized in that it has an elliptical shape.

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