JP3981629B2 - Support structure of W type radiant tube - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a support structure for a W-type radiant tube installed inside a furnace body as a heating source for various heating furnaces.
[0002]
[Prior art]
[Patent Document 1]
Japanese Patent Application No. 8-278003
Since the radiant tube has an advantage that the combustion gas does not mix with the atmosphere in the furnace, it is widely used in various heating furnaces including a continuous annealing furnace for steel sheets. Many of them are W-shaped in order to secure a heat radiation area, and are provided with burners at one or both ends.
[0004]
FIG. 3 is a view showing a conventional W-type radiant tube 1. As shown, the W-type radiant tube 1 includes a first straight pipe 2, a first bend 3, a second straight pipe 4, a second bend 5, a third straight pipe 6, a third bend 7, and a fourth straight pipe 8. The base of the first straight pipe 2 and the tip of the fourth straight pipe 8 are fixed to the furnace body 9. In this example, the burner 10 is arranged at the base of the first straight pipe 2, and the first straight pipe 2, the second straight pipe 4, the third straight pipe 6, and the fourth straight pipe 8 are arranged in a vertical plane. Has been.
[0005]
As shown in FIG. 3, conventionally, a support portion 11 is provided between the second straight pipe 4 and the third straight pipe 6, and a support portion 12 is provided between the third straight pipe 6 and the fourth straight pipe 8. At the same time, a support structure in which a support portion 13 for supporting the third bend 7 on the furnace body side is provided at the tip of the third bend 7 is employed. Since the support portions 11 and 12 have a gap at a low temperature, they do not exhibit a support function, and the right end side of the W-type radiant tube 1 is supported only by a pedestal 14 protruding from the right furnace body 9. Yes.
[0006]
In such a conventional support structure, the support portions 11 and 12 have gaps at low temperatures, and the support portions 11 and 12 are brought into close contact with each other only when thermal deformation due to thermal expansion occurs at high temperatures. It is something that is going to be demonstrated. Accordingly, it should be possible to avoid a large thermal stress that occurs when the support portions 11 and 12 are always brought into close contact with each other both at low and high temperatures.
[0007]
However, since the right end side of the W-shaped radiant tube 1 is supported only by the cradle 14, the supporting portions 11, It is inevitable that the twelve gaps gradually decrease. As a result, the entire deformation of the W-type radiant tube 1 is constrained by these support portions 11 and 12, and the thermal stress is transmitted upward as indicated by an arrow at a high temperature as shown in FIG. There has been a problem in that strong thermal stress is generated in the tube 2 to cause thermal damage such as bending and cracking.
[0008]
Therefore, as shown in Patent Document 1 and FIG. 5, a support portion 15 is also provided at the tip of the first bend 3 to support the weight of the first straight pipe 2 and the second straight pipe 4, and the support portion 12 is closely attached. JP-A-8-278003 proposes a support structure that avoids this problem. However, in the W-type radiant tube 1 in which the burner 10 is provided on the first straight pipe 2, the first straight pipe 2 and the first bend 3 are much hotter than the other parts. Since the support structure of FIG. 5 is provided with the support portion 15 on the high-temperature first bend 3, there still remains a problem that a strong thermal stress is generated in the first straight pipe 2.
[0009]
[Problems to be solved by the invention]
The present invention solves the above-mentioned conventional problems, relaxes the thermal stress acting on the W-type radiant tube, and prevents the damage, thereby supporting a long-life structure of the W-type radiant tube. It was made to provide.
[0010]
[Means for Solving the Problems]
The present invention made to solve the above problems is a structure in which a vertically installed W-type radiant tube in which a burner is provided only on an upper first straight pipe is supported by a furnace body, At the tip of the first bend between the second straight pipe and the second straight pipe and the third straight pipe, the first bend is supported on the furnace body side at a low temperature and the support function is lost at a high temperature. At the position near the first bend between the pipe and the pipe, there is no support function at low temperatures, but at the high temperature, a high temperature support section is provided that lifts the second straight pipe and lifts the first bend from the low temperature support section. It is a feature. In addition, it is preferable to make it the structure which provided the support part which supports these parts to the furnace body side also at the front-end | tip of a 2nd bend and a 3rd bend.
[0011]
According to the support structure for the W-shaped radiant tube of the present invention, the first bend is supported on the furnace body side at the low temperature at the tip of the first bend between the first straight pipe and the second straight pipe, and at the high temperature. Since the low temperature support part which loses a support function is provided, the weights of the first straight pipe and the second straight pipe are supported by the low temperature support part. For this reason, even if time passes, the gap of the high temperature support part provided between the 2nd straight pipe and the 3rd straight pipe does not decrease, and sufficient gap is maintained at low temperature. Therefore, the first straight pipe and the second straight pipe are not restrained from thermal expansion during the temperature rise, and a large thermal stress generated during the temperature rise can be avoided. In addition, since the low temperature support portion that supports the first bend on the furnace body side at a low temperature loses the support function at a high temperature, the first bend can be freely deformed and strong thermal stress is not generated in the first straight pipe 2.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Preferred embodiments of the present invention are shown below.
FIG. 1 is a view showing a preferred embodiment of the present invention, and a W-shaped radiant tube 1 includes a first straight pipe 2, a first bend 3, a second straight pipe 4, a second bend 5, and a third as in the prior art. A straight pipe 6, a third bend 7, and a fourth straight pipe 8 are connected in series, and the base of the first straight pipe 2 and the tip of the fourth straight pipe 8 are fixed to the furnace body 9. A burner 10 is disposed at the base of the first straight pipe 2, and the first straight pipe 2, the second straight pipe 4, the third straight pipe 6, and the fourth straight pipe 8 are arranged in a vertical plane and installed vertically. It is an expression.
[0013]
In the present invention, a low temperature support portion 20 that supports the first bend 3 on the furnace body side at a low temperature is provided at the tip of the first bend 3 between the first straight tube 2 and the second straight tube 4. . The low temperature support portion 20 includes a protrusion 21 extending from the first bend 3 side and a pedestal 22 fixed to the furnace body side. The protrusion 21 is in close contact with the upper surface of the pedestal 22 at a low temperature. The weight of the straight pipe 2, the first bend 3, and the second straight pipe 4 is supported.
[0014]
In the present invention, the high temperature support portion 23 is provided at a position near the first bend 3 between the second straight pipe 4 and the third straight pipe 6. As shown in FIG. 1, the high temperature support portion 23 is formed with a gap between the second straight pipe 4 and has no support function at low temperatures. However, when the temperature is high, the gap closely contacts with the thermal expansion of the W-type radiant tube 1, and the second straight pipe 4 is lifted as shown in FIG. 2 to lift the first bend 3 from the receiving base 22 of the low-temperature support portion 20 described above. It is like that.
[0015]
Note that support portions 24 and 25 for supporting these portions on the furnace body side are also provided at the tips of the second bend 5 and the third bend 7, respectively. These support portions 24 and 25 are in close contact at least at a low temperature, and can support the weight of the second straight pipe 4, the third straight pipe 6, and the fourth straight pipe 8.
[0016]
According to the support structure of the present invention configured as described above, the total weight at the time of low temperature is the low temperature support portion 20 of the first bend 3, the support portion 24 of the second bend 5, and the support portion 25 of the third bend 7. Are supported stably by each. For this reason, the clearance gap of the high temperature support part 23 provided in the lower part of the 2nd straight pipe 4 does not reduce with progress of time.
[0017]
Accordingly, the high temperature support portion 23 keeps a gap at low temperatures and supports the second straight pipe 4 and the first bend 3 for the first time during the temperature rise, so that the heat of the first straight pipe 2 and the second straight pipe 4 is maintained. The expansion is not constrained, and a large thermal stress generated at the time of temperature rise can be avoided. Note that the high temperature support portion 23 loses a gap and adheres at a high temperature, but unlike the conventional case, the high temperature support portion 23 is provided between the second straight pipe 4 and the third straight pipe 6 which are lower in temperature than the first bend 3. 1 No strong thermal stress is generated in the straight pipe 2.
[0018]
Moreover, since the low temperature support portion 20 that supports the first bend 3 on the furnace body side at a low temperature is lifted by the high temperature support portion 23 during the temperature increase and loses the support function, the first bend 3 can be freely deformed at a high temperature. . For this reason, strong thermal stress is not generated in the first straight pipe 2.
[0019]
【The invention's effect】
As described above, the support structure for the W-type radiant tube of the present invention is a device in which the arrangement of the low temperature support portion and the high temperature support portion is devised. Thereby, the thermal stress acting on the W-type radiant tube can be relieved and the damage can be prevented, and there is an effect that the life of the W-type radiant tube can be extended as compared with the conventional case.
[Brief description of the drawings]
FIG. 1 is a front view of a low temperature state showing a preferred embodiment of the present invention.
FIG. 2 is a front view of a high temperature state showing a preferred embodiment of the present invention.
FIG. 3 is a front view of a conventional example in a low temperature state.
FIG. 4 is a front view of a conventional example in a high temperature state.
FIG. 5 is a front view in a low temperature state showing another conventional example.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 W type radiant tube 2 1st straight pipe 3 1st bend 4 2nd straight pipe 5 2nd bend 6 3rd straight pipe 7 3rd bend 8 4th straight pipe 9 Furnace 10 Burner 11 Support part 12 Support part 13 Support Part 14 cradle 15 support part 20 low temperature support part 21 protrusion 22 cradle 23 high temperature support part 24 support part 25 support part

Claims (2)

A vertically installed W-shaped radiant tube having a burner provided only on the upper first straight pipe is supported by the furnace body, and the tip of the first bend between the first straight pipe and the second straight pipe In addition, the first bend is supported on the furnace side at a low temperature, and a low temperature support portion that loses the support function at a high temperature is provided, and at a position near the first bend between the second straight pipe and the third straight pipe, A support structure for a W-type radiant tube, which has a high-temperature support portion that does not have a support function at a low temperature but raises the second straight pipe to raise the first bend from the low-temperature support portion at a high temperature.   The support structure for a W-shaped radiant tube according to claim 1, wherein support portions for supporting these portions on the furnace body side are also provided at the tips of the second bend and the third bend.

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