JPH0249440Y2 - - Google Patents

Description

[Detailed description of the invention] "Field of industrial application" The present invention relates to a double pipe for transporting high-temperature fluids, and in particular to a double pipe suitable for handling high-temperature fluids such as liquid sodium in fast breeder reactor plants. .

``Prior art'' In general, pipes that handle fluids such as liquid sodium in fast breeder reactor plants have a double structure, in which the fluid is transported by an inner pipe, and there is no nitrogen or other impurity between the inner and outer pipes. By sealing in active gas, in the event that fluid leaks from the inner pipe, it is prevented from directly leaking to the outside, and the leakage is easily detected to maintain the integrity of the facility.

Figure 4 shows an example of a double pipe in a liquid sodium transport pipe in a conventional fast breeder reactor plant.
A ring-shaped spacer 1 is provided between the inner tube 1 and the outer tube 2.
1 are provided, and the outside of the outer tube 2 is coated with a heat insulating material 7.

``Problems to be solved by the invention'' However, in the case of liquid sodium in a fast breeder reactor, although the liquid sodium is at a high temperature of, for example, 525°C, the inner tube 1 undergoes significant thermal expansion and contraction.
If a misalignment occurs between the inner tube 1 and the outer tube 2, and in particular, the inner tube 1 tends to be in a so-called hoop state due to the spacer 11 during thermal expansion, etc. There is a problem that thermal stress is concentrated.

The present invention effectively solves the above problems.
The purpose of this invention is to absorb the difference in thermal expansion and contraction between the inner tube and the outer tube, suppress the occurrence of a tightening phenomenon due to the inner tube, and reduce the occurrence of thermal stress at the joint between the inner tube and the spacer.

"Means for solving the problem" The double pipe for high temperature fluid transport of the present invention has a spacer that is easily elastically deformable between the inner pipe for high temperature fluid transport and the outer pipe that covers the inner pipe to connect them. The outer tube is provided in an inclined state with respect to the radial direction, and the outer tube is divided before and after the spacer attachment position, and a connecting bellows is provided at the divided portion, and a tube is provided at the spacer attachment position in the outer tube. It is characterized by the fact that it is equipped with a support snare.

"Function" The double pipe for high temperature fluid transport of the present invention absorbs thermal expansion and contraction in the radial direction of the inner tube by deformation of the inclined spacer, and also absorbs thermal expansion and contraction in the longitudinal direction of the inner tube by the bellows. In this case, by attaching a tube support snubber to the spacer installation position of the outer tube, when the inner tube undergoes thermal expansion and contraction in the radial direction, it supports the outer tube from the outside and supports the spacer as the inner tube undergoes thermal expansion and contraction. can be effectively elastically deformed. In addition, since the outer tube is divided before and after the spacer installation position and connected by bellows, when thermal expansion and contraction occurs in the length direction of the inner tube, the transmission of the thermal expansion and contraction to the outer tube is prevented by the area near the spacer. It is blocked by the bellows part to reduce the influence on the outer tube.

"Example" Hereinafter, an example of a liquid sodium transport pipe for a fast breeder reactor to which the present invention is applied will be described with reference to FIGS. 1 and 2.

This embodiment is also similar to the conventional example shown in FIG. 4 in that it has a double-tube structure consisting of an inner tube 1 and an outer tube 2, but a special structure is constructed between the inner and outer tubes 1 and 2. They differ in that a spacer 3 is provided, and that the outer tube 2 has a split structure before and after the spacer 3 is attached, and a bellows 4 is provided in the split portion. be. That is,
The spacer 3 is provided to be inclined in the shape of a thermal skirt with respect to the radial direction, and the bellows 4 is arranged in a ring shape so as to constitute a part of the wall of the outer tube 2.

Further, at both ends of the spacer 3, both tubes 1 and 2 are provided.
Attachment tubes 5A and 5B of the same diameter are each integrally formed and fixed to both tubes 1 and 2 by welding or the like so as to form a part of the tube wall, and the outer attachment tube 5A has a tube support tube. A snare bar 6 is provided. In the figure, reference numeral 7 is a heat insulating material, reference numeral 8 is a liquid leakage detection tube, and reference numeral 9 is a preheater.

With this structure, when the inner tube 1 becomes high temperature and a temperature difference occurs between the inner tube 1 and the outer tube 2, the inner tube 2 is supported by the snubber 6 from the outside. By expanding the tube 1 and narrowing the opposing distance between the inner and outer tubes 1 and 2, the inclined spacer 3 is deformed, and the connecting portion X between the spacer 3 and the inner tube 1 becomes the second Since the inner tube 1 is moved in the direction shown by the arrow in the figure, the diameter of the inner tube 1 can be expanded as shown by the chain line, and the occurrence of a hoop tightening state due to the spacer 3 is suppressed. Further, when the inner tube 1 is thermally expanded and contracted in the length direction, the outer tube 2 having a split structure can move together with the inner tube 1, and the movement can be absorbed by the bellows 4. Therefore, it is possible to efficiently absorb the difference in thermal expansion and contraction between the inner and outer tubes 1 and 2, and to reduce the occurrence of thermal stress at the connecting portion X between the inner tube 1 and the spacer 3.
Furthermore, since the snubber 6 is provided on the attachment tube 5A of the spacer 3, the snubber 6 can integrally support the inner tube 1 via the spacer 3.

On the other hand, FIG. 3 shows another embodiment of the present invention, in which a restraining device 10 having a gap G facing in the radial direction is disposed between the inner tube 1 and the outer tube 2. G
The diameter of the inner tube 1 is allowed to expand within the range of 1, and the vibration of the inner tube 1 is suppressed against external forces such as earthquakes.

"Effects of the Invention" As explained above, the double pipe for transporting high temperature fluid according to the present invention can provide the following effects.

(i) By providing the spacer in an inclined state, when thermal expansion and contraction occurs in the radial direction of the inner tube due to temperature changes in the inner tube, the spacer can be formed to absorb the thermal expansion and contraction, and the inner tube can absorb the thermal expansion and contraction. It is possible to suppress the occurrence of the pipe hoop tightening phenomenon.

(ii) The difference in thermal expansion and contraction in the length direction between the inner tube and the outer tube can be absorbed by the bellows provided on the outer tube with a split structure.

(iii) Since the snubber is provided at the spacer attachment position in the outer tube, it is possible to restrict the outer tube from following thermal expansion and contraction in the radial direction of the inner tube, and effectively elastically deform the spacer.

(iv) Since the outer tube is divided before and after the spacer installation position and provided with a bellows, the transmission of thermal expansion and contraction in the length direction of the inner tube to the outer tube is effectively blocked near the spacer, and the outer tube is The effects of thermal expansion and contraction of the inner tube can be reduced.

(v) By absorbing the combined thermal displacement of these inner pipes and outer pipes, it is possible to reduce the thermal stress of the parts connected to the inner pipes, and improve the health of the facility.

[Brief explanation of the drawing]

Fig. 1 is a longitudinal cross-sectional view showing an example of a liquid sodium transport pipe for a fast breeder reactor to which the double pipe of the present invention is applied, Fig. 2 is an enlarged view of the part indicated by the chain line in Fig. 1, and Fig. 3 The figure is a partially omitted vertical cross-sectional view showing another embodiment of the present invention, and FIG. 4 is a vertical cross-sectional view showing a conventional example of a double pipe in a liquid sodium transport pipe of a fast breeder reactor. 1...Inner tube, 2...Outer tube, 3...Spacer, 4
...Bellows, 6...Snatsuba, 7...Heat insulation material,
10...Restraint, X...Connection part.

Claims (1)

[Scope of utility model registration request] A spacer that connects the inner tube for high-temperature fluid transport and an outer tube that covers the inner tube, and which is easily elastically deformable, is provided in an inclined state in the radial direction. It is divided into front and rear parts, and a connecting bellows is provided in the divided part.
A double pipe for transporting high-temperature fluid, characterized in that a pipe supporting snubber is attached to the outer pipe at a position where the spacer is attached.