JPH0823476B2 - Heat exchanger - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application] The present invention relates to a shell-and-tube heat exchanger used in, for example, a steam generator of a fast breeder reactor power plant.

(Prior Art) A steam generator used in a fast breeder reactor power plant is
Generally, the structure is as shown in FIG. That is, reference numeral 41 in the drawing denotes a vertical shell container with a bellows 42 interposed in the middle portion thereof, and a water inlet plenum 43 and a steam outlet plenum 44 are provided in the upper and lower portions of this shell container 41. These water inlet plenum 43 and steam outlet plenum 44
A large number of heat transfer tubes 45 ... Are opened through the upper tube plate 46 and the lower tube plate 47, and the water inlet plenum is connected to the water inlet 48.
The water flowing into 43 flows through the heat transfer tubes 45, flows out to the steam outlet plenum 44, and is sent from the steam outlet 49 to a power generation turbine through a steam pipe (not shown). A secondary coolant inlet 50 is provided in the lower body of the shell container 41, and the high-temperature secondary coolant (liquid) flowing from the secondary coolant inlet 50 into the secondary coolant inlet plenum 51. Sodium) flows out to the secondary coolant outlet plenum 52 through the outside of the heat transfer tubes 45, and the secondary coolant return pipe (not shown) is output from the secondary coolant outlet 53 provided in the upper body of the shell container 41. It is designed to return to the intermediate heat exchanger through.

Further, in such a steam generator, when cracks or the like occur in the heat transfer tubes 45, water (or steam) flowing inside the heat transfer tubes 45 comes into contact with a secondary coolant flowing outside the heat transfer tubes 45. However, in order to cause a water-sodium reaction, the heat transfer tube 45 has a double tube structure composed of an inner tube 54 and an outer tube 55 as shown in FIG. 5, and water (or steam) flowing inside the heat transfer tube 45. The secondary cooling material flowing outside the heat transfer tube 45 does not come into contact with the secondary cooling material. In the unlikely event that the inner tube 54 or outer tube of the heat transfer tube 45
Even if cracks etc. occur in 55, the intermediate tube sheet 56 should be placed between the upper tube sheet 46 and the lower tube sheet 47 in order to detect them early.
Is provided, and the occurrence of cracks can be detected through the intermediate plenum 58 formed between the intermediate tube sheet 56 and the lower tube sheet 57.

That is, when a crack occurs in the inner tube 54 of the heat transfer tube 45, water (or steam) flowing in the inner tube 54 leaks from the location of the crack and passes through between the inner tube 54 and the outer tube 55 to form an intermediate portion. Since it leaks to the plenum 58, this is detected by the leak detection nozzle 59.
A leak detection mechanism (not shown) connected to is used for detection. Further, when a crack occurs in the outer pipe 55 of the heat transfer pipe 5, an inert gas such as He sealed in the intermediate plenum 58 leaks to the outside of the outer pipe 55, and the pressure in the intermediate plenum 58 decreases. This is detected by a pressure detection mechanism (not shown) connected to the leak detection nozzle 59.

By the way, in such a steam generator, the inner tube of the heat transfer tube 45 is
Since there is a gap 60 between the outer tube 55 and the outer tube 55, the heat transfer tube 45
There is a problem that the heat transfer performance of is impaired. Therefore, in order to solve such a problem, as shown in FIG. 6, a porous metal 61 such as a sintered metal is interposed between the inner pipe 54 and the outer pipe 55 to improve the heat transfer performance of the heat transfer pipe 45. A steam generator that prevents the decrease is proposed. However, in such a steam generator, since the porosity of the porous metal 61 is not uniform in the axial direction and the circumferential direction of the heat transfer tube 45, the fluid leakage cannot be promptly detected depending on the crack occurrence location.

(Problems to be Solved by the Invention) When the porous metal 61 such as a sintered metal is interposed between the inner tube 54 and the outer tube 55 of the heat transfer tube 45 in this way, the heat transfer performance of the heat transfer tube 45 is improved. Although the decrease can be prevented, there has been a problem that the fluid leakage cannot be detected quickly.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a heat exchanger that can quickly detect fluid leakage without impairing the heat transfer performance of the heat transfer tube.

[Structure of the Invention] (Means for Solving the Problems) In order to solve the above problems, the present invention relates to a shell container having both ends closed with tube sheets and having an entrance window and an exit window in the outer periphery, and this shell container. A plurality of heat transfer tubes disposed inside and a coolant inlet plenum for circulating a high temperature coolant to the outside of the heat transfer tubes, which is formed on the outer peripheral portion of the shell container so as to cover the inlet window and the outlet window. And a coolant outlet plenum, a water inlet plenum and a steam outlet plenum formed outside the tube sheet for circulating a fluid to be heated in the heat transfer tube, and the pipe provided to face each other in the shell container. In a heat exchanger having an intermediate tube plate that forms an intermediate plenum for detecting breakage of the heat transfer tube with a plate, the heat transfer tube has an inner tube whose both ends are fixedly supported by the tube plate. , On the outside of this inner tube And an outer tube whose both ends are fixedly supported by the intermediate tube sheet, and a plurality of outer tubes provided between the outer tube and the inner tube so as to be in close contact with the inner surface of the outer tube and the outer surface of the inner tube. It is characterized by comprising a metal braid body obtained by alternately braiding a band-shaped body obtained by bundling metal element wires in a band shape.

(Operation) In the present invention, by providing a metal braid composed of a large number of metal wires between the inner tube and the outer tube of the heat transfer tube, a fluid passage is formed between the inner tube and the outer tube. Since it is formed uniformly in the axial direction and the circumferential direction, it is possible to quickly detect fluid leakage without impairing the heat transfer performance of the heat transfer tube.

(Example) Hereinafter, the Example of this invention is described with reference to drawings.

FIG. 1 is a sectional view showing an embodiment in which the heat exchanger according to the present invention is applied to a steam generator of a fast breeder reactor power plant. In the figure, reference numeral 1 in the figure is a vertical shell container having a bellows 2 interposed in the middle portion thereof, and a large number of heat transfer tubes 3 are housed inside the shell container 1. These heat transfer tubes 3
2 is composed of an inner pipe 4 and an outer pipe 5 as shown in FIG. 2, and the inner pipe 4 penetrates the upper pipe plate 6 and the lower pipe plate 7 to form water formed in the upper and lower parts of the shell container 1. It is open to the inlet plenum 8 and the steam outlet plenum 9.

The water inlet plenum 8 and the steam outlet plenum 9 are respectively provided with a water inlet 10 and a steam outlet 11, and the water flowing from the water inlet 10 into the water inlet plenum 8 flows inside the heat transfer tube 3, that is, inside the inner tube 4. It flows out to the steam outlet plenum 9 and is sent from the steam outlet 11 to a power generation turbine through a steam pipe (not shown).

A secondary coolant inlet 12 is provided in the lower body of the shell container 1, and the high-temperature secondary coolant flowing from the secondary coolant inlet 12 into the secondary coolant inlet plenum 13 ( Liquid sodium) flows out to the secondary coolant outlet plenum 14 through the outside of the heat transfer pipe 3, that is, the outside of the outer pipe 5, and is illustrated from the secondary coolant outlet port 15 provided in the upper body portion of the shell container 1. Not Return to the intermediate heat exchanger through the secondary coolant return pipe.

On the other hand, intermediate tube plates 16 and 17 are provided between the upper tube sheet 6 and the lower tube sheet 7, and between these intermediate tube sheets 16 and 17 and the upper tube sheet 6 and the lower tube sheet 7. , Each intermediate plenum 1
8 and 19 are formed. An inert gas such as He is enclosed in these intermediate plenums 18 and 19 and communicates with each other via the outer pipe 5 of the heat transfer pipe 3. Also, the intermediate plenum 18,19
Leak detecting nozzles 20 and 21 are provided in the leak detecting nozzles 20 and 21, and a leak detecting mechanism and a pressure detecting mechanism (not shown) are connected to the leak detecting nozzles 20 and 21, respectively.

Between the inner tube 4 and the outer tube 5 of the heat transfer tube 3, a metal braided body 22 made up of a large number of metal element wires is provided as shown in FIG. This metal braid 22 is, for example, as shown in FIG. 3, a pair of band-shaped bodies 23a and 23b obtained by bundling a plurality of metal element wires such as copper in a band shape and alternately braided in a net shape. It is in close contact with the outer peripheral surface and the inner peripheral surface of the outer tube 5.

In the above configuration, for example, the inner tube 4 of the heat transfer tube 3
When a crack occurs in the inner pipe 4, water (or steam) flowing through the inner pipe 4 leaks from the crack occurrence point and flows between the inner pipe 4 and the outer pipe 5 into the intermediate plenums 18, 19,
The occurrence of cracks can be detected by detecting this with a leak detection mechanism connected to the leak detection nozzles 20 and 21.

When a crack occurs in the outer tube 5 of the heat transfer tube 3, an inert gas such as He enclosed in the intermediate plenums 18 and 19 leaks to the outside of the outer tube 5 from the location of the crack, and the intermediate plenum Since the pressure inside 18, 19 drops, the occurrence of cracks can be detected by detecting this with a pressure detection mechanism connected to the leak detection nozzles 20, 21.

Thus, by providing the metal braided body 22 made of a large number of metal wires between the inner tube 4 and the outer tube 5 of the heat transfer tube 3,
Since fluid passages are uniformly formed in the axial direction and the circumferential direction of the heat transfer tube 3 between the inner tube 4 and the outer tube 5, fluid leakage can be quickly detected without impairing the heat transfer performance of the heat transfer tube 3. can do. The metal braid 22 has a larger diameter when contracted in the axial direction and a smaller diameter when expanded in the axial direction. Therefore, the metal braid 22 can be easily inserted into the outer periphery of the inner pipe 4 and evenly adhered to the outer periphery of the inner pipe 4. be able to.

Further, in the above-described embodiment, the metal braid 22 has a configuration in which the band-shaped bodies 23a and 23b obtained by bundling a plurality of metal wires in a band shape are alternately braided in a net shape, so that the metal braid 22 is attached. After inserting the inner tube 4 into the outer tube 5, the outer tube 5 is compressed by a die or the like to form a gap for circulating a leak fluid inside the metal braid 22 when the heat transfer tube 3 is manufactured. In addition, it is possible to prevent deterioration of heat transfer performance due to breakage of the wire.

The present invention is not limited to the above embodiment. For example, the metal braid 22 may be made of different kinds of metal wires (for example, copper and stainless steel). In this way, by configuring the metal braid 22 with different types of metal strands,
The strength of the metal braid 22 can be increased. Further, by plating the surface of the metal braid 22, the heat transfer performance of the metal braid 22 is improved, so that the heat of the secondary coolant can be efficiently transferred to the water flowing in the heat transfer tube 3. . The metal braid 22 is not limited to the one shown in FIG. 3, and may be, for example, a large number of metal element wires braided in a net shape. In addition, in the above-described embodiment, the mechanical strength of the heat transfer tube 3 when expanding the inner tube 4 can be secured. The reason is that, when the inner tube 4 of the heat transfer tube 3 is attached to the intermediate tube plates 16 and 17, the inner tube 4 is generally expanded from the inside in order to improve the adhesion between the inner tube 4 and the intermediate tube plates 16 and 17. Tube expansion processing is performed. At this time, when the porous metal layer formed between the inner tube 4 and the outer tube 5 is formed of a tubular body made of, for example, a sintered metal, the sintered metal is expanded when the inner tube 4 is expanded as described above. The tubular body consisting of may be damaged. However, in this embodiment, by providing the metal braid 22 made of a large number of metal wires between the inner tube 4 and the outer tube 3, it is possible to secure the mechanical strength of the heat transfer tube 3 when expanding the tube.

Further, although the steam generator of the fast breeder reactor power plant has been described in the above embodiment, the present invention can be applied to a general heat exchanger.

[Effects of the Invention] As described above, according to the present invention, it is possible to quickly detect fluid leakage without impairing the heat transfer performance of the heat transfer tube, and improve the reliability of the heat exchanger. it can. Also, after inserting the inner tube with the metal braid attached to the outer tube,
When manufacturing the heat transfer tube by compressing the outer tube with a die or the like, it is possible to reliably form a gap for circulating the leaked fluid inside the metal braid, and to reduce heat transfer performance due to wire breakage. Can be prevented.

[Brief description of drawings]

1 to 3 are views showing an embodiment of the present invention, FIG. 1 is a sectional view of a steam generator, FIG. 2 is a sectional view of a heat transfer tube,
FIG. 3 is a diagram showing an example of a metal braid. Also, the fourth
4 to 6 are views for explaining the prior art, and FIG.
FIG. 5 is a sectional view of a steam generator, FIG. 5 is a sectional view of a heat transfer tube, and FIG. 6 is a view showing a conventional example in which a porous metal is interposed between an inner tube and an outer tube of the heat transfer tube. 1 ... Shell container, 3 ... Heat transfer tube, 4 ... Inner tube, 5 ...
Outer pipe, 10 ... Water inlet, 11 ... Steam outlet, 12 ... Secondary coolant inlet, 15 ... Secondary coolant outlet, 18, 19 ... Intermediate plenum, 20, 21 ... Leak Detection nozzle, 22 ... Metal braid.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Iwao Oshima, Iwao Oshima, 1-1-7 Uchisaiwaicho, Chiyoda-ku, Tokyo Inside Nihon Nuclear Power Co., Ltd. (56) Reference JP-A-63-311091 (JP, A)

Claims (1)

[Claims] 1. A shell container having both ends closed by tube plates and having an inlet window and an outlet window on the outer periphery, a plurality of heat transfer tubes arranged in the shell container, and the inlet on the outer periphery of the shell container. A coolant inlet plenum and a coolant outlet plenum for covering a window and an outlet window for circulating a high-temperature coolant to the outside of the heat transfer tube, and a cover formed inside the heat transfer tube inside the tube sheet. An intermediate plenum for detecting breakage of the heat transfer tube is provided between the water inlet plenum and the steam outlet plenum for circulating the heating fluid and the tube plate provided to face each other in the shell container. In a heat exchanger having a tube plate, the heat transfer tube has an inner tube whose both ends are fixedly supported by the tube plate, and both ends provided outside the inner tube are fixedly supported by the intermediate tube plate. Outer tube,
A metal, which is provided between the outer tube and the inner tube so as to be in close contact with the inner surface of the outer tube and the outer surface of the inner tube, and which is formed by alternately braiding a band-shaped body obtained by bundling a plurality of metal element wires in a band shape in a mesh shape. A heat exchanger comprising a braid.