JPH01256791A - Heat exchanger - Google Patents

Abstract

PURPOSE:To quickly detect the leakage of fluid without imparing the heat transmission performance of a heat transmission pipe by disposing a metallic mesh consisting of a number of metallic wires between the inner and outer pipes of a heat transmission pipe. CONSTITUTION:Between the inner pipe 4 and outer pipe 5 of a heat transmission pie 3, a metallic mesh 22 is disposed which comprises wire belts 23a, 23b composed of a number of wires of copper, etc., and is tightly in contact with the outer surface of the inner pipe 4 and the inner surface of the outer pipe 5. When a crack should occur in the inner pipe 4 of the heat transmission pipe 3, the flowing water or steam leaks out of the crack between the inner pipe 4 and the outer pipe 5 into intermediate plenums 18, 19, and a leakage sensing mechanism connected to leak sensing nozzles 20, 21 detects the leakage and the crack. When a crack should occur in the outer pipe 5, the inner gas contained in the intermediate plenums 18, 19 leaks from the crack outside the outer pipe 5, causing a drop in the pressure in the intermediate plenums 18, 19, which is picked up by a pressure sensing mechanism connected to the leak sensing nozzles 20, 21 to detect generating of a crack.

Description

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

(Prior Art) A steam generator used in a fast breeder reactor power plant generally has a configuration as shown in FIG. That is,
In the figure, reference numeral 41 denotes a vertical shell container with a bellows 42 interposed in the middle, and a water inlet blennium 43 and a steam outlet blemish 44 are provided at the upper and lower parts of the shell container 41.

These water inlet blennium 43 and steam outlet blennium 44
, a large number of heat exchanger tubes 45 are opened through the upper tube sheet 46 and the lower tube sheet 47, and the water flowing into the water inlet blennium 43 from the water inlet 48 flows into the heat exchanger tubes 45. flows through the steam outlet Blenheim 44, and flows out to the steam outlet Blenheim 44.
From 9, the steam is sent to the power generation turbine through a steam pipe (not shown). Further, a secondary coolant inlet 50 is provided in the lower body of the shell container 41, and high-temperature secondary coolant (liquid Sodium) is heat exchanger tube 45.
... flows out to the secondary coolant outlet blemish 52 through the outside of the shell container 41, and passes through the secondary coolant return pipe (not shown) from the secondary coolant outlet 53 provided in the upper body of the shell container 41 to the intermediate heat. It will now return to the exchanger.

In addition, in such a steam generator, if a crack or the like occurs in the heat exchanger tubes 45, the water (or steam) flowing inside the heat exchanger tubes 45 and the secondary coolant flowing outside the heat exchanger tubes 45 will contact and cause a water-sodium reaction.
As shown in the figure, the heat exchanger tube 45 has a double tube structure consisting of an inner tube 54 and an outer tube 55, and the water flowing inside the heat exchanger tube 45 (
or steam) and the secondary coolant flowing outside the heat exchanger tubes 45 do not come into contact with each other. Also, in the unlikely event that heat transfer tube 4
In order to detect cracks early even if they occur in the inner tube 54 or outer tube 55 of 5, an intermediate tube sheet 56 is provided between the upper tube sheet 46 and the lower tube sheet 47. 56 and the lower tube plate 57
8, it is possible to detect the occurrence of cracks.

That is, when a crack occurs in the inner tube 54 of the heat transfer tube 45, water (
or steam) leaks and flows into the intermediate blemish 58 through the space between the inner pipe 54 and the outer pipe 55, so that this is detected by a leak detection mechanism (not shown) connected to the leak detection nozzle 59. It has become. Furthermore, if a crack occurs in the outer tube 55 of the heat transfer tube 5, the inert gas such as He sealed in the intermediate blemish 58 leaks to the outside of the outer tube 55, and the pressure inside the intermediate blemish 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, since the gap portion 60 exists between the inner tube 54 and the outer tube 55 of the heat exchanger tube 45, there is a problem that the heat transfer performance of the heat exchanger tube 45 is impaired. Therefore, in order to solve this problem, as shown in FIG. 6, a porous metal 61 such as sintered metal is interposed between the inner tube 54 and the outer tube 55 to improve the heat transfer performance of the heat transfer tube 45. A steam generator that prevents deterioration has been 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, fluid leakage cannot be quickly detected depending on the location where cracks occur.

(Problem to be Solved by the Invention) When the porous metal 61 such as sintered metal is interposed between the inner tube 54 and the outer tube 55 of the heat exchanger tube 45 in this way, the heat exchanger tube 45
Although it is possible to prevent the deterioration of the heat transfer performance of No. 5, there is a problem that fluid leakage cannot be detected quickly.

The present invention was made in view of these problems, and
The present invention aims to provide a heat exchanger that can quickly detect fluid leakage without impairing the heat transfer performance of heat exchanger tubes.

[Configuration of the Invention (Means for Solving the Problems) In order to solve the above problems, the present invention aims to prevent leakage of fluid flowing through a heat transfer tube consisting of an inner tube and an outer tube. The heat exchanger is equipped with a leakage detection mechanism that detects leakage through a gap between the heat exchanger tube and the heat exchanger tube, characterized in that a metal braided body made of a large number of metal wires is provided between the inner tube and the outer tube of the heat exchanger tube.

(Function) In the present invention, by providing a metal braided body made of a large number of metal wires between the inner tube and the outer tube of the heat exchanger tube, a fluid passage is formed between the inner tube and the outer tube of the heat exchanger tube. Since they are formed uniformly in the axial and circumferential directions, fluid leakage can be quickly detected without impairing the heat transfer performance of the heat transfer tube.

(Example) Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view showing an embodiment in which a 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 denotes a vertical shell container with a bellows 2 interposed in the middle, and a large number of heat exchanger tubes 3 are housed inside the shell container 1. These heat transfer tubes 3... consist of an inner tube 4 and an outer tube 5 as shown in FIG. and water inlet Blenheim 8 formed at the bottom.
and open to the steam outlet blennium 9.

A water inlet 10 and a steam outlet 11 are provided in the water inlet blennium 8 and steam outlet blennium 9, respectively. The steam flows through the steam outlet blenum 9, and is sent from the steam outlet 11 to the power generation turbine through a steam pipe (not shown).

Further, a secondary coolant inlet 12 is provided in the lower body of the shell container 1, and high temperature secondary coolant (
The liquid sodium) passes through the outside of the heat transfer tube 3, that is, the outside of the outer tube 5, and flows out into the secondary coolant outlet brenum 14, and then flows into the secondary coolant outlet 15 provided in the upper body of the shell container 1.
The coolant returns to the intermediate heat exchanger through a secondary coolant return pipe (not shown).

On the other hand, an intermediate tube sheet 16.17 is provided between the upper tube sheet 6 and the lower tube sheet 7, and between these intermediate tube sheets 16.17 and the upper tube sheet 6 and the lower tube sheet 7, , respectively, are formed with intermediate brenums 18,19. Inert gas such as He is sealed in these intermediate blemishes 18 and 19,
They communicate with each other via the outer tube 5 of the heat transfer tube 3. Also,
Leak detection nozzle 20゜2 is installed in the middle blemish 18.19.
1 are provided, and a leak detection mechanism and a pressure detection mechanism (not shown) are connected to these leak detection nozzles 20 and 21, respectively.

As shown in FIG. 2, a metal braided body 22 made of a large number of metal wires is provided between the inner tube 4 and the outer tube 5 of the heat transfer tube 3. As shown in FIG. The metal braided body 22 is, for example, a pair of band-shaped bodies 23a made by bundling a plurality of metal wires such as copper into a band-like shape, as shown in FIG.

23b are alternately braided in a net shape, and are in close contact with the outer circumferential surface of the inner tube 4 and the inner circumferential surface of the outer tube 5.

In the above configuration, for example, if a crack occurs in the inner tube 4 of the heat transfer tube 3, the water (or steam) flowing inside the inner tube 4 leaks from the crack occurrence point, causing the inner tube 4 and the outer tube 5 to leak.
Since the leakage gas flows out into the intermediate blemish 18.19 through the gap between the leakage detection nozzle 20.21 and the leakage detection mechanism connected to the leakage detection nozzle 20.21, the occurrence of cracks can be detected.

In addition, if a crack occurs in the outer tube 5 of the heat exchanger tube 3,
An inert gas such as He sealed in the intermediate blemish 18, 19 leaks to the outside of the outer tube 5 from the crack occurrence location,
Since the pressure within the intermediate blemish 18.19 decreases, the occurrence of cracks can be detected by detecting this with a pressure sensing mechanism connected to the leak detection nozzle 20.21.

In this way, 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 exchanger tube 3,
Since fluid passages are formed uniformly in the axial and circumferential directions of the heat transfer tubes 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 tubes 3. can do. Furthermore, when the metal braided body 22 is contracted in the axial direction, the diameter increases, and when stretched in the axial direction, the diameter decreases, so the inner tube 4
It can be easily inserted into the outer periphery of the inner tube 4, and it can be made to adhere uniformly to the outer periphery of the inner tube 4.

Note that the present invention is not limited to the above embodiments.

For example, the metal braided body 22 may be composed of different types of metal wires (eg, copper, stainless steel, etc.). By configuring the metal braided body 22 with different types of metal wires in this way,
The strength of the metal braided body 22 can be increased. moreover,
By plating the surface of the metal braided body 22, the heat transfer performance of the metal braided body 22 is improved, so that the heat of the secondary cooling can be efficiently transferred to the water flowing in the heat transfer tube 3. Note that the metal braided body 22 is not limited to that shown in FIG. 3, and may be one in which a large number of metal wires are knitted into a net shape, for example.

Furthermore, although the above embodiments have been described with respect to a steam generator for a fast breeder reactor power plant, the present invention is also applicable to general heat exchangers.

[Effects of the Invention] As explained above, according to the present invention, fluid leakage can be quickly detected without impairing the heat transfer performance of the heat exchanger tubes, and the reliability of the heat exchanger can be improved. can.

[Brief explanation of the drawing]

1 to 3 are wooden diagrams of an embodiment of the present invention, in which FIG. 1 is a sectional view of a steam generator, FIG. 2 is a sectional view of a heat exchanger tube,
FIG. 3 is a diagram showing an example of a metal braided body. Also, the fourth
Figures 6 through 6 are diagrams for explaining the prior art.
5 is a sectional view of a steam generator, FIG. 5 is a sectional view of a heat exchanger tube, and FIG. 6 is a diagram showing a conventional example in which a porous metal is interposed between an inner tube and an outer tube of a heat exchanger tube. 1... Shell container, 3... Heat exchanger tube, 4... Inner tube,
5... Outer pipe, 10... Water inlet, 11... Steam outlet, 12... Secondary coolant inlet, 15... Secondary coolant outlet, 18.19... Intermediate Blenheim, 20.2
1... Leak detection nozzle, 22... Metal braided body. Applicant's Representative Patent Attorney Takehiko Suzue Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6

Claims (1)

[Claims] In a heat exchanger equipped with a leakage detection means for detecting leakage of a fluid flowing through a heat exchanger tube consisting of an inner tube and an outer tube through a gap between the inner tube and the outer tube, the inner tube and the outer tube of the heat exchanger tube are A heat exchanger characterized in that a metal braided body made of a large number of metal wires is provided between the heat exchanger and the metal wire.