JPH01497A - Liquid metal fast breeder reactor heat exchanger - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an improvement in a heat exchanger for a liquid metal fast breeder reactor.

[Conventional technology]

Conventionally, U.S. Pat. No. 4,560,533 (Des.

24,. 1985) has been proposed, which will be explained with reference to FIGS. 6 to 8.

6 is a vertical sectional view of the main part of the nuclear reactor, FIG. 7 is a detailed view of the heat pipe shown in FIG. 6, and FIG. 8 is a sectional view taken along arrow 13-8 in FIG. 7. In the figure, 11 is a heat pipe, 19 is a disc-shaped intermediate heat medium 521 made of mercury, 25 is a reactor vessel, 26 is a core protection inner cylinder, 27 is sodium core coolant, 28 is a reactor core, and 29 is a It's a turbine. Also, 3o
31 is a heat exchanger tube in the heat pipe, 31 is an inlet side heat exchanger tube, 32 is an outlet side heat exchanger tube, 33 is a U-shaped part of the heat exchanger tube, 34 is a water and steam pump, 35 is an inlet side header, and 36 is a ladder to the outlet side. .

First, the core cooling system starts with sodium 27, which is the coolant heated in the core 28 in the reactor vessel 25.
When heated, it rises inside the core protection cylinder 26 and flows in the circumferential direction from the upper end, and is cooled by the heat pipe 11 installed in the reactor vessel 25 and exchanging heat with water vapor.

As a result of this cooling, it descends through a flow path with an annular cross section formed by the reactor vessel 25 and the core protection cylinder 26, returns to the lower part of the reactor core 28, and follows a path where it is heated again in the reactor core 28. Next, the steam system that generates power in the turbine 29 is connected to the reactor vessel by following the piping with the water and steam system pump 34.
5. The heat pipe 11 enters the ladder 35 to the inlet side of the upper part and flows down several inlet side heat transfer tubes 31 from the ladder 35 to the inlet side.
The steam enters the heat pipe 11, becomes steam, and ascends the outlet heat exchanger tube 32. The steam collected from the outlet heat exchanger tube 32 to the outlet header 36 follows the piping and reaches the turbine 29, where the steam rotates the turbine 29 and generates electricity.

The heat exchange action inside the heat pipe 11 is shown in FIGS. 7 and 8.
To explain in detail with the diagram, first, the water driven and sent by the water/steam system pump 34 is sent to the inlet side header 35. It is led into the reheat pipe 11 through the inlet side heat exchanger tube 31. In the heat pipe 11, the intermediate heat medium 19 is heated through the heat pipe 11 whose outer periphery is heated by sodium 27, evaporates, becomes a gas, heats the heat transfer tube 30 in the heat pipe, and heats the water that is the internal fluid. By doing so, the water is vaporized. By heating the heat transfer tube 30 in the heat pipe, the intermediate heat medium 19 is deprived of heat, cooled, and condensed again to return to a liquid state. The heat exchanger tube 30 in the heat pipe is the inlet side heat exchanger tube 3
1, a heat exchanger tube U-shaped portion 33 at the inverted portion at the lower end, and an outlet side heat exchanger tube 32, and an inlet side heat exchanger tube 31. The two heat exchanger tubes of the outlet side heat exchanger tubes 32 are connected at their lower ends in a U-shape.

On the other hand, in a nuclear reactor, the core 28 inside the reactor vessel 25
When the sodium 27 (primary sodium) heated in This should be avoided at all costs. For this reason, in conventional structures even earlier than the conventional structure described above, primary main cooling system equipment and secondary main cooling system equipment were provided.

In order to omit this secondary main cooling system equipment, the conventional structure shown in Figs. The structure was designed to prevent contact between primary sodium, water, and steam even if the boundary wall were damaged.

In the conventional structure shown in Fig. 7, the water and steam side heat exchanger tubes are U-shaped, so when forming a U-shaped bent part by bending the heat exchanger tube, the heat exchanger tube inside the heat vibrator The distance between the descending portion and the ascending portion of heat pipe 30 is regulated, and as a result, the outer diameter of heat pipe 11 becomes large. It is also possible to use joints such as elbows, but in this case, the number of weld lines increases, ensuring the reliability of the heat exchanger tube, and limiting the bending process of the U-shaped part, which is not preferable from the viewpoint of manufacturability. . Furthermore, when a U-shaped pipe is used, there is a heat balance in the downcomer pipe section, so there is a potential for the water supply to boil in the downcomer pipe section, resulting in unstable flow. Furthermore, since each heat pipe 11 is installed independently in the reactor vessel 25, the heat pipe working fluid cannot be drained, making it impossible to extract heat in the event of an accident on the water side. That is, when the heat removal is lost, the heat pipe container is maintained at high temperature and pressure, and the structure for many heat pipes 11 to penetrate through the roof slab, and the heat,
It is difficult to take measures regarding radiation shielding.

Regarding this type of technology, in addition to the above, there are also
No. 3901 has been proposed.

[Problem that the invention seeks to solve]

In the conventional structure described above, a U-shaped tube is used inside the heat pipe, which has problems with manufacturing efficiency and soundness. The problem is that no consideration is given to creating a structure that does not use heat exchanger tubes, and the diameter of the heat pipe is increased and the heat exchanger is made larger, which is undesirable from the standpoint of ensuring the structural soundness and reliability of the heat exchanger tube. It has points.

The present invention has been made in view of the above situation.

The shape can be made smaller and the heat transfer tube has structural integrity.

The purpose of this invention is to provide a heat exchanger for a liquid metal fast breeder reactor that can improve reliability.

[Means for solving problems]

The above purpose is to transfer the heat of the liquid metal in a liquid metal fast breeder reactor to a plurality of heat pipes that are in contact with the outer periphery of the reactor, and to transfer the heat transferred to the heat pipes to the heat pipes via an intermediate heat medium. A bayonet-type heat transfer tube is installed in the heat pipe, in which heat is transferred to and exchanged with water that is guided through the pipe, flows from above, turns around at the lower end of the heat pipe, rises, and is discharged. At the same time, the water flowing down the inner tube of the heat transfer tube of the bayonet type heat transfer tube is turned back at the lower end of the bayonet type heat transfer tube, and the inner circumference of the outer heat transfer tube is concentrically arranged around the outer circumference of the inner tube of the heat transfer tube. and the intermediate heat medium is sealed between the outer periphery of the outer heat transfer tube and the inner periphery of the heat pipe of the bayonet type heat transfer tube. This is achieved by a liquid metal fast breeder reactor heat exchanger.

[Effect]

As described in the description of the embodiments below, the water flowing down inside the heat exchanger tube inner tube 17 of the bayonet type heat exchanger tube 10 is turned back at the lower end of the bayonet type heat exchanger tube 10, and the water flows down into the heat exchanger tube inner tube 17. It rises between the outer circumferential surface and the inner circumferential surface of the outer heat transfer tube 15. Between the time when water flows into the inner tube 17 of the heat exchanger tube and flows out from the outer tube 15 of the heat exchanger tube, water is heated by the intermediate heat medium 19 that is filled between the inner circumferential surface of the heat pipe 11 and the outer circumferential surface of the bayonet type heat transfer tube 10. Heated and heat exchanged. The intermediate heat medium 19 is 1
It is heated by sodium sodium through the heat pipe 11. In the flow path structure in which water is heated in the heat pipe 11, since the bayonet type heat exchanger tube 10 does not have a conventional heat exchanger tube U-shaped part, the heat pipe It becomes possible to effectively utilize the cross-sectional area of the heat pipe 11 without reducing the heat exchange area of the heat exchanger tubes inside the heat pipe 11.
By reducing the cross-sectional area of 1, it is possible to downsize the heat exchanger as a whole. Moreover, as the diameter of the heat pipe 11 is reduced, pressure resistance can be improved, and structural soundness and reliability can be improved. It is particularly suitable as a heat pipe that handles high-temperature liquid metal.

[Example] Hereinafter, the heat exchanger for a liquid metal fast breeder reactor of the present invention will be explained using examples and FIGS. 1 to 4, in which the same parts as in the conventional art are denoted by the same reference numerals. Figure 1 is an overall structural diagram, Figure 2 is a detailed diagram of the heat pipe in Figure 1, Figure 3 is a sectional view taken along the line A-A in Figure 2, and Figure 4 is the heat exchanger in Figure 1. It is an explanatory diagram of connection with a nuclear reactor vessel. In the figure, 1 is a heat exchanger, 2 is a shell, and 3 is a heat exchanger.
4 is a sodium inlet plenum, 4 is a sodium outlet plenum, 5 is a support skirt, 6 is a water supply inlet ice chamber, 7 is a steam outlet ice chamber, 8 is an upper intermediate heat medium plenum, 9 is a lower intermediate heat medium plenum, 10 is a heat transfer tube inner tube This is a bayonet type heat exchanger tube in which an outer heat exchanger tube 15 is disposed concentrically around the outer periphery of the heat exchanger tube 17, and the lower end of the inner heat exchanger tube 17 is open near the lower end of the outer heat exchanger tube 15 whose lower end is closed. 12 is a tube bundle group consisting of a plurality of heat pipes 11, and 13 is an upper heat pipe tube plate.

14 is a lower heat pipe tube sheet, 16 is a steam outlet tube sheet, 1
8 is a steam inlet tube plate. A wick 20 is attached to the inner wall surface of the heat pipe 11 with pleats or wire mesh provided on the inner peripheral surface so that the mercury of the intermediate heat medium 19 easily rises due to surface tension and has good wettability. In the space between the inner peripheral surface of the wick 20 and the outer peripheral surface of the bayonet type heat exchanger tube 10.

A plurality of yanbars 2 are provided with a plurality of disk-shaped plates 21 through which bayonet-type heat exchanger tubes 10 are passed at a predetermined pitch in the vertical direction, and are separated by the disk-shaped plates 21 in the vertical direction.
2 is formed.

In addition, a small hole (not shown) is provided in the disc-shaped value 21 in order to keep the pressure between each chamber 22 constant.
The disk-shaped value 21 serves not only to reinforce the heat pipe 11 itself but also to support the bayonet type heat exchanger tube 10. Furthermore, in order to quickly circulate the condensed intermediate heat medium 19 to the tube wall side (evaporation part) of the heat pipe 11, the disk-shaped machine 21
The fixed part side of the bayonet type heat exchanger tube 10 is located at a higher position than the mounting position of the wick 20 on the outer peripheral part. Then, the intermediate heat medium 19 receives the heat of the primary sodium in the wick 20 portion via the heat pipe 11, evaporates and fills the chamber 22, and is cooled and liquefied in contact with the outer peripheral surface of the bayonet type heat transfer tube 10. That is, after exchanging heat with the water in the bayonet type heat transfer tube 10 and heating it, it flows back to the wick 20 side.

On the other hand, the primary sodium 1-lium as a heating medium is transferred from the pressure vessel 25 side of FIG. 4 to the sodium inlet nozzle 23 of FIG.
The heat flows into the shell 2 and flows down the area formed by the shell 2 and the heat pipe 11. At this time, the heat pipe 11
The heat is transferred to the intermediate heat medium 19 inside, and the temperature becomes low, reaches the lower sodium outlet plenum 4, and flows out from the shell 2. The intermediate heat medium 19 in the heat pipe 11 rises in the wick 20 portion as a liquid phase and evaporates by obtaining heat from the primary sodium flowing outside the wall of the heat pipe 11. This evaporated intermediate heat medium 19 flows down inside the bayonet type heat exchanger tube 10 and then transfers heat to rising water and steam, condenses and becomes a liquid, flows down the outer circumferential wall of the bayonet type heat exchanger tube 10 and is wicked by the disk shape @21. It is returned to 20 and goes around. In addition, the supply water that has flowed into the water supply inlet water chamber 6 descends from the water supply inlet tube plate 18 into the heat transfer tube inner tube 17 of each bayonet type heat transfer tube 10, changes direction at the lower end, and transfers to the heat transfer tube inner tube 17. The annulus portion formed by the heat tube outer tube 15 is raised. At this time, the feed water is heated by the intermediate heat medium 19 outside the bayonet type heat exchanger tube 10, boils and evaporates into steam, which is collected by the steam outlet tube plate 16 and flows out through the steam outlet water chamber 6. That is, in the heat exchanger 1, the heat of the primary sodium is transferred to the steam side as the latent heat of the intermediate heat medium 19.

Moreover, in this embodiment, each heat pipe 11 is.

Since the upper working fluid plenum 8 and the lower working fluid plenum 9 communicate with each other, the pressure of the intermediate heat medium 19 in each heat pipe 11 is constant, that is, the pressure of the intermediate heat medium 19 is constant.
This has the advantage that the temperature remains constant, which is preferable from the viewpoint of heat transfer performance and structural integrity. And heat pipe 1
1, Bayonetsu 1-type heat exchanger tube 10 is installed so that water can be turned in a U-turn without providing a conventional U-shaped structure for the heat exchanger tube.
By using the heat pipe 11, the cross-sectional area of the heat pipe 11 can be used more effectively than in the case of the above-mentioned U-shaped structure without reducing the heat exchange area of the heat exchanger tubes within the heat pipe 11. Therefore, the cross-sectional area of the heat pipe 11 is reduced,
Overall, the heat exchanger 1 can be made smaller.

This allows the diameter of the heat pipe 11 to be reduced.

If the coolant in the core 28 becomes abnormally high in temperature during a nuclear reactor accident, etc., the intermediate heat medium 19 in the heat pipe 11
Although the heat pipe 11 is also subjected to high temperature and high pressure, even in such a case, by reducing the diameter of the heat pipe 11, the pressure resistance performance is improved and the structural soundness can be improved. It goes without saying that a plurality of bayonet-type heat exchanger tubes 10 may be installed in the heat pipe 11.

As described above, by arranging the bayonet type heat transfer tube 10 inside the heat pipe 11 and reducing the diameter of the heat pipe 11, and by eliminating the secondary main cooling equipment, the cooling system equipment is changed as shown in Fig. 4. Configuration is greatly simplified.

Further, as shown in FIG. 5, in order to promote wetting of the wick 20 above the heat pipe 11, the intermediate heat medium 19 (liquid phase) in the lower intermediate heat medium plenum 9 is pumped into the upper intermediate heat medium by a booster pump 24. It may be pumped up to the plenum 8 and supplied to the wick 20 portion of each heat pipe 11.

In this way, the heat exchanger for the liquid metal fast breeder reactor of this example is configured so that a bayonet type heat transfer tube is disposed inside the heat pipe to exchange heat with the intermediate heat medium, so that primary sodium and water/steam can be exchanged. By making the boundary a double wall, the secondary main cooling system equipment can be omitted, simplifying the cooling system equipment, making the heat pipe diameter smaller, making the heat exchanger smaller, and improving the structural soundness of the heat transfer tube.

Can improve reliability.

[Effects of the Invention] As described above, the heat exchanger for a liquid metal fast breeder reactor of the present invention can reduce the size and improve the structural integrity of the heat transfer tubes.
This has the effect of improving reliability.

[Brief explanation of the drawing]

FIG. 1 is an overall structural diagram of an embodiment of the heat exchanger for a liquid metal fast breeder reactor of the present invention, FIG. 2 is a detailed diagram of the heat pipe in FIG. 1, and FIG. 3 is an arrow A-A in FIG. 4 is an explanatory diagram of the connection between the heat exchanger of FIG. 1 and the M7-furnace vessel, FIG. S is an explanatory diagram of another example similar to the overall structural diagram of FIG. 1, Figure 6 is a sectional view of the main part of a nuclear reactor with a conventional heat exchanger;
This figure is a detailed view of the heat pipe in FIG. 6, and FIG. 8 is a sectional view taken along the line B--B in FIG. 7. 1... Heat exchanger, 10... Bayonet type heat exchanger tube. 11... Heat pipe, 15... Heat transfer tube outer tube, 17
...Heat transfer tube inner tube, 19...Intermediate heat medium, 27...
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Claims (1)

[Claims] 1. The heat of the liquid metal in the liquid metal fast breeder reactor is transferred to a plurality of heat pipes whose outer periphery is in contact with the liquid metal, and the heat transferred to the heat pipes is transferred through an intermediate heat medium. In the heat pipe, a bayonet-type heat transfer tube is installed in the heat pipe, in which heat is transferred to and exchanged with the water that is guided through the piping inside the heat pipe, flows down from above, turns around at the lower end of the heat pipe, rises, and is discharged. The water flowing down the inner tube of the bayonet type heat exchanger tube is turned back at the lower end of the bayonet type heat exchanger tube, and the water flowing down the inner tube of the heat exchanger tube is arranged concentrically around the outer periphery of the inner tube of the bayonet type heat exchanger tube. The intermediate heat medium is formed to rise between the inner circumferential surface of the tube and the outer circumferential surface of the inner heat transfer tube, and the intermediate heat medium is enclosed between the outer circumference of the outer heat transfer tube of the bayonet type heat transfer tube and the inner circumference of the heat pipe. A heat exchanger for a liquid metal fast breeder reactor, characterized in that: