JPS61130797A - Intermediate heat exchanger - Google Patents

Abstract

PURPOSE:To alleviate the stress producing in a discontinuous part around a pipe header, by joining a surrounding outer shell and a down-pipe to the pipe header provided in an inner shell, on the intermediate surface area of a pipe heater. CONSTITUTION:An upper header plate 10 is joined to the side wall of a downcomer or a riser pipe 18 and to the inside wall of an outer shell 8 by fitting parts 23 and 24 respectively on the intermediate surface area 22 as shown by a dotted line. A lower pipe header 11 is joined to the inside wall of an inner shell 9 on the intermediate surface area 22, and is also joined to the side wall of a downcomer or a riser pipe 18 by fitting parts on the intermediate surface area in the same manner. The joining part has a smooth curve on the intermediate surface area 22 of each header plate 10 or 11, joined to the outer shell 8, or the downcomer or the riser pipe 18, interposed by fitting parts. The primary cooling medium in high temperature, flowing along the outer walls of heat transfer pipes 12, exchanges heat with the secondary cooling medium (b) and flows out of a nozzle 16. The secondary cooling medium (b) gets into the upper plenum chamber 20, going down through the inside of heat transfer pipes 12, exchanging heat with the primary cooling medium (a), and flows out of a nozzle 21. Only round constituents theta act on the structurally discontinuous parts (d) and (e) on the pipe header plate 10. These areas serve to join thin fitting parts 23 and 24 to thick pipe header plate 10. With such an arrangement, concentration of stress around the plate 10 can be alleviated.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to an intermediate heat exchanger for a liquid metal-cooled fast breeder reactor, and in particular, it relates to an intermediate heat exchanger for a liquid metal cooled fast breeder reactor, and in particular, a structure in which a structural discontinuity is provided at the neutral plane of a thick tube plate reduces stress. The present invention relates to an intermediate heat exchanger having a tube plate.

[Technical Background of the Invention] As shown in FIG. 4, a reactor cooling system for a colloop-type liquid metal cooled fast breeder reactor includes a primary main circulation pump 3 disposed between a reactor vessel 1 and an intermediate heat exchanger 2. , these are connected by a main pipe 4. The reactor vessel 1, intermediate heat exchanger 2, and primary main circulation pump 3 are used to store the primary coolant that leaked when the main piping 4 is damaged and to ensure the liquid level within the reactor vessel 1. , a reactor vessel guard vessel 5, an intermediate heat exchanger guard vessel 6, and a primary main circulation bomb guard vessel 7 are provided, respectively.

The intermediate heat exchanger B2 is a shell-and-tube type heat exchanger as shown in FIG. tube sheet 10
and a lower tube plate 11 are provided, and both upper and lower tube plates 10.
A large number of heat transfer tubes 12 are provided between 11. The secondary coolant flows from the primary system inlet nozzle 13 provided on the upper side surface of the outer shell 8, and flows into the inner shell 9 through the inlet window 14 provided on the upper side surface of the inner shell 9. The inflowing coolant passes through the exit window 15 provided on the lower side of the inner ll1I9.
The primary system outlet nozzle 16 installed at the lower end of the outer l519
It flows out from the main pipe 4.

On the other hand, the secondary coolant flows in from the secondary system inlet nozzle 17,
It flows into the lower plenum 19 through the downcomer pipe 18, is reversed in the plenum 19, flows from the lower tube plate 11 into the heat exchanger tubes 12, and flows out from the secondary system outlet nozzle 21 from the upper tube plate 10 through the upper plenum 2o.

[Problems in the background art] In conventional intermediate heat exchangers, when the temperature of the coolant changes rapidly during an accident such as a nuclear reactor trip, large thermal stress occurs in the structural discontinuities of the tube sheets 10 and 11, causing structural damage. It has been said that its feasibility is extremely difficult.

In order to reduce this large thermal stress, it is necessary to install a heat shield plate or a liner plate around the tube sheet to reduce the thermal stress, and the design thereof is also difficult.

[Object of the Invention] The present invention has been made in view of the above circumstances, and its purpose is to provide an intermediate heat exchanger in which stress generated in the discontinuous portions around the tube sheets 1o and ii is reduced. be.

[Summary of the Invention] That is, the present invention provides a double cylindrical shell antagonal heat exchanger in a nuclear reactor cooling system cooled by liquid metal. This intermediate heat exchanger is characterized in that the tube plates are joined at the neutral plane of the tube sheet, and the stress generated at the joint is reduced.

[Embodiment of the Invention] An embodiment of the present invention will be described below with reference to FIGS. 1 to 3. Note that the same parts in the figure as in FIG. 5 are designated by the same reference numerals.

FIG. 1 shows the structure of the intermediate heat exchanger of the present invention, and FIG. 2 shows details especially around the upper tube plate.

That is, in FIG. 1, the intermediate heat exchanger 2 is a shell-and-tube type heat exchanger in which the primary cold W material is passed through the shell side. The heat exchanger 2 includes an outer shell 8, an inner shell 9 disposed concentrically within the outer shell 8, and an upper tube plate 10 and a lower tube plate provided at both upper and lower ends of the inner shell 9. 11, a large number of heat transfer tubes 12 connecting the upper and lower tube plates 10 and 11, a primary system inlet nozzle 13 provided on the side of the outer shell 8, and a primary system outlet nozzle 16 provided at the lower end of the outer shell. And this-
The secondary system outlet nozzle 16 communicates with one lower plenum, and the rising pipe 18 is fixed to the lower tube plate 11, the secondary system inlet nozzle 17 is provided at the upper part of the outer shell 8, and the secondary system inlet nozzle 17 is provided at the lower part of the inner shell 9. An entrance window 15 provided at the top of the inner shell 8 and an exit window 14 provided at the top of the inner shell 8
and the secondary system outlet nozzle 21 provided at the top of the outer WA8.
It is composed of.

Here, as shown in an enlarged view in FIG. 2, the lower tube plate 10 is attached to the side surface of the downcomer or riser tube 18 and the inner surface of the outer shell 8 by members 23 and 24 at the neutral plane indicated by the broken line 22. has been done.

Further, the lower tube plate 11 is joined to the inner surface of the inner shell 9 at a neutral plane 22, and the side surface of the descending pipe or rising pipe 18 and the mounting member 23 are similarly joined at the neutral plane.

Roughly speaking, the joints or discontinuities in the neutral planes 22 of the tube sheets 10 and 11 have smooth curves and are connected to the outer shell 8 and the downcomer pipe or the riser pipe 18 through attachment members.

Next, the operation of the intermediate heat exchanger according to the above structure will be explained using FIG. 1 and FIG. 4.

In FIG. 4, the heat generated in the reactor vessel 1 is transported through the primary main piping 4 by the primary cooling material circulated by the main circulation bomb 3, and is transferred to the secondary cooling material in the intermediate heat exchanger 2. The primary main circulation bomb 3 returns to the reactor vessel 1 again via the main piping 4 and the primary main circulation bomb 3.

If the reactor vessel 1 and the vertical pipe 4 connected to the inlet of the reactor vessel 1 and inside the guard vessel 6 are damaged, the leaked primary coolant will be stored in the reactor vessel guard vessel 6 and the reactor The coolant level in vessel 1 is maintained at the required level.

On the other hand, in FIG. 1, the high-temperature primary coolant transported from the reactor vessel (not shown) flows in from the secondary system inlet nozzle 13 and flows outside the large number of heat transfer tubes 12 to form the secondary coolant. It exchanges heat, becomes low temperature, and flows out from the primary system outlet nozzle 16.

The secondary coolant is supplied to the upper plenum 2 through the secondary system inlet nozzle 17.
The heat exchanges heat with the primary coolant while descending inside a large number of heat transfer tubes 12, and then flows out from the secondary system outlet nozzle 21.

[Effect of the invention] The effects of the present invention will be explained using FIGS. 3 and 6.

FIG. 6 is a conceptual side view schematically showing the tube plate and its surroundings of an intermediate heat exchanger in a conventional example. As is clear from Fig. 6, the structural discontinuities, that is, the joint parts a, b, c
is the rotational displacement θ of the tube plate 1o and the forced displacement δ of the translational component at the same time.
receive. Note that m−n indicates both end portions of the neutral plane 22.

In contrast, in the tube sheet 10 shown in FIG. 3 of the present invention, only the rotational component θ acts on the structural discontinuities d and e, so that the generated stress is significantly reduced. Also, the structural discontinuity part d,
e is a smooth curved surface, and the thin-walled attachment connects the members 23, 24 and the thick-walled tube plate 10 to reduce stress concentration. In this way, in the tube plate of the intermediate heat exchanger according to the present invention, the stress generated at the structural discontinuities is reduced, so the conventional heat shield plate etc. for reducing the generated stress can be omitted. Not only will it be easier to ensure the structural integrity of the tube plate, but it can also be expected to streamline equipment.

[Brief explanation of the drawing]

FIG. 1 is a vertical sectional view showing an embodiment of an intermediate heat exchanger according to the present invention, FIG. 2 is an enlarged vertical sectional view showing the circumference of the tube plate in FIG. 1, and FIG. Fig. 4 is a system diagram showing a conventional reactor cooling system, Fig. 5 is a longitudinal sectional view showing a conventional intermediate heat exchanger, and Fig. 6 is a conceptual diagram for explaining the action of the i-tube plate in the 6 is a conceptual diagram for explaining the action of the tube plate in FIG. 5. FIG. 1...Reactor vessel 2.2a, 2b...Intermediate heat exchanger 3...-Main circulation pump 4.4a...-Transmission pipe 5...Reactor vessel guard vessel 6...・Guard vessel 7 for intermediate heat exchanger - Guard vessel 8 for main circulation pump...Outside
9...Inner trunk io, ii...Upper and lower tube plates 12...
・Heat transfer tube 13... - Secondary system inlet nozzle 14... Entrance window 15... Outlet window 16...
-Secondary system outlet nozzle 17...Secondary system inlet nozzle 18...Downcomer or riser pipe 19...Lower plenum 20...Upper plenum 2
1...Secondary system outlet nozzle 22...Neutral surface 23.24...Installation is shown in Figure 1

Claims (2)

[Claims] (1) an outer shell, an inner shell disposed concentrically with the outer shell, a downcomer or riser pipe disposed within the inner shell, and a descender pipe or riser pipe disposed within the inner shell; a large number of heat transfer tubes, an upper tube sheet and a lower tube sheet supporting the large number of heat transfer tubes, an upper plenum and a lower plenum provided outside the upper tube sheet and the lower tube sheet, and the outer shell and inner shell. In an intermediate heat exchanger comprising a primary nozzle and a secondary nozzle connected to An intermediate heat exchanger characterized by: (2) The intermediate heat exchanger according to claim 1, wherein the discontinuous portion in the neutral plane of the tube sheet is joined to the outer shell and the downcomer pipe or the riser pipe by a smooth curve.