JPS61250402A - Steam generator - 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 Application of the Invention] The present invention relates to a steam generator, and more particularly, to an improvement of a steam generator for a fast breeder reactor that generates high-temperature, high-pressure steam by heat exchange between liquid metal and water. It is related to.

[Background of the invention]

Prior to explaining the present invention, FIG. 8 shows the overall internal structure of a steam generator for a fast breeder reactor.

In Fig. 8, 1 is the fuselage, and 2 is the water side header.

3 is a sodium side header, 4 is a heat exchanger tube, 5 is an internal shroud, and 6 is an external shroud, and the steam generator has an external structure consisting of the bodywork or the sodium side header 3,
It is roughly divided into an internal structure consisting of heat exchanger tubes 4 and an external shroud 6.

In the above configuration, during reactor operation, sodium heated to a high temperature enters the fuselage 1 from the sodium inlet nozzle 7, is distributed to a plurality of sodium distribution pipes 8, and is then helically placed on the outer periphery of the internal shroud 5. The sodium flows down around a plurality of heat exchanger tubes 9 wound in a coil shape and is discharged from a sodium outlet nozzle 10. It exchanges heat with the water flowing inside. On the other hand, the water from the water supply inlet nozzle 11 is diverted into the heat exchanger tubes 9 at the tube plate 12, and the heat exchanger tubes 9 are connected to the body 1, ! : It descends through the area formed between the outer shroud 6, bends at the lower end of the body 1, and winds the outer circumference of the inner shroud 5 in a helical shape, and then reaches the steam outlet nozzle 13. In the figure, 14 is a cover gas region formed above the internal shroud 5;
5 indicates the sodium liquid level.

The overall internal structure of a steam generator for a fast breeder reactor is as described above. Figure 9 shows the conventional basic sodium distribution pipe and its surrounding structure. The configuration is shown in FIG.

9 and 10, reference numeral 16 is located in the lower region of the sodium distribution pipe 8, and a plurality of side holes are bored in the peripheral wall of the distribution pipe 8 for sodium outflow, and 17 is the lower end of the sodium distribution pipe 8. Baffle plate 18 is attached to baffle plate 17
In the lower region of the sodium distribution pipe 8, a baffle plate 17 is provided at the lower end of the distribution pipe 8 to prevent sodium from flowing down inside the distribution pipe 8. Efforts have been made to prevent the entire flow rate of the sodium from colliding directly with the heat exchanger tubes 9 and damaging the heat exchanger tubes 9.

As a result, the high temperature water that flowed into the sodium distribution pipe 8)
Jum is connected to the inner shroud 5 and the outer shroud 6 through the side hole 16 of the distribution pipe 8 and the bottom hole 18 of the baffle plate 17.
However, at the lower end of the sodium distribution pipe 8, the sodium flowing down inside the distribution pipe 8 collides with the plate surface of the baffle plate 17. The sodium flowing from the side hole 16 formed in the peripheral wall of the one-way pipe 8 becomes faster as it approaches the baffle plate 17&C.

By the way, the side hole 1 bored in the peripheral wall of the sodium distribution pipe 8
6 and the flow rate of sodium flowing out from the bottom hole 18 formed in the baffle plate 17 becomes a high-speed flow.

It has been widely known in the art that various undesirable problems occur in steam generators, one of which is the fluid behavior in which the gas present in the cover gas region 14 is entrained in the sodium. be able to point out problems.

That is, when the sodium flowing down inside the sodium distribution pipe 8 is ejected horizontally from the side hole 16 bored in the peripheral wall of the distribution pipe 8 and collides with the internal shroud 5 and the external shroud 6, a part of it is Each flow rises along the wall it collides with. When a portion of the sodium rises in this manner, as shown in FIG. 9, the sodium liquid level 15 exhibits a large heaping phenomenon, and finally separates from the walls of the inner shroud 5 and outer shroud 6.
The sodium falls into the sodium near the sodium distribution pipe 8, and at this time, the gas in the cover gas area 14 is engulfed in the sodium and generates bubbles. Not only does this impede good heat exchange between sodium and water, which occurs through the sodium chloride, but it also adversely affects the operation of the sodium circulation pump, such as cavitation phenomena.

The second undesirable problem when the flow rate of sodium flowing out from the sodium distribution pipe 8 is a high-speed flow is:
Fluid vibration of the heat exchanger tube 9 can be mentioned.

That is, when sodium flowing down inside the sodium distribution pipe 8 is ejected from the bottom hole 18 of the baffle plate 17 in the vertical direction and collides with the heat exchanger tube 9, a vortex is generated near the heat exchanger tube 9. Therefore, when the generation period of the vortex generated near the heat exchanger tube 9 takes a value close to the natural frequency of the heat exchanger tube 9, the heat exchanger tube 9 vibrates.

Since there is a risk that the mechanical strength of the heat exchanger tubes 9 may be impaired due to so-called fluid vibration phenomenon, it is necessary to take care to prevent fluid vibrations from being applied to the heat exchanger tubes 9 as much as possible from the perspective of ensuring the safety of the steam generator. Become.

Figures 11 and 12 are vertical cross-sectional views of the sodium distribution pipe and its vicinity in a conventionally proposed fake steam generator.

In FIG. 11, the same reference numerals as in FIGS. 9 and 10 indicate the same parts, that is, 5 is the internal shroud.

6 is an outer shroud, 8 is a sodium distribution pipe, 9 is a heat transfer tube wound in a helical coil around the outer periphery of the inner shroud 5, 14 is a cover gas region formed above the inner shroud 5, 15 is a sodium liquid level 1st
In the steam generator shown in Figure 1, the sodium distribution pipe 8
A dip plate 19 for preventing gas entrainment and a sodium rectifying plate 20 are installed in upper and lower two stages, respectively, located near the lower end of the tank.

According to the steam generator shown in FIG.

This prevents undesirable problems when the flow rate of sodium flowing out from the sodium distribution pipe 8 is a high-speed flow, that is, entrainment of the gas existing in the cover gas region 14 into the sodium, and further fluid vibrations applied to the heat transfer tube 9. Although it is predicted that it will be somewhat effective in preventing this, on the other hand,
dip play) 19 and sodium rectifier plate 20,
It requires accurate drilling for the sodium distribution pipe 8 and the rising portion 9a of the heat transfer tube to pass through, and complicated assembly work, and the welding and support installation accompanying the above assembly work must be performed in a narrow space. must also be taken into account.

Next, in the steam generator shown in FIG. 12, the same reference numerals as in FIGS. 9 to 11 refer to the same parts, that is, 5 indicates an internal shroud and S6 indicates an external shroud.

8 is a sodium distribution pipe, 9 is a heat exchanger tube wound in a helical coil shape around the outer periphery of the inner shroud 5, 14 is a cover gas region formed above the inner shroud 5, and 15 is the sodium liquid level. In the steam generator shown in FIG. 12, a cone 21 is provided, which is located at the lower end opening of the sodium distribution pipe 8 and discharges the sodium flowing down inside the distribution pipe 8 obliquely downward. The details are described in Japanese Patent Publication No. 54-26643.

According to the steam generator shown in FIG.

To eliminate the problem that sodium flowing down inside the sodium distribution pipe 8 is ejected horizontally and collides with the inner shroud 5 and the outer shroud 6, and a part of it rises along the peripheral walls of the inner shroud 5 and the outer shroud 6. Although it is effective in preventing the gas present in the cover gas region 14 from being entrained in the sodium,
It is not recognized that a portion of the sodium flowing down inside the sodium distribution pipe 8 collides with the heat exchanger tube 9 and causes fluid vibration in the heat exchanger tube 9.

[Purpose of the invention]

The present invention was made as a result of various studies in order to solve the above-mentioned problems of the prior art.The purpose of the present invention is to reduce the flow rate of liquid metal flowing out from the liquid metal distribution pipe into a high-speed flow. It is possible to effectively prevent the problems that arise when the gas is present in the cover gas region, that is, the entrainment of the gas in the liquid metal, and furthermore, the fluid vibration against the heat transfer tube, and the structure is simple and compact. It is an object of the present invention to provide an improved steam generator that is easy to assemble.

[Summary of the invention]

In order to achieve the above object, the present invention introduces a liquid metal as a heating medium into a steam generator body, and in a structure of a steam generator in which the liquid metal and water are heat exchanged in the body, the liquid metal is introduced into a steam generator body. It is located in the lower region of the liquid metal distribution pipe introduced into the steam generator body, and has a side hole bored in the peripheral wall of the distribution pipe for liquid metal outflow, and is located in the lower region of the liquid metal distribution pipe. A plurality of baffle plates are provided, each having a bottom hole for liquid metal outflow. The center of the hole in one baffle plate is offset from the center of the hole in another baffle plate adjacent thereto, and the holes are bored in each baffle plate.

[Embodiments of the invention]

Hereinafter, the present invention will be explained based on an embodiment shown in FIGS. 1 to 4. FIG. 1 is a vertical cross-sectional view of the vicinity of the sodium pipe, which is the main part of the present invention, and FIG. Partially enlarged view, Figure 3 is a sectional view taken along line A-A in Figure 2, Figure 4 is B in Figure 2.
-B sectional view.

In FIGS. 1 to 4, the same reference numerals as in FIGS. 8 to 12 refer to the same parts, that is, 5 is the internal shroud, and 6 is the internal shroud.
8 is an outer shroud; 8 is a sodium distribution pipe; 9 is a heat exchanger tube wound in a helical coil around the outer periphery of the inner shroud 5; and 14 is a cover gas region formed above the inner shroud 5.

15 is the sodium liquid level, 16 is located in the lower area of the sodium distribution pipe 8, and multiple holes are bored in the circumferential wall of the distribution pipe 80). The installed baffle plate 18 indicates a plurality of holes drilled in the baffle plate 17 for outflow of IJ sodium. Another baffle plate 22 is provided inside the tube.

Reference numeral 23 denotes a bottom hole for sodium outflow, which is bored in the baffle plate 22 located inside the sodium distribution pipe 8.

The center of the bottom hole 18 bored in the baffle plate 17 and the center of the bottom hole 23 bored in the baffle plate 22 do not coincide, and both the holes 18 and 23 are located in the axial direction of the sodium distribution pipe 8. In the illustrated embodiment, the bottom hole 18 of the baffle plate 17 located at the lower end of the sodium distribution pipe 8 is in an offset relationship with respect to the
The total area of the opening is made larger than that of the bottom hole 23 of the baffle plate 22 located inside the distribution pipe 8.

In the above configuration, during reactor operation, sodium heated to high temperature is distributed from the sodium inlet nozzle (not shown) to multiple IJum distribution pipes 8, and is distributed in a helical coil shape around the outer periphery of the internal shroud 5. The sodium flows down around a plurality of wound heat exchanger tubes 9, and when flowing down around the heat exchanger tubes 9, it exchanges heat with water flowing inside the heat exchanger tubes 9.

Therefore, in the above series of sodium-water heat exchange systems, IJum flows down inside the sodium distribution pipe 8) and is discharged horizontally from the side hole 16 bored in the peripheral wall of the distribution pipe 80. Bottom hole 2 bored in baffle plate 22
3 in the vertical direction, but in FIGS. 1 and 2.

The sodium flowing down inside the sodium distribution pipe 8 collides with the baffle plate 22 located inside the distribution pipe 8, and a part of it collides with the baffle plate 22 located inside the distribution pipe 8.
The baffle plate 22 is inserted into the baffle plate 22 through the bottom hole 23 bored in the baffle plate 22.
and another baffle plate 17.
4 at a low flow rate and high flow velocity, and the other sodium flow near the upstream portion of the baffle plate 22 (indicated by 25).

The sodium is discharged horizontally from a side hole 16 bored in the peripheral wall of the sodium distribution pipe 8. Small flow rate from the bottom hole 23 of the baffle plate 22.
Sodium is flowing down at a high flow rate.

Next, it collides with another baffle plate 17 located at the lower end of the sodium distribution pipe 8, and is converted into static pressure within the pressure conversion chamber 24 between the baffle plates 22 and 17. The sodium converted to a low flow rate is discharged vertically in the direction of the heat transfer tube 9 from the bottom hole 18 bored in the baffle plate 17, and horizontally from the side hole 16 bored in the peripheral wall of the sodium distribution pipe 8. It is discharged.

The present invention is as described above, and according to the present invention.

The flow rate of sodium discharged horizontally from the side hole 16 bored in the peripheral wall of the sodium distribution pipe 8 is determined by the flow rate of the sodium discharged from the baffle plate 22 located inside the sodium distribution pipe 8 and the baffle plate 17 located at the lower end of the sodium distribution pipe 8. Pressure conversion chamber 2 formed between
4, the value can be suppressed to a sufficiently small value. Therefore, the impinging flow of sodium discharged from the side hole 16 of the sodium distribution pipe 8 against the internal shroud 5 and the external shroud 6 is small, and (n) the swelling phenomenon of the IJium liquid level 15 is also small, so that the cover gas area 14 can be effectively prevented from being entrained in the sodium.

Furthermore, in the present invention, the bottom hole 18 formed in the baffle plate 17
The flow rate of sodium discharged in the vertical direction from the pressure conversion chamber 24 can be suppressed to a sufficiently small value by the presence of the pressure conversion chamber 24. Therefore, in order to make the steam generator more compact, the lower end of the sodium distribution pipe 8 and Even if the distance from the upper end of the heat exchanger tube 9 is reduced, fluid vibrations will not occur in the heat exchanger tube 9.

Furthermore, in the present invention, all of the means for achieving the above two effects are provided in the IJum distribution pipe 8, and which cause interference with or interference with many of the devices that make up the steam generator. Moreover, since the structure is extremely simple, there are no particular difficulties in assembling this type of equipment.

Note that in the present invention, a side hole 16 drilled in the peripheral wall of the sodium distribution pipe 8 and a bottom hole 18 bored in the baffle plate 17. Furthermore, it is optional to adjust the opening area of the bottom holes 23 formed in other baffle plates 22 as appropriate.
．． By adjusting the opening areas of 18 and 23 to make the upstream portion 25 of the baffle plate 22 and the inside of the pressure conversion chamber 24 approximately equal in pressure, all the side holes bored in the peripheral wall of the sodium distribution pipe 8 are The flow rate of sodium discharged from 16, 16, . . . can be set to approximately the same value. In addition, the bottom hole 18 of the baffle plate 17 located at the lower end of the sodium distribution pipe 8,
More specifically, a plurality of bottom holes 18 are formed in the baffle plate 17.
．． The total area of the openings in 18...

If the bottom hole 23 of the baffle plate 22 located inside the distribution pipe 8 is set larger than the bottom hole 23 of the baffle plate 17, the bottom hole 18°18...
The flow rate of sodium discharged from the tube is significantly reduced.

5 to 7 each show other embodiments of the present invention). In the embodiment shown in FIG. , a case is shown in which two baffle plates 22' and 22'' are provided between the vertical side holes 16, 16 formed in the peripheral wall of the distribution pipe 8.

In addition, in the embodiment shown in FIG. 6, the sodium distribution pipe 8
By making the cross-sectional shape of the baffle plate 17 located at the lower end polygonal, the sodium discharged from the bottom holes 18, 18, etc. does not flow down only in the vertical direction, but also flows diagonally downward, and the sodium A case is shown in which the flow direction is expanded to enable flux dispersion to the heat transfer tubes located below.

Furthermore, in the embodiment shown in FIG. 7, by making the cross section of the baffle plate 17 located at the lower end of the sodium distribution pipe 8 semispherical, the bottom hole 18.18
The case is shown in which the sodium discharged from ... does not flow only in the vertical direction, but also flows diagonally downward.

〔Effect of the invention〕

The present invention is as described above, and as is clear from the description of the illustrated embodiment, according to the present invention, there are problems when the flow rate of the liquid metal flowing out from the liquid metal distribution pipe is a high-speed flow,
In other words, it is possible to effectively prevent the gas present in the cover gas region from being entrained in the liquid metal, and furthermore, the fluid vibration against the heat transfer tube, and the structure is simple and compact, and the assembly workability is good. An improved steam generator can be obtained.

[Brief explanation of drawings]

Figures 1 to 4 show an embodiment of the steam generator according to the present invention, and Figure 1 is a longitudinal cross-sectional view of the vicinity of the IJum distribution pipe. A partially enlarged view of Figure 1,
FIG. 3 is a sectional view taken along the line AA in FIG. 2. FIG. 4 is a sectional view taken along line BB in FIG. 2, FIGS. 5 to 7 are longitudinal sectional views of a sodium distribution pipe showing other embodiments of the present invention, and FIG. 8 is an overall view of the steam generator. Fig. 9 is a vertical cross-sectional view showing the internal structure of a conventional IJ.
Figure 10 is a partially enlarged view of Figure 9, and Figures 11 and 12 are a longitudinal cross-sectional view of the sodium distribution pipe and its vicinity in a conventionally proposed improved steam generator. FIG. 1...Steam generator body, 2...Water side header, 3...
・Sodium side header, 4... Heat exchanger tube, 5... Internal shroud, 6... External shroud, 7... Sodium inlet nozzle, 8... Sodium distribution pipe, 9...
Heat exchanger tube, 10... Sodium outlet nozzle, 11...
Water supply inlet nozzle. 12...Tube plate, 13...Steam outlet nozzle, 14...
・Cover gas area, 15... Sodium liquid level, 16.
...Sodium outflow side hole, 17...Baffle plate, 18.
・Bottom hole for sodium outflow, 22.22' and 22"
...Baffle plate, 23...Bottom hole for sodium outflow, 24
...Pressure Fig. 1 Fig. 8rXJ No. to 5i] Fig. 11

Claims (1)

[Claims] 1. In a structure of a steam generator in which a liquid metal as a heating medium is introduced into a steam generator body and heat is exchanged between the liquid metal and water within the body, the liquid metal is introduced into a steam generator body. located in the lower region of the liquid metal distribution pipe introduced into the body, a side hole for liquid metal outflow is bored in the peripheral wall of the distribution pipe, and located in the lower region of the liquid metal distribution pipe, respectively. In addition to being equipped with multiple baffle plates with bottom holes for liquid metal to flow out,
The bottom holes drilled in each baffle plate above for liquid metal outflow are arranged so that the center of the hole in one baffle plate is offset from the center of the hole in the other baffle plate adjacent to it with respect to the axial direction of the liquid metal distribution pipe. A steam generator characterized in that each baffle plate is provided with a hole in each baffle plate. 2. In the invention described in claim 1, among the plurality of baffle plates located in the lower region of the liquid metal distribution pipe,
The bottom hole of the lowest baffle plate has a larger total opening area than the bottom holes of other baffle plates adjacent to it. 3. In the invention described in claim 1 or 2, the cross-sectional shape of the lowest baffle plate among the plurality of baffle plates located in the lower region of the liquid metal distribution pipe is
A steam generator that is a polygon that projects downward. 4. In the invention described in claim 1 or 2, the cross-sectional shape of the lowest baffle plate among the plurality of baffle plates located in the lower region of the liquid metal distribution pipe is
A steam generator that has a hemispherical shape that projects downward.