JPS5918490A - Gas-water separator for bwr type reactor - 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 [Technical Field of the Invention] The present invention relates to a steam-water separator that separates a two-phase flow of water and steam flowing out from the core of a boiling water nuclear reactor into water and steam.

[Technical background of the invention]

Generally, a boiling water nuclear reactor is constructed as shown in FIGS. 1 to 3. In the figure, 1 is a reactor pressure vessel, and a shroud 2 is provided within this reactor pressure vessel 1, and a reactor core 3 is accommodated within this shroud 2.
A control rod drive mechanism 4 is provided in the lower part of the reactor pressure vessel 1.
..., the κ control rod (not shown) is inserted into the core 3,
It is configured to be pulled out. The coolant (light water) is then boiled within this reactor core s and flows to the 7 EU loud head 6 as a two-phase flow of water and steam. A steam separator L and a steam dryer 7 are provided above the shroud head 5.
is provided. Then, the two-phase flow of water and steam is separated into water and steam by the steam separator j, and the separated steam is dried in the steam dryer 7 and then passed through the main steam pipe from the main steam nozzle 8.8. The information is configured to be sent to a turbine (not shown) via the computer. Further, the separated water is mixed with the water supplied from the water supply sparger 9 and is mixed with the water supplied from the water supply sparger 9.
... is sent to the lower part of the reactor core 3 and is configured to circulate.

The steam and water separators are constructed as shown in FIGS. 2 and 3. Reference numerals 11, . . . are stand pipes, and these stands, f ino 11, . At the upper ends of these stands/quantity tubes 11..., the steam/water separation cylinders 12...
is provided. These steam/water separation cylinders 12...removal M
It has a double structure of a l l s and an inner cylinder 14, and a rotating barrel 15 is provided inside the inner cylinder 14. A guide blade 16 is provided at the lower end of this rotating body 5, and the above-mentioned stand and guide blade 16 are provided at the lower end of this guide blade 16.
The upper end of Yai f11 is connected. Then, the two-phase flow rising from inside the shroud head 5 through the above-mentioned stunt nozzle 4 is turned into a swirling flow by the swirling vanes 16, υ,
It is configured to be separated into water and steam by centrifugal force within the rotating body 15. Note that the solid line arrows in FIG. 2 indicate the flow of water, and the broken line arrows indicate the flow of steam.

[Problems with background technology]

When the two-phase flow of water and steam passes through the steam and water separators, a pressure loss occurs. By the way, when this pressure loss is large h and the flow rate is low, the flow of the coolant flowing through the reactor core 3 becomes unstable, and the control of the reactor core 3 becomes unstable. Additionally, if this pressure loss is large, the power required to circulate the coolant becomes large (and uneconomical).For this reason, it is desirable to reduce the pressure loss between the conventional steam and water separators as much as possible. In order to reduce this pressure loss, the first consideration is to reduce the pressure loss inside the steam/water separation shell 12. However, improvements have been made to the steam/water separation shell 12 in the past, and the pl. It is difficult to reduce the pressure loss any further.For this reason, the inventors of the present invention analyzed the pressure loss within the steam/water separation shell 12 and obtained the following results.

In other words, the pressure loss inside the steam/water separation shell 12 is 48% of the total], and the stand! It was found that the loss due to the original vibration resistance inside the tube 11 was only 2%, and the remaining 50% of the pressure loss occurred near the opening of the stand pipe 11 on the inner surface of the shroud head 5. The results of further investigation into this cause are as follows. That is, the state of the flow from the inside of the shroud head 5 to the inside of the stand pipe 1 is as shown in FIG. ...It depends on what flows within. For this reason, the flow was significantly contracted at the opening of the stand and flat tube, and as a result, the large pressure loss (as described above) occurred at the opening of the stand and flat tube.

[Purpose of the invention]

The present invention has been made based on the above-mentioned circumstances, and its purpose is to reduce pressure loss and to provide a boiling water atom system that can be easily implemented by making minor modifications to conventional systems. The purpose is to obtain a steam-water separator for the furnace.

[Summary of the invention]

In the present invention, the inner diameter of the stand pipe is set to 154 mm or more and 174 mm or less, and the diameter of the stand pipe NQ portion is continuously expanded.

The inner diameter of the above stand/I-eve is the same as that of the conventional stand.
The inside diameter of the stand pipe is larger than the inside diameter (and this is within a range where it is not necessary to change the arrangement pitch of the stand pipe, etc.).Therefore, as the inside diameter of the stand pipe becomes larger, the ratio of trickle in the two-phase flow of coolant decreases. As the stand pipe is small, the pressure loss at the opening part of this stand can be greatly reduced, and it can be implemented by just making minor modifications to the conventional one.In addition, #S of the opening part of the stand pipe can be continuously Since the diameter has been enlarged, the flow at this edge is not dragged, and the pressure loss at the stand/quantity tube opening can be further reduced.

61 [Embodiment of the Invention] An embodiment of the present invention will be described below with reference to FIGS. 4 to 7.

In the figure, 101 is a reactor pressure vessel, and a shroud 1θ2 is provided inside this reactor pressure vessel 101.
A reactor core 103 is housed within this shroud 102 . Control rod drive mechanisms 104 are provided at the bottom of the reactor pressure vessel 101, and control rods (not shown) are inserted into the reactor core 103 by these control rod drive mechanisms 104. It is configured to be pulled out. The coolant (light water) is then boiled within this core ios and flows to the shroud head 105 as a two-phase flow of water and steam. A steam separator 106 and a steam dryer 10F are provided above the shroud head 105. The two-phase flow of water and steam is the above-mentioned steam/moisture M unit 1.
06, the separated steam is dried in a steam dryer 107, and then transferred to the main steam nozzle 108.10.
8 through a main steam pipe to a turbine (not shown). Further, the separated water is mixed with the water supplied from the water supply spacer 109, and is sent to the lower part of the reactor core 103 by the shet pumps 110 and circulated.

The steam/water separator 106 is constructed as shown in FIGS. 2 and 3. 111... is stand f
These stands f111, . . . project from the shroud spatula P1os, and their lower ends open into the shroud head 105. A steam/water separation cylinder 111 is provided at the upper end of each of these stands, f111, and so on. These steam/water separation cylinders 112... have a double structure of an outer cylinder 113 and an inner cylinder 114, and inside this cylinder 114 there is a rotating cylinder 11.
5 is provided. A guide vane 116 is provided at the lower end of this rotating body 115, and the upper end of the above-mentioned stand and f-beam 111 is connected to the lower end of this guide vane 116. Then, the two-phase flow rising from the inside of the shroud head 105 through the above-mentioned stand/volume 11 is turned into a swirling flow by the swirling vanes 116, and the swirling body 1
15, water and steam are separated by centrifugal force. Note that the solid arrows in FIG. 5 indicate the flow of water, and the dashed arrows indicate the flow of steam.

The inner diameter Dz of the stunt knife 4-beam 111 is 15
It is set in the range of 4m+ to 174tutt. Further, the edge of the opening of the stand pin on the inner surface of the shroud head 105 is formed into an arcuate cross section, and a rounded portion 117 is formed.
. . . These stand-up openings are continuously enlarged in diameter toward the inside of the shroud head 105.

Next, the operation of this embodiment will be explained. The two-phase flow of water and steam flowing out of the reactor core 103 flows from the shroud head 105 into each standpipe f1 horn, flows upward in these standpipes 11, and passes through the steam and water separation shell. At 112..., the water is separated into water and steam. Then, from inside the shroud head 105, stand tape 11...
When a two-phase flow flows within the shroud head P105, the two-phase flow flowing into one stunt pipe 111 flows within a range of D% within the shroud head P105, so a contracted flow occurs at this shroud head opening. The pressure loss ΔP in such a case is
The inner diameter of the stand pipe 111 is D2, and AI = 7DI (Cross-sectional area of the flow path in which the two-phase flow of stunt no.4, f1, and p flows in the shroud head) The volumetric flow rate of the two-phase flow is QT%, the gravitational acceleration is g, and the loss coefficient determined by the shape of the opening of the stand is α, the coefficient for converting into KBs. Become a bastard. Here, if we consider the pressure loss coefficient, we get: Therefore, the larger the ratio of M3/Ml is, the smaller the pressure loss coefficient ζ becomes. And this thing is a stand/f
The inner diameter D2 of the ignition 11 is larger than the conventional 154m, so A2/input l becomes larger, so this stand
9 Pressure loss at the opening is significantly reduced. but,
If D2 is made too large, the following problems will occur.

That is, these stands/f-bums 11 are arranged at relatively small intervals, and the shroud head 105
is welded to the top surface. Therefore, these stands
If the diameter of the f-b 11 is increased by p, the gap between the stand vias 1J7 will be small, making p1 welding difficult. Also, these stands Zoib 11...
If the diameter is made too large, the relationship with the diameters of the guide vanes 116 and the rotating body 1/5 will change, resulting in problems such as changes in characteristics and conversely increased pressure loss. So, stand?
The diameter of the tubes 111 is limited by these conditions, and the maximum outer diameter of the stand f tubes 111 is 180 mm. The wall thickness of the stunt no. 9 Eve 111... must have at least three ridges due to strong deformability, so the maximum value of the inner diameter D2 of these stunt no. 9 Eve 111... is 174111.
It is 1. Therefore, if the inner diameter of the stand, 9if, 111... is set in the range of 154mm to 174mm, the effect of reducing pressure loss can be obtained, and there is no need to make any major design changes compared to the conventional one. , simply standpipe 111・
This can be easily done by simply changing the diameter of...

In addition, there is a rounded part 11 at the edge of the standpipe opening.
7... is formed, and since the diameter of this stun F''/f tube opening is continuously enlarged, the flow is not disturbed at this edge, and the pressure loss can be further reduced. If the radius of the radiused portion iir... is less than 5III+, a sufficient effect of reducing pressure loss cannot be obtained, and the radius is limited to 30114 or less due to the thickness of the shroud head 105, etc., so a range of 5 m to 301 Eil is preferable.

Note that FIG. 7 shows the above effect. This Fig. 7 shows the relationship between the inner diameter and pressure loss coefficient of the stand, f-ib 111, etc., and the solid line shows the case where the rounded part with a radius of 25mm is completely formed at the edge of the stand/f-ino opening. , the broken line indicates that no rounded portion is formed. As is clear from FIG. 7, when the inner diameter of the stand pipe 111 is increased, the pressure loss coefficient becomes smaller, and
It is shown that the pressure loss coefficient becomes smaller when K is formed.

〔Effect of the invention〕

As mentioned above, the present invention has an inner diameter of 15411 mm.
111 m or more and 174 m or less, and the diameter of the opening of the stand/mother's eve is continuously enlarged. The inner diameter of the stand/f-shaped tube is p larger than the inner diameter of the conventional stand/f-shaped tube, and is within a range where it is not necessary to change the arrangement pitch of the stand/f-shaped tube. Therefore, by increasing the inner diameter of the standpipe, the ratio of condensation in the two-phase flow of the coolant becomes smaller, and the pressure loss at the opening of this standpipe can be significantly reduced, and it is possible to make minor modifications to the conventional one. It can be implemented by simply adding. In addition, since the diameter of the edge of the standpipe opening is continuously enlarged, the flow at this edge is not disturbed, and the pressure loss at the standpipe opening can be further reduced. It is.

[Brief explanation of drawings]

1 to 3 show a conventional example, in which FIG. 1 is a longitudinal sectional view, FIG. 2 is a longitudinal sectional view of a steam/water separation cylinder, and FIG. 3 is a longitudinal sectional view of an opening portion of a standpipe. 4 to 7 show an embodiment of the present invention, in which FIG. 4 is a longitudinal sectional view, FIG. 5 is a longitudinal sectional view of the steam/water separation shell, and FIG. f-i! FIG. 7, which is a longitudinal cross-sectional view of the open bottom portion, is a diagram showing the relationship between the stand/f-veh inner diameter and the pressure loss coefficient. 101... Reactor pressure vessel, 102... Shroud, 103... Reactor core, 105... Shroud head,
106... Steam/water separator, 11... Stand via, 112... Steam/water separation cylinder, 117... R section. Applicant's agent Patent attorney Takehiko Suzue 14- Japanese Patent Application Publication No. 1884-18490 (5)

Claims (2)

[Claims] (1) The above-mentioned stand is equipped with a plurality of stand pipes projecting from the shroud head and opening into the shroud head, and a steam/water separation shell attached to the upper ends of these stans l-' and f-tubes. A steam-water separator for a boiling water reactor, characterized in that the inner diameter of the pipe is 154 m or more and 174 m or less, and the edge of the stand pipe opening on the inner surface of the shroud head is continuously expanded. (2) A patented water separator characterized in that the edge of the standpipe opening portion is formed into an arcuate cross section.