JP2001041410A - Vapor dryer and nuclear power plant - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effectively remove liquid droplets even when a liquid droplet flow rate in vacuum is increased by increasing a heat output. SOLUTION: The present vapor dryer includes a corrugated panel in which a bent flow passage is provided for capturing liquid droplets from vapor flowing in the flow passage, and a perforated plate through which many through-holes are formed for equalizing vapor. Herein, there are disposed an upper stream side corrugated panel section 77 on an upstream side in the flow direction of vapor and a downstream side corrugated panel section 78 on a downstream side. An inlet perforated plate 71 is provided between the upstream side corrugated panel section 77 and the downstream side corrugated panel section 78. An outlet perforated plate 73 is installed on the vapor outlet side of the downstream side corrugated panel section 78.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a steam dryer for taking in steam from a steam separator of a nuclear reactor and removing droplets contained in the steam, and a nuclear power plant in which the steam dryer is installed. .

[0002]

2. Description of the Related Art A nuclear power plant is provided with a steam / water separation system including a steam / water separator and a steam dryer in order to maintain the soundness of a steam turbine. The steam separator separates the steam generated by the heating of the reactor from the cooling water, and the steam dryer removes droplets from the separated steam.
Then, steam whose droplet amount has been adjusted to a certain value or less by the steam dryer is supplied to the steam turbine.

FIG. 15 shows an example of a nuclear power plant equipped with such a steam-water separation system. FIG. 15 is a longitudinal sectional view of the improved boiling water reactor, in which a reactor core 2 is installed in a shroud 3 inside a reactor pressure vessel 1. Core 2
Then, steam is generated, and the steam flows in a mixed state with the cooling water through the upper plenum 8 into the steam-water separators 12 installed in the shroud head 4, where the steam containing the droplets and the cooling water are mixed. And separated. The separated cooling water is mixed with the water supplied from the water supply pipe 10, passes through the downcomer 5, is driven by the internal pump 6, and is recirculated to the core 2 via the lower plenum 7. On the other hand, the steam containing the droplets is supplied to a steam turbine (not shown) via the main steam pipe 9 after the droplets are removed by the steam dryer 50, and the steam turbine is rotated to rotate the generator. Drive. The steam that drives the steam turbine and the generator to rotate passes through a condenser and a feedwater heater (not shown), and is thereafter supplied from the feedwater pipe 10 into the reactor pressure vessel 1.

FIG. 16 is a longitudinal sectional view showing the detailed structure of the steam dryer 50, and FIG. 17 is a sectional view taken along line AA of FIG. About 99% of the cooling water that flows in the steam separator 12
The above is separated and drained. The cooling water of less than 1% is included in steam as droplets and flows into the steam dryer 50. The dashed arrow a in the figure indicates a vapor stream containing such droplets. The steam containing the droplets flows into the steam dryer unit 700 mainly including the inlet perforated plate 71, the corrugated plate portion 55, and the outlet perforated plate 73 via the inlet flow path 52 inside the hood 51. The droplet having a large momentum that has passed through the entrance porous plate 71 collides with the side wall of the bent channel 55A of the corrugated plate portion 55,
A liquid film is formed and flows from the slit 55B into the pocket 55C. The droplets flowing into the pocket 55C flow down in the pocket 55C due to gravity, and are collected in a drain gutter 75. Drained in between. On the other hand, the steam from which the droplets have been removed by the corrugated plate portion 55 passes through the outlet perforated plate 73, passes through the outlet channel 53 outside the hood 51, passes through the main steam pipe 9 in FIG. Supplied to

[0005] In this way, about 99% of the droplets flowing into the steam dryer 50 are removed. That is, steam-water separator 1
2 flows into the steam-water separator 12 to about 1/100
In addition, the amount is reduced to about 1 / 10,000 by the steam dryer 50. Extremely good steam-water separation performance of about 0.01% is realized against the limit value of 0.1% or less of the outlet moisture (the ratio of the mass flow rate of the droplets contained in the steam) in the main steam pipe 9. I have. In a boiling water reactor that supplies steam generated in the reactor core 2 to a steam turbine, it is also necessary to reduce radioactive substances contained in cooling water (droplets) and reduce the radiation level of the steam turbine system. Maintaining good water-water separation performance is extremely important. Although the current steam dryer 50 has extremely high droplet removal performance, the amount of droplets at the inlet is limited and cannot be handled if the amount of droplets from the steam separator 12 is significantly increased.

[0006] On the other hand, there is a strong demand for a reduction in electricity rates, and in nuclear power plants with low fuel costs and high construction costs, a significant reduction in the construction unit price (construction cost divided by power generation amount) is required. The most effective means for reducing the unit construction cost is to increase the heat output and power generation of the core 2. In this case, it is necessary to increase the flow rate of the cooling water in order to cool the core 2, and the amount of steam generated in the core 2 also increases due to the increase in the heat output. When the steam generation amount and the steam flow rate increase, the performance of the steam dryer 50 decreases and the outlet moisture increases, so that the performance of the steam dryer 50 needs to be improved.

[0007] Known techniques for improving the droplet capturing performance of a steam dryer include, for example, those described in JP-A-8-338605 and JP-A-9-79502.
In these known techniques, the corrugated plate portion is made one or two steps to reduce the size of the corrugated plate portion. That is, FIG.
As shown in the above, the corrugated plate part used to be I-IV in four steps, but this is made one or two steps to reduce the size of the corrugated plate part so that more corrugated parts can be installed. ing. As a result, the inlet area is enlarged, the steam flow rate is reduced, the breakthrough condition in which the outlet moisture increases sharply is improved, and the angle of the corrugated sheet is increased to improve the droplet capturing performance.

[0008]

However, the above-mentioned Japanese Patent Application Laid-Open No. 8-338605 and Japanese Patent Application Laid-Open No. 9-79502.
In the steam dryer disclosed in the publication, when the heat output of the core is increased and the amount of generated steam is increased, the flow rate of droplets in the steam is also increased and the outlet moisture is increased. As a result, there is a problem that it is difficult to maintain the soundness of the steam turbine.

An object of the present invention is to provide a steam dryer capable of efficiently removing droplets even if the flow rate of the droplets in the steam is increased by increasing the heat output, and the steam dryer is installed. To provide a nuclear power plant.

[0010]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a liquid droplet capturing section provided with a curved flow path, which captures liquid droplets from vapor flowing through the flow path, and a plurality of through holes. In a steam dryer provided with a plurality of perforated plates that are formed with holes and rectify the vapor in the droplet capturing section, while dividing the droplet capturing section into an upstream side and a downstream side along the flow direction of the vapor,
A steam dryer in which one of the perforated plates is interposed between the upstream droplet capturing unit and the downstream droplet capturing unit, and the upstream droplet capturing unit, the downstream droplet capturing unit, and the perforated plate are integrated. It is characterized by having a unit.

The smaller the wetness of the perforated plate inlet, the greater the function of the droplet permeating the perforated plate. Dividing the droplet capturing unit along the flow direction of the steam into the upstream side and the downstream side as in the above configuration, and interposing a perforated plate between the upstream droplet capturing unit and the downstream droplet capturing unit, As much as the droplets are captured by the upstream droplet capturing unit without the perforated plate, the wetness of the perforated plate inlet is reduced, and as a result, the droplet capturing function of the perforated plate is improved,
It is possible to improve the droplet capturing function of the entire steam dryer.

[0012] The length of the upstream droplet catching section along the flow direction of the vapor may be equal to the length of the downstream droplet catching section, or may be longer than the length of the downstream droplet catching section. Good.

In the steam dryer having the above-mentioned structure, the upstream-side droplet capturing section, the downstream-side droplet capturing section and the perforated plate are integrated, but the upstream-side droplet capturing section and the downstream-side droplet capturing section are integrated. Can be composed of separate units. That is, the present invention provides a steam dryer having the same configuration as described above, in which the droplet capturing unit is divided into an upstream side and a downstream side along the flow direction of steam, and the upstream steam dryers each having a unit structure. A unit and a downstream steam dryer unit are provided, and one of the perforated plates is attached to the steam outlet side of the upstream steam dryer unit.

When the upstream steam dryer unit and the downstream steam dryer unit are provided, the perforated plate can be attached to the downstream steam dryer unit. That is, the present invention provides a steam dryer having the same configuration as described above, in which the droplet capturing unit is divided into an upstream side and a downstream side along the flow direction of steam, and the upstream steam dryers each having a unit structure. A unit and a downstream steam dryer unit are provided, and one of the perforated plates is attached to the steam inlet side of the downstream steam dryer unit.

Further, according to the present invention, there is provided a droplet capturing section provided with a curved flow path, which captures droplets from vapor flowing in the flow path, and a rectification of vapor in the droplet capturing section, which is formed with a large number of through holes. A plurality of perforated plates, and a hood for covering the droplet capturing unit and the perforated plate and guiding vapor to the droplet capturing unit and the perforated plate, a set of droplet capturing units covered by one hood, and When the perforated plate is a single steam dryer unit, in a steam dryer in which a plurality of sets of the steam dryer units are provided, a plate-shaped outer surface of the hood is provided with a gap between the hood surface and the outer surface of the hood. A member and a droplet catching plate provided above the plate-like member for capturing liquid droplets. The steam from the adjacent steam dryer unit collides with the plate-like member, and flows along the plate-like member. Drops in the vapor are trapped by the droplet capture plate and guided into the gap It is characterized by a door.

According to the above configuration, the steam from the steam dryer unit collides with the plate-like member, rises on the plate-like member with the steam flow, and is captured by the droplet capturing plate. The captured droplet flows down the gap between the hood and the plate-like member and is discharged. As a result, the droplet capturing function is further improved, and the droplet capturing function of the entire steam dryer can be further improved. In addition, as the steam dryer unit, the upstream droplet capturing unit, the downstream droplet capturing unit, and the perforated plate may be integrated, or the upstream droplet capturing unit and the downstream droplet capturing unit may be integrated. It may be separate.

The steam dryer of the present invention can be installed in a nuclear power plant. By installing the steam dryer of the present invention, a nuclear power plant having a low outlet moisture can be realized.

[0018]

Embodiments of the present invention will be described below with reference to the drawings. (Embodiment 1) FIG. 1 is a longitudinal sectional view of a steam dryer according to Embodiment 1 of the present invention, and FIG. 2 is a sectional view taken along line BB of FIG. In the steam dryer 50 of the present embodiment, a corrugated plate serving as a droplet capturing unit is divided into an upstream side and a downstream side along a flow direction of steam. That is, the upstream corrugated plate portion 77 is disposed on the upstream side along the flow direction of the steam, and the downstream corrugated plate portion 78 is disposed on the downstream side.
An inlet perforated plate 71 is provided between the downstream corrugated plate 78 and the downstream corrugated plate 78. An outlet perforated plate 73 is provided on the steam outlet side of the downstream corrugated plate portion 78. A large number of through holes are formed in the entrance porous plate 71 and the exit porous plate 73. The upstream corrugated plate 77, the inlet perforated plate 71, the downstream corrugated plate 78, and the outlet perforated plate 73 are integrally formed to form a steam dryer unit.

The upstream corrugated plate 77 and the downstream corrugated plate 78
As shown in FIG. 2, the flow path 77 is bent in a wave shape.
A, 78A are provided, and slits 77B, 78B are formed at a plurality of locations on the side walls of the flow paths 77A, 78A. The pocket 7 is located near the flow paths 77A and 78A.
7C and 78C are provided, and the flow paths 77A and 78A are formed through the slits 77B and 78B respectively.
It communicates with 8C. The pockets 77C and 78C are shown in FIG.
Is provided in the vertical direction in the figure, and its lower tip is
It communicates with the drain gutter 75 shown in FIG.
5 is connected to a drain pipe 76.

In the above configuration, the steam-water separator 12 (FIG. 1)
5) flows into the upstream corrugated plate portion 77 via the inlet flow path 52 inside the hood 51 of the steam dryer 50, as indicated by a dashed arrow a shown in FIG. Here, a significant proportion of the droplets in the vapor are removed, and then flow through the inlet perforated plate 71 into the downstream corrugated plate portion 78 where the remaining droplets in the vapor are removed. . That is, since the droplet has a large momentum, when flowing in the flow paths 77A and 78A, the liquid droplet collides with the side walls of the flow paths 77A and 78A and collides with the flow path
A liquid film is formed on the side surfaces of A and 78A. The liquid film is formed in pockets 77C and 78C through slits 77B and 78B.
And flows down the pockets 77C and 78C by gravity to be collected in the drain gutter 75, and further through the drain pipe 76, between the steam dryer skirt 11 and the reactor pressure vessel 1 shown in FIG. Drained to

On the other hand, the vapor from which the droplets have been removed by the upstream corrugated plate portion 77 and the downstream corrugated plate portion 78 flows from the perforated outlet plate 73 through the outlet channel 53 outside the hood 51 to the main steam pipe 9.
(See FIG. 15) to the steam turbine.

By the way, conventionally, as shown in FIG.
The corrugated plate portion 55 constitutes one steam dryer unit in four stages (I to IV). In contrast, in the present embodiment,
As shown in FIG. 2, the upstream corrugated plate 77 and the downstream corrugated plate 78 are both formed in two stages (I to II), and the space between the upstream corrugated plate 77 and the downstream corrugated plate 78 is provided. The inlet perforated plate 71 is arranged at the bottom. Hereinafter, functions in the present embodiment will be described.

First, the function of the perforated plate 71 will be described. Two perforated plates, an inlet perforated plate 71 and an outlet perforated plate 73, are used, and the function of removing droplets in the vapor flow and the uniform flow velocity distribution in the height direction in the flow paths 77A and 78A are made uniform. Function as a flow resistor. In order to make the flow velocity distribution uniform, the through-holes on the inlet perforated plate 71 are formed so that the diameter becomes smaller gradually from the upper side to the lower side. It is formed so as to gradually increase downward.

FIG. 3 is an explanatory diagram of droplet capture by the perforated inlet plate 71. Some of the droplets carried by the steam flow a in FIG. 1 pass through the through-holes of the upstream entrance perforated plate 71, but the remaining droplets collide with the entrance perforated plate 71, and a part of the droplets as droplets As it re-scatters, the remainder becomes a liquid film and flows down by gravity. At this time, the liquid film flowing down
When passing through the through hole of the entrance porous plate 71, the steam is pushed downstream through the through hole by the flow of steam. When the pushed liquid film is broken by the vapor flow, droplets are generated. In other words, the smaller the ratio of the flow rate of the liquid droplet passing through the through-hole to the flow amount of the liquid droplet flowing into the inlet porous plate 71, the higher the droplet capture rate at the inlet porous plate 71. FIG.
Shows the relationship between the wetness at the entrance of the entrance porous plate 71 and the droplet capture rate. As can be seen from FIG. 3, the higher the wetness of the inlet, the smaller the droplet capture rate of the inlet porous plate 71.

Next, the droplet capture rate by the upstream corrugated plate 77 and the downstream corrugated plate 78 will be described. Regarding the capture ratio by the corrugated plate, the experimental result shown in FIG. 4 is reported to the Atomic Energy Society of Japan, "1993 Spring Annual Meeting" D23. In this experiment, a specimen having only a corrugated plate portion without using an inlet perforated plate was used. The horizontal axis shows the position in the length direction of the corrugated plate portion. The vertical axis is the relative value of the flow rate of the droplet passing through each position. Assuming that the droplet flow rate at the inlet is 1.0, the droplet flow rate is about 0.2 at the position of the first stage (portion I in FIG. 17) of the corrugated plate portion. In other words, this indicates that 0.8 droplets were captured at the first stage position. In a similar way,
At the position of the second stage (portion II in FIG. 17), 0.15 droplets are captured. At the positions of the third stage (portion III in FIG. 17) and the fourth stage (portion IV in FIG. 17), the droplet capture rate is small and the droplet flow rate is only slightly reduced. The vertical axis of FIG. 4 corresponds to the degree of wetness, and it can be seen that the degree of wetness decreases as it goes downstream of the corrugated plate portion.

FIG. 5 is an explanatory diagram of droplet capture by the steam dryer unit including the inlet perforated plate 71 and the corrugated plate portion. The horizontal axis represents the distance from the entrance porous plate 71, and the vertical axis represents the wetness at each position. A thin line indicates the wetness in the related art, and a thick solid line indicates the wetness in the present embodiment (in the drawings, referred to as the present invention; the same applies hereinafter). First, the corrugated plate portion 55 (FIG.
7), the wetness is much greater at the corrugated plate inlet than at the outlet, as described in FIG. Therefore, the corrugated plate 5
5 is small (for example, X2) as shown in FIG. 3, and the wetness of the inlet porous plate 71 is slightly reduced. In particular, the droplet capture rates at the first and second stages of the corrugated plate 55 are large as shown in FIG. Therefore, when a droplet passes through this position, the degree of wetness is greatly reduced. Since the droplet capture rates at the third and fourth stages are small as shown in FIG. 4, the wetness at this position gradually decreases.

Next, the corrugated plate portion is divided into an upstream corrugated plate portion 77 and a downstream corrugated plate portion 78, and an entrance porous plate 71
The effect on the wetness of the installation of the device will be described. Since the conventional corrugated plate portion does not have a perforated plate at the corrugated plate position, the wetness does not change at this position. Once inside the corrugated plate,
Since the droplet capture rates in the first and second stages are large as shown in FIG. 4, when the droplets pass through this position, the wetness is greatly reduced. The flow velocity distribution in the height direction at the corrugated plate is determined by the flow resistance of the through-holes of the inlet porous plate 71 and the porous plate 73. However, since the length of the upstream corrugated plate is short, the flow velocity distribution at that position is determined. Is considered to be the same as the case where the entrance porous plate 71 is placed at the corrugated plate entrance as in the prior art. Therefore, the upstream corrugated plate 7
Since the droplet capture rate at the position 7 is the same as in the prior art,
The rate of decrease in the wetness at this position is the same as in the prior art.

In the present embodiment, the perforated inlet plate 71 is provided between the upstream corrugated plate 77 and the downstream corrugated plate 78.
At this position, the wetness is much smaller than at the corrugated sheet entrance. Therefore, the perforated inlet plate 71 in the present embodiment is used.
The liquid droplet capture rate is large as shown in FIG.
1) The wetness is considerably reduced. The droplet capture rates in the third and fourth stages are the same as in the prior art.

FIG. 6 is a comparison diagram of the droplet capturing performance of the steam dryer. The outlet moisture of the steam dryer 50 increases rapidly when the steam flow rate increases or the inlet moisture increases, and exceeds the limit value of 0.1%. This is called a breakthrough, and is a condition for restricting the use of the steam dryer 50. In the steam dryer of the present embodiment, since the droplet capture rate is improved as compared with the related art, the use limitation condition can be given with respect to the increase in the inlet moisture and the steam flow rate.

As described above, according to the present embodiment, the corrugated plate is divided into the upstream corrugated plate 77 and the downstream corrugated plate 78,
Since the inlet perforated plate 71 is installed in the meantime, the outlet moisture of the steam dryer 50 can be reduced by the amount by which the droplet capture rate at the inlet perforated plate 71 is improved as compared with the related art. Further, as shown in FIG. 2, since the upstream corrugated plate portion 77 and the downstream corrugated plate portion 78 can be formed in the same shape, it is possible to make the corrugated plate portion in the same manufacturing process, which is advantageous in production. .

(Embodiment 2) FIG. 7 is a longitudinal sectional view of a steam dryer according to Embodiment 2 of the present invention, and FIG.
It is sectional drawing along the line. A feature of the present embodiment is that the upstream corrugated plate portion 77 is longer than the downstream corrugated plate portion 78.

According to this embodiment, the upstream corrugated plate 77
And the downstream corrugated plate portion 78 are different in length, so that the ease of manufacture is slightly inferior to that of the first embodiment,
1 is installed on the downstream side with low wetness, the droplet capture rate by the entrance porous plate 71 increases. For this reason,
As shown in FIG. 6, the restricted flow rate of the steam dryer 50 can be greatly increased.

(Embodiment 3) FIG. 9 is a longitudinal sectional view of a steam dryer according to Embodiment 3 of the present invention. The steam dryer unit is composed of a corrugated plate and a perforated plate. In the prior art, for example, as shown in FIG.
However, in the present embodiment, the upstream steam dryer unit 710 is provided on the upstream side in the steam flow direction.
However, a downstream steam dryer unit 720 is provided on the downstream side.

The upstream steam dryer unit 710 and the downstream steam dryer unit 720 have corrugated plates 77 and 78.
A top plate 80 is provided on the upper part of the table, and an upper plate 79 is mounted on the top plate 80. Both the upstream steam dryer unit 710 and the downstream steam dryer unit 720 are fixed on the bottom plate 82 via the support 81.

In this embodiment, an inlet perforated plate 71 is attached to the steam outlet side of the upstream steam dryer unit 710, and an outlet perforated plate 73 is attached to the steam outlet side of the downstream steam dryer unit 720. Have been.

Also in the case of the above configuration, since the inlet perforated plate 71 is arranged at a position between the upstream steam dryer unit 710 and the downstream steam dryer unit 720, the same as in the first embodiment. The operation and effect can be obtained. In addition, since the upstream steam dryer unit 710 and the downstream steam dryer unit 720 have exactly the same shape, manufacture is easy.

(Embodiment 4) FIG. 10 is a longitudinal sectional view of a steam dryer according to Embodiment 4 of the present invention. Also in the present embodiment, an upstream steam dryer unit 710 is provided on the upstream side along the flow direction of steam, and a downstream steam dryer unit 720 is provided on the downstream side. A feature of the present embodiment is that the perforated plate is not provided in the upstream steam dryer unit 710, but is provided only in the downstream steam dryer unit 720. That is, the upstream steam dryer unit 710 has no perforated plate on both the steam inlet side and the steam outlet side, but the downstream steam dryer unit 720 has the inlet perforated plate 71 on the steam inlet side. Outlet perforated plates 73 are attached to the steam outlet side, respectively.

Also in the case of the present embodiment, the inlet perforated plate 71 is arranged at a position between the upstream steam dryer unit 710 and the downstream steam dryer unit 720. Similar effects can be obtained.
In addition, since the inlet perforated plate 71 and the outlet perforated plate 73 may be attached only to the downstream steam dryer unit 720, the attaching operation is facilitated.

(Embodiment 5) FIG. 11 is a longitudinal sectional view of a steam dryer according to Embodiment 5 of the present invention, and FIG. 12 is a sectional view taken along line DD of FIG. The feature of this embodiment is that the outlet channel of the steam dryer is improved.
That is, in the present embodiment, the pick-off plate 91 as a droplet capturing plate is attached to the upper end portion and the intermediate portion of the outer surface of the hood 51. A plate-like member 92 is provided below the pick-off plate 91 so as to be curved along the hood 51 and to have a gap between the pick-off plate 91 and the outer surface of the hood 51. The gap forms a drain channel 93. To form such a drain channel 93, for example, a support member 96 may be used as shown in the figure.

The tip end of the pick-off plate 91 is curved downward, and a gap is formed between the pick-off plate 91 and the upper end of the plate-like member 92. The pick-off plate 91 attached to the middle of the hood 51 has a through hole 95 having a small opening area. In addition, 94 is a partition member. As the steam dryer unit, a conventional one shown in FIG. 16 is used.

In the conventional steam dryer, when the steam flow rate is increased, the droplets s flow out of the corrugated plate portion 55 as shown in FIG. The wetness at the outlet Y of the flow path
At least one order of magnitude lower than the wetness at exit X. However, as shown in FIG. 13, most of the droplet s flowing out of the corrugated plate portion 55 collides with and adheres to the outer surface of the hood 51, but does not fall due to a high steam flow rate, and falls on the hood 51. It is conveyed and scatters as droplets from the upper end of the hood 51. This is a factor that increases the moisture at the flow path outlet Y of the steam dryer 50.

In the present embodiment, since the pick-off plate 91 and the plate member 92 are provided as described above, the droplet s from the corrugated plate portion 55 collides with the plate member 92 and becomes Adheres to Then, the droplets adhered on the surface of the plate member 92 rise by the steam flow, and jump into the drain channel 93 from the gap between the pickoff plate 91 and the tip of the plate member 92. At this time, since the tip of the pick-off plate 91 is curved downward, the liquid droplet rising on the plate member 92 can be captured by the pick-off plate 91 and surely jumped into the drain channel 93. it can.

The droplets that have jumped into the drain channel 93 fall down the drain channel 93 and fall into the drain gutter 75. Here, the steam flow that has exited the corrugated plate portion 55 is
Due to the pressure gradient generated in 3, the pressure rises in the drain channel 93. In order to cause the droplet to fall on the upward flow, it is necessary to reduce the speed of the upward flow. In the present embodiment, a through-hole 95 having a small opening area is formed in a pick-off plate 91 attached to an intermediate portion of the hood 51. Therefore, the upward flow of steam in the drain channel 93 is suppressed, and the drain channel 93
The droplet can be easily lowered in the inside.

In the present embodiment, the drain channel 93
Are provided in two stages above and below, but the droplet capture rate is improved in one stage or in multiple stages. Further, in the present embodiment, the steam dryer unit is that shown in FIG. 16, but it is also possible to install the steam dryer unit of any of the above-described first to fourth embodiments. By doing so, the droplet capture rate of the steam dryer is further improved.

[0045]

As described above, according to the present invention,
Since the droplet capturing function of the entire steam dryer is improved and the droplets contained in the steam can be efficiently removed, it is possible to sufficiently cope with an increase in the thermal output of the reactor core.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a steam dryer according to Embodiment 1 of the present invention.

FIG. 2 is a sectional view taken along line BB of FIG.

FIG. 3 is an explanatory diagram of droplet capture by an entrance porous plate.

FIG. 4 is an explanatory diagram of droplet capture by a corrugated plate portion.

FIG. 5 is an explanatory diagram of droplet capture by a steam dryer unit.

FIG. 6 is a comparison diagram of droplet capture performance.

FIG. 7 is a longitudinal sectional view of a steam dryer according to a second embodiment of the present invention.

FIG. 8 is a sectional view taken along the line CC of FIG. 7;

FIG. 9 is a longitudinal sectional view of a steam dryer according to Embodiment 3 of the present invention.

FIG. 10 is a longitudinal sectional view of a steam dryer according to a fourth embodiment of the present invention.

FIG. 11 is a longitudinal sectional view of a steam dryer according to a fifth embodiment of the present invention.

FIG. 12 is a sectional view taken along the line DD in FIG. 11;

FIG. 13 is an explanatory diagram showing the behavior of the droplet on the outer surface of the hood.

FIG. 14 is an explanatory diagram showing a behavior of a droplet on an outer surface of a hood according to a fourth embodiment.

FIG. 15 is a longitudinal sectional view of the improved boiling water reactor.

FIG. 16 is a longitudinal sectional view of a steam dryer according to the related art.

FIG. 17 is a sectional view taken along line AA of FIG. 16;

[Explanation of symbols]

 Reference Signs List 50 steam dryer 51 hood 52 inlet channel 53 outlet channel 55 corrugated plate 71 inlet perforated plate 73 outlet perforated plate 75 drain gutter 76 drain tube 77 upstream corrugated plate 78 downstream corrugated plate 77A, 78A flow channel 77B , 78B Slit 77C, 78C Pocket 91 Pickoff plate 92 Plate member 93 Drain channel 95 Through hole 700 Steam dryer unit 710 Upstream steam dryer unit 720 Downstream steam dryer unit

Claims (9)

[Claims] 1. A droplet capturing section provided with a curved flow path for capturing droplets from vapor flowing in the flow path, and a plurality of through holes formed to rectify the vapor in the droplet capturing section. In a steam dryer having a perforated plate, the droplet capture unit is divided into an upstream side and a downstream side along the flow direction of steam, and the upstream side droplet capture unit and the downstream side droplet capture unit A steam dryer, wherein a steam dryer unit is provided in which one of the perforated plates is interposed, and an upstream droplet capturing unit, a downstream droplet capturing unit, and a perforated plate are integrated. 2. The steam dryer according to claim 1, wherein a length of the upstream droplet capturing section along a flow direction of the steam is equal to a length of the downstream droplet capturing section. And steam dryer. 3. The steam dryer according to claim 1, wherein a length of the upstream droplet capturing unit along a flow direction of the steam is longer than a length of the downstream droplet capturing unit. And steam dryer. 4. A droplet capturing section provided with a curved flow path for capturing droplets from vapor flowing in the flow path, and a plurality of through holes formed to rectify the vapor in the droplet capturing section. In the steam dryer including the perforated plate, the droplet capturing unit is divided into an upstream side and a downstream side along a flow direction of the steam, and an upstream steam dryer unit and a downstream steam each having a unit structure. A steam dryer, comprising a dryer unit, and one of the perforated plates attached to a steam outlet side of the upstream steam dryer unit. 5. A droplet capturing section provided with a curved flow path for capturing droplets from vapor flowing in the flow path, and a plurality of through holes formed to rectify the vapor in the droplet capturing section. In the steam dryer including the perforated plate, the droplet capturing unit is divided into an upstream side and a downstream side along a flow direction of the steam, and an upstream steam dryer unit and a downstream steam each having a unit structure. A steam dryer, comprising a dryer unit, and one of the perforated plates attached to a steam inlet side of the downstream steam dryer unit. 6. A droplet capturing section provided with a curved flow path and capturing droplets from vapor flowing in the flow path, and a plurality of through holes formed to rectify the vapor in the droplet capturing section. A set of droplet trapping units and a porosity, comprising: a perforated plate; and a hood for covering the droplet capturing unit and the perforated plate and guiding vapor to the droplet capturing unit and the perforated plate. When the plate is a single steam dryer unit, in a steam dryer in which a plurality of sets of the steam dryer units are provided, a plate-shaped member provided on the outer surface of the hood with a gap between the hood surface and the outer surface of the hood. Member, comprising a droplet capture plate provided above the plate member to capture droplets, and impinging steam from the adjacent steam dryer unit on the plate member,
A steam dryer characterized in that droplets in steam flowing along the plate-like member are captured by the droplet capture plate and guided into the gap. 7. The steam dryer according to claim 6, wherein the steam dryer unit according to claim 1 is provided as the steam dryer unit. 8. The steam dryer according to claim 6, wherein the upstream steam dryer unit and the downstream steam dryer unit according to claim 4 or 5 are provided as the steam dryer unit. And steam dryer. 9. A nuclear power plant provided with the steam dryer according to any one of claims 1 to 8.