JPH06289186A - Cooling sea water discharge device for nuclear power plant - Google Patents

Abstract

PURPOSE:To provide a syphon type drainage device which drains the warm sea water which is used for cooling in a power generation plant and discharged into the sea without generating bubbles and white darkening, and is free from the breaking of the syphon pumping-up state during drainage, as for a coastal nuclear power plant. CONSTITUTION:A discharge device is constituted so that the warm sea water which is heat-exchange-processed in the plant equipment of a coastal nuclear power plant is drainaged into the sea through a syphon tube 13 from a primary water pool 12 installed at the position higher than the sea level in a high tide, and an ejector device 15 for sucking the air in the top part in the syphon tube into a drain stream at the flow speed of the drain stream in the syphon tube is provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cooling seawater discharger for a nuclear power plant, and more particularly to warm seawater discharged from power plant equipment of a coastal nuclear power plant from a primary reservoir provided at a position higher than the sea level at high tide. The present invention relates to a cooling seawater discharge device for a nuclear power plant for discharging water into the sea through a siphon pipe.

[0002]

2. Description of the Related Art At a seaside nuclear power plant, seawater pumped from the sea is used as a cooling medium for a diesel generator of a power plant, a cooling system for primary auxiliary machinery, or a condenser for turbine steam. In most cases, seawater whose temperature has risen due to heat exchange for cooling is constantly discharged into the sea as warm wastewater. This water discharge amount can reach up to hundreds of tons / min depending on the capacity of the plant, and therefore various effects on the water discharge area must be taken into consideration.

For example, in a general seaside nuclear power plant,
As a water discharge facility to discharge the warm seawater used for cooling in the power plant into the sea, in order to temporarily store the warm seawater discharged from the plant before discharging the water, the normal water level difference at high tide and typhoon The reservoir is located at a height so that it will not be flooded by the waves of the time, the tsunami at the time of the earthquake, and so on.

Warm seawater flowing from the plant into the reservoir is
Although it is discharged to the sea surface in a waterfall shape over the dam of the reservoir, a large amount of warm seawater, which may reach several meters or more, continuously falls to the sea surface with a large head, so that it looks like a large waterfall. A large amount of air is entrained in the seawater to generate a large amount of bubbles on the surface of the sea, and a large amount of fine bubbles are dispersed in the seawater to make the seawater cloudy.

Bubbles on the sea surface and seawater in a cloudy state formed in this manner are essentially free of pollutants, are clean and harmless, and naturally disappear over time. Bubbles on the surface of the sea may adsorb scales and dust in the atmosphere while floating on the surface of the sea, and may appear apparently dirty.Because the cloudiness of seawater takes a relatively long time to resolve itself. However, there was also the problem of spreading the ocean surface over a wide area to muddy water when it spreads far offshore, which could lead to misunderstandings of marine pollution.

[0006]

As a measure for preventing the occurrence of bubbles and cloudiness on the surface of the discharged water, a siphon pipe is installed across the dam of the reservoir, and warm seawater inside the reservoir and seawater below the discharged sea surface are It was considered that the water was continuously discharged under the sea surface through the siphon pipe by communicating with the siphon pipe, but in this case, the gas contained in the discharged seawater was separated in the siphon pipe to the top of the siphon pipe. There is a problem that the water gradually stops, and when the communication of seawater in the siphon pipe is cut off by the stagnant gas during use, the water discharge is stopped. Therefore, in this case, the air bleeding operation inside the siphon tube must be performed regularly, and the disadvantage that extra maintenance work is necessary cannot be avoided.

[0007] The present invention is a siphon tube system which does not cause bubbles on the surface of the discharged water or makes the seawater cloudy even when there is a head drop from the reservoir to the sea surface, and does not require regular air bleeding maintenance work. The purpose of the present invention is to provide a warm seawater discharge device for a nuclear power plant.

[0008]

DISCLOSURE OF THE INVENTION According to the present invention, warm seawater cooled by plant equipment of a seaside nuclear power plant is discharged into the sea from a reservoir provided at a height higher than the sea level at high tide through a siphon pipe. In order to achieve the above-mentioned object, the water discharge device sucks the air at the top of the siphon pipe into the water discharge flow according to the flow velocity of the water discharge flow in the siphon pipe. Equipped with an ejector device.

[0009]

According to the present invention, the warm seawater primarily stored in the reservoir does not fall like a waterfall over the weir of the reservoir to the sea surface, but the contact with the outside air is minimized through the siphon pipe. Is released directly into the seawater below sea level. Therefore, the warm seawater and the sea surface do not collide with each other when discharging the water, and the entrainment of air into the seawater due to this collision is also avoided.

The ejector device can be arranged in the downward water discharge flow in the siphon pipe, and the structure of the ejector device itself is, for example, a trumpet pipe that faces the water discharge flow in the siphon pipe and takes in the same, and the trumpet pipe. It can be realized by a general double pipe structure consisting of an outer tube surrounding the vicinity of the outlet of, and in this case, a negative pressure region is formed between the outer tube and the high-speed flow coming out of the outlet of the trumpet tube, If this negative pressure region is communicated with the top of the siphon pipe by another communication pipe, the gas accumulated at the top of the siphon pipe will have a negative pressure region from the communication pipe due to the ejector effect of the high-speed discharge flow whose flow velocity is increased by the trumpet pipe. And is discharged to the downstream of the siphon pipe together with the high-speed water discharge flow flowing in the outer pipe toward the outlet on the downstream side. As a result, siphoning by the siphon can be maintained without performing regular air venting operation.

In the conventional water discharge system, the drop flow rate of the discharged water is autonomously adjusted by increasing or decreasing the thickness of the warm seawater that crosses the dam of the reservoir according to the increase or decrease in the amount of discharged water. In the water discharge system using pipes, it is desirable to consider the balance between the inflow amount of warm seawater from the plant to the reservoir and the water discharge amount passing through the siphon pipe.

That is, when the amount of water discharged through the siphon is excessively large compared to the amount of water flowing into the reservoir per unit time, the air level in the reservoir drops and air intrudes through the siphon pipe opening to pump up the siphon. There is a possibility that the situation will be broken. On the other hand, if the amount of water discharged through the siphon pipe is extremely small compared to the amount of water flowing into the reservoir, the water level in the reservoir may rise and warm seawater may frequently overflow from the dam. Therefore, if the volume of the reservoir is relatively small and the inflow of warm seawater from the plant to the reservoir fluctuates greatly due to the load condition of the power plant, etc. It is desirable to adjust the water volume so that the siphon pumping condition is maintained.

For example, in addition to the water discharge by the water discharge device of the present invention, water discharge by a dam structure similar to the conventional one may be supplementarily performed, and a constant amount of water discharge forming a main part is discharged through a siphon pipe. However, when excess water discharge exceeds that level, even if the excess water is discharged over the dam and dropped to the sea surface, the generation of bubbles and cloudiness due to it will be much smaller than in the case of total drop in the past.

Another possibility is to selectively use a plurality of siphon tubes in parallel in a number corresponding to the amount of water discharged. In this case, the siphon pipe that is not in use is closed by an on-off valve at its subsea outlet, and the inlet and outlet sides of the siphon pipe are kept in communication with seawater.The siphon pumping will be performed immediately when the on-off valve is opened next time. Allow resuming.

One method of adjusting the balance between the amount of water flowing into the reservoir and the amount of water discharged through the siphon tube is to install a flow rate adjusting valve such as a butterfly valve on the fall side of the siphon tube and adjust the flow rate according to the water level in the reservoir. This is a method of adjusting the opening of the valve.

To start water discharge from an empty inside of the siphon pipe, the siphon pipe is opened while the opening on the reservoir side is immersed in warm seawater in the reservoir, and the opening on the sea side is immersed in the sea. The internal air is sucked from the top of the pipe with a suction pump to reduce the pressure. This decompression operation raises the water level in the siphon pipe, and when it exceeds the highest point on the bottom surface of the siphon pipe, warm seawater begins to fall to the sea side in the siphon pipe.
Pumping of warm seawater from the reservoir by siphon is started. After that, if the suction pump is stopped and the communication with the outside air at the top of the siphon pipe is cut off, this pumping is continued.

When warm seawater in a reservoir is pumped by a siphon pipe, the gas mixed in the warm seawater flowing inside becomes bubbles and tries to gather and stay at the top of the siphon pipe. Since the area is in the suction state by the ejector device as long as the flow of water is present in the siphon pipe, even if air bubbles stay at the top of the siphon pipe, the region is immediately sucked by the ejector device and is discharged to the downstream side of the siphon pipe. To be leaked.
Therefore, even during continuous water discharge, a large amount of gas does not stay in the siphon pipe due to the suction action of the ejector device, and the pumped state by the siphon is maintained without being broken.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a schematic diagram showing the configuration of the main part of a warm seawater discharger for a nuclear power plant according to an embodiment of the present invention. Here, the reservoir 1 of the conventional hot water discharge facility for nuclear power plants
2 is used as it is, and the siphon pipe 13 is arranged across the dam 12E.

In FIG. 1, used warm seawater flows into a reservoir 12 from a discharge pipe 11 from a power plant (not shown), and the reservoir 12 has a water level at the outer sea level 23 at high tide and waves at typhoon. It has a dam 12E that constitutes an overflow edge at a height position where it is not flooded by a tsunami at the time of an earthquake. Warm seawater 22 flowing into the reservoir 12 from the discharge pipe 11
Is once retained in the reservoir and then discharged into the seawater 24 through the siphon pipe 13.

One opening of the siphon pipe 13 is arranged below the water surface in the reservoir 12 and higher than the outside sea surface, and the seawater 2 passes through the upper part of the dam 12E higher than this opening.
The other opening is placed at a position lower than the sea level during low tide in 4 and the warm seawater inside the reservoir 12 is discharged at a flow rate almost equivalent to the inflow from the discharge pipe 11 due to the head pressure difference between both openings. Discharge into the sea.

An air reservoir 13 is provided at the top of the siphon tube 13.
H is provided, and the opening / closing valve 14 is provided in this air reservoir 13H.
A vacuum pump (not shown) is connected via. This vacuum pump is for exhausting the inside of the siphon pipe 13 to fill the inside of the siphon pipe 13 with seawater, and to start the siphon suction action of the warm seawater 22 from the reservoir 12.

When the siphon pipe 13 is filled with seawater and the siphon suction action is started, the warm seawater 22 in the reservoir 12 is discharged into the seawater 24 through the siphon pipe 13. At this time, the reservoir 12 of the siphon pipe 13
When air enters the siphon tube 13 together with warm seawater through the opening on the side, or the gas dissolved in the warm seawater separates as bubbles in the siphon tube, the gas gradually accumulates in the air pool at the top of the siphon tube, If it is left as it is, the water level inside the siphon pipe will gradually drop and eventually the siphon suction state will be broken.

In order to prevent this, in this embodiment, the air reservoir 13H of the siphon pipe 13 is connected to the ejector device 15 by the suction pipe 15P, and the air accumulated in the air reservoir 13H is sucked into the discharge flow. It is discharged into the sea along with water discharge. As a result, the siphon siphoning state is continuously maintained, and the warm seawater 22 can be continuously discharged into the seawater 24.

The ejector device 15 includes a trumpet pipe 15N for taking in a water discharge flow, which is arranged in a downward water discharge flow in the siphon pipe 13 with its inlet opening facing upstream, and the trumpet pipe 15
It has a general double pipe structure composed of an outer pipe 15M surrounding the vicinity of the N outlet nozzle, and in this case, the trumpet pipe 1
A negative pressure space 15S is formed in the outer pipe 15M by the high-speed flow coming out of the 5N outlet nozzle.
An air reservoir 13H at the top of the siphon pipe is connected to S by the suction pipe 15P. As a result, the gas accumulated at the top of the siphon pipe is stored in the air pool 1 by the ejector effect of the high-speed discharge flow whose flow velocity is increased by the trumpet pipe 15N.
3H is sucked into the negative pressure space 15S through the suction pipe 15P, and is swept out into the sea downstream in the siphon pipe 13 together with the high-speed water discharge flow flowing in the outer pipe 15M toward the downstream side outlet. I will go.

Here, the siphon tube 13 is an air reservoir 13
Some air bubbles are generated in the seawater 24 because the air accumulated in H is swept into the sea as air bubbles, but the air bubbles thus generated disappear shortly after the size and amount of the air bubbles have risen to the sea surface. Dam 1
Compared with the conventional water discharge method in which the water is dropped from 2E as it is, the amount of bubbles generated on the sea surface is small, and there is no concern that the seawater becomes cloudy.

In the above embodiment, an example in which the water discharger of the present invention is most simply described has been described, but the water discharger using the siphon tube with an ejector according to the present invention can be modified in various other ways. It goes without saying that this includes a system in which siphon pipes are provided in parallel as described above, or a system in combination with a flow rate adjusting valve such as a butterfly valve.

[0027]

As described above, according to the present invention,
The warm seawater in the reservoir is discharged directly below the sea surface through a siphon pipe installed across the dam, so there is no drop collision between the discharge flow and the sea surface, and the entrainment of air into the seawater due to this collision. Don't get up Therefore, even when a large amount of warm seawater is continuously discharged from a high place, the amount of bubbles generated on the sea surface of the discharge sea area is small, and there is no concern that the sea water in the adjacent sea area becomes cloudy.

In this case, according to the present invention, since the reservoir of the warm seawater discharge facility in the conventional nuclear power plant can be used as it is, the number of newly added facilities can be reduced and it can be easily adopted in the existing power plant. The advantage is that the installation period can be shortened.

Further, according to the water discharge device of the present invention, even if the gas is retained in the air pool at the top of the siphon pipe in the siphon pumping state, the ejector device can suck and discharge the gas by the energy of the water discharge flow. As a result, there is no fear that the siphon pumping state will be broken during the continuous water discharge for a long time.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing the configuration of a warm seawater discharger for a nuclear power plant according to an embodiment of the present invention.

[Explanation of symbols]

 11 Discharge pipe 12 Reservoir 13 Siphon pipe 14 Open / close valve 15 Ejector device 22 Warm seawater 23 Sea level 24 Seawater 12E Dam 13H Air reservoir 15N Wrapper pipe 15P Suction pipe 15S Negative pressure space 15M Outer pipe

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Yoshihiko Usui 1-6-8-107 Kita Toyonaka-cho, Izumiotsu-shi, Osaka

Claims (1)

[Claims] 1. To discharge warm seawater discharged by heat exchange in plant equipment of a seaside nuclear power plant into the sea through a siphon pipe from a primary reservoir provided at a position higher than the sea level at high tide The water discharge device for a nuclear power plant, comprising: an ejector device for sucking the air at the top of the siphon pipe into the discharge flow according to the flow velocity of the discharge flow in the siphon pipe.