JP2001004787A - Structure of water discharge pit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a structure of water discharge pit capable of compacting the water discharge pit and reducing construction cost. SOLUTION: The structure of water discharge pit for discharging from the bottom layer without bubbles by reducing bubble generated by air entrainment, dispersing falling water stream with a perforated plate and shallowing the penetration depth of bubble into the water tank is characterized by constituting of the perforated plate 6 and a sill 10 placed on the upper surface of the perforated plate 6 for weakening water force.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to the structure of a water discharge pit.

[0002]

2. Description of the Related Art In a thermal power plant and a nuclear power plant, foams generated in a spillway system may be discharged into the sea area to damage the landscape.
If foaming occurs after the start of operation of the power plant, a large amount of cost is required for countermeasures. Therefore, it is desired to design a water discharge channel without foaming. The basic measure for preventing foaming of bubbles generated by air entrainment is a method that does not create a water flow that falls by overflowing a weir, which is a typical foaming cause, that is, a so-called waterfall drop. However, when the damping method is unavoidable, the following method is used as a foam prevention measure.

<A> Prevention of air entrainment In order to operate the water level of the water discharge tank within a certain range, a valve adjustment discharge type in which the valve opening is adjusted by the flow rate. A siphon discharge type in which one on / off of the valve adjustment discharge is replaced by a siphon. A water flow cover that covers the waterfall drop area with a strong sheet or steel floating body to prevent air entrainment.

<B> Bubble treatment A pipe discharge type with an air pipe that floats bubbles in a pressure channel and exhausts the air from an air pipe. Curtain wall and shower type that prevent foam from flowing out at the end of the waterway or the curtain wall at the front and defoam in the shower. Dispersion falling bottom layer discharge type, in which falling water veins are dispersed by a grid etc. to reduce the depth of penetration of bubbles into the water tank and discharge from the bottom layer without bubbles. Suction hot air treatment type that sucks floating bubbles and separates air.

However, among the above-mentioned various methods, in the case of the dispersed falling bottom layer discharge method, since it is necessary to discharge the water from a deep place where there is no bubble in consideration of the depth of penetration of the bubble, it is necessary to enlarge the water discharge pit, and the construction cost is increased. Is increased.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide a structure of a water discharge pit which can reduce the construction cost by reducing the size of the water discharge pit in order to solve the above problems.

[0007]

Means for Solving the Problems In the first invention, in order to reduce bubbles generated by air entrainment, falling water veins are dispersed by a perforated plate to reduce the depth of penetration of bubbles into the water tank, and to reduce A water discharge pit for discharging water from the bottom layer,
This is a structure of a water discharge pit, which is constituted by a sill installed on an upper surface of a perforated plate to reduce a water force. The second invention is a water discharge pit for dispersing falling water veins with a perforated plate so as to reduce the depth of penetration of bubbles into the water tank and to discharge the bubbles from the bottom layer without bubbles in order to reduce bubbles generated by air entrainment. The drainage pit is characterized in that an upwardly-directed swash plate is installed on the upper surface of the perforated plate toward the upstream, and the leading end of the swash plate is located below the surface of the water flow. Structure. The third invention is a water discharge pit for dispersing falling water veins with a perforated plate to reduce bubbles generated by air entrainment, to reduce the depth of penetration of bubbles into the water tank, and to discharge water from a bubble-free bottom layer. Wherein the top surface is horizontal and the bottom surface is provided with an inclined surface perforated plate forming an upwardly inclined surface toward the downstream, and an air vent pit at a downstream end of the inclined surface perforated plate. Pit structure. According to a fourth invention, in the structure of the water discharge pit according to any one of the first invention to the third invention, the perforated plate has a multilayer structure, and the diameter of the hole of the upper perforated plate is changed to the diameter of the lower perforated plate. The structure of the water discharge pit, which is larger than the diameter of the hole.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

<A> Overall Configuration FIG. 1 is a side sectional view showing the structure of a water discharge pit according to the present invention, and FIG. 2 is a plan view thereof. Wastewater W discharged from the thermal and nuclear power plants into the sea area is discharged from the discharge pipe 1 to the upstream water tank 2, overflows the weir 3, becomes a falling water vein, and is discharged to the downstream water tank 4. The downstream water tank 4 includes a wall 5 having an open bottom, and a perforated plate 6 installed on the entire surface of the wall 5 and the weir 3. Partition wall 7 depending on the size of downstream water tank 4
And the opening 8 may be provided.

<B> Perforated Plate The perforated plate 6 is, for example, a plate-like body, and has a plurality of holes 9 penetrating therethrough. On the upper surface of the perforated plate 6, a sill 10 serving as an obstacle for weakening the momentum of the water flow of the falling water vein is installed. The height of the perforated plate 6 is set so that the upper surface of the perforated plate 6 coincides with the top of the weir 3 so that the installation height of the perforated plate 6 is lower than the water surface of the drainage W discharged from the upstream water tank 2 to the downstream water tank 4. I do. By installing the perforated plate 6, the weir 3 overflows and becomes a falling water vein to disperse the water force of the drainage W discharged to the downstream water tank 4, so that the penetration depth of the bubbles 11 generated by air entrainment is reduced, and from the bottom layer Drainage W without bubbles 11 can be discharged.

<C> Sill A sill 10 is provided on the upper surface of the perforated plate 6. Sill 10
Is installed, for example, at the center of the perforated plate 6 so as to block the water force in the transverse direction of the water flow of the drainage W. Due to the installation of the sill 10, the flow rate passing from the hole 9a on the upstream side of the perforated plate 6 to the downstream water tank 4 increases, and conversely, the flow rate passing from the hole 9b on the downstream side of the perforated plate 6 to the downstream water tank 4 decreases. Become. (Arrow) By this flow control action, the penetration depth of the bubbles 11 near the wall 5 generated by the entrainment of air can be reduced, and the drainage W without bubbles 11 can be discharged from the bottom layer of the downstream water tank 4.

[0012]

The operation of the present invention will be described below.

<B> Drainage to upstream water tank Drainage W released to sea area from thermal power and nuclear power plants
Is discharged from the discharge pipe 1 to the upstream water tank 2. Upstream water tank 2
Is discharged to the downstream water tank 4 after overflowing the weir 3 and forming a falling water vein. The drainage W that has become the falling water vein becomes a wedge-shaped water vein (nap) and falls into the downstream water tank 4 at a large downward flow velocity.

<B> Drainage into the Downstream Water Tank The wastewater W that has overflowed the weir 3 and has become a falling water vein falls into the perforated plate 6 installed on the upper surface of the downstream water tank 4, and
Is dispersed (reduced). By the sill 10 installed on the upper surface of the perforated plate 6 and installed in the transverse direction of the water flow, the perforated plate 6
The flow rate of the water flow passing through is uneven to the upstream side of the perforated plate 6. Drainage W passing from the upstream side hole 9a of the perforated plate 6 to the downstream water tank 4
, And conversely, the flow rate of the drainage W passing from the hole 9b on the downstream side of the perforated plate 6 to the downstream water tank 4 decreases. (Arrow) Bubbles 1 generated due to entrainment of air by this flow control action
1, the penetration depth can be adjusted. That is, the penetration depth of the foam 11 is deep on the upstream side of the downstream water tank 4 having a large flow rate,
On the downstream side of the downstream water tank 4 having a small flow rate, the penetration depth of the foam 11 is shallow.

<C> Discharge outside the water tank The drainage W in the downstream water tank 4 is discharged from the bottom of the bottom open wall 5 to the outside of the water tank. Since the depth of the drainage W is controlled in the downstream water tank 4 by the penetration depth of the foam 11, the wall 5 is discharged to the outside.
There is no bubble 11 in the vicinity of the lower part, and there is no fear that the bubble 11 is discharged out of the water tank together with the drainage W.

[0016]

Second Embodiment FIG. 3 is a side sectional view showing another embodiment, and FIG. 4 is a plan view thereof. In the present embodiment, on the upper surface of the perforated plate 6, a water guide swash plate 12 having an upward slope is installed toward the upstream, and the leading end of the water guide swash plate 12 is installed so as to be located below the surface of the water flow. .

The inclination angle of the swash plate 12 is set so as to be parallel to the flowing water surface shape without the swash plate 12. After the swash plate 12 is installed, the drainage W also flows on the swash plate 12. Let it flow. The drainage W flowing on the lower surface of the water guide swash plate 12 flows from the upstream hole 9 a of the perforated plate 6, and the drainage W flowing on the upper surface of the water guide swash plate 12 flows from the downstream hole 9 b of the perforated plate 6 into the downstream water tank 4. So that it flows to

The height of the upper surface of the perforated plate 6 is set so as to coincide with the top end of the weir 3 of the downstream water tank 4. The installation height of the lower surface of the perforated plate 6 is set to be lower than the low water level. This is a swash plate 1
This is because the drainage W that has flowed down the lower surface of the nozzle 2 flows into a pressure channel.

With the installation of the water guide swash plate 12, the waste water W passing from the hole 9a on the upstream side of the perforated plate 6 to the downstream water tank 4 falls into the downstream water tank 4 without touching the air. There is no. The drainage W passing from the hole 9b on the downstream side of the perforated plate 6 to the downstream water tank 4 comes into contact with the air and falls into the downstream water tank 4, so that bubbles are generated by entrained air. However, the flow rate contributing to the generation of bubbles is smaller than when there is no swash plate 12. By the action, the generation amount of the bubbles 11 can be reduced, and the drainage W without the bubbles 11 can be discharged to the outside. (Arrow)

[0020]

Third Embodiment FIG. 5 is a side sectional view showing still another embodiment, and FIG. 6 is a plan view thereof. The perforated plate in the present embodiment has an inclined surface perforated plate 13 whose upper surface is horizontal and whose bottom surface forms an upwardly inclined surface facing downstream, and an air vent pit 15 at the downstream end of the inclined surface perforated plate 13. Is formed.

When the perforated plate is installed, bubbles 11 are generated on the lower surface thereof. The generated bubbles 11 pass through the holes 9 of the perforated plate, but the drainage W flows from the upstream, so that the efficiency of air release is poor. Conversely, due to the drainage W flowing from the upstream,
The bubbles 11 are not easily removed again when the water is carried deep into the water.

For this reason, a gap is provided between the rising wall 14 at the end of the sloped perforated plate 13 and the wall 5 of the downstream water tank 4, and this gap becomes an air vent pit 15, and the air bubbles 11 (air) floating in the downstream water tank 4 are formed. ). Since the bottom surface of the sloped perforated plate 13 forms an upward slope toward the downstream, the bubbles 11 can easily move to the air vent pit 15.
Because the underwater bubbles 11 have the property of floating vertically upward,
It moves to the vicinity of the air vent pit 15 along the upper side of the inclined surface and floats. The floating bubbles 11 are drawn out by the air vent pits 15. Therefore, the drainage W with few bubbles 11 can be discharged to the outside.

[0023]

Embodiment 4 FIG. 7 is a perspective view showing another embodiment of a perforated plate. The perforated plate in the present embodiment is a multilayer perforated plate 16 having a double structure of a first perforated plate 16a and a second perforated plate 16b. First perforated plate 16a arranged on the upper surface
The diameter of the hole 9 is larger than the diameter of the hole 9 of the second perforated plate 16b disposed on the lower surface. 1, 3 and 5, the falling water vein overflowing the weir 3 is first dispersed in the water force by the first perforated plate 16 a, and
Since the water force is further dispersed by the small holes 9 of 6b,
It has a function of reducing the depth of the foam 11 penetrating into the downstream water tank 4. Due to the dispersion of the water force, the flow rate of the drainage W per one of the holes 9 passing through the downstream water tank 4 decreases. By this flow rate control action, the penetration depth of the bubbles 11 generated due to the entrainment of air can be adjusted, and the drainage W without the bubbles 11 can be discharged to the outside.

[0024]

Since the present invention has been described above,
The following effects can be obtained. <A> Since the amount of bubbles that penetrate near the discharge port is small, the amount of bubbles that flow out is small. <B> The depth of penetration of the foam can be reduced by adjusting the flow rate,
Therefore, the water tank can be small, and the construction cost can be reduced. <C> Since the drainage flowing under the swash plate flows in the pressure channel, it does not come into contact with air and does not generate bubbles. <D> Although the drainage flowing on the swash plate flows through the open channel, bubbles are generated. However, compared to the case without the swash plate, the flow rate causing the bubbles is small, and thus the generation of bubbles is small. <E> Since the bottom surface of the perforated plate forms an upwardly inclined surface toward the downstream, the bubbles can easily move to the air vent pit. <F> Since the foam that has moved along the bottom surface of the perforated plate is vented by the air vent pit, the amount of the foam flowing downstream is reduced.

[Brief description of the drawings]

FIG. 1 is a side sectional view showing the structure of a water discharge pit according to the present invention.

FIG. 2 is a plan view of the same.

FIG. 3 is a side sectional view showing another embodiment.

FIG. 4 is a plan view of the same.

FIG. 5 is a side sectional view showing still another embodiment.

FIG. 6 is a plan view of the same.

FIG. 7 is a perspective view showing another embodiment of a perforated plate.

Claims (4)

[Claims] 1. A water discharge pit for dispersing falling water veins with a perforated plate to reduce the depth of penetration of bubbles into a water tank and to discharge bubbles from a bubble-free bottom layer in order to reduce bubbles generated by air entrainment. The structure of the water discharge pit, comprising a perforated plate and a sill installed on the upper surface of the perforated plate to reduce the water force. 2. In order to reduce bubbles generated by air entrainment, a falling water vein is dispersed by a perforated plate to reduce the depth of penetration of bubbles into a water tank, and to be discharged from a bubble-free bottom layer at a water discharge pit. The water discharge pit is characterized in that a swash plate with an upward slope is installed on the upper surface of the perforated plate toward the upstream, and the tip of the swash plate is located below the surface of the water flow. Construction. 3. A water discharge pit for dispersing falling water veins with a perforated plate so as to reduce the depth of penetration of bubbles into the water tank and discharge the bubbles from a bubble-free bottom layer in order to reduce bubbles generated by air entrainment. Water discharge, characterized in that the upper surface is horizontal and the bottom surface is provided with a sloped perforated plate forming an upwardly inclined surface facing downstream, and an air vent pit at a downstream end of the sloped perforated plate. Pit structure. 4. The structure of the water discharge pit according to claim 1, wherein the perforated plate has a multilayer structure, and the diameter of the hole of the upper perforated plate is changed to the diameter of the hole of the lower perforated plate. The structure of the water discharge pit, characterized by being larger.