JPH0424312A - Device to prevent jellyfish from entering the water intake - Google Patents

Abstract

PURPOSE:To prevent a jelly fish from entering into a water intake port by stretching a net so as to surround a curtain wall provided on the intake water inflow side of the water intake port, and by setting the stretching angle of the net to a value which is greater than a predetermined angle, with respect to the water bottom. CONSTITUTION:A curtain wall 3 is laid surrounding around the intake water inflow side of a water intake port 1 with a space between the curtain wall 3 and the water bottom 2. Outside of the curtain wall 3, a net 4 for preventing suspended matter from entering is stretched by means of a cable 5 or the like, surrounding the curtain wall 3. Further, the upper end of the cable 5 is locked to the curtain wall 3 while the lower end thereof is locked by a sinker block 6. Meanwhile, the net 4 is inclined by an angle more than an angle of 45 deg. with respect to the water bottom so as to be directed outward and downward from the curtain wall 3. With this arrangement, air bubbles jetted from an outside air jetting pipe 8 climbs up so as to sweep out the net 4, thereby it is possible to prevent jelly fishes floating around the net 4 from sticking to the net 4.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a device for preventing jellyfish from flowing into water intakes of thermal power plants, chemical factories, etc.

[Conventional technology] In thermal power plants, chemical factories, etc., large amounts of seawater are taken from sea areas and canals and used for cooling water, but if a large number of crabs occur, a large number of crabs will enter the water intake. This can lead to a situation where the output of the equipment that uses the cooling water decreases or the equipment has no choice but to shut down. For this reason, various measures have been taken to prevent this situation from occurring.

For example, in Jitsuma Heisei 1-176131,
A device is disclosed which is equipped with a net and water or air jetting means, and which makes a difference in preventing clubs from entering.

As shown in Fig. 9 fat and fbl, this device has a net 20 installed in front of the water intake 1, and a gap is provided between the lower part of the net 30 and the water intake 1, so that the effective water intake cross section is It is formed. Further, an air supply pipe 31 is disposed at the lower front of the net 30, and air is ejected from an air outlet 32 provided in the air supply pipe 31.

The air to be blown out is supplied from an air compressor 33 installed on land.

In the device with the above configuration, when air is ejected from the air outlet 32, rising water 7X (hereinafter referred to as an upward flow) is formed. 34 indicates air bubbles. The club riding on this upward flow is pushed up toward the water surface, and then leaves on the lateral flow that forms near the water surface.Therefore, the water intake passes under the net 30. The number of clubs flowing into mouth 1 decreases.

[Problems to be Solved by the Invention] However, in the conventional device described above, a large number of clubs often slip through the net and flow into the water intake. In other words, prevention of clubs from flowing in can be achieved by appropriately setting the arrangement of air supply pipes, the tensioning conditions of the net, etc.; simply installing nets or air supply pipes will not be effective. cannot be raised.

By the way, when air is ejected underwater, air bubbles rise and an upward flow of water is formed. The club rides this upward flow and rises, but as it rises, the club gradually moves laterally, and part of it attaches to the net. If water intake continues, the net will gradually become clogged. When the net is clogged, the water flow near the clogged part of the net becomes uneven, and the amount of water that flows from below the net to the water intake without passing through the net increases, and the water flow becomes faster. The club is then drawn into the accelerated downward flow and flows into the water intake.

In this way, by attaching the club to the net,
This will cause clubs to flow into the water intake, so an important point to prevent clubs from flowing into the water intake is to prevent clubs from attaching to the net. Regarding this point, in the conventional device described above, no consideration is given to preventing the club from adhering to the net.

SUMMARY OF THE INVENTION An object of the present invention is to provide a device that can prevent clubs from flowing into a water intake port without causing the clubs to adhere to the net.

[Means and effects for solving the problem] In order to achieve the above object, the present invention provides a curtain wall installed on the water intake inflow side of a water intake with a gap between the curtain wall and the water bottom. A net is placed on the outside of the curtain wall so as to surround the curtain wall and is slanted toward the outside of the curtain wall and placed at a distance from the bottom of the water. In the inflow prevention device for a club having an outer air jetting pipe arranged at a height lower than the lower edge, the net is set at an angle of 45° or more with respect to the bottom of the water.

In addition to the above configuration, it is even better to arrange an inner air jet pipe in the section between the force tension wall and the lower edge of the net in the planar arrangement. It is desirable to satisfy one or both of the following.

Arrange the outer air ejection pipe at a location where the lower edge of the net is at a position of 45° or more when viewed from the outer air ejection pipe.

The net is stretched so that the height from the bottom of the water to the lower edge of the net is lower than the height from the bottom of the water to the bottom edge of the curtain wall.

The present invention aims to prevent clubs from flowing into the net by preventing them from adhering to the net, and the effect of preventing clubs from adhering to the net will be explained with reference to conceptual diagrams of FIGS. 4 to 6.

In a device as shown in FIG. 4, in which a net 4 is stretched on the outside of a curtain wall 3 and an outside air jet pipe 8 is provided below the net, when air is jetted from the outside air jet pipe 8, the air rises. A flow AI is formed. Although the velocity of this upward flow A is large up to the height of the outer air jet pipe 8,
It becomes smaller towards the top. On the other hand, the intake water flow near the net 4 (flow toward the curtain wall 3) is because the intake water flows below the curtain wall 3.
The flow is fast near the bottom of the net 4, but it is extremely slow near the top of the net 4, or there is almost no flow.

When the water flow is in the above state, when the club 20 is raised on the upward flow AI, the net 4 where the water intake flow is fast
Near the bottom of , the rising speed of the upward flow A is large, so
The club 20 rises without attaching to the net 4. Furthermore, when the club 20 rises to the height of the top of the net 4, the rising speed of the upward flow A1 decreases, but the intake water flow also almost disappears, so the club 2° rises further and the net 4
and near the water surface, the upward flow A
1 changes into a horizontal flow B1, but the flow toward the water intake is blocked and weakened by the curtain wall 3, making it difficult for the club 2o to adhere to the net 4 near the water surface.

As shown in FIG. 5, in a device in which an inner air ejection pipe 9 is disposed between the curtain wall 3 and the net 4, air is ejected from the outer air ejection pipe 8 and the inner air ejection pipe 9. An upward flow A1 and an upward flow A2 are formed. Upward current A] pushes up the floating club 2o.

In this process, if the club 20 moves laterally toward the net 4 side, there is a risk that it will stick to the net 4, but since the upward flow A2 is formed inside the net 4, the club 20
is deflected upward, making it more difficult for it to adhere to the net 4. In addition, although the upward flow A2 also changes to a lateral flow B2 near the water surface, the flow toward the curtain wall 3 (ll) is dammed, thereby further preventing the club 20 from adhering to the net 4 near the water surface.

In the device configured as described above, the efficiency of preventing jellyfish adhesion varies depending on the tension angle of the net 4. The air ejected from the outer air jet pipe 8 becomes bubbles 2) and rises while diffusing. At this time, it is desirable that the air bubbles 2) rise in a sweeping manner over the air outlet 4. When the air bubbles 2) rise, clubs floating near the net 4 are pushed up and no longer float near the net 4.

In order to maintain such a state, the tension angle θ1 of the net shown in FIG. 6 should be made as large as possible, preferably 45° or more.

Also, the position of the lower edge 7 of the stretched net and the outer air jet pipe 8
The relationship with the placement position also affects the efficiency of preventing jellyfish adhesion. Similarly to the above, in order to raise the ejected air bubbles 2) along the net 4 and push up the club floating near the net 4, the lower edge 7 of the net in view of the position of the outer air ejection pipe 8 must be The positioning angle θ2 should be as large as possible, preferably 45 degrees or more, and the height from the bottom 2 to the lower edge 7 of the net (the distance between the net and the bottom) is also effective in preventing jellyfish from landing. affect. Since the intake water flows below the curtain wall 3, the flow velocity is fast at a water depth below the vicinity of the lower end of the curtain wall 3, and the flow velocity is slow at a water depth above the vicinity of the lower end of the curtain wall 3. In order to prevent the club from being drawn into this water intake flow, the height h from the water bottom 2 to the lower edge 7 of the net must be at least lower than the height H from the water bottom 2 to the lower end of the curtain wall 3, and It is best to set it to H 172 or higher. If the lower edge 7 of the net is lower than 1/2 of the above height H, the effect of preventing clubs from flowing in will be improved, but if the opening area of the net 4 is reduced due to the attachment of marine animals and plants, The frequency of maintenance and inspection of the net 4 must be increased because the degree of drift in the intake water flow is large and undesirable.

[Example] Figure 1 fat and fbl show an example of the present invention,
The figure (a) is a plan view, and the fbl figure is a diagram showing the AA cross section of the la1 figure. Surrounding the water intake inflow side of water intake 1 and the water bottom 2
A curtain wall 3 is provided with an interval between them, and intake water flows into the water intake port 1 from three directions below the curtain wall 3. curtain wall 3
A net 4 for preventing floating objects from flowing in is stretched around the outside of the curtain wall 3. This net 4 is stretched by ropes 5, and the upper end of the ropes 5 is locked to the curtain wall 3, and the lower end is locked to the sinker block 6. The net is inclined outwardly and downwardly, and there is a gap between the lower edge 7 of the net and the water bottom 2 to form an effective water intake cross section. An outside air jet pipe 8 is disposed at a position 1 outside the lower edge 7 of the net and lower than the lower edge 7 of the net, and an inside air jet pipe 9 is provided near the lower end of the outside (net side) of the curtain wall 3. is installed. The structure of the outer air ejection pipe 8 and the inner air ejection pipe 9 is such that a large number of pores or a large number of air ejection nozzles are provided on the upper side thereof, and the air is made as fine as possible and ejected. The outer air jet pipe 8 and the inner air jet pipe 9 are each connected to a pipe 10.11, which is connected via a header pipe 12 to an air compressor 13 that supplies air.

In the above embodiment, each of the outer air ejection pipe 8 and the inner air ejection pipe 9 is shown as one pipe, but the number and shape of the pipes are appropriately selected depending on the air ejection amount and the like.

FIG. 2 is a conceptual diagram showing another embodiment of the present invention. In this figure, 2 shows the bottom of the water, 3 shows the curtain wall, 4 shows the net, 5 shows the cables, 7 shows the lower edge of the net, and 8 shows the outer air jet pipe. Since these components are the same as those in FIG. 1, their explanation will be omitted. In this embodiment,
An inner air jet pipe 9 is arranged at the bottom of the water near the middle between the curtain wall 3 and the lower edge 7 of the net.

FIG. 3 is a conceptual diagram showing still another embodiment of the present invention. In this figure, the same components as in Figure 2 are as follows:
The same reference numerals will be given and the explanation will be omitted. In this embodiment, two inner air jet pipes 9a and 9b are arranged. The inner air ejection pipe 9a is arranged near the outer lower end of the curtain wall 3, and the inner air ejection pipe 9b is arranged at the bottom of the water near the middle between the curtain wall 3 and the lower edge 7 of the net.

Next, experimental results regarding the apparatus of the present invention will be explained.

(Experimental Apparatus) The experiment was carried out by placing the jellyfish inflow prevention experimental apparatus f (scale ratio 1/10) in a tidal waterway apparatus at a water depth of 1.2 m. The outline of the experimental apparatus will be explained with reference to FIG. 6. The height h from the water bottom 2 to the lower edge 7 of the net is 0.2 m, the height H from the water bottom 2 to the lower end of the curtain wall 3 is 0.5 m,
The stretching angle θ of the net 4 and the angle θ2 at which the lower edge 7 of the net is positioned when viewed from the position of the outer air jet pipe 8 are variable. The net 4 is made of nylon and has a mesh size of 9 mm square. The outer air ejection pipe 8 and the inner air ejection pipe 9 are made of vinyl chloride resin with an inner diameter of 12.5 cm, and holes each having a diameter of 1 cm are provided at ten pitches on the upper side.

The shape of the six pseudo jellyfish used as the floating jellyfish is as shown in FIG. 7, and the diameter of the umbrella part 25 is assumed to be 25 cm. The pseudo jellyfish was made of synthetic resin material and its specific gravity was adjusted to approximately 1.0.

(Experiment method) With the water flow below the curtain wall set at a flow rate of 0.054 m/sec and a predetermined flow rate of air being blown out from the outer air jet pipe and the inner air jet pipe, a considerable number of pseudo jellyfish were collected from the upstream side. was released.

The air jet flow rate was 504/min per meter of air jet tube. Then, after a predetermined period of time had passed since the release, the state of the pseudo jellyfish was divided into the following three states and counted.

The experiment was repeated three times and the counts were averaged.

■ Things that are attached to the net ■ Things that are floating ■ Things that have flowed under the curtain wall (experimental results) As shown in Figure 8, the lower edge 7 of the net seen from the position of the outer air jet pipe 8 Fix the position of on the 50° line and set the net 4
The results of the experiment by raising the upper edge step by step and changing the netting angle are shown in Table 1. In the table, α is the adhesion rate of the pseudo jellyfish to the net, and β is the floating rate of the pseudo jellyfish. , γ are the inflow rates of pseudo jellyfish that have burrowed under the curtain wall, and each is expressed as a percentage of the number released.

In addition, this table shows the performance measurement results when using a net that has been cleaned each time. Performance when the situation changes, such as when the net is clogged, must be judged by comprehensively considering each measurement value. be.

This table shows the results when air is ejected from both the outer air ejection pipe 8 and the inner air ejection pipe 9, and the results when air is ejected only from the outer air ejection pipe 8.

Looking at the results excluding Example 1.6 in Table 1 (both the outer air jet pipe 8 and the inner air jet pipe 9 were used), the adhesion rate α of pseudo jellyfish was 1% or less in all cases. Very small, and there is no difference between the examples, but
The inflow rate γ becomes a better value as the net tension angle θ1 becomes larger, and in particular, at 75° or more, it becomes 6 to 7%, which is an extremely good value. Net tension angle θ
When 1 is 50°, the inflow rate γ is 3596, which is relatively large, but within a practically acceptable range.

Comparing the adhesion rate α and the inflow rate γ when only the outer air ejection pipe 8 is used and when both the outer air ejection pipe 8 and the inner air ejection pipe 9 are used, with other conditions being the same (Example 1 Comparison of Example 2 or Example 6 and Example 7), Example 2 is better than Example 1, and Example 7 is better than Example 6, indicating that the effect of the inner air jet pipe 9 is obtained. There is. In particular, the difference in adhesion rate α is large.

In addition, the position of the lower edge of the net as viewed from the position of the outer air jet pipe was set at 45 degrees, but when the net was stretched at an angle of 35 degrees and an experiment similar to the above was conducted, the adhesion rate of pseudo jellyfish to the net was α reached 65%, which was poor.

Table 1 Net angle θ1; Net tension angle ○: Air jet [Effects of the invention] The present invention relates to a curtain wall, a net stretched outside the curtain wall, and an air flow arranged below the outside of the net. In devices equipped with a jetting pipe, the net is stretched at an angle of 45 degrees or more, which causes air bubbles ejected from the outside of the net to sweep upwards over the net and float near the net. Since it pushes up the jellyfish, it becomes difficult for the jellyfish to stick to the net, effectively preventing the inflow of jellyfish.9 In addition to the above configuration, if an air jet pipe is also placed inside the net, -E A rising current is formed, making it more difficult for jellyfish to adhere to the net, and preventing jellyfish from flowing in. In addition, if the air jet tube is arranged so that the lower edge of the net is at a position of 45 degrees or more from the air jet tube outside the net, the air bubbles will sweep over the net and rise, preventing jellyfish from entering the net. This prevents further adhesion and effectively prevents the influx of jellyfish.

Furthermore, if the height of the lower edge of the net is lower than the height of the lower end of the curtain wall, the area where the intake water flow rate is high is divided by the net, thereby increasing the effect of preventing jellyfish from flowing into the net.

[Brief explanation of drawings]

FIG. 1 is a diagram showing one embodiment of the present invention, FIG. 2 is a diagram showing another embodiment of the present invention, FIG. 3 is a diagram showing still another embodiment of the present invention, and FIGS. Figure 6 is an explanatory diagram of the jellyfish adhesion prevention effect of the present invention, Figure 7 is a diagram showing the pseudo jellyfish used in the experiment, Figure 8 is a schematic diagram of the experimental equipment, and Figure 9 is a conventional jellyfish inflow prevention device. It is a diagram. 1...Water intake, 2...Bottom, 3...Curtain wall, 4.30...Net, 5...Cables, 6...Sinker block, 7...Lower edge of net, 8.--Outer air jet pipe, 9.9a, 9b...Inner air jet pipe, 10
．． 11... Piping, 13.33... Air compressor, 20...
Jellyfish, 2). 34 - Bubbles.

Claims (4)

[Claims] (1) A curtain wall installed on the water intake inflow side of the water intake with a gap between it and the bottom of the water, and a curtain wall that surrounds the curtain wall and slopes downward to the outside of the curtain wall. A net stretched with a gap between it and the bottom of the water, and an outer air jet pipe located outside the lower edge of the net and at a lower height than the lower edge of the net. A device for preventing jellyfish from flowing into a water intake, characterized in that the net is stretched at an angle of 45° or more with respect to the bottom of the water. (2) The jellyfish inflow prevention device according to claim 1, wherein the inner air jet pipe is disposed in a section between the curtain wall and the lower edge of the net in a planar arrangement. (3) In the jellyfish inflow prevention device according to claim 1 or 2,
A device for preventing jellyfish from flowing into a water intake port, in which the outer air ejection pipe is arranged at a location where the lower edge of the net is at a position of 45 degrees or more when viewed from the outer air ejection pipe. (4) In the jellyfish inflow prevention device according to claim 1, 2 or 3, the net is stretched over the water intake so that the height from the bottom of the water to the lower edge of the net is lower than the height from the bottom of the water to the lower end of the curtain wall. A device to prevent jellyfish from entering.