JP2502788B2 - Jellyfish inflow prevention device to the intake - Google Patents

Description

TECHNICAL FIELD The present invention relates to a device for preventing jellyfish from flowing into an intake port of a thermal power plant, a chemical factory, or the like.

[Prior Art] In thermal power plants, chemical plants, etc., a large amount of seawater is taken from sea areas and canals and used as cooling water. However, when a large number of jellyfish occurs, a large number of jellyfish enter the intake. As a result, the output of the device that uses the cooling water decreases, and sometimes the device must be stopped. Therefore, various measures have been conventionally taken to prevent such a situation.

For example, Japanese Utility Model Laid-Open No. 1-176131 discloses a device that includes a net and water or air jetting means to prevent the inflow of jellyfish. This device is shown in FIG.
As shown in (b), a net 20 is installed in front of the water intake 1, and a space is provided between the lower portion of the net 30 and the water intake 1 to form an effective water intake cross section. Further, an air supply pipe 31 is arranged in front of the lower portion of the net 30,
Air is ejected from an air ejection port 32 provided in the air supply pipe 31. The air to be jetted is supplied from an air compressor 33 installed on land.

In the apparatus having the above structure, when air is ejected from the air ejection port 32, a rising water flow (hereinafter, referred to as an upflow) is formed. 34 indicates a bubble. For this reason, it is said that the jellyfish floating near the seabed are pushed up in the direction of the water surface by riding on this upward flow, and then they are moved out by riding in the lateral flow formed near the water surface. Therefore, the number of jellyfish flowing under the net 30 and flowing into the intake port 1 is reduced.

[Problems to be Solved by the Invention] However, in the above-mentioned conventional device, a large amount of jellyfish often dive under the net and flow into the water intake port. In other words, the prevention of jellyfish inflow is achieved by appropriately setting the arrangement of the air supply pipes, the tension conditions of the net, etc., and simply installing the net or the air supply pipe improves the effect. It is not possible.

By the way, when air is ejected in water, an ascending flow of water is formed together with the rise of air bubbles. The jellyfish climb on this upward flow, but the rising jellyfish gradually moves laterally, and some of them attach to the net. If the water intake is continued, the net will gradually become clogged. When the net is clogged, the water flow in the vicinity of the clogged part of the net becomes uneven, and the amount of water flowing from the lower part of the net to the intake port without passing through the net increases, and the water flow becomes faster. Then, the jellyfish are drawn into the accelerated flow below the net and flow into the intake.

As described above, the jellyfish attach to the net, which causes the jellyfish to flow into the intake port. Therefore, an important point for preventing the jellyfish from flowing is to prevent the jellyfish from attaching to the net. Regarding this point, in the above-mentioned conventional device, no consideration is given to prevent the jellyfish from adhering to the net.

An object of the present invention is to provide a device that can prevent jellyfish from flowing into the intake port without adhering to the net.

[Means and Actions for Solving the Problems] In order to achieve the above-mentioned object, the present invention provides a curtain wall provided at an intake inflow side of an intake port with a space provided between the curtain wall and the curtain wall. A net that is extended from the vicinity of the upper end of the curtain wall toward the outside and downward of the curtain wall so as to surround the net, and has a space between the lower edge and the water bottom. In a jellyfish inflow prevention device, which is located outside and has an outer air ejection pipe arranged at a height lower than the lower edge of the net, the net tension angle is set to 50 ° or more with respect to the water bottom. There is.

In addition to the above configuration, the inner air ejection pipe is arranged in the section between the curtain wall and the lower edge of the net in the plane arrangement.

In each of the above inventions, it is desirable to satisfy one or two of the following conditions.

The angle of the lower edge of the net seen from the outer air ejection pipe is
Be at least 50 ° to the bottom of the water.

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

The present invention is intended to prevent the inflow of jellyfish by preventing them from adhering to the net, and the jellyfish adhesion preventing action will be described with reference to the conceptual diagrams of FIGS. 4 to 6.

As shown in FIG. 4, in the device in which the net 4 is stretched outside the curtain wall 3 and the outside air ejection pipe 8 is provided below the outside of the curtain wall 3, when air is ejected from the outside air ejection pipe 8, the net 4 rises. Stream A ₁ is formed. The velocity of the ascending flow A ₁ is large at a certain height from the outer air ejection pipe 8, but becomes smaller as it goes upward. On the other hand, the flow of water intake near the net 4 (flow toward the curtain wall 3)
Since the intake water flows under the curtain wall 3, it is fast near the lower part of the net 4, but extremely slow near the upper part of the net 4, or there is almost no such flow. When the jellyfish 20 is lifted on the ascending flow A _{1 under the} above water flow conditions, the ascending speed of the ascending flow A ₁ is high near the lower part of the net 4 where the water intake is fast.
Rises without attaching to the net 4. Also, when the jellyfish 20 has risen to the height of the upper part of the net 4, the ascending flow A ₁
However, the jellyfish 20 further rises and does not adhere to the net 4 because the flow rate of water intake is almost eliminated. Then, near the water surface, the upward flow A ₁ is the lateral flow B ₁
However, the flow toward the intake is curtain wall 3
The jellyfish 20 is less likely to adhere to the net 4 near the water surface because it is dammed and weakened by the water.

As shown in FIG. 5, in the device in which the inner air ejection pipe 9 is arranged between the curtain wall 3 and the net 4, by ejecting air from the outer air ejection pipe 8 and the inner air ejection pipe 9, Upflow A ₁ and upflow A ₂ are formed. Updraft A ₁ pushes up floating jellyfish 20. In this process, when the jellyfish 20 moves laterally toward the net 4, there is a risk that it will adhere to the net 4, but since the upward flow A ₂ is formed inside the net 4, the jellyfish 20 The direction of the net 4 is changed upward, and the attachment to the net 4 becomes more difficult to occur. The upward flow A ₂ also changes to a lateral flow B ₂ near the water surface, but the flow to the curtain wall 3 side is blocked, so that the jellyfish 20 is further prevented 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 outside air ejection pipe 8 rises while forming bubbles 21 while diffusing, and at this time, it is desirable that the bubbles 21 rise so as to sweep over the net 4. When the bubble 21 rises in such a state, the jellyfish floating in the vicinity of the net 4 is pushed up and does not float in the vicinity of the net 4. In order to maintain such a state, it is preferable that the tension angle θ ₁ of the net shown in FIG. 6 be as large as possible, and it is suitable that it is 50 ° or more.

Further, the relationship between the position of the stretched net lower edge 7 and the position of the outer air ejection pipe 8 also affects the efficiency of jellyfish adhesion prevention. Similar to the above, in order to raise the air bubbles 21 of the jetted air along the net 4 and push up the jellyfish floating in the vicinity of the net 4, the surface connecting the outer air jetting pipe 8 and the lower edge 7 of the net is The angle θ ₂ formed with the bottom of the water is preferably as large as possible, and is suitably 50 ° or more.

The height from the water bottom 2 to the lower edge 7 of the net (the distance between the net and the water bottom) also affects the efficiency of jellyfish prevention.
Since water intake flows under the curtain wall 3, the flow velocity is high at a water depth below the vicinity of the lower end of the curtain wall 3,
At a water depth above the vicinity of the lower end of the curtain wall 3, the flow velocity is slow. In order to prevent the jellyfish from being drawn into this intake flow, the height h from the water bottom 2 to the lower edge 7 of the net is at least lower than the height H from the water bottom 2 to the lower end of the curtain wall 3, and the above-mentioned height. It is better to make it half or more of H. When the lower edge 7 of the net is lower than 1/2 of the height H, the effect of preventing jellyfish inflow is improved, but when the opening area of the net 4 is reduced due to the attachment of marine flora and fauna, the net around 4 is removed. Since the degree of uneven flow in the water flow is large, which is not preferable, the frequency of maintenance and inspection of the net 4 must be increased.

[Example] FIG. 1 (a). (B) shows an embodiment of the present invention,
(A) figure is a top view, (b) figure is a figure which shows the AA cross section of (a) figure. Surrounds the intake inlet side of intake 1 and bottom 2
The curtain wall 3 is provided with a space between the curtain wall 3 and the water intake port, and the intake water flows into the intake port 1 from three directions below the curtain wall 3. Curtain wall 3
A net 4 for preventing the inflow of suspended matter is stretched on the outer side of the so as to surround the curtain wall 3. The net 4 is stretched by cords 5, the upper ends of the cords 5 are locked to the curtain wall 3, and the lower ends thereof are locked to the sinker blocks 6. The stretched net 4 is inclined downward toward the outside of the curtain wall 3, and an effective water intake cross section is formed between the lower edge 7 of the net and the water bottom 2 with a gap. An outer air jet pipe 8 is arranged outside the net lower edge 7 and at a position lower than the net lower edge 7, and an inner air jet pipe 9 is provided near the lower end (outer side of the net) of the curtain wall 3. It is arranged. The outer air ejecting pipe 8 and the inner air ejecting pipe 9 have a structure in which a large number of pores or a large number of air ejecting nozzles are provided on the upper side of the outer air ejecting pipe 8 and the inner air ejecting pipe 9. The outer air ejection pipe 8 and the inner air ejection pipe 9 are connected to pipes 10 and 11, respectively, and the pipes 10 and 11 are header pipes 12 respectively.
It is connected to an air compressor 13 which supplies air via.

In the above embodiment, the outer air ejection pipe 8 and the inner air ejection pipe 9 are each shown as one pipe. The number or shape of them is appropriately selected according to the air ejection amount.

FIG. 2 is a conceptual diagram showing another embodiment of the present invention. In this figure, 2 is a water bottom, 3 is a curtain wall, 4 is a net, 5 is cords, 7 is a lower edge of the net, and 8 is an outer air ejection pipe. Since these constituent parts are the same as those in FIG. 1, their explanations are omitted. In the present embodiment, the inner air ejection pipe 9 is arranged at the water bottom near the middle of the curtain wall 3 and the lower edge of the net 7.

FIG. 3 is a conceptual diagram showing still another embodiment of the present invention. In this figure, the same components as those in FIG. 2 are designated by the same reference numerals and the description thereof will be omitted. In this embodiment, two inner air ejection 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 water bottom near the middle between the curtain wall 3 and the net lower edge 7.

Next, the experimental results regarding the device of the present invention will be described.

(Experimental device) The experiment was carried out by arranging a jellyfish inflow prevention experimental device (scale ratio 1/10) in a tidal water channel device with a water depth of 1.2 m. The outline of the experimental apparatus will be described 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, and the net 4 is Zhang angle at which theta ₁ and the angle theta ₂ which the surface connecting the lower edge 7 of the outer air ejection tube 8 and the net with respect to the water bottom is respectively turned variable. The net 4 is made of nylon with 9 mm square mesh.
The outer air ejecting pipe 8 and the inner air ejecting pipe 9 are made of vinyl chloride resin having an inner diameter of 12.5 mm, and a hole with a diameter of 1 mm is 10 mm on the upper side.
It is provided on the pitch.

A pseudo jellyfish was used as the floating jellyfish. The shape of the pseudo jellyfish is as shown in FIG. 7, and it is assumed that the umbrella portion 25 has a diameter of 25 cm. The pseudo jellyfish was made of synthetic resin material and adjusted so that its specific gravity was about 1.0.

(Experimental method) With a water flow below the curtain wall set to a flow velocity of 0.054 m / sec, and with a predetermined flow rate of air being ejected from the outer air ejection pipe and the inner air ejection pipe, a considerable number of pseudo jellyfish was detected from the upstream side. It was released. Air ejection flow rate per 1m air ejection tube
It was set to 50 l / min. Then, after a predetermined time has passed since the release,
The state of the pseudo jellyfish was divided into the following three states and counted. The experiment was repeated 3 times and the counts were averaged.

Those attached to the net Floating things Flowing under the curtain wall (Experimental results) As shown in Fig. 8, the surface connecting the outer air jet pipe 8 and the lower edge 7 of the net is , The angle θ ₁ to the bottom of the water is 50 °
Table 1 shows the results of an experiment in which the upper edge of the net 4 was gradually raised to change the tension angle of the net.
In the table, α is the attachment rate of the pseudo-jellyfish to the net, β is the floating rate of the pseudo-jellyfish, and γ is the inflow rate of the pseudo-jellyfish that has dipped under the curtain wall, and each is shown as a percentage of the released number. In addition, this table shows the results of performance measurements when using a net that was cleaned each time, and it is necessary to judge the performance when the conditions such as clogging of the net change by comprehensively examining each measured value. is there.

Then, this table shows the result when air is ejected from both the outer air ejection pipe 8 and the inner air ejection pipe 9 and the result when air is ejected only from the outer air ejection pipe 8.

In Table 1, looking at the results excluding Examples 1 and 6 (using both the outer air ejection tube 8 and the inner air ejection tube 9), the attachment rate α of the pseudo jellyfish was 1% or less. It is extremely small, and there is no difference between the examples. But,
The inflow rate γ has a good value as the net tension angle θ ₁ increases, and is 6 to 7% at 75 ° or more, which is an extremely good value. Net tension angle θ ₁
The inflow rate γ at a value of 50 ° is 35%, which is relatively large, but is within the practically acceptable range.

The other conditions are the same, and the adhesion rate α and the inflow rate γ are compared between the case where only the outer air ejection pipe 8 is used and the case where both the outer air ejection pipe 8 and the inner air ejection pipe 9 are used (Example 1 And Example 2 or Example 6 and Example 7), Example 2 is better than Example 1, Example 7 is better than Example 6, and the effect of the inner air ejection pipe 9 is shown. There is. In particular, the difference in the adhesion rate α is large.

The angle of the bottom edge of the net seen from the outside air jet pipe was set to 50 ° with respect to the water bottom, but the net tension angle was set to 35 °.
Then, when an experiment similar to the above was carried out, the adhesion rate α of the pseudo jellyfish to the net reached 65%, which was unsatisfactory.

[Advantages of the Invention] The present invention is an apparatus including a curtain wall, a net stretched outside the curtain wall, and an air ejection pipe arranged below the outside of the net. The temperature is above 0 ° C. As a result, air bubbles ejected from the outside of the net rise as if sweeping over the net and push up the jellyfish floating in the vicinity of the net, making it difficult for the jellyfish to attach to the net, Inflow can be effectively prevented.

In addition to the above configuration, if an air jet pipe is arranged inside the net, an upward flow is formed on the outside and the inside of the net, and it becomes more difficult for the jellyfish to attach to the net, and the inflow of jellyfish can be prevented. Also, if the outer air ejection pipe is arranged so that the angle of the lower edge of the net seen from the outer air ejection pipe is 50 ° or more with respect to the water bottom, air bubbles will rise as if sweeping over the net. Will not adhere to the net anymore and can effectively prevent the inflow of jellyfish.

Furthermore, if the height of the lower edge of the net is set lower than the height of the lower end of the curtain wall, the range in which the flow speed of water intake is high is partitioned by the net, and the effect of preventing jellyfish inflow is improved.

[Brief description of drawings]

FIG. 1 is a diagram showing an 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. FIG. 6 is an explanatory view of the jellyfish adhesion preventing action of the present invention, FIG. 7 is a view showing a pseudo jellyfish used in an experiment, FIG. 8 is a schematic diagram of an experimental device, and FIG. 9 is a conventional jellyfish inflow preventing device. It is a figure. 1 ... Intake port, 2 ... Water bottom, 3 ... Curtain wall,
4,30 ... Net, 5 ... Cords, 6 ... Sinker block, 7 ... Lower edge of net, 8 ... Outer air ejection pipe, 9,9
a, 9b …… Inner air jet pipe, 10,11 …… Piping, 13,33 …… Air compressor, 20 …… Jellyfish, 21,34 …… Bubbles.

Claims (3)

(57) [Claims] 1. A curtain wall which is provided on a water intake side of a water intake opening with a space between the curtain and a water bottom, and which surrounds the curtain wall and extends from a vicinity of an upper end of the curtain wall to a lower outside of the curtain wall. A net extending obliquely toward the bottom and having a space between the lower edge and the water bottom,
In the jellyfish inflow prevention device, which is located outside the lower edge of the net and has an outer air ejection pipe disposed at a height lower than the lower edge of the net, the tension angle of the net is Jellyfish inflow to the intake, which is 50 ° or more to the bottom of the water, and the inner air ejection pipe is arranged in the section between the lower end of the curtain wall and the lower edge of the net in the plane arrangement. Prevention device. 2. The jellyfish inflow prevention device according to claim 1, wherein an angle of the lower edge of the net seen from the outer air ejection pipe is 50 ° or more with respect to the water bottom. 3. The height from the bottom of the water to the lower edge of the net is
The jellyfish inflow prevention device according to claim 1 or 2, wherein the height is lower than the height from the water bottom to the lower end of the curtain wall.