JP6026358B2 - Backwashing apparatus and method for seafloor seepage water intake equipment - Google Patents

Description

  TECHNICAL FIELD The present invention relates to a backwashing apparatus and a method for backwashing a sand filtration layer by periodically backflowing seawater introduced in a seabed permeation water intake facility that introduces seawater taken into the seabed through a sand filtration layer. Is.

  Conventionally, in this kind of submarine infiltration water intake equipment, as shown in Patent Document 1, for example, one end side of a water collecting pipe is embedded in a sand filtration layer installed on the sea bottom, and the sand filtration layer is naturally infiltrated from the ocean. Seawater taken into the water collection pipe is introduced into the water conduit. The other end of the water collecting pipe is connected via a second gate valve to the bottom of a water tank installed at a higher position than the ocean tide level. One end of the water conduit is connected to the middle of the water collecting pipe (one end side of the second gate valve), and the other end is connected to the pump inlet through the first gate valve and the pressure switch. In addition, a water supply pipe for supplying seawater to the seawater treatment facility is connected to the discharge port of the pump. One end of a water supply pipe for supplying a part of seawater to the water storage tank is connected to the water supply pipe. Seawater introduced into the water conduit from the intake pipe by the operation of the pump is supplied to the water storage tank through the water supply pipe and the water supply pipe and stored. When the pressure switch detects that the amount of seawater collected from the water pipe has decreased, the first gate valve is closed and the second gate valve is opened, and the seawater stored in the water storage tank flows back into the water collection pipe. The sand filtration layer is backwashed by the backflowing seawater.

Japanese Examined Patent Publication No. 6-36848

  However, the conventional backwashing device requires a pump for feeding seawater necessary for backwashing to a high place when backflowing seawater from a high-level water tank. Moreover, when the sand filtration layer is automatically backwashed, detection means such as a pressure switch for detecting a decrease in the amount of collected seawater from the water pipe is required. For this reason, the cost of the backwashing apparatus increases and energy saving cannot be achieved.

  This invention is made | formed in view of this point, The place made into the objective is to provide the backwash apparatus of the seawater treatment facility which can aim at energy saving, aiming at cost reduction, and its method. .

  In order to achieve the above-mentioned object, in the present invention, a water intake pipe is embedded in a sand filtration layer installed on the seabed, and the seawater taken into the intake pipe through natural penetration of the sand filtration layer from the ocean is introduced from the water conduit. In the submarine infiltration water intake facility, a backwashing device for backwashing the sand filtration layer by periodically backflowing seawater from the water guide pipe to the water intake pipe is assumed. Furthermore, while communicating with the ocean at the time of rising tide, it is isolated at the time of lowering tide, and is connected between the seawater storage portion for storing the isolated seawater, the conduit and the seawater storage portion, and the seawater between the two And a connecting pipe having switching means for switching between a permissible position allowing the flow of the air and a shut-off position for shutting off. In addition, the seawater storage unit can store seawater at a water level sufficient to cause a water head difference in which the sand filtration layer can be backwashed with respect to the ocean tide level at the time of lower tide. Then, the switching means is configured to connect the seawater in the seawater storage section when a water head difference in which the sand filtration layer can be backwashed is generated between the tide level of the ocean descending due to the lower tide and the water level of the seawater storage section. It is characterized by switching to the permissible position so as to reversely flow through the tube.

  Further, the backwash residual seawater remaining by backwashing between the intake pipe and the connecting pipe is caused by the seawater taken from the intake pipe when the switching means is changed from a low tide to a rising tide. You may switch to the interruption | blocking position, when all are pushed back to the storage part.

  Further, a communication pipe having a communication switching means for switching between an allowable position allowing the flow of seawater between the seawater storage section and the ocean and a blocking position for blocking between the seawater storage section and the ocean is provided. . The communication switching means may be switched to the permissible position when the switching means is switched from the lower tide to the rising tide and the switching means is switched to the blocking position.

  On the other hand, the seawater reservoir is communicated with the ocean through the intake pipe, the water conduit, and the connecting pipe. The switching means is changed from a low tide to a high tide, and seawater at a water level sufficient to cause a back-washable water head difference of the sand filtration layer with respect to the sea tide level during the low tide is stored in the seawater storage section. It may be switched to an allowable position until

  In addition, replenishment for replenishing the seawater reservoir with seawater when the head difference between the ocean tide descending due to lower tide and the water level of the seawater reservoir is less than the backflushable head difference of the sand filtration layer. Means may be provided.

  Moreover, it is preferable to set the water head difference of the said sand filtration layer which can be backwashed to 600 mm or more.

  Further, the seawater reservoir stores water volume seawater obtained by adding a backwash water amount corresponding to the time required for backwashing of the sand filtration layer to the water head difference with respect to the low tide level position of the ocean at low tide. And when the said sand filter layer is backwashed, it is preferable to switch the said switching means to a permissible position in the state holding the water head difference which the sand filter layer can backwash.

  In order to achieve the above object, according to the present invention, a water intake pipe is embedded in a sand filtration layer installed on the seabed, and the water taken into the intake pipe by naturally penetrating the sand filtration layer from the ocean is introduced into the water intake pipe. In the submarine infiltration water introduction system introduced from the above, it is assumed that the sand filtration layer is backwashed by periodically backflowing seawater from the water conduit to the water intake pipe. And the seawater storage part which communicates at the time of rising tide with respect to the ocean and stores seawater is isolated from the ocean at the time of tide. Thereafter, when a water head difference that can be backwashed in the sand filtration layer occurs between the ocean tide descending due to the lower tide and the water level of the seawater storage unit, the water pipe is connected between the water conduit and the seawater storage unit. It is characterized by allowing reverse flow of seawater through the connected pipe.

  In short, the seawater in the seawater storage part flows back from the water conduit to the intake pipe when there is a head difference that can be backwashed in the sand filtration layer between the sea level that falls due to the lower tide and the water level in the seawater storage part. By doing so, the sand filtration layer is regularly backwashed according to the lower tide. For this reason, a pump for feeding seawater necessary for backwashing to a high place and a detecting means for detecting a decrease in the amount of collected seawater are not required. Thereby, energy saving can be achieved, aiming at the cost reduction of a backwashing apparatus.

It is a top view which shows schematic structure of the seabed seepage water intake equipment provided with the backwashing apparatus which concerns on the 1st Embodiment of this invention. (A) is sectional drawing which shows schematic structure of the seabed seepage water intake equipment of FIG. 1, (b) has each shown sectional drawing of the sand filtration layer. It is explanatory drawing which shows the model of the backwashing experiment which performed the backwashing based on the water head difference from the intake pipe embedded in the sand filtration layer. It is a Japan map which shows the acquisition point of tide data in Japan. FIG. 5 is a characteristic diagram showing tide data at each acquisition point in FIG. 4. It is a map of the Asia-Oceania region showing the points of tidal data acquisition in each country of the Asia-Oceania region. It is a characteristic view which shows the tide data in each acquisition point of FIG. This is a map of Africa, Europe and America showing the points of tidal data acquisition in each country in Africa, Europe and America. It is a characteristic view which shows the tide data in each acquisition point of FIG. It is sectional drawing which shows the seepage water intake process by the seabed seepage water intake equipment of FIG. It is sectional drawing which shows the preparation start time of the backwashing process by the backwashing apparatus of the seabed seepage water intake equipment of FIG. It is sectional drawing which shows the start time of the backwashing process by the backwashing apparatus of FIG. It is sectional drawing which shows the progress state of the backwashing process by the backwashing apparatus of FIG. It is sectional drawing which shows the completion | finish time of the backwashing process by the backwashing apparatus of FIG. It is sectional drawing which shows the start time of the pushing-back process of the backwashing residual seawater by the backwashing apparatus of FIG. It is sectional drawing which shows the progress state of the push-back process of the backwashing residual seawater by the backwashing apparatus of FIG. It is sectional drawing which shows the completion | finish time of the push-back process of the backwashing residual seawater by the backwashing apparatus of FIG. It is sectional drawing which shows the state which finished the push-back process of the backwash residual seawater by the backwash apparatus of FIG. 17, and changed to the seepage water intake process by a seabed seepage water intake equipment. It is a top view which shows schematic structure of the seabed seepage water intake equipment provided with the backwashing apparatus which concerns on the modification of 1st Embodiment. It is sectional drawing which shows schematic structure of the seabed seepage water intake equipment provided with the backwashing apparatus which concerns on the 2nd Embodiment of this invention. It is sectional drawing which shows the seepage water intake process of the seabed seepage water intake equipment of FIG. It is a vertical side view which shows the preparation start time of the backwashing process by the backwashing apparatus of the seabed seepage water intake equipment of FIG. It is sectional drawing which shows the start time of the backwashing process by the backwashing apparatus of FIG. It is sectional drawing which shows the progress state of the backwashing process by the backwashing apparatus of FIG. It is sectional drawing which shows the completion | finish time of the backwashing process by the backwashing apparatus of FIG. It is sectional drawing which shows the state which finished the backwashing process by the backwashing apparatus of FIG. 25, and transfered to the infiltration water intake process by a seabed infiltration water intake equipment. It is sectional drawing which shows schematic structure of the seabed seepage water intake equipment provided with the backwashing apparatus which concerns on the modification of 2nd Embodiment.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a plan view showing a schematic configuration of a submarine infiltration water intake facility equipped with a backwashing apparatus according to a first embodiment of the present invention, and FIG. 2A is a schematic configuration of the submarine infiltration water intake facility of FIG. Sectional drawing to show, (b) has each shown sectional drawing of the sand filtration layer.

  In FIG. 1 and FIG. 2A, reference numeral 1 denotes a submarine infiltration water intake facility. The undersea infiltration water intake facility 1 provides intake seawater to a treatment plant X that processes seawater. The seabed infiltration water intake facility 1 is composed of a winding screen embedded in a sand filtration layer 2 that is installed by excavating a substantially rectangular region 29 of the seabed 20 and arranged in parallel in the short direction at equal intervals. A plurality of water intake pipes 11, a water collection pipe 12 to which the open ends of the water intake pipes 11 are respectively connected, and one end thereof is connected to a substantially intermediate position in the axial direction of the water collection pipe 12, and naturally penetrates the sand filtration layer 2 from the ocean. Then, a water guide pipe 13 for introducing seawater taken into the water intake pipe 11 via the water collection pipe 12, a water intake tower 14 having a lower end connected to the other end of the water pipe 13 and extending in a substantially vertical direction, and the water intake A water intake pump 15 provided at the lower end in the tower 14, and a feed pipe 16 having one end connected to the discharge port of the water intake pump 15 and supplying the seawater led to the water intake tower 14 to the treatment plant X I have. In this case, the treatment plant X can be applied to any treatment plant such as a treatment plant that desalinates seawater, as well as a treatment plant that purifies seawater for salt production, aquaculture, marine product distribution facilities, or ship ballast water. It is.

  Moreover, as shown in (b) of FIG. 2, the sand filtration layer 2 in which each intake pipe 11 is embedded is composed of a first layer 21 to a fifth layer 25 in order from the top. The fifth layer 25 as the lowermost layer is formed with gravel having a diameter of 12 to 20 mm to a layer thickness of approximately 200 mm, and each intake pipe 11 is embedded in the fifth layer 25. The fourth layer 24 is formed with gravel having a diameter of 6 to 12 mm to a layer thickness of about 100 mm. The third layer 23 is formed with gravel with a diameter of 3 to 6 mm to a layer thickness of about 100 mm. The second layer 22 is formed to have a layer thickness of about 100 mm by gravel having a diameter of 2 to 4 mm. The first layer 21 is formed with a layer thickness of about 600 mm by filtered sand having a diameter of 0.6 mm or less. And the seawater which naturally infiltrated the inside of the sand filtration layer 2 from the ocean and taken into each intake pipe 11 is collected in the water collection pipe 12, introduced into the intake tower 14 from the water guide pipe 13, and discharged from the intake pump 15 Then, it is fed to the processing plant X through the feeding pipe 16.

  Further, the seabed infiltration water intake facility 1 includes a backwashing device 3 that backwashes the sand filtration layer 2 by causing seawater to periodically flow back from the water conduit 13 to each water intake tube 11. The backwashing device 3 includes a seawater storage unit 31 that stores seawater, a connecting pipe 32 that has one end connected to the water conduit 13 via the intake tower 14, and the other end that opens to the seawater storage unit 31, and one end that is offshore. And a communication pipe 33 having the other end opened to the seawater reservoir 31.

  The seawater storage unit 31 is provided in a recess on the coast and shields the intrusion of seawater from the ocean beyond the bank 34 by a bank 34 slightly lower than the high tide position HW at high tide. The seawater storage unit 31 communicates with the ocean at the time of rising tide exceeding the height of the embankment 34, while being isolated at the time of lowering tide below the height of the embankment 34, and the isolated seawater is stored. The seawater storage unit 31 can store seawater having a water level S sufficient to cause a backwashable water head difference Δh of the sand filtration layer 2 with respect to the ocean tide level at the time of lower tide. Further, the water level S of the seawater storage unit 31 corresponds to the amount of backwashing water in order to secure the amount of backwashing water that can be continuously backwashed until the time required for backwashing (for example, about 20 minutes) elapses. Seawater with a water volume (Δh + Vbw) obtained by adding the backwash water height Vbw and the head difference Δh is required for the low tide position LW at low tide. Note that HHW in FIG. 2 indicates the maximum high tide position at high tide at high tide, and LLW indicates the minimum low tide position at low tide at high tide.

  The connecting pipe 32 is a switching means that switches between a permissible position allowing passage of seawater between the water guide pipe 13 and the seawater reservoir 31 via the intake tower 14 and a shutoff position for shutting off, so that the opening degree can be adjusted. The opening degree adjustment valve 35 is provided. In addition, the communication pipe 33 includes a communication opening / closing valve 36 as a communication switching means that switches between a permissible position that allows the flow of seawater between the ocean and the seawater storage unit 31 and a blocking position that blocks the seawater. The opening adjustment valve 35 and the communication opening / closing valve 36 are connected to a controller (not shown) and are automatically switched according to the tide level due to the ocean tide based on the tide table input from the Japan Meteorological Agency or Japan Hydrographic Society.

  Here, the backwashable water head difference Δh of the sand filtration layer 2 between the ocean tide level and the water level S of the seawater reservoir 31 will be described with reference to FIG. 3. FIG. 3 shows an explanatory diagram showing a model of a backwashing experiment in which backwashing is performed based on the water head difference Δh from the intake pipe 11 embedded in the sand filtration layer 2.

  In FIG. 3, the water tank P is provided with the sand filtration layer 2 similarly configured by the first layer 21 to the fifth layer 25 in order from the top, and the intake pipe 11 is embedded in the lowermost layer (fifth layer 25). ing. Backwash water is supplied to the water intake pipe 11 through the pipe 18 by operating a water supply pump (not shown) from a water tank 17 as a backwash water supply source to the water tank P, and the flow rate of the backwash water is 36 m. Various changes were made within the range of / h to 54 m / h, and the expansion rate and pressure loss during backwashing of the first layer 21 were measured. In this case, the head loss Δh between the water head H1 of the water storage tank 17 and the water level H2 on the sand filtration layer 2 was defined as the pressure loss. The water in the water tank P overflowed by the backwash water at the time of backwashing was discharged to the outside through the pipeline 19 from the overflow hole 19a.

Table 1 below shows the expansion rate and pressure loss of the first layer 21 when the sand filtration layer 2 is backwashed. The expansion rate of the first layer 21 is an apparent expansion rate that appears to be lifted up by the backwash water during backwashing.

  From this measurement result, based on the knowledge (water supply facility design guideline 2012: p.222) that an apparent expansion rate of about 20% by backwashing the first layer 21 is sufficient, the head of the water tank 17 It can be seen that the water head difference Δh between H1 and the water level H2 on the sand filtration layer 2 should be 600 mm or more. Therefore, in the present embodiment, the backwashable water head difference Δh of the sand filtration layer 2 between the ocean tide level W and the water level S of the seawater storage unit 31 when rising from low tide to low tide is set to 600 mm.

  Next, tide data acquisition points in Japan and tide data acquisition points around the world will be described.

  FIG. 4 is a map of Japan showing the tide data acquisition points in Japan, and FIG. 5 is a characteristic diagram showing the tide data at each acquisition point of FIG. FIG. 6 is a map of the Asia / Oceania region showing tide data acquisition points in each country of the Asia / Oceania region, and FIG. 7 is a characteristic diagram showing tide data at each acquisition point in FIG. 8 is a map of Africa / Europe / America / America showing the tide data acquisition points in each country in Africa / Europe / America, and FIG. 9 is a characteristic chart showing the tide data at each acquisition point in FIG. Show.

  4 and 5, of the tide data acquisition points a1 to a47 in Japan, the points a1, a3, a9, a12, a14, a15, a21, and a24 on the Sea of Japan side indicate the ocean tide level W. Since the maximum height difference Max (HW-LW) and the minimum height difference Min (HW-LW) are both less than 600 mm, the determination is indicated by x. In addition, at points a2, a4 to a8, a10, a11, a13, a20, a25, a28, a40, a47 indicated by Δ, the minimum height difference Min (HW-LW) of the ocean tide level is less than 600 mm (60 cm). Although the maximum height difference Max (HW−LW) exceeds 600 mm, Δ is given to the determination. Further, at points a16 to a19, a22, a23, a26, a27, a29 to a39, and a41 to a46 indicated by ◯, the maximum height difference Max (HW-LW) and the minimum height difference Min (HW-LW) ) Is over 600 mm, both of which are given ◎.

  6 and 7, among the tidal data acquisition points b1 to b36 in each country in the Asia / Oceania region, at b36, the maximum height difference Max (HW−LW) and the minimum height difference Min (HW) of the sea tide level W are shown. Since -LW) is less than 600 mm (60 cm), the determination is indicated by a cross. In addition, at points b7 to b12, b18 to b22, b25, b26, b29, b31, b32, b34, and b35 indicated by Δ, the maximum altitude difference Min (HW-LW) of the ocean tide level is less than 600 mm. Since the height difference Max (HW−LW) exceeds 600 mm, Δ is given to the determination. Furthermore, at points b1 to b6, b13 to b17, b23, b24, b27, b28, b30, and b33 indicated by ◯, the maximum height difference Max (HW-LW) and the minimum height difference Min (HW-LW) ) Is over 600 mm, both of which are given ◎.

  8 and 9, among the tidal data acquisition points c1 to c44 in each country in Africa, Europe, and the United States, c9, c11, c25, and c32 are the maximum height difference Max (HW−LW) of the sea tide level W. ) And the minimum height difference Min (HW−LW) are both less than 600 mm (60 cm), and therefore, the determination is indicated by a cross. Further, at points c3, c8, c10, c12, c24, c26 to c31, c33, c36, c37, c41, and C42 indicated by Δ, the minimum height difference Min (HW−LW) of the ocean tide level is less than 600 mm. Since the maximum height difference Max (HW-LW) of the object exceeds 600 mm, Δ is given to the determination. Further, at the points c1, c2, c4 to c7, c13 to c23, c34, c35, c38 to c40, c43, and c44 indicated by ○, the maximum height difference Max (HW−LW) and the minimum height difference Min of the sea tide level are displayed. Since both (HW-LW) exceeds 600 mm, 判定 is given to the determination.

  Next, an example of the backwashing method by the backwashing apparatus 3 will be described with reference to FIGS.

  FIG. 10 is a cross-sectional view showing an osmotic water intake process by the seabed osmotic water intake facility 1, FIG. 11 is a cross sectional view showing a preparation start point of a backwash process by the backwash device 3 of the seabed osmotic water intake facility 1, and FIG. Sectional drawing which shows the start time of the backwash process by each is shown. 13 is a cross-sectional view showing the progress of the backwashing process by the backwashing device 3, FIG. 14 is a cross-sectional view showing the end of the backwashing process by the backwashing device 3, and FIG. 15 is a backwashing by the backwashing device 3. Sectional drawing which shows the start time of the pushing-back process of residual seawater is shown, respectively. 16 is a cross-sectional view showing the progress of the backwashing residual seawater push-back process by the backwashing apparatus 3, FIG. 17 is a cross-sectional view showing the end of the backwashing residual seawater pushback process by the backwashing apparatus 3, and FIG. FIG. 2 shows a cross-sectional view showing a state where the backwashing residual seawater pushing back process by the backwashing device 3 is finished and the state is shifted to the permeate water intake process by the seabed infiltration water intake facility 1.

  In FIG. 10, the ocean tide level W is at a normal high tide position HW, and the transition from the high tide position HW to a lower tide begins. At this time, as for the connection pipe 32, the opening degree adjustment valve 35 is switched to the interruption | blocking position, and the distribution | circulation of the seawater between the water guide pipe 13 and the seawater storage part 31 is interrupted | blocked. On the other hand, in the communication pipe 33, the communication on / off valve 36 is switched to the permissible position, and the circulation of seawater between the ocean and the seawater storage unit 31 is permitted. Then, the infiltration water intake process is performed by the sea bottom infiltration water intake facility 1, and the seawater naturally infiltrated into the sand filtration layer 2 from the ocean and taken into each intake pipe 11 is collected in the water collection pipes 12, and the water guide pipes 13. From the discharge port of the water intake pump 15 to the treatment plant X via the supply pipe 16.

Next, as shown in FIG. 11, the water level S of the seawater storage unit 31 that descends with the tide level of the ocean due to the low tide is the water volume obtained by adding the head difference Δh and the backwash water height Vbw to the low tide position LW. When it becomes (Δh + Vbw), the preparation for the backwashing process is started. That is, the communication on / off valve 36 is switched to the cutoff position, and the circulation of seawater between the ocean and the seawater storage unit 31 via the communication pipe 33 is blocked.
At this time, seawater that naturally permeates through the sand filtration layer 2 from the ocean and is taken into each intake pipe 11 is introduced into the collecting pipe 12, the water guide pipe 13, and the intake tower 14, and is supplied from the discharge port of the intake pump 15. The osmotic water intake step of supplying seawater to the treatment plant X via the pipe 16 is continuously performed.

Thereafter, as shown in FIG. 12, the ocean tide level is lowered by the lower tide, and the backwashable water head difference Δh (600 mm) of the sand filtration layer 2 is between the ocean tide level W and the water level S of the ocean reservoir 31. When it occurs, the backwash process is started. In other words, the opening adjustment valve 35 is switched to the permissible position side, and the circulation of seawater between the water guide pipe 13 and the seawater storage part 31 via the connecting pipe 32 is permitted.
Moreover, when the opening degree adjustment valve 35 is switched to the allowable position side, the water intake pump 15 is stopped and the infiltration water intake process by the seabed infiltration water intake facility 1 is interrupted. That is, the supply of the seawater (unfiltered seawater by the sand filtration layer 2) flowing from the seawater storage unit 31 to the intake tower 14 via the connecting pipe 32 is prohibited from being supplied to the processing plant X. Yes.

At this time, as shown in FIG. 13, the opening adjustment valve 35 is adjusted so that the lowering of the water level S in the ocean storage section 31 is slightly delayed from the lowering of the sea tide W due to the lower tide. And the water level difference Δh of the sand filtration layer 2 that can be backwashed is always kept between the water level S of the ocean reservoir 31. Thereby, a pressure loss of 600 mmH ₂ O is always expected between the ocean tide level W and the water level S of the ocean reservoir 31, and the sand filtration layer 2 can be backwashed smoothly.

  Thereafter, as shown in FIG. 14, the ocean tide level W reaches the low tide level position LW, and the water level S of the ocean reservoir 31 is backwashed between the two at the low tide level position LW. When the possible head difference Δh is reached, the opening adjustment valve 35 is switched to full open (allowable position) without adjusting the opening, and when the water level S of the ocean reservoir 31 is balanced with the low tide position LW, The backwash process is terminated. Thereby, the sand filtration layer 2 is regularly backwashed according to the lower tide. For this reason, a pump for supplying seawater necessary for backwashing to a high place and a pressure switch for detecting a decrease in the amount of collected seawater are not required, and energy saving can be achieved while reducing the cost of the backwashing device 3. it can.

  Thereafter, as shown in FIGS. 15 and 16, when the ocean tide level W begins to rise due to rising tide, it remains in the intake pipe 11, the water collection pipe 12, the water conduit 13 and the intake tower 14 during the backwashing process. The pushing back process which pushes back the backwashing residual seawater which is back to the seawater storage part 31 is started. That is, the backwash residual seawater remaining in the intake pipe 11, the water collection pipe 12, the water guide pipe 13, and the intake tower 14 naturally permeates through the sand filtration layer 2 from the ocean as the ocean tide level W rises. The seawater taken into the intake pipe 11 is pushed back to the seawater storage part 31 via the connecting pipe 32 in the order of the water collection pipe 12, the water guide pipe 13 and the water intake tower 14.

  Then, as shown in FIG. 17, when all the backwash residual seawater is pushed back to the seawater reservoir 31 through the connecting pipe 32 and the pushback process is completed, the opening adjustment valve 35 is switched to the shut-off position, Circulation of seawater through the connecting pipe 32 with the seawater storage unit 31 is blocked. Completion of the backwashing residual seawater push-back process is performed by connecting the seawater via the connecting pipe 32 with a water level sensor attached to the seawater reservoir 31 or a flow rate sensor for detecting the circulation of seawater attached to the opening adjustment valve 35. The total amount of backwash residual seawater pushed back to the storage unit 31 is detected. As a result, the intake pipe 11, the water collection pipe 12, the water guide pipe 13, and the intake tower 14 are filled with seawater that naturally permeates the sand filtration layer 2 from the ocean.

  When the push-back process is completed and the opening adjustment valve 35 is switched to the shut-off position, the water intake pump 15 is activated and the infiltration water intake process by the submarine infiltration water intake facility 1 is resumed. Thereby, the seawater which naturally permeated the sand filtration layer 2 from the ocean can be supplied to the treatment plant X.

  Further, simultaneously with the switching of the opening adjustment valve 35 to the shut-off position, the communication on-off valve 36 is switched to the permissible position, and the circulation of seawater between the ocean and the seawater storage unit 31 via the communication pipe 33 is permitted. Thereby, the seawater in the ocean can be distributed to the seawater reservoir 31 via the communication pipe 33, and the seawater can be stored in the seawater reservoir 31 while being balanced with the tide level of the seawater reservoir 31.

  Thereafter, as shown in FIG. 18, the water level S of the seawater reservoir 31 rises in equilibrium with the sea tide level W rising due to the rising tide, and the seawater that has naturally permeated the sand filtration layer 2 from the ocean is treated with the treatment plant X. The permeate intake process to be sent to

  In the present embodiment, the seawater reservoir 31 in which the coastal recess is shielded by the embankment 34 is provided. However, as shown in FIG. A seawater storage tank 37 serving as a seawater storage section capable of storing seawater at a water level S having a water volume (Δh + Vbw) obtained by adding a backwash water height Vbw to a backwashable water head difference Δh is provided separately from the ocean. A communication pipe 33 having a communication opening / closing valve 36 may be provided between the storage tank 37 and the ocean.

  Next, a second embodiment of the present invention will be described with reference to FIGS.

  In this embodiment, the height of the bank is changed. The other configurations except the bank are the same as those in the first embodiment, and the same portions are denoted by the same reference numerals and detailed description thereof is omitted.

FIG. 20: has shown sectional drawing which shows schematic structure of the seabed seepage water intake equipment 1 provided with the backwashing apparatus which concerns on the 2nd Embodiment of this invention.
In FIG. 20, the seawater storage part 51 is provided in the recessed part of the shore, is isolated from the ocean by the embankment 52 higher than the maximum high tide position HHW at the tidal current, and reliably shields the intrusion of seawater from the ocean.

  Next, an example of the backwashing method by the backwashing apparatus 3 will be described based on FIGS. 21 to 26 together with the infiltration water intake method by the seabed infiltration water intake facility 1.

  FIG. 21 is a cross-sectional view showing an osmotic water intake process of the seabed osmotic water intake facility 1, FIG. 22 is a cross sectional view showing a preparation start point of the backwash process by the backwash device 3 of the seabed osmotic water intake facility 1, and FIG. Sectional drawing which shows the start time of the backwash process by each is shown. 24 is a cross-sectional view showing the progress of the backwashing process by the backwashing device 3, FIG. 25 is a cross-sectional view showing the end of the backwashing process by the backwashing device 3, and FIG. Sectional drawing which shows the state which finished the process and changed to the seepage water intake process by the seabed seepage water intake equipment 1 is shown, respectively.

  In FIG. 21, the tide level of the ocean is at the normal high tide position HW, and the transition to the low tide starts from this high tide position HW. At this time, as for the connection pipe 32, the opening degree adjustment valve 35 is switched to the permissible position, and the circulation of the seawater between the water guide pipe 13 and the seawater reservoir 51 is permitted. On the other hand, in the communication pipe 33, the communication on / off valve 36 is switched to the blocking position, and the circulation of seawater between the ocean and the seawater storage unit 51 is blocked. Then, the infiltration water intake process by the undersea infiltration water intake facility 1 is performed. The seawater naturally infiltrated into the sand filtration layer 2 from the ocean and taken into each intake pipe 11 is collected in the water collection pipes 12 and is introduced into the water guide pipe 13. Is introduced into the intake tower 14 and circulates in the seawater storage 51 via the connecting pipe 32, and is supplied from the discharge port of the intake pump 15 to the treatment plant X via the supply pipe 16.

Next, as shown in FIG. 22, the water level S of the seawater storage section 51 that descends with the ocean tide level due to the lower tide is the water volume obtained by adding the head difference Δh and the backwash water height Vbw to the low tide position LW. When it becomes (Δh + Vbw), the preparation for the backwashing process is started. That is, the communication on / off valve 36 is switched to the cutoff position.
At this time, seawater that naturally permeates through the sand filtration layer 2 from the ocean and is taken into each intake pipe 11 is introduced into the collecting pipe 12, the water guide pipe 13, and the intake tower 14, and is supplied from the discharge port of the intake pump 15. The osmotic water intake step of supplying seawater to the treatment plant X via the pipe 16 is continuously performed.

Thereafter, as shown in FIG. 23, the ocean tide level is lowered by the lower tide, and a water head difference Δh (600 mm) capable of backwashing the sand filtration layer 2 is generated between the ocean tide level and the water level S of the ocean reservoir 51. The backwash process is started. In other words, the opening adjustment valve 35 is switched to the permissible position side, and the circulation of seawater between the water guide pipe 13 and the seawater storage part 31 via the connecting pipe 32 is permitted.
Moreover, when the opening degree adjustment valve 35 is switched to the allowable position side, the water intake pump 15 is stopped and the infiltration water intake process by the seabed infiltration water intake facility 1 is interrupted.

At this time, as shown in FIG. 24, the opening adjustment valve 35 is adjusted so that the lowering of the water level S in the ocean storage section 51 is slightly delayed from the lowering of the sea tide due to the lower tide. Between the water level S of the storage part 51, the water head difference Δh of the sand filtration layer 2 that can be backwashed is always maintained. As a result, a pressure loss of 600 mmH ₂ O is always expected between the ocean tide level and the water level S of the ocean reservoir 51, and the sand filtration layer 2 can be backwashed smoothly.

  After that, as shown in FIG. 25, the ocean tide level W reaches the low tide level position LW, and the water level S of the ocean reservoir 31 is backwashed between the low tide level position LW and the sand filtration layer 2 therebetween. When the possible head difference Δh is reached, the opening adjustment valve 35 is switched to full open (allowable position) without adjusting the opening, and when the water level S of the ocean reservoir 31 is balanced with the low tide position LW, The backwash process is terminated. Thereby, the sand filtration layer 2 is regularly backwashed according to the lower tide. For this reason, a pump for supplying seawater necessary for backwashing to a high place and a pressure switch for detecting a decrease in the amount of collected seawater are not required, and energy saving can be achieved while reducing the cost of the backwashing device 3. it can.

Then, as shown in FIG. 26, when the sea tide level rises as a rising tide, the seawater naturally infiltrated into the sand filtration layer 2 from the sea and taken into the intake pipes 11 is collected into the collecting pipes 12, The water guide pipe 13 and the intake tower 14 are introduced in this order, and are circulated to the seawater reservoir 51 via the connecting pipe 32. At this time, the water intake pump 15 is operated, and seawater is supplied to the treatment plant X through the supply pipe 16 from the discharge port.
As a result, only the seawater naturally infiltrated into the sand filtration layer 2 from the ocean and taken into each intake pipe 11 is stored in the seawater reservoir 51, and the sand filtration from the ocean is performed without the need for a backwashing process of the backwash residual seawater. Seawater that has naturally permeated through the layer 2 can be quickly supplied to the treatment plant X.

  In the present embodiment, since the communication on / off valve 36 is always switched to the cutoff position, the communication pipe 33 may be eliminated.

Further, in the present embodiment, the seawater reservoir 51 is provided to isolate the coastal recess from the ocean by the dike 52 higher than the maximum high tide position HHW. However, as shown in FIG. In contrast, the seawater storage tank 53 as a seawater storage section capable of storing seawater at a water level S sufficient to cause a backwashable water head difference Δh of the sand filtration layer 2 is isolated together with the seawater storage section 51 from the ocean. It may be provided. A connection auxiliary pipe 54 is provided between the seawater storage tank 53 and the intake tower 14, and the connection auxiliary pipe 54 is a permissible position that allows circulation of seawater between the intake tower 14 and the seawater storage tank 53. And an opening adjusting valve 55 that switches between the shut-off position and the shut-off position to be adjustable. In addition, the opening adjustment valve 55 is switched to a permissible position at high tide at high tide and the seawater storage tank 53 flows into the seawater storage tank 53 through the connection auxiliary pipe 54. Seawater at the same water level S as the high tide position HHW is stored.
Then, when the head difference between the ocean tide level W and the water level S of the seawater reservoir 51, which is lowered by the lower tide, is less than the backwashable head difference Δh of the sand filtration layer 2, for example, at low tide, etc. The degree adjustment valve 35 is switched to the cutoff position, the reverse flow of seawater between the water guide pipe 13 and the seawater storage part 31 via the connection pipe 32 is shut off, and the opening degree adjustment valve 55 is switched to the allowable position side to assist the connection. The reverse flow of seawater between the intake tower 14 and the seawater storage tank 53 via the pipe 54 is allowed. As a result, even when the tide is low, backwashing of the sand filtration layer 2 is smoothly performed in a state where a pressure loss of 600 mmH ₂ O is always expected between the ocean tide level W and the water level S in the ocean storage tank 53. Can be done.

  Further, when the water head difference between the sea tide level W descending due to the lower tide and the water level S of the seawater storage section 51 is less than the water head difference Δh of the sand filtration layer 2 that can be backwashed, Replenishment means for replenishing may be provided. This replenishing means may be constituted by a connection auxiliary pipe 54 having an opening degree adjusting valve 55 between the seawater storage tank 53 and the seawater storage part 51 in the modification. And at the time of a low tide, etc., by switching the opening adjustment valve 55 to the permissible position side and allowing the seawater circulation between the seawater storage part 51 and the seawater storage tank 53 via the connection auxiliary pipe 54, If seawater from the seawater storage tank 53 is replenished to the seawater storage part 51 until the water head difference between the sea tide level W and the water level S of the seawater storage part 51 becomes the head difference Δh of the sand filtration layer 2 that can be backwashed. Good.

  Furthermore, the replenishment means is connected to the intake pump provided in the intake tower, one end connected to the discharge port of the intake pump, the other end connected to the seawater storage section, and between the intake tower and the seawater storage section. You may be comprised with the connection pipe | tube which has the on-off valve which switches to the permissible position which accept | permits the distribution | circulation of seawater, and the interruption | blocking position which interrupts | blocks. And at the time of low tide etc., the intake pump is operated and the on-off valve is switched to the permissible position side, allowing the circulation of seawater between the intake tower and the seawater reservoir through the connecting pipe, Seawater may be replenished to the seawater reservoir until the waterhead difference between the tide level W and the water level S of the seawater reservoir becomes the waterhead difference Δh at which the sand filtration layer can be backwashed. In this case, the backwashing device of the sea bottom infiltration water intake facility can be applied even in an area where there is almost no tidal difference due to ocean tides.

DESCRIPTION OF SYMBOLS 1 Submarine seepage water intake equipment 11 Intake pipe 12 Water conveyance pipe 2 Sand filtration layer 20 Sea bottom 3 Backwash apparatus 31 Seawater storage part 32 Connection pipe 33 Communication pipe 35 Opening adjustment valve (switching means)
36 Communication open / close valve (communication switching means)
Δh Backwashable head difference W Ocean tide level S Sea level

Claims (8)

In the sea bottom infiltration water intake facility in which a water intake pipe is embedded in a sand filtration layer installed on the sea floor, and the sea water taken into the water intake pipe is introduced into the water intake pipe through natural penetration of the sand filtration layer from the ocean, A backwashing device for backwashing the sand filtration layer by periodically backflowing seawater from the water conduit to the intake pipe,
A seawater storage unit that communicates with the ocean at the time of rising tide, and is isolated at the time of lowering tide, and stores the isolated seawater;
A connecting pipe that is connected between the water conduit and the seawater storage section, and has a switching means that switches between a permissible position that allows the flow of seawater between the two and a blocking position that shuts off the seawater;
With
In the seawater storage part, seawater at a water level sufficient to cause a head difference that can be backwashed by the sand filtration layer with respect to the sea tide level at the time of lower tide can be stored.
The switching means connects the seawater of the seawater storage section to the seawater storage section when a water head difference that can be backwashed by the sand filtration layer is generated between the sea level lowered by the lower tide and the water level of the seawater storage section. A backwashing device for a submarine infiltration water intake facility, wherein the backwashing device is switched to a permissible position so as to flow backward.   The switching means is configured so that the backwash residual seawater remaining by backwashing from the intake pipe to the connecting pipe is caused by the seawater taken from the intake pipe when the rising tide is changed to the rising tide. The backwashing device for a seabed infiltration water intake facility according to claim 1, wherein the backwashing device is switched to a shut-off position when all of the water is pushed back. Between the seawater storage section and the ocean, a communication pipe having a communication switching means that switches between an allowable position allowing the flow of seawater between the seawater storage section and the ocean and a blocking position for blocking the seawater is provided. ,
The backwashing device for a submarine infiltration water intake facility according to claim 2, wherein the communication switching means is switched to a permissible position when the switching means is switched from a low tide to a rising tide and switched to the cutoff position. The seawater reservoir communicates with the ocean through the intake pipe, the water conduit, and the connecting pipe,
The switching means changes from a low tide to a rising tide until seawater at a water level sufficient to cause a back head washable difference in the sand filtration layer with respect to the sea tide level at the time of the low tide is stored in the seawater reservoir. The backwashing device of the seafloor seepage water intake facility according to claim 1, wherein the backwash device is switched to an allowable position during   Replenishment means for replenishing the seawater reservoir with seawater when a difference in water head between the tide level of the ocean descending due to a lower tide and the water level of the seawater reservoir is less than the backflushable head difference of the sand filtration layer; The backwashing apparatus of the seafloor seepage water intake facility according to any one of claims 1 to 4, which is provided.   The backwashing device of the seabed seepage water intake facility according to any one of claims 1 to 5, wherein a water head difference of the sand filtration layer that can be backwashed is set to 600 mm or more. In the seawater storage part, the seawater of water volume is stored by adding the amount of backwash water for the time required for backwashing of the sand filtration layer to the water head difference with respect to the low tide level position of the ocean at low tide,
The said switching means is switched to a permissible position in the state which kept the water head difference which can be backwashed of the sand filtration layer, when backwashing the sand filtration layer. Backwash equipment for seawater seepage water intake equipment. In a submarine infiltration water intake facility that embeds a water intake pipe in a sand filtration layer installed on the seabed and naturally permeates the inside of the sand filtration layer from the ocean and introduces seawater taken into the intake pipe from the water introduction pipe. A backwashing method for backwashing the sand filtration layer by periodically backflowing seawater into the intake pipe,
The seawater storage part that communicates with the ocean at rising tide and stores seawater is isolated from the ocean at lower tide,
Thereafter, when a water head difference that can be backwashed in the sand filtration layer occurs between the ocean tide descending due to the lower tide and the water level of the seawater storage unit, the water pipe is connected between the water conduit and the seawater storage unit. A backwashing method for seafloor seepage water intake equipment, characterized by allowing backflow of seawater through a connected pipe.

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