JP7664782B2 - Recovery tank system and method of operation thereof - Google Patents

Description

The present invention relates to equipment for recovering underwater sediment, and in particular to a recovery tank system and a method for operating the same.

Various technologies have been proposed for recovering sediment from underwater. In the sand lifting and transporting device disclosed in Patent Document 1, a vacuum generating device is used to suck up the sediment, while compressed air is also used to transport the water and sediment continuously to a sediment recovery section (solid-liquid separation device), where the water and sediment are separated to recover a high concentration of sediment.

In addition, the sediment removal equipment disclosed in Patent Document 2 is provided with a pair of recovery tanks for solid-liquid separation, and by alternately switching between suction and discharge of water, continuous operation of the discharge system is possible.

Patent Publication 2018-158277 Patent Publication 2011-125865

In the discharge system disclosed in the above-mentioned Patent Document 2, when the water level in the first recovery tank reaches an upper limit, it switches to the second recovery tank, during which time the wastewater containing sediment stored in the first recovery tank is discharged, and when the second recovery tank reaches its upper limit, it switches to the first recovery tank, in an alternating operation. For this reason, if there is a difference between the water absorption process time until the recovery tank reaches its upper limit and the water discharge process time until it reaches its lower limit, efficient discharge processing cannot be performed. For example, if the water discharge process time is significantly shorter than the water absorption process time, when water discharge is completed in one recovery tank, it will be in an idle state until the next water absorption begins.

If multiple recovery tanks are to be operated simultaneously, a vacuum suction device with sufficiently high performance must be prepared, but if a large volume of suction is performed, there is a high possibility that the recovery tank will exceed its upper limit and puncture, which will hinder continuous construction. In addition, the increased frequency of the drainage process will cause wear on parts, and the high costs of replacing parts will be unavoidable.

The present invention was devised in consideration of the above circumstances, and the object of the present invention is to provide a recovery tank system and an operating method thereof that can efficiently recover mud and handle large volumes of suction while avoiding high costs.

In order to achieve the above-mentioned object, according to one embodiment of the present invention, there is provided a recovery tank system having a recovery tank that sucks in and discharges muddy water containing sedimentary soil at the bottom of the water, the recovery tank comprising a first tank chamber that sucks in the muddy water by creating a negative pressure inside the recovery tank, and a second tank chamber that is connected to the bottom of the first tank chamber through a first opening/closing valve and has a second opening/closing valve for discharging the muddy water to the bottom, the recovery tank being characterized in that: a) the first opening/closing valve is opened to cause the muddy water that has been sucked into and stored in the first tank chamber to fall into the second tank chamber and be stored in the second tank chamber, b) the first opening/closing valve is closed to store the muddy water that has been sucked into the first tank chamber, c) the second opening/closing valve is opened to discharge the muddy water that has been stored in the second tank chamber, and d) the second opening/closing valve is closed, and continuous operation of the recovery tank is performed by repeating a) to d).
According to one embodiment of the present invention, the first opening/closing valve and the second opening/closing valve are valves that open downward to allow muddy water to fall, and a) to d) can be carried out by changing the air pressure in the first tank chamber and the second tank chamber.
According to one embodiment of the present invention, the system further includes a first control valve for connecting or isolating the first tank chamber and the second tank chamber, a second control valve for connecting or isolating the second tank chamber and the outside, and a valve controller for controlling the opening and closing of the first and second control valves, respectively, and the valve controller can change the air pressure in the first tank chamber and the second tank chamber by controlling the opening and closing of the first and second control valves, respectively, and perform a) to d).
According to one embodiment of the present invention, a configuration is provided in which a plurality of the recovery tanks are arranged in parallel, and the repeating steps a) to d) of each recovery tank can be delayed in time.
In order to achieve the above-mentioned object, according to one embodiment of the present invention, there is provided a method for operating a recovery tank system equipped with a recovery tank that sucks in and discharges muddy water containing sedimentary soil at the bottom of the water, the recovery tank comprising a first tank chamber that sucks in the muddy water by creating a negative pressure inside the tank, and a second tank chamber that is connected to the bottom of the first tank chamber through a first opening/closing valve and has a second opening/closing valve for discharging the muddy water to the bottom, and a valve controller a) opens the first opening/closing valve downward to cause the muddy water sucked into and stored in the first tank chamber to fall into the second tank chamber and be stored in the second tank chamber, b) closes the first opening/closing valve to store the muddy water sucked into the first tank chamber, c) opens the second opening/closing valve downward to discharge the muddy water stored in the second tank chamber, and d) closes the second opening/closing valve, and performs continuous operation of the recovery tank by repeating a) to d).
According to one embodiment of the present invention, the first opening/closing valve and the second opening/closing valve are valves that open downward to allow muddy water to fall, and the valve controller can carry out a) to d) by changing the air pressure in the first tank chamber and the second tank chamber.
According to one embodiment of the present invention, the recovery tank system further includes a first control valve for connecting or isolating the first tank chamber and the second tank chamber, and a second control valve for connecting or isolating the second tank chamber and the outside, and the valve controller controls the opening and closing of the first and second control valves, respectively, to change the air pressure in the first tank chamber and the second tank chamber, thereby carrying out a) to d).
According to one embodiment of the present invention, a configuration is provided in which a plurality of the recovery tanks are arranged in parallel, and the valve controller can delay the repeating steps of a) to d) in each recovery tank in time.

According to one embodiment of the present invention, the recovery tank, which is made up of the first tank chamber and the second tank chamber, is operated continuously by repeating the above-mentioned steps a) to d), which makes mud recovery more efficient and enables large-volume suction while avoiding high costs.
According to one embodiment of the present invention, a)-d) are carried out by changing the air pressure in the first tank chamber and the second tank chamber using first and second opening/closing valves that open downward to allow muddy water to fall, thereby simplifying the configuration for opening and closing control.
According to one embodiment of the present invention, by controlling the opening and closing of the first and second control valves, respectively, to change the air pressure in the first tank chamber and the second tank chamber and execute the above a) to d), the opening and closing control of the first and second opening and closing valves in the tank chamber can be executed by only the first and second control valves, thereby simplifying the configuration for opening and closing control.
According to one embodiment of the present invention, the configuration has multiple recovery tanks arranged in parallel, and by delaying the repeated steps a)-d) of each recovery tank in time, the suction/discharge steps can be executed in parallel and the discharge steps of each recovery tank can be staggered in time. This reduces the capacity of the high concentration transport pump, improves the efficiency of mud recovery, and enables large-volume suction while avoiding high costs.

1 is a schematic configuration diagram of a barge-based sediment recovery facility equipped with a recovery tank system according to a first embodiment of the present invention; 2 is a block diagram showing the configuration of a mud recovery tank in the recovery tank system according to the first embodiment. FIG. 4 is a flowchart showing an example of operation control of the mud recovery tank in the recovery tank system according to the first embodiment. FIG. 4 is a schematic diagram showing an example of operation control of the mud recovery tank in the recovery tank system according to the first embodiment. 4 is a time chart showing five mud absorption/discharge cycles of the mud recovery tank in the recovery tank system according to the first embodiment. 1 is a block diagram showing a configuration of a recovery tank system according to a first embodiment. FIG. 4 is a time chart showing an outline of operation control of the recovery tank system according to the first embodiment. FIG. 11 is a block diagram showing the configuration of a recovery tank system according to a second embodiment of the present invention.

The following describes an embodiment of the present invention with reference to the drawings.

1. First embodiment As illustrated in Fig. 1, the sedimentary soil recovery equipment mounted on a barge 10 is equipment for sucking up sedimentary soil 20 that has accumulated at the bottom of water in rivers, canals, lakes, dam reservoirs, pump sedimentation basins, etc., and recovering the sedimentary soil on the barge 10, and the recovered sedimentary soil is transported to a sedimentation basin on land.

A gate-type facility 11, a recovery tank system 12, a filter 13, a vacuum suction device 14, and a high-concentration transport pump 15 are mounted on the barge 10. The gate-type facility 11 suspends an agitation high-concentration pump 21 by a wire rope 16 so that it can be raised and lowered, and an auger-equipped suction machine 22 attached to the lower end of the agitation high-concentration pump 21 can be lowered to the sedimentary soil 20 at the bottom of the water with a lift h. The sedimentary soil 20 sucked up by the auger-equipped suction machine 22 is agitated by the agitation high-concentration pump 21 and transported to the recovery tank system 12 through a vacuum suction pipe 23, and the absorbed water is transported to the recovery tank system 12 through a pumping transport pipe 24.

The recovery tank system 12 is composed of multiple recovery tanks, a system for controlling the operation of each tank, and a water tank W for storing the discharged muddy water. In this embodiment, a pair of muddy soil recovery tanks T1 and T2 are installed. Each muddy soil recovery tank sucks up muddy soil mixed with water through a vacuum suction pipe 23 in a cycle described below and discharges it into the water tank W. The muddy soil stored in the water tank W is transported to the settling basin by a high-concentration transport pump 15. The suction and discharge of the sedimentary soil 20 is performed by the vacuum suction device 14 creating negative pressure inside the recovery tank through a filter 13, as described below, and the control unit controlling the valve of the muddy soil recovery tank.

The barge 10 is provided with a control room (not shown), where workers can visually or monitor the continuous operation control of the recovery tank system 12, which will be described later, and the operation control of the vacuum suction device 14 and the high-concentration transport pump 15. Next, the configuration and continuous operation of the recovery tank system 12 will be described in detail with reference to Figures 2 to 7.

2, each of the mud recovery tanks T1 and T2 (hereinafter referred to as mud recovery tank T) has a two-tiered structure consisting of an upper tank chamber BL1 and a lower tank chamber BL2. An inlet I and an outlet E are provided on the top surface of the upper tank chamber BL1, and a vacuum suction pipe 23 is connected to the inlet I, and a vacuum suction device 14 is connected to the outlet E.

The bottom surface of the upper tank chamber BL1 has a shape that slopes toward the center, and an opening/closing valve _SV1 that opens only downward is provided at the central lower end. The upper tank chamber BL1 can be connected downward to the lower tank chamber BL2 through the opening/closing valve _SV1 . In this embodiment, the opening/closing valve _SV1 functions like a check valve and naturally opens and closes according to the air pressure difference between the upper tank chamber BL1 and the lower tank chamber BL2, as described below, to allow the muddy water stored in the upper tank chamber BL1 to fall into the lower tank chamber BL2.

The bottom surface of the lower tank chamber BL2 is inclined toward the center, and an opening/closing valve _SV2 that opens only downward is provided at the bottom center of the bottom surface. In this embodiment, the opening/closing valve _SV2 functions similarly to a check valve, and as will be described later, opens and closes naturally in response to the pressure difference between the lower tank chamber BL2 and the atmospheric pressure, allowing the muddy water stored in the lower tank chamber BL2 to be discharged into the water tank W.

The mud recovery tank T according to this embodiment can perform continuous operation of sucking and discharging mud by controlling the opening and closing of the opening and closing valves _SV1 and _SV2 , but the opening and closing control of the opening and closing valves _SV1 and _SV2 can be realized by various methods. In this embodiment, as described below, the opening and closing control of the opening and closing valves _SV1 and _SV2 is performed by utilizing the air pressure difference between the upper tank chamber BL1 and the lower tank chamber BL2 and the air pressure difference between the lower tank chamber BL2 and the outside. In other words, the opening and closing valves _SV1 and _SV2 can be configured as passive valves that can be opened downwards, and no special actuator is required for opening and closing.

The communication ports C1 and C2 provided on the side surfaces of the upper tank chamber BL1 and the lower tank chamber BL2 are connected to a control valve _VL1 that can be electromagnetically controlled to open and close, and the upper tank chamber BL1 and the lower tank chamber BL2 are communicated with each other by opening the control valve _VL1 and are isolated from each other by closing it. Furthermore, the communication port C3 provided on the side surface of the lower tank chamber BL2 is connected to a control valve _VL2 that can be electromagnetically controlled to open and close, and the lower tank chamber BL2 is communicated with the outside by opening the control valve _VL2 and is isolated from the outside by closing it.

Furthermore, the upper tank chamber BL1 and the lower tank chamber BL2 are provided with level sensors S1 and S2, respectively, for detecting the muddy water levels therein. As will be described later, a valve controller (control section) 100 opens and closes control valves _VL1 and _VL2 while monitoring the water levels detected by the level sensors S1 and S2 and/or a timer, thereby executing suction/discharge control of the mud recovery tank. The suction/discharge control of the mud recovery tank will be described below.

1.2) Suction/Discharge Control The suction/discharge control of the valve controller 100 according to this embodiment will be specifically described with reference to Figures 3 and 4. The functions of the valve controller 100 can be realized by executing a program stored in a memory (not shown) on a computer processor.

3, when the vacuum suction device 14 is operated (operation 201), the valve controller 100 opens the control valve _VL1 to communicate the upper tank chamber BL1 with the lower tank chamber BL2, and closes the control valve _VL2 to isolate the lower tank chamber BL2 from the outside (operation 202). As a result, both the upper tank chamber BL1 and the lower tank chamber BL2 become negative pressure, the opening and closing valve _SV2 closes naturally, and the opening and closing valve _SV1 opens naturally, allowing the muddy water to fall into the lower tank chamber BL2 and accumulate there (FIG. 4(A)).

Next, the valve controller 100 closes the control valves _VL1 and _VL2 (operation 203). This creates a negative pressure in the upper tank chamber BL1, causing the opening/closing valve _SV1 to close naturally, and the muddy water is sucked into the upper tank chamber BL1 and stored there (FIG. 4B).

The valve controller 100 monitors whether the water level of the upper tank chamber BL1 detected by the level sensor S1 has reached a predetermined threshold value _LH (operation 204). The predetermined threshold value _LH corresponds to, for example, a water level of 80% of the tank chamber capacity. As another monitoring method, the valve controller 100 may measure the elapsed time from closing the control valves _VL1 and _VL2 using a timer and determine whether the timer has reached a predetermined elapsed time Tsuc and whether the water level of the upper tank chamber BL1 has reached a predetermined threshold value _LH . The elapsed time Tsuc may be an average value of the actual measured time from when the water level of the tank chamber reaches from zero (0% of the tank chamber capacity) to an upper limit value (for example, 80% of the tank chamber capacity). If either the water level of the upper tank chamber BL1 has reached the predetermined threshold value _LH or the timer has reached the predetermined elapsed time Tsuc, it can be determined that the water level of the upper tank chamber BL1 has reached the predetermined threshold value _LH .

When the water level of the upper tank chamber BL1 reaches a predetermined threshold value _LH (NO in operation 204), the valve controller 100 closes the control valve _VL1 and opens the control valve _VL2 (operation 205). Closing the control valve _VL1 separates the lower tank chamber BL2 from the upper tank chamber BL1, and opening the control valve _VL2 connects the lower tank chamber BL2 to the outside and increases the pressure to atmospheric pressure. This causes the opening and closing valve _SV2 to open naturally, and the muddy water stored in the lower tank chamber BL2 is discharged into the water tank W (FIG. 4(C)).

The valve controller 100 monitors whether the water level in the lower tank chamber BL2 detected by the level sensor S2 has reached zero, i.e., whether the discharge is complete (operation 206). Note that the determination of whether the discharge is complete may be made in combination with monitoring the elapsed time using a timer.

If drainage is complete (YES in operation 206), the valve controller 100 closes the control valves _VL1 and _VL2 (FIG. 4(D)). If control is not complete (NO in operation 208), the above-described operations 202 to 208 can be repeated to repeatedly execute the suction/drain cycle shown in FIGS. 4(A) to 4(D).

As shown in Figure 5, the upper tank chamber BL1 continues the suction operation throughout Figure 4 (A) to Figure 4 (D), and the lower tank chamber BL2 stores muddy water in Figure 4 (A) to Figure 4 (B) and discharges the muddy water in Figure 4 (C) to Figure 4 (D). Of one cycle from time t1 to t3, the discharge process is from time t2 to t3, and the time required for the discharge process (discharge process time) is shorter than the time required for the suction process (suction process time); for example, the suction process time = 50 seconds and the discharge process time = 5 seconds.

1.3) Recovery Tank System As illustrated in FIG. 6, the recovery tank system 12 according to this embodiment comprises mud recovery tanks T1 and T2 arranged in parallel, each of which has the structure shown in FIG. 2 and operates in the suction/discharge cycle shown in FIGS. 3 to 5.

In the following, in order to avoid repetition of explanation, the following reference symbols will be used in Fig. 6. The upper tank chamber BL1, the lower tank chamber BL2, the opening/closing valve _SV1 , the opening/closing valve _SV2 , the control valve _VL1 and the control valve _VL2 of the mud recovery tank T shown in Fig. 2 correspond to the upper tank chamber BL1x, the lower tank chamber BL2x, the opening/closing valve _SV1x , the opening/closing valve _SV2x , the control valve _VL1x and the control valve _VL2x of the mud recovery tank Tx (x = 1 or 2), respectively. For example, the control valve _VL1 of the mud recovery tank T1 and the control valve _VL11 of the mud recovery tank T2 in Fig. 6 correspond to the control valve VL1 of the mud recovery tank T in Fig. ₂ , respectively. Since the configurations and functions of these corresponding members are basically similar, detailed structures will be omitted.

Although the level sensors S1 and S2 are not shown in Fig. 6, they are provided in the same manner as in Fig. 2. Therefore, the valve controller 100 monitors the water levels in the upper and lower tank chambers of the mud recovery tanks T1 and T2, while controlling the opening and closing of the control valves _VL11 and _VL21 of the mud recovery tank T1 and the control valves _VL12 and _VL22 of the mud recovery tank T2, and executes suction/discharge control of the mud recovery tanks T1 and T2 at the timing described below.

As shown in FIG. 7, the valve controller 100 independently controls the suction/discharge operations of the mud recovery tanks T1 and T2, starting a mud suction/discharge cycle similar to that of FIG. 5 from time t1 for mud recovery tank T1, and starting a similar mud suction/discharge cycle for mud recovery tank T2 from time t2, a predetermined time td behind time t1. This delay time td is set to a time longer than the discharge process time of the mud recovery tank (t3-t4 or t5-t6). In this way, the valve controller 100 makes it possible to operate the mud recovery tanks T1 and T2 continuously so that the timing of the discharge process differs over time.

For example, as shown in FIG. 6, the suction/discharge cycle can be set so that when mud recovery tank T1 is in the suction state shown in FIG. 4(A), mud recovery tank T2 is in the discharge process shown in FIG. 4(C).

1.4) Effects As described above, according to the first embodiment of the present invention, when a pair of mud recovery tanks T1 and T2 are operated continuously, the suction/discharge processes of one of the recovery tanks T1 and T2 can be delayed by a predetermined time compared to the other, so that the suction/discharge processes of the mud recovery tanks T1 and T2 can be carried out continuously in parallel, thereby making the recovery of sedimentary soil more efficient.

2. Second embodiment The present invention is not limited to the continuous operation of the pair of recovery tanks T1 and T2 described above, but can be similarly applied to continuous operation using multiple (three or more) recovery tanks. As the second embodiment of the present invention, the continuous operation of two pairs of recovery tanks T1 to T4 will be described below. However, the same reference numbers or symbols are used for members having the same functions as those in the first embodiment, and descriptions thereof will be omitted.

To avoid duplication of explanation, the following reference symbols are used in Fig. 8. That is, as in Fig. 6, the upper tank chamber BL1, the lower tank chamber BL2, the opening/closing valve _SV1 , the opening/closing valve _SV2 , the control valve _VL1 and the control valve _VL2 of the mud recovery tank T shown in Fig. 2 correspond to the upper tank chamber BL1x, the lower tank chamber BL2x, the opening/closing valve _SV1x , the opening/closing valve _SV2x , the control valve _VL1x and the control valve _VL2x of the mud recovery tank Tx (x=1, 2, 3 or 4), respectively. Similarly, level sensors S1 and S2 are provided in each of the mud recovery tanks T1 to T4.

8, the suction pipe 121 connected to the vacuum suction pipe 23 branches into four, with the first branch connected to the suction port _I1 of the mud recovery tank T1 via a control valve _VL10 , the second branch connected to the suction port _I2 of the mud recovery tank T2 via a control valve _VL20 , the third branch connected to the suction port _I3 of the mud recovery tank T3 via a control valve _VL30 , and the fourth branch connected to the suction port _I4 of the mud recovery tank T4 via a control valve _VL40 . The exhaust port _E1 of the mud recovery tank T1 is connected to an exhaust pipe 122 connected to the vacuum suction device 14 side, and similarly, the exhaust ports _E2 to _E4 of the mud recovery tanks T2 to T4 are also connected to the exhaust pipe 122.

Although not shown in Figure 8, the recovery tank system 12a is provided with a valve controller 100 similar to that in Figure 2, which monitors the water levels in the upper and lower tank chambers of each of the mud recovery tanks T1 to T4 and controls the opening and closing of the control valves _VL11 , _VL21 , _VL12 and _VL22 of the mud recovery tanks T1 and T2 and the control valves _VL13 , _VL23 , _VL14 and _VL24 of the mud recovery tanks T3 and T4, and performs suction/discharge control of the mud recovery tanks T1 to T4 at the same timing as in Figure 7.

For example, the valve controller 100 independently controls the suction/discharge operations of the mud recovery tanks T1-T4, and delays the mud suction/discharge cycles of the mud recovery tanks T1-T4 by a predetermined time td while continuously operating the mud recovery tanks T1-T4 so that the timing of the discharge process differs over time. Alternatively, as shown in FIG. 6, the suction/discharge cycle may be set so that the mud recovery tanks T2/T4 are in the discharge process shown in FIG. 4(C) when the mud recovery tanks T1/T3 are in the suction state shown in FIG. 4(A), and the suction/discharge cycle may be set so that the mud recovery tanks T2/T4 are in the discharge process shown in FIG. 4(C) when the mud recovery tanks T1/T3 are in the suction state shown in FIG. 4(A).

Furthermore, the valve controller 100 can determine which combination of mud recovery tanks is to be operated continuously by controlling the opening and closing of the control valves VL ₁₀ , VL ₂₀ , VL ₃₀ and VL ₄₀ independently.

As described above, according to the second embodiment of the present invention, the suction/discharge processes of multiple recovery tanks can be performed continuously without overlapping in time, making it possible to efficiently recover sedimentary soil.

The present invention is not limited to two or four collection tanks as described above, but can be similarly applied to parallel continuous operation of any number of collection tanks. In other words, by setting the delay time td in the same way as the setting of the absorption/discharge timing shown in Figure 7, any number of collection tanks can be operated in parallel continuous operation.

10: Barge 11: Gate-type equipment 12: Recovery tank system 13: Filter 14: Vacuum suction device 15: High-concentration transport pump 16: Wire rope 20: Sediment 21: Agitation high-concentration pump 22: Auger-equipped suction machine 23: Vacuum suction pipe 24: Pumping transport pipe 121: Suction pipe 122: Exhaust pipe 100: Valve controller T1, T2, T3, T4: Recovery tank BL1, BL11-BL14: Upper tank chamber BL2, BL21-BL24: Lower tank chamber S1, S2: Level sensors _VL1 - _VL2 , _VL11 - _VL14 , _VL21 - _VL24 : Control valves _SV1 , _SV2 , _SV11 - _SV14 , _SV21 - _SV24: Opening and closing valve

Claims (6)

A recovery tank system having a recovery tank that sucks up and discharges muddy water containing sedimentary soil at the bottom of the water,
The recovery tank has a first tank chamber that draws in the muddy water by creating a negative pressure therein;
a second tank chamber connected to the bottom of the first tank chamber through a first opening/closing valve and having a second opening/closing valve for discharging muddy water to the bottom;
a first control valve for connecting or isolating the first tank chamber and the second tank chamber;
a second control valve for connecting or isolating the second tank chamber to or from the outside;
a valve controller that controls the opening and closing of the first and second control valves, respectively;
Equipped with
a) opening the first opening/closing valve to allow the muddy water sucked and stored in the first tank chamber to fall into the second tank chamber and be stored in the second tank chamber;
b) closing the first opening/closing valve to store the muddy water sucked into the first tank chamber;
c) opening the second opening/closing valve to discharge the muddy water stored in the second tank chamber;
d) closing the second opening/closing valve;
By repeating steps a) to d), continuous operation of the recovery tank is performed;
The valve controller controls the opening and closing of the first and second control valves, respectively, to change the air pressure in the first tank chamber and the second tank chamber, thereby carrying out a) to d) . The recovery tank system described in claim 1, characterized in that the first opening/closing valve and the second opening/closing valve are valves that open downward to allow muddy water to fall, and a) to d) are carried out by changing the air pressure in the first tank chamber and the second tank chamber. 3. The recovery tank system according to claim 1 , wherein the recovery tank is configured to have a plurality of recovery tanks arranged in parallel, and the repeating steps of a) to d) of each recovery tank are delayed in time. A method for operating a recovery tank system having a recovery tank that sucks up and discharges muddy water containing sedimentary soil at the bottom of a body of water, comprising:
the recovery tank comprises a first tank chamber which sucks in the muddy water by creating a negative pressure inside the first tank chamber, a second tank chamber which is connected to the bottom of the first tank chamber through a first opening/closing valve and has a second opening/closing valve for discharging the muddy water to the bottom, a first control valve for connecting or separating the first tank chamber and the second tank chamber, and a second control valve for connecting or separating the second tank chamber and the outside ,
The valve controller
a) opening the first opening/closing valve downward to allow the muddy water that has been sucked into and stored in the first tank chamber to fall into the second tank chamber and be stored in the second tank chamber;
b) closing the first opening/closing valve to store the muddy water sucked into the first tank chamber;
c) opening the second opening/closing valve downward to discharge the muddy water stored in the second tank chamber;
d) closing the second opening/closing valve;
By repeating steps a) to d), continuous operation of the recovery tank is performed;
By controlling the opening and closing of the first and second control valves, respectively, the air pressure in the first tank chamber and the second tank chamber are changed, thereby carrying out the above-mentioned a) to d).
A method for operating a recovery tank system. The first opening/closing valve and the second opening/closing valve are valves that open downward to allow muddy water to fall,
5. The method of claim 4 , wherein the valve controller performs a) to d) by varying the air pressure in the first tank chamber and the second tank chamber. A configuration in which a plurality of the recovery tanks are arranged in parallel,
6. The method of claim 4 or 5 , wherein the valve controller delays the repeating steps a) to d) for each recovery tank in time.

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