JP7548811B2 - Dredge Pump - Google Patents

Description

The present invention relates to dredging technology for dredging sediments accumulated on the bottom of reservoirs such as dam lakes, and in particular to a dredging pump suitable for this type of application.

In a typical dam, dredging work is necessary to remove sediments such as mud, soil, boulders, gravel, and sunken wood that have accumulated at the bottom of the dam lake in order to maintain the dam's water storage capacity.
In response to this, for example, Patent Document 1 discloses a dredging device using a pump dredging method in which a dredging pump is used to suck up sediments from the bottom of the water and send out mud. The dredging device described in this document includes a dredging pump and a crusher provided at a position opposite the suction side of the dredging pump.

In particular, the dredging device described in the document uses two twin-shaft crushers arranged in two levels, one above the other, as crushers. As a result, even if the sediments contain boulders or sunken wood, the two-stage crushing process of the dredging device described in the document can more reliably crush the sediments to a size that can be sucked in and discharged by the dredging pump. This makes it possible to prevent or suppress blockage of the dredging pump.

JP 2019-178566 A

As mentioned above, the technology described in Patent Document 1 is a technology that prevents or suppresses blockages in the dredging pump in the subsequent process by making improvements in the crushing process, which is a process prior to the suction and discharge process by the dredging pump.

As a result, the dredge pump itself and the clogging potential in the sludge transport pipeline remain the same as in the past, and there is still room for improvement in providing dredging technology that can prevent or reduce clogging in the pump itself and the sludge transport pipeline in pump dredging methods.

In pump dredging, in order to avoid blockages caused by the settling of sediment in the sludge transport pipeline connected to the discharge side of the dredge pump, it is common to operate the dredge pump by keeping the sand content of the sludge liquid below a certain percentage.

On the other hand, even when using a crusher as in the technology described in Patent Document 1, if boulders or sunken wood are sucked into the casing, the impeller rotating inside the casing may become locked or blocked. Normally, when an operator determines that the impeller is locked or blocked, measures are taken to reverse the impeller to resolve the lock or blockage.

However, in pump dredging, simply driving the impeller in the reverse direction causes a backflow of sediment being discharged from the sludge transport pipeline. If this causes the sand content near the discharge side of the sludge transport pipeline to increase above a predetermined rate, it may cause a blockage of sediment in the sludge transport pipeline, making it difficult to restart the pipeline.

The present invention was made with a focus on these problems, and aims to provide a dredging pump that, when the impeller becomes locked or blocked inside the casing in a pump dredging system, reverses the impeller to resolve the lock or blockage, and also prevents or suppresses blockage of sediment in the sludge transport pipeline.

In order to solve the above problems, a dredge pump according to one aspect of the present invention is a dredge pump comprising a casing and an impeller rotatably disposed within the casing, and further comprising: a blockage detection means for detecting a locked or blocked state of the impeller; a branch pipe branched from a mud transport pipe connected to the discharge side of the casing and opening into the water; a first valve attached to the opening of the branch pipe; a second valve interposed in the mud transport pipe downstream of the branch and performing an opening/closing operation opposite to that of the first valve; and a controller for executing a blockage elimination process based on blockage information acquired from the blockage detection means, wherein the controller executes a blockage elimination control for driving the impeller in the reverse direction with the first valve open and the second valve closed when blockage information is acquired, and executes a normal control for driving the impeller in the forward direction with the first valve closed and the second valve open when blockage information is not acquired.

According to a dredge pump according to one aspect of the present invention, when a locked or blocked impeller condition is detected within the casing, the impeller can be reversed to resolve the locked or blocked condition.
Furthermore, according to the dredge pump of the present invention, when the impeller is driven in the reverse direction, the first valve is opened while the second valve is closed, so that when the impeller is driven in the reverse direction, the water taken in from the opening of the branch pipe is introduced from the middle of the mud transport pipe, while the sediment in the mud transport pipe is maintained in the position before the reverse drive.

This prevents backflow of sediment that was being discharged from the sludge transport pipeline, and smooth reverse control enables the impeller to be quickly and reliably unlocked or unblocked.
Therefore, according to one aspect of the dredge pump of the present invention, when the impeller becomes locked or blocked within the casing, the impeller can be reversed to relieve the impeller lock or blockage within the casing, while also preventing or suppressing blockage of sediment within the mud transport pipeline.

As described above, according to the present invention, when the impeller becomes locked or blocked inside the casing, the impeller can be reversed to eliminate the lock or blockage of the impeller inside the casing, and the blockage of sediment in the sludge transport pipeline can also be prevented or suppressed.

FIG. 1 is a schematic diagram illustrating an embodiment of a dredging system using a dredging pump according to one aspect of the present invention. This is an explanatory diagram of one embodiment of a dredge pump relating to one aspect of the present invention, in which the pump main body is shown in a longitudinal cross section along the axis, and the configuration related to the blockage detection means is shown diagrammatically attached to the pump main body. 13 is a flowchart of a blockage resolution process executed by a management computer (controller) in the embodiment shown in FIG. 1 .

Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Note that the drawings are schematic. Therefore, it should be noted that the relationship and ratio between thickness and planar dimensions are different from the actual ones, and the drawings include parts where the relationship and ratio of dimensions are different from each other.
Furthermore, the embodiments described below are merely examples of devices and methods for embodying the technical ideas of the present invention, and the technical ideas of the present invention do not limit the materials, shapes, structures, arrangements, etc. of the components to the embodiments described below.

FIG. 1 shows a dredging system including a dredging pump 10 of this embodiment.
As shown in the figure, this dredging system is composed of a surface base 50 placed on a water-borne steam locomotive such as a dam lake, and a dredging device 100 suspended from the surface base 50 by a wire 57 and deployed on the water bottom.

The surface base 50 is equipped with a generator 51, a work machine 54 including a winch, a variable displacement hydraulic pump 55 driven by an internal combustion engine as a hydraulic power source, and a management computer 30 that constitutes a controller. The management computer 30, the generator 51, and the hydraulic pump 55 are connected to a dredging device 100 placed on the lake bottom SB of the dam lake via an umbilical cable 56.

The dredging device 100 can receive the power and control signals necessary for operating the dredging device 100, as well as pressure oil, from the surface base 50 via an umbilical cable 56. The dredging device 100 of this embodiment includes a dredging tower 53 that can be erected on the lake bottom SB of the dam lake, and a dredging pump 10 installed in the center of the dredging tower 53. The dredging pump 10 of this embodiment uses a submersible sand pump, enabling pump dredging in which excavated sediments are sent to the mud transport hose 7 together with muddy water.

More specifically, the dredge pump 10 of this embodiment includes a pump drive unit 3 and a casing 1 provided below the pump drive unit 3, as shown in FIG. 2. The casing 1 has a suction port 1s on the bottom surface, and a suction hopper (not shown) is attached to the suction port 1s. When configuring a dredging device using the dredging pump 10 of this embodiment, a crusher can be provided in the suction hopper portion on the suction port 1s side of the dredge pump 10. In the example shown in the figure, a multi-hole pipe type strainer 15 is attached.

The pump drive unit 3 has a built-in submersible motor 5. A captive cable 52 is connected from a control unit 6 to the top of the pump drive unit 3, and power supplied from a generator 51 installed on a water base 50 on the lake is supplied from the captive cable 52 to the submersible motor 5 via the control unit 6. The captive cable 52 is installed inside the umbilical cable 56 in Figure 1.

The drive shaft 8 of the submersible motor 5 is rotatably supported at the top and bottom by bearings 9A and 9B, and the lower end of the drive shaft 8 protrudes downward from the center of the upper part of the casing 1. An impeller 2 is coaxially attached to the tip of the drive shaft 8 inside the casing 1. A shaft seal 4 such as a mechanical seal or oil seal is provided between the pump drive unit 3 and the casing 1 around the drive shaft 8 of the submersible motor 5.

A discharge port 1t is provided on the side of the casing 1, and a mud transport pipeline 13 is connected to the discharge port 1t. The mud transport pipeline 13 is connected to a flexible mud transport hose 7 that is extended along the lake bottom. As a result, in the dredge pump 10 of this embodiment, when the submersible motor 5 is driven, the impeller 2 is driven in a predetermined direction to generate a vortex inside the casing 1, and mud water is sucked in together with the crushed dredged material from the suction hopper facing the lake bottom according to the pump discharge volume, and can be discharged from the suction port 1s to the mud transport hose 7 via the mud transport pipeline 13.

In the dredge pump 10 of this embodiment, an elbow is interposed at the connection between the mud transport pipeline 13 and the mud transport hose 7 to provide a branch pipeline 14. As a result, the branch pipeline 14 branches off from the mud transport pipeline 13 connected to the discharge side of the casing 1 and opens into the water.
In the dredge pump 10 of this embodiment, a first check valve 11 serving as a first valve is attached to the opening of the branch pipeline 14. In the figure, a strainer 16 made of round steel bars arranged in a mesh is attached to the suction side opening of the first check valve 11. Furthermore, a second check valve 12 serving as a second valve is attached to the mud transport pipeline 13 at a position downstream of the branch of the branch pipeline 14.

The first check valve 11 in this embodiment is a check valve that automatically closes if the fluid attempts to flow in the reverse direction, with the forward direction being from the opening side of the branch pipeline 14 toward the casing 1 side. On the other hand, the second check valve 12 in this embodiment is a check valve that automatically closes if the fluid attempts to flow in the reverse direction, with the forward direction being from the casing 1 side toward the mud transport pipeline 13 side.

In addition, in the dredge pump 10 of this embodiment, pressure detection sensors 40A, 40B are attached to the suction port 1s and discharge port 1t of the casing 1, respectively, as blockage detection means for detecting whether the impeller is locked or blocked. The management computer 30 monitors the transport status of the dredged material and executes a blockage elimination process to prevent or suppress blockage, and when it determines that a blockage has occurred, executes blockage elimination control to drive the impeller 2 in the reverse direction to perform reverse drainage.

In more detail, the management computer 30 includes a central processing unit (CPU) (not shown) and memory units such as a RAM (random access memory) and a ROM (read only memory) connected to the CPU, as well as input/output devices. The memory unit stores a number of drive patterns that prestore torque information required for draining water by the dredge pump 10 according to the type of dredged material (e.g. boulders, sunken wood, etc.).

The management computer 30 selects the drive pattern of the dredging pump 10 according to the condition of the dredged material based on the pressure detection sensors 40A, 40B and current information obtained from a circuit for constant horsepower control of the underwater motor 5, making it possible to perform appropriate control using, for example, a regulator.

The blockage elimination process is a timer interrupt process to the normal control process that drives the impeller 2 in the forward direction. When the blockage elimination process is executed, the management computer 30 proceeds to step S10 as shown in FIG. 3 and monitors whether blockage information has been acquired.

In this embodiment, the blockage information is obtained by comparing the pressure information from the pressure detection sensors 40A and 40B and the current information from the underwater motor 5 with a preset threshold value. If the blockage information is obtained under the monitoring by the management computer 30, the process proceeds to step S20, otherwise the process proceeds to step S30.

In this embodiment, the blockage information acquired from the blockage detection means is pressure information, with the measured values from the pressure detection sensors 40A and 40B being treated as pressure information, and arbitrary threshold values being set for these measured values, while the current value of the submersible motor 5 at the virtual operating point is monitored and an arbitrary threshold value is also set for this current value. The management computer 30 is configured to determine that blockage information has been acquired when these values exceed a preset lower limit or upper limit, and to determine that a blockage has occurred in the dredge pump 10.

More specifically, for example, if the water depth of the lake bottom SB of the dam lake is 5 m and the total pump head of the dredge pump 10 is 15 m (the liquid specific gravity is 1), then during normal operation, the pressure information of the pressure detection sensor 40A at the suction port 1s is 5 m, the pressure information of the pressure detection sensor 40B at the discharge port 1t is 20 m, and the current value of the underwater motor 5 at the virtual operating point is 50 A, which are each sent to the management computer 30 as measured values (however, the pressure units are water columns m).

In response to this, the above thresholds are set in advance to, for example, 2 m for the pressure information at the suction port 1s, 10 m for the pressure information at the discharge port 1t, and 30 A for the current value of the underwater motor 5 at the virtual operating point. Therefore, since all of the above measured values are determined to be within the normal value range, the management computer 30 determines that the operating state is normal and normal operation continues.

As an example of a blocked state, the pressure information from the pressure detection sensor 40A at the suction port 1s is 1m, the pressure information from the pressure detection sensor 40B at the discharge port 1t is 5m, and the current value of the underwater motor 5 at the virtual operating point is 20A. These are the respective measured values sent to the management computer 30.

The management computer 30 compares the acquired measurement value with the above threshold value, and in this example, since the pressure information 1m at the suction port 1s, the pressure information 5m at the suction port 1s, and the current value 20A of the underwater motor 5 at the virtual operating point are all smaller than the predetermined threshold value, it determines that a pressure drop has occurred simultaneously and that blockage information has been acquired. As a result, in step S20, the management computer 30 executes blockage elimination control to drive the impeller in the reverse direction, and then returns to the process in step S10. In step S30, it continues normal control to drive the impeller in the forward direction, and returns to the process.

As a result, when blockage information is acquired, the management computer 30 is able to execute blockage elimination control in which the impeller 2 is driven in the reverse direction with the first check valve 11 open and the second check valve 12 closed.
In addition, when no blockage information is acquired, the management computer 30 is capable of executing normal control in which the impeller 2 is driven in the forward direction with the first check valve 11 closed and the second check valve 12 open.

Next, the procedure for dredging sediments from the bottom of a dam lake using the dredging device 100 equipped with the above-mentioned dredge pump 10, as well as the action and effect of this dredge pump 10 will be described.
First, as shown in Fig. 1, the surface base 50 with the dredging equipment 100 suspended therefrom is anchored at a desired position on the lake. Next, the wire 57 is paid out using the working machine 54 installed on the surface base 50, the dredging equipment 100 is lowered into the water, and the dredging tower 53 is installed at an appropriate position on the bottom of the dam lake so that the dredging equipment 100 is positioned as desired.

After the dredging device 100 is installed, a crusher (not shown) and the dredging pump 10 are driven. When the dredging device 100 is driven, the crusher crushes the dredged material and sends the dredged material toward the dredging pump 10 above.
The dredging pump 10 sucks up the excavated sediments together with the muddy water, and moves the dredging device 100 from its installation position S to a relocation position M on the water via a mud-transport hose 7 disposed underwater, for example, as shown in Fig. 1. By moving the water base 50 with the dredging device 100 suspended therefrom, dredging of sediments can be continued on the bottom of the dam lake.

Here, in pump dredging based on the performance of the dredge pump 10, if the dredge pump 10 is not properly controlled, the proportion of soil and sand containing the crushed dredged material (sand content) will increase, and if the pumping distance of the mud transport hose 7 becomes long, the mud transport pipeline 13 and the mud transport hose 7 may become clogged, making it impossible to transport the crushed dredged material stably.

In pump dredging, a common method is to operate a dredging pump 10, such as a submersible pump, by suppressing the sand content of the slurry liquid to a predetermined percentage or less in order to avoid sedimentation in the piping.
In contrast, in the dredging equipment 100 of this embodiment, when no blockage information is obtained based on the pressure detection sensors 40A, 40B and current information obtained from circuits for constant horsepower control of the underwater motor 5, the management computer 30 executes normal control to drive the impeller 2 in the forward direction with the first check valve 11 closed and the second check valve 12 open.

In normal control, the management computer 30 selects the drive pattern of the dredge pump 10 according to the condition of the dredged material, and increases or decreases the suction flow rate of the dredge pump 10, for example using a regulator, so as to keep the sand content of the pumped liquid below a predetermined value.

As a result, the dredging device 100 of this embodiment can continue normal control to drive the impeller in the forward direction while more effectively preventing or suppressing clogging of the dredge pump 10. Therefore, the dredging device 100 of this embodiment is suitable for avoiding sedimentation of sediment in the mud transport pipeline 13 and the mud transport hose 7 by suppressing the sand content in the slurry liquid pumped by the dredge pump 10 to a predetermined value or less.

Here, depending on the nature of the dredged material, such as boulders and sunken wood, there is a risk of blockage occurring in the dredging pump 10. In response to this, in the dredging pump 10 of this embodiment, the management computer 30 executes a blockage elimination process, monitors the transport status of the dredged material, and when it determines that a blockage has occurred, executes blockage elimination control that reverses the impeller in cooperation with the opening and closing operations of the two check valves 11 and 12. Therefore, when the impeller becomes locked or blocked, the lock or blockage of the impeller can be quickly eliminated, and also the blockage of sediment in the sludge transport pipeline can be prevented or suppressed.

In other words, dredging pumps are used to remove sediment that accumulates on the bottom of dams and lakes, and driftwood and other debris are found on the bottom of the lake. Therefore, if these are sucked into the impeller 2, the impeller 2 may lock or the casing 1 may become clogged. Conventionally, when a lock or blockage occurs in the impeller, the impeller is reversed to resolve the problem.

However, as mentioned above, in pump dredging, simply driving the impeller in reverse will cause a backflow of sediment being discharged in the mud transport hose 7 and the mud transport pipeline 13. If this causes the sand content near the discharge side of the mud transport pipeline 13 to increase above a predetermined rate, there is a risk that sediment will be blocked in the mud transport pipeline 13, making it difficult to restart the system.

In contrast, in the dredge pump 10 of this embodiment, the management computer 30 monitors the pressure detection sensor 40A provided in the suction section, the pressure detection sensor 40B provided in the discharge section, and the drive current value of the submersible motor 5. When the management computer 30 determines that a locked or blocked state has occurred, it executes blockage elimination control, allowing for quick and reliable unlocking through smooth reverse control. This makes it possible to prevent or suppress blockage of the dredge pump 10.

In particular, in the dredge pump 10 of this embodiment, as described above, a first check valve 11 is interposed in the mud transport pipeline 13 on the discharge side, which can prevent backflow of dredged soil from the discharge port side during reverse control. The return flow path during reverse control is branched off from the mud transport pipeline 13 by a branch pipeline 14, and the branch pipeline 14 is equipped with a second check valve 12 that operates in the opposite direction to the first check valve 11.

Therefore, during blockage removal control, blockage removal control can be executed by driving the impeller 2 in the reverse direction with the first check valve 11 open and the second check valve 12 closed. As a result, according to the dredge pump 10 of this embodiment, when the impeller 2 is driven in the reverse direction, water taken from the opening of the branch pipe 14 is introduced from the middle of the mud transport pipe 13, while the mud transport hose 7 and the sediment in the mud transport pipe 13 are maintained in the position they were in before the reverse drive.

Therefore, according to the dredge pump 10 of this embodiment, the impeller 2 can be reversed to eliminate locking or blockage of the impeller 2 within the casing 1, and blockage of sediment within the mud transport pipeline 13 can also be prevented or suppressed.
Furthermore, the dredge pump according to the present invention is not limited to the above-described embodiment, and it goes without saying that various modifications are possible without departing from the spirit of the present invention.

For example, in the above embodiment, check valves 11 and 12 are provided in the mud transport pipeline 13 and the branch pipeline 14, respectively. However, this is not limiting. Instead of check valves, electromagnetic valves, for example, may be provided in each pipeline, and the electromagnetic valves may be controlled to open and close by the management computer 30 (controller).

REFERENCE SIGNS LIST 1 Casing 2 Impeller 3 Pump drive section 4 Shaft seal section 5 Submersible motor 6 Control unit 7 Mud transport hose 8 Drive shaft 9A, 9B Bearings 10 Dredge pump 11 First check valve (first valve)
12 Second check valve (second valve)
13 mud transport pipeline 14 branch pipeline 15 strainer 16 strainer 30 management computer (controller)
40A, 40B Pressure sensor (obstruction detection means)
50 Surface base 51 Generator 52 Captive cable 53 Dredge tower 54 Work machine 55 Hydraulic pump 56 Umbilical cable 57 Wire 100 Dredge equipment

Claims (2)

A dredge pump comprising a casing and an impeller rotatably disposed within the casing,
a blockage detection means for detecting a locked or blocked state of the impeller;
A branch pipe that branches off from a mud transport pipe connected to a discharge side of the casing and opens into water;
a first valve attached to an opening of the branch line;
A second valve is disposed in the mud transport pipeline downstream of the branching portion and performs opening and closing operations in a direction opposite to that of the first valve ;
a controller that executes a blockage resolution process based on the blockage information acquired from the blockage detection means;
The controller:
When the blockage information is acquired, a blockage elimination control is executed to drive the impeller in a reverse direction while the first valve is opened and the second valve is closed.
when no blockage information is acquired, a normal control is executed to drive the impeller in a normal direction with the first valve closed and the second valve open.
A dredge pump characterized by: The dredge pump of claim 1, wherein the first valve and the second valve are check valves.

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