JPH08239088A - Suction dredging vessel provided with suction apparatus withwave motion compensating apparatus hung by cable - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a dredger vessel controlling a cable tensile force properly in spite of upward/downward movement of a ship following wave motion and selectively varying its sediment suction performance. SOLUTION: This dredger vessel is provided with a suction device having a wave motion compensator changing a cable length, and a cable hangs the suction device positioned in the vicinity of a water bottom 16. The suction device is provided with a suction pipe 1 surrounded by an auxiliary pipe 10 and a pipe sleeve 3. The pipe sleeve 3 is provided with a water jetting device and a plate 5 in the lower end 4, The suction device can be placed on the water bottom by means of this plate. The pipe sleeve 3 is perforated in the part above the plate, so that sediment can flow toward an upper end 13 of the suction pipe 1. By adjusting the height of the auxiliary pipe 10, the lower end 14 can be positioned within an adjustable distance range between the suction pipe 1 and the lower ends 13, 14 of the pipe sleeve 3.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a suction dredger. The dredger is equipped with a suction device equipped with a swell compensator suspended by a cable. The wave compensator is used to change the length of the cable. When the device is in use, the cable extends downwards from the ship to the suction device, which suction device is connected to the dredging ship via suction pipes near the bottom of the water and extending upwards.

[0002]

PRIOR ART Such vessels are described in NL-C-158873. In the first ship described, a suction pipe rotatably supported is used. The lower end of this suction pipe is pivotally connected to a drag nozzle that moves along the bottom of the water as the ship moves. The end of the suction pipe equipped with the drag nozzle is suspended by a cable. One end of the cable is fixed to a block connected to the suction pipe. The cable leads to a winch drum via a number of cable rollers attached to each of the block and the ship.

If the end of the cable is guided through a cable length adjusting device installed on the ship, the cable can be kept in a tensioned state even when the ship moves up and down due to wave motion. The weight of the suction pipe equipped with the drag nozzle or a part of the weight must be used to attach the drag nozzle to the bottom of the water.

Since such a suction device requires repeated movements of the ship, the suction device can be operated from the bottom at one place for a certain time.
Especially not suitable for sucking up sand.

The second described in NL-C-158873
In the example, a part of the suction pipe used is in the bottom of the water. Therefore, if water is jetted to the water bottom from a pipe arranged adjacent to the suction pipe, the suction pipe will be buried in the water bottom. The suction pipe is connected to the ship through a flexible suction pipe. In this example, a number of cable elements suspending the suction line extend through the cable length adjuster so that the cable does not have to move much through the cable rollers with the suction pipe. In order to obtain a fixed reference point for the cable length adjuster, the pipe must be placed at the bottom of the water as described above.

While this second-described device is particularly suitable for wicking from the bottom at one location for a period of time,
It is difficult to fix the pipe to the bottom. There is also the risk that a large lateral force will be applied to the pipe. Such a situation may occur especially when the suction pipe is not connected to the ship by the flexible pipe and a fixed pipe is used as in the case of a large ship.

Further, it is difficult to control the capacity of the suction device, and there is a drawback that the dredging system is easily clogged due to a sudden inflow of a large amount of earth and sand.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to solve these problems. For this reason, according to the invention, the suction device comprises a suction pipe around which a pipe sleeve is concentrically provided. In operation, the lower end of the pipe sleeve is located below the lower end of the suction pipe. Also,
The lower end of the pipe sleeve is equipped with a plate. This plate allows the suction device to be directed to a specific location on the bottom of the water. The pipe sleeve is perforated at a portion above the plate so that the mixture of sediment and water can flow through these openings towards the suction pipe. An adjustable auxiliary pipe is concentrically mounted between the suction pipe and the pipe sleeve so that the lower end of the auxiliary pipe is located with an adjustable distance between the suction pipe and the lower end of the pipe sleeve. In the gap existing between the suction pipe and the auxiliary pipe and the pipe sleeve, the pipe sleeve is provided with a water injection device for loosening and suspending the earth and sand in the vicinity of the pipe sleeve.

As described above, by using the suction device equipped with the water injection device, a suspension of earth and sand and water can be formed around the injection device and near the lower end of the suction pipe. This suspension can be easily discharged through the suction pipe without blocking the suction pipe. Since the auxiliary pipe is provided, the suction amount of the suspension and its composition can be adjusted by adjusting the height of the auxiliary pipe.

A crater is formed at the position of the pipe sleeve as the suspension is discharged. Therefore, the earth and sand may suddenly slide down toward the bottom of the crater. As a result, a large load is applied to the suction device. Since the pipe sleeve having a diameter larger than that of the suction pipe is provided, excessive force is not applied to the suction pipe. Also,
The sediment before it becomes a suspension does not suddenly flow in and block the suction pipe.

These effects are due to the provision of the auxiliary pipe. Even if the lower end of the auxiliary pipe is blocked by the inflow of earth and sand, the water can move toward the lower end of the suction pipe through the pipe sleeve. The length of the pipe sleeve is set such that the upper end of the pipe sleeve is almost always above the earth and sand. The length of the pipe sleeve is such that even if a large amount of earth and sand suddenly flows into the crater created by the suction device, it will be above it.

In order to further control the suction of the suspension, means may be provided in this space for controlling the flow of the suspension flowing from the pipe sleeve into the substantially annular space.

For this reason, according to the invention, at a distance below the lower end of the suction pipe, the annular space between the pipe sleeve and the auxiliary pipe is substantially closed by a closure means connected to the pipe sleeve. To be The pipe sleeve also comprises openings between these closing means and the lower end of the suction pipe, these openings being completely or partly closed by means connected to the auxiliary pipe.

The closing means comprises a chamber which is connected on one side to a duct for the supply of pressurized water and on the other side to a water injection device mounted on a pipe sleeve.

The flow through the annular space between the pipe sleeve and the auxiliary pipe can also be controlled using conical parts mounted on the associated pipes and facing each other. Sliding these parts together reduces the gap between them. Such a structure is not easy because the free cross-sectional area of the space is locally reduced and the flow is disturbed.

It should be taken into consideration that it is preferable to control the suction action of the suction pipe with respect to the soil that pushes toward the suction pipe because the soil may suddenly flow into the crater created by suction. . That is,
When a negative pressure is applied to the sand, a solid mass of soil is formed, and the pipe sleeve cannot be pulled out from this mass. When the auxiliary pipe is moved upward, the high opening of the pipe sleeve closed by the auxiliary pipe is opened. As a result, the lower end of the suction pipe and these openings are connected to each other, and the suction action applied to the soil below the pipe sleeve can be removed.

Furthermore, it is important to lower the pipe sleeve abruptly at the beginning of the suction process to discharge the earth and sand to obtain a soil suspension in good condition. To do this, the water injection device located near the bottom plate of the pipe sleeve is set approximately downwards, and the water injection device provided above the porous portion of the pipe sleeve is from 0 degrees to approximately 45 degrees to the horizontal.
Angled down in degrees.

The water injection device arranged near the bottom plate is
Helps to penetrate the suction device into the soil. The water injection device
Usually, high pressure water is used.

The water jetting device mounted above the porous portion is set obliquely downward, for example, in the range of an angle of 30 degrees, and serves to suspend the earth and sand during the dredging work. These water jets generally operate at lower water pressure than water jets mounted near the bottom plate.

It will be clear that any of the water jets used in these applications can be operated simultaneously or individually.

To obtain high-pressure water and low-pressure water, for example, two water pumps which can be connected in series or in parallel can be used.

Similar to the known wave compensator, the cable with the suction device suspended extends across the cable roller to the hoisting winch. Sticking out of the compensation cylinder,
A cable roller is mounted on a rod connected to one side of a piston movable in the cylinder. On the opposite side of the piston is the hydraulic medium.

According to the invention, the space in the compensating cylinder containing the hydraulic medium communicates with the space in the second cylinder in which the freely movable piston or membrane is installed. The space on the opposite side of the piston communicates with the space in which compressed gas is present, and a check valve is arranged in the connecting pipe between the compensating cylinder and the second cylinder. Check valve is
Prevents pressure medium from flowing from the compensator cylinder to the second cylinder. A bypass is installed across the check valve. The first bypass comprises an operable stop valve and the second bypass comprises a safety valve set to a predetermined high pressure.

The third bypass is provided across the two bypasses and comprises an engageable pump having an operable inlet valve for the suction line and a check valve for the outlet line.
The hydraulic medium is supplied to the compensating cylinder under elevated pressure while the second bypass valve of the hydraulic medium supplied by the pump is actuated by the operable stop valve of the first bypass when the pump is connected. To prevent the flow to the cylinder.

In a normal operating state, that is, when the swell is normal and the suction device is erected in a free state on a solid bottom, a certain amount of load is applied to the lifting cable when the ship moves upward due to the wave motion. I will join you. The piston of the compensating cylinder is pushed down and the pressure below the piston rises. In such a case, since a large force is applied to the cable, the hoisting winch can be operated so that the piston does not come to the lowermost position in the cylinder, if necessary. For example, the hoisting winch may release the cable while the braking means act on the cable to keep the cable in a predetermined tension. It is clear that the device behaves in the same way during the descent of the ship due to waves.

When it is desired to move the suction device, the hoisting winch pulls up the suction device. The stop valve of the first bypass is then operated to prevent the flow of medium from the compensator cylinder to the second cylinder through this stop valve. As a result, the piston of the compensating cylinder stops at approximately the intermediate position. However, if the load on the piston is too large, the safety valve of the second bypass opens to prevent the cable from being overloaded.

As described above, the suction device may be buried due to an undesirable phenomenon that a large amount of earth and sand flows into the bottom of the crater formed by the suction device.
When the ship moves upward due to the wave motion, the suction device is loosely pulled as described above. Since the safety valve is installed, it is possible to prevent the cable from being overloaded.

These operations are performed in stages. For example, if the suction device is pulled up by 1 m, the valve of the first bypass will be opened again and the piston of the compensator cylinder will again move to the intermediate position.

With little or no waves, it becomes difficult to pull the suction device loosely. Therefore, a pump is provided in the above-mentioned third bypass. This pump can be used to generate high pressure in the compensator cylinder. In this state, when the stop valve of the first bypass is closed again, the generated pressure is limited by the safety valve of the second bypass. Embodiments of the present invention will be described below with reference to the accompanying drawings.

[0030]

DESCRIPTION OF THE PREFERRED EMBODIMENT The suction device shown in FIG. 1 comprises a suction pipe 1 connected to a suction pipe extending to a ship. The structure is shown briefly.

The support pipe 2 is used to connect the suction pipe 1 to the pipe sleeve 3. The pipe sleeve 3 has a lower end 4 provided with a plate 5 and does not have to be completely closed.

The pipe sleeve 3 has a porous portion 6 shown by a dotted line above the plate 5. The through-holes in this part 6 of the pipe sleeve 3 can, for example, be in the form of a number of slotted holes, which are arranged at different heights or arranged in any desired arrangement.

The pipe sleeve 3 is provided with a low-pressure water injection device 7 above the porous portion 6 and a high-pressure water injection device 8 installed near the plate 5 or installed on the plate 5. The water injection device 7 is arranged downward at an angle of 30 degrees with respect to the horizontal. Water can be supplied to the water injection device 7 through a pipe (not shown). This pipe communicates with an annular chamber 9 fixedly connected to the wall of the pipe sleeve 3.

The chamber 9 encloses an auxiliary pipe 10 located between the suction pipe 1 and the pipe sleeve 3. This auxiliary pipe 10 is connected to the support 2 or the suction pipe 1 via one or more pressurized medium cylinders 11, so that this auxiliary pipe 10 can be adjusted in the longitudinal direction. In some situations, guides may be provided between each pipe.

The upper end 12 of the auxiliary pipe 10 is the suction pipe 1
Is located above the lower end 13 of the. Further, the lower end 14 is arranged above the plate 5 and is located below the chamber 9 connected to the pipe sleeve 3 during normal operation.

A plurality of openings 15 are formed in the pipe sleeve 3 above the chamber 9. These openings 15
Are almost closed by the closing plate 15a during normal operation. The closure plate is shown in simplified form and is connected to the auxiliary pipe 10. When the auxiliary pipe 10 is moved upward, the opening 15 is gradually opened. Suction pipe 1
Due to the negative pressure generated in the pipe sleeve 3, water or a soil suspension such as sand in water can be sucked into the pipe sleeve 3 through the opened opening 15. As described above, such a function is effective when the soil suddenly collapses toward the bottom of the crater on the ground and the circumference of the pipe sleeve is completely filled with the soil. If the suction action of the suction pipe acts on this collapsed soil, the soil may be compressed into a strongly compacted mass, making it impossible to pull up the suction device.

The dotted line 16 represents the ground surface during operation of the suction device. This ground surface refers to the hard part of the soil, and there is a suspension of soil particles in the water above the dotted line. The suspension is sucked and removed through the suction pipe 1.

Depending on the situation, the pipe sleeve 3 can be suspended by the cable 17 shown in FIG. 2 through the suction pipe. The suction pipe 1 can be connected to a suction pipe via a bellows, for example.

The cable 17 extends through several cable rollers 18 to a winding winch 19. One cable roller 18 is mounted on a piston rod 21 protruding from a piston 20 of a hydraulic compensator cylinder or jack 22. The space 23 of the cylinder 22 is
Freely movable piston or film 27 inside via pipe 24
Is connected to the space 25 of the second cylinder 26. The space 28 of the cylinder 26 is connected to one or more pressurized gas reservoirs 29. Nitrogen is the most commonly used gas for this reservoir.

A check valve 30 is provided in the pipe 24, and an operable stop valve 32 is attached to a first bypass 31 that straddles the check valve 30. A safety valve 34 is attached to the second bypass 33 that straddles the check valve 30.

In the third bypass 35, the bypass 31,
A pump 36 and stop valves 37 and 38 are arranged across 33. A valve 39 can be provided across the check valve 37. This valve is opened when the pump 36 is used.
Therefore, the hydraulic medium having a higher pressure than that generated by the pressurized gas from the reservoir 29 can be supplied to the space 23. The check valve 30 provided in the pipe 24 and detourable by the valve 32 is opened during normal operation.
The check valve 30 serves to prevent the pressure medium from flowing back into the space 25.

For example, in the case of a penetrating suction device, the hoisting winch 19 lowers the compensator cylinder 22 to an excessive lowermost position when the suction device is moved, that is to say in the situation where the lifting operation has to be carried out first. It is necessary to prevent These operations are performed by engaging the check valve 30 by closing the valve 32 before releasing the brake on the hoisting winch.

In this way, during the upward movement of the ship, the pressure in the space 23 of the compensator cylinder 22 is reduced by the safety valve 34.
It will increase up to the maximum value set in. This causes the suction device to be lifted by a controlled force that is greater than the force that it is constantly applying.

If the suction device has not penetrated into the soil,
Alternatively, if it is pulled out immediately, the pressure in the space 23 of the compensator cylinder 22 and in the pipe 24 drops to a normal value or is kept low. For example, when a command is issued from the time relay set to the cycle of three waves, the valve 32 opens and at the same time the winch 1
9 is canceled. Since the hoisting winch 19 performs the pulling operation and the piston rod 21 of the cylinder 22 is completely pushed down, there is no risk of overload,
The suction device can be moved upwards.

However, since the pressure in the space 23 of the cylinder and the pressure in the pipe 24 increase each time the ship moves upward if the suction device is still in the penetrating state, the time relay does not open the valve 32 and the winch 19 is not opened. Will never be released. If such an operation is performed, there is no risk of equipment damage. The required operation is every time the ship moves up
A controlled pulling force is applied to gently pull the device. The energy generated by this is
It is removed by cooling the hydraulic medium.

As the ship moves downwards, the pressure in the reservoir 29 and the spaces 28, 25 pushes the hydraulic medium back through the check valve 30 into the compensator cylinder 22.

In situations where the sea is calm and the ship does not wobble, or only slightly, the suction force is also pulled gently by the auxiliary force applied by the pump 36. This pump 36 pushes the oil from the cylinder 25 to the cylinder 22 at high pressure after closing the required valve.
Hoisting winch 19 remains braked.

Also, it should be noted that when it is necessary to raise at least a part of the suction device without using the suction device, it is possible to use a known method to keep the suction device in a horizontal posture. Is connected to the suction device. This cable also needs to be tensioned by a suitable means.

The embodiments shown in the drawings and described so far are merely exemplary embodiments of the device according to the invention. Obviously, any modifications can be made without departing from the concept of the invention.

[Brief description of drawings]

FIG. 1 is a schematic vertical sectional view of a suction device according to the present invention.

FIG. 2 is an explanatory diagram of a wave compensation device used in the present invention.

[Explanation of symbols]

 1 Suction Pipe 2 Support 3 Pipe Sleeve 5 Plate 6 Porous Part 7 Low Pressure Water Injection Device 8 High Pressure Water Injection Device 9 Chamber 10 Auxiliary Pipe 11 Pressurizing Medium Cylinder 15 Opening 17 Cable 18 Cable Roller 22 Cylinder 24 Communication Pipe 26 Second Cylinder 29 reservoir 30 check valve 31 first bypass 32 stop valve 33 second bypass 34 safety valve 35 third bypass 36 pump 37 check valve 38 check valve 39 inflow valve

Claims (9)

[Claims] 1. A suction dredger equipped with a suction device having a wave compensator suspended by a cable, said wave compensator being used to change the length of a cable (17), said cable being During use of the suction device, it extends downwards from the ship towards the suction device, which suction device is connected to the dredging vessel via a suction pipe near the bottom of the water (16) and extends upwards. Has a suction pipe (1) concentrically provided with a pipe sleeve (3), and in operation, the lower end (4) of the pipe sleeve is arranged below the lower end (13) of the suction pipe (1), and The lower end (4) is provided with a plate (5) through which the suction device can reach a given water bottom (1
6) and above the plate (5) of the pipe sleeve (3) there is a hole in the length (6) of the pipe sleeve to allow the sediment / water The mixture can flow through these openings towards the suction pipe (1) and an adjustable auxiliary pipe (10) is concentrically mounted between the suction pipe (1) and the pipe sleeve (3). , The lower end (14) of the auxiliary pipe (10) is arranged with an adjustable distance between the suction pipe (1) and the lower ends (13, 4) of the pipe sleeve (3). Pipe (1) and auxiliary pipe (10)
A space is provided between the pipe sleeve (3) and a water injection device (7, 8) for loosening and suspending the soil near the pipe sleeve (3). A suction dredger. 2. The suction dredger according to claim 1, characterized in that the length of the pipe sleeve (3) is such that the upper end of the pipe sleeve is almost always above the ground. A suction dredger. 3. The suction dredger according to claim 1 or claim 2, wherein the space between the auxiliary pipe (10) and the pipe sleeve (3) reaches the space through the pipe sleeve (3). Suction dredger, characterized in that it is equipped with means (15, 15a) for controlling the flow of the suspension. 4. A suction dredger according to claim 3, wherein the pipe sleeve (3) and the auxiliary pipe (1) are located some distance below the lower end (13) of the suction pipe (1).
The annular space between 0) is substantially closed by closing means (9) connected to the pipe sleeve and between the closing means (9) and the lower end (13) of the suction pipe (1) the pipe sleeve (9). 3) A suction dredger characterized in that it comprises an opening (15) which can be partially or completely closed by means (15a) connected to an auxiliary pipe (10). 5. The suction dredger according to claim 4, wherein the closing means has one side connected to the pressure water supply duct and the other side installed in the pipe sleeve (3). A suction dredger characterized in that it has a chamber (9) connected to it. 6. The suction dredger according to claim 1, wherein the water injection device (8) arranged near the bottom plate (5) of the pipe sleeve (3) is substantially the same. Pointed down and also pipe sleeve (3)
The water injection device (7) above the porous part (6) of
Suction dredger characterized by being downward at an angle of 0 to almost 45 degrees with respect to the horizontal. 7. A suction dredger having a wave compensator, wherein a cable (17) with the suction device suspended is wound up through a cable roller (18) to a winch (19), and the cable roller (18) is a compensator. Projecting from the device cylinder (22) and cylinder (22)
In a suction dredger, which is mounted on a rod (21) connected to one side of a piston (20) which is movable inside, a space (23) on the opposite side of the piston (20) contains a hydraulic medium. Compensator cylinder with pressure medium (22)
The inner space (23) is a freely movable piston (2
7) or the space (25) communicating with the space (25) in the second cylinder (26) in which the membrane is installed, and the space (28) opposite to the piston (27) is the space ( 29), a check valve (30) is arranged in the connecting pipe (24) between the compensator cylinder (22) and the second cylinder (26), said check valve being the compensator. Bypassing the pressure medium from the cylinder (22) to the second cylinder (26), a bypass (31, 33) is installed across this check valve, the first bypass (31) being operated. Suction dredger, characterized in that it comprises a possible stop valve (32) and that the second bypass (33) comprises a safety valve (34) set to a predetermined high pressure. 8. The suction dredger according to claim 7, wherein a third bypass (35) is installed across the two bypasses (31, 33) and is operable into the suction pipe. Check valve (38) in valve (39) and discharge pipe
A connectable pump (36) with a pump is installed to supply the hydraulic medium to the compensator cylinder (22) under high pressure while the operable stop valve (3) of the first bypass (31).
By 2), when the pump (36) is connected,
A suction dredger characterized in that a backflow of the hydraulic medium supplied to the second cylinder (26) by the pump is prevented. 9. Use with a suction dredger.
9. A suction device and a wave compensator according to one or more of claims 8 to 10.