TW202424313A - Sediment agitating method, agitating device and use thereof - Google Patents

Abstract

A method and apparatus for agitating sediment. The method comprises suspending an agitating device (200) from a vehicle. The agitating device (200) comprising a chassis (210), first agitating apparatus (220) comprising a fluid injector conduits (330) and at least one injector pump (300). The agitating device (200) further comprises second agitating apparatus (230), comprising an inlet (310), one or more outlet (320) and at least one extractor pump (350). The method comprises suspending the agitating device (200) above, but not in contact with a waterbed having a sediment layer, agitating the sediment with the first agitating apparatus (220), extracting the sediment with the second agitating apparatus (230) and reinjecting the extracted sediment back into the waterbed with the second agitating apparatus (230).

Description

Sediment stirring method, stirring device and use thereof

The present invention relates to a method for stirring sediment, an apparatus for stirring sediment and a use thereof.

Bed evolution involves the movement of sediment in a waterway and includes the deposition of sediment on the waterbed. In these waterways there may be ports and the accumulation of sediment can cause problems as the sediment can raise the level of the waterbed and hinder shipping. In particular, the sediment can have a high shear strength which can hinder the keel of a ship passing through the sediment.

Ports are usually deeper than the surrounding waterways, and sediments tend to collect in deeper areas. Ports located on rivers are particularly affected by sediments carried downstream, and if the river is tidal, sediments carried into the port from the sea can have a further impact.

Dredging is a method by which sediment can be removed. Dredging is generally defined as the removal of sediment underwater and its transport from one place to another. Dredging is a process that may include the steps of bringing sediment up from the surface of the water bed, and optionally the steps of transporting the sediment away from the area being dredged, and finally the step of disposing of the sediment. Optionally, the sediment may be loosened first.

Examples of prior art methods of dredging include surface mounted grabs or backhoes which can be used to physically lift the sediment in a bucket whereupon the sediment is then placed into a hopper for subsequent disposal. Another prior art method is to utilize a trailing suction hopper dredger which includes a vessel connected to a towing tractor where the sediment is pumped from the water bed to a hopper on the vessel by the tractor. Alternatively, an underwater plow may be used to level the water level of the water bed.

Other prior art methods of dredging include the use of water injectors, which inject water into the sediment to loosen it and reduce the density of the sediment, causing it to float above the water bed in the form of a so-called "density cloud". The suspended sediment is then washed away by gravity. This method is particularly useful in rivers, where the resulting sediment density cloud can flow to deeper areas under the action of gravity.

There are various problems associated with prior art dredging methods. For example, water injection dredging requires water to flow due to gravity in order to remove suspended sediment and is therefore of little use in coastal or tidal harbors where there is no gradient. Leveling the water bed does not remove any sediment, it simply flattens it and the sediment continues to accumulate over time. Trailing suction hopper dredgers, while generally effective in removing sediment, require specially built expensive equipment, including customized vessels with large hoppers. Such equipment is not only expensive to purchase, but also expensive to operate. Dredging using grab arms and/or backhoes is also expensive because it requires the use of specially modified vessels with hoppers to carry away the dredged sediment.

There are problems with setting up a dredger on the water bed, for example, the water bed in a harbour is rarely smooth and will contain a lot of solid debris, making such a dredger impractical and susceptible to damage. Debris commonly encountered on the water bed in harbours includes container ties, which consist of long metal rods that can fall off the containers when loading or unloading them. Container ties can cause considerable damage to the dredger and must take considerable time to repair before the dredger can be used again, which can have a huge impact on costs.

The present invention solves the problems associated with the prior art by providing a method and apparatus which is not only capable of effectively treating sediments on a range of different water beds but is also relatively inexpensive to operate.

According to the present invention, a method for stirring sediment is provided, comprising: suspending a stirring device on a vehicle, the stirring device comprising: a chassis; a first stirring device, which is used to be arranged above a sediment layer on a water bed, the first stirring device comprising a fluid injector and at least one injection pump arranged to inject fluid through the fluid injector, the first stirring device being mounted on the chassis; a second stirring device, which comprises an inlet, one or more outlets and at least one extraction pump, the inlet and the second stirring device being connected to each other; The first stirring device is connected to an extraction pump to extract the stirred sediment, and the one or more outlets are connected to the extraction pump to reinject the extracted sediment into the water bed, the second stirring device is mounted on the chassis; and a connector is used to connect the stirring device to a vehicle; the stirring device is set above the water bed having the sediment layer but not in contact with it; the sediment is stirred with the first stirring device; the sediment is extracted with the second stirring device; the extracted sediment is reinjected into the water bed with the second stirring device.

Working according to the method of the invention by stirring, extracting and then re-stirring the sediment with the extracted sediment has been found to significantly reduce the shear strength of the sediment. In a port this may mean that although the sediment level may rise so that the sediment is in contact with the keel of a ship, the reduction in shear strength allows the ship to pass freely through the sediment. Although this method may not completely eliminate the need for dredging, it means that the amount of dredging work will be greatly reduced, saving money.

By operating the agitator above the water level of the water bed, the agitator is able to avoid most debris and to traverse uneven water beds, alleviating the problems associated with many prior art devices.

In addition to the fluid injector, the stirring device can also adopt a series of different sediment stirring tools. The first stirring device also includes one or more injection pumps, wherein the injection pump injects the fluid into the sediment through the fluid injector to loosen the sediment before extraction. The fluid injector and the one or more injection pumps are mounted to the chassis. The fluid injector can be arranged toward the lower side of the stirring device. Specifically, the fluid injector may include an outlet that is positioned to discharge the fluid in a downward direction into the sediment arranged on the water bed during use. More than one fluid injector can be provided, and a row of fluid injectors can be provided. The fluid injector may include one or more conduits that carry multiple outlets or nozzles. The outlets or nozzles can be evenly spaced along the conduit. Multiple conduits may be arranged in a parallel arrangement along the width of the chassis. One or more conduits may span the entire width of the chassis. Multiple syringe pumps may be provided, with one pump being provided for each fluid injector or each plurality of fluid injectors. The injected fluid may be water or air or a combination thereof. The fluid injector may also include an inlet connected to the syringe pump and the fluid in use is drawn from the surrounding area. In use, the fluid typically comprises water. Alternatively, the fluid may be provided to the stirring device from a surface or from a vehicle.

Prior art devices for pumping fluid to stir sediment generally use high pressure injection. High pressure in the art is defined as 800-1000 kPa (8-10 bar). In contrast, the fluid injected by the dredger according to the present invention is injected at low pressure (150-200 kPa/1.5 to 2 bar) or medium pressure (400-500 kPa/4-5 bar). Low to medium pressure injection is more advantageous than high pressure injection because it requires fewer resources in terms of pump pressure and power usage, and can effectively stir a sufficient amount of sediment.

The second stirring device comprises an inlet, one or more outlets and at least one extraction pump, the inlet being connected to the extraction pump to extract the stirred sediment, and the one or more outlets being connected to the extraction pump to re-inject the extracted sediment into the water bed, and the second stirring device is mounted on the chassis. The inlet and the one or more outlets of the second stirring device can both be arranged toward the lower side of the stirring device. The inlet may include a conduit, which includes one or more openings exposed to the lower side of the stirring device, and the conduit is connected to the extraction pump. In use, the stirred sediment is sucked into the pump through the one or more openings and the conduit. The outlet may include a conduit extending from the extraction pump to the lower side of the stirring device. The conduit of the outlet can be bifurcated.

The chassis may have a generally planar, solid base, or alternatively may be in the form of an open frame, preferably with an open base. The frame may be formed of metal or plastic tubing or the like. The chassis may include side walls and an upper surface on which items such as a first stirring device and a second stirring device are disposed. The front and rear portions of the frame may be "open", which will allow heavy material and debris to pass through the stirring device which would otherwise damage the stirring device. In addition, having an open frame will reduce the resistance of the chassis as it moves through the water, thereby allowing stirring operations to be carried out at a faster speed than was possible with prior art devices.

The chassis may include opposing side panels, and one or more transverse members may be disposed between the opposing side panels. In addition, in order to provide further support, one or more mainboards may be disposed in parallel between the side panels connected to the one or more transverse members.

The one or more transverse members may include one or more of a fluid injector for the first stirring device, an inlet for the second stirring device, or an outlet for the second stirring device. If the transverse member includes a fluid injector for the first stirring device, the transverse member may include a pipe or conduit carrying the outlet or nozzle. If the transverse member includes an inlet for the second stirring device, the transverse member may include a pipe or conduit with an opening. If the transverse member includes an outlet for the second stirring device, the transverse member may include a pipe or conduit carrying one or more openings.

At least three transverse members including the fluid injector of the first stirring device and the inlet and outlet of the second stirring device can be arranged between the side plates in a parallel arrangement. More than one of each of the fluid injector of the first stirring device and the inlet and outlet of the second stirring device can be arranged.

The transverse members may be arranged in any arrangement. For example, the fluid injector of the first stirring device may be arranged at the leading edge of the first stirring device, the outlet of the second stirring device may be arranged at the trailing edge of the second stirring device, and the outlet of the second stirring device may be arranged in between. Thus, when the vehicle pulls the stirring device over the water bed, the sediment area may be stirred by the fluid injector of the first stirring device, then drawn out by the inlet of the second stirring device, and then re-injected into the same area through the outlet of the second stirring device.

One or more transverse members may also include a rigid support bar disposed toward the leading edge of the agitator. The rigid support bar may include a tapered leading edge to cut through any deposits encountered during use.

The stirring device of the present invention in use is operated above and away from the water bed, however, the chassis may be suitably strong to withstand contact with the water bed. This may occur when the stirring device is lowered into position if the water bed is uneven, or if the vehicle is a boat and the water on which the boat floats is choppy.

The chassis may include shock absorbing means to protect the mixing device from collision with a water bed and/or debris that may be encountered during use. For example, the chassis may be provided with a bumper mounted to the underside of the chassis, or alternatively may include heavy duty skids to protect the underside of the chassis. Skids may be provided under the chassis and/or side panels. The leading edges of the chassis and/or side panels may be rounded to deflect debris.

The agitator may be provided with a deflector at the front or forward end thereof to deflect debris encountered on the water bed. The deflector may be a solid shovel to deflect debris above or below and/or to the side of the dredging equipment. The deflector may be in the form of an angled grid comprising rods that allow water to pass through to ensure that the grid does not create too much resistance but prevents the entry of debris. The grid may be suitably sized so that debris such as container lashings cannot enter the dredging equipment (even if it enters at the end) but does not create too much resistance in the water. Even if the deflector is not provided at the front of the dredging equipment, the deflector may be provided on the upper surface of the dredging equipment to protect the top of the dredging equipment. The deflector may comprise a solid plate at an angle. The solid plate at an angle may be provided in front of the injection pump.

If the chassis is open, the rear end may be provided with an offset wing, which may be a deformable pad made of rubber, plastic, etc., to keep the agitated sediment inside or below the chassis to be discharged. However, if a solid object is encountered or the pressure threshold in the agitator is reached, the offset wing will deform.

The stirring device may further include an expansion compensator disposed on the vehicle, the expansion compensator maintaining the stirring device at the same water level above the water bed.

The pumps may be provided with a power supply. The power supply may be provided on the chassis or may be provided on the vehicle above. The power pack may be provided with a stirring device which may be retrofitted to an existing vehicle, or the vehicle may be adapted to include an auxiliary power unit to provide power to one or more pumps. Power may be provided to the pumps by cables on the surface. Power may be provided in the form of electricity or hydraulics.

The stirring device according to the invention can be towed across the water bed by a vehicle, such as a boat. However, in some cases, for example if the water being dredged is a canal, the vehicle can also be a land-based vehicle. Therefore, the stirring device is provided with a connector for connecting the stirring device to the vehicle. The stirring device can also include a winch pan, which can be adapted to the vehicle to raise and lower the stirring device in the water. In some embodiments, the stirring device can be equipped with its own propulsion means.

The present invention also provides a stirring device for stirring sediments above a water bed but not in contact with the water bed, the stirring device comprising: a base; a first stirring device for being arranged above a sediment layer on the water bed, the first stirring device comprising a fluid injector and at least one injection pump arranged to inject fluid through the fluid injector, the first stirring device being mounted on the base; a second stirring device, comprising an inlet, one or more outlets and at least one extraction pump, wherein the inlet is connected to the extraction pump to extract the stirred sediment, and the one or more outlets are connected to the extraction pump to re-inject the extracted sediment into the water bed, the second stirring device is mounted on the base; and a connector for connecting the stirring device to the carrier.

The dredging apparatus may be as described with respect to the method of the present invention.

The present invention also provides a use of the stirring device as described above, wherein the use includes: connecting the stirring device to a carrier with a connector; suspending the stirring device above the water bed but not in contact with it; stirring the sediment with a fluid injector of a first stirring device; extracting the stirred sediment with a second stirring device, and re-injecting the extracted sediment into the water bed with the second stirring device.

First, refer to Figure 1, which shows a flow chart of the method for stirring sediment of the present invention. In step 110, a step of suspending a stirring device on a vehicle is shown, the stirring device comprising: a chassis; a first stirring device, which is used to be arranged above the sediment layer on the water bed, the first stirring device comprising a fluid injector, and at least one injection pump arranged to inject fluid through the fluid injector, the first stirring device being mounted on the chassis. The stirring device further comprises a second stirring device, which comprises an inlet, one or more outlets and at least one extraction pump, the inlet being connected to the extraction pump to extract the stirred sediment, and the one or more outlets being connected to the extraction pump to re-inject the extracted sediment into the water bed, the second stirring device being mounted on the chassis. The stirring device further comprises a connector for connecting the stirring device to a vehicle.

In step 120, the method includes positioning a stirring device above but not in contact with a water bed having a sediment layer. In step 130, the method includes stirring the sediment with a first stirring device. In step 140, the method includes extracting the sediment with a second stirring device, and in step 150, the method includes reinjecting the extracted sediment into the water bed with the second stirring device.

2-6, there is shown a stirring apparatus, generally designated 200, comprising a chassis, generally designated 210, a first stirring device, generally designated 220, and a second stirring device, generally designated 230. The stirring apparatus 200 further includes a connector 240 for connecting the stirring apparatus to a vehicle.

The chassis 210 includes opposed side panels 250 and a series of spaced apart parallel body portions 260. The chassis 210 further includes an upper surface 270 and a base 280. The side panels 250 and the parallel body portions 260 are connected to a transverse member 290 at a leading edge of the agitator 200.

The first stirring device 220 includes two syringe pumps 300, which include an inlet 310 for sucking water from the surrounding area when in use. The outlet 320 extends from the syringe pump 300 and branches into two fluid injector conduits 330, which extend the width of the stirring device 200 and connect the side panels 250 and the parallel main body 260. As shown in Figure 2, the nozzles 340 extend from below the fluid injector conduits 330 in a spaced arrangement.

The second stirring device 230 includes an extraction pump 350 mounted on the chassis 210. The second stirring device 230 includes an inlet, generally designated 360, in communication with the pump. As best shown in Figures 4 to 6, the inlet 360 includes a conduit 370 extending the width of the stirring device 200, which is connected to the extraction pump 350 through a connecting conduit 380. Although not shown here, the conduit 370 includes a plurality of openings disposed toward the lower side of the stirring device 200. An outlet, generally designated 390, is in communication with the extraction pump 350. The outlet 390 includes a first conduit 400 extending from the extraction pump 350 and branching into two additional conduits 410, which extend to a syringe conduit 420 disposed at the rear of the stirring device 200. As best shown in FIGS. 3-6 , the syringe catheter includes a series of spaced-apart openings 430 .

In use, the stirring device is suspended from a vehicle by a connector 240 and is positioned above but not in contact with a water bed having a layer of sediment. The sediment is stirred using the first stirring device 220. The syringe pump 300 draws liquid from the surrounding area through the inlet 310 and pumps the liquid through the outlet 320 and into the fluid syringe conduit 330. Pressurized water is discharged through the nozzle 340 into the sediment to liquefy and stir it. The stirring device 200 is pulled across the water bed by the vehicle, and the second stirring device 230 first draws the stirred sediment through the opening in the conduit 370, and the drawn sediment is sucked into the connecting pipe 380 by the extraction pump 350. The extracted sediment is then discharged by the extraction pump 350 through the outlet 390. Specifically, the extracted sediment is pumped through the first pipe 400 into the two other pipes 410 and reaches the injector conduit 420, where the extracted sediment is re-injected into the sediment in the water bed through the opening 430. The second stirring of the sediment in the water bed by the first stirring device 220 and the second stirring device 230 sufficiently reduces the shear strength of the sediment so that ships passing through the water area in contact with the sediment will not be hindered by the sediment.

200: stirring device 210: chassis 220: first stirring device 230: second stirring device 240: connector 250: side panel 260: parallel main body 270: upper surface 280: base 290: transverse member 300: injection pump 310, 360: inlet 320, 390: outlet 330: fluid injection conduit 340: nozzle 350: extraction pump 370: conduit 380: connecting conduit 400: first conduit 410: two additional conduits 420: injection conduit 430: opening

In order that it may be better understood, the present invention will now be described in detail by way of example only, with reference to the following drawings.

FIG1 shows a flow chart of the method according to the present invention.

FIG. 2 shows a perspective view of a stirring device according to the present invention.

FIG. 3 shows a side view of the stirring device of FIG. 2 .

FIG. 4 shows a rear view of the stirring device of FIGS. 2 to 3 .

FIG. 5 shows a rear perspective view of the stirring device of FIGS. 2 to 4 .

FIG. 6 shows an alternative rear perspective view of the stirring device of FIGS. 2 to 5 .

110, 120, 130, 140, 150: Steps

Claims (11)

A method for stirring sediment, comprising the following steps: Suspending a stirring device on a vehicle, the stirring device comprising: A chassis; A first stirring device, which is used to be arranged above a sediment layer on a water bed, the first stirring device comprising a fluid injector, and at least one injection pump arranged to inject fluid through the fluid injector, the first stirring device being mounted on the chassis; A second stirring device, which comprises an inlet, one or more outlets, and at least one extraction pump, the inlet being connected to the extraction pump to extract the stirred sediment, and the one or more outlets being connected to the extraction pump to re-inject the extracted sediment into the water bed, the second stirring device being mounted on the chassis; and A connector for connecting to the vehicle; Placing the stirring device above but not in contact with a water bed having a sediment layer; Stirring the sediment with the first stirring device; Extracting the sediment with the second stirring device; and Re-injecting the extracted sediment into the water bed with the second stirring device. The method of claim 1, wherein the first stirring device further comprises an inlet connected to the injection pump, and wherein the fluid is sucked in from the surrounding area. A method as described in claim 1 or 2, wherein the fluid injector of the first stirring device includes one or more conduits, which carry a plurality of nozzles arranged toward the lower side of the stirring device. A method as described in any of the preceding claims, wherein the inlet and the one or more outlets of the second stirring device are both arranged toward the lower side of the stirring device. A method as claimed in any of the preceding claims, wherein the chassis includes opposing side panels, and wherein one or more transverse members are disposed between the opposing side panels. A method as described in claim 5, wherein the one or more transverse components include one or more of the fluid injector of the first stirring device, the inlet of the second stirring device, or the outlet of the second stirring device. The method as described in claim 6 comprises at least three transverse components, including the fluid injector of the first stirring device arranged in parallel between the side plates, and the inlet and the outlet of the second stirring device. A method as described in any of the preceding claims, wherein the fluid injector and/or the extraction pump are powered by a power source disposed on the vehicle. A method as described in any one of claims 1 to 7, wherein the fluid injector and/or the injection pump is powered by a power source provided on the stirring device. A stirring device, which is arranged above a water bed but not in contact with the water bed, for reducing the shear stress of the sediment, the stirring device comprising: a chassis; a first stirring device, which is used to be arranged above the sediment layer on the water bed, the first stirring device comprising a fluid injector, and at least one injection pump arranged to inject the fluid through the fluid injector, the first stirring device being mounted on the chassis; a second stirring device, which comprises an inlet, one or more outlets and at least one extraction pump, the inlet being connected to the extraction pump to extract the stirred sediment, and the one or more outlets being connected to the extraction pump to re-inject the extracted sediment into the water bed, the second stirring device being mounted on the chassis; and A connector for connecting the stirring device to a vehicle. A use of a stirring device as described in claim 10, wherein the use comprises: connecting the stirring device to the vehicle with the connector; suspending the stirring device above the water bed but not in contact with the water bed; stirring the sediment with the fluid injector of the first stirring device; and extracting the stirred sediment with the second stirring device and re-injecting the extracted sediment into the water bed with the second stirring device.