ES2319781T3 - DRAGING HEAD FOR A DRILLING HOPPER DRIVING AND PROCEDURE TO DRAG USING SUCH DRAGING HEAD. - Google Patents

Abstract

This invention concerns a drag head for a trailing suction hopper dredger which essentially consists of a structure connected to a suction pipe, with a visor (2) rotating around an horizontal axis (6), in which a series of teeth (10) are applied for breaking up the sand, which are arranged along a line which extends perpendicularly with respect to the direction of motion of the drag head, and a first series of jet pipes (9) for injecting water under high pressure, which are arranged along a line parallel to the line and in front of said teeth, wherein at least one second series of jet pipes (12,12') is provided along a line parallel to and behind the line of said teeth Figure 1.

Description

Dredging head for a hopper dredger towed aspirant and procedure to dredge using said dredging head

The invention refers to a head of dredging for a towed hopper dredger, which essentially consists of a structure connected to a tube of suction, with a protective visor that rotates around an axis horizontal, in which there are a series of teeth to break the sand, being provided with a serrated arm that extends perpendicularly with respect to the direction of movement of the head dredging, and a series of nozzle tubes to inject water into pressure, extending parallel to said toothed arm and in front of said teeth, always considering the direction of movement of the dredging head

Said dredging head according to the preamble of claim 1 is known from the patent
GB-A-1,312,032. In GB-A-1.312.032, an aspirating hopper dredger is described that solves the problem of providing means that allow a greater part of coherent soil to be carried by the scraper of the aspirating hopper dredger in the current aspiration. This is achieved by increasing the available suction pressure to lift the water and soil mixture by means of an aspirating hopper dredger comprising a suction mouth with a wall defining a chamber with an opening for the connection of an aspirating tube. The suction mouth comprises a fin shaped as a rotating protective visor to which a scraper blade disposed outside the chamber is attached. Within the suction nozzle there is at least one nozzle for directing at least one water jet on the material located next to a second portion of the scraper blade inside the chamber, the direction of the jet flow being substantially parallel to the direction of aspiration. In this way the scraped earth is shredded by water jets and sucked into the suction mouth.

A dredger with suction hoppers It consists of a structure connected to a suction tube, the which is open on the lower side and that crawls on the ground during dredging.

The dredging head itself consists of two parts: a cap that is connected directly to the tube suction of the boat, and a protective visor that is connected by hinge to the lid by means of a horizontal axis. On the visor  protective there are a series of teeth 4 applied on one arm in order of breaking the ground Said arm is known as toothed arm.

On the lower side of the lid, at the height of the connection with the protective visor, a series of wear heel parts. These pieces form the plate of heel. In these wear heel parts there is a number of nozzles

During dredging, the head moves over the ground. In this way, the head rests on the ground by means of of the heel plate. Since the protective visor can move regardless of the lid, the latter rests with the wall lateral and / or posterior on the ground. Depending on the hardness of the floor, these walls will more or less penetrate the floor. Through the aspirating action of the dredge pump at the end of the tube of aspiration, finally a depression will form in the head of dredging which, among others depends on the degree of closure of said head, chief, engine head. With this, along with the outside water, which should be inevitably supplied, a quantity of sand will be sucked. From in this way, the sand is dredged by the erosive action of the Water.

Sand production is now increased thanks to two additional elements:

to)

Teeth: due to teeth existing in the protective visor, we proceed to peel a layer of the ground when the head passes. In this way, the broken earth It can then be aspirated.

b)

Jets: in the wear parts of heel are one or more nozzles. Through them, Currently, water is pumped at a pressure of approximately 10 Pub. This allows extra sand to be aspirated, since:

Sand to dredge consists of stacked grains. These are squeezed over each other by their own weight. Bliss pressure is transferred between the grains by support points mutual, finding the points of contact between the grains.

It is this pressure that guarantees that the grains remain in some way at rest: the grains are tight in a certain state of equilibrium

If you want to vacuum this sand, you have to disturb that balance. This can be achieved using the jets: feeding water under pressure, pressure can be eliminated mutual among the grains. This eliminates the force that maintains the grains on each other, causing the grains to start moving. These grains try to reach another state of equilibrium, and this is What is called fluidization of sand. Now so you just have to vacuum this sand, which can be achieved by the depression formed in the dredging head.

In general it can be said that the jets serve to release the sand, and that the suction force of the pump of Dredging is used to transport loose sand.

Trailed hoppers that are already known corresponds to the aforementioned.

The object of the invention is to design a head of dredged that, thanks to a number of modifications and improvements, shows an increase in performance, between others thanks to an increase in the concentration of sand in the mixture pumped, for which there are preferably means to adjust Water space regardless of cutting thickness.

In order to allow this, a head of dredging according to claim 1, in which, behind the teeth mentioned above, always with reference to the sense of dredging head movement, there is at least a second series of blasting tubes.

As mentioned above, the sand to dredging consists of stacked grains that are squeezed over each other By its own weight. The passage of the first series of nozzle tubes causes the grains to a first depth to be released between them and fluidizes the soil to the first depth. He step of the teeth disturbs the ground to the first depth, causing it to be aspirated. In addition, the passage of the teeth breaks the sand, that is to say, causes the grains to be released between them to a second increased depth, creating cavities and causing a depression in the ground to this second depth. Providing the second series of nozzle tubes, the cavities that are created between the grains of sand are immediately filled with water and depression is minimized, which can ensure that grains to the second depth, remain separated between them and aspire with the flow of aspiration.

It should be mentioned that from the patent JP60055133 is known a device for digging trenches, which employs a plurality of water jet nozzles mounted on a plurality of plow blades. The JP60055133 patent plow It is used to make a ditch underwater to house cables, pipes, and the like, and therefore simply pushes the material from the ground under water to the sides, that is outside the leaves.  JP60055133 does not refer to a dredging head for dredge that, on the contrary, aims to collect and aspirate the soil material under water through a tube of aspiration. JP60055133 only indicates that the performance of excavation can be improved by using jets of water, however, does not indicate that the use of a plurality of jets water really improves the suction performance of the material ground.

Always according to the invention, the before cited second series of blasting tubes is subdivided preferably in blasting tubes directed to the interior of the protective visor, more particularly on said teeth, and in blasting tubes that are directed vertically or substantially downward.

Other details and advantages of the invention will be given manifested in the following description of a dredge head according to the invention. This description is provided. by way of example only and does not limit the invention. The reference numbers are those that appear in the figures attached.

Figure 1 is a schematic side view of the dredging head according to the invention;

Figure 2 is a representation in perspective, on a larger scale, of the dredging head according to the invention;

Figure 3 schematically illustrates the working depth of a dredge head of known type; Y

Figure 4 illustrates, in the same way, the possible Working depth of the dredging head according to the invention.

The dredging head for a dredger with hoppers towed aspirant, according to the invention, is moved on the ground in the direction of arrow P represented in figure 1. The dredging head according to the invention is in the end of a suction tube 1 that is equipped with a visor protective 2 consisting of side walls 3, a wall 3 'back, a top plate 4 with an arc-shaped section 5, that once the protective visor 2 is rotated around its axis 6 remains in intimate contact with the closure strip 7 that belongs to the fixed parts that are mounted on the suction tube. During dredging, in fact a depression is maintained within the protective visor, and currently constitutes a clear object of invention increase the sand fraction of dredged sludge. TO through the heel plates 8 pass a number of tubes of blasting 9, which inject water at high pressure. Until the presently heel plate 8 is used with the blasting tubes 9 applied on the front. During the dredging the dredging head on the ground, the jets injected first they will release the sand, which will then be immediately aspirate. At the same time, teeth 10, which are behind of the blasting tubes 9, they will break the sand. (In this text, the terms "in front of" and "behind" should be understood with with respect to the direction of movement of the dredging head). These teeth are also found in existing dredging heads until now.

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Behind said teeth 10, at the height of the water valve 11 that closes the protective visor on the rear side, there is now a second series of blasting tubes. These blasting tubes are subdivided into a first series of blasting tubes 12 that are directed towards the teeth 10, and a second series of blasting tubes 12 'that are directed vertically or substantially vertically downwards. The jets injected through the blasting tubes 12 are directed towards the inside of the protective visor. The blasting tubes 12 'are intended to give better fluidity to the floor, that is, reach deeper into the wall

 \ hbox {later 3 '.} 

The presence of blasting tubes 12 and 12 ' It has the following advantages:

to)

The sand released by teeth 10 and blasting tubes 9 which it had not yet been aspirated again becomes fluidized and so can aspire better.

b)

The multi-stage fracture by means of blasting tubes 9 by one side, and the blasting tubes 12 and 12 'on the other hand, increases the depth that agitates and sucks the sand. This can be clearly discovered by comparing the depth of work according to figure 3 and working depth according with figure 4.

C)

A performance increase through the water space. While before, only a mixture of sand and water passed through the water space by erosion, now the concentration of the mixture increases by erosion and by the presence of fluidized sand as consequence of the action of the blasting tubes located immediately in front of the water space.

The advantages explained here are the answer immediate change of the blasting tubes 12, 12 ' immediately behind the teeth 10.

The different blasting tubes 12, 12 'are link immediately with a water valve 11 that can move,  and this according to a translation that occurs in a plane that runs parallel to the rear wall 3 'of the protective visor. This Water valve 11 is designed in the form of a water chamber 13. In case of hydraulic work, this is carried out from the dredged hopper dredger hopper bridge. The assembly of the water valve that can be adjusted in the direction of height, further increases the efficiency of the new dredging head, since the water space can be optimally adjusted in function of soil conditions and totally independent of soil penetration through the visor protective

The effectiveness of dredge hopper suction towed is further increased by applying at the bottom of the side walls 3 of the protective visor, one or more series of several blade-shaped side wear slats 14. These wear strips are thin enough to penetrate inside the sand in order to achieve the desired closure, so that the sand / water ratio of the aspirated mixture is still optimized plus.

In order to prevent the water supplied from being fed along the relatively unproductive sides of the protective visor, the dredging head must be well Closed in these places. The side walls of the visor protective should penetrate well into the ground.

Through the presence of wear strips thin-walled 14, the protective visor is perfectly closed laterally, so that the necessary transport water is completely sucked in the back through the space of water and agitated soil. This new configuration forms a Second important features of the invention.

It should be seen as another improvement of dredge head the presence on the back side of the head dredging the hinged legs 15 with respect to the visor protective, the useful surface of which, i.e. the base 15 ', is large enough to ensure a fixed support in the ground. Regulating the depth of the legs 15, which are mutually connected to a plate 17 (figure 2), the penetration of the protective visor and therefore of the teeth in soil. This allows the thickness of the teeth to be adjusted, and this regardless of the water space. In a possible way of embodiment, the legs 15, with their widened bases 15 'are swivel mounted around a hinge point 18. The rotation it is carried out by means of the action of the hydraulic cylinder 16, with the hinge point 18 with respect to legs 15 and hinge point 19 with respect to the protective visor. The protective visor itself it is raised and lowered by the action of the hydraulic cylinder 20. The cylinder 20 is rigidly fixed with respect to the tube of suction 1 and is connected, by way of hinge at 21, to the parts fixed that correspond to the structure of the protective visor, to end of raising and lowering the back 3 'thereof.

In figure 2 one of the hydraulic cylinders 22, which controls the water valve 11.

Increasing the working pressure of the jets of water from 10 to 20 bar, a penetration can be provided remarkably best of such water jets. This constitutes a characteristic of the invention

By combining the different improvements to a dredge head of known type, as it has been explained above, a surprising increase in performance of the new dredging head.

Claims (8)

1. A dredging head for a towed hopper dredger, consisting essentially of a structure connected to a suction tube, with a protective visor (2) that rotates around a horizontal axis (6), in which there are applied a series of teeth (10) to break the sand that are arranged along a line that extends perpendicularly with respect to the direction of movement of the dredging head, and a first series of blasting tubes (9) to inject water at high pressure, which are arranged along a line parallel to the line and in front of or behind said teeth, characterized in that at least a second series of blasting tubes (12, 12 ') exists behind the line of said teeth teeth, aiming at the blasting tubes (12, 12 ') of each second series to fluidize, in operation, the soil to be aspirated. A dredging head according to claim 1, characterized in that said second series of blasting tubes has a water valve (11) in the form of a water chamber (13) that can be moved hydraulically in a plane that extends tangentially or substantially tangentially to the rear wall (3 ') of the protective visor. 3. A dredging head according to claim 1 or claim 2, characterized in that the second series of blasting tubes (12) is subdivided into blasting tubes (12) directed inside the protective visor and blasting tubes ( 12 ') directed vertically or substantially vertically downwards. 4. A dredging head according to claim 3, characterized in that the blasting tubes (12) directed towards the inside of the protective visor are directed on the teeth (10). A dredging head according to any one of claims 1 to 4, characterized in that in the protective visor (2), together with the aforementioned suction tube (1), there are adjustable legs (15) whose useful surface (15 ') is large enough to provide support on the ground, so that the protective visor, at the bottom of the side walls 3' is equipped with blade-shaped wear slats (14) that are thin enough to penetrate into the floor and guarantee the desired lateral closure. A dredging head according to any one of claims 1 to 5, characterized in that the second series of blasting tubes (12, 12 ') is mounted at the height of the rear wall (3') of the protective visor. A dredging head according to any one of claims 1 to 6, characterized in that the second series of blasting tubes (12, 12 ') is mounted immediately behind the teeth (10). A method for dredging with an aspirating hopper dredger equipped with a dredging head according to any one of claims 1 to 7, characterized in that the pressure in the jet tubes is increased to
20 bar