Dredging equipment and method for dredging or mining with such equipment

Abstract

 Dredging equipment (1) which comprises a vessel (2), a pumping line and one or more suspension-wire systems (39, 54) on the vessel (2) which are linked to the pumping line (8) wherein the pumping line (8) is an articulated pumping line with two or more pumping line sections, which can be folded into a reduced status in which at least some of the pumping line sections (28, 32,33) are brought parallel and near to one another over a substantial part of their length, which can be unfolded into an extended status and be brought in the submerged position for use of the pumping means (7).

Description

[0001] The present invention relates to dredging equipment.

[0002] In particular the invention relates to dredging equipment of a type which comprises at least:

• a vessel;
• pumping means ; and,
• one or more suspension-wire systems on the vessel each with hoisting means for winding and unwinding one or more wires which are linked to the pumping means.

[0003] More specifically, the invention relates to such dredging equipment wherein the pumping means comprise at least:

• a pumping line, which consists of a suction tube, a submergible pump and a discharge tube;
• an inlet of the submergible pump which is connected to a first extremity of the suction tube and an outlet of the submergible pump which is connected to a first extremity of the discharge tube;
• a second extremity of the suction tube being a free end forming a suction tube inlet for sucking a mixture of water and loosened seabed material;
• a trunnion slide connection of the pumping line with the vessel at the second extremity of the discharge tube, which is such that the pumping line can be moved between an onboard position for storing the pumping line on board of the vessel and a submerged position outboard the vessel and beneath the water level for use of the pumping line.

[0004] Furthermore, the vessel for the dredging equipment can be of a type wherein the dredged material is loaded in its own hopper, but also barges for discharging the dredged material can be used.

[0005] Such type of dredging equipment is already known according to the state of the art.

[0006] Nevertheless, it is according to the invention possible to improve substantially this type of dredging equipment.

[0007] Indeed, until approximately 1975, the maximum dredging-depth achievable by hydraulic dredgers was about 60 m to 70 m below water-level.

[0008] The sizes and the hydraulic capacities of hydraulic dredgers prevented from working at greater depths.

[0009] Mankind is however searching for marine resources for both commercial minerals and building materials at ever greater water depths.

[0010] This search is triggered by the growing upland scarcity in sand, mine-materials, etc...

[0011] In more recent years dredging equipment was developed and the maximum achievable dredging depth increased gradually.

[0012] Nevertheless, this new dredging equipment generally requires a complete new design of the vessel and its composing dredging elements and as a consequence very high investment costs are involved.

[0013] Furthermore, the search for appropriate and improved dredging equipment - capable of working in high seas, achieving large productivities and providing reliability in supply - continues and the present invention is related hereto.

[0014] It is therefore an objective of this invention to provide an improvement to one or more of the above-mentioned parameters of the existing dredging equipment, as well as to provide solutions to possibly not-mentioned problems.

[0015] In particular, it is also an intention of the present invention to provide improved dredging equipment, additional technology being incorporated in a dredger of a known type without having to modify the essence of the known dredger's structure.

[0016] Hereby the aim is to keep the existing ship's infrastructure, like heave-compensators, gantries, winches, upper sections of the suction-tube and pump-installations.

[0017] Furthermore it is at the same time an intention of the invention to keep the existing dredging-process substantially unchanged, while allowing to achieve dredging at great water depths (beyond 165 m) with large productivities (beyond 20.000 m3/hour).

[0018] To this end, the present invention relates to dredging equipment of a type in accordance with the preambule of claim 1, wherein additionally, according to the invention, the pumping line is an articulated pumping line comprising two or more pumping line sections, adjacent pumping line sections being connected to one another in a rotatable manner by means of an articulation, different parts of the pumping means being linked to a wire or to wires of an above-mentioned suspension-wire system in such a way that, on the one hand, by winding the concerned wires the articulated pumping line can be folded into a reduced status with reduced dimensions and be brought in the onboard position, in which reduced status at least some of the pumping line sections are brought parallel and near to one another over a substantial part of their length, and, on the other hand, by unwinding the concerned wires the articulated pumping line can be unfolded into an extended status with extended dimensions and be brought in the submerged position for use of the pumping means, in which extended status the pumping line sections are distant from one another except at their interconnection by means of the concerned articulation.

[0019] A big advantage of dredging equipment in accordance with the present invention is that seabed material can be dredged at much greater depths by a rather small modification of existing dredger equipment, without having to completely modify the existing dredger equipment.

[0020] Indeed, the modification mainly consists in adding a pumping line extension part for forming an articulated pumping line in the described manner which can be folded and unfolded between a reduced and extended status, and providing one or more additional suspension-wire systems on an existing dredger of the concerned type.

[0021] Of course such a solution is very advantageous from an economical point of view.

[0022] What's more, as will be demonstrated further, the articulated pumping line can be easily stored on the vessel and deployed for being used below the water-level, resulting in a highly efficient dredging method.

[0023] Furthermore, the characteristic that the articulated pumping line can be unfolded into an extended status for dredging or mining at a great depth and can be folded back into a reduced status for storing on the vessel is very interesting to save a lot of space.

[0024] Another advantage of the articulated type of pumping line is that its dynamic behavior is still quite rigid and therefore still easy to control, as contrary to the dynamic behavior of pumping lines of the flexible type.

[0025] According to a preferred embodiment of dredging equipment in line with the present invention the afore-mentioned articulated pumping line comprises a pumping line vessel-side part and a pumping line extension part connected to one another in a rotatable manner at a first of their extremities by means of a first articulation, the pumping line vessel-side part being provided at its second extremity with said trunnion slide connection of the pumping means with the vessel and being suspended with respect to the vessel at least partly by means of the wire or wires of a pumping line vessel-side part suspension-wire system, and the pumping line extension part having at its second extremity a free end forming the suction tube inlet and being suspended at least partly to the vessel by means of the wire or wires of a pumping line extension part suspension-wire system.

[0026] The pumping line vessel-side part suspension-wire system could be a suspension wire system of an existing dredger, whereas only a pumping line extension part suspension-wire system for controlling the movement of an added pumping line extension part has to be added for substantially augmenting the dredging depth.

[0027] According to the invention the pumping line vessel-side part has preferably a length which approximately corresponds to the length between the position of the trunnion slide connection of the pumping means with the vessel and the stern of the vessel.

[0028] With such an embodiment of dredging equipment in accordance with the present invention the available space on the vessel is very efficiently used.

[0029] Indeed, in the reduced status of the pumping line one or more sections of the pumping line extension part are positioned parallel and near to one or more sections of the pumping line vessel-side part, so that the length of the total length of the pumping line stored on the vessel is much bigger than with pumping lines which cannot be folded into a reduced status.

[0030] According to another aspect of the present invention all the articulations provided between pumping line vessel-side part sections are cardan couplings, allowing a limited rotation of the different pumping line vessel-side part sections with respect to one another.

[0031] An advantage of such an embodiment of dredging equipment in accordance with the invention is that the different sections of the pumping line vessel-side part can be kept rather easily in line, for forming a straight pumping line part, while still allowing some misalignments by means of cardan couplings, so that no extreme bending forces on the pumping line vessel-side part are introduced.

[0032] Similarly, it is preferred according to the present invention that the first articulation between the pumping line vessel-side part and the pumping line extension part is a swivel coupling, allowing a rotation over 360° of the concerned parts with respect to one another.

[0033] An advantage of this embodiments of dredging equipment according to the invention is of course that the articulated pumping line can be easily brought into a reduced status for storing the dredging equipment on the vessel by rotating the pumping line extension part against the pumping line vessel-side part over the swivel.

[0034] On the other hand, such dredging equipment can also be easily deployed by rotating the pumping line extension part in the opposite sense into a distant position with respect to the pumping line vessel-side part.

[0035] The combination of the different types of coupling between sections of the pumping line as proposed above provides in a good dynamic behavior of the complete pumping line, having, on the one hand, a rather rigid structure, but being somewhat flexible on the other hand due to the presence of the couplings forming the articulations of the pumping line.

[0036] Another preferred characteristic of dredging equipment in accordance with the invention is that the wire or wires of the pumping line extension part suspension-wire system is or are preferably linked with one end to the suction tube inlet and is or are preferably partly wound at a second end on a winch on the deck of the vessel, while the concerned wire or wires passes or pass from the winch over a gantry on the deck and further over a roller cage which is fixed to the pumping line vessel-side part.

[0037] An advantage of this embodiment of dredging equipment in accordance with the invention is that by winding the wire or wires of the pumping line extension part suspension-wire system a pulling force can be created between the suction tube inlet on the pumping line extension part and the roller cage on the pumping line vessel-side part, so that both concerned pumping line parts are pulled towards one another and are rotated towards one another so that the pumping line is easily brought into the reduced status.

[0038] Of course, by unwinding the concerned wires the opposite movement is obtained for unfolding the articulated pumping line.

[0039] The present invention also relates to a method for dredging or mining with dredging equipment in accordance to the invention as described above, the method comprising at least the following steps:

• sailing the vessel towards an area to be dredged or mined, the pumping line being in a reduced status;
• unwinding wires of the suspension-wire systems for bringing the pumping means into a submerged position and unfolding the articulated pumping line into an extended status until the suction tube inlet reaches the seabed;
• dredging or mining the concerned area by pumping a mixture of seabed material and water into the vessel or into a barge; and,
• winding wires of the suspension-wire systems for folding the articulated pumping line into a reduced status and bringing the pumping means in the onboard position for storing it on board of the vessel after dredging or when the load capacity of the vessel is reached.

[0040] Such a method for dredging or mining according to the invention is very advantageous, since a good balance is obtained between the storage space needed on the vessel for storing the pumping means and a structure of the pumping line which is rather rigid but having an easily controllable dynamic behavior when in use, certainly when compared to dredging equipment having a pumping line which consists of a flexible tube.

[0041] With the intention of better showing the characteristics of the invention, hereafter, as examples without any limitative character, a preferred form of embodiment is described of dredging equipment in accordance with the invention, as well as a dredging method in accordance with the invention wherein the dredging equipment is used, with reference to the accompanying drawings, wherein:

figure 1 represents a side view on dredging equipment according to the invention the pumping line being stored on board in the reduced status;

figures 2 to 5 represent side views similar to the side view of figure 1, respectively at subsequent steps during unfolding of the pumping line of the dredging equipment into an extended status fur use;

figure 6 represents on a larger scale the part of figure 3 indicated with F6; and,

figures 7 to 10 are also on a larger scale perspective views of parts of the pumping line, indicated in figure 4 respectively by arrows F7 to F10.

[0042] The embodiment of dredging equipment 1 according to the present invention represented in figures 1 to 5 comprises first of all a vessel 2 with a hull 3, having a bow or foremost part 4 and a stern or aft-most part 5, as well as a deck 6.

[0043] The dredging equipment 1 also comprises pumping means 7 which comprises a pumping line 8.

[0044] This pumping line 8 is composed of a suction tube 9, a submergible pump 10 and a discharge tube 11.

[0045] The inlet 12 of the submergible pump 10 is connected to a first extremity 13 of the suction tube 9 and the outlet 14 of the submergible pump 10 which is connected to a first extremity 15 of the discharge tube 11.

[0046] The second extremity 16 of the suction tube 9 is a free end which forms a suction tube inlet 17 for sucking a mixture of water and loosened seabed material 18.

[0047] At the second extremity 19 of the discharge tube 11 the pumping line 8 is connected to the vessel 2 by means of a a trunnion slide connection 20.

[0048] This trunnion slide connection 20 is such that the pumping line 8 can be moved between an onboard position, as is represented in figure 1, for storing the pumping line 8 on board of the vessel 2, and a submerged position outboard the vessel 2 and beneath the water level 21 for use of the pumping line 8, as is represented in the subsequent figures 2 to 5.

[0049] The trunnion slide connection 20 is represented in more detail in figure 6.

[0050] Hereby, an elongated trunnion slide guide 22 is provided along a sidewall 23 of the hull 3 of the vessel 2 which extends in a vertical direction AA' from the bottom 24 of the hull 3 to a position above the deck 6 of the vessel 2.

[0051] Furthermore, the trunnion slide connection 20 is such that, on the one hand, the second extremity 19 of the discharge tube 11 can rotate in the slide guide 23 around an axis which is perpendicular to the concerned sidewall 23.

[0052] On the other hand, the second extremity 19 of the discharge tube 11 can move upwards and downwards in the slide guide 22 along the concerned sidewall 23 of the hull 3 in the vertical direction AA' between a downward position, represented in figure 2, for connection to a discharge pipe mounted inside the hull 3, which discharge pipe is not visible in the figures, and an upward position in the vicinity of the deck level 6 of the vessel 2, represented in figure 1.

[0053] The pumping means 7 further comprise a water-jet pipe 25 mounted along the pumping line 8, as is more visibly represented in the enlarged views of figures 7 to 10.

[0054] This water-jet pipe 25 provides water to nozzles 26 arranged around the suction tube inlet 17 for loosening the seabed material 18, as can be seen in figure 10.

[0055] Therefore, the nozzles 26 are orientated such that water provided by the water-jet pipe 25 is projected in a sense away from the suction tube inlet 17, in a direction which is somewhat diverging from the axial direction BB' of the suction tube 9 at the suction tube inlet 17 extremity.

[0056] Nevertheless, it is not excluded according to the invention to use other tools for loosening the seabed material, or to omit such tools in the case the soil is consisting of very loose material.

[0057] Furthermore, the dredging equipment 1 is also provided with several suspension-wire systems on the vessel 2 each with hoisting means for winding and unwinding one or more wires which are linked to the pumping means, the particular details of which in the represented case will be given somewhat further.

[0058] In the most general terms, an important characteristic of dredging equipment according to the invention is that the pumping line 8 is an articulated pumping line 8 comprising two or more pumping line sections, adjacent pumping line sections being connected to one another in a rotatable manner by means of an articulation.

[0059] In the embodiment under discussion, the articulated pumping line 8 comprises a pumping line vessel-side part 27 and a pumping line extension part 28 connected to one another in a rotatable manner at a first of their extremities, respectively first extremity 29 and first extremity 30, by means of a first articulation 31.

[0060] The pumping line vessel-side part 27 is provided at its second extremity, which is also the second extremity 19 of the discharge tube 11, with the trunnion slide connection 20 by which the pumping line 8 is connected to the vessel 2.

[0061] The pumping line extension part 28 has at its second extremity, which is also the second extremity 16 of the suction tube 9, a free end forming the suction tube inlet 17.

[0062] Typically, according to the invention the pumping line vessel-side part 27 will have a length L which corresponds approximately to the length M between the position of the trunnion slide connection 20 of the pumping means 7 with the vessel 2 and the stern 5 of the vessel 2.

[0063] This length M is more or less the length on board of the vessel 2 which is available for storing parts of the pumping line 8.

[0064] Therefore, the pumping line vessel-side part 27 also corresponds to that part of the pumping line 8 which is forming a pumping line in the known types of dredging equipment.

[0065] The pumping line extension part 28 on the other hand has a length N and corresponds to a part of the pumping line which would be typically not be available in a known dredger.

[0066] It is therefore the part of the pumping line 8 by which the maximum dredging depth D is extended in dredging equipment 1 according to the invention compared to the maximum dredging depth E realizable with existing dredger equipment of the same type.

[0067] Supposed that this pumping line extension part 28 could be positioned exactly vertical when the pumping line 8 is in use, which is only approximately true as is represented in figure 5, the depth F by which the maximum dredging depth E obtainable with the known types of dredging equipment of a similar type is increased corresponds to the length N of the pumping line extension part 28.

[0068] The pumping line extension part 28 consists in the embodiment represented in the figures of a single rigid suction tube section 28 without any further articulation, apart from the first articulation 31.

[0069] Nevertheless, according to the invention the pumping line extension part 28 can be composed of more than one pumping line extension part section as well, adjacent pumping line extension part sections being connected to one another in a rotatable manner by means of an articulation.

[0070] Furthermore, in the embodiment of dredging equipment 1 according to the invention represented in the figures, the pumping line vessel-side part 27 is on the contrary composed of multiple pumping line vessel-side part sections, adjacent pumping line vessel-side part sections being connected to one another in a rotatable manner by an articulation.

[0071] In particular the pumping line vessel-side part 27 consists of three pumping line vessel-side part sections 32 to 34.

[0072] A first pumping line vessel-side part section 32 will be indicated hereafter as the top pumping line vessel-side part section 32 and is connected in a rotatable and movable manner with an extremity, which is also the second extremity 19 of the discharge tube 11 or the pumping line vessel-side part 27, to the vessel 2 by means of the trunnion slide connection 20.

[0073] The submergible pump 10 as well as the complete discharge tube 11 are in this case included in this top pumping line vessel-side part section 32.

[0074] A second pumping line vessel-side part section 33 will be indicated hereafter as the bottom pumping line vessel-side part section 33 and is connected in a rotatable manner at an extremity, which is also the first extremity 29 of the pumping line vessel-side part 27, by means of the first articulation 31 to the pumping line extension part 28.

[0075] The third line vessel-side part section 34 will be indicated hereafter as the intermediate pumping line vessel-side part section 34 mounted in a rotatable manner, on the one hand, at its first extremity 35 to the bottom pumping line vessel-side part section 33 by means of a second articulation 36, and on the other hand, at its second extremity 37 to the top pumping line vessel-side part section 32 by means of a third articulation 38.

[0076] Nevertheless, according to the invention it is not excluded to provide a pumping line vessel-side part 27 which consist of only one single rigid pumping line vessel-side part section having no further articulations or which is composed of another number of pumping line vessel-side part sections 27.

[0077] The articulations of the pumping line 8 can be of any type.

[0078] For example, such an articulation can be formed by a cardan coupling, allowing a limited rotation of the adjacent pumping line sections.

[0079] In the embodiment represented in the figures all the articulations 36 and 38 provided between the pumping line vessel-side part sections 32 to 34, i.e. the second articulation 36 and the third articulation 38, are such cardan couplings, represented in more detail in figures 7 and 8 respectively.

[0080] This is however not required according to the invention although preferred.

[0081] As an alternative, an articulation of the pumping line can also be formed by a swivel coupling for example, allowing a rotation over 360° of the adjacent pumping line sections.

[0082] In the embodiment represented in the figures the articulation 31 between the pumping line vessel-side part 27 and the pumping line extension part 28, i.e. the first articulation 31, is such a swivel coupling, represented in more detail in figure 9.

[0083] Nevertheless, according to the invention this articulation 31 could be of another type as well.

[0084] On the other hand, the characteristic that the pumping line extension part 28 and the pumping line vessel-side part 27 can rotate over a full circle, whereas adjacent pumping line vessel-side part sections 32 to 43 can only rotate over a limited angle with respect to one another is interesting in that the pumping line vessel-side part 27 can be easily kept more or less in a straight line while the pumping line extension part 28 and the pumping line vessel-side part 27 can be easily folded in a reduced status, as represented in figures 1 and 2, or on the contrary, be unfolded into an extended status, as is for example the case in figure 5.

[0085] Actually, this is another important aspect of dredging equipment 1 in accordance to the present invention and can also be considered as a kind of definition of what is meant by the pumping line vessel-side part 27, i.e. the part that is directly connected to the vessel 2 and is stored as a straight part of the pumping line 8 on the vessel 2 regardless of the fact whether it consists of multiple pumping line vessel-side part sections 32 to 34 or not.

[0086] Similarly, the pumping line extension part 28 can be defined as an additional part of the pumping line 8 which is stored on board of the vessel 2 in parallel and near to the pumping line vessel-side part 27, regardless of the fact whether or not it consists of multiple pumping line extension part sections, or whether or not such multiple pumping line extension part sections would be stored as a straight pumping line part or as multiple straight pumping line parts stored in parallel and near to one another.

[0087] The water jet pipe 25 is of course at each articulation 31, 36 and 38, provided with similar means for allowing a rotation between different sections of the water-jet pipe 25.

[0088] In order to be able to fold and unfold the articulated pumping line 8, different parts of the pumping means 7 are linked to a wire or to wires of a suspension-wire system or multiple suspension-wire systems.

[0089] In the case represented in the figures the pumping line vessel-side part 27 is at least partly suspended with respect to the vessel 2 by means of the wire or wires of a pumping line vessel-side part suspension-wire system 39.

[0090] In particular, a part of the pumping line vessel-side part suspension-wire system 39 is formed by a first hoisting means 40 having a set of wires 41 which are linked to the pumping line vessel-side part 27 in the vicinity of or on the first articulation 31.

[0091] This first hoisting means 40 are in this case provided in the vicinity of the stern 5 of the vessel 2, forming an aft ship pumping line suspension-wire system 40.

[0092] The set of wires 41 comprises in this case a double reeved wire 42, having a length of at least 310 m, and which is directly linked to the first articulation 31, i.e. swivel coupling 31, whereby the double reeved wire 42 is passed over a sheave 43 which is mounted on the swivel 13 and the double reeved wire 42 can be wound and unwound by means of a winch on board of the vessel 2.

[0093] Additionally, the set of wires 41 comprises a single wire 44, which is connected to the bottom pumping line vessel-side part section 33 in the vicinity of the swivel coupling 31 and which can be wound and unwound by means of a separate winch of the first hoisting means 40 on the vessel 2.

[0094] Furthermore, the pumping line vessel-side part suspension-wire system 39 comprises a second hoisting means 45 having a set of wires 46 which are linked to the intermediate pumping line vessel-side part section 33 in the vicinity of or on the second articulation 36, i.e. the cardan coupling 36.

[0095] In the embodiment represented in the figures the set of wires 46 consists of a double reeved wire 46, having a length of at least 186 m, which is passed over a sheave 47 mounted on the intermediate pumping line vessel-side part section 33 in the vicinity of the cardan coupling 36 and which can be wound and unwound by means of a winch on board of the vessel 2.

[0096] Similarly, the pumping line vessel-side part suspension-wire system 39 also comprises a third hoisting means 48 having a double reeved wire 49 which is passed over a sheave 50 which is mounted on the top pumping line vessel-side part section 34 in the vicinity of the third articulation 38, i.e. cardan coupling 38.

[0097] Still another part of the pumping line vessel-side part suspension-wire system 39 consists of a fourth hoisting means 51 having a single wire 52 which is hooked to the second extremity 19 of the pumping line vessel-side part 27 at the trunnion slide connection 20, as can be seen more clearly in figure 6.

[0098] This fourth hoisting means 51 are provided on the vessel 2 in vertical alignment with the trunnion slide guide 22.

[0099] Summarized it can be said that the pumping line vessel-side part 27 is at least partly suspended to the vessel 2 by means of the combination of the four hoisting means 40, 45, 48 and 51.

[0100] An interesting aspect of the configuration used in the embodiment of the figures is that each pumping line vessel-side part section 32 to 34 is at least suspended by a separate wire or a separate set of wires 42,44,46 and 49 of the pumping line vessel-side part suspension-wire system 39, the separate wire or separate set of wires 42,44,46 and 49 being linked to the concerned pumping line vessel-side part section 32 to 34 in the vicinity of an articulation at the side of the concerned pumping line vessel-side part section 32 to 34 which is the most distant from the vessel 2.

[0101] Hereby, an extremity of each said separate wire or set of separate wires 42,44,46 and 49 of each pumping line vessel-side part section 32 to 34 is or are wound on a corresponding separate winch and passed over a corresponding gantry of the pumping line vessel-side part suspension-wire system 39 provided on the vessel 2 at a distance from the fourth hoisting means 51 corresponding to the distance between the second extremity 19 of pumping line vessel-side part 27 and the connection of the concerned wire or wires 42,44,46 and 49 with the pumping line vessel-side part 27.

[0102] With such a configuration the moment arms for moving the different pumping line vessel-side part sections 32 to 34 are optimized and the position of the different pumping line vessel-side part sections 32 to 34 can be accurately set.

[0103] Also the pumping line extension part 28 is at least partly suspended to the vessel 2 by means of the wire or wires of a pumping line extension part suspension-wire system 54, which is in the embodiment of the figures simply formed by fifth hoisting means.

[0104] In particular this fifth hoisting means 55 is provided with a wire 56, with a length of at least 250 m, which is linked with one end to the suction tube inlet 17 and which is partly wound at a second end on a winch on the deck 6 of the vessel 2.

[0105] Furthermore, the concerned wire 56 passes from the winch over a gantry on the deck 2 and further over a roller cage 57 which is fixed to the pumping line vessel-side part 27, in this case on the intermediate pumping line vessel-side part section 34 in the vicinity of the second articulation 36.

[0106] In that way an interaction is obtained between the pumping line extension part 28 and the pumping line vessel-side part 27 when the wire 56 is pulled or released at another speed than the wires of the pumping line vessel-side part suspension-wire system 39, so that the pumping line extension part 28 and the pumping line vessel-side part 27 can be rotated with respect to one another by means of the first articulation 31.

[0107] The second hoisting means 45 and the pumping line extension part suspension-wire system 55 formed by the fifth hoisting means 56 are provided approximately at half of the length of the vessel 2, and can be considered as forming together a mid-ship pumping line suspension-wire system 58.

[0108] According to the invention it is preferred to provide the different suspension-wire systems 39 and 45 with heave compensators in order to control the tension by avoiding that wires become temporarily loose and on wires so that the pumping line 8 is kept stable.

[0109] Furthermore, it is preferred according to the invention to provide the suction tube inlet 17 with a shock absorber 59, an example of which is represented in figure 10.

[0110] The shock absorber 59 comprises two concentric telescopic pipes, i.e. an inner pipe and an outer pipe, not visible in figure 10, and a spring 60 mounted between or over the telescopic pipes which spring 60 is compressed when the inner pipe is pushed into the outer pipe.

[0111] In this manner, shocks between the suction tube inlet 17 and the seabed 18 induced by movements of the vessel 2 can be absorbed, so that no other parts of the pumping line 8 are subjected to such kind of shocks or at least on a very reduced level.

[0112] At great water-depths, the vacuum in the suction tube 9 created by the pumping of the submergible pump 10 may induce implosions or water-hammering.

[0113] Therefore, another aspect according to the invention is that the pumping line 8 is preferably provided with vacuum relief valves 61 in order to prevent such phenomenon from occurring or causing damage.

[0114] These vacuum relief valves 61 may be of an active or passive type and compensate for the concerned pressure differences and will allow regular flow through the pumping line 8.

[0115] In the embodiment of dredging equipment 1 represented in the figures the top pumping line vessel-side part section 32 and the intermediate pumping line vessel-side part section 34 are metal tube sections, whereas the bottom pumping line vessel-side part section 33 and the pumping line extension part 28 comprise one or more plastic pipes which are provided in a metal lattice girder 62.

[0116] These lattice girders 62 also increase the resistance of the pumping line 8 against shocks in the pumping line 8.

[0117] The bottom pumping line vessel-side part section 33 and the pumping line extension part 28 may be constructed from a light weight glass-reinforced epoxy (GRE) pipe or any other plastic material.

[0118] According to a preferred embodiment of dredging equipment 1 in line with the invention the suction tube inlet 17 is provided with sensors for measuring the position of the suction tube inlet 17 with respect to the vessel 2 and which provide an input for a controller which controls the position of the suction tube inlet 17 by means of the suspension-wire systems 39 and 54.

[0119] The wire or wires of the suspension-wire systems 39 or 54 are hereby preferably provided with an interactive wire-tensioning control system by which the tension in the corresponding wires is kept within certain limits.

[0120] For using the dredging equipment 1 in accordance with the invention a method for dredging or mining according to the invention is proposed as follows.

[0121] First, the vessel 2 is sailed towards an area to be dredged or mined the pumping line 8 being in a reduced status, as represented in figure 1 stored on board of the vessel.

[0122] Upon positioning of the vessel 2, ready for operations, the pumping line 8 is lifted from its cradles on deck 6 and swung overboard.

[0123] Then the pumping means 7 are brought into a submerged position and the articulated pumping line 8 is unfolded into an extended status by unwinding the wires 42, 44, 46, 48, 52 and 56 of the suspension-wire systems 39 and 54 in an appropriate manner until the suction tube inlet 17 reaches the seabed 18.

[0124] Hereby, before actually unfolding the articulated pumping line 8, the pumping line 8 is descended from deck level to under water level by unwinding the wires 42, 44, 46, 49 and 52 of the pumping line vessel-side part suspension-wire system 39 and the wire 56 of the pumping line extension part suspension-wire system 54 simultaneously and all more or less at the same speed, so that the pumping line 8 is kept in the reduced status and is kept parallel with the deck 6.

[0125] Meanwhile, the second extremity 19 of the pumping line 8 is slid in the trunnion slide guide 22, until the bottom 24 of the hull is reached, after which the discharge tube 11 of the pumping means 7 is connected to a discharge pipe in the hull 3 of the vessel 2.

[0126] This is the situation as represented in figure 2.

[0127] Then, the articulated pumping line 8 is unfolded into the extended status, which requires at least the following steps.

[0128] In a first step the concerned wires of the pumping line vessel-side part suspension-wire system 39 are unrolled, i.e. wires 42, 44, 46 and 49, but not wire 52 of the fifth hoisting means 51.

[0129] During unrolling of these wires 42, 44, 46 and 49 each wire 42, 44, 46 and 49 is unrolled at a controlled speed such that the pumping line vessel-side part 27 rotates downwards around the trunnion slide connection 20, the different pumping line vessel-side part sections 32 to 34 being kept approximately in line.

[0130] At the same time also the wire 56 of the pumping line extension part suspension-wire system 54 is unrolled however at a much higher speed than the speed by which wire 46 of the third hoisting means 48 in order to obtain a rotation of the pumping line extension part 28 with respect to the pumping line vessel-side part 27.

[0131] The unrolling of all the concerned wires, i.e. 42, 44, 46, 49 and 56, of the pumping line vessel-side part suspension-wire system 39 and the pumping line extension part suspension-wire system 54 is continued until the pumping line extension part 28 is oriented in an approximately vertical position and the suction tube inlet 17 is a few meters above the seabed level 18.

[0132] In a last step during unfolding of the articulated pumping line 8 the suction tube inlet 17 is carefully lowered until the seabed 18 is reached by further unwinding the corresponding wires of the pumping line vessel-side part suspension-wire system 39 and the pumping line extension part suspension-wire system 54, i.e. wires 42, 44, 46, 49 and 56, each at a speed for realizing a downward vertical movement of the pumping line 8.

[0133] The final situation obtained is illustrated in figure 5.

[0134] At that moment the dredging or mining operation at the concerned area can be started, by starting the submergible pump 10 and a jet-water pump for pumping water through the water-jet pipe 25.

[0135] As a consequence, a mixture of water and seabed material 18, which is loosened by water ejected through the nozzles 26 of the water-jet pipe 25, is pumped by the submergible pump 10 into the vessel 2.

[0136] According to a preferred method in accordance with the invention the dredging or mining process is hereby monitored by a position and depth controller which receives input from a sensor or sensors mounted on the suction tube inlet 17.

[0137] The dredging or mining process is preferably at the same time also monitored by production-control gauges.

[0138] Such production-control gauges can for example be a differential pressure gauge, a mixture-velocity gauge, a concentration gauge or a density gauge, or any production-control gauge combination or any other type of production-control gauge.

[0139] After dredging, when the hopper-load is filled or when the load capacity of the vessel 2 is reached, the reverse-operation is initiated, whereby the articulated pumping line 8 is folded again into a reduced status and brought back into the onboard position for storing it on board of the vessel 2.

[0140] For bringing the pumping means 7 into the onboard position at least the following steps are executed according to the invention.

[0141] First, the suction tube inlet 17 is lifted from the seabed 18 by winding the wires of the concerned suspension-wire systems 39 and 54 simultaneously, i.e wires 42, 44, 46, 49 and 56 each, at a speed corresponding with a vertical translational movement of the pumping line 8.

[0142] Then, the pumping line 8 is flushed with seawater, after which the wires 42, 44, 46 and 49 of the pumping line vessel-side part suspension-wire system 39 and the wire 56 of the pumping line extension part suspension-wire system 54 are further wound.

[0143] Hereby, the wires 46 and 56 of the mid-ship pumping line suspension wire system 58 are wound at a considerably different speed, i.e; wire 56 is wound at a higher speed, for example at double speed compared to the speed by which wire 46 is wound.

[0144] In that way the pumping line extension part 28 rotates towards the pumping line vessel-side part 27 into the reduced status, i.e. into parallel with one another.

[0145] Once the pumping line 8 is in the reduced status- winding the wires 42, 44, 46 and 49 of the pumping line vessel-side part suspension-wire system 39 and the wire 56 of the pumping line extension part suspension-wire system 54 are again wound simultaneously, the different sections 28, 32 to 34 of the articulated pumping line 8 being rotated in the reduced status around the trunnion slide connection 20 until the pumping line 8 reaches the lower level 24 of the vessel 2.

[0146] At that moment the discharge tube 11 of the pumping line 8 is disconnected from the discharge pipe in the hull 3 of the vessel 2 and the pumping line 8 is moved upwards from the under water level to deck level by winding the concerned wires of the involved suspension-wire systems, i.e wire 42, 44, 46, 49, as well as wire 52 and wire 56, all at the same speed.

[0147] Hereby the second extremity 19 of the pumping line 8 is slid upwards in the trunnion slide guide 22, the pumping line 8 in the reduced status being kept parallel with the deck 6.

[0148] The whole pumping line 8 is flushed gravitationally during this hoisting above-water and subsequently lifted on-board and laid-down in its cradles.

[0149] This situation corresponds again to the original situation wherein the pumping line 8 is stored onboard of the vessel 2, as is represented in figure 1.

[0150] In an alternative method wherein the dredger loads barges, the dredging process is not discontinued till the barge is filled.

[0151] Upon completion of the dredging the dredger sails to its upland or aquatic disposal facility where the dredge material is off-loaded by hydraulic pumping, by dumping or by mechanical unloading as the case may be.

[0152] In case of emergency an emergency-hoisting system with preinstalled wires on the suction-tube is used to recover the suction-tube.

[0153] The present invention is by no means limited to the embodiment of dredging equipment 1 according to the invention described as an example and illustrated in the drawings, but dredging equipment 1 according to the invention can be realised in all kinds of variants, without departing from the scope of the invention.

[0154] The present invention is also by no means limited to the method for dredging or mining according to the invention described as an example and illustrated in the drawings, but such a method according to the invention can be realised in all kinds of variants, without departing from the scope of the invention.

Claims

1. Dredging equipment (1) which comprises at least:

- a vessel (2);

- pumping means (7); and,

- one or more suspension-wire systems (39,54) on the vessel (2) each with hoisting means (40,45,48,51,55) for winding and unwinding one or more wires (42,44,46,49,52,56) which are linked to the pumping means (7); the pumping means (7) comprising at least:

- a pumping line (8), which consists of a suction tube (9), a submergible pump (10) and a discharge tube (11);

- an inlet (12) of the submergible pump (10) which is connected to a first extremity (13) of the suction tube (9) and an outlet (14) of the submergible pump (10) which is connected to a first extremity (15) of the discharge tube (11);

- a second extremity (16) of the suction tube (9) being a free end forming a suction tube inlet (17) for sucking a mixture of water and loosened seabed material (18);

- a trunnion slide connection (20) of the pumping line (8) with the vessel (2) at the second extremity (19) of the discharge tube (11), which is such that the pumping line (8) can be moved between an onboard position for storing the pumping line (8) on board of the vessel (2) and a submerged position outboard the vessel (2) and beneath the water level (21) for use of the pumping line (8) ;

characterized in that the pumping line (8) is an articulated pumping line (8) comprising two or more pumping line sections (28,32,33,34), adjacent pumping line sections being connected to one another in a rotatable manner by means of an articulation (31,36,38), different parts of the pumping means (7) being linked to a wire or to wires (42,44,46,49,52,56) of an above-mentioned suspension-wire system (39,54) in such a way that, on the one hand, by winding the concerned wires the articulated pumping line (8) can be folded into a reduced status with reduced dimensions and be brought in the onboard position, in which reduced status at least some of the pumping line sections (28, 32,33) are brought parallel and near to one another over a substantial part of their length, and, on the other hand, by unwinding the concerned wires of the articulated pumping line (8) can be unfolded into an extended status with extended dimensions and be brought in the submerged position for use of the pumping means (7), in which extended status the pumping line sections (28,32,33,34) are distant from one another except at their interconnection by means of the concerned articulation (31,36,38).

2. Dredging equipment (1) according to claim 1, characterized in that the articulated pumping line (8) comprises a pumping line vessel-side part (27) and a pumping line extension part (28) connected to one another in a rotatable manner at a first of their extremities (29,30) by means of a first articulation (31), the pumping line vessel-side part (27) being provided at its second extremity (19) with said trunnion slide connection (20) of the pumping means (7) with the vessel (2) and being suspended with respect to the vessel (2) at least partly by means of the wire or wires (42,44,46,49,52) of a pumping line vessel-side part suspension-wire system (39), and the pumping line extension part (28) having at its second extremity (16) a free end forming the suction tube inlet (17) and being suspended at least partly to the vessel (2) by means of the wire (56) or wires of a pumping line extension part suspension-wire system (54).

3. Dredging equipment (1) according to claim 2, characterized in that the wire (56) or wires of the pumping line extension part suspension-wire system (39) is or are linked with one end to the suction tube inlet (17) and is or are partly wound at a second end on a winch on the deck (6) of the vessel (2), while the concerned wire (56) or wires passes or pass from the winch over a gantry on the deck (6) and further over a roller cage (57) which is fixed to the pumping line vessel-side part (27).

4. Dredging equipment according to claim 2 or 3, characterized in that the pumping line vessel-side part has a length (L) which approximately corresponds to the length (M) between the position of the trunnion slide connection (20) of the pumping means (7) with the vessel (2) and the stern (5) of the vessel (2).

5. Dredging equipment (1) according to any of claims 2 to 4, characterized in that the pumping line extension part (28) consists of a single rigid suction tube section (28) without any further articulation, apart from the first articulation (31).

6. Dredging equipment (1) according to any of claims 2 to 5, characterized in that the pumping line vessel-side part (27) is composed of multiple pumping line vessel-side part sections (32-34) and in that adjacent pumping line vessel-side part sections are connected to one another in a rotatable manner by an articulation (36,38).

7. Dredging equipment (1) according to claim 6, characterized in that each pumping line vessel-side part section (32-34) is at least suspended by a separate wire or a separate set of wires (42, 44, 46, 49) of the pumping line vessel-side part suspension-wire system (39), the separate wire or separate set of wires (42,44,46,49,52) being linked to the concerned pumping line vessel-side part section (32-34) in the vicinity of an articulation (31,36,38) at the side of the concerned pumping line vessel-side part section (32-24) which is the most distant from the vessel (2).

8. Dredging equipment (1) according to claim 7, characterized in that an extremity of each said separate wire or set of separate wires (42,44,46,49) of each pumping line vessel-side part section (32-34) is or are wound on a corresponding separate winch of the pumping line vessel-side part suspension-wire system (39) provided on the vessel (2) and passed over a corresponding separate gantry on the vessel (2).

9. Dredging equipment (1) according to any of claims 6 to 8, characterized in that the pumping line vessel-side part (27) consists of three pumping line vessel-side part sections (32-34):

- a top pumping line vessel-side part section (32) connected in a rotatable and movable manner with an extremity (19) to the vessel (2) by means of the trunnion slide connection (20);

- a bottom pumping line vessel-side part section (33) connected in a rotatable manner with an extremity (29) by means of the first articulation (31) to the pumping line extension part (28);

- an intermediate pumping line vessel-side part section (34) mounted in a rotatable manner, on the one hand, at its first extremity (35) to the bottom pumping line vessel-side part section (33) by means of a second articulation (36), and on the other hand, at its second extremity (37) to the top pumping line vessel-side part section (32) by means of a third articulation (38).

10. Dredging equipment (1) according to any of the preceding claims, characterized in that the pumping line (8) is provided with a water-jet pipe (25) mounted along the pumping line (8) and having an articulation in the vicinity of each articulation (31,36,38) of the pumping line (8).

11. Dredging equipment (1) according to any of the preceding claims, characterized in that at least one of the articulations (36,38) is a cardan coupling, allowing a limited rotation of the adjacent pumping line sections (32-34).

12. Dredging equipment (1) according to claims 6 and 11, characterized in that all the articulations (36,38) provided between pumping line vessel-side part sections (32-24) are cardan couplings.

13. Dredging equipment (1) according to any of the preceding claims, characterized in that at least one or more of the articulations (31) is a swivel coupling, allowing a rotation over 360° of the adjacent pumping line sections (28,33).

14. Dredging equipment (1) according to claims 2 and 13, characterized in that the first articulation (31) is a swivel coupling.

15. Dredging equipment (1) according to any of claims 2 to 14, characterized in that first hoisting means (40) are provided having a wire (42,44) or a set of wires (46) which is or are linked to the pumping line vessel-side part (27) in the vicinity of or on the first articulation (31), which first hoisting means (40) form a part of the pumping line vessel-side part suspension-wire system (39).

16. Dredging equipment (1) according to claim 15, characterized in that the first hoisting means (40) are provided in the vicinity of the stern (5) of the vessel (2), forming an aft ship pumping line suspension-wire system (40).

17. Dredging equipment (1) according to claims 2 and 9, characterized in that second hoisting means (45) are provided having a wire (46) or a set of wires which is or are linked to the intermediate pumping line vessel-side part section (34) in the vicinity of or on the second articulation (36), which second hoisting means (45) form a part of the pumping line vessel-side part suspension-wire system (39).

18. Dredging equipment (1) according to claims 3 and 17, characterized in that the second hoisting means (45) and the pumping line extension part suspension-wire system (54) are provided approximately at half of the length of the vessel (2), forming together a mid-ship pumping line suspension-wire system (58).

19. Dredging equipment (1) according to claims 2 and 9, characterized in that third hoisting means (48) are provided having a wire (49) or a set of wires which is or are linked to the top pumping line vessel-side part section (32) in the vicinity of or on the third articulation (38), which third hoisting means (48) form a part of the pumping line vessel-side part suspension-wire system (39).

20. Dredging equipment (1) according to any of claims 2 to 19, characterized in that fourth hoisting means (51) are provided having a wire (52) or a set of wires which is or are linked to the second extremity (19) of the pumping line (8) at the trunnion slide connection (20), which fourth hoisting (51) means form a part of the pumping line vessel-side part suspension-wire system (39).

21. Dredging equipment (1) according to claim 20, characterized in that an elongated trunnion slide guide (22) is provided along a sidewall (23) of the hull (3) of the vessel (2) from the bottom (24) to the deck (6), in which trunnion slide guide (22) the second extremity (19) of the discharge tube (11), on the one hand, can rotate around an axis which is perpendicular to the concerned sidewall (23), and, on the other hand, can move upwards and downwards along the concerned sidewall (23) of the hull (3) between a downward position for connection to a discharge pipe mounted inside the hull (3) and an upward position in the vicinity of the deck level of the vessel (2), by winding respectively unwinding a wire or wires of the fourth hoisting means (51).

22. Dredging equipment (1) according to any of the preceding claims, characterized in that it comprises one or more suspension-wire systems (39,54) provided with a heave compensator.

23. Dredging equipment according to any of the preceding claims, characterized in that the suction tube inlet (17) is provided with a shock absorber (59) which comprises two concentric telescopic pipes, i.e. an inner pipe and an outer pipe, and a spring (60) mounted between the telescopic pipes which is compressed when the inner pipe is pushed into the outer pipe.

24. Dredging equipment (1) according to claim 9, characterized in that the top pumping line vessel-side part section (32) and the intermediate pumping line vessel-side part section (34) are steel tube sections.

25. Dredging equipment (1) according to claim 9, characterized in that the bottom pumping line vessel-side part section (27) and the pumping line extension part (28) consist of one or more plastic pipes which are provided in a metal lattice girder (62).

26. Dredging equipment (1) according to any of the preceding claims, characterized in that the pumping line (8) is provided with one or more vacuum relief valves (61).

27. Dredging equipment (1) according to any of the preceding claims, characterized in that the suction tube inlet (17) is provided with sensors for measuring the position of the suction tube inlet (17) with respect to the vessel (2) and which provide an input for a controller which controls the position of the suction tube inlet by means of the suspension-wire systems (39,54).

28. Dredging equipment (1) according to claim 27, characterized in that a wire or wires of the suspension-wire systems (39,54) are provided with an interactive wire-tensioning control system by which the tension in the corresponding wires is kept within certain limits.

29. Method for dredging or mining with dredging equipment (1) according to claim 1, characterized in that the method comprises at least the following steps:

- sailing the vessel (2) towards an area to be dredged or mined the pumping line (8) being in a reduced status;

- unwinding wires (42,44,46,49,52,56) of the suspension-wire systems (39,54) for bringing the pumping means (7) into a submerged position and unfolding the articulated pumping line (8) into an extended status until the suction tube inlet (17) reaches the seabed (18);

- dredging or mining the concerned area by pumping a mixture of seabed material (18) and water into the vessel (2) or into a barge; and,

- winding wires (42,44,46,49,52,56) of the suspension-wire systems (39,54) for folding the articulated pumping line (8) into a reduced status and bringing the pumping means (7) in the onboard position for storing it on board of the vessel (2) after dredging or when the load capacity of the vessel (2) is reached.

30. Method for dredging or mining according to claim 29 with dredging equipment according to claim 21, characterized in that, before unfolding the articulated pumping line (8), the method comprises at least the following steps:

- descending the pumping line (8) from deck level to under water level (21) by unwinding the wires (42,44,46,49,52,56) of the pumping line vessel-side part suspension-wire system (39) and the pumping line extension part suspension-wire system (54) simultaneously at the same speed, the pumping line (8) being kept in the reduced status and being kept parallel with the deck (6), and the second extremity (19) of the pumping line (8) being slid in the slide guide (22); and,

- connecting the discharge tube (11) of the pumping means (7) to a discharge pipe in the hull (3) of the vessel (2).

31. Method for dredging or mining according to claim 29 or 30 with dredging equipment (1) according to claim 2, characterized in that the unfolding of the articulated pumping line (8) comprises at least the following steps:

- unrolling the concerned wire or wires (42,44,46,49,56) of the suspension-wire systems (39,54) each at a speed such that the pumping line vessel-side part (27) rotates downwards around the trunnion slide connection (20), the different sections (32-34) of the pumping line vessel-side part (27) being kept approximately in line; the wire (56) or wires of the pumping line extension part suspension-wire system (54) at a higher speed in order to obtain a rotation of the pumping line extension part with respect to the pumping line vessel-side part (27);

- continuing unrolling the concerned wires (42,44,46,49,56) of the pumping line vessel-side part suspension-wire system (39) and the pumping line extension part suspension-wire system (54) until the pumping line extension part (28) is oriented in an approximately vertical position and the suction tube inlet (17) is a few meters above the seabed level (18); and,

- lowering the suction tube inlet (17) carefully until the seabed (18) is reached by further unwinding the corresponding wires (42,44,46,49,56) of the pumping line suspension-wire systems (39,54).

32. Method for dredging or mining according to any of claims 29 to 31, characterized in that the dredging or mining process is monitored by a position and depth controller which receives input from a sensor or sensors mounted on the suction tube inlet (17).

33. Method for dredging or mining according to any of claims 29 to 32, characterized in that the dredging or mining process is monitored by production-control gauges.

34. Method for dredging or mining according to claim 27, characterized in that the production-control gauges comprise one or more of the following types of gauges:

- a differential pressure gauge;

- a mixture-velocity gauge;

- a concentration gauge; and,

- a density gauge.

35. Method for dredging or mining according to any of claims 29 to 34 with dredging equipment according to claim 21, characterized in that for bringing the pumping means (7) into the onboard position the method comprises at least the steps of;

- lifting the suction tube inlet (17) from the seabed (18) by winding the wires (42,44,46,49,56) of the concerned suspension-wire systems (39,54) simultaneously;

- flushing the suction tube (9) with seawater;

- winding the wires (42,44,46,49,56) of the pumping line vessel-side part suspension-wire system (39) and the pumping line extension part suspension-wire system (54), the speed at which the wire (56) or wires of the pumping line extension part suspension-wire system is or are wound being higher in order to rotate the pumping line extension part (28) towards the pumping line vessel-side part (27) into the reduced status;

- winding the wires (42,44,46,49,56) of the pumping line vessel-side part suspension-wire system (39) and the pumping line extension part suspension-wire system (54) simultaneously, when the pumping line extension part (28) has been brought into parallel with the pumping line vessel-side part (27), the different sections (32-34) of the articulated pumping line (8) being rotated in the reduced status around the trunnion slide connection (20) until the pumping line (8) reaches the lower level (24) of the vessel (2);

- disconnecting the discharge tube (11) of the pumping line (8) from the discharge pipe (11) in the hull (3) of the vessel (2); and

- moving the pumping line (8) upwards from under water level to deck level winding the concerned wires (42,44,46,49,52,56) of the involved suspension-wire systems (39,54) in order to slide the second extremity (19) of the pumping line (8) upwards in the trunnion slide guide (22), the pumping line (8) being kept in the reduced status and being kept parallel with the deck (6).

Drawing