Very large sand carrier and method for delivering dry sand over large distances

Abstract

Method for delivering sand to a work site, wherein sludge comprising sand and water is dredged at a dredging site and the sludge is loaded directly into a transport vessel, where after the transport vessel sails to a delivery site, wherein the vessel is a vessel having a high loading capacity, the sludge being loaded into the vessel while the sludge has a high moisture content, wherein during sailing of the vessel to the delivery site process water is discharged from the vessel, reducing the moisture content of the sludge for obtaining dry sand, and limiting the draft of the vessel, where after at the delivery site the sand is discharged from the vessel in dry condition.

Description

[0001] Title: Very large sand carrier and method for delivering dry sand over large distances

[0002] The invention relates to a method and vessel for delivery of sand over long distances. The invention relates to a method and vessel for transporting sand from a dredging site to a delivery or discharge site at a long distance from the dredging site.

[0003] EP2 141288 discloses a method for delivering large quantities of sand over long distances, wherein the sand is dredged at a dredging site and delivered to a dehvery site a long distance away from the dredging site. In EP2 141288 long distances are defined as over 500 km single sailing distance. In a method according to EP2141288 dredged sludge is loaded into a vessel, wherein the sludge is dried to a transportable moisture limit prior to loading it into the transport vessel. Only then does the vessel sail to the discharge site, at which the sand can be discharged dry. This method provides for a high loading capacity of dry sand, but this is time consuming which reduces efficiency of the method. In an alternative method in EP2 141288 the dredged sludge is loaded into the vessel with a water content of more than 20% of the total weight of the dredged soil, for example between 20% and 35%. In this method the soil can be loaded into the vessel hydraulically, requiring less time. The dredged sludge is transported to the discharge site with this high water content, and is discharged, again hydraulically. In this method the loading capacity for the sand is limited because of the high water content, whereas discharge is only possible at locations with a relatively large water depth, because of the draft of the very large vessel loaded to its loading capacity. These methods are therefore not economical.

[0004] There is therefore a need for a method for delivering sand over long distances which is more efficient and more practical. An aim of the present disclosure is to provide for an alternative method for delivering sand over long distances. An aim of the present disclosure is to provide for a method of delivering large quantities of sand over long distances, which method is economical. An aim of the present disclosure is to provide for a method for delivering sand over long distances, which also allows discharge of sand at hard to reach destinations. An aim of the present disclosure is to provide for a method in which time delay for loading and unloading is reduced. An aim of the present disclosure is to provide for a vessel for transporting large quantities of sand over long distances. An aim is to provide a vessel for transporting large quantities of sand over long distances, in an economical manner, wherein the vessel can be used for discharging transported sand at various locations.

[0005] At least one of these and other aims are obtained with a method and / or vessel according to the disclosure.

[0006] In an aspect a method of the disclosure for delivering sand to a work site sludge comprising sand and water is dredged at a dredging site and the sludge is loaded into a transport vessel. Thereafter the transport vessel sails to a delivery site. The transport vessel is a vessel having a high loading capacity and the sludge is loaded directly into the vessel while the sludge has a high moisture content. During sailing of the vessel to the delivery site water is discharged from the vessel, reducing the moisture content of the sludge for obtaining dry sand, and limiting the draft of the vessel. At the delivery site the sand is then discharged from the vessel in dry condition.

[0007] With a method according to the disclosure the vessel can be loaded quickly at the dredging site. This reduces the time the vessel has to be stationary. The very large vessel can for example preferably be loaded within a period of less than 48 hours, for example within 24 hours, such that the vessel can start sailing quickly after loading has completed. In embodiments the vessel may be loaded to full capacity with the sludge, which dredged sludge may have a water content of over 35% in weight of the total weight of the dredged sludge. In such embodiments there is no need for double handling of the sludge or for a drying step or even a draining step prior to loading.

[0008] Preferably the sludge is dredged and fed into the vessel hydraulically, using pumping equipment. To this end the vessel is preferably equipped with dredging equipment, such as for example dredging equipment for suction dredging as known in the art, for example for trailing suction dredging or stationary suction dredging. By using dredging equipment of the vessel there is no need for additional equipment, such as for example separate dredging vessels, transport vessel, drying equipment, buffering equipment or the like. This will reduce cost and will reduce time that the vessel has to be at the dredging site.

[0009] During loading of the sludge into the vessel effluent water may be discharged directly back into the water at the dredging site, for example through overflows, as known in the art. The effluent water may be discharged actively and / or passively. Discharging of the effluent can be obtained in any suitable way, such as for example by an overflow or by using a discharge pump.

[0010] During sailing water is drained from the sludge, which will be discharged from the vessel, reducing the total volume of cargo, and at the same time reducing the draft of the vessel considerably. This means that the vessel can sail to discharge locations having a water depth which is smaller than the draft of the vessel directly after loading. At the discharge location the dried sand is then discharged directly from the vessel into the water surrounding the vessel. Preferably the sand is discharged from the vessel directly into a work site forming the discharge site. At such discharge site the water depth may be limited, for example less than the draft of the vessel directly after loading. The water depth can for example be but is not limited to less than 18 meters, for example less than 16 meters, such as less than 15 meters. The draft of the vessel directly prior to discharge of the sand can for example be, but is not limited to, less than 16 meters, such as for example less than 15 meters, whereas the draft of the vessel directly after loading to full capacity is more than such draft directly prior to discharge, for example but not limited to more than 18 meters. .

[0011] In an aspect of the disclosure a method comprises the sand being discharged from the vessel using a dry sand discharge system provided on the vessel. The sand is preferably discharged over a board, bow or side of the vessel. This should be understood as meaning that the sand is preferably discharged from the vessel at a level above the level of water into which it is discharged.

[0012] During sailing of the vessel from the dredging site to the discharge site water is drained from the sludge, reducing the water content and thus volume of the sludge, which will thus become dry sand. The water is drained from the sand and collected for example at a level below a top of the sludge, for example near the bottom of the vessel, and is preferably treated prior to being discharged into water surrounding the vessel while sailing. For treating the water a ballast water treatment system can be used, as known in the art, for example a ballast water treatment system of the vessel. By treating the water prior to discharging it is prevented that invasive species are discharged into the surrounding water, which invasive species may have been dredged with the sludge at the dredging site. These invasive species may be retained by the treatment equipment and discarded later in a proper manner.

[0013] In embodiments of a method of the disclosure as a vessel a converted ore carrier can be used, such as for example a converted very large ore carrier, for example converted for shipping high moisture dredging sludge, discharging effluent during sailing and for discharging dry sand mechanically.

[0014] A vessel used in a method according to the disclosure can have a single hold. Preferably the vessel has a series of holds, provided for example in one or more rows in the hull of the vessel. From the or each hold the water is discharged away from the vessel through one or more discharge point, such that during sailing of the vessel in the or each hold the process water drained from the sludge is discharged, reducing the volume of material in the or each hold significantly and at the same time reducing the draft of the vessel too. As discussed in some preferred embodiments surprising use is made of such reduction in draft by sailing the vessel, for discharging of the sand, into waters having a smaller water depth than the original draft of the vessel when loading.

[0015] It has been found that even though with a method according to the disclosure a smaller amount of dry sand is transported and discharged than when a similarly sized vessel is used for shipping sand with a method according to EP 141288, per sailing trip to the discharge area, a method according to the disclosure is nevertheless more economical. One important factor in this is the shorter time necessary for loading and the possibility of directly discharging the sand into a work site having a limited water depth.

[0016] In advantageous embodiments the vessel sails to the discharge location with any hold of the vessel containing sludge open at an upper side. The hold or holds therefore need not be provide with closures such as lids or hatches or shutters or the like, reducing weight of the vessel and time necessary for loading and / or discharging of the sand.

[0017] In an aspect the present invention can be characterized by a transport vessel comprising at least one hold for holding sludge, the sludge comprising sand, wherein the vessel has a loading capacity of over 100.000 cubic meters of sludge or over 200.000 tons of sludge. The vessel has at least one water discharge for discharging process water from the at least one hold, wherein the at least one discharge has at least one water inlet side which is provided below an upper side of said at least one hold. With such vessel during sailing water, also referred to as process water, can be removed from the sludge and be discharged from the vessel, drying the sand and at the same time reducing the draft of the vessel during sailing. Preferably the vessel is designed to discharge effluent during loading of sludge into the vessel.

[0018] The vessel preferably comprises dredging equipment for hydraulic dredging and loading of the vessel, such as suction dredging equipment. The suction dredging equipment may for example be trailing suction dredging equipment, stationary suction dredging equipment or other suitable dredging and hydraulically loading dredging equipment as known in the art.

[0019] In preferred embodiments the vessel comprises a discharge system for discharge of dry sand from the at least one hold of the vessel. Such discharged system is designed for discharging the dry sand in dry condition, that is discharging mechanically.

[0020] The discharge system can comprise at least one transport track extending in a longitudinal direction of the vessel alongside said at least one hold, and rails extending in the longitudinal direction of the vessel, wherein at least one crane is supported on said rails, such that said crane can move over said at least one hold, for lifting sand from said hold and deposing of said sand onto the at least one transport track. The or each crane can for example comprise a portal crane movable over said at least one hold or a crane having a pivoting crane, comprising an arm which is movable over such hold, to lift material from said hold or holds.

[0021] The at least one transport track can be provided at a deck of said vessel, and can connect to a transfer system for transferring the sand from the transport track to a point outside the vessel, for discharging the sand from the vessel into water below said point. Providing the transport system, especially the at least one transport track at a deck of the vessel can have the advantage of easy conversion of a vessel to be suitable for use in a method according to the present invention.

[0022] A vessel according to the disclosure can have at least an inner shell and an outer shell and ballast tanks. The ballast tanks can be used for improving stability during transport and / or can be used for adapting the draft of the vessel. As discussed, ballast tanks can be provided with ballast water treatment equipment for treating, especially filtering ballast water when being discharged from the ballast tanks, which ballast water treatment equipment can in advantageous embodiments according to the disclosure also be used for treating, especially filtering, of process water before being discharged during sailing.

[0023] In advantageous embodiments according to the disclosure the vessel can have a maximum loading capacity for dredged sludge of at least 50.000 cubic meters, preferably at least 75.000 cubic meters, such as for example 100.000 cubic meters or more. The vessel in such embodiments, when loaded with dry sand which is obtained by loading the vessel to the maximum loading capacity with dredged sludge and removing process water from the vessel, preferably has a draft of less than 16 meters, preferably less than 14,5 meters, such as for example a draft of between 13 and 15 meters, more preferably between 13,5 and 14,5 meters, whereas the draft, when fully loaded with said dredged sludge, is for example 18 to 19 meters.

[0024] For a better understanding of the disclosure embodiments of a method, system and anchor according to the disclosure will hereafter be described, by way of example only, with reference to the drawings. Therein shows schematically:

[0025] Fig. 1 in perspective view an embodiment of a vessel according to the disclosure;

[0026] Fig. 2 in perspective view a further embodiment of a vessel according to the disclosure;

[0027] Fig. 3 in top view a vessel of fig. 2;

[0028] Fig. 3A in top view an enlarged part of figure 3;

[0029] Fig. 4 in cross sectional side view a first embodiment of a vessel of the disclosure; Fig. 5 in top view a deck of a vessel according to the first embodiment;

[0030] Fig. 6 in cross sectional view along the line VI - VI in fig. 4 the vessel according to the first embodiment, wherein on the left hand side a partially filled cargo hold is shown, and on the right hand side a substantially empty cargo hold;

[0031] Fig. 7 A - C three steps during unloading of the vessel for discharge of sand therefrom;

[0032] Fig. 8 in cross sectional side view a second embodiment of a vessel of the disclosure;

[0033] Fig. 9 in top view a deck of a vessel according to the second embodiment;

[0034] Fig. 10 in cross sectional view along the line X - X in fig. 8 the vessel according to the second embodiment, with a hold partly filled with dry sand;

[0035] Fig. 11 in cross sectional side view a third embodiment of a vessel of the disclosure;

[0036] Fig. 12 in top view a deck of a vessel according to the third embodiment;

[0037] Fig. 13 in cross sectional view along the line XIII - XIII in fig. 11 the vessel according to the third embodiment, wherein on the left hand side a partially filled cargo hold is shown, and on the right hand side a substantially empty cargo hold;

[0038] Fig. 14 in cross sectional view according to for example fig. 4, 8 or 11, a vessel with dredging equipment and ballast tanks and water treatment equipment, in an embodiment;

[0039] Fig. 15 a vessel according to the disclosure, on the left hand side at a dredging site and at the right hand side at a discharge site;

[0040] Fig. 16 shows schematically a dredging system suspended from a side of the vessel; Fig. 17 an image of part of a load in a cargo hold, such as a hopper of a dredger or barge;

[0041] Fig. 18 a cargo hold such as for example shown in any one of the previous figures, showing part of a volumetric measuring system; and

[0042] Fig. 19 an image generated by the volumetric measurement system, used for assessing a volume of material stored in a cargo hold.

[0043] It should be noted that these drawings are schematic, not to scale and are provided for a better understanding of the disclosure. The embodiments shown in the drawings and described hereafter are shown only by way of example and should not be considered limiting the scope of the disclosure. In the description the same or similar reference signs will refer to the same or similar features.

[0044] The disclosure is directed to vessels and methods for dredging, transport over long distances and discharging of sand. In this disclosure sand should be understood as a material or mixture of materials having a granular size of between 0.06 and 2 mm, wherein sand may also comprise a limited volume percentage of gravel, having a granular size of between 2 and 60 mm, and particles smaller than 0.06 mm. In this disclosure dry sand should be understood as sand having a low moisture content, especially a moisture content significantly lower than when hydraulically loading sludge comprising said sand. Dry sand can for example have a moisture content of 15% by weight or less, for example a moisture content of 10% or less, and can have upward from 80% in volume material with a granular size between 0.06 and 2 mm. In this disclosure sludge should at least be understood as meaning a mixture of water, especially sea water, and sand, which mixture can be dredged by suction and can be hydraulically loaded into a vessel, especially by pumping. Sludge dredged and loaded into the vessel may at the start of sailing away from the dredging site for example have a weight of about 2.0 T / m3or more (metric ton per cubic meter), whereas during sailing of the vessel and in a method according to the disclosure the water content can be reduced such that the dry sand upon discharging has a weight significantly lower than said about 2.0 T / m3such as for example of about 1.75 T / m3or less.

[0045] In this disclosure a very large vessel should be understood as a vessel having a very large loading capacity, for example a loading capacity of 50.000 cubic meters (m3) and / or of over 100.000 metric tons. A vessel according to the disclosure can have a loading capacity of 100.000 cubic meters and / or 200.000 tons. In embodiments of the disclosure the vessel can be a very large ore carrier (VLOC) adapted for transporting dredged sludge and sand according to the disclosure. In this disclosure a long distance should be understood as meaning a distance of over 500km single sailing distance. A long distance can for example be a distance of over 500 nautical miles (Nm) single sailing distance, wherein 1 nautical mile is 1.85200 kilometer.

[0046] In this disclosure wording like about and substantially should be understood as meaning that slight variations of a characteristic to which it refers are allowable, for example variations of less than 10%, such as less than 5% of an value of such characteristic.

[0047] In this disclosure TML should be understood as Transportable Moisture Limit, as known in the art.

[0048] In this disclosure vessels 1 are shown and discussed which are, as described, very large vessels, having very large loading capacities, unless specifically discussed otherwise.

[0049] Fig. 1 shows a rendering of a vessel 1 according to the disclosure, suitable for use in a method of the disclosure, as will be discussed. The vessel 1 is in this embodiment shown as a bulk carrier, such as for example a very large ore carrier (VLOC) as known in the art, adapted for transporting sludge 2, and for dredging sludge 2 from a water bedding B. The vessel 1 has a hull 3 and a deck 4, with accommodations 5 for personnel and equipment, in a known manner. In the hull 3 a series of cargo holds 6 is provided, accessible through openings 7 in the deck 4, which are shown in fig. 1 as being closed by hatches 8. In embodiments the holds 6 can be open while sailing the vessel 1, which reduces weight of the vessel and handling during loading and unloading.

[0050] In the embodiment shown in fig. 1 the vessel has eight holds 6 but obviously other numbers of holds can be provided, for example a single hold 6 or a series of any number of such holds 6. In this embodiment the holds 6 are shown as provided in a single row, but obviously holds can also be provided in two or even more rows, for example next to each other, as for example shown in fig. 2 and 3.

[0051] In fig. 1 the vessel 1 is provided with dredging equipment 9, schematically shown by a dredging pipe 10 of a suction dredging system as known in the art, which has, as for example shown e.g. in fig. 4 - 5, 8 - 9, 14 and 15, a suction pipe 11, which at a lower end connects to a suction head 12 and is provided with a pump 13 (fig. 14) for hydraulically dredging sludge 2 and forwarding the sludge through the suction pipe into the vessel 1, to be loaded in the holds 6. The sludge can be pumped by the pump 13 and / or can be sucked through the pipe 11 by creating a pressure in the suction head and suction pipe below atmospheric, as is known in the art of suction dredging, for example trailing suction dredging. In this embodiment the suction pipe or pipes 11 is provided at the port side of the vessel 1, by way of example only. Any suitable type and configuration of dredging equipment can be provided, in any suitable position as known in the art.

[0052] Furthermore the vessel 1 is provided with lifting equipment such as cranes 14, 15, which can be used for example for lifting the dredging equipment and can be used as or in a discharge system 16 for discharge of dry sand from the at least one hold of the vessel, including for unloading the dry sand from the holds 6, as will be discussed. The vessel 1 is designed for dredging sludge and transporting said sludge over long distances, wherein during transport water is drained from the sludge 2, such that the sludge transforms into relatively dry sand, having a significantly lower water content than the sludge as loaded.

[0053] Fig. 2 and 3 show in perspective and top view another embodiment of a vessel 1 for dredging sludge and transporting said sludge over long distances, wherein during transport water is drained from the sludge 2, such that the sludge transforms into relatively dry sand, having a significantly lower water content than the sludge when loaded.

[0054] In the embodiment of fig. 2 and 3 the vessel 1 has eight holds 6, provided in two parallel rows of four holds 6 each. In this embodiment the accommodation 5 is primarily provided mid-vessel, by way of example, with four holds 6 in front of and four holds 6 behind said accommodation 5. In this embodiment no hatches are provided or at least shown.

[0055] In this embodiment again the vessel 1 comprises a discharge system 16 for discharge of dry sand 17 from the at least one hold 6 of the vessel 1. In this embodiment the discharge system 16 comprises at least one transport track 18 extending in a longitudinal direction L of the vessel 1, alongside said at least one hold 6. The transport track 18 in this embodiment comprises or is formed by a conveyer belt 19. Furthermore the system 16 comprises rails 20 extending in the longitudinal direction Li of the vessell. At least one crane 21 is supported on said rails 20, such that said crane 21 can move over said at least one hold 6, for lifting sand 17 from said hold 6 and deposing of said sand 17 onto the at least one transport track 18.

[0056] In the embodiments shown said at least one transport track 18 is provided at the deck 4 of the vessel 1, and in this embodiment connects to a transfer system 22 for transferring the sand 17 from the transport track 18 to a point 23 outside the vessel 1, for discharging the sand 17 from the vessel 1 into water 24 below said point 23. In the embodiments shown in the drawings the transfer system 22 comprises an arm 25 which at least during discharging of the sand 17 extends outside a contour 26 of the deck 4 of the vessel 1, such that a distal end 27 provides for the point 23 of discharge of the sand 17, whereas the proximal end 28 connects to the at least one transport track 18. The arm 25 preferably is also provided with a conveyer belt 19 or such system for forwarding the sand 17 from the track 18 to and beyond said point 23. In the embodiments shown the arm 25 is a swiveling arm, such that it can be swiveled to a position above the deck 4 when sailing, whereas with the arm 25 the discharge point 23 can be positioned for discharging, wherein the position of discharge can even be changed during discharging.

[0057] In the embodiment of fig. 2 and 3 there are two substantially parallel transport tracks 18, and four cranes 21, each crane 21 servicing two holds 6. The two transport tracks 18 both connect to the conveyer on the arm 25. Multiple cranes 21 and transport tracks 18 can reduce time needed for discharge of the sand 17.

[0058] Fig. 4 and 5 disclose an embodiment of a vessel 1 with nine holds 6 in a single row, along a longitudinal axis L of the vessel. In this embodiment again two transport tracks 18 are provided, here shown as conveyer belts 19, wherein a set of rails 20 is provided, extending in said longitudinal direction Li, at least one rail 20 on either side of the holds 6, supporting a series of portal cranes 21, which extend over the holds 6 and transport tracks 18. In the embodiment shown, by way of example only, three such portal cranes are shown, but any suitable number can be used. Each portal crane supports at least one grabber 29 which can be lowered into one of the holds 6 for grabbing dry sand 17 from the hold and depositing this onto the transport track 18, as can be seen schematically in fig. 6 and 7A- C.

[0059] In the embodiment shown each portal crane 21 comprises one or more, for example two grabbers 29, which can be moved up and down and in a direction W perpendicular to the longitudinal axis Li, between positioned above the hold 6 and position above the transport track 18. In embodiments a chute 30 can be provided directly above the transport track, movable with the portal crane 21, for guiding sand 17, dropped by the grabber 29 onto the transport track 18. If hatches 8 are provided, they can for example be opened by sliding below the transport track and rails, as shown in fig. 6. Since the grabber 29 or grabbers 29 can be moved up and down, side ways in the direction W and longitudinally, in the direction Li, each hold 6 can be emptied easily and mechanically, as is shown in fig. 7A - C.

[0060] In the embodiments of fig. 2 - 13, there are two substantially parallel transport tracks 18, which each connect to an arm 25 as discussed, provided with transporting means 18, 19 for forwarding the sand 17 from the tracks 18 to the distal end 27 of the arm 25, for discharging the sand 17. As is shown in for example fig. 5, 9 and 12, between the transport track 18 and the respective arm 25 a cross part 18A of the transport track 18 can be provided, such that the proximal end 28, and a swivel point 26A of the arm 26 is displaced from the centerline of the vessel 1 to a position close to the respective side of the vessel 1, which can increase the reach of the arms 25 and furthermore facilitate swiveling the arms 25 to above the deck 4 more easily.

[0061] In the embodiments shown the arm or arms 25 can swivel for unloading sand 17 over a side 5 A or bow 5B of the vessel 1, by way of example. Other positions are obviously also possible for the arms 25 and tracks 18, whereas the transport tracks 18 for discharge can also continue to the discharge point 23 directly. In embodiments cranes 21 can be used to directly discharge the sand 17 overboard.

[0062] Fig. 10 and 13 show in cross section a vessel 1, and especially a hold 6 when being unloaded, wherein grabbers 29 are shown in different position during unloading sand 17. As can be seen in fig. 10 and in fig. 13 left hand side, sand 17 can be present in the hold 6 to a top level 32 above the bottom 31 of the hold 6, which top level 32 is at a height H2, significantly smaller than the maximum height Hi of the hold 6 at the level of the opening 7. The vessel 1 will in a method according to the disclosure, have been filled with a sludge 2, basically a mixture of water and sand, which is more fluid that the dry sand 17. The sludge 2 is filled into the hold 6 directly with the dredging means 10, up to approximately the level 32 of the full height Hi of the holds 6. Especially during loading sand 17 may settle to some extent, resulting in effluent 33, as for example shown in fig. 14, which can flow away, preferably through discharge openings or weirs or the like, schematically indicated in fig. 14 by reference sign 34. Thereafter during sailing over a long distance water will be drained from the sludge through a drainage system 35 provided at or near the bottom 31 of the holds, again shown schematically in fig. 14 in somewhat more detail, in order to reduce the volume of load inside the holds 6, drying the sludge to form dry sand 17, as discussed. The drainage system 35 can have drainage or inlet openings 35A near or at the bottom of 31 of the hold 6 for feeding the water into the drainage system 35. This means that water is drained from the sludge 2 and is discarded through the drainage system 35 into the water 28, preferably at a position below the waterline W of the vessel 1. Thus the concentration of solid particles in the load is increased, providing dry sand 17.

[0063] In fig. 14 three positions of the vessel are shown, during use, also referred to as position A (fig. 14 left hand side), position B (fig. 14 middle) and position C (fig. 14 right hand side).

[0064] In position A the holds 6 of the vessel 1 are fully loaded with sludge 2, having a high water content, such that the sludge 2 is hydraulically movable, for example pumpable. In fig. 14 position A the sludge 2 is shown with a layer of effluent 33 on top of it, the effluent resulting form solids settling during and directly after loading. In this position the draft D3 is largest, the load of sludge 2 in the holds 6 having the highest weight. In position A the vessel is ready for or has just started sailing from a location of dredging and loading the sludge into the holds.

[0065] In Position B the vessel has arrived at a location of discharging or unloading. Much, preferably most of the water has been removed from the sludge 2 and been expelled from the vessel by the drainage system 35. In this embodiment the hold 6 contains the remaining solid particles, forming or formed by said dry sand 17. The dry sand cannot as such be transported hydraulically and is therefore unloaded from the hold 6 using the grabbers 29 or other mechanical systems. By removing much, preferably most of the water from the sludge 2 the hold is filled only partly, by dry sand 17, such that the draft D2 is reduced relative tot the draft Di directly after loading.

[0066] In position C in fig. 14 part of the vessel 1 is shown after having unloaded or discharged substantially all of the sand 17 from the vessel 1. In position C the draft D3 is therefor even smaller than in position B.

[0067] By way of example, when being loaded (position A) the dredged sludge 2 can have a weight of between 1.1 and 1.4 times the weight of a same volume of dry sand, such as for example 1.12 - 1.16 times the weight. By way of example, in embodiments when being dredged the sludge 2 can have a weight of about 2 metric tons per cubic meter (2*103kg / m3), whereas the sand 17 resulting therefrom when being discharged can have a weight of about 1.75 metric tons per cubic meter (1.75*103kg / m3). During sailing both the volume and the weight of the cargo is therefore reduced, reducing the draft D.

[0068] In fig. 15 schematically the reduction of the draft of the vessel 1 is shown. In fig. 15 at the left hand side (comparable to position A in fig. 14) the vessel 1 is in relatively deep water, dredging sludge 2 from the water bedding B at a dredging site 100, using the dredging system 10. At the dredging location the water depth can for example be 40 meters or more, or at least can be more than a water depth at an intended discharge location 200. At or near the end of the loading process the vessel 1 will have a draft Di which is relatively large. The draft Di directly after loading can for example be 20 meters or more, such as for example 16 meters, for example between 15 and 30 meters. After raising the dredging equipment 10 appropriately, the vessel 1 will start sailing towards a discharging or unloading site 200, shown in fig. 15 at the right hand side. Due to the reduction of the volume and especially the weight of the load of the vessel 1, the draft D3 is reduced significantly, which means that the vessel 1 can sail to a discharge or unloading location 200 having a significantly smaller water depth, for example a water depth of less than 40 meters, such as less than 30 meters or even less than 20 meters. The water depth at the discharge site can for example be between 15 and 20 meters. The draft of the vessel 1 at least at the end of the sailing distance, at the discharge site 200 can be less that the relatively small water depth, for example up to 14 meters if the water depth is a minimum of 15 meters.

[0069] The vessel 1, which can for example be a refurbished bulk carrier, is designed to have a stability sufficient for it to be allowed to sail fully loaded with sludge 2. The vessel 2 can preferably be loaded to a maximum loading volume, for example loaded up to the openings of the holds 6 at the deck, without having problems with a transportable moisture limit (TML). The stability of the vessel 1 is designed such that the dredged sludge can be loaded into the vessel directly, without drying prior to loading being necessary, whereas the vessel can sail directly after loading, without having to first bring the moisture limit down to below a given TML. The vessel can preferably be loaded without having to define a TML prior to or during sailing of the loaded vessel. The vessel can have a loading capacity of over 50.000 (fifty thousand) cubic meters, preferably over 100.000 (one hundred thousand) cubic meters, and / or can have a loading capacity of over 100.000 (one hundred thousand) metric tons, for example over 200.000 (two hundred thousand) metric tons.

[0070] With a vessel 1 according to the disclosure and in a method according to the disclosure water emanating from the sludge 2 is dispensed of from the vessel during sailing. In order to prevent pollution and especially in order to prevent for example species, which may be loaded with the sludge, from being disposed into water distant from the dredging site, to which said species may be considered invasive (for example non-indigenous), the vessel can comprise filter system 36 for filtering the water drained form the sludge 2 before being disposed of. The filter system 36 can for example be the same filtering system 36 used for filtering water disposed of from ballast tanks 37 of the vessel 1. The filtering system 36 can for example comprise a filter 38 in the drainage system 35, which filter system 36 may be as is as known in the art of ballast water systems and ballast water tanks. A pump 39 can be provided for forcing the water through the filter system 36 into a ballast tank 37 or out into the surrounding water.

[0071] Fig. 16 discloses an embodiment of part of a dredging system 10, comprising a dredging pipe or assembly of pipes 11, and a dredging head 12 connected thereto. A recycle line 11A can be provided along the pipe or pipes 11 for feeding effluent from a or the hold 6 to the dredging head 12, for improving dredging efficiency and / or limiting pollution. The pipe or at least an upper one of the pipes 11 is connected to the vessel through a rotating or pivoting or otherwise flexible coupling 11B, such that the position of the pipe or pipes 11 can be adjusted, for example to the depth of the water whereas the pipe or pipes 11 are connected to the crane or cranes 15 by cables 15A, such that the system 10 can be hoisted to a lifted position along side or aboard of the vessel 1, and a working position, as shown in fig. 16, with the head 12 close to or resting on the bedding B.

[0072] A vessel 1 for use in a method according to the disclosure preferably has a hull 3 which has an outer shell 3A and an inner shell 3B, and a ballast water treatment equipment 40, comprising the ballast water tank 37, filter 38 and preferably a pump 39, in a known manner. As described, the water discharge system 35 is connected to or forms part of said ballast water treatment equipment 40 or vice versa.

[0073] In preferred embodiments a vessel 1 according to the disclosure, when loaded to the maximum loading capacity with dredged sludge and removing substantially all effluent water from the vessel accumulated over a period of 24 hours, has a draft of over 15 meters, and when loaded with dry sand which is obtained by subsequently draining process water from the sludge and discharging said process water from the vessel, has a draft of less than 15 meters, preferably less than 14,5 meters, such as for example a draft of between 13 and 15 meters, more preferably between 13,5 and 14,5 meters.

[0074] For transport vessels, dredgers and barges and the like cargo vessels 1 it is important to ascertain a volume of cargo stored in any cargo hold 6, such as dredging product, such as for example sand. In a method according to the disclosure such volume can be easily and accurately be assessed using a volumetric measuring system 50 as for example shown in and explained referring to fig. 17 - 19.

[0075] In a method of the disclosure for measuring product volume 51 in a cargo hold 6, first data concerning an internal volume of an empty hold 6 is obtained and stored in a computer system 53. For example the cargo hold is scanned when empty using a scanning system 52, especially a 3D scanning system 52, such as for example a laser scanning system. Thus data concerning the shape and volume of the empty hold 6 is assessed and stored in a computer system 53. Alternatively the data may be obtained differently, for example by measurement or from drawings or the like data files. Then product 54, especially bulk product such as dredging product, sand or granular product or the like, is loaded into the hold 6, filling the hold 6 to an extent.

[0076] The product 54 loaded into the hold 6 will have a top surface 55 which will mostly not be flat, especially if the product is a bulk product such as for example sand or such relatively dry, granular product. The top surface 55 can for example be formed by one or more bumps, can be irregularly accidented or the like, and / or can be generally cone shaped or multiple-cone shaped, as shown in fig. 17. At least one scan is made of the top surface 55, using the scanning system 52, such that data concerning the surface configuration can be entered into the computer system 53, as well as of its position in the hold 6. As shown in fig. 19 a plot 56 can be made of said data concerning the profile and position of the top surface 55.

[0077] After obtaining the relevant data concerning the volume of the hold 6 and the profile of the surface 55, a computer algorithm is then used in said computer system 53 for combining the data concerning the volume of the hold 6 and the data concerning the profile and position of the surface 55 of the product 54, such that the actual volume can be computed of the product 54.

[0078] By using a 3D scanning system 52 for obtaining data concerning the product surface 55 and the hold 6 point clouds capturing the shape and sizes of the surface 55 and the hold 6 are obtained which can be easily combined to accurately assess the volume of the product 54 loaded into the hold, without for example the need to level out said product and thus preventing people from having to enter the hold 6 for that purpose during or after loading.

[0079] Such method can be described as a method for assessing a volume of bulk cargo in a cargo hold, wherein in a computer system data is entered concerning volume of said cargo hold, especially size and shape of said cargo hold, when empty, said data also referred to as first data; and data is entered concerning a profile and position of a surface of product loaded in said cargo hold, said data also referred to as second data, in the computer system the first data and second data are combined for calculating the volume of the cargo in the cargo hold. F or said calculation the computer system comprises an algorithm, which can in embodiments be designed for calculating said volume based on cloud points or such representation of said first and / or second data. The data can be obtained by said 3D scanning, wherein the first data can be obtained prior to and / or after obtaining said second data, and wherein in embodiments the first data can be stored in the computer system for later reference, for example when calculating a volume of different bulk cargo in the same cargo hold at a later time.

[0080] Fig. 18 shows an example of an arrangement of a scanning system 52 at a hold 6, which scanning system 52 can be permanently installed or, preferably, can be at least partly mobile, such that it can for example be used for different holds 6 and can be stored securely and safely after use. The scanning system 52 comprises at least one 3D laser scanner 57, which can for example be mounted on an arm 58, such that it can be supported in a position above and / or in the hold 6. The scanner 57 is or can be connected to the computer system 53, for transferring scanning data to the computer system 53, for example by wire or wireless.

[0081] In embodiments the scanner 57 can be designed for obtaining all relevant data from a single position. Alternatively the scanner 57 can be repositioned during scanning. As is shown in fig. 18 schematically, the scanner 57 can be repositioned during scanning progress, as for example schematically shown in striped lines in fig. 18, bringing the scanner 57 for example to four different sides of the hold 6. In such embodiments preferably markers 59 are provided at the hold 6, preferably in fixed positions, such that a reference is obtained for the combination of the data obtained in the different positions. Such markers can also be used for combining data obtained of the hold when empty with the data obtained of the surface 55. It will be understood that any suitable scanner or combination of scanners can be used for obtaining the relevant data, such as for example but not limited to hand held scanners, fixed scanners, drone supported scanners or the like.

[0082] A volumetric measuring system 52 and method can be used for any hold and bulk load provided therein, wherein hold shapes and sizes can be measured prior to or after loading the cargo into or unloading the cargo from the hold, or in between, for example for assessing part of a cargo removed, from the hold, whereas hold shapes and sizes could also be preloaded into a computer system of the system, for example for standard holds or repeat measurements.

[0083] The invention is by no means limited to the embodiments shown in the drawings, which are shown by way of example only. Many variations thereof are possible within the claims.

[0084] For example a vessel 1 can have a different number of holds, which may be designed differently. The water drained from the sludge may be discarded differently, for example by draining the water and forcing it upward and overboard. Dry sand may be discharged differently, for example by using cranes for directly unloading the sand overboard, or a combination of cranes and transport tracks or the like. Different dredging equipment may be used, or dredging equipment in different positions.

Claims

Claims1. Method for delivering sand to a work site, wherein sludge comprising sand and water is dredged at a dredging site and the sludge is loaded directly into a transport vessel, where after the transport vessel sails to a delivery site, wherein the vessel is a vessel having a high loading capacity, the sludge being loaded into the vessel while the sludge has a high moisture content, wherein during sailing of the vessel to the delivery site process water is discharged from the vessel, reducing the moisture content of the sludge for obtaining dry sand, and limiting the draft of the vessel, where after at the delivery site the sand is discharged from the vessel in dry condition.

2. Method according to claim 1, wherein the sludge is dredged hydraulically, preferably using suction dredging equipment.

3. Method according to claim 1 or 2, wherein the sludge is dredged using dredging equipment provided aboard the transport vessel.

4. Method according to any one of claims 1 - 3, wherein the vessel is loaded to maximum loading capacity in volume of the vessel.

5. Method according to any one of the preceding claims, wherein the vessel is loaded with sludge in a pumpable state, wherein the vessel has a stability sufficient for it to be loaded with said sludge to maximal loading capacity in volume, without having to define a TML prior to or during sailing of the loaded vessel.

6. Method according to any one of the preceding claims, wherein the sand is discharged from the vessel directly into a work site forming the discharge site.

7. Method according to any one of the preceding claims, wherein a vessel is used having a loading capacity of:over 50.000 cubic meters, preferably at least 100.000 cubic meters; and / or over 100.000 metric ton, preferably at least 200.000 metric ton.

8. Method according to any one of the preceding claims, wherein the sand is discharged having a moisture content such that the sand is suitable for mechanical discharge.

9. Method according to any one of the preceding claims, wherein the sand is discharged from the vessel using a dry sand discharge system provided on the vessel, wherein the sand is preferably discharged over a board, bow or side of the vessel.

10. Method according to any one of the preceding claims, wherein the sand is discharged at a discharge location having a water depth of less than 40 meters, preferably less than 30 meters, such as for example less than 20 meters, such as between 15 and 20 meters.

11. Method according to any one of the preceding claims, wherein during discharging of said process water from the vessel the process water is filtered for retrieving invasive species such as animals and plants from the water.

12. Method according to any one of the preceding claims, wherein as a vessel a converted ore carrier is used.

13. Method according to any one of the preceding claims, wherein: the sludge is loaded into a hold of the vessel, wherein the process water is drained from the sludge and is discharged from the vessel through one or more discharge openings fed through one or more inlets at or near a lower side of the hold; or the sludge is loaded into a series of holds of the vessel, wherein the process water is drained from the sludge and is discharged from the vessel through one or more discharge openings fed through one or more inlets at or near a lower side of each hold.

14. Method according to any one of the preceding claims, wherein the vessel sails to the discharge location with any hold of the vessel containing sludge open at an upper side.

15. Transport vessel comprising at least one hold for holding sludge, the sludge comprising sand, wherein the vessel has a loading capacity of: over 50.000 cubic meters of sludge, preferably at least 75.000 cubic meters, more preferably at least 100.000 cubic meters; or over 100.000 metric tons of sludge, preferably at least 150.000 metric tons, more preferably at least 200.000 metric tons of sludge, wherein the vessel has at least one water discharge system for discharging process water drained from the sludge.

16. Transport vessel according to claim 15, wherein the vessel is provided with dredging equipment, preferably dredging equipment for dredging and hydraulically loading dredged sludge into the vessel.

17. Transport vessel according to claim 15 or 16, wherein the transport vessel has a loading volume and wherein the vessel has a stability sufficient to sail when fully loaded in volume with a pumpable sludge, without having to determine a TML of the sludge prior to sailing after loading.

18. Transport vessel according to any one of claims 15 - 17, wherein the transport vessel comprises a discharge system for discharge of dry sand from the at least one hold of the vessel.

19. Transport vessel according to claim 18, the discharge system comprises at least one transport track extending in a longitudinal direction of the vessel alongside said at least one hold, and rails extending in the longitudinal direction of the vessel, wherein at least one crane is supported on said rails, such that said crane can move over said at least one hold, for lifting sand from said hold and deposing of said sand onto the at least one transport track.

20. Transport vessel according to claim 19, wherein said at least one transport track is provided at a deck of said vessel, and can connect to a transfer system for transferring the sand from the transport track to a point outside the vessel, for discharging the sand from the vessel into water below said point.

21. Transport vessel according to any one of claims 15 - 20, wherein the vessel has a hull which has at least an inner shell and an outer shell and ballast tanks, wherein ballast water treatment equipment is provided for treatment, of ballast water prior to discharge of said ballast water from the vessel, wherein the water discharge system is connected to or comprises said ballast water treatment equipment, for treatment of process water prior to being discharged from the vessel.

22. Transport vessel according to any one of claims 15 - 21, wherein the vessel: when loaded to the maximum loading capacity with dredged sludge and removing substantially all effluent water from the vessel accumulated over a period of 24 hours, has a draft of over 15 meters, and when loaded with dry sand which is obtained by subsequently draining process water from the sludge and discharging said process water from the vessel, has a draft of less than 15 meters, preferably less than 14,5 meters, such as for example a draft of between 13 and 15 meters, more preferably between 13,5 and 14,5 meters.

23. Transport vessel according to any one of claims 15 - 21, wherein the vessel comprises a volumetric measuring system for measuring a volume of a load in a cargo hold, said volumetric measuring system comprising at least one 3D scanner and a computer system, wherein a logarithm is provided for calculating said volume of said load in said cargo hold by combining data concerning size and shape said hold when empty and scanning data concerning a surface configuration and position of said surface of the load in said hold.

24. Method for assessing a volume of bulk cargo in a cargo hold, wherein in a computer system: data is entered concerning volume of said cargo hold, especially size and shape of said cargo hold, when empty, said data also referred to as first data; and data is entered concerning a profile and position of a surface of product loaded in said cargo hold, said data also referred to as second data; wherein in the computer system the first data and second data are combined for calculating the volume of the cargo in the cargo hold.

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