NL2004484C2

NL2004484C2 - Submersible dredging device, assembly of a riser system and submersible dredging device, vessel and method of driving a slurry pump.

Info

Publication number: NL2004484C2
Application number: NL2004484A
Authority: NL
Inventors: Cornelis Hendrik Berg; Verichev Stanislav; Hendrik Anton Albers; Robert Gerard Ketterij
Original assignee: Ihc Holland Ie Bv
Priority date: 2010-03-31
Filing date: 2010-03-31
Publication date: 2011-10-04
Also published as: WO2011122942A1

Description

SUBMERSIBLE DREDGING DEVICE, ASSEMBLY OF A RISER SYSTEM AND SUBMERSIBLE DREDGING DEVICE, VESSEL AND METHOD OF DRIVING A SLURRY PUMP

5 The invention relates to a submersible dredging device, an assembly of a submersible dredging device and a riser system, a vessel having a riser system with a submersible dredging device and a method of driving a slurry pump.

Submersible dredging devices may be used for delivering slurry from 10 a waterbed of a water volume (for instance the sea) to a water surface (for instance the sea surface). The submersible dredging device may be arranged to deliver subsea slurry from a seabed via a riser system to the sea surface.

Subsea slurries can be delivered to the sea surface using submersible is centrifugal dredge pumps installed over a vertical deep sea riser system. These pumps are normally driven by electric or by hydraulic motors. Energy for the motors is supplied using electric and hydraulic umbilicals, respectively. Power is generated at the vessel by combustion engines, converted into electric (or hydraulic) power, which is then transferred 20 subsea to the pump drive converting electric (or hydraulic) into the motion.

Submersible dredging devices, such as submersible dredge pumps, are supposed to provide high slurry production rates and therefore can have a power of up to 2 MW or even more. Combined with the necessity to install such pumps at large depths (for instance in the order of several 25 kilometers), this assumes that high power motors must be employed to drive these pumps. Electric or hydraulic motors can be used.

In case of electric motors, power is usually supplied using one or more electric umbilicals. A disadvantage of this approach is the need to seal the electric motors and the associated electric control system and/or to 2 provide for an ambient pressure compensation system. Furthermore, the umbilicals may become complex and/or expensive as both the needed power and the depth increase. Possible failure of the electric system in this case may also be an issue.

5 In the case of hydraulic motors, there could be two approaches: oil hydraulics and water hydraulics. According to the first approach, there is provided a submersible hydraulic system powered from the vessel using electric umbilicals. A disadvantage of this approach is the increased number of systems so that the reliability of the system may be 10 compromised as the number of system components that could fail is increased. Also, any system has efficiency less that 100%, which means that a larger number of systems generally results in a smaller overall efficiency.

Alternatively, according to a second approach, water hydraulics 15 systems are used. According to this approach, positive-displacement type hydraulic motors are to be used since most of the other types of hydraulic motors do not deliver sufficiently high powers and torques. Normally, such motors deliver either sufficiently high power but small rpm (in this case, a gear system is to be installed in between of pump and motor), or 20 sufficiently high rpm but small power (in this case, a number of motors driving the same pump is to be installed in a series). Furthermore, hydraulic fluid is normally not allowed to contain solids (particles) with sizes (diameter) larger than 100 microns. Also, solids content in a power fluid should be kept sufficiently small.

25 In subsea slurry production roughly 50% of water is produced. This water can be separated at the vessel from the useful solid material and the separated waste water can be reinjected back into the water volume.

3

Consequently, if one supposes to use this waste water as a drive fluid, then a considerably complex filtering and separation system needs to be installed.

It is an object of the present invention to provide an improved drive 5 assembly for driving a pump.

It is a further object of the invention to provide a submersible dredging device wherein the disadvantages of the prior approaches have been reduced or even completely removed.

It is a further object of the present invention to provide an improved 10 method of driving a pump, for instance a slurry pump in a submersible dredging device.

It is a further object of the invention to provide a submersible dredging device having an improved subsea power generation and transfer.

According to a first aspect of the invention at least one of the objects 15 is achieved in a submersible dredging device for pumping slurry through a riser system, the dredging device comprising: - a slurry pump for pumping slurry through the riser system, the slurry pump comprising a pump inlet and a pump outlet, the pump inlet and pump outlet being configured to be connected to a dredging pipe of the 20 riser system; and - a drive assembly for driving the pump, wherein the drive assembly comprises a reinjection channel connecting a drive assembly inlet and a drive assembly outlet, the drive assembly outlet and drive assembly inlet being configured to be connected to a water reinjection pipe of the riser 25 system for discharging water into the water volume, the drive assembly further comprising a drive impeller arranged in the reinjection channel and coupled to drive the pump.

The pump could be any type of pump, for instance a piston type pump or a cntrifiigal pump. In embodiments of the present invention the 4 pump is a slurry pump comprising a slurry pump impeller for transporting slurry from the slurry pump inlet to the slurry pump outlet and wherein the drive impeller of the drive assembly is coupled to the slurry pump impeller so as to drive the slurry pump impeller.

5 In an embodiment the reinjected water is discharged near the water bed. In a further embodiment the reinjected water is discharged into the water bed, for instance into the sea bed. In another embodiment the reinjection water is used to release slurry from the sea bottom. In an embodiment a drive impeller is present in the reinjection channel, the drive 10 impeller forming a drive, for instance a generator, for the slurry pump. The flow of water through the reinjection channel is used as a power source. This reduces, and in specific embodiment avoids, the use of separate umbilicals for electrical or hydraulic supply of energy. According to this embodiment, it is assumed that reinjection water is used as power fluid to 15 drive the submersible dredging device.

In an embodiment reinjection water or waste water containing relatively large particles and relatively high solids content can be used to power the system.

In an embodiment the slurry channel is part of the dredging pipe of 20 the riser system for delivering slurry upwards from the waterbed to the water surface, while the reinjection channel is part of reinjection pipe for transporting a flow (of water) from the surface downwards towards (near) the waterbed.

In an embodiment the slurry pump comprises a slurry pump 25 impeller. The submersible dredging device comprises at least two impellers, at least one in an upward channel and at least one in downward channel. The at least two impellers can be present in separated casings in a single house, or in an embodiment in separated (generally connected) housings.

5

In an embodiment the drive impeller and slurry pump impeller have several blades. In embodiments the drive impeller is arranged to be driven by the stream of water inside the reinjection pipe of the riser system and the slurry pump impeller is arranged to generate a stream of slurry in the 5 dredging pipe of the riser system. Depending on the application, impellers can have different embodiments: open and closed type, radial, axial, helical, or radial-axial type (e.g. like Francis turbine) etc., different sizes (for instance diameters) and/or different shapes.

In an embodiment the drive impeller is mechanically coupled with 10 the slurry pump impeller. This allows the use of a submersible dredging device that is purely mechanical and does not need electrical power and/or additional hydraulical power to function. The power can be generated at the vessel using the submersible dredging device to which it is coupled via the riser system.

is In an embodiment the drive impeller and slurry pump impeller are positioned coaxially. Both impellers may be arranged in one or more housings by using suitable bearings. The bearings can be aligned. The coaxial position allows a simple coupling between the driving impeller (drive impeller) and the driven impeller (slurry pump impeller).

20 In an embodiment rotating parts are made of wear-resistant material.

In an embodiment rotating parts can have wear resistant coatings or can be composed of several parts with different materials.

In an embodiment a drive shaft couples the drive impeller and slurry pump impeller. The drive impeller is driven by the waste water, which 25 results in rotational motion of the second impeller transmitted via the common shaft. The number of systems and energy conversions is reduced here as much as possible.

In an embodiment the drive shaft comprises two rigidly coupled shafts having a rotary seal in between. An advantage of this embodiment is 6 that one of the devices (i.e. slurry pump or drive assembly) may be replaced without needing to lift the other one.

In an embodiment a transmission, for instance a gear transmission or a similar transmission, couples the drive impeller and slurry pump 5 impeller. This allows different rotational speeds of the impellers as well as possibility to install both devices not coaxially but, for instance, at the same angle.

In an embodiment the water reinjection pipe of the riser system has a water reinjection outlet directed at the waterbed. In an embodiment the 10 outlet may comprise a nozzle allowing water from the reinjection pipe to be discharged at high speed into the volume of water. In this way slurry from the waterbed can be released before it is sucked into the slurry channel.

According to an aspect of the invention an assembly of a riser system is and a submersible dredging device is provided. The submersible dredging device can have any of the features of the submersible dredging device described in this application. In an embodiment the assembly further comprises a water pump connected to the reinjection channel via the riser system. The water pump is arranged to provide a flow of (reinjection) 20 water through the riser system towards the submersible dredging device. The impeller in the reinjection channel will rotate as a result of the water flow. This allows to provide a system wherein the pump is positioned at a distance from the submersible device, said pump forming the original generator for pumping the slurry. Further this allows providing the 25 submersible dredging device without electrical or additional hydraulic inputs.

In embodiments of the present invention the assembly comprises a first housing for accommodating the at least the drive impeller of the drive assembly and a second housing for accommodating at least the slurry 7 pump impeller, wherein at least one of said housing is connected to the riser system. The connection between the housing and the riser system may be a substantially rigid connection (for instance, screwed, via rigid pipes). In another embodiment the connection is a flexible connection (for 5 instance, flexible hoses). In the latter case, the housing may be dynamically decoupled from the riser system. It could also be top-tensioned to the vessel or a buoyancy module or just attached to the buoyancy module.

The assembly may further comprise a reinjection pump configured 10 and arranged to receive a liquid fraction of the slurry pumped up by the slurry pump and to direct the liquid fraction through the reinjection channel. The liquid fraction may be liquid (for instance water) originating from the mixture of liquid and solid (i.e. the slurry) and being arrived at the vessel via the riser system. In many practical situations the reinjection 15 pump is arranged at or in the vessel, the pump may be positioned elsewhere as long as it is possible the transport the liquid fraction downward through the reinjection pipe with a view to discharge the liquid anywhere in the water volume.

According to another aspect of the invention a drive assembly is 20 provided for driving a pump, for pumping a mixture through a first pipeline, the pump comprising a pump impeller, a pump inlet and a pump outlet which inlet and outlet are connectable or connected to the pipe line, wherein the drive assembly comprises: - a channel connecting a drive assembly inlet and a drive assembly 25 outlet, the drive assembly outlet and drive assembly inlet being configured to be connected to a second pipeline through which a liquid may be caused to flow; - a drive impeller arranged in the channel so as to be driven by the liquid flow; 8 wherein the drive impeller is coupled to drive the pump impeller of the pump.

The pump may or may not be of a submersible type. For instance, the pipelines may be (at least partly) land-based. The pump may be a 5 slurry pump to transport slurry to a discharge location, for instance on board a vessel or land-based location. The pipelines may be arranged to transport any type of medium, for instance oil, water, slurry, etc. In a specific embodiment the first pipeline transports a mixture of liquid and solids (for instance slurry from the bottom of a volume of water) in a first 10 direction, while the second pipeline transports another liquid or the liquid part of this earlier-mentioned mixture in a second direction, opposite the first direction, to return the liquid to a specific location. The liquid flow in the second pipeline may then be used to energize the pump in the first pipeline. The first and second pipelines may be part of an upright riser 15 system, but may also be part of different systems, for instance systems for transporting slurry in a more horizontal direction.

In embodiments of the invention connection means are provided to mechanically couple the drive impeller with the slurry pump impeller. The the connection means may be configured to cause rotation of the pump 20 impeller by the rotation of the drive impeller. The connections means may comprise a transmission gear to transmit the rotation of the drive impeller to rotation of the pump impeller according to a specific transmission ratio.

According to an aspect of embodiments of the invention a vessel (for instance a ship, pontoon or the like) is provided having a (vertical sub sea) 25 riser system with a submersible dredging device described herein. In an embodiment the vessel comprises a water pump connected to the reinjection channel via the riser system. This embodiment allows a reduced number and/or complexity of umbilicals.

9

In an embodiment the vessel has a separator for separating water from the slurry received via the riser system. The separator can separate the water from the delivered slurry and in an embodiment a water outlet of the separator is connected with the reinjection channel. The water taken from 5 the waterbed may be discharged again in the volume of water, for instance near the water bed.

In an embodiment preprocessed sea water only or a combination of waste water and preprocessed sea water is used in the riser system to drive the impeller and to form a drive for the slurry pump as well.

10 According to a further aspect a riser system for dredging is provided having a dredging pipe and a discharge channel (for instance - but not limited to- a reinjection pipe), wherein the discharge channel comprises a discharge impeller forming a drive for a pump arranged in the dredging pipe of the riser system.

15 In an embodiment the riser system and/or the submersible dredging device comprises multiple pumps wherein a subset of the pumps is driven by waste water, while other pumps are driven by sea water, for instance pre-processed sea water following ecological restrictions.

According to a further aspect a method of driving a slurry pump in a 20 submersed dredging device coupled via a riser system to a vessel is provided. The method comprises providing a water flow from the vessel to the submersed dredging device and driving the slurry pump by means of the water flow. The method involves a "water mill" like principle wherein the dredging pump is operated by the mechanical forces generated by a 25 stream of water driving flowing past an impeller of a driving assembly.

According to an embodiment the method may comprise separating water from the slurry received through the riser system and pumping the separated water back into the riser system so as to generate the water flow driving the slurry pump.

10

Although the invention is described in connection with several embodiments thereof, it will be clear that the invention is not limited to the embodiments shown. The skilled person will recognize this disclosure encompasses all explicit and implicit combinations of features indicated in 5 this application.

Further features, advantages and details of the present invention will also become apparent from the following description of embodiments thereof, wherein reference is made to the accompanying figures.

Fig. 1 shows a ship having a vertical sub sea riser system and a 10 submersible dredging device according to an embodiment of the present invention;

Fig. 1A shows a detail of the embodiment of the submersible dredging device according to figure 1; and

Fig. 2 shows a schematic cross sectional view of an embodiment of the 15 submersible dredging device.

FIG 1 provides a schematic view of a dredging vessel having a vertical riser system having a power fluid channel and a dredging device at the lower end. The dredging vessel (v) is provided with a riser system 20 comprising a dredging pipe 1, a discharge pipe 2 and means to connect 20 both pipes to the vessel. The dredging pipe 1 has a suction end 3 at which slurry (s) can be sucked into the pipe. In the embodiment shown in figure 1 the slurry is dredged using a submersible remote-controlled vehicle 6 that is provided with dredging equipment for removing slurry from the sea bed. In other embodiments of the invention other types of dredging methods 25 and/or dredging equipment may be used.

The dredging pipe 1 has a discharge end 4 at which the pumped slurry may be discharged in the vessel's hold 9. The slurry may be pumped upward by one or more dredge pumps 5, for instance -but not limited to-one or more centrifugal pumps. The dredge pump 5 may be arranged at 11 any position along the dredging pipe 1, but usually is arranged close to or at the suction end 3 of the pipe. The discharge pipe 2 is connected to a water pump 7. The water pump 7 can generate a downward water flow along the discharge pipe 2 towards a nozzle 8. The water discharged from 5 the nozzle 8 may be discharged at a depth within the boundaries provided for by international maritime regulations.

The water pumped by the water pump into the discharge pipe may be water that has been separated from the slurry that has been pumped up by the dredge pump 9. The water is herein also referred to as "waste water" or lo "reinjection water". The latter term may be used since this water is sucked up by the dredging pipe and once it has arrived at the sea surface and has been separated by a separator in the vessel, is pumped into in the discharge pipe, also called the reinjection pipe, and reinjected into the sea close to the suction end of the dredging pipe.

15 The vessel (v) further comprises an active control system 11 (schematically shown) for controlling the flow rate of the waste fluid. If there is not enough waste water produced at the vessel, the missing volumes are to be sucked from the sea. On the contrary, if the flow rate of waste water is higher than required, the waste water is to be discharged 20 using a relief valve (not shown in the figures) installed in the discharge pipe.

Figures 1A and 2 schematically show a view and a cross section of a submersible dredging device 12 in accordance with an embodiment of the invention. In the shown embodiment the device 12 comprises a water 25 driven submerged centrifugal slurry pump. It can be used to deliver slurry from a sea bed to the sea surface if connected to a vertical sub sea riser system.

Referring to figure 2, the dredging device 12 is shown in more detail. The dredging device 12 comprises a housing 13 divided in a first 12 compartment 14 for accommodating the dredge pump 5 and a second compartment 15 accommodating a drive assembly for driving the dredge pump, as will be explained hereafter. The compartments or casings are separated by a partition wall 36. The housing 13 comprises a dredge pump 5 inlet 15 and dredge pump outlet 16, both openings being in fluid communication with the first compartment 14. Similarly, the housing comprises an inlet 17 and an outlet 18, both openings being in fluid communication with the second compartment 15.

A lower part 19 and an upper part 20 of the dredging pipe 1 are to connected to the inlet 15 and outlet 16 of the first compartment, respectively. Similarly, an upper part 21 and a lower part 22 of the pipe 2 are connected to the inlet 17 and outlet 18 of the second compartment 15, respectively.

Rotatably attached to the housing and arranged inside the first 15 compartment 14 thereof is a slurry pump impeller 25 of the slurry pump 5, while in the second compartment 15a drive impeller 26 is arranged. The drive impeller 26, more specifically, in the present embodiment, the vanes or blades 38 thereof, is arranged to be rotatable in the direction denoted by arrow 28 around axis 29. The slurry pump impeller is connected with the 20 drive impeller by a common shaft 28 (or two coupled shafts with a gear box in between (not shown in the drawings), and rotatable in the same direction as the drive impeller.

Depending on the application, drive impeller 26 and slurry pump impeller 25 are placed either in separate casings (pump housings) or at one 25 casing with separated chambers or compartments 14,15. More specifically, slurry pump impeller 25 is present in a slurry channel (not shown) formed between slurry inlet 15 and outlet 16, while the drive impeller is present in a similar channel extending between inlet 17 and outlet 18 of compartment 15. In the partition wall 36 a shaft sealing 37 is provided to allow shaft 28 13 to be rotated without slurry from compartment 14 entering compartment 15 or vice versa. Also, depending on the application, drive impellers can be different: open and closed type radial, axial, and helical, or of the turbine type etc.

5 As mentioned above, the water pump pumps water into the upper part 21 of the reinjection pipe 2. The pressurized water flow then enters the second compartment 15 and causes the reinjection or drive impeller 26 to rotate. After the water flow has provided motion for the reinjection or drive impeller 26 of the dredging device 12, it leaves the compartment 15 to and enters the lower part 22 of the reinjection pipe 2, Finally the water is discharged by nozzle 8 and directed to the seabed (s).

In the embodiment shown in figure 2 the impellers 25 and 26 are positioned coaxially and are coupled directly via mechanical means. More specifically, rotational motion of the drive impeller 26 is transmitted into 15 rotational motion of the slurry pump impeller 25 via the rigid shaft 28. Alternatively, the shaft may be embodied as two (or more) rigidly coupled shafts having a rotary seal in between. In another embodiment a gear transmission is provided between both impellers so that the rotational movement of the drive impeller may be transmitted in a suitable 20 transmission ratio to the slurry pump impeller. The rotation of the impeller 25, more specifically vanes or blades 27 thereof, causes the slurry present in the dredging pipe 1 to be pumped towards the vessel.

The driving force exerted by the drive impeller 26 on the dredging pump impeller 25 of the dredging pump 5 is sufficient to cause the 25 dredging pump to transport the slurry upward towards the dredging vessel (v). There is no need anymore for a separate drive mechanism, such as an electric or one or more separate hydraulic motors. The entire system may be purely mechanical with rigid couplings and all the power is generated at the vessel. At the same time, waste water containing relatively large 14 particles and relatively high solids content can be used to power the system. There is no requirement to loop power fluid so the waste water after passing the drive impeller may be continuously discharged into the sea bottom at high flow rates.

5 In some embodiments only one pump, for instance one slurry pump, is used. In other embodiments more than one pump is used. They can be distributed along the riser system at certain mutual distances and/or large booster stations may be located somewhere along the riser system. The waste water (which is to be used as (a part of) the motive fluid) is 10 discharged at any location, for instance as deep as possible. The channels in which the individual reinjection impellers driving the respective pumps are positioned, could each be connected to a separate supply line or could be fed from one main supply line (with certain pressure), for instance via a system of valves.

is Operating parameters of the three devices, i.e. a first pump (e.g. slurry pump) for pumping a medium through the first pipeline, a second pump (e.g. reinjection pump) for pumping a medium through the second pipeline and the driving assembly for driving the second pump are to be chosen in such way that best efficiency points of their efficiency curves either match 20 each other or belong to more or less the same range of flowrates, which guarantees optimal energy consumption and dynamic stability if the flowrates (both slurry production rate and, consequently, flowrate of the drive fluid) are varied within the range required by the operational conditions.

25 While preferred embodiments of this invention have been shown and described, modifications thereof can be made by one skilled in the art without departing from the spirit or teaching of this invention. The embodiments described herein are exemplary only and are not limiting. Many variations and modifications of the system and apparatus are 15 possible and are within the scope of the invention. Accordingly, the scope of protection is not limited to the embodiments described herein, but is essentially limited by the claims, the scope of which shall include all equivalents of the subject matter of the claims.

5

Claims

1. Onderwaterbaggerinrichting voor het baggeren van slurry vanaf een waterbodem van een waterpartij, zoals slurry van een zeebodem, via een stijgsysteem naar een 5 wateroppervlak, de baggerinrichting omvattende: een slurrypomp voor het pompen van slurry door het stijgsysteem, waarbij de slurrypomp een pompinlaat en een pompuitlaat omvat, waarbij de pompinlaat en pompuitlaat uitgevoerd zijn om verbonden te worden met een baggerpijp van het stijgsysteem; en 10. een aandrijfsamenstel voor het aandrijven van de pomp, waarin het aandrijfsamenstel een herinjectiekanaal omvat dat een aandrijfsamenstelin-laat en een aandrijfsamensteluitlaat verbindt, waarbij de aandrijfsamenstel-uitlaat en aandrijfsamenstelinlaat uitgevoerd zijn om verbonden te worden met een waterherinjectiepijp van het stijgsysteem voor het afVoeren van 15 water naar de waterpartij, waarbij het aandrijfsamenstel verder een aandrijfrotor omvat die gerangschikt is in het herinjectiekanaal en die gekoppeld is om de pomp aan te drijven.1. Underwater dredging device for dredging slurry from a water bottom of a water body, such as slurry from a seabed, via a rising system to a water surface, the dredging device comprising: a slurry pump for pumping slurry through the rising system, wherein the slurry pump has a pump inlet and comprises a pump outlet, wherein the pump inlet and pump outlet are designed to be connected to a dredging pipe of the riser system; and 10. a drive assembly for driving the pump, wherein the drive assembly comprises a reinjection channel connecting a drive assembly inlet and a drive assembly outlet, the drive assembly outlet and drive assembly inlet configured to be connected to a water re-injection pipe of the riser riser system of water to the water body, wherein the drive assembly further comprises a drive rotor arranged in the reinjection channel and coupled to drive the pump.

2. Baggerinrichting volgens conclusie 1, waarin de pomp een slurrypomp met een 20 slurrypomprotor voor het transporteren van slurry vanaf de slurrypompinlaat naar de slurrypompuitlaat is en waarin de aandrijfrotor van het aandrijfsamenstel gekoppeld is aan de slurrypomprotor teneinde de slurrypomprotor aan te drijven.2. Dredging device according to claim 1, wherein the pump is a slurry pump with a slurry pump promoter for transporting slurry from the slurry pump inlet to the slurry pump outlet and wherein the drive rotor of the drive assembly is coupled to the slurry pump promoter to drive the slurry pump promoter.

3. Onderwaterbaggerinrichting volgens conclusie 2, waarin de aandrijfrotor mecha- 25 nisch gekoppeld is aan de slurrypomprotor.3. Underwater dredging device according to claim 2, wherein the drive rotor is mechanically coupled to the slurry pump rotor.

4. Onderwaterbaggerinrichting volgens conclusie 2 of 3, waarin de aandrijfrotor en slurrypomprotor coaxiaal gerangschikt zijn.An underwater dredging device according to claim 2 or 3, wherein the drive rotor and slurry pump rotor are arranged coaxially.

5. Onderwaterbaggerinrichting volgens een van de conclusies 2-4, waarin een gemeenschappelijke aandrijfas de aandrijfrotor en slurrypomprotor koppelt om rotatiebeweging van de aandrijfrotor over te brengen op de slurrypomprotor.The underwater dredging device of any one of claims 2-4, wherein a common drive shaft couples the drive rotor and slurry pump rotor to transfer rotational movement of the drive rotor to the slurry pump rotor.

6. Onderwaterbaggerinrichting volgens conclusie 5, waarin de aandrijfas twee starre gekoppelde assen met daartussen een roteerafdichting omvat.An underwater dredging device according to claim 5, wherein the drive shaft comprises two rigid coupled shafts with a rotary seal between them.

7. Onderwaterbaggerinrichting volgens een van de voorafgaande conclusies, omvat- 5 tende een overbrengingsmechanisme tussen de aandrijfrotor en slurrypomprotor omvat.7. Underwater dredging device as claimed in any of the foregoing claims, comprising a transfer mechanism between the drive rotor and slurry pump rotor.

8. Onderwaterbaggerinrichting volgens een van de voorafgaande conclusies, waarin de aandrijfrotor en slurrypomprotor verscheidene bladen omvatten. 10An underwater dredging device according to any one of the preceding claims, wherein the drive rotor and slurry pump promoter comprise several blades. 10

9. Onderwaterbaggerinrichting volgens een van de voorafgaande conclusies, omvattende een eerste huis voor het huisvesten van de ten minste ene aandrijfrotor van het aandrijfsamenstel en een tweede huis voor het huisvesten van ten minste de slurrypomprotor. 159. Underwater dredging device as claimed in any of the foregoing claims, comprising a first housing for housing the at least one drive rotor of the drive assembly and a second housing for housing at least the slurry pump promoter. 15

10. Onderwaterbaggerinrichting volgens een van de conclusies 1-8, omvattende een gecombineerd huis voor de ten minste ene slurrypomprotor en aandrijfrotor.10. Underwater dredging device as claimed in any of the claims 1-8, comprising a combined housing for the at least one slurry pump rotor and drive rotor.

11. Onderwaterbaggerinrichting volgens een van de conclusies 2-10, waarin de aan- 20 drijfrotor en pomprotor verschillende vormen en/of afmetingen hebben.11. Underwater dredging device as claimed in any of the claims 2-10, wherein the drive rotor and pump rotor have different shapes and / or dimensions.

12. Samenstel van een stijgsysteem en een onderwaterbaggerinrichting volgens een van de voorafgaande conclusies, waarin het samenstel verder een waterpomp omvat die verbonden is met de herinjectiepijp van het stijgsysteem. 25An assembly of a riser system and an underwater dredging device according to any one of the preceding claims, wherein the assembly further comprises a water pump connected to the re-injection pipe of the riser system. 25

13. Samenstel volgens conclusie 12, omvattende een eerste huis voor het huisvesten van de ten minste ene aandrijfrotor van het aandrijfsamenstel en een tweede huis voor het huisvesten van ten minste de slurrypomprotor, waarin ten minste een van de genoemde huizen verbonden is met het stijgsysteem en waarin de verbinding 30 een starre verbinding of een flexibele verbinding is.13. Assembly as claimed in claim 12, comprising a first housing for housing the at least one drive rotor of the drive assembly and a second housing for housing at least the slurry pump promoter, wherein at least one of said housing is connected to the riser system and wherein the connection 30 is a rigid connection or a flexible connection.

14. Samenstel volgens conclusie 13, waarin de waterherinjectiepijp een waterher-injectieuitlaat heeft die gerangschikt is om naar de waterbodem gericht te worden.An assembly according to claim 13, wherein the water re-injection pipe has a water re-injection outlet arranged to be directed to the water bottom.

15. Samenstel volgens een van de voorafgaande conclusies, omvattende een herinjec-tiepomp die uitgevoerd en gerangschikt is om een vloeistoffractie van de slurry die door de slurrypomp opgepompt is te ontvangen en om de vloeistoffractie door 5 het herinjectiekanaal te sturen.15. An assembly according to any one of the preceding claims, comprising a reinjection pump that is designed and arranged to receive a liquid fraction from the slurry pumped up by the slurry pump and to direct the liquid fraction through the reinjection channel.

16. Aandrijfsamenstel voor het aandrijven van een pomp, bijvoorbeeld een slurrypomp, voor het pompen van een mengsel door een eerste pijpleiding, waarbij de pomp een pomprotor, een pompinlaat en een pompuitlaat omvat, welke inlaat en 10 uitlaat verbonden of te verbinden zijn met de pijpleiding, waarin het aandrijfsa menstel omvat: - een kanaal, bijvoorbeeld een herinjectiekanaal, dat een aandrijfsamen-stelinlaat en een aandrijfsamensteluitlaat verbindt, waarbij de aandrijfsa-mensteluitlaat en de aandrijfsamenstelinlaat uitgevoerd zijn om verbonden 15 te worden met een tweede pijpleiding, bijvoorbeeld een waterherinjectiepijp van een stijgsysteem, via welke een vloeistof, bijvoorbeeld herinjectie-vloeistof, kan stromen; een aandrijfrotor die gerangschikt is in het kanaal teneinde aangedreven te worden door de vloeistofstroom; 20. waarin de aandrijfrotor gekoppeld is om de pomprotor van de pomp aan te drijven.16. Drive assembly for driving a pump, for example a slurry pump, for pumping a mixture through a first pipeline, the pump comprising a pump rotor, a pump inlet and a pump outlet, which inlet and outlet are connected or connectable to the pipeline, wherein the drive assembly comprises: - a channel, for example a reinjection channel, connecting a drive assembly inlet and a drive assembly outlet, the drive assembly outlet and the drive assembly inlet being arranged to be connected to a second pipeline, for example a water re-injection pipe of a riser system through which a liquid, for example, reinjection liquid, can flow; a drive rotor arranged in the channel to be driven by the fluid stream; 20. wherein the drive rotor is coupled to drive the pump's rotor.

17. Aandrijfsamenstel volgens conclusie 16, omvattende verbindingsmiddelen om op mechanische wijze de aandrijfrotor te koppelen met de slurrypomprotor, waarin 25 de verbindingsmiddelen uitgevoerd zijn om de pomprotor door de rotatie van de aandrijfrotor te roteren.17. Drive assembly according to claim 16, comprising connecting means for mechanically coupling the drive rotor to the slurry pump rotor, wherein the connecting means are adapted to rotate the pump rotor through the rotation of the drive rotor.

18. Aandrijfsamenstel volgens conclusie 16 of 17, verder gekenmerkt door de maatregel van het aandrijfsamenstel volgens een van de conclusies 1-15. 3018. Drive assembly according to claim 16 or 17, further characterized by the measure of the drive assembly according to one of claims 1-15. 30

19. Aandrijfsamenstel volgens een van de conclusies 16-18 in combinatie met de eerste en tweede pijpleiding.Drive assembly according to any of claims 16-18 in combination with the first and second pipeline.

20. Vaartuig met een stijgsysteem met een onderwaterbaggerinrichting volgens een van de conclusies 1-14, waarin een herinjectiewaterpomp op het vaartuig verbonden is met het herinjectiekanaal via de herinjectiepijp van het stijgsysteem.A vessel with a riser system with an underwater dredging device according to any of claims 1-14, wherein a reinjection water pump on the vessel is connected to the reinjection channel via the reinjection pipe of the riser system.

21. Voertuig volgens conclusie 20, omvattende een scheider voor het scheiden van water van de slurry die ontvangen is via het stijgsysteem.The vehicle of claim 20, comprising a separator for separating water from the slurry received via the riser system.

22. Vaartuig volgens conclusie 21, waarin een wateruitlaat van de scheider verbonden is met het herinjectiekanaal. 10The vessel of claim 21, wherein a water outlet of the separator is connected to the reinjection channel. 10

23. Stijgsysteem voor het baggeren van slurry vanaf een waterbodem naar een wateroppervlak, het systeem omvattende een baggerpijp voor het opwaarts transporteren van slurry in de richting van het wateroppervlak en een afvoerpijp, bij voorkeur een herinjectiepijp, voor het transporteren van water in neerwaartse richting 15 naar de waterbodem, waarbij het systeem verder omvat een afvoerrotor die ge rangschikt is in de afvoerpijp voor het aandrijven van een slurrypomp in de baggerpijp.23. Rise system for dredging slurry from a water bottom to a water surface, the system comprising a dredging pipe for transporting slurry upwards towards the water surface and a drain pipe, preferably a reinjection pipe, for transporting water downwards. to the water bottom, the system further comprising a discharge rotor arranged in the discharge pipe for driving a slurry pump in the dredging pipe.

24. Werkwijze voor het aandrijven van een slurrypomp in een onderwater- 20 baggerinrichting die via een stijgsysteem gekoppeld is aan een vaartuig door het verschaffen van een waterstroom vanaf het vaartuig in de richting van de onderwaterbaggerinrichting en door het aandrijven van de slurrypomp door middel van de waterstroom.24. Method for driving a slurry pump in an underwater dredging device which is coupled to a vessel via a rising system by providing a water flow from the vessel in the direction of the underwater dredging device and by driving the slurry pump by means of the water flow.

25. Werkwijze volgens conclusie 24, omvattende het scheiden van water van de slurry die ontvangen wordt via het stijgsysteem en voor het terugpompen van het gescheiden water in het stijgsysteem teneinde de waterstroming die de slurrypomp aandrijft, te genereren.The method of claim 24, comprising separating water from the slurry received through the riser system and pumping back the separated water into the riser system to generate the water flow that drives the slurry pump.

26. Werkwijze volgens conclusie 24 of 25, waarin een baggerinrichting volgens een van de conclusies 12-16 toegepast wordt.A method according to claim 24 or 25, wherein a dredging device according to any of claims 12-16 is used.

27. Gebruik van een baggerinrichting, vaartuig en/of aandrijfsamenstel volgens een van de voorafgaande conclusies.Use of a dredging device, vessel and / or drive assembly according to one of the preceding claims.