Device, apparatus, system and method for sediment plume suppression

Abstract

A device (10) for use in the suppression of a sediment plume (P), comprises an inlet arrangement (12) for receiving therethrough a fluid flow (F) and an outlet arrangement (14) for directing said fluid flow (F) out from the device (10). The outlet arrangement (14) is configured to redirect at least a portion of the fluid flow (F) received through the inlet arrangement (12) in a lateral direction, thereby forming a fluid barrier inhibiting the formation and / or movement of the sediment plume (P).

Description

[0001] DEVICE, APPARATUS, SYSTEM AND METHOD FOR SEDIMENT PLUME SUPPRESSION

[0002] FIELD

[0003] This relates to a device for use in the suppression of a sediment plume; to an underwater apparatus’, e.g. underwater excavation apparatus’, comprising said device; to a system comprising said device and said underwater apparatus; and to associated methods of sediment plume suppression.

[0004] BACKGROUND

[0005] Subsea systems, such as pipeline systems, conduits, cables and the like, form a critical part of the World’s industrial infrastructure. In order to protect subsea infrastructure, e.g. from the harsh marine environment and / or from damage from passing marine vessels, subsea excavation equipment is used to form a trench system in the seabed into which the pipeline systems, conduits, cables and the like may be laid and which is then covered over.

[0006] In the energy industry, for example, excavation of the seabed is used extensively in order to lay the pipelines, conduits and / or cables required to support offshore installations, including offshore oil and / or gas installations and more recently the offshore renewable energy infrastructure seen as critical in the move towards low carbon energy production.

[0007] All methods of subsea seabed excavation liberate solid particles from the seabed surface which are lifted into suspension in the water column and create diffuse sediment plumes. Large particles within the plume, such as gravel and heavy sands, fall relatively close to the excavation site. Smaller particles have the potential to travel much further, particularly where there are significant currents. The higher the plume is lifted into the water column, the further it may travel from the excavation site.

[0008] Although sediment plumes occur naturally, for example at the mouth of rivers or with the interaction of waves and tides on the seabed, from an environmental impact perspective it is generally considered desirable to minimise the spread of sediment plumes caused by excavation beyond the area of excavation in order to limit any adverse ecological impact. This is particularly the case in locations where there may be pre-existing contamination of the seabed from industrial or other pollutants. In non-polluted areas, sediment plumes can still be environmentally damaging due to seabed fauna or flora being buried.

[0009] SUMMARY

[0010] Aspects of the present disclosure relate to a device for use in the suppression of a sediment plume; to an underwater apparatus’, e.g. underwater excavation apparatus’, comprising said device; to a system comprising said device and said underwater apparatus; and to associated methods of sediment plume suppression.

[0011] According to a first aspect, there is provided a device for use in the suppression of a sediment plume, the device comprising: an inlet arrangement for receiving therethrough a fluid flow; and an outlet arrangement comprising one or more outlets for directing said fluid flow out from the device, wherein the device is configured to redirect at least a portion of the fluid flow received through the inlet arrangement so as to form a fluid barrier inhibiting the formation and / or movement of the sediment plume.

[0012] In use, the device is located above an underwater worksite to be excavated and / or other area of seabed subject to disturbance from mechanical and / or jetting means with the outlet arrangement oriented towards the seabed. The device may be configured and / or operable to receive, via the inlet arrangement, the fluid flow which is then directed out of the device via the outlet arrangement. The device may be configured to redirect at least a portion of the fluid flow so as to form a fluid barrier inhibiting the formation and / or movement of the sediment plume. The fluid flow exiting the device may take the form of a jet of water above the plume generation area that presents a barrier to the upward movement of the suspended solids forming the sediment plume.

[0013] Beneficially, the device suppresses the formation and / or movement of the sediment plume, amongst other things obviating and / or mitigating adverse ecological impacts that may otherwise occur from the spread of the sediment plume. For example, by suppressing the sediment plume the device may limit the spread of industrial or other pollutants contained in the seabed. Moreover, by suppressing the sediment plume the device may reduce the impact of underwater excavation processes on seabed fauna and / or flora in the area surrounding the worksite, e.g. by preventing and / or mitigating the disturbance of their habitat and / or by preventing the seabed fauna and / or flora from being buried. As described above, the device is configured to redirect at least a portion of the fluid flow received through the inlet arrangement so as to form a fluid barrier inhibiting the formation and / or movement of the sediment plume.

[0014] The device may be configured to redirect the fluid flow in a lateral or substantially lateral direction, i.e. to one or more sides of the device.

[0015] Alternatively or additionally, the device may be configured to redirect the fluid flow in a forward or substantially forward direction.

[0016] Alternatively or additionally, the device may be configured to redirect the fluid flow in a rearward or substantially rearward direction.

[0017] As described above, the device comprises an outlet arrangement.

[0018] The outlet arrangement may be configured to redirect at least a portion of the fluid flow received through the inlet arrangement so as to form a fluid barrier inhibiting the formation and / or movement of the sediment plume.

[0019] The outlet arrangement may comprise a single outlet.

[0020] The outlet may be annular or substantially annular.

[0021] Beneficially, the provision of an annular or substantially annular outlet arrangement facilitates the formation of a continuous or substantially continuous fluid barrier over the worksite.

[0022] Alternatively, the outlet may be part-annular, e.g. defining a segment of a circle.

[0023] The provision of a part-annular outlet may be beneficial where it is desired to prevent the formation and / or movement of a plume in a particular direction only.

[0024] The device may comprise a plurality of different, interchangeable, outlet arrangements. The outlet arrangement may comprise a plurality of outlets.

[0025] Where the outlet arrangement comprises a plurality of outlets, the outlets may be circumferentially arranged and / or spaced, e.g. equally spaced.

[0026] At least one of the one or more outlets of the outlet arrangement may be oriented radially, e.g. solely radially.

[0027] At least one of the one or more outlets of the outlet arrangement may be oriented horizontally or substantially horizontally.

[0028] Beneficially, this facilitates the formation of a radial fluid barrier which prevents the upwards movement of the sediment plume.

[0029] Alternatively or additionally, at least one of the one or more outlets of the outlet arrangement may be angled with respect to the horizontal so as to direct the fluid flow axially (e.g. upwards or downwards) in addition to said lateral direction, forward direction and / or rearward direction.

[0030] At least one of the one or more outlets of the outlet arrangement may be angled with respect to the horizontal, i.e. a non-zero angle relative to horizontal. The outlet arrangement may be angled such that, in use, the fluid flow is directed towards and / or around the worksite.

[0031] Beneficially, the provision of an angled outlet arrangement facilitates the formation of a conical fluid barrier which prevents the upwards and lateral movement of the sediment plume.

[0032] At least one of the one or more outlets of the outlet arrangement may comprise or take the form of a nozzle.

[0033] Beneficially, the fluid flow exiting the device may comprise or take the form of a fluid jet. As described above, the device comprises an inlet arrangement for receiving therethrough the fluid flow to be directed towards and / or around the worksite.

[0034] The inlet arrangement may comprise one or more inlets.

[0035] In particular embodiments, the inlet arrangement may comprise a single inlet.

[0036] The device may be oriented so that the inlet arrangement, e.g. at least one inlet of the inlet arrangement, is oriented vertically or substantially vertically.

[0037] Alternatively or additionally, the device may be oriented so that the inlet arrangement, e.g. at least one inlet of the inlet arrangement, is disposed at an angle, i.e. a non-zero angle with respect to the vertical.

[0038] Beneficially, the orientation of the inlet arrangement may be selected to reduce energy losses which may otherwise occur where the fluid flow is forced to change direction between the inlet arrangement and the outlet arrangement. Alternatively or additionally, the orientation of the one or more of the inlets may be selected to reduce the overall height of the device and / or associated underwater apparatus, permitting use of the device in shallow water applications.

[0039] As described above, the device is configured to redirect at least a portion of the fluid flow received through the inlet arrangement so as to form a fluid barrier inhibiting the formation and / or movement of the sediment plume.

[0040] The device, e.g. outlet arrangement, may be configured to direct all of the fluid flow in a lateral direction.

[0041] Alternatively, the device, e.g. at least one of the one or more outlets of the outlet arrangement, may be configured and / or operable to direct a portion, e.g. a remaining portion, of the fluid flow in an axial direction, e.g. vertically or substantially vertically towards the worksite. The device, e.g. outlet arrangement, may define an excavation outlet. The at least one outlet configured and / or operable to direct a portion, e.g. a remaining portion, of the fluid flow in an axial direction may comprise or take the form of a central or substantially central outlet of the device.

[0042] The device may comprise a rotor.

[0043] The device may comprise a stator.

[0044] As an alternative to or in addition to the outlet arrangement being configured to redirect the fluid flow so as to form the fluid barrier, the stator may be configured to redirect the fluid flow so as to form the fluid barrier.

[0045] The device may comprise a rotary drive arrangement.

[0046] The rotary drive arrangement may comprise a rotary drive.

[0047] The rotary drive may comprise or take the form of a motor.

[0048] The rotary drive may comprise or take the form of an electric rotary drive, e.g. an electric motor.

[0049] Alternatively or additionally, the rotary drive may comprise or take the form of a fluid-powered rotary drive, e.g. a hydraulic motor or pneumatic motor.

[0050] The device may comprise a housing.

[0051] The inlet arrangement may be integrally formed with the housing. Alternatively, the inlet arrangement may be coupled to the housing.

[0052] The outlet arrangement may be integrally formed with the housing. Alternatively, the outlet arrangement may be coupled to the housing.

[0053] The device may comprise or may be coupled to a power conduit. The power conduit may be configured and / or operable to supply power to the device, e.g. to the rotary drive arrangement.

[0054] Where the rotary drive comprises or takes the form of an electric rotary drive, the power conduit may comprise or take the form of an electric cable.

[0055] Where the rotary drive comprises or take the form of a fluid-powered rotary drive, the power conduit may comprise or take the form of a hydraulic or pneumatic hose or hoses.

[0056] The device may comprise or may be coupled to a conveyance.

[0057] The conveyance may be configured and / or operable to facilitate handling of the device. By controlling the conveyance, the position of the device relative to the worksite may be controlled.

[0058] The power conduit may form the conveyance. Alternatively, the power conduit and conveyance may comprise separate members. The conveyance may carry the power conduit.

[0059] The conveyance may comprise or take the form of a conduit, cable or the like.

[0060] The device may be coupled to a surface facility, e.g. a surface vessel such as a dredging vessel or the like, via the conveyance.

[0061] According to a second aspect, there is provided an underwater apparatus comprising the device of the first aspect.

[0062] In particular embodiments, the underwater apparatus may comprise or take the form of an underwater, e.g. subsea, excavation apparatus.

[0063] The underwater, e.g. subsea, excavation apparatus may comprise or take the form of a mass flow excavation apparatus. The underwater, e.g. subsea, excavation apparatus may comprise or take the form of a controlled flow excavation apparatus. The apparatus may, for example, be configured and / or operable to produce a fluid flow at a pressure of typically around 35 kPa to 120 kPa and volume flow of typically around 1 m3 / s to 8 m3 / s. In contrast to mass flow excavation apparatus’, the higher pressure capability of the controlled flow excavation apparatus may mean that the apparatus is suitable for operation in both excavation (e.g., jetting) mode and also in a suction mode where the apparatus may be used for collection and transportation of seabed material away from the worksite W.

[0064] The apparatus may for example comprise the underwater excavation apparatus shown and described in WO2019 / 202298 or PCT / GB2023 / 050095, both Rotech Group Limited, the contents of which are incorporated herein in their entirety by way of reference.

[0065] Alternatively or additionally, the underwater apparatus may comprise or take the form of: a dredging apparatus; an underwater, e.g. subsea, mining apparatus; an underwater, e.g. subsea, drilling apparatus; and / or an underwater, e.g. subsea, pile-driving apparatus.

[0066] The device may form part of the underwater apparatus. For example, the device may be integrally formed with the underwater apparatus. Alternatively, the device may be coupled to, e.g. form an attachment to, the underwater apparatus.

[0067] The apparatus may comprise an inlet arrangement for receiving therethrough a fluid flow.

[0068] The apparatus may comprise an outlet arrangement comprising one or more outlets for directing said fluid flow out from the apparatus.

[0069] At least one of the one or more outlets of the outlet arrangement may be configured and / or operable to direct the fluid flow in an axial direction, e.g. vertically or substantially vertically towards the worksite. The outlet configured and / or operable to direct the fluid flow in an axial direction may comprise or take the form of a central or substantially central outlet of the apparatus.

[0070] The apparatus may comprise a rotor.

[0071] The apparatus may comprise a stator.

[0072] The apparatus may comprise a rotary drive arrangement.

[0073] The rotary drive arrangement may comprise or take the form of a motor.

[0074] The rotary drive arrangement may comprise or take the form of an electric rotary drive, e.g. an electric motor.

[0075] Alternatively or additionally, the rotary drive arrangement may comprise or take the form of a fluid-powered rotary drive, e.g. a hydraulic motor or pneumatic motor.

[0076] The apparatus may comprise a housing.

[0077] The inlet arrangement may be integrally formed with the housing. Alternatively, the inlet arrangement may be coupled to the housing.

[0078] The outlet arrangement may be integrally formed with the housing. Alternatively, the outlet arrangement may be coupled to the housing.

[0079] The device may, for example, be coupled to the underwater apparatus so that the device is offset from the underwater apparatus.

[0080] For example, the apparatus may be configured so the device is disposed behind the fluid flow, e.g. excavation jet, created by the apparatus.

[0081] Alternatively, the apparatus may be configured so the device is disposed ahead of the fluid flow, e.g. excavation jet, created by the apparatus.

[0082] The apparatus may further comprise a coupling arrangement. The coupling arrangement may comprise or take the form of a mounting frame.

[0083] However, it will be understood that the coupling arrangement may take other forms.

[0084] At least one of the housing of the apparatus and the housing of the device may be removable coupled to the coupling arrangement, this for example permitting removal for repair, replacement and / or interchange of the apparatus and / or the device.

[0085] Beneficially, this may reduce inventory, which may be particularly beneficial for offshore installations or vessels where access to the installation or vessel may be limited and / or involve significant costs.

[0086] The apparatus may comprise or may be coupled to a power conduit.

[0087] The power conduit may be configured and / or operable to supply power to the apparatus, e.g. to the rotary drive arrangement and / or the rotary drive arrangement of the device.

[0088] Where the rotary drive comprises or take the form of an electric rotary drive, the power conduit may comprise or take the form of an electric cable.

[0089] Where the rotary drive comprises or take the form of a fluid-powered rotary drive, the power conduit may comprise or take the form of a hydraulic or pneumatic hose or hoses.

[0090] The apparatus may comprise or may be coupled to a conveyance.

[0091] The conveyance may be configured and / or operable to facilitate handling of the apparatus. By controlling the conveyance, the position of the apparatus relative to the worksite may be controlled. The power conduit may form the conveyance. Alternatively, the power conduit and conveyance may comprise separate members. The conveyance may carry the power conduit.

[0092] The conveyance may comprise or take the form of a conduit, cable or the like.

[0093] The apparatus may be coupled to a surface facility, e.g. a surface vessel such as a dredging vessel or the like, via the conveyance.

[0094] According to a third aspect, there is provided an underwater system comprising: the apparatus’ of the first aspect; and the device of the first aspect.

[0095] The system may comprise or take the form of an underwater excavation system.

[0096] The system may comprise a vessel V, e.g. a dredging vessel.

[0097] The system may comprise a suction tube. The suction tube may be configured and / or operable to suck seabed material.

[0098] The system may comprise a suction head. The suction head may comprise or may be coupled to a distal end of the suction tube.

[0099] In particular embodiments, the suction head may comprise or take the form of a passive drag cutter. However, it will be understood that the suction head may take other forms, such as a system of high-pressure jets, or a rotating mechanical cutter. The suction head may be configured and / or operable to break up the seabed material allowing it to be sucked into the suction tube.

[0100] According to a third aspect, there is provided a method for suppression of a sediment plume using the device of the first aspect, the apparatus of the second aspect and / or the system of the third aspect. According to the method, the device is located above an underwater worksite to be excavated and / or other area of seabed subject to disturbance from mechanical and / or jetting means with the outlet arrangement oriented towards the seabed. The device may be configured and / or operable to receive, via the inlet arrangement, the fluid flow which is then directed out of the device via the outlet arrangement. The device may be configured to redirect at least a portion of the fluid flow so as to form a fluid barrier inhibiting the formation and / or movement of the sediment plume. The fluid flow exiting the device may take the form of a jet of water above the plume generation area that presents a barrier to the upward movement of the suspended solids forming the sediment plume.

[0101] The invention is defined by the appended claims. However, for the purposes of the present disclosure it will be understood that any of the features defined above or described below may be utilised in isolation or in combination. For example, features described above in relation to one of the above aspects or below in relation to the detailed description below may be utilised in any other aspect, or together form a new aspect.

[0102] BRIEF DESCRIPTION OF THE DRAWINGS

[0103] These and other aspects will now be described, by way of example only, with reference to the accompanying drawings, in which:

[0104] Figure 1 shows a diagrammatic view of a device for use in the suppression of a sediment plume;

[0105] Figure 2 shows a diagrammatic view of an apparatus for use in the suppression of a sediment plume, comprising the device shown in Figure 1 ;

[0106] Figure 3 shows a diagrammatic view of a system for use in the suppression of a sediment plume, comprising the apparatus shown in Figure 2;

[0107] Figure 4 shows a diagrammatic view of an alternative apparatus for use in the suppression of a sediment plume, comprising the device shown in Figure 1;

[0108] Figure 5 shows a diagrammatic view of a system for use in the suppression of a sediment plume, comprising the apparatus shown in Figure 4;

[0109] Figure 6 shows a diagrammatic view of an alternative apparatus for use in the suppression of a sediment plume;

[0110] Figure 7 shows a diagrammatic view of a system for use in the suppression of a sediment plume, comprising the apparatus shown in Figure 6;

[0111] Figure 8 shows a diagrammatic view of an alternative device for use in the suppression of a sediment plume;

[0112] Figure 9 shows a diagrammatic view of a system for use in the suppression of a sediment plume, comprising the apparatus shown in Figure 8;

[0113] Figure 10 shows a diagrammatic view of an alternative device for use in the suppression of a sediment plume;

[0114] Figure 11 shows a diagrammatic view of a system for use in the suppression of a sediment plume, comprising the apparatus shown in Figure 10; and

[0115] Figure 12 shows a diagrammatic view of an alternative system for use in the suppression of a sediment plume.

[0116] DETAILED DESCRIPTION OF THE DRAWINGS

[0117] Referring first to Figures 1 to 3 of the accompanying drawings, there are shown diagrammatic views of a device, generally denoted 10, for use in the suppression of a sediment plume P, an underwater apparatus, generally denoted 100, comprising the device 10, and an underwater system, generally denoted 1000, comprising the apparatus 100.

[0118] As shown in Figure 1 , the device 10 comprises an inlet arrangement, generally denoted 12, and an outlet arrangement, generally denoted 14.

[0119] In use, and as will be described further below, the device 10 is located above an underwater worksite W to be excavated with the outlet arrangement 14 oriented towards the seabed S. The device 10 is configured and / or operable to receive, via the inlet arrangement 12, a fluid flow F which is then directed out of the device 10 via the outlet arrangement 14. In the illustrated system 1000, the fluid flow F is formed by the device 10 drawing in water surrounding the device 10. The outlet arrangement 14 is configured to redirect at least a portion of the fluid flow F so as to form a fluid barrier inhibiting the formation and / or movement of the sediment plume P. The device may be configured to redirect the fluid flow in a lateral or substantially lateral direction, i.e. to one or more sides of the device; in a forward or substantially forward direction; and / or in a rearward or substantially rearward direction. In the illustrated device 10, the fluid flow F exiting the device 10 takes the form of a jet of water above the plume generation area that presents a barrier to the upward movement of the suspended solids forming the sediment plume P.

[0120] Beneficially, the device 10 suppresses the formation and / or movement of the sediment plume P, amongst other things obviating and / or mitigating adverse ecological impacts that may otherwise occur from the spread of the sediment plume P. For example, by suppressing the sediment plume P the device 10 may limit the spread of industrial or other pollutants contained in the seabed S. Moreover, by suppressing the sediment plume P the device 10 may reduce the impact of underwater excavation processes on seabed fauna and / or flora (not shown) in the area surrounding the worksite W, e.g. by preventing and / or mitigating the disturbance of their habitat and / or by preventing the seabed fauna and / or flora from being buried by the material of the plume P. As described above, the device 10 is configured to redirect at least a portion of the fluid flow F received through the inlet arrangement 12 so as to form a fluid barrier inhibiting the formation and / or movement of the sediment plume P. The illustrated device 10 is configured to redirect all of the fluid flow F to form the fluid barrier.

[0121] In the illustrated device 10, the outlet arrangement 14 is annular and comprises a single annular or substantially annular outlet 16.

[0122] Beneficially, the provision of an annular outlet arrangement 14 facilitates the formation of a continuous or substantially continuous curtain of water exiting the device 10 so as to form the fluid barrier over the worksite W.

[0123] In the illustrated device 10, the outlet 16 takes the form of a nozzle.

[0124] Beneficially, providing the outlet 16 in the form of a nozzle facilitates the formation of a fluid jet - said fluid jet forming the fluid flow F - sufficient to suppress the sediment plume P.

[0125] In the illustrated device 10, the outlet 16 is oriented at an angle a with respect to a central longitudinal axis A of the device 10 so as to direct the fluid flow F towards and / or around the worksite W in use.

[0126] Beneficially, the provision of an angled outlet arrangement 14 facilitates the formation of a conical fluid barrier which prevents or inhibits the upwards and lateral movement of the sediment plume P, thereby facilitating the suppression of the plume P.

[0127] As described above, the device 10 comprises an inlet arrangement 12 for receiving therethrough the fluid flow F to be directed towards and / or around the worksite W.

[0128] In the illustrated device 10, the inlet arrangement 12 comprises a single inlet 18. As shown in Figure 1 , the inlet arrangement 12 is oriented at an angle to longitudinal axis A. In order to draw the fluid flow F into the inlet arrangement 12 and then direct it through the device 10 to the outlet arrangement 14, the device 10 comprises a rotor, generally denoted 20, comprising impellor blades 22 disposed around a hub 24. As shown in Figure 1 , the hub 24 comprises a conical portion 26 which diverges the fluid flow F as it enters the rotor 20.

[0129] The rotor 20 is driven by a rotary drive arrangement 28. In the illustrated device 10, the rotary drive arrangement 28 takes the form of an electric motor. However, it will be understood that the rotary drive arrangement 28 may take other forms such as a fluid- powered rotary drive in the form of a hydraulic motor, pneumatic motor or the like.

[0130] The device 10 further comprises a stator, generally denoted 30. The stator 30 is configured and / or operable to direct the fluid flow F exiting the rotor 20 to the outlet arrangement 14.

[0131] As shown, the stator 30 comprises static blades 32 extending from a hub 34. As shown in Figure 1 , the hub 34 comprises conical portion 36 which converges the fluid flow F towards the outlet arrangement 14.

[0132] In use, the rotary drive arrangement 28 is operable to drive rotation of the rotor 20. The stator 30 directs the fluid flow F exiting the rotor 20 towards the outlet arrangement 14.

[0133] As shown in Figure 1 , the device 10 further comprises a housing 38. In the illustrated device 10, the inlet arrangement 12 and outlet arrangement 14 are integrally formed with the housing 38. However, it will be understood that the housing 38 and at least one of the inlet arrangement 12 and the outlet arrangement 14 may take the form of separate components.

[0134] As noted above, Figure 2 of the accompanying drawings shows a diagrammatic view of the underwater apparatus 100 comprising the device 10 for suppressing a sediment plume P.

[0135] The illustrated underwater apparatus 100 takes the form of an underwater excavation apparatus. The illustrated apparatus 100 takes the form of a controlled flow excavation apparatus. The apparatus 100 is configured and / or operable to produce a fluid flow at a pressure of typically around 35 kPa to 120 kPa and volume flow of typically around 1 m3 / s to 8 m3 / s. In contrast to mass flow excavation apparatus’, the higher pressure capability of the controlled flow excavation apparatus 100 means that the apparatus 100 is suitable for operation in both excavation (e.g., jetting) mode and also in a suction mode where the apparatus 100 may be used for collection and transportation of seabed material away from the worksite W.

[0136] However, it will be understood that the apparatus 100 may alternatively comprise or take the form of a mass flow excavation apparatus, a trailing suction hopper dredger, a cutter suction dredger, or other form of underwater apparatus.

[0137] As shown in Figure 2, the apparatus 100 comprises an inlet arrangement, generally denoted 102, and an outlet arrangement, generally denoted 104.

[0138] In the illustrated apparatus 100, the outlet arrangement 104 is axial i.e. co-linear with longitudinal axis B and comprises a single outlet 106 in the form of a nozzle.

[0139] In the illustrated apparatus 100, the inlet arrangement 102 comprises a single inlet 108. As shown in Figure 2, the inlet arrangement 102 is oriented at an angle to longitudinal axis B.

[0140] The apparatus 100 comprises a rotor, generally denoted 110, comprising impellor blades 112 disposed around a hub 114. As shown in Figure 2, the hub 114 comprises a conical portion 116 which diverges the fluid flow F as it enters the rotor 110.

[0141] The rotor 110 is driven by a rotary drive arrangement 118. In the illustrated apparatus 100, the rotary drive arrangement 118 takes the form of an electric motor. However, it will be understood that the rotary drive arrangement 118 may take other forms such as a fluid-powered rotary drive in the form of a hydraulic motor, pneumatic motor or the like. The apparatus 100 further comprises a stator, generally denoted 120. The stator 120 is configured and / or operable to direct the fluid flow exiting the rotor 110 to the outlet arrangement 104.

[0142] As shown, the stator 120 comprises static blades 122 extending from a hub 124. As shown in Figure 2, the hub 124 comprises conical portion 126 which converges the fluid flow towards the outlet arrangement 104.

[0143] As shown in Figure 2, the apparatus 100 further comprises a housing 128. In the illustrated apparatus 100, the inlet arrangement 102 and outlet arrangement 104 are integrally formed with the housing 128. However, it will be understood that the housing 128 and at least one of the inlet arrangement 102 and the outlet arrangement 104 may take the form of separate components.

[0144] As also shown in Figure 2, the apparatus 100 further comprises a coupling arrangement, generally denoted 130. In the illustrated apparatus 100, the coupling arrangement 130 comprises or takes the form of a mounting frame 132 into which the housings 38, 128 are mounted. However, it will be understood that the coupling arrangement 130 may take other forms. For example, the housing 128 may be directly coupled to the housing 38 or the housings 38, 128 may be integrally formed.

[0145] In the illustrated apparatus 100, the housings 38, 128 may be removable coupled to the coupling arrangement 130, this for example permitting removal for repair, replacement and / or interchange of the apparatus 100 and / or the device 10. Beneficially, this may reduce inventory, which may be particularly beneficial for offshore installations or vessels where access to the installation or vessel may be limited and / or involve significant costs.

[0146] Referring now in particular to Figure 3 of the accompanying drawings, which shows the system 1000 in use, the apparatus 100 is located above an underwater worksite W to be excavated. The rotary drive arrangement 118 is operable to drive rotation of the rotor 110 so as to draw water surrounding the apparatus 100 into the inlet arrangement 102. The stator 120 is configured and / or operable to direct the fluid flow exiting the rotor 110 to the outlet arrangement 104. The fluid exiting the apparatus 100 forms an excavation jet J directed towards the worksite W so as to excavate trench T. As shown in Figure 3, in order to suppress the sediment plume P resulting from excavation of the trench T, the rotary drive arrangement 28 of the device 10 is configured and / or operable to drive rotation of the rotor 20 so as to draw water surrounding the device 10 into the inlet arrangement 12. The stator 30 is configured and / or operable to direct the fluid flow exiting the rotor 20 to the outlet arrangement 14. The fluid flow F exiting the device 10 forms a fluid barrier over the worksite W which inhibits the formation and / or movement of the sediment plume P.

[0147] As also shown in Figure 3, the apparatus 100 comprises a power conduit 134. The power conduit 134 is configured and / or operable to supply power to the apparatus 100, e.g. to the rotary drive arrangements 28, 118. In the illustrated apparatus 100, the power conduit 134 also forms a conveyance configured and / or operable to facilitate handling of the apparatus 100 from a surface facility V. As shown in Figure 3, the surface facility V takes the form of a vessel such as a tug or support vessel. Beneficially, the apparatus 100 can be utilised with relatively small vessels such as tugs or support vessels, which tend to be more readily available and are cheaper to operate than e.g. dredging vessels which are typically very large. However, it will be understood that the device 10 and / or apparatus 100 may be utilised with any suitable vessel or facility, including dredging vessels.

[0148] As shown in Figure 3, in the illustrated apparatus 100 the device 10 is disposed behind the excavation jet J and the device 10 is vertically or substantially vertically oriented so as to produce a conical fluid barrier over the worksite W, and thereby suppress the sediment plume P.

[0149] It will be understood that various modifications may be made without departing from the scope of the claimed invention.

[0150] For example, Figures 4 and 5 of the accompanying drawings show diagrammatic views of an alternative apparatus, generally denoted 200, for use in the suppression of a sediment plume P, and an underwater system, generally denoted 2000, comprising the apparatus 200.

[0151] As shown in Figures 4 and 5, the apparatus 200 is similar to the apparatus 100 described above and comprises the device 10. However, in the illustrated apparatus 200 the device 10 is disposed ahead of the excavation jet J and the device 10 is angled (i.e. longitudinal axis A of device 10 is arranged at a non-zero angle relative to vertical) so as to produce a fluid barrier over the worksite W which is biased rearwards, e.g. over a larger proportion of the trench T (shown in Figure 5).

[0152] As shown in Figure 4, the illustrated underwater apparatus 200 takes the form of an underwater excavation apparatus.

[0153] The illustrated apparatus 200 takes the form of a controlled flow excavation apparatus. The apparatus 200 is configured and / or operable to produce a fluid flow at a pressure of typically around 35 kPa to 120 kPa and volume flow of typically around 1 m3 / s to 8 m3 / s. In contrast to mass flow excavation apparatus’, the higher pressure capability of the controlled flow excavation apparatus 200 means that the apparatus 200 is suitable for operation in both excavation (e.g., jetting) mode and also in a suction mode where the apparatus 200 may be used for collection and transportation of seabed material away from the worksite W.

[0154] However, it will be understood that the apparatus 200 may alternatively comprise or take the form of a mass flow excavation apparatus, a trailing suction hopper dredger, a cutter suction dredger, or other form of underwater apparatus.

[0155] As shown in Figure 4, the apparatus 200 comprises an inlet arrangement, generally denoted 202, and an outlet arrangement, generally denoted 204.

[0156] In the illustrated apparatus 200, the outlet arrangement 204 is axial i.e. co-linear with longitudinal axis B2 and comprises a single outlet 206 in the form of a nozzle.

[0157] In the illustrated apparatus 200, the inlet arrangement 202 comprises a single inlet 208. As shown in Figure 4, the inlet arrangement 202 is oriented at an angle to longitudinal axis B2.

[0158] The apparatus 200 comprises a rotor, generally denoted 210, comprising impellor blades 212 disposed around a hub 214. As shown in Figure 4, the hub 214 comprises a conical portion 216 which diverges the fluid flow as it enters the rotor 210. The rotor 210 is driven by a rotary drive arrangement 218. In the illustrated apparatus 200, the rotary drive arrangement 218 takes the form of an electric motor. However, it will be understood that the rotary drive arrangement 218 may take other forms such as a fluid-powered rotary drive in the form of a hydraulic motor, pneumatic motor or the like.

[0159] The apparatus 200 further comprises a stator, generally denoted 220. The stator 220 is configured and / or operable to direct the fluid flow exiting the rotor 210 to the outlet arrangement 204.

[0160] As shown, the stator 220 comprises static blades 222 extending from a hub 224. As shown in Figure 4, the hub 224 comprises conical portion 226 which converges the fluid flow towards the outlet arrangement 204.

[0161] As shown in Figure 4, the apparatus 200 further comprises a housing 228. In the illustrated apparatus 200, the inlet arrangement 202 and outlet arrangement 204 are integrally formed with the housing 228. However, it will be understood that the housing 228 and at least one of the inlet arrangement 202 and the outlet arrangement 204 may take the form of separate components.

[0162] As also shown in Figure 4, the apparatus 200 further comprises a coupling arrangement, generally denoted 230. In the illustrated apparatus 200, the coupling arrangement 230 comprises or takes the form of a mounting frame 232 into which the housings 38, 228 are mounted. However, it will be understood that the coupling arrangement 230 may take other forms. For example, the housing 228 may be directly coupled to the housing 38 or the housings 38, 228 may be integrally formed.

[0163] Referring now in particular to Figure 5, which shows a system 2000 for use in suppressing a sediment plume P, in use, the apparatus 200 is located above an underwater worksite W to be excavated with the outlet arrangement 204 oriented towards the seabed S. The rotary drive arrangement 218 is configured and / or operable to drive rotation of the rotor 210 so as to draw water surrounding the apparatus 200 into the inlet arrangement 202. The stator 220 is configured and / or operable to direct the fluid flow exiting the rotor 210 to the outlet arrangement 204. The fluid exiting the apparatus 200 forms an excavation jet J directed towards the worksite W so as to excavate trench T.

[0164] The device 10 is operable to receive, via the inlet arrangement 12, a fluid flow F in the form of water surrounding the device 10 and redirect the fluid flow F, via the outlet arrangement 14, so as to form a fluid barrier over the worksite W which inhibits the formation and / or movement of the sediment plume P.

[0165] As shown in Figure 5, in the illustrated apparatus 200 the device 10 is disposed ahead of the excavation jet J produced by the apparatus 200 and the device 10 is angled (i.e. arranged at a non-zero angle relative to vertical) so as to produce a fluid barrier over the worksite W which is biased towards the rear, e.g. over the trench T.

[0166] As shown in Figure 5, the apparatus 200 comprises a power conduit 234. The power conduit 234 is configured and / or operable to supply power to the apparatus 200, e.g. to the rotary drive arrangements 28, 218. In the illustrated apparatus 200, the power conduit 234 also forms a conveyance configured and / or operable to facilitate handling of the apparatus 200 from a surface facility V. As shown in Figure 5, the surface facility V takes the form of a dredging vessel or other suitable vessel.

[0167] Figure 6 and 7 of the accompanying drawings show diagrammatic views of an alternative apparatus, generally denoted 300, and system, generally denoted 3000, for use in the suppression of a sediment plume P.

[0168] The apparatus 300 is similar to the apparatus’ 100, 200 described above. As shown in Figures 6 and 7, the apparatus 300 comprises a device 10’ similar to the device 10 which is - as in the apparatus 200 - disposed ahead of the excavation jet J produced by the apparatus 300 and is angled (i.e. longitudinal axis A3 of device 10’ is arranged at a non-zero angle relative to vertical). However, in the device 10’ the outlet arrangement 14’ surrounds outlet arrangement 304, such that in use the fluid flow F exiting the device 10’ forms a circular fluid flow F around the excavation jet J. In the illustrated device 10’, the outlet 16’ is oriented so as to direct the fluid flow F towards and / or around the worksite W.

[0169] Beneficially, this has the effect of maintaining the range and / or power of the excavation jet J. As shown, although the apparatus 10’ is angled, the outlet arrangement 14’ is configured so that the fluid flow F exiting the device 10’ is output directly at the trench T - as in the apparatus 100 - and not biased towards the rear as in the apparatus 200. However, it will be understood that in other arrangements the outlet arrangement 14’ may be configured, e.g. angled, so that the fluid flow F exiting the device 10’ is biased towards the rear as in Figure 4.

[0170] As described above, the device 10’ comprises an outlet arrangement 14’ configured to redirect at least a portion of the fluid flow F received through the inlet arrangement 12’ so as to form a fluid barrier inhibiting the formation and / or movement of the sediment plume P, and in the illustrated device 10’ the outlet arrangement 14’ is configured to redirect all of the fluid flow F towards and / or around the worksite W.

[0171] In the illustrated device 10’, the outlet arrangement 14’ is annular and comprises a single annular or substantially annular outlet 16’.

[0172] Beneficially, the provision of an annular outlet arrangement 14’ facilitates the formation of a continuous or substantially continuous curtain of water exiting the device 10’ so as to form the fluid barrier over the worksite W.

[0173] In the illustrated device 10’, the outlet 16’ takes the form of a nozzle.

[0174] Beneficially, providing the outlet 16’ in the form of a nozzle facilitates the formation of a fluid jet - said fluid jet forming the fluid flow F - sufficient to suppress the sediment plume P.

[0175] In the illustrated device 10’, the outlet 16’ is oriented so as to direct the fluid flow F towards and / or around the worksite W in use.

[0176] Beneficially, the provision of an angled outlet arrangement 14’ facilitates the formation of a conical fluid barrier which prevents the upwards and lateral movement of the sediment plume P, thereby facilitating the suppression of the plume P. As described above, the device 10’ comprises an inlet arrangement 12’ for receiving therethrough the fluid flow F to be directed towards and / or around the worksite W.

[0177] In the illustrated device 10’, the inlet arrangement 12’ comprises a single inlet 18’. As shown in Figure 6, the inlet arrangement 12’ is oriented at an angle to longitudinal axis A3.

[0178] In order to draw the fluid flow F into the inlet arrangement 12’ and then direct it through the device 10’ to the outlet arrangement 14’, the device 10’ comprises a rotor, generally denoted 20’, comprising impellor blades 22’ disposed around a hub 24’. As shown in Figure 6, the hub 24’ comprises a conical portion 26’ which diverges the fluid flow F as it enters the rotor 20’.

[0179] The rotor 20’ is driven by a rotary drive arrangement 28’. In the illustrated device 10’, the rotary drive arrangement 28’ takes the form of an electric motor. However, it will be understood that the rotary drive arrangement 28’ may take other forms such as a fluid-powered rotary drive in the form of a hydraulic motor, pneumatic motor or the like.

[0180] The device 10’ further comprises a stator, generally denoted 30’. The stator 30’ is configured and / or operable to direct the fluid flow F exiting the rotor 20’ to the outlet arrangement 14’.

[0181] As shown, the stator 30’ comprises static blades 32’ extending from a hub 34’. As shown in Figure 6, the hub 34’ comprises conical portion 36’ which converges the fluid flow F towards the outlet arrangement 14’.

[0182] In use, the rotary drive arrangement 28’ is operable to drive rotation of the rotor 20’. The stator 30’ directs the fluid flow F exiting the rotor 20’ towards the outlet arrangement 14’.

[0183] As shown in Figure 6, the device 10’ further comprises a housing 38’. In the illustrated device 10’, the inlet arrangement 12’ and outlet arrangement 14’ are integrally formed with the housing 38’. However, it will be understood that the housing 38’ and at least one of the inlet arrangement 12’ and the outlet arrangement 14’ may take the form of separate components.

[0184] The illustrated underwater apparatus 300 takes the form of an underwater excavation apparatus.

[0185] The illustrated apparatus 300 takes the form of a controlled flow excavation apparatus. The apparatus 300 is configured and / or operable to produce a fluid flow at a pressure of typically around 35 kPa to 120 kPa and volume flow of typically around 1 m3 / s to 8 m3 / s. In contrast to mass flow excavation apparatus’, the higher pressure capability of the controlled flow excavation apparatus 300 means that the apparatus 300 is suitable for operation in both excavation (e.g., jetting) mode and also in a suction mode where the apparatus 300 may be used for collection and transportation of seabed material away from the worksite W.

[0186] However, it will be understood that the apparatus 300 may alternatively comprise or take the form of a mass flow excavation apparatus, a trailing suction hopper dredger, a cutter suction dredger, or other form of underwater apparatus.

[0187] As shown in Figure 6, the apparatus 300 comprises an inlet arrangement, generally denoted 302, and an outlet arrangement, generally denoted 304.

[0188] In the illustrated apparatus 300, the outlet arrangement 304 is axial i.e. co-linear with longitudinal axis B3 and comprises a single outlet 306 in the form of a nozzle.

[0189] In the illustrated apparatus 300, the inlet arrangement 302 comprises a single inlet 308. As shown in Figure 6, the inlet arrangement 302 is oriented at an angle to longitudinal axis B3.

[0190] The apparatus 300 comprises a rotor, generally denoted 310, comprising impellor blades 312 disposed around a hub 314. As shown in Figure 6, the hub 314 comprises a conical portion 316 which diverges the fluid flow as it enters the rotor 310.

[0191] The rotor 310 is driven by a rotary drive arrangement 318. In the illustrated apparatus 300, the rotary drive arrangement 318 takes the form of an electric motor. However, it will be understood that the rotary drive arrangement 318 may take other forms such as a fluid-powered rotary drive in the form of a hydraulic motor, pneumatic motor or the like.

[0192] The apparatus 300 further comprises a stator, generally denoted 320. The stator 320 is configured and / or operable to direct the fluid flow exiting the rotor 310 to the outlet arrangement 304.

[0193] As shown, the stator 320 comprises static blades 322 extending from a hub 324. As shown in Figure 6, the hub 324 comprises conical portion 326 which converges the fluid flow towards the outlet arrangement 304.

[0194] As shown in Figure 6, the apparatus 300 further comprises a housing 328. In the illustrated apparatus 300, the inlet arrangement 302 and outlet arrangement 304 are integrally formed with the housing 328. However, it will be understood that the housing 328 and at least one of the inlet arrangement 302 and the outlet arrangement 304 may take the form of separate components.

[0195] Referring now in particular to Figure 7, which shows the system 3000 for use in suppressing a sediment plume P, in use, the apparatus 300 is located above an underwater worksite W to be excavated with the outlet arrangement 304 oriented towards the seabed S. The rotary drive arrangement 318 is configured and / or operable to drive rotation of the rotor 310 so as to draw water surrounding the apparatus 300 into the inlet arrangement 302. The stator 320 is configured and / or operable to direct the fluid flow exiting the rotor 310 to the outlet arrangement 304. The fluid exiting the apparatus 300 forms an excavation jet J directed towards and / or around the worksite W so as to excavate trench T.

[0196] The device 10’ is operable to receive, via the inlet arrangement 12’, a fluid flow F in the form of water surrounding the device 10’ and redirect the fluid flow F, via the outlet arrangement 14’, so as to form a fluid barrier over the worksite W which inhibits the formation and / or movement of the sediment plume P.

[0197] As shown in Figure 7, the apparatus 300 comprises a power conduit 334. The power conduit 334 is configured and / or operable to supply power to the apparatus 300, e.g. to the rotary drive arrangements 28’, 318. In the illustrated apparatus 300, the power conduit 334 also forms a conveyance configured and / or operable to facilitate handling of the apparatus 300 from a surface facility V. As shown in Figure 7, the surface facility V takes the form of a dredging vessel or other suitable vessel.

[0198] Figures 8 and 9 of the accompanying drawings show diagrammatic views of an alternative device, generally denoted 410, and system, generally denoted 4000, for use in the suppression of a sediment plume P.

[0199] As shown in Figure 8, the device 410 comprises an outlet arrangement, generally denoted 414, configured to redirect at least a portion of the fluid flow F received through the inlet arrangement, generally denoted 412, so as to form a fluid barrier inhibiting the formation and / or movement of the sediment plume P, and in the illustrated device 410 the outlet arrangement 414 is configured to redirect a portion of the fluid flow F so as to form the fluid barrier and another portion, e.g. the remaining portion, of the fluid flow F in an axial direction so as to form excavation jet J.

[0200] Beneficially, the device 410 combines the plume suppression and excavation capabilities into a single device.

[0201] In the illustrated device 410, the outlet arrangement 414 comprises an annular or substantially annular outlet 416.

[0202] Beneficially, the provision of an annular outlet arrangement 414 facilitates the formation of a continuous or substantially continuous curtain of water exiting the device 410 so as to form the fluid barrier over the worksite W.

[0203] As shown in Figure 8, the outlet 416 is oriented at an angle a4 with respect to a central longitudinal axis A4 of the device 410 so as to direct the fluid flow F over and / or around the worksite W.

[0204] Beneficially, the provision of an angled outlet arrangement 414 facilitates the formation of a conical fluid barrier which prevents the upwards and lateral movement of the sediment plume P, thereby facilitating the suppression of the plume P. In the illustrated device 410, the outlet 416 takes the form of a nozzle, in particular a split nozzle so to facilitate the splitting of the fluid flow F.

[0205] Beneficially, providing the outlet 416 in the form of a nozzle facilitates the formation of a fluid jet - said fluid jet forming the fluid flow F - sufficient to suppress the sediment plume P and excavate the worksite W.

[0206] In the illustrated device 410, the outlet 416 is oriented so as to direct the fluid flow F towards and / or around the worksite W in use.

[0207] In the device 410, however, the outlet arrangement 414 further comprises an axial outlet 440 for directing the portion, e.g. remaining portion, of the fluid flow F axially from the device 410 so as to form the excavation jet J. As shown in Figure 8, the axial outlet 440 is oriented so that the fluid flow F is co-linear with the longitudinal axis A4.

[0208] As described above, the device 410 comprises an inlet arrangement 412 for receiving therethrough the fluid flow F to be directed towards and / or around the worksite W.

[0209] In the illustrated device 410, the inlet arrangement 412 comprises a single inlet 418. As shown in Figure 8, the inlet arrangement 412 is oriented at an angle to longitudinal axis A4.

[0210] In order to draw the fluid flow F into the inlet arrangement 412 and then direct it through the device 410 to the outlet arrangement 414, the device 410 comprises a rotor, generally denoted 420, comprising impellor blades 422 disposed around a hub 424. As shown in Figure 8, the hub 424 comprises a conical portion 426 which diverges the fluid flow F as it enters the rotor 420.

[0211] The rotor 420 is driven by a rotary drive arrangement 428. In the illustrated device 410, the rotary drive arrangement 428 takes the form of an electric motor. However, it will be understood that the rotary drive arrangement 428 may take other forms such as a fluid-powered rotary drive in the form of a hydraulic motor, pneumatic motor or the like. The device 410 further comprises a stator, generally denoted 430. The stator 430 is configured and / or operable to direct the fluid flow F exiting the rotor 420 to the outlet arrangement 414.

[0212] As shown, the stator 430 comprises static blades 432 extending from a hub 434. As shown in Figure 8, the hub 434 comprises conical portion 436 which converges the fluid flow F towards the outlet arrangement 414.

[0213] In use, the rotary drive arrangement 428 is operable to drive rotation of the rotor 420. The stator 430 directs the fluid flow F exiting the rotor 420 towards the outlet arrangement 414.

[0214] As shown in Figure 8, the device 410 further comprises a housing 438. In the illustrated device 410, the inlet arrangement 412 and outlet arrangement 414 are integrally formed with the housing 438. However, it will be understood that the housing 438 and at least one of the inlet arrangement 412 and the outlet arrangement 414 may take the form of separate components.

[0215] Referring now in particular to Figure 9, which shows the system 4000 for use in suppressing a sediment plume P, in use, the device 410 is located above an underwater worksite W to be excavated with the outlet arrangement 414 oriented towards the seabed S. The rotary drive arrangement 428 is configured and / or operable to drive rotation of the rotor 420 so as to draw water surrounding the apparatus 410 into the inlet arrangement 412. The stator 430 is configured and / or operable to direct the fluid flow F exiting the rotor 412 to the outlet arrangement 414. The fluid flow F exiting the apparatus 410 via outlet 416 forms a fluid barrier over the worksite W which inhibits the formation and / or movement of the sediment plume P while the fluid flow F exiting the apparatus 410 via outlet 440 forms an excavation jet J directed towards the worksite W so as to excavate trench T.

[0216] As shown in Figure 9, the device 410 comprises a power conduit 434. The power conduit 434 is configured and / or operable to supply power to the device 410, e.g. to the rotary drive arrangement 428. In the illustrated device 410, the power conduit 434 also forms a conveyance configured and / or operable to facilitate handling of the device 410 from a surface facility V. As shown in Figure 9, the surface facility V takes the form of a dredging vessel or other suitable vessel.

[0217] As described above, various modifications may be made without departing from the scope of the invention.

[0218] Figures 10 and 11 of the accompanying drawings show diagrammatic views of an alternative device, generally denoted 510, and system, generally denoted 5000, for use in the suppression of a sediment plume P.

[0219] As shown in Figure 10, the device 510 comprises an outlet arrangement, generally denoted 514, configured to redirect at least a portion of the fluid flow F received through the inlet arrangement, generally denoted 512, so as to form a fluid barrier inhibiting the formation and / or movement of the sediment plume P, and in the illustrated device 510 the outlet arrangement 514 is configured to redirect a portion of the fluid flow F so as to form the fluid barrier and another portion, e.g. the remaining portion, of the fluid flow F in an axial direction so as to form excavation jet J.

[0220] Beneficially, the device 510 combines the plume suppression and excavation capabilities into a single device.

[0221] While the device 410 comprises a single annular outlet 416, in the illustrated device 510 the outlet arrangement 514 comprises a plurality of outlets 516.

[0222] As shown in Figure 10, the outlets 516 are oriented at 90 degrees or substantially 90 degrees with respect to a central longitudinal axis A5 of the device 510 so as to direct the fluid flow F radially.

[0223] In the illustrated device 510, the outlet 516 takes the form of a nozzle, in particular a split nozzle so to facilitate the splitting of the fluid flow F.

[0224] Beneficially, providing the outlet 516 in the form of a nozzle facilitates the formation of a fluid jet - said fluid jet forming the fluid flow F - sufficient to suppress the sediment plume P and excavate the worksite W. In the device 510, the outlet arrangement 514 further comprises an axial outlet 540 for directing the portion, e.g. remaining portion, of the fluid flow F axially from the device 510 so as to form the excavation jet J. As shown in Figure 10, the axial outlet 540 is oriented so that the fluid flow F is co-linear with the longitudinal axis A5.

[0225] As described above, the device 510 comprises an inlet arrangement 512 for receiving therethrough the fluid flow F to be directed towards and / or around the worksite W.

[0226] In the illustrated device 510, the inlet arrangement 512 comprises a single inlet 518. As shown in Figure 10, the inlet arrangement 512 is oriented at an angle to longitudinal axis A5.

[0227] In order to draw the fluid flow F into the inlet arrangement 512 and then direct it through the device 510 to the outlet arrangement 514, the device 510 comprises a rotor, generally denoted 520, comprising impellor blades 522 disposed around a hub 524. As shown in Figure 10, the hub 524 comprises a conical portion 526 which diverges the fluid flow F as it enters the rotor 520.

[0228] The rotor 520 is driven by a rotary drive arrangement 528. In the illustrated device 510, the rotary drive arrangement 528 takes the form of a hydraulic motor. However, it will be understood that the rotary drive arrangement 528 may take other forms such as an electric motor or an alternative fluid-powered rotary drive in the form of a pneumatic motor or the like.

[0229] The device 510 further comprises a stator, generally denoted 530. The stator 530 is configured and / or operable to direct the fluid flow F exiting the rotor 520 to the outlet arrangement 514.

[0230] As shown, the stator 530 comprises static blades 532 extending from a hub 534. As shown in Figure 10, the hub 534 comprises conical portion 536 which converges the fluid flow F towards the outlet arrangement 514. In use, the rotary drive arrangement 528 is operable to drive rotation of the rotor 520. The stator 530 directs the fluid flow F exiting the rotor 520 towards the outlet arrangement 514.

[0231] As shown in Figure 10, the device 510 further comprises a housing 538. In the illustrated device 510, the housing 538, inlet arrangement 512 and outlet arrangement 514 take the form of separate components. However, it will be understood that the housing 538 and at least one of the inlet arrangement 512 and the outlet arrangement 514 may be integrally formed.

[0232] Referring now in particular to Figure 11 , which shows the system, generally denoted 5000. for use in suppressing a sediment plume P, in use, the device 510 is located above an underwater worksite W to be excavated with the outlet arrangement 514 oriented towards the seabed S. The rotary drive arrangement 528 is configured and / or operable to drive rotation of the rotor 520 so as to draw water surrounding the apparatus 510 into the inlet arrangement 512. The stator 530 is configured and / or operable to direct the fluid flow F exiting the rotor 520 to the outlet arrangement 514. The fluid flow F exiting the apparatus 510 via outlet 516 forms a fluid barrier over the worksite W which inhibits the formation and / or movement of the sediment plume P while the fluid flow F exiting the apparatus 510 via outlet 540 forms an excavation jet J directed towards the worksite W so as to excavate trench T.

[0233] As shown in Figure 11 , the device 510 comprises a power conduit 534. The power conduit 534 is configured and / or operable to supply power to the device 510, e.g. to the rotary drive arrangement 528. In the illustrated device 510, the power conduit 534 also forms a conveyance configured and / or operable to facilitate handling of the device 510 from a surface facility V. As shown in Figure 11 , the surface facility V takes the form of a dredging vessel or other suitable vessel.

[0234] Referring now to Figure 12 of the accompanying drawings, there is shown a system, generally denoted 6000, for use in the suppression of a sediment plume P.

[0235] As shown in Figure 12, the system 6000 comprises a vessel V having a suction tube 6002 which reaches down onto the seabed S and which is configured and / or operable to suck up large quantities of seabed material into tanks 6004 (shown in dotted line in Figure 12). At the distal end of the suction tube 6002 is a suction head 6006. In the illustrated system 6000, the suction head 6006 comprises or takes the form of a passive drag cutter. However, it will be understood that the suction head 6006 may take other forms, such as a system of high-pressure jets, or a rotating mechanical cutter. The suction head 6006 is configured and / or operable to break up the seabed material allowing it to be sucked into the suction tube 6002. A proportion of this seabed material, typically 20 to 30% and in the case of harder formations typically up to 50%, may escape the suction of the suction head 6006, resulting in a sediment plume P.

[0236] As shown in Figure 12, the system 6000 comprises a device, generally denoted 6010, for use in the suppression of the plume P. In the illustrated system 6000, the device 6010 is similar to the device 10. However, it will be understood that the device 6010 may take other suitable forms.

[0237] It will be recognised that the devices’, apparatus’ and systems’ of the present disclosure are not limited to underwater excavation operations and may be utilised as part of, or in combination with a number of different underwater apparatus’, in a variety of underwater construction and / or decommissioning operations.

Claims

CLAIMS1 . A device for use in the suppression of a sediment plume, the device comprising: an inlet arrangement for receiving therethrough a fluid flow; and an outlet arrangement comprising one or more outlets for directing said fluid flow out from the device, wherein the device is configured to redirect at least a portion of the fluid flow received through the inlet arrangement so as to form a fluid barrier inhibiting the formation and / or movement of the sediment plume.

2. The device of claim 1 , wherein the device is configured to redirect at least a portion of the fluid flow: in a lateral or substantially lateral direction; in a forward or substantially forward direction; and / or in a rearward or substantially rearward direction.

3. The device of claim 1 or 2, wherein the outlet arrangement comprises a single outlet.

4. The device of claim 3, wherein the outlet is annular or substantially annular.

5. The device of claim 1 or 2, wherein the outlet arrangement comprises a plurality of outlets.

6. The device of claim 5, wherein the outlets are circumferentially arranged and / or spaced.

7. The device of any preceding claim, wherein at least one of: at least one of the one or more outlets of the outlet arrangement are oriented radially; and at least one of the one or more outlets of the outlet arrangement are angled with respect to the horizontal.

8. The device of any preceding claim, wherein at least one of the one or more outlets of the outlet arrangement comprises or takes the form of a nozzle.

9. The device of any preceding claim, wherein the device is oriented so that the inlet arrangement is disposed at a non-zero angle with respect to vertical.

10. The device of any preceding claim, wherein the device is configured and / or operable to redirect all of the fluid flow so as to form the fluid barrier.

11. The device of any one of claims 1 to 9, wherein the device is configured and / or operable to direct a portion of the fluid flow so as to form the fluid barrier and another portion, e.g. a remaining portion, of the fluid flow in an axial direction.

12. The device of any preceding claim, comprising a rotor.

13. The device of any preceding claim, comprising a stator.

14. The device of any preceding claim, comprising a rotary drive arrangement.

15. The device of claim 14, wherein the rotary drive arrangement comprises a rotary drive which comprises or takes the form of: an electric rotary drive, e.g. an electric motor; a fluid-powered rotary drive, e.g. a hydraulic motor or pneumatic motor.

16. The device of any preceding claim, comprising a housing.

17. The device of claim 16, wherein at least one of the inlet arrangement and the outlet arrangement are integrally formed with the housing.

18. The device of claim 16, wherein at least one of the inlet arrangement and the outlet arrangement are coupled to the housing.

19. An underwater apparatus comprising the device of any one of claims 1 to 18.

20. The underwater apparatus of claim 19, wherein the underwater apparatus comprises or takes the form of an underwater excavation apparatus.

21. The underwater apparatus of claim 20, wherein the underwater excavation apparatus comprises or take the form of one of: a mass flow excavation apparatus; and a controlled flow excavation apparatus.

22. The underwater apparatus of claim 20, wherein the underwater apparatus comprises or takes the form of: a dredging apparatus; an underwater mining apparatus; an underwater drilling apparatus; or an underwater pile-driving apparatus.

23. The underwater apparatus of any one of claims 19 to 22, wherein the underwater apparatus comprises: a rotor; a stator; a rotary drive arrangement.

24. An underwater system comprising: the device of the first aspect; and / or the apparatus of the second aspect.

25. A method for suppression of a sediment plume using the device of any of claims 1 to 18, the underwater apparatus of any one of claims 19 to 23; and / or the system of claim 24.

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