Pressure exchange chamber

Abstract

A pressure exchange chamber comprises: a pressure exchange chamber pipe (12) extending around a perimeter; a driving fluid input valve (44) and a driving fluid output valve (46), both valves being enclosed by the pressure exchange chamber pipe; and a slurry input valve (34) and a slurry output valve (36), both valves being enclosed by the pressure exchange chamber pipe. A hydraulic ore hoisting system (HOHS) for use at sea comprising a plurality of such pressure exchange chambers is also disclosed.

Description

Technical Field

[0001] The present invention relates to a pressure exchange chamber. In particular, although not exclusively, the present invention relates to a pressure exchange chamber for use in the mining and minerals processing industry, and particularly for use in a hydraulic ore hoisting system (HOHS) for locating on or near a sea or lake bed.Background

[0002] In the minerals processing industry, one problem relates to transporting ore from underground or subsea locations to a surface level. A novel system for such transportation has been described in PCT application number PCT / IB2019 / 055957, in the name of Weir Minerals Netherlands B.V., and is referred to as an HOHS. Other types of HOHS are also available.

[0003] The HOHS described in PCT / IB2019 / 055957 requires a pressure exchange chamber system as illustrated in Fig. 1. The pressure exchange chamber system 1 comprises a plurality of pressure exchange chambers 2,3,4 extending for a significant distance, for example many tens of metres, between a driving fluid (or water) input end 5 and a slurry output end 6. Each pressure exchange chamber includes a set of water valves 7 at the driving fluid input end 5 and a set of slurry valves 8 at the slurry output end 6. The pressure exchange chambers 2,3,4 are illustrated in Fig. 1 in a linear arrangement. However, when deployed in a deep sea environment, the pressure exchange chamber system 1 (and therefore the pressure exchange chambers 2,3,4) are expected to be dropped through a moonpool (an aperture in the hull of a ship) and lifted from the sea bed back through the moonpool. The size of the moonpool dictates the maximum dimensions of the pressure exchange chamber system 1. It is therefore difficult to design a pressure exchange system that can be deployed through a moonpool and yet has a sufficiently long chamber length (typically over 60m long, sometimes over 100m or 150m long) for the HOHS to work effectively.

[0004] Furthermore, for flow assurance and system reliability in an HOHS, the pressure exchange chambers are ideally linear pump chambers disposed in a horizontal plane with no height difference between the water input end and the slurry output end. Pressure exchange chambers having multiple bends increase the degradation of polymetallic nodules being transported in the slurry. Any gradient, or height difference, along a pressure exchange chamber increases the risk of a blockages in that chamber.

[0005] It is among the objects of an embodiment of the present invention to obviate or mitigate the above disadvantage or other disadvantages of the prior art or to provide a useful alternative to the prior art, or improved operation thereof.

[0006] The various aspects detailed hereinafter are independent of each other, except where stated otherwise; however, unless it is technically unfeasible, features of one aspect may be combined with any of the other aspects to create new aspects. Any claim corresponding to one aspect should not be construed as incorporating any element or feature of the other aspects unless explicitly stated in that claim.

[0007] Reference in this specification to any prior publication (or information derived from the prior publication), or to any matter which is known, is not, and should not be taken as an acknowledgment or admission or any form of suggestion that the prior publication (or information derived from the prior publication) or known matter forms part of the common general knowledge in the field of endeavour to which this specification relates, or is even citable as prior art against this application.

[0008] WO 2020 / 016716 A2 discloses a pumping system comprising at least one pressure exchange chamber.Summary of Disclosure

[0009] This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter.

[0010] According to a first aspect, there is provided a pressure exchange chamber as set forth in claim 1.

[0011] The pressure exchange chamber pipe may extend completely around a perimeter so that it fully encloses the driving fluid and slurry valves; alternatively, the pressure exchange chamber pipe may extend around a substantial portion of a perimeter so that it substantially encloses those valves (leaving only a relatively small gap).

[0012] The driving fluid valves and the slurry valves may be generally centrally located within the pressure exchange chamber pipe. The slurry input valve may be located centrally and the driving fluid valves may be located on opposing sides of the slurry input valve.

[0013] The slurry valves may be located between a first set of driving fluid valves and a second set of driving fluid valves.

[0014] The pressure exchange chamber pipe may be substantially uniformly disposed around the driving fluid valves and / or the slurry valves; thereby providing a generally central centre of gravity for the pressure exchange system. A generally central centre of gravity facilitates deployment of the pressure exchange chamber through a moonpool of the surface vessel or from another type of floating system. By having a generally central centre of gravity, a hook-up attachment, which is coupled to a riser extending from the pressure exchange chamber, minimises tilting of the pressure exchange chamber during operation and deployment. This ensures that there is a balanced operating state for the pressure exchange chamber.

[0015] The pressure exchange chamber may further comprise a driving fluid riser coupling and a slurry input pipe, both pipes being enclosed by the pressure exchange chamber pipe.

[0016] The pressure exchange chamber may further comprise a driving fluid output pipe and a slurry output pipe, both pipes being enclosed by the pressure exchange chamber pipe and optionally coupled to a portion of the valves.

[0017] According to a second aspect of the present invention there is provided a pressure exchange chamber system comprising: a central frame; and a plurality of pressure exchange chambers according to the first aspect, wherein the pressure exchange chamber pipes are arranged in stacked planes around the central frame, and each of the plurality of sets of driving fluid input and output valves and slurry input and output valves are associated with a respective pressure exchange chamber pipe; and the sets of driving fluid and slurry valves are supported by the central frame.

[0018] The pressure exchange chamber pipes are preferably arranged in generally horizontal planes that are vertically stacked in registration with each other. By having a pipe arranged in a generally horizontal plane, the bends in that pipe are in a horizontal plane and preferably have the same diameter, which should reduce the risk of blockage.

[0019] The pressure exchange chamber system optionally comprises a driving fluid input pipe and a slurry input pipe. The driving fluid input pipe may comprise, or couple to, a marine pipe (or riser) extending from a surface of the sea to the pressure exchange chamber system. The slurry input pipe may couple to a slurry feed pump.

[0020] The pressure exchange chamber system optionally comprises a driving fluid output pipe and a slurry output pipe. The slurry output pipe may comprise, or couple to, a marine riser extending from the pressure exchange chamber system to the surface of the sea.

[0021] The driving fluid and slurry input and output pipes may be located within the central frame near to a centre of gravity of the pressure exchange chamber system; thereby facilitating deployment of the pressure exchange chamber system through a moonpool of a surface vessel, such as a ship. It also aids recovery of the system through the same size of moonpool.

[0022] Each driving fluid input and output valve (of the same PEC) may have an associated compression and decompression valve, and these compression and decompression valves may be located in line with, and at generally the same height as, the associated driving fluid input and output valves.

[0023] Each driving fluid input and output valve (of the same PEC) may be located at a similar vertical position (height) to the corresponding slurry output valve, and a similar vertical position (height) to the corresponding slurry input valve. Alternatively, each driving fluid input and output valve (of the same PEC) may be vertically offset from the corresponding slurry output valve, and the corresponding slurry input valve.

[0024] One set of driving fluid valves (for one PEC) may be located at a similar vertical position to another set of driving fluid valves (for another PEC).

[0025] One set of driving fluid valves (for one PEC) may be vertically offset from another set of driving fluid valves (for another PEC). Similarly, one set of slurry valves may be vertically offset from another set of slurry valves.

[0026] The pressure exchange chamber system optionally comprises a driving fluid input manifold, a driving fluid output manifold, a slurry input manifold and a slurry output manifold.

[0027] The driving fluid input manifold may comprise a vertically extending pipe and a plurality of pipe segments extending downwardly therefrom, each downwardly extending pipe segment being coupled at the lower end to a respective driving fluid input valve.

[0028] The slurry input valves may be located centrally and the driving fluid valves may be located on opposing sides of the slurry input valves, thereby minimising the length of the common slurry input manifold.

[0029] The driving fluid output manifold may comprise a vertically extending pipe and a plurality of pipe segments extending upwardly therefrom, each upwardly extending pipe segment being coupled at the upper end to a respective driving fluid output valve.

[0030] The slurry input manifold may comprise a vertically extending pipe and a plurality of pipe segments extending upwardly therefrom, each upwardly extending pipe segment being coupled at the upper end to a respective slurry input valve. By having the pipe segments disposed in an upward direction towards the slurry input valve, when the slurry input flow is halted, any slurry in the pipe segment flows downwards (as a result of gravity) and away from the slurry input valve. This reduces the risk of blocking the slurry input valve.

[0031] The slurry output manifold may comprise a vertically extending pipe and a plurality of pipe segments extending downwardly therefrom, each downwardly extending pipe segment being coupled at the lower end to a respective slurry output valve.

[0032] Each pressure exchange chamber pipe may define a generally rectangular (in some embodiments a generally square) shape, having bends at the corners to reduce particle size degradation, wear of the pipe, and blockages.

[0033] Each pressure exchange chamber pipe may comprise a thermoplastic composite pipe (TCP). Alternatively, each pressure exchange chamber pipe may comprise a metal (such as steel) pipe. Advantages of a TCP include lighter weight than steel, corrosion resistance, and improved flexibility for fabricating bends therein, compared with metals.

[0034] Optionally, each TCP comprises a circular cross-section.

[0035] Each pressure exchange chamber pipe may be coated on an inner surface with a wear resistant coating.

[0036] Each pressure exchange chamber pipe may be relatively long, for example, 40m, 50m, 60m, 70m, 80m, 90m or 100m, 125m or 160m in length.

[0037] The pressure exchange chamber system may have a footprint of approximately 10m x 20m (length by width) for its outer dimensions.

[0038] The pressure exchange chamber system may further comprise one or more hydraulic power units and slurry feed pumps (a plurality of one or both may be provided for redundancy purposes), a control cabinet, pressure relief systems, flow sensors, buoyancy, thrust positioning equipment to move the pressure exchange chamber system, and the like. The power unit and pump may be marinised to enable them to be operated on or near a sea bed.

[0039] The central frame may include a perimeter framework surrounding a core of the central frame. The core may be used to mount the valves. The perimeter framework may be disposed primarily in a horizontal plane. The perimeter framework may include a plurality of upright lattices spaced around the perimeter framework, each lattice defining a plurality of spaces. Each lattice space may be used to support one or more pressure exchange chamber pipe. The perimeter framework may be cantilevered from the core.

[0040] According to a third aspect there is provided a hydraulic ore hoisting system including the pressure exchange chambers according to the second aspect.

[0041] It will now be appreciated that a pressure exchange system can be provided that can easily be deployed through a moonpool on a surface vessel on the sea or a lake, with improved balance and geometry.

[0042] One advantage of a rectangular shaped PEC system is that the contour or shape is substantially the same as that of a typical shape of the moonpool of a mining vessel. This means that handling and transporting the PEC system onto and around a deck of a mining vessel and into the moonpool can typically be performed using known subsea equipment handling systems e.g. transporters, guidance systems, carriers, and the like.Brief Description of Figures

[0043] Fig. 1 is a simplified schematic diagram of a prior art pressure exchange chamber system. The above aspects, and other aspects, will be apparent from the following specific description, given by way of example only, with reference to the accompanying drawings, in which: Fig. 2 is a simplified pictorial cut-away perspective view of a pressure exchange chamber system according to a first embodiment of the present invention, mounted in a frame with ancillary units; Fig. 3 is a simplified schematic plan view of parts (driving fluid, compression, decompression, and slurry valves) shown in the pressure exchange chamber system of Fig. 2; Fig. 4 is a simplified schematic plan view of the valves shown in Fig. 3, including their interconnections; Fig. 5 is a simplified perspective view of the valves of Fig. 4; Fig. 6 is a pictorial perspective view of a slurry input manifold for the slurry valves of Fig. 3 to 5; Fig. 7 is a plan view of a part (one of the pressure exchange chamber pipes) of the pressure exchange chamber system of Fig. 2; Fig. 8 is a perspective view of the pressure exchange chamber pipe of Fig. 7; Fig. 9 is a pictorial perspective view of the pressure exchange chambers of the pressure exchange chamber system of Fig. 2; Fig. 10A is a pictorial perspective view of the valves of Fig. 5, with one (a highest) pressure exchange chamber pipe connected; Fig. 10B is a pictorial perspective view of the valves of Fig. 5, with another (a second highest) pressure exchange chamber pipe connected; Fig. 10C is a pictorial perspective view of the valves of Fig. 5, with yet another (a second lowest) pressure exchange chamber pipe connected; Fig. 10D is a pictorial perspective view of the valves of Fig. 5, with yet another (a lowest) pressure exchange chamber pipe connected; Fig. 11 is a simplified pictorial perspective view of another embodiment of pressure exchange chambers; Fig. 12 is a simplified pictorial perspective view of yet another embodiment of pressure exchange chambers; Fig. 13 is a simplified pictorial perspective view of still another embodiment of pressure exchange chambers. Detailed Description

[0044] Reference is first made to Fig. 2, which is a simplified, partially cut-away, pictorial perspective view of a pressure exchange chamber ("PEC") system 10 according to a first embodiment of the present invention. The PEC system 10 comprises a plurality of pressure exchange chambers ("PECs") 12a, b, c, d. In this embodiment, four PECs 12a, b, c, d are provided. Typically, only three of these PECs (e.g. 12a, b, c) are used, with the fourth PEC (e.g. 12d) being kept in reserve in case one of the three PECs (12a, b, c) fails. This provides redundancy for continued operation, which is important because it may be difficult to repair the PEC system 10 in situ on a seabed. The PECs are designed for use in a deep sea environment and may be coupled to a lower part of a riser, an umbilical or cable, or similar.

[0045] Each PEC 12a, b, c, d comprises a PEC pipe 14a, b, c, d extending around a perimeter in a generally rectangular-spiral shape (a spiral having substantially straight-sides and bends at the end of the straight sides). The rectangular-spiral shape may comprise a square-spiral shape in some embodiments. The PEC pipes 14a, b, c, d are arranged in vertically spaced stacked planes (each plane being generally horizontal) around a central frame 16. In this embodiment, the central frame 16 comprises welded steel beams, but different materials and couplings may be used in other embodiments.

[0046] The central frame 16 includes a cuboid central core 18 having lateral support wings 20 (only one is shown) extending therefrom, and frame extensions (also referred to as a perimeter framework) 22 cantilevered from the lateral support wings 20. The frame extensions 22 support a plurality of upright lattices 24 spaced around the perimeter framework 22, each lattice 24 defining an array of spaces. Corresponding spaces in the upright lattices 24 are aligned so that a PEC pipe (e.g. 14a) can be routed through the aligned spaces in the upright lattices 24. Each lattice space supports one or more PEC pipe 14; typically, two PEC pipes (e.g. 14a and 14b) are routed through each lattice space.

[0047] Each PEC pipe 14 comprises a thermoplastic composite pipe (TCP) and extends for approximately 160m and has a footprint of approximately 30m x 20m (length by width) for its outer dimensions.

[0048] The PEC system 10 further comprises a hydraulic power unit 26 and a slurry feed pump 28 (for feeding slurry into the PEC pipes 14). Both the hydraulic power unit 26 and the feed pump 28 are coupled to the central frame 16 and are designed for operating in deep sea water environments (i.e. they are marinised). In this embodiment, two hydraulic power units 26 and slurry feed pumps 28 are provided in case of failure of either during use, but these additional units are not illustrated in the drawings.

[0049] Each PEC 12a, b, c, d also comprises associated valves, which will now be described in detail with reference to Figs. 3 to 6. The valves are arranged in a block valve arrangement 30, a central portion 32 of which contains slurry valves (four slurry input valves 34a, b, c, d and four slurry output valves 36a, b, c, d; one for each PEC) located within the cuboid central core 18.

[0050] The block valve arrangement 30 includes two side portions 40, 42. These side portions 40, 42 are mounted on opposing lateral support wings 20.

[0051] The first side portion 40 includes: two driving fluid (or water) input valves 44a, b; two driving fluid (or water) output valves 46a, b; two compression valves 48a, b; and two decompression valves 50a, b.

[0052] Similarly, the second side portion 42 includes: two driving fluid (or water) input valves 44c, d; two driving fluid (or water) output valves 46c, d; two compression valves 48c, d; and two decompression valves 50c, d.

[0053] The valves in the second side portion 42 are generally located at a higher level (i.e. above) the valves in the first side portion 40 (best seen in Fig. 5) and are arranged in a mirror image manner to the valves in the first side portion 40.

[0054] The block valve arrangement 30 is used for controlling pressure and fluid flow through the PEC pipes 14 (i.e. initially allowing the slurry feed pump 28 to fill a PEC pipe 14, then allowing a PD pump to drive out the slurry from the PEC pipe).

[0055] As best seen in Fig. 4, the input and output of each PEC 12a, b, c, d is arranged in a quadrant of the block valve arrangement 30. The input and output of the first PEC 12a are in the upper left quadrant; the input and output of the second PEC 12b are in the lower left quadrant; the input and output of the third PEC 12c are in the lower right quadrant; the input and output of the fourth PEC 12d are in the upper right quadrant.

[0056] A single slurry output pipe coupling 60 is located in the central portion 32 and extends upwards to meet and couple to a riser (not shown) that raises the slurry pumped out of the PEC system 10 to a dewatering system, for example, on deck of a ship on the sea surface. Similarly, a single driving fluid riser coupling 62 is located in the central portion 32 and extends upwards to meet and couple to a driving fluid riser (not shown) that couples to a pump (not shown) on a surface of the sea. The single driving fluid riser coupling 62 may coupled to a riser type of pipe that extends to the surface of the sea.

[0057] A first driving fluid output pipe 64 is provided for the first and second PEC valves (i.e. at the first and second quadrants) and extends downwards therefrom. Similarly, a second driving fluid output pipe 66 is provided for the third and fourth PEC valves (i.e. at the third and fourth quadrants) and extends downwards therefrom. These driving fluid output pipes 64, 66 are best seen in Fig. 5. In other embodiments, they could be combined as a single driving fluid output pipe.

[0058] A single slurry input pipe 68 (best seen in Fig. 5) is located in the central portion 32 and couples to the four slurry input valves 34a, b, c, d via a slurry input manifold 70 (best seen in Fig. 6). The single slurry input pipe 68 is coupled to the slurry feed pump 28, which fills the PEC pipes 14 with slurry.

[0059] The slurry input manifold 70 includes a slurry input connecting pipe 72 (that couples to the slurry input pipe 68), and a plurality of angled pipe segments 74a, b, c, d extending upwardly and outwardly therefrom. Each upwardly angled pipe segment 74a, b, c, d is coupled at an upper end thereof to a respective slurry input valve 34a, b, c, d. By arranging the pipe segments 74a, b, c, d in an upward (and outward) direction towards the slurry input valves 34a, b, c, d, when the slurry input flow is halted, any slurry in the pipe segment 74 flows downwards (as a result of gravity) and away from the associated slurry input valve 34. This reduces the risk of blocking the slurry input valves 34a, b, c, d or damaging them when they are closed.

[0060] The operation (e.g. opening and closing) of the various valves in the block valve arrangement 30 are controlled by the subsea hydraulic power unit 26.

[0061] Pulsation dampeners 80 are also provided on the single driving fluid input pipe 62 (best seen in Figs. 4 and 5). This may be implemented using a common driving fluid manifold that feeds the four PECs 12.

[0062] Reference is now made to Figs. 7 and 8, which show two views of one of the PEC pipes 14a. One end of the PEC pipe 14a is the slurry end 82 that is coupled to a slurry pipe 84a. The slurry pipe 84a is coupled to both the slurry input valve 34a (which is opened when the PEC pipe 14a is being filled with slurry) and the slurry output valve 36a (which is opened when slurry is being discharged from the PEC pipe 14a and up the slurry output pipe coupling 60 to the riser). The other end of the PEC pipe 14a is the driving fluid end 86 that is coupled to a driving fluid pipe 88a. The driving fluid pipe 88a is coupled to both the driving fluid input valve 44a (which is opened when slurry is being discharged from the PEC pipe 14a and up the slurry output pipe coupling 60 to the riser) and the driving fluid output valve 46a (which is opened when the PEC pipe 14a is being filled with slurry). Arrows 90 indicate the direction of slurry flowing into the PEC pipe 14a; whereas, arrows 92 indicate the direction of slurry flowing out of the PEC pipe 14a and towards the slurry output pipe 60. The PEC pipe 14a rises (is inclined) at the driving fluid end 86 and then extends in a rectangular-spiral in a horizontal plane. By having the inclined portion at the driving fluid end 86 there is reduced risk of blockage because it is primarily driving fluid (which does not contain nodules or large particles) that passes through this part rather than slurry.

[0063] Fig. 9 is a pictorial perspective view showing the four PEC pipes 14a, b, c, d of Fig. 2 vertically stacked and surrounding the block valve arrangement 30. The PEC pipe 14 is substantially uniformly disposed around the block valve arrangement 30, thereby ensuring that the PEC system 10 has a centre of gravity close to its geometric centre. This facilitates deployment of the PEC system 10 through a moonpool of a surface ship (not shown). This also ensures that the PEC system 10 is maintained in a generally level position (minimising any tilt) during operation.

[0064] The PEC system 10 comprises a plurality (four in this embodiment) of PECs 12a, b, c, d, arranged in stacked planes, vertically offset from each other. This is best seen in Figs. 10A through 10D, which are pictorial perspective views similar to that of Fig. 9, but each only shows one of the PEC pipes 14a, b, c, d on its own, for further clarity.

[0065] Each PEC pipe 14a, b, c, d is disposed in a generally horizontal plane. The planes are generally, but not exactly, horizontal, because each chamber pipe 14a, b, c, d rises slightly from the respective driving fluid end 86a, b, c, d to the height of the respective slurry end 82a, b, c, d to provide space for the pipe 14 to continue to enclose the block valve arrangement 30 in a generally rectangular-spiral shape (a spiral having substantially straight-sides and bends at the end of the straight sides). In this embodiment each PEC pipe 14a, b, c, d rises to the level of the respective driving fluid end 86a, b, c, d before the first bend in the PEC pipe 14a, b, c, d.

[0066] It should now be appreciated that this PEC system 10 has the following advantages: (i) a centre of gravity near the centre of the PEC system 10, (ii) a relatively small footprint while enabling the PEC pipes 14 to be very long, and (iii) a relatively small number of bends in each PEC pipe 14.

[0067] It should be appreciated that other PEC system configurations are possible within the scope of the claims. For example, Fig. 11 shows another arrangement (simplified by removing the compression and decompression valves for clarity) of PECs 112 in which the block valve arrangement 130 is different, but the PEC pipes 14a, b, c, d are identical or very similar to those of PEC system 10.

[0068] Fig. 12 shows a third PEC system 212 in which the block valve arrangement 230 is different, and the PEC pipes 214a, b, c, d are also different to those of PEC system 10. The block valve arrangement 230 is split, with slurry input 234 and output 236 valves being located as a block 230a within, and enclosed by, two PEC pipes 214a, b; and driving fluid input 244 and output 246 valves being located as a block 230b within, and enclosed by, another two PEC pipes 214c, d. The PEC system 212 has the advantage that each pipe 214a, b, c, d can extend in the same plane without any variations in height (i.e. there is no height difference along the PEC pipe 214).

[0069] Fig. 13 shows a fourth PEC system 312 in which the block valve arrangement 330 is centrally located, and located between two sets of PEC pipes. The first set comprises two PEC pipes 314a, b; and the second set also comprises two PEC pipes 314c, d.

[0070] In use, the PEC system 10 is located near a sea or lake bed (for example, several tens of metres above the sea or lake bed), which is significantly lower in altitude than a final delivery point (e.g. at the surface of the sea) at which slurry is to be delivered. The PEC system 10 may hang freely (via the risers) from a ship (or other vessel) on the sea surface. In this embodiment, the slurry comprises ore particles (also referred to as polymetallic nodules) ranging in size from 10 to 200 mm located in a liquid carrier to produce a slurry of entrained and suspended ore particles.

[0071] In this embodiment, each PEC pipe 14 comprises a thermoplastic composite pipe (TCP); although in other embodiments the pipes may be made from a different material or composite, and the inner surface of the PEC pipe 14 may include a wear resistant or low friction coating. Advantages of using TCP for the PEC pipe 14 include lighter weight than steel or another metal, corrosion and wear resistance, improved flexibility for fabricating bends therein, compared with metals.

[0072] In this embodiment, each PEC pipe 14 is approximately 160m long, but a different pipe length may be used in other embodiments.

[0073] It will now be appreciated that a prior art hydraulic ore hoisting system can be upgraded by replacing the PEC system with PEC system 10.

[0074] It will now be appreciated that a PEC system can be provided that can easily be deployed through a moonpool on a surface vessel on the sea or a lake, with improved balance and geometry.

[0075] Another advantage of the PEC system 10 is its compactness and symmetry, which facilitates ease of handling and transport to and around a mining vessel (e.g. an ocean going ship) and through the vessel's moonpool.

[0076] Another advantage of the PEC system 10 is that all of the valves for one PEC pipe (e.g. 14a) are located in one quadrant of the block valve arrangement 30, which minimises the total height of the PEC system 10.

[0077] The common slurry input manifold enables a reduction in the height of the PECs 12, which reduces the volume of settled solids from the slurry.

[0078] Another advantage of the vertical in-line stacked PEC pipes 14 is that it minimises hydrodynamic drag (which is an object's motion resistance in water) when deploying and retrieving the PEC system 10 into and out of the sea. During operation (towage) the shape of the subsea PEC system 10 behaves substantially like a disc, having low resistance (hydrodynamic drag) as it "cuts" through the sea water. The relatively open structure (perforation) of the PEC system 10 design also minimises drag and provides space for assembly, maintenance, and general accessibility. This includes allowing remote operating vehicles (ROVs) to access many of the key maintenance areas of the PEC system 10.

[0079] The terms "comprising", "including", "incorporating", and "having" are used herein to recite an open-ended list of one or more elements or steps, not a closed list. When such terms are used, those elements or steps recited in the list are not exclusive of other elements or steps that may be added to the list.

[0080] Unless otherwise indicated by the context, the terms "a" and "an" are used herein to denote at least one of the elements, integers, steps, features, operations, or components mentioned thereafter, but do not exclude additional elements, integers, steps, features, operations, or components.

[0081] The presence of broadening words and phrases such as "one or more," "at least," "but not limited to" or other similar phrases in some instances does not mean, and should not be construed as meaning, that the narrower case is intended or required in instances where such broadening phrases are not used.Reference numerals

[0082] Pressure exchange chamber system 10, Pressure exchange chamber 12a, b, c, d, 112, 212, 312 Pressure exchange chamber pipe 14a, b, c, d; 214a, b, c, d; 314a, b, c, d Central frame 16 Central core 18 Lateral support wings 20 Frame extensions (perimeter framework) 22 Upright lattices 24 Hydraulic power unit 26 Slurry feed pump 28 Block valve arrangement 30, 130, 230, 330 Central portion (of block valve arrangement) 32 Slurry input valves 34a, b, c, d Slurry output valves 36a, b, c, d Side portions (of block valve arrangement) 40, 42 Driving fluid (or water) input valves 44a, b, c, d Driving fluid (or water) output valves 46a, b, c, d Compression valves 48a, b, c, d Decompression valves 50a, b, c, d Slurry output pipe coupling 60 Driving fluid riser coupling 62 First driving fluid output pipe 64 Second driving fluid output pipe 66 Slurry input pipe 68 Slurry input manifold 70 Slurry input connecting pipe 72 Angled pipe segments 74a, b, c, d Pulsation dampeners 80 Slurry end of PEC pipe 82 Slurry pipe 84a, b, c, d Driving fluid end of PEC pipe 86 Driving fluid pipe 88a, b, c, d Slurry inflow arrows 90 Slurry outflow arrows 92

Claims

1. A pressure exchange chamber (12, 112, 212) comprising: (i) a pressure exchange chamber pipe (14, 214); (ii) a driving fluid input valve (44) and a driving fluid output valve (46); and (iii) a slurry input valve (34) and a slurry output valve (36), characterised in that (a) the pressure exchange chamber pipe (14, 214) extends around a perimeter, (b) the driving fluid input valve (44) and the driving fluid output valve (46) are both enclosed by the pressure exchange chamber pipe (14, 214), and (c) the slurry input valve (34) and the slurry output valve (36) are both enclosed by the pressure exchange chamber pipe (14, 214).

2. A pressure exchange chamber according to claim 1, wherein the driving fluid valves (44, 46) and the slurry valves (34, 36) are generally centrally located and surrounded by the pressure exchange chamber pipe (14, 214).

3. A pressure exchange chamber according to claim 1 or 2, wherein the pressure exchange chamber pipe (14, 214) is substantially uniformly disposed around the driving fluid valves (44, 46) and / or the slurry valves (34, 36).

4. A pressure exchange chamber according to any preceding claim, wherein the pressure exchange chamber further comprises a driving fluid input pipe (62) and a slurry input pipe (68), both pipes (62, 68) being enclosed by the pressure exchange chamber pipe (14, 214).

5. A pressure exchange chamber according to any preceding claim, wherein the pressure exchange chamber pipe (14, 214) is arranged in a generally horizontal plane.

6. A pressure exchange chamber according to any preceding claim, wherein the pressure exchange chamber further comprises a driving fluid output pipe (88) and a slurry output pipe (84), both pipes (84, 88) being enclosed by the pressure exchange chamber pipe (14, 214).

7. A pressure exchange chamber according to any preceding claim, wherein the pressure exchange chamber pipe (14, 214) comprises a thermoplastic composite pipe.

8. A pressure exchange chamber system comprising: a central frame (16); and a plurality of pressure exchange chambers (12, 112, 212) according any preceding claim, wherein the pressure exchange chamber pipes (14, 214) are arranged in stacked planes around the central frame (16), and each of the plurality of sets of driving fluid input (44) and output (46) valves and slurry input (34) and output (36) valves are associated with a respective pressure exchange chamber pipe (14, 214); and the sets of driving fluid (44, 46) and slurry (34, 36) valves are supported by the central frame (16).

9. A pressure exchange chamber system according to claim 8, wherein the pressure exchange chamber pipes (14, 214) are arranged in generally horizontal planes that are vertically stacked in registration with each other.

10. A pressure exchange chamber system according to claim 8, wherein the driving fluid and slurry input and output pipes are located within the central frame (16) near to a centre of gravity of the pressure exchange chamber system.

11. A pressure exchange chamber system according to claim 10, wherein each driving fluid input and output valve (44, 46) has an associated compression and decompression valve (48, 50), and the compression and decompression valves (48, 50) are located in line with, and at generally the same height as, the associated driving fluid input and output valves (44, 46).

12. A pressure exchange chamber system according to any of claims 8 to 11, further comprising a slurry input manifold (70) comprising an upwardly extending pipe (72) and a plurality of pipe segments (74) extending upwardly and outwardly therefrom, each pipe segment (74) being coupled at an upper end to a respective slurry input valve (34).

13. A pressure exchange chamber system according to any of claims 8 to 12, wherein each pressure exchange chamber pipe defines a generally rectangular shape having bends at each of the four corners.

14. A pressure exchange chamber system according to claim 7, wherein each thermoplastic composite pipe comprises a circular cross-section.

15. A hydraulic ore hoisting system including the pressure exchange chamber system of claims 8 to 14.

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