GB2478744A

GB2478744A - De-stratification using venturi pump array

Info

Publication number: GB2478744A
Application number: GB1004348A
Authority: GB
Inventors: Peter Miles Roberts
Original assignee: Verderg Ltd
Current assignee: Verderg Ltd
Priority date: 2010-03-16
Filing date: 2010-03-16
Publication date: 2011-09-21
Also published as: GB201004348D0; WO2011114157A3; WO2011114157A2

Abstract

Water is pumped between depths in a body of water e.g. ocean, to reduce the surface temperature and / or to redistribute carbon dioxide from relatively shallow to relatively deep water, to increase the rate of absorption from the atmosphere. The pump system comprises a series of modules, each having an array of pipes 12 in a spaced side by side arrangement. A venturi is defined between adjacent pipes, and the pipes have a series of outlet holes 22 along their length, so that current flow across the module draws water through the pipes. Inlet holes 24 are positioned at a different depth so that water is drawn from a first depth 34 to a second depth 36. A further module may move water in the opposite direction (see figure 3).

Description

System for Ocean Mixing

Technical field

[0001] This invention relates to a system for mixing water in a current moving through a body of water. In particular the invention relates to a system for mixing water found at different depths in an ocean current having different concentrations of carbon dioxide and/or different temperatures.

Background art

[0002] The world's oceans act as a "carbon sink" by absorbing atmospheric carbon dioxide, however as the carbon dioxide concentration in the surface layer of water in the ocean increases, the ability of the oceans to absorb atmospheric carbon dioxide decreases.

[0003] Systems have been described to increase the amount of carbon dioxide sequestered in the world's oceans. However these methods generally rely on the sequestering the carbon dioxide in the seabeds or pumping gaseous or precooled carbon dioxide into deep levels of the ocean. Other methods considered for sequestering carbon dioxide in the ocean have comprised fertilizing an area of ocean to increase plant life in the ocean to sequester carbon dioxide. However many of these methods are energy intensive.

[0004] The absorption of carbon dioxide into the ocean only occurs initially into the surface layer, i.e. the top 400m or so of water depth, where turbulent mixing from wave action occurs. It is thought to take at least 1000 years or more for any change in the carbon dioxide concentration of the top 400m to reach equilibrium with the carbon dioxide level of water below this thin surface layer.

[0005] Therefore it is an object the invention to provide a system for pumping the surface layer of water down into the body of deeper ocean water.

Disclosure of the invention

[0006] This invention provides a system for moving water between depths in a body of water, comprising: a series of modules, each module formed from an array of pipes in a spaced side by side arrangement having a series of outlets along the length of the pipe, such that a venturi is defined between the walls of adjacent pipes; a flow conduit having an inlet and connected to the pipes; wherein, in use, the inlet is positioned on the flow conduit at a first depth and the outlets are located on the pipes at a second depth; and water from the body can enter the flow conduit via the inlet and the pipes are connected to the flow conduit such that the flow of water between the pipes causes a venturi pump effect drawing water through the flow conduit and inducing a current flow in the pipes to transfer water through the pipes from the first depth to the second depth.

[0007] In one module the first depth can be lower than the second depth. In another module the first depth is higher than the second depth.

[0008] The system can comprise a turbine located in the flow conduit, such that water flowing through the conduit drives the turbine. A generator can be connected to the turbine.

[0009] The pipes can comprise a flow passage, an upstream side and a downstream side; the downstream side tapering away from the flow passage and the pipes are arranged side by side such that opposing walls of adjacent pipes define a venturi section and a first diffuser section extending downstream from the venturi section.

[0010] In one embodiment the profile of the upstream side and the profile of the downstream side are substantially different.

[0011] In another embodiment the upstream end of the pipe extends and tapers away from the outlets such that when the pipes are arranged side by side opposing walls of adjacent pipes define a second diffuser section extending upstream from the venturi section. The profile of the upstream side and the profile of the downstream end can be substantially the same. Profiles of the pipes include hexagonal and elliptical shapes.

[0012] The downstream side can include a buoyancy section.

[0013] The system can comprise at least one module where the inlets are at a shallower depth than the outlets, such that water is transferred from a shallower depth to a deeper depth; and at least one module where the inlets are at a deeper depth than the outlets, such that water is transferred from a deeper depth to a shallower depth.

[0014] The system can comprise a second series of modules located below the first series of modules; wherein the pipes and flow conduits are configured in the second series of modules to transfer water from a shallower depth to a deeper depth and wherein the pipes and flow conduits are configured in the first module to transfer water from a deeper depth to a shallower depth.

[0015] The first series of modules can be integrated with the second series of modules.

[0016] The first series of modules can be connected to the second series of modules such that the inlets on the second module face a direction 180° from the inlets of the first module.

[0017] A second aspect of the invention provides a method for reducing the carbon dioxide content in an area of water comprising using a system as described above to transfer water between a first depth to a second depth; wherein the carbon dioxide content of the water at the first depth is lower than the carbon dioxide content of the water at the second depth.

[0018] The second depth comprises the surface layer of water.

[0019] A method can comprise locating the system across a current in an ocean.

[0020] The method can comprise locating the system such that the modules extend from the bottom of the current to the surface.

[0021] A third aspect of the invention comprises a method for reducing the temperature in an area of water comprising using a system as describe above to transfer water between a first depth and a second depth, wherein the temperature of the water at the first depth is lower than the temperature of the water at the second depth.

[0022] The second depth can comprise the surface layer of water.

Brief description of the drawings

[0023] Figure 1 shows a schematic view of part of a module across a current that spans two zones of water; Figure 2 shows a schematic side view of a SMEC module for transferring water from to the surface from a lower depth in the ocean; Figure 3 shows a schematic side view of a SMEC module for transferring water from the surface to a lower depth in the ocean; Figures 4 -12 show schematic profiles of pipes for use in the modules according to the invention; Figures 13 and 14 shows a general view of one module according to the invention; Figures 15 and 16 shows a general view of a module according to the invention; Figure 17 shows a bird's eye view of one embodiment of the invention Figure 18 shows a schematic part cut away view of one embodiment of the invention through line A-A of Figure 17; Figure 19 a schematic view of the embodiment of the invention through line C-C of Figure 17 Figure 20 shows a schematic part cut away view of one embodiment comprising different modules according to the invention; Figures 21, 22 and 23 show a general view of a module being positioned in the water; and Figure 24 shows a general view of a series of modules in operation.

Mode(s) for carrying out the invention [0024] The basic principle of the invention is to mix the surface layer water with water from deep in the ocean by moving water from the surface layer to a deeper depth in the ocean and vice versa. This will reduce the carbon dioxide in the surface layer of the ocean, thereby allowing the rate of absorption of atmospheric carbon dioxide into the surface layer to increase.

[0025] Figure 1 shows part of a module 10 comprising a series of pipes 12 set across the ocean 14. The pipes extend through at least two regions of the body of water. A first region 16 in the surface water zone has a relatively high carbon dioxide concentration and a second region 18 has a relatively low carbon dioxide concentration. The basic structure of the module 10 comprises a series of the pipes 12 connected to a flow conduit 20. The pipes have outlets 22 for releasing water back into the ocean and the flow conduit has inlets 24 for receiving water from the ocean. A turbine connected to a generator can optionally be located in the flow conduit for generating electricity when the turbine is driven by the flow of water past the turbine.

[0026] Water from the ocean can enter the flow conduit 20 via the inlets 24 and the pipes are connected to the flow conduit such that a primary flow 30 of water between the arrangement of pipes 12 causes a venturi pump effect inducing a flow 32 from inside of the pipes out through the outlets 22 so as to draw water through the flow conduit 20 and drive the turbine if present. A pressure head drop from the upstream water to the intra tube water at the same elevation is caused by the venturi effect; as the current flows through the venturi between the pipes an amplified head loss occurs in the venturi. This induces the secondary flow 32 out through the outlets 22 and induces a high velocity secondary flow through the pipes.

[0027] As shown in Figure 2, water can enter the flow conduit via the inlets at a first deeper depth range. The primary flow 30 of water flowing through the arrangement of pipes 12 forming the array causes the pipes to act as venturi pumps inducing a secondary flow 32 from inside the of the pipes out through the outlets 22 located at the top of the pipes 12 SO as to draw water through the flow conduit via the inlets 24 located at the first deeper depth range. The secondary flow 32 of water flows enters the flow conduit 20 at the first deeper depth range and flows up through the pipes 12 to be released back into the ocean via outlets 22 located at a second shallower depth range. This flow circuit moves water from a deep depth in the ocean to a shallower depth in the ocean, closer to the surface. The module is positioned in the ocean such that the outlets will be positioned such that the water is released into an region of ocean having a different concentration of carbon dioxide than from the region of ocean where the water entered the tubes, i.e. the water moves from a low 002 concentration zone 34 to a high 002 concentration zone 36.

[0028] As shown in Figure 3 to move water from a shallower depth to a deeper depth a primary flow of water flows through the gaps between the pipes forming the modules. The primary flow 30 past the pipes induces a secondary flow 32 of water from a shallow region of the ocean into inlets 24 located in the top section of the flow conduit 20. The secondary flow 32 of water enters the flow conduit at a first shallower depth and flows through the pipe to be released back in to the ocean via outlets 22 located on the pipes at a second deeper depth of the ocean. In this way water is moved from high concentration 002 zone 36 to a low concentration 002 zone 34.

[0029] By replacing the high carbon dioxide containing water at the surface with the low carbon dioxide containing water from below the interface between the high and low 002 zones lying at a depth of for example, 400m, creates a reduction of carbon dioxide levels at the surface and an imbalance between the carbon dioxide concentrations between the ocean and the atmosphere. The surface layer of the ocean can then absorb more carbon dioxide from the atmosphere thereby reducing the atmospheric concentration to a more desirable level.

[0030] Reducing the carbon dioxide concentration can also benefit the sealife, such as crustaceans and coral, which inhabits the surface layer of the oceans. The decrease in carbon dioxide will result in a decrease in acidity of this zone of water.

[0031] In a further embodiment of the invention, the system is used to transfer water from a low temperature zone to a high temperature zone. The modules can be positioned in the ocean to span a high and low temperature zone. Water from the high temperature nearer the surface is transferred to a deeper cooler zone via the tubes of the module. While water from the deeper cooler zone in the ocean is transferred via the tubes of the module to the surface water of the ocean. By replacing the warmer surface water with the cooler water from the deeper section will help cool the surface water temperature, which will help cool the atmosphere and provide better gas absorption.

[0032] In one embodiment the modules comprises feature as described in co-pending GB application 1004321.4 entitled Apparatus for generating power from fluid flow' filed 16 March 2010 in the name of VerdErg Ltd, which is incorporated herein by reference.

[0033] As currents predominately flow in one direction unidirectional modules can be used. This simplifies the structure of the modules. Examples of profile shapes for pipes for use in unidirectional modules are shown in Figures 4-10.

[0034] Each module can comprise an array of pipes 40 having a tapered downstream side 42. Each pipe forming the array can comprises upstream side 44 and a tapered downstream side 42 with a flow passage 46 positioned between the sides. A series of holes or slots 48 are formed along the side of the flow passage 46 near the venturi 50. Adjacent pipes 40 are positioned such a venturi section 50 and a diffuser section 52 is formed between the walls of adjacent pipes 40. Bracing and/or struts 52 can be provided to help strengthen the pipes.

In some embodiments the downstream side 42 can be closed off from the upstream side 44 and flow passage 46 and include a buoyancy section 54.

[0035] The number, shape and arrangement of holes defined along the length of the flow passage can vary. The term holes can include apertures, slots, continuous slots, elongate holes and any other suitable opening into the flow passage.

[0036] In operation the primary flow 56 accelerates into the venturi section 50 between the pipes 40 and flows through the venturi section 50 and decelerates out of the venturi between the walls of the pipes that define the diffuser section 52. As the pressure outside the holes 48 is reduced this induces a secondary flow 58 of water from the pipes 40 out through the holes 48.

[0037] In situations where there is a counter current, e.g. the Arctic Return Current under the Gulf Stream a second module can be interconnected with the first, the second module can be positioned beneath the first module and face the opposite direction.

[0038] In another embodiment bidirectional modules can be used having pipes with symmetrically shaped profiles. Examples of pipes suitable for use in bidirectional flows are shown in Figures 11 and 12.

[0039] Pipes 60 for use in bidirectional flow 70 have a tapered elongate downstream side 62 and a tapered elongate upstream side 64, such that two diffuser sections 66a, 66b are defined between opposing walls of adjacent pipes separated by a venturi section 68. Symmetrical shapes, such as elliptical and hexagonal cross sectional shapes, allow the entrance throat of the venturi to become the diffuser section 66b when the direction of flow 70a is reversed 70b.

[0040] In the embodiment of Figure 13 and 14 the module 80 is for transferring water from a relatively low carbon dioxide region to a relatively high carbon dioxide region. The module 80 comprises an array of vertical pipes 82 having a tapered downstream side 84 and having a flow passage and holes positioned along its length. The pipes are connected to a common horizontal manifold 86 which in turn is connected to a flow conduit 88. The flow conduit 88 has inlets 90 at its lower end for receiving water from deep in the ocean. The flow conduit 80 can comprise turbines which power generators located in a housing 92 above the water, when water flows through the conduit 88 and drives the turbine.

[0041] The embodiment shown in Figures 15 and 16 is a module 100 for transferring water from a relatively high carbon dioxide region to a relatively low carbon dioxide region. The module 100 comprises an array of vertical pipes 102 having a tapered downstream side 104 and having a flow passage and holes positioned along its length. The pipes 102 are connected to a common horizontal manifold 106 which in turn is connected to a flow conduit 108. The flow conduit 108 has inlets 110 at its upper end for receiving water from near the surface of the ocean. The flow conduit can comprise turbines which power a generator located in a housing 112 above the water, when water flows through the flow conduit 108 and drives the turbine.

[0042] Figures 17, 18 and 19 show series of modules of the system for transferring water between different depths. In this case, there are two different types of modules 120, 122. Two modules 120 are for receiving water from a shallower region 124 of the ocean and flank a module 122 for receiving water from a deeper region 126 of the ocean. Each module 120,122 comprises an array of pipes 128 that are arranged substantially vertically and are connected to a flow conduit 130 via horizontal manifolds 132. The flow conduits 130 of the first and third modules 120 comprise inlets 134 at their upper end and a turbine 136 located within the flow conduit 130. The flow conduit 130 of the second module 122 comprises inlets 134 at its lower end. Each flow conduit 130 may comprise a number of turbines 136 connected to a generator via a drive shaft. Each pipe 128 comprises a flow passage 138 and a series of holes 140 along its length.

The tapered downstream side 142 of the pipes is isolated from the flow passage 138 and forms a buoyancy section 144 that can be flooded with water to help maintain the modules in an upright position. A deck structure 146 can extends across the modules 120, 122 and housing 148 for the generator can be located on the top of the modules.

[0043] Figure 20 shows a further arrangement for a series of module for transferring water between different depths. In this case, the flow conduits 130 of the first and third modules 122 comprise inlets 132 at their lower ends while the flow conduit 130 of the second module 120 comprises inlets 134 at its upper end.

Each flow conduit comprises at least one turbine 136. The array of pipes 128 are arranged substantially vertically and are connected to the flow conduit 130 via horizontal manifolds 132. Each pipe 128 comprises a flow passage 138 and a series of holes 140 along its length to release water back into the ocean. The tapered downstream side 142 of the pipes is isolated from the flow passage 138 and forms a buoyancy section 144 that can be flooded with water to help maintain the modules in an upright position.

[0044] Figures 21, 22 and 23 show cross sections of a section of the structure being installed. A module 160 is towed to the position the structure is to be installed by a first tug 162 which holds the module in place against the current 164. A second tug 166 attaches a mooring line 168 extending from the module to an anchor 170. The second tug can then initiate controlled flooding of a buoyancy section 172 of the module. The second tug will lower the anchor to the sea bed 174 as the buoyancy section 172 is flooded. As the buoyancy section is flooded the module will move from a horizontal position to a vertical position, with the first tug 162 controlling the positioning of the module into the correct place. The level of water in the buoyancy section can be controlled to control the position of the module in the water. The first tug can deploy a remotely operated vehicle 176 from a tow line. The ROV can make adjustments to the anchor lines and help join the SMEC section to the main part of the structure previously installed.

The first tug 162 can then disconnect the tow line and retrieve the ROV before leaving the site. The structure is installed to span the vertical depth of the current, or to the sea bed if appropriate. The length of the modules will depend on the depth of the current and may extend down to depths of over I 000m below sea level.

[0045] Additional modules are connected to span the entire width of the current. The number of modules connected to form the structure will depend on the location, however it is preferred that the width of the system will be sufficient to minimise by-pass flow. Decking to help provide access to the modules and buildings can be constructed along the top of the modules.

[0046] The system can comprise a mixture of modules including modules 180 that transfer water from the surface region 182 to deeper region 184 in the ocean, connected to modules 190 that transfer water from deep regions 184 in the ocean to the surface region 182, as shown in Figure 24. Different modules types may be stacked on top of each other having a first higher module having inlets facing a first direction and a lower module having inlets facing a second direction. The second direction can be 180° from the first direction. This is particular suitable where there is a counter current present, with one current under another current flowing in opposite directions. Alternatively the system may comprise modules only of one type.

[0047] While one method of installing a module is described, the method of installation can vary depending on the type of module being installed and the location.

[0048] Where the system is installed in high traffic shipping zones the modules can be installed such that they are submerged deep enough in the water for shipping to pass above.

[0049] While the modules is exemplified with a turbine located in the vertical tubes, where the modules are installed to move water between depths and are not also required to generate electricity it is not necessarily that the turbine is present. However where the system is also used to generate electricity the turbines can be present.

[0050] While the invention is exemplified with a specific embodiment of module, other constructions which transfer water from one depth in a body of water to another depth can also be used, such as that described in W02008/01 5047 or that described in GB0816942.7. Both these applications described modules which can transfer water from a deeper depth in a body of water to a shallower depth.

[0051] While the invention is described with reference to mixing layers of water found in oceans, the invention can be used in other bodies of water having current flows, such as seas etc, where differences in carbon dioxide concentration may exist at different water depths.

[0052] Other changes can be made within the scope of the invention.

Claims

Claims 1. A system for moving water between depths in a body of water, comprising: a series of modules, each module formed from an array of pipes in a spaced side by side arrangement having a series of outlets along the length of the pipe, such that a venturi is defined between the walls of adjacent pipes; and a flow conduit having an inlet and connected to the pipes; wherein, in use, the inlet is positioned on the flow conduit at a first depth and the outlets are located on the pipes at a second depth, and water from the body can enter the flow conduit via the inlet and the pipes are connected to the flow conduit such that the flow of water between the pipes causes a venturi pump effect drawing water through the flow conduit and inducing a current flow in the pipes to transfer water through the pipes from the first depth to the second depth.
2. A system according to claim I wherein the first depth is lower than the second depth.
3. A system according to claim I wherein the first depth is higher than the second depth.
4. A system according to any preceding claim comprising a turbine located in the flow conduit, such that water flowing through flow conduit drives the turbine.
5. A system according to claim 4 comprising a generator connected to the turbine.
6. A system according to any preceding claim wherein the pipes comprises a flow passage, an upstream side and a downstream side; the downstream side tapering away from the flow passage and the pipes are arranged side by side such that opposing walls of adjacent pipes define a venturi section and a first diffuser section extending downstream from the venturi section.
7. A system according to claim 6 wherein the profile of the upstream side and the downstream side are different.
8. An apparatus according to claim 6 wherein the upstream side of the pipe extends and tapers away from the outlets such that when the pipes are arranged side by side opposing walls of adjacent pipes define a second diffuser section extending upstream from the venturi section.
9. An apparatus according to claim 8 wherein the profile of the upstream side and the profile of the downstream side are substantially the same shape.
10. An apparatus according to claim 9 wherein the profile of the pipes is hexagonal.
11. An apparatus according to claim 9 wherein the profile of the pipes is elliptical.
12. An apparatus according to any of claims 6 to 11 wherein the downstream side includes a buoyancy section.
13. A system according to any preceding claim comprising at least one module wherein the inlets are at a shallower depth than the outlets, such that water is transferred from a shallower depth to a deeper depth; and at least one module wherein the inlets are at a deeper depth than the outlets, such that in use water is transferred from a deeper depth to a shallower depth.
14. A system according to any preceding claim further comprising a second series of modules located below the first series of modules; and wherein the pipes and flow conduits are configured in the second series of modules to transfer water from a deeper depth to a shallow depth and wherein the pipes and flow conduit are configured in the first module to transfer water from a shallower depth to a deeper depth.
15. A system according to claim 14 wherein first series of modules is integrated with the second series of modules.
16. A system according to claim 14 or claim 15 wherein the first series of modules are connected to the second series of modules such that the inlets on the second module face a direction 180° from the inlets of the first modules.
17. A method for reducing the carbon dioxide content in an area of water comprising using a system as claimed in any of the preceding claims to transfer water between a first depth to a second depth; wherein the carbon dioxide content of the water at the first depth is lower than the carbon dioxide content of the water at the second depth.
18. A method according to claim 17 wherein the second depth comprises the surface layer of water.
19. A method according to any of claims 17 or 18 comprising locating the system across a current in an ocean.
20. A method according to claims 17, 18 or 19 comprising locating the system such that the modules extend from the bottom of the current to the surface.
21. A method for reducing the temperature in an area of water comprising using a system as describe in any of claims to I to 16 to transfer water between a first depth and a second depth, wherein the temperature of the water at the first depth is lower than the temperature of the water at the second depth.
22. A method as claimed in claim 21 wherein the second depth comprises the surface layer of water.