GB2588953A - A water desalination process - Google Patents
A water desalination process Download PDFInfo
- Publication number
- GB2588953A GB2588953A GB1916663.6A GB201916663A GB2588953A GB 2588953 A GB2588953 A GB 2588953A GB 201916663 A GB201916663 A GB 201916663A GB 2588953 A GB2588953 A GB 2588953A
- Authority
- GB
- United Kingdom
- Prior art keywords
- container
- water
- desalination process
- submerging
- permeate
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 title claims abstract description 156
- 238000010612 desalination reaction Methods 0.000 title claims abstract description 59
- 239000012466 permeate Substances 0.000 claims abstract description 57
- 238000001223 reverse osmosis Methods 0.000 claims abstract description 40
- 239000012528 membrane Substances 0.000 claims abstract description 39
- 238000003306 harvesting Methods 0.000 claims abstract description 21
- 230000003204 osmotic effect Effects 0.000 claims abstract description 7
- 238000005086 pumping Methods 0.000 claims abstract description 4
- 238000000034 method Methods 0.000 claims description 37
- 239000012141 concentrate Substances 0.000 description 6
- 230000007613 environmental effect Effects 0.000 description 5
- 230000008901 benefit Effects 0.000 description 4
- 235000012206 bottled water Nutrition 0.000 description 4
- 239000003651 drinking water Substances 0.000 description 4
- 230000000694 effects Effects 0.000 description 4
- 230000005611 electricity Effects 0.000 description 3
- 238000000605 extraction Methods 0.000 description 3
- 238000009434 installation Methods 0.000 description 3
- 239000000463 material Substances 0.000 description 3
- 150000003839 salts Chemical class 0.000 description 3
- 239000010866 blackwater Substances 0.000 description 2
- 238000004891 communication Methods 0.000 description 2
- 238000010276 construction Methods 0.000 description 2
- 239000000356 contaminant Substances 0.000 description 2
- 238000007667 floating Methods 0.000 description 2
- 238000012423 maintenance Methods 0.000 description 2
- 238000013022 venting Methods 0.000 description 2
- 241000251468 Actinopterygii Species 0.000 description 1
- 239000012267 brine Substances 0.000 description 1
- 230000008878 coupling Effects 0.000 description 1
- 238000010168 coupling process Methods 0.000 description 1
- 238000005859 coupling reaction Methods 0.000 description 1
- 239000002803 fossil fuel Substances 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 239000008239 natural water Substances 0.000 description 1
- 230000001737 promoting effect Effects 0.000 description 1
- 238000000746 purification Methods 0.000 description 1
- HPALAKNZSZLMCH-UHFFFAOYSA-M sodium;chloride;hydrate Chemical compound O.[Na+].[Cl-] HPALAKNZSZLMCH-UHFFFAOYSA-M 0.000 description 1
- 239000003381 stabilizer Substances 0.000 description 1
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D61/00—Processes of separation using semi-permeable membranes, e.g. dialysis, osmosis or ultrafiltration; Apparatus, accessories or auxiliary operations specially adapted therefor
- B01D61/02—Reverse osmosis; Hyperfiltration ; Nanofiltration
- B01D61/08—Apparatus therefor
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D61/00—Processes of separation using semi-permeable membranes, e.g. dialysis, osmosis or ultrafiltration; Apparatus, accessories or auxiliary operations specially adapted therefor
- B01D61/02—Reverse osmosis; Hyperfiltration ; Nanofiltration
- B01D61/10—Accessories; Auxiliary operations
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/44—Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis
- C02F1/441—Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis by reverse osmosis
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2103/00—Nature of the water, waste water, sewage or sludge to be treated
- C02F2103/08—Seawater, e.g. for desalination
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
- Y02A20/00—Water conservation; Efficient water supply; Efficient water use
- Y02A20/124—Water desalination
- Y02A20/131—Reverse-osmosis
Landscapes
- Engineering & Computer Science (AREA)
- Water Supply & Treatment (AREA)
- Chemical & Material Sciences (AREA)
- Nanotechnology (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Life Sciences & Earth Sciences (AREA)
- Hydrology & Water Resources (AREA)
- Environmental & Geological Engineering (AREA)
- Organic Chemistry (AREA)
- Separation Using Semi-Permeable Membranes (AREA)
Abstract
A water desalination process comprises the steps of submerging, in saltwater, a container 3 having a charging inlet 5 covered by a reverse osmosis (RO) membrane 7 to a filling depth where the water pressure external the container adjacent the RO membrane exceeds the osmotic pressure of the RO membrane, preferably wherein the filling depth is at least 270m; filling the container with permeate water and harvesting the permeate water from the interior of the container. The permeate harvesting may involve raising the container from the filling depth such that at least part of the container is above the saltwater surface. In this instance, the permeate can be harvested sequentially from a series of discharge outlets which are spaced apart along the height of the container. Alternatively, the permeate harvesting may involve pumping the water from the submerged container. The submerging can comprise driving the container downwards along a guide assembly 11 comprising a pulley 15, a cable 13 led around the pulley, and a counterweight. The counterweight can be a second container, wherein the pair of containers may be operated in a funicular fashion. The energy requirement for passing the saltwater through the RO membrane is significantly reduced.
Description
"A water desalination process"
Introduction
This invention relates to a water desalination process.
As world population and urbaniSation increase, many cities are beginning to experience severe water shortages. These water shortages are further compounded by drought and other major climatic events. As a result, there has been a rise in the number of desalination plants commissioned to satisfy major cities' water requirements.
Desalination plants can use a reverse osmosis technique to remove salt and other impurities from saltwater to ultimately produce potable water that may be used in the city's water supply. In simple terms, saltwater is forced under high pressure through. a reverse osmosis (RO) membrane resulting in permeate water and concentrate water.
The permeate water may be further treated if necessary to produce potable water and the concentrate water may be subjected to further RO techniques to increase the yield of permeate water harvested from the saltwater and/or the concentrate water may be discharged back out to sea.
Although desalination plants offer a useful source of potable water, there are a number of problems with desalination plants. First of all, the cost of building a desalination plant is prohibitively expensive for all but the wealthiest of countries. Secondly, the-cost of running the desalination plant is also prohibitively expensive as the desalination plants use large amounts of electricity to pump the saltwater through the RO membrane under high pressure. As a result, many third world countries that could benefit from a desalination plant are simply unable to afford the installation and running costs of the desalination plant. Thirdly, there are concerns regarding the environmental impact that desalination plants may have. particularly if fossil fuels are used to satisfy the electricity requirement. There are further environmental concerns surrounding the salinity of the discharged concentrate water and the effects on marine life and fish stocks in the environs of the concentrate water discharge outlet. Fourth, the desalination plant may only be required to operate during times of drought of extreme water shortages and at other times the desalination plant may be effectively redundant. -2 -
It is an object of the present invention to provide a water desalination process that overcomes at least some of these problems and offers a useful alternative to the consumer.
Statements of Invention
According to the invention there is provided a water desalination process comprising the steps of: submerging, in saltwater, a container having a charging inlet and a reverse osmosis (RO) membrane covering the charging inlet, to a filling depth where the water pressure, psv" of the saltwater external' the container adjacent the RO membrane exceeds the osmotic pressure, pa, of the RO membrane; filling the submerged container with permeate water passing through the RO membrane; and harvesting the permeate water from the interior of the container.
There are several advantages to providing the process according to the invention. By having such a process, the energy requirement for passing the saltwater through the RO Membrane will be significantly reduced. Instead of expending large amounts of electricity pumping the saltwater through a RO membrane, the natural water pressure at depth is utilised to good effect to cause water to pass through the RO membrane. This will reduce both the cost and the environmental impact of the process.
Secondly, highly advantageously, the process will be performed "out at sea". This will mean that the process will not require a large land-based desalination plant. As a consequence, there will be no need for the prohibitively expensive capital investment in the plant. In 'addition, the equipment required to carry out the process will effectively be mobile and may be moved from one location to another if and when it is required. In this way, the equipment will not lie idle and be redundant as may be the case if fixed in one location. Furthermore, concerns regarding the environmental impact of increased concentrations of brine are allayed to a degree as the process is being carried out further away from shore where the concentrate water may be diluted more effectively back into the ocean or sea. In addition, the process is being.carried out at depths where there is less marine life and therefore the impact on marine life will be reduced.
In one embodiment of the invention there is provided a water desalination process in which the step of harvesting the permeate water from the interior of the container comprises raising the container from the filling depth for harvesting of the permeate water. In this way, the container may be brought up from the depths in order to empty the container, obviating the need to pump the water from the container at depth.
In one embodiment of the invention there is provided a water desalination process in which the step of harvesting the permeate water from the interior of the container comprises raising the container to a point where at least portion of the container is above the surface of the saltwater. In this way, access to the permeate water inside the container will be facilitated. Furthermore, by operating the process in this way, the container will be more easily accessible for maintenance.
In one embodiment of the invention there is provided a water desalination process in which the process comprises sequentially harvesting the permeate water from a series of discharge outlets disposed spaced apart from each other along the height of the container. In this way, the water may be drained from the container as it rises out of the water. As more permeate water is removed from the interior of the container, the container will rise further, thereby allowing more water to be removed from the interior of the container.
In one embodiMent of the invention there is provided a water desalination process in which the process comprises the step of evacuating the container of air prior to and or during submerging the container. By evacuating air from the container, this will assist in the filling of the container as it will increase the pressure differential across the RO membrane and air pressure that could act against the filling of the container will. not build up inside the container as-it is being filled with permeate water. If desired, the container does not have to be fully evacuated and indeed pressurized air may be kept in the container to assist with harvesting the water from the container. Similarly, by having -4 -some air in the container, this will affect the container buoyancy and may assist in the raising Of the container if necessary.
In one embodiment of the invention there is provided a water desalination process in which the process comprises submerging the container to a depth in which the water pressure, psw, of the saltwater external the container adjacent the RO membrane is greater than of the order of 390psi (26.88Bar). By submerging the container to this depth, a membrane suitable for extracting salt and other materials from the saltwater may be used to good effect.
In one embodiment of the invention there is provided a water desalination process in which the process comprises the step of delivering the harvested permeate water to a tanker for onwards transport. In this way, the water that has been harvested may thereafter be transported ashore to' a suitable distribution network or indeed may be brought to a remote location for further treatment or consumption elsewhere.
In one embodiment of the invention there is provided a water desalination process in which the process comprises the step of delivering the harvested permeate water ashore via a pipe network, wherein one end of the pipe network is located offshore. This is seen as a particularly useful implementation of the present invention. The equipment to carry out the process may be substantially fixed and the permeate. water may be brought ashore via a pipe network. It is envisaged that the equipment may be required permanently in some areas (for example, geographical areas with very low rainfall volumes where desalination plants are required on a permanent basis) in which case the main benefits of locating the equipment to carry out the process offshore and delivering the water onshore using a p'pe network will be reduced energy requirement of the process of harvesting the permeate water and the reduced environmental impact of the process.
Alternatively, the equipment to carry out the process may be substantially mobile and may be connected up to the pipe network only when in use in that location. It is envisaged that certain areas may require their reservoirs or storage supplies to be topped up from time to time in which case, the equipment for carrying out the process may be brought to that location and operated until the supplies have been adequately -5 -replenished. Once replenished; the equipment may be moved on to the next location. Indeed, it is envisaged that a tanker pre-filled with permeate water could use the pipe network to deliver water ashore.
In one embodiment of the invention there is provided a water desalination process in which there is provided a guide assembly for guiding the container during submersion and raising of the container, the guide assembly including an anchor to tether the guide assembly in a substantially vertical orientation in the saltwater. This is seen as a useful way of predictably submerging and raising the container.
In one embodiment of the invention there is provided a water desalination process in which the step of submerging the container comprises driving the container downwards along the guide assembly. By driving the container downwards along the guide assembly, .the container can reach the required depth quicker thereby increasing the amount of water over time that may be harvested from the container. The container may be driven using a propeller on the container or alternatively a cable may be used to pull the container to the required depth. As a further still embodiment, a fixed cable may be provided which may be grasped by a clamp on the container that may be used to advance the container down the cable. If the container is driven by a propeller or other means, a battery may be provided to power the propeller. The battery would preferably be a rechargeable battery that could be charged and thereafter used to submerge the container at night. If the battery is charged using a PV array or the like, the battery could be charged during the day and the container submerged at night.
In one embodiment of the invention there is provided a water desalination process in which the guide assembly comprises, at least one pulley, a cable led around the at least one pulley, and a counterweight.
In one embodiment of the invention there is provided a water desalination process in which the counterweight is a second container and the pair of containers are operated in a funicular fashion.
In one embodiment of the invention there is provided a water desalination process in which the container is substantially cylindrical with the charging inlet covered by the RO membrane being located at or adjacent the base of the container.
In one embodiment of the invention there is provided a water desalination process in which the step of submerging the container comprises submerging the container to a depth of at least 400m.
In one embodiment of the invention there is provided a water desalination process in which the step of submerging the container comprises submerging the container to a depth of between 400m and 700m.
In one embodiment of the invention there is provided a water desalination process in which the step of submerging the container comprises submerging the container to a 15 depth of between 450m and 650m.
In one embodiment of the invention there is proVided a water desalination process in which the step of submerging the container comprises submerging the container to a depth of between 500m and 600m.
In one embodiment of the invention there is provided a water desalination process in which there is provided a compressed air supply and a ballast tank operable in conjunction with the compressed air supply to raise or lower the container. This is seen as an efficient way of allowing the container to be submerged and then raised orce more. In essence, the container can be lowered and raised in a manner similar to a submarine, This may be achieved in a controlled manner. -7 -
Detailed Description of the Invention
The invention will now be more clearly understood from the following description of some embodiments thereof given by way of example only with reference to the accompanying drawings, in which:-Figure 1 is a diagrammatic representation of an apparatus for performing the process according to the invention; Figure 2 is a diagrammatic representation of a container for use in the process according r.o the invention.
Referring to Figure 1, there is shown an apparatus in which the process according to the invention may be performed, indicated generally by the reference numeral 1. The apparatus 1 comprises a submersible container 3, having a charging inlet 5 with a reverse osmosis (RO) membrane 7 covering the charging inlet 5. The apparatus further comprises a platform 9 and a guide assembly 11. The guide assembly 11 in turn comprises a cable 13 led around a pair of pulleys 15, 17 and an anchor 19. One of the pulleys 15 is mounted on the platform while the other of the pulleys 17 is submerged and tethered to the anchor 19. The container is connected to the cable and preferably there is provided means (not shown) to drive the container along the guide assembly 11.
In use, the container 3 is submerged to a filling depth where the water pressure, ps,,, of the saltwater external the container adjacent the RO membrane exceeds the osmotic pressure, pp, of the RO membrane. Once the water pressure exceeds the osmotic pressure, the container will begin to fill with permeate water. Salt and other materials will be trapped on the exterior of the RO membrane. Once the container has been sufficiently filled with permeate water, the permeate water is harvested from the container. In the embodiment shown, the permeate water is harvested by raising the container to the surface once more and emptying the permeate water from the container through a discharge outlet.
Referring now to Figure 2, there is shown a diagrammatic representation of a container that may be used in the process according to the invention, indicated generally by the -8 -reference numeral 30. The container 30 comprises a valve 31 through which air from the interior of the container may be released from the container prior to and or during the submersion of the container as well as prior to and or during the filling of the container with permeate we-2r. By venting the air from the interior of the container, the buoyancy of the container will be reduced thereby promoting the submersion of the container.
Furthermore, if air is vented from the container before and or during filling of *the container with permeate air, the air pressure inside the container will nct build up to a point where it will inhibit filling of the container. Indeed, if a partial vacuum is applied to the interior of the container, this may promote filling of the container. ;The container 30 further comprises a plurality of discharge apertures 33 in communication with the interior of the container, each of which is provided with valve arrangement, indicated by the reference numeral 35, so that the permeate water may be evacuated from the container. The discharge apertures 33 and valves 35 are spaced apart from each other along the height of the container so that as the container 30 rises from being filled and the uppermost tap 35 emerges out from the water, the permeate water may be emptied through this tap 35. As the permeate water empties from tie container and is replaced by air, the container will become lighter and will rise further out of the water, revealing the next tap which may then be connected to a discharge pipe for harvesting the water out of the container. This is repeated until all the permeate waver has been i.emoved from the container. The taps 35 are only shown extending down a portion of the container however this is not intended to be limiting and the taps and discharge apertures may extend lower along the container. ;It will be understood that the apparatus described above is for illustrative purposes only as one example of apparatus that may be used in the performance of the invention and illustrates one way of implementing the invention. The actual apparatus used in the operation of the process may differ significantly in construction and material respects. What is important is that the apparatus is able to perform the process. The kernel of the process invention is the ability to submerge a container with a RO membrane and use the inherent water pressure at depth to fill the container with permeate water through the RO membrane before harvesting the permeate water from the Container. Various additional features, alternatives and modifications will be discussed in mcre detail below. -9 - ;Container: The container 3, 30 is substantially cylindrical in shape and has a charging inlet 5 at the base of the container with a RO membrane covering the charging inlet 5. The RO membrane is effectively "plugging" the charging inlet so that water under pressure may pass though the RO membrane. The container has a vent valve for venting air from the container if necessary and a discharge aperture with a valve and/or a tap for evacuating water from the container. ;If desired, the container may be provided with one or more ballast tanks and a pressurised gas supply, including, if desired, an air compressor and if required, a power supply and control means. In this way, the ballast tank and air supply may be used to submerge and raise the container. The container may also be provided with a means to propel the container through the water, such as, but not limited to, a propeller and a motor. ;The container is shown as cylindrical however this is not necessarily limiting and other shapes will be readily envisaged. Indeed, the cylinder is oriented with its curved side being oriented vertically in the water however this is not intended to be limiting and the curved side could be oriented horizontally or at an angle other than horizontal or vertical in the water. The charging inlet and the RO membrane plugging the charging inlet are at the base of the container however they could be positions along the side or elsewhere around the container and more than one RO membrane and more than one charging inlet in the container are also readily envisaged.. The container is shown used in conjunction with a guide assembly however it is envisaged that this may not be necessary. For example, the container could be a piloted or remotely operated vehicle, similar to a submarine, that could be submerged to a desired depth, filled with permeate water through its RO membrane and thereafter raised to harvest the permeate water. ;Platform: The platform 9 in the embodiment shown in Figure 1 is a floating platform. The floating platform may be provided with one or more anchors or stabilisers to allow the platform hold station in the water. For example, it is envisaged that the platform could take a form similar or identical to an oil rig platform. For example. the Jack-Up Saturn (Registered Trade Mark, ®) produced by Keppel-FELS of Singapore, or the Stena Don ® rig built in the Kvaerner Warnow shipyard in Germany are seen as suitable configurations that could be used for the purpose. Alternatively, the platform may be provided by way of a ship or other vessel equipped to submerge and retrieve, the container. For example, the Stena IceMax ® built by Samsung Heavy Industries is one such vessel that could be adapted to submerge and receive a container. The platform may have storage tanks for the storage of the permeate water, treatment facilities for further treatment of the permeate water to make it potable, and or a connection to a pipe network for delivery of the water back to shore or to a tanker (not shown) for transport. ;It is envisaged that for stability, the rig or the ship used to provide the platform may have a central, substantially vertical aperture through its hull which the container may be submerged and raised through if desired once more. ;Guide Assembly: The guide assembly 11 comprises a cable 13 and a pair of pulleys, 15, 17, one of which is mounted on the platform and the other of which is submerged and tethered to an anchor. In this way, the container may be connected to the cable 13 and the container is lowered and raised along the cable. The container may be fixed in position along the length of the cable and the cable rotated clockwise or anticlockwise around the pulleys to raise or lower the container. In this way, the pulley 15 above surface would be a driving pulley and the pulley 17 that is submerged would be a driven pulley. It is envisaged that only one pulley (on the platform) may be required in certain alternative configurations. In an alternative configuration, instead of providing a pair of pulleys as illustrated that-may be problematic, it is envisaged that two winch pulleys topside and a submerged non-driven pulley submerged below the water could be used to good effect. ;If one or more pulleys are used, a counterweight may be provided to balance the container. Indeed, the counterweight may be another container so that the containers are operated in a manner akin to a funicular railway in that as one container is lowered, the other container is raised and vice versa. ;Alternatively, the cable could be a fixed cable and the container would be provided with either a gripping means to engage the cable and a motor to advance the container downwards and, if desired, upwards along the cable. Alternatively, the cable could be a fixed cable, the container may have a coupling means mounted thereon, such as an annular collar, to surround and engage the cable and hold the container in position relative to the cable. The container could further comprise a motor to drive the container downwards along the cable, using the cable as a guide only. ;Instead of being anchored, the submerged pulley could be connected to a submerged frame. Indeed, it is envisaged that in certain areas, the coastline and the underwater topology would be suited to a track, led from the shore out to sea along the seabed or structure connected to the seabed. In this way, the container or a series of containers connected together like a train, could be lowered along the track to a desired depth, filled, and then raised along the track once they have been filled. ;Water harvesting: In the embodiments described, the container is raised at least partially proUd of the water so that the permeate water may be retrieved from the container. It is envisaged that in other embodiments, the container could be permanently submerged or quasi-permanently submerged (e.g. only resurfaced for maintenance) and a conduit in communication with the interior of the container could be provided to allow permeate water from the interior of the container to be brought to the surface. ;Alternatively, the container could, be raised partially proud of the surface or to a height above filling height but below the surface and an extraction pipe connected to the container tc harvest the water. Water could be evacuated from the container by suction through an extraction pipe or using a pump (submersible or other) or by pumping air into the container and allowing evacuating of the water from inside the container out through an extraction pipe. Relatively low levels of air or pump pressure are required to evacuate the water in this Manner. ;In the embodiment shown, there are a number of water outlets mounted along the height of the container. As the container rises out of the water, the water is extracted sequentially from the outlets from the top downwards. As an alternative arrangement, an outlet pipe could be mounted on the platform and could be inserted into a discharge aperture located at or near the top of the container. As the container rises, the outlet pipe could travel deeper into the container so that it is at least partially submerged in the permeate water inside the container. ;Onward transport of water: Once the permeate water has been harvested froM the container, the permeate water can then be delivered to a cities' water supply by a tanker, or by a pipe network from the platform to a pipe network located ashore. The water can then be directed to a reservoir to fill the reservoir if so desired or if the installation is a permanent installation, to a water distribution network. The permeate water can be treated further on the platform or ashore if preferred prior to distribution to the public.water supply network. If desired, the platform could be located offshore where water is transported into tankers and then distributed to the desired location around the globe. ;General Apparatus features: In the embodiments shown, the container is preferably dimensioned to hold several thousand litres of permeate water at a time. Filling times will vary depending on membrane used, depth, and such factors. For example, the container may be dimensioned to hold up to of the order of 10,000m3 of permeate water at a time. 1 m3 equates to 1.000 litres so 10,000m3 would translate to 10 million litres of permeate water. In order to achieve this, the container may be in excess of a hundred meters tall, up to of the order of 250m tall, and from the order of 0.5m in diameter up to several * meters in diameter. It is envisaged that the container will be capable of withstanding the pressure at a depth of the order of 400m to 700m.
It is envisaged that several containers may be mounted on a platform. It is envisaged that at least two containers would be ideal so that one container may be filling while the other is being emptied. The pulley arrangement may also be such that as one container is driven downwards (or drives downwards) the other container is raised.
-13 -General Process features: While the present invention has been described in terms of a water desalination process, it will be understood that other contaminants can and will be removed from the saltwater as pad of the RO process.
Furthermore, the invention has been described as being performed in saltwater and as a desalination process. What is advantageous about performing the invention as a desalination process offshore is that there is a natural head of water capable of providing sufficient pressure to overcome the osmotic pressure, po, of the RO membrane (amongst a number of advantages). It is conceivable that the process could be utilized as a water purification process on blackwater or other contaminated water source to remove contaminants from that water source for the provision of a potable water supply. What would be required in that instance is a suitable RO membrane and a blackwater or other contaminated water source With sufficient depth to provide enough pressure to overcome the osmotic pressure, po, of the RO membrane.
In this specification the terms "comprise, comprises, comprised and comprising'' and the terms "include, includes, included and including" are all deemed totally interchangeabie and should be afforded the widest possible interpretation.
The invention is not limited to the embodiment hereinbefore described but may be varied in both construction and detail within the scope of the appended claims.
Claims (1)
- Claims: (1) A water desalination process comprising the steps of: (2) (3) (4) 25. (5) (6)submerging, in saltwater, a container having a charging inlet and a reverse Osmosis (RO) membrane covering the charging inlet, to a filling depth where the water pressure, psyv, of the saltwater external the container adjacent the RO membrane exceeds the osmotic pressure. pa, of the RO membrane; filling the submerged container with permeate water passing through the RO membrane: and harvesting the permeate water from the interior of the container.A water desalination process as claimed in claim 1 in which the step of harvesting the permeate water from the interior of the container comprises raising the container from the filling depth for harvesting of the permeate Water.A water desalination process as claimed in claim 2 in which the step of harvesting the permeate water from the interior of the container comprises raising the container to a point where at least portion of the container is above the surface of the saltwater.A water desalination process as claimed in claim 3 in which the process comprises sequentially harvesting the permeate water from a series of discharce outlets disposed spaced apart from each other along the height of the container.A water desalination process as claimed in any preceding claim in which the-process comprises the step of evacuating the container of air prior to and or during submerging the container.A water desalination process as claimed in claim 1 in which the step of harvesting the permeate water from the interior of the container comprises pumping the water from the submerged container.(7) A water desalination process as claimed in any preceding claim in which the process comprises the step of delivering the harvested permeate water to a tanker for onwards transport.(8) A water desalination process as claimed in any preceding claim in which the process comprises the step of delivering the harvested permeate water ashore via a pipe network, wherein one end of the pipe network is located offshore.(9) A water desalination process as claimed in any preceding claim in which there is provided a guide assembly for guiding the container during submersion and raising of the container, the guide assembly including an anchor to tether the guide assembly in a substantially vertical orientation in the saltwater.(10) A water desalination process as claimed in claim 9 in which the step of submerging the container comprises driving the container downwards along the guide assembly.(11) A water desalination process as claimed in claim 9 or 10 in which the guide assembly comprises, at least one pulley, a cable led around the at least one pulley, and a counterweight.(12) A water desalination process as claimed in claim 11 in which the counterweight is a second container and the pair of containers are operated in a funicular fashion. 25 (13) A water desalination process as claimed in any preceding claim in which the container is substantially cylindrical with the charging inlet covered by the RO membrane being located at or adjacent the base of the container.(14) A water desalination process as claimed in any preceding claim in which the process comprises submerging the container to a depth in which the water pressure, ps,,, of the saltwater external the container adjacent the RO membrane is greater than of the order of 390psi (26.88Bar).(15) A water desalination process as claimed in any preceding claim in which the step of submerging the container comprises submerging the container to a depth of at ' least 270m.(16) A water desalination process as claimed in any preceding claim in,which the step of submerging the container comprises submerging the container o a depth of between 270m and 700m.(17) A water desalination process as claimed in any one of claims 1 to 16 in which the step of submerging the container comprises submerging the container to a depth of between 450m and 650m.(18) A water desalination process as claimed in any one of claims 1 to 16 in which the step of submerging the container comprises submerging the container to a depth of between 500m and 600m.(19) A water desalination process as claimed in any preceding claim in which there is provided a compressed air supply and a ballast tank operable in conjunction with the compressed air supply to raise or lower the container
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB1916663.6A GB2588953A (en) | 2019-11-15 | 2019-11-15 | A water desalination process |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB1916663.6A GB2588953A (en) | 2019-11-15 | 2019-11-15 | A water desalination process |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB201916663D0 GB201916663D0 (en) | 2020-01-01 |
| GB2588953A true GB2588953A (en) | 2021-05-19 |
Family
ID=69063227
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB1916663.6A Withdrawn GB2588953A (en) | 2019-11-15 | 2019-11-15 | A water desalination process |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2588953A (en) |
Citations (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3060119A (en) * | 1962-05-16 | 1962-10-23 | Frederick D Carpenter | Sea-well conversion of salt water |
| JPS5570387A (en) * | 1978-11-22 | 1980-05-27 | Yoshiro Hosoyama | Fresh water obtaining system by reverse osmosis |
| FR2484391A1 (en) * | 1980-06-12 | 1981-12-18 | Lopez Fernand | Desalination of sea-water by reverse osmosis under hydrostatic pressur - via membrane into vessel submerged at more than 300 m in sea-water |
| US5229005A (en) * | 1991-02-04 | 1993-07-20 | Fok Yu Si | Ocean depth reverse osmosis fresh water factory |
| ES2112206A1 (en) * | 1996-01-26 | 1998-03-16 | Guzman Martinez Valls Gines | System with fixed or movable support for desalinating sea water with reverse osmosis cell device, immersed at variable working depths |
| DE10211788A1 (en) * | 2002-03-16 | 2003-10-02 | Mielke Sabine | Seawater reverse osmosis desalination process involves use of assembly raising and lowering closed loop pipe of deep sea modules and collector tanks |
| US20090236286A1 (en) * | 2009-06-09 | 2009-09-24 | Salyer Ival O | Method, apparatus, and processes for producing potable water utilizing reverse osmosis at ocean depth in combination with shipboard moisture dehumidification |
| US20090250398A1 (en) * | 2008-04-07 | 2009-10-08 | Moshe Meller | Seawater desalination system and method |
-
2019
- 2019-11-15 GB GB1916663.6A patent/GB2588953A/en not_active Withdrawn
Patent Citations (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3060119A (en) * | 1962-05-16 | 1962-10-23 | Frederick D Carpenter | Sea-well conversion of salt water |
| JPS5570387A (en) * | 1978-11-22 | 1980-05-27 | Yoshiro Hosoyama | Fresh water obtaining system by reverse osmosis |
| FR2484391A1 (en) * | 1980-06-12 | 1981-12-18 | Lopez Fernand | Desalination of sea-water by reverse osmosis under hydrostatic pressur - via membrane into vessel submerged at more than 300 m in sea-water |
| US5229005A (en) * | 1991-02-04 | 1993-07-20 | Fok Yu Si | Ocean depth reverse osmosis fresh water factory |
| ES2112206A1 (en) * | 1996-01-26 | 1998-03-16 | Guzman Martinez Valls Gines | System with fixed or movable support for desalinating sea water with reverse osmosis cell device, immersed at variable working depths |
| DE10211788A1 (en) * | 2002-03-16 | 2003-10-02 | Mielke Sabine | Seawater reverse osmosis desalination process involves use of assembly raising and lowering closed loop pipe of deep sea modules and collector tanks |
| US20090250398A1 (en) * | 2008-04-07 | 2009-10-08 | Moshe Meller | Seawater desalination system and method |
| US20090236286A1 (en) * | 2009-06-09 | 2009-09-24 | Salyer Ival O | Method, apparatus, and processes for producing potable water utilizing reverse osmosis at ocean depth in combination with shipboard moisture dehumidification |
Also Published As
| Publication number | Publication date |
|---|---|
| GB201916663D0 (en) | 2020-01-01 |
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| Date | Code | Title | Description |
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| WAP | Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1) |