WO2021028701A2

WO2021028701A2 - System and method for power generation and desalination

Info

Publication number: WO2021028701A2
Application number: PCT/GB2020/051954
Authority: WO
Inventors: Hanwen ZHENG; Wenjing Zhang
Original assignee: Infinities Global Limited
Priority date: 2019-08-15
Filing date: 2020-08-14
Publication date: 2021-02-18
Also published as: WO2021028701A3; CN110498523A

Abstract

There is provided a system for desalinating water, comprising: an energy collection module configured to collect energy from movement of water; and a desalination module configured to desalinate water; wherein water is transferred from the energy collection module to the desalination module using the collected energy.

Description

System and method for power generation and desalination Technical field

[0001] The present disclosure relates to desalinating water and generating power, in particular using energy collected from movement of water. The disclosure is particularly, but not exclusively, applicable to desalinating seawater and collecting tidal energy. The present invention also relates to a combined power generation and seawater desalination system, and to a self-cleaning filter.

Background art

[0002] All existing marine current power generation systems and solar power generation systems are independent, and due to their respective limitations, are unable to achieve energy complementarity. Moreover, in existing marine current power generation systems using seawater as a medium, when seawater is drawn as a medium onto land, there is no seawater desalination, and energy utilization is not maximized.

Summary of the invention

[0003] Aspects and embodiments of the present invention are set out in the appended claims. These and other aspects and embodiments of the invention are also described herein.

[0004] In an aspect of the invention, there is provided a system for desalinating water, comprising: an energy collection module configured to collect energy from movement of water; and a desalination module configured to desalinate water; wherein water is transferred from the energy collection module to the desalination module using the collected energy. In otherwords, the desalination may be powered directly by the energy collection module. Locally collected energy at the energy collection module may be used to force water to the desalination module. This may allow for a more efficient desalination system, since there is no need to separately power the desalination (e.g. by using electricity to pump the water for desalination).

[0005] The desalination module may be passive. That is, the desalination module may not receive a separate power input. The desalination module may comprise a semipermeable membrane configured to receive (high pressure) water; preferably wherein the semipermeable membrane is a reverse osmosis membrane. The desalination module may be positioned on land, preferably above sea level. Wastewater from desalination may be recycled. Water may be transferred to the desalination module at a sufficiently high pressure and/or potential energy for subsequent desalination via the semipermeable membrane. [0006] The system may further comprise a distribution module configured to receive water from the energy collection module; preferably being configured to distribute water to the desalination module. The distribution module may be configured to control water pressure at an inlet to the desalination module. [0007] The system may further comprise a power generation module for generating electricity from movement of water; wherein the distribution module may be in fluid communication with the desalination module and power generation module.

[0008] In another aspect of the invention, there is provided a system for desalinating water and generating power, comprising: a distribution module configured to receive water; a desalination module configured to desalinate water; and a power generation module for generating electricity from movement of water; wherein the distribution module is in fluid communication with the desalination module and power generation module. In otherwords, the power generation module and desalination module are connected in parallel. This may provide a more useful system which can make use of received water differently according to requirements (either for desalination, generating power, or both). [0009] The system may be capable of transferring water selectively from the distribution module to either of the desalination module and power generation module. The system may be capable of transferring water selectively from the distribution module to both of the desalination module and power generation module.

[0010] The distribution module may be configured to control the water pressure at respective inlets of the desalination module and the power generation module. The distribution module may be configured to provide water to the desalination module and to the power generation module at different water pressures and/or different flow rates. The distribution module may comprise a pressure reducing valve in this regard. The distribution module may comprise valves for controlling water flow. Specifically, at least one of a check valve, overflow valve, flow distribution valve, and pressure relief valve may be provided. The power generation module may comprise a water motor; and a generator powered by the water motor.

[0011] The system may further comprise an energy collection module configured to collect energy from movement of water; wherein water is transferred from the energy collection module to the distribution module using the collected energy. Water may then be transferred on to the desalination module and/or the power generation module. The energy collection module may be used to pump the water to the desalination module and/or power generation module, preferably wherein the energy collection module is the only pump upstream of the desalination module and/or power generation module. Water may be used as the medium for energy transfer.

[0012] The energy collection module may comprise a pump for pumping water to the desalination module; the pump being powered by the collected energy. The energy collection module may comprise a turbine for collecting energy from the movement of water; wherein the pump is driven directly by the turbine. The energy collection module may comprise a submerged foundation pile on which the turbine is mounted. Preferably, the energy collection module is submerged at least 10 m below sea level. The system may comprise a plurality of energy collection modules. A plurality of pipelines connecting the energy collection modules to the desalination module and/or the power generation module may be provided. Optionally, a plurality of pipes for conveying water from the plurality of energy collection modules to the desalination module and/or the power generation module is provided. The system may further comprise means for preventing backflow in transferring water to the desalination module and/or the power generation module. The plurality of pipes may comprise a main pipe connecting to the distribution module; and a plurality of secondary pipes connecting the main pipe and the plurality of energy collection modules.

[0013] The system may further comprise a solar heating module configured to collect solar energy and to heat water; wherein water is transferred from the energy collection module to the solar heating module using the energy collected by the energy collection module. Optionally, the energy collection module may comprise means for controlling the distribution of water between the distribution module and the solar heating module.

[0014] In another aspect of the invention, there is provided a system for collecting energy, comprising: an energy collection module configured to collect energy from movement of water; and a solar heating module configured to collect solar energy and to heat water; wherein water is transferred from the energy collection module to the solar heating module using the energy collected by the energy collection module. It will be appreciated that the heated water may be used for purposes other than power generation, e.g. heating. The solar heating module may comprise a solar collector configured to convert solar energy to thermal energy; and means for storing and/or conveying water configured to transfer thermal energy from the solar collector to the stored and/or conveyed water. The solar collector may be a plate solar collector. The solar collector may be arranged at a height above the surface of the sea.

[0015] The system may further comprise a (further) power generation module for generating electricity from energy stored in water; the (further) power generation module being connected to the solar heating module. This may provide a more efficient system, in that water is pumped directly by the energy collection module to the (further) power generation module on shore. Water may be transferred from the energy collection module to the (further) power generation module via the solar heating module using the energy collected by the energy collection module. The (further) power generation module may be configured to generate electricity from the thermal energy of the water received from the solar heating module. The (further) power generation module operates in a closed-loop cycle; preferably wherein the (further) power generation module comprises: a heat exchanger configured to extract the thermal energy and to heat a medium; a turbine running on the medium; a generator powered by the turbine; a condenser for condensing the medium; and a pump for conveying the medium from the condenser to the heat exchanger. The medium is preferably heated water or steam.

[0016] The (further) power generation module may comprise a pump powered by the flow of wastewater from the desalination module; preferably wherein the system further comprises a water motor configured to run on wastewater from the desalination module (i.e. brine) to power the pump. This may improve efficiency as compared to the conventional method of using some of the turbine work in a closed loop cycle to drive the pump. The (further) power generation module may comprise a condenser configured to receive wastewater from the power generation module; preferably wherein said wastewater is used as a coolant. The (further) power generation module may be positioned on land, preferably above sea level. The solar heating module may be positioned at sea; preferably generally above the energy collection module.

[0017] The energy collection module may comprise a self-cleaning device for filtering water, the device being configured to filter impurities from water prior to the water being transferred from the energy collection module. This may improve efficiency, in that water for desalination is filtered at the point of collection rather than at the point of desalination, meaning that energy is not spent on pumping impurities to the point of desalination.

[0018] The water used in the system may be sea water; preferably wherein the energy collection module collects energy from the tidal movement of the water. [0019] According to another aspect of the invention, there is provided a self cleaning device for filtering water, comprising: a filter; and a valve configured to open in response to a drop in differential pressure across the filter thereby to allow fluid to flow onto the filter for cleaning.

[0020] The device may further comprise a head for outputting fluid from the valve. The head may comprise a plurality of apertures, such that fluid is outputted from the head as a plurality of jets. The head may be configured to rotate in use. The head may comprise a further aperture arranged generally perpendicular to the plurality of apertures, such that the jet output via the further aperture causes the head to rotate in use. [0021] The device may further comprise a chamber holding the filter; and a piston used to control the valve. The piston may move in response to a drop in differential pressure thereby to open the valve. The device may further comprise a pressurized chamber used to control the valve, optionally in combination with the piston.

[0022] The device may be at least partially submerged such that surrounding water acts as the cleaning fluid. The water may be provided to the filter at a pressure of at least 200 kPa. The device may be positioned between a pump suction port and a pump outlet.

[0023] According to another aspect of the invention, there is provided a system as described herein, including the device as described herein.

[0024] According to another aspect of the invention, there is provided a method for desalinating water, comprising: collecting energy from movement of water, preferably using an energy collection module; transferring water using the collected energy, preferably from the energy collection module to a desalination module; and desalinating the transferred water; preferably using the desalination module.

[0025] According to another aspect of the invention, there is provided a method for desalinating water and generating power, comprising: receiving water; transferring the water selectively to either or both of a desalination module and a power generation module; using the desalination module, desalinating the water; and using the power generation module, generating power from the movement of water.

[0026] According to another aspect of the invention, there is provided a method for collecting energy, comprising: collecting energy from movement of water, preferably using an energy collection module; transferring water using the collected energy, preferably from the energy collection module to a solar heating module; collecting solar energy, preferably using the solar heating module; and heating the transferred water; preferably using the solar heating module.

[0027] According to another aspect of the invention, there is provided a method for filtering water, comprising: providing a filter and a valve; and opening the valve in response to a drop in differential pressure across the filter thereby to allow fluid to flow onto the filter for cleaning.

[0028] The present invention may provide a modular power generation system and a solar power generation system which utilize marine currents in a combined manner, and can achieve seawater desalination while generating power. The investment recovery period for the entire facility may thereby be reduced.

[0029] To describe the aforementioned aspects in other words, in a further aspect, the present invention may adopt the following technical solution.

[0030] A combined power generation and seawater desalination system, comprising: a marine current energy collection system (1) located in seawater, a solar energy collection system (2) located on the sea surface, and, located on land, a thermal power generation system (3), a seawater desalination system (4) and a marine current power generation system (5), with all of the systems being interconnected by pipelines; wherein the marine current energy collection system (1) comprises: a foundation pile (101), a backwashing filter (102), a seawater pump (103) and a water turbine (104); the foundation pile (101) is fixed to the seabed, the water turbine (104) is mounted on the foundation pile (101) and can be freely rotatable, an output shaft of the water turbine (104) is connected to a drive shaft of the seawater pump (103), an inlet of the seawater pump (103) is connected to the backwashing filter (102), and an outlet of the seawater pump (103) is connected to an energy delivery pipe on the sea floor; [0031] when a marine current flows, the water turbine (104) converts kinetic energy of seawater to rotational mechanical energy and acts on the seawater pump (103); the seawater pump (103) converts rotational mechanical energy to high-pressure potential energy, and delivers this to the energy delivery pipe on the sea floor in the form of high-pressure seawater; at the same time, another portion of high-pressure seawater is conveyed to the sea surface through a pipeline, and supplied to a solar power seawater control valve (201);

[0032] the backwashing filter (102) is used to filter large impurities from seawater; moreover, when the backwashing filter (102) has been blocked by impurities, it can use its own high-pressure seawater to perform self-cleaning. [0033] Preferably, the solar energy collection system (2) comprises: the solar power seawater control valve (201) and a solar power heat absorption plate (202); the solar power seawater control valve (201) is mounted on a pipeline connected to the solar power heat absorption plate (202); the solar power heat absorption plate (202) is mounted at a distance of 1 - 3 metres from the sea surface at high tide;

[0034] the function of the solar power heat absorption plate (202) is to absorb solar energy, convert the solar energy to heat, and heat up seawater flowing through the interior thereof. The solar power seawater control valve (201) mainly controls the pressure and flow rate of seawater flowing through the interior of the solar power heat absorption plate (202).

[0035] Preferably, the thermal power generation system (3) comprises: an evaporator (301), a working medium pump (302), a medium turbine (303), a generator (304), a condenser (305) and a water drain pipe (306);

[0036] when high-pressure, high-temperature seawater heated by the solar power heat absorption plate (202) is conveyed to land through a pipeline, and accomplishes the transfer of thermal energy with a medium in the evaporator (301), the seawater which has undergone thermal energy exchange flows back to the sea;

[0037] thermal energy circulates via the medium; when the medium has carried thermal energy to the medium turbine (303), it passes through the medium turbine (303) and then the generator (304) performs conversion to electrical energy;

[0038] the medium must be cooled in the condenser (305) and pressurized by the working medium pump (302) before being recycled.

[0039] Preferably, the source of cooling water of the condenser (305) is wastewater of the marine current power generation system (5); the cooling water flows back to the sea after undergoing heat exchange in the condenser (305);

[0040] after being cooled, the medium is compressed by the working medium pump (302), so as to achieve the objective of recycling.

[0041] The source of motive power for the working medium pump (302) is highly concentrated, low-pressure wastewater in the seawater desalination system (4), and obtained through conversion by a seawater motor (401).

[0042] Preferably, the seawater desalination system (4) comprises: the seawater motor (401) and a reverse osmosis membrane (402); wherein high- pressure seawater obtained through pressure regulation and flow distribution in a power generation and desalination control system (also referred to as a distribution module) (503) enters the reverse osmosis membrane (402), and freshwater is obtained through desalination of the high-pressure seawater by the reverse osmosis membrane (402); [0043] wastewater, which is not desalinated and passes through the reverse osmosis membrane (402), supplies energy to the working medium pump (302) after conversion by the seawater motor (401).

[0044] Preferably, the marine current power generation system (5) comprises: a generator (501), a seawater motor (502), and the power generation and desalination control system (503), wherein high-pressure seawater outputted by the seawater pump (103) is conveyed to land through the sea floor energy delivery pipe, and then after undergoing pressure regulation and flow distribution in the power generation and desalination control system (503), flows into the seawater motor (502); in the seawater motor (502), the high-pressure seawater undergoes conversion to kinetic energy, which is then delivered to the generator (501) to accomplish power generation. After passing through the seawater motor (502), the seawater has no pressure, but is supplied to the condenser (305) as cooling water.

[0045] Preferably, the backwashing filter (102) comprises: a differential pressure valve (10301), a jet head fixing frame (10302), a rotary jet head (10303) and a filter mesh (10304);

[0046] wherein when the filter mesh (10304) is blocked and the seawater pump (103) is operating normally, the pressure in the interior of the filter mesh (10304) will drop; when a pressure drop model number is transmitted to a rod chamber of a piston of the differential pressure valve (10301), then due to the fact that there is no change in a rodless chamber of the differential pressure valve (10301), the piston of the differential pressure valve (10301) will move forward under the combined pushing action of the external atmosphere and water pressure, until a liquid control one-way valve is opened, allowing high-pressure seawater to flow into the jet head fixing frame (10302), and thereby flow to the rotary jet head (10303).

[0047] Preferably, the rotary jet head (10303) is provided with several small holes in a radial direction, and when high-pressure seawater enters the small holes, jets will be formed rapidly, thereby cleaning blocked filter holes of the filter mesh (10304).

[0048] Preferably, an outermost outlet end of the rotary jet head (10303) is designed as a structure that is perpendicular to the radial direction of the jet head, thus enabling the rotary jet head (10303) to rotate when high-pressure fluid is flowing, and it is thereby possible to effectively clean all positions of the filter mesh (10304).

[0049] Through the adoption of the solution above, the present invention may include the following effects:

[0050] 1. The energy of marine currents and the sun can be utilized.

[0051] 2. Two energy systems complement each other.

[0052] 3. The reverse osmosis membrane is used to desalinate seawater. [0053] Other features and advantages of the present invention will be expounded in the remaining part of this specification, and will become partially obvious from the specification, or will be understood through implementation of the present invention. The object and other advantages of the present invention can be realized and obtained through the structures that are specifically pointed out in the written specification, clauses and claims and the drawings.

[0054] Each of the aspects above may comprise any one or more features mentioned in respect of the other aspects above.

[0055] In this specification the word 'or' can be interpreted in the exclusive or inclusive sense unless stated otherwise. [0056] The disclosure extends to methods, system and/or apparatus substantially as herein described and/or as illustrated in the accompanying drawings.

[0057] The disclosure extends to any novel aspects or features described and/or illustrated herein.

[0058] Any feature in one aspect of the invention may be applied to other aspects of the invention, in any appropriate combination. In particular, method aspects may be applied to system aspects, and vice versa. Furthermore, any, some and/or all features in one aspect can be applied to any, some and/or all features in any other aspect, in any appropriate combination. It should also be appreciated that particular combinations of the various features described and defined in any aspects of the invention can be implemented and/or supplied and/or used independently.

[0059] It should also be appreciated that particular combinations of the various features described and defined in any aspects of the invention can be implemented and/or supplied and/or used independently. The disclosure extends to methods and/or apparatus substantially as herein described with reference to the accompanying drawings.

[0060] It should be noted that the term "comprising" as used in this document means "consisting at least in part of. So, when interpreting statements in this document that include the term "comprising", features other than that or those prefaced by the term may also be present. Related terms such as "comprise" and "comprises" are to be interpreted in the same manner. As used herein, "(s)" following a noun means the plural and/or singular forms of the noun.

[0061] As used herein, means plus function features may be expressed alternatively in terms of their corresponding structure.

[0062] Preferred examples are now described, by way of example only, with reference to the accompanying drawings.

Brief description of the drawings

[0063] The present invention is described in detail below in conjunction with the drawings, to clarify the abovementioned advantages of the present invention. Here:

[0064] Fig. 1 is a structural schematic diagram of the combined power generation and seawater desalination system of the present invention.

[0065] Fig. 2 is a structural schematic diagram of the backwashing filter in the present invention.

Detailed description of the invention

[0066] The present disclosure is described with particular reference to the collection of tidal energy, whereby a tide serves as an example movement of water, and to seawater which serves an example of water to be desalinated. The present disclosure could equally well be applied to the collection and storage of energy from any other movement of water, such as currents (in an ocean, sea, river, and/or any other water body), and to the desalination of water from other water bodies, such as salt-water lakes (e.g. the Dead Sea).

[0067] Modes of implementation of the present invention are explained in detail below in conjunction with the drawings and embodiments, to enable full understanding of the way in which the present invention applies technical means to solve the technical problem, and the process of implementation which achieves the technical effect, and in turn to enable implementation on this basis. It must be explained that various embodiments in the present invention and various features within the embodiments may be combined with each other as long as no conflict results, and all technical solutions thus formed fall within the scope of protection of the present invention.

[0068] Referring to Figure 1, a system for desalinating water comprises: an energy collection module 1, and a desalination module 4. The system may further comprise one or more of: a power generation module 5, a distribution module 503, a solar heating module 2, and a (further) power generation module 3.

[0069] Referring to Figure 2, a self-cleaning device 102 for filtering water comprises: a filter 10304 and a valve 10301 configured to open in response to a drop in differential pressure across the filter 10304. The device may further comprise a head 10303 for outputting fluid from the valve 10301.

[0070] Figs. 1 and 2 show a power generation and seawater desalination system, which utilizes solar energy and marine current energy in a combined manner, and mainly comprises an offshore part and an onshore part, and five sub-systems thereof.

[0071] A marine current energy collection system (1) (also referred to as an energy collection module configured to collect energy from movement of water) is located in seawater, and a solar energy collection system (2) is located on the sea surface; a thermal power generation system (3), a seawater desalination system (4) and a marine current power generation system (5) are all installed on land.

[0072] As shown in fig. 1 , the marine current energy collection system (1) consists of a foundation pile (101), a backwashing filter (102), i.e. a self-cleaning device for filtering water, a seawater pump (103), a water turbine (104) and pipelines thereof; the foundation pile (101) is fixed to the seabed, the water turbine (104) is mounted on the foundation pile (101) and can freely rotate, an output shaft of the water turbine (104) is connected to a drive shaft of the seawater pump (103), an inlet of the seawater pump (103) is connected to the backwashing filter (102), and an outlet of the seawater pump (103) is connected to an energy delivery pipe on the sea floor. The function of the water turbine (104) is to absorb the energy of marine currents. When a marine current flows, the water turbine (104) converts kinetic energy of seawater to rotational mechanical energy and acts on the seawater pump (103); the seawater pump (103) converts rotational mechanical energy to high-pressure potential energy, and delivers this to the energy delivery pipe (and thereon to the desalination system (4) and/or the marine current power generation system (5)) on the sea floor in the form of high-pressure seawater; at the same time, another portion of high-pressure seawater is conveyed to the sea surface through a pipeline, and supplied to a solar power seawater control valve (201). The function of the backwashing filter (102) is to filter large impurities from seawater. Moreover, when the backwashing filter (102) has been blocked by impurities, it can use its own high-pressure seawater to perform self-cleaning.

[0073] The solar energy collection system (2) (also referred to as a solar heating module) mainly consists of the solar power seawater control valve (201), a solar power heat absorption plate (202) and pipelines thereof. The solar power seawater control valve (201) is mounted on the sea floor energy delivery pipe and the solar power heat absorption plate (202); the solar power heat absorption plate (202) is mounted at a distance of 1 - 3 metres from the sea surface at high tide. The function of the solar power heat absorption plate (202) is to absorb solar energy, convert the solar energy to heat, and heat up seawater flowing through the interior thereof. The solar power seawater control valve (201) mainly controls the pressure and flow rate of seawater flowing through the interior of the solar power heat absorption plate (202). [0074] The thermal power generation system (3) (also referred to as a further power generation module) mainly consists of an evaporator (301), a working medium pump (302), a medium turbine (303), a generator (304), a condenser (305), a water drain pipe (306) and pipelines thereof. The thermal power generation system (3) operates in a closed loop cycle. When high-pressure, high-temperature seawater heated by the solar power heat absorption plate (202) is conveyed to land through a pipeline, and accomplishes the transfer of thermal energy with a medium in the evaporator (301), the seawater which has undergone thermal energy exchange flows back to the sea. Thermal energy circulates via the medium; when the medium has carried thermal energy to the medium turbine (303), it passes through the medium turbine (303) and then the generator (304) performs conversion to electrical energy. The medium must be cooled in the condenser (305) and pressurized by the working medium pump (302) before being recycled. The source of cooling water of the condenser (305) is wastewater of the marine current power generation system (5); the cooling water flows back to the sea after undergoing heat exchange in the condenser (305). After being cooled, the medium requires the working medium pump (302) in order to be compressed, so as to achieve the objective of recycling. The source of motive power for the working medium pump (302) is highly concentrated, low-pressure wastewater in the seawater desalination system (4), and is obtained through conversion by a seawater motor (401).

[0075] The seawater desalination system (4) (also referred to as a desalination module) mainly consists of the seawater motor (401), a reverse osmosis membrane (402) and pipelines thereof. High-pressure seawater obtained through pressure regulation and flow distribution in a power generation and desalination control system (also referred to as a distribution module) (503) enters the reverse osmosis membrane (402), and freshwater is obtained through (passive) desalination of the high-pressure seawater by the reverse osmosis membrane (402). Wastewater, which is not desalinated and passes through the reverse osmosis membrane (402), supplies energy to the working medium pump (302) after conversion by the seawater motor (401).

[0076] The marine current power generation system (5) mainly consists of a generator (501 ), a seawater motor (502), the power generation and desalination control system (503) and pipelines thereof. High-pressure seawater outputted by the seawater pump (103) is conveyed to land through the sea floor energy delivery pipe, and then after undergoing pressure regulation and flow distribution in the power generation and desalination control system (503), flows into the seawater motor (502); in the seawater motor (502), the high-pressure seawater undergoes conversion to kinetic energy, which is then delivered to the generator (501) to accomplish power generation. After passing through the seawater motor (502), the seawater has no pressure, but is supplied to the condenser (305) as cooling water.

[0077] The power generation and desalination control system (distribution module) (503) is a comprehensive control system comprising a check valve, overflow valve, flow distribution valve, and pressure relief valve (not shown). After the high-pressure seawater in the submarine pipeline enters into the system (503), it passes through the check valve to prevent the backflow of high- pressure seawater. The overflow valve sets the maximum pressure to allow the system to operate safely. The main function of the flow distribution valve is to allocate suitable seawater to the marine current power generation system (5) and the seawater desalination system (4) according to their needs (or, e.g. the need of the operator of systems (4) and (5) which may at various points in time prioritise power generation over desalination and vice versa). Since the pressure required by the marine current power generation system (5) and the seawater desalination system (4) is not exactly the same, a pressure reducing valve is required to adjust the pressure (at the inlets to each of the marine current power generation system (5) and the seawater desalination system (4)) to the optimal working pressure. As will be appreciated, the power generation and desalination control system (503) is thereby capable of selectively transferring water to both of the marine current power generation system (5) and the seawater desalination system (4), where water may be transferred to the inlet of each at different pressures/flow rates.

[0078] As shown in fig. 2, the backwashing filter 102 consists of four parts, namely a differential pressure valve (10301), a jet head fixing frame (10302), a rotary jet head (10303) and a filter mesh (10304). When the filter mesh (10304) is blocked and the seawater pump (103) is operating normally, the pressure in the interior of the filter mesh (10304) will drop; when a pressure drop model number is transmitted to a rod chamber of a piston of the differential pressure valve (10301), then due to the fact that there is no change in a rodless chamber of the differential pressure valve (10301), the piston of the differential pressure valve (10301) will move forward under the combined pushing action of the external atmosphere and water pressure, until a liquid control one-way valve is opened, allowing high-pressure seawater to flow into the jet head fixing frame (10302), and thereby flow to the rotary jet head (10303); the rotary jet head (10303) is provided with several small holes in a radial direction, and when the high-pressure seawater enters the small holes, jets will be formed rapidly, thereby cleaning blocked filter holes of the filter mesh (10304). An outermost outlet end of the rotary jet head (10303) is designed as a structure that is perpendicular to the radial direction of the jet head, thus enabling the rotary jet head (10303) to rotate when high-pressure fluid is flowing, and it is thereby possible to effectively clean all positions of the filter mesh (10304).

[0079] In the present invention, the marine current power generation system and solar power generation system are linked and merged with each other, greatly increasing the power generation efficiency, and making full use of the energy thereof. Moreover, by using the reverse osmosis membrane to perform seawater desalination, the effect of using a single system for multiple purposes is achieved.

[0080] In general terms, the combined power generation and seawater desalination system may comprise: a marine current energy collection system (1) located in seawater, a solar energy collection system (2) located on the sea surface, and, located on land, a thermal power generation system (3), a seawater desalination system (4) and a marine current power generation system (5), with all of the systems being interconnected by pipelines; wherein the marine current energy collection system (1) may comprise: a foundation pile

(101), a backwashing filter (102), a seawater pump (103) and a water turbine (104); the foundation pile (101 ) is fixed to the seabed, the water turbine (104) is mounted on the foundation pile (101 ) and can be freely rotatable, an output shaft of the water turbine (104) is connected to a drive shaft of the seawater pump (103), an inlet of the seawater pump (103) is connected to the backwashing filter

(102), and an outlet of the seawater pump (103) is connected to an energy delivery pipe on the sea floor.

[0081] As will be appreciated, multiple marine current energy collection systems (1) may be used, where each transfers water to the power generation and desalination control system (503).

[0082] Finally, it should be explained that the above are merely preferred embodiments of the present invention, which are not intended to limit it. Although the present invention has been explained in detail with reference to the embodiments above, those skilled in the art can still make amendments to the technical solution recorded in the embodiments above, or make equivalent substitutions of some of the technical features therein. Any amendments, equivalent substitutions or improvements, etc. which are made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Alternative Examples and Embodiments [0083] A person skilled in the art will appreciate that many different combinations of embodiments and examples described with reference to Figures 1 to 2 may be used alone unmodified or in combination with each other. [0084] The described examples of the invention are only examples of how the invention may be implemented. Modifications, variations and changes to the described examples will occur to those having appropriate skills and knowledge. These modifications, variations and changes may be made without departure from the scope of the claims.

CLAUSES

The invention is further illustrated by the following clauses. The following clauses serve to illustrate the possibilities of combining different features of the invention in order to arrive at an embodiment according to the invention.

5

1. Combined power generation and seawater desalination system, characterized by comprising: a marine current energy collection system (1) located in seawater, a solar energy collection system (2) located on the sea0 surface, and, located on land, a thermal power generation system (3), a seawater desalination system (4) and a marine current power generation system (5), with all of the systems being interconnected by pipelines; wherein the marine current energy collection system (1) comprises: a foundation pile

(101), a backwashing filter (102), a seawater pump (103) and a water turbine5 (104); the foundation pile (101 ) is fixed to the seabed, the water turbine (104) is mounted on the foundation pile (101 ) and can be freely rotatable, an output shaft of the water turbine (104) is connected to a drive shaft of the seawater pump (103), an inlet of the seawater pump (103) is connected to the backwashing filter

(102), and an outlet of the seawater pump (103) is connected to an energy 0 delivery pipe on the sea floor; when a marine current flows, the water turbine (104) converts kinetic energy of seawater to rotational mechanical energy and acts on the seawater pump (103); the seawater pump (103) converts rotational mechanical energy to high-pressure potential energy, and delivers this to the energy delivery pipe on 5 the sea floor in the form of high-pressure seawater; at the same time, another portion of high-pressure seawater is conveyed to the sea surface through a pipeline, and supplied to a solar power seawater control valve (201); the backwashing filter (102) is used to filter large impurities from seawater; moreover, when the backwashing filter (102) has been blocked by 0 impurities, it can use its own high-pressure seawater to perform self-cleaning.

2. Combined power generation and seawater desalination system according to Clause 1 , characterized in that the solar energy collection system (2) comprises: the solar power seawater control valve (201) and a solar power heat absorption 5 plate (202); the solar power seawater control valve (201) is mounted on a pipeline connected to the solar power heat absorption plate (202); the solar power heat absorption plate (202) is mounted at a distance of 1 - 3 metres from the sea surface at high tide; the function of the solar power heat absorption plate (202) is to absorb 0 solar energy, convert the solar energy to heat, and heat up seawater flowing through the interior thereof; the solar power seawater control valve (201 ) mainly controls the pressure and flow rate of seawater flowing through the interior of the solar power heat absorption plate (202). 5 3. Combined power generation and seawater desalination system according to

Clause 1 or 2, characterized in that the thermal power generation system (3) comprises: an evaporator (301), a working medium pump (302), a medium turbine (303), a generator (304), a condenser (305) and a water drain pipe (306); when high-pressure, high-temperature seawater heated by the solar 0 power heat absorption plate (202) is conveyed to land through a pipeline, and accomplishes the transfer of thermal energy with a medium in the evaporator (301), the seawater which has undergone thermal energy exchange flows back to the sea; thermal energy circulates via the medium; when the medium has carried thermal energy to the medium turbine (303), it passes through the medium turbine (303) and then the generator (304) performs conversion to electrical energy; the medium must be cooled in the condenser (305) and pressurized by the working medium pump (302) before being recycled.

4. Combined power generation and seawater desalination system according to Clause 3, characterized in that the source of cooling water of the condenser (305) is wastewater of the marine current power generation system (5); the cooling water flows back to the sea after undergoing heat exchange in the condenser (305); after being cooled, the medium is compressed by the working medium pump (302), so as to achieve the objective of recycling; the source of motive power for the working medium pump (302) is highly concentrated, low-pressure wastewater in the seawater desalination system (4), and is obtained through conversion by a seawater motor (401).

5. Combined power generation and seawater desalination system according to Clause 4, characterized in that the seawater desalination system (4) comprises: the seawater motor (401) and a reverse osmosis membrane (402); wherein high-pressure seawater obtained through pressure regulation and flow distribution in a power generation and desalination control system (503) enters the reverse osmosis membrane (402), and freshwater is obtained through desalination of the high-pressure seawater by the reverse osmosis membrane (402); wastewater, which is not desalinated and passes through the reverse osmosis membrane (402), supplies energy to the working medium pump (302) after conversion by the seawater motor (401).

6. Combined power generation and seawater desalination system according to Clause 5, characterized in that the marine current power generation system (5) comprises: a generator (501), a seawater motor (502), and the power generation and desalination control system (503), wherein high-pressure seawater outputted by the seawater pump (103) is conveyed to land through the sea floor energy delivery pipe, and then after undergoing pressure regulation and flow distribution in the power generation and desalination control system (503), flows into the seawater motor (502); in the seawater motor (502), the high- pressure seawater undergoes conversion to kinetic energy, which is then delivered to the generator (501) to accomplish power generation; after passing through the seawater motor (502), the seawater has no pressure, but is supplied to the condenser (305) as cooling water.

7. Combined power generation and seawater desalination system according to Clause 1 , characterized in that the backwashing filter (102) comprises: a differential pressure valve (10301), a jet head fixing frame (10302), a rotary jet head (10303) and a filter mesh (10304); wherein when the filter mesh (10304) is blocked and the seawater pump (103) is operating normally, the pressure in the interior of the filter mesh (10304) will drop; when a pressure drop model number is transmitted to a rod chamber of a piston of the differential pressure valve (10301), then due to the fact that there is no change in a rodless chamber of the differential pressure valve (10301), the piston of the differential pressure valve (10301) will move forward under the combined pushing action of the external atmosphere and water pressure, until a liquid control one-way valve is opened, allowing high-pressure seawater to flow into the jet head fixing frame (10302), and thereby flow to the rotary jet head (10303).

8. Combined power generation and seawater desalination system according to Clause 7, characterized in that the rotary jet head (10303) is provided with several small holes in a radial direction, and when high-pressure seawater enters the small holes, jets will be formed rapidly, thereby cleaning blocked filter holes of the filter mesh (10304).

9. Combined power generation and seawater desalination system according to Clause 8, characterized in that an outermost outlet end of the rotary jet head (10303) is designed as a structure that is perpendicular to the radial direction of the jet head, thus enabling the rotary jet head (10303) to rotate when high- pressure fluid is flowing, and it is thereby possible to effectively clean all positions of the filter mesh (10304).

Claims

1. A system for desalinating water, comprising: an energy collection module configured to collect energy from movement of water; and a desalination module configured to desalinate water; wherein water is transferred from the energy collection module to the desalination module using the collected energy.

2. A system according to Claim 1 , wherein the desalination module is passive.

3. A system according to Claim 2, wherein the desalination module comprises a semipermeable membrane configured to receive water; preferably wherein the semipermeable membrane is a reverse osmosis membrane.

4. A system according to any preceding claim, wherein the desalination module is positioned on land, preferably above sea level.

5. A system according to any preceding claim, further comprising a distribution module configured to receive water from the energy collection module; preferably being configured to distribute water to the desalination module.

6. A system according to Claim 5, wherein the distribution module is configured to control water pressure at an inlet to the desalination module.

7. A system according to Claim 5 or 6, further comprising a power generation module for generating electricity from movement of water; wherein the distribution module is in fluid communication with the desalination module and power generation module.

8. A system for desalinating water and generating power, comprising: a distribution module configured to receive water; a desalination module configured to desalinate water; and a power generation module for generating electricity from movement of water; wherein the distribution module is in fluid communication with the desalination module and power generation module.

9. A system according to Claim 7 or 8, wherein the system is capable of transferring water selectively from the distribution module to either of the desalination module and power generation module.

10. A system according to any of Claims 7 to 9, wherein the system is capable of transferring water selectively from the distribution module to both of the desalination module and power generation module.

11. A system according to any of Claims 7 to 10, wherein the distribution module is configured to control the water pressure at respective inlets of the desalination module and the power generation module.

12. A system according to any of Claims 7 to 11 , wherein the distribution module is configured to provide water to the desalination module and to the power generation module at different water pressures and/or different

5 flow rates.

13. A system according to any of Claims 7 to 12, wherein the distribution module comprises valves for controlling water flow. 0

14. A system according to any of Claims 7 to 13, wherein the power generation module comprises a water motor; and a generator powered by the water motor.

15. A system according to any of Claims 8 to 14, further comprising an 5 energy collection module configured to collect energy from movement of water; wherein water is transferred from the energy collection module to the distribution module using the collected energy.

16. A system according to any of Claims 1 to 7 or 15, wherein the energy 0 collection module comprises a pump for pumping water to the desalination module; the pump being powered by the collected energy.

17. A system according to Claim 16, wherein the energy collection module comprises a turbine for collecting energy from the movement of water; 5 wherein the pump is driven directly by the turbine.

18. A system according to Claim 16, wherein the energy collection module comprises a submerged foundation pile on which the turbine is mounted. 0

19. A system according to any of Claims 1 to 7 or 15 to 18, comprising a plurality of energy collection modules.

20. A system according to any of Claims 1 to 7 or 15 to 19, further comprising a solar heating module configured to collect solar energy and to heat 5 water; wherein water is transferred from the energy collection module to the solar heating module using the energy collected by the energy collection module.

21. A system for collecting energy, comprising: 0 an energy collection module configured to collect energy from movement of water; and a solar heating module configured to collect solar energy and to heat water; wherein water is transferred from the energy collection module to the5 solar heating module using the energy collected by the energy collection module.

22. A system according to Claim 20 or 21 , further comprising a further power generation module for generating electricity from energy stored in water; 0 the further power generation module being connected to the solar heating module.

23. A system according to Claim 22, wherein the further power generation module is configured to generate electricity from the thermal energy of the water received from the solar heating module.

24. A system according to Claim 23, wherein the further power generation module operates in a closed-loop cycle; preferably wherein the further power generation module comprises a heat exchanger configured to extract the thermal energy and to heat a medium; a turbine running on the medium; a generator powered by the turbine; a condenser for condensing the medium; and a pump for conveying the medium from the condenser to the heat exchanger.

25. A system according to any of Claims 22 to 24 when dependent on any of Claims 1 to 20, wherein the further power generation module comprises a pump powered by the flow of wastewater from the desalination module; preferably wherein the system further comprises a water motor configured to run on wastewater from the desalination module to power the pump.

26. A system according to any of Claims 22 to 25 when dependent on any of Claims 7 to 20, wherein the further power generation module comprises a condenser configured to receive wastewater from the power generation module; preferably wherein said wastewater is used as a coolant.

27. A system according to any of Claims 22 to 26, wherein the further power generation module is positioned on land, preferably above sea level.

28. A system according to any of Claims 20 to 27, wherein the solar heating module is positioned at sea; preferably generally above the energy collection module.

29. A system according to any of Claims 1 to 7 or 15 to 28, wherein the energy collection module comprises a self-cleaning device for filtering water, the device being configured to filter impurities from water prior to the water being transferred from the energy collection module.

30. A self-cleaning device for filtering water, comprising: a filter; and a valve configured to open in response to a drop in differential pressure across the filter thereby to allow fluid to flow onto the filter for cleaning.

31. A device according to Claim 30, further comprising a head for outputting fluid from the valve.

32. A device according to Claim 31, wherein the head comprises a plurality of apertures, such that fluid is outputted from the head as a plurality of jets.

33. A device according to Claim 32, wherein the head is configured to rotate in use.

34. A device according to Claim 33, wherein the head comprises a further aperture arranged generally perpendicular to the plurality of apertures, such that the jet output via the further aperture causes the head to rotate in use.

35. A self-cleaning water filter according to any of Claims 30 to 34, further comprising a chamber holding the filter; and a piston used to control the valve.

36. A device according to Claim 35, further comprising a pressurized chamber used to control the valve.

37. A device according to any of Claims 30 to 36, wherein the device is at least partially submerged such that surrounding water acts as the cleaning fluid.

38. A device according to Claim 37, wherein the water is provided to the filter at a pressure of at least 200 kPa.

39. A water pump comprising the device of any of Claims 30 to 38, wherein the device is positioned between a pump suction port and a pump outlet.

40. A system according to Claim 29, wherein the device is the device of any of Claims 30 to 38.

41. A method for desalinating water, comprising: collecting energy from movement of water, preferably using an energy collection module; transferring water using the collected energy, preferably from the energy collection module to a desalination module; and desalinating the transferred water; preferably using the desalination module.

42. A method for desalinating water and generating power, comprising: receiving water; transferring the water selectively to either or both of a desalination module and a power generation module; using the desalination module, desalinating the water; and using the power generation module, generating power from the movement of water.

43. A method for collecting energy, comprising: collecting energy from movement of water, preferably using an energy collection module; transferring water using the collected energy, preferably from the energy collection module to a solar heating module; collecting solar energy, preferably using the solar heating module; and heating the transferred water; preferably using the solar heating module.

44. A method for filtering water, comprising: providing a filter and a valve; and opening the valve in response to a drop in differential pressure across the filter thereby to allow fluid to flow onto the filter for cleaning.