Fresh water-hydrogen comprehensive supply system based on ocean current energy

Abstract

The invention discloses a fresh water-hydrogen comprehensive supply system based on ocean current energy. Comprising a direct-driven transmission system, a seawater desalination system, a water electrolysis hydrogen production system and an exchange system, the direct-driven transmission system is used for power supply and transmission, the seawater desalination system is used for seawater desalination, the water electrolysis hydrogen production system is used for water electrolysis hydrogen production, and the exchange system is used for resource exchange between the seawater desalination system and the water electrolysis hydrogen production system. The method comprises an energy recovery device working method, a seawater desalination method and a water electrolysis hydrogen production method. Fresh water and hydrogen produced by the seawater desalination method and the water electrolysis hydrogen production method exchange resources through an exchange system. The comprehensive supply system can be widely applied to development of remote islands and deep seas, stable power, fresh water and hydrogen supply is provided, and a technical support is provided for achieving the dual-carbon target and promoting construction of the ocean.

Description

Technical Field

[0001] The present invention relates to the field of ocean energy utilization, and in particular to a fresh water-hydrogen integrated supply system based on ocean current energy. Background Art

[0002] As global climate change and resource depletion become increasingly serious, the development and utilization of renewable energy has become the focus of international attention. As a renewable energy source, ocean current energy has the advantages of abundant resources, strong predictability, and low environmental impact, and has gradually become a hot spot in the energy field. However, due to their remote geographical location and weak infrastructure, conventional water resources and energy supply are extremely difficult in remote areas and islands with "three noes" (no water, no electricity, and no fuel), which seriously affects the local quality of life and economic development.

[0003] Traditional energy and fresh water supply methods, such as fossil fuel power generation and land water transport, are not only costly but also impose a heavy burden on the environment. Therefore, there is an urgent need to develop a new system that uses renewable energy for energy and fresh water supply. Existing ocean current energy technology mainly focuses on power generation, but in practical applications it still faces problems such as low energy utilization efficiency and poor equipment reliability.

[0004] To solve the above problems, the present invention proposes a freshwater-hydrogen integrated supply system based on ocean current energy. The system realizes efficient utilization of ocean current energy and provides a stable supply of fresh water and hydrogen through a direct-drive ocean current energy unit transmission system, efficient seawater desalination technology and advanced water electrolysis hydrogen production technology, providing a feasible solution to the energy and water shortage problems in remote areas and islands. The present invention not only helps to improve the level of development and utilization of ocean current energy, but also plays an important role in achieving carbon neutrality goals and marine economic development. Summary of the invention

[0005] The purpose of the present invention is to provide a fresh water-hydrogen integrated supply system based on ocean current energy, including a direct-drive ocean current energy unit transmission system, a seawater desalination system and a water electrolysis hydrogen production system. The system can realize the efficient utilization of ocean current energy and improve the stable supply of fresh water and hydrogen. It is particularly suitable for remote areas and "three-no" (no water, no electricity, no fuel) islands, aiming to solve the resource shortage problem in these areas and improve the local quality of life and economic development level.

[0006] The technical solution adopted by the present invention is as follows:

[0007] 1. A comprehensive fresh water-hydrogen supply system based on ocean current energy

[0008] It includes a direct-drive transmission system, a seawater desalination system, a water electrolysis hydrogen production system and an exchange system; the direct-drive transmission system is a power supply and transmission system in the fresh water-hydrogen integrated supply system, the seawater desalination system is a system for preparing fresh water from seawater in the fresh water-hydrogen integrated supply system, the water electrolysis hydrogen production system is a system for preparing hydrogen from water by electrolysis in the fresh water-hydrogen integrated supply system, and the exchange system is a system for exchanging resources between the seawater desalination system and the water electrolysis hydrogen production system;

[0009] The input end of the direct-drive transmission system is connected to an impeller, and the output end of the direct-drive transmission system is respectively connected to a seawater desalination system and a water electrolysis hydrogen production system; the direct-drive transmission system converts kinetic energy of seawater into electrical energy, and supplies the electrical energy to the water electrolysis hydrogen production system; a part of the hydrogen prepared by the water electrolysis hydrogen production system is processed by an exchange system and used for power supply of the seawater desalination system, and another part is used for industrial production or as energy storage fuel; the direct-drive transmission system transports the extracted seawater to the seawater desalination system, a part of the fresh water prepared by the seawater desalination system is processed by an exchange system and used for hydrogen preparation in the water electrolysis hydrogen production system, and another part is used for domestic water.

[0010] The direct-drive transmission system includes a generator, a speed increaser, a speed encoder, an electromagnetic clutch and a seawater pump; one end of the impeller's transmission shaft is connected to the blades, the other end of the impeller's transmission shaft is transmission-connected to one end of the generator's transmission shaft, the other end of the generator's transmission shaft is transmission-connected to the input shaft of the speed increaser, the generator's power output end is connected to the water electrolysis hydrogen production system, the output shaft of the speed increaser is coaxially transmission-connected to the speed encoder, the electromagnetic clutch and the transmission end of the seawater pump in sequence, and the outlet of the seawater pump is connected to the seawater desalination system.

[0011] The seawater desalination system includes a flushing pump, a pressure gauge, a flow meter, an energy recovery device, a reverse osmosis element, an accumulator and four solenoid valves; the flushing pump is arranged below the energy recovery device, the reverse osmosis element and the accumulator are both arranged above the energy recovery device, the reverse osmosis element is arranged on the front side of the accumulator, the pressure gauge and the flow meter are arranged on the left and right sides of the energy recovery device respectively, the four solenoid valves are respectively arranged at the fresh water outlet and the concentrated brine outlet of the reverse osmosis element and the permeate outlet and the energy recovery outlet of the flushing pump, the inlet of the flushing pump is connected to the outlet of the seawater pump of the direct drive transmission system, the permeate outlet, the energy recovery outlet and the flow outlet of the flushing pump are respectively connected to the inlet of the reverse osmosis element, the energy recovery device and the inlet of the flow meter, the outlet of the flow meter is connected to the inlet of the pressure gauge, the fresh water outlet of the reverse osmosis element is respectively connected to the exchange system and the water storage tank, the concentrated brine outlet of the reverse osmosis element is respectively connected to the energy recovery device and the wastewater tank, and the energy recovery device is also connected to the accumulator.

[0012] The energy recovery device includes a boost cylinder 1, a boost cylinder 2, a piston rod, a proximity switch 1 and a proximity switch 2; one end of the boost cylinder 1 is connected to one end of the boost cylinder 2, a distributor is arranged in the middle of the connecting position, the cavity of the boost cylinder 1 and the cavity of the boost cylinder 2 are connected through the piston rod, the other end of the boost cylinder 1 is respectively connected to the reverse osmosis element and the flushing pump, the other end of the boost cylinder 2 is respectively connected to the reverse osmosis element and the flushing pump, the proximity switch 1 is arranged at the other end of the boost cylinder 1, the proximity switch 2 is arranged at the other end of the boost cylinder 2, the concentrated brine outlet of the reverse osmosis element is connected to the inlet 1 or the inlet 2 of the distributor, and the accumulator is respectively connected to the other end of the boost cylinder 1 and the other end of the boost cylinder 2.

[0013] The water electrolysis hydrogen production system comprises a battery, a power conversion device, a water electrolysis hydrogen production device, a hydrogen processing device and a hydrogen detection device; the water electrolysis hydrogen production device comprises a PEM electrolyzer and a hydrogen transmitter; the hydrogen processing device comprises a hydrogen dryer and a gas-water separator; the hydrogen detection device comprises a hydrogen flowmeter and a purity analyzer; the power output end of the generator of the direct drive transmission system is respectively connected to the input end of the battery and the input end of the power conversion device, and the input end of the power conversion device is also connected to the output end of the battery, the raw material port of the PEM electrolyzer of the water electrolysis hydrogen production device is connected to the exchange system, the power port of the PEM electrolyzer is connected to the output end of the power conversion device, the hydrogen output port of the PEM electrolyzer is connected to the input end of the hydrogen transmitter, the gas-water separator of the hydrogen processing device is respectively connected to the output end of the hydrogen transmitter and the input end of the hydrogen dryer, the hydrogen flowmeter is respectively connected to the output end of the hydrogen dryer and the input end of the purity analyzer, and the output end of the purity analyzer is respectively connected to the exchange system and the hydrogen tank.

[0014] The exchange system comprises a fresh water deionization tank and a hydrogen processing station; the fresh water deionization tank deionizes fresh water prepared by the seawater desalination system and uses it in the electrolytic water hydrogen production system, and the hydrogen processing station processes the hydrogen prepared by the electrolytic water hydrogen production system and converts it into electrical energy for use in the seawater desalination system; the inlet of the fresh water deionization tank is connected to the outlet of the reverse osmosis element of the seawater desalination system, and the outlet of the fresh water deionization tank is connected to the raw material port of the PEM electrolyzer of the electrolytic water hydrogen production system; the inlet of the hydrogen processing station is connected to the output end of the purity analyzer of the electrolytic water hydrogen production system, and the outlet of the hydrogen processing station is connected to the accumulator (19).

[0015] The fresh water-hydrogen integrated supply system based on ocean current energy also includes a control system; the control system is respectively connected to the direct drive transmission system, the seawater desalination system and the water electrolysis hydrogen production system.

[0016] 2. An energy recovery method for a fresh water-hydrogen integrated supply system based on ocean current energy, comprising the following steps:

[0017] The solenoid valve at the concentrated brine outlet of the reverse osmosis element controls the inlet of the distributor of the energy recovery device to connect with the concentrated brine outlet of the reverse osmosis element. When inlet 1 of the distributor is connected to the concentrated brine outlet of the reverse osmosis element, it is a left-hand movement mode. When inlet 2 of the distributor is connected to the concentrated brine outlet of the reverse osmosis element, it is a right-hand movement mode. When the two ends of the piston rod contact proximity switch 1 and proximity switch 2 respectively, the solenoid valve at the concentrated brine outlet will be triggered to switch the inlet of the distributor and change the movement mode. When the solenoid valve at the concentrated brine outlet is switched to the left movement mode, the concentrated brine outlet of the reverse osmosis element is connected to the inlet one of the distributor, and the concentrated brine in the concentrated brine outlet of the reverse osmosis element flows into the cavity with the piston rod of the booster cylinder one through the inlet one of the distributor, pushing the piston rod to move to the left, and the liquid in the cavity without the piston rod of the booster cylinder one flows into the reverse osmosis element. At this time, the solenoid valve at the energy recovery outlet of the flushing pump controls the seawater treated by the flushing pump to flow into the cavity without the piston rod of the booster cylinder two, further pushing the piston rod to move to the left, and the liquid in the cavity with the piston rod of the booster cylinder two is discharged as waste concentrated brine. When the piston rod moves to the left until it touches the proximity switch one, the solenoid valve at the concentrated brine outlet is switched to the right working mode. When the solenoid valve at the brine outlet switches to rightward movement, the brine outlet of the reverse osmosis element is connected to the inlet 2 of the distributor, and the brine in the brine outlet of the reverse osmosis element flows into the cavity with the piston rod of the booster cylinder 2 through the inlet 2 of the distributor, pushing the piston rod to move to the right. At this time, the solenoid valve at the energy recovery outlet of the flushing pump controls the seawater treated by the flushing pump to flow into the cavity without the piston rod of the booster cylinder 1, further pushing the piston rod to move to the right, and the liquid in the cavity without the piston rod of the booster cylinder 2 flows into the reverse osmosis element, and the liquid in the cavity with the piston rod of the booster cylinder 1 is discharged as waste brine. When the piston rod moves to the right until it contacts the proximity switch 2, the solenoid valve at the brine outlet switches to the leftward working mode. The energy generated by the movement of the booster cylinder 1 and the booster cylinder 2 is transmitted to the accumulator for storage.

[0018] 3. A method for producing hydrogen by desalination of seawater and electrolysis of water in a freshwater-hydrogen integrated supply system based on ocean current energy, comprising the following steps:

[0019] The impeller drives the seawater pump of the direct-drive transmission system to press the seawater into the seawater desalination system for desalination; the impeller drives the direct-drive transmission system to generate electricity and transmit the electricity to the water electrolysis hydrogen production system for hydrogen preparation; the seawater desalination system and the water electrolysis hydrogen production system exchange resources through an exchange system.

[0020] Seawater desalination method: the speed encoder controls the speed of the speed increaser, thereby controlling the amount of seawater pumped by the seawater pump; the electromagnetic clutch controls whether the seawater pump works, thereby controlling whether the seawater desalination system works.

[0021] Hydrogen production method by electrolysis of water: PEM electrolyzer produces hydrogen through the coordinated power supply of batteries and power conversion equipment.

[0022] The desalination method is specifically as follows: the flow of seawater drives the rotation of the impeller, and the rotation of the impeller drives the operation of the seawater pump through the generator, the speed increaser, the speed encoder and the electromagnetic clutch in turn, and the seawater pump presses the seawater into the flushing pump for flushing, and the flushed seawater is transported to the energy recovery device, and the seawater passing through the energy recovery device is further transported to the reverse osmosis element for osmosis and washing to produce fresh water. In the working state, when the speed increaser is controlled by the speed encoder to increase the speed of the transmission shaft, the speed of the transmission shaft of the seawater pump increases, the extracted seawater increases, the seawater transported to the flushing pump increases, and then the fresh water osmosis and washing increases through the energy recovery device and the reverse osmosis unit in turn. When the speed increaser is controlled by the speed encoder to reduce the speed of the transmission shaft, the speed of the transmission shaft of the seawater pump decreases, the extracted seawater decreases, the seawater transported to the flushing pump decreases, and then the fresh water osmosis and washing decreases through the energy recovery device and the reverse osmosis unit in turn. When fresh water needs to be prepared, by switching the electromagnetic clutch to the working state, the rotation of the impeller drives the rotation of the seawater pump, and then fresh water is prepared through the seawater desalination system. When fresh water preparation is not needed, the electromagnetic clutch is switched to a non-working state, and the rotation of the impeller cannot drive the seawater pump, that is, the seawater desalination system stops preparing fresh water.

[0023] The method for producing hydrogen by electrolysis of water is specifically as follows: the flow of seawater drives the rotation of the impeller, and the rotation of the impeller drives the transmission shaft of the generator to rotate to generate electricity, and the generator transmits the electricity to the battery and the power conversion device; when the power generated by the direct-drive transmission system driven by seawater is sufficient, a part of the power is transmitted to the battery for storage, and the other part of the power is transmitted to the power conversion device, and the battery does not transmit power to the power conversion device at this time; when the seawater flow rate decreases and the power generated by the direct-drive transmission system is insufficient, all the generated power is transmitted to the power conversion device, and the power in the battery is transmitted to the power conversion device to maintain the operation of the hydrogen production system by electrolysis of water; when the direction of seawater changes and the direct-drive transmission system does not generate power, the power in the battery is transmitted to the power conversion device to maintain the operation of the hydrogen production system by electrolysis of water.

[0024] The power conversion equipment converts AC power into DC power and transmits it to the PEM electrolyzer. The fresh water prepared by the seawater desalination system is deionized and used as the raw water of the PEM electrolyzer. The PEM electrolyzer electrolyzes the deionized fresh water to prepare hydrogen. The prepared hydrogen is transported to the gas-water separator through the hydrogen transmitter. The hydrogen after gas and water separation is transported to the hydrogen dryer. After drying, the hydrogen passes through the hydrogen flowmeter and purity analyzer in turn and is finally stored in the hydrogen tank.

[0025] The resource exchange between the seawater desalination system and the water electrolysis hydrogen production system is carried out through the exchange system as follows: the seawater desalination system transports the prepared fresh water to the fresh water deionization tank of the exchange system for deionization treatment, and the deionized fresh water is transported to the PEM electrolyzer of the water electrolysis hydrogen production system for hydrogen preparation; the hydrogen prepared by the water electrolysis hydrogen production system is transmitted to the hydrogen processing station of the exchange system for processing and conversion into electrical energy, and the converted electrical energy is transported to the accumulator of the energy recovery device for use by the seawater desalination system.

[0026] The innovation of the present invention lies in that the energy recovery device designed for the seawater desalination system recovers energy from the high-pressure concentrated brine discharged during the seawater desalination process, thereby significantly reducing the specific energy consumption of fresh water production, bringing higher energy recovery efficiency and more energy-saving and environmentally friendly benefits than traditional reverse osmosis systems.

[0027] The innovation of the present invention lies in the collaborative processing method of exchanging resources between the seawater desalination system and the water electrolysis hydrogen production system through an exchange system, which brings the beneficial effects of efficient power supply to the operation of the seawater desalination system and high-purity fresh water supply to the water electrolysis hydrogen production system, thereby realizing the advantage of efficient utilization of resources.

[0028] Compared with the prior art, the present invention has the following outstanding and beneficial technical effects:

[0029] 1. The present invention adopts a direct-drive ocean current energy unit transmission system design, which directly drives the generator and seawater pump through mechanical transmission, reducing the energy conversion loss in the traditional transmission system. This design improves the energy utilization efficiency of ocean current energy. Compared with traditional electric drive or hydraulic drive systems, energy loss is significantly reduced, and the overall energy efficiency of the system is higher. At the same time, the direct-drive ocean current energy unit transmission system does not use components such as hydraulic motors and electric motors, making the direct-drive ocean current energy unit transmission system compact in structure, improved in reliability, and effectively reducing procurement and maintenance costs.

[0030] 2. The present invention integrates the three functions of ocean current energy power generation, seawater desalination and water electrolysis to produce hydrogen, providing a comprehensive solution for electricity, fresh water and hydrogen. Compared with the existing single-function ocean current energy utilization system, the present invention can simultaneously meet the multiple resource needs of remote islands and offshore platforms, improving the practicality and economic benefits of the system.

[0031] 3. The energy recovery device designed by the present invention recovers energy from the high-pressure concentrated brine discharged during the desalination process, significantly reducing the specific energy consumption of fresh water production. Compared with the traditional reverse osmosis system, the energy recovery efficiency of the present invention is higher, making the fresh water production process more energy-saving and environmentally friendly.

[0032] 4. The battery of the water electrolysis hydrogen production system of the present invention serves as an energy storage device to store excess electrical energy during periods of high seawater flow rate or high power generation. When the seawater flow rate decreases or changes direction, resulting in insufficient power generation output, the battery system can quickly release the stored electrical energy to the water electrolysis hydrogen production system. This electrical energy compensation mechanism ensures that the electrolyzer always has sufficient electrical energy supply during the water electrolysis process to maintain its stable operation.

[0033] 5. The present invention adopts the collaborative processing of resource exchange between the seawater desalination system and the water electrolysis hydrogen production system through the exchange system, which brings the beneficial effects of efficient power supply for the operation of the seawater desalination system and high-purity fresh water supply for the water electrolysis hydrogen production system, and realizes the advantage of efficient utilization of resources. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 It is an overall schematic diagram of a fresh water-hydrogen integrated supply system based on ocean current energy of the present invention;

[0035] Figure 2 It is a schematic diagram of the structure of the transmission system of the direct-drive ocean current energy unit of the present invention;

[0036] Figure 3 It is a schematic diagram of the structure of the seawater desalination system of the present invention;

[0037] Figure 4 It is a schematic structural diagram of the water electrolysis hydrogen production system of the present invention;

[0038] Figure 5 Schematic diagram of the energy recovery device of the present invention.

[0039] In the figure: 1. impeller; 2. generator; 3. speed increaser; 4. speed encoder; 5. electromagnetic clutch; 6. seawater pump; 7. flushing pump; 8. pressure gauge; 9. flow meter; 10. solenoid valve; 11. energy recovery device; 12. reverse osmosis element; 13. booster cylinder 1; 14. booster cylinder 2; 15. piston rod; 16. proximity switch 1; 17. proximity switch 2; 18. accumulator. DETAILED DESCRIPTION

[0040] The embodiment of the present invention provides a fresh water-hydrogen integrated supply system based on ocean current energy, which can utilize ocean current energy to generate electricity, and can also stably produce fresh water and hydrogen, providing a feasible solution to the energy and water resource shortage problems in remote areas and islands.

[0041] In order to make the purpose, features and advantages of the present invention more obvious and easy to understand, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the embodiments described below are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. The present invention is further described below in conjunction with specific embodiments:

[0042] like Figure 1-Figure 5 As shown, the fresh water-hydrogen integrated supply system based on ocean current energy of the present invention comprises:

[0043] Direct-drive transmission system, seawater desalination system, water electrolysis hydrogen production system and exchange system; the direct-drive transmission system is a power supply and transmission system in the fresh water-hydrogen integrated supply system, the seawater desalination system is a system for preparing fresh water from seawater in the fresh water-hydrogen integrated supply system, the water electrolysis hydrogen production system is a system for preparing hydrogen from water by electrolysis in the fresh water-hydrogen integrated supply system, and the exchange system is a system for exchanging resources between the seawater desalination system and the water electrolysis hydrogen production system;

[0044] The input end of the direct-drive transmission system is connected to the impeller 1, and the output end of the direct-drive transmission system is respectively connected to the seawater desalination system and the water electrolysis hydrogen production system; the direct-drive transmission system converts ocean current energy into electrical energy, and supplies the electrical energy to the water electrolysis hydrogen production system. A part of the hydrogen prepared by the water electrolysis hydrogen production system is processed by the exchange system for power supply of the seawater desalination system, and the other part is used for industrial production. The direct-drive transmission system transports the extracted seawater to the seawater desalination system. A part of the fresh water prepared by the seawater desalination system is processed by the exchange system for hydrogen preparation by the water electrolysis hydrogen production system, and the other part is used for domestic water.

[0045] The direct drive transmission system includes a dynamic seal assembly, a generator 2, a speed increaser 3, a speed encoder 4, an electromagnetic clutch 5 and a seawater pump 6; the direct drive transmission system is placed in seawater, one end of the drive shaft of the impeller 1 is fixedly connected to the blade, the other end of the drive shaft of the impeller 1 is sealed and connected to one end of the drive shaft of the generator 2, the impeller 1 and the generator 2 are sealed and fixed by a dynamic seal assembly, the other end of the drive shaft of the generator 2 is connected to the input shaft of the speed increaser 3, the power output end of the generator 2 is connected to the water electrolysis hydrogen production system, the output shaft of the speed increaser 3 is coaxially connected to the speed encoder 4, the electromagnetic clutch 5 and the drive end of the seawater pump 6 in turn, the inlet of the seawater pump 6 is placed in seawater, and the seawater outlet of the seawater pump 6 is connected to the seawater desalination system. The generator 2 adopts PMSG.

[0046] The desalination system comprises a flushing pump 7, a pressure gauge 8, a flow meter 9, an energy recovery device 11, a reverse osmosis element 12, an accumulator 18 and four solenoid valves 10; the flushing pump 7 is arranged below the energy recovery device 11, and is used to remove particles, microorganisms and sludge in seawater to meet the requirements of the reverse osmosis element 12 for the inlet water quality; the reverse osmosis element 12 is arranged above the energy recovery device 11; the pressure gauge 8 and the flow meter 9 are arranged on both sides of the energy recovery device 11, and are used to monitor the pressure and flow of seawater in the energy recovery device 11, respectively; the four solenoid valves 10 are arranged at the fresh water outlet and the concentrated brine outlet of the reverse osmosis element 12, and the osmotic outlet and the energy recovery outlet of the flushing pump 7, respectively; the solenoid valve 10 is used to control The switching states of the fresh water outlet and concentrated brine outlet of the reverse osmosis element 12 and the osmotic outlet and energy recovery outlet of the flushing pump 7; the inlet of the flushing pump 7 is connected to the outlet of the seawater pump 6 of the direct drive transmission system; the outlet of the flushing pump 7 is respectively connected to the inlet of the reverse osmosis element 12, the energy recovery device 11 and the inlet of the flow meter 9; the outlet of the flow meter 9 is connected to the inlet of the pressure gauge 8; the other end of the pressure gauge 8 is sealed; the fresh water outlet of the reverse osmosis element 12 is respectively connected to the exchange system and the water reservoir; the concentrated brine outlet of the reverse osmosis element 12 is respectively connected to the energy recovery device 11 and the wastewater tank; the fresh water in the water reservoir is used for domestic water, and the wastewater in the wastewater tank is subjected to the next step of wastewater treatment; the energy recovery device 11 is also connected to the accumulator 18.

[0047] The energy recovery device 11 includes a boost cylinder 13, a boost cylinder 14, a piston rod 15, a proximity switch 16 and a proximity switch 2 17; one end of the boost cylinder 13 is connected to one end of the boost cylinder 14, and a distributor is arranged in the middle of the connection position. The cavity of the boost cylinder 13 and the cavity of the boost cylinder 14 are connected through the piston rod 15. The other end of the boost cylinder 13 is respectively connected to the reverse osmosis element 12 and the flushing pump 7, and the other end of the boost cylinder 14 is respectively connected to the reverse osmosis element 12 and the flushing pump 7. The proximity switch One 16 is arranged at the other end of the boosting cylinder one 13, and the proximity switch two 17 is arranged at the other end of the boosting cylinder two 14. The concentrated brine outlet of the reverse osmosis element 12 is connected to the inlet one of the distributor or the inlet two of the distributor. The matching of the concentrated brine outlet with the inlet one of the distributor or the inlet two of the distributor is controlled by the solenoid valve 10. The accumulator 18 is respectively connected to the other end of the boosting cylinder one 13 and the other end of the boosting cylinder two 14. The energy recovered by the boosting cylinder one 13 and the boosting cylinder two 14 is stored in the accumulator 18 for household power supply.

[0048] The reverse osmosis element 12 is used to intercept solutes and produce fresh water; the safe operating window of the reverse osmosis element 12 is jointly limited by the maximum allowable water supply pressure, maximum water supply flow, maximum recovery rate and maximum allowable water production concentration of the membrane of the reverse osmosis element 12, and is specifically set according to the material of the reverse osmosis element 12, water quality conditions, etc.

[0049] Maximum allowable feed water pressure, which is the highest water inlet pressure that the reverse osmosis element 12 can withstand. Exceeding this pressure may cause physical damage or over-compression of the membrane, affecting the normal operation and life of the membrane. The operating pressure of the reverse osmosis system should be controlled below this upper limit to ensure the structural integrity and stable performance of the membrane.

[0050] Minimum feed water flow rate, which is the minimum water flow rate required for the reverse osmosis system to operate. A flow rate lower than this may cause scaling and contamination on the membrane surface, and even cause a decrease in the operating efficiency of the seawater desalination system. Maintaining sufficient water flow can prevent salt and other impurities from accumulating on the membrane surface, ensuring the permeability of the membrane and the fresh water output.

[0051] Maximum recovery rate, which is the ratio of fresh water production to influent volume in the reverse osmosis system. Too high a recovery rate may lead to excessive concentration of the concentrated solution, thereby increasing the concentration polarization phenomenon on the membrane surface, affecting the membrane's permeability and fresh water quality. Therefore, the recovery rate needs to be within an appropriate range to maximize fresh water production while avoiding damage to the membrane.

[0052] Maximum allowable water concentration, which is the maximum concentration limit of dissolved substances in the fresh water produced by the reverse osmosis system. The water concentration must be controlled within the drinking water standard or other specific application requirements to ensure the quality and safety of the water. By monitoring and adjusting the water concentration, it can be ensured that the water quality of the reverse osmosis system meets the requirements.

[0053] By strictly controlling the operating conditions of the reverse osmosis element 12 within the above-mentioned safe operating window, the service life of the membrane can be effectively extended, the operating efficiency and water quality of the seawater desalination system can be improved, and maintenance and operating costs can be reduced. The monitoring and control devices in the seawater desalination system will monitor these parameters in real time and make adjustments based on the actual operating conditions to ensure that the seawater desalination system operates in the best condition.

[0054] The water electrolysis hydrogen production system includes a battery, a power conversion device, a water electrolysis hydrogen production device, a hydrogen processing device and a hydrogen detection device; the water electrolysis hydrogen production device includes a PEM electrolyzer and a hydrogen transmitter; the hydrogen processing device includes a hydrogen dryer and a gas-water separator; the hydrogen detection device includes a hydrogen flowmeter and a purity analyzer; the power output end of the generator 2 of the direct drive transmission system is respectively connected to the input end of the battery and the input end of the power conversion device, the input end of the power conversion device is also connected to the output end of the battery, and the raw material port of the PEM electrolyzer of the water electrolysis hydrogen production device is It is connected to the exchange system to receive the fresh water treated by the exchange system as the raw water for electrolysis. The power port of the PEM electrolyzer is connected to the output end of the power conversion equipment, the hydrogen output port of the PEM electrolyzer is connected to the input end of the hydrogen transmitter, the gas-water separator of the hydrogen processing equipment is respectively connected to the output end of the hydrogen transmitter and the input end of the hydrogen dryer, the hydrogen flowmeter is respectively connected to the output end of the hydrogen dryer and the input end of the purity analyzer, the output end of the purity analyzer is respectively connected to the exchange system and the hydrogen tank, and the hydrogen in the hydrogen tank is finally used for industrial production.

[0055] The exchange system includes a fresh water deionization tank and a hydrogen processing station; the fresh water deionization tank deionizes the fresh water prepared by the seawater desalination system for use in the electrolytic water hydrogen production system, and the hydrogen processing station processes the hydrogen prepared by the electrolytic water hydrogen production system and converts it into electrical energy for use in the seawater desalination system; the inlet of the fresh water deionization tank is connected to the outlet of the reverse osmosis element 12 of the seawater desalination system to receive the fresh water in the reservoir, and the outlet of the fresh water deionization tank is connected to the raw material port of the PEM electrolyzer of the electrolytic water hydrogen production system; the inlet of the hydrogen processing station is connected to the output end of the purity analyzer of the electrolytic water hydrogen production system, and the outlet of the hydrogen processing station is connected to the accumulator 18; the fresh water-hydrogen comprehensive supply system based on ocean current energy also includes a control system; the control system is respectively connected to the direct drive transmission system, the seawater desalination system and the electrolytic water hydrogen production system.

[0056] The control system mainly includes three types of controls:

[0057] (1) PEM electrolyzer dynamic model building and parameter identification

[0058] Since ocean current energy has significant volatility and intermittency, an electrolytic cell model based on the Hammerstein model structure is established, which mainly includes static part modeling and identification and dynamic part modeling and identification.

[0059] (2) Multi-load operation mode control for intermittent power generation

[0060] In order to avoid frequent switching among the five operating modes (standby, MPPT control, constant speed control, shutdown, and battery supply), hysteresis control is introduced in the emergency judgment of the control system mode switching, so that each component of the system can operate efficiently within the operating power range, realizing the organic combination of the power capture characteristics of ocean current energy and the power input requirements of the two loads.

[0061] (3) Multi-load operation mode control principle

[0062] Its essence is to use power feedback control method to achieve maximum energy capture technology.

[0063] The energy recovery method of the fresh water-hydrogen integrated supply system based on ocean current energy of the present invention is specifically as follows:

[0064] The solenoid valve 10 at the concentrated brine outlet of the reverse osmosis element 12 controls the inlet of the distributor of the energy recovery device 11 to connect with the concentrated brine outlet of the reverse osmosis element 12. When the inlet 1 of the distributor is connected to the concentrated brine outlet of the reverse osmosis element 12, it is in the left-hand movement mode. When the inlet 2 of the distributor is connected to the concentrated brine outlet of the reverse osmosis element 12, it is in the right-hand movement mode. When the two ends of the piston rod 15 contact the proximity switch 1 16 and the proximity switch 2 17 respectively, the solenoid valve 10 at the concentrated brine outlet will be triggered to switch the inlet of the distributor and change the movement mode. When the solenoid valve 10 at the reverse osmosis element 12 is switched to the left movement mode, the concentrated brine outlet of the reverse osmosis element 12 is connected to the inlet 1 of the distributor, and the concentrated brine in the concentrated brine outlet of the reverse osmosis element 12 flows into the cavity with the piston rod 15 of the boosting cylinder 13 through the inlet 1 of the distributor, pushing the piston rod 15 to move leftward, and the liquid in the cavity without the piston rod 15 of the boosting cylinder 13 flows into the reverse osmosis element 12. At this time, the solenoid valve 10 at the energy recovery outlet of the flushing pump 7 controls the seawater treated by the flushing pump 7 to flow into the cavity without the piston rod 15 of the boosting cylinder 2 14, further pushing the piston rod 15 to move leftward. The liquid in the cavity with piston rod 15 of booster cylinder 2 14 is discharged as waste concentrated brine. When piston rod 15 moves to the left until it contacts proximity switch 16, solenoid valve 10 at the concentrated brine outlet switches to right working mode. When solenoid valve 10 at the concentrated brine outlet switches to right movement, the concentrated brine outlet of reverse osmosis element 12 is connected to inlet 2 of distributor, and concentrated brine in the concentrated brine outlet of reverse osmosis element 12 flows into the cavity with piston rod 15 of booster cylinder 2 14 through inlet 2 of distributor, pushing piston rod 15 to move to the right. At this time, the energy recovery outlet of flushing pump 7 The solenoid valve 10 controls the seawater treated by the flushing pump 7 to flow into the cavity without piston rod 15 of the boosting cylinder 1 13, further pushing the piston rod 15 to move to the right, and the liquid in the cavity without piston rod 15 of the boosting cylinder 2 14 flows into the reverse osmosis element 12, and the liquid in the cavity with piston rod 15 of the boosting cylinder 1 13 is discharged as waste concentrated brine. When the piston rod 15 moves to the right until it contacts the proximity switch 2 17, the solenoid valve 10 at the concentrated brine outlet switches to the left working mode; the energy generated by the movement of the boosting cylinder 1 and the boosting cylinder 2 14 is transmitted to the accumulator 18 for storage.

[0065] This process realizes the alternating pressurization of the boost cylinders on both sides and the discharge of waste water, so that the energy recovery device 11 can operate continuously and efficiently.

[0066] The method for producing hydrogen by desalination of seawater and electrolysis of water in the fresh water-hydrogen integrated supply system based on ocean current energy of the present invention is as follows:

[0067] The impeller 1 drives the seawater pump 6 of the direct-drive transmission system to press the seawater into the seawater desalination system for desalination; the impeller 1 drives the direct-drive transmission system to generate electricity and transmits the electricity to the water electrolysis hydrogen production system for hydrogen preparation; the seawater desalination system and the water electrolysis hydrogen production system exchange resources through the exchange system.

[0068] Seawater desalination method: the speed encoder 4 controls the speed of the speed increaser 3, thereby controlling the amount of seawater pumped by the seawater pump 6; the electromagnetic clutch 5 controls whether the seawater pump 6 works, thereby controlling whether the seawater desalination system works.

[0069] Hydrogen production method by electrolysis of water: PEM electrolyzer produces hydrogen through the coordinated power supply of batteries and power conversion equipment.

[0070] The seawater desalination method is specifically as follows: the flow of seawater drives the rotation of the impeller 1, and the rotation of the impeller 1 drives the operation of the seawater pump 6 through the generator 2, the speed increaser 3, the speed encoder 4 and the electromagnetic clutch 5 in turn, and the seawater pump 6 presses the seawater into the flushing pump 7 for flushing, and the flushed seawater is transported to the energy recovery device 11, and the seawater passing through the energy recovery device 11 is further transported to the reverse osmosis element 12 for osmosis and washing to produce fresh water; in the working state, when the speed increaser 3 is controlled by the speed encoder 4 to increase the speed of the transmission shaft, the speed of the transmission shaft of the seawater pump 6 increases, the extracted seawater increases, and the seawater transported to the flushing pump 7 increases, and then passes through the energy recovery device 11 and the reverse osmosis element 12 in turn. The fresh water produced by osmosis cleaning increases; when the speed encoder 4 is used to control the speed increaser 3 to reduce the speed of the transmission shaft, the speed of the transmission shaft of the seawater pump 6 decreases, the extracted seawater decreases, and the seawater transported to the flushing pump 7 decreases, and then passes through the energy recovery device 11 and the reverse osmosis unit in sequence, and the fresh water produced by osmosis cleaning decreases; when fresh water needs to be prepared, the electromagnetic clutch 5 is switched to the working state, and the rotation of the impeller 1 drives the rotation of the seawater pump 6, and then the seawater desalination system is used to prepare fresh water; when fresh water does not need to be prepared, the electromagnetic clutch 5 is switched to the non-working state, and the rotation of the impeller 1 cannot drive the seawater pump 6, that is, the seawater desalination system stops preparing fresh water.

[0071] The specific method of producing hydrogen by electrolysis of water is as follows:

[0072] The flow of seawater drives the rotation of the impeller 1, and the rotation of the impeller 1 drives the transmission shaft of the generator 2 to rotate to generate electricity, and the generator 2 transmits electricity to the battery and the power conversion device; when the power generated by the direct-drive transmission system driven by seawater is sufficient, part of the power is transmitted to the battery for storage, and the other part of the power is transmitted to the power conversion device, and the battery does not transmit power to the power conversion device at this time; when the seawater flow rate decreases and the power generated by the direct-drive transmission system is insufficient, all the generated power is transmitted to the power conversion device, and the power in the battery transmits power to the power conversion device to maintain the operation of the water electrolysis hydrogen production system; when the direction of seawater changes and the direct-drive transmission system does not generate power, the power in the battery transmits power to the power conversion device to maintain the operation of the water electrolysis hydrogen production system;

[0073] The power conversion equipment converts AC power into DC power and transmits it to the PEM electrolyzer. The fresh water prepared by the seawater desalination system is deionized and used as the raw water of the PEM electrolyzer. The PEM electrolyzer electrolyzes the deionized fresh water to prepare hydrogen. The prepared hydrogen is transported to the gas-water separator through the hydrogen transmitter. The hydrogen after gas and water separation is transported to the hydrogen dryer. After drying, the hydrogen passes through the hydrogen flowmeter and purity analyzer in turn and is finally stored in the hydrogen tank.

[0074] The resource exchange between the seawater desalination system and the water electrolysis hydrogen production system is carried out through the exchange system as follows: the seawater desalination system transports the prepared fresh water to the fresh water deionization tank of the exchange system for deionization treatment, and the deionized fresh water is transported to the PEM electrolyzer of the water electrolysis hydrogen production system for hydrogen preparation; the hydrogen prepared by the water electrolysis hydrogen production system is transmitted to the hydrogen processing station of the exchange system for processing and conversion into electrical energy, and the converted electrical energy is transported to the accumulator 18 of the energy recovery device 11 for use by the seawater desalination system.

[0075] Since the speed and direction of the ocean current fluctuate due to natural factors, these fluctuations may cause the output power of the ocean current energy power generation system to be unstable, affecting the normal operation of the water electrolysis hydrogen production system. In order to solve this problem, the battery system is used as an energy storage device to store the excess electric energy of the ocean current energy power generation system during high flow rate or high power generation period. When the ocean current flow rate decreases or the direction changes, resulting in insufficient power generation output, the battery system can quickly release the stored electric energy and provide it to the water electrolysis hydrogen production system. This electric energy compensation mechanism ensures that the electrolyzer always has sufficient electric energy supply during the water electrolysis process to maintain its stable operation. The design of the battery system takes into account the power demand of the water electrolysis hydrogen production system and the fluctuation characteristics of ocean current energy, and has the ability of rapid response and efficient energy storage. Through the control system, the battery can quickly switch to discharge mode when needed, or switch to charging mode when there is excess electric energy, thereby realizing effective management and deployment of energy. This energy management strategy not only improves the operating efficiency and stability of the water electrolysis hydrogen production system, but also avoids the system shutdown or inefficiency caused by unstable ocean current energy.

[0076] The innovation of the present invention lies in that the energy recovery device designed for the seawater desalination system recovers energy from the high-pressure concentrated brine discharged during the seawater desalination process, thereby significantly reducing the specific energy consumption of fresh water production, bringing higher energy recovery efficiency and more energy-saving and environmentally friendly benefits than traditional reverse osmosis systems.

[0077] The innovation of the present invention lies in the collaborative processing method of exchanging resources between the seawater desalination system and the water electrolysis hydrogen production system through an exchange system, which brings the beneficial effects of efficient power supply to the operation of the seawater desalination system and high-purity fresh water supply to the water electrolysis hydrogen production system, thereby realizing the advantage of efficient utilization of resources.

[0078] The entire system is installed on an offshore floating platform and is suitable for comprehensive energy supply in remote islands and deep sea areas.

[0079] The above embodiments are only preferred embodiments of the present invention and are not intended to limit the protection scope of the present invention. Therefore, any equivalent changes made based on the structure, shape, and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A fresh water-hydrogen integrated supply system based on ocean current energy, characterized in that: It includes a direct-drive transmission system, a seawater desalination system, a water electrolysis hydrogen production system and an exchange system; the direct-drive transmission system is a power supply and transmission system in the fresh water-hydrogen integrated supply system, the seawater desalination system is a system for preparing fresh water from seawater in the fresh water-hydrogen integrated supply system, the water electrolysis hydrogen production system is a system for preparing hydrogen from water by electrolysis in the fresh water-hydrogen integrated supply system, and the exchange system is a system for exchanging resources between the seawater desalination system and the water electrolysis hydrogen production system; The input end of the direct-drive transmission system is connected to an impeller (1), and the output end of the direct-drive transmission system is respectively connected to a seawater desalination system and a water electrolysis hydrogen production system; the direct-drive transmission system converts kinetic energy of seawater into electrical energy, and supplies the electrical energy to the water electrolysis hydrogen production system; a portion of hydrogen produced by the water electrolysis hydrogen production system is processed by an exchange system and used for power supply of the seawater desalination system, and another portion is used for industrial production or as energy storage fuel; the direct-drive transmission system transports the extracted seawater to the seawater desalination system; a portion of fresh water produced by the seawater desalination system is processed by an exchange system and used for hydrogen production by the water electrolysis hydrogen production system, and another portion is used for domestic water.

2. The fresh water-hydrogen integrated supply system based on ocean current energy according to claim 1 is characterized in that: The direct drive transmission system comprises a generator (2), a speed increasing box (3), a speed encoder (4), an electromagnetic clutch (5) and a seawater pump (6); one end of the transmission shaft of the impeller (1) is connected to the blades, the other end of the transmission shaft of the impeller (1) is transmission-connected to one end of the transmission shaft of the generator (2), the other end of the transmission shaft of the generator (2) is transmission-connected to the input shaft of the speed increasing box (3), the power output end of the generator (2) is connected to the water electrolysis hydrogen production system, the output shaft of the speed increasing box (3) is coaxially transmission-connected to the speed encoder (4), the electromagnetic clutch (5) and the transmission end of the seawater pump (6) in sequence, and the outlet of the seawater pump (6) is connected to the seawater desalination system.

3. The fresh water-hydrogen integrated supply system based on ocean current energy according to claim 1 is characterized in that: The seawater desalination system comprises a flushing pump (7), a pressure gauge (8), a flow meter (9), an energy recovery device (11), a reverse osmosis element (12), an accumulator (18) and four solenoid valves (10); the flushing pump (7) is arranged below the energy recovery device (11), the reverse osmosis element (12) and the accumulator (18) are both arranged above the energy recovery device (11), the reverse osmosis element (12) is arranged in front of the accumulator (18), the pressure gauge (8) and the flow meter (9) are arranged on the left and right sides of the energy recovery device (11), and the four solenoid valves (10) are arranged at the fresh water outlet and the outlet of the reverse osmosis element (12) respectively. The concentrated brine outlet and the permeate outlet and energy recovery outlet of the flushing pump (7), the inlet of the flushing pump (7) is connected to the outlet of the seawater pump (6) of the direct drive transmission system, the permeate outlet, energy recovery outlet and flow outlet of the flushing pump (7) are respectively connected to the inlet of the reverse osmosis element (12), the energy recovery device (11) and the inlet of the flow meter (9), the outlet of the flow meter (9) is connected to the inlet of the pressure gauge (8), the fresh water outlet of the reverse osmosis element (12) is respectively connected to the exchange system and the water storage tank, the concentrated brine outlet of the reverse osmosis element (12) is respectively connected to the energy recovery device (11) and the wastewater tank, and the energy recovery device (11) is also connected to the accumulator (18); The energy recovery device (11) comprises a booster cylinder 1 (13), a booster cylinder 2 (14), a piston rod (15), a proximity switch 1 (16) and a proximity switch 2 (17); one end of the booster cylinder 1 (13) is connected to one end of the booster cylinder 2 (14), a distributor is arranged in the middle of the connection position, the cavity of the booster cylinder 1 (13) and the cavity of the booster cylinder 2 (14) are connected through the piston rod (15), and the other end of the booster cylinder 1 (13) is respectively connected to the reverse osmosis element (12) and the piston rod (15). The other end of the booster cylinder (14) is connected to the reverse osmosis element (12) and the flushing pump (7), respectively; the proximity switch (16) is arranged at the other end of the booster cylinder (13); the proximity switch (17) is arranged at the other end of the booster cylinder (14); the concentrated brine outlet of the reverse osmosis element (12) is connected to the inlet (1) of the distributor or the inlet (2) of the distributor; and the accumulator (18) is connected to the other end of the booster cylinder (13) and the other end of the booster cylinder (14).

4. The fresh water-hydrogen integrated supply system based on ocean current energy according to claim 2 is characterized in that: The water electrolysis hydrogen production system comprises a storage battery, a power conversion device, a water electrolysis hydrogen production device, a hydrogen processing device and a hydrogen detection device; the water electrolysis hydrogen production device comprises a PEM electrolyzer and a hydrogen transmitter; the hydrogen processing device comprises a hydrogen dryer and a gas-water separator; the hydrogen detection device comprises a hydrogen flow meter and a purity analyzer; the power output end of the generator (2) of the direct drive transmission system is respectively connected to the input end of the storage battery and the input end of the power conversion device, and the input end of the power conversion device is also connected to the output end of the storage battery. The output end is connected, the raw material port of the PEM electrolyzer of the water electrolysis hydrogen production equipment is connected to the exchange system, the power port of the PEM electrolyzer is connected to the output end of the power conversion equipment, the hydrogen output port of the PEM electrolyzer is connected to the input end of the hydrogen transmitter, the gas-water separator of the hydrogen processing equipment is respectively connected to the output end of the hydrogen transmitter and the input end of the hydrogen dryer, the hydrogen flowmeter is respectively connected to the output end of the hydrogen dryer and the input end of the purity analyzer, and the output end of the purity analyzer is respectively connected to the exchange system and the hydrogen tank.

5. A fresh water-hydrogen integrated supply system based on ocean current energy according to claim 4, characterized in that: The exchange system comprises a fresh water deionization tank and a hydrogen processing station; the fresh water deionization tank deionizes fresh water prepared by the seawater desalination system for use in the electrolytic water hydrogen production system, and the hydrogen processing station processes the hydrogen prepared by the electrolytic water hydrogen production system and converts it into electrical energy for use in the seawater desalination system; the inlet of the fresh water deionization tank is connected to the outlet of the reverse osmosis element (12) of the seawater desalination system, and the outlet of the fresh water deionization tank is connected to the raw material port of the PEM electrolyzer of the electrolytic water hydrogen production system; the inlet of the hydrogen processing station is connected to the output end of the purity analyzer of the electrolytic water hydrogen production system, and the outlet of the hydrogen processing station is connected to the accumulator (19); The integrated fresh water-hydrogen supply system based on ocean current energy also includes a control system; the control system is respectively connected to the direct drive transmission system, the seawater desalination system and the water electrolysis hydrogen production system.

6. The energy recovery method of the fresh water-hydrogen integrated supply system based on ocean current energy according to any one of claims 1 to 5, characterized in that: The electromagnetic valve (10) at the concentrated brine outlet of the reverse osmosis element (12) controls the inlet of the distributor of the energy recovery device (11) to connect with the concentrated brine outlet of the reverse osmosis element (12); when the inlet 1 of the distributor is connected with the concentrated brine outlet of the reverse osmosis element (12), it is in the leftward movement mode; when the inlet 2 of the distributor is connected with the concentrated brine outlet of the reverse osmosis element (12), it is in the rightward movement mode; when the two ends of the piston rod (15) contact the proximity switch 1 (16) and the proximity switch 2 (17) respectively, the electromagnetic valve (10) at the concentrated brine outlet is triggered to switch the inlet of the distributor and change the movement mode; When the solenoid valve (10) at the concentrated brine outlet is switched to the leftward movement mode, the concentrated brine outlet of the reverse osmosis element (12) is connected to the inlet one of the distributor, and the concentrated brine in the concentrated brine outlet of the reverse osmosis element (12) flows into the cavity with the piston rod (15) of the boosting cylinder one (13) through the inlet one of the distributor, pushing the piston rod (15) to move leftward, and the liquid in the cavity without the piston rod (15) of the boosting cylinder one (13) flows into the reverse osmosis element (12). At this time, the solenoid valve (10) at the energy recovery outlet of the flushing pump (7) controls the seawater treated by the flushing pump (7) to flow into the cavity without the piston rod (15) of the boosting cylinder two (14), further pushing the piston rod (15) to move leftward, and the liquid in the cavity with the piston rod (15) of the boosting cylinder two (14) is discharged as waste concentrated brine. When the piston rod (15) moves leftward until it contacts the proximity switch one (16), the solenoid valve (10) at the concentrated brine outlet is switched to the rightward working mode; When the solenoid valve (10) at the concentrated brine outlet is switched to rightward movement, the concentrated brine outlet of the reverse osmosis element (12) is connected to the inlet 2 of the distributor, and the concentrated brine in the concentrated brine outlet of the reverse osmosis element (12) flows into the cavity with the piston rod (15) of the second boosting cylinder (14) through the inlet 2 of the distributor, pushing the piston rod (15) to move rightward. At this time, the solenoid valve (10) at the energy recovery outlet of the flushing pump (7) controls the seawater treated by the flushing pump (7) to flow into the cavity without the piston rod (15) of the first boosting cylinder (13), further pushing the piston rod (15) to move rightward. The liquid in the cavity without the piston rod (15) of the second boosting cylinder (14) flows into the reverse osmosis element (12), and the liquid in the cavity with the piston rod (15) of the first boosting cylinder (13) is discharged as waste concentrated brine. When the piston rod (15) moves rightward until it contacts the second proximity switch (17), the solenoid valve (10) at the concentrated brine outlet is switched to the leftward working mode. The energy generated by the movement of booster cylinder 1 and booster cylinder 2 (14) is transmitted to the accumulator (18) for storage.

7. A method for producing hydrogen from seawater by desalination and electrolysis of water in a freshwater-hydrogen integrated supply system based on ocean current energy according to any one of claims 1 to 5, characterized in that: The impeller (1) drives the seawater pump (6) of the direct drive transmission system to press seawater into the seawater desalination system for desalination; the impeller (1) drives the direct drive transmission system to generate electricity and transmits the electricity to the water electrolysis hydrogen production system for hydrogen production; the seawater desalination system and the water electrolysis hydrogen production system exchange resources through the exchange system; Seawater desalination method: the speed encoder (4) controls the speed of the speed increasing box (3), thereby controlling the amount of seawater pumped by the seawater pump (6); the electromagnetic clutch (5) controls whether the seawater pump (6) is working, thereby controlling whether the seawater desalination system is working; Hydrogen production method by electrolysis of water: PEM electrolyzer produces hydrogen through the coordinated power supply of batteries and power conversion equipment.

8. The method for producing hydrogen from seawater by desalination and electrolysis of water in a freshwater-hydrogen integrated supply system based on ocean current energy according to claim 7, characterized in that: The seawater desalination method is specifically: The flow of seawater drives the impeller (1) to rotate. The rotation of the impeller (1) drives the operation of the seawater pump (6) through the generator (2), the speed increaser (3), the speed encoder (4) and the electromagnetic clutch (5) in sequence. The seawater pump (6) presses the seawater into the flushing pump (7) for flushing. The flushed seawater is transported to the energy recovery device (11). The seawater passing through the energy recovery device (11) is further transported to the reverse osmosis element (12) for osmotic cleaning to produce fresh water. In the working state, when the speed encoder (4) is used to control the speed increaser (3) to increase the speed of the transmission shaft, the speed of the transmission shaft of the seawater pump (6) increases, the amount of seawater extracted increases, the amount of seawater delivered to the flushing pump (7) increases, and then the amount of fresh water produced by osmosis and washing increases by sequentially passing through the energy recovery device (11) and the reverse osmosis unit; when the speed encoder (4) is used to control the speed increaser (3) to reduce the speed of the transmission shaft, the speed of the transmission shaft of the seawater pump (6) decreases, the amount of seawater extracted decreases, the amount of seawater delivered to the flushing pump (7) decreases, and then the amount of fresh water produced by osmosis and washing decreases by sequentially passing through the energy recovery device (11) and the reverse osmosis unit; When fresh water needs to be prepared, the electromagnetic clutch (5) is switched to a working state, and the rotation of the impeller (1) drives the rotation of the seawater pump (6), thereby preparing fresh water through the seawater desalination system; when fresh water does not need to be prepared, the electromagnetic clutch (5) is switched to a non-working state, and the rotation of the impeller (1) cannot drive the seawater pump (6), that is, the seawater desalination system stops preparing fresh water.

9. The method for producing hydrogen from seawater by desalination and electrolysis of water in a freshwater-hydrogen integrated supply system based on ocean current energy according to claim 7, characterized in that: The method for producing hydrogen by electrolysis of water is specifically as follows: The flow of seawater drives the impeller (1) to rotate, and the rotation of the impeller (1) drives the transmission shaft of the generator (2) to rotate, thereby generating electricity, and the generator (2) transmits the electricity to the storage battery and the power conversion device; When the power generated by the direct-drive transmission system driven by seawater is sufficient, part of the power is transmitted to the battery for storage, and the other part of the power is transmitted to the power conversion device. At this time, the battery does not transmit power to the power conversion device; when the seawater flow rate decreases and the power generated by the direct-drive transmission system is insufficient, all the generated power is transmitted to the power conversion device. At this time, the power in the battery transmits power to the power conversion device to maintain the operation of the water electrolysis hydrogen production system; when the direction of seawater changes and the direct-drive transmission system does not generate power, the power in the battery transmits power to the power conversion device to maintain the operation of the water electrolysis hydrogen production system; The power conversion equipment converts AC power into DC power and transmits it to the PEM electrolyzer. The fresh water prepared by the seawater desalination system is deionized and used as the raw water of the PEM electrolyzer. The PEM electrolyzer electrolyzes the deionized fresh water to prepare hydrogen. The prepared hydrogen is transported to the gas-water separator through the hydrogen transmitter. The hydrogen after gas and water separation is transported to the hydrogen dryer. After drying, the hydrogen passes through the hydrogen flowmeter and purity analyzer in turn and is finally stored in the hydrogen tank.

10. The method for producing hydrogen by desalination of seawater and electrolysis of water in a freshwater-hydrogen integrated supply system based on ocean current energy according to claim 7, characterized in that: The resource exchange between the seawater desalination system and the water electrolysis hydrogen production system through the exchange system is specifically as follows: The seawater desalination system transports the prepared fresh water to the fresh water deionization tank of the exchange system for deionization treatment, and the deionized fresh water is transported to the PEM electrolyzer of the water electrolysis hydrogen production system for hydrogen production; the hydrogen prepared by the water electrolysis hydrogen production system is transmitted to the hydrogen processing station of the exchange system for processing and conversion into electrical energy, and the converted electrical energy is transported to the accumulator (18) of the energy recovery device (11) for use by the seawater desalination system.

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