Solar heat storage enhanced ocean temperature difference energy water and electricity cogeneration system and method

Abstract

The invention provides a solar heat storage enhanced ocean temperature difference energy water and electricity co-production system and method, and belongs to the technical field of ocean renewable energy sources and energy storage. The solar heat storage enhanced ocean temperature difference energy water and electricity co-production system comprises an offshore wind plant, a solar heating fused salt heat storage unit and a mixed type temperature difference energy water and electricity co-production unit; the solar heating fused salt heat storage unit comprises a warm seawater pump, a photovoltaic and photo-thermal integrated system PV / T, a fused salt heater, a hot fused salt storage tank, a cold fused salt storage tank and a fused salt heat exchanger; the mixed type temperature difference energy water and electricity cogeneration unit comprises an open type circulation part and a closed type circulation part. The solar heat storage enhanced ocean temperature difference energy water and electricity cogeneration system and method aim at achieving cooperative and efficient utilization of offshore wind energy, solar energy and ocean temperature difference energy.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of ocean renewable energy and energy storage technology, in particular to a solar heat storage enhanced ocean temperature difference energy combined water and electricity generation system and method. BACKGROUND

[0002] Currently, offshore wind power and solar photovoltaic as the main renewable energy technology are developing rapidly, but are plagued by intermittency and volatility. The unstable output characteristics of the above two technologies pose a challenge to power grid consumption, and often lead to "abandoned wind and light" due to the inability to be consumed in time. At the same time, ocean temperature difference energy, as a kind of ocean energy with huge reserves and stable output, has not yet been commercialized on a large scale due to its low technical maturity, huge initial investment and low energy conversion efficiency. Among them, the high energy consumption of the pumping equipment that provides power for the system is one of the key bottlenecks restricting its economy. In the prior art, the above three energy systems are mostly developed and operated independently, which has problems such as low utilization efficiency of sea area resources, repeated construction of infrastructure, and limited ability of single system to cope with its inherent defects. Therefore, an innovative solution is urgently needed to integrate the advantages of different energies and achieve the stabilization of energy output and the maximization of system benefits through multi-energy complementation.

[0003] Ocean renewable energy has abundant reserves, and the development and utilization of ocean renewable energy can replace fossil energy and reduce environmental pollution. The temperature difference between the surface seawater and the deep seawater of the ocean contains a large amount of heat energy, which is called ocean temperature difference energy. The thermodynamic cycle using seawater as the working medium can effectively convert the temperature difference energy into electric energy while producing fresh water. However, the temperature difference energy conversion system is limited by low temperature difference, and the power generation efficiency is low.

[0004] Solar energy can heat the warm seawater, effectively increase the temperature difference between the cold and warm seawater, and improve the system efficiency. At the same time, solar energy and wind turbine power generation can supplement the electricity consumption of the control valve and pump components of the system. A molten salt heat storage system is used to recover excess heat, store excess heat during the day, and release heat at night to heat the warm seawater.

[0005] In the prior art, such as patent publication No. CN118791076A, the name is molten salt heat storage system coupled with ocean temperature difference power generation and supercritical seawater desalination device. The molten salt is heated by a solar heat collector to store heat, a closed cycle system uses temperature difference to generate electricity, and a supercritical seawater desalination system desalts seawater.

[0006] The prior art has the following technical problems: the existing ocean temperature difference energy power generation technology utilizes the temperature difference between deep seawater and shallow seawater to generate power, the temperature difference heat gradient is small, and the power generation efficiency is low; the existing ocean temperature difference energy power generation technology is combined with solar energy, and the solar energy is used to heat the warm seawater, but the solar energy heating system is significantly affected by day and night and weather, and the intermittent heat production; the existing ocean temperature difference power generation technology mostly adopts a closed Rankine cycle, and can only generate electricity. The present application effectively overcomes the technical bottlenecks of intermittent solar energy, low ocean temperature difference energy efficiency and large wind power fluctuation, significantly improves the overall energy utilization efficiency, output power and stability of the system, and realizes the continuous and reliable power and water production. SUMMARY

[0007] The present application aims to provide a solar heat storage enhanced ocean temperature difference energy water and electricity cogeneration system and method, aiming to realize the collaborative and efficient utilization of offshore wind energy, solar energy and ocean temperature difference energy. The system stores the excess solar heat during the day through molten salt heat storage technology, and releases the stored heat at night to drive the temperature difference energy system to operate continuously. The offshore wind farm provides a basic power source for the system, effectively driving the high-power warm seawater pump, cold seawater pump and molten salt pump, ensuring the energy supply of the whole system and ensuring the efficiency of the temperature difference energy system water and electricity cogeneration.

[0008] To achieve the above purpose, the present application provides a solar heat storage enhanced ocean temperature difference energy water and electricity cogeneration system, comprising a solar heating and molten salt heat storage unit, a mixed temperature difference energy water and electricity cogeneration unit; The solar heating and molten salt heat storage system comprises a warm seawater pump, a photovoltaic-thermal integrated system PV / T, a molten salt heater, a hot molten salt storage tank, a cold molten salt storage tank and a molten salt heat exchanger. The warm seawater pump sends warm seawater to the PV / T, which heats the warm seawater when the sunlight is sufficient. When the warm seawater is heated above the set temperature, the first one-way valve opens, and part of the warm seawater enters the molten salt heater. The molten salt heater is connected with the hot molten salt storage tank and the cold molten salt storage tank respectively. The cold molten salt is sent from the cold molten salt storage tank to the molten salt heater, and the cold molten salt is heated by the warm seawater, and becomes hot molten salt after heating, and enters the hot molten salt storage tank. When the sunlight is insufficient, the PV / T cannot continue to heat the warm seawater, the second one-way valve opens, and the warm seawater enters the molten salt heat exchanger, and the hot molten salt is sent from the hot molten salt storage tank to the molten salt heat exchanger to heat the warm seawater. The mixed temperature difference energy water and electricity cogeneration unit comprises an open cycle part and a closed cycle part, one end of the open cycle part is connected with the solar heating and molten salt heat storage unit, and the other end of the open cycle part is connected with the closed cycle part.

[0009] Preferably, the open-loop section includes a flash evaporator, one end of which is connected to a warm water pipe of the solar heating and molten salt storage unit. The warm seawater entering the flash evaporator is flashed into water vapor and hot concentrated brine. The water vapor flowing out of the flash evaporator flows to the evaporator installed in the closed loop, and the hot concentrated brine flowing out of the flash evaporator flows to the heat exchanger I installed in the closed loop.

[0010] Preferably, the closed-loop section includes an evaporator, a separator, a first-stage expander, a first-stage generator, a second-stage expander, a second-stage generator, an ejector, a condenser, heat exchanger I, heat exchanger II, and heat exchanger III; Water vapor enters the evaporator and heats the working fluid, which has been preheated in three stages (heat exchanger I, heat exchanger II, and heat exchanger III), into working fluid vapor. The working fluid vapor then enters the separator, where it is separated into working fluid vapor and working fluid liquid. The working fluid vapor is used to drive the first-stage expander and the second expander to do work. After the first and second expanders are started, they are used to drive the first-stage generator and the second generator to generate electricity, respectively. The remaining vapor after separation enters the ejector as the driving fluid, which in turn ejects the working fluid vapor after the first and second expanders have done work. The two are mixed and enter the condenser, where they are condensed into working fluid liquid. The working fluid liquid is then sequentially sent to heat exchangers I, II, and III for preheating before entering the evaporator to begin the next cycle. The working fluid separated from the separator flows to heat exchanger I, the water vapor passing through the evaporator flows to heat exchanger II, and the hot concentrated brine flowing out of the flash evaporator flows to heat exchanger III, all of which are used to heat the working fluid from the condenser. The working fluid separated from the separator flows through heat exchanger III for preheating, and then flows to the condenser to merge with the working fluid flowing out of the ejector and condense again. The steam passing through heat exchanger I flows to the freshwater condenser and is condensed into freshwater, which is then stored in the freshwater collection tank. The hot brine that has passed through heat exchanger I is discharged.

[0011] Preferably, the PV / T is connected to the flash evaporator via a pipeline; a vacuum pump is installed between the molten salt heat exchanger and the flash evaporator, and the vacuum pump first evacuates the open circulation section to a vacuum level before turning on the warm seawater pump to extract warm seawater. A hot molten salt pump is also installed between the hot molten salt storage tank and the molten salt heat exchanger to pump the hot molten salt to the molten salt heat exchanger. A cold molten salt pump is also installed between the cold molten salt storage tank and the molten salt heater to pump the cold molten salt to the molten salt heater for heating.

[0012] Preferably, a first cold seawater pump is provided on one side of the condenser. The first cold seawater pump pumps cold seawater to the condenser for condensation, and the condenser discharges the cold seawater again. A second cold seawater pump is installed on one side of the freshwater condenser. The second cold seawater pump pumps cold seawater to the freshwater condenser for condensation, and the freshwater condenser discharges the cold seawater again. A working fluid pump is installed between the condenser and heat exchanger I to pump the condensed working fluid liquid to heat exchanger I.

[0013] Preferably, a flow sensor and a temperature sensor are provided between the PV / T and the flash evaporator; A flow sensor and a temperature sensor are provided between the separator and the first-stage expander; A flow sensor and a temperature sensor are installed between the first-stage expander and the second-stage expander.

[0014] Preferably, the hot molten salt storage tank and the cold molten salt storage tank are equipped with electric heaters, which are activated when offshore wind power or PV / T generates excess power and there is insufficient heat storage.

[0015] Preferably, in the closed-loop circulation section, the circulating working fluid is a non-azeotropic mixture.

[0016] Preferably, it also includes offshore wind farms and integrated control units; The offshore wind farm includes multiple wind turbines that provide power for solar heating and molten salt thermal storage units, hybrid thermoelectric cogeneration units, and integrated control units; The offshore wind farm, the solar-heated molten salt thermal storage unit, and the hybrid thermoelectric cogeneration unit are all connected to the integrated control system.

[0017] A method for solar thermal energy storage-enhanced ocean thermal energy conversion (OTEC) combined hydropower generation includes the following steps: Photovoltaic power generation, molten salt thermal energy storage, and combined hydropower generation are performed when sunlight is abundant; molten salt thermal energy release and combined hydropower generation are performed when sunlight is insufficient. When there is sufficient sunlight, the molten salt thermal storage process is as follows: the warm seawater pump pumps the warm seawater to the PV / T, the PV / T generates electricity and heats the warm seawater at the same time. When the temperature sensor in front of the flash evaporator exceeds the design point, the first one-way valve opens and the heated warm seawater enters the molten salt heater. The cold molten salt pump pumps the cold molten salt from the cold molten salt storage tank to the molten salt heater. The cold molten salt is heated by the warm seawater into hot molten salt and enters the hot molten salt storage tank. During the daytime molten salt thermal storage process, the integrated control unit prioritizes the use of electricity from offshore wind power and photovoltaic power to drive high-power pump sets; The combined hydropower process: Warm seawater is converted into steam and hot concentrated brine in a flash evaporator under low pressure. The hot concentrated brine enters heat exchanger I, and the steam enters the evaporator through pipes to heat the non-azeotropic working fluid mixture in the evaporator. The non-azeotropic working fluid mixture evaporates into working fluid steam. The non-azeotropic working fluid mixture steam enters the separator. Part of the separated high-pressure working fluid steam enters the drive fluid port of the ejector, and part of the working fluid steam enters the first-stage expander to drive the first-stage expander to work and drive the first-stage generator to generate electricity. When the temperature sensor and pressure sensor are higher than the set value, the third check valve opens and the fourth check valve closes. The working fluid vapor enters the second stage expander to do work and drive the second stage generator to generate electricity. The low-pressure working fluid vapor enters the ejector suction fluid port from the outlet of the second stage expander. When the temperature or pressure sensor value is lower than the set value, the third check valve closes and the fourth check valve opens, driving the working fluid vapor after the first stage expander directly into the ejector. This prevents the low-temperature vapor from condensing and generating water droplets that could damage the blades of the second stage expander, or prevents low-pressure vapor from entering the second stage expander and causing noise and vibration. The low-pressure steam increases in pressure after passing through the ejector and enters the condenser. It is condensed into liquid by the deep cold seawater pumped out by the first cold seawater pump. The liquid is then pumped by the working fluid pump to heat exchanger I to exchange heat with the concentrated brine at the flash evaporator outlet. In heat exchanger II, the steam heated by the evaporator undergoes a second heat exchange. The steam then enters condenser II to be condensed and enters the freshwater collection tank. The working fluid liquid undergoes a third heat exchange in heat exchanger III with the working fluid liquid discharged from the separator. After the three heat exchanges, the working fluid enters the evaporator to continue participating in the cycle. Nighttime molten salt heat release process: The first one-way valve is closed, the second one-way valve is opened, and the molten salt in the hot molten salt tank is pumped by the hot molten salt pump to the molten salt heat exchanger to heat the warm seawater. The heated molten salt enters the cold molten salt tank, and the warm seawater enters the flash evaporator for the combined hydropower process.

[0018] Therefore, the present invention employs the above-mentioned solar thermal storage enhanced ocean thermal energy conversion hydropower system and method, and the technical effects are as follows: This invention employs a PV / T solar collector, which simultaneously generates photovoltaic power and heats warm seawater using solar thermal energy. A molten salt thermal storage system stores excess heat generated by the PV / T during sunny weather, and releases this heat at night and on cloudy days to heat the warm seawater, achieving dynamic control of thermal energy. A hybrid cycle is used, with an open cycle producing desalinated water and a closed cycle generating electricity, achieving combined hydropower. Three heat exchange routes are added to minimize heat loss during the thermodynamic cycle.

[0019] This invention innovatively couples offshore wind energy, solar energy, and ocean thermal energy conversion (OTEC) and introduces them into a molten salt thermal storage system. The offshore wind farm provides the basic power source for this system, effectively driving high-power warm seawater pumps, cold seawater pumps, and molten salt pumps, ensuring the stable operation of the entire system. This design not only effectively overcomes the intermittency and instability of solar power supply but also achieves time-based energy distribution through thermal storage, transferring surplus energy during periods of abundant wind and solar power to nighttime or windless periods for use. This ensures the system can operate stably 24 hours a day without interruption, significantly improving energy utilization efficiency and system output reliability.

[0020] The system employs a hybrid open-loop and closed-loop circulation system. The open-loop section generates steam via a flash evaporator, which heats the working fluid in the closed-loop system; the condensed steam then directly produces fresh water. The closed-loop section utilizes a non-azeotropic working fluid and cascade expansion power generation technology to efficiently convert low-temperature thermal energy into electrical energy. This ingenious structure simultaneously achieves power generation and fresh water production, resulting in significant overall benefits.

[0021] This invention achieves multi-stage, in-depth waste heat recovery within the system. By setting up three heat exchangers, residual heat is recovered from the hot concentrated brine discharged from the flash evaporator, the hot water vapor at the evaporator outlet, and the hot working fluid liquid discharged from the working fluid separator, significantly reducing the system's heat emission losses and thus comprehensively improving the thermodynamic efficiency of the entire system.

[0022] This invention utilizes the stable electricity from offshore wind power as the input to the thermoelectric energy conversion system (TEG) system, ensuring the continuous operation of the system's core energy-consuming equipment and fundamentally guaranteeing the continuity of the TEG subsystem's operation. Simultaneously, surplus electricity generated by wind and solar power can be used for the electric heating of molten salt, achieving efficient conversion and storage of electrical energy into thermal energy, greatly enhancing the self-consumption capacity of renewable energy. Furthermore, the system can share the infrastructure of offshore wind farms, such as submarine cables, grid connection points, and operation and maintenance platforms, significantly reducing the overall investment and operating costs of the project. Attached Figure Description

[0023] Figure 1 This is a flowchart of a solar thermal energy storage enhanced marine thermal energy cogeneration system and method according to the present invention.

[0024] Figure Labels 1. Solar heating and molten salt thermal storage unit; 11. PV / T; 12. Molten salt heater; 13. Hot molten salt storage tank; 14. Cold molten salt storage tank; 15. Molten salt heat exchanger; 101. Warm seawater pump; 102. First check valve; 103. Cold molten salt pump; 104. Second check valve; 105. Hot molten salt pump; 2. Hybrid thermoelectric energy circulation unit; 21. Flash evaporator; 22. Evaporator; 23. Separator; 24. First-stage expander; 25. First-stage generator; 26. Second-stage expander; 27. Second-stage generator; 28. Ejector; 29. ​​Condenser; 210. Heat exchanger I; 211. Heat exchanger II; 212. Heat exchanger III; 213. Freshwater condenser; 214. Freshwater collection tank; 201. First cold seawater pump; 202. Third check valve; 203. Fourth check valve; 204. Working fluid pump; 205. Second cold seawater pump; 3. Fan unit. Detailed Implementation

[0025] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0026] Unless otherwise defined, the technical or scientific terms used in this invention shall have the ordinary meaning as understood by one of ordinary skill in the art to which this invention pertains.

[0027] Example 1 like Figure 1 As shown, a solar thermal energy storage enhanced ocean thermal energy cogeneration system includes a solar heating and molten salt thermal energy storage unit and a hybrid ocean thermal energy cogeneration unit. Solar heating and molten salt thermal storage system, including warm seawater pump, PV / T (solar energy device), molten salt heater, hot molten salt storage tank, cold molten salt storage tank, and molten salt heat exchanger; The warm seawater pump delivers warm seawater to the PV / T to obtain heat from the warm seawater. The PV / T is connected to the molten salt heater through a pipeline and uses the obtained heat to heat the molten salt heater. The molten salt heater is connected to the hot molten salt storage tank and the cold molten salt storage tank respectively. Both the hot molten salt storage tank and the cold molten salt storage tank are connected to the molten salt heat exchanger through pipelines. The hot molten salt storage tank transfers heat to the mixed temperature difference hydropower unit through the molten salt heat exchanger. Afterwards, the warm seawater cools down and flows back to the molten salt heater through the cold molten salt storage tank. The hybrid thermoelectric cogeneration unit includes an open-loop section and a closed-loop section. One end of the open-loop section is connected to a molten salt heat exchanger, and the other end of the open-loop section is connected to the closed-loop section.

[0028] The open-loop section includes a flash evaporator, with an evaporator installed at one end of the flash evaporator. The liquid outlet of the flash evaporator is connected to heat exchanger I, and the other end of the flash evaporator is connected to a molten salt heat exchanger.

[0029] The closed-loop section uses a non-azeotropic mixture as the working fluid. The closed-loop section includes a separator, a first-stage expander, a first-stage generator, a second-stage expander, a second-stage generator, an ejector, a condenser, a first cold seawater pump, a second cold seawater pump, heat exchanger I, heat exchanger II, and heat exchanger III. The evaporator working fluid liquid inlet is connected to heat exchanger II; the evaporator working fluid gas outlet is connected to the separator; the separator liquid outlet is connected to heat exchanger III via a pipeline; the separator gas outlet is connected to the first-stage expander and the ejector drive fluid inlet via a pipeline; the first-stage expander is connected to the first-stage generator; the first-stage expander is connected to the second-stage expander working fluid pipeline; the second-stage expander is connected to the second-stage generator; the second-stage expander is connected to the ejector suction fluid inlet working fluid pipeline; the ejector nozzle is connected to the condenser working fluid inlet working fluid pipeline; the condenser working fluid outlet is connected to heat exchanger I; heat exchanger I is connected to heat exchanger II; heat exchanger II is connected to heat exchanger III; heat exchanger II is connected to the freshwater condenser; and the freshwater condenser is connected to the freshwater collection tank.

[0030] The PV / T and flash evaporator are connected by a pipeline, and a flow sensor and a temperature sensor are installed between the PV / T and the flash evaporator.

[0031] A first check valve is installed between the PV / T and the molten salt heater, a second check valve is installed between the PV / T and the molten salt heat exchanger, a hot molten salt pump is installed between the hot molten salt storage tank and the molten salt heat exchanger, and a second check valve is installed between the cold molten salt storage tank and the molten salt heater.

[0032] The hot molten salt storage tank and the cold molten salt storage tank are equipped with electric heaters. The electric heaters are activated when there is excess power generated by offshore wind power or PV / T and insufficient heat storage. A cold molten salt pump is installed between the cold molten salt tank and the molten salt heat exchanger, and a hot molten salt pump is installed between the hot molten salt tank and the molten salt heater. A warm water pump is installed at the front end of the PV / T.

[0033] It also includes cold seawater pipes and warm seawater pipes; The first cold seawater pump draws seawater through the cold seawater pipe to the condenser inlet. The outside of the cold seawater pipe is equipped with a heat insulation layer. The front ends of both the warm and cold seawater pipes are equipped with filter components. A vacuum pump is installed between the molten salt heat exchanger and the flash evaporator. The vacuum pump first evacuates the open circulation section to a vacuum level, then turns on the warm seawater pump to draw in warm seawater, and the working fluid pump draws the working fluid from the condenser and sends it into heat exchanger I.

[0034] It also includes offshore wind farms and integrated control units; Offshore wind farms include multiple wind turbines near the sea, providing power for solar heating and molten salt thermal storage units, hybrid thermoelectric cogeneration units, and integrated control units; Offshore wind farms, solar-heated molten salt thermal storage units, and hybrid thermoelectric cogeneration units are all connected to an integrated control system.

[0035] A solar thermal energy storage-enhanced ocean thermal energy conversion (OTEC) cogeneration method involves molten salt thermal energy storage and cogeneration during the day, and molten salt thermal energy release and cogeneration at night, comprising the following steps: During the daytime molten salt thermal storage process: The warm seawater pump pumps the warm seawater to the PV / T. The PV / T generates electricity and heats the warm seawater at the same time. When the temperature sensor in front of the flash evaporator exceeds the design point, the first one-way valve opens, and the heated warm seawater enters the molten salt heater. The cold molten salt pump pumps the cold molten salt from the cold molten salt storage tank to the molten salt heater. The cold molten salt is heated by the warm seawater into hot molten salt and enters the hot molten salt storage tank. During the daytime molten salt thermal storage process, the integrated control unit prioritizes the use of offshore wind power to drive high-power pump sets; The combined hydropower process: Warm seawater is converted into steam and hot concentrated brine in a flash evaporator under low pressure. The hot concentrated brine enters heat exchanger I, and the steam enters the evaporator through pipes to heat the non-azeotropic working fluid in the evaporator. The non-azeotropic working fluid evaporates into steam, and the heated steam enters heat exchanger II from the evaporator. The non-azeotropic working fluid steam enters the separator, and part of the separated high-pressure steam enters the drive fluid port of the ejector, while part of the working fluid steam enters the first-stage expander, driving the first-stage expander to work and drive the first-stage generator to generate electricity. When the temperature and pressure sensors exceed the set values, the first check valve opens and the second check valve closes, allowing the working fluid vapor to enter the second-stage expander to perform work and drive the second-stage generator to generate electricity. The low-pressure working fluid vapor enters the ejector suction port from the outlet of the second-stage expander.

[0036] When the temperature or pressure sensor value is lower than the set value, the first check valve closes and the second check valve opens, allowing the working fluid vapor to directly enter the ejector. This prevents the low-temperature vapor from condensing and generating water droplets that could damage the blades of the second-stage expander, or from low-pressure vapor entering the second-stage expander and causing noise and vibration. Low-pressure steam increases in pressure after passing through the ejector and enters the condenser, where it is condensed into liquid by deep cold seawater pumped out by the cold seawater pump. The liquid is then pumped by the working fluid pump to heat exchanger I to exchange heat with the concentrated brine at the flash evaporator outlet. In heat exchanger II, the steam heated by the evaporator undergoes a second heat exchange. The steam then enters condenser II to be condensed and enters the freshwater collection tank. The working fluid liquid undergoes a third heat exchange in heat exchanger III with the working fluid liquid discharged from the separator. After the three heat exchanges, the working fluid enters the evaporator to continue participating in the cycle. Nighttime molten salt heat release process: The first one-way valve is closed, the second one-way valve is opened, and the molten salt in the hot molten salt tank is pumped by the hot molten salt pump to the molten salt heat exchanger to heat the warm seawater. The heated molten salt enters the cold molten salt tank, and the warm seawater enters the flash evaporator for the combined hydropower process.

[0037] Therefore, this invention employs the aforementioned solar thermal storage enhanced marine thermal energy conversion (TEC) hydropower system and method. Through molten salt thermal storage technology, surplus solar heat during the day is stored and released at night to drive the continuous operation of the TEC system. Offshore wind farms provide the basic power source for this system, effectively driving high-power warm seawater pumps, cold seawater pumps, and molten salt pumps, ensuring the energy supply of the entire system and guaranteeing the efficiency of the TEC hydropower conversion.

[0038] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A solar thermal storage enhanced ocean thermal energy conversion hydropower system, characterized in that, This includes solar heating and molten salt thermal storage units, and hybrid thermoelectric combined power generation units; Solar heating and molten salt thermal storage system, including warm seawater pump, photovoltaic / thermal integrated system (PV / T), molten salt heater, hot molten salt storage tank, cold molten salt storage tank, and molten salt heat exchanger; The warm seawater pump delivers warm seawater to the PV / T. When there is sufficient sunlight, the PV / T heats the warm seawater. Once the warm seawater is heated above a set temperature, the first one-way valve opens, and some of the warm seawater enters the molten salt heater. The molten salt heater is connected to both a hot molten salt storage tank and a cold molten salt storage tank. Cold molten salt is sent from the cold molten salt storage tank to the molten salt heater, where it is heated by the warm seawater and becomes hot molten salt, which then enters the hot molten salt storage tank. When sunlight is insufficient, the PV / T cannot continue heating the warm seawater, and the second one-way valve opens, allowing the warm seawater to enter the molten salt heat exchanger. The hot molten salt is then sent from the hot molten salt storage tank to the molten salt heat exchanger to heat the warm seawater. The hybrid thermoelectric cogeneration unit includes an open-loop section and a closed-loop section. One end of the open-loop section is connected to a solar heating and molten salt thermal storage unit, and the other end of the open-loop section is connected to the closed-loop section.

2. The solar thermal storage enhanced ocean thermal energy conversion hydropower system according to claim 1, characterized in that, The open-loop section includes a flash evaporator. One end of the flash evaporator is connected to a warm water pipe of the solar heating and molten salt storage unit. The warm seawater entering the flash evaporator is flashed into water vapor and hot concentrated brine. The water vapor flowing out of the flash evaporator flows to the evaporator installed in the closed loop, and the hot concentrated brine flowing out of the flash evaporator flows to the heat exchanger I installed in the closed loop.

3. The solar thermal storage enhanced ocean thermal energy conversion hydropower system according to claim 1, characterized in that, The closed-loop system includes an evaporator, a separator, a first-stage expander, a first-stage generator, a second-stage expander, a second-stage generator, an ejector, a condenser, heat exchanger I, heat exchanger II, and heat exchanger III. Water vapor enters the evaporator and heats the working fluid, which has been preheated in three stages (heat exchanger I, heat exchanger II, and heat exchanger III), into working fluid vapor. The working fluid vapor then enters the separator, where it is separated into working fluid vapor and working fluid liquid. The working fluid vapor is used to drive the first-stage expander and the second expander to do work. After the first and second expanders are started, they are used to drive the first-stage generator and the second generator to generate electricity, respectively. The remaining vapor after separation enters the ejector as the driving fluid, which in turn ejects the working fluid vapor after the first and second expanders have done work. The two are mixed and enter the condenser, where they are condensed into working fluid liquid. The working fluid liquid is then sequentially sent to heat exchangers I, II, and III for preheating before entering the evaporator to begin the next cycle. The working fluid separated from the separator flows to heat exchanger I, the water vapor passing through the evaporator flows to heat exchanger II, and the hot concentrated brine flowing out of the flash evaporator flows to heat exchanger III, all of which are used to heat the working fluid from the condenser. The working fluid separated from the separator flows through heat exchanger III for preheating, and then flows to the condenser to merge with the working fluid flowing out of the ejector and condense again. The steam passing through heat exchanger I flows to the freshwater condenser and is condensed into freshwater, which is then stored in the freshwater collection tank. The hot brine that has passed through heat exchanger I is discharged.

4. The solar thermal storage enhanced ocean thermal energy conversion hydropower system according to claim 1, characterized in that, The PV / T is connected to the flash evaporator via a pipeline; a vacuum pump is installed between the molten salt heat exchanger and the flash evaporator. The vacuum pump first evacuates the open circulation section to a vacuum level, and then turns on the warm seawater pump to extract warm seawater. A hot molten salt pump is also installed between the hot molten salt storage tank and the molten salt heat exchanger to pump the hot molten salt to the molten salt heat exchanger. A cold molten salt pump is also installed between the cold molten salt storage tank and the molten salt heater to pump the cold molten salt to the molten salt heater for heating.

5. A solar thermal storage enhanced ocean thermal energy conversion hydropower system according to claim 1, characterized in that, A first cold seawater pump is installed on one side of the condenser. The first cold seawater pump sends cold seawater to the condenser for condensation, and the condenser discharges the cold seawater again. A second cold seawater pump is installed on one side of the freshwater condenser. The second cold seawater pump pumps cold seawater to the freshwater condenser for condensation, and the freshwater condenser discharges the cold seawater again. A working fluid pump is installed between the condenser and heat exchanger I to pump the condensed working fluid liquid to heat exchanger I.

6. A solar thermal storage enhanced ocean thermal energy conversion hydropower system according to claim 1, characterized in that, A flow sensor and a temperature sensor are installed between the PV / T and the flash evaporator; A flow sensor and a temperature sensor are provided between the separator and the first-stage expander; A flow sensor and a temperature sensor are installed between the first-stage expander and the second-stage expander.

7. A solar thermal storage enhanced ocean thermal energy conversion hydropower system according to claim 1, characterized in that, The hot molten salt storage tank and the cold molten salt storage tank are equipped with electric heaters, which are activated when offshore wind power or PV / T generates excess power and there is insufficient heat storage.

8. A solar thermal storage enhanced ocean thermal energy conversion hydropower system according to claim 3, characterized in that, In the closed-loop section, the circulating working fluid is a non-azeotropic mixture.

9. A solar thermal storage enhanced ocean thermal energy conversion hydropower system according to claim 1, characterized in that, It also includes offshore wind farms and integrated control units; The offshore wind farm includes multiple wind turbines that provide power for solar heating and molten salt thermal storage units, hybrid thermoelectric cogeneration units, and integrated control units; The offshore wind farm, the solar-heated molten salt thermal storage unit, and the hybrid thermoelectric cogeneration unit are all connected to the integrated control system.

10. A method for solar thermal storage enhanced ocean thermal energy conversion hydropower, implemented using a solar thermal storage enhanced ocean thermal energy conversion hydropower system as described in any one of claims 1-9, characterized in that, Photovoltaic power generation, molten salt thermal storage, and combined hydropower are carried out when there is sufficient sunlight; molten salt thermal release and combined hydropower are carried out when there is insufficient sunlight. The process includes the following steps: When there is sufficient sunlight, the molten salt thermal storage process is as follows: the warm seawater pump pumps the warm seawater to the PV / T, the PV / T generates electricity and heats the warm seawater at the same time. When the temperature sensor in front of the flash evaporator exceeds the design point, the first one-way valve opens and the heated warm seawater enters the molten salt heater. The cold molten salt pump pumps the cold molten salt from the cold molten salt storage tank to the molten salt heater. The cold molten salt is heated by the warm seawater into hot molten salt and enters the hot molten salt storage tank. During the daytime molten salt thermal storage process, the integrated control unit prioritizes the use of electricity from offshore wind power and photovoltaic power to drive high-power pump sets; The combined hydropower process: Warm seawater is transformed into steam and hot concentrated brine in a flash evaporator under low pressure. The hot concentrated brine enters heat exchanger I, and the steam enters the evaporator through pipes to heat the non-azeotropic working fluid mixture in the evaporator. The non-azeotropic working fluid mixture evaporates into working fluid steam, which enters the separator. Part of the separated high-pressure working fluid steam enters the drive fluid port of the ejector, and part of the working fluid steam enters the first-stage expander, driving the first-stage expander to work and driving the first-stage generator to generate electricity. When the temperature sensor and pressure sensor are higher than the set value, the third check valve opens and the fourth check valve closes. The working fluid vapor enters the second stage expander to do work and drive the second stage generator to generate electricity. The low-pressure working fluid vapor enters the ejector suction fluid port from the outlet of the second stage expander. When the temperature or pressure sensor value is lower than the set value, the third check valve closes and the fourth check valve opens, driving the working fluid vapor after the first stage expander directly into the ejector. This prevents the low-temperature vapor from condensing and generating water droplets that could damage the blades of the second stage expander, or prevents low-pressure vapor from entering the second stage expander and causing noise and vibration. The low-pressure steam increases in pressure after passing through the ejector and enters the condenser. It is condensed into liquid by the deep cold seawater pumped out by the first cold seawater pump. The liquid is then pumped by the working fluid pump to heat exchanger I to exchange heat with the concentrated brine at the flash evaporator outlet. In heat exchanger II, the steam heated by the evaporator undergoes a second heat exchange. The steam then enters condenser II to be condensed and enters the freshwater collection tank. The working fluid liquid undergoes a third heat exchange in heat exchanger III with the working fluid liquid discharged from the separator. After the three heat exchanges, the working fluid enters the evaporator to continue participating in the cycle. Nighttime molten salt heat release process: The first one-way valve is closed, the second one-way valve is opened, and the molten salt in the hot molten salt tank is pumped by the hot molten salt pump to the molten salt heat exchanger to heat the warm seawater. The heated molten salt enters the cold molten salt tank, and the warm seawater enters the flash evaporator for the combined hydropower process.

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