Liquefied air energy storage system, energy storage ship and offshore renewable energy transportation method

Abstract

The application discloses a liquefied air energy storage system, an energy storage ship and a marine renewable energy transportation method. The liquefied air energy storage system comprises an air liquefaction system and a power generation system. The power generation system comprises a liquefied air circulating power generation system, a first working medium circulating power generation system and a second working medium circulating power generation system. The first working medium circulating power generation system and the second working medium circulating power generation system provide part of heat for the liquid air power generation in the power generation process. The energy storage ship comprises the liquefied air energy storage system, provides electric energy for the air liquefaction system and is a marine renewable energy power system. The marine renewable energy transportation method uses the energy storage ship, uses air as an energy carrier, stores marine renewable energy in the form of liquefied air on the ship, and then is transported to the vicinity of the coast to generate power by using the liquefied air. The application can efficiently and at low cost solve the global marine wind power energy storage and transportation problems. The application can greatly reduce the construction and maintenance costs of the offshore power transmission system and is suitable for all marine areas in the world.

Description

Technical Field

[0001] This invention relates to the field of marine energy storage technology, and in particular to a liquefied air energy storage system, an energy storage vessel, and a method for transporting renewable energy at sea. Background Technology

[0002] my country boasts abundant offshore renewable energy resources. Taking wind energy as an example, my country's exploitable offshore wind energy resources reach 2.78 billion kilowatts. As of the end of 2022, my country's cumulative installed capacity of offshore wind power exceeded 30 million kilowatts, and it is projected that the total installed capacity will reach 100 million kilowatts by 2035, at which point the global cumulative installed capacity of offshore wind power will exceed 500 million kilowatts. With the development of near-shore wind energy resources approaching saturation and increasing restrictions on sea use, deep-sea areas have become a new direction for the development of offshore renewable energy. A total of 41 deep-sea offshore wind power clusters have been planned nationwide, with a projected total capacity of 290 million kilowatts, three times the planned capacity for near-shore areas.

[0003] However, the bottleneck restricting the large-scale application of offshore renewable energy such as deep-sea wind power lies in the long-distance transoceanic power transmission, energy storage, and peak shaving issues. Efficient technologies and equipment for offshore wind power "storage" and "transportation" are urgently needed. Currently, domestic near-shore wind power transmits electricity ashore after voltage transformation. However, the high cost and maintenance difficulties of high-power, long-distance transoceanic cable transmission and offshore substation platforms, coupled with a lack of sufficient flexible dispatch capabilities and adequate peak shaving measures, will lead to a decline in the economic viability of wind power. Domestically and internationally, there is vigorous research and development of offshore wind power hydrogen production projects, where hydrogen is produced locally from deep-sea renewable energy, and then the hydrogen or hydrogen-based energy products are transported ashore for power generation or transportation. However, the overall energy utilization efficiency of water electrolysis for hydrogen production, hydrogen storage and transportation, and hydrogen power generation is low. Existing offshore wind power + liquefied air storage (LNG) systems all involve power transmission via cable while simultaneously constructing LNG storage power stations on land. These LNG storage systems require cold storage devices, which are not only extremely costly and difficult to maintain, but also have low overall energy utilization efficiency. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this application provides a liquefied air energy storage system, an energy storage vessel, and a method for transporting renewable energy at sea, in order to solve the technical problems of high cost, difficult maintenance, and low overall energy utilization efficiency in the transportation of renewable energy at sea.

[0005] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0006] A liquefied air energy storage system includes an air liquefaction system and a power generation system. The power generation system includes a liquefied air circulation power generation system, a first working fluid circulation power generation system, and a second working fluid circulation power generation system. The air liquefaction system compresses and cools gaseous air into liquid air, which is then transported to the liquefied air circulation power generation system. In the liquefied air circulation power generation system, the liquid air absorbs heat, expands, and performs work to generate electricity. During the power generation process, the first working fluid circulation power generation system and the second working fluid circulation power generation system each provide a portion of the heat to the liquid air in the liquefied air circulation power generation system.

[0007] In one embodiment, the air liquefaction system includes an air scrubbing tower, an air compressor unit, a first regenerator, a second regenerator, a third regenerator, an air expander, a throttle valve, and a liquefied air storage device. The air scrubbing tower inlet is connected to the atmosphere, and the air scrubbing tower outlet is connected to the air compressor unit inlet.

[0008] The air compressor unit outlet is connected to the hot-side inlet of the first regenerator. The hot-side outlet of the first regenerator is divided into two branches: one branch connects to the hot-side inlet of the second regenerator, and the other branch connects to the inlet of the air expander. The hot-side outlet of the second regenerator is connected to the hot-side inlet of the third regenerator, and the hot-side outlet of the third regenerator is connected to the inlet of the throttle valve. The outlet of the throttle valve is connected to the liquid inlet of the liquefied air storage device. The gas outlet of the liquefied air storage device is connected to the cold-side inlet of the third regenerator. The cold-side outlet of the third regenerator merges with the outlet of the air expander and connects to the cold-side inlet of the second regenerator. The cold-side outlet of the second regenerator is connected to the cold-side inlet of the first regenerator. The cold-side outlet of the first regenerator merges with the outlet of the air scrubber and connects to the inlet of the air compressor unit.

[0009] In one embodiment, the air compressor unit includes a multi-stage compressor with intercooling, the liquefied air storage device includes one or more double-shell vacuum tanks, and the output power of the air expander provides part of the power to the air compressor unit.

[0010] In one embodiment, the liquefied air circulating power generation system includes a liquefied air high-pressure pump, an air vaporizer, an air regenerator, a first seawater heater, a second seawater heater, a first heat source heater, a second heat source heater, a high-pressure air expander, a low-pressure air expander, and a first generator.

[0011] The inlet of the liquefied air high-pressure pump is connected to the liquid inlet of the liquefied air storage device, and the outlet of the liquefied air high-pressure pump is connected to the cold-side inlet of the air vaporizer; the cold-side outlet of the air vaporizer is connected to the cold-side inlet of the air regenerator, and the cold-side outlet of the air regenerator is connected to the cold-side inlet of the first seawater heater; the cold-side outlet of the first seawater heater is connected to the cold-side inlet of the first heat source heater, and the cold-side outlet of the first heat source heater is connected to the inlet of the high-pressure air expander; the outlet of the high-pressure air expander is connected to the cold-side inlet of the second seawater heater, and the cold-side outlet of the second seawater heater is connected to the cold-side inlet of the second heat source heater; the cold-side outlet of the second heat source heater is connected to the inlet of the low-pressure air expander, and the outlet of the low-pressure air expander is directly discharged to the atmosphere; both the high-pressure air expander and the low-pressure air expander are connected to the first generator, which together drive the first generator to rotate and generate electricity.

[0012] In one embodiment, the first working fluid cycle power generation system includes a first working fluid pump, a first working fluid tank, a first working fluid regenerator, a first working fluid expander, a first working fluid vaporizer, a third seawater heater, a third heat source heater, and a second generator; the second working fluid cycle power generation system includes a second working fluid pump, a second working fluid tank, a second working fluid expander, a fourth seawater heater, a fourth heat source heater, and a second generator.

[0013] The inlet of the first working fluid pump is connected to the first working fluid liquid tank, and the outlet of the first working fluid pump is connected to the cold-side inlet of the first working fluid regenerator; the cold-side outlet of the first working fluid regenerator is connected to the cold-side inlet of the first working fluid vaporizer, and the cold-side outlet of the first working fluid vaporizer is connected to the cold-side inlet of the third seawater heater; the cold-side outlet of the third seawater heater is connected to the cold-side inlet of the third heat source heater; the cold-side outlet of the third heat source heater is connected to the inlet of the first working fluid expander, and the outlet of the first working fluid expander is connected to the hot-side inlet of the first working fluid regenerator; the hot-side outlet of the first working fluid regenerator is connected to the hot-side inlet of the air vaporizer, and the hot-side outlet of the air vaporizer is connected to the first working fluid liquid tank.

[0014] The inlet of the second working fluid pump is connected to the second working fluid liquid tank, and the outlet of the second working fluid pump is connected to the cold side inlet of the fourth seawater heater; the cold side outlet of the fourth seawater heater is connected to the cold side inlet of the fourth heat source heater; the cold side outlet of the fourth heat source heater is connected to the inlet of the second working fluid expander, and the outlet of the second working fluid expander is connected to the hot side inlet of the air regenerator; the hot side outlet of the air regenerator is connected to the hot side inlet of the first working fluid vaporizer, and the hot side outlet of the first working fluid vaporizer is connected to the second working fluid liquid tank.

[0015] In one embodiment, the atmospheric saturation temperature of the first working fluid is 10-30°C lower than the vaporization temperature of the high-pressure liquefied air, and the atmospheric saturation temperature of the second working fluid is 10-30°C lower than the vaporization temperature of the high-pressure first working fluid.

[0016] In one embodiment, the first working medium is methane, carbon tetrafluoride, or ethane, and the second working medium is carbon dioxide, propane, or ammonia.

[0017] In one embodiment, the air liquefaction system further includes a compressed air accumulator for storing the heat of compression generated by the air compressor unit, the compressed air accumulator providing heat to the first heat source heater, the second heat source heater, the third heat source heater and the fourth heat source heater.

[0018] This application also provides an energy storage vessel, including the liquefied air energy storage system as described above, wherein the power system providing electricity to the air liquefaction system is a marine renewable energy power system.

[0019] This application also provides a method for transporting renewable energy at sea, using an energy storage vessel as described above, characterized by comprising the following steps:

[0020] The energy storage vessel is transported to the target location of the offshore renewable energy power system. The offshore renewable energy power system is electrically connected to the air liquefaction system on the energy storage vessel to liquefy air on-site for energy storage of the offshore renewable energy. When the air liquefaction system is full of liquefied air, the electrical connection between the offshore renewable energy power system and the air liquefaction system is disconnected, and the vessel fully loaded with liquefied air is transported to the shore. When the ground power is needed, the power generation system on the energy storage vessel is electrically connected to the ground power grid, and the electricity generated by the power generation system is fed into the ground power grid.

[0021] Compared with the prior art, this application has at least the following beneficial effects:

[0022] The liquefied air energy storage system in this application provides some heat to the liquid air in the liquefied air circulation power generation system by setting up a first and second working fluid circulation system, eliminating the need for a cold storage device and improving the overall utilization rate of the liquefied air energy storage system. Moreover, both the first and second working fluids are non-flammable gases, and there are no related harmful substances or CO2 emissions throughout the entire process. The liquefied air energy storage system in this application has the advantages of high safety, non-toxicity, and zero emissions.

[0023] The energy storage vessel and marine renewable energy transportation method described in this application can solve the problems of marine renewable energy and power transmission in a high-efficiency and low-cost manner. It can transport unstable marine renewable energy to the vicinity of the coastline by ship for long-term stable output of reliable, continuous and sufficient quality power. Multiple ships can shuttle back and forth to realize flexible utilization of renewable energy. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the air liquefaction system in an embodiment of this application;

[0025] Figure 2This is a schematic diagram of the power generation system in the embodiments of this application.

[0026] The specific explanations of the reference numerals in the attached drawings are as follows: 1. Air scrubber; 2. Air compressor unit; 3. First regenerator; 4. Air expander; 5. Second regenerator; 6. Third regenerator; 7. Throttling valve; 8. Liquefied air storage device; 9. Compressed air accumulator; 10. Liquefied air high-pressure pump; 11. Air vaporizer; 12. Air regenerator; 13. First seawater heater; 14. First heat source heater; 15. High-pressure air expander; 16. Second seawater heater; 17. Second heat source heater; 18. Low-pressure air expander; 1901. First generator; 1902. Second generator; 20. First working fluid pump; 21. First working fluid regenerator; 22. First working fluid vaporizer; 23. Third seawater heater; 24. Third heat source heater; 25. First working fluid liquid tank; 26. Second working fluid liquid tank; 27. Second working fluid pump; 28. Fourth seawater heater; 29. ​​Fourth heat source heater; 30. Second working fluid expander; 31. Offshore renewable energy power system; 32. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of this invention clearer, the invention is described below with reference to specific embodiments shown in the accompanying drawings. However, it should be understood that these descriptions are merely exemplary and not intended to limit the scope of the invention. Furthermore, descriptions of well-known structures and technologies are omitted in the following description to avoid unnecessarily obscuring the concept of the invention.

[0028] The terminology used in this disclosure is for the purpose of describing particular embodiments only and is not intended to be limiting of the disclosure. The singular forms “a,” “the,” and “the” as used in this disclosure and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the term “and / or” as used herein refers to and includes any and all possible combinations of one or more of the associated listed items.

[0029] It should be understood that although the terms first, second, third, etc., may be used in this disclosure to describe various information, such information should not be limited to these terms and should not be construed as indicating or implying relative importance. These terms are used only to distinguish information of the same type from one another. For example, without departing from the scope of this disclosure, first information may also be referred to as second information, and similarly, second information may also be referred to as first information. Depending on the context, the word "if" as used herein may be interpreted as "when," "when," or "in response to determination."

[0030] In the description of this invention, unless otherwise specified and limited, it should be noted that the terms "installation", "connection" and "linking" should be interpreted broadly. For example, they can refer to mechanical connection or internal connection between two components. They can be direct connection or indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms according to the specific circumstances.

[0031] To better understand the technical solution of the present invention, the present invention will be described in detail below with reference to the accompanying drawings.

[0032] This embodiment provides a liquefied air energy storage system, including an air liquefaction system and a power generation system. The power generation system includes a liquefied air circulation power generation system, a first working fluid circulation power generation system, and a second working fluid circulation power generation system. The air liquefaction system compresses and cools gaseous air into liquid air, which is then transported to the liquefied air circulation power generation system. In the liquefied air circulation power generation system, the liquid air absorbs heat, expands, and performs work to generate electricity. During the power generation process, the first working fluid circulation power generation system and the second working fluid circulation power generation system respectively provide a portion of the heat to the liquid air in the liquefied air circulation power generation system.

[0033] like Figure 1 As shown, the air liquefaction system includes an air scrubbing tower 1, an air compressor unit 2, a first regenerator 3, a second regenerator 5, a third regenerator 6, an air expander 4, a throttle valve 7, and a liquefied air storage device 8.

[0034] The inlet of air scrubber 1 is open to the atmosphere, and the outlet of air scrubber 1 is connected to the inlet of air compressor unit 2. The outlet of air compressor unit 2 is connected to the hot-side inlet of the first regenerator 3. The hot-side outlet of the first regenerator 3 is divided into two streams: one stream is connected to the hot-side inlet of the second regenerator 5, and the other stream is connected to the inlet of the air expander 4. The hot-side outlet of the second regenerator 5 is connected to the hot-side inlet of the third regenerator 6, and the hot-side outlet of the third regenerator 6 is connected to the inlet of the throttle valve 7. The outlet of the throttle valve 7 is connected to the liquid inlet of the liquefied air storage device 8. The gas outlet of the liquefied air storage device 8 is connected to the cold-side inlet of the third regenerator 6. The cold-side outlet of the third regenerator 6 merges with the outlet of the air expander 4 and connects to the cold-side inlet of the second regenerator 5. The cold-side outlet of the second regenerator 5 is connected to the cold-side inlet of the first regenerator 3, and the cold-side outlet of the first regenerator 3 merges with the outlet of air scrubber 1 and connects to the inlet of air compressor unit 2.

[0035] The power system is electrically connected to the air compressor unit 2, providing power to it. In this embodiment, the power system is an offshore renewable energy power system 32. Figure 1As shown, to improve energy efficiency, the air compressor unit 2 in this embodiment includes a multi-stage compressor with intercooling. The air liquefaction system also includes a compressed air heat accumulator 9 to store the heat of compression generated by the air compressor unit 2. The heat storage temperature of the air heat accumulator is in the range of 70-130°C. The heat of compression of the air compressor unit 2 is recovered to the compressed air heat accumulator 9 through heat transfer oil. The heat storage medium of the compressed air heat accumulator 9 is molten salt. To reduce the heat transfer between the liquefied air and the surrounding environment, the liquefied air storage device 8 includes one or more double-shell vacuum tanks. The output power of the air expander 4 provides part of the power to the air compressor unit 2.

[0036] like Figure 2 As shown, the liquefied air circulation power generation system includes a liquefied air high-pressure pump 10, an air vaporizer 11, an air regenerator 12, a first seawater heater 13, a second seawater heater 16, a first heat source heater 14, a second heat source heater 17, a high-pressure air expander 15, a low-pressure air expander 18, and a first generator 1901; the first working fluid circulation power generation system includes a first working fluid pump 20, a first working fluid tank 26, a first working fluid regenerator 21, a first working fluid expander 25, a first working fluid vaporizer 22, a third seawater heater 23, a third heat source heater 24, and a second generator 1902; the second working fluid circulation power generation system includes a second working fluid pump 28, a second working fluid tank 27, a second working fluid expander 31, a fourth seawater heater 29, a fourth heat source heater 30, and a second generator 1902.

[0037] The inlet of the liquefied air high-pressure pump 10 is connected to the liquid inlet of the liquefied air storage device 8, and the outlet of the liquefied air high-pressure pump 10 is connected to the cold-side inlet of the air vaporizer 11; the cold-side outlet of the air vaporizer 11 is connected to the cold-side inlet of the air regenerator 12, and the cold-side outlet of the air regenerator 12 is connected to the cold-side inlet of the first seawater heater 13; the cold-side outlet of the first seawater heater 13 is connected to the cold-side inlet of the first heat source heater 14, and the cold-side outlet of the first heat source heater 14 is connected to the inlet of the high-pressure air expander 15; the outlet of the high-pressure air expander 15 is connected to the cold-side inlet of the second seawater heater 16, and the cold-side outlet of the second seawater heater 16 is connected to the cold-side inlet of the second heat source heater 17; the cold-side outlet of the second heat source heater 17 is connected to the inlet of the low-pressure air expander 18, and the outlet of the low-pressure air expander 18 is directly discharged to the atmosphere; both the high-pressure air expander 15 and the low-pressure air expander 18 are connected to the first generator 1901, which together drive the first generator 1901 to rotate and generate electricity.

[0038] The inlet of the first working fluid pump 20 is connected to the first working fluid liquid tank 26, and the outlet of the first working fluid pump 20 is connected to the cold side inlet of the first working fluid regenerator 21; the cold side outlet of the first working fluid regenerator 21 is connected to the cold side inlet of the first working fluid vaporizer 22, and the cold side outlet of the first working fluid vaporizer 22 is connected to the cold side inlet of the third seawater heater 23; the cold side outlet of the third seawater heater 23 is connected to the cold side inlet of the third heat source heater 24; the cold side outlet of the third heat source heater 24 is connected to the inlet of the first working fluid expander 25, and the outlet of the first working fluid expander 25 is connected to the hot side inlet of the first working fluid regenerator 21; the hot side outlet of the first working fluid regenerator 21 is connected to the hot side inlet of the air vaporizer 11, and the hot side outlet of the air vaporizer 11 is connected to the first working fluid liquid tank 26.

[0039] The inlet of the second working fluid pump 28 is connected to the second working fluid tank 27, and the outlet of the second working fluid pump 28 is connected to the cold side inlet of the fourth seawater heater 29; the cold side outlet of the fourth seawater heater 29 is connected to the cold side inlet of the fourth heat source heater 30; the cold side outlet of the fourth heat source heater 30 is connected to the inlet of the second working fluid expander 31, and the outlet of the second working fluid expander 31 is connected to the hot side inlet of the air regenerator 12; the hot side outlet of the air regenerator 12 is connected to the hot side inlet of the first working fluid vaporizer 22, and the hot side outlet of the first working fluid vaporizer 22 is connected to the second working fluid tank 27.

[0040] In this system, the working fluid at the hot side outlet of the air vaporizer 11 is a saturated or subcooled liquid, and the working fluid at the hot side outlet of the first working fluid vaporizer 22 is also a saturated or subcooled liquid. In order to fully utilize the cold energy of liquefied air in the power generation system, reduce the heat exchange temperature difference, and improve power generation efficiency, the atmospheric pressure saturation temperature of the first working fluid is 10-30°C lower than the high-pressure liquefied air vaporization temperature, and the atmospheric pressure saturation temperature of the second working fluid is 10-30°C lower than the high-pressure first working fluid vaporization temperature. Furthermore, to ensure the safety and environmental protection of the power generation system, in this embodiment, the first working fluid is methane, carbon tetrafluoride (CF4), or ethane, and the working fluid used in the second working fluid cycle power generation system is carbon dioxide, propane, or ammonia. The high-pressure liquefied air vaporization temperature refers to the vaporization temperature of liquefied air at a pressure of 32-36 bar, and the high-pressure first working fluid vaporization temperature refers to the vaporization temperature of the first working fluid at a pressure of 25-35 bar. The working fluid on the heat side of the first heat source heater 14, the second heat source heater 17, the third heat source heater 24 and the fourth heat source heater 30 is water or heat transfer oil, and the heat of the four heat source heaters comes from the compressed air accumulator 9.

[0041] In order to facilitate frequency regulation of the generator in the power generation system, the first working fluid expander 25 and the second working fluid expander 31 jointly drive the same second generator 1902 to rotate and generate electricity.

[0042] The working process of the liquefied air energy storage system in this embodiment is as follows:

[0043] After impurities are removed by the air scrubber 1, the air enters the air compressor unit 2 and is pressurized to a certain pressure. It then enters the first regenerator 3 for initial cooling and is divided into two streams. One stream enters the air expander 4 to form low-temperature, low-pressure air, while the other stream enters the second regenerator 5 for deep cooling. After entering the third regenerator 6, it forms a gas-liquid two-phase air. After passing through the throttle valve 7, it forms a low-temperature, low-pressure gas-liquid two-phase air and enters the liquefied air storage device 8. The low-temperature air at the outlet of the liquefied air storage device 8 enters the third regenerator 6 for heating and mixes with the air expander 4 to form low-temperature, low-pressure air. It then enters the second regenerator 5 for heating and then enters the first regenerator 3 for further heating before merging with the air at the outlet of the air scrubber 1. Finally, it enters the air compressor unit 2 for pressurization, thus forming a complete cycle. The marine renewable energy is stored in the form of liquefied air in the liquefied air storage device 8 on the ship. The compression heat generated by the air compressor unit 2 is stored in the compressed air heat accumulator 9 through heat transfer oil circulation.

[0044] The liquefied air in the liquefied air storage device 8 is pressurized by the liquefied air high-pressure pump 10 and then enters the air vaporizer 11 to become low-temperature high-pressure air. It then enters the air regenerator 12 for further heating, and then enters the first seawater heater 13 to be heated to room temperature. Next, it enters the first heat source heater 14 to form high-pressure air at 60-120°C, and then directly enters the high-pressure air expander 15 to drive the first generator 1901 to generate electricity. The medium-pressure air from the outlet of the high-pressure air expander 15 is heated to room temperature by the second seawater heater 16 and then enters the second heat source for heating. The device 17 generates medium-pressure air at 60-120℃, which then directly enters the low-pressure air expander 18 to drive the first generator 1901 to generate electricity. The air at the outlet of the low-pressure air expander 18 is directly released into the atmosphere. In the first working fluid circulation power generation system, the first working fluid in the first working fluid tank 26 is pressurized by the first working fluid pump 20 to form a high-pressure cryogenic liquid. It then enters the first working fluid regenerator 21 for further heating and enters the first working fluid vaporizer 22 to form a high-pressure cryogenic gas. After being heated to room temperature by the third seawater heater 23, it enters the third heat source heater. Heater 24 generates high-pressure gas at 60-120°C, which then enters the first working fluid expander 25 to drive the second generator 1902 to generate electricity. The low-pressure, low-temperature gas generated at the outlet of the first working fluid expander 25 first passes through the first working fluid regenerator 21 for preliminary cooling, and then enters the air vaporizer 11 to be condensed into a saturated or subcooled liquid state before entering the first working fluid tank 26, thus forming a closed loop. In the second working fluid circulation power generation system, the second working fluid in the second working fluid tank 27 is pressurized by the second working fluid pump 28 to form a high-pressure, low-temperature liquid, which then passes through the fourth... The seawater heater 29 heats the gas to room temperature and then it enters the fourth heat source heater 30 to form a high-pressure gas of 60-120°C. Finally, it enters the second working fluid expander 31 to drive the second generator 1902 to generate electricity. The low-pressure, low-temperature gas formed at the outlet of the second working fluid expander 31 first passes through the air regenerator 12 for preliminary cooling, and then enters the first working fluid vaporizer 22 to be condensed into a saturated or supercooled liquid state before entering the second working fluid liquid tank 27, thus forming a closed loop. The power generation system is electrically connected to the ground power grid, and the electricity generated by the power generation system is incorporated into the ground power grid.

[0045] This embodiment also provides an energy storage ship, including the above-mentioned liquefied air energy storage system. All the equipment in the liquefied air energy storage system is integrated into the hull and the upper deck. The power system that provides power to the air compressor unit 2 is a marine renewable energy power system. Marine renewable energy includes tidal energy, mechanical energy caused by waves, thermal energy, wind energy, solar energy on the sea surface, and biomass energy in the sea.

[0046] In this embodiment, the heat exchangers on the energy storage vessel are all small-sized plate heat exchangers, so that the liquefied air energy storage system can be installed in the confined space of the vessel. During the voyage, the power for the azimuth propulsion system of the energy storage vessel comes from the power generation system on the vessel, enabling the vessel to transport goods without the need for additional energy or the generation of greenhouse gases.

[0047] This embodiment also provides a method for transporting renewable energy by sea, including the following steps:

[0048] The aforementioned energy storage vessel is transported to the offshore renewable energy power system 32 at the target location. The offshore renewable energy power system 32 is electrically connected to the air liquefaction system on the energy storage vessel to liquefy air on-site for energy storage of offshore renewable energy. When the liquefied air storage device 8 is full of liquefied air, the electrical connection between the offshore renewable energy power system and the air liquefaction system is disconnected. The vessel, fully loaded with liquefied air, is transported to the shore. When ground power is needed, the power generation system on the energy storage vessel is electrically connected to the ground power grid, and the electricity generated by the power generation system is fed into the ground power grid.

[0049] 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 can still be made to the specific implementation of the invention or equivalent substitutions can be made to some technical features without departing from the spirit of the technical solutions of the present invention, and all such modifications and substitutions should be covered within the scope of the technical solutions claimed in the present invention.

Claims

1. A liquefied air energy storage system, characterized in that, The system includes an air liquefaction system and a power generation system. The power generation system includes a liquefied air circulation power generation system, a first working fluid circulation power generation system, and a second working fluid circulation power generation system. The air liquefaction system compresses and cools gaseous air into liquid air. The liquid air is then transported to the liquefied air circulation power generation system. In the liquefied air circulation power generation system, the liquid air absorbs heat, expands, and performs work to generate electricity. The first working fluid circulation power generation system and the second working fluid circulation power generation system each provide a portion of the heat to the liquid air in the liquefied air circulation power generation system during the power generation process. The air liquefaction system includes an air scrubbing tower, an air compressor unit, a first regenerator, a second regenerator, a third regenerator, an air expander, a throttle valve, and a liquefied air storage device. The air scrubbing tower inlet is connected to the atmosphere, and the air scrubbing tower outlet is connected to the air compressor unit inlet. The air compressor unit outlet is connected to the hot-side inlet of the first regenerator. The hot-side outlet of the first regenerator is divided into two branches: one branch connects to the hot-side inlet of the second regenerator, and the other branch connects to the inlet of the air expander. The hot-side outlet of the second regenerator is connected to the hot-side inlet of the third regenerator, and the hot-side outlet of the third regenerator is connected to the inlet of the throttle valve. The outlet of the throttle valve is connected to the liquid inlet of the liquefied air storage device. The gas outlet of the liquefied air storage device is connected to the cold-side inlet of the third regenerator. The cold-side outlet of the third regenerator merges with the outlet of the air expander and connects to the cold-side inlet of the second regenerator. The cold-side outlet of the second regenerator is connected to the cold-side inlet of the first regenerator, and the cold-side outlet of the first regenerator merges with the outlet of the air scrubber and connects to the inlet of the air compressor unit. The liquefied air circulating power generation system includes a liquefied air high-pressure pump, an air vaporizer, an air regenerator, a first seawater heater, a second seawater heater, a first heat source heater, a second heat source heater, a high-pressure air expander, a low-pressure air expander, and a first generator. The inlet of the liquefied air high-pressure pump is connected to the liquid inlet of the liquefied air storage device, and the outlet of the liquefied air high-pressure pump is connected to the cold-side inlet of the air vaporizer; the cold-side outlet of the air vaporizer is connected to the cold-side inlet of the air regenerator, and the cold-side outlet of the air regenerator is connected to the cold-side inlet of the first seawater heater; the cold-side outlet of the first seawater heater is connected to the cold-side inlet of the first heat source heater, and the cold-side outlet of the first heat source heater is connected to the inlet of the high-pressure air expander; the outlet of the high-pressure air expander is connected to the cold-side inlet of the second seawater heater, and the cold-side outlet of the second seawater heater is connected to the cold-side inlet of the second heat source heater; the cold-side outlet of the second heat source heater is connected to the inlet of the low-pressure air expander, and the outlet of the low-pressure air expander is directly discharged to the atmosphere; both the high-pressure air expander and the low-pressure air expander are connected to the first generator, which together drive the first generator to rotate and generate electricity; The first working fluid cycle power generation system includes a first working fluid pump, a first working fluid liquid tank, a first working fluid regenerator, a first working fluid expander, a first working fluid vaporizer, a third seawater heater, a third heat source heater, and a second generator; the second working fluid cycle power generation system includes a second working fluid pump, a second working fluid liquid tank, a second working fluid expander, a fourth seawater heater, a fourth heat source heater, and a second generator. The inlet of the first working fluid pump is connected to the first working fluid liquid tank, and the outlet of the first working fluid pump is connected to the cold-side inlet of the first working fluid regenerator; the cold-side outlet of the first working fluid regenerator is connected to the cold-side inlet of the first working fluid vaporizer, and the cold-side outlet of the first working fluid vaporizer is connected to the cold-side inlet of the third seawater heater; the cold-side outlet of the third seawater heater is connected to the cold-side inlet of the third heat source heater; the cold-side outlet of the third heat source heater is connected to the inlet of the first working fluid expander, and the outlet of the first working fluid expander is connected to the hot-side inlet of the first working fluid regenerator; the hot-side outlet of the first working fluid regenerator is connected to the hot-side inlet of the air vaporizer, and the hot-side outlet of the air vaporizer is connected to the first working fluid liquid tank. The inlet of the second working fluid pump is connected to the second working fluid liquid tank, and the outlet of the second working fluid pump is connected to the cold side inlet of the fourth seawater heater; the cold side outlet of the fourth seawater heater is connected to the cold side inlet of the fourth heat source heater; the cold side outlet of the fourth heat source heater is connected to the inlet of the second working fluid expander, and the outlet of the second working fluid expander is connected to the hot side inlet of the air regenerator; the hot side outlet of the air regenerator is connected to the hot side inlet of the first working fluid vaporizer, and the hot side outlet of the first working fluid vaporizer is connected to the second working fluid liquid tank.

2. The liquefied air energy storage system according to claim 1, characterized in that, The air compressor unit includes a multi-stage compressor with intercooling, the liquefied air storage device includes one or more double-shell vacuum storage tanks, and the output power of the air expander provides part of the power to the air compressor unit.

3. The liquefied air energy storage system according to claim 1, characterized in that, The atmospheric saturation temperature of the first working fluid is 10-30℃ lower than the vaporization temperature of high-pressure liquefied air, and the atmospheric saturation temperature of the second working fluid is 10-30℃ lower than the vaporization temperature of the first working fluid under high pressure.

4. The liquefied air energy storage system according to claim 3, characterized in that, The first working medium is methane, carbon tetrafluoride, or ethane, and the second working medium is carbon dioxide, propane, or ammonia.

5. The liquefied air energy storage system according to claim 1, characterized in that, The air liquefaction system also includes a compressed air heat accumulator for storing the compressed heat generated by the air compressor unit, the compressed air heat accumulator providing heat to the first heat source heater, the second heat source heater, the third heat source heater and the fourth heat source heater.

6. An energy storage vessel, characterized in that, Including the liquefied air energy storage system as described in any one of claims 1-5, the power system providing electricity to the air liquefaction system is an offshore renewable energy power system.

7. A method for transporting renewable energy at sea, employing the energy storage vessel as described in claim 6, characterized in that, Includes the following steps: The energy storage vessel is transported to the target location of the offshore renewable energy power system. The offshore renewable energy power system is electrically connected to the air liquefaction system on the energy storage vessel to liquefy air on-site for energy storage of the offshore renewable energy. When the air liquefaction system is full of liquefied air, the electrical connection between the offshore renewable energy power system and the air liquefaction system is disconnected, and the vessel fully loaded with liquefied air is transported to the shore. When the ground power is needed, the power generation system on the energy storage vessel is electrically connected to the ground power grid, and the electricity generated by the power generation system is fed into the ground power grid.

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