Supercritical carbon dioxide energy storage system and method based on porous liquid absorption and storage

Abstract

The invention discloses a supercritical carbon dioxide energy storage system and method based on porous liquid absorption and storage, and belongs to the technical field of energy storage industry. Comprising a low-pressure storage system for storing low-pressure carbon dioxide; the compression energy storage system is used for compressing the carbon dioxide energy storage working medium; the high-pressure storage system is used for obtaining and storing high-pressure supercritical carbon dioxide; the expansion energy release system is used for high-pressure supercritical expansion energy release and pushing a power generator to generate power; and the heat circulation system exchanges heat with and circulates heat with the compression energy storage system and the expansion energy release system. A porous liquid absorbent is adopted. Permanent gaps for containing carbon dioxide can be provided, the problem of a carbon dioxide low-pressure storage end can be solved, and the system investment cost is greatly reduced. High-density storage of the low-voltage end of carbon dioxide is achieved through a chemical absorption method, the supercritical carbon dioxide compression energy storage system stores excess electric quantity generated by the renewable energy system, expansion power generation is carried out in the power utilization peak, and the peak regulation capacity of a power grid is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of energy storage industry, and in particular relates to a supercritical carbon dioxide energy storage system and method based on porous liquid absorption storage. Background Art

[0002] Renewable energy represented by wind and solar energy has obvious disadvantages such as volatility, periodicity and uncertainty, which makes the power grid with high penetration of renewable energy face challenges in energy balance and grid stability. On the one hand, it is necessary to promote the flexibility transformation of thermal power units and improve the peak-shaving capacity of thermal power units. On the other hand, the introduction of energy storage technology is not only an important means to achieve large-scale access to renewable energy generation, but also can improve the overall efficiency, safety and economy of the transmission and distribution side of the power grid.

[0003] Compressed carbon dioxide energy storage technology has many advantages, such as high energy storage density, low economic cost, long operating life, and negative carbon emissions. It is suitable for the construction of large-scale long-term energy storage systems and sustainable development in my country, and has a very broad development prospect. However, the above energy storage method has great limitations. The energy density stored at the low-pressure end is not high enough, and a huge storage space is required. Summary of the invention

[0004] The present invention proposes a supercritical carbon dioxide compression energy storage system based on porous liquid, which realizes high-density storage of carbon dioxide and can effectively overcome the storage defects of the low-pressure end of carbon dioxide.

[0005] The technical solution adopted by the present invention is:

[0006] Supercritical carbon dioxide energy storage system based on porous liquid absorption storage, including

[0007] A low-pressure storage system for storing low-pressure carbon dioxide;

[0008] A compression energy storage system, connected to the low-pressure storage system, is used to compress the carbon dioxide energy storage medium;

[0009] a high-pressure storage system, connected to the compression energy storage system, for obtaining and storing high-pressure supercritical carbon dioxide;

[0010] An expansion energy release system is connected to the high-pressure storage system and is connected to a generator, and is used for high-pressure supercritical expansion energy release and driving the generator to generate electricity;

[0011] The heat circulation system is connected to the compression energy storage system and the expansion energy release system, and the heat circulation system performs heat exchange and heat circulation with the compression energy storage system and the expansion energy release system.

[0012] Energy storage method of supercritical carbon dioxide energy storage system based on porous liquid absorption storage:

[0013] When electricity consumption is low, the absorbent flows out from the outlet of the low-pressure storage tank, and is heated in the first heat exchanger after being adjusted by the throttle valve. The absorbent releases high-temperature low-pressure gas when heated, and flows through the pickling tower to remove volatile ammonia and water. The carbon dioxide gas at the outlet of the pickling tower enters the second heat exchanger for heat exchange, and the outlet low-temperature low-pressure carbon dioxide gas enters the compressor. The excess electricity generated by wind power generation, photovoltaic power generation, and thermal power generation is transmitted to the motor through the circuit. Under the action of the compressor, this part of the excess electricity is converted into the internal energy of low-temperature and high-pressure supercritical carbon dioxide. The low-temperature and high-pressure supercritical carbon dioxide flows out from the compressor outlet and enters the high-pressure storage tank for storage;

[0014] During peak electricity consumption, the low-temperature and high-pressure supercritical carbon dioxide in the high-pressure storage tank enters the cold side inlet of the third heat exchanger after being adjusted by the throttle valve. After heat exchange, high-temperature and high-pressure supercritical carbon dioxide is obtained. The high-temperature and high-pressure supercritical carbon dioxide performs work on the expander. After the high-temperature and high-pressure supercritical expansion work, it becomes high-temperature and low-pressure carbon dioxide and enters the hot side inlet of the fourth heat exchanger. The low-temperature and low-pressure carbon dioxide at the hot side outlet of the fourth heat exchanger enters the absorption tower. The absorbent is stored in the absorption tower after being heated and regenerated in the first heat exchanger to absorb the low-temperature and low-pressure carbon dioxide. The absorbent is stored in the low-pressure storage tank.

[0015] Energy storage method of supercritical carbon dioxide energy storage system based on porous liquid absorption storage:

[0016] When electricity consumption is low, the absorbent flows out from the outlet of the low-pressure storage tank, and is desorbed in the regeneration tower after being adjusted by the throttle valve. The high-temperature low-pressure gas separated from the absorbent enters the first heat exchanger of the heat circulation system from the outlet of the regeneration tower for heat exchange. The outlet low-temperature low-pressure carbon dioxide gas enters the compressor. The excess electricity generated by wind power generation (18), photovoltaic power generation, and thermal power generation is transmitted to the motor through the circuit. Under the action of the compressor, this part of the excess electricity is converted into the internal energy of low-temperature and high-pressure supercritical carbon dioxide. The low-temperature and high-pressure supercritical carbon dioxide flows out from the outlet of the compressor and enters the high-pressure storage tank for storage.

[0017] During peak electricity consumption, the low-temperature and high-pressure supercritical carbon dioxide in the high-pressure storage tank enters the cold side inlet of the second heat exchanger of the thermal cycle system after being adjusted by the throttle valve. After heat exchange, high-temperature and high-pressure supercritical carbon dioxide is obtained. The high-temperature and high-pressure supercritical carbon dioxide performs work on the expander. After the high-temperature and high-pressure supercritical expansion work, it becomes high-temperature and low-pressure carbon dioxide and enters the hot side inlet of the third heat exchanger of the thermal cycle system. The low-temperature and low-pressure carbon dioxide at the hot side outlet of the third heat exchanger enters the low-pressure storage tank, is absorbed by the absorbent and stored.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] The present invention reduces the cost of building a carbon dioxide compression energy storage system, improves the energy conversion efficiency of the energy storage system, and improves energy efficiency and utilization.

[0020] The present invention adopts porous liquid absorbent as absorbent, which can provide permanent space for accommodating carbon dioxide, solve the problem of low-pressure storage end of carbon dioxide, and greatly reduce system investment cost.

[0021] The present invention realizes high-density storage of carbon dioxide at the low-pressure end through chemical absorption. The supercritical carbon dioxide compression energy storage system stores excess electricity generated by the renewable energy system and expands to generate electricity during peak electricity consumption, which helps to improve the peak-shaving capacity of the power grid. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a structural schematic diagram of Embodiment 1 of the present invention;

[0023] Figure 2 It is a structural schematic diagram of Embodiment 2 of the present invention;

[0024] Among them: 1. low-pressure storage tank; 2. throttle valve; 3. first heat exchanger; 4. second heat exchanger; 5. third heat exchanger; 6. fourth heat exchanger; 7. first low-temperature medium storage tank; 8. first high-temperature medium storage tank; 9. second high-temperature medium storage tank; 10. second low-temperature medium storage tank; 11. second circulation pump; 12. first circulation pump; 13. fourth circulation pump; 14. third circulation pump; 15. pickling tower; 16. compressor; 17. motor; 18. photovoltaic power generation device; 19. wind power generation device; 20. thermal power generation device; 21. high-pressure storage tank; 22. throttle valve; 23. expander; 24. generator; 25. power grid; 26. absorption tower; 27. fifth circulation pump; 28. regeneration tower; 29. ​​sixth circulation pump. DETAILED DESCRIPTION

[0025] In order to better understand the purpose, structure and function of the present invention, the present invention is further described in detail below in conjunction with the accompanying drawings.

[0026] The critical point of carbon dioxide (7.39MPa and 31.4℃) is easier to reach than air, and supercritical carbon dioxide has properties such as low viscosity, high density, and good thermal conductivity. As the area with the most concentrated carbon dioxide emissions, the abundant carbon dioxide from thermal power plants can be used as the best stable carbon source for compressed carbon dioxide energy storage systems after capture, realizing the storage and utilization of carbon dioxide, which is conducive to solving the problem of carbon emissions. Relying on thermal power plants to establish a carbon dioxide energy storage system is the best matching way to achieve complementary resource advantages.

[0027] The low-pressure end uses porous liquid as a chemical absorption medium to achieve high-density storage of gas molecules under low pressure, reduce the volume of the storage device, and solve the problem of low-pressure energy storage. According to the changes in the power load, the porous liquid desorbs and releases carbon dioxide, which can be absorbed by the compressor to store the surplus power generated by wind power, photovoltaics and other energy sources at ordinary times, and release and generate electricity when the power grid has high power demand, which can cooperate with thermal power plants to improve the load regulation capacity of the power generation system. During the storage process, chemical reaction energy can be used to utilize waste heat. At the same time, the large amount of waste heat from the flue gas and steam of the thermal power plant can provide sufficient external heat source for the carbon dioxide energy storage system.

[0028] The present invention reduces the cost of building a carbon dioxide compression energy storage system, improves the energy conversion efficiency of the energy storage system, and improves energy efficiency and utilization.

[0029] Embodiment 1:

[0030] like Figure 1 As shown, the present invention provides a supercritical carbon dioxide energy storage system based on porous liquid absorption storage, comprising

[0031] A low-pressure storage system for storing low-pressure carbon dioxide, the low-pressure storage system having a gas inlet and a storage system outlet;

[0032] A compression energy storage system, connected to the low-pressure storage system, is used to compress the carbon dioxide energy storage medium to obtain high-pressure supercritical carbon dioxide. The compression energy storage system includes an energy storage system inlet and a supercritical carbon dioxide outlet;

[0033] A high-pressure storage system, connected to the compressor outlet of the compression energy storage system, for obtaining and storing high-pressure supercritical carbon dioxide, having a storage system inlet and a storage system outlet;

[0034] An expansion energy release system is connected to the high-pressure storage system and is connected to a generator, and is used for high-pressure supercritical expansion energy release and driving the generator to generate electricity, and has an energy release system inlet and an energy release system outlet;

[0035] The heat circulation system is connected to the compression energy storage system and the expansion energy release system, and is distributed in the process of the compression energy storage system and the expansion energy release system. The heat circulation system exchanges heat and circulates heat with the compression energy storage system and the expansion energy release system.

[0036] The low-pressure storage system includes an absorption tower 26, a low-pressure storage tank 1 and a waste heat utilization system;

[0037] The absorption tower 26 has an absorption tower inlet and an absorption tower outlet. The absorption tower 26 inlet is connected to the outlet of the first heat exchanger 3 and the outlet of the fourth heat exchanger 6 respectively. The absorption tower 26 outlet is connected to the low-pressure storage tank 1. The absorption tower 26 is also connected to a waste heat utilization system.

[0038] The low-pressure storage tank 1 is used to store the porous rich liquid of the low-pressure working medium. The outlet of the low-pressure storage tank 1 is connected to the inlet of the first heat exchanger 3.

[0039] The low-pressure storage tank 1 has a storage tank inlet and a storage tank outlet. The inlet of the low-pressure storage tank 1 is connected to the outlet of the absorption tower 26. A throttle valve 2 is installed on the pipeline connecting the outlet of the low-pressure storage tank 1 and the inlet of the first heat exchanger 3.

[0040] The inlet and outlet of the waste heat utilization system are both connected to the absorption tower 26. The low-temperature working fluid obtains the heat released by the chemical reaction inside the absorption tower 26, flows out from the outlet of the waste heat utilization system and is used for energy utilization.

[0041] The waste heat utilization system includes a fifth circulation pump 27 and a heat exchange medium. The outlet of the fifth circulation pump 27 is a low-temperature medium, which is used to obtain the chemical energy released by the reaction between the porous liquid absorbent in the absorption tower 26 and the carbon dioxide gas, and flows out from the outlet of the waste heat utilization system to achieve effective energy utilization.

[0042] The compressed energy storage system includes a throttle valve 2, a first heat exchanger 3, a pickling tower 15, a compressor 16, a motor 17, a photovoltaic power generation device 18, a wind power generation device 19 and a thermal power generation device 20; a throttle valve 2 is installed on the pipeline connecting the outlet of the low-pressure storage tank 1 and the cold side inlet of the first heat exchanger 3, the cold side outlet of the first heat exchanger 3 is respectively connected to the inlet of the pickling tower 15 and the inlet of the absorption tower 26, the hot side inlet and the hot side outlet of the first heat exchanger 3 are connected to the heat circulation system, the outlet of the pickling tower 15 is connected to the hot side inlet of the second heat exchanger 4, the hot side outlet of the second heat exchanger 4 is connected to the inlet of the compressor 16, the outlet of the compressor 16 is connected to the high-pressure storage system, the inlet of the compressor 16 is connected to the outlet of the motor 17 through the abandoned power transmission circuit, and the inlet of the motor 17 is connected to the outlets of the photovoltaic power generation device 18, the wind power generation device 19 and the thermal power generation device 20 through the abandoned power transmission circuit.

[0043] The throttle valve 2 comprises a throttle valve inlet and a throttle valve outlet, wherein the throttle valve inlet is connected to the outlet of the low-pressure storage tank 1, and the throttle valve outlet is connected to the cold side inlet of the first heat exchanger 3;

[0044] The first heat exchanger 3 comprises a hot side inlet, a hot side outlet, a cold side inlet and a cold side outlet, and the cold side inlet of the first heat exchanger 3 is connected to the outlet of the throttle valve 2;

[0045] The high-pressure storage system includes a high-pressure storage tank 21 having a storage tank inlet and a storage tank outlet. The high-pressure storage tank 21 is connected to the outlet of the compressor 16 to obtain low-temperature and high-pressure supercritical carbon dioxide. The outlet of the high-pressure storage tank 21 is connected to the inlet of the third heat exchanger 5.

[0046] The expansion energy release system includes a throttle valve 22, an expander 23 and a generator 24; a throttle valve 22 is installed on the pipeline connecting the outlet of the high-pressure storage tank 21 and the cold side inlet of the third heat exchanger 5, the cold side outlet of the third heat exchanger 5 is connected to the inlet of the expander 23, the outlet of the expander 23 is connected to the hot side inlet of the fourth heat exchanger 6, the expander 23 is also connected to the generator 24, and the outlet of the generator 24 is connected to the power grid 25 through a power transmission line.

[0047] The throttle valve 22 has a throttle valve inlet and a throttle valve outlet, the throttle valve inlet is connected to the outlet of the high-pressure storage tank 21, and the throttle valve outlet is connected to the inlet of the third heat exchanger 5;

[0048] The heat circulation system includes a first heat exchanger 3, a second heat exchanger 4, a third heat exchanger 5, a fourth heat exchanger 6, a first low-temperature medium storage tank 7, a first high-temperature medium storage tank 8, a second high-temperature medium storage tank 9, a second low-temperature medium storage tank 10, a second circulation pump 11, a first circulation pump 12, a fourth circulation pump 13 and a third circulation pump 14;

[0049] The hot side inlet of the first heat exchanger 3 is connected to the outlet of the second circulation pump 11, the hot side outlet of the first heat exchanger 3 is connected to the inlet of the first low-temperature medium storage tank 7, the cold side inlet of the first heat exchanger 3 is connected to the outlet of the low-pressure storage tank 1, and the cold side outlet of the first heat exchanger 3 is connected to the inlet of the pickling tower 15 and the inlet of the absorption tower 26 respectively;

[0050] The hot side inlet of the second heat exchanger 4 is connected to the outlet of the pickling tower 15, the hot side outlet of the second heat exchanger 4 is connected to the inlet of the compressor 16, the cold side inlet of the second heat exchanger 4 is connected to the outlet of the fourth circulating pump 13, and the cold side outlet of the second heat exchanger 4 is connected to the inlet of the second high temperature medium storage tank 9;

[0051] The hot side inlet of the third heat exchanger 5 is connected to the outlet of the third circulation pump 14, the hot side outlet of the third heat exchanger 5 is connected to the inlet of the second low-temperature medium storage tank 10, the cold side inlet of the third heat exchanger 5 is connected to the outlet of the high-pressure storage tank 21, and the cold side outlet of the third heat exchanger 5 is connected to the inlet of the expander 23.

[0052] The hot side inlet of the fourth heat exchanger 6 is connected to the outlet of the expander 23, the hot side outlet of the fourth heat exchanger 6 is connected to the inlet of the absorption tower 26, the cold side inlet of the fourth heat exchanger 6 is connected to the outlet of the first circulation pump 12, and the cold side outlet of the fourth heat exchanger 6 is connected to the inlet of the first high temperature medium storage tank 8;

[0053] The inlet of the first low-temperature medium storage tank 7 is connected to the hot side outlet of the first heat exchanger 3, and the outlet of the first low-temperature medium storage tank 7 is connected to the inlet of the first circulation pump 12;

[0054] The inlet of the first high temperature medium storage tank 8 is connected to the cold side outlet of the fourth heat exchanger 6, and the outlet of the first high temperature medium storage tank 8 is connected to the inlet of the second circulation pump 11;

[0055] The inlet of the second high temperature medium storage tank 9 is connected to the cold side outlet of the second heat exchanger 4 , and the outlet of the second high temperature medium storage tank 9 is connected to the inlet of the third circulation pump 14 .

[0056] The inlet of the second cryogenic medium storage tank 10 is connected to the hot side outlet of the third heat exchanger 5 , and the outlet of the second cryogenic medium storage tank 10 is connected to the inlet of the fourth circulation pump 13 .

[0057] The present invention provides an energy storage method of a supercritical carbon dioxide energy storage system based on porous liquid absorption storage.

[0058] When electricity consumption is low, the porous carbon-rich liquid flows out from the outlet of the low-pressure storage tank 1, is adjusted by the throttle valve 2, and is heated in the first heat exchanger 3. The porous carbon-rich liquid releases high-temperature low-pressure gas when heated, and flows through the pickling tower 15 to remove volatile ammonia and water. The carbon dioxide gas at the outlet of the pickling tower 15 enters the second heat exchanger 4 for heat exchange, and the outlet low-temperature low-pressure carbon dioxide gas enters the compressor 16. The excess electricity generated by the photovoltaic power generation device 18, the wind power generation device 19, the thermal power generation device 20 and other devices is transmitted to the motor 17 through the circuit. Under the action of the compressor 16, this part of the excess electricity is converted into the internal energy of low-temperature and high-pressure supercritical carbon dioxide. The low-temperature and high-pressure supercritical carbon dioxide flows out from the outlet of the compressor 16 and enters the high-pressure storage tank 21 for storage;

[0059] During peak electricity consumption, the low-temperature and high-pressure supercritical carbon dioxide in the high-pressure storage tank 21 is adjusted by the throttle valve 22 and enters the cold side inlet of the third heat exchanger 5. After heat exchange, high-temperature and high-pressure supercritical carbon dioxide is obtained. The high-temperature and high-pressure supercritical carbon dioxide works on the expander 23. The expander 23 is connected to a generator 24. The generated electricity is uniformly entered into the power grid 25 for allocation. After the high-temperature and high-pressure supercritical expansion works, it becomes high-temperature and low-pressure carbon dioxide and enters the hot side inlet of the fourth heat exchanger 6. The low-temperature and low-pressure carbon dioxide at the hot side outlet of the fourth heat exchanger 6 enters the absorption tower 26. The porous liquid absorbent is stored in the absorption tower 26 after being heated and regenerated in the first heat exchanger 3 to absorb the low-temperature and low-pressure carbon dioxide. The porous rich liquid is stored in the low-pressure storage tank 1.

[0060] The present invention adopts a chemical absorption method to achieve storage and release of low-temperature and low-pressure carbon dioxide, and its storage density is much higher than that of carbon dioxide gas phase storage.

[0061] The absorbent is a porous liquid absorbent.

[0062] Porous liquids can provide permanent spaces to hold carbon dioxide, and can achieve high-density distribution of gas molecules in the cavity microenvironment under low pressure. Low-concentration ammonia water can achieve chemical absorption of a large amount of carbon dioxide, and store it in the form of ammonium salts such as ammonium bicarbonate and ammonium carbonate in a carbon-rich solution. Porous liquid absorbents combine the excellent adsorption properties of porous solids and the stable kinetic properties of liquid materials. The absorbent can also be recycled by heating, which can solve the problem of low-pressure storage of carbon dioxide and significantly reduce the system investment cost.

[0063] The porous solid is an ultra-microporous nanomaterial with a hydrophobic inner surface and a hydrophilic outer surface, and can be porous carbon, porous silicon, zeolite, etc. as a cavity to accommodate carbon dioxide.

[0064] Taking ultraporous silica as an example, a certain concentration of tetrapropylammonium hydroxide (TPAOH) aqueous solution was mixed with tetraethyl orthosilicate (TEOS) and stirred for 18 hours, and the hydrolyzed product was subjected to a hydrothermal reaction at 90°C. After the reaction was completed, the above mixture was separated from the solid and liquid to obtain a pure solid product, which was dried and calcined at 550°C to obtain ultraporous silica particles.

[0065] Porous solids can be loaded with basic groups to improve the adsorption selectivity and adsorption capacity of carbon dioxide. Taking ultra-microporous silica as an example, tetraethylenepentamine can be used for directional loading of amine functional groups.

[0066] The porous liquid absorbent is a uniform and stable mixture of porous solid and ammonia water, with a permanent pore structure. Taking ultra-microporous silica as an example, the porous solid can be dispersed in liquid phase by ultrasound or other methods.

[0067] Optionally, the ammonia water may be a low concentration ammonia water of 5% to 25%.

[0068] In the first heat exchanger 3, carbon dioxide desorption and regeneration of the porous liquid absorbent are achieved by heating. In some embodiments, carbon dioxide desorption and regeneration of the absorbent can also be achieved by microwave heating.

[0069] Supercritical carbon dioxide (31.3°C, 7.38MPa) is stored in the high-pressure storage tank 21, which has excellent thermophysical properties and high storage density. Using carbon dioxide as the energy storage medium realizes the utilization and storage of carbon dioxide, which helps to achieve carbon emission reduction.

[0070] The porous liquid-based supercritical carbon dioxide compression energy storage system of the embodiment of the present invention achieves high-density storage of carbon dioxide at the low-pressure end through chemical absorption. The supercritical carbon dioxide compression energy storage system stores excess electricity generated by the renewable energy system and expands to generate electricity during peak electricity consumption, which helps to improve the peak-shaving capacity of the power grid.

[0071] During the low electricity consumption period, the first high temperature medium passes through the outlet of the first high temperature medium storage tank 8, enters the hot side inlet of the first heat exchanger 3 under the action of the second circulation pump 11, heats the porous carbon-rich absorbent and flows out from the hot side outlet of the first heat exchanger 3, and the first low temperature medium enters the first low temperature medium storage tank 7 for storage; the second low temperature medium passes through the outlet of the second low temperature medium storage tank 10, enters the cold side inlet of the second heat exchanger 4 under the action of the fourth circulation pump 13, exchanges heat with the high temperature carbon dioxide and flows out from the cold side outlet of the second heat exchanger 4, and the second high temperature medium enters the second high temperature medium storage tank 9 for storage;

[0072] During peak electricity consumption, the second high-temperature medium passes through the outlet of the second high-temperature medium storage tank 9, enters the hot side inlet of the third heat exchanger 5 under the action of the third circulation pump 14, heats the low-temperature and high-pressure carbon dioxide, and flows out from the hot side outlet of the third heat exchanger 5, and the second low-temperature medium enters the second low-temperature medium storage tank 10 for storage; the first low-temperature medium passes through the outlet of the first low-temperature medium storage tank 7, enters the cold side inlet of the fourth heat exchanger 6 under the action of the first circulation pump 12, exchanges heat with the high-temperature and low-pressure carbon dioxide, and flows out from the cold side outlet of the fourth heat exchanger 6, and the first low-temperature medium enters the first high-temperature medium storage tank 8 for storage.

[0073] It can be understood by those skilled in the art that the medium of the first low-temperature medium storage tank 7 and the first high-temperature medium storage tank 8 is the first medium, and the medium of the second low-temperature medium storage tank 10 and the second high-temperature medium storage tank 9 is the second medium. The first medium and the second medium can be the same medium or different medium.

[0074] It can be understood by those skilled in the art that the low temperatures and high temperatures of the first low temperature medium storage tank 7, the first high temperature medium storage tank 8, the second low temperature medium storage tank 10, and the second high temperature medium storage tank 9 are relative, and the temperature of the first low temperature medium may be higher than that of the second high temperature medium.

[0075] The second heat exchange medium heats the low-temperature and high-pressure supercritical carbon dioxide in the third heat exchanger 5, thereby realizing energy recycling and improving the work quality of the supercritical carbon dioxide.

[0076] Embodiment 2:

[0077] like Figure 2 As shown, the present invention provides a supercritical carbon dioxide energy storage system based on porous liquid absorption storage, comprising

[0078] A low-pressure storage system for storing low-pressure carbon dioxide, the low-pressure storage system having a gas inlet and a storage system outlet;

[0079] A compression energy storage system, connected to the low-pressure storage system, is used to compress the carbon dioxide energy storage medium to obtain high-pressure supercritical carbon dioxide. The compression energy storage system includes an energy storage system inlet and a supercritical carbon dioxide outlet;

[0080] A high-pressure storage system, connected to the outlet of the compressor 16 of the compression energy storage system, for obtaining and storing high-pressure supercritical carbon dioxide, having a storage system inlet and a storage system outlet;

[0081] An expansion energy release system is connected to the high-pressure storage system and is connected to a generator, and is used for high-pressure supercritical expansion energy release and driving the generator to generate electricity, and has an energy release system inlet and an energy release system outlet;

[0082] The heat circulation system is connected to the compression energy storage system and the expansion energy release system, and is distributed in the process of the compression energy storage system and the expansion energy release system. The heat circulation system exchanges heat and circulates heat with the compression energy storage system and the expansion energy release system.

[0083] The low-pressure storage system includes: a low-pressure storage tank 1 and a regeneration tower 28. The low-pressure storage tank 1 is used to store low-pressure carbon dioxide, and the inlet of the low-pressure storage tank 1 is connected to the outlet of the regeneration tower 28 and the outlet of the fourth heat exchanger 6 respectively, and the outlet of the low-pressure storage tank 1 is connected to the inlet of the regeneration tower 28, and a throttle valve 2 is installed on the pipeline connecting the two.

[0084] The compression energy storage system is used to compress the carbon dioxide energy storage medium to obtain high-pressure supercritical carbon dioxide, including a throttle valve 2, a compressor 16, an electric motor 17, a photovoltaic power generation device 18, a wind power generation device 19, and a thermal power generation device 20.

[0085] The inlet of the throttle valve 2 is connected to the outlet of the low-pressure storage tank 1, the outlet of the throttle valve 2 is connected to the inlet of the regeneration tower 28, the outlet of the regeneration tower 28 is respectively connected to the inlet of the low-pressure storage tank 1 and the hot side of the first heat exchanger 3, and the inlet of the compressor 16 is connected to the hot side outlet of the first heat exchanger 3. The inlet of the motor 17 is respectively connected to the photovoltaic power generation device 18, the wind power generation device 19, and the thermal power generation device 20, and the outlet of the motor 17 is connected to the compressor 16.

[0086] The high-pressure storage system is used to store high-pressure supercritical carbon dioxide, mainly a high-pressure storage tank 21. The inlet of the high-pressure storage tank 21 is connected to the outlet of the compressor 16. Low-temperature and high-pressure supercritical carbon dioxide is obtained through the compressor 16. The outlet of the high-pressure storage tank 21 is connected to the inlet of the throttle valve 22.

[0087] The expansion energy release system is used for high-pressure supercritical expansion energy release and driving the generator to generate electricity, including a throttle valve 22, an expander 23, and a generator 24. The inlet of the throttle valve 22 is connected to the outlet of the high-pressure storage tank 21, the outlet of the throttle valve 22 is connected to the cold side inlet of the second heat exchanger 4, the cold side outlet of the third heat exchanger 5 is connected to the inlet of the expander 23, and the outlet of the expander 23 is connected to the hot side inlet of the third heat exchanger 5. The expander 23 is also connected to the generator 24, and the outlet of the generator 24 is connected to the power grid 25 through the power transmission line.

[0088] The heat circulation system is distributed in the compression energy storage and expansion energy release processes, and exchanges and circulates heat with the compression energy storage system and the expansion energy release system, including a first heat exchanger 3, a second heat exchanger 4, a third heat exchanger 5, a first low-temperature medium storage tank 7, a first high-temperature medium storage tank 8, a second circulation pump 11, a first circulation pump 12, and a sixth circulation pump 29.

[0089] The cold side inlet of the first heat exchanger 3 is connected to the outlet of the second circulation pump 11, the cold side outlet of the first heat exchanger 3 is connected to the inlet of the first high-temperature medium storage tank 8, the hot side inlet of the first heat exchanger 3 is connected to the outlet of the regeneration tower 28, and the hot side outlet of the first heat exchanger 3 is connected to the inlet of the compressor 16.

[0090] The hot side inlet of the second heat exchanger 4 is connected to the outlet of the first circulation pump 12, the hot side outlet of the second heat exchanger 4 is connected to the inlet of the first low-temperature medium storage tank 7, the cold side inlet of the second heat exchanger 4 is connected to the outlet of the throttle valve 22, and the cold side outlet of the second heat exchanger 4 is connected to the inlet of the expander 23.

[0091] The outlet of the first low-temperature medium storage tank 7 is connected to the second circulation pump 11 , and the inlet of the first low-temperature medium storage tank 7 is connected to the hot side outlet of the second heat exchanger 4 .

[0092] The inlet of the first high-temperature medium storage tank 8 is connected to the cold side outlet of the first heat exchanger 3 , and the outlet of the first high-temperature medium storage tank 8 is connected to the inlet of the first circulation pump 12 .

[0093] The hot side inlet of the third heat exchanger 5 is connected to the outlet of the expander 23, the hot side outlet of the third heat exchanger 5 is connected to the inlet of the low-pressure storage tank 1, the cold side inlet of the third heat exchanger 5 is connected to the outlet of the sixth circulation pump 29, and the cold side outlet of the third heat exchanger 5 is a high-temperature medium for waste heat utilization.

[0094] The present invention provides an energy storage method of a supercritical carbon dioxide energy storage system based on porous liquid absorption and storage:

[0095] When the electricity consumption is low, the absorbent (porous ionic liquid absorbent) flows out from the outlet of the low-pressure storage tank 1, and is desorbed in the regeneration tower 28 after being adjusted by the throttle valve 2. The high-temperature low-pressure gas separated from the absorbent enters the first heat exchanger 3 from the outlet of the regeneration tower 28 for heat exchange, and the outlet low-temperature low-pressure carbon dioxide gas enters the compressor 16. The excess electricity generated by the photovoltaic power generation device 18, the wind power generation device 19, the thermal power generation device 20 and other devices is transmitted to the motor 17 through the circuit. Under the action of the compressor 16, this part of the excess electricity is converted into the internal energy of low-temperature and high-pressure supercritical carbon dioxide, and the low-temperature and high-pressure supercritical carbon dioxide flows out from the outlet of the compressor 16 and enters the high-pressure storage tank 21 for storage.

[0096] During peak hours of electricity consumption, the low-temperature, high-pressure supercritical carbon dioxide in the high-pressure storage tank 21 is adjusted by the throttle valve 22 and enters the cold side inlet of the second heat exchanger 4. After heat exchange, high-temperature, high-pressure supercritical carbon dioxide is obtained. The high-temperature, high-pressure supercritical carbon dioxide performs work on the expander 23. The expander 23 is connected to a generator 24, and the generated electricity is uniformly sent to the power grid 25 for allocation. After the high-temperature, high-pressure supercritical expansion works, it becomes high-temperature, low-pressure carbon dioxide and enters the hot side inlet of the third heat exchanger 5. The low-temperature, low-pressure carbon dioxide at the hot side outlet of the third heat exchanger 5 enters the low-pressure storage tank 1 and is absorbed and stored by the porous ionic liquid absorbent.

[0097] Optionally, the absorbent used in the present invention is a porous ionic liquid absorbent. The porous liquid absorbent combines the excellent adsorption properties of porous solids and the stable dynamic properties of liquid materials, etc., can provide permanent voids to accommodate carbon dioxide, can achieve high-density distribution of gas molecules in the cavity microenvironment under low pressure, can solve the problem of low-pressure storage end of carbon dioxide, and greatly reduce the system investment cost.

[0098] Optionally, the porous ionic liquid is mainly a suspension composed of a porous guest, a bulky steric hindered solvent, etc., or a pure liquid composed of cavity molecules containing pores themselves, or a pure fluid with a microporous extended framework with intrinsic porosity that melts at high temperature or high pressure and exists in liquid form.

[0099] Optionally, the porous guest provides permanent pores for the porous liquid, mainly advanced porous materials such as metal organic framework materials MOFs, covalent organic porous materials COFs and porous organic polymers POPs.

[0100] Alternatively, the hindered solvent imparts room temperature mobility to the porous guest, which is mainly bulky anions and cations carrying charges.

[0101] Optionally, supercritical carbon dioxide at 31.3°C and 7.38MPa is stored in the high-pressure storage tank 21, which has excellent thermophysical properties and high storage density. Using carbon dioxide as the energy storage medium realizes the utilization and storage of carbon dioxide, which helps to achieve carbon emission reduction.

[0102] The supercritical carbon dioxide compression energy storage system based on porous ionic liquid in the embodiment of the present invention realizes high-density storage of carbon dioxide at the low-pressure end through chemical absorption. The supercritical carbon dioxide compression energy storage system stores excess electricity generated by the renewable energy system and expands to generate electricity during peak electricity consumption, which helps to improve the peak-shaving capacity of the power grid.

[0103] When electricity consumption is low, the outlet of the regeneration tower 28 releases high-temperature carbon dioxide, which enters the hot side inlet of the first heat exchanger 3 for heat exchange, and low-temperature and low-pressure carbon dioxide flows out of the hot side outlet of the first heat exchanger 3. The first low-temperature medium passes through the outlet of the first low-temperature medium storage tank 7, enters the cold side inlet of the first heat exchanger 3 under the action of the second circulation pump 11, and flows out from the cold side outlet of the first heat exchanger 3 after heat exchange with the high-temperature carbon dioxide, and the first high-temperature medium enters the first high-temperature medium storage tank 8 for storage.

[0104] During peak electricity consumption, the first high-temperature medium passes through the outlet of the first high-temperature medium storage tank 8, enters the hot side inlet of the second heat exchanger 4 under the action of the first circulation pump 12, heats the low-temperature and high-pressure carbon dioxide, and flows out from the hot side outlet of the second heat exchanger 4, and the first low-temperature medium enters the first low-temperature medium storage tank 7 for storage. The second low-temperature medium enters the cold side inlet of the third heat exchanger 5 from the outlet of the sixth circulation pump 29, and after heat exchange with the high-temperature carbon dioxide, the second high-temperature medium flows out from the cold side outlet of the third heat exchanger 5, realizing waste heat recovery and improving energy utilization.

[0105] It can be understood by those skilled in the art that the medium in the first low-temperature medium storage tank 7 and the first high-temperature medium storage tank 8 is the first medium, and the medium for waste heat utilization in the sixth circulating pump 29 is the second medium. The first medium and the second medium can be the same medium or different medium.

[0106] Optionally, the first heat exchange medium heats the low-temperature and high-pressure supercritical carbon dioxide in the second heat exchanger 4, thereby realizing energy recycling and improving the work quality of the supercritical carbon dioxide.

[0107] It is to be understood that the present invention is described by some embodiments, and it is known to those skilled in the art that various changes or equivalent substitutions may be made to these features and embodiments without departing from the spirit and scope of the present invention. In addition, under the teachings of the present invention, these features and embodiments may be modified to adapt to specific circumstances and materials without departing from the spirit and scope of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of this application are within the scope of protection of the present invention.

Claims

1. A supercritical carbon dioxide energy storage system based on porous liquid absorption and storage, characterized in that: include A low-pressure storage system for storing low-pressure carbon dioxide; A compression energy storage system, connected to the low-pressure storage system, is used to compress the carbon dioxide energy storage medium; a high-pressure storage system, connected to the compression energy storage system, for obtaining and storing high-pressure supercritical carbon dioxide; An expansion energy release system is connected to the high-pressure storage system and is connected to a generator, and is used for high-pressure supercritical expansion energy release and driving the generator to generate electricity; The heat circulation system is connected to the compression energy storage system and the expansion energy release system, and the heat circulation system performs heat exchange and heat circulation with the compression energy storage system and the expansion energy release system.

2. The supercritical carbon dioxide energy storage system based on porous liquid absorption and storage according to claim 1 is characterized in that: The low-pressure storage system comprises an absorption tower (26), a low-pressure storage tank (1) and a waste heat utilization system; The inlet of the absorption tower (26) is connected to the outlet of the first heat exchanger (3) and the outlet of the fourth heat exchanger (6), respectively; the outlet of the absorption tower (26) is connected to the low-pressure storage tank (1); and the absorption tower (26) is connected to a waste heat utilization system; The low-pressure storage tank (1) is used to store a low-pressure working medium absorbent, and the outlet of the low-pressure storage tank (1) is connected to the inlet of the first heat exchanger (3).

3. The supercritical carbon dioxide energy storage system based on porous liquid absorption and storage according to claim 1 is characterized in that: The heat circulation system comprises a first heat exchanger (3), a second heat exchanger (4), a third heat exchanger (5), a fourth heat exchanger (6), a first low-temperature medium storage tank (7), a first high-temperature medium storage tank (8), a second high-temperature medium storage tank (9), a second low-temperature medium storage tank (10), a second circulation pump (11), a first circulation pump (12), a fourth circulation pump (13) and a third circulation pump (14); The hot side inlet of the first heat exchanger (3) is connected to the outlet of the second circulation pump (11), and the hot side outlet of the first heat exchanger (3) is connected to the inlet of the first low-temperature medium storage tank (7); The cold side inlet of the second heat exchanger (4) is connected to the outlet of the fourth circulation pump (13), and the cold side outlet of the second heat exchanger (4) is connected to the inlet of the second high-temperature medium storage tank (9); The hot side inlet of the third heat exchanger (5) is connected to the outlet of the third circulation pump (14), and the hot side outlet of the third heat exchanger (5) is connected to the inlet of the second low-temperature medium storage tank 10; The cold side inlet of the fourth heat exchanger (6) is connected to the outlet of the first circulation pump (12), and the cold side outlet of the fourth heat exchanger (6) is connected to the inlet of the first high-temperature medium storage tank (8); The outlet of the first low-temperature medium storage tank (7) is connected to the inlet of the first circulation pump (12); The outlet of the first high-temperature medium storage tank (8) is connected to the inlet of the second circulation pump (11); The outlet of the second high-temperature medium storage tank (9) is connected to the inlet of the third circulation pump (14); The outlet of the second cryogenic medium storage tank (10) is connected to the inlet of the fourth circulation pump (13).

4. An energy storage method using the supercritical carbon dioxide energy storage system based on porous liquid absorption and storage according to any one of claims 1 to 3, characterized in that: When electricity consumption is low, the absorbent flows out from the outlet of the low-pressure storage tank (1), is regulated by the throttle valve (2), and is heated in the first heat exchanger (3). The absorbent is heated to release high-temperature low-pressure gas, which flows through the acid washing tower (15) to remove volatile ammonia and water. The carbon dioxide gas at the outlet of the acid washing tower (15) enters the second heat exchanger (4) for heat exchange, and the outlet low-temperature low-pressure carbon dioxide gas enters the compressor (16). The excess electricity generated by the photovoltaic power generation device (18), the wind power generation device (19), and the thermal power generation device (20) is transmitted to the motor (17) through the circuit. Under the action of the compressor (16), this part of the excess electricity is converted into the internal energy of low-temperature high-pressure supercritical carbon dioxide. The low-temperature high-pressure supercritical carbon dioxide flows out from the outlet of the compressor (16) and enters the high-pressure storage tank (21) for storage. During peak hours of electricity consumption, the low-temperature and high-pressure supercritical carbon dioxide in the high-pressure storage tank (21) is regulated by the throttle valve (22) and enters the cold side inlet of the third heat exchanger (5). After heat exchange, high-temperature and high-pressure supercritical carbon dioxide is obtained. The high-temperature and high-pressure supercritical carbon dioxide performs work on the expander (23). After the high-temperature and high-pressure supercritical expansion work, it becomes high-temperature and low-pressure carbon dioxide and enters the hot side inlet of the fourth heat exchanger (6). The low-temperature and low-pressure carbon dioxide at the hot side outlet of the fourth heat exchanger (6) enters the absorption tower (26). The absorbent is stored in the absorption tower (26) after being heated and regenerated in the first heat exchanger (3). The low-temperature and low-pressure carbon dioxide is absorbed and the absorbent is stored in the low-pressure storage tank (1).

5. The energy storage method of the supercritical carbon dioxide energy storage system based on porous liquid absorption and storage according to claim 4, characterized in that: The absorbent is a porous liquid absorbent, which is a mixture of porous solid and ammonia water.

6. The energy storage method of the supercritical carbon dioxide energy storage system based on porous liquid absorption and storage according to claim 5, characterized in that: When electricity consumption is low, the first high-temperature medium passes through the outlet of the first high-temperature medium storage tank (8), enters the hot side inlet of the first heat exchanger (3) under the action of the second circulation pump (11), heats the absorbent and then flows out from the hot side outlet of the first heat exchanger (3), and the first low-temperature medium enters the first low-temperature medium storage tank (7) for storage; The second low-temperature medium passes through the outlet of the second low-temperature medium storage tank (10), enters the cold side inlet of the second heat exchanger (4) under the action of the fourth circulation pump (13), exchanges heat with the high-temperature carbon dioxide, and flows out from the cold side outlet of the second heat exchanger (4), and the second high-temperature medium enters the second high-temperature medium storage tank (9) for storage; During peak hours of electricity consumption, the second high-temperature medium passes through the outlet of the second high-temperature medium storage tank (9), enters the hot side inlet of the third heat exchanger (5) under the action of the third circulation pump (14), heats the low-temperature and high-pressure carbon dioxide, and then flows out from the hot side outlet of the third heat exchanger (5), and the second low-temperature medium enters the second low-temperature medium storage tank (10) for storage; The first low-temperature medium passes through the outlet of the first low-temperature medium storage tank (7) and enters the cold side inlet of the fourth heat exchanger (6) under the action of the first circulation pump (12), and flows out from the cold side outlet of the fourth heat exchanger (6) after heat exchange with the high-temperature low-pressure carbon dioxide. The first low-temperature medium enters the first high-temperature medium storage tank (8) for storage.

7. The supercritical carbon dioxide energy storage system based on porous liquid absorption and storage according to claim 1 is characterized in that: The low-pressure storage system comprises a low-pressure storage tank (1) and a regeneration tower (28); the inlet of the low-pressure storage tank (1) is respectively connected to the outlet of the regeneration tower (28) and the outlet of the fourth heat exchanger (6) of the heat circulation system, the outlet of the low-pressure storage tank (1) is connected to the inlet of the regeneration tower (28), and a throttle valve (2) is installed on the pipeline connecting the two.

8. An energy storage method using the supercritical carbon dioxide energy storage system based on porous liquid absorption and storage according to claim 1, claim 7 or claim 8, characterized in that: When electricity consumption is low, the absorbent flows out from the outlet of the low-pressure storage tank (1), is regulated by the throttle valve (2), and is desorbed in the regeneration tower (28). The high-temperature low-pressure gas separated from the absorbent enters the first heat exchanger (3) of the heat circulation system from the outlet of the regeneration tower (28) for heat exchange. The outlet low-temperature low-pressure carbon dioxide gas enters the compressor (16). The excess electricity generated by the photovoltaic power generation device (18), the wind power generation device (19), and the thermal power generation device (20) is transmitted to the motor (17) through the circuit. Under the action of the compressor (16), this part of the excess electricity is converted into the internal energy of low-temperature high-pressure supercritical carbon dioxide. The low-temperature high-pressure supercritical carbon dioxide flows out from the outlet of the compressor (16) and enters the high-pressure storage tank (21) for storage. During peak hours of electricity consumption, the low-temperature and high-pressure supercritical carbon dioxide in the high-pressure storage tank (21) is regulated by the throttle valve (2) and enters the cold side inlet of the second heat exchanger (4) of the thermal cycle system. After heat exchange, high-temperature and high-pressure supercritical carbon dioxide is obtained. The high-temperature and high-pressure supercritical carbon dioxide performs work on the expander (23). After the high-temperature and high-pressure supercritical expansion work, it becomes high-temperature and low-pressure carbon dioxide and enters the hot side inlet of the third heat exchanger (5) of the thermal cycle system. The low-temperature and low-pressure carbon dioxide at the hot side outlet of the third heat exchanger (5) enters the low-pressure storage tank (1) and is absorbed and stored by the absorbent.

9. The energy storage method of the supercritical carbon dioxide energy storage system based on porous liquid absorption and storage according to claim 8, characterized in that: The absorbent is a porous ionic liquid absorbent, which is a suspension composed of a porous guest, a large-volume steric hindered solvent, or a pure liquid composed of cavity molecules containing pores, or a pure fluid in which a microporous extended framework with intrinsic porosity is melted at high temperature or high pressure and exists in liquid form.

10. The energy storage method of the supercritical carbon dioxide energy storage system based on porous liquid absorption and storage according to claim 9, characterized in that: When electricity consumption is low, the outlet of the regeneration tower (28) releases high-temperature carbon dioxide, which enters the hot side inlet of the first heat exchanger (3) of the heat cycle system for heat exchange, and the hot side outlet of the first heat exchanger (3) flows out low-temperature and low-pressure carbon dioxide. The first low-temperature medium passes through the outlet of the first low-temperature medium storage tank (7), and enters the cold side inlet of the first heat exchanger (3) under the action of the second circulation pump (11) of the heat cycle system. After heat exchange with the high-temperature carbon dioxide, it flows out from the cold side outlet of the first heat exchanger (3), and the first high-temperature medium enters the first high-temperature medium storage tank (8) of the heat cycle system for storage. During peak hours of electricity consumption, the first high-temperature medium passes through the outlet of the first high-temperature medium storage tank (8), enters the hot side inlet of the second heat exchanger (4) under the action of the first circulation pump (12) of the heat circulation system, heats the low-temperature and high-pressure carbon dioxide, and then flows out from the hot side outlet of the second heat exchanger (4). The first low-temperature medium enters the first low-temperature medium storage tank (7) for storage, and the second low-temperature medium enters the cold side inlet of the third heat exchanger (5) from the outlet of the sixth circulation pump (29). After exchanging heat with the high-temperature carbon dioxide, the second high-temperature medium flows out from the cold side outlet of the third heat exchanger (5).

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