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

Abstract

Supercritical carbon dioxide energy storage system and method based on porous liquid absorption storage belong to the technical field of energy storage industry. The system comprises a low-pressure storage system for storing low-pressure carbon dioxide, a compression energy storage system for compressing carbon dioxide energy storage working medium, a high-pressure storage system for obtaining and storing high-pressure supercritical carbon dioxide, an expansion energy release system for high-pressure supercritical expansion energy release and driving a generator to generate electricity, and a heat circulation system for heat exchange and heat circulation with the compression energy storage system and the expansion energy release system. The present application adopts a porous liquid absorbent. Permanent voids for containing carbon dioxide can be provided, the problem of low-pressure carbon dioxide storage end can be solved, and the system investment cost can be greatly reduced. Through the chemical absorption method, high-density storage of low-pressure carbon dioxide is realized, the supercritical carbon dioxide compression energy storage system stores the excess power generated by the renewable energy system, and expands to generate electricity during the power peak, which helps to improve the peak shaving capacity of the power grid.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of energy storage industry, and particularly relates to a supercritical carbon dioxide energy storage system and method based on porous liquid absorption storage. BACKGROUND

[0002] Renewable energy represented by wind energy and solar energy has obvious defects such as volatility, periodicity and uncertainty, so that the power grid with high renewable energy penetration rate faces the challenges of energy balance and power grid stability. On the one hand, the flexibility of thermal power units needs to be improved to enhance the peak shaving capacity of thermal power units, and on the other hand, the introduction of energy storage technology is not only an important means to realize the large-scale access of renewable energy generation, but also can improve the overall efficiency, safety and economy of the power transmission and distribution side.

[0003] The compressed carbon dioxide energy storage technology has many advantages such as high energy storage density, low economic cost, long service life and negative carbon emission, and is suitable for the needs of large-scale long-time energy storage system construction and sustainable development in China, and has very broad development prospects. However, the above energy storage method has great limitations, and the energy density of low-pressure storage is not high enough, which requires a huge storage space. SUMMARY

[0004] The application provides a supercritical carbon dioxide compressed energy storage system based on a porous liquid, which realizes high-density storage of carbon dioxide and can effectively overcome the storage defects of carbon dioxide at low pressure.

[0005] The technical scheme adopted by the application is as follows:

[0006] The supercritical carbon dioxide energy storage system based on porous liquid absorption storage comprises

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

[0008] A compressed energy storage system connected with the low-pressure storage system for compressing carbon dioxide energy storage working medium;

[0009] A high-pressure storage system connected with the compressed energy storage system for obtaining and storing high-pressure supercritical carbon dioxide;

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

[0011] A heat circulation system connected in the compressed energy storage system and the expansion energy release system, and the heat circulation system exchanges and circulates heat with the compressed energy storage system and the expansion energy release system.

[0012] The energy storage method of the supercritical carbon dioxide energy storage system based on porous liquid absorption storage comprises the following steps:

[0013] During the low electricity consumption period, the absorbent flows out from the low-pressure storage tank outlet, is adjusted by the first throttling valve, and is heated in the first heat exchanger, the absorbent releases high-temperature and low-pressure gas by heating, the carbon dioxide gas at the outlet of the pickling tower enters the second heat exchanger for heat exchange, and the low-temperature and low-pressure carbon dioxide gas at the outlet enters the compressor, the surplus power generated by wind power generation, photovoltaic power generation and thermal power generation is transmitted to the motor through the circuit, and the surplus power is converted into the internal energy of the low-temperature and high-pressure supercritical carbon dioxide under the action of the compressor, and the low-temperature and high-pressure supercritical carbon dioxide flows out from the outlet of the compressor and is stored in the high-pressure storage tank;

[0014] During the peak electricity consumption period, the low-temperature and high-pressure supercritical carbon dioxide in the high-pressure storage tank is adjusted by the second throttling valve and enters the cold side inlet of the third heat exchanger, high-temperature and high-pressure supercritical carbon dioxide is obtained after heat exchange, the high-temperature and high-pressure supercritical carbon dioxide does work on the expander, the high-temperature and high-pressure supercritical carbon dioxide becomes high-temperature and low-pressure carbon dioxide after expansion work, 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 regenerated by heating in the first heat exchanger and is stored in the absorption tower, the low-temperature and low-pressure carbon dioxide is absorbed, and the absorbent is stored in the low-pressure storage tank.

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

[0016] During the low electricity consumption period, the absorbent flows out from the low-pressure storage tank outlet, is adjusted by the first throttling valve, and is heated in the first heat exchanger, the absorbent releases high-temperature and low-pressure gas by heating, the carbon dioxide gas at the outlet of the pickling tower enters the second heat exchanger for heat exchange, and the low-temperature and low-pressure carbon dioxide gas at the outlet enters the compressor, the surplus power generated by wind power generation, photovoltaic power generation and thermal power generation is transmitted to the motor through the circuit, and the surplus power is converted into the internal energy of the low-temperature and high-pressure supercritical carbon dioxide under the action of the compressor, and the low-temperature and high-pressure supercritical carbon dioxide flows out from the outlet of the compressor and is stored in the high-pressure storage tank;

[0017] During the peak electricity consumption period, the low-temperature and high-pressure supercritical carbon dioxide in the high-pressure storage tank is adjusted by the second throttling valve and enters the cold side inlet of the third heat exchanger, high-temperature and high-pressure supercritical carbon dioxide is obtained after heat exchange, the high-temperature and high-pressure supercritical carbon dioxide does work on the expander, the high-temperature and high-pressure supercritical carbon dioxide becomes high-temperature and low-pressure carbon dioxide after expansion work, 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 regenerated by heating in the first heat exchanger and is stored in the absorption tower, the low-temperature and low-pressure carbon dioxide is absorbed, and the absorbent is stored in the low-pressure storage tank.

[0018] Compared with the prior art, the present application 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 enhances energy efficiency and utilization.

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

[0021] 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. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a structural diagram of embodiment 1 of the present invention;

[0023] Figure 2 This is a structural diagram of embodiment 2 of the present invention;

[0024] Among them: 1. Low-pressure storage tank; 2. First 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 circulating pump; 12. First circulating pump; 13. Fourth circulating pump; 14. Third circulating pump; 15. Pickling tower; 16. Compressor; 17. Electric motor; 18. Photovoltaic power generation device; 19. Wind power generation device; 20. Thermal power generation device; 21. High-pressure storage tank; 22. Second throttle valve; 23. Expander; 24. Generator; 25. Power grid; 26. Absorption tower; 27. Fifth circulating pump; 28. Regeneration tower; 29. ​​Sixth circulating 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 with reference to the accompanying drawings.

[0026] The critical point of carbon dioxide (7.39 MPa and 31.4°C) is easier to reach than that of air, and supercritical carbon dioxide has properties such as low viscosity, high density, and excellent thermal conductivity. Thermal power plants, where carbon dioxide emissions are most concentrated, have abundant carbon dioxide that, after capture, can serve as an optimal, stable carbon source for compressed carbon dioxide energy storage systems. This enables the storage and utilization of carbon dioxide, contributing to addressing carbon emissions. Establishing a carbon dioxide energy storage system based on thermal power plants is an optimal way to achieve complementary resource advantages.

[0027] The low-pressure end uses porous liquid as a chemical absorption medium to realize high-density storage of gas molecules at low pressure, reduce the volume of the storage device, and solve the low-pressure energy storage problem. According to the change of the power load, the porous liquid releases carbon dioxide, and the power generation capacity of the energy surplus of wind power, photovoltaic and other energy sources can be stored through the compressor absorption at ordinary times, and released and generated during the high power demand of the power grid, which can cooperate with the thermal power plant to improve the load regulation capacity of the power generation system. In the storage process, the chemical reaction energy is used for waste heat utilization, and at the same time, the large amount of waste heat of 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 application reduces the construction cost of the carbon dioxide compression energy storage system, improves the energy conversion efficiency of the energy storage system, and improves the energy efficiency and utilization rate.

[0029] Embodiment one:

[0030] As shown in Figure 1 The present application provides a supercritical carbon dioxide energy storage system based on porous liquid absorption storage, comprising

[0031] A low-pressure storage system is used for storing low-pressure carbon dioxide, and the low-pressure storage system has a gas inlet and a storage system outlet.

[0032] A compression energy storage system is connected with the low-pressure storage system and is used for compressing carbon dioxide energy storage working medium to obtain high-pressure supercritical carbon dioxide, and the compression energy storage system comprises an energy storage system inlet and a supercritical carbon dioxide outlet.

[0033] A high-pressure storage system is connected with the compressor outlet of the compression energy storage system and is used for obtaining and storing high-pressure supercritical carbon dioxide, and has a storage system inlet and a storage system outlet.

[0034] An expansion energy release system is connected with the high-pressure storage system and is connected with 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] A heat circulation system is connected in 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, and the heat circulation system exchanges and circulates heat with the compression energy storage system and the expansion energy release system.

[0036] The low-pressure storage system comprises 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 with the first heat exchanger 3 outlet and the fourth heat exchanger 6 outlet respectively, the absorption tower 26 outlet is connected with the low-pressure storage tank 1, and the absorption tower 26 is further connected with the waste heat utilization system.

[0038] The low-pressure storage tank 1 is used for the storage of low-pressure porous liquid working medium, and the outlet of the low-pressure storage tank 1 is connected with 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 low-pressure storage tank 1 inlet is connected with the outlet of the absorption tower 26, and the first throttling valve 2 is installed on the pipeline connecting the low-pressure storage tank 1 outlet with the inlet of the first heat exchanger 3.

[0040] The inlet and outlet of the waste heat utilization system are connected with the absorption tower 26, and the low-temperature working medium obtains the heat released by the chemical reaction in the absorption tower 26, and 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 circulating pump 27 and a heat exchange working medium, and the fifth circulating pump 27 outlet is a low-temperature working medium, which is used to obtain the chemical energy released by the reaction of 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 and realizes effective energy utilization.

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

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

[0044] The first heat exchanger 3 includes 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 with the outlet of the first throttling 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 with the outlet of the compressor 16 to obtain low-temperature high-pressure supercritical carbon dioxide, and the outlet of the high-pressure storage tank 21 is connected with the inlet of the third heat exchanger 5.

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

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

[0048] 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 circulating pump 11, a first circulating pump 12, a fourth circulating pump 13 and a third circulating pump 14;

[0049] The hot side inlet of the first heat exchanger 3 is connected with the outlet of the second circulating pump 11, the hot side outlet of the first heat exchanger 3 is connected with the inlet of the first low-temperature medium storage tank 7, the cold side inlet of the first heat exchanger 3 is connected with the outlet of the low-pressure storage tank 1, and the cold side outlet of the first heat exchanger 3 is connected with 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 with the outlet of the pickling tower 15, the hot side outlet of the second heat exchanger 4 is connected with the inlet of the compressor 16, the cold side inlet of the second heat exchanger 4 is connected with the outlet of the fourth circulating pump 13, and the cold side outlet of the second heat exchanger 4 is connected with the inlet of the second high-temperature medium storage tank 9;

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

[0052] The hot side inlet of the fourth heat exchanger 6 is connected with the outlet of the expander 23, the hot side outlet of the fourth heat exchanger 6 is connected with the inlet of the absorption tower 26, the cold side inlet of the fourth heat exchanger 6 is connected with the outlet of the first circulating pump 12, and the cold side outlet of the fourth heat exchanger 6 is connected with 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 with the hot side outlet of the first heat exchanger 3, and the outlet of the first low-temperature medium storage tank 7 is connected with the inlet of the first circulating pump 12;

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

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

[0056] The second low-temperature medium storage tank 10 is connected with the hot side outlet of the third heat exchanger 5, and the outlet of the second low-temperature medium storage tank 10 is connected with the inlet of the fourth circulating pump 13.

[0057] The application provides a supercritical carbon dioxide energy storage system based on porous liquid absorption storage,

[0058] During the low electricity consumption period, the porous carbon-rich liquid flows out from the outlet of the low-pressure storage tank 1, is adjusted through the first throttling valve 2, and is heated in the first heat exchanger 3, the porous carbon-rich liquid releases high-temperature low-pressure gas under heating, flows through the pickling tower 15 to remove volatile ammonia and water, the carbon dioxide gas at the outlet of the pickling tower 15 is heat-exchanged in the second heat exchanger 4, the low-temperature low-pressure carbon dioxide gas at the outlet is compressed by 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 an electric circuit, and the excess electricity is converted into the internal energy of the low-temperature high-pressure supercritical carbon dioxide under the action of the compressor 16, and the low-temperature high-pressure supercritical carbon dioxide flows out from the outlet of the compressor 16 and is stored in the high-pressure storage tank 21;

[0059] During the peak electricity consumption period, the low-temperature high-pressure supercritical carbon dioxide in the high-pressure storage tank 21 is adjusted through the second throttling valve 22 and enters the cold side inlet of the third heat exchanger 5, high-temperature high-pressure supercritical carbon dioxide is obtained after heat exchange, the high-temperature high-pressure supercritical carbon dioxide does work on the expander 23, the expander 23 is connected with the generator 24, the generated electricity is uniformly distributed into the power grid 25 for distribution, the high-temperature high-pressure supercritical carbon dioxide becomes high-temperature low-pressure carbon dioxide after expansion work, enters the hot side inlet of the fourth heat exchanger 6, the low-temperature 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 regenerated after being heated in the first heat exchanger 3 and is stored in the absorption tower 26, absorbs the low-temperature low-pressure carbon dioxide, and the porous liquid storage is stored in the low-pressure storage tank 1.

[0060] The application realizes the storage and release of low-temperature low-pressure carbon dioxide by using the chemical absorption method, and the storage density is much higher than that of carbon dioxide gas phase storage.

[0061] The absorbent is a porous liquid absorbent.

[0062] The porous liquid can provide permanent voids for containing carbon dioxide, and can realize high-density distribution of gas molecules in the micro-environment of the cavity at low pressure. Low-concentration ammonia water can realize chemical absorption of a large amount of carbon dioxide, and store the carbon dioxide in the form of ammonium bicarbonate, ammonium carbonate and the like in the carbon-rich solution. The porous liquid absorbent combines the excellent adsorption characteristics of the porous solid and the stable kinetic characteristics of the liquid material, and can realize recycling of the absorbent by heating, thereby solving the problem of low-pressure storage of carbon dioxide and greatly reducing the system investment cost.

[0063] The porous solid is an ultramicroporous nanomaterial with a hydrophobic inner surface and a hydrophilic outer surface, and can be porous carbon, porous silicon, zeolite or the like as a cavity for containing carbon dioxide.

[0064] Taking ultramicroporous silicon dioxide as an example, a certain concentration of tetrapropylammonium hydroxide (TPAOH) aqueous solution is mixed with tetraethyl orthosilicate (TEOS) and stirred for 18 hours, and then hydrolysis is carried out at 90℃. After the reaction is completed, the mixture is separated into solid and liquid to obtain a pure solid product, which is dried and calcined at 550℃ to obtain ultramicroporous silicon dioxide particles.

[0065] The porous solid can be loaded with basic groups to improve the adsorption selectivity and capacity of carbon dioxide. Taking ultramicroporous silicon dioxide as an example, tetraethylenepentamine can be used for directional loading of amine functional groups.

[0066] The porous liquid absorbent is a mixture of uniform and stable porous solid and ammonia water, and has a permanent pore structure. Taking ultramicroporous silicon dioxide as an example, the porous solid can be dispersed in liquid by ultrasonic or the like.

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

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

[0069] The supercritical carbon dioxide (31.3℃, 7.38MPa) stored in the high-pressure storage tank 21 has excellent thermophysical properties and high storage density. Taking carbon dioxide as the energy storage medium, the utilization and sequestration of carbon dioxide are realized, which is helpful for carbon emission reduction.

[0070] The supercritical carbon dioxide compression energy storage system based on the porous liquid of the embodiment of the present application realizes high-density storage of carbon dioxide at low pressure by chemical absorption method. The supercritical carbon dioxide compression energy storage system stores excess power generated by a renewable energy system, and expands to generate power at a power peak, which is helpful for improving the peak shaving capacity of the power grid.

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

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

[0073] 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, the medium in the second low-temperature medium storage tank 10 and the second high-temperature medium storage tank 9 is the second medium, and the first medium and the second medium can be the same medium or different mediums.

[0074] It can be understood by those skilled in the art that the low temperature and high temperature 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 can be higher than that of the second high-temperature medium.

[0075] The second heat exchange medium heats the low-temperature high-pressure supercritical carbon dioxide in the third heat exchanger 5, realizes energy recycling and can improve the working quality of the supercritical carbon dioxide.

[0076] Embodiment two:

[0077] As shown in Figure 2 The present application provides a supercritical carbon dioxide energy storage system based on porous liquid absorption and storage, which comprises

[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 for compressing the carbon dioxide energy storage working medium to obtain high-pressure supercritical carbon dioxide, the compression energy storage system comprising 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, and 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 a generator, and is used for high-pressure supercritical expansion energy release and driving the generator to generate electricity. It 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. Low-pressure storage tank 1 is used to store low-pressure carbon dioxide. Its inlet is connected to the outlet of the regeneration tower 28 and the outlet of the third heat exchanger 5, respectively. The outlet of low-pressure storage tank 1 is connected to the inlet of the regeneration tower 28, and a first 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. It includes a first 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 first throttle valve 2 is connected to the outlet of low-pressure storage tank 1, the outlet of first throttle valve 2 is connected to the inlet of regeneration tower 28, the outlet of regeneration tower 28 is respectively connected to low-pressure storage tank 1 and the hot-side inlet of first heat exchanger 3, and the inlet of compressor 16 is connected to the hot-side outlet of first heat exchanger 3. The inlet of motor 17 is respectively connected to photovoltaic power generation device 18, wind power generation device 19, and thermal power generation device 20, and the outlet of motor 17 is connected to compressor 16.

[0086] The high-pressure storage system is used to store high-pressure supercritical carbon dioxide, mainly consisting of 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, 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 second throttle valve 22.

[0087] The expansion energy release system is used to release energy from high-pressure supercritical expansion and drive a generator for power generation. It includes a second throttle valve 22, an expander 23, and a generator 24. The inlet of the second throttle valve 22 is connected to the outlet of the high-pressure storage tank 21, the outlet of the second 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, the outlet of which is connected to the power grid 25 via a power transmission line.

[0088] The heat circulation system is distributed in the compression energy storage and expansion energy release processes, and exchanges heat with the compression energy storage system and the expansion energy release system, and comprises 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 circulating pump 11, a first circulating pump 12 and a sixth circulating pump 29.

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

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

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

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

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

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

[0095] During the low electricity consumption valley, the absorbent (porous ionic liquid absorbent) flows out from the outlet of the low-pressure storage tank 1, is adjusted through the first throttling valve 2, and is desorbed in the regenerator 28, the high-temperature low-pressure gas separated from the absorbent enters the first heat exchanger 3 from the outlet of the regenerator 28 to exchange heat, and the outlet low-temperature low-pressure carbon dioxide gas enters the compressor 16. The excess electric quantity generated by the photovoltaic power generation device 18, the wind power generation device 19 and the thermal power generation device 20 is delivered to the motor 17 through an electric circuit, and is converted into the internal energy of the low-temperature high-pressure supercritical carbon dioxide under the action of the compressor 16, and the low-temperature high-pressure supercritical carbon dioxide flows out from the outlet of the compressor 16 and is stored in the high-pressure storage tank 21.

[0096] During the power peak, the low-temperature and high-pressure supercritical carbon dioxide in the high-pressure storage tank 21 enters the second heat exchanger 4 cold side inlet after being adjusted by the second throttle valve 22, and high-temperature and high-pressure supercritical carbon dioxide is obtained after heat exchange, the high-temperature and high-pressure supercritical carbon dioxide does work on the expander 23, the expander 23 is connected with the generator 24, and the generated power is uniformly distributed into the power grid 25 for distribution. The high-temperature and high-pressure supercritical carbon dioxide becomes high-temperature and low-pressure carbon dioxide after expansion, enters the third heat exchanger 5 hot side inlet, and the low-temperature and low-pressure carbon dioxide at the third heat exchanger 5 hot side outlet enters the low-pressure storage tank 1 and is absorbed and stored by the porous ionic liquid absorbent.

[0097] Optionally, the present application adopts an absorbent, which is a porous ionic liquid absorbent. The porous liquid absorbent combines the excellent adsorption characteristics of porous solids and the stable kinetic characteristics of liquid materials, and has significant advantages such as providing permanent voids for containing carbon dioxide, enabling high-density distribution of gas molecules in the cavity microenvironment at low pressure, and solving the problem of low-pressure carbon dioxide storage, thereby greatly reducing system investment costs.

[0098] Optionally, the porous ionic liquid is mainly composed of a suspension of porous guests, bulky steric solvents, or a pure liquid of cavity molecules containing pores, or a pure fluid of microporous extended frameworks with intrinsic porosity that melts at high temperature or high pressure and exists in a liquid state.

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

[0100] Optionally, the steric solvent endows the porous guest with room-temperature fluidity, and is mainly composed of bulky anions and cations with charges.

[0101] Optionally, the supercritical carbon dioxide 31.3 DEG C, 7.38 MPa stored in the high-pressure storage tank 21 has excellent thermophysical properties and a high storage density. With carbon dioxide as the energy storage medium, the utilization and sequestration of carbon dioxide are realized, which is helpful for carbon emission reduction.

[0102] The supercritical carbon dioxide compression energy storage system based on the porous ionic liquid of the embodiment of the present application realizes high-density storage of carbon dioxide at a low pressure end through a chemical absorption method, the supercritical carbon dioxide compression energy storage system stores excess power generated by a renewable energy system, and expands to generate power during a power peak, which is helpful for improving the peak shaving capacity of the power grid.

[0103] During the electricity low valley, the high-temperature carbon dioxide released from the outlet of the regenerative tower 28 enters the hot side inlet of the first heat exchanger 3 to exchange heat, and the low-temperature and low-pressure carbon dioxide flows out from the cold side outlet of the first heat exchanger 3. The first low-temperature medium enters the cold side inlet of the first heat exchanger 3 from the outlet of the first low-temperature medium storage tank 7 under the action of the second circulating pump 11, exchanges heat with the high-temperature carbon dioxide, and then flows out from the cold side outlet of the first heat exchanger 3. The first high-temperature medium enters the first high-temperature medium storage tank 8 for storage.

[0104] During the electricity peak, the first high-temperature medium enters the hot side inlet of the second heat exchanger 4 from the outlet of the first high-temperature medium storage tank 8 under the action of the first circulating pump 12, 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. The second low-temperature medium enters the cold side inlet of the third heat exchanger 5 from the outlet of the sixth circulating pump 29, exchanges heat with the high-temperature carbon dioxide, and then the second high-temperature medium flows out from the cold side outlet of the third heat exchanger 5, thereby realizing waste heat recovery and utilization and improving energy utilization rate.

[0105] As can be understood by those skilled in the art, 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 in the sixth circulating pump 29 for waste heat utilization is the second medium. The first medium and the second medium can be the same medium or different mediums.

[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 cycle utilization and improving the work quality of the supercritical carbon dioxide.

[0107] It can be understood that the present application is described by some embodiments, and those skilled in the art can make various changes or equivalent replacements to these features and embodiments without departing from the spirit and scope of the present application. In addition, under the guidance of the present application, these features and embodiments can be modified to adapt to specific conditions and materials without departing from the spirit and scope of the present application. Therefore, the present application is not limited by the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of the present application are within the scope of the present application.

Claims

1. A supercritical carbon dioxide energy storage system based on porous liquid absorption and storage, characterized by: 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; The expansion energy release system is connected to the high-pressure storage system and a generator, and is used for high-pressure supercritical expansion energy release and driving the generator to generate electricity; The heat cycle system is connected to the compression energy storage system and the expansion energy release system. The heat cycle system exchanges heat and circulates heat with the compression energy storage system and the expansion energy release system. 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). The absorption tower (26) is connected to a waste heat utilization system. The low-pressure storage tank (1) is used to store 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). 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 cryogenic 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).

2. An energy storage method using the supercritical carbon dioxide energy storage system based on porous liquid absorption storage according to claim 1, characterized in that: During the off-peak period of electricity consumption, the absorbent flows out from the outlet of the low-pressure storage tank (1), is regulated by the first 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 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), 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, high-pressure supercritical carbon dioxide in the high-pressure storage tank (21) is regulated by the second throttle valve (22) and enters the cold side inlet of the third heat exchanger (5). 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). After the high-temperature, high-pressure supercritical carbon dioxide performs work on expansion, it becomes high-temperature, low-pressure carbon dioxide and enters the hot side inlet of the fourth heat exchanger (6). The low-temperature, low-pressure carbon dioxide at the hot side outlet of the fourth heat exchanger (6) enters the absorption tower (26). The absorbent is heated and regenerated in the first heat exchanger (3) and is stored in the absorption tower (26). The low-temperature, low-pressure carbon dioxide is absorbed and the absorbent is stored in the low-pressure storage tank (1).

3. The energy storage method of the supercritical carbon dioxide energy storage system based on porous liquid absorption storage according to claim 2, characterized in that: The absorbent is a porous liquid absorbent, which is a mixture of porous solid and ammonia water.

4. The energy storage method of the supercritical carbon dioxide energy storage system based on porous liquid absorption storage according to claim 3, characterized in that: During the off-peak period of electricity consumption, the first high-temperature medium passes through the outlet of the first high-temperature medium storage tank (8) and 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 electricity consumption, the second high-temperature medium passes through the outlet of the second high-temperature medium storage tank (9) and 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). 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), exchanges heat with the high-temperature low-pressure carbon dioxide, and then flows out from the cold side outlet of the fourth heat exchanger (6). The first low-temperature medium enters the first high-temperature medium storage tank (8) for storage.

5. A supercritical carbon dioxide energy storage system based on porous liquid absorption and storage, characterized by: 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; The expansion energy release system is connected to the high-pressure storage system and a generator, and is used for high-pressure supercritical expansion energy release and driving the generator to generate electricity; The heat cycle system is connected to the compression energy storage system and the expansion energy release system. The heat cycle system exchanges heat and circulates heat with the compression energy storage system and the expansion energy release system. 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 third heat exchanger (5) 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 first throttle valve (2) is installed on the pipe connecting the two. The heat circulation system includes 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); 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); 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 second throttle valve (22), and the cold side outlet of the second heat exchanger (4) is connected to the inlet of the expander (23); The outlet of the first cryogenic medium storage tank (7) is connected to the second circulation pump (11); The outlet of the first high-temperature medium storage tank (8) is connected to the inlet of the first circulation pump (12); 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.

6. An energy storage method using the supercritical carbon dioxide energy storage system based on porous liquid absorption storage according to claim 5, characterized in that: During the off-peak period of electricity consumption, the absorbent flows out from the outlet of the low-pressure storage tank (1), is regulated by the first 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 cycle 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, high-pressure supercritical carbon dioxide in the high-pressure storage tank (21) is regulated by the second throttle valve (22) and enters the cold side inlet of the second heat exchanger (4) of the thermal cycle system. 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). After the high-temperature, high-pressure supercritical carbon dioxide expands and performs work, it becomes high-temperature, low-pressure carbon dioxide and enters the hot side inlet of the third heat exchanger (5) of the thermal cycle system. 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 absorbent.

7. The energy storage method of the supercritical carbon dioxide energy storage system based on porous liquid absorption storage according to claim 6, characterized in that: The absorbent is a porous ionic liquid absorbent, which is a suspension composed of a porous guest and 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.

8. The energy storage method of the supercritical carbon dioxide energy storage system based on porous liquid absorption storage according to claim 7, characterized in that: During the off-peak period of electricity consumption, 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 electricity consumption, the first high-temperature medium passes through the outlet of the first high-temperature medium storage tank (8) and 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 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).

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