A quicksand energy storage system and operation method for coupling heat storage and gravity energy storage

Abstract

The present invention discloses a quicksand energy storage system and an operation method that couples heat storage and gravity energy storage. The system includes a quicksand lifting system, a solar heating quicksand system, a gravity potential energy power generation system, a hot quicksand storage system, a supercritical carbon dioxide Brayton cycle power generation system, and a cold sand transportation and storage system. The energy storage system uses easily accessible and almost cost-free desert sand as an energy storage medium, and simultaneously utilizes the gravity and heat storage of sand to store energy in the system. In the above manner, the present invention can solve the problem of the difficulty in continuous supply of power generation caused by the intermittent, low-density and instability of new energy sources such as wind energy and solar energy. Considering that the areas in my country that are rich in solar and wind energy resources are also areas close to the desert, the use of sand lifting energy storage power generation technology has good application value and promotion prospects.

Description

Technical Field

[0001] The invention relates to the field of new energy consumption and energy storage, and in particular to a quicksand energy storage system and an operation method for coupling heat storage and gravity energy storage. Background Art

[0002] With the transformation of energy structure and the further improvement of energy conservation and emission reduction technology requirements, the proportion of clean new energy power generation such as wind power generation and solar thermal power generation is constantly increasing. However, due to the strong time-varying and intermittent characteristics of new energy power generation systems such as solar energy and wind energy, they cannot meet the continuous and stable supply of electricity. There are different degrees of wind and solar power abandonment in various places. In addition, due to the access to the grid of wind power and photovoltaic power, coal-fired units have been operating at low load for a long time. Therefore, it is very necessary to store the discontinuous electricity generated by solar and wind energy and convert it into continuous and stable electricity when needed. The development of efficient energy storage technology has become the core and key to solving the problem of new energy consumption and promoting the transformation of the national energy structure.

[0003] At present, many energy storage technologies have been developed at home and abroad, such as pumped storage, concrete potential energy storage, molten salt / hot water heat storage, flywheel, compressor air, battery electrochemical energy storage, supercapacitor, electrolysis hydrogen storage and hybrid energy storage technology composed of several of the above energy storage methods. Among the existing large-scale energy storage technologies, pumped storage power generation technology is the most mature, with large energy storage power, long energy storage time, low energy storage cost and high energy storage efficiency. However, in the northwest region of my country, which is rich in solar and wind energy resources, water resources are scarce, and the construction of pumped storage power stations is greatly restricted. Other energy storage technologies have problems such as high cost, small scale and low technical maturity, making it difficult to develop and apply them on a large scale in the northwest region. Therefore, the development of new energy storage technologies suitable for water-scarce areas in the northwest is of great significance to the consumption and storage of new energy in the region.

[0004] The Northwest region is short of water resources and does not have the conditions for large-scale pumped storage. However, these areas rich in new energy resources such as solar energy and wind energy have vast deserts. Sand itself has the characteristics of easy fluidization, high thermal stability temperature, easy material acquisition, large quantity, low price, and no processing required. It is an ideal medium for energy and heat storage. Therefore, a system that uses quicksand for energy storage can be developed. When wind, light and other new energy sources are abundant, the excess electricity can be lifted to a high position through a sand conveying device for storage. When the power station generates less electricity or stops generating electricity, the sand flows down from a high place to drive the sand turbine to generate electricity. When solar energy is abundant, solar energy can be used to heat the quicksand, and the quicksand can be used to store heat and energy. When the power station generates less electricity or stops generating electricity, the sand can be stored to heat the working fluid and drive the steam turbine to generate electricity, forming a system that uses the potential energy and internal energy of sand to store energy and generate electricity, thereby proposing a new idea for the consumption and storage of new energy in the Northwest region. Compared with other energy storage methods, sand lifting energy storage and quicksand heat storage have the advantages of low energy storage cost, high efficiency, and the ability to achieve large-scale energy storage and power generation. Therefore, they can provide technical support for the consumption and storage of new energy in the Northwest region.

[0005] Therefore, studying and optimizing the coupling of new energy and energy storage systems, using sand as the energy storage medium, and making full use of the gravity and heat storage of sand for energy storage in the same system can solve the problem of difficult continuous power generation caused by the intermittent, low-density and instability of new energy such as wind and solar energy, and the problem that traditional energy storage methods are difficult to achieve in wind and solar energy-rich areas such as the Northwest. Summary of the invention

[0006] The purpose of the present invention is to provide a quicksand energy storage system and an operation method that couples heat storage and gravity energy storage, which can solve the problem of difficult continuous power generation supply caused by the intermittent, low-density and instability of new energy sources such as wind energy and solar energy.

[0007] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0008] A quicksand energy storage system coupling heat storage and gravity energy storage, comprising: a quicksand lifting system 5, a solar heating quicksand system 4, a hot quicksand storage system 1, a supercritical carbon dioxide Brayton cycle power generation system 2, a gravity potential energy power generation system 3 and a cold sand transportation and storage system 6; wherein the quicksand lifting system 5 and the gravity potential energy power generation system 3 are arranged vertically, the solar heating quicksand system 4, the hot quicksand storage system 1 and the cold sand transportation and storage system 6 are arranged horizontally, the solar heating quicksand system 4 and the hot quicksand storage system 1 are arranged at a high position, and the cold sand transportation and storage system 6 is arranged at a low position; the quicksand lifting system 5, the solar heating quicksand system 4, the hot quicksand storage system 1, the gravity potential energy power generation system 3 , the cold sand transport and storage system 6 is connected end to end to form a quicksand circulation channel; the SCO2 of the supercritical carbon dioxide Brayton cycle power generation system 2 and the quicksand heat exchanger 12 are arranged in the quicksand descending channel of the gravity potential energy power generation system 3; the quicksand lifting system 5 includes a sand transport pump 21, a sand lifting impeller 19 and a quicksand lifting channel 23, wherein the sand transport pump 21 is arranged at the entrance of the quicksand lifting channel 23, and the sand lifting impeller 19 is arranged in the quicksand lifting channel 23; the solar heating quicksand system 4 is arranged at the outlet of the quicksand lifting system 5, including a quicksand heating channel, a solar collector 17 arranged at the top of the quicksand heating channel, and a sand turning blade 18 arranged inside the quicksand heating channel; the hot quicksand storage system 1 A first quicksand gate 20 is arranged in the middle; the gravity potential energy power generation system 3 includes a quicksand descending channel, a second quicksand gate 22 arranged at the exit of the quicksand descending channel, a sand turbine 14 arranged directly below the second quicksand gate 22, and a second generator 13 coaxially connected to the sand turbine 14; the cold sand transportation and storage system 6 includes a sand conveying belt 15 and a temporary sand storage area 16; wherein the sand conveying belt 15 is arranged below the sand turbine 14, and the tail end is connected to the temporary sand storage area 16, and the temporary sand storage area 16 is arranged at the entrance of the quicksand lifting system 5; the quicksand energy storage system that couples heat storage and gravity energy storage, when the new energy power generation is sufficient, the system stores energy, and the electric energy generated by the new energy is used to drive the conveying in the quicksand lifting system 5. The sand pump 21 and the sand lifting impeller 19 rotate to lift the sand from the cold sand transport and storage system 6 to the hot quicksand storage system 1, and the quicksand lifting system 5 converts the electrical energy into the gravitational potential energy of the sand for storage; on the other hand, it drives the sand turning blades 18 in the solar heating quicksand system 4 to rotate so that the sand in the solar heating quicksand system 4 is fully heated; when the power generation of new energy is insufficient, the system releases energy outwards. On the one hand, the supercritical carbon dioxide Brayton cycle power generation system 2 utilizes the heat storage of the sand in the hot quicksand storage system 1 to be transferred to the supercritical carbon dioxide Brayton cycle system 2 by the heat exchanger 12, and the supercritical carbon dioxide Brayton cycle converts the thermal energy into electrical energy, and the electrical energy is transmitted to the power grid;On the other hand, the cold sand after releasing heat is transported to the sand turbine 14 through the gravity potential energy power generation system 3, so that the sand turbine 14 rotates to drive the generator 13 to generate electricity, and the generated electricity is transported to the power grid, and the sand after power generation is completed is transported to the temporary sand storage area 16 by the sand conveying belt 15 in the cold sand transport and storage system 6. ;

[0009] The system is constructed as a whole in a deep underground pit, wherein the solar heating quicksand system 4 and the hot quicksand storage system 1 are constructed at the pit mouth for storing gravitational potential energy and heat collection and storage thermal energy at a high position.

[0010] The quicksand lifting system 5 transports the sand from the temporary sand storage area 16 to the bottom of the sand lifting impeller 19 through the sand conveying pump 21 .

[0011] The sand lifting impeller 19 in the quicksand lifting system 5 is a spiral structure impeller, which is driven to rotate by an electric motor to lift sand to the solar heating quicksand system 4.

[0012] The solar collector 17 in the solar heating quicksand system 4 is a concave mirror structure, which concentrates the sunlight to heat the quicksand to store internal energy.

[0013] The sand turning blades 18 in the solar energy heating quicksand system 4 are driven to rotate by a motor, so that the quicksand in the solar energy heating quicksand system 4 is fully heated.

[0014] The supercritical carbon dioxide Brayton cycle power generation system 2 includes a SCO2 and quicksand heat exchanger 12, a SCO2 turbine 9, a SCO2 main compressor 24, a SCO2 recompressor 7, a SCO2 high-temperature regenerator 10, a SCO2 low-temperature regenerator 25, and a cold-end heat exchanger 11 for heat exchange between SCO2 and air; the outlet pipeline of the SCO2 and quicksand heat exchanger 12 is connected to the SCO2 turbine 9, the SCO2 turbine 9 is coaxially connected to the first generator 8, and the outlet channel of the SCO2 turbine 9 is connected to the hot side of the SCO2 high-temperature regenerator 10 and the SCO2 low-temperature regenerator 25. On the hot side of the regenerator 25, the hot side outlet channel of the SCO2 low-temperature regenerator 25 is divided into two parts. The first part passes through the cold end heat exchanger 11 of SCO2 for heat exchange with air and is connected to the SCO2 main compressor 24, and then is connected to the cold side of the SCO2 low-temperature regenerator 25. The second part passes through the SCO2 re-compressor 7 and merges with the first part at the cold side outlet of the SCO2 low-temperature regenerator 25. After the merging, the channel is connected to the cold side inlet of the SCO2 high-temperature regenerator 10, and the cold side outlet of the SCO2 high-temperature regenerator 10 is connected to the inlet of SCO2 and the quicksand heat exchanger 12.

[0015] The system cycle in the supercritical carbon dioxide Brayton cycle power generation system 2 is a supercritical carbon dioxide Brayton cycle simple regenerative cycle or a recompression cycle.

[0016] The cold end heat exchanger 11 for heat exchange between SCO2 and air in the supercritical carbon dioxide Brayton cycle power generation system 2 adopts a forced ventilation air cooler.

[0017] The operation method of the quicksand energy storage system coupling heat storage and gravity energy storage,

[0018] Operation mode 1: When the renewable energy power generation is sufficient, the system stores energy. The electricity generated by the renewable energy is used to drive the sand conveying pump 21 and the sand lifting impeller 19 in the quicksand lifting system 5 to rotate and lift the sand from the cold sand transport and storage system 6 to the hot quicksand storage system 1. The quicksand lifting system converts the electricity into the gravitational potential energy of the sand for storage.

[0019] Operation mode 2: When there is sufficient sunlight, the new energy generates electricity to drive the sand turning blades 18 in the solar heating quicksand system 4 to rotate so that the sand in the solar heating quicksand system 4 is fully heated, and the light energy is converted into quicksand internal energy storage;

[0020] Operation mode 3: When the power generation of new energy is insufficient, the system releases energy outwards, and the supercritical carbon dioxide Brayton cycle power generation system 2 uses the heat storage of sand in the hot quicksand storage system 1 to be transferred from SCO2 and the quicksand heat exchanger 12 to the supercritical carbon dioxide Brayton cycle system 2, and the supercritical carbon dioxide Brayton cycle converts the heat energy into electrical energy, and transmits the electrical energy to the power grid;

[0021] Operation mode 4: When the power generation of new energy is insufficient, the system releases energy outwards. After releasing the heat, the cold sand is transported to the sand turbine 14 through the gravity potential energy power generation system 3, so that the sand turbine 14 rotates to drive the generator 13 to generate electricity, and the generated electricity is transported to the power grid. The sand after power generation is transported to the temporary sand storage area 16 by the sand conveying belt 15 in the cold sand transport and storage system 6.

[0022] The beneficial effects of the present invention are:

[0023] 1. By combining renewable energy power generation with sand gravity and thermal energy storage, all power generated by the renewable energy system can be transmitted to the power grid, avoiding the phenomenon of power abandonment in any renewable energy power generation system;

[0024] 2. By combining renewable energy power generation with sand gravity and thermal energy storage, the frequent start and stop phenomena that occur during the energy storage process of the pure gravity energy storage system are effectively reduced, that is, the input characteristics of the energy storage system are improved, which is beneficial to the improvement of the service life of the components of the gravity energy storage system;

[0025] 3. By combining renewable energy power generation with sand gravity and thermal energy storage, the "power change step characteristics" that occur in the power generation process of the pure gravity energy storage system are avoided, the power output regulation characteristics of the gravity energy storage system power generation process are significantly improved, and the impact on the power grid during the power regulation process is eliminated. At the same time, it is beneficial to increase the service life of system components;

[0026] 4. Establish a storage system that combines sand gravity and thermal energy storage. Compared with the existing more mature pumped storage and battery storage, it can significantly reduce the overall cost of the energy storage system and improve the safety of system operation, making it possible to widely implement this energy storage method in areas rich in solar and wind energy;

[0027] 5. Establish a storage system that combines sand gravity and thermal energy storage. After large-scale application, the system can be used to achieve grid frequency response and significantly improve the operation quality of the grid; BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a schematic diagram of a system of the present invention for generating electricity from renewable energy combined with sand gravity and thermal energy storage;

[0029] The components in the attached drawings are marked as follows: 1. hot quicksand storage system; 2. supercritical carbon dioxide Brayton cycle power generation system; 3. gravity potential energy power generation system; 4. solar heating quicksand system; 5. quicksand lifting system; 6. cold sand transportation and storage system; 7. SCO2 recompressor; 8. first generator; 9. SCO2 turbine; 10. SCO2 high-temperature regenerator; 11. cold-end heat exchanger for SCO2 and air; 12 SCO2 and quicksand heat exchanger; 13. second generator; 14. sand turbine; 15. sand conveying belt; 16. temporary sand storage area; 17. solar collector; 18. sand turning blades; 19. sand lifting impeller; 20. first quicksand gate; 21. sand conveying pump; 22. second quicksand gate; 23. quicksand lifting channel; 24. SCO2 main compressor; 25. SCO2 low-temperature regenerator. DETAILED DESCRIPTION

[0030] The present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0031] See also Figure 1 The present invention is a quicksand energy storage system that couples heat storage and gravity energy storage, including: quicksand lifting system 5, solar heating quicksand system 4, hot quicksand storage system 1, supercritical carbon dioxide Brayton cycle power generation system 2, gravity potential energy power generation system 3, cold sand transportation and storage system 6. The system is built in a deep underground pit, in which the energy storage module composed of the solar heating quicksand system 4 and the hot quicksand storage system 1 is built at the pit mouth, which is used to store gravity potential energy and heat collection and storage heat energy at a high position.

[0032] The quicksand lifting system 5 includes a quicksand lifting channel 23, a sand conveying pump 21 and a sand lifting impeller 19 placed in the quicksand lifting channel 23. The system conveys sand from the temporary sand storage area 16 to the bottom of the sand lifting impeller 19 through the sand conveying pump 21, and then the sand lifting impeller 19 with a spiral structure lifts the sand to the solar heating quicksand system 4.

[0033] The solar heating quicksand system 4 includes a solar collector 17 and a sand turning blade 18. The solar collector 17 is a concave mirror structure, which can concentrate sunlight to heat the quicksand to store internal energy. The sand turning blade 18 is driven by a motor to rotate, so that the quicksand in the solar heating quicksand system 4 is fully heated.

[0034] A supercritical carbon dioxide Brayton cycle power generation system 2 comprises a SCO2 and quicksand heat exchanger 12, a SCO2 turbine 9, a SCO2 main compressor 24, a SCO2 recompressor 7, a SCO2 high-temperature regenerator 10, a SCO2 low-temperature regenerator 25, and a cold-end heat exchanger 11 for heat exchange between SCO2 and air; the outlet pipeline of the SCO2 and quicksand heat exchanger 12 is connected to the SCO2 turbine 9, the SCO2 turbine 9 is coaxially connected to the first generator 8, the outlet channel of the SCO2 turbine 9 is connected to the hot side of the SCO2 high-temperature regenerator 10 and the hot side of the SCO2 low-temperature regenerator 25, and the hot side outlet channel of the SCO2 low-temperature regenerator 25 is split into two parts. The first part passes through the cold end heat exchanger 11 of SCO2 for heat exchange with air and is connected to the SCO2 main compressor 24, and then to the cold side of the SCO2 low temperature regenerator 25. The second part passes through the SCO2 recompressor 7 and merges with the first part at the cold side outlet of the SCO2 low temperature regenerator 25. After merging, the channel is connected to the cold side inlet of the SCO2 high temperature regenerator 10. The cold side outlet of the SCO2 high temperature regenerator 10 is connected to the inlet of the SCO2 and quicksand heat exchanger 12. The system cycle is a simple regenerative cycle or a recompression cycle of the supercritical carbon dioxide Brayton cycle. The SCO2 and quicksand heat exchanger 12 are arranged in the descending pipe section before the inlet of the gravity potential energy power generation system. The cold end heat exchanger adopts a forced ventilation air cooler.

[0035] The gravity potential energy power generation system 3 includes a quicksand descending channel, a quicksand gate 22, a grinding wheel machine 14 and a generator 13. When the system releases gravity potential energy to generate electricity, the quicksand drives the grinding wheel machine 14 to rotate, thereby driving the generator 13 to rotate to generate electricity.

[0036] The cold sand transport and storage system 6 comprises a sand transport belt 15 and a temporary sand storage area 16. The sand transport belt transmits the cold sand after the gravitational potential energy generation to the temporary sand storage area 16 for storage.

[0037] The operation method of the quicksand energy storage system coupling heat storage and gravity energy storage is as follows:

[0038] Operation mode 1: When the renewable energy power generation is sufficient, the system stores energy. The electricity generated by the renewable energy is used to drive the sand conveying pump 21 and the sand lifting impeller 19 in the quicksand lifting system 5 to rotate and lift the sand from the cold sand transport and storage system 6 to the hot quicksand storage system 1. The quicksand lifting system converts the electricity into the gravitational potential energy of the sand for storage.

[0039] Operation mode 2: When there is sufficient sunlight, the new energy generates electricity to drive the sand turning blades 18 in the solar heating quicksand system 4 to rotate so that the sand in the solar heating quicksand system 4 is fully heated, and the light energy is converted into quicksand internal energy storage;

[0040] Operation mode 3: When the power generation of new energy is insufficient, the system releases energy outwards, and the supercritical carbon dioxide Brayton cycle power generation system 2 uses the heat storage of sand in the hot quicksand storage system 1 to be transferred from SCO2 and the quicksand heat exchanger 12 to the supercritical carbon dioxide Brayton cycle system 2, and the supercritical carbon dioxide Brayton cycle converts the heat energy into electrical energy, and transmits the electrical energy to the power grid;

[0041] Operation mode 4: When the power generation of new energy is insufficient, the system releases energy outwards. After releasing the heat, the cold sand is transported to the sand turbine 14 through the gravity potential energy power generation system 3, so that the sand turbine 14 rotates to drive the generator 13 to generate electricity, and the generated electricity is transported to the power grid. The sand after power generation is transported to the temporary sand storage area 16 by the sand conveying belt 15 in the cold sand transport and storage system 6.

[0042] The above description is only an implementation mode of the present invention, and does not limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made by using the contents of the present invention specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A quicksand energy storage system that couples heat storage and gravity energy storage, characterized in that: include: A quicksand lifting system (5), a solar heating quicksand system (4), a hot quicksand storage system (1), a supercritical carbon dioxide Brayton cycle power generation system (2), a gravity potential energy power generation system (3) and a cold sand transportation and storage system (6); wherein the quicksand lifting system (5) and the gravity potential energy power generation system (3) are arranged vertically, the solar heating quicksand system (4), the hot quicksand storage system (1) and the cold sand transportation and storage system (6) are arranged horizontally, and the solar heating quicksand system (4) and the hot quicksand storage system (1) are arranged at The cold sand transport and storage system (6) is arranged at a high position, and the cold sand transport and storage system (6) is arranged at a low position; the quicksand lifting system (5), the solar heating quicksand system (4), the hot quicksand storage system (1), the gravity potential energy power generation system (3), and the cold sand transport and storage system (6) are connected end to end to form a quicksand circulation channel; the SCO2 of the supercritical carbon dioxide Brayton cycle power generation system (2) and the quicksand heat exchanger (12) are arranged in the quicksand descending channel of the gravity potential energy power generation system (3); the quicksand lifting system (5) includes a sand transport pump (21), a sand lifting impeller (19 ) and a quicksand lifting channel (23), wherein a sand delivery pump (21) is arranged at the entrance of the quicksand lifting channel (23), and a sand lifting impeller (19) is arranged in the quicksand lifting channel (23); a solar energy heating quicksand system (4) is arranged at the exit of the quicksand lifting system (5), comprising a quicksand heating channel, a solar energy collector (17) arranged at the top of the quicksand heating channel, and a sand turning blade (18) arranged inside the quicksand heating channel; a first quicksand gate (20) is arranged in the hot quicksand storage system (1); a gravitational potential energy power generation system ( 3) comprising a quicksand descending channel, a second quicksand gate (22) arranged at the exit of the quicksand descending channel, a sand turbine (14) arranged directly below the second quicksand gate (22), and a second generator (13) coaxially connected to the sand turbine (14); the cold sand transport and storage system (6) comprises a sand transport belt (15) and a temporary sand storage area (16); wherein the sand transport belt (15) is arranged below the sand turbine (14) and its tail end is connected to the temporary sand storage area (16), and the temporary sand storage area (16) is arranged at the entrance of the quicksand lifting system (5); The quicksand energy storage system coupled with heat storage and gravity energy storage stores energy when the power generation from renewable energy is sufficient. The electric energy generated by renewable energy is used to drive the sand transport pump (21) and the sand lifting impeller (19) in the quicksand lifting system (5) to rotate and lift the sand from the cold sand transport and storage system (6) to the hot quicksand storage system (1). The electric energy is converted into the gravitational potential energy of the sand through the quicksand lifting system (5) for storage. On the other hand, the quicksand lifting system (5) drives the sand turning blades (18) in the solar heating quicksand system (4) to rotate so that the sand in the solar heating quicksand system (4) is fully heated. When the power generation from renewable energy is insufficient, the system releases energy to the outside. On the one hand, the electric energy generated by the renewable energy is used to drive the sand transport pump (21) and the sand lifting impeller (19) in the quicksand lifting system (5) to rotate and lift the sand from the cold sand transport and storage system (6) to the hot quicksand storage system (1). The supercritical carbon dioxide Brayton cycle power generation system (2) utilizes the heat stored in the sand in the hot sand storage system (1) to be transferred to the supercritical carbon dioxide Brayton cycle system (2) through a heat exchanger (12), and the supercritical carbon dioxide Brayton cycle converts the heat energy into electrical energy, and transmits the electrical energy to the power grid; on the other hand, the cold sand that has released the heat is transported to the sand turbine (14) through the gravity potential energy power generation system (3), so that the sand turbine (14) rotates to drive the generator (13) to generate electricity, and the generated electricity is transmitted to the power grid, and the sand that has completed the power generation is transported to the temporary sand storage area (16) through the sand conveying belt (15) in the cold sand transportation and storage system (6).

2. The quicksand energy storage system coupling heat storage and gravity energy storage according to claim 1 is characterized in that: The system is constructed as a whole in a deep underground pit, wherein a solar heating quicksand system (4) and a hot quicksand storage system (1) are constructed at the pit mouth for storing gravitational potential energy and heat collection and storage thermal energy at a high position.

3. The quicksand energy storage system coupling heat storage and gravity energy storage according to claim 1 is characterized in that: The quicksand lifting system (5) transports sand from the temporary sand storage area (16) to the bottom of the sand lifting impeller (19) through a sand conveying pump (21).

4. The quicksand energy storage system coupling heat storage and gravity energy storage according to claim 1 is characterized in that: The sand lifting impeller (19) in the quicksand lifting system (5) is a spiral structure impeller, which is driven to rotate by an electric motor to lift sand to the solar energy heating quicksand system (4).

5. The quicksand energy storage system coupling heat storage and gravity energy storage according to claim 1 is characterized in that: The solar collector (17) in the solar heating quicksand system (4) is a concave mirror structure, which collects sunlight to heat the quicksand in a concentrated manner to store internal energy.

6. The quicksand energy storage system coupling heat storage and gravity energy storage according to claim 1, characterized in that: The sand turning blades (18) in the solar energy heating quicksand system (4) are driven to rotate by a motor, so that the quicksand in the solar energy heating quicksand system (4) is fully heated.

7. The quicksand energy storage system coupling heat storage and gravity energy storage according to claim 1 is characterized in that: The supercritical carbon dioxide Brayton cycle power generation system (2) comprises a SCO2 and quicksand heat exchanger (12), a SCO2 turbine (9), a SCO2 main compressor (24), a SCO2 recompressor (7), a SCO2 high temperature regenerator (10), a SCO2 low temperature regenerator (25) and a cold end heat exchanger (11) for SCO2 and air heat exchange; the outlet pipeline of the SCO2 and quicksand heat exchanger (12) is connected to the SCO2 turbine (9), the SCO2 turbine (9) is coaxially connected to the first generator (8), and the outlet channel of the SCO2 turbine (9) is connected to the hot side of the SCO2 high temperature regenerator (10) and the SCO2 turbine (9). The hot side of the O2 low-temperature regenerator (25), the hot side outlet channel of the SCO2 low-temperature regenerator (25) is divided into two parts, the first part passes through the cold end heat exchanger (11) of SCO2 for heat exchange with air and is connected to the SCO2 main compressor (24), and then connected to the cold side of the SCO2 low-temperature regenerator (25); the second part passes through the SCO2 recompressor (7) and merges with the first part at the cold side outlet of the SCO2 low-temperature regenerator (25), and the channel after merging is connected to the cold side inlet of the SCO2 high-temperature regenerator (10), and the cold side outlet of the SCO2 high-temperature regenerator (10) is connected to the inlet of SCO2 and the quicksand heat exchanger (12).

8. The quicksand energy storage system coupling heat storage and gravity energy storage according to claim 7, characterized in that: The system cycle in the supercritical carbon dioxide Brayton cycle power generation system (2) is a supercritical carbon dioxide Brayton cycle simple regenerative cycle or a recompression cycle.

9. The quicksand energy storage system coupling heat storage and gravity energy storage according to claim 7, characterized in that: The cold end heat exchanger (11) for heat exchange between SCO2 and air in the supercritical carbon dioxide Brayton cycle power generation system (2) adopts a forced ventilation air cooler.

10. The method for operating the quicksand energy storage system coupling heat storage and gravity energy storage according to any one of claims 1 to 9, characterized in that: Operation mode 1: When the renewable energy power generation is sufficient, the system stores energy. The electric energy generated by the renewable energy is used to drive the sand conveying pump (21) and the sand lifting impeller (19) in the quicksand lifting system (5) to rotate and lift the sand from the cold sand transport and storage system (6) to the hot quicksand storage system (1). The electric energy is converted into the gravitational potential energy of the sand through the quicksand lifting system for storage. Operation mode 2: When there is sufficient sunlight, the new energy generates electricity to drive the sand turning blades (18) in the solar heating quicksand system (4) to rotate so that the sand in the solar heating quicksand system (4) is fully heated, and the light energy is converted into quicksand internal energy for storage; Operation mode 3: When the power generation of new energy is insufficient, the system releases energy externally, and the supercritical carbon dioxide Brayton cycle power generation system (2) uses the heat stored in the sand in the hot quicksand storage system (1) to transfer the heat to the supercritical carbon dioxide Brayton cycle system (2) through SCO2 and the quicksand heat exchanger (12), and the supercritical carbon dioxide Brayton cycle converts the heat energy into electrical energy, and transmits the electrical energy to the power grid; Operation mode 4: When the power generation of new energy is insufficient, the system releases energy outwards. After releasing the heat, the cold sand is transported to the sand turbine (14) through the gravity potential energy power generation system (3), so that the sand turbine (14) rotates and drives the generator (13) to generate electricity, and the generated electricity is transported to the power grid. At the same time, the sand after power generation is transported to the temporary sand storage area (16) through the sand conveying belt (15) in the cold sand transport and storage system (6).

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