Heat pump type molten salt-carbon composite energy storage power supply method and device

Abstract

This invention provides a heat pump-type molten salt-carbon composite energy storage method, comprising: a heat storage and cold storage mode: the gaseous working medium is adiabatically compressed by a compressor, undergoes isobaric heat release through a heat storage system to store heat in molten salt, enters a turbine for adiabatic expansion to perform work, and undergoes isobaric heat absorption through a cold storage system to store heat in compressed carbon dioxide, and this process is repeated; a power generation mode: the working medium circulates in a high-temperature heat engine system, during which it absorbs heat isobarically through a heat storage system and releases heat isobarically through a cold storage system to perform work for power generation; the heat exchange between the working medium and the cold storage system causes the cold storage system to absorb heat, and the gaseous carbon dioxide obtained after heat absorption performs work and is used for power generation. This invention solves the problems of renewable energy curtailment and peak-valley electricity by using a reversible heat pump energy storage and heat engine power generation method and device, and utilizes carbon dioxide obtained from carbon capture technology as a new energy storage medium while storing energy for power generation.

Description

Technical Field

[0001] This invention relates to an energy storage power supply method and apparatus, and more particularly to a heat pump type molten salt-carbon composite energy storage power supply method and apparatus. Background Technology

[0002] Global warming is a major challenge facing humanity. Our country has set a general goal of peaking carbon emissions before 2030 and achieving carbon neutrality before 2060. Carbon dioxide is a primary cause of global warming, and carbon capture technology offers a technological solution to this problem. How to effectively utilize captured carbon dioxide is a topic worthy of further research.

[0003] In existing technologies, carbon dioxide is generally treated through underground sequestration, where captured carbon dioxide is injected into deep geological reservoirs, isolating it from the atmosphere for a long period and putting it into a "dormant state." The main sequestration methods include terrestrial sequestration, marine sequestration, and carbonation solids sequestration. A drawback of these methods is the waste of carbon dioxide resources.

[0004] On the other hand, vigorously developing clean energy sources, such as solar and wind power, is an important way to achieve carbon neutrality. Clean energy is generally affected by natural conditions such as weather, seasons, and sunlight, making it difficult to provide stable energy output and thus difficult to match the power grid. Therefore, the problem of wind and solar power curtailment is very serious at present. To enable green energy to output electricity more evenly distributed over time, adopting certain energy storage technologies—trading space for time—is a good solution.

[0005] Currently, energy storage technologies include electric heating energy storage and heat pump energy storage. Electric heating energy storage achieves thermal energy storage by electrically heating molten salt, and its thermal storage efficiency cannot exceed 100%. Heat pump energy storage utilizes thermodynamic cycles to convert low-temperature heat into high-temperature heat, so that the stored heat exceeds the consumed electrical energy, but its thermal storage efficiency needs to be further improved. Summary of the Invention

[0006] The purpose of this invention is to provide a highly efficient heat pump-type molten salt-carbon composite energy storage method and device to solve the shortcomings of low thermal energy storage efficiency, and at the same time solve the problem of processing carbon dioxide obtained from carbon capture.

[0007] To achieve the above objectives, this application draws upon the principle of the reversibility of the Carnot cycle and the reverse Carnot cycle in thermodynamics. It utilizes the reverse Carnot cycle to transfer heat from a low-temperature heat source to a high-temperature heat source, achieving molten salt thermal storage and carbon dioxide cold storage energy. Then, the heat from the high-temperature heat source is transferred back to the low-temperature heat source, releasing energy to generate electricity. However, in reality, the physical processes of the Carnot cycle and the reverse Carnot cycle are difficult to realize. Therefore, this invention utilizes the reverse Brayton cycle to achieve molten salt thermal storage and carbon dioxide cold storage energy. Simultaneously, the high-temperature and low-temperature heat engine cycles are combined to generate electricity. Theoretically, the conversion efficiency of energy storage followed by power generation is generally superior to traditional methods such as direct electric heating. Furthermore, this energy storage method uses carbon dioxide as a cold storage medium, effectively utilizing carbon dioxide captured from carbon, turning waste into treasure, and contributing to the achievement of carbon neutrality.

[0008] Therefore, the present invention provides a heat pump type molten salt-carbon composite energy storage method, which includes the following modes:

[0009] (1) Heat and cold storage mode based on reverse Brayton cycle: the gas working medium is adiabatically compressed by the compressor and then heat exchanged with the heat storage system to achieve isobaric heat release of the gas working medium. The heat storage medium of the heat storage system is molten salt, so that heat is stored in the molten salt. Then it enters the turbine for adiabatic expansion to do work. Then it achieves isobaric heat absorption of the gas working medium and isobaric heat release of compressed carbon dioxide by heat exchange with the carbon dioxide condenser. After isobaric heat release, the compressed carbon dioxide is condensed into liquid carbon dioxide and stored in the liquid carbon dioxide storage tank. Then the gas working medium is adiabatically compressed again by the compressor to repeat the above process.

[0010] (2) Power generation mode based on Brayton cycle or Rankine cycle: The working medium circulates in the high-temperature heat engine system. During the circulation process, it exchanges heat with the heat storage system to achieve isobaric heat absorption of the gaseous working medium. It exchanges heat with the carbon dioxide evaporator to achieve isobaric heat release of the gaseous working medium and isobaric heat absorption of liquid carbon dioxide. The work done by the working medium during the circulation process is used for power generation. After the liquid carbon dioxide absorbs heat through the carbon dioxide evaporator, it vaporizes. During the vaporization process, the volume of carbon dioxide expands by more than 500 times and obtains 20-60 MPa high-pressure gaseous carbon dioxide to do work and generate electricity.

[0011] The high-temperature heat engine system is a high-temperature Brayton heat engine system. In the high-temperature Brayton heat engine system, the gaseous working medium enters the compressor for adiabatic compression, and then exchanges heat with the heat storage system to achieve isobaric heat absorption of the gaseous working medium. Then it enters the turbine for adiabatic expansion to do work, and exchanges heat with the carbon dioxide evaporator to achieve isobaric heat release of the gaseous working medium. Subsequently, the gaseous working medium enters the compressor again to repeat the above steps or is discharged to the outside.

[0012] The high-temperature heat engine system is a high-temperature Rankine heat engine system. In this system, the liquid Rankine cycle working medium undergoes isobaric heat absorption through heat exchange with the heat storage system via a working medium evaporator, becoming a steam-form Rankine cycle working medium. The steam-form Rankine cycle working medium adiabatically expands and performs work in the turbine, and the exhaust gas releases heat at isobaric pressure in the carbon dioxide evaporator, condensing into a condensed liquid Rankine cycle working medium. Simultaneously, the liquid carbon dioxide absorbs heat from the Rankine cycle working medium and evaporates into gaseous carbon dioxide. Finally, the liquid Rankine cycle working medium is adiabatically compressed by a working fluid pump and re-enters the evaporator to repeat the above steps.

[0013] The heat exchange between the gaseous working medium and the carbon dioxide evaporator enables the low-temperature heat engine system to absorb heat from the high-temperature heat engine system or the air using the carbon dioxide evaporator. The low-temperature heat engine system is a low-temperature Rankine heat engine system. In the low-temperature Rankine heat engine system, liquid carbon dioxide in the cold storage system enters the carbon dioxide evaporator to absorb heat from the gaseous working medium of the high-temperature heat engine system, or directly absorbs heat from the air, causing the liquid carbon dioxide to absorb heat and vaporize. During the vaporization process, the volume of carbon dioxide expands more than 500 times, resulting in high-pressure gaseous carbon dioxide at 20-60 MPa. The high-pressure gaseous carbon dioxide enters the low-temperature heat engine turbine for adiabatic expansion to perform work for power generation, and then the waste gas is collected.

[0014] The working gas medium includes air, argon, nitrogen, helium, or carbon dioxide.

[0015] The working medium of the Rankine cycle includes water, ammonia solution, and at least one of hydrocarbons, alcohols, ethers, esters, ketones, aldehydes, phenols, carboxylic acids, amines, glycol derivatives, and heterocyclic compounds.

[0016] On the other hand, the present invention provides a heat pump type molten salt-carbon composite energy storage and power supply device, characterized in that it is based on the heat pump type energy storage and power supply method described above.

[0017] Corresponding to the heat storage and cold storage mode, it includes a compressor that is connected in series along the direction of the gas working medium to form a loop, a molten salt gas heat exchanger connected to the heat storage system, a turbine, and a carbon dioxide condenser connected to the cold storage system.

[0018] Corresponding to the power generation mode, it includes high-temperature heat engine systems and low-temperature heat engine systems;

[0019] The high-temperature heat engine system includes a compression device connected in series along the direction of the working gas medium via pipelines, a molten salt gas heat exchange device connected to the heat storage system, a power generation device, and a carbon dioxide evaporator connected to the cold storage system.

[0020] When the high-temperature heat engine system is a high-temperature Brayton heat engine system, the compression device is a compressor, the power generation device is a turbine, and the molten salt gas heat exchange device is a molten salt gas heat exchanger.

[0021] When the high-temperature heat engine system is a high-temperature Rankine heat engine system, the compression device is a working fluid pump, the molten salt gas heat exchange device is a working medium evaporator, the power generation device is a steam turbine, and the high-temperature heat engine system forms a loop.

[0022] The low-temperature heat engine system includes the cold storage system, the carbon dioxide evaporator, the low-temperature heat engine turbine, and the carbon dioxide recovery system connected in series. The cold storage system exchanges heat with the gas working medium of the high-temperature heat engine system through the carbon dioxide evaporator, or it exchanges heat directly with the air through the carbon dioxide evaporator.

[0023] The heat storage medium of the heat storage system is molten salt, and the cold storage medium of the cold storage system is carbon dioxide.

[0024] The carbon dioxide condenser is used for heat exchange between the gas working medium and compressed carbon dioxide in the heat storage and cold storage mode, so as to achieve isobaric heat absorption of the gas working medium in the heat storage and cold storage mode, and at the same time realize the condensation of compressed carbon dioxide.

[0025] The heat storage system includes at least two interconnected heat storage medium insulation containers with different internal heat storage medium temperatures, or at least one interconnected heat storage medium insulation container with an inclined temperature layer having a temperature gradient in its internal heat storage medium.

[0026] The heat storage medium includes one of nitrates, chlorides, and fluorides.

[0027] The carbon dioxide cold storage system includes a carbon dioxide compressor, a carbon dioxide condenser, and a liquid carbon dioxide storage tank connected in sequence.

[0028] The heat pump-type molten salt-carbon composite energy storage and power supply method of this invention effectively combines carbon dioxide storage with heat pump energy storage technology. Specifically, it achieves molten salt thermal energy storage and carbon dioxide cold energy storage through heat pump energy storage; simultaneously, during power generation, a high-temperature heat engine (Bretton cycle or Rankine cycle) realizes the heat-work conversion of molten salt thermal energy, and a low-temperature heat engine converts the cold energy storage of carbon dioxide into electrical energy. Thus, on the one hand, it achieves high-efficiency heat pump energy storage superior to traditional electric heating energy storage, and on the other hand, it solves the problem of carbon dioxide treatment obtained from carbon capture by using carbon dioxide as a cold storage medium. Attached Figure Description

[0029] Figure 1 This is a schematic diagram illustrating the principle of the heat pump-type molten salt-carbon composite energy storage and power supply method according to the first embodiment of the present invention in the heat storage and cold storage mode.

[0030] Figure 2 This is a schematic diagram of the heat pump-type molten salt-carbon composite energy storage power supply method according to the first embodiment of the present invention in the power generation mode.

[0031] Figure 3 This is a schematic diagram of the heat pump-type molten salt-carbon composite energy storage power supply method according to the second embodiment of the present invention in the power generation mode.

[0032] Figure label:

[0033] 1. Compressor

[0034] 2. Turbine

[0035] 3. Carbon dioxide condenser

[0036] 4. Molten salt gas heat exchanger

[0037] 5. Low-temperature molten salt tank

[0038] 6. High-temperature molten salt tank

[0039] 7. Compressed carbon dioxide storage tank

[0040] 8. Cryogenic liquid carbon dioxide storage tank

[0041] 10. Carbon dioxide evaporator

[0042] 11. Low-temperature thermal turbine

[0043] 12. Carbon dioxide compressor

[0044] 13. Evaporator for working medium

[0045] 14. Superheater

[0046] 15. Steam turbine

[0047] 16. Regenerative heat exchanger

[0048] 18. Working fluid pump Detailed Implementation

[0049] The present invention will be further described below with reference to specific embodiments. It should be understood that the following embodiments are for illustrative purposes only and are not intended to limit the scope of the invention.

[0050] First embodiment: Heat pump type molten salt-carbon composite energy storage power supply method

[0051] Figure 1A schematic diagram of the heat pump-type molten salt-carbon composite energy storage and power supply method according to the first embodiment of the present invention is provided in a heat storage and cold storage mode based on the reverse Brayton cycle. The room temperature gaseous working medium enters compressor 1 and undergoes adiabatic compression. For a given compression ratio P, the gaseous working medium is compressed into a high-temperature, high-pressure gas. The compressor here is not an ideal compressor; the adiabatic efficiency η should be considered. c and variable efficiency η cp The temperature of the working gas medium rises after exiting the compressor 1 outlet. ( κ is the adiabatic index, π is the compression ratio, and T is the thermal index. 1c1 This indicates the compressor inlet temperature in thermal and cold storage mode. (This indicates the compressor outlet temperature in the thermal and cold storage mode). Then, the gaseous working medium enters the molten salt gas heat exchanger 4, where it exchanges heat with the thermal storage system. This heat exchange between the gaseous working medium and the thermal storage system allows for isobaric heat release of the gaseous working medium. In this embodiment, the thermal storage system includes a low-temperature molten salt tank 5 and a high-temperature molten salt tank 6 connected via a molten salt pump. The heat from the high-temperature gaseous working medium at the compressor 1 outlet is transferred to the low-temperature molten salt in the low-temperature molten salt tank 5, causing the temperature of the high-temperature gaseous working medium to rise from... Reduce to On the other hand, the low-temperature molten salt in low-temperature molten salt tank 5 is heated from a temperature Heated to temperature The gaseous working medium is then pumped into the high-temperature molten salt tank 6. After isobaric heat release and cooling through heat exchange with the heat storage system, it enters turbine 2 for adiabatic expansion to perform work. According to a certain compression ratio π, the high-temperature, high-pressure gaseous working medium is expanded into a low-temperature, normal-pressure gaseous working medium. Since turbine 2 is not an ideal turbine, the adiabatic efficiency η should be considered. t and variable efficiency η tp The temperature of the working gas medium decreases after exiting turbine 2. κ is the adiabatic index, π is the compression ratio of turbine 2, and T 0c1 This indicates the turbine outlet temperature in energy storage mode. (This indicates the turbine inlet temperature in the energy storage mode). The gaseous working medium then enters the carbon dioxide condenser 3, where it exchanges heat with the compressed carbon dioxide in the cold storage system. This heat exchange with the carbon dioxide condenser achieves isobaric heat absorption of the working medium and isobaric heat release of the compressed carbon dioxide. In this embodiment, the cold storage system includes a compressed carbon dioxide storage tank 7 and a cryogenic liquid carbon dioxide storage tank 8 connected to the carbon dioxide condenser 3. The carbon dioxide in the compressed carbon dioxide storage tank 7 is compressed carbon dioxide and is in a gaseous state. After compression, the carbon dioxide's condensation temperature increases, making it easier to condense. Therefore, the compressed carbon dioxide in the compressed carbon dioxide storage tank 7 exchanges heat with the Brayton cycle working medium of the energy storage system (the Brayton cycle working medium absorbs heat, and the carbon dioxide releases heat), achieving isobaric heat release before condensing into liquid carbon dioxide and storing it in the carbon dioxide storage tank. The cryogenic gaseous working medium at the turbine 2 outlet absorbs heat from the compressed carbon dioxide storage tank 7, causing the temperature of the cryogenic gaseous working medium to rise from T... 0c1 Rise to T 1c1 On the other hand, the compressed carbon dioxide, after being cooled, enters the cryogenic liquid carbon dioxide storage tank 8. Subsequently, the gaseous working medium is adiabatically compressed again by the compressor 1 to repeat the above process. In other embodiments, the original gaseous working medium can also be discharged, and the gaseous working medium obtained from the outside can be adiabatically compressed by the compressor 1 to repeat the above process.

[0052] The compressed carbon dioxide is obtained by using surplus electricity to compress ambient temperature and pressure carbon dioxide gas into compressed carbon dioxide using a carbon dioxide compressor 12, which is then stored in a compressed carbon dioxide storage tank 7. Preferably, the heat energy generated during the compression process is stored as heat energy through a heat pump cycle. The compressed carbon dioxide storage tank 7 has a pressure of 6-8 MPa, at which point the boiling point of carbon dioxide is approximately 20°C. Condensation of carbon dioxide can be achieved by absorbing heat from the carbon dioxide. The cryogenic liquid carbon dioxide storage tank 8 has a temperature of approximately -20°C and a pressure of 6-8 MPa. Thus, the heat pump cycle can simultaneously provide cooling and heat storage, absorbing heat from the liquid carbon dioxide for cooling and releasing heat to the molten salt for energy storage. The ambient temperature and pressure carbon dioxide gas can be obtained using carbon capture technology or as waste gas from a power generation mode based on a Brayton cycle or Rankine cycle.

[0053] Therefore, the cold storage system includes a carbon dioxide compressor 12 connected to the compressed carbon dioxide storage tank 7.

[0054] For power generation models based on the Brayton or Rankine cycles, the gaseous working medium of the thermal storage system circulates within the high-temperature heat engine system. During this circulation, it exchanges heat with the thermal storage system to achieve isobaric heat absorption. It then exchanges heat with the carbon dioxide evaporator (i.e., with the cold storage system) to achieve isobaric heat release of the gaseous working medium and isobaric heat absorption of the liquid carbon dioxide. The work done during this circulation is used for power generation. After absorbing heat in the carbon dioxide evaporator, the liquid carbon dioxide vaporizes, expanding its volume by more than 500 times, resulting in high-pressure gaseous carbon dioxide at 20-60 MPa, which also performs work and is used for power generation. The heat exchange between the gaseous working medium and the carbon dioxide evaporator allows the low-temperature heat engine system to absorb heat from the high-temperature heat engine system or the air using the carbon dioxide evaporator.

[0055] like Figure 2 and Figure 3 As shown, the low-temperature heat engine system is a low-temperature Rankine heat engine system. In this system, the cold storage system includes a compressed carbon dioxide storage tank 7 and a low-temperature liquid carbon dioxide storage tank 8 connected via a carbon dioxide condenser 3. The low-temperature liquid carbon dioxide in the low-temperature liquid carbon dioxide storage tank 8 enters the carbon dioxide evaporator 10. The carbon dioxide evaporator 10 needs to absorb heat, but this heat can originate from the heat exchange between the high-temperature heat engine system and the cold storage system during the isobaric heat release process, or it can be from other low-grade heat sources, such as the heat of the air. In this embodiment, in the high-temperature heat engine system, the gaseous working medium transfers heat to the liquid carbon dioxide from the low-temperature liquid carbon dioxide storage tank 8 in the carbon dioxide evaporator 10. After the liquid carbon dioxide absorbs the heat from the gaseous working medium in the high-temperature heat engine system or directly absorbs the heat from the air, it vaporizes into gaseous carbon dioxide. During the vaporization process, the volume of the carbon dioxide expands more than 500 times, resulting in high-pressure gaseous carbon dioxide at 20-60 MPa. High-pressure gaseous carbon dioxide enters the low-temperature heat engine turbine 11 for adiabatic expansion to perform work and generate electricity. The waste gas (i.e., carbon dioxide gas at normal temperature and pressure) is then collected in the carbon dioxide recovery system for energy storage.

[0056] The high-temperature heat engine system is a high-temperature Brayton heat engine system or a high-temperature Rankine heat engine system.

[0057] In this embodiment, as Figure 2 As shown, the high-temperature heat engine system is a high-temperature Brayton heat engine system. In the high-temperature Brayton heat engine system, the gaseous working medium enters the compressor 1 for adiabatic compression. For a given compression ratio π ′ The gaseous working medium is compressed into a high-temperature, high-pressure gas. The compressor used here is not an ideal compressor, and the adiabatic efficiency η must also be considered. c and variable efficiency η cp The temperature of the gas rises after it exits compressor 1. (T0c2 This indicates the inlet temperature of compressor 1 in power generation mode. (This indicates the compressor outlet temperature in power generation mode). Then, the gaseous working medium exchanges heat with the heat storage system to achieve isobaric heat absorption. Specifically, the gaseous working medium enters the molten salt gas heat exchanger 4, which transfers the heat from the high-temperature molten salt in the high-temperature molten salt tank 6 to the gaseous working medium at the compressor 1 outlet, causing the gaseous working medium temperature to rise from... Rise to On the other hand, the temperature is The high-temperature molten salt was cooled to After the gaseous working medium undergoes isobaric heat absorption in the molten salt gas heat exchanger 4, it enters the turbine 2 for adiabatic expansion, performing work on the outside, according to a certain compression ratio π. ′ The high-temperature, high-pressure gas working medium is expanded into a low-temperature, normal-pressure gas working medium. Turbine 2 here is also not an ideal turbine, and the adiabatic efficiency η should also be considered. t and variable efficiency η tp The temperature of the working gas medium decreases after exiting turbine 2. κ is the adiabatic index, π ′ T is the compression ratio of turbine 2. 1c2 This indicates the turbine outlet temperature in power generation mode. The turbine inlet temperature (representing the power generation mode) is still higher than room temperature. In this embodiment, the turbine outlet temperature is generally around 100-200 degrees Celsius. The working gas then enters the carbon dioxide evaporator 10 from the turbine 2 outlet to exchange heat with the cold storage system, performing isobaric heat release. This allows the low-temperature heat engine system to absorb heat from the high-temperature heat engine system using the cold storage system, and to use the cold energy of the cold storage system to perform work and generate electricity. In this embodiment, the working gas at the turbine 2 outlet transfers heat to the liquid carbon dioxide in the carbon dioxide evaporator 10. After isobaric heat release through heat exchange with the cold storage system, the working gas re-enters the compressor to repeat the above steps.

[0058] In other embodiments, the gaseous working medium can also be discharged to the outside after undergoing isobaric heat release through heat exchange with the cold storage system.

[0059] Second embodiment: Heat pump type molten salt-carbon composite energy storage power supply method

[0060] According to the second embodiment of the present invention, the heat pump type molten salt-carbon composite energy storage power supply method is the same as the first embodiment of the present invention in the heat storage and cold storage mode based on the reverse Brayton cycle. In the power generation mode based on the Brayton cycle or Rankine cycle, the gaseous working medium of the heat storage system circulates in the high-temperature heat engine system. During the circulation process, it exchanges heat with the heat storage system to achieve isobaric heat absorption of the working medium, and exchanges heat with the cold storage system to achieve isobaric heat release of the working medium and isobaric heat absorption of liquid carbon dioxide. The work done by the liquid carbon dioxide during the circulation process is used for power generation. After the liquid carbon dioxide absorbs heat through the carbon dioxide evaporator, the liquid carbon dioxide vaporizes and expands in volume by more than 500 times, and obtains high-pressure gaseous carbon dioxide of 20-60 MPa to do work and be used for power generation.

[0061] The difference between the heat pump-type molten salt-carbon composite energy storage and power supply method according to the second embodiment of the present invention and the first embodiment is only that:

[0062] In power generation modes based on the Brayton or Rankine cycle, the high-temperature heat engine system is a high-temperature Rankine heat engine system. The Rankine cycle working medium in the high-temperature Rankine heat engine system includes at least one of water, ammonia solution, and organic solvents such as hydrocarbons, alcohols, ethers, esters, ketones, aldehydes, phenols, carboxylic acids, amines, glycol derivatives, and heterocyclic compounds.

[0063] In this embodiment, as Figure 3 As shown, in the high-temperature Rankine engine system, the liquid Rankine cycle working medium absorbs heat from the heat storage medium in the heat storage system through the working medium evaporator 13. Specifically, the working medium evaporator 13 transfers the heat of the high-temperature molten salt in the high-temperature molten salt tank 6 to the liquid working medium. The working medium evaporator 13 is a special type of molten salt gas heat exchanger. Thus, the liquid Rankine cycle working medium undergoes isobaric heat absorption through heat exchange with the heat storage system via the working medium evaporator 13, becoming a high-temperature, high-pressure steam form of the Rankine cycle working medium. The steam form of the Rankine cycle working medium passes through the superheater 14 and then enters the turbine 15 for adiabatic expansion and work. The exhaust gas from the turbine 15 is cooled by heat exchange in the regenerating heat exchanger 16 and then releases heat at isobaric pressure in the carbon dioxide evaporator 10, condensing into a liquid Rankine cycle working medium. Simultaneously, the liquid carbon dioxide absorbs heat from the Rankine cycle working medium and evaporates into gaseous carbon dioxide. The working fluid pump 18 adiabatically compresses the condensed liquid Rankine cycle working medium and reheats it through the regenerating heat exchanger 16. Then, the liquid Rankine cycle working medium re-enters the working medium evaporator 13, and this cycle repeats continuously. In some other embodiments, the regenerating heat exchanger 16 can be omitted, meaning that steps involving the regenerating heat exchanger 16 can be omitted.

[0064] Therefore, in power generation modes based on the Brayton or Rankine cycles, the gas turbines used in the Brayton cycle are generally coaxial, with the turbine's work exceeding the compressor's energy consumption, resulting in a net power output. Furthermore, carbon dioxide expands rapidly as it changes from liquid to gas, and the waste heat from the turbine outlet is used to heat the liquid carbon dioxide back to a gaseous state, driving the turbine to generate electricity. Simultaneously, the Rankine cycle can also utilize molten salt heat to evaporate water, driving a turbine to generate electricity.

[0065] Third embodiment: A heat pump type molten salt-carbon composite energy storage and power supply device

[0066] Figures 1-3 The present invention illustrates a third embodiment of a heat pump type molten salt-carbon composite energy storage power supply device based on the heat pump type energy storage power supply method described above.

[0067] The heat pump type molten salt-carbon composite energy storage and power supply device corresponds to the heat storage and cold storage mode based on the reverse Brayton cycle. It includes a compressor 1, which is connected in series along the direction of the gas working medium to form a loop, a molten salt gas heat exchanger 4 connected to the heat storage system, a turbine 2, and a carbon dioxide condenser 3 connected to the cold storage system.

[0068] The heat pump type molten salt-carbon composite energy storage power supply device corresponds to a power generation mode based on Brayton cycle or Rankine cycle, which includes a high-temperature heat engine system and a low-temperature heat engine system.

[0069] The high-temperature heat engine system includes a compression device connected in series along the direction of the working gas medium via pipelines, a molten salt gas heat exchange device connected to the heat storage system, a power generation device, and a carbon dioxide evaporator connected to the cold storage system.

[0070] When the high-temperature heat engine system is a high-temperature Brayton heat engine system, the compression device is compressor 1, the power generation device is turbine 2, and the molten salt gas heat exchange device is molten salt gas heat exchanger 4.

[0071] When the high-temperature heat engine system is a high-temperature Rankine heat engine system, the compression device is a working fluid pump 18, the molten salt gas heat exchange device is a working medium evaporator 13, the power generation device is a steam turbine 15, and the high-temperature heat engine system forms a loop.

[0072] The cryogenic heat engine system includes a cryogenic liquid carbon dioxide storage tank 8, a carbon dioxide evaporator 10, a cryogenic heat engine turbine 11, and a carbon dioxide recovery system connected in series. The cryogenic storage system exchanges heat with the gaseous working medium of the high-temperature heat engine system through the carbon dioxide evaporator 10, or directly exchanges heat with air through the carbon dioxide evaporator, to achieve carbon dioxide vaporization. The carbon dioxide recovery system can be a compressed carbon dioxide storage tank 7, or other devices.

[0073] The heat storage medium of the heat storage system is molten salt, and the cold storage medium of the cold storage system is liquid carbon dioxide.

[0074] The carbon dioxide condenser 3 is used for heat exchange between the gas working medium of the high-temperature heat engine system and the low-temperature liquid carbon dioxide, so as to realize the isobaric heat absorption of the gas working medium of the high-temperature heat engine system and the condensation of compressed carbon dioxide.

[0075] In all the above embodiments, the gaseous working medium includes air, argon, nitrogen, helium, or carbon dioxide. The Rankine cycle working medium includes water, ammonia solution, and at least one organic solvent such as hydrocarbons, alcohols, ethers, esters, ketones, aldehydes, phenols, carboxylic acids, amines, glycol derivatives, and heterocyclic compounds.

[0076] The heat storage system includes at least two interconnected heat storage medium insulated containers with different internal heat storage medium temperatures, or at least one interconnected heat storage medium insulated container with a temperature gradient in the internal heat storage medium. The heat storage medium includes one of the following: nitrates, chlorides, and fluorides, which are molten salts that are liquid within the operating temperature range. The carbon dioxide cold storage system includes a carbon dioxide compressor 12, a carbon dioxide condenser 3, and a cryogenic liquid carbon dioxide storage tank 8 connected in sequence. In this embodiment, the compressed carbon dioxide does not need to be directly placed into the storage tank, but is cooled to become liquid compressed carbon dioxide before being placed into the storage tank. Therefore, a compressed carbon dioxide storage tank 7 is not required. In other embodiments, the compressed carbon dioxide storage tank 7 is located between the carbon dioxide compressor 12 and the carbon dioxide condenser 3 for storing compressed carbon dioxide.

[0077] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of the invention. Various variations can be made to the above embodiments of the present invention. That is, all simple and equivalent changes and modifications made based on the claims and description of this invention fall within the protection scope of the claims of this patent. All aspects not described in detail in this invention are conventional technical content.

Claims

1. A heat pump-type molten salt-carbon composite energy storage and power supply method, characterized in that, It includes the following modes: The heat and cold storage mode based on the reverse Brayton cycle: the gas working medium is adiabatically compressed by the compressor, and then exchanges heat with the heat storage system to achieve isobaric heat release of the gas working medium. The heat storage medium of the heat storage system is molten salt, so that heat is stored in the molten salt. Then it enters the turbine for adiabatic expansion to do work. Then, through heat exchange with the carbon dioxide condenser, the gas working medium achieves isobaric heat absorption and isobaric heat release of compressed carbon dioxide. After isobaric heat release, the compressed carbon dioxide is condensed into liquid carbon dioxide and stored in the liquid carbon dioxide storage tank. Then the gas working medium is adiabatically compressed again by the compressor to repeat the above process. Power generation mode based on Brayton cycle or Rankine cycle: The working medium circulates in a high-temperature heat engine system. During the circulation process, it exchanges heat with the heat storage system to achieve isobaric heat absorption of the working medium. It exchanges heat with the carbon dioxide evaporator to achieve isobaric heat release of the working medium and isobaric heat absorption of liquid carbon dioxide. The work done by the working medium during the circulation process is used for power generation. After the liquid carbon dioxide absorbs heat through the carbon dioxide evaporator, it vaporizes. During the vaporization process, the volume of carbon dioxide expands by more than 500 times, and high-pressure gaseous carbon dioxide at 20-60 MPa is obtained to do work and be used for power generation.

2. The heat pump-type molten salt-carbon composite energy storage and power supply method according to claim 1, characterized in that, The high-temperature heat engine system is a high-temperature Brayton heat engine system. In the high-temperature Brayton heat engine system, the gaseous working medium enters the compressor for adiabatic compression, and then exchanges heat with the heat storage system to achieve isobaric heat absorption of the gaseous working medium. Then it enters the turbine for adiabatic expansion to do work, and exchanges heat with the carbon dioxide evaporator to achieve isobaric heat release of the gaseous working medium. Subsequently, the gaseous working medium enters the compressor again to repeat the above steps or is discharged to the outside.

3. The heat pump-type molten salt-carbon composite energy storage and power supply method according to claim 1, characterized in that, The high-temperature heat engine system is a high-temperature Rankine heat engine system. In this system, the liquid Rankine cycle working medium undergoes isobaric heat absorption through heat exchange with the heat storage system via a working medium evaporator, becoming a steam-form Rankine cycle working medium. The steam-form Rankine cycle working medium adiabatically expands and performs work in the turbine, and the exhaust gas releases heat at isobaric pressure in the carbon dioxide evaporator, condensing into a condensed liquid Rankine cycle working medium. Simultaneously, the liquid carbon dioxide absorbs heat from the Rankine cycle working medium and evaporates into gaseous carbon dioxide. Finally, the liquid Rankine cycle working medium is adiabatically compressed by a working fluid pump and re-enters the evaporator to repeat the above steps.

4. The heat pump-type molten salt-carbon composite energy storage and power supply method according to claim 1, characterized in that, The heat exchange between the gaseous working medium and the carbon dioxide evaporator enables the low-temperature heat engine system to absorb heat from the high-temperature heat engine system or the air using the carbon dioxide evaporator. The low-temperature heat engine system is a low-temperature Rankine heat engine system. In the low-temperature Rankine heat engine system, liquid carbon dioxide in the cold storage system enters the carbon dioxide evaporator to absorb heat from the gaseous working medium of the high-temperature heat engine system, or directly absorbs heat from the air, causing the liquid carbon dioxide to absorb heat and vaporize. During the vaporization process, the volume of carbon dioxide expands more than 500 times, resulting in high-pressure gaseous carbon dioxide at 20-60 MPa. The high-pressure gaseous carbon dioxide enters the low-temperature heat engine turbine for adiabatic expansion to perform work for power generation, and then the waste gas is collected.

5. The heat pump-type molten salt-carbon composite energy storage and power supply method according to claim 1, characterized in that, The working gas medium includes air, argon, nitrogen, helium, or carbon dioxide.

6. The heat pump type molten salt-carbon composite energy storage and power supply method according to claim 3, characterized in that, The working medium of the Rankine cycle includes water, ammonia solution, and at least one of hydrocarbons, alcohols, ethers, esters, ketones, aldehydes, phenols, carboxylic acids, amines, glycol derivatives, and heterocyclic compounds.

7. A heat pump type molten salt-carbon composite energy storage and power supply device, characterized in that, It is based on the heat pump energy storage power supply method according to any one of claims 1-6; Corresponding to the heat storage and cold storage mode, it includes a compressor that is connected in series along the direction of the gas working medium to form a loop, a molten salt gas heat exchanger connected to the heat storage system, a turbine, and a carbon dioxide condenser connected to the cold storage system. Corresponding to the power generation mode, it includes high-temperature heat engine systems and low-temperature heat engine systems; The high-temperature heat engine system includes a compression device connected in series along the direction of the working gas medium via pipelines, a molten salt gas heat exchange device connected to the heat storage system, a power generation device, and a carbon dioxide evaporator connected to the cold storage system. When the high-temperature heat engine system is a high-temperature Brayton heat engine system, the compression device is a compressor, the power generation device is a turbine, and the molten salt gas heat exchange device is a molten salt gas heat exchanger. When the high-temperature heat engine system is a high-temperature Rankine heat engine system, the compression device is a working fluid pump, the molten salt gas heat exchange device is a working medium evaporator, the power generation device is a steam turbine, and the high-temperature heat engine system forms a loop. The low-temperature heat engine system includes the cold storage system, the carbon dioxide evaporator, the low-temperature heat engine turbine, and the carbon dioxide recovery system connected in series. The cold storage system exchanges heat with the gas working medium of the high-temperature heat engine system through the carbon dioxide evaporator, or exchanges heat directly with the air through the carbon dioxide evaporator. The heat storage medium of the heat storage system is molten salt, and the cold storage medium of the cold storage system is carbon dioxide.

8. The heat pump type molten salt-carbon composite energy storage and power supply device according to claim 7, characterized in that, The carbon dioxide condenser is used for heat exchange between the gas working medium and compressed carbon dioxide in the heat storage and cold storage mode, so as to achieve isobaric heat absorption of the gas working medium in the heat storage and cold storage mode, and at the same time realize the condensation of compressed carbon dioxide.

9. The heat pump type molten salt-carbon composite energy storage and power supply device according to claim 7, characterized in that, The heat storage system includes at least two interconnected heat storage medium insulation containers with different internal heat storage medium temperatures, or at least one interconnected heat storage medium insulation container with an inclined temperature layer having a temperature gradient in its internal heat storage medium.

10. The heat pump type molten salt-carbon composite energy storage and power supply device according to claim 7, characterized in that, The cold storage system includes a carbon dioxide compressor, a carbon dioxide condenser, and a liquid carbon dioxide storage tank connected in sequence.

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