A system and method for high-temperature energy storage and air separation for s-CO2 cycle power generation under oxygen-enriched combustion

Abstract

The present invention discloses a high-temperature energy storage and air separation system for s-CO2 cycle power generation under oxygen-enriched combustion and a method thereof, comprising a heat storage and release and air separation subsystem and a cycle power generation subsystem; the heat storage and release and air separation subsystem comprises a heat storage reactor, a heat exchanger, an oxygen storage tank, a nitrogen storage tank and a heat exchange and heat storage tank; the cycle power generation subsystem comprises an oxygen-enriched combustion unit and a supercritical CO2 Brayton cycle power generation unit; the oxygen-enriched combustion unit comprises an oxygen storage tank, a combustion chamber, a denitrification device, a dust collector, a desulfurization device, a compression and purification device and a CO2 capture device; the supercritical CO2 Brayton cycle power generation unit comprises a turbine unit, a regenerator, a generator, a condenser and a compressor; the present invention matches a novel heat storage and energy storage and air separation technology with a supercritical CO2 cycle power generation system under oxygen-enriched combustion, forming a power generation system design scheme that can realize self-supply of oxygen, CO2 separation and high system efficiency.

Description

Technical Field

[0001] The present invention relates to the technical field of high-temperature thermal energy storage and air separation, and in particular to a system and method for high-temperature energy storage and air separation for s-CO2 cycle power generation under oxygen-enriched combustion, which can be applied to fields such as solar / wind power generation grid connection and power grid peak shaving and valley filling. Background Art

[0002] Coal-fired power generation faces serious challenges, including poor power supply and demand matching, difficulty absorbing off-peak electricity, and high CO2 emissions. Furthermore, the intermittent and unstable nature of renewable energy generation prevents direct grid connection. To address these issues, the development of new low-carbon power generation and energy storage technologies is urgently needed.

[0003] Oxygen-enriched combustion technology increases the CO2 concentration in the flue gas by using high-purity oxygen instead of air as a combustion aid, which facilitates the capture and storage of CO2. Supercritical CO2 (s-CO2) cycle power generation technology utilizes the unique physical properties of CO2 in the supercritical state to achieve efficient heat-to-power conversion, with the advantages of small size, high efficiency and low pollution. The oxygen-enriched combustion combined with the supercritical CO2 cycle power generation system combines the high-concentration CO2 emission advantages of oxygen-enriched combustion and the high thermal efficiency characteristics of the s-CO2 cycle. However, oxygen-enriched combustion requires high-purity oxygen, and the current conventional deep-cold liquefied oxygen production technology has high energy consumption. In large-scale applications, the energy consumption of oxygen production will offset part of the efficiency improvement brought by oxygen-enriched combustion.

[0004] Efficient energy storage technology is an effective solution for addressing issues such as power grid peak-valley variations and renewable energy integration. Among the many energy storage technologies under development, phase change thermal energy storage and thermochemical thermal energy storage are increasingly being adopted in energy storage and power generation systems due to their advantages, such as high heat storage density and low heat loss. Among existing high-temperature thermal energy storage and power generation systems, the most mature technology uses nitrates as the sensible heat molten salt heat storage medium. However, nitrate materials are limited to a maximum temperature of 560°C, which reduces overall power generation efficiency and prevents coupling with supercritical CO2 generators. On the other hand, using metals and their alloys as phase change thermal storage materials for thermal energy storage offers high operating temperatures and heat storage densities. However, metals are prone to leakage during the phase change process and are subject to high corrosion and material deactivation at high temperatures, necessitating encapsulation techniques. However, composite phase change materials encapsulated with inert materials exhibit reduced heat storage density compared to pure phase change materials, limiting their application. On the other hand, chemical chaining thermochemical thermal energy storage (CL-TES) technology within thermochemical energy storage utilizes oxygen carrier materials to store and release heat during redox reactions. In this technology, the oxygen carrier selectively absorbs and releases oxygen under pressure or temperature fluctuations to produce pure oxygen and nitrogen to achieve air separation. At the same time, it can store and release chemical reaction heat. The reaction is shown below, where Me xO y 、Me x O y-1 They represent oxygen-rich oxygen carrier and oxygen-poor oxygen carrier respectively.

[0005]

[0006] The oxygen storage and release process of oxygen carriers is a typical gas-solid reaction. Its slow reaction kinetics are a major limitation to its application, primarily due to the slow reaction and diffusion rate of gases in solid materials. When oxygen carrier materials are formed into large particles and applied to fixed-bed reactors, a considerable portion of the oxygen carrier material within the particles is unable to rapidly participate in the redox reaction, resulting in an incomplete reaction and, in turn, reduced overall efficiency.

[0007] Therefore, it is crucial to couple oxygen carrier thermochemical energy storage materials with metal phase change materials with high thermal storage density, develop a composite energy storage medium with high thermal storage density, and match it with an oxygen-enriched combustion combined supercritical CO2 cycle power generation system to construct a power generation system design that can achieve self-supply of oxygen, CO2 separation, and high system efficiency. Summary of the Invention

[0008] The technical problem to be solved by the present invention is to address the shortcomings of the above-mentioned existing technologies and provide a system and method for high-temperature energy storage and air separation for s-CO2 cycle power generation under oxygen-enriched combustion. This system and method for high-temperature energy storage and air separation for s-CO2 cycle power generation under oxygen-enriched combustion couples oxygen-carrier thermochemical energy storage materials with high thermal storage density metal phase change materials to develop a composite energy storage medium with high thermal storage density. This not only ensures that the oxygen-carrier thermochemical material has a short gas diffusion path and rapid reaction effect, but also solves the problem of metal phase change material packaging, achieving the complementary advantages of thermochemical thermal energy storage and phase change thermal energy storage, and simultaneously achieving air separation to provide oxygen for oxygen-enriched combustion. This new thermal energy storage and air separation technology is matched with an oxygen-enriched combustion combined supercritical CO2 cycle power generation system, forming a power generation system design that can achieve self-supply of oxygen, CO2 separation, and high system efficiency. The present invention is a brand-new composite thermal energy storage and air separation technology coupled with a new power generation technology system solution, which will greatly promote efficient energy utilization and energy conservation and emission reduction.

[0009] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0010] A high-temperature energy storage and air separation system for s-CO2 cycle power generation under oxygen-enriched combustion, comprising a heat storage and release and air separation subsystem and a cycle power generation subsystem; the heat storage and release and air separation subsystem comprises a primary heat storage reactor, a secondary heat storage reactor, a first heat exchanger, an oxygen storage tank, a nitrogen storage tank, a second heat exchanger, a heat exchange storage tank, a third heat exchanger and a fourth heat exchanger; an electric heating device and a first composite energy storage medium are arranged in the primary heat storage reactor; the secondary heat storage reactor is connected to the primary heat storage reactor through a pump, and a second composite energy storage medium is arranged in the secondary heat storage reactor; the first heat exchanger is connected to the secondary heat storage reactor through a pump and a compressor; the nitrogen storage tank is connected to the first heat exchanger; the oxygen storage tank is connected to the first heat exchanger; the second heat exchanger is connected to the oxygen storage tank; the heat exchange storage tank is connected to the first heat exchanger and the second heat exchanger; the third heat exchanger is connected to the heat exchange storage tank and is connected to the secondary heat storage reactor through a pump; the fourth heat exchanger is connected to the It is connected to the first-level heat storage reactor and connected to the first heat exchanger through a compressor; the cycle power generation subsystem includes an oxygen-enriched combustion unit and a supercritical CO2 Brayton cycle power generation unit; the oxygen-enriched combustion unit includes an oxygen storage tank, a combustion chamber, a denitrification device, a dust collector, a desulfurization device, a compression purification device and a CO2 capture device; the oxygen storage tank is connected to the combustion chamber through a second heat exchanger and a pump, and the combustion chamber, the denitrification device, the dust collector, the desulfurization device, the compression purification device and the CO2 capture device are connected in sequence; the supercritical CO2 Brayton cycle power generation unit includes a fourth heat exchanger, a turbine unit, a regenerator, a generator, a condenser, a compressor and a combustion chamber; the fourth heat exchanger is connected to the turbine unit; the turbine unit is connected to the regenerator; the turbine unit is connected to the generator; the regenerator is connected to the condenser, the condenser is connected to the compressor, and the compressor is connected to the regenerator; the regenerator is connected to the fourth heat exchanger and the combustion chamber through a three-way valve; the combustion chamber is connected to the turbine unit.

[0011] Preferably, both the primary heat storage reactor and the secondary heat storage reactor are axially insulated fixed-bed reactors, comprising a heat storage reactor shell, an insulation layer, upper and lower inlets and outlets, and corresponding two-way valves; the heat storage reactor shell is made of a high-temperature resistant alloy material, and the shell has good sealing performance; the heat storage reactor is equipped with upper and lower cut-off partitions, and an electric heating device and several support plates are placed between the upper and lower cut-off partitions, and holes are left on the support plates for gas circulation; the insulation layer is a high-temperature refractory insulation material, which is wrapped and filled inside the primary heat storage reactor and the secondary heat storage reactor body.

[0012] Preferably, the oxygen storage tank and the nitrogen storage tank share the first heat exchanger and the heat exchange and heat storage tank, and the gas flow direction is controlled by a two-way valve.

[0013] Preferably, the heat storage medium in the heat exchange storage tank is one or more of molten salt sensible heat or phase change heat storage material, high temperature heat transfer oil sensible heat storage material or metal phase change material, and its operating temperature is 200-500°C.

[0014] Preferably, the first composite energy storage medium and the second composite energy storage medium are spherical composite capsules formed by oxygen carrier-coated phase change material, wherein the shell of the capsule is oxygen carrier material and the core of the capsule is metal phase change material.

[0015] Preferably, the diameter of the composite capsule is 3 mm to 50 mm, the shell thickness is 0.5 mm to 10 mm, and the core diameter is 2 mm to 40 mm.

[0016] Preferably, the heat storage temperature range of the first composite energy storage medium is 600°C-1000°C; the oxygen carrier material of the shell of the first composite energy storage medium is BaCoO with an oxygen storage / release temperature of 600°C-1000°C. 3-δ 、LaMnO 3-δ 、SrCoO 3-δ 、SrFeO 3-δ , Co3O4, NiFe2O4, MnFe2O4, CaFe x Mn 1-x O 3-δ One or more metal oxide-based oxygen carriers; the core metal phase change material of the first composite energy storage medium is one or more aluminum-based and copper-based alloys with a phase change temperature of 600°C-1000°C; the optimized combination scheme of the oxygen carrier and the metal phase change material is that the oxygen storage / release temperature of the oxygen carrier differs from the melting point of the metal phase change material by less than 200°C.

[0017] Preferably, the heat storage temperature range of the second composite energy storage medium is 400°C-700°C; the shell oxygen carrier material of the second composite energy storage medium is Ca2AlMnO with an oxygen storage / release temperature between 400°C-700°C. 5+δ and its derivative materials Ca 1.2 Sr 0.8 AlMnO 5+δ 、Ca(Al 1-x Ga x )MnO 5+δ 、Ca2Al(Mn 1-x Co x )O 5+δ One or more oxygen carrier materials; the core metal phase change material of the second composite energy storage medium is one or more aluminum-based alloys with a phase change temperature between 400°C and 700°C; the optimized combination scheme of the oxygen carrier and the metal phase change material is that the oxygen storage / release temperature of the oxygen carrier differs from the melting point of the metal phase change material by less than 150°C.

[0018] A method for operating high-temperature energy storage and air separation for s-CO2 cycle power generation under oxygen-enriched combustion. When the system performs energy storage, surplus electricity from the grid, wind power, photovoltaic power, etc. is used to heat a first composite energy storage medium composed of an oxygen carrier and a phase change material in a first-stage heat storage reactor through an electric heating device for first-stage heat storage. During the heating process, the first composite energy storage medium stores heat in a comprehensive form of thermochemical, latent, and sensible heat. The oxygen carrier in an oxygen-enriched state undergoes a thermochemical reduction reaction to absorb heat and release oxygen, and the phase change material melts to undergo a solid-liquid phase change to store heat in the form of latent heat. The temperatures of the two parts of the material rise while sensible heat storage is performed. The high-temperature oxygen released from the first-stage heat storage reactor is extracted by a pump and introduced into the second-stage heat storage. Reactor; a second composite energy storage medium composed of an oxygen carrier and a phase change material is arranged in the secondary heat storage reactor, which absorbs the heat of high-temperature oxygen and performs the second-stage heat storage in a comprehensive form of thermochemical, latent heat and sensible heat; the oxygen carrier part in the oxygen-rich state undergoes a thermochemical reduction reaction to absorb heat and release oxygen, and the phase change material part undergoes a melting phase change to store heat in the form of latent heat, and the temperature of the two parts of the material rises while performing sensible heat storage; the oxygen released in the secondary heat storage reactor is extracted by a pump, compressed by a compressor, and the surplus heat in the compressed oxygen is stored in the heat exchange storage tank by the first heat exchanger for the third-stage heat storage, and the compressed oxygen is stored in the oxygen storage tank; the oxygen in the oxygen storage tank is used as the oxygen for the oxygen-enriched combustion unit in the cycle power generation system When the air comes from the heat source, the second heat exchanger is used to exchange the heat in the heat exchange storage tank for preheating, and then it is introduced into the circulating power generation subsystem through a pump; when the heat release system is used to release energy, the outside air is preheated by the third heat exchanger and then pumped into the secondary heat storage reactor through a pump. At this time, the oxygen carrier in the oxygen-deficient state in the second composite energy storage medium undergoes a thermochemical oxidation reaction with the air, absorbing oxygen in the air while releasing chemical heat, and the phase change material partially undergoes a solidification phase change to release latent heat; then, the nitrogen-rich gas flowing out of the secondary heat storage reactor is introduced into the primary heat storage reactor through a pump, and the oxygen carrier in the oxygen-deficient state in the first composite energy storage medium undergoes a thermochemical oxidation reaction with the nitrogen-rich gas to further absorb oxygen while releasing chemical heat. The material undergoes a solidification phase change and releases latent heat; the high-temperature nitrogen flowing out of the first-level heat storage reactor is pumped through the fourth heat exchanger to release the high-temperature heat energy to the working fluid of the circulating power generation system; the nitrogen after heat exchange is compressed by the compressor, and the excess heat in the compressed nitrogen is stored in the heat exchange and storage tank through the first heat exchanger, and then stored in the nitrogen storage tank for use in other nitrogen-using industries such as synthetic ammonia; the oxygen and circulating flue gas from the heat storage system are introduced into the combustion chamber of the oxygen-enriched combustion unit to participate in combustion, and the combustion chamber serves as a heat source to provide heat for the supercritical CO2 cycle; the flue gas generated by combustion passes through the denitrification device and the dust collector, and a part of it is pumped to form circulating flue gas and introduced into the combustion chamber to participate in combustion, and the remaining flue gas passes through the desulfurization device and the compression and purification device and is captured by the CO2 capture device;The supercritical CO2 cycle power generation system uses heated CO2 as a turbine to generate power. After the power is generated, the working fluid passes through a regenerator, condenser, and compressor, and is then transported to the combustion chamber of the oxygen-enriched combustion unit and flows through a heat exchanger to be heated before participating in the cycle. The cycle power generation subsystem operates in peak-shaving mode according to the load characteristics and peak-valley differences of the power system. Specifically, it includes two operating modes: the oxygen-enriched combustion unit operates alone; and the heat release unit operates in conjunction with the oxygen-enriched combustion unit. During valley power consumption, the oxygen-enriched combustion unit operates alone, and the combustion chamber uses pure oxygen from the oxygen storage tank and recycled flue gas for oxygen-enriched combustion. The s-CO2 circulating working fluid flows through the combustion chamber through a three-way valve for heat exchange. After heat exchange, the working fluid flows into the turbine unit for turbine power generation. Excess valley power and wind / photovoltaic power are heated and stored in the heat storage unit. During peak power consumption, the heat release unit operates in conjunction with the oxygen-enriched combustion unit. The s-CO2 circulating working fluid is diverted through a three-way valve to exchange heat in the heat storage unit and the combustion chamber. After heat exchange, the working fluid flows into the turbine unit for turbine power generation.

[0019] The present invention has the following beneficial effects:

[0020] 1. Taking into account the advantages and disadvantages of thermochemical energy storage and phase change energy storage, an improved composite energy storage material was proposed. Based on the existing encapsulated phase change capsule, the oxygen carrier-thermochemical reaction layer replaces the phase change capsule's sensible heat shell. This ensures a shorter gas diffusion path for the thermochemical material, increases the heat storage capacity of the phase change thermal storage capsule, and achieves a complementary advantage between thermochemical and phase change energy storage.

[0021] 2. Multi-stage heat storage is achieved through a two-stage reactor and a heat exchange storage tank, which improves the heat storage efficiency and the economy of the overall system.

[0022] 3. The reversible redox reaction of the oxygen carrier is used to achieve air separation function, produce oxygen and nitrogen, and reduce the cost of oxygen / nitrogen production.

[0023] 4. Utilizing an oxygen-enriched combustion combined with a supercritical CO2 cycle power generation system, the oxygen-enriched combustion unit utilizes pure oxygen generated from an oxygen carrier and recycled flue gas for oxygen-enriched combustion, achieving CO2 separation and capture. Because the oxygen is preheated through a heat exchanger and heat storage tank, the inlet temperature of the combustion chamber is increased, further enhancing combustion efficiency.

[0024] 5. The supercritical CO2 cycle unit uses CO2 as the working fluid to generate electricity. It is non-toxic and non-flammable, has good flow and heat transfer characteristics, and its power generation efficiency is higher than that of the conventional Rankine steam cycle. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a schematic diagram of the structure of a high-temperature energy storage and air separation system for s-CO2 cycle power generation under oxygen-enriched combustion in the present invention;

[0026] Figure 2is a schematic diagram of a composite energy storage medium according to an embodiment of the present invention;

[0027] Figure 3 This is a schematic diagram of preparing a composite energy storage medium according to an embodiment of the present invention;

[0028] Figure 4 These are pictures of the composite capsules, phase change capsules, and pure oxygen carrier spheres in different stages of preparation according to the present invention;

[0029] Figure 5 It is Ca2AlMnO 5+δ TG-DSC curve diagram;

[0030] Figure 6 is the DSC curve of the metal core Al;

[0031] Figure 7 It is SrFeO3- δ TG-DTG curve diagram under high temperature conditions;

[0032] Figure 8 This is a comparison chart of heat storage of ceramic balls, thermochemical balls, Al@Al2O3, and Al@CAMO of the same size in the embodiment of the present invention;

[0033] Figure 9 This is a comparison chart of heat storage of ceramic balls, thermochemical balls, Cu56-Si27-Mg17@Al2O3, and Cu56-Si27-Mg17@SFO of the same size in the embodiment of the present invention;

[0034] These include: 1. Primary heat storage reactor; 2. Electric heating equipment; 3. First composite energy storage medium; 4. Secondary heat storage reactor; 5. Second composite energy storage medium; 6. First heat exchanger; 7. Oxygen storage tank; 8. Nitrogen storage tank; 9. Second heat exchanger; 10. Heat exchange and heat storage tank; 11. Third heat exchanger; 12. Fourth heat exchanger; 13. First valve; 14. Second valve; 15. Third valve; 16. Combustion chamber; 17. Denitrification device; 18. Dust collector; 19. Desulfurization device; 20. Compression and purification device; 21. CO2 capture device; 22. Turbine unit; 23. Regenerator; 24. Generator; 25. Condenser; 26. Compressor; 27. Fourth valve; 28. Fifth valve; 29. ​​Sixth valve. DETAILED DESCRIPTION

[0035] The present invention will be further described in detail below with reference to the accompanying drawings and specific preferred embodiments.

[0036] like Figures 1 to 9 As shown, a high-temperature energy storage and air separation system for s-CO2 cycle power generation under oxygen-enriched combustion includes a heat storage and release and air separation subsystem and a cycle power generation subsystem.

[0037] The heat storage and release and air separation subsystem includes a primary heat storage reactor 1, a secondary heat storage reactor 4, a first heat exchanger 6, an oxygen storage tank 7, a nitrogen storage tank 8, a second heat exchanger 9, a heat exchange and heat storage tank 10, a third heat exchanger 11, and a fourth heat exchanger 12. By utilizing the two-stage reactor and the composite energy storage medium placed within it, the heat storage and release and air separation subsystem achieves cascade heat storage and air separation functions, generating high-purity oxygen and nitrogen, and improving the system's energy utilization and economic benefits.

[0038] An electric heating device 2 and a first composite energy storage medium 3 are arranged in the first-level heat storage reactor 1; the electric heating device 2 is placed inside the first-level heat storage reactor 1, and consumes valley electricity from the grid or surplus electricity such as wind power and photovoltaic power to heat the first composite energy storage medium 3.

[0039] The secondary heat storage reactor 4 is connected to the primary heat storage reactor 1 via a pump. Specifically, the b2 outlet of the primary heat storage reactor 1 is connected to the B1 inlet of the secondary heat storage reactor 4 via a pump, for transporting the high-temperature oxygen generated in the primary heat storage reactor 1. The A2 outlet of the secondary heat storage reactor 4 is connected to the a1 inlet of the primary heat storage reactor 1 via a pump, for transporting the nitrogen-rich gas generated after flowing through the secondary heat storage reactor 4. A second composite energy storage medium 5 is disposed within the secondary heat storage reactor 4.

[0040] Preferably, both the primary and secondary heat storage reactors 1 and 4 are axially adiabatic fixed-bed reactors, comprising a heat storage reactor shell, an insulation layer, upper and lower inlets and outlets, and corresponding two-way valves. The shell is made of a high-temperature-resistant alloy and has good sealing properties. The reactors are equipped with upper and lower cutoff baffles, between which an electric heating device 2 and several support plates are placed. The support plates have apertures for gas circulation, and the apertures are smaller than the first composite energy storage medium 3 or the second composite energy storage medium 5. The first composite energy storage medium 3 or the second composite energy storage medium 5 is stacked freely or in an orderly manner on the support plates. The insulation layer is a high-temperature refractory insulation material, which is wrapped and filled inside the primary and secondary heat storage reactors 1 and 4 to reduce heat loss in the heat storage reactors.

[0041] Preferably, the first composite energy storage medium 3 and the second composite energy storage medium 5 are spherical composite capsules formed by oxygen carrier-coated phase change materials, wherein the shell of the capsule is the oxygen carrier material and the core of the capsule is the metal phase change material. Compared with the existing ceramic capsules, thermochemical particles and other multi-shell encapsulated capsules, the present composite capsule has a simple structure, with only an oxygen carrier encapsulation shell layer, and the composite capsule has excellent heat storage capacity and also has air separation function. The schematic diagram of the composite capsule structure is shown in FIG. Figure 2As shown in the figure, an oxygen carrier is coupled with a high-temperature phase change capsule to create a composite energy storage capsule with an oxygen carrier outer layer and a phase change material core. The outermost layer of the capsule particle is the oxygen carrier, ensuring a short gas diffusion path, ensuring smooth oxygen carrier air separation reaction and thermochemical heat storage. The core, on the other hand, uses a highly thermally conductive metal material for phase change heat storage, providing high heat storage density while being unaffected by the diffusion path.

[0042] The first composite energy storage medium uses SrFeO as the oxygen carrier 3-δ , for example, a composite capsule of Cu56-Si27-Mg17 alloy with a core of 3.5 mm, in which the paraffin layer is 0.5, and the final size is recorded as 3.5@0.5@2 mm. The second composite energy storage medium is composed of an oxygen carrier of Ca2AlMnO 5+δ Take the composite capsule with Al core of 5mm as an example, where the paraffin layer is 0.25, the final size is recorded as 5@0.25@2mm.

[0043] The preparation process of composite capsules is as follows Figure 3 As shown, first, paraffin is heated and melted, and a metal ball is placed in the paraffin melt to form a paraffin coating. Secondly, the capsule shell embryo is obtained by mixing the binder gel and the oxygen carrier powder in proportion. Finally, the shell embryo is coated on the metal ball@paraffin layer to form a composite capsule precursor. The precursor is dried at room temperature and then pre-burned in a muffle furnace to remove the paraffin layer and organic binder. During this process, the paraffin will be decomposed into gas, thereby forming a cavity layer between the outer shell and the inner aluminum ball. At the same time, the binder will be completely decomposed in this process. The pre-burned sample is further transferred to a tubular furnace for high-temperature calcination to finally obtain the required composite capsule sample. It is worth noting that the cavity layer is indispensable. It provides a buffer space for the thermal contraction of the shell and the thermal expansion of the core, increases the stability of the composite capsule, and prevents the capsule shell from breaking.

[0044] Phase change capsules were prepared using the same method. The samples in each process were as follows. Figure 4 The same method was used to form a mixture of oxygen carrier powder and binder gel into spheres of the same size. A heat storage test was conducted, and the calculation formula is as follows:

[0045]

[0046] Among them C shell and C core are the specific heat capacities of the shell and the Al core, respectively, which can be obtained by querying the thermodynamic software. shell and m core Represent the mass of the shell and the aluminum core respectively. The calculated temperature range is t1 is the initial temperature, t2 is the final temperature, ΔH redis the reduction reaction enthalpy of the oxygen carrier, and Lm is the latent heat of the metal core. In this example, the latent heat of fusion of the Al core is 396.6 J / g; the latent heat of fusion of the Cu56-Si27-Mg17 core is 422.8 J / g.

[0047] The heat storage of samples of the same size in different temperature ranges is as follows: Figure 8 and Figure 9 As shown, it can be found that the heat storage density of the composite capsule is the highest.

[0048] Preferably, the composite capsule has a diameter of 3mm-50mm, a shell thickness of 0.5mm-10mm, and a core diameter of 2mm-40mm. To ensure the composite energy storage medium remains stable and does not crack during cyclic use, a gap is left between the metal phase change material core and the oxygen carrier shell during the molding process to buffer the volume change of the core phase change material during cyclic use.

[0049] Preferably, the heat storage temperature range of the first composite energy storage medium 3 is 600°C-1000°C; the oxygen carrier material of the shell of the first composite energy storage medium 3 is BaCoO with an oxygen storage / release temperature of 600°C-1000°C. 3-δ 、LaMnO 3-δ 、SrCoO 3-δ 、SrFeO 3-δ , Co3O4, NiFe2O4, MnFe2O4, CaFe x Mn 1-x O 3-δ The core metal phase change material of the first composite energy storage medium 3 is one or more of aluminum-based and copper-based alloys with a phase change temperature of 600°C-1000°C; the optimized combination of the oxygen carrier and the metal phase change material is that the difference between the oxygen storage / release temperature of the oxygen carrier and the melting point of the metal phase change material is less than 200°C. For example, the oxygen carrier is BaCoO 3-δ (Redox temperature is 700℃-1000℃), the metal phase change material is Cu80-Si20 alloy (melting point is 803℃); the oxygen carrier is SrFeO 3-δ (Redox temperature is 600℃-950℃), the metal phase change material is Cu56-Si27-Mg17 alloy (melting point is 770℃); the oxygen carrier is CaFe x Mn 1-x O 3-δ (oxidation-reduction temperature is 700℃-900℃), the metal phase change material is Cu74-Zn19-Si7 (melting point is 765℃); the oxygen carrier is Co3O4 (oxidation-reduction temperature is 800℃-950℃), and the metal phase change material is Al40-Si45-Fe15 alloy (melting point is 869℃).

[0050] Preferably, the heat storage temperature range of the second composite energy storage medium 5 is 400°C-700°C; the oxygen carrier material of the shell of the second composite energy storage medium 5 is Ca2AlMnO with an oxygen storage / release temperature between 400°C-700°C. 5+δ and its derivative materials Ca 1.2 Sr 0.8 AlMnO 5+δ 、Ca(Al 1-x Ga x )MnO 5+δ 、Ca2Al(Mn 1-x Co x )O 5+δ One or more oxygen carrier materials; the core metal phase change material of the second composite energy storage medium 5 is one or more aluminum-based alloys with a phase change temperature between 400°C and 700°C; the optimized combination of the oxygen carrier and the metal phase change material is that the difference between the oxygen storage / release temperature of the oxygen carrier and the melting point of the metal phase change material is less than 150°C. For example, the oxygen carrier is Ca2AlMnO 5+δ (oxidation-reduction temperature is 540℃-700℃), the metal phase change material is pure aluminum (melting point is 660℃); the oxygen carrier is Ca(Al 1-x Ga x )MnO 5+δ (Redox temperature is 450℃-700℃), the metal phase change material is binary aluminum silicon alloy Al-25Si (melting point is 577℃); the oxygen carrier is Ca2AlMn 0.95 Co 0.05 O 5+δ (Redox temperature is 539℃-605℃), and the metal phase change material is ternary aluminum-silicon alloy Al65-Cu30-Si5 (melting point is 548℃).

[0051] The first heat exchanger 6 is connected to the B2 outlet of the secondary heat storage reactor 4 through a pump and a compressor 26; the inlet of the nitrogen storage tank 8 is connected to the first heat exchanger 6, and the outlet of the nitrogen storage tank 8 is connected to a nitrogen-using industry such as synthetic ammonia; the inlet of the oxygen storage tank 7 is connected to the first heat exchanger 6; the second heat exchanger 9 is connected to the outlet of the oxygen storage tank 7; the heat exchange storage tank 10 is connected to the first heat exchanger 6 and the second heat exchanger 9; the oxygen storage tank 7 and the heat exchange storage tank 10 are used to store compressed oxygen and waste heat, respectively. The third heat exchanger 11 is connected to the heat exchange and storage tank 10 and, via a pump, to the A1 inlet of the secondary heat storage reactor 4. The third heat exchanger 11 is connected to the outside air and is used to introduce preheated cold air into the secondary heat storage reactor 4. The fourth heat exchanger 12 is connected to the a2 outlet of the primary heat storage reactor 1 via a pump and is used to exchange heat from the high-temperature nitrogen after passing through the primary heat storage reactor 1 for the circulating power generation subsystem. The fourth heat exchanger 12 is connected to the first heat exchanger 6 via a compressor and is also connected to the a2 outlet of the primary heat storage reactor 1 via a pump. The nitrogen after heat exchange is connected to the first heat exchanger 6, the nitrogen storage tank 8, and the heat exchange and storage tank 10 through the compressor, for storing the compressed nitrogen and waste heat.

[0052] Preferably, the oxygen storage tank 7 and the nitrogen storage tank 8 share the first heat exchanger 6 and the heat exchange storage tank 10, and the gas flow direction is controlled by a two-way valve. During the heat storage process, the first valve 13 is closed and the second valve 14 is opened, and the oxygen and waste heat are stored in the oxygen storage tank 7 and the heat exchange storage tank 10 respectively; during the heat release process, the second valve 14 is closed and the first valve 13 is opened, and the nitrogen and waste heat are stored in the nitrogen storage tank 8 and the heat exchange storage tank 10 respectively; at the same time, the third valve 15 is opened, and the air is pumped through the third heat exchanger 11 to exchange for the heat of the heat exchange storage tank 10 for preheating. Preferably, the heat storage medium in the heat exchange storage tank 10 is one or more of molten salt sensible heat or phase change heat storage material, high-temperature heat transfer oil sensible heat storage material or metal phase change material, and its operating temperature is 200-500°C.

[0053] The cycle power generation subsystem includes an oxygen-enriched combustion unit and a supercritical CO2 Brayton cycle power generation unit; the oxygen-enriched combustion unit includes an oxygen storage tank 7, a combustion chamber 16, a denitrification device 17, a dust collector 18, a desulfurization device 19, a compression purification device 20 and a CO2 capture device 21; the oxygen storage tank 7 is connected to the combustion chamber 16 via the second heat exchanger 9 and the pump, and the combustion chamber 16 is connected to the oxygen storage tank 7 and the circulating flue gas through the pump, which is used to absorb the preheated oxygen from the heat storage and release and air separation subsystem and the waste heat flue gas that has been dust-removed; the combustion chamber 16, the denitrification device 17, the dust collector 18, the desulfurization device 19, the compression purification device 20 and the CO2 capture device 21 are connected in sequence, and the flue gas generated in the combustion chamber 16 passes through the denitrification device 17, the dust collector 18, the desulfurization device 19, the compression purification device 20 in sequence and is captured by the CO2 capture device 21; the supercritical CO2 Brayton cycle power generation subsystem includes an oxygen-enriched combustion unit 7, a combustion chamber 16, a denitrification device 17, a dust collector 18, a desulfurization device 19, a compression purification device 20 and a ...1 The Dunn cycle power generation unit includes a fourth heat exchanger 12, a turbine unit 22, a regenerator 23, a generator 24, a condenser 25, a compressor 26 and a combustion chamber 16; the fourth heat exchanger 12 is connected to the turbine unit 22, and the turbine unit 22 uses the working fluid after heat exchange in the fourth heat exchanger 12 or the working fluid heated by the combustion chamber 16 to perform work; the turbine unit 22 is connected to the regenerator 23, and the regenerator 23 uses the waste heat of the working fluid after performing work to heat the working fluid after condensation and compression; the turbine unit 22 is connected to the generator 24, and the generator 24 is used to generate electricity; the regenerator 23 is connected to the condenser 25, and the condenser 25 is used to condense the working fluid flowing out of the regenerator 23, the condenser 25 is connected to the compressor 26, and the compressor 26 is connected to the regenerator 23; the regenerator 23 is connected to the fourth heat exchanger 12 and the combustion chamber 16 through a three-way valve; the combustion chamber 16 is connected to the turbine unit 22. The compressor 26 is used to compress the working fluid that passes through the condenser 25 and enter the regenerator 23. The working fluid that passes through the regenerator 23 obtains enough heat through the heat exchanger and the combustion chamber 16 and then enters the turbine unit 22 to perform work.

[0054] When the oxygen-enriched combustion unit of the circulating power generation subsystem uses the oxygen separated and stored in the heat storage and release and air separation subsystem, the fourth valve 27, the fifth valve 28 and the sixth valve 29 are opened, and the oxygen in the oxygen storage tank 7 is preheated by exchanging heat in the heat exchange and storage unit through the second heat exchanger 9, and then transported to the combustion chamber 16 through the pump.

[0055] A method for operating high-temperature energy storage and air separation for s-CO2 cycle power generation under oxygen-rich combustion. When the system performs energy storage, the grid off-peak electricity or surplus electricity such as wind power and photovoltaic power is used through an electric heating device 2 to heat the first composite energy storage medium 3 composed of an oxygen carrier and a phase change material in the first heat storage reactor 1 for first-stage heat storage. During the heating process, the first composite energy storage medium 3 stores heat in a comprehensive form of thermochemistry, latent heat, and sensible heat. The oxygen carrier in the oxygen-rich state undergoes a thermochemical reduction reaction to absorb heat and release oxygen, and the phase change material melts to undergo a solid-liquid phase change to store heat in the form of latent heat. The temperature of the two parts of the material rises while sensible heat storage is performed simultaneously. The high-temperature oxygen released from the first heat storage reactor 1 is extracted by a pump and introduced into the second heat storage reactor 4. The second heat storage reactor 4 is provided with a second composite energy storage medium 5 composed of an oxygen carrier and a phase change material. The second composite energy storage medium 5 absorbs the heat of the high-temperature oxygen and performs second-stage heat storage in a comprehensive form of thermochemistry, latent heat, and sensible heat. Heat; the oxygen carrier part in the oxygen-rich state undergoes a thermochemical reduction reaction to absorb heat and release oxygen, and the phase change material part undergoes a melting phase change to store heat in the form of latent heat. The temperature of the two parts of the material rises and sensible heat is stored at the same time; the oxygen released in the secondary heat storage reactor 4 is extracted by a pump, compressed by the compressor 26, and the surplus heat in the compressed oxygen is stored in the heat exchange storage tank 10 by the first heat exchanger 6 for the third stage of heat storage, and the compressed oxygen is stored in the oxygen storage tank 7; when the oxygen in the oxygen storage tank 7 is used as the oxygen source for the oxygen-enriched combustion unit in the cycle power generation system, the second heat exchanger 9 is used to exchange the oxygen in the heat exchange storage tank 10 The heat is preheated and then introduced into the circulating power generation subsystem through a pump; when the heat release system is working as a heat release heating system, the outside air is preheated by the third heat exchanger 11 and then pumped into the secondary heat storage reactor 4 through a pump. At this time, the oxygen carrier in the oxygen-deficient state in the second composite energy storage medium 5 undergoes a thermochemical oxidation reaction with the air, absorbing oxygen in the air while releasing chemical heat, and the phase change material partially undergoes a solidification phase change to release latent heat; Afterwards, the nitrogen-rich gas flowing out of the secondary heat storage reactor 4 is introduced into the primary heat storage reactor 1 through a pump, and the oxygen carrier in the oxygen-deficient state in the first composite energy storage medium 3 undergoes a thermochemical oxidation reaction with the nitrogen-rich gas. The oxidation reaction further absorbs oxygen while releasing chemical heat, and the phase change material undergoes a solidification phase change to release latent heat. The high-temperature nitrogen flowing out of the first-stage heat storage reactor 1 is pumped through the fourth heat exchanger 12 to release the high-temperature heat energy to the working fluid of the circulating power generation system. The nitrogen after heat exchange is compressed by the compressor, and the excess heat in the compressed nitrogen is stored in the heat exchange and storage tank 10 through the first heat exchanger 6. It is then stored in the nitrogen storage tank 8 for use in other nitrogen-using industries such as synthetic ammonia. The oxygen and circulating flue gas from the heat storage system are introduced into the combustion chamber 16 of the oxygen-enriched combustion unit to participate in combustion. The combustion chamber 16 serves as a heat source to provide heat for the supercritical CO2 cycle.After the flue gas produced by combustion passes through the denitrification device 17 and the dust collector 18, a part of it is pumped into the combustion chamber 16 to form circulating flue gas for combustion, and the remaining flue gas passes through the desulfurization device 19 and the compression purification device 20 and is captured by the CO2 capture device 21; the supercritical CO2 cycle power generation system uses the heated CO2 working medium turbine to do work, and the working medium is transported to the oxygen-enriched combustion unit combustion chamber 16 after passing through the heat exchanger 23, the condenser 25, and the compressor 26 and then flows through the heat exchanger to be heated and then participate in the cycle; the cycle power generation subsystem performs peak-shaving operation according to the load characteristics and peak-valley differences of the power system, which specifically includes two operating modes, namely The oxygen-rich combustion unit operates independently; the heat release unit operates in conjunction with the oxygen-rich combustion unit. During off-peak electricity demand, the oxygen-rich combustion unit operates independently, with combustion chamber 16 utilizing pure oxygen from oxygen storage tank 7 and recycled flue gas for oxygen-rich combustion. The s-CO2 circulating fluid flows through the combustion chamber 16 via a three-way valve for heat exchange, and after heat exchange, it flows into the turbine unit for turbine power generation. Excess off-peak electricity and wind / photovoltaic power heat and store the heat storage unit. During peak electricity demand, the heat release unit operates in conjunction with the oxygen-rich combustion unit. The s-CO2 circulating fluid, after being diverted via a three-way valve, exchanges heat for heat in the heat storage unit and combustion chamber 16, and after heat exchange, it flows into the turbine unit for turbine power generation.

[0056] The first composite energy storage medium 3 oxygen carrier is SrFeO 3-δ (oxidation-reduction temperature is 600℃-950℃), the metal phase change material is Cu56-Si27-Mg17 alloy (melting point is 770℃); the oxygen carrier in the second composite energy storage medium 5 is Ca2AlMnO 5+δ (oxidation-reduction temperature is 540℃-700℃), and the metal phase change material is pure aluminum (melting point is 660℃) as an example. The specific work flow is as follows:

[0057] When there is excess electricity and sufficient wind and photovoltaic power, energy storage mode is used. Wind power, photovoltaic power, and valley power are used to electrically heat the first-stage thermal storage reactor 1 to 1000°C. During the heating process, the first composite energy storage medium 3 stores heat in a combination of thermochemical, latent, and sensible forms. The oxygen-rich SrFeO3 undergoes a thermochemical reduction reaction, absorbing heat and releasing oxygen. The phase change material Cu56-Si27-Mg17 alloy melts and undergoes a solid-liquid phase transition, storing heat in the form of latent heat. The temperature of both materials rises, simultaneously storing sensible heat. The oxygen generated by the reaction is pumped out of the first-stage thermal storage reactor 1 and introduced into the second-stage thermal storage reactor 4. The oxygen temperature at the outlet of the first-stage thermal storage reactor 1b2 is 700-800°C, while the inlet of the second-stage thermal storage reactor 4B1 is 650-750°C. The second composite energy storage medium 5 in the second-stage thermal storage reactor 4 absorbs the heat from the high-temperature oxygen in a combination of thermochemical, latent, and sensible forms for second-stage heat storage. The oxygen-rich Ca2AlMnO 5+δA thermochemical reduction reaction absorbs heat and releases oxygen. The phase-change material, Al metal, undergoes a melting phase change, storing heat as latent heat. The temperatures of both materials rise, simultaneously storing sensible heat. A pump extracts oxygen from the secondary thermal storage reactor 4, where the B2 outlet gas temperature is 550-650°C. This oxygen is compressed by a compressor, and the first heat exchanger 6 stores the excess heat in the compressed oxygen in the thermal storage tank 10, which operates at 500°C. The compressed oxygen is then stored in the oxygen storage tank 7.

[0058] When power is scarce or the power load is too large, the energy release working mode is adopted. The outside air is preheated to 200-300℃ through the third heat exchanger 11 and pumped to the inlet of the secondary heat storage reactor 4A1. At this time, the second composite energy storage medium 5 is in the Ca2AlMnO 5+δ It undergoes a thermochemical oxidation reaction with the air, absorbing oxygen in the air while releasing chemical heat. The phase change material Al alloy undergoes a solidification phase change and releases latent heat. The gas at the outlet of the secondary heat storage reactor 4A2 is 500-600°C. The nitrogen-rich gas flowing out of the secondary heat storage reactor 4 is introduced into the inlet of the primary heat storage reactor 1a1 through a pump. The gas temperature at the inlet of a1 is 450-550°C. The SrFeO in the first composite energy storage medium 3 is in an oxygen-deficient state. 3-δ A thermochemical oxidation reaction with the nitrogen-rich gas further absorbs oxygen while releasing chemical heat. Simultaneously, the phase change material, Cu56-Si27-Mg17 alloy, undergoes a solidification phase transition, releasing latent heat. The nitrogen at the outlet of the primary heat storage reactor 1a2 is at a temperature of 700-750°C. This high-temperature gas is pumped through the fourth heat exchanger 12, releasing its high-temperature thermal energy to the working fluid of the circulating power generation system. After heat exchange, the nitrogen is compressed by a compressor. The excess heat in the compressed nitrogen is stored in the first heat exchanger 6 in the heat exchange and storage tank 10. Afterwards, it is stored in the nitrogen storage tank 8 for use in other nitrogen-using industries, such as ammonia synthesis.

[0059] The oxy-fuel combustion unit operates normally in both energy storage and release modes. Oxygen from the oxygen storage tank 7 passes through the second heat exchanger 9, exchanging heat from the heat storage tank 10. The oxygen is then pumped to the combustion chamber 16 to participate in combustion with the circulating flue gas. After passing through the second heat exchanger 9, the oxygen temperature is 300-400°C, and the circulating flue gas temperature is 200-300°C. The combustion chamber 16 serves as a heat source for the power generation system, providing heat for the supercritical CO2 cycle. The flue gas generated by combustion passes through the denitrification unit 17 and dust collector 18. A portion is pumped to form the circulating flue gas and introduced into the combustion chamber 16 for combustion. The remaining flue gas passes through the desulfurization unit 19 and the compression and purification unit 20 before being captured by the CO2 capture unit 21. The heated CO2 working fluid in the supercritical CO2 cycle power generation system is then used by the turbine to generate work. The resulting working fluid then passes through the regenerator 23, condenser 25, and compressor 26 before being delivered to the combustion chamber 16 of the oxy-fuel combustion unit and, after being heated by the heat exchanger, participates in the cycle.

[0060] The preferred embodiments of the present invention are described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, various equivalent transformations can be made to the technical solutions of the present invention, and these equivalent transformations all fall within the scope of protection of the present invention.

Claims

1. A high-temperature energy storage and air separation system for s-CO2 cycle power generation under oxygen-enriched combustion, characterized by: Including heat storage and release and air separation subsystem and cycle power generation subsystem; The heat storage and release and air separation subsystem includes a primary heat storage reactor, a secondary heat storage reactor, a first heat exchanger, an oxygen storage tank, a nitrogen storage tank, a second heat exchanger, a heat exchange and heat storage tank, a third heat exchanger and a fourth heat exchanger; An electric heating device and a first composite energy storage medium are arranged in the first-stage heat storage reactor; The secondary heat storage reactor is connected to the primary heat storage reactor via a pump, and a second composite energy storage medium is arranged in the secondary heat storage reactor; The first heat exchanger is connected to the secondary heat storage reactor via a pump and a compressor; The nitrogen storage tank is connected to the first heat exchanger; The oxygen storage tank is connected to the first heat exchanger; The second heat exchanger is connected to the oxygen storage tank; The heat exchange and heat storage tank is connected to the first heat exchanger and the second heat exchanger; The third heat exchanger is connected to the heat exchange and heat storage tank, and is connected to the secondary heat storage reactor through a pump; The fourth heat exchanger is connected to the first-stage heat storage reactor via a pump and is connected to the first heat exchanger via a compressor; The cycle power generation subsystem includes an oxygen-enriched combustion unit and a supercritical CO2 Brayton cycle power generation unit; The oxygen-enriched combustion unit includes an oxygen storage tank, a combustion chamber, a denitrification device, a dust collector, a desulfurization device, a compression purification device, and a CO2 capture device; The oxygen storage tank is connected to the combustion chamber via the second heat exchanger and pump, and the combustion chamber, denitrification device, dust collector, desulfurization device, compression purification device and CO2 capture device are connected in sequence; The supercritical CO2 Brayton cycle power generation unit includes a fourth heat exchanger, a turbine unit, a regenerator, a generator, a condenser, a compressor and a combustion chamber; The fourth heat exchanger is connected to the turbine unit; The turbine unit is connected to the regenerator; the turbine unit is connected to the generator; The regenerator is connected to the condenser, the condenser is connected to the compressor, and the compressor is connected to the regenerator; The regenerator is connected to the fourth heat exchanger and the combustion chamber through a three-way valve; The combustion chamber is connected to the turbine unit.

2. The high-temperature energy storage and air separation system for s-CO2 cycle power generation under oxygen-enriched combustion according to claim 1 is characterized by: Both the first-stage heat storage reactor and the second-stage heat storage reactor are axially insulated fixed-bed reactors, including a heat storage reactor shell, an insulation layer, upper and lower inlets and outlets, and corresponding two-way valves; the heat storage reactor shell is made of a high-temperature resistant alloy material, and the shell has good sealing performance; the heat storage reactor is equipped with upper and lower cut-off partitions, and electric heating equipment and several support plates are placed between the upper and lower cut-off partitions, and holes are left on the support plates for gas circulation; the insulation layer is a high-temperature refractory insulation material, which is wrapped and filled inside the first-stage heat storage reactor and the second-stage heat storage reactor body.

3. The high-temperature energy storage and air separation system for s-CO2 cycle power generation under oxygen-enriched combustion according to claim 1 is characterized in that: The oxygen storage tank and the nitrogen storage tank share the first heat exchanger and the heat exchange and heat storage tank, and the gas flow direction is controlled by a two-way valve.

4. The high-temperature energy storage and air separation system for s-CO2 cycle power generation under oxygen-enriched combustion according to claim 1 is characterized in that: The heat storage medium in the heat exchange storage tank is one or more of molten salt sensible heat or phase change heat storage material, high temperature heat transfer oil sensible heat storage material or metal phase change material, and its operating temperature is 200-500℃.

5. The high-temperature energy storage and air separation system for s-CO2 cycle power generation under oxygen-enriched combustion according to claim 1 is characterized in that: The first composite energy storage medium and the second composite energy storage medium are spherical composite capsules formed by oxygen carrier-coated phase change material, wherein the shell of the capsule is oxygen carrier material and the core of the capsule is metal phase change material.

6. The high-temperature energy storage and air separation system for s-CO2 cycle power generation under oxygen-enriched combustion according to claim 5 is characterized by: The diameter of the composite capsule is 3mm-50mm, the thickness of the shell is 0.5mm-10mm, and the diameter of the core is 2mm-40mm.

7. The high-temperature energy storage and air separation system for s-CO2 cycle power generation under oxygen-enriched combustion according to claim 5 is characterized by: The heat storage temperature range of the first composite energy storage medium is 600℃-1000℃; the oxygen carrier material of the shell of the first composite energy storage medium is BaCoO with an oxygen storage / release temperature of 600℃-1000℃ 3-δ 、LaMnO 3-δ 、SrCoO 3-δ 、SrFeO 3-δ , Co3O4, NiFe2O4, MnFe2O4, CaFe x Mn 1-x O 3-δ One or more of the metal oxide-based oxygen carriers; the core metal phase change material of the first composite energy storage medium is one or more of the aluminum-based and copper-based alloys with a phase change temperature of 600°C-1000°C; The optimal combination of the oxygen carrier and the metal phase change material is that the difference between the oxygen storage / release temperature of the oxygen carrier and the melting point of the metal phase change material is less than 200°C.

8. The high-temperature energy storage and air separation system for s-CO2 cycle power generation under oxygen-enriched combustion according to claim 5 is characterized by: The heat storage temperature range of the second composite energy storage medium is 400℃-700℃; the oxygen carrier material of the shell of the second composite energy storage medium is Ca2AlMnO with an oxygen storage / release temperature between 400℃-700℃ 5+δ and its derivative materials Ca 1.2 Sr 0.8 AlMnO 5+δ 、Ca(Al 1-x Ga x )MnO 5+δ 、Ca2Al(Mn 1-x Co x )O 5+δ One or more oxygen carrier materials; the core metal phase change material of the second composite energy storage medium is one or more aluminum-based alloys having a phase change temperature between 400°C and 700°C; The optimized combination of the oxygen carrier and the metal phase change material is that the difference between the oxygen storage / release temperature of the oxygen carrier and the melting point of the metal phase change material is less than 150°C.

9. A method for operating a high-temperature energy storage and air separation system for s-CO2 cycle power generation under oxygen-enriched combustion, characterized by: When the heat storage system is used for energy storage, the surplus electric energy such as off-peak electricity of the power grid or wind power, photovoltaic power, etc. is heated by electric heating equipment in the first-stage heat storage reactor by a first composite energy storage medium composed of an oxygen carrier and a phase change material for first-stage heat storage; during the heating process, the first composite energy storage medium stores heat in a comprehensive form of thermochemical, latent heat, and sensible heat, wherein the oxygen carrier in an oxygen-rich state undergoes a thermochemical reduction reaction to absorb heat and release oxygen, and the phase change material melts to undergo a solid-liquid phase change to store heat in the form of latent heat, and the temperature of the two parts of the material rises while sensible heat storage is performed; the high-temperature oxygen released from the first-stage heat storage reactor is extracted by a pump and introduced into the second-stage heat storage reactor; the second-stage heat storage reactor is provided with a second composite energy storage medium composed of an oxygen carrier and a phase change material, which absorbs heat and releases oxygen. The heat of high-temperature oxygen is collected to perform second-stage heat storage in a comprehensive form of thermochemical, latent, and sensible heat. The oxygen carrier portion in the oxygen-rich state undergoes a thermochemical reduction reaction to absorb heat and release oxygen, while the phase change material portion undergoes a melting phase change to store heat in the form of latent heat. The temperatures of the two materials rise while sensible heat storage is performed simultaneously. The oxygen released from the secondary heat storage reactor is extracted by a pump and compressed by a compressor. The excess heat in the compressed oxygen is stored in a heat exchange storage tank using a first heat exchanger for third-stage heat storage, and the compressed oxygen is stored in the oxygen storage tank. When the oxygen in the oxygen storage tank is used as the oxygen source for the oxygen-enriched combustion unit in the circulating power generation system, the heat in the heat exchange storage tank is exchanged for preheating using a second heat exchanger, and then introduced into the circulating power generation subsystem via a pump. When the heat supply system is working, the outside air is preheated by the third heat exchanger and then pumped into the secondary heat storage reactor. At this time, the oxygen carrier in the second composite energy storage medium, which is in an oxygen-deficient state, undergoes a thermochemical oxidation reaction with the air, absorbing oxygen from the air while releasing chemical heat. The phase change material undergoes a solidification phase change to release latent heat. Afterwards, the nitrogen-rich gas flowing out of the secondary heat storage reactor is introduced into the primary heat storage reactor through a pump, and the oxygen carrier in the oxygen-deficient state in the first composite energy storage medium undergoes a thermochemical oxidation reaction with the nitrogen-rich gas to further absorb oxygen and release chemical heat while simultaneously, the phase change material undergoes a solidification phase change to release latent heat; the high-temperature nitrogen flowing out of the primary heat storage reactor is pumped through the fourth heat exchanger to release the high-temperature heat energy to the working fluid of the circulating power generation system; the nitrogen after heat exchange is compressed by the compressor, and the excess heat in the compressed nitrogen is stored in the heat exchange and storage tank through the first heat exchanger, and then stored in the nitrogen storage tank for use in other nitrogen-using industries such as synthetic ammonia; the oxygen and circulating flue gas from the heat storage system are introduced into the combustion chamber of the oxygen-enriched combustion unit to participate in combustion, and the combustion chamber serves as a heat source to provide heat for the supercritical CO2 cycle; after the flue gas generated by combustion passes through the denitrification device and the dust collector, a part of it is pumped to form circulating flue gas and introduced into the combustion chamber to participate in combustion, and the remaining flue gas passes through the desulfurization device and the compression and purification device and is captured by the CO2 capture device; The supercritical CO2 cycle power generation system uses the heated CO2 working medium to generate power through the turbine. After the working medium passes through the regenerator, condenser, and compressor, it is transported to the combustion chamber of the oxygen-enriched combustion unit and flows through the heat exchanger to be heated before participating in the cycle. The cyclic power generation subsystem operates in peak-shaving mode according to the load characteristics and peak-valley differences of the power system. Specifically, it includes two operating modes: the oxygen-rich combustion unit operates alone; the heat release unit operates in conjunction with the oxygen-rich combustion unit. When the electricity consumption is at the valley value, the oxygen-rich combustion unit operates alone, and the combustion chamber uses pure oxygen from the oxygen storage tank and recycled flue gas to perform oxygen-rich combustion. The s-CO2 circulating working fluid flows through the combustion chamber through a three-way valve for heat exchange. After heat exchange, the working fluid flows into the turbine unit for turbine power generation. The excess valley electricity and wind / photovoltaic power are used to heat and store the heat storage unit. During peak electricity consumption, the heat release unit is operated in conjunction with the oxygen-rich combustion unit. The s-CO2 circulating working fluid is diverted by the three-way valve and exchanges heat in the heat storage unit and the combustion chamber. The working fluid after heat exchange flows into the turbine unit for turbine power generation.

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