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

Abstract

The invention discloses a high-temperature energy storage and air separation system and method for s-CO2 cycle power generation under oxygen-enriched combustion. The high-temperature energy storage and air separation system comprises 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 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 denitration device, a dust remover, a desulfurization device, a compression purification device and a CO2 trapping device; the supercritical CO2 Brayton cycle power generation unit comprises a turbine unit, a heat regenerator, a power generator, a condenser and a compressor; according to the invention, a novel heat and energy storage and air separation technology is matched with a supercritical CO2 cycle power generation system under oxygen-enriched combustion, and a power generation system design scheme capable of realizing oxygen self-supply, CO2 separation and high system efficiency is formed.

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 the fields of solar / wind power generation grid connection and power grid peak shaving and valley filling. Background Art

[0002] Coal-fired power generation has serious problems such as low power supply and demand matching, difficulty in absorbing off-peak electricity, and high CO2 emissions. Furthermore, renewable energy generation is intermittent and unstable, making it impossible to connect to the grid directly. To solve these problems, it is urgent to develop new low-carbon power generation technologies and new energy storage technologies.

[0003] Oxygen-enriched combustion technology increases the CO2 concentration in 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-work conversion, with the advantages of small size, high efficiency and low pollution. The oxygen-enriched combustion combined with 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 way to solve problems such as peak-valley difference in power grids and grid connection of renewable energy. Among the many energy storage technologies being developed, phase change thermal energy storage and thermochemical thermal energy storage are gradually being used in energy storage power generation systems because of their advantages such as high heat storage density and low heat loss. In the existing high-temperature thermal energy storage power generation system, the more mature technology is to use nitrate as the sensible heat molten salt heat storage medium. However, the nitrate material limits the maximum temperature to no more than 560°C, which reduces the overall power generation efficiency and cannot be coupled with the supercritical CO2 generator set. On the one hand, the use of metals and their alloys as phase change thermal storage materials for thermal energy storage has a higher operating temperature and thermal storage density, but metals are prone to leakage during the phase change process, and there are problems such as strong corrosion and material deactivation under high temperature conditions, and packaging technology is required to process them. However, the thermal storage density of the composite phase change material encapsulated with inert materials is lower than that of the pure phase change material, which limits its scope of application. On the other hand, the chemical chain thermochemical thermal storage (CL-TES) technology in thermochemical energy storage is a method of using oxygen carrier materials to store and release thermal energy 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 is the main problem that limits its application, mainly due to the slow reaction and diffusion rate of gas in solid materials. When the oxygen carrier material is formed into large particles and applied to a fixed bed reactor, a considerable portion of the oxygen carrier material inside the particles cannot quickly participate in the redox reaction, resulting in an incomplete reaction and a reduction in 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-rich 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 provide a system and method for high-temperature energy storage and air separation for s-CO2 cycle power generation under oxygen-enriched combustion in view of the deficiencies of the above-mentioned prior art. The 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 metal phase change materials with high thermal storage density to develop a composite energy storage medium with high thermal storage density, which not only ensures that the oxygen-carrier thermochemical material has a shorter gas diffusion path and a rapid reaction effect, but also solves the problem of metal phase change material packaging, realizes the complementary advantages of thermochemical thermal energy storage and phase change thermal energy storage, and can also realize 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 to form a power generation system design that can realize 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 utilization of energy 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 heat exchange storage tank through a pump It is connected to the first-stage 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, 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 properties; the heat storage reactor is equipped with upper and lower cut-off baffles, and an electric heating device and a plurality of support plates are arranged between the upper and lower cut-off baffles, 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 carriers coating 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.

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

[0016] Preferably, the heat storage temperature range of the first composite energy storage medium is 600°C-1000°C; the shell oxygen carrier material 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 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 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 ) 5+δ One or more of the oxygen carrier materials; the core metal phase change material of the second composite energy storage medium is one or more of the 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 high-temperature energy storage and air separation operation method for s-CO2 cycle power generation under oxygen-rich combustion. When the heat storage system performs energy storage work, the surplus electric energy such as valley electricity of the power grid or wind power, photovoltaic power, etc. is heated by an electric heating device to perform the first-stage heat storage by a first composite energy storage medium composed of an oxygen carrier and a phase change material in a first-stage heat storage reactor. During the heating process, the first composite energy storage medium stores heat in a comprehensive form of thermochemistry, 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, 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 by 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 to perform 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 a heat exchanger and heat storage tank by a 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 storage tank, the second heat exchanger is used to exchange the heat in the heat exchange storage tank for preheating, and then the heat is introduced into the circulating power generation subsystem through a pump; when the heat release heating 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, absorbs oxygen in the air and releases chemical heat at the same time, 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 and release chemical heat at the same time, and the phase change material The material undergoes a solidification phase change to release 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 surplus heat in the compressed nitrogen is stored in the heat exchange and heat 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 the 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 rest of the 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 fluid turbine to do work. After the working fluid 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 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 operation modes: the oxygen-enriched combustion unit operates alone; the heat release unit matches the oxygen-enriched combustion unit to operate; when the power consumption is valley value, the oxygen-enriched combustion unit operates alone, and the combustion chamber uses pure oxygen from the oxygen storage tank and the circulating flue gas for oxygen-enriched combustion, and the s-CO2 circulating working fluid flows through the combustion chamber through a three-way valve for heat exchange. After the heat exchange, the working fluid flows into the turbine unit for turbine power generation, and the excess valley electricity and wind / photovoltaic power heat and store the heat storage unit; when the power consumption is peak, the heat release unit matches the oxygen-enriched combustion unit to operate, and the s-CO2 circulating working fluid is diverted through the three-way valve to exchange heat in the heat storage unit and the combustion chamber, and the working fluid after heat exchange flows into the turbine unit for turbine power generation. ;

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

[0020] 1. Considering the advantages and disadvantages of thermochemical energy storage and phase change energy storage, an improved composite energy storage material is proposed. On the basis of the original encapsulated phase change capsule, the oxygen carrier-thermochemical reaction layer is used to replace the phase change capsule sensible heat shell layer, which ensures that the thermochemical material has a shorter gas diffusion path, increases the heat storage capacity of the phase change heat storage capsule, and realizes the complementary advantages of thermochemical energy storage 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. The oxygen-enriched combustion combined with supercritical CO2 cycle power generation system is adopted. The oxygen-enriched combustion unit uses pure oxygen generated from the oxygen carrier and the circulating flue gas for oxygen-enriched combustion, realizing the separation and capture of CO2. Since the oxygen is preheated by the heat exchanger and heat storage tank, the inlet temperature of the combustion chamber is increased, further enhancing the 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 capsule, phase change capsule, and pure oxygen carrier sphere in different preparation stages of the embodiments of the present invention;

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

[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 heat storage comparison diagram of ceramic balls, thermochemical balls, Al@Al2O3, and Al@CAMO of the same size in the embodiment of the present invention;

[0033] Fig. 9 This is a heat storage comparison diagram 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] The components include: 1. a primary heat storage reactor; 2. an electric heating device; 3. a first composite energy storage medium; 4. a secondary heat storage reactor; 5. a second composite energy storage medium; 6. a first heat exchanger; 7. an oxygen storage tank; 8. a nitrogen storage tank; 9. a second heat exchanger; 10. a heat exchange and heat storage tank; 11. a third heat exchanger; 12. a fourth heat exchanger; 13. a first valve; 14. a second valve; 15. a third valve; 16. a combustion chamber; 17. a denitrification device; 18. a dust collector; 19. a desulfurization device; 20. a compression and purification device; 21. a CO2 capture device; 22. a turbine unit; 23. a regenerator; 24. a generator; 25. a condenser; 26. a compressor; 27. a fourth valve; 28. a fifth valve; 29. ​​a sixth valve. DETAILED DESCRIPTION

[0035] The present invention will be further described in detail below in conjunction with 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-rich combustion is provided, including 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. The heat storage and release and air separation subsystem realizes the functions of cascade heat storage and air separation by utilizing the two-stage reactor and the composite energy storage medium placed therein, generates high-purity oxygen and nitrogen, and improves the energy utilization rate and economic benefits of the system.

[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 power 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 through 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 through a pump, so as to transport 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 through a pump, so as to transport the nitrogen-rich gas generated after flowing through the secondary heat storage reactor 4. A second composite energy storage medium 5 is arranged in the secondary heat storage reactor 4.

[0040] Preferably, the primary heat storage reactor 1 and the secondary heat storage reactor 4 are both 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 built with upper and lower cut-off baffles, and an electric heating device 2 and a plurality of support plates are placed between the upper and lower cut-off baffles. The support plates are provided with holes for gas circulation, and the hole size is 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 freely stacked or orderly stacked on the support plate. The insulation layer is a high-temperature refractory insulation material, which is wrapped and filled inside the primary heat storage reactor 1 and the secondary heat storage reactor 4 body to reduce the heat loss of the heat storage reactor.

[0041] Preferably, the first composite energy storage medium 3 and the second composite energy storage medium 5 are spherical composite capsules formed by oxygen carriers encapsulating 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 encapsulation capsules, the composite capsule has a simple structure, only has an oxygen carrier encapsulation shell layer, and the composite capsule has excellent heat storage capacity and also has an air separation function. The schematic diagram of the composite capsule structure is shown in FIG. Figure 2As shown. The oxygen carrier is coupled with the high-temperature phase change capsule to produce a composite energy storage capsule with the oxygen carrier as the outermost layer and the phase change material as the core. The outermost layer of the capsule particles is the oxygen carrier, which ensures that it has a short gas diffusion path and ensures that the oxygen carrier air separation reaction and the thermochemical heat storage process proceed smoothly; while the core part uses a high thermal conductivity metal material for phase change heat storage, which can provide a high heat storage density and is not affected by the diffusion path.

[0042] The first composite energy storage medium uses SrFeO as the oxygen carrier 3-δ , a composite capsule of Cu56-Si27-Mg17 alloy with a core of 3.5 mm is taken as an example, 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 Ca2AlMnO 5+δ Take the composite capsule with Al core of 5mm as an example, the paraffin layer is 0.25, and 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, the paraffin is heated and melted, and the 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 make 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 the organic binder. In this process, the paraffin will be decomposed into gas, thereby forming a cavity layer between the outer shell and the internal 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, and finally the required composite capsule sample is obtained. 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 rupture of the capsule shell.

[0044] Phase change capsules were prepared using the same method. The samples in each process were as follows. Figure 4 As shown. The same method is used to form a mixture of oxygen carrier powder and binder gel into spheres of the same size. A heat storage test is performed, 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, 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 Fig. 9 As shown, it can be found that the heat storage density of the composite capsules is the highest.

[0048] Preferably, the diameter of the composite capsule is 3mm-50mm, the shell thickness is 0.5mm-10mm, and the core diameter is 2mm-40mm. To ensure that the composite energy storage medium remains stable and does not break during the 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 the cyclic use.

[0049] Preferably, the heat storage temperature range of the first composite energy storage medium 3 is 600°C-1000°C; the shell oxygen carrier material 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 optimal combination 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. For example, the oxygen carrier is BaCoO 3-δ (oxidation-reduction 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 shell oxygen carrier material 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 ) 5+δ One or more of the oxygen carrier materials; the core metal phase change material of the second composite energy storage medium 5 is one or more of the aluminum-based alloys with a phase change temperature between 400°C and 700°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 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 the 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 heat storage tank 10, and is connected to the A1 inlet of the secondary heat storage reactor 4 through a pump. The third heat exchanger 11 is connected to the outside air, and is used to introduce the 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 through a pump, and is used to exchange the heat of the high-temperature nitrogen after passing through the primary heat storage reactor 1 to the circulating power generation subsystem; the fourth heat exchanger 12 is connected to the first heat exchanger 6 through a compressor, and the fourth heat exchanger 12 is connected to the a2 outlet of the primary heat storage reactor 1 through 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 heat storage tank 10 through a compressor, and is used to store 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, the second valve 14 is opened, and the oxygen and the residual 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, the first valve 13 is opened, and the nitrogen and the residual 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 preheated by the heat exchanger 11 in exchange for the heat of the heat exchange storage tank 10 is extracted by a pump. 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 materials, high-temperature heat transfer oil sensible heat storage materials or metal phase change materials, 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 air separation subsystem and the waste heat flue gas after dust removal; 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 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 ... 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 medium after heat exchange in the fourth heat exchanger 12 or the working medium heated by the combustion chamber 16 to do work; the turbine unit 22 is connected to the regenerator 23, and the regenerator 23 uses the waste heat of the working medium after doing work to heat the working medium after condensation and compression; the turbine unit 22 is connected to the generator 24, and the generator 24 is used for generating electricity; the regenerator 23 is connected to the condenser 25, and the condenser 25 is used to condense the working medium 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 heat storage unit through the second heat exchanger 9, and then transported to the combustion chamber 16 by a 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 heat storage system performs energy storage, the surplus electric energy such as valley electricity of the power grid or wind power, photovoltaic power, etc. is heated by 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 the first stage of 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, 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. The temperature of the two parts of the material rises and sensible heat is stored at the same time; the high-temperature oxygen released by 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, which absorbs the heat of the high-temperature oxygen and performs the second stage of 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 a 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 third-stage 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 of 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 heating system is used to release energy, 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; thereafter, 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 and releases chemical heat at the same time, and the phase change material undergoes solidification phase change to release latent heat; the high-temperature nitrogen flowing out of the first-level heat storage reactor 1 flows through the fourth heat exchanger 12 through the pump 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 surplus heat in the compressed nitrogen is stored in the heat exchange and heat storage tank 10 through the first heat exchanger 6, and 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, and 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 rest of the 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 regenerator 23, the condenser 25, and the compressor 26 and flows through the heat exchanger to be heated and then participate in the circulation; 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, respectively. The oxygen-enriched combustion unit operates alone; the heat release unit operates in conjunction with the oxygen-enriched combustion unit; when the electricity consumption is at a valley value, the oxygen-enriched combustion unit operates alone, the combustion chamber 16 uses the pure oxygen in the oxygen storage tank 7 and the circulating flue gas for oxygen-enriched combustion, the s-CO2 circulating working fluid flows through the combustion chamber 16 through a three-way valve for heat exchange, and the working fluid after heat exchange flows into the turbine unit for turbine power generation, and the excess valley electricity and wind / photovoltaic power heat and store the heat storage unit; when the electricity consumption is at a peak value, 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, and exchanges heat in the heat storage unit and the combustion chamber 16, and the working fluid after heat exchange 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 workflow is as follows:

[0057] When there is a surplus of electricity and sufficient wind and photovoltaic power, the energy storage mode is adopted, and wind power / photovoltaic power / valley power is electrically heated to the first-level heat storage reactor 1 to 1000℃. During the heating process, the first composite energy storage medium 3 stores heat in the form of thermochemistry, latent heat, and sensible heat. Among them, SrFeO3 in an oxygen-rich state undergoes a thermochemical reduction reaction to absorb heat and release oxygen, and the phase change material Cu56-Si27-Mg17 alloy 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 and sensible heat is stored at the same time. The oxygen generated by the reaction is pumped out of the first-level heat storage reactor 1 and introduced into the second-level heat storage reactor 4. The oxygen temperature at the outlet of the first-level heat storage reactor 1b2 is 700-800℃, and the inlet of the second-level heat storage reactor 4B1 is 650-750℃. The second composite energy storage medium 5 in the second-level heat storage reactor 4 absorbs the heat of the high-temperature oxygen and performs the second-level heat storage in the form of thermochemistry, latent heat, and sensible heat. Among them, Ca2AlMnO in an oxygen-rich state 5+δThermochemical reduction reaction occurs to absorb heat and release oxygen, and the phase change material Al metal undergoes 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 in the secondary heat storage reactor 4 is extracted by a pump. The B2 outlet gas temperature of the secondary heat storage reactor 4 is 550-650°C. It is compressed by a compressor, and the first heat exchanger 6 is used to store the excess heat in the compressed oxygen in the heat exchange storage tank 10. The operating temperature of the heat exchange storage tank 10 is 500°C. The compressed oxygen is 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°C by 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 and releasing chemical heat at the same time. 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 Thermochemical oxidation reaction with nitrogen-rich gas further absorbs oxygen and releases chemical heat. At the same time, the phase change material Cu56-Si27-Mg17 alloy undergoes solidification phase change to release latent heat. The nitrogen temperature at the outlet of the first-stage heat storage reactor 1a2 is 700-750°C. The high-temperature gas flows through the fourth heat exchanger 12 through a pump to release high-temperature heat energy to the working fluid of the circulating power generation system. The heat-exchanged nitrogen is compressed by a compressor, and the surplus heat in the compressed nitrogen is stored in the heat exchange and heat storage tank 10 through the first heat exchanger 6, and then stored in the nitrogen storage tank 8 for use in other nitrogen-using industries such as synthetic ammonia.

[0059] Whether in energy storage mode or energy release mode, the oxygen-enriched combustion unit operates normally. The oxygen in the oxygen storage tank 7 exchanges heat in the heat exchange storage tank 10 through the second heat exchanger 9, and is pumped to the combustion chamber 16 to participate in combustion with the circulating flue gas. The oxygen temperature after passing through the second heat exchanger 9 is 300-400°C, and the circulating flue gas temperature is 200-300°C. The combustion chamber 16 serves as one of the heat sources of the power generation system and provides heat for the supercritical CO2 cycle. After the flue gas generated by the combustion passes through the denitrification device 17 and the dust collector 18, a part of it is pumped to form circulating flue gas and introduced into the combustion chamber 16 to participate in 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 work, and the working medium after work passes through the regenerator 23, the condenser 25, and the compressor 26, and is transported to the combustion chamber 16 of the oxygen-enriched combustion unit and flows through the heat exchanger to be heated and participate 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 belong to the protection scope 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: It includes 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 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 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 primary heat storage reactor via a pump and connected to the first heat exchanger via a compressor; The cycle power generation subsystem includes an oxyfuel 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 the 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.

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 in that: Both the primary heat storage reactor and the secondary 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 properties; the heat storage reactor is equipped with upper and lower cut-off partitions, and electric heating equipment and a number of 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.

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 working 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 carriers covering 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.

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 in that: The diameter of the composite capsule is 3mm-50mm, the thickness of the shell layer 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 in that: The heat storage temperature range of the first composite energy storage medium is 600°C-1000°C; the shell oxygen carrier material 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 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 in that: 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 ) 5+δ One or more of the oxygen carrier materials; the core metal phase change material of the second composite energy storage medium is one or more of the aluminum-based alloys having a phase change temperature between 400°C and 700°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 150°C.

9. A method for operating high-temperature energy storage and air separation for s-CO2 cycle power generation under oxygen-enriched combustion, characterized in that: When the heat storage system performs energy storage work, the surplus electric energy such as valley electricity of the power grid or wind power, photovoltaic power, etc. is heated by an electric heating device to heat the first composite energy storage medium composed of oxygen carriers and phase change materials in the first heat storage reactor for the first stage heat storage; during the heating process, the first composite energy storage medium stores heat in a comprehensive form of thermochemistry, 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, 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 by the first heat storage reactor is extracted by a pump and introduced into the second heat storage reactor; the second heat storage reactor is provided with a second composite energy storage medium composed of oxygen carriers and phase change materials, which absorbs heat and releases oxygen. The heat of high-temperature oxygen is collected to perform the second-stage heat storage in the 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. 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 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. When the oxygen in the oxygen storage tank is used as the oxygen source of the oxygen-rich combustion unit in the circulating power generation system, the second heat exchanger is used to exchange the heat in the heat exchange storage tank for preheating, and then introduced into the circulating power generation subsystem by a pump. When the heat-releasing heating system is working, the outside air is preheated by the third heat exchanger and then pumped to the secondary heat storage reactor by a pump. At this time, the oxygen carrier in the second composite energy storage medium in an oxygen-deficient state undergoes a thermochemical oxidation reaction with the air, absorbing oxygen in the air while releasing chemical heat, and 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 at the same time, and 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 flows through the fourth heat exchanger through a pump 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 a compressor, and the surplus heat in the compressed nitrogen is stored in the heat exchange and heat storage tank through the first heat exchanger, and then stored in a 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 the combustion passes through the denitrification device and the dust collector, a part of it is formed into circulating flue gas through a pump 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 fluid turbine to do work. After doing work, the working fluid passes through the regenerator, condenser, and compressor, and 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 cycle power generation subsystem performs peak load regulation operation according to the load characteristics and peak-valley differences of the power system. Specifically, it includes two operation modes: the oxygen-rich combustion unit operates alone; the heat release unit operates in combination with the oxygen-rich combustion unit; when the power consumption is at the valley value, the oxygen-rich combustion unit operates alone, and the combustion chamber uses the pure oxygen in the oxygen storage tank and the circulating flue gas for oxygen-rich combustion. The s-CO2 circulating working fluid flows through the combustion chamber through the 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 heat and store the heat storage unit. When electricity consumption is at its peak, the heat release unit is matched with the oxygen-rich combustion unit for operation. 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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