Systems and methods for liquid CO2 energy storage coupled with oxygen-enriched combustion in coal-fired power units

Abstract

The application discloses a system and method for coupling liquid CO2 energy storage and oxygen-enriched combustion of a coal-fired unit, and belongs to the technical field of thermal power generation. The system comprises a multi-stage compressor, a heat exchanger, a liquid / gas CO2 storage tank, a cryogenic pump, a gasifier, a CO2 turbine, a deep-cooling air separation nitrogen production device, an oxygen tank, a mixer, a boiler and a dust removal device. Excess electric energy drives purified CO2 after multi-stage compression, and the compression waste heat preheats boiler feed water. The CO2 is liquefied through heat exchange and stored in a liquid tank to realize energy storage. When the energy is released, the liquid CO2 is pressurized by the cryogenic pump, gasified and heat-exchanged to drive the turbine to generate electricity, and the gaseous CO2 is stored in a gas tank after work. Nitrogen is produced as a by-product through deep-cooling air separation, and the oxygen is stored in the oxygen tank. The boiler adopts oxygen-enriched combustion, and high-concentration CO2 in flue gas after dust removal is introduced into a coal-electricity CO2 storage tank. The CO2 in the storage tank is mixed with oxygen in a proportioning manner, and is sent into the boiler in multiple paths after temperature rising of an air preheater to serve as air distribution at different levels, so that the CO2 is recycled and used, and the unit peak regulation and energy storage are integrated.

Description

Technical Field

[0001] This invention belongs to the field of thermal power generation technology, specifically relating to a system and method for coupling liquid CO2 energy storage with oxygen-enriched combustion in coal-fired power units. Background Technology

[0002] As the cornerstone of the power system, coal-fired power units are facing the dual pressures of deep decarbonization and flexible regulation. Against this backdrop, exploring the deep integration of carbon capture, utilization, and storage (CCUS) technologies with energy storage technologies has become an important direction for promoting the low-carbon transformation of coal-fired power plants. The combination of liquid carbon dioxide energy storage technology and oxy-fuel combustion technology in coal-fired power units provides an innovative technological path to achieve this goal.

[0003] Liquid carbon dioxide energy storage, as an emerging compressed gas energy storage technology, has significant technical advantages: the critical point of carbon dioxide is easy to reach, the power consumption of the liquefaction process is low, and the energy density is much higher than that of traditional compressed air energy storage; at the same time, carbon dioxide is widely available, inexpensive, non-toxic, and non-flammable as a working fluid, and it has no special dependence on geological conditions, allowing for flexible site selection. More importantly, this energy storage method can achieve combined cooling, heating, and electricity generation and supply, with high overall energy conversion efficiency and good grid peak-shaving response capability.

[0004] Meanwhile, oxy-fuel combustion technology is considered one of the most promising pathways for large-scale carbon capture in coal-fired power units. This technology uses high-purity oxygen instead of air in combustion, increasing the carbon dioxide concentration in flue gas to over 90%, achieving low-cost carbon capture without complex gas separation. However, traditional oxy-fuel combustion systems still have room for efficiency improvement in areas such as oxygen production energy consumption, flue gas recirculation, and heat matching.

[0005] Deeply coupling liquid carbon dioxide energy storage systems with oxy-fuel combustion in coal-fired power units can leverage the synergistic effects of both. The high-concentration carbon dioxide produced by oxy-fuel combustion can be directly used as the working fluid source for the liquid carbon dioxide energy storage system, eliminating the intermediate steps of external carbon dioxide capture and compression, and achieving efficient recycling of carbon resources. Summary of the Invention

[0006] This invention provides a system and method for coupling liquid CO2 energy storage with oxy-fuel combustion in coal-fired power units. The purpose is to improve the overall energy efficiency of industrial production by combining liquid CO2 energy storage with oxy-fuel combustion, since the efficiency of existing compressed air energy storage is lower than that of liquid CO2 energy storage. Furthermore, the flexible charging and discharging of the energy storage system can smooth out load fluctuations caused by peak shaving in the oxy-fuel combustion system, thereby achieving the integrated goal of low-carbon, high-efficiency, and flexible operation of coal-fired power units.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: The system for liquid CO2 energy storage coupled with oxygen-enriched combustion in a coal-fired unit includes a multi-stage compressor, heat exchanger, liquid CO2 storage tank, cryogenic pump, gasifier, CO2 turbine, gaseous CO2 storage tank, filter, cryogenic air separation nitrogen generator, O2 storage tank, gas mixer, air preheater, dust collector, coal-fired power plant CO2 storage tank and boiler body; The inlet of the multistage compressor is connected to the heat exchanger, the outlet of the heat exchanger is connected to the liquid CO2 storage tank, the liquid CO2 storage tank is connected to the vaporizer via a cryogenic pump, the vaporizer is interconnected with the heat exchanger, the high-pressure cryogenic CO2 gas outlet of the vaporizer is connected to the inlet of the CO2 turbine, the outlet of the CO2 turbine is connected to the gaseous CO2 storage tank, and the gaseous CO2 storage tank is connected to the multistage compressor via a filter. The O2 outlet of the cryogenic air separation nitrogen generator is connected to the O2 storage tank. The flue gas from the boiler body is connected to the coal-fired power plant CO2 storage tank after being dedusted by a dust collector. The outlets of the O2 storage tank and the coal-fired power plant CO2 storage tank are connected to the gas mixer. The outlet of the gas mixer is connected to the boiler body through an air preheater installed in the flue at the tail end of the boiler body.

[0008] A further improvement of the present invention is that redundant electricity is used to perform work on a multi-stage compressor.

[0009] A further improvement of this invention is that the multi-stage compressor increases the pressure of CO2 by utilizing the principle of multi-stage compression.

[0010] A further improvement of the present invention is that the heat released by the multi-stage compressor is used to heat the boiler feedwater.

[0011] A further improvement of this invention is that the cryogenic air separation nitrogen generator is used to cryogenically cool air and separate O2 and N2 by utilizing the difference in liquefaction pressure.

[0012] A further improvement of this invention is that the N2 produced by the cryogenic air separation nitrogen generator is used as an industrial product.

[0013] A further improvement of the present invention is that the electricity generated after the CO2 turbine does work is connected to the power grid.

[0014] A further improvement of the present invention is that the CO2 gas stored in the coal-fired power plant CO2 storage tank serves as a supplement to the gaseous CO2 storage tank.

[0015] A method for coupling liquid CO2 energy storage with oxy-fuel combustion in a coal-fired power unit, the method being based on the aforementioned system for coupling liquid CO2 energy storage with oxy-fuel combustion in a coal-fired power unit, comprising: Filtered CO2 gas is fed into a multi-stage compressor along with redundant electricity for multi-stage pressurization, releasing heat to heat boiler feedwater. The compressed CO2 then enters a heat exchanger to exchange heat with a refrigerant before being stored in a liquid CO2 storage tank. When energy needs to be released, the liquid CO2 is pumped from the storage tank to a cryogenic pump, and then to a vaporizer for further heat exchange with the refrigerant. The resulting high-pressure, low-temperature CO2 gas is fed into a CO2 turbine to generate electricity for the grid. The CO2 gas remaining after the turbine's operation is then returned to a gaseous CO2 storage tank. The process involves: The boiler body undergoes oxygen-enriched combustion; the resulting flue gas is then filtered by a dust collector to obtain CO2 gas with a concentration of over 90%, which is then stored in a coal-fired power plant CO2 storage tank; N2 produced using a cryogenic air separation nitrogen generator is used as an industrial product, while the generated O2 is stored in an O2 storage tank; the O2 in the O2 storage tank and the CO2 in the coal-fired power plant CO2 storage tank are then mixed and heated together in a gas mixer; the resulting mixed gas is used as primary air, secondary air, and burnout air, heated in an air preheater, and then sent to the boiler body for combustion.

[0016] Compared with the prior art, the present invention has at least the following beneficial technical effects: The system and method for coupling liquid CO2 energy storage with oxy-fuel combustion in coal-fired power units provided by this invention overcomes the shortcomings of existing technologies such as slow peak-shaving rate of traditional coal-fired power units, high cost of raw materials for oxy-fuel combustion, low resource utilization rate of CO2 capture products, shortage of liquid CO2 energy storage gas source, and waste of compression heat, thereby improving the economic efficiency and low-carbon performance of the unit in multiple dimensions.

[0017] First, by relying on liquid CO2 energy storage to smooth unit load fluctuations, surplus electricity drives multi-stage compression to complete CO2 liquefaction and energy storage, and CO2 gasification drives turbine grid-connected power generation during peak electricity demand, thereby enabling the unit to quickly increase and decrease load and smooth the output curve, greatly improving the flexible peak-shaving capability of coal-fired units and adapting to the peak-shaving needs of new energy grid connection.

[0018] Secondly, it enables closed-loop energy supply of high-purity CO2 produced by the power plant. After the boiler undergoes oxygen-enriched combustion and dust removal, high-concentration CO2 is enriched and stored in the coal-fired power plant CO2 storage tank. This CO2 can be used as raw material for the oxygen-enriched combustion cycle flue gas and can also supplement the gas source of the gaseous CO2 storage tank. This solves the problems of high cost and unstable gas source of liquid CO2 energy storage by purchasing gas externally. Relying on the self-produced CO2 to stabilize the energy storage gas source, the stability of the energy storage system and the energy storage capacity are improved.

[0019] Third, the waste heat released during the multi-stage CO2 compression process is used for boiler feedwater preheating, recovering waste heat, reducing boiler coal consumption, and effectively reducing unit power generation coal consumption and power generation costs.

[0020] Fourth, the system is equipped with a cryogenic air separation unit to co-produce nitrogen and oxygen. The nitrogen is sold as an industrial product to generate revenue, while the oxygen is mixed with CO2 produced by the power plant in a flexible ratio in the mixer. After the mixed gas is heated by the air preheater, it is sent into the furnace in stages to serve as primary air, secondary air and burnout air. The oxygen content can be increased as needed to improve the ignition and burnout effect of inferior fuels and improve the boiler combustion efficiency.

[0021] Fifth, the system achieves the co-production of multiple products including electricity, steam, O2, N2, and high-purity CO2, and utilizes the carbon capture byproducts of oxygen-enriched combustion as resources, simultaneously realizing deep carbon reduction and diversified benefits for the unit, combining environmental benefits with industrial promotion value.

[0022] In summary, the system and method for coupling liquid CO2 energy storage with oxy-fuel combustion in coal-fired power plants provided by this invention deeply couples liquid CO2 energy storage with oxy-fuel combustion in coal-fired power plants. It utilizes surplus electricity from the unit to liquefy CO2 for energy storage, and during the energy release phase, turbine power generation rapidly smooths out fluctuations in thermal power load, improving the unit's peak-shaving flexibility. High-purity CO2 enriched by oxy-fuel combustion in the boiler is stored in the coal-fired power plant's CO2 storage tank, which not only replenishes the gas source of the energy storage system and expands its capacity, but also serves as a circulating combustion medium in the furnace. Waste heat from CO2 compression is recovered to preheat boiler feedwater, effectively reducing the unit's coal consumption. Byproduct nitrogen from the air separation unit is sold externally, and oxygen is flexibly mixed with self-produced CO2. Adjusting the oxygen content of the mixed gas optimizes furnace combustion conditions and improves fuel burnout rate. The entire system achieves combined heat and power (CHP) production of electricity, steam, industrial nitrogen, and high-purity CO2, with on-site resource utilization of carbon capture products. This reduces carbon emissions from coal-fired power plants while broadening the power plant's profit channels, demonstrating high system integration and significant economic benefits. Attached Figure Description

[0023] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0024] Figure 1 This is a schematic diagram of the system of the present invention.

[0025] Explanation of reference numerals in the attached figures: 1-Multistage compressor, 2-Heat exchanger, 3-Liquid CO2 storage tank, 4-Cryogenic pump, 5-Vaporizer, 6-CO2 turbine, 7-Gaseous CO2 storage tank, 8-Filter, 9-Cryogenic air separation nitrogen production equipment, 10-O2 storage tank, 11-Gas mixer, 12-Air preheater, 13-Dust collector, 14-Coal-fired power plant CO2 storage tank, 15-Boiler body. Detailed Implementation

[0026] In the following description, only certain exemplary embodiments are briefly described. As those skilled in the art will recognize, the described embodiments can be modified in various ways without departing from the spirit or scope of the invention. Therefore, the drawings and description are considered to be exemplary in nature and not restrictive.

[0027] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0028] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0029] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a communication connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0030] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature being directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature being directly above or diagonally above the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0031] It should be understood that, when used in this specification and the appended claims, the terms "comprising" and "including" indicate the presence of the described features, integrals, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or collections thereof.

[0032] It should also be understood that the terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the invention. As used in this specification and the appended claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms unless the context clearly indicates otherwise.

[0033] It should also be further understood that the term "and / or" as used in this specification and the appended claims refers to any combination of one or more of the associated listed items and all possible combinations, and includes such combinations.

[0034] The accompanying drawings illustrate various structural schematic diagrams according to embodiments disclosed in this invention. These drawings are not to scale, and some details have been enlarged for clarity, and some details may have been omitted. The shapes of the various regions and layers shown in the drawings, as well as their relative sizes and positional relationships, are merely exemplary and may deviate from reality due to manufacturing tolerances or technical limitations. Furthermore, those skilled in the art can design regions / layers with different shapes, sizes, and relative positions as needed.

[0035] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0036] Example 1 like Figure 1 As shown, the liquid CO2 energy storage coupled with oxygen-enriched combustion system of a coal-fired unit provided by the present invention includes a multi-stage compressor 1, a heat exchanger 2, a liquid CO2 storage tank 3, a cryogenic pump 4, a gasifier 5, a CO2 turbine 6, a gaseous CO2 storage tank 7, a filter 8, a cryogenic air separation nitrogen generator 9, an O2 storage tank 10, a gas mixer 11, an air preheater 12, a dust collector 13, a coal-fired power plant CO2 storage tank 14, and a boiler body 15.

[0037] The system for liquid CO2 energy storage coupled with oxygen-enriched combustion in a coal-fired power unit, as described in this invention, has the following connection method: The CO2 gas filtered through filter 8, along with redundant electricity, is fed into a multi-stage compressor 1 for multi-stage pressurization. The released heat is used to heat the boiler feedwater, reducing the unit's coal consumption for power generation. The compressed CO2 is then fed into a heat exchanger 2, where it exchanges heat with a cold medium before being stored in a liquid CO2 storage tank 3. The liquid CO2 storage tank 3 is connected to a cryogenic pump 4. When energy needs to be released, the liquid CO2 is fed from the liquid CO2 storage tank 3 into the cryogenic pump 4, and then into a vaporizer 5 for heat exchange with a cold medium. The resulting high-pressure, low-temperature CO2 gas is fed into a CO2 turbine 6 to perform work, generating electricity for the grid. The CO2 gas remaining after the CO2 turbine 6 performs work is then stored in a gaseous CO2 storage tank 7. The boiler body 15 undergoes oxygen-enriched combustion. The flue gas produced after combustion is filtered by a dust collector 13 to obtain highly concentrated CO2 gas, which is then stored in a coal-fired power plant CO2 storage tank 14. N2 produced using a cryogenic air separation nitrogen generator 9 is used as an industrial product, while the generated O2 is stored in an O2 storage tank 10. The O2 in the O2 storage tank 10 and the CO2 in the coal-fired power plant CO2 storage tank 14 are then mixed and heated together in a gas mixer 11. The resulting mixed gas is used as primary air, secondary air, and burnout air, heated in an air preheater 12, and then sent to the boiler body 15 for combustion. Simultaneously, the CO2 gas stored in the coal-fired power plant CO2 storage tank 14 can supplement the gaseous CO2 storage tank 7, increasing the energy storage capacity of the liquid CO2 energy storage system when needed.

[0038] Example 2 like Figure 1 As shown, the liquid CO2 energy storage coupled to the oxygen-enriched combustion system of a coal-fired power unit provided by the present invention includes a multi-stage compressor 1, a heat exchanger 2, a liquid CO2 storage tank 3, a cryogenic pump 4, a gasifier 5, a CO2 turbine 6, a gaseous CO2 storage tank 7, a filter 8, a cryogenic air separation nitrogen generator 9, an O2 storage tank 10, a gas mixer 11, an air preheater 12, a dust collector 13, a coal-fired power plant CO2 storage tank 14, and a boiler body 15. The inlet of the multi-stage compressor 1 is connected to the heat exchanger 2, and the outlet of the heat exchanger 2 is connected to the liquid CO2 storage tank 3. The liquid CO2 storage tank 3 is connected to the gasifier 5 through the cryogenic pump 4, and the gasifier 5 is connected to the heat exchanger 6. 2. The high-pressure, low-temperature CO2 gas outlet of the gasifier 5 is connected to the inlet of the CO2 turbine 6. The outlet of the CO2 turbine 6 is connected to the gaseous CO2 storage tank 7. The gaseous CO2 storage tank 7 is connected to the multi-stage compressor 1 through the filter 8. The O2 outlet of the cryogenic air separation nitrogen generator 9 is connected to the O2 storage tank 10. The flue gas from the boiler body 15 is connected to the coal-fired power plant CO2 storage tank 14 after being dusted by the dust collector 13. The outlets of the O2 storage tank 10 and the coal-fired power plant CO2 storage tank 14 are connected to the gas mixer 11. The outlet of the gas mixer 11 is connected to the boiler body 15 through the air preheater 12 installed in the tail flue of the boiler body 15.

[0039] In this embodiment, redundant electricity is used to perform work on the multi-stage compressor 1.

[0040] In this embodiment, the multi-stage compressor 1 increases the pressure of CO2 by utilizing the principle of multi-stage compression.

[0041] In this embodiment, the heat released by the multi-stage compressor 1 is used to heat the boiler feedwater.

[0042] In this embodiment, the cryogenic air separation nitrogen generator 9 is used to cryogenically cool the air and separate O2 and N2 by utilizing the difference in liquefaction pressure.

[0043] In this embodiment, the N2 produced by the cryogenic air separation nitrogen generator 9 is used as an industrial product.

[0044] In this embodiment, the electricity generated by the CO2 turbine 6 after doing work is connected to the power grid.

[0045] In this embodiment, the CO2 gas stored in the coal-fired power plant CO2 storage tank 14 serves as a supplement to the gaseous CO2 storage tank 7.

[0046] Example 3 like Figure 1 As shown, the method for coupling liquid CO2 energy storage with oxygen-enriched combustion in a coal-fired power unit provided by the present invention includes: The CO2 gas filtered by filter 8, along with redundant electricity, is fed into multi-stage compressor 1 for multi-stage pressurization. The compressed CO2 is fed into heat exchanger 2, where it exchanges heat with the cooling medium, and then into liquid CO2 storage tank 3 for storage.

[0047] Liquid CO2 storage tank 3 is connected to cryogenic pump 4. When energy needs to be released, liquid CO2 is fed from liquid CO2 storage tank 3 into cryogenic pump 4, and then into vaporizer 5 to exchange heat with the cold medium. The resulting high-pressure cryogenic CO2 gas is fed into CO2 turbine 6 to do work, generating electricity for grid connection. The CO2 gas produced by the CO2 turbine 6 is then passed into the gaseous CO2 storage tank 7 for storage.

[0048] The boiler body 15 undergoes oxygen-enriched combustion. After the flue gas produced by combustion is removed by the dust collector 13, it can obtain CO2 gas with extremely high concentration, which is then introduced into the coal-fired power plant CO2 storage tank 14 for storage.

[0049] The N2 produced by the cryogenic air separation nitrogen generator 9 is used as an industrial product, while the generated O2 is stored in the O2 storage tank 10.

[0050] The O2 in the O2 storage tank 10 and the CO2 in the coal-fired power plant CO2 storage tank 14 are fed into the gas mixer 11 for mixing and heating. The resulting mixed gas is fed into the air preheater 12 as primary air, secondary air and burnout air, and then sent to the boiler body 15 for combustion.

[0051] The CO2 gas stored in the coal-fired power plant CO2 storage tank 14 can supplement the gaseous CO2 storage tank 7 and can increase the energy storage capacity of the liquid CO2 energy storage system when needed.

[0052] The key points of this invention are as follows: A system and method for coupling liquid CO2 energy storage with oxygen-enriched combustion in a coal-fired power unit, including a multi-stage compressor, heat exchanger, liquid CO2 storage tank, cryogenic pump, gasifier, CO2 turbine, gaseous CO2 storage tank, filter, cryogenic air separation nitrogen generator, O2 storage tank, gas mixer, air preheater, dust collector, coal-fired power plant CO2 storage tank, and boiler body.

[0053] The key point of this invention is that by using a liquid CO2 energy storage system as a supplement to the coal-fired power system, it is possible to achieve smooth power output during rapid load increases and decreases and rapid fluctuations in unit load.

[0054] The key point of this invention is that the CO2 gas stored in the coal-fired power plant CO2 storage tank can be used as a supplement to the gaseous CO2 storage tank, and can increase the energy storage capacity of the liquid CO2 energy storage system when needed.

[0055] The key point of this invention is that the coal-fired unit adopts an oxygen-enriched combustion mode, which greatly reduces carbon emissions and can be efficiently coupled with a liquid CO2 energy storage system.

[0056] The key point of this invention is that the coupled system can simultaneously produce chemical products such as O2, N2, CO2, electricity and steam, realizing chemical polygeneration.

[0057] The key point of this invention is that the heat generated when CO2 at room temperature and pressure is compressed by a multi-stage compressor is used to preheat the boiler feedwater, which can reduce the coal consumption for power generation of the unit.

[0058] The key point of this invention is that CO2 and O2 can be mixed in any proportion in the gas mixer, which can increase the proportion of O2 and promote the combustion of difficult-to-burn fuels.

[0059] The key point of this invention is that liquid CO2 energy storage has a high energy density and a stable CO2 source, which can further improve the efficiency of industrial production in the system.

[0060] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered illustrative and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the scope of the invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0061] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can be appropriately combined to form other embodiments that can be understood by those skilled in the art. The above content is only for illustrating the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made based on the technical concept proposed in this invention shall fall within the scope of protection of the claims of this invention.

Claims

1. A system for liquid CO2 energy storage coupled with oxygen-enriched combustion in a coal-fired power unit, characterized in that, This includes multi-stage compressors, heat exchangers, liquid CO2 storage tanks, cryogenic pumps, vaporizers, CO2 turbines, gaseous CO2 storage tanks, filters, cryogenic air separation nitrogen production equipment, O2 storage tanks, gas mixers, air preheaters, dust collectors, coal-fired power plant CO2 storage tanks, and boiler bodies. The inlet of the multistage compressor is connected to the heat exchanger, the outlet of the heat exchanger is connected to the liquid CO2 storage tank, the liquid CO2 storage tank is connected to the vaporizer via a cryogenic pump, the vaporizer is interconnected with the heat exchanger, the high-pressure cryogenic CO2 gas outlet of the vaporizer is connected to the inlet of the CO2 turbine, the outlet of the CO2 turbine is connected to the gaseous CO2 storage tank, and the gaseous CO2 storage tank is connected to the multistage compressor via a filter. The O2 outlet of the cryogenic air separation nitrogen generator is connected to the O2 storage tank. The flue gas from the boiler body is connected to the coal-fired power plant CO2 storage tank after being dedusted by a dust collector. The outlets of the O2 storage tank and the coal-fired power plant CO2 storage tank are connected to the gas mixer. The outlet of the gas mixer is connected to the boiler body through an air preheater installed in the flue at the tail end of the boiler body.

2. The system for liquid CO2 energy storage coupled with oxygen-enriched combustion in a coal-fired unit according to claim 1, characterized in that, Redundant current is used to power multi-stage compressors.

3. The system for liquid CO2 energy storage coupled with oxygen-enriched combustion in a coal-fired unit according to claim 1, characterized in that, A multistage compressor increases the pressure of CO2 by using the principle of multistage compression.

4. The system for liquid CO2 energy storage coupled with oxygen-enriched combustion in a coal-fired unit according to claim 1, characterized in that, The heat released by the multi-stage compressor is used to heat the boiler feedwater.

5. The system for liquid CO2 energy storage coupled with oxygen-enriched combustion in a coal-fired unit according to claim 1, characterized in that, Cryogenic air separation nitrogen generators are used to cryogenically cool air and separate O2 and N2 by utilizing the difference in liquefaction pressure.

6. The system for liquid CO2 energy storage coupled with oxygen-enriched combustion in a coal-fired unit according to claim 1, characterized in that, The N2 produced by cryogenic air separation nitrogen production equipment is used as an industrial product.

7. The system for liquid CO2 energy storage coupled with oxygen-enriched combustion in a coal-fired unit according to claim 1, characterized in that, The electricity generated by the CO2 turbine after it does work is connected to the power grid.

8. The system for liquid CO2 energy storage coupled with oxygen-enriched combustion in a coal-fired unit according to claim 1, characterized in that, The CO2 gas stored in the CO2 storage tank of the coal-fired power plant serves as a supplement to the gaseous CO2 storage tank.

9. A method for coupling liquid CO2 energy storage with oxygen-enriched combustion in a coal-fired power unit, characterized in that, This method, based on the liquid CO2 energy storage coupled with oxygen-enriched combustion system of a coal-fired unit as described in claim 1, includes: Filtered CO2 gas is fed into a multi-stage compressor along with redundant electricity for multi-stage pressurization, releasing heat to heat boiler feedwater. The compressed CO2 then enters a heat exchanger to exchange heat with a refrigerant before being stored in a liquid CO2 storage tank. When energy needs to be released, the liquid CO2 is pumped from the storage tank to a cryogenic pump, and then to a vaporizer for further heat exchange with the refrigerant. The resulting high-pressure, low-temperature CO2 gas is fed into a CO2 turbine to generate electricity for the grid. The CO2 gas remaining after the turbine's operation is then returned to a gaseous CO2 storage tank. The process involves: The boiler body undergoes oxygen-enriched combustion; the resulting flue gas is then filtered by a dust collector to obtain CO2 gas with a concentration of over 90%, which is then stored in a coal-fired power plant CO2 storage tank; N2 produced using a cryogenic air separation nitrogen generator is used as an industrial product, while the generated O2 is stored in an O2 storage tank; the O2 in the O2 storage tank and the CO2 in the coal-fired power plant CO2 storage tank are then mixed and heated together in a gas mixer; the resulting mixed gas is used as primary air, secondary air, and burnout air, heated in an air preheater, and then sent to the boiler body for combustion.

10. The method for coupling liquid CO2 energy storage with oxygen-enriched combustion in a coal-fired power unit according to claim 9, characterized in that, The CO2 gas stored in the CO2 storage tank of the coal-fired power plant serves as a supplement to the gaseous CO2 storage tank.

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