Liquefied air energy storage oxygen production integration method and system

Abstract

The application discloses a liquefied air energy storage oxygen production integrated method and system, and the system comprises an air liquefaction unit, a separation oxygen production unit, a gasification power generation unit and a cold exchange unit. The air liquefaction process is a process of pressurizing, cooling and expanding and liquefying air, and the power used is provided by green power. The separation oxygen production process is completed in a rectifying tower, and the stored oxygen-rich liquefied air provides continuous feed for the rectifying tower. The gasification power generation is a process of using the stored oxygen-poor liquefied air to be gasified, overheated and expanded to generate power when there is no green power. The cold exchange in the whole system is a multi-grade and dynamic cold exchange process. The application realizes that the power and oxygen demand in the coal chemical process are all provided by green power, and the energy consumption and carbon emission in the coal chemical process are greatly reduced. Meanwhile, the efficient recycling and utilization of the cold in the liquefied air energy storage oxygen production integrated system are realized, the complementary application among the integrated processes is optimized, and the overall circulation efficiency of the system is improved.

Description

Technical Field

[0001] This invention relates to the field of renewable energy / green electricity and coal chemical technology, specifically to an integrated method and system for oxygen production from liquefied air storage. Background Technology

[0002] Renewable energy is a green and low-carbon energy source, which is of great significance for improving the energy structure, protecting the ecological environment, addressing climate change, and achieving sustainable economic and social development. Traditional coal chemical industry, as a typical "high-energy-consuming and high-emission" industry, must accelerate research on the large-scale application of renewable energy in the coal chemical industry, promote the orderly reduction and replacement of coal by renewable energy, and achieve green transformation and upgrading in order to avoid being eliminated in the future.

[0003] Because renewable energy power generation is inherently volatile and unstable, while coal chemical industry demands extremely stringent long-term stable operation, the development of large-scale energy storage technologies is imperative to resolve this contradiction. Existing large-scale energy storage technologies are typically represented by pumped hydro storage, compressed air storage (CASP), and liquefied air storage (LAES). Pumped hydro storage has a large capacity and mature technology, but its initial investment cost is high, and its construction is limited by factors such as water resources and site availability, thus limiting its application. Compressed air storage requires the use of abandoned mines or existing large-capacity underground spaces as high-pressure storage containers, which also restricts its development. Liquefied air storage (LAES) technology uses liquid air as the energy storage medium, is not constrained by environmental factors, and has advantages such as large storage capacity, high energy density, safety, environmental friendliness, small footprint, and flexible regulation.

[0004] By connecting an "energy storage module" to the coal chemical industry, fluctuating green electricity can be converted into stable power output, which can meet the requirement of using green electricity for the entire coal chemical process and achieve "energy saving and consumption reduction" and "carbon emission reduction" in the coal chemical process.

[0005] Chinese patent CN112145248A discloses an external compression air separation process with energy storage, power generation, and material recovery functions. This process integrates a cryogenic liquid air storage system and an air-based energy release power generation system into a conventional external compression air separation process, forming a novel air separation process that combines gas separation, liquid air storage, air-based power generation, and material recovery. This achieves large-scale energy storage characteristics for air separation equipment and technology. The process utilizes inexpensive off-peak electricity to liquefy and store gas resources beyond the air separation capacity requirements. During energy release, a cold storage cycle and the use of waste heat from compression ensure the full recovery of cold energy released from the stored material and its gasification process, generating electricity. This reduces the air separation equipment's demand for peak-hour electricity and improves the company's economic efficiency.

[0006] Chinese patent CN210197867U discloses an air separation oxygen generation device for energy storage and release, comprising an air separation oxygen generation device and a nitrogen expansion power generation device. It utilizes air separation variable load technology and liquid nitrogen energy storage power generation technology to stably output oxygen products over a long period and output electricity during peak electricity consumption periods. However, the air separation oxygen generation device in the aforementioned document operates as a continuous and stable process, making it impossible to use entirely green electricity. Therefore, the peak-shaving electricity provided by the nitrogen expansion power generation device cannot be considered green electricity. Furthermore, the nitrogen expansion power generation device operates intermittently, severely impacting the stable operation of the air separation distillation column (the difference in cooling requirements between fully liquid nitrogen extraction and non-liquid nitrogen extraction conditions is significant, causing a substantial shift in the column's equilibrium operating point), making it practically difficult to implement. Summary of the Invention

[0007] In view of this, the main objective of this invention is to provide an integrated method and system for oxygen production using liquefied air storage, which deeply couples air separation oxygen production with liquefied air energy storage, enabling the entire electricity and oxygen demand in coal chemical processes to be provided by green electricity, while significantly reducing energy consumption and carbon emissions in the coal chemical process. By introducing a highly efficient multi-stage dynamic cold storage / release device, the system achieves efficient recovery and utilization of cold energy in the integrated liquefied air energy storage oxygen production system, and optimizes the complementary application between integrated processes, thereby improving the overall cycle efficiency of the system.

[0008] To achieve the above-mentioned objectives, the present invention adopts the following technical solution: a liquefied air energy storage and oxygen generation integrated system, comprising at least:

[0009] The air liquefaction unit includes a filter (1), a booster (2), a molecular sieve (3), a main compressor (4), a turbine expander (5), and an oxygen-deficient air compressor (8). The raw material air passes through the filter (1), booster (2), molecular sieve (3), and main compressor (4) in sequence to obtain pressurized purified air. The purified air is cooled and then passes through the turbine expander (5) to obtain a gas phase flow and a liquid phase flow. The gas phase flow is pressurized by the oxygen-deficient air compressor (8) and cooled to obtain a liquid.

[0010] The oxygen generation unit includes an oxygen-enriched liquid air storage tank (6), an oxygen-enriched liquid air pump (7), a lower distillation column (9), a main cooler (10), an upper distillation column (11), a subcooler (12), and a liquid oxygen pump (14). The liquid phase flows into the oxygen-enriched liquid air storage tank (6), is pressurized by the oxygen-enriched liquid air pump (7), and then enters the lower distillation column (9). The main cooler (10) serves as the condenser for the lower distillation column (9) and the reboiler for the upper distillation column (11), and is connected to both. The oxygen-enriched liquid air obtained from the lower distillation column (9) is then passed through the subcooler (12). After supercooling, it enters the upper distillation column (11) for further distillation; part of the low-pressure nitrogen obtained from the lower distillation column (9) is used as a heat source and enters the main cooler (10), and the other part is reheated to obtain low-pressure nitrogen; part of the pure liquid nitrogen at the outlet of the main cooler (10) is used as reflux liquid, and part of it is supercooled by the cooler (12) and enters the top of the upper distillation column (11) as reflux liquid; the liquid oxygen obtained from the upper distillation column (11) is compressed by the liquid oxygen pump (14) and reheated to obtain high-pressure oxygen;

[0011] The gasification power generation unit includes an oxygen-deficient liquid air storage tank (16), an oxygen-deficient liquid air pump (17), a superheater (18), and an expansion generator (19). The liquid obtained after cooling by the air liquefaction unit enters the oxygen-deficient liquid air storage tank (16), and is pressurized by the oxygen-deficient liquid air pump (17) and then vaporized to obtain oxygen-deficient air which enters the superheater (18). The superheated oxygen-deficient air then enters the expansion generator (19) to generate electricity.

[0012] The cold exchange unit includes multiple series-connected cold storage / release devices (20) for cold storage and release; the air purification cooling and gas phase flow cooling in the air liquefaction unit, the oxygen and nitrogen reheating in the oxygen separation unit, and the oxygen-deficient liquid airization in the gasification power generation unit are all carried out in the cold exchange unit.

[0013] According to the device of the present invention, the air liquefaction unit further includes a throttle valve (15) for throttling the cooled liquid into the oxygen-deficient liquid air storage tank (16).

[0014] According to the device of the present invention, the booster (2) and the main compressor (4) of the air liquefaction unit are both driven by green electricity provided by renewable energy.

[0015] According to the apparatus of the present invention, the oxygen separation unit further includes a nitrogen throttling valve (13). A portion of the liquid nitrogen from the outlet of the main cooler (10) is subcooled by the cooler (12) and then throttled by the throttling valve (13) into the top of the upper distillation column (11) as its reflux liquid.

[0016] According to the apparatus of the present invention, the waste nitrogen gas at the top of the distillation column (11) is vented after the cold energy is recovered by the cold energy exchange unit.

[0017] According to the apparatus of the present invention, in the oxygen separation unit, the low-grade waste heat of the superheater (18) comes from the exhaust gas from coal chemical industry and the heat recovered after the compressor.

[0018] According to the device of the present invention, the air liquefaction unit operates only when green electricity is available, and performs an intermittent operation process; the oxygen separation unit performs a continuous operation process; and the gasification power generation unit starts when there is no green electricity, and also performs an intermittent operation process.

[0019] According to the device of the present invention, when cold storage is performed, the cold storage / release device (20) is a cold storage unit, including a multi-stage cold storage bed with a cold storage medium for the entry of cold fluid. When the cold energy is stored in the first-stage cold storage bed and reaches the maximum cold storage capacity, the cold fluid circulates between the various stages of the cold storage bed to perform a cold storage cycle. In a specific embodiment, the multi-stage cold storage bed may include a cryogenic bed (first stage), a medium-cold bed (second stage), and a pre-cooling bed (third stage). The cryogenic bed serves as the first-stage cold storage bed to store the cold energy, and the third-stage pre-cooling bed is used to ensure that the outlet temperature of the cold fluid is close to room temperature, so as to achieve the purpose of fully recovering the cold energy in the cold fluid.

[0020] According to the device of the present invention, when cooling is performed, the cooling storage / cooling device (20) is a cooler, including a multi-stage cooling bed with a cooling storage medium for the entry of hot fluid. When heat is released and the maximum cooling capacity is reached in the first-stage cooling bed, the hot fluid circulates between the stages of the cooling bed to perform a cooling cycle. In a specific embodiment, the multi-stage cooling bed may include cooling bed I, cooling bed II, and cooling bed III. Cooling bed I serves as the first-stage cooling bed to release cooling capacity, and cooling bed III serves as the last stage to ensure that the outlet hot fluid is sufficiently cooled and the temperature is reduced to the minimum, so that the hot fluid absorbs cooling capacity to the maximum extent during the cooling process.

[0021] Another aspect of the present invention provides an integrated method for liquefied air energy storage and oxygen generation, comprising the following steps:

[0022] The raw air enters the air liquefaction unit, where it is filtered by the filter (1) to remove impurities. After being compressed by the booster (2), it enters the molecular sieve (3) to adsorb carbon dioxide, hydrocarbons and moisture from the air. The adsorbed air is then pressurized by the main compressor (4), cooled by the cold exchange unit, expanded and cooled by the turbine expander (5), and the resulting gas-liquid two-phase flow enters the oxygen-enriched liquid air storage tank (6). The liquid phase oxygen-enriched liquid air is stored in the tank, while the gas phase oxygen-deficient liquid air is further pressurized by the oxygen-deficient liquid air compressor (8) and cooled to liquid by the cold exchange unit.

[0023] Oxygen-enriched liquid air is separated and used to produce oxygen. The liquid flow in the oxygen-enriched liquid air storage tank (6) is pressurized by the oxygen-enriched liquid air pump (7) and enters the lower distillation column (9). The rising gas in the lower distillation column (9) increases the nitrogen content by contacting the reflux liquid nitrogen provided by the main cooler (10). Another part of the liquid nitrogen in the main cooler (10) is sent to the upper distillation column (11) as reflux liquid after heat exchange in the subcooler (12). The oxygen-enriched liquid air in the lower distillation column (9) is subcooled by the cooler (12) and then enters the upper distillation column (11) for further distillation. The liquid oxygen obtained from the upper distillation column (11) is compressed by the liquid oxygen pump and reheated by the cold exchange unit to obtain high-pressure oxygen. Part of the low-pressure nitrogen obtained from the lower distillation column (9) is used as a heat source and enters the main cooler (10). The other part is reheated by the cold exchange unit to obtain low-pressure nitrogen.

[0024] The liquid obtained after cooling by the air liquefaction unit enters the oxygen-deficient liquid air storage tank (16), and after being pressurized by the oxygen-deficient liquid air pump (17), it is vaporized by the cold exchange unit to obtain oxygen-deficient air which enters the superheater (18). The superheated oxygen-deficient air enters the expansion generator (19) to generate electricity. The low-grade waste heat of the superheater (18) comes from the exhaust gas emitted by the coal chemical industry and the heat recovered after the compressor.

[0025] According to the method of the present invention, the liquid obtained after cooling in the air liquefaction unit is throttled into the oxygen-deficient liquid air storage tank (16) through the throttle valve (15).

[0026] According to the method of the present invention, a portion of the pure liquid nitrogen in the main cooler (10) is cooled by the cooler (12) and throttled by the nitrogen throttling valve (13) into the top of the distillation column (11) as its reflux liquid.

[0027] According to the method of the present invention, the sludge nitrogen gas at the top of the distillation column (11) is vented after the cold energy is recovered by the cold energy exchange unit.

[0028] According to the method of the present invention, the air liquefaction unit obtains oxygen-rich liquid air and oxygen-deficient liquid air through stepwise liquefaction. In the air liquefaction unit, the air separation is compressed, cooled, and expanded to liquefy, and can be coarsely separated into oxygen-rich liquid air and oxygen-deficient air. The oxygen-deficient air is further compressed and cooled to obtain oxygen-deficient liquid air.

[0029] Compared with the prior art, the present invention has the following advantages:

[0030] 1. This invention provides a highly efficient integrated technology solution for liquefied air energy storage and oxygen production. The integrated process involves air liquefaction, oxygen separation, gasification power generation, and cold energy exchange. When renewable energy is used for power generation, a portion of the green electricity powers the coal chemical plant, and the remainder is used for air liquefaction and oxygen separation. When renewable energy is unavailable, the oxygen-deficient liquid air stored in this invention is gasified, superheated, and expanded to generate electricity, providing peak-shaving power for the coal chemical plant. The stored oxygen-enriched liquid air provides continuous feed for oxygen separation, ensuring a stable oxygen supply.

[0031] 2. Both traditional air separation oxygen generation devices and traditional liquefied air energy storage devices use air as the medium. This invention combines the air liquefaction processes of the two devices, which can significantly reduce the investment in energy storage devices.

[0032] 3. This invention uses a stepped liquefaction technology to coarsely separate air, controlling the air pressure during compression to not exceed the critical pressure. Clean air is partially liquefied after pressurization, cooling, and throttling expansion. Taking a 50% liquefaction rate as an example, it can generate oxygen-enriched liquid air with 30% oxygen content and oxygen-lean liquid air with 10% oxygen content. Feeding oxygen-enriched liquid air can significantly reduce the height of the distillation column, the number of trays, and the cost of oxygen production in the oxygen separation unit. Oxygen-lean liquid air power generation greatly reduces oxygen loss during energy storage and power generation. The liquefaction rate of the coarsely separated air can be adjusted according to the required oxygen and power generation of the device.

[0033] 4. In this invention, an oxygen-enriched liquid air storage tank is added to the oxygen separation unit, which ensures the continuity of operation of the oxygen separation unit while the air liquefaction unit uses all green electricity.

[0034] 5. In this invention, air liquefaction and oxygen-deficient liquid air liquefaction are asynchronous and are intermittent operations, while liquid oxygen liquefaction is a continuous operation. Therefore, the system involves multi-stage dynamic energy exchange processes. Furthermore, since both the energy exchange mediums are air, and air is clean, environmentally friendly, and pollution-free, a direct-contact packed bed can be used for energy exchange in the system.

[0035] 6. The multi-stage dynamic cold storage / release device proposed in this invention consists of multiple packed bed cold storage / release units. During the cold storage process, by connecting multiple cold storage units in series, the cold storage capacity of the first-stage cold storage unit reaches its maximum value, and the outlet fluid temperature of the last-stage cold storage unit is close to room temperature, ensuring sufficient cold recovery. By sequentially switching the cold fluid inlet position, each stage of the cold storage unit can reach its maximum cold storage capacity, thereby reducing the amount of cold storage material used, reducing the size of the cold storage unit, and improving the cold recovery efficiency. After the cold storage unit reaches its maximum cold storage capacity, it is switched out of the cold storage cycle and becomes a release unit, entering the release cycle. The principle of the release cycle is the same as above. By connecting multiple release units in series, the cold release capacity of the first-stage release unit reaches its maximum value, and the outlet fluid temperature of the last-stage release unit is close to the minimum temperature of the release unit, ensuring sufficient cold release, and the outlet temperature of the cooled fluid is kept constant at the minimum temperature; and by sequentially switching the cold fluid inlet position, each stage of the release unit can reach its maximum release capacity. When the first-stage coolant approaches room temperature, it is cut off and becomes a cold storage unit, entering the cold storage cycle process.

[0036] In summary, this invention represents a deep technological coupling of an air separation oxygen production unit and liquefied air energy storage in coal chemical industry. This enables the simultaneous supply of stable electricity and oxygen from renewable energy sources to the coal chemical process. Furthermore, by merging the air liquefaction processes of both technologies, the investment in energy storage devices is significantly reduced. The efficiency of this integrated technology is closely related to the full recovery of cold energy within the system. Air separation oxygen production is a steady-state, multi-grade cold energy exchange; coupled with liquefied air energy storage, it becomes a multi-stage dynamic cold energy exchange. Therefore, this invention proposes a highly efficient multi-stage dynamic cold storage / release device, aiming to achieve full cold energy exchange in the integrated liquefied air energy storage oxygen production process, optimize the complementary application between air separation and liquefied air energy storage processes, and improve cold energy recovery efficiency and the overall efficiency of the integrated system. Attached Figure Description

[0037] Figure 1 This is a schematic diagram of an integrated system for liquefied air energy storage and oxygen generation, as exemplified by the present invention.

[0038] Figure 2 This is a schematic diagram of the cold storage process in a multi-stage dynamic cold storage / release device.

[0039] Figure 3 This is a schematic diagram of the cooling process of a multi-stage dynamic cold storage / cooling release device.

[0040] Labeling Explanation: 1. Filter, 2. Booster, 3. Molecular sieve, 4. Main compressor, 5. Turbine expander, 6. Oxygen-enriched liquid air storage tank, 7. Oxygen-enriched liquid air pump, 8. Oxygen-lean air compressor, 9. Lower distillation column, 10. Main cooler, 11. Upper distillation column, 12. Subcooler, 13. Nitrogen throttle valve, 14. Liquid oxygen pump, 15. Air throttle valve, 16. Oxygen-lean liquid air storage tank, 17. Oxygen-lean liquid air pump, 18. Superheater, 19. Expander generator, 20. Cold storage / cooling device, 201. Deep cooling bed, 202. Intercooling bed, 203. Precooling bed, 301. Cooling bed I, 302. Cooling bed II, 303. Cooling bed III. Detailed Implementation

[0041] Embodiments of the present invention are described in detail below. Examples of these embodiments are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0042] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., 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 the invention and for 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 the invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0043] Unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing" should be interpreted broadly. For example, they can refer to fixed connections or detachable connections; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; and connections within two components or interactions between two components. Those skilled in the art can understand the specific meaning of these terms in this invention based on the specific circumstances.

[0044] The main idea of ​​this invention is to provide an integrated method and system for liquefied air energy storage and oxygen production, mainly including air liquefaction, oxygen separation, gasification power generation, and cold energy exchange processes. The air liquefaction process involves pressurizing, cooling, and expanding air to liquefy it; all electricity used is provided by green energy sources, and it is an intermittent operation. The oxygen separation process is completed in a distillation column, with stored oxygen-enriched liquid air providing a continuous feed to the distillation column; the entire process is a continuous and stable operation. Gasification power generation, when green energy is unavailable, utilizes the stored oxygen-lean liquid air for air liquefaction, superheating, and expansion to generate electricity; this is also an intermittent operation. The cold energy exchange in the entire system is a multi-grade, dynamic cold energy exchange process, carried out through multiple cold storage / release units.

[0045] Based on this, refer to Figure 1 This invention provides an integrated system for liquefied air energy storage and oxygen generation, comprising:

[0046] The air liquefaction unit includes a filter (1), a booster (2), a molecular sieve (3), a main compressor (4), a turbine expander (5), and an oxygen-deficient air compressor (8). The raw material air passes through the filter (1), booster (2), molecular sieve (3), and main compressor (4) in sequence to obtain pressurized purified air. The purified air is cooled and then passes through the turbine expander to obtain a gas phase flow and a liquid phase flow. The gas phase flow is pressurized by the oxygen-deficient air compressor (8) and cooled to obtain a liquid.

[0047] The oxygen generation unit includes an oxygen-enriched liquid air storage tank (6), an oxygen-enriched liquid air pump (7), a lower distillation column (9), a main cooler (10), an upper distillation column (11), a subcooler (12), and a liquid oxygen pump (14). The liquid phase flows into the oxygen-enriched liquid air storage tank (6), is pressurized by the oxygen-enriched liquid air pump (7), and then enters the lower distillation column (9). The main cooler (10) serves as the condenser for the lower distillation column (9) and the reboiler for the upper distillation column (11), and is connected to both. A portion of the pure liquid nitrogen in the main cooler (10) is used as the reflux liquid for the lower distillation column (9), and the other portion of the pure liquid nitrogen is cooled by the cooler (12) and then passes through a throttling valve (13). After throttling, the liquid air is sent to the upper distillation column (11) as reflux; the oxygen-rich liquid air in the lower distillation column (9) is subcooled by the cooler (12) and then enters the upper distillation column (11) for further distillation; the liquid oxygen obtained in the upper distillation column (11) is compressed by the liquid oxygen pump and reheated to obtain high-pressure oxygen; part of the low-pressure nitrogen obtained in the lower distillation column (9) is used as a heat source and enters the main cooler (10), and the other part is reheated to obtain low-pressure nitrogen;

[0048] The gasification power generation unit includes an oxygen-deficient liquid air storage tank (16), an oxygen-deficient liquid air pump (17), a superheater (18), and an expansion generator (19). The liquid obtained after cooling by the air liquefaction unit enters the oxygen-deficient liquid air storage tank (16), and is pressurized by the oxygen-deficient liquid air pump (17) and then vaporized to obtain oxygen-deficient air which enters the superheater (18). The superheated oxygen-deficient air enters the expansion generator (19) to generate electricity. The low-grade waste heat of the superheater (18) comes from the exhaust gas from coal chemical industry and the heat recovered after the compressor.

[0049] The cold exchange unit includes multiple series-connected cold storage / release devices (20) for cold storage and release; the air purification cooling and gas phase flow cooling in the air liquefaction unit, the oxygen and nitrogen reheating in the oxygen separation unit, and the oxygen-deficient liquid airization in the gasification power generation unit are all carried out in the cold exchange unit.

[0050] In this invention, the booster (2) and main compressor (4) of the air liquefaction unit are both driven by green electricity provided by renewable energy. Through the device in this invention, green electricity is converted into stable electricity to power the entire coal chemical plant, achieving the goal of energy conservation and emission reduction.

[0051] Preferably, the air liquefaction unit further includes an air throttle valve (15) for throttling the cooled liquid into the oxygen-deficient liquid air storage tank (16).

[0052] Preferably, the waste nitrogen gas at the top of the distillation column (11) is vented after the cold energy is recovered by the cold energy exchange unit.

[0053] The specific structure and operating parameters of each unit are described in detail below:

[0054] Air liquefaction unit: The air liquefaction process is only activated when green electricity is available. The raw air from the atmosphere is filtered by a filter (1) to remove dust and other mechanical impurities, then compressed by an air booster (2) and enters a molecular sieve (3) that is switched on. Carbon dioxide, hydrocarbons and moisture in the air are adsorbed. The purified air is pressurized by the main compressor (4) and cooled by a multi-stage dynamic cold storage / release device (20). After being expanded and cooled by a turbine expander (5), the gas-liquid two-phase flow enters an oxygen-rich liquid air storage tank (6) at atmospheric pressure. The liquid phase oxygen-rich liquid air is stored in the tank, and the gas phase oxygen-deficient liquid air is further pressurized by an oxygen-deficient liquid air compressor (8) and cooled to near the dew point by the multi-stage dynamic cold storage / release device (20). It is then throttled by an air throttle valve (15) and enters an oxygen-deficient liquid air storage tank (16). The booster (2) and the main compressor (4) are both driven by green electricity provided by renewable energy. Therefore, the air liquefaction only operates when green electricity is available and is an intermittent operation.

[0055] Oxygen generation unit: The oxygen-enriched liquid air stored in the oxygen-enriched liquid air storage tank (6) is pressurized by the oxygen-enriched liquid air pump (7) and enters the lower distillation column (9). The rising gas in the lower distillation column (9) increases its nitrogen content by contacting the reflux liquid nitrogen. The required reflux liquid nitrogen comes from the main cooler (10) at the top of the lower column, where oxygen evaporates and nitrogen is condensed. Another part of the pure liquid nitrogen in the main cooler (10) is heat-exchanged in the subcooler (12) and then throttled through the throttle valve (13) and sent to the top of the upper distillation column (11) as reflux liquid. The oxygen-enriched liquid air in the lower distillation column (9) is subcooled by the cooler (12) and then enters the upper distillation column (11) for further distillation. Liquid oxygen is drawn from the bottom of the upper column, compressed in the liquid oxygen pump (14), and reheated in the multi-stage dynamic cold storage / release device (20) to obtain high-pressure oxygen. Low-pressure nitrogen is extracted from the top of the lower distillation column (9), part of which enters the main cooler (10) as a heat source, and the other part is reheated in the multi-stage dynamic cold storage / release device (20) to obtain low-pressure nitrogen. The waste nitrogen at the top of the upper distillation column (11) is vented after the cold energy is recovered by the multi-stage dynamic cold storage / release device (20). Among them, the oxygen production system is a continuous operation process. The oxygen-enriched liquid air storage tank (6) serves as an intermediate buffer tank. When the air liquefaction process stops, it can continue to provide oxygen-enriched liquid air to the oxygen production system, ensuring the continuity of oxygen production in the entire system.

[0056] Gasification Power Generation Unit: The gasification power generation process starts when there is no green electricity. The oxygen-deficient liquid air stored in the oxygen-deficient liquid air storage tank (16) is pressurized by the oxygen-deficient liquid air pump (17) and then gasified in the multi-stage dynamic cold storage / release device (20). The gasified oxygen-deficient air enters the superheater (18). The low-grade waste heat on the other side of the superheater (18) comes from the exhaust gas from the coal chemical industry and the heat recovered after the compressor. The superheated oxygen-deficient air enters the expansion generator (19) to generate electricity. This unit starts when there is no green electricity and is also an intermittent operation.

[0057] Cold exchange unit: The cold exchange in the system is a multi-grade, dynamic cold exchange process, which is completed in a multi-stage dynamic cold storage / release device (20). The multi-stage dynamic cold storage / release device (20) consists of multiple direct-contact packed bed cold storage / release units, each of which is involved in both the cold storage and cold release processes. The cold storage and cold release processes are described in detail below.

[0058] The cold storage process involves oxygen-deficient liquid air vaporization, liquid oxygen vaporization, low-pressure nitrogen reheating, waste nitrogen reheating, and recovery of vented air cooling capacity. As an example, the cold storage unit involved consists of three or more units connected in series. Each cold storage cycle is completed by three or more units connected in series, and the efficiency of each unit is maximized by continuously switching the cold fluid inlet position, thus achieving maximum recovery and utilization of cooling capacity throughout the integrated process. Figure 2Of the four units shown, one is a storage tank that has completed its cooling process. After switching to the next cycle, it becomes the release cooling bed III. See Appendix for the cooling process. Figure 2 Specifically, it includes the following steps:

[0059] Cold fluid at -150℃ to -170℃ sequentially passes through a cryogenic bed, an intermediate bed, and a precooling bed. By adjusting the number of cold storage units and their size and structural design, the outlet fluid temperature of the precooling bed is kept close to ambient temperature. When the outlet temperature of the cryogenic bed 201 approaches the inlet temperature (<5℃), cold storage is considered complete. The inlet and outlet valves of the cold storage unit are then closed, and the cold storage cycle is terminated, preparing for cold release. Simultaneously, the cold fluid inlet is switched to the intermediate bed 202, which then becomes the cryogenic bed 201. The ambient temperature bed layer, now cooled to ambient temperature, is then introduced as the precooling bed 203. This process continues, with the entire cold storage process achieved through the cyclical switching of multiple cold storage units.

[0060] The cooling process involves compressed air cooling and oxygen-deficient air cooling. As an example, the cooling system consists of three or more cooling units connected in series. Each cooling cycle is completed by these three or more cooling units connected in series, and the efficiency of each cooling unit is maximized by continuously switching the hot fluid inlet position, thus maximizing the recovery and utilization of the overall cooling capacity. Figure 3 Of the four units shown, one is a storage tank that has completed its cooling process. After switching to the next cycle, it becomes a precooling bed; see Appendix for the cooling process. Figure 3 Specifically, it includes the following steps:

[0061] A hot fluid at ambient temperature to 40°C sequentially passes through cooling beds I (301), II (302), and III (303). By adjusting the number of coolers and their size and structural design, the outlet fluid temperature of cooling bed III is ensured to be close to the cooler temperature. When the outlet temperature of cooling bed I approaches the inlet temperature (<5°C), cooling is considered complete. The inlet and outlet valves of the cooler are then closed, and the cooler stops its cooling cycle, preparing for cold storage. Simultaneously, the hot fluid inlet is switched to cooling bed II, and the completed cryogenic bed is then introduced as the final stage of cooling. This process continues, with the entire cooling process achieved through the cyclic switching of multiple coolers.

[0062] To make the objectives, technical solutions, and effects of this invention clearer and more explicit, the following references are made to the appendix. Figure 1-3 The system and method flow of the present invention will be further described in detail with reference to specific embodiments.

[0063] The amounts of oxygen-enriched and oxygen-deficient liquid air produced during the air liquefaction process are determined by the oxygen demand and peak-shaving power required by the entire plant / complete coal chemical unit, respectively. The liquefaction rate of the coarse separation process (amount of oxygen-enriched liquid air obtained from coarse separation / total air feed) can be adjusted by the outlet pressure of the air after passing through the main compressor (4) and the temperature of the air exiting the multi-stage dynamic cold storage / cooling device (20). The outlet pressure adjustment range is 2.0MPa~3.2MPa; the temperature adjustment range after cooling is -110℃~-180℃;

[0064] The oxygen-deficient air is pressurized and throttled by the oxygen-deficient air compressor (8) to obtain sufficient cooling capacity, which allows it to be fully liquefied. The higher the outlet pressure of the oxygen-deficient air compressor (8), the more oxygen-deficient liquid air is obtained.

[0065] The process of this invention is briefly described below, taking a 50% liquefaction rate and a 90% oxygen-deficient liquid air yield in the coarse separation process as an example.

[0066] Example 1

[0067] The raw air enters the air liquefaction unit, is filtered by filter (1) to remove dust and other mechanical impurities, and is then compressed to about 0.62 MPa by air booster (2) before entering the molecular sieve (3), where carbon dioxide, hydrocarbons and moisture in the air are adsorbed. After adsorption and purification, the air is pressurized to about 3.2 MPa by the main compressor (4) and then enters the multi-stage dynamic cold storage / release device (20) to be cooled to -140°C. After expansion and cooling by the turbine expander (5), the gas-liquid two-phase flow enters the atmospheric pressure oxygen-enriched liquid air storage tank (6). The liquid phase oxygen-enriched liquid air is stored in the tank, and the gas phase oxygen-deficient air is further pressurized to about 6.5 MPa by the oxygen-deficient air compressor (8) and enters the multi-stage dynamic cold storage / release device (20) to be cooled to near the dew point. It is then throttled by the throttle valve (15) and enters the oxygen-deficient liquid air storage tank (16).

[0068] Oxygen-enriched liquid air is separated to produce oxygen. The oxygen content of the oxygen-enriched liquid air stored in the oxygen-enriched liquid air storage tank (6) is about 30%. After being pressurized to 0.2 MPa by the oxygen-enriched liquid air pump (7), it enters the lower distillation column (9). The rising gas in the lower distillation column (9) increases the nitrogen content by contacting the reflux liquid nitrogen. The required reflux liquid nitrogen comes from the main cooler (10) at the top of the lower column, where oxygen is evaporated and nitrogen is condensed. Another part of the pure liquid nitrogen in the main cooler (10) is sent to the upper distillation column (11) as reflux liquid after heat exchange in the subcooler (12). The oxygen-enriched liquid air in the lower distillation column (9) is subcooled to -179°C by the cooler (12) and then throttled by the throttle valve (13) to enter the top of the upper distillation column (11) as its reflux liquid. Liquid oxygen is drawn from the bottom of the upper column and compressed to 8.7 MPaA in the liquid oxygen pump (14). After being reheated in the multi-stage dynamic storage / release device (20), high-pressure oxygen is obtained. Low-pressure nitrogen is drawn from the top of the lower distillation column (9). Part of it enters the main cooler (10) as a heat source, and the other part is reheated in the multi-stage dynamic storage / release device (20) to obtain low-pressure nitrogen. The waste nitrogen at the top of the column is vented after recovering its cold energy in the multi-stage dynamic storage / release device (20).

[0069] The oxygen-deficient liquid air power generation is achieved by storing oxygen-deficient liquid air in a storage tank (16) with an oxygen content of about 10%. After being increased by the oxygen-deficient liquid air pump (17), the liquid air is vaporized in a multi-stage dynamic cold storage / release device (20). The vaporized oxygen-deficient air enters the superheater (18). The low-grade waste heat on the other side of the superheater (18) comes from the exhaust gas from the coal chemical industry and the heat recovered after the compressor. The superheated oxygen-deficient air enters the expansion generator (19) to generate electricity.

[0070] This embodiment can transform the fluctuating power input from large-scale renewable energy sources into a stable and continuous output of oxygen and electricity, enabling the entire power and oxygen demand of coal chemical processes to be provided by green electricity, and significantly reducing energy consumption and carbon emissions in coal chemical industry. Assuming the green electricity lasts for 12 hours / day, constructing a 25MW / 300MWh liquefied air energy storage integrated unit can meet all the power and oxygen needs of a 300,000-ton coal-to-methanol plant, while also significantly reducing fuel coal consumption and low-concentration CO2 emissions. Specific data are as follows:

[0071] 1) Power consumption changed from 25MW to 0 (all electricity is green).

[0072] 2) Fuel coal consumption changed from 24 t / h to 4 t / h

[0073] 3) Low-concentration CO2 emissions reduced by 36 kNm 3 / h→6kNm 3 / h

[0074] By developing multi-stage dynamic cold storage / release devices, the storage / release capacity and efficiency of each device are maximized, achieving a cold energy recovery rate of over 90% in the system. Furthermore, by optimizing the complementary application of integrated processes, the overall efficiency of the liquefied air energy storage and oxygen production integrated system is achieved to over 65%.

[0075] The process of this invention includes an air liquefaction unit, a separation oxygen generation unit, a gasification power generation unit, and a cold energy exchange unit. This invention innovatively utilizes the combination of devices within each unit and has developed optimized settings for process parameters. Although the specific structure of each device is not further described in detail, those skilled in the art can understand its specific structure based on its functional description, so it will not be described in detail here.

[0076] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art can make other variations or modifications based on the above description. It is impossible to exhaustively list all embodiments here. All obvious variations or modifications derived from the technical solutions of the present invention are within the spirit and scope of the present invention.

Claims

1. A liquefied air energy storage oxygen production integrated system, characterized by: At least including: The air liquefaction unit includes a filter (1), a booster (2), a molecular sieve (3), a main compressor (4), a turbine expander (5), and an oxygen-deficient air compressor (8). The raw material air passes through the filter (1), booster (2), molecular sieve (3), and main compressor (4) in sequence to obtain pressurized purified air. The purified air is cooled and then passes through the turbine expander (5) to obtain a gas phase flow and a liquid phase flow. The gas phase flow is pressurized by the oxygen-deficient air compressor (8) and cooled to obtain a liquid. The oxygen separation unit includes an oxygen-enriched liquid air storage tank (6), an oxygen-enriched liquid air pump (7), a lower distillation column (9), a main cooler (10), an upper distillation column (11), a subcooler (12), and a liquid oxygen pump (14). The liquid phase flows into the oxygen-enriched liquid air storage tank (6), is pressurized by the oxygen-enriched liquid air pump (7), and then enters the lower distillation column (9). The main cooler (10) serves as the condenser for the lower distillation column (9) and the reboiler for the upper distillation column (11), and is connected to both. The oxygen-enriched liquid air obtained from the lower distillation column (9) is then... After being subcooled by the subcooler (12), the gas enters the upper distillation column (11) for further distillation. Part of the low-pressure nitrogen obtained from the lower distillation column (9) is used as a heat source and enters the main cooler (10), while the other part is reheated to obtain low-pressure nitrogen. Part of the liquid nitrogen at the outlet of the main cooler (10) is used as reflux liquid, and the other part is subcooled by the cooler (12) and enters the top of the upper distillation column (11) as reflux liquid. The liquid oxygen obtained from the upper distillation column (11) is compressed by the liquid oxygen pump (14) and reheated to obtain high-pressure oxygen. The gasification power generation unit includes an oxygen-deficient liquid air storage tank (16), an oxygen-deficient liquid air pump (17), a superheater (18), and an expansion generator (19). The liquid obtained after cooling by the air liquefaction unit enters the oxygen-deficient liquid air storage tank (16), and is pressurized by the oxygen-deficient liquid air pump (17) and then vaporized to obtain oxygen-deficient air which enters the superheater (18). The superheated oxygen-deficient air then enters the expansion generator (19) to generate electricity. The cold exchange unit includes multiple cold storage / release devices (20) connected in series for cold storage and release; the air purification cooling and gas phase flow cooling in the air liquefaction unit, the oxygen and nitrogen reheating in the oxygen separation unit, and the oxygen-deficient liquid airization in the gasification power generation unit are all carried out in the cold exchange unit.

2. The integrated liquefied air energy storage oxygen production system of claim 1, wherein: The air liquefaction unit further includes a throttle valve (15) for throttling the cooled liquid into the oxygen-deficient liquid air storage tank (16); and / or, The oxygen separation unit also includes a nitrogen throttling valve (13). A portion of the liquid nitrogen from the outlet of the main cooler (10) is subcooled by the cooler (12) and then throttled by the nitrogen throttling valve (13) into the top of the distillation column (11) as its reflux liquid.

3. The integrated liquefied air energy storage oxygen production system of claim 1 or 2, wherein: The waste nitrogen gas at the top of the distillation column (11) is vented after the cold energy is recovered by the cold energy exchange unit.

4. The integrated liquefied air energy storage oxygen production system of claim 1, wherein: In the oxygen separation unit, the low-grade waste heat of the superheater (18) comes from the exhaust gas from coal chemical industry and the heat recovered after the compressor.

5. The integrated liquefied air energy storage oxygen production system of claim 1, wherein: When cold storage is implemented, the cold storage / release device (20) is a cold storage device, which includes a multi-stage cold storage bed with a cold storage medium for the cold fluid to enter. When the cold energy is stored in the first stage cold storage bed and reaches the maximum cold storage capacity, the cold fluid circulates between the stages of the cold storage bed to carry out the cold storage cycle.

6. The liquefied air energy storage and oxygen generation integrated system according to claim 1 or 5, characterized in that: When cooling is performed, the cooling storage / cooling release device (20) is a cooler, including a multi-stage cooling bed with a cooling storage medium for the entry of hot fluid. When heat is released in the first stage cooling bed to reach the maximum cooling capacity, the hot fluid circulates between the cooling beds to perform a cooling cycle.

7. A method for integrating liquefied air energy storage and oxygen production, employing the system described in any one of claims 1-6, characterized in that: The steps include the following: The raw air enters the air liquefaction unit, where it is filtered by the filter (1) to remove impurities. After being compressed by the booster (2), it enters the molecular sieve (3) to adsorb carbon dioxide, hydrocarbons and moisture in the air. The adsorbed air is pressurized by the main compressor (4), cooled by the cold exchange unit, expanded and cooled by the turbine expander (5), and the resulting gas-liquid two-phase flow enters the oxygen-enriched liquid air storage tank (6). The liquid phase oxygen-enriched liquid air is stored in the oxygen-enriched liquid air storage tank (6), and the gas phase oxygen-deficient liquid air is further pressurized by the oxygen-deficient air compressor (8) and cooled to liquid by the cold exchange unit. The liquid phase in the oxygen-enriched liquid air storage tank (6) is pressurized by the oxygen-enriched liquid air pump (7) and enters the lower distillation column (9). The rising gas in the lower distillation column (9) comes into contact with the reflux liquid nitrogen provided by the main cooler (10), increasing the nitrogen content. Another part of the liquid nitrogen in the main cooler (10) is sent to the upper distillation column (11) as reflux liquid after heat exchange in the subcooler (12). The oxygen-enriched liquid air obtained from the lower distillation column (9) is subcooled by the cooler (12) and then enters the upper distillation column (11) for further distillation. The liquid oxygen obtained from the upper distillation column (11) is compressed by the liquid oxygen pump (14) and reheated by the cold exchange unit to obtain high-pressure oxygen. Part of the low-pressure nitrogen obtained from the lower distillation column (9) is used as a heat source and enters the main cooler (10), while the other part is reheated by the cold exchange unit to obtain low-pressure nitrogen. The liquid obtained after cooling by the air liquefaction unit enters the oxygen-deficient liquid air storage tank (16), and after being pressurized by the oxygen-deficient liquid air pump (17), it is vaporized by the cold exchange unit to obtain oxygen-deficient air which enters the superheater (18). The superheated oxygen-deficient air enters the expansion generator (19) to generate electricity. The low-grade waste heat of the superheater (18) comes from the exhaust gas emitted by the coal chemical industry and the heat recovered after the compressor.

8. The integrated method for liquefied air energy storage and oxygen generation according to claim 7, characterized in that: The liquid obtained after cooling in the air liquefaction unit is throttled into the oxygen-deficient liquid air storage tank (16) through the throttle valve (15); and / or, a portion of the liquid nitrogen in the main cooler (10) is cooled by the cooler (12) and throttled into the top of the distillation column (11) by the nitrogen throttle valve (13) as its reflux liquid.

9. The integrated method for liquefied air energy storage and oxygen generation according to claim 7, characterized in that: The waste nitrogen gas at the top of the distillation column (11) is vented after the cold energy is recovered by the cold energy exchange unit.

10. The integrated method for liquefied air energy storage and oxygen generation according to claim 7, characterized in that: In the air liquefaction unit, the air separation is compressed, cooled, expanded and liquefied, and coarsely separated into oxygen-rich liquid air and oxygen-deficient air. The oxygen-deficient air is further compressed and cooled to obtain oxygen-deficient liquid air.

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