Sequestration pipeline-based compressed air energy storage system and compressed air energy storage method

Abstract

The application belongs to the technical field of compressed air energy storage, and discloses a compressed air energy storage system and method based on a sealed pipeline. The compressed air energy storage system based on the sealed pipeline comprises a compression subsystem, a recovery subsystem, a gas storage subsystem and an energy release subsystem. The compression subsystem comprises a compressor and a cooler; the recovery subsystem comprises a low-temperature water storage tank and a high-temperature water storage tank, the water outlet of the low-temperature water storage tank is communicated with the water inlet of the cooler, and the water outlet of the cooler is communicated with the water inlet of the high-temperature water storage tank; the gas storage subsystem comprises a sealed natural gas pipeline; the energy release subsystem comprises a reheater and an expander, the water inlet and the water outlet of the reheater are respectively communicated with the water outlet of the high-temperature water storage tank and the water inlet of the low-temperature water storage tank, and the gas inlet and the gas outlet of the reheater are respectively communicated with the sealed natural gas pipeline and the expander. The compressed air energy storage system based on the sealed pipeline has low cost, high safety, is suitable for different application scenarios, and has high energy recovery and utilization rate.

Description

Technical Field

[0001] This invention relates to the field of compressed air energy storage technology, and in particular to a compressed air energy storage system and method based on sealed pipelines. Background Technology

[0002] Compressed air energy storage systems are one of the core technologies for achieving large-scale electrical energy storage and solving the problem of renewable energy consumption. Their core lies in realizing the mutual conversion of electrical energy with pressure energy and thermal energy. Among these, the air storage device is a crucial component of the compressed air energy storage system, and its safety and operational stability directly affect the reliable operation of the system.

[0003] Existing compressed air energy storage systems, especially in large-scale applications, largely rely on underground gas storage spaces such as salt caverns. However, in engineering practice, they generally face challenges such as limited site selection, long construction periods, and high upfront investment, hindering their widespread application in non-salt cavern areas and distributed scenarios. Furthermore, in existing technologies, the heat storage medium often uses heat transfer oil or molten salt, which are costly and pose leakage risks.

[0004] Therefore, there is an urgent need to propose a compressed air energy storage system and method based on sealed pipelines to solve the above problems. Summary of the Invention

[0005] The first objective of this invention is to provide a compressed air energy storage system based on sealed pipelines, which can utilize sealed natural gas pipelines as energy storage carriers, has low cost, high safety, and is adaptable to different application scenarios; and has a high energy recovery and utilization rate.

[0006] To achieve this objective, the present invention adopts the following technical solution: Compressed air energy storage systems based on sealed pipelines include: A compression subsystem, comprising a compressor and a cooler, wherein the air inlet of the cooler is connected to the air outlet of the compressor; A recycling subsystem includes a low-temperature water storage tank and a high-temperature water storage tank. The outlet of the low-temperature water storage tank is connected to the inlet of the cooler, and the outlet of the cooler is connected to the inlet of the high-temperature water storage tank. A gas storage subsystem, the gas storage subsystem including a sealed natural gas pipeline, the inlet of the sealed natural gas pipeline being connected to the outlet of the cooler; The energy release subsystem includes a reheater and an expander. The inlet of the reheater is connected to the outlet of the high-temperature water storage tank, the outlet of the reheater is connected to the inlet of the low-temperature water storage tank, the air inlet of the reheater is connected to the air outlet of the sealed natural gas pipeline, and the air outlet of the reheater is connected to the air inlet of the expander.

[0007] As an optional technical solution for a compressed air energy storage system based on a sealed pipeline, the compressed air energy storage system based on a sealed pipeline includes multiple stages of compressors and multiple stages of coolers. The multiple stages of compressors and multiple stages of coolers are arranged alternately in sequence. The air inlet of the cooler located between two stages of compressors is connected to the air outlet of the upper stage compressor of the two stages, and the air outlet of the cooler is connected to the air inlet of the lower stage compressor of the two stages. The air outlet of the last stage cooler is connected to the air inlet of the sealed natural gas pipeline. The water inlets of the multiple stages of coolers are respectively connected to the water outlet of the low-temperature water storage tank, and the water outlets of the multiple stages of coolers are respectively connected to the water inlet of the high-temperature water storage tank.

[0008] As an optional technical solution for a compressed air energy storage system based on sealed pipelines, the compressed air energy storage system based on sealed pipelines includes multiple stages of reheaters and multiple stages of expanders. The multiple stages of reheaters and expanders are arranged alternately in sequence. The air inlet of the expander located between two stages of reheaters is connected to the air outlet of the upper stage of the two stages of reheaters, and the air outlet of the expander is connected to the air inlet of the lower stage of the two stages of reheaters. The air outlet of the last stage of expander is connected to the outside. The water inlets of the multiple stages of reheaters are respectively connected to the water outlet of the high-temperature water storage tank, and the water outlets of the multiple stages of reheaters are respectively connected to the water inlet of the low-temperature water storage tank.

[0009] As an optional technical solution for a compressed air energy storage system based on a sealed pipeline, the compressed air energy storage system based on a sealed pipeline further includes a first water pump, which is located between the outlet of the low-temperature water storage tank and the inlet of the cooler.

[0010] As an optional technical solution for a compressed air energy storage system based on a sealed pipeline, the compressed air energy storage system based on a sealed pipeline further includes a second water pump, which is located between the outlet of the high-temperature water storage tank and the inlet of the reheater.

[0011] As an optional technical solution for a compressed air energy storage system based on a sealed pipeline, the compressed air energy storage system based on a sealed pipeline further includes a dehumidification device, which is located between the outlet of the cooler and the inlet of the sealed natural gas pipeline.

[0012] As an optional technical solution for a compressed air energy storage system based on sealed pipelines, a regulating valve is provided between the cooler and the dehumidification device.

[0013] As an optional technical solution for a compressed air energy storage system based on a sealed pipeline, the energy release subsystem also includes a generator connected to the expander, and the expander is capable of performing work to drive the generator to generate electricity.

[0014] The second objective of this invention is to provide a compressed air energy storage method that utilizes sealed natural gas pipelines as the energy storage carrier, which is low in cost, high in safety, adaptable to different application scenarios, and has a high energy recovery and utilization rate.

[0015] To achieve this objective, the present invention adopts the following technical solution: The compressed air energy storage method employs the aforementioned compressed air energy storage system based on a sealed pipeline. This system, during operation, has both an energy storage state and an energy release state, wherein: In the energy storage state, ambient air is compressed by the compressor and cooled by the cooler in sequence before flowing into and being stored in the sealed natural gas pipeline. At the same time, low-temperature water enters the cooler through the low-temperature water storage tank and exchanges heat with the high-pressure air formed by compression to form high-temperature water which then flows into the high-temperature water storage tank. In the energy release state, the high-pressure air is released from the sealed natural gas pipeline and enters the reheater where it is heated by the high-temperature water entering from the high-temperature water storage tank. The heated high-pressure air then enters the expander and expands to do work. At the same time, the low-temperature water flowing out of the reheater flows back to the low-temperature water storage tank, completing the cycle.

[0016] As an optional technical solution for compressed air energy storage, the sealed natural gas pipeline needs to undergo internal testing, pressure resistance testing, and sealing evaluation before use.

[0017] The beneficial effects of this invention are: The compressed air energy storage system based on a sealed pipeline provided by this invention includes a compression subsystem, a recovery subsystem, a gas storage subsystem, and an energy release subsystem. The compression subsystem includes a compressor and a cooler; the recovery subsystem includes a cryogenic water storage tank and a high-temperature water storage tank; the energy release subsystem includes a reheater and an expander; and the gas storage subsystem includes a sealed natural gas pipeline. The compressor is used to compress ambient air. The cooler can cool the high-pressure air formed after compression, facilitating high-pressure air storage and reducing energy consumption and cost. Simultaneously, the high-temperature water formed by heat exchange in the cooler enters the high-temperature water storage tank for storage, realizing the recovery and utilization of compression energy. The reheater can reheat the compressed air released from the sealed natural gas pipeline to improve the efficiency of subsequent expansion; simultaneously, the cryogenic water formed by heat exchange in the reheater can enter the cryogenic water storage tank for storage, further realizing the recovery and utilization of energy.

[0018] Secondly, this compressed air energy storage system based on sealed pipelines uses water as the heat storage medium. Through the direct connection between the low-temperature water storage tank, the high-temperature water storage tank and the cooler, the water medium can be directly circulated from "low-temperature water inlet - heat absorption and heating - high-temperature water outlet - heat release and cooling - recirculation and reuse". The water medium is inexpensive and safe, and the circulation process does not require transfer, which further improves the heat utilization efficiency.

[0019] Furthermore, using sealed natural gas pipelines as energy storage carriers can revitalize existing infrastructure, avoid resource idleness, and improve pipeline asset utilization. Moreover, sealed natural gas pipelines have a complete structure, strong pressure resistance, meet the storage requirements of high-pressure air, and are highly safe. At the same time, sealed natural gas pipelines are not limited by terrain and can be adapted to different application scenarios. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of a compressed air energy storage system based on a sealed pipeline provided in an embodiment of the present invention.

[0021] In the picture: 1. Electric motor; 2. Compressor; 3. Cooler; 4. Low-temperature water storage tank; 5. First water pump; 6. Sealed natural gas pipeline; 7. Reheater; 8. Expander; 9. High-temperature water storage tank; 10. Second water pump; 11. Dehumidifier; 12. Regulating valve; 13. Generator. Detailed Implementation

[0022] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, the accompanying drawings show only the parts relevant to the present invention, and not all of the structures.

[0023] In the description of this invention, unless otherwise explicitly specified and limited, the terms "connected," "linked," and "fixed" 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 or an electrical 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 based on the specific circumstances.

[0024] 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 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 directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0025] In the description of this embodiment, the terms "upper," "lower," "right," etc., refer to the orientation or positional relationship shown in the accompanying drawings. They are used only for ease of description and simplification of operation, 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 present invention. In addition, the terms "first" and "second" are used only for distinction in description and have no special meaning.

[0026] This embodiment provides a compressed air energy storage system based on sealed pipelines. This compressed air energy storage system can use sealed natural gas pipelines as energy storage carriers, which is low in cost, high in safety, and adaptable to different application scenarios; and has a high energy recovery and utilization rate.

[0027] Specifically, such as Figure 1As shown, the compressed air energy storage system based on a sealed pipeline includes a compression subsystem, a recovery subsystem, a gas storage subsystem, and an energy release subsystem. The compression subsystem includes a compressor 2 and a cooler 3, with the inlet of the cooler 3 connected to the outlet of the compressor 2. The recovery subsystem includes a low-temperature water storage tank 4 and a high-temperature water storage tank 9, with the outlet of the low-temperature water storage tank 4 connected to the inlet of the cooler 3 and the outlet of the cooler 3 connected to the inlet of the high-temperature water storage tank 9. The gas storage subsystem includes a sealed natural gas pipeline 6, with the inlet of the sealed natural gas pipeline 6 connected to the outlet of the cooler 3. The energy release subsystem includes a reheater 7 and an expander 8, with the inlet of the reheater 7 connected to the outlet of the high-temperature water storage tank 9, the outlet of the reheater 7 connected to the inlet of the low-temperature water storage tank 4, the inlet of the reheater 7 connected to the outlet of the sealed natural gas pipeline 6, and the outlet of the reheater 7 connected to the inlet of the expander 8.

[0028] In actual operation, during energy storage, ambient air is first compressed by compressor 2 to form high-pressure air, which is actually high-temperature high-pressure air. The high-temperature high-pressure air is then cooled by cooler 3 to form low-temperature high-pressure air. The low-temperature high-pressure air flows into and is stored in the sealed natural gas pipeline 6. At the same time, low-temperature water enters cooler 3 through low-temperature water tank 4 and exchanges heat with the high-temperature high-pressure air formed by compression to form high-temperature water. The high-temperature water flows into high-temperature water tank 9. During energy release, the low-temperature high-pressure air is released from sealed natural gas pipeline 6 and enters reheater 7. It is reheated by the high-temperature water entering from high-temperature water tank 9 to form high-temperature high-pressure air again. The reheated high-pressure air enters expander 8, where it expands and does work. At the same time, the low-temperature water formed after heat exchange flowing out of reheater 7 flows back to low-temperature water tank 4 for reuse, completing the cycle.

[0029] Based on the above design, compressor 2 is used to compress ambient air, and cooler 3 can cool the high-pressure air formed after compression, facilitating high-pressure air storage and reducing energy consumption and cost. Simultaneously, the high-temperature water generated by heat exchange in cooler 3 enters high-temperature water storage tank 9 for storage, realizing the recovery and utilization of compression energy. Reheater 7 can reheat the compressed air released from the sealed natural gas pipeline 6 to improve the efficiency of subsequent expansion and work. At the same time, the low-temperature water generated by heat exchange in reheater 7 can enter low-temperature water storage tank 4 for storage, further realizing energy recovery and utilization. Furthermore, this compressed air energy storage system based on sealed pipelines uses water as the heat storage medium. Through the direct connection between low-temperature water storage tank 4, high-temperature water storage tank 9, and cooler 3, a direct cycle of "low-temperature water inlet—heat absorption and heating—high-temperature water outlet—heat release and cooling—recirculation and reuse" is achieved. Water is inexpensive, highly safe, and the circulation process requires no intermediate transfer, further improving heat utilization efficiency. Furthermore, using the sealed natural gas pipeline 6 as an energy storage carrier can revitalize existing infrastructure, avoid resource idleness, and improve the utilization rate of pipeline assets. Moreover, the sealed natural gas pipeline 6 has a complete structure, strong pressure bearing capacity, meets the storage requirements of high-pressure air, and has high safety. At the same time, the sealed natural gas pipeline 6 is not limited by terrain and can be adapted to different application scenarios.

[0030] On the other hand, the cooler 3 in the compressed air energy storage system based on sealed pipelines plays a dual role of "cooling high-pressure air" and "heat exchange and storage", eliminating the need for a separate heat exchanger in the traditional recovery subsystem, simplifying the system structure, reducing equipment investment, lowering system construction and maintenance costs, and avoiding heat loss caused by additional heat exchangers, thereby improving heat recovery efficiency.

[0031] It should be noted that all six sealed natural gas pipelines are in-service pipelines that have completed design, construction, non-destructive testing, and hydrostatic testing. They possess the design pressure rating and structural integrity, thus meeting the basic requirements for serving as compressed air energy storage carriers and enabling long-distance power generation.

[0032] In this embodiment, the energy release subsystem also includes a generator 13, which is connected to an expander 8. The expander 8 can perform work to drive the generator 13 to generate electricity. The compression subsystem also includes a motor 1, which is electrically connected to a compressor 2. The motor 1 is used to drive the compressor 2 to operate. In the energy storage state, when the grid load is low or the renewable energy output is abundant, the system utilizes the surplus electrical energy, that is, the motor 1 drives the compressor 2 to compress the ambient air. The heat generated during the compression process is recovered through the recovery subsystem. The compressed high-pressure air is transported to the sealed natural gas pipeline 6 for storage through the connecting pipeline, thereby converting electrical energy into the pressure energy and internal energy of the gas. In the energy release state, the high-pressure air in the sealed natural gas pipeline 6 is released, heated by the reheater 7, and then enters the expander 8 to expand and perform work, driving the generator 13 to generate electricity, realizing the conversion of stored energy into electrical energy and outputting it to the grid.

[0033] Furthermore, the compressed air energy storage system based on the sealed pipeline includes a multi-stage compressor 2 and a multi-stage cooler 3. The multi-stage compressor 2 and the multi-stage cooler 3 are arranged alternately in sequence. The air inlet of the cooler 3 located between two stages of compressor 2 is connected to the air outlet of the upper stage compressor 2 in the two-stage compressor 2, and the air outlet of the cooler 3 is connected to the air inlet of the lower stage compressor 2 in the two-stage compressor 2. The air outlet of the last stage cooler 3 is connected to the air inlet of the sealed natural gas pipeline 6. Assuming that the compressor 2 and the cooler 3 are N stages each, and N≥2, then the air outlet of the first stage compressor 2, the first stage cooler 3, and the second stage compressor 3 are connected to the air outlet of the sealed natural gas pipeline 6. The air inlets of compressor 2, second-stage cooler 3, third-stage compressor 2, third-stage cooler 3... N-1 stage compressor 2, N-1 stage cooler 3, N-stage compressor 2 and N-stage cooler 3 are connected in sequence, and the air outlet of N-stage cooler 3 is connected to the air inlet of the sealed natural gas pipeline 6; the water inlet of multi-stage cooler 3 is connected to the water outlet of low-temperature water storage tank 4, and the water outlet of multi-stage cooler 3 is connected to the water inlet of high-temperature water storage tank 9. That is to say, multiple water medium channels in multi-stage cooler 3 are set in parallel, and the two ends of the parallel connection are connected to the water outlet of low-temperature water storage tank 4 and the water inlet of high-temperature water storage tank 9, respectively. The use of a multi-stage compressor 2 connected in series with an interstage cooler 3 can, on the one hand, reduce the temperature during the air compression process, reduce compression power consumption, and reduce energy loss in the energy storage state; on the other hand, it can control the final intake temperature of high-pressure air, avoid thermal damage to the sealed natural gas pipeline 6 and sealing structure caused by high-temperature air, and ensure the long-term safety and stability of the gas storage subsystem; at the same time, the interstage cooler 3 can recover the waste heat of compression and transport it to the high-temperature water storage tank 9 for storage, which can be used for subsequent expansion power generation heating, realizing efficient energy recycling.

[0034] Similarly, a compressed air energy storage system based on sealed pipelines includes a multi-stage reheater 7 and a multi-stage expander 8. The multi-stage reheater 7 and multi-stage expander 8 are arranged sequentially and alternately. The air inlet of the expander 8 located between two reheaters 7 is connected to the air outlet of the upper reheater 7 in the two-stage reheater 7, and the air outlet of the expander 8 is connected to the air inlet of the lower reheater 7 in the two-stage reheater 7. The air outlet of the last expander 8 is connected to the outside. Assuming that the reheater 7 and expander 8 are each M stages, and M≥2, then the first stage reheater 7, the first stage expander 8, the second stage reheater 7, the second stage expander 8, and the first stage expander 8 are arranged in a staggered manner. Expander 8, third-stage reheater 7, third-stage expander 8... M-1 stage reheater 7, M-1 stage expander 8, M-stage reheater 7 and M-stage expander 8 are connected in sequence, and the outlet of M-stage expander 8 is connected to the outside (here it is connected to generator 13); the inlet of multi-stage reheater 7 is connected to the outlet of high-temperature water storage tank 9, and the outlet of multi-stage reheater 7 is connected to the inlet of low-temperature water storage tank 4. That is to say, multiple water medium channels in multi-stage reheater 7 are set in parallel, and the two ends of the parallel connection are connected to the outlet of high-temperature water storage tank 9 and the inlet of low-temperature water storage tank 4, respectively. The system employs a multi-stage expander 8 and a multi-stage reheater 7. After high-pressure air is discharged from the sealed natural gas pipeline 6, it enters each stage of the expander 8 to perform work. A reheater 7 is installed between adjacent expanders 8, using high-temperature water in a high-temperature storage tank 9 to reheat the high-pressure air. This prevents the air from freezing due to excessively low temperature during expansion, thus preventing condensation damage to the expanders 8. It also increases the inlet temperature of each expander 8, enhancing its work capacity and improving power generation efficiency. Simultaneously, it achieves stepped pressure reduction and release of high-pressure air, reducing pressure differential impact, ensuring the safe operation of the sealed natural gas pipeline 6, and fully utilizing the heat in the system.

[0035] Furthermore, to ensure high consistency between system energy storage and release, M=N.

[0036] In this embodiment, both M and N are four stages. A four-stage compression and cooling system is adopted. The exhaust temperature of each stage compressor 2 does not exceed 151°C, the temperature of the cryogenic water storage tank 4 is 10°C-15°C, and the intake temperature of each stage compressor 2 is 20°C under a design heat exchange differential of 5°C. The exhaust pressure of the final stage compressor 2 does not exceed 8MPa, and after pressure loss through pipe sections and components, it is stored at 7.5MPa in the sealed natural gas pipeline 6. The reheater 7 reheats the high-pressure air to the design temperature, which is determined based on the exhaust temperature of compressor 2, and here the maximum is 140.37°C.

[0037] Optionally, the compressed air energy storage system based on the sealed pipeline also includes a first water pump 5 and a second water pump 10. The first water pump 5 is located between the outlet of the low-temperature water storage tank 4 and the inlet of the cooler 3; the second water pump 10 is located between the outlet of the high-temperature water storage tank 9 and the inlet of the reheater 7. The arrangement of the first water pump 5 and the second water pump 10 can increase the circulation of low-temperature water and high-temperature water, respectively.

[0038] In this embodiment, the outlet of the first water pump 5 is connected to the multi-stage cooler 3; the outlet of the second water pump 10 is connected to the inlet of the multi-stage reheater 7.

[0039] Optionally, the compressed air energy storage system based on the sealed pipeline also includes a dehumidification device 11, which is located between the outlet of the cooler 3 and the inlet of the sealed natural gas pipeline 6. In this embodiment, the dehumidification device 11 is located between the last stage cooler 3 (i.e., the Nth stage cooler 3) and the inlet of the sealed natural gas pipeline 6. The dehumidification device 11 can remove water vapor from the high-pressure air, which on the one hand prevents liquid water from entering the sealed natural gas pipeline 6, preventing corrosion and rust of the pipeline and sealing structure, and ensuring the sealing performance of the sealed natural gas pipeline 6; on the other hand, it can prevent condensation and ice formation of high-pressure air in the sealed natural gas pipeline 6 and during the expansion power generation process, and prevent liquid hammer damage to the expander 8; at the same time, it reduces scaling in the sealed natural gas pipeline 6, improving the system's heat exchange efficiency and operational stability.

[0040] Furthermore, a regulating valve 12 is provided between the cooler 3 and the dehumidification device 11 to regulate the speed of the high-pressure air entering the dehumidification device 11, so as to avoid the flow rate being too fast and the dehumidification being incomplete.

[0041] It should be noted that by changing the state of the high-pressure air through the cooler 3 and the dehumidifier 11, the dew point temperature of the high-pressure air entering the sealed natural gas pipeline 6 is controlled within a preset range, for example, the pressure dew point of the high-pressure air is not higher than -40℃, so as to reduce the risk of corrosion of the inner wall of the pipeline.

[0042] This embodiment also provides a compressed air energy storage method that uses sealed natural gas pipelines as energy storage carriers. This method is low in cost, high in safety, and adaptable to different application scenarios; moreover, it has a high energy recovery and utilization rate.

[0043] Specifically, the compressed air energy storage method employs the aforementioned compressed air energy storage system based on sealed pipelines. This system operates in both an energy storage state and an energy release state, wherein: In the energy storage state, ambient air is compressed by compressor 2 and cooled by cooler 3 before flowing into and being stored in sealed natural gas pipeline 6. At the same time, low-temperature water enters cooler 3 through low-temperature water tank 4 and exchanges heat with the high-pressure air formed by compression to form high-temperature water which flows into high-temperature water tank 9. In the energy release state, high-pressure air is released from sealed natural gas pipeline 6 and enters reheater 7 where it is heated by high-temperature water entering from high-temperature water tank 9. The heated high-pressure air enters expander 8 and expands to do work. At the same time, low-temperature water flowing out of reheater 7 flows back into low-temperature water tank 4, and the cycle is completed.

[0044] Preferably, in the energy storage state, the motor 1 drives the compressors 2 at each stage to operate. The ambient air is compressed by the first stage compressor 2 to high-temperature and high-pressure air and enters the first stage cooler 3. At the same time, low-temperature water is pumped from the low-temperature water storage tank 4 to the first stage cooler 3 by the first water pump 5 to cool the high-pressure air in the first stage cooler 3. The cooled high-pressure air enters the second stage compressor 2 and the second stage cooler 3. At the same time, low-temperature water is pumped from the low-temperature water storage tank 4 to the second stage cooler 3 by the first water pump 5 to cool the high-pressure air a second time in the second stage cooler 3. ... After the high-pressure air undergoes multiple stages of compression and interstage cooling, the high-pressure air flowing out of the last stage cooler 3 first enters the dehumidification device 11 for drying, and then flows into and is stored in the sealed natural gas pipeline 6. At the same time, the high-temperature water that has absorbed the heat of compression flows out from each stage cooler 3 to the high-temperature water storage tank 9.

[0045] In the energy release state, high-pressure air is released from the sealed natural gas pipeline 6, heated by high-temperature water from the high-temperature water storage tank 9 pumped by the second water pump 10 in the first-stage reheater 7, and then enters the first-stage expander 8 to expand and do work; the exhaust gas from the first-stage expander 8 enters the second-stage reheater 7 and is heated by high-temperature water from the high-temperature water storage tank 9, and then enters the second-stage expander 8 to expand and do work, ...; after multiple stages of heating and expansion, the high-pressure air is discharged into the environment, while the low-temperature water flowing out of each stage of the reheater 7 flows back into the low-temperature water storage tank, and the system completes one cycle.

[0046] In this embodiment, the energy storage / release capacity is designed to be 100MW, the system can generate electricity for 6.00 hours, and the system's electricity-to-electricity conversion efficiency is 65.14%.

[0047] It should be noted that, considering that the sealed natural gas pipeline 6 has been idle for a long time, it may suffer from problems such as internal wall corrosion, coating aging and reduced sealing performance due to residual moisture, air or impurities in the pipeline. Before use, the sealed natural gas pipeline 6 needs to undergo special assessments such as internal inspection, pressure test and sealing performance evaluation to confirm that it can withstand the periodic filling and discharging of compressed air.

[0048] Specifically, internal testing involves using ultrasonic testing or magnetic flux leakage testing to inspect the pipe wall thickness and geometric deformation. For example, a pipe is considered usable if it has no localized corrosion or mechanical damage exceeding 10% of the design wall thickness and the ellipticity deformation does not exceed 3% of the nominal diameter. The pressure test uses a hydrostatic pressure test at 1.25 to 1.5 times the design pressure, with a pressure stabilization time of at least 30 minutes. The criterion is that the pressure drop during the test is no more than 1%, and there is no leakage or visible plastic deformation in the pipe wall. After passing the pressure test, a sealing assessment is performed using dry compressed air, i.e., continuous pressure holding for 24 hours at 1.1 times the maximum working pressure, with a pressure drop rate not exceeding 1% within 24 hours of pressure stabilization. A leak detection solution (such as soapy water) is applied to the welds and joints, and the criterion is that no bubbles are generated.

[0049] Furthermore, after confirming that it meets the requirements for compressed air energy storage, the sealed natural gas pipeline 6 is dried to remove any residual moisture inside the pipeline, and an inlet and outlet port are installed at both ends respectively.

[0050] 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 will be able to make various obvious changes, readjustments, and substitutions without departing from the scope of protection of the present invention. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A compressed air energy storage system based on a sealed pipeline, characterized in that, include: A compression subsystem, comprising a compressor (2) and a cooler (3), wherein the air inlet of the cooler (3) is connected to the air outlet of the compressor (2); The recycling subsystem includes a low-temperature water storage tank (4) and a high-temperature water storage tank (9). The outlet of the low-temperature water storage tank (4) is connected to the inlet of the cooler (3), and the outlet of the cooler (3) is connected to the inlet of the high-temperature water storage tank (9). A gas storage subsystem, the gas storage subsystem including a sealed natural gas pipeline (6), the inlet of the sealed natural gas pipeline (6) being connected to the outlet of the cooler (3); The energy release subsystem includes a reheater (7) and an expander (8). The inlet of the reheater (7) is connected to the outlet of the high-temperature water storage tank (9), the outlet of the reheater (7) is connected to the inlet of the low-temperature water storage tank (4), the air inlet of the reheater (7) is connected to the air outlet of the sealed natural gas pipeline (6), and the air outlet of the reheater (7) is connected to the air inlet of the expander (8).

2. The compressed air energy storage system based on a sealed pipeline according to claim 1, characterized in that, The compressed air energy storage system based on the sealed pipeline includes a multi-stage compressor (2) and a multi-stage cooler (3). The multi-stage compressor (2) and the multi-stage cooler (3) are arranged alternately in sequence. The air inlet of the cooler (3) located between two stages of the compressor (2) is connected to the air outlet of the upper stage compressor (2) of the two stages of the compressor (2), and the air outlet of the cooler (3) is connected to the air inlet of the lower stage compressor (2) of the two stages of the compressor (2). The air outlet of the last stage cooler (3) is connected to the air inlet of the sealed natural gas pipeline (6). The water inlets of the multi-stage coolers (3) are respectively connected to the water outlet of the low-temperature water storage tank (4), and the water outlets of the multi-stage coolers (3) are respectively connected to the water inlet of the high-temperature water storage tank (9).

3. The compressed air energy storage system based on a sealed pipeline according to claim 1, characterized in that, The compressed air energy storage system based on sealed pipelines includes multiple reheaters (7) and multiple expanders (8). The multiple reheaters (7) and multiple expanders (8) are arranged alternately in sequence. The air inlet of the expander (8) located between two reheaters (7) is connected to the air outlet of the upper reheater (7) in the two reheaters (7). The air outlet of the expander (8) is connected to the air inlet of the lower reheater (7) in the two reheaters (7). The air outlet of the last expander (8) is connected to the outside. The water inlets of the multiple reheaters (7) are connected to the water outlet of the high-temperature water storage tank (9) respectively. The water outlets of the multiple reheaters (7) are connected to the water inlet of the low-temperature water storage tank (4) respectively.

4. The compressed air energy storage system based on a sealed pipeline according to any one of claims 1-3, characterized in that, The compressed air energy storage system based on sealed pipelines also includes a first water pump (5), which is located between the outlet of the low-temperature water storage tank (4) and the inlet of the cooler (3).

5. The compressed air energy storage system based on a sealed pipeline according to any one of claims 1-3, characterized in that, The compressed air energy storage system based on sealed pipelines also includes a second water pump (10), which is located between the outlet of the high-temperature water storage tank (9) and the inlet of the reheater (7).

6. The compressed air energy storage system based on a sealed pipeline according to any one of claims 1-3, characterized in that, The compressed air energy storage system based on the sealed pipeline also includes a dehumidification device (11), which is located between the outlet of the cooler (3) and the inlet of the sealed natural gas pipeline (6).

7. The compressed air energy storage system based on a sealed pipeline according to claim 6, characterized in that, A regulating valve (12) is provided between the cooler (3) and the dehumidification device (11).

8. The compressed air energy storage system based on a sealed pipeline according to claim 1, characterized in that, The energy release subsystem also includes a generator (13), which is connected to the expander (8). The expander (8) can perform work to drive the generator (13) to generate electricity.

9. A compressed air energy storage method, characterized in that, The compressed air energy storage system based on a sealed pipeline as described in any one of claims 1-8 is used for energy storage. The compressed air energy storage system based on a sealed pipeline has an energy storage state and an energy release state during operation, wherein: In the energy storage state, ambient air is compressed by the compressor (2) and cooled by the cooler (3) in sequence before flowing into and being stored in the sealed natural gas pipeline (6). At the same time, low-temperature water enters the cooler (3) through the low-temperature water storage tank (4) and exchanges heat with the high-pressure air formed by compression to form high-temperature water which then flows into the high-temperature water storage tank (9). In the energy release state, the high-pressure air is released from the sealed natural gas pipeline (6) and enters the reheater (7) where it is heated by the high-temperature water entering from the high-temperature water storage tank (9). The heated high-pressure air enters the expander (8) and expands to do work. At the same time, the low-temperature water flowing out of the reheater (7) flows back to the low-temperature water storage tank (4), and the cycle is completed.

10. The compressed air energy storage method according to claim 9, characterized in that, Before use, the sealed natural gas pipeline (6) needs to undergo internal testing, pressure testing and sealing evaluation.

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