LNG and compressed air underground combined storage system and method

Abstract

The invention relates to an LNG and compressed air underground combined storage system and method. The system comprises a plurality of LNG storage caverns, a plurality of compressed air storage caverns, a combined storage roadway, an LNG vertical shaft, a compressed air vertical shaft, an LNG inlet and outlet pipeline and a compressed air inlet and outlet pipeline, and the LNG storage caverns and the compressed air storage caverns are arranged on the two sides of the combined storage roadway. The LNG storage caverns and the compressed air storage caverns located on the same side of the combined storage roadway are alternately arranged along the combined storage roadway, and the LNG storage caverns and the compressed air storage caverns are distributed in the symmetrical positions of the two sides of the axis of the combined storage roadway respectively. The energy utilization rate is increased, surrounding rock damage is reduced, meanwhile, the space utilization rate is high, the construction period is short, and the construction difficulty is small.

Description

Technical Field

[0001] This invention belongs to the field of underground cryogenic storage technology, and relates to an underground combined storage system and method for LNG and compressed air. Background Technology

[0002] Underground LNG storage facilities are deep-earth engineering facilities that achieve large-scale natural gas storage based on the principle of cryogenic phase change. Their operation follows the Rankine-Linde cycle thermodynamic process: in the natural gas liquefaction stage, multi-stage refrigeration units compress the gaseous natural gas to form a supercritical fluid for storage; in the regasification and peak-shaving stage, the LNG is reheated, causing it to transform into atmospheric pressure gaseous natural gas and injected into the gas transmission network. This storage system achieves cross-seasonal regulation and emergency peak-shaving functions for natural gas through a phase change cycle of "gas phase → liquid phase → gas phase".

[0003] Compressed air energy storage (CASS) is a physical energy storage technology that uses air as the working medium to store and release electrical energy across time periods. Its operating mechanism follows the Brayton cycle principle: during periods of low grid load, surplus electricity drives a multi-stage compressor to pressurize ambient air and store it in underground salt caverns or artificial gas storage facilities; during periods of high grid load, high-pressure air is released through a control valve group, heated in a combustion chamber, and then drives a multi-stage turbine expander to power a generator set, completing the cyclic conversion of "electrical energy → compression potential energy → electrical energy". This technology achieves power decoupling between the generation and consumption sides through energy time shifting, effectively solving the problem of real-time power supply and demand imbalance in the power system and improving the grid's ability to absorb intermittent power sources such as wind and solar power.

[0004] When compressed air is stored underground on its own, a significant amount of additional energy is required for heat recovery. If the large amount of heat generated during compression is not effectively recovered, it will lead to a significant decrease in system efficiency. At the same time, this heat can damage the surrounding rock of the compressed air storage tank, affecting its stability.

[0005] A standalone underground LNG storage facility generates a large amount of cold energy during the storage and vaporization of LNG. If this cold energy is not utilized, it will cause the spread of the frozen zone around the LNG storage facility, affecting the stability of the surrounding rock. Summary of the Invention

[0006] (a) Technical problems to be solved

[0007] The technical problem this patent aims to solve is that existing underground compressed air energy storage systems generate a large amount of high-temperature gas during energy release, requiring additional cooling facilities and energy consumption for cooling. Meanwhile, low-temperature cold energy inevitably dissipates during underground LNG storage, requiring heating or recovery systems to balance it, resulting in low energy utilization and high operating costs. The patent seeks to efficiently couple these two processes within the same underground space, achieving direct neutralization of the heat released by compressed air and the cold energy of LNG, avoiding the investment and losses of independent energy regulation devices, and improving overall energy utilization efficiency and the economic efficiency and safety of the storage facility operation.

[0008] (II) Technical Solution

[0009] The first aspect of this invention proposes an underground combined storage system for LNG and compressed air. The system includes multiple LNG storage caverns, multiple compressed air storage caverns, a combined storage tunnel, an LNG shaft, a compressed air shaft, LNG inlet / outlet pipelines, and compressed air inlet / outlet pipelines. The LNG storage caverns and compressed air storage caverns are located on both sides of the combined storage tunnel. Multiple LNG storage caverns and multiple compressed air storage caverns located on the same side of the combined storage tunnel are alternately arranged along the combined storage tunnel. At symmetrical positions on both sides of the axis of the combined storage tunnel, LNG storage caverns and compressed air storage caverns are respectively arranged, such that adjacent positions of the LNG storage caverns are all compressed air storage caverns, and adjacent positions of the compressed air storage caverns are all LNG storage caverns.

[0010] According to a preferred embodiment of the present invention, the LNG inlet / outlet pipeline and the compressed air inlet / outlet pipeline each include a main pipe and multiple branch pipes. The multiple branch pipes of the LNG inlet / outlet pipeline are used to connect the multiple LNG storage chambers, and the multiple branch pipes of the compressed air inlet / outlet pipeline are used to connect the multiple compressed air storage chambers.

[0011] According to a preferred embodiment of the present invention, the main pipe of the LNG inlet / outlet pipeline connects its branch pipes to the LNG shaft, and the main pipe of the compressed air inlet / outlet pipeline connects its branch pipes to the compressed air shaft.

[0012] According to a preferred embodiment of the present invention, the LNG shaft and the compressed air shaft are located at opposite ends of the combined storage tunnel and extend toward the ground.

[0013] According to a preferred embodiment of the present invention, the plurality of LNG storage chambers are connected to the ground equipment of the LNG storage facility via the LNG inlet / outlet pipelines and the LNG shaft; the plurality of compressed air chambers are connected to the ground equipment of the compressed air storage facility via the compressed air inlet / outlet pipelines and the compressed air shaft.

[0014] According to a preferred embodiment of the present invention, the LNG storage cavern and the compressed air storage cavern are strip-shaped structures.

[0015] A second aspect of the present invention provides a method for underground joint storage of LNG and compressed air, comprising the following steps: arranging LNG storage caverns and compressed air storage caverns alternately, such that adjacent positions of LNG storage caverns are all compressed air storage caverns, and adjacent positions of compressed air storage caverns are all LNG storage caverns.

[0016] According to a preferred embodiment of the present invention, the method further includes: installing LNG storage caverns and compressed air storage caverns on both sides of the combined storage tunnel; arranging multiple LNG storage caverns and multiple compressed air storage caverns located on the same side of the combined storage tunnel alternately along the combined storage tunnel; and arranging LNG storage caverns and compressed air storage caverns at symmetrical positions on both sides of the axis of the combined storage tunnel.

[0017] According to a preferred embodiment of the present invention, the method further includes: installing LNG inlet / outlet pipelines and compressed air inlet / outlet pipelines in the LNG storage cavern, compressed air storage cavern, and combined storage tunnel, wherein the LNG inlet / outlet pipelines and compressed air inlet / outlet pipelines each include a main pipe and multiple branch pipes, the multiple branch pipes of the LNG inlet / outlet pipelines are used to connect the multiple LNG storage caverns, and the multiple branch pipes of the compressed air inlet / outlet pipelines are used to connect the multiple compressed air storage caverns.

[0018] According to a preferred embodiment of the present invention, the method further includes: connecting the main pipe of the LNG inlet / outlet pipeline to each of its branch pipes in the LNG shaft, and connecting the main pipe of the compressed air inlet / outlet pipeline to each of its branch pipes in the compressed air shaft, wherein the LNG shaft and the compressed air shaft are located at both ends of the combined storage tunnel and extend toward the ground.

[0019] According to a preferred embodiment of the present invention, the method further includes: connecting the plurality of LNG storage caverns to the ground equipment of the LNG storage facility through the LNG inlet / outlet pipelines and the LNG shaft; and connecting the plurality of compressed air caverns to the ground equipment of the compressed air storage facility through the compressed air inlet / outlet pipelines and the compressed air shaft.

[0020] (III) Beneficial Effects

[0021] The LNG compressed air underground combined storage system and storage method of the present invention utilize the cold source of the LNG storage tank and the heat source of compressed air, respectively, which improves the energy utilization rate and reduces the damage to the surrounding rock. At the same time, the combined storage has high space utilization, short construction period and low construction difficulty. Attached Figure Description

[0022] Figure 1 This is a plan view of an underground combined LNG and compressed air storage system according to an embodiment of the present invention.

[0023] Figure 2 This is a structural cross-sectional view of a portion of the LNG storage cavern and the compressed air storage cavern of an underground combined LNG and compressed air storage system according to an embodiment of the present invention.

[0024] Figure 3 This is a cross-sectional view of the LNG inlet and outlet pipeline structure of an underground combined LNG and compressed air storage system according to an embodiment of the present invention.

[0025] Figure 4 This is a cross-sectional view of the compressed air pipeline structure of an underground combined LNG and compressed air storage system according to an embodiment of the present invention.

[0026] Explanation of reference numerals in the attached figures:

[0027] 1 – LNG storage cavern; 2 – Compressed air storage cavern; 3 – LNG shaft; 4 – Compressed air shaft; 5 – Upper water collection well; 6 – Lower water collection well; 7 – Combined storage tunnel; 8 – LNG inlet / outlet pipeline; 9 – Compressed air inlet / outlet pipeline; 10 – Steel lining; 11 – Insulation layer; 12 – Lining; 13 – Sealing layer; 14 – Sliding layer; 15 – Reinforced concrete layer; 16 – Shotcrete layer; 17 – Rock layer; 18 – Steel structure layer; 19 – Pipeline insulation layer; 20 – Outer protective layer; 21 – Inner lining layer; 22 – Pressure bearing layer; 23 – Thermal insulation layer; 24 – Outer anti-corrosion layer. Detailed Implementation

[0028] To address the aforementioned technical problems, the LNG and compressed air underground combined storage system and method proposed in this invention alternately arranges underground LNG storage chambers and compressed air storage chambers, ensuring that adjacent positions of LNG storage chambers are all compressed air storage chambers, and vice versa. This allows for efficient coupling of the two within the same underground space, directly neutralizing the heat released by compressed air with the cold energy of LNG, avoiding the investment and losses of independent energy regulation devices, and improving overall energy utilization efficiency and the economic and safety aspects of storage operation.

[0029] As a preferred embodiment, the system also includes a joint storage tunnel, which serves as a shared tunnel for both systems. Pipelines or cables can be run through it, which also facilitates construction work.

[0030] A more preferable approach is to arrange the LNG storage caverns, compressed air storage caverns, and tunnels in a herringbone pattern or a "non-standard" shaped arrangement. This facilitates the systematic construction of the combined storage system. Specifically, the LNG storage caverns and compressed air storage caverns can be installed on both sides of the combined storage tunnel. Multiple LNG storage caverns and multiple compressed air storage caverns located on the same side of the combined storage tunnel can be alternately arranged along the tunnel. Furthermore, LNG storage caverns and compressed air storage caverns can be symmetrically positioned on both sides of the tunnel's axis. This approach is structurally simple and achieves the effect that adjacent positions of LNG storage caverns are all compressed air storage caverns, and adjacent positions of compressed air storage caverns are all LNG storage caverns.

[0031] The embodiments of the present invention are described in detail below. These embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0032] The following is for reference. Figure 1 and Figure 2 An underground combined storage system for LNG and compressed air according to an embodiment of the present invention is described.

[0033] like Figure 1 As shown, the underground combined LNG and compressed air storage system of this invention includes multiple LNG storage chambers 1, multiple compressed air storage chambers 2, LNG shafts 3, compressed air shafts 4, a first water collection well 5, a second water collection well 6, a combined storage tunnel 7, LNG inlet and outlet pipelines 8, compressed air inlet and outlet pipelines 9, and a filling body 10.

[0034] Multiple LNG storage chambers 1 and multiple compressed air storage chambers 2 are located underground and distributed on both sides of the combined storage tunnel 7. The combined storage tunnel 7 is also underground, parallel to the ground, and connects the multiple LNG storage chambers 1 and the compressed air storage chambers 2. Therefore, maintenance personnel can enter and exit the LNG storage chambers 1 and compressed air storage chambers 2 through the combined storage tunnel 7 for maintenance. Simultaneously, the combined storage tunnel 7 can also serve as a waste removal channel during excavation of the chambers.

[0035] In this embodiment, the axis of the combined storage tunnel 7 is a straight line, and the axes of each LNG storage chamber 1 and each compressed air storage chamber 2 intersect the axis of the combined storage tunnel 7 perpendicularly.

[0036] Furthermore, multiple LNG storage chambers 1 and multiple compressed air storage chambers 2, located on the same side of the combined storage tunnel 7, are arranged alternately along the combined storage tunnel 7. LNG storage chambers 1 and compressed air storage chambers 2 are symmetrically positioned on both sides of the axis of the combined storage tunnel 7. Therefore, adjacent positions of LNG storage chamber 1 are all adjacent to compressed air storage chamber 2, and adjacent positions of compressed air storage chamber 2 are all adjacent to LNG storage chamber 1.

[0037] LNG storage cavern 1 releases cold energy during LNG storage, and also releases a large amount of cold energy during the vaporization process when outputting natural gas. Compressed air storage cavern 2, during operation, is compressed and injected into the underground cavern by an externally powered compressor. This compression process generates a large amount of heat, causing the internal temperature to rise significantly, reaching over 200°C. By interleaving LNG storage cavern 1 and compressed air storage cavern 2, with LNG storage cavern 1 surrounded by compressed air storage cavern 2, this underground combined LNG and compressed air storage arrangement can control the distance between adjacent LNG storage cavern 1 and compressed air storage cavern 2 located on the same side of the combined storage tunnel 7, and simultaneously control the distance between LNG storage cavern 1 and compressed air storage cavern 2 located on the same horizontal row on both sides of the combined storage tunnel 7. This allows for the control of the scale of the freeze zone diffusion during LNG storage cavern 1's LNG storage process.

[0038] In this embodiment, the distance between the LNG storage chamber 1 and the compressed air storage chamber 2 located on the same side of the combined storage tunnel 7 is defined as the first distance a, and the distance between the LNG storage chamber 1 and the compressed air storage chamber 2 located at opposite positions on opposite sides of the combined storage tunnel 7 is defined as the second distance b. The first distance a and the second distance b can be optimally determined through simulation based on the size of the LNG storage chamber 1 and the compressed air storage chamber 2. The first distance a is typically between 10 and 20 meters, and the second distance b is typically between 15 and 30 meters.

[0039] Setting up a separate underground compressed air storage facility incurs additional costs to neutralize the large amount of heat generated during operation. However, by using this combined underground LNG and compressed air storage arrangement, the cold energy dissipated during the storage and release of LNG in the LNG storage chamber 1 can neutralize the heat generated during the operation of the compressed air storage facility, reducing additional energy consumption and lowering the operating costs of the compressed air storage facility.

[0040] In this embodiment, the LNG storage cavern 1 and the compressed air storage cavern 2 are both strip-shaped structures, as is the combined storage tunnel 7. Neither the LNG storage cavern 1 nor the compressed air storage cavern 2 intersects with each other, and neither makes any turns. The LNG storage cavern 1 and the compressed air storage cavern 2 have simple structures and are easy to construct.

[0041] In this embodiment, the burial depth and cross-sectional area of ​​the LNG storage cavern 1 and the compressed air storage cavern 2 can be comprehensively determined based on the specific conditions of the construction site of the LNG and compressed air combined storage facility, including topography, geology, groundwater, surrounding rock parameters, in-situ stress, and storage pressure. Obviously, the better the integrity of the surrounding rock, the greater its strength, the lower the groundwater level, and the more uniform the in-situ stress, the shallower the burial depth and the larger the cross-sectional area of ​​the LNG storage cavern 1 and the compressed air storage cavern 2 can be.

[0042] In this embodiment, the number of LNG storage chamber 1 and compressed air storage chamber 2 can be determined based on the total volume of the LNG and compressed air combined storage facility and the construction period.

[0043] LNG shaft 3 is the connection point between the underground LNG storage cavern 1 and the ground surface; compressed air shaft 4 is the connection point between the underground compressed air storage 2 and the ground surface.

[0044] In this embodiment, the LNG inlet / outlet pipeline 8 and the compressed air inlet / outlet pipeline 9 each include a main pipe and multiple branch pipes. The multiple branch pipes of the LNG inlet / outlet pipeline 8 are used to connect multiple LNG storage chambers 1, and the multiple branch pipes of the compressed air inlet / outlet pipeline 9 are used to connect multiple compressed air storage chambers 2. The main pipe of the LNG inlet / outlet pipeline 8 connects its branch pipes to the LNG shaft 3, and the main pipe of the compressed air inlet / outlet pipeline 9 connects its branch pipes to the compressed air shaft 4. Preferably, both the LNG inlet / outlet pipeline 8 and the compressed air inlet / outlet pipeline 9 are arranged using the shortest path within the combined storage tunnel 7.

[0045] LNG shaft 3 and compressed air shaft 4 are located at both ends of the combined storage tunnel 7 and extend to the ground.

[0046] Multiple LNG storage chambers 1 are connected to the surface equipment of the underground LNG storage facility via LNG inlet / outlet pipelines 8 and LNG shafts 3. Multiple compressed air chambers 2 are connected to the surface equipment of the underground compressed air storage facility via compressed air inlet / outlet pipelines 9 and compressed air shafts 4.

[0047] LNG shaft 3 and compressed air shaft 4 are not sealed off, serving as connections between the combined LNG and compressed air storage facility and the surface. During construction, LNG shaft 3 and compressed air shaft 4 can be used as connecting channels to handle waste generated during tunnel excavation.

[0048] The first collection well 5 and the second collection well 6 are structures for collecting and managing groundwater. During the construction and maintenance of the underground joint storage facility, directional drainage can be carried out into the collection well 5 and the collection well 6.

[0049] like Figure 2 As shown, the LNG storage cavern 1 includes, from the inside out, a steel lining 10, an insulation layer 11, a lining 12, and a rock layer 17. The compressed air cavern 2 includes, from the inside out, a sealing layer 13, a sliding layer 14, a reinforced concrete layer 15, a shotcrete layer 16, and a rock layer 17. The lining 12 can be anchored to the rock layer 17 using shotcrete mesh as a support structure, and the shotcrete layer 16 is anchored to the rock layer 17.

[0050] The steel liner 10 is made of 304 grade or higher stainless steel plate and is used to seal the internal LNG.

[0051] The insulation layer 11 is tightly bonded to the steel lining 10 and the lining 13 to prevent water from entering the gaps between the layers and sublimating into ice, thereby reducing the insulation effect. The insulation layer 11 is used to insulate the LNG sealed inside the steel lining 2. Specifically, the insulation layer can generally be made of a certain thickness of rigid polyurethane or other insulation materials with good compressive strength.

[0052] Lining 12 is disposed between insulation layer 11 and rock layer 17, and together with rock layer 17, it bears the ground stress. When LNG is stored under high pressure, lining 12 can be used to bear part of the load and transfer the load to rock layer 17.

[0053] Sealing layer 13 is a flexible sealing layer made of steel plate or rubber, whose main function is to seal the gas and prevent compressed air leakage. It has high circumferential flexibility, can deform sufficiently, and can radially transmit air pressure to the lining and surrounding rock.

[0054] The sliding layer 14 is typically one or more of asphalt and polyurethane, used to balance the shear stress between the interface between the flexible sealing layer and the reinforced concrete lining layer during frequent inflation and deflation, and to reduce the friction between the flexible sealing layer and the reinforced concrete lining layer.

[0055] The reinforced concrete layer 15 is generally made of ordinary reinforced concrete, but special concrete such as high-ductility concrete may also be used. It is used to bear part of the load and transfer the load to the rock layer 17.

[0056] Upon completion of construction, the space between the combined storage tunnel 7 and the various facilities and equipment is filled with filler material 10.

[0057] In this embodiment of the invention, the LNG shaft 3 and the compressed air shaft 4 are located at the two ends of the combined storage tunnel 7, respectively. The purpose is to separate the surface equipment of the LNG underground storage connected to the LNG shaft 3 from the surface equipment of the compressed air underground storage connected to the compressed air shaft 4, so as to avoid insufficient ground space when they are concentrated together.

[0058] It should be noted that the cross-section of the combined storage tunnel 7 during excavation is a combination of a circular arch on top and a rectangle on the bottom, which is the same as the cross-section of the LNG storage cavern 1.

[0059] The cross-section of the lined compressed air storage cavern 2 is circular, which can ensure that the compressed air storage cavern 2 maintains a good stress state during operation.

[0060] In particular, during the long-term use of the reservoir, the rock layer 17 will develop fractured areas under long-term stratum stress. Due to the long-term influence of the surrounding rock on the stratum stress layer and excavation, as well as the frequent changes in ambient temperature, the strength and integrity of the rock layer 17 will gradually decrease. Therefore, before the reservoir is built, the fractured areas of the rock layer 17 need to be reinforced by grouting to maintain the strength and sealing of the surrounding rock.

[0061] Specifically, the LNG inlet / outlet pipeline 8 adopts a multi-layer insulation structure, including a steel structure layer 18, a pipeline insulation layer 19, and an outer protective layer 20. From the inside out, the pipeline consists of the steel structure layer 18, the insulation layer 19, and the outer protective layer 20. The steel structure layer 18 is made of steel; the pipeline insulation layer 19 uses polyurethane foam to preserve cold energy; and the outer protective layer 20 can be made of composite materials such as resin to mitigate external forces and enhance pipeline protection.

[0062] Specifically, the compressed air inlet and outlet pipeline 9 adopts a multi-layer composite structure, including an inner lining layer 21, a pressure-bearing layer 22, a heat insulation layer 23, and an outer anti-corrosion layer 24. From the inside out, the pipeline consists of the inner lining layer 21, the pressure-bearing layer 22, the heat insulation layer 23, and the outer anti-corrosion layer 24. The inner lining layer 21 can be made of a polymer coating to reduce internal wall friction resistance and minimize turbulence losses; the pressure-bearing layer 22 is made of high-strength steel, primarily used to withstand high pressure and alternating loads; the heat insulation layer 23 can be made of aerogel felt to reduce heat loss during inflation and maintain the air's ability to perform work; the outer anti-corrosion layer 24 can be made of epoxy coal tar coating to protect against corrosion from groundwater and other sources, and to resist physical wear during construction or operation.

[0063] In particular, the underground combined storage of LNG and compressed air of the present invention adopts direct coupling combined energy storage, which utilizes the large amount of cold energy emitted during the underground storage and release of LNG to neutralize the heat released during the operation of the underground compressed air storage. In this process, the rock layer 17 acts as a buffer layer for heat exchange.

[0064] In the description of this invention, "a plurality of" means two or more.

[0065] In the description of this invention, the specific material selection of the structure is only an example, and can be changed according to specific requirements during implementation.

[0066] In summary, this invention utilizes the cold energy dissipated from the LNG storage facility to neutralize the heat emitted during the operation of the compressed air underground storage facility, thereby reducing the energy consumption required for compressed air and controlling the freezing zone of the LNG storage facility. Simultaneously, it prevents heat sources from damaging the surrounding rock of the storage facility.

[0067] This invention relates to a combined storage system comprising multiple gas storage chambers, connecting tunnels, an LNG shaft, a compressed air shaft, a filling material, and inlet / outlet pipelines. The compressed air storage chambers are arranged in a cross-sectional configuration. Multiple chambers are positioned along the axial direction of the connecting tunnels, intersecting in that direction. Adjacent chambers and their opposite chambers on the connecting tunnels constitute different storage facilities. The LNG shaft and compressed air shaft extend towards the ground above the ends of the inlet / outlet pipelines. The compressed air storage facility is connected to the compressed air inlet / outlet pipelines, and the LNG storage facility is connected to the LNG inlet / outlet pipelines. The multiple storage chambers are connected to the underground compressed air storage facility and the surface equipment of the underground LNG storage facility via the inlet / outlet pipelines and shafts. The filling material fills the gaps between the multiple storage chambers, the inlet / outlet pipelines, and the connecting tunnels.

[0068] The underground combined storage system for LNG and compressed air utilizes the cold source of the LNG storage facility and the heat source of compressed air, which improves energy utilization and reduces damage to the surrounding rock. At the same time, the combined storage system has high space utilization, short construction period and low construction difficulty.

[0069] The above description is merely an embodiment of the present invention, intended to illustrate the purpose, technical solution, and method of the present invention, and is not intended to limit the patent scope of the present invention. Those skilled in the art can make improvements to the embodiments of the present invention based on the content disclosed in the application documents without departing from the technical concept and patent scope of the present invention.

Claims

1. An underground combined storage system for LNG and compressed air, characterized in that: The system includes multiple LNG storage caverns, multiple compressed air storage caverns, a combined storage tunnel, an LNG shaft, a compressed air shaft, LNG inlet and outlet pipelines, and compressed air inlet and outlet pipelines; The LNG storage cavern and the compressed air storage cavern are located on both sides of the combined storage tunnel; Multiple LNG storage chambers and multiple compressed air storage chambers located on the same side of the combined storage tunnel are arranged alternately along the combined storage tunnel. At symmetrical positions on both sides of the axis of the combined storage tunnel, LNG storage chambers and compressed air storage chambers are respectively arranged, so that the adjacent positions of the LNG storage chambers are all compressed air storage chambers, and the adjacent positions of the compressed air storage chambers are all LNG storage chambers.

2. The underground combined storage system for LNG and compressed air according to claim 1, characterized in that: The LNG inlet / outlet pipeline and the compressed air inlet / outlet pipeline each include a main pipe and multiple branch pipes. The multiple branch pipes of the LNG inlet / outlet pipeline are used to connect the multiple LNG storage chambers, and the multiple branch pipes of the compressed air inlet / outlet pipeline are used to connect the multiple compressed air storage chambers. The main pipe of the LNG inlet and outlet pipeline connects its branch pipes to the LNG shaft, and the main pipe of the compressed air inlet and outlet pipeline connects its branch pipes to the compressed air shaft.

3. The underground combined storage system for LNG and compressed air according to claim 2, characterized in that: The LNG shaft and compressed air shaft are located at opposite ends of the combined storage tunnel and extend towards the ground.

4. The underground combined storage system for LNG and compressed air according to claim 3, characterized in that: The multiple LNG storage caverns are connected to the surface equipment of the LNG storage facility through the LNG inlet and outlet pipelines and the LNG shaft; The plurality of compressed air chambers are connected to the ground equipment of the compressed air storage tank through the compressed air inlet and outlet pipes 9 and the compressed air shaft.

5. The underground combined storage system for LNG and compressed air according to any one of claims 1 to 4, characterized in that, The LNG storage cavern and the compressed air storage cavern are strip-shaped structures.

6. A method for underground combined storage of LNG and compressed air, characterized in that, Includes the following steps: The LNG storage caverns and compressed air storage caverns are arranged alternately, such that the adjacent positions of the LNG storage caverns are all compressed air storage caverns, and the adjacent positions of the compressed air storage caverns are all LNG storage caverns.

7. The underground combined storage method for LNG and compressed air according to claim 6, characterized in that, Also includes: The LNG storage cavern and the compressed air storage cavern are installed on both sides of the combined storage tunnel; Multiple LNG storage chambers and multiple compressed air storage chambers located on the same side of the joint storage tunnel are alternately arranged along the joint storage tunnel; At symmetrical locations on both sides of the axis of the combined storage tunnel, LNG storage caverns and compressed air storage caverns are respectively arranged.

8. The underground combined storage method for LNG and compressed air according to claim 7, characterized in that, Also includes: LNG inlet / outlet pipelines and compressed air inlet / outlet pipelines are installed in the LNG storage cavern, compressed air storage cavern, and combined storage tunnel. The LNG inlet / outlet pipeline and compressed air inlet / outlet pipeline each include a main pipe and multiple branch pipes. The multiple branch pipes of the LNG inlet / outlet pipeline are used to connect the multiple LNG storage caverns, and the multiple branch pipes of the compressed air inlet / outlet pipeline are used to connect the multiple compressed air storage caverns.

9. The underground combined storage method for LNG and compressed air according to claim 8, characterized in that, Also includes: The main pipe of the LNG inlet and outlet pipeline is connected to each of its branch pipes to the LNG shaft, and the main pipe of the compressed air inlet and outlet pipeline is connected to each of its branch pipes to the compressed air shaft. The LNG shaft and the compressed air shaft are located at both ends of the combined storage tunnel and extend to the ground.

10. The underground combined storage method for LNG and compressed air according to claim 9, characterized in that, Also includes: The multiple LNG storage caverns are connected to the surface equipment of the LNG storage facility through the LNG inlet and outlet pipelines and the LNG shaft; The plurality of compressed air chambers are connected to the ground equipment of the compressed air storage tank through the compressed air inlet and outlet pipes and the compressed air shaft.

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