Air reservoir system for compressed air energy storage power plants and method of construction thereof

Abstract

The application discloses a gas storage system, in particular to a gas storage system for compressed air energy storage power station and a construction method thereof, and belongs to the technical field of design and construction of energy storage power station gas storage building. The application provides a gas storage system for compressed air energy storage power station and a construction method thereof, which can significantly reduce the sealing requirement of equipment and the stress of the structure of the gas sealing layer. The gas storage system comprises a gas storage body and a constant temperature and pressure adjusting and maintaining mechanism, the inner cavity of the constant temperature and pressure adjusting and maintaining mechanism is connected with the inner cavity of the gas storage body, and the gas pressure and temperature stored in the gas storage body are always maintained within the specified pressure and temperature variation range under the regulation and control of the delivery and regulation medium of the constant temperature and pressure adjusting and maintaining mechanism. The construction method comprises the following steps: firstly, excavating the surrounding rock base reservoir, then grouting and reinforcing, constructing the waterproof layer, installing the water supplement pipe, the drainage pipe, the flower pipe and the corrugated steel lining layer, and finally pouring the flexible concrete lining layer and backfilling and grouting.

Description

Technical Field

[0001] This invention relates to a gas storage system, and more particularly to a gas storage system for a compressed air energy storage power station, belonging to the technical field of gas storage building design and construction for energy storage power stations. This invention also relates to a construction method for building the aforementioned gas storage system for a compressed air energy storage power station. Background Technology

[0002] Energy storage plays a crucial role in new power systems with new energy sources as the main body and a high proportion of renewable energy access. Its functions cover multiple dimensions, including energy regulation, system stability, and economic improvement. First, it balances the intermittency of new energy sources and improves the power system's absorption capacity. Second, it enhances the stability and reliability of the power grid. Third, it optimizes the economic efficiency and operational efficiency of the power system. Fourth, it supports technological innovation in new power systems.

[0003] Currently, various energy storage types have seen some development. Based on the energy conversion principle, mechanical energy storage, which has the characteristics of long-term energy storage, has developed rapidly due to its mature technology and high conversion efficiency, as well as its high energy density and low thermal storage cost. Pumped hydro storage and compressed air storage are particularly widely used in mechanical energy storage.

[0004] A compressed air energy storage power station mainly includes a compressor, expander, heat exchanger, hot and cold storage tanks, high-pressure air storage facility, pipeline system, gate valves, and pumps. The air storage facility is crucial to the success of the compressed air energy storage project and is also a key focus of investment control.

[0005] Compressed air energy storage facilities come in various layout types, such as large tank type, corridor type, annular tunnel type, and combinations thereof. To reduce storage costs and achieve high system efficiency, the storage facilities operate at high pressures. Due to the small diameter of air molecules, high requirements are placed on the sealing of the storage facilities. Sealing methods for storage facilities include steel-lined seals and polymer material seals.

[0006] Regardless of the layout and sealing method, most existing gas storage facilities operate in a constant-volume mode. This means that the volume of the storage facility remains constant during operation. When energy is released, the pressure decreases from P0 to P1, and the mass of the discharged gas is m = V(ρ0 - ρ1), where ρ0 is the gas density at the beginning of energy release and ρ1 is the gas density at the end of energy release. The density formula for an ideal gas is: ρ = PM / RT, where P is the absolute pressure; M is the molar mass of the gas (approximately 28.97 g / mol for air); R is the gas constant; and T is the absolute temperature (K). The gas temperature at time P0, i.e., the gas temperature T0, can be calculated using numerical analysis based on the storage facility's layout. During the exhaust process, the gas expands and absorbs heat, causing its temperature to decrease. The storage temperature T1 at the end of energy release can be obtained using the ideal gas law. Another disadvantage of constant-volume operation is the expansion and recompression of high-pressure gas in the gas storage tank, which consumes compression work and generates higher temperatures, posing greater technical challenges to the performance of the sealing materials and the structural design of the gas storage tank. Summary of the Invention

[0007] The technical problem to be solved by the present invention is to provide a gas storage system for compressed air energy storage power stations that can significantly reduce equipment sealing requirements and has a simple structure of gas sealing layer for stress, as well as a construction method for building the gas storage system for compressed air energy storage power stations.

[0008] The technical solution adopted to solve the above-mentioned technical problems is: a gas storage system for a compressed air energy storage power station, the gas storage system including a gas storage body and a constant temperature and pressure regulating and maintaining mechanism, the inner cavity of the constant temperature and pressure regulating and maintaining mechanism being connected to the inner cavity of the gas storage body, and the gas pressure and temperature of the gas stored in the gas storage body being maintained within a specified pressure and a specified temperature variation range under the regulation of the regulating medium delivered by the constant temperature and pressure regulating and maintaining mechanism.

[0009] Furthermore, the constant temperature and pressure regulating mechanism includes at least the upper reservoir of the pumped storage power station, the regulating medium is the regulating water stored in the upper reservoir, the upper reservoir is connected to the gas storage tank body through inlet and outlet water pipes, and the absolute pressure of the gas in the gas storage tank body is the sum of the elevation pressure difference between the water level of the upper reservoir and the water level of the gas storage tank and the atmospheric pressure.

[0010] The preferred embodiment of the above scheme is to also install a waterway maintenance valve, an inlet / outlet water control valve, and a gas storage tank maintenance drain valve on the inlet and outlet water pipes, respectively.

[0011] Furthermore, the gas storage unit itself includes at least an excavated surrounding rock foundation, a protective and solidifying structure, and an inner lining for the gas storage unit. The inner wall of the excavated surrounding rock foundation is constructed and reinforced by the protective and solidifying structure, which is then enclosed on the outer wall of the inner lining of the gas storage unit.

[0012] The preferred embodiment of the above scheme is that the protective solid structure includes at least a sprayed waterproof layer and a reinforced concrete lining layer, which are arranged sequentially from the inside to the outside on the inner wall of the excavated surrounding rock foundation. The gas storage tank inner tube is attached to the inner wall of the excavated surrounding rock foundation with the cooperation of the reinforced concrete lining layer.

[0013] Furthermore, the protective reinforcement structure also includes a wind-sprayed anchor layer, which is arranged between the sprayed waterproof layer and the inner wall of the excavated surrounding rock foundation, and sequentially reinforced between the reinforced concrete lining layer and the sprayed waterproof layer, and between the sprayed waterproof layer and the wind-sprayed anchor layer.

[0014] The preferred embodiment of the above scheme is that the gas storage tank body includes a sealing and leak-proof pressure equalization mechanism, the inner tube of the gas storage tank is made of a corrugated steel lining, the sealing and leak-proof pressure equalization mechanism is arranged on the outside of the corrugated steel lining, and the pressure inside and outside the corrugated steel lining is kept balanced by the pressure regulating medium output by the sealing and leak-proof pressure equalization mechanism.

[0015] Furthermore, the sealing and leak-proof pressure equalization mechanism includes multiple pressure-regulating pipes, one pressure equalization water supply pipe, and one pressure relief drain pipe. The vertically arranged pressure-regulating pipes are sequentially attached to the outer side of the corrugated steel lining in a circumferential direction. At least on the wall surface of each pressure-regulating pipe facing the corrugated steel lining, there are multiple pressure-regulating medium spray holes spaced apart from each other. One end of the pressure equalization water supply pipe is connected to the inlet and outlet water pipes, and the other end of the pressure equalization water supply pipe is connected to the input end of each pressure-regulating pipe. The input end of the pressure relief drain pipe is connected to the output end of each pressure-regulating pipe. At least the outer surface of each pressure-regulating pipe that is not in contact with the corrugated steel lining is attached to the corresponding reinforced concrete lining layer. The pressure inside and outside the corrugated steel lining is kept balanced by the pressure-regulating medium output from each pressure-regulating pipe.

[0016] The preferred method for the above scheme is to calculate the storage capacity of the gas storage facility using the following formula:

[0017] ;

[0018] P0=(Z 上死 -Z 库高 )ρg+P A .

[0019] Where: m is the total gas consumption, determined based on the expander's gas consumption per unit time and the number of hours of full-capacity operation; R is the gas constant, 8.314 J / (mol·K); T is the absolute temperature (K); M is the molar mass of the gas; P0 is the pressure at the initial moment of energy release (Pa); Z 上死 Z is the dead water level of the upper reservoir, in meters. 库高 ρ represents the low water level of the gas storage tank, in meters (m); ρ is the density of water, in kilograms per cubic meter of water. 3 g is the acceleration due to gravity; P A The local atmospheric pressure is expressed in Pa.

[0020] The regulating capacity V of the upper reservoir of a pumped storage power station -水库 =V -储气 ×K. Where K is the reservoir capacity margin coefficient, and the dead water level of the upper reservoir should meet the inlet and outlet water pipe flooding depth requirements.

[0021] The flow rate of the inlet and outlet water pipes is q=V -储气 / t, where t is the number of hours of full operation.

[0022] A construction method for building the gas storage system for the compressed air energy storage power station, wherein the gas storage system is constructed according to the following steps.

[0023] 1) Gas storage excavation and support: Excavation shall be carried out using the drill-and-blast method or the TBM method. During the construction period, steel mesh and shotcrete anchor support shall be installed according to the surrounding rock conditions, and a system of anchor bolts shall be set.

[0024] 2) Grouting of the excavated surrounding rock foundation shall be carried out by grouting without cover. During grouting, cracks shall be filled with grouting material. After grouting, the permeability shall meet the control standard of not more than 3Lu.

[0025] 3) Apply a waterproof layer to the shotcrete surface using a spraying method;

[0026] 4) Reinforcing steel fabrication and installation, installation of reinforcing steel mesh for concrete lining, laying of pressure-regulating water supply pipes, pressure-relieving drainage pipes and pressure-regulating perforated pipes, and burial of backfill grouting pipes;

[0027] 5) Corrugated steel lining installation: The corrugated steel lining can be installed in sections or pieces, and welded on site and inspected for compliance.

[0028] 6) Pour the flexible concrete lining layer, and backfill and grout after it reaches the grouting age.

[0029] The beneficial effects of this invention are as follows: The technical solution provided in this application introduces a constant temperature and pressure regulating mechanism into the gas storage tank body, and then connects the inner cavity of the constant temperature and pressure regulating mechanism to the inner cavity of the gas storage tank body. This ensures that the gas pressure and temperature stored within the gas storage tank body are always maintained within a specified pressure and temperature range under the regulation of the regulating medium delivered by the constant temperature and pressure regulating mechanism. This solves the technical problem in the prior art where the internal pressure and temperature of the gas storage tank repeatedly change due to energy storage and release, resulting in gradually increasing pressure and high sealing requirements during energy storage, and gradually decreasing pressure and significantly reduced sealing requirements during energy release, thus posing challenges to the performance of sealing materials and structural design of the gas storage tank. With the constant temperature and pressure regulating mechanism provided in this application, the pressure and temperature within the gas storage tank body are always maintained within a very small range of variation. Therefore, both the selection of sealing material performance and structural design can be unified, significantly reducing the equipment sealing requirements and simplifying the stress on the gas sealing layer structure, thus facilitating the selection of sealing material performance and the structural design of the gas storage tank. Attached Figure Description

[0030] Figure 1 This is a simplified structural diagram of the air storage system for a compressed air energy storage power station according to the present invention.

[0031] Figure 2 This is a horizontal sectional view of the gas storage tank body involved in the gas storage tank system for compressed air energy storage power stations according to the present invention.

[0032] The markings in the diagram are as follows: 1. Upper reservoir; 2. Inlet / outlet water pipe; 3. Waterway maintenance valve; 4. Inlet / outlet water control valve; 5. Gas storage maintenance and drainage valve; 6. Excavated surrounding rock foundation; 7. Gas storage inner tube; 8. Sprayed waterproof layer; 9. Reinforced concrete lining layer; 10. Mesh and sprayed anchor layer; 11. Pressure regulating pipe; 12. Pressure leveling and water supply pipe; 13. Pressure relief and drainage pipe. Detailed Implementation

[0033] like Figure 1 , Figure 2As shown, this invention provides a gas storage system for compressed air energy storage power stations that significantly reduces equipment sealing requirements, has a simple gas sealing layer structure, and is designed for stress control. It also includes a construction method for building the gas storage system. The gas storage system comprises a storage body and a constant temperature and pressure regulating mechanism. The inner cavity of the constant temperature and pressure regulating mechanism is connected to the inner cavity of the storage body. The pressure and temperature of the gas stored within the storage body are maintained within a specified pressure and temperature range under the regulation of the regulating medium supplied by the constant temperature and pressure regulating mechanism. This application provides a technical solution by introducing a constant temperature and pressure regulating mechanism into the storage body and connecting its inner cavity to the inner cavity of the storage body. This ensures that the pressure and temperature of the gas stored within the storage body are maintained within a specified pressure and temperature range under the regulation of the regulating medium supplied by the constant temperature and pressure regulating mechanism. This invention solves the technical challenges posed by the repeated changes in internal pressure and temperature during energy storage and release in existing gas storage systems. These changes lead to a gradual increase in pressure during energy storage, resulting in high sealing requirements, and a gradual decrease in pressure during energy release, significantly reducing sealing requirements. The constant temperature and pressure regulating mechanism provided in this application maintains the pressure and temperature within the gas storage system within a very small range. This allows for a unified approach to both the selection of sealing material performance and structural design, significantly reducing equipment sealing requirements and simplifying the stress on the gas sealing layer structure. This simplifies the selection of sealing material performance and the structural design of the gas storage system. Considering the existing technology and the location of the compressed air energy storage power station, the constant temperature and pressure regulating mechanism of this application includes at least an upper reservoir 1 of the pumped storage power station. The regulating medium is the regulating water stored in the upper reservoir. The upper reservoir is connected to the gas storage system via inlet and outlet pipes 2. The absolute pressure of the gas within the gas storage system is the sum of the elevation pressure difference between the water level in the upper reservoir and the water level in the gas storage system, and atmospheric pressure. In order to facilitate the control of gas pressure and temperature inside the gas storage tank, as well as the maintenance and repair of the equipment during subsequent use, this application also provides a waterway inspection valve 3, an inlet / outlet water control valve 4, and a gas storage tank maintenance drain valve 5 on the inlet / outlet water pipe 2.

[0034] Furthermore, considering the actual conditions of the construction site, the gas storage unit of this application includes at least an excavated surrounding rock foundation 6, a protective reinforcement structure, and a gas storage inner tube 7. The inner wall of the excavated surrounding rock foundation 6 is constructed and reinforced by the protective reinforcement structure, which is attached to the outer wall of the gas storage inner tube 7. In this case, the preferred structure is that the protective reinforcement structure includes at least a sprayed waterproof layer 8 and a reinforced concrete lining layer 9. The sprayed waterproof layer 8 and the reinforced concrete lining layer 9 are arranged sequentially from the inside to the outside on the inner wall of the excavated surrounding rock foundation 6, and the gas storage inner tube 7 is attached to the inner wall of the excavated surrounding rock foundation 6 in conjunction with the reinforced concrete lining layer 9. To improve the stability of the excavated surrounding rock foundation 6 during construction, the protective and solidification structure of this application also includes a wire mesh sprayed anchor layer 10. The wire mesh sprayed anchor layer 10 is arranged between the sprayed waterproof layer 8 and the inner wall of the excavated surrounding rock foundation 6, and is sequentially solidified between the reinforced concrete lining layer 9 and the sprayed waterproof layer 8, and between the sprayed waterproof layer 8 and the wire mesh sprayed anchor layer 10. Correspondingly, to eliminate the pressure difference between the inside and outside of the gas storage facility and reduce the sealing difficulty of the gas storage facility itself, the gas storage facility body of this application includes a sealing and leak-proof pressure equalization mechanism. The gas storage inner tube 7 is composed of a corrugated steel lining, and the sealing and leak-proof pressure equalization mechanism is arranged on the outside of the corrugated steel lining. The pressure inside and outside the corrugated steel lining is maintained in balance through the output pressure regulating medium of the sealing and leak-proof pressure equalization mechanism. More specifically, the sealing and leak-proof pressure equalization mechanism includes multiple pressure-regulating pipes 11, a pressure equalization water supply pipe 12, and a pressure relief drain pipe 13. The vertically arranged pressure-regulating pipes 11 are sequentially attached to the outside of the corrugated steel lining in a circumferential direction. At least on the wall surface of each pressure-regulating pipe 11 facing the corrugated steel lining, multiple pressure-regulating medium spray holes are arranged at intervals. One end of the pressure equalization water supply pipe 12 is connected to the inlet and outlet water pipes 2, and the other end of the pressure equalization water supply pipe 12 is connected to the input end of each pressure-regulating pipe 11. The input end of the pressure relief drain pipe 13 is connected to the output end of each pressure-regulating pipe 11. At least the outer surface of each pressure-regulating pipe 11 that is not in contact with the corrugated steel lining is attached to the corresponding reinforced concrete lining layer 9. The pressure inside and outside the corrugated steel lining is kept balanced by the pressure-regulating medium output from each pressure-regulating pipe.

[0035] Meanwhile, based on the scale of the compressed air energy storage power station to be constructed, the storage capacity of the gas storage unit in this application is calculated using the following formula.

[0036] ;

[0037] P0=(Z 上死 -Z 库高 )ρg+P A .

[0038] Where: m is the total gas consumption, determined based on the expander's gas consumption per unit time and the number of hours of full-capacity operation; R is the gas constant, 8.314 J / (mol·K); T is the absolute temperature (K); M is the molar mass of the gas; P0 is the pressure at the initial moment of energy release (Pa); Z 上死 Z is the dead water level of the upper reservoir, in meters. 库高 ρ represents the low water level of the gas storage tank, in meters (m); ρ is the density of water, in kilograms per cubic meter of water. 3 g is the acceleration due to gravity; P A The local atmospheric pressure is expressed in Pa.

[0039] The corresponding regulating reservoir capacity V of the upper reservoir of the pumped storage power station -水库 =V -储气 ×K. Where K is the reservoir capacity margin coefficient, and the dead water level of the upper reservoir should meet the inlet and outlet water pipe flooding depth requirements.

[0040] The flow rate of inlet and outlet pipe 2 is q=V -储气 / t, where t is the number of hours of full operation.

[0041] The construction method for a gas storage system based on the above structure is as follows:

[0042] 1) Gas storage excavation and support: Excavation shall be carried out using the drill-and-blast method or the TBM method. During the construction period, steel mesh and shotcrete anchor support shall be installed according to the surrounding rock conditions, and a system of anchor bolts shall be set.

[0043] 2) Grouting of the excavated surrounding rock foundation shall be carried out by grouting without cover. During grouting, cracks shall be filled with grouting material. After grouting, the permeability shall meet the control standard of not more than 3Lu.

[0044] 3) Apply a waterproof layer to the shotcrete surface using a spraying method;

[0045] 4) Reinforcing steel fabrication and installation, installation of reinforcing steel mesh for concrete lining, laying of pressure-regulating water supply pipes, pressure-relieving drainage pipes and pressure-regulating perforated pipes, and burial of backfill grouting pipes;

[0046] 5) Corrugated steel lining installation: The corrugated steel lining can be installed in sections or pieces, and welded on site and inspected for compliance.

[0047] 6) Pour the flexible concrete lining layer, and backfill and grout after it reaches the grouting age.

[0048] In summary, the technical solution provided in this application also has the following advantages:

[0049] 1. Improving the volume utilization rate of the gas storage facility increases energy storage density, reduces gas pressure, decreases the storage volume, and lowers the cost. For a 300MW compressed air energy storage power station operating at full capacity for 6 hours, the total air volume is 15,353 tons. When the gas storage facility operates at a constant volume of 6-10 MPa, its volume is 345,000 cubic meters. When operating at a constant pressure of 6.0 MPa, the volume is 215,000 cubic meters.

[0050] 2. Improve the system conversion efficiency of compressed air energy storage. When operating at a sliding pressure of 6-10 MPa, the operating condition range is 60%-100%, and the overall system efficiency is 64.7%; when operating at a constant pressure of 6 MPa, which is basically the optimal design condition, the overall system efficiency can be increased to 69.5%.

[0051] 3. The gas sealing and structural design challenges faced by traditional gas storage facilities under high temperature, high pressure, and pressure cycling conditions are transformed into gas sealing and water permeation control problems under normal temperature and constant pressure conditions. This reduces the complexity of structural design and expands the range of structural materials that can be selected. When operating at 6–10 MPa sliding pressure, the average maximum temperature of the gas storage facility is 86.5℃, while under constant pressure operation, the temperature is 40℃ after compressed air heat exchange. From the perspective of ensuring the safety of the gas storage facility and the efficiency of system operation, the leakage rate of the gas storage facility is generally controlled to be no more than 1%, correspondingly requiring the air permeability of the sealing material to be controlled within 10%. -18 (m³(STP)·m) / (s·m²·Pa) or less. When using the composite sealing structure of the present invention, the water permeability of the sealing material is required to be controlled below 10. -10 Below m / s.

[0052] The technical solution of this application will be further described below through specific embodiments:

[0053] The solution to the technical problem of this invention is as follows: A gas storage facility is connected to a high-level reservoir. During the gas storage facility's exhaust process, water is replenished from the reservoir, causing the gas volume to gradually decrease. The high-level reservoir provides a relatively constant pressure. Simultaneously, the pressure change during inflation and deflation is minimal, and the compressed air in the gas storage facility does not undergo expansion or compression, maintaining a relatively constant temperature. The gas storage facility employs a multi-layered seepage-proof structure, with uniform pressure inside and outside the gas sealing layer. The gas sealing layer has a simple structure and excellent sealing effect. Specific details are as follows.

[0054] 1. System Composition

[0055] The constant temperature and pressure gas storage system mainly includes: a high-level water reservoir, an inlet water pipe connecting the high-level water reservoir and the gas storage tank, a pressure-regulating water supply pipe connecting the inlet and outlet water pipes, a pressure-relief drainage pipe, a multi-layer composite gas storage tank, and valves for maintenance and operation control. For the composition and principle of the constant temperature and pressure gas storage system, see [link to documentation]. Figure 1.

[0056] The multi-layered composite gas storage facility consists of, from the outside in, a natural surrounding rock layer, a surrounding rock reinforcement layer, a wire mesh and sprayed anchor layer, a sprayed waterproof layer, a reinforced concrete lining layer, and a corrugated steel lining layer.

[0057] The surrounding rock is the main load-bearing component. The surrounding rock reinforcement layer, through consolidation grouting, improves the integrity, uniformity, deformation resistance, and seepage prevention performance of the rock mass. Anchor bolts further enhance the integrity and combined load-bearing capacity of the surrounding rock. A wire mesh and shotcrete layer promptly seals the excavated surrounding rock, limiting its unloading deformation and reducing the unevenness of the excavation surface, providing a relatively flat base for the sprayed waterproof layer. The sprayed waterproof layer is a crucial component of the overall seepage prevention capability, directly sprayed onto the surface of the shotcrete. The reinforced concrete lining layer is an important structural measure to limit surrounding rock deformation and ensure its stability, and also a supporting structure to prevent damage to the sprayed waterproof layer under external water conditions. The corrugated steel lining layer is a key structural measure for high-pressure gas sealing. To enhance the rigidity of this layer and prevent buckling instability under internal and external pressure differences, a corrugated shape is used. To enhance the effects of pressure replenishment and drainage, a ring-shaped perforated pipe is installed on the outer layer of the steel pipe. This perforated pipe connects to the pressure replenishment pipe and the pressure relief drainage pipe, and is arranged within the corrugations of the steel lining.

[0058] To facilitate system operation control and maintenance, control valves are installed on the inlet and outlet water pipes, pressure equalization water supply pipes, pressure relief drainage pipes, and gas storage maintenance drainage pipes.

[0059] 2. Working principle

[0060] The elevated reservoir and the gas storage facility are connected by inlet and outlet water pipes. The difference in water level between the elevated reservoir and the gas storage facility, plus atmospheric pressure, constitutes the absolute pressure inside the gas storage facility. Because the water level fluctuations in the elevated reservoir and the gas storage facility are small, while the absolute difference between them is large, the absolute pressure change in the gas storage facility is very small, and it can be considered to be in a constant pressure operating state. The gas pressure change inside the facility is slight, and the temperature remains basically constant during the slow inflation and deflation process.

[0061] A pressure-reducing water supply pipe installed on the outside of the corrugated steel lining connects to the inlet and outlet water pipes to the elevated reservoir. The water in the gas storage tank is also connected to the elevated reservoir via these pipes. Therefore, the pressure inside and outside the corrugated steel lining is balanced, and the structure bears virtually no load during gas storage and release, resulting in minimal stress and deformation. The reinforced concrete lining layer uses flexible concrete, which has a high ultimate tensile value. Combined with the crack-limiting effect of the reinforcing steel, it does not crack under internal water pressure, thus playing a supporting role in waterproofing and reducing internal water seepage. The sprayed waterproof layer has excellent waterproofing performance and deformation capacity. Under the constraint of the inner and outer structural layers, it will not undergo significant lateral deformation leading to tearing damage, making it the main component of the waterproofing system.

[0062] By employing a composite structure for the gas storage facility, the problem of gas permeation under high pressure is decoupled into the gas sealing problem under internal and external pressure balance and the leakage control problem of high-pressure water. Gas is more difficult to seal than water, primarily because of the fundamental differences in the molecular properties, physical behavior, and interactions with sealing materials between gases and liquids.

[0063] 1. Molecular Scale and Motion Characteristics: Gas molecules (such as the main components of air, N2 and O2, with a diameter of ≈0.35nm) are similar in size to water molecules (≈0.275nm), but the distance between gas molecules is much greater than that of liquids (the distance between gas molecules under standard conditions is more than 10 times that of liquids). This makes it easier for gas molecules to "squeeze" into the tiny pores of sealing materials. The thermal motion speed of gas molecules is much higher than that of liquids (the average speed of gas molecules at room temperature is ≈500m / s, while that of water molecules is about 0.5m / s). This higher kinetic energy allows gas molecules to collide with and penetrate the microscopic defects of sealing materials (such as interface gaps and intrinsic micropores) more frequently, resulting in a diffusion capacity far exceeding that of liquids.

[0064] 2. Surface tension and interfacial interactions: Water molecules are polar molecules, and intermolecular hydrogen bonding creates significant surface tension (≈72 mN / m at room temperature). When water encounters tiny pores (such as gaps with a diameter <10 μm), the surface tension forms a "meniscus," generating inward capillary pressure that prevents further water penetration (similar to the "water blockage" effect). Gases have no surface tension, and the intermolecular forces are extremely weak (no surface tension). When encountering pores, they do not need to overcome interfacial tension; they only need to overcome the mechanical barriers of the material to penetrate. Therefore, they can more easily pass through micropores of the same size.

[0065] 3. Differences in permeation mechanisms: The core mechanism for gas permeation through sealing materials is molecular diffusion (following Fick's law), with the permeation rate positively correlated with the concentration gradient (pressure difference) and the molecular diffusion coefficient. Even at low pressures, gas molecules can slowly diffuse through the microporous network within the material. Water permeation is primarily pressure-driven flow, relying on continuous pore channels. Due to the cohesive forces between liquid molecules, water requires sufficient pressure to overcome the pore walls of the material and is easily impeded by adsorption on the surface of the sealing material.

[0066] 4. The "selective blocking" of sealing materials: Most sealing materials (such as rubber, resin, and cement-based materials) have polar groups (such as -OH, -COOH) on their surface or inside, which have a strong affinity for polar water molecules and easily form an adsorbed water film, thus blocking some pores and enhancing their ability to block water. Non-polar gas molecules (such as N2, O2) have extremely weak affinity for sealing materials and are difficult to adsorb, thus more easily forming continuous permeation paths inside the material. Gases, due to their vigorous molecular motion, lack of surface tension, strong diffusion ability, and weak interfacial interaction with sealing materials, are more sensitive to microscopic defects in the sealing structure, making them more difficult to seal than water. The composite structure of the gas storage facility decouples the sealing problem of high-pressure gases, transforming it into a waterproofing and seepage problem with more extensive engineering experience, forming a comprehensive waterproofing system composed of a flexible reinforced concrete lining layer, a sprayed waterproof layer, and a surrounding rock reinforcement layer.

[0067] 3. Design Methodology

[0068] (1) Gas storage capacity

[0069] When operating under constant pressure, since the pressure change is small and the volume gradually decreases during the exhaust process, the gas temperature can be considered as constant. Therefore, the volume of the gas storage tank can be calculated using the following formula:

[0070] ;

[0071] P0=(Z 上死 -Z 库高 )ρg+P A .

[0072] Where: m is the total gas consumption, determined based on the expander's gas consumption per unit time and the number of hours of full-capacity operation; R is the gas constant, 8.314 J / (mol·K); T is the absolute temperature (K); M is the molar mass of the gas; P0 is the pressure at the initial moment of energy release (Pa); Z 上死 Z is the dead water level of the upper reservoir, in meters. 库高 ρ represents the low water level of the gas storage tank, in meters (m); ρ is the density of water, in kilograms per cubic meter of water. 3 g is the acceleration due to gravity; P A The local atmospheric pressure is expressed in Pa.

[0073] (2) High-level reservoir capacity regulation capacity V -水库 =V -储气 ×K, where K is the reservoir capacity margin coefficient. The dead water level of a high-level reservoir should meet the inlet and outlet water pipe flooding depth requirements.

[0074] (3) Inlet and outlet water pipes

[0075] Excessive pipe diameter is uneconomical, while insufficient diameter leads to excessive flow velocity, high head loss, increased compression power consumption during inflation, and decreased pressure during deflation. Technical and economic analysis indicates that controlling the head loss to no more than 1% is the most economical approach. The flow rate of the inlet and outlet pipes is q = V. -储气 / t, where t is the number of hours of full operation.

[0076] .

[0077] Where: q, pipe flow rate, unit: m³ 3 / s; λ, friction resistance system (dimensionless, related to flow regime and pipe roughness), dimensionless; l, total pipe length, in meters; The sum of the local resistance coefficients of all bends ( ), dimensionless; π, pi (≈3.1416), dimensionless; g, gravitational acceleration (taken as 9.81), unit m / s². 2 h, total head (operating head), unit m.

[0078] (4) Sealing design

[0079] The gas sealing function is provided by the corrugated steel lining. Since the water body inside the gas storage tank is connected to the pressure-reducing water supply pipe, leakage occurs in the impermeable layer outside the steel lining, requiring water replenishment during operation, which often incurs operating costs. Based on the project's water supply conditions, a leakage control target should be proposed. Referring to the design experience of pumped storage power stations, a control target of daily leakage *s* not exceeding 0.02%~0.05% of the high-level reservoir capacity can be established.

[0080] .

[0081] Where: V, total storage capacity (designed total volume), unit: m. 3P, Water pressure inside the reservoir (water pressure acting on the impermeable layer, generated by the reservoir water level or gas pressure), Pa; D, Reservoir diameter (cross-sectional diameter of the cylindrical reservoir), in meters; L, Reservoir length (axial length of the cylindrical reservoir), in meters; n, Percentage of allowable leakage to total reservoir capacity (control standard threshold, in %); h1, Thickness of the first impermeable layer (reinforced concrete layer, the main structural impermeability), in meters; K1, Permeability coefficient of the first layer (permeability index of reinforced concrete, the smaller the value, the better the impermeability), in m / s; h2, Thickness of the second impermeable layer (sprayed layer). The waterproofing material layer (such as polyurea, asphalt coating), unit mm to m; K2, second layer permeability system (permeability of the sprayed material), m / s; h3, thickness of the third layer impermeable layer (strengthening the bedrock after grouting and improving the permeability of the natural bedrock), unit m; K3, permeability coefficient of the third layer (permeability of the bedrock after grouting), unit m / s; h4, thickness of the fourth layer (outer ungrouted bedrock, serving as a natural barrier for the impermeable system), unit m; K4, fourth layer permeability system (original permeability of the natural bedrock), unit m; H, head converted from water pressure (hydraulic head driving seepage), formula is... Unit: m; A, total seepage prevention area of ​​the storage tank (side + bottom), formula: Unit m 2 ; The total seepage resistance (sum of series resistances) of multiple impermeable layers is given by the following formula: Unit: s; The actual daily leakage of the storage tank is calculated using the following formula: Unit m 3 / d; Maximum permissible daily leakage (control threshold), unit: m³ 3 / d.

[0082] 4. Construction Method

[0083] The gas storage facility shall be constructed according to the following steps and methods:

[0084] 1) For the excavation and support of the gas storage facility, the drilling and blasting method or the TBM method is used for excavation. During the construction period, steel mesh and shotcrete anchor support are installed according to the surrounding rock conditions, and system anchor bolts are set.

[0085] 2) Grouting of surrounding rock: Grouting without cover is adopted. During grouting, the cracks are filled with filler material. After grouting, the permeability should meet the control standard of not more than 3 Lu.

[0086] 3) Apply a waterproof layer to the sprayed concrete surface using a spraying method.

[0087] 4) Reinforcing steel installation: install the reinforcing steel mesh for the concrete lining, lay water supply pipes, drainage pipes and perforated pipes, and bury backfill grouting pipes.

[0088] 5) Steel lining installation: Corrugated steel linings can be installed in sections or pieces, and welded on site and inspected for compliance.

[0089] 6) Pour flexible lining concrete and backfill with grout after the grouting age has been reached.

[0090] 5. Operating Method

[0091] During the operational preparation phase, after the gas storage facility is constructed, the maintenance control valves of the inlet and outlet water pipes are opened, the pressure equalization control valve is opened, the pressure relief control valve is closed, and the air intake and exhaust control valves are closed. Water from the high-level reservoir enters the gas storage facility and the pressure equalization water supply pipe through the inlet and outlet water pipes, and the internal and external pressures of the corrugated steel lining are balanced.

[0092] During energy storage, the air compressor is started, the intake and exhaust control valves are opened, and the gas storage tank is filled with gas. As the filling process proceeds, the water in the gas storage tank flows to the high-level reservoir through the inlet and outlet water pipes. When the water level in the gas storage tank reaches the designed minimum water level, the gas storage is completed.

[0093] When releasing energy, the intake and exhaust control valves are opened, and the gas storage tank supplies air to the turbine expander. As the compressed air is discharged, water from the high-level reservoir flows into the gas storage tank through the inlet and outlet water pipes. When the water level in the gas storage tank reaches the designed maximum water level, the exhaust is completed.

[0094] During maintenance, first close the maintenance control valves of the inlet and outlet water pipes, then close the pressure equalization control valve, and then open the pressure relief control valve and the gas storage maintenance drain valve in sequence to drain the water. When draining, the water level in the gas storage should be controlled to be higher than the external water pressure of the steel lining to prevent the steel lining from buckling inward under external pressure.

[0095] Example 1

[0096] 1. Project Overview

[0097] A compressed air energy storage power station is located approximately 30km from the load center. Its proximity to the load center and convenient external transportation, coupled with the presence of multiple 500kV substations nearby, ensures easy grid connection. The power station's functions include peak shaving, valley filling, energy storage, frequency regulation, phase regulation, and emergency backup, ensuring the safe and stable operation of the power grid in the load center.

[0098] According to the system plan, the compressed air energy storage power station has an installed capacity of 300MW and a full-load operating time of 4 hours. It mainly includes a compression system, an expansion system, an air storage system, and a heat exchange system.

[0099] 2. Gas storage design

[0100] Based on the preliminary selection of the turbine expander, its gas consumption is 2728.2 t / h. Assuming a planned full-load operation of 6 hours, the total gas consumption is 16369.4 tons, and the gas temperature after heat exchange is 40℃. The preliminary dead water level of the upper reservoir is 1174m, the normal operating water level is 1197m, the gas storage is a corridor-type structure with a diameter of 12m and a center elevation of 565m. The upper limit water level of the gas storage is 571m, the lower limit water level is 559m, the maximum pressure of the gas storage is 1197-559+10=648m, and the minimum pressure is 1174-571+10=613m.

[0101] According to the aforementioned calculation formula, =16369.4×10 3 kg×8.314J / (mol·k)×313.15k÷(648×9.8×1000)Pa÷0.02897(kg / mol)=231657m 3 .

[0102] The gas seal of the gas storage facility uses 6mm corrugated steel plates. The flexible reinforced concrete lining is 60cm thick, designed for easy concrete placement and vibration. The waterproof layer is a 3mm thick water-based rubber spray. The shotcrete layer with wire mesh is 10cm thick, and the system anchor bolts are 6m long with a 3m spacing. The depth of the grouting around the tunnel is 5m, and the grouting qualification standard is 3Lu. Based on parameters such as the deformation modulus of the surrounding rock, and considering reinforcement, the ultimate tensile strength of the concrete must be controlled to be no less than 0.1%.

[0103] 3. Inlet and outlet water pipe design

[0104] The water replenishment volume in 6 hours was 231,657 m³. 3 The flow rate of the inlet water pipe is 10.72 m³ / h. 3 / s, with a total length of 1331m, the pipe material is steel, the head loss is controlled to be no more than 1%, and the pipe diameter is calculated to be 1.65m according to the formula.

[0105] 4. Leakage Calculation

[0106] The total storage capacity of the warehouse is 231,657 m³. 3 The water pressure is 638 m, the gas storage tank has an inner diameter of 12 m, and has four layers of impermeable layers. The first layer is reinforced concrete, 0.6 m thick, with a permeability coefficient of 10. -9 m / s; the second layer is a sprayed waterproof material, 3mm thick, with a permeability coefficient of 7.8×10. -13 cm / s; the third layer is bedrock reinforced with grout, with a thickness of 5m and a permeability coefficient of 3×10 cm / s; -5 cm / s; outside the bedrock, the permeability coefficient is 10×10 cm / s; -5 cm / s. Calculate the daily leakage rate to be 11.04 m³.3 The percentage is approximately 0.0048%, which is far below the design control standard of 0.1% to 1%, indicating that the seepage prevention system is effective and the risk of leakage is extremely low.

Claims

1. An air storage system for compressed air energy storage power stations, characterized in that: The gas storage system includes a gas storage body and a constant temperature and pressure regulating mechanism. The inner cavity of the constant temperature and pressure regulating mechanism is connected to the inner cavity of the gas storage body. The gas pressure and temperature of the gas stored in the gas storage body are always maintained within a specified pressure and temperature range under the regulation of the regulating medium delivered by the constant temperature and pressure regulating mechanism. The constant temperature and pressure regulating mechanism includes at least the upper reservoir (1) of the pumped storage power station. The regulating medium is the regulating water stored in the upper reservoir. The upper reservoir (1) is connected to the gas storage body through inlet and outlet water pipes (2). The absolute pressure of the gas in the gas storage body is the sum of the elevation pressure difference between the water level of the upper reservoir and the water level of the gas storage body plus atmospheric pressure. The structure includes at least an excavated rock foundation (6), a protective reinforcement structure, and a gas storage inner tube (7). The inner wall of the excavated rock foundation (6) is constructed and reinforced by the protective reinforcement structure, which surrounds the outer wall of the gas storage inner tube (7). The protective reinforcement structure includes at least a sprayed waterproof layer (8) and a reinforced concrete lining layer (9). The sprayed waterproof layer (8) and the reinforced concrete lining layer (9) are arranged sequentially from the inside to the outside on the inner wall of the excavated rock foundation (6). The gas storage inner tube (7) is attached to the inner wall of the excavated rock foundation (6) with the cooperation of the reinforced concrete lining layer (9). The protective reinforcement structure also includes a wire mesh sprayed anchor layer (1). 0), The wire mesh sprayed anchor layer (10) is arranged between the sprayed waterproof layer (8) and the inner wall of the excavated surrounding rock foundation (6). The reinforced concrete lining layer (9) is sequentially fixed between the sprayed waterproof layer (8) and the sprayed waterproof layer (8) and the wire mesh sprayed anchor layer (10). The gas storage tank body includes a sealing and leak-proof pressure equalization mechanism. The gas storage tank inner tube (7) is made of corrugated steel lining. The sealing and leak-proof pressure equalization mechanism is arranged on the outside of the corrugated steel lining. The pressure inside and outside the corrugated steel lining is kept balanced by the pressure equalization medium output by the sealing and leak-proof pressure equalization mechanism. The sealing and leak-proof pressure equalization mechanism includes multiple pressure equalization pipes (11), one pressure equalization water supply pipe (12) and one pressure relief drainage pipe (13). Vertically set Each pressure regulating pipe (11) is sequentially attached to the outside of the corrugated steel lining in a circumferential direction. Each pressure regulating pipe (11) has multiple pressure regulating medium spray holes spaced apart on the wall surface facing the corrugated steel lining. One end of the pressure equalization water supply pipe (12) is connected to the inlet and outlet water pipe (2), and the other end of the pressure equalization water supply pipe (12) is connected to the input end of each pressure regulating pipe (11). The input end of the pressure relief drain pipe (13) is connected to the output end of each pressure regulating pipe (11). The outer side of each pressure regulating pipe (11) that is not in contact with the corrugated steel lining is attached to the reinforced concrete lining layer (9). The pressure inside and outside the corrugated steel lining is kept balanced by the pressure regulating medium output from each pressure regulating pipe.

2. The air storage system for a compressed air energy storage power station according to claim 1, characterized in that: Waterway maintenance valve (3), water inlet and outlet control valve (4), and gas storage maintenance and drainage valve (5) are also installed on the inlet and outlet water pipes (2).

3. The air storage system for a compressed air energy storage power station according to claim 1 or 2, characterized in that: The storage capacity of the gas storage facility is calculated using the following formula: ； P0=(Z 上死 -WITH 库高 )ρg+P A ; Where: m is the total gas consumption, determined based on the expander's gas consumption per unit time and the number of hours of full-capacity operation; R is the gas constant, 8.314 J / (mol·K); T is the absolute temperature (K); M is the molar mass of the gas; P0 is the pressure at the initial moment of energy release (Pa); Z 上死 Z is the dead water level of the upper reservoir, in meters. 库高 ρ represents the low water level of the gas storage tank, in meters (m); ρ is the density of water, in kilograms per cubic meter of water. 3 g is the acceleration due to gravity; P A The local atmospheric pressure is in Pa. The regulating capacity V of the upper reservoir of a pumped storage power station -水库 =V -储气 ×K; where: K is the reservoir capacity margin coefficient, and the dead water level of the upper reservoir should meet the inlet and outlet water pipe inlet submersion depth requirements; The flow rate q=V of the inlet and outlet pipes (2) -储气 / t, where t is the number of hours of full operation.

4. A construction method for building the gas storage system for a compressed air energy storage power station as described in claim 3, characterized in that, The gas storage system is constructed according to the following steps: 1) Gas storage excavation and support: Excavation shall be carried out using the drill-and-blast method or the TBM method. During the construction period, steel mesh and shotcrete anchor support shall be installed according to the surrounding rock conditions, and a system of anchor bolts shall be set. 2) Grouting of the excavated surrounding rock foundation shall be carried out by grouting without cover. During grouting, cracks shall be filled with grouting material. After grouting, the permeability shall meet the control standard of not more than 3Lu. 3) Apply the waterproof layer by spraying when spraying concrete surfaces; 4) Reinforcing steel fabrication and installation, installation of reinforcing steel mesh for concrete lining, laying of pressure-regulating water supply pipes, pressure-relieving drainage pipes and pressure-regulating perforated pipes, and burial of backfill grouting pipes; 5) Corrugated steel lining installation: The corrugated steel lining shall be installed in sections and pieces, welded on site, and inspected for compliance. 6) Pour the flexible concrete lining layer, and backfill and grout after it reaches the grouting age.

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