Water pressure balance type cavern compressed air energy storage bank and construction method

Abstract

The invention provides a water pressure balance type cavern compressed air energy storage reservoir and a construction method, and belongs to the technical field of compressed air energy storage. The compressed air energy storage reservoir comprises a ground reservoir unit, an underground cavern unit and a flexible support unit; the underground cavern unit comprises a gas storage cavern, an upper connecting roadway, a lower connecting roadway, an air injection and exhaust vertical shaft and a water injection and drainage vertical shaft; the first ends of the multiple gas storage caverns are connected through the upper connecting roadway, and the second ends of the multiple gas storage caverns are connected through the lower connecting roadway. The bottoms of the gas injection and exhaust vertical shafts distributed in the vertical direction are connected with the upper connecting roadway. The bottoms of the water injection and drainage vertical shafts distributed in the vertical direction are connected with the lower connecting roadway, and the tops of the water injection and drainage vertical shafts distributed in the vertical direction are connected with the ground reservoir unit. The method has the technical effect that the technical problem that in the frequent inflation and deflation process of an existing compressed air energy storage power station, a surrounding rock and a supporting structure are excessively damaged due to cyclic alternating loads is effectively solved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of compressed air energy storage, and particularly relates to a water pressure balanced rock cave compressed air energy storage and a construction method. BACKGROUND

[0002] Energy storage is an indispensable important component in the future new power system dominated by new energy. As an important type of energy storage, compressed air energy storage has unique advantages that other types of energy storage such as pumped storage and electrochemical energy storage do not have, and has great development potential. Compared with pumped storage, compressed air energy storage has a short construction period, relatively easy site selection, high ecological environmental friendliness, and small immigration and relocation problems; compared with the current mature lithium battery energy storage, compressed air energy storage has a long service life, many cycle times, good safety, no pollution, no system performance degradation, and compressed air energy storage has frequency and pressure regulation performance similar to traditional thermal power and rotational inertia and short-circuit current support, which is conducive to the safe and stable operation of the power system in the future high proportion of new energy scenarios.

[0003] Since compressed air energy storage has a wide range of applications in different scenarios such as power supply side and power grid side of the power system, developing key technology research of compressed air energy storage and promoting the application of compressed air energy storage technology can increase the consumption of renewable energy such as wind and solar energy.

[0004] Rock cave compressed air energy storage only needs to select a hard and complete rock mass, and the site selection suitability is much better than other construction modes, and has great development space. At present, the underground compressed air energy storage is mainly designed by sliding pressure. Since the pressure of the gas stored in the cave is continuously changing, the surrounding rock and the supporting structure are always subjected to the damage of cyclic alternating load, and a secondary lining and a steel sealing ring need to be set to ensure the air tightness, so the construction technology is difficult. In view of this, a water pressure balanced rock cave compressed air energy storage and a construction method are needed to further improve the compressed air technology and reduce the construction technology difficulty. SUMMARY

[0005] The present application aims to at least solve one of the technical problems existing in the prior art, and provides a new technical solution of a water pressure balanced rock cave compressed air energy storage and a construction method.

[0006] According to a first aspect of the present application, a water pressure balanced rock cave compressed air energy storage is provided, comprising a ground water storage pool unit, an underground cave unit and a flexible supporting unit; wherein the ground water storage pool unit is located on the ground, the underground cave unit is located underground, and the underground cave unit is supported on the surrounding rock through the flexible supporting unit. The underground cavern unit comprises a gas storage cavern, an upper connecting gallery, a lower connecting gallery, a gas injection and exhaust shaft, and a water injection and exhaust shaft; a first end of each of the gas storage caverns is connected through the upper connecting gallery, and a second end of each of the gas storage caverns is connected through the lower connecting gallery; the upper connecting gallery is close to an upper portion of the gas storage cavern, and the lower connecting gallery is close to a lower portion of the gas storage cavern. A bottom of the gas injection and exhaust shaft distributed in a vertical direction is connected with the upper connecting gallery, and a top of the gas injection and exhaust shaft is used for passing in compressed air; a bottom of the water injection and exhaust shaft distributed in a vertical direction is connected with the lower connecting gallery, and a top of the water injection and exhaust shaft is connected with the ground reservoir unit.

[0007] Optionally, a height of a longitudinal section of the gas storage cavern along a width direction is 25m-30m; and a span of the longitudinal section of the gas storage cavern along the width direction is 15m-20m.

[0008] Optionally, both ends of the gas storage cavern are in a stepped shape, and a height of the stepped shape is the same as a height of the upper connecting gallery or the lower connecting gallery.

[0009] Optionally, the gas storage cavern has a constant working pressure, and a buried depth of the gas storage cavern is higher than a water head value of the constant working pressure by 20m.

[0010] According to a second aspect of the present application, a construction method of a water pressure balanced rock cavern compressed air energy storage is provided, which is applied to the water pressure balanced rock cavern compressed air energy storage according to the first aspect, and comprises the following steps: Selecting a site for the compressed air energy storage, and calculating a constant pressure inside a storage cavern; Determining a longitudinal section shape of the gas storage cavern along a width direction according to a use requirement of the compressed air energy storage, a rock mass strength, a geological structure, a stress state of surrounding rock, and a ground stress condition; Calculating a buried depth of the storage cavern according to the constant pressure inside the storage cavern; According to the longitudinal section shape of the gas storage cavern along the width direction and the buried depth of the storage cavern, adopting the new Austrian tunneling method to construct the compressed air energy storage; wherein the underground cavern unit is supported on the surrounding rock through the flexible support unit.

[0011] Optionally, when a storage capacity of the gas storage cavern is lower than or equal to 500,000m3, the gas injection and exhaust shaft and the water injection and exhaust shaft are used as a construction access and a deslagging channel; and when the storage capacity of the gas storage cavern is higher than 500,000m3, a slope gallery is arranged as an auxiliary deslagging channel.

[0012] Optionally, a slope of the slope gallery is 30%.

[0013] Optionally, when the site is selected, siliceous and ferruginous sandstone, microcrystalline and micritic limestone, granite, anorthosite, and orthogneiss are selected as the surrounding rock.

[0014] Optionally, the rock mass permeability coefficient of the surrounding rock is less than 1E-07 m / s.

[0015] Optionally, smooth blasting excavation is adopted during construction.

[0016] One technical effect of the present application is that: In the embodiments of the present application, the present application does not need to use devices such as submersible pumps or lifting pumps, but only uses underground water in a ground water storage pool unit to keep the pressure of compressed air in a gas storage cavern constant to improve power generation efficiency, and through control of water level changes of the ground water storage pool unit, dynamic compensation of volume changes of compressed gas in the gas storage cavern is realized, so that the pressure of the entire compressed air energy storage library is kept stable during the charging and discharging process of the gas storage cavern.

[0017] Therefore, the greatest advantage of the present application is that the pressure in the library is constant during operation, the surrounding rock and the supporting structure do not bear the alternating load during the operation of the traditional compressed air energy storage library, the rigid lining structure does not need to be arranged on the wall of the cavern, and only the flexible supporting unit is arranged to excite and utilize the self-stabilizing ability of the surrounding rock, so as to form a cooperative bearing system of the surrounding rock and the supporting structure, effectively solving the technical problems such as excessive damage of the surrounding rock and the supporting structure caused by the cyclic alternating load during the frequent charging and discharging process of the existing compressed air energy storage power station, and the device parameters can be adjusted according to the actual working conditions, so that the optimization space is large. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 FIG. 1 is a structural schematic diagram of a water pressure balance type rock cavern compressed air energy storage library according to an embodiment of the present application; Figure 2 FIG. 2 is a structural schematic diagram of an underground cavern unit of a water pressure balance type rock cavern compressed air energy storage library according to an embodiment of the present application; Figure 3 FIG. 3 is a sectional structure schematic diagram of a gas storage cavern in various working conditions according to an embodiment of the present application; wherein (a) is a sectional structure schematic diagram of a gas storage cavern in working condition 1 according to an embodiment of the present application; (b) is a sectional structure schematic diagram of a gas storage cavern in working condition 2 according to an embodiment of the present application; (c) is a sectional structure schematic diagram of a gas storage cavern in working condition 3 according to an embodiment of the present application; and (d) is a sectional structure schematic diagram of a gas storage cavern in working condition 4 according to an embodiment of the present application; Figure 4These are deformation cloud maps of the gas storage caverns after excavation for various working conditions according to embodiments of the present invention; wherein, (a) is a deformation cloud map of the gas storage cavern after excavation for working condition 1 according to embodiments of the present invention; (b) is a deformation cloud map of the gas storage cavern after excavation for working condition 2 according to embodiments of the present invention; (c) is a deformation cloud map of the gas storage cavern after excavation for working condition 3 according to embodiments of the present invention; and (d) is a deformation cloud map of the gas storage cavern after excavation for working condition 4 according to embodiments of the present invention. Figure 5 These are schematic diagrams showing the depth of the loosened rock zone of the sidewall after excavation for various working conditions according to embodiments of the present invention; wherein, (a) is a schematic diagram showing the depth of the loosened rock zone of the sidewall after excavation for working condition 1 according to embodiments of the present invention; (b) is a schematic diagram showing the depth of the loosened rock zone of the sidewall after excavation for working condition 2 according to embodiments of the present invention; (c) is a schematic diagram showing the depth of the loosened rock zone of the sidewall after excavation for working condition 3 according to embodiments of the present invention; and (d) is a schematic diagram showing the depth of the loosened rock zone of the sidewall after excavation for working condition 4 according to embodiments of the present invention. Figure 6 This is a diagram of the support structure for a gas storage cavern in Class I surrounding rock, as described in an embodiment of the present invention. Figure 7 This is a diagram of the support structure for a gas storage cavern in Class II surrounding rock, as described in an embodiment of the present invention. Figure 8 This is a diagram of the support structure for a gas storage cavern in Class III surrounding rock, as described in an embodiment of the present invention. Figure 9 This is a diagram of the support structure for a gas storage cavern in Class IV surrounding rock, as described in this embodiment of the invention. Figure 10 This is a diagram of the support structure for a gas storage cavern in Class V surrounding rock, as described in an embodiment of the present invention.

[0019] In the diagram: 1. Gas storage chamber; 2. Upper connecting tunnel; 3. Lower connecting tunnel; 4. Injection and exhaust shaft; 5. Injection and drainage shaft; 6. Surface water storage unit. Detailed Implementation

[0020] Various exemplary embodiments of this application will now be described in detail with reference to the accompanying drawings. It should be noted that, unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps set forth in these embodiments do not limit the scope of this application.

[0021] Embodiments of the present application will be described in detail below, examples of which are shown in the drawings, wherein the same or similar notations represent the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by referring to the drawings are exemplary only, for the purpose of explanation, and are not to be understood as limiting the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0022] The terms "first", "second" in the description and claims of the present application can explicitly or implicitly include one or more of the features. In the description of the present application, the meaning of "a plurality of" is two or more, unless otherwise specified. In addition, "and / or" in the specification and claims means at least one of the connected objects, and the character " / ", generally means that the front and rear associated objects are in an "or" relationship.

[0023] In the description of the present application, it should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the purpose of facilitating the description of the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application.

[0024] In the description of the present application, it should be noted that unless otherwise explicitly specified and limited, the terms "mounting", "connecting", "connecting" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the communication inside two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0025] According to the first aspect of the present application, referring to Figures 1 to 10 , a water pressure balanced rock cave compressed air energy storage library is provided, which has important application value for various underground engineering and underground space projects such as underground compressed air energy storage library, underground compressed carbon dioxide energy storage library, etc.

[0026] Specifically, referring to Figure 1 and Figure 2The water pressure balanced rock cavern compressed air energy storage library comprises a ground reservoir unit 6, an underground cavern unit and a flexible support unit (not shown in the figure); wherein the ground reservoir unit is located on the ground, the underground cavern unit is located underground, and the underground cavern unit is supported on the surrounding rock through the flexible support unit; The underground cavern unit comprises gas storage caverns 1, upper connecting roadways 2, lower connecting roadways 3, gas injection and exhaust shafts 4 and water injection and exhaust shafts 5; a plurality of first ends of the gas storage caverns 1 are connected through the upper connecting roadways 2, a plurality of second ends of the gas storage caverns 1 are connected through the lower connecting roadways 3, the upper connecting roadways 2 are close to the upper parts of the gas storage caverns 1, and the lower connecting roadways 3 are close to the lower parts of the gas storage caverns 1. The bottoms of the gas injection and exhaust shafts 4 distributed in the vertical direction are connected with the upper connecting roadways 2, and the tops are used for entering compressed air; the bottoms of the water injection and exhaust shafts 5 distributed in the vertical direction are connected with the lower connecting roadways 3, and the tops are connected with the ground reservoir unit 6.

[0027] In the embodiments of the present application, the device does not need to use a submersible pump or a lifting pump, but only uses underground water in the ground reservoir unit to keep the pressure of compressed air in the gas storage cavern 1 constant to improve the power generation efficiency, and dynamic compensation of the volume change of compressed gas in the gas storage cavern 1 is realized by controlling the water level change of the ground reservoir unit, so that the pressure stability of the entire compressed air energy storage library during the charging and discharging process of the gas storage cavern 1 is maintained.

[0028] Therefore, the biggest advantage of the present application is that the pressure in the library is constant during operation, the surrounding rock and the support structure do not bear the alternating load during the operation of the traditional compressed air energy storage library, the rigid lining structure does not need to be arranged on the cave wall, only the flexible support unit is arranged to excite and utilize the self-stability of the surrounding rock, and a cooperative bearing system of the surrounding rock and the support structure is formed, technical problems such as excessive damage of the surrounding rock and the support structure caused by the cyclic alternating load during the frequent charging and discharging process of the existing compressed air energy storage power station are effectively solved, and the device parameters of the gas storage cavern 1 can be adjusted according to the actual working conditions, so that the optimization space is large.

[0029] For example, the number of gas storage caverns is arranged according to the scale of the energy storage power station and the ground land area, for example, the design volume of the gas storage cavern in the embodiment is 50,000 square meters, the net cross-sectional volume of the gas storage cavern is 543 square meters, and theoretically the length of the gas storage cavern should be about 92 m. However, the ground land area only allows the arrangement of a gas storage cavern with a length of about 50 m, so two storage caverns (L≈46 m) are arranged, as shown in Figure 1 If the ground land area allows the arrangement of a gas storage cavern with a length of about 92 m, one storage cavern (L≈92 m) can be arranged.

[0030] Optionally, the height of the longitudinal section of the gas storage cavern along the width direction is 25m-30m; the span of the longitudinal section of the gas storage cavern along the width direction is 15m-20m. This helps to improve the stability of the surrounding rock support.

[0031] For example, the cross-sectional shape of the gas storage chamber is a flat-bottomed horseshoe shape.

[0032] Optionally, the two ends of the gas storage cavern are stepped, and the height of the stepped portion is the same as the height of the upper or lower connecting tunnel. For example, in this embodiment, the height of the upper and lower connecting tunnels is set to 6m, so the height of the stepped portion of the gas storage cavern is 6m.

[0033] In the above embodiments, it is helpful for groundwater in the surface water storage unit to enter or exit the interior of the gas storage chamber through the injection and drainage shafts and the lower connecting tunnels, and it is also helpful for compressed air to enter or exit the interior of the gas storage chamber through the injection and exhaust shafts and the lower connecting tunnels.

[0034] Optionally, the gas storage chamber has a constant working pressure, and the burial depth of the gas storage chamber is 20m higher than the head value of the constant working pressure.

[0035] In the above embodiments, the burial depth of the gas storage cavern is reasonably designed, which helps to achieve static compensation of the gas storage cavern to improve energy storage efficiency.

[0036] For example, the formula for calculating the burial depth of a gas storage cavity is as follows: H=H cavern +H water； In the above formula, H cavern The vertical distance from the vault of the gas storage cavern to the design groundwater level, in meters; H water The design water level is the vertical distance from the ground, expressed in meters (m).

[0037] H cavern =H P +20; In the above formula, H P The head value is calculated based on the constant operating pressure of the gas storage cavern, and the unit is meters (m).

[0038] Furthermore, the constant operating pressure of the gas storage cavern can be converted into a head value using the following formula: H P =P / (ρ×g); In the above formula, P is the design pressure (gauge pressure) of the gas storage chamber, which is related to the conversion efficiency of the compressor and is usually set to 6-7 MPa; ρ is the density of water, taken as 1.0 × 10⁻⁶. 3 kg / m 3g is the acceleration due to gravity, taken as 9.8 N / kg.

[0039] Taking this embodiment as an example, the working pressure of the gas storage cavern is 6 MPa, which translates to a water head of 612.2 m. Therefore, the burial depth of the gas storage cavern from the design groundwater level is approximately 622.2 m. The vertical distance H from the design water level to the ground surface in this embodiment is... water If the depth is 10m, then the final ground depth of the gas storage cavern is approximately 632.2m.

[0040] This invention has the advantages of large scale, high relevance, high reliability, convenient operation, low cost, and wide applicability. It solves the problems of small scale, high cost, and low efficiency of existing compressed air energy storage. It has invented a complete system solution including the underground structure composition of water pressure balanced rock cavern compressed air energy storage, as well as the design and calculation methods for the burial depth, cross-section, and support structure of the gas storage cavern, the construction scheme of the energy storage, and the important auxiliary design such as the inclined tunnel setting mechanism for slag removal. It only requires the selection of hard rock strata with moderate strength to meet all construction requirements, has extremely high tolerance for geological conditions, and has a wide range of applications.

[0041] According to a second aspect of the present invention, a method for constructing a water pressure-balanced cavern compressed air energy storage facility is provided, applicable to the water pressure-balanced cavern compressed air energy storage facility as described in the first aspect, comprising: Site selection for compressed air energy storage facilities and calculation of constant pressure inside the storage chamber; for example, blocky, homogeneous rock masses with minimal weak structural planes, low permeability, and mechanical stability are preferred. The longitudinal cross-sectional shape (i.e., cross-sectional shape) of the gas storage cavern along the width direction is determined based on the usage requirements of the compressed air energy storage, rock mass strength, geological structure, stress state of the surrounding rock, and geostress. The burial depth of the storage chamber is calculated based on the constant pressure inside the storage chamber; Based on the longitudinal cross-sectional shape of the gas storage cavern along its width and the burial depth of the storage cavern, the New Austrian Tunneling Method (NATM) is used to construct the compressed air energy storage facility; wherein, the underground cavern unit is supported by the surrounding rock through the flexible support unit.

[0042] In the above embodiments, the construction method of the water pressure balanced rock cave compressed air energy storage is reasonably designed, which helps to ensure the safe and stable operation of the compressed air energy storage.

[0043] For example, the geometry of a gas storage cavern directly affects stress distribution and is one of the important factors in the stability of the surrounding rock. The cross-sectional shape and size of the gas storage cavern need to be determined comprehensively based on usage requirements, rock mass strength, geological structure, stress state of the surrounding rock, and geostress conditions, combined with engineering experience, engineering analogies, and stability calculations.

[0044] Table 1 shows the cross-sectional forms of the main chambers of large caverns that have been built or are under construction. Based on engineering experience, a circular arch with straight walls is suitable for hard, well-integrated rock masses. For poor geological conditions or high ground stress, horseshoe or elliptical cross-sections are preferable. For surrounding rock where the primary failure mode is hard block failure, the influence of cross-sectional shape on the formation of unstable blocks should be considered. Simultaneously, the construction capabilities and reasonable operating range of machinery should be taken into account to maximize the efficiency of construction machinery.

[0045] Table 1 is a statistical table of the cross-sectional forms of oil storage caverns in existing or under-construction water-sealed underground reservoirs.

[0046] This embodiment, based on the aforementioned principle for determining the cross-sectional shape of the gas storage cavern, uses a common cross-sectional area of ​​543 cubic meters as the standard and compares four different cross-sectional shapes, referencing... Figure 3 As shown: 1) Figure 3 (a) (i.e., working condition 1) is the most frequently used cross-sectional form in engineering practice. Its advantages are that the scheme is simple and easy to construct, and it can ensure a good balance between engineering safety and economy.

[0047] 2) Figure 3 In option (b) (i.e., working condition 2), the excavation face is flat-bottomed and horseshoe-shaped. The main difference between this option and option 1 lies in the different sidewall designs. Overall, this option features a predominantly curved excavation face, which is beneficial for surrounding rock stability and offers relatively better engineering safety. 3) Figure 3 (c) (i.e., operating condition 3) Figure 3 In scenario (d) (i.e., working condition 4), a sloping sidewall replaces the straight sidewall in scheme 1, and is suspended in place. Empirically, this is not conducive to the stability of the surrounding rock of the sidewall. Figure 3 (c) Figure 3 The difference in (d) lies in whether the bottom corners are transitioned with curves.

[0048] It should be noted that, Figure 3 , Figure 4 , Figure 5 (a) in the text all correspond to working condition 1 (i.e., scheme 1). Figure 3 , Figure 4 , Figure 5 (b) in the above all correspond to working condition 2 (i.e., scheme 2); Figure 3 , Figure 4 , Figure 5 (c) in the text all correspond to working condition 3 (i.e., scheme 3); Figure 3 , Figure 4 , Figure 5 (d) in the text all correspond to working condition 4 (i.e. scheme 4).

[0049] To simplify the calculation, each of the above working conditions is simulated using a two-step excavation method. Specifically, the first step is to excavate the upper arch area, and the second step is to excavate the lower sidewall area.

[0050] Based on the accumulated experience in water conservancy and hydropower engineering, when the quality category of the surrounding rock of the cave is Class II to III, the span and height of the cave are both within 30m, and the difference in span and height parameters is not significant, or in other words, the straight sidewall characteristics of the main cave are not prominent and the structural form is good, empirically speaking, the surrounding rock of the cave can have good conditions for cave formation.

[0051] From the perspective of surrounding rock deformation stability, for potential deformation problems, the curved cross-section can, to a certain extent, weaken the release of confining pressure stress during the excavation process. That is, under the premise of curved cross-section, a high stress level can be maintained in the surrounding rock, which plays a positive role in tunneling conditions and surrounding rock stability. This feature has a particularly prominent impact on the sidewall.

[0052] Based on the above understanding, in comparison Figure 3 Based on the surrounding rock deformation stability angle, the four cross-sectional shapes shown have the following empirical understanding regarding the sidewalls and arch: 1) Sidewalls: Compared with other cross-section schemes, the curved scheme in Scheme 2 can achieve the best sidewall stability conditions; considering the difference in the free-standing conditions, the sidewall stability of Scheme 1 is the second best; the sidewalls of Schemes 3 and 4 are inverted and suspended, and have the worst stability.

[0053] 2) Arch: Schemes 3 and 4 have the largest arch curvature, which has the conditions and inherent mechanisms to maintain stress level and enhance arch effect. Due to the stability of arch formation and deformation, the deformation stability of arches in Schemes 1 and 2 is relatively inferior.

[0054] Overall, considering factors such as the requirements for surrounding rock stability, construction convenience, and economy, and taking into account that the main chamber of the water pressure balance rock cave compressed air energy storage of this invention has a burial depth of more than 600m, the stability of the surrounding rock of the high sidewalls should be given special attention. Therefore, Scheme 2 is the final scheme, and the project safety is relatively better.

[0055] The above understanding can be further verified using numerical analysis methods, serving as a direct complement between empirical analysis and numerical evaluation results. Specifically, regarding the four cross-sectional morphologies examined in this analysis, Figure 4 The corresponding results of surrounding rock deformation distribution characteristics are presented. Considering that the potential failure mode of cavern confining pressure is not a stress-type mode, deformation response is used as the evaluation index for scheme comparison.

[0056] See Figure 4The analysis reveals that, under given geological conditions, the excavation deformation of the surrounding rock of caverns with different cross-sectional shapes generally exhibits a consistent pattern, implying that the cross-sectional shape scheme is insufficient to cause changes in the potential failure mode of the surrounding rock of the cavern; (Comparison) Figure 4 The distribution of maximum principal stress shown in (a) further verifies the qualitative judgment on the potential instability mechanism of the surrounding rock, as the basic property that the significant deformation area generally matches the stress relaxation area is consistent with the maximum principal stress distribution.

[0057] Moreover, the differences between different cross-sectional morphology schemes are mainly reflected in the different degrees of deformation of the surrounding rock. Figure 4 (c) Figure 4 In option (d), the sidewalls of the cavern have poor open-air conditions, specifically, the sidewalls are overhanging. When they combine with the rock strata in a further unfavorable way, the maximum deformation can reach 50 mm or more. Compared to the other option... Figure 4 (c) Figure 4 (d) in Figure 4 (a) Figure 4 (b) The sidewall shape can provide better stability, as evidenced by a reduction in both deformation and range. When the sidewall adopts a curved transition, the degree of excavation unloading is further reduced, directly reflected in... Figure 4 Option (b) in this context minimizes the deformation risk of the surrounding rock in the cavern, thus ensuring stability and engineering safety. Figure 4 Option (b) is the optimal solution.

[0058] Figure 5 Furthermore, the calculation results of the relaxation zone depth of the surrounding rock of the cavern sidewall are presented under different cross-sectional conditions and corresponding to different cross-sectional schemes. Figure 5 (a) to Figure 5 The quantization relaxation depths (d) in the figures are 5.6m, 4.8m, 7m, and 7m, respectively. Figure 5 (c) Figure 5 The maximum relaxation depths of the (d) sidewalls are roughly equivalent. Figure 5 (a) is the next best option. Figure 5 (b) has the lowest sidewall relaxation depth, reaching less than 5m, i.e. Figure 5 (b) is the optimal solution from the perspective of surrounding rock stability.

[0059] In this embodiment, the biggest advantage of the pressure-balanced compressed air energy storage tank in the rock cavern is the presence of a ground-level water storage unit (i.e., a closed-loop water storage tank) to balance pressure changes during the energy storage and release processes, ensuring stable pressure inside the tank and output pressure. Therefore, the tank maintains constant pressure during operation, and the surrounding rock and support structure do not bear the alternating loads experienced during the operation of traditional compressed air energy storage tanks, which is beneficial to the stability of the surrounding rock within the cavern.

[0060] In addition, the water pressure balance type rock cave compressed air energy storage is buried more than 600m underground. The hydrostatic pressure of the surrounding rock is consistent with the operating pressure inside the storage. That is, during operation, the surrounding rock is closer to the original unexcavated state. Therefore, the surrounding rock only needs to be equipped with a flexible support structure of shotcrete + steel mesh + grid steel frame (for adverse geological sections). The core idea of ​​the underground structure support is to reasonably control the deformation of the surrounding rock, stimulate and utilize the self-stabilizing ability of the surrounding rock, and form a collaborative bearing system between the surrounding rock and the support structure.

[0061] According to Article 4.1.1 of the "Technical Specification for Rock and Soil Anchor and Shotcrete Support Engineering" (GB50086-2015), the design of anchor and shotcrete support should preferably adopt the engineering analogy method, and when necessary, should be combined with monitoring and measurement methods and theoretical verification methods. In this embodiment, the support design of the gas storage cavern was determined by analogy with the "Technical Specification for Rock and Soil Anchor and Shotcrete Support Engineering" (GB50086-2015) and by referring to the design and construction experience of domestic and international projects. Furthermore, although the surrounding rock conditions vary greatly from project to project, the deformation around the cavern, the stress variation law of the surrounding rock, and the stress characteristics of the support are generally consistent. Based on preliminary support parameters derived from various surrounding rock classification parameters and engineering experience, combined with the specific geological conditions of this embodiment, and in accordance with the promulgated national standards "Technical Specification for Rock and Soil Anchor and Shotcrete Support Engineering" (GB 50086-2015), "Design Standard for Underground Water-Sealed Rock Cavern Oil Depots" (GB / T 50455-2020), and "Code for Design of Concrete Structures" (GB 50010-2010, 2015 edition), the final determined gas storage cavern support structure is as follows: Figures 6-10 As shown.

[0062] See Figure 6 The gas storage cavern is divided into four levels from top to bottom. The system anchor bolts are 25 mm in diameter, 6 m long, and spaced 2.0 x 2.0 m in a staggered pattern. Furthermore, the surrounding rock surface is sprayed with 100 mm thick CF30 steel fiber reinforced concrete. Additionally, the main cavern floor slab is made of 100 mm thick C25 concrete.

[0063] See Figure 7 The gas storage cavern is divided into four levels from top to bottom. The system anchor bolts are 25 mm in diameter, 6 m long, and spaced 2.0 x 1.5 m in a staggered pattern. Furthermore, the surrounding rock surface is sprayed with 150 mm thick CF30 steel fiber reinforced concrete. Additionally, the main cavern floor slab is made of 100 mm thick C25 concrete.

[0064] See Figure 8The gas storage cavern is divided into four levels from top to bottom. The system anchor bolts are 25 mm in diameter, 6 m long, and spaced 1.5 x 1.5 m in a staggered pattern. Furthermore, the surrounding rock surface is sprayed with 200 mm thick CF30 steel fiber reinforced concrete. Additionally, the main cavern floor slab is made of 100 mm thick C25 concrete.

[0065] See Figure 9 The gas storage cavern is divided into four levels from top to bottom. The system anchor bolts are 25 mm in diameter, 6 m long, and spaced 1.5 x 1.0 m in a staggered pattern. Furthermore, the surrounding rock surface is sprayed with 250 mm thick CF30 steel fiber reinforced concrete. Additionally, the main cavern floor slab is made of 100 mm thick C25 concrete.

[0066] See Figure 10 The gas storage cavern is divided into four levels from top to bottom. The system anchor bolts are 25 mm in diameter, 6 m long, and spaced 1.0 x 1.0 m in a staggered pattern. Furthermore, the surrounding rock surface is sprayed with 350 mm thick CF30 steel fiber reinforced concrete. Additionally, the main cavern floor slab is made of 200 mm thick C25 concrete.

[0067] Optionally, when the gas storage cavern's capacity is 500,000 cubic meters or less, the air injection / venting shaft and water injection / drainage shaft serve as access and slag removal channels for construction. When the gas storage cavern's capacity exceeds 500,000 cubic meters, an inclined tunnel is provided as an auxiliary slag removal channel. The soil sections of the air injection / venting shaft and water injection / drainage shaft employ initial support using the inverted shaft wall method combined with secondary lining using the conventional method. For rock masses below moderate weathering, blasting excavation combined with anchor spraying support is used. Slag is lifted out of the shaft using a hoist bucket and stored at a temporary slag dump at the shaft opening for unified transportation.

[0068] In the above implementation method, setting up an inclined tunnel to assist in slag removal is more economical and saves construction time.

[0069] Optionally, the inclined shaft has a slope of 30% and uses a rail-guided muck discharge system. This helps ensure the muck discharge efficiency of the discharge channel.

[0070] It should be noted that the slope of the inclined roadway is 30%, using rail-mounted muck removal, which is a conventional design and has been seen in many cases in mining (especially coal and metal mines) and tunnel engineering. If the New Austrian Tunneling Method (NATM) blasting is used and muck is removed by muck trucks, the slope needs to be controlled within 13%, mainly due to the safe climbing performance of the transport vehicles. This application aims to reduce the total length of the construction roadway and uses rail-mounted muck removal instead of muck trucks, thus allowing the slope to be increased to 30%. The anti-slip and support scheme after the construction of the 30% inclined roadway is a conventional design. Anti-slip measures usually involve laying heavy steel rails on the surface of the inclined roadway to increase the stability of the rail-mounted muck removal. In actual engineering, stability calculations should be performed based on geological survey data and in accordance with national standards GB / T 50455 or JTG 3370.1-2018, typically using a shotcrete and anchor support design. Since the total cross-sectional dimensions of the inclined roadway are relatively small and it does not bear the alternating load of high-pressure gas, its support scheme is not the focus of this invention.

[0071] Furthermore, the 30% slope of the inclined shaft is conventionally designed based on Article 12.3.3 of the "Specifications for Design of Highway Tunnels, Volume 1: Civil Engineering" (JTG 3370.1-2018). The inclination angle of the inclined shaft for various hoisting methods should comply with the following regulations: 1) When lifting a skip with rails, the angle should not exceed 35°; 2) When hoisting a mine car along the rails, the angle should not exceed 25°; 3) When lifting the belt conveyor, the angle should not exceed 15°; 4) When transporting without tracks, the angle should not exceed 7°.

[0072] This application uses a railcar to lift and remove slag. The 30% slope is converted to an inclination angle of 16.7°, which does not exceed the 25° limit in the specification.

[0073] Alternatively, siliceous and ferruginous sandstone, microcrystalline and micritic limestone, granite, plagioclase, and orthophyllite can be selected as the surrounding rock during site selection. This helps to ensure the stability of the surrounding rock.

[0074] Optionally, the permeability coefficient of the surrounding rock is less than 1E-07 m / s.

[0075] In the above implementation, the permeability coefficient of the reservoir rock mass (i.e., the surrounding rock mass) is preferably selected to be low to very low permeability, and usually rock masses with a permeability coefficient lower than 1E-07m / s are selected for reservoir construction to reduce the grouting cost of underground engineering.

[0076] In this embodiment, the main advantage of the pressure-balanced rock cavern compressed air energy storage system is its high degree of geological freedom. The prerequisite for constructing underground rock caverns is a blocky, homogeneous body with minimal weak structural planes, low permeability, and mechanical stability. These rock masses are typically sedimentary rocks, massive carbonate rocks, and igneous or metamorphic crystalline rocks. The surrounding rock should be selected in areas with uniform lithology, hard texture, intact rock mass, simple structure, few developed structural planes, integral structure, and a thin, evenly distributed weathering layer. Thick to very thick layers of siliceous and ferruginous sandstone, microcrystalline and micritic limestone, granite, plagioclase, and orthophyllite are preferred to reduce the support costs of underground engineering.

[0077] In addition, in terms of topography, priority should be given to low hills and mountains with intact, wide, low and flat terrain. If it is a mountainous area, priority should be given to areas with intact bedrock, flat terrain, simple landform conditions, low mountains and small elevation differences, so as to reduce the leveling cost of ground engineering.

[0078] Alternatively, smooth blasting excavation can be used during construction.

[0079] In the above embodiments, disturbance to the surrounding rock can be reduced, protecting its original strength. Moreover, it can be promptly sealed into a ring, allowing the surrounding rock to undergo a certain degree of controllable deformation, but not exceeding a critical value. This releases some stress through plastic deformation, while timely support limits excessive deformation, thus promoting a new stable state for the surrounding rock.

[0080] In this application embodiment, in order to systematically provide a complete set of technologies and solutions for the underground structure and construction of water pressure balanced rock cavern compressed air energy storage, so as to promote the progress of long-term energy storage technology and ensure the healthy development of the energy storage economy, this invention, based on the construction principle of water pressure balanced rock cavern compressed air energy storage and the functional requirements of static compensation constant pressure storage, and starting from engineering practice, has invented a complete set of system solutions, including the underground structure composition of water pressure balanced rock cavern compressed air energy storage, the design and calculation methods of the burial depth, cross-section and support structure of the gas storage cavern, as well as the construction scheme of the energy storage and important auxiliary designs such as the inclined tunnel setting mechanism for auxiliary slag removal. It only requires the selection of hard rock strata with moderate strength to meet all construction requirements, has extremely high tolerance for geological conditions, and is applicable to multiple scenarios such as different engineering geology, different hydrogeology, and different underground engineering layouts. By integrating various ground facilities, underground units, structures, and devices, this method provides a large-scale, highly targeted, highly reliable, easy-to-operate, low-cost, and widely applicable approach for the construction of water pressure balanced rock cavern compressed air energy storage. It can be quickly applied to the construction of long-term compressed air energy storage, effectively reducing the cost of compressed air storage, improving economic efficiency, and thus promoting the healthy development of the energy storage industry chain.

[0081] It should be noted that, firstly, this invention addresses the problem that existing energy storage technologies mainly focus on salt cavern energy storage, pipeline steel energy storage, and electrochemical energy storage, which are greatly limited by geological structure, geographical resources, and site location, resulting in significant limitations and inapplicability. This invention solves the technical problems of existing compressed air energy storage power stations, such as small energy storage scale, low efficiency, high cost, and difficult site selection, and is of great significance for overcoming the bottleneck of long-term energy storage construction.

[0082] Secondly, this invention solves the technical problems of long-term damage to the surrounding rock and support structure under the pressure cycle of existing cavern compressed air storage, as well as the need for technically challenging underground structures such as reinforced concrete lining and steel sealing rings. It has invented a complete system solution, from the underground structure composition of the water pressure balance cavern compressed air energy storage, to the design and calculation methods of the burial depth, cross-section and support structure of the gas storage cavern, to the construction plan of the energy storage and important auxiliary designs such as the inclined tunnel setting mechanism for auxiliary slag removal. It only requires the selection of hard rock strata with moderate strength to meet all construction requirements, has a very high tolerance for geological conditions, and has a wide range of applications.

[0083] Thirdly, the arrangement, burial depth, cross-section and support structure of the gas storage chamber in the water pressure balance type compressed air storage tank of the present invention can be appropriately adjusted according to the actual working conditions, and the optimization space is large.

[0084] Fourthly, the water pressure balance type compressed air energy storage tank of the present invention can be used not only for compressed air energy storage, but also for compressed carbon dioxide energy storage, which is of great value for new energy storage.

[0085] Fifthly, this invention integrates various underground units, structures, and devices to provide a large-scale, highly targeted, highly reliable, easy-to-operate, low-cost, and widely applicable method for constructing water pressure balanced rock cavern compressed air energy storage. It can be quickly applied to the construction of long-term compressed air energy storage, effectively reducing the cost of compressed air storage, improving economic efficiency, and thus promoting the healthy development of the energy storage industry chain.

[0086] It is understood that the above embodiments are merely exemplary implementations used to illustrate the principles of the present invention, and the present invention is not limited thereto. For those skilled in the art, various modifications and improvements can be made without departing from the spirit and essence of the present invention, and these modifications and improvements are also considered to be within the scope of protection of the present invention.

Claims

1. A water pressure balanced compressed air energy storage tank for rock caverns, characterized in that, It includes a surface water storage tank unit, an underground cavern unit, and a flexible support unit; wherein the surface water storage tank unit is located above ground, the underground cavern unit is located underground, and the underground cavern unit is supported by the flexible support unit to the surrounding rock; The underground cavern unit includes a gas storage cavern, an upper connecting tunnel, a lower connecting tunnel, an air injection / venting shaft, and an air injection / drainage shaft; the first ends of multiple gas storage caverns are connected by the upper connecting tunnel, and the second ends of multiple gas storage caverns are connected by the lower connecting tunnel; the upper connecting tunnel is located near the upper part of the gas storage cavern, and the lower connecting tunnel is located near the lower part of the gas storage cavern; The bottom of the vertically distributed air injection and exhaust shafts is connected to the upper connecting tunnel, and the top is used to introduce compressed air; the bottom of the vertically distributed water injection and drainage shafts is connected to the lower connecting tunnel, and the top is connected to the ground water storage tank unit.

2. The water pressure balanced rock cave compressed air energy storage tank according to claim 1, characterized in that, The height of the longitudinal section of the gas storage cavern along the width direction is 25m-30m; the span of the longitudinal section of the gas storage cavern along the width direction is 15m-20m.

3. The water pressure balanced rock cave compressed air energy storage tank according to claim 1, characterized in that, The gas storage chamber has stepped ends, and the height of the stepped portion is the same as the height of the upper or lower connecting tunnel.

4. The water pressure balanced rock cavern compressed air energy storage tank according to claim 1, characterized in that, The gas storage chamber has a constant working pressure, and the burial depth of the gas storage chamber is 20m higher than the head value of the constant working pressure.

5. A method for constructing a water pressure balanced rock cavern compressed air energy storage facility, characterized in that, The hydraulically balanced compressed air storage tank for rock caverns as described in any one of claims 1 to 4 comprises: Site selection for compressed air energy storage facility and calculation of constant pressure inside storage chamber; The longitudinal cross-sectional shape of the gas storage cavern along the width direction is determined based on the usage requirements of the compressed air energy storage, rock mass strength, geological structure, stress state of the surrounding rock, and in-situ stress. The burial depth of the storage chamber is calculated based on the constant pressure inside the storage chamber; Based on the longitudinal cross-sectional shape of the gas storage cavern along its width and the burial depth of the storage cavern, the New Austrian Tunneling Method (NATM) is used to construct the compressed air energy storage facility; wherein, the underground cavern unit is supported by the surrounding rock through the flexible support unit.

6. The construction method of the water pressure balanced rock cave compressed air energy storage facility according to claim 5, characterized in that, When the storage capacity of the gas storage cavern is less than or equal to 500,000 cubic meters, the gas injection and exhaust shafts and the water injection and drainage shafts serve as access and slag removal channels for construction; when the storage capacity of the gas storage cavern is greater than 500,000 cubic meters, an inclined tunnel is set up as an auxiliary slag removal channel.

7. The construction method of the water pressure balanced rock cave compressed air energy storage facility according to claim 6, characterized in that, The slope of the inclined tunnel is 30%.

8. The construction method of the water pressure balance type compressed air energy storage tank in a rock cave according to claim 7, characterized in that, When selecting a site, siliceous and ferruginous sandstone, microcrystalline and micritic limestone, granite, plagioclase, and orthogne were chosen as the surrounding rocks.

9. The construction method of the water pressure balance type compressed air energy storage tank in a rock cave according to claim 8, characterized in that, The permeability coefficient of the surrounding rock is less than 1E-07 m / s.

10. The construction method of the water pressure balance type compressed air energy storage tank in a rock cave according to claim 9, characterized in that, Smooth blasting excavation was used during construction.

Images