Compressed air energy storage system and operation method thereof

Abstract

The invention relates to the technical field of compressed air energy storage, in particular to a compressed air energy storage system and an operation method thereof.The compressed air energy storage system comprises an energy storage assembly, an energy release assembly, a plurality of heat exchange medium storage tank sets and a buried gas storage spherical tank, and the energy storage assembly comprises an air compression unit, a multi-stage heat exchanger and a multi-stage cooler; the energy release assembly comprises an air expansion unit and a multi-stage heater; the heat exchange medium storage tank group comprises at least one cold storage tank and at least one heat storage tank; the plurality of heat exchange medium storage tank groups are respectively communicated with the multi-stage heat exchanger and the multi-stage heater; the buried gas storage spherical tank is arranged underground, the input end is connected with the air compression unit, and the output end is connected with the air expansion unit. According to the compressed air energy storage system, multi-stage heat storage and gradient utilization of a heat source can be achieved, and the efficiency of the energy storage system is improved; the buried gas storage spherical tank is deeply buried underground, so that the risk of breakage of the spherical tank body and the production cost are reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of compressed air energy storage, and in particular to a compressed air energy storage system and an operating method thereof. Background Art

[0002] Compressed air energy storage power generation technology is a high-density, long-life, high-efficiency, and flexible physical energy storage technology that can enhance the peak-shaving capacity of the power grid and improve the reliability of the power supply of the power grid. Compressed air energy storage power generation equipment includes four systems: air compression system, heat storage system, gas storage system, and expansion power generation system. The working process is divided into energy storage process and energy release process.

[0003] During the energy storage process, the air compression system, heat storage system, and gas storage system work, using electrical energy to compress the air to high pressure and store it in the gas storage reservoir. The waste heat generated during the compression process is used to heat water, and the heated water is stored in the high-temperature water tank. During the energy release process, the gas storage system, heat storage system, and expansion power generation system work, the water in the high-temperature water tank heats the high-pressure air, the heated high-pressure air enters the expansion power generation system, and the heated high-pressure air is used for expansion power generation, and the cooled water is stored in the low-temperature water tank.

[0004] Generally speaking, the higher the gas storage pressure of the compressed air energy storage unit, the higher the unit efficiency. However, as the gas storage pressure continues to increase, the pressure resistance requirements for related equipment such as gas storage tanks will increase dramatically, and high-strength, thicker-walled materials are needed to manufacture gas storage equipment, which not only greatly increases the equipment cost, but also increases the difficulty of manufacturing. When the pressure is too high, the equipment faces increased safety risks such as leakage and rupture. In addition, during the energy storage process, the operating conditions of the existing final-stage air compressor are not stable. As the energy storage time increases, the pressure of the gas reservoir gradually increases, and the output power of the air compressor also gradually increases. Its exhaust temperature also gradually increases with the increase of energy storage time. The temperature is low at the beginning of operation, and the temperature variation range is large, which has a certain negative impact on the utilization of waste heat.

[0005] Based on the above, the present invention provides a compressed air energy storage system and an operation method thereof to solve the problems existing in the prior art. Summary of the invention

[0006] The present invention aims to provide a compressed air energy storage system and an operation method thereof. The specific technical scheme is as follows:

[0007] A compressed air energy storage system, comprising:

[0008] An energy storage component, the energy storage component comprising an air compression unit, a multi-stage heat exchanger and a multi-stage cooler, the air compression unit is connected to the multi-stage heat exchanger and the multi-stage cooler, and the multi-stage heat exchanger and the multi-stage cooler are arranged in series along the flow direction of compressed air;

[0009] An energy release component, the energy release component comprises an air expansion unit and a multi-stage heater, the air expansion unit is connected to the multi-stage heater;

[0010] A plurality of heat exchange medium storage tank groups, wherein the heat exchange medium storage tank groups include at least one cold storage tank and at least one heat storage tank; the plurality of heat exchange medium storage tank groups are respectively connected to a multi-stage heat exchanger and a multi-stage heater;

[0011] The buried ball storage tank is arranged below the ground, the input end of the buried ball storage tank is connected to the air compression unit, and the output end of the buried ball storage tank is connected to the air expansion unit.

[0012] Further, at least one group of heat exchange medium storage tanks is connected to the heat exchanger at the end of the air compression unit and the heater at the head end of the air expansion unit;

[0013] The output end of the cold storage tank is connected to the input end of the heat exchanger, and the input end of the cold storage tank is connected to the output end of the heater;

[0014] The input end of the heat storage tank is connected to the output end of the heat exchanger, and the output end of the heat storage tank is connected to the input end of the heater;

[0015] A pressure balance pipe is provided between the cold storage tank and the heat storage tank of each heat exchange medium storage tank group.

[0016] Furthermore, the air compression unit comprises a multi-stage air compressor arranged in series, wherein the air inlet end of the first-stage air compressor is connected to the atmosphere, and the air outlet end of the last-stage air compressor is connected to the input end of the buried ball storage tank; the air inlet end of the first-stage air compressor is provided with an air filter;

[0017] The air expansion unit comprises a multi-stage air expander arranged in series, wherein the air inlet end of the first-stage air expander is connected to the output end of the buried ball storage tank, and the air outlet end of the last-stage air expander is connected to the atmosphere;

[0018] The air outlet end of each stage of the air compressor is connected to at least one set of heat exchangers and coolers, and the air inlet end of each stage of the air expander is connected to at least one set of heaters.

[0019] Furthermore, the buried ball storage tank is set at a depth of h underground, so that Ph≈(P1+P2) / 2, wherein Ph is the soil pressure outside the buried ball storage tank, Ph=soil density*9.8*h, P1 is the pressure after the buried ball storage tank outputs compressed air, and P2 is the pressure after the buried ball storage tank inputs compressed air.

[0020] Furthermore, the buried ball storage tank includes a tank body and a support seat, and the tank body is arranged on the support seat; the tank body includes a shell and an inner support assembly, and the inner support assembly is supported inside the shell.

[0021] Furthermore, the inner support assembly includes a central column, ribs, multiple support rods and multiple pads, the two ends of the central column are connected to the shell through pads, the multiple support rods are connected to the central column through the ribs, and the multiple support rods are connected to the shell through pads.

[0022] Furthermore, the plurality of support rods are symmetrically distributed and the angles α between two adjacent support rods are equal;

[0023] The angle α can be any one of 90°, 60°, 45°, 36° and 30°.

[0024] Furthermore, a plurality of reinforcing ribs are staggeredly arranged on the outside of the shell, and the distance between two adjacent reinforcing ribs on the spherical surface is 700 mm to 1000 mm;

[0025] An anti-corrosion layer is also provided outside the shell, and the thickness of the anti-corrosion layer is 6 mm to 12 mm.

[0026] Furthermore, it also includes a cooling system, which includes a cooling tower, and the cooling tower is connected to a multi-stage cooler.

[0027] A method for operating a compressed air energy storage system, operating the compressed air energy storage system described above, comprising the following steps:

[0028] Energy storage stage: The air compression unit compresses the air to generate high-pressure air. The cold water medium in the cold storage tank flows into the multi-stage heat exchanger to recover the heat in the air to generate hot water and store it in the heat storage tank. The cooled high-pressure air is output to the buried spherical storage tank.

[0029] Energy release stage: the air expansion unit expands the high-pressure air output by the buried ball storage tank, and the hot water medium in the heat storage tank flows into the multi-stage heater to heat the high-pressure air output by the buried ball storage tank and the air expanded by the air expansion unit, and the hot water medium after heat exchange cooling is output to the cold storage tank.

[0030] The application of the technical solution of the present invention has the following beneficial effects:

[0031] (1) The present invention provides a compressed air energy storage system, comprising an energy storage component, an energy release component, a plurality of heat exchange medium storage tank groups and an underground spherical storage ball tank, wherein the energy storage component comprises an air compression unit, a multi-stage heat exchanger and a multi-stage cooler, wherein the air compression unit is connected to the multi-stage heat exchanger and the multi-stage cooler, and the multi-stage heat exchanger and the multi-stage cooler are arranged in series along the flow direction of compressed air; the energy release component comprises an air expansion unit and a multi-stage heater, wherein the air expansion unit is connected to the multi-stage heater; the heat exchange medium storage tank group comprises at least one cold storage tank and at least one heat storage tank; the plurality of heat exchange medium storage tank groups are respectively connected to the multi-stage heat exchanger and the multi-stage heater; the underground spherical storage ball tank is arranged below the ground, wherein the input end of the underground spherical storage ball tank is connected to the air compression unit, and the output end of the underground spherical storage ball tank is connected to the air expansion unit. In the present invention, through the coordinated use of energy storage components, energy release components and multiple groups of heat exchange medium storage tank groups, multi-level heat storage and cascade utilization of heat sources can be achieved, which is beneficial to improving the efficiency of the energy storage system; using an underground spherical storage ball tank and burying it deep underground can reduce the total pressure on the spherical tank body, reduce the risk of rupture of the spherical tank body, and reduce production costs.

[0032] (2) In the present invention, the underground spherical gas storage tank is buried deep underground, so even if leakage or rupture occurs, the external damage caused is smaller.

[0033] (3) In the present invention, the buried ball storage tank is buried underground at a depth of h, so that Ph≈(P1+P2) / 2. The outside of the spherical tank body is subjected to soil pressure, and the inside is subjected to gas pressure. The soil pressure can offset part of the pressure of the gas in the spherical tank body, which correspondingly reduces the total pressure borne by the spherical tank body and reduces the risk of rupture or leakage of the spherical tank body.

[0034] (4) In the present invention, the outer shell of the buried ball storage tank is staggered with reinforcing ribs, and the inner shell is provided with a central column, rib plates, support rods and pads to assist the shell in bearing the gas pressure, which can reduce the shell wall thickness to a certain extent and reduce the manufacturing difficulty and cost of the spherical tank body.

[0035] (5) In the present invention, the buried spherical energy storage tank is buried deep underground, the surrounding soil temperature is constant, and the temperature change of the gas in the spherical tank body during the day and night and throughout the year is relatively small, which is conducive to the efficient and stable operation of the compressed air energy storage system.

[0036] (6) In the present invention, the shell splicing steel plates of the buried spherical storage tank shell are sealed and welded by sealing channel steel, thereby reducing the probability of leakage or rupture of the spherical tank body.

[0037] (7) In the present invention, two groups of heat exchange medium storage tanks are used for two-stage heat storage, wherein at least one group of heat exchange medium storage tanks is connected to the heat exchanger at the end of the air compression unit and the heater at the head end of the air expansion unit (to realize the utilization of low-quality thermal energy), thereby realizing the cascade utilization of heat sources, which is beneficial to improving the efficiency of the energy storage system.

[0038] (8) The present invention provides an operating method for a compressed air energy storage system, which realizes two-stage heat storage and cascade utilization of heat sources, thereby improving the efficiency of the energy storage system.

[0039] In addition to the above-described purposes, features and advantages, the present invention has other purposes, features and advantages. The present invention will be further described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] The drawings constituting a part of this application are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0041] Figure 1 is a schematic diagram of the overall structure of a compressed air energy storage system in an embodiment of the present invention;

[0042] Figure 2 Schematic diagram of the structure of the buried ball storage tank in the embodiment of the present invention, wherein (a) is a front view, (b) is a front cross-sectional view, and (c) is a top cross-sectional view;

[0043] Figure 3 Schematic diagram of external facilities of the buried spherical ball storage tank in an embodiment of the present invention;

[0044] Figure 4 It is a schematic diagram of the local structure of the shell;

[0045] Figure 5 Schematic diagram of the pressure borne by the buried spherical ball storage tank in the embodiment of the present invention;

[0046] Among them, 1. Energy storage component, 1.1. Primary air compressor, 1.2. Secondary air compressor, 1.3. Third-stage air compressor, 1.4. Fourth-stage air compressor, 1.5. Air filter, 1.6. Primary heat exchanger, 1.7. Primary cooler, 1.8. Secondary heat exchanger, 1.9. Secondary cooler, 1.10. Third-stage heat exchanger, 1.11. Third-stage cooler, 1.12. Fourth-stage heat exchanger, 1.13. Fourth-stage cooler, 2. Energy release component, 2.1. Primary air expander, 2.2. Secondary air expander, 2.3. Third-stage air expander, 2.4. Fourth-stage air expander, 2.5. Primary heater, 2.6. Secondary heater, 2.7. Third-stage heater, 2.8. Fourth-stage heater, 2.9. Generator, 3. Heat exchange medium storage tank group, 3.1. #1 heat storage tank, 3.2. #2 heat storage tank, 3.3. #1 cold storage tank, 3.4. #2 cold storage tank, 4. Buried spherical storage ball tank, 4.1. Support seat, 4.2. Shell, 4.2.1. #1 shell splicing steel plate, 4.2.2. #2 shell splicing steel plate, 4.2.3. Sealing channel steel, 4.2.4. Weld between splicing steel plates, 4.2.5. Weld between sealing channel steel and #1 shell splicing steel plate, 4.2.6. Weld between sealing channel steel and #2 shell splicing steel plate, 4.3. Center column, 4.4. Rib plate, 4.5. Support rod, 4.6. Pad, 4.7. Reinforcement rib, 4.8. Anti-corrosion layer, 4.9. Manhole door, 5. Cooling system, 6. Sump, 7. Drainage pump, 8. Stairwell. DETAILED DESCRIPTION

[0047] The embodiments of the present invention are described in detail below with reference to the accompanying drawings. However, the present invention can be implemented in many different ways as defined and covered.

[0048] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside" and "outside" etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0049] In addition, the terms "first", "second", etc. are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first", "second", etc. may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "plurality" means two or more.

[0050] Example

[0051] See also Figure 1 The present invention provides a compressed air energy storage system, including an energy storage component 1, an energy release component 2, a plurality of heat exchange medium storage tank groups 3 and an underground type air storage ball tank 4:

[0052] The energy storage component 1 includes an air compression unit, a multi-stage heat exchanger and a multi-stage cooler. The air compression unit is used to compress air to generate high-pressure air; the air compression unit is connected to the multi-stage heat exchanger and the multi-stage cooler, and the multi-stage heat exchanger and the multi-stage cooler are arranged in series along the flow direction of compressed air. The heat exchanger is used to exchange heat with the high-pressure air, and the cooler is used to cool the high-pressure air after heat exchange.

[0053] In this embodiment, see Figure 1 The air compression unit includes a first-stage air compressor 1.1, a second-stage air compressor 1.2, a third-stage air compressor 1.3 and a fourth-stage air compressor 1.4 which are arranged in series, wherein the air inlet end of the first-stage air compressor 1.1 is connected to the atmosphere, and the air outlet end of the fourth-stage air compressor 1.4 is connected to the input end of the buried ball storage tank 4; the air inlet end of the first-stage air compressor 1.1 is provided with an air filter 1.5, and the air filter 1.5 filters the air before entering the first-stage air compressor 1.1.

[0054] In this embodiment, four stages of heat exchangers and four stages of coolers are used, namely, the first stage heat exchanger 1.6, the first stage cooler 1.7, the second stage heat exchanger 1.8, the second stage cooler 1.9, the third stage heat exchanger 1.10, the third stage cooler 1.11, the fourth stage heat exchanger 1.12, and the fourth stage cooler 1.13. The outlet end of each stage of the air compressor is connected to a set of heat exchangers and coolers, see Figure 1 A first-stage heat exchanger 1.6 and a first-stage cooler 1.7 are arranged in series between the first-stage air compressor 1.1 and the second-stage air compressor 1.2, a second-stage heat exchanger 1.8 and a second-stage cooler 1.9 are arranged in series between the second-stage air compressor 1.2 and the third-stage air compressor 1.3, a third-stage heat exchanger 1.10 and a third-stage cooler 1.11 are arranged in series between the third-stage air compressor 1.3 and the fourth-stage air compressor 1.4, and a fourth-stage heat exchanger 1.12 and a fourth-stage cooler 1.13 are arranged in series at the air outlet end of the fourth-stage air compressor 1.4.

[0055] The energy release component 2 includes an air expansion unit and a multi-stage heater. The air expansion unit is connected to the multi-stage heater, which is used to heat the high-pressure air output by the buried ball storage tank 4; the end of the air expansion unit is connected to the generator 2.9 to realize high-pressure air expansion and power generation.

[0056] In this embodiment, see Figure 1The air expansion unit includes a first-stage air expander 2.1, a second-stage air expander 2.2, a third-stage air expander 2.3 and a fourth-stage air expander 2.4 arranged in series, wherein the air inlet end of the first-stage air expander 2.1 is connected to the output end of the buried ball storage tank 4, and the air outlet end of the fourth-stage air expander 2.4 is connected to the atmosphere.

[0057] In this embodiment, four-stage heaters are used, namely, a first-stage heater 2.5, a second-stage heater 2.6, a third-stage heater 2.7 and a fourth-stage heater 2.8. The air inlet end of each stage of the air expander is connected to a group of heaters, see Figure 1 The air inlet end of the first-stage air expander 2.1 is connected to a first-stage heater 2.5, a second-stage heater 2.6 is connected between the first-stage air expander 2.1 and the second-stage air expander 2.2, a third-stage heater 2.7 is connected between the second-stage air expander 2.2 and the third-stage air expander 2.3, and a fourth-stage heater 2.8 is connected between the third-stage air expander 2.3 and the fourth-stage air expander 2.4.

[0058] The heat exchange medium storage tank group 3 includes at least one cold storage tank and at least one heat storage tank; multiple groups of heat exchange medium storage tank groups 3 are respectively connected to multi-stage heat exchangers and multi-stage heaters; at least one group of heat exchange medium storage tank groups 3 is connected to the heat exchanger at the end of the air compression unit and the heater at the head end of the air expansion unit.

[0059] In this embodiment, two groups of heat exchange medium storage tank groups 3 are provided, and each group of heat exchange medium storage tank groups 3 includes a cold storage tank and a heat storage tank, namely #1 heat storage tank 3.1 and #1 cold storage tank 3.3, #2 heat storage tank 3.2 and #2 cold storage tank 3.4; pressure balance pipes are provided between #1 heat storage tank 3.1 and #1 cold storage tank 3.3, and between #2 heat storage tank 3.2 and #2 cold storage tank 3.4.

[0060] In this embodiment, the output end of the #1 cold storage tank 3.3 is connected to the input end of the four-stage heat exchanger 1.12, and the output end of the four-stage heat exchanger 1.12 is connected to the input end of the #1 heat storage tank 3.1; the output end of the #1 heat storage tank 3.1 is connected to the input end of the first-stage heater 2.5, and the output end of the first-stage heater 2.5 is connected to the input end of the #1 cold storage tank 3.3.

[0061] The output end of the #2 cold storage tank 3.4 is respectively connected to the input ends of the primary heat exchanger 1.6, the secondary heat exchanger 1.8 and the tertiary heat exchanger 1.10, and the output ends of the primary heat exchanger 1.6, the secondary heat exchanger 1.8 and the tertiary heat exchanger 1.10 are respectively connected to the input end of the #2 heat storage tank 3.2; the output end of the #2 heat storage tank 3.2 is respectively connected to the input ends of the secondary heater 2.6, the tertiary heater 2.7 and the quaternary heater 2.8, and the output ends of the secondary heater 2.6, the tertiary heater 2.7 and the quaternary heater 2.8 are respectively connected to the input end of the #2 cold storage tank 3.4.

[0062] During the energy storage process, the cold water in the #1 cold storage tank 3.3 flows into the four-stage heat exchanger 1.12 to recover the heat in the high-pressure air, and then enters the #1 heat storage tank 3.1 for storage; the cold water in the #2 cold storage tank 3.4 flows into the first-stage heat exchanger 1.6, the second-stage heat exchanger 1.8 and the third-stage heat exchanger 1.10 respectively to recover the heat in the high-pressure air, and then enters the #2 heat storage tank 3.2 for storage.

[0063] During the energy release process, the hot water in the #1 heat storage tank 3.1 enters the first-stage heater 2.5 to heat the air, and then enters the #1 cold storage tank 3.3 after heat exchange cooling; the hot water in the #2 heat storage tank 3.2 enters the second-stage heater 2.6, the third-stage heater 2.7 and the fourth-stage heater 2.8 to heat the air, and then enters the #2 cold storage tank 3.4 after heat exchange cooling.

[0064] In the present invention, since the operation of the first three stages of air compressors is stable and the exhaust temperature is maintained at a high level, high-quality heat storage can be achieved; the efficiency of the second, third and fourth stage air expanders is relatively high, and the shaft power is high, and the contribution to power generation is large, so high-quality thermal energy is used preferentially; the fourth stage air compressor is always in a variable operating state, the exhaust temperature varies greatly, and the temperature is relatively low, which can be used to recover low-quality thermal energy; the first stage air expander has a large throttling loss and a large inlet pressure variation range, so its efficiency and output shaft power are low. Therefore, the low-quality heat recovered from the output end of the fourth stage air compressor is used in the first stage heater 2.5 to heat the air, realizing the step-by-step utilization of heat storage and improving the efficiency of the energy storage system.

[0065] It also includes a cooling system 5, which includes a cooling tower. The cooling tower is connected to the multi-stage cooler. During the energy storage process, the cooling tower recovers high-temperature cooling water in the primary cooler 1.7, the secondary cooler 1.9, the tertiary cooler 1.11 and the quaternary cooler 1.13. After being cooled in the cooling tower to become low-temperature cooling water, the water enters the primary cooler 1.7, the secondary cooler 1.9, the tertiary cooler 1.11 and the quaternary cooler 1.13 to cool the air and circulate it.

[0066] The buried ball storage tank 4 is arranged below the ground, the input end of the buried ball storage tank 4 is connected to a four-stage air compressor, and the output end of the buried ball storage tank 4 is connected to a first-stage air expander.

[0067] See also Figure 5The buried ball storage tank 4 is set at a depth of h underground (h is the distance from the ground to the top of the buried ball storage tank), so that Ph≈(P1+P2) / 2, wherein Ph is the soil pressure outside the buried ball storage tank 4, Ph=soil density*9.8*h, P1 is the pressure after the buried ball storage tank 4 outputs compressed air, and P2 is the pressure after the buried ball storage tank 4 inputs compressed air.

[0068] See also Figure 2 In (a)-(c), the buried ball storage tank 4 includes a tank body and a support seat 4.1, and the tank body is arranged on the support seat 4.1; the tank body includes a shell 4.2 and an inner support assembly, and the inner support assembly is supported inside the shell 4.2.

[0069] The inner support assembly includes a central column 4.3, ribs 4.4, multiple support rods 4.5 and multiple pads 4.6. The central column 4.3 is arranged at the inner center position of the spherical tank body. Both ends of the central column 4.3 are connected to the shell 4.2 through pads 4.6. Multiple support rods 4.5 are connected to the central column 4.3 through ribs 4.4, and multiple support rods 4.5 are connected to the shell 4.2 through pads 4.6.

[0070] The plurality of support rods 4.5 are symmetrically distributed and the angle α between two adjacent support rods 4.5 is equal; the angle α can be any one of 90°, 60°, 45°, 36° and 30°.

[0071] In this embodiment, the central column 4.3 can withstand a tensile force of (P2-Ph)×π×1 / 4×D 2 Determine, where D is the inner diameter of the housing 4.2.

[0072] The support rod 4.5 can withstand the tensile force according to (P2-Ph)×2×π×1 / 4×D 2 ÷(n / 2), where n is the number of support rods 4.5.

[0073] A plurality of reinforcing ribs 4.7 are staggeredly arranged on the outside of the shell 4.2, and the distance between two adjacent reinforcing ribs 4.7 on the spherical surface is 700 mm to 1000 mm, so as to increase the strength of the shell 4.2.

[0074] In this embodiment, the outer portion of the shell 4.2 of the buried ball storage tank 4 is staggered with reinforcing ribs 4.7, and the inner portion of the shell 4.2 is provided with a central column 4.3, ribs 4.4, support rods 4.5 and pads 4.6 to assist the shell 4.2 in withstanding the gas pressure, which can reduce the wall thickness of the shell 4.2 to a certain extent, and reduce the manufacturing difficulty and cost of the ball tank body.

[0075] The shell 4.2 is also provided with an anti-corrosion layer 4.8 on the outside. The thickness of the anti-corrosion layer 4.8 is 6 mm to 12 mm and can be coated with glass fiber reinforced plastics to effectively prevent the shell 4.2 from being corroded by the soil.

[0076] See also Figure 3 The bottom of the buried ball storage tank 4 is provided with a drainage pipe, which is connected to the sump 6, and then the water is pumped out by the drainage pump 7 and discharged to other places on the ground. The buried ball storage tank 4 is provided with a manhole door 4.9 and a stairwell 8 outside. The operator can go down to the underground from the stairwell 8 and then enter the tank from the manhole door 4.9 for maintenance.

[0077] In this embodiment, the shell 4.2 is formed by sealing and welding the shell steel plates. The structure of the welding part is shown in FIG. Figure 4 , #1 shell splicing steel plate 4.2.1 is welded with #2 shell splicing steel plate 4.2.2 to form weld 4.2.4 between splicing steel plates, sealing channel steel 4.2.3 covers weld 4.2.4 between splicing steel plates and is welded with #1 shell splicing steel plate 4.2.1 and #2 shell splicing steel plate 4.2.2 respectively, and forms weld 4.2.5 between sealing channel steel and #1 shell splicing steel plate and weld 4.2.6 between sealing channel steel and #2 shell splicing steel plate, so as to seal weld 4.2.4 between splicing steel plates and reduce the probability of leakage or rupture of the spherical tank body. Sealing channel steel 4.2.3 can be selected from any one of [6.3, [8, [10, [12.6 and [14a].

[0078] The present invention adopts an underground type ball storage tank 4, the tank body is buried deep below the ground, and the soil pressure is used to offset part of the pressure of the gas in the tank body. The shell body is provided with reinforcing ribs arranged in a staggered manner in the horizontal and vertical directions, and the interior is provided with a central column 4.3 and a support rod 4.5 to assist the shell body in bearing a certain gas pressure, thereby reducing the wall thickness of the shell body and reducing the overall cost of the tank body.

[0079] This embodiment also provides an operating method of a compressed air energy storage system, which operates the compressed air energy storage system as described above, comprising the following steps:

[0080] Energy storage stage: the air compression unit compresses the air to generate high-pressure air, the cold water in the #1 cold storage tank 3.3 flows into the four-stage heat exchanger 1.12 to recover the heat in the high-pressure air to generate hot water stored in the #1 heat storage tank 3.1, and the cooled high-pressure air is output to the buried spherical storage tank 4; the cold water in the #2 cold storage tank 3.4 flows into the first-stage heat exchanger 1.6, the second-stage heat exchanger 1.8 and the third-stage heat exchanger 1.10 respectively to recover the heat in the high-pressure air to generate hot water stored in the #2 heat storage tank 3.2.

[0081] Energy release stage: the hot water in the #1 heat storage tank 3.1 flows into the first-stage heater 2.5 to heat the air, and the hot water after heat exchange cooling is output to the #1 cold storage tank 3.3; the hot water in the #2 heat storage tank 3.2 respectively enters the second-stage heater 2.6, the third-stage heater 2.7 and the fourth-stage heater 2.8 to heat the air, and then enters the #2 cold storage tank 3.4 after heat exchange cooling; the air expansion unit expands the heated high-pressure air and generates electricity through the generator 2.9.

[0082] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A compressed air energy storage system, characterized in that: include: An energy storage assembly (1), the energy storage assembly (1) comprising an air compression unit, a multi-stage heat exchanger and a multi-stage cooler, the air compression unit being connected to the multi-stage heat exchanger and the multi-stage cooler, the multi-stage heat exchanger and the multi-stage cooler being arranged in series along the flow direction of compressed air; An energy release component (2), the energy release component (2) comprising an air expansion unit and a multi-stage heater, the air expansion unit being connected to the multi-stage heater; A plurality of heat exchange medium storage tank groups (3), wherein the heat exchange medium storage tank groups (3) include at least one cold storage tank and at least one heat storage tank; the plurality of heat exchange medium storage tank groups (3) are respectively connected to the multi-stage heat exchanger and the multi-stage heater; A buried ball storage tank (4) is provided below the ground, the input end of the buried ball storage tank (4) is connected to an air compression unit, and the output end of the buried ball storage tank (4) is connected to an air expansion unit.

2. A compressed air energy storage system according to claim 1, characterized in that: At least one heat exchange medium storage tank group (3) is connected to the heat exchanger at the end of the air compression unit and the heater at the head end of the air expansion unit; The output end of the cold storage tank is connected to the input end of the heat exchanger, and the input end of the cold storage tank is connected to the output end of the heater; The input end of the heat storage tank is connected to the output end of the heat exchanger, and the output end of the heat storage tank is connected to the input end of the heater; A pressure balancing pipe is provided between the cold storage tank and the heat storage tank of each heat exchange medium storage tank group (3).

3. A compressed air energy storage system according to claim 1, characterized in that: The air compression unit comprises a multi-stage air compressor arranged in series, wherein the air inlet end of the first-stage air compressor is connected to the atmosphere, and the air outlet end of the last-stage air compressor is connected to the input end of the buried ball storage tank (4); the air inlet end of the first-stage air compressor is provided with an air filter; The air expansion unit comprises a multi-stage air expander arranged in series, wherein the air inlet end of the first-stage air expander is connected to the output end of the buried ball storage tank (4), and the air outlet end of the last-stage air expander is connected to the atmosphere; The air outlet end of each stage of the air compressor is connected to at least one set of heat exchangers and coolers, and the air inlet end of each stage of the air expander is connected to at least one set of heaters.

4. A compressed air energy storage system according to claim 1, characterized in that: The buried ball storage tank (4) is arranged at a depth of h underground, so that Ph≈(P1+P2) / 2, wherein Ph is the soil pressure outside the buried ball storage tank (4), Ph=soil density*9.8*h, P1 is the pressure after the buried ball storage tank (4) outputs compressed air, and P2 is the pressure after the buried ball storage tank (4) inputs compressed air.

5. A compressed air energy storage system according to claim 1, characterized in that: The buried ball storage spherical tank (4) comprises a spherical tank body and a support seat (4.1), wherein the spherical tank body is arranged on the support seat (4.1); the spherical tank body comprises a shell (4.2) and an inner support assembly, wherein the inner support assembly is supported inside the shell (4.2).

6. A compressed air energy storage system according to claim 5, characterized in that: The inner support assembly comprises a central column (4.3), a rib plate (4.4), a plurality of support rods (4.5) and a plurality of pads (4.6); both ends of the central column (4.3) are connected to the shell (4.2) via the pads (4.6); the plurality of support rods (4.5) are connected to the central column (4.3) via the rib plates (4.4); and the plurality of support rods (4.5) are connected to the shell (4.2) via the pads (4.6).

7. A compressed air energy storage system according to claim 6, characterized in that: The plurality of support rods (4.5) are symmetrically distributed and the angles α between two adjacent support rods (4.5) are equal; The angle α can be any one of 90°, 60°, 45°, 36° and 30°.

8. A compressed air energy storage system according to claim 5, characterized in that: The shell (4.2) is provided with a plurality of reinforcing ribs (4.7) arranged in an alternating manner on the outside, and the distance between two adjacent reinforcing ribs (4.7) on the spherical surface is 700 mm to 1000 mm; An anti-corrosion layer (4.8) is also provided on the outside of the shell (4.2), and the thickness of the anti-corrosion layer (4.8) is 6 mm to 12 mm.

9. A compressed air energy storage system according to any one of claims 1 to 8, characterized in that: It also includes a cooling system (5), which includes a cooling tower connected to the multi-stage cooler.

10. A method for operating a compressed air energy storage system, characterized in that: The operation of the compressed air energy storage system according to claim 9 comprises the following steps: Energy storage stage: the air compression unit compresses the air to generate high-pressure air, the cold water medium in the cold storage tank flows into the multi-stage heat exchanger to recover the heat in the air to generate hot water and store it in the heat storage tank, and the cooled high-pressure air is output to the buried spherical storage tank (4); Energy release stage: the air expansion unit expands the high-pressure air output by the buried spherical storage tank (4), the hot water medium in the heat storage tank flows into the multi-stage heater to heat the high-pressure air output by the buried spherical storage tank (4) and the air expanded by the air expansion unit, and the hot water medium after heat exchange cooling is output to the cold storage tank.

Images