Hydraulic compression energy storage system based on multi-working fluid staging and operating method

Abstract

The application discloses a kind of based on multi-working substance grading hydraulic compression energy storage system and operating method, system includes driving device, one end of driving device is connected with reservoir, the other end is connected with gas storage device, the gas storage device is connected with water pump by first pipeline, the water pump is connected with water storage device by second pipeline;The gas storage device includes first gas storage piece, second gas storage piece and third gas storage piece, first working substance is arranged in the first gas storage piece, second working substance is arranged in the second gas storage piece, third working substance is arranged in the third gas storage piece.By dividing into multiple stages, and allocating different organic working substance for each level of hydraulic compression system, the energy storage density of the energy storage system can be improved, the volume of the gas storage tank is reduced, and the equipment cost is reduced, solving the technical defects of high energy storage cost and low energy storage density of the existing compressed air energy storage system.

Description

Technical Field

[0001] This invention belongs to the field of hydraulic compression energy storage technology, specifically relating to a hydraulic compression energy storage system and its operation method based on multi-working-medium stage. Background Technology

[0002] Compressed air energy storage (CASS) is an energy storage system based on gas turbine technology. This system utilizes off-peak electricity to compress and store air in a storage chamber, converting electrical energy into the internal energy of the air. During peak electricity demand, the high-pressure air is released from the storage chamber and enters the gas turbine combustion chamber to burn with fuel, thereby driving the turbine to generate electricity. However, CASS requires a large footprint and has specific geographical requirements for the location of the storage chamber.

[0003] Currently, to address the issue of high geographical location requirements for compressed air energy storage, a technology using liquid pistons to compress air has emerged, employing water as the medium. However, the pressure resistance of these liquid pistons is designed based on the maximum gas pressure required for compression. When the liquid piston capacity is large, it increases construction costs. When the volume of gas being processed is relatively small, or when only the gas needs to be compressed to a lower pressure, it creates redundancy in the capacity and pressure resistance of the liquid piston, increasing operating costs and resulting in high energy storage costs and low energy density. Summary of the Invention

[0004] This invention provides a hydraulic compression energy storage system and its operation method based on multi-working-medium staged operation, in order to solve the technical defects of existing compressed air energy storage systems, such as high energy storage cost and low energy storage density.

[0005] To achieve the above objectives, the present invention employs the following technical solution:

[0006] In a first aspect, a multi-working-medium graded hydraulic compression energy storage system is provided, including a driving device. One end of the driving device is connected to a water storage tank, and the other end is connected to a gas storage device. The gas storage device is connected to a water pump through a first pipeline, and the water pump is connected to a water storage device through a second pipeline. The gas storage device includes a first gas storage component, a second gas storage component, and a third gas storage component. The first gas storage component contains a first working fluid, the second gas storage component contains a second working fluid, and the third gas storage component contains a third working fluid.

[0007] Furthermore, the first working medium is tetrafluoroethane, the second working medium is difluoromethane, and the third working medium is trifluoromethane.

[0008] Furthermore, the driving device includes an electric motor and a water pump, the water pump being mounted on the driving end of the electric motor, one end of the water pump being connected to a water storage tank, and the other end being connected to a gas storage device.

[0009] Furthermore, the drive device also includes a generator and a water turbine, with the generator connected to one end of the water turbine and the other end of the water turbine connected to a water storage tank and a gas storage device, respectively.

[0010] Furthermore, the first gas storage device, the second gas storage device, and the third gas storage device have the same structure.

[0011] Furthermore, the first gas storage component, the second gas storage component, and the third gas storage component are all gas storage tanks.

[0012] Furthermore, the operating pressure of the first gas storage device is 0.4~1.4 MPa.

[0013] Furthermore, the operating pressure of the second gas storage device is 1.4~3.4 MPa.

[0014] Furthermore, the operating pressure of the third gas storage device is 3.4~4.4 MPa.

[0015] Secondly, a method for operating a multi-working-medium staged hydraulic compression energy storage system is provided, the method employing the energy storage system described above, including:

[0016] The operating pressure of the gas storage components is preset, wherein the operating pressure of the first gas storage component is preset to 0.4~1.4 MPa, the operating pressure of the second gas storage component is preset to 1.4~3.4 MPa, and the operating pressure of the third gas storage component is preset to 3.4~4.4 MPa.

[0017] According to the preset operating pressure of the gas storage device, during the off-peak period of electricity consumption, the water working medium in the water storage tank is transported to the first gas storage device, the second gas storage device and the third gas storage device respectively by the driving device, the working medium in the first gas storage device, the second gas storage device and the third gas storage device is compressed and the heat is stored.

[0018] According to the preset operating pressure of the gas storage device, during peak electricity consumption periods, the working fluid in the first, second, and third gas storage devices is heated by the water storage device, causing it to vaporize and expand, driving the water flow to drive the generator to generate electricity; when the heat of the water storage device is insufficient, it can also be supplemented by an external heat source.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] 1. The system is equipped with three gas storage units, each containing a different working fluid. By dividing the hydraulic compression into multiple stages and allocating different organic working fluids to each stage of the hydraulic compression system, the energy storage density of the energy storage system can be increased, the volume of the gas storage tank can be reduced, and the equipment cost can be reduced. Furthermore, the different organic working fluids have different compression temperatures, and the heat of compression during the compression process can be utilized by each other, which improves the energy utilization efficiency of the system and solves the technical defects of existing compressed air energy storage systems, such as high energy storage cost and low energy storage density.

[0021] 2. Tetrafluoroethane is a non-ozone-depleting substance, and compared to traditional difluorochloromethane, it has a smaller negative impact on the environment. In addition, it has good chemical stability and is not prone to reacting with other materials, thus extending the service life of the system. Difluoromethane has a high energy efficiency ratio, consuming less energy for the same cooling capacity. Trifluoromethane also has a high energy efficiency ratio and is suitable for applications requiring high-efficiency cooling.

[0022] 3. The electric motor directly drives the water pump, realizing the integration of the equipment, reducing energy loss during the energy conversion process, improving overall efficiency, and reducing maintenance costs and failure rate; secondly, the water pump draws water from the water storage tank, ensuring a stable water supply, which is crucial for the normal operation of the gas storage device.

[0023] 4. The water turbine uses water flow to generate power, which in turn drives the generator to produce electricity, enabling the system to achieve energy self-sufficiency to a certain extent and reducing dependence on external power sources. Furthermore, in the event of an external power failure or outage, the water turbine and generator can provide backup power to the system, enhancing its stability and reliability.

[0024] 5. Since the first, second, and third gas storage components have the same structure, these gas storage components can be replaced with each other when needed, without worrying about compatibility issues, thus reducing the system's maintenance costs.

[0025] 6. Using the same gas storage tank can ensure that the system maintains stable performance throughout its entire life cycle. Attached Figure Description

[0026] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 A schematic diagram of the structure of the hydraulic compression energy storage system based on multi-working-medium stage provided by the present invention;

[0028] Figure 2 A flowchart of the operation method of a hydraulic compression energy storage system based on multi-working-medium stage provided by the present invention;

[0029] In the diagram: 1. First gas storage unit; 2. Second gas storage unit; 3. Third gas storage unit; 4. Electric motor; 5. Water pump; 6. Water storage tank; 7. Water pump; 8. Water storage device. Detailed Implementation

[0030] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0031] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0032] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0033] In the description of the embodiments of the present invention, it should be noted that if terms such as "upper," "lower," "horizontal," or "inner" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of the invention is in use, they 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, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention. Furthermore, terms such as "first" and "second" are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0034] Furthermore, the use of the term "horizontal" does not imply that the component must be absolutely horizontal, but rather that it can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal than "vertical," and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0035] In the description of the embodiments of the present invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in the present invention according to the specific circumstances.

[0036] Compressed air energy storage is an energy storage system based on gas turbine technology. This system uses off-peak electricity to compress air and store it in an air storage chamber, converting electrical energy into the internal energy of the air. During peak electricity demand, the high-pressure air is released from the air storage chamber and enters the combustion chamber of the gas turbine to burn together with fuel, thereby driving the turbine to generate electricity.

[0037] Currently, commonly used compressed air energy storage technology utilizes water turbines for power generation and energy storage. This process employs liquid pistons, using water as a medium to compress air, thus solving problems related to regulation, efficiency, and container lifespan caused by drastic pressure changes during air compression. However, the pressure resistance of these liquid pistons is designed based on the maximum gas pressure to be compressed. When the liquid piston capacity is large, it increases construction costs. When the volume of gas to be processed is relatively small, or when only the gas needs to be compressed to a lower pressure, it creates redundancy in the capacity and pressure resistance of the liquid piston, increasing operating costs and resulting in high energy storage costs and low energy density.

[0038] In order to address the technical shortcomings of existing compressed air energy storage systems, such as high energy storage cost and low energy storage density, the inventors have provided a hydraulic compression energy storage system based on multi-working-medium stages and its operation method.

[0039] The present invention will now be described in further detail with reference to the accompanying drawings:

[0040] In a first aspect, embodiments of the present invention provide a hydraulic compression energy storage system based on multi-working-medium staged operation, such as... Figure 1As shown, the system includes a drive unit, one end of which is connected to a water storage tank 6, and the other end is connected to a gas storage device. The drive unit pumps the working fluid from the water storage tank 6 into the gas storage device. The gas storage device is connected to a water pump 7 via a first pipeline, and the water pump 7 is connected to a water storage device 8 via a second pipeline. The gas storage device includes a first gas storage component 1, a second gas storage component 2, and a third gas storage component 3. The first gas storage component 1 contains a first working fluid, the second gas storage component 2 contains a second working fluid, and the third gas storage component 3 contains a third working fluid. The drive unit pumps the working fluid from the water storage tank 6 into the first gas storage component 1, the second gas storage component 2, and the third gas storage component 3, respectively, and compresses and stores the first, second, and third working fluids in each component. Before the system operates, the operating pressures of the first gas storage unit 1, the second gas storage unit 2, and the third gas storage unit 3 are preset. The operating pressure of the first gas storage unit 1 is preset to 0.4~1.4 MPa, the operating pressure of the second gas storage unit 2 is preset to 1.4~3.4 MPa, and the operating pressure of the third gas storage unit 3 is preset to 3.4~4.4 MPa. After the presets are completed, during off-peak electricity periods, according to the pressure operating range of different gas storage tanks, the water working medium in the water storage tank 6 is sequentially pumped to the first gas storage unit 1, the second gas storage unit 2, and the third gas storage unit 3 using a drive device to compress the first, second, and third working media in the first, second, and third gas storage units 1 and 3. In this embodiment, the first working medium is preferably tetrafluoroethane. Tetrafluoroethane is a non-ozone-depleting substance and has a smaller negative impact on the environment compared to traditional dichlorofluoromethane. Furthermore, it has good... The first working medium is chemically stable and does not easily react with other materials, thus extending the system's service life. The second working medium is preferably difluoromethane, which has a high energy efficiency ratio, consuming less energy for the same cooling capacity. The third working medium is preferably trifluoromethane, which also has a high energy efficiency ratio and is suitable for applications requiring high-efficiency refrigeration. During compression, the specific compression sequence is as follows: first, the tetrafluoroethane working medium in the first gas storage unit 1 is compressed; then, the difluoromethane in the second gas storage unit 2 is compressed; and finally, the trifluoromethane in the third gas storage unit 3 is compressed. During the compression of tetrafluoroethane, difluoromethane, and trifluoromethane in the first, second, and third gas storage units 1 and 2, water pump 7 is activated to recover the heat generated during compression using circulating water, storing the heat in the water storage device 8 to achieve energy storage.During peak electricity consumption periods, the water medium in the water storage device 8 is first heated. It is worth noting that the heat source during the heating process can be water, air, or flue gas, depending on the operational needs and conditions. This embodiment is not limited to this. The preferred heating temperature is around 55 ℃. After heating, the heated water medium is used to heat the liquid phases of tetrafluoroethane, difluoromethane, and trifluoromethane in the first gas storage device 1, the second gas storage device 2, and the third gas storage device 3. The specific heating sequence is as follows: first, the trifluoromethane in the third gas storage device 3 is heated; then, the difluoromethane in the second gas storage device 2 is heated; and finally, the tetrafluoroethane in the first gas storage device 1 is heated. This causes the liquid phases of tetrafluoroethane, difluoromethane, and trifluoromethane to vaporize. The vaporized tetrafluoroethane, difluoromethane, and trifluoromethane then push the water medium in the corresponding gas storage device, causing the water medium to drive the drive device to generate electricity. During operation, the system is equipped with three gas storage units, each containing a different working fluid. By dividing the hydraulic compression into multiple stages and allocating different organic working fluids to each stage of the hydraulic compression system, the energy storage density of the energy storage system can be increased, the volume of the gas storage tank can be reduced, and the equipment cost can be reduced. Furthermore, the different temperatures during the compression process of different organic working fluids allow for mutual utilization of the heat of compression, thereby improving the energy utilization efficiency of the system and solving the technical defects of existing compressed air energy storage systems, such as high energy storage cost and low energy storage density.

[0041] In one embodiment, the driving device includes an electric motor 4 and a water pump 5. The water pump 5 is mounted on the drive end of the electric motor 4, with one end connected to a water storage tank 6 and the other end connected to a gas storage device. The electric motor 4 directly drives the water pump 5, achieving equipment integration, reducing energy losses during conversion, improving overall efficiency, and lowering maintenance costs and failure rates. Furthermore, the water pump 5 draws water from the water storage tank 6, ensuring a stable water supply, which is crucial for the normal operation of the gas storage device. In another embodiment, the driving device also includes a generator and a water turbine. The generator is connected to one end of the water turbine, and the other end of the water turbine is connected to both the water storage tank 6 and the gas storage device. During the power generation process, the water medium can drive the water turbine to rotate and generate electricity.

[0042] In this embodiment, the first gas storage component 1, the second gas storage component 2, and the third gas storage component 3 have identical structures, and all three are gas storage tanks. Because these components have the same structure, they can be interchanged when needed without compatibility issues, reducing system maintenance costs. Furthermore, using identical gas storage tanks ensures stable system performance throughout its entire lifespan.

[0043] Secondly, this embodiment provides an operation method for a multi-working-medium staged hydraulic compression energy storage system. The method employs the energy storage system described above. Figure 2 As shown, it includes:

[0044] S101. Preset the operating pressure of the gas storage components, wherein the operating pressure of the first gas storage component is preset to 0.4~1.4 MPa, the operating pressure of the second gas storage component is preset to 1.4~3.4 MPa, and the operating pressure of the third gas storage component is preset to 3.4~4.4 MPa; for example, before the system is put into operation, the operating pressures of the first gas storage component 1, the second gas storage component 2, and the third gas storage component 3 are preset, wherein the operating pressure of the first gas storage component 1 is preset to 0.4~1.4 MPa, the operating pressure of the second gas storage component 2 is preset to 1.4~3.4 MPa, and the operating pressure of the third gas storage component 3 is preset to 3.4~4.4 MPa.

[0045] S102. According to the preset operating pressure of the gas storage components, during off-peak electricity periods, the driving device is used to transport the working medium in the water storage tank to the first, second, and third gas storage components respectively, compressing the working medium in the first, second, and third gas storage components and storing heat; exemplarily, after the preset is completed, during off-peak electricity periods, the driving device is used to pump the working medium in the water storage tank 6 to the first, second, and third gas storage components 1, 2, and 3, compressing the first, second, and third working media in the first, second, and third gas storage components 1, 2, and 3; in this embodiment, the first working media is preferably tetrafluoroethane. The first working fluid is tetrafluoroethane, a non-ozone-depleting substance. Compared to traditional difluorochloromethane, it has a smaller negative impact on the environment and exhibits good chemical stability, making it less prone to reacting with other materials, thus extending the system's lifespan. The second working fluid is preferably difluoromethane, which has a high energy efficiency ratio, consuming less energy for the same cooling capacity. The third working fluid is preferably trifluoromethane, which also has a high energy efficiency ratio and is suitable for applications requiring high-efficiency cooling. During compression, the specific compression sequence is as follows: first, the tetrafluoroethane working fluid in the first gas storage unit 1 is compressed; then, the difluoromethane in the second gas storage unit 2 is compressed; and finally, the trifluoromethane in the third gas storage unit 3 is compressed. During the compression of tetrafluoroethane, difluoromethane, and trifluoromethane in the first, second, and third gas storage units 1 and 2, water pump 7 is activated to recover the heat generated during compression using circulating water. This heat is stored in the water storage device 8, thus achieving energy storage.

[0046] S103. According to the preset operating pressure of the gas storage device, during peak electricity consumption periods, the working fluid in the first, second, and third gas storage devices is heated using a water storage device, causing it to vaporize and expand, driving water flow and powering the drive device to generate electricity. When the heat of the water storage device is insufficient, it can also be supplemented by an external heat source. For example, during peak electricity consumption periods, the water working fluid in the water storage device 8 is heated first. It is worth noting that the heat source during the heating process can be water, air, or flue gas, allowing the use of different heat sources (water, air, flue gas) to make the system more flexible and adaptable. This not only reduces dependence on specific energy sources but also provides cost-effectiveness when energy prices fluctuate. For example, during peak electricity consumption periods, the power supply may be tight. By using non-electric heat sources (such as water and air) for heating, the load on the power grid can be reduced, and the stability and reliability of the power system can be improved. In specific operations, a suitable heat source can be selected according to the operational needs and working conditions to maximize energy utilization efficiency; this embodiment is not limited to this. The preferred heating temperature is around 55 ℃. After heating, the heated water medium is used to heat the liquid phase tetrafluoroethane, difluoromethane, and trifluoromethane in the first gas storage unit 1, the second gas storage unit 2, and the third gas storage unit 3. The specific heating sequence is to first heat the trifluoromethane in the third gas storage unit 3, then heat the difluoromethane in the second gas storage unit 2, and finally heat the tetrafluoroethane in the first gas storage unit 1, causing the liquid phase tetrafluoroethane, difluoromethane, and trifluoromethane to vaporize. The vaporized tetrafluoroethane, difluoromethane, and trifluoromethane then push the water medium in the corresponding gas storage unit, causing the water medium to drive the drive device to generate electricity. During the process of the drive device generating electricity, the water medium can drive the water turbine to rotate and generate electricity. During operation, the system employs three gas storage units, each containing a different working fluid. Due to the varying physical and chemical properties of these working fluids, compression efficiency is maintained while further reducing the volume of the storage tanks, thus lowering the equipment's footprint and manufacturing costs. Secondly, by dividing the hydraulic compression into multiple stages and allocating different organic working fluids to each stage, the compression process at each stage becomes more efficient, increasing the energy storage density of the system, reducing tank volume, and lowering equipment costs. Furthermore, the different temperatures during the compression processes of the various organic working fluids allow the heat generated during high-temperature compression to be used to preheat or heat the low-temperature working fluid to be compressed, recovering heat that would otherwise be wasted and improving the overall energy recovery rate of the system. This addresses the technical shortcomings of existing compressed air energy storage systems, such as high storage costs and low energy density. Additionally, the mutual utilization of compression heat reduces the system's reliance on external heat sources or cooling equipment, thereby lowering energy consumption. This not only reduces energy consumption but also lowers operating costs.

[0047] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit its scope of protection. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that after reading the present invention, they can still make various changes, modifications or equivalent substitutions to the specific implementation of the invention, but these changes, modifications or equivalent substitutions are all within the scope of protection of the pending claims of the invention.

Claims

1. A multi-working fluid staged based hydro-compression energy storage system, characterized in that, The device includes a drive unit, one end of which is connected to a water storage tank (6) and the other end is connected to a gas storage device. The gas storage device is connected to a water pump (7) through a first pipeline and the water pump (7) is connected to a water storage device (8) through a second pipeline. The gas storage device includes a first gas storage component (1), a second gas storage component (2), and a third gas storage component (3). The first gas storage component (1) contains a first working fluid, the second gas storage component (2) contains a second working fluid, and the third gas storage component (3) contains a third working fluid. The first working medium is tetrafluoroethane, the second working medium is difluoromethane, and the third working medium is trifluoromethane; The first gas storage unit (1) operates at a pressure of 0.4~1.4 MPa; The operating pressure of the second gas storage unit (2) is 1.4~3.4 MPa; The operating pressure of the third gas storage unit (3) is 3.4~4.4 MPa.

2. The energy storage system of claim 1, wherein, The driving device includes an electric motor (4) and a water pump (5). The water pump (5) is located on the driving end of the electric motor (4). One end of the water pump (5) is connected to the water storage tank (6), and the other end is connected to the gas storage device.

3. The energy storage system of claim 1, wherein, The drive device also includes a generator and a water turbine. The generator is connected to one end of the water turbine, and the other end of the water turbine is connected to a water storage tank (6) and a gas storage device, respectively.

4. The energy storage system of claim 1, wherein, The first gas storage device (1), the second gas storage device (2), and the third gas storage device (3) have the same structure.

5. The energy storage system according to claim 1 or 4, characterized in that, The first gas storage component (1), the second gas storage component (2) and the third gas storage component (3) are all gas storage tanks.

6. A method for operating a multi-working-medium staged hydraulic compression energy storage system, characterized in that, The method is performed using the energy storage system according to any one of claims 1-5, and includes: The operating pressure of the gas storage components is preset, wherein the operating pressure of the first gas storage component is preset to 0.4~1.4 MPa, the operating pressure of the second gas storage component is preset to 1.4~3.4 MPa, and the operating pressure of the third gas storage component is preset to 3.4~4.4 MPa. According to the preset operating pressure of the gas storage device, during the off-peak period of electricity consumption, the water working medium in the water storage tank is transported to the first gas storage device, the second gas storage device and the third gas storage device respectively by the driving device, the working medium in the first gas storage device, the second gas storage device and the third gas storage device is compressed and the heat is stored. According to the preset operating pressure of the gas storage device, during peak electricity consumption periods, the working fluid in the first, second, and third gas storage devices is heated by the water storage device, causing it to vaporize and expand, driving the water flow to drive the generator to generate electricity; when the heat of the water storage device is insufficient, it can also be supplemented by an external heat source.

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