Compressed air energy storage system capable of low energy first charge and method of first charge thereof

Abstract

This invention provides a compressed air energy storage system and its initial injection method that enable low-energy initial injection, addressing the technical problems of high initial injection cost, long injection time, and low efficiency in existing technologies. The compressed air energy storage system connects the outlet points of the vent pipes corresponding to the compressor units (excluding the initial compressor unit) to the inlet of their respective compressor units. A first shut-off valve is added at the vent pipe's connection to the vent silencer, and an injection valve is added at the vent pipe's connection to the air storage device. This invention also provides an initial injection method based on this compressed air energy storage system, which offers low injection cost and significantly shortens the initial injection time.

Description

Technical Field

[0001] This invention relates to compressed air energy storage systems, and more particularly to a compressed air energy storage system and its initial injection method that enables low-energy-consumption initial air injection. Background Technology

[0002] Compressed air energy storage, as a type of large-scale grid-scale energy storage, is considered one of the most promising technologies for the future, characterized by its long lifespan, low cost, high efficiency, and environmental friendliness. The main components of a compressed air energy storage system include a compressor unit, an air storage chamber (salt cavern, pipeline steel, artificial chamber), an air turbine expander, a generator, and heat exchange facilities.

[0003] In the energy storage phase, the compressed air energy storage system uses electricity generated from intermittent renewable energy sources or surplus off-peak electricity from the power grid at night to drive a compressor to compress air and store the electricity in the air storage chamber as high-pressure air. In the energy release phase, the high-pressure air enters the combustion chamber and mixes with gaseous fuel for combustion. The resulting high-pressure, high-temperature gas drives a gas turbine to rotate and do work, or the high-pressure air is reheated and enters a turbine expander to rotate and do work, driving a generator to generate electricity and connect to the grid.

[0004] The commonly used technology in the current field is the salt cavern gas injection and brine discharge process. This process involves injecting air into underground salt caverns using a positive displacement compressor to discharge the buried brine, completing the initial gas filling process for salt cavern gas storage. However, this process requires a separate positive displacement compressor, independent of the existing compressed air energy storage system, resulting in high costs. Furthermore, due to the low flow rate of the positive displacement compressor, the initial gas filling process for a 100MW-level compressed air energy storage project using this method would last for several months, resulting in a long filling time and low efficiency. Summary of the Invention

[0005] The purpose of this invention is to provide a compressed air energy storage system and its initial injection method that can achieve low-energy consumption initial injection, in order to solve the technical problems of high initial injection cost, long injection time and low efficiency in the prior art.

[0006] To achieve the above objectives, the technical solution of the present invention is as follows:

[0007] A compressed air energy storage system that enables low-energy initial air injection, characterized by:

[0008] It includes multiple compressor units connected in series, multiple heat exchange separation units corresponding to each compressor unit, multiple anti-surge pipes, multiple vent pipes, and a vent silencer and gas storage device.

[0009] Each heat exchange separation unit is located between the outlet end of the corresponding compressor unit and the inlet end of the next compressor unit. The outlet end of the heat exchange separation unit of the last compressor unit is connected to the gas storage device.

[0010] The multiple anti-surge pipes and multiple vent pipes correspond one-to-one with multiple compressor units, and each pipe is equipped with a corresponding control valve to control the opening and closing of each channel. Among them, the anti-surge pipe and vent pipe corresponding to the first compressor unit are the same pipe, and their two ends are connected to the outlet end of the first compressor unit and the vent silencer, respectively. The anti-surge pipes corresponding to the other compressor units are connected to the outlet end of the preceding compressor unit and the outlet end of the corresponding compressor unit, respectively. The inlet end of the vent pipes corresponding to the other compressor units is connected to the inlet end of the corresponding compressor unit, and the outlet end is divided into two paths. One path is connected to the vent silencer and is equipped with a first shut-off valve, and the other path is connected to the gas storage device and is equipped with a gas injection valve.

[0011] In the multi-stage compressor unit, a process venting pipe is provided between the heat exchange separation unit and the venting silencer corresponding to the last stage compressor unit.

[0012] The gas storage device is equipped with a second shut-off valve and a third shut-off valve at its inlet. The second shut-off valve is located at the outlet of the heat exchange separation unit corresponding to the final stage compressor unit and is used to open or shut off the gas passage compressed by the final stage compressor unit. The third shut-off valve is located at the inlet of the gas storage device and is used to adjust the gas pressure entering the gas storage device.

[0013] Furthermore, the gas storage device is an artificial chamber or a pipeline steel.

[0014] Furthermore, in the multi-stage compressor unit, the inlet end of the first stage compressor unit is sequentially provided with an air filter and an intake muffler; the air filter is used to filter impurities in the inlet air; the intake muffler is located between the air filter and the inlet end of the first stage compressor unit and is used to eliminate noise generated by the inlet air.

[0015] Furthermore, the heat exchange and separation unit includes a heat exchanger and a separator connected in sequence, wherein the heat exchanger is located near the outlet end of the corresponding compressor unit and is used to reduce the temperature of the compressed gas; the separator is used to separate the compressed gas into gas and liquid.

[0016] Furthermore, each compressor unit is equipped with an outlet check valve between its outlet end and the inlet end of the corresponding heat exchanger; the inlet end of the anti-surge pipeline corresponding to the first compressor unit is located between the outlet end of the first compressor unit and the outlet check valve corresponding to the first compressor unit; the inlet end of the anti-surge pipeline corresponding to the remaining compressor units is located between the outlet end of the corresponding compressor unit and the corresponding outlet check valve, and the outlet end is located between the outlet check valve corresponding to the previous compressor unit and the heat exchanger.

[0017] The process vent pipe is located between the heat exchanger and the vent silencer corresponding to the last-stage compressor unit.

[0018] Furthermore, except for the first compressor unit, the inlets of the vent pipes corresponding to the other compressor units are located between the gas outlet end of the separator corresponding to the previous stage compressor unit and the inlet end of the corresponding compressor unit.

[0019] Furthermore, the second and third shut-off valves are electrically operated shut-off valves or pneumatic shut-off valves.

[0020] Meanwhile, the present invention also provides a method for the initial injection of compressed air into a compressed air energy storage system that enables low-energy initial injection, characterized by the following steps:

[0021] S1, Gas injection into the first stage compressor unit

[0022] 1.1 Gradually open the guide vanes or stator vanes of each compressor unit and the corresponding anti-surge pipes. Close the vent pipes of the compressor units other than the first compressor unit and the process vent pipes. Open the gas injection valves on the vent pipes of the second compressor unit and close the gas injection valves on the other vent pipes. Close the first and second shut-off valves and open the third shut-off valve.

[0023] 1.2 Start the first compressor unit and switch to the power frequency operation mode, while the other compressor units are in a non-operating, stationary state;

[0024] 1.3 Gradually close the anti-surge pipe corresponding to the first stage compressor unit until it is completely closed, and at the same time, gradually open the vent pipe corresponding to the second stage compressor unit until it is fully open;

[0025] 1.4 When the first stage compressor unit reaches its maximum discharge pressure, the compressed air enters the gas storage device through the corresponding vent pipe of the second stage compressor unit, so that the pressure in the gas storage device reaches the maximum discharge pressure of the first stage compressor unit.

[0026] 1.5. The first stage compressor unit is shut down. The anti-surge pipe corresponding to the first stage compressor unit is opened. The air injection valve on the vent pipe corresponding to the second stage compressor unit is closed. The first shut-off valve on the vent pipe corresponding to the second stage compressor unit is opened. The pressure in the air storage device is checked to see if it has reached its initial set pressure target value. If so, the first air injection of the compressed air energy storage system is completed. If not, the procedure in step S2 is followed.

[0027] S2, gas injection from the first stage + second stage compressor unit.

[0028] 2.1 Based on step 1.5, close the vent pipe corresponding to the second-stage compressor unit and open the gas injection valve on the vent pipe corresponding to the third-stage compressor unit;

[0029] 2.2 Start the first stage compressor unit. The other compressor units are in a non-operating, stationary state. After the first stage compressor unit switches to the power frequency operation mode, start to slowly close the anti-surge pipeline corresponding to the first stage compressor unit. Stop closing after the compressor is out of the blockage area and wait for the second stage compressor unit to start.

[0030] 2.3 Start the second-stage compressor unit. After the second-stage compressor unit switches to the power frequency operation mode, slowly close the anti-surge pipeline corresponding to the second-stage compressor unit.

[0031] 2.4. Continuously and slowly alternately close the anti-surge pipes corresponding to the first stage compressor unit and the second stage compressor unit until they are completely closed. At the same time, slowly open the vent pipes corresponding to the third stage compressor unit until they are fully open.

[0032] 2.5 When the first-stage compressor unit and the second-stage compressor unit reach their maximum discharge pressure, the air enters the gas storage device through the corresponding vent pipe of the third-stage compressor unit, so that the pressure in the gas storage device reaches the maximum discharge pressure of the first-stage compressor unit and the second-stage compressor unit.

[0033] 2.6. The first and second stage compressor units are shut down. The anti-surge pipes corresponding to the first and second stage compressor units are opened. The air injection valve on the vent pipe corresponding to the third stage compressor unit is closed. The first shut-off valve on the vent pipe corresponding to the third stage compressor unit is opened. It is then determined whether the pressure in the air storage device has reached its initial set pressure target value. If yes, the first air injection of the compressed air energy storage system is completed; otherwise, the procedure in step S3 is followed.

[0034] S3. Perform air injection for the first compressor unit before the second or more compressor units according to the methods in steps 2.1 to 2.6 until the pressure in the air storage device reaches its initial set pressure target value, and the first air injection of the compressed air energy storage system is completed; if the pressure in the air storage device still does not reach its initial set pressure target value after the air injection of the first compressor unit before the last compressor unit is completed, then proceed according to the method in step S4.

[0035] S4, First stage + Second stage + ... + Final stage compressor unit gas injection

[0036] 4.1 Open the anti-surge pipes corresponding to each compressor unit, close the vent pipes corresponding to the other compressor units except the first compressor unit, and close the process vent pipes; open each first shut-off valve, close each gas injection valve, close the second shut-off valve, and open the third shut-off valve.

[0037] 4.2 Following steps 2.2 to 2.4, start each compressor unit in sequence. When starting the last compressor unit, slowly and alternately close the anti-surge pipelines corresponding to the first, second, ... last compressor units until they are all closed. At the same time, open the second shut-off valve.

[0038] 4.3 Air passes through the first stage, second stage... and final stage compressor units in sequence, and then enters the air storage device through the pipeline between the final stage compressor unit and the air storage device, thus completing the first air injection of the compressed air energy storage system.

[0039] Furthermore, in step 4.2, the driving method of the terminal compressor unit is a variable speed regulation method.

[0040] The present invention has the following beneficial effects:

[0041] 1. The compressed air energy storage system provided by this invention enables low-energy initial gas injection. It completes the process optimization and gas injection scheme design of large turbine compressor units under ultra-wide back pressure gas injection mode. It achieves a low-energy initial gas injection scheme with minimal modification and investment, and has low gas injection cost and high efficiency.

[0042] 2. The initial air injection method for the compressed air energy storage system provided by the present invention can greatly shorten the initial air injection time compared with the traditional air injection scheme of independent volumetric small compressor units.

[0043] 3. The initial air injection method of the compressed air energy storage system provided by the present invention saves more than 50% of electricity compared with the existing technology that does not optimize the pipeline and uses a separate air injection system for initial air injection, and is more environmentally friendly. Attached Figure Description

[0044] Figure 1 This is a schematic diagram of an embodiment of the compressed air energy storage system of the present invention, which enables low-energy initial air injection.

[0045] The attached figures are labeled as follows:

[0046] 1-Compressor unit, 2-Heat exchange and separation unit, 21-Heat exchanger, 22-Separator, 3-Anti-surge pipe, 4-Vent pipe, 5-Vent silencer, 6-Gas storage device, 7-First shut-off valve, 8-Injection valve, 9-Process vent pipe, 10-Second shut-off valve, 11-Third shut-off valve, 12-Air filter, 13-Intake silencer, 14-Outlet check valve. Detailed Implementation

[0047] The technical solution of the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0048] like Figure 1As shown, this embodiment provides a compressed air energy storage system that can achieve low-energy initial gas injection, including a multi-stage compressor unit 1 connected in series, a plurality of heat exchange separation units 2 corresponding one-to-one with the multi-stage compressor unit 1, a plurality of anti-surge pipes 3, a plurality of vent pipes 4, a vent silencer 5, and a gas storage device 6.

[0049] Each heat exchange separation unit 2 is located between the outlet end of the corresponding compressor unit 1 and the inlet end of the next compressor unit 1. The outlet end of the last compressor unit 1 corresponding to the heat exchange separation unit 2 is connected to the gas storage device 6.

[0050] The heat exchange and separation unit 2 includes a heat exchanger 21 and a separator 22 connected in sequence. The heat exchanger 21 is located near the outlet end of the corresponding compressor unit 1 and is used to reduce the temperature of the compressed gas. The separator 22 is used to separate the compressed gas into gas and liquid.

[0051] Multiple anti-surge pipes 3 and multiple vent pipes 4 correspond one-to-one with multiple compressor units 1, and each pipe is equipped with a control valve to control the opening and closing of the corresponding pipe. Among them, the anti-surge pipe 3 and vent pipe 4 corresponding to the first compressor unit 1 are the same pipe, and the two ends of the pipe are connected to the outlet end of the first compressor unit 1 and the vent silencer 5, respectively.

[0052] The anti-surge pipes 3 for the compressor units 1 other than the first compressor unit 1 are connected at both ends to the outlet end of the preceding compressor unit 1 and the outlet end of the corresponding compressor unit 1, respectively. The inlet ends of the vent pipes 4 for the compressor units 1 other than the first compressor unit 1 are located between the gas outlet end of the separator 22 corresponding to the preceding compressor unit 1 and the inlet end of the corresponding compressor unit 1. The outlet ends are divided into two paths, one of which is connected to the vent silencer 5 and is equipped with a first shut-off valve 7, and the other is connected to the gas storage device 6 and is equipped with a gas injection valve 8.

[0053] To improve system safety, each compressor unit 1 is equipped with an outlet check valve 14 between its outlet end and the inlet end of the corresponding heat exchanger 21. Specifically, the inlet end of the anti-surge pipe 3 corresponding to the first compressor unit 1 is located between the outlet end of the first compressor unit 1 and the corresponding outlet check valve 14; the inlet ends of the anti-surge pipes 3 corresponding to the remaining compressor units 1 are located between the outlet end of the corresponding compressor unit 1 and the corresponding outlet check valve 14, and the outlet ends are located between the outlet check valve 14 of the preceding compressor unit 1 and the heat exchanger 21.

[0054] In the multi-stage compressor unit 1, the inlet end of the first stage compressor unit 1 is provided with an air filter 12 and an intake muffler 13 respectively; the air filter 12 is used to filter impurities in the inlet air; the intake muffler 13 is located between the air filter 12 and the inlet end of the first stage compressor unit 1, and is used to eliminate the noise generated by the inlet air.

[0055] The gas storage device 6 is equipped with a second shut-off valve 10 and a third shut-off valve 11 at its inlet. The second shut-off valve 10 is located at the outlet of the heat exchange separation unit 2 corresponding to the final compressor unit 1, and is used to open or shut off the gas passage compressed by the final compressor unit 1. The third shut-off valve 11 is located at the inlet of the gas storage device 6 and is used to adjust the gas pressure entering the gas storage device 6. In this embodiment, the second shut-off valve 10 is an electrically operated shut-off valve, and the third shut-off valve 11 is a pneumatically operated shut-off valve.

[0056] The gas storage device 6 can be an artificial chamber, or a gas storage unit such as a pipeline steel or salt cavern, making the application of this system more flexible.

[0057] In the multi-stage compressor unit 1, a process venting pipe 9 is provided between the heat exchanger 21 and the venting silencer 5 corresponding to the last stage compressor unit 1, which is used to release pressure after the compressed air energy storage system is overpressurized.

[0058] This embodiment uses a compressed air energy storage system of a three-stage compressor unit as an example to illustrate its working process.

[0059] Compressor unit 1 draws in air from the atmosphere, which passes sequentially through air filter 12 and intake muffler 13 before entering the first-stage compressor unit 1 for pressurization. The compressed air then flows out of the outlet of the first-stage compressor unit 1 and passes sequentially through the outlet check valve 14, heat exchanger 21, and separator 22 before entering the second-stage compressor unit 1 for further pressurization. The compressed air then flows out of the outlet of the second-stage compressor unit 1 and passes sequentially through the outlet check valve 14, heat exchanger 21, and separator 22 before entering the third-stage compressor unit 1 for further pressurization. Finally, the compressed air flows out of the outlet of the third-stage compressor unit 1 and passes sequentially through the outlet check valve 14, heat exchanger 21, and separator 22 before entering the air storage device 6.

[0060] During the compression process, each compressor unit 1 typically has two stages of heat exchangers connected in series: a regenerative heat exchanger and a waste heat exchanger. A separator can also be installed between the two types of heat exchangers. The main purpose of the regenerative heat exchanger is to extract and store the high-temperature heat energy from the compressed air, while the purpose of the waste heat exchanger is to dissipate the low-grade heat that cannot be recovered and stored, thereby controlling the temperature of the air entering the next stage compressor to stabilize.

[0061] The core of this embodiment is to change the outlet points of the original two-stage vent valve and its vent pipe, and the three-stage vent valve and its vent pipe from the outlets of the two-stage and three-stage compressors to the inlets of the compressors. Shut-off valves are added to the two vent pipes leading to the vent silencer, and an additional pipe and injection valve are added to each of the main air charging pipes to the artificial chamber. Generally, depending on the heat storage temperature and the air storage pressure in the chamber, three-stage or four-stage compressor units are set up in series to achieve the high-pressure air injection requirements. Below, the initial air injection process of the compressed air energy storage system of the three-stage compressor unit 1 will be described in detail.

[0062] A method for initial gas injection of a compressed air energy storage system that enables low-energy initial gas injection includes the following steps:

[0063] S1, Gas injection into the first stage compressor unit

[0064] Before initial air injection, the air storage device 6 is at atmospheric pressure. The first-stage compressor unit 1 can complete the air filling process from atmospheric pressure to the maximum discharge pressure range designed for it. Before this, the number of stages of the compressor unit is estimated based on the preset upper limit of the pressure target of the air storage device 6 and the maximum discharge pressure range of the compressor unit, thus ensuring that the pressure of the air storage device 6 reaches its set target value. The specific air injection process of the first-stage compressor unit is as follows:

[0065] 1.1 Before starting the first stage compressor unit 1, the stator vanes of the axial compressor or the guide vanes of the centrifugal compressor are at their minimum operating angle. Open the anti-surge pipes 3 corresponding to each stage compressor unit 1 in sequence, close the vent pipes 4 corresponding to the other compressor units 1 (excluding the first stage compressor unit 1), and close the process vent pipes 9; open the injection valve 8 on the vent pipe 4 corresponding to the second stage compressor unit 1, and close the injection valves 8 corresponding to the other vent pipes 4; close each first shut-off valve 7 and second shut-off valve 10, and open the third shut-off valve 11.

[0066] 1.2 Start the first stage compressor unit 1. Driven by the main motor, the first stage compressor unit 1 completes the speed increase and switches to the power frequency operation mode. The other stages of compressor unit 1 are in a non-operating static state.

[0067] 1.3 Gradually open the guide vanes or stator vanes of the first-stage compressor unit 1 and gradually close the corresponding anti-surge pipe 3 until it is fully closed. As a result, the outlet pressure of the first-stage compressor unit 1 gradually increases and moves away from the blockage zone. At the same time, gradually open the corresponding vent pipe 4 of the second-stage compressor unit 1 until it is fully open. That is, when the corresponding vent pipe 4 of the second-stage compressor unit 1 is fully open, the corresponding anti-surge pipe 3 of the first-stage compressor unit 1 is fully closed.

[0068] 1.4 The axial compressor stator vanes or centrifugal compressor guide vanes of the first stage compressor unit 1 gradually open from the minimum operating angle to full opening. At this time, the first stage compressor unit 1 reaches the maximum discharge pressure. The compressed air enters the gas storage device 6 through the vent pipe 4 corresponding to the second stage compressor unit 1, so that the pressure in the gas storage device 6 reaches the maximum discharge pressure of the first stage compressor unit 1.

[0069] 1.5, the first stage compressor unit 1 is shut down, the anti-surge pipe 3 corresponding to the first stage compressor unit 1 is opened, the air injection valve 8 on the vent pipe 4 corresponding to the second stage compressor unit 1 is closed, the first shut-off valve 7 on the vent pipe 4 corresponding to the second stage compressor unit 1 is opened, and it is determined whether the pressure in the air storage device 6 has reached its initial set pressure target value. If yes, the first air injection of the compressed air energy storage system is completed; if no, the procedure of step S2 is followed.

[0070] S2, gas injection from the first stage compressor unit + the second stage compressor unit.

[0071] 2.1 Before the first stage compressor unit and the second stage compressor unit are injected with gas, the axial compressor stator vanes or centrifugal compressor guide vanes of each stage compressor unit are at their minimum operating angle. At this time, the anti-surge pipes 3 corresponding to each stage compressor unit 1 are opened in sequence, the vent pipes 4 corresponding to the other compressor units 1 except the first stage compressor unit 1 are closed, and the process vent pipes 9 are closed; the first shut-off valve 7 on the vent pipe 4 corresponding to the second stage compressor unit 1 is opened, and the first shut-off valve 7 corresponding to the other vent pipes 4 is closed; the gas injection valve 8 on the vent pipe 4 corresponding to the third stage compressor unit 1 is opened, the gas injection valve 8 on the vent pipe 4 corresponding to the other compressor units 1 is closed, the second shut-off valve 10 is closed, and the third shut-off valve 11 is opened.

[0072] 2.2 Start the first stage compressor unit 1. The other stages of compressor unit 1 are in a non-operating static state. After the first stage compressor unit 1 completes the speed increase under the drive of the main motor and is driven by the frequency converter to switch to the power frequency operation mode, start to slowly close the anti-surge pipeline 3 corresponding to the first stage compressor unit 1, so that the first stage compressor unit 1 is out of the blockage area and waits for the second stage compressor unit 1 to start.

[0073] 2.3 Start the second-stage compressor unit 1. After the second-stage compressor unit 1 completes the speed increase under the drive of the main motor and is switched to the power frequency operation mode by the frequency converter, start to slowly close the anti-surge pipeline 3 corresponding to the second-stage compressor unit 1, so that the second-stage compressor unit 1 is removed from the blockage area.

[0074] 2.4. Continuously and slowly alternately close the anti-surge pipe 3 corresponding to the first stage compressor unit 1 and the anti-surge pipe 3 corresponding to the second stage compressor unit 1 until they are completely closed. At the same time, slowly open the vent pipe 4 corresponding to the third stage compressor unit 1 until it is fully open.

[0075] 2.5 When the first stage compressor unit 1 and the second stage compressor unit 1 reach their maximum exhaust pressure, the air enters the gas storage device 6 through the vent pipe 4 corresponding to the third stage compressor unit 1, so that the pressure in the gas storage device 6 reaches the maximum exhaust pressure of the first stage compressor unit 1 and the second stage compressor unit 1.

[0076] 2.6. The first stage compressor unit 1 and the second stage compressor unit 1 are shut down. The anti-surge pipes 3 corresponding to the first stage compressor unit 1 and the second stage compressor unit 1 are opened. The air injection valve 8 on the vent pipe 4 corresponding to the third stage compressor unit 1 is closed. The first shut-off valve 7 on the vent pipe 4 corresponding to the third stage compressor unit 1 is opened, thereby restoring the function of the vent pipe 4. This allows for pressure relief through the vent pipe 4 in case of emergency overpressure. Then, it is determined whether the pressure in the air storage device 6 has reached its initial set pressure target value. If so, the first air injection of the compressed air energy storage system is completed. If not, the procedure in step S3 is followed.

[0077] S3, gas injection from the first-stage + second-stage + third-stage compressor unit.

[0078] 3.1 Before the first stage compressor unit, second stage compressor unit, and third stage compressor unit are injected with gas, the axial compressor stationary blades or centrifugal compressor guide vanes of each stage compressor unit are at their minimum operating angle, and the third stage compressor unit 1 adopts variable speed regulation and has no guide vane configuration.

[0079] At this time, the anti-surge pipes 3 corresponding to the first stage compressor unit 1, the second stage compressor unit 1, and the third stage compressor unit 1 are opened sequentially, and the vent pipes 4 corresponding to the second stage compressor unit 1 and the third stage compressor unit 1 are closed. However, the first shut-off valves 7 on the vent pipes 4 are all opened, and the process vent pipe 9 is closed. The air injection valves 8 on the vent pipes 4 corresponding to the second stage compressor unit 1 and the third stage compressor unit 1 are all closed. At the same time, the second shut-off valve 10 is closed, and the third shut-off valve 11 is opened.

[0080] 3.2 Start the first stage compressor unit 1. The other stages of compressor unit 1 are in a non-operating static state. After the first stage compressor unit 1 completes the speed increase under the drive of the main motor and is driven by the frequency converter to switch to the power frequency operation mode, slowly close the anti-surge pipeline 3 corresponding to the first stage compressor unit 1 so that the first stage compressor unit 1 is out of the blockage area.

[0081] 3.3 Start the second-stage compressor unit 1. After the second-stage compressor unit 1 completes the speed increase under the drive of the main motor and is switched to the power frequency operation mode by the frequency converter, slowly close the anti-surge pipeline 3 corresponding to the second-stage compressor unit 1 so that the second-stage compressor unit 1 is removed from the blockage area.

[0082] 3.4 Start the three-stage compressor unit 1. The three-stage compressor unit 1 is driven by the main motor to complete the speed increase and run to the minimum operating speed. In this embodiment, the driving method of the last stage compressor unit 1 is the variable speed regulation method.

[0083] 3.5 Slowly and alternately close the anti-surge pipe 3 corresponding to the first stage compressor unit 1, the anti-surge pipe 3 corresponding to the second stage compressor unit 1, and the anti-surge pipe 3 corresponding to the third stage compressor unit 1 until they are all closed. The exhaust pressure of the third stage compressor unit 1 gradually increases.

[0084] 3.6 Open the second shut-off valve 10, and gradually open the stationary vanes or guide vanes of the first stage compressor unit 1 and the second stage compressor unit 1 to increase the speed of the third stage compressor unit 1 and continuously increase the exhaust pressure of the third stage compressor unit 1 until the gas storage pressure of the artificial chamber is filled to the initial set pressure target value, thereby completing the first gas injection of the air compression energy storage system.

[0085] After the initial gas injection is completed, each compressor unit 1 will be shut down. If gas injection is required for four or more compressor units, follow the steps outlined above.

[0086] This embodiment primarily focuses on a compressed air energy storage system for gas storage in artificial chambers. Before the initial gas injection, the gas pressure inside the artificially excavated chamber is the same as the atmospheric pressure. At this stage, using an energy storage compressor unit for chamber gas injection deviates from the compressor unit's design operating conditions, resulting in high energy consumption. Therefore, research is needed on the gas injection process and methods to achieve the simplest gas injection pipeline and valve configuration to reduce investment costs and to achieve the fastest gas injection mode, thereby reducing initial gas injection energy consumption.

[0087] Currently, there is no international precedent for storing compressed air in artificial chambers; and there are even fewer application cases of using multi-stage axial-flow + centrifugal combined compressor units for gas storage in artificial chambers. This embodiment utilizes a large turbine compressor unit, which is used during normal energy storage, to achieve low-energy consumption and rapid gas injection. This eliminates the need to purchase a separate positive displacement compressor for the initial gas injection, and the increased gas filling rate will significantly shorten the project construction cycle.

[0088] Compared to traditional independent volumetric small compressor injection solutions, this solution significantly reduces injection time. For a 200,000 cubic meter artificial chamber, with an initial injection pressure of 0-11 MPa, a dual-row compressor unit can complete the process in approximately 40 hours, drastically shortening the injection time. Furthermore, compared to not optimizing the pipeline and using a standard injection system for the initial injection, which requires all three compressors to be running simultaneously, or restarting after the initial injection or subsequent maintenance of the artificial chamber, this solution saves over 50% of energy during the injection process.

[0089] The present invention has been tested and the process has been simulated, and the solution is feasible and reliable.

Claims

1. A compressed air energy storage system capable of low-energy initial air injection, characterized in that: It includes a series of multi-stage compressor units (1), multiple heat exchange separation units (2) corresponding to the multi-stage compressor units (1), multiple anti-surge pipes (3), multiple vent pipes (4), a vent silencer (5), and a gas storage device (6). Each heat exchange separation unit (2) is located between the outlet end of the corresponding compressor unit (1) and the inlet end of the next compressor unit (1). The outlet end of the last compressor unit (1) corresponding to the heat exchange separation unit (2) is connected to the gas storage device (6). The multiple anti-surge pipes (3) and multiple vent pipes (4) correspond one-to-one with the multiple compressor units (1); among them, the anti-surge pipe (3) and vent pipe (4) corresponding to the first compressor unit (1) are the same pipe, and their two ends are respectively connected to the outlet end of the first compressor unit (1) and the vent silencer (5); the two ends of the anti-surge pipes (3) corresponding to the other compressor units (1) are respectively connected to the outlet end of the previous compressor unit (1) and the outlet end of the corresponding compressor unit (1); the inlet end of the vent pipes (4) corresponding to the other compressor units (1) is respectively connected to the inlet end of the corresponding compressor unit (1), and the outlet end is divided into two paths, one of which is connected to the vent silencer (5) and is equipped with a first shut-off valve (7), and the other path is connected to the gas storage device (6) and is equipped with a gas injection valve (8); In the multi-stage compressor unit (1), a process venting pipe (9) is provided between the heat exchange separation unit (2) corresponding to the last stage compressor unit (1) and the venting silencer (5). The gas storage device (6) is provided with a second shut-off valve (10) and a third shut-off valve (11) at its inlet end. The second shut-off valve (10) is located at the outlet of the heat exchange separation unit (2) corresponding to the end compressor unit (1) and is used to open or shut off the gas passage compressed by the end compressor unit (1). The third shut-off valve (11) is located at the inlet of the gas storage device (6) and is used to adjust the gas pressure entering the gas storage device (6). The heat exchange separation unit (2) includes a heat exchanger (21) and a separator (22) connected in sequence. The heat exchanger (21) is located near the outlet end of the corresponding compressor unit (1) and is used to reduce the temperature of the compressed gas. The separator (22) is used to separate the compressed gas into gas and liquid. Each compressor unit (1) is provided with an outlet check valve (14) between its outlet end and the inlet end of the corresponding heat exchanger (21); the inlet end of the anti-surge pipe (3) corresponding to the first compressor unit (1) is located between the outlet end of the first compressor unit (1) and the outlet check valve (14) corresponding to the first compressor unit (1); the inlet end of the anti-surge pipe (3) corresponding to the other compressor units (1) is located between the outlet end of the corresponding compressor unit (1) and the corresponding outlet check valve (14), and the outlet end is located between the outlet check valve (14) corresponding to the previous compressor unit (1) and the heat exchanger (21); The process vent pipe (9) is located between the heat exchanger (21) and the vent silencer (5) corresponding to the terminal compressor unit (1).

2. The compressed air energy storage system with low energy consumption for initial air injection according to claim 1, characterized in that: The gas storage device (6) is an artificial chamber or pipeline steel.

3. The compressed air energy storage system capable of low-energy initial air injection according to claim 1 or 2, characterized in that: In the multi-stage compressor unit (1), the inlet end of the first stage compressor unit (1) is provided with an air filter (12) and an intake muffler (13) in sequence; the air filter (12) is used to filter impurities in the inlet air; the intake muffler (13) is located between the air filter (12) and the inlet end of the first stage compressor unit (1) and is used to eliminate noise generated by the inlet air.

4. The compressed air energy storage system capable of low-energy initial air injection according to claim 3, characterized in that: Except for the first compressor unit (1), the inlet end of the vent pipe (4) corresponding to the other compressor units (1) is located between the gas outlet end of the separator (22) corresponding to the previous compressor unit (1) and the inlet end of the corresponding compressor unit (1).

5. The compressed air energy storage system capable of low-energy initial air injection according to claim 4, characterized in that: The second shut-off valve (10) and the third shut-off valve (11) are electric shut-off valves or pneumatic shut-off valves.

6. A method for initial air injection of a compressed air energy storage system capable of low-energy initial air injection as described in any one of claims 1 to 5, characterized in that, Includes the following steps: S1, Gas injection into the first stage compressor unit 1.1 Open the anti-surge pipes (3) corresponding to each compressor unit (1), close the vent pipes (4) corresponding to the other compressor units (1) except the first compressor unit (1), and close the process vent pipes (9); open the gas injection valve (8) on the vent pipe (4) corresponding to the second compressor unit (1), and close the gas injection valves (8) corresponding to the other vent pipes (4); close each first shut-off valve (7) and second shut-off valve (10), and open the third shut-off valve (11); 1.2 Start the first compressor unit (1) and switch to the power frequency operation mode, while the other compressor units (1) are in a non-operational and static state; 1.3 Gradually open the guide vanes or stationary vanes of the first compressor unit (1) and gradually close the corresponding anti-surge pipe (3) until it is fully closed. At the same time, gradually open the corresponding vent pipe (4) of the second compressor unit (1) until it is fully open. 1.4 When the first stage compressor unit (1) reaches the maximum discharge pressure, the compressed air enters the gas storage device (6) through the vent pipe (4) corresponding to the second stage compressor unit (1), so that the pressure in the gas storage device (6) reaches the maximum discharge pressure of the first stage compressor unit (1). 1.5, the first stage compressor unit (1) is shut down, the anti-surge pipe (3) corresponding to the first stage compressor unit (1) is opened, the air injection valve (8) on the vent pipe (4) corresponding to the second stage compressor unit (1) is closed, the first shut-off valve (7) on the vent pipe (4) corresponding to the second stage compressor unit (1) is opened, and it is determined whether the pressure in the air storage device (6) has reached its initial set pressure target value. If yes, the first air injection of the compressed air energy storage system is completed; if no, the method of step S2 is followed. S2, gas injection from the first stage + second stage compressor unit. 2.1 Based on step 1.5, close the vent pipe (4) corresponding to the second-stage compressor unit (1) and open the gas injection valve (8) on the vent pipe (4) corresponding to the third-stage compressor unit (1); 2.2 Start the first stage compressor unit (1), while the other compressor units (1) are in a non-operating static state. After the first stage compressor unit (1) switches to the power frequency operation mode, start to slowly close the anti-surge pipeline (3) corresponding to the first stage compressor unit (1) to allow the compressor to leave the blockage area and then stop closing, waiting for the second stage compressor unit (1) to start. 2.3 Start the second-stage compressor unit (1). After the second-stage compressor unit (1) switches to the power frequency operation mode, start to slowly close the anti-surge pipeline (3) corresponding to the second-stage compressor unit (1). 2.

4. Continuously and slowly alternately close the anti-surge pipeline (3) corresponding to the first stage compressor unit (1) and the anti-surge pipeline (3) corresponding to the second stage compressor unit (1) until they are completely closed. At the same time, slowly open the vent pipeline (4) corresponding to the third stage compressor unit (1) until it is fully open. 2.5 When the first stage compressor unit (1) and the second stage compressor unit (1) reach the maximum exhaust pressure, the air enters the gas storage device (6) through the vent pipe (4) corresponding to the third stage compressor unit (1), so that the pressure in the gas storage device (6) reaches the maximum exhaust pressure of the first stage compressor unit (1) and the second stage compressor unit (1); 2.

6. The first stage compressor unit (1) and the second stage compressor unit (1) are shut down. The anti-surge pipes (3) corresponding to the first stage compressor unit (1) and the second stage compressor unit (1) are opened. The air injection valve (8) on the vent pipe (4) corresponding to the third stage compressor unit (1) is closed. The first shut-off valve (7) on the vent pipe (4) corresponding to the third stage compressor unit (1) is opened. It is determined whether the pressure in the air storage device (6) has reached its initial set pressure target value. If yes, the first air injection of the compressed air energy storage system is completed. If no, the method of step S3 is followed. S3, according to the methods of steps 2.1 to 2.6, perform air injection for the first stage compressor unit (1) before the last stage compressor unit (1) until the pressure in the air storage device (6) reaches its initial set pressure target value, then the first air injection of the compressed air energy storage system is completed; if the pressure in the air storage device (6) still does not reach its initial set pressure target value after the air injection of the first stage compressor unit (1) before the last stage compressor unit (1) is completed, then the method of step S4 is executed; S4, First stage + Second stage + ... + Final stage compressor unit gas injection 4.1 Open the anti-surge pipes (3) corresponding to each compressor unit (1), close the vent pipes (4) corresponding to the other compressor units (1) except the first compressor unit (1), and close the process vent pipes (9); open each first shut-off valve (7), close each gas injection valve (8), close the second shut-off valve (10), and open the third shut-off valve (11); 4.

2. Following steps 2.2 to 2.4, start each section compressor unit (1) in sequence. When starting the last section compressor unit (1), slowly and alternately close the anti-surge pipelines (3) corresponding to the first, second and... last section compressor units (1) until they are all closed. At the same time, open the second shut-off valve (10). 4.3 Air passes through the first stage, second stage... final stage compressor unit (1) in sequence and then enters the gas storage device (6) through the pipeline between the final stage compressor unit (1) and the gas storage device (6), thus completing the first gas injection of the compressed air energy storage system.

7. The initial air injection method for a compressed air energy storage system capable of low-energy initial air injection according to claim 6, characterized in that: In step 4.2, the driving mode of the terminal compressor unit (1) is variable speed regulation.

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