A compressed air energy storage system and method for waste heat recovery

Abstract

In order to solve the technical problem of low electric-electric conversion efficiency caused by poor exhaust temperature stability of the existing air compression energy storage system, a compressed air energy storage system and method for recycling waste heat are provided, wherein the energy storage system increases a first waste heat exchanger between every two adjacent compressor groups, increases a second waste heat exchanger after the last compressor group, and combines a cooling tower to cool the waste heat of each compressor group; meanwhile, a branch pipe is introduced to the inlet of the air filter on the circulating water return pipe of the cooling tower, the air temperature at the inlet of the first compressor group is heated to a set value by waste heat, so as to realize the recycling of waste heat, guarantee the demand of the rated power output of the compressor group, and further provide the electric-electric conversion efficiency of the system.

Description

Technical Field

[0001] This invention relates to compressed air energy storage devices, and more particularly to a compressed air energy storage system and method for waste heat recovery. Background Technology

[0002] Compressed air energy storage, as a type of large-scale grid-scale energy storage, is considered one of the most promising energy storage methods for the future. It features 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 (rock cave, salt cavern, or container), 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 then enters an expansion turbine to rotate and do work, thereby driving a generator to generate electricity and connect to the grid.

[0004] Based on their operating principles, compressed air energy storage systems can be divided into two categories: supplementary combustion type and non-supplementary combustion type.

[0005] (1) Compressed Air Energy Storage (CAES): This technology is based on gas turbine power generation technology. The system operation relies on the consumption of large amounts of fossil fuels such as natural gas to achieve the system's cyclical operation. Representative engineering projects include the 290MW Huntorf power plant in Germany (built in 1978) and the 110MW McIntosh power plant in the United States (built in 1991). Due to the presence of fuel combustion, CAES systems generate carbon emissions, which limits their development. Therefore, although this technology still has market applications, research and development are basically stagnant, and market promotion and application are limited. At the same time, CAES systems do not store the heat of the compression process. The compressor operates in a near-isothermal compression manner, and there is no need to control the compressor's exhaust temperature, making the entire compression process relatively simple.

[0006] (2) Non-combustion Compressed Air Energy Storage Technology: This energy storage technology adopts a thermo-compression storage method, storing the heat generated during the compression process as thermal energy in a heat storage tank. During peak electricity demand, the heat of compression is fed back to the air entering the expander to perform work during the energy release stage, thereby improving the overall efficiency of the system and achieving combustion-free and emission-free energy storage. This type of compressed air energy storage system with a heat storage component is also known as an advanced adiabatic compressed air energy storage system (adiabatic CAES, abbreviated as A-CAES). The A-CAES system utilizes heat storage to replace fossil fuel combustion, without consuming fuel, thus having outstanding advantages in terms of economy and environmental protection compared to traditional systems. This energy storage technology is currently a hot topic in industry research and a key direction for market application. Because it is necessary to store the heat generated during the compression process, the exhaust temperature of the compressor needs to be stable, especially for the first stage compressor that draws air from the atmosphere, where controlling the stability of its exhaust temperature is quite difficult. The main reason is that the temperature difference varies greatly throughout the year, especially in China. Compressor units are generally designed with a pressure ratio based on the annual average operating conditions. When the ambient temperature is low in winter, the outlet temperature of one section of the compressor will decrease synchronously. Since the inlet of this section does not take into account the use of waste heat for heating, it will be difficult for the power generation side to stably output the rated power, and it will also reduce the system's electricity-to-electricity conversion efficiency. Summary of the Invention

[0007] The purpose of this invention is to solve the technical problem of low electro-electric conversion efficiency caused by poor exhaust temperature stability in existing compressed air energy storage systems, and to provide a compressed air energy storage system and method for waste heat reuse.

[0008] To achieve the above objectives, the technical solution of the present invention is as follows:

[0009] A compressed air energy storage system that reuses waste heat, characterized by the following features:

[0010] It includes an inlet unit, an outlet unit, a cooling tower, and an N-stage compressor unit connected in series between the inlet unit and the outlet unit, where N≥3;

[0011] A first heat exchange separation unit is provided between each two adjacent compressor units; a second heat exchange separation unit is provided between the outlet end of the Nth compressor unit and the outlet unit;

[0012] The first heat exchange and separation unit includes a heat storage heat exchanger, a first waste heat heat exchanger and a first separator arranged in sequence, wherein the heat storage heat exchanger is close to the outlet end of the preceding stage compressor unit and the first separator is close to the inlet end of the following stage compressor unit.

[0013] The second heat exchange and separation unit includes a second waste heat exchanger and a second separator connected to each other, wherein the second waste heat exchanger is located near the outlet end of the Nth stage compressor unit;

[0014] The inlet unit includes an air filter, the outlet of which is connected to the air inlet of the first-stage compressor unit; the first waste heat exchanger and the second waste heat exchanger exchange heat through a cooling tower, and one of the return water pipes of the cooling tower provides a heat source for the inlet air of the air filter.

[0015] The outlet unit includes a pneumatic shut-off valve and a salt cavern or gas storage tank located at the rear end of the pneumatic valve. The salt cavern or gas storage tank is used to store the heat energy compressed by the Nth stage compressor unit.

[0016] Furthermore, it also includes N outlet check valves, N anti-surge valves, and N unit vent valves;

[0017] The N outlet check valves are located between the outlet end of the corresponding compressor unit and the heat storage heat exchanger or the second waste heat heat exchanger. They are used to prevent high-pressure air from the downstream compressor unit from entering the upstream compressor unit when the anti-surge valve of each compressor unit is fully open, thus preventing the upstream compressor unit from overpressure.

[0018] The N anti-surge valves are located between the outlet check valves of adjacent two-stage compressor units, and are used for independent anti-surge of each compressor stage.

[0019] The N unit vent valves are located at the front end of the corresponding outlet check valve, and the other end is open to the atmosphere. They are used for overpressure control during the loading and operation of the compressor unit and for pressure relief after shutdown.

[0020] Furthermore, an inlet heat exchanger is provided at the inlet of the air filter. This inlet heat exchanger is a finned tube heat exchanger. One of the return water pipes of the cooling tower passes through the inlet heat exchanger, thereby providing a heat source for the inlet air.

[0021] Furthermore, a third separator is provided between the heat storage heat exchanger and the first waste heat heat exchanger.

[0022] Furthermore, it also includes a condensate recovery device, in which condensate from the first separator, the second separator, and the third separator all flow into the condensate recovery device through pipelines.

[0023] Furthermore, the inlet unit also includes an intake muffler located between the air filter and the first-stage compressor unit.

[0024] Furthermore, the outlet unit also includes an electrically operated shut-off valve; the electrically operated shut-off valve is located between the inlet end of the salt cavern or gas storage tank and the pneumatic shut-off valve; or the electrically operated shut-off valve is located at the front end of the pneumatic shut-off valve.

[0025] Furthermore, the outlet unit also includes a venting silencer connected to the other end of the N unit venting valves, used to reduce the noise when the compressor unit vents.

[0026] Furthermore, a process vent valve is provided between the second separator and the vent silencer for releasing high-pressure air from containers and pipelines at the second separator when the compressor unit stops.

[0027] Furthermore, the present invention also provides a compressed air energy storage method for waste heat recovery, comprising the following steps:

[0028] Step 1: The air that has passed through the air filter enters the first-stage compressor unit and is compressed;

[0029] Step 2: The compressed air passes through the heat storage heat exchanger, the first waste heat heat exchanger and the first separator in sequence before entering the second stage compressor unit, and then passes through each stage of the compressor unit in sequence through the same path before entering the Nth stage compressor unit.

[0030] Step 3: The air compressed by the Nth stage compressor unit passes through the second waste heat exchanger and the second separator and is then stored in a salt cavern or energy storage tank.

[0031] Step 4: The air at the inlet of the air filter is heated through one of the return water pipes of the first waste heat exchanger and / or the second waste heat exchanger, so that the air at the inlet of the first-stage compressor unit reaches the set temperature.

[0032] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0033] 1. The air compression energy storage system of the present invention utilizes the waste heat of the system process. A first waste heat exchanger is added between every two adjacent compressor units, and a second waste heat exchanger is added after the last compressor unit. Combined with a cooling tower, the waste heat of each compressor unit is cooled. At the same time, a branch pipe is led from the circulating water return pipe of the cooling tower through the air filter inlet, and the air temperature at the inlet of the first compressor unit is heated to a set value by the waste heat, thereby realizing the reuse of waste heat and ensuring the rated power output of the compressor unit, thereby improving the system's electricity-to-electricity conversion efficiency.

[0034] 2. The air compression energy storage system of the present invention can avoid the air filter from freezing in winter, which would cause the air filter cartridge to freeze and become blocked, thereby improving the reliability and stability of the compressor unit and the energy storage system.

[0035] 3. The air filter of the present invention is provided with a heat exchanger on the outside, and the heat exchanger is selected as a plate-shaped tube-fin heat exchanger. The heat exchanger draws air from all sides of the air filter, thereby improving the uniformity of heat exchange of the air at the air inlet. Attached Figure Description

[0036] Figure 1This is a schematic diagram of an embodiment of the compressed air energy storage system for waste heat reuse according to the present invention.

[0037] The attached figures are labeled as follows:

[0038] 1-Cooling tower, 2-Compressor unit, 21-Outlet check valve, 22-Anti-surge valve, 23-Unit vent valve, 3-First heat exchange separation unit, 31-Regenerative heat exchanger, 32-First waste heat exchanger, 33-First separator, 34-Third separator, 4-Second heat exchange separation unit, 41-Second waste heat exchanger, 42-Second separator, 5-Air filter, 51-Inlet heat exchanger, 6-Pneumatic shut-off valve, 7-Air storage tank, 8-Inlet silencer, 9-Electric shut-off valve, 10-Vent silencer, 11-Process vent valve. Detailed Implementation

[0039] 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.

[0040] The two existing operational international supplemental combustion compressed air energy storage power plants do not require the storage of compression heat and have not considered solutions for stabilizing the compressor's intake air temperature from the atmosphere. The 60MW energy storage project in Jintan, Jiangsu, which is already operational domestically, also does not seem to have considered or optimized this aspect. In existing process industries, where compressor inlet air heating is present, steam heating is often used; solutions using waste heat circulating water for heating are not seen. This invention analyzes the process flow and heat balance of non-supplemental combustion compressed air energy storage technology, utilizing waste heat that cannot be stored in the system to heat the air drawn in from the ambient atmosphere. This ensures that the air temperature entering the compressor remains constant during compressor operation and winter conditions (or when the temperature is below the annual average design temperature), maintaining a constant inlet temperature for the first stage of the compressor, thereby achieving a constant exhaust temperature for the first stage of the compressor unit, which is beneficial for recovering stable compression heat.

[0041] like Figure 1 As shown, the present invention provides a compressed air energy storage system for waste heat reuse. The system includes an inlet unit, an outlet unit, a cooling tower 1, and an N-stage compressor unit 2 connected in series between the inlet unit and the outlet unit, wherein N≥3, and the number of stages of the compressor unit 2 can be set according to the energy storage requirements and site planning.

[0042] A first heat exchange separation unit 3 is provided between each two adjacent compressor units 2. The first heat exchange separation unit 3 includes a heat storage heat exchanger 31, a third separator 34, a first waste heat heat exchanger 32, and a first separator 33 arranged sequentially along the pipeline. The heat storage heat exchanger 31 is close to the outlet end of the preceding compressor unit 2. The third separator 34 is used to separate the air after heat exchange by the heat storage heat exchanger 31 into gas and liquid. The first waste heat heat exchanger 32 is located at the rear end of the third separator 34 and is used to exchange heat with the separated air again. The first separator 33 is close to the inlet end of the following compressor unit 2. After the air is separated by the first separator 33 after being heat exchanged again, the gas enters the next compressor unit 2 through the pipeline.

[0043] A second heat exchange separation unit 4 is provided between the outlet end of the Nth stage compressor unit 2 and the outlet unit. The second heat exchange separation unit 4 includes a second waste heat exchanger 41 and a second separator 42 connected to each other. The second waste heat exchanger 41 is close to the outlet end of the Nth stage compressor unit 2 and is used to exchange heat with the air passing through the Nth stage compressor unit 2. The second separator 42 is located at the rear end of the second waste heat exchanger 41 and performs further separation on the heat-exchanged air. After the gas reaches a predetermined temperature, it enters the salt cavern or gas storage tank 7 through a pipeline.

[0044] To achieve energy reuse, the present invention also includes a condensate recovery device, which can recover the condensate generated during the separation process of the first separator 33, the second separator 42 and the third separator 34 to the cooling tower 1 through a pipeline, thereby realizing the recycling of resources.

[0045] The first waste heat exchanger 32 and the second waste heat exchanger 41 exchange heat through the cooling tower 1, thereby improving the stability of the air temperature at the inlet of each stage of the compressor unit 2.

[0046] The inlet unit is located at the inlet end of the first-stage compressor unit 2 and includes an air filter 5 and an intake muffler 8. The intake muffler 8 is located between the air filter 5 and the air inlet of the first-stage compressor unit 2 and is used to reduce or eliminate noise from the inlet air in the pipeline. In this embodiment, an inlet heat exchanger 51 is provided on the outside of the air filter 5. The inlet heat exchanger 51 is a finned tube heat exchanger that uses a self-cleaning air intake method. It filters and heats the air at the inlet simultaneously. The air at the inlet is stratified and enters the air filter 5 from all sides after passing through the inlet heat exchanger 51, thereby ensuring the uniformity of inlet air filtration and heating.

[0047] In order to reuse waste heat, in this embodiment, one of the return water pipes of the cooling tower 1 is connected through the inlet heat exchanger 51 to provide a heat source for the inlet heat exchanger 51, thereby enabling the temperature of the inlet air of the first-stage compressor unit 2 to reach the set value.

[0048] The outlet unit includes a pneumatic shut-off valve 6 and a salt cavern or gas storage tank 7 located downstream of the pneumatic shut-off valve 6. The salt cavern or gas storage tank 7 is used to store the heat energy compressed by the Nth stage compressor unit 2. Alternatively, an artificial chamber or container room can be used for heat energy storage. To ensure smooth shut-off, an electric shut-off valve 9 is also installed upstream of the pneumatic shut-off valve 6 or between the pneumatic shut-off valve 6 and the salt cavern or gas storage tank 7. The shut-off method can be selected; generally, the pneumatic shut-off valve 6 is used to close the outlet channel of the outlet unit. When the gas supply is insufficient, the electric shut-off valve 9 can be used to close the outlet channel, thereby improving system safety. A flow meter is installed between the pneumatic shut-off valve 6 or the electric shut-off valve 9 of the outlet unit and the salt cavern or gas storage tank 7 for constant flow control of the gas injection process of the compressor unit 2.

[0049] To further improve the operational safety of the air compression energy storage system, this embodiment also includes N outlet check valves 21, N anti-surge valves 22, and N unit vent valves 23, wherein the number N corresponds to the number of stages of the compressor unit. The N outlet check valves 21 are located between the outlet end of the corresponding compressor unit 2 and the heat storage heat exchanger 31 or the second waste heat exchanger 41, respectively, to prevent high-temperature, high-pressure air from flowing back into the previous stage compressor unit 2, thereby affecting the safety of the previous stage compressor unit 2. The N anti-surge valves 22 are located between the outlet check valves 21 of adjacent two-stage compressor units 2, respectively, for independent anti-surge protection of that section of compressor and backflow regulation during loading and operation. One end of each of the N unit vent valves 23 is located at the front end of the corresponding outlet check valve 21, and the other end is connected to a vent silencer 10. When the air pressure in a certain stage compressor unit 2 is higher than the set value, the corresponding unit vent valve 23 is opened until the air pressure in the compressor unit returns to normal, and then the corresponding unit vent valve 23 is closed. The vent silencer 10 is set to reduce the noise of the compressor unit 2 during the venting process.

[0050] The present invention also provides a process vent valve 11 at the rear end of the second separator 42 corresponding to the N-stage compressor unit 2, which is used to release the high-pressure air in the container and pipeline at the second separator 42 when the compressor unit 2 is stopped. The other end of the process vent valve 11 is connected to the vent silencer 10, also to reduce the noise of the compressor unit during the venting process.

[0051] Furthermore, this invention also provides a compressed air energy storage method for waste heat recovery, implemented using the aforementioned compressed air energy storage system for waste heat recovery. This embodiment uses a three-stage compressor unit as an example for illustration, and specifically includes the following steps:

[0052] Step 1: The first-stage compressor unit 2 draws in air from the atmosphere. The air passes through the air filter 5 and the intake silencer 8 in sequence before entering the first-stage compressor unit 2 for pressurization. The first-stage compressor unit 2 is an axial flow compressor. Axial flow compressors are highly efficient and suitable for large flow rates. Generally, the outlet temperature of the first-stage compressor unit 2 is 190-600℃. The specific temperature can be set according to the actual working conditions.

[0053] Step 2: After the pressurized air flows out of the first-stage compressor unit 2, it passes through the outlet check valve 21, heat storage heat exchanger 31, third separator 34, first waste heat heat exchanger 32 and first separator 33 corresponding to the first-stage compressor unit 2 in sequence before entering the second-stage compressor unit 2 for pressurization. The inlet temperature of the second-stage compressor unit 2 is set to 40℃ and the exhaust temperature is 190~600℃. The specific temperature can be set according to the actual working conditions.

[0054] Step 3: After the high-temperature air is discharged from the second-stage compressor unit 2, it passes through the outlet check valve 21, heat storage heat exchanger 31, third separator 34, first waste heat heat exchanger 32 and first separator 33 corresponding to the first-stage compressor unit 2 in sequence before entering the third-stage compressor unit 2 for pressurization. The inlet temperature of the third-stage compressor unit 2 is set to 40°C, and the exhaust temperature is generally about 70 to 200°C.

[0055] Step 4: After flowing out of the third-stage compressor unit 2, the high-temperature air passes through the outlet check valve 21, the second waste heat exchanger 41 and the second separator 42 corresponding to the third-stage compressor unit 2 in sequence, and then enters the salt cavern or energy storage tank 7 through the pipeline for storage.

[0056] Step 5: The first waste heat exchanger 32 and the second waste heat exchanger 41 exchange heat through the cooling tower 1. In this embodiment, the cooling tower 1 includes an inlet water pipe and a return water pipe. The first waste heat exchanger 32 of the first-stage compressor unit and the second-stage compressor unit generally cools air at about 70°C to 40°C through the circulating water in the inlet water pipe of the cooling tower 1, while the temperature of the circulating cooling water in the return water pipe of the cooling tower 1 increases from 32°C to 40°C. The second waste heat exchanger 41 cools the air from about 100°C to 40-50°C, and the temperature of the circulating cooling water in the return water pipe of the cooling tower 1 also increases from 32°C to 40°C. On the return water pipe of the circulating water in the cooling tower 1 that exchanges heat through the first waste heat exchanger 32 and the second waste heat exchanger 41, a branch pipe is led to provide a heat source to the inlet heat exchanger 51 outside the intake air filter 5, thereby ensuring that the inlet air of the first-stage compressor unit 2 reaches the set temperature, and thus improving the stability of the exhaust temperature of the energy storage system.

[0057] In this embodiment, the compressor units at each stage are designed and selected based on the annual average temperature. According to field tests, when the inlet air temperature is 11.3℃, the exhaust temperature of the first-stage compressor unit can reach 360℃. When the ambient temperature is below 11.3℃, the air can be heated to 11.3℃ using the 40℃ circulating water in the return water pipe of cooling tower 1. Reheating can also be achieved when the ambient temperature is below the annual average temperature through water flow adjustment. Based on heat load calculations, the heat generated by the waste heat exchanger of the three-stage compressor unit can meet the reheating heat requirement of the inlet air. Therefore, only a small portion of the circulating water, typically 1 / 3, is recycled from the main pipe of cooling tower 1 to the inlet air filter 5.

[0058] As an alternative, the location of the tube-fin heat exchanger in this embodiment can be configured as an electric heater, or a stream of high-temperature air can be introduced from the outlet of the first-stage compressor unit and recirculated into the pipe behind the compressor intake air filter 5 to increase the intake air temperature. If a recirculation scheme is adopted, the power consumed by the drive motor of the first-stage compressor unit will increase. Calculations show that when the ambient intake air temperature is the average winter temperature of 2.1℃, if the inlet air temperature is heated to 11.3℃, under typical process parameters, the compressor unit's operating flow rate is approximately 1200 t / h, requiring approximately 3000 kW of electrical power. The appropriate scheme can be selected based on the actual situation.

[0059] The technical solution of this invention has been tested and simulated, and the solution is feasible and reliable.

[0060] Although embodiments of the present invention have been shown and described above, those skilled in the art should consider any variations and modifications of the above embodiments that fall within the scope of the present invention's spirit and essence to be within the protection scope of the present invention.

Claims

1. A compressed air energy storage system for waste heat recovery, characterized in that: It includes an inlet unit, an outlet unit, a cooling tower (1), and an N-stage compressor unit (2) connected in series between the inlet unit and the outlet unit, wherein N≥3; A first heat exchange separation unit (3) is provided between each two adjacent compressor units (2); a second heat exchange separation unit (4) is provided between the outlet end of the Nth stage compressor unit (2) and the outlet unit. The first heat exchange separation unit (3) includes a heat storage heat exchanger (31), a first waste heat heat exchanger (32) and a first separator (33) arranged in sequence, wherein the heat storage heat exchanger (31) is close to the outlet end of the preceding stage compressor unit (2) and the first separator (33) is close to the inlet end of the following stage compressor unit (2); The second heat exchange separation unit (4) includes a second waste heat exchanger (41) and a second separator (42) connected to each other, wherein the second waste heat exchanger (41) is close to the outlet end of the Nth stage compressor unit (2); The inlet unit includes an air filter (5), the outlet end of which is connected to the air inlet of the first-stage compressor unit (2); the first waste heat exchanger (32) and the second waste heat exchanger (41) exchange heat through a cooling tower (1), and one of the return water pipes of the cooling tower (1) provides a heat source for the inlet air of the air filter (5); The outlet unit includes a pneumatic shut-off valve (6) and a salt cavern or gas storage tank (7) located at the rear end of the pneumatic shut-off valve (6), the salt cavern or gas storage tank (7) being used to store the thermal energy compressed by the Nth stage compressor unit (2).

2. The compressed air energy storage system for waste heat reuse according to claim 1, characterized in that: It also includes N outlet check valves (21), N anti-surge valves (22) and N unit vent valves (23); The N outlet check valves (21) are respectively located between the outlet end of the corresponding compressor unit (2) and the heat storage heat exchanger (31) or the second waste heat heat exchanger (41); The N anti-surge valves (22) are located between the outlet check valves (21) of the two adjacent compressor units (2); One end of each of the N unit vent valves (23) is located at the front end of the corresponding outlet check valve (21), and the other end is open to the atmosphere.

3. The compressed air energy storage system for waste heat reuse according to claim 2, characterized in that: An inlet heat exchanger (51) is provided at the inlet of the air filter (5). The inlet heat exchanger (51) is a plate-shaped tube-fin heat exchanger. One of the return water pipes of the cooling tower (1) passes through the inlet heat exchanger (51) to provide a heat source for the inlet air.

4. The compressed air energy storage system for waste heat reuse according to claim 3, characterized in that: A third separator (34) is also provided between the heat storage heat exchanger (31) and the first waste heat heat exchanger (32).

5. The compressed air energy storage system for waste heat reuse according to claim 4, characterized in that: It also includes a condensate recovery device, in which the condensate from the first separator (33), the second separator (42) and the third separator (34) all flow into the condensate recovery device through pipes.

6. The compressed air energy storage system for waste heat reuse according to claim 5, characterized in that: The inlet unit also includes an intake muffler (8), which is located between the air filter (5) and the first-stage compressor unit (2).

7. The compressed air energy storage system for waste heat reuse according to claim 6, characterized in that: The outlet unit also includes an electric shut-off valve (9); the electric shut-off valve (9) is located between the inlet end of the salt cave or gas storage tank (7) and the pneumatic shut-off valve (6); or, the electric shut-off valve (9) is located at the front end of the pneumatic shut-off valve (6).

8. The compressed air energy storage system for waste heat reuse according to claim 7, characterized in that: The outlet unit also includes a vent silencer (10) connected to the other end of the vent valves (23) of the N units.

9. The compressed air energy storage system for waste heat reuse according to claim 8, characterized in that: A process vent valve (11) is also provided between the second separator (42) and the vent silencer (10).

10. A method for compressed air energy storage that utilizes waste heat, characterized in that, The compressed air energy storage system for waste heat reuse according to any one of claims 1 to 9 includes the following steps: Step 1: The air passing through the air filter (5) enters the first-stage compressor unit (2) and is compressed; Step 2: The compressed air passes through the heat storage heat exchanger (31), the first waste heat heat exchanger (32) and the first separator (33) in sequence before entering the second stage compressor unit (2), and then passes through each stage compressor unit (2) in sequence through the same path before entering the Nth stage compressor unit (2). Step 3: The air compressed by the Nth stage compressor unit (2) passes through the second waste heat exchanger (41) and the second separator (42) and then enters the salt cavern or air storage tank (7) for storage. Step 4: The air at the inlet of the air filter (5) is heated through one of the return water pipes of the first waste heat exchanger (32) and / or the second waste heat exchanger (41) to reach the set temperature.

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