Air carbon capture system coupled with compressed air energy storage and capture method thereof

Abstract

The invention discloses an air carbon capture system coupled with compressed air energy storage and a capture method thereof. The air carbon capture system comprises a compressed air energy storage system, a heat recovery system and an air carbon capture system, the compressed air energy storage system comprises a multi-stage air compression device, a compressed air storage facility and an air turbine unit; the air carbon capture system comprises a CO2 adsorption-desorption reactor and a CO2 storage tank; the CO2 adsorption-desorption reactor is arranged between two certain stages of compressors of the multi-stage air compression device; the heat recovery system comprises a heat storage tank and a normal-temperature tank. According to the invention, the air carbon capture system is coupled with the compressed air energy storage system, so that the adverse effect of water vapor in air on the selectivity and adsorption capacity of the adsorption material can be reduced, and compared with the traditional direct air carbon capture system, the air capture energy consumption is reduced, the CO2 desorption energy consumption is reduced, and the energy utilization efficiency is improved.

Description

Technical Field

[0001] The invention relates to an air carbon capture system coupled with compressed air energy storage and a capture method thereof, belonging to the technical field of carbon dioxide capture. Background Art

[0002] Due to the development of industrialization, the combustion of large amounts of fossil fuels has intensified the emission of greenhouse gas CO2. Global CO2 emissions caused by the combustion of fossil fuels exceed 35 billion tons each year. Nearly 50% of global CO2 emissions come from distributed sources. Distributed sources such as flue gas from small and medium-sized boilers, industrial exhaust, and vehicle exhaust are characterized by small individual emissions, wide distribution, and large numbers. The CO2 emission base of distributed sources is large, among which the CO2 stock in the air is the largest, but due to its lowest concentration, it is the most difficult to capture. Direct Air Capture (DAC) is a technology that directly captures and obtains high-concentration CO2 from the air. It has the potential to process CO2 emissions from distributed sources and provides solutions for some areas that are difficult to reduce emissions in a short period of time (such as long-distance transportation and the chemical industry).

[0003] The main technical routes of DAC include chemical absorption, solid adsorption and variable humidity adsorption. The chemical absorption method usually absorbs carbon dioxide in the air through alkaline solutions such as NaOH and Ca(OH)2, and obtains product gas by calcining the precipitated carbonate. Its disadvantages are: the calcination temperature exceeds 800°C in the regeneration stage, and there is water consumption during the adsorption process, which consumes a lot of energy. Compared with the solution absorption method, the regeneration temperature of solid adsorption technology is more suitable, ranging from 80-150°C, avoiding the high latent heat of heating the absorption liquid, and has obvious advantages in reducing equipment corrosion and anti-degradation. The variable humidity adsorption method drives the adsorption / desorption of the adsorbent through changes in temperature and humidity, but in terms of rapid industrial application, its technical maturity is not as good as solid adsorption and chemical absorption. Therefore, the technical route of solid adsorption in the field of direct air carbon capture is more extensive and feasible.

[0004] Since the CO2 partial pressure in the air is small (40Pa) and the volume fraction is low (4.2×10 -4 ), the existing solid adsorption technology still faces the problems of high actual capture cost, high energy consumption in the air capture and CO2 regeneration stages, and immature capture devices and processes. In addition, for common physical adsorption materials such as zeolite molecular sieves and metal organic frameworks, water vapor in the air also has an adverse effect on the selectivity and adsorption capacity of the adsorption material. Adding air dehumidification equipment will further increase equipment costs and system energy consumption. Therefore, how to make full use of waste heat, low-grade heat sources and renewable energy, optimize the DAC process flow, and reduce the energy consumption and comprehensive cost of the DAC system is a technical problem that technicians in this field urgently need to solve. Summary of the invention

[0005] The purpose of the present invention is to solve the problems of low CO2 partial pressure in the air, high energy consumption and cost of DAC technology, and the adsorption effect of adsorbent being greatly affected by air humidity. An air carbon capture system and method coupled with compressed air energy storage is developed to reduce the blast energy consumption and regeneration energy consumption of the DAC system, reduce the influence of moisture on the adsorption effect of the adsorbent, and improve energy utilization efficiency.

[0006] In order to achieve the above technical objectives and the above technical effects, this application is implemented through the following technical solutions:

[0007] In the first aspect, the present invention provides an air carbon capture system coupled with compressed air energy storage, comprising a compressed air energy storage system, a heat recovery system and an air carbon capture system; the compressed air energy storage system comprises a multi-stage air compression device, a compressed air storage facility and an air turbine unit, the multi-stage air compression device has a plurality of single-stage compressors interconnected; the air carbon capture system comprises a CO2 adsorption-desorption reactor and a CO2 storage tank, the CO2 adsorption-desorption reactor is provided with an air channel and a heat storage medium channel; the heat recovery system comprises a heat storage tank and a normal temperature tank; the CO2 adsorption-desorption reactor is arranged between any two-stage compressors of the multi-stage air compression device, the air channel inlet of the CO2 adsorption-desorption reactor is connected to the outlet of the compressor of the previous stage, and the air channel outlet is connected through a bypass The bypass is connected to the inlet of the next compressor, the inlet of the CO2 storage tank and the atmosphere respectively; the outlet of the multi-stage air compression device is connected to the inlet of the compressed air storage facility, and the outlet of the compressed air storage facility is connected to the inlet of the air turbine unit; the outlet of the air turbine unit is connected to the atmosphere and is connected to the air channel inlet of the CO2 adsorption-desorption reactor through a bypass; the inlet of the heat storage tank is connected to the heat storage medium outlets of the multi-stage air compression device and the CO2 adsorption-desorption reactor respectively, and the outlet of the heat storage tank is connected to the heat storage medium inlet of the air turbine unit and the CO2 adsorption-desorption reactor respectively; the inlet of the normal temperature tank is connected to the heat storage medium channel outlet of the air turbine unit, and the outlet of the normal temperature tank is connected to the heat storage medium inlet of the multi-stage air compression device; at least one valve is provided between each of the bypasses for switching.

[0008] Preferably, the heat storage medium in the heat storage tank and the normal temperature tank includes but is not limited to water, heat transfer oil or molten salt.

[0009] Preferably, the multi-stage air compression device comprises 2-5 stage compressors, and at least one CO2 adsorption-desorption reactor is provided. When multiple CO2 adsorption-desorption reactors are provided, the multiple CO2 adsorption-desorption reactors are arranged between any two stages of compressors that are interconnected; when a single CO2 adsorption-desorption reactor is provided, the CO2 adsorption-desorption reactor is arranged between any two stages of compressors.

[0010] Preferably, the air channel of the CO2 adsorption-desorption reactor is filled with a CO2 adsorption material, and the CO2 adsorption material may be a physical adsorbent such as activated carbon, zeolite, or a chemical adsorbent such as solid amine.

[0011] In a second aspect, the present invention provides an air carbon capture method coupled with compressed air energy storage, which uses the above-mentioned air carbon capture system coupled with compressed air energy storage for capture, comprising the following steps:

[0012] The multi-stage compression device pressurizes the air in multiple stages, the CO2 adsorption-desorption reactor adsorbs CO2 in the compressed air to realize the CO2 adsorption process, the heat storage tank stores the heat energy generated by the compressed air, and the air without CO2 is stored through the compressed air storage facility;

[0013] The high-temperature heat storage medium in the heat storage tank enters the heat storage medium channel of the CO2 adsorption-desorption reactor to heat the reactor. The heated CO2 adsorption-desorption reactor desorbs the adsorbed CO2, and the desorbed CO2 enters the CO2 storage tank for storage, thereby realizing the CO2 desorption process.

[0014] The high-pressure air in the compressed air storage facility enters the air turbine unit, and part of the air after energy release enters the CO2 adsorption-desorption reactor through the bypass to cool the CO2 adsorption-desorption reactor heated during the desorption process, thereby realizing the cooling process of the reactor.

[0015] Preferably, the CO2 adsorption process is in the energy storage stage of the compressed air energy storage system, the CO2 desorption process is between the end of energy storage and the start of energy release of the compressed air energy storage system, and the reactor cooling process is in the energy release stage of the compressed air energy storage system.

[0016] Preferably, when the high-pressure air in the compressed air storage facility enters the air turbine unit, the heat storage medium in the heat recovery system is used to heat the air to improve power generation efficiency.

[0017] Preferably, part of the exhaust gas of the air turbine unit is directly discharged into the atmosphere, and the other part enters the CO2 adsorption-desorption reactor through the bypass for cooling, and the air after the cooling reactor is finally discharged into the atmosphere.

[0018] The air carbon capture system coupled with compressed air energy storage and the capture method thereof provided by the present invention have the following advantages:

[0019] 1. The present invention utilizes the high-pressure air generated by the compression process in the compressed air energy storage system as the air source of the air carbon capture system, reducing the energy consumption and cost of the blower in the traditional direct air carbon capture system; and by increasing the CO2 partial pressure in the air, reducing the energy consumption of the adsorption process.

[0020] 2. The present invention utilizes the compression process in the compressed air energy storage system to remove moisture from the air, effectively reducing the adverse effects of water vapor in the air on the selectivity and adsorption capacity of CO2.

[0021] 3. The present invention uses part of the compression heat recovered during the compression process of the compressed air energy storage system for the desorption process of the air carbon capture system, thereby reducing the energy consumption of CO2 desorption and improving energy utilization efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 A schematic diagram of the composition of an air carbon capture system coupled with compressed air energy storage provided by an embodiment of the present invention;

[0023] In the figure:

[0024] 1-Multi-stage air compression device; 1a-Second-stage air compressor; 1b-Third-stage air compressor; 2-Compressed air storage facility; 3-Air turbine unit; 4-CO2 adsorption-desorption reactor; 5-CO2 storage tank; 6-Heat storage tank; 7-Normal temperature tank. DETAILED DESCRIPTION

[0025] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technical personnel in this field without making creative work are within the scope of protection of the present invention.

[0026] Reference Figure 1 The present invention provides an air carbon capture system coupled with compressed air energy storage, including a compressed air energy storage system, a heat recovery system and an air carbon capture system.

[0027] The compressed air energy storage system includes a multi-stage air compression device 1, a compressed air storage facility 2 and an air turbine unit 3. The multi-stage air compression device has 2-5 single-stage compressors interconnected. In this embodiment, the multi-stage air compression device 1 preferably includes a three-stage compressor for staged air pressurization. An air carbon capture system is installed in series between the second-stage air compressor 1a and the third-stage air compressor 1b of the multi-stage air compression device 1. In this embodiment, the installation and use of the multi-stage air compression device 1 composed of multiple compressors is prior art and will not be elaborated on.

[0028] The air carbon capture system includes a CO2 adsorption-desorption reactor 4 and a CO2 storage tank 5. The CO2 adsorption-desorption reactor 4 is provided with an air channel and a heat storage medium channel. The air channel is filled with a CO2 adsorption material molecular sieve for adsorbing CO2 in the high-pressure air from the multi-stage air compression device 1. The CO2 adsorption material can be a physical adsorbent such as activated carbon and zeolite, or a chemical adsorbent such as solid amine. The air channel inlet of the CO2 adsorption-desorption reactor 4 is connected to the outlet of the second-stage air compressor 1a, and the air channel outlet is connected to the third-stage air compressor 1a through a bypass. The inlet of the air compressor 1b and the inlet of the CO2 storage tank 5 are connected to the atmosphere, and the outlet of the multi-stage air compression device 1 is connected to the inlet of the compressed air storage facility 2, which is used to store high-pressure CO2-poor air; the outlet of the compressed air storage facility 2 is connected to the inlet of the air turbine unit 3, and the outlet of the air turbine unit 3 is connected to the atmosphere, and is connected to the air channel inlet of the CO2 adsorption-desorption reactor 4 through a bypass. In the energy release stage, high-pressure air enters the air turbine unit 3 to generate electricity, and part of the air after energy release is discharged into the atmosphere, and part enters the CO2 adsorption-desorption reactor 4 through a bypass to cool the adsorption material. Several valves are installed between the bypasses of the CO2 adsorption-desorption reactor 4 and the outlet of the air turbine unit 3 for switching, and the operation process of the system is controlled by adjusting the gas flow direction.

[0029] The heat recovery system includes a heat storage tank 6 and a normal temperature tank 7. The inlet of the heat storage tank 6 is connected to the heat storage medium outlets of the multi-stage air compression device 1 and the CO2 adsorption-desorption reactor 4, respectively, for storing the heated heat storage medium and recovering the compression heat generated during the air compression process; the outlet of the heat storage tank 6 is connected to the heat storage medium inlet of the air turbine unit 3 and the CO2 adsorption-desorption reactor 4, respectively, for heating the CO2 adsorption-desorption reactor 4 during the CO2 desorption process and heating the compressed air during the compressed air energy release stage; the inlet of the normal temperature tank 7 is connected to the heat storage medium channel outlet of the air turbine unit 3, and the outlet of the normal temperature tank 7 is connected to the heat storage medium inlet of the multi-stage air compression device 1, for storing the normal temperature heat storage medium after heat exchange; the heat storage medium in the heat storage tank 6 and the normal temperature tank 7 includes but is not limited to water, heat transfer oil or molten salt. In this embodiment, the heat storage medium in the heat recovery system is preferably water.

[0030] The present invention takes an air carbon capture system coupled with 300MW compressed air energy storage with a capture scale of 1000 tons / year as an example, and the working process is as follows:

[0031] The CO2 adsorption process is in the energy storage stage of the compressed air energy storage system. The air is pressurized to 0.7MPa, 5Mpa and 12MPa in three stages through the multi-stage air compression device 1. The CO2 adsorption-desorption reactor 4 arranged between the second-stage air compressor 1a and the third-stage air compressor 1b adsorbs CO2 in the air from the second-stage air compressor 1a. The capture efficiency of the CO2 adsorption-desorption reactor 4 is 60%-70%. The air after CO2 removal enters the third-stage compressor for recompression and is sent to the compressed air storage facility 2 for storage. The heat storage medium in the normal temperature tank 7 enters the multi-stage compression device 1 to recover the compression heat and then enters the heat storage tank 6 to realize heat recovery and storage. The heat storage medium is water, and the heat storage temperature is 180-220℃.

[0032] The CO2 desorption process is between the end of energy storage and the start of energy release in the compressed air energy storage system. The high-temperature heat storage medium in the heat storage tank 6 enters the heat storage medium channel of the CO2 adsorption-desorption reactor 4 to heat the reactor to 80-140°C. After the reactor is heated, the CO2 desorption process will occur, and the desorbed CO2 enters the CO2 storage tank 5 for storage.

[0033] The reactor cooling process is in the energy release stage of the compressed air energy storage system. The high-pressure air in the compressed air storage facility 2 enters the air turbine unit 3, and the heat storage medium in the heat recovery system is used to heat the air to improve the power generation efficiency. The rated power of the unit is 300MW. The exhaust temperature of the air turbine unit 3 is 50°C. Part of the exhaust is directly discharged into the atmosphere, and the other part enters the CO2 adsorption-desorption reactor 4 through a bypass to cool the reactor heated during the desorption process to ensure the normal operation of the reactor in the next adsorption stage. The air after cooling the reactor is finally discharged into the atmosphere.

[0034] The above is only a preferred embodiment of the present invention, and is not any formal or substantial limitation of the present invention. It should be pointed out that ordinary technicians in this technical field can make several improvements and supplements without departing from the present invention, and these improvements and supplements should also be regarded as the protection scope of the present invention. Any technician familiar with this profession, without departing from the spirit and scope of the present invention, can make some changes, modifications and equivalent changes made by using the technical content disclosed above, which are equivalent embodiments of the present invention; at the same time, any changes, modifications and evolutions of any equivalent changes made to the above embodiments based on the essential technology of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. An air carbon capture system coupled with compressed air energy storage, characterized in that: The invention comprises a compressed air energy storage system, a heat recovery system and an air carbon capture system; the compressed air energy storage system comprises a multi-stage air compression device (1), a compressed air storage facility (2) and an air turbine unit (3); the multi-stage air compression device (1) has a plurality of single-stage compressors interconnected with each other; the air carbon capture system comprises a CO2 adsorption-desorption reactor (4) and a CO2 storage tank (5); an air channel and a heat storage medium channel are arranged inside the CO2 adsorption-desorption reactor (4); the heat recovery system comprises a heat storage tank (6) and a normal temperature tank (7); the CO2 adsorption-desorption reactor (4) is arranged between any two-stage compressors of the multi-stage air compression device (1); the air channel inlet of the CO2 adsorption-desorption reactor (4) is connected to the outlet of the compressor of the previous stage; the air channel outlet is connected to the inlet of the compressor of the next stage and the inlet of the CO2 storage tank (5) through a bypass. The outlet of the multi-stage air compression device (1) is connected to the inlet of the compressed air storage facility (2), and the outlet of the compressed air storage facility (2) is connected to the inlet of the air turbine unit (3); the outlet of the air turbine unit (3) is connected to the atmosphere and is connected to the air channel inlet of the CO2 adsorption-desorption reactor (4) through a bypass; the inlet of the heat storage tank (6) is respectively connected to the heat storage medium outlets of the multi-stage air compression device (1) and the CO2 adsorption-desorption reactor (4), and the outlet of the heat storage tank (6) is respectively connected to the heat storage medium inlet of the air turbine unit (3) and the CO2 adsorption-desorption reactor (4); the inlet of the normal temperature tank (7) is connected to the heat storage medium channel outlet of the air turbine unit (3), and the outlet of the normal temperature tank (7) is connected to the heat storage medium inlet of the multi-stage air compression device (1); at least one valve is provided between each of the bypasses for switching.

2. An air carbon capture system coupled with compressed air energy storage as claimed in claim 1, characterized in that: The heat storage medium in the heat storage tank (6) and the normal temperature tank (7) includes, but is not limited to, water, heat transfer oil or molten salt.

3. The air carbon capture system coupled with compressed air energy storage according to claim 1, characterized in that: The multi-stage air compression device (1) comprises a 2-5 stage compressor, and at least one CO2 adsorption-desorption reactor (4) is provided. When multiple CO2 adsorption-desorption reactors (4) are provided, the multiple CO2 adsorption-desorption reactors (4) are arranged between any two stages of compressors that are interconnected; when a single CO2 adsorption-desorption reactor (4) is provided, the CO2 adsorption-desorption reactor (4) is arranged between any two stages of compressors.

4. The air carbon capture system coupled with compressed air energy storage according to claim 1, characterized in that: The air channel of the CO2 adsorption-desorption reactor (4) is filled with CO2 adsorption material, and the CO2 adsorption material can be a physical adsorbent such as activated carbon, zeolite, etc., or a chemical adsorbent such as solid amine.

5. An air carbon capture method coupled with compressed air energy storage, characterized in that: The air carbon capture system coupled with compressed air energy storage as described in any one of claims 1 to 4 is used for capture, comprising the following steps: the multi-stage compression device (1) pressurizes the air in multiple stages, the CO2 adsorption-desorption reactor (4) adsorbs CO2 in the compressed air to realize the CO2 adsorption process, the heat storage tank (6) stores the heat energy generated by the compressed air, and the air from which CO2 is removed is stored through the compressed air storage facility (2); The high-temperature heat storage medium in the heat storage tank (6) enters the heat storage medium channel of the CO2 adsorption-desorption reactor (4) to heat the reactor, and the heated CO2 adsorption-desorption reactor desorbs the adsorbed CO2, and the desorbed CO2 enters the CO2 storage tank (5) for storage, thereby realizing the CO2 desorption process; The high-pressure air in the compressed air storage facility (2) enters the air turbine unit (3), and the air after partially releasing energy enters the CO2 adsorption-desorption reactor (4) through the bypass to cool the CO2 adsorption-desorption reactor heated during the desorption process, thereby realizing the cooling process of the reactor.

6. The air carbon capture method coupled with compressed air energy storage according to claim 5, characterized in that: The CO2 adsorption process is in the energy storage stage of the compressed air energy storage system, the CO2 desorption process is between the end of energy storage and the start of energy release of the compressed air energy storage system, and the reactor cooling process is in the energy release stage of the compressed air energy storage system.

7. The air carbon capture method coupled with compressed air energy storage according to claim 5, characterized in that: When the high-pressure air in the compressed air storage facility (2) enters the air turbine unit (3), the heat storage medium in the heat recovery system is used to heat the air to improve power generation efficiency.

8. The air carbon capture method coupled with compressed air energy storage according to claim 5, characterized in that: Part of the exhaust gas from the air turbine unit (3) is directly discharged into the atmosphere, and the other part enters the CO2 adsorption-desorption reactor (4) through the bypass for cooling. The air after the cooling reactor is finally discharged into the atmosphere.

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