Device and method for capturing and storing carbon dioxide

Abstract

The present invention provides a device and method for capturing and storing carbon dioxide, which belongs to the field of carbon dioxide capture, and includes a flue gas boosting module, a flue gas and liquefied natural gas heat exchange module, a flue gas hydrate generation module, a flue gas hydrate decomposition module, a flue gas hydrate residual gas cooling energy and compression energy recovery module, and a liquid CO 2 Capture module and flue gas hydrate deep-sea storage module. The present invention fully utilizes the cold energy of liquefied natural gas to capture and liquefy carbon dioxide in flue gas, fully utilizes the cold energy of liquefied natural gas to generate flue gas hydrates, and increases the pressure of flue gas and the proportion of carbon dioxide therein through the hydrate method; reduces the compression cost of flue gas and the energy cost of hydrate generation, and the generated flue gas hydrate can be used to capture liquid carbon dioxide through the cold energy of liquefied natural gas, and can also be directly stored in the deep sea.

Description

Technical Field

[0001] The present invention relates to the field of carbon dioxide capture, and in particular to a device and method for capturing and storing carbon dioxide by utilizing liquefied natural gas cold energy coupled with a cryogenic method and a hydrate method. Background Art

[0002] Among carbon capture methods such as liquid absorption, solid adsorption, membrane separation and cryogenic separation, liquefied natural gas (LNG) has huge cold energy. If the cold energy resources can be fully and efficiently utilized to liquefy, separate and seal the carbon dioxide in the flue gas, the cost will be reduced. Summary of the invention

[0003] The purpose of the present invention is to provide a device and method for capturing and storing carbon dioxide by coupling the cold energy of liquefied natural gas with the deep cold method and the hydrate method, so as to make full use of the cold energy of liquefied natural gas to capture and liquefy carbon dioxide in flue gas, make full use of the cold energy of liquefied natural gas to generate flue gas hydrates, and increase the pressure of flue gas and the proportion of carbon dioxide therein by the hydrate method; reduce the compression cost of flue gas and the energy cost of hydrate generation; the generated flue gas hydrates can be used to capture liquid carbon dioxide with the help of liquefied natural gas cold energy, and can also be directly sealed in the deep sea.

[0004] To achieve the above object, the present invention provides the following technical solutions:

[0005] In a first aspect, a method for capturing and storing carbon dioxide using liquefied natural gas cold energy coupled with a cryogenic method and a hydrate method comprises the following steps:

[0006] 1) The flue gas is allowed to enter the flue gas booster module, and the compression energy of the residual gas of the generated flue gas hydrate is used as the driving force. The flue gas is boosted to 2.5-4.0 MPa by boosting, and the flue gas temperature is increased. Then, the boosted flue gas is used to heat the flue gas hydrate to room temperature for decomposition. After the flue gas heat is transferred to the flue gas hydrate and the low-temperature flue gas hydrate to generate the residual gas, the high-pressure flue gas is mixed with the flue gas hydrate decomposition gas and transported to the flue gas and liquefied natural gas heat exchange module.

[0007] 2) The liquefied natural gas is gasified and heated to 10-15°C for external transmission through the flue gas and liquefied natural gas heat exchange module, and the high-pressure flue gas is cooled to -75--70°C, so that part of the carbon dioxide is liquefied and flows out of the heat exchanger and into the liquid carbon dioxide capture module, and the remaining high-pressure and low-temperature flue gas is transported to the flue gas hydrate generation module.

[0008] 3) The flue gas hydrate generation module uses the cold energy absorbed from liquefied natural gas to directly generate flue gas hydrates, avoiding the additional cold energy required for capturing carbon dioxide in flue gas by conventional flue gas hydrate method, thus reducing the cost of flue gas hydrate generation. The valve contained in the flue gas hydrate generation module regulates the flow direction of high-pressure and low-temperature flue gas, and can switch with the flue gas hydrate decomposition module to capture flue gas with high concentration of carbon dioxide, and transport the residual gas generated by high-pressure and low-temperature flue gas hydrate to the flue gas hydrate residual gas cold energy and compression energy recovery module. After the flue gas hydrate generation is completed, some flue gas hydrate containers use compressed flue gas to heat and decompose flue gas hydrates, and the flue gas hydrate generation module is transformed into a flue gas hydrate decomposition module. The remaining flue gas hydrate containers can be transferred to ships, transported to the sea, and directly transformed into flue gas hydrate deep-sea storage modules.

[0009] 4) The flue gas hydrate decomposition module is transformed from part of the container of the flue gas hydrate generation module. It absorbs heat energy from the compressed flue gas to decompose the flue gas hydrate into high-pressure and high-concentration carbon dioxide flue gas, and mixes the high-pressure and high-concentration carbon dioxide flue gas with the initial compressed flue gas to increase the flue gas pressure and carbon dioxide ratio, and transports it to the flue gas and liquefied natural gas heat exchange module to increase the carbon dioxide liquefaction rate.

[0010] 5) The flue gas hydrate residual gas cooling energy and compression energy recovery module is used to pre-cool the pressurized flue gas, and then enter the power drive system of the pressurized flue gas to drive the compressor to pressurize the initial flue gas, thereby reducing the flue gas compression energy and cooling energy loss.

[0011] 6) The liquid CO2 capture module captures the liquid carbon dioxide flowing out of the flue gas and liquefied natural gas heat exchange module and stores the liquid carbon dioxide.

[0012] Secondly, a device for capturing and storing carbon dioxide using liquefied natural gas cold energy coupled with cryogenic method and hydrate method includes a flue gas boosting module, a flue gas and liquefied natural gas heat exchange module, a flue gas hydrate generation module and a flue gas hydrate decomposition module, a module for recovering the residual gas cold energy and compression energy of generated flue gas hydrates, and a liquid CO2 capture module.

[0013] The flue gas boosting module comprises a part of the inner casing of the flue gas hydrate generation and decomposition container group and a flue gas compressor, wherein the flue gas compressor is connected to the flue gas flow pipeline and is connected to one end of the part of the inner casing of the flue gas hydrate generation and decomposition container group.

[0014] The flue gas and liquefied natural gas heat exchange module includes a check valve, an electric three-way valve, a flue gas and liquefied natural gas heat exchanger, a liquefied natural gas booster pump and a natural gas compressor. The check valve is connected to the electric three-way valve, the electric three-way valve is connected to the flue gas and liquefied natural gas heat exchanger, and the flue gas and liquefied natural gas heat exchanger is connected to the liquefied natural gas booster pump and the natural gas compressor.

[0015] The flue gas hydrate generation module and the flue gas hydrate decomposition module include some containers of the flue gas hydrate generation and decomposition container group, some containers of the flue gas hydrate generation and decomposition container group are connected to the flue gas and liquefied natural gas heat exchanger, and some containers of the flue gas hydrate generation and decomposition container group are connected to the electric three-way valve.

[0016] The module for recovering cooling energy and compression energy of residual gas for generating flue gas hydrates comprises a flue gas and flue gas residual gas heat exchanger, which is connected to the other end of the inner sleeve of some containers of the flue gas hydrate generating and decomposing container group, and is connected to the check valve and all the internal containers of the flue gas hydrate generating and decomposing container group.

[0017] The liquid CO2 capture module comprises a cryogenic liquid carbon dioxide pump and a liquid carbon dioxide container. The cryogenic liquid carbon dioxide pump is connected to a flue gas and liquefied natural gas heat exchanger, and the liquid carbon dioxide container is connected to the cryogenic liquid carbon dioxide pump.

[0018] Furthermore, the flue gas hydrate deep-sea storage module includes the remaining containers of the flue gas hydrate generation and decomposition container group and a flue gas hydrate container transport ship. The remaining containers of the flue gas hydrate generation and decomposition container group are connected to the flue gas and liquefied natural gas heat exchanger, and the remaining containers of the flue gas hydrate generation and decomposition container group can be transferred on the flue gas hydrate container transport ship.

[0019] Advantages of the present invention:

[0020] 1. Utilize the cold energy of liquefied natural gas, couple the cryogenic method and the hydrate method to capture liquid carbon dioxide in flue gas, reduce the cost of cold energy, and increase the carbon dioxide capture rate.

[0021] 2. Use liquefied natural gas cold energy to generate flue gas hydrates on the coast, and transport the flue gas hydrate containers to the deep sea for storage by ship, thereby improving the speed and efficiency of flue gas storage and avoiding problems such as carbon dioxide leakage.

[0022] 3. Use flue gas residual gas to pre-cool the initial flue gas to reduce the cost of cold energy, use liquefied natural gas cold energy to generate flue gas hydrates, then absorb heat from the air and decompose, convert the liquefied natural gas cold energy into flue gas compression energy, use flue gas residual gas to pressurize the initial flue gas, and reduce the cost of electric supercharging flue gas compression. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 A schematic diagram of the structure of a device for capturing carbon dioxide using liquefied natural gas cold energy coupled with a cryogenic method and a hydrate method provided by the present invention;

[0024] Figure 2A schematic diagram of the structure of a device for capturing and storing carbon dioxide using liquefied natural gas cold energy coupled with a cryogenic method and a hydrate method provided by the present invention;

[0025] Figure 3 A system flow chart of a device for capturing and storing carbon dioxide provided by the present invention;

[0026] In the figure: 1. Flue gas compressor, 2. Flue gas hydrate generation and decomposition container group, 3. Flue gas and flue gas residual gas heat exchanger, 4. Check valve, 5. Electric three-way valve, 6. Flue gas and liquefied natural gas heat exchanger, 7. Low-temperature liquid carbon dioxide pump, 8. Liquid carbon dioxide container, 9. Liquefied natural gas booster pump, 10. Natural gas compressor, 11. Flue gas hydrate container transport ship. DETAILED DESCRIPTION

[0027] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention.

[0028] like Figure 3 As shown, a method for capturing and storing carbon dioxide by coupling the cold energy of liquefied natural gas with the cryogenic method and the hydrate method comprises the following steps:

[0029] 1) The flue gas is allowed to enter the flue gas booster module, and the compression energy of the residual gas of the generated flue gas hydrate is used as the driving force. The flue gas is boosted to 2.5-4.0 MPa by boosting, and the flue gas temperature is increased. Then, the boosted flue gas is used to heat the flue gas hydrate to room temperature for decomposition. After the flue gas heat is transferred to the flue gas hydrate and the low-temperature flue gas hydrate to generate the residual gas, the high-pressure flue gas is mixed with the flue gas hydrate decomposition gas and transported to the flue gas and liquefied natural gas heat exchange module.

[0030] 2) The liquefied natural gas is gasified and heated to 10-15°C for external transmission through the flue gas and liquefied natural gas heat exchange module, and the high-pressure flue gas is cooled to -75--70°C, so that part of the carbon dioxide is liquefied and flows out of the heat exchanger and into the liquid carbon dioxide capture module, and the remaining high-pressure and low-temperature flue gas is transported to the flue gas hydrate generation module.

[0031] 3) The flue gas hydrate generation module uses the cold energy absorbed from liquefied natural gas to directly generate flue gas hydrates, avoiding the additional cold energy required for capturing carbon dioxide in flue gas by conventional flue gas hydrate method, thus reducing the cost of flue gas hydrate generation. The valve contained in the flue gas hydrate generation module regulates the flow direction of high-pressure and low-temperature flue gas, and can switch with the flue gas hydrate decomposition module to capture flue gas with high concentration of carbon dioxide, and transport the residual gas generated by high-pressure and low-temperature flue gas hydrate to the flue gas hydrate residual gas cold energy and compression energy recovery module. After the flue gas hydrate generation is completed, some flue gas hydrate containers use compressed flue gas to heat and decompose flue gas hydrates, and the flue gas hydrate generation module is transformed into a flue gas hydrate decomposition module. The remaining flue gas hydrate containers are transferred to ships, transported to the sea, and transformed into flue gas hydrate deep-sea storage modules.

[0032] 4) The flue gas hydrate decomposition module is transformed from part of the container of the flue gas hydrate generation module. It absorbs heat energy from the compressed flue gas to decompose the flue gas hydrate into high-pressure and high-concentration carbon dioxide flue gas, and mixes the high-pressure and high-concentration carbon dioxide flue gas with the initial compressed flue gas to increase the flue gas pressure and carbon dioxide ratio, and transports it to the flue gas and liquefied natural gas heat exchange module to increase the carbon dioxide liquefaction rate.

[0033] 5) The flue gas hydrate residual gas cooling energy and compression energy recovery module is used to pre-cool the pressurized flue gas, and then enter the power drive system of the pressurized flue gas to drive the compressor to pressurize the initial flue gas, thereby reducing the flue gas compression energy and cooling energy loss.

[0034] 6) The liquid CO2 capture module captures the liquid CO2 flowing out of the flue gas and liquefied natural gas heat exchange module and stores the liquid CO2.

[0035] As a preferred embodiment of the present invention, the flue gas hydrate deep-sea storage module is transformed from a partial container of the flue gas hydrate generation module, which is first transferred to a ship by a crane and then transported to the deep sea surface. The flue gas hydrate container has certain pressure resistance and thermal insulation properties, and the overall density is higher than that of seawater. The internal flue gas hydrate temperature is about -30°C. During the process of sinking to more than 1,000 meters below the seabed, the temperature of the flue gas hydrate gradually increases to 2-4°C. Since the container has a certain elasticity, the internal pressure of the container gradually increases from an initial pressure of about 4MPa to the seabed pressure, and the pressure difference between the inside and outside of the container gradually decreases from 4MPa to about 0MPa.

[0036] The remaining flue gas hydrates generated are not used to capture liquid carbon dioxide, some flue gas hydrate generation containers do not contain flue gas casings, and the remaining flue gas hydrate containers are directly transported to the sea by ship 11, and then directly put into the deep seabed for sealing; compared with the initial flue gas transported by pipeline, the proportion of carbon dioxide in the flue gas hydrates is increased, which greatly reduces the transportation cost of unit mass of carbon dioxide; compared with liquid carbon dioxide, hydrates are generated on the deep seabed to prevent the leakage of carbon dioxide, solve the problem of slow generation rate of flue gas hydrates on the seabed, and avoid the compression energy required to transport liquid carbon dioxide to the seabed.

[0037] like Figure 1 and Figure 2 As shown, based on the above-mentioned method for capturing and storing carbon dioxide by coupling the cold energy of liquefied natural gas with the cryogenic method and the hydrate method, the present invention also proposes a device for capturing and storing carbon dioxide by coupling the cold energy of liquefied natural gas with the cryogenic method and the hydrate method, including a flue gas boosting module, a flue gas and liquefied natural gas heat exchange module, a flue gas hydrate generation module and a flue gas hydrate decomposition module, a module for recovering the cold energy and compression energy of the residual gas generated by the flue gas hydrate, and a liquid CO2 capture module.

[0038] The flue gas boosting module includes a partial container inner sleeve of the flue gas hydrate generation and decomposition container group 2 and a flue gas compressor 1, wherein the flue gas compressor 1 is connected to a flue gas inlet pipeline and is connected to one end of a partial container inner sleeve of the flue gas hydrate generation and decomposition container group 2.

[0039] The flue gas and liquefied natural gas heat exchange module includes a check valve 4, an electric three-way valve 5, a flue gas and liquefied natural gas heat exchanger 6, a liquefied natural gas booster pump 9 and a natural gas compressor 10. The check valve 4 is connected to the electric three-way valve 5, the electric three-way valve 5 is connected to the flue gas and liquefied natural gas heat exchanger 6, and the flue gas and liquefied natural gas heat exchanger 6 is connected to the liquefied natural gas booster pump 9 and the natural gas compressor 10.

[0040] The flue gas hydrate generation module and the flue gas hydrate decomposition module include some containers of the flue gas hydrate generation and decomposition container group 2, and some containers of the flue gas hydrate generation and decomposition container group 2 are connected to the flue gas and liquefied natural gas heat exchanger 6, and some containers of the flue gas hydrate generation and decomposition container group 2 are connected to the electric three-way valve 5.

[0041] The flue gas hydrate generating residual gas cooling energy and compression energy recovery module includes a flue gas and flue gas residual gas heat exchanger 3, and the flue gas and flue gas residual gas heat exchanger 3 is connected to the other end of the inner sleeve of some containers of the flue gas hydrate generating and decomposing container group 2, and the flue gas and flue gas residual gas heat exchanger 3 is connected to the check valve 4 and all the internal containers of the flue gas hydrate generating and decomposing container group 2.

[0042] The liquid CO2 capture module comprises a cryogenic liquid carbon dioxide pump 7 and a liquid carbon dioxide container 8 . The cryogenic liquid carbon dioxide pump 7 is connected to the flue gas and liquefied natural gas heat exchanger 6 , and the liquid carbon dioxide container 8 is connected to the cryogenic liquid carbon dioxide pump 7 .

[0043] As a preferred embodiment of the present invention, the flue gas hydrate deep-sea storage module includes the remaining containers of the flue gas hydrate generation and decomposition container group 2 and a flue gas hydrate container transport ship 11. The remaining containers of the flue gas hydrate generation and decomposition container group 2 are connected to the flue gas and liquefied natural gas heat exchanger 6, and the remaining containers of the flue gas hydrate generation and decomposition container group 2 can be transferred on the flue gas hydrate container transport ship 11.

[0044] The sum of the ratios of nitrogen and oxygen in coal-fired flue gas is as high as over 84%, and the ratio of carbon dioxide is about 16%. After software and experimental analysis, it was found that under a pressure of 0.4 MPa, the temperature dropped to -96°C, and carbon dioxide began to liquefy and separate. When the temperature dropped to -120°C, the carbon dioxide liquefaction ratio reached 90.9%. At this time, carbon dioxide would solidify on the inner wall of the heat exchanger and could not flow out, and continuous separation could not be achieved. Therefore, the flue gas needs to be pressurized to 4 MPa, and the temperature drops to -62℃, carbon dioxide begins to liquefy. Under the conditions of 4MPa and -75℃, the liquefied proportion of carbon dioxide in the flue gas reaches 48.1%. At this time, liquid carbon dioxide can flow out continuously, and the temperature of the flue gas flowing out of the heat exchanger is lower than -70℃, and the pressure is higher than 3.5MPa. Flue gas hydrates are directly generated by the high-pressure and low-temperature flue gas flowing out of the heat exchanger. Compared with the conventional flue gas hydrate method to capture carbon dioxide in flue gas, the cost of cold energy is saved. Compared with the ordinary liquefied natural gas cold energy method to capture carbon dioxide in flue gas, carbon dioxide is captured twice, and the carbon dioxide in the flue gas is accumulated in the flue gas hydrate. According to experimental analysis, the proportion of carbon dioxide in the flue gas in the flue gas hydrate decomposition gas is increased to about 50%, the pressure is higher than 4MPa, the temperature is about 10℃, and it is mixed with the initial pressurized flue gas to increase the pressure and carbon dioxide ratio of the flue gas, and effectively improve the carbon dioxide liquefaction rate. According to software and experimental analysis, when the proportion of carbon dioxide in the flue gas is 50%, the carbon dioxide liquefaction ratio reaches 90.1% under 4MPa and -75℃.

[0045] After the generation of flue gas hydrates, the ratio of nitrogen and oxygen in the residual flue gas increases to about 95%, the temperature is about -30°C, and the pressure is about 2MPa. The cold energy of the residual flue gas after the generation of flue gas hydrates is used to pre-cool the high-temperature flue gas after the compressor is pressurized, thereby improving the utilization rate of cold energy and reducing the cost of cold energy. The compression energy of the flue gas is then used to drive the flue gas secondary compressor, thereby reducing the energy consumption cost of the compressor.

[0046] The steps of capturing and storing carbon dioxide using a device that uses liquefied natural gas cold energy coupled with a cryogenic method and a hydrate method to capture and store carbon dioxide are as follows:

[0047] 1) The flue gas first flows through the flue gas compressor 1 for pressurization, and then flows through the inner sleeve of some containers of the flue gas hydrate generation and decomposition container group 2 to heat and decompose the flue gas hydrate. The flue gas temperature is reduced to about room temperature, and then pre-cooled to about 10°C through the flue gas and flue gas residual gas heat exchanger 3.

[0048] 2) After the pressurized pre-cooled flue gas flows through the check valve 4 and the electric three-way valve 5, it is mixed with the flue gas decomposed from the flue gas hydrate to increase the flue gas pressure and carbon dioxide ratio, and then enters the flue gas and liquefied natural gas heat exchanger 6 to exchange heat with the liquefied natural gas. At the same time, the liquefied natural gas is pressurized by the liquefied natural gas booster pump 9 and enters the flue gas and liquefied natural gas heat exchanger 6 to cool the flue gas. Then the gasified natural gas enters the natural gas compressor 10 to be pressurized and transmitted to the natural gas pipeline system. After the liquefied natural gas is cooled, part of the carbon dioxide in the flue gas is liquefied, and the remaining flue gas is cooled to about -75°C.

[0049] 3) The high-pressure and low-temperature flue gas flowing out of the flue gas and liquefied natural gas heat exchanger 6 enters part of the containers of the flue gas hydrate generation and decomposition container group 2 in turn to generate flue gas hydrates. During the generation of flue gas hydrates, the residual flue gas of the generated flue gas hydrates enters the cooling energy and compression energy recovery module of the generated flue gas hydrate residual gas. After the generation of flue gas hydrates is completed, part of the flue gas hydrate containers are transformed into flue gas hydrate decomposition modules, which absorb heat from the compressed flue gas and decompose high-pressure and high-concentration carbon dioxide flue gas, which flows into the electric three-way valve 5 to mix with the initial flue gas to increase the flue gas pressure and carbon dioxide ratio, and then enters the flue gas and liquefied natural gas heat exchanger 6 again to capture liquid carbon dioxide for the second time and improve the carbon dioxide capture rate.

[0050] 4) Some containers of the flue gas hydrate generation and decomposition container group 2 do not contain flue gas inner casings. After the flue gas hydrate is generated in the container, it is not converted into a flue gas hydrate decomposition module, but is directly transferred to the ship and transported to the sea by the ship 11. Then the container is directly dropped to the seabed for deep-sea storage.

[0051] 5) Generation of flue gas hydrates The residual flue gas first passes through the flue gas and flue gas residual gas heat exchanger 3 to pre-cool the compressed flue gas and raise the temperature to 10° C., and then enters the power drive system of the flue gas compressor 1 to provide kinetic energy for the pressurized flue gas, and is finally transported to the flue gas discharge pipeline.

[0052] 6) Liquid carbon dioxide flows out from the first flue gas and liquefied natural gas heat exchanger 6, is pressurized by the first low-temperature liquid carbon dioxide pump 7, and is injected into the first liquid carbon dioxide container 8 for storage.

[0053] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art can still adjust the technical solutions described in the above embodiments or replace some of the technical features by equivalents. Therefore, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalent technologies, the present invention is also intended to include these modifications and variations.

Claims

1. A method for capturing and storing carbon dioxide by coupling the cold energy of liquefied natural gas with the cryogenic method and the hydrate method, characterized in that: The following steps are involved: 1) The flue gas is first pressurized, and then used to heat the flue gas hydrate to room temperature for decomposition, and then the flue gas heat is transferred to the residual flue gas, and finally it is mixed with the flue gas hydrate decomposition gas and transported to the flue gas and liquefied natural gas heat exchange module; 2) The flue gas and liquefied natural gas heat exchange module gasifies the liquefied natural gas and heats it up for external transmission, and uses it to cool down the high-pressure flue gas, so that part of the carbon dioxide is liquefied and flows into the liquid carbon dioxide capture module, and the remaining flue gas is transported to the flue gas hydrate generation module; 3) After the flue gas absorbs cold energy from the liquefied natural gas, flue gas hydrates are directly generated, and the residual flue gas is transported to the residual flue gas cold energy and compression energy recovery module. After the generation of some flue gas hydrates is completed, it is transformed into a flue gas hydrate decomposition module; 4) Flue gas hydrate decomposes into flue gas with high pressure and high concentration of carbon dioxide, which is then mixed with the initial pressurized flue gas to increase the carbon dioxide liquefaction rate; 5) The residual flue gas pre-cools the pressurized flue gas, and then drives the compressor to pressurize the initial flue gas, reducing the flue gas compression energy and cooling energy loss; 6) Part of the liquid CO2 flows out from the flue gas through heat exchange with liquefied natural gas and is stored; After the remaining flue gas hydrates in step 3) are generated, the flue gas hydrate container is transported to the sea by ship and then directly put into the deep seabed for sealing.

2. A device for capturing and storing carbon dioxide by coupling the cold energy of liquefied natural gas with the cryogenic method and the hydrate method, characterized in that include: A flue gas boosting module, comprising a portion of the inner casing of a flue gas hydrate generation and decomposition container group (2) and a flue gas compressor (1), wherein the flue gas compressor (1) is connected to a flue gas inflow pipeline, and the flue gas compressor (1) is connected to one end of the portion of the inner casing of the container of the flue gas hydrate generation and decomposition container group (2); A flue gas and liquefied natural gas heat exchange module, comprising a check valve (4), an electric three-way valve (5), a flue gas and liquefied natural gas heat exchanger (6), a liquefied natural gas booster pump (9) and a natural gas compressor (10), wherein the check valve (4) is connected to the electric three-way valve (5), the electric three-way valve (5) is connected to the flue gas and liquefied natural gas heat exchanger (6), and the flue gas and liquefied natural gas heat exchanger (6) is connected to the liquefied natural gas booster pump (9) and the natural gas compressor (10); A flue gas hydrate generation module and a flue gas hydrate decomposition module, comprising a partial container of a flue gas hydrate generation and decomposition container group (2), wherein the partial container of the flue gas hydrate generation and decomposition container group (2) is connected to a flue gas and liquefied natural gas heat exchanger (6), and the partial container of the flue gas hydrate generation and decomposition container group (2) is connected to an electric three-way valve (5); A module for recovering cooling energy and compression energy of flue gas hydrate residual gas, comprising a flue gas and flue gas residual gas heat exchanger (3), wherein the flue gas and flue gas residual gas heat exchanger (3) is connected to the other end of the inner sleeve of some containers of the flue gas hydrate generation and decomposition container group (2), and the flue gas and flue gas residual gas heat exchanger (3) is connected to the check valve (4) and all containers inside the flue gas hydrate generation and decomposition container group (2); A liquid CO2 capture module, comprising a cryogenic liquid carbon dioxide pump (7) and a liquid carbon dioxide container (8), wherein the cryogenic liquid carbon dioxide pump (7) is connected to a flue gas and liquefied natural gas heat exchanger (6), and the liquid carbon dioxide container (8) is connected to the cryogenic liquid carbon dioxide pump (7); It also includes a flue gas hydrate deep-sea storage module, which includes the remaining containers of the flue gas hydrate generation and decomposition container group (2) and a flue gas hydrate container transport ship (11), the remaining containers of the flue gas hydrate generation and decomposition container group (2) are connected to the flue gas and liquefied natural gas heat exchanger (6), and the remaining containers of the flue gas hydrate generation and decomposition container group (2) can be transferred on the flue gas hydrate container transport ship (11).

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