A novel oxy-fuel combustion carbon capture system for LNG ships

Abstract

The present invention discloses a novel oxy-fuel combustion carbon capture system for LNG ships, belonging to the field of carbon capture for LNG ships. It includes a carbon dioxide collection area, and also includes an LNG cold energy air separation area and an oxy-fuel combustion area. The LNG cold energy air separation area and the oxy-fuel combustion area are respectively connected to the carbon dioxide collection area for realizing carbon capture on LNG ships. The present invention realizes carbon capture for LNG ships through LNG cold energy air separation technology, oxy-fuel combustion technology and electrolytic seawater technology. The present invention utilizes the cold energy in the liquid oxygen of the LNG air separation product to liquefy and collect carbon dioxide in the flue gas, making full use of the LNG cold energy, which is beneficial to improving the energy utilization efficiency. The present invention uses oxy-fuel combustion technology to make the flue gas obtained by the gas turbine contain only carbon dioxide and water, and realizes carbon dioxide capture in a simple way, reducing the carbon capture cost of the system.

Description

Technical Field

[0001] The present invention relates to a novel oxy-fuel combustion carbon capture system for LNG ships, belonging to the field of carbon capture for LNG ships. Background Art

[0002] With the continuous growth of the world's population, the demand for primary energy by humans is also increasing. During the development and utilization of primary energy, a large amount of carbon dioxide emissions cause the greenhouse effect, which will lead to global warming and threaten the survival and development of humanity. Therefore, reducing carbon dioxide emissions has become an important issue that people urgently need to solve at present.

[0003] In global trade, maritime transportation accounts for two-thirds of the total global trade volume. The carbon emissions caused by maritime transportation every year are equivalent to those of the eighth largest carbon-emitting country in the world. In the field of ships, LNG is considered a transitional fuel from fossil fuels to hydrogen fuels. As a clean primary energy, LNG has the advantages of clean combustion products and high combustion efficiency. Before combustion, LNG needs to be gasified, and a large amount of high-grade cold energy is wasted during this process. If this cold energy can be recycled, it will bring high economic benefits. In LNG ships, the rational allocation of cold and thermal energy is currently a hot topic of concern.

[0004] In the patent document with the authorization publication number CN111874200A, a comprehensive thermal energy utilization system for LNG ships is proposed. This system uses the cooling water of the LNG engine to heat and convert LNG into CNG to achieve LNG gasification. At the same time, the waste heat of the flue gas is used for seawater desalination to achieve comprehensive energy utilization. However, this system does not consider capturing the carbon dioxide emitted by the ship.

[0005] In the patent document with the authorization publication number CN115263466A, a low-temperature carbon capture coupling cold energy and preheating cascade utilization system for LNG-powered ships is proposed. Through the organic Rankine cycle and seawater, LNG is converted into NG, and at the same time, the cold energy of the products of the air separation technology is used for carbon capture and air separation. The high-grade cold energy of LNG in this system is utilized by the two-stage cascaded Rankine cycle, and the cold energy required by the air separation device comes from the air separation products. In this system, the cold energy air separation device only realizes the separation of oxygen in the air, and the separated nitrogen is discharged after providing the cold energy, without using it as a by-product of the system.

[0006] In the patent document with the authorization publication number CN 115540498 A, a device for utilizing cold and heat energy and a method for carbon capture suitable for LNG ships are proposed. In this device, by reasonably matching the cold and heat sources on the LNG ship, carbon dioxide capture is achieved through an absorption carbon capture system, and the cold energy of LNG provides cold energy for liquefied storage of carbon dioxide. However, the pressure for liquefied storage of carbon dioxide in this system is relatively high.

[0007] In combination with the existing technical conditions and some deficiencies in the above several inventions, the present invention proposes a new type of oxy-fuel combustion carbon capture system for LNG ships to solve the above problems, which is very necessary. Summary of the Invention

[0008] Aiming at the technical problems mentioned in the above background art, the present invention aims to make full use of high-grade cold energy by using LNG cold energy air separation technology to provide oxygen for oxy-fuel combustion carbon capture. At the same time, the cold energy obtained from air separation is used to liquefy and store carbon dioxide. The following technical solutions are specifically adopted to achieve this:

[0009] A new type of oxy-fuel combustion carbon capture system for LNG ships includes a carbon dioxide collection area, and also includes an LNG cold energy air separation area and an oxy-fuel combustion area. The LNG cold energy air separation area and the oxy-fuel combustion area are respectively connected to the carbon dioxide collection area for realizing carbon capture on LNG ships.

[0010] Preferably, it further includes an electrolytic seawater oxygen production area. One end of the electrolytic seawater oxygen production area is connected to the oxy-fuel combustion area for supplying oxygen to the oxy-fuel combustion area by the oxygen produced by the electrolytic seawater oxygen production area. The dioxide collection area is electrically connected to the electrolytic seawater oxygen production area for supplying power to the electrolytic seawater oxygen production area through the carbon dioxide collection area.

[0011] Preferably, the carbon dioxide collection area includes a precooler, an air cooler, a water storage tank, a water-cooled separator, a liquefier, a carbon dioxide storage tank, an air heater, an expander, and a generator;

[0012] The tube-side inlet of the precooler is connected to the LNG cold energy air separation area through a pipeline; the tube-side outlet of the precooler is connected to the oxy-fuel combustion area through a pipeline; the shell-side outlet of the precooler is connected to the air cooler through a pipeline; the outlet of the air cooler is connected to the water-cooled separator through a pipeline; the liquid outlet of the water-cooled separator is connected to the water storage tank through a pipeline; the carbon dioxide outlet of the water-cooled separator is connected to the tube-side inlet of the liquefier and the oxy-fuel combustion area through a pipeline; the tube-side outlet of the liquefier is connected to the carbon dioxide storage tank through a pipeline; the LNG cold energy air separation area is connected to the shell-side inlet of the liquefier through a pipeline, and the shell-side outlet of the liquefier is connected to the air heater through a pipeline; the outlet of the air heater is connected to the inlet of the expander through a pipeline, and the outlet of the expander is connected to the oxy-fuel combustion area through a pipeline; the output end of the expander is connected to the generator, and the generator is electrically connected to the electrolytic seawater oxygen production area.

[0013] Preferably, the LNG cold energy air separation area includes an air filter, an air compressor, an air precooler, a cryogenic heat exchanger, a liquid oxygen storage tank, a high-low pressure separation tower, a liquid nitrogen storage tank, an argon purifier, an argon purification tower, a liquid argon storage tank, a circulating nitrogen compressor, an LNG heat exchanger, and a nitrogen throttle valve;

[0014] The outlet of the air filter is connected to the inlet of the air compressor through a pipeline; the outlet of the air compressor is connected to the inlet of the air pre-cooler through a pipeline; the inlet of the air pre-cooler is connected to the air inlet of the low-temperature heat exchanger through a pipeline; the air outlet of the low-temperature heat exchanger is connected to the air inlet of the high-low pressure separation column through a pipeline; the liquid oxygen outlet of the high-low pressure separation column is connected to the liquid oxygen storage tank through a pipeline; the liquid nitrogen outlet of the high-low pressure separation column is connected to the liquid nitrogen storage tank through a pipeline; the liquid argon-containing outlet of the high-low pressure separation column is connected to the inlet of the argon purifier through a pipeline; the outlet of the argon purifier is connected to the inlet of the argon purification column through a pipeline, and the argon purification column is connected to the liquid argon storage tank through a pipeline;

[0015] The waste nitrogen outlet of the high-low pressure separation column is connected to the waste nitrogen inlet of the low-temperature heat exchanger through a pipeline; LNG enters the LNG inlet of the LNG heat exchanger; the high-pressure circulating nitrogen secondary condensation outlet of the LNG heat exchanger is connected to the inlet of the nitrogen throttle valve through a pipeline; the outlet of the nitrogen throttle valve is connected to the circulating liquid nitrogen inlet of the high-low pressure separation column through a pipeline; the circulating gas nitrogen outlet of the high-low pressure separation column is connected to the circulating nitrogen inlet of the low-temperature heat exchanger through a pipeline; the circulating nitrogen outlet of the low-temperature heat exchanger is connected to the circulating nitrogen inlet of the LNG heat exchanger through a pipeline; the circulating nitrogen outlet of the LNG heat exchanger is connected to the inlet of the circulating nitrogen compressor through a pipeline; the outlet of the circulating nitrogen compressor is connected to the high-pressure circulating nitrogen primary condensation inlet of the LNG heat exchanger through a pipeline; the high-pressure circulating nitrogen primary condensation outlet of the LNG heat exchanger is connected to the high-pressure circulating nitrogen secondary condensation inlet of the LNG heat exchanger through a pipeline;

[0016] The LNG outlet of the LNG heat exchanger is connected to the tube side inlet of the pre-cooler through a pipeline; the outlet of the liquid oxygen storage tank is connected to the shell side inlet of the liquefier through a pipeline.

[0017] Preferably, the oxygen-enriched combustion zone includes a gas turbine and a mixer, wherein: the outlet of the mixer is connected to the gas inlet of the gas turbine through a pipeline; the oxygen inlet of the mixer is connected to the outlet of the expander through a pipeline, the carbon dioxide inlet of the mixer is connected to the carbon dioxide outlet of the water-cooling separator through a pipeline, and the fuel inlet of the gas turbine is connected to the tube side outlet of the pre-cooler through a pipeline; the flue gas outlet of the gas turbine is connected to the shell side inlet of the pre-cooler through a pipeline.

[0018] Preferably, the electrolytic seawater oxygen production area includes an electrolyzer, a hydrogen storage tank, and an oxygen storage tank. The generator is electrically connected to the electrolyzer to supply the electrical energy generated by the generator to the electrolyzer. The oxygen outlet of the electrolyzer is connected to the oxygen storage tank through a pipeline. The oxygen storage tank is connected to the oxygen inlet of the mixer through a pipeline. The hydrogen outlet of the electrolyzer is connected to the hydrogen storage tank through a pipeline.

[0019] The beneficial effects of the present invention are as follows:

[0020] 1. The present invention realizes carbon capture for LNG ships through LNG cold energy air separation technology, oxy-fuel combustion technology, and electrolytic seawater technology.

[0021] 2. The present invention utilizes the cold energy in the liquid oxygen, which is a product of LNG air separation, to liquefy and collect carbon dioxide in the flue gas, making full use of the LNG cold energy and facilitating the improvement of energy utilization efficiency.

[0022] 3. The present invention uses oxy-fuel combustion technology to make the flue gas obtained by the gas turbine contain only carbon dioxide and water, and realizes carbon dioxide capture through a simple method, reducing the system carbon capture cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 is a schematic flow diagram of the present invention;

[0024] Figure 2 is a schematic diagram of each interface of the low-temperature heat exchanger;

[0025] Figure 3 is a schematic diagram of each interface of the LNG heat exchanger;

[0026] In the figure: air filter 1; air compressor 2; air precooler 3; low-temperature heat exchanger 4; liquid oxygen storage tank 5; high-low pressure separation tower 6; liquid nitrogen storage tank 7; argon purifier 8; argon purification tower 9; liquid argon storage tank 10; circulating nitrogen compressor 11; LNG heat exchanger 12; nitrogen throttle valve 13; precooler 14; air cooler 15; water storage tank 16; water cooling separator 17; liquefier 18; carbon dioxide storage tank 19; air heater 20; expander 21; generator 22; mixer 23; gas turbine 24; hydrogen storage tank 25; electrolyzer 26; oxygen storage tank 27. DETAILED DESCRIPTION OF THE INVENTION

[0027] In order to facilitate the understanding of the technical means, creative features, achieved purposes, and effects of the present invention, the present invention will be further described below with reference to specific drawings.

[0028] As Figure 1As shown in the figure, a novel oxy-fuel combustion carbon capture system for LNG ships includes a carbon dioxide collection area, and also includes an LNG cold energy air separation area and an oxy-fuel combustion area. The LNG cold energy air separation area and the oxy-fuel combustion area are respectively connected to the carbon dioxide collection area to achieve carbon capture on LNG ships.

[0029] It also includes an electrolytic seawater oxygen production area. One end of the electrolytic seawater oxygen production area is connected to the oxy-fuel combustion area to supply oxygen to the oxy-fuel combustion area through the oxygen produced by the electrolytic seawater oxygen production area. The dioxide collection area is electrically connected to the electrolytic seawater oxygen production area to supply power to the electrolytic seawater oxygen production area through the carbon dioxide collection area.

[0030] The carbon dioxide collection area includes a pre-cooler 14, an air cooler 15, a water storage tank 16, a water-cooling separator 17, a liquefier 18, a carbon dioxide storage tank 19, an air heater 20, an expander 21, and a generator 22;

[0031] The tube-side inlet of the pre-cooler 14 is connected to the LNG cold energy air separation area through a pipeline; the tube-side outlet of the pre-cooler 14 is connected to the oxy-fuel combustion area through a pipeline; the shell-side outlet of the pre-cooler 14 is connected to the air cooler 15 through a pipeline; the outlet of the air cooler 15 is connected to the water-cooling separator 17 through a pipeline; the liquid outlet of the water-cooling separator 17 is connected to the water storage tank 16 through a pipeline; the carbon dioxide outlet of the water-cooling separator 17 is connected to the tube-side inlet of the liquefier 18 and the oxy-fuel combustion area through a pipeline; the tube-side outlet of the liquefier 18 is connected to the carbon dioxide storage tank 19 through a pipeline; the LNG cold energy air separation area is connected to the shell-side inlet of the liquefier 18 through a pipeline, and the shell-side outlet of the liquefier 18 is connected to the air heater 20 through a pipeline; the outlet of the air heater 20 is connected to the inlet of the expander 21 through a pipeline, and the outlet of the expander 21 is connected to the oxy-fuel combustion area through a pipeline; the output end of the expander 21 is connected to the generator 22, and the generator 22 is electrically connected to the electrolytic seawater oxygen production area.

[0032] It should be noted that the NG gas coming out of the LNG heat exchanger 12 enters the pre-cooler 14 and is heated to about 298K by the high-temperature flue gas coming out of the gas turbine 24 and then enters the gas turbine 24 for combustion. The high-temperature flue gas (a mixture of water and carbon dioxide) enters the air cooler 15 after passing through the pre-cooler 14, and the temperature is reduced to the ambient temperature, and then enters the water-cooling separator 17 to separate the water therein. The separated water enters the water storage tank 16 for storage. A part of the carbon dioxide gas coming out of the water separator 17 enters the mixer 23. A part passes through the liquefier 18 and is cooled and liquefied by the liquid oxygen from the liquid oxygen tank 5 and enters the carbon dioxide storage tank 19 for storage. The liquid oxygen enters the air heater 20 after passing through the liquefier 18 and heats the air to the normal temperature state. Then, the oxygen enters the expander 21 to do external work, and the output end of the expander 21 is connected to the generator 22. The oxygen coming out of the expander 21 enters the mixer 23 and is mixed with carbon dioxide.

[0033] The LNG cold energy air separation area includes an air filter 1, an air compressor 2, an air pre-cooler 3, a low-temperature heat exchanger 4, a liquid oxygen storage tank 5, a high-low pressure separation tower 6, a liquid nitrogen storage tank 7, an argon purifier 8, an argon purification tower 9, a liquid argon storage tank 10, a circulating nitrogen compressor 11, an LNG heat exchanger 12, and a nitrogen throttle valve 13;

[0034] The outlet of the air filter 1 is connected to the inlet of the air compressor 2 through a pipeline; the outlet of the air compressor 2 is connected to the inlet of the air pre-cooler 3 through a pipeline; the inlet of the air pre-cooler 3 is connected to the air inlet 1 (i) of the low-temperature heat exchanger 4 through a pipeline; the air outlet 1 (o) of the low-temperature heat exchanger 4 is connected to the air inlet of the high-low pressure separation tower 6 through a pipeline; the liquid oxygen outlet of the high-low pressure separation tower 6 is connected to the liquid oxygen storage tank 5 through a pipeline; the liquid nitrogen outlet of the high-low pressure separation tower 6 is connected to the liquid nitrogen storage tank 7 through a pipeline; the liquid argon-containing outlet of the high-low pressure separation tower 6 is connected to the inlet of the argon purifier 8 through a pipeline; the outlet of the argon purifier 8 is connected to the inlet of the argon purification tower 9 through a pipeline, and the argon purification tower 9 is connected to the liquid argon storage tank 10 through a pipeline;

[0035] The waste nitrogen outlet of the high-low pressure separation tower 6 is connected to the waste nitrogen inlet 2 (i) of the low-temperature heat exchanger 4 through a pipeline; LNG enters the LNG inlet 4 (i) of the LNG heat exchanger 12; the high-pressure circulating nitrogen secondary condensation outlet 3 (o) of the LNG heat exchanger 12 is connected to the inlet of the nitrogen throttle valve 13 through a pipeline; the outlet of the nitrogen throttle valve 13 is connected to the circulating liquid nitrogen inlet of the high-low pressure separation tower 6 through a pipeline; the circulating gas nitrogen outlet of the high-low pressure separation tower 6 is connected to the circulating nitrogen inlet 3 (i) of the low-temperature heat exchanger 4 through a pipeline; the circulating nitrogen outlet 3 (o) of the low-temperature heat exchanger 4 is connected to the circulating nitrogen inlet 1 (i) of the LNG heat exchanger 12 through a pipeline; the circulating nitrogen outlet 1 (o) of the LNG heat exchanger 12 is connected to the inlet of the circulating nitrogen compressor 11 through a pipeline; the outlet of the circulating nitrogen compressor 11 is connected to the circulating nitrogen primary condensation inlet 2 (i) of the LNG heat exchanger 12 through a pipeline; the circulating nitrogen primary condensation outlet 2 (o) of the LNG heat exchanger 12 is connected to the circulating nitrogen secondary condensation inlet 3 (i) of the LNG heat exchanger 12 through a pipeline;

[0036] The LNG outlet 4 (o) of the LNG heat exchanger 12 is connected to the tube-side inlet of the pre-cooler 14 through a pipeline; the outlet of the liquid oxygen storage tank 5 is connected to the shell-side inlet of the liquefier 18 through a pipeline.

[0037] It should be noted that in the LNG cold energy air separation area, air enters the air compressor 2 after passing through the air filter 1. The air is pressurized to 0.6 MPa and then enters the air pre-cooler 3 to be cooled to the ambient state;

[0038] After that, it enters the low-temperature heat exchanger 4 to reduce the temperature to 100K, and then enters the high-low pressure separation tower 6 to exchange heat with the circulating low-temperature liquid nitrogen therein. After the oxygen and nitrogen are liquefied and separated respectively, the oxygen enters the liquid oxygen storage tank 5 for storage, and the liquid nitrogen enters the liquid nitrogen storage tank 7 for storage;

[0039] The gas-liquid mixed state of liquid argon enters the argon purifier 8 and then enters the argon purification tower 9. The harmless waste gas separated by the argon purification tower 9 is discharged into the atmosphere, and the liquid argon enters the liquid argon storage tank 10;

[0040] The waste nitrogen coming out of the top of the high-low pressure separation tower 6 enters the low-temperature heat exchanger 4 to exchange heat with the air and then is discharged into the atmosphere. The 100 - 110K circulating nitrogen separated by the high-pressure separation tower 6 is heated to about 270K after exchanging heat with the air through the low-temperature heat exchanger 4 and then enters the LNG heat exchanger 12 where the temperature is reduced to 120K. Then, it passes through the circulating nitrogen compressor 11 to compress the nitrogen to a state of 195K and 2.6MPa and enters the LNG heat exchanger 12 again, and the temperature is reduced to 120K. After that, it passes through the nitrogen throttle valve 13, and the temperature and pressure are reduced to about 91K and 0.4MPa and then enters the high-low pressure separation tower 6.

[0041] The oxygen-rich combustion area includes a gas turbine 24 and a mixer 23, where: the outlet of the mixer 23 is connected to the gas inlet of the gas turbine 24 through a pipeline; the oxygen inlet of the mixer 23 is communicated with the outlet of the expander 21 through a pipeline, the carbon dioxide inlet of the mixer 23 is connected to the carbon dioxide outlet of the water-cooling separator 17 through a pipeline, and the fuel inlet of the gas turbine 24 is connected to the tube-side outlet of the pre-cooler 14 through a pipeline; the flue gas outlet of the gas turbine 24 is connected to the shell-side inlet of the pre-cooler 14 through a pipeline.

[0042] It should be noted that the high-oxygen-content gas coming out of the mixer 23 enters the gas turbine 24 and mixes with the NG gas for combustion.

[0043] The electrolytic seawater oxygen production area includes an electrolyzer 26, a hydrogen storage tank 25, and an oxygen storage tank 27. The generator 22 is electrically connected to the electrolyzer 26 to supply the electric energy generated by the generator 22 to the electrolyzer 26; the oxygen outlet of the electrolyzer 26 is connected to the oxygen storage tank 27 through a pipeline; the oxygen storage tank 27 is connected to the oxygen inlet of the mixer 23 through a pipeline; the hydrogen outlet of the electrolyzer 26 is connected to the hydrogen storage tank 25 through a pipeline.

[0044] It should be noted that seawater enters the electrolyzer 26, and the electrical input of the electrolyzer 26 comes from the generator 22. The oxygen generated by the electrolyzer 26 enters the oxygen storage tank 27 to ensure sufficient oxygen for oxygen-rich combustion. The hydrogen enters the hydrogen storage tank 25 for storage.

[0045] The above has shown and described the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments, and without departing from the spirit and scope of the present invention, the present invention will have various changes and improvements, and these changes and improvements all fall within the scope of the present invention claimed. The scope of protection claimed by the present invention is defined by the appended claims and their equivalents.

Claims

1. A novel oxy-fuel combustion carbon capture system for LNG ships, comprising a carbon dioxide collection area, characterized in that: It further includes an LNG cold energy air separation zone and an oxygen-enriched combustion zone, and the LNG cold energy air separation zone and the oxygen-enriched combustion zone are respectively connected to the carbon dioxide collection zone for realizing carbon capture on an LNG ship; The carbon dioxide collection zone includes a pre-cooler, an air cooler, a water storage tank, a water-cooled separator, a liquefier, a carbon dioxide storage tank, an air heater, an expander, and a generator; The tube side inlet of the pre-cooler is connected to the LNG cold energy air separation zone through a pipeline; the tube side outlet of the pre-cooler is connected to the oxygen-enriched combustion zone through a pipeline; the shell side outlet of the pre-cooler is connected to the air cooler through a pipeline; the outlet of the air cooler is connected to the water-cooled separator through a pipeline; the liquid outlet of the water-cooled separator is connected to the water storage tank through a pipeline; the carbon dioxide outlet of the water-cooled separator is connected to the tube side inlet of the liquefier and the oxygen-enriched combustion zone through a pipeline; the tube side outlet of the liquefier is connected to the carbon dioxide storage tank through a pipeline; the LNG cold energy air separation zone is connected to the shell side inlet of the liquefier through a pipeline, and the shell side outlet of the liquefier is connected to the air heater through a pipeline; the outlet of the air heater is connected to the inlet of the expander through a pipeline, and the outlet of the expander is connected to the oxygen-enriched combustion zone through a pipeline; the output end of the expander is connected to the generator, and the generator is electrically connected to the electrolytic seawater oxygen production zone; the LNG cold energy air separation zone includes an air filter, an air compressor, an air pre-cooler, a low-temperature heat exchanger, a liquid oxygen storage tank, a high-low pressure separation tower, a liquid nitrogen storage tank, an argon purifier, an argon purification tower, a liquid argon storage tank, a circulating nitrogen compressor, an LNG heat exchanger, and a nitrogen throttle valve; The outlet of the air filter is connected to the inlet of the air compressor through a pipeline; the outlet of the air compressor is connected to the inlet of the air pre-cooler through a pipeline; the outlet of the air pre-cooler is connected to the air inlet of the low-temperature heat exchanger through a pipeline; the air outlet of the low-temperature heat exchanger is connected to the air inlet of the high-low pressure separation tower through a pipeline; the liquid oxygen outlet of the high-low pressure separation tower is connected to the liquid oxygen storage tank through a pipeline; the liquid nitrogen outlet of the high-low pressure separation tower is connected to the liquid nitrogen storage tank through a pipeline; the liquid argon-containing outlet of the high-low pressure separation tower is connected to the inlet of the argon purifier through a pipeline; the outlet of the argon purifier is connected to the inlet of the argon purification tower through a pipeline, and the argon purification tower is connected to the liquid argon storage tank through a pipeline; The waste nitrogen gas outlet of the high-low pressure separation tower is connected to the waste nitrogen gas inlet of the low-temperature heat exchanger through a pipeline; LNG enters the LNG inlet of the LNG heat exchanger; the high-pressure circulating nitrogen secondary condensation outlet of the LNG heat exchanger is connected to the inlet of the nitrogen throttle valve through a pipeline; the outlet of the nitrogen throttle valve is connected to the circulating liquid nitrogen inlet of the high-low pressure separation tower through a pipeline; the circulating gas nitrogen outlet of the high-low pressure separation tower is connected to the circulating nitrogen inlet of the low-temperature heat exchanger through a pipeline; the circulating nitrogen outlet of the low-temperature heat exchanger is connected to the circulating nitrogen inlet of the LNG heat exchanger through a pipeline; the circulating nitrogen outlet of the LNG heat exchanger is connected to the inlet of the circulating nitrogen compressor through a pipeline; the outlet of the circulating nitrogen compressor is connected to the high-pressure circulating nitrogen primary condensation inlet of the LNG heat exchanger through a pipeline; the high-pressure circulating nitrogen primary condensation outlet of the LNG heat exchanger is connected to the high-pressure circulating nitrogen secondary condensation inlet of the LNG heat exchanger through a pipeline; The LNG outlet of the LNG heat exchanger is connected to the tube side inlet of the pre-cooler through a pipeline; the outlet of the liquid oxygen storage tank is connected to the shell side inlet of the liquefier through a pipeline; the oxygen-enriched combustion area includes a gas turbine and a mixer, wherein: the outlet of the mixer is connected to the gas inlet of the gas turbine through a pipeline; the oxygen inlet of the mixer is communicated with the outlet of the expander through a pipeline, the carbon dioxide inlet of the mixer is connected to the carbon dioxide outlet of the water-cooling separator through a pipeline, and the fuel inlet of the gas turbine is connected to the tube side outlet of the pre-cooler through a pipeline; the flue gas outlet of the gas turbine is connected to the shell side inlet of the pre-cooler through a pipeline.

2. The novel oxy-fuel combustion carbon capture system for LNG ships according to claim 1, characterized in that: It further includes an electrolytic seawater oxygen production area, one end of the electrolytic seawater oxygen production area is connected to the oxygen-enriched combustion area for supplying oxygen to the oxygen-enriched combustion area by the oxygen produced in the electrolytic seawater oxygen production area, and the carbon dioxide collection area is electrically connected to the electrolytic seawater oxygen production area for supplying power to the electrolytic seawater oxygen production area through the carbon dioxide collection area; the electrolytic seawater oxygen production area includes an electrolyzer, a hydrogen storage tank, and an oxygen storage tank, and the generator is electrically connected to the electrolyzer for supplying the electric energy generated by the generator to the electrolyzer; the oxygen outlet of the electrolyzer is connected to the oxygen storage tank through a pipeline end; the oxygen storage tank is connected to the oxygen inlet of the mixer through a pipeline; the hydrogen outlet of the electrolyzer is connected to the hydrogen storage tank through a pipeline.

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