Carbon emission reduction system and method for LNG powered ships using SOFC

Abstract

The present application discloses an LNG-powered ship carbon emission reduction system and method using SOFC, wherein the carbon emission reduction system includes an LNG fuel supply system and a carbon recovery system. The LNG fuel supply system includes an LNG storage tank, a CO2 condenser, a natural gas heater, a ship gas-using device, and a flue gas emission device connected in sequence. The LNG storage tank stores LNG fuel. The ship gas-using device includes a ship engine and an SOFC fuel cell, and the cathode exhaust port of the SOFC fuel cell is connected to the flue gas emission device. The carbon recovery system includes a first cooler, a moisture removal device, and a CO2 liquefaction and storage device connected in sequence. The inlet of the first cooler is connected to the exhaust port of the post-combustion chamber of the SOFC fuel cell, and the gas outlet of the moisture removal device is connected to the CO2 liquefaction and storage device. The carbon emission reduction system and method provided by the present application can enable the ship to minimize the overall energy consumption while meeting the requirements of carbon emission reduction policies, with low operating costs, simple equipment structure, and small occupied space.

Description

Technical Field

[0001] The present invention relates to the technical field of carbon emission reduction for LNG powered ships, and in particular to a carbon emission reduction system for LNG powered ships using SOFC and a carbon emission reduction method for LNG powered ships using SOFC. Background Art

[0002] Under the influence of international emission control policies and carbon reduction trends, LNG power has become an important power option for ships, and global LNG-powered ships are entering a period of rapid development.

[0003] However, in addition to meeting the requirements for sulfur and nitrogen emissions, LNG can only partially meet the carbon emission requirements; and if some fuels that can fully meet the carbon emission requirements are used, such as methanol, ammonia, hydrogen and other fuels, they face a series of problems such as the difficulty in meeting the requirements with green fuel supply and excessively high costs.

[0004] At present, LNG itself has a certain carbon emission reduction capacity, but it has not yet reached the carbon emission reduction target expected to be achieved by the International Maritime Organization around 2030. Therefore, it has been questioned to a certain extent and is considered to be only a transitional fuel.

[0005] Therefore, how to make LNG-powered ships meet carbon emission requirements while reducing carbon emission reduction costs is one of the urgent issues that need to be solved. Summary of the invention

[0006] One advantage of the present invention is that it provides a carbon emission reduction system and method for LNG-powered ships using SOFC, wherein on the basis of the LNG fuel supply system, the characteristics of the SOFC fuel cell cathode reaction gas and the anode reaction gas being isolated from each other can be utilized to effectively exclude nitrogen that does not participate in the reaction, and concentrate on processing the generated carbon oxides, thereby greatly reducing the energy consumption of separating, collecting, and liquefying CO2. At the same time, the high efficiency of the SOFC fuel cell can further improve the system efficiency, and greatly reduce the operating costs while meeting the carbon emission reduction requirements.

[0007] One advantage of the present invention is that it provides a carbon emission reduction system and method for LNG-powered ships using SOFC, in which the cold energy contained in LNG fuel is used to collect and process the CO2 emitted after the SOFC fuel cell reaction, further saving energy consumption and reducing the overall operating cost of the system.

[0008] One advantage of the present invention is that it provides a carbon emission reduction system and method for LNG-powered ships using SOFC, wherein the carbon emission reduction system has a simple overall structure, occupies a small space, reduces unnecessary equipment investment, and has great development potential. It only requires that the power of the SOFC fuel cell installed on the ship reaches 25% to 30% of the ship engine power to meet the requirements of carbon emission reduction for ships in the near and medium term, making it easier for LNG-powered ships to achieve carbon emission reduction requirements, effectively making up for the shortcomings of LNG fuel in carbon emission issues, and having extremely high application value.

[0009] One advantage of the present invention is that it provides a carbon emission reduction system and method for LNG-powered ships using SOFC, which can not only fully utilize the waste heat and energy of the exhaust gas of the SOFC fuel cell, but also use the waste heat of the ship's engine to provide the required heat to the natural gas heater, and use seawater to cool the required gas, thereby minimizing fuel consumption as much as possible, improving the overall energy efficiency of the system, and reducing operating costs.

[0010] In order to achieve at least one of the above advantages of the present invention, in a first aspect, the present invention provides a carbon emission reduction system for an LNG powered ship using a SOFC, comprising:

[0011] An LNG fuel supply system, wherein the LNG fuel supply system comprises an LNG storage tank, a CO2 condenser, a natural gas heater, a ship gas equipment and a flue gas exhaust device connected in sequence, wherein the LNG storage tank stores LNG fuel, wherein the ship gas equipment comprises a ship engine and a SOFC fuel cell, and a cathode exhaust port of the SOFC fuel cell is connected to the flue gas exhaust device; and

[0012] A carbon recovery system, wherein the carbon recovery system comprises a first cooler, a moisture removal device and a CO2 liquefaction and storage device connected in sequence, wherein the inlet of the first cooler is connected to the exhaust port of the post-combustion chamber of the SOFC fuel cell, and the gas outlet of the moisture removal device is connected to the CO2 liquefaction and storage device.

[0013] According to one embodiment of the present invention, the SOFC fuel cell is further provided with an anode exhaust port for processing exhaust gas respectively relative to the cathode exhaust port, wherein the anode exhaust port is connected to the post-combustion chamber;

[0014] The SOFC fuel cell is also provided with an air inlet for introducing air, and the post-combustion chamber is provided with a pure oxygen supply interface for connecting to a pure oxygen supply device.

[0015] According to one embodiment of the present invention, the CO2 liquefaction and storage device comprises a compressor, a second cooler, the CO2 condenser and a liquid CO2 storage tank connected in sequence, wherein the outlet of the second cooler is connected to the gaseous CO2 inlet of the CO2 condenser, the liquid CO2 outlet of the CO2 condenser is connected to the liquid CO2 storage tank, and the CO2 condenser is further provided with an exhaust port on one side of the liquid CO2 outlet;

[0016] The second cooler is provided with a cooling medium inlet and a cooling medium outlet for heat exchange, so as to form a cooling medium circulation.

[0017] According to one embodiment of the present invention, the LNG storage tank is connected to the LNG inlet of the CO2 condenser through an LNG regulating valve, and is directly connected to the inlet of the natural gas heater after the CO2 condenser. The natural gas outlet of the CO2 condenser is connected to the inlet of the natural gas heater.

[0018] According to an embodiment of the present invention, the natural gas heater is provided with a heat exchange medium inlet and a heat exchange medium outlet for forming a heat cycle, wherein the heat source of the heat cycle is the waste heat generated by the ship's gas equipment.

[0019] According to one embodiment of the present invention, the first cooler comprises a waste heat utilization device and a seawater cooler, wherein the waste heat utilization device is located upstream of the seawater cooler to fully utilize the waste heat;

[0020] The seawater cooler is provided with a seawater inlet and a seawater outlet for heat exchange.

[0021] According to an embodiment of the present invention, the liquid CO2 storage tank is provided with a CO2 liquid outlet for transferring the liquid CO2 to other storage and transportation containers.

[0022] In a second aspect, the present invention further provides a method for reducing carbon emissions from an LNG powered ship using SOFC, comprising the following steps in sequence:

[0023] (a) Through heat exchange in the CO2 condenser and heating in the natural gas heater, the LNG fuel reaches the predetermined temperature required for use by the ship's gas equipment;

[0024] (b) The ship gas equipment includes a SOFC fuel cell, and the anode exhaust and cathode exhaust after the reaction of the SOFC fuel cell are processed separately, wherein the anode exhaust is directed to the afterburner of the SOFC fuel cell for oxygen-enriched combustion, and the final combustion products are CO2 and H2O, and the exhaust from the afterburner of the SOFC fuel cell is directed to the waste heat utilization equipment for waste heat utilization, wherein the cathode exhaust is discharged through the flue gas exhaust equipment;

[0025] (c) using seawater to further cool the temperature of the exhaust gas from the afterburner after waste heat utilization to seawater temperature;

[0026] (d) removing moisture from the exhaust gas by a moisture removal device;

[0027] (e) compressing the exhaust gas after removing moisture;

[0028] (f) cooling the compressed exhaust gas;

[0029] (g) passing the compressed and cooled exhaust gas into the CO2 condenser, and adjusting the flow rate of the LNG fuel entering the CO2 condenser in step (a) by an LNG regulating valve to maintain the temperature of the liquid CO2 flowing out of the liquid CO2 outlet of the CO2 condenser at a set desired temperature;

[0030] (h) transporting the condensed liquid CO2 to a liquid CO2 storage tank for storage, and transferring the liquid CO2 stored in the liquid CO2 storage tank to a container outside the ship when necessary, so as to achieve the purpose of reducing carbon emissions from the ship.

[0031] According to an embodiment of the present invention, in step (e), the pressure range of the compressed gas is 0.6 MPa to 1 MPa.

[0032] According to an embodiment of the present invention, in step (g), under the regulation of the LNG regulating valve, the temperature range of the liquid CO2 flowing out of the CO2 condenser is -65°C to -55°C.

[0033] These and other objects, features and advantages of the present invention will be fully reflected in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 A schematic diagram showing the principles of a carbon emission reduction system and method for an LNG powered ship using SOFC according to a preferred embodiment of the present application. DETAILED DESCRIPTION

[0035] The following description is used to disclose the present invention so that those skilled in the art can implement the present invention. The preferred embodiments described below are only examples, and those skilled in the art can think of other obvious variations. The basic principles of the present invention defined in the following description can be applied to other embodiments, variations, improvements, equivalents, and other technical solutions that do not deviate from the spirit and scope of the present invention.

[0036] Those skilled in the art should understand that, in the disclosure of the specification, the orientation or position relationship indicated by the terms "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc. are based on the orientation or position relationship shown in the drawings, which are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation. Therefore, the above terms should not be understood as limiting the present invention.

[0037] It is to be understood that the term "one" should be understood as "at least one" or "one or more", that is, in one embodiment, the number of an element may be one, while in another embodiment, the number of the element may be multiple, and the term "one" should not be understood as a limitation on the quantity.

[0038] refer to Figure 1 According to a preferred embodiment of the present invention, a carbon emission reduction system for LNG powered ships using SOFC will be described in detail below. SOFC, solid oxide fuel cell, belongs to the third generation fuel cell. It is an all-solid-state chemical power generation device that directly converts chemical energy stored in fuel and oxidant into electrical energy in an efficient and environmentally friendly manner at medium and high temperatures. It is one of the fuel cells with the highest theoretical energy density. SOFC fuel cells have the characteristics of separable anode and cathode reaction gases, wherein the anode exhaust gas leads to the afterburner chamber of the SOFC fuel cell. Only pure oxygen needs to be introduced into the afterburner chamber to achieve complete combustion of the afterburner chamber, so that the exhaust gas in the afterburner chamber contains only CO2 and H2O, wherein the main components of the cathode exhaust gas are nitrogen and unreacted oxygen and other components in the air, which can be connected to the flue gas emission equipment (such as chimney) for emission, with high temperature and high-quality waste heat, and can be used for waste heat utilization, such as recovering the heat energy therein through waste heat boilers and heat exchange devices.

[0039] Specifically, the carbon emission reduction system for LNG-powered ships using SOFC includes an LNG fuel supply system and a carbon recovery system, wherein the LNG fuel supply system includes an LNG storage tank 100, a CO2 condenser 12, a natural gas heater 13, a ship gas equipment and a flue gas emission equipment 16 connected in sequence, wherein the LNG storage tank 100 stores LNG fuel, and the ship gas equipment includes a ship engine 14 and a SOFC fuel cell 15. At the same time, the cathode exhaust port of the SOFC fuel cell 15 is connected to the flue gas emission equipment 16, such as a chimney, for discharging the cathode exhaust, i.e., nitrogen and unreacted oxygen and other components in the air. This part of the discharged gas has a higher temperature and can also be used as high-quality waste heat to fully recover the heat energy therein before discharge. , for other purposes; the carbon recovery system includes a first cooler, a moisture removal device 23 and a CO2 liquefaction and storage device connected in sequence, wherein the inlet of the first cooler is connected to the exhaust port P2 of the after-combustion chamber of the SOFC fuel cell 15, for receiving the exhaust of the after-combustion chamber, that is, the exhaust containing only CO2 and H2O, wherein the gas outlet of the moisture removal device 23 is connected to the CO2 liquefaction and storage device, and the gas after the moisture is removed is mostly CO2, and the concentration of CO2 is above 95%, and can even be as high as 99%, wherein the removed moisture is discharged through the moisture outlet 231 at the bottom of the moisture removal device 23, and the gas after the moisture is removed, that is, the high-concentration CO2 gas, is liquefied by the CO2 liquefaction and storage device, and then stored.

[0040] Therefore, on the basis of the ship's LNG fuel supply system, the characteristics of the separation of the anode and cathode reaction gases of the SOFC fuel cell 15 can be utilized to effectively reduce the energy consumption of processing, liquefying and collecting CO2. The overall structure of the system is simple and easy to be put into use quickly and for large-scale and wide-range applications. At the same time, it can also effectively improve the overall energy efficiency of the system while meeting the requirements of carbon emission reduction.

[0041] When natural gas is burned in the ship engine, the ship engine 14 inhales enough air through the air inlet 141 to ensure that the natural gas can be burned with oxygen. The flue gas generated by the combustion is discharged through the flue gas discharge device 16 (such as a chimney). The discharged flue gas is not further separated, collected and processed by CO2 in this application. Of course, processing equipment can be added, but additional equipment and ship space will be occupied, which is not considered in this application. The discharged flue gas can also be further recovered through the waste heat boiler to improve the overall energy utilization efficiency of the system.

[0042] In one embodiment, the SOFC fuel cell 15 is provided with an air inlet 151 for introducing air, and the air inlet 151 provides sufficient air to the SOFC fuel cell 15. Due to the unique internal structure of the SOFC fuel cell 15, the fuel and the air are not mixed during the electrochemical reaction, which provides favorable conditions for the subsequent treatment of CO2.

[0043] The SOFC fuel cell 15 also has an anode exhaust port that is separately arranged from the cathode exhaust port, wherein the anode exhaust port is connected to the after-combustion chamber. At the same time, the after-combustion chamber is provided with a pure oxygen supply interface 152 for connecting to a pure oxygen supply device, which is used to introduce pure oxygen into the after-combustion chamber to achieve complete combustion in the after-combustion chamber, ensuring that the exhaust gas from the after-combustion chamber contains only CO2 and H2O, thereby facilitating the liquefaction and collection of CO2.

[0044] Further preferably, the CO2 liquefaction and storage device includes a compressor 24, a second cooler 25, the CO2 condenser 12 and a liquid CO2 storage tank 200 connected in sequence, wherein the second cooler 25 is provided with a cooling medium inlet 251 and a cooling medium outlet 252 for heat exchange, for forming a cooling medium circulation, wherein the cooling medium can be preferably selected as seawater, which is convenient to obtain and sufficient, wherein the outlet of the second cooler 25 is connected to the gaseous CO2 inlet 123 of the CO2 condenser 12, and at the same time, the liquid CO2 outlet 124 of the CO2 condenser 12 is connected to the liquid CO2 storage tank 200, so that the cold energy contained in the LNG fuel is fully utilized to condense and process CO2 in the CO2 condenser 12, so as to achieve the purpose of greatly reducing the large amount of energy required in the process of collecting liquefied CO2; in addition, the CO2 condenser 12 is also provided with an exhaust port 125 on one side of the liquid CO2 outlet for discharging uncondensed gas.

[0045] Theoretical calculation and analysis show that if the power of the SOFC fuel cell configured on the ship is 25% to 30% of the ship's engine power, all the CO2 emitted by the SOFC fuel cell 15 can be collected and processed. Even if the exhaust gas from the ship's engine 14 is not separated and collected at all, the overall carbon emission reduction effect of the ship can achieve a 40% reduction compared with conventional fuel oil, which can basically meet the short- and medium-term carbon emission reduction targets.

[0046] As a preferred embodiment, the LNG storage tank 100 is connected to the LNG inlet 121 of the CO2 condenser 12 through the LNG regulating valve 11, and is directly connected to the inlet of the natural gas heater 13 through the other way. At the same time, the natural gas outlet 122 of the CO2 condenser 12 is connected to the inlet of the natural gas heater 13, so that the flow rate of the LNG fuel directly entering the CO2 condenser 12 can be adjusted by the LNG regulating valve 11 to ensure that the temperature of the liquid CO2 flowing out of the liquid CO2 outlet 124 of the CO2 condenser 12 is within the set temperature range.

[0047] In summary, the CO2 condenser 12 is simultaneously used in the LNG fuel supply system and the carbon recovery system, wherein in the LNG fuel supply system, the CO2 condenser 12 has a relative LNG inlet 121 and a natural gas outlet 122, that is, the temperature of the LNG fuel in the LNG storage tank 100 at the discharge port P1 is about -162°C, and the LNG fuel first enters the CO2 condenser 12 through the LNG inlet 121, and then flows out to the inlet of the natural gas heater 13 through the natural gas outlet 122, wherein in the carbon recovery system, the CO2 condenser 12 has a relative gaseous CO2 inlet 123 and a liquid CO2 outlet 124, that is, the gaseous CO2 in the carbon recovery system enters the CO2 condenser 12 from the gaseous CO2 inlet 123, and then flows out from the liquid CO2 outlet 124, thereby, the CO2 condenser 12 can fully utilize the huge cold energy contained in the LNG fuel to condense the CO2 gas into liquid CO2.

[0048] It should be emphasized that in order to accurately control the condensation temperature of CO2 in the carbon recovery system so that CO2 can be condensed and liquefied but not frozen into dry ice due to too low a temperature, so as to facilitate the storage of liquid CO2, the LNG storage tank 100 is connected to the LNG inlet 121 of the CO2 condenser 12 through the LNG regulating valve 11, and is directly connected to the inlet of the natural gas heater 13 through the other way. In this way, the LNG fuel flow to the LNG inlet 121 can be adjusted by the LNG regulating valve 11, so as to control the condensation temperature of the liquefied CO2, for example, the temperature of the liquid CO2 flowing out of the liquid CO2 outlet 124 in the carbon recovery system is maintained at -65°C to -55°C, preferably -60°C. In addition, it should be noted that after adjustment by the LNG regulating valve 11, the LNG fuel that does not flow into the CO2 condenser 12 will flow directly to the natural gas heater 13 for heating, so as to ensure that the gas consumption of the ship's gas equipment is not affected.

[0049] Preferably, the natural gas heater 13 is provided with a heat exchange medium inlet 131 and a heat exchange medium outlet 132 for forming a heat cycle, wherein the heat source of the heat cycle is the waste heat generated by the ship's gas equipment, so as to make full use of the waste heat generated by the ship to further improve energy efficiency.

[0050] Further preferably, the first cooler includes a waste heat utilization device 21 and a seawater cooler 22, wherein the waste heat utilization device 21 is located upstream of the seawater cooler 22. Since the temperature of the exhaust gas from the after-combustion chamber is relatively high and is a high-quality heat source, it can be fully utilized by the waste heat utilization device 21 to achieve the effect of reducing the exhaust temperature of the after-combustion chamber. The seawater cooler 22 is provided with a seawater inlet 221 and a seawater outlet 222 for heat exchange. By cooling with seawater, the temperature of the exhaust gas from the after-combustion chamber can be reduced to the seawater temperature, moisture can be precipitated, and subsequent processing is facilitated.

[0051] Further preferably, the liquid CO2 storage tank 200 is provided with a CO2 liquid outlet 201. The liquid CO2 storage tank 200 has the ability to insulate and keep cold, and can store liquid CO2 for a long time. During the voyage, the ship continuously generates new liquid CO2. These liquid CO2 can be first stored in the liquid CO2 storage tank 200, and after reaching a certain capacity or when necessary, they can be transferred to the shore-based liquid CO2 storage tank through the CO2 liquid outlet 201, or transferred to a dedicated liquid CO2 transport ship, and finally discharged into the CO2 storage depot transformed from waste gas oil and gas wells at the bottom of the ocean, so as to achieve the ultimate goal of reducing CO2 emissions.

[0052] In a second aspect, based on the same working principle, the present invention also provides a method for reducing carbon emissions of an LNG powered ship using SOFC, comprising the following steps:

[0053] (a) The LNG fuel reaches a predetermined temperature required for use by ship gas equipment through heat exchange in the CO2 condenser 12 and heating in the natural gas heater 13;

[0054] (b) The ship gas equipment includes a ship engine 14 and a SOFC fuel cell 15, wherein the anode exhaust and cathode exhaust after the reaction of the SOFC fuel cell 15 are processed separately, wherein the anode exhaust is directed to the afterburner chamber of the SOFC fuel cell 15, where pure oxygen is introduced for oxygen-enriched combustion, and the final combustion products are CO2 and H2O, and then the exhaust from the afterburner chamber of the SOFC fuel cell 15 is directed to the waste heat utilization device 21 for waste heat utilization and to reduce the temperature of the exhaust gas, wherein the cathode exhaust is discharged through the flue gas exhaust device 16, and may also be discharged after the waste heat in the cathode exhaust is recovered;

[0055] (c) using seawater to further cool the temperature of the exhaust gas from the afterburner after waste heat utilization to seawater temperature;

[0056] (d) removing moisture from the exhaust gas by a moisture removal device 23;

[0057] (e) compressing the exhaust gas after dehydration by means of a compressor 24;

[0058] (f) cooling the compressed exhaust gas;

[0059] (g) passing the compressed and cooled exhaust gas into the CO2 condenser 12, and adjusting the flow rate of the LNG fuel entering the CO2 condenser 12 in step (a) by the LNG regulating valve 11, so as to maintain the temperature of the liquid CO2 flowing out of the liquid CO2 outlet 124 of the CO2 condenser 12 at the set desired temperature;

[0060] (h) Conveying the condensed liquid CO2 to the liquid CO2 storage tank 200 for storage, and transferring the liquid CO2 stored in the liquid CO2 storage tank 200 to a container outside the ship when necessary, so as to achieve the purpose of reducing carbon emissions from the ship.

[0061] Further preferably, in step (e), the pressure range of the compressed gas is about 1 MPa, preferably 0.6 MPa to 1 MPa, wherein 0.6 MPa to 1 MPa is a relatively low working pressure, which can significantly reduce the energy consumed in gas compression.

[0062] Further preferably, in step (g), under the regulating action of the LNG regulating valve, the temperature range of the liquid CO2 flowing out of the CO2 condenser is -65°C to -55°C, such as -60°C, thereby making full use of the cold energy contained in the LNG fuel to condense most of the CO2 into liquid, thereby reducing the large amount of energy required in the CO2 liquefaction process.

[0063] In addition, the timing for transferring the liquid CO2 stored in the liquid CO2 storage tank 200 to a container other than a ship may be after the liquid CO2 storage tank 200 reaches its volume limit, or when there are more convenient liquid CO2 transport ship resources. At this time, the liquid CO2 can be transferred to other shore-based storage containers or liquid CO2 transport ships, and then transported and finally discharged into a CO2 storage reservoir converted from waste gas wells at the bottom of the ocean, thereby achieving the ultimate goal of reducing carbon emissions from ships.

[0064] It should be noted that the terms "first, second and third" in the present invention are only used for descriptive purposes and do not indicate any order. They cannot be understood as indicating or implying relative importance. These terms can be interpreted as names.

[0065] It should be understood by those skilled in the art that the embodiments of the present invention described above and shown in the accompanying drawings are only examples and do not limit the present invention. The advantages of the present invention have been fully and effectively achieved. The functional and structural principles of the present invention have been demonstrated and explained in the embodiments, and the embodiments of the present invention may be deformed or modified in any way without departing from the principles.

Claims

1. A method for reducing carbon emissions from an LNG-powered ship using SOFC, and a system for reducing carbon emissions from an LNG-powered ship using SOFC, wherein the system comprises an LNG fuel supply system and a carbon recovery system, wherein the LNG fuel supply system comprises an LNG storage tank, a CO2 condenser, a natural gas heater, ship gas equipment and flue gas emission equipment connected in sequence, wherein the LNG storage tank stores LNG fuel, wherein the ship gas equipment comprises a ship engine and a SOFC fuel cell, and the cathode exhaust port of the SOFC fuel cell is connected to the flue gas emission equipment; wherein the carbon recovery system comprises a first cooler, a moisture removal device and a CO2 liquefaction and storage device connected in sequence, wherein the inlet of the first cooler is connected to the exhaust port of the after-combustion chamber of the SOFC fuel cell, and the gas outlet of the moisture removal device is connected to the CO2 liquefaction and storage device, characterized in that, The method for reducing carbon emissions of LNG powered ships using SOFC comprises the following steps in sequence: (a) Through the heat exchange of the CO2 condenser and the heating of the natural gas heater, the LNG fuel reaches the predetermined temperature required for the use of the ship's gas equipment; (b) The ship gas equipment includes a SOFC fuel cell, and the anode exhaust and cathode exhaust after the reaction of the SOFC fuel cell are processed separately, wherein the anode exhaust is directed to the afterburner of the SOFC fuel cell for oxygen-enriched combustion, and the final combustion products are CO2 and H2O, and the exhaust of the afterburner of the SOFC fuel cell is directed to the waste heat utilization equipment for waste heat utilization, wherein the cathode exhaust is discharged through the flue gas emission equipment; (c) using seawater to further cool the exhaust temperature of the afterburner after waste heat utilization to seawater temperature; (d) removing moisture from the exhaust gas by a moisture removal device; (e) compressing the exhaust gas after removing moisture; (f) cooling the compressed exhaust gas; (g) passing the compressed and cooled exhaust gas into the CO2 condenser, and adjusting the flow rate of the LNG fuel entering the CO2 condenser in step (a) by an LNG regulating valve to maintain the temperature of the liquid CO2 flowing out of the liquid CO2 outlet of the CO2 condenser at a set desired temperature; (h) transporting the condensed liquid CO2 to a liquid CO2 storage tank for storage, and transferring the liquid CO2 stored in the liquid CO2 storage tank to a container outside the ship when necessary, so as to achieve the purpose of reducing carbon emissions from the ship.

2. The carbon emission reduction method for LNG powered ships using SOFC as claimed in claim 1, characterized in that: In step (e), the pressure range of the compressed gas is 0.6 MPa to 1 MPa.

3. The carbon emission reduction method for LNG powered ships using SOFC as claimed in claim 2, characterized in that: In step (g), under the regulation of the LNG regulating valve, the temperature range of the liquid CO2 flowing out of the CO2 condenser is -65°C to -55°C.

4. The carbon emission reduction method for LNG powered ships using SOFC as claimed in claim 1, characterized in that: The SOFC fuel cell is also provided with an anode exhaust port for processing exhaust gas respectively relative to the cathode exhaust port, wherein the anode exhaust port is connected to the post-combustion chamber; The SOFC fuel cell is also provided with an air inlet for introducing air, and the post-combustion chamber is provided with a pure oxygen supply interface for connecting to a pure oxygen supply device.

5. The carbon emission reduction method for LNG powered ships using SOFC as claimed in claim 4, characterized in that: The CO2 liquefaction and storage device comprises a compressor, a second cooler, the CO2 condenser and a liquid CO2 storage tank which are connected in sequence, wherein the outlet of the second cooler is connected to the gaseous CO2 inlet of the CO2 condenser, the liquid CO2 outlet of the CO2 condenser is connected to the liquid CO2 storage tank, and the CO2 condenser is further provided with an exhaust port on one side of the liquid CO2 outlet; The second cooler is provided with a cooling medium inlet and a cooling medium outlet for heat exchange, so as to form a cooling medium circulation.

6. The carbon emission reduction method for LNG powered ships using SOFC as claimed in claim 5, characterized in that: The LNG storage tank is connected to the LNG inlet of the CO2 condenser through an LNG regulating valve, and is directly connected to the inlet of the natural gas heater after the CO2 condenser. The natural gas outlet of the CO2 condenser is connected to the inlet of the natural gas heater.

7. The method for reducing carbon emissions from LNG powered ships using SOFC as claimed in claim 6, characterized in that: The natural gas heater is provided with a heat exchange medium inlet and a heat exchange medium outlet for forming a heat cycle, wherein the heat source of the heat cycle is the waste heat generated by the ship gas equipment.

8. The method for reducing carbon emissions from LNG powered ships using SOFC as claimed in claim 7, characterized in that: The first cooler comprises a waste heat utilization device and a seawater cooler, wherein the waste heat utilization device is located upstream of the seawater cooler to fully utilize the waste heat; The seawater cooler is provided with a seawater inlet and a seawater outlet for heat exchange.

9. The method for reducing carbon emissions from an LNG powered ship using SOFC as claimed in claim 8, characterized in that: The liquid CO2 storage tank is provided with a CO2 liquid outlet for transferring the liquid CO2 to other storage and transportation containers.

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