A hydrogen storage and reliquefaction coupled fuel exhaust gas cryogenic capture system for liquid hydrogen-fuel dual-fuel ships

Abstract

The present invention provides a liquid hydrogen-fuel dual-fuel ship hydrogen storage reliquefaction coupled diesel exhaust low temperature capture system, including a low temperature helium and liquid hydrogen heat exchange network system, a helium refrigeration cycle system, and a ship main engine, a boiler tail gas low temperature capture system; the low temperature helium and liquid hydrogen heat exchange network system includes a liquid hydrogen storage tank, a liquid hydrogen pump I, a four-stream precooler, a two-stream supercooler, a three-stream heat exchanger, and a supercooled liquid hydrogen spraying positive-parahydrogen converter that are interconnected through pipelines in sequence; the helium refrigeration cycle system includes a liquid helium storage tank, a liquid helium pump, a regenerator, a helium compressor, and a helium expander; the ship main engine, The boiler tail gas low temperature capture system includes a liquid hydrogen pump II, a control valve, a back pressure valve, an exhaust precooler, an exhaust supercooler, a ship main engine, an auxiliary boiler, a fuel tank, an exhaust filter, and a CO2 enrichment storage. The present invention integrates hydrogen fuel reliquefaction storage and traditional fuel tail gas treatment, and is the development direction of future multi-energy complementary ships.

Description

Technical Field

[0001] The present invention relates to the fields of low-temperature fuel reliquefaction storage of new fuel ships, energy conservation and emission reduction of dual-fuel ships, and low-temperature CO2 capture of fuel exhaust gas. Specifically, it especially relates to a new energy ship multi-fuel composite system for hydrogen storage and reliquefaction of liquid hydrogen-fuel dual-fuel ships, a low-temperature helium compression and expansion refrigeration cycle, and the capture of exhaust gas CO2 using low-temperature cold energy. Background Art

[0002] At present, the storage of hydrogen mainly includes high-pressure gaseous hydrogen storage, low-temperature liquid hydrogen storage, metal hydride hydrogen storage and organic liquid hydrogen storage. Although for small vehicles such as cars, high-pressure gaseous hydrogen storage (mass density 4.0wt% volume density 39g / L) can already meet daily needs. However, for large ship power, it is necessary to use low-temperature liquid hydrogen storage with a mass hydrogen storage density of 5.7wt% and a volume hydrogen storage density of 70g / L, which is the largest hydrogen storage method known so far. However, liquid hydrogen, like liquid natural gas, is an extremely low-temperature fuel at around -252°C. It is generally used to be vaporized to room temperature before entering the engine, boiler or fuel cell. However, due to the huge temperature difference in the outside world, the tank leaks heat during the storage of liquid hydrogen storage tanks, and the problem of self-evaporation is inevitable. Therefore, how to reliquefy the hydrogen evaporated gas in the ship's liquid hydrogen tank and use the cold energy when the liquid hydrogen is vaporized is the key to the efficient use of hydrogen fuel.

[0003] There are some patents that mention the storage and utilization process system of liquid hydrogen. For example, the invention CN108561749A discloses a "mixed filling system for liquid hydrogen refueling stations", which explains that the mixed filling system for liquid hydrogen refueling stations has a liquid hydrogen filling unit and a high-pressure hydrogen filling unit, which provides more filling forms for hydrogen refueling stations. However, the process does not analyze in detail how to use liquid hydrogen gasification, or the reliquefaction process cannot provide a good solution for the lossless storage of hydrogen or liquid hydrogen, and cannot meet large-scale use and development on ships. Another example is the hydrogen reliquefaction device. The invention patent CN102155610B discloses a "cryogenic medium liquefaction device" that provides a method of integrating liquefying cryogenic media using a single or multiple refrigerators, which fully utilizes the heat transfer area of ​​the low-temperature end of the cold head of the refrigerator, reduces heat leakage, improves work efficiency and saves energy, and is easy to install and disassemble, and reduces manufacturing and maintenance costs. However, this invention requires a specific refrigerator for liquefaction, and the liquefaction temperature of hydrogen is extremely low, and the cold energy of gasification cannot be utilized, so it is difficult to scale up on ships. Invention CN111174529A discloses "a system and method for dehydrogenation and decarbonization using cold energy of liquefied natural gas". The system for dehydrogenation and decarbonization using cold energy of liquefied natural gas uses LNG cold energy to provide the cold energy required for liquefaction of each component in the dehydrogenation and decarbonization process. However, this technology can only improve the utilization efficiency of LNG cold energy by processing the mined natural gas or associated gas from oil fields using the cold energy released during the gasification process of liquefied natural gas. It cannot be integrated into the ship's power energy system, and cannot fully and comprehensively utilize the energy in the gasification and reliquefaction process of cryogenic liquids. Summary of the invention

[0004] According to the above existing hydrogen boil-off gas reliquefaction storage, liquid hydrogen regasification utilization, ship fuel exhaust gas treatment and related technologies cannot be used for energy joint utilization, resulting in a large amount of energy consumption and exhaust gas emissions, a liquid hydrogen-fuel dual-fuel ship hydrogen storage reliquefaction coupled diesel exhaust gas cryogenic capture system is proposed. The present invention takes low-temperature hydrogen boil-off gas reliquefaction as the starting point, and the ship low-temperature fuel cold energy utilization coupled with fuel exhaust gas cryogenic capture as a breakthrough, breaking the traditional method of only using low-temperature processes to cool liquefied materials, or collecting and treating the exhaust gas of ship main engine and auxiliary machine boilers. The present invention takes hydrogen storage and reliquefaction coupled with low-temperature capture of fuel exhaust gas as its main purpose. It utilizes a helium refrigeration cycle to supercool liquid hydrogen and reflux it back to the liquid hydrogen storage tank for a spray-type reliquefaction process, so that the low-temperature hydrogen vapor is reliquefied and converted into normal and para-hydrogen in the storage tank, and its conversion heat is taken away by another required hydrogen vapor to pre-cool the ship's main engine and auxiliary boiler combustion exhaust gas. The evaporative cold energy of the liquid hydrogen required by the fuel cell is used to condense the ship's exhaust gas to capture and liquefy CO2, and a series of energy conversion systems and methods are formed, forming a dual-fuel ship hydrogen vapor reliquefaction storage coupled with fuel exhaust gas capture energy-saving and emission reduction efficient utilization system.

[0005] The technical means adopted by the present invention are as follows:

[0006] A hydrogen storage and reliquefaction coupled diesel exhaust low temperature capture system for a liquid hydrogen-fuel dual fuel ship, including a low temperature helium and liquid hydrogen heat exchange network system, a helium refrigeration cycle system, and a ship main engine and boiler exhaust low temperature capture system;

[0007] The low-temperature helium and liquid hydrogen heat exchange network system comprises a liquid hydrogen storage tank, a liquid hydrogen pump I, a four-stream precooler, a two-stream supercooler, a three-stream heat exchanger, and a supercooled liquid hydrogen spraying normal-parahydrogen converter, which are interconnected through pipelines in sequence; liquid hydrogen is first pumped into the heat exchange network from the liquid hydrogen storage tank by the liquid hydrogen pump I, passes through the four-stream precooler, the two-stream supercooler, and the three-stream heat exchanger in sequence, and finally enters the supercooled liquid hydrogen spraying normal-parahydrogen converter located on the upper layer of the liquid hydrogen storage tank in the form of a supercooled liquid, and at the same time, the liquid hydrogen evaporation gas generated by the environmental heat leakage in the upper layer of the liquid hydrogen storage tank is reliquefied into liquid hydrogen, and the catalyst in the supercooled liquid hydrogen spraying normal-parahydrogen converter converts the high-temperature normal hydrogen into low-temperature and easy-to-store parahydrogen;

[0008] The helium refrigeration cycle system comprises a liquid helium storage tank, a liquid helium pump, a regenerator, a helium compressor and a helium expander; the liquid helium is first sent from the liquid helium storage tank into the three-stream heat exchanger and the two-stream supercooler in sequence by the liquid helium pump, flows through the regenerator and enters the helium compressor for compression, then flows through the four-stream precooler and the regenerator in sequence to release heat, and finally enters the expander to expand and do work to become low-temperature helium or liquid helium and then returns to the liquid helium storage tank;

[0009] The ship main engine and boiler exhaust low temperature capture system includes a liquid hydrogen pump II, a control valve, a back pressure valve, an exhaust precooler, an exhaust supercooler, a ship main engine, an auxiliary boiler, a fuel tank, an exhaust filter and a CO2 enrichment storage; the exhaust gas is the exhaust gas discharged after the fuel in the fuel tank in the dual-fuel powered ship is supplied to the auxiliary boiler and the ship main engine for combustion; the exhaust gas first passes through the exhaust filter to remove impurities, the impurities include nitrogen oxides, sulfur oxides and other impurities, and then enters the exhaust precooler and the exhaust supercooler in turn for heat exchange to liquefy CO2, and the liquefied CO2 is stored in the CO2 enrichment storage; the exhaust precooler and the exhaust supercooler are respectively connected to the liquid hydrogen storage tank, the control valve is arranged between the exhaust supercooler and the liquid hydrogen storage tank, and the back pressure valve is arranged between the exhaust precooler and the liquid hydrogen storage tank.

[0010] Furthermore, the working fluids circulating in the system include liquid helium, cryogenic helium, liquid hydrogen and supercooled liquid hydrogen; the energy transfer process in the system includes: the liquid helium first transfers the cold to the liquid hydrogen and supercooled liquid hydrogen in the two-stream supercooler and the three-stream heat exchanger, absorbs heat itself to become cryogenic helium, then passes through the regenerator to further increase the temperature and is compressed by the compressor, then enters the four-stream precooler and the regenerator in sequence to further reduce the heat and finally enters the expander for liquefaction or cooling.

[0011] Furthermore, the energy conversion process in the low-temperature capture system of the ship's main engine and boiler exhaust gas includes: first, the back pressure valve is used to control the flow rate of hydrogen evaporated gas from the liquid hydrogen storage tank into the exhaust gas precooler, and the exhaust gas is heat exchanged and precooled with the hydrogen evaporated gas in the exhaust gas precooler, and then the exhaust gas is passed into the exhaust gas supercooler, and the control valve is used to control the flow rate of liquid hydrogen from the liquid hydrogen storage tank into the supercooler, and the exhaust gas is heat exchanged with liquid hydrogen in the exhaust gas supercooler to condense and liquefy the CO2 in the exhaust gas.

[0012] Furthermore, the four-stream precooler, the two-stream supercooler, the three-stream heat exchanger, the regenerator, the exhaust gas precooler and the exhaust gas supercooler can be plate-fin type, plate type, printed type, coil type or shell and tube type heat exchangers, and the interior can be perforated, corrugated or serrated fins.

[0013] Furthermore, the liquid hydrogen storage tank and the supercooled liquid hydrogen spraying normal-parahydrogen converter are arranged in an integrated manner or in a separate manner.

[0014] Furthermore, the liquid CO2 in the CO2 enrichment storage tank can be used as a cold storage medium to supply ship air conditioning, food freezing and refrigeration, or transported to land for further processing as edible carbon dioxide.

[0015] Furthermore, the operation of the control valve and the back pressure valve is regulated according to the temperature, pressure and liquid level inside the system.

[0016] Compared with the prior art, the present invention has the following advantages:

[0017] 1. The hydrogen storage and reliquefaction coupled diesel exhaust gas cryogenic capture system for liquid hydrogen-fuel dual-fuel ships provided by the present invention can solve the energy utilization and conversion problems in the low-temperature fuel storage and evaporator reliquefaction process of new energy ships; it breaks the traditional technical model: it can adapt well to ship applications, cannot consider many parameters at the same time, and has relatively weak assessments of energy availability, environmental impact and cost; it abandons the current technical difficulties of separating the efficient utilization of renewable energy and new energy, and overcomes the reliquefaction of the liquid hydrogen storage tank after heat leakage during the storage process caused by the huge external temperature difference and the efficient utilization of the cold energy of liquid hydrogen gasification.

[0018] 3. The hydrogen storage and reliquefaction coupled diesel exhaust low-temperature capture system for liquid hydrogen-fuel dual-fuel ships provided by the present invention, and the fuel supply process of liquid hydrogen-fuel dual-fuel ships, firstly, when the ship is started, a hot start method mainly using fuel oil can be adopted, with auxiliary liquid hydrogen fuel supply. This flexible method can prevent low-temperature pipeline protection, and can also use the exhaust heat of auxiliary boilers and ship engines to gasify liquid hydrogen to reach the operating temperature of hydrogen fuel required by the engine; in addition, hydrogen fuel can not only be used for ordinary engine combustion, but also as the main fuel for fuel cells in electric-powered ships; specific navigation conditions and design forms such as fuel cells, combustion engines or hybrid power modes should be flexibly configured according to the power size, structural form and liquid hydrogen storage tank capacity of the ship.

[0019] 4. The liquid hydrogen-fuel dual-fuel ship hydrogen storage and reliquefaction coupled diesel exhaust low-temperature capture system provided by the present invention is economical, safe, environmentally friendly and energy-saving. Compared with the traditional method, the ship main engine and boiler exhaust low-temperature CO2 capture system is only started when fuel oil and hybrid power are used, thereby reducing exhaust emissions. In addition, the enriched liquid CO2 can be used as a cold storage medium such as dry ice to supply ship air conditioning, food freezing and refrigeration, or transported to land for further processing as edible carbon dioxide.

[0020] Based on the above reasons, the present invention can be widely promoted in the fields of ship multi-power systems and the like. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0022] Figure 1 This is a schematic diagram of the principle of the hydrogen storage and reliquefaction coupled fuel oil exhaust gas cryogenic capture system for a liquid hydrogen-fuel oil dual-fuel ship according to the present invention.

[0023] In the figure: 100, liquid hydrogen storage tank; 101, liquid hydrogen pump I; 102, four-stream precooler; 103, two-stream supercooler; 104, three-stream heat exchanger; 105, subcooled liquid hydrogen spray normal-parahydrogen converter; 201, liquid helium storage tank; 202, liquid helium pump; 203, regenerator; 204, helium compressor; 205, helium expander; 301, liquid hydrogen pump II; 302, control valve; 303, back pressure valve; 304, exhaust gas supercooler; 305, exhaust gas precooler; 306, auxiliary boiler; 307, ship main engine; 308, fuel tank; 309, exhaust gas filter; 310, CO2 enrichment storage. DETAILED DESCRIPTION

[0024] 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 only part of the embodiments of the present invention, not all of the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means intended to limit the present invention and its application or use. 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.

[0025] Example 1

[0026] like Figure 1 As shown, the present invention provides a hydrogen storage and reliquefaction coupled diesel exhaust low temperature capture system for liquid hydrogen-fuel dual fuel ships, including a low temperature helium and liquid hydrogen heat exchange network system, a helium refrigeration cycle system, and a ship main engine and boiler exhaust low temperature capture system;

[0027] The low-temperature helium and liquid hydrogen heat exchange network system comprises a liquid hydrogen storage tank 100, a liquid hydrogen pump I 101, a four-stream precooler 102, a two-stream supercooler 103, a three-stream heat exchanger 104 and a supercooled liquid hydrogen spraying normal-parahydrogen converter 105, which are interconnected in sequence through pipelines;

[0028] Liquid hydrogen is first pumped from the liquid hydrogen storage tank 100 into the heat exchange network by the liquid hydrogen pump I 101, passes through the four-stream precooler 102, the two-stream supercooler 103 and the three-stream heat exchanger 104 in sequence, and finally enters the supercooled liquid hydrogen spraying normal-parahydrogen converter 105 located on the upper layer of the liquid hydrogen storage tank 100 in the form of supercooled liquid, and at the same time, the liquid hydrogen evaporation gas generated by the environmental heat leakage in the upper layer of the liquid hydrogen storage tank 100 is reliquefied into liquid hydrogen, and the catalyst in the supercooled liquid hydrogen spraying normal-parahydrogen converter 105 converts the high-temperature normal hydrogen into low-temperature and easy-to-store parahydrogen;

[0029] The low-temperature helium and liquid hydrogen heat exchange network system for reliquefying hydrogen boil-off gas is a system for reliquefying hydrogen boil-off gas in a subcooled liquid hydrogen spraying normal-para hydrogen converter after low-temperature helium heats subcooled liquid hydrogen on the surface of the heat exchange network;

[0030] The helium refrigeration cycle system includes a liquid helium storage tank 201, a liquid helium pump 202, a regenerator 203, a helium compressor 204 and a helium expander 205;

[0031] Liquid helium is first sent from the liquid helium storage tank 201 to the three-stream heat exchanger 104 and the two-stream supercooler 103 in sequence by the liquid helium pump 202, flows through the regenerator 203 and enters the helium compressor 204 for compression, then flows through the four-stream precooler 102 and the regenerator 203 in sequence to release heat, and finally enters the expander 205 to expand and do work to become low-temperature helium or liquid helium and then returns to the liquid helium storage tank 201;

[0032] The helium refrigeration cycle system for continuously providing cold for liquid hydrogen storage is a system that provides cold for the low-temperature helium and liquid hydrogen heat exchange network system;

[0033] The ship main engine and boiler tail gas low temperature capture system includes a liquid hydrogen pump II 301, a control valve 302, a back pressure valve 303, a tail gas precooler 305, a tail gas supercooler 304, a ship main engine 307, an auxiliary boiler 306, a fuel tank 308, a tail gas filter 309 and a CO2 enrichment storage 310;

[0034] The tail gas is the exhaust gas discharged after the fuel in the fuel tank 308 in the dual-fuel powered ship is supplied to the auxiliary boiler 306 and the ship main engine 307 for combustion; the tail gas first passes through the tail gas filter 309 to remove impurities, the impurities include nitrogen oxides, sulfur oxides and other impurities, and then enters the tail gas precooler 305 and the tail gas supercooler 304 in sequence for heat exchange to liquefy CO2, and the liquefied CO2 is stored in the CO2 enrichment storage 310;

[0035] The tail gas precooler 305 and the tail gas supercooler 304 are respectively connected to the liquid hydrogen storage tank 100 , the control valve 302 is arranged between the tail gas supercooler 304 and the liquid hydrogen storage tank 100 , and the back pressure valve 303 is arranged between the tail gas precooler 305 and the liquid hydrogen storage tank 100 .

[0036] The low-temperature CO2 capture system used for purifying and capturing the tail gas of the main engine and boiler of a fuel-fired ship is a system that utilizes the low temperature to purify the tail gas and liquefy the CO2 emitted by the combustion of enriched fuel.

[0037] Furthermore, the working fluids circulating in the system include liquid helium, cryogenic helium, liquid hydrogen and supercooled liquid hydrogen; the energy transfer process in the system includes: the liquid helium first transfers the cold to the liquid hydrogen and supercooled liquid hydrogen in the two-stream supercooler 103 and the three-stream heat exchanger 104, absorbs heat itself to become cryogenic helium, then passes through the regenerator 203 to further increase the temperature and is compressed by the compressor 204, then enters the four-stream precooler 102 and the regenerator 203 in sequence to further reduce the heat and finally enters the expander 205 for liquefaction or cooling.

[0038] Furthermore, the energy conversion process in the ship main engine and boiler exhaust gas low-temperature capture system includes: first, the back pressure valve 303 is used to control the flow rate of hydrogen evaporated gas from the liquid hydrogen storage tank 100 into the exhaust gas precooler 305, and the exhaust gas is heat-exchanged and pre-cooled with the hydrogen evaporated gas in the exhaust gas precooler 305, and then the exhaust gas is passed into the exhaust gas supercooler 304, and the control valve 302 is used to control the flow rate of liquid hydrogen from the liquid hydrogen storage tank 100 into the supercooler 304, and the exhaust gas is heat-exchanged with liquid hydrogen in the exhaust gas supercooler 304 so that the CO2 in the exhaust gas is condensed and liquefied.

[0039] Furthermore, the working fluids in the ship main engine and boiler exhaust gas low temperature capture system include exhaust gas under different temperature conditions, liquid hydrogen, gaseous hydrogen, low temperature hydrogen vapor, etc.

[0040] Furthermore, the four-stream precooler 102, the two-stream supercooler 103, the three-stream heat exchanger 104, the regenerator 203, the exhaust gas precooler 305 and the exhaust gas supercooler 304 can be plate-fin type, plate type, printed type, coil type or shell and tube type heat exchangers. To increase heat exchange, the inside can be perforated, corrugated or serrated fins, and the convective heat transfer coefficient can also be increased by methods such as nano-electroplating surface treatment.

[0041] Furthermore, the liquid hydrogen storage tank 100 and the supercooled liquid hydrogen spraying normal-parahydrogen converter 105 are integrally arranged or separately arranged.

[0042] Due to heat leakage from the environment, some evaporated gas of liquid hydrogen will accumulate in the upper part of the liquid hydrogen storage tank, which will cause the pressure of the storage tank to gradually increase. In severe cases, rolling will occur. Therefore, it is necessary to condense and reliquefy a part of the hydrogen vapor in the upper part of the storage tank by circulating spraying of supercooled liquid hydrogen, so as to reduce the pressure in the storage tank and ensure the storage time and tank safety; the supercooled liquid hydrogen spraying normal-para-hydrogen converter 105 is equipped with low-temperature catalysts such as iron-based and nickel-based catalysts necessary for the conversion of normal-para-hydrogen, which are used to convert the liquefied normal-hydrogen into easily storable para-hydrogen, and the conversion heat is given to the remaining hydrogen vapor in the upper part of the storage tank. This part of the hydrogen vapor is transported to the tail gas precooler 305 by controlling the opening of the back pressure valve 303.

[0043] Furthermore, the ship's main engine and boiler exhaust low-temperature CO2 capture system is only started when using fuel oil and hybrid power to reduce exhaust emissions; the liquid CO2 in the CO2 enrichment storage tank 310 can be used as a cold storage medium such as dry ice to supply ship air conditioning, food freezing and refrigeration, or transported to land for further processing as edible carbon dioxide.

[0044] Furthermore, the system also includes multiple pipelines, valves and control module switches, not limited to the control valve 302 and the back pressure valve 303, which work to regulate according to the temperature, pressure and liquid level inside the system.

[0045] Furthermore, the fuel supply process of liquid hydrogen-fuel dual-fuel ships specifically includes: first, when the ship is started, a hot start method with fuel oil as the main method can be adopted, assisted by liquid hydrogen fuel supply. This flexible method can prevent low-temperature pipeline protection, and can also use the exhaust heat of auxiliary boilers and ship engines to gasify liquid hydrogen to reach the operating temperature of hydrogen fuel required by the engine; in addition, hydrogen fuel can not only be used for ordinary engine combustion, but also as the main fuel for fuel cells in electric-powered ships; specific navigation conditions and design forms such as fuel cells, combustion engines or hybrid power modes should be flexibly configured according to the ship's power size, structural form and liquid hydrogen storage tank capacity.

[0046] Furthermore, the liquid hydrogen-fuel dual-fuel ship hydrogen storage and reliquefaction coupled diesel exhaust gas cryogenic capture system described in the present invention is also applicable to other dual-fuel ship fuel storage and reliquefaction systems, including liquefied natural gas LNG-fuel dual power, liquid ammonia-fuel, combustible ice-fuel dual power, etc.

[0047] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A hydrogen storage and reliquefaction coupled diesel exhaust gas cryogenic capture system for a liquid hydrogen-fuel dual-fuel ship, characterized in that: Including low-temperature helium and liquid hydrogen heat exchange network system, helium refrigeration cycle system and ship main engine and boiler tail gas low-temperature capture system; The low-temperature helium and liquid hydrogen heat exchange network system comprises a liquid hydrogen storage tank (100), a liquid hydrogen pump I (101), a four-stream precooler (102), a two-stream supercooler (103), a three-stream heat exchanger (104), and a supercooled liquid hydrogen spraying normal-parahydrogen converter (105) which are interconnected in sequence through pipelines; liquid hydrogen is firstly pumped from the liquid hydrogen storage tank (100) into the heat exchange network by the liquid hydrogen pump I (101), and sequentially passes through the four-stream precooler (102). , the two-stream supercooler (103) and the three-stream heat exchanger (104), and finally enters the supercooled liquid hydrogen spraying normal-parahydrogen converter (105) located on the upper layer of the liquid hydrogen storage tank (100) in the form of supercooled liquid, and at the same time, the liquid hydrogen evaporation gas generated by the environmental heat leakage in the upper layer of the liquid hydrogen storage tank (100) is reliquefied into liquid hydrogen, and the catalyst in the supercooled liquid hydrogen spraying normal-parahydrogen converter (105) converts the high-temperature orthohydrogen into low-temperature and easy-to-store parahydrogen; The helium refrigeration cycle system comprises a liquid helium storage tank (201), a liquid helium pump (202), a regenerator (203), a helium compressor (204) and a helium expander (205); liquid helium is firstly sent from the liquid helium storage tank (201) into the three-stream heat exchanger (104) and the two-stream supercooler (103) in sequence by the liquid helium pump (202), flows through the regenerator (203) and enters the helium compressor (204) for compression, then flows through the four-stream precooler (102) and the regenerator (203) in sequence to release heat, and finally enters the expander (205) to expand and do work to become low-temperature helium or liquid helium and then returns to the liquid helium storage tank (201); The ship main engine and boiler tail gas cryogenic capture system comprises a liquid hydrogen pump II (301), a control valve (302), a back pressure valve (303), an tail gas precooler (305), an tail gas supercooler (304), a ship main engine (307), an auxiliary boiler (306), a fuel tank (308), an tail gas filter (309) and a CO2 enrichment storage (310); the tail gas is the waste gas discharged after the fuel in the fuel tank (308) of the dual-fuel powered ship is supplied to the auxiliary boiler (306) and the ship main engine (307) for combustion; the tail gas first passes through the tail gas filter (309) to remove impurities The impurities include nitrogen oxides, sulfur oxides and other impurities, and then enter the exhaust gas precooler (305) and the exhaust gas supercooler (304) in turn for heat exchange to liquefy CO2, and the liquefied CO2 is stored in the CO2 enrichment storage (310); the exhaust gas precooler (305) and the exhaust gas supercooler (304) are respectively connected to the liquid hydrogen storage tank (100), the control valve (302) is arranged between the exhaust gas supercooler (304) and the liquid hydrogen storage tank (100), and the back pressure valve (303) is arranged between the exhaust gas precooler (305) and the liquid hydrogen storage tank (100).

2. The hydrogen storage and reliquefaction coupled diesel exhaust gas cryogenic capture system for liquid hydrogen-fuel dual-fuel ships according to claim 1 is characterized in that: The working fluids circulating in the system include liquid helium, cryogenic helium, liquid hydrogen and supercooled liquid hydrogen; the energy transfer process in the system includes: the liquid helium first transfers cold energy to the liquid hydrogen and supercooled liquid hydrogen in the two-stream supercooler (103) and the three-stream heat exchanger (104), absorbs heat itself to become cryogenic helium, then passes through the regenerator (203) to further increase the temperature and is compressed by the compressor (204), then enters the four-stream precooler (102) and the regenerator (203) in sequence to further reduce the heat and finally enters the expander (205) for liquefaction or cooling.

3. The hydrogen storage and reliquefaction coupled diesel exhaust gas cryogenic capture system for liquid hydrogen-fuel dual-fuel ships according to claim 1 is characterized in that: The energy conversion process in the ship main engine and boiler exhaust gas low temperature capture system includes: first, the flow rate of hydrogen evaporated gas from the liquid hydrogen storage tank (100) into the exhaust gas precooler (305) is controlled by the back pressure valve (303), the exhaust gas is heat exchanged and precooled with the hydrogen evaporated gas in the exhaust gas precooler (305), and then the exhaust gas is passed into the exhaust gas supercooler (304), and the flow rate of liquid hydrogen from the liquid hydrogen storage tank (100) into the supercooler (304) is controlled by the control valve (302), and the exhaust gas is heat exchanged with liquid hydrogen in the exhaust gas supercooler (304) so ​​that CO2 in the exhaust gas is condensed and liquefied.

4. The hydrogen storage and reliquefaction coupled diesel exhaust gas cryogenic capture system for liquid hydrogen-fuel dual-fuel ships according to claim 1 is characterized in that: The liquid hydrogen storage tank (100) and the supercooled liquid hydrogen spraying normal-parahydrogen converter (105) are arranged in one piece or in separate pieces.

5. The hydrogen storage and reliquefaction coupled diesel exhaust gas cryogenic capture system for liquid hydrogen-fuel dual-fuel ships according to claim 1 is characterized in that: The liquid CO2 in the CO2 enrichment storage (310) can be used as a cold storage medium to supply ship air conditioning, food freezing and refrigeration, or transported to land for further processing as edible carbon dioxide.

6. The hydrogen storage and reliquefaction coupled diesel exhaust gas cryogenic capture system for liquid hydrogen-fuel dual-fuel ships according to claim 1 is characterized in that: The operation of the control valve (302) and the back pressure valve (303) is regulated according to the temperature, pressure and liquid level inside the system.

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