System for preparing and treating excess evaporated gas by adopting methanol for liquid hydrogen ship

Abstract

The invention belongs to the technical field of ships, and provides a system for processing excess boil-off gas by methanol preparation for a liquid hydrogen ship, which comprises a hydrogen fuel supply system, a methanol preparation system, a methanol supply system and a CO2 cold insulation system. According to the invention, excessive BOG of the liquid hydrogen ship reacts with CO2 to prepare methanol and store the methanol during stormy days or maneuvering sailing, and when the amount of BOG cannot meet the requirement of a main engine in the normal sailing process of the ship, the methanol is used as fuel for the ship, so that the cost of equipping a BOG reliquefaction device for the ship is saved, and the problem of excessive BOG of the liquid hydrogen ship is effectively solved; and meanwhile, part of CO2 is loaded on the liquid hydrogen ship, cold insulation is conducted on the CO2 in the C-shaped tank through cold energy generated by the liquid hydrogen supply main machine, BOG of the CO2 is reduced, the liquid hydrogen cold energy is reasonably utilized, and good innovativeness is achieved.

Description

Technical Field

[0001] This invention belongs to the field of marine technology, specifically relating to a system for treating excess vapor gas in a liquid hydrogen ship using methanol. Background Technology

[0002] As the energy structure shifts towards cleaner and lower-carbon energy, global demand for clean fuels is increasing, leading to a rise in the number of liquid hydrogen transport ships. To maximize hydrogen transport capacity, hydrogen is typically stored in liquid form in cargo holds. Liquid hydrogen is usually stored at around -253°C, creating a significant temperature difference with the outside atmosphere. Therefore, even with good insulation, liquid hydrogen vapor (BOG) is inevitably produced. Since BOG is composed of hydrogen, a high-calorific-value, pollution-free clean energy source, liquid hydrogen ships typically burn the produced BOG during voyages.

[0003] During the voyage of a liquid hydrogen ship, when the weather is good (sea conditions are favorable), the ship's speed (approximately 19 knots) is relatively high. At this time, the ship's main engine (dual-fuel engine) has high power (the power of the main engine is proportional to the cube of the speed), and the generated liquid hydrogen gas (BOG) can be completely burned by the main engine. When the BOG production cannot meet the main engine's demand, some liquid hydrogen needs to be vaporized to obtain sufficient BOG for combustion. When the ship encounters rough seas or maneuvering, the speed is greatly reduced, and the amount of BOG burned by the main engine is significantly decreased. Furthermore, due to the low density of liquid hydrogen, the liquid hydrogen ship has a shallow draft when fully loaded. In rough seas, the ship rolls violently, and the mechanical energy generated by the liquid hydrogen in the tanks during this rolling is partially converted into heat energy, further increasing BOG production. Based on these two reasons, the ship will experience BOG excess (i.e., the evaporated liquid hydrogen cannot be completely burned by the main engine) during rough seas or maneuvering.

[0004] The above describes the handling of BOG (Boiled Air Gathering) generated during the voyage of a liquid hydrogen ship. The method for handling excess BOG is to liquefy it using a reliquefaction unit and store it in the liquid hydrogen tank. However, due to the extremely low storage temperature of liquid hydrogen, the requirements for the liquefaction unit are very high, and the equipment and operating costs of the unit are also very high, resulting in a very high cost for BOG reliquefaction. Because this method has obvious drawbacks, the proper handling of excess BOG is a key technical challenge that liquid hydrogen ships need to solve.

[0005] Currently, the technology for producing methanol using CO2 and hydrogen is very mature. The production process is simple and the cost is relatively low. The produced methanol is a clean fuel, and it is liquid at room temperature and pressure, making it convenient to store and transport. It is an ideal clean fuel for ships.

[0006] Due to increased global carbon emission requirements, ships and factories are required to equip themselves with carbon capture devices to capture CO2 emissions, which are then transported to ports for centralized unloading. This has led to an ever-increasing amount of CO2 storage, which ports cannot utilize. As a result, ports will have a large amount of "CO2 waste" in the future, which will need to be transported by CO2 transport ships to designated locations for deep-sea storage. Moreover, the cost of storage is very high. Therefore, it will be very easy to obtain CO2 from ports in the future.

[0007] Based on the above problems, this invention proposes a system for treating excess BOG (Bolognese Bolognese Gas) on liquid hydrogen ships by producing methanol. In windy or turbulent weather or during maneuvering, excess BOG is reacted with CO2 to produce methanol, which is then stored in the cargo hold. When the ship's speed is high and the amount of BOG cannot meet the main engine's requirements, methanol is used as fuel for the ship. This system effectively solves the problem of excess BOG during liquid hydrogen ship navigation and has significant innovation and practical value. Summary of the Invention

[0008] The purpose of this invention is to address the problem of handling excess vapors from liquid hydrogen ships by proposing a system for treating excess vapors from liquid hydrogen ships using methanol production. This system includes a hydrogen fuel supply system, a methanol production system, a methanol supply system, and a CO2 cooling system.

[0009] The hydrogen fuel supply system includes: a liquid hydrogen tank, a compressor, a liquid hydrogen pump, a heat exchanger, a heating unit I, a fuel valve group I, a hydrogen fuel engine, a hydrogen generator, a shipboard electrical grid, and a propulsion motor.

[0010] The methanol production system includes: a liquid hydrogen chamber, a compressor, a BOG valve, a methanol production unit, a C-type tank, a CO2 pump, and a methanol chamber.

[0011] The methanol supply system includes: a methanol tank, a methanol pump, a heating unit II, a fuel valve group II, a methanol fuel engine, a methanol generator, a ship's electrical grid, and a propulsion motor.

[0012] The CO2 insulation system includes: a liquid hydrogen chamber, a compressor, a heat exchanger, a circulating pump, and a C-type tank.

[0013] In the hydrogen fuel supply system, the liquid hydrogen pump is placed at the bottom of the liquid hydrogen tank and connected to Heating Unit I via a pipeline; simultaneously, the liquid hydrogen tank is connected in sequence to the compressor, heat exchanger, and Heating Unit I via another pipeline; Heating Unit I is connected in sequence to Fuel Valve Group I and the hydrogen fuel engine via pipelines, and the function of Heating Unit I is to heat the liquid hydrogen or BOG; the hydrogen fuel engine is connected to the hydrogen generator via a drive shaft; the hydrogen generator is connected in sequence to the ship's electrical grid and propulsion motor via cables; the propulsion motor is connected to the propeller via a drive shaft.

[0014] In the methanol production system, the CO2 pump is placed at the bottom of the C-type tank and connected to the methanol production unit via a pipeline; the liquid hydrogen tank is connected in sequence to the compressor, BOG valve, and methanol production unit via pipelines; the methanol production unit is connected to the methanol tank via a pipeline. The methanol production unit is located on the deck aft of the ship's sterncastle, and the methanol tank is located below the deck at the stern. The function of the methanol production unit is to produce methanol from the CO2 in the C-type tank and the BOG in the liquid hydrogen tank under the action of a catalyst.

[0015] In the methanol supply system, the methanol pump is placed at the bottom of the methanol tank and connected to the II heating unit via a pipeline; the II heating unit is connected in sequence to the II fuel valve group unit and the methanol fuel engine via pipelines. The function of the II heating unit is to heat the methanol. The methanol fuel engine is connected to the methanol generator via a drive shaft. The methanol generator is connected in sequence to the ship's electrical grid and the propulsion motor via cables. The propulsion motor is connected to the propeller via a drive shaft.

[0016] In the CO2 insulation system, the liquid hydrogen tank is connected to the compressor and heat exchanger in sequence via pipelines; the heat exchanger is connected to the circulating pump and C-type tank in sequence via pipelines, wherein the C-type tank is placed on the aft deck of the ship's sterncastle.

[0017] Furthermore, the present invention is equipped with three hydrogen fuel engines and one methanol fuel engine, enabling the use of multiple fuels.

[0018] This invention has the following three main applications in ship navigation:

[0019] In the first scenario, the liquid hydrogen ship is sailing normally (i.e., in good sea conditions), with a relatively high speed and a large propulsion load:

[0020] The hydrogen fuel cell engine prioritizes the use of boil-off gas (BOG) generated in the liquid hydrogen tank during ship voyage. The BOG in the liquid hydrogen tank is compressed and enters a heat exchanger, transferring its cooling capacity to the refrigerant. The refrigerant circulates within the pipes of the C-type tank, exchanging heat with the CO2 in the C-type tank, thus keeping the CO2 cool. The heated BOG is then piped to Heating Unit I, where it is heated to the appropriate intake temperature for the hydrogen fuel cell engine. Finally, it is supplied to the hydrogen fuel cell engine for combustion via Fuel Valve Unit I. Since the hydrogen fuel cell engine can burn all the BOG in this scenario, leaving no surplus, the BOG valve is closed, and all BOG is supplied to the hydrogen fuel cell engine.

[0021] When the amount of BOG (Boiler Air) produced is insufficient to meet the fuel requirements of the hydrogen fuel cell engine, some of the liquid hydrogen in the liquid hydrogen tank is pumped to Heating Unit I. The liquid hydrogen is heated to a suitable intake temperature for the hydrogen fuel cell engine and then passed through Fuel Valve Group I before being supplied to the engine for combustion. Finally, the hydrogen fuel cell engine drives a connected hydrogen generator to produce electricity. This electricity is transmitted and distributed through the ship's electrical network and ultimately supplied to the propulsion motor. The propulsion motor converts the electrical energy into mechanical energy to drive the propeller, thus propelling the ship.

[0022] In the second scenario, during rough seas or when the ship is maneuvering at a low speed, the ship's propulsion load is low:

[0023] At this point, due to the reduced speed, the amount of liquid hydrogen fuel cell (BOG) burned by the hydrogen fuel cell engine will be significantly reduced. Furthermore, liquid hydrogen has a low density, and the ship is lightweight; wind and waves will cause the liquid hydrogen ship to rock violently. During this rocking process, some of the mechanical energy generated by the liquid hydrogen in the liquid hydrogen tank is converted into heat energy, further increasing BOG production, resulting in a BOG surplus. This surplus BOG is then transferred to the methanol production unit to produce methanol. The process is as follows: the BOG valve opens, and the BOG in the liquid hydrogen tank is transported by the compressor to the heat exchanger for preliminary heating. A portion of the pre-heated BOG is then piped to Heating Unit I for further heating to the appropriate intake temperature for the hydrogen fuel cell engine. Finally, it is transported to the hydrogen fuel cell engine for combustion through Fuel Valve Unit I. The surplus BOG is then transferred to the methanol production unit via the BOG valve. Simultaneously, the CO2 pump transports CO2 from Tank C to the methanol production unit. In the methanol production unit, BOG and CO2 react under certain conditions to produce methanol. The produced methanol is then piped to the methanol tank for storage.

[0024] In the third scenario, when the ship exits the second scenario and enters normal navigation (i.e., when sea conditions are good), the liquid hydrogen ship has a higher speed, increasing the ship's propulsion load.

[0025] At this time, the hydrogen fuel engine prioritizes the use of BOG generated in the liquid hydrogen tank during the ship's voyage. The BOG supply process is as follows: the BOG in the liquid hydrogen tank is transported to the heat exchanger via the compressor. The BOG undergoes preliminary heating in the heat exchanger. After preliminary heating, the BOG is transported through pipelines to Heating Unit I for further heating. The BOG is heated to the appropriate intake temperature of the hydrogen fuel engine in Heating Unit I and is finally transported to the hydrogen fuel engine for combustion via Fuel Valve Group Unit I.

[0026] Since a certain amount of methanol is already stored in the methanol tank during rough seas or when the ship is maneuvering, when the production of BOG (Bottle-Off Gas) cannot meet the fuel requirements of the ship's main engine, the energy released by burning methanol is used to provide power to the ship. The process is as follows:

[0027] The methanol pump pumps methanol from the methanol tank through pipelines to Heating Unit II. In Heating Unit II, the methanol is heated to a suitable intake temperature for the methanol-fueled engine, and then delivered to the engine for combustion via Fuel Valve Unit II. The methanol-fueled engine then drives a connected methanol generator to produce electricity. This electricity is transmitted and distributed through the ship's electrical network, ultimately supplying the propulsion motor. The propulsion motor converts the electrical energy into mechanical energy to drive the propeller, thus propelling the ship.

[0028] In the third scenario, if the ship's voyage lasts for a long time, the stored methanol will be consumed in large quantities. When the methanol level in the methanol tank is low, some of the liquid hydrogen in the liquid hydrogen tank will be vaporized and supplied to the hydrogen fuel engine for combustion. The process is as follows: some of the liquid hydrogen in the liquid hydrogen tank is pumped to heating unit I. The liquid hydrogen enters heating unit I and is heated to a suitable intake temperature for the hydrogen fuel engine. Finally, it is delivered to the hydrogen fuel engine for combustion through fuel valve group unit I. The hydrogen fuel engine then drives the connected hydrogen generator to generate electricity. The generated electricity is transmitted and distributed through the ship's electrical network. Finally, the electricity is delivered to the propulsion motor, which converts the electrical energy into mechanical energy to drive the propeller, thereby propelling the ship.

[0029] If the liquid hydrogen ship encounters rough seas or maneuvering during its voyage, the second scenario will be implemented; once the ship exits the rough seas or maneuvering conditions and enters a period of good sea conditions or non-maneuvering navigation, the liquid hydrogen ship will proceed with normal navigation, and the third scenario will be implemented.

[0030] Beneficial effects of the invention

[0031] 1. This invention reacts excess liquid hydrogen gas (BOG) from a liquid hydrogen ship with almost "waste" CO2 during rough seas or when the ship is navigating by motor to produce methanol, which is then stored. When the amount of BOG is insufficient to meet the needs of the main engine during normal navigation, the methanol is used as fuel for the ship. This not only eliminates the need for expensive and costly BOG reliquefaction equipment, but also effectively solves the problem of excess liquid hydrogen gas during rough seas or when the ship is navigating by motor.

[0032] 2. This invention utilizes the cold energy of liquid hydrogen BOG to keep CO2 in the C-type tank on a liquid hydrogen ship cool, thus avoiding the generation of CO2 BOG and making reasonable use of the cold energy of liquid hydrogen BOG. Attached Figure Description

[0033] Figure 1 This is a system diagram of the present invention;

[0034] Figure 2 This is a schematic diagram of a liquid hydrogen ship;

[0035] Figure 3 This is a diagram showing the location of the C-type tank;

[0036] In the attached diagram: 1. Liquid hydrogen tank; 2. Compressor; 3. Liquid hydrogen pump; 4. Heat exchanger; 5. Heating unit I; 6. Fuel valve assembly unit I; 7. Hydrogen fuel engine; 8. Hydrogen generator; 9. Ship electrical grid; 10. Propulsion motor; 11. Circulation pump; 12. BOG valve; 13. Type C tank; 14. CO2 pump; 15. Methanol production unit; 16. Methanol tank; 17. Methanol pump; 18. Heating unit II; 19. Fuel valve assembly unit II; 20. Methanol fuel engine; 21. Methanol generator. Detailed Implementation

[0037] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0038] like Figure 1 As shown, a system for treating excess vaporized gas in a liquid hydrogen ship using methanol production is disclosed. The system includes a hydrogen fuel supply system, a methanol production system, a methanol supply system, and a CO2 cooling system.

[0039] The hydrogen fuel supply system includes: a liquid hydrogen tank 1, a compressor 2, a liquid hydrogen pump 3, a heat exchanger 4, a heating unit I 5, a fuel valve group unit I 6, a hydrogen fuel engine 7, a hydrogen generator 8, a shipboard electrical grid 9, and a propulsion motor 10.

[0040] The methanol production system includes: liquid hydrogen chamber 1, compressor 2, BOG valve 12, methanol production unit 15, C-type tank 13, CO2 pump 14, and methanol chamber 16.

[0041] The methanol supply system includes: methanol tank 16, methanol pump 17, II heating unit 18, II fuel valve group unit 19, methanol fuel engine 20, methanol generator 21, ship electrical grid 9, and propulsion motor 10.

[0042] The CO2 insulation system includes: liquid hydrogen chamber 1, compressor 2, heat exchanger 4, circulating pump 11, and C-type tank 13.

[0043] In the hydrogen fuel supply system, the liquid hydrogen pump 3 is placed at the bottom of the liquid hydrogen tank 1 and connected to the I heating unit 5 via a pipeline; at the same time, the liquid hydrogen tank 1 is connected to the compressor 2, heat exchanger 4, and I heating unit 5 in sequence via another pipeline; the I heating unit 5 is connected to the I fuel valve group unit 6 and the hydrogen fuel engine 7 in sequence via pipelines, and the function of the I heating unit 5 is to heat the liquid hydrogen or BOG; the hydrogen fuel engine 7 is connected to the hydrogen generator 8 via a drive shaft; the hydrogen generator 8 is connected to the ship's electrical grid 9 and propulsion motor 10 in sequence via cables; the propulsion motor 10 is connected to the propeller via a drive shaft.

[0044] In the methanol production system, the CO2 pump 14 is placed at the bottom of the C-type tank 13 and connected to the methanol production unit 15 via a pipeline; the liquid hydrogen tank 1 is connected in sequence to the compressor 2, the BOG valve 12, and the methanol production unit 15 via pipelines; the methanol production unit 15 is connected to the methanol tank 16 via a pipeline, wherein the methanol production unit 15 is placed on the deck aft of the ship's sterncastle, and the methanol tank 16 is placed below the deck at the stern. The function of the methanol production unit 15 is to produce methanol from the CO2 in the C-type tank 13 and the BOG in the liquid hydrogen tank 1 under the action of a catalyst.

[0045] In the methanol supply system, the methanol pump 17 is placed at the bottom of the methanol tank 16 and connected to the II heating unit 18 via a pipe; the II heating unit 18 is connected in sequence to the II fuel valve group unit 19 and the methanol fuel engine 20 via pipes, and the function of the II heating unit 18 is to heat the methanol; the methanol fuel engine 20 is connected to the methanol generator 21 via a drive shaft; the methanol generator 21 is connected in sequence to the ship's electrical grid 9 and the propulsion motor 10 via cables; the propulsion motor 10 is connected to the propeller via a drive shaft.

[0046] In the CO2 insulation system, the liquid hydrogen tank 1 is connected to the compressor 2 and the heat exchanger 4 in sequence through pipes; the heat exchanger 4 is connected to the circulating pump 11 and the C-type tank 13 in sequence through pipes, wherein the C-type tank 13 is placed on the aft deck of the ship's sterncastle.

[0047] Furthermore, the present invention is equipped with three hydrogen fuel engines 7 and one methanol fuel engine 20, which can realize the use of multiple fuels.

[0048] To explain in detail how the system operates, this invention will describe it from the following three perspectives.

[0049] In the first scenario, the liquid hydrogen ship is sailing normally (i.e., in good sea conditions), with a relatively high speed and a large propulsion load:

[0050] The hydrogen fuel cell engine 7 prioritizes the combustion gas (BOG) generated in the liquid hydrogen tank 1 during ship navigation. The BOG in the liquid hydrogen tank 1 first enters the compressor 2 through a pipeline for pressurization. The pressurized BOG is then transported to the heat exchanger 4 through a pipeline. In the heat exchanger 4, the BOG undergoes preliminary heating, transferring some of its cooling capacity to the refrigerant. The refrigerant circulates through the pipeline passing through the C-type tank 13, exchanging heat with the CO2 in the C-type tank 13. This process keeps the CO2 cool and prevents it from evaporating due to heat absorption, which could cause excessive pressure in the C-type tank 13. After preliminary heat exchange, the BOG is transported through a pipeline to the I heating unit 5 for further heating. In the I heating unit 5, the BOG is heated to a suitable intake temperature for the hydrogen fuel cell engine 7, and then transported to the hydrogen fuel cell engine 7 for combustion via the I fuel valve group unit 6. Since the hydrogen fuel cell engine 7 can consume all the BOG in this scenario, with no surplus, the BOG valve 12 is closed, and all BOG is supplied to the hydrogen fuel cell engine 7. When the amount of BOG generated is insufficient to meet the fuel requirements of the hydrogen fuel engine 7, some of the liquid hydrogen in the liquid hydrogen tank 1 is pumped by the liquid hydrogen pump 3 to the heating unit 5. The liquid hydrogen is heated to a suitable intake temperature for the hydrogen fuel engine 7 in the heating unit 5, and finally delivered to the hydrogen fuel engine 7 for combustion after passing through the fuel valve group unit 6. Finally, the hydrogen fuel engine 7 drives the connected hydrogen generator 8 to generate electricity. The generated electricity is transmitted and distributed through the ship's electrical grid 9, and finally delivered to the propulsion motor 10. The propulsion motor 10 converts the electrical energy into mechanical energy to drive the propeller, thereby propelling the ship.

[0051] In the second scenario, during rough seas or when the ship is maneuvering at a low speed, the ship's propulsion load is low:

[0052] At this point, due to the reduced speed, the amount of liquid hydrogen (BOG) burned by the hydrogen fuel engine 7 will be greatly reduced. Furthermore, liquid hydrogen has a low density and the ship is lightweight, so wind and waves will cause the liquid hydrogen ship to rock violently. During this rocking process, some of the mechanical energy generated by the liquid hydrogen in the liquid hydrogen tank 1 is converted into heat energy, further increasing the amount of BOG produced, resulting in a BOG surplus. In this case, the surplus BOG is transported to the methanol production unit 15 to produce methanol. The process is as follows: BOG valve 12 is opened, and the BOG in the liquid hydrogen tank 1 first enters the compressor 2 through a pipeline for pressurization. The pressurized BOG is then transported through a pipeline to the heat exchanger 4, where it undergoes preliminary heating. A portion of the pre-heated BOG is then transported through a pipeline to the I heating unit 5 for further heating to a suitable intake temperature for the hydrogen fuel engine 7. Finally, it is transported to the hydrogen fuel engine 7 for combustion through the I fuel valve group unit 6. Excess BOG is transported to methanol production unit 15 through BOG valve 12. At the same time, CO2 pump 14 transports CO2 from C-type tank 13 to methanol production unit 15. In methanol production unit 15, BOG and CO2 react under certain conditions to produce methanol. The produced methanol is transported to methanol tank 16 for storage through pipeline.

[0053] In the third scenario, when the ship exits the second scenario and enters normal navigation (i.e., when sea conditions are good), the liquid hydrogen ship has a higher speed, increasing the ship's propulsion load.

[0054] At this time, the hydrogen fuel engine 7 prioritizes the use of BOG generated by the liquid hydrogen tank 1 during the ship's voyage. The BOG supply process is as follows: the BOG in the liquid hydrogen tank 1 first enters the compressor 2 through a pipeline for pressurization. The pressurized BOG is then transported to the heat exchanger 4 through a pipeline. The BOG undergoes preliminary heating in the heat exchanger 4. The pre-heated BOG is then transported to the I heating unit 5 for reheating. The BOG is heated to the appropriate intake temperature of the hydrogen fuel engine 7 in the I heating unit 5, and finally delivered to the hydrogen fuel engine 7 for combustion via the I fuel valve group unit 6.

[0055] Since a certain amount of methanol is stored in the methanol tank 16 during rough seas or when the ship is maneuvering (the amount of methanol depends on the duration of the rough seas or maneuvering), when the production of BOG (Boat Gas) cannot meet the ship's fuel needs, the ship is powered by burning methanol. The process is as follows: the methanol pump 17 transports the methanol in the methanol tank 16 through pipelines to the II heating unit 18. The methanol is heated in the II heating unit 18 to a suitable intake temperature for the methanol fuel engine 20, and finally transported to the methanol fuel engine 20 for combustion via the II fuel valve group unit 19. The methanol fuel engine 20, after combustion, drives the connected methanol generator 21 to generate electricity. The generated electrical energy is transmitted and distributed through the ship's electrical grid 9, and finally delivered to the propulsion motor 10. The propulsion motor 10 converts the electrical energy into mechanical energy to drive the propeller, thereby propelling the ship.

[0056] In the third scenario, if the ship's voyage lasts for a long time, the stored methanol will be consumed in large quantities. When the methanol level in the methanol tank 16 is low, some of the liquid hydrogen in the liquid hydrogen tank 1 will be vaporized and supplied to the hydrogen fuel engine 7 for combustion. The process is as follows: some of the liquid hydrogen in the liquid hydrogen tank 1 is transported to the I heating unit 5 by the liquid hydrogen pump 3. The liquid hydrogen enters the I heating unit 5 and is heated to a suitable intake temperature for the hydrogen fuel engine 7. Finally, it is transported to the hydrogen fuel engine 7 for combustion through the I fuel valve group unit 6. The hydrogen fuel engine 7 drives the connected hydrogen generator 8 to generate electricity. The generated electrical energy is transmitted and distributed through the ship's electrical grid 9. Finally, the electricity is delivered to the propulsion motor 10. The propulsion motor 10 converts the electrical energy into mechanical energy to drive the propeller, thereby propelling the ship.

[0057] If the liquid hydrogen ship encounters rough seas or maneuvering during its voyage, the second scenario will be implemented; once the ship exits the rough seas or maneuvering conditions and enters a period of good sea conditions or non-maneuvering navigation, the liquid hydrogen ship will proceed with normal navigation, and the third scenario will be implemented.

[0058] In the first scenario, there is no methanol production process, and the CO2 in tank 13 is not consumed. To prevent the CO2 in tank 13 from absorbing heat from the outside and generating BOG (Boiled Organic Gas), the CO2 needs to be kept cool. The cooling process involves increasing the power of the circulation pump 11, causing the refrigerant to circulate within the pipes of tank 13 and exchange heat with the CO2 in tank 13, thus maintaining the CO2 in tank 13 in a liquid state. In the second scenario, there is a methanol production process, and the amount of CO2 in tank 13 decreases. Therefore, the cooling required to maintain it in a liquid state also decreases accordingly. In this case, the power of the circulation pump 11 can be appropriately reduced, allowing the refrigerant to circulate within the pipes of tank 13 and exchange heat with the CO2 in tank 13, thus maintaining the CO2 in tank 13 in a liquid state. In this invention, the power of the circulation pump 11 decreases accordingly as the amount of CO2 decreases.

[0059] When the liquid hydrogen ship reaches the end of its voyage and docks, it will need to refuel with CO2 at the port because the ship will consume CO2 from tank 13 (C-type tank) to produce methanol during the voyage. Since CO2 emissions from ships and factories must be captured by carbon capture devices and transported to the port for centralized unloading, the accumulated CO2 reserves are increasing. However, ports cannot utilize this large amount of CO2, resulting in a significant amount of "CO2 waste" in the future. Therefore, obtaining CO2 from ports will be very easy in the future.

[0060] Further explanation of the beneficial effects of this invention: During rough seas or maneuvering, the amount of bulky gas (BOG) burned by the main engine of a liquid hydrogen ship is significantly reduced due to the lower speed of the vessel. Furthermore, because liquid hydrogen has a low density, the draft of a fully loaded liquid hydrogen ship is shallow, and the hull rocks violently in rough seas. During this rocking motion, some of the mechanical energy generated by the liquid hydrogen in the liquid hydrogen tank 1 is converted into heat energy, further increasing the amount of BOG produced. Therefore, the amount of BOG burned by the hydrogen fuel engine 7 is greatly reduced. Based on these two reasons, an excess of BOG will occur during rough seas or maneuvering. The usual method for handling excess BOG on liquid hydrogen ships is to liquefy it using a reliquefaction device and store it in the liquid hydrogen tank 1. However, due to the extremely low storage temperature of liquid hydrogen, the requirements for the liquefaction device are very high, and the operating cost of the device is also very high. Therefore, the cost of BOG reliquefaction is very high. Since the above methods have obvious drawbacks, this invention carries a certain amount of CO2 and uses excess BOG to react with almost "waste" CO2 to produce methanol during windy and rough weather or when the ship is navigating by motor. The produced methanol is stored in the methanol tank 16. When the ship is navigating normally and the amount of BOG cannot meet the needs of the main engine, the methanol is used as fuel for the ship. This not only effectively solves the problem of excess BOG when the liquid hydrogen ship is under low load, but also eliminates the need for the ship to be equipped with expensive and costly BOG reliquefaction equipment. It has high innovation and practical value.

[0061] The above description is merely a preferred embodiment of the present invention. The specific embodiments described herein are only for explaining the present invention and are not intended to limit the present invention. It should be noted that those skilled in the art can make several improvements and modifications without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A system for treating excess vaporized gas from methanol in a liquid hydrogen ship, characterized in that: This system includes a hydrogen fuel supply system, a methanol production system, a methanol supply system, and a CO2 cooling system. The methanol production system includes: a liquid hydrogen chamber (1), a compressor (2), a BOG valve (12), a methanol production unit (15), a C-type tank (13), a CO2 pump (14), and a methanol chamber (16). The CO2 pump (14) is placed at the bottom of the C-type tank (13) and connected to the methanol production unit (15) via a pipeline. The liquid hydrogen chamber (1) is connected in sequence to the compressor (2), the BOG valve (12), and the methanol production unit (15) via pipelines. The methanol production unit (15) is connected to the methanol chamber (16) via a pipeline. The CO2 insulation system includes: a liquid hydrogen chamber (1), a compressor (2), a heat exchanger (4), a circulating pump (11), and a C-type tank (13). The liquid hydrogen chamber (1) is connected in sequence to the compressor (2) and the heat exchanger (4) via pipelines; the heat exchanger (4) is connected in sequence to the circulating pump (11) and the C-type tank (13) via pipelines.

2. The system for producing and treating excess vapor from methanol in a liquid hydrogen ship according to claim 1, characterized in that: The engine set includes three hydrogen fuel engines (7) and one methanol fuel engine (20), both of which are dual-fuel engines.

3. The system for producing and treating excess vapor from methanol in a liquid hydrogen ship according to claim 1, characterized in that: The C-type tank (13) is placed on the aft deck of the ship's sterncastle.

4. A system for producing and treating excess vaporized gas from methanol in a liquid hydrogen ship according to claim 1, characterized in that: The methanol tank (16) is located below the deck at the stern of the ship.

5. A system for producing and treating excess vaporized gas from methanol in a liquid hydrogen ship according to claim 1, characterized in that: The methanol production unit (15) is placed on the aft deck of the ship's sterncastle.

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