Device for reducing evaporation rate of liquid hydrogen cabin of ship

Abstract

The invention relates to the field of ship liquid hydrogen transportation, and discloses a device for reducing the evaporation rate of a ship liquid hydrogen cabin. The device is arranged based on a liquid hydrogen cabin and an LNG tank and comprises a cooling coil arranged outside the liquid hydrogen cabin, an inlet of the cooling coil is communicated with the liquid hydrogen cabin and the LNG tank, and an outlet of the cooling coil is communicated with the LNG tank and the outside of the device; hydrogen evaporation gas enters a cooling coil from a liquid hydrogen cabin to cool the liquid hydrogen cabin, and then flows out of the device; according to the second cooling channel, LNG evaporation gas enters the cooling coil from the LNG tank to cool the liquid hydrogen cabin and then flows out of the device or flows back to the LNG tank. According to the third cooling channel, LNG liquid enters the cooling coil from the LNG tank to cool the liquid hydrogen cabin, and then the liquid hydrogen cabin flows out of the outflow device or flows back into the LNG tank. According to the device, the cargo evaporation rate in the liquid hydrogen cabin is effectively reduced, hydrogen evaporation gas and LNG cold energy are fully utilized, and the transportation cost and the fuel cost of the liquid hydrogen transport ship are greatly reduced.

Description

Technical Field

[0001] The present application relates to the field of liquid hydrogen transportation in ships, and more specifically, it relates to a device for reducing the evaporation rate of liquid hydrogen tanks in ships. Background Art

[0002] Hydrogen energy is a secondary energy source that is abundant in source, green, low-carbon and widely used. Liquid hydrogen tankers can transport hydrogen energy efficiently. The temperature of liquid hydrogen is as low as -253℃. During transportation, there is a large temperature difference between liquid hydrogen cargo and the external environment, which causes the liquid hydrogen cargo to evaporate due to heat, resulting in the loss of liquid hydrogen cargo. Therefore, it is particularly important to effectively reduce the evaporation rate of liquid hydrogen tanks.

[0003] There are two main ways to reduce the evaporation rate of liquid hydrogen tanks in the prior art: one is to reduce the evaporation rate by designing the liquid hydrogen tank body and the insulation layer structure. However, due to the limitations of the performance of insulating materials, facing the extremely low temperature of liquid hydrogen, conventional insulation material coating methods have been difficult to further reduce the evaporation rate. Usually, vacuum insulation or a combination of vacuum insulation + insulation material coating is selected; the other is to change the temperature field distribution outside the liquid hydrogen tank, increase the external low-temperature medium for cooling, and reduce the temperature difference between the liquid hydrogen tank and the external environment, thereby reducing the evaporation rate. The more commonly used method is to inject liquid nitrogen to isolate it from the external environment. This method requires long-term consumption of a large amount of liquid nitrogen, which is a huge challenge to the source and cost of liquid nitrogen supply on ships.

[0004] The Chinese patent with publication number CN117662974A discloses a steam cold shield system for large ship-borne liquid hydrogen tanks and its working method, which dynamically switches the steam cold shield operation mode in real time according to the marine ambient temperature and the actual operating conditions of the liquid hydrogen tank; it operates in a two-stage series passive steam cold shield mode in a low heat leakage scenario, and operates in an active and passive combination steam cold shield mode in a high heat leakage scenario, thereby effectively extending the liquid hydrogen storage period while saving refrigerator energy consumption. However, in this method, the passive cold preservation effect of hydrogen evaporation gas alone is limited, and if the active and passive combination steam cold shield mode is to be operated, an active refrigeration system needs to be set up, and a special cold shielding layer needs to be manufactured, which makes the system complex and costly.

[0005] Among the above measures, whether liquid nitrogen is used for cold preservation or active refrigeration of hydrogen evaporated gas, a large amount of cryogenic medium or refrigeration energy consumption is involved. The ship power station is small and it is difficult to store liquid nitrogen medium, so there are great difficulties and inconveniences in its application in the ship field.

[0006] Therefore, how to develop a device that can effectively reduce the evaporation rate of the ship's liquid hydrogen tank based on the existing conditions of liquid hydrogen transport ships is of great significance to the development of the field of ship liquid hydrogen transportation. Summary of the invention

[0007] For liquid hydrogen transport ships, the sea transportation cycle is long and the evaporation of liquid hydrogen cargo cannot be ignored. Therefore, the invention object of this application is to provide a device with simple structure, low cost and good refrigeration effect to reduce the evaporation rate of the liquid hydrogen tank.

[0008] In order to achieve the above-mentioned purpose of the invention, the present invention provides a device for reducing the evaporation rate of a liquid hydrogen tank of a ship, which adopts the following technical solution:

[0009] The first invention provides a device for reducing the evaporation rate of a liquid hydrogen tank of a ship, which is arranged based on the liquid hydrogen tank and the LNG tank of the liquid hydrogen transport ship, and includes two or more groups of cooling coils arranged outside the liquid hydrogen tank, the inlet of the cooling coil is connected to the liquid hydrogen tank and the LNG tank, and the outlet of the cooling coil is connected to the LNG tank and the outside of the device;

[0010] The device is provided with three cooling paths for cooling the liquid hydrogen cabin, including:

[0011] Cooling path 1: Hydrogen evaporated gas enters the cooling coil from the liquid hydrogen tank to cool the liquid hydrogen tank, and then flows out of the device from the outlet of the cooling coil;

[0012] Cooling path 2: LNG evaporated gas enters the cooling coil from the LNG tank to cool the liquid hydrogen tank, and then flows out of the device from the outlet of the cooling coil or flows back into the LNG tank;

[0013] Cooling path three: LNG liquid enters the cooling coil from the LNG tank to cool the liquid hydrogen tank, and then flows out of the device from the cooling coil outlet or flows back to the LNG tank.

[0014] Furthermore, the liquid hydrogen tank comprises an inner wall and an outer wall of the liquid hydrogen tank, the interlayer between the inner wall and the outer wall of the liquid hydrogen tank adopts a vacuum insulation form, and an insulating coating material is arranged on the outer side of the outer wall of the liquid hydrogen tank.

[0015] Furthermore, the cooling coil is arranged close to the outer wall of the liquid hydrogen tank, and the cooling coil includes an upper cooling coil and a lower cooling coil, and the upper cooling coil and the lower cooling coil are respectively arranged at the upper part and the lower part of the liquid hydrogen tank.

[0016] Furthermore, a plurality of control valves for hydrogen boil-off gas are provided at the inlet of the cooling coil, including a hydrogen lower cooling coil inlet control valve, a hydrogen upper cooling coil inlet control valve and a hydrogen boil-off gas main valve connected to the liquid hydrogen tank, which are used to control the opening and closing of the hydrogen boil-off gas supply to control the working process of the cooling passage one.

[0017] Furthermore, the LNG tank includes an inner wall of the LNG tank and an insulation layer of the LNG tank, and a plurality of control valves for LNG are also provided at the inlet of the cooling coil, including an LNG lower cooling coil inlet control valve, an LNG upper cooling coil inlet control valve and an LNG evaporated gas main valve provided at the inlet of the cooling coil, which are used to control the opening and closing of the LNG evaporated gas supply to control the working process of the cooling passage two.

[0018] Furthermore, the LNG tank includes an LNG tank inner wall and an LNG tank insulation layer, and a plurality of control valves for LNG are also provided at the inlet of the cooling coil, including an LNG lower cooling coil inlet control valve, an LNG upper cooling coil inlet control valve and an LNG liquid main valve provided at the inlet of the cooling coil, which are used to control the opening and closing of the LNG liquid supply to control the working process of the cooling passage three.

[0019] Furthermore, a temperature sensor is provided at the outlet of the cooling coil for monitoring the temperature state of the cooling coil outlet and adjusting the control valve group according to temperature changes, and a cooling coil outlet control valve is also provided at the outlet of the cooling coil.

[0020] Furthermore, an LNG reflux pressure relief valve is provided on the passage connecting the cooling coil outlet and the LNG tank, for opening or closing the reflux passage of LNG liquid or LNG evaporated gas.

[0021] Furthermore, the device also includes a heating device, a compressor and an air supply valve; the heating device, the compressor and the air supply valve are all arranged on a passage connecting the outlet of the cooling coil and the outside of the device, the heating device is used to heat the evaporated gas at the outlet of the cooling coil to a normal temperature state, so as to facilitate subsequent use as fuel by hydrogen or natural gas users; the compressor is used to pressurize normal temperature hydrogen or natural gas or a mixture of the two for use by hydrogen or natural gas users; the air supply valve is used to supply normal temperature hydrogen or natural gas or a mixture of the two without pressurization for use by hydrogen or natural gas users.

[0022] In a second aspect, the present application provides a working method of the device described in the first aspect, including the following three working states:

[0023] Working state 1: When the ship uses hydrogen as ship fuel, the hydrogen boil-off gas is used to reduce the evaporation rate of the liquid hydrogen tank. After the hydrogen boil-off gas passes through the hydrogen boil-off gas main valve, it passes through the hydrogen lower cooling coil inlet control valve and the hydrogen upper cooling coil inlet control valve respectively, and enters the upper cooling coil and the lower cooling coil, thereby realizing the cooling of the liquid hydrogen tank;

[0024] Working state 2: When the ship uses LNG boil-off gas as ship fuel, the LNG boil-off gas is used to reduce the evaporation rate of the liquid hydrogen tank. After passing through the LNG boil-off gas main valve, the LNG boil-off gas passes through the LNG lower cooling coil inlet control valve and the LNG upper cooling coil inlet control valve respectively, and enters the upper cooling coil and the lower cooling coil, thereby realizing cooling of the liquid hydrogen tank;

[0025] Working state three: When the ship does not use hydrogen or LNG boil-off gas as fuel, and regardless of whether the ship uses LNG liquid as fuel, LNG liquid can be directly extracted to reduce the evaporation rate of the liquid hydrogen tank. An LNG pump is installed in the LNG tank to pump out LNG liquid. After the LNG liquid passes through the LNG liquid main valve, it passes through the LNG lower cooling coil inlet control valve and the LNG upper cooling coil inlet control valve respectively, and then enters the upper cooling coil and the lower cooling coil, thereby achieving cooling of the liquid hydrogen tank.

[0026] Compared with the prior art, the device of the present invention has the following beneficial effects:

[0027] 1. Make full use of the cold energy of hydrogen and LNG fuel in liquid hydrogen carriers, and take cold preservation measures for liquid hydrogen tanks by using the evaporated gas, LNG liquid, or LNG evaporated gas generated during the transportation of liquid hydrogen by liquid hydrogen carriers as cold sources. The cooling coil is surrounded by the metal outer wall of the vacuum liquid hydrogen tank to reduce the temperature of the metal outer wall of the liquid hydrogen tank, thereby reducing the temperature difference between the inner wall and the outer wall of the liquid hydrogen tank, greatly reducing the heat leakage from the external environment, and reducing the evaporation rate of liquid hydrogen cargo and cargo loss. Compared with the device for reducing the evaporation rate of liquid hydrogen tanks in the prior art, this device does not need to use other cryogenic working fluids such as liquid nitrogen or a special hydrogen refrigeration system, and can make full use of the cold energy of the ship's cryogenic fuel. The implementation method is simple and the implementation cost is low.

[0028] 2. By dividing the evaporative gas cooling coil into an upper cooling coil and a lower cooling coil, the cooling coil is placed close to the metal outer wall of the vacuum liquid hydrogen tank, and with the help of the good thermal conductivity of the metal outer wall of the liquid hydrogen tank, a small number of cooling coils are used to cool the entire metal outer wall to form a complete low-temperature layer. When the cold energy is insufficient, the lower cooling coil is given priority to ensure the cooling effect of the liquid hydrogen cargo at the bottom of the liquid hydrogen tank and reduce the generation of hydrogen evaporation.

[0029] 3. The device of the invention combines the characteristics of ship fuel use and is compatible with three cooling methods: liquid hydrogen boil-off gas, LNG liquid, and LNG boil-off gas. Through the outlet temperature sensor and flow regulation of the control valve, three different levels of liquid hydrogen tank evaporation rate reduction effects can be achieved:

[0030] (1) During the cooling period using LNG boil-off gas, the temperature difference between the inner and outer walls of the liquid hydrogen tank is controlled between 150 and 200°C.

[0031] (2) During the use of LNG liquid cooling, the temperature difference between the inner wall and the outer wall of the liquid hydrogen tank is controlled between 90 and 150°C.

[0032] (3) During the cooling period using liquid hydrogen boil-off gas, the temperature difference between the inner wall and the outer wall of the liquid hydrogen tank is controlled between 50 and 150°C.

[0033] 4. The present invention realizes the extraction of hydrogen boil-off gas and LNG boil-off gas through the same type of compressor, avoiding the need to equip two sets of independent hydrogen compressors and LNG boil-off gas compressors. At the same time, it can also realize the extraction of mixed gas as fuel after hydrogen fuel and LNG fuel are mixed in a certain proportion, and realize the same type of compressor to control the liquid hydrogen tank pressure and the LNG tank pressure at the same time, greatly reducing the compressor equipment configuration cost and having a fuel mixing function.

[0034] 5. When the ship is not sailing or does not use hydrogen or LNG fuel for other reasons, the LNG pump can be used to directly extract LNG to cool the outer wall of the vacuum sandwich liquid hydrogen tank, and the cooled LNG liquid and evaporated gas can be returned to the LNG tank, realizing active cooling of the liquid hydrogen tank to reduce the evaporation rate without wasting LNG fuel.

[0035] In summary, through the use of the above measures, the evaporation rate of liquid hydrogen cargo in the liquid hydrogen tank of the liquid hydrogen transport ship can be effectively reduced, the compressor equipment cost can be reduced, and the hydrogen boil-off gas and LNG cold energy can be fully utilized, saving the heat energy required for the ship to heat the hydrogen boil-off gas or LNG, reducing the amount of cargo transportation losses caused by hydrogen boil-off gas as fuel, and greatly reducing the transportation cost and fuel cost of liquid hydrogen transport ships. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 : Schematic diagram of the device for reducing the evaporation rate of the liquid hydrogen tank of a ship in this embodiment.

[0037] Figure numerals: 1. Inner wall of liquid hydrogen tank; 2. Outer wall of liquid hydrogen tank; 3. Insulation coating material; 4. Upper cooling coil; 5. Lower cooling coil; 6. Hydrogen boil-off gas main valve; 7. Hydrogen lower cooling coil inlet control valve; 8. Hydrogen upper cooling coil inlet control valve; 9. Hydrogen boil-off gas main pipeline control valve; 10. Cooling coil outlet temperature sensor; 11. Boil-off gas main pipeline temperature sensor; 12. Heater; 13. Gas compressor; 14. Gas supply valve; 15. LNG tank interior Wall; 16. LNG tank insulation layer; 17. LNG pump; 18. LNG boil-off gas main valve; 19. LNG reflux valve; 20. LNG liquid main valve; 21. LNG lower cooling coil inlet control valve; 22. LNG upper cooling coil inlet control valve; 23. LNG boil-off gas main pipeline control valve; 24. LNG direct utilization control valve; 25. LNG boil-off gas direct utilization control valve; 26. Cooling coil outlet control valve, 27. LNG reflux pressure relief valve. DETAILED DESCRIPTION

[0038] The structure and effect of the present application are further described in detail below in conjunction with the embodiments. It is to be understood that the specific embodiments described herein are only used to explain the invention, rather than to limit the invention. It is also necessary to explain that, for ease of description, only the parts related to the invention rather than the entire structure are shown in the accompanying drawings.

[0039] Example

[0040] A device for reducing the evaporation rate of liquid hydrogen tanks in ships, referring to Figure 1 The device is arranged based on the liquid hydrogen tank and LNG tank of the liquid hydrogen transport ship. The liquid hydrogen tank is used to load liquid hydrogen cargo on the liquid hydrogen transport ship and use the hydrogen evaporated gas as ship fuel; the LNG tank is used to store or transport LNG and use LNG as ship fuel.

[0041] Reference Figure 1 The liquid hydrogen tank includes an inner wall 1 and an outer wall 2 of the liquid hydrogen tank. The outer wall 2 of the liquid hydrogen tank is made of a metal material that is resistant to low temperatures and has good thermal conductivity. The interlayer between the inner wall 1 and the outer wall 2 of the liquid hydrogen tank is insulated by vacuuming. If necessary, the vacuum interlayer can be filled with thermal insulation materials. An insulating coating material 3 is provided outside the liquid hydrogen tank. The insulating coating material 3 can be made of insulating materials such as polyurethane foam or polystyrene, and is coated on the outside of the outer wall 2 of the liquid hydrogen tank to enhance the thermal insulation performance of the liquid hydrogen tank.

[0042] Reference Figure 1 A cooling coil is provided between the outer wall 2 of the liquid hydrogen tank and the insulation layer, and the cooling coil is arranged close to the outer wall 2 of the liquid hydrogen tank. In a feasible implementation, the cooling coil can be divided into two or more groups. In this embodiment, two groups are taken as an example for explanation, that is, the cooling coil includes an upper cooling coil 4 and a lower cooling coil 5, and the upper cooling coil 4 and the lower cooling coil 5 are arranged at the upper part and the lower part of the liquid hydrogen tank, respectively. The cooling coil cools the outer wall 2 of the liquid hydrogen tank, and the insulation coating material 3 covers the cooling coil and the outer wall 2 of the liquid hydrogen tank as a whole. It is worth noting that the cooling coil does not need to wrap around the entire liquid hydrogen tank. It only needs to cover the local area of ​​the liquid hydrogen tank according to the design and calculation requirements, and the outer wall 2 of the liquid hydrogen tank is cooled as a whole by using the fast thermal conductivity of the metal of the outer wall 2 of the liquid hydrogen tank.

[0043] Reference Figure 1 At the inlet of the cooling coil, multiple groups of control valves for hydrogen boil-off gas are provided, including a hydrogen lower cooling coil inlet control valve 7, a hydrogen upper cooling coil inlet control valve 8 and a hydrogen boil-off gas main valve 6 connected to the liquid hydrogen tank, which are used to control the opening and closing of the hydrogen boil-off gas supply, and further adjust and control the temperature, pressure and flow of each group of cooling coils.

[0044] In one working state (when the ship uses hydrogen as the ship fuel, hydrogen boil-off gas is preferentially used to reduce the evaporation rate of the liquid hydrogen tank), the hydrogen boil-off gas passes through the hydrogen boil-off gas main valve 6, and then passes through the hydrogen lower cooling coil inlet control valve 7 and the hydrogen upper cooling coil inlet control valve 8 respectively, and enters the upper cooling coil 4 and the lower cooling coil 5, thereby realizing cooling of the liquid hydrogen tank.

[0045] Reference Figure 1 The LNG tank includes an LNG tank inner wall 15 and an LNG tank insulation layer 16. The LNG tank insulation layer 16 can be a vacuum insulation or insulation coating material. A plurality of control valves for LNG are also provided at the inlet of the cooling coil, including an LNG lower cooling coil inlet control valve 21, an LNG upper cooling coil inlet control valve 22 and an LNG boil-off gas main valve 18 provided at the inlet of the cooling coil, which are used to control the opening and closing of the LNG boil-off gas supply, and further adjust and control the temperature, pressure and flow of each group of cooling coils. If the LNG boil-off gas needs to be used directly, it can be used directly through the LNG boil-off gas direct use control valve 25.

[0046] In one working state (when the ship uses LNG boil-off gas as ship fuel, LNG boil-off gas is preferentially used to reduce the evaporation rate of the liquid hydrogen tank), the LNG boil-off gas passes through the LNG boil-off gas main valve 18, and then passes through the LNG lower cooling coil inlet control valve 21 and the LNG upper cooling coil inlet control valve 22 respectively, and enters the upper cooling coil 4 and the lower cooling coil 5, thereby achieving cooling of the liquid hydrogen tank.

[0047] Reference Figure 1 A temperature sensor 10 is also connected to the outlet of the cooling coil to monitor the outlet temperature of the cooling coil, so as to achieve the purpose of adjusting the control valve group through temperature changes. The temperature sensor 10 is connected to the cooling coil outlet control valve 26, and the cooling coil outlet control valve 26 adjusts the flow rate of each cooling group according to the outlet temperature sensor 10 to improve the cooling effect.

[0048] Reference Figure 1 The LNG tank is also provided with an LNG pump 17 and an LNG liquid main valve 20 connected to the LNG pump 17 .

[0049] In one working state (when the ship does not use hydrogen or LNG boil-off gas as fuel, and regardless of whether the ship uses LNG liquid as fuel, LNG liquid can be directly extracted to reduce the evaporation rate of the liquid hydrogen tank), the LNG pump 17 can pump out LNG liquid. After the LNG liquid passes through the LNG liquid main valve 20, it can pass through the LNG lower cooling coil inlet control valve 21 and the LNG upper cooling coil inlet control valve 22 respectively, and enter the upper cooling coil 4 and the lower cooling coil 5, thereby achieving cooling of the liquid hydrogen tank.

[0050] Reference Figure 1 In order to reduce the risk of overpressure, an LNG reflux pressure relief valve 27 connected to the cooling coil outlet control valve 26 is provided. The LNG reflux pressure relief valve 27 is used to actively relieve the overpressure risk caused by the cooling and gasification of LNG liquid, and can also be fully opened to directly reflux LNG liquid. The LNG evaporated gas or LNG liquid refluxed through the LNG reflux pressure relief valve 27 flows back into the LNG tank after passing through the LNG reflux valve 19.

[0051] Reference Figure 1 The device also includes a heating device 12, a compressor 13 and a gas supply valve 14. The heating device 12 is used to heat the evaporated gas at the outlet of the cooling coil to a normal temperature state, so that it can be used as a fuel by subsequent hydrogen or natural gas users. Furthermore, the compressor 13 is used to pressurize the normal temperature hydrogen or natural gas or a mixture of the two for use by hydrogen or natural gas or a mixture of the two users; the gas supply valve 14 is used to supply the normal temperature hydrogen or natural gas or a mixture of the two users without pressurization.

[0052] The operating principle of the device for reducing the evaporation rate of the ship's liquid hydrogen tank in this embodiment is:

[0053] The ship uses hydrogen or LNG as fuel. Regardless of the fuel used, this device will give priority to using the cold energy of the fuel to reduce the evaporation rate of the liquid hydrogen tank; even when the ship does not use hydrogen or natural gas as fuel, LNG can be directly extracted to cool the outer wall of the liquid hydrogen tank, and the cooled LNG and its evaporated gas can be returned to the LNG fuel tank, thereby actively reducing the evaporation rate of the liquid hydrogen tank.

[0054] When hydrogen is used as ship fuel, open the control valves 7 and 8 corresponding to the hydrogen boil-off gas to the cooling coils 4 and 5. Open the lower cooling coil inlet and outlet control valve 7 first to ensure that the lower outer wall of the liquid hydrogen tank is cooled first; if the outlet temperature of the lower cooling coil is low, open the upper cooling coil inlet and outlet control valve 8 to further cool the upper outer wall of the liquid hydrogen tank; when the hydrogen boil-off gas has sufficient cooling energy, open the hydrogen boil-off gas main pipeline control valve 9 to directly use the hydrogen boil-off gas as fuel.

[0055] When LNG is used as ship fuel, open the LNG liquid phase main valve 20 and the control valves 21 and 22 corresponding to the LNG to cooling coils 4 and 5. Open the lower cooling coil inlet and outlet control valve 21 first to ensure that the lower outer wall of the liquid hydrogen tank is cooled first; if the outlet temperature of the lower cooling coil is low, open the upper cooling coil inlet and outlet control valve 22 to further cool the upper outer wall of the liquid hydrogen tank; when the LNG cold energy is sufficient, open the LNG boil-off gas main pipeline control valve 23 to directly use the LNG boil-off gas as fuel.

[0056] When using LNG fuel tank boil-off gas as ship fuel, open the LNG boil-off gas main valve 18 and the control valves 21 and 22 corresponding to the boil-off gas to the cooling coils 4 and 5. Open the lower cooling coil inlet and outlet control valve 21 first to ensure that the lower outer wall of the liquid hydrogen tank is cooled first; if the outlet temperature of the lower cooling coil is low, open the upper cooling coil inlet and outlet control valve 22 to further cool the upper outer wall of the liquid hydrogen tank; when the LNG boil-off gas cooling energy is sufficient, open the main pipeline control valve to directly use the LNG boil-off gas as fuel. When there is no LNG fuel user, open the LNG reflux valve 19 to return the cooled LNG and its boil-off gas to the LNG fuel tank, thereby actively reducing the evaporation rate of the liquid hydrogen tank.

[0057] The compressor automatically adapts to the above three working conditions. It can extract hydrogen boil-off gas, LNG boil-off gas, boil-off gas generated after LNG cools the liquid hydrogen tank, and mix hydrogen and LNG boil-off gas in a certain proportion to extract the mixed gas.

[0058] For some users who can use low-pressure hydrogen or natural gas as fuel, such as boilers, gas combustion devices, fuel cells, etc., they can directly provide hydrogen, natural gas or a mixture of the two as fuel through the gas supply valve without using a compressor to increase the pressure.

[0059] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make modifications to the present embodiment without any creative contribution as needed. However, as long as it is within the scope of the claims of the present application, it shall be protected by the patent law.

Claims

1. A device for reducing the evaporation rate of a liquid hydrogen tank of a ship, the device is arranged based on the liquid hydrogen tank and LNG tank of a liquid hydrogen transport ship, characterized in that: It includes two or more groups of cooling coils arranged outside the liquid hydrogen tank, the inlet of the cooling coils is connected to the liquid hydrogen tank and the LNG tank, and the outlet of the cooling coils is connected to the LNG tank and the outside of the device; The device is provided with three cooling passages for cooling the liquid hydrogen cabin, including: Cooling path 1: Hydrogen evaporated gas enters the cooling coil from the liquid hydrogen tank to cool the liquid hydrogen tank, and then flows out of the device from the outlet of the cooling coil; Cooling path 2: LNG evaporated gas enters the cooling coil from the LNG tank to cool the liquid hydrogen tank, and then flows out of the device from the outlet of the cooling coil or flows back into the LNG tank; Cooling path three: LNG liquid enters the cooling coil from the LNG tank to cool the liquid hydrogen tank, and then flows out of the device from the cooling coil outlet or flows back to the LNG tank.

2. The device according to claim 1, characterized in that The liquid hydrogen tank comprises an inner wall and an outer wall of the liquid hydrogen tank. The outer wall of the liquid hydrogen tank is made of a low-temperature resistant metal material with good heat conduction effect. The interlayer between the inner wall and the outer wall of the liquid hydrogen tank is in a vacuum insulation form. An insulating coating material is arranged on the outer side of the outer wall of the liquid hydrogen tank.

3. The device according to claim 2, characterized in that The cooling coil is arranged close to the outer wall of the liquid hydrogen cabin, and the cooling coil includes an upper cooling coil and a lower cooling coil, and the upper cooling coil and the lower cooling coil are arranged at the upper part and the lower part of the liquid hydrogen cabin respectively.

4. The device according to claim 3, characterized in that A plurality of control valves for hydrogen boil-off gas are provided at the inlet of the cooling coil, including a hydrogen lower cooling coil inlet control valve, a hydrogen upper cooling coil inlet control valve and a hydrogen boil-off gas main valve connected to the liquid hydrogen tank, which are used to control the opening and closing of the hydrogen boil-off gas supply to control the working process of the cooling passage one.

5. The device according to claim 3, characterized in that The LNG tank includes an inner wall of the LNG tank and an insulation layer of the LNG tank. A plurality of control valves for LNG are also provided at the inlet of the cooling coil, including an LNG lower cooling coil inlet control valve, an LNG upper cooling coil inlet control valve and an LNG evaporated gas main valve provided at the inlet of the cooling coil, which are used to control the opening and closing of the LNG evaporated gas supply to control the working process of the cooling passage two.

6. The device according to claim 3, characterized in that The LNG tank includes an LNG tank inner wall and an LNG tank insulation layer. A plurality of control valves for LNG are also provided at the inlet of the cooling coil, including an LNG lower cooling coil inlet control valve, an LNG upper cooling coil inlet control valve and an LNG liquid main valve provided at the inlet of the cooling coil, which are used to control the opening and closing of the LNG liquid supply to control the working process of the cooling passage three.

7. The device according to claim 4, 5 or 6, characterized in that: A temperature sensor is provided at the outlet of the cooling coil to monitor the temperature state of the cooling coil outlet and adjust the control valve group according to the temperature change. A cooling coil outlet control valve is also provided at the outlet of the cooling coil.

8. The device according to claim 7, characterized in that An LNG reflux pressure relief valve is also provided on the passage connecting the cooling coil outlet and the LNG tank, which is used to open or close the reflux passage of LNG liquid or LNG evaporated gas.

9. The device according to claim 1, characterized in that The device also includes a heating device, a compressor and an air supply valve; the heating device, the compressor and the air supply valve are all arranged on a passage connecting the outlet of the cooling coil and the outside of the device; the heating device is used to heat the evaporated gas at the outlet of the cooling coil to a normal temperature state, so as to facilitate subsequent use as fuel by hydrogen or natural gas users; the compressor is used to pressurize normal temperature hydrogen or natural gas or a mixture of the two for use by hydrogen or natural gas users; the air supply valve is used to supply normal temperature hydrogen or natural gas or a mixture of the two without pressurization for use by hydrogen or natural gas users.

10. The working method of the device according to any one of claims 1 to 9, characterized in that: There are three working states: Working state 1: When the ship uses hydrogen as ship fuel, the hydrogen boil-off gas is used to reduce the evaporation rate of the liquid hydrogen tank. After the hydrogen boil-off gas passes through the hydrogen boil-off gas main valve, it passes through the hydrogen lower cooling coil inlet control valve and the hydrogen upper cooling coil inlet control valve respectively, and enters the upper cooling coil and the lower cooling coil, thereby realizing the cooling of the liquid hydrogen tank; Working state 2: When the ship uses LNG boil-off gas as ship fuel, the LNG boil-off gas is used to reduce the evaporation rate of the liquid hydrogen tank. After passing through the LNG boil-off gas main valve, the LNG boil-off gas passes through the LNG lower cooling coil inlet control valve and the LNG upper cooling coil inlet control valve respectively, and enters the upper cooling coil and the lower cooling coil, thereby realizing cooling of the liquid hydrogen tank; Working state three: When the ship does not use hydrogen or LNG boil-off gas as fuel, and regardless of whether the ship uses LNG liquid as fuel, LNG liquid can be directly extracted to reduce the evaporation rate of the liquid hydrogen tank. An LNG pump is installed in the LNG tank to pump out LNG liquid. After the LNG liquid passes through the LNG liquid main valve, it passes through the LNG lower cooling coil inlet control valve and the LNG upper cooling coil inlet control valve respectively, and then enters the upper cooling coil and the lower cooling coil, thereby achieving cooling of the liquid hydrogen tank.

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