Actively adiabatic liquid hydrogen storage tank and insulation method for reverse Brayton helium refrigeration cycle

Abstract

This invention relates to a liquid hydrogen storage tank, specifically to an active insulation liquid hydrogen storage tank and insulation method using a reverse Brayton helium refrigeration cycle. It solves the technical problems of existing active insulation methods for liquid hydrogen storage tanks, which use cryogenic refrigerators, resulting in high energy consumption, low cooling capacity, low efficiency, and unsuitability for large liquid hydrogen storage tanks. The liquid hydrogen storage tank of this invention includes a storage tank unit, a reverse Brayton helium refrigeration cycle system, a draining system, a vacuum system, and a sensing device. The storage tank unit includes an outer liquid hydrogen tank, an inner liquid hydrogen tank, and an insulation jacket. The reverse Brayton helium refrigeration cycle system exchanges heat between cryogenic helium and liquid hydrogen within the storage tank, absorbing heat from the tank and extending the liquid hydrogen storage time. The draining system is used to discharge liquid hydrogen. The vacuum system is used to maintain the vacuum state of the insulation jacket. The sensing device is used to monitor the pressure and liquid hydrogen level within the inner tank. Simultaneously, this invention also provides the insulation method for the aforementioned liquid hydrogen storage tank.

Description

Technical Field

[0001] This invention relates to a liquid hydrogen storage tank, specifically to an active adiabatic liquid hydrogen storage tank and a method for insulating a reverse Brayton helium refrigeration cycle. Background Technology

[0002] Hydrogen energy has advantages such as being clean, efficient, and abundant in resources, and is widely used in aerospace, automotive and other fields. With the growth of energy demand and the transformation of energy systems to low-carbon based systems, renewable energy is receiving more and more attention. However, renewable energy has problems such as intermittency and limited conversion efficiency. Hydrogen, as an energy carrier, can realize the storage of renewable energy.

[0003] Commonly used hydrogen storage methods include compressed gaseous hydrogen storage, cryogenic liquid hydrogen storage, solid hydrogen storage, and organic liquid hydrogen storage. Among them, cryogenic liquid hydrogen storage is the preferred hydrogen storage method for ground transportation and mobile applications due to its advantages such as high energy density, good safety, and short hydrogen refueling time.

[0004] Due to the significant temperature difference between liquid hydrogen and the external environment, heat leakage and evaporation losses are inevitable. Furthermore, because hydrogen has an extremely low boiling point and low heat of vaporization, liquid hydrogen storage tanks require effective insulation to minimize evaporation losses. Insulation methods for liquid hydrogen storage tanks can be categorized into active and passive insulation. Among passive insulation methods, high-vacuum multilayer insulation, vacuum hollow glass microsphere insulation, and vacuum perlite insulation offer relatively good insulation performance. Active insulation primarily relies on a refrigeration unit to actively provide cooling capacity for heat transfer.

[0005] Compared with passive insulation, active insulation is more widely used in liquid hydrogen storage tanks. However, existing 20K temperature zone cryogenic refrigerators have problems such as high energy consumption and small cooling capacity, resulting in low efficiency, and are not suitable for large liquid hydrogen storage tanks. Summary of the Invention

[0006] The purpose of this invention is to solve the technical problems of existing active insulation methods for liquid hydrogen storage tanks, which use cryogenic refrigerators, resulting in high energy consumption and low cooling capacity, leading to low efficiency and unsuitability for large liquid hydrogen storage tanks. The invention provides an active insulation liquid hydrogen storage tank and insulation method based on a reverse Brayton helium refrigeration cycle.

[0007] The technical solution of this invention is:

[0008] The present invention provides an active adiabatic liquid hydrogen storage tank with a reverse Brayton helium refrigeration cycle, which is characterized by including a storage tank unit, a reverse Brayton helium refrigeration cycle system, a draining system, a vacuum system, and a sensing device.

[0009] The storage tank unit includes an outer tank for liquid hydrogen storage, an inner tank for liquid hydrogen storage located inside the outer tank, and an insulation interlayer located between the inner tank and the outer tank.

[0010] The reverse Brayton helium refrigeration cycle system includes a helium source, a compressor, a first-stage heat exchanger, a liquid nitrogen tank, a second-stage heat exchanger, an expander, and two heat exchange pipes connected by insulated pipes.

[0011] The heat exchange pipe has a ring structure and is laid horizontally inside the liquid hydrogen storage tank with its outer wall close to the inner wall of the liquid hydrogen storage tank. Two heat exchange pipes are laid vertically and are connected to each other. The upper heat exchange pipe is located close to the liquid surface of the liquid hydrogen, and the lower heat exchange pipe is located at the equator of the liquid hydrogen storage tank.

[0012] Helium from the helium source enters the compressor for compression. The compressed helium is cooled sequentially through the first-stage heat exchanger, the liquid nitrogen tank, and the second-stage heat exchanger. It then enters the expander to expand and lower the temperature to below 20K. It then exchanges heat with the liquid hydrogen in the liquid hydrogen storage tank through the upper and lower heat exchange pipes. The helium that has been heated by the heat exchange is output from the outlet of the lower heat exchange pipe. It then passes through the second-stage heat exchanger and the first-stage heat exchanger to be reheated before returning to the compressor to enter the cycle.

[0013] The drainage system is connected to the inner tank of the liquid hydrogen storage tank via a pipeline and is used for the drainage of liquid hydrogen from the inner tank of the liquid hydrogen storage tank.

[0014] The vacuum system is connected to the insulation interlayer and is used to maintain the vacuum state of the insulation interlayer.

[0015] The sensing device is used to monitor the pressure inside the liquid hydrogen storage tank and the liquid hydrogen level.

[0016] Furthermore, the inner tank of the liquid hydrogen storage tank is provided with a first drain hole at the bottom and a first return vent at the top; the outer tank of the liquid hydrogen storage tank and the insulation jacket are respectively provided with second drain holes corresponding to the first drain holes at their bottoms, and the outer tank of the liquid hydrogen storage tank and the insulation jacket are respectively provided with second return vents corresponding to the first return vents at their tops; the draining system includes a drain pipe, a drain valve, a self-pressurizing valve, a self-pressurizer, and a pressurizing return vent valve; the drain end of the drain pipe is connected to the interior of the inner tank of the liquid hydrogen storage tank through the first drain hole and the two second drain holes, and the return vent of the drain pipe is connected to the interior of the inner tank through the first drain hole and the two second drain holes. The first return vent and two second return vents are connected to the interior of the inner tank of the liquid hydrogen storage tank. The drain valve, self-pressurizing valve, self-pressurizer, and pressurized return vent valve are sequentially arranged along the drain pipeline from the drain end to the return vent end. The drain valve, self-pressurizing valve, and self-pressurizer are located near the bottom of the inner tank of the liquid hydrogen storage tank, and the pressurized return vent valve is located near the top of the inner tank of the liquid hydrogen storage tank. A branch pipeline is provided between the drain valve and the self-pressurizing valve to transport the discharged liquid hydrogen into a liquid hydrogen tanker. The self-pressurizing valve, self-pressurizer, and pressurized return vent valve are used to vaporize the passing liquid hydrogen and return it to the inner tank of the liquid hydrogen storage tank.

[0017] Furthermore, the vacuum system includes a vacuum pump, a vacuum valve, a vacuum gauge tube, and a vacuum meter; the vacuum pump is connected to the interior of the insulation jacket; the vacuum valve is installed on the pipeline between the vacuum pump and the insulation jacket to control the vacuum level of the insulation jacket; the vacuum gauge tube is matched with the vacuum meter to measure the vacuum level of the insulation jacket.

[0018] Further, the sensing device includes a gas phase pressure tapping line, a liquid phase pressure tapping line, a pressure gauge, a pressure gauge valve, a differential pressure level gauge, an upper valve of the level gauge, a lower valve of the level gauge, and a balancing valve; one end of the gas phase pressure tapping line is connected to the top of the inner tank of the liquid hydrogen storage tank and communicates with the inside of the inner tank; the other end of the gas phase pressure tapping line extends to the bottom of the inner tank of the liquid hydrogen storage tank and is provided with two branches; one end of the liquid phase pressure tapping line is connected to the bottom of the inner tank of the liquid hydrogen storage tank and communicates with the inside of the inner tank; the liquid phase pressure tapping line... The other end has two branches; the two branches of the gas phase pressure tapping pipeline and the two branches of the liquid phase pressure tapping pipeline are connected by a differential pressure level gauge and a balancing valve, respectively; the pressure gauge, pressure gauge valve, and upper valve of the level gauge are installed on the gas phase pressure tapping pipeline, and the pressure gauge and pressure gauge valve are installed near the top of the inner tank of the liquid hydrogen storage tank to measure the pressure in the gas pillow area of ​​the liquid hydrogen storage tank, and the upper valve of the level gauge is installed near the bottom of the inner tank of the liquid hydrogen storage tank; the lower valve of the level gauge is installed on the liquid phase pressure tapping pipeline and is located near the bottom of the inner tank of the liquid hydrogen storage tank.

[0019] Furthermore, the outer tank and the inner tank of the liquid hydrogen storage tank are connected by a suspended support structure.

[0020] Furthermore, the insulating interlayer is made of any one of the following: multilayer insulating materials, hollow glass microspheres, and perlite.

[0021] Furthermore, the total thickness of the multi-layer insulation material is 10cm; the insulation pipe is wrapped with multi-layer insulation material.

[0022] Meanwhile, the present invention also provides an insulation method for the above-mentioned active adiabatic liquid hydrogen storage tank with a reverse Brayton helium refrigeration cycle, which is characterized by including the following steps:

[0023] 1) Perform liquid hydrogen filling, while simultaneously activating the vacuum system to maintain the vacuum state of the insulation jacket, and monitor the liquid hydrogen level in the liquid hydrogen storage tank through the sensor device. Stop liquid hydrogen filling when the liquid hydrogen level reaches 90%.

[0024] 2) The pressure inside the liquid hydrogen storage tank is detected by a sensor. When the pressure reaches the set value, the reverse Brayton helium refrigeration cycle system is activated for active insulation.

[0025] Further, in step 2), the active insulation method is as follows: the helium from the helium source enters the compressor for compression, and the compressed helium is cooled sequentially through the first-stage heat exchanger, the liquid nitrogen tank, and the second-stage heat exchanger. Then, it enters the expander to expand and lower the temperature to below 20K. It then exchanges heat with the liquid hydrogen in the liquid hydrogen storage tank through the upper and lower heat exchange pipes. The helium that has been heated by the heat exchange is output from the outlet of the lower heat exchange pipe, and then returns to the compressor after being reheated by passing through the second-stage heat exchanger and the first-stage heat exchanger.

[0026] Further, in step 1), when monitoring the liquid hydrogen level, first open the balancing valve, then open the upper valve and the lower valve of the level gauge in sequence, and then close the balancing valve. The differential pressure level gauge then starts working.

[0027] The beneficial effects of this invention are:

[0028] 1. The present invention relates to an active adiabatic liquid hydrogen storage tank with a reverse Brayton helium refrigeration cycle. After the helium temperature is lowered to below 20K by the reverse Brayton helium refrigeration cycle, the cryogenic helium is introduced into the annular heat exchange pipe installed in the liquid hydrogen storage tank. Through heat exchange between the cryogenic helium and the liquid hydrogen in the liquid hydrogen storage tank, the heat in the tank is absorbed, extending the liquid hydrogen storage time. This solves the problems of high energy consumption, low cooling capacity and low efficiency of cryogenic refrigerators, and is suitable for the insulation of large cryogenic spherical tanks.

[0029] 2. In the active adiabatic liquid hydrogen storage tank of the reverse Brayton helium refrigeration cycle of the present invention, the heat exchange pipe inside the liquid hydrogen storage tank is divided into two parts, upper and lower. The upper heat exchange pipe is close to the liquid surface, and the lower heat exchange pipe is located at the equator of the inner tank of the liquid hydrogen storage tank. This can alleviate the local liquid hydrogen temperature rise and the phenomenon of heat stratification inside the tank caused by heat leakage at the support structure.

[0030] 3. The present invention provides an active adiabatic liquid hydrogen storage tank with a reverse Brayton helium refrigeration cycle. The drainage system is equipped with a self-pressurizing valve, a self-pressurizer, and a pressurizing return valve. Self-pressurization is achieved by vaporizing a portion of the liquid hydrogen. This ensures stable pressure inside the liquid hydrogen storage tank during drainage without the need for an external pressurizing device. Furthermore, the amount of vaporized liquid hydrogen can be controlled by adjusting the opening of the self-pressurizing valve, thereby further controlling the drainage pressure of the liquid hydrogen storage tank.

[0031] 4. The present invention provides an active insulation method for liquid hydrogen storage tanks with a reverse Brayton helium refrigeration cycle. The insulation interlayer uses a multi-layer insulation material with a thickness of 10cm and 160 layers. Theoretical calculations show that this configuration can isolate most of the environmental heat leakage. If the thickness or number of insulation layers is further increased, the heat leakage will decrease only slightly, but the cost will continue to increase. Therefore, this configuration can well balance insulation performance and economy. Attached Figure Description

[0032] Figure 1This is a schematic diagram of the structure of an active adiabatic liquid hydrogen storage tank according to an embodiment of the reverse Brayton helium refrigeration cycle of the present invention.

[0033] Explanation of reference numerals in the attached diagram: 1-Inner tank of liquid hydrogen storage; 2-Outer tank of liquid hydrogen storage; 3-Insulation jacket; 4-Reverse Brayton helium refrigeration cycle system; 41-Compressor; 42-First stage heat exchanger; 43-Liquid nitrogen tank; 44-Second stage heat exchanger; 45-Expander; 46-Heat exchange pipeline; 5-Drainage system; 51-Drainage valve; 52-Self-pressurizing valve; 53-Self-pressurizing unit; 54-Pressure booster return valve; 6-Vacuum system; 61-Vacuum valve; 62-Vacuum gauge pipe; 7-Sensing device; 71-Pressure gauge; 72-Pressure gauge valve; 73-Differential pressure level gauge; 74-Upper valve of level gauge; 75-Lower valve of level gauge; 76-Balancing valve; 77-Gas phase pressure tapping pipeline; 78-Liquid phase pressure tapping pipeline; 8-Suspended support structure. Detailed Implementation

[0034] The present invention will now be described in detail with reference to embodiments and accompanying drawings.

[0035] This invention discloses an actively adiabatic liquid hydrogen storage tank with a reverse Brayton helium refrigeration cycle, such as... Figure 1 As shown, the system includes a storage tank unit, a reverse Brayton helium refrigeration cycle system 4, a draining system 5, a vacuum system 6, and a sensing device 7. The draining system 5 is connected to the inner tank 1 of the liquid hydrogen storage tank via a pipeline and is used to drain liquid hydrogen from the inner tank 1. The vacuum system 6 is connected to the insulation jacket 3 and is used to maintain the vacuum state of the insulation jacket 3. The sensing device 7 is used to monitor the pressure and liquid hydrogen level inside the inner tank 1 of the liquid hydrogen storage tank.

[0036] The storage tank unit includes an outer liquid hydrogen storage tank 2, an inner liquid hydrogen storage tank 1 disposed within the outer liquid hydrogen storage tank 2, and an insulating interlayer 3 disposed between the inner liquid hydrogen storage tank 1 and the outer liquid hydrogen storage tank 2. The outer liquid hydrogen storage tank 2 and the inner liquid hydrogen storage tank 1 are connected by a suspended support structure 8. The bottom of the inner liquid hydrogen storage tank 1 is provided with a first drain hole, and the top is provided with a first vent hole; the bottoms of the outer liquid hydrogen storage tank 2 and the insulating interlayer 3 are respectively provided with second drain holes corresponding to the first drain holes, and the tops of the outer liquid hydrogen storage tank 2 and the insulating interlayer 3 are respectively provided with second vent holes corresponding to the first vent holes. The insulating interlayer 3 needs to be vacuumed and filled with any one of the following: multi-layer insulation material, hollow glass microspheres, and perlite for insulation. Because multi-layer insulation has better insulation performance, this embodiment uses multi-layer insulation for filling, with a total thickness of 10 cm and a total of 160 layers.

[0037] The reverse Brayton helium refrigeration cycle system 4 includes a helium source, a compressor 41, a first-stage heat exchanger 42, a liquid nitrogen tank 43, a second-stage heat exchanger 44, an expander 45, and two heat exchange pipes 46 connected by insulated pipes. The heat exchange pipe 46 has a ring structure. Due to heat leakage at the tank wall of the inner tank 1 of the hydrogen storage tank, the liquid hydrogen temperature near the wall is relatively high. The higher-temperature liquid hydrogen rises along the wall, causing the upper layer of liquid hydrogen to be hotter than the lower layer, resulting in thermal stratification. At the same time, the suspended support structure at the equator of the inner tank 1 of the hydrogen storage tank has significant heat leakage, resulting in a high temperature in that area. Therefore, the heat exchange pipe 46 is laid horizontally inside the inner tank 1 of the liquid hydrogen storage tank, with its outer wall close to the inner wall of the inner tank 1. Two heat exchange pipes 46 are installed, laid vertically and interconnected. The upper heat exchange pipe 46 is positioned close to the liquid hydrogen surface, generally at 90% of the liquid level, to alleviate thermal stratification. The lower heat exchange pipe 46 is located at the equator of the inner tank 1 of the liquid hydrogen storage tank to reduce the liquid hydrogen temperature in that area. The insulated pipes are wrapped with multiple layers of insulation material to prevent external heat from raising the helium temperature through the pipes.

[0038] The working principle of the reverse Brayton helium refrigeration cycle system 4 is as follows: Helium from the helium source enters the compressor 41 for compression. The compressed helium is cooled sequentially through the first-stage heat exchanger 42, the liquid nitrogen tank 43, and the second-stage heat exchanger 44. Then, it enters the expander 45 to expand and lower the temperature to below 20K. It then exchanges heat with the liquid hydrogen in the inner tank 1 of the liquid hydrogen storage tank through the upper heat exchange pipe 46. The helium that has been heated by the heat exchange is output from the lower heat exchange pipe 46. After being reheated by passing through the second-stage heat exchanger 44 and the first-stage heat exchanger 42, it returns to the compressor 41 to enter the cycle.

[0039] The drainage system 5 includes a drainage pipeline, a drainage valve 51, a self-pressurizing valve 52, a self-pressurizer 53, and a pressurized return valve 54. The drainage pipeline's drainage end connects to the interior of the inner tank 1 of the liquid hydrogen storage tank via a first drainage hole and two second drainage holes. The return end of the drainage pipeline also connects to the interior of the inner tank 1 via a first return hole and two second return holes. Along the drainage pipeline from the drainage end to the return end, the drainage pipeline is sequentially equipped with the drainage valve 51, the self-pressurizing valve 52, the self-pressurizer 53, and the pressurized return valve 54. The drainage valve 51, the self-pressurizing valve 52, and the self-pressurizer 53 are located near the bottom of the inner tank 1 of the liquid hydrogen storage tank, while the pressurized return valve 54 is located near the top of the inner tank 1. A branch pipeline is provided between the drainage valve 51 and the self-pressurizing valve 52 for transporting the drained liquid hydrogen into a liquid hydrogen tanker. The self-pressurizing valve 52, self-pressurizer 53, and pressurized return valve 54 are used to vaporize the passing liquid hydrogen before returning it to the inner tank 1 of the liquid hydrogen storage tank, thereby maintaining the pressure stability of the inner tank 1. During use, after the drain valve 51 is opened, the self-pressurizing valve 52, self-pressurizer 53, and pressurized return valve 54 are opened simultaneously. By adjusting the opening of the self-pressurizing valve 52, some of the liquid hydrogen discharged from the liquid hydrogen storage tank enters the self-pressurizer 53 for vaporization. The vaporized hydrogen gas is then introduced from the top of the liquid hydrogen storage tank into the air cushion area of ​​the inner tank through the pressurized return valve 54, in order to maintain sufficient and stable pressure in the inner tank during draining.

[0040] The vacuum system 6 includes a vacuum pump, a vacuum valve 61, a vacuum gauge tube 62, and a vacuum gauge. The vacuum pump is internally connected to the insulation jacket 3. The vacuum valve 61 is installed on the pipeline between the vacuum pump and the insulation jacket 3 to control the vacuum level of the insulation jacket 3. The vacuum gauge tube 62 is matched with the vacuum gauge to measure the vacuum level of the insulation jacket 3, so as to ensure that the insulation jacket 3 always maintains a high vacuum state and reduces gas heat conduction.

[0041] The sensing devices 7 consist of a pressure sensor and a level sensor. The pressure sensor monitors the pressure inside the liquid hydrogen storage tank and activates the reverse Brayton helium refrigeration cycle system when the pressure exceeds the set pressure. The level sensor monitors the liquid hydrogen level during the liquid hydrogen filling process or discharge into the tank truck. The sensing devices 7 include a gas phase pressure tapping line 77, a liquid phase pressure tapping line 78, a pressure gauge 71, a pressure gauge valve 72, a differential pressure level gauge 73, an upper valve 74 for the level gauge, a lower valve 75 for the level gauge, and a balancing valve 76. One end of the gas phase pressure tapping line 77 connects to the top of the inner tank 1 of the liquid hydrogen storage tank and communicates with the interior of the inner tank 1; the other end of the gas phase pressure tapping line 77 extends to the bottom of the inner tank 1 and has two branches. One end of the liquid phase pressure tapping line 78 connects to the bottom of the inner tank 1 of the liquid hydrogen storage tank and communicates with the interior of the inner tank 1; the other end of the liquid phase pressure tapping line 78 has two branches. Two branches of the gas phase pressure tapping line 77 and two branches of the liquid phase pressure tapping line 78 are connected via a differential pressure level gauge 73 and a balancing valve 76, respectively. Pressure gauge 71, pressure gauge valve 72, and upper valve 74 of the level gauge are installed on the gas phase pressure tapping line 77, with pressure gauge 71 and pressure gauge valve 72 positioned near the top of the inner tank 1 of the liquid hydrogen storage tank to measure the pressure in the gas cushion area of ​​the liquid hydrogen storage tank. Upper valve 74 of the level gauge is positioned near the bottom of the inner tank 1 of the liquid hydrogen storage tank. Lower valve 75 of the level gauge is installed on the liquid phase pressure tapping line 78, also near the bottom of the inner tank 1 of the liquid hydrogen storage tank.

[0042] The working principle of the active adiabatic liquid hydrogen storage tank of the reverse Brayton helium refrigeration cycle of the present invention is as follows: During the use of the above-mentioned liquid hydrogen storage tank, the ambient heat is transferred to the wall of the container 1 inside the liquid hydrogen storage tank, causing the temperature of the liquid hydrogen near the wall to rise. The density of the liquid hydrogen decreases as the temperature rises, and it rises along the tank wall, making the temperature of the upper layer of liquid hydrogen in the tank higher than that of the lower layer, resulting in thermal stratification. At this time, the reverse Brayton helium refrigeration cycle system 4 is activated. The compressed helium gas is cooled by the first-stage heat exchanger 42, the liquid nitrogen tank 43 and the second-stage heat exchanger 44, and then expands in the expander 45 to lower the temperature to below 20K. Then, it exchanges heat with the liquid hydrogen in the tank through the heat exchange pipe 46. The helium gas, which has been heated by heat exchange, is reheated by the second-stage heat exchanger 44 and the first-stage heat exchanger 42 and then returns to the helium compressor 41 to enter the cycle. When liquid hydrogen needs to be discharged from the liquid hydrogen storage tank to the liquid hydrogen tank truck, the discharge valve 51 is opened, and the opening of the self-pressurizing valve 52 is controlled simultaneously. This allows some of the liquid hydrogen to vaporize in the self-pressurizer 53 and then return to the top of the inner tank 1 via the pressurization return valve 54 for pressurization, thus maintaining sufficient and stable pressure in the inner tank 1 during discharge. The insulation jacket 3 needs to be kept under vacuum. The vacuum system 6 is connected to the insulation jacket 3. After connecting the vacuum valve 61 to the vacuum pump, the insulation jacket 3 can be evacuated. The vacuum gauge tube 62, paired with a vacuum meter, can measure the vacuum level.

[0043] The present invention also provides an insulation method for an actively adiabatic liquid hydrogen storage tank with the above-mentioned reverse Brayton helium refrigeration cycle, comprising the following steps:

[0044] 1) Perform liquid hydrogen filling, while simultaneously activating the vacuum system 6 to maintain the vacuum state of the insulation jacket 3, and monitoring the liquid hydrogen level in the inner tank 1 of the liquid hydrogen storage tank through the sensor device 7. Stop liquid hydrogen filling when the liquid hydrogen level reaches 90%.

[0045] When monitoring the liquid hydrogen level, first open the balance valve 76, then open the upper valve 74 and the lower valve 75 of the level gauge in sequence, and then close the balance valve 76. The differential pressure level gauge 73 will then start working.

[0046] 2) The pressure inside the liquid hydrogen storage tank 1 is detected by the sensor device 7. When the pressure reaches the set value, the reverse Brayton helium refrigeration cycle system 4 is turned on to perform active insulation.

[0047] After the liquid hydrogen storage tank is filled, the tank is insulated by multiple layers of insulation material in the vacuum insulation jacket. This insulation method can isolate a large amount of external heat leakage, but it still cannot completely avoid heat leakage at the tank wall. In addition, the suspended support structure that connects the outer and inner tanks of the liquid hydrogen spherical tank also has heat leakage. Therefore, the liquid hydrogen in the tank will evaporate due to heat leakage, which will cause the pressure inside the liquid hydrogen storage tank to rise. The pressure in the gas pillow area of ​​the liquid hydrogen storage tank is monitored by a pressure gauge. When the pressure reaches the set value, the reverse Brayton helium refrigeration cycle system is activated for active insulation. Low temperature helium is introduced into the annular heat exchange pipe to exchange heat with the higher temperature liquid hydrogen in the liquid hydrogen storage tank and then re-enters the refrigeration cycle to remove the heat from the liquid hydrogen storage tank.

[0048] The active insulation method is as follows: Helium from the helium source enters the compressor 41 for compression. The compressed helium is cooled sequentially through the first-stage heat exchanger 42, the liquid nitrogen tank 43, and the second-stage heat exchanger 44. Then, it enters the expander 45 for expansion, reducing the temperature to below 20K. It then exchanges heat with the liquid hydrogen in the inner tank 1 of the liquid hydrogen storage tank through the upper and lower heat exchange pipes 46. The helium that has been heated by the heat exchange is output from the outlet of the lower heat exchange pipe 46. After being reheated by passing through the second-stage heat exchanger 44 and the first-stage heat exchanger 42, it returns to the compressor 41 to enter the cycle.

[0049] When it is necessary to discharge the liquid hydrogen in the inner tank 1 of the liquid hydrogen storage tank to the liquid hydrogen tank truck, the discharge valve 51 is opened, and the opening of the self-pressurizing valve 52 is controlled at the same time. This allows some of the liquid hydrogen to be vaporized in the self-pressurizer 53 and then returned to the top of the inner tank 1 of the liquid hydrogen storage tank via the pressurizing return valve 54 for pressurization, so as to maintain sufficient and stable pressure in the inner tank 1 of the liquid hydrogen storage tank during discharge.

Claims

1. An actively adiabatic liquid hydrogen storage tank with a reverse Brayton helium refrigeration cycle, characterized in that: It includes a storage tank unit, a reverse Brayton helium refrigeration cycle system (4), a drain system (5), a vacuum system (6), and a sensing device (7). The storage tank unit includes an outer tank (2) of liquid hydrogen storage tank, an inner tank (1) of liquid hydrogen storage tank disposed inside the outer tank (2) of liquid hydrogen storage tank, and an insulation interlayer (3) disposed between the inner tank (1) of liquid hydrogen storage tank and the outer tank (2) of liquid hydrogen storage tank. The reverse Brayton helium refrigeration cycle system (4) includes a helium source, a compressor (41), a first-stage heat exchanger (42), a liquid nitrogen tank (43), a second-stage heat exchanger (44), an expander (45), and two heat exchange pipes (46) connected by an insulated pipe. The heat exchange pipe (46) is a ring structure. The heat exchange pipe (46) is laid horizontally inside the inner tank (1) of the liquid hydrogen storage tank and the outer wall of the pipe is close to the inner wall of the inner tank (1) of the liquid hydrogen storage tank. The two heat exchange pipes (46) are laid vertically and connected to each other. The upper heat exchange pipe (46) is set close to the liquid surface of the liquid hydrogen, and the lower heat exchange pipe (46) is located at the equator of the inner tank (1) of the liquid hydrogen storage tank. Helium from the helium source enters the compressor (41) for compression. The compressed helium passes through the first-stage heat exchanger (42), the liquid nitrogen tank (43), and the second-stage heat exchanger (44) for cooling. It then enters the expander (45) for expansion, reducing the temperature to below 20K. It then exchanges heat with the liquid hydrogen in the inner tank (1) of the liquid hydrogen storage tank through the upper heat exchange pipe (46) and the lower heat exchange pipe (46). The helium heated by the heat exchange is output from the outlet of the lower heat exchange pipe (46). It then passes through the second-stage heat exchanger (44) and the first-stage heat exchanger (42) for reheating before returning to the compressor (41) to enter the cycle. The drainage system (5) is connected to the inner tank (1) of the liquid hydrogen storage tank via a pipeline, and is used for the discharge of liquid hydrogen from the inner tank (1), specifically: The bottom of the inner tank (1) of the liquid hydrogen storage tank is provided with a first drain hole and the top is provided with a first return gas hole; the bottom of the outer tank (2) of the liquid hydrogen storage tank and the insulation jacket (3) are respectively provided with a second drain hole corresponding to the first drain hole, and the top of the outer tank (2) of the liquid hydrogen storage tank and the insulation jacket (3) are respectively provided with a second return gas hole corresponding to the first return gas hole. The drainage system (5) includes a drainage pipeline, a drainage valve (51), a self-pressurizing valve (52), a self-pressurizer (53), and a pressurizing return valve (54). The drain end of the drain pipe is connected to the interior of the inner tank (1) of the liquid hydrogen storage tank through the first drain hole and two second drain holes, and the return end of the drain pipe is connected to the interior of the inner tank (1) of the liquid hydrogen storage tank through the first return hole and two second return holes. The drain valve (51), self-pressurizing valve (52), self-pressurizer (53) and pressurizing return valve (54) are arranged sequentially from the drain end to the return end of the drain pipeline. The drain valve (51), self-pressurizing valve (52) and self-pressurizer (53) are located near the bottom of the inner tank (1) of the liquid hydrogen storage tank, and the pressurizing return valve (54) is located near the top of the inner tank (1) of the liquid hydrogen storage tank. A branch pipeline is provided between the drain valve (51) and the self-pressurizing valve (52) to transport the drained liquid hydrogen into the liquid hydrogen tanker. The self-pressurizing valve (52), the self-pressurizer (53), and the pressurizing return valve (54) are used to vaporize the passing liquid hydrogen and return it to the inner tank (1) of the liquid hydrogen storage tank. The vacuum system (6) is connected to the insulation interlayer (3) to maintain the vacuum state of the insulation interlayer (3); The sensing device (7) is used to monitor the pressure and liquid hydrogen level inside the inner tank (1) of the liquid hydrogen storage tank.

2. The active adiabatic liquid hydrogen storage tank with a reverse Brayton helium refrigeration cycle according to claim 1, characterized in that: The vacuum system (6) includes a vacuum pump, a vacuum valve (61), a vacuum gauge tube (62), and a vacuum gauge. The vacuum pump is connected to the interior of the insulation jacket (3). The vacuum valve (61) is installed on the pipeline between the vacuum pump and the insulation jacket (3) to control the vacuum level of the insulation jacket (3). The vacuum gauge tube (62) is matched with the vacuum gauge and is used to measure the vacuum level of the insulation jacket (3).

3. The active adiabatic liquid hydrogen storage tank with a reverse Brayton helium refrigeration cycle according to claim 2, characterized in that: The sensing device (7) includes a gas phase pressure tapping line (77), a liquid phase pressure tapping line (78), a pressure gauge (71), a pressure gauge valve (72), a differential pressure level gauge (73), an upper valve of the level gauge (74), a lower valve of the level gauge (75), and a balancing valve (76). One end of the gas phase pressure tapping pipeline (77) is connected to the top of the inner tank (1) of the liquid hydrogen storage tank and communicates with the inside of the inner tank (1); the other end of the gas phase pressure tapping pipeline (77) extends to the bottom of the inner tank (1) of the liquid hydrogen storage tank and is provided with two branches. One end of the liquid phase pressure tapping pipeline (78) is connected to the bottom of the inner tank (1) of the liquid hydrogen storage tank and communicates with the inside of the inner tank (1); the other end of the liquid phase pressure tapping pipeline (78) is provided with two branches. The two branches of the gas phase pressure tapping line (77) and the two branches of the liquid phase pressure tapping line (78) are connected by a differential pressure level gauge (73) and a balancing valve (76), respectively. The pressure gauge (71), pressure gauge valve (72) and level gauge upper valve (74) are installed on the gas phase pressure tapping pipeline (77), and the pressure gauge (71) and pressure gauge valve (72) are installed near the top of the inner tank (1) of the liquid hydrogen storage tank to measure the pressure in the gas pillow area of ​​the liquid hydrogen storage tank, and the level gauge upper valve (74) is installed near the bottom of the inner tank (1) of the liquid hydrogen storage tank; The lower valve (75) of the level gauge is located on the liquid phase pressure line (78) and near the bottom of the inner tank (1) of the liquid hydrogen storage tank.

4. The active adiabatic liquid hydrogen storage tank with a reverse Brayton helium refrigeration cycle according to any one of claims 1-3, characterized in that: The outer tank (2) of the liquid hydrogen storage tank is connected to the inner tank (1) of the liquid hydrogen storage tank through a suspended support structure (8).

5. The active adiabatic liquid hydrogen storage tank with a reverse Brayton helium refrigeration cycle according to claim 4, characterized in that: The insulation interlayer (3) is made of any one of the following: multi-layer insulation material, hollow glass microspheres, and perlite.

6. The active adiabatic liquid hydrogen storage tank with a reverse Brayton helium refrigeration cycle according to claim 5, characterized in that: The total thickness of the multilayer thermal insulation material is 10 cm; The insulated pipe is wrapped with multiple layers of insulation material.

7. A method for insulating an actively insulating liquid hydrogen storage tank with a reverse Brayton helium refrigeration cycle as described in any one of claims 1-6, characterized in that, Includes the following steps: 1) Perform liquid hydrogen filling, and at the same time turn on the vacuum system (6) to maintain the vacuum state of the insulation jacket (3), and monitor the liquid hydrogen level in the inner tank (1) of the liquid hydrogen storage tank through the sensor device (7). Stop liquid hydrogen filling when the liquid hydrogen level reaches 90%. 2) The pressure inside the liquid hydrogen storage tank (1) is detected by the sensor (7). When the pressure reaches the set value, the reverse Brayton helium refrigeration cycle system (4) is turned on to perform active insulation.

8. The insulation method for an actively adiabatic liquid hydrogen storage tank with a reverse Brayton helium refrigeration cycle according to claim 7, characterized in that: In step 2), the active insulation method is as follows: the helium gas from the helium source enters the compressor (41) for compression, and the compressed helium gas is cooled sequentially through the first-stage heat exchanger (42), the liquid nitrogen tank (43), and the second-stage heat exchanger (44). Then, it enters the expander (45) to expand and lower the temperature to below 20K. Then, it exchanges heat with the liquid hydrogen in the inner tank (1) of the liquid hydrogen storage tank through the upper heat exchange pipe (46) and the lower heat exchange pipe (46). The helium gas heated by the heat exchange is output from the outlet of the lower heat exchange pipe (46), and then returns to the compressor (41) after being reheated by the second-stage heat exchanger (44) and the first-stage heat exchanger (42) in sequence to enter the cycle.

9. The insulation method for an actively adiabatic liquid hydrogen storage tank with a reverse Brayton helium refrigeration cycle according to claim 8, characterized in that: In step 1), when monitoring the liquid hydrogen level, first open the balance valve (76), then open the upper valve (74) and the lower valve (75) of the level gauge in sequence, and then close the balance valve (76). The differential pressure level gauge (73) then starts to work.

Images