Liquid hydrogen hydrogenation machine

Abstract

The utility model discloses a liquid hydrogen adding machine, which relates to the technical field of liquid hydrogen adding and comprises a filling pipeline assembly, a gas return pipeline assembly, a precooling pipeline assembly and a safety emptying pipeline assembly, and the filling pipeline assembly, the gas return pipeline assembly and the precooling pipeline assembly are all communicated with the safety emptying pipeline assembly. According to the scheme, through more scientific and reasonable circulating pre-cooling process design, full pre-cooling of a pipeline system and core components can be guaranteed in the large and small circulating pre-cooling process of the hydrogen liquid adding machine, and meanwhile the situation that the service life and the quality stability of the gas phase flowmeter are affected by scouring of a hydrogen low-temperature medium in the pre-cooling process is avoided; in addition, the BOG return port is separated from the liquid phase port, so that the temperature rise of the storage tank caused by BOG is avoided.

Description

Technical Field

[0001] This utility model relates to the field of liquid hydrogen addition technology, and more specifically to the field of liquid hydrogen addition machine technology. Background Technology

[0002] The current mainstream hydrogen refueling technology mainly uses high-pressure gaseous hydrogen (CGH2, 35 / 70MPa). This method has drawbacks such as low mass density, high-pressure safety hazards, and high energy consumption and cost, as detailed below:

[0003] Low mass density: The density of gaseous hydrogen storage is much lower than that of liquid hydrogen (liquid hydrogen density ≈ 70.8 kg / m³, gaseous hydrogen density ≈ 40 kg / m³ @ 70 MPa), which limits the amount of hydrogen that can be refueled per vehicle and makes it difficult to meet the range requirements of hydrogen-powered vehicles (such as heavy trucks and ships).

[0004] High-pressure safety hazards: Ultra-high-pressure compression systems require frequent start-ups and shutdowns, leading to a high risk of fatigue failure of valves and pipelines, and hydrogen can easily escape through micro-leakage points.

[0005] High energy consumption and cost: The energy consumption of hydrogen compression accounts for more than 60% of the total energy consumption of refueling, and the high cost of high-pressure storage tank materials (carbon fiber composite materials) restricts the large-scale promotion of hydrogen refueling stations.

[0006] Liquid hydrogen refueling machines are also currently in use. These machines are key devices specifically designed to refuel hydrogen fuel cell vehicles or other liquid hydrogen-powered devices with liquid hydrogen (LH□). Due to the extremely low storage temperature (-253°C) and high volatility of liquid hydrogen, refueling machines require highly specialized technology and safety design. Existing patents disclose the following technologies:

[0007] The patent with publication number CN97346057A, entitled "A Liquid Hydrogen Refueling System and Refueling Method," discloses the following: The liquid hydrogen refueling system includes a liquid hydrogen storage container, a target container, a purging pipeline, an exhaust pipeline, and a refueling device. In this liquid hydrogen refueling system, the pipeline configuration enables purging and pre-cooling before refueling, as well as monitoring and detection. It also enables both low-flow and high-flow refueling. In summary, this system achieves safe refueling of liquid hydrogen fuel cell vehicles, and the system is simple, low-cost, and has a precisely adjustable flow rate.

[0008] Patent publication number CN96293412B, entitled "An Automatic Liquid Hydrogen Dispensing Machine and Liquid Hydrogen Dispensing Method," discloses the following: The liquid hydrogen dispensing machine mainly includes a liquid hydrogen dispensing pipeline, a displacement purging pipeline, a small-flow pre-cooling pipeline, a return gas pipeline, a displacement venting pipeline, a main venting pipeline, a monitoring system, an automatic control system, a switch control valve, a safety valve, a pressure regulating valve, a filter, and a liquid hydrogen dispensing nozzle. The liquid hydrogen dispensing method is performed using the liquid hydrogen dispensing machine. The liquid hydrogen dispensing machine and method are suitable for civilian liquid hydrogen refueling stations and are applied to refueling scenarios for relatively small-flow liquid hydrogen fuel cell vehicles. They can achieve automated control of liquid hydrogen dispensing, automatically adjust the refueling speed, accurately measure the liquid hydrogen dispensing flow rate, use pre-cooling measures to reduce BOG generation, improve the dispensing rate, and achieve cold energy recovery.

[0009] While existing liquid hydrogen refueling technologies and the aforementioned patents attempt to address the BOG (Body-of-Gas) problem, they suffer from the following technical bottlenecks:

[0010] (1) BOG reliquefaction solution is uneconomical: Some patents rely on built-in liquefaction devices or external cryogenic compressors, which require additional refrigeration power, resulting in a surge in equipment investment and operation and maintenance costs, which does not meet the economic requirements of commercial hydrogen refueling stations.

[0011] (2) Side effects of BOG direct reinjection of liquid hydrogen storage tank:

[0012] 1) Risk of liquefaction failure: If the temperature of gaseous hydrogen (BOG) is higher than the saturation temperature of liquid hydrogen storage tank (such as the liquefaction temperature corresponding to the tank pressure), direct reinjection will not liquefy the hydrogen. Instead, it will cause the tank pressure to rise, triggering a safety release and wasting hydrogen.

[0013] 2) Potential for component imbalance: The gaseous hydrogen contains a high proportion of positive hydrogen (about 75% at room temperature). Direct reinjection into the liquid hydrogen storage tank may trigger the exothermic conversion of positive and negative hydrogen, exacerbating BOG generation and creating a vicious cycle. Utility Model Content

[0014] The purpose of this utility model is to provide a liquid hydrogen refueling machine in order to solve the above-mentioned technical problems.

[0015] To achieve the above objectives, this utility model specifically adopts the following technical solution:

[0016] This utility model provides a liquid hydrogen refueling machine, including a filling pipeline assembly, a return gas pipeline assembly, a precooling pipeline assembly, and a safety venting pipeline assembly. The filling pipeline assembly, the return gas pipeline assembly, and the precooling pipeline assembly are all connected to the safety venting pipeline assembly.

[0017] The filling pipeline assembly includes a liquid hydrogen storage tank with a liquid outlet pipe and a filling gun connected to the end of the liquid outlet pipe via a flexible connection;

[0018] The return gas pipeline assembly includes a return gas gun that mates with the liquid tank to be added, a first return gas pipeline connected to the return gas gun via a hose, a second return gas pipeline connected to the end of the first return gas pipeline, and a BOG return gas port connected to the end of the second return gas pipeline.

[0019] The precooling pipeline assembly includes a first precooling pipeline, a second precooling pipeline, and a third precooling pipeline; one end of the second precooling pipeline is connected to the return liquid port, and the other end is connected to the third precooling pipeline; the other end of the third precooling pipeline is connected to a gun holder; one end of the first precooling pipeline is connected to the middle of the outlet pipeline, and the other end of the first precooling pipeline is connected to the connection between the second and third precooling pipelines.

[0020] The connection between the second and third precooling pipes is also provided with a third return gas pipe that connects to the connection between the first and second return gas pipes.

[0021] A liquid flow meter is installed on the liquid outlet pipe at the rear end of the first precooling pipe, and a return gas flow meter is installed on the return gas pipe.

[0022] In one embodiment, the liquid outlet pipe, the first precooling pipe, and the second precooling pipe constitute a small-circulation precooling pipe system;

[0023] The liquid outlet pipe, the filling gun, the gun holder, the third precooling pipe, and the second precooling pipe constitute the large circulation precooling pipe system.

[0024] In one embodiment, a liquid flow meter, an emergency shut-off valve, a first pressure transmitter, and a break-off valve are sequentially installed on the liquid outlet pipe located at the rear end of the first precooling pipe. The liquid flow meter is located at the end away from the filling gun. A maintenance needle valve is installed on the connecting pipe between the pressure transmitter and the liquid outlet pipe. The first pressure transmitter includes a first field pressure gauge and a first remote pressure transmitter arranged in parallel.

[0025] In one embodiment, a shut-off valve, a filter, a second pressure transmitter, a flow regulating valve, and a temperature transmitter are sequentially installed on the liquid outlet pipe located at the front end of the first precooling pipe. The flow regulating valve is close to the liquid flow meter. The second pressure transmitter includes a second field pressure gauge. A maintenance needle valve is installed on the pipe connecting the second field pressure gauge and the liquid outlet pipe. The temperature transmitter includes a field temperature gauge and a remote temperature transmitter arranged in parallel.

[0026] In one embodiment, an emergency shut-off valve is installed on the first precooling pipe; an emergency shut-off valve and a shut-off valve are installed on the second precooling pipe; and a pressure transmitter and a check valve are sequentially installed on the third precooling pipe along the return direction.

[0027] In one embodiment, a breakaway valve, a check valve, and a return gas flow meter are sequentially installed on the first return gas pipeline in the direction of return flow; a shut-off valve is installed on the second return gas pipeline; and an emergency shut-off valve is installed on the third return gas pipeline.

[0028] In one embodiment, the safety venting pipeline assembly includes a first safety venting assembly, a second safety venting assembly, a third safety venting assembly, a fourth safety venting assembly, and a fifth safety venting assembly, wherein the vent ports of the first safety venting assembly, the second safety venting assembly, the third safety venting assembly, the fourth safety venting assembly, and the fifth safety venting assembly are connected to the venting port through a venting pipeline;

[0029] The first safety venting assembly and the second safety venting assembly are located on the front and rear sides of the flow regulating valve, respectively.

[0030] The third and fourth safety venting assemblies are located on the front and rear sides of the emergency shut-off valve of the second precooling pipe, respectively.

[0031] The fifth safety exhaust assembly is located on the second return air duct.

[0032] In one embodiment, the first safety venting assembly, the second safety venting assembly, the third safety venting assembly, the fourth safety venting assembly, and the fifth safety venting assembly each include a safety valve and a maintenance needle valve connected in series.

[0033] In one embodiment, the system further includes a displacement purging line comprising a hydrogen displacement purging assembly and a nitrogen displacement purging assembly arranged in parallel, the hydrogen displacement purging assembly and the nitrogen displacement purging assembly being combined and connected to the liquid outlet pipeline via a purging pipe.

[0034] In one embodiment, a needle valve is provided on the purge pipe, which is connected to the outlet pipe between the filter and the second pressure transmitter.

[0035] The beneficial effects of this utility model are as follows:

[0036] 1. The liquid flow meter is installed on the liquid outlet pipe at the rear end of the first precooling pipe. Even if the valve on the first precooling pipe leaks liquid hydrogen, the leaked liquid hydrogen will return to the liquid hydrogen storage tank along the second return gas pipe and will not be counted in the liquid flow meter on the liquid outlet pipe. This will not cause the liquid flow meter to malfunction and improve the billing accuracy of the liquid filling system.

[0037] 2. This solution, through a more scientific and reasonable design of the circulating precooling process, ensures that the liquid hydrogen dispenser can guarantee sufficient precooling of the pipeline system and core components during the large and small circulating precooling processes, while avoiding the impact of the gas phase flow meter on its service life and quality stability due to the scouring of the hydrogen cryogenic medium during the precooling process.

[0038] 3. After the filling gun is finished, close the liquid outlet of the filling gun. At this time, the filling gun and the filling hose contain liquid hydrogen, which vaporizes into gaseous BOG as the temperature rises. To prevent the hose from becoming pressurized when the filling gun is inserted into the gun holder, the gaseous BOG returns to the BOG return port through the one-way valve and the emergency shut-off valve HV04, avoiding excessive gas pressure in the filling gun and the filling hose, which could cause safety hazards.

[0039] 4. To prevent hose pressure buildup when the dispensing gun is not inserted into the dispensing gun holder: If no liquid is added for a long time, the hose will vaporize and increase in pressure due to heat absorption. At this time, the first pressure transmitter will detect that the pressure has reached the set value, and the emergency shut-off valve HV01 on the liquid outlet pipe will open, the emergency shut-off valve HV02 on the first precooling pipe will open, and the emergency shut-off valve HV04 on the third return gas pipe will open. BOG can return to the BOG return gas port through the second return gas pipe. Attached Figure Description

[0040] To more clearly illustrate the technical solutions of the embodiments of this utility model, the drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this utility model and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained from these drawings without creative effort.

[0041] Figure 1 These are schematic diagrams of the structures of Examples 1 to 5;

[0042] Figure 2 This is a structural schematic diagram of Example 6.

[0043] Attached diagram labels: 1-Liquid outlet pipe, 2-First precooling pipe, 3-Second return gas pipe, 4-First return gas pipe, 5-Vent pipe, 6-Second precooling pipe, 7-Displacement purging pipe, 8-Third return gas pipe, 9-Third precooling pipe, 10-Fourth return gas pipe. Detailed Implementation

[0044] To make the technical problems, technical solutions, and technical effects of this utility model clearer, the technical solutions of this utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments of this utility model. Obviously, the described embodiments are only some embodiments of this utility model, and not all embodiments. The components of the embodiments of this utility model described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0045] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0046] It should be noted that similar reference numerals and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures. Furthermore, the terms "first," "second," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0047] In the description of the embodiments of this utility model, it should be noted that the terms "inner", "outer", "upper", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the utility model product is usually placed when in use. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0048] Example 1

[0049] This embodiment provides a liquid hydrogen refueling machine, including a filling pipeline assembly, a return gas pipeline assembly, a precooling pipeline assembly, a safety venting pipeline assembly, and a displacement purging pipeline assembly. The filling pipeline assembly, the return gas pipeline assembly, the precooling pipeline assembly, and the displacement purging pipeline assembly are all connected to the safety venting pipeline assembly.

[0050] The filling pipeline assembly includes a liquid outlet pipeline 1 connected to the liquid hydrogen storage tank and a filling gun connected to the end of the liquid outlet pipeline 1 via a hose;

[0051] The return gas pipeline assembly includes a return gas gun that mates with the liquid tank to be added, a first return gas pipeline 4 connected to the return gas gun via a hose, a second return gas pipeline 3 connected to the end of the first return gas pipeline 4, and a BOG return gas port connected to the end of the second return gas pipeline 3.

[0052] The precooling pipeline assembly includes a first precooling pipeline 2, a second precooling pipeline 6, and a third precooling pipeline 9; one end of the second precooling pipeline 6 is connected to the return liquid port, and the other end is connected to the third precooling pipeline 9; the other end of the third precooling pipeline 9 is connected to a gun holder; one end of the first precooling pipeline 2 is connected to the middle of the liquid outlet pipeline 1, and the other end of the first precooling pipeline 2 is connected to the connection between the second precooling pipeline 6 and the third precooling pipeline 9.

[0053] The connection between the second precooling pipe 6 and the third precooling pipe 9 is also provided with a third return gas pipe 8 that connects to the connection between the first return gas pipe 4 and the second return gas pipe 3.

[0054] A liquid flow meter is installed on the liquid outlet pipe 1 located at the rear end of the first precooling pipe 2, and a return gas flow meter is installed on the return gas pipe 4.

[0055] Example 2

[0056] This embodiment is a further optimization based on Embodiment 1, specifically:

[0057] The liquid outlet pipe 1, the first precooling pipe 2, and the second precooling pipe 6 constitute a small circulation precooling pipe system; the liquid outlet pipe 1, the filling gun, the injection gun holder, the third precooling pipe 9, and the second precooling pipe 6 constitute a large circulation precooling pipe system.

[0058] A liquid flow meter, an emergency shut-off valve, a first pressure transmitter, and a break valve are sequentially installed on the liquid outlet pipe 1 located at the rear end of the first precooling pipe 2. The liquid flow meter is located at the end away from the filling gun. A maintenance needle valve is installed on the connecting pipe between the pressure transmitter and the liquid outlet pipe 1. The first pressure transmitter includes a first field pressure gauge and a first remote pressure transmitter arranged in parallel.

[0059] A shut-off valve, a filter, a second pressure transmitter, a flow regulating valve, and a temperature transmitter are sequentially installed on the liquid outlet pipe 1 located at the front end of the first precooling pipe 2. The flow regulating valve is close to the liquid flow meter. The second pressure transmitter includes a second field pressure gauge. A maintenance needle valve is installed on the pipe connecting the second field pressure gauge and the liquid outlet pipe 1. The temperature transmitter includes a field temperature gauge and a remote temperature transmitter arranged in parallel.

[0060] An emergency shut-off valve is installed on the first precooling pipe 2; an emergency shut-off valve and a stop valve are installed on the second precooling pipe 6; and a pressure transmitter and a check valve are installed sequentially on the third precooling pipe 9.

[0061] Specifically, the liquid hydrogen refueling process is as follows: Liquid hydrogen is transported through a pipeline into the outlet pipeline 1, and then passes through a shut-off valve, a filter, a second pressure transmitter, a flow regulating valve, a temperature transmitter, a liquid phase flow meter, an emergency shut-off valve, a first pressure transmitter, a breakaway valve, and finally connected to the hydrogen refueling gun through a hose.

[0062] The precooling process of the small circulation precooling pipeline system is as follows: Liquid hydrogen is transported into the outlet pipeline 1 through the pipeline, and then passes through the shut-off valve, filter, second pressure transmitter, flow regulating valve, and temperature transmitter. It then enters the second precooling pipeline 6 through the first precooling pipeline 2, and finally returns to the return port of the liquid hydrogen storage tank to precool the small circulation precooling pipeline system.

[0063] The precooling process of the large-circulation precooling pipeline system is as follows: Liquid hydrogen is transported into the outlet pipeline 1 through the pipeline, and then passes through the shut-off valve, filter, second pressure transmitter, flow regulating valve, temperature transmitter, liquid phase flow meter, emergency shut-off valve, first pressure transmitter, and break-off valve. It is then connected to the hydrogen refueling gun through a hose, and the hydrogen refueling gun is inserted into the refueling gun holder. It then enters the second precooling pipeline 6 through the third precooling pipeline 9, and finally returns to the return port of the liquid hydrogen storage tank to precool the large-circulation precooling pipeline system.

[0064] Example 3

[0065] This embodiment is a further optimization based on Embodiment 1, specifically:

[0066] The first return gas pipeline 4 is equipped with a break valve, a check valve, and a return gas flow meter in sequence according to the return flow direction; the second return gas pipeline 3 is equipped with a shut-off valve; and the third return gas pipeline 8 is equipped with an emergency shut-off valve.

[0067] Specifically, the return gas process is as follows: when the residual pressure of the vehicle cylinder is high, the hydrogen in the vehicle cylinder is returned to the BOG return gas port through the return gas gun, a one-way valve, and a return gas flow meter.

[0068] To prevent the hose from becoming pressurized when the dispensing gun is not inserted into the gun holder: If no liquid is added for a long time, the hose will vaporize and become pressurized due to heat absorption. At this time, the first pressure transmitter will detect that the pressure has reached the set value, and the emergency shut-off valve on the liquid outlet pipe 1 will open. The vaporized hydrogen can pass through the first precooling pipe 2, the third return gas pipe 8, and the second return gas pipe 3 to the BOG return gas port.

[0069] Example 4

[0070] This embodiment is a further optimization based on Embodiment 1, specifically:

[0071] The safety venting pipeline assembly includes a first safety venting assembly, a second safety venting assembly, a third safety venting assembly, a fourth safety venting assembly, and a fifth safety venting assembly. The venting ports of the first safety venting assembly, the second safety venting assembly, the third safety venting assembly, the fourth safety venting assembly, and the fifth safety venting assembly are connected to the venting port through the venting pipeline 5.

[0072] The first and second safety venting assemblies are located on the front and rear sides of the flow regulating valve, respectively; the third and fourth safety venting assemblies are located on the front and rear sides of the emergency shut-off valve of the second precooling pipe 6, respectively; and the fifth safety venting assembly is located on the second return gas pipe 3.

[0073] The first safety venting assembly, the second safety venting assembly, the third safety venting assembly, the fourth safety venting assembly, and the fifth safety venting assembly all include a safety valve and a maintenance needle valve connected in series.

[0074] Example 5

[0075] This embodiment is a further optimization based on embodiment 4, specifically:

[0076] It also includes a purge line 7, which comprises a hydrogen purge assembly and a nitrogen purge assembly arranged in parallel. The hydrogen purge assembly and the nitrogen purge assembly are combined and connected to the outlet pipeline 1 via a purge pipe. A needle valve is installed on the purge pipe, which is connected to the outlet pipeline 1 between the filter and the second pressure transmitter.

[0077] Specifically, pipeline purging: During equipment commissioning and maintenance, the inlet, return, and BOG pipelines are purged and replaced using an external gas source (nitrogen or hydrogen); nitrogen purging is performed first, followed by hydrogen replacement.

[0078] Example 6

[0079] like Figure 2 As shown, this embodiment is a further optimization based on embodiment 5, specifically:

[0080] The injection gun holder in Example 5 is divided into an injection gun holder and an injection gun circulation holder. A fourth return gas pipe 10 is added. The injection gun circulation holder is located at the rear end of the third precooling pipe 9 in Example 5. The position of the third return gas pipe 8 in Example 5 is adjusted. One end of the third return gas pipe 8 is connected to the liquid outlet pipe 1, and the other end of the third return gas pipe 8 is connected to the connection between the first return gas pipe 4 and the second return gas pipe 3. The injection gun holder is connected to one end of the fourth return gas pipe 10, and the other end of the fourth return gas pipe 10 is connected to the third return gas pipe 8 after the position is adjusted. A one-way valve in the return flow direction is provided on the fourth return gas pipe 10. An emergency shut-off valve and a one-way valve in the return flow direction are provided on the third return gas pipe 8 after the position is adjusted.

[0081] Specifically, to prevent the hose from becoming pressurized when the liquid filling gun is inserted into the gun holder: if no liquid is added for a long time, the hose will vaporize and become pressurized due to heat absorption, and the BOG can return to the BOG return port through the one-way valve.

[0082] To prevent hose pressure buildup when the filling gun is not inserted into the filling gun holder: If no liquid is added for a long time, the hose will vaporize and increase in pressure due to heat absorption. At this time, the first pressure transmitter will detect that the pressure has reached the set value. Then, the emergency shut-off valve on the liquid outlet pipe 1 will open, and the emergency shut-off valve and check valve on the third return gas pipe 8 after position adjustment will also open. BOG can return to the BOG return gas port through the emergency shut-off valve on the liquid outlet pipe 1, the emergency shut-off valve on the third return gas pipe 8, and the check valve on the third return gas pipe 8.

[0083] In addition, the flow regulating valve on the liquid outlet pipeline 1 can be a high-flow regulating valve and a low-flow regulating valve connected in parallel. That is, the flow can be regulated by means of flow regulating valve, orifice plate, or by adding a bypass (two parallel channels for high flow and low flow).

[0084] Before low-flow precooling in the pipeline: When the standby time is long, if the temperature transmitter on the liquid outlet pipeline 1 detects that the temperature of the liquid inlet pipeline exceeds the limit, the system opens the low-flow regulating valve to precool the liquid inlet pipeline with a low flow of liquid hydrogen, thus avoiding the generation of a large amount of BOG. ​​The precooled BOG returns to the BOG return port through the third return gas pipeline 8. When the temperature of the liquid inlet pipeline reaches the set value of the small-cycle precooling, the system restarts the small-cycle precooling. This can reduce the BOG production during precooling when the system has not been started for a long time.

Claims

1. A liquid hydrogen dispenser, characterized by comprising: The filling pipeline assembly, the gas return pipeline assembly, the pre-cooling pipeline assembly and the safety venting pipeline assembly are communicated with each other; The filling pipeline assembly comprises a liquid outlet pipeline (1) of a liquid hydrogen storage tank, a filling gun communicated with the liquid outlet pipeline (1) through a hose; The gas return pipeline assembly comprises a gas return nozzle matched with a tank body, a first gas return pipeline (4) communicated with the gas return nozzle through a hose, a second gas return pipeline (3) communicated with the first gas return pipeline (4) and a BOG gas return port connected with the second gas return pipeline (3); The pre-cooling pipeline assembly comprises a first pre-cooling pipeline (2), a second pre-cooling pipeline (6) and a third pre-cooling pipeline (9); one end of the second pre-cooling pipeline (6) is communicated with a liquid return port, the other end of the second pre-cooling pipeline (6) is communicated with the third pre-cooling pipeline (9), the other end of the third pre-cooling pipeline (9) is connected with a gun insertion seat, one end of the first pre-cooling pipeline (2) is communicated with a middle part of the liquid outlet pipeline (1), the other end of the first pre-cooling pipeline (2) is communicated with a connection part of the second pre-cooling pipeline (6) and the third pre-cooling pipeline (9); The connection part of the second pre-cooling pipeline (6) and the third pre-cooling pipeline (9) is further provided with a third gas return pipeline (8) communicated with a connection part of the first gas return pipeline (4) and the second gas return pipeline (3); A liquid phase flowmeter is arranged on the liquid outlet pipeline (1) at a rear end of the first pre-cooling pipeline (2), and a gas return flowmeter is arranged on the gas return pipeline (4).

2. The liquid hydrogen dispenser of claim 1, wherein, The liquid outlet pipeline (1), the first pre-cooling pipeline (2) and the second pre-cooling pipeline (6) constitute a small circulation pre-cooling pipeline system; The liquid outlet pipeline (1), the filling gun, the gun insertion seat, the third pre-cooling pipeline (9) and the second pre-cooling pipeline (6) constitute a large circulation pre-cooling pipeline system.

3. A liquid hydrogen dispenser as claimed in claim 2, wherein The liquid outlet pipeline (1) at the rear end of the first pre-cooling pipeline (2) is sequentially provided with a liquid phase flowmeter, an emergency shut-off valve, a first pressure transmitter and a pull-off valve; the liquid phase flowmeter is arranged at an end far from the filling gun; the pressure transmitter is provided with a maintenance needle valve on a connecting pipeline of the liquid outlet pipeline (1); and the first pressure transmitter comprises a first field pressure gauge and a first remote pressure transmitter arranged side by side.

4. The liquid hydrogen dispenser of claim 3, wherein, The liquid outlet pipeline (1) at the front end of the first pre-cooling pipeline (2) is sequentially provided with a shut-off valve, a filter, a second pressure transmitter, a flow regulating valve and a temperature transmitter; the flow regulating valve is close to the liquid phase flowmeter; the second pressure transmitter comprises a second field pressure gauge; the second field pressure gauge is provided with a maintenance needle valve on a pipeline connected with the liquid outlet pipeline (1); and the temperature transmitter comprises a field temperature gauge and a remote temperature transmitter arranged side by side.

5. A liquid hydrogen dispenser as claimed in claim 4, wherein The first pre-cooling pipeline (2) is provided with an emergency shut-off valve; the second pre-cooling pipeline (6) is provided with an emergency shut-off valve and a stop valve; the third pre-cooling pipeline (9) is provided with a pressure transmitter and a check valve in sequence along the backflow direction.

6. A liquid hydrogen dispenser as claimed in claim 5, wherein The first backflow pipeline (4) is provided with a pull-off valve, a check valve and a backflow flowmeter in sequence along the backflow direction; the second backflow pipeline (3) is provided with a stop valve; the third backflow pipeline (8) is provided with an emergency shut-off valve.

7. A liquid hydrogen dispenser as claimed in claim 6, wherein The safety venting pipeline assembly comprises a first safety exhaust assembly, a second safety exhaust assembly, a third safety exhaust assembly, a fourth safety exhaust assembly and a fifth safety exhaust assembly, exhaust ports of the first safety exhaust assembly, the second safety exhaust assembly, the third safety exhaust assembly, the fourth safety exhaust assembly and the fifth safety exhaust assembly are communicated with a venting port through a venting pipeline (5); The first safety exhaust assembly and the second safety exhaust assembly are respectively located on the front and back sides of the flow regulating valve; The third safety exhaust assembly and the fourth safety exhaust assembly are respectively located on the front and back sides of the emergency shut-off valve of the second pre-cooling pipeline (6); The fifth safety exhaust assembly is located on the second backflow pipeline (3).

8. A liquid hydrogen dispenser as claimed in claim 7, wherein The first safety exhaust assembly, the second safety exhaust assembly, the third safety exhaust assembly, the fourth safety exhaust assembly and the fifth safety exhaust assembly all comprise a safety valve and a maintenance needle valve in series.

9. A liquid hydrogen dispenser as claimed in claim 8, wherein, The replacement purge pipeline comprises a hydrogen replacement purge assembly and a nitrogen replacement purge assembly arranged side by side, the hydrogen replacement purge assembly and the nitrogen replacement purge assembly are combined and connected to the liquid outlet pipeline (1) through a purge pipeline.

10. The liquid hydrogen dispenser of claim 9, wherein, The purge pipeline is provided with a needle valve, and the purge pipeline is connected to the liquid outlet pipeline (1) between the filter and the second pressure transmitter.

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