A liquid hydrogen pressurized hydrogen refueling station and a method of operating the same

Abstract

This invention relates to a liquid hydrogen pressurized hydrogen refueling station and its operation method. The liquid hydrogen pressurized hydrogen refueling station includes a liquid hydrogen vaporization system, a hydrogen compression and storage system, a hydrogen refueling system, and a cold storage system. The liquid hydrogen pressurization pump (10) in the liquid hydrogen vaporization system pressurizes the liquid hydrogen, and the pressurized liquid hydrogen vaporizes into gaseous hydrogen, which is then transported to the hydrogen compression and storage system for storage. The stored hydrogen is used in the hydrogen refueling system. The cold storage system stores the cooling capacity generated during liquid hydrogen vaporization. Compared with the prior art, this invention has the advantages of energy saving and environmental protection by storing and utilizing the cooling capacity generated during hydrogen vaporization through the cold storage system; providing precise cooling to the cooling demand end with different temperature requirements by setting up multiple temperature-controlled cold boxes, extending the service life of the equipment; and increasing the cooling capacity per unit volume of the cold box by including a solid cold box in the cold storage system, thus reducing the construction cost of the hydrogen refueling station.

Description

Technical Field

[0001] This invention relates to a hydrogen refueling station, and more particularly to a liquid hydrogen pressurization type hydrogen refueling station and its operation method. Background Technology

[0002] Hydrogen refueling stations serve as the infrastructure for providing hydrogen to fuel cell vehicles. With the development of fuel cell vehicles, the demand for hydrogen refueling stations is experiencing explosive growth. Currently, liquid hydrogen storage-type refueling stations can be constructed using either a pressurization-then-vaporization or a vaporization-then-pressurization approach. Due to the immaturity of liquid hydrogen booster pump technology, the vaporization-then-pressurization approach is the conventional construction method. However, the vaporization-then-pressurization method suffers from problems such as short lifespan and low efficiency of the hydrogen compressor.

[0003] A search revealed that application publication number CN116428509A discloses a liquid hydrogen pressurization and refueling system driven by thermal pressurization and a hydrogen compressor. Specifically, it discloses that: a cryogenic high-pressure vessel and a hydrogen compressor are used as the core of the system; a low-power liquid hydrogen vaporization pressurization is achieved by co-driving the cryogenic high-pressure vessel with isochoric thermal pressurization and the hydrogen compressor with mechanical pressurization; and a vehicle-mounted storage tank is used for refueling in the form of cascaded high-pressure storage tanks; the pressurization process and the refueling process are deeply coupled, making full use of the cold energy of liquid hydrogen to achieve cooling of the hydrogen compressor and pre-cooling of the refueling hydrogen stream.

[0004] However, the patent does not detail the method for utilizing the cold energy of liquid hydrogen, particularly the method for storing and supplying the cold energy. Therefore, designing a liquid hydrogen refueling station capable of using the cold energy of liquid hydrogen to cool equipment with different temperature requirements is a problem that needs to be solved. Summary of the Invention

[0005] The purpose of this invention is to overcome the defects of the prior art and provide a liquid hydrogen pressurized hydrogen refueling station and its operation method.

[0006] The objective of this invention can be achieved through the following technical solutions:

[0007] According to one aspect of the present invention, a liquid hydrogen pressurized hydrogen refueling station is provided, comprising a liquid hydrogen vaporization system, a hydrogen compression and storage system, a hydrogen refueling system, and a cold storage system. The liquid hydrogen vaporization system includes a liquid hydrogen booster pump, which pressurizes the liquid hydrogen, vaporizes the pressurized liquid hydrogen into gaseous hydrogen, and then delivers it to the hydrogen compression and storage system for storage. The stored hydrogen is then used in the hydrogen refueling system. The cold storage system stores the cooling capacity generated during liquid hydrogen vaporization and includes at least two cold boxes and a cold storage heat exchange assembly to meet the cooling requirements of different temperature areas within the hydrogen refueling station.

[0008] As a preferred technical solution, the liquid hydrogen vaporization system further includes a liquid hydrogen storage tank and a liquid hydrogen vaporizer, wherein the liquid hydrogen storage tank is used to store liquid hydrogen and the liquid hydrogen vaporizer is used to vaporize the pressurized liquid hydrogen.

[0009] As a preferred technical solution, one of the two cold boxes is a primary cold box, which is equipped with a first temperature sensor and stores the cold energy generated in the liquid hydrogen gasification system through a cold storage and heat exchange component.

[0010] As a preferred technical solution, the primary cold box is a solid cold box that provides cooling capacity for the hydrogen compression and storage system.

[0011] As a preferred technical solution, the other of the two cold boxes is a secondary cold box. The secondary cold box is equipped with a second temperature sensor. The cold storage system also includes a heat exchange component. The secondary cold box is connected to the primary cold box through the heat exchange component to provide cooling capacity for the hydrogen refueling system.

[0012] As a preferred technical solution, the cold storage system further includes a three-stage cold box and a third temperature sensor. The three-stage cold box is connected to the two-stage cold box through a heat exchange component to provide cooling capacity for the hydrogen compressor in the hydrogen compression storage system. The hydrogen compressor is equipped with a compressor cooling mechanism connected to the three-stage cold box to cool the compressor body.

[0013] As a preferred technical solution, the hydrogen compression and storage system includes a 20MPa hydrogen storage cylinder, a 45MPa hydrogen compressor, a 45MPa hydrogen storage cylinder, a 90MPa hydrogen compressor, a 90MPa hydrogen storage cylinder, and a pre-cooling mechanism. The 45MPa hydrogen compressor pressurizes the hydrogen in the 20MPa hydrogen storage cylinder and stores it in the 45MPa hydrogen storage cylinder. The 90MPa hydrogen compressor pressurizes the hydrogen in the 45MPa hydrogen storage cylinder and stores it in the 90MPa hydrogen storage cylinder. The pre-cooling mechanism obtains cooling energy from the primary cold box to cool the hydrogen before it enters the hydrogen compressor.

[0014] As a preferred technical solution, the pre-cooling mechanism includes a 45MPa pre-cooling component, a 45MPa temperature sensor, a 90MPa pre-cooling component, and a 90MPa temperature sensor. The 45MPa pre-cooling component and the 45MPa temperature sensor are located between the inlet of the 45MPa hydrogen compressor and the first-stage cold box, and the 90MPa pre-cooling component and the 90MPa temperature sensor are located between the hydrogen inlet of the 90MPa hydrogen compressor and the first-stage cold box.

[0015] As a preferred technical solution, the hydrogen refueling system includes a 90MPa hydrogen refueling machine, a 45MPa hydrogen refueling machine, and a refueling heat exchange component. The 90MPa hydrogen refueling machine and the 45MPa hydrogen refueling machine are connected to a hydrogen compression and storage system, and the refueling heat exchange component is used to cool the hydrogen before refueling.

[0016] According to another aspect of the present invention, a method for operating a liquid hydrogen pressurized hydrogen refueling station is provided, wherein the liquid hydrogen vaporization system further includes a liquid hydrogen storage tank and a liquid hydrogen vaporizer; the hydrogen compression and storage system includes a 45MPa hydrogen compressor, a 45MPa hydrogen storage cylinder, a 90MPa hydrogen compressor, and a 90MPa hydrogen storage cylinder; and the hydrogen refueling system includes a 90MPa hydrogen dispenser and a 45MPa hydrogen dispenser.

[0017] The specific steps involved in this operation are as follows:

[0018] Step S1: Determine the type of hydrogen source. If it is liquid hydrogen, proceed to step S2; if it is gaseous hydrogen, proceed to step S3.

[0019] In step S2, the liquid hydrogen in the liquid hydrogen storage tank is pressurized to the required pressure by the liquid hydrogen booster pump, and the liquid hydrogen vaporizer vaporizes the liquid hydrogen into gaseous hydrogen and stores it in a 45MPa hydrogen storage bottle or a 90MPa hydrogen storage bottle.

[0020] In step S3, gaseous hydrogen is pressurized by a 45MPa hydrogen compressor and stored in a 45MPa hydrogen storage cylinder;

[0021] Step S4: According to the station's needs, the hydrogen in the 45MPa hydrogen storage cylinder is pressurized by a 90MPa hydrogen compressor, stored in a 90MPa hydrogen storage cylinder, and then used in a 90MPa hydrogen refueling machine; or the hydrogen in the 45MPa hydrogen storage cylinder is directly used in a 45MPa hydrogen refueling machine or a 90MPa hydrogen refueling machine; or the hydrogen in the 90MPa hydrogen storage cylinder is directly used in a 90MPa hydrogen refueling machine.

[0022] Compared with the prior art, the present invention has the following advantages:

[0023] 1) The liquid hydrogen booster hydrogen refueling station of the present invention first boosts the liquid hydrogen with a liquid hydrogen booster pump. After the boosted liquid hydrogen is vaporized, it has high pressure and can directly fill the high-pressure hydrogen storage cylinder. The process is simple, relieves the pressure of the hydrogen compressor, extends the service life of the hydrogen compressor, and reduces the failure rate of the hydrogen refueling station.

[0024] 2) This invention, by setting up a cold storage system, stores the cooling energy generated during hydrogen vaporization and applies it to equipment requiring cooling within the station, thereby reducing the operating costs of hydrogen refueling stations and saving energy and protecting the environment;

[0025] 3) The invention is equipped with multiple temperature cold boxes, which can accurately and quickly provide targeted cooling to the cold end with different temperature requirements. The hydrogen compression storage system, hydrogen filling system and hydrogen compressor can all be cooled, effectively extending the service life of the equipment.

[0026] 4) The cold storage system of the present invention includes a solid cold box, which increases the cold storage capacity per unit volume of the cold box and reduces the construction cost of hydrogen refueling stations. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the liquid hydrogen pressurized hydrogen refueling station of the present invention;

[0028] Figure 2 This is a schematic diagram of the hydrogen compressor structure of the present invention;

[0029] Figure 1 As indicated by the standard number:

[0030] 10. Liquid hydrogen booster pump; 11. Liquid hydrogen storage tank; 12. Liquid hydrogen vaporizer; 20. 20MPa hydrogen storage cylinder; 21. 45MPa hydrogen compressor; 22. 45MPa hydrogen storage cylinder; 23. 90MPa hydrogen compressor; 24. 90MPa hydrogen storage cylinder; 250. 45MPa temperature sensor; 251. 90MPa temperature sensor; 30. 90MPa hydrogen dispenser; 31. 45MPa hydrogen dispenser; 41. Primary cold box; 410. First temperature sensor; 42. Secondary cold box; 420. Second temperature sensor; 43. Tertiary cold box; 430. Third temperature sensor; 5. Refrigeration unit;

[0031] Figure 2 As indicated by the standard number:

[0032] 51. Cylinder head; 52. Cylinder block; 53. Compressor cooling coil; 54. Hydraulic oil. Detailed Implementation

[0033] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0034] The density of liquid hydrogen (70.85 kg / m³) 3 ) is gaseous hydrogen (0.089 kg / m³) 3 The hydrogen storage capacity of a liquid hydrogen storage station can be greatly increased compared to that of a gaseous hydrogen storage station (hereinafter referred to as a gaseous hydrogen refueling station) of the same scale.

[0035] For liquid hydrogen refueling stations, although the storage medium is liquid hydrogen, the refueling medium is still gaseous hydrogen. Therefore, before refueling fuel cell vehicles, the liquid hydrogen needs to be vaporized, releasing a large amount of cold energy. However, most existing liquid hydrogen refueling stations use ambient air vaporizers. In the vaporizer, the liquid hydrogen exchanges heat with the air and vaporizes, increasing its temperature. The air gains cold energy, which is then released into the atmosphere, resulting in a waste of cold energy. If this cold energy could be effectively utilized to pre-cool the input hydrogen to the hydrogen compressor, the energy consumption of the refueling station system could be significantly reduced, improving the economic efficiency of the liquid hydrogen refueling station. Therefore, designing a heat exchange system that can effectively utilize the cold energy released during the vaporization and heating process of liquid hydrogen to pre-cool the input hydrogen to the hydrogen compressor has high practical application value.

[0036] Currently, the on-board hydrogen storage system of fuel cell vehicles generally operates at a pressure of 35MPa or 70MPa. Hydrogen refueling stations are equipped with 22 sets of 45MPa hydrogen storage cylinders or 24 sets of 90MPa hydrogen storage cylinders, which are used for refueling fuel cell vehicles with pressures of 35MPa and 70MPa, respectively.

[0037] For hydrogen refueling stations with both 35MPa and 70MPa refueling capacities, depending on the hydrogen source, two-stage (45MPa and 90MPa) or three-stage (20MPa, 45MPa, and 90MPa) compressor units can be installed. The two-stage compressor unit is used for hydrogen refueling stations supplied by 20MPa hydrogen tubular vehicles. After the tubular vehicle arrives at the refueling station, the hydrogen storage cylinders (sets) on the vehicle are unloaded and connected to the refueling station system. The 45MPa compressor compresses the hydrogen in the tubular vehicle's storage cylinders (sets) to 45MPa and stores it in 45MPa hydrogen storage cylinders 22 (sets) at the refueling station. The 90MPa compressor compresses the hydrogen in 45MPa storage cylinders 22 (sets) to 90MPa and stores it in 90MPa hydrogen storage cylinders 24 (sets). The three-stage compressor unit is used for refueling stations supplied by pipelines, with on-site hydrogen production, or with liquid hydrogen. Taking a liquid hydrogen refueling station as an example, the liquid hydrogen in the liquid hydrogen storage tank 11 at the station is vaporized and heated to obtain low-pressure hydrogen (generally about 0.2 to 0.5 MPa). If this low-pressure hydrogen is directly compressed to 45 MPa, the temperature rise inside the compressor will become very serious due to the high compression ratio (45 / 0.2=225). Therefore, 20 MPa hydrogen storage cylinders 20 (sets) can be set up at the station. First, the low-pressure hydrogen is compressed to 20 MPa by the 20 MPa compressor and stored in the 20 MPa hydrogen storage cylinders 20 (sets). Then, the hydrogen in the 20 MPa hydrogen storage cylinders 20 (sets) is further compressed to 45 MPa by the 45 MPa compressor and stored in the 45 MPa hydrogen storage cylinders 22 (sets). Finally, the hydrogen in the 45 MPa hydrogen storage cylinders 22 (sets) is further compressed to 90 MPa by the 90 MPa compressor and stored in the 90 MPa hydrogen storage cylinders (sets) for subsequent use. Liquid hydrogen refueling stations using this design can also accept hydrogen supply from 20MPa tubular vehicles, enabling the refueling station to have both liquid and gaseous hydrogen storage capabilities.

[0038] However, during hydrogen compression, the compressor temperature rises sharply, even exceeding 180°C. Hydrogen-contaminated components such as the diaphragm can experience plastic instability and hydrogen-induced cracking under high temperature, high pressure, and alternating loads, easily leading to hydrogen leakage and reducing the compressor's operational reliability. Simultaneously, the high-temperature hydrogen output from the diaphragm compressor adversely affects hydrogen storage tanks (or stacks) at hydrogen refueling stations or onboard hydrogen storage tanks (or stacks) in fuel cell vehicles. Therefore, reducing the operating temperature of the diaphragm compressor is necessary. Currently, most diaphragm compressors have water-cooling devices at the hydrogen outlet. However, due to the freezing point of water, it is difficult to quickly cool the high-temperature compressor, and the cooling effect at the diaphragm end is not significant. Therefore, reducing the overall compressor temperature, especially the diaphragm end temperature (pre-cooling), is crucial.

[0039] The following example illustrates the role of pre-cooling in reducing the operating temperature of a hydrogen compressor.

[0040] Assuming the temperature T of the low-pressure hydrogen entering the compressor a =25 o C, P a =20MPa (approximately 200bar), after precooling in the precooling heat exchanger, the temperature drops to T. b =-40 o C, P a The pressure remained at 20 MPa. Subsequently, this portion of hydrogen entered the hydrogen compressor and was compressed to P. b =90MPa (approximately 900bar), the compression process is a polytropic process, and the compressor discharge temperature T needs to be measured. c The calculation first requires calculating the cylinder compression ratio. The calculation process for the compression ratio is as follows:

[0041] Absolute pressure (bar) = gauge pressure (bar) + 1 (bar), 1 bar = 1 × 10 5 Pa

[0042] Initial intake pressure is =200+1=201bar

[0043] Exhaust pressure =900+1=901bar

[0044] Then the compression ratio can be calculated:

[0045]

[0046] Using a single-stage compression method, the compressor's discharge temperature is calculated based on a determined compression ratio. Taking a diaphragm compressor as an example, the discharge temperature calculation formula is as follows:

[0047] (Unit: K)

[0048] in: The exhaust temperature, Intake air temperature, Where m is the compression ratio and m is the polytropic index.

[0049] Taking the polytropic process exponent m = 1.12, the exhaust temperature of the hydrogen compressor can be calculated as follows:

[0050]

[0051] If the traditional back-end cooling method is still used, the compressor outlet temperature can be calculated:

[0052]

[0053] It is evident that placing a pre-cooling heat exchanger at the inlet end can significantly reduce the compressor's exhaust temperature (from 350.12K to 273.61K), which is beneficial for extending the compressor's service life. The above calculations are under ideal conditions; in practical applications, the temperature of the compressed hydrogen can rise to 180℃. When the compressor operates at temperatures consistently above 180℃, on the one hand, hydrogen-exposed components such as the diaphragm age faster; on the other hand, since the optimal operating temperature of hydraulic oil 54 is 20-60℃, the high temperature will accelerate the emulsification and oxidation of the hydraulic oil 54, shortening its service life. In existing technologies, water cooling is typically used to cool the compressor cylinder head to achieve overall compressor cooling. However, limited by the freezing point of water, heat exchange efficiency, and the thickness of the cylinder head metal, it is difficult to reduce the internal temperature of the compressor. Therefore, pre-cooling the hydrogen before it enters the compressor is crucial.

[0054] Both hydrogen compression and refueling require cooling of the hydrogen before compression and refueling. Liquid hydrogen itself contains cold energy, and the cold energy released during vaporization is substantial; therefore, the rational utilization of this cold energy is crucial. Since the generation and usage of cold energy are not matched, it is essential to establish a cold energy storage device to store the cold energy released during the vaporization of liquid hydrogen and to pre-cool the hydrogen according to the operational needs of the hydrogen compressor and before refueling.

[0055] Taking a liquid hydrogen refueling station with both 35MPa and 70MPa refueling capacities as an example (calculated based on the maximum cooling energy demand), the station is equipped with a three-stage compression system consisting of a 20MPa compressor, a 45MPa compressor, and a 90MPa compressor, as well as 20 sets of 20MPa hydrogen storage cylinders, 22 sets of 45MPa hydrogen storage cylinders, and 24 sets of 90MPa hydrogen storage cylinders connected in series. The hydrogen inlet temperature of the 20MPa compressor is maintained at T0 = -40°C by adjusting the outlet temperature of the liquid hydrogen vaporizer 12. Assuming the output hydrogen pressure of the liquid hydrogen vaporizer 12 is 0.2MPa, a pre-cooling heat exchanger is used to cool the inlet hydrogen temperature of the 45MPa and 90MPa compressors to T0 = -20°C. o C. The outlet hydrogen temperature of each compressor is calculated as follows:

[0056] 45MPa compressor: outlet hydrogen temperature =276K

[0057] 90MPa compressor: outlet hydrogen temperature =273K

[0058] In the formula, m=1.12 is the polytropic index, and ε is the compression ratio. , .

[0059] The cooling energy requirements of the entire liquid hydrogen refueling station's compression system include: (i) cooling the inlet hydrogen of a 1kg 45MPa compressor to -20°C. o C requires cold energy E1; (ii) cooling the inlet hydrogen of the 1kg 90MPa compressor to -20 o (iii) The required cold energy E2 for C; (iii) The required cold energy E3 for cooling 1 kg of hydrogen at 70 MPa (-40 °C) (assuming maximum cold energy demand); E1, E2 and E3 can be calculated as follows by referring to the enthalpy values ​​of hydrogen at different pressures and temperatures provided on the website of the National Institute of Standards and Technology (NIST) (Table 1):

[0060] E1 = 4144.2 - 3949.4 = 194.8 kJ

[0061] E2 = 4267.7 - 3983.9 = 283.8 kJ

[0062] E3 = 4633.1 - 3983.9 = 649.2 kJ

[0063] Table 1. Enthalpy values ​​of hydrogen at different pressures and temperatures.

[0064]

[0065] Therefore, the total cooling energy required by the main cooling section of the entire hydrogen refueling station is E = E1 + E2 + E3 = 194.8 + 283.8 + 649.2 = 1127.8 kJ. In reality, the cooling energy required by a hydrogen refueling station is far greater than the theoretical calculation above. Therefore, using additional cooling methods would significantly increase the operating costs of the hydrogen refueling station, which is detrimental to energy conservation and environmental protection.

[0066] Theoretically, 1 kg of liquid hydrogen can be vaporized from 20 K and heated to -40 K. o The cold energy released at C (233.15K) is 3011kJ, far greater than 1127.8kJ. Hydrogen compression and refueling require a large amount of cooling energy; therefore, storing and reusing as much of the cooling energy as possible during liquid hydrogen vaporization can reduce the operating costs of hydrogen refueling stations. Simultaneously, the remaining cooling energy from liquid hydrogen vaporization can be used for station air conditioning and cold storage, achieving energy conservation and environmental protection. However, due to the enormous amount of cooling energy released during liquid hydrogen vaporization, the specific heat capacity of most liquid cryogenic working fluids is around 2kJ / (kg·K), with 2-methylpentane and isohexane having relatively low melting points (<-150℃). o C), higher boiling point (>40) o C (which does not vaporize at room temperature) can be used as a cryogenic working fluid in liquid hydrogen refueling stations. Taking 2-methylpentane as an example, for a liquid hydrogen refueling station with a liquid hydrogen storage capacity of 1000 kg and a peak hydrogen refueling capacity of ≥1000 kg / day, the minimum mass of 2-methylpentane required to store all the cold energy generated during liquid hydrogen vaporization is:

[0067] M1 = 1000 × E / (C 2-甲基戊烷 × (room temperature (25) o C) Melting point 2-甲基戊烷 ))

[0068] 1000*3011 / 2.24*(25-(-154))=7510Kg

[0069] The density of 2-methylpentane is 0.653 × 10⁻⁶. 3 kg / m 3 Therefore, the volume of the cold box storing the above-mentioned 2-methylpentane must at least meet the following requirements:

[0070] V1=7510 / (0.653×10 3 )=11.5m 3

[0071] However, since land is a non-renewable resource, the large footprint of liquid hydrogen refueling stations hinders their widespread application. Furthermore, cryogenic working fluids such as 2-methylpentane are often hazardous chemicals with extremely high prices; for example, 500mL of 2-methylpentane costs as much as 1300 yuan, significantly increasing the construction and maintenance costs of refueling stations and raising safety hazards within the stations. Because high-pressure gaseous hydrogen needs to be cooled to -40℃ before refueling, the maximum temperature of the primary cold box 41 cannot exceed -40℃. Even using cryogenic working fluids with slightly lower prices and higher melting points, such as n-hexane, still presents issues of price and land area requirements. Therefore, resolving the issues of cold storage capacity and the land area required for cold storage devices is one of the keys to reducing the construction and operating costs of hydrogen refueling stations.

[0072] If a cheaper and more stable aluminum solid-state cold box is used instead, the required quality of aluminum...

[0073] M2 = 1000 × E / (C 铝 × (room temperature (25) o C) Boiling point 液氢 ))

[0074] =1000×3011 / 0.9×(25-(-253))=12034kg

[0075] The density of aluminum is 2.7 × 10⁻⁶. 3 kg / m 3 Therefore, the volume of the cold box for storing the aforementioned aluminum must at least meet the following requirements.

[0076] V2=12034 / (2.7×10 3 )=4.5m 3

[0077] Aluminum metal cold boxes occupy a much smaller area than liquid cryogenic working fluid cold boxes. Therefore, the solid-state primary cold box 41 used in this invention has significant advantages over cryogenic liquid working fluid cold boxes in terms of floor space, cost, safety, and subsequent maintenance. The melting point, boiling point, and specific heat capacity of common cryogenic working fluids are shown in Table 2.

[0078] Table 2 Melting point, boiling point, and specific heat capacity of common low-temperature working fluids

[0079]

[0080] The main cooling components of a hydrogen refueling station are the hydrogen compressor and the hydrogen dispenser. Since the actual temperature at the hydrogen outlet of the hydrogen compressor exceeds 180℃, while the compressor's optimal operating temperature is 20-60℃, if pre-cooling is used, the hydrogen temperature should drop by approximately 120-160℃, meaning the hydrogen needs to cool from room temperature to -135℃ before entering the compressor. In contrast, the hydrogen in 35MPa and 75MPa hydrogen dispensers needs to be pre-cooled to -20℃ and -40℃ respectively before dispensing, a temperature drop of approximately 45-70℃, far lower than that of the hydrogen compressor. Furthermore, because the compressor has a wider optimal operating temperature range, the requirements for the cooling device are lower, while the pre-cooling temperature of the hydrogen dispenser is more precise, placing higher demands on the cooling device. Therefore, both the hydrogen compressor and the hydrogen dispenser draw cooling energy from a single cold box. However, the single temperature of the cold box cannot adequately meet the needs of both. Furthermore, the randomness of hydrogen compression and dispensing results in a large temperature variation range in the cold box, increasing the difficulty of temperature control for the hydrogen dispenser, which requires precise temperature control. Therefore, it is necessary to install two cold boxes to separately meet the needs of the hydrogen dispenser and the hydrogen compressor.

[0081] This invention provides a liquid hydrogen pressurized hydrogen refueling station, comprising a liquid hydrogen vaporization system for vaporizing liquid hydrogen into hydrogen gas, a hydrogen compression storage system for pressurizing and storing the hydrogen gas, a hydrogen refueling system for end-point refueling, a cold storage system for storing the cold energy from the vaporized liquid hydrogen and cooling the hydrogen compression storage system and the hydrogen refueling system, and a refrigeration device 5 for providing cooling energy when the cold storage system's cooling capacity is insufficient. The liquid hydrogen booster pump 10 in the liquid hydrogen vaporization system pressurizes the liquid hydrogen, and the pressurized liquid hydrogen vaporizes into gaseous hydrogen, which is then transported to the hydrogen compression system for storage. The stored hydrogen is used in the hydrogen refueling system when needed. Liquid hydrogen refers to liquid hydrogen gas, and gaseous hydrogen refers to gaseous hydrogen gas.

[0082] The liquid hydrogen vaporization system includes a liquid hydrogen storage tank 11 for storing liquid hydrogen, a liquid hydrogen booster pump 10 for pressurizing the liquid hydrogen in the liquid hydrogen storage tank 11, and a liquid hydrogen vaporizer 12 for vaporizing the pressurized liquid hydrogen. The vaporized hydrogen is stored in a hydrogen compression storage system.

[0083] The hydrogen compression and storage system includes a 20MPa hydrogen storage cylinder 20, a 45MPa hydrogen compressor 21 that pressurizes the hydrogen in the 20MPa hydrogen storage cylinder 20, a 45MPa hydrogen storage cylinder 22 that stores the hydrogen pressurized by the 45MPa hydrogen compressor 21, a 90MPa hydrogen compressor 23 that pressurizes the hydrogen in the 45MPa hydrogen storage cylinder 22, a 90MPa hydrogen storage cylinder 24 that stores the hydrogen pressurized by the 90MPa hydrogen compressor 23, and a pre-cooling mechanism that cools the hydrogen before it enters each compressor. The pre-cooling mechanism obtains cooling energy from a primary cold box 41 to cool the hydrogen before it enters the hydrogen compressor.

[0084] The pre-cooling mechanism includes a 45MPa precooling component, a 45MPa temperature sensor 250, a 90MPa precooling component, and a 90MPa temperature sensor 251. The 45MPa precooling component and the 45MPa temperature sensor 250 are located between the inlet of the 45MPa hydrogen compressor 21 and the first-stage cold box 41. The 90MPa precooling component and the 90MPa temperature sensor 251 are located between the hydrogen inlet of the 90MPa hydrogen compressor 23 and the first-stage cold box 41.

[0085] The hydrogen refueling system includes a 90MPa hydrogen refueling machine 30, a 45MPa hydrogen refueling machine 31, and a refueling heat exchange assembly for cooling the hydrogen before refueling. The 90MPa hydrogen refueling machine 30 and the 45MPa hydrogen refueling machine 31 are connected to a hydrogen compression and storage system. The refueling heat exchange assembly obtains cooling energy from a secondary cold box 42, which is used to cool the hydrogen before refueling.

[0086] When refueling a 35MPa vehicle, hydrogen from the 45MPa hydrogen storage cylinder 22 is used directly. When refueling a 70MPa vehicle, hydrogen from the 45MPa hydrogen storage cylinder 22 is used first, and when a certain pressure is reached, hydrogen from the 90MPa hydrogen storage cylinder 24 is used to continue refueling. This reduces the energy consumption of the hydrogen refueling station.

[0087] The cold storage system comprises multiple cold boxes at different temperatures to meet the varying cooling requirements of the hydrogen refueling station. Specifically, the system includes: a primary cold box 41 that directly stores the cooling capacity during liquid hydrogen vaporization; a heat exchange assembly for storing the cooling capacity of the liquid hydrogen vaporization within the primary cold box 41; a first temperature sensor 410 for detecting the temperature inside the primary cold box 41; a secondary cold box 42 connected to the primary cold box 41 via a heat exchange mechanism and having a higher temperature than the primary cold box 41; and a second temperature sensor 420 for monitoring the temperature inside the secondary cold box 42. The primary cold box 41 is solid, and the surfaces of the heat exchange assembly in contact with air are covered with insulation material. The number and installation locations of the cold boxes can be determined based on the actual conditions of the hydrogen refueling station, and solid cold boxes or cold boxes using other working fluids can be selected as needed.

[0088] Storing the cold energy within liquid hydrogen through a cold storage system offers several advantages over ambient air vaporizers. Firstly, it allows for the reuse of cold energy, saving energy. Secondly, because liquid hydrogen's temperature is lower than liquid oxygen, ambient air vaporizers, especially the bare tubes, can liquefy oxygen in the air due to their extremely low temperature, leading to liquid oxygen accumulation and posing a safety hazard. Cold storage heat exchange components rapidly absorb and convert the cold energy from liquid hydrogen for storage, eliminating this risk of liquid oxygen buildup.

[0089] Hydrogen compressors are key components of hydrogen refueling stations. They compress hydrogen to 20–90 MPa, allowing it to be used for refueling fuel cell vehicles or stored in high-pressure hydrogen storage tanks (or reservoirs). Compressors can be categorized into three main types based on their operating principle: positive displacement, dynamic, and thermal. Diaphragm compressors, a type of positive displacement compressor, use a piston in a cylinder to push hydraulic oil 54 in the cylinder's oil chamber. This hydraulic oil 54, after passing through a distribution plate, evenly pushes a diaphragm in the cavity formed between the cylinder head 51 and the distribution plate, changing the volume of the cylinder's gas chamber. With the intake and exhaust valves working in conjunction, this achieves the purpose of compressing and delivering the gas. This compression method produces no secondary pollution, provides excellent protection for the compressed gas, and features a high compression ratio, good sealing, and protection against contamination from lubricating oil and other solid impurities. Therefore, diaphragm compressors are the best choice for hydrogen pressurization and are used by the vast majority of hydrogen refueling stations.

[0090] Typically, the actual outlet temperature of hydrogen from a hydrogen compressor reaches as high as 180°C, while the optimal operating temperature for a hydrogen compressor is 20-60°C. To ensure the compressor operates at this optimal temperature, the hydrogen entering the compressor needs to be cooled by 120-160°C, from room temperature (25°C) to -95-135°C. The temperature of the cold box providing cooling for the compressor should be below -95°C. For a hydrogen refueling machine, however, the hydrogen needs to be pre-cooled to -20-40°C before refueling, from room temperature (25°C) to -20-40°C. The temperature of the cold box providing cooling for the refueling system should be below -40°C. Therefore, the cooling rates for the hydrogen entering the compressor and before refueling differ. If both draw cooling from the same ultra-low temperature source, the extremely low temperature of the source will be too low for the refueling machine, potentially causing overcooling. Furthermore, the temperature requirement for hydrogen before refueling is quite precise, while the temperature range required by the hydrogen compressor is wide. Drawing cooling capacity from a single cold source will cause rapid temperature changes in the cold boxes, making it difficult to control the hydrogen before refueling. Therefore, multiple cold boxes are necessary. For the primary cold box 41, which provides cooling capacity to the hydrogen compressor, its temperature should be below -95℃. Considering heat exchange efficiency, the preferred temperature is below -120℃. Since the temperature of liquid hydrogen is approximately -253℃, if the temperature of the primary cold box 41 reaches below -200℃, the large temperature difference with the ambient temperature hydrogen entering the hydrogen compressor will result in wasted cooling capacity. Therefore, the preferred temperature range for the primary cold box 41 is -120℃ to -150℃. For the secondary cold box 42, which provides cooling capacity to the hydrogen before refueling, its temperature should be below -40℃. Similarly, considering heat exchange and other issues, the preferred temperature range is -55℃ to -75℃. Because the temperature of the primary cold box 41 is relatively low, using a solid-state cold box allows it to store more cold energy while maintaining a lower temperature, and also reduces the footprint of the cold box, thus lowering the construction cost of the hydrogen refueling station. The storage capacity of the cold energy in the secondary cold box 42 is relatively small, so its material can be either liquid or solid.

[0091] To further extend the service life of hydrogen compressors, in addition to pre-cooling the hydrogen entering the compressor, cooling the compressor itself can also be achieved. For example... Figure 2As shown, the cylinder head 51 and cylinder block 52 of the hydrogen compressor are equipped with interconnected compressor cooling coils 53. The flow direction of the cryogenic working fluid in the compressor cooling coils 53 is from the cylinder head 51 to the cylinder block 52. Since the cylinder head 51 is located at the higher temperature hydrogen compression end, it can be cooled to a lower temperature. The cylinder block 52 is partially located at the hydraulic oil 54 end, and its optimal operating temperature (hydraulic oil 20-60℃) is higher than that of the cylinder head 51 end. Therefore, the lower temperature cryogenic working fluid absorbs some heat from the cylinder head 51 and then flows through the cylinder block 52 for cooling, which can keep both the cylinder head 51 and the cylinder block 52 at a suitable operating temperature. If the secondary cold box 42 provides cooling capacity to the hydrogen compressor, it is easy to cause the temperature to be too low. Therefore, in the cold storage system, a tertiary cold box 43 with a higher temperature than the secondary cold box 42 is set up and connected to the secondary cold box 42 through heat exchange components to provide cooling capacity to the hydrogen compressor. The tertiary cold box 43 is equipped with a third temperature detector for monitoring the temperature inside the tertiary cold box 43. Because the hydrogen compressor body requires relatively low cooling capacity, the temperature of the three-stage cold box 43 can be -10~0℃. The three-stage cold box 43 provides cooling capacity for the 45MPa hydrogen compressor 21 and the 90MPa hydrogen compressor 23. The 45MPa hydrogen compressor 21 and the 90MPa hydrogen compressor 23 are equipped with compressor cooling mechanisms connected to the three-stage cold box 43 to cool down the hydrogen compressor body.

[0092] The cold storage and heat exchange assembly includes a heat exchanger located on the liquid hydrogen vaporization unit, a heat exchange pipe connecting the heat exchanger and the primary cold box 41, a cryogenic working fluid located within the heat exchange pipe, and a cold storage circulation pump located on the heat exchange pipe. Because the cold energy released during hydrogen vaporization is enormous and the temperature is extremely low, the cryogenic working fluid in the heat exchange pipe is one or more of the following: helium, nitrogen, dichloromethane, 2-methylpentane, 3-methylpentane, 2-2-methylbutane, 2-3-methylbutane, toluene, and isohexane.

[0093] When the hydrogen source is gaseous hydrogen for a period of time, the remaining cooling capacity in each cold box is insufficient to cool the various devices requiring cooling in the hydrogen refueling station. Therefore, a refrigeration unit 5 is installed in the hydrogen refueling station to provide additional cooling for each device, ensuring the safe and stable operation of the station. Similarly, when the hydrogen source is liquid hydrogen, the initial cooling capacity released during liquid hydrogen vaporization is insufficient, resulting in the cold box temperatures being inadequate for cooling the devices. This can also be addressed by the refrigeration unit 5.

[0094] This invention also provides an operation method for a liquid hydrogen pressurized hydrogen refueling station:

[0095] When the hydrogen source is liquid hydrogen, according to the station's demand for gaseous hydrogen pressure, the liquid hydrogen in the liquid hydrogen storage tank 11 is pressurized to the required pressure by the liquid hydrogen booster pump 10, and then the pressurized liquid hydrogen is vaporized by the liquid hydrogen vaporizer 12 and stored in the 45MPa or 90MPa hydrogen storage cylinder 24.

[0096] Correspondingly, the cold storage and heat exchange mechanism stores the cooling capacity of the vaporized liquid hydrogen in the primary cold box 41. Simultaneously, when the second temperature sensor 420 detects that the temperature in the secondary cold box 42 is higher than the high-temperature setpoint, a portion of the cooling capacity from the primary cold box 41 is transferred to the secondary cold box 42 via heat exchange pipes. Heat exchange stops when the second temperature sensor 420 detects that the temperature in the secondary cold box 42 is lower than the low-temperature setpoint. Simultaneously, the pre-cooling component in the hydrogen compression and storage system begins operation. When the 45MPa temperature sensor 250 or the 90MPa temperature sensor 251 detects that the hydrogen temperature at the inlet of the corresponding hydrogen compressor is higher than the high-temperature setpoint, the hydrogen refueling station activates the corresponding 45MPa or 90MPa pre-cooling component for cooling and pre-cooling. Cooling stops when the 45MPa temperature sensor 250 or the 90MPa temperature sensor 251 detects that the temperature of the corresponding hydrogen compressor is lower than the low-temperature setpoint. When the hydrogen refueling machine is running, the hydrogen gas before refueling is cooled by the secondary cold box 42, so that the temperature of the hydrogen gas before refueling is reduced to -20℃ (45MPa hydrogen refueling machine 31) or -40℃ (90MPa hydrogen refueling machine 30).

[0097] When the hydrogen source is low-pressure hydrogen, such as hydrogen pipelines or low-pressure tube bundle vehicles, the hydrogen in the low-pressure hydrogen cylinder is pressurized by a 45MPa hydrogen compressor 21 and stored in a 45MPa hydrogen storage cylinder 22. Depending on the station's needs, it may be pressurized by a 90MPa hydrogen compressor 23, stored in a 90MPa hydrogen storage cylinder 24, and used in a 75MPa hydrogen dispenser; or the hydrogen in the 45MPa hydrogen storage cylinder 22 may be directly used in a 45MPa hydrogen dispenser 31 or a 90MPa hydrogen dispenser 30. If the hydrogen source is gaseous hydrogen for an extended period, and the first temperature sensor 410, second temperature sensor 420, third temperature sensor 430, 45MPa temperature sensor 250, or 90MPa temperature sensor 251 detects that the cooling capacity in the primary cold box 41, secondary cold box 42, tertiary cold box 43, 45MPa hydrogen compressor 21, or 90MPa hydrogen compressor 23 is insufficient for the corresponding cooling device, then the refrigeration device 5 will be activated for cooling.

[0098] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in the present invention, and these modifications or substitutions should all be covered within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A liquid hydrogen pressurized hydrogen refueling station, characterized by, The system comprises a liquid hydrogen gasification system, a hydrogen compression and storage system, a hydrogen refueling system and a cold storage system, the liquid hydrogen gasification system comprises a liquid hydrogen booster pump (10) which boosts the liquid hydrogen, the boosted liquid hydrogen is gasified into gaseous hydrogen and then delivered to the hydrogen compression and storage system for storage, and the stored hydrogen is used in the hydrogen refueling system; The cold storage system stores the cold energy generated during the gasification of liquid hydrogen, and comprises at least two cold boxes and a cold storage heat exchange assembly to meet the different temperature requirements of the cold demand end in the hydrogen refueling station; One of the two cold boxes is a first-level cold box (41), the first-level cold box (41) is provided with a first temperature sensor (410), and the first-level cold box (41) stores the cold energy generated in the liquid hydrogen gasification system through the cold storage heat exchange assembly; The first-level cold box (41) is a solid cold box and provides cold energy for the hydrogen compression and storage system; The other of the two cold boxes is a second-level cold box (42), the second-level cold box (42) is provided with a second temperature sensor (420), the cold storage system further comprises a heat exchange assembly, and the second-level cold box (42) is connected with the first-level cold box (41) through the heat exchange assembly and provides cold energy for the hydrogen refueling system; The hydrogen compression and storage system comprises a 20MPa hydrogen storage bottle (20), a 45MPa hydrogen compressor (21), a 45MPa hydrogen storage bottle (22), a 90MPa hydrogen compressor (23), a 90MPa hydrogen storage bottle (24) and a pre-cooling mechanism, the 45MPa hydrogen compressor (21) boosts the hydrogen in the 20MPa hydrogen storage bottle (20) and stores the boosted hydrogen in the 45MPa hydrogen storage bottle (22), the 90MPa hydrogen compressor (23) boosts the hydrogen in the 45MPa hydrogen storage bottle (22) and stores the boosted hydrogen in the 90MPa hydrogen storage bottle (24), and the pre-cooling mechanism obtains cold energy from the first-level cold box (41) and cools the hydrogen before entering the hydrogen compressor.

2. A liquid hydrogen booster hydrogen refuelling station according to claim 1, characterised in that, The liquid hydrogen gasification system further comprises a liquid hydrogen storage tank (11) for storing liquid hydrogen and a liquid hydrogen gasifier (12) for gasifying the boosted liquid hydrogen.

3. A liquid hydrogen booster hydrogen refuelling station according to claim 1, characterised in that, The cold storage system further comprises a third-level cold box (43) and a third temperature sensor (430), the third-level cold box (43) is connected with the second-level cold box (42) through a heat exchange assembly and provides cold energy for the hydrogen compressor in the hydrogen compression and storage system, and the hydrogen compressor is provided with a compressor cooling mechanism connected with the third-level cold box (43) and used for cooling the hydrogen compressor body.

4. A liquid hydrogen booster hydrogen refueling station according to claim 1, wherein, The pre-cooling mechanism comprises a 45MPa pre-cooling assembly, a 45MPa temperature sensor (250), a 90MPa pre-cooling assembly and a 90MPa temperature sensor (251), the 45MPa pre-cooling assembly and the 45MPa temperature sensor (250) are located between the inlet of the 45MPa hydrogen compressor (21) and the first-level cold box (41), and the 90MPa pre-cooling assembly and the 90MPa temperature sensor (251) are located between the hydrogen inlet of the 90MPa hydrogen compressor (23) and the first-level cold box (41).

5. A liquid hydrogen booster hydrogen refueling station according to claim 1, wherein The hydrogen refueling system comprises a 90MPa hydrogen refueling machine (30), a 45MPa hydrogen refueling machine (31) and a refueling heat exchange assembly, the 90MPa hydrogen refueling machine (30) and the 45MPa hydrogen refueling machine (31) are connected with the hydrogen compression and storage system, and the refueling heat exchange assembly is used for cooling hydrogen before refueling.

6. A method of operating a liquid hydrogen refueling station as claimed in claim 1, characterized in that, The liquid hydrogen gasification system further comprises a liquid hydrogen storage tank (11) and a liquid hydrogen gasifier (12); the hydrogen compression and storage system comprises a 45MPa hydrogen compressor (21), a 45MPa hydrogen storage bottle (22), a 90MPa hydrogen compressor (23) and a 90MPa hydrogen storage bottle (24); the hydrogen refueling system comprises a 90MPa hydrogen refueling machine (30) and a 45MPa hydrogen refueling machine (31); The operation method specifically comprises the following steps: Step S1, judging the hydrogen source type, if it is liquid hydrogen, executing step S2; if it is gaseous hydrogen, executing step S3; Step S2, liquid hydrogen in the liquid hydrogen storage tank (11) is pressurized to a required pressure by a liquid hydrogen booster pump (10), and the liquid hydrogen gasifier (12) gasifies the liquid hydrogen into gaseous hydrogen and stores the gaseous hydrogen in the 45MPa hydrogen storage bottle (22) or the 90MPa hydrogen storage bottle (24); Step S3, gaseous hydrogen is pressurized by the 45MPa hydrogen compressor (21) and stored in the 45MPa hydrogen storage bottle (22); Step S4, according to the demand in the station, hydrogen in the 45MPa hydrogen storage bottle (22) is pressurized by the 90MPa hydrogen compressor (23) and stored in the 90MPa hydrogen storage bottle (24) and applied to the 90MPa hydrogen refueling machine (30); or hydrogen in the 45MPa hydrogen storage bottle (22) is directly applied to the 45MPa hydrogen refueling machine (31) or the 90MPa hydrogen refueling machine (30); hydrogen in the 90MPa hydrogen storage bottle (24) is directly applied to the 90MPa hydrogen refueling machine (30).

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