Liquid hydrogen refueling station cold energy recovery system and control method

Abstract

According to the liquid hydrogen refueling station cold energy recovery system and the control method, the cold energy recovery system comprises a liquid hydrogen pump and a gas hydrogen buffer tank, a cold energy recovery device is arranged between the liquid hydrogen pump and the gas hydrogen buffer tank, and the cold energy recovery device comprises at least one stage of thermoacoustic engine and at least one stage of pulse tube refrigerator; the thermoacoustic engine can recover cold energy released when liquid hydrogen flows through the thermoacoustic engine and drive the pulse tube refrigerator to conduct refrigeration. According to the cold energy recovery system, the low-temperature fluid flows through the cold energy recovery device to absorb heat and then enters the gas hydrogen buffer tank to be stored, the thermo-acoustic engine in the cold energy recovery device is driven by the cold capacity of the low-temperature fluid, meanwhile, the thermo-acoustic engine converts the cold capacity into acoustic power and then transmits the acoustic power to the pulse tube refrigerator for refrigeration, the conversion efficiency is high, and the energy consumption is low. Efficient recovery of cold energy is achieved, and cold energy lost in the temperature rising process of low-temperature fluid can be effectively recovered.

Description

Technical Field

[0001] The present invention relates to the technical field of liquid hydrogen filling, and in particular to a cold energy recovery system and a control method for a liquid hydrogen filling station. Background Art

[0002] Hydrogen energy has the advantages of being clean, safe, efficient and sustainable, and is regarded as one of the most promising clean energy sources in the 21st century. As a key supporting facility for hydrogen fuel vehicles, hydrogen refueling stations are the foundation for supporting the development of the hydrogen energy industry chain. Hydrogen refueling stations can generally be divided into high-pressure gas hydrogen refueling stations and liquid hydrogen refueling stations. The hydrogen in the high-pressure gas hydrogen refueling station is pressurized by a compressor and stored in a high-pressure hydrogen storage tank (bottle group), and the hydrogen in the liquid hydrogen refueling station is stored in a liquid hydrogen dewar in the form of low-temperature liquid hydrogen. Compared with high-pressure gas hydrogen refueling stations, liquid hydrogen refueling stations have the characteristics of high hydrogen storage density, excellent hydrogen quality, high filling efficiency and good safety, and are the main development direction.

[0003] The general process of liquid hydrogen refueling is that the liquid hydrogen in the liquid hydrogen dewar is transported to the high-pressure vaporizer through a liquid hydrogen booster pump. The liquid hydrogen absorbs the heat in the environment and naturally vaporizes in the high-pressure vaporizer, and then hydrogen is refueled through the hydrogenator. A large amount of cold energy is released during the gasification of liquid hydrogen. If this cold energy can be recycled and reused in the liquid hydrogen refueling industry chain, the cost of the liquid hydrogen refueling industry chain will be significantly reduced. Therefore, how to recycle and effectively utilize this cold energy has always been a research hotspot in the field of cold energy recovery.

[0004] CN113531388A provides a system and method for recycling cold energy in a liquid hydrogen refueling station, in which a heat exchange pipeline is arranged in parallel between a liquid hydrogen boost input pipeline and an air-temperature vaporizer; a recycling pipeline is arranged between the heat exchange pipeline and the output end; the method firstly exchanges heat between liquid hydrogen and a refrigerant, and the refrigerant with a reduced temperature enters the water tank of a chilled water unit, and the heat exchange coil cools down the refrigerant in the water tank, and after the temperature of the refrigerant is increased, it circulates back to the heat exchanger and then exchanges heat with liquid hydrogen; the cooled refrigerant is pre-cooled and cooled by the heat exchanger for the added hydrogen, and after the temperature of the refrigerant is increased by absorbing the heat of the hydrogen, it returns to the water tank for further cooling.

[0005] Chinese patent application CN115507296A provides a liquid hydrogen refueling station system for recovering BOG, in which the BOG hydrogen generated by the pre-cooling process is cooled by a five-stage segmented cooling of a first BOG recovery branch and a reliquefaction pipeline, and the BOG hydrogen from the station liquid hydrogen storage tank is cooled by a three-stage segmented cooling of a second BOG recovery branch and a reliquefaction pipeline to reliquefy the BOG, thereby achieving complete recovery and efficient storage of BOG hydrogen.

[0006] Nevertheless, when actually recovering liquid hydrogen, there is still the problem of failing to effectively recover and utilize the cold energy of liquid hydrogen gasification. Summary of the invention

[0007] The object of the present invention is to provide a cold energy recovery system for a liquid hydrogen refueling station which can effectively recover and utilize the cold energy of the liquid hydrogen refueling station.

[0008] In order to achieve the above-mentioned objectives, a first aspect of the present invention provides a cold energy recovery system, comprising a liquid hydrogen pump and a gas hydrogen buffer tank, a cold energy recovery device is arranged between the liquid hydrogen pump and the gas hydrogen buffer tank, the cold energy recovery device comprises at least one stage of thermoacoustic engine and at least one stage of pulse tube refrigerator, the thermoacoustic engine can recover the cold energy released by the liquid hydrogen flowing through the thermoacoustic engine and drive the pulse tube refrigerator for refrigeration.

[0009] Optionally, the thermoacoustic engine includes a resonance tube and a cold-end heat exchanger, a first heat regenerator and a hot-end heat exchanger connected in sequence toward the resonance tube; the resonance tube is connected to a refrigerator cylinder in the pulse tube refrigerator so that the oscillation generated by the thermoacoustic engine is transmitted to the refrigerator cylinder through the resonance tube.

[0010] Optionally, one end of the cold end heat exchanger is connected to the outlet end of the liquid hydrogen pump, and the other end is connected to the gaseous hydrogen buffer tank.

[0011] Optionally, a cold head, a pulse tube and a room temperature heat exchanger are sequentially installed in the refrigerator cylinder, and a second heat regenerator is sleeved on the outer wall of the pulse tube; the end of the cold head is connected to the output end of the room temperature heat exchanger through the second heat regenerator; the pulse tube is connected to a phase adjustment mechanism, and the phase adjustment mechanism includes compressor pistons symmetrically arranged in the refrigerator cylinder housing, and the compressor pistons are interconnected to form a compression chamber; area-difference-free dischargers and supporting leaf springs fixedly connected to the area-difference-free dischargers are symmetrically arranged in the compression chamber, an expansion chamber is formed between the area-difference-free dischargers, and the area-difference-free dischargers can reciprocate under the action of acoustic power transmitted to the refrigerator cylinder through the resonance tube.

[0012] Optionally, the cold energy recovery system further includes a liquid hydrogen storage tank, and the cold head is placed in the liquid hydrogen storage tank; or the cold end of the cold head is connected to a cold finger, and the cold finger is placed in the liquid hydrogen storage tank.

[0013] Optionally, the thermoacoustic engine is one of a standing wave type thermoacoustic engine, a traveling wave type thermoacoustic engine and a standing wave and traveling wave hybrid thermoacoustic engine; the operating temperature range of the thermoacoustic engine is 20-300K; the work output by the thermoacoustic engine is 3MJ / kgH2.

[0014] Optionally, the pulse tube refrigerator is a single-stage pulse tube refrigerator or a multi-stage pulse tube refrigerator; the no-load cooling temperature of the pulse tube refrigerator is 5-10K.

[0015] A second aspect of the present invention provides a control method for a liquid hydrogen refueling station having a cold energy recovery system, the control method comprising:

[0016] Detect the pressure of the gas hydrogen buffer tank;

[0017] When the pressure of the gas hydrogen buffer tank is greater than the preset pressure, the cold energy recovery device and the liquid hydrogen pump are turned on in sequence; the thermoacoustic engine is controlled to recover cold energy and drive the pulse tube refrigerator to work; and

[0018] When the pressure of the gas hydrogen buffer tank is less than or equal to the preset pressure, the liquid hydrogen pump is controlled to deliver hydrogen to the gas hydrogen buffer tank.

[0019] Optionally, when the hydrogen filling machine receives a filling request, the hydrogen concentration of the hydrogen filling machine and the pressure of the liquid hydrogen storage tank are detected; when the hydrogen concentration of the hydrogen filling machine and the pressure of the liquid hydrogen storage tank meet preset conditions, the pressure of the gas hydrogen buffer tank is detected.

[0020] Optionally, the mass flow rate of the liquid hydrogen pump during operation is 5-20 kg / min; and the filling rate of the hydrogenator is 3-20 kg / min.

[0021] Through the above technical scheme, the cold energy recovery system of the present invention eliminates the vaporizer conventionally used in liquid hydrogen refueling stations, and allows the low-temperature fluid to flow through the cold energy recovery device to absorb heat and then enter the gas hydrogen buffer tank for storage. The thermoacoustic engine in the cold energy recovery device is driven by the cold energy of the low-temperature fluid. At the same time, the thermoacoustic engine converts the cold energy into acoustic work and then transfers it to the pulse tube refrigerator for refrigeration. The conversion efficiency is high, and efficient recovery of cold energy is achieved, which can effectively recover the cold energy lost during the heating process of the low-temperature fluid.

[0022] Other features and advantages of the present invention will be described in detail in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the following specific embodiments, they are used to explain the present invention, but do not constitute a limitation of the present invention. In the accompanying drawings:

[0024] Figure 1 It is a schematic diagram of a cold energy recovery system for a liquid hydrogen refueling station according to an embodiment of the present invention.

[0025] Figure 2 It is a schematic structural diagram of a standing wave thermoacoustic engine according to an embodiment of the present invention.

[0026] Figure 3 It is a schematic structural diagram of a traveling wave thermoacoustic engine according to an embodiment of the present invention.

[0027] Figure 4 It is a schematic structural diagram of a pulse tube refrigerator according to an embodiment of the present invention.

[0028] Figure 5 It is a flow chart of a control method of a liquid hydrogen refueling station according to an embodiment of the present invention. DETAILED DESCRIPTION

[0029] The specific embodiments of the present invention are described in detail below. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0030] The typical form of hydrogenation at a liquid hydrogen refueling station is that the liquid hydrogen in the liquid hydrogen dewar is pressurized to a high-pressure vaporizer through a liquid hydrogen pump, and then hydrogen is refilled through a hydrogenator. The liquid hydrogen refueling process will cause a large amount of cold energy loss. Since the gas source of the liquid hydrogen refueling station is external liquid hydrogen, and liquefying gaseous hydrogen requires a large amount of energy, the inventor has therefore proposed a cold energy recovery system that can fully recycle and utilize the cold capacity of the liquid hydrogen refueling station.

[0031] In order to achieve the above object, the present invention provides a cold energy recovery system, such as Figure 1 As shown, the cold energy recovery system includes a liquid hydrogen storage tank 1, a liquid hydrogen pump 2, a gas hydrogen buffer tank 4 and a hydrogenator 5, and a cold energy recovery device is provided between the liquid hydrogen pump 2 and the gas hydrogen buffer tank 4. The cold energy recovery device includes at least one stage of thermoacoustic engine and at least one stage of pulse tube refrigerator, and the thermoacoustic engine can recover the cold energy released by the liquid hydrogen flowing through the thermoacoustic engine and drive the pulse tube refrigerator for refrigeration.

[0032] In the present invention, cryogenic liquid hydrogen is stored in a vacuum dewar having a volume of 3-10 m 3 The type of liquid hydrogen pump is immersion type, and its mass flow rate is 5-20kg / min.

[0033] Specifically, the liquid hydrogen storage tank is provided with a liquid inlet for external liquid hydrogen to enter and a gas outlet for releasing BOG.

[0034] It should be noted that insulation measures need to be taken for each pipeline and equipment in the liquid hydrogen refueling station.

[0035] The cold energy recovery system of the present invention eliminates the vaporizer conventionally used in liquid hydrogen refueling stations, and allows liquid hydrogen to flow through the cold energy recovery device to absorb heat and then enter the gas hydrogen buffer tank for storage. The thermoacoustic engine in the cold energy recovery device is driven by the cold energy of liquid hydrogen. At the same time, the thermoacoustic engine converts the cold energy into acoustic work and then transmits it to the pulse tube refrigerator for refrigeration. The conversion efficiency is high, and efficient recovery of cold energy is achieved, and the cold energy lost during the heating process of the cryogenic fluid can be effectively recovered.

[0036] The thermoacoustic effect is a physical phenomenon in which heat in a compressible medium (usually gas) generates acoustic self-oscillations caused by the interaction of sound and heat with solid media. This principle can be used to convert thermal energy into pressure fluctuations, thereby realizing the conversion of thermal energy into mechanical energy. Based on the above principle, thermoacoustic engines can also recover cold energy and realize the conversion of cold energy into mechanical energy.

[0037] According to the different sound fields, thermoacoustic engines are divided into standing wave type thermoacoustic engines, traveling wave type thermoacoustic engines and standing wave and traveling wave hybrid thermoacoustic engines. In the traveling wave sound field, the velocity wave and the pressure wave have the same phase, while in the standing wave sound field, the two are 90° out of phase.

[0038] In the present invention, the thermoacoustic engine is one of a standing wave type thermoacoustic engine, a traveling wave type thermoacoustic engine and a standing wave and traveling wave hybrid thermoacoustic engine.

[0039] When using different types of thermoacoustic engines, the shape of the resonance tube also needs to match the thermoacoustic engine. For example, when using a traveling wave thermoacoustic engine, the resonance tube is annular; when using a standing wave thermoacoustic engine, the resonance tube is straight.

[0040] Figure 2 A typical standing wave thermoacoustic engine is schematically shown as Figure 2 As shown, the thermoacoustic engine 3 includes a resonance tube 311 and a cold end heat exchanger 312, a first regenerator 313 and a hot end heat exchanger 314 connected in sequence toward the resonance tube 311; one end of the cold end heat exchanger 312 is connected to the outlet end of the liquid hydrogen pump, and the other end is connected to the gas hydrogen buffer tank, the hot end heat exchanger 314 is placed in a room temperature environment, and the side wall of the hot end heat exchanger 314 is connected to the resonance tube 311. The resonance tube 311 is connected to the refrigerator cylinder in the pulse tube refrigerator, so that the oscillation generated by the thermoacoustic engine 3 is transmitted to the refrigerator cylinder through the resonance tube 311.

[0041] The thermoacoustic engine can also be a traveling wave type thermoacoustic engine, such as Figure 3 As shown in Figure 2 On the basis of the heat buffer tube 325 and the secondary hot end heat exchanger 326, the first cold section heat exchanger 322 is connected to the heat buffer tube 325 on one side different from the first regenerator 323, and is connected to the secondary hot end heat exchanger 326 through the heat buffer tube 325. The other side of the secondary hot end heat exchanger 326 is connected to the hot end heat exchanger 324 and the pulse tube refrigerator through the annular resonance tube 321. In addition, the thermoacoustic engine can also adopt a combination of standing waves and traveling waves, which will not be described one by one here.

[0042] In a specific embodiment of the present invention, the cold end heat exchanger of the thermoacoustic engine is connected to the outlet end of the liquid hydrogen pump, and the hot end heat exchanger is placed in the environment and can output about 3MJ / kgH2. The cryogenic fluid is introduced into the cold end heat exchanger, and the total latent heat (sensible heat and latent heat) of the cryogenic fluid is used to provide cooling for the cold end heat exchanger. Under the temperature gradient of the hot end heat exchanger and the cold end heat exchanger, the gas medium in the first regenerator oscillates along the thermoacoustic plate stack in the first regenerator, and the generated oscillation is transmitted to the working gas in the refrigerator cylinder through the resonance tube. The resonance tube is directly connected to the refrigerator cylinder to transfer the acoustic power generated by the thermoacoustic engine to the working gas, and refrigeration is achieved by the reciprocating oscillation of the working gas in the refrigerator cylinder.

[0043] like Figure 4 As shown, a cold head 61, a pulse tube 62 and a room temperature heat exchanger 63 are sequentially installed in the refrigerator cylinder of the pulse tube refrigerator 6, a second heat regenerator 64 is sleeved on the outer wall of the pulse tube 62, and the inner top surface of the cold head 61 is tightly connected to the pulse tube 62. The end of the cold head 61 is connected to the output end of the room temperature heat exchanger 63 through the second heat regenerator 64.

[0044] The input end of the room temperature heat exchanger 63 is connected to a phase adjustment structure, which includes compressor pistons 66 symmetrically arranged in the compressor housing of the pulse tube refrigerator. The cavities between the compressor pistons 66 are interconnected to form a compression cavity 65.

[0045] A symmetrically arranged area-free displacer 67 and a support leaf spring 68 fixedly connected to the area-free displacer 67 are provided in the compression chamber 65. One end of the support leaf spring 68 abuts against the top surface of the compression chamber 65, and the other end abuts against the bottom surface of the compression chamber 65. There is a gap seal between the area-free displacer 67 and the top and bottom surfaces of the compression chamber 65, which is used to isolate the fluid flow on both sides of the compressor piston 66. The area-free displacer 67 has the same cross section and is symmetrically arranged, dividing the compression chamber 65 into two compression chambers, and an expansion chamber 69 is formed between the two symmetrically arranged area-free displacers 67. The area-free displacer 67 can reciprocate under the drive of pressure fluctuations, and a channel connected to the room temperature heat exchanger 63 is formed between the compressor piston 66 and the shell. The area-free displacer 67 forms a pressure fluctuation at the hot end of the pulse tube 62, and the acoustic work generated by the pressure fluctuation is transferred to the compression chamber 65 by the room temperature heat exchanger 63 for recovery.

[0046] The pulse tube can reduce the heat exchange between the cold head and the room temperature and transfer acoustic power. Specifically, a pulse tube heat exchanger is also provided at one end of the pulse tube 62 close to the compression chamber 65 .

[0047] The working gas in the refrigerator compressor cylinder performs reciprocating oscillation motion in the cold head 61, the second regenerator 64, the room temperature heat exchanger 63 and the pulse tube 62. When the working gas reciprocates, the heat on the room temperature heat exchanger 63 is pumped to the cold head, and then discharged out of the system through the room temperature heat exchanger, thereby finally achieving refrigeration.

[0048] Specifically, the compressor piston 66 is symmetrically arranged, and its movement directions are opposite and the vibrations generated cancel each other out. The acoustic work generated by the thermoacoustic engine is transferred to the gas in the compression chamber and drives the compressor piston to reciprocate, thereby generating periodic pressure waves. The working fluid gas (generally helium) in the expansion chamber generates a refrigeration effect in the second regenerator after expansion, and at the same time, the heat of the cold head is transported to the room temperature heat exchanger, thereby generating cold energy at the cold head.

[0049] Preferably, after appropriate frequency matching, the frequencies of the thermoacoustic engine and the pulse tube refrigerator are the same to enhance the oscillation of the working gas in the refrigerator cylinder.

[0050] In a specific embodiment of the present invention, the no-load cooling temperature of the pulse tube refrigerator is 5-10K, and the operating temperature range of the thermoacoustic engine is 20-300K.

[0051] In a preferred embodiment of the present invention, in order to effectively utilize the cold recovered by the thermoacoustic engine, the cold head is placed in the liquid hydrogen storage tank; or a section of the cold head is connected to a cold finger, and the cold finger is placed in the liquid hydrogen storage tank.

[0052] In a specific embodiment of the present invention, the cold energy in the cold head is transferred to the cold finger, which in turn cools the evaporated hydrogen in the liquid hydrogen storage tank. In addition, the cold head can also be directly placed in the liquid hydrogen storage tank to convert the evaporated hydrogen into liquid hydrogen.

[0053] The cold fingers or cold heads placed in the liquid hydrogen storage tanks can further cool the evaporated hydrogen in the liquid hydrogen storage tanks, turning it into liquid hydrogen, which not only saves the energy consumed in liquefying the gaseous hydrogen, but also can use the energy generated by the recovered cold for the liquid hydrogen refueling system, reducing the energy consumption of the entire industrial chain and thereby reducing the cost of liquid hydrogen refueling stations.

[0054] For example, from an economic perspective, the energy consumption of hydrogen liquefaction is 14kWh / kg. By adopting the cold energy recovery system of the present invention and using the pulse tube refrigerator to liquefy gaseous hydrogen, a 4000kg / d liquid hydrogen refueling station can increase its income by 2000 yuan / d. There is a certain degree of hydrogen evaporation and leakage in the liquid hydrogen storage tank. The recovered cold energy is used for gaseous hydrogen liquefaction, which not only reduces hydrogen evaporation and leakage, but also effectively utilizes the recovered cold energy, effectively reducing the cost of the industrial chain.

[0055] Based on the cold energy recovery system of the liquid hydrogen refueling station proposed in this embodiment, assuming that all devices in the system are in a closed or stopped state, the specific implementation steps include the following:

[0056] Open the shut-off valve, and the liquid hydrogen in the liquid hydrogen storage tank enters the cold energy recovery device through the liquid hydrogen pump, flows through the cold end heat exchanger of the thermoacoustic engine to complete the gasification of the liquid hydrogen, and the cold energy is converted into acoustic power through the gas medium in the thermoacoustic engine and transferred to the working gas in the pulse tube refrigerator for recycling. The gasified liquid hydrogen enters the gas hydrogen buffer tank through the conduit and is used for high-pressure hydrogen filling of the hydrogen filling machine.

[0057] The present invention also provides a control method for a liquid hydrogen refueling station having a cold energy recovery system, the control method comprising:

[0058] Detect the pressure of the gas hydrogen buffer tank;

[0059] When the pressure of the gas hydrogen buffer tank is greater than the preset pressure, the cold energy recovery device and the liquid hydrogen pump are turned on in sequence;

[0060] Controlling the thermoacoustic engine to recover cold energy and drive the pulse tube refrigerator; and

[0061] When the pressure of the gas hydrogen buffer tank is less than or equal to the preset pressure, the liquid hydrogen pump is controlled to deliver hydrogen to the gas hydrogen buffer tank.

[0062] When the hydrogen filling machine receives a filling request, the hydrogen concentration of the hydrogen filling machine and the pressure of the liquid hydrogen storage tank are detected; when the hydrogen concentration of the hydrogen filling machine and the pressure of the liquid hydrogen storage tank meet the preset conditions, the pressure of the gas hydrogen buffer tank is detected.

[0063] Figure 5 FIG. 1 is a flow chart of a control method for a liquid hydrogen refueling station according to an embodiment of the present invention. Figure 5 As shown, the method uses a liquid hydrogen storage tank, a liquid hydrogen pump, a cold energy recovery device (including a thermoacoustic engine and a pulse tube refrigerator), a gas hydrogen buffer tube and a hydrogenator, and the method includes:

[0064] Step 11, detecting the hydrogen concentration of the hydrogenator and the pressure of the liquid hydrogen storage tank;

[0065] Step 12, detecting the pressure of the gas hydrogen buffer tank;

[0066] Step 13, determining whether the pressure of the gas hydrogen buffer tank is equal to a preset pressure;

[0067] Step 14, when the pressure of the gas hydrogen buffer tank is greater than the preset pressure, the cold energy recovery device and the liquid hydrogen pump are turned on in sequence; the thermoacoustic engine is controlled to recover cold energy and drive the pulse tube refrigerator to work;

[0068] Step 15, when the pressure of the gas hydrogen buffer tank is less than or equal to the preset pressure, starting the liquid hydrogen pump and controlling the liquid hydrogen pump to transport hydrogen to the gas hydrogen buffer tank;

[0069] Step 16, start the hydrogen filling system.

[0070] The liquid hydrogen refueling station of the present invention has the above-mentioned cold energy recovery system. When the hydrogenator receives a refueling signal, it is necessary to first detect whether the hydrogen concentration of the hydrogenator and the pressure of the liquid hydrogen storage tank meet the hydrogenation requirements. If the requirements are met, the pressure of the gas hydrogen buffer tank is detected. If the pressure of the gas hydrogen buffer tank is higher than 35MPa, the cold energy recovery device and the liquid hydrogen pump can be started in sequence. The liquid hydrogen absorbs heat through the cold energy recovery device and is input into the gas hydrogen buffer tank. While the hydrogenator is refueling, the thermoacoustic engine and the pulse tube refrigerator recover and utilize the cold energy lost by the liquid hydrogen. If the pressure of the gas hydrogen buffer tank is less than or equal to 35MPa, the liquid hydrogen pump can be started first to meet the refueling needs of the hydrogenator.

[0071] Wherein, the mass flow rate of the liquid hydrogen pump when working is 5-20kg / min; the filling rate of the hydrogen filling machine is 3-20kg / min.

[0072] The cyclic operation of the cold energy recovery system of the present invention is based on the normal use of the hydrogenator. When the hydrogenator is continuously used, the liquid hydrogen pump continuously transports the liquid hydrogen in the liquid hydrogen storage tank to flow through the thermoacoustic engine, so that the thermoacoustic engine uses the cold energy of the liquid hydrogen flowing through the cold end heat exchanger for recovery and utilization.

[0073] Take a liquid hydrogen refueling station equipped with a 35MPa liquid hydrogen refueling machine as an example. The main parameters of the liquid hydrogen refueling machine are as follows:

[0074] The filling flow rate is 8-20kg / min, the rated working pressure is 35MPa, the maximum working pressure is 43.8MPa, the maximum design pressure is 48.7MPa, the filling pressure is 0.5-20MPa, and the filling temperature is -40℃ to 50℃.

[0075] The overall process of this scheme is as follows: when the hydrogen filling machine receives the hydrogen filling signal, it first detects whether the hydrogen concentration of the hydrogen filling machine and the pressure in the liquid hydrogen storage tank meet the hydrogen filling requirements. If the hydrogen filling requirements are met, the pressure of the gas hydrogen buffer tank is detected. If the pressure of the gas hydrogen buffer tank is higher than 35MPa, the cold energy recovery device and the liquid hydrogen pump are started in sequence. Turn on the liquid hydrogen pump, pressurize the liquid hydrogen in the liquid hydrogen storage tank to about 2MPa, and then transport it to the cold end heat exchanger of the thermoacoustic engine to exchange heat with the low-temperature liquid hydrogen to recover the cold in the low-temperature liquid hydrogen. The rate of liquid hydrogen flowing through the cold end heat exchanger is 8-20kg / min. After heat exchange, the liquid hydrogen vaporizes and heats up to about -40°C, then enters the gas hydrogen buffer tank, and is then transported to the hydrogen filling machine for external filling.

[0076] The temperature of the gas medium in the cold end heat exchanger entering the cold end heat exchanger is controlled at about -250°C, and the temperature out of the cold end heat exchanger is controlled at about -40°C. The gas medium in the first regenerator oscillates along the thermoacoustic plate stack in the first regenerator, and the generated oscillation is transmitted to the working gas in the refrigerator cylinder through the resonance tube. The working gas oscillates back and forth in the refrigerator cylinder to realize the refrigeration of the pulse tube refrigerator. The no-load refrigeration temperature of the pulse tube refrigerator is 10K.

[0077] In the cold energy recovery system provided in this embodiment, the second cold end heat exchanger of the pulse tube refrigerator is placed in the liquid hydrogen storage tank, which can be used to liquefy the vaporized hydrogen in the liquid hydrogen storage tank. It should be noted that placing the cold head of the pulse tube refrigerator or the cold finger connected to the cold head in liquid hydrogen can maintain the temperature of the liquid hydrogen or re-condense the BOG to reduce the evaporation loss of hydrogen. If the pressure of the gas hydrogen buffer tank is less than 35MPa, only the liquid hydrogen pump is turned on to pressurize the liquid hydrogen in the liquid hydrogen storage tank to about 2MPa and then flow through the cold end heat exchanger to exchange heat with the low-temperature liquid hydrogen. The rate at which liquid hydrogen passes through the cold end heat exchanger is 8-20kg / min.

[0078] For a liquid hydrogen refueling station with a hydrogenation rate of 14 kg / min, if calculated based on a hydrogenation amount of 1000 kg / 12 hr per day, the power consumption saved by the system of the present invention for liquefying hydrogen volatilized in the liquid hydrogen storage tank is equivalent to 2000 KWh / d.

[0079] Statistics show that the hydrogen mass loss rate of liquid hydrogen refueling stations decreased by approximately 20% to 50% within one month of operating the above system, greatly reducing hydrogen loss and improving the economic benefits of hydrogen refueling station operations.

[0080] The present invention also provides a method for recycling cold energy of a liquid hydrogen refueling station, which specifically comprises the following steps:

[0081] When the hydrogenation machine receives the hydrogenation signal, it first detects whether the hydrogen concentration of the hydrogenation machine and the pressure in the liquid hydrogen storage tank meet the hydrogenation requirements. If the hydrogenation requirements are met, the pressure of the gas hydrogen buffer tank is detected. If the pressure of the gas hydrogen buffer tank is higher than 35MPa, the cold energy recovery device and the liquid hydrogen pump are started in sequence. Turn on the liquid hydrogen pump, pressurize the liquid hydrogen in the liquid hydrogen storage tank to 35MPa, and then transport it to the cold end heat exchanger of the thermoacoustic engine to exchange heat with the low-temperature liquid hydrogen to recover the cold in the low-temperature liquid hydrogen. The rate of liquid hydrogen flowing through the cold end heat exchanger is 8-20kg / min. After heat exchange, the liquid hydrogen vaporizes and heats up to about -20°C, then enters the gas hydrogen buffer tank, and is then transported to the hydrogenation machine for external filling.

[0082] If the pressure of the gas hydrogen buffer tank is less than 35MPa, only the liquid hydrogen pump is turned on to pressurize the liquid hydrogen in the liquid hydrogen storage tank to 35MPa and then flow through the cold end heat exchanger to exchange heat with the low-temperature liquid hydrogen. The rate of liquid hydrogen passing through the cold end heat exchanger is 8-20kg / min.

[0083] The preferred embodiments of the present invention are described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, a variety of simple modifications can be made to the technical solution of the present invention, and these simple modifications all belong to the protection scope of the present invention.

[0084] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations.

[0085] In addition, various embodiments of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the present invention, they should also be regarded as the contents disclosed by the present invention.

Claims

1. A cold energy recovery system, comprising a liquid hydrogen pump and a gas hydrogen buffer tank, characterized in that: A cold energy recovery device is provided between the liquid hydrogen pump and the gaseous hydrogen buffer tank, and the cold energy recovery device includes at least one stage of thermoacoustic engine and at least one stage of pulse tube refrigerator. The thermoacoustic engine can recover the cold energy released by the liquid hydrogen flowing through the thermoacoustic engine and drive the pulse tube refrigerator for refrigeration.

2. The cold energy recovery system according to claim 1, wherein: The thermoacoustic engine comprises a resonance tube, and a cold end heat exchanger, a first heat regenerator and a hot end heat exchanger connected in sequence toward the resonance tube; The resonance tube is connected to a refrigerator cylinder in the pulse tube refrigerator, so that the oscillation generated by the thermoacoustic engine is transmitted to the refrigerator cylinder through the resonance tube.

3. The cold energy recovery system according to claim 2, wherein: One end of the cold end heat exchanger is connected to the outlet end of the liquid hydrogen pump, and the other end is connected to the gas hydrogen buffer tank.

4. The cold energy recovery system according to claim 2, wherein: A cold head, a pulse tube and a room temperature heat exchanger are sequentially installed in the refrigerator cylinder, and a second heat regenerator is sleeved on the outer wall of the pulse tube; the end of the cold head is connected to the output end of the room temperature heat exchanger through the second heat regenerator; The pulse tube is connected to a phase-adjusting structure, which includes compressor pistons symmetrically arranged in the cylinder housing of the refrigerator, and the compressor pistons are interconnected to form a compression chamber; area-difference-free displacers and supporting leaf springs fixedly connected to the area-difference-free displacers are symmetrically arranged in the compression chamber, and an expansion chamber is formed between the area-difference-free displacers, and the area-difference-free displacers can reciprocate under the action of acoustic power transmitted to the refrigerator cylinder through the resonance tube.

5. The cold energy recovery system according to claim 4, wherein: The cold energy recovery system further includes a liquid hydrogen storage tank, in which the cold head is placed; or a cold end of the cold head is connected to a cold finger, which is placed in the liquid hydrogen storage tank.

6. The cold energy recovery system according to claim 1, wherein: The thermoacoustic engine is one of a standing wave type thermoacoustic engine, a traveling wave type thermoacoustic engine and a standing wave and traveling wave hybrid type thermoacoustic engine; The operating temperature range of the thermoacoustic engine is 20-300K; The work output by the thermoacoustic engine is 3-3.5 MJ / kgH2.

7. The cold energy recovery system according to claim 1, wherein: The pulse tube refrigerator is a single-stage pulse tube refrigerator or a multi-stage pulse tube refrigerator; The no-load cooling temperature of the pulse tube refrigerator is 5-10K.

8. A control method for a liquid hydrogen refueling station with a cold energy recovery system, characterized in that: The control method comprises: Detect the pressure of the gas hydrogen buffer tank; When the pressure of the gas hydrogen buffer tank is greater than the preset pressure, the cold energy recovery device and the liquid hydrogen pump are turned on in sequence; the thermoacoustic engine is controlled to recover cold energy and drive the pulse tube refrigerator to work; and When the pressure of the gas hydrogen buffer tank is less than or equal to the preset pressure, the liquid hydrogen pump is controlled to deliver hydrogen to the gas hydrogen buffer tank.

9. The control method according to claim 8, wherein: When the hydrogen filling machine receives a filling request, the hydrogen concentration of the hydrogen filling machine and the pressure of the liquid hydrogen storage tank are detected; When the hydrogen concentration of the hydrogenator and the pressure of the liquid hydrogen storage tank meet the preset conditions, the pressure of the gas hydrogen buffer tank is detected.

10. The control method according to claim 8, wherein: The mass flow rate of the liquid hydrogen pump when working is 5-20kg / min; The filling rate of the hydrogenator is 3-20 kg / min.

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