A hydrogen liquefaction apparatus and subcritical cryogenic ejector therefor

Abstract

The application provides a hydrogen liquefaction device and a subcritical low-temperature ejector used in the hydrogen liquefaction device, the subcritical low-temperature ejector has an ejector flow channel inside, the ejector flow channel comprises a high-pressure inlet section, a high-pressure nozzle section, a low-pressure ejector section, a mixing section and a diffusion section; wherein the inlet of the high-pressure inlet section has a first cross-sectional area, the outlet of the high-pressure nozzle section has a second cross-sectional area, and the outlet of the diffusion section has a third cross-sectional area; the ratio S1 between the first cross-sectional area and the second cross-sectional area satisfies the following formula: 7.5 < S1 < 15; and the ratio S2 between the first cross-sectional area and the third cross-sectional area satisfies the following formula: 0.5 < S2 < 0.8. The application controls the ratio between the first cross-sectional area of the high-pressure inlet section and the second cross-sectional area of the high-pressure nozzle section and the ratio between the first cross-sectional area of the high-pressure inlet section and the third cross-sectional area of the diffusion section within a reasonable range by reasonably optimizing the ejector flow channel of the subcritical low-temperature ejector, so that the clogging situation is avoided.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of hydrogen energy utilization equipment, in particular to a hydrogen liquefaction device and a subcritical low-temperature ejector therefor. BACKGROUND

[0002] Hydrogen energy, as a "zero-carbon" clean energy, has the characteristics of abundant reserves, renewable, clean and efficient, etc., and only emits water during use without emitting other harmful gases or solid particles. Its development and utilization are the inevitable trend of future energy development. Liquid hydrogen, due to its high hydrogen carrying density, low storage and transportation pressure, high gasification purity, and cost advantage, has become a hydrogen energy product form that countries are competing to develop. After the terminal application of the civil hydrogen energy industry breaks out, it reversely promotes the development demand of large-scale and low-energy consumption technology for liquid hydrogen plants. For large-scale liquid hydrogen plants, a small increase in efficiency has a huge impact on the economy of the entire system.

[0003] In the production process of large-scale hydrogen liquefaction equipment, a hydrogen turbine expansion refrigeration cycle process is generally used, and the final stage is cooled to the liquid hydrogen temperature zone by relying on the throttling of a low-temperature hydrogen throttle valve. In the liquid hydrogen production process, after the throttling of the final stage hydrogen, the low-temperature hydrogen cannot be completely liquefied, and a large amount of gaseous hydrogen will be produced. This part of hydrogen flows into the liquid hydrogen storage tank together with the liquid hydrogen, which on the one hand reduces the liquefaction rate of hydrogen in the hydrogen liquefaction equipment, and on the other hand continuously increases the pressure in the liquid hydrogen storage tank. In actual hydrogen liquefaction production, in order to ensure the safety of the storage tank, when the pressure reaches the set upper limit, the low-temperature hydrogen in the tank needs to be vented, which will greatly reduce the liquid hydrogen production and the utilization rate of liquid hydrogen.

[0004] In some hydrogen liquefaction equipment, a hydrogen ejector is provided to realize the recooling and liquefaction of the evaporated liquid hydrogen in the storage tank. Specifically, a high-pressure working fluid flows into the hydrogen ejector to realize expansion and pressure reduction, and becomes a high-speed low-pressure fluid, which then introduces the hydrogen vapor at the suction end of the hydrogen ejector into the suction chamber of the hydrogen ejector. This part of hydrogen vapor is the evaporation amount caused by the conversion of ortho-hydrogen and para-hydrogen in the liquid hydrogen storage tank. The hydrogen vapor at the suction end leaves the hydrogen ejector after passing through the mixing chamber and the diffusion chamber, and flows into the heat exchanger for heat exchange and cooling to realize liquefaction again. This process can effectively utilize the cold energy and avoid the flow of evaporated hydrogen back to the compressor, thereby reducing the loss of cold energy in the process.

[0005] However, when the high-pressure working fluid is in a subcritical state, the conventional hydrogen ejector will be blocked, affecting the normal operation of the hydrogen liquefaction equipment.

[0006] Therefore, the present application is proposed. SUMMARY

[0007] The technical problem solved by the present application is to at least overcome some of the deficiencies of the prior art, and provide a subcritical cryogenic ejector for a hydrogen liquefaction device, which aims to control the ratio between the first cross-sectional area of the high-pressure inlet section and the second cross-sectional area of the high-pressure nozzle section and the ratio between the first cross-sectional area of the high-pressure inlet section and the third cross-sectional area of the diffusion section within a reasonable range by reasonably optimizing the ejector flow passage of the subcritical cryogenic ejector, so as to avoid the blockage of the subcritical cryogenic ejector.

[0008] To solve the above technical problems, the basic idea of the technical solution of the present application is:

[0009] A subcritical cryogenic ejector for a hydrogen liquefaction device, the subcritical cryogenic ejector has an ejector flow passage inside, the ejector flow passage includes a high-pressure inlet section, a high-pressure nozzle section, a low-pressure ejector section, a mixing section and a diffusion section;

[0010] The inlet of the high-pressure inlet section has a first cross-sectional area, the outlet of the high-pressure nozzle section has a second cross-sectional area, and the outlet of the diffusion section has a third cross-sectional area.

[0011] The ratio S1 between the first cross-sectional area and the second cross-sectional area satisfies the following formula:

[0012] 7.5 < S1 < 15;

[0013] The ratio S2 between the first cross-sectional area and the third cross-sectional area satisfies the following formula:

[0014] 0.5 < S2 < 0.8.

[0015] In some embodiments, the subcritical cryogenic ejector comprises:

[0016] An outer shell, a side wall of the outer shell is provided with an ejector gas inlet;

[0017] A high-pressure inner shell, the high-pressure inlet section and the high-pressure nozzle section are sequentially formed in the high-pressure inner shell, the high-pressure inner shell is arranged in the outer shell, and a first end of the high-pressure inner shell is arranged in a conical structure, the first end of the high-pressure inner shell is located downstream of the ejector gas inlet;

[0018] A medium-pressure inner shell, the mixing section and the diffusion section are sequentially formed in the medium-pressure inner shell, the medium-pressure inner shell is arranged in the outer shell, and a first end of the medium-pressure inner shell is arranged in a conical cylinder structure, the first end of the medium-pressure inner shell is located downstream of the first end of the high-pressure inner shell, and the first end of the medium-pressure inner shell and the first end of the high-pressure inner shell form the low-pressure ejector section in communication with the ejector gas inlet.

[0019] In some embodiments, a measurement guide pipe flow channel is formed on the side wall of the medium-pressure inner shell corresponding to the position of the mixing section and / or the diffusion section, for measuring the pressure of the mixing section and / or the diffusion section.

[0020] The outer shell body is provided with a measurement interface corresponding to the measurement guide pipe flow channel.

[0021] In some embodiments, the inner diameter of the outer shell body corresponding to the high-pressure inner shell is smaller than the inner diameter of the outer shell body corresponding to the medium-pressure inner shell.

[0022] In some embodiments, the second end of the high-pressure inner shell is welded to the end of the outer shell body, and the second end of the medium-pressure inner shell is welded to the end of the outer shell body.

[0023] In some embodiments, the high-pressure inner shell and the medium-pressure inner shell are interference-fitted with the outer shell body.

[0024] In some embodiments, the high-pressure inner shell comprises a first high-pressure inner half shell and a second high-pressure inner half shell connected by axial snap-welding, and the first high-pressure inner half shell and the second high-pressure inner half shell are mirror-symmetrically structured.

[0025] In some embodiments, the medium-pressure inner shell comprises a first medium-pressure inner half shell and a second medium-pressure inner half shell connected by axial snap-welding, and the first medium-pressure inner half shell and the second medium-pressure inner half shell are mirror-symmetrically structured.

[0026] The measurement guide pipe flow channel is arranged on the first medium-pressure inner half shell and / or the second medium-pressure inner half shell.

[0027] The present application also provides a hydrogen liquefaction device, comprising:

[0028] a plurality of stages of heat exchangers; and

[0029] According to the above-mentioned subcritical cryogenic ejector for a hydrogen liquefaction device, the subcritical cryogenic ejector is arranged between any two stages of heat exchangers.

[0030] In some embodiments, the subcritical cryogenic ejector is arranged between the last-but-one stage of heat exchangers and the last-but-two stage of heat exchangers.

[0031] After the above technical solutions are adopted, the present application has the following beneficial effects compared with the prior art.

[0032] 1. The subcritical low-temperature ejector for the hydrogen liquefaction equipment provided by the present application controls the ratio between the first cross-sectional area of the high-pressure inlet section and the second cross-sectional area of the high-pressure nozzle section and the ratio between the first cross-sectional area of the high-pressure inlet section and the third cross-sectional area of the diffusion section within a reasonable range by reasonably optimizing the flow channel of the subcritical low-temperature ejector, thereby avoiding the clogging of the subcritical low-temperature ejector.

[0033] 2. The subcritical low-temperature ejector for the hydrogen liquefaction equipment provided by the present application measures the gas pressure of the mixing section and / or the diffusion section by opening a measuring guide channel on the sidewall of the medium-pressure inner shell at the position corresponding to the mixing section and / or the diffusion section, thereby enabling the working state of the subcritical low-temperature ejector to be analyzed in real time using the gas pressure to ensure that the hydrogen can be 100% liquefied.

[0034] 3. The subcritical low-temperature ejector for the hydrogen liquefaction equipment provided by the present application can control the dimensional tolerance of the split components before the high-pressure inner shell and the medium-pressure inner shell are buckled and welded, thereby avoiding the deformation problem caused by thermal stress in the integral casting and further ensuring that the ratio between the first cross-sectional area of the high-pressure inlet section and the second cross-sectional area of the high-pressure nozzle section and the ratio between the first cross-sectional area of the high-pressure inlet section and the third cross-sectional area of the diffusion section are controlled within a reasonable range.

[0035] 4. The hydrogen liquefaction equipment provided by the present application can effectively utilize the small temperature difference between the high-pressure stream and the low-pressure stream by arranging the subcritical low-temperature ejector between the penultimate stage and the antepenultimate stage heat exchanger, thereby achieving easy mixing, and the energy and temperature lost after mixing are low, and the hydrogen can be 100% re-liquefied into liquid hydrogen by cooperating with the throttling pressure reduction of the throttle valve, thereby more effectively improving the hydrogen liquefaction rate of the hydrogen liquefaction equipment.

[0036] The specific embodiments of the present application will be described in further detail below with reference to the accompanying drawings. BRIEF DESCRIPTION OF DRAWINGS

[0037] The accompanying drawings are part of the present application and serve to provide a further understanding of the present application, and the schematic embodiments of the present application and the descriptions thereof serve to explain the present application but do not constitute an improper limitation on the present application. Obviously, the accompanying drawings in the following description are only some embodiments, and other drawings can be obtained by those skilled in the art without any creative effort. In the drawings:

[0038] Figure 1 is a structural schematic view of the subcritical low-temperature ejector for the hydrogen liquefaction equipment provided according to the exemplary embodiments of the present application;

[0039] Figure 2is a structural schematic diagram of an outer casing provided according to an exemplary embodiment of the present application;

[0040] Figure 3 is a structural schematic diagram of a high-pressure inner casing provided according to an exemplary embodiment of the present application;

[0041] Figure 4 is a structural schematic diagram of a medium-pressure inner casing provided according to an exemplary embodiment of the present application.

[0042] In the figure: 100, subcritical low-temperature ejector;

[0043] 10, outer casing; 11, ejector gas inlet; 12, low-pressure inlet connector; 13, measurement interface; 14, measurement connector; 15, low-pressure ejector section;

[0044] 20, high-pressure inner casing; 21, high-pressure inlet section; 22, high-pressure nozzle section; 23, conical structure; 24, high-pressure inlet connector; 25, first high-pressure inner half casing; 26, second high-pressure inner half casing;

[0045] 30, medium-pressure inner casing; 31, mixing section; 32, diffusion section; 33, discharge section; 34, conical cylinder structure; 35, medium-pressure outlet connector; 36, measurement guide tube flow channel; 37, first medium-pressure inner half casing; 38, second medium-pressure inner half casing.

[0046] It should be noted that the drawings and the written description are not intended to limit the scope of the present application in any way, but are merely to illustrate the concept of the present application to those skilled in the art by referring to specific embodiments. DETAILED DESCRIPTION

[0047] In order to make the purpose, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments will be described clearly and completely below with reference to the drawings in the embodiments of the present application. The following embodiments are used to illustrate the present application, but are not used to limit the scope of the present application.

[0048] In the description of the present application, it should be noted that the terms "upper", "lower", "front", "back", "left", "right", "vertical", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application.

[0049] In the description of the present application, it should be noted that unless specifically defined and limited otherwise, the terms "mounting", "connection", "linking" should be understood in a broad sense, for example, it can be fixed connection, or detachable connection, or integral connection, it can be mechanical connection, or electrical connection, it can be direct connection, or indirect connection through intermediate medium. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0050] As described previously, when the high-pressure working fluid of the hydrogen ejector in the hydrogen liquefying device is in a subcritical state, it will cause the conventional hydrogen ejector to be blocked, affecting the normal operation of the hydrogen liquefying device. Based on this, the present application provides a subcritical low-temperature ejector for a hydrogen liquefying device, which has an ejecting flow channel inside, the ejecting flow channel including a high-pressure inlet section, a high-pressure nozzle section, a low-pressure ejecting section, a mixing section and a diffusion section; wherein the inlet of the high-pressure inlet section has a first cross-sectional area, the outlet of the high-pressure nozzle section has a second cross-sectional area, and the outlet of the diffusion section has a third cross-sectional area; the ratio S1 between the first cross-sectional area and the second cross-sectional area satisfies the following formula: 7.5 < S1 < 15; the ratio S2 between the first cross-sectional area and the third cross-sectional area satisfies the following formula: 0.5 < S2 < 0.8. In the above scheme, by reasonably optimizing the ejecting flow channel of the subcritical low-temperature ejector, the ratio between the first cross-sectional area of the high-pressure inlet section and the second cross-sectional area of the high-pressure nozzle section and the ratio between the first cross-sectional area of the high-pressure inlet section and the third cross-sectional area of the diffusion section are both controlled within a reasonable range, avoiding the situation that the subcritical low-temperature ejector is blocked.

[0051] The preferred technical scheme of the hydrogen liquefying device and the subcritical low-temperature ejector 100 provided by the present application will be described below with reference to the accompanying drawings.

[0052] Figure 1 is a structure schematic diagram of the subcritical low-temperature ejector 100 for a hydrogen liquefying device provided according to an exemplary embodiment of the present application; Figure 2 is a structure schematic diagram of the outer shell 10 provided according to an exemplary embodiment of the present application; Figure 3 is a structure schematic diagram of the high-pressure inner shell 20 provided according to an exemplary embodiment of the present application; Figure 4 is a structure schematic diagram of the medium-pressure inner shell 30 provided according to an exemplary embodiment of the present application.

[0053] As Figures 1 to 4As shown, the subcritical low-temperature ejector 100 comprises an outer shell 10, a high-pressure inner shell 20 and a medium-pressure inner shell 30. The outer shell 10 has a side wall with an ejecting gas inlet 11 formed therein, and a low-pressure inlet connecting pipe 12 can be welded to the ejecting gas inlet 11. The high-pressure inlet section 21 and the high-pressure nozzle section 22 are formed in the high-pressure inner shell 20 in sequence, the high-pressure inner shell 20 is arranged in the outer shell 10, and the first end of the high-pressure inner shell 20 is arranged in a conical structure 23, the first end of the high-pressure inner shell 20 (the outlet of the high-pressure nozzle section 22) is located downstream of the ejecting gas inlet 11. The mixing section 31 and the diffusion section 32 are formed in the medium-pressure inner shell 30 in sequence, the medium-pressure inner shell 30 is arranged in the outer shell 10, and the first end of the medium-pressure inner shell 30 (the inlet of the mixing section 31) is arranged in a conical cylinder structure 34, the first end of the medium-pressure inner shell 30 is located downstream of the first end of the high-pressure inner shell 20, and a low-pressure ejecting section 15 is formed between the first end of the high-pressure inner shell 20 and the first end of the medium-pressure inner shell 30, and the low-pressure ejecting section 15 is in communication with the ejecting gas inlet 11. In other words, the low-pressure ejecting section 15 is a conical annular gap with a certain thickness formed between the first end of the high-pressure inner shell 20 and the first end of the medium-pressure inner shell 30.

[0054] Further, the high-pressure inlet connecting pipe 24 is welded to the high-pressure inlet section 21, and the medium-pressure inner shell 30 is further provided with a discharge section 33 downstream of the diffusion section 32, and the discharge section 33 is welded with a medium-pressure outlet connecting pipe 35.

[0055] In actual operation, the low-temperature hydrogen gas in the hydrogen liquefaction device that has not yet been reduced to the liquid hydrogen temperature zone is used as a high-pressure gas source, enters the high-pressure inlet section 21 of the subcritical low-temperature ejector 100 from the high-pressure inlet connecting pipe 24, then is adiabatically expanded through the high-pressure nozzle section 22, converts pressure into kinetic energy, increases flow rate but reduces pressure, forms a low-pressure area in the mixing section 31 of the medium-pressure inner shell 30, and thus the low-temperature hydrogen gas that has not yet been completely liquefied is sucked into the mixing section 31 through the low-pressure inlet connecting pipe 12 and the low-pressure ejecting section 15, mixed in the mixing section 31, and then enters the diffusion section 32 of the medium-pressure inner shell 30, and after the kinetic energy of the mixed gas in the diffusion section 32 is converted into pressure energy, the mixed gas is discharged through the discharge section 33 and the medium-pressure outlet connecting pipe 35, and then is recycled in the hydrogen liquefaction device for heat exchange and re-liquefaction into liquid hydrogen.

[0056] It should be noted that the temperature of the low-temperature hydrogen gas in the hydrogen liquefaction device that has not yet been reduced to the liquid hydrogen temperature zone is about 25K, which is lower than the critical point of hydrogen, and the pressure is about 2MPa, which is higher than the critical point of hydrogen, so at this time the low-temperature hydrogen gas as a high-pressure gas source is in a subcritical state, and the hydrogen density in the subcritical state is much greater than that of gaseous hydrogen.

[0057] It needs to be explained here that as a high-pressure gas source, the low-temperature hydrogen gas, when entering the subcritical low-temperature ejector 100 from the high-pressure inlet section 21, has a high pressure and is in a liquid state at this time, and the medium density is large. In the high-pressure nozzle section 22, the pressure energy is converted into kinetic energy, the pressure gradually decreases, the medium is converted from liquid hydrogen to hydrogen gas, the density is greatly reduced by tens of times, and the volume expands rapidly. At this time, if the throat size of the high-pressure nozzle section 22 is not reasonably set, for example, the size suitable for liquid medium, it will cause the throat diameter to be too small, and the medium cannot pass through smoothly, forming an obstruction effect, and when the throat diameter is too large, the medium cannot be fully accelerated in the high-pressure nozzle section 22, and the injection process cannot be completed.

[0058] And the ratio between the first cross-sectional area of the high-pressure inlet section 21 (at the 1-1 cross section, the same below) and the second cross-sectional area of the high-pressure nozzle section 22 (at the 2-2 cross section) is limited to between 7.5 and 15. Regardless of the change in the inlet flow of the high-pressure inlet section 21, the injection process can be completed. Moreover, the ratio between the first cross-sectional area of the high-pressure inlet section 21 and the third cross-sectional area of the diffusion section 32 (at the 3-3 cross section) is limited to between 0.5 and 0.8, fully considering the gas speed reduction, making it suitable for the pipe layout requirements in the cold box.

[0059] Optionally, the subcritical low-temperature ejector 100 can be applied to a hydrogen liquefaction device with a capacity of 0.5 tons / day to 30 tons / day, effectively improving the hydrogen liquefaction rate and improving the system operation efficiency.

[0060] In some embodiments, as shown in Figure 4 The side wall of the medium-pressure inner shell 30 is provided with a measurement guide pipe flow channel 36 corresponding to the position of the mixing section 31 and / or the diffusion section 32, for measuring the pressure of the mixing section 31 and / or the diffusion section 32; wherein the outer shell 10 is provided with a measurement interface 13 corresponding to the measurement guide pipe flow channel 36, as shown in Figure 2 Further, the measurement interface 13 can be welded with a measurement connecting pipe 14.

[0061] In the above scheme, by providing the measurement guide pipe flow channel 36 on the side wall of the medium-pressure inner shell 30 corresponding to the position of the mixing section 31 and / or the diffusion section 32, the gas pressure of the mixing section 31 and / or the diffusion section 32 can be measured, which can analyze whether the working state of the subcritical low-temperature ejector 100 is normal in real time, so as to adjust the process parameters, and then ensure that the hydrogen can be 100% liquefied.

[0062] In some embodiments, as shown in Figure 2As shown, the inner diameter of the outer shell 10 corresponding to the high-pressure inner shell 20 is smaller than the inner diameter of the outer shell 10 corresponding to the medium-pressure inner shell 30. In this way, the flow passage of the conical ring gap-shaped low-pressure ejection section 15 is more uniform, ensuring uniform jet velocity distribution, reducing the impact pressure loss when the low-pressure fluid enters, and inhibiting the generation of initial vortex.

[0063] In some embodiments, the second end of the high-pressure inner shell 20 and the end of the outer shell 10 are provided with flanges, and the two flanges are welded to achieve fixed connection of the second end of the high-pressure inner shell 20 and the end of the outer shell 10. The second end of the medium-pressure inner shell 30 and the end of the outer shell 10 are also provided with flanges, and the two flanges are welded to achieve fixed connection of the second end of the medium-pressure inner shell 30 and the end of the outer shell 10.

[0064] In the above scheme, each interface of the subcritical low-temperature ejector 100 is directly welded, reducing the risk of leakage and ensuring the safety of the equipment.

[0065] In some embodiments, the high-pressure inner shell 20 and the medium-pressure inner shell 30 are in interference fit with the outer shell 10, preventing the medium from flowing according to the preset flow passage and affecting the ejection effect.

[0066] In some embodiments, as shown in Figure 3 As shown, the high-pressure inner shell 20 includes a first high-pressure inner half shell 25 and a second high-pressure inner half shell 26 connected by axial clamping welding, and the first high-pressure inner half shell 25 and the second high-pressure inner half shell 26 are mirror-symmetric in shape. The medium-pressure inner shell 30 includes a first medium-pressure inner half shell 37 and a second medium-pressure inner half shell 38 connected by axial clamping welding, and the first medium-pressure inner half shell 37 and the second medium-pressure inner half shell 38 are mirror-symmetric in shape; wherein the measurement guide tube flow passage 36 is arranged on the first medium-pressure inner half shell 37 and / or the second medium-pressure inner half shell 38.

[0067] As an example, the high-pressure inner shell 20 is a cylindrical blank cut along the axis into a first high-pressure inner half shell 25 and a second high-pressure inner half shell 26, which are then machined respectively to form the high-pressure inlet section 21 and the high-pressure nozzle section 22 inside, and then welded along the cut seam, and then welded to the high-pressure inlet connector 24.

[0068] As shown in Figure 4As shown, the middle pressure inner shell 30 is a cylindrical blank which is cut along the axis to form a first middle pressure inner half shell 37 and a second middle pressure inner half shell 38, and then is machined to form the mixing section 31, the diffusion section 32 and the discharge section 33, and then is welded along the cut seam, and then is welded with the middle pressure outlet connector 35.

[0069] As shown in the drawings, Figure 2 As shown, the outer shell 10 is integrally machined, and is punched to form the injection gas inlet 11 and the measurement interface 13 at positions corresponding to the low pressure injection section 15 and the measurement probe flow channel 36, and then the high pressure inner shell 20 and the middle pressure inner shell 30 are pressed into the cavity of the outer shell 10 by external force.

[0070] The application further provides a hydrogen liquefaction device comprising a multi-stage heat exchanger and the above-mentioned subcritical cryogenic ejector 100, wherein the subcritical cryogenic ejector 100 is arranged between any two heat exchangers of the multi-stage heat exchanger.

[0071] Preferably, the subcritical cryogenic ejector 100 is arranged between the last but one heat exchanger and the last but two heat exchanger.

[0072] As an example, the Chinese patent with application number CN202011189284.5 discloses a hydrogen liquefaction equipment provided with three series-connected turboexpander units, comprising a vacuum box, a hydrogen purification device, a pre-cooling device, a first hydrogen compressor unit, a second hydrogen compressor unit, a first turboexpander unit, a second turboexpander unit, a third turboexpander unit, a first low-temperature adsorber, a second low-temperature adsorber, a heat exchanger, a normal-para hydrogen converter, a regulating valve, a throttle valve, and a liquid hydrogen storage tank; the pre-cooling device, the first turboexpander unit, the second turboexpander unit, the third turboexpander unit, the first low-temperature adsorber, the second low-temperature adsorber, the heat exchanger, the normal-para hydrogen converter, and the throttle valve are all installed in the vacuum box; the regulating valve comprises a first regulating valve and a second regulating valve; the throttle valve comprises a first throttle valve and a second throttle valve; the heat exchanger comprises a first heat exchanger, a second heat exchanger, a third heat exchanger, a fourth heat exchanger, and a fifth heat exchanger; the first heat exchanger is provided with a first high-pressure hydrogen gas passage, a first medium-pressure hydrogen gas passage, a first low-pressure hydrogen gas passage, a first raw hydrogen gas passage, a liquid nitrogen passage, and a nitrogen gas passage; the second heat exchanger is provided with a second high-pressure hydrogen gas passage, a second medium-pressure hydrogen gas passage, a second low-pressure hydrogen gas passage, and two second raw hydrogen gas passages; the third heat exchanger is provided with a third high-pressure hydrogen gas passage, a third medium-pressure hydrogen gas passage, a third low-pressure hydrogen gas passage, and two third raw hydrogen gas passages; the fourth heat exchanger is provided with a fourth high-pressure hydrogen gas passage, a fourth medium-pressure hydrogen gas passage, a fourth low-pressure hydrogen gas passage, and two fourth raw hydrogen gas passages; the fifth heat exchanger is provided with a fifth low-pressure hydrogen gas passage and a fifth raw hydrogen gas passage; the pre-cooling device comprises a liquid nitrogen tank, which is provided with a liquid nitrogen supply pipeline for supplying liquid nitrogen, a liquid nitrogen siphon pipeline for connecting a liquid phase space at the bottom and a gas phase space at the top of the liquid nitrogen tank, and a nitrogen gas discharge pipeline for discharging nitrogen gas in the liquid nitrogen tank; the liquid nitrogen siphon pipeline is communicated with the liquid nitrogen passage in the first heat exchanger, for realizing cooling of the first heat exchanger through liquid nitrogen gasification heat absorption; the nitrogen gas discharge pipeline is communicated with the nitrogen gas passage in the first heat exchanger; the normal-para hydrogen converter comprises a first normal-para hydrogen converter, a second normal-para hydrogen converter, a third normal-para hydrogen converter, a fourth normal-para hydrogen converter, a fifth normal-para hydrogen converter, and a sixth normal-para hydrogen converter; the sixth normal-para hydrogen converter is installed in the fifth heat exchanger; the hydrogen purification device is used for purifying raw hydrogen gas, the outlet of the hydrogen purification device is communicated with the inlet of the first low-temperature adsorber through the first raw hydrogen gas passage, the outlet of the first low-temperature adsorber is sequentially connected with the first normal-para hydrogen converter and the second normal-para hydrogen converter; the inlet of one second raw hydrogen gas passage is communicated with the outlet of the second normal-para hydrogen converter, and the outlet is sequentially communicated with the inlet of a third raw hydrogen gas passage through the third normal-para hydrogen converter and another second raw hydrogen gas passage.The two third raw hydrogen channels are communicated through the fourth ortho-para hydrogen converter, and the outlet of the other third raw hydrogen channel is communicated with the inlet of a fourth raw hydrogen channel; the two fourth raw hydrogen channels are communicated through the fifth ortho-para hydrogen converter, and the outlet of the other fourth raw hydrogen channel is communicated with the inlet of the fifth raw hydrogen channel; the sixth ortho-para hydrogen converter is arranged in the fifth raw hydrogen channel, and the outlet of the fifth raw hydrogen channel is communicated with the inlet of the liquid hydrogen storage tank through the first throttling valve; the inlet of the first hydrogen compressor unit is communicated with the outlet of the first low-pressure hydrogen channel, and the outlet is communicated with the inlet of the second hydrogen compressor unit and the outlet of the first medium-pressure hydrogen channel; the outlet of the second hydrogen compressor unit is communicated with the inlet of the first high-pressure hydrogen channel; the first regulating valve is connected between the inlet and the outlet of the first hydrogen compressor unit; the second regulating valve is connected between the inlet and the outlet of the second hydrogen compressor unit; the second low-temperature adsorber is connected between the outlet of the first high-pressure hydrogen channel and the inlet of the second high-pressure hydrogen channel; one outlet of the second high-pressure hydrogen channel is communicated with the inlet of the fourth medium-pressure hydrogen channel through the first turbine expander unit, the second turbine expander unit and the third turbine expander unit connected in series, and the other outlet is communicated with the third high-pressure hydrogen channel, the fourth high-pressure hydrogen channel and the second throttling valve connected in series, and the outlet of the second throttling valve is communicated with the inlet of the fifth low-pressure hydrogen channel; the fourth medium-pressure hydrogen channel, the third medium-pressure hydrogen channel, the second medium-pressure hydrogen channel and the first medium-pressure hydrogen channel are communicated in series; the fifth low-pressure hydrogen channel, the fourth low-pressure hydrogen channel, the third low-pressure hydrogen channel, the second low-pressure hydrogen channel and the first low-pressure hydrogen channel are connected in series; the hydrogen purification device, the first low-temperature adsorber, the ortho-para hydrogen converter, the first throttling valve and the liquid hydrogen storage tank form a hydrogen cooling and liquefaction system; the first hydrogen compressor unit, the second hydrogen compressor unit, the first turbine expander unit, the second turbine expander unit, the third turbine expander unit, the second low-temperature adsorber, the regulating valve and the second throttling valve form a hydrogen refrigeration cycle system, and the hydrogen refrigeration cycle system uses hydrogen as a refrigerant; the second ortho-para hydrogen converter is installed in the liquid nitrogen tank and immersed in liquid nitrogen; the first low-temperature adsorber is provided with two, and the two first low-temperature adsorbers are connected in parallel.

[0073] When the subcritical low-temperature ejector 100 of the present application is applied to the hydrogen liquefaction device described above, the subcritical low-temperature ejector 100 can be placed near the sixth primary-secondary hydrogen converter, the high-pressure inlet connecting pipe 24 is connected with the fifth primary-secondary hydrogen converter, that is, the high-pressure inlet flow comes from the hydrogen flow of the fifth primary-secondary hydrogen converter, the low-pressure inlet connecting pipe 12 is connected with the liquid hydrogen storage tank, that is, the low-pressure inlet flow comes from the liquid hydrogen storage tank, and the medium-pressure outlet connecting pipe 35 is connected with the sixth primary-secondary hydrogen converter, that is, after the high-pressure inlet flow and the low-pressure inlet flow pass through the subcritical low-temperature ejector 100, they are mixed into a medium-pressure flow, then pass through the fifth raw hydrogen channel for the last heat exchange, the first throttling valve throttling and pressure reduction, and are re-liquefied into liquid hydrogen, thereby improving the liquefaction rate of the device.

[0074] In other words, after the improvement of the hydrogen liquefaction device provided in the Chinese patent with the application number CN202011189284.5, the hydrogen flow from the fifth primary-secondary hydrogen converter no longer directly enters the sixth primary-secondary hydrogen converter, but enters the high-pressure inlet section 21 of the subcritical low-temperature ejector 100, in addition, a flow path is led out from the liquid hydrogen storage tank and connected with the low-pressure inlet connecting pipe 12 of the subcritical low-temperature ejector 100, and the medium-pressure flow from the medium-pressure outlet connecting pipe 35 of the subcritical low-temperature ejector 100 enters the sixth primary-secondary hydrogen converter.

[0075] In the above scheme, since the temperature difference between the high-pressure flow and the low-pressure flow between the last first-stage heat exchanger and the last second-stage heat exchanger is small, the two are more easily mixed, and the energy and temperature lost after mixing are low, therefore, by arranging the subcritical low-temperature ejector 100 at this position and after the pressure reduction by the first throttling valve, the hydrogen can be 100% re-liquefied into liquid hydrogen, thereby more effectively improving the liquefaction rate of the device.

[0076] It should be noted that the subcritical low-temperature ejector 100 is arranged inside the cold box, which is a high-vacuum box, and the internal temperature can be stably maintained. Therefore, in actual use, the subcritical low-temperature ejector 100 needs to be wrapped with thermal insulation materials, which can better maintain the temperature of the liquid hydrogen in the device and reduce the influence of the external environment temperature on the performance of the device.

[0077] The above only describes the preferred embodiments of the present application and is not intended to limit the present application in any form. Although the present application has been disclosed as above with the preferred embodiments, it is not intended to limit the present application, and any person skilled in the art can make some changes or modifications to the above-mentioned technical content without departing from the technical solution range of the present application to obtain equivalent embodiments with equivalent changes, but any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present application shall still fall within the scope of the present application.

Claims

1. A subcritical cryogenic ejector for a hydrogen liquefaction device, characterized in that, The subcritical cryogenic ejector has an ejector channel inside, which includes a high-pressure inlet section, a high-pressure nozzle section, a low-pressure ejector section, a mixing section, and a diffusion section. Wherein, the inlet of the high-pressure inlet section has a first cross-sectional area, the outlet of the high-pressure nozzle section has a second cross-sectional area, and the outlet of the diffuser section has a third cross-sectional area; The ratio S1 between the area of ​​the first cross-section and the area of ​​the second cross-section satisfies the following formula: 7.5＜S1＜15； The ratio S2 between the area of ​​the first cross-section and the area of ​​the third cross-section satisfies the following formula: 0.5＜S2＜0.8。 2. The subcritical cryogenic ejector for hydrogen liquefaction equipment according to claim 1, characterized in that, The subcritical cryogenic ejector includes: The outer casing has an ejector gas inlet on its side wall; A high-pressure inner shell, wherein the high-pressure inlet section and the high-pressure nozzle section are sequentially formed in the high-pressure inner shell, the high-pressure inner shell is disposed in the outer shell and the first end of the high-pressure inner shell is configured as a conical structure, and the first end of the high-pressure inner shell is located downstream of the ejector gas inlet; A medium-pressure inner shell, wherein the mixing section and the diffusion section are sequentially formed in the medium-pressure inner shell, the medium-pressure inner shell is disposed in the outer shell and the first end of the medium-pressure inner shell is configured as a conical structure, the first end of the medium-pressure inner shell is located downstream of the first end of the high-pressure inner shell, and a low-pressure ejector section communicating with the ejector gas inlet is formed between the first end of the high-pressure inner shell and the first end of the high-pressure inner shell.

3. The subcritical cryogenic ejector for hydrogen liquefaction equipment according to claim 2, characterized in that, A measuring inlet channel is provided on the side wall of the medium-pressure inner shell at the position corresponding to the mixing section and / or the diffusion section, for measuring the pressure of the mixing section and / or the diffusion section; A measurement interface is provided on the outer casing at a position corresponding to the measurement guide channel.

4. The subcritical cryogenic ejector for hydrogen liquefaction equipment according to claim 2, characterized in that, The inner diameter of the outer shell corresponding to the high-pressure inner shell is smaller than the inner diameter of the outer shell corresponding to the medium-pressure inner shell.

5. The subcritical cryogenic ejector for a hydrogen liquefaction device according to any one of claims 2 to 4, characterized in that, The second end of the high-pressure inner shell is welded to the end of the outer shell, and the second end of the medium-pressure inner shell is welded to the end of the outer shell.

6. The subcritical cryogenic ejector for a hydrogen liquefaction device according to any one of claims 2 to 4, characterized in that, The high-pressure inner shell and the medium-pressure inner shell are interference-fitted with the outer shell.

7. The subcritical cryogenic ejector for a hydrogen liquefaction device according to any one of claims 2 to 4, characterized in that, The high-pressure inner shell includes a first high-pressure inner half shell and a second high-pressure inner half shell that are axially fastened and welded together. The first high-pressure inner half shell and the second high-pressure inner half shell have a mirror-symmetrical structure in shape.

8. The subcritical cryogenic ejector for hydrogen liquefaction equipment according to claim 3, characterized in that, The medium-pressure inner shell includes a first medium-pressure inner half shell and a second medium-pressure inner half shell that are fastened and welded together along the axial direction. The first medium-pressure inner half shell and the second medium-pressure inner half shell have a mirror-symmetrical structure in shape. The measuring guide channel is disposed on the first medium-pressure inner half shell and / or the second medium-pressure inner half shell.

9. A hydrogen liquefaction device, characterized in that, include: Multistage heat exchanger; as well as The subcritical cryogenic ejector for a hydrogen liquefaction equipment according to any one of claims 1 to 8, wherein the subcritical cryogenic ejector is disposed between any two stages of heat exchangers.

10. The hydrogen liquefaction equipment according to claim 9, characterized in that, The subcritical cryogenic ejector is located between the penultimate and penultimate heat exchangers.

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