Liquefied hydrogen equipment
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Patents
- Current Assignee / Owner
- KAWASAKI JUKOGYO KK
- Filing Date
- 2022-12-28
- Publication Date
- 2026-07-30
Smart Images
Figure 0007897790000001 
Figure 0007897790000002 
Figure 0007897790000003
Abstract
Description
Technical Field
[0001] The present disclosure relates to a liquefied hydrogen facility for handling liquefied hydrogen.
Background Art
[0002] Liquefied hydrogen facilities for liquefying, storing, and loading hydrogen gas are known. For example, Patent Document 1 below discloses a liquefied hydrogen facility including a liquefier (liquefied hydrogen production device) for liquefying raw hydrogen gas supplied from a raw hydrogen gas supply source, a storage tank for storing the liquefied hydrogen liquefied by the liquefier, and a loading line for loading the liquefied hydrogen from the storage tank to a carrier ship (liquefied hydrogen tanker).
Prior Art Documents
Patent Documents
[0003]
Patent Document 1
Summary of the Invention
Problems to be Solved by the Invention
[0004] In the above-described liquefied hydrogen facility, when loading liquefied hydrogen from the storage tank to the carrier ship, if the loading line remains at room temperature, the temperature difference between the liquefied hydrogen and the loading line may be too large, causing various problems. Therefore, it is necessary to perform preliminary cooling to cool the loading line in advance before loading the liquefied hydrogen to the carrier ship. Such preliminary cooling can be performed not only on the loading line but also on various pipes and equipment through which liquefied hydrogen flows during loading (hereinafter referred to as cooling targets).
[0005] Here, it is proposed to use boil-off gas present in the gas phase of the storage tank, that is, low-temperature hydrogen gas produced by the evaporation of liquefied hydrogen in the storage tank, as the medium for cooling the object to be cooled down. However, the boil-off gas in the storage tank may not have sufficient pressure to cool the object to be cooled down. In other words, due to insufficient pressure of the boil-off gas, it may not be possible to distribute the boil-off gas throughout the object to be cooled down, or the time required to cool the object to be cooled down may be prolonged.
[0006] This disclosure is made in view of the circumstances described above, and aims to provide a liquefied hydrogen facility capable of efficiently cooling the object to be cooled down. [Means for solving the problem]
[0007] To solve the aforementioned problems, a liquefied hydrogen facility according to one aspect of the present disclosure comprises a liquefier for cooling and liquefying hydrogen gas, a storage tank for storing the liquefied hydrogen liquefied by the liquefier, a liquefied hydrogen supply line connecting the liquefier and the storage tank, a sub-tank capable of storing hydrogen gas at a pressure higher than the pressure of the gas phase of the storage tank, a branch line connecting the liquefier and the sub-tank, and a cooling line connecting the sub-tank to a cool-down target which is subject to pre-cooling performed before the liquefied hydrogen is supplied. [Effects of the Invention]
[0008] The liquefied hydrogen equipment described herein can efficiently cool the object to be cooled down. [Brief explanation of the drawing]
[0009] [Figure 1] This is a system diagram showing the overall configuration of a liquefied hydrogen facility according to the first embodiment of this disclosure. [Figure 2] This is a diagram equivalent to Figure 1, illustrating the operation of the aforementioned liquefied hydrogen equipment when the operation phase is the startup phase. [Figure 3] This is a diagram equivalent to Figure 1, illustrating the operation of the aforementioned liquefied hydrogen equipment when the operational phase is the storage phase. [Figure 4] This is a diagram equivalent to Figure 1, illustrating the operation of the aforementioned liquefied hydrogen equipment when the operational phase is the cargo handling phase. [Figure 5] This is a diagram equivalent to Figure 1, illustrating the operation of the aforementioned liquefied hydrogen equipment when the operational phase is the cargo handling preparation phase. [Figure 6] This is a system diagram showing the overall configuration of a liquefied hydrogen facility according to the second embodiment of this disclosure. [Modes for carrying out the invention]
[0010] (1) First Embodiment [Configuration of liquefied hydrogen facilities] Figure 1 is a system diagram showing the overall configuration of a liquefied hydrogen facility 1 according to the first embodiment of this disclosure. The liquefied hydrogen facility 1 shown in this figure is equipment for liquefying hydrogen gas, storing it, and loading the stored liquefied hydrogen onto a transport ship 100 (carrier). Specifically, the liquefied hydrogen facility 1 comprises a raw material supply source 2, a liquefier 3, a storage tank 4, a sub-tank 5, and a pump 6. The raw material supply source 2 is a supply source that supplies raw material hydrogen gas to the liquefier 3 before liquefaction. The liquefier 3 is a device that liquefies the raw material hydrogen gas supplied from the raw material supply source 2. The storage tank 4 is a tank that stores the liquefied hydrogen produced by the liquefier 3. The sub-tank 5 is a tank that stores hydrogen gas in a pressurized state. The pump 6 is a pump that discharges liquefied hydrogen from the storage tank 4 to the transport ship 100.
[0011] Each of the elements described above is connected to one another via multiple passages. Specifically, the liquefied hydrogen facility 1 includes a raw material supply line 11 connecting the raw material source 2 and the liquefier 3, a liquefied hydrogen supply line 12 connecting the liquefier 3 and the storage tank 4, a cargo handling line 13 connecting the storage tank 4 and the transport vessel 100, a branch line 15 connecting the liquefied hydrogen supply line 12 and the sub-tank 5, a cooling line 16 connecting the sub-tank 5 and the cargo handling line 13, and a recirculation line 17 connecting the cooling line 16 and the raw material supply line 11.
[0012] The raw material source 2 generates hydrogen gas and supplies this hydrogen gas to the liquefier 3 as a raw material for liquefied hydrogen. The raw material hydrogen gas supplied from the raw material source 2 to the liquefier 3 is pressurized to, for example, several MPa. The raw material source 2 can be any type of device that can generate hydrogen gas, but for example, a device that generates hydrogen gas from hydrocarbons such as methane by steam reforming can be used as the raw material source 2. Alternatively, a device that generates hydrogen gas by electrolysis of water may be used as the raw material source 2.
[0013] High-pressure raw hydrogen gas supplied from raw material source 2 is introduced to liquefier 3 through raw material supply line 11. Liquefier 3 cools and expands the introduced high-pressure raw hydrogen gas to liquefy it and produce liquid hydrogen. Specifically, liquefier 3 includes a cooler 31 that cools the hydrogen gas by heat exchange and an expansion valve 32 (Joule-Thomson valve) that expands and liquefies the hydrogen gas after it has been cooled by the cooler 31. The cooler 31 may include, for example, a refrigeration cycle section that lowers the working medium (e.g., hydrogen) to an extremely low temperature using a refrigeration cycle such as a compressor or expansion turbine, and a heat exchange section that cools the raw hydrogen gas to a state just before liquefaction by heat exchange using the refrigeration cycle section as a cold source. The expansion valve 32 receives the high-pressure raw hydrogen gas discharged from the cooler 31 and causes Joule-Thomson expansion (isoenthalpic expansion). As a result, the raw hydrogen gas is liquefied and extremely low-temperature liquid hydrogen is produced.
[0014] The liquefied hydrogen produced by the liquefier 3 is introduced into the storage tank 4 via the liquefied hydrogen supply line 12. The storage tank 4 stores the introduced liquefied hydrogen while keeping it cool. In this embodiment, the storage tank 4 is a flat-bottomed cylindrical tank with a spherical roof. The storage tank 4 is also a multi-shell tank including an inner tank 41 that defines the storage space for liquefied hydrogen and an outer tank 42 that is located outside the inner tank 41 and forms an insulating layer between it and the inner tank 41. Although only the outer tank 42 and inner tank 41 are shown in Figure 1, an intermediate tank may be provided between the outer tank 42 and the inner tank 41. In other words, the storage tank 4 in this embodiment can be any multi-shell structure including the outer tank 42 and the inner tank 41, and may be a double-shell tank or a triple-shell tank.
[0015] Inside the storage tank 4, there is boil-off gas (BOG) generated by the evaporation of liquefied hydrogen that has received heat input. In other words, a gas phase section 4a filled with this boil-off gas is formed at the top of the storage tank 4. Although details are omitted, the storage tank 4 is connected to a BOG line to appropriately remove boil-off gas from the gas phase section 4a so that the internal tank pressure, which is the pressure of the boil-off gas in the gas phase section 4a, does not exceed a predetermined design pressure. The boil-off gas removed through the BOG line is returned, for example, to the raw material supply line 11 and reliquefied in the liquefier 3.
[0016] The liquefied hydrogen stored in the storage tank 4 is discharged from the storage tank 4 by the pump 6 during the cargo handling phase, which will be described later, in which the liquefied hydrogen is loaded onto the transport ship 100. The pump 6 draws in the liquefied hydrogen from the storage tank 4 and discharges it downstream, and includes, for example, a rotating element such as an impeller and a drive source such as an electric motor that rotates the rotating element. The liquefied hydrogen discharged from the pump 6 is supplied to the transport ship 100 through the cargo handling line 13.
[0017] The cargo handling line 13 is connected to the carrier ship 100 via the loader 101. The loader 101 is installed at the port where the carrier ship 100 docks, and loads the liquefied hydrogen sent from the cargo handling line 13 onto the carrier ship 100. The loader 101 includes a multi-joint loading arm 101a. The loading arm 101a is detachably connected to the downstream end of the cargo handling line 13.
[0018] The sub-tank 5 is a small pressure-resistant tank smaller in size than the storage tank 4. That is, the sub-tank 5 has pressure resistance to withstand a higher pressure than the storage tank 4 and has a smaller tank diameter than the storage tank 4. In the present embodiment, the sub-tank 5 has a single-shell structure instead of a multi-shell structure like the storage tank 4.
[0019] The sub-tank 5 is provided with a vaporizer 51 inside. The vaporizer 51 converts the liquefied hydrogen into hydrogen gas by vaporizing it, for example, by atomizing and injecting the liquefied hydrogen.
[0020] The branch line 15 is arranged to branch from the liquefied hydrogen supply line 12 and reach the vaporizer 51 in the sub-tank 5. The liquefied hydrogen introduced into the vaporizer 51 through the branch line 15 is vaporized in the sub-tank 5 by the vaporizer 51. The hydrogen gas generated by the vaporization is stored in the sub-tank 5 in a pressurized state. In other words, the branch line 15 connects the outlet of the expansion valve 32 of the liquefier 3 and the vaporizer 51 so that the liquefied hydrogen derived from the liquefier 3 can be introduced into the sub-tank 5 while being vaporized.
[0021] The liquefied hydrogen supply line 12 and the branch line 15 are equipped with valves 21 and 22 for switching the supply destination of liquefied hydrogen between the storage tank 4 and the sub-tank 5. Specifically, a first valve 21 is provided on the liquefied hydrogen supply line 12 that can be opened and closed, and a second valve 22 is provided on the branch line 15 that can be opened and closed. When supplying liquefied hydrogen to the storage tank 4, that is, when storing liquefied hydrogen from the liquefier 3 in the storage tank 4, the first valve 21 is opened and the second valve 22 is closed. On the other hand, when supplying liquefied hydrogen to the sub-tank 5, that is, when introducing liquefied hydrogen from the liquefier 3 into the sub-tank 5 while vaporizing it, the first valve 21 is closed and the second valve 22 is opened.
[0022] The cooling line 16 is arranged to extend from the sub-tank 5 and lead to the cargo handling line 13. A third valve 23 is provided on the cooling line 16 so as to be openable and closable. When the third valve 23 is opened, hydrogen gas from the sub-tank 5 is supplied to the cargo handling line 13 through the cooling line 16.
[0023] The reflux line 17 is arranged to branch off from a position upstream of the third valve 23 in the cooling line 16 and lead to the raw material supply line 11. A fourth valve 24 and a compressor 26 are provided on the reflux line 17. The compressor 26 is a device that pressurizes hydrogen gas toward the raw material supply line 11 and may include, for example, a rotating element such as an impeller and a drive source such as a motor that rotates the rotating element. The fourth valve 24 is an on / off valve provided between the compressor 26 and the sub-tank 5. When the fourth valve 24 is opened and the compressor 26 is driven, hydrogen gas in the sub-tank 5 is supplied to the raw material supply line 11 through the reflux line 17.
[0024] [Operation of liquefied hydrogen equipment] Next, the operation of the liquefied hydrogen facility 1 in its various operational phases will be described. In this embodiment, the operational phases of the liquefied hydrogen facility 1 are classified into four phases: the startup phase, the storage phase, the handling phase, and the handling preparation phase. The details of each phase are as follows.
[0025] (Startup Phase) The startup phase is the phase in which the liquefier 3 is started and the liquefaction of the raw hydrogen gas begins. Figure 2 is a diagram illustrating the operation during this startup phase. As shown in this figure, during the startup phase, the liquefier 3 is started, the second valve 22 and the fourth valve 24 are opened, and the compressor 26 is driven. Meanwhile, the first valve 21 and the third valve 23 are closed, and the pump 6 is stopped. In Figure 2, closed valves are shown in black, and open valves are shown in white. Also, since the transport ship 100 is generally not yet docked during the startup phase, the transport ship 100 and the loading machine 101 are shown with dashed lines in Figure 2. This is also the case in Figures 3 and 5 (storage phase and cargo handling preparation phase), which will be described later.
[0026] Here, even when the liquefaction of the raw hydrogen gas begins by starting up the liquefier 3, the cooling performance does not function sufficiently for a predetermined period from the start up of the liquefier 3. For this reason, for a predetermined period from the start up of the liquefier 3, the fluid discharged from the expansion valve 32 of the liquefier 3 may be a gas-liquid two-phase fluid in which liquefied hydrogen and hydrogen gas are mixed. As described above, in the start-up phase, the second valve 22 is opened and the first valve 21 is closed, so the gas-liquid two-phase fluid discharged from the liquefier 3 is introduced into the sub-tank 5 through the branch line 15. Inside the sub-tank 5, the liquid component of the gas-liquid two-phase fluid is vaporized by the vaporizer 51. As a result, the sub-tank 5 is filled with hydrogen gas. The hydrogen gas in the sub-tank 5 is drawn in by the compressor 26 on the reflux line 17 and pressurized to the downstream side. In other words, the gas-liquid two-phase fluid discharged from the liquefier 3 is converted into hydrogen gas in the sub-tank 5, and then recirculated to the raw material supply line 11 via the reflux line 17. The refluxed hydrogen gas supplied to the raw material supply line 11 merges with the raw material hydrogen gas from the raw material supply source 2 and is reliquefied in the liquefier 3.
[0027] (Storage Phase) The storage phase is the phase in which liquefied hydrogen supplied from the liquefier 3 is stored in the storage tank 4. Figure 3 is a diagram illustrating the operation during this storage phase. As shown in this figure, during the storage phase, the liquefier 3 is driven and the first valve 21 is opened. Meanwhile, the second valve 22, the third valve 23, and the fourth valve 24 are closed, and the pump 6 and the compressor 26 are stopped.
[0028] As described above, with each component controlled, in the storage phase, the liquefied hydrogen produced in the liquefier 3 is supplied to the storage tank 4 through the liquefied hydrogen supply line 12, and the liquefied hydrogen is stored in the storage tank 4.
[0029] (Loading / unloading phase) The loading / unloading phase is the phase in which liquefied hydrogen is loaded from the storage tank 4 to the transport ship 100. Figure 4 is a diagram illustrating the operation during this loading / unloading phase. As shown in this figure, during the loading / unloading phase, the liquefier 3 and pump 6 are driven, and the first valve 21 is opened. Meanwhile, the second valve 22, the third valve 23, and the fourth valve 24 are closed, and the compressor 26 is stopped.
[0030] As described above, with each component controlled, during the cargo handling phase, liquefied hydrogen discharged from the storage tank 4 by the pump 6 is supplied to the transport ship 100 through the cargo handling line 13, and liquefied hydrogen supplied from the liquefied hydrogen 3 is replenished in the storage tank 4 through the liquefied hydrogen supply line 12.
[0031] (Loading and unloading preparation phase) The cargo handling preparation phase is a phase in which the cargo handling line 13 is cooled as a pre-processing step before the cargo handling phase. Figure 5 is a diagram illustrating the operation in this cargo handling preparation phase. As shown in this figure, in the cargo handling preparation phase, the liquefier 3 is driven and the second valve 22 and the third valve 23 are opened. On the other hand, the first valve 21 and the fourth valve 24 are closed and the pump 6 and the compressor 26 are stopped.
[0032] As described above, with each component controlled, in the cargo handling preparation phase, liquefied hydrogen from the liquefier 3 is vaporized in the sub-tank 5 and converted into low-temperature hydrogen gas. Simultaneously, the hydrogen gas in the sub-tank 5 flows into the downstream cooling line 16 due to the pressure generated by the liquefier 3. In other words, the liquefied hydrogen discharged from the liquefier 3 is converted into low-temperature hydrogen gas in the sub-tank 5 and then introduced into the cargo handling line 13 via the cooling line 16. The low-temperature hydrogen gas introduced into the cargo handling line 13 cools the various pipes and other components that make up the cargo handling line 13. This allows for pre-cooling of the cargo handling line 13, through which liquefied hydrogen will flow when the cargo handling phase begins, thereby reducing the temperature difference between the liquefied hydrogen and the cargo handling line 13. The cargo handling line 13 is connected to a predetermined recovery line, through which hydrogen gas is recovered.
[0033] Furthermore, during the cargo handling preparation phase, the opening of the expansion valve 32 in the liquefier 3 is adjusted to the open side compared to other phases. This suppresses the degree to which the high-pressure hydrogen gas discharged from the cooler 31 expands in the expansion valve 32, and increases the pressure at the outlet of the expansion valve 32 compared to other phases. This increase in the outlet pressure of the expansion valve 32 increases the pressure of the liquefied hydrogen introduced from the expansion valve 32 through the branch line 15 to the vaporizer 51 of the sub-tank 5, and increases the pressure of the hydrogen gas discharged from the vaporizer 51. This makes it possible to maintain a relatively high internal pressure in the sub-tank 5, and allows hydrogen gas at a pressure higher than that of the gas phase 4a of the storage tank 4 to be stored in the sub-tank 5. In other words, during the cargo handling preparation phase, the opening of the expansion valve 32 is adjusted to the open side so that hydrogen gas at a pressure higher than that of the gas phase 4a of the storage tank 4 can be stored in the sub-tank 5.
[0034] Furthermore, as described above, in the cargo handling preparation phase, the opening of the expansion valve 32 is adjusted to the open side, so the fluid discharged from the expansion valve 32 may contain not only liquefied hydrogen but also a small amount of hydrogen gas. In other words, in the cargo handling preparation phase, the fluid (hydrogen) supplied from the liquefier 3 to the sub-tank 5 may consist only of liquefied hydrogen, or it may be a gas-liquid two-phase fluid containing liquefied hydrogen and hydrogen gas.
[0035] [Effects and Effects] As described above, in this embodiment, the liquefied hydrogen supply line 12 through which hydrogen gas flows from the liquefier 3 to the storage tank 4 and the sub-tank 5 capable of storing hydrogen gas at a pressure higher than the gas phase 4a of the storage tank 4 are connected to each other via a branch line 15, and the cargo handling line 13 extending from the storage tank 4 to the transport ship 100 and the sub-tank 5 are connected to each other via a cooling line 16. With this configuration, there is an advantage that the cargo handling line 13 (target for cooling down) can be efficiently cooled when it is pre-cooled during the cargo handling preparation phase.
[0036] In other words, in this embodiment, liquefied hydrogen discharged from the liquefier 3 is introduced into the sub-tank 5 via the branch line 15 and vaporized, thereby accumulating relatively high-pressure and low-temperature hydrogen gas in the sub-tank 5. This hydrogen gas is then supplied to the loading line 13 during the loading preparation phase, allowing the loading line 13 to be efficiently pre-cooled before the liquefied hydrogen is loaded through the loading line 13.
[0037] Here, since boil-off gas generated by the evaporation of liquefied hydrogen is present in the gas phase 4a at the top of the storage tank 4, it is conceivable to use the boil-off gas in the gas phase 4a as a cooling medium when pre-cooling the loading / unloading line 13 as described above. However, the storage tank 4, which has a multi-walled structure to ensure high cooling performance, has limitations in its pressure resistance, and it may not be possible to raise the pressure in the gas phase 4a (tank internal pressure) sufficiently high. If the pressure in the gas phase 4a is insufficient, it may not be possible to distribute the boil-off gas throughout the loading / unloading line 13, or the time required to sufficiently cool the loading / unloading line 13 may be prolonged.
[0038] In contrast, in this embodiment, during the cargo handling preparation phase, hydrogen gas from the sub-tank 5 is supplied to the cargo handling line 13 instead of the boil-off gas (hydrogen gas in the gas phase section 4a) mentioned above. In this case, since the pressure resistance of the sub-tank 5 is higher than that of the storage tank 4, the sub-tank 5 can be pressurized so that its internal pressure is higher than the pressure in the gas phase section 4a, and then relatively high-pressure hydrogen gas can be supplied from the pressurized sub-tank 5 to the cargo handling line 13. In other words, according to this embodiment, relatively high-pressure and low-temperature hydrogen gas can be supplied from the sub-tank 5 to the cargo handling line 13, so the cargo handling line 13 can be cooled efficiently, and the man-hours required in the cargo handling preparation phase can be reduced.
[0039] Furthermore, in this embodiment, the outlet of the expansion valve 32 and the sub-tank 5 are connected to each other via a branch line 15 that branches off from the liquefied hydrogen supply line 12 between the expansion valve 32 of the liquefier 3 and the storage tank 4. This allows the sufficiently low-temperature liquefied hydrogen discharged from the expansion valve 32 to be vaporized and introduced into the sub-tank 5, thereby keeping the temperature of the hydrogen gas accumulated in the sub-tank 5 low. Additionally, by adjusting the opening degree of the expansion valve 32, the depressurizing effect of the expansion valve 32 can be suppressed, allowing the pressure of the hydrogen gas in the sub-tank 5 to be set higher. In other words, in this embodiment, relatively high-pressure and low-temperature hydrogen gas suitable for pre-cooling can be accumulated in the sub-tank 5.
[0040] Furthermore, in this embodiment, a recirculation line 17 is provided that branches off from the cooling line 16 and leads to the raw material supply line 11. This allows the hydrogen gas in the sub-tank 5 to be reliquefied in the liquefier 3 and effectively utilized when the cargo handling preparation phase is not underway. For example, during the startup phase when the liquefier 3 is activated, the gas-liquid two-phase fluid discharged from the liquefier 3 can be converted into hydrogen gas and stored in the sub-tank 5. The hydrogen gas in the sub-tank 5 can then be returned to the liquefier 3 for reliquefaction. This prevents the gas-liquid two-phase fluid from being introduced into the storage tank 4 while ensuring efficient use of hydrogen.
[0041] (2) Second Embodiment Figure 6 is a system diagram showing a liquefied hydrogen equipment 1A according to the second embodiment of this disclosure. In this second embodiment, the source of the branch line 15 differs from that of the first embodiment described above. That is, in the first embodiment (Figures 1-5), the branch line 15 branched from the liquefied hydrogen supply line 12 between the expansion valve 32 of the liquefier 3 and the storage tank 4, whereas in the second embodiment (Figure 6), the branch line 15 branches from between the cooler 31 and the expansion valve 32 in the liquefier 3. The features of the second embodiment will be described below, focusing on this difference. In other words, the liquefied hydrogen equipment 1A of the second embodiment has the same structure as the first embodiment, except for the point relating to the branch line 15.
[0042] As shown in Figure 6, the branch line 15 is arranged to branch off from the relay line 19 connecting the cooler 31 and the expansion valve 32 and reach the sub-tank 5. The relay line 19 is a line for introducing high-pressure, low-temperature hydrogen gas, i.e., hydrogen gas just before liquefaction, which is discharged from the cooler 31, to the expansion valve 32, and corresponds to the "relay section" in this disclosure. The high-pressure, low-temperature hydrogen gas flowing through the relay line 19 is introduced into the sub-tank 5 through the branch line 15. As a result, relatively high-pressure hydrogen gas is stored in the sub-tank 5. Note that some of the hydrogen gas just before liquefaction flowing from the relay line 19 to the branch line 15 may be liquefied. In other words, the fluid (hydrogen) supplied from the relay line 19 to the sub-tank 5 may consist only of hydrogen gas, or it may be a gas-liquid two-phase fluid containing liquefied hydrogen and hydrogen gas.
[0043] A pressure reducing valve 40 is provided in the middle of the branch line 15. The pressure reducing valve 40 is a valve that reduces the pressure of the high-pressure hydrogen gas led out from the relay line 19 described above. For example, the pressure reducing valve 40 can be a valve that expands the hydrogen gas using the Joule-Thomson method, similar to the expansion valve 32 (Joule-Thomson valve) of the liquefaction unit 3. In this case, the pressure reducing valve 40 may expand the hydrogen gas until at least a portion of it is liquefied. The liquid component produced by this partial liquefaction is vaporized by the vaporizer 51 in the sub-tank 5, converted into hydrogen gas, and then stored in the sub-tank 5.
[0044] According to the second embodiment described above, the internal pressure of the sub-tank 5 can be set to a sufficiently high level by utilizing the hydrogen gas at a sufficiently high pressure before it is expanded (liquefied) by the expansion valve 32 of the liquefier 3. Therefore, the cargo handling line 13 can be efficiently cooled by supplying hydrogen gas at a sufficiently high pressure to the cargo handling line 13 during the cargo handling preparation phase.
[0045] Furthermore, in the second embodiment, a pressure reducing valve 40 is provided in the middle of the branch line 15, so that the high-pressure hydrogen gas discharged from the relay line 19 can be appropriately reduced in pressure by the pressure reducing valve 40 before being introduced into the sub-tank 5. This eliminates the need to excessively increase the pressure resistance (strength) of the sub-tank 5, and allows the cargo handling line 13 to be cooled rationally and efficiently.
[0046] (3) Variant While preferred embodiments of the present disclosure have been described above, the disclosure is not limited thereto, and variations such as the following are possible.
[0047] In each of the embodiments described above, before loading liquefied hydrogen onto the transport vessel 100 through the loading line 13, the loading line 13 is pre-cooled using the hydrogen gas accumulated in the sub-tank 5 as part of the loading preparation phase. However, the object of pre-cooling during this loading preparation phase, i.e., the object of cool-down, is not limited to the loading line 13, but can be any pipes or equipment through which liquefied hydrogen will flow in the subsequent loading phase.
[0048] In each of the above embodiments, during the startup phase when the liquefier 3 is activated, the gas-liquid two-phase fluid discharged from the liquefier 3 is converted to hydrogen gas and stored in the sub-tank 5, and the hydrogen gas is recirculated from the sub-tank 5 to the upstream side of the liquefier 3 through the recirculation line 17. However, the fluid from the liquefier 3 is also prone to becoming a gas-liquid two-phase fluid when the liquefier 3 is stopped. For this reason, the same hydrogen gas recirculation may be performed during the shutdown phase when the liquefier 3 is stopped.
[0049] In each of the above embodiments, a first valve 21 is provided in the liquefied hydrogen supply line 12 and a second valve 22 is provided in the branch line 15. However, a three-way valve may be provided at the branching point between the liquefied hydrogen supply line 12 and the branch line 15, and the functions of both the first valve 21 and the second valve 22 may be integrated into this three-way valve.
[0050] In each of the above embodiments, the liquefaction unit 3 for liquefying hydrogen gas includes an expansion valve 32 for Joule-Thomson expansion of the hydrogen gas. However, the liquefaction unit 3 only needs to include an expansion means for expanding the hydrogen gas, and for example, a turbine may be used as the expansion means.
[0051] In the above embodiment, an example was described in which liquefied hydrogen stored in the storage tank 4 is loaded onto the transport ship 100. However, the destination for loading and unloading the liquefied hydrogen can be any carrier that transports liquefied hydrogen, such as a transport vehicle like a tank truck.
[0052] (4) Summary The embodiments and their modifications include the following disclosures.
[0053] A liquefied hydrogen facility according to one aspect of the present disclosure comprises a liquefier for cooling and liquefying hydrogen gas, a storage tank for storing the liquefied hydrogen liquefied by the liquefier, a liquefied hydrogen supply line connecting the liquefier and the storage tank, a sub-tank capable of storing hydrogen gas at a pressure higher than the pressure of the gas phase of the storage tank, a branch line connecting the liquefier and the sub-tank, and a cooling line connecting a cool-down target, which is subject to pre-cooling before the liquefied hydrogen is supplied, to the sub-tank.
[0054] According to this disclosure, by introducing liquefied hydrogen discharged from a liquefier into a sub-tank via a branch line and vaporizing it, relatively high-pressure and low-temperature hydrogen gas can be stored in the sub-tank. Then, by supplying this hydrogen gas to the object to be cooled down, the object to be cooled down can be efficiently pre-cooled.
[0055] Preferably, the liquefier includes a cooler for cooling the raw hydrogen gas and an expansion valve for expanding and liquefying the hydrogen gas cooled by the cooler. The branch line connects the outlet of the expansion valve to the sub-tank.
[0056] In this embodiment, sufficiently cold liquefied hydrogen discharged from the expansion valve can be vaporized and introduced into the sub-tank, thereby keeping the temperature of the hydrogen gas accumulated in the sub-tank low. Furthermore, by adjusting the opening of the expansion valve, the depressurizing effect of the expansion valve can be suppressed, allowing the hydrogen gas pressure in the sub-tank to be set higher. In other words, in this embodiment, relatively high-pressure and low-temperature hydrogen gas suitable for pre-cooling can be accumulated in the sub-tank.
[0057] If the liquefaction includes a cooler for cooling the raw hydrogen gas and an expansion valve for expanding and liquefying the hydrogen gas cooled by the cooler, the branch line may connect the intermediate section between the cooler and the expansion valve to the sub-tank.
[0058] In this embodiment, the internal pressure of the sub-tank can be set sufficiently high by utilizing the hydrogen gas, which is under sufficiently high pressure before being expanded (liquefied) by the expansion valve of the liquefier. Therefore, the object to be cooled can be efficiently cooled by supplying it with hydrogen gas under sufficiently high pressure.
[0059] In the above embodiment, more preferably, the liquefied hydrogen equipment further comprises a pressure reducing valve installed in the middle of the branch line.
[0060] In this embodiment, the high-pressure hydrogen gas discharged from the intermediate section between the cooler and the expansion valve can be appropriately depressurized by a pressure reducing valve before being introduced into the sub-tank. This eliminates the need to excessively increase the pressure resistance (strength) of the sub-tank, allowing for rational and efficient cooling of the object to be cooled down.
[0061] Preferably, the liquefied hydrogen equipment further includes a recirculation line that branches off from the cooling line and connects to the upstream side of the liquefaction unit.
[0062] In this embodiment, during phases where pre-cooling is not performed, the hydrogen gas in the sub-tank can be reliquefied in the liquefier for effective utilization. For example, the gas-liquid two-phase fluid generated when the liquefier is started or stopped can be vaporized in the sub-tank and then returned to the liquefier for reliquefaction. This prevents the gas-liquid two-phase fluid from being introduced into the storage tank while ensuring efficient use of hydrogen. [Explanation of symbols]
[0063] 1. Liquefied hydrogen equipment 3. Liquefied machine 4 Storage tanks 4a Gas phase section 5 Sub-tank 12. Liquefied hydrogen supply line 13. Loading / unloading line (subject to cool-down) 15 Branch Line 16 Cooling lines 17 Recirculation Line 19. Relay Line (Relay Section) 31 Cooler 32 Expansion valve 40 Pressure Reducing Valve
Claims
1. A liquefaction machine that cools and liquefies hydrogen gas, A storage tank for storing the liquefied hydrogen liquefied by the liquefier, A liquefied hydrogen supply line connecting the liquefier and the storage tank, A sub-tank capable of storing hydrogen gas at a pressure higher than the pressure in the gas phase of the aforementioned storage tank, A branch line connecting the liquefier and the sub-tank, A liquefied hydrogen facility comprising a cooling line connecting a cool-down target, which is subject to pre-cooling before the flow of liquefied hydrogen, to the sub-tank.
2. In the liquefied hydrogen equipment according to claim 1, The liquefier includes a cooler for cooling the raw hydrogen gas and an expansion valve for expanding and liquefying the hydrogen gas cooled by the cooler. The aforementioned branch line connects the outlet of the expansion valve to the sub-tank, and is part of a liquefied hydrogen facility.
3. In the liquefied hydrogen equipment according to claim 1, The liquefier includes a cooler for cooling the raw hydrogen gas and an expansion valve for expanding and liquefying the hydrogen gas cooled by the cooler. The aforementioned branch line connects the intermediate section between the cooler and the expansion valve to the sub-tank, and is part of a liquefied hydrogen facility.
4. In the liquefied hydrogen equipment according to claim 3, A liquefied hydrogen facility further equipped with a pressure reducing valve installed in the middle of the aforementioned branch line.
5. In the liquefied hydrogen equipment according to any one of claims 1 to 4, A liquefied hydrogen facility further comprising a recirculation line that branches off from the aforementioned cooling line and connects to the upstream side of the liquefaction unit.