HYDROGEN LIQUEFACTION SYSTEM AND HYDROGEN LIQUEFACTION METHOD

The present disclosure relates to a hydrogen liquefaction system and hydrogen liquefaction method capable of increasing a hydrogen liquefaction amount through a pre-cooling process, and may comprise a hydrogen pipe, where gaseous hydrogen is introduced at a front end, heat exchange occurs in a heat exchange section leading to liquefaction of gaseous hydrogen into liquid hydrogen, and liquefied liquid hydrogen can be discharged at a rear end; a pre-cooling device formed between the front end of the hydrogen pipe and the heat exchange section, pre-cooling gaseous hydrogen; and a cooling cycle device, which is in thermal contact with the heat exchange section of the hydrogen pipe so as to perform heat exchange with the heat exchange section of the hydrogen pipe such that pre-cooled gaseous hydrogen can be liquefied into liquid hydrogen.

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Description
CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims the benefit of and priority to U.S. Provisional Application Ser. No. 63/454,150, filed on Mar. 23, 2023, the entire contents of which is incorporated herein by reference.

BACKGROUND 1. Field of the Invention

The present disclosure relates to a hydrogen liquefaction system and hydrogen liquefaction method, and more particularly, to a hydrogen liquefaction system and hydrogen liquefaction method capable of increasing a hydrogen liquefaction amount through a pre-cooling process.

2. Description of the Related Art

Liquid hydrogen offering increased storage density compared to high-pressure gaseous hydrogen, is experiencing growing demand as a replacement fuel for vehicles that currently use high-pressure gaseous hydrogen. In particular, liquid hydrogen is widely used in the aerospace industry as a propellant for rockets, and is expected to be widely used in trucks, buses, ships, and aircraft in the future.

Such liquid hydrogen is produced in large-scale plants and is typically sold only to users with long-term supply agreements. Therefore, even though using of liquid hydrogen is expected to grow, its availability for small-scale users remains limited.

The present disclosure is to resolve various problems including the above problem, and has a purpose of providing a hydrogen liquefaction system and hydrogen liquefaction method capable of increasing a hydrogen liquefaction amount and reducing an equipment size through a pre-cooling process. However, these problems are exemplary, and a scope of the present disclosure is not limited thereto.

SUMMARY

The hydrogen liquefaction system according to one aspect of the present disclosure to resolve the above problems may comprise a hydrogen pipe, where gaseous hydrogen is introduced at a front end, heat exchange occurs in a heat exchange section leading to liquefaction of gaseous hydrogen into liquid hydrogen, and liquefied liquid hydrogen can be discharged at a rear end; a pre-cooling device formed between the front end of the hydrogen pipe and the heat exchange section, pre-cooling gaseous hydrogen; and a cooling cycle device, which is in thermal contact with the heat exchange section of the hydrogen pipe so as to perform heat exchange with the heat exchange section of the hydrogen pipe such that pre-cooled gaseous hydrogen can be liquefied into liquid hydrogen.

Additionally, according to one embodiment of the present disclosure, the pre-cooling device may use low-temperature liquid nitrogen or latent heat that is generated when liquid nitrogen is vaporized into gaseous nitrogen to pre-cool gaseous hydrogen.

Additionally, according to one embodiment of the present disclosure, the pre-cooling device may be in thermal contact with the hydrogen pipe so as to perform heat exchange with the hydrogen pipe, having a liquid nitrogen supply pipe on one side, and have a gaseous nitrogen discharge pipe on other side.

Additionally, according to one embodiment of the present disclosure, the pre-cooling device may include: a heat exchange tank formed to surround the hydrogen pipe so as to perform heat exchange with the hydrogen pipe, being formed with an accommodating space therein so as to accommodate liquid nitrogen; a liquid nitrogen supply pipe formed in a lower part of the heat exchange tank, supplying liquid nitrogen to the heat exchange tank; and a gaseous nitrogen discharge pipe formed in an upper part of the heat exchange tank, discharging gaseous nitrogen that is vaporized from liquid nitrogen which has been accommodated in the heat exchange tank.

Additionally, according to the present disclosure, the heat exchange tank may include: an internal tank formed therein; an external tank formed to surround the internal tank so as to be spaced apart from the internal tank; and an insulating material formed between the internal tank and the external tank.

Additionally, according to one embodiment of the present disclosure, the hydrogen pipe may be formed with a bent part that is at least partially bent to increase a thermal contact area that is in contact with liquid nitrogen.

Additionally, according to one embodiment of the present disclosure, the pre-cooling device may further include: a first valve formed in the liquid nitrogen supply pipe so as to regulate a supply amount of liquid nitrogen; and a second valve formed in the gaseous nitrogen discharge pipe so as to regulate a discharge amount of gaseous nitrogen.

Additionally, according to one embodiment of the present disclosure, the pre-cooling device may further include: a level detecting sensor that detects a level of liquid nitrogen that is accommodated in the heat exchange tank; and a controller that receives a level signal from the level detecting sensor and applies a control signal to the first valve or the second valve.

Additionally, according to one embodiment of the present disclosure, the pre-cooling device may further include a temperature sensor that measures temperature of the heat exchange tank; and the controller may receive a temperature signal from the temperature sensor and apply a control signal to the first valve or the second valve.

Additionally, according to one embodiment of the present disclosure, the gaseous nitrogen discharge pipe may be formed to surround at least a portion of the hydrogen pipe so as to perform heat exchange with the hydrogen pipe, being formed in a double pipe shape together with the hydrogen pipe.

Additionally, according to one embodiment of the present disclosure, the pre-cooling device may further include a pressure regulator that regulates internal pressure of the heat exchange tank.

Additionally, according to one embodiment of the present disclosure, the pressure regulator may be a vacuum pressure forming device that regulates an internal vacuum level of the heat exchange tank so as to regulate temperature of saturated nitrogen inside the heat exchange tank.

Additionally, according to one embodiment of the present disclosure, the vacuum pressure forming device may include: a vacuum line formed in an upper part of the heat exchange tank; and a vacuum pump formed in the vacuum line.

Additionally, according to one embodiment of the present disclosure, the vacuum pressure forming device may further include: a vacuum pressure measuring sensor that measures vacuum pressure of the heat exchange tank; a vacuum pressure regulation valve formed in the vacuum line; and a vacuum pressure regulation controller that receives a vacuum pressure signal from the vacuum pressure measuring sensor and applies a control signal to the vacuum pressure regulation valve.

Additionally, according to one embodiment of the present disclosure, the cooling cycle device may include: a circulating line in which helium circulates in a reverse-Brayton cycle; a compressor formed in the circulating line, compressing helium; an aftercooler formed in the circulating line, cooling compressed helium and releasing heat; and a first expander formed in the circulating line, expanding compressed helium such that temperature of helium is firstly lowered.

Additionally, according to one embodiment of the present disclosure, the cooling cycle device may include: a second expander formed in the circulating line, expanding compressed helium such that temperature of helium is secondly lowered; a first heat exchanger formed between the aftercooler and the first expander, performing heat exchange with the circulating line that enters the compressor; a second heat exchanger formed between the first expander and the second expander, performing heat exchange with the hydrogen pipe; and a third heat exchanger formed between the second expander and the second heat exchanger, performing heat exchange with the hydrogen pipe.

Additionally, according to one embodiment of the present disclosure, the cooling cycle device may further include a fourth heat exchanger formed between the first heat exchanger and the first expander, performing heat exchange with the hydrogen pipe.

Meanwhile, the hydrogen liquefaction method according to other aspect of the present disclosure for resolving the above problems may comprise (a) preparing a hydrogen pipe, where gaseous hydrogen is introduced at a front end, heat exchange occurs in a heat exchange section leading to liquefaction of gaseous hydrogen into liquid hydrogen, and liquefied liquid hydrogen can be discharged at a rear end; (b) pre-cooling gaseous hydrogen between the front end of the hydrogen pipe and the heat exchange section by using a pre-cooling device; and (c) liquefying gaseous pre-cooled hydrogen, which is pre-cooled by performing heat exchange with the heat exchange section of the hydrogen pipe by using a cooling cycle device that is in thermal contact with the heat exchange section of the hydrogen pipe, into liquid hydrogen.

Additionally, according to one embodiment of the present disclosure, (b) may include regulating an internal vacuum level of the pre-cooling device so as to regulate temperature of saturated nitrogen inside the pre-cooling device, or regulating internal temperature or a level of liquid nitrogen of the pre-cooling device by using a valve.

Meanwhile, a hydrogen liquefaction system according to another aspect of the present disclosure for resolving the above problems may comprise: a hydrogen pipe, where gaseous hydrogen is introduced at a front end, heat exchange occurs in a heat exchange section leading to liquefaction of gaseous hydrogen into liquid hydrogen, and liquefied liquid hydrogen can be discharged at a rear end; a pre-cooling device formed between the front end of the hydrogen pipe and the heat exchange section, pre-cooling gaseous hydrogen; and a cooling cycle device, which is in thermal contact with the heat exchange section of the hydrogen pipe so as to perform heat exchange with the heat exchange section of the hydrogen pipe such that pre-cooled gaseous hydrogen can be liquefied into liquid hydrogen, wherein the pre-cooling device may include: a heat exchange tank formed to surround the hydrogen pipe so as to perform heat exchange with the hydrogen pipe, being formed with an accommodating space therein so as to accommodate liquid nitrogen; a liquid nitrogen supply pipe formed in a lower part of the heat exchange tank, supplying liquid nitrogen to the heat exchange tank; a gaseous nitrogen discharge pipe formed in an upper part of the heat exchange tank, discharging gaseous nitrogen that is vaporized from liquid nitrogen which has been accommodated in the heat exchange tank; a first valve formed in the liquid nitrogen supply pipe so as to regulate a supply amount of liquid nitrogen; and a second valve formed in the gaseous nitrogen discharge pipe so as to regulate a discharge amount of gaseous nitrogen, and the cooling cycle device may include: a circulating line in which helium circulates in a reverse-Brayton cycle; a compressor formed in the circulating line, compressing helium; an aftercooler formed in the circulating line, cooling compressed helium to release heat; a first expander formed in the circulating line, expanding compressed helium such that temperature of helium is firstly lowered; a second expander formed in the circulating line, expanding compressed helium such that temperature of helium is secondly lowered; a first heat exchanger formed between the aftercooler and the first expander, performing heat exchange with the circulating line that enters the compressor; a second heat exchanger formed between the first expander and the second expander, performing heat exchange with the hydrogen pipe; and a third heat exchanger formed between the second expander and the second heat exchanger, performing heat exchange with the hydrogen pipe.

According to various embodiments of the present disclosure formed as above, there are effects of significantly increasing a hydrogen liquefaction amount by reducing refrigeration load on room temperature of a cooling cycle device through a pre-cooling device that uses liquid nitrogen, reducing an equipment size, increasing cooling efficiency by reducing pressure of the pre-cooling device into vacuum pressure to pre-cool liquid nitrogen into a supercooled state so as to regulate a liquid nitrogen level or liquid nitrogen temperature or reduce saturated vapor pressure of liquid nitrogen, and significantly improving a hydrogen liquefaction rate and hydrogen liquefaction production at cryogenic temperature by using a reverse-Brayton cycle device that uses helium as a refrigerant. However, a scope of the present disclosure is not limited by these effects.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram conceptually showing a hydrogen liquefaction system according to some embodiments of the present disclosure.

FIG. 2 is a cross-sectional diagram conceptually showing an example of a pre-cooling device of the hydrogen liquefaction system of FIG. 1.

FIG. 3 is a cross-sectional diagram conceptually showing another example of the pre-cooling device of the hydrogen liquefaction system of FIG. 1.

FIG. 4 is a plan view conceptually showing a double pipe of the pre-cooling device of FIG. 3.

FIG. 5 is a schematic diagram conceptually showing a hydrogen liquefaction system according to some other embodiments of the present disclosure.

FIG. 6 is a cross-sectional diagram conceptually showing an example of the pre-cooling device of the hydrogen liquefaction system of FIG. 5.

FIG. 7 is a cross-sectional diagram conceptually showing another example of the pre-cooling device of the hydrogen liquefaction system of FIG. 5.

FIG. 8 is a flowchart showing a hydrogen liquefaction method according to some embodiments of the present disclosure.

 DETAILED DESCRIPTION

Hereinafter, various preferred embodiments of the present disclosure will be described in detail with reference to the appended drawings.

The embodiments of the present disclosure are provided to more completely explain the present disclosure to those skilled in the art, and the following embodiments can be modified into various other forms, and the scope of the present disclosure is not limited to the following embodiments. Instead, these embodiments are provided to enhance the faithfulness and completeness of the present disclosure and to fully convey the technical ideas of the present disclosure to those skilled in the art. Furthermore, the thickness and size of each layer in the drawings are exaggerated for convenience and clarity of explanation.

Terms used in the present specification are intended to describe a specific embodiment, and are not intended to limit the present disclosure. As used herein, a singular form may also include a plural form unless the context clearly indicates otherwise. Additionally, as used herein, terms “comprise” and/or “comprising” are intended to specify a presence of mentioned figures, numbers, steps, operations, members, elements, and/or groups thereof and are not intended to exclude a presence or addition of one or more other figures, numbers, operations, members, elements, and/or groups.

Hereinafter, embodiments of the present disclosure will now be described with reference to drawings that schematically show ideal embodiments of the present disclosure. In the drawings, variations of the depicted shape may be expected, for example, depending on manufacturing technology and/or tolerances. Accordingly, embodiments of the present disclosure should not be construed as being limited to the specific shape of the area shown in this specification, but should include, for example, changes in shape resulting from manufacturing.

FIG. 1 is a schematic diagram conceptually showing a hydrogen liquefaction system 100 according to some embodiments of the present disclosure.

First, as shown in FIG. 1, the hydrogen liquefaction system 100 according to some embodiments of the present disclosure may primarily include a hydrogen pipe 110, a pre-cooling device 20, and a cooling cycle device 30.

The hydrogen pipe 110, for example, forms a type of a hydrogen transport pathway that can transport gaseous hydrogen GH2 or liquid hydrogen LH2, and may be applied with various hydrogen lines or hydrogen transport pipes or hydrogen ducts having a sufficient strength and durability capable of withstanding high-pressure or low-temperature.

The hydrogen pipe 110, for example, as shown in FIG. 1, may be formed long in a longitudinal direction from a front end to a rear end. The hydrogen pipe 110 may be formed with the front end into which gaseous hydrogen GH2 flows, a heat exchange section 111 in which heat exchange is performed so that gaseous hydrogen GH2 is liquefied into liquid hydrogen LH2 in a middle, and the rear end through which liquefied liquid hydrogen LH2 is discharged.

However, this hydrogen pipe 110 is not limited to FIG. 1, and may be bent into various shapes or formed into various three-dimensional shapes to suit an installation environment.

Accordingly, when the hydrogen pipe 110 is used, gaseous hydrogen GH2 may flow into the front end and pass through the heat exchange section 111 in the middle, such that gaseous hydrogen GH2 can be liquefied into liquid hydrogen LH2, and then liquefied liquid hydrogen LH2 can be continuously or intermittently discharged through the rear end.

The pre-cooling device 20 may be formed between the front end of the hydrogen pipe 110 and the heat exchange section 111 so as to pre-cool gaseous hydrogen GH2 before full-scale heat exchange is performed by the cooling cycle device 30.

The pre-cooling device 20, for example, may use low-temperature liquid nitrogen LN2, or latent heat that is generated when liquid nitrogen LN2 is vaporized into gaseous nitrogen GN2, to pre-cool gaseous hydrogen GH2.

The pre-cooling device 20, more specifically, for example, as shown in FIG. 1, may include a heat exchange tank 21 that is in thermal contact with the hydrogen pipe 110 so as to perform heat exchange with the hydrogen pipe 110; a liquid nitrogen supply pipe 22 formed on one side of the heat exchange tank 21; and a gaseous nitrogen discharge pipe 23 formed on the other side of the heat exchange tank 21.

Accordingly, through this pre-cooling device 20 using liquid nitrogen LN2, gaseous hydrogen GH2 can be pre-cooled in advance before full-scale heat exchange is performed by the cooling cycle device 30 such that a hydrogen liquefaction amount can be significantly increased by reducing refrigeration load on room temperature of the cooling cycle device 30.

The cooling cycle device 30 may be a device formed to be in thermal contact with the heat exchange section 111 of the hydrogen pipe 110 so as to perform heat exchange with the heat exchange section 111 of the hydrogen pipe 110 such that pre-cooled gaseous hydrogen GH2 can be liquefied into liquid hydrogen LH2.

The cooling cycle device 30, more specifically, for example, as shown in FIG. 1, may include a circulating line 31 in which helium He circulates in a reverse-Brayton cycle; a compressor 32 formed in the circulating line 31, compressing helium He; an aftercooler 33 formed in the circulating line 31, cooling compressed helium He to release heat; a first expander E1 formed in the circulating line 31, expanding compressed helium He such that temperature of helium He is firstly lowered; a second expander E2 formed in the circulating line 31, expanding compressed helium He such that temperature of helium He is secondly lowered; a first heat exchanger HX1 formed between the aftercooler 33 and the first expander E1, performing heat exchange with the circulating line 31 that enters the compressor 32; a second heat exchanger HX2 formed between the first expander E1 and the second expander E2, performing heat exchange with the hydrogen pipe 110; and a third heat exchanger HX3 formed between the second expander E2 and the second heat exchanger HX2, performing heat exchange with the hydrogen pipe 110.

Therefore, according to the cooling cycle device 30, as shown in FIG. 1, helium He circulates along the circulating line 31 passing through the compressor 32 and aftercooler 33 in a first pathway, the first heat exchanger HX1 in a second pathway, the first expander E1 in a third pathway, the second heat exchanger HX2 in a fourth pathway, the second expander E2 in a fifth pathway, the third heat exchanger HX3 in a sixth pathway, the second heat exchanger HX2 in a seventh pathway, the first heat exchanger HX1 in a eighth pathway, and the compressor 32 in the first pathway again, thereby forming a cold box using latent heat that is generated when compressed helium He expands.

Here, the hydrogen pipe 110 is pre-cooled by the pre-cooling device 20, and then each of the heat exchange sections 111 is in thermal contact with the second heat exchanger HX2 in an ‘a’ pathway and the third heat exchanger HX3 in a ‘b’ pathway so as to perform heat exchange, such that gaseous hydrogen GH2 can be liquefied into liquid hydrogen LH2.

However, this cooling cycle device 30 is not necessarily limited to FIG. 1, and may be applied with a wide variety of types and shapes of cooling cycle devices capable of liquefying gaseous hydrogen GH2 into liquid hydrogen LH2.

FIG. 2 is a cross-sectional diagram conceptually showing an example of a pre-cooling device 20 of the hydrogen liquefaction system 100 of FIG. 1.

The pre-cooling device 20, for example, may include a heat exchange tank 21 formed to surround the hydrogen pipe 110 so as to perform heat exchange with the hydrogen pipe 110, and formed with an accommodating space therein so as to accommodate liquid nitrogen LN2; a liquid nitrogen supply pipe 22 formed in a lower part of the heat exchange tank 21, supplying liquid nitrogen LN2 to the heat exchange tank 21; and a gaseous nitrogen discharge pipe 23 formed in an upper part of the heat exchange tank 21, discharging gaseous nitrogen GN2 that is vaporized from liquid nitrogen LN2 which has been accommodated in the heat exchange tank 21.

The heat exchange tank 21, for example, as shown in an enlarged portion of FIG. 2, may include an internal tank 211 formed therein; an external tank 212 formed to surround the internal tank 211 so as to be spaced apart from the internal tank 211; and an insulating material 213 formed between the internal tank 211 and the external tank 212.

The internal tank 211 and the external tank 212 may be a hollow double box-shaped structure that has sufficient strength and durability to withstand thermal deformation at cryogenic temperature and pressure differences between an interior and exterior, and the insulating material 213 may be applied with insulating foam, glass fiber, aerosol, polymer material, aluminum foil, or the like capable of insulating at cryogenic temperature.

However, the heat exchange tank 21 is not necessarily limited to FIG. 2, and may be applied with a wide variety of shapes of structures having sufficient strength and durability to withstand thermal deformation at cryogenic temperature and pressure differences between an interior and exterior.

The pre-cooling device 20, for example, as shown in FIG. 2, may further include: a first valve V1 formed in the liquid nitrogen supply pipe 22 so as to regulate a supply amount of liquid nitrogen LN2; a second valve V2 formed in the gaseous nitrogen discharge pipe 23 so as to regulate a discharge amount of gaseous nitrogen GN2; a level detecting sensor 24 that detects a level of liquid nitrogen LN2 that is accommodated in the heat exchange tank 21; and a controller 25 that receives a level signal from the level detecting sensor 24, and applies a control signal to the first valve V1 or the second valve V2.

Accordingly, for example, when a level signal from the level detecting sensor 24 indicates a low level that is lower than a reference range, the controller 25 may raise the level by applying a control signal that opens the first valve V1 or closes the second valve V2, or conversely, when a level signal from the level detecting sensor 24 indicates a high level that is higher than a reference range, the controller 25 may lower the level by applying a control signal that closes the first valve V1 or opens the second valve V2.

The pre-cooling device 20, for example, as shown in FIG. 2, may further include a temperature sensor 26 that measures temperature of the heat exchange tank 21.

Accordingly, the controller 25 may receive a temperature signal from the temperature sensor 26, and apply a control signal to the first valve V1 or the second valve V2. For example, it is possible to regulate a supply amount of liquid nitrogen LN2 in a cryogenic temperature state or regulate a discharge amount of gaseous nitrogen GN2 depending on a temperature signal applied from the temperature sensor 26.

Meanwhile, the hydrogen pipe 110 may be formed with a bent part 12 that is at least partially bent in a zigzag pattern to increase a thermal contact area that is in contact with liquid nitrogen LN2. However, this bent part 12 is not necessarily limited to FIG. 2, and may be applied with a wide variety of shapes of multi-surface structures, including branching or joining with fine pipes.

FIG. 3 is a cross-sectional diagram conceptually showing another example of a pre-cooling device 20 of the hydrogen liquefaction system 200 of FIG. 1, and FIG. 4 is a plan view conceptually showing a double pipe D of the pre-cooling device 20 of FIG. 3.

The gaseous nitrogen discharge pipe 23, for example, as shown in FIG. 3 and FIG. 4, may be formed to surround at least a portion of the hydrogen pipe 110 so as to perform heat exchange with the hydrogen pipe 110, thereby forming a double pipe D shape together with the hydrogen pipe 110.

The hydrogen pipe 110 and the gaseous nitrogen discharge pipe 23, which are in a double pipe D shape, may have a concentric double pipe structure to allow primary pre-cooling in advance for heat exchange between gaseous nitrogen GN2 that is vaporized and discharged through the gaseous nitrogen discharge pipe 23 and gaseous hydrogen GH2 that flows into the hydrogen pipe 110 in a room temperature state, thereby reducing thermal stress of the hydrogen pipe 110 in advance.

Subsequently, gaseous hydrogen GH2 passes through the bent part 12 that is bent in a zigzag pattern, and exchanges heat with liquid nitrogen LN2, thereby allowing secondary pre-cooling.

FIG. 5 is a schematic diagram conceptually showing a hydrogen liquefaction system 200 according to some other embodiments of the present disclosure.

As shown in FIG. 5, the pre-cooling device 20 of the hydrogen liquefaction system 200 according to some other embodiments of the present disclosure may further include a pressure regulator 27 that regulates internal pressure of the heat exchange tank 21.

The pressure regulator 27 may be a vacuum pressure forming device 28 that regulates an internal vacuum level of the heat exchange tank 21 so as to regulate temperature of saturated nitrogen inside the heat exchange tank 21 (see FIG. 6).

The cooling cycle device 30, for example, as shown in FIG. 5, may include a circulating line 31 in which helium He circulates in a reverse-Brayton cycle; a compressor 32 formed in the circulating line 31, compressing helium He; an aftercooler 33 formed in the circulating line 31, cooling compressed helium He to release heat; a first expander E1 formed in the circulating line 31, expanding compressed helium He such that temperature of helium He is firstly lowered; a second expander E2 formed in the circulating line 31, expanding compressed helium He such that temperature of helium He is secondly lowered; a first heat exchanger HX1 formed between the aftercooler 33 and the first expander E1, performing heat exchange with the circulating line 31 that enters the compressor 32; a second heat exchanger HX2 formed between the first expander E1 and the second expander E2, performing heat exchange with the hydrogen pipe 110; a third heat exchanger HX3 formed between the second expander E2 and the second heat exchanger HX2, performing heat exchange with the hydrogen pipe 110; and a fourth heat exchanger HX4 formed between the first heat exchanger HX1 and the first expander E1, performing heat exchange with the hydrogen pipe 110.

Therefore, according to the cooling cycle device 30, as shown in FIG. 5, helium He circulates through the compressor 32 and aftercooler 33 in a first pathway, the first heat exchanger HX1 in a second pathway, the fourth heat exchanger HX4 in a third pathway, the first expander E1 in a fourth pathway, the second heat exchanger HX2 in a fifth pathway, the second expander E2 in a sixth pathway, the third heat exchanger HX3 in a seventh pathway, the second heat exchanger HX2 in a eighth pathway, the fourth heat exchanger HX4 in a ninth pathway, the first heat exchanger HX1 in a tenth pathway, and the compressor 32 in the first pathway again, along the circulating line 31, thereby forming a cold box using latent heat that is generated when compressed helium He expands.

Here, the hydrogen pipe 110 is pre-cooled by the pre-cooling device 20 that uses a vacuum pressure forming device 28, and then each of the heat exchange sections 111 is in thermal contact with the fourth heat exchanger HX4 in an ‘a’ pathway, the second heat exchanger HX2 in a ‘b’ pathway, and the third heat exchanger HX3 in ‘c’ pathway so as to perform heat exchange, such that gaseous hydrogen GH2 can be liquefied into liquid hydrogen LH2.

FIG. 6 is a cross-sectional diagram conceptually showing an example of a pre-cooling device 20 of the hydrogen liquefaction system 200 of FIG. 5.

As shown in FIG. 5 and FIG. 6, the vacuum pressure forming device 28 of the hydrogen liquefaction system 200 according to some other embodiments of the present disclosure may include a vacuum line 281 formed in an upper part of the heat exchange tank 21; a vacuum pump 282 formed in the vacuum line 281; a vacuum pressure measuring sensor 283 that measures vacuum pressure of the heat exchange tank 21; a vacuum pressure regulation valve 284 formed in the vacuum line 281; and a vacuum pressure regulation controller 285 that receives a vacuum pressure signal from the vacuum pressure measuring sensor 283 and applies a control signal to the vacuum pressure regulation valve 284.

Accordingly, the vacuum pressure regulation controller 285 may apply a control signal to the vacuum pressure regulation valve 284 while the vacuum pump 282 is operating, and may form an interior of the heat exchange tank 21 into a vacuum state, thereby controlling temperature of saturated nitrogen so as to supercool liquid nitrogen LN2 to a lower temperature.

FIG. 7 is a cross-sectional diagram conceptually showing another example of a pre-cooling device 20 of the hydrogen liquefaction system 200 of FIG. 5.

The gaseous nitrogen discharge pipe 23, for example, as shown in FIG. 7, may be formed to surround at least a portion of the hydrogen pipe 110 so as to perform heat exchange with the hydrogen pipe 110, and be formed in a double pipe D shape together with the hydrogen pipe 110.

The hydrogen pipe 110 and the gaseous nitrogen discharge pipe 23, which are in a double pipe D shape, may have a concentric double pipe structure to allow primary pre-cooling in advance for heat exchange between gaseous nitrogen GN2 that is vaporized and discharged through the gaseous nitrogen discharge pipe 23 and gaseous hydrogen GH2 that flows into the hydrogen pipe 110 in a room temperature state, thereby reducing thermal stress of the hydrogen pipe 110 in advance.

Subsequently, gaseous hydrogen GH2 passes through the bent part 12 that is bent in a zigzag pattern, and exchanges heat with liquid nitrogen LN2, thereby allowing secondary pre-cooling.

FIG. 8 is a flowchart showing a hydrogen liquefaction method according to some embodiments of the present disclosure.

As shown in FIG. 8, the hydrogen liquefaction method according to some embodiments of the present disclosure may comprise: (a) preparing a hydrogen pipe 110, where gaseous hydrogen GH2 is introduced at a front end, heat exchange occurs in the heat exchange section 111 leading to liquefaction of gaseous hydrogen GH2 into liquid hydrogen LH2, and the liquefied liquid hydrogen LH2 can be discharged at a rear end; (b) pre-cooling gaseous hydrogen GH2 between the front end of the hydrogen pipe 110 and the heat exchange section 111 by using a pre-cooling device 20; and (c) liquefying pre-cooled gaseous hydrogen GH2 into liquid hydrogen LH2 by performing heat exchange with the heat exchange section 111 of the hydrogen pipe 110 by using a cooling cycle device 30 that is in thermal contact with the heat exchange section 111 of the hydrogen pipe 110.

For example, in (b), it is possible to regulate an internal vacuum level of the pre-cooling device 20 in order to regulate temperature of saturated nitrogen inside the pre-cooling device 20.

For example, in (b), it is possible to regulate internal temperature or a liquid nitrogen LN2 level of the pre-cooling device 20 by using valves V1, V2.

Therefore, according to the present disclosure, it is possible to significantly increase a hydrogen liquefaction amount by reducing refrigeration load on room temperature of a cooling cycle device 30 through a pre-cooling device 20 that uses liquid nitrogen LN2, reduce an equipment size, further increase cooling efficiency by reducing pressure of the pre-cooling device 20 into vacuum pressure to pre-cool liquid nitrogen into a supercooled state so as to regulate a liquid nitrogen LN2 level or liquid nitrogen LN2 temperature or reduce saturated vapor pressure of liquid nitrogen LN2, and significantly improve a hydrogen liquefaction rate and hydrogen liquefaction production at cryogenic temperature by using a reverse-Brayton cycle device that uses helium He as a refrigerant.

Although the above has shown and described various embodiments of the present disclosure, the present disclosure is not limited to the specific embodiments described above. The above-described embodiments can be variously modified and implemented by those skilled in the art to which the present disclosure pertains without departing from the gist of the present disclosure claimed in the appended claims, and these modified embodiments should not be understood separately from the technical spirit or scope of the present disclosure. Therefore, the technical scope of the present disclosure should be defined only by the appended claims.

In the embodiments disclosed herein, arrangement of illustrated components may vary depending on requirements or environment in which the disclosure is implemented. For example, some components may be omitted or some components may be integrated and implemented as one.

Claims

1. A hydrogen liquefaction system, comprising:

a hydrogen pipe, where gaseous hydrogen is introduced at a front end, heat exchange occurs in a heat exchange section leading to liquefaction of gaseous hydrogen into liquid hydrogen, and liquefied liquid hydrogen can be discharged at a rear end;
a pre-cooling device formed between the front end of the hydrogen pipe and the heat exchange section, pre-cooling gaseous hydrogen; and
a cooling cycle device, which is in thermal contact with the heat exchange section of the hydrogen pipe so as to perform heat exchange with the heat exchange section of the hydrogen pipe such that pre-cooled gaseous hydrogen can be liquefied into liquid hydrogen.

2. The hydrogen liquefaction system according to claim 1,

wherein the pre-cooling device uses low-temperature liquid nitrogen or latent heat that is generated when liquid nitrogen is vaporized into gaseous nitrogen to pre-cool gaseous hydrogen.

3. The hydrogen liquefaction system according to claim 2,

wherein the pre-cooling device is in thermal contact with the hydrogen pipe so as to perform heat exchange with the hydrogen pipe, having a liquid nitrogen supply pipe on one side and a gaseous nitrogen discharge pipe on other side.

4. The hydrogen liquefaction system according to claim 2,

wherein the pre-cooling device includes:
a heat exchange tank formed to surround the hydrogen pipe so as to perform heat exchange with the hydrogen pipe, being formed with an accommodating space therein so as to accommodate liquid nitrogen;
a liquid nitrogen supply pipe formed in a lower part of the heat exchange tank, supplying liquid nitrogen to the heat exchange tank; and
a gaseous nitrogen discharge pipe formed in an upper part of the heat exchange tank, discharging gaseous nitrogen that is vaporized from liquid nitrogen which has been accommodated in the heat exchange tank.

5. The hydrogen liquefaction system according to claim 4,

wherein the heat exchange tank includes:
an internal tank formed therein;
an external tank formed to surround the internal tank so as to be spaced apart from the internal tank; and
an insulating material formed between the internal tank and the external tank.

6. The hydrogen liquefaction system according to claim 4,

wherein the hydrogen pipe is formed with a bent part that is at least partially bent to increase a thermal contact area that is in contact with liquid nitrogen.

7. The hydrogen liquefaction system according to claim 4,

wherein the pre-cooling device further includes:
a first valve formed in the liquid nitrogen supply pipe so as to regulate a supply amount of liquid nitrogen; and
a second valve formed in the gaseous nitrogen discharge pipe so as to regulate a discharge amount of gaseous nitrogen.

8. The hydrogen liquefaction system according to claim 7,

wherein the pre-cooling device further includes:
a level detecting sensor that detects a level of liquid nitrogen that is accommodated in the heat exchange tank; and
a controller that receives a level signal from the level detecting sensor and applies a control signal to the first valve or the second valve.

9. The hydrogen liquefaction system according to claim 8,

wherein the pre-cooling device further includes a temperature sensor that measures temperature of the heat exchange tank; and
the controller receives a temperature signal from the temperature sensor and applies a control signal to the first valve or the second valve.

10. The hydrogen liquefaction system according to claim 4,

wherein the gaseous nitrogen discharge pipe is formed to surround at least a portion of the hydrogen pipe so as to perform heat exchange with the hydrogen pipe, being formed in a double pipe shape together with the hydrogen pipe.

11. The hydrogen liquefaction system according to claim 4,

wherein the pre-cooling device further includes a pressure regulator that regulates internal pressure of the heat exchange tank.

12. The hydrogen liquefaction system according to claim 11,

wherein the pressure regulator is a vacuum pressure forming device that regulates an internal vacuum level of the heat exchange tank so as to regulate temperature of saturated nitrogen inside the heat exchange tank.

13. The hydrogen liquefaction system according to claim 12,

wherein the vacuum pressure forming device includes:
a vacuum line formed in an upper part of the heat exchange tank; and
a vacuum pump formed in the vacuum line.

14. The hydrogen liquefaction system according to claim 13,

wherein the vacuum pressure forming device further includes:
a vacuum pressure measuring sensor that measures vacuum pressure of the heat exchange tank;
a vacuum pressure regulation valve formed in the vacuum line; and
a vacuum pressure regulation controller that receives a vacuum pressure signal from the vacuum pressure measuring sensor and applies a control signal to the vacuum pressure regulation valve.

15. The hydrogen liquefaction system according to claim 1,

wherein the cooling cycle device includes:
a circulating line in which helium circulates in a reverse-Brayton cycle;
a compressor formed in the circulating line, compressing helium;
an aftercooler formed in the circulating line, cooling compressed helium and releasing heat; and
a first expander formed in the circulating line, expanding compressed helium such that temperature of helium is firstly lowered.

16. The hydrogen liquefaction system according to claim 15,

wherein the cooling cycle device includes:
a second expander formed in the circulating line, expanding compressed helium such that temperature of helium is secondly lowered;
a first heat exchanger formed between the aftercooler and the first expander, performing heat exchange with the circulating line that enters the compressor;
a second heat exchanger formed between the first expander and the second expander, performing heat exchange with the hydrogen pipe; and
a third heat exchanger formed between the second expander and the second heat exchanger, performing heat exchange with the hydrogen pipe.

17. The hydrogen liquefaction system according to claim 16,

wherein the cooling cycle device further includes:
a fourth heat exchanger formed between the first heat exchanger and the first expander, performing heat exchange with the hydrogen pipe.

18. A hydrogen liquefaction method, comprising:

(a) preparing a hydrogen pipe, where gaseous hydrogen is introduced at a front end, heat exchange occurs in a heat exchange section leading to liquefaction of gaseous hydrogen into liquid hydrogen, and liquefied liquid hydrogen can be discharged at a rear end;
(b) pre-cooling gaseous hydrogen between the front end of the hydrogen pipe and the heat exchange section by using a pre-cooling device; and
(c) liquefying gaseous pre-cooled hydrogen, which is pre-cooled by performing heat exchange with the heat exchange section of the hydrogen pipe by using a cooling cycle device that is in thermal contact with the heat exchange section of the hydrogen pipe, into liquid hydrogen.

19. The hydrogen liquefaction method according to claim 18,

wherein (b) includes regulating an internal vacuum level of the pre-cooling device so as to regulate temperature of saturated nitrogen inside the pre-cooling device, or regulating internal temperature or a level of liquid nitrogen of the pre-cooling device by using a valve.

20. A hydrogen liquefaction system, comprising:

a hydrogen pipe, where gaseous hydrogen is introduced at a front end, heat exchange occurs in a heat exchange section leading to liquefaction of gaseous hydrogen into liquid hydrogen, and liquefied liquid hydrogen can be discharged at a rear end;
a pre-cooling device formed between the front end of the hydrogen pipe and the heat exchange section, pre-cooling gaseous hydrogen; and
a cooling cycle device, which is in thermal contact with the heat exchange section of the hydrogen pipe so as to perform heat exchange with the heat exchange section of the hydrogen pipe such that pre-cooled gaseous hydrogen can be liquefied into liquid hydrogen,
wherein the pre-cooling device includes:
a heat exchange tank formed to surround the hydrogen pipe so as to perform heat exchange with the hydrogen pipe, being formed with an accommodating space therein so as to accommodate liquid nitrogen;
a liquid nitrogen supply pipe formed in a lower part of the heat exchange tank, supplying liquid nitrogen to the heat exchange tank;
a gaseous nitrogen discharge pipe formed in an upper part of the heat exchange tank, discharging gaseous nitrogen that is vaporized from liquid nitrogen which has been accommodated in the heat exchange tank;
a first valve formed in the liquid nitrogen supply pipe so as to regulate a supply amount of liquid nitrogen; and
a second valve formed in the gaseous nitrogen discharge pipe so as to regulate a discharge amount of gaseous nitrogen,
and the cooling cycle device includes:
a circulating line in which helium circulates in a reverse-Brayton cycle;
a compressor formed in the circulating line, compressing helium;
an aftercooler formed in the circulating line, cooling compressed helium to release heat;
a first expander formed in the circulating line, expanding compressed helium such that temperature of helium is firstly lowered;
a second expander formed in the circulating line, expanding compressed helium such that temperature of helium is secondly lowered;
a first heat exchanger formed between the aftercooler and the first expander, performing heat exchange with the circulating line that enters the compressor;
a second heat exchanger formed between the first expander and the second expander, performing heat exchange with the hydrogen pipe; and
a third heat exchanger formed between the second expander and the second heat exchanger, performing heat exchange with the hydrogen pipe.
Patent History
Publication number: 20240318908
Type: Application
Filed: Jan 5, 2024
Publication Date: Sep 26, 2024
Inventors: JONG H. BAIK (Titusville, FL), HO-MYUNG CHANG (Seoul), HYUNG JIN KIM (Gyeonggi-do)
Application Number: 18/405,776
Classifications
International Classification: F25J 1/02 (20060101); F25J 1/00 (20060101);