High-efficiency hydrogen liquefaction system and hydrogen liquefaction process using same

Abstract

The present invention relates to a high-efficiency hydrogen liquefaction system comprising: a cooling cycle unit that includes a pre-cooling cycle for circulating a pre-cooling refrigerant and a liquefaction cycle for circulating a liquefaction refrigerant; a cooling line unit through which an object to be cooled by the cooling cycle unit passes; and a heat exchange unit for exchanging heat between the cooling cycle unit and the cooling line unit, wherein the liquefaction cycle includes: a main liquefaction line; a first liquefaction line, which branches off from a first liquefaction branch point of the main liquefaction line so as to be joined to a first liquefaction joining point of the main liquefaction line; and a second liquefaction line, which branches off from a second liquefaction branch point of the main liquefaction line so as to be joined to a second liquefaction joining point of the main liquefaction line, the second liquefaction branch point that can be positioned further downstream than the first liquefaction branch point.

Description

High-efficiency hydrogen liquefaction system and hydrogen liquefaction process using the same

[0001] [Cross-citation with related applications]

[0002] This invention claims the benefit of priority from Korean Patent Application No. 10-2024-0095306, filed July 18, 2024, the entire contents of which are incorporated herein by reference.

[0003] [Technical Field]

[0004] The present invention relates to a high-efficiency hydrogen liquefaction system and a hydrogen liquefaction process using the same.

[0005] With the recent expansion of hydrogen fuel use across various fields, the need for large-scale hydrogen liquefaction processes is emerging. Unlike unstable gaseous hydrogen, liquid hydrogen can be stored at atmospheric pressure and has a relatively small volume, offering superior safety and cost-effectiveness relative to its area.

[0006] Figure 1 is a schematic diagram illustrating the flow of an exemplary hydrogen liquefaction process. Figure 2 is a schematic diagram illustrating the temperature range of an exemplary hydrogen liquefaction process. Figure 3 is a pressure-temperature graph illustrating the Joule-Thomson coefficients of each substance.

[0007] The hydrogen liquefaction process, as illustrated, can be broadly divided into pre-cooling and liquefaction stages. The pre-treatment steps can be performed sequentially, and the pre-cooling process for the pre-treated hydrogen can be performed.

[0008] The gaseous hydrogen is cooled to an appropriate temperature through a pre-cooling process. The appropriate temperature here refers to a condition suitable for the subsequent liquefaction process, and can be selected by referring to the pressure-temperature graph based on the Joule-Thomson coefficient in Figure 3. In Figure 3, the horizontal axis represents pressure in atmospheric pressure (atm), and the vertical axis represents temperature in Kelvin (K), the absolute temperature.

[0009] Referring to the graph in Fig. 3, there are sections where the Joule-Thomson coefficient is positive and sections where it is negative. The Joule-Thomson coefficient represents the value of the temperature change according to the pressure change at the same enthalpy. In other words, if the Joule-Thomson coefficient is positive, the temperature decreases according to the pressure decrease when the gas expands. Therefore, in order to liquefy hydrogen by reducing the temperature through Joule-Thomson expansion, the gaseous hydrogen must be placed in the section where the Joule-Thomson coefficient is positive as shown in the graph, and this preliminary state before liquefaction is achieved through pressurization and precooling. For example, precooling can be performed to 80 K (-193 °C), which is a temperature in the section where the Joule-Thomson coefficient of hydrogen is positive, by using the heat of vaporization of liquid nitrogen.

[0010] In the main refrigeration, pre-cooled hydrogen can be liquefied by cooling it to 20K (-253℃) using hydrogen and helium. Joule-Thomson expansion can be achieved in the main refrigeration using a Joule-Thomson valve. In other words, cooling to 20K (-253℃) is required for liquefaction at atmospheric pressure.

[0011] Therefore, in order to improve the efficiency of the entire hydrogen liquefaction process, it is necessary to optimize the pre-cooling process and main cooling process with an efficient configuration.

[0012] The object of the present invention is to provide a high-efficiency hydrogen liquefaction system and a hydrogen liquefaction process using the same by efficiently configuring a pre-cooling process and a main cooling process.

[0013] In one example, a high-efficiency hydrogen liquefaction system includes a cooling cycle section including a pre-cooling cycle configured to circulate a pre-cooled refrigerant and a main cooling cycle configured to circulate a main cooling refrigerant, a cooling line section through which a cooling object to be cooled by the cooling cycle section passes, and a heat exchange section for heat-exchanging the cooling cycle section and the cooling line section, wherein the main cooling cycle includes a main main cooling line, a first main cooling line branched from a first main cooling branch point of the main main cooling line and joining a first main cooling junction point which is a point of the main main cooling line, and a second main cooling line branched from a second main cooling branch point of the main main cooling line and joining a second main cooling junction point which is a point of the main main cooling line or the first main cooling line, wherein the second main cooling branch point may be located downstream compared to the first main cooling branch point.

[0014] In another example, the main refrigeration cycle may further include a main refrigeration expansion valve disposed downstream of the second main refrigeration branch point in the main refrigeration line and a main refrigeration compressor disposed downstream of the main refrigeration expansion valve.

[0015] In another example, the main cooling cycle may further include a first main cooling expander disposed in the first main cooling line and a second main cooling expander disposed in the second main cooling line.

[0016] In another example, the main refrigeration cycle may further include a first main refrigeration compressor disposed in the first main refrigeration line but downstream of the first main refrigeration expander, and a second main refrigeration compressor disposed in the second main refrigeration line but downstream of the second main refrigeration expander.

[0017] In another example, the main refrigeration cycle may further include a first main refrigeration compressor disposed in the main main refrigeration line but downstream of the main main refrigeration compressor, and a second main refrigeration compressor disposed in the main main refrigeration line but downstream of the main main refrigeration compressor and upstream of the first main refrigeration compressor.

[0018] In another example, the precooling cycle may include a first gas-liquid separator configured to separate gas-liquid from an incoming precooled refrigerant, a first precooling line configured to pass a gaseous precooled refrigerant discharged from the first gas-liquid separator, a second precooling line configured to pass a liquid precooled refrigerant discharged from the first gas-liquid separator, a connection precooling line connected to the first precooling line and the second precooling line, a second gas-liquid separator configured to separate gas-liquid from a refrigerant introduced from the connection precooling line, a third precooling line configured to pass a gaseous precooled refrigerant discharged from the second gas-liquid separator and connected to the first gas-liquid separator, and a fourth precooling line configured to pass a liquid precooled refrigerant discharged from the second gas-liquid separator and connected to the first gas-liquid separator.

[0019] In another example, the precooling cycle may further include a first precooling expansion valve disposed in the first precooling line, a first precooling compressor disposed in the first precooling line but downstream of the first precooling expansion valve, a second precooling expansion valve disposed in the second precooling line, and a second precooling compressor disposed in the second precooling line but downstream of the second precooling expansion valve.

[0020] In another example, the pre-cooling cycle may further include a third pre-cooling compressor disposed in the third pre-cooling line and a pre-cooling pump disposed in the fourth pre-cooling line to pump the pre-cooled refrigerant in the fourth pre-cooling line toward the first gas-liquid separator.

[0021] In another example, the heat exchanger may include a first heat exchanger configured to heat-exchange the pre-cooling cycle and the main cooling cycle with the cooling line section, and a second heat exchanger configured to heat-exchange the pre-cooling cycle and the main cooling cycle with the cooling line section, but passing downstream of a point where the first heat exchanger passes among the cooling line sections.

[0022] In another example, the first heat exchanger may be arranged so that the first pre-cooling line and the second pre-cooling line pass through it, and the second heat exchanger may be arranged so that the first pre-cooling line passes through it.

[0023] In another example, the heat exchanger may include a third heat exchanger configured to exchange heat between the main cooling cycle and the cooling line section, a fourth heat exchanger configured to exchange heat between the main cooling cycle and the cooling line section, but passing downstream of a point where the third heat exchanger passes in the cooling line section, a fifth heat exchanger configured to exchange heat between the main cooling cycle and the cooling line section, but passing downstream of a point where the fourth heat exchanger passes in the cooling line section, and a sixth heat exchanger configured to exchange heat between the main cooling cycle and the cooling line section, but passing downstream of a point where the fifth heat exchanger passes in the cooling line section.

[0024] In another example, the third heat exchanger and the fourth heat exchanger may be arranged so that a portion of the main cooling line passes between the first cooling branch point and the second cooling branch point.

[0025] In another example, the third heat exchanger may be arranged so that the main cooling line, the first cooling line, and the second cooling line pass through it, and the fourth heat exchanger may be arranged so that the main cooling line and the second cooling line pass through it.

[0026] In another example, the fifth heat exchanger and the sixth heat exchanger may be arranged so that a portion of the main cooling line passes between the second cooling branch point and the cooling expansion valve.

[0027] In another example, the fifth heat exchanger may be arranged so that the main cooling line and the second cooling line pass through it, and the sixth heat exchanger may be arranged so that the main cooling line passes through it.

[0028] In another example, the compression ratio of the main main-cooled compressor may be greater than or equal to the compression ratios of the first main-cooled compressor and the second main-cooled compressor.

[0029] In another example, the compression ratio of the first pre-cooling compressor may be greater than the compression ratio of the second pre-cooling compressor.

[0030] In another example, the main refrigerant may include helium.

[0031] For example, a hydrogen liquefaction process includes a pre-cooling step of cooling a gaseous object to be cooled and a main cooling step of liquefying the pre-cooled gaseous object to be cooled, wherein the pre-cooling step is performed by a pre-cooling cycle, and the main cooling step is performed by a main cooling cycle, wherein the main cooling cycle includes a main main cooling line, a first main cooling line branched from a first main cooling branch point of the main main cooling line and joining a first main cooling junction point which is a point of the main main cooling line, and a second main cooling line branched from a second main cooling branch point of the main main cooling line and joining a second main cooling junction point which is a point of the main main cooling line or the first main cooling line, and the second main cooling branch point may be located downstream compared to the first main cooling branch point.

[0032] As another example, the precooling cycle of the hydrogen liquefaction process may include a first gas-liquid separator configured to separate gas-liquid from an incoming precooled refrigerant, a first precooling line configured to pass a gaseous precooled refrigerant discharged from the first gas-liquid separator, a second precooling line configured to pass a liquid-phase precooled refrigerant discharged from the first gas-liquid separator, a connection precooling line connected to the first precooling line and the second precooling line, a second gas-liquid separator configured to separate gas-liquid from a refrigerant introduced from the connection precooling line, a third precooling line configured to pass a gaseous precooled refrigerant discharged from the second gas-liquid separator and connected to the first gas-liquid separator, and a fourth precooling line configured to pass a liquid-phase precooled refrigerant discharged from the second gas-liquid separator and connected to the first gas-liquid separator.

[0033] According to the present invention, a highly efficient hydrogen liquefaction system and a hydrogen liquefaction process using the same can be obtained by efficiently configuring a pre-cooling process and a main cooling process.

[0034] Figure 1 is a conceptual diagram showing the flow of an exemplary hydrogen liquefaction process.

[0035] Figure 2 is a conceptual diagram showing the temperature range of an exemplary hydrogen liquefaction process.

[0036] Figure 3 is a pressure-temperature graph showing the Joule-Thomson coefficient of each material.

[0037] Figure 4 is a conceptual diagram showing a high-efficiency hydrogen liquefaction system according to one embodiment of the present invention.

[0038] Figures 5 to 7 are drawings illustrating a high-efficiency liquefaction system according to another embodiment.

[0039] Hereinafter, some embodiments of the present invention will be described in detail with reference to exemplary drawings. When designating components in each drawing, identical components are given the same reference numerals, wherever possible, even if they appear in different drawings. Furthermore, when describing embodiments of the present invention, detailed descriptions of known components or functions will be omitted if they are deemed to hinder understanding of the embodiments of the present invention.

[0040] Additionally, terms such as first, second, A, B, (a), (b), etc. may be used to describe components of embodiments of the present invention. These terms are only intended to distinguish the components from other components, and the nature, order, or sequence of the components are not limited by the terms. When it is described that a component is "connected," "coupled," or "connected" to another component, it should be understood that the component may be directly connected or connected to the other component, but another component may also be "connected," "coupled," or "connected" between each component.

[0041] Meanwhile, the terms "upstream" and "downstream" in this specification may refer to the direction of fluid flow. For example, if fluid flows from left to right, the left side may be considered upstream, and the right side may be considered downstream.

[0042] Basic structure of a high-efficiency hydrogen liquefaction system

[0043] Figure 4 is a conceptual diagram illustrating a high-efficiency hydrogen liquefaction system according to one embodiment of the present invention. The high-efficiency hydrogen liquefaction system according to one embodiment of the present invention may include a cooling cycle unit (10), a cooling line unit (20), and a heat exchange unit (30). The cooling cycle unit (10) may include a pre-cooling cycle (100) and a main cooling cycle (200). In the specification of the present invention, a cycle may mean a closed circuit that undergoes compression, condensation, expansion, and evaporation processes. The evaporation and condensation processes may occur by a heat exchange unit (30) described below.

[0044] The pre-cooling cycle (100) may be configured to circulate a pre-cooling refrigerant. For example, the pre-cooling refrigerant may be a mixed refrigerant containing at least one of nitrogen, C1 (methane), C2 (ethane), C3 (propane), or C4 (butane), or a combination thereof.

[0045] The main cooling cycle (200) may be configured to circulate a main cooling refrigerant. For example, the main cooling refrigerant may be hydrogen. The main cooling refrigerant may further include helium. While the main cooling discharge temperature is limited by the minimum temperature difference condition of the heat exchanger when hydrogen alone is used as the main cooling refrigerant, adding helium to the main cooling refrigerant has the advantage of allowing a lower temperature to be reached during expansion, thereby lowering the final cooling temperature.

[0046] The cooling line section (20) may be a section through which a cooling target to be cooled by the cooling cycle section (10) passes. The cooling target may be hydrogen. The specification of the present invention describes that gaseous hydrogen flows into the cooling line section (20) and is liquefied and discharged. However, if it is a gaseous substance, a substance other than hydrogen may be applied and liquefied, and the cooling target is not limited to hydrogen.

[0047] The cooling line section (20) may include a cooling line (21). The cooling line (21) may be a line through which gaseous hydrogen may flow. In the present invention, the term "line" may refer to a structure that allows fluid to flow through its interior. For example, the line may have a pipe shape. However, even if it is not a pipe, it may be used as a line as long as fluid can flow through its interior.

[0048] The cooling line section (20) may include a cooling expansion valve (22). For example, the cooling expansion valve (22) may be a Joule-Thomson expansion valve for ultimately liquefying hydrogen cooled by the heat exchange section (30) by Joule-Thomson expansion. To increase expansion efficiency, the cooling expansion valve (22) may further include an expander for isentropically expanding hydrogen in the cooling line, and may be formed by a combination of the expansion valve and the expander. The expander may lower the temperature of the hydrogen and, incidentally, generate power from the expansion of the hydrogen.

[0049] The cooling line section (20) may include a cooling gas-liquid separator (23). The cooling gas-liquid separator (23) may be configured to separate hydrogen passing through the expansion valve into gas and liquid to ultimately obtain liquefied hydrogen.

[0050] The heat exchange unit (30) can exchange heat between the cooling cycle unit (10) and the cooling line unit (20). The heat exchange unit (30) can perform a heat exchange process in the cycle. For example, the heat exchange unit (30) can perform an evaporation process during the cycle. Additionally, the heat exchange unit (30) can perform a condensation process during the cycle. The heat exchange unit (30) can liquefy hydrogen passing through the cooling line unit (20). The liquefied hydrogen can be discharged through the cooling line (21).

[0051] The heat exchange unit (30) may include a plurality of heat exchangers and a plurality of conversion modules (30'). The conversion module (30') may be placed in some of the plurality of heat exchangers. In the conversion module (30'), ortho-para conversion, which converts ortho-hydrogen into para-hydrogen by cooling and a catalyst, may occur. In the conversion module (30'), cooling or condensation of hydrogen passing through a cooling line may occur.

[0052] Pre-cooling cycle (100)

[0053] The pre-cooling cycle (100) may include a first gas-liquid separator (110), a first pre-cooling line (120), a second pre-cooling line (130), and a connecting pre-cooling line (140). The first gas-liquid separator (110) may be provided to separate the introduced pre-cooled refrigerant into gas and liquid. The first pre-cooling line (120) may be provided to allow the gaseous pre-cooled refrigerant discharged from the first gas-liquid separator (110) to pass therethrough. The second pre-cooling line (130) may be provided to allow the liquid pre-cooled refrigerant discharged from the first gas-liquid separator (110) to pass therethrough. The connecting pre-cooling line (140) may be connected to the first pre-cooling line (120) and the second pre-cooling line (130).

[0054] For example, a pre-cooling mixer (141) may be arranged in the connecting pre-cooling line (140). The pre-cooling mixer (141) may mix pre-cooling refrigerants flowing from the first pre-cooling line (120) and the second pre-cooling line (130). This pre-cooling mixer (141) may be a conventional mixer. As another example, the pre-cooling mixer (141) may not be a separate mixer, but may be a connecting structure between the first pre-cooling line (120) and the second pre-cooling line (130), i.e., a structure that is interconnected to induce mixing of the pre-cooling refrigerants of each line.

[0055] The pre-cooling cycle (100) may further include a second gas-liquid separator (150), a third pre-cooling line (160), and a fourth pre-cooling line (170). The second gas-liquid separator (150) may be provided to separate the refrigerant introduced from the connection pre-cooling line (140) into gas and liquid. The third pre-cooling line (160) is provided to allow the gaseous pre-cooling refrigerant discharged from the second gas-liquid separator (150) to pass through it, and may be connected to the first gas-liquid separator (110). The fourth pre-cooling line (170) is provided to allow the liquid pre-cooling refrigerant discharged from the second gas-liquid separator (150) to pass through it, and may be connected to the first gas-liquid separator (110).

[0056] The pre-cooling cycle (100) may include a first pre-cooling expansion valve (121), a first pre-cooling compressor (122), a second pre-cooling expansion valve (131), and a second pre-cooling compressor (132).

[0057] The first pre-cooling expansion valve (121) may be arranged in the first pre-cooling line (120) to expand the pre-cooling refrigerant in the gas phase discharged from the first gas-liquid separator (110). The first pre-cooling compressor (122) may be arranged to compress the pre-cooling refrigerant of the first pre-cooling line (120) that has undergone cooling through the heat exchange unit (30).

[0058] A second pre-cooling expansion valve (131) may be arranged in the second pre-cooling line (130) to expand the liquid pre-cooling refrigerant discharged from the first gas-liquid separator (110). A second pre-cooling compressor (132) may be arranged to compress the pre-cooling refrigerant of the second pre-cooling line (130) that has undergone cooling through the heat exchange unit (30).

[0059] The precooling cycle (100) may further include a third precooling compressor (161) and a precooling pump (171). The third precooling compressor (161) may be arranged in the third precooling line (160). The third precooling compressor (161) may be arranged to compress the precooled refrigerant in a gaseous state discharged from the second gas-liquid separator (150). An aftercooler (162) may be arranged downstream of the third precooling compressor (161). However, it should be understood that the aftercooler (162) may also be arranged downstream of all other compressors described above and below.

[0060] A pre-cooling pump (171) may be arranged in the fourth pre-cooling line (170) to pump the liquid pre-cooling refrigerant in the fourth pre-cooling line (170) toward the first gas-liquid separator (110).

[0061] Main cooling cycle (200)

[0062] The main cooling cycle (200) may include a main main cooling line (210), a first main cooling line (220), and a second main cooling line (230).

[0063] The first main cooling line (220) can branch off from the first main cooling branch point (211) of the main main cooling line (210) and join to the first main cooling joining point of the main main cooling line (210).

[0064] The second main cooling line (230) may branch off from the second main cooling branch point (212) of the main main cooling line (210) and join the second main cooling confluence point of the main main cooling line (210). The second main cooling branch point (212) may be located downstream from the first main cooling branch point (211). For example, the first main cooling confluence point and the second main cooling confluence point may be the same point.

[0065] At this time, a main cooling mixer (213) can be placed at the main cooling junction point.

[0066] The main refrigerant mixer (213) can mix the main refrigerant flowing from at least one of the main refrigerant line (210), the first main refrigerant line (220), and the second main refrigerant line (230). The main refrigerant mixer (213) may be a conventional mixer. As another example, the main refrigerant mixer (213) may not be a separate mixer, but may be a connecting structure between the main refrigerant line (210), the first main refrigerant line (220), and the second main refrigerant line (230), i.e., a structure that is interconnected to induce mixing of the main refrigerants of each line.

[0067] However, the first main cold confluence point and the second main cold confluence point do not necessarily have to coincide, and this will be described later.

[0068] The Claude Cycle previously used in the main cooling cycle (200) has a serial structure, so all of the expansion outlet flow discharged from the first expander flows into the second expander, which has the problem of placing a load on the second compressor.

[0069] In the case of the high-efficiency hydrogen liquefaction system according to the present invention, since it has a parallel structure and a separate compression structure, the load on the compressor can be reduced by independently configuring the expansion and compression sections and flow rates according to the target cooling temperature, and the refrigerant flow rate and expander recovery pressure can be adjusted according to the target cooling temperature section, which has the advantage of increasing the degree of freedom in process design. In other words, by efficiently configuring the main cooling process, a high hydrogen liquefaction efficiency can be obtained.

[0070] The main refrigeration cycle (200) may further include a main refrigeration expansion valve (214) and a main refrigeration compressor (215). The main refrigeration expansion valve (214) may be positioned downstream of a second main refrigeration branch point (212) in the main refrigeration line (210). The main refrigerant separated at the second main refrigeration branch point (212) may be introduced into the main refrigeration expansion valve (214) and expanded to a low pressure (LP). To increase expansion efficiency, the main refrigeration expansion valve (214) may further include an expander for isentropically expanding hydrogen in the refrigeration line, and may be formed as a combination of the expansion valve and the expander. The expander may lower the temperature of the hydrogen and, incidentally, generate power from the expansion of the hydrogen.

[0071] The main main-cooling compressor (215) may be placed downstream of the main-cooling expansion valve (214) in the main main-cooling line (210). The main main-cooling compressor (215) may be arranged to compress the main-cooling refrigerant of the main main-cooling line (210) that has been cooled through the heat exchange unit (30).

[0072] The main cooling cycle (200) may further include a first main cooling expander (221) and a first main cooling compressor (222). The first main cooling expander (221) may be disposed in the first main cooling line (220). The first main cooling expander (221) may be configured to expand high pressure main cooling refrigerant (HP) separated at the first main cooling branch point (211) to a primary intermediate pressure (MP1). For example, the first main cooling compressor (222) may be disposed in the first main cooling line (220) and downstream of the first main cooling expander (221). The first main cooling compressor (222) may be arranged to compress the main cooling refrigerant of the first main cooling line (220) that has been cooled through the heat exchange unit (30). However, as another example, the first main cooling compressor (222') may be placed in the main main cooling line (210).

[0073] The main cooling cycle (200) may further include a second main cooling expander (231) and a second main cooling compressor (232). The second main cooling expander (231) may be disposed in the second main cooling line (230). The second main cooling expander (231) may be configured to expand high pressure main cooling refrigerant (HP) separated at the second main cooling branch point (212) to a secondary intermediate pressure (MP2). The second main cooling compressor (232) may be disposed in the second main cooling line (230) and may be disposed downstream of the second main cooling expander (231). The second main cooling compressor (232) may be arranged to compress the main cooling refrigerant of the second main cooling line (230) that has been cooled through the heat exchange unit (30). However, as another example, the second main cooling compressor (232') may be placed in the main main cooling line (210).

[0074] The compression ratio of the main main-cooling compressor (215) may be greater than or equal to the compression ratios of the first main-cooling compressor (222) and the second main-cooling compressor (232). The compression ratio of the second main-cooling compressor (232) may be greater than or equal to the compression ratio of the first main-cooling compressor (222).

[0075] Heat exchanger (30)

[0076] The heat exchange unit (30) may include a first heat exchanger (31) and a second heat exchanger (32). The first heat exchanger (31) and the second heat exchanger (32) may be arranged to exchange heat between the pre-cooling cycle (100) and the main cooling cycle (200) and the cooling line unit (20). The second heat exchanger (32) may be arranged to pass downstream of the point where the first heat exchanger (31) passes through the cooling line unit (20). The hydrogen in the cooling line unit (20) that has passed through the second heat exchanger (32) may be at a lower temperature than the hydrogen in the cooling line unit (20) that has passed through the first heat exchanger (31).

[0077] The first heat exchanger (31) may be arranged so that the first pre-cooling line (120) and the second pre-cooling line (130) pass through it. In addition, the first heat exchanger (31) may be arranged so that the main main cooling line (210), the first main cooling line (220), and the second main cooling line (230) pass through it.

[0078] The second heat exchanger (32) may be arranged so that the first pre-cooling line (120) passes through it. This may mean that, unlike the first heat exchanger (31), the second heat exchanger (32) does not pass through the second pre-cooling line (130).

[0079] Additionally, the second heat exchanger (32) can be arranged so that the main main cooling line (210), the first main cooling line (220), and the second main cooling line (230) pass through it.

[0080] For example, a cryogenic adsorber may be placed in the second heat exchanger (32).

[0081] The heat exchange unit (30) may further include a third heat exchanger (33), a fourth heat exchanger (34), a fifth heat exchanger (35), and a sixth heat exchanger (36). The third heat exchanger (33), the fourth heat exchanger (34), the fifth heat exchanger (35), and the sixth heat exchanger (36) may be provided to exchange heat between the main cooling cycle (200) and the cooling line unit (20).

[0082] The fourth heat exchanger (34) may be arranged downstream of the point where the third heat exchanger (33) passes through the cooling line section (20). The fifth heat exchanger (35) may be arranged downstream of the point where the fourth heat exchanger (34) passes through the cooling line section (20). The sixth heat exchanger (36) may be arranged downstream of the point where the fifth heat exchanger (35) passes through the cooling line section (20).

[0083] The hydrogen in the cooling line section (20) that has passed through the third heat exchanger (33) may be at a lower temperature than the hydrogen in the cooling line section (20) that has passed through the second heat exchanger (32). The hydrogen in the cooling line section (20) that has passed through the fourth heat exchanger (34) may be at a lower temperature than the hydrogen in the cooling line section (20) that has passed through the third heat exchanger (33). The hydrogen in the cooling line section (20) that has passed through the fifth heat exchanger (35) may be at a lower temperature than the hydrogen in the cooling line section (20) that has passed through the fourth heat exchanger (34). The hydrogen in the cooling line section (20) that has passed through the sixth heat exchanger (36) may be at a lower temperature than the hydrogen in the cooling line section (20) that has passed through the fifth heat exchanger (35).

[0084] The third heat exchanger (33) and the fourth heat exchanger (34) may be arranged so that the portion located between the first main cooling branch point (211) and the second main cooling branch point (212) of the main cooling line (210) passes therethrough. The third heat exchanger (33) may be arranged so that the main main cooling line (210), the first main cooling line (220), and the second main cooling line (230) pass therethrough. The fourth heat exchanger (34) may be arranged so that the main main cooling line (210) and the second main cooling line (230) pass therethrough. This may mean that, unlike the third heat exchanger (33), the fourth heat exchanger (34) does not pass therethrough the first main cooling line (220).

[0085] The fifth heat exchanger (35) and the sixth heat exchanger (36) may be arranged so that the portion located between the second main cooling branch point (212) and the main cooling expansion valve (214) of the main main cooling line (210) passes through the fifth heat exchanger (35). The main main cooling line (210) and the second main cooling line (230) may pass through the fifth heat exchanger (35). The sixth heat exchanger (36) may be arranged so that the main main cooling line (210) passes through it. This may mean that, unlike the fifth heat exchanger (35), the second main cooling line (230) does not pass through the sixth heat exchanger (36).

[0086] Specifically, the main refrigerant circulated through the main main refrigerant line (210) sequentially passes through the fifth heat exchanger (35), the fourth heat exchanger (34), the third heat exchanger (33), the second heat exchanger (32), and the first heat exchanger (31) from the sixth heat exchanger (36), and can cool the hydrogen in the cooling line section (20). In this process, the temperature of the hydrogen in the cooling line section (20) that passes through each heat exchanger can decrease as it goes from the first heat exchanger (31) to the sixth heat exchanger (36).

[0087] A conversion module (30') may be placed in the second heat exchanger (32), the third heat exchanger (33), the fourth heat exchanger (34), the fifth heat exchanger (35), and the sixth heat exchanger (36).

[0088] For example, the main cold refrigerant flowing into the 6th heat exchanger (36) may have a temperature of 20K.

[0089] Other examples

[0090] Figures 5 to 7 are drawings illustrating a high-efficiency liquefaction system according to another embodiment.

[0091] As another example, as illustrated in FIG. 5, the first main cooling junction point may be a point of the main main cooling line (210), and the second main cooling junction point may be a point of the first main cooling line (220). In this case, the second main cooling junction point may be located downstream of the first main cooling compressor (222).

[0092] As another example, as illustrated in FIG. 6, the first main refrigeration confluence point may be a point of the main main refrigeration line (210), and the second main refrigeration confluence point may be a point of the first main refrigeration line (220). At this time, the second main refrigeration confluence point may be located upstream of the first main refrigeration compressor (222). At this time, the main refrigerant that has passed through the second main refrigeration compressor (232) may be introduced back into the first main refrigeration compressor (222). At this time, the compression ratio of the second main refrigeration compressor (232) may be the same as that of the first main refrigeration compressor (222).

[0093] As another example, as illustrated in FIG. 7, the first main cold confluence point may be a point of the main cold line (210), and the second main cold confluence point may be another point of the main cold line (210). In this case, the second main cold confluence point may be located upstream of the first main cold confluence point.

[0094] At this time, the first main-cooling compressor (222') and the second main-cooling compressor (232') may be arranged in the main main-cooling line (210). The first main-cooling compressor (222') may be arranged downstream of the main main-cooling compressor (215). The second main-cooling compressor (232') may be arranged downstream of the main main-cooling compressor (215) and upstream of the first main-cooling compressor (222').

[0095] The main refrigerant that has passed through the second main refrigerant compressor (232') can be fed back into the first main refrigerant compressor (222'). In addition, the main refrigerant that has passed through the main main refrigerant compressor (215) can be fed back into the first main refrigerant compressor (222') through the second main refrigerant compressor (232').

[0096] At this time, the compression ratio of the main main refrigeration compressor (215) may be the same as the compression ratios of the first main refrigeration compressor (222') and the second main refrigeration compressor (232').

[0097] The above description is merely an illustrative illustration of the technical idea of ​​the present invention, and those skilled in the art will appreciate that various modifications and variations can be made without departing from the essential characteristics of the present invention. Therefore, the embodiments disclosed in the present invention are intended to illustrate, rather than limit, the technical idea of ​​the present invention, and the scope of the technical idea of ​​the present invention is not limited by these embodiments. The scope of protection of the present invention should be interpreted by the following claims, and all technical ideas within a scope equivalent thereto should be interpreted as being included in the scope of the rights of the present invention.

[0098]

[0099] [Explanation of symbols]

[0100] 10: Cooling cycle section

[0101] 20: Cooling line section

[0102] 21: Cooling line

[0103] 22: Cooling expansion valve

[0104] 23: Cooling gas-liquid separator

[0105] 30: Heat exchanger

[0106] 30': Conversion module

[0107] 31: First heat exchanger

[0108] 32: Second heat exchanger

[0109] 33: Third heat exchanger

[0110] 34: 4th heat exchanger

[0111] 35: Fifth heat exchanger

[0112] 36: 6th heat exchanger

[0113] 100: Pre-cooling cycle

[0114] 110: First gas-liquid separator

[0115] 120: 1st pre-cooling line

[0116] 121: First pre-cooling expansion valve

[0117] 122: First pre-cooling compressor

[0118] 130: 2nd pre-cooling line

[0119] 131: Second pre-cooling expansion valve

[0120] 132: Second pre-cooling compressor

[0121] 140: Connection pre-cooling line

[0122] 141: Pre-cooling mixer

[0123] 150: Second gas-liquid separator

[0124] 160: Third pre-cooling line

[0125] 161: Third pre-cooling compressor

[0126] 162: Aftercooler

[0127] 170: 4th pre-cooling line

[0128] 171: Precooling pump

[0129] 200: Main cooling cycle

[0130] 210: Main Bon-Neng Line

[0131] 211: First Bon-Neng Branch

[0132] 212: Second Bon-Neng Branch

[0133] 213: Main cold mixer

[0134] 214: Main cooling expansion valve

[0135] 215: Main refrigerated compressor

[0136] 220: First main cooling line

[0137] 221: First main cold expander

[0138] 222, 222': 1st main refrigeration compressor

[0139] 230: Second main cooling line

[0140] 231: Second main cold expansion device

[0141] 232, 232': Second main refrigerant compressor

Claims

1. A cooling cycle section including a pre-cooling cycle configured to circulate a pre-cooling refrigerant and a main cooling cycle configured to circulate a main cooling refrigerant; A cooling line section through which a cooling target object to be cooled by the cooling cycle section passes; and It includes a heat exchanger that exchanges heat between the cooling cycle section and the cooling line section, The above main cooling cycle is, Main Bon-Neng Line; A first main cooling line branching from the first main cooling branch point of the main main cooling line and joining at the first main cooling junction point, which is a point of the main main cooling line; and Includes a second main cooling line branching from the second main cooling branch point of the main main cooling line and joining to the second main cooling junction point, which is a point of the main main cooling line or the first main cooling line, A high-efficiency hydrogen liquefaction system, wherein the second main refrigeration branch point is located downstream compared to the first main refrigeration branch point.

2. In claim 1, The above main cooling cycle is, A main cooling expansion valve disposed downstream of the second main cooling branch point in the main main cooling line; and A high-efficiency hydrogen liquefaction system further comprising a main main-cooled compressor disposed downstream of the above-mentioned main-cooled expansion valve.

3. In claim 2, The above main cooling cycle is, A first main cooling expander arranged in the first main cooling line; and A high-efficiency hydrogen liquefaction system further comprising a second main-cooling expander arranged in the second main-cooling line.

4. In claim 3, The above main cooling cycle is, A first main-cooling compressor disposed in the first main-cooling line and disposed downstream of the first main-cooling expander; and A high-efficiency hydrogen liquefaction system further comprising a second main-cooling compressor disposed in the second main-cooling line and disposed downstream of the second main-cooling expander.

5. In claim 4, The above main cooling cycle is, A first main cooling compressor disposed on the main cooling line but disposed downstream of the main main cooling compressor; and A high-efficiency hydrogen liquefaction system further comprising a second main-cooling compressor disposed on the main main-cooling line, downstream of the main main-cooling compressor, and upstream of the first main-cooling compressor.

6. In claim 3, The above pre-cooling cycle is, A first gas-liquid separator provided to separate the incoming pre-cooled refrigerant into gas and liquid; A first pre-cooling line through which the pre-cooled refrigerant in the gas phase discharged from the first gas-liquid separator passes; A second pre-cooling line through which the liquid pre-cooling refrigerant discharged from the first gas-liquid separator passes; A first pre-cooling line and a connecting pre-cooling line connected to the second pre-cooling line; A second gas-liquid separator provided to separate the refrigerant flowing in from the above-mentioned connecting pre-cooling line into gas and liquid; A third pre-cooling line through which the pre-cooled refrigerant in the gas phase discharged from the second gas-liquid separator passes and is connected to the first gas-liquid separator; and A high-efficiency hydrogen liquefaction system, comprising a fourth pre-cooling line through which liquid pre-cooling refrigerant discharged from the second gas-liquid separator passes and which is connected to the first gas-liquid separator.

7. In claim 6, The above pre-cooling cycle is, A first pre-cooling expansion valve arranged in the first pre-cooling line; A first pre-cooling compressor disposed in the first pre-cooling line and disposed downstream of the first pre-cooling expansion valve; A second pre-cooling expansion valve arranged in the second pre-cooling line; and A high-efficiency hydrogen liquefaction system further comprising a second pre-cooling compressor disposed in the second pre-cooling line and disposed downstream of the second pre-cooling expansion valve.

8. In claim 6, The above pre-cooling cycle is, a third pre-cooling compressor arranged in the third pre-cooling line; and A high-efficiency hydrogen liquefaction system further comprising a pre-cooling pump arranged in the fourth pre-cooling line to pump the pre-cooled refrigerant in the fourth pre-cooling line toward the first gas-liquid separator.

9. In claim 8, The above heat exchanger, A first heat exchanger configured to exchange heat between the pre-cooling cycle and the main cooling cycle and the cooling line section; and A high-efficiency hydrogen liquefaction system, which is provided to exchange heat between the pre-cooling cycle and the main cooling cycle and the cooling line section, and includes a second heat exchanger passing downstream of the point where the first heat exchanger passes among the cooling line sections.

10. In claim 9, The first heat exchanger is arranged so that the first pre-cooling line and the second pre-cooling line pass through it, The above second heat exchanger is a high-efficiency hydrogen liquefaction system, wherein the first pre-cooling line is arranged to pass through the above second heat exchanger.

11. In claim 2, The above heat exchanger, A third heat exchanger configured to exchange heat between the main cooling cycle and the cooling line section; A fourth heat exchanger is provided to exchange heat between the main cooling cycle and the cooling line section, and is located downstream of the point where the third heat exchanger passes among the cooling line sections; A fifth heat exchanger is provided to exchange heat between the main cooling cycle and the cooling line section, and is located downstream of the point where the fourth heat exchanger passes among the cooling line sections; and A high-efficiency hydrogen liquefaction system, which is provided to exchange heat between the main cooling cycle and the cooling line section, and includes a sixth heat exchanger passing downstream of the point where the fifth heat exchanger passes among the cooling line sections.

12. In claim 11, The third heat exchanger and the fourth heat exchanger are, A high-efficiency hydrogen liquefaction system, wherein a portion of the main main refrigeration line is positioned so as to pass between the first main refrigeration branch point and the second main refrigeration branch point.

13. In claim 12, The third heat exchanger is, The main cooling line, the first cooling line, and the second cooling line are arranged to pass through, The above fourth heat exchanger is, A high-efficiency hydrogen liquefaction system, in which the main main cooling line and the second main cooling line are arranged to pass through.

14. In claim 11, The fifth heat exchanger and the sixth heat exchanger are, A high-efficiency hydrogen liquefaction system, wherein a portion of the main main refrigeration line is positioned so as to pass between the second main refrigeration branch point and the main refrigeration expansion valve.

15. In claim 14, The above fifth heat exchanger is, The above main cooling line and the above second main cooling line are arranged to pass through, The above sixth heat exchanger is, A high-efficiency hydrogen liquefaction system arranged so that the above main cooling line passes through.

16. In claim 4, A high-efficiency hydrogen liquefaction system, wherein the compression ratio of the main main refrigerated compressor is greater than or equal to the compression ratios of the first main refrigerated compressor and the second main refrigerated compressor.

17. In claim 7, A high-efficiency hydrogen liquefaction system, wherein the compression ratio of the first pre-cooling compressor is greater than the compression ratio of the second pre-cooling compressor.

18. In claim 1, The above main refrigerant is a high-efficiency hydrogen liquefaction system containing helium.

19. Pre-cooling step for cooling the object to be cooled in the atmosphere; and It includes a main cooling step of liquefying the cooling target object of the above-mentioned pre-cooled gas, The above pre-cooling step is performed by a pre-cooling cycle, The above cooling step is performed by a cooling cycle, The above main cooling cycle is, Main Bon-Neng Line; A first main cooling line branching from the first main cooling branch point of the main main cooling line and joining at the first main cooling junction point, which is a point of the main main cooling line; and Includes a second main cooling line branching from the second main cooling branch point of the main main cooling line and joining at the second main cooling junction point, which is a point of the main main cooling line or the first main cooling line; A hydrogen liquefaction process wherein the second main cooling branch point is located downstream compared to the first main cooling branch point.

20. In claim 19, The above pre-cooling cycle is, A first gas-liquid separator provided to separate the incoming pre-cooled refrigerant into gas and liquid; A first pre-cooling line through which the pre-cooled refrigerant in the gas phase discharged from the first gas-liquid separator passes; A second pre-cooling line through which the liquid pre-cooling refrigerant discharged from the first gas-liquid separator passes; A first pre-cooling line and a connecting pre-cooling line connected to the second pre-cooling line; A second gas-liquid separator provided to separate the refrigerant flowing in from the above-mentioned connecting pre-cooling line into gas and liquid; A third pre-cooling line through which the pre-cooled refrigerant in the gas phase discharged from the second gas-liquid separator passes and is connected to the first gas-liquid separator; and A hydrogen liquefaction process, comprising a fourth pre-cooling line through which a liquid pre-cooling refrigerant discharged from the second gas-liquid separator passes and which is connected to the first gas-liquid separator.

Images