System for separating gas in cryogenic environment

Abstract

The present invention relates to a system for separating gas in a cryogenic environment. According to an embodiment of the present disclosure, the system for separating gas in the cryogenic environment may include: a system for separating gas in the cryogenic environment comprising: a heat exchange unit cooling methane pyrolysis gas from which carbon black is removed, a steam methane reforming gas, and an ammonia decomposition gas to produce a cooling gas including liquefied hydrocarbon, liquefied carbon dioxide, and liquefied ammonia; a recovery unit connected to the heat exchange unit to receive the cooling gas from the heat exchange unit, and condensing the liquefied hydrocarbon, the liquefied carbon dioxide, and the liquefied ammonia included in the cooling gas to recover the liquefied hydrocarbon, the liquefied carbon dioxide, and the liquefied ammonia included in the cooling gas; a separation unit connected to the recovery unit, receiving a remaining gas from which the liquefied hydrocarbon, the liquefied carbon dioxide, and the liquefied ammonia is removed from the cooling gas, and separating a methane gas, a carbon monoxide gas, a nitrogen gas, and a hydrogen gas included in the remaining gas in the cryogenic environment; and a cold heat supply unit connecting the separation unit and the heat exchange unit, and providing at least one of cold heat of the methane gas, the carbon monoxide gas, the nitrogen gas, and the hydrogen gas separated by the separation unit in the cryogenic environment to the heat exchange unit.

Description

[Technical Field]

[0001] The present invention relates to a system for separating gas in a cryogenic environment.[Background Art]

[0002] As global warming is accelerated, problems such as abnormal climate and rising sea levels are occurring worldwide. The main cause of this worsening global warming is the increase in greenhouse gas emissions, and carbon dioxide emissions account for the largest proportion of the greenhouse gas emissions, so that a need to reduce carbon dioxide emissions is gradually increasing.

[0003] Accordingly, countries around the world including South Korea have declared carbon neutrality with a goal of net-zero carbon emissions in a process of establishing a climate change response strategy and are establishing an implementation system to realize the same.

[0004] In order to realize the carbon neutrality, a method of utilizing carbon-free energy sources such as hydrogen and ammonia is being suggested. As hydrogen does not emit carbon dioxide or other harmful substances when burned or generating electricity, research on producing and transporting hydrogen has been conducted in various methods.

[0005] Hydrogen may be produced by various methods, but in particular, various methods for producing hydrogen from natural gas is being reviewed. Among the various methods for producing hydrogen from natural gas, methane pyrolysis technique is a technique that pyrolyzes methane in a high-temperature environment and directly decomposes the same into carbon black and hydrogen. However, unreacted methane remains during this process, and hydrocarbon (C x H y ) is generated as a byproduct, thereby requiring separation. As another method for producing hydrogen from natural gas, steam methane reforming method is a method of producing hydrogen by adding steam to natural gas and carbon dioxide gas is generated, and carbon monoxide gas is generated as a byproduct, thereby requiring separation.

[0006] In addition, a method of utilizing ammonia as a means of transporting hydrogen is being considered a lot. Ammonia is a mixture of nitrogen and hydrogen that may be produced through synthesis, and when nitrogen and hydrogen are separated again, high-purity hydrogen may be utilized, so that it has attracted attention as a technique for storing and transporting hydrogen. However, when extracting hydrogen again from ammonia, it is necessary to separate unreacted ammonia and nitrogen.

[0007] Various techniques are being utilized to separate and purify hydrogen, but since the process is complex and the system should be large in scale, it is less economical, and since remaining gases except hydrogen are separated at once during purification, there is a problem that it is difficult to utilize the separated gas, thereby reducing system efficiency.

[0008] Accordingly, there is a need for a development of technique that may secure economic feasibility by simplifying the separation process compared to the conventional method, secure the system efficiency by separating and recirculating for each component, and improve the separation efficiency.[Disclosure][Technical Problem]

[0009] The embodiments of the present invention have been devised to solve the above-described conventional problems and is directed to providing of a system for separating gas in a cryogenic environment capable of securing economic feasibility by simplifying the separation process compared to conventional methods, securing the system efficiency by separating and recirculating for each component, and improving the separation efficiency.[Technical Solution]

[0010] According to an aspect of the present invention, it is possible to provide a system for separating gas in a cryogenic environment including: a heat exchange unit cooling methane pyrolysis gas from which carbon black is removed, a steam methane reforming gas, and an ammonia decomposition gas to produce a cooling gas including liquefied hydrocarbon, liquefied carbon dioxide, and liquefied ammonia; a recovery unit connected to the heat exchange unit to receive the cooling gas from the heat exchange unit, and condensing the liquefied hydrocarbon, the liquefied carbon dioxide, and the liquefied ammonia included in the cooling gas to recover the liquefied hydrocarbon, the liquefied carbon dioxide, and the liquefied ammonia included in the cooling gas; a separation unit connected to the recovery unit, receiving a remaining gas from which the liquefied hydrocarbon, the liquefied carbon dioxide, and the liquefied ammonia is removed from the cooling gas, and separating a methane gas, a carbon monoxide gas, a nitrogen gas, and a hydrogen gas included in the remaining gas in the cryogenic environment; and a cold heat supply unit connecting the separation unit and the heat exchange unit, and providing at least one of cold heat of the methane gas, the carbon monoxide gas, the nitrogen gas, and the hydrogen gas separated by the separation unit in the cryogenic environment to the heat exchange unit.

[0011] In addition, the separation unit may include a cryogenic separation device that receives the remaining gas and separates the remaining gas into the methane gas, the carbon monoxide gas, the nitrogen gas, and the hydrogen gas by diffusing the remaining gas through a separation membrane in the cryogenic environment, wherein the separation membrane may include a cryogenic separating membrane that increases a purity of the separated gas by increasing a selectivity of the remaining gas and reducing a diffusion speed of the remaining gas in the cryogenic environment rather than in a non-cryogenic environment.

[0012] In addition, the cold heat supply unit may include a cold heat supply line of methane, carbon monoxide, and nitrogen that connects the cryogenic separation device and the heat exchange unit, and a cold heat production device of the methane, carbon monoxide, and nitrogen that is equipped on a cold heat line of the methane, carbon monoxide, and nitrogen, receives the methane, the carbon monoxide, and the nitrogen gas separated by the cryogenic separation device in the cryogenic environment to cool the same, and supplies the same to the heat exchange unit.

[0013] In addition, cold heat of the methane, the carbon monoxide, and the nitrogen gas produced in the cold heat production device of the methane, carbon monoxide, and nitrogen may be transferred to the methane pyrolysis gas from which carbon black is removed, the steam methane reforming gas, and the ammonia decomposition gas that are supplied to the heat exchange unit.

[0014] In addition, cold heat of the hydrogen gas separated by the cryogenic separation device in the cryogenic environment may be transferred to the methane pyrolysis gas from which carbon black is removed, the steam methane reforming gas, and the ammonia decomposition gas that are supplied to the heat exchange unit, and a storage unit that receives and stores the hydrogen gas after transferring the cold heat to the ammonia decomposition gas may be further included.

[0015] In addition, the separation unit may include a plurality of cryogenic adsorption devices that receive the remaining gas and separate the remaining gas into the nitrogen gas and the hydrogen gas using an adsorbent, and the adsorbent may include a cryogenic adsorbent that increases the purity of separated gas by increasing an adsorption amount of the remaining gas by improving an adsorption performance in the cryogenic environment rather than in the non-cryogenic environment.

[0016] In addition, the cold heat supply unit may include a hydrogen cold heat supply line that connects the cryogenic adsorption device and the heat exchange unit, and a hydrogen cold heat production device that is equipped on the hydrogen cold heat supply line and receives the hydrogen gas separated by the cryogenic adsorption device in the cryogenic environment to cool the same, and supplies the same to the heat exchange unit.

[0017] In addition, cold heat of the hydrogen gas produced in the hydrogen cold heat production device may be transferred to the methane pyrolysis gas from which carbon black is removed, the steam methane reforming gas, and the ammonia decomposition gas supplied to the heat exchange unit, and a storage unit that receives and stores the hydrogen gas after transferring the cold heat to the methane pyrolysis gas from which carbon black is removed, the steam methane reforming gas, and the ammonia decomposition gas may be further included.

[0018] In addition, at least a part of the hydrogen gas after transferring the cold heat to the methane pyrolysis gas from which carbon black is removed, the steam methane reforming gas, and the ammonia decomposition gas stored in the storage unit may be selectively supplied to a plurality of the cryogenic adsorption devices to utilize for regenerating the adsorbent.

[0019] In addition, a degassing unit that receives the adsorbed gas adsorbed in the plurality of cryogenic adsorption devices to degas the same may be further included.

[0020] In addition, the adsorbed gas degassed in the degassing unit may supplied to the heat exchange unit, and cold heat of the adsorbed gas supplied to the heat exchange unit may be transferred to the methane pyrolysis gas from which carbon black is removed, the steam methane reforming gas, and the ammonia decomposition gas that are supplied to the heat exchange unit.[Advantageous Effects]

[0021] According to the embodiments of the present invention, a load of the separation unit can be reduced to increase a separation ability by recovering a specific gas by phase-changing, and system efficiency and economic feasibility can also be improved by selling the gas for a separate purpose or recirculating the gas into the system for utilization.

[0022] In addition, the separation process can be simplified by maximizing the performance of the adsorbent through a cryogenic adsorption process in the cryogenic environment, thereby ensuring economic feasibility.

[0023] In addition, a separation efficiency of methane gas, carbon monoxide gas, nitrogen gas, and hydrogen gas can be improved by reducing a diffusion speed of the remaining gas consisting of the methane gas, the carbon monoxide, the nitrogen gas, and the hydrogen gas through the cryogenic separation process in a cryogenic environment and increasing the selectivity.

[0024] In addition, cold heat through kinetic energy of the methane gas, the carbon monoxide gas, the nitrogen gas, and the hydrogen gas separated from the remaining gas is produced, and the produced cold heat is utilized for liquefaction of the hydrocarbon gas, the carbon dioxide gas, and the ammonia gas, thereby having high energy efficiency.[Description of Drawings]

[0025] FIG. 1 is a block diagram showing a system for separating gas in a cryogenic environment according to an embodiment of the present invention. FIG. 2 is a schematic diagram of the system for separating gas in the cryogenic environment of FIG. 1. FIG. 3 is a block diagram showing a system for separating gas in a cryogenic environment according to another embodiment of the present invention. FIG. 4 is a schematic diagram of the system for separating gas in the cryogenic environment of FIG. 3. [Modes of the Invention]

[0026] Hereinafter, specific embodiments for implementing the idea of the present invention will be described in detail with reference to the drawings.

[0027] In addition, when describing the present invention, when it is determined that a detailed description of a related known configuration or function may obscure the gist of the present invention, the detailed description thereof will be omitted.

[0028] Additionally, it will be understood that when a component is referred to as being 'connected' to another component, it may be directly connected to another component or other components may be present therebetween.

[0029] The terms used herein are only to describe specific embodiments and are not intended to limit the present invention. Singular expressions include plural expressions unless the context clearly indicates otherwise.

[0030] In addition, it is to be noted in advance that the expressions such as one side, the other side, upper side, lower side, etc. in this specification are described based on the diagram shown in the drawing, and may be expressed differently if the direction of the object is changed. For the same reason, some components in the attached drawings are exaggerated, omitted, or schematically illustrated, and the size of each component does not fully match the actual size thereof.

[0031] Additionally, terms that include ordinal numbers, such as first, second, etc., may be used to describe various components, but the components are not limited by such terms. These terms are only used for the purpose of distinguishing one component from the other.

[0032] The term "include" used herein is used to specify specific characteristics, regions, integers, steps, operations, components and / or compositions, and does not exclude any of presence or addition of other specific characteristics, regions, integers, steps, operations, components, composition and / or groups.

[0033] Hereinafter, a specific configuration of a system for separating gas in a cryogenic environment according to an embodiment of the present invention will be described with reference to the drawings.

[0034] Referring to FIGS. 1 and 2, a system 1 for separating gas in the cryogenic environment according to an embodiment of the present invention may include a heat exchange unit 10, a recovery unit 20, a separation unit 30, a cold heat supply unit 40, a storage unit 50, and a degassing unit 60.

[0035] The heat exchange unit 10 may cool a methane pyrolysis gas from which carbon black is removed, a steam methane reforming gas, and an ammonia decomposition gas to generate a cooling gas including liquefied hydrocarbon, liquefied carbon dioxide, and liquefied ammonia.

[0036] To this end, the heat exchange unit 10 may transfer a cold heat of a hydrogen gas discharged from a hydrogen cold heat production device 42 of the cold heat supply unit 40 to the methane pyrolysis gas from which carbon black is removed, the steam methane reforming gas, and the ammonia decomposition gas to cool the methane pyrolysis gas from which carbon black is removed, the steam methane reforming gas, and the ammonia decomposition gas. In other words, hydrocarbon in gaseous state, carbon dioxide, and ammonia included in the methane pyrolysis gas from which carbon black is removed, the steam methane reforming gas, and the ammonia decomposition gas may be cooled through the heat exchange unit 10 and to phase-change into a liquid or solid state.

[0037] Such a heat exchange unit 10 may be equipped as a first-stage heat exchanger as an example and may cool the methane pyrolysis gas from which carbon black is removed, the steam methane reforming gas, and the ammonia decomposition gas to about -140 °C to about - 100 °C. In the present embodiment, a case in which the heat exchange unit 10 is equipped as the first-stage heat exchanger is described as an example, but depending on a presence or absence of moisture in the methane pyrolysis gas from which carbon black is removed, the steam methane reforming gas, and the ammonia decomposition gas, the heat exchange unit 10 may also be equipped as a second-stage heat exchanger. When the heat exchange unit 10 is equipped as the second-stage heat exchanger, the rear temperature of the first-stage heat exchanger may be set to about 0°C, and a rear end temperature of the second-stage heat exchanger may be set to about - 100 °C. When heat exchange unit 10 is equipped as the second-stage heat exchanger in this way, the recovery unit 20 may be equipped at a rear end of the first-stage heat exchanger.

[0038] The recovery unit 20 is connected to the heat exchange unit 10 and receives the cooling gas from the heat exchange unit 10, and condenses the liquefied hydrocarbon, the liquefied carbon dioxide, and the liquefied ammonia included in the cooling gas to recover the liquefied hydrocarbon, the liquefied carbon dioxide, and the liquefied ammonia included in the cooling gas.

[0039] In this case, when the heat exchange unit 10 is equipped as the first-stage heat exchanger, the recovery unit 20 may separate the liquefied hydrocarbon, the liquefied carbon dioxide, and the liquefied ammonia from the cooling gas, and when the heat exchange unit 10 is equipped as the second-stage heat exchanger, the recovery unit 20 may separate the moisture from the liquefied hydrocarbon, the liquefied carbon dioxide, and the liquefied ammonia from the cooling gas separately.

[0040] The recovery unit 20 may be equipped as an ammonia condensation tank including a structure that promotes condensation of the liquefied hydrocarbon, the liquefied carbon dioxide, and the liquefied ammonia, or a demister that removes moisture included in the cooling gas, etc. as an example.

[0041] Meanwhile, the liquefied hydrocarbon, the liquefied carbon dioxide, and the liquefied ammonia condensed through the recovery unit 20 and separated from the cooling gas, are not in a state mixed with methane gas, carbon monoxide gas, nitrogen gas, and hydrogen gas, and thus may be understood as high-purity liquefied hydrocarbon, liquefied carbon dioxide, and liquefied ammonia. Such high-purity liquefied hydrocarbon, liquefied carbon dioxide, and liquefied ammonia may be transferred to an ammonia storage tank (not shown) through a separate ammonia pump (not shown).

[0042] Although not shown, the high-purity hydrocarbon and carbon dioxide transported to a liquefied hydrocarbon storage tank and a liquefied carbon dioxide storage tank may be used for a different purpose. The high-purity ammonia transported to the ammonia storage tank may be recirculated to an ammonia decomposition process. Conventionally, there is a problem that ammonia separated from the ammonia decomposition gas is mixed with the nitrogen gas and the hydrogen gas, which causes the ammonia decomposition process to be complex when the ammonia separated from the ammonia decomposition gas is recirculated to an ammonia decomposition reaction. On the other hand, in a case of the present embodiment, only the high-purity ammonia is recirculated to the ammonia decomposition process, and thus the ammonia decomposition process may be simplified.

[0043] The separation unit 30 may be connected to the recovery unit 20, and receive the remaining gas from which the liquefied hydrocarbon, the liquefied carbon dioxide, and the liquefied ammonia is removed from the cooling gas, and separate the methane gas, the carbon monoxide gas, the nitrogen gas, and the hydrogen gas included in the remaining gas in a cryogenic environment.

[0044] To this end, the separation unit 30 may include a plurality of cryogenic adsorption devices 31 that separate the remaining gas into the nitrogen gas and the hydrogen gas using an adsorbent.

[0045] In this case, the adsorbent provided to the cryogenic adsorption device 31 may include a cryogenic adsorbent that has an increased adsorption performance in the cryogenic environment than in a non-cryogenic environment. Here, the non-cryogenic environment may refer to an environment other than the cryogenic environment, for example, a room temperature / high pressure environment.

[0046] The cryogenic adsorption device 31 may be miniaturized by maximizing the adsorption performance of the cryogenic adsorbent in the cryogenic environment compared to the related art. For example, the cryogenic adsorbent may be composed of a material capable of adsorbing a specific gas such as a carbon molecular sieve, zeolite, or activated carbon. The cryogenic adsorbent may be composed of not only a solid-state adsorbent but also a liquid state such as DEPG, NMP, PZ, MDEA, and DIPA.

[0047] Meanwhile, at least a part of the plurality of cryogenic adsorption devices 31 may be operated to produce hydrogen, and a remainder of the plurality of cryogenic adsorption devices 31 may be operated to regenerate the adsorbent. When the cryogenic adsorption device 31 is operated for hydrogen production, the cryogenic adsorption device 31 may receive the remaining gas from the recovery unit 20, and when the cryogenic adsorption device 31 is operated for adsorbent regeneration, the cryogenic adsorption device 31 may receive hydrogen from the storage unit 50. This will be described later.

[0048] In this case, the adsorbed gas adsorbed in the cryogenic adsorption process of the plurality of cryogenic adsorption devices 31 may be supplied to the degassing unit 60 to be degassed. The adsorbed gas degassed through the degassing unit 60 may be composed of the methane gas, the carbon monoxide gas, the nitrogen gas, and the hydrogen gas and may be supplied to the heat exchange unit 10 to be utilized as a cold heat source for cooling the ammonia decomposition gas. This will be described later.

[0049] The plurality of cryogenic adsorption devices 31 may be operated sequentially in the cryogenic environment. In addition, the plurality of cryogenic adsorption devices 31 may be operated variably for hydrogen purity and hydrogen recovery rate according to quality requirements of the produced hydrogen.

[0050] The cold heat supply unit 40 may provide cold heat of the hydrogen gas separated in the cryogenic environment by the separation unit 30 to the heat exchange unit 10.

[0051] To this end, the cold heat supply unit 40 may include the hydrogen cold heat supply line 41 that connects the cryogenic adsorption device 32 and the heat exchange unit 10 and a hydrogen cold heat production device 42 that is equipped on the hydrogen cold heat supply line 41, receives the hydrogen gas separated in the cryogenic environment by the cryogenic adsorption device 31 to cool the same, and supplies the same to the heat exchange unit 10.

[0052] In this case, the hydrogen cold heat production device 42 may be equipped as a means capable of cooling the hydrogen gas, for example, an expander or a freezer. When the hydrogen cold heat production device 42 is equipped as the expander, the hydrogen gas may be cooled without using a separate energy source, and when the hydrogen cold heat production device 42 is equipped as the freezer, the hydrogen gas may be cooled while maintaining a pressure of the hydrogen gas. In addition, the cryogenic adsorption device 31 may be miniaturized compared to a case in which when the hydrogen cold heat production device 44 is equipped as the expander.

[0053] The storage unit 50 may receive and store the hydrogen gas after transferring cold heat to the methane pyrolysis gas from which carbon black is removed, the steam methane reforming gas, and the ammonia decomposition gas. In other words, when the methane pyrolysis gas from which carbon black is removed, the steam methane reforming gas, and the ammonia decomposition gas passing through the heat exchange unit 10 absorb the cold heat of a cryogenic hydrogen gas, a temperature of the cryogenic hydrogen gas may be increased to the room temperature. As such, the hydrogen gas after transferring the cold heat to the methane pyrolysis gas from which carbon black is removed, the steam methane reforming gas, and the ammonia decomposition gas may be understood as a room temperature hydrogen gas.

[0054] In this case, the storage unit 50 may be connected to the heat exchange unit 10, and as an example, may be equipped as a storage tank that stores the room temperature hydrogen gas. The room temperature hydrogen gas stored in the storage unit 50 may be supplied to the cryogenic adsorption device 31 to be utilized for regenerating the adsorbent in the cryogenic adsorption device 31.

[0055] The degassing unit 60 may receive the adsorbed gas adsorbed in the plurality of cryogenic adsorption devices 31 to degas the same. Here, the adsorbed gas may be composed of the methane gas, the carbon monoxide gas, the nitrogen gas, and the hydrogen gas and the degassing unit 60 may be equipped as a vacuum pump as an example.

[0056] The adsorbed gas (hereinafter referred to as "degassed gas") degassed through the degassing unit 60 may be supplied to the heat exchange unit 10. The degassed gas supplied to the heat exchange unit 10 in this way may be utilized to cool the methane pyrolysis gas from which carbon black is removed, the steam methane reforming gas, and the ammonia decomposition gas that are supplied to the heat exchange unit 10.

[0057] The system 1 for separating gas in the cryogenic environment having the above-described configuration may reduce a load of the separation unit to increase a separation ability by recovering a specific gas by phase-changing, and system efficiency and economic feasibility may also be improved by selling the gas for a separate purpose or recirculating the gas into the system for utilization.

[0058] In addition, the separation process can be simplified by maximizing the performance of the adsorbent through a cryogenic adsorption process in the cryogenic environment, thereby ensuring economic feasibility.

[0059] In addition, cold heat through kinetic energy of the hydrogen gas separated from the remaining gas is produced, and the produced cold heat is utilized for liquefaction of the hydrocarbon gas, the carbon dioxide gas, and the ammonia gas, thereby having high energy efficiency.

[0060] Hereinafter, a system for separating gas in a cryogenic environment according to another embodiment of the present invention will be described with reference to FIGS. 3 and 4.

[0061] Referring to FIGS. 3 and 4, a system 1a for separating gas in a cryogenic environment according to another embodiment of the present invention may include a heat exchange unit 10, a recovery unit 20, a separation unit 30a, a cold heat supply unit 40a, and a storage unit 70. However, since the system 1a for separating gas in the cryogenic environment shown in FIGS. 3 and 4 is substantially the same as the system 1 for separating gas in the cryogenic environment described with reference to FIGS. 1 and 2 except for the separation unit 30a, the cold heat supply unit 40a, and the storage unit 70, the following description will focus on the separation unit 30a, the cold heat supply unit 40a, and the storage unit 70 corresponding to differences, and the description and reference numbers of the above-described embodiment will be used for the same parts.

[0062] The separation unit 30a may be connected to the recovery unit 20, and receive remaining gas from which liquefied hydrocarbon, liquefied carbon dioxide, and liquefied ammonia is removed from the cooling gas, and separate the methane gas, the carbon monoxide gas, the nitrogen gas, and the hydrogen gas included in the remaining gas in the cryogenic environment.

[0063] To this end, the separation unit 30a may include a cryogenic separation device 32 that separates the remaining gas into the methane gas, the carbon monoxide gas, the nitrogen gas, and the hydrogen gas by diffusing the remaining gas through a separation membrane in the cryogenic environment.

[0064] In this case, the separation membrane provided in the cryogenic separation device 32 may be a cryogenic separating membrane that reduces a diffusion speed of the remaining gas in the cryogenic environment rather than in a non-cryogenic environment. Here, the non-cryogenic environment may refer to an environment other than the cryogenic environment, for example, a room temperature / high pressure environment.

[0065] Accordingly, a selectivity of the remaining gas passing through the cryogenic separation device 32 is increased, and the diffusion speed is reduced, thereby maximizing the performance of the separation membrane. Furthermore, separation efficiency of the nitrogen gas and the hydrogen gas may also be improved.

[0066] The cold heat supply unit 40a may provide cold heat of the methane gas, the carbon monoxide gas, and the nitrogen gas that are separated by the separation unit 30a in the cryogenic environment to the heat exchange unit 10.

[0067] To this end, the cold heat supply unit 40a may include a cold heat supply line 43 of methane, carbon monoxide, and nitrogen that connects the cryogenic separation device 32 and the heat exchange unit 10, and a cold heat production device 44 of the methane, carbon monoxide, and nitrogen that is equipped on a cold heat line 43 of the methane, carbon monoxide, and nitrogen, receives the methane gas, the carbon monoxide gas, and the nitrogen gas separated by the cryogenic separation device 32 in the cryogenic environment to cool the same, and supplies the same to the heat exchange unit 10.

[0068] In this case, the nitrogen cold heat production device 44 may generate cold heat through kinetic energy of the methane gas, the carbon monoxide gas, and the nitrogen gas discharged from the cryogenic separation device 32. As such, cold heat required for liquefaction of the hydrocarbon gas, the carbon dioxide gas, and the ammonia gas is produced only by the kinetic energy of the methane gas, the carbon monoxide gas, and the nitrogen gas without a separate energy source, thereby having high energy efficiency.

[0069] The nitrogen cold heat production device 44 may be equipped as an expander or a nozzle that produces cold heat by expanding the methane gas, the carbon monoxide gas, and the nitrogen gas discharged from the cryogenic separation device 32.

[0070] In addition, even when the cold heat production device 44 of the methane, carbon monoxide, and nitrogen is equipped as the expander or the nozzle, for example, the remaining gas supplied to the cold heat production device 44 of the methane, carbon monoxide, and nitrogen is composed only of the methane gas, the carbon monoxide gas, the nitrogen gas, and the hydrogen gas from which liquefiable gas has been removed, thereby increasing reliability of the process.

[0071] Meanwhile, in this embodiment, a case in which the cold heat production device 44 of the methane, carbon monoxide, and nitrogen is the expander or the nozzle is described as an example, but this is only an example for convenience of description, and the spirit of the present invention is not to be limited thereto. The cold heat production device 44 of the methane, carbon monoxide, and nitrogen may also be equipped as a freezer module capable of reducing temperature of the methane, the carbon monoxide, and the nitrogen gas discharged from the cryogenic separation device 32.

[0072] The storage unit 70 may receive and store the hydrogen gas after transferring cold heat to the methane pyrolysis gas from which carbon black is removed, the steam methane reforming gas, and the ammonia decomposition gas. In other words, when the methane pyrolysis gas from which carbon black is removed, the steam methane reforming gas, and the ammonia decomposition gas passing through the heat exchange unit 10 absorb the cold heat of a cryogenic hydrogen gas, a temperature of the cryogenic hydrogen gas may be increased to the room temperature. As such, the hydrogen gas after transferring the cold heat to the ammonia decomposition gas may be understood as a room temperature hydrogen gas. The storage unit 70 may be connected to the heat exchange unit 10, and as an example, may be equipped as a storage tank that stores the room temperature hydrogen gas.

[0073] The system 1a for separating gas in the cryogenic environment having the above-described configuration may reduce a load of the separation unit and increase a separation ability by recovering a specific gas by phase-changing, and system efficiency and economic feasibility may also be improved by selling the gas for a separate purpose or recirculating the gas into the system for utilization.

[0074] In addition, a separation efficiency of the methane gas, the carbon monoxide gas, the nitrogen gas, and the hydrogen gas may be improved by reducing the diffusion speed of the remaining gas consisting of the methane gas, the carbon monoxide gas, the nitrogen gas, and the hydrogen gas through the cryogenic separation process in the cryogenic environment and increasing the selectivity.

[0075] In addition, cold heat through kinetic energy of the methane gas, the carbon monoxide gas, and the nitrogen gas separated from the remaining gas is produced, and the produced cold heat is utilized for liquefaction of the hydrocarbon gas, the carbon dioxide gas, and the ammonia gas, thereby having high energy efficiency.

[0076] Although the embodiments of the present invention have been described as specific embodiments, it is merely an example, and the present invention is not limited thereto and it should be interpreted to have the broadest scope in accordance with the basic idea disclosed in this specification. Those skilled in the art may combine / substitute the disclosed embodiments to implement patterns of shapes not specified, but this also does not depart from the scope of the present invention. In addition, those skilled in the art may easily change or modify the disclosed embodiments based on this specification, and it is clear that such changes or modifications also fall within the scope of the present invention.

Claims

1. A system for separating gas in a cryogenic environment, the system comprising: a heat exchange unit cooling methane pyrolysis gas from which carbon black is removed, a steam methane reforming gas, and an ammonia decomposition gas to produce a cooling gas including liquefied hydrocarbon, liquefied carbon dioxide, and liquefied ammonia; a recovery unit connected to the heat exchange unit to receive the cooling gas from the heat exchange unit and condensing the liquefied hydrocarbon, the liquefied carbon dioxide, and the liquefied ammonia included in the cooling gas to recover the liquefied hydrocarbon, the liquefied carbon dioxide, and the liquefied ammonia included in the cooling gas; a separation unit connected to the recovery unit, receiving a remaining gas from which the liquefied hydrocarbon, the liquefied carbon dioxide, and the liquefied ammonia are removed from the cooling gas, and separating methane gas, carbon monoxide gas, nitrogen gas, and hydrogen gas included in the remaining gas in the cryogenic environment; and a cold heat supply unit connecting the separation unit and the heat exchange unit and providing at least one of cold heat of the methane gas, the carbon monoxide gas, the nitrogen gas, and the hydrogen gas separated by the separation unit in the cryogenic environment to the heat exchange unit.

2. The system of claim 1, wherein the separation unit includes a cryogenic separation device that receives the remaining gas and separates the remaining gas into the methane gas, the carbon monoxide gas, the nitrogen gas, and the hydrogen gas by diffusing the remaining gas through a separation membrane in the cryogenic environment, wherein the separation membrane includes a cryogenic separating membrane that increases a purity of the separated gas by increasing selectivity of the remaining gas and reducing a diffusion speed of the remaining gas in the cryogenic environment rather than in a non-cryogenic environment.

3. The system of claim 2, wherein the cold heat supply unit includes a cold heat supply line of methane, carbon monoxide, and nitrogen that connects the cryogenic separation device and the heat exchange unit, and a cold heat production device of the methane, carbon monoxide, and nitrogen that is equipped on a cold heat line of the methane, carbon monoxide, and nitrogen, receives the methane, the carbon monoxide, and the nitrogen gas separated by the cryogenic separation device in the cryogenic environment to cool the same, and supplies the same to the heat exchange unit.

4. The system of claim 3, wherein cold heat of the methane, the carbon monoxide, and the nitrogen gas produced in the cold heat production device of the methane, carbon monoxide, and nitrogen is transferred to the methane pyrolysis gas from which carbon black is removed, the steam methane reforming gas, and the ammonia decomposition gas that are supplied to the heat exchange unit.

5. The system of claim 3, wherein cold heat of the hydrogen gas separated by the cryogenic separation device in the cryogenic environment is transferred to the methane pyrolysis gas from which carbon black is removed, the steam methane reforming gas, and the ammonia decomposition gas that are supplied to the heat exchange unit, and the system further includes a storage unit that receives and stores the hydrogen gas after transferring the cold heat to the ammonia decomposition gas.

6. The system of claim 1, wherein the separation unit includes a plurality of cryogenic adsorption devices that receive the remaining gas and separate the remaining gas into the nitrogen gas and the hydrogen gas using an adsorbent, and the adsorbent includes a cryogenic adsorbent that increases the purity of separated gas by increasing an adsorption amount of the remaining gas by improving an adsorption performance in the cryogenic environment rather than in the non-cryogenic environment.

7. The system of claim 6, wherein the cold heat supply unit includes a hydrogen cold heat supply line that connects the cryogenic adsorption device and the heat exchange unit, and a hydrogen cold heat production device that is equipped on the hydrogen cold heat supply line and receives the hydrogen gas separated by the cryogenic adsorption device in the cryogenic environment to cool the same, and supplies the same to the heat exchange unit.

8. The system of claim 7, wherein cold heat of the hydrogen gas produced in the hydrogen cold heat production device is transferred to the methane pyrolysis gas from which carbon black is removed, the steam methane reforming gas, and the ammonia decomposition gas that are supplied to the heat exchange unit, and the system further includes a storage unit that receives and stores the hydrogen gas after transferring the cold heat to the methane pyrolysis gas from which carbon black is removed, the steam methane reforming gas, and the ammonia decomposition gas.

9. The system of claim 8, wherein at least a part of the hydrogen gas after transferring the cold heat to the methane pyrolysis gas from which carbon black is removed, the steam methane reforming gas, and the ammonia decomposition gas stored in the storage unit is selectively supplied to a plurality of the cryogenic adsorption devices to utilize for regenerating the adsorbent.

10. The system of claim 6, further including a degassing unit that receives the adsorbed gas adsorbed in the plurality of cryogenic adsorption devices to degas the same.

11. The system of claim 10, wherein the adsorbed gas degassed in the degassing unit is supplied to the heat exchange unit, and cold heat of the adsorbed gas supplied to the heat exchange unit is transferred to the methane pyrolysis gas from which carbon black is removed, the steam methane reforming gas, and the ammonia decomposition gas that are supplied to the heat exchange unit.

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