KR20230168726A - Hydrogen liquefying apparatus having open cycle of refrigerant hydrogen and hydrogen liquefying method using the same - Google Patents

Abstract

The present invention relates to a hydrogen liquefaction device having an open cycle of refrigerant hydrogen and a hydrogen liquefaction method using the same. The hydrogen liquefaction method according to the present invention first compresses supplied hydrogen gas and branches into refrigerant hydrogen and product hydrogen, performing secondary compression of the refrigerant hydrogen, and pre-cooling the secondarily compressed refrigerant hydrogen and the first compressed product hydrogen using liquefied nitrogen in a first heat exchange unit; The pre-cooled refrigerant hydrogen is branched into first refrigerant hydrogen and second refrigerant hydrogen, and the low-temperature energy generated by expanding the first refrigerant hydrogen is used to store the product hydrogen passing through the second heat exchange unit and the second refrigerant hydrogen. The second refrigerant hydrogen passing through the heat exchange unit is additionally cooled, and the low-temperature energy generated by expanding the additionally cooled second refrigerant hydrogen while first passing through the second heat exchange unit is introduced into the second heat exchange unit to produce the product hydrogen and A step of firstly liquefying the product hydrogen through a circulation cycle method of additionally cooling the second refrigerant hydrogen passing through the second heat exchange unit is provided.

Description

Hydrogen liquefaction device with open cycle of refrigerant hydrogen and hydrogen liquefaction method using the same {HYDROGEN LIQUEFYING APPARATUS HAVING OPEN CYCLE OF REFRIGERANT HYDROGEN AND HYDROGEN LIQUEFYING METHOD USING THE SAME}

The present invention relates to a hydrogen liquefaction device having an open cycle of refrigerant hydrogen and a hydrogen liquefaction method using the same. More specifically, the hydrogen liquefaction device has a simple process, high efficiency, and economical open cycle of refrigerant hydrogen, and a hydrogen liquefaction method using the same. It is about the liquefaction method.

As a way to solve the problems of air pollution and global warming caused by excessive use of fossil fuels, research is being actively conducted to use fuels other than hydrocarbons. A representative example is a method using hydrogen energy. Unlike hydrocarbon-based energy, hydrogen energy generates only water without emitting carbon dioxide during combustion, and hydrogen can be obtained again from water, so it can be classified as a renewable energy source.

Hydrogen energy is environmentally friendly and has high energy density, so it can be used as a fuel for fuel cells for automobiles and portable electronic devices. The price of fuel cells is also decreasing every year, so the era of hydrogen energy is advancing.

The most reasonable storage and transportation technology for hydrogen, which is currently mainly adopted in industry, is to liquefy hydrogen and store and transport it in the form of liquefied hydrogen with the highest energy density per volume, and to compress hydrogen at high pressure to increase energy density per weight. This is the best way to store and transport high-pressure gaseous hydrogen.

When gaseous hydrogen is cooled to -253°C at normal pressure, it is liquefied, and its density is about 780 times higher than that of gaseous hydrogen at normal pressure and about 1.75 times higher than that of hydrogen gas compressed at 700 bar. The storage pressure of liquefied hydrogen is usually less than 3 bar, which is advantageous in terms of safety compared to the high-pressure compressed gas method.

In terms of transportation method, when comparing the transportation efficiency of high-pressure gaseous hydrogen in the form of a high-pressure storage cylinder compressed to 200 bar and liquefied hydrogen, the liquefied transportation method is known to be about 10 times higher than the compressed hydrogen transportation method. there is.

In addition, a high-pressure compressor is required to compress hydrogen to high pressure, and a cryogenic refrigerator is required to liquefy hydrogen, resulting in costs associated with their installation and operation.

Therefore, according to economic analysis in terms of the entire value chain, including production, storage, and transportation, storing and transporting hydrogen in the form of liquefied hydrogen is known to be the most economical.

Although various devices and methods for liquefying hydrogen are known, there has been a demand for a hydrogen liquefaction method that is simple, efficient, and economical.

Republic of Korea Public Patent No. 10-2021-0052291 (2021.05.10)

Therefore, the purpose of the present invention is to provide a hydrogen liquefaction device using an open cycle of refrigerant hydrogen and a hydrogen liquefaction method using the same that can overcome the above-described conventional problems.

Another object of the present invention is to provide a hydrogen liquefaction device using an open cycle of refrigerant hydrogen that has a simple process, is highly efficient, and is economical, and a hydrogen liquefaction method using the same.

Another object of the present invention is to provide a hydrogen liquefaction device using an open cycle of refrigerant hydrogen that can recycle natural boil-off gas generated from liquefied hydrogen into refrigerant hydrogen, and a hydrogen liquefaction method using the same.

In accordance with the specification of the present invention to achieve some of the above-described technical problems, the hydrogen liquefaction method according to the present invention is that the supplied hydrogen gas is first compressed to a first pressure range through the first compression unit to produce refrigerant hydrogen and A first stage in which the product hydrogen is branched into product hydrogen and flows directly into the first heat exchange unit, and the refrigerant hydrogen is secondarily compressed to a second pressure range through a second compression unit and flows into the first heat exchange unit; a second step in which the product hydrogen and the refrigerant hydrogen are pre-cooled to a first temperature range by liquid nitrogen in the first heat exchange unit; The refrigerant hydrogen that has passed through the first heat exchanger is branched into first refrigerant hydrogen and second refrigerant hydrogen, and the first refrigerant hydrogen is expanded to a first pressure range through at least one expansion turbine and cooled to a second temperature range. flows into the second heat exchange unit, and supplies low-temperature energy to the second refrigerant hydrogen and the product hydrogen through heat exchange while passing through the second heat exchange unit, and the second refrigerant hydrogen passes through the second heat exchange unit first. It is liquefied in the second temperature range, expanded and further cooled through the first expansion valve, and vaporized while passing through the second heat exchanger secondarily in a gas-liquid mixed state of gas and liquid, and firstly passes through the second heat exchanger. A third step of supplying low-temperature energy to the second refrigerant hydrogen passing through the second refrigerant and supplying low-temperature energy to the product hydrogen passing through the second heat exchanger to liquefy it; Liquefied product hydrogen is stored in a storage tank, and the first refrigerant hydrogen supplies low-temperature energy while passing through the first heat exchanger and is recovered at room temperature in front of the second compression section to be recycled as the refrigerant hydrogen. The second refrigerant hydrogen supplies low-temperature energy while passing through the first heat exchanger, and is recovered at room temperature at the front of the first compression section to be recycled as supplied hydrogen gas.

The product hydrogen may undergo an ortho-para conversion reaction when passing through the second heat exchanger.

In the fourth step, before storing the liquefied hydrogen product in the storage tank, expanding the liquefied hydrogen product to atmospheric pressure through a second expansion valve; It may further include a gas-liquid separation step of separating gas and liquid from the product hydrogen expanded through the second expansion valve.

The natural vaporization gas (BOG: Boil Off Gas) generated in the storage tank storing the liquefied product hydrogen in the fourth step and the gaseous hydrogen separated through the gas-liquid separation step pass through the second heat exchanger secondly. It can be combined with the second refrigerant hydrogen and recycled as the supply hydrogen gas.

The first pressure range is 18 to 22 bar, the second pressure range is 60 to 70 bar, the first temperature range is a temperature range around the liquefaction temperature of nitrogen, and the second temperature range is -220 to -260 ° C. It can be.

In the third step, the first refrigerant hydrogen is supplied with low-temperature energy while first passing through the second heat exchanger; Heat is exchanged by being expanded to a first pressure range through at least one expansion turbine, cooled to a second temperature range, and supplied secondarily to the second heat exchanger, while passing through the second heat exchanger in a cooled state. Low-temperature energy can be supplied to the second refrigerant hydrogen and the product hydrogen.

In the third step, the first refrigerant hydrogen is cooled by receiving low-temperature energy while first passing through the second heat exchanger; Expanding and cooling through a first expansion turbine and supplying the second heat to the second heat exchanger; In the second order, low-temperature energy is supplied through the second heat exchanger, and in a re-cooled state, it is expanded and cooled through the second expansion turbine, and is finally cooled to the second temperature range while maintaining the first pressure range, and is then cooled to the second temperature range in the third order. Through the step of supplying to the heat exchanger, low-temperature energy can be supplied to the second refrigerant hydrogen and the product hydrogen through heat exchange while passing through the second heat exchanger in a cooled state for a third time.

In the second step, the liquid nitrogen is vaporized in the first heat exchanger to supply low-temperature energy for free cooling, and the vaporized nitrogen gas is liquefied again through a nitrogen liquefaction unit to resupply the liquid nitrogen to the first heat exchanger. There can be a cyclical process.

The first expansion valve may perform a flow rate control function when the first refrigerant hydrogen and the second refrigerant hydrogen branch, and the second expansion valve may perform a flow rate control function when the product hydrogen and the refrigerant hydrogen branch. there is.

According to another embodiment of the present invention for achieving some of the above technical problems, a hydrogen liquefaction device according to the present invention includes a hydrogen gas supply unit; a first compression unit that first compresses the hydrogen gas supplied from the hydrogen gas supply unit to a first pressure range; a first branch for branching the supplied hydrogen gas into refrigerant hydrogen and product hydrogen; a second compression unit for secondarily compressing the refrigerant hydrogen to a second pressure range; a first heat exchanger for pre-cooling the secondarily compressed refrigerant hydrogen and the firstly compressed product hydrogen to a first temperature range; a second branch unit for branching the refrigerant hydrogen that has passed through the first heat exchange unit into first refrigerant hydrogen and second refrigerant hydrogen; an expansion unit for expanding the first refrigerant hydrogen to a first pressure range and cooling it to a second temperature range; a second heat exchanger for supplying low-temperature energy to the product hydrogen to liquefy it through heat exchange between the first refrigerant hydrogen, the second refrigerant hydrogen, and the product hydrogen; Expanding and further cooling the second refrigerant hydrogen liquefied in the second temperature range while passing through the second heat exchanger firstly to convert it into a gas-liquid mixed state where gas and liquid are mixed, and passing the second heat exchanger secondly. A first expansion valve for; The first refrigerant hydrogen supplies low-temperature energy as it sequentially passes through the second heat exchange unit and the first heat exchange unit, and is recovered at room temperature in front of the second compression unit to be recycled as the refrigerant hydrogen. and; a second convergence unit where the second refrigerant hydrogen supplies low-temperature energy as it passes through the second heat exchange unit and the first heat exchange unit, and is recovered at room temperature in front of the first compression unit to be recycled as supplied hydrogen gas; It is provided with a storage tank for storing liquefied product hydrogen, and in the second heat exchange unit, the first refrigerant hydrogen that has passed through the expansion part passes through and supplies low-temperature energy to the second refrigerant hydrogen and the product hydrogen through heat exchange. And, the second refrigerant hydrogen is liquefied while passing through the first phase and vaporized while passing through the second phase, supplying low-temperature energy to the second refrigerant hydrogen passing through the second heat exchange section and passing through the second heat exchange section. Low-temperature energy is supplied to the product hydrogen to liquefy it.

It may include an Ortho-Para conversion catalyst for an Ortho-Para conversion reaction of the product hydrogen when passing through the second heat exchanger.

a second expansion valve that expands the liquefied hydrogen product to atmospheric pressure before storing the liquefied hydrogen product in the storage tank; It further includes a first gas-liquid separator that separates gas and liquid from the product hydrogen expanded through the second expansion valve, and the liquid hydrogen separated through the first gas-liquid separator is stored in the storage tank, and the first gas-liquid The gaseous hydrogen separated through the separator may be allowed to join the second refrigerant hydrogen that passes through the second heat exchanger secondarily.

A second gas-liquid separator may be further provided to separate gas-liquid from the second refrigerant hydrogen in a gas-liquid mixed state that has passed through the first expansion valve.

Natural vaporization gas (BOG: Boil Off Gas) generated in a storage tank storing the liquefied product hydrogen may join the second refrigerant hydrogen that passes through the second heat exchanger secondarily.

The expansion unit may include a first expansion turbine for expanding and cooling the first refrigerant hydrogen branched through the second branch unit.

The expansion unit includes a first expansion turbine that first expands and cools the first refrigerant hydrogen branched through the second branch to flow into the second heat exchange unit; A second expansion turbine may be provided to secondly expand and cool the supercooled first refrigerant hydrogen while passing through the second heat exchange unit after passing through the first expansion turbine and then flow it back into the second heat exchange unit. .

A nitrogen liquefaction device may be further provided to supply energy for free cooling from the first heat exchange unit, liquefy the vaporized nitrogen gas, and then introduce it back into the first heat exchange unit.

The first expansion valve may perform a flow rate control function when the first refrigerant hydrogen and the second refrigerant hydrogen branch, and the second expansion valve may perform a flow rate control function when the product hydrogen and the refrigerant hydrogen branch. there is.

According to another embodiment of the present invention for achieving some of the above-mentioned technical problems, the hydrogen liquefaction method according to the present invention first compresses the supply hydrogen gas and branches it into refrigerant hydrogen and product hydrogen, and the refrigerant hydrogen is Performing secondary compression and pre-cooling the secondarily compressed refrigerant hydrogen and the first compressed product hydrogen using liquefied nitrogen in the first heat exchange unit; The pre-cooled refrigerant hydrogen is branched into first refrigerant hydrogen and second refrigerant hydrogen, and the low-temperature energy generated by expanding the first refrigerant hydrogen is used to store the product hydrogen passing through the second heat exchange unit and the second refrigerant hydrogen. The second refrigerant hydrogen passing through the heat exchange unit is additionally cooled, and the low-temperature energy generated by expanding the additionally cooled second refrigerant hydrogen while first passing through the second heat exchange unit is introduced into the second heat exchange unit to produce the product hydrogen and A step of firstly liquefying the product hydrogen through a circulation cycle method of additionally cooling the second refrigerant hydrogen passing through the second heat exchange unit is provided.

The first refrigerant hydrogen is recycled as the refrigerant hydrogen after being heat-exchanged while sequentially passing through the first heat exchange unit - the second heat exchange unit - the second heat exchange unit - the first heat exchange unit, and the second refrigerant hydrogen is recycled to the first heat exchange unit. - After heat exchange while sequentially passing through the second heat exchanger - the second heat exchanger - the first heat exchanger, it is recycled as the supply hydrogen gas, and is a naturally vaporized gas (BOG: Boil) generated in the storage tank storing the liquefied product hydrogen. Off Gas) can be recycled as the supply hydrogen gas together with the second refrigerant hydrogen.

According to the present invention, the supplied hydrogen gas is branched into product hydrogen and refrigerant hydrogen, and the product hydrogen can be liquefied using the compression-cooling-expansion cycle of the refrigerant hydrogen, and the refrigerant hydrogen used in the cycle is It is possible to recycle it back into the product hydrogen or refrigerant hydrogen, and there is an advantage that it is possible to recycle the gas-liquid separation gas and natural vaporization gas generated from the liquefied product hydrogen into the product hydrogen or refrigerant hydrogen. Additionally, it has the advantage of reducing waste of refrigerant hydrogen and product hydrogen and improving energy efficiency. In addition, it has the advantage of enabling simple and economical hydrogen liquefaction using an open cycle.

1 and 2 are schematic flowcharts for a hydrogen liquefaction device and a hydrogen liquefaction method according to an embodiment of the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings, with no intention other than to provide a thorough understanding of the present invention to those skilled in the art to which the present invention pertains.

The meaning that each gaseous or liquid hydrogen described in the present invention has a first pressure range, a second pressure range, a first temperature range, or a second temperature range means that a specific pressure value or a specific temperature falling within that range This means that the pressure or temperature values of hydrogen performing different roles (e.g., first refrigerant hydrogen (RH1), second refrigerant hydrogen (RH2)) fall within that range. Being in the same pressure or temperature range does not mean that each hydrogen has the same pressure or temperature value. For example, assuming that the first refrigerant hydrogen (RH1) and the second refrigerant hydrogen (RH2) have a second temperature range, the first refrigerant hydrogen (RH1) and the second refrigerant hydrogen (RH2) have the same temperature within the second temperature range. It does not have a single value, but can have different temperature values within the second temperature range. In addition, the first temperature range may include the liquefaction temperature of nitrogen or a temperature range adjacent thereto, and the second temperature range may include the liquefaction temperature of hydrogen or a temperature range in which hydrogen can be liquefied at a constant pressure. there is. Additionally, the second temperature range may include the minimum temperature at which gaseous hydrogen can maintain its gaseous state at a constant pressure.

1 and 2 are schematic flowcharts for a hydrogen liquefaction device and a hydrogen liquefaction method according to an embodiment of the present invention. 1 and 2 have the same configuration except that the configuration of the expansion portion 134 is different.

As shown in FIGS. 1 and 2, the hydrogen liquefaction device 100 according to an embodiment of the present invention includes a hydrogen gas supply unit 110, a first compression unit (C1), a second compression unit (C2), and a hydrogen gas supply unit (110). First branch 112, first heat exchange part (E1), second branch part 132, expansion part 134, second heat exchange part (E2), first expansion valve 142, first confluence part ( 114), a second convergence part 116, and a storage tank 140 are provided to liquefy the product hydrogen by supplying low-temperature energy to the product hydrogen using a circulation method using compression, cooling, and expansion of the refrigerant hydrogen. Additionally, a second expansion valve 144, a first gas-liquid separator 146, and a second gas-liquid separator 148 may be further provided.

The hydrogen gas supply unit 110 supplies hydrogen gas for a refrigerant used as a refrigerant and hydrogen gas for a product to be supplied for liquefaction as supply hydrogen gas (FH). Here, the hydrogen gas for the refrigerant and the hydrogen gas for the product are not separated, and their purpose is determined by the supply hydrogen gas (FH) branching through the first branch 114. The supplied hydrogen gas (FH) supplied through the hydrogen gas supply unit 110 has a low pressure of approximately 1.2 bar.

The first compression unit (C1) is provided with a low-pressure hydrogen compressor to first compress the supply hydrogen gas (FH) supplied to the hydrogen gas supply unit 110 to a first pressure range. The first pressure range may be set to 18 to 22 bar, and preferably approximately 20 bar.

The first branch 112 supplies the supply hydrogen gas (FH) by branching it into refrigerant hydrogen (RH) and product hydrogen (PH). The branching ratio of the refrigerant hydrogen (RH) and the product hydrogen (PH) can be varied as needed, and the branching ratio of the refrigerant hydrogen (RH) and the product hydrogen (PH) is determined by the second expansion valve (144), which will be described later. ), or it can also be controlled through a separate flow control valve (not shown).

The second compression unit (C2) is provided with a high-pressure hydrogen compressor and secondly compresses the gaseous refrigerant hydrogen (RH) branched through the first branch unit (112) to a second pressure range. The second pressure range can be set to 60 to 70 bar, and can preferably be set to approximately 65 bar.

The first heat exchange unit (E1) has at least one heat exchanger, and the refrigerant hydrogen (RH) is secondarily compressed through the second compression unit (C2) and the refrigerant hydrogen (RH) is compressed through the first compression unit (C1). The primarily compressed product hydrogen (PH) is pre-cooled to a first temperature range through heat exchange with liquid nitrogen, the main coolant. The first temperature range may include a temperature of approximately -196°C, which is the liquefaction temperature of nitrogen, or a temperature range of approximately -180 to -196°C (around 80K), which is an adjacent range thereof.

The liquid nitrogen supplies low-temperature energy to the refrigerant hydrogen (RH) and the product hydrogen (PH) through heat exchange in the first heat exchange unit (E1) and is converted to gaseous nitrogen at room temperature, and is converted into gaseous nitrogen at room temperature through a nitrogen liquefaction unit (120). It is liquefied again and flows into the first heat exchange unit (E1), and is circulated in such a way that low-temperature energy is supplied to the refrigerant hydrogen (RH) and the product hydrogen (PH) in the first heat exchange unit (E1). .

In the first heat exchange unit (E1), the refrigerant hydrogen (RH) and the product hydrogen (PH) are cooled through heat exchange using the liquid nitrogen as the main coolant, but additionally, the refrigerant hydrogen (RH) and the product hydrogen (PH) are combined into the first convergence unit (114). First refrigerant hydrogen (RH1) passing through the first heat exchange unit (E1) and second refrigerant hydrogen (RH2) passing through the first heat exchange unit (E1) to join the second convergence unit (116). Heat exchange is performed by supplying low-temperature energy to the refrigerant hydrogen (RH) and the product hydrogen (PH) using as a secondary coolant.

At this time, the first refrigerant hydrogen (RH1) and the second refrigerant hydrogen before passing through the first heat exchange unit (E1) have approximately a first temperature range and exchange heat while passing through the first heat exchange unit (E1). It becomes at room temperature and merges into the first convergence part 114 or the second convergence part 116.

The second branch unit 132 branches the refrigerant hydrogen (RH) that has passed through the first heat exchange unit (E1) into first refrigerant hydrogen (RH1) and second refrigerant hydrogen (RH2).

The second branch portion 132 may be provided at the front of the second heat exchanger (E2) or may be provided inside the second heat exchanger (E2). When the second branch 132 is provided at the front of the second heat exchanger (E2), the pre-cooled refrigerant hydrogen (RH) is branched into first refrigerant hydrogen (RH1) and second refrigerant hydrogen (RH2). , when the second branch portion 132 is provided inside the second heat exchanger (E2), the refrigerant hydrogen (RH) is pre-cooled and then passes through the second heat exchanger (E2) and is further cooled. It has a configuration that branches out into the first refrigerant hydrogen (RH1) and the second refrigerant hydrogen (RH2), thereby increasing the efficiency of the refrigerant.

The expansion unit 134 is used to expand the first refrigerant hydrogen (RH1) to a first pressure range and cool it to a second temperature range, and may be provided with at least one expansion turbine (T11, T12, T13). In the expansion unit 134, the pressure of the first refrigerant hydrogen (RH1) is lowered to the first pressure range and the temperature is lowered to the second temperature range due to adiabatic expansion or isentropic expansion.

The first refrigerant hydrogen (RH1) branched from the second branch 132 has a first temperature range and a second pressure range, and expands through the expansion part 134 to approximately reach a first pressure. range and cooled to a second temperature range (e.g., a temperature around -230°C). The first refrigerant hydrogen (RH1) is in a gaseous state, but may also be in a gas-liquid mixed state, that is, a gas-liquid mixed state.

Here, it has already been described that the first pressure range can be set to 18 to 22 bar, and preferably set to approximately 20 bar. Additionally, the second temperature range may be set to a temperature range of -220 to -260°C (approximately, around 40K). In general, the liquefaction temperature of hydrogen is -253℃, but in the case of a constant pressure, that is, in the first pressure range of approximately 20 bar, the liquefaction or gas-liquid mixed state is maintained even if the temperature is higher than the liquefaction temperature of hydrogen, -253℃. It becomes possible.

As shown in FIG. 1, the expansion unit 134 is provided with first expansion turbines (T11 and T12) for expanding the first refrigerant hydrogen (RH1) branched through the second branch unit 132. can do. In this case, the first refrigerant hydrogen (RH1) is cooled by receiving low-temperature energy while first passing through the second heat exchange unit (E2), and then first refrigerant hydrogen (RH1) is cooled by receiving low-temperature energy through the first expansion turbines (T11 and T12). It is expanded to a pressure range, cooled to a second temperature range, and supplied secondarily to the second heat exchanger, and supplies low-temperature energy as it passes through the second heat exchanger (E2). Here, the first refrigerant hydrogen (RH1) receives low-temperature energy when it first passes through the second heat exchange unit (E2), and receives low-temperature energy when it passes through the second heat exchange unit (E2). It has a configuration that is supplied.

According to another embodiment, as shown in FIG. 2, the expansion unit 134 first expands the first refrigerant hydrogen (RH1) branched through the second branch unit 132 to perform the second heat exchange. At least one first expansion turbine (T11, T12) that flows into the unit (E2), and the first expansion turbine (T11, T12) and then supercooled while passing through the second heat exchange unit (E2). It may have a configuration including a second expansion turbine (T13) to expand the first refrigerant hydrogen (RH1) to a second stage and allow it to flow back into the second heat exchange unit (E2).

In this case, the first refrigerant hydrogen (RH1) is cooled by receiving low-temperature energy while first passing through the second heat exchange unit (E2), and then expands through the first expansion turbines (T11 and T12). and can be supplied to the second heat exchanger (E2) in a cooled state. Then, it is supplied to the second heat exchanger (E2), receives low-temperature energy through the second heat exchanger (E2), is re-cooled, and expands through the second expansion turbine (T13) to finally It is cooled to the first pressure range and the second temperature range and goes through a third process of being supplied to the second heat exchanger, and a third process of supplying low-temperature energy while passing through the second heat exchanger (E2) and being vaporized. You can go through Here, the first refrigerant hydrogen (RH1) is supplied with low-temperature energy when it passes through the second heat exchange unit (E2) in the first and second passes, and when it passes through the second heat exchange unit (E2) in the third pass. It has a configuration that supplies low-temperature energy.

Here, in order for the first refrigerant hydrogen (RH1) to efficiently perform its role as a refrigerant, the expansion turbine may be added or subtracted as necessary, and the first expansion turbine (T11, T12) and the second expansion turbine (T13) ) may include a process of passing through the second heat exchanger (E2), and the first expansion turbine (T11, T12) and the second expansion turbine (T11, T12) without passing through the second heat exchanger (E2). It is also possible to allow the expansion process through T13) to be performed continuously.

As a result, the first refrigerant hydrogen (RH1) passing through the expansion unit 134 is in a gaseous state or a gas-liquid mixture state having a first pressure range and a second temperature range.

The second heat exchange unit (E2) has at least one heat exchanger, and heat exchanges between the first refrigerant hydrogen (RH1), the second refrigerant hydrogen (RH2), and the product hydrogen (PH) to produce the product hydrogen (PH). ) to liquefy the product hydrogen (PH) by supplying low-temperature energy to the product.

In the second heat exchange unit (E2), the cooled first refrigerant hydrogen (RH1) passes through the expansion unit 134, and the second refrigerant hydrogen passes through the second heat exchange unit (E2) through heat exchange. Low-temperature energy is supplied to (RH2) and the product hydrogen (PH).

In addition, the second refrigerant hydrogen (RH2) branched through the second branch portion 132 passes through the second heat exchange portion (E2) in the first direction (or in the forward direction) and the first refrigerant hydrogen (RH1) It is liquefied by receiving low-temperature energy from. The second refrigerant hydrogen (RH2) is cooled and is in a liquefied state. The second pressure range, which is the pressure range of the second refrigerant hydrogen (RH2), is 60 to 70 bar, and the second refrigerant hydrogen (RH2) in a high pressure state has a temperature relatively higher than -253°C, which is the liquefaction temperature of hydrogen. (For example, it can be easily liquefied at approximately -235 to -250℃).

The liquefied second refrigerant hydrogen (RH2) is vaporized again while passing through the second heat exchanger (E2) in the second lane (or in the reverse direction), and passes through the second heat exchanger (E2) in the first lane (or in the forward direction). ) supplies low-temperature energy to the second refrigerant hydrogen (RH2) passing through the second heat exchanger (E2) and also supplies low-temperature energy to the product hydrogen (PH) passing through the second heat exchange unit (E2) to liquefy it. .

As a result, in the second heat exchange unit (E2), the low-temperature energy obtained through the cooling process through expansion of the compressed first refrigerant hydrogen (RH1) or the cooling process through cooling-expansion, and the compressed second refrigerant hydrogen (RH1) The low-temperature energy obtained through the cooling-expansion of the refrigerant hydrogen (RH2) is used to supply low-temperature energy to the product hydrogen (PH) to liquefy it.

Additionally, when the product hydrogen (PH) passes through the second heat exchange unit (E2), an ortho-para conversion catalyst for the ortho-para conversion reaction of the product hydrogen (PH) may be provided. You can. The Ortho-Para conversion reaction of the product hydrogen (PH) is an exothermic reaction, and the heat generated during the Ortho-Para conversion reaction is generated in the second heat exchange unit (E2). It is possible to resolve this through heat exchange.

The first expansion valve 142 expands and further cools the second refrigerant hydrogen (RH2) liquefied in the second temperature range while passing through the second heat exchange unit (E2) in the first direction (or in the forward direction) to gas. and converting the liquid into a gas-liquid mixed state to pass through the second heat exchanger (E2) again in the second lane (or in the reverse direction). That is, the second refrigerant hydrogen (RH2) is in a gas-liquid mixed state at a lower temperature than the temperature of the liquefied state immediately after passing through the second heat exchanger (E2) in the first lane (or in the reverse direction) in the second lane (or in the reverse direction). ) passes through the second heat exchange unit (E2). The second refrigerant hydrogen (RH2) that has passed through the first expansion valve 142 may have a pressure range of about 1 to 3 bar, which is close to atmospheric pressure.

In addition, the first expansion valve 142 may perform a flow rate control function when the first refrigerant hydrogen (RH1) and the second refrigerant hydrogen (RH2) branch through the second branch 132. If necessary, a separate flow control valve may be provided.

When the second refrigerant hydrogen (RH2) passes through the second heat exchange unit (E2) in the first lane (or in the forward direction), the first refrigerant hydrogen (RH1) and the second heat exchange unit (RH1) in the second lane (or in the reverse direction). It is liquefied by obtaining low-temperature energy from the second refrigerant hydrogen (RH2) passing through (E2), and passes through the second heat exchanger (E2) in the second lane (or in the reverse direction) in the first lane (or in the forward direction). Low-temperature energy is supplied to the second refrigerant hydrogen (RH2) and the product hydrogen (PH) passing through the second heat exchange unit (E2).

The first convergence part 114 generates low-temperature energy as the first refrigerant hydrogen (RH1), which has passed through the expansion part 134, sequentially passes through the second heat exchange part (E2) and the first heat exchange part (E1). This is to supply and recover the gaseous state at room temperature to the front of the second compression section (C2) and recycle it as the refrigerant hydrogen (RH). Since the first refrigerant hydrogen (RH1) joining the first convergence section 114 has a gaseous state in the first pressure range, the second compression section (C2) does not need to go through the first compression section (C1). It can join the front end and be recycled into the refrigerant hydrogen (RH).

The second convergence part 116 supplies low-temperature energy as the second refrigerant hydrogen (RH2) passes through the second heat exchange part (E2) in the second direction (or in the reverse direction), and then returns to the first heat exchange part (E1). ) to supply low-temperature energy while passing through the heat exchanger, and through this heat exchange, the gaseous state at room temperature is recovered to the front of the first compression section (C1) and recycled as supplied hydrogen gas. The second refrigerant hydrogen (RH2) joining the second confluence unit 116 has a pressure range of about 1 to 3 bar, close to atmospheric pressure, and is connected to the supply hydrogen gas supplied through the hydrogen gas supply unit 110. Since it has a similar pressure range, it is recovered at the front of the first compression section (C1) and recycled as supply hydrogen gas.

The storage tank 140 is for storing product hydrogen (PH) liquefied by receiving low-temperature energy while passing through the second heat exchange unit (E2).

Before storing the liquefied product hydrogen (PH) in the storage tank 140 while passing through the second heat exchange unit (E2), the second expansion valve 144 stores the liquefied product hydrogen at atmospheric pressure level or close to atmospheric pressure. This is to expand it to the level of 1 to 3 bar. In addition, the second expansion valve 144 may perform a flow rate control function when the refrigerant hydrogen (RH) and the product hydrogen (RH2) branch through the first branch 112. If necessary, a separate flow control valve may be provided.

Product hydrogen (PH) liquefied while passing through the second heat exchange unit (E2) has a first pressure range, and storage tanks for storing high-pressure liquefied hydrogen are expensive and high-pressure liquefied hydrogen is difficult to manage. Therefore, before storing the liquefied hydrogen product (PH) in the storage tank 140, it is necessary to expand the liquefied hydrogen product to a level of 1 to 3 bar, which is at or close to atmospheric pressure. Product hydrogen (PH) expanded through the second expansion valve 144 requires gas-liquid separation because some of the liquefied hydrogen vaporizes during the expansion process.

The first gas-liquid separator 146 separates gas and liquid from the product hydrogen (PH) expanded through the second expansion valve 144, and the separated liquid hydrogen is supplied to the storage tank 140 and separated. The gaseous hydrogen is joined to the second refrigerant hydrogen (RH2) passing through the second heat exchange unit (E2) in the second direction (or in the reverse direction) through the third confluence section (138) to form the second refrigerant hydrogen (RH2). ) and supplies low-temperature energy while passing through the second heat exchange unit (E2) in the second lane (or in the reverse direction). The third confluence portion 138 may be provided before the second refrigerant hydrogen (RH2) flows into the second heat exchanger (E2) in the second lane (or in the reverse direction), and the second refrigerant hydrogen ( It is also possible that RH2) is provided on the line immediately after flowing into the second heat exchanger (E2) in the second lane (or in the reverse direction).

In addition, natural vaporization gas (BOG: Boil Off Gas) generated in the storage tank 140 storing the liquefied product hydrogen (PH) passes through the second heat exchange unit (E2) in the second lane (or in the reverse direction). It joins the second refrigerant hydrogen (RH2) and supplies low-temperature energy while passing through the second heat exchange unit (E2) in the second lane (or in the reverse direction) together with the second refrigerant hydrogen (RH2).

Accordingly, the natural vaporization gas (BOG: Boil Off Gas) generated from the liquefied product hydrogen (PH) and the gaseous hydrogen of the product hydrogen (PH) separated from the first gas-liquid separator 146 are the second refrigerant hydrogen ( RH2) and passes through the second heat exchange unit (E2), supplying low-temperature energy and contributing to the liquefaction of product hydrogen (PH).

Additionally, the second gas-liquid separator 148 is for gas-liquid separation of the second refrigerant hydrogen (RH2) in a gas-liquid mixed state that has passed through the first expansion valve 142, and the separated liquid and gas are passed through a separate line. They join at the third convergence part 138 and supply low-temperature energy while passing through the second heat exchange part E2 in the second direction (or in the reverse direction). The second gas-liquid separator 148 is intended to take advantage of the characteristic that heat distribution efficiency is improved when liquid and gas are separated and transported, and may not be provided as needed. If the second gas-liquid separator 148 is not provided, the second refrigerant hydrogen (RH2) in a gas-liquid mixed state that has passed through the first expansion valve 142 is directly transferred to the second heat exchange unit (E2) as a second lane (or As it passes in the reverse direction, low-temperature energy is supplied.

The hydrogen liquefaction process using the hydrogen liquefaction device having the above-described configuration will be described with reference to FIGS. 1 and 2 as follows.

The hydrogen liquefaction process can be largely divided into a pre-cooling process through the first heat exchanger (E1) and a liquefaction process of product hydrogen through the second heat exchanger (E2).

In the precooling process, the supply hydrogen gas (FH) is first compressed to branch into refrigerant hydrogen (RH) and product hydrogen (PH), and the refrigerant hydrogen (RH) is secondarily compressed to produce a second compressed gas. This is a process of pre-cooling refrigerant hydrogen (RH) and first compressed product hydrogen (PH) using liquefied nitrogen (LN) in the first heat exchange unit (E1).

In addition, the liquefaction process branches the pre-cooled refrigerant hydrogen (RH) into first refrigerant hydrogen (RH1) and second refrigerant hydrogen (RH2), and expands the first refrigerant hydrogen (RH1) to generate low-temperature energy. The product hydrogen (PH) passing through the second heat exchange unit (E2) and the second refrigerant hydrogen (RH2) passing through the second heat exchange unit in the first direction (or in the forward direction) are further cooled using The low-temperature energy generated by expanding the additionally cooled second refrigerant hydrogen (RH2) while passing through the unit (E2) in the first lane (or in the forward direction) flows into the second heat exchange unit (E2) to produce the product hydrogen (PH ) and the second refrigerant hydrogen (RH1) passing through the first lane (or forward direction) second heat exchanger is a process of liquefying the product hydrogen (PH) through a circulation cycle that further cools the second refrigerant hydrogen (RH1). At this time, the first refrigerant hydrogen (RH1) is heat exchanged while sequentially passing through the first heat exchange unit (E1) - the second heat exchange unit (E2) - the second heat exchange unit (E2) - the first heat exchange unit (E1). It is recycled as the refrigerant hydrogen (RH), and the second refrigerant hydrogen (RH2) is divided into the first heat exchange part (E1) - the second heat exchange part (E2) - the second heat exchange part (E2) - the first heat exchange part (E1) ) is recycled as the supply hydrogen gas (FH) after heat exchange while sequentially passing through the supply hydrogen gas (FH), and the natural vaporization gas generated from the liquefied product hydrogen (PH) is also supplied with the supply hydrogen gas (RH2) together with the second refrigerant hydrogen (RH2) FH) goes through a recycling process.

Looking in more detail, first, the supply hydrogen gas (FH) supplied through the hydrogen gas supply unit 110 is first compressed to a first pressure range through the first compression unit (C1) and is in a gaseous state (gas state). It branches into refrigerant hydrogen (RH) and gaseous product hydrogen (PH). And the gaseous product hydrogen (PH) flows directly into the first heat exchange unit (E1), and the gaseous refrigerant hydrogen (RH) is adjusted to the second pressure range through the second compression unit (C2). It is secondarily compressed and flows into the first heat exchange unit (E1).

In the first heat exchange part (E1), the refrigerant hydrogen (RH) secondarily compressed through the second compression part (C2) and the product hydrogen (RH) first compressed through the first compression part (C1) PH) is pre-cooled to the first temperature range through heat exchange with liquid nitrogen, the main coolant. Here, the first heat exchange unit (E1) cools the refrigerant hydrogen (RH) and the product hydrogen (PH) through heat exchange using liquid nitrogen as the main coolant, but additionally, the first convergence unit (114) The first refrigerant hydrogen (RH1) recovered while passing through the first heat exchange unit (E1) to join and the refrigerant hydrogen (RH1) recovered while passing through the first heat exchange unit (E1) to join the second confluence unit (116). 2. Cooling heat exchange is performed by using refrigerant hydrogen (RH2) as a secondary coolant and supplying low-temperature energy to the refrigerant hydrogen (RH) and the product hydrogen (PH).

The gaseous product hydrogen (PH) pre-cooled to the first temperature range through the first heat exchange unit (E1) passes through the second heat exchange unit (E2) and is converted into the first refrigerant hydrogen (RH1) and the It is liquefied by receiving low-temperature energy from the second refrigerant hydrogen (RH2). In addition, the product hydrogen (PH) undergoes an ortho-para conversion reaction while passing through the second heat exchange unit (E2), and the heat generated in this process is generated at a low temperature of the second heat exchange unit (E2). It is offset by energy.

The gaseous refrigerant hydrogen (RH) pre-cooled to a first temperature range while passing through the first heat exchange unit (E1) is divided into the first refrigerant hydrogen (RH1) and the second refrigerant hydrogen (RH1) in the second branch portion (132). It branches off into refrigerant hydrogen (RH2). It has already been described that the second branch portion 132 may be provided inside the second heat exchanger (E2) or may be provided at the front of the second heat exchanger (E2). When the second branch 132 is provided inside the second heat exchanger (E2), the refrigerant hydrogen (RH) is pre-cooled and then passes through the second heat exchanger (E2) in an additional cooled state. It has a configuration that branches into the first refrigerant hydrogen (RH1) and the second refrigerant hydrogen (RH2), thereby increasing the efficiency of the refrigerant.

The branched first refrigerant hydrogen (RH1) is expanded to the first pressure range through the expansion unit 134, cooled to the second temperature range, becomes a gas state or a gas-liquid mixture state, and flows into the second heat exchanger (E2). And, while passing through the second heat exchange unit (E2), low-temperature energy is supplied to the second refrigerant hydrogen (RH2) and the product hydrogen (PH). After passing through the second heat exchange unit (E2), the first refrigerant hydrogen (RH1) has a first pressure range and a first temperature range in a gaseous state.

The branched second refrigerant hydrogen (RH2) is in a gaseous state having a second pressure range and a first temperature range, and passes through the second heat exchange unit (E2) in the first lane (or in the forward direction) to reach the second pressure range and It is liquefied in the second temperature range. At this time, the second refrigerant hydrogen (RH2) receives low-temperature energy from the first refrigerant hydrogen (RH1), which is liquefied through the expansion unit 134 and flows into the second heat exchange unit (E2), and also undergoes gas-liquid mixing. It is liquefied by receiving low-temperature energy from the second refrigerant hydrogen (RH2) passing through the second heat exchanger (E2) in the second lane (or in the reverse direction).

The second refrigerant hydrogen (RH2) liquefied in the second temperature range while passing through the second heat exchange unit (E2) in the first direction (or in the forward direction) is expanded and further cooled through the first expansion valve 142 to become gas. And the liquid is converted into a gas-liquid mixed state, and is allowed to pass through the second heat exchanger (E2) again in a second direction (or in the reverse direction). The second refrigerant hydrogen (RH2) that has passed through the first expansion valve 142 has a pressure range of about 1 to 3 bar, which is close to atmospheric pressure, and may have a second temperature range.

The second refrigerant hydrogen (RH2) in a gas-liquid mixed state that has passed through the first expansion valve 142 is vaporized while passing through the second heat exchanger (E2) again in the second lane (or in the reverse direction), and then in the first lane. (or in the forward direction) supplies low-temperature energy to the second refrigerant hydrogen (RH2) passing through the second heat exchange unit (E2) and also to the product hydrogen (PH) passing through the second heat exchange unit (E2). Low-temperature energy is supplied to liquefy the product hydrogen (PH). After passing through the second heat exchange unit (E2) in the second direction (or in the reverse direction), the second refrigerant hydrogen (RH2) has a pressure range and a first temperature range close to atmospheric pressure in the gaseous state.

When the second refrigerant hydrogen (RH2) passes through the second heat exchange unit (E2) in the first lane (or in the forward direction), the first refrigerant hydrogen (RH1) and the second heat exchange unit (RH1) in the second lane (or in the reverse direction). It is liquefied by obtaining low-temperature energy from the second refrigerant hydrogen (RH2) in a gas-liquid mixed state passing through (E2), and passes through the second heat exchange unit (E2) in the second lane (or in the reverse direction) in the first lane (or In the forward direction), low-temperature energy is supplied to the gaseous second refrigerant hydrogen (RH2) and the product hydrogen (PH) passing through the second heat exchange unit (E2) to liquefy them.

As a result, in the second heat exchange unit (E2), the low-temperature energy obtained through the cooling process through expansion of the compressed first refrigerant hydrogen (RH1) or the cooling process through cooling-expansion, and the compressed second refrigerant hydrogen (RH1) The low-temperature energy obtained through the cooling-expansion of the refrigerant hydrogen (RH2) is used to supply low-temperature energy to the product hydrogen (PH) to liquefy it.

Meanwhile, while passing through the second heat exchange unit (E2), low-temperature energy is supplied to the second refrigerant hydrogen (RH2) and the product hydrogen (PH), so that the refrigerant has a first pressure range and a first temperature range in a gaseous state. 1 Refrigerant hydrogen (RH1) functions as a sub-coolant while passing through the first heat exchange unit (E1) in the reverse direction, and the refrigerant hydrogen (RH) and the product hydrogen pass through the first heat exchange unit (E1) in the forward direction. Low-temperature energy is supplied to (PH), and recovered in the gaseous state at room temperature and in the first pressure range to the first convergence section 114, which is the front end of the second compression section C2, to be recycled as the refrigerant hydrogen (RH). do.

While passing through the second heat exchanger (E2) in the second direction (or in the reverse direction), low-temperature energy is supplied to the second refrigerant hydrogen (RH2) and the product hydrogen (PH), thereby maintaining a pressure range close to atmospheric pressure in the gaseous state and The second refrigerant hydrogen (RH2), which has a first temperature range, passes through the first heat exchange unit (E1) in the reverse direction and the refrigerant hydrogen (RH) which passes through the first heat exchange unit (E1) in the forward direction, and Low-temperature energy is supplied to the product hydrogen (PH), and it is supplied to the second convergence section 116, which is the front end of the first compression section C1, in a pressure range close to atmospheric pressure in the gaseous state at room temperature. It is recycled as hydrogen gas (FH).

The product hydrogen (PH) liquefied while passing through the second heat exchange unit (E2) is stored in the storage tank 140, and before storing it in the storage tank 140, the second expansion valve 144 is used. Therefore, it may be necessary to expand the liquefied product hydrogen to a level of 1 to 3 bar, which is at or close to atmospheric pressure. Product hydrogen (PH) liquefied while passing through the second heat exchange unit (E2) has a first pressure range, and storage tanks for storing high-pressure liquefied hydrogen are expensive and high-pressure liquefied hydrogen is difficult to manage. Therefore, before storing the liquefied product hydrogen (PH) in the storage tank 140, it may be necessary to expand the liquefied product hydrogen to a level of 1 to 3 bar, which is at or close to atmospheric pressure.

In addition, the product hydrogen (PH) expanded through the second expansion valve 144 requires gas-liquid separation because some of the liquefied hydrogen vaporizes during the expansion process, and gas and liquid are separated through the first gas-liquid separator 146. is separated, the separated liquid hydrogen is supplied to the storage tank 140, and the separated gaseous hydrogen (or gaseous hydrogen) passes through the second heat exchanger (E2) in the second direction (or in the reverse direction). It joins the second refrigerant hydrogen (RH2) and supplies low-temperature energy while passing through the second heat exchange unit (E2) in the second lane (or in the reverse direction) together with the second refrigerant hydrogen (RH2).

In addition, natural vaporization gas (BOG: Boil Off Gas) generated in the storage tank 140 storing the liquefied product hydrogen (PH) passes through the second heat exchange unit (E2) in the second lane (or in the reverse direction). It joins the second refrigerant hydrogen (RH2) and supplies low-temperature energy while passing through the second heat exchange unit (E2) in the second lane (or in the reverse direction) together with the second refrigerant hydrogen (RH2).

Accordingly, the natural vaporization gas (BOG: Boil Off Gas) generated from the liquefied product hydrogen (PH) and the vaporization gas of the product hydrogen (PH) separated from the first gas-liquid separator 146, the second refrigerant hydrogen ( RH2) and passes through the second heat exchange unit (E2), supplying low-temperature energy and contributing to the liquefaction of product hydrogen (PH).

Additionally, a process of separating the second refrigerant hydrogen (RH2) in a gas-liquid mixed state that has passed through the first expansion valve 142 through the second gas-liquid separator 148 may be necessary, and the second gas-liquid separator 148 The liquid and gas separated through are transferred through a separate line, join the second refrigerant hydrogen (RH2) in the third convergence part (138), and supply low-temperature energy while passing through the second heat exchange part (E2). I do it.

As a result, in relation to the product hydrogen (PH), the supply hydrogen gas (FH) supplied from the hydrogen gas supply unit 110 is divided into product hydrogen (PH) and refrigerant hydrogen (RH), and the product hydrogen (PH ) is pre-cooled by receiving low-temperature energy while passing through the first heat exchanger (E1), and is liquefied by receiving low-temperature energy while passing through the second heat exchanger (E2), and the liquefied product hydrogen (PH) is stored in the storage tank. It is stored and utilized in (140), and vaporized gas generated through gas-liquid separation in a liquefied state and natural vaporized gas (BOG: Boil Off Gas) generated in the storage tank 140 are converted into the supplied hydrogen gas (FH). It goes through a recycling cycle. Accordingly, the waste of hydrogen that may occur due to vaporization can be reduced, and the vaporized gas and the natural vaporized gas (BOG: Boil Off Gas) generated through gas-liquid separation have a second temperature range in the second heat exchanger. Since low-temperature energy is supplied through (E2), energy efficiency can be improved.

In addition, in relation to the first refrigerant hydrogen (RH1), the supply hydrogen gas (FH) supplied from the hydrogen gas supply unit 110 is divided into product hydrogen (PH) and refrigerant hydrogen (RH), and the refrigerant hydrogen ( RH) receives low-temperature energy while passing through the first heat exchange unit (E1) and is pre-cooled, and the pre-cooled refrigerant hydrogen (RH) branches into first refrigerant hydrogen (RH1) and second refrigerant hydrogen (RH2). , the first refrigerant hydrogen (RH1) is cooled while expanding through the expansion part 134, and supplies low-temperature energy while sequentially passing through the second heat exchange part (E2) and the first heat exchange part (E1). It is recovered to the first confluence section 114 and goes through a circulation process in which it is recycled as the refrigerant hydrogen (RH). Accordingly, waste of refrigerant hydrogen (RH) can be reduced and energy efficiency can be improved.

In addition, in relation to the second refrigerant hydrogen (RH2), the supply hydrogen gas (FH) supplied from the hydrogen gas supply unit 110 is divided into product hydrogen (PH) and refrigerant hydrogen (RH), and the refrigerant hydrogen ( RH) receives low-temperature energy while passing through the first heat exchange unit (E1) and is pre-cooled, and the pre-cooled refrigerant hydrogen (RH) branches into first refrigerant hydrogen (RH1) and second refrigerant hydrogen (RH2). , the second refrigerant hydrogen (RH1) is liquefied by receiving low-temperature energy while passing through the second heat exchange unit (E2) in the first direction (forward direction), and is expanded through the first expansion valve 142 to enter a gas-liquid mixed state. , supplying low-temperature energy through heat exchange while passing through the second heat exchange unit (E2) in the second direction (in the reverse direction), and supplying low-temperature energy while passing through the first heat exchange unit (E1) in the reverse direction. It joins the second confluence section 116 and goes through a circulation process in which it is recycled as the supply hydrogen gas (FH). Accordingly, waste of refrigerant hydrogen (RH) can be reduced and energy efficiency can be improved.

According to the present invention, the supplied hydrogen gas is branched into product hydrogen and refrigerant hydrogen, and the product hydrogen can be liquefied using the cycle cycle of compression-cooling-expansion of the refrigerant hydrogen, and the refrigerant hydrogen used in the cycle is It is possible to recycle it back into the product hydrogen or refrigerant hydrogen, and there is an advantage that it is possible to recycle the gas-liquid separation gas and natural vaporization gas generated from the liquefied product hydrogen into the product hydrogen or refrigerant hydrogen. Additionally, it has the advantage of reducing waste of refrigerant hydrogen and product hydrogen and improving energy efficiency. In addition, it has the advantage of enabling simple and economical hydrogen liquefaction by using an open cycle rather than a closed cycle.

The description of the above-described embodiment is merely an example with reference to the drawings for a more thorough understanding of the present invention, and should not be construed as limiting the present invention. In addition, it will be clear to those skilled in the art that various changes and modifications can be made without departing from the basic principles of the present invention.

110: Hydrogen gas supply section 112: First branch section
114: first confluence section 116: second confluence section
120: Nitrogen liquefaction device 132: Second branch section
134: expansion part 138; 3rd confluence
140: storage tank 142: first expansion valve
144: second expansion valve 146: first gas-liquid separator
148: Second gas-liquid separator C1: First compression unit
C2: Second compression section E1: First heat exchange section
E2: 2nd heat exchange unit

Claims (20)

The supplied hydrogen gas is first compressed to a first pressure range through the first compression unit and splits into refrigerant hydrogen and product hydrogen, the product hydrogen flows directly into the first heat exchange unit, and the refrigerant hydrogen flows through the second compression unit. A first stage in which secondary compression is performed to a second pressure range and flows into the first heat exchanger;
a second step in which the product hydrogen and the refrigerant hydrogen are pre-cooled to a first temperature range by liquid nitrogen in the first heat exchange unit;
The refrigerant hydrogen that has passed through the first heat exchanger is branched into first refrigerant hydrogen and second refrigerant hydrogen, and the first refrigerant hydrogen is expanded to a first pressure range through at least one expansion turbine and cooled to a second temperature range. flows into the second heat exchanger, and supplies low-temperature energy to the second refrigerant hydrogen and the product hydrogen through heat exchange while passing through the second heat exchanger,
The second refrigerant hydrogen is liquefied in a second temperature range while first passing through the second heat exchanger, and is expanded and further cooled through the first expansion valve to form a gas-liquid mixed state of the second heat exchanger. A third step of supplying low-temperature energy to the second refrigerant hydrogen passing through the second heat exchanger, which is vaporized while passing through the second heat exchanger, and supplying low-temperature energy to the product hydrogen passing through the second heat exchanger to liquefy it. and;
Liquefied product hydrogen is stored in a storage tank, and the first refrigerant hydrogen supplies low-temperature energy while passing through the first heat exchanger and is recovered at room temperature in front of the second compression section to be recycled as the refrigerant hydrogen. A hydrogen liquefaction method characterized by a fourth step in which the second refrigerant hydrogen supplies low-temperature energy while passing through the first heat exchange unit, is recovered at room temperature at the front of the first compression unit, and is recycled as supplied hydrogen gas. In claim 1,
A hydrogen liquefaction method, characterized in that the product hydrogen undergoes an ortho-para conversion reaction when passing through the second heat exchanger. In claim 1,
In the fourth step, before storing the liquefied hydrogen product in the storage tank, expanding the liquefied hydrogen product to atmospheric pressure through a second expansion valve;
A hydrogen liquefaction method further comprising a gas-liquid separation step of separating gas and liquid from the product hydrogen expanded through the second expansion valve. In claim 3,
The natural vaporization gas (BOG: Boil Off Gas) generated in the storage tank storing the liquefied product hydrogen in the fourth step and the gaseous hydrogen separated through the gas-liquid separation step pass through the second heat exchanger secondly. A method of liquefying hydrogen, characterized in that it is combined with the second refrigerant hydrogen and recycled as the supply hydrogen gas. In claim 1,
The first pressure range is 18 to 22 bar, the second pressure range is 60 to 70 bar, the first temperature range is a temperature range around the liquefaction temperature of nitrogen, and the second temperature range is -220 to -260 ° C. A hydrogen liquefaction method characterized by: In claim 1,
In the third step, the first refrigerant hydrogen is,
receiving low-temperature energy while first passing through the second heat exchanger;
Through the step of being expanded to a first pressure range through at least one expansion turbine, cooled to a second temperature range, and secondly supplied to the second heat exchanger,
A hydrogen liquefaction method characterized by supplying low-temperature energy to the second refrigerant hydrogen and the product hydrogen through heat exchange while passing through the second heat exchanger in a cooled state. In claim 1,
In the third step, the first refrigerant hydrogen is,
Cooling by first passing through the second heat exchanger and receiving low-temperature energy;
Expanding and cooling through a first expansion turbine and supplying the second heat to the second heat exchanger;
In the second order, low-temperature energy is supplied through the second heat exchanger, and in a re-cooled state, it is expanded and cooled through the second expansion turbine, and is finally cooled to the second temperature range while maintaining the first pressure range, and is then cooled to the second temperature range in the third order. Through the stage of supply to the heat exchanger,
A hydrogen liquefaction method characterized by supplying low-temperature energy to the second refrigerant hydrogen and the product hydrogen through heat exchange while passing through the second heat exchanger in a third stage in a cooled state . In claim 1,
In the second step, the liquid nitrogen is vaporized in the first heat exchanger to supply low-temperature energy for free cooling, and the vaporized nitrogen gas is liquefied again through a nitrogen liquefaction unit to resupply the liquid nitrogen to the first heat exchanger. A hydrogen liquefaction method characterized by having a circulation process. In claim 3,
The first expansion valve performs a flow rate control function when the first refrigerant hydrogen and the second refrigerant hydrogen diverge, and the second expansion valve performs a flow rate control function when the product hydrogen and the refrigerant hydrogen diverge. Hydrogen liquefaction method. In the hydrogen liquefaction device:
Hydrogen gas supply department;
a first compression unit that first compresses the hydrogen gas supplied from the hydrogen gas supply unit to a first pressure range;
a first branch for branching the supplied hydrogen gas into refrigerant hydrogen and product hydrogen;
a second compression unit for secondarily compressing the refrigerant hydrogen to a second pressure range;
a first heat exchanger for pre-cooling the secondarily compressed refrigerant hydrogen and the firstly compressed product hydrogen to a first temperature range;
a second branch unit for branching the refrigerant hydrogen that has passed through the first heat exchange unit into first refrigerant hydrogen and second refrigerant hydrogen;
an expansion unit for expanding the first refrigerant hydrogen to a first pressure range and cooling it to a second temperature range;
a second heat exchanger for supplying low-temperature energy to the product hydrogen to liquefy it through heat exchange between the first refrigerant hydrogen, the second refrigerant hydrogen, and the product hydrogen;
Expanding and further cooling the second refrigerant hydrogen liquefied in the second temperature range while passing through the second heat exchanger firstly to convert it into a gas-liquid mixed state where gas and liquid are mixed, and passing the second heat exchanger secondly. A first expansion valve for;
The first refrigerant hydrogen supplies low-temperature energy as it sequentially passes through the second heat exchange unit and the first heat exchange unit, and is recovered at room temperature in front of the second compression unit to be recycled as the refrigerant hydrogen. and;
a second convergence unit where the second refrigerant hydrogen supplies low-temperature energy as it passes through the second heat exchange unit and the first heat exchange unit, and is recovered at room temperature in front of the first compression unit to be recycled as supplied hydrogen gas;
Equipped with a storage tank to store liquefied product hydrogen,
In the second heat exchange unit,
As the first refrigerant hydrogen passes through the expansion unit, low-temperature energy is supplied to the second refrigerant hydrogen and the product hydrogen through heat exchange,
The second refrigerant hydrogen is liquefied while first passing through the second heat exchanger through heat exchange and vaporized while passing through the second heat exchanger secondarily, and is then converted into the second refrigerant hydrogen first passing through the second heat exchanger. A hydrogen liquefaction device characterized by supplying low-temperature energy and supplying low-temperature energy to the product hydrogen passing through the second heat exchange unit to liquefy it. In claim 10,
A hydrogen liquefaction device comprising an Ortho-Para conversion catalyst for an Ortho-Para conversion reaction of the product hydrogen when passing through the second heat exchanger. In claim 10,
a second expansion valve that expands the liquefied hydrogen product to atmospheric pressure before storing the liquefied hydrogen product in the storage tank;
It further includes a first gas-liquid separator that separates gas and liquid from the product hydrogen expanded through the second expansion valve,
The liquid hydrogen separated through the first gas-liquid separator is stored in the storage tank, and the gaseous hydrogen separated through the first gas-liquid separator joins the second refrigerant hydrogen that passes through the second heat exchanger secondarily. A hydrogen liquefaction device characterized by a. In claim 12,
A hydrogen liquefaction device further comprising a second gas-liquid separator for separating gas-liquid second refrigerant hydrogen in a gas-liquid mixed state that has passed through the first expansion valve. In claim 12,
A hydrogen liquefaction device, characterized in that natural vaporization gas (BOG: Boil Off Gas) generated in a storage tank storing the liquefied product hydrogen joins the second refrigerant hydrogen that passes through the second heat exchanger secondarily. In claim 10,
The expansion part,
A hydrogen liquefaction device comprising a first expansion turbine for expanding and cooling the first refrigerant hydrogen branched through the second branch. In claim 10,
The expansion part,
a first expansion turbine that first expands and cools the first refrigerant hydrogen branched through the second branch to flow into the second heat exchanger;
Characterized by a second expansion turbine for secondly expanding and cooling the supercooled first refrigerant hydrogen while passing through the second heat exchange unit after passing through the first expansion turbine and flowing it back into the second heat exchange unit. Hydrogen liquefaction device. In claim 10,
A hydrogen liquefaction device further comprising a nitrogen liquefaction unit for supplying energy for precooling from the first heat exchange unit, liquefying the vaporized nitrogen gas, and supplying the vaporized nitrogen gas back to the first heat exchange unit. In claim 10,
The first expansion valve performs a flow rate control function when the first refrigerant hydrogen and the second refrigerant hydrogen diverge, and the second expansion valve performs a flow rate control function when the product hydrogen and the refrigerant hydrogen diverge. Hydrogen liquefaction device. In the hydrogen liquefaction method:
The supplied hydrogen gas is first compressed to branch into refrigerant hydrogen and product hydrogen, and the refrigerant hydrogen is secondarily compressed to produce the second compressed refrigerant hydrogen and the first compressed product hydrogen in the first heat exchange unit. Pre-cooling using liquid nitrogen;
The pre-cooled refrigerant hydrogen is branched into first refrigerant hydrogen and second refrigerant hydrogen, and the low-temperature energy generated by expanding the first refrigerant hydrogen is used to store the product hydrogen passing through the second heat exchange unit and the second refrigerant hydrogen. The second refrigerant hydrogen passing through the heat exchange unit is additionally cooled, and the low-temperature energy generated by expanding the additionally cooled second refrigerant hydrogen while first passing through the second heat exchange unit is introduced into the second heat exchange unit to produce the product hydrogen and A hydrogen liquefaction method comprising the step of liquefying the product hydrogen through a circulation cycle method of additionally cooling the second refrigerant hydrogen passing through the second heat exchange unit in the first stage. In claim 19,
The first refrigerant hydrogen is recycled as the refrigerant hydrogen after heat exchange while sequentially passing through the first heat exchange unit, second heat exchange unit, second heat exchange unit, and first heat exchange unit,
The second refrigerant hydrogen is recycled as the supply hydrogen gas after being heat-exchanged while sequentially passing through the first heat exchanger, second heat exchanger, second heat exchanger, and first heat exchanger,
A hydrogen liquefaction method characterized in that natural vaporization gas (BOG: Boil Off Gas) generated in a storage tank storing liquefied product hydrogen is recycled as the supply hydrogen gas together with the second refrigerant hydrogen.

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