Cryogenic separation device

Abstract

This cryogenic separation device comprises: a heat exchanger which cools air from an air supply source by subjecting the air to heat exchange with one or both of nitrogen and oxygen that have been separated in a low-pressure fractionating column; a first condenser which condenses first nitrogen gas having been separated in the low-pressure fractionating column via cold energy of hydrogen from a liquid hydrogen supply source; an evaporator which causes liquid oxygen having been separated in the low-pressure fractionating column to evaporate; an air flow pipe through which the air flows and which branches into a first pipe and a second pipe on the upstream side of the heat exchanger; a pressure booster which boosts the pressure of air that flows through the second pipe on the upstream side of the heat exchanger; a second condenser which condenses second nitrogen gas having been separated in a high-pressure fractionating column via cold energy of liquid oxygen in the low-pressure fractionating column and thereby causes the liquid oxygen to evaporate; and an adjuster which adjusts the proportions of flowing air between the first pipe and the second pipe. The first pipe is connected to the low-pressure fractionating column and the second pipe is connected to the high-pressure fractionating column. Liquid nitrogen having been condensed in the first condenser and the second condenser and oxygen gas having been evaporated in the evaporator are supplied to the low-pressure fractionating column.

Description

Cryogenic separation equipment

[0001] The present disclosure relates to a cryogenic separation device.

[0002] Patent Document 1 describes an air separation unit that uses the cold energy of liquid hydrogen. Specifically, the patent discloses a liquid hydrogen fuel supply system that includes a liquid hydrogen storage tank, a vaporizer that vaporizes liquid hydrogen discharged from the liquid hydrogen storage tank, a hydrogen fuel cell that generates electricity by receiving the vaporized hydrogen gas, and a cold energy utilization unit that recovers and utilizes the cold energy through heat exchange during the liquid hydrogen vaporization process. The air separation unit is configured to separate air using the cold energy generated in the liquid hydrogen vaporizer.

[0003] KR102427731B1

[0004] An object of the present disclosure is to provide, as an example, a cryogenic separation device that can reduce the compression power required to send air to a high-pressure rectification column compared to conventional devices and can flexibly respond to changes in the coldness of hydrogen supplied from a liquid hydrogen supply source.

[0005] A cryogenic separation apparatus according to one aspect of the present disclosure is a cryogenic separation apparatus comprising a low-pressure rectification column and a high-pressure rectification column for separating air supplied from an air supply source into nitrogen and oxygen, the cryogenic separation apparatus comprising: a heat exchanger for cooling the air supplied from the air supply source by exchanging heat with one or both of the nitrogen and oxygen separated in the low-pressure rectification column; a first condenser for condensing first nitrogen gas separated in the low-pressure rectification column using the cold heat of hydrogen supplied from a liquid hydrogen supply source; an evaporator for evaporating liquid oxygen separated in the low-pressure rectification column; and a first piping and a second piping through which air supplied from the air supply source flows and which are arranged upstream of the heat exchanger. a booster located upstream of the heat exchanger for pressurizing the air flowing through the second pipe; a second condenser for condensing the second nitrogen gas separated in the high-pressure rectification column by using the cold heat of the liquid oxygen in the low-pressure rectification column and evaporating the liquid oxygen in the low-pressure rectification column; and a regulator for adjusting the ratio of air flowing between the first pipe and the second pipe, wherein the first pipe is connected to the low-pressure rectification column and the second pipe is connected to the high-pressure rectification column, and the liquid nitrogen condensed in the first condenser and the second condenser and the oxygen gas evaporated in the evaporator are supplied to the low-pressure rectification column.

[0006] A cryogenic separation apparatus according to one aspect of the present disclosure has the advantage of being able to reduce the compression power required to send air to a high-pressure rectification column compared to conventional apparatuses, and of being able to flexibly respond to changes in the temperature of hydrogen supplied from a liquid hydrogen supply source.

[0007] Fig. 1 is a diagram illustrating an example of a cryogenic separation apparatus according to an embodiment, and Fig. 2 is a diagram illustrating an example of a heat exchanger and an evaporator in the cryogenic separation apparatus according to an embodiment.

[0008] In a typical cryogenic separation system, a rectification column requires a condenser for nitrogen, a low-boiling component, and an evaporator for oxygen, a high-boiling component. This system is often configured with two rectification columns, a high-pressure column and a low-pressure column, with the condenser for the high-pressure column and the evaporator for the low-pressure column combined into a single heat exchanger. This allows nitrogen gas from the high-pressure column to be condensed with liquid oxygen from the low-pressure column, and then the nitrogen gas from the high-pressure column evaporates the liquid oxygen from the low-pressure column. The majority of the power consumed in this cryogenic separation process is the compression power required to send air to the high-pressure column. In other words, to condense nitrogen gas from the high-pressure column with liquid oxygen from the low-pressure column in the cryogenic separation process, the boiling point of the nitrogen in the high-pressure column must be increased by pressurizing the nitrogen in the high-pressure column so that it exceeds the boiling point of the oxygen in the low-pressure column. Separating air into oxygen and nitrogen in the rectification column also requires cold energy to cryogenically cool the air supplied to the rectification column. For this reason, in cryogenic separation processes, most of the compressed air pressurized by a booster such as a compressor is supplied to the high-pressure rectification column, and part of the compressed air is supplied to the low-pressure rectification column via an expansion turbine. The expansion turbine can generate cold by expanding the compressed air in a manner similar to adiabatic expansion.

[0009] In such a situation, the present inventors have discovered that the compression power required to send air to the fractionator can be reduced by utilizing the cold energy of liquid hydrogen for cryogenic separation.

[0010] As described above, Patent Document 1 discloses an air separation unit that utilizes the cold energy of liquid hydrogen, but does not fully consider how to deal with changes in the cold energy of hydrogen supplied from a liquid hydrogen supply source.

[0011] Therefore, the present inventors conducted extensive research into a cryogenic separation device that can reduce the compression power required to send air to a high-pressure rectification column and can flexibly respond to changes in the temperature of hydrogen supplied from a liquid hydrogen supply source, and as a result, they came up with the above-mentioned aspect of the present disclosure.

[0012] Specific examples of the above-described aspects of the present disclosure will be described below with reference to the accompanying drawings. Each of the specific examples described below is an example of the above-described aspects of the present disclosure. Therefore, unless otherwise stated in the claims, the shapes, numerical values, components, arrangement positions and connection forms of the components shown below do not limit the scope of the claims.

[0013] Furthermore, among the components described below, components that are not described in the independent claims that represent the highest concept of the present disclosure are described as optional components. Furthermore, in the drawings, components with the same reference numerals may not be described in detail. The drawings are schematic illustrations of each component for ease of understanding, and the shapes, dimensional ratios, and the like may not be accurately depicted.

[0014] (Embodiment) Fig. 1 is a diagram showing an example of a cryogenic separation device according to an embodiment. In Fig. 1, gravity acts from "top" to "bottom", and "upper" and "lower" are defined as shown in the figure.

[0015] The cryogenic separation device 100 comprises a heat exchanger 10, a low-pressure rectification column 11A, a high-pressure rectification column 11B, a condenser 12, a condenser 13, an evaporator 14, an air flow piping 20 including a first piping 20A and a second piping 20B, a booster 21, and a regulator 22.

[0016] The low-pressure rectification column 11A and the high-pressure rectification column 11B are devices that separate air supplied from an air supply source into nitrogen and oxygen. In the low-pressure rectification column 11A and the high-pressure rectification column 11B, air cooled to a cryogenic temperature in the heat exchanger 10 is separated into nitrogen and oxygen by utilizing the difference in boiling points of oxygen and nitrogen. Specifically, in each of the low-pressure rectification column 11A and the high-pressure rectification column 11B, a gas-liquid equilibrium state is created by gas-liquid contact between a liquid descending from above and an ascending gas. As a result, the nitrogen component with a low boiling point is contained in a larger amount in the gas phase, and the oxygen component with a high boiling point is contained in a larger amount in the liquid phase. By repeating this process, nitrogen gas with a higher nitrogen concentration is obtained toward the top of each of the low-pressure rectification column 11A and the high-pressure rectification column 11B, and oxygen with a higher oxygen concentration is obtained toward the bottom. Since the rectification processes in the low-pressure rectification column 11A and the high-pressure rectification column 11B are well known, a detailed description thereof will be omitted.

[0017] The air supply source includes a known device for pre-treating the air to be supplied to the cryogenic separation device 100. For example, the air supply source may include an air filter for removing dust, an air compressor, a cooling tower, an adsorber for removing moisture, etc. In the air compressor, the air that has passed through the air filter is pressurized by an amount equivalent to the pressure loss in the air flow pipe 20.

[0018] In the cooling tower, the air pressurized by the air compressor is cooled to an appropriate temperature, and then in the adsorber, moisture and carbon dioxide are removed from the air cooled in the cooling tower.

[0019] However, the above-described configuration of the air supply source is merely an example and is not limited to this example. For example, since the air is merely pressurized by the air compressor by an amount corresponding to the pressure loss in the air distribution pipe 20, the air supply source does not need to be provided with a water cooling system for cooling the air.

[0020] Heat exchanger 10 is a device that cools air supplied from an air supply source by exchanging heat with both the nitrogen and oxygen separated in low-pressure rectification column 11A. Heat exchanger 10 may have any configuration as long as it can cool the air by exchanging heat between the air supplied from the air supply source and the nitrogen and oxygen. However, if the heat exchanger 10 does not have enough cold energy to cool the air, it is necessary to devise a route for the nitrogen gas to flow in order to properly exchange heat between the air and the cryogenic nitrogen gas, for example, as shown in Figure 2 described below.

[0021] In this example, air at a predetermined temperature supplied from an air supply source functions as a heating fluid, and cryogenic nitrogen and oxygen function as heat-receiving fluids in the heat exchanger 10. The predetermined temperature is a value that varies depending on the state of compression of the air.

[0022] Here, the nitrogen that exchanges heat with air in the heat exchanger 10 may be nitrogen gas. For example, as shown in Figure 1, nitrogen gas with a high nitrogen concentration extracted from the top of the low-pressure rectification column 11A can be supplied to the heat exchanger 10. In this case, the nitrogen that has passed through the heat exchanger 10 may be taken out as high-purity nitrogen. If necessary, liquid nitrogen with a high nitrogen concentration extracted from an appropriate location in the cryogenic separation apparatus 100 may be taken out as high-purity nitrogen.

[0023] The oxygen that exchanges heat with air in the heat exchanger 10 may be oxygen gas. For example, as shown in Fig. 1, oxygen gas with a high oxygen concentration extracted from near the liquid surface of the low-pressure rectification column 11A can be supplied to the heat exchanger 10. In this case, the oxygen that has passed through the heat exchanger 10 may be taken out as high-purity oxygen. If necessary, liquid oxygen with a high oxygen concentration extracted from the liquid in the low-pressure rectification column 11A may be taken out as high-purity oxygen.

[0024] In the above description, heat exchanger 10 exchanges heat between air supplied from the air supply source and both the nitrogen and oxygen separated in low-pressure rectification column 11A, but this is not limiting. Heat exchanger 10 may exchange heat between air supplied from the air supply source and either the nitrogen or the oxygen separated in low-pressure rectification column 11A. However, if heat exchanger 10 does not have enough cold energy to cool the air, it is necessary to devise a route for the nitrogen gas to flow in order to properly exchange heat between the air and cryogenic nitrogen gas in heat exchanger 10, for example, as shown in Figure 2 described below.

[0025] The air flow pipe 20 constitutes an air path through which air supplied from an air supply source flows and which branches into a first pipe 20A and a second pipe 20B upstream of the heat exchanger 10. The first pipe 20A passes through the heat exchanger 10 and is then connected to the low-pressure rectification column 11A, and the second pipe 20B passes through the heat exchanger 10 and is then connected to the high-pressure rectification column 11B.

[0026] The pressure booster 21 is a device that boosts the pressure of the air circulating through the second pipe 20B upstream of the heat exchanger 10. The pressure booster 21 may have any configuration as long as it can boost the pressure of the air circulating through the second pipe 20B upstream of the heat exchanger 10. An example of the pressure booster 21 is a compressor. In other words, only the air supplied to the high-pressure rectification column 11B is compressed to a high pressure by the pressure booster 21 provided in the second pipe 20B, while the air supplied to the low-pressure rectification column 11A is only boosted by the amount of pressure loss in the air flow pipe 20. Compared to the pressure of the compressed air by the pressure booster 21, the pressure of the latter air is smaller.

[0027] The regulator 22 is a device for adjusting the proportion of air flowing between the first pipe 20A and the second pipe 20B. The regulator 22 may have any configuration as long as it can adjust the proportion of air flowing between the first pipe 20A and the second pipe 20B. Examples of the regulator 22 include a flow control valve that adjusts the air flow rate by changing the valve opening, a mass flow controller, etc. The flow control valve may be a three-way valve such as an electromagnetic ball valve provided at the branch point of the air flow pipe 20 where the first pipe 20A and the second pipe 20B branch, or a combination of two-way valves such as an electromagnetic or pneumatic butterfly valve provided near the branch point.

[0028] The booster 21 and the regulator 22 may be controlled by a control device. In this case, the control device can control the operation of the booster 21 and the regulator 22 based on detection data from an appropriate detector for detecting the amount of cold energy of the hydrogen supplied from the liquid hydrogen supply source so that the flow rate of air circulating through the second pipe 20B increases as the amount of cold energy of the hydrogen supplied from the liquid hydrogen supply source decreases. The detector may be, for example, a flow meter or a thermometer provided at an appropriate position in the path through which hydrogen flows.

[0029] The control device may control the operation of each device in the cryogenic separation device 100 in addition to the booster 21 and the regulator 22. The control device includes, for example, an arithmetic circuit and a memory circuit that stores a control program. Examples of the arithmetic circuit include an MPU and a CPU. Examples of the memory circuit include a memory. The control device may be composed of a single controller that performs centralized control, or may be composed of multiple controllers that cooperate with each other to perform distributed control.

[0030] It should be noted that the functions of the elements disclosed herein can be performed using circuits or processing circuits, including general-purpose processors, special-purpose processors, integrated circuits, application-specific integrated circuits (ASICs), conventional circuits, or combinations thereof, configured or programmed to perform the disclosed functions. A processor is considered a processing circuit or circuit because it includes transistors and other circuitry. In this specification, a circuit, unit, or means is hardware that performs the recited functions or hardware that is programmed to perform the recited functions. The hardware may be hardware disclosed herein or other known hardware that is programmed or configured to perform the recited functions. Where the hardware is a processor, which is considered a type of circuit, the circuit, unit, or means is a combination of hardware and software, and the software is used to configure the hardware or processor.

[0031] The condenser 12 is a device that condenses the nitrogen gas separated in the low-pressure rectification column 11A using the cold energy of hydrogen supplied from a liquid hydrogen supply source. The "nitrogen gas separated in the low-pressure rectification column 11A" corresponds to the "first nitrogen gas" in the present disclosure. The liquid nitrogen condensed in the condenser 12 is supplied to the low-pressure rectification column 11A. The condenser 12 may have any configuration as long as it can condense the nitrogen gas separated in the low-pressure rectification column 11A using the cold energy of hydrogen.

[0032] In this example, the condenser 12 is provided near the top of the low-pressure rectification column 11 A. This allows the high-concentration nitrogen gas taken out from the top surface of the low-pressure rectification column 11 A to be easily supplied to the condenser 12.

[0033] The liquid hydrogen supply source may include a liquid hydrogen storage tank and a pump for supplying liquid hydrogen in the liquid hydrogen storage tank to the cryogenic separation device 100 .

[0034] However, the above-described configuration of the liquid hydrogen supply source is merely an example and is not limited to this example. For example, when hydrogen recovered from cryogenic heat in the cryogenic separation device 100 is used in a hydrogen gas turbine or the like, it is necessary to pressurize the hydrogen to a high pressure above the critical pressure. Therefore, as in this example, it is better to pressurize the hydrogen to a high pressure using a pump before the cryogenic heat recovery. This reduces the pump power compared to when the hydrogen is pressurized to a high pressure after the cryogenic heat recovery. On the other hand, when the hydrogen recovered from cryogenic heat in the cryogenic separation device 100 is used as a raw material for a chemical reaction, for example, and there is no need to pressurize the hydrogen, the timing of pressurizing the hydrogen using the pump may be either before or after the cryogenic heat recovery.

[0035] The hydrogen that has passed through the condenser 12 is supplied to an appropriate hydrogen utilization facility. Examples of such hydrogen utilization facilities include, but are not limited to, a hydrogen gas turbine.

[0036] The evaporator 14 is a device that evaporates the liquid oxygen separated in the low-pressure rectification column 11A. The oxygen gas evaporated in the evaporator 14 is supplied to the low-pressure rectification column 11A. The evaporator 14 may have any configuration as long as it can evaporate the liquid oxygen separated in the low-pressure rectification column 11A.

[0037] In this example, the evaporator 14 is provided near the bottom of the low-pressure rectification column 11A, and liquid oxygen taken out from the side of the region in which liquid oxygen accumulates in the low-pressure rectification column 11A is supplied to the evaporator 14, and the evaporator 14 recovers heat from an appropriate heat medium, thereby evaporating the liquid oxygen in the evaporator 14. Specific examples of such heat medium will be described later.

[0038] The condenser 13 is a device that condenses the nitrogen gas separated in the high-pressure rectification column 11B using the cold energy of the liquid oxygen in the low-pressure rectification column 11A, and evaporates the liquid oxygen in the low-pressure rectification column 11A. The "nitrogen gas separated in the high-pressure rectification column 11B" corresponds to the "second nitrogen gas" in this disclosure. The condenser 13 may have any configuration as long as it can condense the nitrogen gas separated in the high-pressure rectification column 11B using the cold energy of the liquid oxygen in the low-pressure rectification column 11A, and evaporate the liquid oxygen in the low-pressure rectification column 11A.

[0039] In this example, the condenser 13 comprises a heat exchanger disposed in the liquid oxygen in the low-pressure rectification column 11A. In this heat exchanger, the nitrogen gas separated in the high-pressure rectification column 11B functions as a heating fluid, and the liquid oxygen in the low-pressure rectification column 11A functions as a heat-receiving fluid. As a result, the liquid oxygen in the low-pressure rectification column 11A recovers heat from the nitrogen gas separated in the high-pressure rectification column 11B, causing the latter nitrogen gas to condense and the former liquid oxygen to evaporate.

[0040] The liquid nitrogen condensed in the condenser 13 is supplied to the low-pressure rectification column 11A and also to the high-pressure rectification column 11B. In addition, oxygen-rich liquid air is taken out from the bottom of the high-pressure rectification column 11B and supplied to the low-pressure rectification column 11A.

[0041] As described above, the cryogenic separation apparatus 100 of this embodiment can reduce the compression power required to send air to the high-pressure rectification column 11B compared to conventional apparatuses, and can flexibly respond to changes in the temperature of hydrogen supplied from a liquid hydrogen supply source.

[0042] Specifically, in the cryogenic separation apparatus 100 of this embodiment, the regulator 22 adjusts the flow rate of the air circulating through the second pipe 20B so that the smaller the amount of cryogenic heat of the hydrogen supplied from the liquid hydrogen supply source, the larger the flow rate of the air. In other words, the regulator 22 appropriately adjusts the amount of air allocated to the low-pressure rectification column 11A and the high-pressure rectification column 11B in accordance with the amount of hydrogen supplied from the liquid hydrogen supply source. As a result, in the cryogenic separation apparatus 100 of this embodiment, only the air supplied to the high-pressure rectification column 11B is compressed by the booster 21, and therefore, compared to conventional systems, the cryogenic separation apparatus 100 can flexibly respond to changes in the amount of cryogenic heat of the hydrogen supplied from the liquid hydrogen supply source while reducing the compression power for sending air to the high-pressure rectification column 11B.

[0043] Furthermore, if the amount of cold energy from hydrogen is insufficient for the desired separation amounts of oxygen and nitrogen required in the cryogenic separation apparatus 100, the amount of condensed nitrogen gas separated in the low-pressure rectification column 11A may be insufficient. Therefore, the cryogenic separation apparatus 100 of this embodiment is provided with condensers 12 and 13 as condensers for condensing the nitrogen gas separated in the low-pressure rectification column 11A, thereby reducing the possibility of an insufficient amount of condensed nitrogen gas.

[0044] Furthermore, if the amount of cryogenic energy of hydrogen is insufficient for the desired separation amounts of oxygen and nitrogen required in the cryogenic separation apparatus 100, the purity of oxygen separated in the low-pressure rectification column 11A may fall below the desired value. Therefore, the cryogenic separation apparatus 100 of this embodiment is provided with a condenser 13 and an evaporator 14 as evaporators for re-evaporating the liquid oxygen separated in the low-pressure rectification column 11A, thereby reducing the possibility that the oxygen purity will fall below the desired value.

[0045] Furthermore, the cryogenic separation device 100 of this embodiment can eliminate the need for a conventional expansion turbine by using the cryogenic heat of hydrogen to provide the cryogenic heat required for cryogenic separation.

[0046] <Specific example of heat exchanger and evaporator> Figure 2 is a diagram showing an example of a heat exchanger and evaporator in a cryogenic separation device of an embodiment. In Figure 2, gravity acts from "top" to "bottom", and "upper" and "lower" are taken as shown in the figure.

[0047] The cryogenic separation apparatus 100 comprises a heat exchanger 10A, a heat exchanger 10B, a low-pressure rectification column 11A, a high-pressure rectification column 11B, a condenser 12, a condenser 13, an evaporator 14, an air circulation pipe 20 including a first pipe 20A and a second pipe 20B, a booster 21, and a regulator 22. Here, the low-pressure rectification column 11A, the high-pressure rectification column 11B, the condensers 12, 13, the air circulation pipe 20, the booster 21, and the regulator 22 are the same as those described above, and therefore description thereof will be omitted. The heat exchanger 10 in Figure 1 comprises a heat exchanger 10A and a heat exchanger 10B.

[0048] Heat exchanger 10A is a device that cools air supplied from an air supply source by exchanging heat with nitrogen gas separated in low-pressure rectification column 11A. That is, in heat exchanger 10A, air supplied from the air supply source functions as a heating fluid, and cryogenic nitrogen gas functions as a heat-receiving fluid.

[0049] Here, the nitrogen gas that exchanges heat with air in the heat exchanger 10A is extracted from the top surface of the low-pressure rectification column 11A and supplied to the heat exchanger 10A.

[0050] In heat exchanger 10A, heat exchange may be carried out between air supplied from an air supply source and oxygen separated in low-pressure rectification column 11A, as in heat exchanger 10 of Fig. 1. In this case, the oxygen that exchanges heat with air in heat exchanger 10A is the same as described above, and therefore a detailed description thereof will be omitted.

[0051] Heat exchanger 10B is a device that cools nitrogen gas that has passed through heat exchanger 10A by exchanging heat with hydrogen that has passed through condenser 12. In other words, the extremely low-temperature nitrogen gas that has passed through heat exchanger 10A functions as a heating fluid, and the extremely low-temperature hydrogen that has passed through condenser 12 functions as a heat-receiving fluid.

[0052] The evaporator 14 is a device that evaporates the liquid oxygen separated in the low-pressure rectification column 11A by recovering heat from the nitrogen gas separated in the low-pressure rectification column 11A. Specifically, the evaporator 14 exchanges heat between the nitrogen gas that has passed through the heat exchanger 10A and the liquid oxygen.

[0053] The evaporator 14 includes an evaporation tank 14A that stores liquid oxygen and a heat exchanger 14B disposed in the liquid oxygen in the evaporation tank 14A. In the heat exchanger 14B, the nitrogen gas that has passed through the heat exchanger 10A functions as a heating fluid, and the liquid oxygen in the evaporation tank 14A functions as a heat-receiving fluid. At this time, the temperature of the nitrogen gas immediately before flowing into the heat exchanger 14B is adjusted to a value slightly higher than the boiling point of the liquid oxygen in the evaporation tank 14A. The liquid oxygen in the evaporation tank 14A then evaporates by recovering heat from the nitrogen gas, and the nitrogen gas imparts heat of evaporation to the liquid oxygen, thereby cooling the nitrogen gas.

[0054] In this example, a nitrogen circulation path 30 is formed to circulate nitrogen gas between the heat exchangers 10A and 10B by returning the nitrogen gas that has passed through the heat exchanger 10B to the heat exchanger 10A. In addition, a nitrogen branch path 31 is formed to guide a portion of the nitrogen gas flowing in the heat exchanger 10A to the evaporator 14, and the nitrogen branch path 31 that has passed through the evaporator 14 merges with the nitrogen circulation path 30 in the heat exchanger 10B.

[0055] In this way, in the cryogenic separation apparatus 100 of this embodiment, the heat exchanger 10B directly uses the cold energy of hydrogen to cool the nitrogen gas circulating through the nitrogen circulation path 30, and the heat exchanger 10A indirectly uses the cold energy of hydrogen to exchange heat between the nitrogen gas circulating through the nitrogen circulation path 30 and the air supplied from the air supply source, thereby cooling the air. Furthermore, a portion of the nitrogen gas circulating through the nitrogen circulation path 30 can be used as a heat source for evaporating liquid oxygen in the evaporator 14. In other words, the cryogenic separation apparatus 100 of this embodiment can use the sensible heat of hydrogen and the heat of evaporation of liquid oxygen as the cold energy for cooling the air supplied to the low-pressure rectification column 11A and the high-pressure rectification column 11B to a liquefaction temperature.

[0056] The reason why heat exchange between nitrogen gas and hydrogen is performed in the heat exchanger 10B and heat exchange between nitrogen gas and air is performed in the heat exchanger 10A is as follows.

[0057] If heat is exchanged between air and hydrogen in a heat exchanger, the flow path members of the heat exchanger must be properly maintained to prevent hydrogen from leaking into the air from welds, joints, etc. of the flow path members.

[0058] However, the cryogenic separation device 100 of this embodiment exchanges heat between nitrogen gas and hydrogen in heat exchanger 10B and between nitrogen gas and air in heat exchanger 10A, thereby reducing the maintenance burden on the flow path components that make up heat exchanger 10A and heat exchanger 10B compared to when hydrogen and air are exchanged in a heat exchanger.

[0059] The reason why the nitrogen gas circulating through the nitrogen circulation path 30 is supplied to the evaporator 14 is as follows.

[0060] If hydrogen at an appropriate temperature is to be supplied to the evaporator, it is necessary to properly maintain the flow path members in the evaporator so that hydrogen does not leak into the liquid oxygen from welds, joints, etc. of the flow path members.

[0061] However, the cryogenic separation device 100 of this embodiment supplies nitrogen gas circulating through the nitrogen circulation path 30 to the evaporator 14 via the nitrogen branch path 31, thereby reducing the maintenance burden on the flow path components that make up the evaporator 14 compared to when hydrogen is supplied to the evaporator.

[0062] From the above description, many modifications and other embodiments of the present disclosure will be apparent to those skilled in the art. Therefore, the above description should be construed as illustrative only and is provided for the purpose of teaching those skilled in the art how to carry out the present disclosure. Substantial changes can be made in the structure and function of the present disclosure without departing from the spirit of the present disclosure.

[0063] (Regarding Each Aspect of the Present Disclosure) From the above description, the following each aspect of the present disclosure can be devised.

[0064] A first aspect of the present disclosure is a cryogenic separation apparatus including a low-pressure rectification column and a high-pressure rectification column that separate air supplied from an air supply source into nitrogen and oxygen, the cryogenic separation apparatus including: a heat exchanger that cools the air supplied from the air supply source by exchanging heat with one or both of the nitrogen and oxygen separated in the low-pressure rectification column; a first condenser that condenses the first nitrogen gas separated in the low-pressure rectification column using the cold heat of hydrogen supplied from a liquid hydrogen supply source; an evaporator that evaporates the liquid oxygen separated in the low-pressure rectification column; and a first piping and a second piping through which the air supplied from the air supply source flows and which are arranged upstream of the heat exchanger. the first piping is connected to the low-pressure rectification column, and the second piping is connected to the high-pressure rectification column, and the liquid nitrogen condensed in the first condenser and the second condenser is connected to the high-pressure rectification column. The liquid nitrogen condensed in the first condenser and the second condenser, and the oxygen gas evaporated in the evaporator are supplied to the low-pressure rectification column.

[0065] With this configuration, the cryogenic separation apparatus of this embodiment can reduce the compression power required to send air to the high-pressure rectification column compared to conventional apparatuses, and can flexibly respond to changes in the coldness of the hydrogen supplied from the liquid hydrogen supply source.

[0066] Specifically, in the cryogenic separation apparatus of this embodiment, the regulator adjusts the flow rate of the air circulating through the second pipe so that the smaller the cryogenic energy of the hydrogen supplied from the liquid hydrogen supply source, the larger the flow rate of the air circulating through the second pipe. In other words, the regulator appropriately adjusts the amount of air allocated to the low-pressure rectification column and the high-pressure rectification column in accordance with the amount of hydrogen supplied from the liquid hydrogen supply source. As a result, in the cryogenic separation apparatus of this aspect, only the air supplied to the high-pressure rectification column is compressed by the booster, and therefore, compared to conventional apparatuses, the cryogenic separation apparatus can flexibly respond to changes in the cryogenic energy of the hydrogen supplied from the liquid hydrogen supply source while reducing the compression power required to send air to the high-pressure rectification column.

[0067] Furthermore, if the amount of cold energy of hydrogen is insufficient for the desired separation amounts of oxygen and nitrogen required in the cryogenic separation apparatus, the amount of condensation of the first nitrogen gas separated in the low-pressure rectification column may be insufficient. Therefore, the cryogenic separation apparatus of this embodiment is provided with a first condenser and a second condenser as condensers for condensing the first nitrogen gas separated in the low-pressure rectification column, thereby reducing the possibility of an insufficient amount of condensation of the first nitrogen gas.

[0068] Furthermore, if the amount of cryogenic energy of hydrogen is insufficient for the desired separation amounts of oxygen and nitrogen required in the cryogenic separation apparatus, the purity of oxygen separated in the low-pressure rectification column may fall below the desired value. Therefore, the cryogenic separation apparatus of this embodiment is provided with a second condenser and an evaporator as evaporators for re-evaporating the liquid oxygen separated in the low-pressure rectification column, thereby reducing the possibility that the oxygen purity will fall below the desired value.

[0069] Furthermore, the cryogenic separation device of this embodiment can eliminate the need for a conventional expansion turbine by using the cryogenic heat of hydrogen to provide the cryogenic heat required for cryogenic separation.

[0070] Here, a second aspect of the present disclosure relates to the cryogenic separation apparatus of the first aspect, wherein the evaporator evaporates the liquid oxygen separated in the low-pressure rectification column by recovering heat from the first nitrogen gas. Furthermore, a third aspect of the present disclosure relates to the cryogenic separation apparatus of the second aspect, wherein the heat exchanger cools air supplied from an air supply source by heat exchange with the first nitrogen gas separated in the low-pressure rectification column, and a second heat exchanger cools the first nitrogen gas by heat exchange with hydrogen that has passed through the first condenser. Furthermore, a fourth aspect of the present disclosure relates to the cryogenic separation apparatus of the second or third aspect, wherein the evaporator exchanges heat between the first nitrogen gas that has passed through the first heat exchanger and the liquid oxygen, and the second heat exchanger exchanges heat between the first nitrogen gas that has passed through the evaporator and hydrogen that has passed through the first condenser.

[0071] According to the above configuration, in the cryogenic separation apparatus of this embodiment, the second heat exchanger directly uses the cold energy of hydrogen to cool the first nitrogen gas that has passed through the first heat exchanger, and the first heat exchanger indirectly uses the cold energy of hydrogen to exchange heat between the first nitrogen gas separated in the low-pressure rectification column and air supplied from the air supply source, thereby cooling the air. Furthermore, the first nitrogen gas that has passed through the first heat exchanger can be used as a heat source for evaporating liquid oxygen in the evaporator. In other words, the cryogenic separation apparatus of this embodiment can use the sensible heat of hydrogen and the heat of evaporation of liquid oxygen as cold energy for cooling the air supplied to the low-pressure rectification column and the high-pressure rectification column to a liquefaction temperature.

[0072] The reason why the first nitrogen gas is heat exchanged with hydrogen in the second heat exchanger and the first nitrogen gas is heat exchanged with air in the first heat exchanger is as follows.

[0073] If heat is exchanged between air and hydrogen in a heat exchanger, the flow path members of the heat exchanger must be properly maintained to prevent hydrogen from leaking into the air from welds, joints, etc. of the flow path members.

[0074] However, in the cryogenic separation device of this embodiment, by exchanging heat between the first nitrogen gas and hydrogen in the second heat exchanger and between the first nitrogen gas and air in the first heat exchanger, the maintenance burden on the flow path components that make up the first heat exchanger and the second heat exchanger can be reduced compared to when heat is exchanged between hydrogen and air in a heat exchanger.

[0075] The reason why the first nitrogen gas that has passed through the first heat exchanger is supplied to the evaporator is as follows.

[0076] If hydrogen at an appropriate temperature is to be supplied to the evaporator, it is necessary to properly maintain the flow path members in the evaporator so that hydrogen does not leak into the liquid oxygen from welds, joints, etc. of the flow path members.

[0077] However, the cryogenic separation device of this embodiment can reduce the maintenance burden on the flow path components that make up the evaporator by supplying the first nitrogen gas that has passed through the first heat exchanger to the evaporator, compared to when hydrogen is supplied to the evaporator.

[0078] 10: Heat exchanger 10A: Heat exchanger 10B: Heat exchanger 11A: Low-pressure rectification column 11B: High-pressure rectification column 12: Condenser 13: Condenser 14: Evaporator 14A: Evaporation tank 14B: Heat exchanger 20: Air circulation piping 20A: First piping 20B: Second piping 21: Pressure booster 22: Regulator 30: Nitrogen circulation path 31: Nitrogen branch path 100: Cryogenic separation device

Claims

1. A cryogenic separation apparatus comprising a low-pressure rectification column and a high-pressure rectification column for separating air supplied from an air supply source into nitrogen and oxygen, comprising: a heat exchanger for cooling the air supplied from the air supply source by exchanging heat with one or both of the nitrogen and oxygen separated in the low-pressure rectification column; a first condenser for condensing the first nitrogen gas separated in the low-pressure rectification column using the cold heat of hydrogen supplied from a liquid hydrogen supply source; an evaporator for evaporating the liquid oxygen separated in the low-pressure rectification column; an air distribution pipe through which the air supplied from the air supply source flows and which branches into a first pipe and a second pipe upstream of the heat exchanger; a pressure booster for pressurizing the air flowing in the second pipe upstream of the heat exchanger; and a second condenser for condensing the second nitrogen gas separated in the high-pressure rectification column using the cold heat of the liquid oxygen in the low-pressure rectification column and evaporating the liquid oxygen in the low-pressure rectification column. a regulator that adjusts the ratio of air circulating between the first pipe and the second pipe, wherein the first pipe is connected to the low-pressure rectification column, and the second pipe is connected to the high-pressure rectification column, and the liquid nitrogen condensed in the first condenser and the second condenser, and the oxygen gas evaporated in the evaporator are supplied to the low-pressure rectification column.

2. A cryogenic separation apparatus according to claim 1, wherein the evaporator evaporates the liquid oxygen separated in the low-pressure rectification column by recovering heat from the first nitrogen gas.

3. The cryogenic separation apparatus according to claim 2, wherein the heat exchanger comprises a first heat exchanger that cools the air supplied from the air supply source by exchanging heat with the first nitrogen gas separated in the low-pressure rectification column, and a second heat exchanger that cools the first nitrogen gas that has passed through the first heat exchanger by exchanging heat with hydrogen that has passed through the first condenser.

4. A cryogenic separation device as described in claim 2 or 3, wherein the evaporator exchanges heat between the first nitrogen gas that has passed through the first heat exchanger and the liquid oxygen, and the second heat exchanger exchanges heat between the first nitrogen gas that has passed through the evaporator and the hydrogen that has passed through the first condenser.

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