Production method of neon and production device of neon

Abstract

To provide a method of producing neon from a raw material mixed gas containing neon, helium, hydrogen, and nitrogen which can reduce a burden exerted an adsorption tower to produce neon efficiently, and to provide a device capable of efficiently producing neon.SOLUTION: A method of producing neon from a raw material mixed gas containing neon, helium, hydrogen, and nitrogen includes: a hydrogen gas conversion step in which the raw material mixed gas and an oxygen containing gas are placed in contact with a catalyst to convert a hydrogen gas into water; a water removal step in which water is removed from the gas obtained through the hydrogen gas conversion step; a first nitrogen rectification separation step in which the gas obtained through the water removal step is rectified to remove nitrogen; an impurity gas adsorption separation step in which the gas obtained through the first nitrogen rectification separation step is placed in contact with an adsorbent to remove nitrogen; and a helium rectification separation step in which the gas obtained through the impurity gas adsorption separation step is rectified to remove a helium gas.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a method for producing neon and an apparatus for producing neon.

Background Art

[0002] Neon is used as an encapsulating gas for discharge such as in fluorescent lamps, or in applications such as for lasers related to semiconductors and liquid crystals.

[0003] Neon is contained in the air at about 18 ppm, and can be produced by separating it from the gas remaining when oxygen, nitrogen, argon, etc. are separated from raw air in a cryogenic air separation unit (ASU) (hereinafter sometimes referred to as the residual gas). When raw air is liquefied and distilled to produce oxygen, nitrogen, argon, etc., helium, neon, hydrogen, etc. with boiling points lower than nitrogen are released from the upper part of the lower rectification column as residual gas that is not condensed. This release is sometimes called helium extraction. Since the residual gas released by helium extraction contains neon, neon can be produced by separating it from the residual gas. The residual gas contains, in addition to neon, helium and hydrogen, but nitrogen also mixes in. When producing neon, it is important how to remove nitrogen before purifying neon.

[0004] As methods for producing neon from residual gas, the techniques of Non-Patent Document 1 and Patent Document 1 are known. Non-Patent Document 1 describes a method in which the residual gas is rectified in a rectification column to reduce the nitrogen concentration to 33%, then hydrogen and oxygen are brought into contact with a catalyst to remove hydrogen, and then low-temperature adsorption is performed twice, followed by final purification to produce neon. Patent Document 1 describes a method for producing neon and helium, which comprises a step of removing most of the nitrogen from the residual gas by a condensation separation operation, a step of removing the remaining nitrogen by a normal-temperature pressure swing adsorption method using synthetic zeolite, and a step of removing hydrogen by a low-temperature pressure swing adsorption method at -100°C or lower using activated carbon to separate neon and helium.

Prior Art Documents

Patent Document

[0005]

Patent Document 1

Non-Patent Document

[0006]

Non-Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0007] In Non-Patent Document 1, when neon is finally purified, liquefied hydrogen is used as a refrigerant. However, the temperature of liquefied hydrogen is -259.2°C to -253°C, and the solidification temperature of nitrogen is -210°C. Therefore, if the gas to be subjected to final purification contains nitrogen, nitrogen will solidify during final purification, blocking pipes and the like. Thus, in Non-Patent Document 1, it is necessary to perform low-temperature adsorption twice in order to remove nitrogen as much as possible before the final purification step. In Patent Document 1, a normal-temperature pressure swing adsorption tower equipped with synthetic zeolite and a low-temperature pressure swing adsorption tower equipped with activated carbon and operated at -100°C or lower are used in combination. When operating such adsorption towers, it is necessary to desorb the gas adsorbed on the adsorbent provided in the adsorption tower from the adsorbent to regenerate the adsorbent. Therefore, in order to perform continuous operation, it is necessary to arrange a plurality of adsorption towers, and while a predetermined gas is adsorbed in one adsorption tower, the predetermined gas adsorbed in the other adsorption tower is desorbed. Further, when the types and amounts of gases adsorbed and removed in the adsorption tower increase, the load on the adsorption tower increases. Therefore, it is necessary to shorten the usage time of the adsorption tower and switch it, repeating adsorption and regeneration. Alternatively, it is necessary to increase the number of adsorption towers or increase the size of the adsorption tower to improve the processing capacity.

[0008] The problems to be solved by the present invention are to provide a method for producing neon from a raw material mixed gas containing neon, helium, hydrogen, and nitrogen, which can reduce the load on the adsorption tower and efficiently produce neon. Another problem to be solved by the present invention is to provide an apparatus capable of efficiently producing neon.

Means for Solving the Problems

[0009] The present invention is as follows. [1] A method for producing neon from a raw material mixed gas containing neon, helium, hydrogen, and nitrogen, comprising a hydrogen gas conversion step of bringing the raw material mixed gas and an oxygen-containing gas into contact with a catalyst to convert hydrogen gas into water, a water removal step of removing water from the gas obtained through the hydrogen gas conversion step, a first nitrogen rectification separation step of rectifying the gas obtained through the water removal step to remove nitrogen, an impurity gas adsorption separation step of bringing the gas obtained through the first nitrogen rectification separation step into contact with an adsorbent to remove impurity gases, and a helium rectification separation step of rectifying the gas obtained through the impurity gas adsorption separation step to remove helium gas. [2] The production method according to [1], including a gas separation step of heat-exchanging the gas obtained through the first nitrogen rectification separation step with a refrigerant at -196°C to -210°C and then performing gas-liquid separation to separate the gas between the first nitrogen rectification separation step and the impurity gas adsorption separation step, and in the impurity gas adsorption separation step, bringing the gas obtained through the gas separation step into contact with an adsorbent. [3] The production method according to [2], wherein in the impurity gas adsorption separation step, impurity gases are removed by temperature swing adsorption at -100°C or lower. [4] The production method according to [1], including a second nitrogen rectification separation step of rectifying the gas obtained through the impurity gas adsorption separation step to remove nitrogen between the impurity gas adsorption separation step and the helium rectification separation step, and in the helium rectification separation step, rectifying the gas obtained through the second nitrogen rectification separation step to remove helium gas. [5] In the impurity gas adsorption and separation step, the manufacturing method described in [4] is used to remove impurity gases by pressure swing adsorption at normal temperature. [6] The raw material mixed gas further contains carbon monoxide, and includes a carbon monoxide conversion step of converting the carbon monoxide contained in the raw material mixed gas into carbon dioxide, and a carbon dioxide removal step of removing carbon dioxide from the gas obtained through the carbon monoxide conversion step. The manufacturing method is as described in any one of [1] to [5]. [7] An apparatus for producing neon from a raw material mixed gas containing neon, helium, hydrogen, and nitrogen, comprising a catalyst tower equipped with a catalyst with which the raw material mixed gas and an oxygen-containing gas come into contact, water removal equipment for removing water contained in the gas from the catalyst tower, a first nitrogen removal rectification tower for rectifying the gas from the water removal equipment to remove nitrogen, a heat exchanger for exchanging heat between the gas from the first nitrogen removal rectification tower and a refrigerant at -196°C to -210°C, a gas-liquid separator for gas-liquid separating the fluid from the heat exchanger, a temperature swing adsorption tower for adsorbing impurity gases contained in the gas from the gas-liquid separator by temperature swing adsorption, and a neon purification rectification tower for rectifying the gas from the temperature swing adsorption tower to remove helium gas and purify neon. [8] An apparatus for producing neon from a raw material mixed gas containing neon, helium, hydrogen, and nitrogen, comprising a catalyst tower equipped with a catalyst with which the raw material mixed gas and an oxygen-containing gas come into contact, water removal equipment for removing water contained in the gas from the catalyst tower, a first nitrogen removal rectification tower for rectifying the gas from the water removal equipment to remove nitrogen, a pressure swing adsorption tower for adsorbing impurity gases contained in the gas from the first nitrogen removal rectification tower by pressure swing adsorption, a second nitrogen removal rectification tower for rectifying the gas from the pressure swing adsorption tower to remove nitrogen, and a neon purification rectification tower for rectifying the gas from the second nitrogen removal rectification tower to remove helium gas and purify neon. [9] The raw material mixed gas further contains carbon monoxide, and includes a second catalyst tower equipped with a catalyst with which the raw material mixed gas comes into contact, and carbon dioxide removal equipment for removing carbon dioxide contained in the gas from the second catalyst tower. The manufacturing apparatus is as described in [7] or [8]. [Advantages of the Invention]

[0010] According to the neon production method of the present invention, when producing neon from a raw material mixed gas containing neon, helium, hydrogen, and nitrogen, the load on the adsorption tower can be reduced, and neon can be efficiently produced. According to the neon production apparatus of the present invention, neon can be efficiently produced.

Brief Description of the Drawings

[0011]

Figure 1

Figure 2

Embodiments for Carrying Out the Invention

[0012] Hereinafter, the present invention will be specifically described based on embodiments. However, the present invention is not limited by the following embodiments, and it is also possible to make modifications within the scope conforming to the above and following gists and implement them, and all of them are included in the technical scope of the present invention.

[0013] The neon production method according to the present invention is a method for producing neon from a raw material mixed gas containing neon, helium, hydrogen, and nitrogen, including a hydrogen gas conversion step of bringing the raw material mixed gas and an oxygen-containing gas into contact with a catalyst to convert hydrogen gas into water, a water removal step of removing water from the gas obtained through the hydrogen gas conversion step, a first nitrogen rectification separation step of rectifying the gas obtained through the water removal step to remove nitrogen, an impurity gas adsorption separation step of bringing the gas obtained through the first nitrogen rectification separation step into contact with an adsorbent to remove impurity gases, and a helium rectification separation step of rectifying the gas obtained through the impurity gas adsorption separation step to remove helium gas.

[0014] According to an embodiment of the method for producing neon according to the present invention, hydrogen gas contained in the raw material mixed gas is converted into water by bringing it into contact with oxygen on a catalyst, and after removing the obtained water, impurity gases are removed in a first nitrogen rectification separation step and an impurity gas adsorption separation step. Thus, before removing nitrogen in the first nitrogen rectification separation step, hydrogen gas contained in the raw material mixed gas is converted into water (hydrogen gas conversion step), and by removing the obtained water (water removal step), oxygen used for the conversion of hydrogen gas into water can be removed together with nitrogen in the first nitrogen rectification separation step. As a result, the gas obtained through the first nitrogen rectification separation step contains almost no hydrogen and oxygen, so the load on the adsorption tower used in the impurity gas adsorption separation step can be reduced. Therefore, the service time of the adsorption tower can be extended, and the production efficiency of neon can be increased. In addition, since it is not necessary to increase the number of adsorption towers or enlarge the adsorption tower to increase the processing capacity, the equipment can be made space-saving and the production cost can be reduced.

[0015] Hereinafter, each step will be described.

[0016] [Hydrogen Gas Conversion Step] In the hydrogen gas conversion step, a raw material mixed gas containing neon, helium, hydrogen, and nitrogen and an oxygen-containing gas are brought into contact with a catalyst to convert hydrogen gas into water. As the catalyst, one that reacts hydrogen with oxygen to produce water is used. As the raw material mixed gas to be brought into contact with the catalyst, for example, when producing oxygen, nitrogen, argon, etc. by liquefying and distilling raw material air, the residual gas discharged from the upper part of the lower rectification column (so-called helium extraction) may be used. As the supply source of oxygen to be brought into contact with the catalyst, an oxygen-containing gas is used. As the oxygen-containing gas, for example, air may be used, or oxygen gas may be used, and it is preferable to use oxygen gas.

[0017] [Water Removal Step] In the water removal step, water is removed from the gas obtained through the hydrogen gas conversion step. The method for removing water contained in the gas is not particularly limited, and examples thereof include a method of removing water using an adsorbent that adsorbs water, a method of removing water by membrane separation, and the like. Among these, a method of removing water using an adsorbent that adsorbs water is preferable.

[0018] The raw material mixed gas may further contain carbon monoxide. When the raw material mixed gas contains carbon monoxide, in the hydrogen gas conversion step, it may also serve as a carbon monoxide conversion step of bringing carbon monoxide and oxygen into contact with a catalyst to convert carbon monoxide into carbon dioxide. In this case, as the catalyst, a catalyst for converting hydrogen gas into water may be used. When the raw material mixed gas contains carbon monoxide, in the water removal step, it may also serve as a carbon dioxide removal step of removing carbon dioxide from the gas obtained through the hydrogen gas conversion step.

[0019] When the raw material mixed gas contains carbon monoxide, as a step separate from the hydrogen gas conversion step, it may include a carbon monoxide conversion step of converting carbon monoxide contained in the raw material mixed gas into carbon dioxide. Also, when the raw material mixed gas contains carbon monoxide, as a step separate from the water removal step, it may include a carbon dioxide removal step of removing carbon dioxide from the gas obtained through the carbon monoxide conversion step. When including the carbon monoxide conversion step and the carbon dioxide removal step, the order with the hydrogen gas conversion step and the water removal step is not particularly limited, and after performing the hydrogen gas conversion step and the water removal step, the carbon monoxide conversion step and the carbon dioxide removal step may be performed, or after performing the hydrogen gas conversion step and the carbon monoxide conversion step in any order, the water removal step and the carbon dioxide removal step may be performed in any order. Further, after performing the conversion of hydrogen to water and the conversion of carbon monoxide to carbon dioxide in the hydrogen gas conversion step, the water removal step and the carbon dioxide removal step may be implemented as separate steps.

[0020] Methods for removing carbon dioxide contained in a gas include, for example, a method using an adsorbent that adsorbs carbon dioxide and a method of removing carbon dioxide by membrane separation. When removing carbon dioxide using an adsorbent, the adsorbent used in the carbon dioxide removal step may be the same as the adsorbent for removing water, or an adsorbent that selectively removes carbon dioxide may be used.

[0021] [First Nitrogen Rectification Separation Step] In the first nitrogen rectification separation step, the gas obtained through the water removal step (or carbon dioxide removal step) is rectified to remove nitrogen. The form of nitrogen removed in the first nitrogen rectification separation step is not particularly limited and may be in a gaseous state or a liquid state, and it is preferably removed in a liquid state. The removed liquefied nitrogen may be used, for example, as a refrigerant.

[0022] [Impurity Gas Adsorption Separation Step] In the impurity gas adsorption separation step, the gas obtained through the first nitrogen rectification separation step is brought into contact with an adsorbent to remove impurity gases. The impurity gases are, for example, nitrogen, oxygen, hydrogen, etc. By removing the impurity gases using an adsorbent, when purifying neon in the helium rectification separation step described later, it is possible to prevent nitrogen contained in the impurity gases from solidifying and blocking pipes, etc.

[0023] [Helium Rectification Separation Step] In the helium rectification separation step, the gas obtained through the impurity gas adsorption separation step is rectified to remove helium gas. By removing the helium gas, neon can be produced. The form of the produced neon is not particularly limited and may be gaseous neon or liquid neon, and it is preferably liquid neon.

[0024] As an embodiment of the method for producing neon according to the present invention, (1) between the first nitrogen rectification separation step and the impurity gas adsorption separation step, the gas obtained through the first nitrogen rectification separation step may be heat-exchanged with a refrigerant at -196°C to -210°C and then gas-liquid separated to separate the gas, or (2) between the impurity gas adsorption separation step and the helium rectification separation step, it may include a second nitrogen rectification separation step of rectifying the gas obtained through the impurity gas adsorption separation step to remove nitrogen. The embodiment including the gas separation step may be hereinafter referred to as Embodiment 1, and the embodiment including the second nitrogen rectification separation step may be hereinafter referred to as Embodiment 2.

[0025] (1) Embodiment 1 In the gas separation step in Embodiment 1, the gas obtained through the first nitrogen rectification separation step is heat-exchanged with a refrigerant at -196°C to -210°C and then gas-liquid separated to separate the gas. By heat-exchanging the gas obtained through the first nitrogen rectification separation step with the refrigerant, the nitrogen contained in the gas obtained through the first nitrogen rectification separation step is liquefied, and by gas-liquid separating the fluid obtained by the heat exchange to remove the liquid, the nitrogen contained in the gas to be gas-liquid separated can be further reduced. As a result, it is not necessary to repeat the low-temperature adsorption twice as in Non-Patent Document 1. The gas obtained through the gas separation step removes the remaining impurity gas by contacting with the adsorbent in the above-described impurity gas adsorption separation step. Thus, by performing the gas separation step between the first nitrogen rectification separation step and the impurity gas adsorption separation step, the load on the adsorption tower used in the impurity gas adsorption separation step can be reduced, so the service time of the adsorption tower can be extended, and the production efficiency of neon can be further increased. The temperature of the refrigerant is not limited as long as it can liquefy the nitrogen contained in the gas obtained through the first nitrogen rectification separation step, but it is preferably as low as possible within the range of -196°C to -210°C, more preferably -200°C to -210°C.

[0026] In the impurity gas adsorption separation step in Embodiment 1, the impurity gas may be removed by temperature swing adsorption. The temperature for removing the impurity gas by temperature swing adsorption may be, for example, a low temperature of -100°C or lower. By removing the impurity gas by temperature swing adsorption at -100°C or lower, the concentration of the impurity gas can be reduced to several ppb, so that high-purity neon can be produced.

[0027] (2) Embodiment 2 In the second nitrogen rectification separation step in Embodiment 2, the gas obtained through the impurity gas adsorption separation step is rectified to remove nitrogen. By performing the second rectification for removing nitrogen, the nitrogen contained in the gas to be fed to the helium rectification separation step can be further reduced. The temperature of the refrigerant used for the rectification performed in the second nitrogen rectification separation step may be equal to or lower than the temperature at which nitrogen liquefies, and more preferably equal to or lower than the temperature at which nitrogen solidifies. The gas obtained through the second nitrogen rectification separation step is rectified in the above-described helium rectification separation step to remove helium gas. As a result, high-purity neon can be produced.

[0028] In the impurity gas adsorption separation step in Embodiment 2, the impurity gas may be removed by pressure swing adsorption. The temperature for removing the impurity gas by pressure swing adsorption may be, for example, normal temperature (20°C ± 15°C). By removing the impurity gas by pressure swing adsorption at normal temperature, the concentration of the impurity gas can be reduced to several ppm. By reducing the concentration of the impurity gas to several ppm, a refrigerant having a temperature equal to or lower than the solidification temperature of nitrogen can be used in the second nitrogen rectification separation step, so that nitrogen can be sufficiently removed and high-purity neon can be produced.

[0029] According to the embodiment of the neon production method according to the present invention, high-purity neon with a purity of 99.999% or higher can be produced.

[0030] Next, an embodiment of the neon production apparatus according to the present invention will be described.

[0031] Embodiment 1 of the neon production apparatus according to the present invention is an apparatus for producing neon from a raw material mixed gas containing neon, helium, hydrogen, and nitrogen, comprising a catalyst tower provided with a catalyst with which the raw material mixed gas and an oxygen-containing gas come into contact, a water removal facility for removing water contained in the gas from the catalyst tower, a first nitrogen removal rectification tower for rectifying the gas from the water removal facility to remove nitrogen, a heat exchanger for exchanging heat between the gas from the first nitrogen removal rectification tower and a refrigerant at -196°C to -210°C, a gas-liquid separator for gas-liquid separating the fluid from the heat exchanger, a temperature swing adsorption tower for adsorbing impurity gases contained in the gas from the gas-liquid separator by the temperature swing adsorption method, and a neon purification rectification tower for rectifying the gas from the temperature swing adsorption tower to remove helium gas and purify neon.

[0032] Embodiment 2 of the neon production apparatus according to the present invention is an apparatus for producing neon from a raw material mixed gas containing neon, helium, hydrogen, and nitrogen, comprising a catalyst tower provided with a catalyst with which the raw material mixed gas and an oxygen-containing gas come into contact, a water removal facility for removing water contained in the gas from the catalyst tower, a first nitrogen removal rectification tower for rectifying the gas from the water removal facility to remove nitrogen, a pressure swing adsorption tower for adsorbing impurity gases contained in the gas from the first nitrogen removal rectification tower by the pressure swing adsorption method, a second nitrogen removal rectification tower for rectifying the gas from the pressure swing adsorption tower to remove nitrogen, and a neon purification rectification tower for rectifying the gas from the second nitrogen removal rectification tower to remove helium gas and purify neon.

[0033] Embodiment 1 and Embodiment 2 of the neon production apparatus are common in that they include a catalyst tower provided with a catalyst with which the raw material mixed gas and an oxygen-containing gas come into contact, a water removal facility for removing water contained in the gas from the catalyst tower, a first nitrogen removal rectification tower for rectifying the gas from the water removal facility to remove nitrogen, an adsorption tower for adsorbing nitrogen, and a neon purification rectification tower for rectifying the gas from the adsorption tower to remove helium gas and purify neon.

[0034] Hereinafter, embodiments of the neon manufacturing apparatus according to the present invention will be specifically described with reference to the drawings. However, the present invention is not limited to the illustrated examples, and it is also possible to make modifications and implement within the scope that can conform to the above and following gists, and all of them are included in the technical scope of the present invention. In each drawing, the same parts are denoted by the same reference numerals to avoid redundant explanations. Also, in each drawing, reference numerals and the like may be omitted, but in such cases, refer to the specification and other drawings.

[0035] (Embodiment 1) FIG. 1 is a schematic diagram showing Embodiment 1 in the neon manufacturing apparatus according to the present invention. As shown in FIG. 1, the neon manufacturing apparatus in Embodiment 1 includes a catalyst tower 1, a water removal facility 2, a first nitrogen removal rectification tower 3, a heat exchanger 4a, a gas-liquid separator 5, temperature swing adsorption towers 6a and 6b, and a neon purification rectification tower 7. The heat exchanger 4a is provided in a container 4.

[0036] The catalyst tower 1 is provided with a catalyst that reacts hydrogen with oxygen to generate water. A raw material mixed gas is supplied to the catalyst tower 1 from a raw material mixed gas supply means 101. As the raw material mixed gas, for example, when producing oxygen, nitrogen, argon, etc. by liquefying and distilling raw material air, the residual gas discharged from the upper part of the lower rectification tower (so-called helium removal) may be used. An oxygen-containing gas is supplied to the catalyst tower 1 from an oxygen-containing gas supply means (not shown). As the oxygen-containing gas, for example, air may be used, or oxygen gas may be used, and it is preferable to use oxygen gas. In the catalyst tower 1, the hydrogen contained in the raw material mixed gas and the oxygen contained in the oxygen-containing gas come into contact with the catalyst, and water is generated. The gas containing the generated water is supplied from the catalyst tower 1 to the water removal facility 2.

[0037] As the water removal equipment 2, for example, an adsorption tower equipped with an adsorbent for adsorbing water, a membrane separation device equipped with a membrane capable of separating water and other gases, etc. can be used. Among these, it is preferable to use an adsorption tower. Also, the adsorption tower and the membrane separation device may be used in combination. In FIG. 1, a configuration example having one water removal equipment is shown, but the number of water removal equipment is not limited to one, and two or more may be used. The gas from which water has been removed by the water removal equipment 2 is supplied from the water removal equipment 2 to the first nitrogen removal rectification tower 3.

[0038] The raw material mixed gas may further contain carbon monoxide. When the raw material mixed gas contains carbon monoxide, in the catalyst tower 1, carbon monoxide and oxygen may be brought into contact with the catalyst to convert carbon monoxide into carbon dioxide. In this case, as the catalyst used in the catalyst tower 1, a catalyst for converting hydrogen gas into water may be used. When the raw material mixed gas contains carbon monoxide, in the water removal equipment 2, carbon dioxide may be removed from the gas obtained through the catalyst tower 1.

[0039] When the raw material mixed gas contains carbon monoxide, the neon production apparatus may include, separately from the catalyst tower 1, a second catalyst tower equipped with a catalyst with which the raw material mixed gas comes into contact. Also, when the raw material mixed gas contains carbon monoxide, the neon production apparatus may include, separately from the water removal equipment 2, a carbon dioxide removal equipment for removing carbon dioxide contained in the gas supplied from the second catalyst tower. When the neon production apparatus includes the second catalyst tower and the carbon dioxide removal equipment, the arrangement order with respect to the catalyst tower 1 and the water removal equipment 2 is not particularly limited, and after arranging the catalyst tower 1 and the water removal equipment 2 in this order, the second catalyst tower and the carbon dioxide removal equipment may be arranged in this order, or after arranging the catalyst tower 1 and the second catalyst tower in an arbitrary order, the water removal equipment 2 and the carbon dioxide removal equipment may be arranged in an arbitrary order. Also, the neon production apparatus may include the catalyst tower 1, not include the second catalyst tower, and include both the water removal equipment 2 and the carbon dioxide removal equipment.

[0040] Examples of carbon dioxide removal equipment include, for example, a carbon dioxide adsorption tower equipped with an adsorbent for adsorbing carbon dioxide, and a membrane separator for removing carbon dioxide by membrane separation. When removing carbon dioxide using an adsorbent, the adsorbent used in the carbon dioxide removal equipment may be an adsorbent for removing water, or an adsorbent for selectively removing carbon dioxide.

[0041] A heat exchanger 111 may be provided between the water removal equipment 2 and the first nitrogen removal rectification tower 3. A refrigerant is supplied to the heat exchanger 111 from a refrigerant supply means 111a, and heat exchange is performed between the refrigerant and the gas supplied from the water removal equipment 2. As the refrigerant, for example, nitrogen gas may be used. As the nitrogen gas, for example, the gas accumulated at the top of a container 31 described later may be used. In this case, a path for discharging helium gas may be connected to the top of the container 31.

[0042] The first nitrogen removal rectification tower 3 is a single rectification tower. The gas introduced into the first nitrogen removal rectification tower 3 is cryogenically liquefied and separated by utilizing the boiling point differences of the respective components. The high-boiling components (nitrogen and oxygen) in the gas are liquefied and accumulate at the bottom, and the low-boiling components (neon and helium) accumulate at the top as gas. The number of theoretical plates provided in the first nitrogen removal rectification tower 3 is not particularly limited, and may be, for example, 8 to 15 plates.

[0043] A reboiler 3a is provided at the bottom of the first nitrogen removal rectification tower 3. A heat medium is supplied to the reboiler 3a from a heat medium supply means 3b, and heat exchange is performed between the heat medium and the liquid liquefied in the first nitrogen removal rectification tower 3. The heat medium after heat exchange is discharged from a path 3c. As the heat medium, for example, nitrogen gas may be used. As the nitrogen gas, for example, the gas accumulated at the top of a container 31 described later may be used. The liquid of the high-boiling components accumulated at the bottom of the first nitrogen removal rectification tower 3 may be discharged out of the system from a path (not shown) provided at the bottom of the first nitrogen removal rectification tower 3. The discharged liquid may be supplied to a container 31 equipped with a condenser 31a described later and used as a refrigerant.

[0044] The first nitrogen removal rectification column 3 is usually provided with a container 31 equipped with a condenser 31a. In FIG. 1, the container 31 is provided above the first nitrogen removal rectification column 3. The gas of the low-boiling component accumulated at the top of the first nitrogen removal rectification column 3 is supplied from the first nitrogen removal rectification column 3 to the condenser 31a provided in the container 31 via the path 3d.

[0045] Refrigerant is supplied to the container 31 from the refrigerant supply means 31d, and heat exchange is performed between the refrigerant and the gas supplied to the condenser 31a. As the refrigerant, for example, the liquid discharged from a path (not shown) provided at the bottom of the first nitrogen removal rectification column 3 may be used. The gas supplied to the condenser 31a undergoes heat exchange with the refrigerant, generating liquid and gas. The generated liquid may be returned from the condenser 31a to the first nitrogen removal rectification column 3 via the path 31c. On the other hand, the generated gas is supplied from the condenser 31a to the heat exchanger 4a provided in the container 4 via the path 31b. Since nitrogen gas accumulates at the top of the container 31, a path for discharging the nitrogen gas to the outside of the system may be connected to the top of the container 31.

[0046] Refrigerant is supplied to the container 4 from the refrigerant supply means 4b, and heat exchange takes place between the refrigerant and the gas supplied to the heat exchanger 4a. As the refrigerant, a fluid with a temperature range of -196°C to -210°C is used. The fluid obtained through heat exchange in the heat exchanger 4a is supplied to the gas-liquid separator 5 and separated into liquid and gas. In this way, the gas obtained after passing through the first nitrogen removal rectification column 3 is heat-exchanged with a refrigerant at -196°C to -210°C in the heat exchanger 4a, and then gas-liquid separated in the gas-liquid separator 5 to remove the liquid and separate the gas, thereby further reducing the nitrogen contained in the gas. The liquid obtained by gas-liquid separation may be discharged outside the system through the path 5b provided at the bottom of the gas-liquid separator 5. The discharged liquid may be used as the refrigerant. Also, the discharged liquid may be returned to the first nitrogen removal rectification column 3. The gas obtained by gas-liquid separation is supplied from the gas-liquid separator 5 to the temperature swing adsorption towers 6a and 6b. The temperature swing adsorption towers 6a and 6b are equipped with an adsorbent for adsorbing impurity gases. The temperature swing adsorption towers 6a and 6b only need to be filled with an adsorbent capable of removing at least nitrogen, and may be further filled with an adsorbent capable of removing hydrogen and water in addition to nitrogen. When the raw material mixed gas contains carbon monoxide, the temperature swing adsorption towers 6a and 6b may be further filled with an adsorbent capable of removing carbon monoxide and carbon dioxide. A valve (not shown) may be arranged on the upstream side of the temperature swing adsorption towers 6a and 6b and configured to be switchable.

[0047] In the temperature swing adsorption towers 6a and 6b, the impurity gases contained in the gas supplied from the gas-liquid separator 5 are adsorbed by the temperature swing adsorption method. The temperature for removing the impurity gases by the temperature swing adsorption method may be, for example, a low temperature of -100°C or lower. By removing the impurity gases by the temperature swing adsorption method at a temperature of -100°C or lower, the concentration of the impurity gases can be reduced to several ppb, so high-purity neon can be produced. Fig. 1 shows a configuration example with two temperature swing adsorption towers, but the number of temperature swing adsorption towers is not limited to two and may be three or more. The gas from which the impurity gases have been removed in the temperature swing adsorption towers 6a and 6b is supplied from the temperature swing adsorption towers 6a and 6b to the neon purification rectification column 7.

[0048] In the neon purification rectification column 7, the gas supplied from the temperature swing adsorption columns 6a and 6b is rectified to remove helium gas and purify neon. The neon purification rectification column 7 is a single rectification column. The gas introduced into the neon purification rectification column 7 is cryogenically liquefied and separated using the boiling point differences of the respective components. The high-boiling component (neon) in the gas is liquefied and accumulates at the bottom, while the low-boiling component (helium) accumulates at the top as a gas. The number of theoretical plates provided in the neon purification rectification column 7 is not particularly limited and may be, for example, 5 to 10 plates.

[0049] The neon purification rectification column 7 is usually provided with a container 71 equipped with a condenser 71a. In FIG. 1, the container 71 is provided above the neon purification rectification column 7. The gas of the low-boiling component accumulated at the top of the neon purification rectification column 7 is helium, and it is supplied from the neon purification rectification column 7 to the condenser 71a provided in the container 71 via the path 7e. A refrigerant is supplied to the container 71 from the refrigerant supply means 71b, and heat exchange occurs between the refrigerant and the gas supplied to the condenser 71a. As the refrigerant, for example, a fluid at -259°C to -253°C may be used, and as the fluid at -259°C to -253°C, liquefied hydrogen may be used. The gas supplied to the condenser 71a undergoes heat exchange with the refrigerant, generating a liquid and a gas. The generated gas is discharged from the condenser 71a to the outside of the system via the path 71d and may be recovered as helium gas 71c. On the other hand, the generated liquid may be returned from the condenser 71a to the neon purification rectification column 7 via the path 71e. In FIG. 1, a configuration example of supplying a refrigerant to the container 71 for heat exchange is shown, but heat exchange may also be performed by cooling the inside of the container 71 to -270°C to -253°C using, for example, a cooling means (not shown).

[0050] A reboiler 7a is provided at the bottom of the neon purification rectification column 7. A heat medium is supplied to the reboiler 7a from the heat medium supply means 7b, and heat exchange occurs between the heat medium and the liquid liquefied inside the neon purification rectification column 7. The heat medium after heat exchange is discharged from the path 7c. As the heat medium, for example, helium gas may be used. As the helium gas, for example, the helium gas 71c recovered from the condenser 71a may be used.

[0051] The liquid of the high-boiling components accumulated at the bottom of the neon purification rectification column 7 is neon, which is discharged out of the system from the path 7d provided at the bottom of the neon purification rectification column 7 and recovered as liquefied neon 201. In FIG. 1, a configuration example of recovering neon in a liquid state is shown, but neon in a gaseous state may also be recovered.

[0052] A heat exchanger 112 may be provided between the temperature swing adsorption towers 6a and 6b and the neon purification rectification column 7. Refrigerant is supplied to the heat exchanger 112 from the refrigerant supply means 112a, and heat exchange is performed between the refrigerant and the gas supplied from the temperature swing adsorption towers 6a and 6b. As the refrigerant, for example, helium gas may be used. As the helium gas, for example, the helium gas 71c recovered from the condenser 71a may be used, or the helium gas accumulated at the top of the container 71 may be used. When the helium gas accumulated at the top of the container 71 is used as the refrigerant, a path for discharging the helium gas may be connected to the top of the container 71.

[0053] (Embodiment 2) FIG. 2 is a schematic diagram showing Embodiment 2 in the neon production apparatus according to the present invention. As shown in FIG. 2, the neon production apparatus in Embodiment 2 includes a catalyst tower 1, a water removal facility 2, a first nitrogen removal rectification column 3, pressure swing adsorption towers 8a and 8b, a second nitrogen removal rectification column 9, and a neon purification rectification column 7.

[0054] In Embodiment 2, the gas of low-boiling components (neon and helium) accumulated at the top of the first nitrogen removal rectification column 3 is supplied from the first nitrogen removal rectification column 3 to the condenser 31a via the path 3d. The gas generated in the condenser 31a is supplied from the condenser 31a to the pressure swing adsorption columns 8a and 8b via the path 31b. The pressure swing adsorption columns 8a and 8b are provided with an adsorbent for adsorbing impurity gases. The pressure swing adsorption columns 8a and 8b only need to be filled with an adsorbent capable of removing at least nitrogen, and may be further filled with an adsorbent capable of removing hydrogen and water in addition to nitrogen. When the raw material mixed gas contains carbon monoxide, the pressure swing adsorption columns 8a and 8b may be further filled with an adsorbent capable of removing carbon monoxide and carbon dioxide. A valve (not shown) may be arranged on the upstream side of the pressure swing adsorption columns 8a and 8b and may be configured to be switchable.

[0055] In the pressure swing adsorption columns 8a and 8b, the impurity gases contained in the gas supplied from the condenser 31a are adsorbed by the pressure swing adsorption method. The temperature at the time of removing the impurity gases by the pressure swing adsorption method may be, for example, normal temperature (20°C ± 15°C). By removing the impurity gases by the pressure swing adsorption method at normal temperature, the concentration of the impurity gases can be reduced to several ppm, so high-purity neon can be produced. Although FIG. 2 shows a configuration example having two pressure swing adsorption columns, the number of pressure swing adsorption columns is not limited to two and may be three or more. The gas from which the impurity gases have been removed in the pressure swing adsorption columns 8a and 8b is supplied from the pressure swing adsorption columns 8a and 8b to the second nitrogen removal rectification column 9.

[0056] The second nitrogen removal rectification column 9 is a single rectification column. The gas introduced into the second nitrogen removal rectification column 9 is cryogenically liquefied and separated by utilizing the boiling point differences of the respective components. The high-boiling components (nitrogen and oxygen) in the gas are liquefied and accumulate at the bottom, while the low-boiling components (neon and helium) accumulate at the top as gas. The number of theoretical plates provided in the second nitrogen removal rectification column 9 is not particularly limited, and for example, it may be 8 to 15 plates. A reboiler 9a is provided at the bottom of the second nitrogen removal rectification column 9. A refrigerant is supplied from a heat medium supply means 9b to the reboiler 9a, and heat exchange occurs between the refrigerant and the liquid liquefied within the second nitrogen removal rectification column 9. The refrigerant after heat exchange is discharged from a path 9c. As the refrigerant, for example, a fluid at -259°C to -253°C may be used, and as the fluid at -259°C to -253°C, liquefied hydrogen may be used. In FIG. 2, a configuration example in which a refrigerant is supplied to the reboiler 9a for heat exchange is shown. However, heat exchange may also be performed by cooling the inside of the container 71 to -270°C to -253°C by, for example, a cooling means (not shown) for the inside of the second nitrogen removal rectification column 9. The liquid of the high-boiling components accumulated at the bottom of the second nitrogen removal rectification column 9 may be discharged outside the system from a path 9e provided at the bottom of the second nitrogen removal rectification column 9 and recovered as the liquid 301. The discharged liquid 301 may be supplied to the container 31 provided with the condenser 31a described above and used as the refrigerant supplied from the refrigerant supply means 31d.

[0057] The second nitrogen removal rectification column 9 is usually provided with a container 91 equipped with a condenser 91a. In FIG. 2, the container 91 is provided above the second nitrogen removal rectification column 9. The gas of the low-boiling component accumulated at the top of the second nitrogen removal rectification column 9 is supplied from the second nitrogen removal rectification column 9 to the condenser 91a provided in the container 91 via the path 9d. A refrigerant is supplied to the container 91 from the refrigerant supply means 91e, and heat exchange is performed between the refrigerant and the gas supplied to the condenser 91a. As the refrigerant, for example, the liquid discharged from a path (not shown) provided at the bottom of the first nitrogen removal rectification column 3 may be used. The gas supplied to the condenser 91a undergoes heat exchange with the refrigerant, generating a liquid and a gas. The generated liquid may be returned from the condenser 91a to the second nitrogen removal rectification column 9 via the path 91c. On the other hand, the generated gas is supplied from the container 91 to the neon purification rectification column 7 via the path 91b.

[0058] A heat exchanger 112 may be provided between the pressure swing adsorption towers 8a, 8b and the second nitrogen removal rectification column 9. A refrigerant is supplied to the heat exchanger 112 from the refrigerant supply means 112a, and heat exchange is performed between the refrigerant and the gas supplied from the pressure swing adsorption towers 8a, 8b. As the refrigerant, for example, helium gas may be used. As the helium gas, for example, the helium gas 71c recovered from the condenser 71a described later may be used, or the helium gas accumulated at the top of the container 71 described later may be used. When the helium gas accumulated at the top of the container 71 is used as the refrigerant, a path for discharging the helium gas may be connected to the top of the container 71.

[0059] In the neon purification rectification column 7, the gas supplied from the second nitrogen removal rectification column 9 is rectified to remove helium gas and purify neon. The neon purification rectification column 7 is a single-stage rectification column. The gas introduced into the neon purification rectification column 7 is cryogenically liquefied and separated using the boiling point difference of each component. The high-boiling component (neon) in the gas is liquefied and accumulates at the bottom, while the low-boiling component (helium) accumulates at the top as a gas. The number of theoretical plates provided in the neon purification rectification column 7 is not particularly limited, and may be, for example, 5 to 10 plates.

[0060] The neon purification rectification column 7 is usually provided with a container 71 equipped with a condenser 71a. In FIG. 2, the container 71 is provided above the neon purification rectification column 7. The gas of the low-boiling component accumulated at the top of the neon purification rectification column 7 is helium, and is supplied from the neon purification rectification column 7 to the condenser 71a provided in the container 71 via the path 7e. Refrigerant is supplied to the container 71 from the refrigerant supply means 71b, and heat exchange is performed between the refrigerant and the gas supplied to the condenser 71a. As the refrigerant, for example, a fluid of -259°C to -253°C may be used, and as the fluid of -259°C to -253°C, liquefied hydrogen may be used. The gas supplied to the condenser 71a undergoes heat exchange with the refrigerant, generating a liquid and a gas. The generated gas is discharged from the condenser 71a to the outside of the system via the path 71d, and may be recovered as helium gas 71c. On the other hand, the generated liquid may be returned from the condenser 71a to the neon purification rectification column 7 via the path 71e. In FIG. 2, a configuration example in which refrigerant is supplied to the container 71 for heat exchange is shown. However, for example, heat exchange may be performed by cooling the inside of the container 71 to -270°C to -253°C by a cooling means (not shown).

[0061] A reboiler 7a is provided at the bottom of the neon purification rectification column 7. Heat medium is supplied to the reboiler 7a from the heat medium supply means 7b, and heat exchange is performed between the heat medium and the liquid liquefied in the neon purification rectification column 7. The heat medium after heat exchange is discharged from the path 7c. As the heat medium, for example, helium gas may be used. As the helium gas, for example, the helium gas 71c recovered from the condenser 71a may be used. The liquid of the high-boiling component accumulated at the bottom of the neon purification rectification column 7 is neon, and is discharged from the path 7d provided at the bottom of the neon purification rectification column 7 to the outside of the system and recovered as liquefied neon 201. In FIG. 2, a configuration example in which liquid-state neon is recovered is shown. However, gaseous neon may be recovered.

[0062] According to Embodiments 1 and 2 of the neon production apparatus according to the present invention, high-purity neon with a purity of 99.999% or more can be produced.

[0063] Thus, by using the apparatus and method disclosed in the present invention, it is possible to reduce the load on the adsorption tower, efficiently produce neon, and reduce the driving energy compared to the prior art. Therefore, it is possible to reduce greenhouse gases and contribute to some activities of the Sustainable Development Goals (SDGs).

Explanation of Signs

[0064] 1 Catalytic tower 2 Water removal facility 3 First nitrogen removal rectification tower 4 Container 4a Heat exchanger 5 Gas-liquid separator 6a, 6b Temperature swing adsorption tower 7 Neon purification rectification tower 8a, 8b Pressure swing adsorption tower 9 Second nitrogen removal rectification tower

Claims

1. A method for producing neon from a raw material mixed gas containing neon, helium, hydrogen, and nitrogen, comprising: a hydrogen gas conversion step of bringing the raw material mixed gas and an oxygen-containing gas into contact with a catalyst to convert hydrogen gas into water; a water removal step of removing water from the gas obtained after the hydrogen gas conversion step; a first nitrogen rectification separation step of rectifying the gas obtained after the water removal step to remove nitrogen; an impurity gas adsorption separation step of bringing the gas obtained after the first nitrogen rectification separation step into contact with an adsorbent to remove impurity gases; a helium rectification separation step of rectifying the gas obtained after the impurity gas adsorption separation step to remove helium gas; A method for producing neon, comprising the above steps.

2. Between the first nitrogen rectification separation step and the impurity gas adsorption separation step, a gas separation step is included, in which the gas obtained after the first nitrogen rectification separation step is heat-exchanged with a refrigerant at -196°C to -210°C and then gas-liquid separated to separate the gas. In the impurity gas adsorption separation step, the gas obtained after the gas separation step is brought into contact with an adsorbent. The production method according to claim 1.

3. In the impurity gas adsorption separation step, the impurity gas is removed by temperature swing adsorption at -100°C or lower. The production method according to claim 2.

4. Between the impurity gas adsorption separation step and the helium rectification separation step, a second nitrogen rectification separation step is included, in which the gas obtained after the impurity gas adsorption separation step is rectified to remove nitrogen. In the helium rectification separation step, the gas obtained after the second nitrogen rectification separation step is rectified to remove helium gas. The production method according to claim 1.

5. In the impurity gas adsorption separation step, the impurity gas is removed by pressure swing adsorption at room temperature. The production method according to claim 4.

6. The raw material mixed gas further contains carbon monoxide, a carbon monoxide conversion step of converting the carbon monoxide contained in the raw material mixed gas into carbon dioxide, a carbon dioxide removal step of removing carbon dioxide from the gas obtained through the carbon monoxide conversion step, The manufacturing method according to claim 1, comprising:

7. An apparatus for producing neon from a raw material mixed gas containing neon, helium, hydrogen, and nitrogen, a catalyst tower provided with a catalyst with which the raw material mixed gas and an oxygen-containing gas come into contact, water removal equipment for removing water contained in the gas from the catalyst tower, a first nitrogen removal rectification tower for rectifying the gas from the water removal equipment to remove nitrogen, a heat exchanger for performing heat exchange between the gas from the first nitrogen removal rectification tower and a refrigerant at -196°C to -210°C, a gas-liquid separator for gas-liquid separating the fluid from the heat exchanger, a temperature swing adsorption tower for adsorbing the impurity gas contained in the gas from the gas-liquid separator by the temperature swing adsorption method, a neon purification rectification tower for rectifying the gas from the temperature swing adsorption tower to remove helium gas and purify neon, An apparatus for producing neon, comprising:

8. An apparatus for producing neon from a raw material mixed gas containing neon, helium, hydrogen, and nitrogen, a catalyst tower provided with a catalyst with which the raw material mixed gas and an oxygen-containing gas come into contact, water removal equipment for removing water contained in the gas from the catalyst tower, a first nitrogen removal rectification tower for rectifying the gas from the water removal equipment to remove nitrogen, a pressure swing adsorption tower for adsorbing the impurity gas contained in the gas from the first nitrogen removal rectification tower by the pressure swing adsorption method, a second nitrogen removal rectification tower for rectifying the gas from the pressure swing adsorption tower to remove nitrogen, A neon purification rectification column that rectifies the gas from the second nitrogen removal rectification column to remove helium gas and purifies neon, A neon production apparatus including

9. The raw material mixed gas further contains carbon monoxide, A second catalyst tower provided with a catalyst with which the raw material mixed gas comes into contact, Carbon dioxide removal equipment for removing carbon dioxide contained in the gas from the second catalyst tower, The production apparatus according to claim 7 or 8, including

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