Method for producing neon and apparatus for producing neon

Abstract

Provided is a method with which it is possible to efficiently produce neon by reducing a load applied to an adsorption tower when producing neon from a raw-material mixed gas containing neon, helium, hydrogen, and nitrogen. Also provided is an apparatus with which it is possible to efficiently produce neon.　This method for producing neon from a raw-material mixed gas containing neon, helium, hydrogen, and nitrogen includes a hydrogen gas conversion step for bringing the raw-material mixed gas and an oxygen-containing gas into contact with a catalyst to convert hydrogen gas to water, a water removal step for removing water from the gas obtained through the hydrogen gas conversion step, a first nitrogen rectification and separation step for rectifying the gas obtained through the water removal step to remove nitrogen, an impurity gas adsorption and separation step for bringing the gas obtained through the first nitrogen rectification and separation step into contact with an adsorbent to remove nitrogen, and a helium rectification and separation step for rectifying the gas obtained through the impurity gas adsorption and separation step to remove helium gas.

Description

Neon manufacturing method and neon manufacturing device

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

[0002] Neon is used as a discharge gas in fluorescent lamps and in lasers related to semiconductors and liquid crystal displays.

[0003] Neon is contained in air at approximately 18 ppm and can be produced by separating it from the gas (hereinafter sometimes referred to as residual gas) remaining when oxygen, nitrogen, argon, etc. are separated from feed air in a cryogenic air separation unit (ASU). When oxygen, nitrogen, argon, etc. are produced by liquefying and distilling feed air, helium, neon, hydrogen, etc., which have lower boiling points than nitrogen, are released from the top of the lower rectification column as uncondensed residual gas. This release is sometimes called helium withdrawal. Since the residual gas released by helium withdrawal contains neon, neon can be produced by separating it from the residual gas. The residual gas contains helium and hydrogen in addition to neon, but nitrogen is also mixed in. When producing neon, it is important to remove nitrogen before refining the neon.

[0004] Known methods for producing neon from residual gas include those described in Non-Patent Document 1 and Patent Document 1. 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%, hydrogen and oxygen are brought into contact with a catalyst to remove hydrogen, and then low-temperature adsorption is performed twice before final purification to produce neon. Patent Document 1 describes a method for producing neon and helium, which includes 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 ambient temperature pressure swing adsorption using synthetic zeolite, and a step of removing hydrogen by low-temperature pressure swing adsorption at −100° C. or below using activated carbon to separate neon and helium.

[0005] Patent No. 3268177

[0006] W. H. Isalski, "Separation of Gases" (Monographs on cryogenics.5), Clarendon Press, 1989, p. 100-101

[0007] In Non-Patent Document 1, liquefied hydrogen is used as a refrigerant in the final purification of neon. However, since the temperature of liquefied hydrogen is −259.2°C to −253°C and the solidification temperature of nitrogen is −210°C, if nitrogen is contained in the gas subjected to the final purification, the nitrogen will solidify during the final purification and clog piping, etc. Therefore, in Non-Patent Document 1, low-temperature adsorption must be performed twice to remove as much nitrogen as possible before the final purification step. In Patent Document 1, a room-temperature pressure swing adsorption tower equipped with synthetic zeolite and a low-temperature pressure swing adsorption tower equipped with activated carbon operated at −100°C or below are used in combination. When operating such an adsorption tower, it is necessary to desorb the gas adsorbed on the adsorbent installed in the adsorption tower from the adsorbent to regenerate the adsorbent. Therefore, for continuous operation, multiple adsorption towers are required, and a specific gas is adsorbed in one adsorption tower while the adsorbed specific gas is desorbed in the other adsorption tower. Furthermore, as the types and amounts of gases to be adsorbed and removed by the adsorption towers increase, the load on the adsorption towers increases, making it necessary to shorten the usage time of the adsorption towers and switch between them, repeating adsorption and regeneration, or increasing the number of adsorption towers or making the adsorption towers larger to increase processing capacity.

[0008] The present invention aims to provide a method for efficiently producing neon from a raw material gas mixture containing neon, helium, hydrogen, and nitrogen, while reducing the load on an adsorption tower. Another aim of the present invention is to provide an apparatus for efficiently producing neon.

[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, the method comprising: a hydrogen gas conversion step in which the raw material mixed gas and an oxygen-containing gas are contacted with a catalyst to convert 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 nitrogen is rectified from the gas obtained through the water removal step; an impurity gas adsorption separation step in which impurity gas is removed by contacting the gas obtained through the first nitrogen rectification separation step with an adsorbent; and a helium rectification separation step in which helium gas is rectified from the gas obtained through the impurity gas adsorption separation step. [2] The method according to [1] further comprises, between the first nitrogen rectification separation step and the impurity gas adsorption separation step, a gas separation step in which the gas obtained through the first nitrogen rectification separation step is heat-exchanged with a refrigerant at −196° C. to −210° C., followed by gas-liquid separation to separate the gas, wherein the impurity gas adsorption separation step contacts the gas obtained through the gas separation step with an adsorbent. [3] The manufacturing method according to [2], in which the impurity gas adsorption / separation step involves removing impurity gases by temperature swing adsorption at -100°C or lower. [4] The manufacturing method according to [1], in which a second nitrogen rectification / separation step is included between the impurity gas adsorption / separation step and the helium rectification / separation step, in which nitrogen is removed by rectifying the gas obtained through the impurity gas adsorption / separation step, and in which helium gas is removed by rectifying the gas obtained through the second nitrogen rectification / separation step. [5] The manufacturing method according to [4], in which the impurity gas adsorption / separation step involves removing impurity gases by pressure swing adsorption at room temperature. [6] The manufacturing method according to any one of [1] to [5], in which the raw material mixed gas further contains carbon monoxide, and in which a carbon monoxide conversion step is included in which the carbon monoxide contained in the raw material mixed gas is converted into carbon dioxide. [7] The manufacturing method according to any one of [1] to [5], in which the raw material mixed gas further contains carbon monoxide, and in which a carbon monoxide conversion step is included in which the carbon monoxide contained in the raw material mixed gas is converted into carbon dioxide, and a carbon dioxide removal step is included in which carbon dioxide is removed from the gas obtained through the carbon monoxide conversion step.[8] An apparatus for producing neon from a raw material mixed gas containing neon, helium, hydrogen, and nitrogen, the apparatus comprising: a catalytic tower equipped with a catalyst with which the raw material mixed gas comes into contact with an oxygen-containing gas; water removal equipment for removing water contained in the gas from the catalytic 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 separating the fluid from the heat exchanger into gas and liquid; 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. [9] An apparatus for producing neon from a raw material mixed gas containing neon, helium, hydrogen, and nitrogen, the apparatus comprising: a catalyst tower equipped with a catalyst with which the raw material mixed gas comes into contact with an oxygen-containing gas, a water removal system for removing water contained in the gas from the catalyst tower, a first nitrogen removal rectification tower that rectifies the gas from the water removal system to remove nitrogen, a pressure swing adsorption tower that adsorbs impurity gases contained in the gas from the first nitrogen removal rectification tower by pressure swing adsorption, a second nitrogen removal rectification tower that rectifies the gas from the pressure swing adsorption tower to remove nitrogen, and a neon purification rectification tower that rectifies the gas from the second nitrogen removal rectification tower to remove helium gas and purify neon.

[10] The apparatus for producing neon according to [8] or [9], wherein the raw material mixed gas further contains carbon monoxide, and the apparatus comprises a second catalyst tower equipped with a catalyst with which the raw material mixed gas comes into contact.

[11] The manufacturing apparatus according to [8] or [9], wherein the raw material mixed gas further contains carbon monoxide, and further includes: a second catalytic tower equipped with a catalyst with which the raw material mixed gas comes into contact; and carbon dioxide removal equipment that removes carbon dioxide contained in the gas from the second catalytic tower.

[0010] According to the neon production method of the present invention, neon can be produced efficiently from a raw material mixed gas containing neon, helium, hydrogen, and nitrogen while reducing the load on the adsorption tower. The neon production apparatus of the present invention allows for efficient neon production.

[0011] Fig. 1 is a schematic diagram showing a neon manufacturing apparatus according to a first embodiment of the present invention, and Fig. 2 is a schematic diagram showing a neon manufacturing apparatus according to a second embodiment of the present invention.

[0012] The present invention will be specifically described below based on the embodiments, but the present invention is not limited to the following embodiments, and can be implemented with modifications within the scope of the above and below-described intent, and all of these modifications 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, and includes the following steps: a hydrogen gas conversion step in which the raw material mixed gas and an oxygen-containing gas are brought into contact with a catalyst to convert 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 nitrogen is removed by rectifying the gas obtained through the water removal step; an impurity gas adsorption separation step in which impurity gas is removed by bringing the gas obtained through the first nitrogen rectification separation step into contact with an adsorbent; and a helium rectification separation step in which helium gas is removed by rectifying the gas obtained through the impurity gas adsorption separation step.

[0014] According to an embodiment of the neon production method of the present invention, hydrogen gas contained in the raw material mixed gas is converted into water by contacting the hydrogen gas with a catalyst together with oxygen, and the resulting water is then removed, followed by removal of the impurity gas in the first nitrogen rectification separation step and the impurity gas adsorption separation step. In this manner, 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 the resulting water is removed (water removal step). This allows the oxygen used to convert hydrogen gas to water to 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 or oxygen, thereby reducing the load on the adsorption tower used in the impurity gas adsorption separation step. This allows for longer use of the adsorption tower and improved neon production efficiency. Furthermore, since there is no need to increase the number of adsorption towers or enlarge the adsorption towers to increase processing capacity, facility space can be saved and production costs can be reduced.

[0015] Each step will be described below.

[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. The catalyst used is one that reacts hydrogen with oxygen to produce water. Known catalysts can be used for reacting hydrogen with oxygen to produce water. The raw material mixed gas brought into contact with the catalyst may be, for example, the residual gas released from the top of the lower rectification column (so-called helium removal) when oxygen, nitrogen, argon, etc. are produced by liquefying and distilling raw material air. An oxygen-containing gas is used as the source of oxygen to be brought into contact with the catalyst. The oxygen-containing gas may be, for example, air or oxygen gas, with oxygen gas being preferred.

[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 for removing water using an adsorbent that adsorbs water and a method for removing water by membrane separation. Among these, a method for removing water using an adsorbent that adsorbs water is preferred. Known adsorbents that adsorb water can be used.

[0018] The raw material mixed gas may further contain carbon monoxide. When the raw material mixed gas contains carbon monoxide, the hydrogen gas conversion step may also serve as a carbon monoxide conversion step in which carbon monoxide and oxygen are brought into contact with a catalyst to convert the carbon monoxide into carbon dioxide. In this case, the catalyst may be a catalyst that converts hydrogen gas into water. By bringing carbon monoxide and oxygen into contact with a catalyst that converts hydrogen gas into water, the carbon monoxide can be converted into carbon dioxide. When the raw material mixed gas contains carbon monoxide, the water removal step may also serve as a carbon dioxide removal step in which carbon dioxide is removed from the gas obtained through the hydrogen gas conversion step.

[0019] When the raw material mixed gas contains carbon monoxide, the method may include a carbon monoxide conversion step, in which the carbon monoxide contained in the raw material mixed gas is converted into carbon dioxide, as a separate step from the hydrogen gas conversion step. The method for converting carbon monoxide to carbon dioxide is not particularly limited, and examples include a method using a catalyst that converts carbon monoxide into carbon dioxide by contacting carbon monoxide with oxygen. Known catalysts can be used as the catalyst that converts carbon monoxide into carbon dioxide by contacting carbon monoxide with oxygen. Furthermore, when the raw material mixed gas contains carbon monoxide, the method may include a carbon dioxide removal step, in which carbon dioxide is removed from the gas obtained through the carbon monoxide conversion step, as a separate step from the water removal step. When the carbon monoxide conversion step and the carbon dioxide removal step are included, the order of the hydrogen gas conversion step and the water removal step is not particularly limited. The hydrogen gas conversion step and the water removal step may be performed after the carbon monoxide conversion step and the carbon dioxide removal step, or the hydrogen gas conversion step and the carbon monoxide conversion step may be performed in any order, and then the water removal step and the carbon dioxide removal step may be performed in any order. Furthermore, after converting hydrogen to water and converting carbon monoxide to carbon dioxide in the hydrogen gas conversion step, the water removal step and the carbon dioxide removal step may be carried out as separate steps.

[0020] Methods for removing carbon dioxide contained in gas include, for example, a method using an adsorbent that adsorbs carbon dioxide and a method for 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 that removes water, or an adsorbent that selectively removes carbon dioxide may be used. Known adsorbents that selectively remove carbon dioxide can be used.

[0021] [First nitrogen rectification separation step] In the first nitrogen rectification separation step, the gas obtained through the water removal step (or the 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, with removal in a liquid state being preferred. When nitrogen is 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. Examples of impurity gases include nitrogen, oxygen, and hydrogen. Known adsorbents can be used to remove impurity gases. Removing impurity gases using an adsorbent can prevent nitrogen contained in the impurity gas from solidifying and clogging piping, etc., when refining neon in the helium rectification separation step described below.

[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 neon produced is not particularly limited, and may be gaseous neon or liquid neon, with liquid neon being preferred.

[0024] As an embodiment of the neon production method of the present invention, (1) a gas separation step may be included between the first nitrogen rectification separation step and the impurity gas adsorption separation step, in which the gas obtained through the first nitrogen rectification separation step is heat-exchanged with a refrigerant at -196°C to -210°C, followed by gas-liquid separation to separate the gas; or (2) a second nitrogen rectification separation step may be included between the impurity gas adsorption separation step and the helium rectification separation step, in which the gas obtained through the impurity gas adsorption separation step is rectified to remove nitrogen. Hereinafter, the embodiment including the gas separation step may be referred to as Embodiment 1, and the embodiment including the second nitrogen rectification separation step may be referred to as Embodiment 2.

[0025] (1) Embodiment 1 In the gas separation step of Embodiment 1, the gas obtained through the first nitrogen rectification separation step is heat-exchanged with a refrigerant at −196°C to −210°C, followed by gas-liquid separation to separate the gas. By exchanging heat between the gas obtained through the first nitrogen rectification separation step and the refrigerant, the nitrogen contained in the gas obtained through the first nitrogen rectification separation step is liquefied, and the fluid obtained by heat exchange is subjected to gas-liquid separation to remove the liquid, thereby further reducing the nitrogen contained in the gas separated. As a result, it is no longer necessary to repeat low-temperature adsorption twice as in Non-Patent Document 1. The gas obtained through the gas separation step is contacted with an adsorbent in the above-mentioned impurity gas adsorption separation step to remove residual impurity gas. By performing the gas separation step between the first nitrogen rectification separation step and the impurity gas adsorption separation step in this way, the load on the adsorption tower used in the impurity gas adsorption separation step can be reduced, thereby extending the usage time of the adsorption tower and further improving the neon production efficiency. The temperature of the refrigerant is not limited as long as it is a temperature at which the nitrogen contained in the gas obtained through the first nitrogen rectification separation step can be liquefied, but it is preferably as low as possible in the range of -196°C to -210°C, and more preferably -200°C to -210°C.

[0026] In the impurity gas adsorption separation step in the first embodiment, the impurity gas may be removed by a temperature swing adsorption method. The temperature at which the impurity gas is removed by the temperature swing adsorption method may be a low temperature of, for example, −100° C. or lower. By removing the impurity gas by the temperature swing adsorption method at −100° C. or lower, the concentration of the impurity gas can be reduced to a few ppb, thereby producing high-purity neon.

[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 a second rectification to remove nitrogen, the nitrogen contained in the gas to be supplied to the helium rectification separation step can be further reduced. The temperature of the refrigerant used in 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-mentioned 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 the second embodiment, the impurity gas may be removed by pressure swing adsorption. The temperature when removing the impurity gas by pressure swing adsorption may be, for example, room temperature (20°C ± 15°C). By removing the impurity gas by pressure swing adsorption at room temperature, the impurity gas concentration can be reduced to several ppm. By reducing the impurity gas concentration to several ppm, a refrigerant with a temperature below the solidification temperature of nitrogen can be used in the second nitrogen rectification separation step, thereby sufficiently removing nitrogen and producing high-purity neon.

[0029] According to an embodiment of the neon manufacturing method of the present invention, high-purity neon with a purity of 99.999% or more can be manufactured.

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

[0031] A first embodiment of a 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, and includes: a catalytic tower equipped with a catalyst with which the raw material mixed gas comes into contact with an oxygen-containing gas; water removal equipment for removing water contained in the gas from the catalytic 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 separating the fluid from the heat exchanger into gas and liquid; 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.

[0032] A second embodiment 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, and includes a catalytic tower equipped with a catalyst with which the raw material mixed gas comes into contact with an oxygen-containing gas, a water removal system for removing water contained in the gas from the catalytic tower, a first nitrogen removal rectification tower that rectifies the gas from the water removal system to remove nitrogen, a pressure swing adsorption tower that adsorbs impurity gases contained in the gas from the first nitrogen removal rectification tower by pressure swing adsorption, a second nitrogen removal rectification tower that rectifies the gas from the pressure swing adsorption tower to remove nitrogen, and a neon purification rectification tower that rectifies the gas from the second nitrogen removal rectification tower to remove helium gas and purify neon.

[0033] The first and second embodiments of the neon production apparatus are common in that they include a catalyst tower equipped with a catalyst with which the raw material mixed gas and the oxygen-containing gas come into contact, a water removal system that removes water contained in the gas from the catalyst tower, a first nitrogen removal rectification tower that rectifies the gas from the water removal system to remove nitrogen, an adsorption tower that adsorbs impurity gases (at least nitrogen), and a neon purification rectification tower that rectifies 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 described in detail with reference to the drawings. However, the present invention is not limited to the illustrated examples, and modifications may be made within the scope of the above and below-described purpose, and all such modifications are within the technical scope of the present invention. In each drawing, the same parts are designated by the same reference numerals to avoid redundant explanation. Furthermore, in each drawing, reference numerals may be omitted, and in such cases, reference should be made to the specification or other drawings.

[0035] (Embodiment 1) Figure 1 is a schematic diagram showing a neon production apparatus according to Embodiment 1 of the present invention. As shown in Figure 1, the neon production apparatus according to Embodiment 1 includes a catalyst tower 1, a water removal system 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 vessel 4.

[0036] The catalytic tower 1 is equipped with a catalyst that reacts hydrogen with oxygen to produce water. A raw material mixed gas is supplied to the catalytic tower 1 from a raw material mixed gas supply means 101. As the raw material mixed gas, for example, the residual gas released from the top of the lower rectification tower (so-called helium removal) when oxygen, nitrogen, argon, etc. are produced by liquefying and distilling raw material air may be used. An oxygen-containing gas is supplied to the catalytic tower 1 from an oxygen-containing gas supply means (not shown). As the oxygen-containing gas, for example, air or oxygen gas may be used, with oxygen gas being preferred. In the catalytic 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 to produce water. The produced water-containing gas is supplied from the catalytic tower 1 to a water removal facility 2.

[0037] The water removal equipment 2 can be, for example, an adsorption tower equipped with an adsorbent that adsorbs water, or a membrane separation device equipped with a membrane that can separate water from other gases. Among these, an adsorption tower is preferably used. Alternatively, an adsorption tower and a membrane separation device may be used in combination. While FIG. 1 shows an example configuration equipped with one water removal equipment 2, the number of water removal equipment 2 is not limited to one and may be two or more. 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 column 3.

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

[0039] When the raw material mixed gas contains carbon monoxide, the neon production apparatus may include, in addition to catalytic tower 1, a second catalytic tower equipped with a catalyst with which the raw material mixed gas comes into contact. The second catalytic tower may be provided with a catalyst that converts carbon monoxide to carbon dioxide by contacting carbon monoxide with oxygen. The catalyst that converts carbon monoxide to carbon dioxide by contacting carbon monoxide with oxygen may, for example, be a catalyst that converts hydrogen gas to water. When the neon production apparatus includes the second catalytic tower, the order of arrangement of catalytic tower 1 and the second catalytic tower is not particularly limited. The second catalytic tower may be arranged downstream of catalytic tower 1, or the second catalytic tower may be arranged upstream of catalytic tower 1. Furthermore, when the raw material mixed gas contains carbon monoxide, the neon production apparatus may include, in addition to water removal equipment 2, a carbon dioxide removal equipment that removes carbon dioxide contained in the gas supplied from the second catalytic tower. When the neon production apparatus includes a second catalytic tower, the arrangement order of the catalytic tower 1 and the water removal equipment 2 is not particularly limited. The catalytic tower 1 and the water removal equipment 2 may be arranged in this order, followed by the second catalytic tower, or the catalytic tower 1 and the second catalytic tower may be arranged in any order, followed by the water removal equipment 2 in any order. When the neon production apparatus includes a carbon dioxide removal equipment, the arrangement order of the catalytic tower 1 and the water removal equipment 2 is not particularly limited. The catalytic tower 1 and the water removal equipment 2 may be arranged in this order, followed by the carbon dioxide removal equipment, or the catalytic tower 1 may be arranged, followed by the water removal equipment 2 and the carbon dioxide removal equipment in any order. When the neon production apparatus includes a second catalytic tower and a carbon dioxide removal equipment, the arrangement order of the catalytic tower 1 and the water removal equipment 2 is not particularly limited. The catalytic tower 1 and the water removal equipment 2 may be arranged in this order, followed by the second catalytic tower and the carbon dioxide removal equipment in this order, or the catalytic tower 1 and the second catalytic tower may be arranged in any order, followed by the water removal equipment 2 and the carbon dioxide removal equipment in any order. Alternatively, the neon production apparatus may include the catalytic tower 1, but not the second catalytic tower, and may include both the water removal equipment 2 and the carbon dioxide removal equipment.

[0040] Examples of carbon dioxide removal equipment include a carbon dioxide adsorption tower equipped with an adsorbent that adsorbs carbon dioxide, and a membrane separator that removes carbon dioxide by membrane separation. When carbon dioxide is removed using an adsorbent, the adsorbent used in the carbon dioxide removal equipment may be an adsorbent that removes water, or an adsorbent that selectively removes carbon dioxide.

[0041] A heat exchanger 111 may be provided between the water removal facility 2 and the first nitrogen removal rectification column 3. A refrigerant is supplied to the heat exchanger 111 from a refrigerant supply means 111a, and heat is exchanged between the refrigerant and the gas supplied from the water removal facility 2. Nitrogen gas, for example, may be used as the refrigerant. As the nitrogen gas, for example, gas accumulated at the top of a vessel 31, which will be described later, may be used. In this case, a path for discharging helium gas may be connected to the top of the vessel 31.

[0042] The first nitrogen removal rectification column 3 is a single-stage rectification column, and the gas introduced into the first nitrogen removal rectification column 3 is cryogenically liquefied and separated by utilizing the difference in boiling points of the components, with the high-boiling components (nitrogen and oxygen) in the gas being liquefied and accumulating at the bottom, and the low-boiling components (neon and helium) accumulating as gas at the top. The number of theoretical plates provided in the first nitrogen removal rectification column 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 column 3. A heat medium is supplied to the reboiler 3a from a heat medium supply means 3b, and heat exchange occurs between the heat medium and the liquid liquefied in the first nitrogen removal rectification column 3. The heat medium after heat exchange is discharged from a line 3c. Nitrogen gas, for example, may be used as the heat medium. The gas accumulated at the top of a vessel 31, which will be described later, may also be used as the nitrogen gas. The liquid of high-boiling components accumulated at the bottom of the first nitrogen removal rectification column 3 may be discharged to the outside of the system from a line (not shown) provided at the bottom of the first nitrogen removal rectification column 3. The discharged liquid may be supplied, for example, to a vessel 31 equipped with a condenser 31a, which will be described later, and used as a refrigerant.

[0044] The first nitrogen removal rectification column 3 is usually equipped with a vessel 31 equipped with a condenser 31a. In Figure 1, the vessel 31 is provided above the first nitrogen removal rectification column 3. The gas of low boiling point components accumulated at the top of the first nitrogen removal rectification column 3 is supplied from the first nitrogen removal rectification column 3 via a line 3d to the condenser 31a provided in the vessel 31.

[0045] A refrigerant is supplied to vessel 31 from refrigerant supply means 31d, and heat is exchanged between the refrigerant and the gas supplied to condenser 31a. For example, a liquid discharged from a path (not shown) provided at the bottom of first nitrogen removal rectification column 3 may be used as the refrigerant. Heat is exchanged between the gas supplied to condenser 31a and the refrigerant, producing a liquid and a gas. The produced liquid may be returned from condenser 31a to first nitrogen removal rectification column 3 via path 31c. Meanwhile, the produced gas is supplied from condenser 31a to heat exchanger 4a provided in vessel 4 via path 31b. Because nitrogen gas accumulates at the top of vessel 31, a path for discharging nitrogen gas to the outside of the system may be connected to the top of vessel 31.

[0046] A refrigerant is supplied to the vessel 4 from a refrigerant supply means 4b, and heat is exchanged between the refrigerant and the gas supplied to the heat exchanger 4a. A fluid at −196°C to −210°C is used as the refrigerant. The fluid obtained by heat exchange in the heat exchanger 4a is supplied to the gas-liquid separator 5 and separated into a liquid and a gas. In this way, the gas obtained 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 separation is performed 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 to the outside of the system through a line 5b provided at the bottom of the gas-liquid separator 5. The discharged liquid may be used as a refrigerant. Alternatively, 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 columns 6a and 6b. The temperature swing adsorption towers 6a, 6b are equipped with an adsorbent that adsorbs impurity gases. The temperature swing adsorption towers 6a, 6b need only be filled with an adsorbent that can remove at least nitrogen, and may also be filled with an adsorbent that can remove hydrogen and water in addition to nitrogen. When the raw material mixed gas contains carbon monoxide, the temperature swing adsorption towers 6a, 6b may also be filled with an adsorbent that can remove carbon monoxide and carbon dioxide. Known adsorbents can be used for this purpose. A valve (not shown) may be disposed upstream of the temperature swing adsorption towers 6a, 6b and configured to be switchable.

[0047] In the temperature swing adsorption towers 6a and 6b, impurity gases contained in the gas supplied from the gas-liquid separator 5 are adsorbed by temperature swing adsorption. The temperature when removing the impurity gases by temperature swing adsorption may be, for example, a low temperature of −100°C or lower. By removing the impurity gases by temperature swing adsorption at −100°C or lower, the impurity gas concentration can be reduced to several ppb, making it possible to produce high-purity neon. While FIG. 1 shows an example configuration equipped with two temperature swing adsorption towers, 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 tower 7.

[0048] In neon purification rectification column 7, the gas supplied from temperature swing adsorption columns 6a and 6b is rectified to remove helium gas and purify neon. Neon purification rectification column 7 is a single rectification column, and the gas introduced into neon purification rectification column 7 is subjected to cryogenic liquefaction separation by utilizing the difference in boiling points of the components, with the high-boiling component (neon) in the gas being liquefied and accumulating at the bottom, and the low-boiling component (helium) accumulating as a gas at the top. The number of theoretical plates provided in neon purification rectification column 7 is not particularly limited and may be, for example, 5 to 10.

[0049] The neon purification rectification column 7 is typically equipped with a vessel 71 equipped with a condenser 71a. In FIG. 1 , the vessel 71 is provided above the neon purification rectification column 7. The gas of low-boiling-point components accumulated at the top of the neon purification rectification column 7 is helium, and is supplied from the neon purification rectification column 7 to a condenser 71a equipped in the vessel 71 via a line 7e. A refrigerant is supplied to the vessel 71 from a 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 having a temperature of −259° C. to −253° C. may be used, and liquefied hydrogen may be used as the fluid having a temperature of −259° C. to −253° C. The gas supplied to the condenser 71a exchanges heat 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 a line 71d and may be recovered as helium gas 71c. Meanwhile, the produced liquid may be returned from condenser 71a via line 71e to neon purification distillation column 7. While Fig. 1 shows an example of a configuration in which heat exchange is performed by supplying a refrigerant to vessel 71, heat exchange may also be performed by cooling the inside of vessel 71 to -270°C to -253°C, for example, using 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 a heat medium supply means 7b, and heat exchange occurs between the heat medium and the liquid liquefied in the neon purification rectification column 7. The heat medium after heat exchange is discharged through a line 7c. As the heat medium, for example, helium gas may be used. As the helium gas, for example, helium gas 71c recovered from the condenser 71a may be used.

[0051] The liquid high-boiling components accumulated at the bottom of neon purification rectification column 7 is neon, and is discharged to the outside of the system through line 7d provided at the bottom of neon purification rectification column 7 and recovered as liquefied neon 201. Note that although FIG. 1 shows an example of a configuration in which liquid neon is recovered, gaseous neon may also be recovered.

[0052] A heat exchanger 112 may be provided between the temperature swing adsorption columns 6a, 6b and the neon purification rectification column 7. A refrigerant is supplied to the heat exchanger 112 from a refrigerant supply means 112a, and heat is exchanged between the refrigerant and the gas supplied from the temperature swing adsorption columns 6a, 6b. For example, helium gas may be used as the refrigerant. For example, helium gas 71c recovered from the condenser 71a or helium gas accumulated at the top of the container 71 may be used as the helium gas. 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] 2 is a schematic diagram showing a neon production apparatus according to a second embodiment of the present invention. As shown in FIG. 2, the neon production apparatus according to the second embodiment includes a catalyst tower 1, a water removal system 2, a first nitrogen removal rectification tower 3, pressure swing adsorption towers 8a and 8b, a second nitrogen removal rectification tower 9, and a neon purification rectification tower 7.

[0054] In the second embodiment, 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 a path 3d. The gas produced in the condenser 31a is supplied from the condenser 31a to the pressure swing adsorption columns 8a and 8b via a path 31b. The pressure swing adsorption columns 8a and 8b are equipped with an adsorbent that adsorbs impurity gases. The pressure swing adsorption columns 8a and 8b are only required to be filled with an adsorbent capable of removing at least nitrogen, and may be further filled with an adsorbent that can remove hydrogen and water in addition to nitrogen. When the raw material mixed gas contains carbon monoxide, the columns may be further filled with an adsorbent that can also remove carbon monoxide and carbon dioxide. Known adsorbents may be used as such adsorbents. A valve (not shown) may be disposed upstream of the pressure swing adsorption columns 8a and 8b and configured to be switchable.

[0055] In the pressure swing adsorption towers 8a and 8b, impurity gases contained in the gas supplied from the condenser 31a are adsorbed by pressure swing adsorption. The temperature when removing impurity gases by pressure swing adsorption may be, for example, room temperature (20°C ± 15°C). By removing impurity gases by pressure swing adsorption at room temperature, the impurity gas concentration can be reduced to several ppm, making it possible to produce high-purity neon. While FIG. 2 shows an example configuration including two pressure swing adsorption towers, the number of pressure swing adsorption towers is not limited to two and may be three or more. The gas from which impurity gases have been removed in the pressure swing adsorption towers 8a and 8b is supplied from the pressure swing adsorption towers 8a and 8b to the second nitrogen removal rectification tower 9.

[0056] The second nitrogen removal rectification column 9 is a single-stage rectification column. The gas introduced into the second nitrogen removal rectification column 9 is cryogenically liquefied and separated by utilizing the difference in boiling points of the 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 as gas at the top. The number of theoretical plates provided in the second nitrogen removal rectification column 9 is not particularly limited and may be, for example, 8 to 15. A reboiler 9a is provided at the bottom of the second nitrogen removal rectification column 9. A refrigerant is supplied to the reboiler 9a from a heat medium supply means 9b, and heat exchange occurs between the refrigerant and the liquid liquefied in the second nitrogen removal rectification column 9. The refrigerant after heat exchange is discharged through a line 9c. As the refrigerant, for example, a fluid at −259° C. to −253° C. may be used. As the fluid at −259° C. to −253° C., liquefied hydrogen may be used. 2 shows an example of a configuration in which a refrigerant is supplied to reboiler 9a to perform heat exchange, but heat exchange may also be performed by cooling the inside of vessel 71 to −270° C. to −253° C. using, for example, a cooling means (not shown) to cool the inside of second nitrogen removal rectification column 9. The liquid of high-boiling components accumulated at the bottom of second nitrogen removal rectification column 9 may be discharged to the outside of the system through line 9e provided at the bottom of second nitrogen removal rectification column 9 and recovered as liquid 301. The discharged liquid 301 may be supplied to vessel 31 equipped with the above-mentioned condenser 31a and used as the refrigerant supplied from refrigerant supply means 31d.

[0057] The second nitrogen removal rectification column 9 is usually equipped with a vessel 91 equipped with a condenser 91a. In FIG. 2 , the vessel 91 is provided above the second nitrogen removal rectification column 9. The gas of low-boiling components accumulated at the top of the second nitrogen removal rectification column 9 is supplied from the second nitrogen removal rectification column 9 via line 9d to the condenser 91a equipped in the vessel 91. A refrigerant is supplied to the vessel 91 from a refrigerant supply means 91e, and heat exchange occurs between the refrigerant and the gas supplied to the condenser 91a. The refrigerant may be, for example, a liquid discharged from a line (not shown) provided at the bottom of the first nitrogen removal rectification column 3. The gas supplied to the condenser 91a exchanges heat with the refrigerant, producing a liquid and a gas. The produced liquid may be returned from the condenser 91a to the second nitrogen removal rectification column 9 via line 91c. Meanwhile, the produced gas is supplied from the vessel 91 to the neon purification rectification column 7 via line 91b.

[0058] A heat exchanger 112 may be provided between the pressure swing adsorption columns 8a, 8b and the second nitrogen removal rectification column 9. A refrigerant is supplied to the heat exchanger 112 from a refrigerant supply means 112a, and heat is exchanged between the refrigerant and the gas supplied from the pressure swing adsorption columns 8a, 8b. For example, helium gas may be used as the refrigerant. For example, helium gas 71c recovered from a condenser 71a (described later) or helium gas accumulated at the top of a vessel 71 (described later) may be used as the helium gas. When the helium gas accumulated at the top of the vessel 71 is used as the refrigerant, a path for discharging the helium gas may be connected to the top of the vessel 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 rectification column, and the gas introduced into the neon purification rectification column 7 is subjected to cryogenic liquefaction separation by utilizing the difference in boiling points of the components, with the high-boiling component (neon) in the gas being liquefied and accumulating at the bottom, and the low-boiling component (helium) accumulating as a gas at the top. 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 typically equipped with a vessel 71 equipped with a condenser 71a. In FIG. 2 , the vessel 71 is provided above the neon purification rectification column 7. The gas of low-boiling-point components accumulated at the top of the neon purification rectification column 7 is helium, and is supplied from the neon purification rectification column 7 to a condenser 71a equipped in the vessel 71 via a line 7e. A refrigerant is supplied to the vessel 71 from a 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 having a temperature of −259° C. to −253° C. may be used, and liquefied hydrogen may be used as the fluid having a temperature of −259° C. to −253° C. The gas supplied to the condenser 71a exchanges heat 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 a line 71d and may be recovered as helium gas 71c. Meanwhile, the produced liquid may be returned from condenser 71a via line 71e to neon purification distillation column 7. While Fig. 2 shows an example of a configuration in which heat exchange is performed by supplying a refrigerant to vessel 71, heat exchange may also be performed by, for example, cooling the inside of vessel 71 to -270°C to -253°C using a cooling means (not shown).

[0061] 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 a heat medium supply means 7b, and heat exchange occurs between the heat medium and the liquid liquefied in the neon purification rectification column 7. The heat medium after heat exchange is discharged through line 7c. Helium gas, for example, may be used as the heat medium. Helium gas 71c recovered from condenser 71a may be used as the helium gas. The liquid high-boiling point component accumulated at the bottom of the neon purification rectification column 7 is neon, which is discharged to the outside of the system through line 7d provided at the bottom of the neon purification rectification column 7 and recovered as liquefied neon 201. While FIG. 2 shows an example of a configuration in which liquid neon is recovered, gaseous neon may also be recovered.

[0062] According to the first and second embodiments of the neon manufacturing apparatus of the present invention, high-purity neon with a purity of 99.999% or more can be manufactured.

[0063] In this way, 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 conventional technologies, thereby reducing greenhouse gas emissions and contributing to some of the activities for the Sustainable Development Goals (SDGs).

[0064] This application claims the benefit of priority based on Japanese Patent Application No. 2023-207754, filed on December 8, 2023. The entire contents of the specification of Japanese Patent Application No. 2023-207754 are incorporated herein by reference.

[0065] REFERENCE SIGNS LIST 1 Catalyst tower 2 Water removal equipment 3 First nitrogen removal rectification tower 4 Vessel 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 contacting the raw material mixed gas and an oxygen-containing gas 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 contacting the gas obtained through the first nitrogen rectification separation step with an adsorbent to remove impurity gas; and a helium rectification separation step of rectifying the gas obtained through the impurity gas adsorption separation step to remove helium gas.

2. The method according to claim 1, further comprising a gas separation step between the first nitrogen rectification separation step and the impurity gas adsorption separation step, in which the gas obtained through the first nitrogen rectification separation step is heat exchanged with a refrigerant at -196°C to -210°C, and then the gas is separated by gas-liquid separation, and in the impurity gas adsorption separation step, the gas obtained through the gas separation step is contacted with an adsorbent.

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

4. The method of claim 1, further comprising a second nitrogen rectification separation step between the impurity gas adsorption separation step and the helium rectification separation step, in which the gas obtained through the impurity gas adsorption separation step is rectified to remove nitrogen, and in the helium rectification separation step, the gas obtained through the second nitrogen rectification separation step is rectified to remove helium gas.

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

6. The method according to claim 1, wherein the raw material mixed gas further contains carbon monoxide, and the method further comprises a carbon monoxide conversion step of converting the carbon monoxide contained in the raw material mixed gas into carbon dioxide.

7. The method according to claim 1, wherein the raw material mixed gas further contains carbon monoxide, and the method comprises: 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.

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 comes into contact with an oxygen-containing gas; 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 separating the fluid from the heat exchanger into gas and liquid; 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.

9. 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 comes into contact with an oxygen-containing gas; 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.

10. The manufacturing apparatus according to claim 8 or 9, further comprising: a second catalyst tower provided with a catalyst with which the raw material mixed gas comes into contact; and 11. The manufacturing apparatus according to claim 8 or 9, wherein the raw material mixed gas further contains carbon monoxide, and further comprising: a second catalytic 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 catalytic tower.

Images