Neon refining apparatus and method

Abstract

A neon refining device and a neon refining method are provided that can improve the efficiency of refining neon. [Solution] The neon purification apparatus of the present invention comprises a first adsorption section that adsorbs and removes nitrogen and argon from a raw material gas, a cooling section that cools the raw material gas from which nitrogen and argon have been adsorbed and removed in the first adsorption section to produce a cooled gas, and a second adsorption section that adsorbs and removes one or both of nitrogen and argon from the cooled gas.

Description

[Technical field]

[0001] The present invention relates to a neon purification apparatus and a neon purification method. [Background technology]

[0002] Conventionally, there has been known a neon refining apparatus that refines neon from a raw material gas containing neon, helium, nitrogen, and hydrogen. Patent Document 1 discloses this type of neon refining apparatus.

[0003] The neon purification apparatus described in Patent Document 1 includes a hydrogen oxidation section that oxidizes hydrogen, a moisture removal section that adsorbs and removes moisture, a liquefaction removal section that liquefies and removes nitrogen, a removal section that removes residual nitrogen and the like by low-temperature adsorption, and a distillation section. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] U.S. Pat. No. 1,076,7923 Summary of the Invention [Problem to be solved by the invention]

[0005] However, the neon refining device described in Patent Document 1 still has room for improvement in terms of efficiency in refining neon.

[0006] An object of the present invention is to provide a neon refining device and a neon refining method that can improve the efficiency of refining neon. [Means for solving the problem]

[0007] A neon purification apparatus according to a first aspect of the present invention comprises: (1) a first adsorption section that adsorbs and removes nitrogen and argon from the source gas; a cooling section for cooling the raw material gas from which nitrogen and argon have been adsorbed and removed in the first adsorption section to produce a cooled gas; and a second adsorption section that adsorbs and removes one or both of nitrogen and argon from the cooling gas.

[0008] As one embodiment of the present invention, a neon purification apparatus includes: (2) The neon purification apparatus according to (1) above, wherein the amount of argon adsorbed and removed from the raw material gas by the first adsorption section is greater than the amount of argon adsorbed and removed from the cooling gas by the second adsorption section.

[0009] As one embodiment of the present invention, a neon purification apparatus includes: (3) The neon purification apparatus according to (1) or (2) above, wherein the concentration of argon in the raw gas after nitrogen and argon are adsorbed and removed in the first adsorption section is 10 volppm or less.

[0010] As one embodiment of the present invention, a neon purification apparatus includes: (4) Before being supplied to the first adsorption section, oxygen gas containing argon is added to the raw material gas. The neon purification device according to any one of (1) to (3) above.

[0011] As one embodiment of the present invention, a neon purification apparatus includes: (5) A neon purification method using the neon purification device according to any one of (1) to (4) above. Effect of the Invention

[0012] According to the present invention, it is possible to provide a neon refining device and a neon refining method that can improve the efficiency of refining neon. [Brief description of the drawings]

[0013] [Figure 1]FIG. 1 illustrates a neon purification apparatus according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of a neon refining apparatus and a neon refining method according to the present invention will be described by way of example with reference to the drawings.

[0015] FIG. 1 is a diagram showing a neon purification apparatus 100 as one embodiment of the neon purification apparatus according to the present invention. Crude neon gas containing neon, helium, nitrogen, and hydrogen is supplied to the neon purification apparatus 100. The neon purification apparatus 100 is an apparatus for purifying neon from the crude neon gas. The crude neon gas is produced, for example, as a by-product when oxygen, nitrogen, and argon are produced from raw air using an air separation unit. The main composition of the crude neon gas supplied to the neon purification apparatus 100 is, for example, 50 vol% neon, 15 vol% helium, 2 vol% hydrogen, and the remainder nitrogen. However, the composition of the crude neon gas is not limited to the above and may vary depending on the configuration of the air separation unit that produces the crude neon gas.

[0016] The buffer container 1 receives the crude neon gas supplied from the crude neon gas supply line 101 and the reflux gas that is refluxed in part of the process of the neon purification apparatus 100, and stores and holds the mixture as a raw material gas. Examples of the reflux gas include, but are not limited to, the gas exhausted from the moisture removal section 6, the gas exhausted from the first adsorption section 7, and the gas exhausted from the distillation column 13. The buffer container 1 may not receive the reflux gas and may store only the crude neon gas as the raw material gas. The neon purification apparatus 100 may not be equipped with the buffer container 1. In this case, the crude neon gas and the reflux gas may be mixed, for example, in the crude neon gas supply line 101 to be used as the raw material gas.

[0017] The raw material gas discharged from the buffer vessel 1 is pressurized to a pressure required for the process by the compressor 2. The raw material gas pressurized by the compressor 2 is supplied to the hydrogen oxidation unit 3. The raw material gas supplied to the hydrogen oxidation unit 3 may be heated by a heater before being supplied to the hydrogen oxidation unit 3, or may be heated by a heater included in the hydrogen oxidation unit 3 after being supplied to the hydrogen oxidation unit 3. In addition, oxygen gas is added to the raw material gas before being supplied to the hydrogen oxidation unit 3. As a result, hydrogen and oxygen in the raw material gas react in the hydrogen oxidation unit 3, and moisture is generated by oxidizing hydrogen. Note that, as will be described in detail later, the oxygen gas contains argon in addition to oxygen. The hydrogen oxidation unit 3 is equipped with a catalyst that promotes the reaction between hydrogen and oxygen. The hydrogen oxidation unit 3 of this embodiment includes a hydrogen oxidation tower, and the catalyst is filled in the hydrogen oxidation tower. Examples of catalysts include platinum, palladium, copper, and the like, but are not limited to these. The raw material gas whose temperature has increased due to the reaction heat of the catalytic reaction in the hydrogen oxidation unit 3 is introduced into a cooler 4 and cooled to room temperature or lower. The raw material gas cooled by the cooler 4 is introduced into the normal temperature gas-liquid separator 5. As a result, the moisture condensed by the cooling in the cooler 4 is introduced into the liquid phase side, and the rest The other components are separated into the gas phase.

[0018] The raw material gas separated into the gas phase by the room temperature gas-liquid separator 5 is introduced into the moisture removal section 6. The moisture removal section 6 is a device that removes moisture and carbon dioxide from the raw material gas by a temperature swing adsorption (TSA) method (hereinafter simply referred to as the "TSA method"), which repeats adsorption and regeneration due to temperature difference.

[0019] The moisture removal section 6 includes an adsorbent. The adsorbent adsorbs and removes moisture and carbon dioxide from the raw material gas. The moisture adsorbed and removed by the moisture removal section 6 is generated by the reaction of hydrogen contained in the raw material gas with oxygen in the hydrogen oxidation section 3. The carbon dioxide adsorbed and removed by the moisture removal section 6 is generated by the reaction of carbon monoxide contained in the raw material gas with oxygen in the hydrogen oxidation section 3. Examples of adsorbents included in the moisture removal section 6 include, but are not limited to, zeolite, silica gel, activated alumina, and the like.

[0020] The moisture removal section 6 of this embodiment includes at least two adsorption towers. Each of the at least two adsorption towers is filled with the above-mentioned adsorbent. During operation of the neon purification apparatus 100, an adsorption process for adsorbing and removing moisture and carbon dioxide from the raw gas is performed in at least one of the at least two adsorption towers, and a regeneration process for desorbing moisture and carbon dioxide from the adsorbent is performed in at least another adsorption tower. The adsorption process and the regeneration process are performed by switching between the at least two adsorption towers of the moisture removal section 6. In the regeneration process, a regeneration gas for promoting desorption of moisture and carbon dioxide from the adsorbent is supplied to the moisture removal section 6. This regeneration gas may be supplied to the moisture removal section 6 in a state heated by an external heater or the like.

[0021] The neon purification apparatus 100 of this embodiment includes a dry gas supply line 103 that supplies dry gas to the moisture removal section 6 from outside the neon purification apparatus 100. This allows the dry gas to be supplied to the moisture removal section 6 as a regeneration gas in the regeneration process of the moisture removal section 6. The dry gas may be prepared separately from the crude neon gas. However, as the regeneration gas, at least one of a separated gas mainly composed of helium separated and removed from the raw material gas in the helium removal section 11 described later, and a mixed gas in which a rinse gas supplied to the first adsorption section 7 described later and a desorbed gas such as nitrogen desorbed from the first adsorption section 7 are mixed may be used. If necessary, a part of the raw material gas from which moisture and carbon dioxide have been removed in the moisture removal section 6 can also be used as the regeneration gas.

[0022] The moisture and carbon dioxide desorbed from the adsorbent in the regeneration step of the moisture removal unit 6 are mixed with the regeneration gas and discharged from the moisture removal unit 6 through the exhaust line 104 together with the blowdown gas generated when switching between the adsorption step and the regeneration step. At this time, at least a portion of the gas discharged from the moisture removal unit 6 through the exhaust line 104 may be supplied to the buffer container 1 as a reflux gas in order to improve the recovery rate of neon. In addition, all of the gas discharged from the moisture removal unit 6 through the exhaust line 104 may be discharged outside the system of the neon purification apparatus 100.

[0023] The raw gas from which moisture and carbon dioxide have been removed by the moisture removal section 6 is supplied to the first adsorption section 7. The first adsorption section 7 removes most of the nitrogen contained in this raw gas. The nitrogen adsorbed and removed by the first adsorption section 7 is contained in the crude neon gas. Furthermore, the first adsorption section 7 adsorbs and removes argon from the raw gas in addition to nitrogen. This can improve the efficiency of refining neon by the neon purification device 100. This will be described in detail below.

[0024] The raw material gas supplied to the first adsorption section 7 contains argon. This argon is contained in oxygen gas that is added to the raw material gas before it is supplied to the first adsorption section 7 (more specifically, the hydrogen oxidation section 3). Specifically, argon is a common industrial oxygen gas produced by liquefying and distilling air. The oxygen gas used in the process contains about 2000 to 4000 volppm of argon in addition to oxygen, which is the main component. This argon is not removed from the raw material gas between the hydrogen oxidation section 3 and the moisture removal section 6. Therefore, the raw material gas containing argon is supplied to the first adsorption section 7. The concentration of argon in the raw material gas supplied to the first adsorption section 7 depends on the argon concentration in the oxygen gas and the amount of oxygen gas added to the raw material gas, and is generally about 10 to 500 volppm. This argon in the raw material gas solidifies in the cold box 20, causing problems such as blocking the line, and is a factor that reduces the purity of the product neon, so it needs to be sufficiently removed from the raw material gas during the process.

[0025] Although details will be described later, the neon purification apparatus 100 of this embodiment includes a first heat exchanger 8 as a cooling unit that cools the raw gas to produce a cooling gas, and a second adsorption unit 9 that adsorbs and removes one or both of nitrogen and argon from the cooling gas. A circulating refrigerant is supplied from a cryogenic refrigerator 21 to the first heat exchanger 8 as a cooling unit. Here, when the amount of argon in the raw gas supplied to the second adsorption unit 9 is large, it is necessary to increase the amount of adsorbent in the second adsorption unit 9 and increase the amount of argon adsorbed and removed from the raw gas in the second adsorption unit 9 in order to suppress the occurrence of the above-mentioned malfunctions. However, when the amount of adsorbent in the second adsorption unit 9 increases, the volume of the adsorption tower of the second adsorption unit 9 containing the adsorbent also increases. When the volume of the adsorption tower increases, the volume of the cold box 20 increases in this embodiment. This increases the surface area of ​​the cold box 20, and the amount of heat entering the cold box 20 from the outside increases. As a result, in order to maintain a low temperature inside cold box 20, it becomes necessary to increase the operating power of cryogenic refrigerator 21, which supplies circulating refrigerant to first heat exchanger 8 inside cold box 20. That is, if the amount of argon in the raw material gas supplied to second adsorption section 9 increases and the amount of adsorbent in second adsorption section 9 increases accordingly, the operating power of cryogenic refrigerator 21 increases, which may reduce the efficiency of refining neon.

[0026] In contrast, the first adsorption unit 7 adsorbs and removes argon from the raw material gas in addition to nitrogen. The presence of such a first adsorption unit 7 makes it possible to remove argon from the raw material gas before the cooling gas is supplied to the second adsorption unit 9. This makes it possible to reduce the amount of argon in the cooling gas supplied to the second adsorption unit 9, suppressing an increase in the need to increase the amount of adsorbent in the second adsorption unit 9 and suppressing an increase in the operating power of the cryogenic refrigerator 21. As a result, the efficiency of refining neon can be improved.

[0027] The amount of argon adsorbed and removed from the raw material gas by the first adsorption unit 7 in this embodiment is greater than the amount of argon adsorbed and removed from the cooling gas by the second adsorption unit 9. Specifically, the first adsorption unit 7 adsorbs and removes preferably 50% or more of the argon contained in the raw material gas, more preferably 70% or more of the argon, and even more preferably 90% or more of the argon, from the raw material gas. In this way, the amount of argon in the cooling gas supplied to the second adsorption unit 9 can be sufficiently reduced, and an increase in the operating power of the cryogenic refrigerator 21 can be further suppressed. As a result, the efficiency of refining neon can be further improved.

[0028] As described above, if the amount of argon in the cooling gas supplied to the second adsorption unit 9 is large, the operating power of the cryogenic refrigerator 21 increases, which may reduce the efficiency of refining neon. Also, if the amount of nitrogen in the cooling gas supplied to the second adsorption unit 9 is large, for the same reason as for argon, the operating power of the cryogenic refrigerator 21 increases, which may reduce the efficiency of refining neon. Therefore, from the viewpoint of improving the efficiency of refining neon, the concentrations of nitrogen and argon in the source gas after nitrogen and argon are adsorbed and removed in the first adsorption unit 7 are preferably 10 volppm or less, and more preferably 1 volppm or less, respectively.

[0029] In addition, when oxygen is contained in the raw material gas, the oxygen may be removed from the raw material gas by the first adsorption section 7 in addition to nitrogen and argon. This oxygen is contained in the oxygen gas added to the raw material gas before being supplied to the first adsorption section 7 (more specifically, the hydrogen oxidation section 3). Specifically, this oxygen is the oxygen contained in the oxygen gas that is not removed from the raw material gas by the hydrogen oxidation section 3, the cooler 4, and the moisture removal section 6 and remains in the raw material gas. If the amount of oxygen in the cooling gas supplied to the second adsorption section 9 is large, for the same reason as for argon and nitrogen, the operating power of the cryogenic refrigerator 21 may increase, and the efficiency of refining neon may decrease. Therefore, from the viewpoint of improving the efficiency of refining neon, the concentration of oxygen in the raw material gas after nitrogen, argon, and oxygen are adsorbed and removed by the first adsorption section 7 is preferably 10 volppm or less, more preferably 1 volppm or less.

[0030] The first adsorption unit 7 of this embodiment is an apparatus that removes nitrogen from the source gas by a Vacuum Pressure Swing Adsorption (VPSA) system (hereinafter simply referred to as the "VPSA system") in which adsorption and regeneration are repeated by pressure swing using a vacuum pump. However, the first adsorption unit 7 may be of the TSA system or may be of the Pressure Swing Adsorption (PSA) system (hereinafter simply referred to as the "PSA system") that does not use a vacuum pump.

[0031] The first adsorption section 7 includes an adsorbent. Examples of the adsorbent included in the first adsorption section 7 include, but are not limited to, zeolite and activated carbon. The first adsorption section 7 of this embodiment includes at least two adsorption towers. Each of these at least two adsorption towers is filled with the above-mentioned adsorbent. It is preferable that the first adsorption section 7 includes three or more adsorption towers to reduce the loss of neon. During operation of the neon purification device 100, an adsorption process is performed in at least one adsorption tower to remove nitrogen, argon, and oxygen from the raw gas, and a regeneration process is performed in at least another adsorption tower to desorb the nitrogen, argon, and oxygen adsorbed on the adsorbent. The adsorption process and the regeneration process are performed by switching between at least two adsorption towers of the first adsorption section 7. In addition, in order to improve the recovery rate of neon, a pressure equalization process may be performed at the end of the adsorption process to distribute the pressure of the adsorption tower in which the adsorption process was performed to another adsorption tower.

[0032] The adsorption tower of the first adsorption section 7 in this embodiment is a so-called room temperature adsorption tower that is operated at room temperature. In this specification, "room temperature" refers to a temperature within the range of 5 to 40°C.

[0033] In the neon purification apparatus 100, the duration of each process and the amount of adsorbent are adjusted in order to efficiently remove the impurities in the raw gas to be removed. Specifically, in the neon purification apparatus 100 of this embodiment, the first adsorption unit 7 is operated under operating conditions suitable for adsorbing both nitrogen and argon. More specifically, the duration of the adsorption process and the regeneration process of the first adsorption unit 7 is set to a length suitable for removing both the nitrogen and argon components. It is also possible to set the amount of adsorbent provided in the first adsorption unit 7 to be equal to or greater than the amount of adsorbent required when removing only one of nitrogen and argon. However, the operating conditions of the first adsorption unit 7 are not limited to the above and may be appropriately adjusted depending on the specific configuration of the neon purification apparatus, etc.

[0034] The regeneration process carried out in the first adsorption section 7 may include a depressurization process, a vacuum exhaust process, and an exhaust regeneration process. The depressurization process is a process of releasing the pressure remaining in the adsorption tower to the outside after the adsorption process, or after the pressure equalization process in the case where the pressure equalization process is carried out after the adsorption process. The vacuum exhaust process is a process of desorbing the nitrogen, argon, and oxygen adsorbed to the adsorbent by evacuating the adsorption tower using a vacuum pump. The exhaust regeneration process is a process of further promoting the desorption of nitrogen, argon, and oxygen by flowing a rinse gas into the adsorption tower while evacuating the adsorption tower using a vacuum pump. Here, it is desirable for the gas used as the rinse gas to be a gas that does not contain nitrogen, argon, and oxygen. In this embodiment, the helium is separated from the raw material gas in the helium removal section 11 described later. The removed separated gas is supplied as a rinse gas to the first adsorption unit 7 through the rinse gas supply line 105. The separated gas separated and removed from the raw material gas in the helium removal unit 11 is mainly composed of helium. Therefore, by using this separated gas as a rinse gas, the regeneration process of the first adsorption unit 7 can be performed while suppressing the loss of neon. In addition, if necessary, a part of the raw material gas from which nitrogen, argon, and oxygen have been removed in the first adsorption unit 7, or a gas not containing nitrogen, argon, and oxygen that is supplied from outside the system of the neon purification apparatus 100 can also be supplied as a rinse gas to the first adsorption unit 7.

[0035] As described above, the desorbed gas such as nitrogen desorbed from the adsorbent in the first adsorption unit 7 in the regeneration step is mixed with the rinse gas supplied to the first adsorption unit 7 and discharged as a mixed gas from the first adsorption unit 7. The mixed gas may include a blowdown gas discharged from the adsorption tower in the depressurization step. Specifically, the mixed gas is discharged from the first adsorption unit 7 through the exhaust line 106. At least a portion of the mixed gas discharged from the first adsorption unit 7 through the exhaust line 106 may be supplied to the buffer container 1 as a reflux gas to improve the recovery rate of neon. Furthermore, the mixed gas discharged from the first adsorption unit 7 through the exhaust line 106 may be entirely discharged outside the system of the neon purification apparatus 100.

[0036] As shown in FIG. 1, the neon purification apparatus 100 includes a cold box 20. Some of the components constituting the neon purification apparatus 100 are disposed in the cold box 20. The inside of the cold box 20 is cooled by a circulating refrigerant supplied from a cryogenic refrigerator 21 to the first heat exchanger 8 and the second heat exchanger 10 in the cold box 20. Therefore, the components disposed in the cold box 20 are maintained at a lower temperature than the components disposed outside the cold box 20. Specifically, in the neon purification apparatus 100 of this embodiment, the first heat exchanger 8, the second adsorption section 9, the second heat exchanger 10, the helium removal section 11, the expansion valve 12, the distillation column 13, and the reboiler 14 are disposed in the cold box 20, and are maintained at a lower temperature than the buffer vessel 1, the compressor 2, the hydrogen oxidation section 3, the cooler 4, the normal temperature gas-liquid separator 5, the moisture removal section 6, and the first adsorption section 7, which are not disposed in the cold box 20.

[0037] The raw gas from which most of the nitrogen has been removed by the first adsorption section 7 is introduced into the first heat exchanger 8 as a cooling section in the cold box 20. The raw gas is introduced into the first heat exchanger 8 as a warm fluid, and is cooled by the first heat exchanger 8 to a temperature between 44K and 100K, for example. In this specification, in order to distinguish between the raw gas before being introduced into the first heat exchanger 8 as a cooling section and the raw gas after being cooled by the first heat exchanger 8 as a cooling section, the raw gas after being cooled by the first heat exchanger 8 as a cooling section may be referred to as a "cooled gas". The neon purification device 100 of this embodiment is equipped with a cryogenic refrigerator 21. A circulating refrigerant is supplied from the cryogenic refrigerator 21 to the first heat exchanger 8. The cryogenic refrigerator 21 may be, but is not limited to, a Brayton cycle. As the circulating refrigerant, for example, helium, neon, hydrogen, or a gas mixture of a plurality of these may be used.

[0038] The raw gas, which is a cooling gas cooled by the first heat exchanger 8, is introduced into the second adsorption section 9. The second adsorption section 9 includes an adsorbent and adsorbs and removes one or both of the nitrogen and argon that were not removed by the first adsorption section 7 from the raw gas, which is a cooling gas. If the raw gas introduced into the second adsorption section 9 contains oxygen, the oxygen may be adsorbed and removed by the second adsorption section 9. Examples of the adsorbent included in the second adsorption section 9 include zeolite and activated carbon, but are not limited to these. The second adsorption section 9 may be designed so that its performance can be maintained by performing a regeneration process when the entire device is returned to room temperature during regular inspection, etc. In addition, the second adsorption section 9 may be provided in multiple parts. The concentrations of nitrogen, argon, and oxygen in the raw gas discharged from the second adsorption section 9 may be set according to the purity required for the product neon, but are preferably 100 vol ppb or less.

[0039] The raw gas from which either or both of nitrogen and argon have been removed in the second adsorption section 9 is introduced into the second heat exchanger 10. The raw gas is introduced into the second heat exchanger 10 as a warm fluid, and is cooled by the second heat exchanger 10 to a temperature between 25K and 44K, for example. A circulating refrigerant from the cryogenic refrigerator 21 is supplied to the second heat exchanger 10 via the first heat exchanger 8. Note that FIG. 1 illustrates a form in which the circulating refrigerant of the cryogenic refrigerator 21 circulates through the first heat exchanger 8 and the second heat exchanger 10 connected in series to the cryogenic refrigerator 21. However, the circulating refrigerant of the cryogenic refrigerator 21 may circulate through the first heat exchanger 8 and the second heat exchanger 10 connected in parallel to the cryogenic refrigerator 21. Also, a refrigerator may be provided separately for each of the first heat exchanger 8 and the second heat exchanger 10.

[0040] The raw material gas cooled in the second heat exchanger 10 is introduced into the helium removal section 11. The helium removal section 11 removes helium from the raw material gas. Specifically, the helium removal section 11 in this embodiment is a low-temperature gas-liquid separator that separates the raw material gas into a separation liquid containing neon as a main component and a separation gas containing helium as a main component. The separation gas separated and removed from the raw material gas in the helium removal section 11 is supplied to the first adsorption section 7 as a rinse gas through a rinse gas supply line 105.

[0041] The separated liquid, which is mainly composed of neon and separated in the helium removal section 11, is introduced into the expansion valve 12. This separated liquid is decompressed by Joule-Thomson expansion by the expansion valve 12, and then introduced into the top side of the distillation column 13. In the distillation column 13, helium is further removed from the raw gas from which the separated gas mainly composed of helium has been separated and removed in the helium removal section 11, i.e., the above-mentioned separated liquid. Specifically, when the raw gas is supplied to the distillation column 13, neon gas containing helium is concentrated on the top side, and high-purity neon of 99 vol% or more is concentrated on the bottom side. This high-purity neon is extracted from the bottom side of the distillation column 13, compressed by the compressor 15, and extracted as product neon. Note that, when the product neon is extracted as a liquid from the distillation column 13, a liquid delivery pump may be used instead of the compressor 15. Also, the product neon may be extracted without using the compressor 15. The distillation column 13 is equipped with a reboiler 14 that vaporizes the descending liquid to produce an ascending gas. The distillation column 13 may be any of a structured packed column, a random packed column, and a plate column. The heating method of the reboiler 14 includes, but is not limited to, a heating method using an electric heater and a heating method using another warm fluid via a heat exchanger. Although not shown in FIG. 1, the distillation column 13 may be provided with a condenser that cools the ascending gas to produce a descending liquid. In addition, the neon purification apparatus 100 of this embodiment includes a distillation column gas reflux line 107 that can introduce the helium-containing distillation column gas discharged from the top of the distillation column 13 into the buffer container 1. This distillation column gas contains 80 vol% or more of neon, so the recovery rate of neon can be improved by refluxing the distillation column gas.

[0042] Next, a neon purification method using neon purification apparatus 100 will be described as one embodiment of the neon purification method according to the present invention. According to the neon purification method using neon purification apparatus 100, argon can be removed from the raw material gas by first adsorption unit 7 before cooling gas is supplied to second adsorption unit 9. This makes it possible to reduce the amount of argon in the cooling gas supplied to second adsorption unit 9, and suppress an increase in the operating power of cryogenic refrigerator 21. As a result, the efficiency of refining neon can be improved. EXAMPLES

[0043] An embodiment using the neon purification apparatus according to the present invention will be described below.

[0044] [Table 1]

[0045] <Example 1> In Example 1, neon was purified using a neon purification apparatus 100 shown in Figure 1. First, crude neon gas was supplied to a buffer container 1 through a crude neon gas supply line 101. The specifications of the crude neon gas were as shown in Table 1.

[0046] Next, the raw gas in the buffer vessel 1 was introduced into the compressor 2. The raw gas was compressed to 30 bar in the compressor 2. 0.1 Nm 3Oxygen gas was added at a flow rate of 100000 / h. The raw gas to which oxygen gas had been added was then supplied to the hydrogen oxidation section 3. The hydrogen oxidation section 3 was heated by an external heater. The hydrogen and oxygen in the raw gas were reacted with each other in the hydrogen oxidation section 3 to convert the hydrogen and oxygen into water. The raw gas discharged from the hydrogen oxidation section 3 passed through a cooler 4 and was then introduced into the room temperature gas-liquid separator 5. The room temperature gas-liquid separator 5 removed most of the moisture from the raw gas. The raw gas from which the moisture had been removed in the room temperature gas-liquid separator 5 was introduced into the moisture removal section 6. The moisture removal section 6 reduced the moisture and carbon dioxide concentrations in the raw gas to less than 10 volppb. The moisture removal section 6 was a two-tower TSA system, and while an adsorption process was being performed in one adsorption tower, a regeneration process was being performed in the other adsorption tower. The adsorption process and the regeneration process were performed by switching between the two adsorption towers alternately. Each adsorption tower was filled with zeolite. Dry nitrogen gas is supplied from outside the neon purification apparatus 100 through a dry gas supply line 103 at a flow rate of 1.5 Nm3 as a regeneration gas for the moisture removal unit 6. 3 / h to the moisture removal section 6. Specifically, this regeneration gas was introduced into the adsorption tower of the moisture removal section 6 in a state where it was heated to 200°C.

[0047] The raw gas from which moisture was removed in the moisture removal section 6 had a nitrogen concentration of 25 vol%, an argon concentration of 100 volppm, and an oxygen concentration of 10 volppm. This raw gas was introduced into the first adsorption section 7. The first adsorption section 7 was a four-tower VPSA type, and while an adsorption step was being performed in one adsorption tower, a regeneration step was performed in another adsorption tower, and a pressure equalization step was performed in the remaining two adsorption towers (only two towers are shown in FIG. 1, but in Example 1, a four-tower type was used). Each adsorption tower was filled with zeolite as an adsorbent. In Example 1, the pressure was reduced to 10 bar by two pressure equalization steps, and then depressurization was performed, and evacuation was performed to 0.05 bar in the evacuation step. The gas discharged in the depressurization step and evacuation step at this time was discharged outside the system of the neon purification apparatus 100. In the evacuation regeneration step, a separated gas mainly composed of helium separated and removed from the raw gas in the helium removal section 11 was supplied through the rinse gas supply line 105 to a rinsing gas supply line 105. The rinsing gas supply line 105 was used to supply the separated gas, mainly composed of helium, to a rinsing gas supply line 105. 3 / h as a rinse gas. A mixed gas consisting of the rinse gas supplied to the first adsorption section 7 and the desorbed gas such as nitrogen desorbed from the first adsorption section 7 was discharged outside the system via an exhaust line 106.

[0048] After nitrogen, argon and oxygen were adsorbed and removed in the first adsorption section 7, the concentrations of nitrogen, argon and oxygen in the raw material gas were each 10 volppm or less. The raw gas was introduced into the first heat exchanger 8 in the box 20. Next, the raw gas cooled to 68K in the first heat exchanger 8 was introduced into the second adsorption section 9. The concentrations of nitrogen, argon and oxygen in the raw gas after nitrogen, argon and oxygen were adsorbed and removed in the second adsorption section 9 were each less than 10 volppb. This second adsorption section 9 was filled with zeolite. The packed volume of zeolite required to continuously remove nitrogen, argon and oxygen for one year is 20L. After one year of continuous operation, the second adsorption section 9 is heated to room temperature, and a gas not containing nitrogen, argon and oxygen is circulated through the second adsorption section 9 to desorb nitrogen, argon and oxygen from the second adsorption section 9. Thereafter, the second adsorption section 9 is cooled, so that the second adsorption section 9 can again remove nitrogen, argon and oxygen in the same manner.

[0049] Next, the raw gas from which nitrogen, argon and oxygen were adsorbed and removed in the second adsorption section 9 was introduced into the second heat exchanger 10. Next, the raw gas cooled to 31K in the second heat exchanger 10 was introduced into the helium removal section 11. The separated gas separated and removed from the raw gas in the helium removal section 11 is composed of neon and helium, and contains 85 vol% or more of helium. As described above, this separated gas was supplied to the first adsorption section 7 as a rinse gas through the rinse gas supply line 105. Next, the liquefied gas on the liquid phase side of the helium removal section 11 was reduced in pressure to 3 bar by the expansion valve 12, and then introduced into the top side of the distillation column 13. Neon and helium in the raw gas were distilled and separated by gas-liquid contact in the distillation column 13. The distillation column 13 is a packed column filled with random packing. The distillation column 13 is equipped with a reboiler 14. The reboiler 14 is an electric heater type. The overhead gas of the distillation column 13 contained neon, and was refluxed to the buffer container 1 through the distillation column gas reflux line 107. Neon was concentrated in the bottom of the distillation column 13. This concentrated neon was extracted as product neon via compressor 15. The neon concentration of the product neon was 99.99 vol% or more. The flow rate of the product neon was 4.1 Nm 3 / h.

[0050] The neon refining apparatus 100 includes a cryogenic refrigerator 21 as a cold source. This cryogenic refrigerator 21 supplied a circulating refrigerant to the first heat exchanger 8 and the second heat exchanger 10. A Brayton cycle type was adopted for the cryogenic refrigerator 21. A turbo compressor was adopted as the circulation compressor for the circulating refrigerant. Helium gas was used as the circulating refrigerant. The operating power of the cryogenic refrigerator 21 in Example 1 was 22 kW.

[0051] <Comparative Example 1> In Comparative Example 1, neon was purified using the neon purification apparatus 100 shown in Fig. 1, as in Example 1. Comparative Example 1 differs from Example 1 in that the first adsorption section 7 was operated under operating conditions that removed only nitrogen from the raw material gas, but the other conditions and procedures are the same. Therefore, the differences from Example 1 will be mainly described here.

[0052] As described above, in Comparative Example 1, the first adsorption section 7 was operated under operating conditions for removing only nitrogen from the raw material gas. As a result, the nitrogen concentration in the raw material gas that passed through the first adsorption section 7 was 10 volppm or less, the argon concentration was 100 volppm, and the oxygen concentration was 10 volppm. In addition, the operating power of the cryogenic refrigerator 21 in Comparative Example 1 was 23 kW.

[0053] By comparing Example 1 with Comparative Example 1, it was confirmed that by removing argon and oxygen in addition to nitrogen in the first adsorption section 7, the operating power of the cryogenic refrigerator 21 can be reduced and the efficiency of refining neon can be improved.

[0054] The neon purification device and neon purification method of the present invention are not limited to the specific configurations and processes shown in the above-mentioned embodiments and examples, and various modifications, changes, substitutions, and combinations are possible without departing from the scope of the claims. [Industrial Applicability]

[0055] The present invention relates to a neon purification apparatus and method. [Explanation of symbols]

[0056] 1: Buffer container 2: Compressor 3: Hydrogen oxidation section 4:Cooler 5: Normal temperature gas-liquid separator 6: Moisture removal section 7: 1st suction part 8: 1st heat exchanger 9:Second suction part 10:Second heat exchanger 11: Helium removal section 12: Expansion valve 13: Distillation tower 14: Reboiler 15: Compressor 20: Cold box 21: Cryogenic refrigerator 100: Neon Refining Device 101: Crude neon gas supply line 103: Dry gas supply line 104: Exhaust line 105: Rinse gas supply line 106: Exhaust line 107: Distillation tower gas reflux line

Claims

1. a first adsorption section that adsorbs and removes nitrogen and argon from the source gas; a cooling section for cooling the raw material gas from which nitrogen and argon have been adsorbed and removed in the first adsorption section to produce a cooled gas; a second adsorption section that adsorbs and removes one or both of nitrogen and argon from the cooling gas.

2. 2. The neon purification apparatus according to claim 1, wherein an amount of argon adsorbed and removed from the source gas by the first adsorption section is greater than an amount of argon adsorbed and removed from the cooling gas by the second adsorption section.

3. 3. The neon purification apparatus according to claim 1, wherein the concentration of argon in the raw gas after nitrogen and argon are adsorbed and removed in the first adsorption section is 10 vol ppm or less.

4. 3. The neon purification apparatus according to claim 1, wherein oxygen gas containing argon is added to the raw material gas before the raw material gas is supplied to the first adsorption section.

5. A method for refining neon using the neon refining apparatus according to claim 1 or 2.

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