Neon refining apparatus and method

Abstract

Provided are a neon purification device and a neon purification method capable of efficiently purifying neon from a gas containing neon, nitrogen, and helium. [Solution] The neon purification apparatus of the present invention comprises an adsorption section that adsorbs and removes nitrogen from a mixed gas containing neon, helium and nitrogen, a separation section that separates and removes helium from the nitrogen-removed gas from which nitrogen has been adsorbed and removed in the adsorption section, and a regeneration gas introduction line that can introduce a separated gas containing helium separated and removed in the separation section into the adsorption section as a regeneration gas that regenerates the adsorption capacity of the adsorption section.

Description

[Technical field]

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

[0002] Neon is contained in air at approximately 18 ppm, and is used as the main component of discharge tube gas and mixed gas for excimer laser oscillation. When air is liquefied and distilled to produce oxygen, nitrogen, and argon, neon is discharged from the rectification column as an uncondensed gas together with nitrogen, helium, hydrogen, etc. Patent documents 1 and 2 describe methods for purifying neon from mixed gas containing neon, nitrogen, helium, and hydrogen.

[0003] Patent Document 1 describes a process in which neon is refined as liquefied neon using a section for oxidizing hydrogen, etc., a section for removing moisture, etc., a section for liquefying and removing nitrogen at low temperatures, a section for removing residual nitrogen, etc. by low-temperature adsorption, and a fractionator.

[0004] US Pat. No. 5,399,633 describes a nitrogen removal section and a process for separating helium, neon and hydrogen by cryogenic adsorption. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] U.S. Pat. No. 1,076,7923 [Patent Document 2] Patent No. 3268177 Summary of the Invention [Problem to be solved by the invention]

[0006] In the process of Patent Document 1, in order to purify neon from a mixed gas containing at least neon, nitrogen, and helium, nitrogen and the like are removed by low-temperature adsorption. Therefore, it is necessary to regenerate the adsorbent by a temperature swing method, in which the adsorption tower is heated to desorb the adsorbed components from the adsorbent. In this case, it is necessary to use the gas purified by low-temperature adsorption as the regeneration gas in order to promote the desorption of the adsorbed components from the adsorbent. However, when the regeneration gas flow rate is low, it takes time to heat the adsorption tower and desorb the adsorbed components, so the device becomes large, and when the regeneration gas flow rate is high, a lot of the gas purified by low-temperature adsorption is consumed, resulting in a reduction in the product discharge flow rate.

[0007] In the process of Patent Document 2, in order to purify neon from a mixed gas containing hydrogen, neon, nitrogen, and helium, a purified gas containing neon from which nitrogen gas has been removed is used as a regeneration gas that promotes desorption of the components adsorbed on the adsorbent in the nitrogen removal tower. As a result, the product discharge flow rate is reduced, and desorption of the components adsorbed on the adsorbent requires 10 -3 It is not an optimized process for purifying neon, as it requires a vacuum of up to Torr.

[0008] An object of the present invention is to provide a neon purification apparatus and a neon purification method capable of efficiently purifying neon from a gas containing neon, nitrogen, and helium. [Means for solving the problem]

[0009] A neon purification apparatus according to a first aspect of the present invention comprises: (1) an adsorption section that adsorbs and removes nitrogen from a mixed gas containing neon, helium, and nitrogen; a separation section that separates and removes helium from the nitrogen-removed gas from which nitrogen has been adsorbed and removed in the adsorption section; a regeneration gas introduction line capable of introducing a separated gas containing helium separated and removed in the separation section into the adsorption section as a regeneration gas for regenerating the adsorption capacity of the adsorption section.

[0010] As one embodiment of the present invention, a neon purification apparatus includes: (2) a buffer container in which a source gas serving as a source of the mixed gas is stored; and a used gas reflux line capable of introducing into the buffer container a mixed used gas of the regeneration gas and a desorbed gas containing nitrogen desorbed from the adsorption section as a result of the regeneration gas being introduced into the adsorption section.

[0011] As one embodiment of the present invention, a neon purification apparatus includes: (3) a distillation column for further separating and removing helium from the helium-removed gas from which helium has been separated and removed in the separation section; and a distillation column gas reflux line capable of introducing a distillation column gas containing helium separated and removed in the distillation column into the buffer container.

[0012] As one embodiment of the present invention, a neon purification apparatus includes: (4) The neon purification apparatus according to claim 2 or 3, further comprising a heat exchanger capable of cooling the mixed gas before it is introduced into the adsorption section.

[0013] As one embodiment of the present invention, a neon purification apparatus includes: (5) a preliminary separation section for separating and removing nitrogen from the mixed gas before the mixed gas is introduced into the adsorption section; and a pre-separation gas reflux line capable of introducing a pre-separation gas containing nitrogen separated and removed in the pre-separation section into the buffer container.

[0014] As one embodiment of the present invention, a neon purification apparatus includes: (6) The neon purification apparatus according to any one of (1) to (5) above, further comprising a guard absorber that further removes nitrogen from the nitrogen-removing gas before the nitrogen-removing gas is introduced into the separation section.

[0015] A neon purification method according to a second aspect of the present invention includes the steps of: (7) A neon purification method using the neon purification device according to any one of (1) to (6) above. Effect of the Invention

[0016] According to the present invention, it is possible to provide a neon purification device and a neon purification method capable of efficiently purifying neon from a gas containing neon, nitrogen, and helium. [Brief description of the drawings]

[0017] [Figure 1] FIG. 1 illustrates a neon purification device according to a first embodiment of the present invention. [Diagram 2] FIG. 2 shows a neon purification apparatus according to a second embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of a neon purification apparatus and a neon purification method according to the present invention will be described with reference to the drawings. In each drawing, the same components are designated by the same reference numerals.

[0019] First Embodiment 1 is a diagram showing a neon refiner 100 as a first embodiment of the neon refiner according to the present invention. The configuration of neon refiner 100 and a neon refinement method using neon refiner 100 will be described below.

[0020] Crude neon gas supply line 1 is a line that supplies crude neon gas to buffer vessel 2. The crude neon gas mainly consists of 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.

[0021] The buffer container 2 is capable of receiving the crude neon gas from the crude neon gas supply line 1 and the reflux gas that is refluxed as part of the process of the neon purification apparatus 100, and storing and holding them as raw material gas. Here, the raw material gas means the gas stored in the buffer container 2, and specifically refers to the crude neon gas or a gas obtained by mixing the crude neon gas and the reflux gas from the neon purification apparatus 100. Examples of the reflux gas include, but are not limited to, the reflux gas from the preliminary separation section 109 described below, the reflux gas from the adsorption section 112 described below, and the reflux gas from the distillation column 18 described below. The material of the buffer container 2 may be either metal or resin.

[0022] The neon purification apparatus 100 of this embodiment includes a mixed gas introduction line 102 that connects the buffer vessel 2 with the adsorption section 112 described below. The mixed gas introduction line 102 of this embodiment is provided with a compressor 3, a hydrogen oxidation tower 4, a cooler 5, a gas-liquid separator 6, a moisture removal tower 7, a heat exchanger 8, and a gas-liquid separator 9. However, the configuration of the mixed gas introduction line 102 is not limited thereto. Hereinafter, for the sake of convenience, the gas introduced into the adsorption section 112 through the mixed gas introduction line 102 may be collectively referred to as a "mixed gas containing neon, helium, and nitrogen" or simply as a "mixed gas." In other words, the raw material gas in the buffer vessel 2 is a gas that serves as a raw material for the mixed gas.

[0023] The compressor 3 can pressurize the raw gas to a pressure required for the process. The raw gas pressurized by the compressor 3 is supplied to the hydrogen oxidation tower 4. The hydrogen oxidation tower 4 is filled with a catalyst. The raw gas introduced into the hydrogen oxidation tower 4 may be heated, for example, by heating the hydrogen oxidation tower 4 from the outside. The raw gas introduced into the hydrogen oxidation tower 4 may also be heated, for example, by a heating unit provided in the hydrogen oxidation tower 4. By adding oxygen gas to the raw gas before being introduced into the hydrogen oxidation tower 4, the hydrogen and oxygen in the raw gas are heated and reacted in the hydrogen oxidation tower 4 to be converted into water. Examples of catalysts include platinum, palladium, copper, etc., but are not limited to these. The raw gas discharged from the hydrogen oxidation tower 4 passes through a cooler 5, and the raw gas heated in the hydrogen oxidation tower 4 is cooled to below room temperature. The cooled raw gas is introduced into a gas-liquid separator 6. The gas introduced into the gas-liquid separator 6 is separated into the gas-liquid separator 6, with the water condensed by cooling being on the liquid phase side and the rest being on the gas phase side.

[0024] The gas containing neon on the gas phase side of the gas-liquid separator 6 is introduced into the moisture removal tower 7. The moisture removal tower 7 repeats adsorption and desorption by temperature swing. The moisture removal tower 7 is filled with a desiccant. This desiccant removes moisture and CO2 by adsorption. Examples of desiccant include, but are not limited to, molecular sieves, silica gel, and activated alumina. The moisture removal tower 7 is mainly composed of at least two towers, and during operation of the device, an adsorption process is performed in one tower and a regeneration process is performed in another tower. During regeneration, the tower is heated by an external heater or heated nitrogen gas, etc., to remove the adsorbed moisture and CO2. The blowdown gas generated when switching between the adsorption process and the regeneration process may be collected as a reflux gas in the buffer container 2. By collecting the blowdown gas as a reflux gas, the yield of the product neon relative to the total amount of raw gas can be improved.

[0025] The mixed gas containing neon, helium and nitrogen from which moisture and CO2 have been removed by the moisture removal tower 7 is introduced into the heat exchanger 8 in the cold box 22. In this heat exchanger 8, the mixed gas is introduced as a hot fluid and cooled to a temperature between 65K and 100K, for example. In addition, a liquefied gas containing nitrogen as a main component separated in a process in the gas-liquid separator 11 described later is also introduced into the heat exchanger 8 as a cold fluid. Furthermore, the neon purification device 100 of this embodiment is equipped with a cryogenic refrigerator 21, and a circulating refrigerant is supplied from the cryogenic refrigerator 21 to the heat exchanger 8. The cryogenic refrigerator 21 may be a Brayton cycle type, but is not limited to this. Helium, neon, hydrogen, or a mixture of these gases may be used as the circulating refrigerant.

[0026] The mixed gas containing neon, helium and nitrogen cooled by the heat exchanger 8 is introduced into the preliminary separation section 109. The preliminary separation section 109 can separate and remove nitrogen from the mixed gas before the mixed gas is introduced into the adsorption section 112 described later. More specifically, the preliminary separation section 109 of this embodiment is a gas-liquid separator 9 capable of separating a liquefied gas containing nitrogen as a main component into a liquid phase side and a gas containing neon as a main component into a gas phase side. The neon purification device 100 of this embodiment also includes a preliminary separation gas reflux line 309 capable of introducing the preliminary separation gas containing nitrogen separated and removed in the preliminary separation section 109 into the buffer container 2. More specifically, the preliminary separation gas reflux line 309 is a line connecting the gas-liquid separator 9 and the buffer container 2. The preliminary separation gas reflux line 309 of this embodiment is provided with an expansion valve 10 and a gas-liquid separator 11. The liquefied gas, the main component of which is nitrogen, separated and removed in the gas-liquid separator 9 is sent to the expansion valve 10, where it is decompressed by Joule-Thomson expansion and introduced into the gas-liquid separator 11. In the gas-liquid separator 11, the liquefied gas containing 95% or more nitrogen is separated into the liquid phase and the gas in which neon and helium are concentrated is separated into the gas phase. As described above, the liquefied gas containing 95% or more nitrogen is introduced as a cold fluid into the heat exchanger 8, where it is vaporized and released into the atmosphere, and is then exhausted. The gas on the gas phase side of the gas-liquid separator 11 is returned to the buffer vessel 2 via the pre-separated gas return line 309. This makes it possible to improve the yield of the product neon relative to the total amount of the raw gas.

[0027] The mixed gas containing neon, helium and nitrogen on the gas phase side of the gas-liquid separator 9 is introduced into the adsorption section 112. The adsorption section 112 adsorbs and removes nitrogen from the mixed gas. More specifically, the adsorption section 112 of this embodiment is a low-temperature adsorber 12 of a temperature swing type (TSA) that repeats adsorption and desorption by temperature swing. However, the low-temperature adsorber 12 may be a pressure swing type (PSA) or a pressure swing type (VPSA) using a vacuum pump. The low-temperature adsorber 12 is filled with an adsorbent, and can remove nitrogen from a mixed gas containing neon as a main component at a temperature between 65K and 100K. Examples of the adsorbent include, but are not limited to, molecular sieves and activated carbon. The low-temperature adsorber 12 is mainly composed of at least two or more towers, and during operation of the device, an adsorption process is performed in one tower and a regeneration process is performed in another tower.

[0028] The neon purification apparatus 100 of this embodiment includes a regeneration gas introduction line 16 that can introduce the separated gas containing helium separated and removed in the separation section 115 described later into the adsorption section 112 as a regeneration gas for regenerating the adsorption capacity of the adsorption section 112. More specifically, the regeneration gas introduction line 16 of this embodiment is a line that connects the gas-liquid separator 15 as the separation section 115 described later and the low-temperature adsorber 12 as the adsorption section 112. By providing such a regeneration gas introduction line 16, the gas phase gas of the gas-liquid separator 15 can be used as the regeneration gas for the low-temperature adsorber 12. Normally, the outlet purified gas of the low-temperature adsorber 12 is used as the regeneration gas, but the regeneration gas needs to be returned to the buffer vessel 2 to reduce the loss of neon, and in that case, the amount of circulated process gas increases. As a result, the load of the cryogenic refrigerator 21 that generates cold is increased, and the power required for producing high-purity neon increases. On the other hand, in this embodiment, the gas phase gas of the gas-liquid separator 15 is used as the regeneration gas via the regeneration gas introduction line 16. Due to the mass balance of the process, this gas phase gas needs to be exhausted, and even if it is used as a regeneration gas, it does not increase the loss of neon. Therefore, it is possible to reduce the power required for producing high purity neon while maintaining the neon yield and without increasing the process gas flow rate. In other words, neon can be efficiently purified from a gas containing neon, nitrogen, and helium. Note that a heater 13 is provided in the regeneration gas inlet line 16 that introduces the regeneration gas into the low-temperature adsorber 12, and the regeneration gas can be heated during thermal regeneration. An external heater may be provided in the adsorption section 112.

[0029] In this embodiment, the adsorption section 112 is connected to a discharge line 312 capable of discharging the blowdown gas of the adsorption section 112, and the spent gas in a mixed state of the regeneration gas and the desorbed gas containing nitrogen desorbed from the adsorption section 112 by introducing the regeneration gas into the adsorption section 112, to the outside of the neon purification apparatus 100. A used gas reflux line 313 may be connected to this discharge line 312 as a branch line. The used gas reflux line 313 is a line that connects the adsorption section 112 and the buffer container 2. By providing such a used gas reflux line 313, it is possible to introduce the blowdown gas or the used gas into the buffer container 2 as a reflux gas. In other words, by providing such a used gas reflux line 313, it is possible to improve the yield of the product neon relative to the total amount of the raw material gas.

[0030] Neon purification apparatus 100 of the present embodiment includes a nitrogen removal gas introduction line 315 that connects adsorption section 112 and separation section 115, which will be described later. Nitrogen removal gas introduction line 315 of the present embodiment is provided with a heat exchanger 14. However, the configuration of nitrogen removal gas introduction line 315 is not limited to this. Hereinafter, for ease of explanation, the gas introduced into separation section 115 via nitrogen removal gas introduction line 315 may be collectively referred to as "nitrogen removal gas from which nitrogen has been adsorbed and removed in adsorption section 112" or simply as "nitrogen removal gas."

[0031] The outlet purified gas (nitrogen-removed gas) of the low-temperature adsorber 12 is introduced into the heat exchanger 14. In this heat exchanger 14, the nitrogen-removed gas containing neon and helium is introduced as a warm fluid and cooled to a temperature between 25 K and 65 K, for example. A circulating refrigerant from the cryogenic refrigerator 21 is supplied to the heat exchanger 14 via the heat exchanger 8. Note that, although FIG. 1 illustrates a configuration in which the circulating refrigerant of the cryogenic refrigerator 21 circulates through the heat exchanger 14 and the heat exchanger 8 connected in series to the cryogenic refrigerator 21, the circulating refrigerant of the cryogenic refrigerator 21 may also be circulated through the heat exchanger 14 and the heat exchanger 8 connected in parallel to the cryogenic refrigerator 21. Also, a refrigerator may be provided separately for each of the heat exchanger 14 and the heat exchanger 8.

[0032] The nitrogen-removed gas cooled by the heat exchanger 14 is introduced into the separation section 115. The separation section 115 separates and removes helium from the nitrogen-removed gas. More specifically, the separation section 115 in this embodiment is a gas-liquid separator 15 capable of separating from the nitrogen-removed gas a liquefied gas mainly composed of neon into a liquid phase side and a gas mainly composed of helium into a gas phase side. As described above, the gas phase gas from the gas-liquid separator 15 is used as a regeneration gas for the low-temperature adsorber 12 via the regeneration gas introduction line 16.

[0033] The liquefied gas on the liquid phase side of the gas-liquid separator 15 is mainly composed of neon, and this liquefied gas is introduced into the expansion valve 17. This liquefied gas is reduced in pressure by Joule-Thomson expansion in the expansion valve 17, and introduced into the top side of the distillation column 18. The distillation column 18 further separates and removes helium from the helium-removed gas from which helium has been separated and removed in the separation section 115. More specifically, the distillation column 18 is capable of distilling and separating neon and helium. In the distillation column 18, neon gas containing helium is concentrated on the top side, and high-purity neon of 99% or more is concentrated on the bottom side. The neon extracted from the bottom side of the distillation column 18 is compressed by the compressor 20 and taken out as product neon. When the product neon is collected in liquid form, a liquid pump may be used instead of the compressor 20. When it is not necessary to compress the product, the product neon may be taken out without using the compressor 20. The distillation tower 18 is provided with a reboiler 19 having a function of vaporizing the descending liquid to produce an ascending gas. The distillation tower 18 may be a structured packed tower, a random packed tower, or a plate tower. The heating method of the reboiler 19 may include, but is not limited to, a heating method using an electric heater or a heating method using another warm fluid via a heat exchanger. Although not shown in FIG. 1, the distillation tower 18 may be provided with a condenser that cools the ascending gas to produce a descending liquid. The neon purification apparatus 100 of this embodiment is provided with a distillation tower gas reflux line 318 that can introduce the distillation tower gas containing helium separated and removed in the distillation tower 18 into the buffer container 2. More specifically, the distillation tower gas reflux line 318 is a line that connects the top of the distillation tower 18 to the buffer container 2. By providing such a distillation tower gas reflux line 318, the distillation tower gas containing helium concentrated on the top side of the distillation tower 18 can be introduced into the buffer container 2 as a reflux gas via the distillation tower gas reflux line 318. As a result, the yield of the product neon relative to the total amount of the feed gas can be improved.

[0034] <Second embodiment> 2 is a diagram showing a neon refiner 200 as a second embodiment of the neon refiner according to the present invention. The configuration of neon refiner 200 and a neon refinement method using neon refiner 200 will be described below.

[0035] The crude neon gas supply line 31 is a line that supplies the crude neon gas to the buffer container 32. The crude neon gas mainly consists of 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.

[0036] Buffer container 32 is capable of receiving crude neon gas from crude neon gas supply line 31 and reflux gas that is refluxed as part of the process of neon purification apparatus 200, and storing and holding them as raw material gas. Here, raw material gas means the gas stored in buffer container 32, and specifically refers to crude neon gas or a mixture of crude neon gas and reflux gas from neon purification apparatus 200. Examples of reflux gas include, but are not limited to, reflux gas from adsorption section 138, which will be described later, and reflux gas from distillation column 46, which will be described later. The material of buffer container 32 may be either metal or resin.

[0037] The neon purification apparatus 200 of this embodiment includes a mixed gas introduction line 232 that connects the buffer vessel 32 with the adsorption section 138 described below. The mixed gas introduction line 232 of this embodiment is provided with a compressor 33, a hydrogen oxidation tower 34, a cooler 35, a gas-liquid separator 36, and a moisture removal tower 37. However, the configuration of the mixed gas introduction line 232 is not limited to this. Hereinafter, for convenience of explanation, the gas introduced into the adsorption section 138 through the mixed gas introduction line 232 may be collectively referred to as a "mixed gas containing neon, helium, and nitrogen" or simply as a "mixed gas." In other words, the raw material gas in the buffer vessel 32 is a gas that is a raw material for the mixed gas.

[0038] The compressor 33 can boost the raw gas to a pressure required for the process. The raw gas boosted by the compressor 33 is supplied to the hydrogen oxidation tower 34. The hydrogen oxidation tower 34 is filled with a catalyst. The raw gas introduced into the hydrogen oxidation tower 34 may be heated, for example, by heating the hydrogen oxidation tower 34 from the outside. The raw gas introduced into the hydrogen oxidation tower 34 may also be heated, for example, by a heating unit provided in the hydrogen oxidation tower 34. By adding oxygen gas to the raw gas before being introduced into the hydrogen oxidation tower 34, the hydrogen and oxygen in the raw gas are heated and reacted in the hydrogen oxidation tower 34 to be converted into water. Examples of catalysts include, but are not limited to, platinum, palladium, copper, and the like. The raw gas discharged from the hydrogen oxidation tower 34 passes through a cooler 35, and the gas heated in the hydrogen oxidation tower 34 is cooled to room temperature or below. The cooled raw gas is introduced into a gas-liquid separator 36. The gas introduced into the gas-liquid separator 36 is separated in the gas-liquid separator 36, where condensed water due to cooling is transferred to the liquid phase side, and the rest is transferred to the gas phase side.

[0039] The gas containing neon on the gas phase side of the gas-liquid separator 36 is introduced into the moisture removal tower 37. The moisture removal tower 37 repeats adsorption and desorption by temperature swing. The moisture removal tower 37 is filled with a desiccant. This desiccant removes moisture and CO2 by adsorption. Examples of desiccant include, but are not limited to, molecular sieves, silica gel, and activated alumina. The moisture removal tower 37 is composed of at least two towers, and during operation of the device, an adsorption process is performed in one tower and a regeneration process is performed in another tower. During regeneration, the tower is heated by an external heater or heated nitrogen gas, etc., to remove the adsorbed moisture and CO2. The blowdown gas generated when switching between the adsorption process and the regeneration process may be collected as a reflux gas in the buffer container 32. By collecting the blowdown gas as a reflux gas, the yield of the product neon relative to the total amount of the raw gas can be improved.

[0040] The mixed gas containing neon, helium and nitrogen from which moisture and CO2 have been removed by the moisture removal tower 37 is introduced into the adsorption section 138. The adsorption section 138 adsorbs and removes nitrogen from the mixed gas. The adsorption section 138 in this embodiment is a nitrogen adsorption tower 38 of a pressure swing type (VPSA) that repeats adsorption and desorption by pressure swing using a vacuum pump 39. However, the nitrogen adsorption tower 38 may be a temperature swing type (TSA) or a pressure swing type (PSA) that does not use a vacuum pump. The nitrogen adsorption tower 38 is filled with an adsorbent, which mainly removes nitrogen from the neon-containing gas by adsorption. Examples of the adsorbent include zeolite and activated carbon, but are not limited to these. The nitrogen adsorption tower 38 is composed of at least two or more towers, and is preferably composed of three or more towers in order to reduce the loss of neon in the nitrogen adsorption tower 38. A vacuum pump 39 is connected to each tower constituting the nitrogen adsorption tower 38. The vacuum pump 39 is used in the regeneration step of the nitrogen adsorption tower 38, and can desorb the adsorbed nitrogen by a pressure difference.

[0041] In this embodiment, the adsorption section 138 is connected to a discharge line 438 capable of discharging the blowdown gas of the adsorption section 138, and the spent gas in a mixed state of the regeneration gas and the desorbed gas containing nitrogen desorbed from the adsorption section 138 by introducing the regeneration gas into the adsorption section 138, to the outside of the neon purification apparatus 200. In this embodiment, the vacuum pump 39 is provided on this discharge line 438. A used gas reflux line 439 may be connected to this discharge line 438 as a branch line. The used gas reflux line 439 is a line that connects the adsorption section 138 and the buffer container 32. By providing such a used gas reflux line 439, it is possible to introduce the blowdown gas or the used gas into the buffer container 32 as a reflux gas. In other words, by providing such a used gas reflux line 439, it is possible to improve the yield of the product neon relative to the total amount of the raw material gas.

[0042] The neon purification apparatus 200 of this embodiment includes a regeneration gas introduction line 44 that can introduce the separated gas containing helium separated and removed in the separation section 143 described later into the adsorption section 138 as a regeneration gas for regenerating the adsorption capacity of the adsorption section 138. More specifically, the regeneration gas introduction line 44 of this embodiment is a line that connects a gas-liquid separator 43 as the separation section 143 described later and a nitrogen adsorption tower 38 as the adsorption section 138. By providing this regeneration gas introduction line 44, the gas phase gas of the gas-liquid separator 43 can be supplied to the nitrogen adsorption tower 38 as a regeneration gas via the regeneration gas introduction line 44. This can promote desorption of the nitrogen adsorbed in the adsorption section 138, and the nitrogen adsorption tower 38 as the adsorption section 138 can be designed to be small. As a result, the loss of neon can be reduced, and the manufacturing cost can be reduced. That is, neon can be efficiently purified from a gas containing neon, nitrogen, and helium. Note that if the regeneration gas is not used, the efficiency of desorption decreases, and the performance of the adsorption tower decreases, so it is necessary to increase the amount of adsorbent accordingly. Increasing the size of the adsorption tower to increase the amount of adsorbent results in a large loss of neon-containing gas. In addition, it is preferable that the gas that can be used as the regeneration gas does not contain nitrogen and does not contain any gas other than the crude neon gas component. Gases that meet this condition are helium gas or product neon gas. When the former, helium gas, is used, the production cost of high-purity neon (i.e., the cost of refining neon) increases by the amount of helium gas used, and when the latter, product neon gas, is used, the neon yield decreases, so the production cost of high-purity neon also increases.

[0043] The neon purification apparatus 200 of this embodiment includes a nitrogen removal gas introduction line 443 that connects the adsorption section 138 and a separation section 143 described below. The nitrogen removal gas introduction line 443 of this embodiment is provided with a heat exchanger 40, a guard absorber 41, and a heat exchanger 42. However, the configuration of the nitrogen removal gas introduction line 443 is not limited to this. Hereinafter, for ease of explanation, the gas introduced into the separation section 143 through the nitrogen removal gas introduction line 443 may be collectively referred to as the "nitrogen removal gas from which nitrogen has been adsorbed and removed in the adsorption section 138" or simply as the "nitrogen removal gas."

[0044] The neon-containing nitrogen-removed gas from which nitrogen has been adsorbed and removed in the adsorption section 138 is introduced into the heat exchanger 40 in the cold box 50. In this heat exchanger 40, the neon-containing gas is introduced as a warm fluid and cooled to a temperature between 44 K and 100 K, for example. The neon purification device of this embodiment is equipped with a cryogenic refrigerator 49, and a circulating refrigerant is supplied from the cryogenic refrigerator 49 to the heat exchanger 40. The cryogenic refrigerator 49 may be of a Brayton cycle type, but is not limited to this type. The circulating refrigerant may be helium, neon, hydrogen, or a mixture thereof.

[0045] The nitrogen-removed gas cooled by the heat exchanger 40 is introduced into the guard absorber 41. The guard absorber 41 can remove 10 to 100 ppm of nitrogen that cannot be completely removed by the adsorption section 138 from the nitrogen-removed gas. The guard absorber 41 is filled with an adsorbent, and can remove 10 to 100 ppm of nitrogen that cannot be completely removed by the adsorption section 138 from the nitrogen-removed gas at a temperature between 44 K and 100 K. Examples of the adsorbent include molecular sieves and activated carbon, but are not limited to these. The guard absorber 41 may be designed so that its performance is maintained by regenerating it when the entire device is returned to room temperature for periodic inspection, etc. Note that a plurality of guard absorbers 41 may be provided.

[0046] The outlet gas (nitrogen-removed gas) of the guard absorber 41 is introduced into the heat exchanger 42. In the heat exchanger 42, the nitrogen-removed gas containing neon and helium is introduced as a warm fluid and cooled to a temperature between 25K and 44K, for example. A circulating refrigerant from the cryogenic refrigerator 49 is supplied to the heat exchanger 42 via the heat exchanger 40. Note that, although FIG. 2 illustrates a configuration in which the circulating refrigerant of the cryogenic refrigerator 49 circulates through the heat exchanger 42 and the heat exchanger 40 connected in series to the cryogenic refrigerator 49, the circulating refrigerant of the cryogenic refrigerator 49 may circulate through the heat exchanger 42 and the heat exchanger 40 connected in parallel to the cryogenic refrigerator 49. Also, a refrigerator may be provided separately for each of the heat exchanger 42 and the heat exchanger 40.

[0047] The nitrogen-removed gas cooled by the heat exchanger 42 is introduced into the separation section 143. The separation section 143 separates and removes helium from the nitrogen-removed gas. More specifically, the separation section 143 in this embodiment is a gas-liquid separator 43 that can separate from the nitrogen-removed gas a liquefied gas mainly composed of neon into a liquid phase side and a gas mainly composed of helium into a gas phase side. As described above, the gas phase gas from the gas-liquid separator 43 is used as a regeneration gas for the nitrogen adsorption tower 38 via the regeneration gas introduction line 44.

[0048] The liquefied gas on the liquid phase side of the gas-liquid separator 43 is mainly composed of neon, and this liquefied gas is introduced into the expansion valve 45. This liquefied gas is reduced in pressure by Joule-Thomson expansion in the expansion valve 45, and introduced into the top side of the distillation column 46. The distillation column 46 further separates and removes helium from the helium-removed gas from which helium has been separated and removed in the separation section 143. More specifically, the distillation column 46 is capable of distilling and separating neon and helium by gas-liquid contact. In the distillation column 46, neon gas containing helium is concentrated on the top side, and high-purity neon of 99% or more is concentrated on the bottom side. The neon is extracted from the bottom side of the distillation column 46, compressed by the compressor 48, and taken out as product neon. When the product neon is collected in liquid form, a liquid pump may be used instead of the compressor 48. When it is not necessary to compress the product, the product neon may be taken out without using the compressor 48. The distillation tower 46 is provided with a reboiler 47 having a function of vaporizing the descending liquid to produce an ascending gas. The distillation tower 46 may be a structured packed tower, a random packed tower, or a plate tower. The heating method of the reboiler 47 may include, but is not limited to, a heating method using an electric heater or a heating method using another warm fluid via a heat exchanger. Although not shown in FIG. 2, the distillation tower 46 may be provided with a condenser for cooling the ascending gas to produce a descending liquid. The neon purification apparatus 200 of this embodiment is provided with a distillation tower gas reflux line 246 that can introduce the distillation tower gas containing helium separated and removed in the distillation tower 46 into the buffer container 32. More specifically, the distillation tower gas reflux line 246 is a line that connects the top of the distillation tower 46 to the buffer container 32. This allows the distillation tower gas concentrated on the top side of the distillation tower 46 to be introduced as reflux gas into the buffer container 32 via the distillation tower gas reflux line 246. As a result, the yield of the product neon relative to the total amount of the feed gas can be improved.

[0049] The neon purification device and neon purification method according to the present invention are not limited to the specific configurations shown in the above-described embodiments, and various modifications, changes, and combinations are possible without departing from the scope of the claims. EXAMPLES

[0050] An embodiment using the neon purification apparatus according to the present invention will be described below.

[0051] Example 1 In Example 1, high-purity neon was produced (neon was purified) using the neon purification apparatus 100 shown in FIG.

[0052] First, crude neon gas was supplied to a buffer container 2 through a crude neon gas supply line 1. The specifications of the crude neon gas were as shown in Table 1.

[0053] [Table 1]

[0054] Next, the raw gas in the buffer vessel 2 was introduced into the compressor 3. In the compressor 3, the raw gas was compressed to 30 bar. 3 Oxygen gas was added at a flow rate of 10000 kPa / h, and the mixture of raw gas and oxygen was sent to hydrogen oxidation tower 4. Hydrogen oxidation tower 4 was heated by an external heater, and the hydrogen and oxygen in the raw gas were reacted by a catalytic reaction to convert them into water. The outlet gas of hydrogen oxidation tower 4 passed through cooler 5 and was introduced into gas-liquid separator 6, where most of the moisture was removed. The gas on the gas phase side of gas-liquid separator 6 was introduced into moisture removal tower 7, where the moisture and CO2 in the gas were removed, and the respective concentrations became less than 10 ppb. The moisture removal tower 7 is a two-tower type, one of which is for the adsorption process and the other for the regeneration process. Each tower is filled with molecular sieves.

[0055] The neon-containing gas at the outlet of the moisture removal tower 7 was introduced into the heat exchanger 8 in the cold box 22. The neon-containing gas was cooled to 68K in the heat exchanger 8 and introduced into the gas-liquid separator 9. The nitrogen concentration in the gas phase gas in the gas-liquid separator 9 was 2%. The liquefied gas on the liquid phase side of the gas-liquid separator 9 was reduced in pressure to 1.5 bar via the expansion valve 10 and introduced into the gas-liquid separator 11. The nitrogen concentration in the liquefied gas on the liquid phase side of the gas-liquid separator 11 was 99% or more, and this liquefied gas was introduced into the heat exchanger 8 as a cold fluid. This liquefied gas was vaporized by heat exchange and then released outside the system. The gas phase gas in the gas-liquid separator 11 contained 80% or more neon, so it was refluxed to the buffer container 2.

[0056] The gas phase gas from the gas-liquid separator 9 is introduced into the low-temperature adsorber 12, and the nitrogen concentration in the neon-containing gas is less than 10 ppb. The low-temperature adsorber 12 is a two-tower type, with one tower being used for the adsorption process and the other being used for the regeneration process. Each adsorption tower is filled with activated carbon as an adsorbent. The regeneration process of the low-temperature adsorber 12 mainly consists of a heating process and a cooling process. In this embodiment 1, during the heating process, the gas phase gas from the gas-liquid separator 15 is introduced into the heater 13 via the regeneration gas introduction line 16, the gas is heated to 200 K by the heater 13, and the gas is introduced from the outlet side of the adsorption tower as the regeneration gas. The regeneration gas containing nitrogen desorbed from the adsorption tower is discharged outside the system. After the desorption of nitrogen is completed, the cooling process begins. In this embodiment 1, during the cooling process, the gas phase gas from the gas-liquid separator 15 is introduced into the heater 13 via the regeneration gas introduction line 16, the gas is heated to 65 K by the heater 13, and the gas is introduced from the outlet side of the adsorption tower as the regeneration gas. The regeneration gas was discharged outside the system. The regeneration process was completed when the adsorption tower was cooled to 68 K. The regeneration gas flow rate was 1.7 Nm3 in both processes. 3 / h.

[0057] The outlet purified gas of the low-temperature adsorber 12 was introduced into the heat exchanger 14, where the gas consisting of neon and helium was cooled to 31K and introduced into the gas-liquid separator 15. The gas phase gas of the gas-liquid separator 15 consisted of neon and helium, and contained more than 85% helium. As mentioned above, it was used as the regeneration gas for the low-temperature adsorber 12. The liquefied gas on the liquid phase side of the gas-liquid separator 15 was reduced in pressure to 3 bar via the expansion valve 17, and then introduced into the top side of the distillation column 18, where neon and helium were distilled and separated by gas-liquid contact. The distillation column 18 was a packed column filled with random packing. The distillation column 18 was equipped with a reboiler 19, which was an electric heater type. The top gas of the distillation column 18 contained neon, so it was refluxed to the buffer container 2. Neon was concentrated at the bottom of the distillation column 18 and was extracted as a high-purity neon gas product via a compressor 20. The high-purity neon had a neon concentration of 99.99% or more and its flow rate was 4.6 Nm 3 / h.

[0058] The neon refining apparatus 100 was equipped with a cryogenic refrigerator 21 as a cold source, which supplied a refrigerant to the heat exchangers 8 and 14. The cryogenic refrigerator 21 was of the Brayton cycle type, and a turbo compressor was used as the circulation compressor for the refrigerant. Helium gas was used as the refrigerant. In this embodiment 1, the cryogenic refrigerator 21 required 28 kW of power to operate.

[0059] For comparison, when the outlet gas of the low-temperature adsorber 12 is used as the regeneration gas instead of the gas phase gas of the gas-liquid separator 15, the regeneration gas pressure is 1.7 Nm 3 / h of gas must be used as regeneration gas. In that case, the outlet gas of the low-temperature adsorber 12 used as regeneration gas must be returned to the buffer vessel 2 in order to reduce neon loss. As a result, the amount of gas circulating in the neon purification apparatus 100 increases, and the amount of refrigeration required increases. In the above operating method, the operating power of the cryogenic refrigerator 21 was 32 kW.

[0060] In other words, by utilizing the technology of the present invention, it was possible to reduce the power required for high-purity neon production (neon purification) by 15%.

[0061] Example 2 In Example 2, high-purity neon was produced (neon was purified) using the neon purification apparatus 200 shown in FIG.

[0062] First, crude neon gas was supplied to the buffer container 32 through the crude neon gas supply line 31. The specifications of the crude neon gas were as shown in Table 1, similar to Example 1.

[0063] Next, the raw gas in the buffer container 32 was introduced into the compressor 33. In the compressor 33, the raw gas was compressed to 30 bar. 3 Oxygen gas was added at a flow rate of 10000 kcal / h, and the mixture of the raw gas and oxygen was sent to the hydrogen oxidation tower 34. The hydrogen oxidation tower 34 was heated by an external heater, and the hydrogen and oxygen in the raw gas were reacted with each other through a catalytic reaction, converting them into water. The outlet gas of the hydrogen oxidation tower 34 passed through a cooler 35 and was introduced into a gas-liquid separator 36, where most of the moisture was removed. The gas on the gas phase side of the gas-liquid separator 36 was introduced into a moisture removal tower 37, where the moisture and CO2 in the gas were removed, and the respective concentrations became less than 10 ppb. The moisture removal tower 37 was a two-tower type, with one tower for the adsorption process and the other for the regeneration process. Each tower was filled with molecular sieves.

[0064] The neon-containing gas from the outlet of the moisture removal tower 37 was introduced into the nitrogen adsorption tower 38. The nitrogen concentration in the neon-containing gas was 10 ppm. The nitrogen adsorption tower 38 was a four-tower type, with one tower in the adsorption process, another in the regeneration process, and the remaining two towers in the pressure equalization process performed when switching between towers (FIG. 2 shows a two-tower type, but in Example 2 it is a four-tower type). Each adsorption tower was filled with zeolite as an adsorbent. The regeneration process of the nitrogen adsorption tower 38 consists of a depressurization process, a vacuum exhaust process, and an exhaust regeneration process. The depressurization process is a process of distributing the pressure during adsorption to the towers in the pressure equalization process. In this Example 2, the pressure was depressurized to 7.5 bar by two pressure equalization processes. The exhaust process is a process of desorbing the adsorbed nitrogen by evacuating the adsorption tower using a vacuum pump 39. In this Example 2, the exhaust process was performed by evacuating to 0.05 bar. The exhaust gas at this time was discharged outside the system. The evacuation regeneration step is a step in which desorption of nitrogen is further promoted by flowing a regeneration gas while performing evacuation by a vacuum pump 39. In this Example 2, the gas phase gas of a gas-liquid separator 43 was used as the regeneration gas via a regeneration gas introduction line 44. The regeneration gas containing the adsorbed nitrogen was discharged outside the system via a vacuum pump 39. The flow rate of the regeneration gas was 1.6 Nm 3 At this time, the recovery rate of the neon-containing gas in the nitrogen adsorption tower 38 was 90%.

[0065] The neon-containing gas at the outlet of the nitrogen adsorption tower 38 was introduced into the heat exchanger 40 in the cold box 50. The neon-containing gas was cooled to 68 K in the heat exchanger 40 and introduced into the guard absorber 41. The nitrogen concentration at the outlet of the guard absorber 41 was less than 10 ppb.

[0066] The outlet refined gas of the guard absorber 41 was introduced into the heat exchanger 42, where the gas consisting of neon and helium was cooled to 31K and introduced into the gas-liquid separator 43. The gas phase gas of the gas-liquid separator 43 consisted of neon and helium, and contained 85% or more of helium. As mentioned above, the gas was used as the regeneration gas for the nitrogen adsorption tower 38 through the regeneration gas introduction line 44. The liquefied gas on the liquid phase side of the gas-liquid separator 43 was reduced in pressure to 3 bar through the expansion valve 45, and then introduced into the top side of the distillation tower 46, where the neon and helium were distilled and separated by gas-liquid contact. The distillation tower 46 was a packed tower filled with random packing. The distillation tower 46 was equipped with a reboiler 47, which was an electric heater type. The top gas of the distillation tower 46 contained neon, so it was refluxed to the buffer container 32. Neon was concentrated at the bottom of the distillation column 46 and was extracted as a high-purity neon gas product via a compressor 48. The high-purity neon had a neon concentration of 99.99% or more and a flow rate of 4.0 Nm 3 / h.

[0067] The neon refining apparatus 200 was equipped with a cryogenic refrigerator 49 as a cold source, which supplied a refrigerant to the heat exchangers 40 and 42. The cryogenic refrigerator 49 was of the Brayton cycle type, and a turbo compressor was used as the circulation compressor for the refrigerant. Helium gas was used as the refrigerant. In this embodiment 2, the cryogenic refrigerator 49 required 23 kW of power to operate.

[0068] For comparison, if regeneration gas is not used in the regeneration process of the nitrogen adsorption tower 38 and regeneration is carried out only in the exhaust process, the adsorbent performance cannot be utilized to its full extent, so the amount of adsorbent must be increased, which increases the loss of neon-containing gas. In the above case, the recovery rate of neon-containing gas in the nitrogen adsorption tower 38 is 85%. Therefore, the flow rate of the product high-purity neon gas is 3.7 Nm 3 / h. The operating power of the cryogenic refrigerator 49 at this time was 23 kW, which was the same.

[0069] In other words, by utilizing the technology of this invention, it was possible to increase the production volume of high-purity neon (amount of neon refined) by 8%. [Industrial Applicability]

[0070] The present invention relates to a neon purification apparatus and method. [Explanation of symbols]

[0071] 1, 31: Crude neon gas supply line 2, 32: Buffer container 3, 33, 20, 48: Compressor 4, 34: Hydrogen oxidation tower 5, 35: Cooler 7, 37: Moisture removal tower 8, 14, 40, 42: Heat exchanger 6,9,11,15,36,43: Gas-liquid separator 10, 17, 45: Expansion valve 12: Low temperature adsorption device 13: Heater 16, 44: Regenerated gas introduction line 18, 46: Distillation tower 19, 47: Reboiler 21, 49: Cryogenic refrigerator 22, 50: Cold box 38: Nitrogen removal tower 41: Guard absorber 100, 200: Neon Refining Device 102, 232: mixed gas introduction line 109: Spare separation unit 112, 138: Adsorption part 115, 143: Separation part 312, 438: Discharge line 313, 439: Used gas return line 315, 443: Nitrogen removal gas introduction line 318, 246: Distillation column gas reflux line

Claims

1. an adsorption section that adsorbs and removes nitrogen from a mixed gas containing neon, helium, and nitrogen; a separation section that separates and removes helium from the nitrogen-removed gas from which nitrogen has been adsorbed and removed in the adsorption section; a regeneration gas introduction line capable of introducing a separated gas containing helium separated and removed in the separation section into the adsorption section as a regeneration gas for regenerating the adsorption capacity of the adsorption section.

2. a buffer container in which a source gas serving as a source of the mixed gas is stored; 2. The neon purification apparatus according to claim 1, further comprising: a used gas reflux line capable of introducing into the buffer container a mixed used gas of the regeneration gas and a desorbed gas containing nitrogen desorbed from the adsorption section as a result of the regeneration gas being introduced into the adsorption section.

3. a distillation column for further separating and removing helium from the helium-removed gas from which helium has been separated and removed in the separation section; 3. The neon purification apparatus according to claim 2, further comprising: a distillation column gas reflux line capable of introducing distillation column gas containing helium separated and removed in the distillation column into the buffer vessel.

4. 4. The neon purification apparatus of claim 2, further comprising a heat exchanger capable of cooling the mixed gas before it is introduced into the adsorption section.

5. a preliminary separation section for separating and removing nitrogen from the mixed gas before the mixed gas is introduced into the adsorption section; The neon purification apparatus according to claim 4 , further comprising: a pre-separation gas return line capable of introducing a pre-separation gas containing nitrogen separated and removed in the pre-separation section into the buffer container.

6. 4. The neon purification apparatus according to claim 1, further comprising a guard absorber for further removing nitrogen from the nitrogen-removing gas before the nitrogen-removing gas is introduced into the separation section.

7. A method for refining neon using the neon refining apparatus according to any one of claims 1 to 3.

Images