Neon purification device and neon purification method

Abstract

A neon purification device according to the present invention comprises: an adsorption unit that adsorbs and removes nitrogen from a mixed gas containing neon, helium, and nitrogen; a separation unit that separates and removes helium from the nitrogen-removed gas from which nitrogen has been adsorbed and removed by the adsorption unit; and a regeneration gas introduction line that can introduce a separation gas containing helium separated and removed by the separation unit into the adsorption unit as a regeneration gas for regenerating the adsorption capacity of the adsorption unit.

Description

Neon refining device and neon refining method

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

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

[0003] Patent Document 1 describes a process in which neon is purified as liquefied neon using a hydrogen oxidation section, a moisture removal section, a nitrogen liquefaction removal section at low temperatures, a residual nitrogen removal section at low temperatures by adsorption, and a fractionation column.

[0004] US Pat. No. 5,629,999 describes a nitrogen removal section, a process for separating helium, neon and hydrogen by cryogenic adsorption.

[0005] U.S. Patent No. 10,767,923, Japanese Patent No. 3,268,177

[0006] In the process of Patent Document 1, neon is purified from a mixed gas containing at least neon, nitrogen, and helium by removing nitrogen and other elements through low-temperature adsorption. Therefore, the adsorbent must be regenerated using a temperature swing method, in which the adsorption tower is heated to desorb the adsorbed components from the adsorbent. In this case, the gas purified by low-temperature adsorption must be used as the regeneration gas to promote desorption of the adsorbed components from the adsorbent. However, when the regeneration gas flow rate is low, the time required to heat the adsorption tower and desorb the adsorbed components increases, resulting in an increased device size. Meanwhile, when the regeneration gas flow rate is high, a large amount of the gas purified by low-temperature adsorption is consumed, resulting in a reduced product discharge flow rate.

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

[0008] An object of the present invention is to provide a neon purification apparatus and a neon purification method that can efficiently purify neon from a gas containing neon, nitrogen, and helium.

[0009] A neon purification apparatus according to a first aspect of the present invention is (1) a neon purification apparatus comprising: 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 obtained by adsorption and removal in the adsorption section; and a regeneration gas introduction line that can introduce the 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.

[0010] One embodiment of the neon purification apparatus of the present invention is the neon purification apparatus described in (1) above, including: (2) a buffer container in which a raw material gas serving as a raw material for the mixed gas is stored; and a used gas reflux line capable of introducing into the buffer container a used gas that is a mixture 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] A neon purification apparatus according to one embodiment of the present invention is the neon purification apparatus described in (2) above, further comprising: a distillation column that further separates and removes 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 that can introduce the distillation column gas containing the helium separated and removed in the distillation column into the buffer container.

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

[0013] A neon purification apparatus according to one embodiment of the present invention is (5) the neon purification apparatus described in (4) above, further comprising: a preliminary separation section that separates and removes nitrogen from the mixed gas before the mixed gas is introduced into the adsorption section; and a preliminary separation gas reflux line that can introduce the preliminary separation gas containing the nitrogen separated and removed in the preliminary separation section into the buffer container.

[0014] A neon purification apparatus according to one embodiment of the present invention is (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-removed gas before the nitrogen-removed gas is introduced into the separation section.

[0015] A neon purification method according to a second aspect of the present invention is (7) a neon purification method using the neon purification apparatus according to any one of (1) to (6) above.

[0016] According to the present invention, it is possible to provide a neon purification apparatus and a neon purification method that can efficiently purify neon from a gas containing neon, nitrogen, and helium.

[0017] 1A and 1B are diagrams showing a neon purification apparatus according to a first embodiment of the present invention, and a neon purification apparatus according to a second embodiment of the present invention.

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

[0019] 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 the neon refiner 100 and a neon refinement method using the 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 refers to the gas stored in the buffer container 2, specifically, the crude neon gas or a mixture of the crude neon gas and the reflux gas from the neon purification apparatus 100. Examples of reflux gas include, but are not limited to, the reflux gas from the pre-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 buffer container 2 may be made of either metal or resin.

[0022] The neon purification apparatus 100 of this embodiment includes a mixed gas inlet line 102 that connects the buffer container 2 with an adsorption unit 112 (described later). The mixed gas inlet 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 inlet line 102 is not limited thereto. Hereinafter, for ease of explanation, the gas introduced into the adsorption unit 112 via the mixed gas inlet 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 container 2 is a gas that serves as a raw material for the mixed gas.

[0023] The compressor 3 is capable of pressurizing the feed gas to a pressure required for the process. The feed 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 feed gas introduced into the hydrogen oxidation tower 4 may be heated, for example, by externally heating the hydrogen oxidation tower 4. Alternatively, the feed gas introduced into the hydrogen oxidation tower 4 may be heated, for example, by a heating unit provided in the hydrogen oxidation tower 4. By adding oxygen gas to the feed gas before it is introduced into the hydrogen oxidation tower 4, the hydrogen and oxygen in the feed gas are thermally reacted in the hydrogen oxidation tower 4 and converted into water. Examples of catalysts include, but are not limited to, platinum, palladium, copper, and the like. The feed gas discharged from the hydrogen oxidation tower 4 passes through a cooler 5, and the heated feed gas in the hydrogen oxidation tower 4 is cooled to below room temperature. The cooled feed gas is introduced into a gas-liquid separator 6. The gas introduced into the gas-liquid separator 6 is separated into a liquid phase, with condensed water being cooled, and the remaining gas being separated into a gas phase.

[0024] The neon-containing gas on the gas-phase side of the gas-liquid separator 6 is introduced into the moisture removal tower 7. The moisture removal tower 7 uses a method of repeating adsorption and desorption by temperature swing. The moisture removal tower 7 is filled with a desiccant. This desiccant adsorbs moisture and CO ２ The desiccant may be, but is not limited to, molecular sieves, silica gel, activated alumina, etc. The moisture removal tower 7 is mainly composed of at least two towers, and during operation of the apparatus, an adsorption step is carried out in one tower, and a regeneration step is carried out in another tower. During regeneration, the tower is heated by an external heater or heated nitrogen gas, etc., to remove the adsorbed moisture and CO ２ The blowdown gas generated when switching between the adsorption step and the regeneration step may be recovered as reflux gas in the buffer vessel 2. By recovering the blowdown gas as reflux gas, the yield of the product neon relative to the total amount of the raw gas can be improved.

[0025] The moisture removal tower 7 removes moisture and CO ２The mixed gas containing neon, helium, and nitrogen from which the oxidants have been removed is introduced into heat exchanger 8 in cold box 22. In heat exchanger 8, the mixed gas is introduced as a warm fluid and cooled to a temperature between 65 K and 100 K, for example. A liquefied gas containing nitrogen as a main component, separated in a process in gas-liquid separator 11 (described later), is also introduced into heat exchanger 8 as a cold fluid. Furthermore, neon purification apparatus 100 of this embodiment is equipped with cryogenic refrigerator 21, and a circulating refrigerant from cryogenic refrigerator 21 is supplied to heat exchanger 8. The cryogenic refrigerator 21 may be, but is not limited to, a Brayton cycle. The circulating refrigerant may be helium, neon, hydrogen, or a mixture thereof.

[0026] The mixed gas containing neon, helium, and nitrogen cooled in 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, which will be described later. More specifically, the preliminary separation section 109 of this embodiment is a gas-liquid separator 9 that can separate a liquefied gas containing nitrogen as a main component into a liquid phase and a gas containing neon as a main component into a gas phase. The neon purification apparatus 100 of this embodiment also includes a preliminary separation gas reflux line 309 that can introduce 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 that connects 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, primarily composed of nitrogen, separated and removed in gas-liquid separator 9 is sent to expansion valve 10, where it is decompressed by Joule-Thomson expansion and introduced into gas-liquid separator 11. In gas-liquid separator 11, a liquefied gas containing 95% or more nitrogen is separated into the liquid phase and a gas enriched with neon and helium is separated into the gas phase. As described above, the liquefied gas containing 95% or more nitrogen is introduced as a cold fluid into heat exchanger 8, where it is vaporized and released into the atmosphere. The gas on the gas phase side of gas-liquid separator 11 is returned to buffer vessel 2 via pre-separated gas return line 309. This improves the yield of product neon relative to the total amount of feed gas.

[0027] The mixed gas containing neon, helium, and nitrogen from 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 in this embodiment is a low-temperature adsorber 12 employing a temperature swing adsorption (TSA) system, which repeatedly performs adsorption and desorption by temperature swing. However, the low-temperature adsorber 12 may also be a pressure swing adsorption (PSA) system or a pressure swing adsorption (VPSA) system using a vacuum pump. The low-temperature adsorber 12 is filled with an adsorbent and is capable of removing nitrogen from a mixed gas containing neon as a main component at temperatures between 65 K and 100 K. Examples of adsorbents include, but are not limited to, molecular sieves and activated carbon. The low-temperature adsorber 12 is primarily composed of at least two or more towers. During operation, one tower performs an adsorption process, while another tower performs a regeneration process.

[0028] The neon purification apparatus 100 of this embodiment includes a regeneration gas inlet line 16 that can introduce the separated gas containing helium separated and removed in the separation unit 115 (described below) into the adsorption unit 112 as a regeneration gas for regenerating the adsorption capacity of the adsorption unit 112. More specifically, the regeneration gas inlet line 16 of this embodiment connects the gas-liquid separator 15 (described below) serving as the separation unit 115 to the low-temperature adsorber 12 (described below). By providing this regeneration gas inlet line 16, the gas phase gas from the gas-liquid separator 15 can be used as the regeneration gas for the low-temperature adsorber 12. Normally, the purified gas at the outlet of the low-temperature adsorber 12 is used as the regeneration gas. However, this regeneration gas must be returned to the buffer vessel 2 to reduce neon loss. In this case, the amount of process gas circulated increases. This increases the load on the cryogenic refrigerator 21, which generates refrigeration, and increases the power required for producing high-purity neon. On the other hand, in this embodiment, the gas phase gas from the gas-liquid separator 15 is used as the regeneration gas via the regeneration gas inlet line 16. Due to the mass balance of the process, this vapor phase gas must be vented, and its use as regeneration gas does not increase neon loss. Therefore, the neon yield can be maintained and the power required for producing high-purity neon can be reduced without increasing the process gas flow rate. In other words, neon can be efficiently purified from a gas containing neon, nitrogen, and helium. A heater 13 is provided in the regeneration gas inlet line 16, which introduces the regeneration gas into the low-temperature adsorber 12, to heat the regeneration gas during thermal regeneration. An external heater may also be provided in the adsorption section 112.

[0029] In this embodiment, the adsorption section 112 is connected to a discharge line 312 that can discharge, to the outside of the neon purification apparatus 100, the blowdown gas from the adsorption section 112 and the spent gas, which is a mixture of the regeneration gas and the desorbed gas containing nitrogen desorbed from the adsorption section 112 as a result of the regeneration gas being introduced into the adsorption section 112. A spent gas reflux line 313 may be connected to the discharge line 312 as a branch line. The spent gas reflux line 313 connects the adsorption section 112 and the buffer container 2. The provision of such a spent gas reflux line 313 makes it possible to introduce the blowdown gas or the spent gas into the buffer container 2 as reflux gas. In other words, the provision of such a spent gas reflux line 313 can improve the yield of the neon product relative to the total amount of feed gas.

[0030] The neon purification apparatus 100 of this embodiment includes a nitrogen removal gas introduction line 315 that connects the adsorption section 112 and the separation section 115, which will be described later. The nitrogen removal gas introduction line 315 of this embodiment is provided with a heat exchanger 14. However, the configuration of the nitrogen removal gas introduction line 315 is not limited to this. Hereinafter, for convenience of explanation, the gas introduced into the separation section 115 via the nitrogen removal gas introduction line 315 may be collectively referred to as the "nitrogen removal gas from which nitrogen has been adsorbed and removed in the adsorption section 112" or simply as the "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. While FIG. 1 illustrates a configuration in which the circulating refrigerant of the cryogenic refrigerator 21 circulates through the heat exchangers 14 and 8 connected in series to the cryogenic refrigerator 21, the circulating refrigerant of the cryogenic refrigerator 21 may also be circulated through the heat exchangers 14 and 8 connected in parallel to the cryogenic refrigerator 21. Alternatively, separate refrigerators may be provided for 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 that can separate from the nitrogen-removed gas a liquefied gas containing neon as a main component into a liquid phase and a gas containing helium as a main component into a gas phase. 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 in the liquid phase of the gas-liquid separator 15 is primarily composed of neon and is introduced into the expansion valve 17. The liquefied gas is reduced in pressure by Joule-Thomson expansion in the expansion valve 17 and introduced into the top 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 at the top, and high-purity neon of 99% or more is concentrated at the bottom. The neon extracted from the bottom of the distillation column 18 is compressed by a compressor 20 and extracted as product neon. When the product neon is extracted in liquid form, a liquid pump may be used instead of the compressor 20. Furthermore, if compression of the product is not necessary, the product neon may be extracted without using the compressor 20. The distillation column 18 is equipped with a reboiler 19 that vaporizes the descending liquid to produce an ascending gas. The distillation column 18 may be a structured packed column, a random packed column, or a plate column. The reboiler 19 may be heated by, but is not limited to, an electric heater or a separate warm fluid via a heat exchanger. Although not shown in FIG. 1 , the distillation column 18 may be equipped with a condenser that cools the ascending gas to produce a descending liquid. The neon purification system 100 of this embodiment also includes a distillation column gas reflux line 318 that can introduce the helium-containing distillation column gas separated and removed in the distillation column 18 into the buffer container 2. More specifically, the distillation column gas reflux line 318 connects the top of the distillation column 18 to the buffer container 2. By providing such a distillation column gas reflux line 318, the distillation column gas containing helium concentrated at the top of the distillation column 18 can be introduced into the buffer container 2 via the distillation column gas reflux line 318 as reflux gas. As a result, the yield of the neon product relative to the total amount of the raw material gas can be improved.

[0034] 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 the neon refiner 200 and a neon refinement method using the neon refiner 200 will be described below.

[0035] Crude neon gas supply line 31 is a line that supplies crude neon gas to 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] The buffer container 32 receives the crude neon gas from the crude neon gas supply line 31 and the reflux gas that is refluxed as part of the process of the neon purification apparatus 200, and can store and hold them as raw material gas. Here, the raw material gas refers to the gas stored in the buffer container 32, specifically the crude neon gas or a mixture of the crude neon gas and the reflux gas from the neon purification apparatus 200. Examples of reflux gas include, but are not limited to, the reflux gas from the adsorption section 138 (described below) and the reflux gas from the distillation column 46 (described below). The buffer container 32 may be made of either metal or resin.

[0037] The neon purification apparatus 200 of this embodiment includes a mixed gas inlet line 232 that connects the buffer container 32 with the adsorption unit 138, which will be described later. The mixed gas inlet 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 inlet line 232 is not limited to this. Hereinafter, for ease of explanation, the gas introduced into the adsorption unit 138 via the mixed gas inlet 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 container 32 is a gas that serves as a raw material for the mixed gas.

[0038] The compressor 33 can pressurize the feed gas to a pressure required for the process. The feed gas pressurized by the compressor 33 is supplied to the hydrogen oxidation tower 34. The hydrogen oxidation tower 34 is filled with a catalyst. The feed gas introduced into the hydrogen oxidation tower 34 may be heated, for example, by externally heating the hydrogen oxidation tower 34. Alternatively, the feed gas introduced into the hydrogen oxidation tower 34 may be heated, for example, by a heating unit provided in the hydrogen oxidation tower 34. By adding oxygen gas to the feed gas before it is introduced into the hydrogen oxidation tower 34, the hydrogen and oxygen in the feed gas are thermally reacted in the hydrogen oxidation tower 34 and converted into water. Examples of catalysts include, but are not limited to, platinum, palladium, copper, and the like. The feed 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 below room temperature. The cooled feed 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 into a liquid phase in which condensed water is cooled, and a gas other than the condensed water is separated into a gas phase.

[0039] The neon-containing gas on the gas-liquid separator 36 is introduced into the moisture removal tower 37. The moisture removal tower 37 uses a temperature swing to repeatedly adsorb and desorb. The moisture removal tower 37 is filled with a desiccant. This desiccant adsorbs moisture and CO ２ The desiccant may be, but is not limited to, molecular sieves, silica gel, activated alumina, etc. The moisture removal tower 37 is composed of at least two towers, and during operation of the apparatus, an adsorption step is carried out in one tower, and a regeneration step is carried out in another tower. During regeneration, the tower is heated by an external heater or heated nitrogen gas, etc., to remove the adsorbed moisture and CO ２ The blowdown gas generated when switching between the adsorption step and the regeneration step may be recovered as reflux gas in the buffer vessel 32. By recovering the blowdown gas as reflux gas, the yield of the product neon relative to the total amount of the feed gas can be improved.

[0040] The moisture removal tower 37 removes moisture and CO ２The mixed gas containing neon, helium, and nitrogen from which the neon has been removed is introduced into the adsorption section 138. The adsorption section 138 adsorbs and removes nitrogen from the mixed gas. In this embodiment, the adsorption section 138 is a nitrogen adsorption tower 38 of a pressure swing type (VPSA) that repeatedly performs 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 that removes mainly nitrogen from the neon-containing gas by adsorption. Examples of adsorbents include, but are not limited to, zeolite and activated carbon. The nitrogen adsorption tower 38 is composed of at least two towers, and preferably three or more towers to reduce neon loss in the nitrogen adsorption tower 38. Each tower constituting the nitrogen adsorption tower 38 is connected to a vacuum pump 39. The vacuum pump 39 is used in the regeneration process of the nitrogen adsorption tower 38 to desorb the adsorbed nitrogen by pressure difference.

[0041] In this embodiment, the adsorption section 138 is connected to an exhaust line 438 that can exhaust, to the outside of the neon purification apparatus 200, the blowdown gas from the adsorption section 138 and the spent gas, which is a mixture of the regeneration gas and the desorbed gas containing nitrogen desorbed from the adsorption section 138 due to the introduction of the regeneration gas into the adsorption section 138. In this embodiment, the vacuum pump 39 is provided on this exhaust line 438. A spent gas reflux line 439 may be connected to this exhaust line 438 as a branch line. The spent gas reflux line 439 connects the adsorption section 138 and the buffer container 32. The provision of this spent gas reflux line 439 makes it possible to introduce the blowdown gas or the spent gas into the buffer container 32 as reflux gas. In other words, the provision of this spent gas reflux line 439 can improve the yield of the neon product relative to the total amount of the feed gas.

[0042] The neon purification apparatus 200 of this embodiment includes a regeneration gas introduction line 44 that can introduce a separated gas containing helium separated and removed in a separation unit 143 (described below) into the adsorption unit 138 as a regeneration gas for regenerating the adsorption capacity of the adsorption unit 138. More specifically, the regeneration gas introduction line 44 of this embodiment connects a gas-liquid separator 43 (as the separation unit 143) (described below) to a nitrogen adsorption tower 38 (as the adsorption unit 138). By providing this regeneration gas introduction line 44, the gas phase gas from 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 promotes desorption of nitrogen adsorbed in the adsorption unit 138, allowing the nitrogen adsorption tower 38 (as the adsorption unit 138) to be designed to be smaller. As a result, neon loss can be reduced, enabling manufacturing costs to be reduced. That is, neon can be efficiently purified from a gas containing neon, nitrogen, and helium. Without the use of a regeneration gas, desorption efficiency decreases, resulting in a decrease in the performance of the adsorption tower, and therefore, an increase in the amount of adsorbent is required. Increasing the size of the adsorption column to increase the amount of adsorbent results in a large loss of neon-containing gas. Furthermore, it is preferable that the gas usable as regeneration gas does not contain nitrogen and does not contain any gas other than crude neon gas components. Gases that meet these conditions are helium gas or product neon gas. However, using the former, helium gas, increases the cost of producing high-purity neon (i.e., the cost of purifying neon) by the amount of helium gas used. Using the latter, product neon gas, also increases the cost of producing high-purity neon due to a decrease in neon yield.

[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, which will be described later. 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 convenience of explanation, the gas introduced into the separation section 143 via 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 apparatus of this embodiment is equipped with a cryogenic refrigerator 49, and a circulating refrigerant from the cryogenic refrigerator 49 is supplied to the heat exchanger 40. The cryogenic refrigerator 49 may be a Brayton cycle refrigerator, but is not limited to this. 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 is capable of removing 10 to 100 ppm of nitrogen from the nitrogen-removed gas that is not completely removed by the adsorption section 138. The guard absorber 41 is filled with an adsorbent, and is capable of removing 10 to 100 ppm of nitrogen from the nitrogen-removed gas that is not completely removed by the adsorption section 138 at temperatures between 44 K and 100 K. Examples of adsorbents include, but are not limited to, molecular sieves and activated carbon. The guard absorber 41 may be designed to maintain its performance by regenerating it when the entire apparatus is returned to room temperature, such as during periodic inspection. Multiple 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 this heat exchanger 42, the nitrogen-removed gas containing neon and helium is introduced as a warm fluid and cooled to a temperature between 25 K and 44 K, for example. A circulating refrigerant from a cryogenic refrigerator 49 is supplied to the heat exchanger 42 via a heat exchanger 40. While FIG. 2 illustrates a configuration in which the circulating refrigerant of the cryogenic refrigerator 49 circulates through the heat exchangers 42 and 40 connected in series to the cryogenic refrigerator 49, the circulating refrigerant of the cryogenic refrigerator 49 may also be circulated through the heat exchangers 42 and 40 connected in parallel to the cryogenic refrigerator 49. Furthermore, separate refrigerators may be provided for the heat exchangers 42 and 40, respectively.

[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 containing neon as a main component into a liquid phase and a gas containing helium as a main component into a gas phase. 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 in the liquid phase of the gas-liquid separator 43, which is primarily composed of neon, is introduced into the expansion valve 45. The liquefied gas is decompressed by Joule-Thomson expansion in the expansion valve 45 and introduced into the top 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 through gas-liquid contact. In the distillation column 46, neon gas containing helium is concentrated at the top, and high-purity neon of 99% or more is concentrated at the bottom. The neon is extracted from the bottom of the distillation column 46, compressed by a compressor 48, and extracted as product neon. When extracting product neon in liquid form, a liquid pump may be used instead of the compressor 48. Furthermore, if compression of the product is not necessary, product neon may be extracted without using the compressor 48. The distillation column 46 is equipped with a reboiler 47 that vaporizes the descending liquid to produce an ascending gas. The distillation column 46 may be a structured packed column, a random packed column, or a plate column. The reboiler 47 may be heated by, but is not limited to, an electric heater or a separate warm fluid via a heat exchanger. Although not shown in FIG. 2 , the distillation column 46 may also be equipped with a condenser that cools the ascending gas to produce a descending liquid. The neon purification system 200 of this embodiment also includes a distillation column gas reflux line 246 that can introduce the distillation column gas containing helium separated and removed in the distillation column 46 into the buffer container 32. More specifically, the distillation column gas reflux line 246 connects the top of the distillation column 46 to the buffer container 32. This allows the distillation column gas concentrated at the top of the distillation column 46 to be introduced into the buffer container 32 via the distillation column gas reflux line 246 as reflux gas. As a result, the yield of the neon product relative to the total amount of the raw material gas can be improved.

[0049] The neon refining apparatus and neon refining 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.

[0050] An example using the neon purification device 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 buffer container 2 through crude neon gas supply line 1. The specifications of the crude neon gas were as shown in Table 1.

[0053]

[0054] Next, the raw material gas in the buffer vessel 2 was introduced into the compressor 3. In the compressor 3, the raw material gas was compressed to 30 bar. ３ Oxygen gas was added at a flow rate of 1000 kJ / h, and the mixture of the raw material 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 material 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 CO in the gas were removed. ２ The moisture removal tower 7 is a two-tower type, with one tower for the adsorption process and the other for the regeneration process. Each tower is packed with molecular sieves.

[0055] The neon-containing gas from 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 68 K in the heat exchanger 8 and introduced into the gas-liquid separator 9. The nitrogen concentration in the gas phase gas from 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 from the gas-liquid separator 11 contained 80% or more neon and was therefore refluxed to the buffer container 2.

[0056] The gas phase gas from the gas-liquid separator 9 was introduced into the low-temperature adsorber 12, where the nitrogen concentration in the neon-containing gas was reduced to less than 10 ppb. The low-temperature adsorber 12 was a two-column system, with one column performing the adsorption process and the other performing the regeneration process. Each adsorption column was filled with activated carbon as an adsorbent. The regeneration process of the low-temperature adsorber 12 mainly consisted of a heating process and a cooling process. In Example 1, during the heating process, the gas phase gas from the gas-liquid separator 15 was introduced into the heater 13 via the regeneration gas inlet line 16. The heater 13 heated the gas to 200 K and introduced it from the outlet side of the adsorption column as regeneration gas. The regeneration gas containing nitrogen desorbed from the adsorption column was released outside the system. After nitrogen desorption was complete, the cooling process began. In Example 1, during the cooling process, the gas phase gas from the gas-liquid separator 15 was introduced into the heater 13 via the regeneration gas inlet line 16. The heater 13 heated the gas to 65 K and introduced it from the outlet side of the adsorption column as 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 purified gas from the outlet of the low-temperature adsorber 12 was introduced into a heat exchanger 14, where the gas composed of neon and helium was cooled to 31 K and introduced into a gas-liquid separator 15. The gas phase gas from the gas-liquid separator 15 consisted of neon and helium, with a helium content of 85% or more. As mentioned above, this gas 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 an expansion valve 17 and then introduced into the top side of a 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 electrically heated. The overhead gas from the distillation column 18 contained neon and was therefore 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 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 refrigerant circulation compressor. Helium gas was used as the refrigerant. In this Example 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 as in Example 1. ３ / h of gas must be used as regeneration gas. In this case, the outlet gas of the low-temperature adsorber 12 used as regeneration gas must be returned to the buffer vessel 2 to reduce neon loss. As a result, the amount of gas circulated in the neon purification system 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 producing high-purity neon (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, the same as in Example 1.

[0063] Next, the raw material gas in the buffer container 32 was introduced into the compressor 33. In the compressor 33, the raw material gas was compressed to 30 bar. ３ Oxygen gas was added at a flow rate of 1000 kJ / h, and the mixture of the raw material 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 material gas were reacted with each other by a catalytic reaction to convert 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 The moisture removal tower 37 is a two-tower type, with one tower for the adsorption process and the other for the regeneration process. Each tower is packed 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 this neon-containing gas was 10 ppm. The nitrogen adsorption tower 38 was a four-tower system, 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 towers (although Figure 2 shows a two-tower system, Example 2 uses a four-tower system). Each adsorption tower was filled with zeolite as an adsorbent. The regeneration process for the nitrogen adsorption tower 38 consisted of a depressurization process, a vacuum pumping process, and an exhaust regeneration process. The depressurization process was a process of distributing the pressure during adsorption to the towers in the pressure equalization process. In Example 2, the pressure was reduced to 7.5 bar through two equalization processes. The exhaust process was a process of desorbing the adsorbed nitrogen by evacuating the adsorption tower using a vacuum pump 39. In Example 2, the exhaust process was performed by evacuating to 0.05 bar. The exhaust gas was then released outside the system. The evacuation regeneration step is a step in which nitrogen desorption is further promoted by flowing a regeneration gas while performing vacuum evacuation using a vacuum pump 39. In this Example 2, the gas phase gas from the 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 the 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 purified gas from the guard absorber 41 was introduced into a heat exchanger 42, where it was cooled to 31 K and introduced into a gas-liquid separator 43. The gas phase gas from the gas-liquid separator 43 consisted of neon and helium, with a helium content of 85% or more. As mentioned above, this gas was used as the regeneration gas for the nitrogen adsorption column 38 via a 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 via an expansion valve 45 and then introduced into the top side of a distillation column 46, where neon and helium were distilled and separated by gas-liquid contact. The distillation column 46 was packed with random packing. The distillation column 46 was equipped with a reboiler 47, which was electrically heated. The overhead gas from the distillation column 46 contained neon and was therefore 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 its flow rate was 4.0 Nm ３ / h.

[0067] The neon refining apparatus 200 was equipped with a cryogenic refrigerator 49 as a cold source, which supplied 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 refrigerant circulation compressor. Helium gas was used as the refrigerant. In this Example 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 performed only in the exhaust process, the adsorbent performance cannot be fully utilized, 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 was 85%. Therefore, the flow rate of the product high-purity neon gas was 3.7 Nm ３ At this time, the operating power of the cryogenic refrigerator 49 was 23 kW, which was the same as the above.

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

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

[0071] 1, 31: Crude neon gas supply line 2, 32: Buffer vessel 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 adsorber 13: Heater 16, 44: Regeneration 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 purification unit 102, 232: Mixed gas introduction line 109: Preliminary separation section 112, 138: Adsorption section 115, 143: Separation section 312, 438: Discharge lines 313, 439: Spent gas reflux lines 315, 443: Nitrogen removal gas introduction lines 318, 246: Distillation column gas reflux lines

Claims

1. A neon purification apparatus comprising: an adsorption unit that adsorbs and removes nitrogen from a mixed gas containing neon, helium, and nitrogen; a separation unit that separates and removes helium from the nitrogen-removed gas obtained by adsorption and removal in the adsorption unit; and a regeneration gas introduction line that can introduce the separated gas containing helium separated and removed in the separation unit into the adsorption unit as a regeneration gas that regenerates the adsorption capacity of the adsorption unit.

2. The neon purification apparatus according to claim 1, comprising: a buffer container in which a raw material gas serving as a raw material for the mixed gas is stored; and a spent gas reflux line capable of introducing into the buffer container a spent gas mixture comprising 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. The neon purification apparatus according to claim 2, further comprising: 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 the distillation column gas containing the helium separated and removed in the distillation column into the buffer container.

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.

5. The neon purification apparatus according to claim 4, further comprising: 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 preliminary separation gas reflux line capable of introducing the preliminary separation gas containing the nitrogen separated and removed in the preliminary separation section into the buffer container.

6. A neon purification apparatus according to any one of claims 1 to 3, further comprising a guard absorber for further removing nitrogen from the nitrogen-removed gas before the nitrogen-removed gas is introduced into the separation section.

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

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