Neon purification device and neon purification method

Abstract

A neon purification device according to the present invention comprises: a first adsorption unit that adsorbs and removes nitrogen and argon from a raw material gas; a cooling unit that cools the raw material gas from which nitrogen and argon have been adsorbed and removed by the first adsorption unit to obtain a cooling gas; and a second adsorption unit that adsorbs and removes one or both of nitrogen and argon from the cooling gas.

Description

Neon purification apparatus and neon purification method

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

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

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

[0004] U.S. Patent No. 10767923

[0005] However, the neon purification apparatus described in Patent Document 1 still has room for improvement from the perspective of the efficiency of purifying neon.

[0006] An object of the present invention is to provide a neon purification apparatus and a neon purification method capable of improving the efficiency of purifying neon.

[0007] The neon purification apparatus according to the first aspect of the present invention includes: (1) a first adsorption unit that adsorbs and removes nitrogen and argon from a raw material gas; a cooling unit that cools the raw material gas from which nitrogen and argon have been adsorbed and removed by the first adsorption unit to obtain a cooled gas; and a second adsorption unit that adsorbs and removes one or both of nitrogen and argon from the cooled gas.

[0008] The neon purification apparatus according to one embodiment of the present invention is the neon purification apparatus according to (1) above, wherein (2) the amount of argon adsorbed and removed by the first adsorption unit from the raw material gas is larger than the amount of argon adsorbed and removed by the second adsorption unit from the cooled gas.

[0009] The neon purification apparatus according to one embodiment of the present invention is the neon purification apparatus according to (1) or (2) above, wherein (3) the concentration of argon in the raw material gas after nitrogen and argon have been adsorbed and removed by the first adsorption unit is 10 volppm or less.

[0010] One embodiment of the present invention is a neon purification apparatus according to any one of (1) to (3) above, wherein (4) oxygen gas containing argon is added to the raw material gas before it is supplied to the first adsorption unit.

[0011] One embodiment of the present invention is a neon purification apparatus, which is (5) a neon purification method performed using the neon purification apparatus described in any one of (1) to (4) above.

[0012] According to the present invention, it is possible to provide a neon purification apparatus and a neon purification method that can improve the efficiency of neon purification.

[0013] This figure shows a neon refining apparatus according to one embodiment of the present invention.

[0014] Hereinafter, embodiments of the neon purification apparatus and neon purification method according to the present invention will be illustrated and described with reference to the drawings.

[0015] Figure 1 shows a neon purification apparatus 100 as one embodiment of the neon purification apparatus according to the present invention. Crude neon gas containing neon, helium, nitrogen, and hydrogen is supplied to the neon purification apparatus 100. The neon purification apparatus 100 is a device that purifies neon from this crude neon gas. Crude neon gas is produced as a byproduct when producing oxygen, nitrogen, and argon from raw air using an air separation device. The main composition of the crude neon gas supplied to the neon purification apparatus 100 is, for example, 50 vol% neon, 15 vol% helium, 2 vol% hydrogen, and the remainder nitrogen. However, the composition of the crude neon gas is not limited to the above and may vary depending on the configuration of the air separation device that produces the crude neon gas.

[0016] Buffer container 1 receives crude neon gas supplied from crude neon gas supply line 101 and reflux gas refluxed in part of the process of neon purification apparatus 100, and stores and retains the mixed gas as raw material gas. Examples of reflux gas include, but are not limited to, the gas exhausted from the moisture removal unit 6, the gas exhausted from the first adsorption unit 7, and the gas exhausted from the distillation column 13. Buffer container 1 may not accept reflux gas and may only store crude neon gas as raw material gas. Furthermore, the neon purification apparatus 100 does not need to have buffer container 1. In this case, the crude neon gas and reflux gas may be mixed, for example, within the crude neon gas supply line 101 and used as raw material gas.

[0017] The raw material gas discharged from the buffer container 1 is pressurized to the pressure required for the process by the compressor 2. The pressurized raw material gas is supplied to the hydrogen oxidation section 3. The raw material gas supplied to the hydrogen oxidation section 3 may be heated by a heater before being supplied to the hydrogen oxidation section 3, or it may be heated by a heater provided in the hydrogen oxidation section 3 after being supplied to the hydrogen oxidation section 3. In addition, oxygen gas is added to the raw material gas before it is supplied to the hydrogen oxidation section 3. As a result, the hydrogen and oxygen in the raw material gas react in the hydrogen oxidation section 3, and water is produced by the oxidation of hydrogen. As will be described in detail later, the oxygen gas contains argon in addition to oxygen. The hydrogen oxidation section 3 is equipped with a catalyst that promotes the reaction between hydrogen and oxygen. In this embodiment, the hydrogen oxidation section 3 includes a hydrogen oxidation tower, and the catalyst is packed inside the hydrogen oxidation tower. Examples of catalysts include platinum, palladium, and copper, but are not limited to these. The raw material gas whose temperature has risen due to the reaction heat of the catalytic reaction in the hydrogen oxidation section 3 is introduced into a cooler 4 and cooled to below room temperature. The raw material gas cooled by the cooler 4 is introduced into the ambient temperature gas-liquid separator 5. This separates the water that has condensed due to cooling in the cooler 4 into the liquid phase, and the other components into the gas phase.

[0018] The raw material gas separated to the gas phase in the ambient temperature gas-liquid separator 5 is introduced into the moisture removal unit 6. The moisture removal unit 6 is a device that removes moisture and carbon dioxide from the raw material gas using a thermal swing adsorption (TSA) method (hereinafter simply referred to as the "TSA method"), which involves repeated adsorption and regeneration due to temperature differences.

[0019] The moisture removal unit 6 is equipped with an adsorbent. This adsorbent adsorbs and removes moisture and carbon dioxide from the raw material gas. The moisture adsorbed and removed in the moisture removal unit 6 is produced in the hydrogen oxidation unit 3 when hydrogen contained in the raw material gas reacts with oxygen. The carbon dioxide adsorbed and removed in the moisture removal unit 6 is produced in the hydrogen oxidation unit 3 when carbon monoxide contained in the raw material gas reacts with oxygen. Examples of adsorbents used in the moisture removal unit 6 include, but are not limited to, zeolite, silica gel, and activated alumina.

[0020] The moisture removal unit 6 of this embodiment includes at least two adsorption towers. Each of the at least two adsorption towers is filled with the adsorbent described above. During operation of the neon purification apparatus 100, an adsorption process is performed in at least one of the at least two adsorption towers to adsorb and remove moisture and carbon dioxide from the raw gas, and a regeneration process is performed in the other at least one adsorption tower to dehydrate moisture and carbon dioxide from the adsorbent. This adsorption process and regeneration process are performed by switching between the at least two adsorption towers of the moisture removal unit 6. In the regeneration process, a regeneration gas is supplied to the moisture removal unit 6 to promote the dehydration of moisture and carbon dioxide from the adsorbent. This regeneration gas may be supplied to the moisture removal unit 6 in a heated state by an external heater or the like.

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

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

[0023] The raw material gas from which moisture and carbon dioxide have been removed by the moisture removal unit 6 is supplied to the first adsorption unit 7. The first adsorption unit 7 removes most of the nitrogen contained in this raw material gas. The nitrogen adsorbed and removed by the first adsorption unit 7 is contained in the crude neon gas. In addition to nitrogen, the first adsorption unit 7 also adsorbs and removes argon from the raw material gas. This improves the efficiency of neon purification in the neon purification apparatus 100. The details are explained below.

[0024] The raw material gas supplied to the first adsorption unit 7 contains argon. This argon is present in the oxygen gas added to the raw material gas before it is supplied to the first adsorption unit 7 (more specifically, the hydrogen oxidation unit 3). Specifically, the oxygen gas used in typical industrial processes, which is produced by liquefying and distilling air, contains approximately 2,000 to 4,000 vol ppm of argon in addition to its main component, oxygen. This argon is not removed from the raw material gas between the hydrogen oxidation unit 3 and the moisture removal unit 6. Therefore, the raw material gas is supplied to the first adsorption unit 7 containing argon. The concentration of argon in the raw material gas supplied to the first adsorption unit 7 depends on the argon concentration in the oxygen gas and the amount of oxygen gas added to the raw material gas, but is generally about 10 to 500 vol ppm. This argon in the raw material gas can cause problems such as solidification in the cold box 20 and blockage of the line, and can also reduce the purity of the neon product, so it needs to be sufficiently removed from the raw material gas during the process.

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

[0026] In contrast, the first adsorption unit 7 adsorbs and removes argon from the raw material gas in addition to nitrogen. The presence of this first adsorption unit 7 allows for the removal of argon from the raw material gas before the cooling gas is supplied to the second adsorption unit 9. This reduces the amount of argon in the cooling gas supplied to the second adsorption unit 9, suppressing the need to increase the amount of adsorbent in the second adsorption unit 9 and preventing an increase in the operating power of the cryogenic refrigerator 21. As a result, the efficiency of neon purification can be improved.

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

[0028] As described above, if the amount of argon in the cooling gas supplied to the second adsorption unit 9 is large, the operating power of the cryogenic refrigerator 21 will increase, which may reduce the efficiency of neon purification. Similarly, if the amount of nitrogen in the cooling gas supplied to the second adsorption unit 9 is large, the operating power of the cryogenic refrigerator 21 will increase for the same reasons as with argon, which may reduce the efficiency of neon purification. Therefore, from the viewpoint of improving the efficiency of neon purification, the concentrations of nitrogen and argon in the raw material gas after nitrogen and argon have been adsorbed and removed in the first adsorption unit 7 are preferably 10 vol ppm or less, and more preferably 1 vol ppm or less.

[0029] If the raw material gas contains oxygen, the first adsorption unit 7 may remove oxygen from the raw material gas in addition to nitrogen and argon. This oxygen is contained in the oxygen gas added to the raw material gas before it is supplied to the first adsorption unit 7 (more specifically, the hydrogen oxidation unit 3). Specifically, this oxygen is the oxygen contained in the oxygen gas that is not removed from the raw material gas by the hydrogen oxidation unit 3, the cooler 4, and the moisture removal unit 6, and remains in the raw material gas. If the amount of oxygen in the cooling gas supplied to the second adsorption unit 9 is large, the operating power of the cryogenic refrigerator 21 will increase for the same reasons as for argon and nitrogen, and the efficiency of neon purification may decrease. Therefore, from the viewpoint of improving the efficiency of neon purification, the concentration of oxygen in the raw material gas after nitrogen, argon, and oxygen have been adsorbed and removed in the first adsorption unit 7 is preferably 10 vol ppm or less, and more preferably 1 vol ppm or less.

[0030] The first adsorption unit 7 of this embodiment is a device that removes nitrogen from a raw material gas by a pressure swing adsorption (VPSA) method (hereinafter simply referred to as the "VPSA method") which repeats adsorption and regeneration by pressure swing using a vacuum pump. However, the first adsorption unit 7 may also be configured using the TSA method, or it may be configured using a pressure swing adsorption (PSA) method (hereinafter simply referred to as the "PSA method") which does not use a vacuum pump.

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

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

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

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

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

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

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

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

[0039] The raw material gas from which nitrogen and argon, or both, have been removed in the second adsorption unit 9 is introduced into the second heat exchanger 10. The raw material gas is introduced into the second heat exchanger 10 as a warm fluid and is cooled by the second heat exchanger 10 to a temperature, for example, between 25K and 44K. The second heat exchanger 10 is supplied with circulating refrigerant from the cryogenic refrigerator 21 via the first heat exchanger 8. Figure 1 illustrates a configuration in which the circulating refrigerant of the cryogenic refrigerator 21 circulates through the first heat exchanger 8 and the second heat exchanger 10, which are connected in series with the cryogenic refrigerator 21. However, the circulating refrigerant of the cryogenic refrigerator 21 may also circulate through the first heat exchanger 8 and the second heat exchanger 10, which are connected in parallel with the cryogenic refrigerator 21. Alternatively, a separate refrigerator may be provided for each of the first heat exchanger 8 and the second heat exchanger 10.

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

[0041] The separation liquid mainly composed of neon separated by the helium removal unit 11 is introduced into the expansion valve 12. This separation liquid is depressurized by Joule-Thomson expansion by the expansion valve 12 and then introduced into the top side of the distillation column 13. In the distillation column 13, the raw material gas from which the separation gas mainly composed of helium has been separated and removed in the helium removal unit 11, that is, further helium is removed from the above-mentioned separation liquid. Specifically, when the raw material gas is supplied to the distillation column 13, neon gas containing helium is concentrated on the top side, and high-purity neon of 99 vol% or more is concentrated on the bottom side. This high-purity neon is withdrawn from the bottom side of the distillation column 13, compressed by the compressor 15, and taken out as product neon. When the product neon is taken out in liquid form from the distillation column 13, a liquid transfer pump may be used instead of the compressor 15. Also, the product neon may be taken out without using the compressor 15. The distillation column 13 is equipped with a reboiler 14 that vaporizes the descending liquid into rising gas. The distillation column 13 may be any of a regular packed column, an irregular packed column, and a tray column. Examples of the heating method of the reboiler 14 include a heating method using an electric heater and a heating method using another warm fluid through a heat exchanger, but are not limited thereto. Although not shown in FIG. 1, the distillation column 13 may be equipped with a condenser that cools the rising gas into a descending liquid. Further, the neon purification apparatus 100 of the present embodiment includes a distillation column gas reflux line 107 that can introduce the distillation column gas containing helium exiting from the top of the distillation column 13 into the buffer container 1. Since this distillation column gas contains 80 vol% or more of neon, the recovery rate of neon can be improved by refluxing the distillation column gas.

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

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

[0044]

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

[0046] Next, the raw material gas in the buffer container 1 was introduced into the compressor 2. In the compressor 2, the raw material gas was compressed to 30 bar. Oxygen gas was added to the compressed raw material gas at a flow rate of 0.1 Nm ３ / h. Then, the raw material gas to which oxygen gas was added was supplied to the hydrogen oxidation unit 3. The hydrogen oxidation unit 3 was heated by an external heater. In the hydrogen oxidation unit 3, hydrogen and oxygen in the raw material gas were reacted to be converted into water. The raw material gas discharged from the hydrogen oxidation unit 3 passed through the cooler 4 and then was introduced into the normal temperature gas-liquid separator 5. Most of the moisture in the raw material gas was removed by the normal temperature gas-liquid separator 5. The raw material gas from which moisture was removed in the normal temperature gas-liquid separator 5 was introduced into the moisture removal unit 6. By the moisture removal unit 6, the concentrations of moisture and carbon dioxide in the raw material gas were each less than 10 volppb. The moisture removal unit 6 is a two-column TSA method, and while the adsorption process is being performed in one adsorption tower, the regeneration process is being performed in the other adsorption tower. The adsorption process and the regeneration process were alternately switched between the two adsorption towers. Each adsorption tower was filled with zeolite. Through the dry gas supply line 103 from outside the system of the neon purification device 100, dry nitrogen gas was supplied to the moisture removal unit 6 as the regeneration gas at a flow rate of 1.5 Nm ３ / h. Specifically, this regeneration gas was introduced into the adsorption tower of the moisture removal unit 6 in a state heated to 200°C.

[0047] The nitrogen concentration of the raw material gas from which moisture was removed in the moisture removal section 6 was 25 vol%, the argon concentration was 100 vol ppm, and the oxygen concentration was 10 vol ppm. This raw material gas was introduced into the first adsorption section 7. The first adsorption section 7 is a four-column VPSA system, where while the adsorption process was being performed in one adsorption column, a regeneration process was being performed in another adsorption column, and a pressure equalization process was being performed in the remaining two adsorption columns (although only two columns are shown in Figure 1, Example 1 uses a four-column system). Zeolite was packed into each adsorption column as an adsorbent. In Example 1, the pressure was reduced to 10 bar by two pressure equalization processes, followed by depressurization, and then the system was evacuated to 0.05 bar in a vacuum evacuation process. The gas discharged in the depressurization and vacuum evacuation processes was released outside the neon purification apparatus 100 system. In the exhaust gas regeneration process, the separated gas, mainly composed of helium removed from the raw material gas in the helium removal section 11, is supplied through the rinse gas supply line 105 at a rate of 1.6 Nm³. ３ The rinse gas was supplied to the first adsorption unit 7 at a flow rate of / h. The mixed gas, which was a mixture of the rinse gas supplied to the first adsorption unit 7 and desorbed gas such as nitrogen desorbed from the first adsorption unit 7, was discharged outside the system via the exhaust line 106.

[0048] After nitrogen, argon, and oxygen were adsorbed and removed in the first adsorption unit 7, the concentrations of nitrogen, argon, and oxygen in the raw material gas were each 10 vol ppm or less. This raw material gas was introduced into the first heat exchanger 8 in the cold box 20. Next, the raw material gas, cooled to 68 K in the first heat exchanger 8, was introduced into the second adsorption unit 9. After nitrogen, argon, and oxygen were adsorbed and removed in the second adsorption unit 9, the concentrations of nitrogen, argon, and oxygen in the raw material gas were each less than 10 vol ppb. Zeolite was packed into this second adsorption unit 9. The required volume of zeolite to continuously remove nitrogen, argon, and oxygen for one year is 20 L. After one year of continuous operation, with the second adsorption unit 9 heated to room temperature, a gas that does not contain nitrogen, argon, and oxygen is circulated through the second adsorption unit 9 to desorb nitrogen, argon, and oxygen from the second adsorption unit 9. Subsequently, by cooling the second adsorption unit 9, the second adsorption unit 9 can again remove nitrogen, argon, and oxygen in the same manner.

[0049] Next, the raw material gas from which nitrogen, argon, and oxygen had been adsorbed and removed in the second adsorption section 9 was introduced into the second heat exchanger 10. Then, the raw material gas cooled to 31K in the second heat exchanger 10 was introduced into the helium removal section 11. The separated gas removed from the raw material gas in the helium removal section 11 consists of neon and helium, and contains 85 vol% or more of helium. As described above, this separated gas was supplied to the first adsorption section 7 as rinse gas through the rinse gas supply line 105. Next, the liquefied gas on the liquid phase side of the helium removal section 11 was reduced to 3 bar by the expansion valve 12 and then introduced into the top side of the distillation column 13. Neon and helium in the raw material gas were separated by distillation through gas-liquid contact in the distillation column 13. The distillation column 13 is a packed column filled with irregular packing material. A reboiler 14 is attached to the distillation column 13. The reboiler 14 employs an electric heater type. The top gas of the distillation column 13 contained neon, and therefore refluxed to the buffer container 1 via the distillation column gas reflux line 107. Neon was concentrated at the bottom of the distillation column 13. This concentrated neon was extracted as product neon via the compressor 15. The neon concentration of the product neon was 99.99 vol% or higher. The flow rate of the product neon was 4.1 Nm³. ３ It was / h.

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

[0051] <Comparative Example 1> In Comparative Example 1, neon purification was performed using the neon purification apparatus 100 shown in Figure 1, similar to Example 1. Comparative Example 1 differs from Example 1 in that the first adsorption unit 7 was operated under operating conditions that removed only nitrogen from the raw material gas; other conditions and procedures are the same. Therefore, this section will mainly explain the differences from Example 1.

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

[0053] By comparing Example 1 with Comparative Example 1, it was confirmed that removing argon and oxygen in addition to nitrogen in the first adsorption unit 7 reduces the operating power of the cryogenic refrigerator 21 and improves the efficiency of neon purification.

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

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

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

Claims

1. A neon purification apparatus comprising: a first adsorption unit for adsorbing and removing nitrogen and argon from a raw material gas; a cooling unit for cooling the raw material gas from which nitrogen and argon have been adsorbed and removed in the first adsorption unit to obtain a cooling gas; and a second adsorption unit for adsorbing and removing one or both of nitrogen and argon from the cooling gas.

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

3. The neon purification apparatus according to claim 1 or 2, wherein the concentration of argon in the raw material gas after nitrogen and argon have been adsorbed and removed in the first adsorption unit is 10 vol ppm or less.

4. The neon purification apparatus according to claim 1 or 2, wherein oxygen gas containing argon is added to the raw material gas before it is supplied to the first adsorption unit.

5. A method for purifying neon using the neon purification apparatus described in claim 1 or 2.

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