Neon purification apparatus and neon purification method

Abstract

The present invention provides a neon purification apparatus and neon purification method that can improve the efficiency of neon purification. [Solution] The neon purification apparatus 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 in 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

Technical Field

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

Background Art

[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 cryo-adsorption, and a distillation unit.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[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.

Means for Solving the Problems

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

[0008] A neon purification apparatus as one embodiment of the present invention is (2) The neon purification apparatus described in (1) above, 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.

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

[0010] A neon purification apparatus as one embodiment of the present invention is (4) Before being supplied to the first adsorption unit, oxygen gas containing argon is added to the raw material gas. The neon refining apparatus is one of the neon refining apparatuses described in any one of the above (1) to (3).

[0011] A neon purification apparatus as one embodiment of the present invention is (5) This is a neon purification method performed using a neon purification apparatus described in any one of (1) to (4) above. [Effects of the Invention]

[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. [Brief explanation of the drawing]

[0013] [Figure 1]It is a diagram showing a neon purification device according to an embodiment of the present invention.

Embodiments for Carrying out the Invention

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

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

[0016] The buffer container 1 receives the raw neon gas supplied from the raw neon gas supply line 101 and the reflux gas refluxed in a part of the process of the neon purification device 100, and stores and holds the mixture thereof as a raw material gas. Examples of the 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. Note that the buffer container 1 may receive no reflux gas and store only the raw neon gas as the raw material gas. Further, the neon purification device 100 may not include the buffer container 1. In this case, the raw neon gas and the reflux gas may be mixed, for example, in the raw neon gas supply line 101 to be used as the 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 raw material gas pressurized by the compressor 2 is supplied to the hydrogen oxidation unit 3. The raw material gas supplied to the hydrogen oxidation unit 3 may be heated by a heater before being supplied to the hydrogen oxidation unit 3, or may be heated by a heater provided in the hydrogen oxidation unit 3 after being supplied to the hydrogen oxidation unit 3. Also, before being supplied to the hydrogen oxidation unit 3, oxygen gas is added to the raw material gas. As a result, hydrogen and oxygen in the raw material gas react in the hydrogen oxidation unit 3, and water is generated by the oxidation of hydrogen. Although details will be described later, the oxygen gas contains argon in addition to oxygen. The hydrogen oxidation unit 3 includes a catalyst that promotes the reaction between hydrogen and oxygen. The hydrogen oxidation unit 3 of the present embodiment includes a hydrogen oxidation tower, and the catalyst is filled in the hydrogen oxidation tower. Examples of the catalyst include, but are not limited to, platinum, palladium, and copper. The raw material gas whose temperature has risen due to the reaction heat of the catalytic reaction in the hydrogen oxidation unit 3 is introduced into the cooler 4 and cooled to room temperature or lower. The raw material gas cooled by the cooler 4 is introduced into the normal temperature gas-liquid separator 5. As a result, the water condensed by the cooling in the cooler 4 is separated to the liquid phase side, and components other than that are separated to the gas phase side.

[0018] The raw material gas separated to the gas phase side in the normal 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 by the temperature swing adsorption (TSA: Thermal Swing Adsorption) method (hereinafter simply referred to as the "TSA method") that repeats adsorption and regeneration by a temperature difference.

[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 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, it is a general industrial argon produced by liquefying and distilling air. The oxygen gas used in the process contains approximately 2000 to 4000 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 section 3 and the moisture removal section 6. Therefore, the raw material gas is supplied to the first adsorption section 7 containing argon. The concentration of argon in the raw material gas supplied to the first adsorption section 7 depends on the argon concentration in the oxygen gas and the amount of oxygen gas added to the raw material gas, 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 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, which includes 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] Furthermore, 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 was 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 based on the TSA method, or on a pressure swing adsorption (PSA) method (hereinafter simply referred to as the "PSA method") that 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 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 within the range of 5 to 40°C.

[0033] In the neon purification apparatus 100, the duration of each process and the amount of adsorbent are adjusted 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 section 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, it is separated from the raw material gas in the helium removal section 11 described later. The removed separated gas is supplied to the first adsorption unit 7 as rinse gas through the rinse gas supply line 105. The separated gas, which is separated and removed from the raw material gas in the helium removal unit 11, mainly consists of helium. Therefore, by using this separated gas as 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 system 100, can also be supplied to the first adsorption unit 7 as 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 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, for example, between 44K and 100K. In this specification, 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 the "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 / or argon 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. In Figure 1, the circulating refrigerant from the cryogenic refrigerator 21 is shown circulating 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 from 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. In addition, separate refrigerators 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 in the helium removal section 11, is introduced into the expansion valve 12. This separation liquid is depressurized by Joule-Thomson expansion in the expansion valve 12 and then introduced into the top of the distillation column 13. In the distillation column 13, helium is further removed from the raw material gas, i.e., the separation liquid, from which the separation gas mainly composed of helium has been separated in the helium removal section 11. Specifically, when the raw material gas is supplied to the distillation column 13, neon gas containing helium is concentrated at the top of the column, and high-purity neon of 99 vol% or more is concentrated at the bottom of the column. This high-purity neon is extracted from the bottom of the distillation column 13 and compressed by the compressor 15 to be extracted as product neon. If the product neon is to be extracted from the distillation column 13 in liquid form, a liquid transfer pump may be used instead of the compressor 15. Also, the product neon may be extracted without using the compressor 15. The distillation column 13 is equipped with a reboiler 14 that vaporizes the descending liquid to produce rising gas. The distillation column 13 may be a regularly packed column, a randomly packed column, or a tray column. The heating method for the reboiler 14 may include, but is not limited to, a heating method using an electric heater or a heating method using another hot fluid via a heat exchanger. Although not shown in Figure 1, the distillation column 13 may be equipped with a condenser that cools the rising gas to produce a falling liquid. Furthermore, the neon purification apparatus 100 of this embodiment is equipped with a distillation column gas reflux line 107 that can introduce the helium-containing distillation column gas 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 a neon purification apparatus 100, as one 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, the first adsorption unit 7 can remove 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, thereby suppressing an increase in the operating power of the cryogenic refrigerator 21. As a result, the efficiency of neon purification can be improved. [Examples]

[0043] Examples using the neon purification apparatus according to the present invention are described below.

[0044] [Table 1]

[0045] <Example 1> In Example 1, neon purification was performed using the neon purification apparatus 100 shown in Figure 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 are shown in Table 1.

[0046] Next, the raw material gas from buffer container 1 was introduced into compressor 2. Compressor 2 compressed the raw material gas to 30 bar. 0.1 Nm³ was added to the compressed raw material gas. 3Oxygen gas was added at a flow rate of 1 / h. Next, the oxygenated raw material gas 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, the hydrogen and oxygen in the raw material gas reacted to convert them into water. The raw material gas discharged from the hydrogen oxidation unit 3 passed through the cooler 4 and was then introduced to the ambient temperature gas-liquid separator 5. The ambient temperature gas-liquid separator 5 removed most of the moisture from the raw material gas. The raw material gas from which moisture had been removed in the ambient temperature gas-liquid separator 5 was introduced to the moisture removal unit 6. In the moisture removal unit 6, the concentrations of moisture and carbon dioxide in the raw material gas were reduced to less than 10 vol ppb each. The moisture removal unit 6 is a two-tower TSA system, where the adsorption process is performed in one adsorption tower while the regeneration process is performed in the other adsorption tower. The adsorption and regeneration processes were alternately switched between the two adsorption towers. Zeolite was packed into each adsorption tower. From outside the neon purification apparatus 100, dry nitrogen gas is supplied via the dry gas supply line 103 as the regeneration gas for the moisture removal section 6, at a rate of 1.5 Nm³. 3 The regenerated gas was supplied to the moisture removal section 6 at a flow rate of / h. Specifically, this regenerated gas was heated to 200°C before being introduced into the adsorption tower of the moisture removal section 6.

[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-tower VPSA system, where while the adsorption process was being performed in one adsorption tower, a regeneration process was being performed in another adsorption tower, and a pressure equalization process was being performed in the remaining two adsorption towers (although only two towers are shown in Figure 1, Example 1 uses a four-tower system). Zeolite was packed as the adsorbent in each adsorption tower. 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 regeneration process, the separated gas, mainly composed of helium separated and removed from the raw material gas in the helium removal section 11, was supplied through the rinse gas supply line 105 at 1.6 Nm³. 3The 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 gases 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 section 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 then cold... The raw material gas was introduced into the first heat exchanger 8 in box 20. Next, the raw material gas, cooled to 68K 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. The second adsorption unit 9 was filled with zeolite. 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 same removal of nitrogen, argon, and oxygen can be performed again by the second adsorption unit 9.

[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, containing 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 distillation column 13 contained neon, and therefore refluxed to buffer container 1 via the distillation column gas reflux line 107. Neon was concentrated at the bottom of distillation column 13. This concentrated neon was extracted as product neon via compressor 15. The neon concentration of the product neon was 99.99 vol% or 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 describe 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 section 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 as long as they do not depart from the scope of the claims. [Industrial applicability]

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

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

Claims

1. A first adsorption unit that adsorbs and removes nitrogen and argon from the raw material gas, A cooling unit cools the raw material gas from which nitrogen and argon have been adsorbed and removed in the first adsorption unit to obtain a cooling gas, A neon purification apparatus comprising a second adsorption unit that adsorbs and removes one or both 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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