Oxygen isotope enrichment device and oxygen isotope enrichment method

Abstract

To provide an oxygen isotope concentrator where the reduction of an oxygen treatment amount can be performed by simplifying device configuration.SOLUTION: An oxygen isotope concentrator 1 comprises: a plurality of device groups having an ozone generation device 11, a carbon tetrafluoride feeder 17, an oxygen separator 12, an ozone photolysis device 13, a collector 14 and a concentrator 15; one or more oxygen supply passages 16 introducing oxygen separated at the concentrator 15 of the kth group (1≤k≤(n-1)) to the ozone generation device 11 of the (k+1)th group; and one or more mixed gas return passages 23' by which a mixed gas of ozone separated at the concentrator 15 of any jth group (2≤j≤n) and carbon tetrafluoride is introduced to any one of the first group to the (j-1) group.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an oxygen isotope enrichment device and an oxygen isotope enrichment method. [Background technology]

[0002] Stable isotopes are generally used as tracers in the fields of natural science and medicine, but many stable isotopes have low natural abundances and require significant enrichment before use.

[0003] For example, when using stable oxygen isotopes as tracers in the fields of natural science and medicine, concentrations on the order of 100% are required. 17 O) and oxygen-18( 18 The natural abundances of 2,3,4-trimethylsilyl ...

[0004] Methods for enriching and separating oxygen isotopes are known, for example, from Patent Document 1, Patent Document 2, and Non-Patent Document 1. The separation of isotopes by photoreaction described in Patent Document 1 is characterized by a large separation factor compared to other separation methods, but the enrichment factor is only about 10 times at most, and a multi-stage process is required to achieve a high enrichment factor.

[0005] As such a multistage process, for example, the enrichment process disclosed in Patent Document 2 may be cascaded as disclosed in Non-Patent Document 1. Here, Fig. 3 shows the configuration of a conventional oxygen isotope enrichment apparatus equipped with a multistage process.

[0006] 3, a conventional oxygen isotope enrichment apparatus 100 includes a plurality of apparatus groups k, k+1. Specifically, each of the apparatus groups k, k+1 includes an ozone generation apparatus 11 that generates ozone (O3) from oxygen (O2), a carbon tetrafluoride supply apparatus 17 that supplies carbon tetrafluoride (CF4) to a mixture of oxygen and ozone, an oxygen separation apparatus 12 that separates oxygen from a mixture of oxygen, ozone, and carbon tetrafluoride, an ozone photolysis apparatus 13 that irradiates a mixture of ozone and carbon tetrafluoride with light to selectively decompose ozone containing a specific oxygen isotope into oxygen, and a photolysis apparatus 14 that selectively decomposes ozone containing a specific oxygen isotope into oxygen. The oxygen isotope enrichment system 100 includes a collector 14 that collects a mixed gas containing carbon fluoride and oxygen, a concentrator 15 that separates a mixed gas containing ozone, carbon tetrafluoride, and oxygen into oxygen and a mixed gas of ozone and carbon tetrafluoride and enriches oxygen isotopes in the oxygen, an ozone abatement system 18 that decomposes ozone from the mixed gas of ozone and carbon tetrafluoride to produce oxygen, and a carbon tetrafluoride separator 19 that separates carbon tetrafluoride from the mixed gas of carbon tetrafluoride and oxygen. The oxygen isotope enrichment system 100 includes an oxygen supply path 16 between the kth device group and the next k+1 device group that introduces the oxygen separated in the kth concentrator 15 into the (k+1)th ozone generator 11′. As shown in FIG. 3 , the (k+1)th device and path have the same configuration as the kth device and path, with an ' after the reference numeral.

[0007] Furthermore, the enrichment method using the conventional oxygen isotope enrichment apparatus 100 includes a plurality of process groups k, k+1. Specifically, each of the process groups k, k+1 includes an ozone generation step of generating ozone (O3) from oxygen (O2), a carbon tetrafluoride supply step of supplying carbon tetrafluoride (CF4) to a mixture of oxygen and ozone, an oxygen separation step of separating oxygen from the mixture of oxygen, ozone, and carbon tetrafluoride, an ozone photolysis step of irradiating the mixture of ozone and carbon tetrafluoride with light to selectively decompose ozone containing a specific oxygen isotope into oxygen, and a decomposition step of ozone and tetrafluoride. The method for concentrating oxygen isotopes includes a collection step of collecting a mixed gas containing ozone, carbon tetrafluoride, and oxygen, a concentration step of separating the mixed gas containing ozone, carbon tetrafluoride, and oxygen into oxygen and a mixed gas of ozone and carbon tetrafluoride and concentrating oxygen isotopes in the oxygen, an ozone abatement step of decomposing ozone from the mixed gas of ozone and carbon tetrafluoride to produce oxygen, and a carbon tetrafluoride separation step of separating carbon tetrafluoride from the mixed gas of carbon tetrafluoride and oxygen. In the method for concentrating oxygen isotopes, the oxygen separated in the k-th concentration step is introduced as a raw material into the (k+1)-th ozone generation step.

[0008] As described above, the conventional oxygen isotope enrichment apparatus 100 and enrichment method continuously perform a specific oxygen stable isotope enrichment operation.

[0009] Furthermore, in the conventional oxygen isotope enrichment apparatus 100, each of the apparatus groups k and k+1 includes an ozone removal apparatus 18, a carbon tetrafluoride separation apparatus 19, and a carbon tetrafluoride return path 20 that returns the carbon tetrafluoride separated in the carbon tetrafluoride separation apparatus 19 to the carbon tetrafluoride supply apparatus 17 of any preceding process group. The conventional oxygen isotope enrichment apparatus 100 is provided with an oxygen exhaust path 25 for discharging oxygen separated in the carbon tetrafluoride separation device 19 to the outside of the system in any step group k, and an oxygen return path 21′ for introducing oxygen separated in the carbon tetrafluoride separation device 19 into the ozone generator 11 in the preceding step group k in any step group k+1. As described above, the conventional oxygen isotope enrichment apparatus 100 and enrichment method are configured to reuse oxygen and carbon tetrafluoride. [Prior art documents] [Patent documents]

[0010] [Patent Document 1] International Publication No. 2007 / 020934 [Patent Document 2] Japanese Patent Application Laid-Open No. 2008-080200 [Non-patent literature]

[0011] [Non-Patent Document 1] Nuclear Chemical Engineering by Hiroshi Yamamoto, Akira Kanagawa, and Kunio Higashi, published in 1976 by Nikkan Kogyo Shimbun Summary of the Invention [Problem to be solved by the invention]

[0012] However, in the conventional oxygen isotope enrichment apparatus 100 and enrichment method as shown in FIG. 3, in order to reuse oxygen and carbon tetrafluoride, it is necessary to provide an ozone detoxification apparatus 18 and a carbon tetrafluoride separation apparatus 19 in each apparatus group, and to perform an ozone detoxification step and a carbon tetrafluoride separation step in each process group, respectively, which poses a problem of complex apparatus configuration and number of processes.

[0013] Furthermore, the conventional oxygen isotope enrichment apparatus 100 and enrichment method have had a problem in that the amount of oxygen processed increases in the ozone generation apparatus 11 and the ozone generation step in any device group and process group.

[0014] The present invention has been made in consideration of the above circumstances, and an object of the present invention is to provide an oxygen isotope enrichment device and an oxygen isotope enrichment method that simplify the device configuration and processing steps and enable a reduction in the amount of oxygen processed in a multi-stage process in which stable oxygen isotope enrichment processes are configured in a cascade. [Means for solving the problem]

[0015] In order to solve the above problems, the present invention has the following configuration. [1] An ozone generator for generating ozone from oxygen; a carbon tetrafluoride supply device located on the secondary side of the ozone generator and supplying carbon tetrafluoride to the mixture of oxygen and ozone; an oxygen separator located on the secondary side of the carbon tetrafluoride supply device and separating oxygen from a mixture of oxygen, ozone, and carbon tetrafluoride; an ozone photolysis device located on the secondary side of the oxygen separation device, which irradiates a mixture of ozone and carbon tetrafluoride with light to selectively decompose ozone containing a specific oxygen isotope into oxygen; a collector located on the secondary side of the ozone photolysis device and configured to collect a mixed gas containing ozone, carbon tetrafluoride, and oxygen; a plurality of device groups (first group to nth group) each having an enrichment device located on the secondary side of the collection device, which separates a mixed gas containing ozone, carbon tetrafluoride, and oxygen into oxygen and a mixed gas of ozone and carbon tetrafluoride, and enriches oxygen isotopes in the oxygen; One or more oxygen supply paths for introducing oxygen separated in the kth (1≦k≦(n−1)) concentrator into the (k+1)th ozone generator; An oxygen isotope enrichment device comprising one or more mixed gas return paths for introducing a mixed gas of ozone and carbon tetrafluoride separated in any jth (2≦j≦n) group of enrichment devices into any one of the first to (j-1)th groups. [2] The oxygen isotope enrichment device according to [1], further comprising an ozone concentration measuring device located in the mixed gas return path and measuring the ozone concentration in the mixed gas return path. [3] One or more device groups, excluding any jth group (2≦j≦n), an ozone detoxification device located on the secondary side of the concentrator and configured to decompose ozone from a mixed gas of ozone and carbon tetrafluoride to generate oxygen; The oxygen isotope enrichment device according to [1] or [2], further comprising: a carbon tetrafluoride separation device located on the secondary side of the ozone detoxification device, which separates carbon tetrafluoride from a mixed gas of carbon tetrafluoride and oxygen. [4] an ozone generation step of generating ozone from oxygen; a carbon tetrafluoride supplying step of supplying carbon tetrafluoride to a mixture of unreacted oxygen and ozone; an oxygen separation step of separating oxygen from a mixture of oxygen, ozone, and carbon tetrafluoride; an ozone photolysis step in which a mixture of ozone and carbon tetrafluoride is irradiated with light to selectively decompose ozone containing a specific oxygen isotope into oxygen; a collecting step of collecting a mixed gas containing undecomposed ozone, carbon tetrafluoride, and oxygen; a concentration step of separating a mixed gas containing undecomposed ozone, carbon tetrafluoride, and oxygen into oxygen and a mixed gas of ozone and carbon tetrafluoride, and concentrating oxygen isotopes in the oxygen, The oxygen separated in the k-th group (1≦k≦(n−1)) of the concentration step is used in the (k+1)-th group of ozone generation steps, A method for enriching oxygen isotopes, wherein a mixed gas of ozone and carbon tetrafluoride separated in any jth group (2≦j≦n) of the enrichment steps is returned to any one of the first to (j-1)th groups of steps. [5] The method for enriching oxygen isotopes according to [4], wherein the ozone concentration in the mixed gas of ozone and carbon tetrafluoride separated in the enrichment step of any jth group (2≦j≦n) is monitored when the mixed gas is returned to any one of the first to (j-1)th groups of steps. [6] One or more process groups, excluding any jth group (2≦j≦n), an ozone detoxification step of generating oxygen by decomposing ozone from a mixed gas of ozone and carbon tetrafluoride after the concentration step; The method for enriching oxygen isotopes according to [4] or [5], further comprising, after the ozone removal step, a carbon tetrafluoride separation step of separating carbon tetrafluoride from a mixed gas of carbon tetrafluoride and oxygen. [Effects of the Invention]

[0016] The oxygen isotope enrichment apparatus of the present invention simplifies the apparatus configuration and enables a reduction in the amount of oxygen processed in a multi-stage process in which stable oxygen isotope enrichment processes are configured in cascade. Furthermore, the oxygen isotope enrichment method of the present invention simplifies the processing steps in a multi-stage process in which stable oxygen isotope enrichment processes are configured in a cascade, and makes it possible to reduce the amount of oxygen processed. [Brief explanation of the drawings]

[0017] [Figure 1] 1 is a system diagram showing the configuration of an oxygen isotope enrichment device according to one embodiment of the present invention. [Figure 2] 1 is a system diagram showing the configuration of an oxygen isotope enrichment device applied to an embodiment of the present invention. [Figure 3] FIG. 1 is a system diagram showing the configuration of a conventional oxygen isotope enrichment device. DETAILED DESCRIPTION OF THE INVENTION

[0018] An oxygen isotope enrichment apparatus according to an embodiment of the present invention will be described in detail below with reference to the drawings. Note that the drawings used in the following description may show characteristic portions enlarged for the sake of clarity, and the dimensional proportions of the components may not necessarily be the same as those in reality.

[0019] <Oxygen isotope enrichment device> First, an oxygen isotope enrichment apparatus according to one embodiment of the present invention will be described in detail with reference to the drawings. Fig. 1 is a system diagram showing an example of the configuration of the oxygen isotope enrichment apparatus according to this embodiment. As shown in Fig. 1, the oxygen isotope enrichment apparatus 1 of this embodiment includes a plurality of device groups (first to nth groups, where n is an integer of 2 or more). For convenience, only device group k and device group k+1 (1 ≤ k ≤ (n-1)) are shown in Fig. 1.

[0020] The device group k and the device group k+1 each include an ozone generator 11, a carbon tetrafluoride supply device 17, an oxygen separator 12, an ozone photodecomposition device 13, a collector 14, and a concentrator 15. As shown in Fig. 1, the devices and paths in the (k+1)th group that have the same configuration as the devices and paths in the kth group are marked with "'" after their reference numerals, and the description thereof will be omitted.

[0021] The ozone generator 11 generates ozone from oxygen using raw oxygen supplied from an oxygen supply source (not shown) or concentrated oxygen supplied from a group of devices in a previous stage via an oxygen supply path 16. The ozone generator 11 generates ozone from oxygen by discharging from an electrode equipped with a high-frequency power supply device or by irradiating with ultraviolet rays from a mercury lamp. The generated ozone is discharged from the ozone generator 11 as a mixture of oxygen and ozone.

[0022] The carbon tetrafluoride supplying device 17 is located on the secondary side of the ozone generator 11, and supplies carbon tetrafluoride to the mixture of oxygen and ozone discharged from the ozone generator 11. The mixture after carbon tetrafluoride has been supplied is introduced into the oxygen separation device 12 at the subsequent stage.

[0023] The oxygen separator 12 is located on the secondary side of the ozone generator 11 and the carbon tetrafluoride supply device 17, and separates oxygen from the mixture of oxygen, ozone, and carbon tetrafluoride. Specifically, the oxygen separator 12 separates oxygen by distillation or by using an adsorbent such as silica gel. The separated and recovered oxygen is returned to the upstream ozone generator 11 via path 10 for reuse.

[0024] The ozone photolysis device 13 is located on the secondary side of the oxygen separation device 12, and selectively decomposes ozone containing specific oxygen isotopes into oxygen by irradiating light onto the mixture of ozone and carbon tetrafluoride extracted from the oxygen separation device 12. Note that the ozone photolysis device 13 decomposes ozone molecules containing specific oxygen isotopes using a light source having a specific wavelength range.

[0025] Specific ozone molecules include, for example: 16 O16 O 17 O. 16 O 16 O 18 O. 16 O 17 O 17 O. 16 O 18 O 18 O. 16 O 17 O 18 O is one example.

[0026] Examples of light sources having a specific wavelength range include sunlight spectroscopy, InGaAsP-based semiconductor lasers or light-emitting diodes, AlGaInP-based semiconductor lasers or light-emitting diodes, GaAsSb-based semiconductor lasers or light-emitting diodes, CdZnTe-based semiconductor lasers or light-emitting diodes, CdZnSe-based semiconductor lasers or light-emitting diodes, and dye lasers that can be optically pumped with a mercury lamp, a YAG laser, an Ar ion laser, a Kr ion laser, or the like.

[0027] In the ozone photolysis device 13, the part where the mixture of ozone and carbon tetrafluoride flows is preferably kept at a low temperature (for example, in the range of 100 to 250 K) to suppress spontaneous decomposition of ozone.

[0028] The collector 14 is located on the secondary side of the ozone photolysis device 13 and collects the mixed gas containing ozone, carbon tetrafluoride, and oxygen that is discharged from the ozone photolysis device 13. An example of the collector 14 is a double-tube condenser that continuously liquefies and collects the mixed gas.

[0029] Concentrator 15 is located on the secondary side of collector 14, and separates the mixed gas containing ozone, carbon tetrafluoride, and oxygen discharged from collector 14 into oxygen and a mixed gas of ozone and carbon tetrafluoride, thereby concentrating oxygen isotopes in the oxygen. Specifically, concentrator 15 separates oxygen by distillation or using an adsorbent such as silica gel.

[0030] The oxygen isotope enrichment apparatus 1 of this embodiment includes a plurality of device groups (first to nth groups, n is an integer of 2 or more), and the number of device groups is preferably 2 to 10, and more preferably 2 to 5.

[0031] The oxygen isotope enrichment apparatus 1 of this embodiment also includes one or more oxygen supply paths 16 that introduce oxygen separated in the kth (1≦k≦(n−1)) enrichment apparatus 15 into the (k+1)th ozone generator 11′. This allows the oxygen isotope enrichment apparatus 1 of this embodiment to continuously perform enrichment operations for specific stable oxygen isotopes.

[0032] Furthermore, the oxygen isotope enrichment apparatus 1 of this embodiment includes one or more mixed gas return paths 23 that introduce the mixed gas of ozone and carbon tetrafluoride separated in the enrichment device 15 in any jth (2≦j≦n) device group into any of the first to (j−1)th groups that precede the jth group. Specifically, as shown in FIG. 1 , the k+1th group includes a mixed gas return path 23′ that introduces the mixed gas of ozone and carbon tetrafluoride separated in the enrichment device 15′ into the kth oxygen separation device 12.

[0033] According to the oxygen isotope enrichment apparatus 1 of this embodiment, since the mixed gas return path 23' is provided, undecomposed ozone that was not decomposed into oxygen in the (k+1)th ozone photolysis apparatus 13' can be reused as a mixed gas of ozone and carbon tetrafluoride. Therefore, oxygen generated on the secondary side of the enrichment apparatus 15' constituting the (k+1)th apparatus group is not supplied to the kth ozone generator 11, and the amount of oxygen processed in the ozone generator 11 can be reduced.

[0034] The mixed gas return path 23' is a path located between the concentrator 15' in the (k+1)th equipment group and the oxygen separator 12 in the first equipment group. Since selective decomposition of non-isotopes by ozone in the mixed gas return path 23' leads to a decrease in isotope enrichment, it is preferable to form an oxide film in advance on the inside of the piping that constitutes the mixed gas return path 23' using high-concentration ozone or the like to suppress ozone decomposition due to a metal catalytic reaction on the inner surface of the piping. Furthermore, it is preferable to maintain the mixed gas return path 23' at a low temperature (for example, in the range of 100 to 250 K) to suppress natural decomposition of ozone.

[0035] An ozone concentration measuring device 22' is located in the mixed gas return path 23' to measure the ozone concentration in the mixed gas of ozone and carbon tetrafluoride flowing through the mixed gas return path 23'. This makes it possible to monitor the ozone concentration in the mixed gas return path 23' and manage it within a safe concentration range.

[0036] The ozone concentration measuring device 22' is not particularly limited, but is preferably a device that uses light absorption such as ultraviolet spectroscopy, since ozone is not easily altered.

[0037] Furthermore, in the oxygen isotope enrichment apparatus 1 of this embodiment, one or more device groups excluding any j-th group (2≦j≦n) have an ozone detoxification device 18 and a carbon tetrafluoride separation device 19. In other words, any j-th device group (2≦j≦n) does not have an ozone detoxification device 18 or a carbon tetrafluoride separation device 19.

[0038] 1, the kth device group includes an ozone detoxification device 18 and a carbon tetrafluoride separation device 19. The k+1th device group does not include the ozone detoxification device 18 or the carbon tetrafluoride separation device 19.

[0039] The ozone detoxification device 18 is located on the secondary side of the concentrator 15 and generates oxygen by decomposing ozone from the mixed gas of ozone and carbon tetrafluoride discharged from the concentrator 15. The ozone detoxification device 18 performs ozone decomposition at room temperature. Specifically, a catalyst is used to lower the activation energy of the self-decomposition reaction of ozone, thereby decomposing the ozone.

[0040] The carbon tetrafluoride separation device 19 is located on the secondary side of the ozone abatement device 18, and separates carbon tetrafluoride from the mixed gas of carbon tetrafluoride and oxygen discharged from the ozone abatement device 18. Specifically, the carbon tetrafluoride separation device 19 separates the mixed gas of carbon tetrafluoride and oxygen into carbon tetrafluoride and oxygen by distillation or using an adsorbent such as silica gel.

[0041] The carbon tetrafluoride separated by the carbon tetrafluoride separation device 19 is returned via a path 20 to the carbon tetrafluoride supply device 17 at the previous stage for reuse. The oxygen separated by the carbon tetrafluoride separator 19 can be extracted via an oxygen exhaust line 25 .

[0042] According to the oxygen isotope enrichment apparatus 1 of this embodiment, the kth group of apparatuses has an ozone detoxification apparatus 18 and a carbon tetrafluoride separation apparatus 19, and the k+1th group of apparatuses does not have an ozone detoxification apparatus 18 or a carbon tetrafluoride separation apparatus 19, thereby simplifying the apparatus configuration.

[0043] <Method for enriching oxygen isotopes> Next, a method for concentrating oxygen isotopes according to one embodiment of the present invention will be described in detail using the above-described oxygen isotope concentrating apparatus 1 as an example. The method for enriching oxygen isotopes according to this embodiment includes a plurality of process groups (first to nth process groups, where n is an integer of 2 or more). For convenience, this embodiment shows only process group k and process group k+1 (1≦k≦(n−1)).

[0044] The process group k and the process group k+1 each include an ozone generation step, a carbon tetrafluoride supply step, an oxygen separation step, an ozone photolysis step, a collection step, and a concentration step.

[0045] In the ozone generation step, ozone is generated from oxygen in ozone generator 11 using raw oxygen supplied from an oxygen supply source (not shown) or concentrated oxygen supplied from a group of devices in a previous stage via oxygen supply path 16. The generated ozone is discharged from ozone generator 11 as a mixture of oxygen and ozone.

[0046] In the carbon tetrafluoride supply step, carbon tetrafluoride is supplied to the mixture of oxygen and ozone obtained in the ozone generation step. The mixture after the carbon tetrafluoride supply is used in the subsequent oxygen separation step.

[0047] In the oxygen separation step, oxygen is separated from the mixture of oxygen, ozone, and carbon tetrafluoride in the oxygen separator 12. The separated and recovered oxygen is reused in the preceding ozone generation step.

[0048] In the ozone photolysis step, the mixture of ozone and carbon tetrafluoride obtained in the oxygen separation step is irradiated with light in the ozone photolysis device 13, thereby selectively decomposing ozone containing a specific oxygen isotope into oxygen.

[0049] In the collection step, the collection device 14 is used to collect the mixed gas containing ozone, carbon tetrafluoride, and oxygen obtained in the ozone photolysis step.

[0050] In the enrichment step, the enrichment device 15 is used to separate the mixed gas containing ozone, carbon tetrafluoride, and oxygen obtained in the capture step into oxygen and a mixed gas of ozone and carbon tetrafluoride, and oxygen isotopes are enriched in the oxygen.

[0051] The oxygen isotope enrichment method of this embodiment includes a plurality of step groups (first to nth groups, n is an integer of 2 or more), and the number of step groups is preferably 2 to 10, and more preferably 2 to 5.

[0052] Furthermore, in the oxygen isotope enrichment method of this embodiment, oxygen separated in the kth (1≦k≦(n−1)) enrichment step is used in the ozone generation step constituting the (k+1)th step group. This allows the oxygen isotope enrichment method of this embodiment to continuously carry out enrichment operations of specific stable oxygen isotopes.

[0053] Furthermore, in the oxygen isotope enrichment method of this embodiment, in any jth (2≦j≦n) process group, the mixed gas of ozone and carbon tetrafluoride separated in the enrichment step is returned to any one of the 1st to (j−1)th process groups that precede the jth process group. Specifically, in the k+1th process group, the mixed gas of ozone and carbon tetrafluoride separated in the enrichment step is introduced into the kth oxygen separation step.

[0054] According to the oxygen isotope enrichment method of this embodiment, undecomposed ozone that was not decomposed into oxygen in the (k+1)th ozone photolysis step can be reused as a mixed gas of ozone and carbon tetrafluoride. Therefore, oxygen generated on the secondary side of the enrichment step constituting the (k+1)th process group is not used in the kth ozone generation step, and the amount of oxygen processed in the ozone generation step can be reduced.

[0055] In the oxygen isotope enrichment method of this embodiment, when a mixed gas of ozone and carbon tetrafluoride separated in an enrichment step of any jth group (2≦j≦n) is returned to any one of the first to (j−1)th groups of steps, the ozone concentration in the mixed gas is monitored.

[0056] The ozone concentration can be monitored as needed. For example, when the oxygen isotope enrichment apparatus 1 shown in FIG. 1 is operating steadily, monitoring may be performed at regular intervals. Furthermore, for example, when the apparatus is started up, when the apparatus is not in a stable state, or when the operating conditions of the apparatus are changed, the ozone concentration may be monitored continuously.

[0057] Furthermore, if the ozone concentration exceeds a predetermined value, the ozone concentration can be reduced by introducing other fluids in the oxygen isotope enrichment device 1 into the mixed gas return path 23' to dilute the ozone in the path.

[0058] Furthermore, in the oxygen isotope enrichment method of this embodiment, one or more process groups, excluding any jth group (2≦j≦n), have an ozone abatement step and a carbon tetrafluoride separation step. In other words, any jth group (2≦j≦n) does not have an ozone abatement step and a carbon tetrafluoride separation step.

[0059] Specifically, the kth process group includes an ozone abatement step and a carbon tetrafluoride separation step, and the k+1th process group does not include an ozone abatement step or a carbon tetrafluoride separation step.

[0060] In the ozone detoxification step, the ozone detoxification device 18 is used to decompose ozone from the mixed gas of ozone and carbon tetrafluoride obtained in the concentration step to produce oxygen.

[0061] In the carbon tetrafluoride separation step, carbon tetrafluoride is separated from the mixed gas of carbon tetrafluoride and oxygen obtained in the ozone abatement step using a carbon tetrafluoride separation device 19. Specifically, in the carbon tetrafluoride separation step, the mixed gas of carbon tetrafluoride and oxygen is separated into carbon tetrafluoride and oxygen.

[0062] The carbon tetrafluoride separated in the carbon tetrafluoride separation step is returned to the carbon tetrafluoride supply device 17 in the preceding stage via a path 20 and reused in the carbon tetrafluoride supply step. In addition, the oxygen separated in the carbon tetrafluoride separation step can be taken out via the oxygen exhaust line 25 .

[0063] According to the oxygen isotope enrichment method of this embodiment, the kth process group has an ozone detoxification step and a carbon tetrafluoride separation step, and the k+1th process group does not have an ozone detoxification step or a carbon tetrafluoride separation step, so the process can be simplified.

[0064] The technical scope of the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention. [Example]

[0065] The effects of the present invention will be explained below using examples, but the present invention is not limited to the configurations of the examples.

[0066] <Example> As the oxygen isotope enrichment apparatus of the present invention, an oxygen isotope enrichment apparatus 51 shown in Fig. 2 was used. The oxygen isotope enrichment apparatus 51 shows a configuration in which two device groups (first group and second group) are used in the oxygen isotope enrichment apparatus 1 shown in Fig. 1.

[0067] (Device configuration) The oxygen isotope enrichment device 51 has the following configuration. Ozone generator 11: Generates ozone from raw oxygen. Oxygen supply path 16: Located between the first group of concentrators 15 and the second group of ozone generators 11'. Concentrated oxygen outlet path 24': connected to the second group of concentrators 15'. Oxygen exhaust line 25: connected to the first group of carbon tetrafluoride separators 19. Mixed gas return line 23': Located between the second group concentrator 15' and the first group oxygen separator 12.

[0068] (Ozone photolysis conditions) Ozone photolysis device 13, 13': specific ozone molecules ( 16 O 16 O 17 O) is decomposed. Laser light: Laser light (992 nm) was used from an external cavity laser (manufactured by Sacher Lasertechnik, "TEC-320").

[0069] When ozone is irradiated with laser light, it is separated into one oxygen molecule and one oxygen atom, as shown in the following formula (1).

[0070]

number

[0071] The oxygen atoms generated in the reaction of the above formula (1) gain energy and decompose some of the surrounding ozone molecules as shown in formula (2), where n is the entrainment coefficient described in the prior art document (JP 2017-223547 A).

[0072]

number

[0073] In this example, the entrainment coefficient was set to n = 5. Meanwhile, non-selective decomposition of ozone by heat (hereinafter referred to as thermal decomposition) also occurs simultaneously, unrelated to ozone photolysis. The amount of oxygen molecules generated by thermal decomposition of ozone was calculated assuming that it is proportional to the flow rate of ozone introduced into the ozone photolysis device 13. After the start-up of the apparatus, when the "mixed gas return line 23'" is not in use, in a steady state, the supply amount of raw oxygen and the amount of ozone introduced into the ozone photolysis apparatus 13 are equal in terms of the number of oxygen atoms. In other words, it can be said that the amount of oxygen molecules generated by the thermal decomposition of ozone is proportional to the flow rate of the raw oxygen.

[0074] In the ozone photolysis devices 13 and 13′, the target ozone molecules ( 16 O 16 O 17 The decomposition rate of 0) was set at 50%.

[0075] In the first group of ozone photolysis devices 13, the laser decomposition amount was 7.63 × 10 -8 (mol / s), and the amount of thermal decomposition was 8.96×10 -7 (mol / s) (prior art document: same conditions as in JP 2017-223547 A).

[0076] Laser decomposition amount: 7.63 x 10 -8 (mol / s) and the laser decomposition rate: 50%, the flow rate of the raw material oxygen is 6.36 × 10 -8 (mol / s).

[0077] From the above conditions, the flow rate of each group in the oxygen isotope enrichment device 51 of the embodiment and the oxygen 17( 17 The concentration of 0) is calculated as shown in Table 1 below.

[0078] [Table 1]

[0079] As shown in Table 1, according to the oxygen isotope enrichment device 51, the first group of ozone generators 11: 17 When raw oxygen with an O concentration of 0.200 (atom%) is introduced, it is enriched to 0.624 (atom%) in the first group and to 1.67 (atom%) in the second group.

[0080] As described above, the oxygen isotope enrichment apparatus (enrichment method) 51 of the embodiment is configured to include multiple groups of devices (groups of processes), and it has been shown that even when the isotope components to be enriched in the raw oxygen are dilute, enrichment to the order of % is possible.

[0081] Furthermore, according to the oxygen isotope enrichment device (enrichment method) 51 shown in FIG. 2, the ozone detoxification device and carbon tetrafluoride separation device can be omitted in the second group. It is possible to reduce the amount of oxygen processed by the ozone generator 11 in the first group by the amount of ozone returned by the mixed gas return path 23' provided in the second group. Here, the amount of oxygen that can be reduced is calculated using the following formula (3).

[0082]

number

[0083] As described above, according to the oxygen isotope enrichment device (enrichment method) 51 shown in FIG. 2, by directly reusing undecomposed ozone in the second group of ozone photolysis devices 13′, the oxygen processing amount in the first group of ozone generation devices 11 can be increased to 5.08 (m 3) per year. 3 ) can be reduced. [Explanation of symbols]

[0084] 1, 51 Concentrator Routes 10 and 20 11, 11' Ozone generator 12, 12' Oxygen Separator 13, 13' Ozone photolysis device 14, 14' collection device 15, 15' concentrator 16 Oxygen supply pathway 17, 17' Carbon tetrafluoride supply device 18 Ozone removal equipment 19 Carbon tetrafluoride separator 21' Oxygen return route 22' Ozone concentration measuring device 23' Mixed gas return route 24' Concentrated oxygen delivery route 25 Oxygen exhaust route

Claims

1. an ozone generator for generating ozone from oxygen; a carbon tetrafluoride supply device located on the secondary side of the ozone generator and supplying carbon tetrafluoride to the mixture of oxygen and ozone; an oxygen separator located on the secondary side of the carbon tetrafluoride supply device and separating oxygen from a mixture of oxygen, ozone, and carbon tetrafluoride; an ozone photolysis device located on the secondary side of the oxygen separation device, which irradiates a mixture of ozone and carbon tetrafluoride with light to selectively decompose ozone containing a specific oxygen isotope into oxygen; a collector located on the secondary side of the ozone photolysis device and configured to collect a mixed gas containing ozone, carbon tetrafluoride, and oxygen; a plurality of device groups (first group to nth group) each having an enrichment device located on the secondary side of the collection device, which separates a mixed gas containing ozone, carbon tetrafluoride, and oxygen into oxygen and a mixed gas of ozone and carbon tetrafluoride, and enriches oxygen isotopes in the oxygen; one or more oxygen supply paths for introducing oxygen separated in the kth (1≦k≦(n−1)) concentrator into the (k+1)th ozone generator; and one or more mixed gas return paths for introducing a mixed gas of ozone and carbon tetrafluoride separated in any jth group (2≦j≦n) of the concentrating devices into any one of the first group to the (j-1)th group.

2. 2. The oxygen isotope enrichment apparatus according to claim 1, further comprising an ozone concentration measuring device located in the mixed gas return path and measuring an ozone concentration in the mixed gas return path.

3. One or more device groups excluding any j-th group (2≦j≦n) an ozone detoxification device located on the secondary side of the concentrator and configured to decompose ozone from a mixed gas of ozone and carbon tetrafluoride to generate oxygen; 3. The oxygen isotope enrichment apparatus according to claim 1, further comprising: a carbon tetrafluoride separation device located on the secondary side of the ozone detoxification device, which separates carbon tetrafluoride from a mixed gas of carbon tetrafluoride and oxygen.

4. an ozone generating step of generating ozone from oxygen; a carbon tetrafluoride supplying step of supplying carbon tetrafluoride to a mixture of unreacted oxygen and ozone; an oxygen separation step of separating oxygen from a mixture of oxygen, ozone, and carbon tetrafluoride; an ozone photolysis step in which a mixture of ozone and carbon tetrafluoride is irradiated with light to selectively decompose ozone containing a specific oxygen isotope into oxygen; a collecting step of collecting a mixed gas containing undecomposed ozone, carbon tetrafluoride, and oxygen; a concentration step of separating a mixed gas containing undecomposed ozone, carbon tetrafluoride, and oxygen into oxygen and a mixed gas of ozone and carbon tetrafluoride, and enriching oxygen isotopes in the oxygen, The oxygen separated in the kth group (1≦k≦(n−1)) of the concentration step is used in the (k+1)th group of ozone generation steps, A method for enriching oxygen isotopes, wherein a mixed gas of ozone and carbon tetrafluoride separated in the enrichment step of any jth group (2≦j≦n) is returned to any one of the first to (j−1)th groups of steps.

5. 5. The method for enriching oxygen isotopes according to claim 4, wherein the ozone concentration in the mixed gas of ozone and carbon tetrafluoride separated in the enrichment step of any j-th group (2≦j≦n) is monitored when the mixed gas is returned to any one of the first to (j−1)-th groups.

6. One or more process groups excluding any jth group (2≦j≦n) an ozone detoxification step of generating oxygen by decomposing ozone from a mixed gas of ozone and carbon tetrafluoride after the concentration step; 6. The method for enriching oxygen isotopes according to claim 4, further comprising, after the ozone removal step, a carbon tetrafluoride separation step of separating carbon tetrafluoride from the mixed gas of carbon tetrafluoride and oxygen.

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