Stabilized isotope concentration device

Abstract

To provide a stable isotope concentrator that has high energy efficiency and can reduce the equipment cost.SOLUTION: A stable isotope concentrator 100 comprises a group of distillation columns in which a plurality of distillation columns are connected in a cascade; wherein the group of distillation columns has a shelf column group consisting of one or more shelf columns and a filled column group consisting of one or more filled columns; and wherein the filled column group is positioned on a secondary side of the shelf column group.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a stable isotope enrichment device. [Background technology]

[0002] Known methods for separating stable isotopes that exist only in extremely small amounts in nature include thermal diffusion separation, centrifugation, laser separation, chemical exchange separation, distillation separation, etc. Among these separation methods, distillation separation is suitable for mass production of light elements, so for example, distillation separation of water and distillation separation of oxygen are used as industrial methods for separating stable isotopes of oxygen.

[0003] A feature of the method of separating stable isotopes by distillation is that, because the separation factor is extremely close to 1, several thousand theoretical plates are required to obtain a high concentration of stable isotopes. However, since there is a limit to the height of the distillation tower, it is necessary to divide the distillation tower into several towers and connect these several divided distillation towers in series (hereinafter referred to as "cascade connection").

[0004] Distillation towers are mainly classified into two types: distillation towers with trays (hereinafter referred to as "tray towers") and distillation towers packed with packings (hereinafter referred to as "packed towers"). Furthermore, there are two types of packed towers: structured packed towers packed with structured packings and randomly packed towers packed with random packings. To date, in stable isotope enrichment apparatus, randomly packed columns have often been used to reduce the height of the distillation column. In Patent Document 1, oxygen isotope enrichment is carried out by nitrogen monoxide distillation using a randomly packed column. Randomly packed columns have high separation performance due to the large specific surface area of ​​the packing. In particular, in randomly packed columns with a small column diameter of 50 mm or less, the HETP (height equivalent to a theoretical plate) is about several tens of mm (Non-Patent Document 1). Here, HETP is an index that indicates the distillation performance of the packing, and the smaller the HETP value, the better the separation performance.

[0005] In the enrichment of stable isotopes using a distillation column, in order to increase the amount of stable isotope produced, it is necessary to increase the diameter of the distillation column. However, in a randomly packed column, when a column with a large diameter is packed with small particle size packing, the pressure loss becomes very large and the gas-liquid flow is easily biased. Therefore, in general, there is a limit to the ratio of the column diameter of the randomly packed column to the particle size of the packing. As a result, the larger the column diameter of the randomly packed column, the smaller the specific surface area of ​​the packing and the higher the HETP. Non-Patent Document 2 describes the HETP data of various randomly packed materials, and when the column diameter is 50 mm, the HETP is 15 to 60 mm, when the column diameter is 108 mm, the HETP is around 100 mm, and when the column diameter is 208 mm, the HETP is 100 mm or more (specifically, about 150 mm to 200 mm).

[0006] On the other hand, as a method for increasing the column diameter while maintaining the HETP, there is a method of dividing one distillation column into several columns and connecting them in parallel (Non-Patent Document 3). However, a disadvantage of this method is that it is necessary to install either a condenser or a reboiler for each distillation column connected in parallel. Therefore, there is a problem that the increase in the number of condensers or reboilers increases the equipment cost and the complexity of operation and management.

[0007] For the above reasons, there is a limit to the number of distillation columns that can be connected in parallel, so in reality, it is necessary to design the equipment so that the diameter of each column is larger, even if this means a larger HETP. Therefore, when increasing production volume with a stable isotope enrichment system using a randomly packed column, the diameter of each column becomes larger and the number of distillation columns required also increases, resulting in poor energy efficiency.

[0008] In addition, randomly packed columns have the characteristic of having a large hold-up volume due to the large specific surface area of ​​the packing. It is known that the start-up operation time, which is the time from the start-up of the equipment to the start of product extraction, is long in the separation of stable isotopes by distillation, and the hold-up volume is a parameter that affects the start-up operation time. Therefore, when a randomly packed column is used, there is also the issue that the start-up operation time is long, resulting in high running costs. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] Japanese Patent Application Publication No. 7-148419 [Non-patent literature]

[0010] [Non-Patent Document 1] BM Andreev, EP Magomedbekov, AA Raitman, MB Pozenkevich, Yu.A. Sakharovsky and AV Khoroshilov, “Separation of istopes of biogenic elements in two-phase systems”, 2007 [Non-Patent Document 2] Tohtoken Co., Ltd., TOWER PACKINGS Catalog, No.3 [Non-Patent Document 3] BBMcInter, “Separation Science and Technology”, 15th edition, (3), 1980, p491-508 Summary of the Invention [Problem to be solved by the invention]

[0011] The present invention has been made in consideration of the above problems, and an object of the present invention is to provide a stable isotope enrichment apparatus that is highly energy efficient and can reduce equipment costs. [Means for solving the problem]

[0012] In order to achieve the above object, the present invention employs the following configuration. [1] A stable isotope enrichment apparatus for enriching stable isotopes by distillation, comprising: A distillation column group in which a plurality of distillation columns are cascaded, The distillation column group includes: A plate tower group consisting of one or more plate towers; A packed tower group consisting of one or more packed towers, A stable isotope enrichment apparatus, wherein the group of packed towers is located on the secondary side of the group of plate towers. [2] The stable isotope enrichment apparatus according to [1], wherein all of the packed towers in the group of packed towers are randomly packed towers. [3] The group of packed columns includes one or more structured packed columns and one or more random packed columns, A stable isotope enrichment apparatus according to [1], wherein one or more random packed columns are located on the secondary side of one or more structured packed columns. [4] The group of packed columns includes one or more structured packed columns and one or more random packed columns, A stable isotope enrichment apparatus according to [1], wherein one or more structured packed columns are located on the secondary side of one or more random packed columns. [5] Among the distillation columns, A stable isotope enrichment apparatus according to any one of [1] to [4], wherein the distillation column to which the raw material is supplied is a plate column. [6] The randomly packed column is The stable isotope enrichment apparatus according to any one of [2] to [5], wherein the number of the randomly packed columns connected in parallel is 20 or less. [7] A stable isotope enrichment apparatus according to any one of [2] to [6], wherein the column diameter of the randomly packed column is 200 mm or less. Effect of the Invention

[0013] The stable isotope enrichment device of the present invention has high energy efficiency and can reduce equipment costs. [Brief description of the drawings]

[0014] [Figure 1] 1 is a system diagram showing a main part of a stable isotope enrichment device according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a system diagram showing the main parts of the stable oxygen isotope enrichment device used in Example 1. [Diagram 3] FIG. 2 is a system diagram showing the main parts of the stable oxygen isotope enrichment apparatus used in Comparative Example 1. [Figure 4] FIG. 1 is a system diagram showing the main parts of a stable oxygen isotope enrichment apparatus used in Example 2. [Diagram 5] FIG. 1 is a system diagram showing the main parts of a stable oxygen isotope enrichment apparatus used in Example 3. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the accompanying drawings showing embodiments. In addition, the drawings used in the following description may show characteristic parts in an enlarged scale for convenience in order to make the features easier to understand, and the dimensional ratios of each component may not necessarily be the same as the actual ones.

[0016] <Stable isotope concentrator> FIG. 1 is a system diagram showing the main parts of a stable isotope enrichment device according to an embodiment of the present invention. The stable isotope enrichment apparatus 100 of this embodiment includes a distillation column group in which a plurality of distillation columns are cascade-connected, a plurality of condensers 21, a plurality of reboilers 22, a raw material feed line 30, and a product line 31.

[0017] Hereinafter, the nth distillation tower from the upstream end of the group of distillation towers will be referred to as the nth distillation tower. The first distillation column 1 to the n-th distillation column n are connected in cascade in the order of the column numbers. The first distillation column 1 to the nth distillation column n are configured to distill cooled stable isotopes at low temperatures, thereby concentrating stable isotopes with low boiling points at the top of the column and stable isotopes with high boiling points at the bottom of the column. Among the first distillation column 1 to the n-th distillation column n, the first distillation column 1 to which the raw material is supplied has the largest column diameter, and the column diameter gradually decreases toward the end.

[0018] The first distillation column 1 to the j-1st distillation column j-1 are each plate columns, and the jth distillation column j to the nth distillation column n are each packed columns. There are three possible configurations for the packed tower group: all randomly packed towers, a randomly packed tower on the secondary side of a structured packed tower, or a structured packed tower on the secondary side of a randomly packed tower. In addition, of the first distillation column 1 to the nth distillation column n, Figure 1 illustrates only the first distillation column 1, which is a plate column and to which the stable isotope raw material is supplied, the jth distillation column j, which is the first column to switch from a plate column to a packed column, and the nth distillation column n, which is a column from which the product is extracted. Also, for convenience of drawing, randomly packed columns connected in parallel are illustrated as one distillation column and one condenser and one reboiler each.

[0019] As explained in the Background Art section, in the case of a randomly packed column, the HETP increases as the column diameter increases. On the other hand, in the case of plate columns used in air separation plants, the plate spacing is generally about 100 mm. Therefore, when the HETP of a randomly packed column exceeds 100 mm, the height of the distillation column can be reduced by using a plate column, and as a result, the number of distillations can be reduced, thereby improving energy efficiency. Specifically, when the diameter of the randomly packed column exceeds 200 mm, it is preferable to use a plate column. Furthermore, it is more preferable that the diameter of the randomly packed column is 100 mm or less.

[0020] In the case of randomly packed columns, the hold-up volume is large. Also, in plate columns, the hold-up volume is large because a liquid layer exists on each plate. In contrast, structured packed columns generally have a small hold-up volume, which allows for shorter start-up operation times. The start-up operation time refers to the time it takes for a concentration distribution to form throughout the distillation column group, and the effect of the hold-up volume on the start-up operation time increases the closer the column is to the "product extraction column," which has a high concentration level relative to the natural abundance ratio. An example of structured packing that is widely used in air separation plants is "Melapack" manufactured by Sulzer ChemTech, and its HETP is about 150mm to 250mm for types with a large specific surface area. In a stable isotope enrichment system using distillation, the diameter of the tower decreases from the upstream tower that supplies the raw material to the downstream tower that extracts the product, and most of the energy required is consumed by the upstream distillation tower. Therefore, by adopting structured packed columns in towers close to the tower from which the product is extracted, the number of distillation columns increases, but the startup operation time can be significantly shortened, and at the same time, the decrease in energy efficiency can be reduced because the diameter of the additional distillation columns is small.

[0021] Therefore, in the stable isotope enrichment apparatus 100 of this embodiment, among the group of cascaded distillation columns, at least the column that supplies the raw material is a plate column, and the columns other than the plate column are packed with packing material.

[0022] The packed tower group can be configured in the following three ways depending on the design conditions of energy efficiency and start-up operation time. (1) All distillation columns are randomly packed columns. (2) It has one or more structured packed columns and one or more random packed columns, and one or more random packed columns are located on the secondary side of one or more structured packed columns. (3) It has one or more structured packed columns and one or more random packed columns, and one or more structured packed columns are located on the secondary side of one or more random packed columns.

[0023] The plate spacing of the plate column is preferably about 100 mm, and a plate spacing wider than the HETP of the random packing is not suitable.

[0024] Specifically, as described above, the first distillation column 1 to the j-1th distillation column j-1 are plate columns, and the jth distillation column j to the nth distillation column n are packed columns. That is, the stable isotope enrichment apparatus 100 of this embodiment has a plate column group (the first distillation column 1 to the j-1th distillation column j-1) consisting of one or more plate columns, and a packed column group (the jth distillation column j to the nth distillation column n) consisting of one or more packed columns. The packed tower group is located on the secondary side of the plate tower group, and the packed tower group may have one of the three configurations described above depending on the design conditions. The plate column group includes a first distillation column 1 for supplying a raw material, and the packed column group includes an nth distillation column n for extracting (discharging) a product.

[0025] The tower to which the raw material is supplied does not necessarily have to be the first distillation tower 1, and a distillation tower serving as a recovery section may be located in front of the tower to which the raw material is supplied. Also, the tower from which the product is extracted does not necessarily have to be the final tower (the nth distillation tower n), and may be located in the middle of the group of distillation towers.

[0026] In the stable isotope enrichment apparatus 100 of this embodiment, the randomly packed columns are connected in parallel, so that the equivalent column diameter can be increased while maintaining the HETP. In randomly packed columns connected in parallel, either a condenser or a reboiler should be installed for each column connected in parallel, and the other may be installed as a shared device. From the viewpoints of reducing equipment costs and enabling stable operation of the apparatus, the number of randomly packed columns connected in parallel is desirably 20 or less, and more preferably less than 10.

[0027] Each distillation tower (first distillation tower 1 to nth distillation tower n) is provided with one or more condensers 21. Condenser 21 is provided on a circulation line 32, both ends of which are connected to different positions at the top of each distillation tower. Condenser 21 has the function of liquefying the gas that has risen inside the distillation tower by heat exchange, and then allowing the gas to descend again inside the distillation tower.

[0028] Each distillation column is provided with at least one reboiler 22. The reboiler 22 is provided on a circulation line 33, both ends of which are connected to different positions in the bottom of each distillation column. The reboiler 22 has the function of vaporizing the liquid that has descended inside the distillation column through heat exchange, and then raising the liquid again inside the distillation column.

[0029] One end of the raw material feed line 30 is connected to the middle part of the first distillation column 1. The raw material feed line 30 is a path for supplying the stable isotope to the middle part of the first distillation column 1. The raw material supply line 30 is provided with a valve. The middle part of the distillation column refers to a position other than the top and bottom of the distillation column. The purity of the stable isotope supplied from the raw material supply line 30 is desirably high, at 99.999% or more.

[0030] A portion of the vapor from the bottom of each distillation column, except for the final column, in which the concentration of heavy stable isotopes has been increased, is supplied to the top of the next column via line 34 and valve 23. The driving force for the flow is the pressure difference between the bottom of a distillation column and the top of the next column. The vapor supplied to the top of the next column is liquefied in condenser 21 together with the rising vapor within that column, and is refluxed to the top of that column.

[0031] In addition, a portion of the reflux liquid near the top of each distillation column in which the concentration of light stable isotopes has been increased, except for the first distillation column 1, is supplied to the bottom of the preceding column via a line 35 and a valve 24. The driving force for the flow is the liquid head pressure of the reflux liquid. The reflux liquid supplied to the bottom of the preceding column is vaporized in a reboiler 22 together with the reflux liquid in that column, and is refluxed to the bottom of that column.

[0032] The product line 31 is a path for extracting the enriched stable isotope component as a product from the nth distillation column n. One end of the product line 31 is connected to a portion of the nth distillation column n near the column bottom. The product is a stable isotope component enriched to a high concentration (e.g., 99% or more).

[0033] As described above, the stable isotope enrichment apparatus 100 of this embodiment has a plate tower group consisting of one or more plate towers and a packed tower group consisting of one or more packed towers, with the packed tower group being located on the secondary side of the plate tower group. This makes the stable isotope enrichment apparatus 100 of this embodiment highly energy efficient and reduces equipment costs. Furthermore, the stable isotope enrichment apparatus 100 of this embodiment has an excellent balance between energy efficiency and startup operation time.

[0034] In addition, in the stable isotope enrichment apparatus 100 of this embodiment, the column diameter of the randomly packed column is 200 mm or less, and a plate column is used when the column diameter of the randomly packed column exceeds 200 mm. As a result, the height of the distillation column can be reduced, further improving energy efficiency.

[0035] In the present invention, when the diameter of the randomly packed column is about 100 to 200 mm, a plate column or a structured packed column may be used instead of the randomly packed column. When a plate column is used, the height of the distillation column can be reduced as in the stable isotope enrichment apparatus 100 of the present embodiment, and therefore the energy efficiency is improved. On the other hand, a plate column has a larger hold-up volume than a randomly packed column in which the particle size of the random packing is large (the specific surface area of ​​the packing is small). In this case, the start-up operation time is extended.

[0036] When the diameter of a random packed column is about 200 mm, the HETP is about the same as that of a structured packed column with a large specific surface area. When a structured packed column is used, the energy efficiency is about the same, but the start-up operation time can be shortened. In addition, if the diameter of the randomly packed column is less than 100 mm, a structured packed column may be used if it is a column adjacent to the column that extracts the product, including the column that extracts the product. The column adjacent to the column that extracts the product has a small diameter, and the energy required for operation accounts for a small proportion of the total energy. Therefore, the decrease in energy efficiency is small, and the start-up operation time can be significantly shortened.

[0037] Furthermore, in the stable isotope enrichment apparatus 100 of this embodiment, the number of randomly packed columns connected in parallel is 20 or less, so that the equipment costs can be further reduced.

[0038] Although the stable isotope enrichment device of the present invention has been described above with reference to the embodiments, the present invention is not limited to these embodiments. Each configuration and their combination in the above-described embodiments are merely examples, and addition, omission, substitution, and other modifications of the configuration are possible without departing from the spirit of the present invention. EXAMPLES

[0039] The present invention will be described in detail below with reference to examples, but the present invention is not limited to these.

[0040] Example 1 In the first embodiment, a stable isotope enrichment device 200 shown in FIG. 18 O was concentrated. The stable isotope enrichment 200 has a basic configuration similar to that of the stable isotope enrichment 100. The distillation column group is composed of 12 distillation columns, the first distillation column 1 being a plate column, and the second distillation column 2 to the twelfth distillation column 12 being randomly packed columns. Liquefied nitrogen was used as the cold source for the condenser 21, and the liquefied nitrogen was supplied to each condenser 21 through the liquefied nitrogen supply line 38. Gaseous nitrogen was used as the heat source for the reboiler 22, and the gaseous nitrogen was supplied to each reboiler 22 through the gaseous nitrogen supply line 39. The stable isotope enrichment apparatus 200 was also provided with an isotope scrambler 20. One end of the isotope enriched gas extraction line 36 was connected to the middle part of the ninth distillation column 9, and the other end was connected to the isotope scrambler 20, so that a part or all of the oxygen was extracted and supplied to the isotope scrambler 20. The oxygen that underwent the isotope exchange reaction in the isotope scrambler 20 was returned to the intermediate portion of the ninth distillation column 9 via the isotope-enriched gas return line 37 .

[0041] The composition of the high purity oxygen feedstock to be supplied was as shown in Table 1. The tray spacing of the first distillation column 1 was 100 mm. In the second distillation column 2 to the sixth distillation column 6, the column diameter per distillation column was in the range of 100 to 200 mm. In the seventh distillation column 7 to the twelfth distillation column 12, the column diameter of each distillation column was 100 mm or less. Randomly packed columns were connected in parallel in the second distillation column 2 to the eighth distillation column 8. In each of the second distillation column 2 to the eighth distillation column 8, condensers were provided for the same number of distillation columns connected in parallel, and each column was provided with one reboiler as a shared device. The number of distillation columns connected in parallel was 20 or less in each case.

[0042] [Table 1]

[0043] When the apparatus was in a stable state, the abundance ratio of stable isotope molecules in the oxygen gas discharged from the bottom of the twelfth distillation column 12 was as shown in Table 2. The total heat exchange capacity of the condenser and reboiler was 815 kW. The start-up operation time of the equipment was about 270 days.

[0044] [Table 2]

[0045] Comparative Example 1 In Comparative Example 1, the stable isotope enrichment device 300 shown in FIG. 18 O was concentrated. The stable isotope enrichment apparatus 300 has 13 distillation columns, and is almost the same as the stable isotope enrichment apparatus 200, except that the first distillation column 1 is a packed column packed with random packing. The isotope scrambler 20 is connected to the middle part of the tenth distillation column 10.

[0046] The composition of the high purity oxygen feedstock to be supplied was as shown in Table 1. In the first distillation column 1, the column diameter of each distillation column was 200 mm or more. In the second distillation column 2 to the thirteenth distillation column 13, the column diameter of each of the distillation columns was 200 mm or less. In the first distillation column 1 to the ninth distillation column 9, randomly packed columns were connected in parallel. In each of the first distillation column 1 to the ninth distillation column 9, condensers were provided for the same number of distillation columns connected in parallel, and each column had one reboiler as a shared device. The number of distillation columns connected in parallel was 20 or less in each case.

[0047] When the apparatus was in a stable state, the abundance ratio of stable isotope molecules in the oxygen gas discharged from the bottom of the thirteenth distillation column 13 was as shown in Table 3. The total heat exchange capacity of the condenser and reboiler was 1570 kW. The start-up operation time of the equipment was about 270 days.

[0048] [Table 3]

[0049] From the above results, in Example 1, the amount of heat exchange required could be reduced by about 50% compared to Comparative Example 1, and the number of distillation columns required could be reduced by one. Furthermore, in Example 1, the first distillation column 1 could have only one condenser. Therefore, it was found that the stable isotope enrichment device of the present invention has high energy efficiency and can reduce equipment costs.

[0050] In addition, in Example 1, some of the second distillation column 2 to the sixth distillation column 6 may be structured packed columns. In that case, the total heat exchange amount will be about the same as in Example 1, and the number of condensers in the second distillation column 2 to the sixth distillation column 6 can be reduced to only one. In addition, since the hold-up amount is reduced, the start-up operation time is expected to be shortened.

[0051] Example 2 In the second embodiment, a stable isotope enrichment device 400 shown in FIG. 18 O was concentrated. The stable isotope enrichment apparatus 400 has 10 distillation columns, with the first distillation column 1 to the third distillation column 3 being plate columns and the fourth distillation column 4 to the tenth distillation column 10 being randomly packed columns. The stable isotope enrichment apparatus 400 is almost the same as the stable isotope enrichment apparatus 200, except for the total number of distillation columns, the number of plate columns, and the number of packed columns. The isotope scrambler 20 was connected to the middle of the seventh distillation column 7.

[0052] The composition of the high purity oxygen feedstock to be supplied was as shown in Table 1. The plate spacing between the first distillation column 1 to the third distillation column 3 was 100 mm. In the fourth distillation column 4 to the tenth distillation column 10, the column diameter of each distillation column was 100 mm or less. Random packing was connected in parallel in the fourth distillation column 4 to the sixth distillation column 6. In each of the fourth distillation column 4 to the sixth distillation column 6, condensers were provided in the same number as the distillation columns connected in parallel, and each column had one reboiler as a shared device. The number of distillation columns connected in parallel was 10 or less in each case.

[0053] When the apparatus was in a stable state, the abundance ratio of stable isotope molecules in the oxygen gas discharged from the bottom of the tenth distillation column 10 was as shown in Table 4. The total heat exchange capacity of the condenser and reboiler was 640 kW.

[0054] [Table 4]

[0055] From the above results, it was found that increasing the number of tray towers further improves energy efficiency, and also reduces the number of distillation towers and condensers, thereby reducing equipment costs. On the other hand, in Example 2, when the fourth distillation column 4 is changed from a randomly packed column to a plate column, the length of the required distillation column becomes longer, and the number of distillation columns needs to be increased, which eliminates the advantage of changing from a randomly packed column to a plate column.

[0056] Example 3 In the third embodiment, a stable isotope enrichment device 500 shown in FIG. 18 O was concentrated. The stable isotope enrichment apparatus 500 has 13 distillation columns, with the first distillation column 1 being a plate column, the second distillation column 2 to the eleventh distillation column 11 being randomly packed columns, and the twelfth distillation column 12 to the thirteenth distillation column 13 being structured packed columns. The stable isotope enrichment apparatus 500 is almost the same as the stable isotope enrichment apparatus 200, except that the total number of distillation columns, the number of plate columns, and the number of packed columns are different. The isotope scrambler 20 was connected to the middle of the ninth distillation column 9.

[0057] The composition of the high purity oxygen feedstock to be supplied was as shown in Table 1. The tray spacing of the first distillation column 1 was 100 mm. In the second distillation column 2 to the eleventh distillation column 11, the column diameter of each of the distillation columns was 200 mm or less. In the twelfth distillation column 12 to the thirteenth distillation column 13, the HETP of the distillation column was 200 mm. Random packing was connected in parallel in the second distillation column 2 to the eighth distillation column 8. In each of the second distillation column 2 to the eighth distillation column 8, condensers were provided in the same number as the distillation columns connected in parallel, and each column had one reboiler as a shared device. The number of distillation columns connected in parallel was 20 or less in each case.

[0058] When the apparatus was in a stable state, the abundance ratio of stable isotope molecules in the oxygen gas discharged from the bottom of the thirteenth distillation column 13 was as shown in Table 5. The total heat exchange capacity of the condenser and reboiler was 817 kW. The start-up operation time of the equipment was about 250 days.

[0059] [Table 5]

[0060] From the above results, in Example 3, by using a structured packed tower near the tower where the product is extracted, the start-up operation time could be reduced by about 20 days compared to Example 1 with almost the same amount of heat exchange. Therefore, it was found that the stable isotope enrichment apparatus of the present invention can be configured to have an excellent balance between energy efficiency and startup operation time.

[0061] The above results can be applied not only to oxygen but also to other stable isotopes. For example, the present invention can be applied to the enrichment of stable isotopes of carbon, hydrogen, and nitrogen, making it possible to provide an apparatus with high energy efficiency and reduced equipment costs. [Industrial Applicability]

[0062] The present invention is a distillation apparatus including a distillation column group in which a plurality of distillation columns are cascaded, and is applicable to a stable isotope enrichment apparatus that enriches stable isotope atoms that exist in extremely small amounts in nature. [Explanation of symbols]

[0063] 1, 3, 7, 8, 9, 10, 11, 12, 13, j-1, j, n...Distillation column 20. Isotope Scrambler 21 Capacitor 22 Reboiler 23, 24 Valves 30 Raw material feed line 31 Product Line 32, 33...Circulation line 36 Isotope-enriched gas extraction line 37. Isotope-enriched gas return line 38 Liquefied nitrogen supply line 39 Nitrogen gas supply line 100, 200, 300, 400, 500...Stable isotope concentrator

Claims

1. A stable isotope enrichment apparatus for enriching a stable isotope by distillation, comprising: A distillation column group in which a plurality of distillation columns are cascaded, The distillation column group includes: A plate tower group consisting of one or more plate towers; A packed tower group consisting of one or more packed towers, the packed tower group including at least one random packed tower, A stable isotope enrichment apparatus, wherein the group of packed towers is located on the secondary side of the group of plate towers.

2. 2. The stable isotope enrichment apparatus according to claim 1, wherein all of the packed towers in the group of packed towers are randomly packed towers.

3. The group of packed columns includes one or more structured packed columns and one or more random packed columns, 2. The stable isotope enrichment apparatus according to claim 1, wherein one or more randomly packed columns are located on the secondary side of one or more structured packed columns.

4. The group of packed columns includes one or more structured packed columns and one or more random packed columns, 2. The stable isotope enrichment apparatus according to claim 1, wherein one or more structured packed columns are located on the secondary side of the one or more random packed columns.

5. Among the distillation columns, 5. The stable isotope enrichment apparatus according to claim 1, wherein the distillation column to which the raw material is supplied is a plate column.

6. The randomly packed column comprises:

6. The stable isotope enrichment apparatus according to claim 2, wherein the number of the randomly packed columns connected in parallel is 20 or less.

7. 7. The stable isotope enrichment apparatus according to claim 2, wherein the randomly packed column has a column diameter of 200 mm or less.

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