JP2022073512A - Stable isotope concentrator, and stable isotope concentration method - Google Patents

Abstract

To provide a stable isotope concentrator of which a starting time can be shortened by a simple configuration, and a stable isotope concentration method.SOLUTION: A stable isotope concentrator 100 comprises: a distillation tower group in which a plurality of distillation towers are cascade-connected; a raw material introduction path 30 which introduces a stable isotope having a purity of a natural abundance ratio or higher to one distillation tower of the distillation tower group as a raw material; and a product derivation path 31 which derives a concentrated stable isotope from other distillation towers as a product. At least one or more distillation towers of the distillation tower group have one or more introduction ports 40 that introduce a stable isotope having a purity higher than that of the raw material into the distillation tower.SELECTED DRAWING: Figure 1

Description

The present invention relates to a stable isotope concentrator and a method for concentrating stable isotopes.

Stable isotopes are used in the fields of organic chemistry and biochemistry to obtain information on various reactions, structures and functions of organic and biological substances. Specifically, as a tracer, it is applied to NMR analysis, application to drug discovery / organic synthesis using kinetic isotope effect that changes the reaction rate by isotope substitution, and red using the difference in spectroscopic properties. Applications to external and Raman spectroscopy can be mentioned.

For example, hydrogen has ^two types of stable isotopes, 1H and ^2H (hereinafter referred to as "deuterium" or "D"). Deuterium (D2O), which is a substance in which deuterium and oxygen _are combined, is a typical NMR deuterated solvent, and deuterated drugs have the effect of suppressing the metabolism of drugs in the body and have medicinal properties. It has been reported that the time is prolonged and the side effects due to the toxicity of metabolites are reduced. ^In addition, oxygen has three types of stable isotopes, ¹⁶ O, ¹⁷ O, and ¹⁸ O, and H ₂₁₈ O is used as a raw material for PET examination, which is a diagnostic method for cancer.

As a method for concentrating a stable isotope, there are various methods such as an electrolysis method, a laser separation method, a chemical exchange method, and a distillation method. For example, methods for industrially concentrating heavy water include a chemical exchange method, a water electrolysis method, a water-hydrogen isotope exchange method, and a distillation method. The former three methods have the advantage of having a large separation coefficient. On the other hand, as a demerit, in the case of the chemical exchange method, hydrogen sulfide or the like is used as the fluid, so that it is difficult to handle. Moreover, in the water electrolysis method and the water-hydrogen isotope exchange method, it is necessary to electrolyze water, which requires a very large amount of electric power.

The distillation method is easy to handle and is superior to the electrolysis method in that it requires less energy. However, since the vapor pressure ratio of H ₂ O and D ₂ O is very small, when trying to concentrate to a high concentration from the natural abundance ratio, the number of theoretical plates required is large and the length of the distillation column becomes long, and the apparatus becomes It tends to be very large. In addition, since the natural abundance ratio is very small, it is necessary to treat a large amount of raw water, which increases the energy cost per product.

By the way, stable isotopes used as products in tracers and organic synthesis / drug discovery are often required to have a high concentration of 99% or more. In addition, the stable isotopes used as products have a reduced enrichment to a concentration of less than 99%. Stable isotopes with a lower enrichment than the stable isotopes used as products (hereinafter, also simply referred to as "deteriorated stable isotopes") will not be used again for tracers and organic synthesis / drug discovery, and will be waste liquid. Alternatively, it will be discarded as waste gas.

However, although the concentration of the degraded stable isotope is lower than that of the product, it contains a very high concentration of stable isotope compared to the natural abundance, and if it can be concentrated again, it will be re-traced and reacted. Can be used. Products that have been re-concentrated using degraded stable isotopes as raw materials need to be supplied at a lower cost than unused products, so it is important how low the cost can be concentrated. That is, in a stable isotope concentrating device using a deteriorated stable isotope as a raw material, it is required that the device cost is low, the operation cost is low, the device configuration and the handling of the device are simple, and the operation management cost is low.

For example, Patent Document 1 discloses a concentrator based on a water-hydrogen isotope exchange method, and describes a method of reducing power consumption and reducing operating costs by using a solid polymer fuel cell. There is.

Japanese Unexamined Patent Publication No. 2001-286737

In the case of the water-hydrogen isotope exchange method described in Patent Document 1, it is necessary to use expensive platinum or the like as a catalyst for the isotope exchange tower. Further, since there is an electrolytic unit and an isotope exchange unit and the device configuration is complicated, there is a problem that the device cost is high. In addition, the fuel cell used to reduce power consumption is an expensive device and is not suitable as a device for reconcentration.

By the way, in the case of the distillation method, there is a problem that the apparatus becomes large in order to concentrate the stable isotope from the natural abundance to a high concentration, but in the case of reconcentrating the deteriorated stable isotope, the stable isotope concentration of the raw material is high. Since the number of theoretical plates required is reduced, the device can be miniaturized. Further, since the distillation method is easy to handle, it is suitable for reconcentration using a deteriorated stable isotope as a raw material.

On the other hand, the distillation method requires gas-liquid contact inside the device, and the device needs to contain a large amount of liquid. In addition, since the vapor pressure ratio between isotopes is very small, the separation coefficient is small and the distillation column is long. Therefore, there is a feature that the time from the activation of the apparatus to the formation of the concentration distribution in the entire distillation column (hereinafter referred to as "startup time") is long.

For example, when concentrating ¹⁸ O, which is a stable isotope of oxygen, to 99% or more from the natural abundance ratio, a start-up time of 6 months to 1 year or more is required, and reconcentration is also several weeks to several months depending on the equipment configuration. Requires. In addition, since the concentrated product cannot be collected during startup, the manufacturing cost of the product increases as the startup time becomes longer.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a stable isotope concentrator capable of shortening the start-up time and a method for concentrating stable isotopes by a simple configuration.

In order to achieve the above problems, the present invention adopts the following configuration.
[1] A stable isotope concentrator that concentrates stable isotopes by distillation.
A group of distillation columns in which multiple distillation columns are connected in cascade,
A raw material introduction route for introducing a stable isotope having a purity higher than the natural abundance ratio as a raw material into one of the distillation columns.
The distillation column group includes a product derivation route for deriving a stable isotope concentrated as a product from another distillation column.
A stable isotope concentrator in which at least one of the distillation columns has one or more introduction routes for introducing a stable isotope having a purity higher than that of the raw material inside the distillation column.
[2] A stable isotope concentrator that concentrates stable isotopes by distillation.
Distillation tower and
A raw material introduction route for introducing a stable isotope having a purity higher than the natural abundance ratio as a raw material into the distillation column.
A product derivation route for deriving a stable isotope concentrated as a product from the distillation column is provided.
A stable isotope concentrator in which the distillation column has one or more introduction routes for introducing a stable isotope having a higher purity than the raw material inside the distillation column.
[3] A method for concentrating stable isotopes by distilling using a plurality of cascade-connected distillation columns.
Among the plurality of distillation columns, a stable isotope having a purity equal to or higher than the natural existence ratio is introduced into one of the distillation columns as a raw material, and a stable isotope having a purity higher than that of the raw material is introduced into at least one of the distillation columns. After introducing the body inside the distillation column and activating multiple of the distillation columns,
A method for concentrating stable isotopes, which derives a stable isotope enriched from the other distillation columns as a product among the plurality of distillation columns.
[4] A method for concentrating stable isotopes by distilling using a distillation column.
A stable isotope having a purity higher than the natural existence ratio is introduced into the distillation column as a raw material, and a stable isotope having a purity higher than that of the raw material is introduced into the distillation column inside the distillation column to carry out the distillation. After activating the tower
A method for concentrating stable isotopes, which derives stable isotopes enriched from the distillation column as a product.

The stable isotope enricher and the stable isotope enrichment method of the present invention have a simple configuration and can shorten the start-up time.

It is a system diagram which shows the main part of the stable isotope enrichment apparatus which concerns on embodiment of this invention. It is a system diagram which shows the main part of the heavy water reconcentrator used in an Example and a comparative example.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings, showing embodiments.
In addition, in the drawings used in the following explanation, in order to make the features easy to understand, the featured parts may be enlarged for convenience, and the dimensional ratios of each component may not be the same as the actual ones. not.
Further, in the present specification, "deterioration" means that the enrichment is lower than that of the stable isotope used as a product, and "deterioration stable isotope" is a stable isotope used as a product. It means a stable isotope with a lower enrichment than.

<Stable isotope concentrator>
FIG. 1 is a system diagram showing a main part of a stable isotope concentrator according to an embodiment of the present invention.
The stable isotope concentrator 100 of the present embodiment includes a group of distillation columns in which a plurality of distillation columns are cascaded, a plurality of capacitors 20, a plurality of reboilers 21, a raw material feed line (raw material introduction path) 30, and a product. It includes a line (product derivation route) 31 and a plurality of introduction routes 40.

The stable isotope concentrator 100 of the present embodiment is a device for concentrating stable isotopes of hydrogen, carbon, oxygen and nitrogen by distillation.
The stable isotope concentrator 100 of the present embodiment is preferably used for reconcentration of stable isotopes whose concentration has decreased after being used as a product. Further, the stable isotope concentrator 100 of the present embodiment is naturally applicable to enrichment from the natural abundance ratio.
The stable isotope is not particularly limited, and examples thereof include heavy water (D ₂ O), H ₂ ¹⁸ O, ¹⁸ O ₂ , ¹³ CO, and ¹⁵ N ₂ .

Hereinafter, the nth distillation column from the upstream end of the distillation column group is referred to as the nth distillation column.
The first distillation column 1 to the nth distillation column n are cascaded in the order of the column numbers.
The first distillation column 1 to the nth distillation column n concentrates a stable isotope having a low boiling point on the top side of the column by distilling a heated or cooled stable isotope, and a high boiling point on the bottom side of the column. It is designed to concentrate stable isotopes.
When a plurality of distillation columns are connected in cascade, n is a number of 2 or more.
On the other hand, when a stable isotope close to the purity of the product is used as a raw material and the concentration can be concentrated to the product concentration in one distillation column, n can be 1 (that is, one distillation column). .. In this case, the tower for supplying the raw material and the tower for collecting the product are the same.

The diameter of the first distillation column 1 to which the raw material is supplied is the largest, and gradually decreases toward the end. Each distillation column may be a packed column filled with a regular packed bed, a packed column filled with an irregular packed bed, or a shelf column.

One capacitor 20 is provided for each distillation column (first distillation column 1 to nth distillation column n). The condenser 20 is provided in a circulation line 32 in which both ends are connected at different positions on the top of each distillation column. The condenser 20 has a function of liquefying the gas that has risen in the distillation column by heat exchange and lowering the inside of the distillation column again.
In addition, one capacitor 20 may be provided for each distillation column (first distillation column 1 to nth distillation column n) every few columns.

One reboiler 21 is provided for each distillation column. The reboiler 21 is provided on a circulation line 33 in which both ends are connected at different positions on the bottom of each distillation column. The reboiler 21 has a function of vaporizing the liquid that has descended in the distillation column by heat exchange and raising the inside of the distillation column again.
It should be noted that the reboiler 21 may be provided once every several columns for each distillation column (first distillation column 1 to nth distillation column n).

One end of the raw material feed line 30 is connected to the intermediate portion of the first distillation column 1. The raw material feed line 30 is a route for introducing a stable isotope as a raw material into the intermediate portion of the first distillation column 1.
Here, the intermediate portion of the distillation column indicates a position other than the top and bottom of the distillation column.
The position (height) at which the raw material is introduced into the first distillation column 1 is not limited to the intermediate portion, and may be close to the stable isotope concentration of the raw material in the steady state of the first distillation column 1. preferable.
Further, the raw material supply line 30 may be provided with a valve.

As the stable isotope as a raw material, a stable isotope having a concentration equal to or higher than the natural abundance can be used, and it is preferable to use a deteriorated stable isotope.
The concentration of the degraded stable isotope is not particularly limited as long as it is equal to or higher than the natural abundance ratio, and a concentration of less than 99% may be used.

Except for the final column, a part of the steam at the bottom of each distillation column having an increased concentration of the high boiling point component of the stable isotope is supplied to the top of the next column via the path 34. The driving force of the flow is the pressure difference between the bottom of one distillation column and the top of the next column. The steam supplied to the top of the next tower is liquefied by the condenser 20 together with the rising steam in the tower, and is returned to the top of the tower.

Further, except for the first distillation column 1, a part of the reflux liquid near the top of each distillation column in which the concentration of the low boiling point component of the stable isotope was increased is passed through the path 35 to the column of the front column. Supplied to the bottom. The driving force of the flow is the head pressure of the reflux liquid.
A compressor may be used as the driving force of the flow. When a compressor is used, the gas at the top of the tower can be compressed and supplied to the front tower.
The reflux liquid supplied to the bottom of the front tower is vaporized by the reboiler 21 together with the reflux liquid in the tower, and is returned to the bottom of the tower.

The product line 31 is a route for deriving the concentrated 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 bottom of the column. The product is a stable isotope component concentrated to a high concentration (eg, 99.9% or higher).

The tower for supplying the raw material does not necessarily have to be the first distillation column 1, and a distillation column serving as a recovery unit may be located in front of the tower for supplying the raw material. Further, the column for collecting products does not necessarily have to be the final column (nth distillation column n), and may be in the middle of the distillation column group.

The introduction path 40 is provided in each path that joins the circulation line 33 located at the bottom of each distillation column. A valve (on-off valve) is provided in each of the introduction paths 40.
The introduction route 40 is an introduction port for introducing a stable isotope having a purity higher than that of the raw material (hereinafter, simply referred to as “high-concentration stable isotope”) inside each distillation column. By opening the valve installed in the introduction path 40, a high concentration stable isotope can be introduced into the inside of each distillation column from the supply source (not shown) via the circulation line 33.

The high-concentration stable isotope is not particularly limited. For example, when a degraded stable isotope having a concentration of about 99% is used as a raw material, a product concentrated to a high concentration (for example, 99.9% or more) may be used. As will be described later, the introduced high-concentration stable isotope is finally collected as a product, so that the raw material cost does not increase.

In the stable isotope concentrator 100 of the present embodiment, the configuration in which the introduction path 40 is provided in the circulation line 33 located at the bottom of each distillation column is described as an example, but the present invention is not limited to this.
For example, the introduction path 41 that joins the circulation line 32 may be provided, or the introduction path 42 connected to each distillation column may be provided with a valve. Further, the configuration may have any one of the introduction routes 40, 41, 42, or may have two or more.
Further, the introduction path 40 may be provided in one or more in each distillation column, or may be provided in every several columns.

For high-concentration stable isotopes, it is preferable to introduce stable isotopes with a concentration close to the stable isotope enrichment at the bottom of each column in the steady state.
For example, if there is a recovery unit in front of the tower that supplies the raw material, it is not suitable to supply the recovery unit with a stable isotope having a higher concentration than the deteriorated stable isotope.

<Stable isotope enrichment method>
Next, a method for concentrating stable isotopes of the present embodiment (hereinafter, simply referred to as “concentration method”) will be described. The enrichment method of the present embodiment is the operation method of the stable isotope enricher 100 described above, and is particularly characterized when the apparatus of the stable isotope enricher 100 is started.

In the enrichment method of the present embodiment, a stable isotope having a purity equal to or higher than the natural abundance ratio is introduced into one of the plurality of distillation towers as a raw material, and a high concentration stable isotope is introduced into at least one distillation column. After introducing the body into the inside of the distillation tower and starting the stable isotope concentrating device 100, the stable isotope concentrated from the other distillation towers among the plurality of distillation towers is derived as a product.

Specifically, first, a high-concentration stable isotope is introduced into the distillation column in a gas or liquid state from the introduction path 40 of each distillation column.
For example, when introducing by gas from the introduction path 40, a cold heat source is supplied to the condenser 20, the stable isotope is cooled and liquefied, and the liquid is stored in the bottom of each distillation column.
Next, after the amount of liquid required for the operation of the reboiler 21 is accumulated in the bottom of each distillation column, a heating source is supplied to the reboiler 21.
After confirming that each distillation column is stable, the introduction of the raw material (deteriorated stable isotope) into the first distillation column 1 is started by the raw material feed line 30. The enrichment operation of the stable isotope enricher 100 is started. That is, after the start of the stable isotope concentrator 100 is completed, the product is derived from the nth distillation column n by the product line 31.

By the way, in general, in a distillation separation device for a stable isotope having a low molecular weight, at the time of activation, a low-concentration raw material is stored in each column, and then the distillation column is activated to supply the raw material while supplying the concentration of the product take-out unit. You have to wait until it rises. The time required from the start of the concentration operation until the product can be collected is the same as the start-up time, which is the time until the product is concentrated in the product part at the bottom of the distillation column and the concentration distribution is created in the distillation column.

On the other hand, according to the stable isotope concentrating device 100 and the method for concentrating stable isotopes of the present embodiment, a stable isotope having a purity (concentration) higher than that of the natural abundance is used as a raw material and at the time of starting the device. In order to reduce the time required for concentrated stable isotopes to accumulate at the bottom of the distillation column by introducing high-concentration stable isotopes into at least one distillation column (part or preferably all of the distillation column). , The start-up time can be shortened by a simple device configuration and a simple method. Therefore, according to the stable isotope enrichment apparatus 100 and the stable isotope enrichment method of the present embodiment, the apparatus cost and the manufacturing cost can be reduced.

Further, according to the stable isotope concentrator 100 and the method for concentrating stable isotopes of the present embodiment, stable isotopes whose concentration is slightly lower than that of the product after using the product (high concentration stable isotope). It is particularly useful when (that is, a degraded stable isotope) is used as a raw material and a small amount of product is used as a high concentration stable isotope when reconcentrating the raw material. That is, it is most suitable as a concentrator and a concentrating method when reconcentrating a deteriorated stable isotope which has been conventionally discarded as a raw material. Since the product (high-concentration stable isotope) introduced at the start of the device is finally collected as a product, the raw material cost does not increase.

Although the stable isotope concentrator of the present invention has been described above with reference to embodiments, the present invention is not limited to these embodiments. Each configuration in the above embodiment and a combination thereof are examples, and the configuration can be added, omitted, replaced, and other changes are possible without departing from the spirit of the present invention.

In the stable isotope concentrator 100 of the above-described embodiment, various changes can be made according to the physical properties of the substance to be distilled and the configuration of the apparatus. For example, the flow directions of the path 34 and the path 35 may be opposite. Further, the connection position of the route 34 and the route 35 is not limited to the configuration in which the "front tower is the bottom of the tower" and the "next tower is the top of the tower".

Hereinafter, the present invention will be described in detail by way of examples, but the present invention is not limited thereto.

(Example 1)
In Example 1, heavy water reconcentration device (stable isotope concentrator) 200 shown in FIG. 2 was used to reconcentrate heavy water (deteriorated heavy water) having a concentration lower than that of the product.

The basic configuration of the heavy water reconcentrator 200 is the same as that of the stable isotope reconcentrator 100, that is, two series-connected first distillation column 1 and second distillation column 2 and one pump. 20, two revoirers 21, a raw material feed pump 22, a liquid feed pump 23, a cooling water circulation device 24, a raw material feed line 30, a product line 31, a cooling water circulation line 36, and a circulation line 33. The introduction route 40 is provided.

The first distillation column 1 and the second distillation column 2 are both packed columns filled with a regular packed material.
In the heavy water reconcentrator 200, the cooling water is a cooling heat source to the condenser 20, and the cooling water is supplied from the cooling water circulation device 24 via the cooling water circulation line 36. The heating source of the reboiler 21 is an electric heater.
The liquid at the bottom of the first distillation column 1 having an increased heavy water concentration is supplied to the top of the second distillation column 2 via the liquid feed pump 23 by the path 35.
The steam at the top of the second distillation column 2 having a low heavy water concentration is supplied to the bottom of the first distillation column 1 via the path 34. The driving force of the flow is the pressure difference between the bottom of the first distillation column 1 and the top of the second distillation column 2. The steam supplied to the bottom of the first distillation column 1 is liquefied by the condenser 20 together with the rising steam in the column and is refluxed into the column.

At the time of starting the heavy water reconcentrator 200, first, the heavy water having the composition shown in Table 2 is introduced into the reboiler 21 located at the bottom of the first distillation column 1 and the introduction path 40 is located at the bottom of the first distillation column 1. The liquid necessary for starting the reboiler 21 is stored in the reboiler 21 located at the bottom of the second distillation column 2, and the heavy water having the composition shown in Table 3 is located at the bottom of the second distillation column 2. The liquid required for starting the revoira 21 was stored by supplying it from the introduction route 40.
The heavy water having the composition shown in Table 2 was adjusted by mixing pure water with the heavy water having the composition shown in Table 3.

After confirming that the required amount of liquid has accumulated in the bottoms of the first distillation column 1 and the second distillation column 2, the reboiler 21 is started, and the deteriorated heavy water having the composition shown in Table 1 is added to the raw material feed line. From No. 30, the raw material was supplied to the intermediate portion of the first distillation column 1, and the concentration operation of the heavy water reconcentrator 200 was started.
At the same time as the start of the concentration operation, the extraction of heavy water having a reduced deuterium concentration was started from the top of the first distillation column 1.
It took about 12 days from the start of the heavy water reconcentrator 200 to the deuterium concentration in the heavy water at the bottom of the second distillation column 2 reaching 99.9% or more. The abundance ratio of stable isotope molecules in the reconcentrated heavy water (product) delivered from the second distillation column 2 when the apparatus was stable was as shown in Table 4 below.

(Comparative Example 1)
In Comparative Example 1, the heavy water reconcentrator 200 shown in FIG. 2 was used to reconcentrate the deteriorated heavy water.
The composition of the raw material deteriorated heavy water supplied from the raw material feed line 30 is as shown in Table 1.
At the time of starting the apparatus, the deteriorated heavy water having the composition shown in Table 1 is introduced into the riboira 21 at the bottom of the first distillation column 1 and the riboira 21 at the bottom of the second distillation column 2 to start the riboira. The necessary liquid was stored.
In the same manner as in Example 1, the reboiler 21 is started, and the deteriorated heavy water having the composition shown in Table 1 is supplied from the raw material feed line 30 to the intermediate portion of the first distillation column 1 as a raw material, and at the same time as the start of the concentration operation, the first Extraction of heavy water having a reduced deuterium concentration was started from the top of the distillation column 1 of 1.
It took about 22 days from the start of the heavy water reconcentrator 200 to the deuterium concentration in the heavy water at the bottom of the second distillation column 2 reaching 99.9% or more. The abundance ratio of stable isotope molecules in the reconcentrated heavy water (product) delivered from the second distillation column 2 at the time of stabilization of the apparatus is as shown in Table 5 below.

In Example 1, the start-up time of Comparative Example 1 is reduced to about half of the start-up time of Comparative Example 1 by the concentration method including the stable isotope concentrator of the present invention and the start-up method of the concentrator, without incurring the device cost due to the simple device configuration. This made it possible to reduce the manufacturing cost when reconcentrating heavy water.
It was also confirmed that the high-concentration heavy water introduced when starting the enrichment device can be collected as a product, so that the start-up time can be shortened without increasing the raw material cost.

The present invention is an isotope concentrator provided with one or more distillation columns, a stable isotope concentrator that reconcentrates stable isotopes (deteriorated stable isotopes) whose concentration is lower than that of the product, and a method for activating the isotope concentrator. Applicable to.

1, 2, j, n ... Distillation column 20 ... Condenser 21 ... Ribola 30 ... Raw material feed line (raw material introduction route)
31 ... Product line (product out-licensing route)
32, 33 ... Circulation line 34, 35 ... Path 40, 41, 42 ... Introduction route 100, 200 ... Stable isotope concentrator

Claims (4)

A stable isotope concentrator that concentrates stable isotopes by distillation.
A group of distillation columns in which multiple distillation columns are connected in cascade,
A raw material introduction route for introducing a stable isotope having a purity higher than the natural abundance ratio as a raw material into one of the distillation columns.
The distillation column group includes a product derivation route for deriving a stable isotope concentrated as a product from another distillation column.
A stable isotope concentrator in which at least one of the distillation columns has one or more introduction routes for introducing a stable isotope having a purity higher than that of the raw material inside the distillation column. A stable isotope concentrator that concentrates stable isotopes by distillation.
Distillation tower and
A raw material introduction route for introducing a stable isotope having a purity higher than the natural abundance ratio as a raw material into the distillation column.
A product derivation route for deriving a stable isotope concentrated as a product from the distillation column is provided.
A stable isotope concentrator in which the distillation column has one or more introduction routes for introducing a stable isotope having a higher purity than the raw material inside the distillation column. It is a method for concentrating stable isotopes that concentrates stable isotopes by distillation using multiple distillation columns connected in cascade.
Among the plurality of distillation columns, a stable isotope having a purity equal to or higher than the natural existence ratio is introduced into one of the distillation columns as a raw material, and a stable isotope having a purity higher than that of the raw material is introduced into at least one of the distillation columns. After introducing the body inside the distillation column and activating multiple of the distillation columns,
A method for concentrating stable isotopes, which derives a stable isotope enriched from the other distillation columns as a product among the plurality of distillation columns. It is a method for concentrating stable isotopes by distilling using a distillation column.
A stable isotope having a purity higher than the natural existence ratio is introduced into the distillation column as a raw material, and a stable isotope having a purity higher than that of the raw material is introduced into the distillation column inside the distillation column to carry out the distillation. After activating the tower
A method for concentrating stable isotopes, which derives stable isotopes enriched from the distillation column as a product.

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