JP6865798B2 - How to operate the carbon monoxide stable isotope concentrator and the carbon monoxide stable isotope - Google Patents

Description

The present invention relates to a carbon monoxide stable isotope concentrator and a method for operating a carbon monoxide stable isotope device.

There are two types of stable isotopes of ^{carbon, 12} C and ^{13 C.} Of these, ^13C is currently used mainly as a tracer in the natural sciences and medical fields.

As a method for concentrating stable isotopes to a high concentration of 99% or more, a technique that combines isotope scrambling with a distillation cascade process is known. Here, the distillation cascade process is a process in which a plurality of distillation columns are connected in a cascade manner, specific components to be concentrated in each distillation column are supplied to adjacent distillation columns, and the distillation columns are further concentrated. The distillation cascade process enables the enrichment of structural isomers and isotopes whose separation factor (specific volatility or relative volatility) is close to 1 and requires a very large number of theoretical plates. In addition, isotope scrambling is an exchange reaction in which atoms constituting a compound are randomly rearranged.

Patent Document 1 describes a technique relating to isotope scrambling. Patent Document 1 employs isotope scrambling by a catalytic reaction.

For the distillation of carbon monoxide, a technique combining the above-mentioned distillation cascade process and the isotope scrambling described in Patent Document 1 has come to be used. ^{In this technique, some of the 12} C ¹⁸ O molecules concentrated in the distillation cascade process are converted to ¹³ C ¹⁸ O by isotope scrambling ⁽¹³ C ¹⁶ O + ¹² C ¹⁸ O → ¹² C ¹⁶ O + ¹³ C ^18). O), isotope scrambled carbon monoxide is further concentrated in a distillation cascade process to more efficiently (in high yields) concentrate ¹³ CO ( ^{total of 13} C ¹⁶ O and ¹³ C ¹⁸ O). To do. By this technique, ^{carbon monoxide obtained in which 13} C ¹⁶ O and ¹³ C ¹⁸ O are concentrated to a high concentration of 99% or more in total is obtained.

However, carbon monoxide obtained by the above-mentioned technique ^{has a high concentration of 13} C ¹⁸ O, which is a combination with ¹⁸ O, which is a stable isotope of oxygen, and has a problem in being used as a tracer in the medical field.

For the above problems, Patent Document ^2, a combination of techniques that the presence proportion of lower ¹⁸ O impairment isotopic molecules containing ^{18 O,} to give a ¹³ CO product with a reduced abundance ratio of 13 ^{C 18} O There is. Specifically, in Patent Document 2, among a plurality of distillation columns connected in cascade, the distillation column between the distillation column arranged at the upstream end and the distillation column arranged at the downstream end is ¹⁸ O. A stable carbon monoxide enricher to which an impaired device is connected is disclosed.

In the carbon monoxide stable isotope concentrator disclosed in Patent Document 2, in a distillation tower to which an ¹⁸ O attenuating device is connected, carbon monoxide enriched with a stable carbon monoxide isotope containing ^{13 C is discharged from the distillation tower. 18} withdrawn to ^O impairment device, ^{18 O} impairment device to an oxidation-reduction reaction in a part of the monoxide carbon isotope molecules containing ^{18 O,} converted to carbon monoxide stable isotope molecules containing ^{16 O, 18} Attenuates carbon monoxide stable isotope molecules, including O.

In the industrial process, a general water-gas shift reaction is used as the redox reaction. The water-gas shift reaction has a positive reaction represented by the following formula (A) and a reverse reaction represented by the following formula (B).
(Positive reaction) ¹³ C ¹⁸ O + H ₂ ¹⁶ O → ¹³ C ¹⁶ O ¹⁸ O + H ₂ ... Equation (A)
(Reverse reaction) ¹³ C ¹⁶ O ¹⁸ O + H ₂ → ¹³ C ¹⁶ O + H ₂ ¹⁸ O ・ ・ ・ Equation (B)

Japanese Patent No. 4467190 JP-A-2018-164884

In the carbon monoxide stable isotope concentrator disclosed in Patent Document 2, since the ¹⁸ O attenuator is located in the middle part of the distillation process, it is a by-product of the water gas shift reaction (H ₂ , H ₂ O or CO ₂ ). May get mixed in the distillation column. Therefore, when operating the carbon monoxide stable isotope concentrator, the impurity concentrations of the above three components, which are by-products, must be constantly controlled.

In addition, among the by-products, H ₂ O and CO ₂ may cause problems such as clogging of the distillation column due to accumulation of impurities that can enter a very small amount in the distillation column due to long-term operation. .. Since the impurities once mixed cannot be removed without heating, the product ¹³ CO accumulated inside for a long time must be discharged.

Generally, in the isotope separation process, the time from when the device is started until the specified amount (collection amount according to specifications, planned value) of the product can be collected (hereinafter, also referred to as "startup time"). Yes) may take months to years.

Further, since the product is not collected during the start-up of the apparatus, ¹³ C ¹⁸ O accumulates in a state higher than the rated value concentration on the downstream side of the distillation column group. Specifically, when ^{production is started when the 13} CO concentration reaches 99% or more, the ¹³ C ¹⁸ O concentration immediately after the start of production becomes about 2 to 5 times the rated value. Therefore, ^{it is conceivable to design the 18} O impairment device so that the impairment processing capacity is increased, but since the ¹³ C ¹⁸ O concentration increases only for a certain period after the start of production, it is excessive after stable operation. It becomes a facility and causes an increase in initial cost.

The present invention has been made in view of the above problems ^{, and by reducing the necessary minimum impairment processing capacity of the 18} O impairment device and the minimum necessary management, the trouble at the time of starting the device is reduced and the start-up time is shortened. It is an object of the present invention to provide a carbon monoxide stable isotope concentrator capable of the above and a method for operating the same.

In order to achieve the above problems, the present invention adopts the following configuration.
[1] A carbon monoxide stable isotope concentrator that concentrates ¹³ C ^{16 O, which is a stable carbon monoxide isotope molecule.}
A group of distillation columns in which a plurality of distillation columns are cascaded to distill a raw material carbon monoxide containing a plurality of types of stable carbon monoxide isotope molecules and concentrate a stable carbon monoxide isotope molecule containing ^{13 C.}
It is connected to a distillation tower located at the downstream end of the distillation tower group, and a part of the stable carbon monoxide isotope molecule containing ¹⁸ O is subjected to an oxidation-reduction reaction to form a stable carbon monoxide isotope molecule containing ^{16 O.} conversion, and ^{18 O} impairment device that impairment monoxide carbon isotope molecules containing ^{18 O,}
A carbon monoxide stable isotope molecule containing ¹³ C is concentrated from the distillation column located between the distillation column located at the downstream end of the distillation column group and the ^{18 O-damaging equipment.} An introduction line that extracts part or all of it and introduces it into the ^{18 O-damaged equipment.}
A derivation line that derives ¹³ C ^{16 O concentrated from the 18} O impairment equipment as a product, and
The ¹⁸ located between the ^O impairment device and the distillation column unit on the downstream side ends arranged distillation column, carbon monoxide stable isotope molecules containing ^{18 O} from the ^{18 O} impairment device is impaired monoxide A carbon monoxide stable isotope concentrator comprising a return line for returning carbon to the distillation column.
[2] A stable isotope molecule of carbon monoxide, which is connected to at least one of the distillation columns other than the one arranged at the downstream end of the group of distillation columns ^{and contains 16 O by isotope scrambling, is added to 18} O. The carbon monoxide stable isotope concentrator according to the preceding item [1], further comprising an isotope scrambler that converts the contained carbon monoxide stable isotope molecule.
[3] A method of operating a carbon monoxide stable isotope concentrator that concentrates ¹³ C ¹⁶ O, which is a carbon monoxide stable isotope molecule.
At the time of starting the carbon monoxide stable isotope concentrator,
In a group of distillation columns in which multiple distillation columns are connected in cascade, raw material carbon monoxide containing a plurality of types of stable carbon monoxide isotope molecules is distilled to concentrate carbon monoxide stable isotope molecules containing ^{13 C.} ,
A part or all of carbon monoxide in which a stable carbon monoxide isotope molecule containing ¹³ C is concentrated is extracted from the distillation towers arranged at the downstream end of the distillation tower group, and is contained in the carbon monoxide. , a portion of the carbon monoxide stable isotope molecules containing ^{18 O,} is converted into carbon monoxide stable isotope molecules containing ^{16 O,} CO stable isotope molecules containing ^{18 O} is impaired monoxide A method for operating a stable carbon monoxide isotope concentrator, which obtains carbon and returns the carbon monoxide to the distillation tower.
[4] After starting the carbon monoxide stable isotope concentrator,
Distillation that distills raw material carbon monoxide containing a plurality of types of carbon monoxide stable isotope molecules and concentrates carbon monoxide stable isotope molecules including ^{13 C in a group of distillation columns in which a plurality of distillation columns are cascaded.} Process and
A part or all of carbon monoxide in which a stable carbon monoxide isotope molecule containing ¹³ C is concentrated is extracted from the distillation towers arranged at the downstream end of the distillation tower group, and is contained in the carbon monoxide. , a portion of the carbon monoxide stable isotope molecules containing ^{18 O,} is converted into carbon monoxide stable isotope molecules containing ^{16 O,} CO stable isotope molecules containing ^{18 O} is impaired monoxide Perform steady operation including ¹⁸ O impairment step to obtain carbon,
The method for operating a stable carbon monoxide isotope concentrator according to the preceding item [3], ^{wherein the concentrated 13} C ¹⁶ O after the impairment step is derived as a product.

According to the carbon monoxide stable isotope concentrator of the present invention and its operation method, troubles at the time of starting the device can be reduced by the minimum necessary impairment processing capacity of ^{the 18 O impairment device and the minimum necessary management.} The startup time can be shortened.

It is a system diagram which shows the main part of the carbon monoxide stable isotope enrichment apparatus which concerns on embodiment of this invention. It is a system diagram which shows the main part of the carbon monoxide stable isotope enrichment apparatus used in the comparative example 1. FIG.

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 description, in order to make the features easy to understand, the featured parts may be enlarged for convenience, and the dimensional ratio of each component may not be the same as the actual one. Absent.

<Carbon monoxide stable isotope concentrator>
FIG. 1 is a system diagram showing a main part of a carbon monoxide stable isotope concentrator according to an embodiment of the present invention.
The carbon monoxide stable isotope concentrator 100 of the present embodiment includes a group of distillation columns in which 13 distillation columns 1 to 13 are cascaded, an isotope scrambler 20, 13 capacitors 21, and 13 distillation columns. Riboiler 22, ¹⁸ O impaired device 23, analyzer 24, raw material supply line 30, ¹⁸ O impaired device gas introduction line 31, product out-licensing line 32, ¹⁸ O impaired device gas return line 33, and isotopes. A concentrated gas extraction line 34 and an isotope concentrated gas return line 35 are provided.
Hereinafter, the nth distillation column from the upstream end of the distillation column group is referred to as the nth distillation column.
In FIG. 1, among the first to thirteenth distillation columns 1 to 13, the first distillation column 1 and the fourth distillation column to which high-purity carbon monoxide as a raw material is supplied are shown in FIG. Only 4 and the 9th to 13th distillation columns 9 to 13 are shown.

The first to thirteenth distillation columns 1 to 13 are a first distillation column 1, a second distillation column 2, a third distillation column 3, and a fourth distillation to which high-purity carbon monoxide as a raw material is supplied. Tower 4, Fifth Distillation Tower 5, Sixth Distillation Tower 6, Seventh Distillation Tower 7, Eighth Distillation Tower 8, Ninth Distillation Tower 9, Tenth Distillation Tower 10, Eleventh Distillation Tower The eleventh, the twelfth distillation column 12, and the thirteenth distillation column 13 (distillation column at the downstream end of the distillation column group) are cascade-connected in this order.

The first to thirteenth distillation columns 1 to 13 concentrate carbon monoxide isotope molecules having a low boiling point on the top side of the column by low-temperature distillation of carbon monoxide (performing a distillation cascade process), and the bottom side of the column. It is designed to concentrate carbon monoxide isotope molecules with a high boiling point.
Of the first to thirteenth distillation columns 1 to 13, the fourth distillation column 4 to which the raw material is supplied has the largest distillation load, and therefore has the largest diameter. Further, the distillation load is gradually reduced from the fourth distillation column 4 toward the upstream end and the downstream end (the diameter of the column is decreasing).
A rectification stage (shelf), a regular filler, an irregular filler, and the like (none of which are shown) are provided in the first to thirteenth distillation columns 1 to 13, respectively.

One capacitor 21 is provided for each distillation column (first to thirteenth distillation columns 1 to 13).
The condenser 21 is provided on a circulation line 36 whose ends are connected at different positions on the top of each distillation column. The condenser 21 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 this example, a heat medium fluid circulation line 39 that circulates the heat medium fluid through a plurality of capacitors 21 is provided, and heat exchange is performed by the heat medium fluid that circulates in the heat medium fluid circulation line 39. ing.

One reboiler 22 is provided for each distillation column.
The reboiler 22 is provided on a circulation line 37 in which both ends are connected at different positions on the bottom of each distillation column. The reboiler 22 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. In this example, a heat medium fluid circulation line 40 that circulates the heat medium fluid through the plurality of reboilers 22 is provided, and heat exchange is performed by the heat medium fluid that circulates in the heat medium fluid circulation line 40. ing.

One end of the raw material supply line 30 is connected to the intermediate portion of the fourth distillation column 4. The raw material supply line 30 is a line for supplying high-purity carbon monoxide (raw material carbon monoxide) to the intermediate portion of the fourth distillation column 4. The raw material supply line 30 is provided with a valve.
The middle portion of the distillation column indicates a position other than the top and bottom of the distillation column.
High purity means that the total purity of carbon monoxide is 99.999% or more.
The high-purity carbon monoxide supplied from the raw material supply line 30 contains 6 types of stable isotope molecules shown in Table 1 below. In addition, the abundance ratio of each stable isotope molecule is usually the same as the natural abundance ratio shown in Table 1.

One end of the isotope concentrated gas extraction line 34 is connected to the intermediate portion of the tenth distillation column 10, and the other end is connected to the isotope scrambler 20. A valve is provided in the isotope concentrated gas extraction line 34.
When the valve is open, the isotope concentrated gas extraction line 34 derives a part or all of carbon monoxide from the middle part of the tenth distillation column 10 and supplies it to the isotope scrambler 20. ing.
Carbon monoxide derived from the intermediate portion of the tenth distillation column 10 was concentrated by distillation column 10 in the first to ^tenth, the carbon monoxide stable isotope molecules ^{(13 C 16} O containing ¹³ C , ¹³ C ¹⁸ O, etc.). Also, ^{usually, 12} carbon monoxide stable isotope molecules comprising ^{C (12 C 16 O, 12} C 18 O , etc.) are also included.

The isotope scrambler 20 converts a ^{carbon monoxide stable isotope molecule containing 16} O into a carbon monoxide stable isotope molecule ^{containing 18} O by an isotope exchange reaction (isotope scrambling). As a result, a concentrate having a further increased concentration of ¹³ C ^{18 O can be obtained.} It is returned to the distillation column from the isotope concentrated gas return line 35.

One end of the isotope concentrated gas return line 35 is connected to the isotope scrambler 20, and the other end is connected to the intermediate portion of the tenth distillation column 10. A valve is provided in the isotope concentrated gas return line 35.
When the valve was open, the isotope enriched gas return line 35 ^{derived a concentrate having a further increased concentration of 13} C ¹⁸ O from the isotope scrambler 20 to the tenth distillation column 10 (carbon monoxide was derived. Return to the middle part of the distillation column).
The carbon monoxide returned to the tenth distillation column 10 is distilled in the eleventh to thirteenth distillation columns 11 to ^13, and the carbon monoxide stable isotope molecule containing 13 C is further concentrated.

^{The 18} O impairment device gas introduction line (introduction line) 31 is located between the 13th distillation column 13 arranged at the downstream end of the distillation column group and the ¹⁸ O impairment device 23. ^{One end of the 18} O impairment device gas introduction line 31 is connected to the lower part of the thirteenth distillation column 13, and the other end is ^{connected to the 18} O impairment device 23. ^{The 18} O attenuator gas introduction line 31 extracts a part or all of the carbon monoxide stable isotope molecule-enriched carbon monoxide including ^{the 13th distillation column 13 to 13 C into the 18} O attenuator 23. Introduce.

^{The 18} O depletion device 23 utilizes an aqueous gas shift reaction including a positive reaction represented by the following formula (1) and a reverse reaction represented by the following formula (2), and contains, for example, a proportion of ¹⁸ O larger than the natural abundance ratio. A part of carbon monoxide stable isotope molecules ( ¹³ C ¹⁸ O, ¹² C ¹⁸ O, etc.) is converted into carbon monoxide stable isotope molecules containing ¹⁶ O, and carbon monoxide stable isotope molecules containing ^{18 O.} Is impaired.

・ Water-gas shift reaction (positive reaction) ¹³ C ¹⁸ O + H ₂ ¹⁶ O → ¹³ C ¹⁶ O ¹⁸ O + H ₂ ... Equation (1)
(Reversible reaction) ¹³ C ¹⁶ O ¹⁸ O + H ₂ → ¹³ C ¹⁶ O + H ₂ ¹⁸ O ・ ・ ・ Equation (2)

Specifically, ^{in the forward reaction, 13} C ¹⁶ O ¹⁸ O is produced by reacting with water having a high natural abundance ratio of ^{16 O introduced into the 18} O impairment device 23, and in the reverse reaction, ¹³ C ¹⁶ O is further produced. By generating, as a result, some ¹³ C ¹⁸ O can be converted into ¹³ C ^{16 O.}

^{The 18} O impairment device 23 _{is provided with a reactant discharge route 38 for separating the generated CO 2} , H ₂ O, and H ₂ reactants from carbon monoxide and discharging them to the outside of the apparatus. Examples of the method for separating carbon monoxide and the reactant include condensation separation, adsorption, membrane separation, distillation and the like.

The product out-licensing line (out-licensing line) 32 is ^{a route for out-licensing the concentrated 13} C ¹⁶ O as a product ^{from the 18} O impairment device 23 during stable operation (steady operation). One end of the product lead-out line 32 is ^{connected to the 18} O impairment device 23. ^{The 13} CO product is carbon monoxide containing ¹³ C ¹⁶ O concentrated to a high concentration (eg, 99% or more) ^{and 13} C ^{18 O.} The carbon monoxide in the product lead-out line 32 is a stable carbon monoxide isotope molecule containing ^{18 O (12} C ¹⁸ O, ¹³ C ¹⁸ O) as compared with the time when it was led out from the thirteenth distillation tower 13. There is ^impaired, and is converted into carbon monoxide stable isotope molecules ^{(12 C 16 O, 13 C} 16 O) containing ¹⁶ O.

The analyzer 24 is branched from the product out-licensing line 32 in order to perform a trace analysis of _{CO 2} , H ₂ O, and H ₂ ^{contained in carbon monoxide led out from the 18} O impairment device 23 to the product out-licensing line 32. Is provided. Examples of the analyzer 24 include a gas chromatograph, an infrared spectroscope, a mass spectrometer, and the like.

^{The 18} O impairment device gas return line (return line) 33 is located between the ¹⁸ O impairment device 23 and the thirteenth distillation column 13 arranged at the downstream end of the distillation column group. ^{One end of the 18} O impairment device gas return line 33 is ^{connected to the product lead-out line 32 on the secondary side of the 18} O impairment device 23 (branched from the product lead-out line 32). ^{The other end of the 18} O impairment device gas return line 33 is connected to the lower part of the thirteenth distillation column 13. ^{18 O} impairment device gas return line 33, at the time of startup of carbon monoxide stable isotope enrichment apparatus 100, ^{18 O} impairment device 23 by carbon monoxide carbon monoxide stable isotope molecule is impaired including ^{18 O} 13 It is a route for returning to the distillation tower 13 of.

The product lead-out line 32 and the 18O impairment device gas return line (return line) 33 are provided with flow path switching means (for example, an on-off valve or the like) (not shown), and flow paths are provided independently or in conjunction with each other. It is possible to select the opening and closing of.

<Operation method of carbon monoxide stable isotope concentrator>
Next, a method of operating the carbon monoxide stable isotope concentrator according to the embodiment of the present invention will be described with reference to FIG. ^{In this embodiment, 13} CO is concentrated using the carbon monoxide stable isotope concentrator 100 shown in FIG.

(At startup)
First, when starting the carbon monoxide stable isotope concentrator 100 of the present embodiment, ^{it is confirmed that the 18} O impairment device gas return line 33 is opened and the product lead-out line 32 is closed.
Next, in the carbon monoxide stable isotope concentrator 100, the raw material carbon monoxide containing a plurality of types of carbon monoxide stable isotope molecules is distilled in a group of distillation towers in which a plurality of distillation towers are cascaded. Concentrate carbon monoxide stable isotope molecules containing ^{13 C.}

Next, carbon monoxide stable isotope molecules containing ¹³ C were concentrated from the thirteenth distillation column 13 arranged at the downstream end of the distillation column group via the ¹⁸ O impairing device gas introduction line 31. some or extracts all, introduced into ^{18 O} impairment device 23.

^{In the 18} O attenuating device 23, a part of the carbon monoxide stable isotope molecule containing ¹⁸ O contained in the carbon monoxide is converted into a carbon monoxide stable isotope molecule containing ^{16 O, and contains 18} O. A carbon monoxide stable isotope molecule is obtained with impaired carbon monoxide. ^{The obtained carbon monoxide is returned from the 18} O impairment device 23 to the thirteenth distillation column 13 via the product lead-out line 32 and the ¹⁸ O impairment device gas return line 33.

In this way, the ¹⁸ O impaired device 23 is operated to obtain carbon monoxide in which the stable carbon monoxide isotope molecule is impaired, and this carbon monoxide is transferred from the ¹⁸ O impaired device 23 to the thirteenth distillation tower 13. By returning the carbon monoxide stable isotope concentrator 100, the concentration of ¹³ C ¹⁸ O in the thirteenth distillation column 13 can be reduced to the rated value or less when the carbon monoxide stable isotope concentrator 100 is started. Therefore, ^{the impairment processing capacity of the 18} O impairment device 23 can be minimized.

On the other hand, when the equipment is started, the ¹⁸ O depletion equipment 23 is operated, and the obtained carbon monoxide is ^{returned from the 18} O depletion equipment 23 to the thirteenth distillation column 13, thereby producing a by-product of the water gas shift reaction (H _2). , H ₂ O or CO ₂ ) may be mixed in the distillation column. Therefore, the analyzer 24 controls the concentration of by- _{products (CO 2} , H ₂ O, H ₂ ) in the carbon monoxide derived from the ^{18 O impairment device 23.} This makes it possible to reduce the possibility of impurities accumulating in the thirteenth distillation column 13.

When the specified amount (collection amount according to specifications, planned value) of ¹³ CO products can be collected on the product out-licensing line 32, the start-up of the carbon monoxide stable isotope concentrator 100 is completed, and ¹⁸ O through the impairment device gas return line 33 ^to end the return from ¹⁸ O impairment device 23 to the distillation column 13 of the 13. By terminating the return to the distillation column, there is no possibility that by-products of the aqueous gas shift reaction will be mixed into the distillation column, so to prevent impurities from accumulating in the distillation column and clogging the distillation column. It is not necessary to constantly control the impurity concentration.

(During steady operation)
Next, after starting the carbon monoxide stable isotope concentrator 100, the ¹⁸ O impairment device gas return line 33 is closed, the product lead-out line 32 is opened, and the flow path is switched. Next, in the carbon monoxide stable isotope concentrator 100, a ^{steady operation including a distillation step and an 18} O impairment step is performed.

In the distillation step, high-purity carbon monoxide (a plurality of types of monoxide) supplied from the raw material supply line 30 to the fourth distillation column 4 of the distillation column group in which the first to thirteenth distillation columns 1 to 13 are cascade-connected. Raw material carbon monoxide containing carbon stable isotope molecules) is distilled in the distillation column groups (1st to 13th distillation columns 1 to 13) to concentrate carbon monoxide stable isotope molecules containing ^{13 C.} ..

^{In the 18} O impairment step, first, a part or all of carbon monoxide in which carbon monoxide stable isotope molecules including ¹³ C are concentrated from the thirteenth distillation column 13 arranged at the downstream end of the distillation column group. ^extracting, introduced through ¹⁸ O impairment device gas inlet line 31 to the ¹⁸ O impairment device 23. ^{Next, the stable carbon monoxide isotope molecule containing 18} O contained in the carbon monoxide is subjected to an aqueous gas shift reaction including a positive reaction represented by the above formula (1) and a reverse reaction represented by the formula (2). Then, it is converted into a carbon monoxide stable isotope molecule containing ^{16 O, and the carbon monoxide stable isotope molecule containing 18} O is impaired to obtain carbon monoxide.

^{Next, the concentrated 13} C ¹⁶ O after the impairment step is taken out as a product from the product out-licensing line 32. From ¹⁸ O impairment device 23 is derived through the product outlet line ^{32, 18} O concentration of ¹³ C is a high concentration, for example, isotopes concentration of ¹³ C enriched over 99% ¹³ CO in the product is utilized as a tracer Therefore, it is sufficiently low, for example, the ¹⁸ O isotope concentration is 5% or less.

In the carbon monoxide stable isotope concentrator 100 described above, since the ¹⁸ O impairment device 23 is connected to ^{the thirteenth distillation column 13 arranged at the downstream end, 13} CO can be efficiently concentrated. ..
Further, the obtained ¹³ CO product contains ¹³ C ¹⁶ O in a high concentration, and ^{the abundance ratio of 13} C ¹⁸ O is not too high as compared with the natural abundance ratio, so that it is useful as a tracer in the medical field and the like.

Further, in the above-described method of operating the carbon monoxide stable isotope concentrator 100, the ¹⁸ O depletion device 23 is operated at the time of start-up to obtain carbon monoxide in which the carbon monoxide stable isotope molecule is impaired. Since carbon monoxide is ^{returned from the 18} O depletion device 23 to the thirteenth distillation column 13, the ^{concentration of 13} C ¹⁸ O in the thirteenth distillation column 13 should be kept below the rated value until the start of steady operation. Can be done. Therefore, ^{the impairment processing capacity of the 18} O impairment device 23 can be minimized.

On the other hand, apparatus ^{18 O} impairment device 23 runs at startup, for returning from carbon monoxide ^{18 O} impairment device 23 obtained into the distillation column 13 of the 13, by-products of the water gas shift reaction (H _2, H ₂ O or CO ₂ ) may be mixed in the distillation column. According to the operating method of the carbon monoxide stable isotope concentrator 100 of the present embodiment, the by- _{products (CO 2} , H ₂ O, H) in carbon monoxide derived from the ^{18 O depletion device 23 by the analyzer 24} _{By controlling the concentration of 2} ), the possibility of accumulation of impurities in the thirteenth distillation column 13 can be reduced. Therefore, troubles at the time of starting the device can be reduced, and the start-up time can be shortened.

Although the carbon monoxide stable isotope concentrator of the present invention and the operation method thereof have been described above by showing the 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 can be made without departing from the spirit of the present invention.
For example, the number of distillation columns (cascade-connected distillation columns) constituting the distillation column group is not limited to 13, and can be any number. The distillation column is not limited to a filling column filled with a regular filling, and may be a filling tower or a shelf column filled with an irregular filling.
The isotope scrambler is not limited to the tenth distillation column 10, and may be a distillation column other than the tenth distillation column 10. However, at least one of the distillation columns to which the isotope scrambler is connected is a distillation column other than the distillation column arranged at the downstream end of the distillation column group.
^A plurality of 18 O impairment devices may be connected in series.
^{The 18} O impairment device may be connected to a plurality of distillation columns, including a distillation column located at the downstream end of the group of distillation columns.
The above-mentioned condenser 21 and reboiler 22 are not indispensable for each distillation column, and may not be provided when the gas rise is sufficient due to the pressure difference between the front and rear distillation columns, the pump, the blower, and the like.

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, 13} C ¹⁶ O was concentrated using the carbon monoxide stable isotope concentrator 100 shown in FIG. The composition of the raw material carbon monoxide to be supplied is as shown in Table 1 above.
Simultaneously with the activation of the apparatus, the extraction of carbon monoxide from the 10th distillation column 10, the isotope scramble in the isotope scrambler 20, and the return from the isotope scrambler 20 to the 10th distillation column 10 were started. .. Similarly, extraction of carbon monoxide from the distillation column 13 of the ^{13, 18} O impairment device 23 in ¹⁸ O ^impairment, via ¹⁸ O impairment device 23 from ¹⁸ O impairment device gas return line 33 13th distillation column The return to 13 has started.
^{The time (startup time) until the 13} CO concentration in the lower part of the thirteenth distillation column 13 reached 99% or more was about 4.5 months.

^{13 After the} CO concentration reached 99% or more, ^{the gas supply from the 18} O impairment device 23 to the ¹⁸ O impairment device gas return line 33 was stopped, and the production of product gas was started from the product line 32. Table 2 shows the abundance ratio of stable isotope molecules of the ¹³ CO product delivered from the thirteenth distillation column 13 immediately after the start of product gas production and when the apparatus is stable (steady operation).
Immediately after the start of the product gas supply means immediately after the start of extracting the gas from the product gas line 32.
^{The 13} CO concentration means the total concentration of ¹³ C ¹⁶ O, ¹³ C ¹⁷ O, and ¹³ C ^{18 O.
The 18} O concentration means the total concentration of ¹² C ¹⁸ O and ¹³ C ^{18 O.}

(Comparative Example 1)
^{In Comparative Example 1, 13} CO was concentrated using the carbon monoxide stable isotope concentrator 200 shown in FIG. The carbon monoxide stable isotope concentrator 200 is the same as the carbon monoxide stable isotope concentrator 100 except that there is no ^{18 O depletion device gas return line 33.}
As in the first embodiment, at the same time as starting the apparatus, extraction of carbon monoxide from the tenth distillation column 10, isotope scramble in the isotope scrambler 20, and isotope scrambler 20 to the tenth distillation column 10 Started returning to.
^{The 18} O impairment apparatus used had the same impairment processing capacity as in Example 1. ^{It took about 4 months for the 13} CO concentration in the lower part of the 13th distillation column 13 to reach 99% or more.
^{13 After the} CO concentration reached 99%, gas was extracted from the product line 32 (production started). ^It took another two months for the 18 O concentration to reach the same level as in Example 1.
Table 3 shows the abundance ratios of stable isotope molecules of the ¹³ CO products delivered from the thirteenth distillation column 13 when the product gas supply was started and when the apparatus was stabilized.

In Example 1, only one gas line was added from the apparatus of Comparative Example 1, and the ¹⁸ O concentration in the product could be kept low both immediately after the start of product gas production and when it was stable.

In Example 1, ^{it took 4.5 months for the 13} CO concentration to reach 99% or higher. The reason why it took 0.5 months longer than Comparative Example 1 is that ¹⁸ O was attenuated by the ¹⁸ O attenuator, and ^{carbon monoxide containing 16} O was more than the stable carbon monoxide isotope molecule containing ^{18 O.} Since stable isotope molecules are less likely to be concentrated at the downstream end of the distillation tower group, it is probable that it took longer to concentrate ^{13 CO.}
However, in Example 1, with concentration of ^{13 CO, 18 O} impairment apparatus for performing the impairment operation ^{18 O,} the time to obtain a product gas as a useful as a tracer, as compared with Comparative Example 1, 1 I was able to shorten it by 5 months.

By the way, the general life cycle of a conventional distillation apparatus (see, for example, Patent Document 2) is 30 years or more. That is, in the conventional distillation apparatus, the concentration of by- _{products (CO 2} , H ₂ O, H ₂ ) in the water gas shift reaction ^{is constantly controlled in the distillation column to which the 18 O impairment apparatus is connected for 30 years or more.} There is a need.
On the other hand, in Example 1 of the present invention, the start-up time is about 4.5 months. Furthermore, after the activation, since the return to the distillation column ends, since by-products in the water gas shift reaction will not be incorporated, ¹⁸ in ^O impairment device connected distillation column, impurities accumulate in the distillation column It is not necessary to constantly control the concentration of by-products in the aqueous gas shift reaction in order to prevent the distillation column from clogging.

The present invention is a distillation apparatus for distilling an ultra-low temperature fluid, and uses a distillation apparatus provided with a group of distillation columns in which a plurality of distillation columns are cascaded, and is stable in carbon monoxide, which exists in a very small amount in nature. applicable to isotope molecule ^{(13 C} 16 ^O) CO isotope enrichment apparatus and carbon monoxide stable isotope enrichment method for concentrating.

1, 4, 9, 10, 11, 12, 13 ... Distillation column 20 ... Isotope scrambler 21 ... Condenser 22 ... Ribola 23 ... ¹⁸ O Impairment equipment 24 ... Analyzer 30 ... Raw material supply line 31 ... ¹⁸ O Impairment equipment Gas introduction line (introduction line)
32 ... Product out-licensing line (out-licensing line)
33 ... ¹⁸ O Impairment device Gas return line (return line)

Claims (4)

A carbon monoxide stable isotope concentrator that concentrates ¹³ C ¹⁶ O, which is a carbon monoxide stable isotope molecule.
A group of distillation columns in which a plurality of distillation columns are cascaded to distill a raw material carbon monoxide containing a plurality of types of stable carbon monoxide isotope molecules and concentrate a stable carbon monoxide isotope molecule containing ^{13 C.}
It is connected to a distillation tower located at the downstream end of the distillation tower group, and a part of the stable carbon monoxide isotope molecule containing ¹⁸ O is subjected to an oxidation-reduction reaction to form a stable carbon monoxide isotope molecule containing ^{16 O.} conversion, and ^{18 O} impairment device that impairment monoxide carbon isotope molecules containing ^{18 O,}
A carbon monoxide stable isotope molecule containing ¹³ C is concentrated from the distillation column located between the distillation column located at the downstream end of the distillation column group and the ^{18 O-damaging equipment.} An introduction line that extracts part or all of it and introduces it into the ^{18 O-damaged equipment.}
A derivation line that derives ¹³ C ^{16 O concentrated from the 18} O impairment equipment as a product, and
The ¹⁸ located between the ^O impairment device and the distillation column unit on the downstream side ends arranged distillation column, carbon monoxide stable isotope molecules containing ^{18 O} from the ^{18 O} impairment device is impaired monoxide A carbon monoxide stable isotope concentrator comprising a return line for returning carbon to the distillation column. It is connected to at least one of the distillation columns other than the distillation column located at the downstream end of the distillation column group, and isotope scrambling is performed to obtain a stable carbon monoxide isotope molecule containing ^{16 O and monoxide containing 18} O. The stable carbon monoxide isotope concentrator according to claim 1, further comprising an isotope scrambler that converts a stable carbon isotope molecule. It is a method of operating a carbon monoxide stable isotope concentrator that concentrates ¹³ C ¹⁶ O, which is a carbon monoxide stable isotope molecule.
At the time of starting the carbon monoxide stable isotope concentrator,
In a group of distillation columns in which multiple distillation columns are connected in cascade, raw material carbon monoxide containing a plurality of types of stable carbon monoxide isotope molecules is distilled to concentrate carbon monoxide stable isotope molecules containing ^{13 C.} ,
A part or all of carbon monoxide in which a stable carbon monoxide isotope molecule containing ¹³ C is concentrated is extracted from the distillation towers arranged at the downstream end of the distillation tower group, and is contained in the carbon monoxide. , a portion of the carbon monoxide stable isotope molecules containing ^{18 O,} is converted into carbon monoxide stable isotope molecules containing ^{16 O,} CO stable isotope molecules containing ^{18 O} is impaired monoxide A method for operating a stable carbon monoxide isotope concentrator, which obtains carbon and returns the carbon monoxide to the distillation tower. After starting the carbon monoxide stable isotope concentrator,
Distillation that distills raw material carbon monoxide containing a plurality of types of carbon monoxide stable isotope molecules and concentrates carbon monoxide stable isotope molecules including ^{13 C in a group of distillation columns in which a plurality of distillation columns are cascaded.} Process and
A part or all of carbon monoxide in which a stable carbon monoxide isotope molecule containing ¹³ C is concentrated is extracted from the distillation towers arranged at the downstream end of the distillation tower group, and is contained in the carbon monoxide. , a portion of the carbon monoxide stable isotope molecules containing ^{18 O,} is converted into carbon monoxide stable isotope molecules containing ^{16 O,} CO stable isotope molecules containing ^{18 O} is impaired monoxide Perform steady operation including ¹⁸ O impairment step to obtain carbon,
The method for operating a stable carbon monoxide isotope concentrator according to claim 3, ^{wherein the concentrated 13} C ¹⁶ O after the impairment step is derived as a product.

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