JP2002220206A - Method and device for concentration and separation of hydrogen isotope - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a compact device easy to operate and a method for hydrogen isotope concentration and separation capable of concentrating and separating deuterium at a high concentration rate or at a high recovery rate from a raw hydrogen gas consisting of mixed protium and deuterium. SOLUTION: This method and device consist of an absorption process which comprises placing three and more absorption towers side by side filled in with an absorbing agent to preferentially absorb protium, sequentially keeping one absorption tower standby and connecting the remaining towers in series and supplying a raw gas through the bottom of the rearmost tower to be absorbed by the absorbing agent, a reprocessing process which comprises cutting off the rearmost tower from the series after completion of absorption, producing an increase in temperature to desorb a protium-enriched gas and thus reprocessing the absorbing agent and keeping it standby and a recovery process to recover an enriched deuterium through the top of the headmost tower after repeating the absorption and reprocessing processes.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for concentrating and separating hydrogen isotopes for recovering deuterium from a gas in which light hydrogen and deuterium are mixed, and an apparatus used for the method.

[0002]

2. Description of the Related Art In addition to a hydrogen atom having a mass number of 1 (H), a hydrogen atom having a mass number of 2 (deuterium: D) and a hydrogen atom having a mass number of 3 (tritium: T) isotopes, and various commonly available hydrogen gas raw materials include, in addition to hydrogen gas composed of H ₂ (herein referred to as light hydrogen), a trace amount of HD containing deuterium as a constituent atom. , D ₂ and tritium as constituent atoms, and a very small amount of hydrogen gas composed of HT, DT, and T ₂ (in the present specification, these are collectively referred to as deuterium). Deuterium is a valuable substance for various uses such as tracers for analysis and analysis, as well as fuel for fusion reactors, but as described above, it is mixed with light hydrogen, so it is provided for each use. In order to
Attempts have been made to separate light hydrogen and deuterium by a conventionally known thermal diffusion method, distillation method, laser method, membrane separation method or the like. However, these methods have disadvantages such as a large device and a large amount of operating energy.

In contrast to these methods, a method using an occluding agent (adsorbent) that preferentially occupies (adsorbs) a specific hydrogen isotope can separate the hydrogen isotope with a relatively simple apparatus. Although there is an advantage, the conventional occlusion method (adsorption method)
Thus, there was a problem that the enrichment rate or the recovery rate of the target hydrogen isotope was low, and a low-concentration hydrogen isotope could not be extracted at a high concentration.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to overcome the problems described above and to obtain a high enrichment or recovery rate from isotope-mixed hydrogen gas by using a small and easy-to-operate apparatus. Another object of the present invention is to provide a new hydrogen isotope enrichment and separation technique capable of enriching and separating deuterium by using the method.

[0005]

According to the present invention, there is provided, as a means for achieving the above-mentioned object, a method for concentrating and separating deuterium from a source gas in which deuterium is mixed with light hydrogen;
N (n ≧ n) filled with an occluding agent that preferentially occupies light hydrogen
The storage towers of 3) are juxtaposed, and one storage tower is sequentially put on standby, and the remaining (n-1) storage towers are connected in series to form (n-
1) An occlusion step in which a raw material gas is supplied from a lower end of the last occlusion tower of the occlusion tower to occlude the gas in the occluding agent, and after the occlusion step is completed, the (n-1) occlusion is performed. After the storage tower at the end of the tower is disconnected from the connection and the temperature is raised to release the light hydrogen-enriched gas to regenerate the storage agent and wait. 1)
Provided is a method for enriching and separating hydrogen isotopes, which includes a recovery step of recovering concentrated deuterium from the upper end of the top storage tower of the book storage tower.

Further, according to the present invention, there is provided an apparatus used for carrying out the above-mentioned method for enriching and separating hydrogen isotopes, wherein an occluding agent for preferentially occluding light hydrogen is filled and a temperature adjusting means is provided. At least three occlusion towers; an occlusion tower connection passage connecting the upper end of each occlusion tower and the lower end of the next occlusion tower; a source gas supply path and a source gas divided from the source gas supply path and provided at a lower end of each occlusion tower. Gas exhaust path for exhausting light hydrogen-enriched gas from the lower end of each storage tower to a storage vessel; Concentrated weight for extracting concentrated deuterium from the upper end of each storage tower and collecting it in the storage vessel Hydrogen recovery path; a source gas flow path switching valve that is provided at a branch point between the source gas supply path and the source gas introduction path and that is switched to guide the source gas to the source gas introduction path of one of the storage towers; Located below,
A storage tower lower flow path switching valve that is switched to connect the lower end of each storage tower to one of a storage tower connection passage, a raw material gas introduction passage, and an exhaust gas recovery passage; provided above each storage tower; A hydrogen isotope enrichment / separation device having an occlusion tower upper flow path switching valve that is switched to connect the upper end of the occlusion tower to either the occlusion tower connection passage or the enriched deuterium recovery passage.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention provides a method for separating hydrogen isotopes using an occluding agent (adsorbent) by juxtaposing three or more occlusion towers filled with an occluding agent that occludes light hydrogen preferentially. The isotope effect of the occluding agent is obtained by sequentially moving the occlusion tower for occlusion and desorption of light hydrogen (that is, regeneration of the occluding agent) only by switching the flow path by opening and closing the valve (valve) and adjusting the temperature. This makes it possible to concentrate deuterium in the occlusion tower located at the head and to recover it at a high concentration rate. Hereinafter, in order to facilitate understanding, embodiments of the present invention will be described in detail along the hydrogen isotope enrichment and separation apparatus of the present invention illustrated in FIG.

[0008] The hydrogen isotope enrichment and separation apparatus of the present invention has n (n ≧ n) filled with an occluding agent that preferentially occupies light hydrogen.
The storage tower of 3), that is, at least three storage towers are juxtaposed. The storage tower is provided with a temperature adjusting means so that a light hydrogen-containing gas is stored in the storage agent and the gas is desorbed from the storage agent as described later. In the apparatus illustrated in FIG. 1, three storage towers filled with a storage agent (1) that stores light hydrogen preferentially, that is, a first storage tower (2), a second storage tower (3), and a second storage tower (3). Three storage towers (4) are juxtaposed.

Each of the storage towers is configured such that an upper end thereof is connected to a lower end of the next storage tower by a storage tower connection passage, and can be connected in series during a hydrogen isotopic enrichment and separation operation. In the example of the apparatus of FIG. 1, (15), (16) and (17) represent the first storage tower-second storage tower connection passage, the second storage tower-third storage tower connection passage, and the third storage tower, respectively. It becomes a tower-first storage tower connection passage.

A source gas supply path for supplying a source gas in which deuterium is mixed with light hydrogen is provided below each of the storage towers. A source gas introduction path for introducing the source gas is provided. In the device illustrated in FIG. 1, (10)
Is a source gas supply path, and (9) divided therefrom corresponds to a source gas introduction path. As shown in the figure, it is preferable that a mass flow controller for adjusting the pressure and the flow rate so as not to be imbalanced is provided in the source gas supply path.

An exhaust gas recovery path is provided below each of the storage towers for exhausting and recovering the light hydrogen-enriched gas from its lower end when the storage agent is regenerated as described below. In the apparatus illustrated in FIG. 1, (24) is an exhaust gas recovery path. As shown in the figure, an on-off valve (25), a needle valve (26), and a mass flow controller (27) are installed in the exhaust gas recovery path, and desorption discharged from the exhaust gas recovery path (24) is performed. The gas (light hydrogen-enriched gas) is collected and stored in an exhaust gas collection container (28).

As shown in FIG. 1, the exhaust gas recovery path is preferably connected to a vacuum exhaust means via an appropriate on-off valve (29). As a result, as described later, after the light hydrogen-enriched gas is desorbed in the storage agent regeneration step, the evacuation is further performed, whereby the regeneration (activation) of the storage agent is promoted, and light hydrogen and deuterium are decomposed. Is increased.

On the other hand, above each occlusion tower, a concentrated deuterium recovery passage for repeating the storage step and the regeneration step as described later, and then leading the concentrated deuterium from the upper end thereof and collecting it in the storage container is provided. It is arranged. In the device example of FIG.
(18) is a concentrated deuterium recovery path. As shown in the figure, the concentrated deuterium recovery path includes an on-off valve (19), a pressure gauge (23), a needle valve (20), and a mass flow controller (21). , And a deuterium recovery storage container (22) is connected to the tip thereof.

The hydrogen isotope enrichment / separation apparatus of the present invention is further provided with some flow path switching valves, and by appropriately switching the above-mentioned various paths (flow paths), the hydrogen isotope is separated. Isotope enrichment and separation can be performed easily and efficiently.

That is, at a branch point between the source gas supply path and the source gas introduction path, a source gas flow path switching valve that switches so as to guide the source gas to the source gas introduction path of one of the storage towers is provided. In the example shown in FIG. 1, (8) is this source gas flow path switching valve. Below the storage tower, a storage tower lower flow path switching valve that switches the lower end of each storage tower to be connected to the storage tower connection passage, the raw material gas introduction passage, or the exhaust gas recovery passage is arranged. In the apparatus shown in FIG. 1, (5), (6) and (7) correspond to the first occlusion tower (2), the second occlusion tower (3) and the third occlusion tower, respectively.
This is a flow path switching valve provided below the storage tower (4). Above each storage tower, a storage tower upper flow path switching valve that switches the upper end of each storage tower to be connected to either the storage tower connection passage or the concentrated deuterium recovery passage is provided. 1, (12), (13) and (14) are provided above the first storage tower (2), the second storage tower (3) and the third storage tower (4), respectively. It is a flow path switching valve provided.

The occluding agent for preferentially occluding light hydrogen used in the present invention is not particularly limited, and palladium (Pd), Pd-Pt, Pd-Au, Pd-A
g, a palladium alloy-based occluding agent, a zirconium alloy-based occluding agent, a titanium alloy-based occluding agent, uranium (U), and the like can be used. These are used after filling into an occlusion tower with pellets, tablets or powder processed into a suitable size. A preferred example of the occlusion agent is palladium, and palladium alumina pellets having improved durability of palladium are particularly preferred. These occluding agents generally absorb (adsorb) light hydrogen at room temperature and then desorb and release the occluded gas when the temperature is raised (for example, about 200 ° C. in the case of a palladium-based occluding agent). Next, a method for enriching and separating hydrogen isotopes using the above apparatus will be specifically described.

First, as a preliminary operation, the storage tower (2) (3)
(4) is heated and evacuated to activate the occluding agent contained therein. Thereafter, while the on-off valve (19) is closed, the flow path switching valve (5) (12)
The first storage tower (2) and the second storage tower (3) are connected via (6), the flow path switching valve (8) is set in the direction of the first storage tower, and the flow rate is adjusted by the mass flow controller (11). Raw material gas (hydrogen gas mixed with hydrogen isotope) is supplied at room temperature. When the pressure at the outlet of the second storage tower reaches the source gas supply pressure, the flow path switching valves (5), (12), and (6) are closed to disconnect the first storage tower. At the same time, the flow path switching valve (6) (1
3) Open (7), second storage tower (3) and third storage tower (4)
And the flow path switching valve (8) is switched to the second storage tower (3), and the raw material gas whose flow rate has been adjusted by the mass flow controller (11) is supplied at room temperature.

The temperature of the separated first storage tower (2) is raised (for example, up to 200 ° C.), and the stored raw material gas is desorbed. After the temperature of the first storage tower (2) rises to a preset temperature, the flow path switching valve (5) is opened, and the exhaust gas recovery path (24), the on-off valve (25), the needle valve (26) and the mass flow The controller (27) is closed and another on-off valve (29) is opened to evacuate and regenerate the occluding agent (1). When the regeneration step is completed, the on-off valve (29) and the flow path switching valve (5) are closed and put on standby.

When the pressure of the third storage tower (4) reaches the supply pressure of the raw material gas, the flow path switching valves (6), (13) and (7) are closed to disconnect the second storage tower, and at the same time, the flow path switching valve is opened. (7) (1
4) Opening (5), connecting the third storage tower with the first storage tower which has been on standby, switching the flow path switching valve (8) to the third storage tower, and adjusting the flow rate of the raw material by the mass flow controller (11). The gas is supplied at room temperature. The temperature of the disconnected second storage tower is raised (for example, up to 200 ° C.), the stored raw material gas is desorbed, and after the temperature of the second storage tower reaches the set temperature, the flow path switching valve (6) is opened. Open and exhaust to reservoir (28) through exhaust gas recovery path (24). Thereafter, the on-off valve (25) is closed, and the on-off valve (29) is opened to evacuate and regenerate the occluding agent. When this regeneration process is completed, the on-off valve (2
9) and the flow path switching valve (6) are closed and put on standby.

When the pressure at the outlet of the first storage tower reaches the supply pressure of the raw material gas, the flow path switching valves (7), (14) and (5) are closed to disconnect the third storage tower. Open the flow path switching valves (5), (12) and (6), connect the first storage tower and the second storage tower, switch the flow path switching valve (8) to the first storage tower, and use the mass flow controller (11) to control the flow rate. The adjusted source gas is supplied at room temperature. The temperature of the separated third storage tower is raised (for example, up to 200 ° C.), the hydrogen-enriched gas is desorbed, and the temperature at the outlet of the third storage tower reaches the set temperature. ) Is opened and sent to an exhaust gas storage (28) through an exhaust gas recovery path (24). Thereafter, the exhaust is evacuated and the storage agent is regenerated. After the regeneration step is completed, the flow path switching valve (7) is closed and made to wait.

As described above, in the present invention, one of the n storage towers filled with the storage agent is kept on standby, and the remaining (n-1) storage towers are sequentially connected in a state of being connected in series. A storage step in which the raw material gas is supplied from the lower end of the last storage tower of the connected storage tower to occlude the storage agent, and after the storage step is completed, the last storage tower is disconnected from the connection to remove the storage agent. The reproduction step of reproducing is repeated. For example, when three storage towers are juxtaposed as shown in FIG. 1, as described in detail above, two storage towers are sequentially connected, and one storage tower is in a standby state. The process and the regeneration process are repeated.

When this operation is repeated, deuterium in the raw material gas is moved to the leading storage tower, and the deuterium is gradually concentrated. Enough deuterium in the top storage tower,
After concentration to the concentration, one of the flow path switching valves (12), (13), and (14) and the on-off valve (19) at the upper end of the top occlusion tower are opened, and the needle valve (18) is passed through the concentrated deuterium recovery path (18). 20) and mass flow controller (21)
The concentrated deuterium is recovered and stored in the recovery storage container (22) as a product gas while controlling the flow rate by the above. After the product gas is recovered, the hydrogen isotope in the source gas can be continuously concentrated and separated by continuously performing the above-described concentration operation.

In the above embodiment, the concentration and separation are performed using three storage towers. However, when the concentration of hydrogen isotope (deuterium) in the raw material gas is low, or when the concentration of hydrogen isotope (deuterium) is high, Hydrogen) is to be obtained as quickly as possible.
A predetermined concentration may be obtained by arranging and using more than one storage tower. Thus, according to the present invention, by juxtaposing at least three or more storage towers,
A continuous process is possible in which the one storage agent containing the activated (regenerated) storage agent is kept on standby and the remaining storage towers are connected to store the source gas. The greater the number of storage towers connected, the higher the enrichment rate of hydrogen isotopes (deuterium) in the storage tower located at the head thereof, but in practice, generally three to five storage towers may be arranged. .

FIG. 2 shows the results of an experimental example in which natural hydrogen (deuterium concentration: 150 ppm) was concentrated using the apparatus of FIG. 1 described above (the storage agent was palladium alumina pellets) and according to the method of the present invention. The experimental conditions were tower temperature 303
K, the superficial tower speed was 6.8 cm / sec, and the tower height was 70 cm.
m is the number of juxtaposed columns used in the experiment (that is, the number of occlusion towers), and n is the number of passing columns. As can be understood from FIG. 2, according to the present invention, a very high enrichment ratio (for example, 100 to 1) can be obtained from hydrogen gas containing hydrogen isotopes.
Deuterium can be concentrated and separated.

[0025]

According to the method and the apparatus of the present invention, the raw material gas can be successively passed through three or more storage towers filled with a storage agent for storing light hydrogen preferentially via valves. Thus, the hydrogen isotope (deuterium) can be concentrated in the leading storage tower, and this deuterium can be recovered as a high-purity product gas. The storage tower whose storage has been completed is
The stored raw material gas is desorbed by temperature control, exhausted to the outside of the system and regenerated, and can be used for new hydrogen isotope separation.After the concentrated hydrogen isotope gas is recovered as a product, By continuing the operation, the hydrogen isotope can be continuously concentrated and recovered. Further, the apparatus of the present invention only connects three or more storage towers filled with the storage agent, and the operation is only to open and close the valve and adjust and change the temperature of each storage tower. And running costs can be kept low, and hydrogen isotopes can be produced reliably with small-scale equipment.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing one embodiment of an apparatus of the present invention.

FIG. 2 shows the results of an experimental example in which natural hydrogen was concentrated according to the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 storage agent 2 first storage tower 3 second storage tower 4 third storage tower 5, 6, 7, 8 switching valve 9 source gas introduction path 10 source gas supply path 11 mass flow controller 12, 13, 14 switching valve 15 first Storage tower-second storage tower connection passage 16 Second storage tower-third storage tower connection passage 17 Third storage tower-first storage tower connection passage 18 Deuterium recovery path 19 Open / close valve 20 Needle valve 21 Mass flow controller 22 Condensation weight Hydrogen storage container 23 Pressure gauge 24 Exhaust gas recovery path 25 On-off valve 26 Needle valve 27 Mass flow controller 28 Exhaust gas storage container 29 On-off valve

Claims (8)

[Claims] 1. A method for concentrating and separating deuterium from a raw material gas in which deuterium is mixed with deuterium, comprising: n pieces (n ≧ n) filled with a storage agent that preferentially stores light hydrogen.
The storage towers of 3) are juxtaposed, and one storage tower is sequentially put on standby, and the remaining (n-1) storage towers are connected in series to form (n-
1) An occlusion step in which a raw material gas is supplied from a lower end of the last occlusion tower of the occlusion tower to occlude the gas in the occluding agent, and after the occlusion step is completed, the (n-1) occlusion is performed. The storage step at the end of the tower is disconnected from the connection, the temperature is raised, the light hydrogen-enriched gas is desorbed to regenerate the storage agent by desorbing the light hydrogen-enriched gas, and the recovery step is repeated. 1) A method for enriching and separating hydrogen isotopes, which comprises a recovery step of recovering concentrated deuterium from the upper end of the first storage tower of the book storage tower. 2. The method for concentrating and separating hydrogen isotopes according to claim 1, wherein 3 to 5 storage towers are juxtaposed. 3. The method for concentrating and separating hydrogen isotopes according to claim 1, wherein, in the step of regenerating the occluding agent, vacuum evacuation is further performed after desorbing the light hydrogen-enriched gas. 4. The method for concentrating and separating hydrogen isotopes according to claim 1, wherein palladium alumina pellets are used as the storage agent. 5. The method of claim 2, wherein in the regeneration step of the storage agent, the storage agent is
5. The method according to claim 4, wherein the temperature is raised to 00 ° C. 6. An apparatus for use in the method for enriching and separating hydrogen isotopes according to claim 1, wherein at least three occlusions are filled with an occluding agent for preferentially occluding light hydrogen and provided with a temperature adjusting means. Tower: a storage tower connection passage connecting the upper end of each storage tower to the lower end of the next storage tower; a raw material gas supply path and a raw material gas introduced from the raw material gas supply path and introduced into the lower end of each storage tower Path: an exhaust gas recovery path for discharging light hydrogen-enriched gas from the lower end of each storage tower to a storage container; a concentrated deuterium recovery path for extracting concentrated deuterium from the upper end of each storage tower and recovering the same in the storage vessel; A source gas flow path switching valve that is provided at a branch point between the supply path and the source gas introduction path and that is switched to guide the source gas to the source gas introduction path of any of the storage towers; Connect the lower end of each storage tower to the storage tower connection passage, A storage tower lower flow path switching valve that is switched so as to be connected to either the introduction path or the exhaust gas recovery path; disposed above each storage tower, the upper end of each storage tower is connected to the storage tower connection passage or the concentrated deuterium. A hydrogen isotope enrichment and separation device, comprising: a storage tower upper flow path switching valve that is switched to be connected to any one of the recovery paths. 7. The apparatus for concentrating and separating hydrogen isotopes according to claim 6, wherein a mass flow controller is provided in each of the concentrated deuterium recovery path, the exhaust gas recovery path, and the source gas supply path. 8. The apparatus for concentrating and separating hydrogen isotopes according to claim 5, wherein the exhaust gas recovery path is connected to a vacuum exhaust means.