JPS60239302A - Purification of single substance of hydrogen isotope - Google Patents

Abstract

PURPOSE:To prevent leakage of single substance of hydrogen isotope to the outside of a system and to elevate safety of environment by cracking carbon compds. and nitrogen compds. removed and recovered in a main system in a section other than the main system. CONSTITUTION:Gaseous single substance of hydrogen isotope is introduced into an oxygen removing stage 12 from an inlet 11, where the hydrogen isotope is allowed to react with oxygen at 100-200 deg.C in the presence of a catalyst to generate steam, which is removed in a dehumidifying stage 13. The residual gas is introduced into an impurity removing stage 14 where impurities such as carbon compds. or nitrogen compds. are removed by allowing the gas to contact with an adsorbent cooled to cryogenic temp., and the purified hydrogen isotope is discharged from an outlet 15. Impurities removed in the stage 14 are introduced into a cracking stage 16 where it is decomposed at 400- 500 deg.C in the presence of a catalyst, and the hydrogen isotope in the impurities are oxidized to form steam, which is fed to a moisture recovering stage 17 together with a part of the steam introduced from a stage 13 and recovered. Further, another part of the steam from the stage 13 is fed to a water decomposing stage 18, where it is decomposed and the single substance of the hydrogen isotope is fed back to the inlet 11, and the oxygen is circulated to the stage 16.

Description

Detailed Description of the Invention [Technical Field of the Invention] The present invention relates to hydrogen isotope gases (H, D
This invention relates to a method for purifying a simple hydrogen isotope for removing impurities from Lukaska whose main components are (Z, HT, DT, HD).

[Technical background of the invention and its problems] Unrefined hydrogen isotope gas contains impurities such as carbon compounds such as hydrocarbons, elemental compounds such as ammonia, and oxygen alone or oxides. There is. Among these impurities, it is ideal to decompose hydrogen isotope compounds and recover them as single hydrogen isotopes in the main components, especially deuterium, which has a small abundance in nature, and tritium, which is radioactive and dangerous. This becomes an unavoidable issue.

Among these hydrogen isotope compounds as impurities, nitrogen compounds and carbon compounds are difficult to decompose directly into hydrogen isotopes, so they are first oxidized and converted to water vapor, and then decomposed to form hydrogen isotopes. The method is to obtain a single body.

That is, when a hydrogen isotope is expressed as H', it is expressed by the following two-step formula.

(1) 4NHB' + 702 →4NO2+ 6H
2'0CH4' + 204-> CO2, + 2H2
'0(II) 2H2'O→ 2H2'+02Here,
The carbon and nitrogen hydrides are CH4' and NH
It is represented by 8'.

According to this method, the purification system shown in FIG. 1 has been considered. In other words, the gas to be treated has a system population of 1
Hydrogen isotope compounds such as hydrocarbons and ammonia are cracked in the high-temperature catalyst tower 2, and the above (1)
Each of these hydrogen isotope compounds is converted into an oxide by the reaction. Next, it enters the low-temperature catalyst tower 3, where the impurity elemental oxygen reacts with hydrogen isotopes to generate water vapor.

The water vapor produced here and the water vapor coming from upstream are removed in the next dehumidifier 4, and carbon dioxide and nitrogen dioxide produced in the high temperature catalyst tower 2 are removed in the next low temperature adsorption tower 5. The high purity gas from which impurities have been removed as described above is sent out from the system outlet 6.

On the other hand, the moisture recovered by the dehumidifier 4 is decomposed into hydrogen isotope and oxygen in the water decomposition device 7, and the former is returned to the system population 1 through the hydrogen isotope recovery route 8, and the latter is is collected through the simple oxygen route 9 in the low-temperature adsorption tower 5.
It is discharged to the outside of the yarn along with carbon dioxide and nitrogen dioxide through the exhaust route IO.

However, in the above purification system, the high temperature catalyst tower 2 is
Since it is operated at a high temperature of about 00 to 500°C, there is a risk that hydrogen isotope, which is the main component in the gas to be treated, may leak through the metal wall. Hydrogen isotopes alone are flammable, so if they leak outside the system, there is a possibility of an explosion if proper treatment is not taken, and among isotopes, tritium is radioactive and therefore dangerous. Furthermore, since these are elements with a small natural abundance ratio, this is also a loss.

[Object of the invention] The present invention has been made to solve the above problems,
It is an object of the present invention to provide a method for refining a single hydrogen isotope that suppresses the risk of hydrogen isotope leaking out of the system and increases safety. This method involves the purification of hydrogen isotopes containing nitrogen compounds such as oxygen, oxides, etc. as impurities, including the process of removing oxygen, the process of removing moisture, and the remaining impurities consisting of carbon compounds, nitrogen compounds, etc. The risk of leakage of individual hydrogen isotopes to the outside of the system is reduced by sequentially performing the process of removing hydrogen isotopes in the main system of the refining system, and performing the cracking process of the carbon compounds and nitrogen compounds removed and recovered in the main system outside the main system. It is characterized by improved safety by suppressing

Moisture removed in the main system in the purification method of the present invention,
The hydrogen isotope generated through further decomposition can be returned to the main system to reduce its loss.

In addition, in the cranking step, hydrogen isotopes are recovered as oxides, which are further decomposed to generate hydrogen isotope compounds, thereby reducing the loss of the hydrogen isotopes.

In the purification method of the present invention, the step of removing oxygen is preferably carried out by a method of reacting oxygen with a hydrogen isotope gas as a main component at 100 to 200°C in the presence of a catalyst to generate water vapor. The step of removing the components is preferably carried out by a low-temperature condensation method or an adsorption method using a desalting agent. Furthermore, the process of removing impurities such as carbon compounds and nitrogen compounds is
A method of adsorption and removal using an adsorbent that has withstood extremely low temperatures is suitable.

[Embodiments of the invention] An embodiment of the present invention will be described with reference to FIG.

The gas to be treated is introduced from the system population 1j, and the oxygen removal step 12. It is processed in the order of dehumidification step 13 and impurity removal step 14, and then sent out from the system outlet 15.

The impurities recovered in the impurity removal step 14 pass through a cracking step 16, a moisture recovery step 17, and are discharged to the outside of the system from an exhaust outlet 19. The water recovered in the dehumidification process 13 and the moisture recovery process 17 passes through a water decomposition process 18, where the hydrogen isotope is returned to the system population 11 and the oxygen is returned to the cracking process 16.

The above is an overview of the processing steps, and each step will be explained next. As described above, the gas to be treated is hydrogen isotope gas containing impurities such as carbon compounds such as hydrocarbons, nitrogen compounds such as ammonia, and oxygen and oxides.
Water vapor is generated by combining oxygen, which is an impurity, with hydrogen isotope, which is the main component, under a catalyst at an operating temperature of 0 to 200°C. Next, in a dehumidifying step 13, moisture in the gas is removed by a cold trap condensation method using a low-temperature refrigerant or an adsorption method using an adsorbent or a hygroscopic frame. The turbidity-treated gas undergoes impurity removal step 1.
4, remaining impurities such as hydrocarbons and ammonia are removed. In this step, for example, a low-temperature adsorption tower cooled to about the temperature of liquid nitrogen is used. The gas purified through the above three steps exits from the system through the system outlet 15 as a high-purity hydrogen isotope simple gas.

The treatment methods exemplified in the dehumidification step 13 and the impurity removal step 14 above are all methods of accumulating the removed impurities in the equipment, so it is necessary to replace the equipment when the accumulated amount is saturated. Install more than one device, operate only one, and when it reaches saturation, replace it with another one, regenerating the saturated device. Examples of regeneration methods include heating, purging with an inert gas, and evacuation.

The impurities obtained by such regeneration treatment from the impurity removal step 14 are transferred to a cracking step 16, where hydrocarbons and ammonia are cracked under a catalyst at an operating temperature of, for example, 400 to 500°C. , hydrogen isotopes contained in each are oxidized to produce water vapor. The water vapor generated here is recovered in a moisture recovery step 17, and the remaining water vapor is
It is discharged from 9. This moisture recovery step 17 is the dehumidification step 1.
It is performed by the same method as 3, and is reproduced in the same way.

The water recovered and regenerated from the dehumidification process 13 and the moisture recovery process 17 is liquefied, and in the water decomposition process (8),
For example, it is decomposed by electrolysis into hydrogen isotopes and oxygen. The former is returned to the system population 13, and the latter is returned to the cracking process 16.0 By processing as described above, the cracking process, which requires high operating temperatures, can be removed from the main system. Since cracking does not occur when the hydrogen isotope is close to 100 cm, the risk of hydrogen isotope gas leaking from the pipe wall can be extremely reduced. Since hydrogen isotope compounds are recovered in the form of fixed substances such as adsorbents, even if the system were to fail, it would take time for the system to diffuse, giving more time for countermeasures and ensuring safety. You can make it higher.

[Effects of the Invention] By removing the cracking process from the main system of the refining system, the present invention can reduce leakage of hydrogen isotopes from the pipe wall, and provide a highly safe refining method. .

In addition, according to the purification method 1 of the present invention, hydrogen isotopes can be almost completely recovered, so the risk of radioactive gases such as triplex water being released into the general environment can be avoided, and the natural abundance ratio can be avoided. The loss of small elements can be prevented.

Furthermore, by removing the high-temperature cracking process from the main system, the high-temperature equipment can be managed independently, which has the advantage of simplifying equipment.

[Brief explanation of the drawing]

Fig. 1 is a process diagram showing a conventional n-back method for producing a single hydrogen isotope, and Fig. 2 is a process diagram showing an embodiment of the present invention. 4... Dehumidifier 5... Low temperature adsorption tower 7... Water decomposition device IO... Exhaust outlet 12... Oxygen removal process 13... Dehumidification process 14... Impurity removal process 16...・Cracking process 17...Moisture recovery process 18...Water decomposition process 19...Exhaust outlet agent Patent attorney Akira Ino-Yoshi (1 person) 1st
figure

Claims (1)

[Scope of Claims] (1) A step of removing oxygen, a step of removing moisture, and a step of removing remaining impurities such as carbon compounds and nitrogen compounds are performed in sequence in the main system of the 18M system, and the main system 1. A method for purifying a single hydrogen isotope, characterized in that a cranking step of carbon compounds and nitrogen compounds removed and recovered in the step is performed in a system other than the main system. (2) The refining method according to claim 1, in which the moisture removed and recovered in the main system of the refining system is decomposed and the generated hydrogen isotope is returned to the main system. (81 Cracking process for carbon compounds and nitrogen compounds (2) Hydrogen isotopes are recovered as oxides, which are further decomposed, and the generated hydrogen isotopes are returned to the main system as described in claim 1. (4) The step of removing oxygen is carried out at 100°C in the presence of a catalyst.
Claim 1g1, which is achieved by reacting oxygen and hydrogen isotope simple gas at 200°C to vaporize it.
Purification method described in section. (6) The purification method according to claim 1, wherein the step of removing moisture is carried out by a low temperature condensation method or fc is carried out by an adsorption method using a dehumidifying agent. (6) The purification method according to claim 1, wherein the step of removing remaining impurities such as carbon compounds and nitrogen compounds is carried out by adsorption and removal using an adsorbent cooled to an extremely low temperature.