JPS6116503B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for purifying inert gases such as helium gas and argon gas, and specifically relates to a method for purifying inert gases such as helium gas used in high-temperature gas reactors, argon gas used in fast breeder reactors, and inert gases used in semiconductor manufacturing. This relates to a purification method that removes impurities such as oxygen and hydrogen from the inside. If hydrogen gas or oxygen gas is present in the helium gas used in a high-temperature gas reactor, it will react with the graphite that forms the core structure of the reactor, producing hydrocarbons and carbon dioxide gas, causing significant wear and tear on the graphite. Shorten the life of the nuclear reactor. Furthermore, the presence of oxygen gas in the argon gas used in fast breeder reactors causes loss of sodium and shortens the life of the reactor. Additionally, the presence of oxygen in the nitrogen gas used in semiconductor manufacturing produces unnecessary oxides.
Unfavorable problems arise in semiconductor manufacturing. Therefore, it is necessary to remove these impurities from an inert gas such as helium gas or argon gas. In order to meet this need, the present inventor first developed a
On November 29, 1970, he invented a "removal agent for oxygen or hydrogen in gas" and filed a patent application as Japanese Patent Application No. 141824-1972. The application was filed as Application No. 52-62231. However, in the process of reactivating these copper-based reactants by oxidizing and reducing them, if you suddenly try to reactivate them with a high concentration of oxygen or hydrogen, the reactants will react violently and the temperature will rise due to their own reaction heat. If the temperature rises abnormally, accidents such as melting of the reactant itself may occur, so use a mixed gas in which oxygen or hydrogen, which is a regeneration gas, is added to an inert gas as a diluent. It is necessary to carry out reactivation while controlling the reactivation process so that the inert gas used as a diluent in such a reactivation method is not consumed in the reaction, but is simply added as a regeneration gas such as oxygen or Since only hydrogen was consumed in the reaction, a reactivation method was created in which the inert gas was recycled and reused, and was filed as Japanese Patent Application No. 1985-85106. However, in conventional purification using copper-based reactants, when reactivating a copper-based reactant that has lost its reaction ability, oxygen or hydrogen is mainly diluted with an inert gas such as nitrogen gas, and the copper-based reactant is Reactivation has been carried out by bringing it into contact with a reactant and performing oxidation or reduction, but in order to restart production, it was necessary to completely remove the nitrogen gas from the reactivation system. In the conventional method, therefore, a step of purging the gas is required, and the economic loss of nitrogen gas and operational loss associated with this cannot be avoided. The inventor of the present invention considered eliminating such economic loss, work process, and work time loss. In order to reactivate the copper-based reactant, the same gas as the produced gas is used as a diluent, and after the reactivation is completed, the regeneration gas remaining in the regeneration system is further reacted with the copper-based reactant, resulting in regeneration. By eliminating residual gas,
The present invention was created based on the idea that there is no need to purge the mixed gas of dilution gas and regeneration gas after reactivation, and purification can be restarted immediately at that point. That is, in a method for purifying an inert gas such as helium gas or argon gas using a copper-based reactant, the present invention reactivates the copper-based reactant in the first step by converting the gas to be purified into a purified gas for regeneration. Gas is added to dilute the regeneration gas, which is then circulated for reactivation. In the second stage, the addition of regeneration gas is stopped and the temperature of the copper-based reactant is raised to produce only purified gas. Provided is a method for purifying gas such as helium gas using a copper-based reactant, characterized in that the regeneration gas remaining in the circulating system is further reacted with a copper-based reactant to be removed, and then purification is restarted. It is something to do. Hereinafter, the present invention will be explained in detail based on the drawings. In FIG. 2 showing an embodiment of the apparatus used in the purification method of the present invention, a refining cylinder 2 is filled with a copper-based reactant 1 containing CuO or Cu as a main component, and a heater 3 is placed in the upper part of the cylinder. It has a built-in structure, and multiple purification cylinders can be installed as needed. Although the heater 3 is built in the upper part of the refining cylinder in the illustrated example, it is also possible to install it outside the cylinder and introduce heating gas into the cylinder. A gas supply pipe 4 for injecting the gas to be purified into the cylinder is connected to the cylinder head of the purification cylinder 2, and a gas discharge pipe 5 for discharging the purified gas is connected to the cylinder bottom. has been done. In addition, copper-based reactant 1
A gas circulation pipe 8 for feeding diluted regeneration gas for reactivation is connected to connect the cylinder head and cylinder bottom. Further, the gas discharge pipe 5 and the gas circulation pipe 8 are connected by a purified gas introduction pipe 7. The above-mentioned pipes are provided with valves a, valve b, valve c, valve d, and valve e, respectively, as shown in the figure. A regeneration gas cylinder 9 is connected to the gas circulation pipe 8 via a regeneration gas injection pipe 12, and the pipe 12 is provided with a valve f. Also,
The gas circulation pipe 8 includes a circulation pump 6 and a cooler 1.
3. Equipment necessary for gas circulation such as a drain separator 14 is installed. To perform purification using the above apparatus, an inert gas such as helium gas or argon gas is fed into the cylinder 2 through the gas feed pipe 4. When hydrogen gas is mixed as an impurity in the gas to be purified, the cylinder is filled with copper-based reactant 1 containing CuO as the main component, and when oxygen gas is mixed as an impurity, Cu A copper-based reactant 1 containing as a main component is charged into a cylinder and purified. As the copper-based reactant 1, the remover described in Japanese Patent Application No. 1983-62231, which is the invention of the present inventor, is used, that is, copper oxide or copper powder is molded using a binder, or On the surface of a product sintered without using a binder,
It is preferable to use a removal agent to which palladium is attached. Impurities in the gas to be purified that is sent into the purification cylinder 2 are removed at a predetermined internal temperature, for example around 200 to 220℃, and when removing oxygen gas, 2Cu + O ₂ → 2CuO hydrogen gas is removed. In the case of CuO+H ₂ →Cu+H ₂ O, it reacts with each copper-based reactant 1 and is removed from the gas to be purified. That is, purified inert gas such as helium gas or argon gas is discharged from the gas discharge pipe 5. Note that when hydrogen gas is removed, water is also discharged together as shown in the above chemical formula. However, such a reaction also has a reaction limit, and when a certain amount of impurities is removed, the copper-based reactant 1 no longer reacts. At this stage, the valve a is closed to stop the supply of the gas to be purified into the cylinder 2 through the gas supply pipe 4, the purification is stopped, and the copper-based reactant 1 is reactivated. To reactivate the copper-based reactant 1, in the first step, valve e is opened to introduce purified gas from the purified gas introduction pipe 7 into the gas circulation pipe 8, and this purified gas is activated by the circulation pump 6. The gas circulation pipe 8 and the refining cylinder 2 are circulated by the cylinder 2.
The internal temperature is raised to a predetermined temperature of, for example, around 200 to 220°C by the heater 3 and circulated. When the cylinder temperature reaches a predetermined temperature, regeneration gas is mixed into the circulating gas. That is, by opening the valve f, an appropriate amount of regeneration gas is supplied from the regeneration gas cylinder 9 to the flowmeter 1.
While metering at zero, the purified gas is introduced into the gas circulation pipe 8. That is, when it is necessary to reduce the copper-based reactant, hydrogen gas is added to the purified gas as a regeneration gas, and when it is necessary to oxidize the copper-based reactant, oxygen gas is added to the purified gas as the regeneration gas. The purified gas serves as a dilution gas for the regeneration gas and continues to be safely circulated. The regeneration gas added to the purified gas reacts with the copper-based reactant 1 at a predetermined temperature in the purification cylinder 2 to be oxidized or reduced, and reactivation progresses. Such a redox reaction also has a limit, and the reaction eventually stops. That is, the reaction at the predetermined temperature is completed. However, approximately 1% of the regeneration gas remains in the circulating gas. As long as even a trace amount of regeneration gas remains in the circulating gas, it is not possible to switch to the purification process, so it is necessary to remove the regeneration gas from the circulating gas. Therefore, in the second stage, the temperature inside the cylinder 2 is further increased by 20 to 60°C by the heater 3, and the valve f is closed to stop the supply of the regeneration gas. Under such elevated temperature, the reaction between the copper-based reactant 1 and the regeneration gas occurs again, so after a while,
The regeneration gas in the circulating gas is completely removed, that is, only the purified gas is circulating in the gas circulation pipe 8 and the purification cylinder 2. When such a situation occurs, the process is switched to the purification process. That is, valve c, valve d, and valve e are closed to stop the reactivation process, valve a and valve b are opened, and the gas to be purified is fed into the purification cylinder 2 through the gas feed pipe, and the purification is restarted. do. Purification is thus restarted, and purified inert gas such as helium gas or argon gas is discharged from the gas discharge pipe 5. The purification continues in this manner, but if the copper-based reactant 1 becomes in a state that requires reactivation again, the process is switched to the above-mentioned reactivation step. If two or more purification cylinders 2 are installed together and the purification and reactivation are alternately operated, purification can be performed continuously. Figure 1 shows a system diagram of an apparatus in which two refining cylinders are installed together. In addition, if there is only one refining pipe 2, refining is stopped during reactivation, and the gas discharge pipe 5
It is possible to supply purified gas as a dilution gas from a buffer tank (not shown) located downstream of the purification gas, or to supply the same gas as the purified gas from a separate cylinder. The present invention utilizes a known technique in which a copper-based reactant that has stopped reacting with the regeneration gas at a certain temperature starts reacting again at an even higher temperature during the in-cylinder reactivation process. This is applied to remove the regeneration gas remaining in the circulating gas, and at the end of the reactivation process, the circulating gas can be changed to only inert gas and the process can be directly switched to the purification process. Therefore, if the same inert gas as the gas to be purified is used as the diluent in the reactivation step, there is no need to discard it even after the reactivation is completed. According to the method of the present invention, an inert gas such as helium gas or argon gas mixed with impurities such as oxygen gas or hydrogen gas can be purified to a high degree of purity.
Furthermore, purified gas can be used as the diluent gas for reactivating the copper-based reactant, and it can be reused without being discarded even after reactivation, which is economically advantageous. It is a superior gas purification method compared to conventional methods, as there is no work involved or the dangers associated with it, and the work is highly safe. Example 1 Helium gas mixed with hydrogen gas was purified using the apparatus shown in the system diagram shown in FIG. The specifications and operating conditions of each part of the equipment used are as follows. Purification cylinder 2-1, 2-2 Inner diameter 297.9mm Cross-sectional area 697.0cm ² Reactant packed bed Height 400mm Volume 27.88 Weight 22.3Kg Copper-based reactant 1-1, 1-2 In the specification of Japanese Patent Application No. 1982-62231 Therefore, 9 parts by weight of copper oxide powder and 1 part by weight of clay were mixed into a diameter of approximately
Formed into pellets of 1.6mm and approximately 4mm in length, loaded with palladium and fired at 400℃. Heater 3-1, 3-2 U-shaped sheathed heaters (maximum 53KW) were attached to the head of the refining cylinder. Regeneration gas filling cylinder 9 Oxygen cylinder pipes for 7000 4, 5, 7, 8 Stainless steel pipes with a diameter of 1 inch were connected. Gas flow control valve 11 A flow control valve with a diameter of 3/8 inch manufactured by Yamatake Honeywell was used. Operating conditions (1) Purification process (during operation to remove hydrogen gas from helium gas) Fluid Helium gas Pressure 40Kg/cm ² G Flow rate 806.4Nm ² /Hr Hydrogen addition amount 200N/Hr Operating temperature 260℃ (2) Regeneration process (During operation when helium is introduced from the outlet on the refining side and mixed with oxygen gas to reactivate the copper-based reactant) Fluid Helium gas Pressure 40Kg/cm ² G Flow rate 40Nm ³ /Hr Oxygen concentration 0.1 to 1.0% Operating temperature 1st stage 220°C 2nd stage 240°C Helium gas mixed with hydrogen from the reactor simulator is initially passed through the injection pipe 4 to 1 of the first purification cylinder 2, and the valves A ₁ and B ₁ are open (valve a ₂ , valve b ₂ , valve c ₁ , valve c ₂ , valve
d ₁ and valve d ₂ were closed), and hydrogen was removed from the helium gas under the operating conditions of the purification step (1) above. The helium gas was purified, and highly purified helium gas and water were discharged from the discharge pipe 5. After continuous operation for about 4 hours, the reaction capacity of copper-based reactant 1 reached its limit, so valves A ₂ and B ₂
The helium gas to be purified is sent to 2 of the second purification cylinder 2 by opening, and the purification by 1 of the first purification cylinder 2 is stopped by closing the valve a ₁ and valve b ₁ . Purification was continued in step 2 of 2. Next, open valve _c1 and valve _a1 , and open valve e.
is opened, the circulation pump 6 is activated, and purified helium gas is introduced into the pipe 8 through the pipe 7.
Purified helium gas was introduced into the first purification cylinder 2 through the pipe 8 . That is, the circulation pump 6 was operated to circulate the inside of the refining cylinder 2 and the inside of the pipe 8. The temperature inside 1 of purification cylinder 2 is controlled by 1 of heater 3.
The temperature was raised to 220°C, and from the time the temperature rose to 220°C, the valve e was closed and the addition of oxygen from the oxygen cylinder 9 to the helium gas circulating through the pipe 8 was started. Oxygen concentration was adjusted within the range of 0.1% to 1%. By continuing to circulate the oxygen gas diluted with helium gas in this way, the reactivation of the reactant 1 in the refining column 2 was completed. During this time, 400% of oxygen was mixed into the helium gas. In this way, copper-based reactant 1 1 could be reactivated, but when the oxygen concentration inside purification column 2 1 was analyzed, about 1% oxygen was detected. Here, close the valve f to stop the supply of oxygen, and while continuing to circulate only the purified gas, use the heater 3 to raise the temperature inside the cylinder 1 of the purification cylinder 2 from 220°C to 240°C.
The temperature was raised to 0.degree. C., and residual oxygen in the purification cylinder and pipe 8 was further reacted with copper-based reactant 1.
The remaining oxygen concentration was reduced to 0.4 ppm in about 15 minutes. Therefore, valve c ₁ and valve d ₁ were closed to stop reactivation. Next, purification in 2 of the second purification column 2 was switched to 1 in the first purification column 2. That is, open valve a ₁ , close valve a ₂ (valve c ₁ and valve c ₂ are closed), and open valve b ₁
Open the valve b ₂ and close the valve b 2 (valve d ₁ and valve d ₂ are closed) to send helium gas through the pipe 4 to the 1 of the first purification cylinder 2 and purify it in the 1 of the first purification cylinder 2. Then, in parallel with this, reactivation of reactant 1-2 in second purification column 2-2 was carried out in the same manner as the reactivation method described above. That is, the valves c ₂ and d ₂ were opened, and helium gas mixed with oxygen was fed into the refining column 2 through the pipe 8, and this was circulated and reactivated. That is, by installing two purification columns 1 and 2 in parallel, while one purification column is performing purification, the other purification column is reactivating the copper-based reactant. I did it. That is, the purification was carried out alternately, during which the reactivation of the copper-based reactant was carried out in parallel, but this was done safely and the purified helium gas discharged from the pipe 5 at the time of switching every 4 hours. Inside, no oxygen concentration was detected above 0.4 ppm. Example 2 Argon gas mixed with oxygen was purified using the system diagram shown in FIG. The specifications and operating conditions of each part of the equipment used are as follows. Purification cylinder 2 Inner diameter 150mm Cross-sectional area 176.7cm ² Reactant packed bed Height 400mm Volume 7.1 Weight 5.7Kg Copper-based reactant 1 The same copper-based reactant used in Example 1 was treated with hydrogen reduction. Heater 3 A U-shaped sheathed heater (maximum 1.5KW) was installed inside the refining cylinder head. Regeneration gas hydrogen cylinder 9 7000 Hydrogen cylinder pipes 4, 5, 7 and 8 Stainless steel pipes with a diameter of 1/2 inch were connected. Gas flow rate control valve 11 One manual needle valve manufactured by Fuji Metals was used. Operating conditions (a) Purification process (purification to remove oxygen from argon gas) Fluid Argon gas Pressure 2Kg/cm ² G Flow rate 10Nm ³ /Hr Oxygen addition amount 29N/Hr Operating temperature 200℃ (B) Regeneration process (purification Purified argon gas is introduced from the bottom outlet of the cylinder, hydrogen gas is added and mixed,
During activation when the copper-based reactant was reactivated) Fluid: Argon gas Pressure: 2 Kg/cm ² G Flow rate: 10 Nm ³ /Hr Hydrogen concentration: 0.1 to 1% Hydrogen 465 was mixed into argon gas. Operating temperature 220°C in the first stage 260°C in the second stage Argon gas mixed with oxygen is initially passed through the injection pipe 4 to the purification cylinder 2 filled with the copper-based reactant 1.
The oxygen in the argon gas was removed under the operating conditions of the purification step (a) above. Highly purified purified argon gas was discharged from the discharge pipe 5. Approximately 8
After continuous operation for hours, the reaction capacity of copper-based reactant 1 reached its limit, so purification was stopped. That is,
Valve a was closed to stop the supply of argon gas to be purified from pipe 4, and valve b was closed to stop purification. Next, valves c and d are opened, circulation pump 6 is operated, valve e is opened, and purified argon gas is introduced from a buffer tank (not shown) into pipe 8 through pipe 7, and the purified argon gas is introduced into pipe 8 from the buffer tank (not shown). 8 was circulated. The internal temperature of the refining cylinder is set to 220°C using the heater 3, and from this point on, the valve f is opened to allow hydrogen gas to flow from the hydrogen cylinder 9 into the pipe 8 through the pipe 12 while being measured using the flow meter 10 and being adjusted using the flow control valve 11. Added. That is, hydrogen gas diluted with argon gas was fed and circulated into the refining column 2 to reactivate the copper-based reactant 1. That is, the copper-based reactant was reactivated under the operating conditions of the regeneration step (b) above. During that time, 465 hydrogen gas was added. When gas circulation was continued for about 8 hours, the reaction between the copper-based reactant 1 and the hydrogen gas for regeneration was completed, and no further reaction was observed. Hydrogen concentration in the gas was detected at 1%. Therefore, valve f was closed to stop the addition of hydrogen gas, and valve e was also closed. By the heater 3,
The internal temperature of the refining cylinder 2 was raised from 220°C to 260°C, argon gas was continued to be circulated, and hydrogen gas remaining in the gas was further reacted with the copper-based reactant 1 to be removed. Summer. When argon gas was continued to be circulated for about 10 minutes, any hydrogen gas remaining in the circulating gas was completely removed, and the hydrogen concentration in the gas became 0.4 ppm or less. That is, copper-based reactant 1
was reduced and reactivated. Therefore, valves c and d were closed to stop the circulation of argon gas for reactivation. Next, valve a and valve b are opened, and the argon gas to be purified is sent into the purification cylinder 2.
Refining was restarted under the operating conditions of the refining step (a) above. Highly purified argon gas with an oxygen concentration of 0.4 ppm or less was discharged from pipe 5, allowing the intended purification to continue. It was possible to repeat the purification process and the reactivation process and perform switching operations.

[Brief explanation of the drawing]

FIG. 1 is a system diagram of an apparatus having two refining cylinders installed side by side as one embodiment of the present invention.
FIG. 2 is a system diagram of an apparatus having one refining column as another embodiment of the present invention. The correspondence between the main parts illustrated and the symbols is as follows. 1... Copper-based reactant, 2... Purification column, 3... Heater, 4
...Gas feed pipe, 5...Gas discharge pipe, 6...Circulation pump, 7...Gas introduction pipe, 8...Gas circulation pipe, 9...Regeneration gas cylinder, 10...Flow meter, 1
1...Flow control valve, 12...Gas injection pipe, 113
...Cooler, 14...Drain separator, 15...Thermometer, a, b, c, d, e, f...Valve.

Claims (1)

[Claims] 1 In the purification method using a copper-based reactant for an inert gas such as helium gas or argon gas, the copper-based reactant is reactivated in the first step by adding regeneration gas to the purified gas. The regeneration gas is diluted and reactivated by circulation. In the second stage, the addition of the regeneration gas is stopped and the temperature of the copper-based reactant is raised, and only the purified gas is circulated to complete the circulation system. A method for purifying gases such as helium gas using a copper-based reactant, characterized in that the regeneration gas remaining in the gas is further reacted with a copper-based reactant to be removed, and then the purification is restarted.