TWI545081B - Purifying method and purifying apparatus for argon gas - Google Patents

Description

Argon purification method and purification device

The present invention relates to a method and apparatus for purifying argon containing at least oxygen, hydrogen, carbon monoxide, hydrocarbons, oil and nitrogen as impurities.

For example, in a bismuth single crystal pulling furnace, a ceramic sintering furnace, a vacuum degassing apparatus for steelmaking, a tantalum plasma dissolution apparatus for a solar cell, and a polycrystalline tantalum casting furnace, argon gas is used as an ambient gas in a furnace or the like. The argon gas recovered from the above-mentioned equipment for reuse is reduced in purity due to the incorporation of hydrogen, carbon monoxide, air, or the like. Therefore, in order to increase the purity of the recovered argon gas, the impurities to be mixed are adsorbed to the adsorbent. Furthermore, it is proposed that the adsorption of the impurities is performed efficiently, and the oxygen in the impurities is reacted with the combustible component to be converted into carbon dioxide and water as a pretreatment for the adsorption treatment (see Patent Documents 1 and 2).

In the method disclosed in Patent Document 1, first, the amount of oxygen in the argon gas is adjusted so as to become slightly smaller than the stoichiometric amount required for completely combusting a combustible component such as hydrogen or carbon monoxide. Then, palladium or gold which reacts hydrogen with oxygen in preference to carbon monoxide and oxygen is used as a catalyst to react oxygen in argon with carbon monoxide, hydrogen, etc., thereby generating carbon dioxide in a state in which only carbon monoxide remains. with water. Then, carbon dioxide and water contained in the argon gas are adsorbed to the adsorbent at normal temperature, and then one of the carbon oxides and nitrogen contained in the argon gas are adsorbed to the adsorbent at a temperature of -10 ° C to -50 ° C.

In the method disclosed in Patent Document 2, the amount of oxygen in the argon gas is made an amount sufficient to completely burn the combustible components such as hydrogen and carbon monoxide, and then The oxygen in the argon gas is reacted with carbon monoxide, hydrogen, or the like using a palladium-based catalyst to generate carbon dioxide and water in a state in which oxygen remains. Then, the carbon dioxide and water contained in the argon gas are adsorbed to the adsorbent at normal temperature, and then the oxygen and nitrogen contained in the argon gas are adsorbed to the adsorbent at a temperature of about -170 °C.

In the method disclosed in Patent Document 3, when the argon gas discharged from the single crystal manufacturing furnace or the like contains oil, the oil is removed by using a degreasing cylinder containing activated carbon or the like and a degreasing filter. Then, the oxygen in the argon gas introduced into the catalyst cylinder is reacted with the added hydrogen to be converted into water. Then, the water introduced into the argon gas in the adsorption column is adsorbed and removed by carbon dioxide, and then purified by a rectification operation.

In the method disclosed in Patent Document 4, in order to purify argon gas containing carbon monoxide, hydrogen, oxygen, and nitrogen as impurities, one carbon oxide and hydrogen in argon gas are reacted with oxygen, thereby residual carbon monoxide. Carbon dioxide and water are produced in the state. Then, carbon dioxide, water, nitrogen and carbon monoxide in the argon gas are adsorbed to the adsorbent at 10 to 50 ° C, and the adsorbent is regenerated at 150 to 400 ° C. Further, in order to adsorb nitrogen in argon gas, a copper ion exchange ZSM-5 type zeolite (copper ion exchange rate: 121%) was used as an adsorbent.

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent No. 3496079

[Patent Document 2] Japanese Patent No. 3737900

[Patent Document 3] Japanese Patent Laid-Open Publication No. 2000-88455

[Patent Document 4] Japanese Patent Laid-Open Publication No. 2006-111506

In the method described in Patent Document 1, in the first-stage reaction of the pretreatment, carbon dioxide and water are generated in a state in which carbon monoxide remains in the argon gas. However, in the case where there are many hydrocarbons contained in the argon gas, it is necessary to raise the reaction temperature, so that carbon monoxide also reacts with oxygen, so that it is difficult to leave carbon monoxide. Therefore, since hydrogen cannot be adsorbed and removed in the subsequent adsorption treatment at normal temperature, there is a problem that hydrogen remains in the argon gas and the argon gas cannot be purified with high purity.

In the method described in Patent Document 2, the amount of oxygen contained as an impurity in the argon gas is an amount sufficient to completely burn hydrogen, carbon monoxide or the like in the pretreatment stage, whereby the residual oxygen is present. Produces carbon dioxide and water. However, it is necessary to lower the temperature at the time of adsorption to about -170 ° C when adsorbing the above residual oxygen. That is, since oxygen remains in the pretreatment stage of the adsorption treatment, there is a problem that the cooling energy at the time of adsorption treatment increases and the purification load becomes large.

In the method described in Patent Document 3, the oil contained in the argon gas is removed by adsorbing it to the activated carbon. However, when argon gas is recovered, for example, in the case of using a machine such as an oil-rotating vacuum pump to maintain airtightness or the like, the oil is thermally decomposed to generate a hydrocarbon component. Even if there is a mist separator for oil removal, the above hydrocarbon component passes through the oil mist separator. Thus, the hydrocarbon derived from the oil contained in the argon gas becomes very large, the methane is a tens of ppm or more, and the hydrocarbon having a carbon number of 2 to 6 (C2 to C6) is a hydrocarbon having a carbon number of 1. The (C1) conversion is calculated to be several hundred ppm or more. Methane, which is not adsorbed on activated carbon and has a carbon number of 2 to 6, is hardly adsorbed to the activated carbon and passes through the catalyst cylinder, so that there is a disadvantage that the subsequent distillation load is increased.

Patent Document 4 does not disclose any oil component contained in argon gas or hydrocarbons generated as a by-product due to decomposition of oil.

It is an object of the present invention to provide a method and a purification apparatus for purifying argon which can solve the problems of the prior art as described above.

The method of the present invention is characterized in that it is a method for purifying argon gas containing at least oxygen, hydrogen, carbon monoxide, hydrocarbons, oil and nitrogen as impurities, so that one part of the hydrocarbon in the argon gas and the oil are adsorbed to the activated carbon; And determining whether the amount of oxygen in the argon gas exceeds a predetermined amount required to react with all of the hydrogen, carbon monoxide, and hydrocarbons in the argon gas, and when the amount of oxygen in the argon gas is less than the set amount, Oxygen is added in such a manner that the amount is more than the above-mentioned amount; and then, ruthenium is used as the first reaction catalyst, and one of the argon gas, carbon, hydrogen, and hydrocarbon is reacted with oxygen to generate carbon dioxide in a state in which oxygen remains. Water; then, carbon monoxide is added in such a manner that one of the argon gases exceeds the amount required to react with all of the residual oxygen; and then a mixture of ruthenium, osmium, or the like is used as the second reaction catalyst. And reacting oxygen in the argon gas with carbon monoxide to generate carbon dioxide in a state in which carbon monoxide remains; and then, by pressure swing adsorption method Said argon of at least carbon monoxide, carbon dioxide, water, and nitrogen adsorbed on the adsorbent.

According to the present invention, the oil contained in the argon gas is adsorbed by the activated carbon, thereby The activated carbon also adsorbs a part of the hydrocarbon derived from the oil, and in particular, the hydrocarbon having a carbon number of 1 to 6 can be efficiently adsorbed by the activated carbon. Thereby, the amount of hydrocarbons in the argon gas is reduced, so that the amount of water and carbon dioxide generated by the reaction of hydrocarbons and oxygen in the subsequent step can be reduced, and the subsequent adsorption load can be alleviated.

Further, hydrazine is used as the first reaction catalyst to cause hydrogen, carbon monoxide, and hydrocarbons in the argon gas to react with oxygen, whereby carbon dioxide and water are generated in a state in which excess oxygen remains. The ruthenium used as the first reaction catalyst has good heat resistance and high reactivity. Therefore, when argon gas contains a large amount of a lower hydrocarbon such as methane, the reaction temperature can be raised to sufficiently carry out the reaction, and the reaction is effectively carried out. Reduce hydrocarbons in argon.

The residual oxygen is reacted with the newly added carbon monoxide by using a mixture of ruthenium, osmium, or the like as the second reaction catalyst, and carbon dioxide is generated in a state in which carbon monoxide remains. Thereby, the oxygen in the argon gas is removed. By using ruthenium, osmium, or a mixture of these as the second reaction catalyst, the reaction between water and carbon monoxide can be suppressed to suppress hydrogen generation. Thereby, in the stage of pretreatment by the adsorption treatment by the pressure swing adsorption method, it is possible to prevent hydrogen which is hard to be removed in the adsorption treatment from remaining in the argon gas, so that the argon gas can be purified with high purity. Further, in the stage of pretreatment by the adsorption treatment by the pressure swing adsorption method, oxygen can be removed from the argon gas, so that the purification load can be reduced and the impurities can be effectively removed.

The apparatus of the present invention is characterized in that it is a device for purifying argon gas containing at least oxygen, hydrogen, carbon monoxide, hydrocarbons, oil and nitrogen as impurities, and comprises: an activated carbon adsorption tower into which the argon gas is introduced; a reactor in which argon gas discharged from the above activated carbon adsorption tower is introduced; oxygen supply Adding oxygen to the argon gas introduced into the first reactor; the second reactor, wherein the argon gas flowing out from the first reactor is introduced; and the carbon monoxide feeder, which can be introduced to the first 2 adding carbon monoxide to the argon gas in the reactor; and an adsorption device for introducing argon gas flowing out from the second reactor; wherein the activated carbon adsorption column contains a part of the hydrocarbon adsorbing the argon gas and the oil component In the first reactor, ruthenium is contained as a first reaction catalyst for reacting one of argon gas, carbon, hydrogen, and hydrocarbon with oxygen; and the second reactor contains ruthenium and osmium. Or a mixture of the above as a second reaction catalyst for reacting oxygen in the argon gas with carbon monoxide; the adsorption device includes a PSA (Pressure Swing Absorption) unit, and the PSA unit is transformed by pressure The adsorption method adsorbs at least carbon monoxide, carbon dioxide, water, and nitrogen in the above argon gas.

The method of the invention can be carried out in accordance with the apparatus of the invention.

In the method of the present invention, it is preferred to reduce the water content in the argon gas by a dehydration treatment using a dehydration device between the reaction using the first reaction catalyst and the reaction using the second reaction catalyst. .

Thereby, hydrogen generation can be more reliably prevented by using a mixture of ruthenium, osmium, or the like as the second reaction catalyst to suppress hydrogen generation. In other words, by using a dehydration device before the reaction using the second reaction catalyst, the amount of water in the argon gas is lowered, and the absolute value of the moisture content is lowered, thereby suppressing the effective reaction temperature which changes due to the absolute value of the moisture content. The change is made so that the control of the reaction temperature can be performed more surely. Further, by reducing the amount of water in the argon gas, it is suppressed that one of the catalytic loads is the opposite of carbon oxide and water. Should reduce the load of the catalyst, so that the catalyst can work stably. Thereby, even if the concentration of oxygen, carbon monoxide, and water in the argon gas changes due to the load fluctuation, it is possible to reliably cope with the reaction of the carbon monoxide and the water, and it is possible to reliably prevent the generation of hydrogen. As the dehydration means, for example, a column containing two activated aluminas as a dehydrating agent is preferably used, and the activated alumina of the other column is regenerated by dehydration treatment of one column of activated alumina.

In this case, in the apparatus of the present invention, it is preferable that a dewatering apparatus for reducing the water content in the argon gas flowing out of the first reactor is provided between the first reactor and the second reactor. As the dehydration device, a refrigerator or a column filled with a dehumidifying agent or the like can be used.

In the present invention, it is preferred to use activated alumina and X-type zeolite as the above-mentioned adsorbent for the pressure swing adsorption method.

By using activated alumina as an adsorbent, water absorption and carbon dioxide can be adsorbed/decomposed, so that the adsorption effect of carbon, nitrogen and hydrocarbons by one of the X-type zeolites can be improved. That is, carbon dioxide is relatively difficult to desorb from the X-type zeolite, and the adsorption effect of the X-type zeolite is lowered. When the X-type zeolite filled in the PSA unit is added to increase the adsorption effect, the capacity of the compressor for boosting or the like must be increased. Therefore, there is a problem that the PSA unit is enlarged and the efficiency is lowered. On the other hand, by adsorbing carbon dioxide by activated alumina, the adsorption effect of the X-type zeolite can be improved. Thereby, even if the hydrocarbon remains in the argon gas in the stage before the adsorption treatment by the adsorption device, it is possible to efficiently adsorb the hydrocarbon to the adsorbent by the pressure swing adsorption method without increasing the size of the PSA unit.

Moreover, the adsorption efficiency of carbon monoxide and nitrogen, which is one of the pressure swing adsorption methods, can be improved. Therefore, after the adsorption by the pressure swing adsorption method, it is not necessary to adsorb the nitrogen in the argon gas to the adsorbent by the temperature swing adsorption method at -10 ° C to -50 ° C, and the argon gas can be purified with low energy and high purity. .

In this case, when the weight ratio of the activated alumina to the X-type zeolite is small, the adsorption failure time of nitrogen and hydrocarbons becomes short, and if it becomes large, the adsorption failure time becomes long. Preferably, the activated alumina and the X-type zeolite are arranged in a layer form, and the weight ratio of the activated alumina to the X-type zeolite is set to 5/95 to 30/70. Thereby, the hydrocarbon in the argon gas can be efficiently adsorbed to the adsorbent by the pressure swing adsorption method. As the activated alumina, it is preferably used as a dehumidifier and has a specific surface area of 270 m ² /g or more. As the X-type zeolite, for example, a Li-X type or a Ca-X type can be used, and a Li-X type is particularly preferable.

In the method of the present invention, it is preferred that the nitrogen in the argon gas is adsorbed to the adsorbent by a temperature swing adsorption method at -10 ° C to -50 ° C after adsorption by the pressure swing adsorption method.

Although the nitrogen concentration in the argon gas can be reduced only by the adsorption by the pressure swing adsorption method, the adsorption by the temperature swing adsorption method can reduce the load of the PSA unit for performing the pressure swing adsorption method, which can correspond to The impurity concentration in the argon gas before the purification is changed to surely remove the impurities. Thereby, the purity of the purified argon gas can be further improved. Further, since the oxygen can be removed from the argon gas in the pretreatment stage by the adsorption treatment by the temperature swing adsorption method, the carbon monoxide can be removed by the pressure swing adsorption method, so that the cooling energy during the adsorption treatment by the temperature swing adsorption method can be reduced. Further, since the hydrocarbon can be removed from the argon gas in the pretreatment stage of the adsorption treatment by the temperature swing adsorption method, it is not necessary to remove the nitrogen from the adsorbent when the adsorbent for the temperature swing adsorption method is regenerated. It can reduce the regenerative energy.

In this case, the adsorption device in the device of the present invention preferably comprises a TSA (Thermal Swing Absorption) unit, and the TSA unit is adsorbed from the PSA by a temperature swing adsorption method at -10 ° C to -50 ° C. The nitrogen in the above argon gas flowing out of the unit.

According to the present invention, there can be provided a practical method and apparatus for reducing the load of adsorption treatment, reducing the energy required for purification, and purifying with high purity by reducing the impurity content of argon in the pretreatment stage of the adsorption treatment. The recovered argon gas can be effectively dealt with even when the argon gas contains hydrocarbons and oil.

The argon purification apparatus α shown in Fig. 1 recovers the used argon gas supplied from an argon supply source 1 such as a single crystal crucible or a polycrystalline crucible casting furnace, and purifies it so that it can be reused. The purification device α includes a filter 2, an activated carbon adsorption column 3, a heater 4, a reaction device 5 having a first reactor 5a and a second reactor 5b, a dehydration device 6 having switching valves 6a to 6c, and an adsorption device 7, Oxygen feeder 8, carbon monoxide feeder 9, cooler C, and product storage tank T.

The trace amount of impurities contained in the argon gas before purification is at least oxygen, hydrogen, carbon monoxide, hydrocarbons, oil and nitrogen, and may also contain other impurities such as carbon dioxide and water. The concentration of the impurities in the argon gas before the purification is not particularly limited, and is, for example, about 5 mol ppm to 80000 mol ppm.

The argon gas supplied from the supply source 1 is rotated by, for example, an oil rotary pump (omitted It is collected and collected by the filter 2 (for example, AF1000P manufactured by CKD Co., Ltd.), and then introduced into the activated carbon adsorption column 3 first. The activated carbon adsorption tower 3 contains activated carbon which adsorbs a part of the hydrocarbon in the argon gas and the oil.

It is determined whether the amount of oxygen in the argon gas after one of the hydrocarbons and the oil is adsorbed by the activated carbon exceeds a set amount of oxygen required to react with all of the hydrogen, carbon monoxide, and hydrocarbons in the argon gas. In the present embodiment, the oxygen is set to a stoichiometric amount of oxygen required for the reaction with all of the hydrogen, carbon monoxide, and hydrocarbon in the argon gas.

The amount of oxygen required to completely burn a hydrocarbon varies depending on the type of hydrocarbon contained in the argon gas. Therefore, the above determination is preferably carried out after experimentally determining the composition and concentration of the impurities contained in the argon gas. For example, when the hydrocarbon contained in argon is methane, the reaction formula of hydrogen, carbon monoxide, and methane in argon reacting with oxygen to form water and carbon dioxide is as follows.

H ₂ +1/2O ₂ → H ₂ O CO+1/2O ₂ → CO ₂ CH ₄ +2O ₂ → CO ₂ +2H ₂ O

In this case, the argon is determined according to whether the oxygen molar concentration in the argon exceeds a value equal to 1/2 of the hydrogen molar concentration, 1/2 of the carbon monoxide molar concentration, and 2 times the methane molar concentration. Whether the amount of oxygen in the gas exceeds the above stoichiometry. Of course, the hydrocarbon contained in the argon gas is not limited to methane, and may contain two or more kinds of hydrocarbons.

The above oxygen setting amount is not necessarily the above stoichiometry, as long as it is the above It can be more than the stoichiometry. For example, it is preferably set to a value of 1.05 times to 2.0 times the stoichiometric amount, and by setting it to 1.05 times or more, oxygen in argon gas can be reliably reacted with hydrogen, carbon monoxide, and hydrocarbons, and is set to 2.0. Below this, it is possible to prevent the oxygen concentration from becoming higher than necessary.

When the amount of oxygen in the argon gas is equal to or less than the above-described set amount, oxygen is added to the argon gas by the oxygen supplier 8 so as to exceed the above-described set amount. When the amount of oxygen in the argon gas exceeds the above-described set amount, it is not necessary to perform oxygen addition. In other words, when the amount of oxygen in the argon gas exceeds the above-described set amount, the purification device α directly purifies the argon gas, and when the amount of oxygen is equal to or less than the set amount, the amount exceeds the set amount. The argon gas after the addition of oxygen was purified. When the oxygen supply device 8 that can supply oxygen to the argon gas introduced into the first reactor 5a is provided, when the amount of oxygen in the argon gas is equal to or less than the above-described set amount, the argon can be supplied in excess of the above-mentioned set amount. Add oxygen to the gas.

The oxygen supplier 8 can be composed of, for example, a high-pressure oxygen container having a flow rate control valve, and oxygen can be added to the flow rate corresponding to the introduction flow rate of the argon gas to the first reactor 5a. Furthermore, it is preferable to provide a sampling line for sampling the argon gas introduced into the first reactor 5a before the oxygen supply, and an oxygen analyzer (for example, manufactured by GE Sensing & Inspection Technologies) is disposed on the sampling line. DE-150ε), hydrogen analysis gas chromatograph (such as GC-PDD manufactured by GL science), carbon monoxide analyzer (such as ZRE manufactured by Fuji Electric Systems Co., Ltd.), and total hydrocarbon analyzer (such as FIA manufactured by Horiba Co., Ltd.) 510) Further, an oxygen analyzer and a carbon monoxide analyzer are disposed on the sampling line of the argon gas before being introduced into the second reactor 5b. With this, By continuously monitoring the impurity composition in the argon gas, it is possible to more reliably add the excess oxygen.

The argon gas flowing out of the activated carbon adsorption tower 3 is introduced into the first reactor 5a via the heater 4. In order to complete the reaction in the first reactor 5a, the heating temperature of the argon gas by the heater 4 is preferably 200 ° C or more, and from the viewpoint of preventing the life of the catalyst from being shortened, it is preferably 400 ° C or less. .

Rhenium (Rh) is contained in the first reactor 5a as a first reaction catalyst to cause residual oxygen in the first reactor 5a by reacting one of argon gas, hydrogen, and hydrocarbon with oxygen in the first reactor 5a. Carbon dioxide and water are generated in the state. In the case where the argon gas contains a large amount of a lower hydrocarbon such as methane, it is preferred to set the reaction temperature to 300 ° C or more to allow the reaction to proceed sufficiently. Therefore, it is preferred to use a catalyst in which ruthenium having good heat resistance and high reactivity is supported on alumina. Palladium or the like may be used as a catalyst for reacting carbon monoxide, hydrogen, and a hydrocarbon with oxygen, but ruthenium has higher heat resistance than palladium or the like. As an example of the heat resistance temperature under the present conditions, palladium is 500 ° C to 600 ° C. Platinum (Pt) is 500 ° C ~ 600 ° C, ruthenium (Ru) is about 350 ° C ~ 400 ° C, in contrast, 铑 is about 700 ° C ~ 800 ° C, and durability is also excellent in long-term use. By using the above-mentioned catalyst, the hydrocarbon in the argon gas can be effectively reduced in the first reactor 5a.

The dehydration device 6 is disposed between the first reactor 5a and the second reactor 5b, and can reduce the water content in the argon gas flowing out of the first reactor 5a. In the present embodiment, the argon gas flowing out of the first reactor 5a is introduced into the second reactor 5b via the dehydration device 6 or directly. In other words, the pipe connecting the first reactor 5a and the dewatering device 6 is opened and closed by the switching valve 6a, and the first reactor 5a and the first reactor are provided. The pipe to which the reactor 5b is connected is opened and closed by the switching valve 6b, and the pipe connecting the dehydrating device 6 and the second reactor 5b is opened and closed by the switching valve 6c. By opening the switching valves 6a and 6c and closing the switching valve 6b, the argon gas flowing out of the first reactor 5a is introduced into the second reactor 5b via the dehydrating device 6, and the switching valves 6a and 6c are closed and the switching is turned on. The valve 6b directly introduces the argon gas flowing out of the first reactor 5a into the second reactor 5b. Thereby, when it is not necessary to introduce the argon gas flowing out of the first reactor 5a into the dehydration device 6, the argon gas flowing out from the first reactor 5a can be directly introduced into the second reactor 5b.

The configuration of the dehydration device 6 is not limited as long as the water content in the argon gas can be reduced by dehydration treatment between the reaction using the first reaction catalyst and the reaction using the second reaction catalyst described below. As the dehydration device 6, for example, a pressurized dehydration device that pressurizes argon gas, adsorbs moisture in the argon gas by the adsorbent, and regenerates the adsorbent under reduced pressure; and argon is cooled by pressurization; A refrigerating type dehydrating device that removes moisture and condensed water; a heated regenerative dehydrating device that removes moisture contained in argon gas by a dehydrating agent, and regenerates the dehydrating agent to regenerate it.

Carbon monoxide is added to the argon gas which is discharged from the dehydration device 6 or the first reactor 5a and introduced into the second reactor 5b by the carbon monoxide feeder 9. One of the added carbon oxides is introduced into the second reactor 5b together with the argon gas. By the addition of the carbon monoxide, the amount of carbon monoxide in the argon gas introduced into the second reactor 5b is set to exceed the amount required to react with all of the oxygen remaining in the argon gas. In the present embodiment, the carbon monoxide is set to a stoichiometric amount of carbon monoxide required for reaction with all of the oxygen in the argon gas. In this case, by making one of the argon gases carbon monoxide The degree exceeds twice the oxygen molar concentration measured at the outlet of the first reactor 5a, and the amount of carbon monoxide in the argon gas exceeds the above stoichiometric amount.

The amount of carbon monoxide to be set is not necessarily the above stoichiometric amount, and may be at least the above stoichiometric amount. For example, it is preferably set to a value of 1.05 times to 2.0 times the stoichiometric amount, and by setting it to 1.05 times or more, one of the oxidized carbon in the argon gas can be surely reacted with the residual oxygen to consume residual oxygen, and is set to 2.0. When the ratio is less than the above, it is possible to prevent the concentration of one of the remaining carbon oxides from becoming higher than necessary.

The carbon monoxide supply unit 9 can be composed of, for example, a high-pressure carbon monoxide container having a flow rate control valve, which can add carbon monoxide to a flow rate corresponding to the introduction flow rate of the argon gas to the second reactor 5b. Furthermore, it is preferable to provide a sampling line for sampling the argon gas introduced into the second reactor 5b before the supply of the carbon monoxide, and an oxygen analyzer and a carbon monoxide analyzer are disposed on the sampling line, and 2 The carbon monoxide analyzer is disposed on the sampling line of the argon gas before the reactor 5b flows out and is introduced into the adsorption device 7. Thereby, by continuously monitoring the impurity composition in the argon gas, it is possible to more reliably add a slight excess of carbon monoxide.

In the second reactor 5b, ruthenium (Ru), ruthenium, or the like is contained as a second reaction catalyst so as to be residual by reacting oxygen in the argon gas with carbon monoxide in the second reactor 5b. Carbon dioxide is produced in the presence of carbon monoxide. Preferably, the above ruthenium, osmium, or a mixture of the above is supported on alumina.

The higher the reaction temperature in the second reactor 5b, the easier it is to generate hydrogen due to the reaction of carbon monoxide with water. On the other hand, the lower the reaction temperature, the more the The carbon oxide hinders the poisoning phenomenon of the action of the second reaction catalyst and hinders the reaction of oxygen with carbon monoxide. Further, the higher the residual oxygen concentration in the argon gas introduced into the second reactor 5b, the more the amount of carbon monoxide added is required to promote the reaction of oxygen with carbon monoxide. On the other hand, the more the amount of carbon monoxide added, the more easily hydrogen is generated by the reaction of carbon monoxide with water, and the carbon monoxide is more likely to hinder the action of the second reaction catalyst. Therefore, the oxygen concentration, the carbon monoxide concentration, and the reaction temperature of the argon gas in the second reactor 5b are preferably limited to a range in which appropriate conditions can be obtained for purification. For example, when the reaction temperature is less than 50 ° C, the reactivity of oxygen with carbon monoxide is lowered, and when it is 130 ° C or more, hydrogen is easily generated by the reaction of carbon monoxide with water. Therefore, it is preferred to set the reaction temperature to 50° C. to 130° C., and to set the molar concentration of carbon monoxide to 2.1 times to 2.4 times or less than 3,000 mol ppm of the oxygen molar concentration, and set the molar concentration of oxygen to 1000. Moer ppm or less.

The argon gas flowing out of the second reactor 5b is cooled by the cooler C to lower the moisture and then reaches the adsorption device 7. The adsorption device 7 has a PSA unit 10 and a TSA unit 20.

The PSA unit 10 adsorbs at least carbon monoxide, carbon dioxide, water, and nitrogen in the argon gas to the adsorbent by a pressure swing adsorption method at normal temperature. The argon gas cooled by the cooler C is introduced into the PSA unit 10. Thereby, the carbon dioxide and water generated in the first reactor 5a and the carbon dioxide generated in the second reactor 5b are adsorbed to the adsorption in the PSA unit 10 together with the residual carbon monoxide and the nitrogen originally contained in the argon gas. Agent. Further, in the case where hydrocarbons are left in the argon gas introduced into the PSA unit 10, the hydrocarbons may be adsorbed.

The PSA unit 10 can use a well-known person. For example, the PSA unit 10 shown in FIG. 2 is The four-column type includes a compressor 12 that compresses argon gas flowing out of the second reactor 5b, and four first to fourth adsorption towers 13, and each of the adsorption towers 13 is filled with an adsorbent. The adsorbent is capable of adsorbing carbon monoxide, carbon dioxide, water, and nitrogen. In the present embodiment, activated alumina and X-type zeolite are used, and as the X-type zeolite, a synthetic zeolite of Li-X type or Ca-X type is preferable. . The arrangement of the activated alumina and the X-type zeolite in each adsorption tower 13 is not particularly limited, and for example, it may be layered and alternately arranged. The weight of the activated alumina and the X-type zeolite is preferably set to 5/95 to 30/70. In the case where the two layers are alternately arranged, it is preferred to arrange activated alumina upstream of the argon gas flow path and to arrange the X-type zeolite downstream.

The compressor 12 is connected to the inlet 13a of each adsorption tower 13 via a switching valve 13b.

The inlet 13a of the adsorption tower 13 is connected to the atmosphere via a switching valve 13e and a muffler 13f, respectively.

The outlet 13k of the adsorption tower 13 is connected to the outflow pipe 13m via the switching valve 13l, is connected to the pressure increasing pipe 13o via the switching valve 13n, and is connected to the pressure equalizing/washing side pipe 13q via the switching valve 13p, via the switching valve. 13r is connected to the pressure equalizing/washing inlet side pipe 13s.

The outflow pipe 13m is connected to the product storage tank T via the pressure regulating valve 13t.

The pressure increasing pipe 13o is connected to the outflow pipe 13m via the flow rate control valve 13u and the flow rate indicating regulator 13v, and the flow rate of the argon gas introduced into the product storage tank T is prevented by adjusting the flow rate in the pressure increasing pipe 13o to be fixed. change.

The pressure equalizing/cleaning side pipe 13q and the pressure equalizing/washing inlet pipe 13s are connected to each other via a pair of connecting pipes 13w, and each connecting pipe 13w is provided with Switching valve 13x.

The adsorption step, the pressure reduction I step (clean gas extraction step), the pressure reduction II step (pressure equalization gas extraction step), the desorption step, and the cleaning are sequentially performed in each of the first to fourth adsorption columns 13 of the PSA unit 10. The step (clean gas introduction step), the pressure increase I step (pressure equalization gas introduction step), and the pressure increase step II. Each step will be described below based on the first adsorption tower 13.

In other words, only the switching valve 13b and the switching valve 13l are opened in the first adsorption tower 13, and the argon gas supplied from the second reactor 5b is introduced into the first adsorption tower 13 from the compressor 12 via the switching valve 13b. Thereby, the adsorption step is performed by adsorbing at least nitrogen, carbon monoxide, carbon dioxide, and water in the introduced argon gas to the adsorbent in the first adsorption tower 13, and the argon gas having a lower impurity content is removed from the first adsorption tower. 13 is sent to the product storage tank T via the outflow pipe 13m. At this time, one of the argon gas sent to the outflow pipe 13m is sent to the second adsorption tower 13 via the pressure increasing pipe 13o and the flow rate control valve 13u, and the second adsorption tower 13 performs the pressure increasing step II.

Then, the switching valves 13b and 13l of the first adsorption tower 13 are closed, the switching valve 13p is opened, the switching valve 13r of the fourth adsorption tower 13 is opened, and one of the switching valves 13x is opened. In this way, the argon gas having a relatively small impurity content in the upper portion of the first adsorption tower 13 is sent to the fourth adsorption tower 13 via the pressure equalization/washing inlet side pipe 13s, thereby being reduced in the first adsorption tower 13. Press I step. At this time, the switching valve 13e is opened in the fourth adsorption tower 13, and a washing step is performed.

Then, the switching valve 13p of the first adsorption tower 13 and the switching valve 13r of the fourth adsorption tower 13 are kept open, and the switching valve 13e of the fourth adsorption tower 13 is closed. Thereby, a pressure reduction II step is performed, which is performed on the fourth adsorption tower 13 The gas is recovered until the internal pressure of the first adsorption tower 13 and the fourth adsorption tower 13 becomes uniform or substantially uniform. At this time, the switching valve 13x may be opened both depending on the situation.

Then, by opening the switching valve 13e of the first adsorption tower 13, the switching valve 13p is closed, and the desorption step of desorbing impurities from the adsorbent is performed, and the impurities are released together with the gas to the atmosphere via the muffler 13f.

Then, the switching valve 13r of the first adsorption tower 13 is opened, and the switching valves 13b and 13l of the second adsorption tower 13 in the state where the adsorption step is completed are closed, and the switching valve 13p is opened. In this way, the argon gas having a relatively small impurity content in the upper portion of the second adsorption column 13 is sent to the first adsorption column 13 through the pressure equalization/washing inlet pipe 13s, and is washed in the first adsorption column 13 step. The gas used in the washing step in the first adsorption tower 13 is released to the atmosphere via the switching valve 13e and the muffler 13f. At this time, the pressure reduction I step is performed in the second adsorption tower 13.

Then, the switching valve 13p of the second adsorption tower 13 and the switching valve 13r of the first adsorption tower 13 are kept open, and the switching valve 13e of the first adsorption tower 13 is closed, thereby performing the step of boosting I. At this time, the switching valve 13x may be opened both depending on the situation.

Thereafter, the switching valve 13r of the first adsorption tower 13 is closed. Thereby, it is temporarily a standby state without steps. This state continues until the end of the step 2 of the boosting of the fourth adsorption tower 13. When the pressure increase of the fourth adsorption tower 13 is completed and the adsorption step is switched from the third adsorption tower 13 to the fourth adsorption tower 13, the switching valve 13n of the first adsorption tower is opened. Thereby, one of the argon gas sent from the fourth adsorption tower 13 in the adsorption step to the outflow pipe 13m is sent to the first adsorption tower 13 via the pressure increasing pipe 13o and the flow rate control valve 13u, thereby being adsorbed to the first adsorption column 13 Step-up step in tower 13 Step.

By repeating each of the above steps in the first to fourth adsorption columns 13, the argon gas having a reduced impurity content is continuously supplied to the product storage tank T.

Further, the PSA unit 10 is not limited to the one shown in FIG. 2, and for example, the number of towers may be other than 4, for example, 2 or 3.

Argon gas containing nitrogen not adsorbed to the adsorbent in the PSA unit 10 is introduced into the TSA unit 20. The TSA unit 20 adsorbs nitrogen in the argon gas to the adsorbent by a temperature swing adsorption method at -10 ° C to -50 ° C.

The TSA unit 20 can use a well-known person. For example, the TSA unit 20 shown in FIG. 3 is a 2-tower type, and includes a heat exchange type pre-cooler 21 that pre-cools argon gas sent from the PSA unit 10, and further cools the argon gas cooled by the pre-cooler 21. The heat exchange cooler 22, the first and second adsorption towers 23, and the heat exchange unit 24 covering the adsorption towers 23. The heat exchange unit 24 cools the adsorbent by a refrigerant during the adsorption step, and heats the adsorbent with a heat medium during the desorption step. Each adsorption tower 23 has a plurality of inner tubes filled with an adsorbent. As the adsorbent, an adsorber suitable for nitrogen is used. For example, an X-type zeolite-based adsorbent obtained by ion exchange with calcium (Ca) or lithium (Li) is preferably used, and more preferably, it is ion-exchanged. The rate is 70% or more, and it is particularly preferable to set the specific surface area to 600 m ² /g or more.

The cooler 22 is connected to the inlet 23a of each adsorption tower 23 via the switching valve 23b.

The inlet 23a of the adsorption tower 23 is communicated to the atmosphere via the switching valve 23c, respectively.

The outlet 23e of the adsorption tower 23 is connected to the outflow pipe 23g via the switching valve 23f, is connected to the cooling/boosting pipe 23i via the switching valve 23h, and is connected to the cleaning pipe 23k via the switching valve 23j.

The outflow pipe 23g constitutes a part of the precooler 21, and the argon gas sent from the PSA unit 10 is cooled by the purified argon gas flowing out from the outflow pipe 23g. The purified argon gas flows out from the outflow pipe 23g via the switching valve 23l.

The cooling/boosting pipe 23i and the cleaning pipe 23k are connected to the outflow pipe 23g via the flow meter 23m, the flow rate control valve 23o, and the switching valve 23n.

The heat exchange unit 24 is a multi-tube type, and includes a plurality of inner tube outer tubes 24a constituting the adsorption tower 23, a refrigerant supply source 24b, a refrigerant radiator 24c, a heat medium supply source 24d, and a heat medium radiator 24e. . Further, a plurality of switching valves 24f for circulating the refrigerant supplied from the refrigerant supply source 24b through the outer tube 24a and the refrigerant radiator 24c and the self-heating medium supply source 24d are provided. The supplied heat medium is switched between the states in which the outer tube 24a and the heat medium radiator 24e circulate. Further, a pipe branched from the refrigerant radiator 24c constitutes a part of the cooler 22, and the refrigerant supplied from the refrigerant supply source 24b in the cooler 22 cools the argon gas, and the refrigerant flows back into the storage tank 24g.

The adsorption step, the desorption step, the washing step, the cooling step, and the step of increasing the pressure are sequentially performed in each of the first and second adsorption towers 23 of the TSA unit 20.

In other words, in the TSA unit 20, the argon gas supplied from the PSA unit 10 is cooled in the precooler 21 and the cooler 22, and then introduced into the first adsorption tower 23 via the switching valve 23b. At this time, the first adsorption tower 23 is cooled to -10 ° C to -50 ° C by the refrigerant circulation in the heat exchanger 24, and the switching valve is closed. 23c, 23h, and 23j, the switching valve 23f is opened, and at least nitrogen contained in the argon gas is adsorbed to the adsorbent. Thereby, the adsorption step is performed in the first adsorption tower 23, and the purified argon gas having a reduced impurity content rate flows out from the adsorption tower 23 via the switching valve 23l, and is sent to the product storage tank T.

During the adsorption step in the first adsorption tower 23, a desorption step, a washing step, a cooling step, and a pressure increasing step are performed in the second adsorption tower 23.

In other words, in the second adsorption tower 23, after the adsorption step is completed, in order to carry out the desorption step, the switching valves 23b and 23f are closed, and the switching valve 23c is opened. Thereby, in the second adsorption tower 23, argon gas containing impurities is released into the atmosphere, and the pressure is lowered to substantially atmospheric pressure. In the second adsorption tower 23, the switching valve 24f of the heat exchange unit 24 that circulates the refrigerant in the adsorption step is switched to the closed state to stop the circulation of the refrigerant, and the refrigerant is discharged from the heat exchange unit 24. The switching valve 24f returned to the refrigerant supply source 24b is switched to the open state.

Then, in order to perform the washing step in the second adsorption tower 23, the switching valves 23c and 23j of the second adsorption tower 23 and the switching valve 23n of the cleaning piping 23k are turned on, and the heat exchange type precooler is used. One part of the purified argon heated by the heat exchange in the 21st is introduced into the second adsorption tower 23 through the cleaning pipe 23k. Thereby, in the second adsorption tower 23, desorption of impurities from the adsorbent and washing by the purified argon gas are performed, and the argon gas used for the cleaning is released together with the impurities from the switching valve 23c to the atmosphere. In the cleaning step, the switching valve 24f of the heat exchange unit 24 for circulating the heat medium is switched to the open state in the second adsorption tower 23.

Then, in order to perform the cooling step in the second adsorption tower 23, the second adsorption is performed. The switching valve 23j of the column 23 and the switching valve 23n of the cleaning pipe 23k are in a closed state, and the switching valve 23h of the second adsorption tower 23 and the switching valve 23n of the cooling/boosting pipe 23i are turned on. One of the purified argon gas flowing out of the first adsorption tower 23 is introduced into the second adsorption tower 23 via the cooling/boosting pipe 23i. Thereby, the purified argon gas cooled in the second adsorption tower 23 is discharged to the atmosphere via the switching valve 23c. In the cooling step, the switching valve 24f for circulating the heat medium is switched to the closed state to stop the heat medium circulation, and the heat medium is discharged from the heat exchange unit 24 and returned to the heat medium supply source 24d. The switching valve 24f is switched to the open state. After the discharge of the heat medium is completed, the switching valve 24f of the heat exchange unit 24 for circulating the refrigerant is switched to the open state in the second adsorption tower 23 to be in a refrigerant circulation state. The refrigerant circulation state continues until the next step of boosting, and the subsequent adsorption step is completed.

Then, in order to carry out the pressure increasing step in the second adsorption tower 23, the switching valve 23c of the second adsorption tower 23 is closed, and a part of the purified argon gas flowing out from the first adsorption tower 23 is introduced thereinto, thereby making the second The inside of the adsorption tower 23 is boosted. This pressure increasing step continues until the internal pressure of the second adsorption tower 23 becomes substantially equal to the internal pressure of the first adsorption tower 23. When the pressure increasing step is completed, the switching valve 23h of the second adsorption tower 23 and the switching valve 23n of the cooling/boosting piping 23i are closed, whereby all the switching valves 23b, 23c, 23f, 23h, 23j of the second adsorption tower 23 are closed. All of them are in a closed state, and the second adsorption tower 23 is in a standby state until the next adsorption step.

The adsorption step of the second adsorption tower 23 is carried out in the same manner as the adsorption step of the first adsorption tower 23. The adsorption step is performed in the second adsorption tower 23 The desorption step, the washing step, the cooling step, and the pressure increasing step are performed in the first adsorption tower 23 in the same manner as in the second adsorption tower 23.

Further, the TSA unit 20 is not limited to the one shown in FIG. 3, and for example, the number of towers may be 2 or more, for example, 3 or 4.

According to the purification apparatus α, when argon gas containing at least oxygen, hydrogen, carbon monoxide, hydrocarbons, oil, and nitrogen as impurities is recovered and purified, the oil contained in the argon gas is adsorbed by the activated carbon. Further, the activated carbon can also adsorb a part of the hydrocarbon derived from the oil component, and in particular, the hydrocarbon having a carbon number of 1 to 6 can be efficiently adsorbed by the activated carbon. Then, it is determined whether the amount of oxygen in the argon gas exceeds a set amount of oxygen required to react with all of hydrogen, carbon monoxide, and hydrocarbons in the argon gas, and when the amount of oxygen is less than the above-described set amount, the amount exceeds the set amount. Add oxygen in the same way. Thereafter, ruthenium is used as the first reaction catalyst to cause carbon monoxide, hydrogen, and hydrocarbons in the argon gas to react with oxygen, whereby carbon dioxide and water are generated in a state in which oxygen remains. Thereby, the main impurities in the argon gas are carbon dioxide, water, oxygen, and nitrogen. Then, carbon monoxide is added in such a manner that the amount of carbon monoxide in the argon gas exceeds the amount required to react with all of the remaining residual oxygen. Thereafter, a mixture of ruthenium, osmium, or the like is used as a second reaction catalyst to react oxygen in argon with carbon monoxide, thereby generating carbon dioxide in a state in which carbon monoxide remains. Thereby, the main impurities in the argon gas are water, carbon monoxide, carbon dioxide, and nitrogen. Thereafter, one of carbon monoxide, carbon dioxide, water, and nitrogen in the argon gas is adsorbed to the adsorbent by a pressure swing adsorption method, and the particles are removed from the argon gas.

That is, the purification apparatus α reduces the amount of hydrocarbons in the argon gas by efficiently adsorbing the oil and the hydrocarbon having a carbon number of 1 to 6 by using the activated carbon. Thereby, the cause can be reduced Subsequent hydrocarbons react with oxygen to form water and carbon dioxide, and the adsorption load in the subsequent adsorption device 7 can be alleviated. Moreover, since the heat used for the first reaction catalyst is excellent in heat resistance and high in reactivity, when the argon gas contains a large amount of a lower hydrocarbon such as methane, the reaction temperature can be raised and the reaction proceeds sufficiently. Effectively reduce hydrocarbons in argon. Further, by using ruthenium, osmium, or a mixture thereof as the second reaction catalyst, the reaction between water and carbon monoxide can be suppressed to prevent generation of hydrogen. Thereby, since hydrogen which is hard to be removed by the adsorption treatment by the adsorption device 7 can be prevented from remaining in the argon gas, the argon gas can be purified with high purity. Further, since oxygen can be removed from the argon gas in the pretreatment stage of the adsorption treatment by the adsorption device 7, the purification load can be reduced, and the impurities can be effectively removed by the adsorption device 7. Further, by using activated alumina and X-type zeolite as an adsorbent for pressure swing adsorption, activated carbon can be used for adsorption and desorption of water and carbon dioxide in argon gas, thereby improving oxidation of carbon using one of X-type zeolites. , nitrogen and hydrocarbon adsorption effects. Thereby, even if the hydrocarbon remains in the argon gas in the stage before the adsorption treatment by the adsorption device 7, it is possible to efficiently adsorb the hydrocarbon to the adsorbent by the pressure swing adsorption method without increasing the size of the PSA unit 10.

Further, according to the purification apparatus α, the water content in the argon gas can be reduced by the dehydration treatment using the dehydration device between the reaction using the first reaction catalyst and the reaction using the second reaction catalyst. Thereby, the reaction of water and carbon monoxide can be surely suppressed to prevent the generation of hydrogen.

Further, according to the purification apparatus α, after adsorbing impurities by the pressure swing adsorption method, nitrogen in the argon gas can be adsorbed to the adsorbent by a temperature swing adsorption method at -10 ° C to -50 ° C. By using the temperature swing adsorption method in combination as described above The adsorption can reduce the load of the PSA unit 10, and the impurities are surely removed in accordance with the fluctuation of the impurity concentration in the argon gas before purification. Therefore, the purity of the purified argon gas can be further improved. Further, in the pretreatment stage of the adsorption treatment by the temperature swing adsorption method, oxygen can be removed from the argon gas, and the carbon monoxide can be removed by the pressure swing adsorption method, so that the cooling energy in the adsorption treatment by the temperature swing adsorption method can be reduced. Further, since the hydrocarbon can be removed from the argon gas in the pretreatment stage of the adsorption treatment by the temperature swing adsorption method, the regeneration of the adsorbent for the temperature swing adsorption method does not require the removal of the nitrogen from the adsorbent, but can be reduced. Regeneration energy. Further, by using activated alumina and X-type zeolite as the adsorbent in the PSA unit 10, the nitrogen adsorption effect can be enhanced, so that the nitrogen adsorption load in the TSA unit 20 can be alleviated, and the recovered product can be purified with higher purity. Argon.

[Example 1]

Purification of argon gas was carried out using the above purification apparatus α. The argon gas before purification contains the following as impurities: oxygen 200 mol ppm, hydrogen 50 mol ppm, carbon monoxide 1000 mol ppm, nitrogen 750 mol ppm, carbon dioxide 60 mol ppm, water 500 mppm ppm, as a hydrocarbon The methane is 20 mol ppm, and the C2 to C6 hydrocarbon is 32 mol ppm in terms of C1 hydrocarbon conversion, and the oil content is 4.5 g/m ³ . The above argon gas was introduced into the activated carbon adsorption column 3 at a flow rate of 4.0 L/min under standard conditions. The activated carbon adsorption column 3 was set to have a tubular shape with a nominal diameter of 32 A and was filled with GX6/8 molding carbon 10 L manufactured by Japan Enviro Chemicals.

Then, oxygen was supplied from the oxygen supply device 8 to the argon gas flowing out of the activated carbon adsorption column 3 at a flow rate of 3.2 ml/min, and introduced into the first reactor 5a. Filled with alumina in the first reactor 5a (manufactured by NE CHEMCAT) 0.5% alumina particles) 60 mL, and the reaction conditions were set to a temperature of 350 ° C, atmospheric pressure, and a space velocity of 4000 / h. In this case, the oxygen contained in the argon gas is about 1.6 times the theoretical value required for the reaction with hydrogen, carbon monoxide, and a hydrocarbon. Carbon monoxide was supplied from the carbon monoxide supply unit 9 to the argon gas flowing out of the first reactor 5a at a flow rate of 3.6 ml/min, and introduced into the second reactor 5b. In this case, one of the oxidized carbon contained in the argon gas is about 1.2 times the theoretical value required to consume residual oxygen. The second reactor 5b was filled with 60 ml of an alumina-supported catalyst (RUA3MM manufactured by Sud-Chemie Co., Ltd.) under the conditions of a temperature of 110 ° C, an atmospheric pressure, and a space velocity of 4000 / h.

The argon gas flowing out of the second reactor 5b is cooled, and the impurity content is lowered by the adsorption device 7. The PSA unit 10 is a four-tower type, and each column is set to have a nominal diameter of 32 A and a length of 1 m. The columns are filled with activated alumina (KHD-24 manufactured by Sumitomo Chemical Co., Ltd.) 10 wt%, Li-X. The zeolite (NSA-700 manufactured by Tosoh) is 90 wt% as an adsorbent. The operating conditions of the PSA unit 10 were set to an adsorption pressure of 0.8 MPaG, a desorption pressure of 10 kPaG, a cycle time of 400 sec/tower, and a pressure equalization of 15 sec. The TSA unit 20 is a two-stage type, and each column is filled with 1.25 L of Ca-X type zeolite (SA-600A manufactured by Tosoh) as an adsorbent, and the adsorption pressure is set to 0.8 MPaG, and the adsorption temperature is set to -35 ° C. The desorption pressure was set to 0.1 MPaG, and the desorption temperature was set to 40 °C.

In this case, the impurity composition of the outlet of the first reactor 5a, the outlet of the second reactor 5b, the outlet of the PSA unit 10, and the outlet of the TSA unit 20 is as shown in Table 1 below. The composition of the hydrocarbons in Table 1 represents the total of the methane concentration and the C1 hydrocarbon-converted concentration of the C2 to C6 hydrocarbons.

Further, the composition of the argon gas at the outlet of the activated carbon adsorption column 3 is as follows.

‧ Activated carbon adsorption tower outlet

Hydrogen: 50 mole ppm, oxygen: 200 mole ppm, nitrogen: 750 mole ppm, carbon monoxide: 1000 mole ppm, carbon dioxide: 60 mole ppm, methane: 20 mole ppm, C2 to C6 hydrocarbon: C1 hydrocarbon Conversion is 30 mole ppm, moisture: 500 mole ppm, oil: less than 0.1 g/m ³

Further, the oxygen concentration in the purified argon gas was measured by an oxygen analyzer DE-150 ε manufactured by GE Sensing & Inspection Technologies, and the concentrations of carbon monoxide and dioxin were passed through a methanizer and using Shimadzu. The GC-FID manufactured by the manufacturer was measured, and the hydrogen concentration was measured by GC-PDD manufactured by GL Science Co., Ltd., and the nitrogen concentration was measured by a trace nitrogen analyzer PES-2000 manufactured by ROUND SCIENCE, and the hydrocarbon concentration was measured. The measurement was carried out by GC-FID manufactured by Shimadzu Corporation, and the oil fraction was obtained by calculation based on the filtration increment of the filter VFA1000 manufactured by CKD, and the moisture was carried out using a dew point meter DEWMET-2 manufactured by GE Sensing & Inspection Technologies. Determination.

[Embodiment 2]

The catalyst used in the second reactor 5b was made of alumina supported (0.5% alumina particles manufactured by NE CHEMCAT). Except for this, argon gas was purified under the same conditions as in Example 1.

The impurity composition of the outlet of the first reactor 5a, the outlet of the second reactor 5b, the outlet of the PSA unit 10, and the outlet of the TSA unit 20 in this case is shown in Table 1.

[Comparative Example 1]

The catalyst used in the first reactor 5a is alumina-supported platinum (DASH-220 manufactured by NE CHEMCAT), and the catalyst used in the second reactor 5b is alumina-supported platinum. (DASH-220 manufactured by NE CHEMCAT). Further, only Li-X type zeolite was filled in the adsorption tower of the PSA unit 10 as an adsorbent. Except for this, argon gas was purified under the same conditions as in Example 1.

The impurity composition of the outlet of the first reactor 5a, the outlet of the second reactor 5b, the outlet of the PSA unit 10, and the outlet of the TSA unit 20 in this case is shown in Table 1.

[Example 3]

The argon gas flowing out of the first reactor 5a was introduced into the dehydration unit 6 at a flow rate of 4.0 L/min in a standard state. The dewatering device 6 was set to have a tubular shape with a nominal diameter of 32 A and was filled with activated alumina (KHD-24 manufactured by Sumitomo Chemical Co., Ltd.) 8 L. Carbon monoxide was supplied from the carbon monoxide supply unit 9 to the argon gas flowing out of the dehydration unit 6 at a flow rate of 3.6 ml/min, and introduced into the second reactor 5b. In this case, one of the oxidized carbon contained in the argon gas is about 1.2 times the theoretical value required to consume residual oxygen. Except for this, argon gas was purified under the same conditions as in Example 1.

The impurity composition of the outlet of the first reactor 5a, the outlet of the second reactor 5b, the outlet of the PSA unit 10, and the outlet of the TSA unit 20 in this case is shown in Table 2.

[Example 4]

The argon gas flowing out of the first reactor 5a was introduced into the dehydration unit 6 at a flow rate of 4.0 L/min in a standard state. The dewatering device 6 was set to have a tubular shape with a nominal diameter of 32 A and was filled with activated alumina (KHD-24 manufactured by Sumitomo Chemical Co., Ltd.) 8 L. Carbon monoxide was supplied from the carbon monoxide supply unit 9 to the argon gas flowing out of the dehydration unit 6 at a flow rate of 3.6 ml/min, and introduced into the second reactor 5b. In this case, one of the oxidized carbon contained in the argon gas is about 1.2 times the theoretical value required to consume residual oxygen. Except for this, argon gas was purified under the same conditions as in Example 2.

The impurity composition of the outlet of the first reactor 5a, the outlet of the second reactor 5b, the outlet of the PSA unit 10, and the outlet of the TSA unit 20 in this case is shown in Table 2.

[Comparative Example 2]

The argon gas flowing out of the first reactor 5a was introduced into the dehydration unit 6 at a flow rate of 4.0 L/min in a standard state. The dewatering device 6 was set to have a tubular shape with a nominal diameter of 32 A and was filled with activated alumina (KHD-24 manufactured by Sumitomo Chemical Co., Ltd.) 8 L. Carbon monoxide was supplied from the carbon monoxide supply unit 9 to the argon gas flowing out of the dehydration unit 6 at a flow rate of 3.6 ml/min, and introduced into the second reactor 5b. In this case, one of the oxidized carbon contained in the argon gas is about 1.2 times the theoretical value required to consume residual oxygen. Except for this, argon gas was purified under the same conditions as in Comparative Example 1.

The impurity composition of the outlet of the first reactor 5a, the outlet of the second reactor 5b, the outlet of the PSA unit 10, and the outlet of the TSA unit 20 in this case is shown in Table 2.

[Comparative Example 3]

The pretreatment of the adsorption treatment was not carried out, and the purification of argon gas was performed only by the adsorption treatment using the PSA unit 10 and the TSA unit 20. The argon gas before purification contained 5000 ppm of carbon monoxide, 5000 ppm of nitrogen, and 1 mol% of carbon dioxide as impurities. The PSA unit 10 is a 4-tower type, and each column is set to have a nominal diameter of 32 A and a length of 1 m. The columns are filled with activated alumina (KHD-24 manufactured by Sumitomo Chemical Co., Ltd.) 10 wt% and Ca-A. Zeolite (5A-HP manufactured by UOP) is 90 wt% as an adsorbent. The operating conditions of the PSA unit 10 were set to an adsorption pressure of 0.8 MPaG, a desorption pressure of 10 kPaG, a cycle time of 710 sec/tower, and argon gas was purified under a pressure equalization of 15 sec. The TSA unit 20 is a two-stage type, and each column is filled with 1.25 L of Ca-X type zeolite (SA-600A manufactured by Tosoh) as an adsorbent, and the adsorption pressure is set to 0.8 MPaG, and the adsorption temperature is set to -35 ° C. The desorption pressure was set to 0.1 MPaG, and the desorption temperature was set to 40 °C.

The impurity composition of the outlet of the PSA unit 10 and the outlet of the TSA unit 20 at this time is shown in Table 3. Further, the recovery rate of argon gas at the outlet of the PSA unit 10 was 65.3%.

[Comparative Example 4]

The adsorption tower of the PSA unit 10 is filled with 30 wt% of activated alumina (KHD-24 manufactured by Sumitomo Chemical Co., Ltd.) and 70 wt% of Li-X type zeolite (NSA-700 manufactured by Tosoh) as an adsorbent, and the cycle time is set. It is 1000 sec/tower. except Except that, argon gas was purified under the same conditions as in Comparative Example 3.

The impurity composition of the outlet of the PSA unit 10 and the outlet of the TSA unit 20 at this time is shown in Table 3. Further, the recovery rate of argon gas at the outlet of the PSA unit 10 was 75.2%.

[Comparative Example 5]

The adsorption tower of the PSA unit 10 is filled with activated alumina (KHD-24 manufactured by Sumitomo Chemical Co., Ltd.) 10 wt% and Li-X zeolite (NSA-700 manufactured by Tosoh) 90 wt% as an adsorbent, and the cycle time is set. It is 770 sec/tower. Except for this, argon gas was purified under the same conditions as in Comparative Example 3.

The impurity composition of the outlet of the PSA unit 10 and the outlet of the TSA unit 20 at this time is shown in Table 3. Further, the recovery rate of argon gas at the outlet of the PSA unit 10 was 69%.

The following aspects can be confirmed from the above respective examples and comparative examples.

It was confirmed that hydrocarbons can be efficiently reacted by using a ruthenium catalyst in the first reactor 5a, and hydrogen generation can be prevented by using ruthenium or ruthenium catalyst in the second reactor 5b.

It was confirmed that the adsorbent used in the pressure swing adsorption method can be effectively adsorbed by using the activated alumina and the X-type zeolite.

From Examples 1 and 2, it was confirmed that the nitrogen concentration of the argon gas at the outlet of the PSA unit 10 was sufficiently lowered, and the recovered argon gas was purified with high purity. Further, it can be confirmed that the nitrogen concentration of the argon gas at the outlet of the TSA unit 20 is further lowered.

Although the nitrogen concentration of the argon gas at the outlet of the PSA unit 10 in Comparative Example 5 was lower than the nitrogen concentration of the argon gas at the outlet of the PSA unit 10 in Comparative Example 4, the cycle time of Comparative Example 5 was shorter than that of Comparative Example 4. Therefore, more argon gas is discarded, and the recovery rate of argon gas is lowered. On the other hand, the nitrogen concentration of the argon gas at the outlet of the TSA unit 20 in Comparative Example 4 and Comparative Example 5 was lowered to the same extent. Therefore, it can be confirmed that the load of the PSA unit can be alleviated by using the TSA unit in combination.

It can be confirmed from Comparative Examples 3 and 5 that the adsorbent used for the pressure swing adsorption method is made of activated alumina and Li-X type zeolite, and compared with the case of using activated alumina and Ca-A type zeolite. Reduce the nitrogen concentration of the argon after purification. Further, from Comparative Examples 4 and 5, it was confirmed that the nitrogen concentration of argon gas can be sufficiently reduced even when the purification is carried out only by the adsorption treatment.

The present invention is not limited to the above embodiments or examples. For example, a machine for recovering argon gas is not limited to a machine using oil such as an oil rotary vacuum pump, and for example, an oil-free vacuum pump can also be used. Further, the TSA unit may be omitted depending on the purity of the argon gas.

1‧‧‧ argon supply source

2‧‧‧Filter

3‧‧‧Active carbon adsorption tower

4‧‧‧heater

5‧‧‧Reaction device

5a‧‧‧1st reactor

5b‧‧‧2nd reactor

6‧‧‧Dehydration device

6a, 6b, 6c‧‧‧ switching valve

7‧‧‧Adsorption device

8‧‧‧Oxygen feeder

9‧‧‧ Carbon monoxide feeder

10‧‧‧PSA unit

20‧‧‧TSA unit

C‧‧‧cooler

T‧‧‧ product storage tank

‧‧‧‧purification unit

Fig. 1 is an explanatory view showing the configuration of an apparatus for purifying an argon gas according to an embodiment of the present invention.

Fig. 2 is a block diagram showing the configuration of a PSA unit in an apparatus for purifying argon gas according to an embodiment of the present invention.

Fig. 3 is a block diagram showing the configuration of a TSA unit in an apparatus for purifying argon gas according to an embodiment of the present invention.

1‧‧‧ argon supply source

2‧‧‧Filter

3‧‧‧Active carbon adsorption tower

4‧‧‧heater

5‧‧‧Reaction device

5a‧‧‧1st reactor

5b‧‧‧2nd reactor

6‧‧‧Dehydration device

6a, 6b, 6c‧‧‧ switching valve

7‧‧‧Adsorption device

8‧‧‧Oxygen feeder

9‧‧‧ Carbon monoxide feeder

10‧‧‧PSA unit

20‧‧‧TSA unit

C‧‧‧cooler

T‧‧‧ product storage tank

‧‧‧‧purification unit

Claims (6)

A method for purifying argon gas, which is a method for purifying argon gas containing at least oxygen, hydrogen, carbon monoxide, hydrocarbons, oil and nitrogen as impurities, which is to adsorb a part of a hydrocarbon in the argon gas and an oil component to an activity Carbon; then determining whether the amount of oxygen in the argon gas exceeds a set amount required to react with all of the hydrogen, carbon monoxide, and hydrocarbons in the argon gas; and the amount of oxygen in the argon gas is less than the above-mentioned set amount When oxygen is added in excess of the above-mentioned amount, the ruthenium is used as the first reaction catalyst, and one of the argon gases, carbon monoxide, hydrogen, and hydrocarbons are reacted with oxygen, whereby the oxygen remains. Producing carbon dioxide and water; then, adding carbon monoxide in such a manner that one of the argon gases exceeds the amount required to react with all of the residual oxygen; and then using ruthenium, osmium, or a mixture thereof as the second reaction The oxygen in the argon gas is reacted with carbon monoxide by a catalyst, thereby generating carbon dioxide in a state in which carbon monoxide remains; and then, by pressure swinging The method of adsorbing at least carbon monoxide, carbon dioxide, water, and nitrogen in the argon gas to the adsorbent; and using dehydration between the reaction using the first reaction catalyst and the reaction using the second reaction catalyst The dehydration treatment of the apparatus reduces the moisture content in the above argon gas. The method for purifying argon gas according to claim 1, wherein the activated alumina and the X-type zeolite are used as the above-mentioned adsorbent for the pressure swing adsorption method. The method for purifying argon gas according to claim 2, wherein the activated alumina and the X-type zeolite are disposed in a layer form, and the weight ratio of the activated alumina to the X-type zeolite is set to 5/95 to 30 /70. The method for purifying argon gas according to any one of claims 1 to 3, wherein after the adsorption by the pressure swing adsorption method, the nitrogen in the argon gas is obtained by a temperature swing adsorption method at -10 ° C to -50 ° C Adsorbed to the adsorbent. An apparatus for purifying argon gas, which is characterized in that it is a device for purifying argon gas containing at least oxygen, hydrogen, carbon monoxide, hydrocarbons, oil and nitrogen as impurities, and comprises: an activated carbon adsorption tower, into which the argon is introduced a first reactor in which argon gas discharged from the activated carbon adsorption column is introduced; an oxygen supplier that adds oxygen to the argon gas introduced into the first reactor; and a second reactor in which Introducing argon gas flowing out from the first reactor; a carbon monoxide supply unit for adding carbon monoxide to argon gas introduced into the second reactor; and an adsorption device for introducing argon flowing out from the second reactor a gas in which the activated carbon adsorbing a part of the hydrocarbon in the argon gas and the oil are contained in the activated carbon adsorption tower; and the first reactor contains the ruthenium as one of the argon gas, carbon, hydrogen, and hydrocarbon a catalyst for the first reaction in which oxygen is reacted; The second reactor contains a mixture of ruthenium, osmium, or the like as a second reaction catalyst for reacting oxygen in the argon gas with carbon monoxide; the adsorption device includes a PSA unit, and the PSA unit is At least carbon monoxide, carbon dioxide, water, and nitrogen in the argon gas are adsorbed by a pressure swing adsorption method; and between the first reactor and the second reactor, an argon gas which is discharged from the first reactor is provided. The water content dewatering device. The argon purifying apparatus of claim 5, wherein the adsorption device comprises a TSA unit, wherein the TSA unit adsorbs nitrogen in the argon gas flowing out from the PSA unit by a temperature swing adsorption method at -10 ° C to -50 ° C .