JP2013010679A - Method and apparatus for purifying argon gas - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce an impurity content of argon gas in a pretreatment stage of an adsorption treatment; to reduce energy necessary for purification; and to purify the argon gas so as to be highly pure.SOLUTION: When purifying argon gas containing at least oxygen, hydrogen, carbon monoxide, hydrocarbons, oil and nitrogen, a part of hydrocarbons and oil are adsorbed by active carbon. Then, when the amount of oxygen in the argon gas is smaller than a set amount of oxygen necessary for reactions with all of hydrogen, carbon monoxide and hydrocarbons, oxygen is added so as to exceed the set amount, and the reactions are generated by using a catalyst. Thereafter, carbon monoxide is added to the argon gas so as to exceed a set amount necessary for a reaction with all oxygen remaining in the reaction, and the reaction is generated by using ruthenium, palladium or a mixed catalyst thereof. Subsequently, carbon monoxide, carbon dioxide, water and nitrogen in the argon gas are adsorbed onto an adsorbent by a pressure swing adsorption method.

Description

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

  For example, in equipment such as silicon single crystal pulling furnace, ceramic sintering furnace, vacuum degassing equipment for steel making, silicon plasma melting equipment for solar cells, polycrystalline silicon casting furnace, argon gas is used as atmosphere gas in the furnace Has been. The purity of argon gas collected for reuse from such facilities is reduced due to the incorporation of hydrogen, carbon monoxide, air, and the like. Therefore, in order to increase the purity of the recovered argon gas, the admixed impurities are adsorbed on the adsorbent. Furthermore, in order to efficiently adsorb such impurities, it has been proposed to react oxygen in the impurities and combustible components to denature them into carbon dioxide and water as a pretreatment of the adsorption treatment (Patent Document 1). 2).

  In the method disclosed in Patent Document 1, the amount of oxygen in the argon gas is adjusted to be slightly less than the stoichiometric amount necessary for complete combustion of combustible components such as hydrogen and carbon monoxide, Next, using palladium or gold, which gives priority to the reaction between hydrogen and oxygen over the reaction between carbon monoxide and oxygen, oxygen in argon gas is reacted with carbon monoxide, hydrogen, etc. Carbon dioxide and water are produced in the state where only the residue remains. Next, carbon dioxide and water contained in argon gas are adsorbed on the adsorbent at room temperature, and then carbon monoxide and nitrogen contained in argon gas are made into the adsorbent at a temperature of −10 ° C. to −50 ° C. Adsorbed.

  In the method disclosed in Patent Document 2, the amount of oxygen in the argon gas is set to an amount sufficient to completely combust combustible components such as hydrogen and carbon monoxide, and then argon is used using a palladium-based catalyst. By reacting oxygen in the gas with carbon monoxide, hydrogen, or the like, carbon dioxide and water are generated with oxygen remaining. Next, carbon dioxide and water contained in the argon gas are adsorbed on the adsorbent at room temperature, and then oxygen and nitrogen contained in the argon gas are adsorbed on the adsorbent at a temperature of about −170 ° C.

  In the method disclosed in Patent Document 3, when the oil content is contained in the argon gas discharged from the single crystal production furnace or the like, the oil content is removed using an oil removal cylinder or an oil removal filter containing activated carbon or the like. ing. Next, oxygen in the argon gas introduced into the catalyst cylinder is reacted with added hydrogen to be converted into water. Next, water and carbon dioxide in the argon gas introduced into the adsorption cylinder are adsorbed and removed, and then purified by a rectification operation.

  In the method disclosed in Patent Document 4, in order to purify an argon gas containing carbon monoxide, hydrogen, oxygen, and nitrogen as impurities, carbon monoxide and hydrogen in the argon gas are reacted with oxygen to obtain carbon monoxide. Carbon dioxide and water are produced in a state where the water remains. Next, carbon dioxide, water, nitrogen and carbon monoxide in argon gas are adsorbed on the adsorbent at 10 to 50 ° C., and the adsorbent is regenerated at 150 to 400 ° C. Moreover, in order to adsorb | suck nitrogen in argon gas, the copper ion exchange ZSM-5 type zeolite (copper ion exchange rate 121%) is used as an adsorbent.

Japanese Patent No. 3496079 Japanese Patent No. 3737900 JP 2000-88455 A JP 2006-111506 A

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

  In the method described in Patent Document 2, oxygen remains in the pretreatment stage by setting the amount of oxygen contained as an impurity in the argon gas to an amount sufficient to completely burn hydrogen, carbon monoxide, and the like. It produces carbon dioxide and water. However, after that, in order to adsorb the remaining oxygen, it is necessary to lower the temperature at the time of adsorption to about -170 ° C. That is, since oxygen remains in the pretreatment stage of the adsorption treatment, there is a problem that the cooling energy during the adsorption treatment increases and the purification load increases.

  In the method described in Patent Document 3, oil contained in argon gas is removed by adsorbing it on activated carbon. However, when recovering the argon gas, for example, when using equipment such as an oil rotary vacuum pump that uses oil to maintain airtightness, a hydrocarbon component is generated by thermally decomposing the oil, and the oil removal mist Even if there is a separator, it will come off the mist separator. Then, hydrocarbons derived from the oil contained in the argon gas are several hundreds of methane in terms of tens of ppm or more and hydrocarbons having 2 to 5 carbon atoms (C2 to C5) in terms of hydrocarbons having 1 carbon atom (C1). It becomes very high at ppm or more. Methane is not adsorbed by the activated carbon, and hydrocarbons having 2 to 5 carbon atoms pass through the catalyst cylinder without being almost adsorbed by the activated carbon, so that the subsequent rectification load increases.

  Patent Document 4 does not disclose any oil contained in argon gas or removal of by-product hydrocarbons by decomposition of the oil.

  An object of the present invention is to provide an argon gas refining method and a refining apparatus that can solve the above-described problems of the prior art.

The method of the present invention is a method for purifying an argon gas containing at least oxygen, hydrogen, carbon monoxide, hydrocarbon, oil and nitrogen as impurities, wherein a part of the hydrocarbon and the oil in the argon gas are converted into activated carbon. Adsorb and then determine whether the amount of oxygen in the argon gas exceeds a set amount necessary to react with all of hydrogen, carbon monoxide, and hydrocarbons in the argon gas; When the amount of oxygen in the gas is less than or equal to the set amount, oxygen is added so as to exceed the set amount, and then carbon monoxide, hydrogen, and hydrocarbon in the argon gas are reacted with oxygen using a catalyst. This produces carbon dioxide and water with oxygen remaining, and then exceeds the set amount necessary to react with all of the oxygen remaining in the argon gas. Then, carbon monoxide is added, and then oxygen and carbon monoxide in the argon gas are reacted using a ruthenium catalyst, a palladium catalyst, or a mixed catalyst thereof, so that carbon monoxide remains. Then, carbon dioxide is produced in the state, and then at least carbon monoxide, carbon dioxide, water, and nitrogen in the argon gas are adsorbed on the adsorbent by a pressure swing adsorption method.
According to the present invention, the oil contained in the argon gas is adsorbed by the activated carbon, and some of the hydrocarbons derived from the oil are also adsorbed by the activated carbon. Particularly, hydrocarbons other than those having 1 to 5 carbon atoms are adsorbed by the activated carbon. Adsorbed effectively. Thereby, by reducing the amount of hydrocarbon in the argon gas, the amount of water and carbon dioxide produced by the subsequent reaction of hydrocarbon and oxygen can be reduced, and the subsequent adsorption load can be reduced. In addition, after reacting hydrogen, carbon monoxide, and hydrocarbons in argon gas with oxygen to produce carbon dioxide and water with excess oxygen remaining, new oxygen monoxide is removed to remove the residual oxygen. Carbon is added to produce carbon dioxide. By using a ruthenium catalyst, a palladium catalyst, or a mixed catalyst thereof as the reaction catalyst, hydrogen can be prevented from being generated by the reaction between water and carbon monoxide. Thereby, in the pretreatment stage of the adsorption treatment by the adsorption device, hydrogen that is difficult to remove by the adsorption treatment can be prevented from remaining in the argon gas, so that the argon gas can be purified with high purity. Furthermore, by reacting the residual oxygen with the added carbon monoxide, oxygen can be removed from the argon gas at the pretreatment stage of the adsorption treatment by the adsorption device, so that the purification load can be reduced.

  In the present invention, it is preferable to use palladium as the catalyst for reacting carbon monoxide, hydrogen, and hydrocarbon with oxygen in the argon gas. As a result, palladium has high heat resistance and high reactivity. Therefore, when the argon gas contains a large amount of lower hydrocarbons such as methane, the reaction is sufficiently performed by increasing the reaction temperature, and the hydrocarbons in the argon gas are effective. Can be reduced.

  In the present invention, X-type zeolite is preferably used as the adsorbent used for the pressure swing adsorption method. The use of X-type zeolite increases the adsorption effect of hydrocarbons as well as carbon monoxide, carbon dioxide, water and nitrogen. Therefore, even if hydrocarbons remain in the argon gas in the previous stage of the adsorption process by the adsorption device, the hydrocarbons can be effectively adsorbed by the adsorbent by the pressure swing adsorption method.

Alternatively, in the present invention, it is preferable to use activated alumina and X-type zeolite as the adsorbent used for the pressure swing adsorption method. By using activated alumina as the adsorbent, moisture and carbon dioxide can be adsorbed and desorbed, so that the adsorption effect of carbon monoxide, nitrogen and hydrocarbons by the X-type zeolite can be enhanced. That is, carbon dioxide is relatively difficult to desorb from the X-type zeolite and reduces the adsorption effect of the X-type zeolite. If the X-type zeolite charged in the PSA unit is increased in order to enhance the adsorption effect, there is a problem that the capacity of the pressurizing compressor and the like has to be increased, resulting in an increase in the size of the PSA unit and a decrease in efficiency. On the other hand, the adsorption effect of X-type zeolite can be enhanced by adsorbing carbon dioxide with activated alumina. Thereby, even if hydrocarbons remain in the argon gas in the stage before the adsorption process by the adsorption device, the hydrocarbons can be effectively adsorbed to the adsorbent by the pressure swing adsorption method without increasing the size of the PSA unit. In addition, since the adsorption effect of carbon monoxide and nitrogen by the pressure swing adsorption method can be enhanced, argon gas can be purified with low energy and high purity without using a TSA unit.
In this case, when the weight ratio of activated alumina to X-type zeolite is reduced, the adsorption breakthrough time of nitrogen and hydrocarbon is shortened, and when it is increased, the adsorption breakthrough time is lengthened. Preferably, the activated alumina and the X-type zeolite are arranged in layers, and the weight ratio of the activated alumina and the X-type zeolite is 5/95 to 30/70. Thereby, the hydrocarbon in the argon gas can be effectively adsorbed to the adsorbent by the pressure swing adsorption method. The activated alumina is preferably used for dehumidification and has a specific surface area of 270 m ² / g or more. As the X-type zeolite, for example, Li-X type and Ca-X type can be used, but Li-X type is preferable.

  In the present invention, after the adsorption by the pressure swing adsorption method, nitrogen in the argon gas is preferably adsorbed on the adsorbent by a thermal swing adsorption method at −10 ° C. to −50 ° C. The nitrogen concentration in the argon gas can be reduced only by adsorption using the pressure swing adsorption method, but by using the adsorption by the thermal swing adsorption method, the load on the PSA unit for performing the pressure swing adsorption method can be reduced and purified. Responding to the fluctuation of the impurity concentration in the previous argon gas, impurities can be removed reliably. Thereby, the purity of the argon gas after purification can be further increased. In addition, oxygen can be removed from the argon gas at the pretreatment stage of the adsorption treatment by the thermal swing adsorption method, and carbon monoxide can be removed by the pressure swing adsorption method, thereby reducing the cooling energy during the adsorption treatment by the thermal swing adsorption method. it can. In addition, hydrocarbons can be removed from the argon gas in the pretreatment stage of the thermal swing adsorption method, so it is necessary to desorb other than nitrogen during regeneration of the adsorbent used for the thermal swing adsorption method. There is no, and regenerative energy can be reduced.

The apparatus of the present invention is an apparatus for purifying argon gas containing at least oxygen, hydrogen, carbon monoxide, hydrocarbons, oil and nitrogen as impurities, the activated carbon adsorption tower into which the argon gas is introduced, and the activated carbon adsorption A first reactor into which argon gas flowing out from the tower is introduced, an oxygen supply device capable of adding oxygen to the argon gas introduced into the first reactor, and argon gas flowing out from the first reactor are introduced Second reactor, carbon monoxide supplier capable of adding carbon monoxide to the argon gas introduced into the second reactor, and adsorption device into which the argon gas flowing out from the second reactor is introduced The activated carbon adsorption tower contains activated carbon that adsorbs a part of hydrocarbons and oil in the argon gas, and the first reactor contains carbon monoxide in the argon gas. , Hydrogen, and a catalyst for reacting hydrocarbon with oxygen are accommodated, and the second reactor accommodates a ruthenium catalyst, a palladium catalyst for reacting oxygen and carbon monoxide in the argon gas, or a mixed catalyst thereof. The adsorption apparatus has a PSA unit that adsorbs at least carbon monoxide, carbon dioxide, water, and nitrogen in the argon gas by a pressure swing adsorption method. Furthermore, it is preferable that the adsorption device has a TSA unit that adsorbs nitrogen in the argon gas flowing out from the PSA unit by a thermal swing adsorption method at −10 ° C. to −50 ° C.
According to the apparatus of the present invention, the method of the present invention can be carried out.

  According to the present invention, by reducing the impurity content of argon gas at the pretreatment stage of the adsorption treatment, the load of the adsorption treatment is reduced, the energy required for purification is reduced, and the recovered argon gas is purified to a high purity. Furthermore, it is possible to provide a practical method and apparatus that can effectively cope with the case where the argon gas contains hydrocarbon and oil.

Arrangement explanatory drawing of the refiner | purifier of the argon gas which concerns on 1st Embodiment of this invention. Structure explanatory drawing of the PSA unit in the purification apparatus of argon gas concerning a 1st embodiment of the present invention Structure explanatory drawing of the TSA unit in the argon gas refiner | purifier which concerns on 1st Embodiment of this invention. Arrangement explanatory drawing of the refiner | purifier of the argon gas which concerns on 2nd Embodiment of this invention. Structure explanatory drawing of the PSA unit in the refiner | purifier of the argon gas which concerns on 2nd Embodiment of this invention.

  The argon gas purification apparatus α according to the first embodiment shown in FIG. 1 recovers and reuses spent argon gas supplied from an argon gas supply source 1 such as a single crystal silicon or polycrystalline silicon casting furnace. Purify for use. The purification apparatus α includes a filter 2, an activated carbon adsorption tower 3, a heater 4, a reaction apparatus 5 having a first reactor 5a and a second reactor 5b, a cooler 6, an adsorption apparatus 7, an oxygen supply apparatus 8, and carbon monoxide. A feeder 9 and a product tank T are provided.

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

  Argon gas supplied from the supply source 1 is collected by, for example, an oil rotary vacuum pump (not shown), and after being removed by a filter 2 (for example, AF1000P manufactured by CKD), is first introduced into the activated carbon adsorption tower 3. Activated carbon that adsorbs part of hydrocarbons and oil in argon gas is accommodated in the activated carbon adsorption tower 3.

The amount of oxygen in the argon gas after some of the hydrocarbons and oil are adsorbed on the activated carbon exceeds the set amount of oxygen required to react with all of the hydrogen, carbon monoxide, and hydrocarbons in the argon gas. It is determined whether or not. In this embodiment, the set amount of oxygen is the stoichiometric amount of oxygen necessary to react with all of hydrogen, carbon monoxide, and hydrocarbon in the argon gas.
Since the amount of oxygen required for complete combustion of the hydrocarbons differs depending on the type of hydrocarbons contained in the argon gas, the above determination was performed by previously determining the composition and concentration of the impurities contained in the argon gas. It is preferable to perform the above. For example, when the hydrocarbon contained in the argon gas is methane, the reaction formula in which hydrogen, carbon monoxide, and methane in the argon gas react with oxygen to produce water and carbon dioxide is as follows.
H ₂ +1/2 O ₂ → H ₂ O
CO + 1/2 O ₂ → CO ₂
CH ₄ + 2O ₂ → CO ₂ + 2H ₂ O
In this case, the oxygen concentration in the argon gas depends on whether the oxygen molar concentration in the argon gas exceeds a value equal to the sum of 1/2 the hydrogen molar concentration, 1/2 the carbon monoxide molar concentration and twice the methane molar concentration. What is necessary is just to determine whether the quantity exceeds the said stoichiometric quantity. Of course, the hydrocarbon contained in the argon gas is not limited to methane, and two or more kinds of hydrocarbons may be contained.
The set amount of oxygen does not have to be the stoichiometric amount, and may be more than the stoichiometric amount. For example, the value is preferably 1.05 to 2.0 times the stoichiometric amount, and 1.05 times or more ensures that the oxygen in the argon gas is hydrogen, carbon monoxide, and hydrocarbon. The oxygen concentration can be prevented from becoming unnecessarily high by setting it to 2.0 times or less.

When the amount of oxygen in the argon gas is less than or equal to the set amount, oxygen is added to the argon gas so as to exceed the set amount. When the amount of oxygen in the argon gas exceeds the set amount, it is not necessary to add oxygen. That is, the purification apparatus α of the present embodiment directly purifies the argon gas when the oxygen amount in the argon gas exceeds the set amount, and the set amount when the oxygen amount is equal to or less than the set amount. The argon gas after the oxygen is added so as to exceed is purified. By providing the oxygen supply device 8 capable of adding oxygen to the argon gas introduced into the first reactor 5a, when the oxygen amount in the argon gas is equal to or less than the set amount, the argon gas is set to exceed the set amount. Oxygen can be added.
The oxygen supply device 8 can be constituted by a device capable of adding oxygen at a flow rate corresponding to the flow rate of argon gas introduced into the first reactor 5a, such as a high-pressure oxygen container having a flow control valve. Before the oxygen supply, a sampling line for sampling the argon gas introduced into the first reactor 5a is provided, and an oxygen analyzer (for example, DE-- manufactured by GE Sensing & Inspection Technologies Co., Ltd.) is provided in the sampling line. 150ε), hydrogen analysis gas chromatography (for example, PDD manufactured by GLscience), carbon monoxide analyzer (for example, ZRE manufactured by Fuji Electric Systems), and total hydrocarbon analyzer (for example, FIA-510 manufactured by Horiba)
It is preferable to provide an oxygen analyzer in the sampling line for argon gas before flowing out from the first reactor 5a and being introduced into the second reactor 5b. Thereby, by monitoring the impurity composition in argon gas continuously, a slight excess of oxygen can be added more reliably.

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

  The first reactor is configured such that carbon monoxide, hydrogen, and hydrocarbons in the argon gas react with oxygen in the first reactor 5a so that carbon dioxide and water are generated in a state where oxygen remains. A catalyst is accommodated in 5a. The catalyst accommodated in the 1st reactor 5a will not be specifically limited if oxygen is made to react with carbon monoxide, hydrogen, and a hydrocarbon. For example, a catalyst in which platinum, platinum alloy, palladium, ruthenium, or a mixture thereof is supported on alumina can be used. When the argon gas contains a large amount of lower hydrocarbons such as methane, the reaction temperature is preferably set to 300 ° C. or higher so that the reaction proceeds sufficiently. Therefore, it is preferable to use a catalyst in which palladium having good heat resistance and high reactivity is supported on alumina. By using such a palladium catalyst, hydrocarbons in the argon gas can be effectively reduced in the first reactor 5a.

Argon gas flowing out from the first reactor 5a is introduced into the second reactor 5b. Carbon monoxide is added to the argon gas introduced into the second reactor 5b after flowing out of the first reactor 5a by the carbon monoxide supplier 9, and introduced into the second reactor 5b together with the argon gas. By the addition of carbon monoxide, the amount of carbon monoxide in the argon gas introduced into the second reactor 5b exceeds the set amount necessary to react with all of the oxygen remaining in the argon gas. The
In this embodiment, the set amount of carbon monoxide is the stoichiometric amount of carbon monoxide necessary to react with all of the oxygen in the argon gas. In this case, the carbon monoxide molar concentration in the argon gas exceeds twice the oxygen molar concentration measured at the outlet of the first reactor 5a, so that the carbon monoxide amount in the argon gas exceeds the stoichiometric amount.
The set amount of the carbon monoxide does not need to be the stoichiometric amount, and may be more than the stoichiometric amount. For example, the value is preferably 1.05 to 2.0 times the stoichiometric amount, and by making the value 1.05 times or more, the carbon monoxide in the argon gas is reliably reacted with the residual oxygen to remain. Oxygen can be consumed, and by making it 2.0 times or less, it is possible to prevent the residual carbon monoxide concentration from becoming higher than necessary.
The carbon monoxide feeder 9 is configured by a device capable of adding carbon monoxide at a flow rate corresponding to the flow rate of argon gas introduced into the second reactor 5b, such as a high-pressure carbon monoxide container having a flow rate control valve. it can. Before supplying the carbon monoxide, a sampling line for sampling the argon gas introduced into the second reactor 5b is provided, and an oxygen analyzer and a carbon monoxide analyzer are provided in the sampling line. It is preferable to provide a carbon monoxide analyzer in the sampling line of the argon gas before flowing out from the second reactor 5b and being introduced into the adsorption device 7. Thereby, by monitoring the impurity composition in argon gas continuously, a slight excess of carbon monoxide can be added more reliably.

  In the second reactor 5b, oxygen in the argon gas reacts with carbon monoxide, so that carbon dioxide is generated in a state in which carbon monoxide remains, so that the ruthenium catalyst, palladium is added to the second reactor 5b. A catalyst or a mixed catalyst thereof is accommodated. The ruthenium catalyst, palladium catalyst, or mixed catalyst thereof is preferably supported on alumina. The reaction temperature is preferably 80 ° C. or higher and 200 ° C. or lower. If it is less than 80 degreeC, the reactivity will fall, and even if it exceeds 200 degreeC, a suitable effect is not acquired but it is disadvantageous in terms of energy.

  The argon gas flowing out from the second reactor 5b is cooled by the cooler 6 and reaches the adsorption device 7 after moisture is reduced. The adsorption device 7 of this embodiment includes a PSA unit 10 and a TSA unit 20.

  The PSA unit 10 adsorbs at least carbon monoxide, carbon dioxide, water, and nitrogen in argon gas to the adsorbent by a pressure swing adsorption method at room temperature. The argon gas cooled by the cooler 6 is introduced into the PSA unit 10. Thereby, the carbon dioxide and water produced | generated in the 1st reactor 5a, the carbon dioxide produced | generated in the 2nd reactor 5b, and the residual carbon monoxide are PSA with the nitrogen originally contained in argon gas. It is adsorbed by the adsorbent in the unit 10. Further, when hydrocarbons remain in the argon gas introduced into the PSA unit 10, the hydrocarbons can be adsorbed.

As the PSA unit 10, a known unit can be used. For example, the PSA unit 10 shown in FIG. 2 is of a two-column type, has a compressor 12 for compressing argon gas, and first and second adsorption towers 13, and each adsorption tower 13 is filled with an adsorbent. The adsorbent is capable of adsorbing carbon monoxide, carbon dioxide, water, and nitrogen. In this embodiment, X-type zeolite is used to enhance the nitrogen adsorption effect, and in particular, Li-X type, Ca-X. A type of synthetic zeolite is preferred. Moreover, you may fill the lower part of each adsorption tower 13 with the alumina for dehydration as an adsorbent which raises a moisture adsorption effect.
Each of the inlets 13a of the adsorption tower 13 is connected to the raw material pipe 13f via the switching valve 13b, connected to the atmosphere via the switching valve 13c and the silencer 13e, and mutually connected via the switching valve 13d and the lower pressure equalizing pipe 13g. Connected. The argon gas flowing out of the second reactor 5b and cooled by the cooler 6 reaches the raw material pipe 13f after being compressed by the compressor 12.
Each of the outlets 13k of the adsorption tower 13 is connected to the outflow pipe 13o via the switching valve 13l, connected to the cleaning pipe 13p via the switching valve 13m, and connected to each other via the switching valve 13n and the upper pressure equalizing pipe 13q. The
The outflow pipe 13o is connected to the inlet of the pressure equalizing tank 14 through a check valve 13r and a switching valve 13s arranged in parallel. The outlet of the pressure equalizing tank 14 is connected to the inlet of the storage tank 15 via a pressure control valve 14 a for controlling the adsorption pressure in the adsorption tower 13. The outlet of the storage tank 15 is connected to the TSA unit 20 via an outlet pipe 15a. The outflow pipe 13o and the pressure equalizing tank 14 are connected to the cleaning pipe 13p via the flow control valve 13u and the flow rate indicating controller 13v, and the argon gas having a reduced impurity concentration flowing out from the adsorption tower 13 is supplied to the cleaning pipe. It is possible to adjust the flow rate to the adsorption tower 13 through 13p and send it again.

In each of the first and second adsorption towers 13 of the PSA unit 10, an adsorption process, a pressure equalizing process, a desorption process, a cleaning process, a pressure equalizing process, and a pressure increasing process are sequentially performed.
That is, by opening only the switching valves 13b and 13l in the first adsorption tower 13, the argon gas compressed by the compressor 12 is introduced into the first adsorption tower 13 through the switching valve 13b. The adsorption process is performed in the first adsorption tower 13 by adsorbing at least carbon monoxide, carbon dioxide, nitrogen, and moisture in the introduced argon gas to the adsorbent. The argon gas whose impurity content is reduced in the first adsorption tower 13 is sent to the pressure equalization tank 14 through the outflow pipe 13o. At this time, in the second adsorption tower 13, only the switching valves 13m and 13c are opened, so that a part of the argon gas sent from the first adsorption tower 13 to the outflow pipe 13o becomes the washing pipe 13p and the flow control valve 13u. Is sent to the second adsorption tower 13, and the second adsorption tower 13 undergoes a washing step.
Next, the switching valves 13b and 13l are closed in the first adsorption tower 13, the switching valves 13m and 13c are closed in the second adsorption tower 13, and the switching valves 13n and 13d are opened. In the second adsorption tower 13, a pressure equalization step for making the internal pressure uniform is performed.
Next, when the switching valves 13n and 13d are closed and the switching valve 13c is opened in the first adsorption tower 13, a desorption process for desorbing impurities from the adsorbent is performed in the first adsorption tower 13, and the desorbed impurities Is released into the atmosphere together with the gas through the silencer 13e. At this time, the switching valves 13b and 13l are opened in the second adsorption tower 13 and the switching valve 13s is opened, so that the argon gas compressed by the compressor 12 is introduced into the pressure equalizing tank 14 through the switching valve 13b. Is introduced through the switching valve 13s and the switching valve 13l, the pressure increasing process is performed in the second adsorption tower 13 and the adsorption process is started.
Next, the switching valve 13m is opened in the first adsorption tower 13 and the switching valve 13s is closed, whereby one of the argon gases sent from the second adsorption tower 13 where the adsorption process is being performed to the outflow pipe 13o. The part is sent to the first adsorption tower 13 through the washing pipe 13p and the flow rate control valve 13u, and the washing process is performed in the first adsorption tower 13. The gas used in the cleaning process is released into the atmosphere through the switching valve 13c and the silencer 13e.
Next, the switching valves 13c and 13m are closed in the first adsorption tower 13, the switching valves 13b and 13l are closed in the second adsorption tower 13, and the switching valves 13n and 13d are opened. In the second adsorption tower 13, a pressure equalization step for making the internal pressure uniform is performed.
Next, the switching valves 13 n and 13 d are closed, the switching valves 13 b and 13 l are opened in the first adsorption tower 13, and the switching valve 13 s is opened, whereby the argon gas compressed by the compressor 12 and the pressure equalizing tank 14 are opened. Argon gas with a reduced content of impurities in is introduced, a pressure increasing step is performed in the first adsorption tower 13 and an adsorption step is started. At this time, by opening the switching valve 13c in the second adsorption tower 13, a desorption process for desorbing impurities from the adsorbent is performed in the second adsorption tower 13, and the impurities are released into the atmosphere together with the gas through the silencer 13e. Is done.
The above steps are sequentially repeated in the first and second adsorption towers 13, respectively, so that the argon gas whose impurity content has been reduced passes through the pressure equalization tank 14, the pressure control valve 14a, the storage tank 15, and the outlet pipe 15a. To the TSA unit 20.
Note that the PSA unit 10 is not limited to that shown in FIG. 2, and the number of towers may be other than 2, for example, 3 or 4.

  Argon gas containing nitrogen that has not been adsorbed by 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 thermal swing adsorption method at −10 ° C. to −50 ° C.

A known TSA unit 20 can be used. For example, the TSA unit 20 shown in FIG. 3 is a two-column type, and a heat exchange type precooler 21 that precools the argon gas sent from the PSA unit 10 and heat that further cools the argon gas cooled by the precooler 21. The heat exchanger 24 that covers the exchange-type cooler 22, the first and second adsorption towers 23, and the respective adsorption towers 23 is provided. The heat exchanging unit 24 cools the adsorbent with a refrigerant during the adsorption process, and heats the adsorbent with a heat medium during the desorption process. Each adsorption tower 23 has a large number of inner tubes filled with an adsorbent. As the adsorbent, those suitable for adsorption of nitrogen are used. For example, it is preferable to use a zeolite-based adsorbent ion-exchanged with calcium (Ca) or lithium (Li), and an ion exchange rate of 70% or more. It is particularly preferable that the specific surface area be 600 m ² or more.
The cooler 22 is connected to the inlet 23a of each adsorption tower 23 via a switching valve 23b.
Each of the inlets 23a of the adsorption tower 23 communicates with the atmosphere via the switching valve 23c.
Each of the outlets 23e of the adsorption tower 23 is connected to an outflow pipe 23g through a switching valve 23f, connected to a cooling / pressure-increasing pipe 23i through a switching valve 23h, and connected to a cleaning pipe 23k through a switching valve 23j. Is done.
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 through the switching valve 23l.
The cooling / pressurizing piping 23i and the cleaning piping 23k are connected to the outflow piping 23g via a flow meter 23m, a flow control valve 23o, and a switching valve 23n.
The heat exchanging unit 24 is a multi-tube type, and includes an outer tube 24a surrounding a large number of inner tubes 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. Is done. In addition, the refrigerant supplied from the refrigerant supply source 24b is circulated through the outer pipe 24a and the refrigerant radiator 24c, and the heat medium supplied from the heat medium supply source 24d is supplied to the outer pipe 24a and the heat medium radiator 24e. A plurality of switching valves 24f are provided for switching to a state of circulation through the switching valves 24f. Further, a part of the cooler 22 is constituted by a pipe branched from the refrigerant radiator 24c, and the argon gas is cooled in the cooler 22 by the refrigerant supplied from the refrigerant supply source 24b, and the refrigerant is returned to the tank 24g. .

In each of the first and second adsorption towers 23 of the TSA unit 20, an adsorption process, a desorption process, a cleaning process, a cooling process, and a pressure increasing process are sequentially performed.
That is, 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 circulating the refrigerant in the heat exchanger 24, the switching valves 23c, 23h, and 23j are closed, and the switching valve 23f is opened. In addition, at least nitrogen contained in the argon gas is adsorbed by the adsorbent. As a result, an adsorption step is performed in the first adsorption tower 23, and purified argon gas with reduced impurity content flows out from the adsorption tower 23 through the switching valve 23 l and is sent to the product tank T.
While the adsorption process is performed in the first adsorption tower 23, the desorption process, the cleaning process, the cooling process, and the pressure increasing process are performed in the second adsorption tower 23.
That is, in the second adsorption tower 23, the switching valves 23b and 23f are closed and the switching valve 23c is opened to perform the desorption process after the adsorption process is completed. Thereby, in the 2nd adsorption tower 23, argon gas containing an impurity is discharge | released in air | atmosphere, and a pressure is reduced to substantially atmospheric pressure. In this desorption process, the switching valve 24f of the heat exchanging section 24 that has circulated the refrigerant in the second adsorption tower 23 during the adsorption process is switched to the closed state to stop the circulation of the refrigerant, and the refrigerant is extracted from the heat exchanging section 24. The switching valve 24f that returns to the refrigerant supply source 24b is switched to the open state.
Next, in order to carry out the cleaning process in the second adsorption tower 23, the switching valves 23c, 23j of the second adsorption tower 23 and the switching valve 23n of the cleaning pipe 23k are opened, and the heat in the heat exchange type precooler 21 is heated. Part of the purified argon gas heated by the exchange is introduced into the second adsorption tower 23 through the cleaning pipe 23k. Thus, in the second adsorption tower 23, desorption of impurities from the adsorbent and cleaning with purified argon gas are performed, and the argon gas used for the cleaning is released into the atmosphere together with the impurities from the switching valve 23c. In this cleaning step, the switching valve 24f of the heat exchange unit 24 for circulating the heat medium in the second adsorption tower 23 is switched to the open state.
Next, in order to perform the cooling process in the second adsorption tower 23, the switching valve 23j of the second adsorption tower 23 and the switching valve 23n of the cleaning pipe 23k are closed, and the switching valve 23h of the second adsorption tower 23 The switching valve 23n of the cooling / pressurizing pipe 23i is opened, and a part of the purified argon gas flowing out from the first adsorption tower 23 is introduced into the second adsorption tower 23 through the cooling / pressurizing pipe 23i. As a result, the purified argon gas cooled in the second adsorption tower 23 is released into the atmosphere through the switching valve 23c. In this cooling process, the switching valve 24f for circulating the heat medium is switched to the closed state to stop the circulation of the heat medium, and the switching valve 24f that extracts the heat medium from the heat exchange unit 24 and returns it to the heat medium supply source 24d is provided. Switch to the open state. After completion of the extraction of the heat medium, the switching valve 24f of the heat exchanging unit 24 for circulating the refrigerant in the second adsorption tower 23 is switched to the open state to set the refrigerant circulation state. This refrigerant circulation state continues until the end of the next pressurization step and the subsequent adsorption step.
Next, in order to perform the pressure increasing process 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. The inside of the two adsorption tower 23 is pressurized. This pressure increasing process is continued 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 process is completed, the switching valve 23h of the second adsorption tower 23 and the switching valve 23n of the cooling / pressure increasing pipe 23i are closed, whereby all the switching valves 23b, 23c, 23f, 23h of the second adsorption tower 23 are closed. , 23j are closed, and the second adsorption tower 23 is in a standby state until the next adsorption step.
The adsorption process of the second adsorption tower 23 is performed in the same manner as the adsorption process of the first adsorption tower 23. While the adsorption process is performed in the second adsorption tower 23, the desorption process, the washing process, the cooling process, and the pressure increasing process are performed in the first adsorption tower 23 in the same manner as in the second adsorption tower 23.
The TSA unit 20 is not limited to the one shown in FIG. 3, and the number of towers may be 2 or more, for example, 3 or 4.

  4 and 5 show an argon gas purification apparatus α according to a second embodiment of the present invention. The difference of the second embodiment from the first embodiment is the configuration of the adsorption device 7. That is, as shown in FIG. 4, the adsorption device 7 of the second embodiment includes a PSA unit 10 'but does not include a TSA unit. The PSA unit 10 'adsorbs at least carbon monoxide, carbon dioxide, water, and nitrogen in argon gas to the adsorbent by a pressure swing adsorption method at room temperature. The argon gas cooled by the cooler 6 is introduced into the PSA unit 10 '. Thereby, the carbon dioxide and water produced | generated in the 1st reactor 5a, the carbon dioxide produced | generated in the 2nd reactor 5b, and the residual carbon monoxide are PSA with the nitrogen originally contained in argon gas. It is adsorbed by the adsorbent in the unit 10 '. Moreover, when a hydrocarbon remains in the argon gas introduced into PSA unit 10 ', the hydrocarbon can also be adsorbed. The PSA unit 10 'of the second embodiment has a configuration different from that of the PSA unit 10 of the first embodiment.

A known PSA unit 10 'can be used. For example, the PSA unit 10 ′ shown in FIG. 5 is a four-column type, and has a compressor 12 ′ that compresses argon gas flowing out from the second reactor 5b, and four first to fourth adsorption columns 13 ′. Each adsorption tower 13 'is filled with an adsorbent. The adsorbent is capable of adsorbing carbon monoxide, carbon dioxide, water, and nitrogen. In this embodiment, activated alumina and X-type zeolite are used. As the X-type zeolite, Li-X type and Ca- X-type synthetic zeolite is preferred. The arrangement of the activated alumina and the X-type zeolite in each adsorption tower 13 'is not particularly limited. For example, the activated alumina and the X-type zeolite may be arranged alternately in layers. The weight ratio of activated alumina to X-type zeolite is preferably 5/95 to 30/70. When the two layers are alternately arranged, it is preferable to arrange activated alumina upstream of the argon gas flow and arrange X-type zeolite downstream.
The compressor 12 'is connected to the inlet 13a' of each adsorption tower 13 'via a switching valve 13b'.
Each inlet 13a ′ of the adsorption tower 13 ′ is connected to the atmosphere via a switching valve 13e ′ and a silencer 13f ′.
Each of the outlets 13k ′ of the adsorption tower 13 ′ is connected to an outflow pipe 13m ′ via a switching valve 13l ′, connected to a boosting pipe 13o ′ via a switching valve 13n ′, and equalized via a switching valve 13p ′. -It is connected to the washing outlet side pipe 13q 'and is connected to the pressure equalization / washing inlet side pipe 13s' via the switching valve 13r'.
The outflow pipe 13m ′ is connected to the product tank T via a pressure control valve 13t ′.
The booster pipe 13o ′ is connected to the outflow pipe 13m ′ via the flow rate control valve 13u ′ and the flow rate indicating controller 13v ′, and is introduced into the product tank T by adjusting the flow rate in the booster pipe 13o ′ to be constant. The flow rate variation of the argon gas is prevented.
The pressure equalizing / cleaning outlet side pipe 13q ′ and the pressure equalizing / cleaning inlet side pipe 13s ′ are connected to each other via a pair of connecting pipes 13w ′, and a switching valve 13x ′ is provided in each connecting pipe 13w ′.

In each of the first to fourth adsorption towers 13 ′ of the PSA unit 10 ′, an adsorption process, a reduced pressure I process (cleaning gas discharge process), a reduced pressure II process (equal pressure gas discharge process), a desorption process, and a cleaning process (cleaning gas input) Step), step-up I step (equal pressure gas injection step), step-up II step are sequentially performed. Each process is demonstrated as follows on the basis of 1st adsorption tower 13 '.
That is, 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 supplied from the compressor 12' via the switching valve 13b 'to the first adsorption. It is introduced into the tower 13 '. As a result, at least nitrogen, carbon monoxide, carbon dioxide, and moisture in the argon gas introduced in the first adsorption tower 13 ′ are adsorbed by the adsorbent, so that the adsorption process is performed and the impurity content is reduced. The argon gas is sent from the first adsorption tower 13 'to the product tank T through the outflow pipe 13m'. At this time, a part of the argon gas sent to the outflow pipe 13m ′ is sent to another adsorption tower (second adsorption tower 13 ′ in the present embodiment) via the boosting pipe 13o ′ and the flow rate control valve 13u ′. In the second adsorption tower 13 ', the pressure increase II process is performed.
Next, the switching valves 13b 'and 13l' of the first adsorption tower 13 'are closed, the switching valve 13p' is opened, and the switching valve 13r 'of another adsorption tower (the fourth adsorption tower 13' in this embodiment) is opened. Open one of the switching valves 13x '. As a result, the argon gas having a relatively small impurity content at the top of the first adsorption tower 13 ′ is sent to the fourth adsorption tower 13 ′ via the pressure equalization / cleaning inlet side pipe 13 s ′. In step ′, a reduced pressure I step is performed. At this time, in the fourth adsorption tower 13 ′, the switching valve 13e ′ is opened, and the cleaning process is performed.
Next, the switching valve 13e 'of the fourth adsorption tower 13' is closed while the switching valve 13p 'of the first adsorption tower 13' and the switching valve 13r 'of the fourth adsorption tower 13' are opened. As a result, the decompression II step is performed in which the fourth adsorption tower 13 ′ recovers the gas until the internal pressures of the first adsorption tower 13 ′ and the fourth adsorption tower 13 ′ become uniform or substantially uniform. At this time, the two switching valves 13x ′ may be opened depending on circumstances.
Next, a desorption process for desorbing impurities from the adsorbent is performed by opening the switching valve 13e 'of the first adsorption tower 13' and closing the switching valve 13p ', and the impurities are released into the atmosphere together with the gas through the silencer 13f'. Released into.
Next, the switching valve 13r ′ of the first adsorption tower 13 ′ is opened, the switching valves 13b ′ and 13l ′ of the second adsorption tower 13 ′ after the adsorption process is closed, and the switching valve 13p ′ is opened. As a result, the argon gas having a relatively small impurity content at the upper part of the second adsorption tower 13 ′ is sent to the first adsorption tower 13 ′ via the pressure equalization / cleaning inlet side pipe 13 s ′. A cleaning step is performed at ′. The gas used in the cleaning process in the first adsorption tower 13 ′ is released into the atmosphere via the switching valve 13e ′ and the silencer 13f ′. At this time, the reduced pressure I step is performed in the second adsorption tower 13 '.
Next, while the switching valve 13p 'of the second adsorption tower 13' and the switching valve 13r 'of the first adsorption tower 13' are open, the switching valve 13e 'of the first adsorption tower 13' is closed to perform the pressure increase I process. Is called. At this time, the two switching valves 13x ′ may be opened depending on circumstances.
Thereafter, the switching valve 13r ′ of the first adsorption tower 13 ′ is closed. Thereby, it will be in the standby state without a process once. This state continues until the step-up II process of the fourth adsorption tower 13 'is completed. When the pressurization of the fourth adsorption tower 13 'is completed and the adsorption process is switched from the third adsorption tower 13' to the fourth adsorption tower 13 ', the first adsorption tower switching valve 13n' is opened. As a result, a part of the argon gas sent from the other adsorption tower (fourth adsorption tower 13 'in the present embodiment) in the adsorption process to the outflow pipe 13m' passes through the pressure-up pipe 13o 'and the flow rate control valve 13u'. Then, the pressure II process is performed in the first adsorption tower 13 ′ by being sent to the first adsorption tower 13 ′.
The above steps are sequentially repeated in each of the first to fourth adsorption towers 13 ′, whereby argon gas with a reduced impurity content is continuously sent to the product tank T.
The PSA unit 10 'is not limited to that shown in FIG. 5, and the number of towers may be other than 4, for example, 2 or 3.
Other configurations in the second embodiment are the same as those in the first embodiment.

According to the purification apparatus α of the first embodiment and the second embodiment, when the argon gas containing at least oxygen, hydrogen, carbon monoxide, hydrocarbon, oil, and nitrogen as impurities is recovered and purified, The oil contained in the gas can be adsorbed by activated carbon, and some of the hydrocarbons derived from the oil can also be adsorbed by activated carbon, and in particular, hydrocarbons other than those having 1 to 5 carbon atoms can be effectively adsorbed by activated carbon. Next, it is determined whether or not the amount of oxygen in the argon gas exceeds the set amount of oxygen necessary to react with all of hydrogen, carbon monoxide, and hydrocarbons in the argon gas, and the amount of oxygen is determined as described above. When the amount is less than the amount, oxygen is added so as to exceed the set amount. Thereafter, carbon monoxide, hydrogen, and hydrocarbon in argon gas are reacted with oxygen using a catalyst, so that carbon dioxide and water can be generated with oxygen remaining. Thereby, main impurities in the argon gas are carbon dioxide, water, oxygen, and nitrogen. Next, carbon monoxide is added so that the amount of carbon monoxide in the argon gas exceeds the set amount necessary to react with all of the remaining oxygen. Thereafter, oxygen and carbon monoxide in the argon gas are reacted with each other using a ruthenium catalyst, a palladium catalyst, or a mixed catalyst thereof, whereby carbon dioxide can be generated with carbon monoxide remaining. Thereby, main impurities in the argon gas are water, carbon monoxide, carbon dioxide, and nitrogen. Here, by using a ruthenium catalyst, a palladium catalyst, or a mixed catalyst thereof as a catalyst for reacting oxygen and carbon monoxide in argon gas, hydrogen can be prevented from being generated due to the reaction between water and carbon monoxide. Next, carbon monoxide, carbon dioxide, water, and nitrogen in the argon gas can be adsorbed on the adsorbent by the pressure swing adsorption method.
That is, by effectively adsorbing hydrocarbons having an oil content and a carbon number other than 1 to 5 with activated carbon, the amount of hydrocarbons in the argon gas is reduced, and thus produced by the subsequent reaction between hydrocarbons and oxygen. It is possible to reduce the amount of water and carbon dioxide and to reduce the adsorption load in the subsequent adsorption device 7. Further, since it is possible to prevent hydrogen that is difficult to be removed by the adsorption treatment by the adsorption device 7 from remaining in the argon gas, the argon gas can be purified with high purity. Furthermore, 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. Further, by using X-type zeolite as the adsorbent used for the pressure swing adsorption method, not only carbon monoxide, carbon dioxide, water, and nitrogen, but also a hydrocarbon adsorption effect is enhanced. Therefore, even if hydrocarbons remain in the argon gas in the previous stage of the adsorption process by the adsorption device 7, the hydrocarbons in the argon gas can be effectively adsorbed by the adsorbent by the pressure swing adsorption method.

  According to the purification apparatus α of the first embodiment, after adsorption by the pressure swing adsorption method, nitrogen in the argon gas can be adsorbed to the adsorbent by a thermal swing adsorption method at −10 ° C. to −50 ° C. . Thus, by using the adsorption by the thermal swing adsorption method together, the load on the PSA unit 10 can be reduced, and the impurities can be reliably removed in response to the fluctuation of the impurity concentration in the argon gas before purification. Therefore, the purity of the argon gas after purification can be further increased. In addition, oxygen can be removed from the argon gas at the pretreatment stage of the adsorption treatment by the thermal swing adsorption method, and carbon monoxide can be removed by the pressure swing adsorption method, thereby reducing the cooling energy during the adsorption treatment by the thermal swing adsorption method. it can. In addition, hydrocarbons can be removed from the argon gas in the pretreatment stage of the thermal swing adsorption method, so it is necessary to desorb other than nitrogen during regeneration of the adsorbent used for the thermal swing adsorption method. There is no, and regenerative energy can be reduced. Moreover, since the adsorption effect of nitrogen can be enhanced by using X-type zeolite as the adsorbent in the PSA unit 10, the adsorption load of nitrogen in the TSA unit 20 is reduced, and the recovered argon gas is purified to a higher purity. it can.

  According to the purification apparatus α of the second embodiment, by using activated alumina and X-type zeolite as adsorbents in the PSA unit 10 ', moisture and carbon dioxide are adsorbed and desorbed in argon gas with activated alumina. The adsorption effect of carbon monoxide, nitrogen and hydrocarbons by the X-type zeolite can be enhanced. Thereby, even if hydrocarbons remain in the argon gas in the previous stage of the adsorption process by the adsorption device 7, the hydrocarbons are effectively adsorbed by the adsorbent by the pressure swing adsorption method without increasing the size of the PSA unit 10 '. be able to. In addition, since the adsorption effect of carbon monoxide and nitrogen by the pressure swing adsorption method can be enhanced, argon gas can be purified with low energy and high purity without using a TSA unit.

The argon gas was purified using the purification apparatus α of the first embodiment. Before purification, the argon gas contains 300 molppm of oxygen, 30 molppm of hydrogen, 200 molppm of carbon monoxide, 1200 molppm of nitrogen, 10 molppm of carbon dioxide, 10 molppm of water, and hydrocarbon as impurities. 10 mol ppm of methane, 20 mol ppm of C2-C5 hydrocarbon in terms of C1 hydrocarbon, and 5 g / m ^{3 of} oil were contained. This argon gas was introduced into the activated carbon adsorption tower 3 at a flow rate of 4.2 L / min in a standard state. The activated carbon adsorption tower 3 was made into a pipe shape with a nominal diameter of 32A and filled with 10 L of GX6 / 8 cast charcoal manufactured by Nippon Envirochemicals. Next, argon gas was introduced into the first reactor 5a. In the first reactor 5a, 50 mL of an alumina-supported palladium catalyst (DASH-220D manufactured by NE Chemcat) was charged, and the reaction conditions were a temperature of 350 ° C., an atmospheric pressure, and a space velocity of 5000 / h. In this case, oxygen in the argon gas is contained about 1.8 times the theoretical value required to react with hydrogen, carbon monoxide, and hydrocarbons. Carbon monoxide was added from the carbon monoxide supplier 9 at a flow rate of 1.0 ml / min to the argon gas flowing out from the first reactor 5a and introduced into the second reactor 5b. In this case, carbon monoxide in the argon gas is contained about 1.2 times the theoretical value necessary for consuming residual oxygen. In the second reactor 5b, 50 ml of an alumina-supported ruthenium catalyst (RUA manufactured by Sued Chemie) was charged, and the reaction conditions were a temperature of 150 ° C., an atmospheric pressure, and a space velocity of 5000 / h.
The argon gas flowing out from the second reactor 5 b was cooled, and the impurity content was reduced by the adsorption device 7. The PSA unit 10 was of a two-column type, each column was in the shape of a pipe having a nominal diameter of 32A and a length of 1 m, and each column was packed with Li-X zeolite (Tosoh NSA-700) as an adsorbent. The operating conditions of the PSA unit 10 were an adsorption pressure of 0.8 MPaG, a desorption pressure of 10 kPaG, a cycle time of 400 sec / column, and a pressure equalization of 15 sec. The TSA unit 20 is of a two-column type, and each column is filled with 1.25 L of Ca-X zeolite (Mizusawa Chemical 812B) as an adsorbent, the adsorption pressure is 0.8 MPaG, the adsorption temperature is -35 ° C, and the desorption pressure is The pressure was 0.1 MPaG and the desorption temperature was 40 ° C.
In this case, the impurity composition of the argon gas at 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 was as shown in Table 1 below. The composition of hydrocarbons in Table 1 represents the sum of the methane concentration and the C1-hydrocarbon equivalent concentration of C2-C5 hydrocarbons.
The composition of the argon gas at the outlet of the activated carbon adsorption tower 3 was as follows.
Activated carbon adsorption tower outlet Hydrogen: 30 mol ppm, oxygen: 300 mol ppm, nitrogen: 1200 mol ppm, carbon monoxide: 200 mol ppm, carbon dioxide: 10 mol ppm, methane: 10 mol ppm, C2-C5 hydrocarbon: C1 hydrocarbon conversion 15 mol ppm, moisture: 10 mol ppm, oil: not detected Note that the oxygen concentration was measured by Delta F's micro oximeter model DF-150E, and the concentrations of carbon monoxide and carbon dioxide were Shimadzu Measured using a GC-FID manufactured by Seisakusho through a methanizer, the hydrogen concentration measured by GC-PDD manufactured by GLscience, the nitrogen concentration measured by a trace nitrogen analyzer manufactured by Round Science, and the hydrocarbon concentration measured by Shimadzu Measured with a GC-FID made by GC, and the oil content was calculated from the increase in the filtering amount of CKD filter VFA1000. Measurement was made using a point meter.

The oxygen concentration of the argon gas used for the purification was 50 mol ppm and the nitrogen concentration was 200 ppm, and oxygen was added to the argon gas from the oxygen supply device 8 at 1.1 ml / min before the first reactor 5a (thereby Is about 1.4 times the theoretical value required to react with hydrogen, carbon monoxide, and hydrocarbons). Otherwise, argon gas was purified under the same conditions as in Example 1.
The impurity composition of argon gas at the outlet of the activated carbon adsorption tower 3 and the outlet of the TSA unit 20 in this case was as follows.
Activated carbon adsorption tower outlet Hydrogen: 30 mol ppm, oxygen: 50 mol ppm, nitrogen: 200 mol ppm, carbon monoxide: 200 mol ppm, carbon dioxide: 10 mol ppm, moisture: 10 mol ppm, methane: 10 mol ppm, C2-C5 hydrocarbon: 15 mol ppm in terms of C1 hydrocarbon, oil: not detected.
-TSA unit outlet Hydrogen: Less than 0.1 mol ppm, Oxygen: 0.3 mol ppm, Nitrogen: less than 1 mol ppm, Carbon monoxide: less than 1 mol ppm, Carbon dioxide: less than 1 mol ppm, Hydrocarbon: 0.0. Less than 1 mol ppm, moisture: less than 1 mol ppm.

The catalyst used in the second reactor 5b was palladium on alumina. Otherwise, argon gas was purified under the same conditions as in Example 1.
In this case, the impurity composition of argon gas at 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 was as shown in Table 1.

The catalyst used in the first reactor 5a was platinum carrying alumina (DASH-220 manufactured by NE Chemcat). Otherwise, argon gas was purified under the same conditions as in Example 1.
In this case, the impurity composition of argon gas at 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 was as shown in Table 1.

Comparative Example 1

The catalyst used in the second reactor 5b was platinum carrying alumina. Otherwise, argon gas was purified under the same conditions as in Example 1.
In this case, the impurity composition of argon gas at 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 was as shown in Table 1.

Argon gas was purified using the purification apparatus α of the second embodiment. Before purification, the argon gas contains 300 molppm of oxygen, 30 molppm of hydrogen, 200 molppm of carbon monoxide, 1200 molppm of nitrogen, 10 molppm of carbon dioxide, 10 molppm of water, and hydrocarbon as impurities. 10 mol ppm of methane, 20 mol ppm of C2-C5 hydrocarbon in terms of C1 hydrocarbon, and 5 g / m ^{3 of} oil were contained. This argon gas was introduced into the activated carbon adsorption tower 3 at a flow rate of 4.2 L / min in a standard state. The activated carbon adsorption tower 3 was made into a pipe shape with a nominal diameter of 32A and filled with 10 L of GX6 / 8 cast charcoal manufactured by Nippon Envirochemicals. Next, argon gas was introduced into the first reactor 5a. In the first reactor 5a, 50 mL of an alumina-supported palladium catalyst (DASH-220D manufactured by NE Chemcat) was charged, and the reaction conditions were a temperature of 350 ° C., an atmospheric pressure, and a space velocity of 5000 / h. In this case, oxygen in the argon gas is contained about 1.8 times the theoretical value required to react with hydrogen, carbon monoxide, and hydrocarbons. Carbon monoxide was added from the carbon monoxide supplier 9 at a flow rate of 1.0 ml / min to the argon gas flowing out from the first reactor 5a and introduced into the second reactor 5b. In this case, carbon monoxide in the argon gas is contained about 1.2 times the theoretical value necessary for consuming residual oxygen. In the second reactor 5b, 50 ml of an alumina-supported ruthenium catalyst (RUA manufactured by Zude Chemie) was charged, and the reaction conditions were a temperature of 150 ° C., an atmospheric pressure, and a space velocity of 5000 / h.
The argon gas flowing out from the second reactor 5 b was cooled, and the impurity content was reduced by the adsorption device 7. The PSA unit 10 'is of a four-column type, each column is in the shape of a pipe having a nominal diameter of 32A and a length of 1 m, and 10 wt% of activated alumina (KHD-24 manufactured by Sumitomo Chemical) is used as an adsorbent in each column. (Tosoh NSA-700) was filled at 90 wt%. The operating conditions of the PSA unit 10 ′ were an adsorption pressure of 0.8 MPaG, a desorption pressure of 10 kPaG, a cycle time of 450 sec / column, and a pressure equalization of 15 sec.
In this case, the impurity composition of the argon gas at the outlet of the first reactor 5a, the outlet of the second reactor 5b, and the outlet of the PSA unit 10 'was as shown in Table 2 below. The composition of hydrocarbons in Table 2 represents the sum of the methane concentration and the C1-hydrocarbon equivalent concentration of C2-C5 hydrocarbons.
The composition of the argon gas at the outlet of the activated carbon adsorption tower 3 was as follows.
Activated carbon adsorption tower outlet Hydrogen: 30 mol ppm, oxygen: 300 mol ppm, nitrogen: 1200 mol ppm, carbon monoxide: 200 mol ppm, carbon dioxide: 10 mol ppm, methane: 10 mol ppm, C2-C5 hydrocarbon: C1 hydrocarbon conversion 15 mol ppm, moisture: 10 mol ppm, oil content: not detected Note that the oxygen concentration in the purified argon gas was measured by carbon monoxide and carbon dioxide using a trace oxygen analyzer DF-150E manufactured by Delta F. The concentration of carbon was measured through a metanizer using GC-FID manufactured by Shimadzu Corporation. For the hydrogen concentration, GC-PDD made by GLscience, the nitrogen concentration is a trace nitrogen analyzer made by Round Science, the hydrocarbon concentration is GC-FID made by Shimadzu, and the oil content is calculated from the increased amount of filtering by the filter VFA1000 made by CKD. Was measured using a dew point meter.

The catalyst used in the second reactor 5b was palladium on alumina. Otherwise, the argon gas was purified under the same conditions as in Example 5.
The impurity composition of the argon gas at the outlet of the first reactor 5a, the outlet of the second reactor 5b, and the outlet of the PSA unit 10 ′ in this case was as shown in Table 2.

The argon gas before purification in this example contains a carbon dioxide concentration of 1 mol%, and the contents of other impurities are the same as in example 5. Further, 30 wt% of activated alumina and 70 wt% of Li—X type zeolite as adsorbents were packed in each adsorption tower of the PSA unit 10 ′. Otherwise, the argon gas was purified under the same conditions as in Example 5.
The impurity composition of the argon gas at the outlet of the first reactor 5a, the outlet of the second reactor 5b, and the outlet of the PSA unit 10 ′ in this case was as shown in Table 2.

The catalyst used in the first reactor 5 a was platinum carrying alumina (DASH-220 manufactured by NE Chemcat), and the cycle time as the operating condition of the PSA unit 10 ′ was changed to 430 sec / column. Otherwise, the argon gas was purified under the same conditions as in Example 5.
The impurity composition of the argon gas at the outlet of the first reactor 5a, the outlet of the second reactor 5b, and the outlet of the PSA unit 10 ′ in this case was as shown in Table 2.

The catalyst used in the first reactor 5a was an alumina-supported ruthenium catalyst (RUA manufactured by Zude Chemie), and the cycle time, which is the operating condition of the PSA unit 10 ', was changed to 430 sec / tower. Otherwise, the argon gas was purified under the same conditions as in Example 5.
The impurity composition of the argon gas at the outlet of the first reactor 5a, the outlet of the second reactor 5b, and the outlet of the PSA unit 10 ′ in this case was as shown in Table 1.

Comparative Example 2

The catalyst used in the second reactor 5b is platinum carrying alumina, the adsorbent packed in each adsorption tower of the PSA unit 10 'is Li-X zeolite 100wt%, and the cycle time which is the operating condition of the PSA unit 10'. Was changed to 400 sec / tower. Otherwise, the argon gas was purified under the same conditions as in Example 5.
The impurity composition of the argon gas at the outlet of the first reactor 5a, the outlet of the second reactor 5b, and the outlet of the PSA unit 10 ′ in this case was as shown in Table 2.

Comparative Example 3

Without performing the pretreatment of the adsorption treatment, the argon gas was purified only by the adsorption treatment using the PSA unit 10 'and the TSA unit 20. The argon gas before purification contained 5000 molppm of carbon monoxide, 5000 molppm of nitrogen and 1 mol% of carbon dioxide as impurities. The PSA unit 10 'is of a four-column type, each column is in the shape of a pipe having a nominal diameter of 32A and a length of 1m, and 10% by weight of activated alumina (KHD-24 manufactured by Sumitomo Chemical Co.) is used as an adsorbent in each column. 90 wt% of (UOP 5A-HP) was filled. The operating conditions of the PSA unit 10 ′ were an adsorption pressure of 0.8 MPaG, a desorption pressure of 10 kPaG, a cycle time of 710 sec / column, and the argon gas was purified under the conditions of a uniform pressure of 15 sec. The TSA unit 20 is of a two-column type, and each column is filled with 1.25 L of Ca-X zeolite (Mizusawa Chemical 812B) as an adsorbent, the adsorption pressure is 0.8 MPaG, the adsorption temperature is -35 ° C, and the desorption pressure is The pressure was 0.1 MPaG and the desorption temperature was 40 ° C.
The impurity composition of argon gas at the outlet of the PSA unit 10 ′ and the outlet of the TSA unit 20 in this case was as 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

Each adsorption tower of the PSA unit 10 ′ is filled with 10 wt% activated alumina (KHD-24 manufactured by Sumitomo Chemical) and 90 wt% Li-X zeolite (NSA-700 manufactured by Tosoh Corporation) as an adsorbent, and the cycle time is 1000 sec / column. It was. Otherwise, argon gas was purified under the same conditions as in Comparative Example 3.
The impurity composition of argon gas at the outlet of the PSA unit 10 ′ and the outlet of the TSA unit 20 in this case was as 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

Each adsorption tower of the PSA unit 10 ′ is filled with 10 wt% activated alumina (KHD-24 manufactured by Sumitomo Chemical) and 90 wt% Li-X zeolite (NSA-700 manufactured by Tosoh Corporation) as an adsorbent, and the cycle time is 770 sec / column. It was. Otherwise, argon gas was purified under the same conditions as in Comparative Example 3.
The impurity composition of argon gas at the outlet of the PSA unit 10 ′ and the outlet of the TSA unit 20 in this case was as shown in Table 3. Further, the recovery rate of argon gas at the outlet of the PSA unit 10 ′ was 69%.

The following points can be confirmed from the respective examples and comparative examples.
It can be confirmed that hydrocarbons can be effectively reacted by using a palladium catalyst in the first reactor 5a, and that hydrogen can be prevented from being generated by using a ruthenium catalyst or a palladium catalyst in the second reactor 5b.
It can be confirmed that hydrocarbons can be effectively adsorbed by using X-type zeolite as the adsorbent used for the pressure swing adsorption method.
Also in Examples 5 to 9 that do not use the TSA unit, it can be confirmed that the nitrogen concentration of the argon gas is sufficiently reduced, and the recovered argon gas can be purified with high purity. Moreover, according to Examples 1-4 using the TSA unit 20, it can confirm that the nitrogen concentration of argon gas is reduced more.
The nitrogen concentration of argon gas at the outlet of the PSA unit 10 ′ in Comparative Example 5 is lower than the nitrogen concentration of argon gas at the outlet of the PSA unit 10 ′ in Comparative Example 4; Since the cycle time is short, a large amount of argon gas is discarded, and the recovery rate of argon gas decreases. 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 is similarly reduced. Therefore, it can be confirmed that the load on the PSA unit can be reduced by using the TSA unit together.
In Example 7, where the ratio of activated alumina to X-type zeolite in the PSA unit 10 ′ is higher than in Examples 5 and 6, the carbon dioxide concentration in the argon gas before purification is higher than in Examples 5 and 6, but As in Examples 5 and 6, the impurity concentration is reduced. From this, it can be confirmed that the use of activated alumina can adsorb and desorb moisture and carbon dioxide, and can maintain a high adsorption effect of carbon monoxide, nitrogen and hydrocarbons by the X-type zeolite.
From Comparative Examples 3 and 5, when the adsorbent used for the pressure swing adsorption method is Li-X type zeolite, the nitrogen concentration of the argon gas after purification can be reduced as compared with the case of using Ca-A type zeolite. Can be confirmed. Further, it can be confirmed from Comparative Examples 4 and 5 that the nitrogen concentration of the argon gas can be sufficiently reduced even when purification is performed only by the adsorption treatment.

  The present invention is not limited to the above-described embodiments and examples. For example, equipment used for the recovery of argon gas is not limited to equipment using oil such as an oil rotary vacuum pump, and for example, an oilless vacuum pump may be used.

  α ... purification device, 3 ... activated carbon adsorption tower, 5a ... first reactor, 5b ... second reactor, 7 ... adsorption device, 8 ... oxygen feeder, 9 ... carbon monoxide feeder, 10, 10 '... PSA Unit, 20 ... TSA unit, T ... Product tank

Claims (8)

A method for purifying argon gas containing at least oxygen, hydrogen, carbon monoxide, hydrocarbons, oil and nitrogen as impurities,
Adsorbing a part of hydrocarbons and oil in the argon gas to activated carbon,
Next, it is determined whether the amount of oxygen in the argon gas exceeds a set amount necessary to react with all of hydrogen, carbon monoxide, and hydrocarbons in the argon gas,
When the amount of oxygen in the argon gas is less than or equal to the set amount, oxygen is added to exceed the set amount,
Next, carbon monoxide, hydrogen, and hydrocarbon and oxygen in the argon gas are reacted using a catalyst to generate carbon dioxide and water in a state where oxygen remains,
Next, carbon monoxide is added so that the amount of carbon monoxide in the argon gas exceeds the set amount necessary to react with all of the remaining oxygen,
Next, by reacting oxygen and carbon monoxide in the argon gas using a ruthenium catalyst, a palladium catalyst, or a mixed catalyst thereof, carbon dioxide is generated in a state where carbon monoxide remains,
Next, a method for purifying argon gas, wherein at least carbon monoxide, carbon dioxide, water, and nitrogen in the argon gas are adsorbed on an adsorbent by a pressure swing adsorption method.   The method for purifying argon gas according to claim 1, wherein palladium is used as the catalyst for reacting carbon monoxide, hydrogen, and hydrocarbon with oxygen in the argon gas.   The method for purifying argon gas according to claim 1 or 2, wherein X-type zeolite is used as the adsorbent used for the pressure swing adsorption method.   The method for purifying argon gas according to claim 1 or 2, wherein activated alumina and X-type zeolite are used as the adsorbent used for the pressure swing adsorption method.   5. The method for purifying argon gas according to claim 4, wherein the activated alumina and the X-type zeolite are arranged in layers, and a weight ratio of the activated alumina to the X-type zeolite is set to 5/95 to 30/70. .   The argon 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 adsorbed to the adsorbent by a thermal swing adsorption method at -10 ° C to -50 ° C. Gas purification method. An apparatus for purifying argon gas containing at least oxygen, hydrogen, carbon monoxide, hydrocarbons, oil and nitrogen as impurities,
An activated carbon adsorption tower into which the argon gas is introduced;
A first reactor into which argon gas flowing out from the activated carbon adsorption tower is introduced;
An oxygen supplier capable of adding oxygen to the argon gas introduced into the first reactor;
A second reactor into which argon gas flowing out of the first reactor is introduced;
A carbon monoxide supplier capable of adding carbon monoxide to the argon gas introduced into the second reactor;
An adsorption device into which argon gas flowing out from the second reactor is introduced,
In the activated carbon adsorption tower, activated carbon that adsorbs a part of hydrocarbons and oil in the argon gas is accommodated,
The first reactor contains carbon monoxide, hydrogen, and a catalyst for reacting hydrocarbons with oxygen in the argon gas,
The second reactor contains a ruthenium catalyst, a palladium catalyst, or a mixed catalyst thereof for reacting oxygen and carbon monoxide in the argon gas,
The said adsorption | suction apparatus has a PSA unit which adsorb | sucks at least carbon monoxide, carbon dioxide, water, and nitrogen in the said argon gas by a pressure swing adsorption method, The refinement | purification apparatus of the argon gas characterized by the above-mentioned.   The said adsorption | suction apparatus is a refiner | purifier of the argon gas of Claim 7 which has a TSA unit which adsorb | sucks the nitrogen in the said argon gas which flows out out of the said PSA unit by the thermal swing adsorption method at -10 degreeC--50 degreeC.

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