KR20110097648A - Purifying method and purifying apparatus for argon gas - Google Patents

Abstract

SUMMARY OF THE INVENTION An object of the present invention is to provide a practical method and apparatus for effectively reducing argon gas impurity content, thereby reducing the load of subsequent adsorption treatment, reducing the energy required for purification, and purifying argon gas with high purity. do.
When purifying argon gas containing at least oxygen, hydrogen, carbon monoxide and nitrogen as impurities, the oxygen molar concentration in the argon gas is set to a value exceeding 1/2 of the sum of the molar carbon monoxide concentration and the hydrogen molar concentration. Oxygen is reacted with carbon monoxide and hydrogen to produce carbon dioxide and water in the state of remaining oxygen, and then the water content is reduced by dehydration operation. Next, at least oxygen and carbon dioxide among the impurities are adsorbed by a pressure swing adsorption method using a carbon-based adsorbent, and then at least nitrogen among the impurities is adsorbed by a thermal swing adsorption method at -10 ° C to -50 ° C. Let's do it.

Description

Purification method and purification apparatus of argon gas {PURIFYING METHOD AND PURIFYING APPARATUS FOR ARGON GAS}

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

For example, in facilities such as a silicon single crystal pulling furnace, a ceramic sintering furnace, a steelmaking vacuum degassing plant, a solar cell silicon plasma melting apparatus, and a polycrystalline silicon casting furnace, argon gas is an atmosphere gas in a furnace. It is used as. The purity of argon gas recovered for reuse from such a facility is reduced by mixing hydrogen, carbon monoxide, air, or the like. Accordingly, in order to increase the purity of the recovered argon gas, adsorbing the mixed impurities to the adsorbent is performed. Moreover, in order to perform adsorption | suction of such an impurity efficiently, reacting oxygen and a flammable component in an impurity as a pretreatment of an adsorption process is proposed (refer patent document 1, patent document 2).

In the method disclosed in Patent Literature 1, the amount of oxygen in the argon gas is adjusted to be slightly less than the stoichiometric amount required to completely burn the combustible components such as hydrogen and carbon monoxide, and then the reaction of carbon monoxide and oxygen By reacting oxygen in argon gas with carbon monoxide, hydrogen and the like using palladium or gold as a catalyst which prioritizes the reaction of hydrogen and oxygen, carbon dioxide and water are produced while carbon monoxide remains, and then contained in argon gas. The resulting carbon dioxide and water are adsorbed to the adsorbent at normal temperature, and then carbon monoxide and nitrogen contained in the argon gas are adsorbed to the adsorbent at a temperature of -10 deg.

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 in the argon gas using a palladium-based catalyst. Oxygen is reacted with carbon monoxide, hydrogen, and the like to produce carbon dioxide and water in the state of remaining oxygen, and then adsorb the carbon dioxide and water contained in the argon gas to the adsorbent at room temperature, and then, contained in the argon gas. Oxygen and nitrogen are adsorbed to the adsorbent at a temperature of about -170 ° C.

Patent Document 1: Japanese Patent No. 3496079 Patent Document 2: Japanese Patent No. 3737900

In the method described in Patent Literature 1, the amount of oxygen in the argon gas in the pretreatment step is less than the stoichiometric amount required to completely burn hydrogen, carbon monoxide, and the like, and the reaction of hydrogen and oxygen is given priority over the reaction of carbon monoxide and oxygen. By using a catalyst to make carbon dioxide and water in a state where carbon monoxide remains. However, there is a drawback that the unreacted carbon monoxide causes water vapor and water gas shift reactions, so that hydrogen cannot be regenerated and reduction of hydrogen is required. In addition, in the method described in Patent Literature 1, carbon monoxide and nitrogen are adsorbed at -10 ° C to -50 ° C after adsorbing carbon dioxide and water to the adsorbent at normal temperature in the step of adsorption treatment after reacting oxygen in the impurity and the flammable component. Is adsorbed. In regenerating adsorbents that adsorb carbon monoxide and nitrogen at such low temperatures, carbon monoxide is industrially disadvantageous because it requires energy to escape from the adsorbent as compared to nitrogen.

In the method described in Patent Literature 2, carbon dioxide and water are generated in a state where oxygen is left by setting the amount of oxygen in the argon gas to a sufficient amount to completely burn hydrogen, carbon monoxide, and the like in the pretreatment step. However, in order to adsorb oxygen, it is necessary to lower the temperature at the time of adsorption to about -170 degreeC. That is, since oxygen remains in the pretreatment of the adsorption treatment, there is a problem that the cooling energy during the adsorption treatment is increased to increase the purification load.

An object of the present invention is to provide a method for purifying argon gas and a purifier that can solve the problems of the prior art as described above.

The method of the present invention is a method for purifying argon gas containing at least oxygen, hydrogen, carbon monoxide and nitrogen as impurities, wherein the molar oxygen concentration in the argon gas is 1/2 or less of the sum of the molar carbon monoxide concentration and the hydrogen molar concentration. In this case, it is set to a value exceeding 1/2 by adding oxygen, and then, by reacting oxygen in the argon gas with carbon monoxide and hydrogen using a catalyst, carbon dioxide and water in the state where oxygen remains Next, the water content in the argon gas is reduced by dehydration operation. Next, at least oxygen and carbon dioxide among the impurities in the argon gas are adsorbed by a pressure swing adsorption method using a carbon-based adsorbent. After that, at least nitrogen in the impurities in the argon gas is charged at -10 ° C to -50 ° C. It is characterized by adsorbing by the thermal swing adsorption method.

According to the present invention, carbon dioxide and water are generated in a state where oxygen is left by reacting oxygen in argon gas with carbon monoxide and hydrogen, and then the water content of argon gas is reduced by dehydration operation. Accordingly, since the main impurities of argon gas are considered to be oxygen, carbon dioxide and nitrogen, adsorption of moisture is unnecessary at the time of adsorption of impurities by the pressure swing adsorption method, thereby reducing the adsorption load and adsorbent by the pressure swing adsorption method. As the carbon-based adsorbent having a high oxygen adsorption effect is used. Since the oxygen adsorption effect by the pressure swing adsorption method using a PSA unit can be improved by this, the adsorption temperature of the oxygen by the thermal swing adsorption method using a subsequent TSA unit becomes unnecessary, and the adsorption temperature of the impurity by the thermal swing adsorption method is reduced. This can be made higher than in the case of adsorbing oxygen. Therefore, even if oxygen remains in the pretreatment of the adsorption treatment, the recovery rate and purity of argon gas can be increased without increasing the cooling energy.

In the present invention, in order to increase the oxygen adsorption effect by the pressure swing adsorption method, the carbon-based adsorbent is preferably a carbon molecular sieve.

The apparatus of the present invention is an apparatus for purifying argon gas containing at least oxygen, hydrogen, carbon monoxide and nitrogen as impurities, wherein the molar oxygen concentration in the reactor into which the argon gas is introduced and the argon gas introduced into the reactor are When is equal to or less than 1/2 of the sum of the molar concentration of carbon monoxide and the molar concentration of hydrogen, the water content rate of the argon gas flowing out of the reactor and the concentration adjusting device set to a value exceeding 1/2 by adding oxygen are dehydrated. And an adsorption device connected to the dryer, wherein oxygen in the argon gas reacts with carbon monoxide and hydrogen in the reactor so that carbon dioxide and water are generated in the state where oxygen remains. And a catalyst is charged in the reactor, and the adsorption device is in the argon gas. Thermal swing at -10 ° C to -50 ° C for at least nitrogen of the PSA unit product for adsorbing at least oxygen and carbon dioxide among the impurities in the It is characterized by including a TSA unit which adsorbs by an adsorption method.

According to the apparatus of the present invention, the method of the present invention can be carried out.

According to the present invention, by effectively reducing the impurity content of argon gas, it is possible to provide a practical method and apparatus that can reduce the load of subsequent adsorption treatment, reduce the energy required for purification, and purify argon gas with high purity. .

BRIEF DESCRIPTION OF THE DRAWINGS The figure explaining the structure of the refiner | purifier of argon gas which concerns on embodiment of this invention.
2 is an explanatory diagram of a configuration of a pressure swing adsorption device in an argon gas purification device according to an embodiment of the present invention.
3 is an explanatory diagram of a configuration of a temperature swing adsorption device in an argon gas purification device according to an embodiment of the present invention.

The argon gas purification apparatus α shown in FIG. 1 is used to purify and reuse the used argon gas supplied from an argon gas source 1 such as a polycrystalline silicon casting furnace, for example. , Reactor 3, concentration control device 4, dryer 5, cooler 8, and adsorption device 9.

Argon gas supplied from the supply source 1 is damped by the filter etc. which are not shown in figure, and is introduce | transduced into the heater 2 via gas transfer means (not shown), such as a blower. The trace impurities contained in the argon gas to be purified are considered to be at least oxygen, hydrogen, carbon monoxide and nitrogen, but may contain other impurities such as carbon dioxide, hydrocarbons and water. The concentration of the impurity in the argon gas to be purified is not particularly limited, and is, for example, about 5 mol ppm to 40000 mol ppm. The heating temperature of the argon gas by the heater 2 is preferably 250 ° C. or more in order to completely terminate the reaction in each reactor 3, 6, and is 450 ° C. or less from the viewpoint of preventing shortening of the life of the catalyst. It is preferable to set it as.

Argon gas heated by the heater (2) is introduced into the reactor (3). When the oxygen molar concentration in the argon gas introduced into the reactor 3 is 1/2 or less of the sum of the mole of carbon monoxide and the hydrogen molar concentration, the concentration adjusting apparatus 4 exceeds 1/2 by adding oxygen. Set to a value. The concentration adjusting apparatus 4 of the present embodiment includes a concentration measuring instrument 4a, an oxygen supply source 4b, an oxygen amount regulator 4c, and a controller 4d. The concentration measuring unit 4a measures the molar oxygen concentration, the carbon monoxide concentration and the hydrogen molar concentration in the argon gas introduced into the reactor 3, and sends the measurement signal to the controller 4d. When the measured oxygen molar concentration is 1/2 or less of the sum of the molar carbon monoxide concentration and the hydrogen molar concentration, the controller 4d outputs a control signal corresponding to the amount of oxygen necessary to set the value exceeding 1/2 to the oxygen amount regulator 4c. Send to). The oxygen amount regulator 4c adjusts the opening degree so that the amount of oxygen according to the control signal is supplied to the flow passage from the oxygen supply source 4b to the reactor 3. Accordingly, the molar oxygen concentration in the argon gas to be purified is set to a value exceeding 1/2 of the sum of the molar carbon monoxide concentration and the hydrogen molar concentration.

In the reactor 3, a catalyst for reacting oxygen with hydrogen and carbon monoxide is charged. As a result, the oxygen in the argon gas reacts with carbon monoxide and hydrogen in the reactor 3, whereby carbon dioxide and water are generated in the state where oxygen remains. In addition, although argon gas recovered from a polycrystalline silicon casting furnace or the like contains a hydrocarbon as a combustible component, the molar concentration thereof is usually 1/100 or less of the total molar concentration of hydrogen and carbon monoxide. Therefore, when the oxygen molar concentration is usually set to slightly exceed 1/2 of the sum of the molar carbon monoxide concentration and the molar hydrogen concentration, carbon dioxide and water can be produced in the state where oxygen remains. The catalyst charged in the reactor 3 is not particularly limited as long as oxygen is reacted with carbon monoxide and hydrogen. For example, a catalyst in which platinum, platinum alloy, palladium and the like is supported may be used.

The dryer 5 reduces the moisture content rate of the argon gas which flows out from the reactor 3 by performing dehydration operation. As the dryer 5, a commercially available one may be used. For example, a pressurized dehydration apparatus for pressurizing argon gas to remove water by the adsorbent and regenerating the adsorbent under reduced pressure, and for freezing to remove condensed water by pressurizing and cooling the argon gas. A dehydration device, a heat regeneration dehydration device for removing moisture contained in the argon gas by a dehydration agent, and heating and regenerating the dehydration agent may be used. A heat regeneration dehydration device is preferable for effectively reducing the water content. It is good to be able to remove about 99% of moisture in argon gas.

The adsorption device 9 is connected to the dryer 5 via the cooler 8. The argon gas dewatered by the dryer 5 and reduced in water content is introduced into the adsorption device 9 after being cooled by the cooler 8. The adsorption device 9 has a PSA unit 10 and a TSA unit 20. The PSA unit 10 adsorbs at least oxygen and carbon dioxide among impurities in argon gas by a pressure swing adsorption method at room temperature using a carbon-based adsorbent. The TSA unit 20 adsorbs at least nitrogen of impurities in the argon gas by a thermal swing adsorption method at -10 ° C to -50 ° C.

The PSA unit 10 can use a well-known thing. For example, the PSA unit 10 shown in FIG. 2 is a four tower type, and has a compressor 12 for compressing the argon gas flowing out of the reactor 3, and four first to fourth adsorption towers 13, and each adsorption tower. Carbon-based adsorbent is filled in (13). As the carbon-based adsorbent, a carbon molecular sieve is preferable for enhancing the oxygen adsorption effect.

The compressor 12 is connected to the inlet 13a of each adsorption tower 13 via the switching valve 13b. Each inlet 13a of the adsorption tower 13 is connected to the atmosphere through a switching valve 13e and a silencer 13f.

Each outlet 13k of the adsorption tower 13 is connected to the outflow pipe 13m through the switching valve 131, and is connected to the boosting pipe 13o through the switching valve 13n, and through the switching valve 13p. It is connected to the pressure equalizing / cleaning outflow piping 13q, and is connected to the pressure equalizing / cleaning inflow piping 13s via the flow control valve 13r.

The outflow pipe 13m is connected to the TSA unit 20 via the pressure regulating valve 13t, and the pressure of the argon gas introduced into the TSA unit 20 becomes constant.

The boosting pipe 13o is connected to the outflow pipe 13m via the flow control valve 13u and the flow rate indicating controller 13v, and the TSA unit 20 is adjusted by adjusting the flow rate in the boosting pipe 13o constantly. Flow rate fluctuations of the argon gas introduced into the are prevented.

The equalization / cleaning outflow piping 13q and the equalization / cleaning inflow piping 13s are connected to each other via a pair of connecting piping 13w, and a switching valve 13x is provided in each of the connecting piping 13w. have.

In each of the first to fourth adsorption towers 13 of the PSA unit 10, the adsorption step, the decompression step I (cleaning gas outflow step), the depressurization step II (uniform pressure gas outflow step), the desorption step, the cleaning step (cleaning gas) Inflow process), the boost I process (pressure equalizing gas inflow process), and the boost II process are performed sequentially.

That is, in the first adsorption tower 13, only the switching valve 13b and the switching valve 13l are opened, and the argon gas supplied from the reactor 3 passes from the compressor 12 through the switching valve 13b to the first absorption tower. Is introduced in (13). As a result, at least carbon dioxide and water in the argon gas introduced in the first adsorption tower 13 are adsorbed to the adsorbent, so that the adsorption step is performed, and argon gas having a reduced content of impurities is discharged from the first adsorption tower 13 (13m). ) Is sent to the TSA unit 20. At this time, a part of argon gas sent to the outflow pipe 13m is sent to another adsorption tower (second adsorption tower 13 in this embodiment) through the booster piping 13o and the flow control valve 13u, The boost II process is performed in the 2 adsorption tower 13.

Next, the switching valves 13b and 13l of the first adsorption tower 13 are closed, the switching valve 13p is opened, and the flow control valve of another adsorption tower (fourth adsorption tower 13 in this embodiment) ( 13r) is opened and one of the switching valves 13x is opened. As a result, argon gas having a relatively low impurity content in the upper portion of the first adsorption tower 13 is sent to the fourth adsorption tower 13 through the pressure equalizing / cleaning inlet pipe 13s, and the decompression I is performed in the first adsorption tower 13. The process is performed. At this time, in the 4th adsorption tower 13, the switching valve 13e is opened and a washing process is performed.

Next, the switching valve 13p of the first adsorption tower 13 and the flow control valve 13r of the fourth adsorption tower 13 are opened, thereby closing the switching valve 13e of the fourth adsorption tower 13. The pressure reduction II process of recovering gas to the fourth adsorption tower 13 is performed between the first adsorption tower 13 and the fourth adsorption tower 13 until the internal pressures are uniform or almost uniform. At this time, both of the switching valves 13x may be opened in some cases.

Next, by opening the switching valve 13e of the first adsorption tower 13 and closing the switching valve 13p, a desorption process of desorbing impurities from the adsorbent is performed, and the impurities are discharged together with the gas to silencer 13f. Through the atmosphere.

Next, the flow control valve 13r of the 1st adsorption tower 13 is opened, the switching valves 13b and 13l of the 2nd adsorption tower 13 of the state which completed the adsorption process are closed, and the switching valve 13p is closed. Open. As a result, argon gas having a relatively low impurity content in the upper portion of the second adsorption tower 13 is sent to the first adsorption tower 13 through the pressure equalizing / cleaning inlet pipe 13s, and the cleaning step is performed in the first adsorption tower 13. This is done. The gas used for the washing | cleaning process in the 1st adsorption tower 13 is discharged | emitted to air | atmosphere through the switching valve 13e and the silencer 13f. At this time, the pressure reduction I process is performed in the 2nd adsorption tower 13. Next, the step-up I process was performed by closing the switching valve 13e of the first adsorption tower with the switching valve 13p of the second adsorption tower 13 and the flow control valve 13r of the first adsorption tower 13 open. All. At this time, both of the switching valves 13x may be opened in some cases.

Then, the flow control valve 13r of the 1st adsorption tower 13 is closed, and once, it will be in the standby state without a process. This is continued until the pressure raising II process of the 4th adsorption tower 13 is completed. When the boosting 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 switching valve 13n of the first adsorption tower is opened to separate the adsorption tower in the adsorption process. In the present embodiment, a part of the argon gas sent from the fourth adsorption tower 13 to the outflow pipe 13m is sent to the first adsorption tower 13 via the booster pipe 13o and the flow control valve 13u. The boost II process is performed in the 1st adsorption tower 13.

Each of the above steps is sequentially repeated in each of the first to fourth adsorption towers 13 so that argon gas having reduced impurity content is continuously sent to the TSA unit 20.

In addition, the PSA unit 10 is not limited to that shown in FIG. 2, and the number of towers may be two or three, for example, in addition to four.

The TSA unit 20 may use a known one. For example, the TSA unit 20 shown in FIG. 3 is a two-column type, and is pre-cooled by a heat exchange type precooler 21 for pre-cooling the argon gas sent from the PSA unit 10 and a precooler 21. The heat exchange cooler 22 which further cools argon gas, and the heat exchange part 24 which covers the 1st, 2nd adsorption tower 23, and each adsorption tower 23 are provided. The heat exchanger 24 cools the adsorbent with a refrigerant during the adsorption step, and heats the adsorbent with a fruit during the desorption step. Each adsorption tower 23 has a plurality of inner tubes filled with an adsorbent. As the adsorbent, one suitable for nitrogen adsorption is used, and it is preferable to use X-type zeolite or Y-type zeolite whose exchange ion is a divalent cation. For example, a zeolite-based adsorbent ion-exchanged with calcium (Ca) or lithium (Li) is used. It is more preferable that the divalent cation is at least one selected from magnesium (Mg), calcium (Ca), strontium (Sr) and barium (Ba).

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

Each of the inlets 23a of the adsorption tower 23 is connected to the atmosphere through the on-off valve 23c.

Each outlet 23e of the adsorption tower 23 is connected to the outflow pipe 23g through the on-off valve 23f, and is connected to the cooling / boosting pipe 23i via the on / off valve 23h, and opens / closes the valve 23j. Is connected to the washing pipe 23k.

The outflow piping 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 piping 23g. The argon gas purified from the outflow pipe 23g flows out through the primary pressure control valve 231.

The cooling and boosting piping 23i and the washing piping 23k are connected to the outflow piping 23g via the flowmeter 23m, the flow control valve 23o, and the opening / closing valve 23n.

The heat exchange part 24 is a multi-pipe type, and surrounds a plurality of inner tubes constituting the adsorption tower 23, the coolant supply source 24b, the coolant radiator 24c, the fruit supply source 24d, and the fruit It consists of a radiator 24e. The refrigerant supplied from the refrigerant supply source 24b is circulated through the external appearance 24a and the refrigerant radiator 24c, and the fruit supplied from the fruit supply source 24d is supplied with the external appearance 24a and the fruit radiator 24e. A plurality of opening / closing valves 24f for switching to the state to circulate through is provided. In addition, a part of the cooler 22 is formed by a pipe branched from the coolant radiator 24c, and the argon gas is cooled in the cooler 22 by the coolant supplied from the coolant supply source 24b, and the coolant is tanked. Reflux to (24 g).

In each of the first and second adsorption towers 23 of the TSA unit 20, an adsorption step, a desorption step, a washing step, a cooling step, and a boosting step are sequentially performed.

That is, in the TSA unit 20, after argon gas supplied from the PSA unit 10 is cooled in the precooler 21 and the cooler 22, the argon gas is supplied to the first adsorption tower 23 through the opening / closing valve 23b. Is introduced. 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, and the open / close valves 23c, 23h, 23j are closed, and the open / close valve ( 23f) is opened and at least nitrogen contained in the argon gas is adsorbed to the adsorbent. Thereby, the adsorption process is performed in the 1st adsorption tower 23, and refine | purified argon gas from which the content rate of an impurity was reduced flows out from the adsorption tower 23 through the primary side pressure control valve 231.

While the adsorption step is performed in the first adsorption tower 23, the desorption step, the washing step, the cooling step, and the step-up step are performed in the second adsorption tower 23.

That is, in the 2nd adsorption tower 23, since a desorption process is performed after an adsorption process is complete | finished, switching valve 23b, 23f is closed, and opening / closing valve 23c is opened. Thereby, in the 2nd adsorption tower 23, helium gas containing an impurity is discharge | released to air | atmosphere, and pressure falls to almost atmospheric pressure. In this desorption step, the opening and closing valve 24f of the heat exchange part 24 which has circulated the refrigerant in the adsorption step in the second adsorption tower 23 is switched to a closed state to stop the circulation of the refrigerant, and the refrigerant is exchanged with the heat exchange part ( The on-off valve 24L, which is taken out of 24 and returned to the refrigerant supply source 24b, is switched to the open state.

Next, in order to perform the cleaning process in the second adsorption tower 23, the opening / closing valves 23c and 23j of the second adsorption tower 23 and the opening / closing valve 23n of the cleaning pipe 23k are opened. A part of purified argon gas heated by the heat exchange in the heat exchange type precooler 21 is introduced into the second adsorption tower 23 through the cleaning pipe 23k. Accordingly, in the second adsorption tower 23, desorption of impurities from the adsorbent and washing with purified argon gas are performed, and the argon gas used for the washing is discharged to the atmosphere together with the impurities from the on-off valve 23c. In this washing | cleaning process, the switching valve 24f of the heat exchange part 24 for circulating a fruit in the 2nd adsorption tower 23 is switched to an open state.

Next, in order to perform a cooling process in the second adsorption tower 23, the opening / closing valve 23j of the second adsorption tower 23 and the opening / closing valve 23n of the cleaning pipe 23k are closed, and the second The opening / closing valve 23h of the adsorption tower 23 and the opening / closing valve 23n of the cooling / boosting piping 23i are in an open state, and a part of the purified argon gas flowing out of the first adsorption tower 23 is used for cooling and boosting. It is introduced into the second adsorption tower 23 through the pipe 23i. Accordingly, the purified argon gas cooled inside the second adsorption tower 23 is discharged into the atmosphere through the on / off valve 23c. In this cooling step, the on / off valve 24f for circulating the fruit is switched to the closed state to stop the fruit circulation, and the on / off valve 24f for removing the fruit from the heat exchanger 24 and returning it to the fruit supply source 24d is provided. Switch to the open state. After the fruit extraction is finished, the opening / closing valve 24f of the heat exchanger 24 for circulating the refrigerant in the second adsorption tower 23 is switched to an open state to bring the refrigerant into a circulation state. This refrigerant circulation state is continued until the next boosting step and the adsorption step following this are completed.

Next, in order to perform the step-up process in the second adsorption tower 23, the opening / closing valve 23c of the second adsorption tower 23 is closed and a part of the purified argon gas flowing out of the first adsorption tower 23 is introduced. The inside of the second adsorption tower 23 is boosted. This boosting process is continued until the internal pressure of the 2nd adsorption tower 23 becomes substantially the same as the internal pressure of the 1st adsorption tower 23. When the boosting step is completed, the opening / closing valve 23h of the second adsorption tower 23 and the opening / closing valve 23n of the cooling / boosting piping 23i are closed, thereby all the opening / closing valves of the second adsorption tower 23 are closed. (23b, 23c, 23f, 23h, 23j) are in a closed state, and the second adsorption tower 23 is in a standby state until the next adsorption step.

The adsorption process of the 2nd adsorption tower 23 is performed similarly to the adsorption process of the 1st adsorption tower 23. While the adsorption process is being performed in the second adsorption tower 23, the desorption process, the cleaning process, the cooling process, and the boosting process proceed in the first adsorption tower 23 as in the second adsorption tower 23.

In addition, the TSA unit 20 is not limited to that shown in FIG. 3, for example, the number of towers may be two or more, such as three or four.

According to the said purification device (alpha), when refine | purifying the argon gas containing oxygen, hydrogen, carbon monoxide, and nitrogen at least, the oxygen molar concentration in the argon gas is 1/2 or less of the sum of molar carbon monoxide concentration and hydrogen molar concentration. In this case, after the oxygen is added to a value exceeding 1/2 of the sum of the molar concentration of carbon monoxide and the molar concentration of hydrogen, oxygen in the argon gas is reacted with carbon monoxide and hydrogen by using a catalyst to produce oxygen. Carbon dioxide and water are produced in the state which remained, and then the water content in the argon gas is reduced by dehydration operation. Accordingly, since the main impurities of argon gas are considered to be oxygen, carbon dioxide, and nitrogen, adsorption of moisture is unnecessary at the time of adsorption of impurities by the subsequent pressure swing adsorption method, so that the adsorption load is reduced, and the pressure swing adsorption method is further reduced. Is a carbon-based adsorbent with high oxygen adsorption effect. As a result, the oxygen adsorption effect by the pressure swing adsorption method can be enhanced, so that adsorption of oxygen by the subsequent thermal swing adsorption method is unnecessary, and the adsorption temperature of impurities by the thermal swing adsorption method is higher than that in the case of adsorbing oxygen. Can be made higher. Therefore, even if oxygen remains in the pretreatment of the adsorption treatment, the recovery rate and purity of argon gas can be increased without increasing the cooling energy.

Example 1

The argon gas was refine | purified using the said refiner ((alpha)). Argon gas contains 500 mol ppm of oxygen, 20 mol ppm of hydrogen, 1800 mol ppm of carbon monoxide, 1000 mol ppm of nitrogen, 20 mol ppm of carbon dioxide, and 20 mol ppm of water as impurities. This argon gas was introduced into the reactor 3 at a flow rate of 3.74 L / min in a standard state, and oxygen was further added to the argon gas at a flow rate of 3.4 mL / min in a standard state. The reactor 3 was charged with 45 ml of alumina-supported platinum catalysts, and the reaction conditions were 300 ° C., atmospheric pressure, and space velocity 5000 / h.

The argon gas which flowed out from the reactor 3 was cooled to -35 degreeC using the refrigeration dehydration apparatus as the dryer 5, and water was removed and dehydration operation was performed, and the water content rate of argon gas was reduced.

After the argon gas flowing out from the dryer 5 was cooled in the cooler 8, the adsorption device 9 reduced the content of impurities. The PSA unit 10 is a three-column type, and each column is filled with 1.25 L of carbon molecular sieve (3k-172 manufactured by Nippon Enviro Chemicals) of cylindrical coal briquettes having a diameter of 2 mm as an adsorbent, and the adsorption pressure is 0.9. MPa and the desorption pressure were 0.1 MPa.

Argon gas purified by the PSA unit 10 was introduced into the TSA unit 20. The TSA unit 20 was a two-column type, and 1.5 L of CaX zeolite was charged to each column as an adsorbent, the adsorption pressure was 0.8 MPa, the adsorption temperature was -35 ° C, the desorption pressure was 0.1 MPa, and the desorption temperature was 40 ° C. .

The composition of the purified argon gas flowing out from the TSA unit 20 is shown in Table 1 below. In addition, the oxygen concentration in the purified argon gas is specified by a trace oxygen concentration meter type 311 manufactured by Teledyne, and the concentrations of carbon monoxide and carbon dioxide are obtained through a metamerizer using GC-FID manufactured by Shimadzu Corporation. Measured. The hydrogen concentration was measured using GC-PID manufactured by GLscience.

Example 2

Argon gas was purified in the same manner as in Example 1 except that the addition flow rate of oxygen was set to 5.00 ml / min in the standard state. The composition of the purified argon gas is shown in Table 1 below.

Example 3

Argon gas was purified in the same manner as in Example 1 except that the adsorbent used in the TSA unit 20 was used as the MgX zeolite. The composition of the purified argon gas is shown in Table 1 below.

Example 4

Argon gas was purified in the same manner as in Example 1 except that the adsorption temperature in the TSA unit 20 was -50 ° C. The composition of the purified argon gas is shown in Table 1 below.

Comparative Example 1

The argon gas was purified in the same manner as in Example 1 except that the flow rate of oxygen addition was 1 ml / min in the standard state. The composition of the purified argon gas is shown in Table 1 below.

Comparative Example 2

Argon gas was purified in the same manner as in Example 1 except that the adsorbent used in the PSA unit 10 was used as a CaA zeolite. The composition of the purified argon gas is shown in Table 1 below.

Comparative Example 3

Argon gas was purified in the same manner as in Example 1 except that the dehydration operation with a drier was not performed. The composition of the purified argon gas is shown in Table 1 below.

From the above Table 1, according to each Example, argon gas purity is higher than each Comparative Example, oxygen concentration is lower than Comparative Example 2, Comparative Example 3, carbon monoxide concentration is lower than Comparative Example 1, Comparative Example 1, Comparative Example 3 It can be confirmed that the hydrogen concentration is lower than.

α: refining device, 3: reactor, 4: concentration controller, 5: dryer, 9 adsorption device, 10: PSA unit, 20: TSA unit

Claims (3)

A method of purifying argon gas containing at least oxygen, hydrogen, carbon monoxide and nitrogen as impurities,
When the molar oxygen concentration in the argon gas is 1/2 or less of the sum of the molar concentration of carbon monoxide and the molar hydrogen concentration, it is set to a value exceeding 1/2 by adding oxygen,
Next, oxygen in the argon gas is reacted with carbon monoxide and hydrogen using a catalyst to produce carbon dioxide and water in the state of remaining oxygen,
Next, the water content in the argon gas is reduced by dehydration operation,
Next, at least oxygen and carbon dioxide among the impurities in the argon gas are adsorbed by a pressure swing adsorption method using a carbon-based adsorbent,
Thereafter, at least nitrogen among the impurities in the argon gas is adsorbed by the thermal swing adsorption method at -10 ° C to -50 ° C. The method of claim 1, wherein the carbon-based adsorbent is a carbon molecular sieve. An apparatus for purifying argon gas containing at least oxygen, hydrogen, carbon monoxide and nitrogen as impurities,
A reactor into which the argon gas is introduced,
When the oxygen molar concentration in the argon gas introduced into the reactor is 1/2 or less of the sum of the molar carbon monoxide concentration and the hydrogen molar concentration, a concentration adjusting device which sets the value to more than 1/2 by adding oxygen,
A dryer for reducing the water content of the argon gas flowing out of the reactor by performing a dehydration operation;
An adsorption device connected to the dryer,
In the reactor, the oxygen in the argon gas reacts with carbon monoxide and hydrogen, so that a catalyst is charged in the reactor so that carbon dioxide and water are produced in the state where oxygen remains,
The adsorption device includes a PSA unit which adsorbs at least oxygen and carbon dioxide among the impurities in the argon gas by a pressure swing adsorption method using a carbon-based adsorbent, and at least nitrogen in the impurities in the argon gas at -10 ° C. The argon gas refiner | purifier characterized by including the TSA unit made to adsorb | suck by the thermal swing adsorption method at --50 degreeC.

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