TWI478761B - Purifying method and purifying apparatus for argon gas - Google Patents

Description

Argon purification method and purification device

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

For example, in a device such as a ruthenium single crystal pulling furnace, a ceramic sintering furnace, a vacuum degassing apparatus for steelmaking, a tantalum plasma dissolution apparatus for a solar cell, and a polycrystalline tantalum casting furnace, argon gas is used as an ambient gas in a furnace. The argon gas recovered from such equipment for reuse is reduced in purity 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 mixed impurities are adsorbed to the adsorbent. Further, in order to efficiently adsorb the impurities, it is proposed to react the oxygen in the impurities with the combustible component and treat it as a pretreatment treatment (see Patent Documents 1 and 2).

In the method disclosed in Patent Document 1, the amount of oxygen in the argon gas is adjusted to be slightly smaller than the stoichiometric amount necessary for completely combusting combustible components such as hydrogen and carbon monoxide, and secondly, the reaction of hydrogen with oxygen is prioritized over Palladium or gold reacting with carbon monoxide and oxygen acts as a catalyst to react oxygen in argon with carbon monoxide, hydrogen, etc., thereby generating carbon dioxide and water in a state of residual carbon monoxide, and then carbon dioxide contained in argon gas and The water is adsorbed to the adsorbent at a normal temperature, and thereafter, one of the carbon oxides and nitrogen contained in the argon gas is adsorbed to the adsorbent at a temperature of -10 ° C to -50 ° C.

In the method disclosed in Patent Document 2, the amount of oxygen in the argon gas is set to an amount sufficient to completely burn the combustible components such as hydrogen and carbon monoxide, and secondly, the oxygen in the argon gas and carbon monoxide are used using a palladium-based catalyst. Hydrogen or the like is reacted to generate carbon dioxide and water in a state of residual oxygen, and then carbon dioxide and water contained in the argon gas are adsorbed to the adsorbent at normal temperature, and thereafter, oxygen and nitrogen contained in the argon gas 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 Document 1, the amount of oxygen in the argon gas is less than the stoichiometric amount necessary for completely burning hydrogen, carbon monoxide or the like in the pretreatment stage, and the reaction of hydrogen and oxygen is prioritized over A catalyst for reacting carbon monoxide with oxygen to generate carbon dioxide and water in a state of residual carbon monoxide. However, there is a drawback in that hydrogen is generated by a water gas shift reaction of carbon monoxide and water vapor which are not reacted, and thus it is impossible to cope with a situation in which hydrogen is required to be lowered. Further, in the method described in Patent Document 1, in the stage of the adsorption treatment in which the oxygen in the impurities is reacted with the combustible component, carbon dioxide and water are adsorbed to the adsorbent at normal temperature, and then carbon monoxide and nitrogen are allowed to be present. Adsorbed to the adsorbent at -10 ° C ~ -50 ° C. In the case where the adsorbent for adsorbing carbon monoxide and nitrogen is regenerated at such a low temperature, carbon monoxide is industrially disadvantageous in that it requires energy from the adsorbent as compared with nitrogen.

In the method described in Patent Document 2, the amount of oxygen in the argon gas is set to an amount sufficient to completely burn hydrogen, carbon monoxide or the like in the pretreatment stage, whereby carbon dioxide and water are generated in a state of residual oxygen. However, in order to adsorb oxygen, it is necessary to lower the temperature at the time of adsorption to about -170 °C. That is, there is a problem in that the cooling energy in the adsorption treatment is increased in order to prevent residual oxygen in the treatment before the adsorption treatment, and the purification burden is increased.

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

The method of the present invention is characterized in that it purifies an argon gas containing at least oxygen, hydrogen, carbon monoxide, and nitrogen as impurities, and the oxygen molar concentration in the argon gas is a carbon monoxide molar concentration and a hydrogen molar concentration. When the sum is 1/2 or less, the value is set to more than 1/2 by the addition of oxygen, and then the oxygen in the argon gas is reacted with carbon monoxide and hydrogen by using a catalyst, whereby residual oxygen is used. The state generates carbon dioxide and water, and secondly, the water content in the argon gas is lowered by a dehydration operation, and then at least oxygen and carbon dioxide in the impurities in the argon gas are adsorbed by a pressure swing adsorption method using a carbon-based adsorbent. Thereafter, at least nitrogen in the impurities in the argon gas is adsorbed by a temperature swing adsorption method at -10 ° C to -50 ° C.

According to the present invention, oxygen in argon gas is reacted with carbon monoxide and hydrogen to generate carbon dioxide and water in a state of residual oxygen, and secondly, a water content of argon gas is lowered by a dehydration operation. Therefore, since the main impurities of the argon gas are oxygen, carbon dioxide, and nitrogen, it is not necessary to adsorb moisture when the impurities are adsorbed by the pressure swing adsorption method, and the adsorption load is reduced, and the adsorbent for the pressure swing adsorption method can be used. A carbon-based adsorbent having a high adsorption effect of oxygen is used. Therefore, since the oxygen adsorption effect of the pressure swing adsorption method using the PSA (pressure swing adsorption) unit is improved, it is not necessary to perform oxygen conversion by a temperature swing adsorption method using a TSA (Temperature Swing adsorption) unit. The adsorption is such that the adsorption temperature of the impurities of the temperature swing adsorption method can be increased as compared with the case of adsorbing oxygen. Thereby, even if oxygen remains in the process before the adsorption treatment, the recovery rate and purity of argon gas can be improved without increasing the cooling energy.

In the present invention, in view of improving the oxygen adsorption effect of the pressure swing adsorption method, the carbon-based adsorbent is preferably a carbon molecular sieve.

The apparatus of the present invention is characterized in that it purifies an argon gas containing at least oxygen, hydrogen, carbon monoxide, and nitrogen as impurities, and includes a reactor into which the argon gas is introduced, and a concentration adjusting device which is introduced When the oxygen molar concentration in the argon gas in the reactor is 1/2 or less of the sum of the carbon monoxide molar concentration and the hydrogen molar concentration, the value is set to more than 1/2 by adding oxygen; a dryer for reducing a moisture content of the argon gas flowing out of the reactor by performing a dehydration operation; and an adsorption device connected to the dryer; the reactor is filled with a catalyst so that the reaction is The oxygen in the argon gas reacts with carbon monoxide and hydrogen to generate carbon dioxide and water in a state of residual oxygen, and the adsorption device comprises: a PSA unit which is adsorbed by a pressure swing adsorption method using a carbon-based adsorbent. At least oxygen and carbon dioxide in the impurities in the argon gas; and a TSA unit adsorbing at least nitrogen in the impurities in the argon gas by a temperature swing adsorption method at -10 ° C to -50 ° C.

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

According to the present invention, it is possible to provide a method and apparatus for purifying argon gas with high purity by effectively reducing the impurity content of argon gas, thereby reducing the burden of the subsequent adsorption treatment, reducing the energy required for purification, and reducing the energy required for purification. .

The argon purifying apparatus α shown in Fig. 1 is purified by recovering and recycling the used argon gas supplied from an argon gas supply source 1 such as a polycrystalline germanium casting furnace, and includes a heater 2. The reactor 3, the concentration adjusting device 4, the dryer 5, the cooler 8, and the adsorption device 9.

The argon gas supplied from the supply source α is dedusted by a filter or the like outside the drawing, and is introduced into the heater 2 via a gas transport mechanism (not shown) such as a blower. The trace amount of impurities contained in the argon gas to be purified is at least oxygen, hydrogen, carbon monoxide, and nitrogen, but may also contain other impurities such as carbon dioxide, hydrocarbons, and water. The concentration of the impurities in the purified argon gas is not particularly limited, and may be, for example, about 5 mol ppm to 40000 mol ppm. The heating temperature of the argon gas of the heater 2 is preferably 250 ° C or higher in order to complete the reaction in the reactor 3, and is preferably 450 ° C or less from the viewpoint of shortening the life of the catalyst.

Argon gas heated by the heater 2 is introduced into the reactor 3. When the concentration of oxygen in the argon gas introduced into the reactor 3 is 1/2 or less of the sum of the concentration of the carbon monoxide and the hydrogen molar concentration, the concentration adjusting device 4 is set to exceed the oxygen concentration by adding oxygen. 1/2 value. The concentration adjusting device 4 of the present embodiment includes a concentration measuring device 4a, an oxygen supply source 4b, an oxygen amount adjuster 4c, and a controller 4d. The concentration measuring device 4a measures the oxygen molar concentration, the carbon monoxide molar concentration, and the hydrogen molar concentration in the argon gas introduced into the reactor 3, and transmits the measurement signal to the controller 4d. When the measured oxygen molar concentration is 1/2 or less of the sum of the carbon monoxide molar concentration and the hydrogen molar concentration, the controller 4d corresponds to the amount of oxygen required to become a value exceeding 1/2. The control signal is sent to the oxygen amount adjuster 4c. The oxygen amount adjuster 4c adjusts the opening degree so as to supply oxygen corresponding to the amount of the control signal from the flow path from the oxygen supply source 4b to the reactor 3. Thereby, the oxygen molar concentration in the argon gas to be purified is set to be more than 1/2 of the sum of the carbon monoxide molar concentration and the hydrogen molar concentration.

The reactor 3 is filled with a catalyst for reacting oxygen with hydrogen and carbon monoxide. Thereby, in the reactor 3, carbon dioxide and water are generated in a state of residual oxygen by reacting oxygen in argon with carbon monoxide and hydrogen. Further, the argon gas recovered from the polycrystalline tantalum casting furnace or the like contains hydrocarbon as a combustible component, but the molar concentration thereof is usually such that the total molar concentration of hydrogen and carbon monoxide is 1/100 or less. Thereby, if the oxygen molar concentration is usually set so as to slightly exceed 1/2 of the sum of the hydrogen monoxide molar concentration and the hydrogen molar concentration, carbon dioxide and water can be generated in a state of residual oxygen. The catalyst to be charged in the reactor 3 is not particularly limited as long as it reacts with carbon monoxide and hydrogen. For example, a catalyst such as platinum, platinum alloy or palladium supported on alumina or the like can be used.

The dryer 5 reduces the moisture content of the argon gas flowing out of the reactor 3 by performing a dehydration operation. As the dryer 5, a commercially available one may be used. For example, a pressurized dehydration device that pressurizes argon gas to remove moisture by an adsorbent and regenerates the adsorbent under reduced pressure may be used, and argon gas may be added. A refrigerating type dehydration device that removes condensed water by pressure cooling, a heated regenerative dehydration device that removes moisture contained in argon by a dehydrating agent, and regenerates the dehydrating agent, thereby effectively reducing moisture The heat regenerative dehydration device is preferable in terms of the content rate, and it is preferable to remove the moisture in the argon gas by about 99%.

The adsorption device 9 is connected to the dryer 5 via a cooler 8 . The argon gas system which is subjected to dehydration treatment by the dryer 5 and has a reduced moisture content is cooled by the cooler 8 and introduced into the adsorption device 9. 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 the impurities in the argon gas by a pressure swing adsorption method at a normal temperature using a carbon-based adsorbent. The TSA unit 20 adsorbs at least nitrogen among the impurities in the argon gas by a temperature swing adsorption method at -10 ° C to -50 ° C.

The PSA unit 10 can use a well-known person. For example, the PSA unit 10 shown in FIG. 2 is a 4-tower type, and has a compressor 12 that compresses argon gas flowing out of the reactor 3, and four first to fourth adsorption towers 13, and in each adsorption tower 13 It is filled with a carbon-based adsorbent. As the carbon-based adsorbent, a carbon molecular sieve is preferred in terms of improving the oxygen adsorption effect.

The compressor 12 is connected to the inlet 13a of each adsorption tower 13 via a switching valve 13b. The inlet 13a of the adsorption tower 13 is connected to the atmosphere via a switching valve 13e and a muffler 13f, respectively.

The outlet 13k of the adsorption tower 13 is connected to the outflow pipe 13m via the switching valve 131, is connected to the pressure rising pipe 13o via the switching valve 13n, and is connected to the pressure equalizing and cleaning side pipe 13q via the switching valve 13p, and is controlled by the flow rate. The valve 13r is connected to the pressure equalizing ‧ cleaning inlet side pipe 13s.

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

The pressure increasing pipe 13o is connected to the outflow pipe 13m via the flow rate control valve 13u and the flow rate indicating regulator 13v, and the flow rate in the pressure increasing pipe 13o is adjusted to be fixed, whereby the flow rate of the argon gas introduced into the TSA unit 20 can be prevented from fluctuating.

The pressure equalization ‧ the cleaning outlet pipe 13q and the pressure equalizing ‧ the cleaning inlet pipe 13 s are connected to each other via a pair of connecting pipes 13 w , and the switching pipes 13 x are provided in the respective connecting pipes 13 w .

In the first to fourth adsorption columns 13 of the PSA unit 10, an adsorption step, a pressure reduction I step (clean gas discharge step), a pressure reduction II step (pressure equalization gas discharge step), a desorption step, and a cleaning step are sequentially performed. (Clean gas inflow step), boost I step (pressure equalization gas inflow step), and boost II step.

In other words, in the first adsorption tower 13, only the switching valve 13b and the switching valve 131 are opened, and the argon gas supplied from the reactor 3 is introduced from the compressor 12 to the first adsorption tower 13 via the switching valve 13b. In the first adsorption tower 13, the adsorption step is performed by adsorbing at least carbon dioxide and water in the introduced argon gas to the adsorbent, and the argon gas having a reduced impurity content is discharged from the first adsorption tower 13 via the outflow piping. 13m is delivered to the TSA unit 20. At this time, one of the argon gas sent to the outflow pipe 13m is sent to the other adsorption tower (the second adsorption tower 13 in the present embodiment) via the pressure increasing pipe 13o and the flow rate control valve 13u, and the second adsorption tower 13 is provided in the second adsorption tower 13 The boost II step is performed.

Then, the switching valves 13b and 131 of the first adsorption tower 13 are closed, the switching valve 13p is opened, the flow control valve 13r of the other adsorption tower (the fourth adsorption tower 13 in the present embodiment) is opened, and the switching valve 13x is opened. One. In this way, the argon gas having a relatively small impurity content in the upper portion of the first adsorption column 13 is sent to the fourth adsorption column 13 via the pressure equalization ‧ cleaning inlet pipe 13 s, and the pressure reduction step 1 is performed in the first adsorption column 13 . At this time, in the fourth adsorption tower 13, the switching valve 13e is opened to perform a cleaning step.

Then, the switching valve 13p of the first adsorption tower 13 and the flow rate control valve 13r of the fourth adsorption tower 13 are opened, and in this state, the switching valve 13e of the fourth adsorption tower 13 is closed, thereby performing the fourth adsorption tower 13 The pressure reduction II step of recovering the gas is performed until the internal pressure becomes uniform or substantially uniform between the first adsorption tower 13 and the fourth adsorption tower 13. At this time, the switching valve 13x can also be opened two depending on the situation.

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

Thereafter, the flow rate control valve 13r of the first adsorption tower 13 is opened, and the switching valves 13b and 131 of the second adsorption tower 13 in the state in which the adsorption step has been completed are closed, and the switching valve 13p is opened. In this way, the argon gas having a relatively small impurity content in the upper portion of the second adsorption tower 13 is sent to the first adsorption tower 13 via the pressure equalization ‧ cleaning inlet side pipe 13 s, and the cleaning step is performed in the first adsorption tower 13 . In the first adsorption tower 13, the gas used in the cleaning step is discharged to the atmosphere via the switching valve 13e and the muffler 13f. At this time, in the second adsorption tower 13, a pressure reduction I step is performed. Then, the switching valve 13p of the second adsorption tower 13 and the flow rate control valve 13r of the first adsorption tower 13 are opened, and in this state, the switching valve 13e of the first adsorption tower is closed, thereby performing the step I of the pressure increase. At this time, the switching valve 13x can also be opened two depending on the situation.

Thereafter, the flow rate control valve 13r of the first adsorption tower 13 is closed, and the standby state is temporarily completed. This standby state continues until the step of boosting II of the fourth adsorption tower 13 is completed. When the pressure increase of the fourth adsorption tower 13 is completed, the adsorption step is switched from the third adsorption tower 13 to the fourth adsorption tower 13, and the switching valve 13n of the first adsorption tower is opened, and the adsorption tower is in the adsorption step. In the embodiment, part of the argon gas which is sent to the outflow pipe 13m by the fourth adsorption tower 13) is sent to the first adsorption tower 13 via the pressure increasing pipe 13o and the flow rate control valve 13u, and the pressure is increased in the first adsorption tower 13 step.

Each of the above-described steps is sequentially repeated in the first to fourth adsorption columns 13, whereby the argon gas having a reduced impurity content is continuously transported to the TSA unit 20.

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

The TSA unit 20 can use a well-known person. For example, the TSA unit 20 shown in FIG. 3 is a 2-tower type, and has a heat exchange type pre-cooler 21 that pre-cools argon gas sent from the PSA unit 10, and argon gas cooled by the pre-cooler 21. The heat exchange cooler 22, the first and second adsorption towers 23, and the heat exchanger 24 covering the adsorption towers 23 are further cooled. The heat exchanger 24 cools the adsorbent by a refrigerant during the adsorption step, and heats the adsorbent by a heat medium during the desorption step. Each adsorption tower 23 has a plurality of inner tubes filled with an adsorbent. As the adsorbent, those suitable for adsorbing nitrogen can be used, and it is preferred to use an X-type zeolite or a Y-type zeolite in which the exchange ion is a divalent cation, and for example, ion exchange by calcium (Ca) or lithium (Li) can be used. Further, the divalent cation is more preferably at least one selected from the group consisting of 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 on-off valve 23b.

The inlet 23a of the adsorption tower 23 is opened to the atmosphere via the on-off valve 23c.

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

The outflow pipe 23g constitutes a part of the precooler 21, and the argon gas sent from the PSA unit 10 is cooled by the purified argon gas flowing out from the outflow pipe 23g. The purified argon gas from the outflow pipe 23g flows out through the primary side pressure control valve 231.

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

The heat exchanger 24 is a multi-tube type, and is surrounded by an outer tube 24a, a refrigerant supply source 24b, a refrigerant radiator 24c, a heat medium supply source 24d, and a heat medium radiator 24e that surround the plurality of inner tubes constituting the adsorption tower 23. Composition. Further, a plurality of on-off valves 24f for switching the refrigerant supplied from the refrigerant supply source 24b through the outer tube 24a and the refrigerant radiator 24c and supplying the self-heating medium are provided. The heat medium supplied from the source 24d is circulated through the outer tube 24a and the heat medium radiator 24e. Further, a part of the cooler 22 is formed 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 storage tank 24g.

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

In other words, in the TSA unit 20, the argon gas supplied from the PSA unit 10 is cooled in the precooler 21 and the cooler 22, and then introduced into the first adsorption tower 23 via the on-off valve 23b. At this time, the first adsorption tower 23 is cooled to -10 ° C to -50 ° C by the circulation of the refrigerant in the heat exchanger 24, and the on-off valves 23c, 23h, and 23j are closed, and the on-off valve 23f is opened, in the argon gas. At least the nitrogen contained is adsorbed to the adsorbent. Thereby, the adsorption step is performed in the first adsorption tower 23, and the purified argon gas having a reduced impurity content is discharged from the adsorption tower 23 through the primary pressure control valve 231.

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

In other words, in the second adsorption tower 23, in order to perform the desorption step after the end of the adsorption step, the on-off valves 23b and 23f are closed, and the on-off valve 23c is opened. Thereby, in the second adsorption tower 23, helium gas containing impurities is discharged to the atmosphere, and the pressure is substantially reduced to atmospheric pressure. In the desorption step, the switching valve 24f of the heat exchange unit 24 that circulates the refrigerant in the second adsorption tower 23 is switched to the closed state to stop the circulation of the refrigerant, and the refrigerant is supplied to the heat exchange unit. The on-off valve 24f that has been withdrawn and returned to the refrigerant supply source 24b is switched to the open state.

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

Then, in order to perform the cooling step in the second adsorption tower 23, the on-off valve 23j of the second adsorption tower 23 and the on-off valve 23n of the cleaning piping 23k are turned off, the on-off valve 23h of the second adsorption tower 23, and the cooling ‧ The on-off valve 23n of the pressure increasing pipe 23i is opened, and one part of the purified argon gas flowing out from the first adsorption tower 23 is introduced into the second adsorption tower 23 via the cooling/boosting pipe 23i. Thereby, the purified argon gas which has been cooled in the second adsorption tower 23 is discharged to the atmosphere via the on-off valve 23c. In the cooling step, the on-off valve 24f for circulating the heat medium is switched to the closed state to stop the circulation of the heat medium, and the heat medium is taken out from the heat exchange portion 24 to return to the on-off valve of the heat medium supply source 24d. 24f is switched to the on state. After the completion of the extraction of the heat medium, the on-off valve 24f of the heat exchange unit 24 for circulating the refrigerant in the second adsorption tower 23 is switched to the open state to be in a refrigerant circulation state. The refrigerant circulation state continues until the next step of boosting and the subsequent adsorption step ends.

Thereafter, in order to carry out the pressure increasing step in the second adsorption tower 23, the on-off valve 23c of the second adsorption tower 23 is closed, and one part of the purified argon gas flowing out from the first adsorption tower 23 is introduced, thereby making the second adsorption tower 23 Internal boost. This step of boosting continues until the internal pressure of the second adsorption tower 23 becomes substantially equal to the internal pressure of the first adsorption tower 23. When the step of raising the pressure is completed, the on-off valve 23h of the second adsorption tower 23 and the on-off valve 23n of the cooling/boosting piping 23i are closed, whereby all of the on-off valves 23b, 23c, and 23f of the second adsorption tower 23 are 23h and 23j are in a closed state, and the second adsorption tower 23 is in a standby state until the next adsorption step.

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

Further, the TSA unit 20 is not limited to the one shown in FIG. 3. For example, the number of towers may be two or more, for example, three or four.

According to the above purification apparatus α, when the argon gas containing at least oxygen, hydrogen, carbon monoxide and nitrogen is purified, the oxygen molar concentration in the argon gas is 1/2 of the sum of the carbon monoxide molar concentration and the hydrogen molar concentration. In the following case, by adding oxygen to a value exceeding 1/2 of the sum of the molar concentration of carbon monoxide and the concentration of hydrogen mole, the catalyst is used to react oxygen in the argon with carbon monoxide and hydrogen. This generates carbon dioxide and water in the state of residual oxygen, and then reduces the moisture content in the argon by a dehydration operation. Therefore, since the main impurities of the argon gas are oxygen, carbon dioxide, and nitrogen, the adsorption of the impurities by the pressure swing adsorption method is not required to adsorb the water, and the adsorption load is reduced, and the adsorbent for the pressure swing adsorption method can be used. A carbon-based adsorbent having a high adsorption effect of oxygen is used. Thereby, since the oxygen adsorption effect of the pressure swing adsorption method is improved, it is not necessary to adsorb oxygen by the temperature swing adsorption method, and the adsorption temperature of the impurities of the temperature change adsorption method can be improved as compared with the case of adsorbing oxygen. Thereby, even if oxygen remains in the process before the adsorption treatment, the recovery rate and purity of argon gas can be improved without increasing the cooling energy.

Example 1

The argon gas was purified using the above purification apparatus α. The argon gas contains 500 ppm of oxygen, 20 ppm of hydrogen, 1800 ppm of carbon monoxide, 1000 ppm of nitrogen, 20 ppm of carbon dioxide, and 20 ppm of moisture as impurities. The argon gas was introduced into the reactor 3 in a standard state at a flow rate of 3.74 L/min, and further, oxygen was added to the argon gas in a standard state at a flow rate of 3.4 mL/min. The reactor 3 was filled with 45 mL of alumina-supported platinum catalyst, and the reaction conditions were set to a temperature of 300 ° C, atmospheric pressure, and a space velocity of 5000 / h.

The argon gas flowing out of the reactor 3 was cooled to -35 ° C using a refrigerating dehydration apparatus as a dryer 5 to remove water, thereby performing a dehydration operation to reduce the moisture content of argon gas.

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

The argon gas purified by the PSA unit 10 is introduced to the TSA unit 20. The TSA unit 20 was set to a two-tower type, and each column was filled with 1.5 L of CaX-type zeolite as an adsorbent, and the adsorption pressure was set to 0.8 Mpa, the adsorption temperature was set to -35 ° C, and the desorption pressure was set to 0.1 Mpa, desorption. The temperature was set to 40 °C.

The composition of the purified argon flowing from the TSA unit 20 is shown in Table 1 below. Further, the oxygen concentration in the purified argon gas was measured by a trace oxygen concentration meter type 311 manufactured by Teledyne Co., Ltd., and the concentrations of carbon monoxide and carbon dioxide were measured by a Methanizer using a GC-FID manufactured by Shimadzu Corporation. . For the hydrogen concentration, the GC-PID measurement by GLscience was used.

Example 2

Argon gas was purified in the same manner as in Example 1 except that the oxygen addition flow rate was set to 5.00 mL/min in a standard state. The composition of the purified argon 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 changed to MgX type zeolite. The composition of the purified argon 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 set to -50 °C. The composition of the purified argon is shown in Table 1 below.

Comparative example 1

Argon gas was purified in the same manner as in Example 1 except that the oxygen addition flow rate was set to 1 mL/min in a standard state. The composition of the purified argon 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 a CaA type zeolite. The composition of the purified argon 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 was not carried out using a dryer. The composition of the purified argon is shown in Table 1 below.

According to the above Table 1, it is clear that the argon gas of each of the examples is higher in purity than the comparative examples, and the oxygen concentration is lower than that of Comparative Examples 2 and 3, and the carbon oxide concentration is lower than that of Comparative Example 1, and compared. The hydrogen concentrations of Examples 1 and 3 were lower.

1. . . Argon supply

2. . . Heater

3. . . reactor

4. . . Concentration adjusting device

4a. . . Concentration tester

4b. . . Oxygen supply

4c. . . Oxygen regulator

4d. . . Controller

5. . . Dryer

8, 22. . . Cooler

9. . . Adsorption device

10. . . PSA unit

12. . . compressor

13,23. . . Adsorption tower

13a. . . Entrance of adsorption tower 13

13b, 13e, 131,. . . Switching valve

13n, 13p, 13x

13f. . . silencer

13k. . . The outlet of the adsorption tower 13

13m, 23g. . . Outflow piping

13o. . . Boost piping

13q. . . Pressure equalization and cleaning side piping

13r, 13u. . . Flow control valve

13s. . . Pressure equalization and cleaning inlet piping

13t. . . A pressure regulating valve

13v. . . Flow indicator regulator

13w. . . Connecting piping

20. . . TSA unit

twenty one. . . Precooler

23a. . . Entrance to adsorption tower 23

23b, 23c, 23f,. . . Switch valve

23h, 23j, 23n,

24f

23e. . . The outlet of the adsorption tower 23

23i. . . Cooling ‧ boosting piping

23k. . . Cleaning pipe

23l. . . Primary side pressure control valve

23m. . . Flow meter

23o. . . Flow control valve

twenty four. . . Heat exchanger

24a. . . Outer tube

24b. . . Refrigerant supply

24c. . . Refrigerant radiator

24d. . . Heat medium supply

24e. . . Heat medium radiator

24g. . . Storage tank

α. . . Purification device

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

Fig. 2 is a block diagram showing the configuration of a pressure swing type adsorption apparatus in an apparatus for purifying an argon gas according to an embodiment of the present invention.

Fig. 3 is a block diagram showing the configuration of a variable temperature adsorption device in an apparatus for purifying argon gas according to an embodiment of the present invention.

1. . . Argon supply

2. . . Heater

3. . . reactor

4. . . Concentration adjusting device

4a. . . Concentration tester

4b. . . Oxygen supply

4c. . . Oxygen regulator

4d. . . Controller

5. . . Dryer

8. . . Cooler

9. . . Adsorption device

10. . . PSA unit

20. . . TSA unit

α. . . Purification device

Claims (3)

A method for purifying argon gas, which is characterized in that argon gas containing at least oxygen, hydrogen, carbon monoxide and nitrogen as impurities is purified, and the oxygen molar concentration in the argon gas is a carbon monoxide molar concentration and a hydrogen molar concentration. When the ratio is 1/2 or less, the value is set to more than 1/2 by adding oxygen; secondly, the oxygen in the argon gas is reacted with carbon monoxide and hydrogen by using a catalyst, thereby maintaining the state of residual oxygen. Producing carbon dioxide and water; then, reducing the moisture content in the argon gas by a dehydration operation; and then adsorbing at least the oxygen in the argon gas by a pressure swing adsorption method at a normal temperature using a carbon-based adsorbent And carbon dioxide; thereafter, at least nitrogen in the impurities in the argon gas is adsorbed by a temperature swing adsorption method at -10 ° C to -50 ° C. The method for purifying argon according to claim 1, wherein the carbon-based adsorbent is a carbon molecular sieve. An apparatus for purifying argon gas, which is characterized in that an argon gas containing at least oxygen, hydrogen, carbon monoxide and nitrogen as impurities is purified, and comprises: a reactor introduced into the argon gas; and a concentration adjusting device When the oxygen molar concentration in the argon gas introduced into the reactor is 1/2 or less of the sum of the carbon monoxide molar concentration and the hydrogen molar concentration, the value is set to more than 1/2 by adding oxygen. a dryer that reduces the moisture content of the argon gas flowing out of the reactor by performing a dehydration operation; An adsorption device connected to the dryer; the reactor is filled with a catalyst to generate carbon dioxide in a state of residual oxygen by reacting oxygen in the argon gas with carbon monoxide and hydrogen in the reactor Water; the adsorption device comprises: a PSA unit that adsorbs at least oxygen and carbon dioxide in the impurities in the argon gas by a pressure swing adsorption method at a normal temperature using a carbon-based adsorbent; and a TSA unit, which is 10 The variable temperature adsorption method at ° C to -50 ° C adsorbs at least nitrogen in the impurities in the above argon gas.