TWI476038B - 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 which reacts 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 made smaller than the stoichiometric amount necessary for completely burning hydrogen, carbon monoxide or the like, and the reaction of hydrogen and oxygen is used in preference to the reaction of carbon monoxide with oxygen. catalyst. Therefore, complete combustion of hydrogen can be achieved by the reaction, and unreacted carbon monoxide is actively retained. However, a trace amount of hydrogen is difficult to remove by adsorption treatment, but in the use of argon gas, the residual of hydrogen is often allowed. On the other hand, carbon monoxide becomes catalytically toxic and is more difficult to adsorb by ordinary adsorbents such as zeolite than carbon dioxide. That is, in the stage before the adsorption treatment, complete combustion of hydrogen which is less than a residual problem can be achieved, and on the other hand, the following unreasonable treatment is performed, that is, the function of reducing the catalyst is lowered and the adsorption is difficult. Carbon monoxide actively remains.

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, and the oxygen in the argon gas, carbon monoxide, hydrogen, or the like is performed using a palladium-based catalyst. reaction. Therefore, complete combustion of hydrogen, carbon monoxide or the like can be achieved by the reaction, and oxygen which is often a problem in the use of argon gas remains actively. However, as described above, in the use of argon gas, the residual of hydrogen is allowed to be large. On the other hand, in order to adsorb oxygen, it is necessary to lower the temperature at the time of adsorption to about -170 °C. That is, the reaction of the stage before the adsorption treatment realizes complete combustion of hydrogen which is less than the residual problem, and on the other hand, the following unreasonable treatment, that is, the increase of the cooling energy by the adsorption treatment is caused. Oxygen which has a large purification burden remains actively.

According to the unreasonable prior art as described above, there is a problem that the management cost or the construction cost of the argon recovery apparatus increases. 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 sets the oxygen molar concentration in the argon gas to be less than the concentration of carbon monoxide and hydrogen. 1/2 of the sum of the ear concentrations, and secondly, using a catalyst that reacts carbon monoxide with oxygen in preference to the reaction of hydrogen and oxygen, the oxygen in the argon gas is reacted with carbon monoxide and hydrogen, thereby leaving a state of residual hydrogen. Carbon dioxide and water are generated, and thereafter, an adsorbent is used to reduce the content of impurities in the above argon gas.

According to the present invention, the oxygen molar concentration in the argon gas is set to be less than 1/2 of the sum of the carbon monoxide molar concentration and the hydrogen molar concentration, and a catalyst for reacting carbon monoxide with oxygen is preferred over the reaction of hydrogen with oxygen. The oxygen in argon is reacted with carbon monoxide and hydrogen. Thereby, hydrogen which is less likely to remain in the residual state is actively retained, and in the case of adsorption removal, complete combustion of oxygen which increases the cooling energy can be achieved, and further, there is no need to reduce the catalyst function. Carbon monoxide is more difficult to adsorb than carbon dioxide. Thereby, the management of the purification apparatus is facilitated, and miniaturization can be achieved, thereby reducing energy consumption.

In the method of the present invention, in order to make the reaction of carbon monoxide and oxygen preferentially react with hydrogen and oxygen, the above catalyst preferably contains platinum as a main component. In the method of the present invention, in order to efficiently carry out the adsorption of carbon dioxide, water, and nitrogen, it is preferred to use a pressure-sensitive adsorption method at normal temperature when the content of impurities in the argon gas is lowered by using an adsorbent. After adsorbing at least carbon dioxide and water in the impurities, at least nitrogen in the impurities is adsorbed by a temperature swing adsorption method at -10 ° C to -50 ° C.

In the method of the present invention, it is preferred to set the oxygen molar concentration in the argon gas to a value exceeding 1/2 of the carbon monoxide molar concentration.

Thereby, it is possible to achieve complete combustion of one of the carbon oxides with the function of reducing the catalyst. In this case, it is preferable to add hydrogen when the oxygen molar concentration in the argon gas is set to be 1/2 or more of the sum of the carbon monoxide molar concentration and the hydrogen molar concentration. Oxygen is added when the oxygen molar concentration is less than or equal to 1/2 of the carbon monoxide molar concentration. Thereby, since carbon monoxide is not added when the oxygen molar concentration is set, the reaction product of carbon monoxide and water can be prevented from lowering the purity of the argon gas.

The apparatus of the present invention is characterized in that it purifies 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 The oxygen molar concentration in the argon gas in the reactor is set to be less than 1/2 of the sum of the carbon monoxide molar concentration and the hydrogen molar concentration; and an adsorption device connected to the reactor; carbon monoxide and oxygen The catalyst having a reaction preferentially reacting with hydrogen and oxygen is filled in the reactor so that carbon dioxide and water are generated in a state of residual hydrogen by reacting oxygen in the argon gas in the reactor with carbon monoxide and hydrogen. The adsorption device includes an adsorbent for reducing the content of impurities in the argon gas flowing out of the reactor.

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 purity purification process for improving the purity of the recovered impurity-containing argon gas, thereby preventing the function of the purification catalyst from being reduced, reducing the purification burden, and contributing to reducing the management cost and construction of the recovery equipment. Method and device for the fee.

The argon purifying apparatus α shown in Fig. 1 is purified by recovering and recycling the used chlorine gas supplied from an argon gas supply source 1 such as a polycrystalline germanium casting furnace, and includes a heater 2 and a reaction. The device 3, the concentration adjusting device 4, the cooler 5, and the adsorption device 6.

The chlorine 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 the air blower 7 as a gas transport step. The impurities contained in the argon gas to be purified are at least oxygen, hydrogen, carbon monoxide, and nitrogen, but may contain other impurities such as carbon dioxide or hydrocarbons. 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. With respect to the heating temperature of the argon gas of the heater 2, it is preferable to prevent the carbon monoxide from adsorbing to the active site of the catalyst in the reactor 3 and hinder the reaction between hydrogen and oxygen, preferably at 200 ° C or higher. From the viewpoint of shortening the life of the catalyst, it is preferably set to 300 ° C or lower.

Argon gas heated by the heater 2 is introduced into the reactor 3. The concentration adjusting device 4 sets the oxygen molar concentration in the argon gas introduced into the reactor 3 via the heater 2 to be less than 1/2 of the sum of the carbon monoxide molar concentration and the hydrogen molar concentration. The concentration adjusting device 4 of the present embodiment includes a concentration measuring device 4a, a hydrogen supply source 4b, a hydrogen amount adjuster 4c, an oxygen supply source 4d, an oxygen amount adjuster 4e, and a controller 4f. 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 heater 2, and transmits the measurement signal to the controller 4f. The controller 4f is a control signal corresponding to the amount of hydrogen necessary to become less than 1/2 when the measured oxygen molar concentration is 1/2 or more of the sum of the carbon monoxide molar concentration and the hydrogen molar concentration. It is sent to the hydrogen amount adjuster 4c, and when the measured oxygen molar concentration is 1/2 or less of the carbon monoxide molar concentration, the control signal corresponding to the amount of oxygen necessary for exceeding 1/2 is transmitted to the oxygen amount. Regulator 4e. The hydrogen amount adjuster 4c adjusts the opening degree so as to supply hydrogen corresponding to the amount of the control signal from the flow path from the hydrogen supply source 4b to the reactor 3. The oxygen amount adjuster 4e 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 4d to the reactor 3. Thereby, when setting the oxygen molar concentration in the argon gas to be purified, hydrogen is added when the oxygen molar concentration is 1/2 or more of the sum of the carbon monoxide molar concentration and the hydrogen molar concentration, in the oxygen molar Oxygen is added when the concentration is less than or equal to 1/2 of the concentration of carbon monoxide.

The reactor 3 is filled with a catalyst that reacts carbon monoxide with oxygen in preference to hydrogen and oxygen. Thereby, in the reactor 3, oxygen in the argon gas is reacted with carbon monoxide and hydrogen at a temperature of 200 ° C to 300 ° C to generate carbon dioxide and water in a state of residual hydrogen. The catalyst contains platinum as a main component, and in the present embodiment, a platinum catalyst supported by alumina is used. The catalyst is not limited to platinum, and for example, a platinum alloy may be used, and a small amount of other components such as palladium may be contained.

The cooler 5 is connected to the reactor 3, and the argon gas flowing out of the reactor 3 is cooled to about 40 °C. The argon gas cooled by the cooler 5 is introduced to the adsorption device 6.

The adsorption device 6 has an adsorbent for reducing the content of impurities in the argon gas flowing out of the reactor 3. The adsorption device 6 of the present embodiment has a PSA (pressure swing adsorption) unit 10 for adsorbing impurities in argon gas by a pressure swing adsorption method at normal temperature, and by -10 ° C to -50 ° C The TSA (Temperature Swing adsorption) unit 20 for adsorbing impurities in argon under the variable temperature adsorption method is subjected to adsorption by a pressure swing adsorption method and then subjected to a temperature swing adsorption method.

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 an adsorbent. As the adsorbent, those suitable for adsorbing carbon dioxide and water can be used, and for example, activated alumina, activated carbon, and CaA-type zeolite can be used.

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

The outlet 13k of the adsorption tower 13 is connected to the outflow pipe 13m via the switching valve 13l, is connected to the pressure rising pipe 13o via the switching valve 13n, and is connected to the pressure equalizing/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 the pair of connecting pipes 13 w , and the switching pipe 13 x is provided in each of the 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 into the first adsorption tower 13 from the compressor 12 via the switching valve 13b. In this way, at least carbon dioxide and moisture in the argon gas introduced into the first adsorption column 13 are adsorbed to the adsorbent, whereby the adsorption step is performed, and the argon gas having a reduced impurity content is supplied from the first adsorption tower 13 through the outflow pipe 13m. It is delivered to the TSA unit 20. At this time, one part of the chlorine 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, so that the second adsorption tower 13 is in the second adsorption tower 13 The boost II step 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 flow rate control valve 13r of the other adsorption tower (the fourth adsorption tower 13 in the present embodiment) is opened to open the switching valve 13x. 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 is reduced 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 the switching valve 13e of the fourth adsorption tower 13 is closed in this state, thereby being implemented in the fourth adsorption tower 13. In the pressure reduction II step of recovering the gas, 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.

Next, the switching valve 13e of the first adsorption tower 13 is opened, and the switching valve 13p is closed, whereby a 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.

Next, the flow rate control valve 13r of the first adsorption tower 13 is opened, and the switching valves 13b and 13l of the second adsorption tower 13 in the state 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, the pressure reduction I step is performed in the second adsorption tower 13. Then, the switching valve 13p of the second adsorption tower 13 and the 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 column 13 is completed, the adsorption step is switched from the third adsorption column 13 to the fourth adsorption column 13, and the switching valve 13n of the first adsorption column is opened, from the other adsorption column in the adsorption step. In the present embodiment, a portion of the argon gas that has been transported to the outflow pipe 13m by the fourth adsorption column 13) is sent to the first adsorption column 13 via the pressure increasing pipe 13o and the flow rate control valve 13u, thereby being lifted in the first adsorption column 13 Pressure II step.

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

The TSA unit 20 can use a well-known person. For example, the TSA unit 20 of the present embodiment shown in FIG. 3 is a two-column type, and has a heat exchange type pre-cooler 21 for precooling argon gas sent from the PSA unit 10, and a precooler 21 for the precooler 21 The cooled argon gas is further cooled by the heat exchange cooler 22, the first and second adsorption towers 23, and the heat exchanger 24 covering the adsorption towers 23. When the heat exchanger 24 is in the adsorption step, the adsorbent is cooled by the refrigerant, and in the desorption step, the adsorbent is heated by the heat medium. 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 for example, a CaX-type zeolite can be used.

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 and pressure increasing 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 and boosting piping 23i and the cleaning piping 23k are connected to the outflow piping 23g via the flow meter 23m, the flow rate control valve 23o, and the switching valve 23n.

The heat exchanger 24 is a multi-tube type, and has 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. 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 circulated in the heat exchanger 24 by the refrigerant, and is cooled to -10 ° C to -50 ° C. The on-off valves 23c, 23h, and 23j are closed, and the on-off valve 23f is opened. At least nitrogen is adsorbed to the adsorbent. By this, the adsorption step is performed in the first adsorption tower 23, and the purified chlorine gas having a reduced impurity content is discharged from the adsorption tower 23 via 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, whereby the heat of the heat exchange type precooler 21 is utilized. One part of the purified chlorine gas that is 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.

Next, 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 and The on-off valve 23n of the pressure increasing pipe 23i is opened, and one part of the purified argon gas flowing out of the first adsorption tower 23 is introduced into the second adsorption tower 23 via the cooling/boosting pipe 23i. Thereby, the purified argon gas 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 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 for returning the heat medium from the heat exchange unit 24 to the heat medium supply source 24d is returned. Switch 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 the refrigerant circulation state. The refrigerant circulation state continues until the next pressure rising step and the subsequent adsorption step ends.

Next, 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 a part of the purified argon gas flowing out from the first adsorption tower 23 is introduced, whereby the second adsorption tower 23 is 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 column 23, the desorption step, the cleaning step, the cooling step, the pressure increasing step, and the second adsorption column 23 are similarly performed in the first 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, and may be three or four.

According to the 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 set to be smaller than the sum of the carbon monoxide molar concentration and the hydrogen molar concentration. 1/2, secondly, using a catalyst that reacts carbon monoxide with oxygen in preference to the reaction of hydrogen and oxygen, the oxygen in the argon is reacted with carbon monoxide and hydrogen, thereby generating carbon dioxide and water in a state of residual hydrogen, and thereafter The adsorbent can be used to reduce the content of impurities in the argon gas. Thereby, hydrogen which is less likely to remain in the residual state is actively retained, and in the case of adsorption removal, complete combustion of oxygen which increases the cooling energy can be achieved. Further, there is no need to make it possible to reduce the catalyst function and to more actively adsorb carbon monoxide than carbon dioxide. Thereby, the management of the purification apparatus is facilitated, and miniaturization can be achieved, thereby reducing energy consumption. Further, when the adsorbent is used to reduce the content of impurities in the argon gas, at least carbon dioxide and water in the impurities are adsorbed by a pressure swing adsorption method at a normal temperature, and then, by -10 ° C to -50 ° C The variable temperature adsorption method adsorbs at least nitrogen in the impurities, so that carbon dioxide, water, and nitrogen can be efficiently adsorbed. Further, by setting the oxygen molar concentration in the argon gas to a value exceeding 1/2 of the carbon monoxide molar concentration, it is possible to achieve complete combustion of one of the carbon oxides which has a function of reducing the catalyst. Further, when the oxygen molar concentration in the argon gas is set, hydrogen is added when the oxygen molar concentration is 1/2 or more of the sum of the carbon monoxide molar concentration and the hydrogen molar concentration, and the oxygen molar concentration is carbon monoxide. When the concentration of the ear is less than or equal to 1/2, oxygen is added, whereby since carbon monoxide is not added, the reaction product of carbon monoxide and water can be prevented from lowering the purity of argon gas.

Example

The argon recovered from the polycrystalline cast furnace was purified using the above purification apparatus α. The argon gas contained 3000 mol of nitrogen, 550 mol of oxygen, 200 mol of hydrogen, 1000 mol of carbon monoxide, and 10 mol of carbon dioxide as impurities. The chlorine gas was pressurized to 0.05 MpaG by a blower 7, and introduced into the heater 2 at a flow rate of 200 Nm ³ /h, and the temperature was controlled to 250 ° C, and introduced into the reactor 3. The reactor 3 was a cylindrical shape having a diameter of 400 mm and a length of 1200 mm, and was filled with a platinum catalyst (DASH-220 manufactured by NE Chemcat Co., Ltd.) carried by alumina. By the reaction in the reactor 3, the impurity concentration of the argon gas is: nitrogen is 3000 mol ppm, oxygen is 1 mol ppm or less, hydrogen is 100 mol ppm, carbon monoxide is 1 mol ppm or less, and carbon dioxide is 1010. MoM ppm, moisture is 100 mol ppm.

The argon gas is cooled to 40° C. by the cooler 5 configured by a water-cooled cooler, and then introduced into one adsorption tower 13 of the PSA unit 10 via the compressor 12 . Each of the adsorption towers 13 has a cylindrical shape of 600 mm in diameter and 1800 mm in length, and is filled with CaA type zeolite (5AHP manufactured by Union Showa Co., Ltd.) as an adsorbent. Each of the adsorption towers 13 was subjected to one cycle of a pressure increasing step, an adsorption step, a cleaning step, and a desorption step in 800 seconds. The argon gas is boosted to 0.8 MPaG by the compressor 12. The flow rate of the argon gas flowing out from the PSA unit 10 becomes 120 Nm ³ /h, and the impurity concentration in the argon becomes: 150 mol ppm of nitrogen, 0.1 mol ppm or less of oxygen, 100 mol ppm of hydrogen, and 0.5 mol of carbon monoxide. The molar amount of water and carbon dioxide is 0.5 mol or less and the dew point is -70 ° C or less.

After the argon gas purified by the PSA unit 10 is cooled in the precooler 21 and the cooler 22, it is introduced into one adsorption tower 23 of the TSA unit 20. Each of the adsorption towers 23 has a cylindrical shape with a diameter of 900 mm and a length of 1500 mm, and has 50 inner tubes filled with CaX-type zeolite (SA600A manufactured by TOSOH Co., Ltd.) as an adsorbent. The argon gas passing through an inner tube was cooled to -35 ° C by a heat exchanger 24, and the argon gas passing through the other inner tube was heated to 40 ° C. The flow rate of the argon gas flowing out from the TSA unit 20 becomes 110 Nm ³ /h, and the impurity concentration in the argon gas is: 0.1 mol or less of nitrogen, 0.1 mol ppm or less of oxygen, 110 mol ppm of hydrogen, and carbon monoxide. It is 0.5 mol ppm or less, carbon dioxide is 0.5 mol ppm or less, and the dew point is -70 ° C or less, so that substantially impurities are only hydrogen.

The present invention is not limited to the above embodiments or examples. For example, when it is desired to reduce the concentration of hydrogen in the argon gas purified by the present invention, a hydrogen removing device 30 as shown by a broken line in Fig. 1 may be provided. The hydrogen removal device 30 may be configured by separating a argon gas and a hydrogen gas by a gas separation membrane having a hydrogen permeability such as a polyimide membrane, or a metal oxide containing copper, nickel, or the like. In the reactor of the medium, the metal oxide is reacted to remove hydrogen. Further, the water generated by the reaction of the metal oxide and hydrogen is removed by, for example, filling a downstream side of the catalyst with a moisture absorbent such as an alumina gel or a zeolite. The hydrogen removal device 30 may be disposed downstream of the TSA unit 20 as shown in FIG. 1 or may be disposed between the PSA unit 10 and the TSA unit 20. A cylindrical reactor having a diameter of 300 mm is disposed downstream of the TSA unit 20, and the catalyst is filled with a catalyst having a main component of copper oxide, and argon gas purified by the above embodiment is passed, and then, The flow rate of argon gas is 110 Nm ³ /h, and the impurity concentration in argon is: 0.1 mol or less of nitrogen, 0.1 mol% or less of oxygen, 0.5 mol% or less of hydrogen, and 0.5 mol ppm of carbon monoxide. Hereinafter, the carbon dioxide was 0.5 mol ppm or less, and the dew point was -70 ° C or less, and the removal of hydrogen was confirmed. By providing such a hydrogen removing device 30, it is also possible to respond to the demand for reducing the hydrogen contained in the argon gas.

1. . . Argon supply

2. . . Heater and

3. . . reactor

4. . . Concentration adjusting device

4a. . . Concentration tester

4b. . . Hydrogen supply source

4c. . . Hydrogen regulator

4d. . . Oxygen supply

4e. . . Oxygen regulator

4f. . . Controller

5. . . Cooler

6. . . Adsorption device

7. . . Blower

10. . . PSA unit

12. . . compressor

13,23. . . Adsorption tower

13a. . . Entrance of adsorption tower 13

13b, 13e, 13l, 13n, 13p, 13x. . . Switching valve

13f. . . silencer

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

13m, 23g. . . Outflow piping

13o. . . Boost piping

13q. . . Pressure equalization ‧ clean out side piping

13r, 13u. . . Flow control valve

13s. . . Pressure equalization ‧ clean side piping

13t. . . A pressure regulating valve

13v. . . Flow indicator regulator

13w. . . Connecting piping

20. . . TSA unit

twenty one. . . Precooler

twenty two. . . Cooler

23a. . . Entrance to adsorption tower 23

23b, 23c, 23f, 23h, 23j, 23n, 24f. . . Switch valve

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

23i. . . Cooling and 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

30. . . Hydrogen removal device

α. . . Purification device

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

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

Fig. 3 is a block diagram showing the configuration of a 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. . . Hydrogen supply source

4c. . . Hydrogen regulator

4d. . . Oxygen supply

4e. . . Oxygen regulator

4f. . . Controller

5. . . Cooler

6. . . Adsorption device

7. . . Blower

10. . . PSA unit

20. . . TSA unit

30. . . Hydrogen removal device

α. . . Purification device

Claims (3)

A method 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 the oxygen molar concentration in the argon gas is set to be less than a carbon monoxide molar concentration. 1/2 of the sum of the hydrogen molar concentration and a value of 1/2 of the molar concentration of carbon monoxide; when setting the oxygen molar concentration in the above argon gas, the oxygen molar concentration is the carbon monoxide molar concentration and the hydrogen molar Add hydrogen when the sum of the ear concentrations is 1/2 or more, and add oxygen when the oxygen molar concentration is less than 1/2 of the molar concentration of carbon monoxide; secondly, use the reaction of carbon monoxide with oxygen over hydrogen and oxygen. a reaction catalyst for reacting oxygen in the argon gas with carbon monoxide and hydrogen to generate carbon dioxide and water in a state of residual hydrogen; thereafter, using an adsorbent to reduce the content of impurities in the argon gas; The medium contains platinum as a main component. The method for purifying argon according to claim 1, wherein when the content of the impurity in the argon gas is lowered by using the adsorbent, the at least carbon dioxide and water in the impurity are adsorbed by a pressure swing adsorption method at normal temperature. At least nitrogen in the impurities is adsorbed by a temperature swing adsorption method at -10 ° C to -50 ° C. 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 which is introduced into the argon gas; a concentration adjusting device that sets an oxygen molar concentration in the argon gas introduced into the reactor to be less than 1/2 of a sum of a carbon monoxide molar concentration and a hydrogen molar concentration and more than 1/2 of a carbon monoxide molar concentration And a adsorption device connected to the reactor; and when the oxygen molar concentration in the argon gas is set, the oxygen molar concentration is 1/2 or more of the sum of the carbon monoxide molar concentration and the hydrogen molar concentration. In the case where hydrogen is added, oxygen is added when the oxygen molar concentration is less than or equal to 1/2 of the carbon monoxide molar concentration; and the catalyst which reacts carbon monoxide with oxygen in preference to the reaction of hydrogen and oxygen is filled in the above reactor. So that carbon dioxide and water are generated in a state of residual hydrogen by reacting oxygen in the argon gas in the reactor with carbon monoxide and hydrogen; the adsorption device includes an adsorbent for reducing the above-mentioned flow from the reactor The content of impurities in argon gas; the above catalyst contains platinum as a main component.