JP2012082080A - Argon refining method and argon refining apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and an apparatus suitable for obtaining high purity argon with a high recovery rate while reducing energy which gas purification takes.SOLUTION: The method includes: a PSA gas separation step which performs a cycle including: a pretreatment process which makes an argon gas Gcontaining impurity contact a ruthenium catalyst; an adsorption process which adsorbs the impurity of a gas Gwhich has passed through the pretreatment to an adsorbent by a PSA method, and derives a semi-purified gas Gin which argon has been enriched; a desorption process which desorbs the impurity from the adsorbent, and derives the gas inside a column; and a pressure equalization process which pressure-equalizes the internal pressure between an adsorption column which has passed through the adsorption process and the adsorption column which passed through the desorption process; and a TSA gas separation step which performs a cycle including: an adsorption process by a TSA method in which an adsorbent introduces the semi-purified gas Gin the state of a low temperature, and adsorbs the impurity to the adsorbent, and derives a purified gas Gfrom the semi-purified gas G; and a regeneration process which desorbs the impurity from the adsorbent while rising the temperature of the adsorbent, and derives the gas inside the column.

Description

  The present invention relates to a method and an apparatus for purifying argon using a pressure fluctuation adsorption method and a temperature fluctuation adsorption method.

  Argon is often used as an atmospheric gas in a silicon single crystal pulling furnace, a ceramic sintering furnace, a vacuum degassing furnace for steel making, a silicon plasma melting furnace for solar cells, and the like. The purity of argon used as the atmosphere gas in the furnace is lowered due to mixing of impurities such as hydrogen, carbon monoxide, and air (mainly nitrogen and oxygen). The argon used as the furnace atmosphere gas may be purified by adsorbing the mixed impurities on the adsorbent for reuse. Furthermore, in order to efficiently adsorb such impurities, it has been proposed to react oxygen in the impurities with combustible components as pretreatment of the adsorption treatment (see, for example, Patent Documents 1 and 2).

  In the method disclosed in Patent Document 1, the amount of oxygen in the mixed gas containing argon and impurities is slightly less than the stoichiometric amount necessary for complete combustion of combustible components such as hydrogen and carbon monoxide. Adjust so that Next, by using palladium or gold, which gives priority to the reaction between hydrogen and oxygen over the reaction between carbon monoxide and oxygen, the oxygen in the mixed gas is reacted with carbon monoxide, hydrogen, etc. Carbon dioxide and water are produced in the state of remaining. Next, carbon dioxide and water contained in the mixed gas are adsorbed on the adsorbent at room temperature by the pressure fluctuation adsorption method (PSA method), and the non-adsorbed gas is discharged. Thereafter, carbon monoxide and nitrogen contained in the non-adsorbed gas are adsorbed on the adsorbent at a temperature of −10 ° C. to −50 ° C. by the temperature fluctuation adsorption method (TSA method), and the gas not adsorbed here. Is obtained as purified gas. When regenerating an adsorbent that adsorbs carbon monoxide and nitrogen at such a low temperature, carbon monoxide is industrially disadvantageous because it requires more energy to desorb from the adsorbent than nitrogen.

  In the method disclosed in Patent Document 2, the amount of oxygen in the mixed gas is set to an amount sufficient for complete combustion of combustible components such as hydrogen and carbon monoxide. Next, carbon dioxide and water are produced with oxygen remaining by reacting oxygen in the mixed gas with carbon monoxide, hydrogen, or the like using a palladium-based catalyst. Next, carbon dioxide and water contained in the mixed gas are adsorbed on the adsorbent at room temperature, and the non-adsorbed gas is discharged. Thereafter, oxygen and nitrogen contained in the non-adsorbed gas are adsorbed on the adsorbent at a temperature of about −170 ° C. by the TSA method, and the gas not adsorbed here is obtained as a purified gas. In order to adsorb oxygen by the TSA method (temperature fluctuation adsorption method), it is necessary to lower the gas temperature during adsorption to about -170 ° C. That is, since oxygen remains in the pretreatment of the adsorption treatment, there is a problem that the cooling energy during the adsorption treatment increases and the purification load increases.

Japanese Patent No. 3496079 Japanese Patent No. 3737900

  The present invention has been conceived under such circumstances, and in purifying argon gas containing impurities, high purity argon can be obtained at a high recovery rate while reducing energy required for gas purification. It is an object of the present invention to provide a method and apparatus suitable for the above.

  The argon purification method provided by the first aspect of the present invention is a method for concentrating and purifying argon from an argon gas containing at least oxygen, carbon monoxide, hydrogen and nitrogen as impurities, wherein the argon gas is converted into a ruthenium catalyst. A pretreatment step of contacting carbon monoxide and hydrogen contained in the argon gas with oxygen to react with oxygen to change carbon dioxide and water to substantially remove the carbon monoxide and hydrogen, and PSA adsorption In the state where the PSA adsorption tower is at a relatively high pressure, the PSA adsorption tower is subjected to the pretreatment step by the pressure fluctuation adsorption method using three or more PSA adsorption towers filled with the agent. A mixed gas from which carbon oxides and hydrogen have been removed is introduced, and the impurities in the mixed gas are adsorbed on the PSA adsorbent, and are absorbed from the PSA adsorption tower. PSA adsorption step for deriving semi-purified gas enriched with gon, desorption step for desorbing impurities from the PSA adsorbent by depressurizing the PSA adsorption column, and deriving gas from the PSA adsorption column, PSA adsorption column In order to equalize the internal pressure of the PSA adsorption tower which passed through the washing process which introduce | transduces cleaning gas into the PSA adsorption tower which passed through the said adsorption process, and the PSA adsorption tower which passed through the said adsorption process The TSA adsorbent in the TSA adsorption tower is obtained by a pressure fluctuation type gas separation step in which a cycle including the pressure equalization step is repeated and a temperature fluctuation adsorption method using a TSA adsorption tower filled with the TSA adsorbent. At the low adsorption temperature, the semi-purified gas is introduced into the TSA adsorption tower so that impurities in the semi-purified gas are adsorbed on the TSA adsorbent, and from the TSA adsorption tower, A TSA adsorption process for deriving a purified gas enriched in argon from the semi-purified gas, and desorbing impurities from the TSA adsorbent while raising the TSA adsorbent in the TSA adsorption tower to a high temperature. And a temperature fluctuation adsorption type gas separation step in which a cycle including a regeneration step of regenerating the TSA adsorbent by deriving off-gas from the TSA adsorption tower is repeated.

  Preferably, the mixed gas before the pretreatment is adjusted such that the oxygen molar concentration in the mixed gas exceeds 1/2 of the sum of the molar concentration of carbon monoxide and the molar concentration of hydrogen.

  Preferably, the pressure equalization step in the pressure fluctuation type gas separation step is performed such that the first gas is led out from the PSA adsorption tower that has undergone the adsorption step from the start to the middle of the pressure equalization step and the internal pressure of the PSA adsorption column is increased. A first pressure equalizing step in which the first pressure is lower than the adsorption pressure, and the second gas is derived from the PSA adsorption tower and the internal pressure of the PSA adsorption tower is set to a second pressure lower than the first pressure. A second pressure equalization step after the first pressure equalization step, and in the second pressure equalization step, the second gas is introduced into the PSA adsorption tower that has undergone the washing step, and the internal pressure of the PSA adsorption tower is increased. In the first pressure equalizing step, the first gas is introduced into the PSA adsorption tower whose internal pressure has been increased to the second pressure through the second pressure equalizing step, and the PSA Increase the internal pressure of the adsorption tower to the first pressure That.

  Preferably, the PSA is performed after the cleaning step and before the second pressure equalizing step, and by blocking gas flow into and out of the PSA adsorption tower in a relatively low pressure state after the cleaning step. A recovery step for recovering the gas by desorbing the gas from the PSA adsorbent in the adsorption tower is further provided.

  Preferably, the PSA adsorbent includes a carbon molecular sieve.

  Preferably, the TSA adsorption tower is provided with an adsorption tube filled with the TSA adsorbent therein, and in the TSA adsorption step, the liquid refrigerant is passed through the TSA adsorption tower, thereby the TSA adsorbent. In the regeneration step, the TSA adsorbent is heated by passing a liquid heat medium through the TSA adsorption tower.

  Preferably, the adsorption temperature in the TSA adsorption step is −50 to −10 ° C.

  An argon purification apparatus provided by the second aspect of the present invention is an apparatus for concentrating and purifying argon from an argon gas containing at least oxygen, carbon monoxide, hydrogen and nitrogen as impurities. Pressure fluctuation adsorption performed using a pretreatment device for contacting carbon monoxide and hydrogen contained in the argon gas with oxygen by contacting with a ruthenium catalyst and three or more PSA adsorption towers packed with a PSA adsorbent. In the state where the PSA adsorption tower is at a relatively high pressure, a mixed gas from which carbon monoxide and hydrogen have been removed through the pretreatment step is introduced into the PSA adsorption tower. A PSA adsorption process for adsorbing impurities on the PSA adsorbent and deriving a semi-purified gas enriched with argon from the PSA adsorption tower; Desorption step of desorbing impurities from the PSA adsorbent and deriving gas from the PSA adsorption tower, cleaning step of deriving gas from the PSA adsorption tower while introducing a cleaning gas into the PSA adsorption tower, and Pressure fluctuation adsorption gas separation configured to repeatedly perform a cycle including an internal pressure of the PSA adsorption tower that has undergone the adsorption process and a pressure equalization process for equalizing the internal pressure of the PSA adsorption tower that has undergone the washing process. The TSA adsorption tower is in a state where the TSA adsorbent in the TSA adsorption tower is at a low adsorption temperature by an apparatus and a temperature fluctuation adsorption method performed using a TSA adsorption tower filled with the TSA adsorbent. A semi-purified gas is introduced so that impurities in the semi-purified gas are adsorbed on the TSA adsorbent. A TSA adsorption step for deriving gas, and desorbing impurities from the TSA adsorbent while raising the TSA adsorbent in the TSA adsorption tower to a high temperature, thereby deriving off-gas from the TSA adsorption tower A temperature fluctuation adsorption gas separation device configured to repeatedly perform a cycle including a regeneration step of regenerating the TSA adsorbent.

  In the second aspect of the present invention, preferably, the TSA adsorption tower has a first gas passage port and a second gas passage port, communicates with the first and second gas passage ports, and the TSA adsorbent. The temperature fluctuation adsorption gas separation device includes a refrigerant storage tank for holding a liquid refrigerant to be supplied to the TSA adsorption tower in order to cool the TSA adsorbent in the adsorption tube. A heating medium storage tank for holding a liquid heat medium supplied to the TSA adsorption tower for heating the TSA adsorbent in the adsorption pipe; and supplying the refrigerant from the refrigerant storage tank to the TSA adsorption tower. A first refrigerant line, a second refrigerant line for returning the refrigerant from the TSA adsorption tower to the refrigerant storage tank, and a first for supplying the heat medium from the heat medium storage tank to the TSA adsorption tower. With heat transfer line And a second heat medium line for returning the heat medium in the heat medium storage tank from the TSA adsorption tower.

  According to the argon purification method of the present invention, the pretreatment, the pressure fluctuation adsorption method (PSA method), and the temperature fluctuation adsorption method (TSA method) described above are executed, whereby high purity of argon is achieved. It is easy to achieve a high recovery rate while reducing the energy for obtaining argon (purified gas). In the pretreatment of this method, carbon monoxide and hydrogen contained as impurities in the argon gas are reacted with oxygen using a ruthenium catalyst. The ruthenium catalyst has an ability to react with carbon monoxide and hydrogen over other platinum-based catalysts and the like, and can completely convert carbon monoxide and hydrogen into other compounds. Further, according to the ruthenium catalyst, the ambient temperature (reaction temperature) necessary for the reaction may be lower than that of the other catalyst, which contributes to the reduction of energy for heating the argon gas in the pretreatment.

  Further, in the gas purification by the PSA method of the present method, the gas in the PSA adsorption tower after the PSA adsorption step has a relatively high argon concentration (similar to the semi-purified gas), but such an argon concentration is high. In the pressure equalization process, the gas is introduced into another PSA adsorption tower that has undergone the cleaning process, so that the other PSA adsorption tower is pressurized to prepare for the PSA adsorption process. Therefore, the gas having a high argon concentration introduced into the other PSA adsorption tower is taken out as a semi-purified gas in the subsequent PSA adsorption step without being discharged out of the apparatus, and is subjected to gas purification by the next TSA method. Is done. Therefore, this method is suitable for obtaining high purity argon with a high recovery rate.

  Other features and advantages of the present invention will become more apparent from the detailed description given below with reference to the accompanying drawings.

It is a whole schematic block diagram of the argon purification apparatus which concerns on this invention. It is a block diagram of the PSA gas separation apparatus which is a part of the argon purification apparatus which concerns on this invention. It is a figure which shows an example of the process (steps 1-9) performed by each PSA adsorption tower in the PSA gas separation process performed with the PSA gas separation apparatus shown in FIG. 2, and the open / close state of each valve in each step. . It is a figure showing the gas flow state in steps 1-9 shown in FIG. It is a figure showing the change of the internal pressure of each PSA adsorption tower in steps 1-9 shown in FIG. It is a block diagram of the TSA gas separation apparatus which is a part of the argon purification apparatus which concerns on this invention. It is a figure which shows the opening / closing state of each valve in each process (step 1-6) performed in each TSA adsorption tower in the TSA gas separation process performed with the TSA gas separation apparatus shown in FIG. The PSA gas separation process performed by the PSA gas separation device shown in FIG. It is. It is a figure showing the gas flow state in steps 1-9 shown in FIG. It is a figure showing the change of the internal pressure of each PSA adsorption tower in steps 1-9 shown in FIG. It is the table | surface which put together the Example and comparative example of this invention. It is the table | surface which put together the Example and comparative example of this invention.

  Hereinafter, as a preferred embodiment of the present invention, a method for concentrating and separating argon from a source gas containing argon will be specifically described with reference to the drawings.

  FIG. 1 shows a schematic configuration of an argon purification apparatus that can be used to execute the argon purification method according to the present embodiment. The argon purification device X includes a concentration adjusting device 1, a heater 2, a reactor 3, a cooler 4, a compressor 5, a dehydrator 6, a line 7, and an adsorption device 8. Argon can be continuously purified while supplying the source gas (argon gas) containing it.

The source gas G ₀ is argon which is used as an atmosphere gas in a furnace in a silicon crystal pulling furnace, a ceramic sintering furnace, a vacuum degassing furnace for steel making, a silicon plasma melting furnace for solar cells, and the like, and impurities are mixed therein. , Discharged continuously or intermittently from at least one predetermined furnace (not shown). The discharge flow rate, pressure, and composition of the exhaust gas (raw material gas G ₀ ) often vary depending on the process being performed in the furnace and the operating conditions of the furnace, and may vary rapidly. The source gas G ₀ is dust-proofed by a filter (not shown) (not shown), and is introduced into the line 7 through the source gas introduction end E 1 via a gas feed means (not shown) such as a blower. The source gas G ₀ includes, for example, argon as a main component and oxygen, carbon monoxide, hydrogen, nitrogen, and water as impurities. It may also contain other impurities such as carbon dioxide and hydrocarbons. The main impurity is, for example, nitrogen. The concentration of impurities in the raw material gas G ₀ is not particularly limited, and is, for example, about 5 mol ppm to 40000 mol ppm (4 mol%), but depending on the gas feeding means, air may be mixed in, and the impurity concentration In some cases, it may be contained up to about 30 mol%.

The concentration controller 1, the heater 2, the reactor 3, the cooler 4, the compressor 5, and the dehydrator 6 are arranged in series in the line 7. The concentration adjusting device 1 is for adding oxygen to the raw material gas G ₀ as necessary, and is connected to the line 7. The concentration adjusting device 1 includes, for example, a concentration analyzer that measures the concentration of each impurity, an oxygen storage unit, and a valve that can control the opening degree and the open state time. The flow rate of supplied oxygen is controlled as necessary. Such a concentration control device 1 is provided in the raw material gas G ₀ when the oxygen molar concentration in the raw material gas introduced into the reactor 3 is not more than ½ of the sum of the carbon monoxide molar concentration and the hydrogen molar concentration. Add a fixed amount of oxygen. By adding oxygen, the oxygen molar concentration in the raw material gas G ₀ introduced into the reactor 3 is adjusted to a value exceeding 1/2 of the sum of the carbon monoxide molar concentration and the hydrogen molar concentration.

The heater 2 is for raising the temperature of the raw material gas G ₀ before being introduced into the reactor 3, and is composed of, for example, an electric heater. The heating temperature of the raw material gas G ₀ by the heater 2 is preferably 100 ° C. or higher in order to complete the reaction in the reactor 3, and is preferably 300 ° C. or lower from the viewpoint of preventing the catalyst life from being shortened.

The reactor 3 is for substantially removing carbon monoxide and hydrogen by changing oxygen in the raw material gas G ₀ to carbon dioxide and water by reacting with carbon monoxide and hydrogen, respectively. . The reactor 3 is packed with a catalyst that promotes the conversion reaction represented by the following reaction formulas (1) and (2). A ruthenium catalyst can be employed as the catalyst. Ruthenium catalyst is superior to other platinum-based catalysts in the ability to react with carbon monoxide and hydrogen, and carbon monoxide and hydrogen contained as impurities in source gas G ₀ can be completely transformed into other compounds. preferable. The ruthenium catalyst is also far superior to other platinum-based catalysts in the ability to react carbon monoxide and hydrogen to methanation. If a ruthenium catalyst is used, the ruthenium catalyst is expressed by the following reaction formula (3). Reaction is also promoted. Therefore, the use of such a ruthenium catalyst is preferable for completely transforming carbon monoxide and hydrogen contained as impurities in the raw material gas G ₀ into other compounds. As the ruthenium catalyst actually used, a ruthenium supported by a carrier such as alumina can be used. Moreover, as a catalyst with which the reactor 3 is filled, although only a ruthenium catalyst may be used, it is possible to use a plurality of types including a ruthenium catalyst and at least one other platinum-based catalyst (platinum catalyst, palladium catalyst, etc.). A catalyst may be used.

When the raw material gas G ₀ is introduced into the reactor 3, oxygen in the raw material gas G ₀ reacts with carbon monoxide and hydrogen by the action of the catalyst, and carbon dioxide and water are generated in a state where oxygen remains. . In this way, the gas G ₁ (mixed gas) from which carbon monoxide and hydrogen have been substantially removed is led out from the reactor 3. The raw material gas G ₀ discharged from a silicon crystal pulling furnace or the like may contain hydrocarbons as combustible components. The molar concentration of the hydrocarbon is usually 1/100 of the total molar concentration of carbon monoxide and hydrogen. It is as follows. Therefore, if the oxygen molar concentration is usually set by the concentration adjusting device 1 so that it slightly exceeds 1/2 of the sum of the carbon monoxide molar concentration and the hydrogen molar concentration with respect to the raw material gas G ₀ , Carbon dioxide and water are produced in a state where hydrocarbons are substantially removed by combustion and oxygen remains. Further, even if hydrocarbons remain in the gas G ₁ that has passed through the reactor 3, it is easy to remove by adsorption by a subsequent PSA gas separation device. Therefore, it is not necessary to consider the hydrocarbon concentration when adjusting the oxygen molar concentration by the concentration adjusting device 1.

The cooler 4 is for cooling the gas G ₁ led out from the reactor 3, and is composed of, for example, a heat exchanger using cooling water as a cooling medium. The temperature of the gas G ₁ that has passed through the cooler 4 is, for example, about 20 to 40 ° C. In addition, said heater 2, reactor 3, and cooler 4 are apparatuses (henceforth a "pretreatment apparatus") which bear the pretreatment process of this invention method. The pretreatment device may adopt a different configuration from that described above according to the type and amount of impurities to be removed before supplying the gas G ₁ to the adsorption device 8 at the subsequent stage.

The compressor 5 is for sending the gas G ₁ flowing through the line 7 toward the adsorption device 8 at the subsequent stage while pressurizing the gas G ₁ .

The dehydrator 6 is for dehydrating the gas G ₁ supplied from the compressor 5 to reduce the moisture content of the gas G ₁ . The dehydrator 6 may be used commercially available ones, for example, a gas G ₁ pressing to remove moisture by adsorption agent, adsorbent pressurized dewatering apparatus for reproducing under reduced pressure, the gas G ₁ and the pressurized cooling A refrigerating dehydrator that removes the condensed water, a heat regeneration dehydrator that removes moisture contained in the gas G ₁ with a dehydrating agent, and regenerates the dehydrating agent by heating can be used. A heat regeneration type dehydrator is preferable for effectively reducing the moisture content, and is preferably capable of removing about 99% of the moisture in the gas G ₁ . Note that the dehydrator 6 is not necessarily required when the moisture in the gas G ₁ led out from the reactor 3 is small, and is disposed below the three adsorption towers 11A, 11B, and 11C of the PSA gas separation device 10 described later. By filling a dehydrating agent (adsorbent) such as alumina gel, moisture removal can be sufficiently provided. If the water in the gas G ₁ derived from the reactor 3 is large and is a case where air in the raw material gas G ₀ is mixed, for example, the raw material gas G ₀ when air is mixed 20 mol%, oxygen 4 mol % Mixed. If this is reacted with hydrogen, 8 mol% of water is by-produced. In such a case, the dehydrator 6 is essential. When air mixing is 1 mol% or more, it is better to use the dehydrator 6.

  The adsorption device 8 includes a pressure fluctuation adsorption gas separation device (PSA gas separation device) 10 and a temperature fluctuation adsorption gas separation device (TSA gas separation device) 20 arranged in series, and a line connected to these. Yes.

As shown in FIG. 2, the PSA gas separation apparatus 10 includes three adsorption towers 11A, 11B, and 11C (PSA adsorption towers) and a plurality of lines 12 to 17 that form gas flow paths. Argon is concentrated and separated from the gas G _{1 using a} pressure fluctuation adsorption method (PSA method).

Each of the adsorption towers 11A, 11B, and 11C has gas passage ports 11a and 11b at both ends, and an adsorbent for selectively adsorbing impurities contained in the gas G ₁ between the gas passage ports 11a and 11b. (PSA adsorbent) is filled. For example, zeolite can be used as an adsorbent for adsorbing nitrogen, carbon monoxide, and carbon dioxide as impurities. For example, a carbon molecular sieve can be used as an adsorbent for adsorbing oxygen, carbon dioxide, and methane as impurities. For example, alumina gel can be used as an adsorbent for adsorbing moisture as impurities. One kind of adsorbent may be filled in the adsorption towers 11A, 11B, and 11C, or plural kinds of adsorbents may be stacked and filled in the adsorption towers 11A, 11B, and 11C. The type and number of adsorbents packed in the adsorption towers 11A, 11B, and 11C are determined according to the type and amount of impurities to be removed in the adsorption towers 11A, 11B, and 11C. In the present embodiment, the oxygen contained in the gas G ₁ which has undergone a pretreatment in order to efficiently remove, as the adsorbent, carbon molecular sieve is preferably used.

  The gas passage ports 11a of the adsorption towers 11A, 11B, and 11C are connected to the line 12 via the branch paths 12A, 12B, and 12C. The branch paths 12A, 12B, and 12C are provided with automatic valves 12a, 12b, and 12c that can switch between an open state and a closed state.

  The gas passage ports 11a of the adsorption towers 11A, 11B, and 11C are also connected to the off gas line 13 via the branch paths 13A, 13B, and 13C. Automatic valves 13a, 13b, and 13c are provided in the branch paths 13A, 13B, and 13C. A silencer 13d is provided at the end of the off-gas line 13, and the end of the off-gas line 13 is open to the atmosphere via the silencer 13d.

  The gas passage ports 11a of the adsorption towers 11A, 11B, and 11C are further connected to the lower pressure equalization line 14 via branch paths 14A, 14B, and 14C. Automatic valves 14a, 14b, and 14c are provided in the branch paths 14A, 14B, and 14C.

  The gas passage ports 11b of the adsorption towers 11A, 11B, and 11C are connected to the semi-purified gas line 15 via the branch paths 15A, 15B, and 15C. Automatic valves 15a, 15b, and 15c are provided in the branch paths 15A, 15B, and 15C. The semi-purified gas line 15 is provided with a pressure equalizing tank 15d and a pressure adjusting valve 15e. The pressure regulating valve 15e is for controlling the inside of each adsorption tower 11A, 11B, 11C to a desired adsorption pressure. The end of the semi-purified gas line 15 is connected to a line 22a of a TSA gas separation device 20 described later.

  The gas passage ports 11b of the adsorption towers 11A, 11B, and 11C are also connected to the cleaning line 16 via branch paths 16A, 16B, and 16C. Automatic valves 16a, 16b, and 16c are provided in the branch paths 16A, 16B, and 16C. The cleaning line 16 is branched in the middle of the semi-purified gas line 15 and is used for introducing a part of the semi-purified gas led out from the gas passage port 11b into any adsorption tower as a cleaning gas. It is. The cleaning line 16 is provided with a check valve 16d, a flow meter 16e, and a flow control valve 16f.

  The gas passage ports 11b of the adsorption towers 11A, 11B, and 11C are further connected to the upper pressure equalization line 17 via branch paths 17A, 17B, and 17C. Automatic valves 17a, 17b, and 17c are provided in the branch paths 17A, 17B, and 17C.

  In the PSA gas separation apparatus 10 configured as described above, the flow direction and pressure of the gas in the adsorption towers 11A, 11B, and 11C are adjusted by appropriately switching the open / closed state of each automatic valve provided in the line or branch path. Is done. In the PSA gas separation line process performed using the PSA gas separation apparatus 10, a cycle including, for example, an adsorption process, a desorption process, a cleaning process, and a pressure equalization process is repeated in each of the adsorption towers 11A, 11B, and 11C. It is.

  In the adsorption step, the mixed gas is introduced into any of the adsorption towers in a predetermined high pressure state, and impurities (oxygen, carbon dioxide, nitrogen, water, etc.) in the mixed gas are adsorbed by the adsorbent, This is a process for deriving non-adsorbed gas (semi-purified gas) enriched with argon from the adsorption tower. The desorption process is a process for depressurizing any of the adsorption towers that have completed the adsorption process to desorb impurities from the adsorbent, and leading out the gas in the tower to the outside as an off-gas. The cleaning process is a process for introducing the gas in the tower as an off-gas to the outside of the tower while introducing a gas having a high argon concentration (for example, semi-purified gas) derived from another adsorption tower as the cleaning gas. In the pressure equalization process, for example, one of the adsorption towers that have finished the adsorption process and the other adsorption tower that has finished the washing process are communicated, and a gas flow is generated between the two adsorption towers due to a pressure difference in the two adsorption towers. This is a step for equalizing the internal pressure of both adsorption towers. In the pressure equalization process, the adsorption tower that has a relatively high pressure at the start of the pressure equalization process (adsorption tower that has finished the adsorption process) is depressurized, and the adsorption tower that has a relatively low pressure at the start of the pressure equalization process (washing) The adsorption tower after finishing the process is pressurized.

  In the argon purification method according to the present embodiment, the semi-purified gas enriched with argon is separated from the mixed gas using the PSA gas separation device 10. Specifically, by switching the automatic valves 12a to 12c, 13a to 13c, 14a to 14c, 15a to 15c, 16a to 16c, and 17a to 17c in the mode shown in FIG. For example, one cycle consisting of the following steps 1 to 9 can be repeated. In FIG. 3, the open state of each automatic valve is represented by a circle and the closed state is represented by a cross. In one cycle of this method, in each of the adsorption towers 11A, 11B, and 11C, an adsorption process, a first pressure equalization (decompression) process, a second pressure equalization (decompression) process, a desorption cleaning process, and a second pressure equalization ( A pressure increase) step, a standby, and a first pressure equalization (pressure increase) step are performed. FIG. 4 schematically shows the gas flow state in the PSA gas separation apparatus 10 in steps 1 to 9. FIG. 5 shows a change in the internal pressure of each adsorption tower 11A, 11B, 11C in steps 1-9.

  In step 1, the open / close state of each automatic valve is selected as shown in FIG. 3, the gas flow state as shown in FIG. 4A is achieved, and the adsorption process is performed in the adsorption tower 11A to the adsorption tower 11B. Thus, the second pressure equalization (pressure increase) step is performed in the adsorption tower 11C.

As can be well understood with reference to FIG. 3 and FIG. 4 (a), in step 1, gas G ₁ (mixed gas) is introduced to the gas passage 11a side of the adsorption tower 11A in a predetermined high pressure state. Impurities (carbon dioxide, water, nitrogen, etc.) in the gas G ₁ are adsorbed by the adsorbent in the adsorption tower 11A, and the semi-purified gas G ₂ enriched with argon is on the gas passage 11b side of the adsorption tower 11A. Is derived from The semi-purified gas G ₂ is sent to the TSA gas separation device 20 through the semi-purified gas line 15. In the adsorption tower 11B, the desorption cleaning process is performed first, and in the adsorption tower 11C, the first pressure equalization (decompression) process is performed first (see step 9 shown in FIG. 4 (i)). For this reason, at the start of step 1, the internal pressure of the adsorption tower 11B is a pressure as low as the desorption pressure, while the internal pressure of the adsorption tower 11C is higher than the internal pressure of the adsorption tower 11B (first pressure). It has become. Therefore, in step 1, the gas G ₄ (second gas) is led out from both sides of the gas passage ports 11a and 11b of the adsorption tower 11C, and the gas G ₄ is introduced into the adsorption tower 11B via the lines 14 and 17. . As a result, the inside of the adsorption tower 11B is increased in pressure, while the inside of the adsorption tower 11C is reduced in pressure, and at the end of step 1, the internal pressures of both the adsorption towers 11B and 11C both become the second pressure (see FIG. 5). ).

  In step 2, the open / close state of each automatic valve is selected as shown in FIG. 3, the gas flow state as shown in FIG. 4B is achieved, and the adsorption step is performed in the adsorption tower 11A to the adsorption tower 11B. Then, the desorption cleaning process is performed in the adsorption tower 11C.

As can be well understood with reference to FIGS. 3 and 4B, in step 2, the adsorption step is continued from step 1 in the adsorption tower 11A, and the semi-purified gas G ₂ is derived. As for the adsorption tower 11B, the automatic valves 12b, 13b, 14b, 15b, 16b, 17b provided in the branch paths 12B, 13B, 14B, 15B, 16B, 17B leading to the gas passage ports 11a, 11b are all closed. Therefore, the gas entry / exit is blocked and the apparatus enters a standby state. The inside of the adsorption tower 11B is maintained at substantially the same pressure (second pressure) as the second pressure at the end of the previous step 1. At the same time, in step 2, is introduced as a cleaning gas semi purified gas G ₂ of part cleaning line 16, the gas passage holes 11b of the adsorption tower 11C through a flow control valve 16f from the adsorption tower 11A. In the adsorption tower 11C, impurities are desorbed from the adsorbent, and the gas G ₅ is led out from the gas passage port 11a side as an off-gas so as to replace the cleaning gas introduced from the passage port 11b. The gas G ₅ is discharged out of the apparatus via the offgas line 13 and silencer 13d (in the air).

  In step 3, the open / close state of each automatic valve is selected as shown in FIG. 3, and the gas flow state as shown in FIG. 4C is achieved, and the first equalization (decompression) step in the adsorption tower 11A. However, the first pressure equalization (pressure increase) process is performed in the adsorption tower 11B, and the desorption cleaning process is performed in the adsorption tower 11C.

In the previous step 2, the adsorption step is performed in the adsorption tower 11A, and the adsorption tower 11B is set in a standby state. For this reason, at the start of step 3, the internal pressure of the adsorption tower 11A is as high as the adsorption pressure, while the internal pressure of the adsorption tower 11B is lower than the internal pressure of the adsorption tower 11A (second pressure). It has become. Accordingly, in step 3, the gas G ₃ (first gas) is led out from both sides of the gas passage ports 11a and 11b of the adsorption tower 11A, and the gas G ₃ is introduced into the adsorption tower 11B through the lines 14 and 17. . As a result, the inside of the adsorption tower 11B is increased in pressure, while the inside of the adsorption tower 11A is reduced in pressure, and at the end of step 3, the internal pressures of both the adsorption towers 11A and 11B both become the first pressure (see FIG. 5). ). At the same time, in step 3, the semi-purified gas G ₂ derived from the adsorption tower 11A in the previous step 2 and remaining in the semi-purified gas line 15 passes through the cleaning line 16 and the flow control valve 16f through the gas in the adsorption tower 11C. It is introduced as a cleaning gas into the mouth 11b side. In the adsorption tower 11C, and continues to desorb impurities from the adsorbent from step 2, gas G ₅ is derived as off-gas as replaced with the cleaning gas introduced from the passage opening 11b from the gas passage openings 11a side. The gas G ₅ is discharged out of the apparatus via the offgas line 13 and silencer 13d.

  In Steps 1 to 3, the maximum pressure (adsorption pressure) inside the adsorption tower 11A in the adsorption process of Steps 1 and 2 is, for example, 700 to 800 kPaG. The pressure (second pressure) inside the adsorption towers 11B and 11C at the end of the second pressure equalizing step in Step 1 is, for example, 200 to 250 kPaG. The pressure inside the adsorption tower 11B in the standby state in Step 2 is, for example, 200 to 250 kPaG. The pressure (first pressure) inside the adsorption towers 11 </ b> A and 11 </ b> B at the end of the first pressure equalization process in Step 3 is, for example, 400 to 450 kPaG. The minimum pressure (desorption pressure) inside the adsorption tower 11C in the desorption cleaning process over steps 2 to 3 is, for example, 0 to 30 kPaG.

  In steps 4 to 6, as in the adsorption tower 11A in steps 1 to 3, in the adsorption tower 11B, as shown in FIGS. 4 (d) to (f), the adsorption process (steps 4 and 5), A first pressure equalization (decompression) step (step 6) is performed. At the same time, in steps 4 to 6, the second equalization (pressure increase) is performed in the adsorption tower 11C as shown in FIGS. 4 (d) to (f) in the same manner as in the adsorption tower 11B in steps 1 to 3. ) Step, standby, and first pressure equalization (pressure increase) step are performed. At the same time, in steps 4 to 6, the second equalization (decompression) is performed in the adsorption tower 11A as shown in FIGS. ) Process (step 4) and desorption cleaning process (steps 5 and 6).

  In Steps 7 to 9, in the same manner as in the adsorption tower 11A in Steps 1 to 3, the adsorption process (Steps 7 and 8) in the adsorption tower 11C as shown in FIGS. A first pressure equalization (decompression) step (step 9) is performed. At the same time, in Steps 7 to 9, in the same manner as that performed in the adsorption tower 11B in Steps 1 to 3, in the adsorption tower 11A, as shown in FIGS. ) Step, standby, and first pressure equalization (pressure increase) step are performed. At the same time, in steps 7 to 9, the second equalization (decompression) is performed in the adsorption tower 11B as shown in FIGS. ) Process (step 7) and desorption cleaning process (steps 8 and 9).

As described above, the semi-purified gas G ₂ enriched with argon is continuously sent from the PSA gas separation device 10 toward the TSA gas separation device 20.

Next, a specific configuration of the TSA gas separation device 20 will be described. As shown in FIG. 6, the TSA gas separation apparatus 20 includes adsorption towers 21A and 21B (TSA adsorption towers), lines 22a to 22e forming gas flow paths, a heat exchanger 23A, a cooler 23B, and a refrigerant tank 23C. A refrigerant pump 23D, a brine cooler 23E, a heat medium tank 23F, a heat medium pump 23G, and lines 24a to 24h related to the refrigerant flow and the heat medium flow, and a semi-purified gas from the PSA gas separation device 10 From G ₂ , the argon can be further concentrated and separated by using a temperature fluctuation adsorption method (TSA method).

Each of the adsorption towers 21A and 21B has gas passage ports 21a and 21b, at least one adsorption tube 21c, two tube plates 21d, and space portions 21e and 21f. The suction pipe 21c, the adsorbent for selectively adsorbing the impurity serving nitrogen contained in the semi-purified gas G ₂ (TSA adsorbent) is filled. As such an adsorbent, for example, CaX type zeolite, Ca mordenite type zeolite, and LiX type zeolite can be used. One type of adsorbent may be filled in the adsorption tube 21c, or a plurality of types of adsorbents may be stacked and filled in the adsorption tube 21c. Such an adsorption tube 21c is supported by a tube plate 21d in the tower, and the interior of the adsorption tube 21c communicates with the space 21e or the gas passage ports 21a and 21b. The space portion 21e is a part of the gas flow path, the space portion 21f is a portion that receives a refrigerant and a heat medium, and the space portions 21e and 21f are partitioned by a tube plate 21d.

A purified gas take-out line 30 and an off-gas line 40 are connected to the TSA gas separation device 20. The purified gas take-out line 30 is a line for recovering the purified gas G ₆ led out from the gas passage ports 21b of the adsorption towers 21A and 21B described later. The off-gas line 40 is for discharging off-gas (gas G ₇ ) led out from the gas passage ports 21a of the adsorption towers 21A and 21B described later to the outside of the apparatus (in the atmosphere).

Line 22a is, adsorption column 21A quasi purified gas G ₂ from the PSA gas separation apparatus 10 is for supplying the 21B, a semi-purified gas line 15 described above, the adsorption tower 21A via a branch passage, 21B The gas passage ports 21a are connected to each other.

Line 22b is a flow path of the purified gas G ₆ that each of the adsorption columns 21A, is derived from 21B, the purified gas extraction line 30, respectively the adsorption tower 21A, the gas passage holes 21b and 21B through a branch passage Are connected.

  The line 22c is for supplying a part of the purified gas flowing through the line 22b to the adsorption towers 21A and 21B, and the gas passage ports of the adsorption towers 21A and 21B via the line 22b and the branch paths. 21b is connected to each other.

Line 22d, each adsorption tower 21A, which is for discharging the gas G ₇ derived from 21B to the outside of the apparatus, the offgas line 40, the adsorption tower 21A via a branch passage, the gas passage holes 21a of the 21B Are connected to each other.

  The line 22e is for connecting the adsorption towers 21A and 21B to each other, and connects the gas passage 21b of the adsorption tower 21A and the gas passage 21b of the adsorption tower 21B via a branch path.

The heat exchanger 23A is for cooling the semi-purified gas G ₂ derived from the adsorption towers 11A, 11B, and 11C of the PSA gas separation device 10 and supplied via the semi-purified gas line 15. The cooler 23B is for cooling the semi-purified gas G ₂ that has passed through the heat exchanger 23A. The refrigerant tank 23C is for holding the liquid refrigerant M1. As the refrigerant M1, for example, an ethanol aqueous solution, a methanol aqueous solution, a calcium chloride aqueous solution, methylene chloride, or ethylene glycol can be used. The refrigerant pump 23D is for sending the refrigerant M1 in the refrigerant tank 23C to the brine cooler 23E side or the adsorption towers 21A and 21B side. The brine cooler 23E is a refrigerant cooler with a refrigerator for cooling the refrigerant M1 to a predetermined temperature before the refrigerant M1 reaches the adsorption towers 21A and 21B. The heat medium tank 23F is for holding the liquid heat medium M2 and heating the heat medium M2. The heating medium tank 23F is provided with predetermined heating means (not shown). As the heat medium M2, for example, an ethanol aqueous solution, a methanol aqueous solution, a calcium chloride aqueous solution, methylene chloride, or ethylene glycol can be used. In the present embodiment, the refrigerant M1 and the heat medium M2 are the same kind of liquid. The heat medium pump 23G is for sending the heat medium M2 in the heat medium tank 23F to the adsorption towers 21A and 21B side.

  Lines 24a and 24b are lines for supplying refrigerant to the adsorption towers 21A and 21B. The refrigerant tanks 23C, the refrigerant pump 23D, and the brine cooler 23E are connected in series, and the lower ends of the space portions 21f of the adsorption towers 21A and 21B. It is provided so that it can communicate with the side.

  Lines 24c and 24d are lines for collecting the refrigerant from the adsorption towers 21A and 21B, and are provided so as to communicate with the upper end side of the space portion 21f of the adsorption towers 21A and 21B and to communicate with the lower end side of the space portion 21f. It has been. The lines 24c and 24d are connected to the refrigerant tank 23C.

  Lines 24e and 24f are lines for supplying a heat medium to the adsorption towers 21A and 21B. The heat medium tank 23F and the heat medium pump 23G are connected in series, and the lower end side of the space portion 21f of the adsorption towers 21A and 21B. It can be communicated with.

  Lines 24g and 24h are lines for recovering the heat medium from the adsorption towers 21A and 21B, can communicate with the upper end side of the space part 21f of the adsorption towers 21A and 21B, and can communicate with the lower end side of the space part 21f. Is provided. The lines 24g and 24h are connected to the heat medium tank 23F.

The lines 22a to 22e and 24a to 24h are provided with a plurality of automatic valves 25a to 25j and 26a to 26h that can be switched between an open state and a closed state, and each of the automatic valves 25a to 25j and 26a. The flow direction and pressure of the fluid in the adsorption towers 21A and 21B are adjusted by appropriately switching the open / closed state of ˜26h. In each of the adsorption towers 21A and 21B, a cycle including an adsorption process (TSA adsorption process) and a regeneration process is repeated according to the switching state of the automatic valves 25a to 25j and 26a to 26h. In the adsorption step, the semi-purified gas G ₂ is supplied to an adsorption tower in which the inside of the adsorption tube 21c is in a predetermined high pressure / low temperature state, thereby adsorbing impurity nitrogen in the semi-purified gas G ₂ to the adsorbent in the adsorption tube 21c. Then, the purified gas G ₆ enriched with argon rather than the semi-purified gas G ₂ is derived from the adsorption tower. In the regeneration process, a decompression process that lowers the pressure in the adsorption tower after the adsorption process is performed, and a temperature raising operation that raises the temperature in the adsorption tower is performed to desorb impurities from the adsorbent and lead out of the tower A heat desorption process performed under a low pressure and a cooling pressure increasing process for simultaneously performing a cooling operation for lowering the temperature in the adsorption pipe 21c and a pressure increasing operation for increasing the pressure in the adsorption pipe 21c in preparation for the adsorption process are sequentially performed. In the adsorption tower performing the adsorption step, the maximum pressure (adsorption pressure) in the adsorption tube 21c is, for example, 0.4 to 1 MPaG, and the minimum temperature (adsorption temperature) of the adsorbent in the adsorption tube 21c is, for example, -50 to -10 ° C. In the adsorption tower performing the heat desorption step, the minimum pressure (desorption pressure) in the adsorption tube 21c is, for example, about atmospheric pressure, and the maximum temperature (desorption temperature) of the adsorbent in the adsorption tube 21c is, for example, 30 to 50. ℃.

In the embodiment of the present invention, the purified gas G ₆ is separated from the semi-purified gas G ₂ using the TSA gas separation device 20 configured as described above. In each adsorption tower 21A, 21B, each process is performed at the timing (step) as shown in FIG. 7, and such a cycle is repeatedly performed by setting steps 1 to 6 as one cycle. FIG. 7 shows the open / closed states of the automatic valves 25a to 25j and 26a to 26h in each step at the same time. In FIG. 7, the open state of each automatic valve is represented by ◯ and the closed state is represented by ×.

  In step 1, the open / close state of each automatic valve is selected as shown in FIG. 7, the adsorption step is performed in the adsorption tower 21A, and the decompression step (decompression and temperature rise in the tower) is performed in the adsorption tower 21B. Yes.

More specifically, in Step 1, the refrigerant M1 is supplied from the refrigerant tank 23C to the lower end side of the space portion 21f of the adsorption tower 21A via the line 24a. The refrigerant M1 is pumped up from the refrigerant tank 23C by the refrigerant pump 23D and cooled by passing through the brine cooler 23E. The cooling temperature of the refrigerant M1 by the brine cooler 23E is, for example, −50 to −40 ° C. At the same time, the refrigerant M1 is collected in the refrigerant tank 23C from the upper end side of the space portion 21f of the adsorption tower 21A via the line 24c. The refrigerant M1 passes through the cooler 23B before being collected in the refrigerant tank 23C, it is used to cool the semi-purified gas G _2. The difference in the specific heat of the refrigerant M1 and quasi purified gas G ₂ is large, it is possible to cool the at cooler 23B efficiently quasi purified gas G _2. The refrigerant M1 circulates between the space portion 21f of the adsorption tower 21A and the brine cooler 23E, whereby the adsorbent in the adsorption pipe 21c of the adsorption tower 21A is continuously cooled and maintained at a low adsorption temperature. The adsorption temperature is at least −50 ° C. In this embodiment, the adsorption temperature is −35 ° C., for example. At the same time, the semi-purified gas G ₂ is introduced to the gas passage 21a side of the adsorption tower 21A via the line 22a, and the impurity nitrogen in the gas G ₂ is adsorbed to the adsorbent in the adsorption pipe 21c of the adsorption tower 21A. The purified gas G ₆ enriched with argon than the semi-purified gas G ₂ is led out from the gas passage port 21b side of the adsorption tower 21A. The purified gas G ₆ is taken out of the apparatus through the line 22b and the purified gas take-out line 30. This purified gas G ₆ passes through the heat exchanger 23A before being taken out of the apparatus, and is used to cool the semi-purified gas G ₂ . In other words, the purified gas G ₆ is heated by the relatively high temperature semi-purified gas G ₂ when passing through the heat exchanger 23A. The internal pressure of the adsorption pipe 21c of the adsorption tower 21A in the adsorption process is in the range of 0.01 to 1 MPaG.

  At the same time, the heat medium M2 is pumped up by the heat medium pump 23G and supplied from the heat medium tank 23F to the lower end side of the space portion 21f of the adsorption tower 21B through the line 24f. In the heat medium tank 23F, the heat medium M2 is heated to 45 to 50 ° C., for example. At the same time, the heat medium M2 is recovered from the upper end side of the space 21f of the adsorption tower 21B to the heat medium tank 23F via the line 24h. The heat medium M2 circulates between the space portion 21f of the adsorption tower 21B and the heat medium tank 23F, whereby the adsorbent in the adsorption pipe 21c of the adsorption tower 21B is heated to raise the temperature. Further, since the adsorption tower 21B has previously performed the adsorption process, the interior of the adsorption tube 21c is at a pressure higher than the atmospheric pressure at the start of step 1 (see step 6 shown in FIG. 7). And the gas in the adsorption pipe 21c of the adsorption tower 21B is led out from the gas passage 21a side, and sent out to the off gas line 40 through the line 22d. Thereby, the inside of the adsorption pipe 21c of the adsorption tower 21B is depressurized to a predetermined pressure.

  In step 2, as shown in FIG. 7, the open / close state of each automatic valve is selected, the adsorption process is performed in the adsorption tower 21A, and the heat desorption process is performed in the adsorption tower 21B.

More specifically, in step 2, the adsorption tower 21A, subsequently adsorption step is carried out from step 1, the purified gas G ₆ is derived. The purified gas G ₆ is heated by the relatively high temperature semi-purified gas G ₂ when passing through the heat exchanger 23A. A part of the heated purified gas G ₆ is recovered outside the apparatus via the line 22b and the purified gas take-out line 30, and the remainder is supplied as purge gas to the adsorption tower 21B via the line 22c.

At the same time, the heat medium M2 circulates between the space portion 21f of the adsorption tower 21B and the heat medium tank 23F, whereby the adsorbent in the adsorption pipe 21c of the adsorption tower 21B continues to be heated to, for example, 40 ° C. The temperature is raised until The maximum temperature of the adsorbent in the heat desorption process is at most 50 ° C. In the adsorption tower 21B, the depressurization step is completed first, and the inside of the adsorption tube 21c is under high temperature and low pressure, so that impurity nitrogen is desorbed from the adsorbent. At the same time, a part of the purified gas G ₆ derived from the adsorption tower 21A is introduced to the gas passage 21b side of the adsorption tower 21B through the line 22c, and from the gas passage 21a side of the adsorption tower 21B. The gas in the adsorption tube 21c is derived. Thereby, the inside of adsorption pipe 21c can be washed. Further, since the purified gas G ₆ introduced into the adsorption tower 21B is heated by the heat exchanger 23A, it contributes to the temperature rise (heating) of the adsorbent in the adsorption pipe 21c. The gas G ₇ derived from the gas passage 21a side of the adsorption tower 21B is sent out to the off gas line 40 via the line 22d. Further, the internal pressure of the adsorption pipe 21c of the adsorption tower 21B in the heat desorption process is in the range of atmospheric pressure to 0.1 MPaG as long as it is lower than the internal pressure of the adsorption pipe 21c in the adsorption process.

  In step 3, as shown in FIG. 7, the open / close state of each automatic valve is selected, the adsorption process is performed in the adsorption tower 21A, and the cooling pressure increasing process is performed in the adsorption tower 21B.

More specifically, in step 3, the adsorption columns 21A, subsequently adsorption step is carried out from step 2, the purified gas G ₆ is derived. A part of the purified gas G ₆ is recovered outside the apparatus via the line 22b and the purified gas take-out line 30, and the remainder is supplied as purge gas to the adsorption tower 21B via the line 22e.

At the same time, the refrigerant M1 is supplied from the refrigerant tank 23C to the lower end side of the space portion 21f of the adsorption tower 21B through the line 24b. The refrigerant M1 is pumped up from the refrigerant tank 23C by the refrigerant pump 23D and cooled by passing through the brine cooler 23E. At the same time, the refrigerant M1 is recovered from the upper end side of the space 21f of the adsorption tower 21B to the refrigerant tank 23C via the line 24d. The refrigerant M1 circulates between the space portion 21f of the adsorption tower 21B and the brine cooler 23E, whereby the adsorbent in the adsorption pipe 21c of the adsorption tower 21B continues to be cooled to, for example, -35 ° C. (adsorption temperature). The temperature is lowered. At the same time, a part of the purified gas G ₆ led out from the adsorption tower 21A is introduced to the gas passage 21b side of the adsorption tower 21B through the line 22e. Thereby, the pressure inside the adsorption pipe 21c of the adsorption tower 21B can be increased. Further, since the purified gas G ₆ introduced into the adsorption tower 21B is low in temperature and not heated through the adsorption process, it contributes to cooling of the adsorbent in the adsorption pipe 21c of the adsorption tower 21B.

  In steps 4 to 6, the adsorption step is performed in the adsorption tower 21B in the same manner as in the adsorption tower 21A in steps 1 to 3. At the same time, in steps 4 to 6, as in the adsorption tower 21B in steps 1 to 3, in the adsorption tower 21A, the depressurization step (step 4), the heat desorption step (step 5), and the cooling pressure increase step ( Step 6) is performed.

As described above, in the TSA gas separation device 20, the adsorption tower 21A, TSA adsorption step in one of 21B is always effected from the argon purification apparatus X, the purified gas G ₆ of a high purity is continuously recovered. In this purified gas G ₆ , nitrogen has been removed to a concentration of less than 1 mol ppm.

In the argon purification method of the present embodiment, pretreatment, PSA method, and TSA method are executed to increase the purity of argon. As a result, energy for obtaining highly purified argon (purified gas G ₆ ) is obtained. It is easy to achieve a high recovery rate while reducing.

In the pretreatment of this method, the oxygen molar concentration in the raw material gas G ₀ is adjusted as necessary so that all the carbon monoxide and hydrogen in the raw material gas G ₀ can react with oxygen, and then the reactor In step 3, a raw material gas conversion reaction (represented by the above reaction formulas (1) and (2)) is performed using a ruthenium catalyst. The ruthenium catalyst has an ability to react with carbon monoxide and hydrogen over other platinum-based catalysts and the like, and completely converts carbon monoxide and hydrogen contained as impurities in the raw material gas G ₀ into other compounds. be able to. In addition, according to the ruthenium catalyst, the reaction temperature may be lower than that of other catalysts, which contributes to a reduction in energy for heating the raw material gas G _{0 in} the heater 2.

In the PSA method of the present method, for example, the gas in the adsorption tower 11A (11B, 11C) that has finished the adsorption step has a relatively high argon concentration (similar to the semi-purified gas G ₂ ). In the pressure equalization step, a high gas is introduced into the other adsorption towers 11B and 11C that have undergone the desorption and washing step, so that the other adsorption towers 11B and 11C are boosted in preparation for the adsorption step. Therefore, the other adsorption columns 11B, high above the argon concentration is introduced into the 11C gas is taken out as a quasi purified gas G ₂ at the adsorption step after without being discharged out of the apparatus, following TSA gas separation process It is attached to. Therefore, this method is suitable for obtaining high purity argon with a high recovery rate.

Further, in the PSA method of the present method, the pressure equalizing step includes a first pressure equalizing step and a second pressure equalizing step. For example, as can be understood with reference to steps 3 and 4 (FIGS. 3 to 5) described above, in the first pressure equalization process, the concentration of argon is high from the start of the pressure equalization process to the middle in the adsorption tower 11A that has undergone the adsorption process. While deriving the gas G ₃ (first gas), the first gas is introduced into the adsorption tower 11B, and the internal pressure of the adsorption towers 11A and 11B is set to a first pressure lower than the adsorption pressure. In the second pressure equalizing step, the gas G ₄ (second gas) having a high argon concentration is led out in the adsorption tower 11A after the first pressure equalizing (depressurizing) step, and the second gas is removed from the desorption cleaning step. Then, the internal pressure of the adsorption towers 11B and 11C is set to a second pressure lower than the first pressure. The first pressure equalizing step and the second pressure equalizing step are performed between two adsorption towers having a relatively small pressure difference, and the combination of the two adsorption towers in which the first pressure equalizing step is performed, It is different from the combination of two adsorption towers in which the pressure step is performed. Such a first pressure equalization step and a second pressure equalization step can be realized by devising a gas flow generated according to a pressure difference between the adsorption towers in the PSA method performed using three or more adsorption towers. As for the adsorption tower for increasing the pressure in the pressure equalization process, gases G ₄ and G ₃ (second gas and first gas) having a high argon concentration are sequentially introduced from the other two different adsorption towers in two stages and adsorbed. The pressure is increased to a first pressure that is relatively close to the pressure. As a result, more gases G ₄ and G ₃ (second gas and first gas) having a higher argon concentration can be taken out as semi-purified gas G ₂ without being discharged out of the apparatus. Suitable for improving

In the PSA method of this method, a carbon molecular sieve is used as an adsorbent (PSA adsorbent) filled in the adsorption towers 11A, 11B, and 11C. Since the carbon molecular sieve is excellent in oxygen adsorption ability, oxygen in the gas G ₁ (mixed gas) can be almost completely removed by the PSA method, and nitrogen is the only impurity to be removed in the subsequent TSA method. . That is, the adsorption temperature in the TSA method needs to be extremely low when removing oxygen compared to removing nitrogen, and in this method, the only impurity to be removed by the TSA method is nitrogen. The adsorption temperature of the adsorbent (TSA adsorbent) in the adsorption step in the TSA gas separation device 2 can be set to a relatively high temperature (-50 to -10 ° C). Thereby, the cooling energy for removing impurities in the TSA method can be reduced.

  Further, in the TSA method of the present method, the TSA cycle time in the TSA gas separation device 20 can be easily shortened. This is because, in the present embodiment, the temperature variation of the adsorbent is realized by using the liquid refrigerant M1 and the liquid heat medium M2 when executing the TSA method accompanied by the temperature variation of the adsorbent.

  Specifically, in the heat desorption process in the TSA method, the adsorbent in the adsorption pipe 21c is heated using the liquid heat medium M2. The adsorbent is heated by bringing the liquid heat medium M2 into contact with the adsorption tube 21c filled with the adsorbent and supplying heat from the heat medium M2 to the adsorbent in the adsorption tube 21c. Since the specific heat of the liquid heat medium M2 is considerably larger than that of the gas, the liquid heat medium M2 is used as in the present embodiment rather than the case of using the gas as the medium for heating the adsorbent in the TSA method. In the case of heating the adsorbent, the adsorbent can be heated to a desired temperature faster. Thereby, it is possible to complete the heat desorption process in a short time. Shortening the heat desorption process time contributes to shortening the TSA cycle time.

  On the other hand, in the cooling pressurization step, the adsorbent in the adsorption pipe 21c is cooled using the liquid refrigerant M1. The liquid refrigerant M1 is brought into contact with the adsorption pipe 21c filled with the adsorbent, and the adsorbent is cooled by removing heat from the adsorbent in the adsorption pipe 20c by the refrigerant M1. Since the liquid refrigerant M1 has a considerably larger specific heat than the gas, the adsorbent is obtained by using the liquid refrigerant M1 as in this embodiment, rather than using gas as a medium for cooling the adsorbent in the TSA method. In the case of cooling the adsorbent, the temperature of the adsorbent can be lowered to a desired temperature more quickly. Thereby, it is possible to complete the cooling and boosting step in a short time. The shortening of the cooling pressurization process time contributes to the shortening of the TSA cycle time.

  In the argon purification method of this embodiment, the adsorption temperature of the adsorbent in the adsorption step in the TSA gas separation device 20 is −50 ° C. or higher as described above. Such a configuration is preferable from the viewpoint of simply carrying out the method and suppressing the cost required for the apparatus for carrying out the method. This is because cooling the refrigerant M1 to such an extent that at least an adsorption temperature of −50 ° C. is achieved can be realized by a relatively easily available cooling machine or the like.

  Next, another example of the argon purification method according to the present invention will be described. The argon purification method of the present embodiment is the same as the method described above with reference to FIGS. 3 to 5 in the above embodiment with respect to the steps (steps 1 to 9) executed in the respective adsorption towers 11A, 11B, and 11C in the PSA method. Some changes have been made.

  FIG. 8 shows another example of steps performed in each adsorption tower to separate the semi-purified gas enriched with argon from the mixed gas using the PSA gas separation apparatus 10 described above with reference to FIG. .

  In the PSA method of this embodiment, the automatic valves 12a to 12c, 13a to 13c, 14a to 14c, 15a to 15c, 16a to 16c, and 17a to 17c are switched in the manner shown in FIG. For example, one cycle consisting of the following steps 1 to 9 can be repeated. In FIG. 8, the open state of each automatic valve is represented by ◯ and the closed state is represented by ×. In one cycle of the present embodiment, in each of the adsorption towers 11A, 11B, and 11C, an adsorption process, a first pressure equalization (decompression) process, a second pressure equalization (decompression) process, a desorption cleaning process, a recovery process, Two pressure equalization (pressure increase) steps, standby, and a first pressure equalization (pressure increase) step are performed. That is, instead of the desorption cleaning process (the adsorption tower 11C in step 3, the adsorption tower 11A in step 6, and the adsorption tower 11B in step 9) performed in parallel with the first pressure equalization process in the above embodiment, the recovery is performed. Execute the process. FIG. 9 schematically shows the gas flow state in the PSA gas separation apparatus 10 in steps 1 to 9 shown in FIG. FIG. 10 shows a change in the internal pressure of each of the adsorption towers 11A, 11B, and 11C in steps 1 to 9 shown in FIG.

In the recovery process, for example, as can be seen by paying attention to the adsorption tower 11C in step 3, the automatic provided in the branch paths 12C, 13C, 14C, 15C, 16C, and 17C leading to the gas passage ports 11a and 11b of the adsorption tower 11C, respectively. Since all of the valves 12c, 13c, 14c, 15c, 16c, and 17c are closed, the gas entry and exit is blocked. Further, as can be understood with reference to FIGS. 9 and 10, the desorption cleaning process is performed in the previous step 2, and the internal pressure of the adsorption tower 11C is low at the start of the recovery process, but the recovery process (step 3). Then, as shown in FIG. 10, the internal pressure of the adsorption tower 11C slightly increases. The increase in internal pressure during the recovery process is thought to be due to the desorption of argon adsorbed on the adsorbent. Argon has a smaller adsorption capacity than the impurity gas component, and the amount adsorbed by the adsorbent (adsorption capacity) itself is small. On the other hand, due to the adsorption capacity of various gas components in various internal pressure states, argon is not easily desorbed compared to other gas components such as oxygen and carbon dioxide, and the internal pressure is sufficiently low. Sometimes it is easier to desorb. The gas (mainly argon) desorbed during the recovery process is taken out as semi-purified gas G ₂ in the adsorption process performed later. Therefore, the present embodiment in which the recovery step is performed in the PSA method is suitable for further increasing the argon recovery rate.

As mentioned above, although embodiment of this invention was described, the range of this invention is not limited to above-described embodiment. The specific configuration of the argon purification method and apparatus according to the present invention can be variously modified without departing from the spirit of the invention. For example, a configuration different from that of the above embodiment may be adopted for the configuration of the lines forming the gas flow paths of the PSA gas separation device 10 and the TSA gas separation device 20. The gas discharged from the PSA gas separator or TSA gas separator in the above embodiment (gas G ₅ or gas G ₇ in the above embodiment) is not discharged outside the device, for example, a recovery line is provided. Then, the gas may be merged with the raw material gas before being introduced into the concentration adjusting device. According to this configuration, the argon recovery rate in the purified gas can be increased. The number of adsorption towers of the PSA gas separation device is not limited to the three-column type shown in the above embodiment, and the same effect can be expected even when there are four or more towers. Further, a cycle composed of a plurality of steps executed in each of the PSA gas separation device and the TSA gas separation device can also be set to a different aspect from the above embodiment.

[Example 1]
In this example, the source gas G ₀ (argon gas) was purified using the argon purification apparatus X described above with reference to the drawings.

The source gas G ₀ supplied to the argon purifier X through the source gas introduction end E1 is 500 mol ppm of oxygen, 20 mol ppm of hydrogen, 1800 mol ppm of carbon monoxide, 1000 mol ppm of nitrogen, carbon dioxide as impurities. Containing 20 mol ppm of water and 20 mol ppm of water were used. This raw material gas G ₀ was introduced into the reactor 3 at a flow rate of 8.0 L / min in the standard state, and oxygen was added to the raw material gas G ₀ at a flow rate of 7.28 mL / min in the standard state.

The reactor 3 is filled with 96 mL of an alumina-supported ruthenium catalyst (trade name: RUA, manufactured by Zude Chemie Catalysts), and the reaction conditions in the reactor 3 are as follows: temperature is 180 ° C., pressure is atmospheric pressure, space The speed was 4500 / h. In the gas G ₁ (mixed gas) flowing out from the reactor 3, moisture was removed by the dehydrator 6, and impurities were removed by the adsorption device 8 (PSA gas separation device 10 and TSA gas separation device 20). The composition of the impurities in the gas G ₁ introduced into the PSA gas separation apparatus 10 is 450 mol ppm for oxygen, 1000 mol ppm for nitrogen, less than 1 mol ppm for hydrogen, less than 1 mol ppm for carbon monoxide, and 2000 for carbon dioxide. The mol ppm and the water content were less than 1 mol ppm. The impurity composition of the gas G ₁ is shown in the table of FIG.

  The PSA gas separation apparatus 10 is a three-column type equipped with adsorption towers 11A, 11B, and 11C, and each adsorption tower 11A, 11B, and 11C has a carbon molecular sieve (model number: GN-) of columnar formed coal as a PSA adsorbent. 1 L of UC-H, manufactured by Kuraray Chemical Co., Ltd. was filled. The operating conditions of the PSA method were as follows: the adsorption pressure was 0.8 MPaG, the desorption pressure was 10 kPaG, the cycle time was 80 sec / column, and the cycle consisting of the steps shown in FIGS. 8 and 9 was repeated. That is, in the present embodiment, the first pressure equalization process and the second pressure equalization process are performed in two stages with respect to the pressure equalization process, the second pressure equalization process is performed for 5 seconds, and performed in parallel with the first pressure equalization process. For 15 seconds.

The composition of the semi-purified gas G ₂ flowing out from the PSA gas separation apparatus 10 is 99.9 mol% or more of argon, less than 1 mol ppm of oxygen, 220 mol ppm of nitrogen, less than 1 mol ppm of carbon monoxide, carbon dioxide Was 0 mol ppm, and the water content was less than 1 mol ppm. Further, the argon recovery rate in the semi-purified gas G ₂ (ratio of 100% concentration-converted argon in the obtained semi-purified gas G _{2 to} 100% concentration-converted argon in the gas G ₁ introduced into the PSA gas separation device 10) is 55%. The concentration of each gas component is measured using a trace oxygen concentration meter (model number: DF-150E, manufactured by Delta F) for the oxygen concentration, and the gas analyzer (model number: GC) for the carbon monoxide concentration. -FID, manufactured by Shimadzu Corporation) through a metanizer, carbon dioxide concentration is measured using a gas analyzer (model number: GC-TCD, manufactured by Shimadzu Corporation), and nitrogen concentration is measured The gas analyzer (model number: GC-PID, manufactured by GL Science Co., Ltd.) was used, and the moisture was measured using a dew point meter.

The TSA gas separation apparatus 20 is a two-column type equipped with adsorption towers 21A and 21B. Each adsorption tower 21A and 21B is made of CaX zeolite (model number: SA-600A, manufactured by Tosoh Corporation) as a TSA adsorbent. Filled with 1.5 L. The operating conditions of the TSA method were an adsorption pressure of 0.8 MPaG, an adsorption temperature of −35 ° C., a desorption pressure of 0.1 MPaG, and a desorption temperature of 40 ° C. The nitrogen concentration in the purified gas G ₆ flowing out from the TSA gas separation device 20 was less than 1 mol ppm. The results of Example 1 are shown in the table of FIG.

[Example 2]
In this example, the supply mode of the raw material gas G ₀ is different from that of Example 1, and accordingly, the amount of adsorbent used in the PSA method, the operating conditions of the PSA method, and the adsorbent used in the TSA method The filling amount was different from that in Example 1.

In this embodiment, the raw material gas G ₀ supplied to the argon purifier X through the raw material gas introduction end E1 is 6 mol% oxygen, 20 mol ppm hydrogen, 1800 mol ppm carbon monoxide, and 24 mol nitrogen. %, 20 mol ppm of carbon dioxide, and 20 mol ppm of water were used. This raw material gas G ₀ was introduced into the reactor 3 at a flow rate of 8.0 L / min in the standard state. The raw material gas G ₀ is a mixture of air in the process of being sent out toward the argon purifier X, and the oxygen concentration and the nitrogen concentration are considerably higher than those in the first embodiment. For this reason, when the source gas G ₀ is introduced into the argon purifier X through the source gas introduction end E1, the oxygen concentration is sufficient to transform all of carbon monoxide and hydrogen into carbon dioxide and water. Addition of oxygen was unnecessary.

The same PSA adsorbent as that used in Example 1 was used for each of the adsorption towers 11A, 11B, and 11C of the PSA gas separation apparatus 10, but the filling amount was 4L. The operating conditions of the PSA method are as follows: the adsorption pressure is 0.8 MPaG, the desorption pressure is 10 kPaG, the cycle time is 120 sec / column, and the pressure equalization process is 5 sec in the second pressure equalization process, in parallel with the first pressure equalization process. The recovery process performed was performed for 30 seconds. The same TSA adsorbent as that used in Example 1 was used for the adsorption towers 21A and 21B of the TSA gas separation apparatus 20, but the filling amount was 15L. Other conditions were the same as in Example 1. The composition of the semi-purified gas G ₂ and the argon recovery rate are shown in the table of FIG. The nitrogen concentration in the purified gas G ₆ was less than 1 mol ppm.

Example 3
In this example, the raw material gas was purified in the same manner as in Example 1 except that the recovery step was not performed by the PSA method. That is, in this example, the cycle consisting of the steps shown in FIGS. 3 and 4 was repeated. The table of FIG. 11 shows the argon recovery rate when the gas separation operation was performed under the operating conditions in which the composition of the semi-purified gas G ₂ was an oxygen concentration of less than 1 mol ppm or a nitrogen concentration of 220 mol ppm. The nitrogen concentration in the purified gas G ₆ was less than 1 mol ppm.

Example 4
In this example, the raw material gas was purified in the same manner as in Example 1 except that the pressure equalization step was changed to one step instead of two steps by the PSA method. In this embodiment in which the pressure equalization process is one stage, steps 3, 6, and 9 are omitted from the steps shown in FIGS. 8 and 9, and the desorption cleaning process in steps 2, 5, and 8 is the recovery process. The cycle consisting of the steps replaced with was repeated. The table of FIG. 11 shows the argon recovery rate when the gas separation operation was performed under the operating conditions in which the composition of the semi-purified gas G ₂ was an oxygen concentration of less than 1 mol ppm or a nitrogen concentration of 220 mol ppm. The nitrogen concentration in the purified gas G ₆ was less than 1 mol ppm.

Example 5
In this example, the source gas was purified in the same manner as in Example 1 except that the pressure equalization process was changed to one stage instead of two stages by the PSA method, and the recovery process was not performed. In this example, a cycle consisting of steps in which steps 3, 6, and 9 were omitted from the steps shown in FIGS. 3 and 4 was repeated. The table of FIG. 11 shows the argon recovery rate when the gas separation operation was performed under the operating conditions in which the composition of the semi-purified gas G ₂ was an oxygen concentration of less than 1 mol ppm or a nitrogen concentration of 220 mol ppm. The nitrogen concentration in the purified gas G ₆ was less than 1 mol ppm.

[Comparative Example 1]
In this comparative example, the catalyst charged in the reactor 3 was different from that in Example 1 above. In this comparative example, the reactor 3 is filled with 96 mL of an alumina-supported platinum catalyst (trade name: DASH-220 catalyst, manufactured by N.E. Chemcat Co., Ltd.). Was 180 ° C., the pressure was atmospheric pressure, and the space velocity was 4500 / h. The other conditions were the same as in Example 1, and the raw material gas was purified. The composition of impurities in the gas G ₁ (the gas that has passed through the reactor 3 and the dehydrator 6) introduced into the PSA gas separation apparatus 10 is 950 mol ppm for oxygen, 1000 mol ppm for nitrogen, less than 2 mol ppm for hydrogen, Carbon oxide was 1410 mol ppm, carbon dioxide was 560 mol ppm, and water was less than 1 mol ppm. The impurity composition of the gas G ₁ is shown in the table of FIG. In this comparative example, the carbon monoxide concentration (200 mol ppm) in the semi-purified gas G _{2 that} was subjected to the PSA method was also high. In the gas separation by the TSA method, carbon monoxide in the semi-purified gas G ₂ is preferentially adsorbed over nitrogen, and the adsorbed carbon monoxide is difficult to desorb. Therefore, the amount of nitrogen adsorbed and removed is substantially reduced, and the purified gas G ₆ finally obtained through the TSA method has nitrogen remaining at 5 mol ppm and carbon monoxide at 1 mol ppm. Purity of argon could not be obtained.

[Comparative Example 2]
In this comparative example, the raw material gas was purified in the same manner as in Comparative Example 1 except that the temperature in the reactor 3 was changed to 300 ° C. The composition of the impurities of the gas G ₁ introduced into the PSA gas separation apparatus 10 is shown in the table of FIG. The gas compositions of the semi-purified gas G ₂ and the purified gas G ₆ in this comparative example were the same as those in Example 1. In this comparative example, since the temperature in the reactor 3 needs to be as high as 300 ° C., the energy required for heating the raw material gas in the heater 2 was considerably larger than in the example.

[Comparative Example 3]
In this comparative example, the source gas was purified in the same manner as in Example 1 except that the pressure equalization step was not performed by the PSA method and the recovery step was not performed. The table of FIG. 11 shows the argon recovery rate when the gas separation operation was performed under the operating conditions in which the composition of the semi-purified gas G ₂ was an oxygen concentration of less than 1 mol ppm or a nitrogen concentration of 220 mol ppm. The nitrogen concentration in the purified gas G ₆ was less than 1 mol ppm.

  According to Examples 1 to 5 of the present invention, high-purity argon (purified gas) from which impurities are almost completely removed can be obtained. This is because the carbon monoxide and hydrogen, which are impurities, are almost completely changed to carbon dioxide and water (some may be changed to methane) by carrying out pretreatment using a ruthenium catalyst. It is thought that carbon monoxide and hydrogen were substantially removed. In addition, as can be understood by comparing Examples 1 to 5 and Comparative Example 3 in the table shown in FIG. 11, when the pressure equalizing step is performed in the PSA method, compared with the case where the pressure equalizing step is not performed. The argon recovery rate was high. In the pressure equalization process, the argon recovery rate in the second stage was higher than that in the first stage, and the argon recovery rate was higher when the recovery process was performed by the PSA method than when the recovery process was not performed. Furthermore, as shown in Comparative Example 1 in the table of FIG. 12, when a platinum catalyst is used instead of the ruthenium catalyst in the pretreatment (the temperature in the reactor 3 is 180 ° C.), the purity of argon in the obtained gas is It was not very expensive. This is because carbon monoxide and hydrogen did not sufficiently react with oxygen in the pretreatment, and carbon monoxide and hydrogen (especially carbon monoxide) remained at a relatively high concentration in the pretreated gas. It is thought that.

X Argon purification device 1 Concentration control device 2 Heater 3 Reactor 4 Cooler 5 Compressor 6 Dehydrator 7 Line 8 Adsorber 10 PSA gas separation device 11A, 11B, 11C Adsorption tower (PSA adsorption tower)
12 Line 13 Off-gas line 14 Lower pressure equalization line 15 Semi-purified gas line 16 Washing line 17 Upper pressure equalization line 20 TSA gas separation devices 21A and 21B Adsorption tower (TSA adsorption tower)
21a Gas passage (first gas passage)
21b Gas passage (second gas passage)
21c Adsorption pipes 22a to 22e Line 23C Refrigerant tank 23F Heat medium tank 24a to 24h Line 30 Purified gas take-out line 40 Off-gas line M1 Refrigerant M2 Heat medium

Claims (9)

A method for concentrating and purifying argon from an argon gas containing at least oxygen, carbon monoxide, hydrogen and nitrogen as impurities,
The argon gas is brought into contact with the ruthenium catalyst, and the carbon monoxide and hydrogen contained in the argon gas are reacted with oxygen, whereby the carbon monoxide and hydrogen are substantially removed by changing to carbon dioxide and water. Processing steps;
In the state where the PSA adsorption tower is at a relatively high pressure by the pressure fluctuation adsorption method using three or more PSA adsorption towers packed with the PSA adsorbent, the pretreatment step is performed on the PSA adsorption tower. PSA adsorption for introducing a semi-purified gas enriched in argon from the PSA adsorption tower by introducing a mixed gas from which carbon monoxide and hydrogen have been removed and adsorbing impurities in the mixed gas to the PSA adsorbent Step, depressurizing the PSA adsorption tower to desorb impurities from the PSA adsorbent, and desorbing the gas from the PSA adsorption tower; introducing a cleaning gas into the PSA adsorption tower while removing gas from the PSA adsorption tower And a pressure equalization step for equalizing the internal pressure of the PSA adsorption tower that has undergone the adsorption step and the internal pressure of the PSA adsorption tower that has undergone the washing step. A pressure swing gas separation step for repeating the Le,
The semi-purified gas is introduced into the TSA adsorption tower at a low temperature by the TSA adsorbent in the TSA adsorption tower by a temperature fluctuation adsorption method performed using a TSA adsorption tower filled with the TSA adsorbent. A TSA adsorption step for adsorbing impurities in the semi-purified gas to the TSA adsorbent and deriving a purified gas enriched in argon from the semi-purified gas from the TSA adsorption tower; and in the TSA adsorption tower A regeneration step of regenerating the TSA adsorbent by desorbing impurities from the TSA adsorbent and deriving off-gas from the TSA adsorption tower while raising the TSA adsorbent to a high temperature. An argon purification method comprising: a temperature fluctuation adsorption gas separation step that is repeatedly performed.   The mixed gas before the pre-treatment is adjusted such that the oxygen molar concentration in the mixed gas exceeds 1/2 of the sum of the molar concentration of carbon monoxide and the molar concentration of hydrogen. The argon purification method as described. The pressure equalization step in the pressure-variable gas separation step is a process in which the first gas is led out from the PSA adsorption tower that has undergone the adsorption step from the start to the middle of the pressure equalization step, and the internal pressure of the PSA adsorption tower is determined as the adsorption pressure. A first pressure equalizing step for lowering the first pressure, and a second gas derived from the PSA adsorption tower to set the internal pressure of the PSA adsorption tower to a second pressure lower than the first pressure. A second pressure equalization step after the pressure equalization step,
In the second pressure equalization step, the second gas is introduced into the PSA adsorption tower that has undergone the cleaning step, and the internal pressure of the PSA adsorption tower is increased to the second pressure.
In the first pressure equalizing step, the first gas is introduced into the PSA adsorption tower whose internal pressure has been increased to the second pressure through the second pressure equalizing step, and the internal pressure of the PSA adsorption tower is set to the first pressure. The argon purification method according to claim 1 or 2, wherein the pressure is increased to a pressure.   After the washing step and before the second pressure equalization step, the gas flow into and out of the PSA adsorption column in a relatively low pressure state is blocked through the washing step, thereby allowing the inside of the PSA adsorption column The argon purification method according to claim 3, further comprising a recovery step for recovering the gas by desorbing the gas from the PSA adsorbent.   The argon purification method according to any one of claims 1 to 4, wherein the PSA adsorbent includes carbon molecular sieve. The TSA adsorption tower includes an adsorption tube filled with the TSA adsorbent therein,
In the TSA adsorption process, the TSA adsorbent is cooled by passing a liquid refrigerant through the TSA adsorption tower,
The argon purification method according to any one of claims 1 to 5, wherein in the regeneration step, the TSA adsorbent is heated by passing a liquid heat medium through the TSA adsorption tower.   The argon purification method according to any one of claims 1 to 6, wherein the adsorption temperature in the TSA adsorption step is -50 to -10 ° C. An apparatus for concentrating and purifying argon from an argon gas containing at least oxygen, carbon monoxide, hydrogen and nitrogen as impurities,
A pretreatment device for bringing the argon gas into contact with a ruthenium catalyst to react carbon monoxide and hydrogen contained in the argon gas with oxygen;
In the state where the PSA adsorption tower is at a relatively high pressure by the pressure fluctuation adsorption method using three or more PSA adsorption towers packed with the PSA adsorbent, the pretreatment step is performed on the PSA adsorption tower. PSA adsorption for introducing a semi-purified gas enriched in argon from the PSA adsorption tower by introducing a mixed gas from which carbon monoxide and hydrogen have been removed and adsorbing impurities in the mixed gas to the PSA adsorbent Step, depressurizing the PSA adsorption tower to desorb impurities from the PSA adsorbent, and desorbing the gas from the PSA adsorption tower; introducing a cleaning gas into the PSA adsorption tower while removing gas from the PSA adsorption tower And a pressure equalization step for equalizing the internal pressure of the PSA adsorption tower that has undergone the adsorption step and the internal pressure of the PSA adsorption tower that has undergone the washing step. A pressure swing adsorption gas separation apparatus configured to perform repeated Le,
In the state where the TSA adsorbent in the TSA adsorption tower is at a low adsorption temperature by the temperature fluctuation adsorption method performed using the TSA adsorption tower packed with the TSA adsorbent, the semi-purified gas is added to the TSA adsorption tower. And the TSA adsorption step for adsorbing impurities in the semi-purified gas to the TSA adsorbent and deriving a purified gas enriched in argon from the semi-purified gas from the TSA adsorption tower, and the TSA A regeneration step for regenerating the TSA adsorbent by desorbing impurities from the TSA adsorbent while deriving off-gas from the TSA adsorber while raising the TSA adsorbent in the adsorption tower to a high temperature. An argon purification device comprising: a temperature fluctuation adsorption gas separation device configured to repeatedly perform a cycle including the same. The TSA adsorption tower includes a first gas passage port and a second gas passage port, and includes an adsorption pipe that is in communication with the first and second gas passage ports and filled with the TSA adsorbent,
The temperature fluctuation adsorption gas separator is
A refrigerant storage tank for holding liquid refrigerant supplied to the TSA adsorption tower to cool the TSA adsorbent in the adsorption pipe;
A heating medium storage tank for holding a liquid heating medium supplied to the TSA adsorption tower in order to heat the TSA adsorbent in the adsorption pipe;
A first refrigerant line for supplying the refrigerant from the refrigerant storage tank to the TSA adsorption tower;
A second refrigerant line for returning the refrigerant from the TSA adsorption tower to the refrigerant storage tank;
A first heat medium line for supplying the heat medium from the heat medium storage tank to the TSA adsorption tower;
The argon purification apparatus according to claim 8, further comprising: a second heat medium line for returning the heat medium from the TSA adsorption tower to the heat medium storage tank.

Images