JP2021088484A - Methane removal device, high purity nitrogen supply system, gas chromatograph analysis system, and catalyst function regeneration method - Google Patents

Abstract

To provide a technology capable of continuously performing appropriate methane removal when high purity nitrogen gas is produced.SOLUTION: A residual methane removing device 12 comprises: a catalyst 121 using a metal oxide as a carrier for ventilating nitrogen gas from which oxygen is separated and burning and removing a methane gas remaining in the nitrogen gas; and a catalyst function recovery device 20 for regenerating the function of the catalyst 121 by ventilating the catalyst 121 with oxygen.SELECTED DRAWING: Figure 2

Description

The present invention relates to a methane removal device, a high-purity nitrogen supply system, a gas chromatograph analysis system, and a catalyst function regeneration method.

As a method for producing high-purity nitrogen, purification of nitrogen gas in which oxygen is membrane-separated from compressed air by the PSA method is common. Nitrogen gas purified by PSA (referred to as "raw gas") cannot remove methane, which is a lighter component than nitrogen, due to the characteristics of membrane separation. Similarly, helium, hydrogen, etc. remain, but helium is always inactive in the gas chromatography detector and does not pose a problem. On the other hand, methane has an extremely low boiling point and cannot be captured even at the temperature of liquid nitrogen. Moreover, since it has no polarity, it cannot be removed by adsorption. Therefore, at present, it is most rational to convert _{methane into CO 2} by combustion in order to remove methane constantly.

For example, Patent Document 1 (Patent No. 5852422) discloses a technique for burning methane in an organic combustion catalyst tube in an ultra-high purity nitrogen purification method using compressed air. The specific principle is as follows. That is, since the raw gas is nitrogen gas from which oxygen has been removed to the utmost limit, the inside of the organic matter combustion catalyst tube is originally in an oxygen-deficient state, and methane cannot be completely burned. By allowing a platinum catalyst using alumina (aluminum oxide Al ₂ O ₃ ) as a carrier to exist in the combustion tube, the oxygen content of alumina reacts with methane, and the combustion reaction according to the following formula (1) proceeds.
3CH ₄ + 4Al ₂ O ₃ → 3CO ₂ + 6H ₂ O + 8AL ・ ・ ・ Equation (1)
In the above reaction, 3 mol of methane is oxidized by 4 mol of alumina (aluminum oxide) to carbon dioxide (CO ₂ ) and water (H ₂ O), and reduced aluminum is produced.
Further, Patent Document 2 (Patent No. 3325805) discloses a technique of converting impurity hydrocarbons into carbon dioxide and water using a catalyst and then cooling and removing them.

Patent No. 5852422 Patent No. 3325805

In the technique disclosed in Patent Document 1, when the reaction process of combustion is continued, alumina is finally consumed and the catalytic function is lost. As a matter of course, in a state where the catalytic function is lost or combustion is insufficient, nitrogen gas in which methane has not been completely removed will be discharged. That is, there is a problem that the analysis by the gas chromatograph, which is the discharge destination of the nitrogen gas, becomes inaccurate, and a technique capable of continuously purifying the ultra-high purity nitrogen gas from which methane has been removed has been required.

An object of the present invention is to provide a technique capable of continuously performing appropriate methane removal when producing high-purity nitrogen gas.

The methane removing apparatus of the present invention comprises a catalyst using a metal oxide as a carrier, which ventilates a nitrogen gas from which oxygen has been separated and burns and removes the methane gas remaining in the nitrogen gas.
A catalyst function recovery means for regenerating the function of the catalyst by aerating oxygen through the catalyst, and
To be equipped.

The high-purity nitrogen supply system of the present invention includes the above-mentioned methane removal device and
A nitrogen generator that supplies the nitrogen gas to the methane removal device,
A residual component removing device that obtains nitrogen gas from which the methane gas has been removed by the methane removing device and removes at least water and carbon dioxide from the nitrogen gas.
To be equipped.

The gas chromatograph analysis system of the present invention includes the above-mentioned high-purity nitrogen supply system and
A gas chromatograph that receives nitrogen gas from the high-purity nitrogen supply system,
A gas chromatograph analysis system.

The catalytic function regeneration method of the present invention includes a nitrogen purification apparatus that separates oxygen from air to purify nitrogen gas.
The above is executed in a high-purity nitrogen supply system including a residual methane removal device provided with a catalyst using a metal oxide as a carrier for burning and removing methane remaining in the nitrogen gas purified by the nitrogen purification device. It is a method for regenerating the catalytic function of a catalyst.
When the nitrogen gas is not aerated through the catalyst, a gas containing oxygen is aerated through the catalyst to regenerate the catalytic function of the catalyst.

According to the present invention, it is possible to realize a technique capable of continuously performing appropriate methane removal when producing high-purity nitrogen gas.

It is a block diagram which shows the schematic structure of the gas chromatograph analysis system of embodiment. It is a block diagram which shows the schematic structure of the high-purity nitrogen supply system of an embodiment. It is a flowchart of the catalyst function recovery process by the high-purity nitrogen supply system of embodiment. It is a flowchart of the catalyst function regeneration processing of the catalyst of the residual methane removal apparatus of embodiment. It is a figure which shows the diagram of the gas chromatograph (three-component simultaneous analyzer) of an embodiment.

<Outline of Embodiment>
The outline of the embodiment is as follows.
In the present embodiment, the nitrogen gas from which oxygen in the compressed air is separated is purified to high purity by a high-purity nitrogen supply system and supplied to a gas chromatograph. At this time, the residual methane in the nitrogen gas is burnt and removed by a catalyst having a metal oxide. As a result, stable use as a methane-free nitrogen carrier gas in gas chromatographs is realized.
Examples of the metal oxide include aluminum oxide (alumina), copper oxide, and titanium oxide. In consideration of the balance between cost, market availability, and catalytic ability, the following catalysts use aluminum oxide as the metal oxide. That is, an example of a platinum catalyst of an alumina carrier will be described.
By controlling the flow path switching valve, the platinum catalyst of the alumina carrier consumed for methane combustion under the condition of oxygen deficiency due to oxygen separation is compressed at the time of disconnection from the carrier gas flow for gas chromatograph. A gas containing at least oxygen, such as dry air, is ventilated through the deteriorated catalyst. This restores the methane combustion function of the catalyst.
Hereinafter, a specific description will be given.

<Gas chromatograph analysis system 100>
FIG. 1 is a block diagram showing a schematic configuration of a gas chromatograph analysis system 100 according to the present embodiment. The gas chromatograph analysis system 100 includes a high-purity nitrogen supply system 1 and a gas chromatograph 2. The high-purity nitrogen supply system 1 purifies the nitrogen gas from which oxygen in the compressed air has been separated to a high degree of purity and supplies it to the gas chromatograph 2. At this time, the residual methane in the nitrogen gas is burned and removed. The gas chromatograph 2 obtains a methane-free high-purity nitrogen gas (nitrogen carrier gas). When the gas chromatograph 2 is a three-component simultaneous analyzer described later in FIG. 5, it is preferable to supply methane-free high-purity nitrogen gas by the high-purity nitrogen supply system 1 of the present embodiment.

<Outline of high-purity nitrogen supply system 1>
The high-purity nitrogen supply system 1 includes a nitrogen supply device 10, a catalytic function recovery device 20, and a control device 30 (control means). The control device 30 controls the operation of the nitrogen supply device 10 and the catalyst function recovery device 20.

The nitrogen supply device 10 separates and removes oxygen from the air in the atmosphere, removes impurities by catalytic combustion and filtering, purifies high-purity nitrogen gas, and supplies it to the gas chromatograph 2.

The catalyst function recovery device 20 recovers the ability of the catalyst combustion function (hereinafter referred to as “catalyst function”) in the residual methane removal device 12 (described later in FIG. 2) provided in the nitrogen supply device 10. Specifically, the catalyst function recovery device 20 has a function of supplying compressed air to the residual methane removal device 12. The supply of the compressed air to the residual methane removing device 12 is performed at a predetermined timing and for a predetermined time under the control of the control device 30. Details will be described later.

As a result, the catalyst 121 (described later in FIG. 2) of the residual methane removing device 12 is compressed at a time when it is separated from the carrier gas flow for the gas chromatograph 2 by a flow path switching valve (valve) or the like under the control of the control device 30. A gas containing at least oxygen such as dry air is aerated through the deteriorated catalyst 121 to restore the catalytic function of methane by the catalyst 121.
The catalyst function recovery device 20 may be provided as a separate configuration from the residual methane removal device 12, or the residual methane removal device 12 may include the catalyst function recovery device 20.

<Specific configuration of nitrogen supply device 10>
FIG. 2 shows a specific configuration of the nitrogen supply device 10. FIG. 3 shows a flowchart of the high-purity nitrogen purification process in the nitrogen supply device 10. As the nitrogen supply device 10, for example, the technique described in Patent Document 1 (Patent No. 5852422) can be applied. Further, as described in the background art, since there is a request that methane remains and is removed even in the nitrogen gas purified by the PSA method, the nitrogen supply device of the PSA method can also be applied. Hereinafter, a configuration to which the technique of Patent Document 1 is applied will be briefly described.

The nitrogen supply device 10 includes a nitrogen generator 11, a residual methane removing device 12, and a water / carbon dioxide removing device 13 (residual component removing device) from the upstream side to the downstream side.

The nitrogen generator 11 includes, as high-purity nitrogen purification steps, an air compression step (S101), a water removal step (S102), an oil removal step (S103), a dry air purification step (S104), a trace organic matter removal step (S105), and the like. The oxygen removal step (S106) is performed. As a result, nitrogen and oxygen are separated, and high-purity nitrogen gas is discharged to the residual methane removing device 12.
The residual methane removing device 12 burns and removes methane contained in the high-purity nitrogen gas obtained from the nitrogen generator 11 by the methane removing step (S107).
The water / carbon dioxide removing device 13 removes water and carbon dioxide contained in the high-purity nitrogen gas obtained after the methane removing step (S107) in the residual methane removing device 12 by the water / carbon dioxide removing treatment (S108). To do.
Hereinafter, the configurations of the nitrogen generator 11, the residual methane removing device 12, and the water / carbon dioxide removing device 13 and each step (S101 to S108) in them will be specifically described.

(Air compression step: S101)
The nitrogen generator 11 uses a compressor as an air compression step to compress the air in the room to 5 to 8 atmospheres. Any compressor can be used as long as it can compress air to 5 to 8 atm, but an oil-free compressor is preferable in order to avoid mixing of oil mist.

The following treatment is performed on the compressed air, but due to the pressure of the compressed air, the air from one treatment to the next process is automatically sent only by connecting the ventilation pipe. As the compressed air ventilation pipe, a stainless steel pipe or a polytetrafluoroethylene pipe having an outer diameter of 3 mm to 10 mm should be used to prevent impurities from remaining and to cool the gas after the heat treatment with the catalyst 121 or the like. Is preferable, and it is more preferable to use 316 stainless steel.

(Moisture removal step: S102)
The nitrogen generator 11 removes water from the compressed air by a moisture trap. The moisture trap is a moisture trap that can remove dust up to 5 μm, and preferably has a polypropylene element having a filtration degree of 0.50 μm or less, and CKD, trade name; F3000 type is particularly preferable. When the moisture trap is used, it is preferable to use two stages in series.

(Oil removal step: S103)
The nitrogen generator 11 removes the oil content of the compressed air whose water content has been roughly removed by the water removal step (S102) by the oil mistrap. The oil mistrap used in this treatment ^{has a function of removing oil up to 0.01 mg / m 3} or less, and preferably has a fiber filter having a filtration degree of 0.01 μm or less, manufactured by CKD, trade name; M3000. Molds are particularly preferred. The order of the treatment steps may be different between the water removal step (S102) and the oil removal step (S103).

(Dry air purification step: S104)
The nitrogen generator 11 purifies dry air by using a tube with a built-in water separation film for compressed air from which water and oil have been removed by the water removal step (S102) and the oil removal step (S103). The water separation membrane used here can further remove moisture from the compressed air to an outlet air dew point of −30 ° C. or lower, and preferably includes a hollow fiber membrane made of aromatic polyimide having a pore size of 450 to 550 μm. Ube Industries, Ltd., trade name; UMS-B2V is particularly preferable.

(Step of removing trace organic substances: S105)
The nitrogen generator 11 removes the dry air having an outlet air dew point of −30 ° C. or lower purified in the dry air purification step (S104) by adsorbing a trace amount of residual organic matter using a hydrocarbon removal pipe. The hydrocarbon removal pipe used here is a hydrocarbon removal pipe filled with granular activated carbon having a diameter of 2 to 6 mm and adsorbs and removes a trace amount of residual organic matter. Among them, Shimadzu Corporation, trade name; 221-05619-01. Especially preferable.

(Oxygen removal step: S106)
The nitrogen generator 11 removes oxygen from the dry air from which a trace amount of residual organic matter has been adsorbed and removed in the trace organic matter removing step (S105) by using an oxygen-nitrogen separation membrane built-in tube. The oxygen-nitrogen separation membrane-incorporated tube used here includes a polyimide hollow fiber separation membrane having a pore size of 450 to 550 μm, and Ube Industries, Ltd., trade name; UBE NM-B01A is particularly preferable.

(Iterative processing)
The nitrogen generator 11 repeats at least the treatments of the trace organic matter removing step (S105) and the oxygen removing step (S106) for the compressed air after the treatment of the oxygen removing step (S106). Through the above treatment, the nitrogen generator 11 obtains air (raw gas) having a nitrogen purity of 99.999%, and discharges the raw gas to the residual methane removing device 12.

It is preferable to attach an oxygen indicator having an ability to detect 1 ppm of oxygen to the treatment step after the trace organic matter removing step (S105) or the oxygen removing step (S106). Since the filter of the oxygen indicator is not discolored, it can be recognized that the oxygen concentration in the purified nitrogen gas is 1 ppm or less.

By connecting each of the above treatments in series, 99.99999% or more of high-purity purified nitrogen can be obtained. Further, the air after the completion of this process can be directly supplied to the gas chromatograph 2 or the like at 200 to 400 kPa. However, when methane is removed as in the present embodiment, the methane removal step (S107) and the water / carbon dioxide removal treatment (S108) are performed.
Since argon is an element among the main components in the atmosphere, it cannot be removed by a chemical reaction in principle, but it does not affect the detection sensitivity in gas chromatography.

(Methane removal step: S107)
The methane removing step (S107) in the residual methane removing device 12 will be described.
The residual methane removing device 12 carbonizes the air after the oxygen removing step (S106) discharged from the nitrogen generating device 11, that is, the raw gas having a nitrogen purity of 99.999% by using an organic combustion catalyst tube. Hydrogen (more specifically, methane) is incinerated and removed, and discharged to the water / carbon dioxide removing device 13.

The organic matter combustion catalyst tube used here is a combustion tube filled with a platinum catalyst (catalyst 121) subjected to an alumina treatment having a particle size of 1 to 3 mm, and among them, GL Science's product surface; AOE-2300 is particularly preferable. The air from which hydrocarbons have been incinerated by this process contains carbon dioxide and water generated by combustion.
As described above, since the raw gas is nitrogen gas (purity 99.999%) from which oxygen has been removed to the utmost limit, the organic matter combustion catalyst tube is originally in an oxygen-deficient state, and methane cannot be completely burned. The organic combustion catalyst tube is _{provided with a platinum catalyst using alumina (aluminum oxide Al 2} O ₃ ) as a carrier as the catalyst 121, so that the oxygen content of alumina reacts with methane and burns according to the following formula (1). The reaction proceeds.
3CH ₄ + 4Al ₂ O ₃ → 3CO ₂ + 6H ₂ O + 8AL ・ ・ ・ Equation (1)
In the above reaction, 3 mol of methane is oxidized by 4 mol of alumina (aluminum oxide) to carbon dioxide (CO ₂ ) and water (H ₂ O), and reduced aluminum is produced.

(Moisture / carbon dioxide removal treatment S108)
The water / carbon dioxide removing treatment (S108) in the water / carbon dioxide removing device 13 will be described.
The water / carbon dioxide removing device 13 mainly removes water and carbon dioxide generated by combustion of methane with respect to the nitrogen gas removed by completely burning methane in the residual methane removing device 12 (catalyst 121).

(Specific configuration example of the water / carbon dioxide removing device 13)
Specifically, the water / carbon dioxide removing device 13 includes a water removing device 131, a large-capacity activated carbon (A) 132, a gas filter (moisture) 133, a gas filter (oxygen) 134, and dioxide in this order from the upstream side. A carbon removal filter 135 and a large-capacity activated carbon (B) 136 are provided.

(Moisture removing device 131)
The water removing device 131 is, for example, a hygroscopic agent pipe, which acquires the nitrogen gas discharged from the residual methane removing device 12 and adsorbs the organic matter (CO2) and water in the nitrogen gas to obtain the large-capacity activated carbon (A). Discharge to 132. As the water removing device 131, for example, there is a product name manufactured by Shimadzu Corporation; Shimadzu Gas Filter (MS5A).

(Large-capacity activated carbon (A) 132)
The large-capacity activated carbon (A) 132 removes hydrocarbons in the nitrogen gas discharged from the water removing device 131 and discharges the hydrocarbon to the water / oxygen removing device 133 and the water / carbon dioxide removing device (B) 133. For example, as the large-capacity activated carbon (A) 132, there is a large hydrocarbon trap manufactured by GL Sciences.

(Gas filter (moisture) 133)
The gas filter (moisture) 133 removes the moisture in the nitrogen gas discharged from the large-capacity activated carbon (A) 132 and discharges it to the gas filter (oxygen) 134. As the gas filter (moisture) 133, for example, there is a product name manufactured by GL Sciences Co., Ltd .; a super clean gas filter (with a moisture filter and an indicator).

(Gas filter (oxygen) 134)
The gas filter (oxygen) 134 removes oxygen in the nitrogen gas discharged from the gas filter (moisture) 133 and discharges it to the carbon dioxide removing device 135. As the gas filter (oxygen) 134, for example, there is a product name manufactured by GL Sciences Co., Ltd .; a super clean gas filter (with an oxygen filter and an indicator).

(Carbon dioxide remover 135)
The carbon dioxide removing device 135 removes carbon dioxide in the nitrogen gas discharged from the gas filter (oxygen) 134 and discharges it to the large-capacity activated carbon (B) 136. As the carbon dioxide removing device 135, for example, there is a purification tube (OMI-2 or OMI-4) manufactured by SUPELCO, trade name; OMI display function.

(Large-capacity activated carbon (B) 136)
The large-capacity activated carbon (B) 136 relaxes the overreduced state of nitrogen gas and discharges it to the gas chromatograph 2. For example, as a large-capacity activated carbon (B) 136, there is a trade name; large hydrocarbon trap manufactured by GL Sciences. If carbon monoxide (CO) remains in the gas discharged to the gas chromatograph 2, a negative peak derived from carbon monoxide occurs in the FID (flame ionization detector) / GC (gas chromatograph). This is an obstacle to methane analysis as it tends to be the retention time immediately before methane. By installing the large-capacity activated carbon (B) 136 (activated carbon filter) downstream of the carbon dioxide removing device 135 (that is, upstream side of the gas chromatograph 2), the generation of carbon monoxide can be effectively suppressed.

The order of the treatment steps in the water / carbon dioxide removing device 13 may be changed, but it is preferable to perform the treatment in the above order. This is due to the following reasons. That is, when the filter of the carbon dioxide removing device 135 deteriorates, carbon dioxide is mixed with the carrier gas. This raises the background of the thermal conductivity detector (TCD) and makes carbon dioxide detection difficult. This is because in order to prevent deterioration of the filter of the carbon dioxide removing device 135, it is necessary to sufficiently remove water and oxygen in the previous stage.

<Catalyst function recovery device 20>
Next, the function and configuration of the catalyst function recovery device 20 will be described.
As described above, when the reaction process of methane combustion is continued in the residual methane removing device 12, the alumina of the catalyst 121 is finally consumed and the catalyst function is lost. As a matter of course, in a state where the catalytic function is lost or combustion is insufficient, nitrogen gas in which methane has not been completely removed will be discharged. That is, the analysis by the gas chromatograph 2 which is the discharge destination of the nitrogen gas becomes inaccurate.

Therefore, in the present embodiment, under the control of the control device 30, the catalyst function recovery device 20 supplies compressed air to the residual methane removing device 12 for a predetermined time at a predetermined timing, and the catalyst of the residual methane removing device 12 Regenerates 121 alumina.
That is, a reaction opposite to the above formula (1) is caused, and the reoxidation treatment from metallic aluminum to alumina is carried out by the chemical reaction represented by the following formula (2), and this is carried out by automation.
4Al + 3O ₂ → 2Al ₂ O ₃・ ・ ・ Equation (2)

Since this reaction is carried out in the presence of a Pt catalyst at 400 ° C., it is realized by sending dry air (compressed air) to the catalyst 121 of the residual methane removing device 12. There is a general compressor as a device for supplying dry air (compressed air) to the residual methane removing device 12. It may be shared with the compressor used in the nitrogen generator 11.

In general, it is well known that when oxygen comes into contact with aluminum, it becomes alumina. However, the inventor of the present application brings oxygen into contact with an original compound, alumina (that is, aluminum oxide), which is deprived of oxygen and becomes aluminum and loses catalytic activity (for example, indoor air). It was found that by contacting oxygen to the extent that it is compressed and supplied), it is restored to alumina to the extent that the catalytic activity is restored. Usually, the oxygen reaction of a metal often occurs only on the surface of the metal, and such findings are beyond the common sense of technology.

It is assumed that the nitrogen supply device 10 supplies 1 L of nitrogen gas per minute as a carrier gas to the gas chromatograph 2. When a commercially available device (above GL Science AOE-2300) was used as the residual methane removing device 12, the catalyst life was about 60 days (2 months).

Table 1 shows an example of equivalent calculation for deterioration and recovery of aluminum oxide (alumina) in the catalyst 121.

By comparing the equivalents of the reactions of the formulas (1) and (2), it is estimated that the deterioration of alumina for 2 months can be recovered by flowing dry air at a flow rate of 1 L / min for about 1 minute. If alumina continues to be used until the catalyst life, the nitrogen gas that has not completely removed methane due to insufficient methane combustion removal capacity (catalyst function) before the catalyst capacity is completely lost appears in the gas chromatograph 2. It will be discharged. Therefore, it is desirable to ventilate compressed air for recovery in a state where the methane combustion removal capacity is sufficiently provided. For example, by performing the catalytic function regeneration at a timing that does not affect the operation of the gas chromatograph 2 about once every day to several days, it is possible to constantly supply appropriate nitrogen gas to the gas chromatograph 2.

For example, in actual operation, the efficiency is lower than the above estimation, but by aerating 1 L / min of dry air (compressed air) to the catalyst 121 of the residual methane removing device 12 for about 30 seconds to several minutes / day. Oxidation treatment (reverse reaction) is applied to the deterioration (reduction reaction) of alumina as the supporting base material, and continuous maintenance of the catalytic function, that is, long life of the catalytic function can be realized.

FIG. 4 is a flowchart showing a specific processing example of the catalyst function regeneration step (S200) by the catalyst function recovery device 20.
The control device 30 determines whether or not the catalyst regeneration timing is predetermined (S201). The predetermined catalyst regeneration timing is registered in advance by the administrator.
If it is not the regeneration timing (N in S202), the catalyst regeneration timing is periodically determined in S201.

When the regeneration timing is reached (Y in S202), the control device 30 controls the flow path switching valve to disconnect the nitrogen gas flow path from the residual methane removing device 12 (S203), and compresses air from the catalytic function recovery device 20. Is connected to the residual methane removing device 12 (S204). As a result, the catalyst function recovery device 20 supplies compressed air to the residual methane removal device 12 (S205).

When the supply of compressed air is started, the control device 30 determines whether the predetermined supply time (that is, the supply amount) has ended (S206). If it is not finished (N in S206), the supply of compressed air is continued (S205). When the supply time ends (Y in S206), the control device 30 stops the supply of compressed air from the catalytic function recovery device 20 to the residual methane removal device 12 and disconnects the flow path (S207), and the nitrogen generator 11 A flow path of nitrogen gas is connected to the residual methane removing device 12 to supply nitrogen gas (S208).

In the above process, the catalyst regeneration process was executed at a predetermined time, but the purpose is not limited to this. For example, the control device 30 determines whether or not the catalytic function of the catalyst 121 is equal to or greater than the predetermined capacity, and when it is determined that the catalytic function is less than the predetermined capacity, the catalyst function recovery device is used to restore the catalytic function of the catalyst 121. 20 may be controlled. As a specific example, a sensor for detecting methane, water content, and carbon dioxide is provided to detect whether the residual methane removing device 12 (catalyst 121) is functioning properly. Based on the detection result, for example, when it can be estimated that the catalytic capacity of the catalyst 121 will be lower than the predetermined value after a lapse of a predetermined time, a warning is output or the catalyst function recovery device is not operated at the timing when the gas chromatograph 2 is not operated. The function recovery process of the catalyst 121 by 20 is executed. Further, based on the cumulative values of the supply amount, supply time, operating time, etc. of nitrogen gas to the gas chromatograph 2, if the threshold value for the catalyst function recovery process by the catalyst function recovery device 20 is exceeded, the process is performed. ..

(Gas chromatograph 2 (3 component simultaneous analyzer))
FIG. 5 is a schematic view showing the configuration of a three-component simultaneous analyzer which is an example of the gas chromatograph 2. First, the three-component simultaneous analyzer according to the present embodiment (hereinafter, also referred to as the present analyzer) detects three components composed of methane gas, carbon dioxide, and dinitrogen monoxide contained in the atmospheric gas as an analysis sample. It is a device for. Then, as shown in FIG. 5, the analyzer includes a first gas flow path A, a second gas flow path B located downstream of the first gas flow path A, and a third gas flow path. A first gas flow path between the path C, the first gas flow path A and the second gas flow path B, and between the first gas flow path A and the third gas flow path C. A switching valve 1400 for switching between a first state in which A and the second gas flow path B communicate with each other and a second state in which the first gas flow path A and the third gas flow path C communicate with each other. have. Hereinafter, each configuration related to this analyzer will be described.

First, the first gas flow path A is more than a carrier gas introduction unit 1010 for introducing a carrier gas, a sample introduction unit 1030 (injection port) for introducing an analysis sample, a carrier gas introduction unit 1010, and a sample introduction unit 1030. On the downstream side, a flow delay is caused depending on the type of the component contained in the analysis sample to obtain a first gas phase containing methane gas and a second gas phase containing carbon dioxide and dinitrogen monoxide. It has a first column 1060, which is arranged for the purpose.

In this analyzer, the carrier gas introduction unit 1010 described above preferably includes a carrier gas purification device 1020. By doing so, it is possible to improve the purity of the carrier gas introduced into the present analyzer. The high-purity nitrogen supply system 1 described above includes the functions of the carrier gas introduction unit 1010 and the carrier gas purification device 1020.
When the above-mentioned three components are detected using the carrier gas whose purity has been increased by the carrier gas purifying device 1020, the S / N ratio and detection of the analysis result are affected by the impurities contained in the carrier gas. It is possible to prevent the sensitivity from being lowered. Specifically, by using a carrier gas such as nitrogen gas or helium gas whose purity has been increased by the carrier gas purification device 1020, the detection peak of impurities contained in the carrier gas is the detection of the above three components to be analyzed. It is possible to prevent inconveniences such as overlapping with the peak and the above-mentioned impurities accumulated in the gas separation columns (first to third columns, etc.) described later increasing the detector noise and shortening the column life. be able to.

The carrier gas purification device 1020 described above is used to increase the purity of the carrier gas introduced into the analyzer, but from the viewpoint of dramatically improving the purity of the carrier gas, it is provided with a multi-stage carrier gas purification mechanism. It is preferable to have. Further, as a specific example of the carrier gas purification mechanism provided in the carrier gas purification device 1020, a gas purification filter such as a charcoal filter, a moisture trap, an oil mist trap, a hydrocarbon removal pipe filled with activated carbon, and a molecular sieve are filled. Examples thereof include a moisture absorbent tube, a trace oxygen / water removal tube filled with a resin (for example, manufactured by SUPELCO, OMI-4, etc.).

The sample introduction unit 1030 described above in this analyzer is provided with a septum (packing) in order to prevent inconveniences such as leakage of the analysis sample to the outside of the apparatus and mixing of outside air. Such a septum has a sealing property that can maintain the carrier gas pressure in the sample introduction section 1030 and can prevent the analysis sample from leaking to the outside of the apparatus even if the analysis is performed a plurality of times. It is not limited as long as it meets the conditions such as what it is doing. However, it is preferable to replace the septum with a new one with a maximum of 100 sample introductions as a guide, in order to prevent the above-mentioned inconvenience from occurring due to deterioration due to the multiple sample introductions.

Further, the sample introduction unit 1030 in this analyzer may have an automatic gas injection device (autosampler) from the viewpoint of reducing the labor and time required to acquire the measurement result.

A flow delay is caused on the downstream side of the carrier gas introduction section 1010 and the sample introduction section 1030 in the first gas flow path A of the present analyzer according to the type of the component contained in the analysis sample, and methane gas is introduced. There is a first gas phase containing and a first column 1060 arranged to obtain a second gas phase containing carbon dioxide and nitrous oxide. As described above, the first column 1060 causes a flow delay depending on the type of the component contained in the analysis sample. Therefore, when the analysis sample is passed through the first column 1060. , The retention time of the components contained in the analysis sample will be different.

Here, the column filler contained in the first column 1060 is preferably a styrene polymer fine powder or an effective activated carbon fine powder. Of these, effective activated carbon fine powder is preferable from the viewpoint of causing a clear difference in retention time between methane gas contained in the analysis sample and carbon dioxide and nitrous oxide. Here, specific examples of the effective activated carbon fine powder include zeolite powder containing a molecular sieve and activated carbon. When such effective activated carbon fine powder is used as a column filler, Unibeds C (manufactured by GL Science Co., Ltd.), activated carbon (SHINCARBON ST: Shinwa Kako), Molecular Sieve5A (manufactured by GL Science Co., Ltd.) and Molecular Sieve13X (manufactured by GL Science Co., Ltd.) A commercially available filler such as (manufactured by) may be used. Next, specific examples of the styrene polymer fine powder include commercially available porous polymer-based fillers such as Waters' Porapak Q, Porapak N, Porasil D and Porapak QS. Above all, a filler called Unibeds C (manufactured by GL Science Co., Ltd.) is preferable because it can cause a slight difference in the retention time between carbon dioxide and nitrous oxide.

Further, in the first column 1060 of this analyzer, methane gas having a molar mass of about 16 g / mol and carbon dioxide and dinitrogen monoxide having a molar mass of about 44 g / mol are in different gas phases. Since the configuration is arranged from the viewpoint of separating so as to be included, the packed column is used from the viewpoint of excellent separation of hydrocarbons and a large amount of samples that can be processed, rather than the theoretical number of stages per unit length of the column. It is preferable to have.

The column temperature of the first column 1060 is, for example, preferably 70 ° C. or higher and 170 ° C. or lower, and more preferably 80 ° C. or higher and 150 ° C. or lower. By doing so, it is possible to make a clear difference in the retention time between the first gas phase containing methane gas and the second gas phase containing carbon dioxide and nitrous oxide.

In addition to the first column 1060, the first gas flow path A in this analyzer is filled with styrene polymer fine powder from the viewpoint of suppressing column bleeding when the column is heated under high temperature conditions. It is preferable to further include a column encapsulated as an agent. Examples of such styrene polymer fine powders include commercially available porous polymer-based fillers such as Waters' Porapak Q, Porapak N, Porapak D and Porapak QS.

Further, the first gas flow path A is on the downstream side of the sample introduction section 1030 in the first gas flow path A, and on the upstream side of the first column 1060, the analysis result S / From the viewpoint of improving the N ratio, it is preferable to further include, for example, a water removal trap and an oxygen removal trap in order to remove water, oxygen and the like contained in the analysis sample.

Next, the second gas flow path B has a hydrogen flame ionization detector 1100 (hereinafter, also referred to as FID1100) for detecting the methane gas contained in the first gas phase described above at the downstream end. ing. The FID 1100 generally refers to a detector that measures the concentration of total hydrocarbons by measuring the ionic current generated when the gas to be measured is burned in a hydrogen flame. Therefore, the detector FID1100 is suitable for detecting hydrocarbons such as methane gas. For the detection of methane gas using FID1100, for example, a carrier gas is flowed at a flow rate of 20 mL / min or more and 40 mL / min or less, the temperature of FID1100 is set to 200 ° C. or more and 300 ° C. or less, and 1 mL of an analytical sample is introduced. When introduced from the part 1030, it can be detected with a holding time of about 2 minutes.

On the upstream side of the second gas flow path B from the FID 1100, a column containing styrene polymer fine powder as a filler is further included from the viewpoint of suppressing the occurrence of column bleeding when the column is heated under high temperature conditions. Is preferable. Examples of such styrene polymer fine powders include commercially available porous polymer-based fillers such as Waters' Porapak Q, Porapak N, Porasil D and Porapak QS.

Next, the third gas flow path C is located on the downstream side of the second column 1070 made of a packed column and the second column 1070, and is a type of component contained in the second gas phase. A third column 1080 consisting of a capillary column or a stainless steel column arranged to obtain a third gas phase containing carbon dioxide and a fourth gas phase containing dinitrogen monoxide, which causes a flow delay accordingly. From the thermal conductivity type detector 1200 for detecting carbon dioxide contained in the third gas phase, which is on the downstream side of the third column 1080, and the thermal conductivity type detector 1200. Also on the downstream side, it has an electron capture detector 1300 for detecting dinitrogen monoxide contained in the fourth gas phase.

The second column 1070 in the third gas flow path C is arranged to adjust the balance between the outlet pressure of the second gas flow path B described above and the outlet pressure of the third gas flow path C. ing. As described above, by having the second column 1070 in this analyzer, the influence of the valve shock generated when the flow path state is switched by using the switching valve 1400 on the baseline and the detected peak shape is reduced. can do. Specifically, it is possible to suppress the occurrence of inconveniences such as fluctuations in the baseline and fluctuations in the shape of the detected peak due to the valve shock. In order to accurately detect trace components such as nitrous oxide contained in the analytical sample introduced into this analyzer, it is particularly important to reduce the inconvenience caused by the valve shock described above as much as possible. The outlet pressure of the second gas flow path B refers to the gas pressure on the upstream side of the hydrogen flame ionization detector 1100 in the second gas flow path B, and is the third gas flow path. The outlet pressure of C refers to the outlet pressure of the third column 1080 in the third gas flow path C.

Here, in this analyzer, when the outlet pressure of the second gas flow path B is R2 and the outlet pressure of the third gas flow path C is R3, the second column 1070 causes R2 /. The value of R3 is preferably 1 or more and 40 or less, and more preferably 2 or more and 30 or less. By doing so, the two components of carbon dioxide and nitrous oxide can be detected at a high S / N ratio. The outlet pressure of the gas flow path is generally proportional to the diameter of the column.

The column filler contained in the second column 1070 is preferably a styrene polymer fine powder or an effective activated carbon fine powder. Of these, effective activated carbon fine powder is preferable from the viewpoint of causing a clear difference in retention time between methane gas contained in the analysis sample and carbon dioxide and nitrous oxide. Here, specific examples of the effective activated carbon fine powder include zeolite powder containing a molecular sieve and activated carbon. When such effective activated carbon fine powder is used as a column filler, commercially available fillers such as Unibeds C (manufactured by GL Science Co., Ltd.), activated carbon, Molecular Sieve 5A (manufactured by GL Science Co., Ltd.) and Molecular Sieve 13X (manufactured by GL Science Co., Ltd.) are used. May be used. Next, specific examples of the styrene polymer fine powder include commercially available porous polymer-based fillers such as Waters' Porapak Q, Porapak N, Porasil D and Porapak QS. In particular, a filler called Unibeds C (manufactured by GL Science Co., Ltd.) is preferable because it can cause a slight difference in the retention time between carbon dioxide and nitrous oxide.

The column temperature of the second column 1070 is, for example, preferably 70 ° C. or higher and 110 ° C. or lower, more preferably 75 ° C. or higher and 100 ° C. or lower, and even more preferably 80 ° C. or higher and 90 ° C. or lower.

Next, as described above, the third column 1080 in the third gas flow path C is a capillary column or a stainless steel column located downstream of the second column 1070, and is carbon dioxide and nitrous oxide. In order to cause a flow delay depending on the type of the component contained in the second gas phase including and to obtain a third gas phase containing carbon dioxide and a fourth gas phase containing nitrous oxide. It is arranged in. In general, a capillary column or a stainless steel column has a smaller column inner diameter and a higher number of theoretical plates than a packed column. Therefore, according to the third column 1080, it is possible to reduce the flow rate of the gas that has passed through the second column 1070. That is, according to the third column 1080, the outlet pressure of the third column 1080 can be controlled to be smaller than the outlet pressure of the second column 1070. As a result, in this analyzer, since the molecular weights are almost the same, there is a clear difference in the retention times of carbon dioxide and nitrous oxide, which were difficult to completely separate in the conventional analyzer. It becomes possible to make it. In other words, since the analyzer employs the configuration having the third column 1080, it is possible to detect each of carbon dioxide and nitrous oxide with high accuracy.

Here, the column inner diameters of the second column 1070 and the third column 1080 are such that the second column 1070 is 1 mm or more and 5 mm or less, and the third column 1080 is 0.1 mm or more and 1 mm or less. It is more preferable that the second column 1070 is 2 mm or more and 4.5 mm or less, and the third column 1080 is 0.2 mm or more and 0.8 mm or less. By doing so, both carbon dioxide and nitrous oxide components contained in the analytical sample introduced into the present analyzer can be detected with high S / N ratios, respectively.

The outlet flow rate of the third column 1080 (outlet flow rate in the third gas flow path C) in this analyzer is accurate even if the amount of dinitrogen monoxide, which is extremely low in the atmospheric gas, is on the order of ppb. From the viewpoint of good detection, when an analytical sample of 500 μL or more is introduced from the sample introduction unit 1030, the outlet flow rate is preferably configured to be 3 mL / min or more and 25 mL / min or less, preferably 3 mL / min or more. It is more preferable that the concentration is 20 mL / min or less.

Examples of the column packing material to be included in the third column 1080 include methylpolysiloxane and the like. The third column 1080 includes commercially available capillary columns such as HP-1 (manufactured by Agilent Technologies) and DB-1 (manufactured by Agilent Technologies), and Polymer Q (Porapac Q) having a size of about 80 to 100 mesh. A stainless steel column of about 2 to 5 m containing a porous polymer-based filler such as (manufactured by GL Science), Porapak N (manufactured by GL Science) and Porasil D (manufactured by GL Science) can be used. Above all, it is preferable to use PoraBOND Q from the viewpoint of improving the separation efficiency of carbon dioxide and nitrous oxide.

The column temperature of the third column 1080 is, for example, preferably 70 ° C. or higher and 170 ° C. or lower, and more preferably 80 ° C. or higher and 160 ° C. or lower. By doing so, it becomes possible to detect each of carbon dioxide and nitrous oxide with a high S / N ratio.

The third gas flow path C is a thermal conductivity type detector 1200 (hereinafter, also referred to as TCD1200) for detecting carbon dioxide contained in the above-mentioned third gas phase on the downstream side of the third column 1080. .)have. The TCD1200 generally refers to a detector that measures the concentration of the component to be measured by measuring the difference in thermal conductivity between the component to be measured and the carrier gas. Therefore, the detector TCD1200 is suitable for detecting components other than the components contained in the carrier gas. The carbon dioxide using TCD1200 is detected, for example, when the carrier gas is flowed at a flow rate of 35 mL / min or more and 45 mL / min or less, the holding time is about 4 to 5 minutes from the start of the outflow of the carrier gas. Can be done.

The third gas flow path C has an electron capture detector 1300 (hereinafter, also referred to as ECD1300) for detecting nitrous oxide contained in the above-mentioned fourth gas phase on the downstream side of the TCD1200. Have. In such an ECD1300, in general, the ion current flowing between the electrodes in the ECD1300 is reduced by combining the emitted electrons with the ionized carrier gas using β rays of ^{63 Ni and the parent electron substance.} It refers to a detector that measures the amount and measures the concentration of the parent electron substance. Therefore, the detector ECD1300 is suitable for detecting components such as nitro compounds. The detection of nitrous oxide using ECD1300 is performed, for example, when the carrier gas is flowed at a flow rate of 35 mL / min or more and 45 mL / min or less, the detection time is about 4 to 5 minutes from the start of the outflow of the carrier gas. can do.

Further, it is preferable that the third gas flow path C further has an additive gas introduction unit 1050 for introducing the additive gas on the downstream side of the TCD1200 and on the upstream side of the ECD1300. As described above, the detector ECD1300 utilizes the ion current (more specifically, the negative ion current) that flows between the electrodes by ionizing the carrier gas. Therefore, the carrier gas needs to contain a sufficient amount of components that are easily ionized. Therefore, by supplying gas components such as nitrogen gas and methane gas that are easily ionized from the added gas introduction unit 1050 into the third gas flow path C, nitrous oxide having an extremely low content in the atmospheric gas is supplied. It is possible to accurately detect the amount of gas in the order of ppb.

Next, a three-component simultaneous analysis method (hereinafter, also referred to as this analysis method) for detecting three components consisting of methane gas, carbon dioxide and dinitrogen monoxide contained in the atmospheric gas as an analysis sample using the above-mentioned analyzer. .) Will be described.

This analysis method includes a carrier gas introduction step of introducing a carrier gas into a gas flow path, a sample introduction step of introducing an analysis sample into a gas flow path filled with the carrier gas, and components contained in the analysis sample. From the first gas separation step of obtaining a first gas phase containing methane gas and a second gas phase containing carbon dioxide and dinitrogen monoxide, and from the components contained in the second gas phase, carbon dioxide It is a method having a second gas separation step of obtaining a third gas phase containing carbon and a fourth gas phase containing dinitrogen monoxide.

(Carrier gas introduction process)
In the present analysis method, first, the carrier gas is introduced into the first gas flow path A from the carrier gas introduction unit 1010 in the present analyzer shown in FIG. By doing so, all the gas components existing in the gas flow path in this analyzer can be replaced with the carrier gas. The flow rate of the carrier gas should be appropriately set by the flow rate regulator mounted on this analyzer in consideration of the relationship between the specifications of the column used and the retention time (retention time) of the component to be analyzed. However, it is preferably 20 mL / min or more and 40 mL / min or less from the viewpoint of causing a difference in the retention time of the three components composed of methane gas, carbon dioxide and dinitrogen monoxide.

In this analysis method, it is preferable to increase the purity of the carrier gas by using the carrier gas purification device 1020 before introducing the carrier gas into the first gas flow path A. That is, it is preferable that the carrier gas introduction step further includes a step of improving the purity of the carrier gas. By doing so, it is possible to prevent the S / N ratio and the detection sensitivity of the analysis result from being lowered due to the influence of impurities contained in the carrier gas. Specifically, by increasing the purity of the carrier gas in advance by the carrier gas purification device 1020, the detection peak of the contaminants contained in the carrier gas overlaps with the detection peak of the above three components to be analyzed. It is possible to prevent the above-mentioned impurities accumulated in the gas separation columns (first to third columns, etc.) described later from causing inconveniences such as increasing detector noise and shortening the column life. In particular, the purity of the carrier gas is preferably 99.999% or more, preferably 99.9999%, from the viewpoint of accurately detecting the amount of nitrous oxide having an extremely small content in the atmospheric gas on the order of ppb. It is more preferably 99.999999% or more, further preferably 99.999999% or more, and most preferably 99.999999% or more. If the upper limit of the purity of the carrier gas is about 99.999999%, it is possible to prevent the inconvenience caused by the above-mentioned impurities. The carrier gas is preferably helium gas or nitrogen gas having a purity of 99.999% or more. The carrier gas purification device 1020 described above preferably includes a multi-stage carrier gas purification mechanism from the viewpoint of improving the purity of the carrier gas as much as possible.

(Sample introduction process)
Next, in this analysis method, the analysis sample is introduced from the sample introduction unit 1030 into the gas flow path filled with the carrier gas. Specifically, 1 to 2 mL of atmospheric gas collected in a container such as a vial is introduced into the sample introduction unit 1030 using a gas tight syringe.

In this analysis method, from the viewpoint of reducing the labor and time required to acquire the measurement result, for example, an automatic gas injection device (autosampler) is used to inject atmospheric gas from the sample introduction unit 1030 to the gas flow path. It may be introduced.

(First gas separation step)
Then, in this analytical method, the analytical sample is passed through a first column 1060 for causing a flow delay depending on the type of component. By doing so, each component contained in the analysis sample can be separated into a first gas phase containing methane gas and a second gas phase containing carbon dioxide and nitrous oxide. From the viewpoint of suppressing the occurrence of column bleeding when the column is heated under high temperature conditions before and / or after passing the analysis sample through the first column 1060, Waters Corp.'s Polymer Q and Polymer are used. Commercially available porous polymer-based fillers such as N, Porasil D and Porapak QS may be passed through an encapsulated column. In this analysis method, each component contained in the first gas phase is held in the first column 1060 for a shorter time than each component contained in the second gas phase.

Next, the first gas phase containing methane gas is introduced into the second gas flow path B having the FID 1100, and after such a methane gas introduction step, the flow path state is switched by the switching valve 1400 to carbon dioxide and dioxide dioxide. The second gas phase containing nitrogen is introduced into a third gas flow path C having a thermal conductivity type detector 1200 and an electron capture type detector 1300. The flow path state is switched by the switching valve 1400 at an appropriate timing in consideration of the flow rate of the carrier gas, the holding time of each component by the first column 1060, and the like.

Next, the methane gas contained in the first gas phase introduced into the second gas flow path B is detected by the FID 1100. Regarding the first gas phase introduced into the second gas flow path B, from the viewpoint of suppressing the occurrence of column bleeding when the column is heated under high temperature conditions, Waters before introducing into the FID 1100. It is preferable to pass a column containing a commercially available porous polymer-based filler such as Porapak Q, Porapak N, Porasil D and Porapak QS manufactured by the same company.

(Second gas separation step)
Next, the second gas phase containing carbon dioxide and nitrous oxide introduced into the third gas flow path C is passed through the second column 1070 made of a packed column. Then, the second gas phase is passed through a third column 1080 made of a capillary column or a stainless steel column for causing a flow delay depending on the type of the component. By doing so, each component contained in the second gas phase can be separated into a third gas phase containing carbon dioxide and a fourth gas phase containing nitrous oxide. In this analysis method, each component contained in the third gas phase is held in the third column 1080 for a shorter time than each component contained in the fourth gas phase.

Then, carbon dioxide contained in the third gas phase obtained by passing through the third gas phase is detected by TCD1200, and then nitrous oxide contained in the fourth gas phase passing through TCD1200 is detected. Detected by ECD1300. Here, in this analysis method, from the detection of carbon dioxide by TCD1200 to the introduction of the fourth gas phase into ECD1300, that is, from the detection of carbon dioxide to the detection of nitrous oxide. From the viewpoint of accurately detecting the amount of nitrous oxide having an extremely small content in the atmospheric gas on the order of ppb, it is preferable to introduce methane gas or nitrogen gas into the gas flow path as an additive gas. Further, according to the findings obtained by the present inventor so far, even when nitrogen gas is used as a carrier gas, the detection sensitivity (and S / N) of nitrous oxide by ECD1300 is obtained by adding methane gas. The ratio) can be improved up to 10 times.

In the present embodiment, in one analysis, three components composed of methane gas, carbon dioxide and nitrous oxide contained in the atmospheric gas are simultaneously detected at a high S / N ratio even when the sample concentration is on the order of ppb. be able to. Further, according to the present embodiment, for example, it is possible to quantify three components composed of methane gas, carbon dioxide and nitrous oxide contained in atmospheric gas by one analysis.

Further, the gas chromatograph 2 (three-component simultaneous analyzer) capable of high-precision analysis as described above does not depend on a high-pressure cylinder, which requires careful handling and tends to be costly, and has high-purity nitrogen. A stable methane-free high-purity nitrogen gas (carrier gas) can be supplied from the supply system 1.

Although the embodiments of the present invention have been described above with reference to the drawings, these are examples of the present invention, and various configurations other than the above can be adopted. Further, in the flowchart used in the above description, a plurality of steps (processes) are described in order, but the execution order of the steps executed in each embodiment is not limited to the order of description. In each embodiment, the order of the illustrated steps can be changed within a range that does not hinder the contents. In addition, the above-described embodiments can be combined as long as the contents do not conflict with each other.

<Summary of features and effects of the embodiment>
The features and effects of the above embodiments are summarized as follows.
(1) The residual methane removing device 12 of the present embodiment includes a catalyst 121 using a metal oxide as a carrier, which ventilates a nitrogen gas from which oxygen has been separated and burns and removes the methane gas remaining in the nitrogen gas.
A catalyst function recovery device 20 that regenerates the function of the catalyst 121 by aerating oxygen through the catalyst 121,
To be equipped.
Examples of the metal oxide include aluminum oxide (alumina), copper oxide, and titanium oxide.
Oxygen can be recombined with the catalyst 121 (that is, metal oxide) consumed by burning methane gas, which is a nitrogen gas separated from oxygen, in an oxygen-deficient state. That is, the ability of the catalyst function of the catalyst 121 whose catalytic function has deteriorated can be regenerated.
As described above, Patent Document 1 has realized a technique for supplying high-purity nitrogen prepared by using compressed air, instead of supplying nitrogen that depended on a high-pressure gas cylinder. However, replacement of the catalyst 121 of the residual methane removing device 12 becomes expensive, and in many cases, the operation of the nitrogen cylinder is continued, and the operation of the nitrogen gas supply utilizing the above-mentioned purification technique has not been widely used. However, the technology for regenerating the catalyst 121 has always made it possible to construct a sound combustion catalyst environment, and it has become possible to construct a gas chromatograph analysis system 100 using high-purity nitrogen gas that does not use a high-pressure gas cylinder throughout the year. This contributes to a significant reduction in the amount of high-pressure gas cylinder used, and can stably perform high-precision gas analysis even in remote areas where it is difficult to transport the cylinder. The life of the catalyst combustion device for incinerating impurities can be extended, and the running cost can be reduced. Regarding the nitrogen gas supplied by the nitrogen supply device using the PSA method or other technology, the life of the combustion catalyst environment can be extended by introducing the technology for regenerating the catalyst 121 of the residual methane removal device 12 described above. This can be achieved, and the operational labor and cost of methane removal treatment can be reduced.

(2) The metal oxide is aluminum oxide.
Aluminium oxide (alumina) is suitable for the catalyst 121 from the viewpoint of catalytic ability, cost, availability, and stability (life).

(3) The catalyst function recovery device 20 supplies oxygen to the catalyst 121 by dry air.
If the gas aerated for the purpose of recovering the catalyst 121 is pure oxygen or a gas rich in oxygen, oxygen that has not been used for regeneration of the catalyst 121 may remain in the catalyst 121. Oxygen can generally be removed (filtered) relatively easily in the downstream process, but it is desirable to suppress it to a sufficient extent for catalyst regeneration if possible. At this time, the oxygen concentration may be controlled by synthetic air, but the catalyst 121 can be regenerated in a practical operation even with general dry air.
For example, in a system in which nitrogen gas is continuously supplied to a plurality of gas chromatographs 2, a desired catalyst recovery can be achieved by supplying dry air once / day to once / several days at 1 L / min to the catalyst. It was confirmed that there was no effect of residual oxygen in the downstream process.

(4) The high-purity nitrogen supply system 1 includes the above-mentioned residual methane removing device 12 and
A nitrogen generator 11 that supplies nitrogen gas to the residual methane removing device 12 and
The methane removing device is provided with a water / carbon dioxide removing device 13 (residual component removing device) that obtains the nitrogen gas from which the methane gas has been removed and removes at least water and carbon dioxide from the nitrogen gas.
High-purity nitrogen gas from which methane gas has been removed can be continuously obtained, and water and carbon dioxide generated when methane gas is burned and removed can be effectively removed. That is, high-quality nitrogen gas can be supplied to the gas chromatograph 2.

(5) A control device 30 for controlling the operation of the catalyst function recovery device 20 is provided.
The control device 30 controls the catalyst function recovery device 20 so as to aerate the oxygen and restore the function of the catalyst 121 at a predetermined timing.
By setting the timing as the recovery treatment period of the catalyst 121, it is possible to continuously supply methane-free high-purity nitrogen gas without substantially affecting the operation of the gas chromatograph 2.

(6) A control device 30 for controlling the operation of the catalyst function recovery device 20 is provided.
The control device 30 determines whether or not the function of the catalyst 121 is equal to or greater than the predetermined ability, and if it is determined that the function is less than the predetermined ability, the control device 30 controls the catalyst function recovery device 20 so as to restore the function of the catalyst 121.
For example, using a sensor that detects methane and a sensor that senses the combustion state by detecting moisture and carbon dioxide, it is determined whether or not the desired combustion is achieved, and the combustion state is not appropriate, that is, It is determined that the removal of methane is insufficient, and the catalyst 121 is recovered. It is also possible to recover the catalyst 121 in advance at a timing that does not affect the operation of the gas chromatograph 2 before the methane removing function (catalyst capacity) of the catalyst 121 becomes insufficient.

(7) When operating the catalyst function recovery device 20, the control device 30 disconnects the nitrogen gas supply path from the nitrogen generator 11 to the catalyst 121 and connects the oxygen supply path to the catalyst 121. For example, as such a configuration, there is a configuration in which a flow path switching valve or the like is provided in the supply path to control the flow path. With such a configuration, the catalyst capacity recovery process of the catalyst 121 can be performed by the catalyst function recovery device 20 by automatic switching.

(8) The gas chromatograph analysis system 100 includes the above-mentioned high-purity nitrogen supply system 1 and
A gas chromatograph 2 that receives nitrogen gas from the high-purity nitrogen supply system 1 and
To be equipped.
The gas chromatograph analysis system 100 can substantially always use methane-free high-purity nitrogen gas as a carrier gas. That is, by exchanging the catalyst 121, it is possible to suppress the suspension of operation of the gas chromatograph 2.

(9) A nitrogen generator 11 that purifies nitrogen gas obtained by separating oxygen from air, and a catalyst 121 using a metal oxide as a carrier that burns and removes methane remaining in the nitrogen gas purified by the nitrogen generator 11. A method for regenerating the catalytic function of the catalyst 121, which is executed in the high-purity nitrogen supply system 10 including the residual methane removing device 12 and the high-purity nitrogen supply system 10.
When the nitrogen gas is not ventilated to the catalyst 121, the catalyst 121 is ventilated with a gas containing oxygen to regenerate the catalytic function of the catalyst 121.

(10) In the catalyst function regeneration method, the metal oxide of the catalyst 121 is aluminum oxide.
Aluminium oxide (alumina) is suitable for the catalyst 121 from the viewpoint of catalytic ability, cost, availability, and stability (life).

(11) The method for producing high-purity nitrogen includes a raw gas acquisition step for acquiring nitrogen gas from which oxygen has been separated, and a raw gas acquisition step.
A methane removal step (S107) in which nitrogen gas is aerated through a catalyst 121 using a metal oxide as a carrier to burn and remove methane remaining in the nitrogen gas.
A catalyst function regeneration step (S200) in which the methane removal step is stopped, oxygen is aerated through the metal oxide through the catalyst, and the function as a catalyst is regenerated.
Have.
Oxygen can be recombined with the catalyst 121 (that is, metal oxide) consumed by burning methane gas, which is a nitrogen gas separated from oxygen, in an oxygen-deficient state. That is, the catalytic ability of the catalyst 121 whose catalytic function has deteriorated can be regenerated.

1 High-purity nitrogen supply system 2 Gas chromatograph 10 Nitrogen supply device 11 Nitrogen generator 12 Residual methane removal device 13 Moisture / carbon dioxide removal device (residual component removal device)
20 Catalyst function recovery device 30 Control device (control means)
100 Gas chromatograph analysis system 121 Catalyst 131 Moisture remover 132 Large capacity activated carbon (A)
133 Gas filter (moisture)
134 Gas filter (oxygen)
135 Carbon Dioxide Remover 136 Large Capacity Activated Carbon (B)

Claims (10)

A catalyst using a metal oxide as a carrier, which ventilates a nitrogen gas from which oxygen has been separated and burns and removes the methane gas remaining in the nitrogen gas.
A catalyst function recovery means for regenerating the function of the catalyst by aerating oxygen through the catalyst, and
A methane removal device equipped with. The methane removing device according to claim 1, wherein the metal oxide is aluminum oxide. The methane removing device according to claim 1 or 2, wherein the catalyst function recovering means aerates the oxygen through the catalyst with dry air. The methane removal device according to any one of claims 1 to 3,
A nitrogen generator that supplies the nitrogen gas to the methane removal device,
A residual component removing device that obtains nitrogen gas from which the methane gas has been removed by the methane removing device and removes at least water and carbon dioxide from the nitrogen gas.
High purity nitrogen supply system with. Further, a control means for controlling the operation of the catalyst function recovery means is provided.
The high-purity nitrogen supply system according to claim 4, wherein the control means controls the catalyst function recovery means so as to supply the oxygen and restore the function of the catalyst at a predetermined timing. Further, a control means for controlling the operation of the catalyst function recovery means is provided.
The control means determines whether or not the function of the catalyst is equal to or higher than a predetermined ability, and if it is determined that the function is less than the predetermined ability, the control means controls the catalyst function recovery means so as to restore the function of the catalyst. The high-purity nitrogen supply system according to 4 or 5. 5. The control means may disconnect the supply path of the nitrogen gas from the nitrogen generator to the catalyst and connect the supply path of the oxygen to the catalyst when operating the catalyst function recovery means. 6. The high-purity nitrogen supply system according to 6. The high-purity nitrogen supply system according to any one of claims 4 to 7.
A gas chromatograph that receives nitrogen gas from the high-purity nitrogen supply system,
A gas chromatograph analysis system. A nitrogen generator that purifies nitrogen gas that separates oxygen from air,
It is carried out in a high-purity nitrogen supply system including a residual methane removal device equipped with a catalyst using a metal oxide as a carrier, which burns and removes methane remaining in the nitrogen gas purified by the nitrogen generator. A method for regenerating the catalytic function of the catalyst.
A catalyst function regeneration method for regenerating the catalytic function of the catalyst by aerating a gas containing oxygen through the catalyst when the nitrogen gas is not ventilated to the catalyst. The catalyst function regeneration method according to claim 9, wherein the metal oxide is aluminum oxide.

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