JP4602202B2 - Gas processing method and gas processing apparatus - Google Patents

Description

  The present invention relates to a gas processing method and a gas processing apparatus, and more particularly to a technique that is effective when applied to a gas separation technique for separating nitrogen contained in a gas to be processed by using a difference in adsorption speed to an adsorbent.

As one of gas separation methods for removing nitrogen contained in natural gas, city gas, methane gas, etc., for example, as described in Patent Document 1 or Patent Document 2, a pressure swing adsorption separation method using an adsorbent ( PSA) is known.
Japanese Patent Publication No. 7-32857 JP 2000-31824 A

  The methane gas purification method described in Patent Document 1 is intended to “provide a new method that can easily and reliably purify methane gas”, and “removes nitrogen in methane gas by an adsorption method”. In the refining method for obtaining high-purity methane gas, mordenite-type zeolite is used to adsorb and remove nitrogen in the methane gas ”. In this method, it is said that “nitrogen as an impurity can be easily removed to an extremely small amount without adsorbing methane gas even under normal pressure conditions in a range of −20 ° C. or lower and −150 ° C.” The sodium salt type mordenite type zeolite can be used as it is, but more preferable results can be obtained by using a single or mixture of sodium cation exchanged with a divalent cation such as calcium, barium or iron. " Yes.

  Patent Document 2 describes the purpose of “selectively adsorbing and separating non-combustible gases such as nitrogen and carbon dioxide from a mixed gas containing methane as a main component and efficiently recovering high-purity methane”. Such a molecular sieving carbon is disclosed as “a molecular sieving carbon capable of separating methane and nitrogen with high efficiency”.

  However, in the technique described in Patent Document 1, satisfactory methane and nitrogen separation performance cannot be obtained unless the temperature of the mordenite zeolite as the adsorbent is cooled to -20 ° C or lower. As described in the same document, after nitrogen is adsorbed on the adsorbent, it is necessary to regenerate the adsorbent to recover the necessary adsorption capacity, and the temperature of the adsorbent is heated to 100 ° C. or higher for the regeneration treatment. There is a need to. If the treatment temperature at the time of nitrogen adsorption is −20 ° C. or less and the treatment temperature at the time of regeneration is 100 ° C. or more, in the PSA method in which the separation treatment is repeatedly performed by adsorption and regeneration, In addition to the heating time, a cooling time for cooling the adsorbent is required, and there is a problem that the processing cycle becomes long and the processing throughput is lowered. In addition to the energy for heating, energy for cooling is necessary, and the energy to be input must be considerably large. Furthermore, not only a heating device but also a cooling device is required, and there is a problem that the cost of the processing device increases.

  Further, in the technique described in Patent Document 2, molecular sieving carbon (molecular sieve charcoal) is used as an adsorbent. The molecular sieving carbon needs to be manufactured by precisely controlling the pore diameter, and generally has a know-how factor to the manufacturing conditions and is difficult to manufacture. For this reason, the supply manufacturers are also limited and it is difficult to obtain them.

  An object of the present invention is to provide a gas separation method or separation apparatus that can separate nitrogen without cooling the adsorbent using an adsorbent that can be easily obtained or manufactured.

  The invention disclosed in this specification is as follows. That is, in the gas treatment method of the present invention, mordenite-type zeolite that has been heat-treated in advance is used as the adsorbent. This pre-heated mordenite-type zeolite was discovered by the inventors in the adsorbent search and has sufficient nitrogen adsorption performance even at room temperature without cooling. The present invention has been made on the basis of knowledge obtained in the adsorbent search by the present inventors. According to the present invention, since mordenite-type zeolite that has been heat-treated in advance is used as the adsorbent, nitrogen contained in the gas to be treated such as methane gas can be separated by utilizing sufficient nitrogen adsorption performance without cooling the adsorbent. be able to. Mordenite-type zeolite is not difficult to manufacture like molecular sieve carbon (molecular sieve charcoal), and can be easily obtained or manufactured, and pre-heat treatment can be easily performed using a general electric furnace or the like. Is possible.

  The present invention will be specifically disclosed as follows. That is, the gas separation method of the present invention is a gas separation method in which the concentration of nitrogen contained in the gas to be treated is changed by supplying and passing the gas to be treated containing nitrogen through a column filled with an adsorbent. And a step of starting the supply of the gas to be processed from the gas supply side of the column, and a gas flowing out from the gas discharge side of the column after a predetermined breakthrough time has elapsed from the start of the supply of the gas to be processed. And using a mordenite-type zeolite that has been heat-treated in advance as the adsorbent, and in the step of starting the supply of the gas to be treated and the step of collecting the gas flowing out from the column, The processing is performed without cooling. According to the present invention, since the adsorption process can be performed without cooling the adsorbent, the adsorption and regeneration process time can be shortened and the process throughput can be improved. Moreover, the input energy for cooling can be reduced. Furthermore, no cooling device is required, and the device cost can be reduced. Moreover, the mordenite type zeolite used in the present invention can be easily obtained or manufactured, and there is no difficulty in obtaining the adsorbent.

  In the invention, the adsorbent may be regenerated by reducing the pressure in the column or purging the column with a carrier gas.

  Further, the heat treatment applied in advance to the mordenite-type zeolite as the adsorbent can be performed at a temperature of 600 ° C. or higher and lower than 800 ° C. in a predetermined gas atmosphere. This is based on the findings of the present inventors' investigation that the effect of improving the nitrogen adsorption performance at room temperature is not seen at 600 ° C. or lower, and that the nitrogen adsorption performance at room temperature is lowered by heat treatment at a temperature of 800 ° C. or higher. Based. It can be inferred that the decrease in nitrogen adsorption performance at room temperature due to heat treatment at 800 ° C. or higher is due to the destruction of the structure of the mordenite zeolite.

  In addition, examples of the predetermined gas include nitrogen, air, and argon, or a combination thereof. According to the experimental study by the present inventors, the development of nitrogen adsorption performance at room temperature was observed by heat treatment of mordenite-type zeolite containing these gases as an atmosphere.

  In the above-described invention, the adsorbent may be Na-mordenite type zeolite. Furthermore, a part of Na ions of the Na-mordenite type zeolite may be substituted with Ag ions or other monovalent cations.

  The gas to be treated can include methane, natural gas, city gas, and digestion gas.

  In the above description, the invention relating to the gas processing method has been described, but the present invention can also be understood as a gas processing apparatus. That is, the gas processing apparatus of the present invention includes a column filled with an adsorbent, a gas supply means for supplying a gas to be processed containing nitrogen to the gas supply side of the column, and a gas discharge side of the column. A mordenite-type zeolite that has been heat-treated in advance as the adsorbent, and starts supplying the gas to be treated without cooling the adsorbent, It can be understood that the gas flowing out from the discharge side of the column after the passage of the overtime is collected by the gas collection mechanism. Further, the invention of the gas processing apparatus may further include a mechanism for reducing the pressure in the column or supplying a purge gas into the column to regenerate the adsorbent in the column. In addition, the treatment temperature of the adsorbent, heat treatment conditions such as treatment atmosphere gas, the adsorbent can be Na-mordenite type zeolite, a part of Na ions can be replaced with Ag ions or other monovalent cations, the gas to be treated Can contain methane, natural gas, city gas, digestion gas, etc., as in the case of the gas treatment method.

  According to the invention of the present application, it is possible to provide a gas separation method or a separation apparatus that can separate nitrogen without cooling the adsorbent using an adsorbent that can be easily obtained or manufactured.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a conceptual diagram showing an example of a gas processing apparatus according to an embodiment of the present invention. The gas processing apparatus of the present embodiment includes a column 10, an adsorbent 20 filled in the column 10, a cylinder 30 filled with methane gas containing nitrogen as a gas to be processed, and an exhaust gas after processing. And a collection cylinder 40 for storage. As shown, the cylinder 30 is connected to the gas inlet of the column 10 via the mass flow meter MFC1 and the valve V1. A collection cylinder 40 is connected to the gas outlet of the column 10 via a valve V2. The gas to be treated is flow-controlled by the MFC 1 and supplied from the cylinder 30 to the column 10. The exhaust gas from the column 10 when the valve V2 is closed is discharged to the exhaust port EXT. Although not shown, the cylinder 30 is provided with pressure adjusting means such as a regulator, and of course gas is supplied under a constant pressure.

  The column 10 is a cylindrical container formed of a chemically and mechanically stable material such as stainless steel, and the gas to be treated passes through the column 10. Since the gas treatment in the present embodiment is performed under atmospheric pressure, the column 10 is not required to have a mechanical strength more than necessary. However, when the regeneration process of the adsorbent 20 is realized by reduced pressure exhaust as will be described later, the mechanical strength enough to withstand a reduced pressure state below atmospheric pressure and the sealing property enough to prevent outside air from entering. Required. Examples of the shape of the column 10 include a cylindrical shape having a diameter of 3.13 mm (1/8 inch) and a length of 30 cm. The column material or column shape exemplified here is merely an example, and any material, size, and shape can be applied. For example, a column may be comprised with plastics, such as an acryl, and shapes, such as prismatic shape, may be sufficient. However, since it is necessary to sufficiently perform gas adsorption along the gas flow, a certain column length with respect to the column diameter is required. Although omitted in the drawing, an appropriate heating means may be provided for the regeneration process of the adsorbent 20. However, the gas processing apparatus according to the present embodiment does not include a cooling means for cooling the adsorbent 20. As will be described later, even if the adsorbent 20 is not cooled, the adsorbent 20 of the present embodiment has a sufficient nitrogen adsorbing ability.

The adsorbent 20 is mordenite-type zeolite that has been heat-treated in advance. Mordenite zeolite is generally _{W 2 O · Al 2 O 3} · 10SiO 2 · XH 2 O ( provided that W = Na, Ca, K, etc., X = undefined) has a chemical composition of, those W = Na is Na -Mordenite type zeolite. A part of Na may be replaced with a monovalent cation such as Ag, which will be described later. Mordenite-type zeolite has pores suitable for adsorption of nitrogen molecules because of its crystal structure.

  The heat treatment of the mordenite-type zeolite can be performed by a general electric furnace or the like. An example of the heat treatment condition is 600 ° C. or higher and lower than 800 ° C., preferably 700 ° C. to 760 ° C. Moreover, the heat processing time can illustrate the range of 1 hour-8 hours (holding time). In the heat treatment, the rate of temperature increase / decrease is not particularly limited, but in the experimental example described later, it was set to 3 ° C./min. Examples of the heat treatment atmosphere include nitrogen, argon, and air.

  As the cylinder 30 and the collection cylinder 40, normal gas cylinders can be used. The methane gas sealed in the cylinder 30 contains nitrogen. There is no particular limitation on the amount of nitrogen contained. In addition, although methane gas is illustrated here as a to-be-processed gas, you may be different gas from methane gas, such as natural gas, city gas, and digestion gas. The collection cylinder 40 is previously evacuated to a reduced pressure and applied to the present apparatus. Since the internal pressure of the column 10 at the time of gas treatment is atmospheric pressure, the exhaust gas can be collected in the collection cylinder 40 using the differential pressure without providing a special gas supply means.

  In the above example, the cylinder 30 and the flow rate control means such as MFC associated therewith are shown as supply means for the gas to be processed. However, the gas supply means is not limited to means using these cylinders, and any gas supply means can be applied as long as gas supply is performed at a constant flow rate. For example, the gas to be treated may be supplied from a natural gas plant. Moreover, the collection cylinder 40 is illustrated as a gas collection means after a process. However, the collecting means is not limited to using a cylinder, and any gas collecting means can be applied as long as the exhaust gas from the column 10 can be collected at an appropriate timing. Although not shown, a carrier gas may be supplied together with the gas to be processed. Examples of the carrier gas include rare gases such as helium and argon. Further, when regeneration of the adsorbent 20 in the column 10 to be described later is performed by reduced pressure exhaust, a vacuum pump is provided.

  FIG. 2 is a flowchart showing an example of the processing method of the gas processing apparatus of the present embodiment. It is assumed that the adsorbent 20 in the column 10 has been regenerated as a precondition for the start of processing. When the process is started, the valve V1 is opened and supply of the gas to be processed is started (step 101). The valve V1 is opened for a certain time, and the valve V1 is closed after a certain time has elapsed. An example of the fixed time is 10 seconds. In the case of using a carrier gas, the column 10 is filled with the carrier gas, and the carrier gas is allowed to flow at a predetermined flow rate in advance. The carrier gas can be exemplified by helium, and the flow rate can be exemplified by a range of 10 to 50 ml / min, preferably 25 ml / min.

  When the valve V1 is opened, the gas to be processed moves through the column 10, and nitrogen in the gas to be processed is adsorbed by the adsorbent 20 accordingly. The adsorbent 20 is not cooled and is at room temperature. When the gas to be treated reaches the outlet of the column 10, the exhaust gas from the outlet contains methane gas. The time from when the gas to be treated is supplied until it reaches the column outlet is referred to as breakthrough time. The breakthrough time varies depending on processing parameters such as the column size, the supply flow rate of the gas to be processed, and the column temperature, but becomes constant when the processing parameters are fixed, and is generally about 100 to 200 seconds.

  A phenomenon when the gas to be processed passes through the column 10 will be described in detail. The heat-treated mordenite zeolite, which is the adsorbent 20 of the present embodiment, does not adsorb methane (or has a high desorption rate even if adsorbed), while adsorbs nitrogen (low desorption rate). For this reason, the gas to be processed that is discharged immediately after the breakthrough time does not contain nitrogen, even if it is contained, it is a very small amount of nitrogen, and if the exhaust gas is collected only for a short period after the breakthrough time, Methane gas with extremely low nitrogen content can be obtained. That is, nitrogen is separated from methane gas.

  FIG. 3 is a graph showing a typical example of a time profile of the methane partial pressure and the nitrogen partial pressure of the gas discharged from the column outlet. In FIG. 3, the vertical axis and the horizontal axis indicate partial pressure and time, respectively. The number of molecules of methane and nitrogen contained in the exhaust gas was measured with a mass spectrometer, and the partial pressure at that time was calculated from the measured number of molecules. The broken line is the partial pressure of methane gas, and the solid line is the partial pressure of nitrogen gas. In addition, in the broken line graph which shows methane partial pressure, the display is abbreviate | omitted about the peak part which protruded from the vertical axis | shaft range. The time when the valve V1 is opened is set to zero.

In Figure 3, immediately after the breakthrough time T ₁ methane partial pressure rises rapidly. On the other hand, the first increase in the nitrogen partial pressure and the elapsed time further after T ₂ of the breakthrough time T ₁ is is observed. This indicates that when the gas to be processed passes through the column 10, nitrogen is adsorbed by the adsorbent 20 while methane is not adsorbed by the adsorbent 20 (or immediately desorbs even if adsorbed). . That is, even when methane and nitrogen are simultaneously supplied into the column 10 as the gas to be processed, the phenomenon that the nitrogen reaches the column outlet later is reflected, reflecting the difference in the adsorption / desorption rate to the adsorbent 20. Using this phenomenon, by opening only the valve V2 for a time T _2, so that (even very containing nitrogen traces as containing or) can collect on the collecting cylinder 40 of high-purity methane gas containing no nitrogen. That is, when there is a time T ₂ of the difference between the rise time of the rise time and the nitrogen partial pressure of methane partial pressure as shown in FIG. 3, it is possible to separate nitrogen from methane.

FIG. 4 shows experimental results similar to those in FIG. 3 when mordenite-type zeolite not subjected to heat treatment is used as the adsorbent. It is shown for comparison with FIG. As shown in FIG. 4, the rise time of the rise time and the nitrogen partial pressure of methane partial pressure is about the same time, the time T ₂ in FIG. 3 does not exist. That is, if mordenite-type zeolite not subjected to heat treatment is used as the adsorbent, nitrogen cannot be separated.

Returning to FIG. 2, the description will be continued. As described above, since very low methane gas is obtained the nitrogen concentration during the breakthrough time T ₁ of the elapsed time T _2, waiting for breakthrough time (step 102), performs the collection of the exhaust gas (step 103 ). The exhaust gas is collected by opening the valve V2 and introducing the exhaust gas to the collection cylinder 40. Opening time of the valve V2 is a period or shorter period than time T _2. Since the time T ₂ are varied by the processing parameters must be optimized for each processing parameter.

  Next, regeneration processing of the adsorbent 20 is performed (step 104). For the regeneration treatment, any one of a method of purging the inside of the column 10 with a rare gas or a method of evacuating the column 10 can be adopted. In the purging method, the methane partial pressure and the nitrogen partial pressure in the column 10 are reduced, so that the nitrogen adsorbed on the adsorbent 20 is naturally released. In the method of evacuating under reduced pressure, the inside of the column 10 is evacuated to forcibly remove the adsorbed nitrogen. Whichever method is used, heating the adsorbent 20 is effective because the nitrogen is quickly released.

  When the regeneration of the adsorbent 20 is completed, the process returns to step 101 and the same processing is repeated. By such a method, nitrogen can be separated from methane gas. In the present embodiment, the nitrogen separation process as described above is performed without cooling the adsorbent 20. For this reason, a cooling device is not required and input energy can be reduced. When the adsorbent 20 is heated during the regeneration process, the adsorbent 20 is not cooled, so the temperature can be quickly raised and the processing time can be shortened. Further, the adsorbent 20 of the present embodiment is obtained by simply heat-treating a mordenite-type zeolite that can be easily obtained. For this reason, it is not necessary to use molecular sieving carbon which is difficult to obtain.

  Next, an experimental result on how the nitrogen separation performance changes depending on the conditions of the heat treatment applied to the adsorbent 20 will be described.

  FIG. 5 is a series of graphs showing changes in nitrogen separation performance when the treatment temperature of the heat treatment applied to the adsorbent is changed. Each graph is a graph showing the methane partial pressure and the nitrogen partial pressure as in FIG. (A) is a case without heat treatment, (b) is a graph when heat treatment is performed at 600 ° C., (c) is 700 ° C., (d) is 760 ° C., and (e) is heat treatment at 800 ° C., respectively. In any of the cases (a) to (e), the adsorbent is Na-mordenite zeolite, the heat treatment time is 1 hour (however, only 4 hours at 600 ° C.), and the heat treatment atmosphere is nitrogen. As in the case of FIG. 3, it was obtained by calculation from the number of molecules measured with a mass spectrometer. The temperature of the adsorbent during each measurement is room temperature.

(A) and (e) in the absence of time _{T 2} in FIG. 3 in FIG. 5, there is a time _{T 2} in the reversed (b) ~ (c) Figure 3. That is, if the Na-mordenite-type zeolite is not subjected to heat treatment, nitrogen separation performance at room temperature is not exhibited. However, if heat treatment is performed at 800 ° C., the heat treatment temperature is too high and the nitrogen separation performance at room temperature disappears. In the case of Na-mordenite type zeolite, it can be said that the range required for the heat treatment temperature is 600 ° C. or higher and lower than 800 ° C. (C) and (d) at time T ₂ is considerably longer, it can be seen that suitable nitrogen separation performance when subjected to the heat treatment in the range of 700 ° C. to 760 ° C. is obtained. In addition, two peaks are observed in the graph of methane partial pressure in the heat treatment at 700 ° C. of (c). This is because the adsorbent of the present embodiment has a structure or state of an adsorbent having almost the same adsorbing capacity for methane (or desorption rate of adsorbed methane) and lower methane adsorbing capacity (or adsorption). Shows that there is at least two structures or states of the adsorbent structure or state that have a higher methane desorption rate, and that the structure or state has a lower methane adsorption capacity as the heat treatment temperature increases. I can understand. In other words, by heat-treating the adsorbent, the methane adsorption capacity decreases, but the nitrogen adsorption capacity maintains the state before the heat treatment (or the adsorption capacity becomes higher) in the adsorbent, causing such a change. It can be said that the nitrogen separation of the present embodiment can be realized by using the adsorbent. Although not shown in the drawings, the present inventors conducted experiments at 720 ° C. and 740 ° C., and obtained results similar to (d) in both results at 720 ° C. and 740 ° C.

  6 and 7 are a series of graphs showing changes in nitrogen separation performance when the treatment time of the heat treatment applied to the adsorbent is changed. Each graph is a graph showing the methane partial pressure and the nitrogen partial pressure as in FIG. The heat treatment temperature in FIG. 6 is 600 ° C., (a) is for 4 hours, (b) is for 8 hours, and (c) is for 12 hours. The heat treatment temperature in FIG. 7 is 700 ° C., (a) is one hour, (b) is four hours, and (c) is eight hours. 6 and 7, the adsorbent is Na-mordenite type zeolite and the heat treatment atmosphere is nitrogen. As in the case of FIG. 3, it was obtained by calculation from the number of molecules measured with a mass spectrometer. The temperature of the adsorbent during each measurement is room temperature.

6 and 7, the change in the time T ₂ in FIG. 3, no significant difference to the extent that the heat treatment time exceeds 1 hour. Therefore, it can be seen that the nitrogen separation performance of the heat-treated Na-mordenite zeolite is not very sensitive to the heat treatment time of 1 hour or more, and the heat treatment temperature contributes more greatly. In other words, a heat treatment time of 1 hour is sufficient, and it can be said that there is no particular adverse effect even if the heat treatment is performed for a longer time. The heat treatment time is suitably in the range of 1 hour to 12 hours.

  As described above, it was shown that if Na-mordenite zeolite was subjected to heat treatment, nitrogen could be separated from methane gas using this as an adsorbent. Here, the treatment temperature during the heat treatment is important, and it is necessary to perform the heat treatment in a temperature range of 600 ° C. or higher and lower than 800 ° C. The heat treatment temperature is preferably in the range of 700 ° C to 760 ° C. The heat treatment time is suitably in the range of 1 to 12 hours.

  Although the present invention has been specifically described above, it is needless to say that the present invention is not limited to the above-described embodiment and can be variously modified without departing from the gist thereof.

For example, in the above-described embodiment, Na-mordenite type zeolite is exemplified as an example of the mordenite type zeolite. However, a part of Na is a monovalent cation such as Ag (Group 1A or Group 1B element ion or monovalent cation). ) May be substituted. FIG. 8 is a graph showing methane partial pressure and nitrogen partial pressure similar to those in FIG. 3 when mordenite-type zeolite in which a part of Na is substituted with Ag is subjected to heat treatment and used as an adsorbent. The presence of 3 similar time T ₂ is observed in FIG. 8 shows that there is a nitrogen separation performance at room temperature.

Moreover, in above-mentioned embodiment, the case where the heat processing performed to Na-mordenite type | mold zeolite was performed in nitrogen atmosphere was illustrated. However, the heat treatment applied to the Na-mordenite-type zeolite is not necessarily performed in a nitrogen atmosphere, and can be performed in a rare gas such as argon, or air containing nitrogen as a main component. FIG. 9 is a graph showing the methane partial pressure and nitrogen partial pressure in the same manner as in FIG. 3 when the Na-mordenite-type zeolite is heat-treated in an air atmosphere and used as an adsorbent. FIG. 10 is a graph showing the methane partial pressure and nitrogen partial pressure similar to those in FIG. 3 when heat treatment of the Na-mordenite type zeolite is performed in an argon atmosphere and this is used as an adsorbent. In any case of FIGS. 9 and 10, the presence of 3 similar time T ₂ was observed, indicating that there is a nitrogen separation performance at room temperature.

It is the conceptual diagram which showed an example of the gas processing apparatus which is one embodiment of this invention. It is the flowchart which showed an example of the processing method of the gas processing apparatus which is one embodiment of this invention. It is the graph which showed the typical example of the time profile of the methane partial pressure of the gas discharged | emitted from a column exit, and nitrogen partial pressure. It is an experimental result similar to FIG. 3 at the time of using the mordenite type zeolite which does not heat-process as an adsorbent. It is a series of graphs showing changes in nitrogen separation performance when the treatment temperature of the heat treatment applied to the adsorbent is changed, (a) is the case without heat treatment, (b) is 600 ° C., (c) is 700 ° C. (D) is a graph at the time of heat-processing at 760 degreeC, (e) is each at 800 degreeC. It is a series of graphs showing changes in nitrogen separation performance when the heat treatment temperature applied to the adsorbent is 600 ° C. and the treatment time is changed. (A) is heat treated for 4 hours, (b) is heat treated for 8 hours, and (c) is heat treated for 12 hours. It is a series of graphs showing changes in nitrogen separation performance when the heat treatment temperature applied to the adsorbent is 700 ° C. and the treatment time is changed. (A) is heat treated for 1 hour, (b) is heat treated for 4 hours, and (c) is heat treated for 8 hours. It is the graph which showed the methane partial pressure and nitrogen partial pressure similar to FIG. 3 at the time of heat-processing to the mordenite type zeolite which substituted some Na for Ag, and making this into an adsorbent. It is the graph which showed the methane partial pressure and nitrogen partial pressure similar to FIG. 3 at the time of heat-processing to Na-mordenite type | mold zeolite in an air atmosphere, and making this into an adsorbent. It is the graph which showed the methane partial pressure and nitrogen partial pressure similar to FIG. 3 at the time of heat-processing to Na-mordenite type | mold zeolite in argon atmosphere, and making this into an adsorbent.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Column, 20 ... Adsorbent, 30 ... Cylinder, 40 ... Collection cylinder, EXT ... Exhaust port, MFC1 ... Mass flow meter, T1 ... Breakthrough time, T2 ... Time, V1 ... Valve, V2 ... Valve

Claims (8)

Nitrogen-containing methane, natural gas, city gas, or digestion gas is used as the gas to be treated, and the gas to be treated is supplied to and passed through a column filled with an adsorbent, so that the nitrogen contained in the gas to be treated A gas separation method for changing the concentration,
Starting the supply of the gas to be processed from the gas supply side of the column;
After the passage of a predetermined breakthrough time, which is the time from the start of supply of the gas to be treated until the methane in the gas to be treated reaches the breakthrough point, the nitrogen gas in the gas to be treated is continuously adsorbed from the column. Collecting methane, natural gas, city gas or digestion gas from which nitrogen is absorbed and removed ,
Have
Using the mordenite-type zeolite that has been previously heat-treated at a temperature of 600 ° C. or higher and lower than 800 ° C. in an atmosphere of a predetermined gas made of nitrogen, argon, or a combination thereof as the adsorbent, A gas treatment method comprising: performing a treatment without cooling the adsorbent in the step of collecting methane, natural gas, city gas, or digestion gas from which nitrogen has been adsorbed and removed from the column.   The gas processing method according to claim 1, further comprising a step of regenerating the adsorbent with a configuration in which the inside of the column is depressurized or a configuration in which the inside of the column is purged with a carrier gas. The gas treatment method according to claim 1 or 2 , wherein the adsorbent is Na-mordenite type zeolite. Gas treatment method according to claim 3, wherein a part of Na ions in the Na- mordenite zeolite is characterized in that it is substituted by Ag ions other monovalent cations. A column filled with an adsorbent;
Nitrogen-containing methane, natural gas, city gas or digestion gas as a gas to be processed, and a gas to be processed supplying means for supplying the gas to be processed to the gas supply side of the column;
A gas collection mechanism connected to the gas discharge side of the column,
As the adsorbent, using a mordenite-type zeolite that has been previously heat-treated at a temperature of 600 ° C. or higher and lower than 800 ° C. in an atmosphere of a predetermined gas composed of nitrogen, argon, or a combination thereof ,
Without cooling the adsorbent, the feed was started the gas to be treated, after a predetermined breakthrough time is a time until methane treated gas reaches the breakthrough point, the treated gas while continuing the adsorption of nitrogen, flows out from the discharge side of the column, methane nitrogen is adsorbed and removed, natural gas, gas processing device for catching city gas or digester gas into the gas collecting mechanism. Wherein the column in a vacuum, or gas processing apparatus according to claim 5, wherein the purge gas supplying further comprises a mechanism for reproducing the adsorbent in the column to the column. The gas processing apparatus according to claim 5 or 6 , wherein the adsorbent is Na-mordenite type zeolite. The gas processing apparatus according to claim 7, wherein a part of Na ions of the Na-mordenite type zeolite is substituted with Ag ions or other monovalent cations.

Images