JP4529285B2 - Gas separation membrane device and operation stop method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a gas separation membrane device and a method for stopping operation of the gas separation membrane device. In particular, when the mixed gas to be supplied contains moisture, the moisture remaining in the gas separation membrane device during the operation stop is adsorbed or condensed on the membrane surface, and the membrane performance is temporarily lowered when the operation is resumed. The present invention relates to a gas separation membrane device having a function of preventing and a method of stopping operation of the gas separation membrane device.
[0002]
[Prior art]
Gas separation membrane devices using selective gas permeable membranes are used in many fields such as dehumidification of air, production of enriched nitrogen and enriched oxygen from air, separation, recovery, and purification of inorganic and organic gases. ing. Gas separation membrane devices are usually miniaturized using hollow fiber membranes, are highly efficient, economical, easy to operate, and can be operated or stopped as necessary. Therefore, the target gas is often manufactured, separated, recovered, purified, etc. on-site and connected so as to be directly supplied to an apparatus using the gas.
[0003]
When producing, separating, recovering and purifying a target gas with a gas separation membrane device, it is desired that a gas having a target purity and flow rate can be obtained with a predetermined membrane performance immediately after the start of operation. When operating by connecting a gas separation membrane device and a device that uses gas, the gas separation membrane device is operated or stopped along with the operation or stoppage of the device that uses gas. It is particularly important to obtain a gas with the desired purity and flow rate immediately after. However, when the gas separation membrane device is stopped for a certain period of time and restarted, the predetermined membrane performance cannot be obtained immediately after starting, and the operation is wasted until the predetermined membrane performance is restored. Had occurred. In particular, when the mixed gas to be supplied contains moisture, when the operation of the gas separation membrane device is stopped, the moisture remaining in the device is adsorbed or condensed on the membrane surface due to temperature change etc. There was a problem of lowering.
[0004]
In the gas separation membrane, separation is performed by the difference in gas permeability (selective permeability) with respect to the membrane. That is, the gas is separated because the permeation speed at which the gas permeates the membrane differs depending on the gas. Moisture has the fastest permeation rate in almost all gas separation membranes. Therefore, not only when removing moisture from the gas (dehumidification), but also when separating two or more mixed gases other than moisture with a membrane, if the mixed gas to be supplied contains moisture At the same time as the gas component that easily permeates the membrane, moisture also permeates the membrane, so that the space on the permeate side of the gas separation membrane module is relatively humid. For example, when enriched oxygen or enriched nitrogen is produced from air, moisture and oxygen are gas components that easily pass through the membrane, and nitrogen is a gas component that hardly penetrates the membrane. Therefore, enriched oxygen containing concentrated moisture is obtained on the permeate side of the membrane, and dry nitrogen is obtained on the non-permeate side of the membrane. Nitrogen is difficult to permeate the membrane, but the permeation rate is relatively slow and does not permeate at all, but permeates gradually.
[0005]
When the mixed gas supplied to the gas separation membrane module contains moisture, there is always concentrated moisture in the permeate side space in the gas separation membrane module (in other words, the dew point is raised). . When the operation is stopped in this state, the concentrated water remaining in the permeation side space in the gas separation membrane module is adsorbed on the membrane surface or condensed due to a temperature change or the like. As a result, when the operation of the gas separation membrane module is resumed, the membrane performance of the gas separation membrane module temporarily decreases due to the moisture adsorption and condensation until there is no moisture adsorption or condensation. Even when the mixed gas supplied in advance is simply dehumidified, the concentration of moisture occurs in the gas separation membrane module as described above, and thus it is not always possible to prevent the deterioration of the membrane performance as described above.
[0006]
In a nitrogen enrichment apparatus, there is disclosed a method and apparatus for preventing a temporary performance degradation of a separation membrane module that occurs during an operation stop and shortening the time until the performance of the membrane is restored when the operation is restarted. This is disclosed in Japanese Patent No. 24442. This method is to block the outside air during the operation stop period and eliminate the influence of contaminants and moisture in the outside air. However, there is no mention of the influence of moisture remaining in the apparatus when the gas separation membrane apparatus is at rest.
[0007]
[Problems to be solved by the invention]
In the present invention, when the mixed gas to be supplied contains moisture, the moisture remaining in the apparatus during the pause of the gas separation membrane apparatus adsorbs or condenses on the surface of the separation membrane to temporarily deteriorate the membrane performance. A simple, small, economical and easy-to-operate gas separation membrane device having a function of purging residual moisture in the device when the operation of the gas separation membrane device is stopped. An object of the present invention is to provide a method for stopping operation of a gas separation membrane device.
[0008]
[Means for Solving the Problems]
The present invention comprises at least one gas separation membrane module and at least one non-permeable gas storage device connected to the non-permeable gas outlet of the gas separation membrane module,
The function of stopping the supply of the mixed gas to the gas separation membrane module and purging the moisture in the non-permeation side and permeation side spaces in the gas separation membrane module with the non-permeation gas stored in the storage device. The present invention relates to a gas separation membrane device configured as described above and a method for stopping operation of the gas separation membrane device.
And a plurality of gas separation membrane modules and at least one non-permeate gas storage device connected to the non-permeate gas outlet of the gas separation membrane module,
With the exception of at least one gas separation membrane module among the gas separation membrane modules, the supply of the mixed gas is stopped, and the gas separation membrane module (A) that has continued to supply the mixed gas is discharged from the non-permeate gas discharge port. A non-permeate gas is supplied to a non-permeate side space in the gas separation membrane module (B) from which the supply of the mixed gas is stopped, and the non-permeate side and the permeate side in the gas separation membrane module (B) by the non-permeate gas The ability to purge the water in the space,
The supply of the mixed gas to the gas separation membrane module (A) that has continued to supply the mixed gas is stopped, and the non-permeate side in the gas separation membrane module (A) and the non-permeable gas stored in the storage device The present invention relates to the gas separation membrane device and a method for stopping the operation of the gas separation membrane device, characterized in that the gas separation membrane device has a function of purging moisture in a permeation side space.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
The selectively permeable gas separation membrane used in the gas separation membrane device of the present invention may be a flat membrane or the like. However, a hollow fiber membrane having a small thickness and a small diameter is separated because the device can be miniaturized and has a high membrane area. It is preferable because it is efficient and economical. Further, the gas separation membrane may be homogeneous, may be non-uniform such as a composite membrane or an asymmetric membrane, and may be microporous or nonporous. A hollow fiber membrane having a thickness of 10 to 500 μm and an outer diameter of 50 to 2000 μm can be preferably exemplified. Furthermore, the gas separation membrane of the present invention is made of a polymer material such as polyimide, polyetherimide, polyamide, polyamideimide, polysulfone, polycarbonate, silicone resin, cellulosic polymer, a material obtained by carbonizing or partially carbonizing the polymer material, zeolite, etc. A gas separation membrane formed of a ceramic material or the like can be preferably exemplified. In particular, an asymmetric polyimide gas separation membrane is preferable because it has not only high gas separation performance but also excellent properties such as heat resistance, durability, and solvent resistance.
[0010]
The gas separation membrane apparatus of the present invention includes one or a plurality of gas separation membrane modules. The gas separation membrane module usually consolidates many hollow fiber membranes (for example, hundreds to hundreds of thousands) into a hollow fiber bundle, and at least one end of the hollow fiber bundle is made of epoxy resin. A hollow fiber separation membrane element is formed by fixing the hollow fiber membrane so that the hollow fiber membrane is in an open state at the end portion with such a curable resin or a hot melt type thermoplastic resin, and further, one or a plurality of the hollow The yarn element is mounted in a container having at least a mixed gas supply port, a permeate gas discharge port, and a non-permeate gas discharge port so that a space leading to the inside of the hollow fiber is separated from a space leading to the outside of the hollow fiber. Configured. The container is made of a composite material such as a metal material such as stainless steel, a plastic material, or a fiber reinforced plastic material.
[0011]
The form of the gas separation membrane module used in the gas separation membrane device of the present invention is not particularly limited and may be a commonly used one. The arrangement of the hollow fiber bundles may be parallel, crossed, woven or spiral. Moreover, the hollow fiber bundle may be provided with a core tube at a substantially central portion, and a film may be wound around the outer peripheral portion of the hollow fiber bundle. Furthermore, the form of the hollow fiber bundle may be a columnar shape, a flat plate shape, a prismatic shape, or the like, and may be accommodated in the container as it is, bent into a U shape, or wound in a spiral shape.
[0012]
The gas separation membrane module of the present invention may be a hollow feed type or a shell feed type, and may be a type using a carrier gas or a type not using a carrier gas. In the type using carrier gas, a carrier gas introduction port is arranged in a container, or a carrier gas introduction pipe is arranged as a core pipe of a hollow fiber bundle.
[0013]
The gas separation membrane module of the present invention will be further described with reference to schematic diagrams. This schematic diagram is simplified for the sake of explanation. The gas separation membrane module of the present invention is not limited by this figure. The arrows in the figure indicate the direction of gas flow during normal operation.
FIG. 1 shows a schematic longitudinal sectional view of an example of a hollow feed type gas separation membrane module. The gas mixture is supplied from the mixed gas supply port 1 into the container 2 of the module. The supplied mixed gas flows through the space inside the hollow fiber membrane 6 in contact with the membrane surface and is discharged from the non-permeate gas discharge port 3. While the mixed gas flows through the space inside the hollow fiber membrane 6, gas components that easily pass through the membrane out of the mixed gas permeate to the outside of the hollow fiber membrane 6 and flow through the space outside the hollow fiber membrane 6 to permeate. It is discharged from the gas outlet 4. The space on the non-permeation side consisting of the inside of the hollow fiber membrane 6 and the non-permeate gas discharge port 3 from the mixed gas supply port 1 and the space on the permeation side consisting of the outer side of the hollow fiber membrane 6 and the permeate gas discharge port 4 are: It is isolated by the tube sheet 5.
[0014]
FIG. 2 shows a schematic longitudinal sectional view of an example of a shell feed type gas separation membrane module. In this case, the mixed gas supply port 1 and the non-permeate gas discharge port 3 are provided so as to communicate with the space outside the hollow fiber membrane 6, and in the space outside the tube plate 5 where the hollow fiber membrane 6 is open. A permeate gas outlet 4 is provided therethrough. The supplied mixed gas flows through the space outside the hollow fiber membrane 6 in contact with the membrane surface, and is discharged from the non-permeate gas discharge port 3. While the mixed gas flows through the space outside the hollow fiber membrane 6, gas components that easily pass through the membrane out of the mixed gas permeate through the inside of the hollow fiber membrane 6 and flow through the space inside the hollow fiber membrane 6 to permeate. It is discharged from the gas outlet 4. The space on the non-permeate side consisting of the mixed gas supply port 1 from the outside of the hollow fiber membrane 6 and the non-permeate gas discharge port 3 and the space on the permeate side consisting of the inner side of the hollow fiber membrane 6 and the permeate gas discharge port 4 are It is isolated by the tube sheet 5.
[0015]
The gas separation membrane device of the present invention has a non-permeate gas storage device connected to the non-permeate gas outlet of the gas separation membrane module. The non-permeating gas storage device may have any shape or form as long as it can store a sufficient amount of gas to purge the moisture in the space in the gas separation membrane module. A normal metal gas tank is preferably used. Further, the non-permeate gas storage device may be connected in series in the middle of a conduit that leads (or discharges out of the module) from the non-permeate gas discharge port of the gas separation membrane module to, for example, a device that uses gas. Alternatively, another conduit may be branched from the conduit and connected.
[0016]
Next, the function of purging moisture in the gas separation membrane module, which constitutes the characteristics of the gas separation membrane device of the present invention, and the method for stopping the operation of the gas separation membrane device will be described with reference to FIGS. FIGS. 3 and 4 are examples of one gas separation membrane module and one non-permeate gas storage device, and FIG. 5 is an example composed of three gas separation membrane modules and one non-permeate gas storage device. Is shown. The arrows in the figure indicate the direction of gas flow during normal operation. Moreover, these explanatory drawings show only the gas separation membrane module and the non-permeate gas storage device related to the features of the present invention, and other components are not shown. The present invention is not limited to these explanatory diagrams.
[0017]
3 and 4, during operation of the gas separation membrane module 12, the mixed gas is supplied from the valve 8, and the non-permeate gas is discharged through the valve 10 and the valve 11. Non-permeate gas is stored in the non-permeate gas storage device (tank) 7 during operation. The stored non-permeating gas is dried by allowing moisture to permeate to the permeation side while flowing through the gas separation membrane module 12, and the pressure of the supplied mixed gas (higher pressure than the permeation side). Holding.
When the operation is stopped, the valves 8 and 11 for supplying the mixed gas are first stopped. If the valve 11 is a check valve, it may be left as it is. Then, the space from the valve 8 to the non-permeate side of the gas separation membrane module 12, the inside of the non-permeate gas storage device (tank) 7 and the valve 11 is isolated as one space and has a higher pressure than the permeate side of the membrane. Remains. A small amount of unpermeated moisture remains in the mixed gas immediately after being supplied from the valve 8 to the gas separation membrane module, but most of the gas is already dried by the gas separation membrane module 12. On the other hand, in the space on the permeate side of the gas separation membrane module 12, gas components and moisture that easily permeate the membrane are present in a relatively high concentration. Further, the space on the permeate side is at a lower pressure than the non-permeate side, and communicates outside the gas separation membrane module by the valve 9. For this reason, a small amount of moisture remaining in the isolated space on the non-permeate side naturally passes through the membrane, but further, components that are difficult to permeate the membrane (which can gradually permeate) The permeated side high-concentration moisture is pushed out of the gas separation membrane module through the valve 9. This function continues while the non-transmission side space is at a higher pressure than the transmission side. In this way, moisture in the non-permeate side and permeate side spaces of the gas separation membrane module 12 is purged. After sufficient purge has been performed, the valve 9 and valve 10 can be closed if necessary.
[0018]
In FIG. 5, during operation of the gas separation membrane modules 12, 13, and 14, a gas mixture is supplied from the valves 16 and 17 to the gas separation membrane module. Valves 18, 19, 20, 21, 23, and 24 are open, and valve 22 is closed, and non-permeate gas flows through the non-permeate side of each gas separation membrane module, and non-permeate gas storage device (tank) 15 and It is discharged via the valve 24. Non-permeate gas is stored in the non-permeate gas storage device (tank) 15 during operation. The stored non-permeating gas is dried while the moisture permeates to the permeation side while flowing through the gas separation membrane modules 12 to 14, and the pressure of the supplied mixed gas (compared to the permeation side). High pressure).
When the operation is stopped, first, the valve 16 for supplying the mixed gas, the valve 21, the valve 23, and the valve 24 are closed, and the valve 22 is opened. If the valve 24 is a check valve, it may be left as it is. Then, the supply of the mixed gas to the gas separation membrane modules 12 and 13 is stopped, and the supply of the mixed gas to the gas separation membrane module 14 is continued. The non-permeated gas discharged from the gas separation membrane module 14 in which the supply of the mixed gas is continued is supplied through the valve 22 to the non-permeate side of the gas separation membrane module where the supply of the mixed gas is stopped. The supplied non-permeating gas has already been dried by passing through the membrane when passing through the gas separation membrane module 14. In the space on the non-permeate side of the gas separation membrane modules 12, 13, there is a mixed gas immediately after being supplied from the valve 16 to the gas separation membrane module, and a small amount of unpermeated moisture remains, but it is newly supplied. Most of the gas is dried by the non-permeating gas of the gas separation membrane module 14. On the other hand, in the space on the permeate side of the gas separation membrane modules 12 and 13, there are relatively high concentrations of gas components and moisture that easily permeate the membrane. The space on the permeate side is at a lower pressure than that on the non-permeate side, and is communicated to the outside of the gas separation membrane module by valves 18 and 19. For this reason, a small amount of moisture remaining on the non-permeating side of the gas separation membrane modules 12 and 13 naturally permeates the membrane, but further, a component that is difficult to permeate the membrane (which can gradually permeate) is caused by the pressure difference. Is gradually permeated, and high-concentration moisture on the permeate side is pushed out of the gas separation membrane module through valves 18 and 19. In this way, moisture in the spaces on the non-permeable side and the permeable side of the gas separation membrane modules 12 and 13 is purged. After sufficient purging has been performed, the valves 18, 19 can be closed if necessary.
[0019]
Next, the valve 17 is closed, the supply of the mixed gas to the gas separation membrane module 14 is stopped, the valve 22 is closed, and the valve 23 is opened. Then, the non-permeate side of the gas separation membrane module 14 from the valve 17 and the inside of the non-permeate gas storage device (tank) 15 and the valve 24 via the valve 23 are isolated as one space, and the gas separation membrane module 14 A high-pressure dried gas remains as compared with the permeate side of the gas. A small amount of unpermeated moisture remains in the mixed gas immediately after being supplied from the valve 17 to the gas separation membrane module 14, but most of the gas is already dried by the gas separation membrane module. On the other hand, in the space on the permeate side of the gas separation membrane module 14, gas components and moisture that easily permeate the membrane are present at relatively high concentrations. Further, the space on the permeate side is at a lower pressure than the non-permeate side, and is communicated to the outside of the gas separation membrane module 14 by the valve 20. For this reason, moisture remaining in the isolated space on the non-permeate side naturally passes through the membrane, but moreover, components that are difficult to permeate the membrane (which can gradually permeate) gradually permeate the membrane due to the pressure difference. Thus, high-concentration moisture on the permeate side is pushed out of the gas separation membrane module through the valve 20. This function continues while the non-transmission side space is at a higher pressure than the transmission side. In this way, moisture in the non-permeate side and permeate side spaces of the gas separation membrane module 14 is purged. After sufficient purging has been performed, the valves 20 and 23 can be closed as necessary.
[0020]
In the present invention, in the type in which the gas separation membrane module introduces the dried carrier gas to the permeate side, it is effective to flow the carrier gas even during the stop operation. Furthermore, in the type in which the gas separation membrane module circulates a part of the non-permeate gas as a carrier gas to the permeate side (through the introduction passage in the module), the dry non-permeate gas from the non-permeate gas storage device is removed during the stop operation. Since it automatically flows to the permeate side through the introduction passage, water can be purged more efficiently.
[0021]
In the gas separation membrane module, the supplied mixed gas must be at a higher pressure than the permeate side of the membrane. Normally, the mixed gas is supplied after being pressurized with a compressor or blower. Furthermore, the space on the permeate side of the gas separation membrane module may be decompressed by an ejector or the like. When the space on the permeate side is decompressed, it is preferable to continue the decompression during the pause operation.
[0022]
The gas separation membrane device of the present invention includes a gas separation membrane module and a non-permeate gas storage device connected to the non-permeate gas discharge port, and is used to pressurize and depressurize the device. Although it is provided with a conduit, a valve, etc., it may further comprise various units provided in a normal gas separation membrane device. Compressor and air blower for pressurizing the mixed gas, such as dust filter, oil filter, mist separator, scrubber, adsorber, etc. In order to remove excess moisture from the mixed gas in advance, such as devices such as concentration measurement monitors to adjust flow rate, pressure and purity, pressure monitors, pressure reducing valves, flow rate adjustment valves, etc. A preliminary dehumidifying device or the like, and a preheating device that preheats the supplied mixed gas may be provided.
[0023]
The gas separation membrane device and the operation stop method of the gas separation membrane device of the present invention can be preferably applied when moisture is contained in the supplied mixed gas. Applicable to dehumidification of air, production of enriched nitrogen and enriched oxygen from air, separation, recovery and purification of inorganic gas and organic gas, dehydration of organic vapor, etc. Can do. If the gas separation membrane apparatus and the operation stop method of the present invention are applied, the operation can be preferably restarted without temporary deterioration of the membrane performance after the operation of the gas separation membrane apparatus is stopped.
[0024]
Next, an embodiment of the gas separation membrane device of the present invention will be described with reference to schematic views. These drawings do not limit the present invention.
In FIG. 6, the mixed gas is supplied from the mixed gas intake port 25, pressurized by the compressor 27, preliminarily dehumidified by the freezing dehumidifier 28, adjusted to a predetermined pressure by the pressure reducing valve 32, and a predetermined temperature by the heat exchanger 36. After the temperature is adjusted, the gas separation membrane module 40 is supplied. The permeate gas is recovered through the flow rate control valve 43, and the non-permeate gas is recovered through the flow rate control valve 44 and the non-permeate gas storage device 45. Dust and impurity gas present in the supplied mixed gas, oil and oil mist mixed from the compressor, etc. may cause performance degradation for the gas separation membrane, so the dust filter 26, oil filter 30, air filter 31. The mist separator 33, the activated carbon adsorption device 34, the dust separator 35, and the like are removed. In addition, a thermometer 37, a pressure gauge 38, a gas concentration meter 41, and a flow meter 42 are provided to monitor pressure, temperature, gas concentration, flow rate, etc., and a valve 39 and flow rate are provided for gas flow switching and flow rate adjustment. Adjusting valves 43 and 44 are provided.
7 to 9 show typical examples of embodiments of a gas separation membrane device including three gas separation membrane modules, particularly a combined form of a plurality of gas separation membrane modules. In addition, although a unit such as a filter is illustrated in a simplified manner, another pre-processing unit or a monitor is added as necessary.
[0025]
【Example】
Next, the present invention will be further described with reference to examples. In addition, this invention is not limited to this Example.
(Example)
In the gas separation membrane apparatus including the configuration as shown in FIG. 3, a gas separation membrane for enriched nitrogen formed by bundling a large number of asymmetric aromatic polyimide hollow fiber separation membranes having a film thickness of 100 μm, an outer diameter of 500 μm, and a length of 450 mm The following operations were performed using the module.
The pressure of compressed air entering the nitrogen enrichment module was adjusted to 0.7 MPa (gauge pressure), a temperature of 25 ° C., and the flow rate of the nitrogen enriched gas was 35 NL / min, and the operation was performed for 8 hours. At this time, the oxygen concentration of the nitrogen-enriched gas was 4.97% by volume. After operation for 8 hours, according to the method of the present invention, the valves 8 and 11 were closed, the inside of the module was purged with nitrogen-enriched gas in the storage device (tank), and then the valve 9 was closed to stop the operation.
Operation resumed after a 15-hour pause. During the pause, the ambient temperature had dropped to at least 0 ° C. The nitrogen concentration immediately after resuming operation was 4.98% by volume, which was almost the same as at the end of operation.
(Comparative example)
In the gas separation membrane apparatus including the same configuration as in FIG. 3 except for the non-permeate gas storage device (tank), the operation was performed simultaneously with the above example. During the initial operation, almost the same operation as in the example was possible, but when the operation was resumed 15 hours after the operation stop, the oxygen concentration of the nitrogen-enriched gas was 5.20% by volume. It took 120 minutes or more to obtain a nitrogen-rich gas having the same oxygen concentration as in the first operation and to reach a steady operation.
FIG. 10 shows a graph of the measurement results of the example and the comparative example. According to the present invention, it can be seen that the time required to reach the steady operation when the operation is resumed is greatly shortened.
[0026]
【The invention's effect】
Since the present invention is as described above, the following effects can be obtained.
When the gas separation membrane device and the operation suspension method of the present invention are used, when the mixed gas to be supplied contains moisture, moisture remaining in the device during the suspension of the gas separation membrane device is adsorbed or condensed on the surface of the separation membrane. Therefore, the problem of temporarily lowering the membrane performance can be prevented from occurring, so that the gas separation membrane device can be restarted immediately after restarting the operation without lowering the membrane performance.
The gas separation membrane apparatus of the present invention is a simple, small, economical and easy-to-operate gas separation membrane apparatus having a function of purging residual moisture in the apparatus when it is stopped.
[Brief description of the drawings]
FIG. 1 is a schematic view of a longitudinal section showing an example of a hollow feed type gas separation membrane module. FIG. 2 is a schematic view of a longitudinal section showing an example of a shell feed type gas separation membrane module. FIG. 4 is an explanatory diagram of a function of purging moisture in the separation membrane module and a method for stopping the operation of the gas separation membrane apparatus. Explanatory diagram FIG. 5 is an explanatory view of a function of purging moisture in the gas separation membrane module of the present invention and a method of stopping the operation of the gas separation membrane device. FIG. 6 is a schematic diagram showing an embodiment of the gas separation membrane device of the present invention. 7 is a schematic view showing an embodiment of the gas separation membrane apparatus of the present invention. FIG. 8 is a schematic view showing an embodiment of the gas separation membrane apparatus of the present invention. FIG. 9 is an embodiment of the gas separation membrane apparatus of the present invention. Schematic diagram showing Fig. 10 [EXPLANATION OF SYMBOLS] shows the time course of the oxygen concentration of the resulting nitrogen-rich gas in the examples and comparative examples of the present invention
1: Mixed gas supply port 2: Container 3: Non-permeate gas discharge port 4: Permeate gas discharge port 5: Tube plate 6: Hollow fiber gas separation membrane 7: Non-permeate gas storage devices 8, 9, 10, 11: Valve 12 , 13, 14: Gas separation membrane module 15: Non-permeate gas storage device 16, 17, 18, 19, 20, 21, 22, 23, 24: Valve 25: Mixed gas intake 26: Dust filter 27: Compressor 28: Refrigeration and dehumidifier 29: Tank 30: Oil filter 31: Air filter 32: Pressure reducing valve 33: Mist separator 34: Activated carbon adsorption device 35: Dust separator 36: Heat exchanger 37: Thermometer 38: Pressure gauge 39: Valve 40: Gas Separation membrane module 41: Gas concentration meter 42: Flow meter 43, 44: Flow control valve 45: Non-permeate gas storage device (tank)

Claims (1)

Nitrogen enriched from air by a gas separation membrane device comprising a plurality of gas separation membrane modules and at least one non-permeate gas storage device connected to a non-permeate gas outlet of the gas separation membrane module In the manufacturing method,
First, the supply of the mixed gas is stopped except for at least one gas separation module among the gas separation membrane modules, and the non-permeate gas of the gas separation membrane module (A) that has continued to supply the mixed gas is used as the mixed gas. The gas is supplied to the non-permeate side space in the gas separation membrane module (B) where the supply is stopped, and the moisture in the non-permeate side and the permeate side space in the gas separation membrane module (B) is purged by the non-permeate gas. ,
Next, the gas supply to the gas separation membrane module (A) that has continued to supply the mixed gas is stopped, and the non-permeate gas stored in the storage device is transferred to the non-permeate side space in the gas separation membrane module (A). Until the non-permeate gas purges the moisture in the non-permeate side and the permeate side space in the gas separation membrane module (A) until a nitrogen-enriched air having a predetermined concentration is obtained when the operation is resumed. A method for stopping operation of a gas separation membrane device, characterized in that time is shortened.

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