JP5830989B2 - Mixed gas separator - Google Patents

Description

  The present invention provides a gas separation apparatus having a plurality of gas separation membrane modules, and can constitute two gas separation membrane units connected in series by a simple method, and the gas separation membranes included in each gas separation membrane unit The present invention relates to a gas separation device capable of adjusting the number of modules.

  As a mixed gas separation method, there is a membrane separation method using a difference in gas permeation rate with respect to a polymer membrane. For example, a method using a gas separation membrane module having a gas separation membrane is known. The gas separation membrane module comprises a gas separation membrane having gas permselectivity in a container having a gas supply port, a permeate gas discharge port, and a non-permeate gas discharge port. It is installed so that the space is isolated. FIG. 1 shows a gas when a gas separation membrane module separates a mixed gas containing at least a gas with high permeability to a gas separation membrane (high permeability gas) and a gas with low permeability to a gas separation membrane (low permeability gas). It is the schematic diagram which showed the flow of. FIG. 1A is a schematic view of a bore feed type, and FIG. 1B is a schematic view of a shell feed type gas separation membrane module (details will be described later). While the mixed gas supplied from the gas supply port 11 of the gas separation membrane module flows in contact with the hollow fiber membrane 14 in the gas separation membrane module, a gas containing a high permeation gas (permeation gas) is hollow fiber membrane 14. Is separated into the remaining gas (non-permeate gas) that has not permeated and contains less highly permeable gas. The permeated gas is discharged from the permeated gas outlet 12, and the non-permeated gas is discharged from the non-permeated gas outlet 13. Only one or both of the non-permeate gas and the permeate gas discharged from the gas separation membrane module are recovered depending on the application.

  And in order to collect | recover gas with high concentration and a high recovery rate, the method of using the apparatus provided with the separation membrane module in multiple steps is known (patent documents 1, 2, 3, etc.). In this method, for example, a mixed gas as a raw material is supplied to the gas supply port of the first-stage separation membrane module, and the discharged permeated gas or non-permeated gas is supplied to the second-stage separation membrane module to obtain a high concentration. This is a method for recovering a high permeation gas or a low permeation gas. Further, as a method for improving the throughput, there is also known a method in which a plurality of separation membrane modules are connected in parallel, and the units are connected in series in multiple stages (Patent Document 2, etc.).

  FIG. 2 is an example of a conventional gas separation device that collects non-permeate gas in a two-stage unit. The first stage includes a mixed gas supply path (211), a permeate gas discharge path (212), a non-permeate gas recovery path (213), three flow paths, and three modules (221a, 221b, 221c), The flow paths 211, 212, and 213 are connected to the modules 221a, 221b, and 221c through branch paths, respectively. The second stage includes a flow path (215) for supplying the non-permeate gas from the first stage, three flow paths of a permeate gas discharge path (216) and a non-permeate gas recovery path (217), and three modules ( 221d, 221e, 221f), and the flow paths 215, 216, 217 are connected to the modules 221d, 221e, 221f via branch paths, respectively. Furthermore, the flow path 213 and the flow path 215 are connected via the flow path 214.

  In the apparatus of FIG. 2, first, the mixed gas supplied from the supply port 231 is supplied from the first stage flow path 211 to the gas separation membrane modules 221a, 221b, and 221c through the branch path, Separated into permeate gas and permeate gas. The non-permeate gas discharged from the discharge port of each module is recovered in the non-permeate gas recovery path 213 through the branch path. On the other hand, the permeate gas is discharged from the permeate gas discharge path 212.

  The recovered first-stage non-permeating gas is supplied to the gas separation membrane modules 221d, 221e, and 221f from the second-stage gas supply path 215 through the flow path 214. Then, the non-permeate gas separated and discharged in these gas separation membrane modules is recovered from the non-permeate gas recovery path 217. Thereby, a low permeation gas separated and concentrated in two stages is obtained. On the other hand, the permeated gas discharged from the second-stage gas separation membrane module is supplied to the flow path 216 and then recycled to the raw material supply port through the flow path 218 in order to increase the recovery rate from the raw material. .

  In the separation of mixed gases such as biogas, there may be cases where significant changes in conditions for separation and concentration using separation membrane modules are required depending on the composition and amount of raw materials and the quality and amount of product gas. is there. However, in the conventional method shown in FIG. 2, since the number of separation membrane modules is fixed, when changing the conditions, it can only be dealt with by changing the supply pressure, temperature, etc. of the raw material, and the conditions can be changed significantly. Could not follow. Therefore, further improvement of the gas separation apparatus has been demanded so as to flexibly cope with a large change in conditions.

JP 2005-161187 A Japanese Unexamined Patent Publication No. 7-748 JP 2007-254572 A

  An object of the present invention is to provide a gas separation device that can solve the above problems and can easily change the condition setting.

  The present invention relates to the following matters.

1. Three or more gas separation membrane modules;
A supply gas flow path (flow path 1) connected to all gas separation membrane modules;
A non-permeate gas channel (channel 3) connected to all gas separation membrane modules;
A valve,
Comprising:
The valve is provided between the branch points connected to the gas separation membrane modules on the flow path 1 and the flow path 3,
By closing the valve on the flow path 1 and the valve on the flow path 3 between the same modules, the first gas separation membrane unit to which the source gas is supplied and the second gas separation membrane unit connected in series therewith are provided. Can be configured,
By selecting opening and closing of each valve, the number of gas separation membrane modules constituting the first gas separation membrane unit and the second gas separation membrane unit can be adjusted;
Furthermore, a gas separation apparatus comprising a gas flow path (flow path 4) for supplying the non-permeated gas recovered from the first gas separation membrane unit to the second gas separation membrane unit.

2. Furthermore, a flow path for the permeated gas (flow path 2) connected to all the gas separation membrane modules and a valve provided between the branch points connected to the gas separation membrane modules on the flow path 2 are provided. 2. The gas separation device according to 1 above.

3. 3. The gas separation device according to 2 above, further comprising a gas flow path (flow path 5) for supplying the permeated gas discharged from the second gas separation membrane unit to the first gas separation membrane unit. .

4). 3. The gas separation device according to 1 or 2 above, further comprising a valve on the flow path 4.

5. 4. The gas separation device according to 3 above, further comprising a valve on the flow path 4 and the flow path 5.

6). Furthermore, the gas separation apparatus of any one of said 1-5 provided with a compressor on the said flow path 4.

7). Furthermore, the flow path 3 has a branched flow path 6, and a part of the non-permeated gas recovered from the second gas separation membrane unit by the flow path 6 is converted into the first gas separation membrane unit and / or 7. The gas separation device according to any one of 1 to 6, which can be supplied as a purge gas into the second gas separation membrane unit.

8). 8. A method for separating a mixed gas, wherein the gas separation device according to any one of 1 to 7 is used in a state in which one or more valves on the flow path 1 and the flow path 3 are closed between the same modules.

9. The gas separation device according to any one of 2 to 7 above, wherein one or more valves on the flow channel 1, the flow channel 2, and the flow channel 3 are used in a closed state between the same modules. Gas separation method.

10. 5. A mixed gas in which the gas separation device according to 4 is used with all the valves between the gas separation membrane modules on the flow path 1 and the flow path 3 opened and the valves on the flow path 4 closed. Single-stage separation method.

11. The gas separation device according to 5 is used in a state where all the valves between the gas separation membrane modules on the flow paths 1 to 3 are opened and the valves on the flow paths 4 and 5 are closed. , Single-stage separation method of mixed gas.

12 Three or more gas separation membrane modules;
A supply gas flow path (flow path 1) connected to all gas separation membrane modules;
A permeating gas channel (channel 2) connected to all gas separation membrane modules;
A valve,
Comprising:
The valve is provided between the branch points connected to the gas separation membrane modules on the flow channel 1 and the flow channel 2,
By closing the valve on the flow path 1 and the valve on the flow path 2 between the same modules, the gas separation device can constitute a first gas separation membrane unit and a second gas separation membrane unit, and
By selecting opening and closing of each valve, the number of gas separation membrane modules constituting the first gas separation membrane unit and the second gas separation membrane unit can be adjusted;
Furthermore, a gas separation apparatus comprising a gas flow path (flow path 7) for supplying the permeated gas recovered from the first gas separation membrane unit to the second gas separation membrane unit.

13. Furthermore, a valve provided between a non-permeate gas flow channel (flow channel 3) connected to all gas separation membrane modules and a branch point connected to the gas separation membrane module on the flow channel 3 is provided. 13. The gas separation apparatus as described in 12 above.

14 Furthermore, the gas separation apparatus of said 13 provided with the gas flow path (flow path 8) for supplying the non-permeating gas discharged | emitted from the 2nd gas separation membrane unit to a 1st gas separation membrane unit.

15. 15. A method for separating a mixed gas, wherein the gas separation device according to any one of 12 to 14 is used with one or more valves on the flow channel 1 and the flow channel 2 being closed between the same modules.

16. 15. A method for separating a mixed gas, wherein the gas separation device according to 13 or 14 is used in a state where one or more valves on the flow channel 1, the flow channel 2, and the flow channel 3 are closed between the same modules.

  The present invention provides a gas separation apparatus having a plurality of gas separation membrane modules, and can constitute two gas separation membrane units connected in series by a simple method, and the gas separation membranes included in each gas separation membrane unit A device capable of adjusting the number of modules is provided. Thereby, the condition setting which performs gas separation can be changed greatly according to the composition of raw material gas and the demand for product gas. In addition, the gas separation apparatus of the present invention can be easily used when performing gas separation in a single stage or when supplying purge gas, and allows more flexible condition setting.

An example of a structure of a bore feed type gas separation membrane module (A) and a shell feed type gas separation membrane module (B) is shown. An example of the structure of the conventional gas separation apparatus is shown. An example of the gas separation apparatus of this invention is shown. An example of the gas separation apparatus of this invention is shown. An example of the gas separation apparatus of this invention is shown. An example of the gas separation apparatus of this invention is shown. An example of the gas separation apparatus of this invention is shown. An example of the gas separation apparatus of this invention is shown. An example of the gas separation apparatus of this invention is shown. An example of the gas separation apparatus of this invention is shown. An example of the gas separation apparatus of this invention is shown. An example of the gas separation apparatus of this invention is shown. The schematic of the gas separation apparatus of an Example is shown.

<Structure of gas separator>
Hereinafter, the gas separation apparatus of the present invention will be described in detail. The present invention relates to both an apparatus for separating and concentrating a low permeable gas having low permeability to a gas separation membrane and an apparatus for separating and concentrating a highly permeable gas having high permeability to a gas separation membrane. Although FIGS. 3-12 shows the specific example of a structure of the gas separation apparatus of this invention, this invention is not limited to these. 3 to 10 are examples of aspects in which the non-permeate gas side is recovered in two stages, and FIGS. 11 and 12 are examples of aspects in which the permeate gas side is recovered in two stages.

  The gas separation membrane module in the following embodiment will be described by taking a separation membrane module constituted by a hollow fiber membrane as an example. As gas separation membrane modules constituted by hollow fiber membranes, so-called bore feed type and shell feed type are known. For example, in a bore feed type gas separation membrane module, as shown in FIG. 1 (A), a large number of hollow fiber membranes (for example, several hundred to several hundred thousand) are converged to form a hollow fiber bundle. The hollow fiber bundle is accommodated in a container (15) having at least a gas supply port (11), a permeate gas discharge port (12), and a non-permeate gas discharge port (13), and both ends of the hollow fiber bundle. Are fixed to the container 15 with a curable resin such as an epoxy resin or a thermoplastic resin such as a polyamide resin so that the hollow fiber membrane is open at the end portion to form the tube plates 16a and 16b. A space (gas non-permeate side) through which gas is supplied from the supply port (11) and passes through the inside of the hollow fiber membrane (14) to the non-permeate gas discharge port (13), and from the outside of the hollow fiber membrane (14) Space leading to the permeate gas outlet (12) (gas permeation ) And is configured to isolate. A container is manufactured with composite materials, such as metal materials, such as stainless steel, a plastic material, and a fiber reinforced plastic material, for example. In the shell feed type gas separation membrane module, for example, as shown in FIG. 1 (B), a tube plate is formed at one end of the hollow fiber bundle, and gas is supplied from the gas supply port (11). The gas non-permeate side space leading to the non-permeate gas outlet (13) is outside the hollow fiber membrane (14), and the gas permeate side space leading to the permeate side exhaust port (12) is the hollow fiber membrane (14 ) Is configured inside. In the following description, the gas separation membrane module may be simply referred to as a module.

<Embodiment 1>
The gas separation device of FIG. 3 has six gas separation membrane modules (341a to 341f) arranged in one direction from the upstream to the downstream with the source gas supply port side as an upstream, and a supply gas flow channel (flow channel 1) ( 311), a permeate gas channel (channel 2) (312), and a non-permeate gas channel (channel 3) (313). The channel 1 (311), the channel 2 (312), and the channel 3 (313) each have a branch path branched from a branch point, and each flow path is connected to all six modules via the branch path. Connected. In the following description, with respect to the arrangement of the modules, the direction closer to the raw material supply port is the upstream side, and the far side is the downstream side. That is, the module 341a is the most upstream module, and the module 341f is the most downstream module.

  In each flow path of the gas separation device in FIG. 3, a valve is further provided between the branch points. That is, five valves (321a to 321e) are provided on the flow path 1, five valves (322a to 322e) are provided on the flow path 2, and five valves (323a to 323e) are provided on the flow path 3. In FIGS. 3 to 12, a black valve indicates that the valve is closed, and a white valve indicates that the valve is open.

  Here, FIG. 3 illustrates a case where three valves (black 321b, 322b, 323b) between the module 341b and the module 341c are closed. Thereby, the flow paths 1-3 are each divided | segmented between the module 341b and the module 341c. The gas separation device includes a first gas separation membrane unit (301) including two gas separation membrane modules (341a and 341b) and four gas separation membrane modules (341c to 341f). A second gas separation membrane unit (302) is configured. When opening and closing the valves, the valves on each flow path are closed between the same modules so that the permeation gas or non-permeation gas between the units is not mixed (for example, in FIG. 3, 321b, 322b, and 323b are closed). Close the valve containing the same alphabet on each flow path). In the following description, the gas separation membrane unit may be simply referred to as a unit.

  Further, the gas separation device of FIG. 3 includes a flow path 4 (314) and a flow path 5 (315). The flow path 4 (314) connects the branch point (381) on the flow path 3 (313) and the branch point (382) on the flow path 1 (311). The branch point (381) is a branch point on the flow path 3 that branches to the branch path (333a) to the most upstream module 341a, and the branch point (382) is a branch path (331f to the most downstream module 341f). ) Is a branching point on the flow path 1 that branches off. The flow path 5 (315) connects the branch point (383) on the flow path 2 (312) and the point (384) on the flow path 1 (311). The branch point (383) is a branch point on the flow path 2 that branches to the branch path (332f) to the most downstream module 341f, and the point (384) is a raw material supply port (311) on the flow path 1 (311). 351) is located downstream from the branch point (371) branching to the branch path (331a) to the most upstream module 341a.

  The mixed gas as the raw material is first pressurized by the compressor 361 from the supply port 351 and supplied to the flow path 1 (311), and the inside of the hollow fiber membrane in the module (341a and 341b) in the first unit. Pass through. In the module, the mixed gas is separated into a gas that has permeated through the hollow fiber membrane (permeate gas) and a gas that has passed through the hollow fiber membrane without passing through it (non-permeate gas). 313). On the other hand, the permeate gas is discharged or collected from the discharge port 352 through the flow path 2 (312).

  Here, the flow of gas passing through the module 341a will be described. The mixed gas of the raw material supplied from the supply port 351 passes through the branch path from the branch point (371) on the flow path 1 (311) and from the supply port (372) communicating with the inside of the hollow fiber membrane of the module 341a. Supplied in the module. The non-permeating gas that has passed through the hollow fiber membrane in the module 341a as it is is discharged from the discharge port (374) of the module 341a, and is supplied into the flow path 3 (313) through the branch path. On the other hand, the permeated gas is discharged from the discharge port (373) of the module 341a, supplied to the flow path 2 (312) through the branch path, and discharged from the discharge port 352. This permeate gas may be recovered as required. Further, the gas flow in the other module 341b constituting the first unit is the same as that of the module 341a.

  The non-permeating gas supplied from the first unit to the flow path 3 (313) passes through the flow path 4 (314) and is supplied to the flow path 1 (311) in the second unit. It is supplied from the road to the modules (341c to 341f) in the second unit. Then, the hollow fiber membranes in the modules (341c to 341f) separate the non-permeate gas and the permeate gas, and the non-permeate gas is supplied into the flow path 3 (313) and recovered from the recovery port (354). . On the other hand, the permeating gas is supplied into the flow path 2 (312).

  Here, the flow of gas passing through the module 341f will be described. The non-permeating gas recovered from the first unit is supplied to the flow path 1 through the flow path 4 (314), passes through the branch path from the flow path 1, and enters the module 341f from the supply port (375) of the module 341f. To be supplied. The non-permeate gas that has passed through the hollow fiber membrane in the module 341f as it is is discharged from the discharge port (377) of the module 341f, supplied to the flow path 3 through the branch path, and recovered from the recovery port (354). . On the other hand, the permeated gas from the module 341f is discharged from the discharge port 376 and supplied to the flow path 2 (312) through the branch path. The gas flow in the other modules 341c to 341e constituting the second unit is the same as that of the module 341f.

  The permeated gas discharged from the modules 341c to 341f is supplied into the flow path 2 (312) through the branch path as described above, and subsequently, the flow path 5 (315) connected to the flow path 2 (312). And is supplied to the first unit from the point (384) on the flow path 1 (311) (that is, recycled). By recycling the permeated gas in this way, the recovery rate of the gas from the raw material can be increased. For example, when separating biogas containing methane gas and carbon dioxide as main components, in order to increase the recovery rate of methane gas, which is a low permeate gas recovered as a non-permeate gas, the permeate gas discharged from the second unit is again used. It is preferable to supply (recycle) the first unit.

  As described above, in the gas separation measure of the present invention, the first gas separation membrane unit and the second gas separation membrane unit are connected in series, so that the mixed gas of the raw material undergoes a two-stage gas separation step, A high concentration low permeation gas can be recovered. And in this invention, since it has a valve | bulb between each branch point of the flow paths 1, 2, and 3, it selects opening and closing of a valve by setting conditions, and comprises a 1st unit and a 2nd unit It is possible to adjust the number of each module. 4 and 5 show an example in which the number of modules constituting the first unit and the second unit is adjusted by changing the selection of the valves.

  FIG. 4 shows a case where the first unit and the second unit include three modules by changing the closing valve to 321c, 322c, and 323c in the same gas separation apparatus as FIG. Thus, according to the present invention, it is possible to easily adjust the number of modules included in each unit only by changing the valve to be opened and closed.

  FIG. 5 shows that in the gas separation apparatus similar to FIG. 3, the gas is not supplied to the module 341c by closing the six valves 321b, 322b, 323b, 321c, 322c and 323c, and the first unit is A case where two modules (341a and 341b) are included and the second unit includes three modules (341d, 341e, 341f) is shown. As described above, the gas separation device of the present invention can reduce the number of modules used in accordance with the product demand, and can be adapted to a wider range of conditions.

<Embodiment 2>
FIG. 6 shows a gas separation device that does not have the flow path 5 among the components of the gas separation device of FIG. In this case, it is the same as in Embodiment 1 except that the permeated gas discharged from the second unit is not recycled and is discharged from the discharge port 353. As in the first embodiment, the number of modules constituting the first unit and the second unit can be easily adjusted only by selecting whether to open or close the valve. In the apparatus of FIG. 6, when any permeate gas from the first unit and the second unit is discharged without being recovered, or when the permeate gas from the first unit and the second unit is recovered together, Since the path 2 (312) does not have to be divided, the valves (322a, 322b, 322c, 322d, 322e) on the flow path 2 (312) need not be closed, and these valves need not be provided. Good. If all the permeate gas is discharged without being collected, the flow path 2 (312) may not be provided.

<Embodiment 3>
FIG. 7 shows an apparatus in which a compressor (362) is provided on the flow path 4 in addition to the components of the gas separation apparatus of FIG. Thereby, the non-permeating gas recovered from the first unit can be supplied to the second unit while being pressurized by the compressor. Also in the third embodiment, as in the first embodiment, the number of modules constituting each unit can be easily adjusted by selecting the opening and closing of the valve. Moreover, the structure which does not have the flow path 5 like Embodiment 2 may be sufficient.

<Embodiment 4>
FIG. 8 is a device that can perform gas separation in a single stage, and is provided with two valves (324, 325) in addition to the components of the gas separation device of FIG. By closing the valves 324 and 325, gas passes through the flow paths 1, 2, and 3, but gas does not pass through the flow paths 4 and 5. The valve 324 may be provided on the flow path 4 as long as the connection between the flow path 1 and the flow path 4 can be cut off. The valve 325 is provided on the flow path 5 as long as the connection between the flow path 2 and the flow path 5 can be cut off. When the valves 324 and 325 are closed and the other valves are opened, the two units are not configured, and a single-stage gas separation device using all modules can be obtained. As described above, the gas separation device of the present invention can be used in a single stage in addition to the use of the two-stage configuration described in the first embodiment only by selecting whether to open or close the valve.

<Embodiment 5>
9 and 10 show a gas separation apparatus that can use a part of the non-permeated gas (product gas) recovered from the second unit as a purge gas. 9 and 10, in addition to the components of the apparatus of FIG. 3, a flow path 6 (a second unit side of the flow path 3 (313) (a non-permeate gas recovery port side of the second unit) is branched. 316). The flow path 6 is connected to a purge gas supply port communicating with the permeation side (outside) of the hollow fiber membrane in each module via a branch path. Valves are provided between the branch points to the modules on the flow path 6 (326a to 326e), and two valves 327 and 328 are further provided.

  FIG. 9 shows a state in which a part of the non-permeated gas recovered from the second unit is used as the purge gas for the second unit. Among the valves 326a to 326e, the valve between the same modules as the valves on the flow paths 1 to 3 (black 326b) is closed, and the flow path 6 is divided between the modules 341b and 341c. Further, the valve 327 is opened and the valve 328 is closed. Thereby, a part of the non-permeating gas recovered from the second unit is supplied as a purge gas to the permeation side of the gas separation membrane in the four modules (341c to 341f) constituting the second unit.

  On the other hand, in the use state shown in FIG. 10, the opening and closing of the valves 327 and 238 is opposite to the case of FIG. 9, and the valve 327 is closed and the valve 328 is opened. Thereby, a part of the non-permeating gas recovered from the second unit is supplied as a purge gas to the permeation side of the gas separation membrane in the two modules (341a and 341b) constituting the first unit.

  Also in the apparatus of FIG. 9 and FIG. 10, the number of modules constituting each unit can be easily adjusted by selecting the opening and closing of the valve as in the other embodiments.

<Embodiment 6>
FIG. 11 shows an apparatus that separates and concentrates permeate gas in two stages. This apparatus can be used for the purpose of obtaining a high permeation gas as a product, but can also be used for the purpose of increasing the recovery rate of the low permeation gas when obtaining a low permeation gas as a product. The apparatus of FIG. 11 includes six gas separation membrane modules (341a to 341f), a supply gas channel (channel 1) (311), a permeate gas channel (channel 2) (312), and a non-permeate gas. The flow path (flow path 3) (313) and valve | bulb are provided similarly to the apparatus of FIG. Furthermore, the apparatus of FIG. 11 includes a flow path 7 (317) instead of the flow path 4 in the apparatus of FIG. The flow path 7 connects the branch point to the most upstream module 341a on the flow path 2 (312) and the branch point to the most downstream module 341f on the flow path 1 (311). A compressor (363) is preferably provided on the flow path 7.

  The permeated gas discharged from the modules (341a, 341b) in the first unit is supplied to the flow path 2 (312), and then passes through the flow path 7 (317) to the modules (341c to 341f) in the second unit. ) In the hollow fiber membrane. The permeated gas discharged from the module in the second unit is recovered from the discharge port (353) of the flow path 2. As a result, a high-concentration, high-permeation gas concentrated in two stages is obtained.

  As for the non-permeate gas, the non-permeate gas discharged from the first unit and the non-permeate gas discharged from the second unit may be recovered separately from the exhaust ports 355 and 354, respectively, or only one of them may be recovered. May be. Further, when collecting the non-permeating gas from the first unit and the second unit together, or when discharging the non-permeating gas without collecting the non-permeating gas, the valves (323a to 323e) on the flow path 3 are set. It does not have to be closed and these valves need not be provided. If all the non-permeating gas is discharged without being collected, the flow path 3 (313) may not be provided.

  In the gas separation device of FIG. 11 as well, as in the first embodiment, the number of modules constituting the first unit and the second unit can be easily adjusted simply by selecting whether to open or close the valve. Further, similarly to Embodiments 4 and 5, by providing a valve, it can be used in a single stage or a purge gas can be supplied.

<Embodiment 7>
FIG. 12 is an apparatus provided with a flow path 8 (318) in addition to the components of the gas separation apparatus of FIG. The flow path 8 connects a branch point to the most downstream module 341f on the flow path 3 and a point located between the raw material supply port 351 on the flow path 1 and the branch point to the most upstream module 341a. To do. In this apparatus, the non-permeating gas discharged from the modules (341c to 341f) in the second unit is supplied (recycled) into the flow path 1 through the flow path 8 (318). Thus, by recycling the non-permeating gas, the recovery rate of the high permeating gas and the low permeating gas from the raw material can be increased.

  Also in the seventh embodiment, as in the first embodiment, the number of modules constituting the first unit and the second unit can be easily adjusted only by selecting whether to open or close the valve. A compressor may be provided on the flow path 7. Further, similarly to Embodiments 4 and 5, by providing a valve, it can be used in a single stage or a purge gas can be supplied.

  The module in the apparatus of the present invention is not particularly limited as long as it includes three or more modules.

  Although the case where a hollow fiber membrane is used as the gas separation membrane has been described above, the gas separation membrane in the gas separation apparatus of the present invention may be a spiral type or a flat membrane. As the hollow fiber, a large number of hollow fibers having a small thickness and a small diameter can be used even in a small apparatus, can increase the membrane area, increase the separation efficiency, and are economical and preferable. Examples of the hollow fiber include those having a film thickness of 10 to 500 μm and an outer diameter of 50 to 2000 μm, but are not particularly limited. 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.

  Examples of the gas separation membrane include those formed of polyimide, polyetherimide, polyamide, polyamideimide, polysulfone, polycarbonate, silicone resin, a polymer material such as a cellulose-based polymer, or a ceramic material such as zeolite. As a gas separation membrane formed of polyimide, for example, an aromatic polyimide hollow fiber separation membrane is preferable, and an aromatic polyimide asymmetric hollow fiber separation membrane is more preferable.

  The form of the gas separation membrane module is not particularly limited, and those usually used can be used. Examples of the distribution form of the hollow fiber bundle include a parallel arrangement, a cross arrangement, a woven form, and a spiral form. 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. Further, 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 stored in the container as it is, bent into a U shape, or wound in a spiral shape.

  According to the present invention, even when the condition of the supplied mixed gas varies, a specific component among the components contained in the mixed gas can be separated and recovered with a high concentration and a high recovery rate. For example, biogas containing methane gas and carbon dioxide as main components can be separated and high concentration methane gas can be recovered at a high recovery rate. Further, helium or hydrogen can be separated and recovered from a gas containing helium or hydrogen, respectively. In particular, since the generation amount of biogas often fluctuates, it is preferable to use the apparatus of the present invention because the number of modules constituting the first stage and the second stage can be adjusted and the conditions can be easily set.

  Next, the present invention will be further described with reference to examples. In addition, this invention is not limited to a following example.

<Example 1>
A case of using a gas separation apparatus having a configuration shown in FIG. 13 using biogas containing 60 mol% of methane gas and 40 mol% of carbon dioxide as a raw material was examined. The gas separation apparatus has a configuration in which two gas separation membrane units (first stage and second stage) are connected in series. The gas separation membrane module used in this example has a carbon separation gas permeation rate (P ′ _CO2 ) of 26.4 × 10 ⁻⁵ Ncc / cm ² · s · cmHg, a methane gas permeation rate (P ′ _CH4 ) is 1.7 × 10 ⁻⁵ Ncc / cm ² · s · cmHg, and the gas separation membrane area per one is 11 m ² . In the gas separation apparatus, the first-stage gas separation membrane unit has four modules and the second-stage gas separation membrane unit has seven modules, and the raw material is supplied at a flow rate of 170 Nm ³ / h. The concentration of recovered methane gas (non-permeate gas) and the recovery rate of methane gas were calculated. As a result, the concentration of recovered methane gas was 95.3 mol%, and the recovery rate of methane gas was 88.7% (see Table 1). In the following examples and reference examples, it was aimed to obtain methane gas having a concentration of 95 mol% or more.

<Reference Example 1>
Calculation was performed for gas separation under the same conditions as in Example 1 except that the flow rate of the raw material was increased to a flow rate of 200 Nm ³ / h. The results are shown in Table 1. It was shown that when the flow rate of the raw material was increased, the concentration of recovered methane gas decreased.

<Example 2>
Except for adjusting the number of modules constituting the separation membrane unit, the concentration of methane gas and the recovery rate were calculated under the same conditions as in Reference Example 1. The calculation results are shown in Table 1. As a result of adjusting the number of modules, a high concentration of methane gas was obtained.

<Reference Example 2>
Calculation was performed for gas separation under the same conditions as in Example 1 except that the concentration of the raw material was reduced to a flow rate of 150 Nm ³ / h. The results are shown in Table 1. It was shown that when the flow rate of the raw material was decreased, the target methane gas concentration could be achieved, but the yield of recovered methane gas decreased.

<Example 3>
Except for adjusting the number of modules constituting the separation membrane unit, the concentration of methane gas and the recovery rate were calculated under the same conditions as in Reference Example 2. The calculation results are shown in Table 1. As a result of adjusting the number of modules, the methane gas recovery rate was improved while maintaining a high methane gas concentration.

  According to the present invention, in a gas separation apparatus including a plurality of gas separation membrane modules, an apparatus capable of configuring two units connected in series and adjusting the number of modules included in each unit by a simple method. Can be provided. Thereby, an operating condition can be changed flexibly according to a composition and supply amount of source gas.

DESCRIPTION OF SYMBOLS 11 Gas supply port 12 Permeate gas exhaust port 13 Non-permeate gas exhaust port 14 Hollow fiber membrane 15 Containers 16a and 16b Tube plates 211 and 215 Supply gas channel 212 and 216 Permeate gas channel 213 and 217 Channel 214 Channels 221a to 221f Gas separation membrane module 301 First gas separation membrane unit 302 Second gas separation membrane unit 311 Channel 1
312 Channel 2
313 Channel 3
314 Channel 4
315 channel 5
316 Channel 6
317 channel 7
318 channel 8
321a to 321e, 322a to 322e, 323a to 323e, 324 to 328 Valve 331a, 332a, 333a, 331f, 332f, 333f Branch passage 341a to 341f Gas separation membrane module 351 Raw gas supply port 352, 353 Permeated gas discharge port 354 Non Permeate gas recovery ports 361, 362, 363 Compressor 371 Branch points 372, 375 Gas supply ports 373, 376 Permeate gas exhaust ports 374, 377 Non-permeate gas exhaust ports 381-383 Branch point 384 Points on flow path

Claims (16)

Three or more gas separation membrane modules;
A supply gas flow path (flow path 1) connected to all gas separation membrane modules;
A non-permeate gas channel (channel 3) connected to all gas separation membrane modules;
A valve,
Comprising:
The valve is provided between the branch points connected to the gas separation membrane modules on the flow path 1 and the flow path 3,
By closing the valve on the flow path 1 and the valve on the flow path 3 between the same modules, the first gas separation membrane unit to which the source gas is supplied and the second gas separation membrane unit connected in series therewith are provided. Can be configured,
By selecting opening and closing of each valve, the number of gas separation membrane modules constituting the first gas separation membrane unit and the second gas separation membrane unit can be adjusted;
Furthermore, a point on the upstream side of the closed valve of the non-permeate gas flow path (flow path 3), and a point on the downstream side of the closed valve of the supply gas flow path (flow path 1), And a gas flow path (flow path 4) for supplying the non-permeated gas recovered from the first gas separation membrane unit to the second gas separation membrane unit.   Furthermore, a flow path for the permeated gas (flow path 2) connected to all the gas separation membrane modules and a valve provided between the branch points connected to the gas separation membrane modules on the flow path 2 are provided. The gas separator according to claim 1.   Furthermore, the gas separation of Claim 2 provided with the gas flow path (flow path 5) for supplying the permeated gas discharged | emitted from the said 2nd gas separation membrane unit to a said 1st gas separation membrane unit. apparatus.   The gas separation device according to claim 1, further comprising a valve on the flow path 4.   The gas separation device according to claim 3, further comprising a valve on the flow path 4 and the flow path 5.   The gas separation device according to claim 1, further comprising a compressor on the flow path 4.   Furthermore, the flow path 3 has a branched flow path 6, and a part of the non-permeated gas recovered from the second gas separation membrane unit by the flow path 6 is converted into the first gas separation membrane unit and / or The gas separation device according to any one of claims 1 to 6, which can be supplied as a purge gas into the second gas separation membrane unit.   A method for separating a mixed gas, wherein the gas separation device according to any one of claims 1 to 7 is used in a state in which one or more valves on the channel 1 and the channel 3 are closed between the same modules. . 6. The gas separation device according to claim 2, wherein one or more valves on the flow channel 1, the flow channel 2, and the flow channel 3 are closed between the same modules. A method for separating a mixed gas used in 1.   The gas separation device according to claim 4, wherein all the valves between the gas separation membrane modules on the flow path 1 and the flow path 3 are opened and the valves on the flow path 4 are closed. Gas single-stage separation method.   6. The gas separation apparatus according to claim 5, wherein all the valves between the gas separation membrane modules on the flow paths 1 to 3 are opened, and the valves on the flow paths 4 and 5 are closed. A single-stage separation method of mixed gas to be used. Three or more gas separation membrane modules;
A supply gas flow path (flow path 1) connected to all gas separation membrane modules;
A permeating gas channel (channel 2) connected to all gas separation membrane modules;
A valve,
Comprising:
The valve is provided between the branch points connected to the gas separation membrane modules on the flow channel 1 and the flow channel 2,
By closing the valve on the flow path 1 and the valve on the flow path 2 between the same modules, the first gas separation membrane unit to which the source gas is supplied and the second gas separation membrane unit connected in series therewith are provided. Can be configured, and
By selecting opening and closing of each valve, the number of gas separation membrane modules constituting the first gas separation membrane unit and the second gas separation membrane unit can be adjusted;
Further, a point upstream of the valve closed in the permeate gas flow path (flow path 2) and a point downstream of the valve closed in the supply gas flow path (flow path 1) A gas separation device comprising a gas flow path (flow path 7) for connecting and supplying the permeate gas recovered from the first gas separation membrane unit to the second gas separation membrane unit.   Furthermore, a valve provided between a non-permeate gas flow channel (flow channel 3) connected to all gas separation membrane modules and a branch point connected to the gas separation membrane module on the flow channel 3 is provided. The gas separator according to claim 12.   Furthermore, the gas separation apparatus of Claim 13 provided with the gas flow path (flow path 8) for supplying the non-permeating gas discharged | emitted from the 2nd gas separation membrane unit to a 1st gas separation membrane unit.   A method for separating a mixed gas, wherein the gas separation device according to any one of claims 12 to 14 is used in a state where one or more valves on the flow channel 1 and the flow channel 2 are closed between the same modules. . 15. A method for separating a mixed gas, wherein the gas separation device according to claim 13 or 14 is used in a state in which one or more valves on each of the flow path 1, the flow path 2, and the flow path 3 are closed between the same modules. .

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