WO2023100932A1

WO2023100932A1 - Gas separation membrane system and gas separation membrane regeneration method

Info

Publication number: WO2023100932A1
Application number: PCT/JP2022/044193
Authority: WO
Inventors: 叙彦福田; 智英中村; 洋樹印出
Original assignee: Ｕｂｅ株式会社
Priority date: 2021-12-01
Filing date: 2022-11-30
Publication date: 2023-06-08

Abstract

In this invention: a gas inlet (11a) of a first gas separation membrane unit (11) is connected with a line (6); a compression means (21) and a heating means (61) are provided in an intermediate portion of the line (6); an impermeable gas outlet (11b) of the unit (11) is coupled by a line (14) to a gas inlet (12a) of a second gas separation membrane unit (12); a permeable gas outlet (12c) of the unit (12) is coupled by a line (17) to the suction side position of the compression means (21) on the line (6); a permeable gas outlet (11c) of the unit (11) is connected with a line (19); an outlet (12b) of the unit (12) is connected with a line (18); and regeneration gas introduced into the line (6) is circulated through the unit (11) and the unit (12) after being heated by the heating means (61) to a temperature 10 °C to 80 °C higher than that in the normal operation.

Description

Gas separation membrane system and gas separation membrane regeneration method

The present invention relates to a gas separation membrane system and a method for regenerating a gas separation membrane used in the gas separation membrane system.

As a method for separating a raw material mixed gas containing two or more different gases into each gas, a membrane separation method that utilizes the difference in gas permeation speed with respect to a membrane is known. In this method, a raw material mixed gas containing two or more gases is supplied to a gas separation membrane and separated into a permeable gas enriched with a high-permeability gas and an impermeable gas enriched with a low-permeability gas. . Gas separation membranes are generally used as a separation membrane module in which a gas separation membrane having gas selective permeability is housed in a container provided with at least a gas inlet, a permeable gas outlet, and an impermeable gas outlet. ing. The gas separation membrane is mounted in the container so that the spaces on the gas supply side and the gas permeation side thereof are separated. In a gas separation membrane system, generally a plurality of separation membrane modules are combined in parallel and used in order to obtain a required membrane area.

The raw material mixed gas may itself contain high-boiling organic matter. In addition, oil mist from the compressor that supplies the raw material mixed gas to the gas separation membrane may be mixed into the raw material mixed gas. In those cases, the high-boiling organic matter and oil mist adhere to the gas separation membrane to which the raw material mixed gas is supplied. Depending on the amount of adhesion, the permeability of the gas separation membrane decreases over time.
In response to this problem, Patent Document 1 discloses that two or more gas separation systems are used to separate the supplied raw material mixed gas into a permeable gas and an impermeable gas, and the permeated gas separated in one gas separation system. The gas is supplied to the impermeable gas supply port of another module of the gas separation system to which the supply of the raw material mixed gas is stopped, and the impurities adhering to the hollow fiber membrane are removed along with the permeated gas. Techniques for regenerating separation membrane modules provided in other gas separation systems are described.

JP 2019-48276 A

US Pat. No. 5,300,004 relates to a single-stage gas system and also requires a complex system for regeneration.
On the other hand, conventionally, gas separation is known to be performed by a system in which multiple stages of gas separation membrane units are combined to improve the recovery rate and purity. However, in such a gas separation membrane system, no study has been made on regenerating the gas separation membrane without removing the separation membrane module from the gas separation membrane system.

Accordingly, an object of the present invention is to efficiently and easily restore the permeability of the gas separation membranes without removing the gas separation membrane module in a gas separation membrane system in which two stages of gas separation membrane units are combined. An object of the present invention is to provide a membrane system and a method for regenerating a separation membrane.

The present invention is a gas separation membrane system comprising at least a first gas separation membrane unit and a second gas separation membrane unit having gas separation performance,
each gas separation membrane unit comprises at least a gas inlet, a permeable gas outlet and an impermeable gas outlet;
A supply gas line is connected to the gas inlet of the first gas separation membrane unit, and compression means and heating means are interposed in the middle of the supply gas line,
connecting the impermeable gas outlet of the first gas separation membrane unit and the gas inlet of the second gas separation membrane unit by a first impermeable gas outlet line;
connecting the permeated gas outlet of the second gas separation membrane unit and a position on the suction side of the compression means in the supply gas line by a second permeated gas return line;
connecting a second impermeable gas discharge line to the impermeable gas discharge port of the second gas separation membrane unit;
connecting the first permeated gas discharge line to the permeated gas discharge port of the first gas separation membrane unit;
After heating the gas for regeneration of the gas separation membrane introduced into the supply gas line to a temperature higher by 10° C. or more and 80° C. or less than during operation for gas separation using the heating means, the first gas separation membrane unit and a second gas separation membrane unit.

The present invention also provides a method for regenerating a gas separation membrane in a gas separation membrane system comprising at least a first gas separation membrane unit and a second gas separation membrane unit having gas separation performance, comprising:
each gas separation membrane unit comprises at least a gas inlet, a permeable gas outlet and an impermeable gas outlet;
A supply gas line is connected to the gas inlet of the first gas separation membrane unit, and compression means and heating means are interposed in the middle of the supply gas line,
connecting the impermeable gas outlet of the first gas separation membrane unit and the gas inlet of the second gas separation membrane unit by a first impermeable gas outlet line;
connecting the permeated gas outlet of the second gas separation membrane unit and a position on the suction side of the compression means in the supply gas line by a second permeated gas return line;
connecting a second impermeable gas discharge line to the impermeable gas discharge port of the second gas separation membrane unit;
connecting the first permeated gas discharge line to the permeated gas discharge port of the first gas separation membrane unit;
After heating the gas for regeneration of the gas separation membrane introduced into the supply gas line to a temperature higher by 10° C. or more and 80° C. or less than during operation for gas separation using the heating means, the first gas separation membrane unit and a method for regenerating a gas separation membrane by circulating it in a second gas separation membrane unit.

The system further comprises a third gas separation membrane unit having gas separation performance,
the third gas separation membrane unit comprises at least a gas inlet, a permeable gas outlet and an impermeable gas outlet;
connecting the impermeable gas outlet of the third gas separation membrane unit and a position on the suction side of the compression means in the supply gas line by a third impermeable gas return line;
connecting the permeated gas discharge port of the first gas separation membrane unit and the gas inlet of the third gas separation membrane unit by the first permeated gas discharge line;
A third permeated gas discharge line may be connected to the permeated gas discharge port of the third gas separation membrane unit.

According to the present invention, in a gas separation membrane system in which two or more stages of gas separation membrane units are combined, the permeability of the gas separation membrane can be efficiently and easily regenerated without removing the gas separation membrane module. A membrane system and a method for regenerating a separation membrane are provided.

FIG. 1 is a schematic diagram showing an example of the gas separation membrane system of the present invention. FIG. 1(a) shows the gas flow path during operation for gas separation, and FIG. 1(b) shows the gas flow path during regeneration of the gas separation membrane. FIG. 2 is a schematic diagram showing the structure of an example of a separation membrane module used in the gas separation membrane system of the present invention. FIG. 3 is a schematic diagram showing another example of the gas separation membrane system of the present invention. FIG. 3(a) shows the gas flow path during operation for gas separation, and FIG. 3(b) shows the gas flow path during regeneration of the gas separation membrane. FIG. 4 is a schematic diagram showing another example of the gas separation membrane system of the present invention. FIG. 4(a) shows the gas flow path during operation for gas separation, and FIG. 4(b) shows the gas flow path during regeneration of the gas separation membrane. FIG. 5 is a schematic diagram showing another example of the gas separation membrane system of the present invention. FIG. 5(a) shows the gas flow path during operation for gas separation, and FIG. 5(b) shows the gas flow path during regeneration of the gas separation membrane. FIG. 6 is a schematic diagram showing an example of the gas separation membrane system of the present invention. FIG. 6(a) shows the gas flow path during operation for gas separation, and FIG. 6(b) shows the gas flow path during regeneration of the gas separation membrane. FIG. 7 is a schematic diagram showing another example of the gas separation membrane system of the present invention. FIG. 7(a) shows the gas flow path during operation for gas separation, and FIG. 7(b) shows the gas flow path during regeneration of the gas separation membrane. FIG. 8 is a schematic diagram showing another example of the gas separation membrane system of the present invention. FIG. 8(a) shows the gas flow path during operation for gas separation, and FIG. 8(b) shows the gas flow path during regeneration of the gas separation membrane. FIG. 9 is a schematic diagram showing another example of the gas separation membrane system of the present invention. FIG. 9(a) shows the gas flow path during operation for gas separation, and FIG. 9(b) shows the gas flow path during regeneration of the gas separation membrane. FIG. 10 is a schematic diagram showing another example of the gas separation membrane system of the present invention. FIG. 10(a) shows the gas flow path during operation for gas separation, and FIG. 10(b) shows the gas flow path during regeneration of the gas separation membrane. FIG. 11 is a schematic diagram showing another example of the gas separation membrane system of the present invention. FIG. 11(a) shows the gas flow path during operation for gas separation, and FIG. 11(b) shows the gas flow path during regeneration of the gas separation membrane.

The regeneration method and gas separation membrane system of the present invention will be described below based on preferred embodiments thereof.
In the present invention, the term "regeneration" refers to a decrease in the permeation gas flow rate (Nm ³ /h) due to deposition of impurities on the gas separation membrane, or improvement of the phenomenon associated with the decrease in the permeation gas flow rate. The phenomenon associated with the decrease in the flow rate of the permeating gas referred to here includes a decrease in the flow rate of the processing gas, a decrease in the purity of the product gas, and the like.

1, 3 to 11 respectively show gas separation membrane systems 10, 10', 10'', 10''', 110, 110', 110'', 110''', 110' of embodiments of the present invention. ''', 110''''' (hereinafter also referred to as '10 to 110'''''). In each of these figures, double lines indicate lines through which gas flows outside the gas separation membrane unit, and dotted lines indicate paths through which gas flows inside the gas separation membrane unit. Arrows indicate the direction of gas flow. On the other hand, a solid single line indicates a line through which no gas is flowing. On the other hand, a solid single line indicates a line through which no gas is flowing.
FIGS. 1 and 3 to 11 (a) show the gas separation membrane system in the gas separation membrane system during operation for gas separation and the gas flow paths in the system, and FIGS. 1 and 3 to 11 ( b) shows the gas separation membrane system and the gas flow path in the system during regeneration of the gas separation membrane.

The gas separation membrane systems 10 to 10''' shown in FIGS. 1 and 3 to 5 are provided with two gas separation membrane units, a first gas separation membrane unit 11 and a second gas separation membrane unit 12. 110 to 110'''' described in FIGS. As the

units

11, 12, and 13, for example, as shown in FIG. 2, a module 40 can be used in which a gas separation membrane 20 made of a hollow fiber membrane or the like and having gas selective permeability is accommodated in a casing 31. . Each of the gas

separation membrane units

11, 12, 13 of this embodiment uses one gas separation membrane module 40 shown in FIG. 2, or a plurality of such modules 40 are arranged in parallel. .

In the present embodiment, the separation membrane module is a container containing a plurality of hollow fiber membranes having gas separation performance. Hollow fiber membranes can be made compact and have a large membrane area, so they are efficient and economical. The hollow fiber membrane may be homogeneous or heterogeneous such as a composite membrane or an asymmetric membrane, and may be microporous or nonporous. Preferably, the hollow fiber membrane has a thickness of 10 to 500 μm and an outer diameter of 50 to 2000 μm. Hollow fiber membranes are made of polymer materials such as polyimide, polyetherimide, polyamide, polyamideimide, polysulfone, polycarbonate, silicone resin, and cellulose-based polymers, materials obtained by carbonizing or partially carbonizing polymer materials, and ceramic materials such as zeolite. A suitable gas separation membrane can be mentioned. In particular, an asymmetric polyimide gas separation membrane is preferable because it not only has high gas separation performance but also excellent properties such as heat resistance, durability, and solvent resistance.

In a separation membrane module, a large number of hollow fiber membranes (for example, hundreds to hundreds of thousands) are bundled to form a hollow fiber membrane bundle, and at least one end of the hollow fiber membrane bundle is coated with a material such as epoxy resin. A hollow fiber separation membrane element is formed by fixing a hollow fiber membrane element with a thermosetting resin, a hot-melt thermoplastic resin, or the like so that the hollow fiber membranes are open at the ends. The thread element is mounted in a container having at least a gas inlet, a permeable gas outlet, and an impermeable gas outlet, so that the space leading to the inside of the hollow fiber membrane and the space leading to the outside of the hollow fiber membrane are isolated. configured as follows. Containers are manufactured from composite materials such as metal materials such as stainless steel, plastic materials, and fiber-reinforced plastic materials.

The form of the separation membrane module is not particularly limited and may be one commonly used. The fiber arrangement form of the hollow fiber membrane bundle may be a parallel arrangement, a cross arrangement, a woven fabric, a spiral, or the like. Further, the hollow fiber membrane bundle may have a core tube substantially at the center, and a film may be wound around the outer peripheral portion of the hollow fiber membrane bundle. Furthermore, the shape of the hollow fiber membrane bundle may be cylindrical, flat, prismatic, or the like, and may be stored in the container as it is, or may be stored in the container while being bent in a U-shape or wound in a spiral.

An example of the separation membrane module is shown as module 40 in FIG. In FIG. 2, the casing 31 in the module 40 is open on two opposite sides to form an opening 32 . It should be noted that this opening 32 is for inserting the gas separation membrane 20 into the casing 31 and is not an opening in the gas separation membrane 20 . The gas separation membrane 20 is housed inside the casing 31 through this opening 32 . When the gas separation membrane 20 consists of a bundle of hollow fiber membranes, the gas separation membrane 20 is arranged in the casing 31 so that each end of the hollow fiber membrane is open near each opening 32 of the casing 31 in the housed state. are housed in

When the gas separation membrane 20 is accommodated in the casing 31, the gas separation membrane 20 is fixed to the inner wall of the casing 31 by the

tube plates

33 and 34 at both ends in the Y direction, which is the direction in which the hollow fiber membranes extend. It is Each opening 32 of the casing 31 is closed by

lids

35 and 36 . A gas inlet 37 is provided in the lid 35 . On the other hand, the lid 36 is provided with an impermeable gas outlet 38 . A gas to be separated is introduced into the module from the gas inlet 37 of the lid 35 . Of the introduced gas, the gas that permeates the gas separation membrane 20 is discharged outside the module from the permeated gas discharge port 39 provided in the casing 31 . On the other hand, the impermeable gas that has not permeated the gas separation membrane 20 is discharged from the impermeable gas outlet 38 of the lid 36 to the outside of the module. In some cases, the casing 31 may be provided with a purge gas supply port (not shown).

The separation membrane module is not limited to the hollow feed type shown in FIG. 2, but may be 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 a carrier gas, a carrier gas introduction port is arranged in the container, or a carrier gas introduction pipe is arranged as a core tube of the hollow fiber membrane bundle.

Returning to FIG. 1, as shown in the figure, the first gas separation membrane unit 11 and the second gas separation membrane unit 12 are connected in series. Specifically, the first gas separation membrane unit 11 and the second gas separation membrane unit 12 are separated from the impermeable gas outlet 11b of the first gas separation membrane unit 11 and the gas inlet of the second gas separation membrane unit 12. 12a are connected by a first impermeable gas discharge line 14. As shown in FIG.

At the gas inlet 11a of the first gas separation membrane unit 11, a raw mixed gas from a mixed gas source (not shown), which is a raw material, is supplied to the first gas separation membrane unit 11, and from the gas source (not shown) A supply gas line 6 for supplying regeneration gas to the first gas separation membrane unit 11 and the second gas separation membrane unit 12 is connected. A compressing means 21 is interposed in the middle of the supply gas line 6 . The compressing means 21 is installed for the purpose of compressing the raw material mixed gas supplied from the gas source and the permeating gas returned from the second gas separation membrane unit 12, and compressing the regeneration gas. As the compression means 21, the same means as have been used so far in the relevant technical field can be used. For example, a compressor (compressor) can be used.

In addition, the "raw material mixed gas" in this specification means the target gas for gas separation supplied to the gas separation membrane system. Normally, the raw material mixed gas is supplied to the separation membrane module 40 in a state of being compressed by a compressor or the like. Specifically, raw material mixed gases containing two or more kinds of gases include air, biogas, natural gas, by-product gas and exhaust gas from petrochemical plants, various thermal decomposition gases, and the like. The two or more gases contained in the raw material mixed gas include H ₂ , He, CO, CO ₂ , O ₂ , N ₂ , H ₂ O, H ₂ S, organic vapor, CH ₄ , C ₂ H ₆ and ethanol. , methanol, ketones, hydrocarbons having 3 or more carbon atoms (hereinafter also referred to as “C3 ⁺ ”), and the like, any combination of which has a different permeation rate with respect to the hollow fiber membrane 20 . The composition of the raw material mixed gas after being introduced into the gas separation membrane system may change depending on whether or not it permeates the gas separation membrane. Hereinafter, when explaining the flow path of the raw material mixed gas during normal operation, the term "separation target gas" may be used for the raw material mixed gas whose composition has changed due to permeation or non-permeation of the gas separation membrane.

Although the types of the raw material mixed gas and the separation membrane module are not limited, for example, the separation membrane module 40 to which the raw material mixed gas is supplied has a higher permeation rate of carbon dioxide (CO ₂ ) than that of methane (CH ₄ ). and a gas containing CH ₄ and CO ₂ as _the raw material mixed gas _; and a gas containing N ₂ and O ₂ as the raw material mixed gas. Raw material mixed gases containing CH ₄ and CO ₂ include biogas, landfill gas and natural gas. Moreover, air is mentioned as raw material mixed gas containing _N2 and _O2 . Note that biogas is a gas that is generated when a biomass raw material is brought into contact with microorganisms under anaerobic conditions and fermentation such as methane fermentation is performed by the microorganisms. Biomass raw materials include organic matter such as food waste, agricultural residue, sewage sludge, and livestock waste. Landfill gas refers to gas generated by microbial decomposition of organic matter in waste landfill sites. Biogas and landfill gas are typically composed primarily of methane and carbon dioxide.

Impurities in the present embodiment include moisture and dust contained in the raw material mixed gas, high boiling point components, oil and oil mist mixed from the compressor, and the like. Impurities are usually organic. Examples of organic impurities include aliphatic hydrocarbons, aromatic hydrocarbons, sulfur-containing compounds, silicon-containing compounds, ketones, esters, and fatty acids. These may be substituted with halogen such as chlorine. For example, in a separation membrane module in which biogas or landfill gas is supplied as a raw material mixed gas, hydrocarbons having 3 or more carbon atoms can be mentioned, and specific examples include acetone, 4-methyl-2-pentanone, and the like. ketones; higher fatty acids such as palmitic acid and salts and esters thereof; saturated or unsaturated aliphatic alcohols such as 2-methyl-3-buten-2-ol; aromatics such as toluene, benzene, ethylbenzene, dimethylbenzene, and cymene long-chain or branched-chain or cyclic alkanes such as hexane, cyclohexane, n-octane, n-nonane, 2,2,4-trimethylpentane (isooctane); thiolenes, thiols, thioethers, 3- Thiophenes such as methylthiophene, sulfur-containing compounds such as thioalkanes such as 1-methylthiopropane; heterocycle-containing compounds; 2,6-dimethyl-4-octene, 2,6-dimethyl-1,7-diotadiene, 3,7 - long-chain or branched unsaturated aliphatic compounds (alkenes) such as dimethyl-1,7-diotadiene, 5-methyl-4-nonene, 3,7-dimethyl-2-octene; saturated compounds such as 3-mentene; or terpenes such as unsaturated aliphatic ring-containing compounds, camphor, limonene, α-pinene, β-pinene; and siloxanes. Further, as components of compressor oil mist, short-chain, long-chain or branched alkanes; short-chain, long-chain or branched-chain or Cyclic alcohols; short, long, branched, or aromatic cyclic esters; short, long, or branched organic acids; short, long, or branched ketones; aromatic hydrocarbons. These may be substituted with halogen or the like. The forms in which these adhere to the hollow fiber membrane 20 include condensing or adsorbing on the surface of the hollow fiber membrane 20 or inside the membrane.

Returning to FIG. 1, a heating means 61 is interposed in the middle of the supply gas line 6 . The heating means 61 is mainly arranged to heat the regeneration gas and supply it to the first gas separation membrane unit 11 and the second gas separation membrane unit 12 . The heating means 61 may be used to bring the gas supplied to the first gas separation membrane unit 11 to a predetermined temperature during operation for gas separation. It is preferable that the heating means 61 be arranged on the first gas separation membrane unit 11 side of the compression means 21 in order to facilitate temperature control of the gas supplied to the first gas separation membrane unit 11 . As the heating means 61, the same means as have been used in the relevant technical field can be used. For example, a heater using electricity, gas, or the like as a heat source can be used.

In the second gas separation membrane unit 12 , the permeated gas discharge port 12 c is connected to the suction side of the compression means 21 in the supply gas line 6 by the second permeated gas return line 17 . A second impermeable gas discharge line 18 is connected to the impermeable gas discharge port 12 b of the second gas separation membrane unit 12 . A first permeated gas discharge line 19 is connected to the permeated gas discharge port 11 c of the first gas separation membrane unit 11 .

The gas path during operation for gas separation (hereinafter also referred to as "normal operation") in the gas separation membrane system 10 of this embodiment having the above configuration will be described based on FIG. 1(a). A raw material mixed gas to be separated is supplied from a mixed gas source (not shown) through a supply gas line 6 to the first gas separation membrane unit 11 . Prior to supply, the mixed gas is pressurized by compression means 21 to increase its pressure.

As shown in FIG. 1( a ), the raw material mixed gas is two different types of gases to be separated, which are the gas A having a high permeation rate through the gas separation membrane and the permeation through the gas separation membrane compared to the gas A. It contains at least the gas B with low polarities. When the raw material mixed gas pressurized by the compression means 21 is supplied to the first gas separation membrane unit 11, due to the difference in the permeation speed with respect to the gas separation membrane, the permeation gas, which is the gas that has permeated the gas separation membrane, It is separated into a gas and an impermeable gas, which is the gas that did not permeate the gas separation membrane. The impermeable gas discharged from the first gas separation membrane unit 11 is discharged from the impermeable gas discharge port 11b of the first gas separation membrane unit 11, and passes through the first impermeable gas discharge line 14 to the second gas separation membrane unit 12. supplied to On the other hand, in the permeated gas from the first gas separation membrane unit 11 , the gas A is more concentrated than the raw material mixed gas, and is taken out of the system through the first permeated gas discharge line 19 . The impermeable gas discharged from the impermeable gas outlet 11 b of the first gas separation membrane unit 11 is introduced into the second gas separation membrane unit 12 . The gas introduced into the second gas separation membrane unit 12 is separated into a permeable gas and an impermeable gas by the same unit 12 . In the impermeable gas, the gas B is further concentrated and enriched compared to the gas introduced into the second gas separation membrane unit 12, and the second impermeable gas discharge line 18 is discharged from the impermeable gas discharge port 12b of the same unit 12. It is taken out of the system through On the other hand, the permeated gas is discharged from the permeated gas outlet 12c of the second gas separation membrane unit 12 and is compressed in the supply gas line 6 via the second permeated gas return line 17 connected to the outlet 12c. It is fed back to the suction side of means 21 . The returned permeated gas is pressurized by the compression means 21 after being mixed with the raw material mixed gas.

After the above normal operation has passed for a certain period of time, the organic impurities in the raw material mixed gas adhere to the first gas separation membrane unit 11 and the second gas separation membrane unit 12, so that the first gas separation membrane unit 11 and the second gas The gas permeation performance of the separation membrane unit 12 is lowered. At this time, by heating the regeneration gas with the heating means 61 and circulating it through the first gas separation membrane unit 11 and the second gas separation membrane unit 12, the first gas separation membrane unit 11 and the second gas separation membrane unit 12 are Organic impurities are volatilized and removed from the unit 12 to restore the permeation performance.

FIG. 1(b) shows the flow path of regeneration gas during regeneration of the gas separation membrane in the gas separation membrane system 10 shown in FIG. As shown in FIGS. 1(a) and 1(b), in the gas separation membrane system 10 shown in FIG. It is the same as the gas distribution route of the target gas. The regeneration gas may be the same as the raw material mixed gas, or may be different. Examples of regenerative gases include biogas, landfill gas, air, nitrogen, and natural gas. It is preferable to use nitrogen, air, and a raw material mixed gas during operation for gas separation as the regeneration gas, particularly from the viewpoint of ease of procurement of the regeneration gas. Further, when the gas separation membrane of the first gas separation membrane unit 11 is a polyimide membrane having a separation selectivity _P'O2 / _P'N2 at 40°C of 4 to 8, particularly preferably 5 to 7, By using air, an appropriate amount of regeneration gas permeates the gas separation membrane of the first gas separation membrane unit 11 to remove impurities adhering to the permeation side of the gas separation membrane of the same unit 11, while separating the second gas. This is preferable in that a sufficient amount of impermeable gas can be reliably sent to the membrane unit 12 to increase the regeneration efficiency of the second gas separation membrane unit 12 . In this case, from the viewpoint of regeneration efficiency of the second gas separation membrane unit 12, the gas separation membranes constituting the second gas separation membrane unit 12 have a _P'O2 / _P'N2 ratio of 4 to 8 at 40°C. Preferably. For example, the examples described later use polyimide membranes having separation selectivities within these ranges. The above P′ is the permeation rate, which is the permeation volume per unit membrane area, unit time, and unit partial pressure difference with respect to the membrane of gas, and the unit is (×10 ⁻⁵ cm ³ (STP)/cm ² ·sec·cmHg).
In order to prevent complication of the system, it is preferable not to use the permeated gas of another module outside the gas separation membrane system as the regeneration gas. However, "not using the permeated gas of another module as the regeneration gas" here means that the regeneration gas is first circulated in the gas separation membrane system, and another module outside the gas separation membrane system is used. This means that no permeating gas is used. For this reason, "not using the permeated gas from another module as regeneration gas" means that in the system of FIG. allow the case. Incidentally, the regeneration gas is separated into a permeable gas and an impermeable gas by the gas separation membrane, so that the gas composition may differ from the beginning of the introduction of the system. It is also preferable that the present regeneration method does not use the permeated gas of the same module in the gas separation membrane system as the regeneration gas. The present invention regenerates a gas separation membrane module while it is placed in a gas separation system.

In the present invention, the gas for regeneration of the gas separation membrane introduced into the supply gas line 6 is heated to a temperature higher by 10° C. or more and 80° C. or less than the operating temperature T1 for gas separation using the heating means 61. , the first gas separation membrane unit and the second gas separation membrane unit. The temperature T1 during operation for gas separation here means the separation target gas (here, the mixture of the raw material mixed gas and the return gas) when introduced into the first gas separation membrane unit 11 during the operation for gas separation. gas) temperature. In the present invention, regardless of the form described below, the difference between the gas temperature at the time when the regeneration gas is first introduced into any of the gas separation membrane units 11 to 13 and the above T1 is 10° C. or more. 80°C or less.
In this embodiment, the gas for regeneration is heated by the heating means 61 to a temperature higher by 10° C. or more and 80° C. or less than the gas temperature T1 during operation (during normal operation) for gas separation. It is introduced into the membrane unit 11 . Hereinafter, the temperature of the regeneration gas introduced into the first gas separation membrane unit 11 is also referred to as T2, and the temperature of the regeneration gas introduced into the second gas separation membrane unit 12 is also referred to as T4.
The temperature T2 is the temperature of the regeneration gas at the gas inlet of the first gas separation membrane unit 11 in the embodiments of FIGS. By setting (T2-T1) to 10°C or higher, the regeneration efficiency of the gas separation membrane is increased, and by setting (T2-T1) to 80°C or lower, the heating means prevents an excessive amount of heat required during normal operation. There are advantages such as From this point of view, (T2-T1) is more preferably 20°C or higher and 80°C or lower, and particularly preferably 30°C or higher and 80°C or lower. Preferably, T1 is usually 5°C or higher and 60°C or lower.
T2 is preferably 40° C. or higher and 120° C. or lower.
The present inventors have found that good regeneration efficiency can be obtained without heating the gas separation membranes themselves by circulating a high-temperature gas in a predetermined gas separation membrane system with two or more stages.

Furthermore, in the present embodiment, it is preferable to remove impurities by supplying the regeneration gas to the first gas separation membrane unit 11 at a pressure below a certain level. In the embodiment of FIG. 1, the pressure of the regeneration gas supplied to the first gas separation membrane unit 11 is a pressure for reliably circulating the regeneration gas to the first gas separation membrane unit and the second gas separation membrane unit. 0.2 MPaG or more and 1.4 MPaG or less is more preferable, and 0.3 MPaG or more and 1.2 MPaG or less is still more preferable, for the reason of securing and preventing an increase in energy accompanying high pressure. The supply pressure in the second gas separation membrane unit 12 may be in the same range (the same applies to other embodiments hereinafter).

During regeneration, the gas supply amount S2 to the unit into which the regeneration gas flows second (in this embodiment, the second gas separation membrane unit 12) is the unit into which the regeneration gas flows first (in this embodiment, the first unit). The ratio S2/S1 to the gas supply amount S1 to the gas separation membrane unit 11) is 10% or more in terms of enhancing the effect of simultaneously regenerating the first gas separation membrane unit 11 and the second gas separation membrane unit 12. It is preferably 20% or more, more preferably 30% or more. Also, the S2/S1 ratio may be 95% or less, or 90% or less.

Further, during regeneration, the gas return amount S4 of the permeating gas of the second gas separation membrane unit 12 to the first gas separation membrane unit 11 has a ratio S4/S2 to the gas supply amount S2 to the second gas separation membrane unit 12. It is preferably 90% or less, more preferably 80% or less, from the viewpoint of suppressing the load on the compression means 21 and the like due to the return gas. The S4/S2 ratio may be 0%, but when the permeating gas of the second gas separation membrane unit 12 is returned to the first gas separation membrane unit 11, it may be 10% or more, or 20% or more. good too.

In the two-stage system, during regeneration, the gas supply pressure G2 to the unit into which the regeneration gas flows second (the second gas separation membrane unit 12 in this embodiment) is the same as the unit into which the regeneration gas flows first. The ratio G2/G1 to the gas supply pressure G1 to (in this embodiment, the first gas separation membrane unit 11) is 10% or more. It is preferable from the point of enhancing the effect of regeneration, more preferably 20% or more, and even more preferably 50% or more. G2/G1 may be 95% or less, or 90% or less.

At the time of regeneration, the amount of gas supplied to the unit into which the regeneration gas flows first among the units 11 to 13 (the first gas separation membrane unit 11 in this embodiment) is the first gas separation membrane unit 11 and the second gas separation membrane unit 11. From the viewpoint of enhancing the effect of simultaneously regenerating the gas separation membrane unit 12, it is preferably 10% or more, more preferably 20% or more, of the normal operation.

From the viewpoint of efficiently reproducing the two units, the reproduction time in this method is preferably 10 minutes or longer, and more preferably 20 minutes or longer.

In this embodiment, as shown in FIG. 1(b), the regeneration gas heated by the heating means 61 can be immediately circulated to the first gas separation membrane unit 11, and the gas separation membrane of the first gas separation membrane unit 11 is heated. By contacting the gas for regeneration, the organic impurities adhering to the gas separation membrane are volatilized. Some of the volatilized organic impurities are difficult to permeate the gas separation membrane system. Therefore, a certain proportion of the organic impurity volatiles adhering to the gas separation membranes of the first gas separation membrane unit 11 is introduced into the second gas separation membrane unit 12 along with the impermeable gas. In order to prevent the impermeable gas discharged from the first gas separation membrane unit 11 from contacting the gas separation membrane of the second gas separation membrane unit 12 and condensing, the gas separation membrane of the second gas separation membrane unit 12 Although the impermeable gas of the first gas separation membrane unit 11 may be introduced into the second gas separation membrane unit 12 in a heated state, in the present invention, the permeability of the gas separation membrane is improved without such preheating of the separation membrane. recovery is possible.

In addition, there are cases where volatilized organic impurities are contained in the permeated gas of the gas separation membrane. In this case, the permeated gas is taken out from the permeated gas discharge line 19 of the first gas separation membrane unit 11, and the permeated gas of the second gas separation membrane unit 12 is sent through the second permeated gas return line 17 to the supply gas line 6. is returned to A filter (not shown) using activated carbon or the like is interposed between the second permeated gas return line 17 and the confluence point of the compression means 21 and the line 17 in the supply gas line 6, or between the compression means 21 and the heating means 61. By the time the permeate gas discharged from the permeate gas discharge port 12 c returns to the supply gas line 6 , the organic impurities contained in the permeate gas may be removed.

As described above, in the embodiment shown in FIG. 1, it is possible to regenerate the separation membranes of the first gas separation membrane unit 11 and the second gas separation membrane unit 12 without installing a regeneration line.

As shown in FIG. 1(b), the temperature T4 of the regeneration gas when introduced into the second gas separation membrane unit 12 is the same as that of the second gas separation membrane unit during operation for gas separation (during normal operation). The difference (T4-T3) from the temperature T3 of the gas to be separated introduced into the 12 gas inlets is preferably 20°C or higher and 80°C or lower, more preferably 30°C or higher and 80°C or lower. T3 is usually preferably 5°C or higher and 60°C or lower, and T4 is preferably 40°C or higher and 120°C or lower. In this embodiment, T4 is the temperature of the regeneration gas when it is introduced into the gas inlet of the second gas separation membrane unit 12 .
In addition, the temperature T4 of the regeneration gas when introduced into the gas inlet of the second gas separation membrane unit 12 is equal to that at the gas inlet of the first gas separation membrane unit 11 during operation for gas separation (during normal operation). The difference (T4-T1) between the temperature T1 of the separation target gas introduced and the difference (T2-T3) between the temperatures T3 and T2 of the separation target gas introduced into the gas inlet of the second gas separation membrane unit 12 are also The temperature is preferably 20° C. or higher and 80° C. or lower, and more preferably 30° C. or higher and 80° C. or lower.

As an advantage of this embodiment, in addition to the fact that it is not necessary to install a regeneration line, compared to the case where the first gas separation membrane unit and the second gas separation membrane unit are removed from the gas separation membrane system and individually regenerated Since the high-temperature gas for regeneration can be shared between the first gas separation membrane unit and the second gas separation membrane unit, there is an advantage that the amount of heat required for heating the regeneration gas can be suppressed.

Next, another embodiment of the present invention will be described based on FIG. In FIG. 3, the same reference numerals are assigned to the same configurations as those shown in FIG. In the embodiment of FIG. 3, differences from the embodiment of FIG. 1 will be mainly described, and descriptions of the same points as those of FIG. 1 will be omitted.

In the embodiment of FIG. 3, a second permeated gas discharge line 22 branched from the second permeated gas return line 17 is provided so that when the regeneration gas is introduced into the second gas separation membrane unit 12, the second gas separation membrane The permeated gas from the unit 12 is discharged out of the system through the second permeated gas discharge line 22 without returning to the supply gas line 6 .

As shown in FIG. 3, the second permeated gas discharge line 22 is located at a position 22a in the second permeated gas return line 17 from the permeated gas discharge port 12c to the supply gas line 6 (hereinafter also referred to as a "branch point"). ) is a branch line branching from This is preferable because it facilitates switching of the flow path of the permeated gas discharged from the second gas separation membrane unit 12 . During operation for gas separation, the gas in the second permeated gas return line 17 does not flow into the second permeated gas discharge line 22 (FIG. 3(a)), and during regeneration, the second permeated gas return line 17 and the second The permeated gas discharge line 22 is conducted so that the permeated gas discharged from the second gas separation membrane unit 12 is introduced into the second permeated gas discharge line 22 at a branch point 22a. During regeneration, it is preferable that all the permeated gas discharged from the second gas separation membrane unit 12 is introduced into the second permeated gas discharge line 22 . Such switching is performed using a valve (not shown) at the branch point 22a. The second permeated gas discharge line 22 connects the outside of the system and the middle position of the second permeated gas return line 17 . In this specification, all means no intentional exceptions, and the intention is that unavoidable exceptions are permitted.

As described above, the permeated gas from the second gas separation membrane unit 12 does not flow through the second permeated gas discharge line 22 during operation for gas separation as shown in FIG. It is returned to the feed gas line 6 through the return line 17 . As shown in FIG. 3(a), the flow path of the gas to be separated during operation for gas separation is the same as in the embodiment of FIG. On the other hand, as shown in FIG. 3(b), during regeneration, the permeated gas from the second gas separation membrane unit 12 is discharged from the second permeated gas discharge line 22 without returning to the supply gas line 6. It is designed to be discharged outside the system.

According to the embodiment of FIG. 3 described above, when the gas separation membrane is regenerated, it volatilizes from the state attached to the gas separation membrane of the second gas separation membrane unit 12 and is contained in the permeated gas of the second gas separation membrane unit 12. The organic impurities that have become solidified can be immediately removed out of the system through the second permeated gas discharge line 22 without returning to the supply gas line 6 .
Therefore, in this embodiment, the first gas separation membrane unit 11 and the second gas separation membrane unit 12 are more efficiently operated while reducing the regeneration time, the compressor power required for regeneration, etc., as compared with the embodiment of FIG. It is preferable in that it is possible to regenerate the gas separation membrane in.

In addition, by adopting this embodiment, the impurity-containing gas fed back via the second permeated gas return line 17 to the supply gas line 6 and the filter (not shown) interposed between the compression means and the heating means. It is also preferable in terms of reducing the load of the regeneration gas.

For example, when regenerating the second gas separation membrane unit 12, if there is a high tendency for organic impurities to be contained in the gas permeating the gas separation membrane of the second gas separation membrane unit 12, the advantage of adopting the line 22 increases. Whether the organic impurities are contained in the permeating gas of the gas separation membrane of the second gas separation membrane unit 12 or in the impermeable gas depends on the type of raw material mixed gas during operation for gas separation and the regeneration gas. type, the temperature of the regeneration gas, and the type of impurities. As a regeneration gas having a line 22 as shown in FIG. 3, there is a high tendency for organic impurities to be contained in the gas permeating the gas separation membrane of the second gas separation membrane unit 12 during regeneration.

3 and subsequent figures, the preferred ranges of T1 to T4 and the preferred ranges of T2-T1, T4-T3, T4-T1 and T2-T3 are all the same as in the form of FIG. In addition, in the embodiment of FIG. 3, the pressure of the regeneration gas supplied to the first gas separation membrane unit 11 is set to ensure the circulation of the regeneration gas to the first gas separation membrane unit and the second gas separation membrane unit. In order to secure the pressure and prevent an increase in energy due to high pressure, it is more preferably 0.2 MPaG or more and 1.4 MPaG or less, and still more preferably 0.3 MPaG or more and 1.2 MPaG or less.

Furthermore, instead of the forms shown in FIGS. 1 and 3, the form shown in FIG. 4 can also be used. In FIG. 4, the same reference numerals are assigned to the same configurations as those shown in FIG. In the embodiment of FIG. 4, differences from the embodiments of FIGS. 1 and 3 will be mainly described, and description of the same points as those of the embodiments of FIGS. 1 and 3 will be omitted.

The embodiment of FIG. 4 has a first bypass line 23 and a first inlet gas discharge line 24 in addition to the second permeated gas discharge line 22 described above.
The first bypass line 23 connects the position of the heating means 61 in the supply gas line 6 on the first gas separation membrane unit 11 side and the second impermeable gas discharge line 18 . The first inlet gas discharge line 24 branches off from the supply gas line 6 on the first gas separation membrane unit 11 side of the connection point 23 a of the first bypass line 23 of the supply gas line 6 . The first inlet gas discharge line 24 is a line that connects the outside of the system and the supply gas line 6 .

According to the embodiment of FIG. 4, as shown in FIG. 4(a), during operation for gas separation (during normal operation), from the supply gas line 6 to the first bypass line 23 and the first inlet gas discharge line 24 gas is prevented from flowing into the On the other hand, as shown in FIG. 4B, during regeneration, gas flows from the supply gas line 6 into the first bypass line 23, and the gas to be separated flows from the connection point 23a of the supply gas line 6 with the first bypass line 23. Gas is prevented from flowing to the first gas separation membrane unit 11 side in the direction of flow. This switching of the gas flow path is performed by a valve (not shown) arranged at the connection point 23 a between the first bypass line 23 and the supply gas line 6 .

In the supply gas line 6, at the connecting point 24a of the first inlet gas discharge line 24 (hereinafter also referred to as "branch point 24a"), as described above, the gas from the supply gas line 6 flows into the first inlet during normal operation. Although it does not flow into the gas discharge line 24 (FIG. 4(a)), gas is introduced into the first inlet gas discharge line 24 from the first gas separation membrane unit 11 side of the connection point 24a in the supply gas line 6 during regeneration. , gas is prevented from flowing from the branch point 24a of the supply gas line 6 to the connection point 23a. This switching of the gas flow path is performed by a valve (not shown) arranged at a branch point 24 a of the first inlet gas discharge line 24 from the supply gas line 6 .

With the above configuration, as shown in FIG. 4(a), the gas to be separated passes through the same gas flow path as in FIGS. 1 and 3 during normal operation. In other words, the gas to be separated that flows through the supply gas line 6 and is pressurized by the compression means 21 is introduced into the first gas separation membrane unit 11 without passing through the first bypass line 23 .

On the other hand, as shown in FIG. 4(b), during regeneration, the regeneration gas that flows through the supply gas line 6 and is pressurized by the compression means 21 is heated by the heating means 61 and flows through the first bypass line. After being introduced into the second impermeable gas discharge line 18 through 23, normal operation is performed in the line 18 from the connection point 23b via the connection point 23b with the first bypass line 23 in the second impermeable gas discharge line 18. It flows in the reverse direction and is introduced into the second gas separation membrane unit 12 from the impermeable gas discharge port 12b.

Of the regeneration gas introduced from the impermeable gas outlet 12b of the second gas separation membrane unit 12, the gas that has permeated the gas separation membrane is discharged from the permeable gas outlet 12c, and the impermeable gas is discharged from the gas inlet 12a. be done. The impermeable gas discharged from the gas inlet 12 a of the second gas separation membrane unit 12 is introduced into the first gas separation membrane unit 11 from the impermeable gas discharge port 11 b through the first impermeable gas discharge line 14 . Of the impermeable gas (regeneration gas) introduced into the first gas separation membrane unit 11, the permeable gas is taken out of the system through the permeable gas outlet 11c and the first permeable gas discharge line 19. On the other hand, the impermeable gas is discharged from the gas inlet 11a of the first gas separation membrane unit. The impermeable gas (regenerating gas) discharged from the gas inlet 11a of the first gas separation membrane unit is introduced into the first inlet gas discharge line 24 branched from the supply gas line 6, and the first inlet gas is discharged. It circulates through the line 24 and is discharged outside the system.

According to the embodiment of FIG. 4 described above, by causing the heated regeneration gas to flow back through the impermeable gas circulation spaces of the gas separation membrane modules that constitute the first gas separation membrane unit 11 and the second gas separation membrane unit 12, There is an advantage that organic impurities adhering to the impermeable side of the gas separation membrane in the gas separation membrane module can be effectively removed. When the impermeable gas of the second gas separation membrane unit 12 containing volatile organic impurities attached to the gas separation membrane of the second gas separation membrane unit 12 contacts the gas separation membrane of the first gas separation membrane unit 11 In order to prevent the organic impurities from condensing, the regeneration gas may be passed through the first gas separation membrane unit 11 while the gas separation membranes of the first gas separation membrane unit 11 are heated.

Further, by adopting this embodiment, when the degree of contamination of the first gas separation membrane unit 11 is higher than that of the second gas separation membrane unit 12, the gas is discharged from the first gas separation membrane unit 11 during regeneration. It is possible to easily prevent the impurities removed from adhering to the gas separation membrane of the second gas separation membrane unit 12, which has a relatively low degree of contamination, and the second impermeable gas discharge line 18 is the product during normal operation. When connected to a downstream system such as a gas supply system, it is also preferable in that the downstream system is not contaminated by the impurity-containing regeneration gas.

As the temperature T2 of the regeneration gas introduced into the first gas separation membrane unit 11 in the embodiment of FIG. adopt. As the temperature T4 of the regeneration gas introduced into the second gas separation membrane unit 12, the temperature T4' of the regeneration gas introduced into the impermeable gas outlet of the second gas separation membrane unit 12 is employed. In the embodiment of FIG. 4, the pressure of the regeneration gas supplied to the second gas separation membrane unit 12 is a pressure for reliably circulating the regeneration gas to the first gas separation membrane unit and the second gas separation membrane unit. 0.2 MPaG or more and 1.4 MPaG or less is more preferable, and 0.3 MPaG or more and 1.2 MPaG or less is still more preferable, for the reason of securing and preventing an increase in energy accompanying high pressure.

Also, instead of the forms shown in FIGS. 1, 3 and 4, the form shown in FIG. 5 may be employed.
In FIG. 5, the same reference numerals are assigned to the same configurations as those shown in FIG. In the embodiment of FIG. 5, differences from the embodiments of FIGS. 1, 3, and 4 will be mainly described, and descriptions of the same points as those of the embodiments of FIGS. 1, 3, and 4 will be omitted.

The embodiment of FIG. 5 includes a second bypass line 25 connecting the first bypass line 23 and the first impermeable gas discharge line 14, and
A second inlet gas discharge line 28 branches off from the first impermeable gas discharge line 14 . As shown in FIG. 5, the second bypass line 25 is positioned between the two

connection points

23a and 23b in the first bypass line 23 and between the discharge port 11b and the gas inlet 12a in the first impermeable gas discharge line 14. position (discharge port 11b side of connection point 28a).

According to the embodiment of FIG. 5, as shown in FIG. 5(a), during operation for gas separation (during normal operation), from the first impermeable gas discharge line 14 to the second bypass line 25 and the second inlet Gas is prevented from flowing into the gas discharge line 28 . On the other hand, as shown in FIG. 5(b), the regeneration gas discharged from the gas inlet 12a in the first impermeable gas discharge line 14 during regeneration passes through the line 14 and the second inlet gas discharge line. All of the gas is introduced into the line 28 from the connection point 28a with 28, and is not introduced from the connection point 28a to the impermeable gas discharge port 11b side in the line 14. This switching of the gas flow path is performed by a valve (not shown) arranged at the connection point 28a.

Also, in the first impermeable gas discharge line 14, at a connection point 25a between the line 14 and the second bypass line 25, gas is conducted between the first impermeable gas discharge line 14 and the second bypass line 25 during normal operation. (FIG. 5(a)), during regeneration, the gas from the second bypass line 25 flows from the connecting point 25a with the first impermeable gas discharge line 14 to the impermeable gas discharge port 11b in the line 14. It can be introduced into the first gas separation membrane unit 11 through the passage. This switching of the gas flow path is performed by a valve (not shown) arranged at the connection point 25a.

With the above configuration, as shown in FIG. 5(a), the gas to be separated passes through the same gas flow paths as in FIGS. 1, 3 and 4 during normal operation. That is, the gas to be separated that flows through the supply gas line 6 and is pressurized by the compression means 21 is introduced into the first gas separation membrane unit 11 without passing through the first bypass line 23 and the second bypass line 25. has been made.

On the other hand, as shown in FIG. 5(b), during regeneration, the regeneration gas that flows through the supply gas line 6 and is pressurized by the compression means 21 is heated by the heating means, and flows through the first bypass line 23 and the regeneration gas. It is introduced into the second bypass line 25 and introduced into the second gas separation membrane unit 12 from the impermeable gas outlet 12b through the first bypass line 23 in the same manner as in the embodiment of FIG. 1, the impermeable gas discharge line 14 is connected to the impermeable gas discharge port 11b and introduced into the first gas separation membrane unit 11 .

Of the regeneration gas introduced into the second gas separation membrane unit 12 from the impermeable gas outlet 12b, the gas that has permeated the gas separation membrane is discharged from the permeable gas outlet 12c, and the impermeable gas is discharged from the gas inlet 12a. be done. The impermeable gas discharged from the gas inlet 12 a of the second gas separation membrane unit 12 is taken out of the system through the second inlet gas discharge line 28 . Further, of the regeneration gas introduced into the first gas separation membrane unit 11 from the impermeable gas outlet 11b, the gas that has permeated the gas separation membrane passes through the permeable gas outlet 11c and the first permeable gas in the same manner as in the embodiment of FIG. The gas is discharged out of the system through the gas discharge line 19 . On the other hand, the impermeable gas (regeneration gas) discharged from the gas inlet of the first gas separation membrane unit flows through the first inlet gas discharge line 24 branched from the supply gas line 6 and is discharged outside the system. It is designed to

According to the embodiment of FIG. 5 described above, the regeneration gas can be circulated through the impermeable gas circulation path independently of each of the first gas separation membrane unit 11 and the second gas separation membrane unit 12. 2 In addition to being able to easily prevent organic impurities discharged from the gas separation membrane unit 12 from adhering to the gas separation membranes of the first gas separation membrane unit 11, the first gas separation membrane unit 11 and the second gas separation membrane unit 12 The regeneration gas flow rate suitable for each configuration can be easily set.

Adopting this embodiment is also preferable in that the pressure loss of the regeneration gas can be reduced by shortening the flow path length of the regeneration gas, that is, the compression power of the regeneration gas can be suppressed.

5, the temperature T2' of the regeneration gas at the impermeable gas outlet of the first gas separation membrane unit 11 is used as T2, and the impermeable gas outlet of the second gas separation membrane unit 12 is used as T4. adopt the temperature T4' of the regeneration gas at . In this embodiment, the difference between T2' or T4' and T1 (T2'-T1 or T4'-T1) may be the range of T2-T1 described in the embodiment of FIG. 1, and both are within the above range. is preferred. In the embodiment of FIG. 5, the pressure of the regeneration gas supplied to the first gas separation membrane unit 11 is more preferably 0.1 MPaG or more and 1.4 MPaG or less, and still more preferably 0.2 MPaG or more and 1.2 MPaG or less. Further, in the embodiment of FIG. 5, the pressure of the regeneration gas supplied to the second gas separation membrane unit 12 ensures the pressure for reliably circulating the regeneration gas to the second gas separation membrane unit 12, while maintaining a high pressure. 0.1 MPaG or more and 1.4 MPaG or less is more preferable, and 0.2 MPaG or more and 1.2 MPaG or less is even more preferable, for the reason of preventing an increase in energy associated with quenching.

In the following, we will explain the three-stage gas separation system. In FIG. 6 below, the same components as those shown in FIG. 1 are denoted by the same reference numerals. In the embodiment of FIG. 6, differences from FIG. 1 will be mainly described, and descriptions of the same points as those of the embodiment of FIG. 1 will be omitted. The description of the configuration with the same reference numerals before FIG. 5 can be appropriately applied to this embodiment.

As shown in FIG. 6, the first gas separation membrane unit 11 and the third gas separation membrane unit 13 are connected in series. Specifically, the first gas separation membrane unit 11 and the third gas separation membrane unit 13 are configured such that the permeated gas outlet 11c of the first gas separation membrane unit 11 and the gas inlet 13a of the third gas separation membrane unit 13 are connected by the first permeated gas discharge line 19 . As the gas separation membrane module constituting the third gas separation membrane unit 13, the same modules as those of the first gas separation membrane unit 11 and the second gas separation membrane unit 12 can be adopted.

The compression means 21 pressurizes the raw material mixed gas supplied from the gas source, the permeable gas returned from the second gas separation membrane unit 12 and the impermeable gas returned from the third gas separation membrane unit 13, and compresses the regeneration gas. It is installed for the purpose of pressurizing.

In the third gas separation membrane unit 13, the impermeable gas discharge port 13b is connected to the suction side of the compression means 21 in the supply gas line 6 by the third impermeable gas return line 73. A third permeated gas discharge line 72 is connected to the permeated gas discharge port 13 c of the third gas separation membrane unit 13 .

The gas path during operation for gas separation in the gas separation membrane system 110 of this embodiment having the above configuration (hereinafter also referred to as "normal operation") will be described with reference to FIG. 6(a). A raw material mixed gas to be separated is supplied from a mixed gas source (not shown) through a supply gas line 6 to the first gas separation membrane unit 11 . Prior to supply, the raw material mixed gas is pressurized by the compression means 21 to increase the pressure.

The raw material mixed gas contains at least two different types of gases to be separated: a gas A having a high permeation rate through the gas separation membrane and a gas B having a lower permeability through the gas separation membrane than the gas A. . As shown in FIG. 6( a ), when the raw material mixed gas pressurized by the compression means 21 is supplied to the first gas separation membrane unit 11 , gas It is separated into a permeated gas that has permeated through the separation membrane and an impermeable gas that has not permeated through the gas separation membrane. The impermeable gas discharged from the first gas separation membrane unit 11 is discharged from the impermeable gas discharge port 11b of the first gas separation membrane unit 11, and passes through the first impermeable gas discharge line 14 to the second gas separation membrane unit 12. supplied to On the other hand, in the permeated gas from the first gas separation membrane unit 11, the gas A is concentrated compared to the mixed gas as the raw material, and is discharged from the permeated gas outlet 11c of the first gas separation membrane unit 11, and the first permeated gas It is supplied to the third gas separation membrane unit 13 through the discharge line 19 . The gas introduced into the second gas separation membrane unit 12 is separated into a permeable gas and an impermeable gas by the same unit 12 . In the impermeable gas, the gas B is further concentrated and enriched compared to the gas introduced into the second gas separation membrane unit 12, and the second impermeable gas discharge line 18 is discharged from the impermeable gas discharge port 12b of the same unit 12. It is taken out of the system through On the other hand, the permeated gas is discharged from the permeated gas outlet 12c of the second gas separation membrane unit 12 and is compressed in the supply gas line 6 via the second permeated gas return line 17 connected to the outlet 12c. It is fed back to the suction side of means 21 . Also, the gas introduced into the third gas separation membrane unit 13 is separated into a permeable gas and an impermeable gas by the same unit 13 . In the permeated gas, the gas A is more concentrated and enriched than the gas introduced into the third gas separation membrane unit 13, and the system is discharged from the permeated gas outlet 13c of the unit 13 through the third permeated gas discharge line 72. taken outside. On the other hand, the impermeable gas is discharged from the impermeable gas discharge port 13b of the third gas separation membrane unit 13, and passes through the third impermeable gas return line 73 connected to the discharge port 13b to the supply gas line. 6 is fed back to the suction side of the compression means 21 . The permeable gas and impermeable gas returned through

lines

17 and 73 are mixed with the raw material mixed gas and then compressed by compression means 21 .

After the above normal operation has passed for a certain period of time, the organic impurities in the raw material mixed gas adhere to the first gas separation membrane unit 11, the second gas separation membrane unit 12, and the third gas separation membrane unit 13, so that the first gas The gas permeation performance of the separation membrane unit 11, the second gas separation membrane unit 12 and the third gas separation membrane unit 13 is lowered. In particular, the decrease in permeation performance is generally greater in the order of the first gas separation membrane unit 11, the second gas separation membrane unit 12, and the third gas separation membrane unit 13. At this time, the regeneration gas is heated by the heating means 61 and circulated to at least the first gas separation membrane unit 11 and the second gas separation membrane unit 12, and if necessary, the third gas separation membrane unit 13. , the organic impurities are volatilized and removed from the gas separation membrane unit through which the regeneration gas is circulated, and the permeation performance is recovered.

FIG. 6(b) shows the flow path of the regeneration gas in the gas separation membrane system 110 shown in FIG. As shown in FIGS. 6(a) and 6(b), in the gas separation membrane system 110 shown in FIG. It is similar to the gas flow path of gas. The regeneration gas has been described above. The gas separation membrane constituting the third gas separation membrane unit 13 preferably has a _P'O2 / _P'N2 ratio of 4 to 8 at 40°C, for example. For example, the examples described later use polyimide membranes having separation selectivities within these ranges.

In this embodiment, it is preferable to remove impurities by supplying the regeneration gas to the first gas separation membrane unit 11 at a pressure below a certain level. In the embodiment of FIG. 6, the pressure of the regeneration gas supplied to the first gas separation membrane unit 11 is such that the regeneration gas is supplied to the first gas separation membrane unit, the second gas separation membrane unit, and the third gas separation membrane unit. In order to secure pressure for reliable circulation and prevent an increase in energy due to high pressure, it is more preferably 0.3 MPaG or more and 1.4 MPaG or less, and even more preferably 0.4 MPaG or more and 1.3 MPaG or less. The preferred range of the regeneration gas supply pressure in the second gas separation membrane unit 12 is the same as in the first gas separation membrane unit 11 . Setting the pressure of the third gas separation membrane unit below a certain level increases the differential pressure between the supply pressure and the permeation pressure in the first gas separation membrane unit, and does not suppress permeation in the first gas separation membrane unit. preferable. From this point, the supply pressure of the regeneration gas in the third gas separation membrane unit 13 is more preferably 0.1 MPaG or more and 0.7 MPaG or less, and further preferably 0.2 MPaG or more and 0.5 MPaG or less.

During regeneration, the ratio S2/S1 of the gas supply amount S2 to the second gas separation membrane unit 12 to the gas supply amount S1 to the first gas separation membrane unit 11 is 10% or more. It is preferable in terms of enhancing the effect of simultaneously regenerating the unit 11 to the third gas separation membrane unit 13, more preferably 20% or more, and even more preferably 30% or more. Also, the S2/S1 ratio may be 95% or less, or 90% or less.

During regeneration, the ratio S3/S1 of the gas supply amount S3 to the third gas separation membrane unit 13 to the gas supply amount S1 to the first gas separation membrane unit 11 is 5% or more. It is preferable in terms of enhancing the effect of simultaneously regenerating the unit 11 to the third gas separation membrane unit 13, and more preferably 10% or more. S3/S1 may be 90% or less, or 80% or less.

During regeneration, the ratio S4/S2 of the amount S4 of the gas supplied to the second gas separation membrane unit 12 and returned to the first gas separation membrane unit 11 as the permeating gas of the second gas separation membrane unit 12 is 90%. It is preferably 80% or less in terms of suppressing the load on the compression means 21 and the like due to the return gas. The S4/S2 ratio may be 0%, but when the permeating gas of the second gas separation membrane unit 12 is returned to the first gas separation membrane unit 11, it may be 10% or more, or 20% or more. may

During regeneration, the ratio S5/S3 of the amount S5 of the gas supplied to the third gas separation membrane unit 13 and returned to the first gas separation membrane unit 11 as the impermeable gas of the third gas separation membrane unit 13 is 90. % or less is preferable from the point of suppressing the load on the compression means 21 or the like due to the return gas, and 80% or less is more preferable. Also, the ratio of S5/S3 may be 5% or more, or 10% or more.

At the time of regeneration, the amount of gas supplied to the unit into which the regeneration gas first flows (in this embodiment, the first gas separation membrane unit 11) is the first gas separation membrane unit 11 to the third gas separation membrane unit 13. From the viewpoint of enhancing the effect of simultaneous regeneration, it is preferably 10% or more, more preferably 20% or more, of the normal operation.

In the three-stage system, during regeneration, the ratio G2/G1 of the gas supply pressure G2 to the second gas separation membrane unit 12 to the gas supply pressure G1 to the first gas separation membrane unit 11 is 10% or more. is preferable from the point of enhancing the effect of simultaneously regenerating the first gas separation membrane unit 11 to the third gas separation membrane unit 13, more preferably 20% or more, and even more preferably 50% or more. G2/G1 may be 98% or less, or 95% or less.

During regeneration, the ratio G3/G1 of the gas supply pressure G3 to the third gas separation membrane unit 13 to the gas supply pressure G1 to the first gas separation membrane unit 11 is 10% or more. It is preferable in terms of enhancing the effect of simultaneously regenerating the membrane unit 11 to the third gas separation membrane unit 13, and more preferably 20% or more. G3/G1 may be 50% or less, or 40% or less.

From the viewpoint of simultaneously reproducing three units, the playback time in this method is preferably 10 minutes or longer, and more preferably 20 minutes or longer.

In this embodiment, as shown in FIG. 6(b), the regeneration gas heated by the heating means 61 can immediately flow into the first gas separation membrane unit 11, and the gas separation membranes of the first gas separation membrane unit 11 can be heated. The organic impurities adhering to the gas separation membrane are volatilized by contacting the regeneration gas. Among the volatilized organic impurities, there are some that are difficult to permeate through the gas separation membrane. Therefore, a certain proportion of the organic impurity volatiles adhering to the gas separation membranes of the first gas separation membrane unit 11 is introduced into the second gas separation membrane unit 12 along with the impermeable gas. The impermeable gas containing organic impurity volatiles discharged from the first gas separation membrane unit 11 contacts the gas separation membrane of the second gas separation membrane unit 12 in a heated state, and the second gas separation membrane unit 12 volatilize the organic impurities adhering to the gas separation membrane. A certain amount of these organic impurities are accompanied by the impermeable gas in the second gas separation membrane unit 12 and are removed through the second impermeable gas discharge line 18 . Also, organic impurities adhering to the gas separation membranes of the second gas separation membrane unit 12 may volatilize and be included in the permeated gas of the second gas separation membrane unit 12 .

The heated regeneration gas is introduced into the third gas separation membrane unit 13 as the permeating gas of the first gas separation membrane unit 11, and in a heated state, contacts the gas separation membranes of the third gas separation membrane unit 13, Organic impurities adhering to the gas separation membranes of the third gas separation membrane unit 13 are volatilized. A certain amount of organic impurities are accompanied by the permeated gas of the third gas separation membrane unit 13 and removed through the third permeated gas discharge line 72 . Also, organic impurities adhering to the gas separation membranes of the third gas separation membrane unit 13 may volatilize and be included in the impermeable gas of the third gas separation membrane unit 13 .

In order to prevent organic impurities in the regeneration gas from the first gas separation membrane unit 11 from condensing in the gas separation membranes of the second gas separation membrane unit 12 and/or the third gas separation membrane unit 13, the second With the gas separation membranes of the second gas separation membrane unit 12 and/or the third gas separation membrane unit 13 heated, the regeneration gas from the first gas separation membrane unit 11 is supplied to the second gas separation membrane unit 12 and/or the third Although it may be introduced into the gas separation membrane unit 13, the present invention allows restoration of the permeability of the gas separation membrane without such preheating of the separation membrane. In addition, a filter or the like (not shown) is provided in the first impermeable gas discharge line 14 and/or the first permeable gas discharge line 19 to regenerate volatile organic impurities adhering to the gas separation membranes of the first gas separation membrane unit 11. The gas for regeneration may be removed from the gas for regeneration, and the treated gas for regeneration may be supplied to the second gas separation membrane unit 12 and/or the third gas separation membrane unit 13 . Similarly, a filter (not shown) is provided in the

return lines

17 and 73 so that the permeating gas of the second gas separation membrane unit 12 and the non-permeating gas of the third gas separation membrane unit 13 are removed from these gases before returning to the supply gas line 6. Organic impurities may be removed.

As described above, in the embodiment shown in FIG. 6, the separation membranes of the first gas separation membrane unit 11, the second gas separation membrane unit 12, and the third gas separation membrane unit 13 can be regenerated without installing a regeneration line. It is possible to plan

As shown in FIG. 6B, the temperature T6 of the regeneration gas when introduced into the third gas separation membrane unit 13 is the same as that of the third gas separation membrane unit during operation for gas separation (during normal operation). The difference (T6-T5) from the temperature T5 of the gas to be separated introduced into the gas inlet 13 is preferably 20°C or higher and 80°C or lower, more preferably 30°C or higher and 80°C or lower. T5 is usually preferably 5°C or higher and 60°C or lower, and T6 is preferably 40°C or higher and 120°C or lower. Likewise, T6-T1, T6-T3, T2-T5, and T4-T5 are each preferably 20° C. or higher and 80° C. or lower, and more preferably 30° C. or higher and 80° C. or lower. In this embodiment, T6 is the temperature T6 of the regeneration gas when it is introduced into the gas inlet of the third gas separation membrane unit 13 .

As an advantage of this embodiment, in addition to the fact that it is not necessary to install a regeneration line, the first gas separation membrane unit, the second gas separation membrane unit, and the third gas separation membrane unit can be removed from the gas separation membrane system. Since the high-temperature gas for regeneration can be shared by the first gas separation membrane unit, the second gas separation membrane unit, and the third gas separation membrane unit compared to the case of regenerating individually, it is necessary to raise the temperature of the regeneration gas. Another advantage is that the amount of heat required by the heating means can be suppressed.

Next, another embodiment of the present invention will be described based on FIG. In FIG. 7, the same reference numerals are assigned to the same configurations as those shown before FIG. In the embodiment of FIG. 7, differences from the embodiment before FIG. 6 will be mainly described, and description of the same points as in FIG. 6 will be omitted. The description of the configuration with the same reference numerals before FIG. 5 can be appropriately applied to this embodiment.

In the embodiment of FIG. 7, a second permeated gas discharge line 22 branched from the second permeated gas return line 17 is provided, and when the regeneration gas is introduced into the second gas separation membrane unit 12, the second gas separation membrane unit 12 The permeated gas discharged from is discharged outside the system through the second permeated gas discharge line 22 without returning to the supply gas line 6, and the third non-permeated gas branched from the third non-permeated gas return line 73 A permeated gas discharge line 74 is provided, and the impermeable gas of the third gas separation membrane unit 13 into which the regeneration gas is introduced is discharged out of the system through the third impermeable gas discharge line 74 without returning to the supply gas line 6. It is made to be done. It should be noted that the term "outside the system" means that the gas is taken out without being introduced into any of the first gas separation membrane unit 11, the second gas separation membrane unit 12, and the third gas separation membrane unit 13.

As shown in FIG. 7, the second permeated gas discharge line 22 is located at a position 22a (also referred to as a "branch point 22a") in the second permeated gas return line 17 on the way from the permeated gas discharge port 12c to the supply gas line 6. ) branched from the second permeated gas return line 17 . During operation for gas separation, the gas in the second permeated gas return line 17 does not flow into the second permeated gas discharge line 22 (FIG. 7(a)).
On the other hand, during regeneration, the second permeated gas return line 17 and the second permeated gas discharge line 22 are connected at the branch point 22a, and the permeated gas discharged from the second gas separation membrane unit 12 is discharged through the second permeated gas discharge line 22. , so that it does not flow to the supply gas line 6 side of the branch point 22a in the line 17 (FIG. 7(b)). Such switching is performed using a valve (not shown) at the branch point 22a. The second permeated gas discharge line 22 connects the outside of the system and the middle position of the second permeated gas return line 17 .

As shown in FIG. 7, the third impermeable gas discharge line 74 is located at a position 74a (hereinafter referred to as "branch point 74a ”). During operation for gas separation, the gas in the third non-permeable gas return line 73 does not flow into the third non-permeable gas discharge line 74 (Fig. 7(a)). On the other hand, during regeneration, the third impermeable gas return line 73 and the third impermeable gas discharge line 74 are electrically connected, and the impermeable gas discharged from the third gas separation membrane unit 13 is transferred to the third It is introduced into the impermeable gas discharge line 74, and does not flow from the branch point 74a of the third impermeable gas return line 73 to the supply gas line 6 side (FIG. 7(b)). Such switching is performed using a valve (not shown) at the branch point 74a. A third impermeable gas discharge line 74 connects the outside of the system and a midpoint of the third impermeable gas return line 73 .

As described above, the permeated gas from the second gas separation membrane unit 12 does not flow through the second permeated gas discharge line 22 during operation for gas separation as shown in FIG. It is returned to the feed gas line 6 through the return line 17 . As shown in FIG. 7(a), the flow path of the separation target gas during operation for gas separation is the same as in the embodiment of FIG. On the other hand, as shown in FIG. 7B, during regeneration, the permeated gas from the second gas separation membrane unit 12 is discharged outside the system without returning to the supply gas line 6 through the second permeated gas discharge line 22. It is made like this.

As described above, the impermeable gas from the third gas separation membrane unit 13 does not flow through the third impermeable gas discharge line 74 during operation for gas separation as shown in FIG. It is returned to feed gas line 6 through impermeable gas return line 73 . On the other hand, as shown in FIG. 7B, during regeneration, the impermeable gas from the third gas separation membrane unit 13 does not return to the supply gas line 6 through the third impermeable gas discharge line 74, but exits the system. It is made to be discharged.

According to the embodiment of FIG. 7 described above, during regeneration, the organic matter that has volatilized from the state attached to the gas separation membrane of the second gas separation membrane unit 12 and is included in the permeated gas of the second gas separation membrane unit 12 Impurities can be immediately removed out of the system through the second permeate gas discharge line 22 without being returned to the feed gas line 6 .
Similarly, during regeneration, the organic impurities that have volatilized from the gas separation membranes of the third gas separation membrane unit 13 and are included in the impermeable gas of the third gas separation membrane unit 13 are removed from the supply gas line. 6, it can be immediately removed out of the system through the third impermeable gas discharge line 74.
Therefore, in this embodiment, the first gas separation membrane unit 11 and the second gas separation membrane unit 12 are more efficiently operated while reducing the regeneration time, the compressor power required for regeneration, etc., as compared with the embodiment of FIG. And it is preferable in that regeneration of the gas separation membrane in the third gas separation membrane unit 13 can be achieved.

Further, by adopting this embodiment, the second permeated gas return line 17 and the third non-permeated gas return to the supply gas line 6 and the filter (not shown) interposed between the compression means and the heating means. It is also preferable in terms of reducing the load of the impurity-containing regeneration gas returned via the line 73 .

For example, when regenerating the second gas separation membrane unit 12, if there is a high tendency for organic impurities to be contained in the gas permeating the gas separation membrane of the second gas separation membrane unit 12, the advantage of adopting the line 22 increases. Whether the organic impurities are contained in the permeating gas of the gas separation membrane of the second gas separation membrane unit 12 or in the impermeable gas depends on the type of raw material mixed gas during operation for gas separation and the regeneration gas. type, the temperature of the regeneration gas, and the type of impurities. As a regeneration gas having a line 22 as shown in FIG. 7, there is a high tendency for organic impurities to be contained in the gas permeating the gas separation membrane of the second gas separation membrane unit 12 during regeneration.

In addition, in the embodiments after FIG. 7, preferable temperatures of T5 to T6 are the same as those in the embodiment of FIG. The preferred ranges of T6-T5, T6-T1, T6-T3, T2-T5, and T4-T5 are also the same as in the embodiment of FIG. In addition, in the embodiment of FIG. 7, the pressure of the regeneration gas supplied to the first gas separation membrane unit 11 is the same as the pressure for regeneration to the first gas separation membrane unit, the second gas separation membrane unit, and the third gas separation membrane unit. In order to secure a pressure for reliably circulating gas and to prevent an increase in energy due to high pressure, the pressure is more preferably 0.3 MPaG or more and 1.4 MPaG or less, and further preferably 0.4 MPaG or more and 1.3 MPaG or less.

Furthermore, instead of the forms shown in FIGS. 6 and 7, the form shown in FIG. 8 is also available. In FIG. 8, the same components as those shown in FIG. 7 are denoted by the same reference numerals. In the embodiment of FIG. 8, differences from the embodiments of FIGS. 6 and 7 will be mainly described, and descriptions of the same points as those of FIGS. 6 and 7 will be omitted. The description of the configuration with the same reference numerals before FIG. 5 can be appropriately applied to this embodiment.

The embodiment of FIG. 8 has a first bypass line 23 and a first inlet gas discharge line 24 in addition to the second permeated gas discharge line 22 described above.
The first bypass line 23 connects the position of the heating means 61 in the supply gas line 6 on the first gas separation membrane unit 11 side and the second impermeable gas discharge line 18 . The first inlet gas discharge line 24 branches off from the supply gas line 6 on the first gas separation membrane unit 11 side of the connection point 23 a of the first bypass line 23 of the supply gas line 6 . The first inlet gas discharge line 24 is a line that connects the outside of the system and the supply gas line 6 .

According to the embodiment of FIG. 8, as shown in FIG. 8(a), during operation for gas separation (during normal operation), from the supply gas line 6, the first bypass line 23 and the first inlet gas discharge line 24 The raw material mixed gas is prevented from flowing into. On the other hand, as shown in FIG. 8B, during regeneration, the regeneration gas is flowed from the supply gas line 6 into the first bypass line 23, and the supply gas line 6 is located at the first bypass line 23 from the connection point 23a. 1 Gas separation membrane unit 11 side is prevented from flowing gas. This switching of the gas flow path is performed by a valve (not shown) arranged at the connection point 23 a between the first bypass line 23 and the supply gas line 6 .

Further, at the branch point (connecting point) 24a of the first inlet gas discharge line 24 from the line 6 in the supply gas line 6, as described above, gas does not flow from the supply gas line 6 during normal operation (Fig. 8 ( a)) During regeneration, gas is introduced into the first inlet gas discharge line 24 from the first gas separation membrane unit 11 side of the branch point 24a in the supply gas line 6, and is introduced from the branch point 24a in the supply gas line 6 to the branch point 23a. It is made so that gas does not flow to the side. This switching of the gas flow path is performed by a valve (not shown) arranged at a branch point 24 a of the first inlet gas discharge line 24 from the supply gas line 6 .

With the above configuration, as shown in FIG. 8(a), the gas to be separated passes through the same gas flow path as in FIGS. 6 and 7 during normal operation. Therefore, the gas to be separated that flows through the supply gas line 6 and is pressurized by the compression means 21 is introduced into the first gas separation membrane unit 11 without passing through the first bypass line 23 .

On the other hand, as shown in FIG. 8(b), during regeneration, the regeneration gas that flows through the supply gas line 6 and is pressurized by the compression means 21 is heated by the heating means to the first bypass line 23. After being introduced into the second impermeable gas discharge line 18 through the second gas separation membrane unit 12 side of the connection point 23b of the second impermeable gas discharge line 18 with the first bypass line 23, the gas during normal operation It circulates in the direction opposite to the direction of flow, and is introduced into the second gas separation membrane unit 12 from the impermeable gas discharge port 12b.

Of the regeneration gas introduced from the impermeable gas outlet 12b of the second gas separation membrane unit 12, the gas that has permeated the gas separation membrane is discharged from the permeable gas outlet 12c, and the impermeable gas is discharged from the gas inlet 12a. be done. The impermeable gas discharged from the gas inlet 12 a of the second gas separation membrane unit 12 is introduced into the first gas separation membrane unit 11 from the impermeable gas discharge port 11 b through the first impermeable gas discharge line 14 . Of the impermeable gas (regenerating gas) introduced into the first gas separation membrane unit 11, the permeable gas is introduced into the third gas separation membrane unit 13 and thereafter flows in the same manner as in FIG. On the other hand, impermeable gas is discharged from the gas inlet of the first gas separation membrane unit. The impermeable gas (regenerating gas) discharged from the gas inlet 11a of the first gas separation membrane unit is introduced into the first inlet gas discharge line 24 branched from the supply gas line 6, and the first inlet gas is discharged. It circulates through the line 24 and is discharged outside the system.

According to the embodiment of FIG. 8 above, by causing the heated regeneration gas to flow backward through the impermeable gas circulation spaces of the gas separation membrane modules that constitute the first gas separation membrane unit 11 and the second gas separation membrane unit 12, There is an advantage that organic impurities adhering to the impermeable side of the gas separation membrane in the gas separation membrane module can be effectively removed, which is particularly advantageous for regeneration of the second gas separation membrane unit 12 . The organic impurity volatiles derived from the gas separation membrane of the unit 12 contained in the impermeable gas of the second gas separation membrane unit 12 came into contact with the gas separation membrane of the first gas separation membrane unit 11. In order to prevent condensation, the regeneration gas may be passed through the first gas separation membrane unit 11 while the gas separation membranes of the first gas separation membrane unit 11 are heated.

Further, by adopting this embodiment, when the degree of contamination of the first gas separation membrane unit 11 is higher than that of the second gas separation membrane unit 12, the gas discharged from the first gas separation membrane unit 11 during regeneration It is possible to easily prevent the impurities from adhering to the gas separation membrane of the second gas separation membrane unit 12, which has a relatively low degree of contamination, and the second impermeable gas discharge line 18 is the product gas during normal operation. When connected to a downstream system, such as a supply system, it is also preferred in that it does not contaminate the downstream system with the impurity-containing regeneration gas.

In the embodiment of FIG. 8, the temperature T2 of the regeneration gas introduced into the first gas separation membrane unit 11 is the temperature T2′ of the regeneration gas introduced into the impermeable gas outlet of the first gas separation membrane unit 11. to adopt. As the temperature T4 of the regeneration gas introduced into the second gas separation membrane unit 12, the temperature T4' of the regeneration gas introduced into the impermeable gas outlet of the second gas separation membrane unit 12 is employed. 8, the temperature of the regeneration gas when introduced into the third gas separation membrane unit 13 is the temperature of the regeneration gas when introduced into the gas inlet of the third gas separation membrane unit 13. to adopt. In the embodiment of FIG. 8, the pressure of the regeneration gas supplied to the second gas separation membrane unit 12 is such that the regeneration gas is supplied to the second gas separation membrane unit, the first gas separation membrane unit, and the third gas separation membrane unit. In order to secure pressure for reliable circulation and prevent an increase in energy due to high pressure, it is more preferably 0.4 MPaG or more and 1.4 MPaG or less, and still more preferably 0.5 MPaG or more and 1.3 MPaG or less.

Further, instead of the forms shown in FIGS. 6, 7 and 8, the form shown in FIG. 9 may be adopted.
In FIG. 9, the same components as those shown in FIG. 8 are denoted by the same reference numerals. In the embodiment of FIG. 9, differences from the embodiments of FIGS. 6, 7, and 8 will be mainly described, and descriptions of the same points as those of FIGS. 6, 7, and 8 will be omitted. The description of the configuration with the same reference numerals before FIG. 5 can be appropriately applied to this embodiment.

In the embodiment of FIG. 9, a second bypass line 25 connecting the first bypass line 23 and the first impermeable gas discharge line 14 is provided, and a second inlet gas discharge line branching from the first impermeable gas discharge line 14 is provided. 28.

According to the embodiment of FIG. 9, as shown in FIG. 9(a), during operation for gas separation (during normal operation), from the first impermeable gas discharge line 14 to the second bypass line 25 and the second inlet Gas is prevented from flowing into the gas discharge line 28 . On the other hand, as shown in FIG. 9B, in the first impermeable gas discharge line 14 during regeneration, all the gas from the gas inlet 12a is introduced from the connection point 28a to the second inlet gas discharge line 28, and the connection point 28a is not introduced into the impermeable gas discharge port 11b side. This switching of the gas flow path is performed by a valve (not shown) arranged at the connection point 28a.

Further, at the connection point 25a of the first impermeable gas discharge line 14 with the second bypass line 25, gas is not conducted between the first impermeable gas discharge line 14 and the second bypass line 25 during normal operation. (FIG. 9(a)) During regeneration, the gas from the second bypass line 25 passes through the passage from the connection point 25a of the first non-permeable gas discharge line 14 to the non-permeable gas discharge port 11b to the first gas separation membrane unit. 11 can be introduced. This switching of the gas flow path is performed by a valve (not shown) arranged at the connection point 25a.

With the above configuration, as shown in FIG. 9(a), during normal operation, the gas to be separated passes through the same gas flow paths as in FIGS. 6, 7 and 8. Therefore, the gas to be separated that flows through the supply gas line 6 and is pressurized by the compression means 21 is introduced into the first gas separation membrane unit 11 without passing through the first bypass line 23 and the second bypass line 25. has been made.

On the other hand, as shown in FIG. 9(b), during regeneration, the regeneration gas that flows through the supply gas line 6 and is pressurized by the compression means 21 is heated by the heating means, and flows through the first bypass line 23 and the regeneration gas. It is introduced into the second bypass line 25 and is introduced into the second gas separation membrane unit 12 through the first bypass line 23 from the non-permeable gas outlet 12b as in the embodiment of FIG. 1 from the connection point 25 a with the impermeable gas discharge line 14 to the impermeable gas discharge port 11 b and introduced into the first gas separation membrane unit 11 .

During regeneration, of the regeneration gas introduced from the impermeable gas outlet 12b of the second gas separation membrane unit 12, the gas that has permeated the gas separation membrane is discharged from the permeable gas outlet 12c, and the impermeable gas is discharged from the gas inlet. 12a is discharged. The impermeable gas discharged from the gas inlet 12 a of the second gas separation membrane unit 12 is taken out of the system through the second inlet gas discharge line 28 . Further, of the regeneration gas introduced into the first gas separation membrane unit 11 from the impermeable gas outlet 11b, the gas that has permeated the gas separation membrane passes through the permeable gas outlet 11c and the first permeable gas outlet 11c in the same manner as in the embodiment of FIG. It is introduced into the third gas separation membrane unit 13 through the gas discharge line 19 . On the other hand, the impermeable gas (regeneration gas) discharged from the gas inlet of the first gas separation membrane unit is introduced into the first inlet gas discharge line 24 branched from the supply gas line 6, and the first inlet gas It circulates through the discharge line 24 and is discharged out of the system. The flow path of the gas reaching the third gas separation membrane unit 13 is the same as in the embodiments of FIGS. 7 and 8. FIG.

According to the embodiment of FIG. 9 described above, the regeneration gas can be circulated through the impermeable gas circulation path independently of each of the first gas separation membrane unit 11 and the second gas separation membrane unit 12. 2 In addition to being able to easily prevent organic impurities discharged from the gas separation membrane unit 12 from adhering to the gas separation membranes of the first gas separation membrane unit 11, the first gas separation membrane unit 11 and the second gas separation membrane unit 12 The regeneration gas flow rate suitable for each configuration can be easily set. 8, the regeneration gas that does not pass through the second gas separation membrane unit 12 can be introduced into the third gas separation membrane unit 13, and the regeneration gas introduced into the third gas separation membrane unit 13 can be made with less organic impurities.

In the embodiment of FIG. 9, the temperature T2′ of the regeneration gas at the impermeable gas outlet of the first gas separation membrane unit 11 or the temperature T4 of the regeneration gas at the impermeable gas outlet of the second gas separation membrane unit 12 It is sufficient that the difference T2'-T1 or T4'-T1 between T' and T1 is in the range (T2-T1) described in FIG. 1 above, and both are preferably in the above range. In the embodiment of FIG. 9, the pressure of the regeneration gas supplied to the first gas separation membrane unit 11 is more preferably 0.3 MPaG or more and 1.4 MPaG or less, still more preferably 0.4 MPaG or more and 1.3 MPaG or less. Further, in the embodiment of FIG. 9, the pressure of the regeneration gas supplied to the second gas separation membrane unit 12 ensures the pressure for reliably circulating the regeneration gas to the second gas separation membrane unit 12, while maintaining a high pressure. 0.1 MPaG or more and 1.4 MPaG or less is more preferable, and 0.2 MPaG or more and 1.3 MPaG or less is still more preferable for the reason of preventing an increase in energy associated with quenching.

10 may be adopted in place of the forms shown in FIGS. 6 and 7 to 9. FIG.
In FIG. 10, the same components as those shown in FIG. 9 are given the same reference numerals. In the embodiment of FIG. 10, differences from the embodiments of FIGS. 6 and 7 to 9 will be mainly described, and descriptions of the same points as those of FIGS. 6 and 7 to 9 will be omitted. The description of the configuration with the same reference numerals before FIG. 5 can be appropriately applied to this embodiment.

In the embodiment of FIG. 10, a third unit avoidance line 76 branched from the first permeated gas discharge line 19 is provided, and the permeated gas discharged from the first gas separation membrane unit 11 is discharged from the third gas separation membrane unit 13 during regeneration. It is possible to output to the outside of the system without going through

As shown in FIG. 10(a), the third unit avoidance line 76 branches off from a branch point 19a at a position between the permeated gas discharge port 11c and the gas inlet 13a in the first permeated gas discharge line 19, and exits the system. It is connected. According to the embodiment of FIG. 10, gas is prevented from flowing into the third unit avoidance line 76 from the permeated gas discharge line 19 during operation for gas separation (during normal operation). On the other hand, as shown in FIG. 10(b), in the first permeated gas discharge line 19 during regeneration, all the gas discharged from the permeated gas discharge port 11c is introduced from the branch point 19a into the third unit avoidance line 76. It is designed not to be introduced into the 3-gas separation membrane unit 13 . This switching of the gas flow path is performed by a valve (not shown) arranged at the branch point 19a.

According to the embodiment of FIG. 10 described above, the regeneration gas permeated in the first gas separation membrane unit 11 is not allowed to flow through the third gas separation membrane unit 13, so that the gas contained in the permeated gas of the first gas separation membrane unit 11 is It is possible to reliably prevent the organic impurities contained in the permeating gas from adhering to the gas separation membranes of the third gas separation membrane unit 13 .

11 may be adopted in place of the forms shown in FIGS. 6 and 7 to 10. FIG.
In FIG. 11, the same reference numerals are assigned to the same configurations as those shown in FIG. In the embodiment of FIG. 11, differences from the embodiments of FIGS. 6 and 7 to 10 will be mainly described, and descriptions of the same points as those of FIGS. 6 and 7 to 10 will be omitted. The description of the configuration with the same reference numerals before FIG. 5 can be appropriately applied to this embodiment.

The embodiment of FIG. 11 includes a third bypass line 77 connecting the first bypass line 23 and the third impermeable gas return line 73, and a third inlet gas discharge line 78 branching from the first permeated gas discharge line 19, respectively. The third inlet gas discharge line 78 branches off from the first permeated gas discharge line 19 on the third gas separation membrane unit 13 side of the third unit avoidance line 76 .

As shown in FIG. 11(a), the third bypass line 77 branches from the branch point 23c of the first bypass line 23, and is connected to the third impermeable gas return line 73 at the connection point 73a in FIG. . The connection point 23 c of the first bypass line 23 is located between the connection point 25 b with the second bypass line 25 and the connection point 23 b between the first bypass line 23 and the second impermeable gas discharge line 18 . The connection point 73a is located between a branch point 74a, which is a connection point of the third impermeable gas return line 73 with the third impermeable gas discharge line 74, and the impermeable gas discharge port 13b. As shown in FIG. 11(a), gas is prevented from flowing from the third impermeable gas return line 73 to the third bypass line 77 during operation for gas separation (during normal operation). On the other hand, as shown in FIG. 11(b), gas is introduced from the first bypass line 23 into the third bypass line 77 during regeneration, and the gas in the third bypass line 77 flows from the connection point 73a to the impermeable gas return line 73. All of them are switched to be introduced into the impermeable gas outlet 13 b of the third gas separation membrane unit 13 . This switching of the gas flow path is performed by a valve (not shown) arranged at the connection point 73a.

According to the embodiment of FIG. 11, as shown in FIG. 11(a), during operation for gas separation (during normal operation), from the first permeated gas discharge line 19 to the third unit avoidance line 76 and the third inlet Gas is prevented from flowing into the gas discharge line 78 . On the other hand, as shown in FIG. 11(b), in the first permeated gas discharge line 19 during regeneration, the gas from the gas inlet 13a flows into the line 78 from the connection point 78a between the line 19 and the third inlet gas discharge line 78. All the permeated gas is introduced through the first permeated gas discharge line 19 so as not to be introduced from the connection point 78a to the permeated gas discharge port 11c side. This switching of the gas flow path is performed by a valve (not shown) arranged at the connection point 78a.

According to the embodiment of FIG. 11 described above, during normal operation, the gas to be separated passes through the same gas flow paths as in FIGS.
On the other hand, during regeneration, the regeneration gas heated by the heating means 61 is introduced into the first bypass line 23, introduced into the third bypass line 77 from the connecting point 23c, and then returned to the third impermeable gas from the connecting point 73a. The gas is introduced into the third gas separation membrane unit 13 from the impermeable gas discharge port 13b through the line 73 in a reverse direction to the gas flow direction during normal operation, and from the gas inlet 13a of the third gas separation membrane unit 13. The regeneration gas, which is the discharged non-permeable gas, is discharged out of the system through the third inlet gas discharge line 78 .

11, in addition to the first gas separation membrane unit 11 and the second gas separation membrane unit 12, the third gas separation membrane unit 13 also independently supplies the regeneration gas to the impermeable gas flow path. Since it can be circulated, organic impurities discharged from the first gas separation membrane unit 11 during regeneration can be easily prevented from adhering to the gas separation membrane of the third gas separation membrane unit 13, and the first gas separation membrane It is possible to easily set regeneration gas flow rates suitable for the configurations of the unit 11, the second gas separation membrane unit 12, and the third gas separation membrane unit 13, respectively.
As the temperature T6 of the regeneration gas introduced into the third gas separation membrane unit 13, the temperature T6' of the regeneration gas introduced into the impermeable gas outlet of the third gas separation membrane unit 13 is employed.

Further, by adopting this embodiment, the heated regeneration gas is caused to flow back through the non-permeable gas circulation space of the gas separation membrane module constituting the third gas separation membrane unit 13, so that the gas separation membrane in the gas separation membrane module It is also preferable in that organic impurities adhering to the non-permeable side can be effectively removed.

Further, by adopting this embodiment, it is not necessary to ensure the pressure for circulating the regeneration gas to the third gas separation membrane unit 13 via the first gas separation membrane unit 11, so the first gas separation membrane It is also preferable in that the compression energy of the regeneration gas to be supplied to the unit can be reduced.

As described above, with the gas separation membrane system of the present invention, the permeability of the gas separation membranes can be efficiently and easily regenerated without removing the gas separation membrane module from the state in which three gas separation membrane units are combined. .

The present invention will be described in more detail below with reference to examples. However, the scope of the invention is not limited to such examples.

[Example 1]
(1) Gas Separation Using the system 10 shown in FIG. 1, a raw material mixed gas (biogas) in which the highly permeable gas A is carbon dioxide and the low permeable gas B is methane was separated. As the first gas separation membrane unit 11, one module ( _P'O2 / _P'N2 at 40°C of 4 to 8) using a hollow fiber membrane made of polyimide was used. As the second gas separation membrane unit 12, one module using a hollow fiber membrane made of polyimide ( _P'O2 / _P'N2 at 40°C is 4 to 8) was used. A compressor was used as the compression means 21 . An electric heater was used as the heating means 61 . The composition of the raw material mixed gas was approximately 40 mol % of gas A and approximately 60 mol % of gas B.
The supply flow rate of the raw material mixed gas to the supply gas line 6 (supply flow rate to the system) was 135 Nm ³ /h. The system was operated at a pressure of 1.2 MPaG and a temperature of 25° C. at the gas inlet of the first gas separation membrane unit 11 via a compressor and an electric heater. In the initial steady state, the methane concentration in the impermeable gas of the second gas separation membrane unit 12, which represents system performance, was 98.0%. The methane concentration in the impermeable gas of the two-gas separation membrane unit 12 decreased to 90.9%. As a filter (not shown) between the compressing means 21 and the heating means 61, an activated carbon filter was used.
(2) Regeneration Air was introduced into the supply gas line 6 as a regeneration gas. The regeneration gas (compressed air) pressurized to 0.7 MPaG by the compression means 21 was heated to 100° C. by an electric heater and supplied. The amount of regeneration gas supplied to the first gas separation membrane unit 11 was 115 Nm ³ /h, the amount of supply to the second gas separation membrane unit 12 was 100 Nm ³ /h, and the regeneration gas to the second gas separation membrane unit 12 was 100 Nm 3 /h. The supply pressure was 0.56 MPaG, and the amount S4 of the permeated gas flowing back from the permeated gas outlet of the second gas separation membrane unit 12 to the first gas separation membrane unit 11 was 40 Nm ³ /h. The required heat of the electric heater was 53 kW. The regeneration treatment was carried out for 3 hours.
(3) Reoperation When the feed air was supplied to the supply gas line 6 at a supply flow rate of 135 Nm ³ /h, the methane concentration in the impermeable gas of the second gas separation membrane unit 12 recovered to 97.4%.

[Comparative Example 1]
(1) and (3) were carried out in the same manner as in Example 1. The first gas separation membrane unit 11 and the second gas separation membrane unit 12 were removed from the gas separation membrane system and individually regenerated. The supply temperature, supply pressure, and supply flow rate of the regeneration gas (compressed air) to each gas separation membrane unit were the same as in Example 1. The heat amount of the electric heater required for regeneration of the first gas separation membrane unit 11 was 53 kW, and the heat amount of the electric heater required for regeneration of the second gas separation membrane unit 12 was 38 kW, for a total of 91 kW.

Tables 1 and 2 summarize the operating conditions and regeneration results of the above examples and comparative examples.

[Example 2]
(1) Gas Separation The procedure was carried out in the same manner as in Example 1, except that the system shown in FIG. 3 was used.
(2) Regeneration The introduction amount of air was set so that the supply flow rate to the second gas separation membrane unit 12 was the same as in the first embodiment. The reflux amount S4 was 0 Nm ³ /h. The regeneration treatment was carried out for 3 hours. The required heat of the electric heater was 52 kW.
(3) Reoperation When the feed air was supplied to the supply gas line 6 at a supply flow rate of 135 Nm ³ /h, the methane concentration in the impermeable gas of the second gas separation membrane unit 12 recovered to 97.4%.

Tables 3 and 4 summarize the operating conditions and regeneration conditions of Example 2 above. In Example 2 using the system of FIG. 3, since there is no recycle gas during regeneration, the oxygen concentration of the air supplied to the first gas separation membrane unit 11 does not increase, and Example 1 using the system of FIG. Compared to , the ratio of the permeating gas in the first gas separation membrane unit 11 can be suppressed. As a result, the amount of air supplied to the first gas separation membrane unit 11 can be reduced by 2% compared to the configuration of FIG. did it.
The reason why the regeneration efficiency is the same between Example 1 and Example 2 is that even if impurities are present in the permeating gas of the second unit and the non-permeating gas of the third unit, the compression means 21 and the heating This is because impurities are removed by a filter (not shown) positioned between the means 61 (the same applies to Examples 3 and 4 below).

With the gas separation membrane system of the present invention, the permeability of the gas separation membrane can be efficiently and easily regenerated without removing the gas separation membrane module from the state in which two gas separation membrane units are combined.

[Example 3]
(1) Gas Separation Using the system 10 shown in FIG. 6, a raw material mixed gas in which the high-permeability gas A is carbon dioxide and the low-permeability gas B is methane was separated. As the first gas separation membrane unit 11 ( _P'O2 / _P'N2 at 40°C is 4 to 8), one module using a hollow fiber membrane made of polyimide was used. As the second gas separation membrane unit 12, one module using a hollow fiber membrane made of polyimide ( _P'O2 / _P'N2 at 40°C is 4 to 8) was used. As the third gas separation membrane unit 13, one module using a hollow fiber membrane made of polyimide ( _P'O2 / _P'N2 at 40°C is 4 to 8) was used. A compressor was used as the compression means 21 . An electric heater was used as the heating means 61 . The composition of the raw material mixed gas was approximately 40 mol % of gas A and approximately 60 mol % of gas B. The temperature of the raw material mixed gas was 25°C.
The supply flow rate of the raw material mixed gas to the supply gas line 6 (supply flow rate to the system) was 94 Nm ³ /h. The system was operated at a pressure of 1.2 MPaG and a temperature of 25° C. at the gas inlet of the first gas separation membrane unit 11 via a compressor and an electric heater. In the initial steady state, the methane concentration in the impermeable gas of the second gas separation membrane unit 12, which represents system performance, was 98.0%. The methane concentration in the impermeable gas of the two-gas separation membrane unit 12 decreased to 90.8%. As a filter (not shown) between the compressing means 21 and the heating means 61, an activated carbon filter was used.
(2) Regeneration Air was introduced into the supply gas line 6 as a regeneration gas. The regeneration gas (compressed air) pressurized to 1.0 MPaG by the compression means 21 was heated to 100° C. by an electric heater and supplied. The supply amount of the regeneration gas to the first gas separation membrane unit 11 is 115 Nm ³ /h, the supply amount to the second gas separation membrane unit 12 is 100 Nm ³ /h, and the supply amount to the third gas separation membrane unit 13 is It was 15 Nm ³ /h. The required heat quantity of the electric heater was 73 kW. The regeneration treatment was carried out for 3 hours. The amount of reflux from the second gas separation membrane unit 12 to the first gas separation membrane unit 11 (S4) was 70 Nm ³ /h, and the amount of reflux from the third gas separation membrane unit 13 to the first gas separation membrane unit 11 ( S5) was 2 Nm ³ /h.
(3) Reoperation When the feed air was supplied to the supply gas line 6 at a supply flow rate of 94 Nm ³ /h, the methane concentration in the impermeable gas of the second gas separation membrane unit 12 recovered to 97.4%.

[Comparative Example 2]
(1) and (3) were carried out in the same manner as in Example 3. The first gas separation membrane unit 11, the second gas separation membrane unit 12, and the third gas separation membrane unit 13 were removed from the gas separation membrane system and individually regenerated. The supply temperature, supply pressure, and supply flow rate of the regeneration gas (compressed air) to each gas separation membrane unit were the same as in the example. The heat amount of the electric heater required for regeneration of the first gas separation membrane unit 11 is 73 kW, the heat amount of the electric heater required for regeneration of the second gas separation membrane unit 12 is 58 kW, and the heat amount required for regeneration of the third gas separation membrane unit 13 is 58 kW. The heat quantity of the electric heater was 3 kW, and a total of 134 kW was required.

The conditions and results of Example 3 and Comparative Example 2 are summarized in Tables 5 and 6 below.

[Example 4]
(1) Gas Separation The procedure was carried out in the same manner as in Example 3, except that the system shown in FIG. 7 was used.
(2) Regeneration The introduction amount of air was set so that the supply flow rate to the second gas separation membrane unit 12 was the same as in the third embodiment. The amount returned from the second gas separation membrane unit 12 to the first gas separation membrane unit 11 (S4) was 0 Nm ³ /h, and the amount returned from the third gas separation membrane unit 13 to the first gas separation membrane unit 11 (S5). was 0 Nm ³ /h. The regeneration treatment was carried out for 3 hours. The required heat quantity of the electric heater required to obtain the same regeneration effect as in FIG. 1 was 71 kW.
(3) Reoperation When the feed air was supplied to the supply gas line 6 at a supply flow rate of 94 Nm ³ /h, the methane concentration in the impermeable gas of the second gas separation membrane unit 12 recovered to 97.4%.

The operating conditions and regeneration conditions of Example 4 are summarized in Tables 7 and 8. In Example 4 using the system of FIG. 7, since there is no recycled gas during regeneration, the oxygen concentration of the air supplied to the first gas separation membrane unit 11 does not increase, and Example 3 using the system of FIG. Compared to , the ratio of the permeating gas in the first gas separation membrane unit 11 can be suppressed. As a result, the amount of air supplied to the first gas separation membrane unit 11 can be reduced by 2% compared to the configuration of FIG. did it.

Claims

A gas separation membrane system comprising at least a first gas separation membrane unit and a second gas separation membrane unit having gas separation performance,
each gas separation membrane unit comprises at least a gas inlet, a permeable gas outlet and an impermeable gas outlet;
A supply gas line is connected to the gas inlet of the first gas separation membrane unit, and compression means and heating means are interposed in the middle of the supply gas line,
connecting the impermeable gas outlet of the first gas separation membrane unit and the gas inlet of the second gas separation membrane unit by a first impermeable gas outlet line;
connecting the permeated gas outlet of the second gas separation membrane unit and a position on the suction side of the compression means in the supply gas line by a second permeated gas return line;
connecting a second impermeable gas discharge line to the impermeable gas discharge port of the second gas separation membrane unit;
connecting the first permeated gas discharge line to the permeated gas discharge port of the first gas separation membrane unit;
After heating the gas for regeneration of the gas separation membrane introduced into the supply gas line to a temperature higher by 10° C. or more and 80° C. or less than during operation for gas separation using the heating means, the first gas separation membrane unit and a gas separation membrane system in communication with the second gas separation membrane unit.
A second permeated gas discharge line branched from the second permeated gas return line is provided, and when the regeneration gas is introduced into the second gas separation membrane unit, the permeated gas of the second gas separation membrane unit is supplied to the supply gas line. 2. The gas separation membrane system of claim 1, adapted to be discharged through said second permeate gas discharge line without returning to.
A first bypass line that connects the position of the heating means in the supply gas line on the first gas separation membrane unit side and the second impermeable gas discharge line, and the position of the heating means in the supply gas line on the first gas separation membrane unit side. a first inlet gas discharge line branching from the supply gas line at a position;
The regeneration gas heated by the heating means is introduced into the second gas separation membrane unit from the impermeable gas outlet through the first bypass line, and the regeneration exhausted from the gas inlet of the first gas separation membrane unit. 3. The gas separation membrane system according to claim 1 or 2, wherein the gas is discharged out of the system through the first inlet gas discharge line.
a second bypass line connecting the first bypass line and the first impermeable gas discharge line; and
comprising a second inlet gas discharge line branching from the first impermeable gas discharge line;
The regeneration gas heated by the heating means is introduced into the first gas separation membrane unit through the non-permeable gas outlet through the second bypass line, and the regeneration gas discharged from the gas inlet of the second gas separation membrane unit. of gas is discharged out of the system through the second inlet gas discharge line.
Further comprising a third gas separation membrane unit having gas separation performance,
the third gas separation membrane unit comprises at least a gas inlet, a permeable gas outlet and an impermeable gas outlet;
connecting the impermeable gas outlet of the third gas separation membrane unit and a position on the suction side of the compression means in the supply gas line by a third impermeable gas return line;
connecting the permeated gas discharge port of the first gas separation membrane unit and the gas inlet of the third gas separation membrane unit by the first permeated gas discharge line;
2. The gas separation membrane system of claim 1, wherein a third permeate gas outlet line is connected to the permeate gas outlet of the third gas separation membrane unit.
A second permeated gas discharge line branched from the second permeated gas return line is provided, and when the regeneration gas is introduced into the second gas separation membrane unit, the permeated gas of the second gas separation membrane unit is returned to the supply gas line. is discharged through the second permeated gas discharge line without
and providing a third impermeable gas discharge line branched from the third impermeable gas return line,
The regeneration gas is also introduced into the third gas separation membrane unit, and the impermeable gas of the third gas separation membrane unit into which the regeneration gas is introduced does not return to the supply gas line. 6. The gas separation membrane system of claim 5, adapted to be discharged through said third non-permeable gas discharge line.
A first bypass line that connects the position of the heating means in the supply gas line on the first gas separation membrane unit side and the second impermeable gas discharge line, and the position of the heating means in the supply gas line on the first gas separation membrane unit side. a first inlet gas discharge line branched from the supply gas line at a position, and the regeneration gas heated by the heating means is passed through the first bypass line to the second gas separation membrane unit through the impermeable gas discharge port. and the regeneration gas discharged from the gas inlet of the first gas separation membrane unit is discharged out of the system through the first inlet gas discharge line. The gas separation membrane system according to .
A second bypass line connecting the first bypass line and the first impermeable gas discharge line, and a second inlet gas discharge line branching from the first impermeable gas discharge line are provided, respectively, and are heated by the heating means for regeneration. The gas is introduced into the first gas separation membrane unit through the second bypass line through the impermeable gas outlet thereof, and the regeneration gas discharged from the gas inlet of the second gas separation membrane unit is the second inlet gas. 8. The gas separation membrane system according to claim 7, which is adapted to be discharged outside the system through a discharge line.
A third unit avoidance line branched from the first permeated gas discharge line is provided, and the permeated gas discharged from the first gas separation membrane unit during regeneration is discharged outside the system without passing through the third gas separation membrane unit. The gas separation membrane system according to any one of claims 5 to 8, enabled.
A third bypass line connecting the first bypass line and the third impermeable gas return line and a third inlet gas discharge line branching from the first permeated gas discharge line are provided, respectively, and the regeneration gas heated by the heating means is The regeneration gas discharged from the gas inlet of the third gas separation membrane unit is introduced through the third bypass line into the third gas separation membrane unit from its impermeable gas discharge port, and the regeneration gas discharged from the gas inlet of the third gas separation membrane unit passes through the third inlet gas discharge line. 10. The gas separation membrane system of claim 9, adapted to be vented to the outside.
The gas separation membrane system according to any one of claims 1 to 10, wherein the regeneration gas is nitrogen, air, or a raw material mixed gas during normal operation.
The gas separation membrane system according to claim 11, wherein the raw material mixed gas during normal operation is biogas or landfill gas.
A method for regenerating a gas separation membrane in a gas separation membrane system comprising at least a first gas separation membrane unit and a second gas separation membrane unit having gas separation performance, comprising:
each gas separation membrane unit comprises at least a gas inlet, a permeable gas outlet and an impermeable gas outlet;
A supply gas line is connected to the gas inlet of the first gas separation membrane unit, and compression means and heating means are interposed in the middle of the supply gas line,
connecting the impermeable gas outlet of the first gas separation membrane unit and the gas inlet of the second gas separation membrane unit by a first impermeable gas outlet line;
connecting the permeated gas outlet of the second gas separation membrane unit and a position on the suction side of the compression means in the supply gas line by a second permeated gas return line;
connecting a second impermeable gas discharge line to the impermeable gas discharge port of the second gas separation membrane unit;
connecting the first permeated gas discharge line to the permeated gas discharge port of the first gas separation membrane unit;
After heating the gas for regeneration of the gas separation membrane introduced into the supply gas line to a temperature higher by 10° C. or more and 80° C. or less than during operation for gas separation using the heating means, the first gas separation membrane unit and a method for regenerating a gas separation membrane, which circulates through the second gas separation membrane unit.
The gas separation membrane system further comprises a third gas separation membrane unit having gas separation performance,
the third gas separation membrane unit comprises at least a gas inlet, a permeable gas outlet and an impermeable gas outlet;
connecting the impermeable gas outlet of the third gas separation membrane unit and a position on the suction side of the compression means in the supply gas line by a third impermeable gas return line;
connecting the permeated gas discharge port of the first gas separation membrane unit and the gas inlet of the third gas separation membrane unit by the first permeated gas discharge line;
14. The regeneration method according to claim 13, wherein a third permeate gas discharge line is connected to the permeate gas discharge port of the third gas separation membrane unit.