Membrane separation system and method for operating membrane separation system

Abstract

Provided is a membrane separation system suitable for efficient recovery of organic compounds. A membrane separation system (100) is provided with: a degassing unit (20) for degassing a fermentation broth (S0) containing a volatile organic compound (C); and a membrane separation unit (10) having a pervaporation membrane (11) for separating the degassed fermentation broth (S) into a permeated fluid (S1) and a non-permeated fluid (S2). The membrane separation unit (10) has a supply space and a permeation space separated by a pervaporation membrane (11). During operation, the pressure in the permeation space of the membrane separation unit (10) is reduced so as to become lower than the pressure in the degassing unit (20).

Description

Technical Field

[0001] The invention relates to a membrane separation system and an operation method of the membrane separation system. Background Art

[0002] Methods for obtaining non-petroleum-derived valuable substances by fermentation based on microorganisms have been proposed. Among them, in recent years, methods for producing volatile organic compounds (fermented products) such as alcohols by fermenting carbon sources such as glucose using microorganisms have been developed. The fermentation of the carbon source is carried out, for example, in an aqueous solution. In this method, if the content of the fermented product in the aqueous solution increases, the fermentation based on the microorganism sometimes stops. In this case, in order to continuously produce the fermented product based on the microorganism, it is necessary to separate the fermented product from the aqueous solution while fermenting.

[0003] As an example of a method for separating volatile organic compounds from an aqueous solution containing the organic compounds, a pervaporation method (pervaporation method) using a pervaporation membrane can be cited. The pervaporation method is suitable for separating volatile organic compounds from aqueous solutions containing various substances. Compared with the distillation method, the pervaporation method also tends to suppress energy consumption and the emission of gases such as carbon dioxide. By combining a membrane separation device for performing the pervaporation method with a fermentation tank for producing fermented products, fermented products can be continuously produced. For example, Patent Document 1 discloses a membrane separation system that combines a membrane separation device and a fermentation tank.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent No. 4048279 Summary of the invention

[0007] Problems to be solved by the invention

[0008] When a feed liquid is separated into a permeated fluid and a non-permeated fluid using a pervaporation membrane, the permeated fluid is usually obtained in a gaseous state. That is, in the pervaporation method, a gaseous permeated fluid is obtained by vaporizing the feed liquid that permeates the pervaporation membrane. The obtained gaseous permeated fluid is liquefied by, for example, cooling in a condensation section provided at the rear stage of the pervaporation membrane to obtain a liquid permeated fluid.

[0009] The inventors of the present application have focused on the close relationship between the fermentation of microorganisms and gases such as carbon dioxide. For example, in the gas fermentation culture method, in order to make the microorganisms ferment, it is necessary to supply gases such as carbon dioxide, oxygen, and hydrogen to the liquid culture medium containing the microorganisms. In addition, during the fermentation process of the carbon source in the aqueous solution, gases such as carbon dioxide are produced as by-products. Therefore, gases are dissolved in the aqueous solution containing volatile organic compounds obtained by fermentation. The inventors of the present application have obtained the following insights, that is, since the permeation vaporization membrane also permeates the gas contained in the supply liquid, gases such as carbon dioxide remain in the permeation fluid of the gas separated by the permeation vaporization membrane. Based on this insight, the inventors of the present application have discovered the problem that gases such as carbon dioxide contained in the permeation fluid of the gas reduce the condensation efficiency in the condensation section of the rear section. The reduction in condensation efficiency will reduce the recovery efficiency of organic compounds.

[0010] Therefore, an object of the present invention is to provide a membrane separation system suitable for efficiently recovering organic compounds.

[0011] Means for solving problems

[0012] The present invention provides a membrane separation system, which comprises:

[0013] a degassing section that degases the fermentation broth containing volatile organic compounds; and

[0014] The membrane separation unit has a pervaporation membrane for separating the degassed fermentation liquid into a permeated fluid and a non-permeated fluid.

[0015] In another aspect, the present invention provides an operating method of a membrane separation system, wherein the membrane separation system comprises a degassing section and a membrane separation section having a pervaporation membrane, the operating method comprising:

[0016] degassing the fermentation broth containing volatile organic compounds by the degassing section; and

[0017] The degassed fermentation liquid is separated into a permeated fluid and a non-permeated fluid by the pervaporation membrane of the membrane separation section.

[0018] Effects of the Invention

[0019] According to the present invention, a membrane separation system suitable for efficiently recovering organic compounds can be provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] [ Figure 1 ] is a schematic configuration diagram showing an example of a membrane separation system according to the present embodiment.

[0021] [ Figure 2 ] is a schematic cross-sectional view showing an example of a membrane separation section included in a membrane separation system.

[0022] [ Figure 3 ] is a schematic cross-sectional view of the pervaporation membrane provided in the membrane separation section.

[0023] [ Figure 4 ] is a schematic cross-sectional view showing an example of a degassing section provided in a membrane separation system.

[0024] [ Figure 5 ] is a schematic cross-sectional view showing an example of a degassing membrane provided in a degassing section.

[0025] [ Figure 6 ] is an expanded stereoscopic view schematically showing another example of a membrane separation section.

[0026] [ Figure 7 ] is an expanded stereoscopic view schematically showing another example of a degassing section.

[0027] [ Figure 8 ] is a schematic diagram showing a modified example 1 of the membrane separation system.

[0028] [ Fig. 9 ] is a schematic diagram showing a modified example 2 of the membrane separation system.

[0029] [ Fig.10 ] is a schematic diagram showing a modified example 3 of the membrane separation system.

[0030] [ Fig.11 ] is a schematic diagram showing a modified example 4 of the membrane separation system.

[0031] [ Fig.12 ] is a schematic diagram showing a modified example 5 of the membrane separation system.

[0032] [ Fig.13 ] is a schematic cross-sectional view showing an example of a membrane separation device provided in the membrane separation system of variant example 5.

[0033] [ Fig.14 ] is a schematic diagram showing a modification example 6 of the membrane separation system. DETAILED DESCRIPTION

[0034] A membrane separation system according to a first aspect of the present invention comprises:

[0035] a degassing section that degases the fermentation broth containing volatile organic compounds; and

[0036] The membrane separation unit has a pervaporation membrane for separating the degassed fermentation liquid into a permeated fluid and a non-permeated fluid.

[0037] In a second aspect of the present invention, for example, in the membrane separation system of the first aspect, the membrane separation section further includes a supply space and a permeation space separated by the pervaporation membrane.

[0038] The membrane separation system further includes a first decompression section that decompresses the permeation space of the membrane separation section, and a second decompression section that decompresses the degassing section.

[0039] In a third aspect of the present invention, for example, in the membrane separation system of the second aspect, during operation, the pressure in the permeation space of the membrane separation section is reduced to a value lower than the pressure in the degassing section.

[0040] In a fourth aspect of the present invention, for example, the membrane separation system according to any one of the first to third aspects further includes a tank for storing the fermentation liquid to be supplied to the degassing section.

[0041] In a fifth aspect of the present invention, for example, the membrane separation system according to any one of the first to fourth aspects further includes a discharge path for discharging the gas separated by the degassing section to the outside of the degassing section.

[0042] In a sixth aspect of the present invention, for example, in the membrane separation system according to any one of the first to fifth aspects, the degassing section includes a degassing membrane that separates gas from the fermentation liquid.

[0043] In a seventh aspect of the present invention, for example, in the membrane separation system of any one of the first to sixth aspects, the membrane separation section is a spiral membrane element.

[0044] The membrane element includes a central tube having a through hole, and a membrane leaf having the pervaporation membrane and wound around the central tube.

[0045] In an eighth aspect of the present invention, for example, in the membrane separation system of the sixth aspect, the degassing section is a spiral membrane element.

[0046] The membrane element includes a central tube having a through hole, and a membrane leaf having the degassing membrane and wound around the central tube.

[0047] In a ninth aspect of the present invention, for example, in the membrane separation system of the sixth or eighth aspect, the material constituting the degassing membrane is the same as the material constituting the pervaporation membrane.

[0048] In a tenth aspect of the present invention, for example, the membrane separation system according to any one of the first to ninth aspects further includes a housing that accommodates the degassing section and the membrane separation section.

[0049] In the 11th aspect of the present invention, for example, in the membrane separation system of the 10th aspect, the membrane separation section also has a supply space and a permeation space separated by the permeation vaporization membrane, and the membrane separation system also has a first decompression section for decompressing the permeation space of the membrane separation section, and a second decompression section for decompressing the degassing section.

[0050] In the twelfth aspect of the present invention, for example, in the membrane separation system of the eleventh aspect, during operation, the pressure in the permeation space of the membrane separation section is reduced to a value lower than the pressure in the degassing section.

[0051] In a 13th aspect of the present invention, for example, in the membrane separation system of any one of the 1st to 12th aspects, the fermentation liquid further contains a microorganism that produces the organic compound,

[0052] An additional separation section for separating the microorganisms from the fermentation liquid is further provided at the upstream stage of the degassing section.

[0053] A membrane separation system operation method according to a fourteenth aspect of the present invention is a membrane separation system operation method including a degassing section and a membrane separation section having a pervaporation membrane, the operation method comprising:

[0054] degassing the fermentation broth containing volatile organic compounds by the degassing section; and

[0055] The degassed fermentation liquid is separated into a permeated fluid and a non-permeated fluid by the pervaporation membrane of the membrane separation section.

[0056] Hereinafter, the present invention will be described in detail, but the following description is not intended to limit the present invention to specific embodiments.

[0057] <Embodiment of membrane separation system>

[0058] like Figure 1 As shown, the membrane separation system 100 of the present embodiment includes a degassing section 20 and a membrane separation section 10 having a permeation membrane. The degassing section 20 is provided at the front section of the membrane separation section 10. The degassing section 20 degasses the fermentation liquid S0 containing the volatile organic compound C. The permeation membrane of the membrane separation section 10 separates the degassed fermentation liquid S into a permeated fluid S1 and a non-permeated fluid S2. It should be noted that, in the present embodiment, "degassing" means removing at least a part or all of the gas contained in the liquid.

[0059] The fermentation liquid S0 is obtained by fermenting a carbon source such as glucose or synthesis gas in an aqueous solution using a microorganism. Therefore, the fermentation liquid S0 contains a volatile organic compound C and a microorganism that generates the organic compound C. The microorganism that generates the organic compound C is typically a bacterium. Usually, during the fermentation of the carbon source in the aqueous solution, gases such as carbon dioxide are produced as byproducts. Therefore, in the fermentation liquid S0 obtained by fermentation, the gas exists as a dissolved gas G. The gas G contains carbon dioxide. The fermentation liquid S0, for example, contains water in addition to the organic compound C, the microorganism and the gas G. The fermentation liquid S0 is typically an aqueous solution containing an organic compound C, a microorganism and the gas G.

[0060] The degassing section 20 separates the gas G dissolved in the fermentation liquid S0 from the fermentation liquid S0. According to the degassing section 20, the fermentation liquid S in which the content of the dissolved gas G is reduced can be produced, so the reduction of the condensation efficiency in the condensation section 40 of the later stage can be suppressed. As a result, the recovery efficiency of the organic compound C is improved. It is believed that this is based on the following reasons. The permeation vaporization membrane of the membrane separation section 10 also permeates the gas contained in the supply liquid. Therefore, if the fermentation liquid S0 containing the gas G is directly supplied to the membrane separation section 10, the gas G remains in the permeated fluid S1 separated by the permeation vaporization membrane. That is, the permeated fluid S1 supplied to the condensation section 40 will contain the gas G. The condensation efficiency in the condensation section 40 depends on the partial pressure of the condensation object gas. For example, in order to condense a mixed gas of ethanol and carbon dioxide, it is necessary to set the cooling temperature of the condensation section 40 lower than the case of condensing a gas with an ethanol concentration of 100%, and more energy is required. In addition, for example, in a mixed gas of ethanol and carbon dioxide, ethanol has a lower contact frequency with the cooling surface of the condenser 40 than in a gas having an ethanol concentration of 100%. For these reasons, the greater the content of gas G in the permeating fluid S1, the lower the condensation efficiency in the condenser 40.

[0061] The membrane separation unit 10 has a pervaporation membrane and a supply space and a permeation space separated by the pervaporation membrane. The membrane separation system 100 further includes a first decompression unit 15 for decompressing the permeation space of the membrane separation unit 10 and a second decompression unit 25 for decompressing the degassing unit 20 .

[0062] The first decompression section 15 and the second decompression section 25 may also be a vacuum device such as a vacuum pump. The vacuum pump is typically a gas-transfer type vacuum pump, and examples thereof include a reciprocating vacuum pump and a rotary vacuum pump. As the reciprocating vacuum pump, a diaphragm type and a swinging piston type vacuum pump can be cited. As the rotary vacuum pump, a liquid ring pump; an oil rotary pump (rotary pump); a mechanical booster pump; various dry pumps such as a Roots type, a claw type, a screw type, a turbine type, and a scroll type can be cited. The pumps for the first decompression section 15 and the second decompression section 25 may also be provided with a variable speed mechanism for changing the rotational speed and the like. An example of the variable speed mechanism is an inverter for the motor driving the pump. By controlling the rotational speed of the pump using the variable speed mechanism, the pressure in the permeation space of the membrane separation section 10 and the pressure in the degassing section 20 can be appropriately adjusted.

[0063] During operation, the pressure P1 (kPa) in the permeation space of the membrane separation section 10 is decompressed to a value lower than the pressure P2 (kPa) in the degassing section 20. That is, during operation, the pressure in the permeation space of the membrane separation section 10 and the pressure in the degassing section 20 are adjusted so as to satisfy P1 / P2 < 1. The adjustment (decompression) of the pressure can be performed by the first decompression section 15 and the second decompression section 25. During operation, the pressure in the permeation space of the membrane separation section 10 and the pressure in the degassing section 20 may also be adjusted so as to satisfy P1 / P2 < 1, preferably P1 / P2 < 0.5, more preferably P1 / P2 < 0.1, and further preferably P1 / P2 < 0.05. It should be noted that when the degassing section 20 is provided with a degassing membrane 21 described later, the "pressure P2 in the degassing section 20" refers to the pressure in the gas space in the liquid space and the gas space of the degassing section 20 through which the gas G separated from the fermentation broth S0 flows.

[0064] The pressure P1 preferably satisfies 0 kPa < P1 ≤ 20 kPa, and more preferably satisfies 0 kPa < P1 ≤ 5 kPa. The pressure P2 preferably satisfies 2 kPa ≤ P2 ≤ 90 kPa, and more preferably satisfies 10 kPa ≤ P2 ≤ 90 kPa.

[0065] The membrane separation system 100 further includes a tank 30 while including the degassing section 20 and the membrane separation section 10. The tank 30 stores the fermentation broth S0 to be supplied to the degassing section 20. The tank 30 may be a fermentation tank for generating an organic compound C based on the carbon source fermentation of microorganisms.

[0066] The membrane separation system 100 further includes a condensation section 40. The condensation section 40 cools and condenses the permeation fluid S1 of the gas transported from the membrane separation section 10. According to the condensation section 40, the permeation fluid S1 of the gas is liquefied to obtain a liquid permeation fluid S1. The condensation section 40 is, for example, a gas-liquid heat exchanger that generates heat exchange between a cooling medium such as antifreeze and the permeation fluid S1 of the gas.

[0067] The membrane separation system 100 further includes a first fermentation liquid supply path 91 , a second fermentation liquid supply path 92 , a non-permeated fluid discharge path 93 , a first permeated fluid discharge path 94 , and a second permeated fluid discharge path 95 as fluid paths.

[0068] The first fermentation liquid supply path 91 is a path for supplying the fermentation liquid S0 from the tank 30 to the degassing section 20 during operation, and is connected to the outlet 30b of the tank 30 and the fermentation liquid inlet 23a of the degassing section 20. The second fermentation liquid supply path 92 is a path for supplying the fermentation liquid S from which the gas G is separated from the degassing section 20 to the membrane separation section 10 during operation, and is connected to the fermentation liquid outlet 23b of the degassing section 20 and the supply space inlet 13a of the membrane separation section 10.

[0069] The non-permeated fluid discharge path 93 is a path for discharging the non-permeated fluid S2 from the membrane separation section 10 during operation, and is connected to the supply space outlet 13b of the membrane separation section 10. For example, a pump for controlling the flow rate of the non-permeated fluid S2 may be arranged in the non-permeated fluid discharge path 93. A pump may not be arranged in the non-permeated fluid discharge path 93.

[0070] The non-permeated fluid discharge path 93 may be configured to be connected to the inlet 30a of the tank 30, and the non-permeated fluid S2 may be delivered to the tank 30 during operation. That is, during operation, the non-permeated fluid S2 may be mixed with the fermentation liquid S0 in the tank 30, and circulated in the first fermentation liquid supply path 91, the second fermentation liquid supply path 92, and the non-permeated fluid discharge path 93. When the non-permeated fluid S2 is delivered to the tank 30, the fermentation liquid S0 and the non-permeated fluid S2 are mixed in the tank 30, and the content of the organic compound C in the fermentation liquid S0 is reduced. When the tank 30 is a fermentation tank, the reduction in the content of the organic compound C in the fermentation liquid S0 can suppress the stop of fermentation by microorganisms, thereby enabling continuous production of fermented products.

[0071] The first permeated fluid discharge path 94 is a path for the permeated fluid S1 for discharging gas from the membrane separation section 10 during operation, and is connected to the permeation space outlet 14b of the membrane separation section 10 and the permeated fluid inlet 40a of the condensation section 40. The second permeated fluid discharge path 95 is a path for the permeated fluid S1 for discharging liquid from the condensation section 40 during operation, and is connected to the permeated fluid outlet 40b of the condensation section 40.

[0072] The membrane separation system 100 may further include a recovery unit 50. The recovery unit 50 recovers the liquid permeated fluid S1 delivered from the condensation unit 40, for example, the liquid permeated fluid S1 can be stored. The recovery unit 50 is, for example, a tank for storing the liquid permeated fluid S1. In this case, the inlet 50a of the recovery unit 50 is connected to the second permeated fluid discharge path 95.

[0073] The membrane separation system 100 further includes a first discharge path 96 and a second discharge path 97 as paths for the fluid.

[0074] The first exhaust path 96 is connected to the exhaust outlet 40c of the condensation section 40. The first decompression section 15 is disposed on the first exhaust path 96. The first decompression section 15 can decompress the inside of the condensation section 40 and the permeation space of the membrane separation section 10. The first decompression section 15 is preferably a vacuum device such as a vacuum pump.

[0075] The second exhaust path 97 is a path for discharging the gas G separated by the degassing section 20 from the degassing section 20 to the outside during operation, and is connected to the exhaust outlet 24b of the degassing section 20. The second exhaust path 97 is provided with a second decompression section 25. The second decompression section 25 can decompress the inside of the degassing section 20. The second decompression section 25 is preferably a vacuum device such as a vacuum pump.

[0076] The membrane separation system 100 may further include a control unit 60 for controlling each component of the membrane separation system 100. The control unit 60 is, for example, a DSP (Digital Signal Processor) including an A / D conversion circuit, an input / output circuit, an operation circuit, a storage device, etc. A program for properly operating the membrane separation system 100 is stored in the control unit 60. For example, the control unit 60 controls the operation of the first decompression unit 15 and the second decompression unit 25, thereby being able to reduce the pressure in the permeation space of the membrane separation unit 10 to a value lower than the pressure in the degassing unit 20.

[0077] Unless otherwise specified, each path of the membrane separation system 100 is constituted by a pipe made of metal or resin, for example.

[0078] The membrane separation system 100 may further include an additional separation section ( Figure 1 (not shown in the figure) According to such a configuration, for example, when the degassing unit 20 includes a degassing membrane 21 described later, clogging of the degassing membrane 21 can be suppressed.

[0079] Next, the membrane separation section 10 and the degassing section 20 included in the membrane separation system 100 of the present embodiment will be described in further detail.

[0080] [Membrane separation section]

[0081] Figure 2 1 is a schematic cross-sectional view showing an example of the membrane separation unit 10. Figure 2As shown, the membrane separation unit 10 includes a pervaporation membrane 11 and a container 12. The container 12 has a first chamber 13 and a second chamber 14. The first chamber 13 functions as a supply space to which the fermentation liquid S is supplied. The second chamber 14 functions as a permeation space to which the permeated fluid S1 is supplied. The permeated fluid S1 is obtained by the fermentation liquid S permeating through the pervaporation membrane 11.

[0082] The pervaporation membrane 11 is disposed inside the container 12. The pervaporation membrane 11 partitions the inside of the container 12 into a first chamber 13 and a second chamber 14. The pervaporation membrane 11 extends from one of a pair of wall surfaces of the container 12 to the other.

[0083] The first chamber 13 has a supply space inlet 13a and a supply space outlet 13b. The second chamber 14 has a permeation space outlet 14b. The supply space inlet 13a is an opening for supplying the fermentation liquid S to the supply space (first chamber 13). The permeation space outlet 14b is an opening for discharging the permeated fluid S1 from the permeation space (second chamber 14). The supply space outlet 13b is an opening for discharging the fermentation liquid S (non-permeated fluid S2) that has not permeated the permeation vaporization membrane 11 from the supply space (first chamber 13). The supply space inlet 13a, the supply space outlet 13b, and the permeation space outlet 14b are each formed, for example, on the wall surface of the container 12.

[0084] The membrane separation section 10 is suitable for a flow-through (continuous) membrane separation method. However, the membrane separation section 10 may also be used for a batch-type membrane separation method.

[0085] (Pervaporation membrane)

[0086] As described above, the pervaporation membrane 11 is typically a membrane (separation membrane) that preferentially permeates the organic compound C contained in the fermentation liquid S. The pervaporation membrane 11 generates a permeated fluid S1 containing the organic compound C as a gas by, for example, the pervaporation method.

[0087] like Figure 3 As shown, the pervaporation membrane 11 includes, for example, a separation functional layer 1 and a porous support 2 supporting the separation functional layer 1. The pervaporation membrane 11 may further include a protective layer (not shown) for protecting the separation functional layer 1. The separation functional layer 1 is, for example, directly in contact with the porous support 2. For example, the main surface 11a of the pervaporation membrane 11 on the separation functional layer side is exposed to the first chamber 13, and the main surface 11b of the porous support side is exposed to the second chamber 14.

[0088] (Separation Functional Layer)

[0089] Typically, the separation functional layer 1 is a layer that allows the organic compound C contained in the fermentation liquid S to preferentially pass through. The separation functional layer 1, for example, includes a hydrophobic material. In this specification, "hydrophobic material" refers to, for example, a material whose static contact angle of water exceeds 90° when a 10 μL drop of water (temperature 25° C.) is dropped on the surface of a test piece composed of the material. It should be noted that the static contact angle of water can be measured using a commercially available contact angle meter.

[0090] As a hydrophobic material, for example, compounds having a siloxane bond (Si-O-Si bond), olefin polymers, oils, fluorine compounds, etc. can be cited. The separation functional layer 1 preferably contains a compound having a siloxane bond as a hydrophobic material. The compound having a siloxane bond is typically an organosilicon polymer. The organosilicon polymer can be solid or liquid at 25°C. As a specific example of an organosilicon polymer, polydimethylsiloxane (PDMS) and the like can be cited. As a specific example of an olefin polymer, polyethylene, polypropylene, etc. can be cited. As an oil, for example, hydrocarbon oils such as liquid paraffin can be cited. As a fluorine compound, polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), etc. can be cited. The hydrophobic material can be used alone or in combination of two or more.

[0091] The separation functional layer 1 may contain a hydrophobic material as a main component, or may be substantially composed of only a hydrophobic material. The "main component" refers to the component that is contained in the largest amount by weight in the separation functional layer 1 .

[0092] The separation function layer 1 may include: a matrix including a hydrophobic material, and fillers dispersed in the matrix. The fillers are embedded in the matrix. In the matrix, all fillers may be separated from each other or partially aggregated.

[0093] The filler includes, for example, inorganic materials such as zeolite, silica, and bentonite. The zeolite contained in the filler is preferably a high-silicon zeolite having a high ratio of silica to alumina. High-silicon zeolite is suitable for separating the fermentation liquid S due to its excellent hydrolysis resistance. As high-silicon zeolite, HSZ (registered trademark) manufactured by Tosoh Corporation, HiSiv (registered trademark) manufactured by United Showa Co., Ltd., USKY manufactured by United Showa Co., Ltd., and Zeoal (registered trademark) manufactured by Nakamura Superhard Co., Ltd. can be used.

[0094] The filler may include a metal-organic framework (MOF). The metal-organic framework is also called a porous coordination polymer (PCP). The metal-organic framework is preferably hydrophobic. The metal-organic framework includes, for example, metal ions and organic ligands. Examples of metal ions include Zn ions. Organic ligands include, for example, aromatic rings. Examples of aromatic rings contained in organic ligands include imidazole rings. Examples of organic ligands include 2-methylimidazole. Specific examples of metal-organic frameworks include ZIF-8.

[0095] The shape of the filler is, for example, particulate. In this specification, "particulate" includes spherical, ellipsoidal, scaly and fibrous. The average particle size of the filler is not particularly limited, for example, it is less than 50 μm, preferably less than 20 μm, and more preferably less than 10 μm. The lower limit of the average particle size of the filler is, for example, 0.01 μm. The average particle size of the filler can be determined, for example, by the following method. First, observe the cross section of the separation functional layer 1 with a transmission electron microscope. In the obtained electron microscope image, the area of ​​a specific filler is calculated by image processing. The diameter of a circle having the same area as the calculated area is regarded as the particle size (diameter of the particle) of the specific filler. The particle sizes of any number (at least 50) of fillers are calculated separately, and the average value of the calculated values ​​is regarded as the average particle size of the filler.

[0096] The content of the filler in the separation functional layer 1 is, for example, 10 wt% or more, preferably 30 wt% or more, and more preferably 40 wt% or more. The upper limit of the content of the filler in the separation functional layer 1 is not particularly limited, and is, for example, 70 wt%. The content of the matrix in the separation functional layer 1 is not particularly limited, and is, for example, 30 wt% to 90 wt%.

[0097] The thickness of the separation functional layer 1 is, for example, 200 μm or less, preferably 100 μm or less, and more preferably 80 μm or less. The thickness of the separation functional layer 1 may be 1.0 μm or more, 10 μm or more, or 30 μm or more.

[0098] The separation functional layer 1 may have a microporous structure with an average pore diameter of less than 0.01 μm, or may be a dense layer with no pores on the surface.

[0099] (Porous Support)

[0100] Examples of the porous support 2 include: nonwoven fabrics; porous polytetrafluoroethylene; aromatic polyamide fibers; porous metals; sintered metals; porous ceramics; porous polyesters; porous nylons; activated carbon fibers; latex; silicone; silicone rubber; a permeable (porous) polymer comprising at least one selected from polyvinyl fluoride, polyvinylidene fluoride, polyurethane, polypropylene, polyethylene, polystyrene, polycarbonate, polysulfone, polyetheretherketone, polyacrylonitrile, polyimide, and polyphenylene ether; a metal foam having open or closed cells; a polymer foam having open or closed cells; silicon dioxide; porous glass; a mesh, and the like. The porous support 2 may be a combination of two or more of these.

[0101] The porous support 2 has an average pore size of, for example, 0.01 to 0.4 μm. The thickness of the porous support 2 is not particularly limited, and is, for example, 10 μm or more, preferably 50 μm or more, and more preferably 100 μm or more. The thickness of the porous support 2 is, for example, 300 μm or less, and preferably 200 μm or less.

[0102] (Protective layer)

[0103] The protective layer, for example, covers the surface of the separation functional layer 1. The material of the protective layer is not particularly limited, and for example, a silicone resin can be cited. The material of the protective layer can also be the same as the material of the matrix of the separation functional layer 1. The thickness of the protective layer is not particularly limited, and for example, it is 0.5 μm or more, preferably 1 μm or more, more preferably 5 μm or more, and further preferably 10 μm or more. The thickness of the protective layer is, for example, 100 μm or less, preferably 50 μm or less, and more preferably 30 μm or less.

[0104] (Method for manufacturing pervaporation membrane)

[0105] The permeation vaporization membrane 11 can be made, for example, by forming a separation functional layer 1 on a porous support 2. In detail, first, a coating liquid containing a material for the separation functional layer 1 is prepared. The coating liquid may contain a filler and a dispersant for dispersing the filler in the coating liquid. In the case where the coating liquid contains a compound having a siloxane bond, the coating liquid may further contain a catalyst for curing the compound. Next, a coating film is obtained by applying the coating liquid on the porous support 2. The separation functional layer 1 is formed by drying the coating film.

[0106] [Degassing section]

[0107] As long as the gas G dissolved in the fermentation liquid S0 can be separated from the fermentation liquid S0, the structure of the degassing section 20 is not particularly limited. The degassing section 20 may be a structure that adopts a decompression method or a structure that adopts a heating method. The degassing section 20 may also be a structure that uses a decompression method and a heating method. As the decompression method, for example, there can be cited a method using a degassing membrane and a method not using a degassing membrane. The method using a degassing membrane is a method of separating dissolved gas in a liquid by gas permeation through a degassing membrane. The method not using a degassing membrane is a method of separating dissolved gas in a liquid by decompressing the space where the liquid exists. The heating method is a method of separating gas by increasing the temperature of the liquid in the degassing tower to reduce the solubility of the dissolved gas in the liquid.

[0108] Figure 4 2 is a schematic cross-sectional view showing an example of the degassing section 20. Figure 4 As shown, the degassing section 20 may include a degassing membrane 21 for separating the gas G from the fermentation liquid S0. That is, the degassing section 20 may be a structure that adopts a decompression method using a degassing membrane.

[0109] Figure 4 The degassing section 20 shown in the figure includes a degassing membrane 21 and a container 22. The container 22 has a first chamber 23 and a second chamber 24. The first chamber 23 is supplied with the fermentation liquid S0, and functions as a liquid space for the fermentation liquid S from which the gas G is separated to flow. The second chamber 24 functions as a gas space for the gas G separated from the fermentation liquid S0 to flow. The fermentation liquid S is obtained by the fermentation liquid S0 passing through the degassing membrane 21.

[0110] The degassing film 21 is disposed inside the container 22. The degassing film 21 partitions the first chamber 23 from the second chamber 24 inside the container 22. The degassing film 21 extends from one of a pair of wall surfaces of the container 22 to the other.

[0111] The first chamber 23 has a liquid space inlet 23a and a liquid space outlet 23b. The second chamber 24 has a gas space outlet 24b. The liquid space inlet 23a is an opening for supplying the fermentation liquid S0 to the liquid space (the first chamber 23). The gas space outlet 24b is an opening for discharging the gas G from the gas space (the second chamber 24). The liquid space outlet 23b is an opening for discharging the fermentation liquid S from which the gas G is separated from the liquid space (the first chamber 23). Each of the liquid space inlet 23a, the liquid space outlet 23b, and the gas space outlet 24b is formed, for example, on the wall surface of the container 22.

[0112] (Degassing membrane)

[0113] As described above, the degassing membrane 21 is typically a membrane (separation membrane) that preferentially permeates the gas G dissolved in the fermentation liquid S0. With respect to the degassing membrane 21, for example, by reducing the pressure in the second chamber 24, only the gas G dissolved in the fermentation liquid S0 supplied to the first chamber 23 is permeated through the second chamber 24. Thus, the fermentation liquid S from which the gas G is separated is obtained.

[0114] like Figure 5 As shown, the degassing membrane 21, for example, includes a separation functional layer 3 and a porous support body 4 supporting the separation functional layer 3. The degassing membrane 21 may also include a protective layer (not shown) for protecting the separation functional layer 3. The separation functional layer 3, for example, is directly in contact with the porous support body 4. The degassing membrane 21, for example, has its main surface 21a on the separation functional layer side exposed to the first chamber 23, and its main surface 21b on the porous support body side exposed to the second chamber 24.

[0115] (Separation Functional Layer)

[0116] Typically, the separation functional layer 3 is a layer that allows the gas G contained in the fermentation liquid S0 to preferentially permeate. The separation functional layer 3 includes, for example, a hydrophobic material. As the hydrophobic material, the hydrophobic material described for the separation functional layer 1 of the pervaporation membrane 11 can be used.

[0117] Similar to the separation functional layer 1 of the pervaporation membrane 11 , the separation functional layer 3 may contain a hydrophobic material as a main component, or may be substantially composed of only a hydrophobic material.

[0118] Separation functional layer 3 may include a matrix containing a hydrophobic material and a filler dispersed in the matrix, similarly to separation functional layer 1 of pervaporation membrane 11. As the filler, the filler described for separation functional layer 1 of pervaporation membrane 11 may be used.

[0119] The thickness of the separation functional layer 3 may be approximately the same as that of the separation functional layer 1 of the pervaporation membrane 11 .

[0120] The separation function layer 3 may have a microporous structure with an average pore diameter of less than 0.01 μm, or may be a dense layer without pores on the surface.

[0121] (Porous Support)

[0122] As the material of porous support 4 , the materials described for porous support 2 of pervaporation membrane 11 can be used.

[0123] (Protective layer)

[0124] The protective layer covers, for example, the surface of separation functional layer 3. As the material of the protective layer, the materials described for the protective layer of the pervaporation membrane 11 can be used.

[0125] The material constituting the degassing membrane 21 may be the same as the material constituting the pervaporation membrane 11. The degassing membrane 21 and the pervaporation membrane 11 may have the same structure as each other except for the membrane area and the thickness of each layer.

[0126] (Method for producing degassing film)

[0127] The degassing membrane 21 can be produced, for example, by forming the separation function layer 3 on the porous support 4. The degassing membrane 21 can be produced by the same method as the method for producing the pervaporation membrane 11 described above.

[0128] <Embodiment of the method for operating the membrane separation system>

[0129] The operation method of the membrane separation system 100 includes degassing a fermentation liquid S0 containing volatile organic compounds C and gas G by the degassing section 20 (step 1), and separating the degassed fermentation liquid S into a permeated fluid S1 and a non-permeated fluid S2 by the permeation vaporization membrane of the membrane separation section 10 (step 2).

[0130] As described above, the fermentation liquid S0 contains the volatile organic compound C and the microorganism that produces the organic compound C. The fermentation liquid S0 contains water in addition to the organic compound C, the microorganism, and the gas G. The fermentation liquid S0 is typically an aqueous solution containing the organic compound C, the microorganism, and the gas G.

[0131] The organic compound C contained in the fermentation liquid S0 is not particularly limited as long as it is volatile. In the present specification, "volatile organic compound" refers to, for example, an organic compound having a boiling point of 20°C to 260°C under atmospheric pressure (101.325 kPa). It should be noted that the organic compound C is a substance that, when the concentration in the aqueous solution is high, produces an aqueous phase containing water as the main component and an organic phase having a higher content of the organic compound C than the aqueous phase.

[0132] The number of carbon atoms in the organic compound C is not particularly limited, and may be, for example, 10 or less, 8 or less, 6 or less, or 4 or less. The lower limit of the number of carbon atoms in the organic compound C may be 1 or 2. The organic compound C may have a functional group containing an oxygen atom, such as a hydroxyl group, a carbonyl group, an ether group, or an ester group. In the organic compound C, the number of functional groups containing an oxygen atom is typically 1.

[0133] As the organic compound C, for example, alcohol, ketone, ester, etc. can be cited, preferably alcohol. In the case where the organic compound C is an alcohol, the organic compound C is easily miscible with water, and the environment in the system is not easy to deviate. The alcohol can be an alkyl alcohol consisting only of an alkyl group and a hydroxyl group, or an aryl alcohol containing an aryl group and a hydroxyl group. The alkyl alcohol can be any of a straight chain, a branched chain, and a cyclic shape. As the alkyl alcohol, for example, methanol, ethanol, n-propanol, isopropanol, n-butanol, 2-butanol, isobutanol, tert-butanol, n-pentanol, etc. can be cited, preferably n-butanol. n-Butanol is a compound that generates two phases (aqueous phase and organic phase) in the aqueous solution when the content rate in the aqueous solution is about 8wt% or more. Therefore, in the case where the organic compound C is n-butanol, for example, by adjusting the content rate of the organic compound C in the permeated fluid S1 to about 8wt% or more, an aqueous phase and an organic phase can be generated in the permeated fluid S1 after liquefaction. In this case, by separating the aqueous phase and the organic phase, the permeated fluid S1 can be easily purified. As the aryl alcohol, for example, phenol can be cited.

[0134] The ketone may be a dialkyl ketone consisting only of an alkyl group and a carbonyl group. Examples of the dialkyl ketone include methyl ethyl ketone (MEK) and acetone.

[0135] The ester may be a fatty acid alkyl ester consisting only of an alkyl group and an ester group. Examples of the fatty acid alkyl ester include ethyl acetate and the like.

[0136] It should be noted that the organic compound C is not limited to the above compounds and may be an aromatic hydrocarbon such as benzene, toluene, or xylene.

[0137] The fermentation liquid S0 may contain one organic compound C, or may contain two or more organic compounds C. The content of the organic compound C in the fermentation liquid S0 may be, for example, 50 wt% or less, 30 wt% or less, 10 wt% or less, 5 wt% or less, 2 wt% or less, or even 1 wt% or less. The lower limit of the content of the organic compound C is not particularly limited, and may be, for example, 0.01 wt%.

[0138] The organic compound C is a fermentation product produced by fermenting a carbon source by a microorganism, and is preferably an alcohol (bioalcohol) produced by the microorganism.

[0139] The fermentation liquid S0 may contain other components such as a carbon source, a nitrogen source, and inorganic ions in addition to water, an organic compound C, microorganisms, and a gas G. Examples of the carbon source include polysaccharides such as starch and monosaccharides such as glucose.

[0140] by Figure 4The specific implementation method of step 1 is described by taking the degassing section 20 as an example. In step 1, first, the fermentation liquid S0 is supplied to the first chamber 23 of the degassing section 20 through the liquid space inlet 23a. Thereby, the fermentation liquid S0 can be brought into contact with one surface (e.g., the main surface 21a) of the degassing membrane 21.

[0141] Next, in a state where the fermentation liquid S0 is in contact with the surface of one side of the degassing membrane 21, the space adjacent to the surface of the other side of the degassing membrane 21 (for example, the main surface 21b) is depressurized. In detail, the second chamber 24 is depressurized through the gas space outlet 24b. The decompression in the second chamber 24 can be performed by the second decompression unit 25. The pressure of the second chamber 24 is, for example, less than 40 kPa, and may also be less than 25 kPa, less than 1 kPa, or less than 6 kPa. It should be noted that in this specification, "pressure" refers to absolute pressure unless otherwise specified.

[0142] By reducing the pressure in the second chamber 24, the gas G separated from the fermentation liquid S0 can be obtained on the other side of the degassing membrane 21. In other words, the gas G is supplied to the second chamber 24. The gas G is discharged to the outside of the degassing section 20 through the gas space outlet 24b. The gas G merges with the exhaust gas of the second decompression section 25 in the second discharge path 97.

[0143] On the other hand, the content of the gas G dissolved in the fermentation liquid S0 gradually decreases from the liquid space inlet 23a toward the liquid space outlet 23b of the first chamber 23. The fermentation liquid S0 (fermentation liquid S) treated by the first chamber 23 is discharged to the outside of the degassing section 20 through the liquid space outlet 23b. The fermentation liquid S passes through the second supply path 92 and from the supply space inlet 13a to be supplied to the membrane separation section 10.

[0144] As described above, in the fermentation liquid S0, a gas such as carbon dioxide exists as a dissolved gas G. In step 1, the gas G dissolved in the fermentation liquid S0 can be separated from the fermentation liquid S0 by the degassing section 20. Therefore, the content of the dissolved gas G in the fermentation liquid S obtained by the operation of the degassing section 20 is lower than that of the fermentation liquid S0 supplied to the degassing section 20. The ratio of the content (wt%) of the gas G in the fermentation liquid S to the content (wt%) of the gas G in the fermentation liquid S0 is not particularly limited.

[0145] According to step 1, since the fermentation liquid S having a reduced content of the dissolved gas G can be produced, it is possible to suppress a decrease in the condensation efficiency of the condensation unit 40 in step 3 described later. As a result, the recovery efficiency of the organic compound C is improved.

[0146] Regarding the specific implementation method of step 2, Figure 2In step 2, first, the fermentation liquid S is supplied to the first chamber 13 of the membrane separation unit 10 through the supply space inlet 13a. Thus, one surface (for example, the main surface 11a) of the pervaporation membrane 11 can be brought into contact with the fermentation liquid S.

[0147] Next, in a state where one surface of the pervaporation membrane 11 contacts the fermentation liquid S, the space adjacent to the other surface of the pervaporation membrane 11 (for example, the main surface 11b) is depressurized. Specifically, the second chamber 14 is depressurized through the permeation space outlet 14b. The depressurization in the second chamber 14 can be performed by the first decompression unit 15. The pressure of the second chamber 14 is, for example, 50 kPa or less, and may be 20 kPa or less, 10 kPa or less, 5 kPa or less, 3 kPa or less, or further may be 2 kPa or less.

[0148] By reducing the pressure in the second chamber 14, a permeate fluid S1 having a high content of organic compound C can be obtained on the other side of the permeation vaporization membrane 11. In other words, the permeate fluid S1 is supplied to the second chamber 14. In the second chamber 14, the permeate fluid S1 is typically a gas. The permeate fluid S1 is discharged to the outside of the membrane separation unit 10 through the permeation space outlet 14b. The permeate fluid S1 passes through the first permeate fluid discharge path 94 and the permeate fluid inlet 40a and is supplied to the condensation unit 40.

[0149] On the other hand, the content of the organic compound C in the fermentation liquid S gradually decreases from the supply space inlet 13a of the first chamber 13 toward the supply space outlet 13b. The fermentation liquid S (non-permeable fluid S2) treated by the first chamber 13 is discharged to the outside of the membrane separation unit 10 through the supply space outlet 13b. The non-permeable fluid S2 is typically a liquid. The non-permeable fluid S2 passes through the non-permeable fluid discharge path 93 and passes through the inlet 30a to be supplied to the tank 30.

[0150] In step 2, the organic compound C contained in the fermentation liquid S can be preferentially permeated through the pervaporation membrane 11 of the membrane separation section 10. Therefore, the permeated fluid S1 obtained by the operation of the membrane separation section 10 has a higher content of the organic compound C than the fermentation liquid S supplied to the membrane separation section 10. The ratio of the content (wt%) of the organic compound C in the permeated fluid S1 to the content (wt%) of the organic compound C in the fermentation liquid S is not particularly limited.

[0151] According to step 2, for example, it is possible to produce the permeated fluid S1 having a high content of the organic compound C. In other words, according to step 2, the organic compound C can be obtained as the permeated fluid S1.

[0152] Steps 1 and 2 also include reducing the pressure in the permeation space of the membrane separation section 10 to a value lower than the pressure in the gas space of the degassing section 20 during operation. For example, by controlling the operation of the first decompression section 15 and the second decompression section 25 using the control section 60, the pressure in the permeation space of the membrane separation section 10 can be reduced to a value lower than the pressure in the gas space of the degassing section 20.

[0153] The operating method of the membrane separation system 100 further includes cooling and condensing the gaseous permeated fluid S1 by the condensation unit 40 (step 3). According to step 3, the gaseous permeated fluid S1 can be liquefied to obtain the liquid permeated fluid S1.

[0154] <Embodiment of the method for producing an organic compound>

[0155] The method for producing an organic compound of the present embodiment includes: degassing a fermentation liquid S0 containing a volatile organic compound C and a gas G; separating the degassed fermentation liquid S into a permeated fluid S1 and a non-permeated fluid S2; and recovering the permeated fluid S1. The method for producing an organic compound of the present embodiment can also be implemented using the above-mentioned membrane separation system 100.

[0156] In the method for producing an organic compound of the present embodiment, the organic compound C may be an alcohol. According to the method for producing an organic compound of the present embodiment, the alcohol can be efficiently separated from the fermentation liquid S0 containing the volatile alcohol.

[0157] [Modification of membrane separation section]

[0158] The membrane separation unit 10 may be a spiral membrane element, a hollow fiber membrane element, a coil-type membrane element in which a plurality of pervaporation membranes are stacked, a plate-and-frame membrane element, or the like. Figure 6 FIG. 1 is a schematic diagram showing an expanded stereogram of a spiral membrane element. The membrane separation unit 10 may also be as follows: Figure 6 The spiral membrane element shown. Figure 6 The membrane separation section 10 (membrane element) includes a central tube 16 and a membrane leaf 17 having a pervaporation membrane 11 and wound around the central tube 16 .

[0159] The center tube 16 has a cylindrical shape. A through hole 16h is formed on the surface of the center tube 16 for allowing the permeable fluid S1 to flow into the interior of the center tube 16. The number of through holes 16h is not particularly limited, and may be one or more than two. Examples of the material of the center tube 16 include resins such as acrylonitrile-butadiene-styrene copolymer resin (ABS resin), polyphenylene ether resin (PPE resin), and polysulfone resin (PSF resin); and metals such as stainless steel and titanium. The inner diameter of the center tube 16 is, for example, in the range of 20 to 100 mm.

[0160] The membrane separation section 10 has a plurality of membrane leaves 17. Each membrane leaf 17 includes a pervaporation membrane 11 and a permeation side flow path material 19. For example, the membrane leaf 17 has two pervaporation membranes 11. The two pervaporation membranes 11 overlap each other and are sealed on three sides in a bag-like structure. The permeation side flow path material 19 is arranged between the two pervaporation membranes 11 so as to be located inside the bag-like structure. The permeation side flow path material 19 ensures a space (permeation space) as a flow path for the permeating fluid S1 between the two pervaporation membranes 11. In this way, the permeation side flow path material 19 is used in combination with the pervaporation membrane 11. The number of membrane leaves 17 is not particularly limited, and is, for example, 2 to 30.

[0161] The membrane separation section 10 further includes a supply side flow path material 18. The supply side flow path material 18 is located outside the bag-like structure and is stacked on the membrane leaves 17. Specifically, a plurality of supply side flow path materials 18 and a plurality of membrane leaves 17 are alternately stacked. The supply side flow path material 18 ensures a space (supply space) as a flow path for the fermentation liquid S between the membrane leaves 17.

[0162] As the supply side flow path material 18 and the permeate side flow path material 19, for example, a net, woven fabric or knitted fabric made of a resin obtained from polyethylene, polypropylene, polyethylene terephthalate (PET), polyphenylene sulfide (PPS) or ethylene-chlorotrifluoroethylene copolymer (ECTFE) can be used.

[0163] The outer circumference of the membrane element is formed by a shell (not shown), which is made of a material that is impermeable to fluid. The shell can be made of FRP (fiber reinforced plastic). The membrane element can be accommodated in a shell (not shown).

[0164] Figure 6 The membrane separation section 10 (membrane element) can be operated, for example, by the following method. First, the fermentation liquid S is supplied to one end of the wound membrane leaf 17. The internal space of the central tube 16 is depressurized. The decompression can be performed by the first decompression section 15. As a result, the permeated fluid S1 of the permeation vaporization membrane 11 that has permeated the membrane leaf 17 moves to the inside of the central tube 16. The permeated fluid S1 is discharged to the outside through the central tube 16. The fermentation liquid S (non-permeated fluid S2) treated by the membrane separation section 10 is discharged to the outside from the other end of the wound membrane leaf 17.

[0165] [Modification of the degassing section]

[0166] The degassing section 20 may also be a spiral membrane element, a hollow fiber membrane element, a coil-type membrane element having a plurality of pervaporation membranes stacked thereon, a plate-and-frame membrane element, etc. Figure 7 The spiral membrane element shown. Figure 7The degassing section 20 (membrane element) includes a central tube 26 and a membrane leaf 27 having a degassing membrane 21 and wound around the central tube 26 .

[0167] The central tube 26 has a cylindrical shape. A through hole 26h is formed on the surface of the central tube 26 for allowing the gas G to flow into the central tube 26. The degassing section 20 has a plurality of membrane leaves 27. Each membrane leaf 27 includes a degassing membrane 21 and a permeation side flow path material 29. The degassing section 20 also has a supply side flow path material 28. Figure 7 The structure of the spiral membrane element Figure 6 The structure of the spiral membrane element is the same, so the detailed description is omitted.

[0168] The degassing section 20 and the membrane separation section 10 may be spiral membrane elements having the same structure except for the membrane area and the thickness of each layer.

[0169] Figure 7 The degassing section 20 (membrane element) can be operated, for example, by the following method. First, the fermentation liquid S0 is supplied to one end of the wound membrane leaf 27. The internal space of the central tube 26 is depressurized. The decompression can be performed by the second decompression section 25. As a result, the gas G that has passed through the degassing membrane 21 of the membrane leaf 27 moves to the inside of the central tube 26. The gas G is discharged to the outside through the central tube 26. The fermentation liquid S0 (fermentation liquid S) treated by the degassing section 20 is discharged to the outside from the other end of the wound membrane leaf 27.

[0170] <Modification of membrane separation system>

[0171] The membrane separation system 100 is not limited to the above-mentioned configuration as long as it includes a degassing section 20 for degassing the fermentation liquid S0 containing the volatile organic compound C and the gas G, and a membrane separation section 10 having a permeation membrane 11 for separating the degassed fermentation liquid S into a permeable fluid S1 and a non-permeable fluid S2. Figures 8 to 13 Modifications 1 to 5 of the membrane separation system 100 will be described. Figure 1 The same reference numerals are used for the common elements of the membrane separation system 100, and detailed description thereof is omitted.

[0172] [Variation 1 of membrane separation system]

[0173] Figure 8 1 is a schematic diagram showing a first modification of the membrane separation system 100. Figure 8 In the membrane separation system 101 shown, the degassing section 20 has a degassing membrane 21 for separating the gas G from the fermentation liquid S0.

[0174] In the membrane separation system 101, the second discharge path 97 is configured to be connected to the inlet 30c of the tank 30, and during operation, the gas G separated by the degassing section 20 is sent to the tank 30. That is, the membrane separation system 101 has a configuration in which the gas G is mixed with the fermentation liquid S0 in the tank 30 during operation, and circulates in the first fermentation liquid supply path 91 and the second discharge path 97. By sending the gas G to the tank 30, the fermentation liquid S0 and the gas G are mixed in the tank 30. By supplying the gas G to the aqueous solution containing microorganisms, the fermentation of the microorganisms can be promoted.

[0175] [Variation 2 of membrane separation system]

[0176] Fig. 9 2 is a schematic diagram showing a second modification of the membrane separation system 100. Fig. 9 In the membrane separation system 102 shown, the degassing unit 20 has a degassing tower 201 for separating the gas G dissolved in the fermentation liquid S0 by heating. The degassing tower 201 increases the temperature of the fermentation liquid S0 in the degassing tower 201 to reduce the solubility of the gas G dissolved in the fermentation liquid S0, thereby separating the gas G from the fermentation liquid S0.

[0177] In the membrane separation system 102, the first fermentation liquid supply path 91 is connected to the outlet 30b of the tank 30 and the fermentation liquid inlet 23a of the degassing tower 201. The second fermentation liquid supply path 92 is connected to the fermentation liquid outlet 23b of the degassing tower 201 and the supply space inlet 13a of the membrane separation section 10. The second discharge path 97 is connected to the exhaust outlet 24b of the degassing tower 201. The second discharge path 97 is connected to the exhaust outlet 24b of the degassing tower 201. The second decompression section 25 for decompressing the inside of the degassing tower 201 may also be arranged on the second discharge path 97. That is, the degassing tower 201 may also be a structure using both the decompression method and the heating method.

[0178] The membrane separation system 102 may further include an additional separation unit 70 for separating microorganisms from the fermentation liquid S0 at the front stage of the degassing tower 201. In this case, the separation unit 70 is arranged in the first fermentation liquid supply path 91. According to such a configuration, for example, the fermentation liquid S0 from which the microorganisms are separated in advance by the separation unit 70 can be supplied to the degassing tower 201, so that the death of the microorganisms due to the temperature rise in the degassing tower 201 can be suppressed.

[0179] The membrane separation system 102 may further include a discharge path 98 as a fluid path. The discharge path 98 is a path for supplying the microorganisms separated by the separation section 70 to the tank 30, and connects the microorganism discharge port 70c of the separation section 70 to the inlet 30d of the tank 30. That is, the membrane separation system 102 has a configuration in which the microorganisms are mixed with the fermentation liquid S0 in the tank 30 during operation, and circulate in a part of the first fermentation liquid supply path 91 and the discharge path 98. By sending the microorganisms to the tank 30, the fermentation liquid S0 and the microorganisms are mixed in the tank 30. By further supplying the microorganisms to the aqueous solution containing the microorganisms, the fermentation of the microorganisms can be promoted.

[0180] In the first fermentation liquid supply path 91, a heat exchanger 81 for heating the fermentation liquid S0 after the microorganisms are separated may be further arranged between the separation section 70 and the degassing tower 201. By supplying the fermentation liquid S0 whose temperature is increased by the heat exchanger 81 to the degassing tower 201, the gas G may be separated from the fermentation liquid S0 in the degassing tower 201.

[0181] In the non-permeated fluid discharge path 93, a heat exchanger 82 for cooling the non-permeated fluid S2 may be further arranged between the membrane separation section 10 and the tank 30. The non-permeated fluid S2 whose temperature has risen due to the treatment in the degassing tower 201 can be cooled by the heat exchanger 82. Thus, the reduction of microorganisms in the fermentation liquid S0 in the tank 30 can be suppressed.

[0182] [Variation 3 of membrane separation system]

[0183] Fig.10 1 is a schematic diagram showing a third modification of the membrane separation system 100. Fig.10 In the membrane separation system 103 shown in FIG. 1 , the degassing section 20 has a degassing membrane 21 instead of a degassing tower 201. Fig. 9 The membrane separation system 102 shown has the same configuration.

[0184] The membrane separation system 103 may further include an additional separation section 70 for separating microorganisms from the fermentation liquid S0 in the upstream stage of the degassing section 20. According to such a configuration, for example, clogging of the degassing membrane 21 in the degassing section 20 can be suppressed.

[0185] [Variation 4 of membrane separation system]

[0186] Fig.11 1 is a schematic diagram showing a fourth modification of the membrane separation system 100. Fig.11 In the membrane separation system 104 shown, the degassing section 20 has a degassing membrane 21 for separating the gas G from the fermentation liquid S0.

[0187] The membrane separation system 104 has the same functions as the first pressure reducing unit 15 and the second pressure reducing unit 25 except that the first pressure reducing unit 15 and the second pressure reducing unit 25 are replaced by a common pressure reducing device 35. Figure 1 In other words, in the membrane separation system 104 , the decompression in the permeation space of the membrane separation section 10 and the decompression in the gas space of the degassing section 20 are performed by one common decompression device 35 .

[0188] The decompression device 35 is disposed in the first discharge path 96. The second discharge path 97 merges with the first discharge path 96 at a merging position 99 located between the condensation unit 40 and the decompression device 35.

[0189] In the first exhaust path 96, a first pressure regulating valve 36 may be disposed between the exhaust outlet 40c of the condensing section 40 and the confluence position 99. In the second exhaust path 97, a second pressure regulating valve 37 may be disposed between the gas space outlet 24b of the degassing section 20 and the confluence position 99. The first pressure regulating valve 36 can adjust the degree of decompression in the permeation space of the membrane separation section 10. The second pressure regulating valve 37 can adjust the degree of decompression in the gas space of the degassing section 20.

[0190] [Variation 5 of membrane separation system]

[0191] Fig.12 1 is a schematic diagram showing a fifth modification of the membrane separation system 100. Fig.12 In the membrane separation system 105 shown, the degassing section 20 has a degassing membrane 21 .

[0192] The membrane separation system 105 has a housing 45 for accommodating the degassing section 20 and the membrane separation section 10. Figure 1 In other words, the membrane separation system 105 includes a membrane separation device 200 including a degassing section 20, a membrane separation section 10, and a housing 45 for housing the degassing section 20 and the membrane separation section 10.

[0193] The shape of the housing 45 is not particularly limited as long as the degassing section 20 and the membrane separation section 10 can be provided in series inside the membrane separation device 200. The housing 45 may have a prismatic shape or a cylindrical shape, for example.

[0194] The housing 45 accommodating the degassing section 20 and the membrane separation section 10 may be placed horizontally or vertically. In the case of vertical placement, the membrane separation section 10 may be located above the degassing section 20, and the membrane separation section 10 may be located below the degassing section 20.

[0195] Fig.131 is a schematic cross-sectional view showing an example of a membrane separation device 200 provided in the membrane separation system 105. In the membrane separation device 200, a degassing section 20 and a membrane separation section 10 are provided in series inside a housing 45. Fig.13 In the example shown, the degassing section 20 and the membrane separation section 10 are spiral membrane elements. However, the structures of the degassing section 20 and the membrane separation section 10 are not limited to the spiral type.

[0196] According to the membrane separation system 105, the membrane separation device 200 is formed by accommodating the degassing section 20 and the membrane separation section 10 in a common housing 45. Compared with the case where the degassing section 20 and the membrane separation section 10 are each accommodated in their own housings, the membrane separation device 200 is lightweight and compact. Therefore, the membrane separation system 105 is suitable for a system requiring lightweight and space saving. In addition, the membrane separation device 200 can be replaced in units of each component, so the maintainability is also excellent.

[0197] The housing 45 includes a housing body 46, a first end plate 46a, and a second end plate 46b. The housing body 46 may be cylindrical and made of a material having sufficient pressure resistance. The length direction of the housing body 46 is consistent with the flow direction of the fluid. The first end plate 46a is mounted on the first end 47a of the housing body 46. The first end 47a of the housing body 46 is closed by the first end plate 46a. The second end plate 46b is mounted on the second end 47b of the housing body 46. The second end 47b of the housing body 46 is closed by the second end plate 46b.

[0198] The housing 45 has a port 48a and a port 48b. The port 48a and the port 48b are ports for connecting the inside and the outside of the housing 45, respectively. The port 48a is provided on the first end plate 46a. The port 48b is provided on the second end plate 46b. The port 48a is a port for guiding the gas G separated in the degassing section 20. The port 48b is a port for guiding the permeated fluid S1 separated by the membrane separation section 10.

[0199] The shell 45 also has a port 49a and a port 49b. The port 49a and the port 49b are ports for connecting the inside and the outside of the shell 45, respectively. The port 49a is provided at the first end 47a of the shell body 46. The port 49b is provided at the second end 47b of the shell body 46. The port 48a is a port for introducing the fermentation liquid S0 into the degassing section 20. The port 48b is a port for guiding the non-permeable fluid S2 separated by the membrane separation section 10. It should be noted that the port 49a may also be provided at the side of the first end 47a side of the shell body 46. The port 49b may also be provided at the side of the second end 47b side of the shell body 46.

[0200] Each of the ports 48a, 48b, 49a and 49b may be a simple opening or may be a Fig.13 The nozzle-shaped opening shown.

[0201] A first tube 55a, a second tube 55b, and a third tube 55c extending in the longitudinal direction are provided inside the housing 45. One end of the first tube 55a is communicated with the central tube 26 of the degassing section 20. The other end of the first tube 55a is communicated with the port 48a. One end of the second tube 55b is communicated with the central tube 26 of the degassing section 20. The other end of the second tube 55b is communicated with the central tube 16 of the membrane separation section 10. One end of the third tube 55c is communicated with the central tube 16 of the membrane separation section 10. The other end of the third tube 55c is communicated with the port 48b.

[0202] A plug 56 is attached to the second tube 55b. During operation, the second tube 55b is blocked by the plug 56. Thus, the pressure in the gas space of the degassing section 20 and the pressure in the permeation space of the membrane separation section 10 can be adjusted separately. Specifically, by controlling the operation of the first decompression section 15 and the second decompression section 25, the pressure in the permeation space of the membrane separation section 10 can be reduced to a value lower than the pressure in the gas space of the degassing section 20. In addition, during operation, the second tube 55b is blocked by the plug 56, thereby preventing the gas G separated by the degassing section 20 from flowing into the membrane separation section 10.

[0203] The membrane separation device 200 further includes a sealing member 57a disposed in the space between the degassing section 20 and the housing 45, and a sealing member 57b disposed in the space between the membrane separation section 10 and the housing 45. The internal space of the housing 45 is partitioned by the sealing members 57a and 57b. The sealing members 57a and 57b have, for example, an annular shape and surround the degassing section 20 and the membrane separation section 10 in the circumferential direction. The sealing members 57a and 57b are disposed on one end side of the degassing section 20 and one end side of the membrane separation section 10.

[0204] The material of the degassing membrane 21 constituting the degassing section 20 is preferably the same as that of the pervaporation membrane 11 constituting the membrane separation section 10. In this case, the membrane separation device 200 can function as a two-stage membrane separation module by, for example, operating with the plug 56 opened.

[0205] [Variation 6 of membrane separation system]

[0206] Fig.14 1 is a schematic diagram showing a sixth modification of the membrane separation system 100. Fig.14In the membrane separation system 106 shown, the degassing section 20 has a degassing membrane 21. The material constituting the degassing membrane 21 is the same as the material constituting the pervaporation membrane 11. The degassing membrane 21 may have the same structure as the pervaporation membrane 11 except for the membrane area and the thickness of each layer. In the membrane separation system 106, the degassing membrane 21 may function as a pervaporation membrane depending on the carbon dioxide concentration of the fluid.

[0207] The membrane separation system 106 includes a CO2 sensor 65 provided in the first fermentation liquid supply path 91 and / or the second fermentation liquid supply path 92, a valve 75 provided in the second discharge path 97, and a switching flow path 76 connecting the valve 75 and the confluence point 94m of the first permeated fluid discharge path 94. Figure 1 The membrane separation system 100 shown has the same configuration.

[0208] The valve 75 is typically a three-way valve having a first inlet port 75a, a first outlet port 75b, and a second outlet port 75c. The first inlet port 75a is connected to the outlet 24b of the degassing section 20 through a portion of the upstream side of the second discharge path 97. The first outlet port 75b is connected to the second pressure reducing section 25 through a portion of the downstream side of the second discharge path 97. The second outlet port 75c is connected to the confluence point 94m through the switching flow path 76.

[0209] The CO2 sensor 65 includes at least one CO2 sensor selected from the first CO2 sensor 65a provided in the first fermentation liquid supply path 91 and the second CO2 sensor 65b provided in the second fermentation liquid supply path 92. The CO2 sensor 65 may be at least one selected from the first CO2 sensor 65a and the second CO2 sensor 65b. That is, the CO2 sensor 65 may be the first CO2 sensor 65a, the second CO2 sensor 65b, or both the first CO2 sensor 65a and the second CO2 sensor 65b.

[0210] The first CO 2 sensor 65a measures the carbon dioxide concentration of the fluid flowing through the first fermentation liquid supply path 91. The second CO 2 sensor 65b measures the carbon dioxide concentration of the fluid flowing through the second fermentation liquid supply path 92.

[0211] <Operation Method of Membrane Separation System of Modification 6>

[0212] Hereinafter, an example of a method for operating the membrane separation system according to Modification 6 will be described.

[0213] (Degassing mode)

[0214] The membrane separation system 106 can be operated, for example, as follows. When the carbon dioxide concentration of the fluid measured by the CO2 sensor 65 is greater than the first threshold value, the first inlet port 75a and the first outlet port 75b of the valve 75 are opened, the second outlet port 75c is closed, and the second pressure reducing unit 25 is driven by the control unit 60. As a result, the degassing membrane 21 of the degassing unit 20 functions as a degassing membrane (degassing mode).

[0215] In the degassing mode, when the carbon dioxide concentration of the fluid measured by the CO2 sensor 65 is greater than the second threshold value (wherein the first threshold value ≤ the second threshold value), the pressure of the second decompression section 25 can be adjusted to be lower by the control section 60. Thus, the degassing performance of the degassing section 20 can be improved (degassing performance improvement mode).

[0216] In the degassing mode, when the carbon dioxide concentration of the fluid measured by the CO2 sensor 65 is below the second threshold value, the pressure of the second decompression unit 25 can be adjusted to be higher by the control unit 60. As a result, the degassing performance of the degassing unit 20 can be reduced (power consumption reduction mode). According to the power consumption reduction mode, the power consumption of the second decompression unit 25 can be reduced.

[0217] (Pervaporation Mode)

[0218] The membrane separation system 106 can be operated, for example, as follows. When the carbon dioxide concentration of the fluid measured by the CO2 sensor 65 is below the first threshold value, the first inlet port 75a and the second outlet port 75c of the valve 75 are opened by the control unit 60, the first outlet port 75b is closed, and the first decompression unit 15 is used for operation. Thus, the degassing membrane 21 of the degassing unit 20 functions as a pervaporation membrane (pervaporation mode). The permeated fluid of the gas discharged from the outlet 24b of the degassing unit 20 flows into the condensation unit 40 through the switching flow path 76 and is condensed.

[0219] The first threshold value can be appropriately set according to the configuration of the membrane separation system 106. As an example, the first threshold value may be 1500 mg / L or less. The lower limit of the first threshold value is not particularly limited, and may be, for example, 200 mg / L or less, or 100 mg / L or less.

[0220] The second threshold value can be appropriately set based on the first threshold value as long as the first threshold value ≤ the second threshold value is satisfied.

[0221] The descriptions of the above embodiments are mutually applicable as long as they are not technically contradictory. The above embodiments and modifications are mutually applicable as long as they are not technically contradictory. For example, the membrane separation system 103 ( Fig.10 )、The membrane separation system 104 of Modification 4 ( Fig.11) and the membrane separation system 105 of Modification 5 ( Fig.12 ) are combined to form a system. For example, the membrane separation system 106 ( Fig.14 ) of the membrane separation system 101 ( Figure 8 )、The membrane separation system 103 of modification example 3 ( Fig.10 )、The membrane separation system 105 of modification example 5 ( Fig.12 )combination.

[0222] Example

[0223] Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited thereto.

[0224] Preparation of separation membrane

[0225] First, a separation membrane is prepared by the following method. 1.650 kg (solid content concentration 30 wt%) of silicone resin (YSR3022 manufactured by Momentive Performance Materials Japan), 2.805 kg of toluene, 0.495 kg of high silica zeolite (HiSiv3000 manufactured by Showa Corporation), 0.0495 kg of silicone curing catalyst (YC6831 manufactured by Momentive Performance Materials Japan), and 0.0495 kg of acetylacetone as a curing retarder are mixed to prepare a coating liquid. Next, a coating film (thickness 500 μm) is obtained by coating the coating liquid on a porous support body (RS-50 manufactured by Nitto Denko Corporation) having a thickness of 150 μm. The coating film is heated at 90°C for 4 minutes to dry it, thereby preparing a separation functional layer having a thickness of 50 μm. In the separation functional layer, the weight ratio of silicone resin to high silica zeolite is 50:50. Thus, a separation membrane is obtained.

[0226] (Example 1)

[0227] Using the separation membrane produced, Figure 1 In detail, in the membrane separation system 100, the above-mentioned separation membrane is used as the pervaporation membrane 11 provided in the membrane separation section 10. The above-mentioned separation membrane is used as the degassing membrane 21 provided in the degassing section 20. The membrane separation section 10 is as follows. Figure 6 The degassing section 20 is as shown in FIG. Figure 7The spiral membrane element shown. As a model fermentation liquid, a fermentation liquid in which CO2 gas was bubbled at 100 mL / min in a 0.8 wt% butanol aqueous solution at 30°C was used. The circulation flow rates of the first fermentation liquid supply path 91, the second fermentation liquid supply path 92 and the non-permeable fluid discharge path 93 were set to 100 g / min. The pressure in the permeation space of the membrane separation section 10 was reduced to 1.5 kPa by the first pressure reducing section 15. The pressure in the degassing section 20 was reduced to 10 kPa by the second pressure reducing section 25. The condensation temperature in the condensation section 40 was set to -7°C, and the electric heating area was set to 0.049 m 2 .

[0228] (Comparative Example 1)

[0229] The operation was carried out under the same conditions as in Example 1 except that the decompression in the degassing section 20 was not performed. Figure 1 The membrane separation system 100 shown. That is, in Comparative Example 1, degassing by the degassing section 20 was not performed.

[0230] The carbon dioxide concentration (mg / L) of the model fermentation liquid discharged from the degassing section 20 was measured by a CO2 sensor (not shown) provided in the second fermentation liquid supply path 92. The amount of butanol (g / hr) contained in the exhaust gas was measured from the exhaust gas of the first decompression section 15. The amount of butanol (%) contained in the exhaust gas was calculated by measuring the flow rate of the gas discharged from the decompression section 15 and the butanol concentration in the exhaust gas. The carbon dioxide concentration of the model fermentation liquid discharged from the decompression section 20 and the amount of butanol contained in the exhaust gas of the first decompression section 15 of Example 1 and Example 2 are shown in Table 1.

[0231] [Table 1]

[0232]

[0233] As shown in Table 1, compared with Comparative Example 1, the amount of butanol contained in the exhaust gas in Example 1 is low, that is, the loss of butanol is low. It is speculated that this is because in Example 1, by separating CO2 from the model fermentation liquid using the degassing section 20, the carbon dioxide concentration is reduced, thereby suppressing the reduction in the condensation efficiency in the subsequent condensation section 40. Figure 1 The membrane separation system 100 shown can suppress the decrease in condensation efficiency in the subsequent condensation section 40 by reducing the content of the dissolved gas G using the degassing section 20, and as a result, can improve the recovery efficiency of the organic compound C.

[0234] Industrial Applicability

[0235] The membrane separation system of the present embodiment is suitable for efficiently recovering organic compounds.

Claims

1. A membrane separation system comprising: a degassing section that degases the fermentation broth containing volatile organic compounds; and The membrane separation unit has a pervaporation membrane for separating the degassed fermentation liquid into a permeated fluid and a non-permeated fluid.

2. The membrane separation system according to claim 1, wherein: The membrane separation section further comprises a supply space and a permeation space separated by the pervaporation membrane. The membrane separation system further includes a first decompression section that decompresses the permeation space of the membrane separation section, and a second decompression section that decompresses the degassing section.

3. The membrane separation system according to claim 2, wherein: During operation, the pressure in the permeation space of the membrane separation section is reduced so as to be lower than the pressure in the degassing section. 4 . The membrane separation system according to claim 1 , further comprising a tank for storing the fermentation liquid to be supplied to the degassing section. 5 . The membrane separation system according to claim 1 , further comprising a discharge path for discharging the gas separated by the degassing section to the outside of the degassing section.

6. The membrane separation system according to claim 1, wherein: The degassing section includes a degassing membrane for separating gas from the fermentation liquid.

7. The membrane separation system according to claim 1, wherein: The membrane separation part is a spiral membrane element. The membrane element includes a central tube having a through hole, and a membrane leaf having the pervaporation membrane and wound around the central tube.

8. The membrane separation system according to claim 6, wherein: The degassing section is a spiral membrane element. The membrane element includes a central tube having a through hole, and a membrane leaf having the degassing membrane and wound around the central tube.

9. The membrane separation system according to claim 6, wherein: The material constituting the degassing membrane is the same as the material constituting the pervaporation membrane. 10 . The membrane separation system according to claim 1 , further comprising a housing for accommodating the degassing section and the membrane separation section.

11. The membrane separation system according to claim 10, wherein: The membrane separation section further comprises a supply space and a permeation space separated by the pervaporation membrane. The membrane separation system further includes a first decompression section that decompresses the permeation space of the membrane separation section, and a second decompression section that decompresses the degassing section.

12. The membrane separation system according to claim 11, wherein: During operation, the pressure in the permeation space of the membrane separation section is reduced so as to be lower than the pressure in the degassing section.

13. The membrane separation system according to claim 1, wherein: The fermentation broth also contains microorganisms that produce the organic compound. An additional separation section for separating the microorganisms from the fermentation liquid is further provided at the upstream stage of the degassing section.

14. A method for operating a membrane separation system, the membrane separation system comprising a degassing section and a pervaporation membrane, the method comprising: Degassing the fermentation liquid containing volatile organic compounds by the degassing section; and The degassed fermentation liquid is separated into a permeated fluid and a non-permeated fluid by the pervaporation membrane of the membrane separation section.

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