Membrane separator and method for controlling membrane separator

Abstract

This membrane separator comprises a membrane separation part, a flow path switching unit, and a concentration sensor. The membrane separation part uses a separation membrane and separates a fluid to be treated, which has been purified in a distillation column, into a first fluid and a second fluid that are different from each other. The flow path switching unit can selectively switch a flow path for the first fluid separated in the membrane separation part, between a first flow path for supplying the first fluid to a supply destination and a second flow path for returning the first fluid to the distillation column. The concentration sensor detects the concentration of the second fluid in the first fluid separated in the membrane separation part. The flow path switching unit switches the flow path from the first flow path to the second flow path at the time when the concentration detected by the concentration sensor has become a preset reference value or higher.

Description

Membrane Separation Device and Control Method for Membrane Separation Device

[0001] The present disclosure relates to a membrane separation device and a control method for a membrane separation device. The present application claims priority based on Japanese Patent Application No. 2025-066034 filed with the Japan Patent Office on April 14, 2025, the content of which is incorporated herein by reference.

[0002] A membrane separation device is known that can separate a fluid to be treated into a permeate fluid that has permeated through a separation membrane and a non-permeate fluid that does not permeate through the separation membrane using the separation membrane (for example, Patent Document 1).

[0003] Japanese Unexamined Patent Publication No. 2009-263335

[0004] In a membrane separation device such as that described in Patent Document 1 above, if any abnormality occurs in the membrane separation unit, its separation performance deteriorates, which may increase the amount of the non-permeate fluid leaking into the permeate fluid and raise the concentration of the non-permeate fluid. The concentration of the non-permeate fluid in the permeate fluid is required to satisfy a predetermined reference value specified, for example, by the supply destination of the permeate fluid. Therefore, when the concentration exceeds the reference value due to the occurrence of such an abnormality, the operation of the membrane separation device has to be interrupted to stop the supply of the permeate fluid to the supply destination, leading to a reduction in the operation rate of the membrane separation device.

[0005] At least one embodiment of the present disclosure has been made in view of the above circumstances, and an object thereof is to provide a membrane separation device and a control method for a membrane separation device that can suppress a reduction in operation rate while avoiding supplying a permeate fluid having a concentration exceeding a reference value to a supply destination when an abnormality occurs in the membrane separation unit.

[0006] A membrane separation apparatus according to at least one embodiment of the present disclosure, in order to solve the above problems, comprises: a membrane separation unit for separating a fluid to be treated, purified in a distillation column, into a first fluid and a second fluid, which are different from each other, using a separation membrane; a flow path switching unit that can selectively switch between a first flow path for supplying the first fluid to a destination, or a second flow path for returning the first fluid to the distillation column, as the flow path for the first fluid separated in the membrane separation unit; and a concentration sensor for detecting the concentration of the second fluid in the first fluid separated in the membrane separation unit, wherein the flow path switching unit switches the flow path from the first flow path to the second flow path when the concentration detected by the concentration sensor becomes equal to or greater than a preset reference value.

[0007] A control method for a membrane separation apparatus according to at least one embodiment of the present disclosure, in order to solve the above problems, comprises: a membrane separation unit for separating a fluid to be treated, purified in a distillation column, into a first fluid and a second fluid that are different from each other, using a separation membrane; and a flow path switching unit that can selectively switch between a first flow path for supplying the first fluid to a supply destination, or a second flow path for returning the first fluid to the distillation column, as the flow path for the first fluid separated in the membrane separation unit, the control method for a membrane separation apparatus comprising: detecting the concentration of the second fluid in the first fluid separated in the membrane separation unit; and controlling the flow path switching unit to switch the flow path from the first flow path to the second flow path when the concentration becomes equal to or greater than a preset reference value.

[0008] According to at least one embodiment of this disclosure, it is possible to provide a membrane separation apparatus and a control method for the membrane separation apparatus that can suppress a decrease in operating rate while avoiding the supply of permeate fluid having a concentration exceeding a standard value to a destination when an abnormality occurs in the membrane separation section.

[0009] This figure shows the overall configuration of a membrane separation apparatus according to one embodiment. This figure shows the configuration when the flow path switching unit in Figure 1 is controlled to the second switching state. This flowchart shows the control method of the membrane separation apparatus implemented by the control device in Figure 1. This is an example of the configuration of the membrane separation unit in Figure 1, which includes a plurality of membrane separation modules. This is a modified example of Figure 4. This figure schematically shows the connection configuration of the plurality of membrane separation modules in Figure 5. This figure shows the configuration when a membrane separation module that has malfunctioned in Figure 6A is switched with a spare module. This flowchart shows the control method of a membrane separation apparatus according to one embodiment.

[0010] Hereinafter, several embodiments of the present invention will be described with reference to the attached drawings. However, the dimensions, materials, shapes, relative arrangements, etc., of the configurations described or shown in the drawings as embodiments are not intended to limit the scope of the present invention, but are merely illustrative examples.

[0011] Figure 1 shows the overall configuration of a membrane separation apparatus 1 according to one embodiment. The membrane separation apparatus 1 is a device for separating a fluid to be processed Q0 into a first fluid Q1 and a second fluid Q2. The fluid to be processed Q0 handled by the membrane separation apparatus 1 is not limited. In the following embodiment, as an example of the fluid to be processed Q0, a crude ethanol aqueous solution obtained by purifying a fermented ethanol aqueous solution is used as the fluid to be processed Q0, and a case in which it is separated into water as the first fluid Q1 and anhydrous ethanol as the second fluid Q2 will be described.

[0012] The membrane separation apparatus 1 includes a fermentation tank 10 as a configuration for producing a crude ethanol aqueous solution, which is the fluid to be processed Q0. The fermentation tank 10 is configured to produce a fermented ethanol aqueous solution, which is the raw material for the crude ethanol aqueous solution, by fermenting raw materials such as sugar-based, starch-based, or cellulose-based materials. The fermented ethanol aqueous solution is a mixed fluid that contains ethanol and water, as well as a considerable amount of impurities. The impurities contained in the fermented ethanol aqueous solution include, for example, yeast and bacteria, but may also contain other components.

[0013] The fermented ethanol aqueous solution produced in the fermentation tank 10 is supplied to the distillation column 12 via line L1. In the distillation column 12, distillation is performed on the fermented ethanol aqueous solution to remove impurities and to perform rough separation of the components to be separated in the membrane separation unit 22 (ethanol and water). The vapor containing ethanol and water obtained in the distillation column 12 is supplied to the condenser 14 via line L2 from the top of the distillation column 12. In the condenser 14, the vapor from the distillation column 12 is cooled by heat exchange with a heat transfer medium, and a crude ethanol aqueous solution is produced.

[0014] The crude ethanol aqueous solution produced in the condenser 14 is stored in the primary tank 18 via line L3. The crude ethanol aqueous solution stored in the primary tank 18 is further supplied to the secondary tank 20 via line L4. Line L4 is equipped with a pump 17 for sending the crude ethanol aqueous solution flowing through line L4 to the secondary tank 20. Downstream of the pump 17 in line L4, line L5 branches off to return a portion of the crude ethanol aqueous solution supplied by the pump 17 to the distillation column 12. The crude ethanol aqueous solution stored in the secondary tank 20 is supplied to the membrane separation unit 22 as the fluid to be treated Q0 via line L6. In the following description, the crude ethanol aqueous solution supplied to the membrane separation unit 22 will be referred to as the fluid to be treated Q0 as appropriate.

[0015] Furthermore, line L6 is equipped with a pump 19 for sending the fluid to be processed Q0, and a preheater 21 for heating the fluid to be processed Q0 supplied to the membrane separation unit 22.

[0016] The membrane separation unit 22 is a device for separating the fluid to be processed Q0 into a first fluid Q1 and a second fluid Q2 using a separation membrane 24. Of the first fluid Q1 and the second fluid Q2, one is an impermeable fluid that does not permeate the separation membrane 24, and the other is a permeable fluid that permeates the separation membrane 24. In this embodiment, as described above, we will exemplify the case in which the fluid to be processed Q0 is separated by the membrane separation unit 22 into water, which is the first fluid Q1, and anhydrous ethanol, which is the second fluid Q2. In this case, water, which is the first fluid Q1, is a permeable fluid that permeates the separation membrane 24, and anhydrous ethanol, which is the second fluid Q2, is an impermeable fluid that does not permeate the separation membrane 24. Depending on the components contained in the fluid to be processed Q0 and the type of separation membrane 24, the first fluid Q1 may be an impermeable fluid that does not permeate the separation membrane 24, and the second fluid Q2 may be a permeable fluid that permeates the separation membrane 24.

[0017] The membrane separation unit 22 includes at least one membrane separation module 25 for separating the fluid to be processed into a first fluid Q1 and a second fluid Q2 using a separation membrane 24. Figure 1 illustrates the case in which the membrane separation unit 22 comprises a single membrane separation module 25 in order to provide a conceptual overview of the present invention.

[0018] The membrane separation module 25 has a primary channel 28 and a secondary channel 30 separated from each other by a separation membrane 24 within the container 26. The fluid to be processed Q0 is introduced into the primary channel 28 from a primary inlet 32 ​​located upstream of the membrane separation module 25. As the fluid to be processed Q0 (crude ethanol aqueous solution) flows through the primary channel 28, the first fluid Q1 (water) is separated, and the second fluid Q2 (anhydrous ethanol) is discharged as a second fluid Q2 (anhydrous ethanol) from a primary outlet 34 located downstream of the membrane separation module 25 via line L7.

[0019] The second fluid Q2 (anhydrous ethanol) discharged from line L7 is supplied via line L7 to a destination (not shown) for the second fluid Q2. The destination for the second fluid Q2 is, for example, another plant facility that requires the second fluid Q2. When the membrane separation unit 22 is functioning normally, the concentration of the first fluid Q1 in the second fluid Q2 flowing through line L7 is below a predetermined reference value. This reference value is set, for example, based on the requirements of the destination for the second fluid Q2.

[0020] Meanwhile, the first fluid Q1 (water) separated in the membrane separation section 22 is discharged through line L8 from a secondary outlet section 36 provided in the secondary flow path 30. Line L8 branches into line L9 (first flow path) and line L10 (second flow path) from a confluence point 38 provided downstream of it. Line L8 is also equipped with a concentration sensor 27 for detecting the concentration of the second fluid Q2 in the first fluid Q1 flowing through line L8.

[0021] Line L9 is a flow path for supplying the first fluid Q1 separated in the membrane separation unit 22 to the supply destination of the first fluid Q1, and connects the confluence point 38 to the supply destination of the first fluid Q1. The supply destination of the first fluid Q1 may be a drainage system (not shown) or the aforementioned fermentation tank 10. Line L10 is a flow path for returning the first fluid Q1 separated in the membrane separation unit 22 to the distillation column 12, and connects the confluence point 38 to the distillation column 12. The first fluid Q1 returned to the distillation column 12 via line L10, together with the fermentation ethanol aqueous solution supplied via line L1, undergoes distillation treatment again in the distillation column 12.

[0022] Furthermore, the membrane separation device 1 includes a flow path switching unit 40 that can selectively switch between the aforementioned lines L9 or L10 as the flow path for the first fluid Q1 separated in the membrane separation unit 22. The flow path switching unit 40 includes, for example, a first valve V1 provided in line L9 and a second valve V2 provided in line L10. By switching the open / closed states of the first valve V1 and the second valve V2, it is possible to select either line L9 or L10 as the flow path for the first fluid Q1 flowing through line L8.

[0023] Figure 1 shows a flow path in which the first fluid Q1 flowing through line L8 is supplied to the destination via line L9, as line L9 is selected by the flow path switching unit 40. In the following description, the state in which line L9 is selected as the flow path through which the first fluid Q1 separated in the membrane separation unit 22 flows will be referred to as the "first switching state". In the first switching state, as shown in Figure 1, the first valve V1 is in the open state and the second valve V2 is in the closed state. In this case, the first fluid Q1 separated in the membrane separation unit 22 is supplied to the destination via line L9.

[0024] On the other hand, Figure 2 shows a flow path in which the first fluid Q1 flowing through line L8 is returned to the distillation column 12 via line L10, as line L10 is selected by the flow path switching unit 40. In the following description, the state in which line L10 is selected as the flow path through which the first fluid Q1 separated in the membrane separation unit 22 flows will be referred to as the "second switching state". In the second switching state, as shown in Figure 2, the first valve V1 is in the closed state and the second valve V2 is in the open state. In this case, the first fluid Q1 separated in the membrane separation unit 22 is returned to the distillation column 12 via line L10 without being supplied to the destination.

[0025] The membrane separation apparatus 1 includes a control unit 100 for controlling the above configuration. The control unit 100 consists of, for example, a CPU (Central Processing Unit), RAM (Random Access Memory), ROM (Read Only Memory), and a computer-readable storage medium. A series of processes for realizing various functions are stored in the storage medium in the form of a program, for example. The CPU reads this program into the RAM and executes information processing and calculations to realize the various functions. The program may be pre-installed on the ROM or other storage medium, provided in a state where it is stored on a computer-readable storage medium, or distributed via wired or wireless communication. Computer-readable storage media include magnetic disks, magneto-optical disks, CD-ROMs, DVD-ROMs, semiconductor memory, etc.

[0026] The control device 100 includes a concentration detection unit 110 and a flow path control unit 120.

[0027] The concentration detection unit 110 is configured to detect the concentration of the second fluid Q2 in the first fluid Q1 flowing through line L8 based on the detection signal from the concentration sensor 27. The concentration detection unit 110 monitors the concentration by acquiring the detection signal from the concentration sensor 27 at predetermined time intervals (sampling frequency) or continuously.

[0028] The flow path control unit 120 is configured to switch the flow path of the first fluid Q1 separated in the membrane separation unit 22 by controlling the flow path switching unit 40 based on the concentration detected by the concentration detection unit 110. If the concentration detected by the concentration detection unit 110 is less than the reference value, the flow path control unit 120 controls the flow path switching unit 40 to the first switching state. In this case, as shown in Figure 1, the first valve V1 is in the open state and the second valve V2 is in the closed state, so the first fluid Q1 separated in the membrane separation unit 22 is supplied to the supply destination via line L9. At this time, the concentration of the second fluid Q2 in the first fluid Q1 supplied to the supply destination is less than the reference value and satisfies the supply destination's requirements.

[0029] On the other hand, if the concentration detected by the concentration detection unit 110 is equal to or greater than the standard value, the flow path control unit 120 controls the flow path switching unit 40 to the second switching state. In this case, as shown in Figure 2, the first valve V1 is in the closed state and the second valve V2 is in the open state, so the first fluid Q1 separated in the membrane separation unit 22 is returned to the distillation column 12 via the line L10. This prevents the supply of the first fluid Q1 whose concentration does not meet the standard value to the supply destination, and by returning the first fluid Q1 to the distillation column 12, the operation of the membrane separation apparatus 1 can be suitably continued.

[0030] In this embodiment, the operation of the membrane separation device 1 is described as being automatically controlled by the control device 100, but at least a part of the operation of the membrane separation device 1 may be performed manually by an operator.

[0031] Figure 3 is a flowchart showing the control method of the membrane separation apparatus 1 implemented by the control device 100 shown in Figure 1.

[0032] First, in the initial state, the membrane separation device 1 is operated in the normal state (step S10). In the normal state, the flow path switching unit 40 is in the first switching state. In the first switching state, as shown in Figure 1, the first valve V1 is open and the second valve V2 is closed, so the first fluid Q1 separated in the membrane separation unit 22 is supplied to the supply destination via line L9.

[0033] Next, the concentration detection unit 110 detects the concentration of the second fluid Q2 in the first fluid Q1 separated by the membrane separation unit 22 by acquiring the detection signal from the concentration sensor 27 (step S11). The concentration detection in step S11 is performed repeatedly at predetermined time intervals or continuously, thereby monitoring the concentration of the second fluid Q2 in the first fluid Q1.

[0034] Next, the control device 100 determines whether the concentration detected in step S11 is above or below the reference value (step S12). If the concentration is below the reference value (step S12: NO), the control device 100 continues monitoring the concentration by returning the process to step S11. In this case, since the concentration of the second fluid Q2 in the first fluid Q1 meets the reference value, the membrane separation device 1 continues to operate normally, and the first fluid Q1 separated in the membrane separation unit 22 is supplied to the destination via line L9.

[0035] On the other hand, if the concentration is above the standard value (step S12: YES), the flow path control unit 120 controls the flow path switching unit 40 to switch to the second switching state (step S13). In the second switching state, as shown in Figure 2, the first valve V1 is closed and the second valve V2 is open. Therefore, if the concentration of the second fluid Q2 in the first fluid Q1 does not meet the standard value, the supply of the first fluid Q1 to the supply destination is prevented. At this time, the first fluid Q1 is returned to the distillation column 12 via line L10, so that the membrane separation apparatus 1 can continue to operate comfortably while stopping the supply of the first fluid Q1 to the supply destination.

[0036] Figure 4 shows an example of the configuration of the membrane separation unit 22 of Figure 1, which includes multiple membrane separation modules 25. In Figure 4, the membrane separation unit 22 is illustrated as having four membrane separation modules 25a to 25d having equivalent configurations, but the number of membrane separation modules 25 included in the membrane separation unit 22 is not limited. In this case, the line L8 through which the first fluid Q1 separated in the membrane separation unit 22 flows is configured to include lines L8a to L8f.

[0037] The first fluid Q1 separated in each membrane separation module 25 is discharged through a plurality of lines L8a connected to the secondary outlet 36 of each membrane separation module 25. Each of the plurality of lines L8a is provided with shut-off valves V3a to V3d. The first fluid Q1 flowing through the plurality of lines L8a merges with line L8b and is introduced into the condenser 41. The first fluid Q1 condensed in the condenser 41 is stored in the buffer tank 42 via line L8c. A pressure reducing pump 44 is connected to the buffer tank 42 to apply negative pressure. The bottom of the buffer tank 42 stores the condensed liquid phase of the first fluid Q1, and the space above it is filled with the gas phase of the first fluid Q1. The pressure reducing pump 44 applies negative pressure from the gas phase region of the buffer tank 42 across lines L8a, L8b, and L8c.

[0038] The first fluid Q1 stored in the buffer tank 42 is supplied to the booster pump 46 via line L8d from the bottom of the buffer tank 42. The booster pump 46 sends the first fluid Q1 to the confluence point 38 via line L8e. Upstream of the booster pump 46, as described above, negative pressure from the depressurizing pump 44 acts on the flowing first fluid Q1, but downstream of the booster pump 46, the first fluid Q1 is sufficiently pressurized. Therefore, by installing a concentration sensor 27 in line L8f branching from line L8e, the concentration of the first fluid Q1 can be monitored by the concentration sensor 27 with a simple configuration (for example, it is not necessary to add a pump to line L8f to pressurize the first fluid Q1 in order to supply the first fluid Q1 to the concentration sensor 27). The first fluid Q1 that has passed through the concentration sensor 27 is returned to the buffer tank 42.

[0039] In the membrane separation unit 22, which is equipped with multiple membrane separation modules 25, if an abnormality occurs in at least one membrane separation module 25, such as deterioration or rupture of the separation membrane, the concentration detected by the concentration sensor 27 will exceed a standard value, and an abnormality will be detected. When an abnormality is detected, the flow path switching unit 40 can be set to the second switching state as described above, thereby stopping the supply of the first fluid Q1 to the supply destination while continuing to operate the membrane separation device 1.

[0040] FIG. 5 is a modification of FIG. 4. In this modification, the membrane separation device 1 includes a diagnosis unit 50 for diagnosing the location where an abnormality occurs while the operation of the membrane separation device 1 is continued with the flow path switching unit 40 set to the second switching state.

[0041] The diagnosis unit 50 includes a plurality of lines L11a to L11d branched from each of the plurality of lines L8a, a plurality of shutoff valves V4a to V4d respectively provided in the plurality of lines L11a to L11d, and an analyzer 52 to which the plurality of lines L11a to L11d are connected. A part of the first fluid Q1 flowing through each of the plurality of lines L8a can be extracted via the plurality of lines L11a to L11d and supplied to the analyzer 52 when the shutoff valves V4a to V4d provided in the corresponding lines L11a to L11d are in an open state.

[0042] As described above, negative pressure from the decompression pump 44 acts on the plurality of lines L11a to L11d, and the first fluid Q1 flowing through each of the lines L11a to L11d can be suitably supplied to the analyzer 52 by being pressurized by pressurization units 54a to 54d respectively provided in the lines L11a to L11d.

[0043] The diagnosis unit 50 can diagnose which of the plurality of membrane separation modules 25 has an abnormality by detecting a concentration change with the analyzer 52 while operating each of the shutoff valves V4a to V4d according to a predetermined opening / closing pattern. For example, each of the shutoff valves V4a to V4d is sequentially opened one by one (the other three valves are in a closed state at this time), and when the concentration detected by the analyzer 52 is equal to or higher than a reference value, it can be diagnosed that there is an abnormality in the membrane separation module 25 corresponding to the shutoff valve V4a to V4d that has been in the open state.

[0044] Subsequently, another example of the connection configuration of the plurality of membrane separation modules 25 provided in the membrane separation unit 22 will be described. FIG. 6A is a diagram schematically showing the connection configuration of the plurality of membrane separation modules 25 in FIG. 5.

[0045] In this configuration example, the plurality of membrane separation modules 25 are connected in series to each other in the flow direction of the fluid to be treated Q0. The fluid to be treated Q0 can be supplied to the membrane separation module 25a located on the most upstream side via a line L6. Further, the adjacent membrane separation modules 25 are connected to each other via a line L12. Thereby, the second fluid Q2 separated by the upstream membrane separation module 25 is supplied to the downstream membrane separation module 25 via the line L12, so that the first fluid Q1 is further separated from the second fluid Q2. The first fluids Q1 separated by each membrane separation module 25 merge with each other and are discharged from a line L8.

[0046] A valve V5 and a valve V6 are respectively provided at the primary-side inlet portion and the primary-side outlet portion of each membrane separation module 25. Further, each membrane separation module 25 is provided with a bypass line L13 that connects the upstream side of the valve V5 and the downstream side of the valve V6. A valve V7 is provided on the bypass line L13.

[0047] The plurality of membrane separation modules 25 may include at least one spare module. In the configuration example of Fig. 6A, the membrane separation module 25d located on the most downstream side is the spare module, but the position of the spare module is not limited thereto. In a normal state, as shown in Fig. 6A, the valves V5 and V6 corresponding to the spare module 25d are closed, and the valve V7 is opened, so that the spare module 25d is in a dormant state.

[0048] Here, when an abnormality occurs in the hatched membrane separation module 25b in Fig. 6A, as shown in Fig. 6B, by switching the open / closed state of each of the valves V5, V6, and V7, the membrane separation module 25b in which the abnormality has occurred is isolated, and the spare module 25d is activated, whereby the separation performance of the membrane separation unit 22 can be maintained.

[0049] Fig. 7 is a flowchart showing a control method for the membrane separation device 1 according to one embodiment. Among the steps shown in Fig. 7, steps S10 to S13 are the same as those in Fig. 3, and thus the description thereof will be omitted as appropriate unless otherwise specified.

[0050] In step S13, when the concentration detected by the concentration sensor 27 exceeds the reference value, and the switching state of the flow path switching unit 40 becomes the second switching state, the abnormal membrane separation module 25b and the spare module 25d are switched, as described above with reference to Figures 6A and 6B. At this time, the spare module 25d, which was in a dormant state, requires a start-up operation to raise the module temperature to a predetermined value in order to fully exhibit separation performance. Therefore, in this embodiment, when the switching state of the flow path switching unit 40 becomes the second switching state in step S13, the start-up operation of the spare module 25d is started (step S14). Then, when the start-up operation is completed (step S15: YES), the switching between the abnormal membrane separation module 25b and the spare module 25d is performed (step S16). The flow path control unit 120 then returns the membrane separation device 1 to the normal state by changing the switching state of the flow path switching unit 40 to the first switching state (step S17).

[0051] By performing the startup operation of the backup module 25d while the flow path switching unit 40 is in the second switching state, the membrane separation device 1 can be switched between the malfunctioning membrane separation module 25b and the backup module 25d without stopping the membrane separation device 1. As a result, even if a malfunction occurs in the membrane separation module 25b, the operating rate of the membrane separation device 1 will not decrease.

[0052] This disclosure is not limited to the embodiments described above, but also includes modified forms of the embodiments described above, as well as forms that combine these forms as appropriate.

[0053] The contents described in each of the above embodiments can be understood, for example, as follows:

[0054] (1) A membrane separation apparatus according to one embodiment includes: a membrane separation unit for separating a fluid to be treated, purified in a distillation column, into a first fluid and a second fluid, which are different from each other, using a separation membrane; a flow path switching unit that can selectively switch between a first flow path for supplying the first fluid to a destination, or a second flow path for returning the first fluid to the distillation column, as the flow path for the first fluid separated in the membrane separation unit; and a concentration sensor for detecting the concentration of the second fluid in the first fluid separated in the membrane separation unit, wherein the flow path switching unit switches the flow path from the first flow path to the second flow path when the concentration detected by the concentration sensor becomes equal to or greater than a preset reference value.

[0055] According to the embodiment of (1) above, if the concentration of the second fluid in the first fluid separated in the membrane separation unit exceeds a reference value, the first fluid separated in the membrane separation unit is returned to the distillation column via the second flow path. This prevents the first fluid with a concentration above the reference value from being supplied to the recipient, while allowing the operation of the membrane separation apparatus to continue.

[0056] (2) In another embodiment, in the embodiment of (1) above, the flow path switching unit is switched to select the first flow path as the flow path when the concentration detected by the concentration sensor is less than the reference value.

[0057] According to the embodiment of (2) above, if the concentration is below the reference value, the first fluid separated in the membrane separation unit is suitably supplied to the recipient via the first flow path.

[0058] (3) In other embodiments, in the embodiment of (1) or (2) above, the flow path switching unit includes a first valve provided in the first flow path and a second valve provided in the second flow path, and is configured to switch the flow path by opening and closing the first valve and the second valve, respectively.

[0059] According to the embodiment of (3) above, the flow path of the first fluid separated in the membrane separation section can be suitably switched by switching the open and closed states of the first valve and the second valve, which are provided in the first flow path and the second flow path, respectively.

[0060] (4) In other embodiments, in any one embodiment of (1) to (3) above, the device comprises: a condenser for condensing the first fluid; a buffer tank for storing the first fluid condensed in the condenser; a depressurizing pump for applying negative pressure to the membrane separation unit via the condenser and the buffer tank; and a boost pump for pressurizing the first fluid stored in the buffer tank and supplying it to the supply destination, wherein the concentration sensor is provided to detect the concentration of the first fluid pressurized by the boost pump.

[0061] According to the embodiment of (4) above, by applying negative pressure to the membrane separation section via the condenser and buffer tank using a depressurizing pump, the separation of the first fluid in the membrane separation section can be suitably promoted. In this configuration, the depressurized first fluid is pressurized by a booster pump and supplied to the destination. The aforementioned concentration sensor uses the first fluid pressurized by such a booster pump as the target for concentration detection, thereby enabling the detection of the concentration of the first fluid separated in the membrane separation section with a simple configuration.

[0062] (5) In other embodiments, in any one embodiment of (1) to (4) above, the membrane separation unit includes a plurality of membrane separation modules connected in series with respect to the flow direction of the fluid to be treated, and capable of separating the fluid to be treated into the first fluid and the second fluid, respectively, using the separation membrane.

[0063] According to the embodiment of (5) above, by configuring the membrane separation unit to include a plurality of membrane separation modules, a membrane separation device capable of separating the first fluid and the second fluid from the fluid to be processed in multiple stages can be realized.

[0064] (6) In another embodiment, in the embodiment of (5) above, the device further includes a diagnostic unit for detecting the concentration while switching the open / closed state of a plurality of flows through which the first fluid separated in each of the plurality of membrane separation modules flows, when the flow path has been switched to the second flow path by the flow path switching unit, and for diagnosing abnormal locations from the plurality of membrane separation modules based on the result.

[0065] According to the embodiment of (6) above, when the concentration of the second fluid in the first fluid exceeds a reference value, the flow path is switched to the first flow path by the flow path switching unit, and the diagnostic unit diagnoses the abnormal location. The abnormal location is diagnosed by detecting the concentration of the first fluid separated in the membrane separation unit while switching the open / closed state of the flow path through which the first fluid separated in each membrane separation module flows. Although such diagnosis of abnormal locations takes a considerable amount of time, the flow path switching unit switches the flow path to the first flow path, which allows the membrane separation device to continue operating while stopping the supply of the first fluid to the supply destination, thus ensuring sufficient time for diagnosis.

[0066] (7) In another embodiment, in the embodiment of (5) above, the plurality of membrane isolation modules include at least one spare module that can be switched over with the membrane isolation module in which the malfunction has occurred.

[0067] According to the embodiment described in (7) above, good separation performance can be ensured by switching the malfunctioning membrane separation module with a backup module. The backup module requires a considerable amount of startup time to exhibit sufficient separation performance, but if a malfunction occurs in any of the membrane separation modules, the flow path is switched to the second flow path in the flow path switching unit, allowing the operation of the membrane separation apparatus to continue. By completing the startup operation of the backup module during this time, a smooth switch to the backup module can be achieved.

[0068] (8) In other embodiments, in any one embodiment of (1) to (7) above, the first fluid is a permeable fluid that permeates the separation membrane, and the second fluid is an impermeable fluid that does not permeate the separation membrane.

[0069] According to the embodiment of (8) above, a membrane separation device can be suitably realized that separates the fluid to be processed into a first fluid, which is a permeable fluid, and a second fluid, which is an impermeable fluid, by supplying the fluid to be processed to the separation membrane.

[0070] (9) A control method for a membrane separation apparatus according to one embodiment, comprising: a membrane separation unit for separating a fluid to be treated, purified in a distillation column, into a first fluid and a second fluid, which are different from each other, using a separation membrane; and a flow path switching unit that can selectively switch between a first flow path for supplying the first fluid to a destination, or a second flow path for returning the first fluid to the distillation column, as the flow path for the first fluid separated in the membrane separation unit, the control method for a membrane separation apparatus comprising: detecting the concentration of the second fluid in the first fluid separated in the membrane separation unit; and controlling the flow path switching unit to switch the flow path from the first flow path to the second flow path when the concentration becomes equal to or greater than a preset reference value.

[0071] According to the embodiment of (9) above, if the concentration of the second fluid in the first fluid separated in the membrane separation unit exceeds a reference value, the first fluid separated in the membrane separation unit is returned to the distillation column via the second flow path. This prevents the first fluid with a concentration above the reference value from being supplied to the recipient, while allowing the operation of the membrane separation apparatus to continue.

[0072] (10) In another embodiment, in the embodiment of (9) above, the membrane separation unit includes a plurality of membrane separation modules connected in series with respect to the flow direction of the fluid to be treated, and capable of separating the fluid to be treated into a first fluid and a second fluid, respectively, using the separation membrane, and further comprises the step of detecting the concentration while switching the open / closed state of a plurality of channels through which the first fluid separated in each of the plurality of membrane separation modules flows, and diagnosing abnormal locations from the plurality of membrane separation modules based on the result.

[0073] According to the embodiment of (10) above, when the concentration of the second fluid in the first fluid exceeds a reference value, the flow path is switched to the first flow path by the flow path switching unit, and the diagnostic unit diagnoses the abnormal location. The diagnosis of the abnormal location is performed by detecting the concentration of the first fluid separated in the membrane separation unit while switching the open / closed state of the flow path through which the first fluid separated in each membrane separation module flows. Although such diagnosis of abnormal locations takes a considerable amount of time, the flow path switching unit switches the flow path to the first flow path, which allows the membrane separation device to continue operating while stopping the supply of the first fluid to the supply destination, thus ensuring sufficient time for diagnosis.

[0074] (11) In another embodiment, in the embodiment of (9) above, the membrane separation unit includes a plurality of membrane separation modules connected in series with respect to the flow direction of the fluid to be processed, and capable of separating the fluid to be processed into a first fluid and a second fluid, respectively, using the separation membrane, the plurality of membrane separation modules include at least one spare module that can be switched over with the membrane separation module in which the malfunction has occurred, the step of starting up the spare module when the flow path is switched to the second flow path, the step of performing a switching operation between the malfunctioning membrane separation module and the spare module when the starting up operation is completed, and the step of switching the flow path from the second flow path to the first flow path.

[0075] According to the embodiment described in (11) above, good separation performance can be ensured by switching the malfunctioning membrane separation module with a backup module. The backup module requires a considerable amount of startup time to exhibit sufficient separation performance, but if a malfunction occurs in any of the membrane separation modules, the flow path is switched to the second flow path in the flow path switching unit, allowing the operation of the membrane separation apparatus to continue. By completing the startup operation of the backup module during this time, a smooth switch to the backup module can be achieved.

[0076] 1 Membrane separation apparatus 10 Fermentation tank 12 Distillation column 14 Condenser 17 Circulation pump 18 Primary tank 19 Pump 20 Secondary tank 21 Preheater 22 Membrane separation unit 24 Separation membrane 25 Membrane separation module 26 Container 27 Concentration sensor 28 Primary flow path 30 Secondary flow path 32 Primary inlet 34 Primary outlet 36 Secondary outlet 38 Confluence point 40 Flow path switching unit 41 Condenser 42 Buffer tank 44 Pressure reducing pump 46 Booster pump 50 Diagnostic unit 52 Analyzer 54a-54d Booster unit 100 Control device 110 Concentration detection unit 120 Flow path control unit Q0 Fluid to be processed Q1 First fluid Q2 Second fluid

Claims

1. A membrane separation apparatus comprising: a membrane separation unit for separating a fluid to be treated, purified in a distillation column, into two distinct fluids; a flow path switching unit capable of selectively switching between a first flow path for supplying the first fluid to a destination, or a second flow path for returning the first fluid to the distillation column, as the flow path for the first fluid separated in the membrane separation unit; and a concentration sensor for detecting the concentration of the second fluid in the first fluid separated in the membrane separation unit, wherein the flow path switching unit switches the flow path from the first flow path to the second flow path when the concentration detected by the concentration sensor exceeds a preset reference value.

2. The membrane separation apparatus according to claim 1, wherein the flow path switching unit is switched to select the first flow path as the flow path when the concentration detected by the concentration sensor is less than the reference value.

3. The membrane separation apparatus according to claim 1 or 2, wherein the flow path switching unit includes a first valve provided in the first flow path and a second valve provided in the second flow path, and the flow path can be switched by opening and closing the first valve and the second valve, respectively.

4. The membrane separation apparatus according to claim 1 or 2, comprising: a condenser for condensing the first fluid; a buffer tank for storing the first fluid condensed in the condenser; a depressurizing pump for applying negative pressure to the membrane separation unit via the condenser and the buffer tank; and a booster pump for pressurizing the first fluid stored in the buffer tank and supplying it to the supply destination, wherein the concentration sensor is provided to detect the concentration of the first fluid pressurized by the booster pump.

5. The membrane separation apparatus according to claim 1 or 2, wherein the membrane separation unit includes a plurality of membrane separation modules connected in series with respect to the flow direction of the fluid to be processed, and capable of separating the fluid to be processed into a first fluid and a second fluid, respectively, using the separation membrane.

6. The membrane separation apparatus according to claim 5, further comprising a diagnostic unit for detecting the concentration while switching the open / closed state of a plurality of channels through which the first fluid separated in each of the plurality of membrane separation modules flows, when the flow path has been switched to the second flow path by the flow path switching unit, and for diagnosing abnormal locations from the plurality of membrane separation modules based on the result.

7. The membrane separation apparatus according to claim 5, wherein the plurality of membrane separation modules include at least one spare module that can be switched over with the membrane separation module that has malfunctioned.

8. The membrane separation apparatus according to claim 1 or 2, wherein the first fluid is a permeable fluid that permeates the separation membrane, and the second fluid is an impermeable fluid that does not permeate the separation membrane.

9. A control method for a membrane separation apparatus comprising: a membrane separation unit for separating a fluid to be treated, purified in a distillation column, into two distinct fluids; and a flow path switching unit capable of selectively switching between a first flow path for supplying the first fluid to a destination, or a second flow path for returning the first fluid to the distillation column, the control method for a membrane separation apparatus comprising: detecting the concentration of the second fluid in the first fluid separated in the membrane separation unit; and controlling the flow path switching unit to switch the flow path from the first flow path to the second flow path when the concentration exceeds a preset reference value.

10. The control method for a membrane separation apparatus according to claim 9, wherein the membrane separation unit includes a plurality of membrane separation modules connected in series with respect to the flow direction of the fluid to be processed, and capable of separating the fluid to be processed into a first fluid and a second fluid, respectively, using the separation membrane, and further comprising the step of detecting the concentration while switching the open / closed state of a plurality of flow paths through which the first fluid separated in each of the plurality of membrane separation modules flows, when the flow path is switched to the second flow path, and diagnosing abnormal locations from the plurality of membrane separation modules based on the result.

11. The membrane separation unit includes a plurality of membrane separation modules connected in series with respect to the flow direction of the fluid to be processed, and capable of separating the fluid to be processed into a first fluid and a second fluid, respectively, using the separation membrane, wherein the plurality of membrane separation modules include at least one spare module that can be switched over with the membrane separation module in which an abnormality has occurred, and the control method for a membrane separation apparatus according to claim 9, comprising the steps of: starting the startup operation of the spare module when the flow path has been switched to the second flow path; performing a switching operation between the membrane separation module in which the abnormality occurred and the spare module when the startup operation is completed; and switching the flow path from the second flow path to the first flow path.

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