Membrane separation apparatus

Abstract

A membrane separation apparatus according to at least one embodiment of the present disclosure comprises: a module to be controlled, which is a separation membrane module having a separation membrane, a primary-side flow path, and a secondary-side flow path that is partitioned from the primary-side flow path by the separation membrane; a secondary-side pressure adjustment device for adjusting the pressure in the secondary-side flow path; and a control device. The control device is configured to: calculate, on the basis of detection results from a plurality of detection devices that are capable of detecting the states of a fluid being treated and a permeated fluid, the assumed flow rate of the permeated fluid under the assumption that the separation membrane has not deteriorated; and control the secondary-side pressure adjustment device so as to reduce the difference between the calculated assumed flow rate and the flow rate of the permeated fluid.

Description

Membrane separation device

[0001] The present disclosure relates to a membrane separation device. The present application claims priority based on Japanese Patent Application No. 2025-056153 filed with the Japan Patent Office on March 28, 2025, the content of which is incorporated herein by reference.

[0002] By using a separation membrane module having a separation membrane, some components are separated from a fluid containing a plurality of components (see, for example, Patent Document 1).

[0003] Japanese Patent No. 4929269

[0004] In a device configured to separate some components from a fluid containing a plurality of components by a separation membrane, the substantial membrane area (hereinafter also referred to as effective membrane area) decreases due to deterioration of the separation membrane caused by use. Among the primary side flow path and the secondary side flow path separated by the separation membrane, for example, when the fluid in the secondary side flow path that has permeated through the separation membrane contains components useful in subsequent processes such as product components (hereinafter also referred to as useful components), a decrease in the effective membrane area leads to a decrease in the recovery rate of the useful components. Further, for example, when the useful component is contained in the fluid of the primary side flow path, a decrease in the effective membrane area leads to a decrease in the purity of the useful component.

[0005] For this reason, the membrane area is sometimes set in anticipation of a decrease in the effective membrane area, but in the initial operation stage of the device, the membrane area tends to be excessive. When the membrane area is excessive relative to the required membrane area, there is an increased tendency for components that are not desired to permeate through the separation membrane to permeate through the separation membrane. Therefore, when the membrane area is excessive relative to the required membrane area, for example, when a useful component is contained in the fluid of the secondary side flow path that has permeated through the separation membrane, the purity of the useful component will decrease, and for example, when a useful component is contained in the fluid of the primary side flow path, the recovery rate of the useful component will decrease.

[0006] In view of the above circumstances, an object of at least one embodiment of the present disclosure is to provide a membrane separation device capable of reducing a decrease in the recovery rate and purity of components obtained in the membrane separation device.

[0007] A membrane separation apparatus according to at least one embodiment of the present disclosure comprises: a control module which is a separation membrane module having a separation membrane for separating a permeate fluid from a supplied fluid to be treated; a primary side flow path configured for the fluid to be treated to flow through; and a secondary side flow path separated from the primary side flow path by the separation membrane and configured for the permeate fluid that has permeated through the separation membrane to flow through; a plurality of detection devices capable of detecting the state of the fluid to be treated and the permeate fluid; a secondary side pressure regulating device for adjusting the pressure of the secondary side flow path; and a control device for controlling the secondary side pressure regulating device based on the detection results of the detection devices, wherein the control device is configured to calculate an assumed flow rate of the permeate fluid, which can be determined from the partial pressure or vapor pressure of the permeate target component in the fluid to be treated and the permeate fluid, assuming that the separation membrane is not deteriorated, based on the detection results of the detection devices, and to control the secondary side pressure regulating device to reduce the difference between the calculated assumed flow rate and the flow rate of the permeate fluid.

[0008] According to at least one embodiment of this disclosure, the recovery rate and purity of components obtained in a membrane separation apparatus can be reduced.

[0009] This is a diagram showing the overall configuration of the membrane separation apparatus according to the first embodiment. This is a diagram showing the overall configuration of the membrane separation apparatus according to the second embodiment. This is a diagram showing the overall configuration of the membrane separation apparatus according to the third embodiment. This is a diagram showing the overall configuration of the membrane separation apparatus according to the fourth embodiment.

[0010] Hereinafter, several embodiments of this disclosure will be described with reference to the attached drawings. However, the dimensions, materials, shapes, relative arrangements, etc., of the components described as embodiments or shown in the drawings are not intended to limit the scope of this disclosure, but are merely illustrative examples. For example, expressions describing relative or absolute arrangements such as "in a certain direction," "along a certain direction," "parallel," "orthogonal," "center," "concentric," or "coaxial" should not only describe such arrangements strictly, but also represent states of relative displacement with tolerances, or angles or distances to the extent that the same function is achieved. For example, expressions describing things being in an equal state such as "identical," "equal," and "homogeneous" should not only describe states of being strictly equal, but also represent states where tolerances, or differences to the extent that the same function is achieved, exist. For example, expressions describing shapes such as square shapes or cylindrical shapes should not only describe geometrically precise square shapes or cylindrical shapes, but also represent shapes including concave and concave parts, chamfered parts, etc., to the extent that the same effect is achieved. On the other hand, expressions such as "to possess," "to be equipped with," "to have," "to include," or "to have" a single component are not exclusive expressions that exclude the existence of other components.

[0011] Figure 1 shows the overall configuration of the membrane separation apparatus according to the first embodiment. Figure 2 shows the overall configuration of the membrane separation apparatus according to the second embodiment. Figure 3 shows the overall configuration of the membrane separation apparatus according to the third embodiment. Figure 4 shows the overall configuration of the membrane separation apparatus according to the fourth embodiment.

[0012] (Regarding configurations common to each embodiment) As shown in Figures 1 to 4, the membrane separation apparatus 1 according to some embodiments comprises a controlled module 3S which is a separation membrane module 3, a detection device 7, and a control device 9. The membrane separation apparatus 1 according to some embodiments comprises a secondary pressure regulating device 50 and a temperature regulating device 55. The membrane separation apparatus 1 according to some embodiments is connected to a fluid to be processed supply channel 21 for supplying a fluid to be processed F1 to the membrane separation apparatus 1. The membrane separation apparatus 1 according to some embodiments comprises a fluid to be processed discharge channel 22 for discharging the fluid to be processed F1 from the primary side channel 13 of the controlled module 3S (described later) to the outside (outside the system) of the membrane separation apparatus 1, and a permeate fluid discharge channel 23 for discharging the permeate fluid F2 from the secondary side channel 15 of the controlled module 3S (described later) to the outside (outside the system) of the membrane separation apparatus 1.

[0013] (Separation Membrane Module 3) In some embodiments of the membrane separation apparatus 1, the separation membrane module 3 includes a separation membrane 11 for separating a permeate fluid F2 from a supplied fluid to be processed F1, a primary side flow path 13 configured for the flow of the fluid to be processed F1, and a secondary side flow path 15 separated from the primary side flow path 13 by the separation membrane 11 and configured for the flow of the permeate fluid F2 that has permeated through the separation membrane 11. The separation membrane module 3 includes a primary side inlet 13i which is the inlet for the fluid to be processed F1 to the primary side flow path 13, a primary side outlet 13o which is the outlet for the fluid to be processed F1 after it has flowed through the primary side flow path 13, and a secondary side outlet 15o which is the outlet for the permeate fluid F2 from the secondary side flow path 15.

[0014] (Detection device 7) In several embodiment membrane separation apparatus 1, the detection device 7 is a detection device capable of detecting the state of the fluid to be processed F1 and the permeate fluid F2, and includes a primary flow rate detection device 71, a primary concentration detection device 72, a secondary flow rate detection device 73, a secondary concentration detection device 74, a primary pressure detection device 75, a secondary pressure detection device 76, a fluid to be processed temperature detection device 77, and a primary concentration detection device 78. The detection results of the detection device 7 are output to the control device 9, which will be described later.

[0015] The primary flow detection device 71 is a sensor for detecting the flow rate of the fluid to be treated F1 after it has flowed through the separation membrane module 3. As will be described later, when multiple separation membrane modules 3 are arranged in the membrane separation device 1, the primary flow detection device 71 is positioned downstream of the fluid to be treated outlet channel 22 so as to be able to detect the flow rate of the fluid to be treated F1 after it has flowed through all the arranged separation membrane modules 3. The primary concentration detection device 72 is a sensor for detecting the concentration of the target component in the fluid to be treated F1 after it has flowed through the separation membrane module 3. As will be described later, when multiple separation membrane modules 3 are arranged in the membrane separation device 1, the primary flow detection device 71 is positioned downstream of the fluid to be treated outlet channel 22 so as to be able to detect the concentration of the target component in the fluid to be treated F1 after it has flowed through all the arranged separation membrane modules 3.

[0016] The secondary flow rate detection device 73 is a sensor for detecting the flow rate of the permeate fluid F2 from the secondary flow path 15. When multiple separation membrane modules 3 are arranged in the membrane separation device 1 as described later, the secondary flow rate detection device 73 is located downstream of the permeate fluid outlet channel 23 so that the flow rate of the permeate fluid F2 from all of the separation membrane modules 3 can be detected. The secondary concentration detection device 74 is a sensor for detecting the concentration of the target component in the permeate fluid F2 from the secondary flow path 15. When multiple separation membrane modules 3 are arranged in the membrane separation device 1 as described later, the secondary concentration detection device 74 is located downstream of the permeate fluid outlet channel 23 so that the concentration of the target component in the permeate fluid F2 from all of the separation membrane modules 3 can be detected.

[0017] The primary pressure detection device 75 is a sensor for detecting the pressure in the primary flow path 13 of the controlled module 3S. The secondary pressure detection device 76 is a sensor for detecting the pressure in the secondary flow path 15 of the controlled module 3S. The processed fluid temperature detection device 77 is a sensor for detecting the temperature of the processed fluid F1 supplied to the primary flow path 13 of the controlled module 3S. The primary concentration detection device 78 is a sensor for detecting the concentration of the target component in the processed fluid F1 supplied to the primary flow path 13 of the controlled module 3S.

[0018] (Secondary Pressure Regulator 50) In several embodiments of the membrane separation apparatus 1, the secondary pressure regulator 50 is a device for regulating the pressure of the secondary flow path 15 of the controlled module 3S. The secondary pressure regulator 50 includes a flow control valve 51 for regulating the flow rate of the permeate fluid F2 flowing from the secondary flow path 15 toward the permeate fluid outlet flow path 23, and a booster 52 configured to draw in the permeate fluid F2 from the secondary flow path 15 and discharge it to the permeate fluid outlet flow path 23. The flow control valve 51 and the booster 52 are configured to be controlled by a control device 9, which will be described later.

[0019] (Temperature control device 55) In some embodiments of the membrane separation apparatus 1, the temperature control device 55 is a device for adjusting the temperature of the fluid to be processed F1 supplied to the primary flow path 13 of the module to be controlled 3S, and is, for example, a heat exchanger configured to change the temperature of the fluid to be processed F1 supplied to the primary flow path 13 by the control device 9.

[0020] (Control device 9) In some embodiments of the membrane separation apparatus 1, the control device 9 is a device for controlling the secondary pressure regulator 50 based on the detection result of the detection device 7. The control device 9 is composed 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, and the CPU reads this program into the RAM and executes information processing and calculations to realize 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 means. Computer-readable storage media include magnetic disks, magneto-optical disks, CD-ROMs, DVD-ROMs, semiconductor memory, etc. The control details of each part of the membrane separation apparatus 1 by the control device 9 will be explained later.

[0021] (Regarding the amount of permeation of the target component in the separation membrane) The amount of permeation of the target component in the separation membrane will be explained below. The amount of permeation Qx of the target component in the separation membrane can be determined by the following equation (1) or (2). Note that equation (1) is for membrane separation by the VP method (VP: Vapor permeation), and equation (2) is for membrane separation by the PV method (PV: Pervaporation). Qx = f・kx・(px1-px2)・A ... (1) Qx = f・kx・(p ＊ x-px2)・A...(2)

[0022] The coefficients and parameters in equations (1) and (2) are as follows: kx: transmission coefficient of the target component x [kg / (m) ２ Qx: Permeation rate of the permeation target component x [kg / h] px1: Primary side (non-permeation side) partial pressure of the permeation target component x [kPa] px2: Secondary side (permeation side) partial pressure of the permeation target component x [kPa] p ＊x: Primary saturated vapor pressure of the target component x [kPa] A: Membrane area of ​​the separation membrane [m²] ２ ] f: Degradation coefficient of the separation membrane [-]

[0023] The degradation coefficient f of the separation membrane is a dimensionless coefficient with the degradation coefficient f of an unused separation membrane set to 1. As the separation membrane deteriorates through use, its value gradually decreases from 1.

[0024] In a device configured to separate some components from a fluid containing multiple components using a separation membrane, as the separation membrane deteriorates with use, the deterioration coefficient f decreases, resulting in a decrease in the amount Qx of the target component that permeates through the separation membrane. In other words, as the separation membrane deteriorates with use, the effective membrane area (hereinafter also referred to as the effective membrane area) decreases due to the deterioration of the separation membrane. Here, the effective membrane area corresponds to the product of the membrane area A of the separation membrane and the deterioration coefficient f of the separation membrane (f・A).

[0025] (Regarding the effects of deterioration of the separation membrane 11 and countermeasures) In the membrane separation apparatus 1 according to several embodiments, if the fluid in the secondary channel 15 that has permeated through the separation membrane 11 contains components of the product or other components useful in later processes (hereinafter also referred to as useful components), the recovery rate of the useful components will decrease if the separation membrane 11 deteriorates. Also, if the fluid in the primary channel 13 contains useful components, the purity of the useful components will decrease if the separation membrane 11 deteriorates.

[0026] Therefore, in some embodiments of the membrane separation apparatus 1, when the deterioration of the separation membrane 11 progresses to a certain extent, the pressure in the secondary flow path 15 in the controlled module 3S is lowered, as described below, thereby lowering the secondary partial pressure px2 of the permeate target component x and increasing the amount Qx of the permeate target component x.

[0027] The control device 9 calculates the primary side partial pressure px1 of the permeate target component x based on the pressure of the primary side flow path 13 in the controlled module 3S detected by the primary side pressure detection device 75 and the concentration of the target component in the fluid to be treated F1 supplied to the primary side flow path 13 of the controlled module 3S detected by the primary side concentration detection device 78. Alternatively, the control device 9 calculates the primary side saturated vapor pressure p of the permeate target component x based on the pressure of the primary side flow path 13 in the controlled module 3S detected by the primary side pressure detection device 75, the concentration of the target component in the fluid to be treated F1 supplied to the primary side flow path 13 of the controlled module 3S detected by the primary side concentration detection device 78 and the temperature of the fluid to be treated F1 supplied to the primary side flow path 13 of the controlled module 3S detected by the fluid to be treated temperature detection device 77. ＊ x is calculated. The control device 9 calculates the secondary partial pressure px2 of the permeate target component x based on the pressure of the secondary flow path 15 in the controlled module 3S detected by the secondary pressure detection device 76 and the concentration of the target component in the permeate fluid F2 from the secondary flow path 15 detected by the secondary concentration detection device 74 (in the case of Figures 1 and 3) or the secondary concentration detection device 79 (in the case of Figures 2 and 4) to be described later. The control device 9 then reads the permeation coefficient kx of the permeate target component x, the membrane area A of the separation membrane 11 and the above equation (1) or (2) stored in the memory of the control device 9 (not shown), calculates the amount of permeate target component x Qx when the degradation coefficient f of the separation membrane 11 is 1, and sets the calculated amount of permeate Qx as the assumed flow rate Qx0 of the permeate fluid F2 when it is assumed that the separation membrane has not deteriorated.

[0028] Next, the control device 9 compares the assumed flow rate Qx0 with the flow rate of the permeating fluid F2 from the secondary flow path 15 of the controlled module 3S, as detected by the secondary flow rate detection device 73.

[0029] If the flow rate of the permeating fluid F2 from the secondary flow path 15 of the controlled module 3S, as detected by the secondary flow rate detection device 73, is less than the assumed flow rate Qx0, the control device 9 controls the secondary pressure regulator 50 to lower the pressure in the secondary flow path 15. That is, the control device 9 activates the booster 52 to draw in the permeating fluid F2 from the secondary flow path 15 of the controlled module 3S. As a result, the pressure in the secondary flow path 15 in the controlled module 3S decreases, the secondary partial pressure px2 of the permeating component x decreases, and the amount of permeating component x Qx increases, so the flow rate of the permeating fluid F2 from the secondary flow path 15 of the controlled module 3S increases. Therefore, the effect of the decrease in effective membrane area due to the deterioration of the separation membrane 11 can be reduced.

[0030] Furthermore, if the flow rate of the permeating fluid F2 from the secondary flow path 15 of the controlled module 3S, as detected by the secondary flow rate detection device 73, is greater than the assumed flow rate Qx0, the control device 9 may control the secondary pressure regulator 50 to increase the pressure in the secondary flow path 15. In this case, the control device 9 controls the flow control valve 51 to narrow its opening. As a result, the pressure in the secondary flow path 15 of the controlled module 3S increases, the secondary partial pressure px2 of the permeating component x increases, and the permeation amount Qx of the permeating component x decreases, thus reducing the flow rate of the permeating fluid F2 from the secondary flow path 15 of the controlled module 3S. Therefore, even if the membrane area A is excessive, as will be described later, the effects of the excessive membrane area A can be reduced.

[0031] In the membrane separation apparatus 1 according to several embodiments described above, the control device 9 is configured to control the secondary pressure regulator 50 so as to reduce the difference between the assumed flow rate Qx0 and the flow rate of the permeate fluid F2 from the secondary flow path 15 of the module to be controlled 3S.

[0032] (Regarding the effects of excessive membrane area A of the separation membrane 11 and countermeasures) If the membrane area A of the controlled module 3S is set anticipating the deterioration of the separation membrane 11 as described above, the membrane area A will be excessive in the initial stages of operation of the membrane separation device 1. When the membrane area A is excessive compared to the required membrane area A, there is a higher tendency for components that are not desired to permeate the separation membrane 11 to permeate the separation membrane 11. Therefore, if the membrane area A is excessive compared to the required membrane area A, for example, if the permeate fluid F2 in the secondary flow path 15 that has permeated through the separation membrane 11 contains useful components, the purity of the useful components will decrease, and for example, if the fluid to be processed F1 in the primary flow path 13 contains useful components, the recovery rate of the useful components will decrease. In this case, a decrease in the concentration of useful components in the permeate fluid F2 detected by the secondary concentration detection device 74 and a decrease in the flow rate of the fluid to be processed F1 detected by the primary flow rate detection device 71 will occur.

[0033] Therefore, in some embodiments of the membrane separation apparatus 1, if the membrane area A of the separation membrane 11 is excessive, the pressure of the secondary flow path 15 in the controlled module 3S may be increased to raise the secondary partial pressure px2 of the permeate target component x, thereby reducing the amount Qx of the permeate target component x, as described below.

[0034] In other words, if the flow rate of the fluid to be processed F1 detected by the primary flow rate detection device 71 is below a specified flow rate, or if the concentration of the target component in the permeate fluid F2 detected by the secondary concentration detection device 74 is below a specified concentration, the control device 9 may control the secondary pressure regulator 50 to increase the pressure in the secondary flow path 15 of the controlled module 3S. That is, the control device 9 controls the flow control valve 51 to narrow the opening of the flow control valve 51. As a result, the pressure in the secondary flow path 15 of the controlled module 3S increases, the secondary partial pressure px2 of the target component x increases, and the amount of permeate Qx of the target component x decreases, so the flow rate of the permeate fluid F2 from the secondary flow path 15 of the controlled module 3S decreases. Therefore, the effect of an excessive film area A can be reduced.

[0035] (Regarding the effect of the temperature of the fluid to be processed F1) The permeation coefficient kx in equations (1) and (2) above increases when the temperature of the fluid to be processed F1 rises and decreases when the temperature of the fluid to be processed F1 falls. Therefore, in the membrane separation apparatus 1 according to some embodiments, the control device 9 may correct the permeation coefficient kx based on the temperature of the fluid to be processed F1 supplied to the primary flow path 13 of the controlled module 3S, as detected by the fluid to be processed temperature detection device 77. That is, in the membrane separation apparatus 1 according to some embodiments, the control device 9 may correct the permeation coefficient kx based on the temperature of the fluid to be processed F1 supplied to the primary flow path 13 of the controlled module 3S, as detected by the fluid to be processed temperature detection device 77, and then calculate the assumed flow rate Qx0 as described above. By calculating the assumed flow rate Qx0 considering the temperature of the fluid to be processed F1 in this way, the accuracy of calculating the assumed flow rate Qx0 can be improved. As a result, the effect of the decrease in effective membrane area due to the deterioration of the separation membrane 11 and the effect of the excessive membrane area A can be reduced with relatively high accuracy.

[0036] Furthermore, in some embodiments of the membrane separation apparatus 1, when the deterioration of the separation membrane 11 progresses to a certain extent, the temperature of the fluid to be processed F1 supplied to the primary side flow path 13 of the controlled module 3S is increased to increase the permeation coefficient kx, and when equation (2) is applied, the primary side saturated vapor pressure p of the permeation target component x is also increased. ＊ The amount of permeation Qx of the permeation target component x may be increased by increasing x. That is, in addition to the control of the secondary flow path 15 by the booster 52 as described above, the control device 9 may also increase the temperature of the fluid to be processed F1 supplied to the primary flow path 13 of the controlled module 3S by controlling the temperature control device 55. By adjusting the temperature of the fluid to be processed F1 supplied to the primary flow path 13 of the controlled module 3S in this way, the effect of the decrease in effective membrane area due to the deterioration of the separation membrane 11 can be reduced.

[0037] In some embodiments of the membrane separation apparatus 1, if the membrane area A of the separation membrane 11 is excessive, the permeation coefficient kx is reduced by lowering the temperature of the fluid to be processed F1 supplied to the primary side flow path 13 of the controlled module 3S, and further, when equation (2) is applied, the primary side saturated vapor pressure p of the permeation target component x is reduced. ＊ The amount of permeation Qx of the permeation target component x may be reduced by lowering x. That is, in addition to the control that increases the pressure in the secondary flow path 15 by narrowing the opening of the flow control valve 51 as described above, the control device 9 may also lower the temperature of the fluid to be treated F1 supplied to the primary flow path 13 of the controlled module 3S by controlling the temperature control device 55. In this way, the effect of excessive film area can also be reduced by adjusting the temperature of the fluid to be treated F1 supplied to the primary flow path 13 of the controlled module 3S.

[0038] (Regarding the second embodiment) For example, consider the case where the primary flow paths 13 of two separation membrane modules 3 are connected in series, as shown in Figure 2. The membrane separation apparatus 1 according to the second embodiment shown in Figure 2 has, in addition to the configuration of the membrane separation apparatus 1 according to the first embodiment shown in Figure 1, an upstream separation membrane module 3F, which is the same separation membrane module 3 as the controlled module 3S, located upstream of the controlled module 3S. In the membrane separation apparatus 1 according to the second embodiment, the primary outlet portion 13o of the upstream separation membrane module 3F is connected to the primary inlet portion 13i of the controlled module 3S via a flow path 24. In the membrane separation apparatus 1 according to the second embodiment, the temperature control device 55 is provided in the middle of the flow path 24. The secondary outlet portion 15o of the secondary flow path 15 of the upstream separation membrane module 3F is in communication with the permeate fluid outlet flow path 23.

[0039] In the membrane separation apparatus 1 according to the second embodiment, the detection device 7 further includes a primary side pressure detection device 82, a fluid temperature detection device 83, a primary side concentration detection device 84, and a secondary side concentration detection device 79.

[0040] The primary-side pressure detector 82 is a sensor for detecting the pressure of the primary-side flow path 13 in the upstream separation membrane module 3F. The fluid-to-be-treated temperature detector 83 is a sensor for detecting the temperature of the fluid to be treated F1 supplied to the primary-side flow path 13 of the upstream separation membrane module 3F. The primary-side concentration detector 84 is a sensor for detecting the concentration of the measurement target component in the fluid to be treated F1 supplied to the primary-side flow path 13 of the upstream separation membrane module 3F. The secondary-side concentration detector 79 is a sensor for detecting the concentration of the measurement target component in the permeated fluid F2 from the secondary-side flow path 15 of the control target module 3S.

[0041] In a case where the upstream separation membrane module 3F, which is the separation membrane module 3, is provided upstream of the control target module 3S in anticipation of the deterioration of the separation membrane 11 as described above, the membrane area A becomes excessive in the initial operation stage of the membrane separation device 1.

[0042] Therefore, in the membrane separation device 1 according to the second embodiment, when the membrane area A of the separation membrane 11 is excessive, similar to the first embodiment described above, the secondary partial pressure px2 of the permeation target component x is increased by increasing the pressure of the secondary-side flow path 15 in the control target module 3S, so as to reduce the permeation amount Qx of the permeation target component x.

[0043] That is, when the flow rate of the fluid to be treated F1 detected by the primary-side flow rate detector 71 is equal to or lower than a specified flow rate, or when the concentration of the measurement target component in the permeated fluid F2 detected by the secondary-side concentration detector 79 is equal to or lower than a specified concentration, the control device 9 controls the secondary-side pressure adjusting device 50 to increase the pressure of the secondary-side flow path 15 of the control target module 3S. That is, the control device 9 controls the flow control valve 51 to reduce the opening degree of the flow control valve 51. As a result, the pressure of the secondary-side flow path 15 in the control target module 3S increases, so the secondary partial pressure px2 of the permeation target component x increases, and the permeation amount Qx of the permeation target component x decreases. Therefore, the influence caused by the excessive membrane area A can be reduced.

[0044] Incidentally, when the flow rate of the fluid to be treated F1 detected by the primary-side flow rate detection device 71 is equal to or less than a specified flow rate, or when the concentration of the measurement target component in the permeated fluid F2 detected by the secondary-side concentration detection device 79 is equal to or less than a specified concentration, the control device 9 may lower the temperature by controlling the temperature adjustment device 55 so as to lower the temperature of the fluid to be treated F1 supplied to the primary-side flow path 13 of the control target module 3S as described above.

[0045] Incidentally, also in the membrane separation device 1 according to the second embodiment, deterioration of the separation membrane 11 progresses. Therefore, in the membrane separation device 1 according to the second embodiment, when the deterioration of the separation membrane 11 progresses to a certain extent, similarly to the first embodiment described above, the secondary partial pressure px2 of the permeation target component x is lowered by lowering the pressure of the secondary-side flow path 15 in the control target module 3S, thereby increasing the permeation amount Qx of the permeation target component x.

[0046] In the membrane separation device 1 according to the second embodiment, the total flow rate Qt of the permeated fluid F2 led out from the permeated fluid lead-out flow path 23 to the outside (outside the system) of the membrane separation device 1 is the sum of the permeated fluids F2 from all the separation membrane modules 3, and is represented by the following formula (3). Qt=fa·kx·(px1a−px2a)·A +fb·kx·(px1b−px2b)·A···(3) The coefficients and parameters in formula (3) are as follows. px1a: Primary-side (non-permeation side) partial pressure [kPa] of the permeation target component x in the upstream separation membrane module 3F px2a: Secondary-side (permeation side) partial pressure [kPa] of the permeation target component x in the upstream separation membrane module 3F px1b: Primary-side (non-permeation side) partial pressure [kPa] of the permeation target component x in the control target module 3S px2b: Secondary-side (permeation side) partial pressure [kPa] of the permeation target component x in the control target module 3S fa: Deterioration coefficient [-] of the separation membrane in the upstream separation membrane module 3F fb: Deterioration coefficient [-] of the separation membrane in the control target module 3S

[0047] As the separation membrane 11 in the upstream separation membrane module 3F and the controlled module 3S deteriorates, the deterioration coefficients fa and fb of the separation membrane decrease, and the total flow rate Qt of the permeate fluid F2 decreases. In the membrane separation apparatus 1 according to the second embodiment, when the deterioration of the separation membrane 11 progresses to a certain extent, the pressure in the secondary flow path 15 in the controlled module 3S is lowered, similar to the first embodiment described above, to lower the secondary partial pressure px2 of the permeate target component x, thereby increasing the total flow rate Qt of the permeate fluid F2. For example, the control device 9 calculates the assumed flow rate Qx0a of the permeate fluid F2 in the upstream separation membrane module 3F when the deterioration coefficient fa is 1, and the assumed flow rate Qx0b of the permeate fluid F2 in the controlled module 3S when the deterioration coefficient fb is 1, as described above. Next, the control device 9 compares the sum of the assumed flow rate Qx0a and the assumed flow rate Qx0b (Qx0a + Qx0b) with the total flow rate Qt of the permeate fluid F2 detected by the secondary flow rate detection device 73.

[0048] If the total flow rate Qt of the permeate fluid F2 detected by the secondary flow rate detection device 73 is less than the sum of the assumed flow rate Qx0a and the assumed flow rate Qx0b (Qx0a + Qx0b), the control device 9 controls the secondary pressure regulator 50 to lower the pressure in the secondary flow path 15 of the controlled module 3S.

[0049] Furthermore, if the total flow rate Qt of the permeate fluid F2 detected by the secondary flow rate detection device 73 is less than the sum of the assumed flow rate Qx0a and the assumed flow rate Qx0b (Qx0a + Qx0b), the control device 9 may lower the temperature of the fluid to be processed F1 supplied to the primary flow path 13 of the controlled module 3S by controlling the temperature control device 55 as described above.

[0050] In the membrane separation apparatus 1 according to several embodiments described above, the control device 9 is configured to control the secondary pressure regulating device 50 so as to reduce the difference between the sum of the assumed flow rate Qx0a and the assumed flow rate Qx0b (Qx0a + Qx0b) and the total flow rate Qt of the permeate fluid F2.

[0051] (Regarding the third embodiment) In the membrane separation apparatus 1 according to the third embodiment shown in Figure 3, in addition to the configuration of the membrane separation apparatus 1 according to the first embodiment shown in Figure 1, an external fluid supply channel 61 is provided for guiding fluid from outside the system to the secondary flow channel 15 of the controlled module 3S. In the membrane separation apparatus 1 according to the third embodiment, fluid from outside the membrane separation apparatus 1 can be supplied to the secondary flow channel 15 of the controlled module 3S via the external fluid supply channel 61. This makes it possible to lower the partial pressure of the components that have permeated through the separation membrane 11 in the secondary flow channel 15 and increase the amount of components that permeate through the separation membrane 11. As a result, for example, if the fluid in the primary flow channel 13 contains useful components, the purity of the useful components can be improved. Also, for example, if the fluid in the secondary flow channel 15 that has permeated through the separation membrane 11 contains useful components, the recovery rate of the useful components can be improved.

[0052] (Regarding the fourth embodiment) The membrane separation apparatus 1 according to the fourth embodiment shown in Figure 4, in addition to the configuration of the membrane separation apparatus 1 according to the second embodiment shown in Figure 2, is provided with a flow path 63 that connects the outlet of the booster 52 to the permeate fluid outlet flow path 23 and a connecting flow path 62 that connects the secondary flow path 15 of the upstream separation membrane module 3F.

[0053] In the membrane separation apparatus 1 according to the fourth embodiment, the partial pressure in the secondary channel 15 of the controlled module 3S of the component that has permeated through the separation membrane 11 is lower than the partial pressure in the secondary channel 15 of the upstream separation membrane module 3F of the component that has permeated through the separation membrane 11. According to the membrane separation apparatus 1 according to the fourth embodiment, by introducing a portion of the permeate fluid F2 in the secondary channel 15 of the controlled module 3S into the secondary channel 15 of the upstream separation membrane module 3F via the connecting channel 62, the partial pressure in the secondary channel 15 of the upstream separation membrane module 3F of the component that has permeated through the separation membrane 11 can be reduced, and the amount of the component that permeates through the separation membrane 11 can be increased. In the example shown in Figure 4, a portion of the permeate fluid F2 in the secondary channel 15 of the controlled module 3S is introduced into the secondary channel 15 of the upstream separation membrane module 3F via the connecting channel 62. However, the entire amount of permeate fluid F2 in the secondary channel 15 of the controlled module 3S may also be introduced into the secondary channel 15 of the upstream separation membrane module 3F via the connecting channel 62.

[0054] This disclosure is not limited to the embodiments described above, but also includes modified forms of the embodiments described above, and forms that combine these forms as appropriate. That is, the second embodiment described above may be combined with at least one of the third embodiment and the fourth embodiment described above. Similarly, the third embodiment described above may be combined with at least one of the second embodiment and the fourth embodiment described above. The fourth embodiment described above may be combined with at least one of the second embodiment and the third embodiment described above.

[0055] The contents described in each of the above embodiments can be understood, for example, as follows: (1) A membrane separation apparatus 1 according to at least one embodiment of the present disclosure comprises a separation membrane module 3S having a separation membrane 11 for separating a permeate fluid F2 from a supplied fluid to be processed F1, a primary side flow path 13 configured for the flow of the fluid to be processed F1, and a secondary side flow path 15 separated from the primary side flow path 13 by the separation membrane 11 and configured for the flow of the permeate fluid F2 that has permeated through the separation membrane 11, a plurality of detection devices 7 capable of detecting the state of the fluid to be processed F1 and the permeate fluid F2, a secondary side pressure adjustment device 50 for adjusting the pressure of the secondary side flow path 15, and a control device 9 for controlling the secondary side pressure adjustment device 50 based on the detection results of the detection devices 7. The control device 9 is configured to calculate an assumed flow rate Qx0 of the permeate fluid F2, which can be determined from the partial pressure or vapor pressure of the fluid to be processed F1 and the permeate fluid F2 containing the components to be permeated through the separation membrane 11, based on the detection results of the detection device 7, assuming that the separation membrane 11 is not deteriorated, and to control the secondary pressure regulator 50 to minimize the difference between the calculated assumed flow rate Qx0 and the flow rate of the permeate fluid F2.

[0056] According to the configuration described in (1) above, the effects of the decrease in effective membrane area due to the deterioration of the separation membrane 11, and the effects of an excessive membrane area can be reduced.

[0057] (2) In some embodiments, in the configuration of (1) above, the detection device 7 may include a fluid temperature detection device 77 for detecting the temperature of the fluid to be treated F1 supplied to the primary flow path 13. The control device 9 may calculate the assumed flow rate Qx0 considering the temperature of the fluid to be treated F1 detected by the fluid temperature detection device 77.

[0058] According to the configuration in (2) above, the accuracy of calculating the assumed flow rate Qx0 can be improved by considering the temperature of the fluid to be processed F1 supplied to the primary flow path 13. This makes it possible to reduce the effects of the decrease in effective membrane area due to the deterioration of the separation membrane 11, as well as the effects of an excessive membrane area, with relatively good accuracy.

[0059] (3) In some embodiments, the configuration of (2) above may include a temperature control device 55 for adjusting the temperature of the fluid to be treated F1 supplied to the primary side flow path 13. The control device 9 may be configured to control the temperature control device 55 so as to change the temperature of the fluid to be treated F1 supplied to the primary side flow path 13 so as to reduce the difference between the assumed flow rate Qx0 and the flow rate of the permeate fluid F2.

[0060] According to the configuration described in (3) above, the effects of the decrease in effective membrane area due to the deterioration of the separation membrane 11, as well as the effects of an excessive membrane area, can be reduced by adjusting the temperature of the fluid to be processed F1 supplied to the primary flow path 13.

[0061] (4) In some embodiments, the configuration of (1) to (3) above may include a primary flow rate detection device 71 for detecting the flow rate of the fluid to be treated F1 after it has flowed through the controlled module 3S, and a secondary concentration detection device (secondary concentration detection device 74 in the first and third embodiments, or secondary concentration detection device 79 in the second and fourth embodiments) for detecting the concentration of the target component in the permeate fluid F2 from the controlled module 3S. The control device 9 may control the secondary pressure regulator 50 to increase the pressure in the secondary flow path 15 if the flow rate of the fluid to be treated F1 detected by the primary flow rate detection device 71 is less than or equal to a specified flow rate, or if the concentration of the target component in the permeate fluid F2 detected by the secondary concentration detection device (secondary concentration detection device 74 in the first and third embodiments, or secondary concentration detection device 79 in the second and fourth embodiments) is less than or equal to a specified concentration.

[0062] According to the configuration described in (4) above, the effects of excessive film area can be reduced.

[0063] (5) In some embodiments, the configuration of (1) to (4) above may include an upstream separation membrane module 3F, which is different from the controlled module 3S, having a separation membrane 11, a primary side flow path 13, and a secondary side flow path 15. The primary side flow path 13 of the upstream separation membrane module 3F is preferably connected in series downstream of the primary side flow path 13 of the controlled module 3S in the flow of the fluid to be processed F1.

[0064] According to the configuration in (5) above, by adjusting the pressure in the secondary flow path 15 of the controlled module 3S, the effect of at least one of the following can be reduced: the effect of a decrease in effective membrane area due to deterioration of the separation membrane 11 of the upstream separation membrane module 3F and the controlled module 3S, or the effect of an excessive membrane area of ​​the upstream separation membrane module 3F and the controlled module 3S.

[0065] (6) In some embodiments, the configuration of (5) above may include a discharge channel (permeate outlet channel 23) for guiding the permeate fluid F2 in the secondary channel 15 of the upstream separation membrane module 3F to the outside of the system, and a connecting channel 62 for connecting the secondary channel 15 of the upstream separation membrane module 3F and the secondary channel 15 of the controlled module 3S.

[0066] In the configuration of (6) above, the partial pressure in the secondary channel 15 of the controlled module 3S of the component that has permeated through the separation membrane 11 is lower than the partial pressure in the secondary channel 15 of the upstream separation membrane module 3F of the component that has permeated through the separation membrane 11. According to the configuration of (6) above, by introducing the permeate fluid F2 in the secondary channel 15 of the controlled module 3S into the secondary channel 15 of the upstream separation membrane module 3F via the connecting channel 62, the partial pressure in the secondary channel 15 of the upstream separation membrane module 3F of the component that has permeated through the separation membrane 11 can be reduced, and the amount of the component that permeates through the separation membrane 11 can be increased.

[0067] (7) In some embodiments, in any of the configurations (1) to (5) above, the controlled module 3S may have a supply channel (external fluid supply channel 61) connected to the secondary channel 15 for introducing fluid from outside the system.

[0068] According to the configuration described in (7) above, by introducing fluid from outside the system into the secondary channel 15 of the controlled module 3S, the partial pressure of the components that have permeated through the separation membrane 11 in the secondary channel 15 can be reduced, thereby increasing the amount of components that permeate through the separation membrane 11. As a result, for example, if the fluid in the primary channel 13 contains useful components, the purity of the useful components can be improved. Also, for example, if the fluid in the secondary channel 15 that has permeated through the separation membrane 11 contains useful components, the recovery rate of the useful components can be improved.

[0069] 1 Membrane separation device 3 Separation membrane module 3F Upstream separation membrane module 3S Controlled module 7 Detection device 9 Control device 11 Separation membrane 13 Primary flow path 15 Secondary flow path 21 Fluid to be processed supply flow path 22 Fluid to be processed outlet flow path 23 Permeate fluid outlet flow path 24 Flow path 50 Secondary pressure regulator 51 Flow control valve 52 Pressure booster 55 Temperature regulator 61 External fluid supply flow path 62 Connecting flow path 71 Primary flow detection device 72 Primary concentration detection device 73 Secondary flow detection device 74 Secondary concentration detection device 75 Primary pressure detection device 76 Secondary pressure detection device 77 Fluid to be processed temperature detection device 79 Secondary concentration detection device

Claims

1. A membrane separation device comprising: a control module which is a separation membrane module having a separation membrane for separating a permeate fluid from a supplied fluid to be treated, a primary side flow path configured for the fluid to be treated to flow through, and a secondary side flow path separated from the primary side flow path by the separation membrane and configured for the permeate fluid that has permeated through the separation membrane to flow through; a plurality of detection devices capable of detecting the state of the fluid to be treated and the permeate fluid; a secondary side pressure regulating device for adjusting the pressure of the secondary side flow path; and a control device for controlling the secondary side pressure regulating device based on the detection results of the detection devices, wherein the control device is configured to calculate an assumed flow rate of the permeate fluid, which can be determined from the partial pressure or vapor pressure of the permeate target component in the fluid to be treated and the permeate fluid, assuming that the separation membrane is not deteriorated, based on the detection results of the detection devices, and to control the secondary side pressure regulating device to reduce the difference between the calculated assumed flow rate and the flow rate of the permeate fluid.

2. The membrane separation apparatus according to claim 1, wherein the detection device includes a fluid to be treated temperature detection device for detecting the temperature of the fluid to be treated supplied to the primary side flow path, and the control device calculates the assumed flow rate taking into account the temperature of the fluid to be treated detected by the fluid to be treated temperature detection device.

3. A membrane separation apparatus according to claim 2, comprising a temperature control device for adjusting the temperature of the fluid to be treated supplied to the primary side flow path, wherein the control device is configured to control the temperature control device so as to change the temperature of the fluid to be treated supplied to the primary side flow path so as to reduce the difference between the assumed flow rate and the flow rate of the permeate fluid.

4. A membrane separation apparatus according to any one of claims 1 to 3, comprising: a primary flow rate detection device for detecting the flow rate of the fluid to be processed after it has flowed through the controlled module; and a secondary concentration detection device for detecting the concentration of a target component in the permeate fluid from the controlled module, wherein the control device controls the secondary pressure regulating device to increase the pressure in the secondary flow path when the flow rate of the fluid to be processed detected by the primary flow rate detection device is less than or equal to a specified flow rate, or when the concentration of a target component in the permeate fluid detected by the secondary concentration detection device is less than or equal to a specified concentration.

5. A membrane separation apparatus according to any one of claims 1 to 3, comprising an upstream separation membrane module different from the controlled module, having the separation membrane, the primary side channel of the upstream separation membrane module, and the primary side channel of the controlled module being connected in series downstream of the primary side channel of the fluid to be treated.

6. The membrane separation apparatus according to claim 5, further comprising: a discharge channel for guiding the permeate fluid in the secondary channel of the upstream separation membrane module to the outside of the system; and a connecting channel for connecting the secondary channel of the upstream separation membrane module and the secondary channel of the controlled module.

7. The membrane separation apparatus according to any one of claims 1 to 3, wherein the controlled module is connected to the secondary flow path by a supply flow path for introducing fluid from outside the system.

Images