Design tool for membrane separation system

Abstract

To provide a design tool allowing for easily designing a membrane separation system using an osmotically assisted reverse osmosis (OARO) method.SOLUTION: A design tool is for designing a membrane separation system. The membrane separation system is provided with at least one semipermeable membrane module, and obtains concentrated liquid, where target components are concentrated, by using an osmotically assisted reverse osmosis method to perform membrane separation of solvent from object solution containing an object component. The design tool performs a design information output step for outputting design information for optimizing the membrane separation system by performing an information input step for inputting composition information of at least the target solution, a supply amount of the target solution, and target density of the concentrated liquid.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a design tool for membrane separation systems. [Background technology]

[0002] A membrane separation method (osmotically assisted reverse osmosis (OARO) method) is being considered, in which a high-pressure target solution is passed through the first chamber of a semipermeable membrane module having a semipermeable membrane and a first and second chamber separated by the semipermeable membrane, and a low-pressure auxiliary solution (target solution, etc.) is passed through the second chamber, causing the solvent (water, etc.) contained in the target solution in the first chamber to migrate through the semipermeable membrane to the auxiliary solution in the second chamber, thereby discharging a concentrated target solution (concentrated solution) from the first chamber and a diluted auxiliary solution (diluted solution) from the second chamber. The OARO method makes it possible to reduce the energy required for membrane separation (concentration) processing using reverse osmosis (RO) and to obtain a more highly concentrated concentrate.

[0003] For example, Patent Document 1 (International Publication No. 2018 / 084246), Patent Document 2 (Japanese Patent Laid-Open No. 2019-188330), and Patent Document 3 (Japanese Patent Laid-Open No. 2018-515340) disclose the use of a multistage membrane separation system consisting of multiple semipermeable membrane modules connected in series in an osmotically assisted reverse osmosis (OARO) process. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2018 / 084246 [Patent Document 2] Japanese Patent Application Publication No. 2019-188330 [Patent Document 3] Special Publication No. 2018-515340 Summary of the Invention [Problem to be solved by the invention]

[0005] Designing a membrane separation system using this type of osmotic-assisted reverse osmosis (OARO) process requires complex calculations that take into account the material balance of each part of the membrane separation system, and no design tool that could easily perform this was known.

[0006] Therefore, an object of the present invention is to provide a design tool that can easily design a membrane separation system using the osmotic pressure assisted reverse osmosis (OARO) method. [Means for solving the problem]

[0007] [1] A design tool for designing a membrane separation system, comprising: The membrane separation system is a system including at least one semipermeable membrane module, and performs membrane separation of a solvent from a target solution containing a target component using an osmotic pressure-assisted reverse osmosis method to obtain a concentrated solution in which the target component is concentrated; A design tool that performs an information input step of inputting at least composition information of the target solution, the supply amount of the target solution, and the target concentration of the concentrated solution, and thereby performs a design information output step of outputting design information for optimizing the membrane separation system.

[0008] [2] The design tool according to [1], wherein the design information includes an optimal number of the semipermeable membrane modules.

[0009] [3] The design tool according to [1] or [2], which performs a calculation step of calculating a material balance in the membrane separation system based on the information input in the information input step.

[0010] [4] The design tool according to [3], wherein an optimal design judgment step is carried out to determine the design information based on the material balance calculated in the calculation step.

[0011] [5] The design tool described in [4], wherein the optimal design determination step is performed by a trained model generated by machine learning.

[0012] [6] The design tool according to any one of [3] to [5], wherein in the calculation step, secondary information including at least one of the osmotic pressure, density, and viscosity of the target solution is calculated based on the information input in the information input step, and the material balance is calculated based on the secondary information.

[0013] [7] The design tool according to any one of [1] to [6], which outputs a result of predicting scale in the membrane separation system. [Effects of the Invention]

[0014] According to the present invention, it is possible to provide a design tool that can easily design a membrane separation system using the osmotically assisted reverse osmosis (OARO) method. [Brief explanation of the drawings]

[0015] [Figure 1] FIG. 2 is a flowchart illustrating an example of information processing by a design tool according to an embodiment. [Figure 2] 1 is a schematic diagram illustrating an example of a membrane separation system according to an embodiment. [Figure 3] FIG. 3 is a schematic diagram showing an example of an interface of a design tool used to design the membrane separation system shown in FIG. 2. [Figure 4] FIG. 2 is a schematic diagram showing another example of a membrane separation system according to an embodiment. [Figure 5] FIG. 5 is a schematic diagram showing an example of an interface of a design tool used to design the membrane separation system shown in FIG. 4. [Figure 6] FIG. 1 is a block diagram illustrating a configuration of a computer according to an embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0016] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the drawings, the same reference numerals denote the same or corresponding parts.

[0017] <Design tools> The design tool of this embodiment is a tool (a system equipped with a computer, a program, etc.) used to design a membrane separation system.

[0018] (Membrane separation system) The membrane separation system is a system that uses osmotic pressure-assisted reverse osmosis to separate a solvent from a target solution containing a target component, thereby obtaining a concentrated solution in which the target component is concentrated. The membrane separation system uses at least an osmotic pressure-assisted reverse osmosis (OARO) process, but may also use other membrane separation methods (e.g., reverse osmosis (RO) process, forward osmosis (FO) process, ultrafiltration) other than the OARO process.

[0019] An example of a membrane separation system according to this embodiment is shown in Fig. 2. Another example of a membrane separation system according to this embodiment is shown in Fig. 4. The membrane separation system comprises at least one semipermeable membrane module 1 . The semipermeable membrane module 1 has a semipermeable membrane 10 and a first chamber 11 and a second chamber 12 separated by the semipermeable membrane 10 .

[0020] A target solution is passed through the first chamber 11, and an auxiliary solution having an osmotic pressure is passed through the second chamber 12. The target solution has a higher pressure (hydrostatic pressure) than the auxiliary solution. That is, in each semipermeable membrane module 1, the liquid in the first chamber 11 (target solution) has a higher pressure than the liquid in the second chamber 12 (auxiliary solution). As a result, in each semipermeable membrane module, the solvent (water, etc.) contained in the target solution in the first chamber 11 migrates through the semipermeable membrane 10 to the auxiliary solution in the second chamber 12, concentrating the target solution to obtain a concentrated solution. The concentrated solution is discharged from the first chamber, and the diluted solution is discharged from the second chamber.

[0021] The target solution is pressurized by a pressurizing device or the like. Examples of the pressurizing device include high-pressure pumps 1a and 2a that can pressurize the target solution while feeding it into the first chamber 11. The pressurizing device may be a device other than a pump, and may be, for example, a device that pressurizes the liquid in the first chamber 11 from outside the semipermeable membrane module 1.

[0022] In each semipermeable membrane module, the flow direction of the liquid on both sides of the semipermeable membrane (between the first and second chambers) may be any direction, and may be opposite directions (counterflow system) or parallel directions (parallel flow system).

[0023] The membrane separation system of this embodiment may be a multi-stage membrane separation system (concentration system, etc.) equipped with a plurality of semipermeable membrane modules 1. In this case, a concentration flow path is provided in which the first chambers of a plurality of semipermeable membrane modules are connected. The concentration flow path is composed of the first chambers and a flow path connecting them. In at least some of the plurality of semipermeable membrane modules, the first chambers are preferably connected in series. In some of the plurality of semipermeable membrane modules, the first chambers may be connected in parallel. In addition, a dilution flow path is provided in which the second chambers of a plurality of semipermeable membrane modules are connected. The dilution flow path is composed of the second chambers and a flow path connecting them. In at least some of the plurality of semipermeable membrane modules, the second chambers are preferably connected in series. In some of the plurality of semipermeable membrane modules, the second chambers may be connected in parallel. The target solution flows through the concentration flow path, and the auxiliary solution having an osmotic pressure flows through the dilution flow path. The directions in which the target solution and the auxiliary solution flow are not particularly limited.

[0024] As shown in FIGS. 2 and 4, the membrane separation system of this embodiment may use reverse osmosis (RO), which is a membrane separation method other than the OARO method. 2 and 4 includes a reverse osmosis module 2 used in the RO process in addition to a semipermeable membrane module 1 used in the OARO process. The reverse osmosis module 2 includes a semipermeable membrane 20 and a first chamber 21 and a second chamber 22 separated by the semipermeable membrane 20. When high-pressure liquid is flowed into the first chamber 21, the solvent (water, etc.) contained in the liquid migrates into the second chamber 22 through the semipermeable membrane 20, and the concentrated liquid is discharged from the first chamber 21.

[0025] In the membrane separation system, the target solution may be concentrated by the RO method (reverse osmosis module 2) and then further concentrated by the OARO method (semipermeable membrane module 1) as shown in Figure 2. Alternatively, the target solution may be directly concentrated by the OARO method (semipermeable membrane module 1). As shown in Figure 4, the target solution may be concentrated by the OARO method (semipermeable membrane module 1), a portion of the concentrated liquid discharged from the first chamber 11 of the semipermeable membrane module 1 may be diluted in the second chamber 12, and the diluted liquid may be mixed into the target solution that has been concentrated by the RO method (reverse osmosis module 2).

[0026] (Design tool information processing) FIG. 1 is a flow diagram showing the flow of information processing of an example of a design tool according to this embodiment. The design tool of this embodiment performs an information input step (S10) in which at least composition information of the target solution, the supply amount of the target solution, and the target concentration of the concentrated solution are input, and then performs a design information output step (S40) in which design information for optimizing the membrane separation system is output (by a computer, etc.). That is, the design tool of this embodiment comprises information input means for carrying out the above-mentioned information input step (S10), and design information output means for carrying out the above-mentioned design information output step (S40).

[0027] In the information input step (S10), in addition to the above, other information such as information relating to the semipermeable membrane module may also be input.

[0028] Furthermore, the design tool of this embodiment performs a calculation step (S20) of calculating the material balance in the membrane separation system (using a computer or the like) based on the information input in the information input step, for example. That is, the design tool of this embodiment may include a calculation means for performing the above calculation step (S20).

[0029] Here, the material balance means the amount of material transfer, such as the concentration and flow rate of the liquid, at each location in the membrane separation system ((I) to (VIII) in Figures 2 and 4). The material balance can be calculated by a computer or the like based on the information input in the information input step using various known calculation methods for membrane separation systems.

[0030] In the calculation step (S20), for example, secondary information including at least one of the osmotic pressure, density, and viscosity of the target solution is calculated based on the information input in the information input step (S10), and a material balance may be calculated based on the secondary information.

[0031] The optimum design determination step (S30) for determining design information can be performed, for example, based on the material balance calculated in the calculation step.

[0032] The design information is not particularly limited as long as it is information for optimizing the membrane separation system, and an example of the design information is the optimal number of semipermeable membrane modules. Other design information includes, for example, the type and size of the semipermeable membrane module, the required pressure of the first chamber 11 in the semipermeable membrane module 1, the flow rate of the auxiliary solution to the second chamber 12, and the like.

[0033] The optimal design determination step (S30) may be performed by a trained model (artificial intelligence: AI) generated by machine learning.

[0034] The design tool of this embodiment may further output scale prediction results in the membrane separation system (prediction results such as the components and amount of scale generated at various points in the membrane separation system) (based on the amount of acid added, the target concentration of the concentrated liquid, etc.). In this case, it is possible to design a membrane separation module to minimize the amount of scale generated, or to design a membrane separation module that takes into account maintenance depending on the amount of scale generated.It is also possible to verify the feed water composition conditions that prevent scale generation due to concentration.

[0035] (Design tool configuration) A specific configuration of the design tool for realizing the above functions will be described below.

[0036] The functions of the design tool of this embodiment can be realized by, for example, a computer. The functions of the design tool may be realized by one computer, or may be realized by other computers connected over a network or the cloud.

[0037] Referring to FIG. 6, computer 100 includes, as main components, a CPU (Central Processing Unit) 110, a memory 120, an operation unit 140, and an interface 160.

[0038] The CPU 110 controls each part of the computer 100 by executing a program stored in the memory 120. For example, the CPU 110 executes the program stored in the memory 120 and performs the various information processes described above by referring to various data.

[0039] The memory 120 is realized by RAM (Random Access Memory), ROM (Read-Only Memory), etc., and may be included in the computer 100, may be detachable from various interfaces of the computer 100, or may be a recording medium of another device accessible from the computer 100. The memory 120 stores programs executed by the CPU 110, data generated by the execution of programs by the CPU 110, input data, and other databases used for information processing according to this embodiment.

[0040] The operation unit 140 receives commands from the user of the design tool and inputs the commands to the CPU 110 . The input of various information in the above-mentioned information input step (S10), instructions to execute information processing, etc. can be performed by the operation unit 140 (see information input sections 41a to 41c, etc. on the interface screens shown in FIGS. 3 and 5).

[0041] Note that interface 160 may be a communication interface that transmits data from CPU 110 to other devices (computers, communication terminals, etc.) via the Internet, a carrier network, a router, etc. Conversely, the communication interface receives data from other devices via the Internet, a carrier network, a router, etc., and passes it to CPU 110.

[0042] The CPU 110 receives data such as various pieces of information input in the information input step (S10) via the operation unit 140, the interface 160, and the like. The CPU 110 executes information processing such as a calculation step (S20) on the received data. The information obtained in the calculation step (S20) may be displayed on a display screen or the like of a computer that constitutes the interface 160 (see output display sections 42a to 42e of the interface screen shown in FIGS. 3 and 5).

[0043] Furthermore, the CPU 110 executes an optimum design determination step (S30) based on the information obtained in the calculation step (S20).

[0044] The optimal design determination step (S30) is executed by the CPU 110 based on, for example, a trained model stored in the memory 120.

[0045] The trained model is generated based on a large amount of data, for example, by machine learning (deep learning, etc.). The generated trained model can be used as software or an application on a computer to implement the optimal design decision step.

[0046] As a method for creating training data used in machine learning, for example, a person determines, for example, the number, type, size, etc. of semipermeable membrane modules (BC modules) based on information input into information input sections 41a to 41c of the interface screen shown in FIGS. 3 and 5, and on the basis of a manual for designing membrane separation systems and the experience of an expert, while referring to the mass balance, etc., shown on the output display section 42a. In this way, machine learning is carried out using a large amount of training data that links input data (information on the composition of the target solution, the supply amount of the target solution, information on the semipermeable membrane module with the target concentration of the concentrated solution, etc.) with output data (optimal number, type, size, operating conditions, etc. of semipermeable membrane modules).

[0047] The design information (for example, the optimum number of semipermeable membrane modules) determined in the optimum design determination step (S30) is presented to the user from the CPU 110 via the interface 160 or the like (see the output display unit 42b).

[0048] (target solution and auxiliary solution) The target solution and auxiliary solution are not particularly limited as long as the target component is dissolved in a solvent. Examples of solvents include water, and the target component can be any component that dissolves in the solvent. For example, salt water (brine, seawater, brackish water, etc.), industrial wastewater (aqueous solution containing inorganic salts, aqueous solution containing water-soluble organic solvents, etc.), etc. can be used. The above-mentioned membrane separation system is particularly suitable for further concentrating the target solution when it is a highly concentrated (high osmotic pressure) solution such as brine.

[0049] The target solution or the like may be subjected to pretreatment to remove fine particles, microorganisms, scale components, etc. contained in the solution. As the pretreatment, various known pretreatments used in seawater desalination technology or the like can be carried out, and examples thereof include filtration using an NF membrane, UF membrane, MF membrane, etc., addition of sodium hypochlorite, addition of a coagulant, activated carbon adsorption treatment, ion exchange resin treatment, etc. Such pretreatment is preferably carried out before the target solution and auxiliary solution are supplied to the semipermeable membrane module.

[0050] Theoretically, membrane separation by the OARO method is possible if the osmotic pressure difference (absolute value) between the target solution (liquid to be concentrated) flowing through the first chamber 11 (high-pressure side) and the auxiliary solution (liquid to be diluted) flowing through the second chamber 12 (low-pressure side) is smaller than the pressure of the target solution. In this case, it is preferable that the difference in osmotic pressure between the target solution and the auxiliary solution be 30% or less of the pressure of the target solution.

[0051] The auxiliary solution is not particularly limited as long as it is a liquid having osmotic pressure, but a part of the target solution (concentrated solution) concentrated in the first chamber 11 of the semipermeable membrane module 1 may be supplied as the auxiliary solution to the second chamber 12 of the semipermeable membrane module 1. In this case, it is preferable to provide a mechanism (for example, a flow rate control valve 31) for adjusting the ratio of the concentrated solution supplied as the auxiliary solution to the second chamber 12 of the semipermeable membrane module 1 relative to the total amount of the concentrated solution. Furthermore, it is preferable that a mechanism for reducing the pressure of the liquid is provided in the flow path for supplying a part of the concentrated liquid as an auxiliary solution to the second chamber 12 of the semipermeable membrane module 1. Examples of such a mechanism include a device such as the first chamber pressure regulating valve 33 that keeps the pressure high on the upstream side and reduces the pressure on the downstream side, and an energy recovery device that has a mechanism for converting energy recovered from the pressurized supply liquid into auxiliary energy for driving a pump or the like. The valve 32 is normally fully opened during operation in order to supply a part of the concentrated solution to the second chamber 12 of the semipermeable membrane module 1 as an auxiliary solution.

[0052] In the concentration process (membrane separation process) by the OARO method using the semipermeable membrane module 1, osmotic pressure acting in the opposite direction to the direction in which the solvent moves from the first chamber 11 to the second chamber 12 is unlikely to occur, so concentration can proceed at a lower pressure (pump pressure) than in the reverse osmosis (RO) method. Therefore, in the membrane separation system of this embodiment, which mainly performs concentration by the OARO method, the power consumption of pumps, etc. can be reduced, and the energy efficiency of concentration can be improved.

[0053] Furthermore, in RO concentration, the osmotic pressure of the concentrated target solution on one side of the semipermeable membrane is generated in the opposite direction to the pump pressure. Therefore, when the osmotic pressure of the concentrated target solution reaches the pump pressure, the pump pressure and the osmotic pressure of the target solution acting in the opposite direction are balanced, preventing any further water from passing through the semipermeable membrane and preventing concentration from proceeding. In contrast, in membrane separation processes (concentration methods) using the OARO method, the difference in concentration (osmotic pressure difference) between the liquids supplied to the first and second compartments in each semipermeable membrane module is small, and the osmotic pressure that inhibits concentration processes like in the RO method is unlikely to occur. Therefore, a membrane separation system (concentration system) using the OARO method can increase the final concentration of the target solution more than a membrane separation system using only the RO method. In principle, it is thought that the target solution can be concentrated to its saturated concentration.

[0054] (semi-permeable membrane) Examples of the semipermeable membrane used in this embodiment include semipermeable membranes called reverse osmosis membranes (RO membranes), forward osmosis membranes (FO membranes), nanofiltration membranes (NF membranes), and ultrafiltration membranes (UF membranes). The semipermeable membrane is preferably a reverse osmosis membrane, a forward osmosis membrane, or a nanofiltration membrane. When a reverse osmosis membrane, a forward osmosis membrane, or a nanofiltration membrane is used as the semipermeable membrane, the pressure of the liquid (target solution) in the first chamber is preferably 0.5 to 10.0 MPa.

[0055] Typically, RO and FO membranes have pore sizes of approximately 2 nm or less, and UF membranes have pore sizes of approximately 2 to 100 nm. NF membranes have a relatively low rejection rate for ions and salts compared to other RO membranes, and typically have pore sizes of approximately 1 to 2 nm. When an RO membrane, FO membrane, or NF membrane is used as the semipermeable membrane, the salt rejection rate of the RO membrane, FO membrane, or NF membrane is preferably 90% or higher.

[0056] The material constituting the semipermeable membrane is not particularly limited, but examples thereof include cellulose-based resins, polysulfone-based resins, polyamide-based resins, etc. The semipermeable membrane is preferably made of a material containing at least one of a cellulose-based resin and a polysulfone-based resin.

[0057] The cellulose-based resin is preferably a cellulose acetate-based resin. Cellulose acetate-based resins are resistant to chlorine, a disinfectant, and have the characteristic of being able to inhibit the growth of microorganisms. The cellulose acetate-based resin is preferably cellulose acetate, and from the viewpoint of durability, more preferably cellulose triacetate.

[0058] The polysulfone-based resin is preferably a polyethersulfone-based resin. The polyethersulfone-based resin is preferably a sulfonated polyethersulfone.

[0059] In the drawings, the semipermeable membranes of the semipermeable membrane modules are depicted as flat membranes for simplification, but the shape of the semipermeable membranes is not particularly limited. The semipermeable membranes may be flat membranes such as spiral membranes (spiral-type semipermeable membranes) or hollow fiber membranes (hollow fiber-type semipermeable membranes), but hollow fiber membranes are preferred. Hollow fiber membranes are advantageous in that they have a smaller membrane thickness than flat membranes and can increase the membrane area per module, thereby increasing the permeation efficiency.

[0060] When the semipermeable membrane is a hollow fiber membrane, it is preferable that in each semipermeable membrane module, the first chamber is outside the hollow fiber membrane and the second chamber is inside the hollow fiber membrane (hollow portion). This is because even if the solution flowing inside the hollow fiber membrane is pressurized, the pressure loss may become large and it may be difficult to pressurize sufficiently, and also because, although hollow fiber membranes generally easily maintain their structure against external pressure, the hollow fiber membrane may be damaged if the internal pressure becomes too high.

[0061] A specific example of a hollow fiber membrane is a membrane with a single layer structure composed entirely of a cellulose-based resin. However, the single layer structure referred to here does not necessarily mean a membrane with a uniform layer throughout; for example, it may be a membrane that is non-uniform in the thickness direction. Specifically, the membrane may have a dense layer on the outer surface, which serves as a separation active layer that essentially determines the pore size of the hollow fiber membrane, and the inner surface side may have a lower density than the dense layer. Since the dense layer essentially serves as a separation active layer that determines the pore size of the hollow fiber membrane, when the solution outside the hollow fiber membrane is pressurized, having a dense layer on the outer surface of the hollow fiber membrane allows for more accurate control of the movement of molecules from the outside to the inside of the hollow fiber membrane.

[0062] Another specific example of a hollow fiber membrane is a two-layer membrane having a dense layer of polyphenylene resin (e.g., sulfonated polyethersulfone) on the outer surface of a support layer (e.g., a layer made of polyphenylene oxide). Another example is a two-layer membrane having a dense layer of polyamide resin on the outer surface of a support layer (e.g., a layer made of polysulfone or polyethersulfone). [Explanation of symbols]

[0063] 1 semipermeable membrane module, 10 semipermeable membrane, 11 first chamber, 12 second chamber, 2 reverse osmosis module, 20 semipermeable membrane, 21 first chamber, 22 second chamber, 31 flow rate control valve, 32 valve, 33 first chamber pressure control valve, 100 computer, 110 CPU, 120 memory, 140 operation unit, 160 communication interface.

Claims

1. 1. A design tool for designing a membrane separation system, comprising: The membrane separation system is a system including at least one semipermeable membrane module, and performs membrane separation of a solvent from a target solution containing a target component using an osmotic pressure-assisted reverse osmosis method to obtain a concentrated solution in which the target component is concentrated; A design tool that performs an information input step of inputting at least composition information of the target solution, the supply amount of the target solution, and the target concentration of the concentrated solution, and thereby performs a design information output step of outputting design information for optimizing the membrane separation system.

2. The design tool according to claim 1 , wherein the design information includes an optimal number of the semipermeable membrane modules.

3. The design tool according to claim 1 , further comprising a calculation step for calculating a material balance in the membrane separation system based on the information input in the information input step.

4. 4. The design tool according to claim 3, further comprising: an optimal design determination step for determining the design information based on the material balance calculated in the calculation step.

5. The design tool according to claim 4 , wherein the optimal design determination step is performed by a trained model generated by machine learning.

6. 4. The design tool according to claim 3, wherein in the calculation step, secondary information including at least one of an osmotic pressure, a density, and a viscosity of the target solution is calculated based on the information input in the information input step, and the material balance is calculated based on the secondary information.

7. The design tool according to claim 1 , which outputs a scale prediction result for the membrane separation system.

Images