Method and apparatus for evaluating performance of ion exchange membrane in electrodialysis process

Abstract

The present invention provides an apparatus and a method for evaluating the performance of an ion exchange membrane in an electrodialysis process, the method comprising the steps of: supplying deionized water corresponding to a basic input flow rate to an acid chamber and a base chamber; measuring the concentration of a solution in each chamber according to the basic input flow rate; estimating a characteristic value of an ion exchange membrane on the basis of the measured concentration of the solution; determining an input flow rate of the deionized water corresponding to a target concentration of the solution by using the estimated characteristic value; supplying the deionized water to each chamber at the determined input flow rate for a predetermined operation time; and evaluating the performance of the ion exchange membrane on the basis of a performance index determined after the predetermined operation time has elapsed.

Description

Method and apparatus for evaluating the performance of an ion exchange membrane in an electrodialysis process

[0001] This description claims priority to Korean Patent Application No. 10-2024-0191919, and the contents of the said patent application specification are all incorporated into this specification.

[0002] This description relates to a method and apparatus for evaluating the performance of an ion exchange membrane in an electrodialysis process.

[0003] Bipolar Electrodialysis (BPED) is an electro-separation process used to separate or concentrate specific ions from a solution using ion exchange materials. BPED is gaining prominence as a particularly important water separation and regeneration technology.

[0004] BPED operation data may include various data collected during the operation of the technology. BPED operation data may include, for example, current and voltage data, substance concentration data, temperature and pressure data, and time data.

[0005] In order to improve BPED operations based on experience and increase the productivity of lithium (Li), there is a need for a model that predicts the concentration of lithium produced based on operation data. The prediction results can be used for the control or optimization of the production process.

[0006] One embodiment provides a device for evaluating the performance of an ion exchange membrane in an electrodialysis process.

[0007] Another embodiment provides a method for evaluating the performance of an ion exchange membrane in an electrodialysis process.

[0008] According to one embodiment, a device for evaluating the performance of an ion exchange membrane in an electrodialysis process is provided. The device comprises an ion exchange section in which sulfate ions and lithium ions of an aqueous lithium sulfate solution are exchanged through an ion exchange membrane under an electric field, a flow rate supply section for controlling the flow rate of the aqueous lithium sulfate solution and deionized water introduced into the ion exchange section, and a solution storage section for storing a solution produced by the exchange of sulfate ions and lithium ions. The ion exchange section comprises a first chamber into which the aqueous lithium sulfate solution is introduced, a second chamber adjacent to the first chamber with an anion dialysis membrane among the ion exchange membranes, and a third chamber adjacent to the first chamber with a cation dialysis membrane among the ion exchange membranes. The flow rate supply section determines the flow rate of deionized water so that the concentration of the aqueous sulfuric acid solution in the second chamber and the concentration of the aqueous lithium hydroxide solution in the third chamber are maintained at a predetermined target concentration.

[0009] In the above device, the flow supply unit can supply deionized water to the second chamber at a basic input flow rate, estimate the characteristic value of the anion dialysis membrane based on the measured concentration of the aqueous sulfuric acid solution, and determine the input flow rate of deionized water corresponding to the target concentration of the aqueous sulfuric acid solution using the estimated characteristic value.

[0010] In the above device, the flow supply unit supplies deionized water to the third chamber at a basic input flow rate, estimates the characteristic value of the cation dialysis membrane based on the measured concentration of the lithium hydroxide aqueous solution, and uses the estimated characteristic value to determine the input flow rate of deionized water corresponding to the target concentration of the lithium hydroxide aqueous solution.

[0011] According to another embodiment, a method for evaluating the performance of an ion exchange membrane in an electrodialysis process is provided. The method comprises the steps of: supplying deionized water corresponding to a first basic input flow rate to a second chamber adjacent to a first chamber through which an aqueous lithium sulfate solution is introduced, with an anion dialysis membrane among the ion exchange membranes in between; measuring the concentration of the aqueous sulfuric acid solution in the second chamber according to the first basic input flow rate; estimating a first characteristic value of the anion dialysis membrane based on the measured concentration of the aqueous sulfuric acid solution; determining a first input flow rate of deionized water corresponding to a target concentration of the aqueous sulfuric acid solution using the first characteristic value; supplying the deionized water to the second chamber at the first input flow rate for a predetermined operating time; and evaluating the performance of the anion dialysis membrane based on a performance indicator determined after the predetermined operating time has elapsed.

[0012] In the above method, the first characteristic value may represent the ratio of the amount of water that moves to the second chamber along with the sulfate ions when the sulfate ions move to the second chamber through the anion dialysis membrane.

[0013] In the above method, the step of determining a first input flow rate of deionized water corresponding to a target concentration of an aqueous sulfuric acid solution using a first characteristic value may include the step of determining a first input flow rate based on the amount of sulfate ion movement, the measured concentration of the aqueous sulfuric acid solution, and the amount of water movement according to the first characteristic value.

[0014] In the above method, the amount of sulfate ion migration can be determined based on the effective membrane area of ​​the anion dialysis membrane, the current density of the current that generated the electric field of the electrodialysis process, and the current efficiency of the electrodialysis process.

[0015] The above method may further include the steps of: supplying deionized water corresponding to a second basic input flow rate to a third chamber adjacent to a first chamber with a cation dialysis membrane in between; measuring the concentration of a lithium hydroxide aqueous solution in the third chamber according to the second basic input flow rate; estimating a second characteristic value of the cation dialysis membrane based on the measured concentration of the lithium hydroxide aqueous solution; determining a second input flow rate of deionized water corresponding to a target concentration of the lithium hydroxide aqueous solution using the second characteristic value; supplying deionized water to the third chamber at the second input flow rate for a predetermined operating time; and evaluating the performance of the cation dialysis membrane based on a performance indicator determined after the predetermined operating time has elapsed.

[0016] In the above method, the second characteristic value may represent the ratio of the amount of water that moves to the third chamber along with the lithium ions when the lithium ions move through the cation dialysis membrane.

[0017] In the above method, the step of determining a second input flow rate of deionized water corresponding to a target concentration of a lithium hydroxide aqueous solution using a second characteristic value may include the step of determining a second input flow rate based on the amount of lithium ion movement, the measured concentration of the lithium hydroxide aqueous solution, and the amount of water movement according to the second characteristic value.

[0018] In the above method, the amount of lithium ion movement can be determined based on the effective membrane area of ​​the cation dialysis membrane, the current density of the current that generated the electric field of the electrodialysis process, and the current efficiency of the electrodialysis process.

[0019] A performance evaluation device (100) according to one embodiment can determine the input flow rate of deionized water according to the characteristic value of the ion exchange membrane and supply deionized water at the determined input flow rate, thereby enabling the performance of the ion exchange membrane to be accurately measured during a long-term electrodialysis process.

[0020] FIG. 1 shows a performance evaluation device for evaluating the performance of an ion exchange membrane in an electrodialysis process according to one embodiment.

[0021] FIG. 2 shows a schematic diagram of a performance evaluation device according to one embodiment.

[0022] FIG. 3 shows a method for evaluating the performance of an ion exchange membrane according to one embodiment.

[0023] FIG. 4 shows a performance evaluation device according to another embodiment.

[0024] The embodiments of this description are described below with reference to the attached drawings so that those skilled in the art can easily implement them. However, this description may be implemented in various different forms and is not limited to the embodiments described herein. Furthermore, in order to clearly explain this description in the drawings, parts unrelated to the explanation have been omitted, and similar parts throughout the specification are denoted by similar reference numerals.

[0025] In this description, each of the phrases such as “A or B”, “at least one of A and B”, “at least one of A or B”, “A, B or C”, “at least one of A, B and C”, and “at least one of A, B, or C” may include any one of the items listed together in the corresponding phrase, or all possible combinations thereof.

[0026] In this description, when a part is described as "including" a certain component, it means that, unless specifically stated otherwise, it does not exclude other components but may include additional components.

[0027] Expressions written in the singular in this description may be interpreted as singular or plural unless explicit expressions such as "one" or "single" are used.

[0028] In this description, "and / or" includes each of the mentioned components and all combinations of one or more.

[0029] In this description, terms including ordinal numbers, such as first, second, etc., may be used to describe various components, but said components are not limited by said terms. Such terms are used solely for the purpose of distinguishing one component from another. For example, without departing from the scope of the present disclosure, the first component may be named the second component, and similarly, the second component may be named the first component.

[0030] In the flowchart described herein with reference to the drawings, the order of operations may be changed, multiple operations may be merged or some operations may be divided, and certain operations may not be performed.

[0031] FIG. 1 shows a block diagram of a performance evaluation device for evaluating the performance of an ion exchange membrane in an electrodialysis process according to one embodiment, and FIG. 2 shows a schematic diagram of a performance evaluation device according to one embodiment.

[0032] In FIGS. 1 and 2, a performance evaluation device (100) for an ion exchange membrane according to one embodiment can evaluate the performance of the ion exchange membrane in an electrodialysis process through a bipolar electrodialysis (BPED) process. Since the performance and stability of the BPED process can be determined by a combination of a bipolar membrane (BPM), a cation exchange membrane (CEM), and an anion exchange membrane (AEM), the ion exchange membrane needs to be tested and evaluated before being introduced into the BPED process in large quantities. In one embodiment, the performance evaluation device (100) can evaluate the long-term performance of the ion exchange membrane by conducting the BPED process for a long period at a very low flow rate compared to a commercial facility or a pilot plant (PP) facility.

[0033] In one embodiment, the output of the electrodialysis process (BPED) can be determined by the discharge flow rates of the aqueous sulfuric acid solution and the aqueous lithium hydroxide solution. Additionally, the output of the electrodialysis process can be determined by the control of the input flow rate of deionized water (H2O), the input flow rate of lithium sulfate, the current and voltage of the rectifier, and the pH, conductivity, circulation flow rate, and circulation pressure within each room. The control and management elements that form the basis for calculating performance indicators such as the input flow rate of the solution, the current and voltage of the rectifier, pH, conductivity, circulation flow rate, and circulation pressure can be detected through internal sensors installed in each room. The control and management elements may correspond to variables that determine the concentrations of the lithium hydroxide and sulfuric acid produced.

[0034] Referring to FIG. 1, the performance evaluation device (100) may include an ion exchange unit (110), a flow rate supply unit (120), a solution circulation unit (130), and a solution storage unit (140).

[0035] In one embodiment, within the ion exchange section (110) of the performance evaluation device (100), sulfate ions and lithium ions of an aqueous lithium sulfate (Li2SO4) solution (LS solution) can be exchanged between each chamber within the ion exchange section (110) through an ion exchange membrane under an electric field.

[0036] Referring to FIGS. 1 and 2, the ion exchange unit (110) includes an acid chamber, a salt chamber, and a base chamber between two electrodes that supply an electric field. A positive electrode membrane is disposed between the acid chamber and the positive electrode and between the base chamber and the negative electrode. A cation exchange membrane may be disposed between the salt chamber and the base chamber, and an anion exchange membrane may be disposed between the acid chamber and the salt chamber.

[0037] In one embodiment, the cation exchange membrane includes an anion group inside, so that cations (e.g., lithium ions (Li)) + )) can be allowed to pass through the cation exchange membrane and move from the salt room to the base room. The anion exchange membrane contains cation groups internally, allowing anions (e.g., sulfate ions (SO4)) to pass through. 2- This allows it to pass through the anion exchange membrane and move from the salt room to the acid room.

[0038] In one embodiment, the anode membrane consists of a cation membrane and an anion membrane overlapping with a water splitting catalyst in between. The anode membrane splits water within an electric field to produce hydrogen ions (H₂). + ) and hydroxide ions (OH - ) can be generated. Accordingly, the performance evaluation device (100) uses an electrodialysis membrane (cation dialysis membrane, anion dialysis membrane, and anode membrane) in an electric field to perform water splitting (generation of H+, OH-) / ion separation (Li + , SO4 2- It can perform ion separation simultaneously.

[0039] In a performance evaluation device (100) according to one embodiment, the LS solution is Li + and SO4 2-Ions are transferred to the base room and the acid room, respectively, and in the base room and the acid room, an aqueous solution of lithium hydroxide (LiOH) (LH solution) and an aqueous solution of sulfuric acid (H2SO4) (HS solution) can be generated, respectively. For example, in the performance evaluation device (100), deionized water (DI Water) can be converted into an LH solution and an HS solution by coming into counter-flow contact with the LS solution.

[0040] In one embodiment, the flow supply unit (120) can control the flow rate of the LS solution and deionized water introduced into the ion exchange unit (110) via the solution circulation unit (130).

[0041] In one embodiment, the solution circulation unit (130) may include a base tank for storing an aqueous sulfuric acid solution generated from sulfate ions that have passed through an anion exchange membrane, an acid tank for storing an LH solution generated from lithium ions that have passed through a cation exchange membrane, and a salt tank for storing desalted water derived from an LS solution. Deionized water supplied from the flow supply unit (120) may be delivered to the base room and acid room within the ion exchange unit (110) via the base tank and the acid tank.

[0042] Referring to FIG. 2, the salt chamber, acid chamber, and base chamber of the ion exchange unit (110) can be connected to the salt tank, acid tank, and base tank of the solution circulation unit (130), respectively. An LS solution is supplied to the salt chamber from the salt tank, and deionized water can be produced after the reaction. Deionized water is supplied to the acid chamber, and an HS solution can be produced after the reaction. Deionized water is supplied to the base chamber, and an LH solution can be produced after the reaction.

[0043] The solution storage unit (140) is connected to a salt tank so that deionized water of the LS solution can be stored in the solution storage unit (140). Additionally, the solution storage unit (140) is connected to an acid tank so that the HS solution produced in the acid room can be stored in the solution storage unit (140). Additionally, the solution storage unit (140) is connected to a base tank so that the LH solution produced in the base room can be stored in the solution storage unit (140).

[0044] In one embodiment, if the conductivity of the base chamber is measured to be a small value, the flow supply unit (120) can increase the concentration of the base solution by reducing the flow rate of deionized water supplied to the base chamber. If the pH of the salt chamber increases as the flow rate of deionized water supplied to the base chamber decreases, the flow supply unit (120) can, in response, reduce the flow rate of deionized water supplied to the acid chamber to increase the conductivity of the acid chamber and maintain the pH of the salt chamber at a predetermined level.

[0045] In one embodiment, if the conductivity of the base chamber is measured to be a high value, the flow supply unit (120) can increase the flow rate of deionized water supplied to the base chamber to lower the concentration of the base solution. If the pH of the salt chamber decreases as the flow rate of deionized water supplied to the base chamber increases, the flow supply unit (120) can increase the flow rate of deionized water supplied to the acid chamber in response to lower the conductivity of the acid chamber and maintain the pH of the salt chamber at a predetermined level.

[0046] In one embodiment, if the pH of the salt chamber exceeds a predetermined reference pH, the flow supply unit (120) can reduce the flow rate of deionized water supplied to the acid chamber to increase the concentration in the acid chamber and lower the pH of the salt chamber. To achieve pH equilibrium, the flow supply unit (120) can increase the flow rate of deionized water supplied to the base chamber to lower the concentration in the base chamber, thereby increasing the pH of the salt chamber. In one embodiment, the pH of the salt chamber needs to be managed to be smaller than a predetermined reference pH (e.g., pH=2.5).

[0047] Meanwhile, when the pH of the salt chamber drops to an excessively acidic state, the flow supply unit (120) can increase the flow rate of deionized water supplied to the acid chamber to lower the concentration in the acid chamber and raise the pH of the salt chamber. When the pH of the salt chamber is measured to be above a predetermined reference pH, the flow supply unit (120) can increase the flow rate of deionized water supplied to the base chamber to lower the concentration in the base chamber and lower the pH of the salt chamber so that the pH is maintained under equilibrium conditions.

[0048] In one embodiment, when the conductivity of the acid chamber is measured to be low (i.e., when the concentration of the produced acid solution is lower than the target value), the flow supply unit (120) can increase the concentration of the acid solution by reducing the flow rate of deionized water supplied to the acid chamber. At this time, if the pH of the salt chamber is lowered as the flow rate of deionized water supplied to the acid chamber is reduced, the flow supply unit (120) can reduce the flow rate of deionized water supplied to the base chamber in response to increase the conductivity of the base chamber and maintain the pH of the salt chamber within a predetermined range of reference pH.

[0049] In one embodiment, when the conductivity of the acid chamber is measured to be high (i.e., when the concentration of the produced acid solution is lower than the target value), the flow supply unit (120) can increase the flow rate of deionized water supplied to the acid chamber to lower the concentration of the acid solution. At this time, if the pH of the salt chamber increases as the flow rate of deionized water supplied to the acid chamber increases, the flow supply unit (120) can increase the flow rate of deionized water supplied to the base chamber in response to lower the conductivity of the base chamber and maintain the pH of the salt chamber within a predetermined range of reference pH. Since the concentration of the produced base solution must not fall below the target concentration, there may be a limit to increasing the flow rate of deionized water supplied to the base chamber.

[0050] In one embodiment, the flow supply unit (120) can maintain the concentration of the HS solution at a target concentration by introducing an appropriate flow rate of deionized water into the acid chamber. In one embodiment, the concentration of the HS solution produced through the electrodialysis process can be determined as shown in Equation 1 below.

[0051]

[0052] In mathematical formula 1 is the amount of sulfate ions transferred to the acid chamber through the anion dialysis membrane, and is the amount of water transferred to the acid chamber through the anion dialysis membrane, and ... is the flow rate of deionized water introduced into the acid chamber. Therefore, the input flow rate of deionized water to be supplied to the acid chamber by the flow supply unit (120) It can be calculated as shown in mathematical formula 2 below.

[0053]

[0054] In one embodiment, the amount of sulfate ion movement through the anion dialysis membrane It can be calculated as shown in mathematical formula 3 below.

[0055]

[0056] For example, the effective membrane area of ​​the anion dialysis membrane is 550 cm² 2 And, the current density of the current that generated the electric field is 80 mA / cm² 2 And, when the current efficiency of the performance evaluation device (100) is 58% and the Faraday constant representing the charge of 1 mole of electrons is 96,485 C / mol, is 0.76g-SO4 2- It can be calculated as / min. In the calculation of Equation 2, since the sulfate ion is a divalent ion, the current efficiency is halved (*0.5), and the molecular weight of the sulfate ion, 96.1, is multiplied by the result.

[0057] In addition, the amount of water transferred to the acid chamber through the anion dialysis membrane (A) can be calculated as shown in mathematical formula 4 below.

[0058]

[0059] In mathematical formula 4, ε is the ratio of the amount of water that moves into the acid chamber along with sulfate ions when sulfate ions move through the anion dialysis membrane, and is a characteristic value of the anion dialysis membrane. In one embodiment, It may vary depending on the characteristics of the anion dialysis membrane (membrane selectivity, membrane hydration, membrane structure, membrane thickness, etc.). Or It can be affected by the size and charge of ions moving through the anion dialysis membrane, and can vary depending on the difference in the number of ions on both sides of the anion dialysis membrane. Or The current efficiency of the performance evaluation device (100) or the current density related to the electric field may vary.

[0060] In one embodiment, the flow supply unit (120) can maintain the concentration of the LH solution at a target concentration by introducing an appropriate flow rate of deionized water into the base chamber. In one embodiment, the concentration of the LH solution produced through the electrodialysis process can be determined as shown in Equation 5 below.

[0061]

[0062] In mathematical formula 5 is the amount of lithium ions transferred to the base chamber through the cation dialysis membrane, and is the amount of water transferred to the base chamber through the cation dialysis membrane, and is the flow rate of deionized water introduced into the base chamber. Therefore, the flow rate of deionized water to be supplied to the base chamber by the flow rate supply unit (120) It can be calculated as shown in mathematical formula 6 below.

[0063]

[0064] In one embodiment, the amount of lithium ion movement through the cation dialysis membrane It can be calculated as shown in mathematical formula 7 below.

[0065]

[0066] For example, the effective membrane area of ​​the cation dialysis membrane is 550 cm² 2 And, the current density of the current that generated the electric field is 80 mA / cm² 2 And, when the current efficiency of the performance evaluation device (100) is 58% and the Faraday constant representing the charge of 1 mole of electrons is 96,485 C / mol, is 0.110g-Li + It can be calculated as / min. In the calculation of Equation 7, the molecular weight of the lithium ion, 6.94, is multiplied to the result.

[0067] In addition, the amount of water transferred to the base chamber through the cation dialysis membrane (C) can be calculated as shown in mathematical formula 8 below.

[0068]

[0069] In mathematical formula 4, ε is the ratio of the amount of water that moves into the base chamber along with the lithium ions when the lithium ions move through the cation dialysis membrane, and is a characteristic value of the cation dialysis membrane. In one embodiment, It may vary depending on the characteristics of the cation dialysis membrane (membrane selectivity, membrane hydration, membrane structure, membrane thickness, etc.). Or It can be affected by the size and charge of the ions moving through the cation dialysis membrane, and can vary depending on the difference in the number of ions on both sides of the membrane. Or The current efficiency of the performance evaluation device (100) or the current density related to the electric field may vary.

[0070] FIG. 3 shows a method for evaluating the performance of an ion exchange membrane according to one embodiment.

[0071] A performance evaluation device (100) according to one embodiment can determine the input flow rate of deionized water to maintain the target concentration of the acid room and the base room, supply the deionized water corresponding to the determined input flow rate to the acid room and the base room for a predetermined operating time to carry out the BPED process, and then evaluate the performance of the ion exchange membrane. The flow rate of deionized water supplied to the acid room and the base room is very small compared to commercial facilities or PP facilities, and therefore, the performance evaluation device (100) according to one embodiment can accurately evaluate the performance of the ion exchange membrane by operating the electrodialysis device for a long time without damaging the ion exchange membrane.

[0072] Referring to FIG. 3, the flow supply unit (120) of the performance evaluation device (100) can start an electrodialysis process by supplying deionized water to the ion exchange unit (110) as a basic input flow rate (S110). The flow supply unit (120) can predetermine the basic input flow rate of the deionized water supplied to the acid room and the base room. For example, the flow supply unit (120) can determine the basic input flow rate as a minimum flow rate (e.g., 0.5 g per minute) for the progress of the electrodialysis process. Alternatively, the flow supply unit (120) can determine the input flow rate optimized through several electrodialysis processes as the basic input flow rate.

[0073] When the electrodialysis process is carried out for a predetermined time at a basic input flow rate, the concentration of the solution in the acid chamber and the base chamber is measured by a sensor of the ion exchange unit (110), and the flow supply unit (120) can determine the characteristic value of the anion dialysis membrane and the characteristic value of the cation dialysis membrane using the measured concentration of the solution in the acid chamber and the base chamber based on mathematical formulas 2, 3, and 4 (S120, S130).

[0074] In one embodiment, the flow supply unit (120) uses the measured concentration of the HS solution in the acid chamber to determine the characteristic value of the anion dialysis membrane It can be estimated.

[0075] For example, the flow supply unit (120) supplies deionized water to the acid chamber at a basic input flow rate of 9g per minute ( =9g / min) When the measured concentration of the HS solution is 24.2003gS / Liter, the flow supply unit (120) is based on mathematical formulas 1 to 4. It can be estimated as shown in mathematical formula 9 below.

[0076]

[0077] In mathematical equation 9, sulfur (S) and sulfate ions (SO4 2- The ratio of molecular weights between ) (molecular weight 황 :Molecular weight황산이온 The concentration of the HS solution, 24.2003 g / Liter, was converted to 0.0725 g / g using the equation (=32.1:96.1). The amount of sulfate ion transfer in Equation 9 0.76 g / min is when the effective membrane area of ​​the anion dialysis membrane is 550 cm² 2 And, the current density of the current that generated the electric field is 80 mA / cm² 2 This is a value determined when the current efficiency of the performance evaluation device (100) is 58%. Since the sulfate ion is a divalent ion, the current efficiency can be calculated as 29%.

[0078] In addition, the flow supply unit (120) uses the measured concentration of the LH solution in the base chamber to [describe] the characteristic value of the cation dialysis membrane It can be estimated.

[0079] For example, the flow supply unit (120) supplies deionized water to the base room at a basic input flow rate of 5g per minute ( =5g / min) When the measured concentration of the LH solution is 20.3g-Li / Liter, the flow supply unit (120) is based on mathematical formulas 5 to 8. It can be estimated as shown in mathematical formula 10 below.

[0080]

[0081] In Equation 10, the concentration of the LH solution, 20.3 g / Liter, was converted to 0.0203 g / g using the fact that 1 g = 1 / 1000 Liter when the density of the LH solution is assumed to be 1. The amount of lithium ion movement in Equation 10 0.110 g / min is when the effective membrane area of ​​the cation dialysis membrane is 550 cm² 2 And, the current density of the current that generated the electric field is 80 mA / cm² 2 This is a value determined when the current efficiency of the performance evaluation device (100) is 58%.

[0082] Referring to FIG. 3, the flow supply unit (120) can determine the input flow rate of deionized water corresponding to the target concentrations of the acid chamber and base chamber using the estimated characteristic value of the ion exchange membrane (S140, S150).

[0083] In one embodiment, the flow supply unit (120) is estimated Input flow rate of deionized water to maintain the target concentration of the HS solution using can decide.

[0084] For example, assuming the target concentration of the HS solution is 35 g-S / Liter and the solution density is 1 (1 liter = 1000 g), the target concentration of sulfate ions in the HS solution is 0.1048 g / g (molecular weight 황 :Molecular weight 황산이온 It can be determined as =32.1:96.1).

[0085] The flow supply unit (120) has a target concentration of sulfate ions in the HS solution of 0.1048 and is estimated from Equation 9 Input flow rate of deionized water to be supplied to the acid chamber to maintain the target concentration using It can be determined as shown in mathematical formula 11 below.

[0086]

[0087] Referring to mathematical formula 11, when the flow supply unit (120) supplies 5.77 g of deionized water per minute to the acid chamber, the target concentration of the HS solution, 35 g-S / Liter, can be maintained.

[0088] Also, the flow supply unit (120) is estimated Input flow rate of deionized water to maintain the target concentration of the LH solution using can decide.

[0089] For example, when the target concentration of the LH solution is 25 g-Li / Liter and the solution density is assumed to be 1 (1 liter = 1000 g), the target concentration of the LH solution can be determined to be 0.025 g / g.

[0090] The flow supply unit (120) has a target concentration of 0.025 of the LH solution and is estimated from Equation 10 Input flow rate of deionized water to be supplied to the base room to maintain the target concentration using It can be determined as shown in mathematical formula 12 below.

[0091]

[0092] Referring to mathematical formula 12, when the flow supply unit (120) supplies 3.98 g of deionized water per minute to the base chamber, the target concentration of the LH solution can be maintained at 25 g-S / Liter.

[0093] Referring to FIG. 3, the flow supply unit (120) supplies deionized water to the acid room and the base room, respectively, at the input flow rate determined as above (S160), and the performance of the ion exchange membrane can be evaluated based on an indicator representing the characteristics of the ion exchange membrane measured by the sensor of the ion exchange unit (110) (S170).

[0094] Table 1 below shows the performance indicators of the performance evaluation device (100) and the PP facility. In Table 1, Device 1 is a performance evaluation device (100) that produces high-concentration sulfuric acid, and Device 2 is a performance evaluation device (100) that produces low-concentration sulfuric acid. Referring to Table 1, the performance evaluation device (100) can increase the concentration of the produced HS solution by supplying a smaller input flow rate of deionized water to the acid chamber. At this time, the flow rate supply unit (120) [uses] the characteristic value of the anion dialysis membrane based on the above mathematical formulas 1 to 4 Estimate, and the estimated The input flow rate of deionized water supplied to the acid room can be determined using [this method].

[0095] Classification Standard Value PP Facility Device 1 (High Concentration Sulfuric Acid) Device 2 (Low Concentration Sulfuric Acid) Base Room Lithium Concentration (g / Liter) ~ 2019.36 19.79 19.46 LH Solution Quality (S / Li) < 0.1 0.0 3 0.0 7 0.0 2HS Solution Quality (Li / S) < 0.0 6 5 0.0 5 0.0 5 0.0 4HS Solution Concentration (%)≥ 8.0 9.8 3 9.8 2 6.9 3HS Solution Sulfur Concentration (g / Liter) 3 4.4 5 6 2 3.7 Supply Flow Rate Ratio 3.0 3.1 4.9 Operating Time (hour) ~ 2 ~ 196 ~ 210 LS Solution Injection Flow Rate (ml / min) 20.0 20.0 Deionized Water Injection Flow Rate (base) (ml / min) 1.5 1.8 Deionized Water Injection Flow Rate (acid) (ml / min) 4.6 8.8

[0096] The ion exchange membranes used in the performance evaluation of Table 1 were AD100, CH100, and BHD20, and the Li concentration (S / Li) was measured as the quality of the LH solution, and the indicator items representing membrane characteristics (e.g., LH solution quality, HS solution quality) were measured similarly for high-concentration sulfuric acid and low-concentration sulfuric acid, respectively. For low-concentration sulfuric acid (6.93%), the performance evaluation device (100) was operated for 8 hours continuously, at which time the pH of the salt room was measured as 2.22 and the lithium concentration (Base-Li) of the base room was measured as 19.46 g. For high-concentration sulfuric acid (9.82%), the performance evaluation device (100) was operated for 5 hours continuously, at which time the pH of the salt room was measured as 1.34 and the lithium concentration of the base room was measured as 19.79 g / L. In this way, the performance evaluation device (100) according to one embodiment can determine the input flow rate of deionized water according to the characteristic value of the ion exchange membrane and supply deionized water at the determined input flow rate, thereby enabling the performance of the ion exchange membrane to be accurately measured during a long-term electrodialysis process.

[0097] FIG. 4 shows a performance evaluation device according to another embodiment.

[0098] A performance evaluation device according to another embodiment may be implemented as a computer system, for example, a computer-readable medium. Referring to FIG. 4, the computer system (400) may include at least one of a processor (410) communicating via a bus (470), a memory (430), an input interface device (450), an output interface device (460), and a storage device (440). The computer system (400) may also include a communication device (420) coupled to a network.

[0099] At least one processor (410) may be a central processing unit (CPU) or a semiconductor device that executes instructions stored in memory (430) or a storage device (440). The processor (410) may implement the function, process, or method proposed in the embodiment. The operation of the computer system (400) according to the embodiment may be implemented by the processor (410). At least one processor (410) may include at least one of a GPU, a CPU, and an NPU. When the operation of the computer system (400) is implemented by at least one processor (410), each task may be divided among at least one processor (410) according to the load. For example, when one processor is a CPU, the other processor may be any one of a GPU, an NPU, an FPGA, or a DSP.

[0100] The memory (430) and storage device (440) may include various forms of volatile or non-volatile storage media. For example, the memory may include ROM (read only memory) and RAM (random access memory). The memory (430) may be connected to the processor (410) and may store various information for driving the processor (410) or at least one program executed by the processor (410). Alternatively, the memory (430) may store instructions that cause the processor (410) to perform a process included in the function, process, or method proposed in the embodiment.

[0101] In the embodiments of the present description, the memory may be located inside or outside the processor, and the memory may be connected to the processor through various known means. The memory is a volatile or non-volatile storage medium of various forms, and, for example, the memory may include read-only memory (ROM) or random access memory (RAM).

[0102] Accordingly, the embodiment may be implemented as a method implemented on a computer or as a non-transient computer-readable medium storing computer-executable instructions. In one embodiment, when executed by a processor, the computer-readable instructions may perform a method according to at least one aspect of the present description.

[0103] The communication device (420) can transmit or receive wired or wireless signals.

[0104] Meanwhile, the embodiments are not implemented solely through the devices and / or methods described so far, but may also be implemented through a program that realizes a function corresponding to the configuration of the embodiments or a recording medium on which such a program is recorded. Such implementation can be easily achieved by a person skilled in the art to which the present invention pertains, based on the description of the embodiments described above. Specifically, the method according to the embodiments may be implemented in the form of program instructions that can be executed through various computer means and may be recorded on a computer-readable medium. The computer-readable medium may include program instructions, data files, data structures, etc., either individually or in combination. The program instructions recorded on the computer-readable medium may be specially designed and configured for the embodiments, or they may be known and available to a person skilled in the art of computer software. The computer-readable recording medium may include a hardware device configured to store and execute program instructions. For example, computer-readable recording media may be magnetic media such as hard disks, floppy disks, and magnetic tapes; optical recording media such as CD-ROMs and DVDs; magneto-optical media such as floptical disks; ROM; RAM; flash memory; etc. Program instructions may include machine code, such as that generated by a compiler, as well as high-level language code that can be executed by a computer through an interpreter, etc.

[0105] Although the embodiments have been described in detail above, the scope of the rights is not limited thereto, and various modifications and improvements by those skilled in the art using the basic concepts defined in the following claims are also included within the scope of the rights.

Claims

1. As a device for evaluating the performance of an ion exchange membrane in an electrodialysis process, An ion exchange section in which sulfate ions and lithium ions of an aqueous lithium sulfate solution are exchanged through the ion exchange membrane under an electric field, A flow supply unit for controlling the input flow rate of the lithium sulfate aqueous solution and deionized water introduced into the above ion exchange unit, and A solution storage unit that stores a solution produced by the exchange of the above sulfate ions and the above lithium ions. Includes, The above ion exchange unit comprises a first chamber into which the above lithium sulfate aqueous solution is introduced, a second chamber adjacent to the first chamber with an anion dialysis membrane among the ion exchange membranes, and a third chamber adjacent to the first chamber with a cation dialysis membrane among the ion exchange membranes. The above flow supply unit determines the input flow rate of the deionized water so that the concentration of the aqueous sulfuric acid solution in the second chamber and the concentration of the aqueous lithium hydroxide solution in the third chamber are maintained at a predetermined target concentration.

2. In Paragraph 1, The above flow supply unit is, After supplying the deionized water to the second chamber at a basic input flow rate, the characteristic value of the anion dialysis membrane is estimated based on the measured concentration of the aqueous sulfuric acid solution, and A device for determining the input flow rate of the deionized water corresponding to the target concentration of the aqueous sulfuric acid solution using the above estimated characteristic value.

3. In Paragraph 1, The above flow supply unit is, After supplying the deionized water to the third chamber at a basic input flow rate, the characteristic value of the cation dialysis membrane is estimated based on the measured concentration of the lithium hydroxide aqueous solution, and An apparatus for determining the input flow rate of the deionized water corresponding to the target concentration of the lithium hydroxide aqueous solution using the above estimated characteristic value.

4. As a method for evaluating the performance of an ion exchange membrane in an electrodialysis process, A step of supplying deionized water corresponding to a first basic input flow rate to a second chamber adjacent to a first chamber into which a lithium sulfate aqueous solution is introduced, with an anion dialysis membrane among the ion exchange membranes in between. A step of measuring the concentration of the aqueous sulfuric acid solution in the second chamber according to the first basic input flow rate, A step of estimating a first characteristic value of the anion dialysis membrane based on the measured concentration of the above-mentioned aqueous sulfuric acid solution, A step of determining the first input flow rate of the deionized water corresponding to the target concentration of the aqueous sulfuric acid solution using the first characteristic value above, The step of supplying the deionized water to the second chamber at the first input flow rate for a predetermined operating time, and A step of evaluating the performance of the anion dialysis membrane based on performance indicators determined after the above-mentioned predetermined operating time has elapsed. A method including 5. In Paragraph 4, A method in which the first characteristic value represents the ratio of the amount of water that moves to the second chamber together with the sulfate ions when the sulfate ions move to the second chamber through the anion dialysis membrane.

6. In Paragraph 5, The step of determining the first input flow rate of the deionized water corresponding to the target concentration of the aqueous sulfuric acid solution using the first characteristic value above is: A step of determining the first input flow rate based on the amount of sulfate ion movement, the measured concentration of the aqueous sulfuric acid solution, and the amount of water movement according to the first characteristic value. A method including 7. In Paragraph 6, A method in which the amount of sulfate ion transported is determined based on the effective membrane area of ​​the anion dialysis membrane, the current density of the current that generated the electric field of the electrodialysis process, and the current efficiency of the electrodialysis process.

8. In Paragraph 4, A step of supplying deionized water corresponding to a second basic input flow rate to a third chamber adjacent to the first chamber with a cation dialysis membrane among the ion exchange membranes in between. A step of measuring the concentration of the lithium hydroxide aqueous solution in the third chamber according to the second basic input flow rate, A step of estimating a second characteristic value of the cation dialysis membrane based on the measured concentration of the above lithium hydroxide aqueous solution, A step of determining a second input flow rate of the deionized water corresponding to the target concentration of the lithium hydroxide aqueous solution using the second characteristic value above, The step of supplying the deionized water to the third chamber at the second input flow rate for a predetermined operating time, and A step of evaluating the performance of the cation dialysis membrane based on performance indicators determined after the above-mentioned predetermined operating time has elapsed. A method that includes more.

9. In Paragraph 8, A method in which the second characteristic value represents the ratio of the amount of water that moves to the third chamber along with the lithium ions when the lithium ions move through the cation dialysis membrane.

10. In Paragraph 9, The step of determining the second input flow rate of the deionized water corresponding to the target concentration of the lithium hydroxide aqueous solution using the second characteristic value above is: A step of determining the second input flow rate based on the amount of lithium ion movement, the measured concentration of the lithium hydroxide aqueous solution, and the amount of water movement according to the second characteristic value. A method including 11. In Paragraph 10, A method in which the amount of lithium ion movement is determined based on the effective membrane area of ​​the cation dialysis membrane, the current density of the current that generated the electric field of the electrodialysis process, and the current efficiency of the electrodialysis process.

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