Liquid separation system

Abstract

A liquid separation system (1) includes a separation module (2) comprising a separation section (21) and a processing liquid flow path (41) for the flow of a liquid to be processed (d). The separation section (21) comprises a ceramic substrate having a plurality of fine pores. The separation section (21) separates the liquid to be separated (Lq) contained in the liquid to be processed (d) by allowing the liquid to be separated (Lq) to pass through in a vapor (v) state. The liquid separation system (1) separates the liquid to be separated (Lq) from the liquid to be processed (d) by controlling a specific relationship by a control section (3). The specific relationship is the relationship between the heat supplied to the separation section (21) and the heat removed from the separation section (21) due to the evaporation of the liquid to be separated (Lq) contained in the liquid to be processed (d).

Description

[Technical Field]

[0001] This invention relates to a liquid separation system. [Previous Technology]

[0002] For example, as shown in Patent Document 1, a membrane distillation apparatus is known in which the liquid to be treated is passed through the inside of a hollow fiber membrane serving as the membrane for membrane distillation to perform membrane distillation. The membrane distillation apparatus described in Patent Document 1 performs membrane distillation with high efficiency and long-term stability by setting the Reynolds number of the liquid to be treated flowing through the inside of the membrane for membrane distillation to 1100 or more, and setting the linear velocity of the liquid to be treated flowing through the inside of the membrane for membrane distillation to 3.5 m / s or less. [Prior Art Documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2023-092086 [Summary of the Invention]

[0004] However, the membrane distillation apparatus described in Patent Document 1 does not take into account the relationship between the heat supplied to the membrane for membrane distillation and the heat removed from the membrane for membrane distillation due to the evaporation of the liquid to be separated contained in the liquid being processed. Therefore, even if the Reynolds number and linear velocity of the liquid being processed are controlled as described above, there is a concern that the liquid to be separated cannot be effectively separated from the liquid being processed. That is, in order to perform membrane distillation with high efficiency, if the area of ​​the membrane for membrane distillation is increased, the temperature of the membrane for membrane distillation tends to drop due to the evaporation of the liquid to be separated from the liquid being processed. Therefore, depending on the heat supplied to the membrane for membrane distillation, there is a concern that the separation efficiency will decrease due to the decrease in the temperature of the membrane for membrane distillation. Therefore, from the viewpoint of effectively separating the liquid to be separated from the liquid being processed, there is room for further improvement.

[0005] In view of related issues, the present invention provides a liquid separation system that can improve separation efficiency.

[0006] One aspect of the present invention is a liquid separation system comprising a separation module for separating a liquid from a liquid being processed. The separation module comprises: a ceramic substrate having a plurality of fine pores, a separation section for separating the liquid from the liquid being processed by allowing the liquid to be separated, which is contained in the liquid being processed, to pass through in a vapor state, and a processing liquid flow path for the liquid being processed to flow through. The separation section has a permeable surface facing the processing liquid flow path, through which the vapor passes. A control section for controlling a specific relationship between the heat supplied to the separation section and the heat removed from the separation section due to the evaporation of the liquid to be separated contained in the liquid being processed, wherein the control section controls the specific relationship to separate the liquid from the liquid being processed.

[0007] The liquid separation system described above controls the specific relationship described above to separate the liquid to be separated from the liquid being processed. Therefore, by increasing the area of ​​the permeable surface of the separation section, even if the heat lost from the separation section due to the evaporation of the liquid to be separated increases, the temperature drop of the separation section can be suppressed. That is, the liquid to be separated can be efficiently separated from the liquid being processed, and therefore, even with an increased permeable surface area, the temperature drop of the separation section can be suppressed. As a result, the separation efficiency of the separation section can be prevented from decreasing, and the separation efficiency can be improved.

[0008] As described above, based on the above-described state, a liquid separation system that can improve separation efficiency can be provided.

Implementation Method

[0010] (Embodiment 1) An embodiment of the liquid separation system will be described with reference to FIGS. 1 to 6. The liquid separation system 1 of this embodiment, as shown in FIGS. 1 to 3, includes a separation module 2 for separating a liquid Lq from a liquid being processed (d). The separation module 2 includes a separation section 21 and a processing liquid flow path 41 for the liquid being processed (d) to flow through. As shown in FIG. 6, the separation section 21 includes a ceramic substrate 22 having a plurality of fine pores 20. As indicated by arrow FL1 in FIGS. 1, 4, and 6, the separation section 21 separates the liquid Lq contained in the liquid being processed (d) by allowing the liquid Lq to pass through in the form of vapor v. Furthermore, the separation section 21 has a permeable surface 211, which faces the processing liquid flow path 41 and allows vapor v to pass through.

[0011] The liquid separation system 1, as shown in FIG1, has a control unit 3 that controls a specific relationship. The specific relationship is the relationship between the heat supplied to the separation unit 21 and the heat removed from the separation unit 21 due to the evaporation of the liquid Lq contained in the liquid being processed d. The liquid separation system 1 separates the liquid Lq from the liquid being processed d by controlling the specific relationship through the control unit 3.

[0012] The liquid separation system 1 is a purification device applicable to, for example, the purification treatment of factory wastewater or waste liquid. Specifically, the liquid separation system 1 can be used to remove various substances, including minerals, from factory wastewater or waste liquid. The wastewater or wastewater being treated may be, for example, wastewater or waste liquid discharged from electroplating or coating processes. The substances contained in the wastewater or waste liquid may be, for example, oil, heavy metals, fluorides, phosphoric acid compounds, Na (i.e., sodium), Mg (i.e., magnesium), CaCO₃ (i.e., calcium carbonate), etc.

[0013] The liquid separation system 1 of this embodiment, as shown in FIG1, can, for example, separate water as liquid Lq from the drain water, which is the liquid being treated, through membrane distillation. The separation module 2 can, for example, separate the liquid Lq from the liquid being treated in the state of water vapor, which is vapor v. The liquid separation system 1 of this embodiment has a supply flow path 52 for supplying the liquid being treated d from the plant F to the separation module 2, and a recovery flow path 54 for recovering the liquid Lq separated from the liquid being treated d by the separation module 2.

[0014] The treated liquid d discharged from factory F is supplied to the drain tank 57 and then pumped to the separation module 2 by pump 51. The treated liquid d is then heated to the desired temperature by the heating unit 58 and sent to the separation module 2. The treated liquid d processed by the separation module 2 is discharged from the separation module 2 as concentrated treated liquid d (hereinafter referred to as concentrated liquid d) to the discharge flow path 52a. In this embodiment, the concentrated liquid d discharged from the separation module 2 is returned to the drain tank 57 via the discharge flow path 52a, mixed with other treated liquids d, and then processed again by the separation module 2. Furthermore, the separated liquid Lq separated by the separation module 2 is sent to the purified liquid tank 56 via the recovery flow path 54. Specifically, the recovery flow path 54 is provided with a cooling unit 55 for cooling the vapor v and turning it into a condensate. The vapor v from the separation module 2 is condensed into a condensate by the cooling section 55 and is contained in the purification liquid tank 56 as the purified liquid Lq. The separated liquid Lq in the purification liquid tank 56 can be reused, for example, in the factory F. Furthermore, the heating section 58 for heating the treated liquid d can be, for example, installed in the supply flow path 52, and can be a heat exchanger, an electric heater, a heat pump, etc. The cooling section 55 can be, for example, a chiller for circulating low-temperature water, an air-cooled heat exchanger, a water-cooled heat exchanger, a cooling tower, etc.

[0015] Next, the separation module 2 will be described in detail. In this embodiment, the separation module 2, as shown in Figures 2 and 3, has a honeycomb structure. The separation module 2 includes a cylindrical outer skin portion 101. The outer skin portion 101 of the separation module 2 is divided by a plurality of cells 102 formed along the axial direction x of the separation module 2. The internal space of each cell 102 is a flow path for the flow of the liquid being treated d or the vapor v. That is, the plurality of cells 102 have a liquid flow path 41 for the flow of the liquid being treated d and a vapor flow path 42 for the flow of the vapor v.

[0016] The separation module 2 has a cylindrical shape. The direction along the flow path 41 of the liquid being processed d is defined as the flow direction FD. Furthermore, as shown in FIG2, in the separation module 2, the length of the flow direction FD of the separable portion 25 capable of separating the liquid to be separated Lq from the liquid being processed d is defined as the length Lm. In this case, the length L is 0.05~1.00m. The outer diameter OD of the separable portion 25 viewed from the flow direction FD is 80~265mm. In this embodiment, the axial direction x can also be the flow direction FD.

[0017] In this embodiment, the separable portion 25 is the part of the separation module 2 that includes the separation portion 21, the processing liquid flow path 41, and the vapor flow path 42. Furthermore, in the flow direction FD, the separable portion 25 is the portion of the separation module 2 located inside the plug portion 104 (described later), and when viewed from the flow direction FD, the separable portion 25 is the portion of the separation module 2 located inside the outer skin portion 101. Therefore, the length L of the separable portion 25 is the length of the separation module 2 excluding the plug portion 104. Also, when viewed from the flow direction FD, the outer diameter OD of the separable portion 25 is the same length as the inner diameter of the outer skin portion 101.

[0018] Furthermore, the processing liquid flow path 41 of the separation module 2 is connected to the supply flow path 52 (see Figure 1), and the vapor flow path 42 is connected to the recovery flow path 54 (see Figure 1). As shown in Figures 2 and 3, the supply flow path 52 is connected to the processing liquid flow path 41 on one end face of the separation module 2 in the flow direction FD. The processed liquid d supplied from the supply flow path 52 flows into the processing liquid flow path 41 from one side of the separation module 2 in the flow direction FD, as shown by arrow FL3 in Figures 2 and 3, and flows through the processing liquid flow path 41 towards the other side of the separation module 2 in the flow direction FD. Then, the concentrated liquid d processed by the separation module 2 is discharged from the other end face of the separation module 2 in the flow direction FD to the discharge flow path 52a.

[0019] Furthermore, the separation module 2, as shown in Figures 1 to 6, has a nest wall 103 that divides the nest chambers 102. That is, the nest chambers 102 that serve as the processing liquid flow path 41 and the nest chambers 102 that serve as the vapor flow path 42 are divided by the nest wall 103. In this embodiment, a portion of the nest wall 103 serves as the separation section 21, and the processing liquid flow path 41 and the vapor flow path 42 are arranged adjacent to each other across the separation section 21.

[0020] The cells 102 of the separation module 2, for example, as shown in Figures 2 and 5, can be quadrangular cells with a quadrangular shape when viewed from the axial direction x of the separation module 2. When viewed from the axial direction x, a plurality of quadrangular cells 102 are arranged parallel to each other in two mutually perpendicular directions (for example, the horizontal direction y and the vertical direction z as shown in Figure 2). Specifically, in the first direction (here, the horizontal direction y) parallel to one side of the quadrangular cells when viewed from the axial direction x, a plurality of cells 102 serving as the processing liquid flow path 41 are arranged adjacent to each other, and a plurality of cells 102 serving as the vapor flow path 42 are also arranged adjacent to each other. Furthermore, in the second direction (here, the vertical direction z) perpendicular to the first direction, the cells 102 serving as the processing liquid flow path 41 and the cells 102 serving as the vapor flow path 42 are alternately arranged. However, the terms "horizontal" or "vertical" used here are for convenience and do not necessarily mean that the separation module 2 is used with the horizontal direction y being horizontal in Figure 2.

[0021] In this embodiment, the cell 102 serving as the processing liquid flow path 41 is an open cell with openings at both ends, and the cell 102 serving as the vapor flow path 42 is a plugged cell with both ends closed by the plug portion 104. That is, only the cell 102 serving as the vapor flow path 42 has both ends plugged by the plug portion 104. The plug portion 104 used to plug the cell 102 can be formed, for example, from a ceramic material, glass, resin, etc.

[0022] In this embodiment, the cell 102, which serves as the vapor flow path 42, is connected to the other cell 102 through a slit 105, which is a communication opening formed in the cell wall 103 between adjacent cells 102, as shown in FIG2. Specifically, the slit 105 is configured to penetrate the cell wall 103 so that vapor v can flow between adjacent vapor flow paths 42 in each column. The slit 105 of the vapor flow path 42 serves as a flow path for discharging vapor v to the outside of the separation module 2.

[0023] As shown in FIG3, in the outer skin portion 101, which serves as the outer peripheral side surface of the separation module 2, an opening portion 106 with a shape approximately the same as the slit 105 is provided at the position corresponding to each column of slits 105. The vapor v from the vapor flow path 42, as shown by arrow FL2 in FIG3, is discharged through the slits 105 in each column and exited through the opening portion 106, and is recycled back to the recycling flow path 54.

[0024] Furthermore, in this embodiment, the liquid separation system 1 separates the liquid to be separated, Lq, from the liquid to be processed, d, using vacuum membrane distillation. That is, the liquid separation system 1 uses a pressure reducing device 53 (see Figure 1) installed in the recovery flow path 54 to reduce the pressure of the vapor flow path 42 connected to the recovery flow path 54, thereby using the vapor pressure difference or pressure difference between the liquid to be processed flow path 41 and the vapor flow path 42 as the driving force for membrane distillation. In this embodiment, the pressure reducing device 53 is a vacuum pump. The suction pressure generated by the vacuum pump 53 can be set, for example, to be higher than 0 kPa and lower than 100 kPa. Preferably, the suction pressure generated by the vacuum pump 53 is set to 90 kPa or lower. Also, in this embodiment, the liquid to be processed, d, is heated by the heating unit 58, creating a temperature difference between the liquid to be processed flow path 41 and the vapor flow path 42; therefore, membrane distillation is performed using the vapor pressure difference generated by the separation unit 21 as the driving force.

[0025] The heating unit 58 heats the liquid to be processed d to a desired temperature. The liquid to be processed d heated by the heating unit 58 is introduced into the liquid processing flow path 41. The heating unit 58 may, for example, heat the liquid to be processed d to a temperature below its boiling point. For example, if the liquid to be processed d is a mixture or aqueous solution containing water, the heating unit 58 may heat the liquid to be processed supplied to the separation module 2 to 60°C to 120°C, taking into account the increase in boiling point. In this way, a desired temperature difference required to exhibit a vapor pressure difference is provided between the liquid processing flow path 41 and the vapor flow path 42. Furthermore, preferably, the temperature of the liquid to be processed d supplied to the separation module 2 is 100°C or less, more preferably 80°C or less.

[0026] Next, the separation section 21 will be described in detail. The separation section 21, which constitutes part of the nest wall 103 of the separation module 2, is configured, as shown by arrow FL1 in Figures 1, 4, and 6, to allow vapor v to pass through from the permeable surface 211 facing the processing liquid flow path 41 toward the side facing the vapor flow path 42, thereby separating the liquid Lq from the processed liquid d. That is, the portion of the nest wall 103 used to separate the processing liquid flow path 41 and the vapor flow path 42 serves as the separation section 21. Furthermore, the separation section 21 has the same structure as the nest wall 103 used to separate adjacent processing liquid flow paths 41 and the nest wall 103 used to separate adjacent vapor flow paths 42. In other words, the separation section 21 has the same structure as the portion of the nest wall 103 other than the separation section 21.

[0027] In this embodiment, each processing fluid flow path 41, as shown in FIG5, is surrounded by two permeable surfaces 211 formed along the horizontal direction y and two nest walls 103 formed along the vertical direction z. That is, in this embodiment, the two surfaces formed along the vertical direction z in the face facing the processing fluid flow path 41 are not permeable surfaces 211.

[0028] Furthermore, as shown in FIG. 6, in the separation section 21, a plurality of fine pores 20 provided in the ceramic substrate 22 connect adjacent processing liquid flow paths 41 and vapor flow paths 42 to form a passage for vapor v. Thereby, as shown in FIGS. 1-4 and 6, the processed liquid d, during its passage through the processing liquid flow path 41, is separated as vapor v, becoming a more concentrated concentrate d. In this embodiment, the ceramic substrate 22 is made of porous ceramic. The ceramic substrate 22 may contain at least one material selected from, for example, aluminum, mullite, silicon dioxide, silicon carbide, zirconium oxide, and kaolinite.

[0029] Furthermore, in this embodiment, a cover layer 214 is formed on the surface of the ceramic substrate 22, as shown in FIG6. The cover layer 214 is formed at least on the permeable surface 211 of the ceramic substrate 22. In this embodiment, the cover layer 214 is also formed on the pore-forming surface 212 where the pores 20 are formed. The cover layer 214 may be composed of, for example, a condensate of fluoroalkyl silanes or hydrocarbon materials. Furthermore, the contact angle of the treated liquid d with respect to the surface of the cover layer 214 is greater than 90°. That is, the cover layer 214 is hydrophobic.

[0030] Next, the control performed by the control unit 3 will be explained. In this embodiment, the temperature of the liquid to be processed d supplied to the processing liquid flow path 41 is higher than the temperature of the separation unit 21. In this embodiment, the specific relationship is the relationship between the supply amount Qm3 / h of the liquid to be processed d supplied to the separation module 2 per unit time and the area Sm2 of the permeable surface 211. The control unit 3 controls the specific relationship by adjusting the supply amount Q.

[0031] The control unit 3 includes a processor and memory. In this embodiment, the control unit 3 controls the pump 51 shown in FIG. 1 to adjust the supply amount Q. Thereby, the control unit 3 adjusts the heat supplied to the separation unit 21, controlling a specific relationship. That is, by controlling the control unit 3, the more the supply amount Q to the separation module 2 is increased, the more heat is supplied from the processed liquid d to the separation unit 21; conversely, the more the supply amount Q is decreased, the less heat is supplied from the processed liquid d to the separation unit 21. Furthermore, in this embodiment, the control unit 3 adjusts the temperature of the processed liquid d by controlling the heating unit 58.

[0032] The area S of the total area of ​​the permeable surfaces 211 in the separation module 2 can be set to, for example, 2 m² or more, and the supply rate Q can be set to, for example, 2.5 to 20.0 m³ / h. Furthermore, the liquid processing volume Flux per unit time can be set to, for example, 4 to 15 kg / m² / h. Liquid processing volume Flux is the permeable flow, referring to the amount of separated liquid Lq per unit area of ​​the permeable surface 211 per unit time. In other words, liquid processing volume Flux is the amount of separated liquid Lq per unit area of ​​the permeable surface 211 per unit time, separated from the treated liquid d in the state of vapor v.

[0033] In this embodiment, the liquid separation system 1 is controlled by the control unit 3 to have a Q / S value of 0.2 to 8.8, which is the ratio of the supply amount Q to the area S of the permeable surface 211. More preferably, the liquid separation system 1 is controlled by the control unit 3 to have a Q / S value of 0.6 to 4.0, and even more preferably, to have a Q / S value of 1 to 3.

[0034] Next, the effects of this embodiment will be explained. The liquid separation system 1 described above controls a specific relationship to separate the liquid Lq to be separated from the liquid being processed d. Therefore, by increasing the area of ​​the permeable surface 211 of the separation section 21, even if the heat lost from the separation section 21 due to the evaporation of the liquid Lq to be separated increases, the temperature drop of the separation section 21 can be suppressed. That is, the liquid Lq to be separated can be efficiently separated from the liquid being processed d, so even when the area of ​​the permeable surface 211 is increased, the temperature drop of the separation section 21 can be suppressed. As a result, the separation efficiency of the separation section 21 can be prevented from decreasing, and the separation efficiency can be improved.

[0035] Specifically, in order to increase the liquid throughput (Flux), increasing the area S of the permeable surface 211 makes it easier to increase the area where the liquid to be separated (Lq) can be separated from the liquid being processed (d) in the state of vapor (v). However, a larger area S of the permeable surface 211 also makes it easier to lose more heat from the separation section 21. Specifically, the larger the area S of the permeable surface 211, the more easily the latent heat generated by the phase change during the evaporation of the liquid being processed (d) from the liquid to be separated (Lq) is lost from the separation section 21. Therefore, the temperature near the permeable surface 211 of the separation section 21 will decrease, and the vapor pressure around the permeable surface 211 will decrease, which may lead to a decrease in the liquid throughput (Flux). Therefore, the liquid separation system 1 of this embodiment controls a specific relationship. Therefore, even if the heat lost from the separation section 21 increases due to the evaporation of the liquid to be separated (Lq), by increasing the heat supplied to the separation section 21 to compensate for the lost heat, the decrease in the liquid throughput (Flux) caused by the temperature drop of the separation section 21 can be suppressed. As a result, the separation efficiency of the separation section 21 can be prevented from decreasing and the separation efficiency can be improved.

[0036] In this embodiment, the specific relationship is the relationship between the supply amount Q and the area S of the permeable surface 211. The control unit 3 controls the specific relationship by adjusting the supply amount Q. Therefore, the separation efficiency can be significantly improved. That is, even if the heat taken away from the separation unit 21 increases due to the increase in the area S of the permeable surface 211, the heat taken away can be compensated by increasing the supply amount Q, and the heat supplied from the processed liquid d to the separation unit 21 can be increased to suppress the temperature drop of the separation unit 21. As a result, the separation efficiency can be significantly improved.

[0037] In this embodiment, the liquid separation system 1 is controlled by the control unit 3 to have a Q / S value of 0.2 to 8.8. Therefore, separation efficiency, energy efficiency, and separation performance can be significantly improved. Specifically, by setting the Q / S value to 0.2 or higher, the supply amount Q to the area S is sufficiently ensured, and the heat supplied from the higher-temperature treated liquid d to the separation unit 21 is also ensured. Therefore, the temperature drop of the separation unit 21 can be suppressed, and separation efficiency can be significantly improved. However, while increasing the Q / S value increases the supply amount Q and easily suppresses the temperature drop of the separation unit 21, it also easily increases the pressure loss when the treated liquid d flows through the processing liquid flow path 41. Furthermore, if the Q / S value is set too high, there is concern that the treated liquid d may pass through the separation unit 21, and there is concern that the separation performance of the separation module 2 may decrease. Therefore, in this embodiment, the Q / S value is set to 8.8 or lower. This suppresses the pressure loss when the treated liquid d flows through the processing liquid flow path 41. As a result, both energy efficiency and separation performance can be significantly improved. Furthermore, preferably, the liquid separation system 1 is controlled by the control unit 3 to have a Q / S value of 0.6 to 4.0. In this case, separation efficiency, energy efficiency, and separation performance can be further improved. More preferably, the liquid separation system 1 is controlled by the control unit 3 to have a Q / S value of 1 to 3. In this case, as shown in Figures 7 and 9 of Experimental Example 1, Figure 11 of Experimental Example 2, and Figure 12 of Experimental Example 3, separation efficiency, energy efficiency, and separation performance can be further improved.

[0038] The separation module 2 has a cylindrical shape. The length L is 0.05~1.00m. Furthermore, the outer diameter OD of the separable section 25 when viewed from the flow direction FD is 80~265mm. Therefore, the miniaturization of the separation module 2 can be ensured while ensuring a sufficient liquid handling capacity (Flux).

[0039] The ceramic substrate 22 is composed of porous ceramic. The ceramic substrate 22 may contain at least one material selected from aluminum, mullite, silicon dioxide, silicon carbide, zirconium oxide, and conglaze. In this case, the separation module 2 can suppress deterioration even when processing acidic or alkaline solutions d. Furthermore, for example, to resolve blockages in the processing fluid flow path 41, the separation module 2 can be cleaned with acidic or alkaline cleaning agents, thus suppressing deterioration. As a result, the durability of the separation module 2 can be improved, thereby extending its lifespan.

[0040] As described above, according to this embodiment, a liquid separation system 1 capable of improving separation efficiency can be provided.

[0041] (Experimental Example 1) In this experimental example, as shown in Figures 7-10, a liquid separation system with the same basic structure as in Embodiment 1 was used. The relationship between the Q / S value and the liquid throughput (Flux) was obtained by changing the supply rate Q. The experimental conditions were as follows: the area S of the permeable surface in the separation module was set to 2.51 m², the supply rate Q was set to 0.5-30 m³ / h, the air permeability coefficient of the separation section was set to 5 × 10⁻⁷ m³ / s·m²·Pa, the suction pressure of the vacuum pump was set to 90 kPa, the inner diameter of the processing liquid flow path was set to 1 mm, the length L of the separable section was set to 0.2 m, the outer diameter OD of the separable section was set to 150 mm, the liquid to be processed was a sodium chloride aqueous solution, and the liquid to be separated was water. Figures 7 and 8 show the results when the temperature of the liquid to be processed was set to 60°C, and Figures 9 and 10 show the results when the temperature of the liquid to be processed was set to 75°C. As shown in Figures 7 and 9, when the temperature of the treated liquid is 60°C and 75°C, the liquid throughput (Flux) reaches saturation when the Q / S value is 8. That is, although the figures are omitted, the liquid throughput (Flux) is equivalent when the Q / S value is greater than 8 and when the Q / S value is 8. Furthermore, in this experimental example, the first benchmark is defined as 50% or more of the liquid throughput (Flux) at a Q / S value of 8, representing a benchmark with better separation efficiency. The second benchmark is defined as 75% or more of the liquid throughput (Flux) at a Q / S value of 8, representing a benchmark with even better separation efficiency. Therefore, the Q / S value satisfying these benchmarks is determined from the results of this experimental example. However, when the temperature of the treated liquid is 60°C, the liquid throughput (Flux) at a Q / S value of 8 is 3 kg / m² / h, and when the temperature of the treated liquid is 75°C, the liquid throughput (Flux) at a Q / S value of 8 is 13 kg / m² / h.

[0042] As shown in Figures 7-10, it can be seen that the larger the Q / S value, the greater the liquid processing volume (Flux). Furthermore, when the temperature of the liquid being processed is 60°C, as shown in Figure 8, it can be seen that a Q / S value of 0.1 or higher satisfies the first criterion, and a Q / S value of 0.25 or higher satisfies the second criterion. Also, when the temperature of the liquid being processed is 75°C, as shown in Figure 10, it can be seen that a Q / S value of 0.2 or higher satisfies the first criterion, and a Q / S value of 0.6 or higher satisfies the second criterion. Moreover, in both the cases of liquid temperatures of 60°C and 75°C, a Q / S value of 0.2 or higher satisfies the first criterion, and a Q / S value of 0.6 or higher satisfies the second criterion. From these results, it is believed that setting the Q / S value to 0.2 or higher ensures a sufficient supply of Q to the area S of the permeable surface in the separation module, and also ensures sufficient heat supply from the liquid being processed to the separation section. Therefore, the heat lost from the separation section during the evaporation of the liquid being separated from the liquid being processed can be adequately replenished, ensuring sufficient separation efficiency. Thus, it can be said that the liquid separation system of Embodiment 1, with a Q / S value controlled to 0.2 or higher, can sufficiently improve separation efficiency. Furthermore, setting the Q / S value to 0.6 or higher is considered to further improve separation efficiency.

[0043] (Experimental Example 2) In this experimental example, as shown in the graph of Figure 11, a liquid separation system with the same basic structure as in Embodiment 1 was used. While changing the supply rate Q, the relationship between the Q / S value and the pressure loss PL when the treated liquid flows through the processing liquid path was obtained. The experimental conditions were set to a temperature of 75°C for the treated liquid. Other experimental conditions were set to be the same as in Experimental Example 1.

[0044] As shown in the graph of Figure 11, it can be seen that the smaller the Q / S value, the less the pressure loss PL will be. Furthermore, when the Q / S value is below 8.8, the Reynolds number is presumably below 2300. From this result, it can be inferred that by setting the Q / S value to below 8.8, the liquid being processed flowing through the processing liquid path will not form turbulence but will form laminar flow, thereby reducing the pressure loss PL. Therefore, it is believed that by setting the Q / S value to below 8.8, the pressure loss PL can be sufficiently reduced, and both energy efficiency and separation performance can be improved. Therefore, it can be said that the liquid separation system of Embodiment 1, with a Q / S value controlled to below 8.8, can sufficiently improve both energy efficiency and separation performance. However, when the Q / S value is below 8.8, the pressure loss PL is presumably below 3 kPa.

[0045] (Experimental Example 3) In this experimental example, similar to Experimental Example 2, a liquid separation system with the same basic structure as Embodiment 1 was used. The relationship between the Q / S value and the pressure loss PL was obtained while changing the supply rate Q. Furthermore, the pressure loss PL is easily affected by the inner diameter of the processing fluid flow path, the outer diameter OD of the separable section, the length L of the separable section, and the supply rate Q. Therefore, in this experimental example, compared to the separation module used in Experimental Example 2, the inner diameter of the processing fluid flow path and the outer diameter OD of the separable section were reduced, and the length L of the separable section was increased. Under conditions that easily increase the pressure loss PL, the relationship between the Q / S value and the pressure loss PL was obtained. Specifically, the inner diameter of the processing fluid flow path was set to 0.6 mm, the outer diameter OD to 80 mm, and the length L to 0.5 m. Also, the area S of the permeable surface in the separation module was set to 2.41 m². Other experimental conditions were the same as in Experimental Example 2.

[0046] As shown in the graph of Figure 12, with a Q / S value of 4 as the boundary, compared to a Q / S value greater than 4, when the Q / S value is below 4, the pressure loss PL is significantly reduced. From this result, it is inferred that when the inner diameter, outer diameter OD, and length L of the processing fluid flow path easily increase the pressure loss PL, setting the Q / S value to below 4 can sufficiently reduce the pressure loss PL and improve both energy efficiency and separation performance. Furthermore, when the Q / S value is below 4, it is inferred that the Reynolds number becomes below 2300. From this result, it can be inferred that under conditions where the pressure loss PL easily increases, setting the Q / S value to below 4 ensures that the treated fluid flowing through the processing fluid flow path does not form turbulence but rather laminar flow, thereby reducing the pressure loss PL. However, when the Q / S value is below 4, the pressure loss PL becomes below 50 kPa.

[0047] (Embodiment 2) This embodiment, as shown in FIG13, is an embodiment having 6 separation modules 2. That is, the liquid separation system 1 of this embodiment has a plurality of separation modules 2. The plurality of separation modules 2 are arranged such that the flow direction FD is the same as each other, and when viewed from the flow direction FD (figure omitted), they are arranged to overlap each other.

[0048] In this embodiment, a plurality of separation modules 2 are housed within a frame 6. The frame 6 is connected to a supply flow path (omitted in the figure, refer to symbol 52 in Figure 1), an outlet flow path (omitted in the figure, refer to symbol 52a in Figure 1), and a recovery flow path (omitted in the figure, refer to symbol 54 in Figure 1). An inlet-side opening 61, connecting the outside and the inside of the frame 6, is provided at one end of the frame 6 in the flow direction FD, and is connected to the supply flow path. Similarly, an outlet-side opening 62, connecting the outside and the inside of the frame 6, is provided at the other end of the frame 6 in the flow direction FD, and is connected to the outlet flow path. In the flow direction FD, a plurality of separation modules 2 are disposed between the inlet-side opening 61 and the outlet-side opening 62. The liquid to be processed, as shown by arrow FL3 in Figure 13, flows from the supply flow path into the frame 6 via the inlet-side opening 61. Next, the liquid being processed flows from the inlet side opening 61 to the outlet side opening 62, passing through a plurality of separation modules 2 one by one, and is discharged as a concentrate to the outlet flow path through the outlet side opening 62.

[0049] Furthermore, a plurality of vapor outlet openings 63 are provided on the outer periphery of the frame 6, connecting the outside and the inside of the frame 6, and are connected to the recovery flow path. The vapor separated from the liquid being processed by the separation module 2 is discharged to the recovery flow path through the plurality of vapor outlet openings 63, as shown by arrow FL2 in FIG13.

[0050] Furthermore, annular sealing portions 64 are provided between the outer peripheries of the frame 6 and the separation module 2, and between the outer peripheries of two adjacent separation modules 2 in the flow direction FD. This prevents the treated liquid from flowing into the recovery path via the vapor outlet opening 63. The sealing portion 64 can be, for example, fluororubber, silicone rubber, or nitrile rubber. Everything else is the same as in Embodiment 1. In addition, in Embodiment 2 and thereafter, unless otherwise specified, the symbols that are the same as those used in the existing embodiments indicate the same constituent elements as in the existing embodiments.

[0051] The liquid separation system 1 of this embodiment has a plurality of separation modules 2. The plurality of separation modules 2 are arranged such that their flow directions FD are the same and they overlap each other when viewed from the flow direction FD. Therefore, the area S of the permeable surface can be easily increased, thereby further improving the separation efficiency. In addition, it has the same effect as in Embodiment 1.

[0052] In Embodiment 2 described above, six separation modules 2 are housed in the frame 6. However, for example, two to five separation modules may also be housed in the frame, and seven or more separation modules may also be housed. Furthermore, the liquid separation system may also be configured such that, for example, a liquid being processed is processed by using a plurality of frames that house the plurality of separation modules described in Embodiment 2 in an inner arrangement, connected in a straight line or in parallel.

[0053] (Embodiment 3) This embodiment is a configuration for controlling a specific relationship with respect to the flow rate of the liquid being treated, d. Since the basic structure of this embodiment is the same as that of Embodiment 1, it will be described with reference to FIG. 1 of Embodiment 1.

[0054] In this embodiment, the temperature of the liquid to be processed, d, supplied to the processing liquid flow path 41 is higher than the temperature of the separation section 21. Furthermore, the flow rate of the liquid to be processed, d, supplied to the separation module 2 is a flow rate V m / s. In this embodiment, the specific relationship in the liquid separation system 1 is the relationship between the flow rate V and the length L. In this embodiment, the liquid separation system 1 is controlled by the control unit 3 to have a V / L value of 0.05 to 2.5, which is the ratio of the flow rate V to the length L.

[0055] In this embodiment, the control unit 3 controls the pump 51 installed in the supply flow path 52 to adjust the flow rate V. In this way, the control unit 3 adjusts the heat supplied to the separation unit 21 and controls a specific relationship. Everything else is the same as in Embodiment 1.

[0056] In this embodiment, the liquid separation system 1 is controlled by the control unit 3 to have a V / L value of 0.05 to 2.5. Therefore, separation efficiency, energy efficiency, and separation performance can be significantly improved. Specifically, although the longer the length L of the separable section, the easier it is to increase the area S of the through surface 211, and the easier it is to increase the area of ​​the separated liquid Lq that can be separated from the processed liquid d, the more likely it is to lose heat from the separation section 21. Therefore, in this embodiment, the liquid separation system 1 is controlled to have a V / L value of 0.05 or higher. Therefore, even if the heat lost from the separation section 21 due to the evaporation of the separated liquid Lq increases, the lost heat can be compensated by increasing the flow rate V, and the heat supplied to the separation section 21 can be increased to suppress the decrease in liquid throughput Flux caused by the temperature drop of the separation section 21. More specifically, by setting the V / L value to 0.05 or higher, the flow rate V can be sufficiently ensured for the length L, and the heat supplied to the separation section 21 from the processed liquid d at a higher temperature can be sufficiently ensured. Therefore, the temperature drop of the separation section 21 can be suppressed, and the separation efficiency can be fully ensured. While setting the V / L value higher increases the flow rate V, making it easier to suppress the temperature drop of the separation section 21, it also tends to increase the pressure loss when the treated liquid d flows through the processing liquid flow path 41. Furthermore, if the V / L value is set too high, there are concerns about the treated liquid d passing through the separation section 21, and a decrease in the separation performance of the separation module 2. Therefore, in this embodiment, the V / L value is set to 2.5 or lower. This suppresses the pressure loss when the treated liquid d flows through the processing liquid flow path 41. As a result, both energy efficiency and separation performance are significantly improved. Furthermore, it has the same effects as Embodiment 1.

[0057] (Experimental Example 4) In this experimental example, as shown in Figures 14 and 15, a liquid separation system with the same basic structure as in Embodiment 1 was used. The relationship between the V / L value and the liquid throughput (Flux) was obtained by changing the flow rate V. The experimental conditions were that the temperature of the liquid to be treated was set to 75°C. Other experimental conditions were the same as in Experimental Example 1.

[0058] As shown in the graph of Figure 14, when the V / L value is 1.4 or higher, the liquid throughput Flux reaches saturation. Furthermore, in this experimental example, as shown in the graph of Figure 15, the case where the liquid throughput Flux is 50% or higher when the V / L value is 1.4 is used as the third benchmark, which is a benchmark with better separation efficiency. Therefore, the V / L value that satisfies this benchmark was obtained from the results of this experimental example. However, the liquid throughput Flux when the V / L value is 1.4 is 13 kg / m² / h. Also, the graph of Figure 15 shows an approximate curve of the experimental results.

[0059] From the approximate curve shown in Figure 15, it can be seen that the third criterion is met when the V / L value is 0.047 or higher. As a result, when the Q / S value is set to 0.05 or higher, it is considered that a sufficient flow rate V can be ensured for the length L of the separable section, and sufficient heat can be supplied from the treated liquid to the separation section. Therefore, it is considered that sufficient heat can be replenished when the separated liquid evaporates from the treated liquid, thus ensuring sufficient separation efficiency. Therefore, it can be said that the liquid separation system of Embodiment 3, with a V / L value controlled to 0.05 or higher, can sufficiently improve separation efficiency.

[0060] (Experimental Example 5) In this experimental example, as shown in the graph of Figure 16, a liquid separation system with the same basic structure as in Embodiment 1 was used. While changing the flow rate V, the relationship between the V / L value and the pressure loss PL was obtained. Other experimental conditions were the same as in Experimental Example 2.

[0061] As shown in the graph of Figure 16, it can be seen that the smaller the V / L value, the less the pressure loss PL. Furthermore, when the V / L value is below 1.7, the Reynolds number is presumably below 2300. From these results, it can be inferred that by setting the V / L value to below 1.7, the treated liquid flowing through the processing liquid path will not form turbulence but rather laminar flow, thereby reducing the pressure loss PL. Therefore, it is believed that setting the V / L value to below 1.7 can improve both energy efficiency and separation performance. However, when the Q / S value is below 1.7, the pressure loss PL is presumably below 3 kPa.

[0062] (Experimental Example 6) In this experimental example, similar to Experimental Example 5, a liquid separation system with the same basic structure as Embodiment 1 was used. While changing the flow rate V, the relationship between the V / L value and the pressure loss PL was obtained. Furthermore, in this experimental example, the relationship between the V / L value and the pressure loss PL was obtained under the condition that the pressure loss PL easily increases. Specifically, the inner diameter, outer diameter OD, and length L of the processed liquid flow path were included, and the experimental conditions were set to be the same as in Experimental Example 3.

[0063] As shown in the graph of Figure 17, it is speculated that with a V / L value of 2.5 as the boundary, compared with a V / L value greater than 2.5, a V / L value below 2.5 results in a significant reduction in pressure loss PL. Based on this result, it is speculated that when the inner diameter, outer diameter OD, and length L of the processing fluid flow path easily increase pressure loss PL, setting the V / L value below 2.5 can sufficiently reduce pressure loss PL and improve both energy efficiency and separation performance. Furthermore, when the V / L value is below 2.5, it is speculated that the Reynolds number becomes below 2300. From this result, it can be inferred that when the inner diameter, outer diameter OD, and length L of the processing fluid flow path easily increase pressure loss PL, setting the V / L value below 2.5 ensures that the treated fluid flowing through the processing fluid flow path does not form turbulence but rather laminar flow, thereby reducing pressure loss PL. However, when the V / L value is below 2.5, the pressure loss PL becomes below 50 kPa.

[0064] In embodiments 1 to 3 described above, the concentrate d flowing through the outlet flow path 52a is returned to the discharge tank 57. However, the concentrate discharged from the separation module can be further processed, for example, by being sent to a crystallization apparatus for crystallizing substances containing the concentrate.

[0065] Furthermore, the liquid to be processed supplied to the separation module may be wastewater after various treatments, such as oil separation, biological treatment, coagulation treatment, or salt removal treatment by the separation membrane. Also, the liquid to be processed may be, for example, wastewater discharged from electroplating or coating processes, in addition to wastewater.

[0066] Furthermore, the liquid being treated may be, for example, a liquid containing water, and the liquid being separated may be, for example, water. Also, the liquid separation system may be used to separate water from, for example, seawater or brine, which is the liquid being treated. Furthermore, the liquid separation system may also be configured to treat acidic or alkaline liquids.

[0067] Furthermore, the liquid to be separated may be, for example, water, an organic solvent (methanol, ethanol, isopropanol, acetonitrile, acetone, ethylene glycol, benzene, toluene, etc.), or may contain two or more of these liquids. Furthermore, the separation unit may separate not only these liquids, but also ammonia and the like from the liquid being processed. Furthermore, the liquid being processed may contain one or more of these liquids, and may also contain ammonia and the like.

[0068] In embodiments 1 to 3 described above, the liquid separation system 1 performs membrane distillation while the vacuum pump 53 reduces pressure. However, membrane distillation can also be performed without using a vacuum pump. That is, the temperature of the liquid to be processed is set to a specific designated temperature or higher, and a temperature difference is established between the liquid flow path and the vapor flow path. In this way, a vapor pressure difference is generated on both sides of the separation section facing the two flow paths, and the liquid to be separated can be separated from the liquid to be processed. Furthermore, the separation section can also be adapted, for example, to a separation module using a so-called gas-gap membrane distillation method, which provides a vapor flow path as a gas gap between the liquid flow path and the refrigerant flow path for refrigerant circulation.

[0069] Furthermore, the liquid separation system may, for example, separate the liquid to be separated from the liquid to be processed by a permeation vaporization method, in addition to the membrane distillation method described above.

[0070] In the above embodiments 1 to 3, the flow path shapes of the processing liquid flow path 41 and the vapor flow path 42 are quadrilateral when viewed from the axial direction x. However, the flow path shapes of the processing liquid flow path and the vapor flow path can be, for example, polygonal shapes such as hexagons, circular shapes, or other arbitrary shapes when viewed from the axial direction.

[0071] In embodiments 1 to 3 described above, the separation module has a honeycomb structure. However, the separation module is not limited to a honeycomb structure and various other structures may be used. For example, the separation module may also be configured to have a processing liquid flow path and a vapor flow path respectively.

[0072] In embodiments 1 and 2 described above, the Q / S value is controlled, and in embodiment 3 described above, the V / L value is controlled. However, the liquid separation system may, for example, set the specific relationship as the relationship between the temperature of the liquid being processed supplied to the separation module and the area of ​​the permeation surface. Furthermore, the liquid separation system may also be configured to control a plurality of specific relationships.

[0073] Furthermore, the liquid separation system may also control a specific relationship based on the amount of the processed liquid discharged from the separation module per unit time.

[0074] In embodiments 1 to 3 described above, heat is supplied from the liquid being processed to the separation section. However, the liquid separation system may also be configured such that heat is supplied to the separation module or separation section by controlling a heater or heat exchanger with a control unit. In this case, for example, a specific relationship may be set as the relationship between the heat supplied to the separation section by the heater or heat exchanger and the area of ​​the permeable surface.

[0075] In embodiments 1 to 3 described above, the separation module 2 has a cylindrical shape. However, the separation module is not limited to a cylindrical shape. For example, it may be made into a quadrangular prism shape or a triangular prism shape so that the cross-section along the flow direction is quadrangular or triangular.

[0076] The present invention is not limited to the above embodiments, and can be applied to various other embodiments without departing from its spirit. [Simplified Explanation of the Diagram]

[0009] [Figure 1] is a conceptual diagram of the liquid separation system in Embodiment 1. [Figure 2] is a front view and cross-sectional view of the separation module in Embodiment 1. [Figure 3] is a perspective view of the separation module in Embodiment 1. [Figure 4] is a cross-sectional view showing the processing liquid flow path and vapor flow path of the separation module in Embodiment 1. [Figure 5] is an enlarged cross-sectional view of the processing liquid flow path in Embodiment 1 as seen from the flow direction. [Figure 6] is a cross-sectional view of the separation section in Embodiment 1. [Figure 7] is a graph showing the relationship between the Q / S value and the liquid processing volume (Flux) when the temperature of the liquid being processed in Experimental Example 1 is 60°C. [Figure 8] is a graph showing the relationship between the Q / S value and the liquid processing volume (Flux) when the temperature of the liquid being processed in Experimental Example 1 is 60°C, and also a graph showing the Q / S values ​​that meet the first and second criteria. [Figure 9] is a graph showing the relationship between the Q / S value and the liquid processing volume (Flux) when the temperature of the liquid being processed in Experimental Example 1 is 75°C. [Figure 10] is a graph showing the relationship between the Q / S value and the fluid throughput (Flux) when the temperature of the treated liquid is 75°C in Experimental Example 1, and also a graph showing the Q / S values ​​that meet the first and second criteria. [Figure 11] is a graph showing the relationship between the Q / S value and the pressure loss (PL) in Experimental Example 2. [Figure 12] is a graph showing the relationship between the Q / S value and the pressure loss (PL) in Experimental Example 3. [Figure 13] is a cross-sectional view showing the plurality of separation modules housed in the frame in Embodiment 2. [Figure 14] is a graph showing the relationship between the V / L value and the fluid throughput (Flux) in Experimental Example 4. [Figure 15] is a graph showing the relationship between the V / L value and the fluid throughput (Flux) in Experimental Example 4, and also a graph showing the V / L value that meets the third criterion. [Figure 16] is a graph showing the relationship between the V / L value and the pressure loss (PL) in Experimental Example 5. [Figure 17] is a graph showing the relationship between the V / L value and the pressure loss (PL) in Experimental Example 6.

Claims

1. A liquid separation system (1) comprising a separation module (2) for separating a liquid to be separated (Lq) from a liquid to be processed (d), the separation module comprising: a separation section (21) having a ceramic substrate (22) having a plurality of fine holes (20) for separating the liquid to be separated from the liquid to be processed by allowing the liquid to be separated, which is contained in the liquid to be processed, to pass through in a vapor (v) state; and a processing liquid flow path (41) for the liquid to be processed to flow through, the separation section having a permeable surface (211) facing the processing liquid flow path and allowing the vapor to pass through, and a control section (3) for controlling a specific relationship, the specific relationship being the relationship between the heat supplied to the separation section and the heat removed from the separation section due to the evaporation of the liquid to be separated contained in the liquid to be processed, the control section controlling the specific relationship to separate the liquid to be separated from the liquid to be processed. The temperature of the liquid to be processed supplied to the aforementioned processing liquid flow path is higher than the temperature of the aforementioned separation section. The aforementioned specific relationship is the relationship between the supply amount Qm3 / h of the liquid to be processed supplied to the aforementioned separation module per unit time and the area Sm2 of the aforementioned permeable surface. The aforementioned control unit controls the aforementioned specific relationship by adjusting the aforementioned supply amount Q. The aforementioned control unit controls the Q / S value, which is the ratio of the aforementioned supply amount Q to the area S of the aforementioned permeable surface, to be 0.2 to 8.

8.

2. The liquid separation system as described in claim 1, wherein, The aforementioned control unit controls the Q / S value to be between 0.6 and 4.

0.

3. A liquid separation system (1) comprising a separation module (2) for separating a liquid to be separated (Lq) from a liquid to be processed (d), the separation module comprising: a separation section (21) having a ceramic substrate (22) having a plurality of fine holes (20) for separating the liquid to be separated from the liquid to be processed by allowing the liquid to be separated, which is contained in the liquid to be processed, to pass through in a vapor (v) state; and a processing liquid flow path (41) for the liquid to be processed to flow through, the separation section having a permeable surface (211) facing the processing liquid flow path and allowing the vapor to pass through, and a control section (3) for controlling a specific relationship, the specific relationship being the relationship between the heat supplied to the separation section and the heat removed from the separation section due to the evaporation of the liquid to be separated contained in the liquid to be processed, the control section controlling the specific relationship to separate the liquid to be separated from the liquid to be processed. When the temperature of the liquid to be processed supplied to the aforementioned processing liquid flow path is higher than the temperature of the aforementioned separation section, and the flow rate of the liquid to be processed supplied to the aforementioned separation module is a flow rate Vm / s, and the direction along which the liquid to be processed flows through the aforementioned processing liquid flow path is taken as the flow direction (FD), and the length of the flow direction of the separable section (25) in the aforementioned separation module that can separate the liquid to be separated from the liquid to be processed is taken as the length Lm, the aforementioned specific relationship is the relationship between the aforementioned flow rate V and the aforementioned length L. By the aforementioned control unit, the V / L value, which is the ratio of the aforementioned flow rate V to the aforementioned length L, is controlled to be 0.05 to 2.

5.

4. The liquid separation system described in any one of claims 1 to 3, wherein, The aforementioned separation module has a cylindrical shape. The direction along which the liquid to be processed flows is taken as the flow direction (FD). When the length of the flow direction of the separable part (25) in the aforementioned separation module that can separate the liquid to be separated from the liquid to be processed is taken as the length Lm, the aforementioned length L is 0.05~1.00m. The outer diameter (OD) of the aforementioned separable part when viewed from the aforementioned flow direction is 80~265mm.

5. The liquid separation system described in any one of claims 1 to 3, having a plurality of the aforementioned separation modules, wherein the flow direction (FD) is the direction in which the liquid to be processed flows through the aforementioned processing liquid path, the plurality of the aforementioned separation modules are configured such that the aforementioned flow direction is the same as each other, and are configured to overlap each other when viewed from the aforementioned flow direction.

6. The liquid separation system described in any one of claims 1 to 3, wherein, The aforementioned ceramic substrate is composed of porous ceramic and contains at least one selected from aluminum, mullite, silicon dioxide, silicon carbide, zirconium oxide, and cordierite.

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