Liquid-liquid extraction device

Abstract

A multi-tower liquid-liquid extraction device with multiple extraction towers is characterized in that n (n is an integer greater than 2) extraction towers are arranged side by side, each extraction tower has a heavy liquid supply section on the top side and a heavy liquid discharge section on the bottom side, and also has a light liquid supply section on the bottom side and a light liquid discharge section on the top side, the heavy liquid flow paths of the n extraction towers are connected in series, and at least two of the n extraction towers are connected to their respective diaphragm chambers by their respective pipes, the diaphragm chambers have closed spaces, part of their walls are formed by diaphragms and their volume is changed by an operating drive, and the pipes between each extraction tower and its respective diaphragm chamber are equipped with a pressure regulating chamber and an on / off valve for adjusting the internal pressure.

Description

Technical Field

[0001] The present invention relates to a liquid-liquid extraction device, in particular to a liquid-liquid extraction device having a relatively low extraction tower height, fewer restrictions on installation locations, a relatively simple structure, and the ability to perform extraction efficiently. Prior Art

[0002] Liquid-liquid extraction (LIFE) involves extracting a desired substance by transferring a solute dissolved in a solvent into another solvent for separation and purification. This type of LLE has the following issues: Its efficiency is lower than that of separation methods such as distillation, adsorption, and absorption from the perspective of substance transfer. Furthermore, due to the increased contact efficiency and time between liquids, the extraction column used is relatively tall, limiting its installation.

[0003] Furthermore, from the perspective of the above-mentioned material transfer, a mixer-settler type extraction column has been developed that improves efficiency and has an operating section such as an MS column of a continuous extraction device and a Karr column that operates the tray itself.

[0004] Because these extraction devices have operating components within the tower, they are complex and present maintenance and cost challenges. Meanwhile, packed towers for liquid-liquid extraction are simple structures filled with a filler, offering advantages in terms of maintenance and cost, but they also suffer from lower liquid-liquid contact efficiency.

[0005] Furthermore, as disclosed in Patent Documents 1 (Japanese Patent Application Laid-Open No. 5-192505), 2 (Japanese Patent Application Laid-Open No. 5-337304), and 3 (Japanese Patent Application Laid-Open No. 7-31803), pulsating towers are also widely known as solvent extraction devices primarily used for atomic raw material circulation. Pulsating towers offer the advantages of continuous operation and a short solvent residence time within the tower, thus minimizing radiation damage to the solvent. However, while prior pulsating (beating) packed towers offer excellent performance, they suffer from the problem of flooding and a narrow operating range due to the pulsating motion of the entire tower interior.

[0006] For example, Patent Document 4 (Japanese Patent Application Laid-Open No. 2018-15754) discloses a structure in which a diaphragm pump is installed outside the treatment tower to apply pulsation to the treatment tower. One of the discharge or intake ports of the diaphragm pump is shielded, and the other is connected to the interior of the treatment tower, causing reciprocating motion of the fluid within the treatment tower. This discloses a liquid-liquid extraction device that uses an external diaphragm pump to generate pulsation, thereby reducing equipment costs by a simple method compared to conventional pulsation towers. However, even liquid-liquid extraction devices using this diaphragm pump have unresolved issues: increased contact efficiency and retention time between the liquids, as described above, increase the height of the extraction tower, and impose installation restrictions. Furthermore, the device disclosed in Patent Document 4 presents the following problem: while the diaphragm pump capacity is selected based on the desired pulse amplitude multiplied by the internal cross-sectional area of ​​the pulsation tower, this cannot be adjusted due to the lack of adjustment margin for the diaphragm amplitude, making overflow more likely to occur depending on the extraction system. Summary of the Invention

[0007] Therefore, the present invention aims to provide a liquid-liquid extraction apparatus that solves the problems existing in the above-mentioned conventional technology. Another object of the present invention is to provide a liquid-liquid extraction apparatus that maintains a low extraction tower height, reduces installation site restrictions, has a relatively simple structure, and enables efficient extraction.

[0008] The present invention for solving the above-mentioned problems is a multi-tower liquid-liquid extraction apparatus having a plurality of extraction towers, characterized in that n (n is an integer greater than or equal to 2) extraction towers are arranged side by side, each extraction tower having a heavy liquid supply portion at the tower top side and a heavy liquid discharge portion at the tower bottom side, and further having a light liquid supply portion at the tower bottom side and a light liquid discharge portion at the tower top side; (a) the heavy liquid discharge portion of the first extraction tower among the n extraction towers is connected to the heavy liquid supply portion of the second extraction tower via a pipeline, the heavy liquid discharge portion of the second extraction tower is connected to the heavy liquid supply portion of the third extraction tower via a pipeline, ... the heavy liquid discharge portion of the (n-1)th extraction tower is connected to the heavy liquid supply portion of the nth extraction tower via a pipeline, and in this manner, the heavy liquid flow paths of the n extraction towers are connected in series; and / or Or, (b) the light liquid discharge portion of the nth extraction tower among the n extraction towers is connected to the light liquid supply portion of the (n-1)th extraction tower via a pipeline, the light liquid discharge portion of the (n-1)th extraction tower is connected to the light liquid supply portion of the (n-2)th extraction tower via a pipeline, ... the light liquid discharge portion of the second extraction tower is connected to the light liquid supply portion of the first extraction tower via a pipeline, and in this way the light liquid flow paths of the n extraction towers are connected in series; and at least two of the n extraction towers are connected to their respective diaphragm cavities via their respective pipelines, the diaphragm cavities having a closed space, part of whose wall surface is formed by a diaphragm and whose volume is changed by an operating drive unit; the pipeline between each extraction tower and its respective diaphragm cavity is provided with a pressure regulating chamber and an on-off valve for regulating the internal pressure.

[0009] In one embodiment of the liquid-liquid extraction apparatus of the present invention, the following configuration is illustrated: the diaphragm chamber comprises two chamber sections, each of which is comprised of a diaphragm forming a wall surface of each chamber, and is driven electrically or by compressed air. The check valves at the inlet and outlet of the diaphragm pump are removed, and the outlet of one chamber section and the inlet of the other chamber section are sealed with a partition. Each chamber section has only one liquid flow path, and each chamber section uses an improved diaphragm pump equipped with a degassing nozzle, with the pipelines of the two extraction towers connected to the diaphragm pumps respectively.

[0010] In one embodiment of the liquid-liquid extraction device of the present invention, the following aspect is shown, wherein the n extraction towers are two extraction towers.

[0011] In one embodiment of the liquid-liquid extraction apparatus of the present invention, the amplitude of the extraction apparatus is adjusted by the pressure difference between the pressure at any location within each extraction column, calculated from the average density and liquid level of the liquid within the column, and the pressure within the pressure regulating chamber.

[0012] In one embodiment of the liquid-liquid extraction apparatus of the present invention, the pulsation of the extraction apparatus can be performed by adjusting the pressure in the pressure regulating chamber and opening and closing the valve to pulsate only one of the towers.

[0013] In one embodiment of the liquid-liquid extraction device of the present invention, the following aspect is shown, in which the pulsation of the extraction device can change the amplitude according to each extraction column by individually adjusting the pressure in the pressure regulating chamber.

[0014] In one embodiment of the liquid-liquid extraction device of the present invention, the following state is shown, which is characterized in that each extraction tower has a gas-liquid interface at the top of the tower, and is connected respectively by a pressure equalizing pipe at the top of the tower, so that the pressure in the tower is uniform.

[0015] In one embodiment of the liquid-liquid extraction apparatus of the present invention, the following aspect is shown, characterized in that among the extraction towers, the n extraction towers are three or more extraction towers, three or more adjacent extraction towers are connected separately, or any two or more towers are connected to the above-mentioned improved diaphragm pump via pipelines.

[0016] [Effects of the Invention]

[0017] The liquid-liquid extraction apparatus of the present invention is a multi-tower liquid-liquid extraction apparatus having multiple extraction towers. Since the multiple extraction towers are arranged side by side, even if the contact efficiency and retention time between the liquids need to be increased, the height is lower than that of a single-tower extraction tower, making it easier to install in existing equipment. Furthermore, in the liquid-liquid extraction device of the present invention, the pulsator is not a complicated one and can be improved by using an existing diaphragm pump, which is more economical.

[0018] Furthermore, in the liquid-liquid extraction apparatus of the present invention, the connection points between the pipes connecting the multiple extraction towers and the respective diaphragm chambers can be installed at any desired location for pulsation. Furthermore, the pulsation amplitude and frequency can be arbitrarily adjusted, and pulsation can be applied to only one tower. Therefore, for example, in a system where the concentration gradient in the first tower is large and material transfer is likely to occur, pulsation can be omitted from the first tower and applied only to the second tower, thereby achieving efficient extraction and saving power for the pulsator.

[0019] Furthermore, in the liquid-liquid extraction apparatus of the present invention, for example, even if the characteristics of the solution to be treated change, the extraction efficiency can be improved by applying pulsation to the first tower to cope with the change. Furthermore, the liquid-liquid extraction device of the present invention can also be applied to the modification of an existing extraction tower by introducing a diaphragm chamber serving as a pulsator from the outside of the extraction tower.

[0020] Furthermore, in the liquid-liquid extraction apparatus of the present invention, for example, in a system where liquids easily mix and the difference in specific gravity between the light liquid and the heavy liquid is small, in order to suppress overflow where droplets do not drip or rise, or in a system where the amplitude is reduced and the difference in specific gravity between the light liquid and the heavy liquid is large, in order to suppress excessive transfer of droplets, the amplitude can be increased and the frequency can be adjusted faster, thus having a wide range of applicable systems.

[0021] Furthermore, in the liquid-liquid extraction apparatus of the present invention, for example, in a system where the amount of material transferred in the first column is large, the liquid flow rate in the first column is larger than that in the second column. Therefore, from the perspective of preventing overflow, it is possible to change the amplitude of the first and second columns or to stop the amplitude of only the first column.

[0022] Furthermore, in the liquid-liquid extraction apparatus of the present invention, by adding an extraction column and introducing the same system, the performance can be improved only by additional construction of the existing apparatus. Furthermore, in the liquid-liquid extraction apparatus of the present invention, for example, since the diaphragm chamber serving as a pulsator is installed outside the extraction column, maintenance is easy, and since there are no operating parts such as a Karr column or RDC inside the extraction column, it is easy to deal with any problems that occur.

[0023] Furthermore, when using extraction towers in various systems, multiple pipes and valves can be installed branching from the pulsator to pre-apply pulsation to the extraction tower. Depending on the system, the location of pulsation can be arbitrarily selected by operating the valves, and the amplitude of each pulsation can be freely controlled.

[0024] Furthermore, since the pulsators connected to the two towers do not mix the liquids in the pulsators, one or more towers can be used to perform the forward extraction for component separation and the back extraction for separating the extracted substance from the extractant.

[0025] In order to make the above and other objects, features and advantages of the present invention more clearly understood, embodiments are given below and described in detail with reference to the accompanying drawings. Simple diagram description

[0026] FIG1 is a schematic diagram showing the overall structure of a liquid-liquid extraction device according to one embodiment of the present invention. FIG2 is a schematic diagram of an improved diaphragm chamber structure used in an embodiment of a liquid-liquid extraction device of the present invention. Implementation Method

[0027] The present invention will be described in more detail below based on embodiments.

[0028] FIG1 is a schematic diagram of the overall structure of an embodiment of a liquid-liquid extraction device of the present invention, and FIG2 is a schematic diagram of the improved diaphragm chamber structure used in an embodiment of a liquid-liquid extraction device of the present invention.

[0029] The liquid-liquid extraction apparatus of the present invention is a multi-tower liquid-liquid extraction apparatus having multiple extraction towers, wherein n (n is an integer greater than or equal to 2) extraction towers are arranged side by side. The embodiment shown in FIG1 illustrates a configuration example in which two (n=2) extraction towers 10 and 20 are arranged side by side, representing the minimum configuration of the multi-tower liquid-liquid extraction apparatus 1 of the present invention. However, the number of extraction towers (n) in the liquid-liquid extraction apparatus 1 of the present invention can naturally be three or more. Furthermore, while not particularly limited, the number n is typically, for example, 2 to 4, more preferably 2 to 3. Thus, even when increasing liquid contact efficiency and retention time, the height of the multiple extraction towers is lower than that of a single-tower extraction tower, making it easier to install within existing equipment. Furthermore, in this specification, the term "side by side arrangement" broadly refers to the arrangement of the extraction towers side by side relative to the installation surface, assuming a given installation location, and does not simply mean that their positions, spacing, angles, etc. are completely aligned. Furthermore, the "setting surface" is also usually composed of a horizontal surface, but it can also be, for example, a surface with steps or a surface with curvature, or even a setting surface that can be divided into multiple layers.

[0030] Therefore, since multiple extraction towers are arranged side by side, even if it is necessary to increase the contact efficiency and residence time between liquids, the height is lower than that of a single-tower extraction tower, making it easier to install in existing equipment.

[0031] In the liquid-liquid extraction apparatus of the present invention, each extraction tower has a heavy liquid supply unit at the top and a heavy liquid discharge unit at the bottom, and also has a light liquid supply unit at the bottom and a light liquid discharge unit at the top. In the embodiment shown in FIG1 , each extraction tower 10 or 20 is provided with a spray nozzle 14 or 24 serving as the heavy liquid supply unit and an overflow nozzle 16 or 26 serving as the light liquid discharge unit above the packing 12 or 22 disposed within the tower (tower top side). A nozzle 15 or 25 serving as the light liquid supply unit and a drain pipe 17 or 27 serving as the heavy liquid discharge unit are provided in the hollow portion of the tower bottom below the packing (tower bottom side). The shape and exact placement of each supply unit and each discharge unit are not particularly limited, as long as the extraction tower effectively functions.

[0032] In order to fully utilize the multi-tower structure in the liquid-liquid extraction apparatus of the present invention, the following conditions must be met: (a) the heavy liquid discharge portion of the first extraction tower among n extraction towers is connected to the heavy liquid supply portion of the second extraction tower via a pipeline, the heavy liquid discharge portion of the second extraction tower is connected to the heavy liquid supply portion of the third extraction tower via a pipeline, ... the heavy liquid discharge portion of the (n-1)th extraction tower is connected to the heavy liquid supply portion of the nth extraction tower via a pipeline, and in this manner the heavy liquid flow paths of the n extraction towers are connected in series; and / or, (b) The light liquid discharge portion of the nth extraction tower among the n extraction towers is connected to the light liquid supply portion of the (n-1)th extraction tower via a pipeline, the light liquid discharge portion of the (n-1)th extraction tower is connected to the light liquid supply portion of the (n-2)th extraction tower via a pipeline, ... the light liquid discharge portion of the second extraction tower is connected to the light liquid supply portion of the first extraction tower via a pipeline, and in this way the light liquid flow paths of the n extraction towers are connected in series.

[0033] In the embodiment shown in FIG1, this point is explained. (a) The heavy liquid discharge portion (drain pipe) 17 of the first extraction tower 10 of the two extraction towers 10 and 20 is connected to the heavy liquid supply portion (spray nozzle) 24 of the second extraction tower via a pipe 32, thereby connecting the heavy liquid flow paths of the two extraction towers in series. (b) The light liquid discharge portion (overflow nozzle) 26 of the second extraction tower 20 of the two extraction towers 10 and 20 is connected to the light liquid supply portion (nozzle) 15 of the first extraction tower 10 via a pipe 34, thereby connecting the light liquid flow paths of the two extraction towers in series.

[0034] In the embodiment shown in FIG1 , both the heavy liquid flow path (a) and the light liquid flow path (b) are connected in series. However, depending on the type of target substance to be obtained in the extraction operation, only one of the heavy liquid flow path (a) or the light liquid flow path (b) may be connected in series.

[0035] 1 , reference numeral 82 denotes a heavy liquid tank, reference numeral 84 denotes a light liquid tank, and reference numeral 86 denotes a light liquid buffer tank.

[0036] Furthermore, in the liquid-liquid extraction apparatus of the present invention, in an embodiment in which one or more towers are used to respectively perform forward extraction for component separation and back extraction for separating the extracted substance from the extractant, the number of extraction towers (n) in the above conditions (a) and (b) is set to a value smaller than the total number (N) of extraction towers in the entire liquid-liquid extraction apparatus, so as to satisfy the series connection structure of the heavy liquid flow path and / or the light liquid flow path.

[0037] Furthermore, in the liquid-liquid extraction apparatus of the present invention, at least two of the n extraction towers 10, 20 are connected to respective diaphragm chambers 44, 54 via respective pipes 42, 52. The diaphragm chambers have enclosed spaces, part of whose walls are formed by diaphragms and whose volumes are changed by operating a driving unit. The pipes 42 , 52 between the extraction columns 10 , 20 and the respective diaphragm chambers 44 , 54 are provided with pressure regulating chambers 46 , 56 and on-off valves 48 , 58 for regulating the internal pressure.

[0038] Therefore, in one embodiment of the liquid-liquid extraction apparatus of the present invention, the pulsation of the extraction apparatus can be adjusted by adjusting the pressure in the pressure regulating chambers 46, 56 and the opening and closing valves 48, 58 to pulsate only one of the towers. Furthermore, by adjusting the pressure in the pressure regulating chambers 46, 56 separately, pulsation can be applied to each extraction tower 10, 20 separately.

[0039] Therefore, in the liquid-liquid extraction device of the present invention, for example, in a system where liquids are easily mixed and the difference in specific gravity between the light liquid and the heavy liquid is small, in order to suppress overflow where droplets do not drip or rise, and in a system where the amplitude is reduced and the difference in specific gravity between the light liquid and the heavy liquid is large, in order to suppress excessive transfer of droplets, the amplitude can be increased so that the frequency is also faster, thereby having a wide range of applicable systems.

[0040] Furthermore, in the liquid-liquid extraction apparatus of the present invention, for example, in a system where the amount of material transferred in the first column 10 is large, the liquid flow rate in the first column is larger than that in the second column 20. Therefore, from the perspective of preventing overflow, it is possible to change the amplitude of the first and second columns or to stop the amplitude of only the first column.

[0041] Furthermore, in the embodiment shown in FIG1 , since the liquid-liquid extraction apparatus comprises only two extraction towers 10 and 20 arranged side by side, both extraction towers 10 and 20 are connected to diaphragm chambers 44 and 54 via pipes 42 and 52. However, in embodiments of the liquid-liquid extraction apparatus of the present invention where the number n of extraction towers is three or more, it is not necessary for all extraction towers to be connected to the diaphragm chambers. Alternatively, at least two of the three or more extraction towers may be connected to the diaphragm chambers. Specifically, in another embodiment of the liquid-liquid extraction apparatus of the present invention, the n extraction towers comprise three or more extraction towers, adjacent extraction towers comprise three or more towers, or any two or more towers are connected to the improved diaphragm pump via pipes. This is because, in the liquid-liquid extraction apparatus of the present invention, as long as a structure capable of applying pulsation to the diaphragm chambers of at least two of the multiple extraction towers arranged side by side is used, the desired effect can be achieved.

[0042] In the liquid-liquid extraction apparatus of the present invention, the diaphragm chambers 44 and 54 that apply pulsation to each extraction column 10 and 20 are not particularly limited, as long as they comprise a closed space with a portion of its wall formed by a diaphragm, whose volume is changed by an operating drive unit, and capable of applying pulsation to each extraction column 10 and 20. Multiple diaphragm chambers 44 and 54 may also be provided as separate, independent structures. In the liquid-liquid extraction apparatus of the present invention, since the diaphragm chambers serving as pulsators are installed outside the extraction columns 10 and 20, maintenance is simplified. Furthermore, since there are no operating components such as Karr columns or RDCs within the extraction columns, any problems can be easily addressed.

[0043] In a further preferred embodiment of the liquid-liquid extraction apparatus of the present invention, as shown in Figures 1 and 2 , the diaphragm chambers 44 and 54 are desirably configured such that the check valves (not shown) at the inlets 61A and 61B and outlets 62A and 62B of a diaphragm pump 60, which is electrically or pneumatically driven, are removed. The outlet 61A of one chamber 44 and the inlet 62B of the other chamber 54 are sealed with partitions 64A and 64B. Each chamber has only one liquid flow path, and each chamber 61A and 61B utilizes an improved diaphragm pump equipped with degassing nozzles 66A and 66B. The pipes 42 and 52 of the two extraction columns are connected to the diaphragm pumps, respectively. This configuration allows pulsation to be applied to multiple extraction columns by operating a single diaphragm pump, thereby reducing the equipment volume and achieving an economical apparatus structure. Furthermore, the desired structure can be obtained by simply modifying an existing diaphragm pump, thereby making it easy to manufacture the device.

[0044] The improved diaphragm pump 60, which is a pulsator connected to two towers and is used in a more preferred embodiment of the liquid-liquid extraction apparatus of the present invention, does not mix the liquids between the two diaphragm chambers 44 and 54 therein. Therefore, one or more towers can be used to perform forward extraction for component separation and back extraction for separating the extracted substance from the extractant.

[0045] In one embodiment shown in FIG1 , a diaphragm pump 60 having undergone the aforementioned predetermined modification is connected to the two extraction columns 10 and 20 via their respective pipes 42 and 52 in proportion. Furthermore, in the liquid-liquid extraction apparatus of the present invention, in an embodiment in which the number of extraction columns (n) disposed within the apparatus is three or more, when a diaphragm chamber is configured to apply pulsation to each extraction column using the diaphragm pump 60 having undergone the aforementioned predetermined modification, the configuration can be similar to the configuration of the embodiment shown in FIG1 , whereby a diaphragm pump 60 having undergone the predetermined modification is connected to the two extraction columns via their respective pipes in proportion. Alternatively, a configuration can be employed in which one diaphragm pump 60 is used for each of the two extraction columns, or one or both of the two pipes 42 and 52 connected to the one diaphragm pump 60 are branched in the middle, thereby connecting three or more extraction columns to apply pulsation to each extraction column using one diaphragm pump. Furthermore, when each pipe 42, 52 is branched to connect to a plurality of extraction towers, in order to apply independent pulsation to each of the plurality of extraction towers, the extraction towers can be replaced with an extraction tower having the following structure: an opening and closing means such as an opening and closing valve is provided on each of the branches, and the pulsation from any chamber portion 44, 54 of the diaphragm pump 60 is transmitted by the opening and closing operation.

[0046] By branching one or both of the two pipes 42, 52 connected to the diaphragm pump 60 in the middle, in an embodiment in which a diaphragm pump is connected to more than three extraction towers, the pressure regulating chambers 46, 56 arranged in the middle of the pipes as shown in Figure 1 can also be set in the middle of the branched pipes and correspond to each extraction tower, or a pressure regulating chamber can be set on the side of the branched pipe closer to the diaphragm pump to correspond to multiple extraction towers.

[0047] In the liquid-liquid extraction apparatus of the present invention, when an extraction column is used in various systems, multiple pipes and valves for applying pulsation to the extraction column are pre-branched from the diaphragm pump 60 serving as a pulsator. Depending on the system, the location where pulsation is applied can be arbitrarily selected by operating the valves, and the amplitude of each pulsation can be freely controlled.

[0048] In one embodiment of the liquid-liquid extraction apparatus of the present invention shown in FIG1 , the connection portions of the pipes 42 and 52 between the extraction columns 10 and 20 and their respective diaphragm chambers 44 and 54 are located at the bottom of the columns, for purposes of illustration. However, in the liquid-liquid extraction apparatus of the present invention, the location of the connection portions of the pipes 42 and 52 between the multiple extraction columns and their respective diaphragm chambers 44 and 54 is not particularly limited and can be installed at any location where pulsation is desired, and can be located at the same or different locations relative to the extraction columns.

[0049] In one embodiment of the liquid-liquid extraction apparatus of the present invention shown in FIG1 , the extraction towers 10 and 20 each have gas-liquid interfaces 19 and 29 at their tops and are connected by a pressure-equalizing pipe 70 at the tops of the towers, thereby maintaining uniform pressure within each tower. In FIG1 , reference numeral 72 indicates a vent provided on the pipe of the pressure-equalizing pipe 70. Thus, all or a portion of the multiple extraction towers in the liquid-liquid extraction apparatus of the present invention are connected by the pressure-equalizing pipe 70. By achieving uniform pressure within each connected tower, the multiple extraction towers with uniform pressure can replace a single tall tower, enabling the same extraction operation to be performed using these multiple, shorter extraction towers.

[0050] [Example]

[0051] Hereinafter, the present invention will be described in more detail based on examples. FIG1 is a schematic diagram showing the overall structure of the extraction device used in the embodiment, and FIG2 is a schematic diagram showing the structure of the diaphragm pump used in the embodiment.

[0052] In FIG1 , two extraction towers 10 and 20 are prepared, each having a diameter of 65 mm and a height of 6 m, with a 1 m free space at the top and bottom, and filled with 4 m of irregular packing 12 and 22 of corrosion-resistant metal having a specific surface area of ​​435 m 2 / m 3. The upper sides of the packings 12 and 22 are equipped with spray nozzles 14 and 24 for supplying heavy liquid and overflow nozzles 16 and 26 for discharging light liquid. The pressure indicators 18 and 28 for monitoring pressure on the lower sides of the packings and the check valve of the pneumatic liquid-feeding diaphragm pump driven by compressed air are removed. As shown in Figure 2, in the flow paths 44 and 54 within the pump, an air-driven diaphragm pump 60 is connected to the two towers via pipes 42 and 52. The air-driven diaphragm pump 60 has been improved by installing partitions 64A and 64B.

[0053] The heavy liquid consists of 20% formic acid as the extraction component, 15% inorganic salts as the other components, and the remainder as an aqueous medium. The light liquid is a mixture of tributyl phosphate (TBP) as the extractant and n-decane as the diluent, with a mass ratio of (TBP:decane) 3:1. The density of the heavy liquid is 1190 kg / m³, and the density of the light liquid is 900 kg / m³.

[0054] Since the heavy liquid is used as the dispersed phase, the heavy liquid is supplied to the towers 10 and 20 using spray nozzles 14 and 24 with a nozzle diameter of Φ1.5 mm and 10 holes.

[0055] Since the mixed liquid of the extractant and the dilution solvent serves as the light liquid (continuous phase), liquid supply nozzles 15 and 25 are set in the hollow part of the tower bottom, and are supplied from there and extracted from overflow nozzles 16 and 26 at the top of the tower as the continuous phase discharge port.

[0056] In order to use two towers for continuous countercurrent liquid-liquid extraction, heavy liquid as the dispersed phase is supplied from the first tower (left tower in the figure) 10, heavy liquid extracted from the bottom of the first tower is supplied as the dispersed phase to the second tower (right tower in the figure) 20, liquid discharged from the bottom of the second tower is supplied as treated heavy liquid, light liquid as the continuous phase is supplied from the bottom of the second tower, light liquid discharged from the overflow nozzle 26 of the second tower is temporarily received in the buffer tank 86, and this liquid is supplied to the bottom of the first tower, and liquid discharged from the overflow nozzle 16 of the first tower is used as treated light liquid.

[0057] Comparative Example 1: No pulsation First, perform the extraction process without operating the diaphragm pump. Pre-fill the column with the remaining portion. When the supply of light and heavy liquids reaches five times the column volume, steady-state measurement data is taken. In terms of mass ratio, the light liquid flow rate is twice the heavy liquid flow rate. As a result, the following composition was obtained.

[0058] [Table 1] Water composition Formic acid composition Salt composition Extraction agent +Diluent composition Processing capacity kg / h Light liquid before treatment 0 0 0 1.000 200 Heavy liquid before treatment 0.65 0.2 0.15 0 100 Treated light liquid 0.025 0.082 0 0.893 224 Heavy liquid after treatment 0.781 0.022 0.197 0 76

[0059] Under these conditions, the formic acid recovery rate of the heavy liquid was 91.8%.

[0060] Example 1: Only the second tower has pulsation First, while gas was removed from the diaphragm's degassing line, the column liquid was supplied to the diaphragm, filling the diaphragm pump 30 with liquid. Then, pulsation was applied only to the second column 20. The volume of the diaphragm pushed in was 80 ml, and the porosity of the filled portion was 98%. The liquid level moved approximately 5 cm per beat (amplitude). The frequency was set to 30 Hz, and the conditions were otherwise identical to those without pulsation. As a result, the following composition was obtained.

[0061] [Table 2] Water composition Formic acid composition Salt composition Extraction agent +Diluent composition Processing capacity kg / h Light liquid before treatment 0 0 0 1.000 200 Heavy liquid before treatment 0.65 0.2 0.15 0 100 Treated light liquid 0.025 0.089 0 0.886 225 Heavy liquid after treatment 0.792 0.008 0.2 0 75

[0062] Example 2: The first tower has pulsation, and the pulsation conditions are the same as those in Example 1 Pulsation was also applied to the first tower. The test was conducted under the same conditions as in Example 1. As a result, the heavy liquid had difficulty dripping to the bottom of the first tower, where the dispersed phase resided, resulting in a phenomenon called "flooding" within the tower. This phenomenon was detected by monitoring the pressure within the tower. Because the first tower had a heavy liquid supply port and a light liquid discharge port from the second tower, the amount of formic acid was greater than that of the first tower. Consequently, the flow rate of the treated liquid increased from the second tower, making it difficult for the heavy liquid in the dispersed phase to drip due to the pulsation, leading to flooding.

[0063] Example 3: There is pulsation in both towers, and the pulsation amplitude is reduced to half Using a damper, the pressure inside the damper was adjusted according to the amount of compressed air introduced, and the amplitude of the two towers was set to half (2.5 cm) under the conditions of Example 2. As a result, the following composition was obtained.

[0064] [Table 3] Water composition Formic acid composition Salt composition Extraction agent +Diluent composition Processing capacity kg / h Light liquid before treatment 0 0 0 1.000 200 Heavy liquid before treatment 0.65 0.2 0.15 0 100 Treated light liquid 0.025 0.088 0 0.887 226 Heavy liquid after treatment 0.797 0.001 0.202 0 74

[0065] The concentration of the treated heavy liquid was reduced to 0.001 by mass, and the formic acid recovery rate was 99.6%.

[0066] Although the present invention has been disclosed above by way of embodiments, they are not intended to limit the present invention. Those skilled in the art may make modifications and alterations without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention shall be determined by the scope of the appended patent applications.

[0067] 10, 20: Extraction tower 12, 22: Filling 14, 24: spray nozzle 15, 25: Nozzle 16, 26: Overflow nozzle 17, 27: Drain pipe 18, 28: Pressure indicator 19, 29: Gas-liquid interface 32, 42, 52: pipeline 44, 54: diaphragm cavity 46, 56: pressure regulating chamber 48, 58: On / Off valve 60:Diaphragm pump 61A, 61B: Inlet 62: Diaphragm 62A, 62B: Outflow 64A, 64B: partition 66A, 66B: Degassing nozzle 70: Pressure equalizing tube 72: Exhaust port 82: Heavy liquid tank 84: Light liquid tank 86: Light liquid buffer tank

Claims

1. A multi-tower liquid-liquid extraction device, comprising multiple extraction towers, characterized in that n (n being an integer greater than or equal to 2) extraction towers are arranged side-by-side, wherein: Each of the n extraction columns has a heavy liquid supply section at the top and a heavy liquid discharge section at the bottom, and each also has a light liquid supply section at the bottom and a light liquid discharge section at the top; (a) the heavy liquid discharge section of the first extraction column is connected to the heavy liquid supply section of the second extraction column via a pipe, the heavy liquid discharge section of the second extraction column is connected to the heavy liquid supply section of the third extraction column via a pipe, ... the heavy liquid discharge section of the (n-1)th extraction column is connected to the heavy liquid supply section of the nth extraction column via a pipe, thus connecting the heavy liquid flow paths of the n extraction columns in series; and / or, (b) The light liquid discharge section of the nth extraction column is connected to the light liquid supply section of the (n-1)th extraction column via a pipe, the light liquid discharge section of the (n-1)th extraction column is connected to the light liquid supply section of the (n-2)th extraction column via a pipe, ... the light liquid discharge section of the second extraction column is connected to the light liquid supply section of the first extraction column via a pipe, thus connecting the light liquid flow paths of the n extraction columns in series; furthermore, at least two of the n extraction columns are connected to their respective diaphragm chambers via their respective pipes, the diaphragm chambers having a closed space, a portion of which is formed by a diaphragm and whose volume is changed by an operating drive; each of the n extraction columns and its respective diaphragm chamber has a pressure regulating chamber and an on / off valve for adjusting the internal pressure.

2. The liquid-liquid extraction apparatus as claimed in claim 1, wherein the diaphragm chamber comprises a diaphragm pump driven by an electric motor or compressed air, wherein check valves are removed from the inlet and outlet of two chamber sections that are alternately operated by diaphragms having walls forming each chamber, and the outlet of one chamber section and the inlet of the other chamber section are sealed by a partition, each chamber section has only one liquid flow path, and each chamber section uses an improved diaphragm pump equipped with a degassing nozzle, wherein the pipes of the n extraction towers are respectively connected to the diaphragm pump.

3. The liquid-liquid extraction apparatus as described in claim 1 or 2, wherein the n extraction columns are two extraction columns.

4. The liquid-liquid extraction apparatus as described in claim 2, wherein, There are three or more extraction towers, and the three or more adjacent extraction towers are connected separately, or any two or more extraction towers are connected to the diaphragm pump via pipelines.

5. The liquid-liquid extraction apparatus as described in claim 1 or 2, wherein, The liquid amplitude caused by the pulsation of the extraction device can be adjusted by the pressure difference between the pressure at any position in the tower, which is obtained from the average density and liquid level of the liquid in each of the n extraction towers, and the pressure in the pressure regulating chamber.

6. The liquid-liquid extraction apparatus as described in claim 1 or 2, wherein the pulsation of the extraction apparatus can be achieved by adjusting the pressure in the pressure regulating chamber and opening and closing valves to pulsate only any one column.

7. The liquid-liquid extraction apparatus as described in claim 1 or 2, wherein the pulsation of the extraction apparatus can be adjusted by individually regulating the pressure within the pressure regulating chamber, thereby changing the amplitude according to each extraction column.

8. The liquid-liquid extraction apparatus as described in claim 1 or 2, wherein, Each of the n extraction columns has a gas-liquid interface at the top of the column and is connected by a pressure equalization pipe at the top of the column, so that the pressure inside the column is uniform.

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