TW202410948A - Liquid-liquid extraction device - Google Patents

Abstract

A liquid-liquid extraction device having a plurality of extraction towers is characterized in that n (n is an integer greater than 2) extraction towers are arranged side by side, and each extraction tower has a heavy-liquid supply part on a top side of the extraction tower and a heavy-liquid discharge part on a bottom side of the extraction tower, and a light-liquid supply part on the bottom side of the extraction tower and a light-liquid discharge part on the top side of the tower; the n extraction towers has heavy-liquid flow paths which are connected in series, and at least two of the n extraction towers are connected with their diaphragm chamber by their pipelines; the diaphragm chamber have the closed spaces, part of the walls thereof are formed by a diaphragm, and the volume thereof is changed by running a driving part; the pipelines between the each extraction tower and their diaphragm chamber are all equipped with a pressure regulating chamber and an on-off valve that can adjust the internal pressure.

Description

Liquid-Liquid Extraction Device

The present invention relates to a liquid-liquid extraction device, in particular to a liquid-liquid extraction device which has a relatively low height of an extraction tower, has fewer restrictions on the installation location, is relatively simple in structure and can efficiently perform extraction.

Liquid-liquid extraction is a process of extracting the desired substance by transferring the solute dissolved in the solvent to another solvent for separation and purification. This liquid-liquid extraction process has the following problems: from the perspective of substance transfer, its efficiency is lower than that of separation such as distillation, adsorption and absorption, and the contact efficiency and contact time between liquids are increased, so the height of the extraction tower used is high, which is limited in setting.

In addition, from the viewpoint of the above-mentioned substance transfer, a mixer-settler type extraction column has been developed which has improved efficiency and has an operating section such as a continuous extraction device MS column and an operating tray itself such as a Karr column.

Since these extraction devices have a running part inside the tower, the mechanism is complex and there are problems with maintenance and introduction cost. On the other hand, the packed tower of liquid-liquid extraction is a simple structure filled with fillers, which has advantages in terms of maintenance and introduction cost, but there is a problem of low liquid-liquid contact efficiency.

In addition, as disclosed in Patent Document 1 (Japanese Patent Laid-Open No. 5-192505), Patent Document 2 (Japanese Patent Laid-Open No. 5-337304) and Patent Document 3 (Japanese Patent Laid-Open No. 7-31803), pulsating towers are also widely known as solvent extraction devices mainly used for the circulation of atomic raw materials. Pulsating towers have the advantages of being able to operate continuously and having a shorter solvent retention time inside the pulsating tower, so that the radiation damage to the solvent is less. However, although the previous pulsating (flapping) packed tower has good performance, it has the problem of being prone to overflow and having a narrow operating range due to the overall pulsation inside the tower.

For example, Patent Document 4 (Japanese Patent Laid-Open No. 2018-15754) discloses the following structure: on the basis of applying pulsation to the treatment tower, a diaphragm pump installed outside the treatment tower is used, one of the discharge part or the suction part of the diaphragm pump is shielded, and the other is connected to the inside of the treatment tower, so that the internal fluid of the treatment tower reciprocates. A liquid-liquid extraction device is disclosed, which forms pulsation by using an external diaphragm pump, thereby reducing the cost of the equipment in a simple way compared to a conventional pulsating tower. However, even a liquid-liquid extraction device using such a diaphragm pump has the following unresolved problems: the contact efficiency and retention time between the liquids as described above are increased, the height of the extraction tower is increased, and the installation is restricted. Furthermore, the device disclosed in Patent Document 4 has the following problem: although it is explained that the capacity of the diaphragm pump is selected based on the value of the required pulse amplitude multiplied by the internal cross-sectional area of the pulsating tower, the diaphragm amplitude cannot be adjusted because there is no adjustment margin, and overflow is likely to occur depending on the extraction system.

Therefore, the subject of the present invention is to provide a liquid-liquid extraction device that solves the problems existing in the above-mentioned conventional technology. The subject of the present invention is also to provide a liquid-liquid extraction device that has a relatively low height of the extraction tower, has fewer restrictions on the installation location, is relatively simple in structure, and can efficiently perform extraction.

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

In one embodiment of the liquid-liquid extraction device of the present invention, the following embodiment is shown, wherein the diaphragm chamber is a diaphragm pump which is driven electrically or by compressed air and has two chamber sections which are alternately operated by diaphragms forming the walls of each chamber, and the check valves of the inlets and outlets are removed, and the outlet of one chamber section and the inlet of another chamber section are closed 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, so that the pipelines of the two extraction towers are respectively connected to the diaphragm pump.

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.

In one embodiment of the liquid-liquid extraction device of the present invention, the following aspect is shown, in which the amplitude of the extraction device can be adjusted by the pressure difference between the pressure at any position in the tower obtained from the average density of the liquid in each extraction tower and the liquid level and the pressure in the pressure regulating chamber.

In one embodiment of the liquid-liquid extraction device of the present invention, the following aspect is shown, wherein the pulsation of the extraction device can be performed by adjusting the pressure in the pressure regulating chamber and opening and closing the valve to allow only one tower to pulsate.

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.

In one embodiment of the liquid-liquid extraction device of the present invention, the following aspect 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.

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

[Invention Effect]

The liquid-liquid extraction device of the present invention is a multi-tower liquid-liquid extraction device having multiple extraction towers. Since the multiple extraction towers are arranged side by side, even if the contact efficiency and retention time between liquids need to be increased, the height is lower than that of a single-tower extraction tower, so it is easier to install in existing equipment. In addition, in the liquid-liquid extraction device of the present invention, the pulsator is not a pulsator with a complex mechanism, and can be improved by using the existing diaphragm pump, so it is also more economical.

Furthermore, in the liquid-liquid extraction device of the present invention, the connection part of the pipeline between the multiple extraction towers and the respective diaphragm chambers can be installed at any place where pulsation is desired, and the pulsation amplitude and frequency can be adjusted arbitrarily, and pulsation can be applied to only one tower. Therefore, for example, as long as the concentration gradient of the first tower is large and biomass transfer is prone to occur, pulsation can be applied to the second tower instead of the first tower, so as to perform effective extraction and save the power of the pulsator.

Furthermore, in the liquid-liquid extraction device 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, in the liquid-liquid extraction device of the present invention, by introducing a diaphragm chamber as a pulsator from the outside of the extraction tower, it can also be applied to the modification of an existing extraction tower.

Furthermore, 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 the overflow phenomenon in which 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 the excessive transfer of droplets, the amplitude increase frequency can be adjusted to be faster, so the range of applicable systems is wider.

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 tower is large, the liquid flow rate of the first tower is larger than that of the second tower. Therefore, from the perspective of preventing overflow, the amplitudes of the first tower and the second tower can be changed or only the amplitude of the first tower can be stopped.

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

Furthermore, when an extraction tower is used in various systems, multiple pipes and valves for applying pulsation to the extraction tower can be branched from the pulsator. Depending on the system, the position to apply pulsation can be arbitrarily selected by valve operation, and the amplitude of each pulsation can be freely controlled.

Furthermore, since the pulsator connected to the two towers does not mix the liquid in the pulsator, 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.

In order to make the above and other purposes, features and advantages of the present invention more clearly understood, the following is a detailed description of the embodiments with reference to the accompanying drawings.

The present invention is described in more detail below according to the implementation forms.

FIG1 is a schematic diagram of the overall structure of an embodiment of the 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 the liquid-liquid extraction device of the present invention.

The liquid-liquid extraction device of the present invention is a multi-tower liquid-liquid extraction device having a plurality of extraction towers, wherein n (n is an integer greater than or equal to 2) extraction towers are arranged side by side. In the embodiment shown in FIG1 , an example of a configuration in which two extraction towers (n=2) of the minimum structure in the multi-tower liquid-liquid extraction device 1 of the present invention are arranged side by side is shown, but in the liquid-liquid extraction device 1 of the present invention, the number of extraction towers (n) can of course also be greater than 3. Moreover, although there is no particular limitation, the number n is usually, for example, 2 to 4, and more preferably about 2 to 3. Thus, since a plurality of extraction towers are arranged side by side, even if it is necessary to increase the contact efficiency and retention time between liquids, the height is lower than that of a single-tower extraction tower, making it easier to install in existing equipment, etc. In this specification, the term "arranged side by side" means that, in a certain installation location, the extraction towers are arranged side by side relative to the installation surface. This has a broad meaning and does not mean that their positions, intervals, angles, etc. are completely consistent. In addition, the "installation surface" is usually composed of a horizontal plane, but it can also be a state with steps on the surface, a state with curvature on the surface, or even a state where the installation surface can be divided into multiple layers.

Therefore, since multiple extraction towers are arranged side by side, even if the contact efficiency and retention time between 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.

In the liquid-liquid extraction device of the present invention, each extraction tower has a heavy liquid supply part on the tower top side and a heavy liquid discharge part on the tower bottom side, and also has a light liquid supply part on the tower bottom side and a light liquid discharge part on the tower top side. In the embodiment shown in FIG. 1 , in each extraction tower 10, 20, a shower nozzle 14, 24 as a heavy liquid supply part and an overflow nozzle 16, 26 as a light liquid discharge part are provided on the upper side (tower top side) of the packing 12, 22 arranged in the tower, and a nozzle 15, 25 as a light liquid supply part and a drain pipe 17, 27 as a heavy liquid discharge part are provided in the hollow part at the bottom of the tower on the lower side of the packing (tower bottom side). As long as it can effectively function as an extraction tower, there is no particular limitation on the shape of each supply part and each discharge part and the strict arrangement position.

In the liquid-liquid extraction device of the present invention, in order to play the role of multi-tower type, it is necessary to meet the following requirements: (a) the heavy liquid discharge part of the first extraction tower among the n extraction towers is connected to the heavy liquid supply part of the second extraction tower through a pipeline, the heavy liquid discharge part of the second extraction tower is connected to the heavy liquid supply part of the third extraction tower through a pipeline, ... the heavy liquid discharge part of the (n-1)th extraction tower is connected to the heavy liquid supply part of the nth extraction tower through a pipeline, in this way, the heavy liquid flow paths of the n extraction towers are connected in series; and/or, (b) The light liquid discharge section of the nth extraction tower among the n extraction towers is connected to the light liquid supply section of the (n-1)th extraction tower via a pipeline, the light liquid discharge section of the (n-1)th extraction tower is connected to the light liquid supply section of the (n-2)th extraction tower via a pipeline, ... the light liquid discharge section of the second extraction tower is connected to the light liquid supply section 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.

In the embodiment shown in FIG. 1 , this point is explained, (a) the heavy liquid discharge part (drain pipe) 17 of the first extraction tower 10 of the two extraction towers 10 and 20 is connected to the heavy liquid supply part (sprinkler nozzle) 24 of the second extraction tower via the pipeline 32, in this way the heavy liquid flow paths of the two extraction towers are connected in series, and, (b) the light liquid discharge part (overflow nozzle) 26 of the second extraction tower 20 of the two extraction towers 10 and 20 is connected to the light liquid supply part (nozzle) 15 of the first extraction tower 10 via the pipeline 34, in this way the light liquid flow paths of the two extraction towers are connected in series.

In the embodiment shown in FIG. 1 , 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.

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.

Furthermore, in the liquid-liquid extraction apparatus of the present invention, in an aspect 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, relative to the total number (N) of extraction towers of the entire liquid-liquid extraction apparatus, the number (n) of extraction towers in the conditions (a) and (b) is set to a value smaller than the total number (N) to satisfy the series connection structure of the heavy liquid flow path and/or the light liquid flow path.

Furthermore, in the liquid-liquid extraction device of the present invention, at least two of the n extraction towers 10, 20 are connected to respective diaphragm chambers 44, 54 through respective pipes 42, 52, and the diaphragm chambers have closed spaces, part of the walls of which are formed by diaphragms and whose volumes are changed by operating the driving part. The pipes 42, 52 between each extraction tower 10, 20 and the respective diaphragm chambers 44, 54 are provided with pressure regulating chambers 46, 56 and on-off valves 48, 58 for adjusting the internal pressure during the period.

Therefore, in one embodiment of the liquid-liquid extraction device of the present invention, the pulsation of the extraction device can adjust the pressure in the pressure regulating chambers 46, 56 and the opening and closing valves 48, 58 to make only one tower pulsate, and by adjusting the pressure in the pressure regulating chambers 46, 56 respectively, the pulsation can be applied to each extraction tower 10, 20 separately.

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 the overflow phenomenon in which 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 the excessive transfer of droplets, the amplitude increase frequency can be adjusted faster, so the range of applicable systems is wider.

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 tower 10 is large, the liquid flow rate of the first tower is larger than that of the second tower 20. Therefore, from the perspective of preventing overflow, the amplitudes of the first tower and the second tower can be changed or only the amplitude of the first tower can be stopped.

Furthermore, in the embodiment shown in FIG. 1 , since there are only two extraction towers 10 and 20 arranged side by side in the liquid-liquid extraction device, the two extraction towers 10 and 20 are connected to the diaphragm chambers 44 and 54 through pipes 42 and 52. However, in the embodiment in which the number of extraction towers n in the liquid-liquid extraction device of the present invention is 3 or more, it is not necessary to connect all the extraction towers to the diaphragm chamber, and at least two of the three or more extraction towers may be connected to the diaphragm chamber. That is, in another embodiment of the liquid-liquid extraction device of the present invention, among the extraction towers, the n extraction towers are three or more extraction towers, the adjacent extraction towers are three or more towers, or any two or more towers are connected to the above-mentioned improved diaphragm pump through pipes. This is because, in the liquid-liquid extraction device of the present invention, as long as the structure is capable of applying pulsation to the diaphragm chambers of at least two or more extraction towers among a plurality of extraction towers arranged side by side, the expected effect can be exerted.

In the liquid-liquid extraction apparatus of the present invention, the diaphragm chambers 44 and 54 for applying pulsation to the extraction towers 10 and 20 are not particularly limited as long as they have a closed space whose wall surface is partially formed by the diaphragm and whose volume is changed by the operating drive unit as described above, and can apply pulsation to the extraction towers 10 and 20. A plurality of diaphragm chambers 44 and 54 may be provided as separate independent structures. In the liquid-liquid extraction apparatus of the present invention, since the diaphragm chambers as pulsators are installed outside the extraction towers 10 and 20, maintenance is easy, and since there is no operating unit such as a Karr column or RDC inside the extraction tower, it is easy to deal with problems when they occur.

Furthermore, in a more preferred embodiment of the liquid-liquid extraction device of the present invention, as shown in FIGS. 1 and 2 , it is expected that the diaphragm chambers 44, 54 are constructed by removing the check valves (not shown) of the inlets 61A, 61B and the outlets 62A, 62B of the diaphragm pump 60, which is electrically or compressed air-driven and alternately operated by two chamber sections having a diaphragm 62 forming the wall of each chamber, and the outlets 61A, 61B of one chamber section 44 and the inlet 62B of the other chamber section 54 are closed by partitions 64A, 64B, each chamber section has only one liquid flow path, and each chamber section 61A, 61B uses an improved diaphragm pump equipped with a degassing nozzle 66A, 66B, so that the pipes 42, 52 of the two extraction towers are respectively connected to the diaphragm pump. By adopting this structure, multiple extraction columns can be pulsed by operating one diaphragm pump, so the equipment volume can be reduced and an economical device structure can be realized. In addition, the required structure can be obtained by simply modifying the existing diaphragm pump, so that the device can be easily manufactured.

The improved diaphragm pump 60 as a pulsator connected to two towers used in a more preferred embodiment of the liquid-liquid extraction device of the present invention does not mix the liquid between the two diaphragm chambers 44 and 54 therein, so 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.

In one embodiment shown in FIG. 1 , the following aspect is shown: for two extraction towers 10 and 20, a diaphragm pump 60 having undergone the above-mentioned predetermined modification is connected in proportion through respective pipes 42 and 52. Furthermore, in the liquid-liquid extraction apparatus of the present invention, in an embodiment in which the number (n) of extraction towers arranged in the apparatus is 3 or more, when a diaphragm chamber is constructed in which a diaphragm pump 60 that has undergone the above-mentioned predetermined modification is used to apply pulsation to each extraction tower, the structure is the same as the embodiment shown in FIG. 1 , and for two extraction towers, one diaphragm pump 60 that has undergone the predetermined modification is connected to each other through the respective pipelines in proportion, that is, one diaphragm pump 60 is used for each of the two extraction towers, or one or both of the two pipelines 42, 52 connected to one diaphragm pump 60 are branched in the middle, so that for three or more extraction towers, one diaphragm pump is connected to each extraction tower to apply pulsation. Furthermore, when each pipe 42, 52 is branched to connect to a plurality of extraction towers, in order to be able to apply independent pulses to the plurality of extraction towers, the extraction towers can be replaced with extraction towers having the following structure: an opening and closing means such as an on-off valve is provided on each of the branches, and the pulse from any chamber part 44, 54 of the diaphragm pump 60 is transmitted by the opening and closing operation.

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 FIG. 1 can also be arranged in the middle of the branched pipes and correspond to each extraction tower, or a pressure regulating chamber can be arranged on the side closer to the diaphragm pump than the branched pipes to correspond to multiple extraction towers.

In the liquid-liquid extraction device of the present invention, when an extraction tower is used in various systems, a plurality of pipes and valves for applying pulsation to the extraction tower are pre-branched from the diaphragm pump 60 as a pulsator. Depending on the system, the position to apply pulsation can be arbitrarily selected by valve operation, and the respective pulsation amplitudes can be freely controlled.

In one embodiment of the liquid-liquid extraction device of the present invention shown in FIG1 , the connection parts of the pipes 42, 52 between the extraction towers 10, 20 and the respective diaphragm chambers 44, 54 are all arranged on the bottom side of the tower, which is an example. However, in the liquid-liquid extraction device of the present invention, the position of the connection parts of the pipes 42, 52 between the plurality of extraction towers and the respective diaphragm chambers 44, 54 is not particularly limited, and can be installed at any place where pulsation is desired, and can also be located at the same position or different positions relative to each extraction tower.

Furthermore, in an embodiment of the liquid-liquid extraction device of the present invention shown in FIG1 , the extraction towers 10 and 20 have gas-liquid interfaces 19 and 29 at the top of the towers, and are respectively connected by a pressure equalizing pipe 70 at the top of the towers, so that the pressure in each tower is uniform. Furthermore, in FIG1 , symbol 72 represents an exhaust port provided on the pipe of the pressure equalizing pipe 70. Thus, all or part of the multiple extraction towers in the liquid-liquid extraction device of the present invention are respectively connected by the pressure equalizing pipe 70, and by making the pressure in each connected tower uniform, the multiple extraction towers with uniform pressure replace a higher single-tower extraction tower, and the same extraction operation can be performed by such multiple extraction towers with lower heights.

[Example]

The present invention is described in more detail below based on the embodiments. FIG. 1 is a schematic diagram showing the overall structure of the extraction device used in the embodiment, and FIG. 2 is a schematic diagram showing the structure of the diaphragm pump used in the embodiment.

In FIG1 , two extraction towers 10 and 20 are prepared, each having a diameter of 65 mm and a height of 6 m, and filled with 4 m of corrosion-resistant metal random packing 12 and 22 with a specific surface area of 435 m ² /m ³ in a state where a 1 m upper and lower free space is left. The upper side of the fillers 12, 22 is provided with shower nozzles 14, 24 for supplying heavy liquid and overflow nozzles 16, 26 for discharging light liquid. The pressure indicators 18, 28 for monitoring the pressure on the lower side of the fillers and the check valve of the pneumatic liquid delivery diaphragm pump using compressed air as the driving source are removed. As shown in FIG. 2, in the flow paths 44, 54 in the pump, the air-driven diaphragm pump 60 is connected to the two towers through pipes 42, 52, and the above-mentioned air-driven diaphragm pump 60 is improved by installing partitions 64A, 64B.

20% formic acid is used as the extraction component, 15% inorganic salt is dissolved as other components, and the rest is aqueous medium, which is used as the heavy liquid; tributyl phosphate (TBP) is used as the extractant, N-decane is used as the diluent of the extractant, and the mixed medium is used as the light liquid with a mass ratio (TBP: decane =) 3:1. The density of the heavy liquid is 1190kg/ ^m3 , and the density of the light liquid is 900kg/ ^m3 .

Since the heavy liquid is used as the dispersed phase, the heavy liquid is supplied to each tower 10 , 20 using a shower nozzle 14 , 24 having a nozzle hole diameter of Φ1.5 mm and 10 holes.

Since the mixed liquid of the extractant and the diluent solvent serves as the light liquid (continuous phase), liquid supply nozzles 15 and 25 are provided in the hollow portion at the bottom of the tower, and liquid is supplied therefrom and drawn out from overflow nozzles 16 and 26 at the top of the tower serving as the continuous phase discharge port.

In order to use two towers for continuous countercurrent liquid-liquid extraction, heavy liquid as 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 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 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 the liquid is supplied to the bottom of the first tower, and liquid discharged from the overflow nozzle 16 of the first tower is supplied as treated light liquid.

Comparison Example 1: No Pulsation First, the extraction process is performed without running the diaphragm pump. The retention portion is loaded into the tower in advance, and when the supply amount of light liquid and heavy liquid reaches 5 times the volume in the tower, it is used as the stable state measurement data. In terms of mass ratio, the light liquid flow rate is twice the heavy liquid flow rate. As a result, the following composition is obtained.

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

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

Example 1: Only the second tower has pulsation First, while removing gas from the degassing line of the diaphragm, the liquid in the tower is supplied to the diaphragm so that the diaphragm pump 30 is filled with liquid. Then, only the second tower 20 is pulsed. The volume of the diaphragm pushed in is 80ml, and the porosity of the filled part is 98%. The liquid level moves about 5cm per beat (amplitude). The frequency is set to 30Hz, and the conditions are the same as those without pulsation. As a result, the following composition is obtained.

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

Example 2: The first tower has pulsation, and the pulsation conditions are the same as those of Example 1 Pulsation is also applied to the first tower. In addition, the test is carried out under the same conditions as Example 1. As a result, the heavy liquid is difficult to drip to the bottom of the first tower, which is the dispersed phase, and a phenomenon of retention in the tower (overflow) occurs. This phenomenon is detected from the pressure in the tower. Since the first tower has a heavy liquid phase supply port and a light liquid phase discharge port from the second tower, the amount of formic acid is greater than that of the first tower. As a result, the flow rate of the liquid to be treated increases from the second tower, and the heavy liquid of the dispersed phase is difficult to drip due to the pulsation, so overflow occurs.

Example 3: Both towers pulsate, and the pulsation amplitude is halved Using a damper, the pressure in the damper is adjusted according to the amount of compressed air introduced, and the amplitude of the conditions of Example 2 is set to half of the two towers (2.5cm) and operated. As a result, the following composition is obtained.

[table 3] Water composition Formic acid composition Salt composition Extraction agent + diluent composition Processing capacity kg/h Pre-treatment light liquid 0 0 0 1.000 200 Heavy liquid before treatment 0.65 0.2 0.15 0 100 After treatment light liquid 0.025 0.088 0 0.887 226 Heavy liquid after treatment 0.797 0.001 0.202 0 74

The concentration of the treated heavy liquid was reduced to 0.001 by mass fraction. The formic acid recovery rate was 99.6%.

Although the present invention has been disclosed as above by way of embodiments, they are not intended to limit the present invention. A person having ordinary knowledge in the technical field to which the present invention belongs may make some changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the scope defined in the attached patent application.

10, 20: Extraction tower 12, 22: Filler 14, 24: Shower 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 cavity 48, 58: Open-close valve 60: Diaphragm pump 61A, 61B: Inlet 62: Diaphragm 62A, 62B: Outlet 64A, 64B: Partition 66A, 66B: Degassing nozzle 70: Pressure equalizing pipe 72: Exhaust port 82: Heavy liquid tank 84: Light liquid tank 86: Light liquid buffer tank

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

Claims (8)

A multi-tower liquid-liquid extraction device having a plurality of extraction towers, characterized in that: n (n is an integer greater than 2) extraction towers are arranged side by side, wherein: each extraction tower has a heavy liquid supply part on the tower top side and a heavy liquid discharge part on the tower bottom side, and also has a light liquid supply part on the tower bottom side and a light liquid discharge part on the tower top side; (a) the heavy liquid discharge part of the first extraction tower among the n extraction towers is connected to the heavy liquid supply part of the second extraction tower via a pipeline, the heavy liquid discharge part of the second extraction tower is connected to the heavy liquid supply part of the third extraction tower via a pipeline, ... the heavy liquid discharge part of the (n-1)th extraction tower is connected to the heavy liquid supply part of the nth extraction tower via a pipeline, and in this way the heavy liquid flow paths of the n extraction towers are connected in series; and/or (b) The light liquid discharge part of the nth extraction tower among the n extraction towers is connected to the light liquid supply part of the (n-1)th extraction tower through a pipeline, the light liquid discharge part of the (n-1)th extraction tower is connected to the light liquid supply part of the (n-2)th extraction tower through a pipeline, ... the light liquid discharge part of the second extraction tower is connected to the light liquid supply part of the first extraction tower through 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 through their respective pipelines, and the diaphragm cavity has 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 has a pressure regulating chamber and an on-off valve that can adjust the internal pressure. In the liquid-liquid extraction device as claimed in claim 1, the diaphragm chamber is a diaphragm pump which has two chamber parts which are alternately operated by diaphragms forming the walls of each chamber and is driven electrically or by compressed air, and the check valves of the inlet and outlet are removed, and the outlet of one chamber part and the inlet of the other chamber part are closed by a partition, each chamber part has only one liquid flow path and each chamber part uses an improved diaphragm pump equipped with a degassing nozzle, so that the pipelines of the two extraction towers are respectively connected to the diaphragm pump. In the liquid-liquid extraction device of claim 1 or 2, the n extraction towers are two extraction towers. A liquid-liquid extraction device as described in claim 2, wherein among the extraction towers, the n extraction towers are more than three extraction towers, the adjacent extraction towers are more than three towers connected separately, or any two or more towers are connected to the above-mentioned improved diaphragm pump through pipelines. A liquid-liquid extraction device as described in claim 1 or 2, wherein the amplitude of liquid caused by the pulsation of the extraction device can be adjusted by the pressure difference at any position in the tower obtained from the average density of the liquid in each extraction tower and the liquid level and the pressure in the pressure regulating chamber. In the liquid-liquid extraction device as described in claim 1 or 2, the pulsation of the extraction device can be carried out by adjusting the pressure in the pressure regulating chamber and opening and closing the valve to make only any one tower pulsate. In the liquid-liquid extraction device as described in claim 1 or 2, the pulsation of the extraction device can change the amplitude according to each extraction tower by individually adjusting the pressure in the pressure regulating chamber. A liquid-liquid extraction device as described in claim 1 or 2, wherein each extraction tower has a gas-liquid interface at the top of the tower and is connected to each other via a pressure equalizing pipe at the top of the tower so that the pressure inside the tower is uniform.