A composite extraction tower and its application

Abstract

The present application provides a composite extraction tower and its application. The tower body of the composite extraction tower of the present application is composed of a tower top, an extraction section and a tower bottom from top to bottom; a heavy phase liquid inlet pipe and a light phase liquid outlet pipe are respectively provided at the tower top, and a heavy phase liquid outlet pipe and a light phase liquid inlet pipe are respectively provided at the tower bottom; at least one group of mass transfer components are sequentially provided in the extraction section from top to bottom, and each group of mass transfer components sequentially includes a liquid gathering area and a liquid separation area from top to bottom, and a plurality of baffles are provided in the liquid gathering area, and all the baffles are sequentially distributed along the height direction of the tower body, and the liquid separation area is filled with packing rings for liquid separation. The composite extraction tower of the present application has a high separation efficiency and can improve the extraction yield.

Description

Technical Field

[0001] The present application relates to the field of extraction equipment, and in particular, to a composite extraction tower and its application. Background Art

[0002] The extraction tower (also known as the extraction tower) is a differential countercurrent mass transfer device. Its working principle is based on the mass transfer between liquids and liquids. Through the physical or chemical forces between the solvent and the target component (such as affinity, solubility and volatility, etc.), the target component is separated, enriched and purified. The extraction tower has multiple theoretical stages, small organic phase retention, high equipment volume efficiency, strong equipment sealing, etc. It is widely used in many fields such as petroleum, chemical industry, and medicine. However, the separation efficiency of the current extraction tower is not high, resulting in low extraction yield. Summary of the invention

[0003] The present application provides a composite extraction tower and application thereof. The composite extraction tower of the present application has high separation efficiency and can improve the extraction yield.

[0004] In the first aspect, the present application provides a composite extraction tower, which includes a tower body, which is composed of a tower top, an extraction section and a tower bottom from top to bottom; a heavy phase liquid inlet pipe and a light phase liquid outlet pipe are respectively provided at the tower top, and a heavy phase liquid outlet pipe and a light phase liquid inlet pipe are respectively provided at the tower bottom; at least one group of mass transfer components are sequentially arranged in the extraction section from top to bottom, and each group of mass transfer components sequentially includes a liquid gathering area and a liquid separation area from top to bottom, and a plurality of baffles are arranged in the liquid gathering area, and all the baffles are sequentially distributed along the height direction of the tower body, and the liquid separation area is filled with packing rings for liquid separation.

[0005] The inventors have found that the internal structure of the current extraction tower is relatively simple. Therefore, when the dispersed phase runs through the entire extraction tower, the droplets formed are uniform and fixed. The liquid surface cannot be updated in time after completing the mass transfer behavior, resulting in a decrease in the effective mass transfer specific surface area and a decrease in the mass transfer efficiency, which in turn leads to a low separation efficiency of the extraction tower and a low extraction yield.

[0006] In the above implementation process, when the composite extraction tower is working, different types of liquids (usually water and organic phase) with large differences in density and polarity are transported from the top and bottom of the tower to the inside of the tower body, and mass transfer is carried out in the mass transfer parts of the extraction section of the tower body. During the mass transfer process, since baffles are provided in the liquid gathering area, different types of liquids will aggregate and flow in the liquid gathering area to fully carry out mass transfer; when the liquids converge and flow downward to the liquid separation area, the packing rings in the liquid separation area cause the converged liquids to be redispersed into liquids, so that the liquid surface can be updated in time after the mass transfer behavior is completed, thereby increasing the surface area of ​​the effective mass transfer ratio, thereby improving the separation efficiency and extraction yield of the composite extraction tower. After the extraction is completed, liquids of different densities are discharged from the bottom and top of the tower respectively.

[0007] In one possible implementation, the baffle includes a first baffle and a second baffle, and the first baffle and the second baffle are alternately distributed in the liquid collection area along the height direction of the tower body, the edge of the first baffle is in contact with the inner wall of the tower body, and a liquid leakage port is provided on the first baffle; the projection area of ​​the second baffle on the first baffle covers the liquid leakage port and is smaller than the area of ​​the first baffle.

[0008] In the above implementation process, since the edge of the first baffle is in contact with the inner wall of the tower body, the liquid can only flow downward to the second baffle through the leakage port of the first baffle, and the projection area of ​​the second baffle covers the leakage port. Therefore, the liquid passing through the leakage port is basically received by the second baffle, and since the projection area of ​​the second baffle on the first baffle is smaller than the area of ​​the first baffle, the edge of the second baffle does not contact the inner wall of the tower body. Therefore, the liquid can continue to flow downward through the gap between the second baffle and the interior of the tower body, which can increase the flow distance of the liquid and allow better mass transfer between different types of liquids.

[0009] In a possible implementation, the spacing between adjacent baffles is 5 mm to 30 mm.

[0010] In the above implementation process, controlling the spacing between adjacent baffles within the range of 5 mm to 30 mm is beneficial to sufficient mass transfer between different types of liquids.

[0011] In a possible implementation, along the height direction of the tower body, in each mass transfer element, the ratio of the length of the liquid collecting zone to the length of the liquid separating zone is 5:1 to 1:5.

[0012] In a possible implementation, the diameter of the tower top is greater than the diameter of the extraction section; and / or the diameter of the tower bottom is greater than the diameter of the extraction section.

[0013] In the above implementation process, in the composite extraction tower that meets the above conditions, liquids of different densities can be discharged from the inside of the tower more quickly after mass transfer is completed.

[0014] In a possible implementation, the lowest point of the tower body is taken as the horizontal plane, the height of the heavy phase liquid inlet pipe from the horizontal plane is less than the height of the light phase liquid outlet pipe from the horizontal plane, and the height of the heavy phase liquid outlet pipe from the horizontal plane is less than the height of the light phase liquid inlet pipe.

[0015] In the above implementation process, after the extraction of liquids of different densities in the composite extraction tower is completed, sufficient space and time are left at the top and bottom of the tower to complete the stratification of the heavy phase and light phase mixed liquid, thereby ensuring the purity of the heavy phase outlet and the light phase outlet.

[0016] In a possible implementation, a support frame for supporting the packing ring is further provided inside the tower body, the support frame includes a bearing surface, the packing ring is located on the bearing surface, and the bearing surface is provided with a through hole, the diameter of the through hole is not greater than 4 mm, and the porosity of the bearing surface is 95%~98%.

[0017] In the above implementation process, the support frame can play a role in fixing the packing ring, ensuring that the packing ring can play a role in separating the liquid.

[0018] In a possible implementation, the packing ring includes at least one of a ball ring, a Raschig ring or a Theta ring; and / or the inner diameter of the packing ring is 4 mm to 25 mm.

[0019] In a possible implementation, a pulse pipe is further provided at the bottom of the tower.

[0020] In the above implementation process, the pulse pipe at the bottom of the tower can be connected to the pulse generator, which can improve the separation efficiency and extraction yield of the composite extraction tower.

[0021] In a second aspect, the present application provides the application of a composite extraction tower in a chemical separation process.

[0022] In the above implementation process, when the above composite extraction tower is used for chemical separation, the separation efficiency can be improved and the extraction yield can be increased. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments of the present application will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0024] Figure 1 A schematic diagram of the structure of a composite extraction tower provided in an embodiment of the present application;

[0025] Figure 2 This is a schematic diagram of the structure of the baffle plate in the liquid collecting area of ​​an embodiment of the present application.

[0026] Icon: 001-compound extraction tower; 100-tower top; 110-heavy phase liquid inlet pipe; 120-light phase liquid outlet pipe; 200-extraction section; 210-mass transfer component; 220-liquid gathering area; 221-baffle; 222-first baffle; 223-leakage port; 224-second baffle; 225-fixed rod; 230-liquid separation area; 231-packing ring; 300-tower bottom; 310-heavy phase liquid outlet pipe; 320-light phase liquid inlet pipe; 330-pulse pipeline. DETAILED DESCRIPTION

[0027] The technical solutions in the embodiments of the present application will be described below in conjunction with the drawings in the embodiments of the present application.

[0028] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. The components of the embodiments of the present application described and shown in the drawings here can be arranged and designed in various different configurations.

[0029] Therefore, the following detailed description of the embodiments of the present application provided in the accompanying drawings is not intended to limit the scope of the present application for which protection is sought, but merely represents selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present application.

[0030] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0031] In the description of the present application, it should be noted that the terms "upper", "lower", "inside", "outside", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, or are the orientations or positional relationships in which the product of the application is usually placed when in use. They are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0032] In the description of this application, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "disposed" and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0033] The inventors found that due to the relatively simple internal structure of the extraction tower in the prior art, the droplets formed when the dispersed phase runs through the entire extraction process are uniform and fixed, and the surface of the droplets cannot be updated in time after the mass transfer behavior is completed. Therefore, the effective mass transfer specific surface area of ​​the extraction tower is not high, and the mass transfer efficiency is low, which leads to the low separation efficiency of the current extraction tower and the low extraction yield. Although CN116747556A mentions a packed extraction tower prepared by different materials, its liquid update changes are small, so the improvement of separation efficiency is also relatively limited.

[0034] Based on the above content, the present application provides a composite extraction tower 001. When the composite extraction tower 001 of the present application is used in a chemical separation process, the separation efficiency can be significantly improved and the extraction yield can be increased.

[0035] Example

[0036] Please see Figure 1~Figure 2 The composite extraction tower 001 of the present application includes a tower body, which includes a tower top 100, an extraction section 200 and a tower bottom 300 from top to bottom. Liquids of different densities and polarities (usually water and an organic phase) are transmitted to the inside of the tower body through the tower top 100 and the tower bottom 300, and mass transfer is performed in the extraction section 200 inside the tower body. As an example, in the embodiment of the present application, the tower top 100, the extraction section 200 and the tower bottom 300 are usually connected by flanges (not shown in the figure), and then sealed with sealing materials to prevent the liquid in the tower body from leaking out of the tower body.

[0037] In the composite extraction tower 001 of the present application, the tower top 100 is respectively provided with a heavy phase liquid inlet pipe 110 and a light phase liquid outlet pipe 120, and the tower bottom 300 is respectively provided with a heavy phase liquid outlet pipe 310 and a light phase liquid inlet pipe 320. When the composite extraction tower 001 is working, the liquid with a higher density will enter the tower body through the heavy phase liquid inlet pipe 110 of the tower top 100, and the liquid with a lower density will enter the tower through the light phase liquid inlet pipe 320 of the tower bottom 300. Different types of liquids are countercurrently contacted in the extraction section 200 inside the tower body to fully carry out mass transfer exchange; after the mass transfer exchange is completed (i.e., the extraction process is completed), the liquid with a lower density will be discharged through the light phase liquid outlet pipe 120 of the tower top 100, and the liquid with a higher density will be discharged through the heavy phase liquid outlet pipe 310 of the tower bottom 300.

[0038] As an example, in the embodiments of the present application, in order to allow different types of liquids to be discharged more quickly from the inside of the tower body, the diameter of the tower top 100 is generally greater than the diameter of the extraction section 200, and the diameter of the tower bottom 300 is generally greater than the diameter of the extraction section 200. In addition, in some embodiments of the present application, in order to ensure that different types of liquids separated after extraction are not secondary polluted, with the lowest point of the tower body as the horizontal plane, the height of the heavy phase liquid inlet pipe 110 from the horizontal plane is less than the height of the light phase liquid outlet pipe 120 from the horizontal plane, and the height of the heavy phase liquid outlet pipe 310 from the horizontal plane is less than the height of the light phase liquid inlet pipe 320.

[0039] In addition, as an example, in the embodiments of the present application, a pulse pipe 330 is usually set at the bottom of the tower 300. The pulse generator can be connected to the interior of the tower body through the pulse pipe 330, and can ventilate the interior of the tower body with a pulse intensity of 3mm / s~15mm / s. This can enhance the degree of interface turbulence, accelerate the dispersion and mass transfer of substances, and help improve separation efficiency and extraction yield.

[0040] In the composite extraction tower 001 of the present application, the extraction section 200 is sequentially provided with at least one group of mass transfer elements 210 from top to bottom, and each group of mass transfer elements 210 sequentially includes a liquid collecting area 220 and a liquid separation area 230 from top to bottom, and a plurality of baffles 221 are provided in the liquid collecting area 220, and all the baffles 221 are sequentially distributed along the height direction of the tower body, and the liquid separation area 230 is filled with a packing ring 231 for liquid separation; different types of liquids can be mass transferred in the mass transfer elements 210 of the extraction section 200. In the present application, "a plurality of baffles 221" means that the number of baffles 221 is not less than two.

[0041] During the mass transfer process, since the baffle 221 is provided in the liquid gathering area 220, the liquid will aggregate and flow in the liquid gathering area 220 to fully carry out mass transfer; when the liquid converges and flows downward to the liquid separation area 230, the packing ring 231 in the liquid separation area 230 makes the converged liquid dispersed into liquid again, so that the liquid surface can be updated in time after the mass transfer behavior is completed, thereby increasing the surface area of ​​the effective mass transfer ratio, and then improving the separation efficiency and extraction yield of the compound extraction tower. At the beginning, as the number of mass transfer parts 210 increases, the frequency of droplet breakage and aggregation increases, the interface update is more uniform, and the extraction effect will be significantly improved; when the mass transfer parts 210 increase to a certain number, the time for a single droplet breakage and aggregation becomes shorter, so that the droplets cannot fully complete the breakage and aggregation process, resulting in a slow interface update and increased extraction difficulty. Therefore, in the actual production process, the number of mass transfer parts 210 is generally not more than 12, preferably 2 to 6. In addition, in the embodiment of the present application, along the height direction of the tower body, in each mass transfer member 210, the length ratio of the liquid collecting area 220 to the length ratio of the liquid separation area 230 is between 5:1 and 1:5, and different ratios are usually selected according to the actual use scenario, specifically 5:1, 4:1, 3:1, 2:1, 1:1, 1:2, 1:3, 1:4, 1:5 or within the range of any two of the above values. In addition, in the embodiment of the present application, the spacing between adjacent baffles 221 is usually controlled within the range of 5mm to 30mm, specifically 5mm, 8mm, 12mm, 18mm, 20mm, 25mm, 28mm, 30mm or within the range of any two of the above values, so that different types of liquids can be fully transferred.

[0042] As an example, the baffle 221 of the embodiment of the present application includes two different types of baffles, namely a first baffle 222 and a second baffle 224, and the first baffle 222 and the second baffle 224 are alternately distributed in the liquid collection area 220 along the height direction of the tower body, wherein the edge of the first baffle 222 is in contact with the inner wall of the tower body, and a liquid leakage port 223 is provided on the first baffle 222; the projection area of ​​the second baffle 224 on the first baffle 222 covers the liquid leakage port 223 and is smaller than the area of ​​the first baffle 222. The baffles 221 arranged in this way can enable sufficient mass transfer between liquids, because: since the edge of the first baffle 222 is in contact with the inner wall of the tower body, the liquid can only flow downward to the second baffle 224 through the leakage port 223 of the first baffle 222, and the projection area of ​​the second baffle 224 covers the leakage port 223, so the liquid passing through the leakage port 223 is basically received by the second baffle 224, and since the projection area of ​​the second baffle 224 on the first baffle 222 is smaller than the area of ​​the first baffle 222, the edge of the second baffle 224 is not in contact with the inner wall of the tower body, so the liquid can continue to flow downward through the gap between the second baffle 224 and the inside of the tower body, so that the flow distance of the liquid can be increased, so that different types of liquids can have better mass transfer. Of course, in some other embodiments, other types of baffles such as single-bow baffles and double-bow baffles can also be used, which will not be repeated in this application.

[0043] It should be noted that the present application does not have any special restrictions on the shapes of the first baffle 222 and the second baffle 224. However, since the interior of the tower body is usually cylindrical, the first baffle 222 is usually set to a circular shape, so that the edge of the first baffle 222 and the interior of the tower body can fit more closely. In order to unify the specifications, the second baffle 224 is usually also set to a circular shape. In addition, since the second baffle 224 will not contact the inner wall of the tower body, a fixing rod 225 is usually set to fix the second baffle 224, such as Figure 2 As shown, the fixing rod 225 penetrates the first baffle 222 and the second baffle 224. Moreover, in the present application, the first baffle 222 and the second baffle 224 are not necessarily parallel to each other, and there may be a certain angle between the planes where the two are located. In the specific embodiment of the present application, in order to facilitate the description of the technical solution, the adjacent first baffle 222 and the second baffle 224 are arranged to be parallel to each other.

[0044] In addition, the material of the baffle 221 of the present application is not particularly limited; as an example, in the embodiment of the present application, in order to improve the corrosion resistance and lipophilicity, the baffle 221 made of polytetrafluoroethylene is used.

[0045] In some embodiments of the present application, the packing ring 231 includes at least one of a ball ring, a Raschig ring or a Theta ring; the inner diameter of the packing ring 231 is 4 mm to 25 mm; specifically, it can be 4 mm, 8 mm, 10 mm, 15 mm, 18 mm, 20 mm, 22 mm, 25 mm or within the range of any two of the above values. In addition, in order to support the packing ring 231, a support frame (not shown in the figure) is also provided inside the tower body, and the support frame includes a bearing surface, and the packing ring 231 is stacked on the bearing surface, and the bearing surface is provided with through holes, so that the liquid can flow down smoothly, and the average diameter of the through holes is generally not more than 4 mm, and the porosity of the bearing surface is 95% to 98%. The "porosity" here refers to the proportion of the area of ​​all through holes to the area of ​​the entire bearing surface.

[0046] Example 1

[0047] In the composite extraction tower 001 of this embodiment, the total height of the tower body is 1500 mm, of which the tower top 100 is 300 mm high and has an inner diameter of 100 mm, the extraction section 200 is 900 mm high and has an inner diameter of 50 mm, and the tower bottom 300 is 300 mm high and has an inner diameter of 100 mm. The extraction section 200 contains 6 mass transfer parts 210, and in each mass transfer part 210, the length ratio of the liquid collecting area 220 to the liquid separation area 230 is 1:5. The interval between adjacent plate rings in the liquid collecting area 220 is 5 mm, and the packing rings 231 are all Raschig rings with an inner diameter of 10 mm. The average diameter of the through holes in the support surface is 3 mm, and the porosity is 95%.

[0048] Example 2

[0049] Compared with Example 1, the composite extraction tower of this embodiment mainly differs in that: the extraction section 200 contains three mass transfer elements 210, and in each mass transfer element 210, the length ratio of the liquid collecting area 220 to the liquid separation area 230 is 2:1. The interval between adjacent plate rings in the liquid collecting area 220 is 15 mm, and the packing rings 231 are all Raschig rings with an inner diameter of 4 mm. The average diameter of the through holes in the support surface is 2 mm, and the porosity is 98%.

[0050] Example 3

[0051] Compared with Example 1, the composite extraction tower of this embodiment mainly differs in that: the extraction section 200 contains two mass transfer members 210, and in each mass transfer member 210, the length ratio of the liquid collecting area 220 to the liquid separation area 230 is 3:1. The interval between adjacent plate rings in the liquid collecting area 220 is 30 mm, and the packing rings 231 are all Raschig rings with an inner diameter of 25 mm. The average diameter of the through holes in the support surface is 1 mm, and the porosity is 98%.

[0052] Comparative Example 1

[0053] Compared with Example 1, the main difference of this comparative example is that the extraction sections are all liquid separation zones, that is, the extraction sections are all filled with Raschig rings with an inner diameter of 6 mm.

[0054] Comparative Example 2

[0055] The main difference between this comparative example and Example 1 is that the entire extraction section is a liquid gathering zone, that is, the entire extraction section is filled with alternately distributed first baffles and second baffles.

[0056] Application Examples

[0057] The extraction tower in the embodiment and the comparative example is used to extract cesium from the lithium extraction mother liquor (lithium extraction mother liquor refers to the liquid waste containing lithium ions generated in the process of extracting lithium). The extract is a lithium extraction mother liquor with a cesium content of 0.65%, and the organic extraction solvent is a t-BAMBP extraction system, wherein the aqueous phase (heavy phase, with a higher density) is the continuous phase, and the organic phase (light phase, with a lower density) is the dispersed phase. The extraction conditions are Vc=1mm / s, Vd=2mm / s, and Af=8mm / s. After the extraction tower has been running continuously and stably for 2 hours, a sample is taken at the outlet of the heavy phase outlet pipe to determine the cesium concentration at the inlet and outlet of the heavy phase. At the same time, a sample is taken from the original extract to determine the cesium concentration at the inlet of the heavy phase. The cesium concentration of each sample to be tested is detected by the atomic absorption method, and the samples are taken in parallel three times to take the average value. The test results are used to calculate the extraction efficiency according to the following formula:

[0058]

[0059] in is the extraction efficiency of the extraction tower, is the cesium concentration at the heavy phase inlet, is the cesium concentration at the heavy phase outlet. The results are shown in Table 1

[0060] Table 1

[0061] Group Extraction efficiency Example 1 91% Example 2 93% Example 3 89% Comparative Example 1 73% Comparative Example 2 66%

[0062] It can be seen from Table 1 that the composite extraction tower in the present application has good separation effect and high extraction efficiency.

[0063] The above are only embodiments of the present application and are not intended to limit the scope of protection of the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the scope of protection of the present application.

Claims

1. A composite extraction tower, characterized in that: It comprises a tower body, which is composed of a tower top, an extraction section and a tower bottom from top to bottom, wherein the tower top is provided with a heavy phase liquid inlet pipe and a light phase liquid outlet pipe, and the tower bottom is provided with a light phase liquid inlet pipe and a heavy phase liquid outlet pipe; The extraction section is provided with at least one group of mass transfer components from top to bottom, each group of mass transfer components includes a liquid collecting area and a liquid separation area from top to bottom, a plurality of baffles are provided in the liquid collecting area, all of the baffles are distributed in sequence along the height direction of the tower body, and the liquid separation area is filled with packing rings for liquid separation; Along the height direction of the tower body, in each of the mass transfer elements, the ratio of the length of the liquid gathering zone to the length of the liquid separation zone is 5:1 to 1:5; The baffles include a first baffle and a second baffle, the first baffle and the second baffle are alternately distributed in the liquid collecting area along the height direction of the tower body, the edge of the first baffle is in contact with the inner wall of the tower body, and a liquid leakage port is arranged on the first baffle; the projection area of ​​the second baffle on the first baffle covers the liquid leakage port and is smaller than the area of ​​the first baffle; The spacing between adjacent baffles is 5 mm to 30 mm; A support frame for supporting the packing ring is also provided inside the tower body, the support frame includes a bearing surface, the packing ring is located on the bearing surface, and the bearing surface is provided with a through hole, the average diameter of the through hole is not greater than 4 mm, and the porosity of the bearing surface is 95% to 98%.

2. The composite extraction tower according to claim 1, characterized in that: The diameter of the tower top is greater than the diameter of the extraction section; and / or the diameter of the tower bottom is greater than the diameter of the extraction section.

3. The composite extraction tower according to claim 1, characterized in that: Taking the lowest point of the tower body as the horizontal plane, the height of the heavy phase liquid inlet pipe from the horizontal plane is less than the height of the light phase liquid outlet pipe from the horizontal plane, and the height of the heavy phase liquid outlet pipe from the horizontal plane is less than the height of the light phase liquid inlet pipe.

4. The composite extraction tower according to claim 1, characterized in that: The packing ring includes at least one of a ball ring, a Raschig ring or a Theta ring; and / or the inner diameter of the packing ring is 4 mm to 25 mm.

5. The composite extraction tower according to any one of claims 1 to 4, characterized in that: A pulse pipeline is also arranged at the bottom of the tower.

6. Use of the composite extraction tower according to any one of claims 1 to 5 in a chemical separation process.

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