An efficient packed extraction column

Abstract

The present invention relates to an efficient extraction column, which is a packed extraction column prepared from different materials. The packing is a combined packing. Based on the stretching and deformation of liquid droplets, the extraction column of the present invention has the advantages of high extraction efficiency, high liquid holdup, and large specific surface area of liquid droplets, etc.

Description

Technical Field

[0001] The present invention belongs to the field of extraction equipment, and particularly relates to a high-efficiency packed extraction column. Background Art

[0002] Liquid-liquid extraction columns have the advantages of simple structure, good sealing, large production capacity, etc., and are widely used in many fields such as petroleum, chemical industry, biology, medicine, and environmental engineering. The internal structure of the extraction column is to use gravity or mechanical action to break one liquid into droplets and disperse them in another continuous liquid for liquid-liquid extraction. In order to strengthen the liquid-liquid mixing in the extraction process, various types of extraction columns have been developed in the prior art, including sieve plate pulsed extraction columns, plate ring pulsed extraction columns, packed extraction columns, and rotating disc columns, etc. Among them, the packed extraction column has been widely used because of its low packing cost and no power consumption. However, most of the existing packings used are gas-liquid packings, and gas-liquid two-phase can be in full contact on almost all packing surfaces to achieve a relatively high mass transfer efficiency. In the liquid-liquid extraction process, mass transfer occurs between the fine dispersed phase droplet group and the continuous phase. Therefore, the extraction process requires the packing to be able to break the dispersed phase well to form a droplet group with uniform droplet diameters. If the dispersed phase droplets aggregate into a liquid layer on the packing surface, the mass transfer specific surface area will be greatly reduced, thus reducing the mass transfer efficiency.

[0003] The Chinese invention patent announcement text CN102847341B discloses a disc type liquid-liquid extraction column, which increases the interfacial contact area by specifically setting the disc, thereby improving the extraction efficiency. However, its structure is complex and no specific setting is made for the packing. Summary of the Invention

[0004] In view of the above technical problems, the object of the present invention is to propose a high-efficiency packed extraction column.

[0005] It is achieved by the following technical means:

[0006] A high-efficiency packed extraction column, which includes a top of the column, a packing section, and a bottom of the column.

[0007] The top of the column includes a top clarification space, an aqueous phase inlet, and an organic phase outlet; the diameter or equivalent diameter of the top clarification space is greater than the diameter or equivalent diameter of the packing section, and the aqueous phase inlet and the organic phase outlet are respectively opened on the side wall of the top clarification space.

[0008] The bottom of the column includes a bottom clarification space, an aqueous phase outlet, and an organic phase inlet; the diameter or equivalent diameter of the bottom clarification space is greater than the diameter or equivalent diameter of the packing section, and the aqueous phase outlet and the organic phase inlet are respectively opened on the side wall of the bottom clarification space.

[0009] The packing section is located between the top and bottom of the tower. The packing section includes a tower body, a packing group, and a support frame. The top of the tower body is hermetically connected to the bottom of the top of the tower, and the bottom of the tower body is hermetically connected to the top of the bottom of the tower. The support frame is provided at the bottom of the tower body, and the packing group is provided on the support frame. The support frame is used to support the packing group.

[0010] The packing group is formed by stacking multiple composite packing units. Each composite packing unit includes multiple layers of type I packing and / or multiple layers of type II packing. Among them, type I packing is a stainless steel wire with a diameter of 0.8 - 1.2 mm woven into a mesh structure and then pressed into a wavy mesh surface. Type II packing is a composite filament with a diameter of 0.85 - 1.25 mm woven into a mesh structure and then pressed into a wavy mesh surface. Multiple layers of type I packing form an I-I type combined packing, multiple layers of type II packing form an II-II type combined packing, and multiple layers of type I packing and multiple layers of type II packing are combined to form an I-II type combined packing. The composite packing unit is one or more combinations of an I-I type combined packing, an II-II type combined packing, or an I-II type combined packing.

[0011] Among them, the ratio of the number of layers of type I packing to the number of layers of type II packing in the I-II type combined packing is (3 - 5):(1 - 2).

[0012] When the interfacial tension (the interfacial tension between the organic phase and the aqueous phase) of the material to be treated is greater than the set interfacial tension threshold, the number of layers of type I packing in the packing group is less than the number of layers of type II packing. When the interfacial tension of the material to be treated is less than the set interfacial tension threshold, the number of layers of type I packing in the packing group is greater than the number of layers of type II packing. The interfacial tension threshold is 18.2 - 26.2 mN / m.

[0013] Preferably, the height position of the aqueous phase inlet is lower than the height position of the organic phase outlet; the height position of the aqueous phase outlet is lower than the height position of the organic phase inlet.

[0014] Preferably, the composite filament is a composite filament formed by coating a 0.3 - 0.6 mm stainless steel wire with polytetrafluoroethylene; the curved diameter of the wavy mesh surface is 0.8 - 6.2 cm.

[0015] Preferably, the top of the tower body is connected to the bottom of the top of the tower by a flange and hermetically connected by a sealing material. The bottom of the tower body is connected to the top of the bottom of the tower by a flange and hermetically connected by a sealing material.

[0016] Preferably, the packing group is formed by stacking 5 - 15 composite packing units.

[0017] Preferably, in each of the composite packing units, the II-II type combined packing is located in the upper part, the I-II type combined packing is located in the middle part, and the I-I type combined packing is located in the lower part.

[0018] Preferably, the support frame has a structure with densely distributed through holes, and the porosity of the support frame is 98-99.9%.

[0019] An efficient liquid-liquid extraction method uses the above-mentioned high-efficiency packing extraction tower, and includes the following steps:

[0020] (1) Assemble the packing section. Set the composite packing units according to the interfacial tension of the material to be processed. When the interfacial tension of the material to be processed is greater than the set interfacial tension threshold, the ratio of the II-II type combined packing: I-II type combined packing: I-I type combined packing in the composite packing unit is (7.5-8.5):(1.5-2.5):(0.5-1.5). When the interfacial tension of the material to be processed is less than the set interfacial tension threshold, the ratio of the II-II type combined packing: I-II type combined packing: I-I type combined packing in the composite packing unit is (0.5-1.5):(1.5-2.5):(7.5-8.5). The interfacial tension threshold is 18.2-26.2 mN / m. Then vertically fill 5-15 of the composite packing units in the packing section to form the packing group, and the assembly of the packing section is completed.

[0021] (2) Fill the tower. First, close the water phase outlet, and fill the high-efficiency packing extraction tower with fresh organic phase feed liquid through the organic phase inlet. The liquid level height after filling the fresh organic phase feed liquid is between the organic phase outlet and the water phase inlet in the top clarification space of the tower.

[0022] (3) Liquid-liquid extraction. Open the water phase inlet and discharge the water phase feed liquid into the high-efficiency packing extraction tower. When the two-phase interface of the organic phase feed liquid and the water phase feed liquid is between the organic phase outlet and the water phase inlet in the top clarification space of the tower, open the water phase outlet and keep the flow rate of the water phase feed liquid at the water phase inlet the same as or substantially the same as the flow rate of the feed liquid at the water phase outlet. Then continuously introduce the water phase feed liquid through the water phase inlet and introduce the organic phase feed liquid through the organic phase inlet to carry out liquid-liquid extraction.

[0023] Preferably, in step (1), the interfacial tension threshold is preferably 22.2-25.1 mN / m; preferably, 8-11 of the composite packing units are vertically filled in the packing section.

[0024] Preferably, in step (1), when the interfacial tension of the material to be processed is greater than the set interfacial tension threshold, the ratio of the II-II type combined packing: I-II type combined packing: I-I type combined packing in the composite packing unit is preferably (7.8 - 8.2):(1.8 - 2.2):(0.8 - 1.2); when the interfacial tension of the material to be processed is less than the set interfacial tension threshold, the ratio of the II-II type combined packing: I-II type combined packing: I-I type combined packing in the composite packing unit is (0.8 - 1.2):(1.8 - 2.2):(7.8 - 8.2).

[0025] The technical effect of the present invention lies in that:

[0026] By specifically setting and assembling the packing method of the extraction tower with a specific structure, and by using specific different forms of packing, the aqueous phase droplets can be effectively coalesced on the surfaces of the type I packing and type II packing and broken due to the non-wetting characteristics of the packing. The above characteristics achieved by the specific setting of the present invention not only realize the effective breaking and coalescence of the droplets during the extraction movement process of the droplets; at the same time, based on the characteristics of the interfacial tension and wettability of the droplets, the droplets are stretched and spread on the corresponding packing surfaces, thereby increasing the mass transfer specific surface area and then improving the mass transfer efficiency.

[0027] By adopting different packing arrangement methods for materials with different interfacial tensions, the present invention can enable the packing methods in different liquid-liquid extraction processes to achieve the optimal mass transfer efficiency for different materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a schematic structural diagram of a high-efficiency extraction tower in one embodiment.

[0029] Wherein: 1 - top of the tower; 2 - water phase inlet; 3 - water phase outlet; 4 - organic phase inlet; 5 - organic phase outlet; 6 - packing group; 7 - bottom clarification space of the tower; 8 - top clarification space of the tower; 9 - tower body of the packing section; 10 - support frame; 11 - bottom of the tower. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0030] The process technical solutions of the present invention will be further described below by combining examples and drawings. Unless otherwise stated, each feature is just an example in a series of equivalent or similar features. It is only for helping to understand the present invention. Those skilled in the art should understand that the described examples are only for helping to understand the present invention and should not be regarded as specific limitations to the present invention.

[0031] Example 1

[0032] The interfacial tension threshold set in this embodiment is 24.6 mN / m. The material processed in this embodiment has a small interfacial tension, and the specific interfacial tension is 10.23 mN / m (less than the set interfacial tension threshold). The total packing height in the liquid-liquid extraction column is 1 m. The packing used is a combined packing, and the combined packing method: the ratio of the thicknesses of each layer is the multi-layer superposition layer of II-II: the cyclic multi-layer superposition layer of multi-layer I-II: the multi-layer superposition layer of multi-layer I-I is 1:2:8, and the packing height is 10 cm high. Ten are filled in the same combination method, that is, the total packing height is 1 m.

[0033] As Figure 1 shown, the high-efficiency packing extraction column includes a top tower, a packing section, and a bottom tower; the top tower includes a top tower clarification space, an aqueous phase inlet, and an organic phase outlet; the diameter or equivalent diameter of the top tower clarification space is greater than the diameter or equivalent diameter of the packing section, and the aqueous phase inlet and the organic phase outlet are respectively opened on the side wall of the top tower clarification space; the bottom tower includes a bottom tower clarification space, an aqueous phase outlet, and an organic phase inlet; the diameter or equivalent diameter of the bottom tower clarification space is greater than the diameter or equivalent diameter of the packing section, and the aqueous phase outlet and the organic phase inlet are respectively opened on the side wall of the bottom tower clarification space; the packing section is located between the top tower and the bottom tower. The packing section includes a tower body, a packing group, and a support frame. The top of the tower body is hermetically connected to the bottom of the top tower, and the bottom of the tower body is hermetically connected to the top of the bottom tower. The support frame is arranged at the bottom of the tower body, and the packing group is arranged on the support frame. The support frame is used to support the packing group;

[0034] The packing group is formed by stacking multiple composite packing units. Each composite packing unit includes multiple layers of type I packing and / or multiple layers of type II packing; among them, type I packing is a stainless steel wire with a diameter of 0.8 - 1.2 mm woven into a mesh structure and then pressed into a corrugated mesh surface, and type II packing is a composite filament with a diameter of 0.85 - 1.25 mm woven into a mesh structure and then pressed into a corrugated mesh surface. Multiple layers of type I packing form an I-I type combined packing, multiple layers of type II packing form an II-II type combined packing, and multiple layers of type I packing and multiple layers of type II packing are combined to form an I-II type combined packing; the composite packing unit is one or more combinations of an I-I type combined packing, an II-II type combined packing, or an I-II type combined packing.

[0035] Among them, the ratio of the number of layers of type I packing to the number of layers of type II packing in the I-II type combined packing is 5:1.

[0036] As Figure 1 shown, the height position of the aqueous phase inlet is lower than the height position of the organic phase outlet; the height position of the aqueous phase outlet is lower than the height position of the organic phase inlet.

[0037] AsFigure 1 As shown, the top of the tower body is connected to the bottom of the tower top through a flange and is hermetically connected through a sealing material. The bottom of the tower body is connected to the top of the tower bottom through a flange and is hermetically connected through a sealing material.

[0038] And in this embodiment, in each of the composite packing units, the II-II type combined packing is located in the upper part, the I-II type combined packing is located in the middle part, and the I-I type combined packing is located in the lower part.

[0039] The type I packing in this embodiment is a stainless steel wire with a diameter of 1 mm, and the type II packing is a composite filament formed by coating a 0.5-mm stainless steel wire with polytetrafluoroethylene. The coating layer of polytetrafluoroethylene makes the diameter of the composite filament of the type II packing 1.05 mm. The bending angle between adjacent packing wires in the mesh structure formed by the type I packing and the type II packing is 20-60°, and the length of each bent section is 6-9 mm.

[0040] When the interfacial tension of the material to be treated is greater than or equal to the interfacial tension threshold, the bending angle between adjacent packing wires in the mesh structure is 45-60°; when the interfacial tension of the material to be treated is less than the interfacial tension threshold, the bending angle between adjacent packing wires in the mesh structure is 20-45°. For this embodiment, 30° is selected.

[0041] The curved surface diameter of the corrugated mesh surface is 0.8-6.2 cm. And when the interfacial tension of the material to be treated is greater than or equal to the interfacial tension threshold, the diameter of the corrugated mesh surface is 3-6.2 cm; when the interfacial tension of the material to be treated is less than the interfacial tension threshold, the diameter of the corrugated mesh surface is 0.8-3 cm. For this embodiment, 1.9 cm is selected.

[0042] When the interfacial tension of the material to be treated is greater than the set interfacial tension threshold, the number of layers of the type I packing in the packing group is less than the number of layers of the type II packing. When the interfacial tension of the material to be treated is less than the set interfacial tension threshold, the number of layers of the type I packing in the packing group is greater than the number of layers of the type II packing. As above, in this embodiment, the ratio of the thicknesses of each layer is the multi-layer superposition layer of II-II: the cyclic multi-layer superposition layer of multi-layer I-II: the multi-layer superposition layer of multi-layer I-I is 1:2:8, that is, the number of layers of the type I packing is greater than the number of layers of the type II packing.

[0043] Example 2

[0044] This embodiment is an efficient liquid-liquid extraction method using the device of Example 1. The efficient liquid-liquid extraction method is carried out using the above-mentioned high-efficiency packing extraction tower, and includes the following steps:

[0045] (1) Assemble the packing section, and complete the assembly of the packing section according to the packing setting method of Example 1.

[0046] (2) Tower filling: First, close the aqueous phase outlet, and fill the high-efficiency packed extraction tower with fresh organic phase feed solution through the organic phase inlet. The liquid level height after filling the fresh organic phase feed solution is located in the top clarification space between the organic phase outlet and the aqueous phase inlet.

[0047] (3) Liquid-liquid extraction: Open the aqueous phase inlet and discharge the aqueous phase feed solution into the high-efficiency packed extraction tower. When the two-phase interface of the organic phase feed solution and the aqueous phase feed solution is located in the top clarification space between the organic phase outlet and the aqueous phase inlet, open the aqueous phase outlet and keep the flow rate of the aqueous phase feed solution at the aqueous phase inlet the same as or substantially the same as the flow rate of the feed solution at the aqueous phase outlet; then continuously introduce the aqueous phase feed solution through the aqueous phase inlet and introduce the organic phase feed solution through the organic phase inlet to carry out liquid-liquid extraction.

[0048] With the above settings in this embodiment, the extraction efficiency can reach 88%.

[0049] Comparative Example 1

[0050] The other setting methods in this comparative example are the same as those in Example 1 and Example 2. The difference is that a single type I packing is used for packing, and type II packing is not set. After the same time of extraction treatment is carried out by using the same liquid-liquid extraction method as in Example 2, the extraction efficiency of this comparative example is 72%, which is significantly lower than that of Example 2, indicating that the specific cooperation method of the specific type I and type II packings of the present invention can improve the extraction efficiency.

[0051] Comparative Example 2

[0052] The other setting methods in this comparative example are the same as those in Example 1 and Example 2. The difference is that the ratio of the thicknesses of each layer is 8:2:1 for the multi-layer stack of II-II: the multi-layer cyclic multi-layer stack of I-II: the multi-layer stack of I-I, that is, the materials with small interfacial tension in Example 1 are stacked in the opposite way to that in Example 1. After the same time of extraction treatment is carried out by using the same liquid-liquid extraction method as in Example 2, the extraction efficiency of this comparative example is 67%, which is significantly lower than that of Example 2, indicating that the setting and cooperation method of each packing of the present invention can improve the extraction efficiency.

Claims

1. An efficient packed extraction column, characterized in that, The high-efficiency packed extraction column includes a top tower, a packing section, and a bottom tower; The top tower includes a top clarification space, an aqueous phase inlet, and an organic phase outlet; the diameter or equivalent diameter of the top clarification space is greater than the diameter or equivalent diameter of the packing section, and both the aqueous phase inlet and the organic phase outlet are respectively opened on the side wall of the top clarification space; The bottom tower includes a bottom clarification space, an aqueous phase outlet, and an organic phase inlet; the diameter or equivalent diameter of the bottom clarification space is greater than the diameter or equivalent diameter of the packing section, and both the aqueous phase outlet and the organic phase inlet are respectively opened on the side wall of the bottom clarification space; The packing section is located between the top tower and the bottom tower. The packing section includes a tower body, a packing group, and a support frame. The top of the tower body is hermetically connected to the bottom of the top tower, and the bottom of the tower body is hermetically connected to the top of the bottom tower. The support frame is arranged at the bottom of the tower body, and the packing group is arranged on the support frame. The support frame is used to support the packing group; The packing group is formed by stacking multiple composite packing units. Each composite packing unit includes multiple layers of type I packing and multiple layers of type II packing; among them, type I packing is a stainless steel wire with a diameter of 0.8 - 1.2 mm woven into a mesh structure and then pressed into a wavy mesh surface, and type II packing is a composite filament with a diameter of 0.85 - 1.25 mm woven into a mesh structure and then pressed into a wavy mesh surface. Multiple layers of type I packing form an I-I type combined packing, multiple layers of type II packing form an II-II type combined packing, and multiple layers of type I packing and multiple layers of type II packing are combined to form an I-II type combined packing; Among them, the ratio of the number of layers of type I packing to the number of layers of type II packing in the I-II type combined packing is (3 - 5):(1 - 2); When the interfacial tension of the material to be processed is greater than the set interfacial tension threshold, the number of layers of type I packing in the packing group is less than the number of layers of type II packing. When the interfacial tension of the material to be processed is less than the set interfacial tension threshold, the number of layers of type I packing in the packing group is greater than the number of layers of type II packing. The interfacial tension threshold is 18.2 - 26.2 mN / m; In each composite packing unit, the II-II type combined packing is located in the upper part, the I-II type combined packing is located in the middle part, and the I-I type combined packing is located in the lower part.

2. The high-efficiency packed extraction column according to claim 1, wherein The height position of the aqueous phase inlet is lower than the height position of the organic phase outlet; the height position of the aqueous phase outlet is lower than the height position of the organic phase inlet.

3. The high-efficiency packed extraction column according to claim 1, wherein The composite filament is a composite filament formed by coating a 0.3 - 0.6 mm stainless steel wire with polytetrafluoroethylene; the curved diameter of the wavy mesh surface is 0.8 - 6.2 cm.

4. The high-efficiency packed extraction column according to claim 1, characterized in that, The top of the tower body is connected to the bottom of the top tower through a flange and is hermetically connected through a sealing material. The bottom of the tower body is connected to the top of the bottom tower through a flange and is hermetically connected through a sealing material.

5. The high-efficiency packed extraction column according to claim 1, wherein The packing group is formed by stacking 5 - 15 composite packing units.

6. The high-efficiency packed extraction column according to claim 1, wherein The support frame is a structure with densely distributed through holes, and the porosity of the support frame is 98 - 99.9%; 7. An efficient liquid-liquid extraction method, characterized in that, The high-efficiency liquid-liquid extraction method is carried out using the high-efficiency packed extraction column according to any one of claims 1 - 6, and includes the following steps: (1) Assemble the packing section. Set the composite packing units according to the interfacial tension of the material to be processed. When the interfacial tension of the material to be processed is greater than the set interfacial tension threshold, the ratio of type II-II combined packing : type I-II combined packing : type I-I combined packing in the composite packing unit is (7.5 - 8.5) : (1.5 - 2.5) : (0.5 - 1.5). When the interfacial tension of the material to be processed is less than the set interfacial tension threshold, the ratio of type II-II combined packing : type I-II combined packing : type I-I combined packing in the composite packing unit is (0.5 - 1.5) : (1.5 - 2.5) : (7.5 - 8.5). The interfacial tension threshold is 18.2 - 26.2 mN / m. Then vertically fill 5 - 15 of the said composite packing units in the packing section to form the packing group, and the assembly of the packing section is completed. (2) Fill the tower. First, close the water phase outlet, and fill fresh organic phase feed liquid into the high-efficiency packed extraction tower through the organic phase inlet. The liquid level height after filling the fresh organic phase feed liquid is located in the top clarifying space between the organic phase outlet and the water phase inlet. (3) Liquid-liquid extraction. Open the water phase inlet and discharge water phase feed liquid into the high-efficiency packed extraction tower. When the two-phase interface of the organic phase feed liquid and the water phase feed liquid is located in the top clarifying space between the organic phase outlet and the water phase inlet, open the water phase outlet, and keep the water phase feed liquid flow rate at the water phase inlet the same or substantially the same as the liquid flow rate at the water phase outlet. Then continuously introduce water phase feed liquid through the water phase inlet and introduce organic phase feed liquid through the organic phase inlet for liquid-liquid extraction.

8. The high-efficiency liquid-liquid extraction method according to claim 7, wherein, In step (1), the interfacial tension threshold is 22.2 - 25.1 mN / m; 8 - 11 of the said composite packing units are vertically filled in the packing section.

9. The high-efficiency liquid-liquid extraction method according to claim 7, wherein In step (1), when the interfacial tension of the material to be processed is greater than the set interfacial tension threshold, the ratio of type II-II combined packing : type I-II combined packing : type I-I combined packing in the composite packing unit is (7.8 - 8.2) : (1.8 - 2.2) : (0.8 - 1.2). When the interfacial tension of the material to be processed is less than the set interfacial tension threshold, the ratio of type II-II combined packing : type I-II combined packing : type I-I combined packing in the composite packing unit is (0.8 - 1.2) : (1.8 - 2.2) : (7.8 - 8.2).

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