A Stirring Sieve Plate Extraction Column and Its Application in Extraction Systems with Medium to High Interfacial Tension

Abstract

The present invention discloses a stirred sieve plate extraction column and a method for its application in a medium-high interfacial tension extraction system. The stirred sieve plate extraction column is alternately composed of a stirring section and a clarification section. Sieve plates are provided at both ends of the stirring section. Step holes are evenly formed on the sieve plates, or non-through grooves are formed on one side of the sieve plates, and holes are evenly formed in the non-through grooves. The large holes of the step holes face the clarification section, and the small holes face the stirring section. The non-through grooves with evenly formed holes in the non-through grooves face the clarification section, and the holes face the stirring section. Due to the adoption of the way of step holes or evenly formed holes in the non-through grooves on the sieve plates, the equipment throughput of this stirred sieve plate extraction column can be greatly increased, the operating flexibility is large, and the equipment volumetric efficiency is high. In addition, when the dispersed phase flows through the stirring section and the clarification section from bottom to top or from top to bottom, it is easier to be dispersed into relatively uniform small droplets. Therefore, the mass transfer specific surface area is large and the extraction efficiency is high, solving the problem that the equipment throughput and extraction efficiency in the sieve plate extraction column in the medium-high interfacial tension extraction system cannot be taken into account at the same time.

Description

Technical Field

[0001] The present invention belongs to the field of extraction and separation, and relates to a stirred sieve plate extraction column and its application in an extraction system with medium to high interfacial tension. Background Art

[0002] Sieve plate extraction columns are an important type of separation equipment and have wide applications in the chemical industry. Traditional sieve plate extraction columns are typical stage-wise contact equipment. The entire column consists of a series of sieve plates arranged. Generally, sieve plates with downcomers (or risers) are used. In addition, there are also sieve plate extraction columns without the structure of downcomers, that is, perforated plate extraction columns. Since there are no downcomers, the two phases are in countercurrent contact rather than cross-flow contact on the sieve plates, saving the space occupied by the downcomers and improving the volumetric efficiency. However, the operating flexibility is smaller than that of sieve plates with downcomers.

[0003] To solve the problem of insufficient liquid-liquid dispersion in traditional sieve plate extraction columns, sieve plate extraction columns with externally applied energy have been developed. The pulsed sieve plate extraction column is one of the widely used extraction equipment with externally applied energy. The most important feature is that a pulse generator is provided at the bottom of the column. The sieve plates used in pulsed sieve plate extraction columns generally do not contain downcomers, that is, perforated sieve plates. Therefore, compared with traditional sieve plate extraction columns, the allowable flux is smaller. However, due to the externally applied energy promoting dispersion and mass transfer, the height of the mass transfer unit is smaller and the mass transfer efficiency is high. The structure of the vibrating sieve plate extraction column is similar to that of the pulsed sieve plate extraction column. The difference is that the vibrating sieve plate extraction column does not have a pulse generator at the bottom of the column. Instead, a mechanical reciprocating motion mechanism is set at the top of the column to drive the sieve plates in the column to vibrate up and down. During operation, the hydrodynamic state of the two-phase fluids is similar to that of the pulsed sieve plate extraction column. The difference is that the vibrating sieve plate extraction column forces the dispersed phase to disperse due to the up and down reciprocating motion of the sieve plates, thereby improving the mass transfer efficiency.

[0004] To further solve the problems of liquid-liquid dispersion and axial backmixing, the Scheibel extraction column with sieve plates (CN101693151) and the stirred sieve plate extraction column (Journal of Chemical Engineering of Chinese Universities, 2021, 35(4): 601-607) have been developed successively. Research shows that the backmixing of the above two extraction columns has been effectively inhibited, and the problem of liquid-liquid dispersion has also been well solved, with relatively high extraction efficiency. However, the overall equipment flux is small and the volumetric utilization rate is low. When the required treatment volume is large, the equipment is huge, restricting its application range. Summary of the Invention

[0005] The purpose of the present invention is to overcome the deficiencies of the prior art and provide a stirred sieve plate extraction column and a method for its application in an extraction system with medium to high interfacial tension.

[0006] The stirred sieve plate extraction column provided by the present invention is alternately composed of a stirring section and a clarification section along the height direction of the column, and sieve plates are provided at both ends of the stirring section.

[0007] According to one embodiment of the present invention, stepped holes are evenly provided on the sieve plate, wherein the large holes of the stepped holes face the clarification section and the small holes face the stirring section.

[0008] Furthermore, the large hole diameter of the stepped holes is 3-15 mm, the large hole depth is 50-95% of the sieve plate thickness, the small hole diameter is 2-4 mm, the small hole depth is 5-50% of the sieve plate thickness, and the opening rate of the small holes is 5-30%.

[0009] According to another embodiment of the present invention, a non-through groove is opened on one side of the sieve plate, and holes are uniformly opened in the non-through groove. The non-through groove faces the clarification section, and the uniform openings in the non-through groove face the stirring section.

[0010] Furthermore, the width of the above-mentioned non-through groove is 2-12 mm, the depth of the non-through groove is 50-95% of the thickness of the sieve plate, the hole is arranged in the non-through groove, the hole diameter is less than or equal to the width of the non-through groove, the diameter of the hole is 2-4 mm, the depth of the hole is 5-50% of the thickness of the sieve plate, and the opening rate in terms of holes is 5-30%.

[0011] Furthermore, the non-through groove can be in the form of an annular groove, a linear groove, a waist-shaped groove, etc.

[0012] According to a preferred embodiment of the present invention, the thickness of the sieve plate is 2-20 mm.

[0013] The present invention also discloses the use of the above-mentioned stirred sieve plate extraction tower in the extraction of medium-high interfacial tension extraction systems. The medium-high interfacial tension extraction system refers to a system with an interfacial tension greater than or equal to 3 mN / m. Typical but not limiting examples include toluene-methanol-water systems, toluene-propanol-water systems, toluene-acetic acid-water systems, hexane-methanol-water systems, hexane-ethanol-water systems, heptane-propanol-water systems, octanol-propanol-water systems, octane-n-butanol-ethanol-water systems, and nonane-n-pentanol-ethanol-water systems.

[0014] The advantages of this invention are that, for systems with medium to high interfacial tension, the sieve plates employ stepped holes or uniformly perforated non-through slots, significantly increasing equipment throughput, providing greater operational flexibility and high volumetric efficiency. Furthermore, the dispersed phase is more easily dispersed into relatively uniform small droplets as it flows from bottom to top or top to bottom through the stirring and clarification sections, resulting in a large specific surface area for mass transfer and high extraction efficiency. This solves the problem of balancing equipment throughput and extraction efficiency in sieve plate extraction towers for systems with medium to high interfacial tension. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a schematic diagram of the structure of a stirred sieve plate extraction tower.

[0016] Figure 2 andFigure 3 Schematic diagram of grooving and hole-opening methods with uniformly opened holes in non-through grooves. Specific implementation manner

[0017] The structural schematic diagram of the stirring sieve plate extraction tower of the present invention is as Figure 1 shown. It is composed of alternating stirring sections and clarification sections along the tower height direction. Sieve plates are provided at both ends of the stirring section. Step holes are uniformly opened on the sieve plates, or a non-through groove is opened on one side of the sieve plate, and uniformly opened holes are arranged in the non-through groove; the large holes of the step holes face the clarification section, the small holes face the stirring section, the non-through groove faces the clarification section, and the uniformly opened holes in the non-through groove face the stirring section.

[0018] In a preferred implementation manner of the present invention, the diameter of the large holes of the above step holes is 3 - 15 mm, the depth of the large holes is 50 - 95% of the sieve plate thickness, the diameter of the small holes is 2 - 4 mm, the depth of the small holes is 5 - 50% of the sieve plate thickness, and the hole-opening rate calculated by the small holes is 5 - 30%.

[0019] In another preferred implementation manner of the present invention, the grooving and hole-opening methods with uniformly opened holes in the above non-through groove are as Figure 2 or Figure 3 shown. The width of the non-through groove is 2 - 12 mm, the depth of the non-through groove is 50 - 95% of the sieve plate thickness, the holes are arranged in the non-through groove, the hole diameter is less than or equal to the width of the non-through groove, the diameter of the holes is preferably 2 - 4 mm, the depth of the holes is 5 - 50% of the sieve plate thickness, and the hole-opening rate calculated by the holes is 5 - 30%.

[0020] According to the preferred embodiment of the present invention, the non-through groove can be Figure 2 the circular ring groove shown, or can be Figure 3 the linear groove shown, or other forms of grooves. The selection of the groove shape should be as convenient for processing as possible. The thickness of the sieve plate of the present invention can be selected as 2 - 20 mm.

[0021] Example 1

[0022] As Figure 1The shown agitated sieve-plate extraction column has a diameter of 50 mm, with a total of 3 agitation sections and 4 clarification sections. The height of the agitation section is 35 mm, the height of the clarification section is 50 mm, the sieve-plate thickness is 2 mm. The sieve plate is evenly provided with stepped holes. The large holes of the stepped holes face the clarification section, and the small holes face the agitation section. The diameter of the large holes is 4 mm, and the depth of the large holes is 1 mm (50% of the sieve-plate thickness). The diameter of the small holes is 3 mm, and the depth of the small holes is 1 mm (50% of the sieve-plate thickness). The opening ratio based on the small holes is 10%. Using the toluene-propanol-water system with high interfacial tension (interfacial tension is 32.4 mN / m) as the research object, a toluene solution with a mass fraction of 10% of propanol is pumped into the light-phase inlet as the dispersed phase, and pure water is pumped into the heavy-phase inlet as the continuous phase. The solvent ratio is 1. When the rotational speed is 380 rpm and the total flow rate of the two phases is 60 mL / min, the extraction theoretical stage number is 2.03 stages, and the maximum throughput of the extraction column is 10.7 m 3 / (m 2 ·hr).

[0023] Example 2

[0024] As Figure 1 shown, the agitated sieve-plate extraction column has a diameter of 50 mm, with a total of 3 agitation sections and 4 clarification sections. The height of the agitation section is 35 mm, the height of the clarification section is 50 mm, the sieve-plate thickness is 2 mm. The sieve plate is evenly opened with holes in the non-through slots. The slotting and hole-opening methods are as Figure 2 shown. The non-through slots face the clarification section, and the holes face the agitation section. The width of the non-through slots is 4 mm, the depth of the non-through slots is 1 mm (50% of the sieve-plate thickness), the diameter of the holes is 3 mm, and the depth of the holes is 1 mm (50% of the sieve-plate thickness). The opening ratio based on the holes is 10%. Using the toluene-propanol-water system with high interfacial tension (interfacial tension is 32.4 mN / m) as the research object, a toluene solution with a mass fraction of 10% of propanol is pumped into the light-phase inlet as the dispersed phase, and pure water is pumped into the heavy-phase inlet as the continuous phase. The solvent ratio is 1. When the rotational speed is 380 rpm and the total flow rate of the two phases is 60 mL / min, the extraction theoretical stage number is 1.96 stages, and the maximum throughput of the extraction column is 11.4 m 3 / (m 2 ·hr).

[0025] Example 3

[0026] As Figure 1 shown, the agitated sieve-plate extraction column has a diameter of 50 mm, with a total of 3 agitation sections and 4 clarification sections. The height of the agitation section is 35 mm, the height of the clarification section is 50 mm, the sieve-plate thickness is 2 mm. The sieve plate is evenly opened with holes in the non-through slots. The slotting and hole-opening methods are as Figure 3As shown, the non-through groove faces the clarification section, the holes face the agitation section. The width of the non-through groove is 2 mm, the depth of the non-through groove is 1 mm (50% of the sieve plate thickness), the diameter of the holes is 2 mm, the depth of the holes is 1 mm (50% of the sieve plate thickness), and the hole opening ratio by number of holes is 30%. Using the toluene-propanol-water system with high interfacial tension (interfacial tension is 32.4 mN / m) as the research object, a toluene solution with a propanol mass fraction of 10% is pumped into the light-phase inlet as the dispersed phase, and pure water is pumped into the heavy-phase inlet as the continuous phase. The solvent ratio is 1. When the rotational speed is 380 rpm and the total flow rate of the two phases is 60 mL / min, the extraction theoretical stage number is 1.93 stages, and the maximum throughput of the extraction column is 13.8 m 3 / (m 2 ·hr).

[0027] Example 4

[0028] As Figure 1 shown, the agitated sieve plate extraction column has a diameter of 100 mm, a total of 6 agitation sections and 7 clarification sections. The height of the agitation section is 70 mm, the height of the clarification section is 80 mm, the sieve plate thickness is 10 mm, and the sieve plate is uniformly perforated in the non-through groove. The grooving and perforating methods are as Figure 3 shown. The non-through groove faces the clarification section, the holes face the agitation section. The width of the non-through groove is 6 mm, the depth of the non-through groove is 7 mm (70% of the sieve plate thickness), the diameter of the holes is 4 mm, the depth of the holes is 3 mm (30% of the sieve plate thickness), and the hole opening ratio by number of holes is 15%. Using the toluene-propanol-water system with high interfacial tension (interfacial tension is 32.4 mN / m) as the research object, a toluene solution with a propanol mass fraction of 10% is pumped into the light-phase inlet as the dispersed phase, and pure water is pumped into the heavy-phase inlet as the continuous phase. The solvent ratio is 1. When the rotational speed is 200 rpm and the total flow rate of the two phases is 200 mL / min, the extraction theoretical stage number is 3.87 stages, and the maximum throughput of the extraction column is 15.3 m 3 / (m 2 ·hr).

[0029] Example 5

[0030] As Figure 1The shown agitated sieve-plate extraction column has a diameter of 100 mm, with a total of 6 agitation sections and 7 clarification sections. The height of the agitation section is 70 mm, the height of the clarification section is 80 mm, the thickness of the sieve plate is 10 mm. Step holes are evenly opened on the sieve plate. The large holes of the step holes face the clarification section, and the small holes face the agitation section. The diameter of the large holes is 10 mm, and the depth of the large holes is 9 mm (90% of the sieve plate thickness). The diameter of the small holes is 4 mm, and the depth of the small holes is 1 mm (10% of the sieve plate thickness). The hole opening rate calculated by the small holes is 5%. Using the octanol-propanol-water system with medium interfacial tension (interfacial tension is 5.6 mN / m) as the research object, an octanol solution with a propanol mass fraction of 10% is pumped into the light-phase inlet as the dispersed phase, and pure water is pumped into the heavy-phase inlet as the continuous phase. The solvent ratio is 1. When the rotation speed is 160 rpm and the total flow rate of the two phases is 200 mL / min, the extraction theoretical stage number is 2.64 stages, and the maximum flux of the extraction column is 17.1 m 3 / (m 2 ·hr).

[0031] Example 6

[0032] As Figure 1 The shown agitated sieve-plate extraction column has a diameter of 100 mm, with a total of 6 agitation sections and 7 clarification sections. The height of the agitation section is 70 mm, the height of the clarification section is 80 mm, the thickness of the sieve plate is 4 mm. Step holes are evenly opened on the sieve plate. The large holes of the step holes face the clarification section, and the small holes face the agitation section. The diameter of the large holes is 3 mm and the depth of the large holes is 2 mm (50% of the sieve plate thickness). The diameter of the small holes is 2 mm and the depth of the small holes is 2 mm (50% of the sieve plate thickness). The hole opening rate calculated by the small holes is 30%. Using the octanol-propanol-water system with medium interfacial tension (interfacial tension is 5.6 mN / m) as the research object, an octanol solution with a propanol mass fraction of 10% is pumped into the light-phase inlet as the dispersed phase, and pure water is pumped into the heavy-phase inlet as the continuous phase. The solvent ratio is 1. When the rotation speed is 160 rpm and the total flow rate of the two phases is 200 mL / min, the extraction theoretical stage number is 2.58 stages, and the maximum flux of the extraction column is 18.5 m 3 / (m 2 ·hr).

[0033] Example 7

[0034] As Figure 1The shown compound sieve plate extraction column has a diameter of 300 mm, with a total of 3 stirring sections and 4 clarification sections. The height of the stirring section is 120 mm, the height of the clarification section is 180 mm, the thickness of the sieve plate is 20 mm. The sieve plate is evenly provided with stepped holes. The large holes of the stepped holes face the clarification section, and the small holes face the stirring section. The diameter of the large holes is 15 mm, the depth of the large holes is 19 mm (95% of the sieve plate thickness), the diameter of the small holes is 4 mm, the depth of the small holes is 1 mm (5% of the sieve plate thickness), and the opening ratio based on the small holes is 5%. Taking the octanol-propanol-water system with medium interfacial tension (interfacial tension is 5.6 mN / m) as the research object, an octanol solution with a propanol mass fraction of 10% is pumped into from the light phase inlet as the dispersed phase, and pure water is pumped into from the heavy phase inlet as the continuous phase. The solvent ratio is 1. When the rotation speed is 50 rpm and the total flow rate of the two phases is 1500 mL / min, the extraction theoretical stage number is 1.27 stages, and the maximum throughput of the extraction column is 16.2 m 3 / (m 2 ·hr).

[0035] Example 8

[0036] As Figure 1 shown, the compound sieve plate extraction column has a diameter of 300 mm, with a total of 3 stirring sections and 4 clarification sections. The height of the stirring section is 120 mm, the height of the clarification section is 180 mm, the thickness of the sieve plate is 20 mm. The sieve plate is evenly opened with holes in the non-through groove, and the grooving and hole-opening methods are as Figure 3 shown. The non-through groove faces the clarification section, and the holes face the stirring section. The width of the non-through groove is 12 mm, the depth of the non-through groove is 19 mm (95% of the sieve plate thickness), the diameter of the holes is 4 mm, the depth of the holes is 1 mm (5% of the sieve plate thickness), and the opening ratio based on the holes is 5%. Taking the octanol-propanol-water system with medium interfacial tension (interfacial tension is 5.6 mN / m) as the research object, an octanol solution with a propanol mass fraction of 10% is pumped into from the light phase inlet as the dispersed phase, and pure water is pumped into from the heavy phase inlet as the continuous phase. The solvent ratio is 1. When the rotation speed is 50 rpm and the total flow rate of the two phases is 1500 mL / min, the extraction theoretical stage number is 1.22 stages, and the maximum throughput of the extraction column is 16.7 m 3 / (m 2 ·hr).

[0037] Comparative Example 1

[0038] Keep other parameters the same as in Example 1, only change the orientation of the stepped hole, make the small hole of the stepped hole face the clarification section, and the large hole face the stirring section. Take the toluene-propanol-water system with high interfacial tension (interfacial tension is 32.4 mN / m) as the research object. Pump a toluene solution with a mass fraction of 10% of propanol into the light-phase inlet as the dispersed phase, and pump pure water into the heavy-phase inlet as the continuous phase. The solvent ratio is 1. When the rotation speed is 380 rpm and the total flow rate of the two phases is 60 mL / min, the extraction theoretical stage number is 1.73 stages, and the maximum flux of the extraction column is 5.2 m 3 / (m 2 ·hr).

[0039] Comparative Example 2

[0040] Keep other parameters the same as in Example 1, only change the large hole diameter of the stepped hole to be the same as the small hole, that is, both are 3 mm. Take the toluene-propanol-water system with high interfacial tension (interfacial tension is 32.4 mN / m) as the research object. Pump a toluene solution with a mass fraction of 10% of propanol into the light-phase inlet as the dispersed phase, and pump pure water into the heavy-phase inlet as the continuous phase. The solvent ratio is 1. When the rotation speed is 380 rpm and the total flow rate of the two phases is 60 mL / min, the extraction theoretical stage number is 2.01 stages, and the maximum flux of the extraction column is 4.8 m 3 / (m 2 ·hr).

[0041] Comparative Example 3

[0042] Keep other parameters the same as in Example 2, only change the orientation of the non-through groove, make the non-through groove face the stirring section, and the hole face the clarification section. Take the toluene-propanol-water system with high interfacial tension (interfacial tension is 32.4 mN / m) as the research object. Pump a toluene solution with a mass fraction of 10% of propanol into the light-phase inlet as the dispersed phase, and pump pure water into the heavy-phase inlet as the continuous phase. The solvent ratio is 1. When the rotation speed is 380 rpm and the total flow rate of the two phases is 60 mL / min, the extraction theoretical stage number is 1.58 stages, and the maximum flux of the extraction column is 5.5 m 3 / (m 2 ·hr).

[0043] The above-described embodiments only represent several implementation manners of the present invention. The description is relatively specific and detailed, but it should not be construed as a limitation on the scope of the patent of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several deformations and improvements can still be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the appended claims.

Claims

1. A stirred sieve plate extraction column, characterized in that It is alternately composed of a stirring section and a clarification section along the tower height direction, and sieve plates are provided at both ends of the stirring section; stepped holes are evenly formed in the sieve plate or a non-through groove is formed on one side of the sieve plate, and holes are evenly formed in the non-through groove; the large holes of the stepped holes face the clarification section, the small holes face the stirring section, the non-through groove faces the clarification section, and the evenly formed holes in the non-through groove face the stirring section.

2. The stirring sieve plate extraction column according to claim 1, characterized in that The large holes of the stepped holes have a diameter of 3-15 mm, the depth of the large holes is 50-95% of the sieve plate thickness, the small holes have a diameter of 2-4 mm, the depth of the small holes is 5-50% of the sieve plate thickness, and the opening ratio calculated by the small holes is 5-30%.

3. The stirring sieve plate extraction column according to claim 1, characterized in that The width of the non-through groove is 2-12 mm, the depth of the non-through groove is 50-95% of the sieve plate thickness, the diameter of the evenly formed holes in the non-through groove is 2-4 mm, the depth of the holes is 5-50% of the sieve plate thickness, and the opening ratio calculated by the holes is 5-30%.

4. The agitated sieve plate extraction column according to any one of claims 1-3, characterized in that The thickness of the sieve plate is 2-20 mm.

5. Application of the stirring sieve plate extraction tower according to any one of claims 1-3 in the extraction of a medium-high interfacial tension extraction system, wherein the medium-high interfacial tension extraction system refers to a system with an interfacial tension greater than or equal to 3 mN / m.

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