High-flux continuous counter-current extractor

Abstract

The invention discloses a high-flux continuous counter-current extractor. The high-flux continuous counter-current extractor comprises an outer cylinder and a double-screw shaft, wherein the upper end of the outer cylinder is connected with the upper expansion section, and the lower end of the outer cylinder is connected with the lower expansion section; the double-screw shaft is coaxially and rotatably arranged in the outer cylinder, the double-screw shaft comprises an outer screw and an inner screw which are coaxially arranged, and a mixing annular gap is formed between the outer screw and the outer cylinder; the outer spiral is used for pushing the heavy phase to move downwards, and the inner spiral is used for pushing the light phase to move upwards. According to the invention, continuous counter-current extraction can still be realized without backmixing under the condition that the two-phase flux is obviously improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of extraction equipment, and particularly relates to a high-throughput continuous countercurrent extractor. Background Art

[0002] In industrial production such as chemical engineering, energy, and mining, operations for separating liquid mixtures are often involved. Among them, a liquid solvent (extraction agent) that is immiscible or partially miscible with the liquid mixture to be separated (mixed liquid) is added to form a two-phase system. The operation of separating the components by taking advantage of the distribution differences of each component in the two phases, where the easily soluble component (solute) enters the solvent phase (extraction phase) more, is called liquid-liquid extraction.

[0003] To improve the recovery efficiency of the target product and reduce equipment investment and maintenance costs, continuous countercurrent operation mode is often adopted in liquid-liquid extraction in industrial production, and the effect of multiple theoretical stages can be achieved in one device. However, due to the countercurrent flow of the two phases, the relative shear force between the phases is large, which makes the dispersed phase droplets easily entrained by the continuous phase and leads to backmixing. When the fluxes of the two phases are large and the droplets are small, the backmixing is more serious and eventually leads to flooding and abnormal operation.

[0004] There is already a high-throughput continuous countercurrent extraction column (patent number: ZL201610721385.X). The center of it is a rotating shaft with spiral channels on its surface. When the rotating shaft rotates, the spiral channels drive the light-phase droplets to move upward to offset the entrainment of the light-phase droplets by the downward movement of the heavy phase, so as to achieve continuous countercurrent extraction at a higher throughput. However, when the throughput is too large, flooding still occurs in this invention, which limits the application of this invention in engineering. Summary of the Invention

[0005] The present invention aims to solve at least one of the technical problems existing in the prior art. For this reason, an object of the present invention is to provide a high-throughput continuous countercurrent extractor, which can still achieve continuous countercurrent extraction without backmixing when the fluxes of the two phases are significantly increased.

[0006] The high-throughput continuous countercurrent extractor according to an embodiment of the present invention includes:

[0007] An outer cylinder, the upper end of the outer cylinder is connected to an upper enlarged section, and the lower end of the outer cylinder is connected to a lower enlarged section;

[0008] A double spiral shaft, the double spiral shaft is coaxially and rotatably arranged in the outer cylinder. The double spiral shaft includes an outer spiral and an inner spiral arranged coaxially. A mixing annulus is formed between the outer thread and the outer cylinder; the outer spiral is used to push the heavy phase downward, and the inner spiral is used to push the light phase upward.

[0009] The working principle of the high-throughput continuous countercurrent extractor according to the embodiments of the present invention is as follows: when the double spiral shaft rotates at a high speed, the outer spiral pushes the heavy phase downward, and the inner spiral pushes the light phase upward, thereby overcoming the flooding phenomenon caused by entrainment after the throughputs of the two phases are significantly increased. At the same time, when the outer spiral and the inner spiral rotate at a high speed, the light phase and the heavy phase flowing countercurrently in the mixing annulus are strongly agitated, thereby realizing efficient mixing and mass transfer.

[0010] Compared with the prior art, the beneficial effects of the high-throughput continuous countercurrent extractor according to the embodiments of the present invention are as follows: due to the adoption of the double spiral shaft, when the double spiral shaft rotates at a high speed, the outer spiral and the inner spiral can respectively push the heavy phase downward and the light phase upward, thereby overcoming the entrainment effect when the throughputs of the two phases are significantly increased, preventing the occurrence of flooding, and at the same time, the two phases flowing countercurrently can efficiently mix and mass transfer in the mixing annulus. The high-throughput continuous countercurrent extractor according to the embodiments of the present invention can be widely applied to the extraction of mixed liquids in fields such as chemical engineering, energy, and mining.

[0011] In some embodiments, the axes of the outer spiral and the inner spiral coincide.

[0012] In some embodiments, the outer cylinder is coaxially installed with the double spiral shaft.

[0013] In some embodiments, the heavy phase is fed from the bottom of the upper enlarged section close to the inner wall of the outer cylinder, and the light phase is fed from above the lower enlarged section close to the inside of the double spiral shaft.

[0014] In some embodiments, the inclination direction of the outer spiral is opposite to that of the inner spiral.

[0015] In some embodiments, the inner spiral is directly formed on the rotating main shaft, and the upper and lower ends of the rotating main shaft are respectively rotatably supported at the upper end of the upper enlarged section and the lower end of the lower enlarged section.

[0016] In some embodiments, the double spiral shaft further includes a fixed support module, the fixed support module is fixed on the rotating main shaft, and the outer spiral is fixed on the fixed support module.

[0017] In some embodiments, the fixed support module is in the shape of a cylindrical barrel, axial flow holes are provided at both the upper and lower ends of the fixed support module at intervals, and radial flow holes are provided at the circumferential side portion of the fixed support module at intervals.

[0018] In some embodiments, the fixed support module includes two fixed ends arranged at intervals up and down and a plurality of support bars located between the two fixed ends; each fixed end includes an annular part and a plurality of radiation bars, the plurality of radiation bars are circumferentially spaced apart, the radially outer ends of the plurality of radiation bars are fixed to the annular part, and the radially inner ends of the plurality of radiation bars are fixed to the rotating main shaft; the plurality of support bars are circumferentially spaced apart, and the upper and lower ends of the plurality of support bars are respectively fixed to the two fixed ends; the outer helix is fixed to the plurality of support bars.

[0019] In some embodiments, when the double helix shaft rotates at a high speed, the outer helix pushes the heavy phase downward, and the inner helix pushes the light phase upward, and the double helix shaft enables the light phase and the heavy phase flowing in a countercurrent manner in the mixing annulus to be efficiently mixed and mass-transferred.

[0020] Additional aspects and advantages of the present invention will be given in part in the following description, will become apparent in part from the following description, or will be learned through the practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The above and / or additional aspects and advantages of the present invention will become apparent and be readily understood from the following description of the embodiments in conjunction with the accompanying drawings, in which:

[0022] Figure 1 is a schematic structural diagram of a high-throughput continuous countercurrent extractor according to an embodiment of the present invention;

[0023] Figure 2 is a schematic cross-sectional view of a double helix shaft of a high-throughput continuous countercurrent extractor according to an embodiment of the present invention;

[0024] Figure 3 is a front view of a double helix shaft of a high-throughput continuous countercurrent extractor according to an embodiment of the present invention;

[0025] Figure 4 is a partially enlarged three-dimensional schematic view of a double helix shaft of a high-throughput continuous countercurrent extractor according to an embodiment of the present invention;

[0026] Figure 5 is a schematic diagram of the working principle of a high-throughput continuous countercurrent extractor according to an embodiment of the present invention.

[0027] Reference numerals:

[0028] Outer cylinder 1; upper enlarged section 2; lower enlarged section 3; double spiral shaft 4; rotating main shaft 400; outer spiral 401; inner spiral 402; fixed support module 403; axial flow hole 4031; radial flow hole 4032; fixed end 4033; ring part 4033a; radiation bar 4033b; support bar 4034; upper bearing assembly 5; lower bearing assembly 6; light phase overflow port 7; heavy phase distributor 8; heavy phase feed port 9; mixing annulus 10; light phase feed pipe 11; light phase distributor 12; heavy phase discharge port 13; heavy phase drain pump 14; heavy phase feed pump 15; light phase feed pump 16. Detailed implementation mode

[0029] The embodiments of the present invention will be described in detail below. Examples of the embodiments are shown in the drawings, where the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by referring to the drawings are exemplary and are only used to explain the present invention and should not be construed as a limitation of the present invention.

[0030] The following combines Figures 1 to 5 to describe the high-throughput continuous countercurrent extractor of the embodiments of the present invention.

[0031] As Figures 1 to 5 shown, the high-throughput continuous countercurrent extractor according to the embodiments of the present invention includes an outer cylinder 1 and a double spiral shaft 4. Among them, the upper end of the outer cylinder 1 is connected to the upper enlarged section 2, and the lower end of the outer cylinder 1 is connected to the lower enlarged section 3; the double spiral shaft 4 is coaxially and rotatably arranged in the outer cylinder 1, and the double spiral shaft 4 includes an outer spiral 401 and an inner spiral 402 arranged coaxially. A mixing annulus 10 is formed between the outer thread and the outer cylinder 1; the outer spiral 401 is used to push the heavy phase downward, and the inner spiral 402 is used to push the light phase upward.

[0032] The working principle of the high-throughput continuous countercurrent extractor of the embodiments of the present invention is as follows: when the double spiral shaft 4 rotates at a high speed, the outer spiral 401 pushes the heavy phase downward, and the inner spiral 402 pushes the light phase upward, so as to overcome the flooding phenomenon caused by entrainment after the throughputs of the two phases are significantly increased. At the same time, when the outer spiral 401 and the inner spiral 402 rotate at a high speed, the light phase and the heavy phase flowing countercurrently in the mixing annulus 10 are strongly stirred, thereby realizing efficient mixing and mass transfer.

[0033] Compared with the prior art, the beneficial effects of the high-throughput continuous countercurrent extractor of the embodiments of the present invention are: due to the adoption of the double spiral shaft 4, when the double spiral shaft 4 rotates at a high speed, the outer spiral 401 and the inner spiral 402 can respectively push the heavy phase downward and the light phase upward, so as to overcome the entrainment effect when the throughputs of the two phases are significantly increased, prevent flooding from occurring, and at the same time, the two phases flowing countercurrently can efficiently mix and mass transfer in the mixing annulus 10. The present invention can be widely applied to the extraction of mixed liquids in the fields of chemical industry, energy, and mining.

[0034] In some embodiments, the axes of the outer helix 401 and the inner helix 402 coincide. The reason for the coaxial arrangement of the outer helix 401 and the inner helix 402 is that the outer helix 401 and the inner helix 402 can share a rotating shaft, such as the rotating main shaft 400 below. While the rotating main shaft 400 rotates, it is necessary for the outer helix 401 to drive the heavy phase downward and the inner helix 402 to drive the light phase upward, so they are arranged coaxially.

[0035] In some embodiments, the outer cylinder 1 is coaxially installed with the double helix shaft 4. In this way, when the double helix shaft 4 rotates at a high speed, the outer helix 401 and the inner helix 402 can respectively push the heavy phase downward and the light phase upward, so as to better overcome the entrainment effect when the fluxes of the two phases increase significantly, better prevent flooding from occurring, and at the same time, the two countercurrently flowing phases can be efficiently mixed and mass transferred in the mixing annulus 10.

[0036] In some embodiments, the heavy phase is fed from the bottom of the upper enlarged section 2 close to the inner wall of the outer cylinder 1, and the light phase is fed from above the lower enlarged section 3 close to the inside of the double helix shaft 4. When the double helix shaft 4 starts to rotate, due to the centrifugal force, the heavy phase (i.e., the liquid with a large density) will be on the outside of the outer cylinder 1 and the light phase, i.e., the liquid with a small density, will be on the inside of the outer cylinder 1. Therefore, the heavy phase is fed from near the outside and the light phase is fed from near the inside, which is consistent with the action of the centrifugal force field on the liquid.

[0037] In some embodiments, the inclination directions of the outer helix 401 and the inner helix 402 are opposite to each other. In this way, when the double helix shaft 4 rotates at a high speed, the inclined helical surface of the outer helix 401 pushes the heavy phase downward, and the inclined helical surface of the inner helix 402 does the opposite, pushing the light phase upward, so as to overcome the flooding phenomenon caused by entrainment after the fluxes of the two phases increase significantly. At the same time, when the outer helix 401 and the inner helix 402 rotate at a high speed, the light and heavy phases flowing countercurrently in the mixing annulus 10 are strongly stirred, thus realizing efficient mixing and mass transfer.

[0038] In some embodiments, the inner helix 402 is directly formed on the rotating main shaft 400, and the upper and lower ends of the rotating main shaft 400 are respectively rotatably supported at the upper end of the upper enlarged section 2 and the lower end of the lower enlarged section 3. Thereby, the inner helix 402 is convenient for processing and manufacturing and is also convenient for installation.

[0039] Specifically, the upper end of the rotating main shaft 400 is connected to the upper end of the upper enlarged section 2 through the upper bearing assembly 5, and the lower end of the rotating main shaft 400 is connected to the lower end of the lower enlarged section 3 through the lower bearing assembly 6, so as to realize that the rotating main shaft 400 is rotatably supported at the upper end of the upper enlarged section 2 and the lower end of the lower enlarged section 3.

[0040] In some embodiments, the double - helix shaft 4 further includes a fixed - support module 403. The fixed - support module 403 is fixed on the rotating main shaft 400, and the outer helix 401 is fixed on the fixed - support module 403. By providing the fixed - support module 403, it is convenient to fix the outer helix 401 on the rotating main shaft 400, and the fixation is reliable.

[0041] In some embodiments, the fixed - support module 403 is in the shape of a cylindrical barrel. Axial flow holes 4031 are provided at both the upper end and the lower end of the fixed - support module 403 at intervals, and radial flow holes 4032 are provided at intervals on the circumferential side of the fixed - support module 403. In this way, when the double - helix shaft 4 rotates at a high speed, the heavy phase affected by the outer helix 401 and the light phase affected by the inner helix 402 can be dispersed and efficiently mixed for mass transfer.

[0042] In some embodiments, the fixed - support module 403 includes two fixed ends 4033 arranged at intervals up and down and a plurality of support bars 4034 located between the two fixed ends 4033; each fixed end 4033 includes an annular part 4033a and a plurality of radial bars 4033b. The plurality of radial bars 4033b are circumferentially spaced apart to form axial flow holes 4031 between adjacent radial bars 4033b. The radially outer ends of the plurality of radial bars 4033b are fixed to the annular part 4033a, and the radially inner ends of the plurality of radial bars 4033b are fixed to the rotating main shaft 400; the plurality of support bars 4034 are circumferentially spaced apart to form radial flow holes 4032 between adjacent support bars 4034. The upper end and the lower end of the plurality of support bars 4034 are respectively fixed to the two fixed ends 4033; the outer helix 401 is fixed on the plurality of support bars 4034. This fixed - support module 403 has a reliable structure, is convenient to process, and when the double - helix shaft 4 rotates at a high speed, the heavy phase affected by the outer helix 401 and the light phase affected by the inner helix 402 can be dispersed and efficiently mixed for mass transfer.

[0043] In some embodiments, when the double - helix shaft 4 rotates at a high speed, the outer helix 401 pushes the heavy phase downward, and the inner helix 402 pushes the light phase upward. The double - helix shaft 4 enables the light phase and the heavy phase flowing in a counter - current manner in the mixing annulus 10 to be efficiently mixed for mass transfer.

[0044] The extraction experiment of a specific example of the high - throughput continuous counter - current extractor according to the embodiments of the present invention is described below.

[0045] An extraction experiment is carried out using 30% TBP - kerosene as the light phase (dispersed phase, extractant) and 3.0 mol / L HNO3 aqueous solution as the heavy phase (continuous phase, feed solution).

[0046] As Figure 5 shown, it is used to extract nitric acid from the aqueous feed solution.

[0047] The heavy-phase feed pump 15 pumps the aqueous nitric acid solution, i.e., the heavy phase (refer to arrow A in Figure 5 ), into the heavy-phase distributor 8 through the heavy-phase feed port 9. The aqueous nitric acid solution flows downward under the action of gravity and enters the upper part of the mixing annulus 10 close to the inner wall of the outer cylinder 1. The lower expansion section 3, the mixing annulus 10, and the upper expansion section 2 are filled with the heavy phase, which is called the column filling operation. After the column filling operation is completed, the motor is started to make the double-helix shaft 4 rotate at a high speed of 300 revolutions per minute, and at the same time, the heavy-phase drain pump 14 connected to the heavy-phase discharge port 13 is started. The 30% TBP-kerosene solution, i.e., the light phase (refer to arrow O in Figure 5 ), enters the light-phase distributor 12 through the light-phase feed pump 16 through the light-phase feed port 11. Due to the density difference between the light phase and the heavy phase, the light phase spontaneously rises upward and closely adheres to the inner side of the double-helix shaft 4 and enters the lower part of the mixing annulus 10 to contact the outer helix 401 and the inner helix 402, and is sheared into dispersed-phase droplets. Under the action of the centrifugal force field generated by the double-helix shaft 4, the lighter light-phase (dispersed phase) droplets move upward closer to the inner surface of the double-helix shaft 4, while the heavier heavy phase (continuous phase) tends to move downward farther away from the double-helix shaft 4 and closer to the outer surface of the outer cylinder 1. The outer helix 401 on the double-helix shaft 4 helps the heavy phase overcome the entrainment effect caused by the increase in the two-phase shear force and drag force when the flux is significantly increased, and pushes the heavy phase downward, while the inner helix 402 also helps the light phase overcome the entrainment effect caused by the significant increase in the flux and pushes the light phase upward. Thus, the high-flux continuous countercurrent extractor can still ensure normal continuous countercurrent operation without flooding when the fluxes of the two phases are significantly increased. At the same time, the high-speed rotation of the double-helix shaft 4 generates a strong turbulent stirring effect on the light phase and the heavy phase in the mixing annulus 10, and even Taylor vortices are generated, significantly enhancing the mass transfer rate between the two phases. In the experiment, the heavy-phase feed pump 15 and the light-phase feed pump 16 are controlled to ensure that the feeding rates of the two phases are both 30 L / h, and the post-extraction heavy-phase drain pump 14 is controlled to discharge the post-extraction heavy phase (refer to arrow R in Figure 5 ) to make the heavy-phase inlet and outlet rates balanced; while the post-extraction light phase (refer to arrow E in Figure 5 ) is discharged from the light-phase overflow port 7. Experiments show that: when the feeding rates of the two phases of the high-flux continuous countercurrent extraction column (patent number ZL2016 1 0721385.X) are about 10 L / h, flooding has already occurred and continuous countercurrent extraction cannot be carried out, while in the high-flux continuous countercurrent extractor of the embodiment of the present invention, the feeding rates of the two phases can reach 30 L / h and still operate normally, and the nitric acid extraction efficiency can reach about 90%.

[0048] In the description of this specification, the descriptions referring to terms such as "one embodiment", "some embodiments", "schematic embodiments", "examples", "specific examples", or "some examples", etc. mean that the specific features, structures, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples.

[0049] Although the embodiments of the present invention have been shown and described, those of ordinary skill in the art can understand that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention, and the scope of the present invention is defined by the claims and their equivalents.

Claims

1. A high-throughput continuous countercurrent extractor, characterized in that: include: An outer cylinder, wherein the upper end of the outer cylinder is connected to the upper enlarged section, and the lower end of the outer cylinder is connected to the lower enlarged section; A double helix shaft is coaxially and rotatably arranged in the outer cylinder, and the double helix shaft includes an outer helix and an inner helix coaxially arranged, and a mixing annular gap is formed between the outer thread and the outer cylinder; the outer helix is ​​used to push the heavy phase downward, and the inner helix is ​​used to push the light phase upward.

2. The high-throughput continuous countercurrent extractor according to claim 1, characterized in that: The axis of the outer helix coincides with the axis of the inner helix.

3. The high-throughput continuous countercurrent extractor according to claim 1, characterized in that: The outer cylinder is coaxially mounted with the double helical shaft.

4. The high-throughput continuous countercurrent extractor according to claim 1, characterized in that: The heavy phase is fed from the bottom of the upper expansion section close to the inner wall of the outer cylinder, and the light phase is fed from the top of the lower expansion section close to the inner side of the double screw shaft.

5. The high-throughput continuous countercurrent extractor according to claim 1, characterized in that: The inclination direction of the outer spiral and the inclination direction of the inner spiral are opposite to each other.

6. The high-throughput continuous countercurrent extractor according to claim 5, characterized in that: The inner spiral is directly formed on the rotating main shaft, and the upper end and the lower end of the rotating main shaft are rotatably supported at the upper end of the upper enlarged section and the lower end of the lower enlarged section respectively.

7. The high-throughput continuous countercurrent extractor according to claim 6, characterized in that: The double helix shaft further comprises a fixed support module, wherein the fixed support module is fixed on the rotating main shaft, and the outer helix is ​​fixed on the fixed support module.

8. The high-throughput continuous countercurrent extractor according to claim 7, characterized in that: The fixed support module is cylindrical, and the upper and lower ends of the fixed support module are both provided with axial flow holes distributed at intervals, and the circumferential side of the fixed support module is provided with radial flow holes distributed at intervals.

9. The high-throughput continuous countercurrent extractor according to claim 8, characterized in that: The fixed support module includes two fixed end portions spaced apart in an upper and lower direction and a plurality of support strips located between the two fixed end portions; each of the fixed end portions includes a circular ring portion and a plurality of radial strips, the plurality of radial strips are spaced apart in the circumferential direction, the radial outer ends of the plurality of radial strips are fixed to the circular ring portion, and the radial inner ends of the plurality of radial strips are fixed to the rotating main shaft; the plurality of support strips are spaced apart in the circumferential direction, and the upper ends and lower ends of the plurality of support strips are respectively fixed to the two fixed end portions; the outer spiral is fixed on the plurality of support strips.

10. The high-throughput continuous countercurrent extractor according to any one of claims 1 to 9, characterized in that: When the double helix shaft rotates at high speed, the outer helix pushes the heavy phase downward, and the inner helix pushes the light phase upward. The double helix shaft enables the light phase and the heavy phase flowing in countercurrent in the mixing annulus to be efficiently mixed and transferred.

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