Filler-tower plate combined type multistage stirring continuous extraction tower and process

Abstract

The invention discloses a filler-tower plate composite multistage stirring continuous extraction tower and process, the tower comprises a cylindrical tower shell, the tower shell is provided with a heavy phase inlet, a light phase inlet, a light phase outlet and a heavy phase outlet, a motor mechanism is arranged above the tower shell, the motor mechanism is connected with a stirring shaft, the stirring shaft is vertically arranged in the tower shell, and the stirring shaft is connected with the tower shell. A plurality of tower plates are arranged in the tower shell at intervals from bottom to top, a plurality of riser tubes are arranged on the upper sides of the tower plates, a plurality of downcomers are arranged on the lower sides of the tower plates, and the plurality of riser tubes and the plurality of downcomers are arranged in a non-overlapping manner; fillers are respectively fixed on the upper side and the lower side of the tower plate; and a stirring paddle is arranged on the stirring shaft between every two tower plates. A plurality of layers of composite tower plates are arranged in the tower and play roles in fixing filler and collecting and redistributing liquid, a plurality of downcomers and riser tubes are distributed on the tower plates in an array manner, and a stirring paddle is mounted at the middle section of a stirring shaft between every two layers of tower plates. Through multiple times of stirring and layering, upward flowing of a light phase and downward flowing of a heavy phase are realized, and a multi-stage counter-current extraction effect is achieved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of liquid-liquid extraction equipment, and particularly relates to a packing-tray composite multi-stage stirring continuous extraction tower and a process. BACKGROUND

[0002] The extraction tower is a mass transfer equipment widely used in the chemical industry, petroleum refining, environmental protection and other industrial departments. The continuous stirring extraction tower has the advantages of large processing capacity, low energy consumption and stable operation, and is suitable for continuous production on an industrial scale. However, the axial back mixing is serious, which leads to a significant decrease in mass transfer efficiency when the device is scaled up. The packing extraction tower has the advantages of simple structure and easy manufacturing. The application of new packing can effectively improve the processing capacity and mass transfer efficiency of the extraction tower. The improved equipment such as the vibrating tray tower has problems such as dispersion phase coalescence, small effective contact area and high energy consumption.

[0003] Patent CN101693151A discloses an extraction tower with a tray, which adopts a "upper, middle and lower" sectional structure, and each layer is composed of "tray-wire mesh packing-tray". The stirring section is provided with stirring paddles, and the flow limiting effect of the tray is used to suppress axial back mixing. In the water-propyl alcohol-heptane system, the extraction efficiency is improved by 10-20%. However, this equipment is not suitable for high viscosity materials, and the mass transfer efficiency will also decrease when the device is scaled up. Patent CN116236816A discloses the application of a composite tray extraction tower in a low interfacial tension system. The two sides of the tray are made of hydrophilic and hydrophobic composite materials (stainless steel + polytetrafluoroethylene), and the dispersion phase "dispersion-coalescence-redispersion" cycle is realized through the difference in material wettability, solving the problems of easy emulsification and low flux in the low interfacial tension system. However, this equipment is only optimized for low interfacial tension systems, and the efficiency decreases for medium and high interfacial tension systems. Moreover, the processing of the composite tray is complex, and the hydrophilic and hydrophobic materials need to be precisely attached, which is costly. Patent CN202715271U discloses a tray extraction tower, in which the downcomer is installed obliquely, and is matched with parallel flow guide baffles, slotted structures and transverse small baffles, which significantly reduces the reflux area in the tower and makes the flow field close to ideal plug flow. However, the mass transfer area of this equipment only depends on the openings of the tray, and no packing is introduced for strengthening, so the mass transfer efficiency for high viscosity materials is limited. There is no stirring system, and the uniformity of the dispersed phase droplet size is poor. SUMMARY

[0004] In view of the above technical problems existing in the prior art, the purpose of the present application is to provide a new type of packing-tray composite multi-stage stirring continuous extraction tower with simple structure, large contact area, low axial back mixing and high mass transfer efficiency. Through the combined design of "composite tray + directional flow channel + adjustable speed stirring", the problems of high plate height and low processing capacity of traditional extraction towers and the like are solved, and continuous production can be realized. Compared with the existing patents, the present application has obvious advantages.

[0005] The technical scheme adopted by the present application is as follows:

[0006] The application discloses a filler-tray composite multistage stirring continuous extraction tower, which comprises a vertical cylindrical tower shell, a heavy phase inlet arranged at the upper part of the tower side wall of the tower shell, a light phase inlet arranged at the lower part of the tower side wall, a light phase outlet arranged at the top of the tower shell, a heavy phase outlet arranged at the bottom of the tower shell, a motor mechanism arranged above the tower shell, a stirring shaft connected with the motor mechanism, the stirring shaft vertically arranged in the tower shell, a plurality of tower plates arranged in the tower shell from bottom to top, a plurality of liquid lifting pipes arranged on the upper side of the tower plate and a plurality of liquid dropping pipes arranged on the lower side of the tower plate, the arrangement positions of the plurality of liquid lifting pipes and the plurality of liquid dropping pipes are not overlapped, and fillers are fixed on the upper side and the lower side of the tower plate respectively.

[0007] The tower shell is internally provided with a plurality of tower plates, which can fix the fillers and collect and redistribute the liquid.

[0008] Further, the diameter of the tower shell is 0.2-3 m, and the height is 2-50 m.

[0009] Further, the motor mechanism comprises a stirring motor and a speed reducer, both ends of the stirring shaft are penetrated to the outside of the tower shell and are connected with mechanical seals, a support is arranged above the tower shell, the stirring motor and the speed reducer are arranged on the support, and the stirring motor is connected with the upper end of the stirring shaft through the speed reducer.

[0010] Further, the rotating speed of the stirring motor is 1000-2800 rpm, the speed reducer is a hard tooth surface speed reducer or a belt pulley speed reducer, and the output rotating speed can be reduced to 50-500 rpm through a frequency conversion controller, gear adjustment and other modes.

[0011] Further, the tower plate is arranged in the axial direction of the tower shell and is 3-50 in number, and the distance between adjacent tower plates is 0.1-1.5 m.

[0012] Further, the tower plate is in a circular flat plate structure and has a thickness of 0.002-0.020 m, the fillers are symmetrically arranged on the upper and lower surfaces of the tower plate and have a height of 0.02-0.20 m, and the fillers are fixed on the tower plate through spot welding or steel wire binding.

[0013] Further, the fillers can be selected from structured packings such as 250Y, BX500 and CY700.

[0014] Further, different materials such as stainless steel, polytetrafluoroethylene, ceramic, titanium and polypropylene can be selected according to different extraction systems.

[0015] Further, the plurality of liquid lifting pipes and the plurality of liquid dropping pipes on the tower plate are arranged in annular arrays respectively, and the liquid lifting pipes are located at the periphery of the liquid dropping pipes.

[0016] Further, the center of the tray is also provided with a main downcomer, the main downcomer is a cylindrical hollow structure, the stirring shaft passes through the inside of the main downcomer of the tray; the ratio of the inner diameter of the main downcomer to the diameter of the stirring shaft is 1.1-2:1. The downcomers are uniformly arrayed in the periphery of the main downcomer.

[0017] Further, the aperture of the downcomer is 0.004-0.03 m, the opening rate of the downcomer on the tray is 1-20%, and the length of the downcomer is 0.01-0.2 m.

[0018] Further, the aperture of the downcomer is 0.004-0.03 m, the opening rate of the downcomer on the tray is 1-20%, and the length of the downcomer is 0.01-0.2 m.

[0019] Further, the stirring diameter of the stirring paddle is 0.25-0.9 times the inner diameter of the tower shell.

[0020] Further, 45° inclined blade paddles are selected for systems with small density difference, and flat blade paddles are selected for systems with large density difference.

[0021] Compared with the existing extraction tower, the present application has the following advantages:

[0022] (1) The present application combines the advantages of packed extraction tower and tray extraction tower, adopts the mode of combining packing and tray to form a tray, increases the mass transfer area compared with the traditional tray tower, and improves the renewal rate of liquid droplets; and the dispersed phase can be collected and redistributed multiple times, reducing the unevenness of radial concentration distribution;

[0023] (2) The downcomer and the riser are provided, the riser can provide an independent rising channel for the light phase, avoiding the problem that the two phases are difficult to separate after excessive mixing in the main tower area, and the riser (downcomer) can divide the space in the tower, guide the fluid to flow along the predetermined path, and reduce the axial backmixing;

[0024] (3) The size (diameter, height) of the riser can be designed according to the process requirements, so as to control the rising flow rate of the light phase, ensure that it has enough residence time in the tower to fully contact with the heavy phase, and improve the extraction efficiency. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 is a structural schematic view of the packed tray extraction tower of the present application;

[0026] Figure 2 is a structural schematic view of the tray of the present application;

[0027] Figure 3 is a top view of the upper part of the tray of the present application;

[0028] Figure 4 is a top view of the lower part of the tray of the present application.

[0029] Explanation of reference signs: agitator motor 1, support 2, heavy phase inlet 3, tray 4, riser 41, packing 42, downcomer 43, main downcomer 44, stirring paddle 5, tower body 6, light phase inlet 7, speed reducer 8, light phase outlet 9, stirring shaft 10, mechanical seal 11, heavy phase outlet 12. DETAILED DESCRIPTION

[0030] The application will be further described in conjunction with specific examples, but the scope of protection of the application is not limited thereto.

[0031] Example 1: Control Figures 1-4

[0032] A packing-tray combined multi-stage stirring continuous extraction column comprises a vertical cylindrical tower shell 6, a heavy phase inlet 3 is arranged on the upper part of the tower side wall of the tower shell 6, a light phase inlet 7 is arranged on the lower part of the tower side wall, a light phase outlet 9 is arranged on the top of the tower, and a heavy phase outlet 12 is arranged on the bottom of the tower.

[0033] Control Figure 1 The two ends of the stirring shaft 10 penetrate to the outside of the tower shell 6 and the mechanical seal 11 is arranged at the connection position of the two ends, the support 2 is arranged above the tower shell 6, the agitator motor 1 and the speed reducer 8 are arranged on the support 2, and the agitator motor 1 is connected with the upper end of the stirring shaft 10 through the speed reducer 8.

[0034] A plurality of trays 4 are arranged in the tower shell 6 from bottom to top, a plurality of risers 41 are arranged on the upper side of the tray 4, a plurality of downcomers 43 are arranged on the lower side of the tray 4, and the plurality of risers 41 and the plurality of downcomers 43 are arranged without overlapping. A main downcomer 44 is further arranged at the center of the tray 4, the main downcomer 44 is in a cylindrical hollow structure, and the stirring shaft 10 penetrates through the inside of the main downcomer 44 of the tray 4; the ratio of the inner diameter of the main downcomer 44 to the diameter of the stirring shaft 10 is 1.1-2:1.

[0035] Control Figures 2-4 The plurality of risers 41 and the plurality of downcomers 43 on the tray 4 are respectively arranged in an annular array, and the riser 41 is located at the periphery of the downcomer 43. The downcomer 43 is arranged at the periphery of the main downcomer 44.

[0036] The packing 42 is fixed on the upper side and the lower side of the tray 4, the packing 42 is symmetrically laid on the upper and lower surfaces of the tray 4, the height is 0.02-0.20 m, and the stirring paddle 5 is arranged on the stirring shaft 10 between every two trays 4.

[0037] The tower plate 4 is provided with a plurality of corresponding liquid lifting pipe holes and a plurality of corresponding liquid falling pipe holes according to the arrangement positions of the plurality of liquid lifting pipes 41 and the plurality of liquid falling pipes 43. Each liquid lifting pipe hole on the tower plate 4 is matched with a liquid lifting pipe 41, and the lower end of the liquid lifting pipe 41 is flush with the upper side surface of the tower plate 4. Each liquid falling pipe hole on the tower plate 4 is matched with a liquid falling pipe 43, and the lower end of the liquid falling pipe 43 is flush with the lower surface of the tower plate 4.

[0038] Principle and method of use of the present application:

[0039] The light phase enters the extraction tower from the light phase inlet 7 and flows upward under the action of buoyancy, is dispersed into small droplets by the stirring paddle 5 in the mixing zone, and becomes a dispersed phase; the heavy phase enters the upper part of the tower from the heavy phase inlet 3 and flows downward under the action of gravity, and generally serves as a continuous phase. In the mixing zone, the stirring paddle 5 also acts on the two phases, significantly increases the two-phase interface area, and can obtain a higher mass transfer rate. The dispersed two phases realize stratification in the regular channels of the packing 42, the light phase droplets that coalesce below the tower plate move upward, are redistributed by the liquid lifting pipe 41, and enter the stirring space of the stirring paddle 5 of the upper layer; the heavy phase above the tower plate moves downward, and the heavy phase enters the stirring space of the stirring paddle 5 of the lower layer through the liquid falling pipe 43. Finally, the light phase flows out from the light phase outlet 9 after stratification at the top of the tower, the heavy phase flows out from the heavy phase outlet 12, and the extraction process is completed.

[0040] Example 1: benzoic acid extraction (low viscosity, small density difference system)

[0041] Tower body parameters: the diameter of the tower shell is 0.2 m, the tower height is 2 m, the number of tower plates is 10, and the tower plate spacing is 0.18 m.

[0042] Material system: light phase: n-octane solution containing 0.38wt% benzoic acid (viscosity 0.7 mPa·s, density 703 kg / m 3 ); heavy phase: deionized water (viscosity 1.0 mPa·s, density 998 kg / m 3 );

[0043] Operating conditions: light phase flow rate: 0.51 m 3 / h (light phase inlet 7), heavy phase flow rate: 0.05 m 3 / h (heavy phase inlet 3).

[0044] Tower plate structure (see attached Figures 2-4 ):

[0045] Main liquid falling pipe 44: diameter 0.022 m, matched with stirring shaft diameter 0.015 m, gap 0.0035 m, pipe length 0.055 m;

[0046] Liquid falling pipe 43: number 32, single pipe diameter 0.005 m, opening rate on the tower plate 2%, single pipe length 0.05 m;

[0047] Riser 41: 32 in number, single tube diameter 0.005 m, hole opening rate on tray 2%, single tube length 0.05 m;

[0048] Control Figures 2-3 In the embodiment, the riser 41 and the downcomer 43 are respectively distributed along the annular array on the tray 4, the inner circle is the uniformly spaced downcomer 43, the outer circle is the uniformly spaced riser 41, and the arrangement positions of the downcomer 43 and the riser 41 are separated from each other and are not arranged in the same circle.

[0049] Filler 42: 250Y stainless steel corrugated structured filler is selected, and the single-side laying height is 0.05 m.

[0050] Agitation system: the agitation motor power is 2.0 kW, the agitation paddle 5 is a six straight-blade disc turbine paddle with a diameter of 0.14 m, and the agitation rotation speed is 300 rpm.

[0051] Control Example 1:

[0052] The control example 1 keeps the tower body parameters (diameter, height, tray number), the agitation conditions (rotation speed, paddle type), and the material system (flow, concentration, and viscosity) completely consistent with the original embodiment 1, and the only difference is that the arrangement positions of the multiple risers 41 and the multiple downcomers 43 on the tray 4 are overlapped.

[0053] That is, in the control example 1, the inner circle is the spaced staggered downcomer 43 and riser 41, and the outer circle is also the spaced staggered downcomer 43 and riser 41, and the arrangement positions of the downcomer 43 and the riser 41 are not separated from each other and are staggered in the same circle.

[0054] The extraction effect comparison of the embodiment 1 and the control example 1 is shown in Table 1.

[0055] Table 1

[0056]

[0057]

[0058] Embodiment 2: Acetic acid extraction (medium viscosity, medium density difference system)

[0059] Tower body parameters: the diameter of the tower shell is 0.2 m, the tower height is 2 m, the tray number is 10 layers, and the tray spacing is 0.18 m.

[0060] Material system: light phase: kerosene solution containing 5wt% acetic acid (viscosity 2.5 mPa·s, density 820 kg / m 3 ); heavy phase: 1 mol / L NaOH solution (viscosity 1.2 mPa·s, density 1020 kg / m3 ).

[0061] Operating conditions: Light phase flow rate: 0.1 m 3 / h (light phase inlet 7), heavy phase flow rate: 0.05 m 3 / h (heavy phase inlet 3).

[0062] Tray structure (see attached Figures 2-4 ) :

[0063] Main downcomer 44: diameter 0.022 m, fitted to stirring shaft diameter 0.015 m, gap 0.0035 m, tube length 0.05 m;

[0064] Downcomer 43: number 32, single tube diameter 0.005 m, opening rate on tray 2%, single tube length 0.05 m;

[0065] Lifting pipe 41: number 32, single tube diameter 0.005 m, opening rate on tray 2%, single tube length 0.05 m;

[0066] Filler 42: 250Y stainless steel corrugated regular filler selected, single side laying height 0.05 m.

[0067] Comparative Figures 2-3 In the comparative example 2, the lifting pipe 41 and the downcomer 43 are respectively distributed along the annular array on the tray 4, the inner circle is the uniformly spaced downcomer 43, the outer circle is the uniformly spaced lifting pipe 41, the arrangement positions of the downcomer 43 and the lifting pipe 41 are separated from each other, and are not arranged in the same circle.

[0068] Stirring system: stirring motor power 2.0 kW, stirring paddle 5 is a six straight-blade disc turbine paddle, diameter 0.14 m, stirring speed: 300 rpm.

[0069] Comparative example 2:

[0070] The comparative example 2 maintains the column body parameters (diameter, height, number of trays), stirring conditions (speed, paddle type), material system (flow rate, concentration, viscosity) completely consistent with the original example 2, and the only difference is that the arrangement positions of the plurality of lifting pipes 41 and the plurality of downcomers 43 on the tray 4 have overlap.

[0071] That is, in the comparative example 2, the inner circle is the spaced staggered downcomer 43 and lifting pipe 41, and the outer circle is also the spaced staggered downcomer 43 and lifting pipe 41, the arrangement positions of the downcomer 43 and the lifting pipe 41 are not separated from each other, and are staggered in the same circle.

[0072] The extraction effect comparison of example 2 and comparative example 2 is shown in table 2.

[0073] Table 2

[0074]

[0075] As can be seen from the experimental results in Table 1 and Table 2, the two phases of Examples 1-2 flow in order under the premise of radial partitioning, and there is almost no direct intersection. However, in the contrast examples 1-2, the downcomers 43 and the risers 41 are arranged alternately, and the inner ring simultaneously has a downcomer and a riser, which can cause the light phase to gather below the tray and mistakenly enter the adjacent downcomer, and then flow downward with the heavy phase to the lower tray, so that the light phase does not complete the mass transfer of the layer and flows backward, forming a light phase short circuit.

[0076] Meanwhile, in the examples 1-2, the risers and the downcomers are arranged in partitioning, which can effectively guide the fluid to flow along the predetermined path and reduce the axial mixing. In the contrast examples 1-2, the downcomers 43 and the risers 41 are arranged alternately, and the fluid path is more complex, the axial backmixing coefficient is increased, and the stage efficiency is reduced. It is concluded that the partitioning arrangement of the inner ring downcomer and the outer ring riser in the structure of the examples 1-2 has obvious advantages.

[0077] The content described in the specification is only a list of implementation forms of the inventive concept, and the protection scope of the present application should not be regarded as being limited to the specific forms stated in the examples.

Claims

1. A packed-plate composite multi-stage stirred continuous extraction tower, comprising a vertical cylindrical tower shell (6), wherein a heavy phase inlet (3) is provided on the upper part of the tower sidewall of the tower shell (6), a light phase inlet (7) is provided on the lower part of the tower sidewall, a light phase outlet (9) is provided at the top of the tower, and a heavy phase outlet (12) is provided at the bottom of the tower; a motor mechanism is provided above the tower shell (6), and a stirring shaft (10) is connected to the motor mechanism, the stirring shaft (10) being vertically arranged in the tower shell (6), characterized in that, Multiple trays (4) are arranged at intervals from bottom to top inside the tower shell (6). Multiple riser pipes (41) are arranged on the upper side of the tray (4) and multiple downcomer pipes (43) are arranged on the lower side. The arrangement of the multiple riser pipes (41) and the multiple downcomer pipes (43) does not overlap. Packing material (42) is fixed on the upper and lower sides of the tray (4). A stirring paddle (5) is installed on the stirring shaft (10) between each two trays (4).

2. The packed-plate composite multi-stage stirred continuous extraction tower as described in claim 1, characterized in that, The motor mechanism includes a stirring motor (1) and a reducer (8). The two ends of the stirring shaft (10) extend to the outside of the tower shell (6) and a mechanical seal (11) is provided at the connection between the two. A bracket (2) is provided above the tower shell (6). The stirring motor (1) and the reducer (8) are provided on the bracket (2). The stirring motor (1) is connected to the upper end of the stirring shaft (10) through the reducer (8).

3. The packed-plate composite multi-stage stirred continuous extraction tower as described in claim 1, characterized in that, The tower plate (4) is arranged in 3-50 pieces along the axial direction inside the tower shell (6), with a spacing of 0.1~1.5m between adjacent tower plates.

4. The packed-plate composite multi-stage stirred continuous extraction tower as described in claim 1, characterized in that, The tower plate (4) has a circular flat plate structure with a thickness of 0.002~0.020m; the packing (42) is symmetrically laid on the upper and lower surfaces of the tower plate (4) with a height of 0.02~0.20m, and is fixed on the tower plate (4) by spot welding or wire binding.

5. The packed-plate composite multi-stage stirred continuous extraction tower as described in claim 1, characterized in that, The packing (42) is selected from 250Y, BX500 or CY700 structured packing, and its material is stainless steel, polytetrafluoroethylene, ceramic, titanium metal or polypropylene.

6. The packed-plate composite multi-stage stirred continuous extraction tower as described in claim 1, characterized in that, Multiple riser pipes (41) and multiple downcomer pipes (43) on the tray (4) are distributed along a ring array, with the riser pipes (41) located on the periphery of the downcomer pipes (43).

7. The packed-plate composite multi-stage stirred continuous extraction tower as described in claim 1, characterized in that, A main downcomer (44) is also provided in the center of the tower plate (4). The main downcomer (44) has a cylindrical hollow structure. The stirring shaft (10) passes through the main downcomer (44) of the tower plate (4). The ratio of the inner diameter of the main downcomer (44) to the diameter of the stirring shaft (10) is 1.1~2:

1.

8. The packed-plate composite multi-stage stirred continuous extraction tower as described in claim 1, characterized in that, The downcomer (43) has a diameter of 0.004~0.03m, an opening ratio of 1~20% on the tray (4), and a length of 0.01~0.2m.

9. A packed-plate composite multi-stage stirred continuous extraction tower as described in claim 1, characterized in that, The riser pipe (41) has a diameter of 0.004~0.03m, an opening ratio of 1~20% on the tray (4), and a length of 0.01~0.2m.

10. The extraction process of a packed-plate composite multi-stage stirred continuous extraction tower as described in claim 1, characterized in that, The light phase enters the extraction tower from the light phase inlet (7) and flows upward under the action of buoyancy; The heavy phase enters the upper part of the column from the heavy phase inlet (3) and flows downward under the action of gravity; the light phase and the heavy phase are acted upon by the stirring paddle (5) in the column shell (6), which significantly increases the interphase area; the two phases after dispersion are stratified in the regular channel of the packing (42), the light phase below the tray moves upward and is redistributed through the riser pipe (41) and enters the stirring space of the upper stirring paddle (5); the heavy phase above the tray moves downward and enters the stirring space of the lower stirring paddle (5) through the downcomer pipe (43); finally, the light phase flows out from the light phase outlet (9) after stratification at the top of the column, and the heavy phase flows out from the heavy phase outlet (12), completing the extraction process.

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