Venturi type micro-droplet generation device and micro-droplet generation method thereof

Abstract

The invention discloses a Venturi type micro-droplet generation device and a micro-droplet generation method thereof, and relates to the technical field of liquid-liquid heterogeneous reaction devices. The device comprises a venturi tube and a feeding tube, the venturi tube is used for conveying a first liquid phase, the venturi tube is internally provided with a venturi flow channel of a cavity structure, the venturi flow channel is divided into a contraction section, a throat pipe and an expansion section which are sequentially communicated, a feeding port is formed in the side wall of the throat pipe, a partition plate is arranged in the throat pipe, the height of the partition plate is equal to the length of the throat pipe, and the feeding port is communicated with the venturi flow channel. The interior of the throat pipe is divided into a plurality of flowing cavities by the partition plates, and each flowing cavity is communicated with the feeding hole; the feeding pipe is used for conveying a second liquid phase, and the feeding pipe is communicated with the flowing cavity through the feeding opening, so that the first liquid phase and the second liquid phase collide with each other in the flowing cavity and are sheared to generate micro-droplets. The partition plates are arranged to divide the throat pipe into a plurality of flowing cavities, and the turbulence and shearing degree in the throat pipe is improved by fully utilizing the wall surface effect.

Description

Technical Field

[0001] The present invention relates to the technical field of liquid-liquid heterogeneous reaction devices, and in particular to a Venturi-type micro-droplet generating device and a micro-droplet generating method thereof. Background Art

[0002] Liquid-liquid heterogeneous reactions are a common reaction system in chemical production processes, such as oxidation, esterification, nitration, sulfonation, halogenation, alkylation and other reactions in organic chemicals, as well as emulsion polymerization in polymer chemicals. In industrial production, about 85% of liquid-liquid mixing / reaction processes are completed in tank reactors. Due to the immiscibility of liquids and the easy stratification, tank reactors consume a lot of energy, and the droplets generated by mechanical stirring are relatively large. 32 Between 100 and 2000 μm, even in many large-scale liquid-liquid heterogeneous reactors, a thicker light phase layer forms at the top of the reactor due to limited stirring power consumption, a typical example being the fermentation of long-chain dibasic acids. Recent research has also shown that nano-micro droplets can produce a certain amount of ozone, which can promote the progress of oxidation reactions. Therefore, the miniaturization of droplets not only accelerates liquid-liquid mass transfer but also produces many unexpected effects. To disperse the liquid phase involved in the reaction into droplets of the smallest possible size and enhance the liquid-liquid mass transfer process, researchers have developed process intensification reactors such as static mixers, microreactors, and rotating packed beds.

[0003] For example, the invention patent with authorization publication number CN 106861480 B proposes a static mixer comprising: a housing; and a hollow mixing unit, which is disposed within the housing and connected to the outside through an inlet at one end. The hollow mixing unit is a hollow structure made of sintered powder and has micropores on its surface. A mixing channel is formed between the hollow mixing unit and the housing. This device can separate the dispersed phase into bubbles, droplets, or jets before mixing with the dispersed phase, greatly improving mixing efficiency. However, this type of mixer has a complex structure, increasing fluid resistance and production costs. Furthermore, high-density difference systems are prone to stratification within the housing, making uniform mixing difficult to achieve.

[0004] The invention patent with authorization publication number CN 109985588 B proposes a microchannel reactor comprising a droplet generation zone, a droplet intra-fluid convection mixing zone, and a droplet pre-crosslinking and curing zone. The channels in the droplet intra-fluid convection mixing zone include linear channels and non-linear channels, which may be S-shaped, Z-shaped, or other irregularly shaped curved channels. The channel width of the droplet generation zone is 50-500 microns, and the channel width of the droplet intra-fluid convection mixing zone is 100-1000 microns. The microspheres produced using the microchannel reactor provided by this invention have advantages such as controllable particle size, uniform particle size, and good sphericity. However, due to the small size of the microchannels, the fluid flow is characterized by a low Reynolds number and high surface tension, resulting in weak convection and diffusion, and the problem of easy clogging (especially in reactive crystallization systems). In addition, the internal structure is too complex, making mass production difficult. Industrial scale-up can only be achieved through "quantity scale-up", which is not suitable for industrial chemical production with high output requirements.

[0005] Patent application CN 117797752 A proposes an intrinsically safe rotating packed bed for enhanced liquid-liquid contact and its applications. This device uses a high-speed liquid jet within a driving chamber to power the impeller. A coaxial structure transmits the rotational speed, effectively dispersing the liquid phase in the rotating packed bed packing, enhancing the liquid-liquid contact process. This type of reactor can produce droplets as small as 10-150μm, but it contains rotating components that require sealing. Furthermore, the liquid can be unevenly distributed within the packing, and clogging is a common problem in systems containing solids.

[0006] As can be seen from the above, the aforementioned novel microdroplet generators are not suitable for large-scale industrial applications due to their complex internal components, high production difficulty, and clogging susceptibility. Furthermore, the microdroplets they generate are relatively large (mostly larger than 10 μm), which still limits their ability to improve liquid-liquid two-phase mass transfer. Therefore, it is necessary to develop a novel microdroplet generator that can simply and energy-efficiently produce droplets smaller than 10 μm in large quantities. Summary of the Invention

[0007] The purpose of the present invention is to overcome the shortcomings of the existing technology and provide a Venturi-type micro-droplet large-scale generation device. By innovating the structure of the traditional Venturi tube, it breaks the current technical status quo that it is only applied to the gas-liquid two-phase field and creates a new application in the field of liquid-liquid two-phase reaction.

[0008] Specifically, the present invention divides the throat into multiple flow cavities to obtain a flow channel with a high surface area to volume ratio. The strong wall effect forms a high shear rate zone between the first liquid phase, the second liquid phase and the wall, thereby dispersing the two phases into micron-sized droplets, solving the problems of complex internal components, high energy consumption, small processing capacity, easy clogging and large droplet size in the micro-droplet generating device in the prior art.

[0009] In one aspect of the present application, a Venturi-type micro-droplet generating device is provided, comprising:

[0010] A venturi tube, the venturi tube being used to convey the first liquid phase, the interior of the venturi tube being a venturi flow channel with a cavity structure, the venturi flow channel being divided into a contraction section, a throat pipe, and an expansion section that are sequentially connected, a feed port being provided on a side wall of the throat pipe, a partition plate being provided inside the throat pipe, the height of the partition plate being equal to the length of the throat pipe, the partition plate dividing the interior of the throat pipe into a plurality of flow chambers, each of the flow chambers being connected to the feed port;

[0011] A feed pipe is used to transport the second liquid phase. The feed pipe is connected to the flow chamber through the feed port, so that the first liquid phase and the second liquid phase collide and shear in the flow chamber to generate micro droplets.

[0012] The present application divides the interior of the throat into several flow chambers by providing a partition plate in the throat. Due to the presence of the partition plate, when the first liquid phase enters the throat from the throat inlet, it collides with one end of the partition plate to realize the diversion of the first liquid phase. The first liquid phase enters different flow chambers respectively, and the second liquid phase enters the throat through the feed port and directly collides with the partition plate, making full use of the wall effect of the flow chamber to preliminarily crush the second liquid phase and produce some smaller droplets. At this time, the first liquid phase and the second liquid phase are mixed in the flow chamber formed by the partition plate to obtain a mixed phase containing microdroplets. Under the state of high-speed flow of the first liquid phase, the mixed phase is driven into the expansion section. As the inner diameter of the expansion section becomes larger, the flow rate gradually decreases, and the pressure gradually increases, a strong shear force will be generated near the wall of the expansion section. The mixed phase is broken for the second time under the strong shear action generated by the wall effect, thereby generating smaller microdroplets. At the same time, the microdroplets generated in the throat will also be broken again to obtain even smaller microdroplets.

[0013] Optionally, the partition plate is a straight plate or a cross plate, the height of the partition plate is equal to the length of the throat pipe, and the width of the partition plate is equal to the inner diameter of the throat pipe.

[0014] The partition plate diverts the first liquid phase and preliminarily crushes the second liquid phase. By setting the height of the partition plate equal to the length of the throat, the wall area per unit volume of the second liquid phase can be increased, and the inflowing second liquid phase can be preliminarily crushed. By setting the length of the partition plate equal to the inner diameter of the throat, the second liquid phase can be mixed with the first liquid phase, and the high-speed flow power of the first liquid phase can be efficiently utilized to strongly shear the second liquid phase to form smaller droplets.

[0015] Optionally, the partition plate includes a first tube plate, a second tube plate and several tube bundles, the first tube plate is located at the inlet of the throat pipe, and several first liquid phase inlets are provided on the first tube plate, the second tube plate is located at the outlet of the throat pipe, and several micro-droplet outlets corresponding to the first liquid phase inlets are provided on the second tube plate; the tube bundle is arranged between the first liquid phase inlet and the micro-droplet outlet, and each tube bundle is provided with a second liquid phase inlet.

[0016] The first tube sheet splits the first liquid phase through the first liquid phase inlet, which then enters different tube bundles. This splitting enhances the impact of the first liquid phase, allowing for better mixing with the second liquid phase and exerting a certain shearing and crushing effect on the second liquid phase. The second liquid phase enters the liquid storage space formed by the first and second tube sheets, the outer wall of the tube bundle, and the sidewall of the throat pipe through the feed port, and then enters the flow chamber through the second liquid phase inlet on the tube bundle. The first liquid phase flows at high speed in the flow chamber and mixes with the second liquid phase that enters the flow chamber through the second liquid phase inlet to form a mixed phase containing microdroplets. Driven by the first liquid phase, the mixed phase enters the expansion section, where it is further broken down by strong shear forces, resulting in small and uniform microdroplets.

[0017] Specifically, the tube bundle is a round tube.

[0018] Optionally, the ratio of the diameter of the first liquid phase inlet to the diameter of the first tube sheet is less than 1 / 2, and the ratio of the diameter of the micro-droplet outlet to the diameter of the second tube sheet is less than 1 / 2.

[0019] When the diameter of the first liquid phase inlet is 1 / 2 of the diameter of the first tube sheet, two parallel first liquid phase inlets can be set to split the first liquid phase into two beams, thereby increasing the impact force of the first liquid phase; when the diameter of the first liquid phase inlet is 1 / 4 of the diameter of the first tube sheet, seven first liquid phase inlets can be set to be evenly distributed on the first tube sheet, thereby splitting the first liquid phase into seven beams, thereby further increasing the impact force of the first liquid phase.

[0020] Preferably, the diameter of the first liquid phase inlet is equal to the diameter of the micro-droplet outlet.

[0021] Optionally, there are at least two second liquid phase inlets, which are evenly arranged along the side wall of the tube bundle.

[0022] When two second liquid phase inlets are set, the second liquid phase can be promoted to enter the flow chamber quickly, and a large number of micro-droplets below 10 microns can be obtained in combination with the flow speed of the first liquid phase; when the second liquid phase inlets are set to less than two, due to the reduction in the number of second liquid phase inlets, the second liquid phase entering the flow chamber at the same time will be reduced, and the first liquid phase will still maintain a high flow rate, which will cause part of the first liquid phase to be unable to fully mix with the second liquid phase, and the quality of the obtained micro-droplets will be different.

[0023] Optionally, the vertical distance between the feed port and the throat inlet is A, the vertical distance between the second liquid phase inlet and the feed port is D, and A:D=1:(0.5-1).

[0024] When the second liquid phase inlet is set corresponding to the feed port, part of the second liquid phase directly enters the flow cavity through the feed port and mixes with the first liquid phase, and the remaining part falls into a certain liquid storage space formed between the first tube sheet, the second tube sheet, the outer wall of the tube bundle and the side wall of the throat pipe; when the second liquid phase inlet is not set corresponding to the feed port, the second liquid phase first enters the liquid storage space for buffering, and then evenly enters the flow cavity through the second liquid phase inlet.

[0025] Preferably, the second liquid phase inlet is a circular inlet and a strip-shaped inlet, the diameter of the circular inlet is 1-3 mm, the width of the strip-shaped inlet is 1-2 mm, and the height is 4-6 mm.

[0026] The second liquid phase inlet is set as a circular inlet and a strip inlet to increase the speed of the second liquid phase entering the flow chamber, effectively ensure the rapid and uniform entry of the second liquid phase, ensure the effective mixing of the first liquid phase and the second liquid phase, and obtain micro-droplets with good uniformity and stability.

[0027] Optionally, there are at least two feed ports, each of which is arranged on a side close to the inlet of the throat pipe, and all of the feed ports are arranged on the same horizontal plane.

[0028] The feed port is arranged on the side of the inlet close to the throat pipe, so that the first liquid phase and the second liquid phase can be better mixed in the throat pipe, laying the foundation for the second liquid phase to enter the expansion section for secondary shearing to obtain micro-droplets with more uniform quality, and can effectively improve the mixing degree of the first liquid phase and the second liquid phase.

[0029] Optionally, the distance between the feed port and the throat pipe inlet is A, the distance between the feed port and the throat pipe outlet is B, and A≤B.

[0030] When the feed port is set in the middle of the throat, A and B are equal, and the spatial length of the mixing of the second liquid phase and the first liquid phase in the flow chamber is half the length of the throat; when the feed port is set near the throat inlet, A<B, and the spatial length of the mixing of the second liquid phase and the first liquid phase in the flow chamber is greater than half the length of the throat. The increase in the mixing length improves the mixing effect of the first liquid phase and the second liquid phase.

[0031] Preferably, A:B=1:(4-7).

[0032] Optionally, the feed port is arranged on the side wall of the throat pipe corresponding to the angle bisector of the flow cavity.

[0033] This arrangement can maximize the wall area of ​​the second liquid phase in contact with the flow chamber, thereby preliminarily breaking up the second liquid phase to the greatest extent.

[0034] Optionally, a transition chamber is further provided inside the Venturi tube, and the transition chamber is provided between the feed pipe and the Venturi flow channel for buffering the second liquid phase.

[0035] Setting up a transition chamber can make the second liquid phase entering the flow chamber more stable. The second liquid phase enters the transition chamber from the feed pipe for buffering. The fluid pressure in the transition chamber is relatively constant. The liquid in the transition chamber can evenly enter the throat pipe through the feed port and mix more evenly with the first liquid phase, producing micro-droplets with higher size uniformity under the action of the wall effect.

[0036] Preferably, the vertical distance between the height position of the feed pipe and the feed port is C, and the vertical distance between the feed port and the throat entrance is A, C:A=1:(1-3).

[0037] When the positions of the feed pipe and the feed port are set correspondingly, C=0. At this time, part of the flowing liquid of the second liquid phase can directly enter the flow chamber through the feed port set corresponding to the feed pipe, and the remaining part will fall into the transition chamber; when the positions of the feed pipe and the feed port are not set correspondingly, such as C:A=1, the second liquid phase will first enter the transition chamber for buffering, and then the second liquid phase will enter the flow chamber at a stable flow rate to mix with the first liquid phase.

[0038] Optionally, the cross-section of the throat is circular, and the inner diameter of the throat is 1 / 5-1 / 4 of the inner diameter of the inlet of the contraction section or the outlet of the expansion section.

[0039] Under this setting, the impact force of the first liquid phase when entering the throat in the contraction section is enhanced, which can effectively increase the flow rate of the first liquid phase in the throat. At the same time, it can also enhance the wall effect of the expansion section, strengthen the dispersion force of the mixed phase, and form micro-droplets of uniform size.

[0040] Optionally, the cross-section of the throat is a special-shaped circle, and the special-shaped circle includes a rectangle and arcs arranged on both sides of the rectangle.

[0041] Under this setting, the movement distance of the second liquid phase from the feed port to the impact on the partition plate is shortened, and the wall effect is fully utilized to enhance the turbulence intensity of the second liquid phase at the throat to enhance the crushing effect, preventing the second liquid phase from entering the throat from the feed port and flowing directly upward along the inner wall of the throat to the expansion section. This setting can improve the effect of the initial crushing of the second liquid phase at the throat.

[0042] Optionally, the inner diameters of the inlet of the contraction section and the outlet of the expansion section are equal.

[0043] Under this setting, the structural design of the Venturi tube is simpler and more symmetrical, which not only makes the manufacturing process easier, but also makes installation and maintenance more convenient.

[0044] Optionally, the length of the throat is 1 / 6-1 / 5 of the total length of the Venturi tube.

[0045] Under this setting, in cooperation with the partition plate, the first liquid phase can be effectively promoted to have a relatively stable flow state in the throat pipe, and can better withstand the pressure and impact force of the fluid.

[0046] Optionally, the Venturi-type micro-droplet generating device is produced by 3D printing, and the material of the Venturi-type micro-droplet generating device is selected from at least one of resin and 316L stainless steel.

[0047] Another aspect of the present application provides a method for generating micro-droplets, which is performed using the Venturi-type micro-droplet generating device according to any of the above items, comprising the steps of:

[0048] The first liquid phase is transported into the venturi tube through the inlet of the contraction section, and the second liquid phase is transported into the flow cavity through the feed pipe, wherein the volume fraction of the second liquid phase accounts for less than 20% of the total volume of the first liquid phase and the second liquid phase.

[0049] Under this ratio, the first liquid phase and the second liquid phase can be mixed more evenly, the size of the obtained microdroplets can be smaller, the uniformity and stability can be higher, and the number and scale of the produced microdroplets can also be considerable.

[0050] Optionally, the flow rate of the first liquid phase at the throat inlet is set to 5-20 m / s. This flow rate setting can promote mixing of the first liquid phase and the second liquid phase, allowing the reaction to achieve the desired effect in a shorter time, improving mixing efficiency, and thus improving the uniformity of the droplet size; while avoiding excessively high flow rates that may cause droplet merging or breakage, reducing mixing uniformity, and further reducing droplet stability during the generation and mixing process.

[0051] The above technical solution has the following beneficial effects:

[0052] 1. The present invention sets a partition plate in the throat pipe to divide the inside of the throat pipe into multiple separate flow chambers, which can divert the first liquid phase and increase the flow rate of the first liquid phase in each flow chamber. At the same time, the second liquid phase can be preliminarily crushed. The second liquid phase enters from the feed port and directly collides with the partition plate, making full use of the wall effect of the flow chamber to perform the initial crushing of the second liquid phase, thereby enhancing the crushing effect of the second liquid phase.

[0053] 2. The present invention is provided with a transition chamber, which can make the second liquid phase entering the flow chamber more stable. The second liquid phase enters the transition chamber from the feed pipe for buffering. The fluid pressure in the transition chamber is relatively constant. The liquid in the transition chamber can enter the throat pipe evenly through the feed port and mix more evenly with the first liquid phase. Under the action of the wall effect, micro-droplets with higher uniformity of size are produced.

[0054] 3. The microdroplets produced by the present invention are in the 1-10 μm range. Compared to the most widely used kettle reactors for liquid-liquid reactions (typically >150 μm), the microdroplet generation device of the present invention consumes less energy and produces smaller and more uniform microdroplets, exponentially increasing the liquid-liquid mass transfer rate. Compared to new process-intensified liquid-liquid two-phase reactors, the present invention has a simpler structure. Furthermore, due to the high-speed flow of the first liquid phase within the Venturi flow channel, it is less susceptible to clogging during reactions involving solids, such as reactive crystallization.

[0055] 4. The volume ratio of the first liquid phase in the present invention can reach 20%, the production and processing capacity of microdroplets is large, and the device in the present invention can produce microdroplets on a large scale and in large quantities. The microdroplets produced are small in size and uniform. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] The disclosure of the present invention will become more easily understood with reference to the accompanying drawings, which are for illustrative purposes only and are not intended to limit the scope of protection of the present invention.

[0057] Figure 1 A cross-sectional view of the Venturi micro-droplet generating device provided in Example 1 of the present invention;

[0058] Figure 2 A top view of the Venturi micro-droplet generating device provided in Example 1 of the present invention;

[0059] Figure 3 A cross-sectional view of a Venturi micro-droplet generating device provided in Example 2 of the present invention;

[0060] Figure 4 A top view of the Venturi micro-droplet generating device provided in Example 2 of the present invention;

[0061] Figure 5 A cross-sectional view of a Venturi micro-droplet generating device provided in Example 3 of the present invention;

[0062] Figure 6 A three-dimensional diagram of a partition plate in a Venturi micro-droplet generating device provided in Example 4 of the present invention;

[0063] Figure 7 This is the micro-droplet image generated in Example 3 of the present invention;

[0064] Figure 8 This is the micro-droplet image generated in Comparative Example 1 of the present invention.

[0065] 1. Venturi tube; 11. Contraction section; 12. Throat; 13. Expansion section; 2. Feed pipe; 3. Feed port; 4. Partition plate; 41. First tube sheet; 411. First liquid phase inlet; 42. Tube bundle; 43. Second tube sheet; 44. Second liquid phase inlet; 441. Circular inlet; 442. Strip inlet; 5. Flow chamber; 6. Transition chamber. DETAILED DESCRIPTION

[0066] The following further describes the specific embodiments of the present invention with reference to the accompanying drawings and examples. Identical components are denoted by the same reference numerals. It should be noted that the terms "front," "rear," "left," "right," "up," and "down" used in the following description refer to directions in the accompanying drawings, and the terms "inward" and "outward" refer to directions toward and away from the geometric center of a particular component, respectively.

[0067] Unless otherwise specified, the methods used in the examples and comparative examples of the present application are conventional methods in the prior art.

[0068] Example 1

[0069] The Venturi droplet generating device used in this embodiment is made of transparent photosensitive resin and is produced by 3D printing. Its cross-sectional view and top view are shown in FIG. Figure 1 and Figure 2shown. The device includes a venturi tube 1 and a feed pipe 2. The interior of the venturi tube 1 is a venturi flow channel with a cavity structure, which is provided with a contraction section 11, a throat pipe 12 and an expansion section 13 in sequence. The outlet of the contraction section 11 is connected to the inlet of the throat pipe 12, and the outlet of the throat pipe 12 is connected to the inlet of the expansion section 13. A "cross-shaped" partition plate 4 is provided inside the throat pipe 12. The height of the partition plate 4 is equal to the length of the throat pipe 12, and the width is equal to the inner diameter of the throat pipe 12, dividing the interior of the throat pipe 12 into four flow chambers 5. Four feed ports 3 are provided at 90° intervals on the side of the throat pipe 12 close to the contraction section 11. The inner diameter of the four feed ports 3 is 4 mm. The centers of the feed ports 3 are located at the same height and on the angle bisector of each flow chamber 5. The distance between the feed port 3 and the inlet of the throat pipe 12 is A, and the distance between the feed port 3 and the outlet of the throat pipe 12 is B. In this embodiment, A:B=1:4. Each feed port 3 is connected to a feed pipe 2, and the feed pipe 2 is arranged perpendicular to the throat pipe 12.

[0070] In this embodiment, the total length of the venturi tube 1 is 120 mm, the length of the throat 1 is 1 / 5 of the length of the venturi tube 1 , and the ratio of the length of the contraction section 11 to the expansion section 13 is 1:2.

[0071] In this embodiment, the inner diameters of the inlet of the contraction section 11 and the outlet of the expansion section 13 are equal, both being 40 mm.

[0072] In this embodiment, the cross section of the throat pipe 12 is circular, and its inner diameter is 1 / 4 of the inner diameter of the inlet of the contraction section 11 .

[0073] This example uses water as the first liquid phase and kerosene as the second liquid phase. The venturi tube 1 is positioned vertically, with the outlet of the expansion section 13 facing upward. Water is pumped into the venturi tube 1 from the inlet of the contraction section 11, and kerosene is pumped into the flow chamber 5 from the feed pipe 1. The water-to-kerosene flow ratio is 8:2, and the water velocity at the inlet of the throat pipe 12 is 7 m / s.

[0074] As water flows upward along the Venturi channel, its cross-sectional area decreases as the channel narrows, reducing it to 1 / 16 of the cross-sectional area at the entrance of throat 12. Consequently, the water velocity at throat 12 increases dramatically. A "cross-shaped" partition plate 4 divides throat 12 into four independent flow chambers 5, increasing the internal wall area of ​​throat 12 to 2.3 times that of a conventional circular throat 12. After kerosene enters the flow chambers 5 of throat 12 from feed inlet 3, it is initially impacted by the cross-shaped partition plate 4, causing initial fragmentation. After the high-speed water flow in throat 12 enters diverging section 13, the widening of the channel causes a gradual decrease in flow velocity and an increase in pressure. This generates strong shear forces near the walls of diverging section 13, causing secondary fragmentation of the kerosene and water, resulting in smaller droplets.

[0075] Example 2

[0076] The Venturi droplet generating device used in this embodiment is 3D printed and made of 316L stainless steel. Its exterior is cylindrical. Its cross-sectional view and top view are shown in FIG. Figure 3 and Figure 4 The device includes a venturi tube 1 and a feed pipe 2. The feed pipe 2 is connected to the outer wall of the venturi tube 1. The interior of the venturi tube 1 is a venturi flow channel with a cavity structure. It is sequentially provided with a contraction section 11, a throat pipe 12 and an expansion section 13. The outlet of the contraction section 11 is connected to the inlet of the throat pipe 12, and the outlet of the throat pipe 12 is connected to the inlet of the expansion section 13. A "straight" partition plate 4 is provided inside the throat pipe 12. The height of the partition plate 4 is equal to the length of the throat pipe 12, and the width of the partition plate 4 is equal to the inner diameter of the throat pipe 12. The interior of 12 is equally divided into two flow chambers 5. Two feed ports 3 are set at an interval of 180° on the side of the throat pipe 12 close to the contraction section 11. The inner diameter is 4 mm. The centers of the two feed ports 3 are located at the same height and are located in the middle position of one side of each flow chamber 5. The distance between the feed port 3 and the inlet of the throat pipe 12 is A, and the distance between the feed port 3 and the outlet of the throat pipe 12 is B. In this embodiment, A:B=1:7. Each feed port 3 is connected to a feed pipe 2, and the feed pipe 2 is arranged perpendicular to the throat pipe 12.

[0077] In this embodiment, the total length of the venturi tube 1 is 100 mm, the length of the throat 12 is 1 / 6 of the length of the venturi tube 1 , and the ratio of the length of the contraction section 11 to the expansion section 13 is 1:2.

[0078] In this embodiment, the inner diameters of the inlet of the contraction section 11 and the outlet of the expansion section 13 are equal, both being 35 mm.

[0079] Specifically, in this embodiment, the throat 12 has a circular cross-section with an inner diameter of 7 mm. The wall near the feed inlet 3 is rectangular rather than curved, and the distance between the two symmetrical rectangular sidewalls of the throat 12 is 3 / 5 of its inner diameter. This design aims to shorten the distance the second liquid phase travels from the feed inlet 3 to the partition plate 4, fully utilizing the wall effect to enhance the turbulence intensity of the second liquid phase in the throat 12, thereby enhancing the crushing effect. This prevents the second liquid phase from entering the throat 12 from the feed inlet 3 and then immediately flowing upward along the inner wall of the throat 12 to the expansion section 13, thereby preventing it from being fully crushed in the throat 12.

[0080] This example used liquid paraffin oil as the first liquid phase and a supersaturated potassium sulfate solution as the second liquid phase. Venturi tube 1 was positioned vertically upward, with the outlet of expansion section 13 facing upward. A pump delivered the liquid paraffin oil from the inlet of contraction section 11 into Venturi tube 1, and a pump delivered the supersaturated potassium sulfate solution from feed pipe 2 into flow chamber 5. This simulated a liquid-liquid heterogeneous reaction crystallization process. The flow ratio of the liquid paraffin oil to the supersaturated potassium sulfate solution was 19:1, and the flow velocity of the liquid paraffin oil at the inlet of throat pipe 12 was 10.7 m / s.

[0081] After the supersaturated potassium sulfate solution enters the flow chamber 5 within the throat 12 from the feed inlet 3, it first impacts the "I"-shaped partition 4 due to the obstruction of the partition 4, causing initial fragmentation. This disrupts its supersaturation and initiates crystallization. The crystal-containing supersaturated potassium sulfate solution then enters the expansion section 13, where the wall effect causes secondary fragmentation, generating smaller droplets for further crystallization. Due to the high-speed flow of the first liquid phase, liquid paraffin oil, within the Venturi channel, virtually no crystals remain after the reaction, and no clogging occurs.

[0082] Example 3

[0083] This embodiment also uses 3D printing to generate a Venturi-type micro-droplet generating device, and its cross-sectional view is as follows: Figure 5 As shown, its exterior is also cylindrical. The difference between the device used in this embodiment and that used in Example 2 is that the feed pipe 2 is not directly connected to the feed port 3. Instead, a transition chamber 6 is provided between the feed pipe 2 and the Venturi channel. The vertical distance between the height of the feed pipe 2 and the feed port 3 is C, and the distance between the feed port 3 and the entrance of the throat pipe 12 is A. In this embodiment, C:A is set to 1:3. The second liquid phase first enters the transition chamber 6 from the feed pipe 2 for buffering. Because the fluid pressure in the transition chamber 6 is relatively constant, the second liquid phase in the transition chamber 6 can evenly enter the throat pipe 12 through the feed port 3, generating micro-droplets with relatively uniform size.

[0084] In this embodiment, water is used as the first liquid phase and kerosene is used as the second liquid phase for the experiment. The volume fraction of kerosene accounts for 3% of the total volume of the water-kerosene two-phase. The flow rate of water at the throat 12 is 13.5 m / s.

[0085] When the solution of this embodiment is adopted and C:A=1:1, the same technical effect can be achieved.

[0086] Example 4

[0087] One difference between this embodiment and embodiment 3 is that the throat pipe 12 in this embodiment is a round tube rather than a special-shaped round tube. Another difference is that the partition plate 4 in this embodiment is a honeycomb type, comprising a first tube sheet 41, a second tube sheet 43 and a tube bundle 42. The tube bundle 42 has the same length as the throat pipe 12. The first tube sheet 41 is located at the inlet of the throat pipe 12. The first tube sheet 41 is provided with a plurality of first liquid phase inlets 411. The second tube sheet 43 is located at the outlet of the throat pipe 12. The second tube sheet 43 is provided with a plurality of micro-droplet outlets (not shown in the figure) corresponding to the first liquid phase inlets 411. Seven tube bundles 42 are provided between the first liquid phase inlet 411 and the micro-droplet outlet. Each tube bundle 42 is provided with a second liquid phase inlet 44. The arrangement is as follows: Figure 6 As shown, the interior of the throat pipe 12 is divided into seven circular tubular flow chambers 5 by the honeycomb-shaped partition plate 4. In this embodiment, the inner diameter of the throat pipe 12 is 12 mm, and the inner diameter of the circular tube is 3 mm. The wall area inside the throat pipe 12 is 1.75 times that of the traditional Venturi tube 1.

[0088] The vertical distance between the feed port 3 and the entrance of the throat pipe 12 is A, and the vertical distance between the second liquid phase inlet 411 and the feed port 3 is D. In this embodiment, A:D=1:0.5. Eight feed ports 3 are opened at 45° intervals on the side wall of the throat pipe 12. Two circular inlets 441 with a diameter of 1 mm and two 1 mm × 5 mm strip inlets 442 are opened on the side wall of each circular tube. The circular inlets 441 and the strip inlets 442 are arranged at 90° intervals. After the second liquid phase enters the throat pipe 12 from the feed port 3, it is absorbed by the outer wall of the tube bundle 42. The second liquid phase is blocked and remains in a certain liquid storage space formed between the first tube sheet 41, the second tube sheet 43, the outer wall of the tube bundle 42 and the side wall of the throat pipe 12, and enters the circular tubular flow cavity 5 through the circular inlet 441 and the strip inlet 442 on the tube bundle 42. The first liquid phase flows at a high speed in each circular tubular flow cavity 5, making full use of the wall shear effect of the circular tubular flow cavity 5 to preliminarily break up the second liquid phase, and then moves to the expansion section 13 for further breakage to obtain uniform and stable micro-droplets.

[0089] In this embodiment, water is used as the first liquid phase and kerosene is used as the second liquid phase for the experiment. The volume fraction of kerosene accounts for 3% of the total volume of the water-kerosene two phases. The flow rate of water at the throat 12 is 20 m / s.

[0090] When the solution of this embodiment is adopted and the ratio of A:D is set to 1:1, the same technical effect can be achieved.

[0091] Example 5

[0092] The difference between this embodiment and embodiment 2 is that the cross section of the throat pipe 12 of this comparative example is a perfect circle, and the other parameters are the same.

[0093] Example 6

[0094] The difference between this embodiment and embodiment 2 is that the flow rate of the liquid paraffin oil at the inlet of the throat pipe 12 is 25 m / s, and the other parameters are the same.

[0095] Example 7

[0096] The difference between this embodiment and embodiment 2 is that the flow rate of the liquid paraffin oil at the inlet of the throat pipe 12 is 3 m / s, and the other parameters are the same.

[0097] Comparative Example 1

[0098] The difference between this comparative example and Example 1 is that the partition plate 4 is not provided in the throat pipe 12 of this comparative example, and the other parameters are the same as those of Example 1.

[0099] The droplet size of the micro-droplet samples produced in the above examples and comparative examples was measured by a laser particle size analyzer, and the d 10 and d 90 The statistical results are shown in Table 1 below. Figure 7 This is the micro-droplet image generated by Example 3 of the present invention. Figure 8 These are images of micro-droplets generated in Comparative Example 1 of the present invention. From the above two figures, it can be seen that the micro-droplets generated in this application are smaller and more uniform in size.

[0100] Table 1

[0101] serial number <![CDATA[Droplet diameter d 50 / μm]]> <![CDATA[Difference in droplet diameters d 10 and d 90 / μm]]> Example 1 9.38 15.24 Example 2 5.47 8.06 Example 3 4.19 7.74 Example 4 0.78 2.88 Example 5 23.94 34.59 Example 6 16.52 30.18 Example 7 20.60 26.23 Comparative Example 1 81.48 137.56

[0102] As can be seen from the above table, the Venturi-type micro-droplet generating device provided by the present invention can generate 10 μm (d 50 ) below, and the smallest can be as small as 0.78μm. By comparing Example 1 with Comparative Example 1, it can be found that after the throat 12 is divided into multiple flow chambers 5 by a partition plate 4, the wall effect of the flow chamber 5 can reduce the diameter of the generated droplets from 81.48μm to 9.38μm; by comparing the data of Example 2 and Example 5, it can be found that the present invention changes the throat 12 from a traditional round tube to a special-shaped round tube, shortens the distance the second liquid phase moves from the feed port 3 to the partition plate 4, and makes most of the second liquid phase enter the throat 12 and collide and break with the partition plate 4 before flowing to the expansion section 13 for secondary breakage, so that the size of the generated droplets can be reduced by more than 77%.

[0103] As can be seen from Examples 6 and 7, when the flow rate of the first liquid phase in the throat 12 is too high or too low, it is not conducive to the generation of micro-droplets with smaller diameters. This is because when the flow rate is too high, the fluid generates strong turbulence in the venturi tube 1, which easily leads to droplet coalescence. When the flow rate is too low, the velocity gradient near the wall surface of the flow chamber 5 decreases, reducing the initial fragmentation effect on the second liquid phase. At the same time, the low flow rate of the first liquid phase reduces the force that drives the mixed phase into the expansion section, which in turn reduces the secondary fragmentation effect and the resulting micro-droplets have lower uniformity.

[0104] As needed, the above technical solutions can be combined to achieve the best technical effect.

[0105] The foregoing is merely an embodiment of the present application, and the scope of protection of the present application is not limited by these specific embodiments, but is determined by the claims of the present application. For those skilled in the art, the present application may have various modifications and variations. Any modifications, equivalent substitutions, improvements, etc. made within the technical ideas and principles of the present application should be included in the scope of protection of the present application.

Claims

1. A Venturi-type micro-droplet generating device, comprising: A venturi tube, the venturi tube being used to convey the first liquid phase, the interior of the venturi tube being a venturi flow channel with a cavity structure, the venturi flow channel being divided into a contraction section, a throat pipe, and an expansion section that are sequentially connected, a feed port being provided on a side wall of the throat pipe, a partition plate being provided inside the throat pipe, the height of the partition plate being equal to the length of the throat pipe, the width of the partition plate being equal to the inner diameter of the throat pipe, the partition plate dividing the interior of the throat pipe into a plurality of flow chambers, each of the flow chambers being connected to the feed port; A feed pipe is used to transport the second liquid phase. The feed pipe is connected to the flow chamber through the feed port, so that the first liquid phase and the second liquid phase collide and shear in the flow chamber to generate micro droplets.

2. A Venturi-type micro-droplet generating device according to claim 1, characterized in that: The partition plate is a straight plate or a cross plate; or The partition plate includes a first tube plate, a second tube plate and several tube bundles. The first tube plate is located at the inlet of the throat pipe and is provided with several first liquid phase inlets. The second tube plate is located at the outlet of the throat pipe and is provided with several micro-droplet outlets corresponding to the first liquid phase inlets. The tube bundle is arranged between the first liquid phase inlet and the micro-droplet outlet, and each tube bundle is provided with a second liquid phase inlet.

3. A Venturi-type micro-droplet generating device according to claim 2, characterized in that: The ratio of the diameter of the first liquid phase inlet to the diameter of the first tube sheet is less than 1 / 2, and the ratio of the diameter of the micro-droplet outlet to the diameter of the second tube sheet is less than 1 / 2; Preferably, the diameter of the first liquid phase inlet is equal to the diameter of the micro-droplet outlet.

4. A Venturi-type micro-droplet generating device according to claim 2, characterized in that: There are at least two second liquid phase inlets, which are evenly arranged along the side wall of the tube bundle; The vertical distance between the feed port and the throat inlet is A, the vertical distance between the second liquid phase inlet and the feed port is D, A:D=1:(0.5-1); Preferably, the second liquid phase inlet is two circular inlets and two strip-shaped inlets, the diameter of the circular inlet is 1-3 mm, the width of the strip-shaped inlet is 1-2 mm, and the height is 4-6 mm.

5. A Venturi-type micro-droplet generating device according to any one of claims 1 to 4, characterized in that: There are at least two feed ports, each of which is arranged on a side close to the inlet of the throat pipe, and all of the feed ports are arranged on the same horizontal plane; The distance between the feed port and the throat inlet is A, and the distance between the feed port and the throat outlet is B, A≤B. Preferably, A:B=1:(4-7); The feed port is arranged on the side wall of the throat pipe corresponding to the angular bisector of the flow cavity.

6. A Venturi-type micro-droplet generating device according to any one of claims 1 to 4, characterized in that: The venturi tube is further provided with a transition chamber, which is provided between the feed pipe and the venturi channel and is used to buffer the second liquid phase; Preferably, the vertical distance between the height position of the feed pipe and the feed port is C, the distance between the feed port and the throat entrance is A, and C:A=1:(1-3).

7. A Venturi-type micro-droplet generating device according to any one of claims 1 to 4, characterized in that: The cross section of the throat is circular, and the inner diameter of the throat is 1 / 5-1 / 4 of the inner diameter of the inlet of the contraction section or the outlet of the expansion section; or The cross section of the throat is a special-shaped circle, and the special-shaped circle includes a rectangle and arcs arranged on both sides of the rectangle.

8. A Venturi-type micro-droplet generating device according to any one of claims 1 to 4, characterized in that: The inlet of the contraction section and the outlet of the expansion section have the same inner diameter; and / or The length of the throat is 1 / 6-1 / 5 of the total length of the venturi tube.

9. A method for generating microdroplets, characterized in that: The method is carried out using the Venturi-type micro-droplet generating device according to any one of claims 1 to 8, comprising the steps of: The first liquid phase is transported into the venturi tube through the inlet of the contraction section, and the second liquid phase is transported into the flow cavity through the feed pipe, wherein the volume fraction of the second liquid phase accounts for less than 20% of the total volume of the first liquid phase and the second liquid phase.

10. The method for generating microdroplets according to claim 9, characterized in that: The flow rate of the first liquid phase in the throat is set to 5-20 m / s.

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