Ultrasonic microcavity reactor and use method thereof

Abstract

The invention provides an ultrasonic microcavity reactor which comprises a reactor main body and an ultrasonic wave generating device, and the reactor main body is installed in an ultrasonic wave radiating surface of the ultrasonic wave generating device; at least one micro-cavity unit is arranged in the reactor main body, the micro-cavity unit is of a hollow pipeline structure extending in the horizontal axial direction, and the inner diameter of a cavity of the micro-cavity unit sequentially comprises an axial divergent section with the cross section area continuously increasing from the inlet end of the axial divergent section to the outlet end of the axial divergent section in the fluid flowing direction; and the axial gradually-shrinking section is positioned at the downstream of the axial gradually-expanding section, and the cross sectional area of the axial gradually-shrinking section is continuously reduced from the inlet end of the axial gradually-shrinking section to the outlet end of the axial gradually-shrinking section. The micro-cavity unit is designed into a rotational flow cavity which is gradually expanded and gradually shrunk in the axial direction; therefore, a hurricane type cavitation bubble group can be formed in the reaction cavity of the ultrasonic microcavity reactor. Compared with a conventional ultrasonic cavitation reactor, hurricane type cavitation bubbles can be generated, the sound field distribution is concentrated, the shearing capacity is high, and the mixing and emulsifying effects are good.

Description

Technical Field

[0001] This invention relates to the field of chemical reaction apparatus technology, and more particularly to an ultrasonic microcavity reactor and its method of use. Background Technology

[0002] Ultrasound, as a highly efficient form of energy transfer, induces cavitation when propagating in liquid media, which is the core basis for its widespread application in the chemical industry. When ultrasound passes through a liquid, the molecules in the medium vibrate violently under the alternating pressure of the sound waves, forming countless tiny cavitation bubbles. These bubbles, in the instant of expansion, contraction, and collapse, create an extreme microenvironment with high temperature (up to thousands of Kelvin) and high pressure (up to hundreds of atmospheres), accompanied by strong shock waves and high-speed microjets. This unique physicochemical effect can efficiently disrupt intermolecular forces and enhance mass and heat transfer processes. Therefore, it is widely used in many chemical unit operations such as emulsification, solvent extraction, degradation of organic pollutants, and synthesis of nanomaterials, becoming a key technology for improving reaction efficiency and optimizing product performance.

[0003] However, most mainstream ultrasonic reactors in the current industry adopt traditional straight-tube or batch-type structures. Their design concepts fail to fully adapt to the characteristics of cavitation effects, resulting in limited energy utilization efficiency and process performance. In particular, in straight-tube ultrasonic reactors, the generation and distribution of cavitation bubbles in the internal flow field exhibit significant segregation. Within the confined space, they appear as dispersed filamentous forms or vortex-entrained states near the tube wall, failing to cover the central region of the flow field. This distribution pattern directly leads to a series of performance shortcomings: First, the low probability and weak interaction between cavitation bubbles and emulsion droplets result in poor shearing and fragmentation effects, failing to effectively refine droplet size; second, poor mixing uniformity, with cavitation bubbles easily adhering to and forming on the wall surface, creating "dead zones" of cavitation bubble scarcity in large-sized reactors, ultimately resulting in a wide particle size distribution in the produced emulsion or nanoparticles, characterized by a high PDI (polydispersity index) value, making it difficult to meet the uniformity and consistency requirements of high-end applications; more critically, the wide particle size distribution significantly accelerates the Ostwald ripening process—smaller droplets, due to their higher solubility, gradually dissolve, and their components migrate to larger droplets, further widening the droplet size difference, ultimately causing emulsion stratification and demulsification, severely compromising the long-term stability of the product.

[0004] Against the backdrop of increasingly stringent requirements for product refinement and high stability in the chemical industry, the structural defects of traditional ultrasonic reactors have become a core bottleneck restricting their application expansion. Therefore, developing a novel reactor structure capable of actively controlling the spatial distribution of cavitation bubbles, achieving efficient energy distribution within the microreactor, altering the sound field distribution and the secondary Bjerknes force between bubbles, and thus overcoming the limitations of existing technologies in emulsification uniformity, particle size control precision, and product stability, has become a critical technological need urgently needing to be addressed in the field of ultrasonic chemistry, possessing significant theoretical value and promising industrial application prospects. Summary of the Invention

[0005] The purpose of this invention is to provide an ultrasonic microcavity reactor and its usage method to solve the technical problems existing in the background art.

[0006] The technical solution adopted by the present invention is as follows: an ultrasonic microcavity reactor, comprising a reactor body and an ultrasonic wave generating device, wherein the reactor body is installed in the ultrasonic wave radiating surface of the ultrasonic wave generating device; the reactor body is provided with at least one microcavity unit, wherein the microcavity unit is a hollow pipe structure extending along a horizontal axis, and the inner diameter of the cavity of the microcavity unit includes, in sequence along the fluid flow direction: an axially expanding section, the cross-sectional area of ​​which continuously increases from the inlet end of the axially expanding section to the outlet end of the axially expanding section; and an axially contracting section, located downstream of the axially expanding section, the cross-sectional area of ​​which continuously decreases from the inlet end of the axially contracting section to the outlet end of the axially contracting section.

[0007] More preferably, the aforementioned axially expanding segment and the axially contracting segment are symmetrically distributed.

[0008] More preferably, the inner diameter of the cavity of the microcavity unit changes smoothly and continuously along the horizontal axis, forming a unique maximum cross-section at the midpoint between the axially expanding section and the axially contracting section.

[0009] More preferably, the microcavity unit has a microcavity diameter D = 2-9 mm; a microcavity length L = 5-20 mm; a diameter-to-lateral ratio L / D = 1.0-5.0; an axial tapering angle θ = 20-80°; and an axial tapering arc transition radius R = 2-20 mm.

[0010] More preferably, the reactor body contains multiple microcavity units connected in series, with a spacing S = 5-20 mm between adjacent microcavity units.

[0011] More preferably, each of the above-mentioned multiple microcavity units connected in series has the same size.

[0012] More preferably, the frequency range of the ultrasonic generator is 10kHz-100kHz, and the power density is 1-10W / mL.

[0013] More preferably, the material of the microcavity unit is quartz glass, titanium alloy or stainless steel.

[0014] Based on the same technical concept, the present invention also provides a method for using the ultrasonic microcavity reactor as described above, wherein when using the ultrasonic microcavity reactor, the control parameter P is... u t R D h 1 / 2 / (ρQ²) is in the range of 200-20000, where P u For ultrasonic power density, t R Let ρ be the residence time, ρ be the fluid density, Q be the total flow rate, and D be the total flow rate. h It is the hydraulic diameter.

[0015] More preferably, when preparing nanoemulsions using the ultrasonic microcavity reactor, a coarse emulsion, a two-phase or multiphase fluid is introduced into the microcavity unit of the ultrasonic microcavity reactor.

[0016] Compared with existing technologies, the beneficial effects of this invention are as follows: By optimizing the design of the reaction chamber structure of the ultrasonic microcavity reactor, the microcavity unit in the ultrasonic microcavity reactor is designed as an axially expanding-contracting swirling cavity; this enables the formation of hurricane-shaped cavitation bubble clusters within the reaction chamber of the ultrasonic microcavity reactor. Compared with conventional ultrasonic cavitation reactors, the hurricane-shaped cavitation bubbles generated by this invention have a concentrated sound field distribution, strong shearing ability, and good mixing and emulsification effects. The resulting emulsion or nanoparticles have a concentrated particle size distribution, smaller average particle size, better monodispersity, and stronger stability. Furthermore, compared with high-pressure homogenization and microjets in existing technologies, the ultrasonic microcavity reactor of this invention eliminates the need for a primary emulsion preparation step, shortening the emulsification cycle; ultrasonic emulsification prevents sample residue, enabling continuous long-term production of the product. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the ultrasonic microcavity reactor in an embodiment of the present invention; Figure 2 This is a photograph of the ultrasonic microcavity reactor in an embodiment of the present invention; Figure 3 This is a comparison diagram of the particle size distribution of emulsions prepared using the ultrasonic microcavity reactor of the present invention and the straight tubular reactor; Figure 4 This is a diagram illustrating the droplet emulsification process caused by "hurricane-shaped" cavitation bubbles inside the ultrasonic microcavity reactor of the present invention. Figure 5 This is a schematic diagram of the filamentary / vortex distribution of cavitation bubbles in a traditional straight-tube reactor.

[0018] The diagram is labeled as follows: 1. Reactor body; 11. Axial expansion section; 12. Axial contraction section; 2. Ultrasonic generating device. Detailed Implementation

[0019] To facilitate understanding of the present invention, specific embodiments are described in further detail below with reference to the accompanying drawings and examples. The following examples are illustrative of the invention but are not intended to limit its scope.

[0020] In the description of this invention, it should be understood that the terms "upper", "lower", "left", "right", "top", "bottom", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0021] Unless otherwise defined, all technical terms used herein have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the scope of the invention.

[0022] Example 1 An ultrasonic microcavity reactor, such as Figure 1 and Figure 2 As shown: The reactor includes a reactor body 1 and an ultrasonic generator 2. The reactor body 1 is installed in the ultrasonic radiation surface of the ultrasonic generator 2. The reactor body 1 contains at least one microcavity unit, which is a hollow pipe structure extending along a horizontal axis. The inner diameter of the microcavity unit, along the fluid flow direction, sequentially includes: an axially expanding section 11, whose cross-sectional area continuously increases from the inlet end to the outlet end of the axially expanding section 11; and an axially contracting section 12, located downstream of the axially expanding section 11, whose cross-sectional area continuously decreases from the inlet end to the outlet end of the axially contracting section 12.

[0023] In this embodiment, the axially expanding section 11 and the axially contracting section 12 are symmetrically distributed. Designing the axially expanding and contracting sections symmetrically facilitates the formation of "hurricane-shaped" cavitation bubbles by liquid cavitation within the microcavity unit. Of course, in some cases, the axially expanding and contracting sections can also be asymmetrical structures. Microcavity units with non-symmetrical structures can form other morphologies of cavitation bubbles, and the appropriate design can be selected based on the characteristics of the liquid to be processed.

[0024] In this embodiment, the inner diameter of the microcavity unit varies smoothly and continuously along the horizontal axis, forming a unique maximum cross-section at the midpoint between the axially expanding section 11 and the axially contracting section 12. By designing the inner diameter of the cavity to vary smoothly and continuously along the horizontal axis, it adapts to fluid flow and avoids fluid turbulence within the cavity. Of course, in some cases, there may also be a maximum cross-section section between the axially expanding and axially contracting sections. The maximum cross-section section is a tubular body with the same inner diameter along the horizontal axis. Using the maximum cross-section section can both increase the reaction chamber volume of the microcavity unit and allow for selection and adaptation according to the characteristics of the liquid to be processed.

[0025] In this embodiment, the microcavity unit has a microcavity diameter D = 4 mm; a microcavity length L = 12 mm; a diameter-to-lateral ratio L / D = 3; an axial tapering angle θ = 60°; and an axial tapering arc transition radius R = 8 mm.

[0026] In this embodiment, two microcavity units are connected in series within the reactor body, with a spacing S = 8 mm between adjacent microcavity units. By connecting multiple microcavity units in series, multi-stage enhanced treatment can be achieved.

[0027] In this embodiment, the two microcavity units connected in series are of the same size. By designing the microcavity units connected in series to be of the same size, the processing capacity can be estimated and enhanced. Therefore, a number of microcavity units can be selected and connected in series according to the characteristics of the liquid to be processed. Of course, in some cases, the microcavity units connected in series can be designed to be of different sizes as needed.

[0028] In this embodiment, the frequency range of the ultrasonic generator is 10kHz-100kHz, and the power density is 1-10W / mL.

[0029] In this embodiment, the material of the microcavity unit is quartz glass.

[0030] A method for using an ultrasonic microcavity reactor.

[0031] The aforementioned ultrasonic microcavity reactor was used to prepare propofol medium-chain fat emulsion as listed in the Chinese Pharmacopoeia. The preparation process is as follows: (1) Under nitrogen protection, add 9 mL soybean oil, 6 mL medium chain triglycerides, 0.5 g egg yolk lecithin and 0.05 mL oleic acid into a flask, stir evenly under preheating (70°C), add 1 g propofol and stir until a clear oil phase solution is formed, draw it out with a syringe and place it in a syringe pump for later use. (2) Under nitrogen protection, 0.6 mL of glycerol and 20 mL of water for injection are stirred thoroughly to form a solution. Then, sodium hydroxide is added to adjust the pH, and the solution is heated to 50°C. The solution is then drawn up with a syringe and placed in an injection pump for later use. (3) Ultrasonic emulsification: The oil phase and water phase were injected into an ultrasonic pipeline reactor at a flow ratio of 1:6.5, with a residence time of 20 s. Ultrasonic emulsification was performed in the ultrasonic microreactor with a power of 50 W and a frequency of 20 kHz to obtain an emulsion. During the preparation of the nanoemulsion, the ultrasonic power density P of the microcavity reactor... u The concentration is 4 W / mL, and the residence time is t. R The time is 20 seconds, and the total flow rate Q is 1.5 mL / min. The ultrasound parameter P is controlled. u t R D h 1 / 2 / (ρQ²) is 937, in the range of 200-20000, which enables the flowing droplets to be rapidly and homogeneously dispersed under the action of "hurricane-type" cavitation bubbles induced by ultrasound.

[0032] This invention also compared the effects of an ultrasonic microcavity reactor and a traditional 1-5mm straight tube reactor in the preparation of propofol long-chain fat emulsions as described in the Chinese Pharmacopoeia. The results are as follows: Figure 3 As shown. Figure 3 This image shows a comparison of the particle size distribution of emulsions prepared using the ultrasonic microcavity reactor of this invention and a straight-tube reactor. The comparative experiment shows that compared to conventional ultrasonic emulsification, the ultrasonic microcavity reactor of this invention has higher emulsification efficiency, smaller average particle size, better monodispersity, and stronger stability. The reason for this is that the ultrasonic microcavity reactor in this invention, through structural optimization, can form "hurricane-shaped" cavitation bubbles within the ultrasonic microcavity reactor; such as... Figure 4 As shown. In contrast, the cavitation bubbles in a traditional straight-tube reactor are distributed in a filamentary / vortex pattern; such as... Figure 5 As shown.

[0033] The above embodiments only illustrate one or more implementations of the present invention, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of protection of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the appended claims.

Claims

1. An ultrasonic microcavity reactor comprising a reactor body and an ultrasonic wave generating device, characterized in that: The reactor body is installed in the ultrasonic operation surface of the ultrasonic generator; at least one microcavity unit is arranged in the reactor body, the microcavity unit is a hollow pipe structure extending along the horizontal axis, and the inner diameter of the cavity of the microcavity unit includes, in sequence along the fluid flow direction, an axial gradually expanding section with a continuously increasing cross-sectional area from the inlet end to the outlet end of the axial gradually expanding section, and an axial gradually reducing section located downstream of the axial gradually expanding section with a continuously decreasing cross-sectional area from the inlet end to the outlet end of the axial gradually reducing section.

2. The ultrasonic microcavity reactor of claim 1, wherein, The axial gradually expanding section and the axial gradually reducing section are symmetrically distributed.

3. The ultrasonic microcavity reactor of claim 2, wherein, The inner diameter of the cavity of the microcavity unit changes smoothly along the horizontal axis, and a unique maximum cross section is formed at the intermediate position between the axial gradually expanding section and the axial gradually reducing section.

4. The ultrasonic microcavity reactor of claim 3, wherein, The microcavity diameter D of the microcavity unit is 2-9 mm, the microcavity length L is 2-20 mm, the diameter-lateral ratio L / D is 1.0-5.0, the axial gradually reducing section angle θ is 20-80°, and the axial gradually reducing section circular arc transition radius R is 2-20 mm.

5. The ultrasonic microcavity reactor of claim 4, wherein, A plurality of the microcavity units are connected in series in the reactor body, and the spacing S between adjacent microcavity units is 5-20 mm.

6. The ultrasonic microcavity reactor of claim 5, wherein, The size of each microcavity unit in the plurality of microcavity units connected in series is the same.

7. The ultrasonic microcavity reactor of claim 6, wherein, The frequency range of the ultrasonic generator is 10 kHz-100 kHz, and the power density is 1-10 W / mL.

8. The ultrasonic microcavity reactor of claim 7, wherein, The material of the microcavity unit is quartz glass, titanium alloy or stainless steel.

9. A method of using the ultrasonic microcavity reactor according to any one of claims 1-8, characterized by, P u t R D h 1 / 2 / (pQ²) is between 200 and 20000, where P u is the ultrasonic power density, t R is the residence time, p is the fluid density, Q is the total flow rate, D h is the hydraulic diameter.

10. The method of use of claim 9, wherein, When the nanoemulsion is prepared by using the ultrasonic microcavity reactor, the coarse emulsion, two-phase or multi-phase fluid is introduced into the microcavity unit in the ultrasonic microcavity reactor.

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