A microbubble generation method and apparatus

Abstract

The application discloses a micro-bubble generating method and device. The micro-bubble generating method and device utilize high-speed liquid jet impact on gas and the binding effect of a rotary body structure on bubbles, so that the bubbles are frequently sheared and broken by the liquid jet to generate a large amount of micro-bubbles. Meanwhile, the wall jet formed by the high-speed liquid jet impact on a flat plate promotes the uniform dispersion of the micro-bubbles. The micro-bubble generating method and device have the advantages of simple structure, good micro-bubble generating effect, large gas processing capacity, low energy consumption and good bubble dispersion and mixing effect.

Description

Technical Field

[0001] This invention belongs to the field of petrochemical technology, specifically relating to a microbubble generation method and apparatus. Background Technology

[0002] Compared to macrobubbles larger than 1000 μm, microbubbles have greater internal pressure and specific surface area, slower rising speed, higher interphase mass transfer rate, and stronger adsorption capacity, making them widely used in wastewater treatment, mineral flotation, and nanoparticle preparation. Commonly used microbubble preparation methods include dissolved gas evolution, electrolytic deposition, microfluidics, and gas-entrained dispersion.

[0003] Compared to other methods, the gas-induced dispersion method has advantages such as low equipment cost, easy scale-up, and simple operation, and is therefore widely used. Among them, the Venturi microbubble generator is the most widely used, which has the advantages of small bubble size and large bubble output, but it has disadvantages such as easy clogging, high energy consumption, and uneven bubble size. The supergravity microbubble generator is also used in the field of chemical synthesis. It produces small bubbles that are easy to scale up in parallel, but it has high energy consumption, poor bubble dispersion, and high equipment cost.

[0004] In summary, existing microbubble generation methods suffer from drawbacks such as low energy efficiency and high generator manufacturing costs. Therefore, there is an urgent need to develop microbubble generation methods that are energy efficient, structurally simple, have a high gas-liquid ratio, and produce small bubbles, and to apply them to industrial production. Summary of the Invention

[0005] To develop a microbubble generation technology with good microbubble generation effect, high energy utilization rate, and large processing capacity, this invention first provides a microbubble generation method, which includes the following steps: a liquid jet collides with a gas distributor to form an impact jet field containing an impact zone, a free jet zone, and a wall jet zone; a rotating shell structure is set in the impact jet field to control the bubble movement trajectory; gas is introduced from the impact zone, causing it to break up initially under high pulsating pressure, and some of the larger bubbles generated are confined in the free jet zone by the local negative pressure formed by the rotating shell structure, and are frequently sheared and broken by the liquid jet to generate a large number of microbubbles; another part of the smaller bubbles generated and the microbubbles escape from the rotating body structure and are fully dispersed under the transport of the wall jet in the wall jet zone, ultimately generating a large number of microbubbles with uniform size distribution.

[0006] In this invention, "microbubble" refers to a bubble with a diameter of less than 1 mm.

[0007] In this invention, "rotation surface" geometrically refers to a surface formed by rotating 360 degrees around an axis with an arbitrary curve as its generatrix, and "rotation shell" geometrically refers to a shell composed solely of rotation surfaces or a shell composed of rotation surfaces and a plane.

[0008] In this invention, the arrangement of the liquid nozzle, gas distributor, and rotating shell structure satisfies the following: the central axes of the gas distributor, liquid nozzle, and rotating shell structure are on a straight line; the outlets of the gas distributor and liquid nozzle are opposite each other; and the liquid nozzle and rotating shell structure are arranged above the gas distributor. When there is a gas distributor, there must also be a liquid nozzle and a rotating shell structure. That is to say, in the microbubble generator, the number of gas distributors, liquid nozzles, and rotating shell structures is the same.

[0009] According to a preferred embodiment of the present invention, the generatrix of the rotating shell structure is an arc, the curvature and the rate of change of curvature of the arc are not always 0, and the cross-sectional diameter of the end connected to the liquid inlet pipe is the smallest, while the cross-sectional diameter of the open end is the largest.

[0010] To achieve the aforementioned method, the present invention provides a microbubble generating device, comprising: a liquid injection device consisting of a liquid nozzle and an inlet pipe connected thereto; a gas injection component consisting of a gas distributor and an inlet pipe connected thereto; and a rotating housing structure with an opening at one end and an open end at the other. The liquid injection device passes through the opening at the end of the rotating housing structure so that the liquid nozzle is located inside the rotating housing structure. The centers of the liquid injection device, the gas injection component, and the rotating housing structure are on the same axis, and the liquid nozzle and the rotating housing structure are located above the gas distributor. The liquid injection device and the gas injection component are arranged opposite to each other. There is a distance between the gas distributor and the open end section of the rotating housing.

[0011] According to a preferred embodiment of the present invention, the gas distributor may be a disc-shaped structure. The material of the rotating shell structure has a contact angle with the liquid phase greater than 90° and cannot completely adsorb the gas.

[0012] According to a preferred embodiment of the present invention, the gas distributor has at least one air hole, wherein the diameter of the air hole is 50 μm-6 mm, preferably 200 μm-2 mm. According to some embodiments of the present invention, the air holes on the gas distributor are arranged within a circle extending from the center to 0.5 times the diameter of the gas distributor, and at least one air hole has a diameter of 50 μm-6 mm. According to some embodiments of the present invention, the gas delivered by the inlet pipe is ejected from the air hole, and the outlet diameter of the inlet pipe should be such that the outlet of the inlet pipe completely covers the air hole on the gas distributor; the outlet diameter of the inlet pipe is less than or equal to the diameter of the gas distributor.

[0013] According to a preferred embodiment of the present invention, the liquid nozzle may be selected from a straight pipe of equal diameter or a straight pipe of reduced diameter, wherein the selected straight pipe is centrally symmetrical and easy to assemble with the rotating body structure.

[0014] According to a preferred embodiment of the present invention, the distance between the gas distributor and the liquid nozzle is 0.5-50 mm, preferably 1-30 mm; the distance between the open end of the rotating housing structure and the gas distributor is 0.5-20 mm, preferably 0.5-15 mm.

[0015] According to a preferred embodiment of the present invention, the ratio of the diameter of the open end section of the rotating shell structure to the diameter of the gas distributor is 0.5-4, preferably 0.5-2, and is selected according to the physical properties of the continuous phase liquid.

[0016] According to a preferred embodiment of the present invention, the diameter of the open end section of the rotating housing is 2-15 times, preferably 6-10 times, the diameter of the liquid nozzle outlet section.

[0017] According to a preferred embodiment of the present invention, the cross-sectional diameter of the gas distributor is 3-15 times, preferably 6-10 times, the cross-sectional diameter of the liquid nozzle outlet.

[0018] According to a preferred embodiment of the present invention, the flow velocity of the liquid flowing out of the liquid nozzle (calculated based on the cross-sectional area of ​​the liquid nozzle outlet) is greater than 1.2 m / s, preferably greater than 2.2 m / s, and the ratio of the liquid phase volumetric flow rate input to the liquid nozzle to the gas phase volumetric flow rate flowing out of the gas distributor (calculated based on the cross-sectional area of ​​the gas outlet) is 0.5-5, preferably 1-3.

[0019] This invention also provides a microbubble generation method based on the above-mentioned device, which effectively improves the utilization rate of energy input per unit liquid and controls the bubble movement trajectory to cause multiple breakages. The method includes: liquid being transported by an inlet pipe and ejected as a liquid jet through a liquid nozzle; gas being transported by an inlet pipe and distributed by a gas distributor; the gas and liquid interacting within the microbubble generation device to generate microbubbles with uniform size distribution; controlling the outlet flow velocity of the liquid nozzle to be greater than 1.2 m / s; and adjusting the outlet flow velocity u (m / s), the distance H (m) between the liquid nozzle and the gas distributor, the distance l (m) between the open end of the rotating body and the gas distributor, the diameter D0 (m) of the open end cross-section of the rotating body, and the diameter d of the liquid nozzle. j (m), gas outlet velocity u g (m / s), gas outlet diameter d g (m) can control the average Souter size of the bubble d 32 (m) and maximum bubble size d m (m):

[0020]

[0021] Where, ρ g ρ l (kg / m 3 ) represent the gas density and liquid density, respectively, μ g μ l (Pa·s) represents the gas viscosity and liquid viscosity, respectively, in g (m / s). 2 ) represents gravitational acceleration, and the values ​​of k1 and k2 are only related to the physical properties. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the microbubble generator provided by the present invention.

[0023] Figure 2 This is a schematic diagram of the cylindrical gas distributor provided by the present invention.

[0024] Figure 3 This is a verification diagram of the maximum bubble size relationship provided by the present invention.

[0025] Figure 4 This is a verification diagram of the Sotter average size relationship provided by the present invention. Detailed Implementation

[0026] The present invention will be described in detail below with reference to the embodiments, but the present invention is not limited to the following embodiments.

[0027] The following combination Figure 1-2 The microbubble generator provided by this invention will be described in detail.

[0028] In some embodiments of the present invention, the structure of the microbubble generator is as follows: Figure 1As shown, the system includes a liquid inlet pipe 1, a rotating shell structure 2, a liquid nozzle 3, a gas distributor 4, and an air inlet pipe 5. The air inlet pipe and liquid inlet pipe are cylindrical. The outlet end of the air inlet pipe is connected to the gas distributor, and the center of the gas distributor is on the same axis as the center of the rotating shell structure. One end of the liquid inlet pipe is connected to the liquid nozzle, and the outlet of the liquid nozzle is located inside the rotating shell structure. The liquid nozzle and the rotating shell structure are located above the gas distributor. The liquid nozzle is a circular tube with an outlet diameter of 3-18 mm. The gas distributor structure is disc-shaped (diameter 15-40 mm, height-to-diameter ratio 0.02-0.1, disc diameter greater than or equal to the outlet diameter of the air inlet pipe). The disc has symmetrically arranged holes within a range of 0.5 times the disc diameter centered on the center, with hole diameters of 0.5-4 mm. The rotating shell structure is made of a sparse continuous phase material to ensure that the liquid phase does not adhere to the material. The diameter of the cross-section of the rotating structure and its open end is 15-50 mm. The distance l between the liquid outlet and the outlet end of the gas distributor is 0.5-30 mm. The distance from the open end of the rotating structure to the gas distributor is 0.5-20 mm. The liquid flow rate in the inlet pipe ensures that the liquid velocity flowing out of the liquid nozzle is above 1.2 m / s, and the ratio of the liquid phase volumetric flow rate flowing out of the liquid nozzle to the gas phase volumetric flow rate input to the gas distributor is 1-3.

[0029] Example 1

[0030] The structure of the microbubble generator is as follows Figure 1 As shown, the structure includes a liquid inlet pipe 1, a rotating housing structure 2, a liquid nozzle 3, a gas distributor 4, and an air inlet pipe 5. Both the liquid inlet pipe and the air inlet pipe are cylindrical. The outlet end of the air inlet pipe is connected to the gas distributor, which completely covers the outlet end of the air inlet pipe. The center of the gas distributor is on the same axis as the center of the rotating housing structure. One end of the liquid inlet pipe is connected to the liquid nozzle, and the outlet of the liquid nozzle is located inside the rotating housing structure. The liquid nozzle and the rotating structure are located above the gas distributor. The liquid nozzle is a circular pipe with an outlet diameter of 4 mm. The gas distributor is disc-shaped (25 mm in diameter) with a 2 mm hole at its center. The rotating structure is made of hydrophobic material (PMMA), and the diameter of its open end section is 30 mm. The distance H between the liquid nozzle outlet and the gas distributor is 20 mm, and the distance l between the open end of the rotating structure and the gas distributor is 5 mm. The liquid velocity exiting the nozzle was 1.66 m / s, and the ratio of gas volumetric flow rate to liquid volumetric flow rate was 0.23. Using air as the gaseous experimental medium and water as the liquid experimental medium, a high-speed camera was used to measure the size and distribution of bubbles generated by the microbubble generator. Figure 3 , Figure 4 As shown, the generated bubble size is 500-1300μm, the microbubble number fraction is 65%, and the radial dispersion width of the bubbles is 30mm (1.2 times the diameter of the gas distribution disk).

[0031] Example 2

[0032] The only difference from Example 1 is that the liquid velocity flowing from the liquid nozzle is 2.66 m / s, and a high-speed camera is used to photograph the bubbles generated by the microbubble generator. Figure 3 , Figure 4 As shown, the generated bubble size is 300-1000μm, the microbubble number fraction is 76%, the ratio of gas volume flow rate to liquid volume flow rate is 0.14, and the radial dispersion width of the bubbles is 33mm (1.32 times the diameter of the gas distribution disk).

[0033] Example 3

[0034] The only difference from Example 1 is that the liquid velocity flowing from the liquid nozzle is 3.55 m / s, and a high-speed camera is used to photograph the bubbles generated by the microbubble generator. Figure 3 , Figure 4 As shown, the generated bubble size is 200-900μm, the microbubble number fraction is 100%, the ratio of gas volume flow rate to liquid volume flow rate is 0.11, and the radial dispersion width of the bubbles is 38mm (1.52 times the diameter of the gas distribution disk).

[0035] Example 4

[0036] The only difference from Example 3 is that four 1mm diameter pores are evenly distributed on the disc-shaped gas distributor, with the center of the pores 3mm away from the center of the gas distributor. A high-speed camera is used to photograph the bubbles generated by the microbubble generator. The generated bubble size is 200-1000μm, the microbubble number fraction is 100%, the ratio of gas volume flow rate to liquid volume flow rate is 0.11, and the radial dispersion width of the bubbles is 39mm (1.56 times the diameter of the gas distribution disc).

[0037] Example 5

[0038] The only difference from Example 3 is that the distance H between the liquid nozzle outlet and the gas distributor is 15mm. A high-speed camera is used to photograph the bubbles generated by the microbubble generator. The generated bubble size is 200-1100μm, the microbubble number fraction is 96%, the ratio of gas volume flow rate to liquid volume flow rate is 0.11, and the radial dispersion width of the bubbles is 43mm (1.72 times the diameter of the gas distribution disk).

[0039] Example 6

[0040] The only difference from Example 3 is that the cross-sectional diameter of the flow field connecting end of the rotating body component is 45mm. A high-speed camera is used to photograph the bubbles generated by the microbubble generator. The generated bubble size is 200-1000μm, the microbubble number fraction is 100%, the ratio of gas volume flow rate to liquid volume flow rate is 0.11, and the radial dispersion width of the bubbles is 45mm (1.8 times the diameter of the gas distribution disk).

[0041] Comparative Example 1:

[0042] The only difference from Example 1 is that the distance H between the liquid nozzle outlet and the gas distributor is 60 mm (more than 50 mm), the distance l between the open end of the rotating body and the gas distributor is 40 mm, a high-speed camera is used to photograph the bubbles generated by the microbubble generator, the bubble size is 1300-2900 μm, the microbubble number fraction is 0%, the ratio of gas volume flow rate to liquid volume flow rate is 0.23, and the radial dispersion width of the bubbles is 51 mm (2.04 times the diameter of the gas distribution disk).

[0043] Comparative Example 2:

[0044] The only difference from Example 3 is that the distance H between the liquid nozzle outlet and the gas distributor is 60 mm (more than 50 mm), the distance l between the open end of the rotating body and the gas distributor is 40 mm, a high-speed camera is used to photograph the bubbles generated by the microbubble generator, the bubble size is 1100-2300 μm, the microbubble number fraction is 0%, the ratio of gas volume flow rate to liquid volume flow rate is 0.11, and the radial dispersion width of the bubbles is 57.5 mm (2.3 times the diameter of the gas distribution disk).

[0045] Comparative Example 3:

[0046] The only difference from Example 3 is that the vents on the gas distributor are set on a circle from the center to 0.8 times the diameter of the gas distributor (above the range of 0.5 times the diameter of the gas distributor). A high-speed camera is used to photograph the bubbles generated by the microbubble generator. The generated bubble size is 900-1900μm, the microbubble number fraction is 15%, the ratio of gas volume flow rate to liquid volume flow rate is 0.11, and the radial dispersion width of the bubbles is 38mm (1.52 times the diameter of the gas distribution disk).

[0047] Comparative Example 4:

[0048] The only difference from Example 3 is that the cross-sectional diameter of the flow field connecting end of the rotating body component is 75mm (more than 15 times the cross-sectional diameter of the liquid nozzle outlet). A high-speed camera is used to photograph the bubbles generated by the microbubble generator. The generated bubble size is 1600-4500μm, the microbubble number fraction is 0%, the bubble aggregation is severe, and the ratio of gas volume flow rate to liquid volume flow rate is 0.11.

[0049] It should be noted that the embodiments and comparative examples described above are only for explaining the present invention and do not constitute any limitation on the present invention. The present invention has been described with reference to typical embodiments, but it should be understood that the terms used therein are descriptive and explanatory terms, not limiting terms. Modifications can be made to the present invention within the scope of the claims, and revisions can be made to the present invention without departing from the scope and spirit of the present invention. Although the present invention described herein relates to specific methods, materials, and embodiments, it does not mean that the present invention is limited to the specific examples disclosed herein; on the contrary, the present invention can be extended to all other methods and applications having the same function.

Claims

1. A microbubble generation method based on a microbubble generator, characterized in that, The microbubble generator comprises a liquid injection device consisting of a liquid nozzle and a liquid inlet pipe connected thereto, a gas injection component consisting of a gas distributor and an air inlet pipe connected thereto, and a rotating housing structure with an opening at one end and an open end at the other. The liquid injection device passes through the opening at the end of the rotating housing structure so that the liquid nozzle is located inside the rotating housing structure. The centers of the liquid injection device, the gas injection component, and the rotating housing structure are on the same axis, and the liquid nozzle and the rotating housing structure are located above the gas distributor. The liquid injection device and the gas injection component are configured opposite to each other; There is a distance between the gas distributor and the open end section of the rotating shell; The microbubble generation method includes: Liquid is transported through an inlet pipe and ejected as a liquid jet through a liquid nozzle; gas is transported through an inlet pipe and distributed by a gas distributor; the gas and liquid interact within the microbubble generator to produce microbubbles with uniform size distribution; specifically, the liquid jet collides with the gas distributor to form an impact jet field containing an impact zone, a free jet zone, and a wall jet zone; a rotating shell structure is set in the impact jet field to control the bubble trajectory; gas is introduced from the impact zone, causing it to break up initially under high pulsating pressure; some of the larger bubbles are confined in the free jet zone by the local negative pressure formed by the rotating shell structure, and are frequently sheared and broken by the liquid jet to generate a large number of microbubbles; another portion of the smaller bubbles and the microbubbles escape from the rotating structure and are fully dispersed under the transport of the wall jet in the wall jet zone, ultimately producing a large number of microbubbles with uniform size distribution. The outlet flow velocity of the liquid nozzle is controlled to be greater than 1.2 m / s; the ratio of the liquid phase volumetric flow rate input to the liquid injection device to the gas phase volumetric flow rate input to the gas injection component is 0.5-10; the outlet flow velocity of the liquid nozzle is adjusted... Distance between liquid nozzle and gas distributor Distance from the open end of the rotating body to the gas distributor Diameter of the open end section of the rotating body Liquid nozzle diameter Gas outlet velocity Gas outlet diameter Capable of controlling the average size of bubbles (Souter). With the maximum bubble size : ； ； ； ； in, , These are the gas density and liquid density, respectively, in kg / m³. 3 , , Here, g represents the viscosity of gases and liquids, in Pa·s, and g is the acceleration due to gravity, in m / s². 2 , , The constant is a property that depends only on the physical properties. , The unit is m / s. , , , , , , All units are in meters (m).

2. The microbubble generation method according to claim 1, characterized in that, The generatrix of the rotating shell structure is an arc. The curvature and rate of change of curvature of the arc are not always 0. The cross-sectional diameter of the end connected to the liquid inlet pipe is the smallest, and the cross-sectional diameter of the open end is the largest.

3. The microbubble generation method according to claim 1, characterized in that, The gas distributor has a disc-shaped structure.

4. The microbubble generation method according to claim 1, characterized in that, The material of the rotating shell structure has a contact angle greater than 90° with the liquid phase and cannot completely adsorb gas.

5. The microbubble generation method according to claim 1, characterized in that, The gas distributor has vents located within a circle extending from the center to 0.5 times the diameter of the gas distributor, and at least one vent has a diameter of 50 μm to 6 mm.

6. The microbubble generation method according to any one of claims 1-5, characterized in that, The distance between the liquid nozzle outlet and the gas distributor is 0.5-50 mm; the distance between the open end of the rotating housing structure and the gas distributor is 0.5-30 mm.

7. The microbubble generation method according to any one of claims 1-5, characterized in that, The diameter of the open end section of the rotary housing structure is 2-15 times the diameter of the liquid nozzle outlet section, the diameter of the gas distributor section is 3-15 times the diameter of the liquid nozzle outlet section, and the diameter of the open end section of the rotary housing is 0.5-4 times the diameter of the gas distributor section.

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