Liquid-phase mixing bubble generator, gas-liquid bubbling bed reactor and its reaction method

Abstract

This invention relates to the field of gas-liquid mixing reactions, and discloses a liquid-phase mixing bubble generator, a gas-liquid bubbling bed reaction device, and a reaction method thereof. The liquid-phase mixing bubble generator includes a Venturi tube (1) and an outlet straight pipe (15). The Venturi tube (1) includes a converging section (3), a throat straight section (4), and a diverging section (7). The outlet straight pipe (15) is connected to the diverging section (7). A liquid inlet (17) penetrating the pipe wall is provided on the throat straight section (4), and a swirling gas hole (9) penetrating the pipe wall at an angle to the radial direction is provided on the outlet straight pipe (15). Through the above technical solution, another liquid and a gas can be added sequentially to a liquid to achieve mixing of the two liquids and gases, resulting in more uniform mixing between the liquid phases. Furthermore, the bubbles are mixed in the liquid at a smaller size, improving the mixing uniformity.

Description

Technical Field

[0001] This invention relates to the field of gas-liquid mixing reaction, specifically to a liquid-phase mixing bubble generator, and also to a gas-liquid bubbling bed reaction device and its reaction method. Background Technology

[0002] The gas-liquid bubbling bed reactor is an important type of multiphase reactor. The gas and liquid phases flow upwards in parallel. The liquid phase is the continuous phase, and the gas phase is the dispersed phase. The gas phase is dispersed in the liquid phase in the form of bubbles. The smaller the bubbles, the larger the gas-liquid interface area, which is more conducive to the mass transfer between the gas and liquid phases and can improve the performance of the reactor.

[0003] CN109200839A discloses a Venturi-type microbubble generator, including a circulating pump, a bubble generator, and pipelines. A water storage system is sequentially connected to the circulating pump and the bubble generator via the pipelines, forming a loop. The bubble generator includes a pre-diffuser section, a rectifying section, a Venturi tube, a transition section, and a post-contraction section connected sequentially. The throat of the Venturi tube is connected to a ventilation system via a vent pipe, and the ventilation system introduces a gas-liquid mixture into the Venturi tube. A rectifier is installed in the rectifying section. This design fully utilizes the high-velocity water flow shear formed when the liquid passes through the throat region of the Venturi tube and the high-intensity eddy current disturbance generated during the diffuser section. It achieves high bubble generation efficiency, large quantity, no pollution, energy saving, and safe system operation. Furthermore, the flow meter, valves, and circulating pump are all mature products. The entire device is simple in design, easy to install, and has low operating and maintenance costs.

[0004] CN109731491A discloses a method and apparatus for generating micro / nano bubbles using a dual-flow collision jet, comprising two Venturi tubes mounted on a fixed disk. Each Venturi tube has an inlet at its upper end, located at the center of the fixed disk. Several fixing rods are inserted into the fixed disk, each with a screw. Each fixing rod is perpendicularly connected to two fixed disks, and the two fixed disks are parallel to each other. A contraction tube is connected below the inlet, forming a single unit. A throat is located at one end of the contraction tube. An air inlet is located on the Venturi tube, and an outlet is located at the end of the Venturi tube opposite the inlet. A small gap exists between the end of the contraction tube and the throat, and a gap exists between the outer wall of the contraction tube and the air inlet. A collision gap exists between the two Venturi tubes. This scheme employs a dual-flow collision structure design, where two streams of fluid containing micro-nano bubbles collide head-on, generating turbulence intensity 1.5-3 times higher than that of traditional single-tube jets. This promotes secondary breakup of micro-nano bubbles, resulting in a greater number of bubbles with more uniform particle size. The collision of these two foam streams transforms the diffusion of micro-nano bubbles into a 360° annular disk shape, which is beneficial for their diffusion. Due to the special collision structure design, the reaction force from the water is minimal, thus eliminating the need for additional fixing devices when operating underwater, greatly improving convenience. Compared to traditional single-tube Venturi tube devices, this invention requires lower energy consumption to produce the same number of micro-nano bubbles with the same particle size.

[0005] However, in actual production, the liquid phases involved in the reaction are often not singular; rather, two liquid phases need to be mixed with a gas phase, allowing the gas phase to generate microbubbles within the liquid mixture. Neither of the above two methods, nor other existing technologies, disclose a device suitable for mixing a gas phase with two liquid phases to generate microbubbles. Summary of the Invention

[0006] The purpose of this invention is to provide a liquid-phase mixing bubble generator that solves the problems of uneven mixing between liquid phases, large bubble size, non-uniform bubble size in existing bubble generators, uneven liquid mixing, low heat and mass transfer efficiency, and high energy consumption in gas-liquid bubbling bed reactors.

[0007] To achieve the above objectives, the present invention provides a liquid-phase mixing bubble generator, wherein the liquid-phase mixing bubble generator includes a Venturi tube and an outlet straight pipe, the Venturi tube includes a converging section, a throat straight section and a diverging section, the outlet straight pipe is connected to the diverging section, the throat straight section is provided with a liquid inlet penetrating the pipe wall, and the outlet straight pipe is provided with a swirling air hole penetrating the pipe wall at an angle to the radial direction.

[0008] Optionally, the liquid inlet is an annular gap.

[0009] Optionally, the cross-section of the liquid inlet tapers along the flow direction.

[0010] Optionally, the swirling air hole penetrates the pipe wall along the tangential direction of a concentric circle smaller than the inner circumference of the outlet straight pipe.

[0011] Alternatively, the liquid-phase mixing bubble generator includes a liquid phase chamber surrounding the throat straight section at the liquid inlet, and / or the liquid-phase mixing bubble generator includes a gas phase chamber including the outlet straight pipe at the swirling gas orifice.

[0012] Optionally, the liquid-phase mixing bubble generator includes a sheet-like liquid-phase vortex element disposed in the straight section of the throat and the gradually expanding section.

[0013] Optionally, the liquid-phase mixing bubble generator includes a sheet-like mixing element disposed in the straight section of the throat and located upstream of the swirling air hole.

[0014] Optionally, the liquid-phase mixing bubble generator includes an accelerator disposed in the outlet straight pipe and located at the swirling gas hole, wherein an annular gap is formed between the accelerator and the inner circumferential surface of the outlet straight pipe.

[0015] Optionally, the accelerating component includes a tapered section, on which a sheet-like gas-liquid vortex element is provided.

[0016] Optionally, the liquid-phase mixing bubble generator includes a mesh or grid-like bubble-breaking plate disposed at one end of the outlet straight pipe away from the diffuser section.

[0017] Optionally, the liquid-phase mixing bubble generator includes an inlet straight pipe connected to the tapering section.

[0018] In addition, the present invention also provides a gas-liquid bubbling bed reactor, wherein the gas-liquid bubbling bed reactor includes a bubbling bed, a circulation pipeline, and a liquid-phase mixing bubble generator according to the above scheme disposed at the lower part of the bubbling bed. The bubbling bed is provided with a gas phase outlet at the top, a liquid phase outlet at the side, a separation liquid inlet connected to the liquid inlet, a gas phase inlet connected to the swirling gas hole, a circulation outlet at the top, and a circulation inlet at the bottom. The circulation pipeline is connected to the circulation inlet and the circulation outlet, and a raw material inlet is connected to the circulation pipeline.

[0019] Optionally, the circulation pipeline is equipped with a heat exchange unit and a power component.

[0020] Optionally, the gas-liquid bubbling bed is provided with a near-wall ring pipe located above the liquid phase mixing bubble generator.

[0021] In addition, the present invention also provides a reaction method for a gas-liquid bubbling bed reactor, wherein the reaction method adopts the gas-liquid bubbling bed reactor described above.

[0022] The above technical solution allows for the sequential addition of one liquid and one gas to a liquid, achieving mixing of the two liquids and gases. This results in more uniform mixing between the liquid phases, and the bubbles are mixed in the liquid at a smaller size, improving the uniformity of mixing. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the liquid-phase mixing bubble generator according to an embodiment of the present invention;

[0024] Figure 2 This is a schematic diagram of the gas-liquid bubbling bed reactor according to an embodiment of the present invention;

[0025] Figure 3 This is a schematic diagram of the near-wall annular tube according to an embodiment of the present invention;

[0026] Figure 4 This is a schematic diagram of the hybrid component according to an embodiment of the present invention;

[0027] Figure 5 This is a schematic diagram of the accelerating component and the gas-liquid vortex component described in the embodiments of the present invention.

[0028] Explanation of reference numerals in the attached figures

[0029] 1-Venturi tube, 2-Inlet straight pipe, 3-Converging section, 4-Throat straight section, 5-Liquid inlet pipe, 6-Liquid phase chamber, 7-Diverging section, 8-Liquid phase vortex component, 9-Swirl gas hole, 10-Mixing component, 11-Inlet pipe, 12-Gas phase chamber, 13-Accelerator component, 14-Gas-liquid vortex component, 15-Outlet straight pipe, 16-Bubble breaking plate, 17-Liquid inlet, 20-Bubble bed, 21-Liquid phase mixing bubble generator, 22-Gas phase inlet, 23-Separated liquid inlet, 24-Raw material inlet, 25-Circulation outlet, 27-Power component, 28-Circulation inlet, 29-Liquid phase outlet, 30-Gas phase outlet, 31-Near-wall ring pipe. Detailed Implementation

[0030] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0031] The present invention provides a liquid phase mixing bubble generator, wherein the liquid phase mixing bubble generator includes a Venturi tube 1 and an outlet straight pipe 15. The Venturi tube 1 includes a converging section 3, a throat straight section 4 and a diverging section 7. The outlet straight pipe 15 is connected to the diverging section 7. A liquid inlet 17 penetrating the pipe wall is provided on the throat straight section 4. A swirling air hole 9 penetrating the pipe wall at an angle to the radial direction is provided on the outlet straight pipe 15.

[0032] The Venturi tube 1 comprises a converging section 3 with a gradually decreasing inner diameter, a straight throat section 4 with a basically constant inner diameter, and a diverging section 7 with a gradually increasing inner diameter. These three sections are connected sequentially along the flow direction. Fluid, such as a liquid, is introduced into the Venturi tube 1 through the converging section 3. The cone angle of the converging section 3 is 10–60°, and the cone angle of the diverging section 7 is 5–50°.

[0033] Among them, a liquid inlet 17 is formed on the straight section 4 of the throat. Another liquid (usually a different liquid, but it can also be the same liquid) can be injected into the Venturi tube 1 through the liquid inlet 17, so that the liquid entering from the converging section 3 and the liquid entering from the liquid inlet 17 are uniformly mixed.

[0034] The converging section 3 can be used to introduce the raw material liquid, and the liquid inlet 17 can be used to introduce the separated liquid obtained from the downstream distillation unit, so that the raw material liquid and the separated liquid are fully mixed, avoiding the separation of the high-speed liquid flow from the wall, enhancing the turbulence intensity, generating a large number of small eddies, and promoting the homogeneous mixing of the raw material liquid and the separated liquid.

[0035] In addition, a swirling air hole 17 is provided on the outlet straight pipe 15 connected to the gradually expanding section 7. The swirling air hole 17 extends in a direction that forms an angle with the radial direction, that is, there is an angle between its extension direction and the radial direction. The airflow entering the outlet straight pipe 15 from the swirling air hole 17 forms an angle with the radial direction, thereby forming a swirling flow in the outlet straight pipe 15. This can reduce the size of the bubbles formed in the liquid, prolong the residence time of the bubbles in the outlet straight pipe 15, and make the gas and liquid mix evenly.

[0036] In this scheme, another liquid and a gas can be added to a liquid one after another to achieve mixing of the two liquids and gases, so that the bubbles are mixed in the liquid with smaller sizes, thereby improving the mixing uniformity.

[0037] The liquid inlet 17 is an annular gap. The liquid inlet 17 is formed as an annular gap extending in the circumferential direction, which is equivalent to dividing the throat straight section 4 into two segments that maintain an axial gap, thereby injecting liquid into the throat straight section 4 in a more comprehensive manner in the circumferential direction.

[0038] The cross-section of the liquid inlet 17 gradually decreases along the flow direction. This gradual reduction in the cross-section of the liquid inlet 17 causes a gradual increase in the liquid flow velocity, improving the mixing effect of the two liquids. Figure 1 As shown, in the cross-section passing through the central axis, the dimension of the liquid inlet 17 decreases along the axial direction. Specifically, the taper angle of the liquid inlet 17 is 0~45°, and the minimum annular gap is 0.05~0.2 times the inner diameter of the throat straight section 4.

[0039] Furthermore, the swirling air hole 9 extends through the pipe wall along the tangential direction of a concentric circle smaller than the inner circumferential radius of the outlet straight pipe 15. In other words, the angle between the swirling air hole 9 and the radial direction is acute, causing the airflow to form a swirling flow near the inner circumferential surface of the outlet straight pipe 15, resulting in more thorough mixing of the gas and liquid and improved mixing uniformity. The radius of the concentric circle of the outlet straight pipe 15 tangent to the extending direction of the swirling air hole 9 is the tangent radius.

[0040] Furthermore, the liquid-phase mixing bubble generator includes a liquid phase chamber 6 surrounding the throat straight section 4 at the liquid inlet 17, and / or, the liquid-phase mixing bubble generator includes a gas phase chamber 12 including the outlet straight pipe 15 at the swirling gas hole 9. The liquid phase chamber 6 surrounds the portion of the throat straight section 4 where the liquid inlet 17 is located. The liquid phase chamber 6 can contain liquid, forming a stable hydraulic environment for injecting liquid into the throat straight section 4. Additionally, the liquid phase chamber 6 is connected to an inlet pipe 5, which can be connected to a liquid supply device, such as a separated liquid supplied by a downstream distillation unit, to supply the corresponding liquid to the hydraulic chamber. The liquid phase chamber 6 provides a communication medium between the inlet pipe 5 and the liquid inlet 17, acting as a buffer chamber for the liquid, and can form a sealed environment around the liquid inlet 17 to prevent leakage.

[0041] Furthermore, the liquid-phase mixing bubble generator includes sheet-like liquid-phase vortex elements 8 disposed in the throat section 4 and the expanding section 7. The liquid-phase vortex element 8 has a thin sheet structure, with a maximum height at the front end of 0.05~0.01 times the inner diameter of the throat section 4 and a maximum height at the rear end of 0.5~1.0 times the inner diameter of the throat section 4, falling within the range of 0.5~1 times the length of the throat section 4 and 0~0.5 times the length of the expanding section 7. The liquid-phase vortex element 8 can be triangular, quadrilateral, arc-shaped, etc., or can be combined with each other. The throat section 4 and the expanding section 7 can be provided with 2~20 liquid-phase vortex elements 8 in the circumferential direction.

[0042] Additionally, the liquid-phase mixing bubble generator includes a sheet-like mixing element 10 disposed in the throat straight section 4 and located upstream of the swirling air hole 9. For example... Figure 1 As shown, a swirling air hole 9 is provided at the rear of the outlet straight pipe 15, and a mixing element 10 is provided at the front of it. The axial dimension of the mixing element 10 is 0.2~0.8 of the portion of the outlet straight pipe 15 upstream of the swirling air hole 9. It can be a fin, a twisted fin, an arched fin, etc., or a combination thereof. (Refer to...) Figure 4As shown. The mixing element 10, located before the swirl orifice 9, improves the mixing uniformity of the two liquids.

[0043] Furthermore, the liquid-phase mixing bubble generator includes an accelerator 13 disposed within the outlet straight pipe 15 and located at the swirling gas hole 9, forming an annular gap between the accelerator 13 and the inner circumferential surface of the outlet straight pipe 15. The fluid velocity increases at the annular gap between the accelerator 13 and the outlet straight pipe 15, allowing for sufficient contact with the gas entering through the swirling gas hole 9, reducing bubble size, and thus improving the uniformity of gas-liquid mixing. The accelerator 13 can be spherical, elliptical, conical, etc., or a combination thereof. Figure 1 As shown, the accelerator 13 includes a hemispherical front part and a conical rear part. The minimum annular gap between the accelerator 13 and the outlet straight pipe 15 corresponds to the position of the swirling air hole 9, and the cross-section of the minimum annular gap is 0.03 to 0.1 of the cross-sectional area of ​​the outlet straight pipe 15.

[0044] Among them, such as Figure 5 As shown, the accelerating component 13 includes a tapered section, on which a sheet-like gas-liquid vortex component 14 is disposed. This tapered section can be... Figure 1 The conical shape shown is provided on the outer circumferential surface of the gas-liquid vortex component 14. The gas-liquid vortex component 14 is a thin sheet structure, with a maximum height of 0.01 to 0.05 times the inner diameter of the outlet straight pipe 15. The gas-liquid vortex component 14 can also be a combination of other geometric shapes such as triangle, quadrilateral, and arc.

[0045] Furthermore, the liquid-phase mixing bubble generator includes a mesh or grid-like bubble-breaking plate 16 disposed at one end of the outlet straight pipe 15 away from the diffuser section 7. The bubble-breaking plate 16 forms through holes to allow fluid to pass through and can break bubbles therein to form smaller bubbles, thereby improving the uniformity of gas-liquid mixing.

[0046] Additionally, the liquid-phase mixing bubble generator includes an inlet straight pipe 2 connected to the tapered section 3. For example... Figure 1 As shown, the inlet straight pipe 2 is also connected to two or more bends for connection with other liquid supply equipment. The ratio of the cross-sectional area of ​​the throat straight section 4 to that of the inlet straight pipe 2 is 0.01 to 0.2, and the ratio of the cross-sectional area of ​​the inlet straight pipe 2 to that of the outlet straight pipe 15 is 0.8 to 1.2.

[0047] In addition, the present invention also provides a gas-liquid bubbling bed reaction device, wherein, as Figure 2As shown, the gas-liquid bubbling bed reactor includes a bubbling bed 20, a circulation pipeline, and a liquid-phase mixing bubble generator 21 as described in the above embodiment, located at the lower part of the bubbling bed 20. The bubbling bed 20 is provided with a gas phase outlet 30 at the top, a liquid phase outlet 29 at the side, a separation liquid inlet 23 connected to the liquid inlet 17, a gas phase inlet 22 connected to the swirling gas hole 9, a circulation outlet 25 at the top, and a circulation inlet 28 at the bottom. The circulation pipeline connects the circulation inlet 28 and the circulation outlet 25, and a raw material inlet 24 is connected to the circulation pipeline. The liquid-phase mixing bubble generator 21 extends vertically. The swirling gas hole 9 is connected to an external gas supply device through the gas phase inlet 22, and the liquid inlet 17 is connected to a liquid supply device through the separation liquid inlet 23. The inlet end of the venturi tube 1 is located at the lower part of the bubbling bed 20 to allow liquid from the circulation pipeline to enter.

[0048] The circulation outlet 25 is located at the top of the bubbling bed 20, at a height of 0.5 to 0.8 times that of the gas-liquid bubbling bed 20, while the circulation inlet 22 is located at the bottom of the bubbling bed 20.

[0049] In addition, a heat exchange unit 26 and a power unit 27 are provided on the circulation pipeline. The power unit 27 can be a pressure pump to provide circulation power to the circulation pipeline.

[0050] Additionally, the gas-liquid bubbling bed is equipped with a near-wall annular tube 31 located above the liquid-phase mixing bubble generator 21. The near-wall annular tube 31 is positioned above the liquid-phase mixing bubble generator 21, at a distance of 0.05 to 0.2 times the diameter of the bubbling bed, and is arranged at equal intervals along the wall. The inner diameter of the near-wall annular tube 31 is 0.01 to 0.05 times the inner diameter of the bubbling bed 20, and its length is 0.2 to 0.6 times the height of the bubbling bed 20. Small holes are evenly distributed on the tube wall, with a diameter ranging from 5 to 30 mm. Figure 3 As shown.

[0051] In addition, the present invention also provides a reaction method for a gas-liquid bubbling bed reactor, wherein the reaction method adopts the gas-liquid bubbling bed reactor described above.

[0052] Liquid feedstock enters from feedstock inlet 24 through circulation pipeline into the inlet straight pipe 1 of liquid phase mixing bubble generator 21 at the bottom of gas-liquid bubbling bed 20. The separated liquid obtained from subsequent separation processes (including unreacted liquid feedstock, intermediate products generating the target product, recovered solvent, or recovered catalyst solution, etc.) enters from separated liquid inlet 23 through the bubbling bed liquid chamber into the inlet pipe 5 of liquid phase mixing bubble generator 21. Air enters from gas inlet 22 through the bubbling bed gas chamber into the inlet pipe 11 of liquid phase mixing bubble generator 21, generating a microbubble-rich mixture of feedstock and separated liquid, which then enters the bubbling bed 20. The microbubble-rich mixture in the gas-liquid bubbling bed 20 moves upwards, and the wall effect is reduced by the near-wall ring pipe 31. The liquid feedstock reacts with the microbubble air to generate liquid-phase oxidation products and gas-phase products, releasing heat. The heated liquid-phase oxidation products enter the circulation pipeline, mix with the liquid feedstock, and after being cooled by heat exchange unit 26, they re-enter the bubbling bed 20 as circulating liquid.

[0053] After passing through the inlet straight pipe 2 and the converging section 3 of the liquid phase mixing bubble generator 20, the liquid velocity increases and it enters the throat straight section 4. The separated liquid enters the inlet pipe 5, and after being evenly distributed in the liquid phase chamber 6, it enters the throat straight section 4 from the liquid inlet 17. It is drawn into the throat straight section 4 by the high-speed, low-pressure liquid in the throat straight section 4 and is fully mixed with the liquid raw material. After being sheared and crushed by the high-speed liquid in the throat straight section 4 and pressurized and crushed by the expanding section 7, the liquid is mixed relatively evenly. The liquid phase vortex element 8 can generate a large number of small vortices from the high-speed liquid, improving the transfer efficiency. After being homogenized by the mixing element 10, a uniformly mixed liquid of liquid raw material and separated liquid is obtained. The homogeneous mixture then enters the outlet straight section 11 equipped with the accelerator 13. Under the action of the accelerator 13, it is depressurized and accelerated at the annular gap, resulting in rapid breakage. Air enters the inlet pipe 11, is evenly distributed through the gas phase chamber 12, and then rotates into the front of the outlet straight pipe 15 through the swirling air hole 9. It is entrained by the high-speed, low-pressure liquid in the annular gap and thoroughly mixed with the homogeneous mixture. After being sheared and broken by the high-speed liquid, the gas-liquid mixture entering the rear of the outlet straight pipe 15 is further broken by deceleration and pressurization. Under the action of the gas-liquid vortex component 14, the breakage becomes more intense and uniform, producing a liquid rich in microbubbles. Finally, after passing through the bubble-breaking plate 16, uniformly distributed microbubbles are obtained.

[0054] In addition, the liquid velocity in the inlet straight pipe 2 is greater than 1.0 m / s, the ratio of the liquid volume flow rate in the liquid inlet pipe 5 to that in the liquid inlet straight pipe 2 is 0.05~0.3, and the ratio of the gas volume flow rate in the gas inlet pipe 11 to that in the liquid inlet straight pipe 2 is 0.01~0.2.

[0055] In addition, the liquid velocity at the liquid inlet 17 is 0.01~0.1m / s, and the gas velocity through the swirling air hole 9 is 0.005~0.05m / s.

[0056] The following will describe embodiments and comparative examples of the gas-liquid bubbling bed reactor of this scheme.

[0057]

Example 1

[0058] o-Xylene enters the inlet straight pipe and tapering section of the liquid phase mixing bubble generator at the bottom of the gas-liquid bubbling bed through the circulation pipeline from the raw material inlet. The liquid velocity increases as it enters the throat straight section. The separated liquids such as o-xylene / o-methylbenzaldehyde / o-methylbenzyl alcohol / cobalt naphthenate obtained from the subsequent separation process enter the liquid inlet pipe of the liquid phase mixing bubble generator from the separation liquid inlet through the liquid chamber of the bubbling bed. It is entrained by the high-speed, low-pressure liquid in the throat straight section and enters the throat straight section, where it is fully mixed with the liquid raw material. After being sheared and crushed by the high-speed liquid in the throat straight section and pressurized and crushed by the tapering section, the liquid mixture is relatively uniform. The liquid phase vortex element can generate a large number of small vortices from the high-speed liquid, improving the transfer efficiency. After the homogenization effect of the mixing element, a uniformly mixed liquid of liquid raw material and separated liquid is obtained. The homogeneous mixture then enters the outlet straight section equipped with an accelerator. Under the action of the accelerator, it is depressurized and accelerated at the annular gap, causing further breakage. The gaseous feedstock air, after being evenly distributed in the gas phase chamber, rotates into the front of the outlet straight pipe through the swirling air holes. It is entrained by the high-speed, low-pressure liquid in the annular gap and thoroughly mixed with the homogeneous mixture. After being sheared and broken by the high-speed liquid, the gas-liquid mixture entering the rear of the outlet straight pipe is further broken by deceleration and pressurization. Under the action of the gas-liquid vortex component, the breakage is more intense and uniform, producing a liquid rich in microbubbles. Finally, after passing through the bubble-breaking plate, uniformly distributed microbubbles are obtained. The mixture of feedstock and separated liquid, which produces microbubbles, enters the bubble bed and moves upwards. The wall effect is reduced by the near-wall annular pipe. The liquid feedstock reacts with the microbubble air, generating liquid-phase oxidation products and gaseous products, releasing heat. The heated liquid-phase oxidation products enter the circulation pipeline, mix with the liquid feedstock, and after being cooled by the heat exchange unit, they re-enter the bubble bed as circulating liquid.

[0059] The inlet straight pipe has four bends at the inlet. The ratio of the cross-sectional area of ​​the throat straight section to that of the inlet straight pipe is 0.1. The liquid inlet annular gap spacing is 0.05 times the inner diameter of the throat straight section, and the liquid inlet taper angle is 30°. Four triangular plate-shaped liquid phase vortex elements are arranged circumferentially on the throat straight section and the taper section. The maximum height at the front end is 0.05 times the diameter of the throat straight section, and the maximum height at the rear end is 0.5 times the diameter of the throat straight section, respectively within the range of 0.5 times the length of the throat straight section and 0.2 times the length of the taper section. The mixing element on the throat straight section is a twisted plate, and the axial length of the mixing element is 0.6 times the length of the outlet straight pipe. Two layers of swirling air holes are provided, with four swirling air holes in each layer, and the taper angle of the swirling air holes is 30°. The accelerator is spherical-conical in shape. The ratio of the area of ​​the minimum annular gap between the accelerator and the outlet straight pipe to the cross-sectional area of ​​the outlet straight pipe is 0.08. Four plate-shaped gas-liquid vortex elements are arranged circumferentially at its tapered rear end. The maximum height of the plate-shaped gas-liquid vortex elements is 0.02 times the diameter of the outlet straight pipe. The ratio of liquid volumetric flow rate in the liquid inlet pipe to that in the liquid inlet straight pipe is 0.1, and the ratio of gas volumetric flow rate in the gas inlet pipe to that in the liquid inlet straight pipe is 0.2. The gas holdup in the gas-liquid bubbling bed is 0.3%, the average bubble diameter is 300 μm, and the single-pass yield of o-methylbenzoic acid is 62.2%. Detailed results are shown in Table 1.

[0060]

Example 2

[0061] The method is the same as in Example 1, except that the ratio of the cross-sectional area of ​​the throat straight section to the inlet straight pipe is 0.2. The results of the gas content, average bubble diameter and single-pass yield of o-methylbenzoic acid in the gas-liquid bubbling bed are detailed in Table 1.

[0062]

Example 3

[0063] The method is the same as in Example 1, except that the liquid inlet annular gap is 0.1 times the inner diameter of the straight section of the throat. The gas content, average bubble diameter and single-pass yield of o-methylbenzoic acid in the gas-liquid bubble bed are detailed in Table 1.

[0064]

Example 4

[0065] The method is the same as in Example 1, except that six triangular plate-shaped liquid phase vortex elements are arranged in the circumferential direction in the straight section and the gradually expanding section of the throat. The gas content, average bubble diameter and single-pass yield of o-methylbenzoic acid in the gas-liquid bubbling bed are detailed in Table 1.

[0066]

Example 5

[0067] The method is the same as in Example 1, except that the maximum height at the front end is 0.08 of the diameter of the straight section of the throat, and the maximum height at the rear end is 0.7 of the diameter of the straight section of the throat. The gas content, average bubble diameter and single-pass yield of o-methylbenzoic acid in the gas-liquid bubbling bed are detailed in Table 1.

[0068]

Example 6

[0069] The method is the same as in Example 1, except that the front and rear ends of the liquid phase vortex component are located within 0.7 of the length of the straight section of the throat and 0.4 of the length of the gradually expanding section, respectively. The gas holdup, average bubble diameter and single-pass yield of o-methylbenzoic acid in the gas-liquid bubbling bed are detailed in Table 2.

[0070]

Example 7

[0071] The method is the same as in Example 1, except that the mixing component in the straight section of the throat is a combination of twisted and elliptical plates. The results of gas content, average bubble diameter and single-pass yield of o-methylbenzoic acid in the gas-liquid bubbling bed are detailed in Table 2.

[0072]

Example 8

[0073] The method is the same as in Example 1, except that the axial length of the mixing component is 0.4 times the length of the outlet straight pipe. The gas holdup, average bubble diameter and single-pass yield of o-methylbenzoic acid in the gas-liquid bubbling bed are detailed in Table 2.

[0074]

Example 9

[0075] The method is the same as in Example 1, except that the ratio of the area of ​​the minimum annular gap of the accelerator to the cross-sectional area of ​​the outlet straight pipe is 0.05. The results of gas holdup, average bubble diameter and single-pass yield of o-methylbenzoic acid in the gas-liquid bubbling bed are detailed in Table 2.

[0076]

Example 10

[0077] The method is the same as in Example 1, except that the rear tapering section is provided with 6 plate-shaped gas-liquid vortex elements along the circumference. The gas content, average bubble diameter and single-pass yield of o-methylbenzoic acid in the gas-liquid bubbling bed are detailed in Table 2.

[0078]

Example 11

[0079] The method is the same as in Example 1, except that the maximum height of the sheet-like gas-liquid vortex component is 0.03 of the diameter of the outlet straight pipe. The gas holdup, average bubble diameter and single-pass yield of o-methylbenzoic acid in the gas-liquid bubbling bed are detailed in Table 3.

[0080]

Example 12

[0081] The method is the same as in Example 1, except that the ratio of gas volume flow rate in the inlet pipe to liquid volume flow rate in the inlet straight pipe is 0.2. The results of gas holdup, average bubble diameter and single-pass yield of o-methylbenzoic acid in the gas-liquid bubble bed are detailed in Table 3.

[0082]

Comparative Example 1

[0083] The method is the same as in Example 1, except that no liquid phase vortex component is set. The gas holdup, average bubble diameter and single-pass yield of o-methylbenzoic acid in the gas-liquid bubbling bed are detailed in Table 3.

[0084] [Comparative Example 2]

[0085] The method is the same as in Example 1, except that no gas-liquid vortex component is set. The gas holdup, average bubble diameter and single-pass yield of o-methylbenzoic acid in the gas-liquid bubbling bed are detailed in Table 3.

[0086] [Comparative Example 3]

[0087] The results of the gas holdup, average bubble diameter and single-pass yield of o-methylbenzoic acid in the gas-liquid bubble bed using the existing Venturi bubble generator and gas-liquid bubbling device are detailed in Table 3.

[0088] Table 1

[0089]

[0090] Table 2

[0091]

[0092] Table 3

[0093]

[0094] This invention increases the gas-liquid contact area and liquid-liquid mixing efficiency, strengthens the transfer process, improves the reaction rate, effectively reduces the reaction time, and significantly improves the product yield and economy of o-methylbenzoic acid by using a bubble generator, a gas-liquid bubbling reactor, and a reaction method.

[0095] The preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various specific technical features in any suitable manner. To avoid unnecessary repetition, the present invention will not describe the various possible combinations separately. However, these simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A liquid-phase mixing bubble generator, characterized in that, The liquid phase mixing bubble generator includes a venturi tube (1) and an outlet straight pipe (15). The venturi tube (1) includes a tapering section (3), a throat straight section (4), and a diverging section (7). The outlet straight pipe (15) is connected to the diverging section (7). A liquid inlet (17) penetrating the pipe wall is provided on the throat straight section (4). A swirling air hole (9) penetrating the pipe wall at an angle to the radial direction is provided on the outlet straight pipe (15). The liquid inlet (17) is an annular gap. The liquid phase mixing bubble generator includes a liquid phase chamber (6) surrounding the throat straight section (4) at the liquid inlet (17). The liquid phase mixing bubble generator includes an accelerator (13) disposed in the outlet straight pipe (15) and located at the swirling gas hole (9). An annular gap is formed between the accelerator (13) and the inner circumferential surface of the outlet straight pipe (15). The accelerator (13) includes a tapered portion, and a sheet-like gas-liquid vortex element (14) is disposed on the tapered portion. The liquid phase mixing bubble generator includes sheet-shaped liquid phase vortex elements (8) disposed in the throat straight section (4) and the gradually expanding section (7). The maximum height of the front end of the liquid phase vortex element (8) is 0.05~0.01 of the inner diameter of the throat straight section (4), and the maximum height of the rear end of the liquid phase vortex element (8) is 0.5~1.0 of the inner diameter of the throat straight section (4). The liquid phase vortex element (8) is located within the range of 0.5~1 of the length of the throat straight section (4) and 0~0.5 of the length of the gradually expanding section (7). 2~20 pieces of the liquid phase vortex element (8) are disposed in the throat straight section (4) and the gradually expanding section (7) in the circumferential direction.

2. The liquid-phase mixing bubble generator according to claim 1, characterized in that, The cross-section of the liquid inlet (17) gradually narrows along the flow direction.

3. The liquid-phase mixing bubble generator according to claim 1, characterized in that, The swirling air hole (9) penetrates the pipe wall along the tangential direction of a concentric circle with a radius smaller than the inner circumference of the outlet straight pipe (15).

4. The liquid-phase mixing bubble generator according to claim 1, characterized in that, The liquid phase mixing bubble generator includes a gas phase chamber (12) with the outlet straight pipe (15) at the swirling gas hole (9).

5. The liquid-phase mixing bubble generator according to claim 1, characterized in that, The liquid phase mixing bubble generator includes a sheet-like mixing element (10) disposed in the throat straight section (4) and located upstream of the swirling air hole (9).

6. The liquid-phase mixing bubble generator according to claim 1, characterized in that, The liquid phase mixing bubble generator includes a mesh or grid-like bubble-breaking plate (16) disposed at one end of the outlet straight pipe (15) away from the diffuser section (7).

7. The liquid-phase mixing bubble generator according to claim 1, characterized in that, The liquid phase mixing bubble generator includes an inlet straight pipe (2) connected to the tapered section (3).

8. A gas-liquid bubbling bed reactor, characterized in that, The gas-liquid bubbling bed reaction device includes a bubbling bed (20), a circulation pipeline, and a liquid phase mixing bubble generator (21) according to any one of claims 1-7 disposed at the lower part of the bubbling bed (20). The bubbling bed (20) is provided with a gas phase outlet (30) at the top, a liquid phase outlet (29) at the side, a separation liquid inlet (23) connected to the liquid inlet (17), a gas phase inlet (22) connected to the swirling gas hole (9), a circulation outlet (25) at the top, and a circulation inlet (28) at the bottom. The circulation pipeline is connected to the circulation inlet (28) and the circulation outlet (25), and a raw material inlet (24) is connected to the circulation pipeline.

9. The gas-liquid bubbling bed reactor according to claim 8, characterized in that, The circulation pipeline is equipped with a heat exchange unit (26) and a power component (27).

10. The gas-liquid bubbling bed reactor according to claim 8, characterized in that, The gas-liquid bubbling bed is provided with a near-wall ring pipe (31) located on the upper side of the liquid phase mixing bubble generator (21).

11. A reaction method for a gas-liquid bubbling bed reactor, characterized in that, The reaction method employs the gas-liquid bubbling bed reaction apparatus as described in any one of claims 8-10.

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