A multi-stage micro-interface wastewater treatment device based on shock wave coupled liquid film shearing

Abstract

This invention relates to the field of wastewater treatment technology, and in particular to a multi-stage micro-interface wastewater treatment device based on shock wave coupled liquid film shearing, comprising: an outer tube for through which a high-speed gas flow carrying an oxidant passes, the inner wall of which protrudes and forms a plurality of spaced Venturi units; an injection pipe located inside the outer tube for supplying liquid, the injection pipe having a guide ring, the guide ring having an overflow hole for allowing the liquid inside the injection pipe to flow out, the guide ring being used to allow the liquid to diffuse and form a liquid film; and a tail-end treatment and recovery mechanism for treating the gas-liquid mixture discharged from the outer tube, the input end of the tail-end treatment and recovery mechanism being connected to the output end of the outer tube. By directly atomizing wastewater into micron-sized aerosols and reacting them with ozone at the interface, the toxic effects of high-salt environments on microorganisms are fundamentally avoided, and the chemical oxygen demand of high-concentration organic wastewater can be significantly reduced stably.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment technology, and in particular to a multi-stage micro-interface wastewater treatment device based on shock wave coupled liquid film shearing. Background Technology

[0002] In industries such as chemical, pharmaceutical, and dyeing, wastewater containing high concentrations of inorganic salts (such as sodium chloride and sodium sulfate) and recalcitrant organic compounds (such as phenols and antibiotics) is frequently generated. Traditional treatment methods suffer from the following drawbacks: Advanced oxidation processes (AOPs) are costly: for example, the Fenton process requires the addition of large amounts of reagents and produces a large amount of iron sludge; ozone oxidation has low gas-liquid mass transfer efficiency and low ozone utilization.

[0003] Evaporation method has high energy consumption: direct evaporation crystallization has extremely high energy consumption, and organic matter can affect the quality of crystallized salt.

[0004] Electrochemical electrodes are prone to passivation: In high-salt environments, electrodes are extremely susceptible to scaling or poisoning.

[0005] Recent studies have shown that the gas-liquid interface of micron-sized droplets possesses a self-generating field as high as 10⁹ V / m, which can activate chloride ions to generate free radicals. However, existing spray devices (such as ordinary pressure nozzles) produce droplets with a wide size distribution (typically >50 μm), small interfacial surface area, and a tendency to coalesce, making it difficult to industrialize the micro-interface oxidation effect. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to overcome the problem that the droplet particle size distribution of the spray device (such as ordinary pressure nozzle) is wide (usually >50μm), the interface specific surface area is small, and droplet aggregation is easy to occur, which makes it difficult to industrialize the micro-interface oxidation effect. The present invention provides a multi-stage micro-interface wastewater treatment device based on shock wave coupled liquid film shear.

[0007] The technical solution adopted by this invention to solve its technical problem is: a multi-stage micro-interface wastewater treatment device based on shock wave coupled liquid film shearing, comprising: The outer tube is used to allow a high-speed gas flow carrying the oxidant to pass through, and the inner wall of the outer tube has several venturi units that are spaced out. The injection tube is located inside the outer tube and is used to supply liquid. The injection tube has a guide ring and an overflow hole for the liquid to flow out of the injection tube. The guide ring is used to allow the liquid to diffuse and form a liquid film. The system also includes a tail-end treatment and recovery mechanism for treating the gas-liquid mixture discharged from the outer pipe. The input end of the tail-end treatment and recovery mechanism is connected to the output end of the outer pipe. It utilizes a pure physicochemical process of shock wave coupled liquid film shearing to replace biological treatment. It has extremely strong tolerance to wastewater with a salt content as high as 3%. By directly atomizing the wastewater into micron-sized aerosols and reacting them with ozone at the interface, it fundamentally avoids the toxic effects of high-salt environments on microorganisms. It can stably and significantly reduce the chemical oxygen demand of high-concentration organic wastewater, creating the preconditions for subsequent compliant discharge or biochemical treatment.

[0008] To address the problem that existing Venturi devices rely solely on throat acceleration, resulting in insufficient energy utilization and a lack of synergistic effects in secondary deep droplet fragmentation and shock-induced oxidation, a further Venturi unit is proposed, comprising a contraction section, a throat, and an expansion section connected sequentially from the input end to the output end of the outer tube. The contraction section contracts inward from the input end to the output end of the outer tube, while the expansion section expands outward from the input end to the output end of the outer tube.

[0009] To address the issues of limited single-stage processing capacity and mismatch between the liquid film position and the shock wave generation position, which leads to wasted airflow energy or insufficient liquid film entry into the shock wave core region, a transition section is further formed between the Venturi units of the outer tube. The flow guide ring and the Venturi unit are in one-to-one correspondence. The side of the flow guide ring near the input end of the outer tube extends into the adjacent transition section, and the side of the flow guide ring near the output end of the outer tube extends into the front part of the expansion section of the corresponding Venturi unit.

[0010] To address the issues of uneven liquid film formation, high flow resistance, and susceptibility to being instantly broken by high-speed airflow during the injection process, leading to film formation failure, a further improvement is made to include a guide ring that expands outward from the input end of the outer tube towards the output end.

[0011] To address the issue of flow channel blockage or the inability of throat air velocity to reach the speed of sound caused by improper expansion angle of the guide ring, the design further includes a conical structure for the guide ring, with a cone angle of 15°-30°.

[0012] To address the issue of random tearing of the liquid film upon detachment from the solid wall, resulting in a wide initial droplet size distribution and the inability of excessively large droplets to participate in the micro-interface reaction, a further design includes a separation point located at an acute angle on the tail edge of the guide ring near the output end of the outer tube.

[0013] To address the problem that improperly positioned injection holes can cause water flow to be disturbed by airflow and fail to adhere to the wall, or that the liquid is prematurely dispersed and unable to form a complete liquid film, a further improvement is made by positioning the overflow hole at the front end of the outer wall of the guide ring.

[0014] To address the issues of incomplete separation of the gas-liquid mixture after treatment, and the resulting corrosion of pipelines or water ingress failure of the ozone exhaust gas destroyer due to entrainment of salt droplets in the gas phase, a tail-end treatment and recovery mechanism is further included, comprising a cyclone separator and a demister. The input end of the cyclone separator is connected to the output end of the outer pipe. The top surface of the cyclone separator has a gas phase output end, and the bottom surface of the cyclone separator has a liquid phase output end. The gas phase output end of the cyclone separator is connected to the input end of the demister, and the top surface of the demister has a gas phase output end.

[0015] The beneficial effects of this invention are as follows: This invention provides a multi-stage micro-interface wastewater treatment device based on shock wave coupled liquid film shearing. This invention utilizes the strong tolerance of shearing and shock wave oxidation to wastewater with a salt content as high as 3%. By directly atomizing the wastewater into micron-sized aerosols and reacting it with ozone at the interface, the toxic effects of high-salt environments on microorganisms are fundamentally avoided. This invention can stably and significantly reduce the chemical oxygen demand of high-concentration organic wastewater, creating the preconditions for subsequent discharge or biochemical treatment to meet standards. This invention uses a flow guide ring to separate and supersonic airflow shearing to instantly pulverize the liquid film into a group of micron-sized droplets, resulting in a geometric increase in the gas-liquid contact surface area. In particular, by utilizing the shock wave effect generated by the Venturi expansion section, the drastic pressure and density changes before and after the shock wave not only cause secondary tearing of the droplets but also induce water molecules to generate transient free radicals, forming a synergistic oxidation mechanism with ozone. Attached Figure Description

[0016] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0017] Figure 1 This is a schematic diagram of the structure of the present invention; Figure 2 This is a schematic diagram of the structure of the outer tube of the present invention (the arrows in the diagram indicate the direction of fluid flow). Figure 3 This is the present invention. Figure 2 A magnified schematic diagram of a portion of the structure (the arrows in the diagram indicate the direction of fluid flow).

[0018] In the diagram: 1. Outer tube, 11. Venturi unit, 111. Contraction segment, 112. Throat, 113. Expansion segment, 12. Transition segment; 2. Injection pipe; 21. Guide ring; 211. Overflow hole; 212. Separation point; 3. Tail-end treatment and recycling mechanism; 31. Cyclone separator; 32. Demister. Detailed Implementation

[0019] The present invention will now be described in further detail with reference to the accompanying drawings. These drawings are simplified schematic diagrams, illustrating only the basic structure of the invention, and therefore only show the components relevant to the invention.

[0020] like Figure 1 This is a schematic diagram of the structure of the present invention, a multi-stage micro-interface wastewater treatment device based on shock wave coupled liquid film shearing, comprising: The outer tube 1 is used to allow a high-speed gas flow carrying oxidant to pass through. Several Venturi units 11 are formed on the inner wall of the outer tube 1 at intervals. The Venturi unit 11 includes a contraction section 111, a throat 112 and an expansion section 113 connected in sequence from the input end to the output end of the outer tube 1. The contraction section 111 contracts inward from the input end to the output end of the outer tube 1, and the expansion section expands outward from the input end to the output end of the outer tube 1. By defining the connection relationship between the contraction section 111, the throat and the expansion section 113, the gas flow is ensured to accelerate to supersonic speed and generate a shock wave. When the liquid film passes through the shock wave surface in the expansion section 113, it is torn by a sudden pressure change, which induces a micro-interface oxidation reaction, significantly improving the instantaneous reaction rate and utilization depth of ozone. A transition section 12 is formed between the Venturi units 11 of the outer tube 1.

[0021] In the embodiment, the outer tube 1 is made of stainless steel or corrosion-resistant alloy, and there are 3-5 Venturi units 11 arranged in sequence inside the outer tube, and the wastewater is treated in sequence.

[0022] like Figure 2 , 3 As shown, the injection tube 2 is located inside the outer tube 1 and is used for supplying liquid. The injection tube 2 has a guide ring 21 with an overflow hole 211 for the liquid to flow out of the injection tube 2. The guide ring 21 is used to allow the liquid to diffuse and form a liquid film. The guide ring 21 corresponds to the Venturi unit 11. The side of the guide ring 21 near the input end of the outer tube 1 extends into the adjacent transition section 12 or the contraction section 111 of the corresponding Venturi unit 11. The side of the guide ring 21 near the output end of the outer tube 1 extends into the front part of the expansion section 113 of the corresponding Venturi unit 11. The front end of the guide ring 21 extends into the transition section 12 to ensure stable water supply, and the tail end extends into the front part of the expansion section 113 to ensure that the liquid film separation point 212 is accurately located upstream of the shock wave, so that the droplets pass through the shock wave with the airflow at the moment of formation, maximizing the utilization of the shock wave shear energy.

[0023] The flow guide ring 21 expands outward from the input end to the output end of the outer tube 1. This structure follows the airflow direction and uses the airflow adhesion effect to guide the liquid to spread smoothly into a film, which reduces the airflow resistance and prevents the liquid from flowing back or splashing under high pressure difference.

[0024] The guide ring 21 has a conical structure and the cone angle of the guide ring 21 is 15°-30°. This angle range can maintain the stable flow of the liquid film while forming the smallest contraction section in the annular gap, ensuring that the Mach number of the airflow in the throat reaches 1.0 accurately, and providing the necessary aerodynamic conditions for the expansion section 113 to generate a stable shock wave.

[0025] The tail edge of the guide ring 21 near the output end of the outer tube 1 is the separation point 212. The separation point 212 is an acute angle structure. Utilizing the principle of boundary layer separation in fluid mechanics, it causes the liquid film to be precisely and uniformly cut and peeled off by the high-speed airflow at the sharp edge, ensuring that the droplets generated by the first-stage atomization are small in size and concentrated in distribution, providing an ideal precursor for the subsequent secondary shock wave breakup.

[0026] The overflow hole 211 is located at the front end of the outer wall of the guide ring 21. This area is at the beginning of the airflow boundary layer and the leeward region is relatively stable. After the liquid overflows from this point, it can immediately spread to the downstream conical surface by means of the wall adhesion effect of the airflow, thus avoiding the droplets being blown away from the wall surface before forming a film.

[0027] And a tail-end treatment and recovery mechanism 3, which is used to treat the gas-liquid mixture discharged from the outer pipe 1, with the input end of the tail-end treatment and recovery mechanism 3 connected to the output end of the outer pipe 1.

[0028] like Figure 1 As shown, the tail-end treatment and recovery mechanism 3 includes a cyclone separator 31 and a demister 32. The input end of the cyclone separator 31 is connected to the output end of the outer pipe 1. The top surface of the cyclone separator 31 has a gas phase output end, and the bottom surface of the cyclone separator 31 has a liquid phase output end. The gas phase output end of the cyclone separator 31 is connected to the input end of the demister 32. The top surface of the demister 32 has a gas phase output end. The two-stage series combination of the cyclone separator 31 and the demister 32 is adopted. The cyclone separator 31 uses centrifugal force to efficiently remove more than 90% of large liquid particles. The post-demister 32 intercepts and captures submicron-sized salt spray aerosols with a particle size of less than 5 micrometers, ensuring that the discharged gas is dry and clean, protecting the safety of subsequent tail gas treatment facilities, and ensuring complete gas-liquid separation. It not only recovers the treated water but also prevents chlorine-containing aerosols from escaping into the environment.

[0029] Treatment process: A multi-stage micro-interface wastewater treatment device based on shock wave coupled liquid film shear is used to treat chemical wastewater with COD of 5000 mg / L and salt content of 3%. The compressed air source is started, and compressed air mixed with ozone (concentration of 50 mg / L) is introduced into the inlet of the outer pipe 1. The inlet pressure is adjusted, and the airflow is accelerated by the contraction section 111 of the Venturi unit 11 to ensure that the airflow speed reaches the speed of sound in the throat region 112, and a supersonic flow field and a stable shock wave surface are formed in the subsequent expansion section 113. Start the water pump to press the chemical wastewater to be treated into the central injection pipe 2. Under pressure, the wastewater overflows evenly from the overflow hole 211 at the front end of the outer wall of the guide ring 21. Under the sweeping and traction of the high-speed airflow in the annular throat, the wastewater spreads into a uniform and high-speed flowing thin liquid film along the conical surface of the guide ring 21. When the flowing liquid film slides to the acute-angle separation point 212 at the tail edge of the guide ring 21, it is subjected to instantaneous shearing and stripping by the sonic or supersonic airflow within the annular throat 112. The liquid film is shattered to form an initial micron-sized aerosol droplet cluster. The high-speed airflow carrying the droplets then rushes into the expansion section 113 and crosses the shock wave surface. During this process, under the triple action of strong mechanical shearing, interfacial electric field (spontaneously generated), and ozone, the organic matter in the wastewater is rapidly oxidized and decomposed. After being processed by the first-stage Venturi unit 11, the gas-liquid mixture flows into the transition section 12. Some droplets collide and agglomerate, resulting in an increase in particle size. When the mixed fluid enters the second-stage Venturi unit 11, the corresponding guide ring 21 supplies liquid again to form a new liquid film. The next shock wave is used to force the agglomerated and enlarged droplet group to break up again. This process is repeated in the second and third-stage Venturi units 11 to ensure that the organic matter in the wastewater can fully contact and react with ozone in the multi-stage micro-interface environment. After treatment, the high-speed mixed-phase fluid enters the tail treatment and recovery mechanism 3 from the output end of the outer pipe 1. It first enters the cyclone separator 31. Under the action of centrifugal force, more than 90% of the treated liquid is thrown against the wall and discharged from the bottom liquid phase output end by gravity. At this time, the liquid chemical oxygen demand has been significantly reduced. It can be recycled or discharged into the subsequent biochemical system as appropriate. The separated gas carries a small amount of fine mist droplets into the top demister 32. The demister 32 has a baffle or wire mesh structure to further capture residual mist droplets with a particle size of less than 5 micrometers. Finally, the clean exhaust gas is treated by the ozone destroyer and discharged in compliance with standards.

[0030] Preferably, a catalyst that can promote ozone oxidation of organic matter is loaded on the surface of the guide ring, so that the liquid film can rapidly decompose a portion of the organic matter on the surface of the catalyst.

[0031] The supported catalysts are common transition metal oxides such as manganese, iron, cobalt, and copper.

[0032] The device of this invention utilizes a three-stage coupling mechanism of "liquid film pre-expansion - pneumatic shearing - shock wave crushing" to overcome the shortcomings of traditional nozzles, such as large atomization particle size, easy clogging, and low reaction efficiency.

[0033] First stage: Formation and pre-expansion of liquid film: The wastewater to be treated enters the interior of the inverted conical guide ring 21 through the central injection pipe 2, and flows out through the overflow hole 211 opened on the windward cone surface.

[0034] Physical mechanism: Under the purging of high-speed airflow and the action of fluid viscosity (Coanda effect), the wastewater no longer exists in the form of a "water column", but flows closely along the outer wall surface of the inverted conical guide ring and is forced to flatten into a uniform liquid film with a thickness of only micrometers (10-100μm).

[0035] Second stage: Primary pneumatic shearing and breaking: When the liquid film flows along the conical surface to the sharp tail edge of the inverted conical guide ring 21, it breaks away from the constraint of the solid wall. At this time, the liquid film is exactly at the throat 112 of the corrugated outer tube.

[0036] Physical mechanism: In the throat, the airflow is accelerated to subsonic or sonic speed (Mach ≈ 1), and a huge relative velocity difference is generated between the gas and liquid. Under the action of strong aerodynamic shear force, the liquid film undergoes Kelvin-Helmholtz instability (K-HInstability), is instantly peeled off and torn, undergoes primary atomization, and breaks into fine liquid filaments and droplets.

[0037] Third stage: Supersonic shock wave deep crushing: The droplets after primary atomization enter the expansion section 113 of the corrugated outer tube 1 with the airflow.

[0038] Physical mechanism: Laval effect: The expansion section 113 constitutes the diffuser of the Laval nozzle, where the airflow continues to accelerate to supersonic speeds (Mach>1).

[0039] Shock wave generation: Due to the presence of back pressure, the supersonic airflow undergoes a sudden change at a certain point in the expansion section 113, generating one or more strong normal shock waves or oblique shock waves.

[0040] Droplet "collision": The shock wave surface is equivalent to a "high-pressure air wall". When a high-speed droplet passes through the shock wave surface, the environmental pressure increases instantaneously (experiencing an extremely large pressure gradient), and the droplet undergoes violent deformation and implosion (cavitation effect), resulting in secondary fragmentation. The particle size is further pulverized into nano- or submicron-sized aerosols.

[0041] Fourth stage: Micro-interface enhanced oxidation reaction: In the shock wave zone and subsequent flow channels, the ultrafine aerosol reacts violently with ozone in the gas phase.

[0042] Chemical mechanism: Specific surface area surge: The extremely small particle size means that the specific surface area of ​​gas-liquid contact increases geometrically, completely eliminating gas-liquid mass transfer resistance.

[0043] Interfacial electric field effect: The high-speed crushing process causes the droplet surface to become electrostatic, forming a micro-interfacial self-generated electric field of up to 108-109 V / m. This electric field can reduce the reaction activation energy and directionally activate inorganic salts (such as Cl-) in wastewater, causing them to be converted in situ into active chlorine free radicals (Cl·, Cl2·-).

[0044] Synergistic oxidation: Ozone molecules, hydroxyl radicals and active chlorine radicals work synergistically inside and on the surface of microdroplets to rapidly mineralize recalcitrant organic matter into carbon dioxide and water.

[0045] Based on the above-described preferred embodiments of the present invention, and through the foregoing description, those skilled in the art can make various changes and modifications without departing from the inventive concept. The technical scope of this invention is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. A multi-stage micro-interface wastewater treatment device based on shock wave coupled liquid film shearing, characterized in that, include: The outer tube (1) is used to allow a high-speed gas flow carrying oxidant to pass through, and the inner wall of the outer tube (1) is formed with a number of spaced Venturi units (11). The injection tube (2) is located inside the outer tube (1). The injection tube (2) is used to supply liquid. The injection tube (2) has a guide ring (21). The guide ring (21) has an overflow hole (211) for the liquid in the injection tube (2) to flow out. The guide ring (21) is used to make the liquid diffuse to form a liquid film. And a tail-end treatment and recovery mechanism (3) for treating the gas-liquid mixture discharged from the outer pipe (1), wherein the input end of the tail-end treatment and recovery mechanism (3) is connected to the output end of the outer pipe (1).

2. The multi-stage micro-interface wastewater treatment device based on shock wave coupled liquid film shearing as described in claim 1, characterized in that: The Venturi unit (11) includes a contraction section (111), a throat (112), and an expansion section (113) connected sequentially from the input end of the outer tube (1) to the output end. The contraction section (111) contracts inward from the input end of the outer tube (1) to the output end, and the expansion section expands outward from the input end of the outer tube (1) to the output end.

3. The multi-stage micro-interface wastewater treatment device based on shock wave coupled liquid film shearing as described in claim 2, characterized in that: A transition section (12) is formed between the Venturi units (11) of the outer tube (1). The flow guide ring (21) and the venturi unit (11) correspond one-to-one. The side of the flow guide ring (21) near the input end of the outer tube (1) extends into the adjacent transition section (12). The side of the flow guide ring (21) near the output end of the outer tube (1) extends into the front part of the expansion section (113) of the corresponding venturi unit (11).

4. The multi-stage micro-interface wastewater treatment device based on shock wave coupled liquid film shearing as described in claim 1, characterized in that: The flow guide ring (21) expands outward from the input end of the outer tube (1) towards the output end.

5. The multi-stage micro-interface wastewater treatment device based on shock wave coupled liquid film shearing as described in claim 4, characterized in that: The guide ring (21) has a conical structure, and the cone angle of the guide ring (21) is 15°-30°.

6. The multi-stage micro-interface wastewater treatment device based on shock wave coupled liquid film shearing as described in claim 1, characterized in that: The tail edge of the guide ring (21) near the output end of the outer tube (1) is the separation point (212), and the separation point (212) is an acute angle structure.

7. The multi-stage micro-interface wastewater treatment device based on shock wave coupled liquid film shearing as described in claim 1, characterized in that: The overflow hole (211) is located at the front end of the outer wall of the guide ring (21).

8. The multi-stage micro-interface wastewater treatment device based on shock wave coupled liquid film shearing as described in claim 1, characterized in that: The tail-end processing and recovery mechanism (3) includes a cyclone separator (31) and a demister (32). The input end of the cyclone separator (31) is connected to the output end of the outer tube (1). The top surface of the cyclone separator (31) has a gas phase output end, and the bottom surface of the cyclone separator (31) has a liquid phase output end. The gas phase output end of the cyclone separator (31) is connected to the input end of the demister (32). The top surface of the demister (32) has a gas phase output end.

Images