Method for removal of new pollutants by hydrodynamic cavitation assisted by enhanced mass transfer high multiphase flow

Abstract

This invention relates to the field of water treatment technology, specifically to a method for removing new pollutants using hydraulic cavitation in a high-speed multiphase flow with enhanced mass transfer. The method includes the following steps: pumping pretreated wastewater containing new pollutants to the inlet of a reverse shear mechanism, where cavitation generates a primary fluid with high-energy-density hydroxyl radicals; conveying the primary fluid to a connecting pipe, where it is sufficiently agitated and mixed with the fluid ejected from a Venturi tube to generate a high-speed multiphase intermediate fluid; conveying the intermediate fluid to the inlet of a forward shear mechanism, where cavitation generates a final fluid with a large number of uniformly distributed hydroxyl radicals; detecting the target pollutant concentration in the final fluid, and repeating the above steps or adding multi-stage cavitation generating components until the target pollutant concentration is less than or equal to a preset concentration value. This improves the hydraulic cavitation effect, increases the outlet free radical energy density, and enhances the mass transfer between pollutants and free radicals in the wastewater.

Description

Technical Field

[0001] This invention relates to the field of water treatment technology, and more specifically, to a method for removing new pollutants by hydraulic cavitation in high-speed multiphase flow with assisted mass transfer enhancement. Background Technology

[0002] With rapid industrial development and increasingly frequent human activities, the problem of emerging pollutants in wastewater is becoming increasingly prominent. These emerging pollutants typically include perfluorinated or polyfluorinated compounds, microplastics, endocrine disruptors, pharmaceuticals, and personal care products. These emerging pollutants are characterized by their diversity, wide range of sources, low environmental concentrations, but significant harmful effects. In the past, wastewater treatment primarily focused on removing conventional pollutants such as chemical oxygen demand (COD), ammonia nitrogen, and total phosphorus. However, the emergence of these emerging pollutants poses a potential threat to the environment and human health. They may disrupt the endocrine system of organisms, affecting reproduction and development; they are bioaccumulative and can be transferred through the food chain; and they may even trigger serious diseases such as cancer.

[0003] Treatment methods for novel pollutants in wastewater are mainly classified into four categories: advanced oxidation technologies, adsorption technologies, membrane separation technologies, and biological treatment technologies. Adsorption technologies, represented by activated carbon adsorption and ion exchange resins, and membrane separation technologies, represented by reverse osmosis and nanofiltration, only enrich the novel pollutants; the adsorbent material or concentrate still requires further treatment. Novel pollutants in wastewater are diverse, and biological treatment technologies require screening for highly efficient, multifunctional degrading strains. Furthermore, many pollutants in wastewater are often highly toxic, and the adaptability and stability of microorganisms need to be improved. Advanced oxidation technologies degrade novel pollutants by generating highly oxidizing reactive species, exhibiting strong oxidation capacity and fast reaction rates. However, for novel pollutants with low concentrations and high stability in wastewater, low-consumption and high-efficiency advanced oxidation technologies still require further development.

[0004] Hydraulic cavitation is an advanced oxidation technology. Its principle is to use pressure drop to release gas dissolved in fluid to generate a large number of cavitation bubbles. When the cavitation bubbles flow with the fluid to the high-pressure area, their volume will shrink rapidly until they collapse, and local high temperature and high pressure will be generated in a very small space around them. Water molecules are broken down into free radicals such as ·OH under the extreme environment of high temperature and high pressure, thereby causing a series of oxidation reactions.

[0005] Existing hydraulic cavitation methods for wastewater treatment are mostly based on venturi tubes or orifice plates, resulting in low cavitation intensity, small flow rate, and poor reaction effect. Summary of the Invention

[0006] The objectives of this invention include, for example, providing a method for removing new pollutants by hydraulic cavitation in high-speed multiphase flow with enhanced mass transfer, which can improve the hydraulic cavitation effect, increase the energy density of free radicals at the outlet, and enhance the mass transfer effect between pollutants and free radicals in wastewater.

[0007] The embodiments of the present invention can be implemented as follows:

[0008] In a first aspect, the present invention provides a method for removing new pollutants by hydraulic cavitation in high-speed multiphase flow with assisted enhanced mass transfer. This method is based on a cavitation generating device, which includes multi-stage cavitation generating components arranged in series. Each stage of the cavitation generating component includes a reverse shearing mechanism, a connecting pipe, and a forward shearing mechanism connected in sequence. The connecting pipe is equipped with an array of venturi tubes. The method includes at least the following steps:

[0009] The pretreated wastewater containing new pollutants is pumped to the inlet of the reverse shear mechanism. The reverse shear mechanism is used to accelerate and pressurize the wastewater to form a high-speed multiphase flow. Cavitation occurs at the outlet of the reverse shear mechanism to generate a primary fluid with high energy density hydroxyl radicals.

[0010] The initial fluid is transported to a connecting pipe with an array of Venturi tubes, where it is fully disturbed and mixed with the fluid ejected from the Venturi tubes to generate a high-speed multiphase mid-section fluid.

[0011] The intermediate fluid is transported to the inlet of the forward shearing mechanism, where the forward shearing mechanism further pressurizes the intermediate fluid, and cavitation occurs at the outlet of the forward shearing mechanism to generate a final fluid with a large number of uniformly distributed hydroxyl radicals.

[0012] The concentration of the target pollutant in the final fluid is detected; if the concentration of the target pollutant is greater than the preset concentration value, the above steps are repeated or a multi-stage cavitation generation component is added until the concentration of the target pollutant is less than or equal to the preset concentration value.

[0013] In an optional implementation, the hydraulic cavitation effect is evaluated by the following formula:

[0014]

[0015] In the formula, C v P is the dimensionless hydraulic cavitation number, P2 is the fully recovered downstream pressure, and P v v0 is the vapor pressure of the wastewater to be treated, v0 is the velocity at the outlet of the cavitation generating structure, and ρ is the density of the wastewater to be treated.

[0016] Hydraulic cavitation number C v When the value is less than 1, spatialization will occur, C v The smaller the value, the better the cavitation effect, and the more cavitation bubbles are generated; C v The value ranges from 0.1 to 0.3.

[0017] In an optional implementation, v0 is adjusted by the pump flow rate and the rotational speed and number of stages of the cavitation generator structure;

[0018] P2 is regulated by the inlet pressure of the cavitation generator structure and the diameter of the connecting pipe;

[0019] P v The amount of dissolved gas in the wastewater to be treated is adjusted by changing the fluid ejected through a venturi tube.

[0020] Thus achieving C v Optimal value.

[0021] In an optional embodiment, the reverse shearing mechanism is a rotary contraction structure in which wastewater flows radially and is ejected axially after rotary contraction to generate high-energy-density hydroxyl radicals.

[0022] In an optional embodiment, the forward shearing mechanism is a rotary diffusion structure, in which wastewater flows in axially and diffuses radially around the rotary acceleration port to generate a large number of uniformly distributed hydroxyl radicals.

[0023] In an optional embodiment, the total jet flow rate of the plurality of Venturi tubes is 5%-10% of the wastewater flow rate in the connecting pipe;

[0024] The flow velocity at the nozzle of the venturi tube is 0.6-0.8 times the flow velocity of the wastewater in the connecting pipe;

[0025] The angle between the spray direction of the venturi tube and the flow direction of the wastewater is 10-60°.

[0026] In an optional embodiment, the fluid injected into the connecting pipe by the venturi tube can be at least one of a liquid, a gas, or a mixture.

[0027] The liquid sprayed by the venturi tube includes the circulating effluent and process water treated by this method;

[0028] The gas injected by the Venturi tube includes any oxidizing gas such as air, oxygen, or ozone;

[0029] The mixture injected by the venturi tube includes any combination of the liquid and gas mentioned above.

[0030] In an optional embodiment, a fluid-permeable spacer is arranged upstream of the venturi tube within the inner wall of the connecting pipe.

[0031] The wastewater forms a vortex after flowing through the surrounding fluid, which can enhance the degree of turbulence of the wastewater and increase the collision effect with the fluid jetted from the Venturi tube.

[0032] In an optional embodiment, in a multi-stage cavitation generating assembly, a forward shearing mechanism of one of the cavitation generating assemblies is connected to a reverse shearing mechanism via a mating conduit; the mating conduit contains an array of multiple Venturi tubes.

[0033] In an optional embodiment, the cavitation generating device further includes a storage tank, an inlet pipe, an outlet pipe, a bypass pipe, a bypass regulating valve, and a pressurizing pump; the storage tank is connected to the inlet of the multi-stage cavitation generating component through the inlet pipe, and the outlet of the multi-stage cavitation generating component is connected to the storage tank through the outlet pipe; the pressurizing pump is mounted on the inlet pipe; the inlet of the bypass pipe is connected to the inlet pipe, the outlet of the bypass pipe is connected to the storage tank, and the bypass regulating valve is mounted on the bypass pipe.

[0034] The beneficial effects of the embodiments of the present invention include, for example:

[0035] This scheme utilizes a high-speed multiphase flow-assisted hydraulic cavitation method to remove new pollutants. Targeting the characteristics of low concentration and high stability of new pollutants in wastewater, pre-treated wastewater is pressurized and pumped into the inlet of a reverse shear mechanism. Within this mechanism, the wastewater containing new pollutants is accelerated and pressurized, forming a high-speed gas-liquid multiphase flow. At the outlet of the reverse shear mechanism and in the connecting pipes, cavitation occurs due to pressure reduction, generating high-energy-density hydroxyl radicals for the removal of low-concentration new pollutants. By arranging Venturi tubes in an array within the intermediate pipes, the Venturi effect is utilized to inject fluid into these pipes. The fluid ejected from the Venturi tubes collides with the main fluid in the intermediate pipes, increasing the mass transfer rate between free radicals and new pollutants in the wastewater. This effectively removes low-concentration new pollutants and increases the solubility of gas in the wastewater, enhancing the cavitation effect of the subsequent forward shear mechanism. Subsequently, the high-speed multiphase flow in the connecting pipes enters the forward shear mechanism, where a large number of uniformly distributed hydroxyl radicals are formed at the diffusion outlet. These radicals are used to remove conventional organic matter from the wastewater, achieving synergistic treatment of multiple pollutants in wastewater containing new pollutants. Attached Figure Description

[0036] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0037] Figure 1 This is a schematic diagram of the cavitation generating device according to an embodiment of the present invention;

[0038] Figure 2 This is a hydroxyl radical distribution diagram of Example 1 of the present invention;

[0039] Figure 3 This is a hydroxyl radical distribution diagram of Example 2 of the present invention;

[0040] Figure 4This is a diagram showing the velocity field, mass transfer rate field, and void fraction distribution of Embodiment 3 of the present invention.

[0041] Figure 5 This is a diagram showing the distribution of the vortex field formed by the wastewater flowing through the surrounding fluid in the intermediate pipe of Embodiment 4 of the present invention.

[0042] Figure 6 This is a diagram showing the velocity and pressure field distributions generated by the collision between the vortex formed by the wastewater flowing through the surrounding fluid and the jet fluid from the Venturi tube in the intermediate pipe of Embodiment 5 of the present invention.

[0043] Figure 7 This is a velocity field distribution diagram of the intermediate pipe in Comparative Example 1 of the present invention when no fluid flow and Venturi tube are installed.

[0044] Icons: 1-Reverse shearing mechanism; 2-Reverse shearing mechanism outlet pressure gauge; 3-Fluorescent fluid; 4-Venturi tube; 5-Intermediate pipeline pressure gauge; 6-Forward shearing mechanism inlet pressure gauge; 7-Forward shearing mechanism; 8-Forward shearing mechanism outlet pressure gauge; 9-Reservoir tank; 10-Pressure pump; 11-Reverse shearing mechanism inlet pressure gauge; 12-Bypass regulating valve. Detailed Implementation

[0045] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0046] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0047] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0048] In the description of this invention, it should be noted that if terms such as "upper," "lower," "inner," or "outer" are used to indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship in which the product of this invention is usually placed, they are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention.

[0049] Furthermore, the terms "first" and "second" are used only to distinguish descriptions and should not be interpreted as indicating or implying relative importance.

[0050] It should be noted that, where there is no conflict, the features in the embodiments of the present invention can be combined with each other.

[0051] Please refer to Figure 1 This embodiment provides a method for removing new pollutants using hydraulic cavitation in high-speed multiphase flow with enhanced mass transfer. The method is based on a cavitation generator, which includes multi-stage cavitation generating components arranged in series. Each stage of the cavitation generating component includes a reverse shearing mechanism 1, a connecting pipe, and a forward shearing mechanism 7 connected in sequence. The connecting pipe is equipped with an array of Venturi tubes 4. The method includes at least the following steps:

[0052] The pretreated wastewater containing new pollutants is pumped to the inlet of the reverse shear mechanism 1. The reverse shear mechanism 1 is used to accelerate and pressurize the wastewater to form a high-speed multiphase flow. Cavitation occurs at the outlet of the reverse shear mechanism 1 to generate a primary fluid with high energy density hydroxyl radicals.

[0053] The initial fluid is transported to a connecting pipe with an array of Venturi tubes 4, where it is fully disturbed and mixed with the fluid jetted from the Venturi tubes to generate a high-speed multiphase mid-section fluid, which is then output from the outlet of the connecting pipe.

[0054] The intermediate fluid is transported to the inlet of the forward shearing mechanism 7, and the forward shearing mechanism 7 further pressurizes the intermediate fluid. Cavitation occurs at the outlet of the forward shearing mechanism 7 to generate a final fluid with a large number of uniformly distributed hydroxyl radicals.

[0055] The concentration of the target pollutant in the final fluid stage is detected. If the concentration of the target pollutant is greater than the preset concentration value, the above steps are repeated or a multi-stage cavitation generation component is added until the concentration of the target pollutant is less than or equal to the preset concentration value.

[0056] It should be noted that in the intermediate pipeline, Venturi tubes 4 arranged in an array around the pipeline inject fluid into the wastewater containing new pollutants using the Venturi effect. The fluid exiting the Venturi tubes 4 collides and mixes with the high-speed wastewater in the connecting pipeline, increasing the degree of wastewater turbulence, improving the mass transfer rate, and increasing the amount of dissolved air, thereby enhancing the cavitation effect and pollutant removal efficiency. This ensures the decontamination effect.

[0057] The forward shearing mechanism 7 further pressurizes the high-speed gas-liquid mixed wastewater and generates a large number of uniformly distributed hydroxyl radicals at the outlet to remove various organic substances. The reverse shearing mechanism 1 and the forward shearing mechanism 7 work together to complete the decontamination operation in a timely and efficient manner.

[0058] from Figure 1 It can also be seen that, in the optional embodiments, the cavitation generating device further includes a liquid storage tank 9, an inlet pipe, an outlet pipe, a bypass pipe, a bypass regulating valve 12, and a pressurizing pump 10; the liquid storage tank 9 is connected to the inlet of the multi-stage cavitation generating component through the inlet pipe, and the outlet of the multi-stage cavitation generating component is connected to the liquid storage tank 9 through the outlet pipe; the pressurizing pump 10 is installed on the inlet pipe; the inlet of the bypass pipe is connected to the inlet pipe, the outlet of the bypass pipe is connected to the liquid storage tank 9, and the bypass regulating valve 12 is installed on the bypass pipe.

[0059] Furthermore, the cavitation generating device also includes a pressure gauge 2 at the outlet of the reverse shearing mechanism, a pressure gauge 5 in the intermediate pipeline, a pressure gauge 6 at the inlet of the forward shearing mechanism, a pressure gauge 8 at the outlet of the forward shearing mechanism, and a pressure gauge 11 at the inlet of the reverse shearing mechanism.

[0060] The outlet pressure gauge 2 of the reverse shearing mechanism is located on the intermediate pipe near the end of the reverse shearing mechanism 1, and the intermediate pipe pressure gauge 5 is located on the intermediate pipe; the inlet pressure gauge 6 of the forward shearing mechanism is located on the intermediate pipe near the end of the forward shearing mechanism 7, the inlet pressure gauge 11 of the reverse shearing mechanism is located on the inlet pipe, and the outlet pressure gauge 8 of the forward shearing mechanism is located on the outlet pipe.

[0061] In an optional embodiment, in a multi-stage cavitation generating assembly, the forward shearing mechanism 7 of one cavitation generating assembly is connected to the reverse shearing mechanism 1 via a mating pipe; multiple venturi tubes 4 are arranged in an array in the mating pipe. It should be noted that, optionally, the mating pipe and the connecting pipe have the same structure, and the arrayed venturi tubes are also the same; this is only used to distinguish the internal pipes of the cavitation generating assembly from the pipes connecting adjacent cavitation generating assemblies.

[0062] In an optional implementation, the hydraulic cavitation effect is evaluated by the following formula:

[0063]

[0064] In the formula, C vP is the dimensionless hydraulic cavitation number, P2 is the fully recovered downstream pressure, and P v v0 is the vapor pressure of the wastewater to be treated, v0 is the velocity at the outlet of the cavitation generating structure (the cavitation generating structure here refers to the forward cavitation mechanism 7 or the reverse cavitation mechanism 1, the same below, and will not be repeated), and ρ is the density of the wastewater to be treated.

[0065] Hydraulic cavitation number C v When the value is less than 1, spatialization will occur, C v The smaller the value, the better the cavitation effect, and the more cavitation bubbles are generated; C v The value ranges from 0.1 to 0.3.

[0066] It should be noted that, in order to ensure the quantity of cavitation generated and the intensity of cavitation collapse, and to avoid blockage caused by supercavitation, C v The value ranges from 0.1 to 0.3. Adjusting the corresponding parameters can ensure the hydraulic cavitation effect, thereby ensuring the decontamination effect.

[0067] Furthermore, v0 is adjusted by the pump flow rate (i.e., the pump flow rate of the booster pump 10, hereinafter the same, and will not be repeated) and the rotational speed and number of stages of the cavitation generating structure (i.e., the number of stages of the shear wheel group in the forward cavitation mechanism 7 and the reverse cavitation mechanism 1, hereinafter the same, and will not be repeated); P2 is adjusted by the inlet pressure of the cavitation generating structure and the diameter of the connecting pipe; P v The dissolved gas content in the wastewater is adjusted by changing the fluid ejected through the venturi tube 4; thereby achieving C v Optimal value.

[0068] In an optional embodiment, the reverse shearing mechanism 1 is a rotary contraction structure. Wastewater flows radially into the reverse shearing mechanism 1 and is ejected axially after rotary contraction to generate high-energy-density hydroxyl radicals.

[0069] In an optional embodiment, the forward shearing mechanism 7 is a rotary diffusion structure. Wastewater flows into the forward shearing mechanism 7 along the axial direction and rotates and diffuses radially around the rotary acceleration port to generate a large number of uniformly distributed hydroxyl radicals.

[0070] In an optional implementation, the total jet flow rate of the plurality of venturi tubes 4 is 5%-10% of the wastewater flow rate in the connecting pipe;

[0071] The jet velocity at the venturi nozzle 4 is 0.6-0.8 times the wastewater velocity in the connecting pipe;

[0072] The angle between the spray direction of the Venturi tube 4 and the wastewater flow direction is 10-60°.

[0073] In an optional embodiment, the fluid injected into the connecting pipe by the venturi tube 4 can be at least one of liquid, gas, or mixture; the type and flow rate of the fluid injected in each venturi tube 4 can be different.

[0074] The liquid sprayed by the Venturi tube 4 includes the circulating effluent and process water treated by this method;

[0075] The gas injected by the Venturi tube 4 includes any oxidizing gas such as air, oxygen, or ozone;

[0076] The mixture injected by the Venturi tube 4 includes any combination of the above-mentioned liquid and gas.

[0077] from Figure 1 It can also be seen that, in the optional implementation, a fluid 3 is arranged upstream of the venturi tube 4 in the inner wall of the connecting pipe; after the wastewater flows through the fluid 3, it forms a vortex, which can enhance the degree of wastewater disturbance and increase the collision effect with the fluid jetted from the venturi tube 4.

[0078] Furthermore, the aforementioned reverse shearing mechanism 1, the surrounding fluid 3, the Venturi tube 4, and the forward shearing mechanism 7 constitute a set of Venturi effect-assisted cavitation generation structural components. To shorten processing time or improve processing efficiency, the number of series-connected stages of the components can be increased. When multiple sets of Venturi effect-assisted cavitation generation structural components are arranged in series, the outlet of the forward shearing mechanism 7 of the previous stage is connected to the inlet of the reverse shearing mechanism 1 of the next stage, and the Venturi tubes 4 are also arranged in an array in the intermediate pipes between the two stages of components.

[0079] Example 1

[0080] Using the method for removing new pollutants through hydraulic cavitation in a high-speed multiphase flow with enhanced mass transfer provided in the specific implementation embodiment, the distribution of hydroxyl radicals at the outlet of the reverse shear mechanism 1 was simulated using ANSYS software. The results are as follows: Figure 2 As shown, the highest volume fraction of hydroxyl radicals at the outlet of the reverse shear mechanism 1 is approximately 8.4%, but the radicals are concentrated and have a higher energy density, making it suitable for removing new pollutants with low concentrations and high stability from wastewater.

[0081] Example 2

[0082] Other conditions were the same as in Example 1. Fluid dynamics simulation of the hydroxyl radical distribution at the outlet of the forward-rotating shear mechanism 7 was performed using ANSYS software. The results are as follows: Figure 3 As shown, the highest volume fraction of hydroxyl radicals at the outlet of the forward shearing mechanism 7 is approximately 27.3%, indicating a large and uniformly distributed amount of hydroxyl radicals, which can be used to remove highly difficult conventional organic pollutants.

[0083] Example 3

[0084] Under the same conditions as in Example 2, the outlet velocity field, mass transfer rate field, and cavitation rate distribution of the forward-rotating shearing mechanism 7 are as follows: Figure 4 As shown, the maximum cavitation rate at the outlet of the forward shear mechanism 7 reaches 81.06%, and the average cavitation rate is 24.81%, which is significantly higher than the cavitation occurrence rate reported in existing studies. Furthermore, there is a region with a strong mass transfer rate at the diffusion outlet, which facilitates the reaction between hydroxyl radicals generated by cavitation and various organic compounds.

[0085] Example 4

[0086] Other conditions are the same as in Example 1. The flow field changes when the high-speed wastewater from the outlet of the reverse shear mechanism 1 flows through the fluid 3 in the intermediate pipe as follows: Figure 5 As shown. Downstream of fluid 3, the high-speed wastewater in the intermediate pipe generates a significant vortex, increasing the degree of fluid disturbance. When the fluid is injected using the Venturi tube 4, the fluid at the outlet of the Venturi tube 4 will collide with the vortex of the main fluid in the intermediate pipe, increasing the mixing effect, improving the mass transfer rate between free radicals and pollutants, and increasing the amount of gas dissolved in the wastewater to be treated, thereby enhancing the cavitation effect of the subsequent forward shearing mechanism 7.

[0087] Example 5

[0088] Other conditions are the same as in Example 4. The fluid injected by the Venturi tube 4 is circulating effluent, the injection volume is 10% of the wastewater flow rate, the flow velocity is 0.8 times the wastewater flow velocity, and the injection direction makes an angle of 30° with the wastewater flow direction. The high-speed wastewater from the outlet of the reversing shear mechanism 1 flows through the intermediate pipe around the fluid 3. When the fluid 3 collides with the fluid injected by the Venturi tube 4, the velocity and pressure cloud diagrams of the mixed fluid in the pipe are as follows. Figure 6 As shown in the velocity contour plot, the vortex formed by the wastewater flowing through the surrounding fluid 3 collides with the fluid injected obliquely into the intermediate pipe by the Venturi tube 4, resulting in mixing downstream. The pressure contour plot shows that the energy dissipates downstream after the collision between the fluid injected by the Venturi tube 4 and the high-speed wastewater, creating a low-pressure zone. This pressure drop contributes to cavitation. Overall, the vortex formed by the wastewater flowing through the surrounding fluid 3 and the collision with the fluid injected by the Venturi tube 4 achieve a good mixing effect.

[0089] Comparative Example 1

[0090] Other conditions are the same as in Example 5, except that the fluid 3 and Venturi tube 4 are not installed in the intermediate pipe, and the flow field distribution of the wastewater to be treated from the outlet of the reverse shearing mechanism 1 to the intermediate pipe is as follows. Figure 7 As shown, the flow velocity of the wastewater to be treated gradually decreases from the outlet of the reverse shear mechanism 1 to the intermediate pipe, and the flow field distribution is continuous without obvious disturbance. Under this condition, the mass transfer rate between free radicals and pollutants in the wastewater is low, and the cavitation effect is poor.

[0091] In summary, the embodiments of the present invention provide a method for removing new pollutants by hydraulic cavitation in high-speed multiphase flow with enhanced mass transfer, which has at least the following advantages:

[0092] (1) The present invention proposes a method for removing new pollutants by hydraulic cavitation in high-speed multiphase flow with enhanced mass transfer. The method utilizes the Venturi effect to spray fluid into the wastewater and collide it with the high-speed wastewater in the intermediate pipe of the outlet of the reverse shearing mechanism 1, thereby enhancing the disturbance of the wastewater, increasing the mass transfer rate, improving the removal effect of new pollutants, and increasing the amount of gas dissolved, so as to improve the cavitation effect of the subsequent forward shearing mechanism 7.

[0093] (2) By utilizing the contraction mode of the reverse shear mechanism 1, high-energy-density hydroxyl radicals are formed to remove new pollutants with strong stability and low concentration. Combined with the diffusion outlet of the forward shear mechanism 7, a large number of uniformly distributed hydroxyl radicals are formed to remove the interference of conventional high-difficulty organic matter, thereby achieving synergistic and efficient treatment of wastewater containing low concentration of new pollutants, and with a large treatment throughput.

[0094] (3) By using the array of Venturi tubes 4, the Venturi effect can be enhanced to increase mass transfer through the jetting and collision of various fluids such as air, oxygen, ozone, circulating treated water, and treated process water into the wastewater in the middle pipe with different combinations, flow rates, and flow velocities. This method is flexible, simple, convenient, and easy to adjust.

[0095] The above are merely specific embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for removing new pollutants by hydraulic cavitation in high-speed multiphase flow with enhanced mass transfer, the method being based on a cavitation generating device comprising multi-stage cavitation generating components arranged in series, each stage of the cavitation generating component comprising a reverse shearing mechanism (1), a connecting pipe, and a forward shearing mechanism (7) connected in sequence, the connecting pipe being provided with an array of Venturi tubes (4); characterized in that, At least the following steps are included: The pretreated wastewater containing new pollutants is pumped to the inlet of the reverse shear mechanism (1). The reverse shear mechanism (1) is used to accelerate and pressurize the wastewater to form a high-speed multiphase flow. Cavitation occurs at the outlet of the reverse shear mechanism (1) to generate a primary fluid with high energy density hydroxyl radicals. The initial fluid is transported to a connecting pipe with an array of Venturi tubes (4), where it is fully disturbed and mixed with the fluid ejected from the Venturi tubes (4) to generate a high-speed multiphase mid-section fluid. The intermediate fluid is transported to the inlet of the forward shearing mechanism (7), and the forward shearing mechanism (7) further pressurizes the intermediate fluid, and cavitation occurs at the outlet of the forward shearing mechanism (7) to generate a final fluid with a large number of uniformly distributed hydroxyl radicals. Detect the concentration of the target pollutant in the final fluid stage; If the target pollutant concentration is greater than the preset concentration value, repeat the above steps or add a multi-stage cavitation generation component until the target pollutant concentration is less than or equal to the preset concentration value. The cavitation generating device further includes a storage tank (9), an inlet pipe, an outlet pipe, a bypass pipe, a bypass regulating valve (12), and a pressurizing pump (10); the storage tank (9) is connected to the inlet of the multi-stage cavitation generating component through the inlet pipe, and the outlet of the multi-stage cavitation generating component is connected to the storage tank (9) through the outlet pipe; the pressurizing pump (10) is installed on the inlet pipe; the inlet of the bypass pipe is connected to the inlet pipe, the outlet of the bypass pipe is connected to the storage tank (9), and the bypass regulating valve (12) is installed on the bypass pipe; The cavitation generator also includes a reverse shear mechanism outlet pressure gauge (2), an intermediate pipeline pressure gauge (5), a forward shear mechanism inlet pressure gauge (6), a forward shear mechanism outlet pressure gauge (8), and a reverse shear mechanism inlet pressure gauge (11). The reverse shear mechanism outlet pressure gauge (2) is located on the intermediate pipeline near the end of the reverse shear mechanism (1), and the intermediate pipeline pressure gauge (5) is located on the intermediate pipeline. The forward shear mechanism inlet pressure gauge (6) is located on the intermediate pipeline near the end of the forward shear mechanism (7), the reverse shear mechanism inlet pressure gauge (11) is located on the inlet pipe, and the forward shear mechanism outlet pressure gauge (8) is located on the outlet pipe.

2. The method for removing new pollutants by hydraulic cavitation in high-speed multiphase flow with assisted enhanced mass transfer, as described in claim 1, is characterized in that... The hydraulic cavitation effect is evaluated by the following formula: In the formula, The dimensionless hydraulic cavitation number. To fully restore downstream pressure, The vapor pressure of the wastewater to be treated. It is the velocity at the exit of the cavitation generation structure. The density of the wastewater to be treated; Hydraulic cavitation number When the value is less than 1, voidification will occur. The smaller the value, the better the cavitation effect, and the more cavitation bubbles are generated; The value ranges from 0.1 to 0.

3.

3. The method for removing new pollutants by hydraulic cavitation in high-speed multiphase flow with assisted enhanced mass transfer according to claim 2, characterized in that: The pump flow rate and the rotational speed and number of stages of the cavitation generator structure are adjusted accordingly. The pressure at the inlet of the cavitation generator structure and the diameter of the connecting pipe are adjusted. The amount of dissolved gas in the wastewater to be treated is adjusted by changing the fluid ejected from the Venturi tube (4); Thus achieve Optimal value.

4. The method for removing new pollutants by hydraulic cavitation in high-speed multiphase flow with assisted enhanced mass transfer according to claim 1, characterized in that: The reverse shearing mechanism (1) is a rotary contraction structure. Wastewater flows in radially into the reverse shearing mechanism (1) and is sprayed out axially after rotary contraction to generate high-energy-density hydroxyl radicals.

5. The method for removing new pollutants by hydraulic cavitation in high-speed multiphase flow with assisted enhanced mass transfer according to claim 1, characterized in that: The forward shearing mechanism (7) is a rotary diffusion structure. Wastewater flows into the forward shearing mechanism (7) along the axial direction and rotates and diffuses radially around the rotary acceleration port to generate a large number of uniformly distributed hydroxyl radicals.

6. The method for removing new pollutants by hydraulic cavitation in high-speed multiphase flow with assisted enhanced mass transfer according to claim 1, characterized in that: The total jet flow rate of the plurality of Venturi tubes (4) is 5%-10% of the wastewater flow rate in the connecting pipe; The jet velocity of the Venturi tube (4) is 0.6-0.8 times the wastewater velocity in the connecting pipe; The angle between the spray direction of the Venturi tube (4) and the flow direction of the wastewater is 10-60°.

7. The method for removing new pollutants by hydraulic cavitation in high-speed multiphase flow with assisted enhanced mass transfer according to claim 6, characterized in that: In the connecting pipe, the fluid injected into the connecting pipe by the Venturi tube (4) can be at least one of liquid, gas or mixture; The liquid sprayed by the Venturi tube (4) includes the circulating effluent and process water treated by this method; The gas ejected by the Venturi tube (4) includes any oxidizing gas such as air, oxygen, or ozone; The mixture injected by the Venturi tube (4) includes any combination of the above-mentioned liquid and gas.

8. The method for removing new pollutants by hydraulic cavitation in high-speed multiphase flow with assisted enhanced mass transfer according to claim 1, characterized in that: In the inner wall of the connecting pipe, a fluid-filled pipe (3) is arranged upstream of the venturi tube (4); After the wastewater flows through the surrounding fluid (3), it forms a vortex, which can enhance the degree of wastewater disturbance and increase the collision effect with the fluid jetted from the Venturi tube (4).

9. The method for removing new pollutants by hydraulic cavitation in high-speed multiphase flow with assisted enhanced mass transfer according to claim 1, characterized in that: In a multi-stage cavitation generating assembly, a forward shearing mechanism (7) of one of the cavitation generating assemblies is connected to a reverse shearing mechanism (1) via an intermediate pipe; a plurality of venturi tubes (4) are arranged in an array in the intermediate pipe.

Images