Axial flow cyclone floating oil-water separation device and method

Abstract

This invention provides an axial-flow cyclone flotation oil-water separation device and method. The separation device includes, from bottom to top, a swirl-initiating section, a first converging section, a stabilizing section, and a separation section. The swirl-initiating section has a swirl-initiating device at its bottom inlet; the first converging section is a frustum-shaped connecting pipe section; the stabilizing section is a long column with an enhanced swirl device at its upper part; and the separation section contains a second converging section with a frustum-shaped structure. The separation method includes the following steps: obtaining an oil-water-gas three-phase mixture; providing appropriate turbulent kinetic energy to the mixture; achieving a uniform transition of the internal flow field; completing the stable adhesion of oil droplets and bubbles; and separating the oil and water phases. This invention redesigns the equipment based on the existing principle of air flotation cyclone coupling. The new process is suitable for the compact treatment of heavy and fine oil droplets in oily wastewater, achieving rapid separation in a short process.

Description

Technical Field

[0001] This invention relates to the field of oil-water separation equipment technology, specifically to an axial flow cyclone flotation oil-water separation device and method. Background Technology

[0002] Driven by the practical needs of environmental governance and the resource utilization of pollutants, the separation of trace oils from oily wastewater has become a research hotspot in the field of water treatment. There is an urgent need for efficient, energy-saving, and compact separation technologies, with hydrocyclones being one of the most effective separation devices. However, hydrocyclones are not ideal for removing heavy oil droplets with densities close to water and fine oil droplets with smaller particle sizes. One existing solution is to add microbubbles to the hydrocyclone. These bubbles adhere to the oil droplets, reducing the density of the oil droplet-bubble adhering mass, and achieving oil-water separation due to the centrifugal force difference caused by the density difference. Therefore, the integrated air flotation-cyclone treatment technology (or air flotation flotation), which combines hydrocyclone and air flotation unit treatment technologies, can effectively enhance the oil removal effect of hydrocyclone treatment.

[0003] When using cyclone flotation technology to remove oil droplets from wastewater, the collision probability and adhesion stability of oil droplets and air bubbles determine the oil removal efficiency. Cyclone flotation is only effective for removing oil droplets from wastewater when air bubbles and oil droplets are stably bound together and unlikely to detach. Numerous studies have shown that appropriate turbulent kinetic energy can increase the collision efficiency between oil droplets and air bubbles and improve the stability of the oil droplet-air bubble adherent. However, current cyclone flotation separators, modified from hydrocyclones, primarily use conical hydrocyclones with tangential inlet inlet. Tangential inlet inlet inlet requires high liquid velocity and kinetic energy, which not only prevents stable adhesion between air bubbles and oil droplets but also causes droplet and bubble breakage, disrupting the flow field and interfering with oil-water separation. Axial-flow hydrocyclones, on the other hand, rely on swirling blades for swirl, resulting in a much lower inlet turbulent kinetic energy compared to conical hydrocyclones. Furthermore, the swirling blades ensure uniform fluid flow and effectively prevent eccentricity. However, the technical principles of oil removal using axial-flow hydrocyclones and axial-flow cyclone flotation separators differ. To allow sufficient time for oil droplets and bubbles to collide and adhere, forming a stable lifting body, the length of an axial-flow cyclone flotation separator must be longer than that of a traditional axial-flow hydrocyclone separator. For example, the axial-flow downhole cyclone oil-water separator designed by Wu Yingxiang of the Institute of Mechanics, Chinese Academy of Sciences, cannot be directly applied to the cyclone flotation field. Firstly, this device is designed to treat large-scale oil-water mixtures (oil content above 1%), and its large inner diameter prevents effective treatment of trace amounts of oil (oil content below 0.1%) in oily wastewater. Secondly, its short length fails to provide sufficient time for microbubbles and oil droplets to collide and adhere. Increasing the inlet flow velocity to overcome the attenuation of cyclone intensity under gravity would repeat the drawbacks of tangential inlet hydrocyclones. Furthermore, CN113636617B discloses a method and apparatus for rapid pre-algae removal in water bodies using weak cyclone-coupled micro-air flotation. However, this method and apparatus rely on gas-solid collision and adhesion, which differs from the thermodynamic and fluid dynamic principles of gas-water collision and adhesion. Consequently, the equipment cannot achieve effective oil-water separation through cyclone flotation. Therefore, existing axial-flow hydrocyclones cannot be directly used for cyclone flotation coupled oil removal. Thus, there is an urgent need for an axial-flow cyclone flotation separation device and method that can combine cyclone and air flotation unit treatment technologies to improve the separation effect of heavy oil droplets and fine oil droplets. Summary of the Invention

[0004] To address the aforementioned problems, this invention provides an axial-flow cyclone flotation oil-water separation device and method. The separation device and method, through the design of a novel axial-flow cyclone flotation separator structure, effectively combines cyclone and flotation unit processing technologies, thereby improving the separation effect of heavy oil and fine oil.

[0005] Therefore, the first objective of this invention is to provide an axial-flow cyclone flotation oil-water separator, the separator comprising, from bottom to top, a swirl initiation section, a first converging section, a swirl stabilization section, and a separation section, wherein:

[0006] The swirl-inducing section is located at the bottom of the separation device. The diameter D1 of the swirl-inducing section is 20-50 mm and the length L1 is 2D1-4D1. It is equipped with a water inlet and a swirl-inducing device. The water inlet is located at the bottom of the swirl-inducing section and the swirl-inducing device is located above the water inlet.

[0007] The first tapering section is a frustum-shaped connecting pipe section that is larger at the bottom and smaller at the top, with a length L2 of 2L1 to 5L1. Its lower end and upper end are connected to the starting section and the stabilizing section, respectively, and the outer diameter of the lower end matches the outer diameter of the starting section, and the outer diameter of the upper end matches the outer diameter of the stabilizing section; the included angle β between the pipe wall of the first tapering section and the pipe wall of the starting section is 174° to 179°.

[0008] The stabilizing section is long and cylindrical, with a diameter D2 of 2 / 3D1 to 5 / 6D1 and a length L3 of 4L1 to 8L1. A swirl enhancement device is provided in the upper middle part of the stabilizing section.

[0009] The separation section is located at the head of the separation device, with a length L4 of 2L1 to 4L1. It has a single vertically distributed oil outlet at its top and two horizontally symmetrically distributed water outlets on both sides of the top. The center of the cavity of the separation section has a second tapering section, which is a frustum-shaped connecting pipe section that is larger at the bottom and smaller at the top. Its lower end and upper end are connected to the stabilizing section and the oil outlet, respectively. The outer diameter of the lower end matches the outer diameter of the stabilizing section, and the outer diameter of the upper end matches the outer diameter of the oil outlet. The included angle δ between the pipe wall of the second tapering section and the pipe wall of the stabilizing section is 172° to 178°.

[0010] According to the present invention, the swirl-starting device disposed inside the swirl-starting section is provided with a core, the bottom and top of the core being configured as a semi-ellipsoidal shape, and a swirl-starting blade being disposed in the middle of the core.

[0011] Furthermore, the swirl blade includes a lower direct current section and an upper swirl section, wherein the direct current section is a vertical plate configuration and the swirl section is a spiral plate configuration.

[0012] Furthermore, the swirl angle α between the DC section and the swirl section is 120° to 140°, and the number of the swirl-initiating blades is set to 4 to 6.

[0013] Furthermore, the spun blade can be fixed to the inner wall of the spun section by welding or other means.

[0014] Furthermore, the outer diameter D7 of the blades of the swirl-starting device is the same as that of D1, the radial width D8 of the core of the swirl-starting device is 1 / 4D7 to 1 / 2D7, the length H1 of the swirl-starting blade is 1.25D7 to 3D7, and the length H2 of the swirl-starting device is 1.5D7 to 3.5D7.

[0015] According to the present invention, the enhanced swirl device disposed inside the stabilizing section is provided with a core, the top of the core is configured as a hemispherical shape, the bottom is configured as a semi-ellipsoidal shape, and the middle part of the core is provided with enhanced swirl blades.

[0016] Furthermore, the enhanced swirl blade has a spiral blade configuration, and the interior of the core is configured with a through-hole structure, the diameter D11 of which is 1 / 4D10 to 1 / 2D10.

[0017] Furthermore, the reinforced swirl blades can be fixed to the inner wall of the stabilizing section by welding or other means.

[0018] Furthermore, the angle γ between the enhanced swirl blade and the vertical line is 120° to 140°, and the number of enhanced swirl blades is set to 4 to 6.

[0019] Furthermore, the outer diameter D9 of the blades of the enhanced swirl device is equal to that of D2, the radial width D10 of the core of the enhanced swirl device is 1 / 2D9 to 3 / 4D9, the length H3 of the enhanced swirl blade is 1.25D9 to 3D9, the length H4 of the enhanced swirl device is 1.5D9 to 3.5D9, and the installation height Z of the enhanced swirl blade is 1 / 2L3 to 3 / 4L3.

[0020] According to the present invention, a plurality of circular outlets are evenly distributed on the second tapering section inside the separation section, and the separation section is divided into an inner cavity and an outer cavity by the second tapering section, wherein the diameter D6 of the outer cavity is 1.2D2 to 2D2.

[0021] Furthermore, the diameter D3 of the oil outlet is 1 / 4D2 to 1 / 2D2, the diameter D4 of the water outlet is 1D3 to 2D3, and the diameter D5 of the water outlet hole is 1 / 4D4 to 1 / 2D4.

[0022] The second objective of this invention is to provide an axial-flow cyclone flotation oil-water separation method to solve the problem that existing hydrocyclones cannot effectively separate heavy oil and fine oil, thereby improving oil removal efficiency. The separation method includes the following steps:

[0023] Step 1: Obtain the three-phase mixture of oil, water, and gas.

[0024] First, pressurized dissolved air water is introduced into the gas release plate in the water inlet pool below the separation device. The high-pressure gas in the pressurized dissolved air water is released through the gas release plate, forming microbubbles. Then, oily wastewater is introduced into the water inlet pool to obtain the oil-water-gas three-phase mixture.

[0025] Step 2: Provide appropriate turbulent kinetic energy to the mixture:

[0026] The mixture then enters the swirl-starting section through the inlet located at the bottom of the separator. Inside the swirl-starting section, the blades of the swirl-starting device generate tangential velocity under the swirling action. The appropriate turbulent kinetic energy generated in this process helps the oil droplets and bubbles to collide and adhere, forming a unified lifting body, and completing the initial separation of oil, gas and water phases under the centrifugal force difference caused by the density difference.

[0027] Step 3: Achieve a uniform transition in the internal flow field:

[0028] The mixture then passes through a first converging section with a frustum-shaped structure, which can gently increase the tangential velocity of the mixture, reduce the influence of the decrease in centrifugal force as the mixture moves upward, and make the internal flow field of the device smoothly transition to the swirl stabilizer section.

[0029] Step 4: Achieve stable adhesion of oil droplets and bubbles:

[0030] The mixture then passes through a stabilizing section with a flat section structure, which provides sufficient space for oil-water separation. Oil droplets in the wastewater spread and adhere on the microbubbles, and the tangential velocity of the mixture is further increased by the swirling action of the blades of the enhanced swirling device inside the stabilizing section, thus completing the further separation of oil, gas and water phases under the centrifugal force difference caused by the density difference.

[0031] Step 5: Separation of the oil phase and the aqueous phase:

[0032] The mixture then passes through a separation section located at the head of the cylinder. The frustum-shaped structure of the second tapering section inside the separation section further enhances the centrifugal force difference between the aqueous phase and the oil phase. Under the action of centrifugal force, the aqueous phase is discharged from the water outlets evenly distributed on the second tapering section and enters the aqueous phase space, thus achieving the separation of the aqueous phase and the oil phase. Subsequently, the aqueous phase is discharged from the water outlets on both sides, while the oil and gas are discharged from the oil outlet at the top.

[0033] According to the present invention, the oil particles in the oily wastewater in step one have a diameter of 10 μm or larger and a density of 0.6–0.95 g / cm³. 3 .

[0034] According to the present invention, the microbubble particle size in step one is 5 to 30 μm.

[0035] The present invention has the following beneficial effects:

[0036] 1. The axial flow cyclone flotation oil-water separation device of the present invention couples the cyclone and flotation processes into one, which has high removal efficiency for heavy oil droplets and fine oil droplets, and can realize efficient pretreatment of oily wastewater;

[0037] 2. The swirl initiation device can reduce the requirement for inlet flow velocity and form a gentle swirling flow field, which can avoid the breakup of oil droplets and bubbles and the instability of oil droplet-bubble adhesion caused by excessive turbulent kinetic energy; and the swirl blades can make the fluid flow uniformly and effectively prevent flow field eccentricity.

[0038] 3. The design of the first tapering section can reduce the attenuation of the swirling intensity under the action of gravity. Firstly, it can increase the collision efficiency of oil droplets and bubbles, making the upward flow of the light phase components in the swirling field more stable, and allowing the internal flow field of the device to smoothly transition to the swirl steady section. The swirl steady section provides sufficient space and time for the stable adhesion of oil droplets and bubbles to form a unified lifting body.

[0039] 4. By enhancing the re-swirl generation of the cyclone device, the problem of the attenuation of the swirl intensity in the flow field of the axial flow cyclone flotation separator under the action of gravity can be effectively solved, further increasing the centripetal collision velocity of bubbles, oil droplets, and bubble-oil droplet adhering bodies. The flotation performance of the cyclone flotation is effectively improved, and the oil removal efficiency is further enhanced. At the same time, the hollow design of the enhanced cyclone device can avoid the disturbance effect on the flow field after the air core is damaged.

[0040] 5. Meanwhile, the axial flow cyclone flotation oil-water separator of the present invention has a compact structure, occupies a small area, has no moving parts inside, operates stably, and can be applied to liquid-liquid separation processes in different fields. Attached Figure Description

[0041] Figure 1 This is a schematic diagram of the axial flow cyclone flotation oil-water separation device of the present invention.

[0042] Figure 2 This is a structural cross-sectional view of the axial flow cyclone flotation oil-water separation device of the present invention.

[0043] Figure 3 This is a schematic diagram of the swirl-starting device of the separation apparatus of the present invention.

[0044] Figure 4 This is a structural dimension diagram of the swirl-starting device of the separation apparatus of the present invention.

[0045] Figure 5 This is a schematic diagram of the enhanced cyclone device of the separation apparatus of the present invention.

[0046] Figure 6 This is a structural dimension diagram of the enhanced cyclone device of the separation apparatus of the present invention.

[0047] Figure 7 This is a cross-sectional view of the head section of the separation device of the present invention.

[0048] Figure 8 This is a top view of the head portion of the separation device of the present invention.

[0049] Figure 9 This is a schematic flowchart of the separation method of the present invention.

[0050] Figure 10 This is a schematic diagram of step one of the separation method of the present invention.

[0051] Drawing number explanation:

[0052] 1-Swirl initiation section; 11-First flange; 12-Water inlet; 13-Swirl initiation device; 131-Core column; 132-Swirl initiation blade; 2-First tapering section; 3-Swirl stabilization section; 31-Enhanced swirling device; 311-Core column; 312-Enhanced swirling blade; 313-Through hole structure; 4-Separation section; 41-Second flange; 42-Oil outlet; 43-Water outlet; 44-Second tapering section; 45-Water outlet hole; 5-Water inlet pool; 51-Gas release plate; 52-Microbubble. Detailed Implementation

[0053] The present invention will be further described in detail below with reference to embodiments. It should be understood that the following embodiments are only used to further illustrate the present invention and should not be construed as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the content of the present invention still fall within the scope of protection of the present invention.

[0054] Example 1: Axial Flow Cyclone Oil-Water Separator

[0055] like Figure 1 and Figure 2 As shown, the axial flow cyclone flotation oil-water separator of the present invention includes, from bottom to top, a swirl-initiating section 1, a first tapering section 2, a swirl-stabilizing section 3, and a separation section 4. A first flange 11 and a second flange 41 are respectively provided below the swirl-initiating section 1 and the separation section 4 for secure installation of the separation device. Wherein:

[0056] The swirl-starting section 1 is located at the bottom of the separation device. It is equipped with an inlet 12 and a swirl-starting device 13. The inlet 12 is located at the bottom of the swirl-starting section 1, and the swirl-starting device 13 is located above the inlet 12. It is used to make the oil-gas-water mixture entering the swirl-starting section 1 swirl. The appropriate turbulent kinetic energy generated in this process helps oil droplets and bubbles to collide and adhere. Under the centrifugal force difference caused by the density difference, the initial separation of oil, gas and water phases is completed.

[0057] The first tapering section 2 is a frustum-shaped connecting pipe section that is larger at the bottom and smaller at the top. Its lower end and upper end are connected to the swirl-initiating section 1 and the swirl-stabilizing section 3, respectively. The outer diameter of the lower end matches the outer diameter of the swirl-initiating section 1, and the outer diameter of the upper end matches the outer diameter of the swirl-stabilizing section 3. This structure helps to increase the tangential velocity of the liquid and reduces the impact of the decrease in centrifugal force as the mixture moves upward.

[0058] The stabilizing section 3 is a long column shape, which provides sufficient space for oil droplets and bubbles to collide and adhere, and to separate from the water phase again under the centrifugal force difference caused by the density difference; the middle and upper part of the stabilizing section 3 is provided with a strengthening swirling device 31, which is used to further increase the tangential velocity of the mixture and reduce the impact of the decrease in centrifugal force.

[0059] The separation section 4 is located at the head of the separation device. It has a single vertically distributed oil outlet 42 at its top and two horizontally symmetrically distributed water outlets 43 on either side of the top, used for discharging the separated oil, gas, and water phases, respectively. A second tapering section 44 is located at the center of the cavity of the separation section 4. This second tapering section 44 is a frustum-shaped connecting pipe section, wider at the bottom and narrower at the top. Its lower and upper ends connect to the stabilizing section 3 and the oil outlet 42, respectively. The outer diameter of the lower end matches the outer diameter of the stabilizing section 3, and the outer diameter of the upper end matches the outer diameter of the oil outlet 42.

[0060] Furthermore, such as Figure 3 and Figure 4 As shown, the swirl-inducing device 13 disposed inside the swirl-inducing section 1 is provided with a core 131. The bottom and top of the core 131 are configured as a semi-ellipsoid to reduce flow resistance, thereby achieving a smooth transition of the fluid. A swirl-inducing blade 132 is disposed in the middle of the core 131. The swirl-inducing blade 132 includes a lower direct flow section and an upper swirling flow section. The direct flow section is a vertical plate configuration, and the swirling flow section is a spiral plate configuration. The swirl-inducing blade 132 can be fixed to the inner wall of the swirl-inducing section by welding or other means. The number of swirl-inducing blades 132 is set to 4 to 6.

[0061] Furthermore, such as Figure 5 and Figure 6As shown, the enhanced swirling device 31, located inside the stabilizing section 3, has a core 311. The top of the core 311 is hemispherical, and the bottom is semi-ellipsoidal. Since the swirling kinetic energy of the mixture decreases significantly after traveling a certain height, the enhanced swirling device 31 can further increase the tangential velocity of the mixture. The core 311 has enhanced swirling blades 312 in its middle section. These blades are helical and fixed to the inner wall of the stabilizing section 3 by welding or other methods. The core 311 has a through-hole structure 313. This is because gas has the lowest density, and a gas core will be generated in the central section after the cyclone separator operates normally. To prevent disturbance of the gas core from affecting the stability of the swirling field, the core 311 has a through-hole. The number of enhanced swirling blades 312 is set to 4 to 6.

[0062] Furthermore, such as Figure 7 and Figure 8 As shown, several circular water outlets 45 are evenly distributed on the second tapering section 44 inside the separation section 4. The second tapering section 44 divides the separation section 4 into an inner cavity and an outer cavity. The inner cavity is a mixed phase space and is connected to the oil outlet section, while the outer cavity is a water phase space and is connected to the water outlet section. In the separation section, the structure of the second tapering section 44 further enhances the centrifugal force difference between the water phase and the oil phase. Under the action of centrifugal force, the water phase is discharged from the water outlet 45, enters the water phase space, and is discharged from the water outlet 43, while the oil and gas are discharged from the oil outlet 42.

[0063] like Figures 1 to 8 As shown, the specific structural dimensions of the separation device of the present invention are as follows.

[0064] 1. The diameter dimensions of the specific structure of the separation device of the present invention are as follows:

[0065] The diameter of the starting section 1 is D1, which is 20-50 mm.

[0066] The diameter D2 of the stabilizing section 3 is 2 / 3D1 to 5 / 6D1;

[0067] The diameter D3 of the oil outlet pipe is 1 / 4D2 to 1 / 2D2; the diameter D4 of the water outlet pipe is 1D3 to 2D3; and the diameter D5 of the water outlet hole is 1 / 4D4 to 1 / 2D4.

[0068] The diameter D6 of the aqueous phase space is 1.2D2 to 2D2;

[0069] The outer diameter D7 of the blade 132 of the swirl-starting device is the same as that of D1, and the radial width D8 of the core 131 of the swirl-starting device is 1 / 4D7 to 1 / 2D7.

[0070] The outer diameters D9 and D2 of the blades 312 of the enhanced vortex device are equal, the radial width D10 of the core 311 of the enhanced vortex device is 1 / 2D9 to 3 / 4D9, and the diameter D11 of the internal through-hole structure 313 is 1 / 4D10 to 1 / 2D10.

[0071] 2. The specific length or height dimensions of the separation device of the present invention are as follows:

[0072] The length of the starting section 1 is L1, which is 2D1 to 4D1;

[0073] The length L2 of the first tapered segment 2 is 2L1 to 5L1;

[0074] The length L3 of the stabilizing section 3 is 4L1 to 8L1;

[0075] The length L4 of the separation segment 4 is 2L1 to 4L1;

[0076] The length H1 of the spinning blade 132 is 1.25D7 to 3D7, and the length H2 of the spinning device 13 is 1.5D7 to 3.5D7.

[0077] The length H3 of the enhanced swirl blade 312 is 1.25D9 to 3D9, and the length H4 of the enhanced swirl device 31 is 1.5D9 to 3.5D9; the installation height Z of the enhanced swirl blade 312 is 1 / 2L3 to 3 / 4L3.

[0078] 3. The specific angular dimensions of the separation device of the present invention are as follows:

[0079] The swirl angle α between the DC section and the swirl section of the swirl initiation device 13 is 120° to 140°.

[0080] The included angle β between the tube wall of the starting section 1 and the tube wall of the first tapering section 2 is 174° to 179°.

[0081] The angle γ between the enhanced swirl blade 312 and the vertical line is 120° to 140°.

[0082] The angle δ between the wall of the stabilizing section 3 and the wall of the second tapering section 42 is 172° to 178°.

[0083] The working principle of the separation device of the present invention is as follows:

[0084] First, before the oil-water mixture enters the separation device of this invention through the inlet 12, pressurized dissolved air water is introduced into the gas release plate in the inlet pool below the separation device. The high-pressure gas in the pressurized dissolved air water is released through the gas release plate, forming microbubbles. After the mixture enters the swirl-starting section 1 of the separation device, it first generates tangential velocity under the action of the swirl-starting device 13. During this process, appropriate turbulent kinetic energy helps oil droplets and bubbles collide and adhere, forming a unified lifting body, and completing the initial separation under the centrifugal force difference caused by the density difference. Afterwards, the mixture passes through the first... The first tapering section 2 and the stabilizing section 3 have a frustum-shaped structure that helps increase the tangential velocity of the mixture and reduce the impact of centrifugal force reduction. The straight section structure of the stabilizing section 3 provides sufficient space for oil-water separation. After running for a certain distance, the swirling kinetic energy of the mixture decreases significantly. The enhanced swirling device 31 inside the stabilizing section 3 can further increase the tangential velocity. Finally, in the separation section at the cylinder head, the purified liquid exits from the water outlet 45 and enters the water phase space under the action of centrifugal force, and is discharged from the water outlet 44. The oil and gas are discharged from the oil outlet 43.

[0085] Example 2: Axial Flow Cyclone Flotation Oil-Water Separation Method

[0086] Based on the axial-flow cyclone flotation oil-water separation device of Example 1, this example provides an axial-flow cyclone flotation oil-water separation method. This separation method can be used to separate oil droplets with a particle size greater than 10 μm, or oil with a density of 0.6–0.95 g / cm³. 3 Oily wastewater, wherein the oil droplet size is 10–20 μm or the density of heavy oil is 0.86–0.95 g / cm³. 3 The effective separation of oily wastewater is a significant manifestation of the technological advancement of this invention. For example... Figure 9 As shown, the separation method includes the following steps.

[0087] Step 1: Obtain the three-phase mixture of oil, water, and gas.

[0088] like Figure 10 As shown, a gas release plate 51 is provided in the water inlet pool 5 below the separation device. First, pressurized dissolved gas water is introduced into the gas release plate 51. The high-pressure gas in the pressurized dissolved gas water is released through the gas release plate 51 to form microbubbles 52, wherein the particle size of the microbubbles is 5-30μm. Then, oily wastewater is introduced into the water inlet pool to obtain the oil-water-gas three-phase mixture.

[0089] Step 2: Provide appropriate turbulent kinetic energy to the mixture.

[0090] The mixture then enters the swirl section 1 through the inlet 12 located at the bottom of the separator. The blades of the swirl device 13 inside the swirl section generate tangential velocity under the swirling action. The appropriate turbulent kinetic energy generated in this process helps the oil droplets and bubbles to collide and adhere, forming a unified lifting body, and completing the initial separation of oil, gas and water phases under the centrifugal force difference caused by the density difference.

[0091] Step 3: Achieve a uniform transition in the internal flow field

[0092] The mixture then passes through a first tapering section 2 with a frustum-shaped structure, which can gently increase the tangential velocity of the mixture, reduce the impact of the decrease in centrifugal force as the mixture moves upward, and allow the internal flow field of the device to smoothly transition to the swirl-stabilizing section.

[0093] Step 4: Achieve stable adhesion of oil droplets and bubbles.

[0094] The mixture then passes through a stabilizing section 3 with a straight section structure, which provides sufficient space for oil-water separation. Oil droplets in the wastewater spread and adhere on the microbubbles 52, and the tangential velocity of the mixture is further increased by the swirling action of the blades of the enhanced swirling device 31 inside the stabilizing section 3, thus completing the further separation of oil, gas and water phases under the centrifugal force difference caused by the density difference.

[0095] Step 5: Separation of the oil phase and the aqueous phase

[0096] The mixture then passes through the separation section 4 located at the head of the cylinder. The frustum-shaped structure of the second tapering section 44 inside the separation section 4 further enhances the centrifugal force difference between the aqueous phase and the oil phase. Under the action of centrifugal force, the aqueous phase is discharged from the water outlets 45 evenly distributed on the second tapering section and enters the aqueous phase space, thus realizing the separation of the aqueous phase and the oil phase. Subsequently, the aqueous phase is discharged from the water outlets 43 on both sides, while the oil and gas are discharged from the oil outlet 42 at the top.

[0097] Example 3: Separation effect of the separation device and method of the present invention on oil-water mixtures

[0098] This embodiment focuses on the separation of oil-water mixtures to verify the separation effectiveness of the present invention's separation device and method. The experimental variables are the density of the oil and whether microbubbles are introduced into the cyclone flotation device.

[0099] 1. Structure of the oil-water separator

[0100] The oil-water separation device described in Example 1 has the following specific dimensions: the diameter D1 of the bottom inlet 12 of the swirl-initiating section 1 is 25mm, and the length L1 is 50mm; the vertical length L2 of the first tapering section 2 is 150mm; the diameter D2 of the stabilizing section 3 is 20mm, and the length L3 is 250mm; the length L4 of the separation section 4 is 100mm, the diameter D3 of the oil outlet 42 is 6mm, and the diameter D4 of the water outlet 43 is 8mm; the inner diameter D8 of the swirl-initiating device 13 is 10mm, the height H1 of the swirl blades 132 is 35mm, the number of blades is 6, and the length H2 of the core is 50mm; the inner diameter D10 of the enhanced swirl device 31 is 10mm, the diameter D11 of the through hole 313 is 4mm, the height H3 of the swirl blades is 25mm, the number of blades is 5, and the length H4 of the core is 35mm.

[0101] 2. Prepare oils of different densities.

[0102] Prepare oils of different densities: white oil, vegetable oil, and silicone oil, with densities of 0.85 g / cm³ respectively. 3 0.91g / cm 3 and 0.95g / cm 3 .

[0103] 3. Preparation of oil-water mixture

[0104] The above-mentioned oils were mixed with tap water in different proportions to make the oil content in the mixture approximately 1000 mg / L; the mixture was then placed in a shear emulsifier for appropriate emulsification and stored separately in water tanks to obtain the oil-water mixture.

[0105] 4. Conduct oil-water separation experiments.

[0106] 1) Oil-water separation experiment without air flotation: The oil-water mixture is pumped into an axial flow cyclone flotation separator, with the flow velocity at the inlet fixed at 1 m / s. After the device stabilizes, samples are taken sequentially at the inlet and outlet to measure the oil content in the water.

[0107] 2) Add an oil-water separation experiment using air flotation: Next, start the dissolved air pump. The circulating air-containing water flow rate of the dissolved air pump is 3% of the influent flow rate of the oily wastewater. Adjust the pump to maintain a fixed flow velocity of the oil-air-water mixture at the inlet at 1 m / s. After the device stabilizes, take samples sequentially at the inlet and outlet of the device to measure the oil content in the water.

[0108] 3) Following the steps and methods described above, separate experiments were conducted on oil-water mixtures with different oil densities. The specific results are shown in Table 1.

[0109] 4) When the oil density is 0.91 g / cm³ 3During the experiment, samples were taken at the inlet and outlet of the device, and the particle size distribution of oil droplets in the water was measured. The specific results are shown in Table 2.

[0110] Table 1. Oil-water separation efficiency of mixed oils with and without air flotation for different oil densities.

[0111]

[0112] Table 20.91 g / cm 3 Oil density of mixed oil droplet size distribution with and without air flotation

[0113]

[0114] The results in Table 1 show that using the separation device of the present invention without adding air flotation, the oil density is 0.85 g / cm³. 3 0.91g / cm 3 and 0.95g / cm 3 The separation efficiencies of the oil-water mixture were 75%, 69%, and 59%, respectively. After adding air flotation, the corresponding separation efficiencies were 82%, 79%, and 66%, respectively, all of which were greater than the separation efficiencies without air flotation. This shows that the axial flow separator without air flotation is not very effective in separating heavy oil, while adding air flotation significantly improves the separation efficiency of heavy oil-water mixtures. This indicates that the separation device and method of the present invention can effectively improve the separation effect of traditional axial flow separators on heavy oil-water mixtures.

[0115] As shown in Table 2, for oil droplets with a particle size of less than 10 μm, the addition of air flotation has a limited effect on improving the separation efficiency of droplets of this size. After adding air flotation, the removal efficiency for oil droplets with a size of 10-30 μm is significantly improved, with an improvement exceeding 10%, and the removal efficiency for oil droplets with a size of more than 30 μm is also significantly improved. Therefore, the separation device and method of this invention successfully combine air flotation and axial flow unit treatment technologies, and greatly improves the separation effect of oil-water mixtures. Thus, the new process is suitable for the compact treatment of heavy and fine oil droplets in oily wastewater, achieving rapid separation in a short process flow.

[0116] In summary, the axial-flow cyclone flotation oil-water separation device and method of the present invention, through the design of a novel separator structure, couples cyclone and flotation processes into one, which not only improves the collision probability and adhesion stability of oil droplets and bubbles during the separation process, but also increases the tangential velocity of the liquid during operation. This reduces the impact of the decrease in centrifugal force as the mixed liquid rises, ultimately achieving effective separation of oil, gas, and water phases under the centrifugal force difference caused by density difference. Therefore, the oil-water separation device and method of the present invention can achieve efficient pretreatment of oily wastewater, improve the removal efficiency of heavy oil droplets and fine oil droplets, and greatly improve the separation efficiency of heavy oil and water and the wastewater treatment effect. In addition, the axial-flow cyclone flotation oil-water separation device of the present invention has a compact structure, small footprint, no moving parts, and stable operation, and can be applied to liquid-liquid separation processes in different fields. Therefore, the oil-water separation device and method of the present invention have high practical application value in oil-water separation and wastewater treatment.

[0117] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. An axial-flow cyclone flotation oil-water separation device, characterized in that, It includes, from bottom to top, a starting section, a first contraction section, a stabilizing section, and a separation section, wherein: The oil-water separator is connected to an inlet pool below it, and a gas release plate is installed in the inlet pool to obtain a three-phase mixture of oil, water and gas. The swirl-inducing section is located at the bottom of the separation device and is used to provide appropriate turbulent kinetic energy to the mixture. The diameter D1 of the swirl-inducing section is 20-50 mm and the length L1 is 2 D1-4 D1. It is equipped with an inlet and a swirl-inducing device inside. The inlet is located at the bottom of the swirl-inducing section and the swirl-inducing device is located above the inlet. The first tapering section is a frustum-shaped connecting pipe section that is larger at the bottom and smaller at the top, used to achieve a uniform transition of the internal flow field. Its length L2 is 2 L1 to 5 L1. Its lower end and upper end are connected to the swirl initiation section and the swirl stabilization section, respectively. The outer diameter of the lower end matches the outer diameter of the swirl initiation section, and the outer diameter of the upper end matches the outer diameter of the swirl stabilization section. The included angle β between the pipe wall of the first tapering section and the pipe wall of the swirl initiation section is 174° to 179°. The stabilizing section is long and cylindrical, used to stabilize the adhesion of oil droplets and bubbles. The diameter D2 of the stabilizing section is 2 / 3D1 to 5 / 6D1, and the length L3 is 4L1 to 8L1. A swirling enhancement device is provided in the upper middle part of the stabilizing section. The swirling enhancement device is provided with a core, and a swirling enhancement blade is provided in the middle of the core. The blade has a through-hole structure inside. The separation section is located at the head of the separation device and is used for separating the oil phase and the water phase. Its length L4 is 2 L1 to 4 L1. It has a single vertically distributed oil outlet at its top and two horizontally symmetrically distributed water outlets on both sides of the top. The center of the cavity of the separation section has a second tapering section. The second tapering section is a frustum-shaped connecting pipe section that is larger at the bottom and smaller at the top. Its lower end and upper end are connected to the stabilizing section and the oil outlet, respectively. The outer diameter of the lower end matches the outer diameter of the stabilizing section, and the outer diameter of the upper end matches the outer diameter of the oil outlet. The included angle δ between the pipe wall of the second tapering section and the pipe wall of the stabilizing section is 172° to 178°. The bottom and top of the core are configured as a semi-ellipsoid, and a swirl-inducing blade is provided in the middle of the core. The swirl-inducing blade includes a lower direct-flow section and an upper swirling section. The direct-flow section is a vertical plate configuration, and the swirling section is a spiral plate configuration. The swirl angle α between the direct-flow section and the swirling section is 120° to 140°, and the number of swirl-inducing blades is set to 4 to 6. The outer diameter D7 of the blades of the swirl-inducing device is equal to D1. The radial width D8 of the core of the swirl-inducing device is 1 / 4 D7 to 1 / 2 D7. The length H1 of the swirl-inducing blade is 1.25 D7 to 3 D7, and the length H2 of the swirl-inducing device is 1.5 D7 to 3.5 D7.

2. The oil-water separation device according to claim 1, characterized in that, The top of the core of the enhanced vortex device is configured as a hemispherical shape, and the bottom is configured as a semi-ellipsoidal shape.

3. The oil-water separation device according to claim 1, characterized in that, The angle γ between the enhanced swirl blade and the vertical line is 120-140°, and the number of enhanced swirl blades is set to 4-6.

4. The oil-water separation device according to claim 1, characterized in that, The outer diameters D9 and D2 of the blades of the enhanced swirl device are equal, the radial width D10 of the core of the enhanced swirl device is 1 / 2 D9 to 3 / 4 D9; the length H3 of the enhanced swirl blade is 1.25 D9 to 3 D9, the length H4 of the enhanced swirl device is 1.5 D9 to 3.5 D9, and the installation height Z of the enhanced swirl blade is 1 / 2 L3 to 3 / 4 L3.

5. The oil-water separation device according to claim 4, characterized in that, The reinforced swirl blades have a helical blade configuration, and the diameter D11 of the through hole structure of the core is 1 / 4 D10 to 1 / 2 D10.

6. The oil-water separation device according to claim 1, characterized in that, The second tapering section inside the separation section has several circular water outlet holes evenly distributed on it. The second tapering section divides the separation section into an inner cavity and an outer cavity. The diameter D6 of the outer cavity is 1.2 D2 to 2 D2.

7. The oil-water separation device according to claim 6, characterized in that, The diameter D3 of the oil outlet is The diameter of the water outlet is 1 / 4 D2 to 1 / 2 D2, the diameter of the water outlet is 1 D3 to 2 D3, and the diameter of the water outlet hole is 1 / 4 D4 to 1 / 2 D4.

8. The separation method of the axial flow cyclone flotation oil-water separator according to any one of claims 1-7, characterized in that, The separation method includes the following steps: Step 1: Obtain the three-phase mixture of oil, water, and gas. First, pressurized dissolved air water is introduced into the gas release plate in the water inlet pool below the separation device. The high-pressure gas in the pressurized dissolved air water is released through the gas release plate, forming microbubbles. Then, oily wastewater is introduced into the water inlet pool to obtain the oil-water-gas three-phase mixture. Step 2: Provide appropriate turbulent kinetic energy to the mixture: The mixture then enters the swirl-starting section through the inlet located at the bottom of the separator. Inside the swirl-starting section, the blades of the swirl-starting device generate tangential velocity under the swirling action. The appropriate turbulent kinetic energy generated in this process helps the oil droplets and bubbles to collide and adhere, forming a unified lifting body, and completing the initial separation of oil, gas and water phases under the centrifugal force difference caused by the density difference. Step 3: Achieve a uniform transition of the internal flow field: The mixture then passes through a first converging section with a frustum-shaped structure, which can gently increase the tangential velocity of the mixture, reduce the influence of the decrease in centrifugal force as the mixture moves upward, and make the internal flow field of the device smoothly transition to the swirl stabilizer section. Step 4: Achieve stable adhesion of oil droplets and bubbles: The mixture then passes through a stabilizing section with a flat section structure, which provides sufficient space for oil-water separation. Oil droplets in the wastewater spread and adhere on the microbubbles, and the tangential velocity of the mixture is further increased by the swirling action of the blades of the enhanced swirling device inside the stabilizing section, thus completing the further separation of oil, gas and water phases under the centrifugal force difference caused by the density difference. Step 5: Separation of the oil phase and the aqueous phase: The mixture then passes through a separation section located at the head of the cylinder. The frustum-shaped structure of the second tapering section inside the separation section further enhances the centrifugal force difference between the aqueous phase and the oil phase. Under the action of centrifugal force, the aqueous phase is discharged from the water outlets evenly distributed on the second tapering section and enters the aqueous phase space, thus achieving the separation of the aqueous phase and the oil phase. Subsequently, the aqueous phase is discharged from the water outlets on both sides, while the oil and gas are discharged from the oil outlet at the top.

9. The separation method according to claim 8, characterized in that, The oil particles in the oily wastewater in step one have a diameter greater than 10 μm and a density of 0.6–0.95 g / cm³. 3 .

10. The separation method according to claim 8, characterized in that, The microbubble size in step one is 5–30 μm.

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