A Karman vortex street driven integrated oil coalescence-separation-fouling prevention device and its design method for oily wastewater

Abstract

The present invention provides a Karman vortex street driven oil-containing wastewater oil coalescence-separation-anti-fouling integrated equipment and design method, including a feed end, a vortex street coalescence end, an inertial discrimination end, a vortex street reflux end and a negative / positive pressure inertial separation end; the vortex street coalescence end is used to stimulate the oil-containing wastewater flowing in the flow channel to produce a Karman vortex street effect, and in the absence of chemical agents, the oil droplets in the oil-containing wastewater are subjected to coalescence treatment, and the irregularly dispersed oil droplets in the oil-containing wastewater are coalesced into regular large oil droplets to obtain coalescence-treated oil-containing wastewater, and the coalescence-treated oil-containing wastewater is transported to the inertial discrimination end. The present invention can realize the efficient conversion of micro-oil droplets to large oil droplets, and the precise recovery of large oil droplets. The preparation method of the present invention is simple in process, does not require the addition of agents, is safe and environmentally friendly, can adapt to a variety of oil-containing wastewater treatment scenarios, and fundamentally improves the oil-water separation efficiency.

Description

Technical Field

[0001] The invention belongs to the technical field of drug-free treatment of oily wastewater, and specifically relates to a Karman vortex street driven oil-containing wastewater oil coalescence-separation-anti-fouling integrated equipment and a design method. Background Art

[0002] With the continuous development of industrialization and the acceleration of urbanization, wastewater treatment has become an important issue in the field of environmental protection. Among them, the treatment of oily wastewater is a challenging task. If it is not properly treated, it will not only affect the safety of water quality, but also cause damage to the ecosystem, cause biological toxicity problems, affect human health and bring economic losses.

[0003] Traditional methods for treating oily wastewater usually require the addition of chemical agents, such as polymers, coagulants, etc., to achieve oil-water separation or oil removal. However, the use of chemical agents will not only increase the cost of treatment, but may also cause secondary pollution to the environment. Therefore, there is an urgent need to develop treatment methods without the addition of chemicals. At present, the difficulties of chemical-free treatment are: 1. Low efficient oil-water separation: The realization of chemical-free oil-water treatment faces the problem of efficient oil-water separation. Due to the influence of factors such as small oil-water interfacial tension, small difference in oil-water density, irregular oil droplet size, and close specific gravity of oil and water, it is difficult to effectively achieve oil-water separation through physical methods such as inertia and centrifugal force. 2. Poor treatment efficiency and stability: Treatment methods without the addition of chemicals often face challenges in terms of treatment efficiency and stability. Since chemical-free treatment methods rely on physical or biological processes, the treatment efficiency is affected and the stability of the system is poor. Summary of the invention

[0004] In view of the defects of the prior art, the present invention provides a Karman vortex street driven oil-containing wastewater oil agglomeration-separation-anti-fouling integrated equipment and design method, which can effectively solve the above problems.

[0005] The technical solution adopted by the present invention is as follows:

[0006] The present invention provides a Karman vortex street driven oil-containing wastewater oil coalescence-separation-anti-fouling integrated equipment, comprising a feed end (1), a vortex street coalescence end (2), an inertia determination end (3), a vortex street reflux end (4) and a negative / positive pressure inertia separation end (5);

[0007] The feed end (1) is in communication with the fluid inlet of the vortex coalescing end (2) and is used to transport the oily wastewater to the vortex coalescing end (2);

[0008] The vortex street coalescing end (2) is used to stimulate the oily wastewater flowing in the flow channel to generate a Karman vortex street effect, and to coalesce the oil droplets in the oily wastewater without adding any chemical agent, so as to coalesce the irregularly dispersed oil droplets in the oily wastewater into regular large oil droplets, thereby obtaining coalesced oily wastewater, and the coalesced oily wastewater is transported to the inertia determination end (3);

[0009] The inertial discrimination end (3) is used to size-screen the oily wastewater after the coalescence treatment by using the inertial focusing effect, and the screened wastewater containing large-sized oil droplets is transported to the negative / positive pressure inertial separation end (5); the oily wastewater from which the large-sized oil droplets are filtered out is transported to the vortex reflux end (4);

[0010] The negative / positive pressure inertial separation end (5) is used to freely adjust the inertial separation mode according to the density of the oil component to achieve oil-water separation, specifically: light oil is assisted by negative pressure to achieve inertial focusing, and heavy oil is assisted by positive pressure to achieve inertial focusing, thereby achieving oil-water separation;

[0011] The vortex reflux end (4) is used to further coalesce the oily wastewater from which large-sized oil droplets have been filtered out, and to transport the treated oily wastewater back to the feed end (1), and then to the vortex coalescing end (2), and this cycle is repeated to perform secondary or multiple coalescing treatments on small-sized oil droplets in the oily wastewater until large-sized oil droplets that are easily separable are formed, and oil-water separation is performed through the negative / positive pressure inertial separation end (5).

[0012] Preferably, the feed end (1), the vortex coalescing end (2), the inertia determination end (3), the vortex reflux end (4) and the negative / positive pressure inertia separation end (5) need to withstand a dynamic water pressure of at least 1 MPa.

[0013] Preferably, the inlet of the feed end (1) is compatible with a variety of feed modes, including gravity injection, pressurized injection and negative pressure suction; and the feed end (1) is a cube.

[0014] Preferably, the vortex street coalescing end (2) comprises a liquid infusion pipeline, in which an array formed by a fixed cylinder and a movable square column is arranged to achieve the induction of a long-distance Karman vortex street; wherein the fixed cylinder and the movable square column are collectively referred to as a vortex street column;

[0015] The liquid infusion pipeline is a serpentine pipeline, which is formed by three sections of liquid infusion pipelines connected in series; according to the direction of water flow, they are respectively: a first section of liquid infusion pipeline (2.1), a second section of liquid infusion pipeline (2.2) and a third section of liquid infusion pipeline (2.3); in the first section of liquid infusion pipeline (2.1), a plurality of the fixed cylinders are arranged at intervals; in the second section of liquid infusion pipeline (2.2), a plurality of the fixed cylinders are arranged at intervals; in the third section of liquid infusion pipeline (2.3), a plurality of the movable square columns are arranged at intervals.

[0016] Preferably, the inertia determination end (3) is an arc-shaped curved pipe branched from the outlet of the vortex street coalescing end (2) and extending upward.

[0017] Preferably, the arc-shaped curved pipe has a curvature radius of 10 cm, an outlet angle of 10°, and a length of 15 cm.

[0018] Preferably, the negative / positive pressure inertial separation end (5) is specifically used for: light oil uses negative pressure to assist oil droplets to float on the water surface and is collected by a top skimming device; heavy oil uses positive pressure to assist oil droplets to settle at the bottom and is collected by a bottom skimming device.

[0019] Preferably, a plurality of movable square columns are arranged at intervals inside the pipe of the vortex return end (4) to stimulate the Karman vortex effect.

[0020] The present invention also provides a design method for the integrated equipment for oily wastewater oil coalescence-separation-antifouling driven by Karman vortex street, comprising the following steps:

[0021] Step 1: Determine fluid parameters and application scenario parameters:

[0022] The fluid parameters include the type and density of oil in the oily wastewater to be treated; the application scenarios are divided into outdoor natural water bodies and indoor static water bodies; the application scenario parameters include: water flow velocity v, water phase dynamic viscosity μ and fluid density ρ; wherein, if it is an outdoor natural water body, the water flow velocity v is the actual water flow velocity of the outdoor natural water body; if it is an indoor static water body, the water flow velocity v is the target water flow velocity;

[0023] Step 2: Determine the boundary conditions for numerical simulation, including: fluid density ρ, water phase dynamic viscosity μ, oil type and feed flow rate V in ; Among them, the feed flow rate V in It is the water velocity v;

[0024] Step 3, constructing a device flow channel geometry model to be optimized; the device flow channel geometry model includes a feed end geometry model, a vortex street coalescence end geometry model, an inertial discrimination end geometry model, a vortex street reflow end geometry model and a negative / positive pressure inertial separation end geometry model;

[0025] The geometric parameters of each component geometric model include geometric parameters to be optimized and fixed geometric parameters;

[0026] The fixed geometric parameters include: the size of the feed end (1); the width, height, number and internal vortex column height of each section of the infusion pipe of the vortex street coalescing end (2); the width, height, radius of curvature and bifurcation angle of the inertial determination end (3); the width and height of the vortex street return end (4); the width, height and length of the negative / positive pressure inertial separation end (5);

[0027] The geometric parameters to be optimized include: the length L of each section of the infusion pipe at the vortex coalescing end (2), the cross-sectional dimension H of the vortex column, the spacing D between the vortex columns, and the number n of vortex columns; wherein, for a fixed cylinder, the cross-sectional dimension H of the vortex column is the cylinder diameter; for a movable square column, the cross-sectional dimension H of the vortex column is the side length of the square; the length of the vortex return end (4) is equal to the length L of each section of the infusion pipe;

[0028] Among them, the central axis of the vortex column is evenly and equidistantly distributed in each section of the infusion pipe; the cross-sectional size H of the vortex column needs to ensure that the Reynolds number is between 1000-2000, therefore, the range of H is determined according to the formula H=Re*μ / (ρ*v), the minimum value of D is determined according to H / 2, and the value of n is determined according to abs(10 / D);

[0029] Step 4, constructing a three-dimensional topology optimization mathematical model of the device flow channel geometric model;

[0030] Step 5, to maximize the vortex shedding frequency f(t -1 ) and helicity as the objective function, under the constraints of the initial conditions and boundary conditions of the numerical simulation, solving the three-dimensional topology optimization mathematical model to obtain the geometric parameters of each component to be optimized that meets the optimization conditions;

[0031] Step 6, according to the obtained geometric parameters of each component, the corresponding equipment components are prepared, including the feed end (1), the vortex street coalescing end (2), the inertial determination end (3), the vortex street reflux end (4) and the negative / positive pressure inertial separation end (5).

[0032] The preferred, maximized helicity formula is as follows:

[0033] H=u·(▽×u) (1)

[0034] in:

[0035] H—helicity m / s 2 , represents the vorticity of the fluid moving in the infusion pipeline;

[0036] u—flow velocity field m / s;

[0037] ▽—gradient operator;

[0038] The three-dimensional topology optimization mathematical model includes a mass conservation equation, a momentum conservation equation and a continuity equation;

[0039] The mass conservation equation is:

[0040]

[0041] The momentum conservation equation is:

[0042] ρ▽·u=0 (3)

[0043] The continuity equation is:

[0044] u·▽c=D0▽ 2 c (4)

[0045] in:

[0046] ▽—Gradient operator, which calculates the gradient of the target variable in each direction;

[0047] ρ—fluid density, kg / m 3 ;

[0048] p—oil-water mixture pressure, pa;

[0049] u—flow velocity field m / s;

[0050] c—oil phase volume fraction, m 3 / m 3 ;

[0051] T—matrix transpose operator;

[0052] I — unit vector;

[0053] μ—dynamic viscosity of water phase, Pa·s;

[0054] α L —Flow field control parameter, the value is 0;

[0055] α U —Flow field control parameter, which takes an infinite value;

[0056] γ—density function design variable;

[0057] q—flow field control parameter to ensure smooth transition of the curve, with a value of 5;

[0058] D0—Diffusion coefficient of dissolved oil in water m / s 2 .

[0059] The invention provides a Karman vortex street driven oily wastewater oil coalescence-separation-anti-fouling integrated equipment and design method, which has the following advantages:

[0060] The present invention can realize the efficient conversion of micro oil droplets into large oil droplets and the precise recovery of large oil droplets. The preparation method of the present invention has a simple process, does not require the addition of chemicals, is safe and environmentally friendly, can be adapted to a variety of oily wastewater treatment scenarios, and fundamentally improves the oil-water separation efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0061] Figure 1 A schematic flow chart of the integrated design method for oily wastewater oil agglomeration-separation-antifouling driven by Karman vortex street provided by the present invention;

[0062] Figure 2 A structural diagram of the integrated equipment for oily wastewater oil coalescence-separation-antifouling provided by the present invention driven by Karman vortex street;

[0063] Figure 3 The vortex street diagram in the optimized flow channel provided by the present invention;

[0064] Figure 4 This is a Reynolds number (Re)-oil removal effect (Cr) relationship diagram provided by the present invention. DETAILED DESCRIPTION

[0065] In order to make the technical problems, technical solutions and beneficial effects solved by the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0066] The invention belongs to the field of drug-free treatment of oily wastewater, and in particular relates to a purely physical vortex-driven oil agglomeration-separation-antifouling integrated device and a design method thereof.

[0067] The present invention provides a Karman vortex street driven oil-containing wastewater oil agglomeration-separation-anti-fouling integrated equipment, which is a systematic device that does not require the addition of chemicals and uses flow field control to strengthen the coalescence of oil droplets and screen and remove them. The device stimulates the Karman vortex street by rationally designing the flow channel, promotes the polymerization of oil droplets with irregular particle sizes, and screens oil droplets with a particle size greater than 1 cm through the inertial focusing effect. Such large-sized oil droplets can be quickly stratified and collected from the water phase under pressure. The device overcomes the problems of uneven oil droplet size, long focusing process, and low collection efficiency in the traditional inertial separation mode. The oil-water separation efficiency is fundamentally improved. In addition, this device does not require the addition of chemicals and microorganisms, avoiding secondary pollution problems and difficult cost control problems.

[0068] The controllable Karman vortex street generating device provided by the present invention makes full use of the movable, high helicity and clear periodic characteristics of the Karman vortex street, solving the low efficiency and high cost problems encountered in the conventional inertial oil-water separation process. Moreover, the unique vortex street shedding characteristics of the Karman vortex street can avoid the pollution problem of the equipment and completely avoid the problem of oil sticking behind the vortex street column. Taking the treatment of industrial oily wastewater in mountainous areas as an example, the equipment can realize the efficient conversion of micro-oil droplets into large oil droplets, as well as the precise recovery of large oil droplets.

[0069] In addition, the equipment has a simple operation process, controllable conditions, and can be driven by gravitational potential energy. Combined with the goal-oriented topological optimization design, the precise design and implementation of a specific oily wastewater treatment process can be achieved, solving the problem of large discreteness of oily wastewater. The preparation method of the present invention has a simple process, does not require the addition of chemicals, is safe and environmentally friendly, and can be adapted to a variety of oily wastewater treatment scenarios.

[0070] See also Figure 2 The present invention provides a Karman vortex street driven oily wastewater oil coalescence-separation-anti-fouling integrated equipment, comprising a feed end 1, a vortex street coalescence end 2, an inertia discrimination end 3, a vortex street reflux end 4 and a negative / positive pressure inertia separation end 5;

[0071] The feed end 1 is connected to the fluid inlet of the vortex street coalescing end 2, and is used to transport the oily wastewater to the vortex street coalescing end 2;

[0072] The vortex street coalescing end 2 is used to stimulate the oily wastewater flowing in the flow channel to generate a Karman vortex street effect, and to coalesce the oil droplets in the oily wastewater without adding any chemical agent, so as to coalesce the irregularly dispersed oil droplets in the oily wastewater into regular large oil droplets to obtain coalesced oily wastewater, and the coalesced oily wastewater is transported to the inertia determination end 3;

[0073] The inertial discrimination end 3 is used to size-screen the oily wastewater after the coalescence treatment by using the inertial focusing effect, and the screened wastewater containing large-sized oil droplets is transported to the negative / positive pressure inertial separation end 5; the oily wastewater with large-sized oil droplets filtered out is transported to the vortex street reflux end 4;

[0074] The negative / positive pressure inertial separation end 5 is used to freely adjust the inertial separation mode according to the density of the oil component to achieve oil-water separation, specifically: light oil is assisted by negative pressure to achieve inertial focusing, and heavy oil is assisted by positive pressure to achieve inertial focusing, thereby achieving oil-water separation;

[0075] The vortex reflux end 4 is used to further coalesce the oily wastewater from which large-sized oil droplets have been filtered out, and to transport the treated oily wastewater back to the feed end 1, and then to the vortex coalescing end 2, and this cycle is continued to perform secondary or multiple coalescing treatments on small-sized oil droplets in the oily wastewater until large-sized oil droplets that are easily separable are formed, and oil-water separation is performed through the negative / positive pressure inertial separation end 5.

[0076] The feed end 1, the vortex coalescing end 2, the inertial discrimination end 3, the vortex reflux end 4 and the negative / positive pressure inertial separation end 5 have no requirements on materials, but have requirements on material strength, and must withstand a dynamic water pressure of at least 1 MPa.

[0077] The inlet of the feed end 1 is compatible with a variety of feed modes, including gravity injection, pressurized injection and negative pressure suction; the feed end 1 is a cube with a side length of 1 meter.

[0078] The vortex street coalescing end 2 includes a liquid infusion pipeline, in which an array formed by a fixed cylinder and a movable square column is arranged to achieve the induction of a long-distance Karman vortex street; wherein the fixed cylinder and the movable square column are collectively referred to as a vortex street column;

[0079] Wherein: the infusion pipeline is a serpentine pipeline, which is formed by three sections of infusion pipes connected in series; according to the direction of water flow, they are respectively: the first section of the infusion pipe 2.1, the second section of the infusion pipe 2.2 and the third section of the infusion pipe 2.3; the length of each section of the infusion pipe is 1.5m, the width is 30cm, and the height is 1m. In the first section of the infusion pipe 2.1, multiple fixed cylinders are arranged at intervals; in the second section of the infusion pipe 2.2, multiple fixed cylinders are arranged at intervals; in the third section of the infusion pipe 2.3, multiple movable square columns are arranged at intervals. Therefore, the three sections of the infusion pipe respectively use fixed cylinders, fixed cylinders and movable square columns to excite the Karman vortex street, and the width and diameter of the vortex street column are calculated and determined according to the design method. The distance between the axis of the vortex street column and the water inlet of the vortex street coalescing end 2 is 8cm. The principle is that as the Reynolds number Re decreases, the excitation of the Karman vortex street requires the obstacle itself to provide oscillation excitation.

[0080] The inertia determination end 3 is an arc-shaped curved pipe branched upward from the outlet of the vortex street coalescing end 2 to achieve the screening of large-sized oil droplets. The arc-shaped curved pipe has a curvature radius of 10 cm, an outlet angle of 10°, and a length of 15 cm.

[0081] The negative / positive pressure inertial separation end 5 can freely adjust the inertial separation mode according to the density of the oil component. Specifically, it is used for: light oil uses negative pressure to assist oil droplets to float on the water surface and is collected by the top skimming device; heavy oil uses positive pressure to assist oil droplets to settle at the bottom and is collected by the bottom skimming device. The width, height and length of the negative / positive pressure inertial separation end 5 are 30cm, 1m, and 50cm.

[0082] The vortex return end 4 is structurally equivalent to the last section of the infusion tube of the vortex coalescing end 2, and uses movable square columns inside to excite the Karman vortex street, that is, a plurality of movable square columns are arranged at intervals inside the pipeline of the vortex return end 4 to excite the Karman vortex street effect.

[0083] See also Figure 1 The present invention also provides a design method for an integrated equipment for oily wastewater oil coalescence-separation-antifouling driven by a Karman vortex street, comprising the following steps:

[0084] Step 1: Determine fluid parameters and application scenario parameters:

[0085] The fluid parameters include the type and density of oil in the oily wastewater to be treated; the application scenarios are divided into outdoor natural water bodies and indoor static water bodies; the application scenario parameters include: water flow velocity v, water phase dynamic viscosity μ and fluid density ρ; wherein, if it is an outdoor natural water body, the water flow velocity v is the actual water flow velocity of the outdoor natural water body; if it is an indoor static water body, the water flow velocity v is the target water flow velocity;

[0086] Step 2: Determine the boundary conditions for numerical simulation, including: fluid density ρ, water phase dynamic viscosity μ, oil type and feed flow rate V in ; Among them, the feed flow rate V in It is the water velocity v;

[0087] Step 3, constructing a device flow channel geometry model to be optimized for subsequent numerical simulation and parameter optimization; the device flow channel geometry model to be optimized includes all components of the aforementioned Karman vortex street driven oily wastewater oil coalescence-separation-antifouling integrated equipment, that is, the device flow channel geometry model includes a feed end geometry model, a vortex street coalescence end geometry model, an inertial discrimination end geometry model, a vortex street reflow end geometry model and a negative / positive pressure inertial separation end geometry model;

[0088] The geometric parameters of each component geometric model include geometric parameters to be optimized and fixed geometric parameters;

[0089] The fixed geometric parameters include: the size of the feed end 1; the width, height, number of each section of the infusion pipe of the vortex street coalescing end 2 and the height of the internal vortex street column; the width, height, curvature radius and bifurcation angle of the inertial discrimination end 3; the width and height of the vortex street return end 4; the width, height and length of the negative / positive pressure inertial separation end 5;

[0090] The geometric parameters to be optimized include: the length L of each section of the infusion pipe at the vortex street coalescing end 2, the cross-sectional size H of the vortex street column, the spacing D between the vortex street columns, and the number n of vortex street columns; wherein, for a fixed cylinder, the cross-sectional size H of the vortex street column is the cylinder diameter; for a movable square column, the cross-sectional size H of the vortex street column is the side length of the square; the length of the vortex street return end 4 is equal to the length L of each section of the infusion pipe;

[0091] Among them, the central axis of the vortex column is evenly and equidistantly distributed in each section of the infusion pipe; the cross-sectional size H of the vortex column needs to ensure that the Reynolds number is between 1000-2000, therefore, the range of H is determined according to the formula H=Re*μ / (ρ*v), the minimum value of D is determined according to H / 2, and the value of n is determined according to abs(10 / D);

[0092] Step 4: construct a three-dimensional topology optimization mathematical model of the device flow channel geometry model to obtain the maximum vortex shedding frequency f(t -1 ) and helicity as the objective function, and use CFD software to bring the flow velocity, fluid dynamics parameters and initial conditions and boundary conditions of numerical simulation in step 1 into the device flow channel geometry model to be optimized in step 3 to establish a three-dimensional topology optimization mathematical model.

[0093] The three-dimensional topology optimization mathematical model includes a mass conservation equation, a momentum conservation equation and a continuity equation;

[0094] The mass conservation equation is:

[0095]

[0096] The momentum conservation equation is:

[0097] ρ▽·u=0 (3)

[0098] The continuity equation is:

[0099] u·▽c=D0▽ 2 c (4)

[0100] in:

[0101] ▽—Gradient operator, which calculates the gradient of the target variable in each direction;

[0102] ρ—fluid density, kg / m 3 ;

[0103] p—oil-water mixture pressure, pa;

[0104] u—flow velocity field m / s;

[0105] c—oil phase volume fraction, m 3 / m 3 ;

[0106] T—matrix transpose operator;

[0107] I — unit vector;

[0108] μ—dynamic viscosity of water phase, Pa·s;

[0109] α L —Flow field control parameter, the value is 0;

[0110] α U —Flow field control parameter, which takes an infinite value;

[0111] γ—density function design variable;

[0112] q—flow field control parameter to ensure smooth transition of the curve, with a value of 5;

[0113] D0—Diffusion coefficient of dissolved oil in water m / s 2 .

[0114] Step 5, to maximize the vortex shedding frequency f(t -1 ) and helicity as the objective function, under the constraints of the initial conditions and boundary conditions of the numerical simulation, the three-dimensional topology optimization mathematical model is solved to obtain the geometric parameters of each component to be optimized that meets the optimization conditions; specifically, the width and diameter of the vortex column to be optimized are determined by using CFD software according to the three-dimensional topology optimization mathematical model of step 4, and the optimized three-dimensional topological structure of the equipment flow channel is obtained;

[0115] The formula for maximizing the helicity is as follows:

[0116] H=u·(▽×u) (1)

[0117] in:

[0118] H—helicity m / s 2 , represents the vorticity of the fluid moving in the infusion pipeline;

[0119] u—flow velocity field m / s;

[0120] ▽—gradient operator;

[0121] Step 6, according to the obtained geometric parameters of each component, the corresponding equipment components are prepared, including the feed end 1, the vortex street coalescing end 2, the inertial discrimination end 3, the vortex street reflux end 4 and the negative / positive pressure inertial separation end 5. Specifically, the three-dimensional topology optimization mathematical model of step 4 is output in the stl. file format, and is prepared and installed according to the designed geometric model structure.

[0122] The device flow channel structure designed in step 5 is prepared, wherein the flow channel wall thickness and material must be able to withstand at least 1 MPa pressure. The designed device is used for rapid oil droplet coalescence and collection without drug drive.

[0123] An embodiment is described below:

[0124] This embodiment is a Karman vortex street driven oil-containing wastewater oil agglomeration-separation-anti-pollution integrated equipment for treating industrial oil-containing wastewater in mountainous areas.

[0125] Reference Figure 1 As shown, a design method for an integrated equipment for oily wastewater oil coalescence-separation-antifouling driven by a Karman vortex street is shown, and the specific steps are as follows:

[0126] Step 1: Determine the application scenario and fluid parameters, including application scenario, fluid density, viscosity, and feed flow rate information.

[0127] Step 2: Determine the boundary conditions of the numerical model:

[0128] Determine the fluid density ρ (1×10 3 kg / m 3 ), dynamic viscosity μ(1×10 3 ); Oil type (light oil, silicone oil 20) according to the processing efficiency requirements, determine the feed flow rate V in (10cm / s) and the other boundaries are zero flux boundaries.

[0129] Step 3: Establish flow channel topology optimization model

[0130] Establishing the geometric model and mathematical model of 3D topology optimization includes the following steps:

[0131] (3a) Construct the model to be optimized and determine the area to be optimized and the geometric parameters. This can be constructed using Soildwork software. Figure 2 The flow channel model described is exported as stl. file for subsequent numerical analysis.

[0132] (3b) According to the internal flow field requirements of the equipment, the maximum vortex shedding frequency and helicity (Formula 1) are selected as the topology optimization objective function.

[0133] H=u·(▽×u) (1)

[0134] in:

[0135] H—helicity (m / s 2 );

[0136] u—flow velocity field (m / s).

[0137] (3c) Based on the topology optimization method and the above-mentioned geometric model, a three-dimensional topology optimization mathematical model (including numerical model control equations, boundary conditions, inlet flow velocity and fluid dynamics parameters) is established using the mass conservation equation, momentum conservation equation and continuity equation. Among them, the mass conservation equation of the area to be optimized is rewritten as formula 3-2:

[0138] ρ(u·▽)u=▽·[-pI+μ(▽u+(▽u) T )] (3-1)

[0139]

[0140] ρ▽·u=0 (4)

[0141] u·▽c=D0▽ 2 c (5)

[0142] in:

[0143] ▽—Gradient operator, which calculates the gradient of the target variable in each direction;

[0144] ρ—Fluid density (kg / m 3 );

[0145] p—oil-water mixture pressure (pa);

[0146] u——flow velocity field m / s;

[0147] T—matrix transpose operator;

[0148] I — unit vector;

[0149] μ—dynamic viscosity of water (Pa·s);

[0150] α L —Flow field control parameter, the value is 0;

[0151] α U —Flow field control parameter, which takes an infinite value;

[0152] γ—density function design variable;

[0153] q—Flow field control parameter to ensure smooth transition of the curve, with a value of 5.

[0154] D0—Diffusion coefficient of dissolved oil in water m / s 2 .

[0155] Step 4: Solve the three-dimensional topology optimization model through finite element analysis to obtain the flow channel topology structure

[0156] (4a) According to the three-dimensional topology optimization mathematical model established in step (3), finite element meshing is performed using a mapped mesh.

[0157] (4b) Select the topology optimization iterative algorithm. Here, the adjoint method is used to solve the sensitivity. The moving progressive algorithm MMA is selected as the optimization iterative algorithm. The maximum number of iterations is set to 500. The optimization iteration termination condition is: |F k+1 -F k |≤10 -6 , where F k is the objective function value obtained at the kth iteration, and k is the number of iterations.

[0158] (4c) The density filtering and projection method in the form of Holmz partial differential equation is used to solve the checkerboard phenomenon and grayscale units in the topological structure, and at the same time introduce a minimum size constraint in the filtering radius. The density filtering expression in the form of Holmz partial differential equation is as follows:

[0159]

[0160] in:

[0161] r—filter radius, used to introduce minimum size constraints;

[0162] —Filtered density function design variables

[0163] γ — density function design variable.

[0164] In order to reduce the grayscale units, hyperbolic tangent projection is used here to obtain a clear topological structure. The expression is as follows:

[0165]

[0166] in:

[0167] ——Design variables of density function after projection;

[0168] η——projection point;

[0169] β – slope;

[0170] Step 5: Output the optimized flow channel geometry model:

[0171] (5a) Re-grid the topology optimization results and solve the filter variables on a finer grid;

[0172] (5b) The optimization result is filtered and output, and the filtered variables are processed in the following manner:

[0173]

[0174] Among them, γ is the filtering variable (density function design variable);

[0175] (5c) Based on the output results, a three-dimensional geometric model of the optimized flow channel is established in the CAD software according to the actual size parameters of the optimized flow channel.

[0176] Step 6: Extract the velocity field u and pressure field p distribution inside the optimized flow channel and draw a streamline diagram. Figure 3 The flow patterns inside the flow channel before and after optimization are given, providing a basis for subsequent judgment on whether the performance meets the requirements.

[0177] Step 7, based on the vortex shedding frequency and helicity, determine whether the standard of the mass transfer design target supplementary index is met.

[0178] Step 8, preparing the oil agglomeration-separation-antifouling integrated equipment according to the optimized equipment flow channel structure design scheme.

[0179] Step 9, performance test and oil-water separation operation:

[0180] (1) Vortex test. It has been verified that the device constructed in this embodiment can generate high-frequency vortex shedding inside to form a movable high-speed vortex. 90% of the micro-oil droplets can be coalesced into large-sized oil droplets with a particle size greater than 1 cm within 5 cycles.

[0181] (2) Oil recovery capability test. It has been verified that large oil droplets stably accumulate on the liquid surface in the negative / positive pressure inertial separation end and can be recovered through a simple skimming process. According to calculations, the oil phase recovery rate can reach 97%. If further treatment is required, electrochemical deep treatment can be directly carried out in the negative / positive pressure inertial separation end.

[0182] The present invention flexibly utilizes the high vorticity, mobility, regularity and high frequency characteristics of the vortex of the Karman vortex street, transforms the traditional passive static inertial oil-water separation scheme into a dynamic first-agglomeration-then-recovery scheme, and realizes the harmonious combination of centrifugation, inertial focusing and mechanical recovery. The effect of 1+1>2 is achieved, and an application example is given. The present invention is not limited to the treatment of industrial oily wastewater in mountainous areas, but can also be applied to various application scenarios such as urban industrial plants, sewage treatment plants, and marine oil leakage control.

[0183] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be considered as the scope of protection of the present invention.

Claims

1. A Karman vortex street driven oily wastewater oil coalescence-separation-anti-fouling integrated equipment, characterized in that: It includes a feed end (1), a vortex street coalescence end (2), an inertia determination end (3), a vortex street reflux end (4) and a negative / positive pressure inertia separation end (5); The feed end (1) is in communication with the fluid inlet of the vortex coalescing end (2) and is used to transport the oily wastewater to the vortex coalescing end (2); The vortex street coalescing end (2) is used to stimulate the oily wastewater flowing in the flow channel to generate a Karman vortex street effect, and to coalesce the oil droplets in the oily wastewater without adding any chemical agent, so as to coalesce the irregularly dispersed oil droplets in the oily wastewater into regular large oil droplets, thereby obtaining coalesced oily wastewater, and the coalesced oily wastewater is transported to the inertia determination end (3); The inertial discrimination end (3) is used to size-screen the oily wastewater after the coalescence treatment by using the inertial focusing effect, and the screened wastewater containing large-sized oil droplets is transported to the negative / positive pressure inertial separation end (5); the oily wastewater from which the large-sized oil droplets are filtered out is transported to the vortex reflux end (4); wherein: the inertial discrimination end (3) is an arc-shaped curved pipe branched from the outlet of the vortex coalescence end (2) and led upward; The negative / positive pressure inertial separation end (5) is used to freely adjust the inertial separation mode according to the density of the oil component to achieve oil-water separation, specifically: light oil is assisted by negative pressure to achieve inertial focusing, and heavy oil is assisted by positive pressure to achieve inertial focusing, thereby achieving oil-water separation; The vortex reflux end (4) is used to further coalesce the oily wastewater from which large-sized oil droplets have been filtered out, and to transport the treated oily wastewater back to the feed end (1), and then to the vortex coalescing end (2), and this cycle is repeated to perform secondary or multiple coalescing treatments on small-sized oil droplets in the oily wastewater until large-sized oil droplets that are easily separable are formed, and oil-water separation is performed through the negative / positive pressure inertial separation end (5).

2. The integrated equipment for oily wastewater coalescence-separation-antifouling driven by Karman vortex street according to claim 1, characterized in that: The feed end (1), the vortex coalescing end (2), the inertia determination end (3), the vortex reflux end (4) and the negative / positive pressure inertia separation end (5) need to withstand a dynamic water pressure of at least 1 MPa.

3. The integrated equipment for oily wastewater coalescence-separation-antifouling driven by Karman vortex street according to claim 1, characterized in that: The inlet of the feed end (1) is compatible with a variety of feeding modes, including gravity injection, pressurized injection and negative pressure suction; The feed end (1) is in the shape of a cube.

4. The integrated equipment for oily wastewater coalescence-separation-antifouling driven by Karman vortex street according to claim 1, characterized in that: The vortex street coalescing end (2) comprises a liquid infusion pipeline, in which an array formed by a fixed cylinder and a movable square column is arranged for inducing a long-distance Karman vortex street; wherein the fixed cylinder and the movable square column are collectively referred to as vortex street columns; The liquid infusion pipeline is a serpentine pipeline, which is formed by three sections of liquid infusion pipelines connected in series; according to the direction of water flow, they are respectively: a first section of liquid infusion pipeline (2.1), a second section of liquid infusion pipeline (2.2) and a third section of liquid infusion pipeline (2.3); in the first section of liquid infusion pipeline (2.1), a plurality of the fixed cylinders are arranged at intervals; in the second section of liquid infusion pipeline (2.2), a plurality of the fixed cylinders are arranged at intervals; in the third section of liquid infusion pipeline (2.3), a plurality of the movable square columns are arranged at intervals.

5. The integrated equipment for oily wastewater coalescence-separation-antifouling driven by Karman vortex street according to claim 1, characterized in that: The curvature radius of the arc-shaped curved pipe is 10 cm, the outlet angle is 10°, and the length is 15 cm.

6. The integrated equipment for oily wastewater coalescence-separation-antifouling driven by Karman vortex street according to claim 1, characterized in that: The negative / positive pressure inertial separation end (5) is specifically used for: light oil uses negative pressure to assist oil droplets to float on the water surface and be collected by a top skimming device; heavy oil uses positive pressure to assist oil droplets to settle at the bottom and be collected by a bottom skimming device.

7. The integrated equipment for oily wastewater coalescence-separation-antifouling driven by Karman vortex street according to claim 1, characterized in that: A plurality of movable square columns are arranged at intervals inside the pipe of the vortex return end (4) to stimulate the Karman vortex effect.

8. A method for designing an integrated equipment for oily wastewater coalescence-separation-antifouling driven by Karman vortex street according to any one of claims 1 to 7, characterized in that: The following steps are involved: Step 1: Determine fluid parameters and application scenario parameters: The fluid parameters include the type and density of oil in the oily wastewater to be treated; The application scenarios are divided into outdoor natural water bodies and indoor static water bodies; The application scenario parameters include: water flow velocity v, water phase dynamic viscosity μ and fluid density ρ; wherein, if it is an outdoor natural water body, the water flow velocity v is the actual water flow velocity of the outdoor natural water body; if it is an indoor static water body, the water flow velocity v is the target water flow velocity; Step 2: Determine the boundary conditions for numerical simulation, including: fluid density ρ, water phase dynamic viscosity μ, oil type and feed flow rate V in ; Among them, the feed flow rate V in It is the water velocity v; Step 3, constructing a device flow channel geometry model to be optimized; the device flow channel geometry model includes a feed end geometry model, a vortex street coalescence end geometry model, an inertial discrimination end geometry model, a vortex street reflow end geometry model and a negative / positive pressure inertial separation end geometry model; The geometric parameters of each component geometric model include geometric parameters to be optimized and fixed geometric parameters; The fixed geometric parameters include: the size of the feed end (1); the width, height, number and internal vortex column height of each section of the infusion pipe of the vortex street coalescing end (2); the width, height, radius of curvature and bifurcation angle of the inertial determination end (3); the width and height of the vortex street return end (4); the width, height and length of the negative / positive pressure inertial separation end (5); The geometric parameters to be optimized include: the length L of each section of the infusion pipe at the vortex coalescing end (2), the cross-sectional dimension H of the vortex column, the spacing D between the vortex columns, and the number n of vortex columns; wherein, for a fixed cylinder, the cross-sectional dimension H of the vortex column is the cylinder diameter; for a movable square column, the cross-sectional dimension H of the vortex column is the side length of the square; the length of the vortex return end (4) is equal to the length L of each section of the infusion pipe; Among them, the central axis of the vortex column is evenly and equidistantly distributed in each section of the infusion pipe; the cross-sectional size H of the vortex column needs to ensure that the Reynolds number is between 1000-2000, therefore, the range of H is determined according to the formula H=Re*μ / (ρ*v), the minimum value of D is determined according to H / 2, and the value of n is determined according to abs(10 / D); Step 4, constructing a three-dimensional topology optimization mathematical model of the device flow channel geometric model; Step 5, to maximize the vortex shedding frequency f(t -1 ) and helicity as the objective function, under the constraints of the initial conditions and boundary conditions of the numerical simulation, solving the three-dimensional topology optimization mathematical model to obtain the geometric parameters of each component to be optimized that meets the optimization conditions; Step 6, according to the obtained geometric parameters of each component, the corresponding equipment components are prepared, including the feed end (1), the vortex street coalescing end (2), the inertial determination end (3), the vortex street reflux end (4) and the negative / positive pressure inertial separation end (5).

9. The design method of the integrated equipment for oily wastewater coalescence-separation-antifouling driven by Karman vortex street according to claim 8, characterized in that: The formula for maximizing helicity is as follows: in: H—helicity m / s 2 , represents the vorticity of the fluid moving in the infusion pipeline; u—flow velocity field m / s; ▽—gradient operator; The three-dimensional topology optimization mathematical model includes a mass conservation equation, a momentum conservation equation and a continuity equation; The mass conservation equation is: The momentum conservation equation is: The continuity equation is: in: —Gradient operator, which calculates the gradient of the target variable in each direction; ρ—fluid density, kg / m 3 ; p—oil-water mixture pressure, pa; u—flow velocity field m / s; c—oil phase volume fraction, m 3 / m 3 ; T—matrix transpose operator; I — unit vector; μ—dynamic viscosity of water phase, Pa·s; α L —Flow field control parameter, the value is 0; α U —Flow field control parameter, which takes an infinite value; γ—density function design variable; q—flow field control parameter to ensure smooth transition of the curve, with a value of 5; D0—diffusion coefficient of dissolved oil in water m / s 2 .

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