Device and method for generating double droplet forward and reverse phase enhanced extraction and oil removal

Abstract

The present invention provides a device and method for generating double droplet forward and reverse phase enhanced extraction and oil removal, comprising a forward phase dispersion extraction device and a reverse phase extraction separation device, wherein the forward phase dispersion extraction device mainly comprises a jet dispersion unit and a turbulent mixing unit, and the reverse phase extraction separation device comprises a double droplet dispersion unit and a cooperative separation unit. The extractant is sprayed and dispersed in the oily wastewater, and undergoes multi-stage turbulent mixing to form an oil-water mixture, which is then dispersed in the extractant phase to generate large-particle double droplets to further enhance the extraction process of the dissolved oil. After the extractant droplets are released through the oil-water interface, deep phase separation is achieved through a multi-media coalescence bed. The present invention solves the problem of difficult removal of emulsified oil and dissolved oil in traditional oil removal devices, and the device has a compact structure, great operational flexibility, and low energy consumption, and can realize resource recovery of multi-form oils in oily wastewater.

Description

Technical Field

[0001] The present invention belongs to the technical field of oily wastewater treatment in petrochemical industry, coal chemical industry, coking, mechanical processing and the like, and specifically relates to a device and method for generating double droplet forward and reverse phase enhanced extraction and oil removal. Background Art

[0002] Large quantities of oily wastewater are generated in many units in the fields of petrochemicals, coal chemical industry, coking, and mechanical processing. The oil in oily wastewater exists in the form of dispersed oil, emulsified oil, and dissolved oil. Dissolved oil refers to organic compounds with a certain solubility in water. Conventional methods for treating oily wastewater currently mainly involve adding chemical agents to break the emulsion, combined with traditional equipment such as inclined plates, cyclones, and flotation. These treatment methods are mainly effective for treating dispersed and emulsified oils, but they also have the problems of large dosages, large land areas, and high production of hazardous waste scum. The treatment effect on dissolved and highly emulsified oils is poor, and the oil concentration in the effluent after treatment is too high, often requiring further deep oil removal.

[0003] CN201710079809.1 discloses a method and device for resource utilization of oilfield produced water, which uses a dissolved air flotation and immobilized microbial pool combination device to remove soluble oil. However, the combined device has a long process, occupies a large area, and introduces the problem of hazardous sludge waste.

[0004] CN202220915929.7 discloses an integrated device for separating and filtering oily wastewater. The removal of dissolved oil is mainly achieved by adsorbing the dissolved oil in the wastewater through the filter filler. However, the device has a short treatment cycle, a low dirt holding capacity of the filler, and is easily saturated with adsorption.

[0005] CN202210767828.4 discloses a flotation and extraction treatment system and method for oil-containing wastewater in an oil-water separation device based on partial vaporization of low-boiling-point liquid. It mainly utilizes the flotation and similar phase extraction process of low-boiling-point liquid to separate dissolved oil, but the device has high energy consumption and the oil removal effect of the flotation process without adding drugs is poor.

[0006] Therefore, in order to address the problem that the dissolved oil content in oily wastewater treated by conventional methods is high and the effluent water quality is unqualified, it is of great significance to provide a device and method for generating double droplet positive and negative phase enhanced extraction and oil removal to achieve efficient phase separation of dissolved oil and extractant. Summary of the Invention

[0007] In response to the shortcomings of the existing technology, the present invention provides a device and method for generating double droplet positive and negative phase enhanced extraction and oil removal, which utilizes the combination of dispersed mixing of extractant droplets and hydrophilic and hydrophobic material separation bed layers, as well as the phase interface conversion of the dispersed phase and the continuous phase to enhance extraction mass transfer, thereby achieving efficient phase separation of dissolved oil and extractant, reducing the oil content in the effluent, and realizing resource recovery of organic matter in the water and wastewater detoxification.

[0008] In order to achieve the above-mentioned object of the invention, the technical solution adopted by the present invention is:

[0009] A device for double droplet forward and reverse phase enhanced extraction and oil removal, comprising a forward phase dispersion extraction device and a reverse phase extraction separation device connected in sequence, wherein:

[0010] The normal phase dispersion extraction device is provided with an oily wastewater inlet at one end and a mixed liquid outlet at the other end. A spray dispersion unit and a turbulent mixing unit are sequentially arranged inside along the material flow direction. The side wall of the spray dispersion unit is provided with an extractant inlet.

[0011] The upper part of the reverse-phase extraction separation device is provided with a mixed liquid inlet connected to the mixed liquid outlet, and the top and bottom are respectively provided with an extractant outlet and a purified water outlet. A double droplet dispersion unit and a cooperative separation unit are sequentially arranged inside along the material flow direction. The extractant outlet is connected to the extractant inlet for extractant reflux to perform multi-stage extraction.

[0012] The present invention is further configured such that the injection dispersion unit is a plurality of units repeatedly arranged in parallel, a single injection dispersion unit is a Venturi structure, comprising a necking section, a throat and a dispersion section connected in sequence, a plurality of injectors are evenly arranged circumferentially in the throat or radially in the necking section, the aperture of the injector is 0.2 to 6 mm, and can be set to multiple according to the dispersed phase flow rate, the tapering angle α of the necking section and the diverging angle β of the dispersion section of the Venturi structure are 10° to 25°, and the aspect ratio of the throat is 0.5 to 2.

[0013] The present invention is further configured such that the turbulent mixing unit is a plurality of units repeatedly arranged in parallel, and a single turbulent mixing unit is a cylindrical structure, comprising a turbulent mixing shell and a multi-stage repeatedly arranged mixing structure arranged in the turbulent mixing shell, and each stage of the mixing structure comprises a first mixing section and two second mixing sections.

[0014] Furthermore, the first mixing section and the second mixing section are both irregular triangular prism structures, and their cross-sectional shapes in the horizontal axial section passing through the turbulent mixing unit are irregular triangles formed by circumscribing three equal circles with radii r1 and r2, respectively, r1 is 0.4 to 0.6 times the diameter d of the turbulent mixing unit, and r2 is 0.2 to 0.35 times d; the first mixing section and the second mixing section are arranged in an equilateral triangle, and the horizontal sections of the first mixing section and the two second mixing sections are arranged with their vertices facing each other and their bases facing back to back; the axial center distance l of the two second mixing sections in each mixing structure is 0.4 to 0.6 times d.

[0015] The present invention is further configured such that the double droplet dispersion unit includes a liquid distributor connected to the mixed liquid inlet, and a plurality of Venturi dispersion devices are provided at the outlet of the liquid distributor, wherein the Venturi dispersion devices include a tapered section, a suction section, and a gradually expanding section in sequence along the material flow direction, and a plurality of suction holes are provided in the radial direction of the suction section; the diameter of the suction section is 5 to 30 mm, the aspect ratio is 5 to 7, the diameter of the suction hole is 1 to 5 mm, and the tapered angle of the tapered section and the gradually expanding angle of the gradually expanding section are 10° to 25°.

[0016] Furthermore, the Venturi dispersion device is evenly distributed along the circumference at the bottom of the liquid distributor.

[0017] The present invention is further configured as follows: the collaborative separation unit includes a multi-media coalescing bed and an oil collecting pipe passing through the multi-media coalescing bed; the distance between the multi-media coalescing bed and the double droplet dispersion unit is preferably set to 50 to 70 cm; the multi-media coalescing bed is a medium coalescing bed filled with media of different morphologies and / or hydrophilic and hydrophobic properties; the filled media include granular media and / or fibrous media, wherein the granular media are spherical or irregular particles with a particle size range of 0.5 to 5 mm, and the fibrous media are fiber filaments with a diameter range of 10 to 500 μm; the bed porosity of the multi-media coalescing bed is 0.5 to 0.85, and the bed depth is 1000 to 2000 mm.

[0018] The present invention is further configured such that the reverse-phase extraction separation device includes an interface control system, the interface control system includes an interface meter, a PLC control system, and control valves respectively located at the purified water outlet and the extractant outlet, the interface meter and the control valve are both connected to the PLC control system, the purified water outlet and the extractant outlet are automatically controlled by interface-control valve linkage, and are located between the dual droplet dispersion unit and the collaborative separation unit through the oil-water interface, preferably controlled 5-15 cm above the multi-media coalescing bed.

[0019] A second object of the present invention is to provide a method for oil removal using the above-mentioned device for generating double droplet forward and reverse phase enhanced extraction and oil removal, which specifically comprises the following steps:

[0020] (1) The oily wastewater enters the jet dispersion unit of the normal phase dispersion extraction device, and the extractant is injected into the jet dispersion unit and dispersed in the oily wastewater through the venturi structure to form a mixed liquid;

[0021] (2) The mixed liquid enters the turbulent mixing unit, where micro-swirl and turbulent fragmentation processes are carried out alternately in multiple stages to enhance the interphase transfer process of organic matter in the mixed liquid.

[0022] (3) The mixed liquid after turbulent mixing enters the double droplet dispersion unit in the reverse phase extraction separation device. After uniform liquid distribution, it is sprayed into the extractant phase through the Venturi dispersion device and the external extractant is sucked into the tube to produce "oil-in-water-in-oil" double droplets for further reverse phase dispersion extraction.

[0023] (4) The double droplets release the extractant droplets again after passing through the oil-water interface. Some of the extractant droplets float up and separate directly, while the unseparated extractant droplets enter the cooperative separation unit and further coalesce and grow in the multi-media coalescing bed. Some of the extractant droplets in the media bed float up and merge into the extractant layer for separation, while some of the extractant droplets flow to the bottom of the media bed and then float up through the oil collecting pipe and merge into the extractant layer for separation;

[0024] (5) The purified water separated by the collaborative separation unit is discharged from the purified water outlet at the bottom and enters the next process, or enters the next process after deep removal of the extractant (secondary extraction or evaporation, etc.); the extractant is discharged from the top extractant outlet, a part of which is refluxed to the spray dispersion unit, and the other part is recovered for treatment.

[0025] The present invention is further configured such that the extractant is selected from one or more of low-boiling-point oils and benzene series products in petroleum processing and coal chemical by-products.

[0026] The present invention is further configured such that, according to the change in the content of emulsified oil and dissolved oil in the oily wastewater, the feed volume ratio of the extractant to the oily wastewater is (1-20):100.

[0027] The present invention is further configured such that in step (1), the particle size distribution of the extractant passing through the jet dispersion unit is 20 to 100 μm, and the size of the dispersed particle size can be adjusted by the jet pressure and the main phase flow rate; in step (2), the particle size distribution of the extractant passing through the turbulent mixing unit is 5 to 80 μm; and the average flow rate of the jet dispersion section and the turbulent mixing section is 0.3 to 5 m / s.

[0028] The present invention is further configured such that the water droplet particle size in the double droplets dispersed and generated by the double droplet dispersion unit in step (3) is 0.2 to 2 mm; the cross-sectional flow rate in the multi-media coalescing bed layer of the collaborative separation unit in step (4) is 0.001 to 0.03 m / s. After being processed by the collaborative separation unit, all extractant droplets with a particle size of 50 μm or more can float and separate, and the removal rate of extractant droplets with a size of 5 μm or more exceeds 99%.

[0029] The present invention is further configured such that, in the extractant after oil-water separation in step (5), the ratio of the reflux extractant to the recovered extractant is (0.5-20):1; the reflux extractant and the fresh extractant are mixed and injected into the injection dispersion unit, and the injection ratio of the reflux extractant to the fresh extractant is (0.2-20):1.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] (1) The present invention provides an apparatus and method for generating double droplet forward and reverse phase enhanced extraction and oil removal, which can generate extractant droplets and double droplets with controllable particle size, achieve efficient phase separation while ensuring mass transfer effect, shorten the contact time between the two phases, can be operated continuously, and can be arranged in series and parallel, with high operational flexibility.

[0032] (2) The present invention uses oil or benzene series products from petroleum processing or coal chemical by-products as extraction agents, which can reduce costs. Combined with double droplet extraction technology, it can reduce extraction agent consumption and has good economic benefits.

[0033] (3) Compared with traditional extraction towers and mixing and settling tank technologies, the device of the present invention has a compact structure and low energy consumption. It can obtain a larger mass transfer area under the same extractant conditions by generating double droplets, and can achieve efficient phase separation of the extractant through the coordinated cooperation of subsequent separation modules. It is particularly suitable for the separation and treatment of highly soluble oil in oily wastewater and the resource recovery of difficult-to-separate oil. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 This is a flow chart of the device for generating double droplet forward and reverse phase enhanced extraction and oil removal according to the present invention;

[0035] Figure 2 It is a structural schematic diagram of the spray dispersion unit of the present invention;

[0036] Figure 3 It is a structural schematic diagram of the spray dispersion unit of the present invention;

[0037] Figure 4 Schematic diagram of the structure of the turbulent mixing unit of the present invention (the turbulent mixing housing is not shown);

[0038] Figure 5 A partial cross-sectional view of a turbulent mixing unit of the present invention (showing only a single-stage mixing structure);

[0039] Figure 6 Schematic diagram of the structure of the double droplet dispersion unit of the present invention;

[0040] Figure 7 is a distribution diagram of the Venturi dispersion device of the present invention;

[0041] Figure 8 This is a schematic diagram showing the principle of enhanced capture of emulsified oil and dissolved oil by double droplets in the extractant layer of the present invention;

[0042] Among them, 1. Oily wastewater inlet; 2. Extractant inlet; 3. Jet dispersion unit; 3-1. Neck section; 3-2. Throat; 3-3. Ejector; 3-4. Dispersion section; 4. Turbulent mixing unit; 5. Mixed liquid outlet; 6. Mixed liquid inlet; 7. Extractant outlet; 8. Double droplet dispersion unit; 8-1. Disc liquid distributor; 8-2. Venturi dispersion device; 8-3. Gradual convergence section; 8-4. Entrainment section; 8-5. Entrainment hole; 8-6. Gradual expansion section; 9. Interface meter; 10. Oil collecting pipe; 11. Multi-media coalescing bed; 12. Purified water outlet; 13. First control valve; 14. PLC control system; 15. Second control valve. DETAILED DESCRIPTION

[0043] The technical solutions of the present invention are described clearly and completely below with reference to specific embodiments. It should be understood that the embodiments described are only a portion of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative work are within the scope of the present invention. Unless otherwise defined, all professional and scientific terms used herein have the same meanings as those familiar to those skilled in the art.

[0044] The forward phase extraction and reverse phase extraction in the present invention are distinguished according to whether the extractant serves as the dispersed phase or the continuous phase. The forward phase extraction process refers to the extraction process in which the extractant serves as the dispersed phase and is dispersed in the continuous phase in the form of microdroplets. The reverse phase extraction process refers to the extraction process in which the extractant serves as the continuous phase and the oily wastewater serves as the dispersed phase.

[0045] The present invention fully disperses the extractant in the oily wastewater through a specific jet dispersion and turbulent mixing process, strengthens the forward phase extraction process by dispersing the extractant droplets to reduce the interfacial area, and then strengthens the reverse phase extraction process by obtaining double droplets through a double droplet dispersion process. The extraction mass transfer is strengthened by the phase interface conversion between the dispersed phase and the continuous phase, and the oil-water phase separation is achieved through a synergistic separation process to obtain purified water. Specifically, the extractant is subjected to high shear in the jet dispersion unit to form droplets of a specific particle size that are dispersed in the oily wastewater, and is subjected to a multi-stage turbulent mixing unit to strengthen droplet breakage and microextraction to form a mixed liquid. The mixed liquid is then redispersed by the double droplet dispersion unit to produce large-particle double droplets to further strengthen the extraction process of the dissolved oil, and fine extractant droplets are released through the oil-water interface. The multi-media coalescing bed layer is used to achieve efficient phase separation of droplets of this particle size.

[0046] Example 1

[0047] like Figure 1 As shown, the device for generating double droplet forward and reverse phase enhanced extraction and oil removal of the present invention comprises a forward phase dispersion extraction device and a reverse phase extraction separation device connected in sequence, wherein:

[0048] The normal phase dispersion extraction device is preferably a horizontal structure, with an oily wastewater inlet 1 at one end, a jet dispersion unit 3 and a turbulent mixing unit 4 arranged in sequence along the material flow direction, and a mixed liquid outlet 5 at the other end. The side wall of the jet dispersion unit 3 is provided with an extractant inlet 2;

[0049] The reverse-phase extraction separation device is preferably a vertical structure, with a mixed liquid inlet 6 connected to the mixed liquid outlet 5 at the top, an extractant outlet 7 and a purified water outlet 12 at the top and bottom, respectively. A double droplet dispersion unit 8 and a cooperative separation unit are sequentially arranged in the reverse-phase extraction separation device along the material flow direction. The extractant outlet 7 is connected to the extractant inlet 2 for extractant reflux to perform multi-stage extraction.

[0050] Further, combined Figure 2-3 As shown, the spray dispersion unit 3 is a plurality of units repeatedly arranged in parallel. A single spray dispersion unit 3 is a Venturi structure, comprising a necking section 3-1, a throat 3-2 and a dispersion section 3-4 connected in sequence. A plurality of ejectors 3-3 ( Figure 2 ), or a plurality of ejectors 3-3 are evenly arranged radially in the necking section 3-1 ( Figure 3), the ejector 3-3 is connected to the extractant inlet 2, the aperture of the ejector 3-3 is 0.2 to 6 mm, and can be set to multiple according to the dispersed phase flow rate, preferably 1 to 10, the tapering angle α of the necking section 3-1 of the venturi structure and the diverging angle β of the dispersion section 3-4 are 10° to 25°, the aspect ratio of the throat 3-2 is 0.5 to 2, and the injection dispersion unit 3 is used to generate micron-sized dispersed droplets. Its structural design can enhance the breakup and dispersion of the extractant and enhance the mass transfer process between droplets.

[0051] Further, combined Figure 4-5 As shown, the turbulent mixing unit 4 is a plurality of units repeatedly arranged in parallel, and a single turbulent mixing unit 4 is a cylindrical structure, including a turbulent mixing shell 4-3 and a multi-stage repeatedly arranged mixing structure arranged in the turbulent mixing shell 4-3, and each stage of the mixing structure includes a first mixing section 4-1 and two second mixing sections 4-2, and the first mixing section 4-1 and the second mixing section 4-2 are both irregular triangular prism structures, and the cross-sectional shape thereof in the horizontal axial section passing through the turbulent mixing unit 4 is an irregular triangle formed by circumscribing three equal circles with radii r1 and r2, r1 is 0.4 to 0.6 times the diameter d of the turbulent mixing unit 4, and r2 is 0.2 to 0.35 times the diameter d of the turbulent mixing unit 4; The first mixing section 4-1 and the second mixing section 4-2 are arranged in an equilateral triangle, that is, the central axes of the three mixing sections of each mixing structure are arranged in an equilateral triangle, and the horizontal sections of the first mixing section 4-1 and the two second mixing sections 4-2 are arranged in the form of apexes facing each other and bases facing each other; the axial center distance l of the two second mixing sections 4-2 in each mixing structure is 0.4 to 0.6 times the diameter d of the turbulent mixing unit 4; the dispersed mixed liquid alternately flows through the special-shaped structures of the first mixing section 4-1 and the second mixing section 4-2, and is mixed and broken alternately in multiple stages in the specific flow channel formed between the turbulent mixing shell 4-3 and each mixing structure, providing strong turbulent motion and enhancing mass transfer and dispersion between the mixed liquids.

[0052] Further, combined Figure 6As shown, the dual droplet dispersion unit 8 includes a disc-type liquid distributor 8-1 connected to the mixed liquid inlet 6. The disc-type liquid distributor 8-1 is a coil-type liquid distributor. Several Venturi dispersion devices 8-2 are installed at the outlet of the disc-type liquid distributor 8-1. The Venturi dispersion devices 8-2 include a converging section 8-3, an entrainment section 8-4, and a diverging section 8-6 along the material flow direction. The entrainment section 8-4 has multiple entrainment holes 8-5 radially defined. The diameter of the entrainment holes ranges from 1 to 5 mm, the diameter of the entrainment section 8-4 ranges from 5 to 30 mm, and the aspect ratio is 5 to 7. The converging angle of the converging section 8-3 and the diverging angle of the diverging section 8-6 range from 10° to 25°. The Venturi dispersion devices 8-2 further form dual droplets by injecting and entraining the extractant, thereby enhancing the mass transfer process.

[0053] Furthermore, combined Figure 7 As shown, the Venturi dispersion device 8-2 is evenly distributed along the circumference of the bottom of the disc liquid distributor 8-1 to improve the liquid distribution effect.

[0054] Furthermore, the collaborative separation unit includes a multi-media coalescence bed 11 and an oil collecting pipe 10 passing through the multi-media coalescence bed 11, and the distance between the multi-media coalescence bed 11 and the double droplet dispersion unit 8 is preferably set to 50 to 70 cm; the multi-media coalescence bed 11 is a medium coalescence bed filled with media of different morphologies and / or hydrophilic and hydrophobic properties, and the filled media include granular media and / or fibrous media, wherein the granular media are spherical or irregular particles with a particle size range of 0.5 to 5 mm, and the fibrous media are fiber filaments with a diameter range of 10 to 500 μm. The bed porosity of the multi-media coalescence bed 11 is 0.5 to 0.85, and the bed depth is 1000 to 2000 mm. The deep separation of small-particle extractant droplets is enhanced by medium coalescence, and they are wetted and coalesced in the medium channel and grow and float up for separation. A small amount of extractant at the bottom of the bed floats up and separates through the oil collecting pipe 10.

[0055] Furthermore, the reverse phase extraction separation device is also provided with an interface control system, which includes an interface meter 9, a PLC control system 14, and a first control valve 13 and a second control valve 15 located at the purified water outlet 12 and the extractant outlet 7, respectively. The first control valve 13 and the second control valve 15 are selected as electric stop valves; the purified water outlet 12 and the extractant outlet 7 are automatically controlled by interface-control valve linkage. The interface meter 9, the first and second control valves 13 and 15 are all connected to the PLC control system, and the interface is controlled by the control valve. The adjustment of the interface is controlled by the control valve, and is located between the dual droplet dispersion unit 8 and the collaborative separation unit to ensure the separation of the extractant and purified water in the reverse phase extraction separation device; preferably, the oil-water interface is controlled 5-15 cm above the multi-media coalescing bed 11.

[0056] The method for removing dissolved oil using the above-mentioned device for generating double droplet forward and reverse phase enhanced extraction and oil removal is specifically described as follows:

[0057] (1) The oily wastewater enters the jet dispersion unit 3 of the normal phase dispersion extraction device from the oily wastewater inlet 1, and the extractant enters the jet dispersion unit 3 from the extractant inlet 2 and is ejected through the ejector 3-3. The extractant is sheared and dispersed in the oily wastewater by the Venturi structure of the jet dispersion unit 3 to form a mixed liquid.

[0058] (2) The mixed liquid enters the turbulent mixing unit 4 and passes through the first mixing section 4-1 and the second mixing section 4-2 in each stage of the mixing structure in turn, and the micro-vortex and turbulent crushing processes are performed alternately in multiple stages to enhance the interphase transfer process of organic matter in the mixed liquid.

[0059] (3) The mixed liquid after turbulent mixing enters the double droplet dispersion unit 8 in the reverse phase extraction separation device, is evenly distributed by the disk liquid distributor 8-1, is sprayed by the venturi dispersion device 8-2, and the part of the extractant settled outside is sucked into the pipe to generate "oil-in-water-in-oil" double droplets. Figure 8 The schematic diagram of the double droplet-enhanced capture of emulsified oil and dissolved oil is shown in the figure, and further reversed-phase dispersive extraction is performed.

[0060] (4) The double droplets release the extractant droplets again after passing through the oil-water interface. Some of the extractant droplets float up and separate directly under the action of buoyancy, gravity and water drag. The unseparated small-sized extractant droplets enter the cooperative separation unit and further wet, coalesce and collide to grow on the multi-media coalescing bed 11. Some of the extractant droplets in the multi-media coalescing bed 11 float up and merge into the extractant layer for separation. Some of the extractant droplets flow to the bottom of the multi-media coalescing bed 11 and then float up through the oil collecting pipe 10 and merge into the extractant layer for separation.

[0061] (5) The purified water separated by the collaborative separation unit is discharged from the purified water outlet 12 at the bottom and enters the next process, or enters the next process after deep removal of the extractant (secondary extraction or evaporation, etc.); the extractant is discharged from the top extractant outlet 7, a part of which flows back to the extractant inlet 2, and the other part is recycled; the discharge amount of purified water and extractant is controlled by PLC to maintain the stability of the interface.

[0062] Furthermore, the extractant is selected from one or more of low-boiling-point oils and benzene series products in petroleum processing or coal chemical by-products.

[0063] Furthermore, according to the change in the content of emulsified oil and dissolved oil in the oily wastewater, the feed volume ratio of the extractant to the oily wastewater is (1-20):100.

[0064] Furthermore, in step (1), the particle size distribution of the extractant passing through the jet dispersion unit 3 is 20 to 100 μm, and the size of the dispersed particle size can be adjusted by the jet pressure and the main phase flow rate; in step (2), the particle size distribution of the extractant passing through the turbulent mixing unit 4 is 5 to 80 μm; the average flow rate in the normal phase dispersion extraction device is 0.3 to 5 m / s, that is, the average flow rate of the jet dispersion section 3 and the turbulent mixing section 4 is 0.3 to 5 m / s.

[0065] Furthermore, the water droplet particle size in the double droplets dispersed by the double droplet dispersion unit 8 in step (3) is 0.2 to 2 mm; among the extractant droplets re-released through the oil-water interface, the extractant droplets with a particle size of not less than 200 μm can directly float and separate, while the extractant droplets with a particle size of less than 200 μm enter the collaborative separation unit for deep separation; the cross-sectional flow rate in the multi-media coalescing bed 11 of the collaborative separation unit in step (4) is 0.001 to 0.03 m / s. After being processed by the collaborative separation unit, all extractant droplets with a particle size of more than 50 μm can float and separate, and the removal rate of extractant droplets with a size of more than 5 μm exceeds 99%.

[0066] Furthermore, in the extractant after oil-water separation in step (5), the ratio of reflux extractant to recovered extractant is (0.5-20):1; furthermore, the reflux extractant and the fresh extractant are mixed and injected into the extractant inlet 2, and the injection ratio of reflux extractant to fresh extractant is (0.2-20):1.

[0067] Furthermore, multiple units of a single or all modular devices can be connected in series or parallel based on the total processing capacity, dissolved oil content, floor space and other conditions to meet the requirements of processing scale and processing indicators.

[0068] Example 2

[0069] The device for generating double droplet forward and reverse phase enhanced extraction and oil removal described in Example 1 was used to treat simulated wastewater containing dissolved oil. The condensate oil byproduct was selected as the extraction agent. The main phase flow rate was 50 L / h, the extraction agent phase flow rate was 5 L / h, the emulsified oil pollutant was 600 mg / L, and the soluble oil pollutants were selected as 100 mg / L of p-xylene and thymol, and 10 mg / L of naphthalene, respectively. The extraction and separation effect of the above-mentioned device was tested.

[0070] The aperture of the injector is 0.2 mm, and the number of the injectors is set to 4 according to the dispersed phase flow rate; the necking section tapering angle α and the diffusion section diverging angle β of the injection dispersion unit are 15°, the throat length is 30 mm, and the diameter is 25 mm.

[0071] The tube diameter d of the turbulent mixing unit is 10 mm. The horizontal axial sections of the first mixing section and the second mixing section of each mixing structure are formed by three equal circles with radii r1 of 5 mm and r2 of 3 mm, respectively. They are arranged in an equilateral triangle with an axial center distance l of 5 mm.

[0072] The diameter of the entrainment section of the Venturi dispersion device is 8 mm, and two 1 mm entrainment holes are radially opened. The tapering angle of the tapering section and the gradually expanding angle of the gradually expanding section are 20°. The evenly distributed number of the Venturi dispersion devices is 24.

[0073] The multi-media coalescing bed of the collaborative separation unit is a bed of 0.5 mm particles, the bed medium is a mixture of quartz sand and polytetrafluoroethylene in a ratio of 1:1, and the bed depth is 1000 mm.

[0074] The ratio of the extractant reflux to recovery is 2:1, and the injection ratio of the reflux extractant to the fresh extractant is 1:1.

[0075] After each device has been running stably for 5 minutes, samples are taken from the inlet and outlet of the device to test the turbidity and particle size distribution of each unit as shown in the following table.

[0076] Test Location Turbidity / NTU Median particle size (um) Device import 234 5.48 Mixed liquid outlet 783 22 Purified water outlet 0.9 1.07 Extraction agent export 0.6 /

[0077] After each device had been running stably for 5 minutes, samples were taken from the mixed liquid outlet and the purified water outlet. The concentrations of the tested pollutants are shown in the table below. After mixing, only the dissolved oil content could be tested by membrane separation. The emulsified oil and the extractant could not be separated, so no data was available.

[0078]

[0079] Based on the above treatment results, the device and method described in Example 1 can be used to treat oily wastewater, achieving physical separation of emulsified oil, xylene (benzene series), naphthalene (polycyclic aromatic hydrocarbons), and thymol (phenol). Furthermore, a turbidity evaluation medium coalescing device can achieve non-dissolved phase separation. Furthermore, the water content in the extractant after separation was tested to be 0.3%, indicating a low subsequent extractant recovery load. The present invention provides a method for physically treating emulsified and dissolved oil in oily wastewater by generating a dual droplet-based forward and reverse phase enhanced extraction and oil removal device, thereby enabling the recovery and utilization of oily pollutants.

[0080] This application is described in detail for the purpose of enabling those skilled in the art to understand the contents of this application and implement them. This does not limit the scope of protection of this application. Any equivalent changes or modifications made according to the spirit of this application should be included in the scope of protection of this application.

Claims

1. A device for double droplet forward and reverse phase enhanced extraction and oil removal, characterized in that: The device comprises a normal phase dispersive extraction device and a reverse phase extraction separation device, wherein: One end of the normal phase dispersion extraction device is provided with an oily wastewater inlet, and the other end is provided with a mixed liquid outlet, and a jet dispersion unit and a turbulent mixing unit are sequentially provided inside along the material flow direction, and the side wall of the jet dispersion unit is provided with an extractant inlet; the jet dispersion unit is a plurality of units repeatedly arranged in parallel, and a single jet dispersion unit includes a necking section, a throat and a dispersion section connected in sequence, and a plurality of ejectors are evenly arranged circumferentially in the throat or radially in the necking section; the turbulent mixing unit is a plurality of units repeatedly arranged in parallel, and a single turbulent mixing unit is a cylindrical structure, including a turbulent mixing shell and a multi-stage repeatedly arranged mixing structure arranged in the turbulent mixing shell; each stage of the mixing structure of the turbulent mixing unit includes a first mixing section and two second mixing sections; the first mixing section and the second mixing section are special-shaped triangular prism structures, and the first mixing section and the second mixing section are arranged in an equilateral triangle, and the horizontal sections of the first mixing section and the two second mixing sections are arranged in the form of apexes facing each other and bases facing back to back; The upper part of the reverse-phase extraction separation device is provided with a mixed liquid inlet connected to the mixed liquid outlet, and the top and bottom are respectively provided with an extractant outlet and a purified water outlet. A double droplet dispersion unit and a collaborative separation unit are sequentially provided inside along the material flow direction, and the extractant outlet is connected to the extractant inlet; the double droplet dispersion unit includes a liquid distributor connected to the mixed liquid inlet, and a plurality of Venturi dispersion devices are provided at the outlet of the liquid distributor. The Venturi dispersion devices include a convergent section, a suction section, and a gradually expanding section in sequence along the material flow direction, and a plurality of suction holes are provided in the radial direction of the suction section; the collaborative separation unit includes a multi-media coalescing bed and an oil collecting pipe passing through the multi-media coalescing bed, and the multi-media coalescing bed is a medium coalescing bed filled with media of different morphologies or hydrophilicity and hydrophobicity.

2. The oil removal device according to claim 1, characterized in that The aperture of the injector is 0.2-6 mm, the tapering angle α of the necking section and the diverging angle β of the diffusion section are 10°-25°, and the aspect ratio of the throat is 0.5-2.

3. The oil removal device according to claim 1, characterized in that The cross-sectional shape of the first mixing section and the second mixing section in the horizontal axial section passing through the turbulent mixing unit is an irregular triangle formed by three equal circles r1 and r2 respectively, r1 is 0.4 to 0.6 times the diameter d of the turbulent mixing unit, and r2 is 0.2 to 0.35 times d; the axial center distance l of the two second mixing sections in each stage of the mixing structure is 0.4 to 0.6 times d.

4. The oil removal device according to claim 1, characterized in that The diameter of the entrainment hole is 1-5 mm, the diameter of the entrainment section is 5-30 mm, the aspect ratio is 5-7, the tapering angle of the tapering section and the dilation angle of the dilation section are 10°-25°; the Venturi dispersion devices are evenly distributed along the circumference.

5. The oil removal device according to claim 1, characterized in that: The distance between the multi-media coalescence bed and the double droplet dispersion unit is set to 50 to 70 cm; the medium filled in the multi-media coalescence bed includes granular medium and / or fibrous medium, wherein the granular medium is spherical or irregular particles with a particle size range of 0.5 to 5 mm, and the fibrous medium is fiber filaments with a diameter range of 100 to 500 µm. The bed porosity of the multi-media coalescence bed is 0.5 to 0.85, and the bed depth is 1000 to 2000 mm.

6. The oil removal device according to claim 1, characterized in that: The reverse-phase extraction separation device includes an interface control system, which includes an interface meter, a PLC control system, and control valves located at the purified water outlet and the extractant outlet, respectively. The interface meter and the control valve are both connected to the PLC control system. The purified water outlet and the extractant outlet are automatically controlled by an interface-control valve linkage. The oil-water interface is controlled to be located between the dual droplet dispersion unit and the collaborative separation unit, and is controlled to be 5-15 cm above the multi-media coalescing bed.

7. A method for producing double droplet forward and reverse phase enhanced extraction and oil removal, using the double droplet forward and reverse phase enhanced extraction and oil removal device according to any one of claims 1 to 6, characterized in that: The steps include: (1) The oily wastewater enters the jet dispersion unit, and the extractant is injected into the jet dispersion unit and dispersed in the oily wastewater through the venturi structure to form a mixed liquid; (2) The mixed liquid enters the turbulent mixing unit, where micro-swirl and turbulent fragmentation processes are performed alternately in multiple stages to enhance the interphase transfer process of organic matter in the mixed liquid; (3) The mixed liquid after turbulent mixing enters the double droplet dispersion unit, and after being evenly distributed, it is sprayed into the extractant phase through the Venturi dispersion device and the external extractant is sucked into the tube to generate double droplets for reverse phase dispersion extraction; (4) The double droplets release the extractant droplets again after passing through the oil-water interface. Some of the extractant droplets float up and separate directly, while the unseparated extractant droplets enter the cooperative separation unit and coalesce and grow in the multi-media coalescing bed. Some of the extractant droplets in the bed float up and separate, while some of the extractant droplets flow to the bottom of the bed and then float up and separate through the oil collecting pipe. (5) The purified water separated by the cooperative separation unit is discharged from the bottom purified water outlet; The extractant is discharged from the top extractant outlet, a portion of which is refluxed to the jet dispersion unit, and the other portion is recovered for treatment.

8. The oil removal method according to claim 7, characterized in that: The extractant is selected from one or more of low-boiling-point oils and benzene series products in petroleum processing or coal chemical by-products; the feed volume ratio of the extractant to the oily wastewater in step (1) is (1-20):100; the particle size distribution of the extractant passing through the jet dispersion unit is 20-100 μm; the particle size distribution of the extractant passing through the turbulent mixing unit in step (2) is 5-80 μm; and the average flow rate of the jet dispersion unit and the turbulent mixing unit is 0.3-5 m / s.

9. The oil removal method according to claim 7, characterized in that: The water droplet particle size in the double droplets dispersed by the double droplet dispersion unit in step (3) is 0.2 to 2 mm; the cross-sectional flow rate in the multi-media coalescing bed of the collaborative separation unit in step (4) is 0.001 to 0.03 m / s.

10. The oil removal method according to claim 7, characterized in that: In the extractant after oil-water separation in step (5), the ratio of reflux extractant to recovered extractant is (0.5-20):1; the reflux extractant and the fresh extractant are mixed and injected into the injection dispersion unit, and the injection ratio of reflux extractant to fresh extractant is (0.2-20):1.

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