CN112473188A - Electric field enhanced O/W emulsion demulsification and oil removal device and method - Google Patents
Electric field enhanced O/W emulsion demulsification and oil removal device and method Download PDFInfo
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Abstract
The invention discloses a device for demulsifying and deoiling O/W emulsion by electric field reinforcement, which comprises a separation cavity; an electrode assembly is arranged in the separation cavity and used for providing an electric field for forcibly transferring oil drops in the O/W emulsion, and the electrode assembly comprises a metal electrode, an upper fixed pore plate, a lower fixed pore plate, a power supply and a power-on lead, wherein the upper fixed pore plate and the lower fixed pore plate are used for fixing the metal electrode; the metal electrode is a rod-shaped electrode or a ring-shaped electrode according to different electrode shapes; the inside of the electrode component is provided with a medium coalescence element for capturing oil drops and enabling the oil drops to coalesce and grow up; and the upper ends of the inner parts of the separation cavity, which are close to the water phase outlet and the oil phase outlet, are provided with an oil-water separation component for promoting the separation of the demulsified oil phase and the demulsified water phase. The invention also discloses a demulsification and oil removal method applying the device, and the device and the method have high separation efficiency and high demulsification and oil removal depth, and are suitable for demulsification and oil removal processes of various O/W emulsions containing micro emulsified oil.
Description
Technical Field
The invention belongs to the field of oil-water separation in petrochemical industry, and particularly relates to a device and a method for demulsifying and deoiling O/W emulsion by electric field reinforcement.
Background
The petrochemical industry has complex sewage source, high petroleum content and serious emulsification, and most of oil drops exist in the sewage in an emulsified state with the particle size of about 5-20 mu m. The prior art methods for treating such wastewater include gravity settling, hydrocyclone, membrane separation, adsorption, flocculation, and air flotation. The traditional gravity settling separation method can only remove free oil drops, and has weak treatment effect on emulsified oil drops existing in an oil-in-water form; the hydrocyclone method is easy to generate secondary emulsification in the cyclone process and is not suitable for separation of emulsified oil drops; the fine separation technologies such as membrane separation, adsorption and the like are difficult to treat petrochemical industry sewage with serious emulsification due to high cost and no long-term stable operation condition; the technologies of flocculation, air flotation and the like are not suitable for occasions with large oil-containing fluctuation and have the defects of large investment, need of adding chemicals and the like. Aiming at emulsion sewage treatment in the petrochemical industry, the electric field demulsification method has wide prospect but is still in a starting stage, and the single separation technology is adopted, so that the method has different limitations.
In the prior art, the application of electric field demulsification is mostly only to arrange an electrode assembly in a separation cavity, and the demulsification process of the oil-in-water emulsion is enhanced by changing the electrode assembly or the form of an electric field. CN109384287A discloses an electrode assembly arranged in an integrated annular, rectangular and split annular rectangle, which enhances the emulsion breaking process of oil-in-water emulsion; CN208200865U discloses an electric field demulsification technology adopting a composite high-voltage pulse electric field and an alternating-current electric field to enhance the demulsification process of an oil-in-water emulsion; the disadvantage is that the emulsion breaking of oil-in-water emulsions is carried out only by means of an electric field, and the emulsion breaking under forced flow conditions cannot be achieved, or the emulsion breaking efficiency is poor. Therefore, a novel efficient demulsification method for treating the oil-in-water emulsion is developed, and has great positive significance and economic value.
Disclosure of Invention
In order to solve the defects of the prior art, the invention provides a device and a method for demulsifying and deoiling an O/W emulsion by electric field reinforcement by utilizing the forced migration effect of an electric field on oil drops and the induced coalescence effect of a medium on the oil drops.
In order to achieve the purpose, the invention adopts the following technical scheme:
an electric field enhanced O/W emulsion demulsification and oil removal device comprises a separation cavity, a liquid inlet arranged at the bottom end of the outer wall of the separation cavity, and a water phase outlet and an oil phase outlet which are arranged at the top of the outer wall of the separation cavity, wherein the oil phase outlet is positioned above the water phase outlet; an electrode assembly is arranged in the separation cavity and used for providing an electric field for forcibly transferring oil drops in the O/W emulsion, and the electrode assembly comprises a metal electrode, an upper fixed pore plate, a lower fixed pore plate, a power supply and a power-on lead, wherein the upper fixed pore plate and the lower fixed pore plate are used for fixing the metal electrode; the metal electrode is a rod-shaped electrode or a ring-shaped electrode according to different electrode shapes; the electrode assembly is uniformly filled with medium coalescence units consisting of medium particles and used for capturing oil drops in the O/W emulsion and enabling the oil drops to coalesce and grow up; and the upper ends of the inner parts of the separation cavity, which are close to the water phase outlet and the oil phase outlet, are provided with an oil-water separation component for promoting the separation of the demulsified oil phase and the demulsified water phase.
According to the preferred embodiment of the invention, the metal electrode is a rod-shaped electrode, and the metal electrode comprises a rod-shaped negative electrode and a plurality of rod-shaped positive electrodes; the metal electrode is vertically placed in the separation cavity, the negative electrode is positioned in the center of the separation cavity, and the plurality of positive electrodes are uniformly distributed around the negative electrode along the circumference; the negative electrode is used as the negative electrode of the electrode assembly and is connected with a power supply through a power-on lead, and the plurality of positive electrodes are connected in series through the power-on lead to form the positive electrode of the electrode assembly and are connected with the power supply through the power-on lead.
According to a preferred embodiment of the present invention, the rod-shaped positive electrode has a diameter of 0.03 to 0.5m and a length of 0.6 to 3 m; the diameter of the rod-shaped negative electrode is 0.03-0.5m, and the length of the rod-shaped negative electrode is 0.8-3.2 m; the fixed pore plate comprises an upper fixed pore plate and a lower fixed pore plate which are made of polytetrafluoroethylene, the diameter of the fixed pore plate is 0.5-2.8m, the thickness of the fixed pore plate is 0.02-0.8m, the fixed pore plate is provided with an opening, two ends of the cathode electrode and two ends of the anode electrode respectively penetrate into the openings, so that the fixed pore plate is fixed by the upper fixed pore plate and the lower fixed pore plate, the diameter of the opening at the center of the fixed pore plate is 0.05-0.52m and used for placing the cathode electrode, and the diameter of the opening at the outer ring is 0.05-0.52m and used for placing the anode electrode; a small hole with the diameter of 0.02m is arranged at a position 0.05-0.2m below the top end of the positive electrode and is used for connecting an electrified lead to realize the connection of the positive electrode of the electrode assembly.
According to the preferred embodiment of the invention, the metal electrode is an annular electrode, the metal electrode comprises a cylindrical metal electrode positioned at the center of the separation cavity and an annular cylindrical metal electrode tightly attached to the inner wall of the separation cavity, any one of the cylindrical metal electrode and the annular cylindrical metal electrode is a positive electrode, the other metal electrode is a negative electrode, and the positive electrode and the negative electrode are respectively connected with a power supply through electrified leads.
According to a preferred embodiment of the present invention, the metal electrode having a ring-cylindrical shape has an inner diameter of 0.5 to 2.8m, an outer diameter of 0.8 to 3.2m, a thickness of 0.1 to 0.5m, and a length of 0.6 to 3.6 m; the diameter of the cylindrical metal electrode is 0.05-0.3m, and the length of the cylindrical metal electrode is 0.6-3.6 m; the fixed pore plate comprises an upper fixed pore plate and a lower fixed pore plate which are made of polytetrafluoroethylene, the diameter of the fixed pore plate is 0.45-2.75m, the thickness of the fixed pore plate is 0.02-0.2m, the center of the fixed pore plate is provided with an opening, the cylindrical metal electrode penetrates through the opening so as to fix the cylindrical metal electrode, the fixed pore plate is provided with a circular opening, and the circular cylindrical metal electrode penetrates through the opening so as to fix the circular cylindrical metal electrode; the diameter of an opening at the center of the fixed orifice plate is 0.1-0.35m, the inner diameter of the circular opening is 0.55-2.85m, the outer diameter is 0.85-3.25m, and the width of the opening is 0.15-0.55 m.
According to a preferred embodiment of the invention, the media particles constituting the media coalescing unit are one or more oleophilic or a combination of oleophilic and oleophobic media particles, the media particles being spherical or shaped particles of size 0.1-5 mm; the medium particles can be arranged in layers according to different sizes to form different types of medium beds.
According to the preferred embodiment of the invention, the lower fixed orifice plate is positioned at the bottom of the inner side of the separation cavity, and the distance between the upper fixed orifice plate and the lower fixed orifice plate is 80% of the height of the separation cavity, so that the interval from the bottom to 80% of the height of the separation cavity is an electric field and medium coalescence cooperative demulsification interval, and the interval from 80% of the height to the top is an oil-receiving water separation interval; the distance between the oil-water separation component and the top of the separation cavity is 5% -15% of the height of the separation cavity.
The invention also discloses a method for strengthening O/W emulsion demulsification and deoiling by applying the electric field of the device, which comprises the following steps:
(1) the O/W emulsion enters the separation cavity through the liquid inlet, under the action of an electric field, oil drops generate rapid directional movement between the electrode assemblies, and the stability of an oil drop interface is weakened.
(2) Oil drops moving directionally under the action of an electric field are captured and induced to coalesce by the medium coalescing unit filled between the electrodes, small oil drops grow into large oil drops on the surface of the medium, and the oil drops are gathered in the medium layer and separated under the action of fluid drag force and buoyancy.
(3) After the mixed liquid subjected to the synergistic and reinforced separation of the electric field and the medium coalescence unit passes through the oil-water separation component, the oil phase is enriched at the upper part of the separation cavity and is recovered through the oil phase outlet, and the purified water is discharged out of the cavity through the water phase outlet.
According to a preferred embodiment of the invention, the electric field pattern is a direct current electric field, a pulsed electric field or an alternating current electric field; when the direct current electric field is adopted, the voltage is 10-2000V; when the pulse electric field is adopted, the voltage is 10-2000V, the frequency is 5-3000Hz, the duty ratio is 0.1-0.9, and the ratio of the positive and negative electrification time is 0-1; when the alternating current electric field is adopted, the voltage is 10-2000V, and the frequency is 5-3000 Hz.
According to a preferred embodiment of the invention, the cross-sectional flow rate of the O/W emulsion through the separation chamber is between 0.001m/s and 0.2m/s and the pressure drop of the device is between 0.005 and 0.6 MPa.
The invention has the beneficial effects that: the demulsification process of the oil-in-water emulsion is strengthened by combining the forced migration effect of an electric field on oil drops and the induced coalescence effect of a medium on the oil drops. The device and the method for demulsifying and deoiling the O/W emulsion by electric field reinforcement have high separation efficiency and high demulsification and deoiling depth, and are suitable for the demulsification and deoiling process of various O/W emulsions containing micro emulsified oil.
Drawings
FIG. 1 is a schematic structural diagram of a device for demulsifying and deoiling by coalescence of rod-shaped electrodes and media, which is related by the invention;
FIG. 2 is a top view of a rod-shaped electrode and a medium coalescing cooperating unit structure according to the present invention;
FIG. 3 is a schematic diagram of a structure of a ring-shaped electrode and a medium coalescence cooperative unit related to the invention;
description of the symbols:
1-liquid inlet, 2-water phase outlet, 3-oil phase outlet, 4-oil-water separation component, 5-separation cavity, 6-medium coalescence unit, 7-fixed orifice plate, 8-positive electrode, 9-negative electrode, 10-power supply, 11-electrified lead.
Detailed Description
The invention is further illustrated with reference to the following figures and examples. It should be noted that the following examples are only for illustrating the present invention and should not be construed as limiting the scope of the present invention, and that the insubstantial modifications and adaptations of the invention by those skilled in the art based on the teachings herein are within the scope of the present invention.
The technical conception of the invention is as follows: the demulsification and separation of emulsified oil drops are carried out by utilizing the forced migration effect of an electric field on the oil drops and the induced coalescence effect of a medium on the oil drops. The forced migration action of the electric field on the oil droplets refers to the migration of the oil droplets under the action of electrohydrodynamics, that is, under the action of the electric field, the oil droplets generally move directionally in the direction of increasing the gradient of the electric field, and generally dielectrophoresis is mostly used. The induced coalescence of the oil droplets by the medium refers to the wetting coalescence that the oleophilic medium has on the oil droplets so that the oil droplets in the O/W emulsion can be captured by the medium and induce coalescence. And coupling the two functions to realize deep demulsification and oil removal of the O/W emulsion.
Example 1
As shown in fig. 1, the device for demulsifying and deoiling an O/W emulsion by electric field enhancement comprises a separation cavity 5, a liquid inlet 1 arranged at the bottom end of the outer wall of the separation cavity 5, and a water phase outlet 2 and an oil phase outlet 3 arranged at the top of the outer wall of the separation cavity 5, wherein the oil phase outlet 3 is positioned above the water phase outlet 2; an electrode assembly is arranged in the separation cavity 5 and used for providing an electric field for forcibly transferring oil drops in the O/W emulsion, and the electrode assembly comprises a metal electrode, a fixed pore plate 7 for fixing the metal electrode, a power supply 10 and an electrified lead 11; the electrode assembly is uniformly filled with medium coalescence units 6 consisting of medium particles and used for capturing oil drops in the O/W emulsion and enabling the oil drops to coalesce and grow; the upper ends of the inner parts of the separation cavity 5, which are close to the water phase outlet 2 and the oil phase outlet 3, are provided with an oil-water separation component 4 for promoting the separation of the demulsified oil phase and the demulsified water phase.
Further, the metal electrode is different according to the shape of the electrode, and the metal electrode is a rod-shaped electrode or a ring-shaped electrode.
Further, the fixed orifice plate 7 comprises an upper fixed orifice plate and a lower fixed orifice plate which are made of polytetrafluoroethylene, and the metal electrode is fixed by the upper fixed orifice plate 7 and the lower fixed orifice plate 7.
Further, when the metal electrode is a rod-shaped electrode, the metal electrode comprises a rod-shaped negative electrode 9 and a plurality of rod-shaped positive electrodes 8. The negative electrode 9 and the positive electrode 8 are vertically placed in the separation cavity 5, as shown in fig. 2, the negative electrode 9 is located in the center of the separation cavity 5, and the plurality of positive electrodes 8 are uniformly distributed around the negative electrode 9 along the circumference. The negative electrode 9 is used as the negative electrode of the electrode assembly and is connected with a power supply 10 through a power-on lead 11, and the plurality of positive electrodes 8 are connected in series through the power-on lead 11 to form the positive electrode of the electrode assembly and are connected with the power supply 10 through the power-on lead 11.
Preferably, the rod-shaped positive electrode 8 has a diameter of 0.03 to 0.5m and a length of 0.6 to 3 m; the diameter of the rod-shaped negative electrode 9 is 0.03-0.5m, and the length is 0.8-3.2 m; the diameter of the fixed orifice plate 7 is 0.5-2.8m, the thickness is 0.02-0.8m, the fixed orifice plate 7 is provided with an opening, two ends of the negative electrode 9 and the positive electrode 8 respectively penetrate into the opening so as to be fixed by the upper and lower fixed orifice plates 7, the diameter of the opening at the center of the fixed orifice plate 7 is 0.05-0.52m and used for placing the negative electrode 9, and the diameter of the opening at the outer ring is 0.05-0.52m and used for placing the positive electrode 8; a small hole with the diameter of 0.02m is arranged at the position 0.05-0.2m below the top end of the positive electrode 8 and is used for connecting an electrified lead 11 to realize the connection of the positive electrode of the electrode assembly.
Further, as shown in fig. 3, when the metal electrode is an annular electrode, the metal electrode includes a cylindrical metal electrode located at the center of the separation cavity 5 and an annular cylindrical metal electrode tightly attached to the inner wall of the separation cavity 5, the cylindrical metal electrode is a positive electrode 8, the annular cylindrical metal electrode is a negative electrode 9, or the positive and negative electrodes are convertible, that is, the cylindrical metal electrode is the negative electrode 9, and the annular cylindrical metal electrode is the positive electrode 8; the positive electrode 8 and the negative electrode 9 are respectively connected with a power supply 10 through electrified leads 11.
Preferably, the inner diameter of the annular columnar metal electrode is 0.5-2.8m, the outer diameter is 0.8-3.2m, the thickness is 0.1-0.5m, and the length is 0.6-3.6 m; the diameter of the cylindrical metal electrode is 0.05-0.3m, and the length of the cylindrical metal electrode is 0.6-3.6 m; the diameter of the fixed orifice plate 7 is 0.45-2.75m, the thickness is 0.02-0.2m, an opening is arranged at the center of the fixed orifice plate 7, the cylindrical metal electrode penetrates through the opening to fix the cylindrical metal electrode, a circular opening is arranged on the fixed orifice plate 7, and the circular cylindrical metal electrode penetrates through the opening to fix the circular cylindrical metal electrode; the diameter of an opening at the center of the fixed orifice plate 7 is 0.1-0.35m, the inner diameter of the circular opening is 0.55-2.85m, the outer diameter is 0.85-3.25m, and the opening width is 0.15-0.55 m; preferably, the two fixed orifice plates 7 are respectively fixed at positions 0.1m away from the upper and lower ends of the annular columnar metal electrode.
Further, the media particles that make up the media coalescing element 6 are one or more media particles that are oleophilic or a combination of oleophilic and oleophobic. Preferably, the media particles are spherical or shaped particles having a size of 0.1 to 5 mm.
Further, the medium particles can be arranged in layers according to different sizes to form different types of medium beds.
Further, the media coalescing unit 6 may be modular for ease of removal, replacement, and cleaning.
Further, the lower fixed orifice plate 7 is located at the bottom of the inner side of the separation cavity 5, and the distance between the upper fixed orifice plate 7 and the lower fixed orifice plate 7 is 80% of the height of the separation cavity 5, so that the interval from the bottom to 80% of the height of the separation cavity 5 is an electric field and medium coalescence cooperative demulsification interval, and the interval from 80% of the height to the top is an oil-receiving water separation interval.
Further, the distance between the oil-water separation component 4 and the top of the separation cavity 5 is 5% -15% of the height of the separation cavity 5.
The method for demulsifying and deoiling the O/W emulsion by using the device comprises the following steps:
(1) the O/W emulsion enters the separation cavity 5 through the liquid inlet 1, under the action of an electric field, oil drops generate rapid directional movement between the electrode assemblies, and the stability of an oil drop interface is weakened.
(2) Oil drops moving directionally under the action of an electric field are captured and induced to coalesce by the medium coalescing unit 6 filled between the electrodes, small oil drops grow into large oil drops on the surface of the medium, and the oil drops are gathered in the medium layer and separated under the action of fluid drag force and buoyancy.
(3) After the mixed liquid subjected to the synergistic and reinforced separation of the electric field and the medium coalescence unit passes through the oil-water separation component 4, the oil phase is enriched at the upper part of the separation cavity 5 and is recovered through the oil phase outlet 3, and the purified water is discharged out of the cavity through the water phase outlet 2.
Further, the electric field type is a direct current electric field, a pulse electric field or an alternating current electric field. When the direct current electric field is adopted, the voltage is 10-2000V; when the pulse electric field is adopted, the voltage is 10-2000V, the frequency is 5-3000Hz, the duty ratio is 0.1-0.9, and the ratio of the positive and negative electrification time is 0-1; when the alternating current electric field is adopted, the voltage is 10-2000V, and the frequency is 5-3000 Hz.
Furthermore, the cross-sectional flow rate of the O/W emulsion passing through the separation cavity is 0.001-0.2 m/s, and the pressure drop of the device is 0.005-0.6 MPa.
Example 2
A certain amount of fresh water is required to be injected into an atmospheric pressure reduction device of a petrochemical plant, salt in crude oil is fully dissolved in water to form an emulsion of petroleum and water, oil-water separation treatment is carried out after fractionation, oily wastewater is obtained, and due to fluctuation of working conditions, the oily content in the oily wastewater obtained after dehydration treatment is too high, so that downstream treatment is greatly influenced. The oily wastewater is treated by adopting the device and the method for demulsifying and deoiling the dielectric synergetic O/W emulsion, wherein the electrode assembly of the embodiment 1 is a rod electrode.
The method comprises the following steps:
(1) oily waste water discharged by an atmospheric and vacuum distillation device enters a separation cavity through a liquid inlet, the content of undissolved oil in the oily waste water is 3000mg/L, the particle size of oil drops is 0.01-50 mu m, the oil drops generate rapid directional movement under the action of an electric field, and the stability of an oil drop interface is weakened. After the process, the content of the undissolved oil in the oily wastewater is reduced to 1000mg/L, and the grain diameter of oil drops is increased to 300 mu m.
(2) Oil drops moving directionally under the action of an electric field are captured and induced to coalesce by the medium coalescing unit filled between the electrodes, small oil drops grow into large oil drops on the surface of the medium, the oil drops are gathered in the medium layer, and finally the oil drops are separated under the action of fluid drag force and buoyancy.
(3) After the mixed liquid subjected to the synergistic and reinforced separation of the electric field and the medium coalescence unit passes through the oil-water separation component, the oil phase is enriched at the upper part of the separation cavity and is recovered through the oil phase outlet, the purified water is discharged out of the cavity through the water phase outlet, and the content of the oil in a non-dissolved state in the purified water can be reduced to 5 mg/L.
And (4) analyzing results: the content of the undissolved oil in the oily wastewater before treatment is 3000mg/L, and the content of the undissolved oil in the purified water after treatment is 5mg/L, so that the oil-water separation index of the oily wastewater is met.
Example 3
In a sewage treatment plant of a petrochemical enterprise, wastewater discharged from a buffer tank is treated by adopting the device and the method for demulsifying and deoiling an O/W emulsion by using the electrode assembly of the embodiment 1 as a rod electrode in cooperation with electrolysis.
The method comprises the following steps:
(1) oily waste water discharged from the buffer pool enters the separation cavity through the liquid inlet, the content of undissolved oil in the oily waste water is 500mg/L, the particle size of oil drops is 0.1-30 mu m, the oil drops generate rapid directional movement under the action of an electric field, and the stability of an oil drop interface is weakened. After the process, the content of the undissolved oil in the oily wastewater is reduced to 300mg/L, and the grain diameter of oil drops is increased to 200 mu m.
(2) Oil drops moving directionally under the action of an electric field are captured and induced to coalesce by the medium coalescing unit filled between the electrodes, small oil drops grow into large oil drops on the surface of the medium, the oil drops are gathered in the medium layer, and finally the oil drops are separated under the action of fluid drag force and buoyancy.
(3) After the mixed liquid subjected to the synergistic and reinforced separation of the electric field and the medium coalescence unit passes through the oil-water separation component, the oil phase is enriched at the upper part of the separation cavity and is recovered through the oil phase outlet, the purified water is discharged out of the cavity through the water phase outlet, and the content of the oil in a non-dissolved state in the purified water can be reduced to 5 mg/L.
And (4) analyzing results: the content of the undissolved oil in the oily wastewater before treatment is 500mg/L, and the content of the undissolved oil in the purified water after treatment is 5mg/L, which meets the regulations of wastewater recycling engineering design standards on oil content discharge.
Example 4
The oil-in-water emulsion is treated by adopting the dielectric synergistic O/W emulsion demulsification and deoiling device and method with the electrode assembly of the example 1 being a ring electrode. The central cylindrical electrode of the electrode assembly in the device is a negative electrode, and the annular cylindrical electrode is a positive electrode; the diameter of the cylindrical negative electrode is 0.3m, and the length of the cylindrical negative electrode is 1 m; the inner diameter of the annular cylindrical positive electrode was 1.4m, the outer diameter was 1.6m, the thickness was 0.2m, and the length was 1 m.
The method comprises the following steps:
(1) 300mL of oil-in-water emulsion with the content of undissolved oil of 1000mg/L is introduced into the separation cavity through the liquid inlet, the grain diameter of oil drops is 1-100 mu m, under the action of an electric field, the oil drops generate rapid directional movement, and the interface stability of the oil drops is weakened.
(2) Oil drops moving directionally under the action of an electric field are captured and induced to coalesce by the medium coalescing unit filled between the electrodes, small oil drops grow into large oil drops on the surface of the medium, the oil drops are gathered in the medium layer, and finally the oil drops are separated under the action of fluid drag force and buoyancy.
(3) After the mixed liquid subjected to the synergistic and reinforced separation of the electric field and the medium coalescence unit passes through the oil-water separation component, the oil phase is enriched at the upper part of the separation cavity and is recovered through the oil phase outlet, the purified water is discharged out of the cavity through the water phase outlet, and the content of the oil in a non-dissolved state in the purified water can be reduced to 10 mg/L.
And (4) analyzing results: the content of the undissolved oil in the oil-in-water emulsion before treatment is 1000mg/L, and the content of the undissolved oil in the purified water after treatment is 10mg/L, so that the oil-water separation index of the oil-containing emulsion is met.
Claims (10)
1. The device for demulsifying and deoiling the O/W emulsion enhanced by the electric field is characterized by comprising a separation cavity, a liquid inlet, a water phase outlet and an oil phase outlet, wherein the liquid inlet is formed in the bottom end of the outer wall of the separation cavity, the water phase outlet and the oil phase outlet are formed in the top of the outer wall of the separation cavity, and the oil phase outlet is positioned above the water phase outlet; an electrode assembly is arranged in the separation cavity and used for providing an electric field for forcibly transferring oil drops in the O/W emulsion, and the electrode assembly comprises a metal electrode, an upper fixed pore plate, a lower fixed pore plate, a power supply and a power-on lead, wherein the upper fixed pore plate and the lower fixed pore plate are used for fixing the metal electrode; the metal electrode is a rod-shaped electrode or a ring-shaped electrode according to different electrode shapes; the electrode assembly is uniformly filled with medium coalescence units consisting of medium particles and used for capturing oil drops in the O/W emulsion and enabling the oil drops to coalesce and grow up; and the upper ends of the inner parts of the separation cavity, which are close to the water phase outlet and the oil phase outlet, are provided with an oil-water separation component for promoting the separation of the demulsified oil phase and the demulsified water phase.
2. The apparatus for demulsifying and deoiling as claimed in claim 1, wherein the metal electrode is a rod-like electrode, and the metal electrode comprises a rod-like negative electrode and a plurality of rod-like positive electrodes; the metal electrode is vertically placed in the separation cavity, the negative electrode is positioned in the center of the separation cavity, and the plurality of positive electrodes are uniformly distributed around the negative electrode along the circumference; the negative electrode is used as the negative electrode of the electrode assembly and is connected with a power supply through a power-on lead, and the plurality of positive electrodes are connected in series through the power-on lead to form the positive electrode of the electrode assembly and are connected with the power supply through the power-on lead.
3. The apparatus for demulsifying and deoiling as claimed in claim 2, wherein the diameter of the positive electrode is 0.03-0.5m, and the length is 0.6-3 m; the diameter of the negative electrode is 0.03-0.5m, and the length of the negative electrode is 0.8-3.2 m; the fixed pore plate comprises an upper fixed pore plate and a lower fixed pore plate which are made of polytetrafluoroethylene, the diameter of the fixed pore plate is 0.5-2.8m, the thickness of the fixed pore plate is 0.02-0.8m, the fixed pore plate is provided with an opening, two ends of the cathode electrode and two ends of the anode electrode respectively penetrate into the openings, so that the fixed pore plate is fixed by the upper fixed pore plate and the lower fixed pore plate, the diameter of the opening at the center of the fixed pore plate is 0.05-0.52m and used for placing the cathode electrode, and the diameter of the opening at the outer ring is 0.05-0.52m and used for placing the anode electrode; a small hole with the diameter of 0.02m is arranged at a position 0.05-0.2m below the top end of the positive electrode and is used for connecting an electrified lead to realize the connection of the positive electrode of the electrode assembly.
4. The demulsification and oil removal device as claimed in claim 1, wherein the metal electrode is an annular electrode, the metal electrode comprises a cylindrical metal electrode positioned at the center of the separation chamber and an annular metal electrode tightly attached to the inner wall of the separation chamber, any one of the cylindrical metal electrode and the annular metal electrode is a positive electrode, the other metal electrode is a negative electrode, and the positive electrode and the negative electrode are respectively connected with a power supply through conducting wires.
5. The apparatus for demulsifying and removing oil of claim 4 wherein the metal electrode in the shape of a cylinder has an inner diameter of 0.5-2.8m, an outer diameter of 0.8-3.2m, a thickness of 0.1-0.5m and a length of 0.6-3.6 m; the diameter of the cylindrical metal electrode is 0.05-0.3m, and the length of the cylindrical metal electrode is 0.6-3.6 m; the fixed pore plate comprises an upper fixed pore plate and a lower fixed pore plate which are made of polytetrafluoroethylene, the diameter of the fixed pore plate is 0.45-2.75m, the thickness of the fixed pore plate is 0.02-0.2m, the center of the fixed pore plate is provided with an opening, the cylindrical metal electrode penetrates through the opening so as to fix the cylindrical metal electrode, the fixed pore plate is provided with a circular opening, and the circular cylindrical metal electrode penetrates through the opening so as to fix the circular cylindrical metal electrode; the diameter of an opening at the center of the fixed orifice plate is 0.1-0.35m, the inner diameter of the circular opening is 0.55-2.85m, the outer diameter is 0.85-3.25m, and the width of the opening is 0.15-0.55 m.
6. The apparatus for demulsifying and deoiling as claimed in claim 1, wherein the media particles composing the media coalescing unit are one or more media particles with lipophilicity or combination of lipophilicity and lipophobicity, and the media particles are spherical or shaped particles with size of 0.1-5 mm; the medium particles can be arranged in layers according to different sizes to form different types of medium beds.
7. The demulsification and oil removal device as claimed in claim 1, wherein the lower fixed orifice plate is positioned at the bottom of the inner side of the separation cavity, and the distance between the upper fixed orifice plate and the lower fixed orifice plate is 80% of the height of the separation cavity, so that the interval from the bottom to 80% of the height of the separation cavity is an electric field and medium coalescence cooperative demulsification interval, and the interval from 80% of the height to the top is an oil and water receiving and separating interval; the distance between the oil-water separation component and the top of the separation cavity is 5% -15% of the height of the separation cavity.
8. A method for demulsifying and deoiling an O/W emulsion by applying the electric field enhanced O/W emulsion of any one of the devices of claims 1-7, wherein the method comprises the steps of:
(1) the O/W emulsion enters the separation cavity through the liquid inlet, under the action of an electric field, oil drops generate rapid directional movement between the electrode assemblies, and the stability of an oil drop interface is weakened;
(2) oil drops moving directionally under the action of an electric field are captured and induced to coalesce by a medium coalescing unit filled between electrodes, small oil drops grow into large oil drops on the surface of a medium, and the oil drops are gathered in a medium layer and separated under the action of fluid drag force and buoyancy;
(3) after the mixed liquid subjected to the synergistic and reinforced separation of the electric field and the medium coalescence unit passes through the oil-water separation component, the oil phase is enriched at the upper part of the separation cavity and is recovered through the oil phase outlet, and the purified water is discharged out of the cavity through the water phase outlet.
9. The method for demulsifying and removing oil of claim 8 wherein the electric field is in the form of a dc electric field, a pulsed electric field or an ac electric field; when the direct current electric field is adopted, the voltage is 10-2000V; when the pulse electric field is adopted, the voltage is 10-2000V, the frequency is 5-3000Hz, the duty ratio is 0.1-0.9, and the ratio of the positive and negative electrification time is 0-1; when the alternating current electric field is adopted, the voltage is 10-2000V, and the frequency is 5-3000 Hz.
10. The method of claim 8, wherein the cross-sectional flow rate of the O/W emulsion through the separation chamber is 0.001-0.2 m/s, and the pressure drop of the apparatus is 0.005-0.6 MPa.
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| CN113307337A (en) * | 2021-06-18 | 2021-08-27 | 重庆工商大学 | Oil-in-water emulsion breaking and separating device for electric field coupling conductive particle bed layer |
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| CN115228145A (en) * | 2022-09-21 | 2022-10-25 | 北京石油化工学院 | Crude oil vertical settling dehydration tank and oil-water separation method thereof |
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