A device for treating oilfield produced water by coupling electrocoagulation and reverse osmosis

Abstract

The utility model relates to water treatment equipment technical field especially is involved in a kind of electrochemical coalescence coupling oilfield produced water treatment device of reverse electrode, including jar body, the two side walls of jar body are respectively set export and entrance, coalescence plate assembly, electrode plate assembly and electrode cleaning mechanism are sequentially set in jar body inner chamber along water flow direction;Electrode cleaning mechanism is washed to electrode plate assembly, electrode plate assembly includes several vertical interlaced setting anode plate and cathode plate, anode plate and cathode plate top end are respectively set terminal pin, terminal pin extends out jar body and is connected with control cabinet wiring end by wire, control cabinet controls anode plate and cathode plate polarity periodicity exchange, realizes reverse electrode operation, the device realizes the corrosion inhibition, scale inhibition, sterilization and water quality purification stability of oilfield produced water, self-cleaning electrode scaling, ensure long-term operation of electrode and zero addition of chemical agent, greatly reduce processing cost and maintenance intensity.

Description

Technical Field

[0001] This utility model relates to the field of water treatment equipment technology, and in particular to a reversible electrochemical coalescence coupled oilfield produced water treatment device. Background Technology

[0002] Oilfield produced water is oily wastewater produced along with crude oil during the crude oil extraction process and after separation by a separator. It typically contains crude oil, suspended solids, corrosive media (such as CO2 and H2S), ferrous ions (Fe²⁺), and sulfate-reducing bacteria (SRB), and is characterized by high mineralization, strong corrosiveness, and easy scaling.

[0003] Currently, conventional treatment employs a three-stage process of "buffer oil removal—coagulation sedimentation—pressure filtration," but this process suffers from low post-treatment water quality compliance and instability. Despite the addition of large quantities of "three-proof" agents (corrosion inhibitors, bactericides, and scale inhibitors) in actual operation, the limited mechanisms of action of these agents and the ease with which metal surfaces are covered by oil and sludge result in poor agent effectiveness, with corrosion and scaling problems remaining prominent. To fundamentally address these issues, research has been conducted on the application of electrochemical pre-oxidation technology for treating oilfield produced water. This technology generates strong oxidizing substances through electrochemical reactions, effectively removing corrosive components and pollutants from the water, offering advantages such as reduced chemical agent usage, lower operating costs, and improved water quality stability. However, current electrochemical technology still faces some technical bottlenecks in oilfield applications, such as short electrode lifespan, easy sulfur deposition at the anode, easy scaling at the cathode, and the impact of crude oil contamination on electrode conductivity.

[0004] Therefore, this application provides a reversible electrochemical coalescence coupled oilfield produced water treatment device to solve the problems mentioned in the background art. Utility Model Content

[0005] The purpose of this invention is to provide a reversible electrochemical coalescence coupling oilfield produced water treatment device, which solves problems such as low compliance rate of existing oilfield produced water, unstable water quality, short electrode life, easy sulfur formation on the anode, easy scaling on the cathode, and crude oil contamination affecting the conductivity of the electrodes.

[0006] To solve the above-mentioned technical problems, this utility model provides a reversible electrochemical coalescence coupling oilfield produced water treatment device, including a tank body. Outlets and inlets are respectively provided on the two side walls of the tank body. A coalescence plate assembly, an electrode plate assembly, and an electrode cleaning mechanism are sequentially arranged along the water flow direction within the tank body. The electrode cleaning mechanism cleans the electrode plate assembly. The electrode plate assembly includes several vertically staggered anode plates and cathode plates. Terminals are respectively provided at the top of the anode and cathode plates. The terminals extend out of the tank body and are connected to the terminals of a control cabinet via wires. The control cabinet controls the periodic reversal of the polarity of the anode and cathode plates to achieve reversible operation.

[0007] A further improvement of the present invention is that: the coalescing plate assembly includes a ring body, the two side walls of the ring body are adapted to fit the inner wall of the tank body, gaps are provided between the top and bottom of the ring body and the tank body, and a number of vertically arranged coalescing corrugated plates are evenly arranged on the inner wall of the ring body. The direction of the grooves in the coalescing corrugated plates is at a 45° angle to the horizontal plane, and the direction of the grooves in adjacent coalescing corrugated plates is at a 90° angle to each other. The coalescing corrugated plates are made of fiberglass.

[0008] A further improvement of this utility model is that an oil outlet and a sludge outlet are respectively provided at the top and bottom of the outer wall of the tank body. The oil outlet and the sludge outlet are located between the coalescing plate assembly and the electrode plate assembly. An oil baffle and a sludge baffle are respectively provided on the rear side of the oil outlet and the sludge outlet. The oil baffle and the sludge baffle are fixed to the inner wall of the tank body.

[0009] A further improvement of the present invention is that the electrode plate assembly includes an annular component, and two tubes are provided on the top surface of the annular component. Both the annular component and the tubes are made of polytetrafluoroethylene, and the annular component is tightly fitted into the inner wall of the tank.

[0010] A further improvement of this utility model is that: several anode plates and cathode plates are vertically and parallelly arranged on the inner wall of the annular component, the anode plates and cathode plates are adaptable to reversal, corrosion resistant, and have a long service life. Anode support plates are provided on one side of the top surface of several anode plates, and the top of several anode support plates is connected to the bottom surface of the anode conductive plate. A cathode support plate is provided on one side of the top surface of several cathode plates, and the top of several cathode support plates is connected to the bottom surface of the cathode conductive plate. There is a gap between the anode conductive plate and the cathode conductive plate.

[0011] A further improvement of this utility model is that: terminals are provided on the top surfaces of both the anode conductive plate and the cathode conductive plate, and the terminals pass through the pipe body and are connected to the control cabinet via cables. The control cabinet is located on one side of the tank body. The power supply for the anode conductive plate and the cathode conductive plate in the control cabinet is a DC power supply system with an input voltage of 220 volts and an output voltage of 0~20 volts. The current and voltage are adjustable. The output terminals of the power supply are respectively connected to the terminals on the top surfaces of the anode conductive plate and the cathode conductive plate via wires.

[0012] A further improvement of this utility model lies in that: the electrode plate assembly further includes two arc-shaped fixing strips, which are correspondingly disposed on the lower sides of the anode plate and cathode plate. Multiple fixing blocks are evenly arranged on the inner sidewalls of the arc-shaped fixing strips, with adjacent fixing blocks forming a group of two. The two fixing blocks in each group are spaced apart to form an insertion port, which is adapted to fit the bottom sidewalls of the anode plate and cathode plate. Through-bolts are respectively provided at both ends of the two arc-shaped fixing strips, and the ends of the bolts are fixed by nuts. Both the arc-shaped fixing strips and the fixing blocks are made of insulating material.

[0013] A further improvement of the present invention is that the electrode cleaning mechanism includes a motor, which is fixed on the outside of the side wall of the tank where the outlet is located. The side wall of the tank is also provided with an installation end tube, and a sealed bearing is provided inside the installation end tube. The output shaft of the motor is fitted into the inner ring of the sealed bearing and extends into the inner cavity of the tank. A threaded rod is provided at the end of the motor output shaft, and the threaded rod is screwed into the threaded hole in the middle of the slider.

[0014] A further improvement of this utility model is that: a horizontal sliding plate is provided on the bottom surface of the slider, and at least one guide block is provided on the top surface of the sliding plate on both sides of the slider. A guide groove is provided on the top surface of the guide block, and a slide rail provided on the bottom surface of the bracket is slidably nested in the guide groove. One end of the bracket is fixed to the inner side of the tank side wall, and the other end of the bracket is rotatably connected to the end of the threaded rod.

[0015] A further improvement of this utility model is that: an arc-shaped mounting plate is fixedly connected to the bottom surface of the slide plate, and multiple rows of horizontal pipes are evenly arranged on the bottom surface of the mounting plate. Each horizontal pipe is vertically connected to multiple vertical water spray pipes. Several water spray holes are evenly opened on the pipe wall of each water spray pipe. The ends of the horizontal pipes converge and connect to the main pipe. The main pipe is connected to the water supply pipe. The water supply pipe passes through the side wall of the tank and is connected to the external high-voltage electrode cleaning fluid. The motor drives the water spray pipe to move horizontally to the gap between the anode plate and the cathode plate for rinsing.

[0016] By adopting the above technical solution, this utility model has the following beneficial effects:

[0017] 1. This utility model provides a reversible electrochemical coalescence coupling oilfield produced water treatment device. This device effectively promotes oil droplet coalescence in the produced water through the fiberglass coalescence corrugated plate in the coalescence plate assembly, improving oil-water separation efficiency and preventing oil adhesion to the electrodes. The electrode plate assembly generates strong oxidizing substances through electrochemical reactions, killing SRB (sulfuric acid oxidant) without the addition of chemical agents, removing corrosive, scaling components, and harmful substances such as Fe²⁺ ions, stabilizing the water quality, and further removing corrosive components and pollutants from the water. This synergistic effect improves treatment efficiency, ensuring reduced corrosivity and stable water quality compliance in the treated produced water. It solves the problems of unstable water quality and low compliance rate in traditional processes. Furthermore, the control cabinet controls the periodic reversal of the anode and cathode, actively reversing the electrode reaction direction, effectively preventing problems such as anode sulfur deposition, cathode scaling, and crude oil contamination of the electrodes, extending electrode lifespan, and reducing equipment operating costs.

[0018] 2. The present invention provides a reversible electrochemical coalescence coupled oilfield produced water treatment device. The electrode cleaning mechanism of the device is driven by a motor to move the water spray pipe horizontally to automatically rinse the anode plate and cathode plate, avoiding the tedious operation of manual cleaning and reducing maintenance workload and labor costs. Attached Figure Description

[0019] To more clearly illustrate the specific embodiments of this utility model or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this utility model. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0020] Figure 1 A schematic diagram of an invertible electrochemical coalescence coupled oilfield produced water treatment device;

[0021] Figure 2 A schematic diagram of a three-dimensional structure of an invertible electrochemical coalescence coupled oilfield produced water treatment device;

[0022] Figure 3 A cross-sectional view of a reversible electrochemical coalescence coupled oilfield produced water treatment device;

[0023] Figure 4 This is a cross-sectional view of the coalescing plate assembly;

[0024] Figure 5 This is a schematic diagram of the electrode plate assembly.

[0025] Figure 6 This is a schematic diagram of the internal structure of the ring-shaped component;

[0026] Figure 7 This is a schematic diagram of the structure of the anode plate and the cathode plate;

[0027] Figure 8 A schematic diagram of the arc-shaped fixing strip, fixing block, and screw;

[0028] Figure 9 This is a structural diagram of the motor and the tank.

[0029] Figure 10 This is a schematic diagram of the motor cleaning device;

[0030] Figure 11 This is a schematic diagram of the overall motor cleaning device;

[0031] Figure 12 A sectional view showing the installation of the end tube, threaded rod, and sealed bearing;

[0032] Figure 13 A schematic diagram of the structure of the motor, threaded rod, and slider;

[0033] Reference numerals: 1. Tank body; 2. Outlet; 3. Inlet; 4. Coalescing plate assembly; 5. Electrode plate assembly; 6. Electrode cleaning mechanism; 11. Oil outlet; 12. Sewage outlet; 13. Oil baffle; 14. Sewage baffle; 15. Mounting end pipe; 41. Ring body; 42. Coalescing corrugated plate; 43. Groove; 51. Annular component; 511. Pipe body; 53. Terminal block; 54. Arc-shaped fixing strip; 55. Fixing block; 56. Socket; 57. Screw; 58. 581. Anode plate; 582. Anode conductive plate; 59. Cathode plate; 591. Cathode support plate; 592. Cathode conductive plate; 61. Motor; 62. Sealed bearing; 63. Threaded rod; 64. Slider; 66. Bracket; 67. Slide rail; 68. Slide plate; 69. Guide block; 70. Guide groove; 71. Mounting plate; 72. Water spray pipe; 73. Water spray hole; 74. Water supply pipe; 75. Horizontal pipe; 76. Main pipe; 8. Control cabinet. Detailed Implementation

[0034] The technical solution of this utility model will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this utility model. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this utility model.

[0035] In the description of this utility model, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the accompanying drawings and are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0036] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0037] The present invention will be further explained below with reference to specific embodiments.

[0038] like Figures 1-13As shown in the figure, this embodiment provides a reversible electrochemical coalescence coupled oilfield produced water treatment device, including a tank 1. Outlets 2 and inlets 3 are respectively provided on the two side walls of the tank 1. A coalescence plate assembly 4, an electrode plate assembly 5, and an electrode cleaning mechanism 6 are sequentially arranged along the water flow direction inside the tank 1. The electrode cleaning mechanism 6 cleans the electrode plate assembly 5. The electrode plate assembly 5 includes several vertically staggered anode plates 58 and cathode plates 59. Terminals 53 are respectively provided at the top of the anode plates 58 and cathode plates 59. The terminals 53 extend out of the tank 1 and are connected to the terminals of a control cabinet 8 via wires. The power supply in the control cabinet 8 is a DC power system (existing equipment), with an input voltage of 220 volts and an output voltage of 0~20 volts. The current and voltage are adjustable. The output terminals of the power supply are connected to the terminals 53 on the top surfaces of the anode conductive plate 582 and the cathode conductive plate 592 via wires. The control cabinet 8 controls the periodic reversal of the polarity of the anode plate 58 and the cathode plate 59 to achieve reversible operation. The device effectively promotes the coalescence of oil droplets in produced water by using fiberglass corrugated plates 42 in the coalescence plate assembly 4, thereby improving oil-water separation efficiency. Electrode plate assembly 5 generates strong oxidizing substances through electrochemical reactions, killing SRB (sulfuric acid blight) and removing corrosive, scaling components and harmful substances such as Fe²⁺ ions without the addition of chemical agents. This stabilizes the water quality and further removes corrosive components and pollutants from the water. This synergistic effect improves treatment effectiveness and efficiency, ensuring stable and compliant water quality after treatment. It solves the problems of unstable water quality and low compliance rate in traditional processes. Furthermore, the control cabinet 8 controls the periodic reversal of the anode and cathode, actively reversing the electrode reaction direction, effectively preventing problems such as anode sulfur deposition, cathode scaling, and crude oil contamination of the electrodes, extending electrode lifespan, and reducing equipment operating costs.

[0039] like Figure 3 , Figure 4As shown, in this embodiment, the coalescing plate assembly 4 includes a ring 41. The two side walls of the ring 41 are adapted to fit the inner wall of the tank 1. Gaps are provided between the top and bottom of the ring 41 and the tank 1. A plurality of vertically arranged coalescing corrugated plates 42 are uniformly arranged on the inner wall of the ring 41. The direction of the grooves 43 in the coalescing corrugated plates 42 is at a 45° angle to the horizontal plane, and the directions of the grooves 43 in adjacent coalescing corrugated plates 42 intersect at a 90° angle. The coalescing corrugated plates 42 are made of fiberglass. Large oil particles, after coarsening, float to the top along the grooves 43 in the coalescing corrugated plates 42, while sediment particles sink to the bottom along the channels. The coalescing corrugated plates 42 are made of fiberglass, a material that not only has good corrosion resistance but also highly efficient oil droplet coalescing performance. The grooves 43 of two adjacent plates of the coalescing corrugated plate 42 intersect at a 90° angle, and the direction of each groove 43 is at a 45° angle to the horizontal plane. This guides the water flow to form a thin, tortuous flow, promoting the wetting, collision, and coalescence of oil droplets on the corrugated plate surface, thereby significantly improving oil-water separation efficiency. This design not only reduces the burden of subsequent electrochemical treatment and extends the service life of the electrode plates, but also reduces the amount of chemical reagents used, thus reducing operating costs and maintenance workload.

[0040] like Figure 3 As shown, in this embodiment, an oil outlet 11 and a sludge outlet 12 are respectively provided at the top and bottom of the outer wall of the tank 1. The oil outlet 11 and the sludge outlet 12 are located between the coalescing plate assembly 4 and the electrode plate assembly 5, and an oil baffle 13 and a sludge baffle 14 are respectively provided on the rear side of the oil outlet 11 and the sludge outlet 12. The oil baffle 13 and the sludge baffle 14 are fixed to the inner wall of the tank 1. The oil baffle 13 forces the coalescing of the floating crude oil or the gas in the tank 1 to be discharged periodically or in small flow through the top oil outlet 11. The sludge baffle 14 intercepts the settled solid impurities and guides them away through the bottom sludge outlet 12, thereby achieving efficient separation and pre-removal of oil and sludge, greatly reducing the risk of crude oil and particulate matter entering the electrode area, reducing the problems of scale and oil sludge covering and clogging on the electrode plates, and ensuring the continuous and efficient operation of the electrochemical treatment unit.

[0041] like Figures 5-8As shown, in this embodiment, the electrode plate assembly 5 includes an annular component 51, and two tubes 511 are provided on the top surface of the annular component 51. Both the annular component 51 and the tubes 511 are made of polytetrafluoroethylene. The annular component 51 is tightly fitted into the inner wall of the tank 1. The inner wall of the annular component 51 is vertically and parallelly arranged with several anode plates 58 and cathode plates 59 to maximize the reaction area of ​​the plates and improve the electrochemical oxidation efficiency. Anode support plates 581 are provided on one side of the top surface of each of the anode plates 58. The top of the anode support plates 581 is connected to the bottom surface of the anode conductive plate 582. A cathode support plate 591 is provided on one side of the top surface of each of the cathode plates 59. The cathode support plates 591 and 581 are arranged opposite each other so that the anode conductive plate 582 and the cathode conductive plate 592 do not contact each other. The top of the cathode support plates 591 is connected to the bottom surface of the cathode conductive plate 592. There is a gap between the anode conductive plate 582 and the cathode conductive plate 592, which is greater than the minimum discharge distance between the plates. A low-voltage DC electrostatic field is formed between the plates, which is conducive to the directional movement and aggregation of charged particles. Both the anode conductive plate 582 and the cathode conductive plate 592 have terminal blocks 53 on their top surfaces. These terminal blocks 53 pass through the pipe body 511 and are connected to the control cabinet 8 via cables. The pipe body 511 and the terminal blocks 53 are sealed together. The terminal blocks 53 serve as through channels to ensure the sealing and insulation safety of the cables. The control cabinet 8 is located on one side of the tank body 1. The power supply for the anode conductive plate 582 and the cathode conductive plate 592 in the control cabinet 8 is a DC power system with an input voltage of 220 volts and an output voltage of 0~20 volts. The current and voltage are adjustable. The electrode plate assembly 5 also includes two arc-shaped fixing strips 54, which are correspondingly positioned on the lower sides of the anode plate 58 and the cathode plate 59. Multiple fixing blocks 55 are evenly arranged on the inner sidewalls of the arc-shaped fixing strips 54, with adjacent fixing blocks 55 forming a group. The two fixing blocks 55 in each group are spaced apart, thus forming an insertion port 56. The insertion port 56 is adapted to fit the bottom sidewalls of the anode plate 58 and the cathode plate 59. Through-bolts 57 are respectively provided at both ends of the two arc-shaped fixing strips 54, and the ends of the bolts 57 are fixed by nuts. Both the arc-shaped fixing strips 54 and the fixing blocks 55 are made of insulating material. The arc-shaped fixing strips 54 wrap around the electrode array on both sides to resist water flow impact and vibration, preventing electrode plate displacement and deformation.

[0042] like Figures 9-13As shown, in this embodiment, the electrode cleaning mechanism 6 includes a motor 61, which is fixed to the outer side of the side wall of the tank 1 where the outlet 2 is located. The outer wall of the tank 1 also has a mounting end pipe 15, inside which a sealed bearing 62 is installed. The output shaft of the motor 61 is fitted into the inner ring of the sealed bearing 62 and extends into the inner cavity of the tank 1, ensuring stable operation and sealing of the motor. A threaded rod 63 is provided at the end of the output shaft of the motor 61, and the threaded rod 63 is screwed into a threaded hole in the middle of the slider 64. This enables the horizontal movement of the water spray pipe 72, ensuring that the water spray pipe can cover the gap between the anode plate 58 and the cathode plate 59 for effective rinsing. A horizontal sliding plate 68 is provided on the bottom surface of the slider 64. At least one guide block 69 is provided on the top surface of the sliding plate 68 on both sides of the slider 64. A guide groove 70 is provided on the top surface of the guide block 69. A slide rail 67 on the bottom surface of the bracket 66 is slidably nested within the guide groove 70, ensuring smooth movement of the sliding plate 68 and the slider 64 and preventing deviation. One end of the bracket 66 is fixed to the inner side of the side wall of the tank 1, and the other end of the bracket 66 is rotatably connected to the end of the threaded rod 63. The bottom surface of the slide plate 68 is fixedly connected to the arc-shaped mounting plate 71. Multiple rows of horizontal pipes 75 are evenly arranged on the bottom surface of the mounting plate 71. Each horizontal pipe 75 is vertically connected to multiple vertical water spray pipes 72. Several water spray holes 73 are evenly opened on the pipe wall of each water spray pipe 72. The ends of the horizontal pipes 75 converge and connect to the main pipe 76. The main pipe 76 is connected to the water supply pipe 74. The water supply pipe 74 passes through the side wall of the tank 1 and is connected to the external high-voltage electrode cleaning fluid. The motor 61 drives the water spray pipes 72 to move horizontally to the gap between the anode plate 58 and the cathode plate 59 for rinsing.

[0043] This utility model also provides a reversible electrochemical coalescence coupling oilfield produced water treatment device. The working principle is as follows: the produced water enters the tank 1 from the inlet 3 and first passes through the coalescence plate assembly 4. The fiberglass coalescence corrugated plate 42 guides the water flow to form a thin layer flow. The surface characteristics of the coalescence corrugated plate 42 force the dispersed oil droplets to collide and coalesce into large oil droplets. The coalesced and floating crude oil is guided by the oil baffle 13 to the top oil outlet 11 for discharge. The settled solid impurities are intercepted by the baffle 14 and guided to the bottom sewage outlet 12 for periodic or small-flow discharge, realizing the pre-separation of oil and sludge. The pre-treated sewage enters the electrode plate assembly 5. The staggered anode plate 58 and cathode plate 59 generate strong oxidizing substances through electrochemical reaction after being energized, killing harmful microorganisms, removing corrosive and scaling components, and further stabilizing and purifying the water quality. The control cabinet 8 controls the periodic reversal of polarity to realize the reversible operation and prevent electrode scaling and pollution. After shutdown, the motor 61 of the electrode cleaning mechanism 6 drives the water spray pipe 72 to move horizontally, using high-pressure electrode cleaning fluid through the water supply pipe 74 to rinse the electrode plates, maintaining their cleanliness and conductivity. The entire electrochemical treatment process uses no chemical reagents, reducing operating costs and maintenance workload, and improving treatment efficiency and water quality stability.

[0044] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this utility model, and are not intended to limit it. Although the utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this utility model.

Claims

1. A reversible electrochemical coalescence coupled oilfield produced water treatment device, characterized in that, The tank (1) includes an outlet (2) and an inlet (3) on its two side walls. The inner cavity of the tank (1) is arranged in sequence along the water flow direction with a coalescing plate assembly (4), an electrode plate assembly (5), and an electrode cleaning mechanism (6). The electrode cleaning mechanism (6) cleans the electrode plate assembly (5). The electrode plate assembly (5) includes several vertically staggered anode plates (58) and cathode plates (59). The top of the anode plates (58) and cathode plates (59) are respectively provided with terminals (53). The terminals (53) extend out of the tank (1) and are connected to the terminal of the control cabinet (8) through wires. The control cabinet (8) controls the polarity of the anode plates (58) and cathode plates (59) to periodically change, so as to realize the reverse polarity operation.

2. The reversible electrochemical coalescence coupled oilfield produced water treatment device according to claim 1, characterized in that, The coalescing plate assembly (4) includes a ring (41), the two side walls of the ring (41) are adapted to fit the inner wall of the tank (1), and a gap is provided between the top and bottom of the ring (41) and the tank (1). Several vertically arranged coalescing corrugated plates (42) are evenly arranged on the inner wall of the ring (41). The direction of the groove (43) in the coalescing corrugated plate (42) is at a 45° angle to the horizontal plane, and the direction of the groove (43) in adjacent coalescing corrugated plates (42) is at a 90° angle to each other. The coalescing corrugated plate (42) is made of fiberglass.

3. The reversible electrochemical coalescence coupled oilfield produced water treatment device according to claim 2, characterized in that, An oil outlet (11) and a sludge outlet (12) are respectively provided at the top and bottom of the outer wall of the tank body (1). The oil outlet (11) and the sludge outlet (12) are located between the coalescing plate assembly (4) and the electrode plate assembly (5). An oil baffle (13) and a sludge baffle (14) are respectively provided on the rear side of the oil outlet (11) and the sludge outlet (12). The oil baffle (13) and the sludge baffle (14) are fixed to the inner wall of the tank body (1).

4. The reversible electrochemical coalescence coupled oilfield produced water treatment device according to claim 1, characterized in that, The electrode plate assembly (5) includes an annular part (51), and two tubes (511) are provided on the top surface of the annular part (51). Both the annular part (51) and the tubes (511) are made of polytetrafluoroethylene. The annular part (51) is tightly fitted into the inner wall of the tank (1).

5. The reversible electrochemical coalescence coupled oilfield produced water treatment device according to claim 4, characterized in that, The inner wall of the annular component (51) is vertically and parallelly arranged with several anode plates (58) and cathode plates (59). Anode support plates (581) are provided on one side of the top surface of several anode plates (58). The top of several anode support plates (581) is connected to the bottom surface of anode conductive plates (582). Anode support plates (591) are provided on one side of the top surface of several cathode plates (59). The top of several cathode support plates (591) is connected to the bottom surface of cathode conductive plates (592). There is a gap between the anode conductive plates (582) and the cathode conductive plates (592).

6. The reversible electrochemical coalescence coupled oilfield produced water treatment device according to claim 5, characterized in that, Terminals (53) are provided on the top surfaces of both the anode conductive plate (582) and the cathode conductive plate (592). The terminals (53) pass through the pipe body (511) and are connected to the control cabinet (8) via cables. The control cabinet (8) is located on one side of the tank body (1). The power supply in the control cabinet (8) is a DC power supply system with an input voltage of 220 volts and an output voltage of 0~20 volts. The current and voltage are adjustable. The output terminals of the power supply are connected to the terminals (53) on the top surfaces of the anode conductive plate (582) and the cathode conductive plate (592) via wires.

7. The reversible electrochemical coalescence coupled oilfield produced water treatment device according to claim 6, characterized in that, The electrode plate assembly (5) also includes two arc-shaped fixing strips (54). The two arc-shaped fixing strips (54) are respectively set on the lower part of both sides of the anode plate (58) and the cathode plate (59). Multiple fixing blocks (55) are evenly arranged on the inner side wall of the arc-shaped fixing strips (54). Adjacent fixing blocks (55) are in pairs. The two fixing blocks (55) in each group are spaced apart to form a socket (56). The socket (56) is adapted to be inserted into the side wall of the bottom of the anode plate (58) and the cathode plate (59). The two ends of the two arc-shaped fixing strips (54) are respectively provided with through screws (57). The two ends of the screws (57) are fixed by nuts. The arc-shaped fixing strips (54) and the fixing blocks (55) are both made of insulating material.

8. The reversible electrochemical coalescence coupled oilfield produced water treatment device according to claim 1, characterized in that, The electrode cleaning mechanism (6) includes a motor (61), which is fixed on the outside of the side wall of the tank (1) where the outlet (2) is located. The side wall of the tank (1) is also provided with an installation end tube (15). A sealed bearing (62) is provided inside the installation end tube (15). The output shaft of the motor (61) is fitted into the inner ring of the sealed bearing (62) and extends to the inner cavity of the tank (1). A threaded rod (63) is provided at the end of the output shaft of the motor (61). The threaded rod (63) is screwed into the threaded hole in the middle of the slider (64).

9. The reversible electrochemical coalescence coupled oilfield produced water treatment device according to claim 8, characterized in that, A horizontal sliding plate (68) is provided on the bottom surface of the slider (64). At least one guide block (69) is provided on the top surface of the sliding plate (68) on both sides of the slider (64). A guide groove (70) is provided on the top surface of the guide block (69). The slide rail (67) provided on the bottom surface of the bracket (66) is slidably nested in the guide groove (70). One end of the bracket (66) is fixed to the inner side of the side wall of the tank (1), and the other end of the bracket (66) is rotatably connected to the end of the threaded rod (63).

10. A reversible electrochemical coalescence coupled oilfield produced water treatment device according to claim 9, characterized in that, The bottom surface of the slide plate (68) is fixedly connected to the arc-shaped mounting plate (71). Multiple rows of horizontal pipes (75) are evenly arranged on the bottom surface of the mounting plate (71). Each horizontal pipe (75) is vertically connected to multiple vertical water spray pipes (72). Several water spray holes (73) are evenly opened on the pipe wall of each water spray pipe (72). The ends of the horizontal pipes (75) converge and connect to the main pipe (76). The main pipe (76) is connected to the water supply pipe (74). The water supply pipe (74) passes through the side wall of the tank (1) and is connected to the external high-voltage electrode cleaning liquid. The motor (61) drives the water spray pipe (72) to move horizontally to the gap between the anode plate (58) and the cathode plate (59) for rinsing.

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