Oil and gas field high emulsification sewage treatment device

Abstract

The application belongs to the technical field of oil and gas exploitation, and particularly relates to a high-emulsification sewage treatment device for oil and gas fields. The high-emulsification sewage treatment device for oil and gas fields comprises an electric flocculation cabin and a cyclone cabin, a cyclone pipe is arranged on the electric flocculation cabin, sewage enters the electric flocculation cabin through the cyclone pipe, an outer ring electrode, an inner ring electrode and a center ring electrode are sequentially and fixedly arranged in the electric flocculation cabin in a spaced coaxial manner from outside to inside, the polarity of the outer ring electrode and the center ring electrode is opposite to the polarity of the inner ring electrode, after the sewage enters the electric flocculation cabin, the sewage first passes through the annular space between the outer ring electrode and the inner ring electrode, and then passes through the annular space between the inner ring electrode and the center ring electrode. The application can efficiently separate impurities in the sewage, and occupies a small space.

Description

Technical Field

[0001] This invention belongs to the field of oil and gas extraction technology, specifically, it relates to a high-emulsification wastewater treatment device for oil and gas fields. Background Technology

[0002] In oil and gas development, with the continuous breakthroughs and widespread application of fracture network, horizontal well cross-layer, and horizontal well multi-stage fracturing technologies, unconventional oil and gas such as shale oil and shale gas have gradually been exploited on a large scale. During the production process, a large amount of highly emulsified wastewater, represented by fracturing flowback fluid, is generated.

[0003] Fracturing flowback fluid, as operational wastewater generated after oil and gas field production enhancement measures, contains gum, preservatives, breaker agents, petroleum compounds, and various other chemical additives. It carries a large amount of sand and solid impurities from the formation and is characterized by high viscosity, high emulsification degree, high solid content, difficulty in oil-cement separation, and large fluctuations in water quality. It needs to be disposed of in a compliant and reasonable manner, mainly through two methods: reinjection and centralized transportation and treatment.

[0004] When reinjecting fracturing flowback fluid, the selection of the reinjection formation is critical, making it unsuitable for large-scale reinjection and posing significant environmental risks. Therefore, it is usually transported by tanker truck to a joint station for centralized treatment of fracturing flowback fluid.

[0005] Before fracturing flowback fluid enters the combined station system, it needs to be pretreated to remove solid impurities, suspended solids, and colloids. This is to prevent direct access from disrupting the normal operation of the production system, consuming large amounts of treatment agents, affecting the oil-water separation effect, and causing the treated water quality to fail to meet standards, thus affecting the effectiveness of water injection development.

[0006] Commonly used pretreatment methods for fracturing flowback fluid include magnetic separation, suspended sludge (SSF) method, and biochemical method. Magnetic separation consumes a large amount of magnetic powder, which is difficult to recover, resulting in high treatment costs and large sludge production. The SSF method is greatly affected by water quality fluctuations and still requires the addition of flocculants and coagulants to form flocs, making it difficult to control the sludge layer effect. Fracturing flowback fluid has poor biodegradability, requiring the addition of certain nutrients when using the biochemical method, resulting in high treatment costs and treatment effectiveness greatly affected by water temperature and ambient temperature.

[0007] Therefore, the development trend of highly emulsified wastewater treatment technologies, represented by fracturing flowback fluid, is to efficiently capture impurities, achieve rapid floc separation, purify water, concentrate sludge, and realize on-site treatment and on-site reinjection of purified water. Summary of the Invention

[0008] To address the technical problems described above, this invention aims to provide a high-emulsification wastewater treatment device for oil and gas fields, which can efficiently demulsify and separate impurities from wastewater, while occupying a small space.

[0009] This invention is particularly suitable for the separation and treatment of oil and cement in wastewater generated from operations such as fracturing, drilling, acidizing, and well washing. It is also suitable for conventional wastewater treatment in offshore platforms with high solid content, strict water quality indicators, and limited space, as well as in skid-mounted sites. It is especially suitable for wastewater treatment with high emulsified oil content and high solid impurity content.

[0010] According to the present invention, a high-emulsification wastewater treatment device for oil and gas fields is provided, comprising an electrocoagulation chamber and a cyclone chamber. A cyclone tube is provided on the side wall of the electrocoagulation chamber, and wastewater enters the electrocoagulation chamber through the cyclone tube. An outer annular electrode, an inner annular electrode, and a central annular electrode are coaxially fixedly arranged at intervals from the outside to the inside of the electrocoagulation chamber. The polarities of the outer annular electrode and the central annular electrode are opposite to those of the inner annular electrode. After the wastewater enters the electrocoagulation chamber, it first passes through the annular space between the outer annular electrode and the inner annular electrode, and then passes through the annular space between the inner annular electrode and the central annular electrode.

[0011] In a preferred embodiment, a baffle tube and a central column tube are fixedly and coaxially at intervals inside the electrocoagulation chamber. The central column tube is located inside the baffle tube. The outer annular electrode is fixedly disposed on the inner wall of the electrocoagulation chamber, the inner annular electrode is fixedly disposed on the baffle tube, and the central annular electrode is fixedly disposed on the outer wall of the central column tube.

[0012] In a preferred embodiment, a sludge collection chamber is provided below the electrocoagulation chamber, and the electrocoagulation chamber and the sludge collection chamber are separated by a sludge hopper. The sludge hopper is a cone-shaped structure with its tip pointing downwards, and a sludge collection port is provided at the lower end of the sludge hopper.

[0013] In a preferred embodiment, the baffle is configured as a cone shape with the tip pointing downwards, and a mud-sliding pipe is fixedly provided at the lower end of the baffle. The mud-sliding pipe extends downwards through the mud-collecting port and enters the mud-collecting chamber.

[0014] In a preferred embodiment, a cyclone chamber is provided above the electrocoagulation chamber, and at least one gas injection cyclone is provided inside the cyclone chamber. The central column extends upward into the cyclone chamber and is connected to the gas injection cyclone.

[0015] In a preferred embodiment, a plurality of branch pipes are uniformly arranged along the circumferential direction at the top end of the central column, and each branch pipe is connected to each of the gas injection cyclones.

[0016] In a preferred embodiment, a gas injection distribution chamber and a compressor are provided at the top of the cyclone chamber. The gas injection distribution chamber is connected to each gas injection cyclone. The compressor pressurizes the gas at the top of the cyclone chamber and delivers it into the gas injection distribution chamber. The gas injection distribution chamber then injects the gas into each of the gas injection cyclones.

[0017] In a preferred embodiment, a microbubble generator is provided on the cyclone tube, and the microbubble generator is connected to the top of the cyclone chamber via a return gas pipe.

[0018] In a preferred embodiment, oil drain pipes are provided at the upper part of the cyclone chamber and the upper part of the electrocoagulation chamber. Gas distributors are provided on both oil drain pipes. One end of each gas distributor is connected to the return gas pipe, and the other end is connected to the oil drain port.

[0019] In a preferred embodiment, a water outlet pipe is provided on the wall of the cyclone chamber, and the water outlet pipe is located below the gas injection cyclone.

[0020] Compared with the prior art, the advantages of this application are as follows.

[0021] This invention features annular electrodes within an electrocoagulation chamber, and swirling tubes tangentially positioned on the chamber walls. Wastewater entering the chamber through these swirling tubes undergoes swirling flotation separation. Subsequently, the wastewater swirls and electrocoagulates more effectively within the annular space between adjacent annular electrodes. This eliminates the need for a separate swirling space for the wastewater and enhances the electrocoagulation reaction through the turbulent effect of the swirling flow, significantly reducing the volume of the electrocoagulation chamber. In other words, the annular electrode structure combines the advantages of a swirling flotation flow field and a large contact area, allowing the electrocoagulation oil removal reaction to be completed quickly under more thorough contact conditions, forming oil-containing flocs.

[0022] Furthermore, the air-injection cyclone installed in the cyclone chamber of this invention can separate residual tiny oil droplets and water in wastewater. The gas injected into the air-injection cyclone enables the wastewater to undergo pressure dissolved air flotation, and, in conjunction with the cyclone structure of the air-injection cyclone, provides the wastewater with a high multiple of gravitational acceleration, generating strong cyclone separation. The air-injection cyclone is highly efficient and small in size, thus making the overall footprint of this invention small.

[0023] Meanwhile, the present invention has many advantages over the traditional flat plate electrode arrangement.

[0024] Traditional flat-plate electrode arrangements have flow dead zones, reducing the effective electrocoagulation reaction contact area of ​​the electrodes. This invention uses annular electrodes combined with swirling flow to ensure that wastewater makes full contact with the electrode plates "ring by ring, layer by layer," thus maximizing the effective working area of ​​the annular electrodes.

[0025] With flat-plate electrodes, the distance between them is small, and the sewage flow is mostly laminar flow with a low Reynolds number. However, the annular electrode set in this invention, combined with the swirling effect, makes the sewage treatment process turbulent, allowing the electrocoagulation reaction products to leave the electrode and diffuse more quickly, increasing the probability of the electrocoagulation reaction products capturing and flocculating oil droplets and suspended impurities in the sewage. Attached Figure Description

[0026] The present invention will now be described with reference to the accompanying drawings.

[0027] Figure 1 A schematic diagram of an embodiment of a wastewater treatment apparatus according to the present invention is shown.

[0028] In the picture:

[0029] 1. Inlet pipe; 2. Booster pump; 3. Microbubble generator; 4. Cyclone tube; 5. Electrocoagulation chamber; 6. Baffle tube; 601. Conical baffle section; 602. Cylindrical baffle section; 61. Inner annular electrode; 62. Sludge sliding pipe; 63. Low-resistance one-way valve; 7. Outer annular electrode; 8. Sludge collection chamber; 81. Sludge sliding hopper; 82. Sludge collection port; 83. Sludge discharge pipe; 9. Central column tube; 91. Central annular electrode; 92. Branch pipe; 10. Air injection cyclone; 101. Cyclone inlet; 102. Air injection port; 1 03. Swirl underflow outlet; 104. Swirl overflow outlet; 11. Water outlet pipe; 12. Cover flange; 13. Gas injection circulation pipe; 14. Compressor; 15. Gas injection distribution chamber; 16. Gas injection pipe; 17. Oil collection tank; 18. Oil discharge pipe; 19. Gas distribution manifold; 191. First gas distribution manifold; 192. Second gas distribution manifold; 20. Oil discharge port; 21. Return gas pipe; 22. Swirl chamber; 23. Explosion-proof wiring port; 24. Power supply; 25. Connecting flange; 100. Oil and gas field high emulsification wastewater treatment device.

[0030] In this application, all drawings are schematic and are used only to illustrate the principles of the invention, and are not drawn to scale. Detailed Implementation

[0031] The invention will now be described with reference to the accompanying drawings.

[0032] It should be noted that the directional terms or qualifiers used in this application, such as "up," "down," "left," and "right," are all specific to the referenced material. Figure 1 In other words, they are not used to define the absolute position of the components involved, but can vary depending on the specific circumstances.

[0033] Figure 1 The structure of an oil and gas field hyperemulsified wastewater treatment device 100 according to the present invention is shown. (See diagram below.) Figure 1As shown, the oil and gas field high-emulsification wastewater treatment device 100 includes an electrocoagulation chamber 5 and a cyclone chamber 22. In this embodiment, the electrocoagulation chamber 5 is configured as a cylindrical shape.

[0034] A swirl tube 4 is installed tangentially on the wall of the electrocoagulation chamber 5. After the sewage enters the electrocoagulation chamber 5 through the swirl tube 4, a swirling air flotation effect is generated inside the electrocoagulation chamber 5.

[0035] Inside the electrocoagulation chamber 5, an outer ring electrode 7, an inner ring electrode 61, and a central ring electrode 91 are coaxially fixed in sequence from the outside to the inside. The polarity of the outer ring electrode 7 and the central ring electrode 91 is opposite to that of the inner ring electrode 61.

[0036] After the wastewater enters the electrocoagulation chamber 5 through the cyclone pipe 4, it first passes through the annular space between the outer annular electrode 7 and the inner annular electrode 61, and then through the annular space between the inner annular electrode 61 and the central annular electrode 91. While making full use of the internal space of the electrocoagulation chamber 5, it does not hinder the swirling of the wastewater. It combines the advantages of the swirling air flotation flow field and the large contact area, allowing the electrocoagulation oil removal reaction to be completed in a short time under more sufficient contact conditions, forming oil-containing flocs.

[0037] Specifically, one end of the cyclone tube 4 is connected to the electrocoagulation chamber 5, and the other end is equipped with a booster pump 2. An inlet pipe 1 is located at the front end of the booster pump 2. A microbubble generator 3 is connected in series on the cyclone tube 4. During operation, wastewater enters the inlet pipe 1, is pressurized by the booster pump 2, and then enters the microbubble generator 3 to form dissolved air water, which finally enters the electrocoagulation chamber 5 through the cyclone tube 4. The dissolved air water released by the cyclone tube 4 into the electrocoagulation chamber 5 releases a large number of microbubbles, which come into full contact with the wastewater under the action of cyclone, adhering to oil droplets and suspended solids in the water and accelerating their floating. The density difference is used to promote the separation and sedimentation of flocs, sludge, and large-diameter solids from the wastewater.

[0038] In this embodiment, a power supply 24 is provided outside the electrocoagulation chamber 5. The cathode or anode of the power supply 24 is electrically connected to the outer annular electrode 7 and the central annular electrode 91, and the other electrode of the power supply 24 is electrically connected to the inner annular electrode 61. Specifically, an explosion-proof wiring port 23 is provided on the wall of the electrocoagulation chamber 5, and the wires connecting the power supply 24 to each electrode enter the electrocoagulation chamber 5 through the explosion-proof wiring port 23.

[0039] According to the present invention, a baffle 6 and a central column tube 9 are fixedly and coaxially at intervals inside the electrocoagulation chamber 5, with the central column tube 9 located inside the baffle 6. An outer annular electrode 7 is fixedly disposed on the inner wall of the electrocoagulation chamber 5, an inner annular electrode 61 is fixedly disposed on the baffle 6, and a central annular electrode 91 is fixedly disposed on the outer wall of the central column tube 9.

[0040] In one specific embodiment, the baffle 6 includes a conical baffle section 601 and a cylindrical baffle section 602 disposed at the top of the conical baffle section 601. The inner annular electrode 61 comprises two layers, respectively disposed on the inner wall and outer wall of the cylindrical baffle section 602. The inner annular electrode 61 disposed on the inner wall of the cylindrical baffle section 602 cooperates with the central annular electrode 91, and the inner annular electrode 61 disposed on the outer wall of the cylindrical baffle section 602 cooperates with the outer annular electrode 7.

[0041] In another specific embodiment, the baffle 6 includes a conical baffle section 601. That is, in this embodiment, the baffle 6 does not include a cylindrical baffle section 602, and the inner annular electrode 61 is directly fixedly disposed on the top of the conical baffle section 601. The inner annular electrode 61 can cooperate with the outer annular electrode 7 and the central annular electrode 91 respectively.

[0042] The central column tube 9 is fixedly connected to the top of the electrocoagulation chamber 5, the baffle tube 6 is fixedly connected to the wall of the electrocoagulation chamber 5 via a fixing frame (not shown in the figure), and the vortex tube 4 is located below each electrode. The fixing frame is located below the vortex tube 4 to reduce the influence of the fixing frame on the sewage vortex.

[0043] The outer ring electrode 7, the inner ring electrode 61, and the central ring electrode 91 are insulated from the material of the device body to ensure current density and electric field effect.

[0044] According to the present invention, a sludge collection chamber 8 is provided below the electrocoagulation chamber 5, and the electrocoagulation chamber 5 and the sludge collection chamber 8 are separated by a sludge hopper 81. The sludge hopper 81 is a cone shape with its tip pointing downwards, and a sludge collection port 82 is provided at the lower end of the sludge hopper 81. After the solid phase impurities separated from the sewage fall onto the sludge hopper 81, they enter the sludge collection chamber 8 through the sludge collection port 82 under the guidance of the sludge hopper 81.

[0045] The baffle 6 is a cone shape with the tip pointing downwards. A mud-sliding pipe 62 is fixedly installed at the lower end of the baffle 6. The mud-sliding pipe 62 extends vertically downwards through the mud collection port 82 and enters the mud collection chamber 8.

[0046] The outer diameter of the mud-sliding pipe 62 is smaller than the diameter of the mud-collecting port 82, thus creating a gap between the mud-sliding pipe 62 and the mud-collecting port 82.

[0047] In this setup, wastewater enters the electrocoagulation chamber 5 through the cyclone pipe 4 and begins cyclone flotation. The annular electrode structure combines the advantages of both the cyclone flotation flow field and the large contact area, allowing the electrocoagulation oil removal reaction to be completed in a short time under more sufficient contact conditions, forming oil-containing flocs. Due to the presence of the baffle 6, wastewater can only flow upward through the annular space between the inner annular electrode 61 and the outer annular electrode 7. During this process, the polynuclear polymer hydroxide generated by the electrochemical reaction between the inner annular electrode 61 and the outer annular electrode 7 has a good flocculation effect. It reacts with most of the oil droplets, suspended solids, and large-diameter solids in the wastewater under the promotion of the cyclone flotation flow field, adhering and removing the oil droplets and suspended impurities in the wastewater, forming a sludge phase that moves downward and eventually falls onto the sludge hopper 81, then enters the sludge collection chamber 8 through the sludge collection port 82.

[0048] After passing through the swirling air flotation and first electrocoagulation between the inner annular electrode 61 and the outer annular electrode 7, the wastewater flows into the annular space between the inner annular electrode 61 and the central annular electrode 91 through the gap between the top of the inner annular electrode 61 and the top of the electrocoagulation chamber 5. During this process, the wastewater undergoes secondary electrocoagulation between the inner annular electrode 61 and the central annular electrode 91, and the resulting solid phase (sludge phase) impurities move downwards and eventually fall into the baffle 6, then enter the sludge collection chamber 8 through the sludge sliding pipe 62.

[0049] During the above process, oil droplets separated from the wastewater float to the top of the electrocoagulation chamber 5 to form an oil layer, which is then discharged through the oil drain pipe 18 located on the upper wall of the electrocoagulation chamber 5. Most of the oil droplets and suspended impurities in the wastewater are removed without the addition of chemicals.

[0050] In a preferred embodiment, a low-resistance one-way valve 63 is connected in series on the sludge pipe 62. The specific structure of the low-resistance one-way valve 63 is existing technology. Its resistance is very small, and the hydrostatic pressure above it and the gravity of the sludge are enough to open the low-resistance one-way valve 63, allowing the sludge to flow into the sludge collection chamber 8 in one direction.

[0051] The low-resistance single-flow valve 63 can prevent fluctuations in the inlet water pressure of the cyclone pipe 4 during production, which could cause the wastewater entering the electrocoagulation chamber 5 to flow upward through the sludge pipe 62 without being effectively treated according to the designed flow field path.

[0052] The separated sludge is concentrated in the sludge collection chamber 8. As the amount of sludge increases, the water phase is squeezed out of the sludge collection port 82 and the water content of the sludge is continuously reduced, thereby reducing the subsequent transportation and treatment costs.

[0053] A sludge discharge pipe 83 is installed at the bottom of the sludge collection chamber 8. An electric valve (not shown in the figure) is installed on the sludge discharge pipe 83. The opening or closing of the electric valve is controlled according to the amount of sludge, thereby controlling the intermittent sludge discharge time. If the amount of sludge is large, the electric valve can be kept open to achieve continuous sludge discharge.

[0054] In a preferred embodiment of the present invention, a cyclone chamber 22 is provided above the electrocoagulation chamber 5, and at least one gas injection cyclone 10 is provided inside the cyclone chamber 22. The central column tube 9 extends upward into the cyclone chamber 22 and is connected to the gas injection cyclone 10.

[0055] like Figure 1 As shown, multiple branch pipes 92 are evenly arranged along the circumferential direction at the top of the central column pipe 9, and the central axis of each branch pipe 92 is perpendicular to the central axis of the central column pipe 9.

[0056] Accordingly, multiple gas-injecting cyclones 10 are evenly arranged in the cyclone chamber 22 along the circumferential direction, and each branch pipe 92 is connected to each gas-injecting cyclone 10, and each branch pipe 92 is arranged along the tangential direction of each gas-injecting cyclone 10. In this embodiment, each branch pipe 92 is connected to the cyclone inlet 101 of each gas-injecting cyclone 10.

[0057] According to the present invention, an injection distribution chamber 15 and a compressor 14 are provided at the top of the cyclone chamber 22. The injection distribution chamber 15 is connected to each injection cyclone 10. The compressor 14 pressurizes the gas at the top of the cyclone chamber 22 and delivers it into the injection distribution chamber 15. The injection distribution chamber 15 then injects the gas into each injection cyclone 10. It is easy to understand that the pressurized gas is injected into each injection cyclone 10 in a tangential direction. On the one hand, dissolved air water is formed, which can increase the contact opportunity between bubbles and oil droplets. On the other hand, in conjunction with the cyclone structure of the injection cyclone 10, the cyclone force of the sewage in each injection cyclone 10 is enhanced, and strong cyclone injection flotation is performed to promote oil-water separation.

[0058] Specifically, a cover flange 12 is sealed and fixed on the top of the cyclone chamber 22, and the gas injection distribution chamber 15 is fixedly installed on the cover flange 12.

[0059] An injection circulation pipe 13 is provided outside the cyclone chamber 22. One end of the injection circulation pipe 13 is connected to the top gas phase space of the cyclone chamber 22 through the cover flange 12, and the other end is connected to the injection distribution chamber 15. The compressor 14 is connected in series on the injection circulation pipe 13.

[0060] Multiple gas injection pipes 16 are evenly arranged along the circumference at the lower part of the gas injection distribution chamber 15, and the number of gas injection pipes 16 corresponds one-to-one with the number of gas injection cyclones 10.

[0061] The gas-injecting cyclone separator 10 includes a large conical section and a small conical section located below the large conical section. Gas injection ports 102 are provided on the side walls of both the large and small conical sections. The upper end of the gas injection pipe 16 is connected to the gas injection distribution chamber 15, and the lower end is divided into two pipes, which are respectively connected to the gas injection ports 102 of the large conical section and the gas injection ports 102 of the small conical section.

[0062] Preferably, a microporous aeration membrane (not shown in the figure) can be installed at the air injection port 102. The microporous aeration membrane can further reduce the size of the bubbles, which is beneficial to the adhesion of bubbles and oil droplets.

[0063] The specific structure of the microporous aeration membrane is existing technology and will not be described in detail here. The swirl inlet 101 is tangentially positioned at the top of the large conical section of the aeration hydrocyclone 10. A swirl overflow port 104 is located at the upper end of the large conical section of the aeration hydrocyclone 10 for discharging the oil phase. A swirl underflow port 103 is located at the lower end of the small conical section of the aeration hydrocyclone 10 for discharging the aqueous phase.

[0064] According to the present invention, a return gas pipe 21 is also provided on the cover flange 12. One end of the return gas pipe 21 is connected to the gas phase space at the top of the cyclone chamber 22 through the cover flange 12, and the other end extends downward and is connected to the microbubble generator 3 provided at the front end of the cyclone tube 4.

[0065] In one specific embodiment, an oil drain pipe 18 is provided on the upper part of the cyclone chamber 22 and the upper part of the electrocoagulation chamber 5. A gas separator 19 is provided on both oil drain pipes 18. The gas outlet port of the gas separator 19 is connected to the return gas pipe 21, and the liquid outlet port of the gas separator 19 is connected to the oil drain port 20.

[0066] like Figure 1 As shown, in this embodiment, the upper part of the gas distribution manifold 19 is the gas outlet port, and the lower part is the liquid outlet port. For ease of explanation, the gas distribution manifold 19 connected to the electrocoagulation chamber 5 is referred to as the second gas distribution manifold 192, and the gas distribution manifold 19 connected to the cyclone chamber 22 is referred to as the first gas distribution manifold 191. The lower end of the first gas distribution manifold 191 is connected to the upper end of the second gas distribution manifold 192, the upper end of the first gas distribution manifold 191 is connected to the return gas pipe 21, and the lower end of the second gas distribution manifold 192 is provided with an oil drain port 20.

[0067] It is easy to understand that the internal structure of the gas separator 19 is existing technology. It can separate the gas and oil that escape after the swirl flotation in this invention, allowing the gas to move upward and return from the cover flange 12 to the top of the swirl chamber 22, thus avoiding the overflow of oily gas and pollution of the environment. These gases can also be used to supply the microbubble generator 3 and the gas swirl generator 10 for self-circulation, saving gas consumption.

[0068] According to the present invention, a water outlet pipe 11 is provided on the wall of the cyclone chamber 22, and the water outlet pipe 11 is located below the gas injection cyclone generator 10.

[0069] After the wastewater is treated by the electrocoagulation chamber 5 of this invention, most of the floating oil, most of the emulsified oil droplets and solid impurities are removed. The remaining small amount of fine emulsified oil droplets in the wastewater are highly emulsified and can enter the vortex chamber 22 above the electrocoagulation chamber 5 for removal by strong vortex air flotation.

[0070] In other words, when sewage passes through Figure 1 After passing through the annular space between the central annular electrode 91 and the inner annular electrode 61, the flow continues, passing through the gap between the lower end of the central annular electrode 91 and the baffle 6, then entering the central column tube 9 and flowing upward, passing through each branch tube 92 and entering each gas injection cyclone 10 respectively.

[0071] The gas used in the strong swirling air flotation in the air-injection cyclone separator 10 comes from the gas phase space at the top of the cyclone chamber 22. This gas is natural gas dissolved in the wastewater, thus solving the problem of dissolved oxygen corrosion in water caused by the introduction of oxygen in conventional air flotation.

[0072] The gas in the gas phase space at the top of the cyclone chamber 22 is drawn in and pressurized by the compressor 14 through the gas injection circulation pipe 13, and then enters the gas injection distribution chamber 15. Through multiple evenly distributed gas injection pipes 16, the pressurized gas is sent into the gas injection cyclone 10 through two gas injection ports 102 located in the large cone section and the small cone section.

[0073] Preferably, a microporous aeration membrane (not shown in the figure) can be installed at the air injection port 102. The microporous aeration membrane can further reduce the size of the bubbles, which is beneficial to the adhesion of bubbles and oil droplets.

[0074] The specific structure of the microporous aeration membrane is existing technology and will not be described in detail here.

[0075] After the wastewater enters the hydrocyclone 10 tangentially through the cyclone inlet 101, a strong vortex is formed under the action of the large and small cone sections. Due to the pressurization effect of the compressor, the gas entering through the air inlet 102 is fully dissolved in the wastewater under pressure and vortex action. Under the centrifugal force generated by the strong vortex, the heaviest aqueous phase is thrown onto the inner wall of the side of the hydrocyclone 10. During the movement of the aqueous phase towards the inner wall, the lighter dissolved bubbles and oil droplets in the water leave the aqueous phase and move towards the center. This process increases the collision opportunities between oil droplets and bubbles, forming a bubble-oil droplet adhesiosome with a lower density, thereby further accelerating the separation of oil droplets from the aqueous phase.

[0076] Ultimately, a distribution is formed with the water phase on the outside and oil droplets and bubbles on the inside, that is, the water ring on the outside and the oil core on the inside. The water phase flows from the underflow port 103 to the lower part of the vortex chamber 22, and finally flows out of the device from the outlet pipe 11.

[0077] The bubble-oil droplet adherents move upward and flow out from the vortex overflow port 104, rising to the liquid surface. The bubbles escape into the gas phase space at the top of the vortex chamber 22, which is used by the gas injection circulation pipe 13 and the return gas pipe 21.

[0078] The oil layer formed by the oil droplets flows into the gas separator 19 through the oil collection tank 17 and the oil discharge pipe 18. The separated gas flows upward along the return gas pipe 21 back to the top of the vortex chamber 22, or flows downward along the return gas pipe 21 to the microbubble generator 3. The oil phase flows downward and is discharged from the oil discharge port 20.

[0079] In a preferred embodiment, an electric valve (not shown in the figure) is installed at the oil drain port 20, and an oil-water interface meter (not shown in the figure) is installed on the top of the vortex chamber 22. The electric valve and the oil-water interface meter are connected in communication. The oil-water interface meter can generate different electrical signals according to the changes in the oil-water interface. The electric valve responds to these electrical signals and performs different opening and closing actions, thereby realizing automatic intermittent or continuous oil discharge according to the oil layer thickness.

[0080] It should be noted that the specific communication connection method between the oil-water interface meter and the electric valve is existing technology and is not a key technical point of this invention, so it will not be described in detail here.

[0081] In a preferred embodiment, the electrocoagulation chamber 5 and the cyclone chamber 22 are connected by a connecting flange 25, the central column tube 9 passes through the connecting flange 25, and the central column tube 9 and the connecting flange 25 are mutually sealed.

[0082] By setting the connecting flange 25, the electrocoagulation chamber 5 and the cyclone chamber 22 can be easily separated, making it easy to replace the outer annular electrode 7, the inner annular electrode 61 and the central annular electrode 91. Those skilled in the art can analyze the type of wastewater and use electrodes of different materials and with different positive and negative poles to treat different types of wastewater generated by different blocks, different processes and different operating methods.

[0083] The aeration cyclone separator 10 determines the final water treatment effect. During research and development, it was found that a smaller size resulted in better treatment performance and lower manufacturing costs. Therefore, the design concept was a combined, modular approach, with multiple aeration cyclones 10 used in combination. In actual operation, the top of the cyclone chamber 22 can be opened by disassembling the cover flange 12, allowing for the replacement of different specifications and quantities of aeration cyclones 10 according to different water volumes and qualities. Simultaneously, the compressor 14 can be replaced or the compressor motor frequency adjusted. Different boosting pressures are combined to achieve the optimal cyclone intensity and treatment effect.

[0084] In this embodiment, the oil collection tank 17 is fixedly installed on the upper part of the cyclone chamber 22, and works in conjunction with the electric valve of the oil outlet 20 and the oil-water interface meter on the upper part of the cyclone chamber 22 to ensure that there is a gas phase space between the oil layer liquid level and the cover flange 12 for use by the gas-using equipment.

[0085] In a specific embodiment provided by the present invention, the electrocoagulation chamber 5 has a specification of DN500×1200mm, the cyclone chamber 22 has a specification of DN500×800mm, and the oil and gas field high emulsification wastewater treatment device 100 has an overall footprint of 1000mm×1000mm×2300mm and a treatment capacity of 6m³. 3 / h. The outer annular electrode 7 and the central annular electrode 91 use aluminum anodes, and the inner annular electrode 61 uses a graphite cathode. The controlled voltage is 5-11V, and the current is 50-150A. Four gas-injecting cyclones 10 are set, evenly distributed along the circumference of the cyclone chamber 22. The processing capacity of a single gas-injecting cyclone 10 is 1.5m³. 3 / h.

[0086] Wastewater from fracturing flowback operations, such as pumped fluid, is pressurized to 0.7–1.0 MPa by booster pump 2, causing microbubble generator 3 to dissolve microbubbles in the wastewater. The return flow rate is 0.8–1.0 m³. 3 At a rate of / h, wastewater enters the electrocoagulation chamber 5 via a swirling flow. Between the outer annular electrode 7, the inner annular electrode 61, and the central annular electrode 91, swirling air flotation (bubble particle size 50–70 μm) and electrocoagulation separate the oil and cement. This process removes most of the oil droplets, suspended impurities, and large-particle solids without or with minimal chemical addition. The resulting sludge settles into the sludge collection chamber 8 for storage and concentration, while the oil droplets rise to form an oil layer, which is discharged from the oil drain pipe 18 at the top of the electrocoagulation chamber 5.

[0087] After most of the floating oil, emulsified oil, and solid impurities are removed in the electrocoagulation chamber 5, the wastewater is distributed into multiple aeration cyclones 10 through multiple branch pipes 92 at the top of the central column pipe 9. With the cooperation of the compressor 14 and the aeration distribution chamber 15, a strong swirling aeration flotation is formed. The gas pressure in the aeration pipe 16 ranges from 0.5 to 1 MPa, preferably 0.7 MPa. The purified water is discharged from the outlet pipe 11 at the bottom of the cyclone chamber 22, and the separated oil is discharged from the oil drain pipe 18 at the top of the cyclone chamber 22.

[0088] This invention primarily couples electrocoagulation, cyclone flotation, and sludge-water separation technologies. Under conditions of minimal or no chemical addition, a single unit achieves flocculation and demulsification, oil-cement separation, and efficient water treatment of highly emulsified wastewater generated from operations such as fracturing, drilling, acidizing, and well washing, while reducing the unit's space occupancy. It is suitable for conventional wastewater treatment on offshore platforms with high solids content, strict water quality standards, and limited space, as well as in skid-mounted environments. It is particularly suitable for wastewater treatment with high emulsified oil content and high solid impurity content.

[0089] This invention enables closed-loop oxygen isolation and continuous treatment, and features high efficiency, no or minimal chemical addition, self-circulating gas, and low operating costs.

[0090] In the description of this invention, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0091] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., 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 invention according to the specific circumstances.

[0092] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0093] Finally, it should be noted that the above description is merely a preferred embodiment of the present invention and does not constitute any limitation on the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A high-emulsification wastewater treatment device for oil and gas fields, characterized in that, The system includes an electrocoagulation chamber (5) and a cyclone chamber (22). A cyclone tube (4) is provided on the electrocoagulation chamber (5) along the tangential direction. Wastewater enters the electrocoagulation chamber (5) through the cyclone tube (4). A microbubble generator (3) is provided on the cyclone tube (4). The microbubble generator (3) is connected to the top of the cyclone chamber (22) through a return gas pipe (21). Inside the electrocoagulation chamber (5), an outer ring electrode (7), an inner ring electrode (61), and a central ring electrode (91) are coaxially fixed at intervals from the outside to the inside. The polarities of the outer ring electrode (7) and the central ring electrode (91) are opposite to those of the inner ring electrode (61). A sludge collection chamber (8) is provided below the electrocoagulation chamber (5). A baffle tube (6) and a central column tube (9) are fixedly and coaxially at intervals inside the electrocoagulation chamber (5). The central column tube (9) is located inside the baffle tube (6). The outer annular electrode (7) is fixedly installed on the inner wall of the electrocoagulation chamber (5). The inner annular electrode (61) is fixedly installed on the baffle tube (6). The central annular electrode (91) is fixedly installed on the central column tube (9). On the outer wall, the electrocoagulation chamber (5) and the sludge collection chamber (8) are separated by a sludge hopper (81). The sludge hopper (81) is a cone shape with its tip pointing downwards. A sludge collection port (82) is provided at the lower end of the sludge hopper (81). The baffle tube (6) is a cone shape with its tip pointing downwards. A sludge tube (62) is fixedly provided at the lower end of the baffle tube (6). The sludge tube (62) extends downwards through the sludge collection port (82) and enters the sludge collection chamber (8). After the wastewater enters the electrocoagulation chamber (5), it first passes through the annular space between the outer annular electrode (7) and the inner annular electrode (61), then through the annular space between the inner annular electrode (61) and the central annular electrode (91), and then enters the vortex chamber (22).

2. The oil and gas field high-emulsification wastewater treatment device according to claim 1, characterized in that, At least one gas injection cyclone (10) is provided inside the cyclone chamber (22), and the central column tube (9) extends upward into the cyclone chamber (22) and is connected to the gas injection cyclone (10).

3. The oil and gas field high-emulsification wastewater treatment device according to claim 2, characterized in that, Multiple branch pipes (92) are evenly arranged along the circumferential direction at the top of the central column (9), and each branch pipe (92) is connected to each of the gas injection cyclones (10).

4. The oil and gas field high-emulsification wastewater treatment device according to claim 2, characterized in that, A gas injection distribution chamber (15) and a compressor (14) are connected to each other at the top of the cyclone chamber (22). The gas injection distribution chamber (15) is connected to each gas injection cyclone (10). The compressor (14) pressurizes the gas at the top of the cyclone chamber (22) and delivers it into the gas injection distribution chamber (15). The gas injection distribution chamber (15) then injects the gas into each of the gas injection cyclones (10).

5. The oil and gas field high-emulsification wastewater treatment device according to claim 4, characterized in that, Oil drain pipes (18) are provided on the upper part of the vortex chamber (22) and the upper part of the electrocoagulation chamber (5). Gas separators (19) are provided on both oil drain pipes (18). One end of each gas separator (19) is connected to the return gas pipe (21), and the other end is connected to the oil drain port (20).

6. The oil and gas field high-emulsification wastewater treatment device according to claim 3, characterized in that, A water outlet pipe (11) is provided on the wall of the cyclone chamber (22), and the water outlet pipe (11) is located below the gas injection cyclone (10).

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