A coaxial cylindrical electrode variable-distance helical flow channel electrocoalescing device

Abstract

The application discloses a coaxial cylindrical electrode variable-pitch spiral flow channel electrocoalescing device, which is suitable for efficient separation of water-in-oil emulsion and is composed of a feeding section, an electrocoalescing section and a separation section. The core innovation lies in that the electrocoalescing section adopts a three-section variable-pitch spiral flow channel design of an outer moving guide section, an outer field coalescing section and a stable coalescing separation section, the pitch is increased by 30%-50% along the emulsion flow direction, and the spiral lift angle is 15-45 degrees. The outer electrode inner wall is coated with an oil-resistant coating; the inner and outer electrodes form an electric field, cooperate with the centrifugal force generated by the spiral flow channel, and realize the ladder-type cooperation of water phase outward movement, polarization coalescing and stable coalescing separation. The device solves the problems of poor flow field and electric field cooperation, low separation efficiency and insufficient stability of the traditional equipment, does not need external separation equipment, realizes the integration of "coalescing-separation", greatly improves the water phase removal rate and operation stability, reduces energy consumption, and is suitable for large-scale treatment of industrial scenes such as crude oil produced liquid.

Description

Technical Field

[0001] This patent relates to the field of petrochemical equipment technology, specifically focusing on water impurity separation equipment in crude oil produced fluid treatment. It is particularly suitable for electrostatic coalescence separation of water-in-oil emulsions and can be widely used in efficient dehydration processes of oilfield joint stations and oil and gas gathering and transportation systems. Background Technology

[0002] Traditional coaxial cylindrical electrostatic coalescers have shortcomings in the separation of water-in-oil emulsions. Their flow channels are mostly straight structures, lacking a helical configuration, resulting in a uniform flow velocity distribution. This makes it difficult to generate an effective centrifugal effect in the radial direction, hindering the migration and enrichment of the dispersed aqueous phase to the outside, thus limiting droplet collision and coalescence. Oil films easily adhere to the outer electrode surface, weakening the effective electric field strength and disrupting the local flow field structure, causing a significant decline in performance over time and insufficient long-term stability. These problems make traditional coaxial cylindrical electrostatic coalescers unsuitable for the industrial application requirements of efficient and stable separation of water-in-oil emulsions. Therefore, it is necessary to develop a coaxial cylindrical electrode variable-pitch helical flow channel electrostatic coalescer, which, by introducing a helical flow and electric field coupling mechanism, can simultaneously improve coalescence efficiency and operational stability.

[0003] Patent application CN108165299A, by inventors Zhang Ming et al., discloses a tubular compact electrostatic coalescer for electric field demulsification of W / O type emulsions. Its spiral electrode flow channel is composed of an insulating sleeve, a central shaft, high-voltage electrode spiral blades, and grounded electrode spiral blades. This application only adjusts the flow state through a single spiral blade structure, lacking a staged enhanced swirling design. Its targeted coalescence effect on water particles of different sizes is limited, making it difficult to further improve collisional coalescence efficiency. Furthermore, this application focuses on electric field demulsification and coalescence, only achieving the coalescence and growth of dispersed phase water particles. It lacks the ability to independently achieve efficient oil-water separation, requiring subsequent gravity sedimentation or centrifugal separation equipment, increasing the complexity of the overall process and equipment investment costs. Patent application CN105861035A, by inventors Zhuang Mengwen et al., discloses a cylindrical electrode electrostatic coalescer. This coalescer has a cylindrical outer shell and electrodes located within it. By controlling the residence time of the emulsion in an electric field and the magnitude of the electric field force, water droplets in the emulsion are allowed to collide and coalesce, forming larger particles that settle out, thus improving oil-water separation efficiency. However, the flow channel of this device is merely an annular space between the inner and outer electrodes, where the fluid is in a laminar flow state. It relies solely on slowing the flow rate to prolong the residence time to promote particle collision, lacking an active disturbance mechanism. The probability of water droplet collision in the dispersed phase is low, and the coalescing effect depends entirely on the electric field.

[0004] The advantage of this invention compared to the two aforementioned patent applications lies in its use of variable-pitch spiral blades. This allows dispersed phase droplets to collide and coalesce fully during flow, preventing large droplets from breaking apart, while also enabling rapid oil-water separation through flow dynamics. The device in this application integrates droplet coalescence and two-phase separation, reducing the complexity of the overall process. Summary of the Invention

[0005] To address the problems of traditional coaxial cylindrical electrostatic coalescers having a single flow rate, failing to generate centrifugal force to propel the aqueous phase outward, and exhibiting poor coordination between field strength and flow field, this invention provides a coaxial cylindrical electrode variable pitch spiral flow channel electrostatic coalescer that utilizes the centrifugal force provided by the spiral flow channel to propel the aqueous phase outward, thereby enhancing separation efficiency.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A coaxial cylindrical electrode variable pitch spiral flow channel electrostatic coalescence device is characterized in that the device comprises, from top to bottom, a feeding section, an electrostatic coalescence section, and a separation section;

[0008] In the aforementioned feeding section, the outer shell of the feeding section is cylindrical, with an emulsion inlet on the side wall of the outer shell, and the top cover is a sealed flange with an exhaust port. An internal electrode interface is set in the center of the top cover, and the bottom is connected to the electrostatic coalescence section through the flange.

[0009] The electrostatic coalescence section includes an outer electrode with a cylindrical structure. An inner electrode with a cylindrical structure and coaxial with the outer electrode is set at the center of the cylinder of the outer electrode. The upper end of the inner electrode passes through a flange and is connected to the inner electrode interface at the center of the top cover. The high-voltage cable of the high-voltage power supply is connected through the inner electrode interface. An outer electrode interface is provided on the flange at the bottom. The outer electrode is connected to the grounding cable of the high-voltage power supply through the outer electrode interface. Between the inner electrode and the outer electrode, three spiral blades are arranged in sequence along the flow direction of the water-in-oil emulsion. They are the spiral blades of the outward guiding section, the spiral blades of the external field coalescence section, and the spiral blades of the stable coalescence separation section. The pitch of each spiral blade increases sequentially.

[0010] The separation section is a cavity structure connected to the bottom flange of the electrostatic coalescence section. The lower part of the side wall of the outer shell of the separation section is provided with a water phase outlet, and the upper part of the side wall is provided with an oil phase outlet. A baffle is installed at the oil phase outlet.

[0011] The outer shell of the feeding section, the outer electrode of the electrostatic coalescence section, and the outer shell of the separation section are coaxial and have the same radial dimensions.

[0012] Preferably, the helix angle of the helical blades of the outward guiding section, the helical blades of the external field coalescence section, and the helical blades of the stable coalescence separation section is 15°-45°, and the increment of the pitch is 30%-50%.

[0013] Preferably, the external electrode is made of a conductive material, selected from stainless steel, aluminum alloy and titanium alloy.

[0014] Preferably, the inner electrode is a solid rod-shaped or hollow tubular structure, and is made of a metallic conductive material, selected from stainless steel, carbon steel, aluminum alloy and titanium alloy.

[0015] Preferably, the inner wall of the outer electrode is coated with an oil-resistant coating, and the coating material is selected from one of aluminum nitride-fluorocarbon composite, epoxy resin-polyethylene methylamine-titanium oxide.

[0016] In this invention, a high-voltage power supply 17 generates a high-voltage signal and a grounding signal, which are applied to the inner electrode 4 and the outer electrode 5 respectively through a high-voltage cable and a grounding cable to form an electrostatic coalescence system. Simultaneously, the small-pitch structure of the outward guiding section allows the water-in-oil emulsion to achieve a high flow velocity in this section, generating a strong centrifugal force to break the oil phase binding and push the polar aqueous phase in the emulsion towards the outer electrode. The medium-pitch structure of the outer field coalescence section allows the water-in-oil emulsion to achieve a medium flow velocity in this section, promoting the full polarization of the small aqueous phase and its collision and coalescence into large water droplets. The large-pitch structure of the stable coalescence separation section allows the water-in-oil emulsion to achieve a low flow velocity in this section, reducing the relative flow disturbance of the oil phase to avoid the breakage of large water droplets and facilitating the sedimentation and separation of the aqueous phase.

[0017] The anti-oil coating is used to reduce the adhesion of oil film on the inner wall of the electrode, which can reduce the amount of oil film adhering to the inner wall of the outer electrode by more than 80%.

[0018] The beneficial effects of this invention are as follows:

[0019] This invention provides a coaxial cylindrical electrode variable-pitch spiral flow channel electrostatic coalescence device. The spiral flow channel generates directional centrifugal force, efficiently propelling the aqueous phase towards the outer electrode and breaking the oil phase's confinement. The variable pitch design allows for dynamic adjustment of the flow rate, precisely adapting to the entire coalescence process and significantly improving the synergy between the field strength and the flow field. This enables the aqueous phase to fully absorb polarization energy, promoting the efficient coalescence of small aqueous phase particles into large water droplets, overcoming the efficiency bottleneck of traditional devices. Simultaneously, it avoids the breakage of large water droplets due to flow field disturbances, ensuring separation stability and effectively solving the core pain points of traditional devices. It is particularly suitable for the process of separating impurities from crude oil produced fluid in the petrochemical equipment technology field. Attached Figure Description

[0020] Figure 1 Schematic diagram of a coaxial cylindrical variable pitch spiral flow channel electrostatic coalescer

[0021] Among them, 1-feed section, 2-electrostatic coalescence section, 2-1-outward guiding section spiral blade, 2-2-outward coalescence section spiral blade, 2-3-stabilized separation section spiral blade, 3-separation section, 4-inner electrode, 5-outer electrode, 6-feed section shell, 7-emulsion inlet, 8-top cover, 9-exhaust port, 10-inner electrode interface, 11-outer electrode interface, 12-aqueous phase outlet, 13-baffle, 14-oil phase outlet, 15-separation section inner cavity, 16-separation section shell, 17-high voltage power supply, α-spiral angle.

[0022] Figure 2 Schematic diagram of the feeding section structure

[0023] Among them, 1-feed section, 6-feed section shell, 7-emulsion inlet, 8-top cover, 9-exhaust port, 10-internal electrode interface

[0024] Figure 3 Schematic diagram of the electrostatic coalescence segment structure

[0025] Among them, 2-electrostatic coalescence section, 2-1-outward guiding section spiral blade, 2-2-outer field coalescence section spiral blade, 2-3-stabilized coalescence separation section spiral blade, 4-inner electrode, 5-outer electrode, 11-outer electrode interface, α-helix angle.

[0026] Figure 4 Schematic diagram of the separated section structure

[0027] Among them, 3-separation section, 12-aqueous phase outlet, 13-baffle, 14-oil phase outlet, 15-separation section inner cavity, 16-separation section outer shell. Detailed Implementation

[0028] The present invention will be further described in detail below with reference to embodiments. It should be understood that the following embodiments are only used to further illustrate the present invention and should not be construed as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the content of the present invention still fall within the scope of protection of the present invention.

[0029] like Figure 1 The diagram shows the coaxial cylindrical electrode variable pitch spiral flow channel electrostatic coalescence device of the present invention. The device includes a feeding section 1, an electrostatic coalescence section 2, and a separation section 3, wherein...

[0030] The feeding section 1 includes an inner electrode 4, an outer electrode 5, an emulsion inlet 7, a top cover 8, an exhaust port 9, and an inner electrode interface 10; the electrostatic coalescence section is characterized in that it includes an inner electrode 4, an outer electrode 5, an outer electrode interface 11, an outward guiding section spiral blade 2-1, an external field coalescence section spiral blade 2-2, a stable coalescence separation section spiral blade 2-3, and a high-voltage power supply device 17, and the pitch of the three flow channels along the flow direction of the water-in-oil emulsion increases sequentially, that is, the outward guiding section has a small pitch structure, the external field coalescence section has a medium pitch structure, and the stable coalescence separation section has a large pitch structure; the separation section 3 includes an aqueous phase outlet 12, a baffle 19, an oil phase outlet 14, a separation section inner cavity 15, and a separation section outer shell 16.

[0031] The electrostatic coalescence section mainly consists of an outer electrode 5, an inner electrode 4, and spiral blades (2-1, 2-2, 2-3). The outer electrode 5, spiral blades (2-1, 2-2, 2-3), and inner electrode 4 are connected to form a spiral flow channel. The inner electrode 4 is connected to the high-voltage terminal of the high-voltage power supply device 17 through the inner electrode interface 10, and the outer electrode 5 is connected to the grounding terminal of the high-voltage power supply device 17 through the outer electrode interface 11. The high-voltage power supply device 17 generates a high-voltage signal and a grounding signal, which are applied to the inner electrode 4 and the outer electrode 5 respectively to form an electrostatic coalescence system.

[0032] The spiral angle α of the outward guiding section, the external field coalescence section, and the stable coalescence separation section is 15°-45°, and the pitch increases sequentially, with an increase of 30%-50%.

[0033] The small-pitch structure of the outer guiding section enables the water-in-oil emulsion to form a high flow velocity in this section, generating a strong centrifugal force to break the oil phase binding and promote the migration of the polar aqueous phase in the emulsion towards the outer electrode. The medium-pitch structure of the outer field coalescence section enables the water-in-oil emulsion to form a medium flow velocity in this section, which is adapted to the increased field strength, promoting the full polarization of the small aqueous phase and its collision and coalescence into large water droplets. The large-pitch structure of the stable coalescence separation section enables the water-in-oil emulsion to form a low flow velocity in this section, reducing the relative flow disturbance of the oil phase to avoid the breakage of large water droplets and facilitating the sedimentation and separation of the aqueous phase.

[0034] The external electrode 5 is a cylindrical structure made of conductive material, and the external electrode 5 is grounded.

[0035] The inner electrode 4 is a solid rod-shaped or hollow tubular structure, and is made of a metallic conductive material.

[0036] The entire inner wall of the outer electrode 5 is coated with an anti-oil coating (such as aluminum nitride-fluorocarbon composite, epoxy resin-polyethylene methylamine-titanium oxide, etc.), which reduces the adhesion of oil film on the inner wall of the outer electrode. The anti-oil coating can reduce the amount of oil film adhering to the inner wall of the outer electrode by more than 80%.

[0037] The separation section 3 is also a gravity settling section, which separates the aqueous phase and emulsion from the electrostatic coalescence section 2. With the help of the baffle 13, the aqueous phase is discharged from the aqueous phase outlet 12 and the oil phase is discharged from the oil phase outlet 14.

[0038] Example 1

[0039] This embodiment serves as an experimental device applied to a crude oil produced fluid treatment system in an oilfield. It performs electrostatic coalescence separation on water-in-oil (W / O) emulsions (crude oil density 890 kg / m³, aqueous phase density 1000 kg / m³, emulsion viscosity 50 mPa·s, inlet water content 35%), replacing the traditional electrostatic dehydrator. This achieves integrated coalescence-separation treatment, meeting the requirements for subsequent crude oil transportation and wastewater reinjection.

[0040] Total length of the device: 3 m (0.4 m for feeding section + 1.6 m for electrostatic coalescence section + 1 m for separation section)

[0041] External electrode: Conductive stainless steel (304) cylindrical structure, outer diameter 250mm, wall thickness 5mm, total length 1.6m (equal to the length of the electrostatic coalescence section), inner wall fully coated with aluminum nitride-fluorocarbon composite anti-oil coating, coating thickness 0.5mm.

[0042] Inner electrode: solid carbon steel rod structure, outer diameter 20 mm, total length 2 m (through the feed section and electrostatic coalescence section).

[0043] Feeding section: outer diameter of shell 250mm, wall thickness 5mm, nominal diameter of emulsion inlet DN100, nominal diameter of exhaust port DN20, top cover is connected by flange (PN1.6 MPa).

[0044] Separation section: Gravity settling section with a height of 1 m, an outer diameter of 250 mm, and a wall thickness of 5 mm. The nominal diameter of the water phase outlet is DN80 (located at the bottom), and the nominal diameter of the oil phase outlet is DN100 (located on the upper side wall, 0.3 m from the top). It has an internal arc-shaped guide baffle (thickness of 5 mm).

[0045] The outward-moving guide section has a helical blade with a pitch of 35 mm (small pitch), a length of 0.4 m, a helix angle of 30°, and a flow channel width of 90 mm.

[0046] The external coalescing section has a helical blade with a pitch of 55 mm (medium pitch), a length of 0.6 m, a helix angle of 30°, and a flow channel width of 90 mm.

[0047] The helical blades of the stable separation section have a pitch of 85 mm (large pitch), a length of 0.6 m, a helix angle of 30°, and a flow channel width of 90 mm.

[0048] Operating parameters:

[0049] Processing capacity: 5 m³ / h

[0050] Electric field parameters: A high voltage signal is applied to the inner electrode, the outer electrode is grounded, the average electric field strength in the flow channel is 2.5 kV / cm, and the power frequency sinusoidal voltage waveform is used.

[0051] Operating temperature: 45 ℃ (the conventional heating temperature for crude oil produced fluids, requiring no additional heating and reducing energy consumption)

[0052] Operating pressure: 0.6 MPa (system working pressure, meeting pipeline transportation requirements)

[0053] Industrial treatment effect:

[0054] Aqueous phase removal rate: 98% (inlet water content 25%, oil phase water content after treatment is less than 0.5%), far exceeding the industry standard of 95% removal rate for conventional electric dehydrators.

[0055] Separation stability: After 720 hours of continuous operation, no electric field decay or electric field collapse was observed.

[0056] Export targets: Oil phase export: water content ≤0.5%, meeting the national standard of ≤1% water content for crude oil export.

Claims

1. A coaxial cylindrical electrode variable pitch spiral flow channel electrostatic coalescence device, characterized in that, The device, from top to bottom, includes a feeding section, an electrostatic coalescence section, and a separation section; In the aforementioned feeding section, the outer shell of the feeding section is cylindrical, with an emulsion inlet on the side wall of the outer shell, and the top cover is a sealed flange with an exhaust port. An internal electrode interface is set in the center of the top cover, and the bottom is connected to the electrostatic coalescence section through the flange. The electrostatic coalescence section includes an outer electrode with a cylindrical structure. An inner electrode with a cylindrical structure and coaxial with the outer electrode is set at the center of the cylinder of the outer electrode. The upper end of the inner electrode passes through a flange and is connected to the inner electrode interface at the center of the top cover. The high-voltage cable of the high-voltage power supply is connected through the inner electrode interface. An outer electrode interface is provided on the flange at the bottom. The outer electrode is connected to the grounding cable of the high-voltage power supply through the outer electrode interface. Between the inner electrode and the outer electrode, three spiral blades are arranged in sequence along the flow direction of the water-in-oil emulsion. They are the spiral blades of the outward guiding section, the spiral blades of the external field coalescence section, and the spiral blades of the stable coalescence separation section. The pitch of each spiral blade increases sequentially. The separation section is a cavity structure connected to the bottom flange of the electrostatic coalescence section. The lower part of the side wall of the outer shell of the separation section is provided with a water phase outlet, and the upper part of the side wall is provided with an oil phase outlet. A baffle is installed at the oil phase outlet. The outer shell of the feeding section, the outer electrode of the electrostatic coalescence section, and the outer shell of the separation section are coaxial and have the same radial dimensions.

2. The coaxial cylindrical electrode variable pitch spiral flow channel electrostatic coalescence device as claimed in claim 1, characterized in that, The spiral helix angle of the spiral blades in the outward guiding section, the spiral blades in the external field coalescence section, and the spiral blades in the stable coalescence separation section is 15°-45°, and the pitch increases progressively by 30%-50%.

3. The coaxial cylindrical electrode variable pitch spiral flow channel electrostatic coalescence device as claimed in claim 1, characterized in that, The external electrode is made of a conductive material, which is selected from stainless steel, aluminum alloy and titanium alloy.

4. The coaxial cylindrical electrode variable pitch spiral flow channel electrostatic coalescence device as claimed in claim 1, characterized in that, The inner electrode is a solid rod-shaped or hollow tubular structure, made of a conductive metallic material, selected from stainless steel, carbon steel, aluminum alloy, and titanium alloy.

5. The coaxial cylindrical electrode variable pitch spiral flow channel electrostatic coalescence device as claimed in claim 1, characterized in that, The inner wall of the external electrode is coated with an oil-resistant coating, and the coating material is selected from one of aluminum nitride-fluorocarbon composite and epoxy resin-polyethylene methylamine-titanium oxide.

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