An electric field coalescence cross-flow demulsification device for oily wastewater

Abstract

The present invention discloses an electric field coalescence cross-flow demulsification device for oily wastewater. The device comprises a demulsification power supply equipped with a power controller and a reactor housing equipped with demulsification electrodes A and B. The fluid flow channels of demulsification electrodes A and B, installed in the reactor housing, are staggered by filling with a polymer organic coalescence fabric. Demulsification electrodes A and B are connected in parallel to anode and cathode electrode terminals, which are electrically connected to the positive and negative electrodes of the demulsification power supply outside the reactor housing, respectively. The oily wastewater is pumped into the reactor housing through the water inlet and discharged through the water outlet by a water pump. The residence time of the oily wastewater in the reactor housing is controlled by controlling the pump's displacement. The voltage, pulse frequency, and duty cycle of the output power supply are controlled by the power controller. The present invention can effectively demulsify emulsified oil droplets in water without the addition of chemicals and has a compact structure.

Description

Technical Field

[0001] The present invention mainly relates to the field of equipment for treating oily wastewater in the petroleum industry, and in particular to an electric field coalescence and cross-flow demulsification device for oily wastewater. Background Art

[0002] In recent years, as major domestic and international oil fields have gradually entered the middle and late stages of high-water-cut development, enhanced oil recovery (EOR) and fracturing and acidizing technologies, represented by chemical flooding such as polymer flooding and ternary composite flooding, have been widely used. This has made the composition of oilfield produced water more complex, increased the strength of the interfacial film on the surface of oil particles, and coated the surface of oil particles with surfactant molecules, making it difficult for oil particles to coalesce and increase the difficulty of oil-water separation. In order to treat highly emulsified oily wastewater in a targeted manner, technicians have tried using methods or means such as chemical demulsification, biological demulsification, membrane separation, microwave, ultrasound, and graphene. Although some results have been achieved, they all have their own shortcomings and deficiencies in terms of cost input, operating expenses, equipment compactness, and the presence of secondary pollution and by-products. There is still a considerable gap between them and the increasingly stringent requirements of oilfield on-site engineering applications. Therefore, it is urgent to strengthen the research on oily wastewater demulsification technology and develop efficient oilfield produced water demulsification and oil removal equipment.

[0003] In recent years, scholars both domestically and internationally have reported on the ability of external electric fields to drive collisions between oil droplets, breaking through the interfacial energy barrier between them, thereby promoting collisional coalescence and enhancing the separation of emulsified oil droplets from oily wastewater. Furthermore, when a soluble metal such as iron or aluminum is used as the anode, the external electric field dissolves and oxidizes the anode metal, generating iron and aluminum cations. These cations, through coagulation, form flocs, promoting oil droplet coalescence. Simultaneously, hydrogen bubbles are generated at the cathode, binding to the flocs and causing them to float, promoting oil-water separation. Due to its wide range of applications, effective treatment results, low sludge production, and simple and convenient operation, external electric field demulsification technology has garnered widespread attention in the industry. Research and application results have demonstrated that electric field demulsification technology is a green and efficient technology for the treatment of highly emulsified oily wastewater.

[0004] Publication No. CN113307337A discloses an oil-in-water emulsion demulsification and separation device using an electric field coupled to a conductive particle bed. The device comprises three internal components: buffering, demulsification, and separation. The conductive particle bed and columnar electrodes form a non-uniformly distributed electric field within the bed voids. This coupled electric field's electrophoresis, polarization, and coalescence, coupled with the particle bed's capture, extrusion, adsorption, and filtration, further enhances the mutual contact and movement between oil droplets and the electric field's coalescence of oil droplets. This drives the oil droplets in the oil-in-water emulsion to quickly and effectively contact, coalesce, and merge into larger droplets, thereby enhancing the electric field's demulsification effect on the oil-in-water emulsion.

[0005] Publication No. CN109847413A discloses a micro-electric field oil-water demulsification method. This invention utilizes a micro-electric field pulse generator to generate a pulsed electric field with a voltage of 0-24V and a frequency of 20Hz-2MHz. The pulsed electric field is then applied to the oil and water, separating the oil and water droplets. The micro-electric field is achieved by alternating anode and cathode plates. These plates are connected to the pulsed electric field generator via wiring terminals and energized to form a number of demulsification micro-electric fields. The oil and water enter the micro-electric field from the bottom up through a perforated support plate. Under the action of the pulsed electric field, the oil and water droplets collide, stretch, and coalesce, causing the dispersed droplets to aggregate and stratify, separating the water and oil phases.

[0006] Publication No. CN112499858A discloses a demulsification device and method using a non-uniform electric field coupled with dielectric coalescence. The device includes a separation chamber with an electrode assembly inside that provides an electric field to force the migration of oil droplets in the emulsion. The electrode assembly is uniformly filled with dielectric coalescence units composed of dielectric particles.

[0007] Highly emulsified oily wastewater, such as produced water from polymer flooding oilfields, features severe oil droplet emulsification and relatively high concentrations of oil contaminants, suspended solids, and hardness. These water quality characteristics make oil droplet coalescence more difficult. Long-term operation of demulsification devices places even higher demands on the electrodes' resistance to fouling and continuous operational stability. Existing technologies still have significant room for improvement in addressing these challenges. Summary of the Invention

[0008] The purpose of the present invention is to provide an electric field coalescence cross-flow demulsification device for oily wastewater, which can effectively achieve the demulsification of highly emulsified oil droplets in oily wastewater, improve the oil-water separation efficiency of highly emulsified oily wastewater, reduce the oil sludge production of chemical demulsification, and reduce the investment and operating costs of oily wastewater treatment.

[0009] The technical solution of the present invention is:

[0010] An electric field coalescence cross-flow demulsification device for oily wastewater comprises a demulsification power supply equipped with a power controller and a reactor shell equipped with demulsification electrodes A and B. A water inlet and a water outlet are provided in the shell wall of the reactor shell. The demulsification electrodes A and B are fixed alternately in the reactor shell, wherein:

[0011] The fluid flow channels in the demulsification electrode A and the demulsification electrode B installed in the reactor shell are staggered by filling with high molecular organic coalescing fabric;

[0012] Demulsification electrode A and demulsification electrode B are connected in parallel on the anode electrode terminal and the cathode electrode terminal, and the anode electrode terminal and the cathode electrode terminal are electrically connected to the positive electrode and the negative electrode of the demulsification power supply outside the reactor shell respectively;

[0013] The anode electrode terminal is provided with an anode metal core, and an anode metal gasket and an anode insulating gasket are installed on the outside of the anode metal core. The anode metal gasket and the anode insulating gasket are alternately filled in the terminal hole in contact with the demulsification electrode A and the demulsification electrode B; the cathode electrode terminal is provided with a cathode metal core, and a cathode metal gasket and a cathode insulating gasket are alternately installed on the outside of the cathode metal core; the cathode insulating gasket and the cathode metal gasket are respectively filled in the terminal hole in contact with the demulsification electrode A and the demulsification electrode B correspondingly.

[0014] Preferably, the demulsification electrodes A and B installed in the reactor shell have the same structure and the same number of installations, and the structure and size of the fluid flow channels therein are also the same. The positions of the fluid flow channels blocked by the polymer organic coalescence fabric in the demulsification electrodes A and the demulsification electrodes B are different, and the positions of the fluid flow channels blocked by the polymer organic coalescence fabric in the demulsification electrodes A and the demulsification electrodes B can be interchanged.

[0015] Preferably, the demulsification electrode A and the demulsification electrode B are both circular plates or square plates that fit the inner wall of the reactor shell, and the demulsification electrode A and the demulsification electrode B are also connected in parallel on the electrode fixing column; the demulsification electrode A and the demulsification electrode B are both made of metal iron or metal aluminum.

[0016] Preferably, the material of the anode metal gasket and the cathode metal gasket is the same as that of the demulsification electrode A and the demulsification electrode B; the anode insulating gasket and the cathode insulating gasket are both made of polytetrafluoroethylene.

[0017] Preferably, the polymer organic coalescence fabric is a mixed fabric of polyethylene, polypropylene and polyester polymer fibers, wherein the content of polyethylene is 30%-50%, the content of polypropylene is 20%-30%, and the content of polyester is 20%-40%.

[0018] Preferably, the demulsification electrode A is provided with an electrode A terminal post hole, an electrode A fixed post hole, an electrode A metal inner plate, an electrode A flow channel and an electrode A metal outer plate, and the electrode A fixed post hole and the electrode A terminal post hole are alternately arranged in the connecting plate between the electrode A metal inner plate and the electrode A metal outer plate; the electrode A flow channel is a fluid flow channel formed by the annular gap between the electrode A metal inner plate and the electrode A metal outer plate, and the polymer organic agglomerated fabric is filled in the electrode A metal inner plate, allowing the oily wastewater to pass through the annular gap between the electrode A metal inner plate and the electrode A metal outer plate; the anode electrode terminal and the cathode electrode terminal respectively pass through the electrode A fixed post holes alternately arranged in the connecting plate.

[0019] Preferably, the demulsification electrode B is provided with an electrode B terminal post hole, an electrode B fixing post hole, an electrode B metal inner plate, an electrode B metal outer plate and an electrode B flow channel, and the electrode B fixing post hole and the electrode B terminal post hole are alternately arranged in the connecting plate between the electrode B metal inner plate and the electrode B metal outer plate; the electrode B flow channel is a fluid flow channel formed by the electrode B metal inner plate, and the polymer organic aggregated fabric is filled in the annular gap between the electrode B metal inner plate and the electrode B metal outer plate, allowing the oily wastewater to pass through the electrode B metal inner plate; the anode electrode terminal and the cathode electrode terminal respectively pass through the electrode B terminal post holes alternately arranged in the connecting plate.

[0020] Preferably, the flow area of ​​the electrode A flow channel is equal to that of the electrode B flow channel, and the flow rate of the oily wastewater passing through the electrode A flow channel or the electrode B flow channel is controlled between 5 mm and 60 mm / s.

[0021] Preferably, the assembly distance between the demulsification electrode A and the demulsification electrode B is set between 20 mm and 40 mm; the electrode fixing column is provided with a fixing column metal core column, a fixing column insulating sleeve and an insulating isolation pad, the lower part of the fixing column metal core column is threadedly connected to the fixed base welded to the bottom of the reactor shell and the top is provided with a fastening nut, the fixing column insulating sleeve is sleeved on the outside of the fixing column metal core column, the insulating isolation pad is installed on the outside of the fixing column insulating sleeve and is supported between the demulsification electrode A and the demulsification electrode B.

[0022] Preferably, the inner diameter of the insulating isolation pad is larger than the outer diameter of the insulating sleeve of the fixed column and is equal to or smaller than the width of the connecting plate. The thickness of the insulating isolation pad supported between the demulsification electrode A and the demulsification electrode B is set between 20 mm and 40 mm. The height of the insulating isolation pad located between the lower part of the metal core column of the fixed column and the demulsification electrode at the lower end is determined according to the design requirements and can be made as a whole or multiple pieces can be stacked. The insulating isolation pads located on the outside of the demulsification electrodes at both ends of the insulating sleeve of the fixed column are bonded or hot-melt to the insulating sleeve of the fixed column. The material of the metal core column of the fixed column is stainless steel or carbon steel, the material of the insulating sleeve of the fixed column is polytetrafluoroethylene, the thickness is set between 2 mm and 5 mm, and the material of the insulating isolation pad is high-density polyethylene.

[0023] Preferably, the demulsification power supply is a pulsed DC power supply, the waveform of the pulsed DC voltage of the demulsification power supply is pulsed DC, the voltage is 10-100V, the pulse frequency is 50-2500Hz, and the duty cycle is 0.2-0.9; the automatic switching program of the positive and negative poles in the demulsification power supply is set by the power controller, and the interval of the switching time of the positive and negative poles of the demulsification power supply is 0.5h-3h.

[0024] Compared with the prior art, the present invention has the following significant effects and advantages:

[0025] First, the demulsification electrode A and the demulsification electrode B in the present invention have novel structures. The demulsification electrode A and the demulsification electrode B are insulated from the demulsification electrode A and the demulsification electrode B by the anode insulating gasket and the cathode insulating gasket in the anode electrode terminal and the cathode electrode terminal, and the demulsification electrode A and the demulsification electrode B are connected by the anode metal gasket 4 and the cathode metal gasket in the anode electrode terminal and the cathode electrode terminal.

[0026] Secondly, this device provides a demulsification device for oily wastewater, in which the fluid flow channels in the demulsification electrode A and the demulsification electrode B are arranged in an interlaced manner. Water flows out from the fluid flow channel of the demulsification electrode A and flows into the fluid flow channel of the demulsification electrode B which is arranged in an interlaced manner with the demulsification electrode A, and flows through them one by one, thereby strengthening the collision and coalescence effect between the oil droplets under the action of the electric field. By utilizing the flushing effect of the water phase on the electrode surface, the scaling problem on the surface of the demulsification electrode plate can be significantly reduced, the continuous and stable working time of the demulsification electrode can be extended, and the maintenance cost of the demulsification device can be reduced.

[0027] Third, the present invention uses polymer organic coalescence fabric to fill the fluid flow channel in the demulsification electrode to obtain a cross-flow effect. In addition to the collision and coalescence effect between oil droplets under the action of the electric field, it can also exert the wetting and coalescence and collision and coalescence effects between the oil droplets and the polymer organic coalescence fabric, further improving the coalescence and demulsification efficiency of the device.

[0028] Fourthly, the present invention provides the optimal process parameter conditions for the demulsification device, which can further save costs and improve processing efficiency.

[0029] Refer to the oily wastewater demulsification experiment below. Compared with traditional electric field demulsification and chemical demulsification equipment, the present invention can effectively demulsify emulsified oil droplets in water without adding chemical agents. It has the characteristics of high coagulation and demulsification efficiency, low operating energy consumption, compact structure, space saving, and simple operation and maintenance. It is a green, efficient, and environmentally friendly oily wastewater demulsification equipment with significant use effects. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0031] Figure 1 It is a structural schematic diagram of the present invention.

[0032] Figure 2 Schematic diagram of the structure of the circular plate demulsification electrode A of the present invention.

[0033] Figure 3 Schematic diagram of the structure of the circular plate demulsification electrode B of the present invention.

[0034] Figure 4Cross-sectional view of the anode electrode terminal where different gaskets are installed.

[0035] Figure 5 Cross-sectional view of the cathode electrode terminal where different gaskets are installed.

[0036] Figure 6 This is a cross-sectional view of the schematic structural diagram of the electrode fixing column.

[0037] Figure 7 Schematic diagram of the structure of demulsification electrode A and demulsification electrode B with square plates.

[0038] Figure 1 Middle: reactor shell 1, demulsification electrode A2, demulsification electrode B3, anode electrode terminal 4, electrode fixing column 5, water inlet 6, water outlet 7, cathode electrode terminal 8, polymer organic coalesced fabric 9, demulsification power supply 10, power supply controller 11.

[0039] Figure 2 Middle: electrode A terminal hole 2-1, electrode A fixing column hole 2-2, electrode A metal inner plate 2-3, electrode A flow channel 2-4, electrode A metal outer plate 2-5.

[0040] Figure 3 Middle: electrode B terminal hole 3-1, electrode B fixing column hole 3-2, electrode B metal inner plate 3-3, electrode B metal outer plate 3-4, electrode B flow channel 3-5.

[0041] Figure 4 Middle: anode electrode terminal metal core 4-1, anode metal gasket 4-2-1, anode insulating gasket 4-2-2.

[0042] Figure 5 Middle: cathode electrode terminal metal core 8-1, cathode metal gasket 8-2-1, cathode insulating gasket 8-2-2.

[0043] Figure 6 Middle: fixed column metal core column 5-1, fixed column insulating sleeve 5-2. DETAILED DESCRIPTION

[0044] The accompanying drawings are for reference and illustration purposes only and are not intended to limit the scope of protection of the present invention. The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0045] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0046] In the description of the present invention, it should be understood that the terms "length," "width," "up," "down," "front," "back," "left," "right," "vertical," "horizontal," "top," "bottom," "inside," "outside," and the like, indicating positions or location relationships, are based on the positions or location relationships shown in the accompanying drawings and are intended only to facilitate the description of the present invention and simplify the description. They do not indicate or imply that the devices or elements referred to must have a specific orientation, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limiting the present invention. Furthermore, in the description of the present invention, "plurality" means two or more, unless otherwise expressly and specifically defined.

[0047] The following is a detailed description of the embodiments of the present invention with reference to the accompanying drawings.

[0048] See also Figure 1 - Figure 7 An electric field coalescence cross-flow demulsification device for oily wastewater includes a demulsification power supply 10 equipped with a power controller 11 and a reactor shell 1 equipped with demulsification electrodes A2 and B3. A water inlet 6 and a water outlet 7 are provided in the shell wall of the reactor shell 1. The demulsification electrodes A2 and B3 are staggered and fixed in the reactor shell 1, wherein:

[0049] The fluid flow channels in the demulsification electrodes A2 and B3 installed in the reactor shell 1 are staggered by filling the polymer organic coalescing fabric 9;

[0050] The demulsification electrode A2 and the demulsification electrode B3 are connected in parallel to the anode electrode terminal 4 and the cathode electrode terminal 8, and the anode electrode terminal 4 and the cathode electrode terminal 8 are electrically connected to the positive and negative electrodes of the demulsification power supply 10 outside the reactor shell 1 respectively;

[0051] The anode electrode terminal 4 is provided with an anode metal core 4-1, and an anode metal gasket 4-2-1 and an anode insulating gasket 4-2-2 are installed on the outside of the anode metal core 4-1. The anode metal gasket 4-2-1 and the anode insulating gasket 4-2-2 are alternately filled in the terminal hole in contact with the demulsification electrode A2 and the demulsification electrode B3; the cathode electrode terminal 8 is provided with a cathode metal core 8-1, and a cathode metal gasket 8-2-1 and a cathode insulating gasket 8-2-2 are alternately installed on the outside of the cathode metal core 8-1; the cathode insulating gasket 8-2-2 and the cathode metal gasket 8-2-1 are respectively filled in the terminal hole in contact with the demulsification electrode A2 and the demulsification electrode B3 correspondingly.

[0052] The oily wastewater is pumped into the water inlet 6 by a water pump and discharged through the water outlet 7. The residence time of the oily wastewater in the reactor shell 1 is controlled by controlling the displacement of the water pump; the voltage, pulse frequency and duty cycle of the output power supply are controlled by the power controller 11.

[0053] The demulsification power supply 10 enables the device of the present invention to operate under optimal operating conditions, ensuring efficient collision and coalescence of emulsified oil droplets in wastewater while minimizing power consumption, extending the service life of demulsification electrodes A2 and B3, and ensuring long-term, efficient, and stable operation of the device of the present invention. The demulsification power supply 10 is commercially available.

[0054] The interior of the reactor shell 1 undergoes an anti-corrosion surface treatment to ensure long-term operation. The anti-corrosion layer also insulates the demulsification electrodes A2 and B3 from the metal shell of the reactor shell 1. Demulsification electrodes A2 and B3 are staggered and filled with a polymeric organic coalescing fabric 9, creating a structure that allows cross-flow of water within the demulsification device, enhancing the collision and coalescence of oil droplets under the action of the electric field.

[0055] like Figure 1 、 Figure 4 and Figure 5 As shown, when the demulsification power supply 10 is connected to the device, the cathode electrode terminal 8 turns all demulsification electrodes filled with the cathode metal gasket 8-2-1 into negative electrodes, and the anode electrode terminal 4 turns all demulsification electrodes filled with the anode metal gasket 4-2-1 into positive electrodes. All demulsification electrodes equipped with the anode insulating gasket 4-2-2 are insulated from the anode electrode terminal 4, and all demulsification electrodes equipped with the cathode insulating gasket 8-2-2 are insulated from the cathode electrode terminal 8. The anode electrode terminal 4 and the cathode electrode terminal 8 are connected to the positive and negative electrodes of the demulsification power supply 10, respectively, transmitting the electric field of the demulsification power supply 10 to demulsification electrodes A2 and B3.

[0056] During normal operation of the present device, oily wastewater is pumped in through water inlet 6 and then flows sequentially through the fluid channels within demulsification electrodes A2 and B3, connecting the external pulsed DC electric field of the demulsification power supply 10 to these electrodes. Under the action of the electric field, oil droplets in the oily wastewater collide and coalesce, creating conditions for the efficient separation of emulsified oil droplets from the wastewater. The present device has a simple structure, and the staggered fluid channels within demulsification electrodes A2 and B3 significantly enhance the demulsification of oily wastewater.

[0057] Based on the above embodiment 1, the present invention also has the following embodiment

[0058] In a preferred embodiment, the demulsification electrodes A2 and B3 installed in the reactor shell 1 have the same structure and number of components, and their fluid flow passages have the same structure and dimensions. The locations of the fluid flow passages blocked by the polymer organic agglomerated fabric 9 in the demulsification electrodes A2 and B3 are different, and the locations of the fluid flow passages blocked by the polymer organic agglomerated fabric 9 in the demulsification electrodes A2 and B3 are interchangeable. This allows oily wastewater entering the reactor shell 1 through the water inlet 6 to cross-flow through the fluid flow passages in the demulsification electrodes A2 and B3 before exiting through the water outlet 7.

[0059] A preferred embodiment: the demulsification electrode A2 and the demulsification electrode B3 are both circular plates or square plates that fit the inner wall of the reactor shell 1. The demulsification electrode A2 and the demulsification electrode B3 are also connected in parallel to the electrode fixing column 5 to fix and support the demulsification electrode A2 and the demulsification electrode B3. The demulsification electrode A2 and the demulsification electrode B3 are both made of metal iron or metal aluminum.

[0060] In a preferred embodiment, the material of the anode metal gasket 4-2-1 and the cathode metal gasket 8-2-1 is the same as that of the demulsification electrode A2 and the demulsification electrode B3; the anode insulating gasket 4-2-2 and the cathode insulating gasket 8-2-2 are both made of polytetrafluoroethylene.

[0061] A preferred embodiment: the polymer organic coalescence fabric 9 is a mixed fabric of polyethylene, polypropylene and polyester polymer fibers, wherein the polyethylene content is 30%-50%, the polypropylene content is 20%-30%, and the polyester content is 20%-40%, and the demulsification effect is good.

[0062] The following uses a circular plate as an example to illustrate the structures of demulsification electrodes A2 and B3:

[0063] A preferred embodiment: the demulsification electrode A2 is provided with an electrode A terminal hole 2-1, an electrode A fixed column hole 2-2, an electrode A metal inner plate 2-3, an electrode A flow channel 2-4 and an electrode A metal outer plate 2-5, and the electrode A fixed column hole 2-2 and the electrode A terminal hole 2-1 are alternately arranged in the connecting plate between the electrode A metal inner plate 2-3 and the electrode A metal outer plate 2-5; the electrode A flow channel 2-4 is a fluid flow channel formed by the annular gap between the electrode A metal inner plate 2-3 and the electrode A metal outer plate 2-5, and the polymer organic aggregated fabric 9 is filled in the electrode A metal inner plate 2-3, allowing the oily wastewater to pass through the annular gap between the electrode A metal inner plate 2-3 and the electrode A metal outer plate 2-5; the anode electrode terminal 4 and the cathode electrode terminal 8 respectively pass through the electrode A fixed column hole 2-1 alternately arranged in the connecting plate.

[0064] A preferred embodiment: the demulsification electrode B3 is provided with an electrode B terminal post hole 3-1, an electrode B fixed post hole 3-2, an electrode B metal inner plate 3-3, an electrode B metal outer plate 3-4 and an electrode B flow channel 3-5, the electrode B fixed post hole 3-2 and the electrode B terminal post hole 3-1 are alternately arranged in the connecting plate between the electrode B metal inner plate 3-3 and the electrode B metal outer plate 3-4; the electrode B flow channel 3-5 is a fluid flow channel formed by the electrode B metal inner plate 3-3, the polymer organic aggregated fabric 9 is filled in the annular gap between the electrode B metal inner plate 3-3 and the electrode B metal outer plate 3-4, allowing oily wastewater to pass through the electrode B metal inner plate 3-3; the anode electrode terminal 4 and the cathode electrode terminal 8 respectively pass through the electrode B terminal post holes 3-1 alternately arranged in the connecting plate.

[0065] A preferred embodiment: the flow areas of the electrode A flow channel 2-4 and the electrode B flow channel 3-5 are equal, and the flow rate of the oily wastewater passing through the electrode A flow channel 2-4 or the electrode B flow channel 3-5 is controlled between 5mm-60mm / s.

[0066] In a preferred embodiment, the assembly distance between the demulsification electrodes A2 and B3 is set between 20 mm and 40 mm. The electrode fixing column 5 comprises a fixing column metal core 5-1, a fixing column insulating sleeve 5-2, and an insulating spacer 5-3. The lower portion of the fixing column metal core 5-1 is threadedly connected to a fixing base 12 welded to the bottom of the reactor shell 1, and a fastening nut is installed on the top. The fixing column insulating sleeve 5-2 is inserted into the outer surface of the fixing column metal core 5-1. The insulating spacer 5-3 is installed outside the fixing column insulating sleeve 5-2 and is supported between the demulsification electrodes A2 and B3 to support and fix the demulsification electrodes. All demulsification electrodes are fixed as a whole by the fixing column metal core 5-1, the fixing column insulating sleeve 5-2, and the anode electrode terminal 4 and the cathode electrode terminal 8.

[0067] In a preferred embodiment, the inner diameter of the insulating spacer 5-3 is greater than the outer diameter of the insulating sleeve 5-2 of the fixed column and equal to or less than the width of the connecting plate. The thickness of the insulating spacer 5-3 between the demulsification electrode A2 and the demulsification electrode B3 is set between 20mm and 40mm. The height of the insulating spacer 5-3 between the lower portion of the fixed column metal core 5-1 and the lowest demulsification electrode is determined according to design requirements and can be manufactured as a whole or multiple pieces can be stacked. The insulating spacer 5-3 outside the demulsification electrodes at both ends of the insulating sleeve 5-2 of the fixed column are bonded or hot-fused to the insulating sleeve 5-2 of the fixed column. The metal core 5-1 of the fixed column is made of stainless steel or carbon steel, the insulating sleeve 5-2 of the fixed column is made of polytetrafluoroethylene with a thickness set between 2mm and 5mm, and the insulating spacer 5-3 is made of high-density polyethylene. The insulating sleeve 5-2 is insulated from the electrode fixing column 5, so the electrode fixing column 5 is not electrically charged and only serves to fix it.

[0068] A preferred embodiment: the demulsification power supply 10 is a pulsed DC power supply, the waveform of the pulsed DC voltage of the demulsification power supply 10 is pulsed DC, the voltage is 10-100V, the pulse frequency is 50-2500Hz, and the duty cycle is 0.2-0.9; the automatic switching program of the positive and negative poles in the demulsification power supply 10 is set by the power controller 11, and the interval of the switching time of the positive and negative poles of the demulsification power supply 10 is 0.5h-3h.

[0069] The present invention has carried out the oily wastewater demulsification experiment and obtained the following experimental data

[0070] Experimental methods and experimental data

[0071] 50 grams of #10 white oil was added to 50 liters of ultrapure water, and a 6-7‰ NaCl solution was added. The oil-water mixture was then sheared at 10,000 rpm for 15 minutes using a high-speed shearing machine to remove the floating oil. The resulting highly emulsified oily wastewater had water quality indicators shown in Table 1.

[0072] Table 1 Water quality indicators of oily wastewater

[0073] Water quality indicators Petroleum (mg / L) Turbidity (NUT) Oily wastewater 650 523

[0074] The cross-flow orifice plate electric field coalescing demulsifier of the present invention was used to demulsify highly emulsified oily wastewater. The operating conditions were: demulsification electrodes A2 and B3 were made of aluminum, with a spacing of 25 mm between electrodes A2 and B3; a hydraulic retention time of 2 minutes, an operating voltage of 20 V, a frequency of 2000 Hz, and a duty cycle of 50%. After 10 minutes of continuous operation, the treated effluent was collected and allowed to settle naturally for 30 minutes before the water quality of the subsurface aqueous phase was measured. The treated effluent quality is shown in Table 2.

[0075] Table 2 Water quality parameters of treated effluent

[0076] Water quality indicators Petroleum (mg / L) Turbidity (NUT) Oily wastewater 55-80 10-30

[0077] As can be seen from Table 2, after treatment with the present invention, the oil-water separation process of highly emulsified oily wastewater can be accelerated, and the emulsified oil concentration in the aqueous phase is significantly reduced, reflecting that the device of the present invention has a high demulsification efficiency for oily wastewater and has broad prospects in the field of demulsification of oily wastewater such as oilfield produced water.

[0078] Experimental methods and experimental data 2

[0079] The experimental wastewater was the effluent from an oilfield tertiary oil recovery oily wastewater treatment station. The water sample contained approximately 730 mg / L of petroleum compounds and a pH of 7.4. The wastewater had a complex composition, containing high concentrations of polyacrylamide polymers, ammonia nitrogen, and numerous difficult-to-degrade organic pollutants. The oil droplets in the water were stable and highly emulsified, making separation difficult using conventional natural sedimentation.

[0080] The present invention was used to treat the effluent from the aforementioned tertiary oil recovery oily wastewater treatment station. A 40-liter water sample was collected on-site for testing. The device's operating parameters were set as follows: a hydraulic retention time of 3 minutes, a 30mm spacing between demulsification electrodes A2 and B3, a voltage of 25V, a frequency of 2000Hz, and a duty cycle of 50%. After 10 minutes of operation, the treated effluent was collected and allowed to settle naturally for 30 minutes. The water quality indicators of the subsurface aqueous phase were measured. The average oil removal rate in the effluent reached 92%, demonstrating significant demulsification and oil removal effectiveness.

[0081] Experimental methods and experimental data 3

[0082] The water sample used in the experiment came from a wastewater treatment plant at an oil refinery. The wastewater primarily contained pollutants such as petroleum, recalcitrant organic matter, and ammonia nitrogen. A 20-liter water sample was collected on-site for testing. The specific water quality indicators are shown in Table 3.

[0083] Table 3 Raw water quality indicators

[0084] Water quality indicators Numerical Petroleum (mg / L) 355 COD (mg / L) 750 pH 7.42 Ammonia nitrogen (mg / L) 53

[0085] The experimental operating parameters of the device were set as follows: a hydraulic retention time of 5 minutes, a spacing of 25 mm between demulsification electrodes A2 and B3, and electric field parameters of 30 V, 3000 Hz, and a duty cycle of 40%. The measured removal rates of petroleum, COD, and ammonia nitrogen during operation reached 92%, 62%, and 45%, respectively.

[0086] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present invention should be included in the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection of the claims.

Claims

1. An electric field coalescence cross-flow demulsification device for oily wastewater, comprising a demulsification power supply (10) equipped with a power controller (11) and a reactor shell (1) equipped with demulsification electrodes A (2) and demulsification electrodes B (3), a water inlet (6) and a water outlet (7) being provided in the shell wall of the reactor shell (1), and the demulsification electrodes A (2) and the demulsification electrodes B (3) being staggered and fixed in the reactor shell (1), wherein: The fluid flow channels of the demulsification electrodes A (2) and the demulsification electrodes B (3) installed in the reactor shell (1) are staggered by filling the polymer organic aggregate fabric (9); the demulsification electrodes A (2) and the demulsification electrodes B (3) are connected in parallel on the anode electrode terminal (4) and the cathode electrode terminal (8), and the anode electrode terminal (4) and the cathode electrode terminal (8) are respectively electrically connected to the positive electrode and the negative electrode of the demulsification power supply (10) outside the reactor shell (1); the anode electrode terminal (4) is provided with an anode metal core column (4-1), and an anode metal gasket (4-2-1) and an anode insulating gasket (4-2-2) are installed outside the anode metal core column (4-1), and the anode metal gasket (4-2-1) and the anode insulating gasket (4-2-2) are alternately filled in the demulsification electrodes. The cathode electrode terminal (8) is provided with a cathode metal core column (8-1), and the cathode metal core column (8-1) is alternately provided with a cathode metal gasket (8-2-1) and a cathode insulating gasket (8-2-2); the cathode insulating gasket (8-2-2) and the cathode metal gasket (8-2-1) are respectively filled in the terminal hole contacting the demulsification electrode A (2) and the demulsification electrode B (3) correspondingly to the anode metal gasket (4-2-1) and the anode insulating gasket (4-2-2); the demulsification power supply (10) is a pulsed DC power supply, and the automatic switching program of the positive and negative poles in the demulsification power supply (10) is set by the power supply controller (11), and the interval of the positive and negative pole switching time of the demulsification power supply (10) is 0.5h-3h.

2. The electric field coalescence cross-flow demulsification device for oily wastewater according to claim 1, characterized in that: The demulsification electrodes A (2) and the demulsification electrodes B (3) installed in the reactor shell (1) have the same structure and the same number of installations, and the structure and size of the fluid flow channels therein are also the same. The positions of the fluid flow channels blocked by the polymer organic agglomerate fabric (9) in the demulsification electrodes A (2) and the demulsification electrodes B (3) are different, and the positions of the fluid flow channels blocked by the polymer organic agglomerate fabric (9) in the demulsification electrodes A (2) and the demulsification electrodes B (3) can be interchanged.

3. The electric field coalescence cross-flow demulsification device for oily wastewater according to claim 1 or 2, characterized in that: The demulsification electrode A (2) and the demulsification electrode B (3) are both circular plates or square plates that fit the inner wall of the reactor shell (1). The demulsification electrode A (2) and the demulsification electrode B (3) are also connected in parallel to the electrode fixing column (5). The demulsification electrode A (2) and the demulsification electrode B (3) are both made of metal iron or metal aluminum.

4. The electric field coalescence cross-flow demulsification device for oily wastewater according to claim 3, characterized in that: The material of the anode metal gasket (4-2-1) and the cathode metal gasket (8-2-1) is the same as that of the demulsification electrode A (2) and the demulsification electrode B (3); the anode insulating gasket (4-2-2) and the cathode insulating gasket (8-2-2) are both made of polytetrafluoroethylene.

5. The electric field coalescence cross-flow demulsification device for oily wastewater according to claim 4, characterized in that: The polymer organic coalescence fabric (9) is a mixed fabric of polyethylene, polypropylene and polyester polymer fibers, wherein the content of polyethylene is 30%-50%, the content of polypropylene is 20%-30%, and the content of polyester is 20%-40%.

6. The electric field coalescence cross-flow demulsification device for oily wastewater according to claim 5, characterized in that: The demulsification electrode A (2) is provided with an electrode A terminal hole (2-1), an electrode A fixed column hole (2-2), an electrode A metal inner plate (2-3), an electrode A flow channel (2-4) and an electrode A metal outer plate (2-5). The electrode A fixed column hole (2-2) and the electrode A terminal hole (2-1) are alternately arranged in the connecting plate between the electrode A metal inner plate (2-3) and the electrode A metal outer plate (2-5); the electrode A flow channel (2-4) is a fluid flow channel formed by the annular gap between the electrode A metal inner plate (2-3) and the electrode A metal outer plate (2-5); the polymer organic aggregated fabric (9) is filled in the electrode A metal inner plate (2-3) to allow oily wastewater to pass through the annular gap between the electrode A metal inner plate (2-3) and the electrode A metal outer plate (2-5); the anode electrode terminal (4) and the cathode electrode terminal (8) respectively pass through the electrode A terminal hole (2-1) alternately arranged in the connecting plate.

7. The electric field coalescence cross-flow demulsification device for oily wastewater according to claim 6, characterized in that: The demulsification electrode B (3) is provided with an electrode B terminal post hole (3-1), an electrode B fixed post hole (3-2), an electrode B metal inner plate (3-3), an electrode B metal outer plate (3-4) and an electrode B flow channel (3-5). The electrode B fixed post hole (3-2) and the electrode B terminal post hole (3-1) are alternately arranged in the connecting plate between the electrode B metal inner plate (3-3) and the electrode B metal outer plate (3-4); the electrode B flow channel (3-5) is a fluid flow channel formed by the electrode B metal inner plate (3-3); the polymer organic aggregated fabric (9) is filled in the annular gap between the electrode B metal inner plate (3-3) and the electrode B metal outer plate (3-4), allowing the oily wastewater to pass through the electrode B metal inner plate (3-3); the anode electrode terminal post (4) and the cathode electrode terminal post (8) respectively pass through the electrode B terminal post hole (3-1) alternately arranged in the connecting plate.

8. The electric field coalescence cross-flow demulsification device for oily wastewater according to claim 7, characterized in that: The flow areas of the electrode A flow channel (2-4) and the electrode B flow channel (3-5) are equal, and the flow rate of the oily wastewater passing through the electrode A flow channel (2-4) or the electrode B flow channel (3-5) is controlled between 5 mm and 60 mm / s.

9. The electric field coalescence cross-flow demulsification device for oily wastewater according to claim 3, characterized in that: The assembly distance between the demulsification electrode A (2) and the demulsification electrode B (3) is set between 20 mm and 40 mm; the electrode fixing column (5) is provided with a fixing column metal core column (5-1), a fixing column insulating sleeve (5-2) and an insulating isolation pad (5-3); the lower part of the fixing column metal core column (5-1) is threadedly connected to a fixing base (12) welded to the bottom of the reactor shell (1) and a fastening nut is installed on the top; the fixing column insulating sleeve (5-2) is inserted into the outside of the fixing column metal core column (5-1); the insulating isolation pad (5-3) is installed on the outside of the fixing column insulating sleeve (5-2) and is supported between the demulsification electrode A (2) and the demulsification electrode B (3).

10. The electric field coalescence cross-flow demulsification device for oily wastewater according to claim 9, characterized in that: The inner diameter of the insulating isolation pad (5-3) is larger than the outer diameter of the fixed column insulating sleeve (5-2) and is equal to or smaller than the width of the connecting plate. The thickness of the insulating isolation pad (5-3) supported between the demulsification electrode A (2) and the demulsification electrode B (3) is set between 20 mm and 40 mm. The height of the insulating isolation pad (5-3) located between the lower part of the fixed column metal core (5-1) and the demulsification electrode at the lower end is determined according to design requirements and can be made as a whole or multiple pieces can be stacked. The insulating isolation pads (5-3) located outside the demulsification electrodes at both ends of the fixed column insulating sleeve (5-2) are bonded or hot-melted to the fixed column insulating sleeve (5-2). The material of the fixed column metal core (5-1) is stainless steel or carbon steel, the material of the fixed column insulating sleeve (5-2) is polytetrafluoroethylene, the thickness is set between 2 mm and 5 mm, and the material of the insulating isolation pad (5-3) is high-density polyethylene.

11. The electric field coalescence cross-flow demulsification device for oily wastewater according to claim 1, characterized in that: The waveform of the pulsed DC voltage of the demulsification power supply (10) is pulsed DC, the voltage is 10-100V, the pulse frequency is 50-2500 Hz, and the duty cycle is 0.2-0.9.

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