A demulsification separation system and method for an oil-water emulsion

Abstract

The present invention relates to a demulsification and separation system and method for oil-water emulsions. The system includes a three-stage demulsifier, a microwave and ultrasonic generator, a connecting elbow, a riser pipe, a primary hydrocyclone separator, a secondary hydrocyclone separator, a reflux pump, an oil-rich storage tank, a conditioning agent feeding port, a screw feeder, a blanking pipe, etc. Through the demulsification and heating effects of microwaves and ultrasonic waves, the design of the three-stage structure type of the demulsifier, the fluid rotation motion mode, the circulating flow and utilization of the oil-containing reflux liquid, and the addition and use of the conditioner, the efficient demulsification and separation of oil and water are realized, enabling the efficient recovery of oil products. The liquid-solid mixture is separated by the hydrocyclone separator and enters the subsequent process. The oil-containing reflux liquid is recycled, reducing the oil entrainment in the liquid-solid mixture and improving the oil recovery efficiency and oil product quality.

Description

Technical Field

[0001] The present invention relates to a demulsification separation system and method for an oil-water emulsion, and particularly to a demulsification separation system and method for water-containing oil sludge, oil residue or oil-containing wastewater based on a fluidized bed. Background Art

[0002] With the continuous development of China's economy and the increasing population, the discharge of domestic sewage and industrial wastewater is increasing day by day. According to statistics, the national wastewater discharge in 2017 was about 77.1 billion tons, of which the industrial wastewater discharge was about 18.16 billion tons, accounting for 23.55%; there were 4,063 sewage treatment plants built and operated in urban areas across the country, and the daily urban sewage treatment capacity was 170 million cubic meters; the domestic sludge production in 2017 was 50 million tons, and the industrial sludge production was about 40 million tons. Due to the process and specific unit operations in industries such as crude oil, refining, and chemical engineering, sewage often contains a large amount of oil, or waste such as floating slag, residue, bottom slag, and oil sludge with a high oil content also contains a large amount of water. Achieving oil-water separation is an inevitable measure to recover oil products and resources and reduce environmental pollution; traditional processes have problems such as low separation efficiency, high energy consumption, large investment, large floor area, or serious secondary pollution. There is an urgent need for a technology with a compact structure, cleanliness, and high efficiency to treat and dispose of water-containing oil sludge, oil residue, or oil-containing sewage to protect the ecological environment, reduce pollution, and improve the comprehensive economic, social, and environmental benefits of enterprises.

[0003] Based on the demulsification separation of oil-containing sewage treatment and emulsions such as water-containing oil sludge and oil residue, the present invention makes full use of the characteristics of good liquid-solid mixing, fast heat and mass transfer, uniform temperature, and compact structure of the three-stage structure type and the riser pipe, the advantages of promoting the aggregation and growth of oil droplets by microwaves and ultrasonic waves, and the demulsification function of conditioning agents, breaks through the technical bottlenecks of the recycling of oil-containing reflux liquid, the combination of liquid-solid flow and rotational motion, and the combination of microwave / ultrasonic treatment and hydrodynamic structure design, realizes efficient oil-water separation, and improves the oil recovery efficiency and oil quality. Summary of the Invention

[0004] One object of the present invention is to develop a demulsification separation system and method for an oil-water emulsion, and particularly to a demulsification separation system and method for water-containing oil sludge, oil residue or oil-containing wastewater based on a fluidized bed; the second object is to further improve the efficiency of oil-water separation and the oil quality.

[0005] The technical solution for achieving the purpose of the present invention is as follows: A demulsification and separation system for an oil-water emulsion, comprising a water-containing oil sludge feeding unit, a three-stage demulsifier, a microwave generator, an ultrasonic generator, a connecting elbow, a riser pipe, a first-stage hydrocyclone separator, a second-stage hydrocyclone separator, a reflux pump, a rich oil storage tank, a conditioning agent feeding port, a screw feeder, and a discharging pipe, which are connected in sequence. The system separates a rich oil product and a water-solid mixture. The three-stage demulsifier adopts a structural design for recycling the oil-containing reflux liquid, so that the oil-containing reflux liquid separated by the first-stage hydrocyclone separator and the second-stage hydrocyclone separator is recycled to the three-stage demulsifier; the three-stage demulsifier can be provided with a microwave generator and an ultrasonic generator, so that the three-stage demulsifier adopts a demulsification method combining the recycling of the oil-containing reflux liquid, microwave, and ultrasonic wave.

[0006] For the above-mentioned demulsification and separation system for an oil-water emulsion, the conditioning agent feeding system comprises a conditioning agent feeding port, a screw feeder, and a discharging pipe; the three-stage demulsifier comprises an intermediate section, a settling section, and a conical section. The three-stage demulsifier is connected to the conditioning agent feeding system through the discharging pipe. The settling section of the three-stage demulsifier is connected to the rich oil storage tank through a pipeline. The oil product inside the rich oil storage tank is discharged from the bottom, and the non-condensable gas is removed from above it; the water-containing oil sludge feeding unit is connected to the tangential position at the bottom of the intermediate section of the three-stage demulsifier through a pipeline, and makeup water is connected to the tangential position at the bottom of the intermediate section of the three-stage demulsifier through a pipeline; the conical section of the three-stage demulsifier is connected to the riser pipe through a connecting elbow, the riser pipe is connected to the first-stage hydrocyclone separator and the second-stage hydrocyclone separator through pipelines, the second-stage hydrocyclone separator is connected to the reflux pump through a pipeline, and the first-stage hydrocyclone separator and the second-stage hydrocyclone separator are combined into a water-solid mixture through a pipeline. After the separation of water and solid, the water and solid substances can be recycled respectively. The oil-containing reflux liquid from the reflux pump is divided into three paths, namely the oil-containing reflux liquid in the riser pipe, the oil-containing reflux liquid in the connecting elbow, and the oil-containing reflux liquid in the conical section. The oil-containing reflux liquid in the riser pipe enters the riser pipe through a pipeline connection, the oil-containing reflux liquid in the connecting elbow enters the connecting elbow through a pipeline connection, and the oil-containing reflux liquid in the conical section enters the conical section through a pipeline connection.

[0007] For the above-mentioned demulsification and separation system for an oil-water emulsion, the three-stage demulsifier adopts a segmented structure. From bottom to top, the diameter of the reactor gradually increases, the diameter of the intermediate section remains unchanged, and the diameter of the settling section is the largest. A microwave generator or an ultrasonic generator is arranged outside the intermediate section of the three-stage demulsifier, and an ultrasonic generator or a microwave generator is arranged outside the settling section; when microwave irradiation is carried out, the magnetrons are arranged in pairs, and an absorbent is required to be configured inside the three-stage demulsifier. When microwave heating is adopted, the main body shell of the intermediate section is made of ceramic or quartz material.

[0008] For the above-mentioned demulsification and separation system of an oil-water emulsion, the conical section of the three-stage demulsifier is not provided with a gas distribution plate. The oil-containing return liquid in the conical section enters the conical section tangentially from the side of the conical section. The oil-containing return liquid in the connecting elbow enters in a tangential direction at the bottom of the connecting elbow. The oil-containing return liquid in the riser enters the riser vertically upward from the bottom of the riser.

[0009] For the above-mentioned demulsification and separation system of an oil-water emulsion, the feed pipe enters at the top of the settling section of the three-stage demulsifier. The end of the feed pipe is set as a straight pipe, and the opening of the straight pipe is vertically downward. The feed pipe extends to the bottom of the middle section and is located at the radial middle position of the three-stage demulsifier. The bottom surface of the feed pipe is at a position above the vertical direction of the connecting pipe between the water-containing oil sludge feeding unit and the middle section, and is also at a position above the vertical direction of the inlet of the make-up water at the middle section.

[0010] For the above-mentioned demulsification and separation system of an oil-water emulsion, the conditioning agent feeding port includes a rotary valve feeder or a star feeder and a baffle below it. The material in the feed pipe provides a material seal, and an inert gas can be injected into the screw feeder to provide a gas seal. The conditioning agent is a liquid or a solid at normal temperature.

[0011] A demulsification and separation system for an oil-water emulsion according to the present invention. The water-containing oil sludge feeding unit inputs the water-containing oil sludge into the middle section of the three-stage demulsifier and enters the three-stage demulsifier at the tangential position at the bottom of the middle section. The supplementary water enters the three-stage demulsifier at the tangential position at the bottom of the middle section, and forms corresponding tangentially entering fluid streams with the water-containing oil sludge, thereby forming a liquid-solid rotational flow and forming a low-pressure area in the middle of the middle section of the three-stage demulsifier, facilitating the conditioning agent to enter the three-stage demulsifier from the feeding pipe and fully and violently mix with the water-containing oil sludge, promoting oil-water separation and liquid-solid separation; a microwave generator or an ultrasonic generator is arranged outside the middle section of the three-stage demulsifier, which can promote the aggregation and growth of oil droplets and oil-water separation. An ultrasonic generator or a microwave generator is arranged outside the settling section, further promoting the aggregation and growth of oil droplets and oil-water separation. The light oil products float up and overflow from the settling section into the rich oil storage tank. The oil products are discharged from the bottom of the rich oil storage tank, and the non-condensable gas is removed from the top of the rich oil storage tank; the heavier water-solid phase inside the three-stage demulsifier deposits to the bottom of the middle section. The oil-containing return liquid is respectively circulated and returned to the conical section, the connecting elbow and the inlet of the riser by the return pump. The oil-containing return liquid in the conical section enters the conical section at the tangential position on the side of the conical section. The oil-containing return liquid in the connecting elbow enters at the tangential direction at the bottom of the connecting elbow. The oil-containing return liquid in the riser enters the riser vertically upward at the bottom of the riser. The oil-containing return liquid in the conical section further realizes oil-water separation and improves the oil product recovery rate under the action of the rotational flow in the conical section and the conditioning agent. The oil-containing return liquid in the connecting elbow, the oil-containing return liquid in the riser and the supplementary water injected at the bottom of the riser provide power for liquid-solid circulation and liquid-solid lifting; after the liquid-solid in the riser is separated by the first-stage hydrocyclone and the second-stage hydrocyclone, the heavy components sink and are converged into a water-solid mixture through the pipeline. After the separation of water and solid, the water and solid substances can be recycled respectively. The light components are returned to the inlet of the conical section, the connecting elbow and the riser by the return pump; the conditioning agent feeding port includes a rotary valve feeder or a star feeder and a baffle below it, which feeds the liquid or solid conditioning agent into the three-stage demulsifier from the feeding pipe. The material inside the feeding pipe provides a material seal, and an inert gas can be injected inside the screw feeder to provide a gas seal.

[0012] The present invention has the following positive effects: (1) The demulsifier adopts a three-stage structure. From bottom to top, it is a conical section, an intermediate section, and a settling section in sequence, with the diameter gradually increasing. The settling section has the largest diameter, which is beneficial to slowing down the flow rate, reducing water-solid entrainment, prolonging the residence time, and improving the oil-water separation efficiency; (2) There is a violent liquid-solid rotational flow in the conical section, which promotes the liquid-solid mixing of the conditioning agent and the fluid and improves the hydrodynamic distribution of the fluid in the conical section; (3) Microwaves and ultrasonic waves accelerate the aggregation and growth of oil droplets and the oil-water separation, improve the system temperature distribution, enhance the heat and mass transfer efficiency, and improve the oil-water separation efficiency; (4) The circulation reflux of the oil-containing reflux liquid tangentially enters the three-stage demulsifier from the side of the conical section. Under the action of the conditioning agent, microwaves, and ultrasonic waves, the oil continuously aggregates, the oil phase floats upward, and the water and solids sink downward, thereby improving the oil-water separation efficiency; (5) The feeding pipe extends deep into the intermediate section, and the conditioning agent enters the bottom of the intermediate section of the three-stage demulsifier. The liquid rotational flow creates a low-pressure area in the intermediate section, facilitating the smooth addition of the conditioning agent into the three-stage demulsifier and its full mixing with the liquid; (6) The rotary valve feeder or star feeder of the conditioning agent feeding system, the sealing baffle, the material seal of the feeding pipe, and the sealing gas introduced by the screw feeder effectively isolate the conditioning agent feeding system from the three-stage demulsifier, ensuring the reliable and stable operation of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] In order to make the content of the present invention easier to be clearly understood, the following further details the present invention according to specific embodiments in conjunction with the drawings, where

[0014] Figure 1 is a schematic structural diagram of the system of the present invention.

[0015] Wherein

[0016] 1 Three-stage demulsifier, 2 Intermediate section, 3 Settling section, 4 Conical section;

[0017] 5 Microwave generator, 6 Ultrasonic generator, 7 Connecting elbow, 8 Lift pipe, 9 Primary hydrocyclone separator, 10 Secondary hydrocyclone separator, 11 Return pump, 12 Oil-containing reflux liquid, 13 Oil-containing reflux liquid in the lift pipe, 14 Oil-containing reflux liquid in the connecting elbow, 15 Oil-containing reflux liquid in the conical section, 16 Water-containing oil sludge feeding unit, 17 Rich oil storage tank, 18 Conditioning agent feeding port, 19 Screw feeder, 20 Feeding pipe, 21 Make-up water, 22 Water-solid mixture, 23 Rotary valve feeder DETAILED DESCRIPTION OF THE EMBODIMENTS

[0018] (Example 1) Demulsification of water-in-oil emulsion

[0019] See Figure 1, this system includes a water-containing oil sludge feeding unit 16, a three-stage demulsifier 1, a microwave generator 5, an ultrasonic generator 6, a connecting elbow 7, a riser 8, a primary hydrocyclone separator 9, a secondary hydrocyclone separator 10, a reflux pump 11, an oil-rich storage tank 17, a conditioning agent feeding port 18, a screw feeder 19, and a discharging pipe 20, which are connected in sequence. The system separates an oil-rich product and a water-solid mixture. The three-stage demulsifier 1 adopts a structure design with recycling of oil-containing reflux liquid, so that the oil-containing reflux liquid separated by the primary hydrocyclone separator 9 and the secondary hydrocyclone separator 10 is recycled to the three-stage demulsifier 1. The three-stage demulsifier 1 can be provided with a microwave generator 5 and an ultrasonic generator 6, so that the three-stage demulsifier 1 adopts a demulsification method combining recycling of oil-containing reflux liquid with microwave and ultrasonic.

[0020] The conditioning agent feeding system includes a conditioning agent feeding port 18, a screw feeder 19, and a discharging pipe 20. The three-stage demulsifier 1 includes an intermediate section 2, a settling section 3, and a conical section 4. The three-stage demulsifier 1 is connected to the conditioning agent feeding system through the discharging pipe 20. The conditioning agent feeding port 18 includes a rotary valve feeder 23 and a baffle below it. One, two, or more conditioning agents such as sulfuric acid, iron salts, aluminum salts, low-molecular anionic demulsifiers, low-molecular non-ionic surfactants, non-ionic high-molecular surfactants (such as higher alcohols, alkylphenols, alkylamines, phenolic resins), ultra-high molecular weight chemical demulsifiers, propylene oxide, butylene oxide, and tetrahydrofuran are fed into the three-stage demulsifier 1 through the discharging pipe. The material inside the discharging pipe 20 provides a material seal, and inert gas can be injected inside the screw feeder 19 to provide a gas seal. The settling section 3 of the three-stage demulsifier 1 is connected to the oil-rich storage tank 17 through a pipeline. The oil product inside the oil-rich storage tank 17 is discharged from the bottom, and the non-condensable gas is removed from its upper part. The water-containing oil sludge feeding unit 16 is connected to the bottom tangential position of the intermediate section 2 of the three-stage demulsifier 1 through a pipeline, and the makeup water 21 is connected to the bottom tangential position of the intermediate section 2 of the three-stage demulsifier 1 through a pipeline. The water-containing oil sludge and the makeup water 21 enter the intermediate section 2 in opposite tangential directions, forming a liquid-solid rotational flow, which greatly promotes the mixing of the conditioning agent and the water-containing oil sludge. The conical section 4 of the three-stage demulsifier 1 is connected to the riser 8 through a connecting elbow 7. The riser 8 is connected to the primary hydrocyclone separator 9 and the secondary hydrocyclone separator 10 through pipelines. The secondary hydrocyclone separator 10 is connected to the reflux pump 11 through a pipeline. The primary hydrocyclone separator 9 and the secondary hydrocyclone separator 10 are combined into a water-solid mixture through pipelines. After separation of water and solids, water and solid substances can be recycled respectively. The oil-containing reflux liquid coming out of the reflux pump 11 is divided into three paths, namely the riser oil-containing reflux liquid 13, the connecting elbow oil-containing reflux liquid 14, and the conical section oil-containing reflux liquid 15. The connecting elbow oil-containing reflux liquid 14 enters the connecting elbow 7 through a pipeline connection, the conical section oil-containing reflux liquid 15 enters the conical section 4 through a pipeline connection, and the riser oil-containing reflux liquid 13 enters the riser 8 through a pipeline connection.

[0021] The three-stage demulsifier 1 is divided into three stages. From bottom to top, the diameter of the reactor gradually increases, the diameter of the middle section remains unchanged, and the diameter of the settling section is the largest, which is conducive to slowing down the fluid velocity from bottom to top, thereby reducing the entrainment of water and solid substances into the oil-rich storage tank 17 and improving the separation efficiency of oil and water and oil and solid substances and the purity of the oil phase; a microwave generator 5 is arranged outside the middle section 2 of the three-stage demulsifier 1, and an ultrasonic generator 6 is arranged outside the settling section 3. The action of microwave and / or ultrasonic can promote the aggregation and growth of oil droplets and accelerate the oil-water separation, further improving the oil-water separation efficiency; when microwave irradiation is carried out, the magnetrons are arranged in pairs, and the three-stage demulsifier 1 needs to be configured with wave absorbent. When microwave heating is adopted, the main body shell of the middle section 2 is prepared from a ceramic weak wave absorbent material, which is convenient for the microwave to directly act on the liquid-solid mixture inside the three-stage demulsifier 1 rather than being absorbed by the main body shell material, and can effectively improve the energy utilization rate and system efficiency.

[0022] The conical section 4 of the three-stage demulsifier 1 is not provided with a gas distribution plate. The oil-containing return liquid 15 in the conical section enters the conical section 4 tangentially on the side surface of the conical section, forming a liquid-solid rotational flow, and the rotational direction is the same as the rotational direction of the water-containing oil sludge and the makeup water. The oil-containing return liquid 14 in the connecting elbow enters tangentially at the bottom of the connecting elbow 7, and the oil-containing return liquid 13 in the riser enters vertically upward at the bottom of the riser 8. A makeup water also injects vertically upward at the bottom of the riser 8, and together with the oil-containing return liquid, it provides power for the liquid-solid flow inside the riser.

[0023] The feeding pipe 20 enters at the top of the settling section 3 of the three-stage demulsifier 1. The end of the feeding pipe 20 is set as a straight pipe, and the opening of the straight pipe is vertically downward. The feeding pipe 20 extends deep into the bottom of the middle section 2 and the feeding pipe 20 is located at the radial middle position of the three-stage demulsifier 1. The bottom of the feeding pipe 20 is at the upper position in the vertical direction of the connecting pipe between the water-containing oil sludge feeding unit 16 and the middle section 2, and is also at the upper position in the vertical direction of the makeup water 21 at the inlet of the middle section 2. The liquid rotational flow of the middle section 2 and the conical section 4 forms a low-pressure area at the radial middle position of the middle section 2, which is convenient for the conditioning agent to enter the middle section 2 from the feeding pipe 20, promoting the liquid-solid mixing and oil-water stratification separation.

[0024] (Example 2) Demulsification of water-in-oil emulsion

[0025] See Figure 1 , the difference between this example and Example 1 is that: a microwave generator is arranged outside the middle section 2 of the three-stage demulsifier 1, and an ultrasonic generator may not be arranged outside the settling section 3 of the three-stage demulsifier 1. The main body shell of the middle section 2 is prepared from a weak wave absorbent material (such as quartz).

[0026] (Example 3) Demulsification of water-in-oil emulsion

[0027] See Figure 1 , the difference between this embodiment and Embodiment 1 is that: an ultrasonic generator is arranged outside the middle section 2 of the three-stage demulsifier 1, and a microwave generator 5 may not be arranged. The main body shell of the middle section 2 is made of a weakly microwave-absorbing material (such as quartz), and the rotary valve feeder 23 may also be a star feeder.

[0028] (Embodiment 4) Demulsification of water-in-oil emulsion

[0029] See Figure 1 , the difference between this embodiment and Embodiment 1 is that: an ultrasonic generator is arranged outside the middle section 2 of the three-stage demulsifier 1, and a microwave generator may also be arranged outside the sedimentation section 3 of the three-stage demulsifier 1.

[0030] (Embodiment 5) Demulsification of oil-in-water emulsion

[0031] See Figure 1 , the difference between this embodiment and Embodiment 1 is that: the conditioning agents used for the oil-in-water emulsion are electrolyte demulsifiers (such as hydrochloric acid, sodium chloride, magnesium chloride, calcium chloride, aluminum nitrate), low molecular weight alcohols, surfactants, polymers (such as cationic polymers, anionic polymers, non-ionic polymers).

[0032] The specific embodiments described above further elaborate on the purpose, technical solutions, and beneficial effects of the present invention. It should be understood that the above are only specific embodiments of the present invention and are not used to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims

1. A demulsification separation system for oil-water emulsion, characterized in that: The system includes a water-containing oil sludge feeding unit (16), a three-stage demulsifier (1), a microwave generator (5), an ultrasonic generator (6), a connecting elbow (7), a riser (8), a primary hydrocyclone separator (9), a secondary hydrocyclone separator (10), a reflux pump (11), a rich oil storage tank (17), a conditioning agent feeding port (18), a screw feeder (19) and a discharging pipe (20) connected in sequence. The system separates rich oil products and water-solid mixture (22); the three-stage demulsifier (1) adopts a structural design of recycling oil-containing reflux liquid, so that the oil-containing reflux liquid separated by the primary hydrocyclone separator (9) and the secondary hydrocyclone separator (10) is recycled to the three-stage demulsifier (1); the three-stage demulsifier (1) is provided with a microwave generator (5) and an ultrasonic generator (6), so that the three-stage demulsifier (1) adopts a demulsification method combining recycling of oil-containing reflux liquid and microwave and ultrasonic. The conditioning agent feeding system includes a conditioning agent feeding port (18), a screw feeder (19) and a discharging pipe (20). The three-stage demulsifier (1) includes an intermediate section (2), a settling section (3) and a conical section (4). The three-stage demulsifier (1) is connected to the conditioning agent feeding system through the discharging pipe (20). The settling section (3) of the three-stage demulsifier (1) is connected to the rich oil storage tank (17) through a pipeline. The water-containing oil sludge feeding unit (16) is connected to the tangential position at the bottom of the intermediate section (2) of the three-stage demulsifier (1) through a pipeline. Makeup water (21) is connected to the tangential position at the bottom of the intermediate section (2) of the three-stage demulsifier (1) through a pipeline. The conical section (4) of the three-stage demulsifier (1) is connected to the riser (8) through the connecting elbow (7). The riser (8), the primary hydrocyclone separator (9) and the secondary hydrocyclone separator (10) are connected in sequence through pipelines. The secondary hydrocyclone separator (10) is connected to the reflux pump (11) through a pipeline. The oil-containing reflux liquid (12) from the reflux pump (11) is divided into three paths, namely the riser oil-containing reflux liquid (13), the connecting elbow oil-containing reflux liquid (14) and the conical section oil-containing reflux liquid (15). The riser oil-containing reflux liquid (13) enters the riser (8) through a pipeline connection. The connecting elbow oil-containing reflux liquid (14) enters the connecting elbow (7) through a pipeline connection. The conical section oil-containing reflux liquid (15) enters the conical section (4) through a pipeline connection. The three-stage demulsifier (1) is divided into three sections. From bottom to top, the diameter of the reactor gradually increases, and the diameter of the intermediate section (2) remains unchanged. A microwave generator or an ultrasonic generator is arranged outside the intermediate section (2) of the three-stage demulsifier (1). An ultrasonic generator or a microwave generator is arranged outside the settling section (3). When microwave irradiation is carried out, the magnetrons are arranged in pairs, and an absorbent needs to be configured inside the three-stage demulsifier (1). When microwave heating is adopted, the main body shell of the intermediate section (2) is made of ceramic or quartz material.

2. The demulsification and separation system for an oil-water emulsion according to claim 1, characterized in that: The conical section (4) of the three-stage demulsifier (1) is not provided with a gas distribution plate. The oil-containing return liquid (15) in the conical section tangentially enters the conical section (4) from the side of the conical section (4), the oil-containing return liquid (14) in the connecting elbow tangentially enters at the bottom of the connecting elbow (7), and the oil-containing return liquid (13) in the riser vertically enters the riser (8) upward from the bottom of the riser (8).

3. The demulsification and separation system for an oil-water emulsion according to claim 1, characterized in that: The feed pipe (20) enters at the top of the settling section (3) of the three-stage demulsifier (1). The end of the feed pipe (20) is set as a straight pipe, and the opening of the straight pipe is vertically downward. The feed pipe (20) extends deep into the bottom of the middle section (2) and the feed pipe (20) is located at the radial middle position of the three-stage demulsifier (1). The bottom of the feed pipe (20) is at the upper position in the vertical direction of the connecting pipe between the water-containing oil sludge feeding unit (16) and the middle section (2), and is also at the upper position in the vertical direction at the inlet of the make-up water (21) to the middle section (2). The water-containing oil sludge feeding unit (16) is connected to the tangential position at the bottom of the middle section (2) through a pipeline, the make-up water (21) is connected to the three-stage demulsifier (1) through a pipeline at the tangential position at the bottom of the middle section (2), and the make-up water (21) is also connected to the riser (8) through a pipeline at the bottom of the riser (8).

4. The demulsification and separation system for an oil-water emulsion according to claim 1, characterized in that: The conditioning agent feeding port (18) includes a rotary valve feeder (23) or a star feeder and a baffle below it. The material inside the feed pipe (20) provides a material seal, and an inert gas is injected into the screw feeder (19) to provide a gas seal. The conditioning agent is a liquid or a solid at normal temperature.

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