Oily wastewater treatment methods

Abstract

The present invention belongs to the field of wastewater treatment technology, and in particular, is a method for treating oily wastewater, comprising the following steps: S1, using an oil separation and sedimentation device to perform static stratification on the wastewater, and then removing oil and precipitated matter; S2, using an oil-absorbing material to absorb the oil in the wastewater; S3, using a reverse osmosis filtration device to perform reverse osmosis filtration on the wastewater to obtain clean water and a concentrated liquid; S4, discharging or recycling the clean water, and again using the oil-absorbing material to absorb the oil in the concentrated liquid; S5, using a vacuum heating tank to crystallize the concentrated liquid, and passing the generated steam into an exhaust pipe, the inner wall of which is provided with an oil-absorbing material layer, which absorbs gaseous oil, and then the steam is emptied or cooled for recovery. The present invention uses reverse osmosis filtration to perform deep treatment on wastewater, which can remove most of the pollutants. The resulting clean water can be directly discharged or recycled, and the treatment effect is good.

Description

Technical Field

[0001] The invention belongs to the technical field of wastewater treatment, in particular to a method for treating oily wastewater. Background Art

[0002] Restaurant wastewater and some industrial wastewater contain large amounts of oil. This oil forms an oil film on the water surface, preventing oxygen from dissolving in the water, leading to hypoxia and making it difficult for aquatic organisms to survive. Furthermore, oily wastewater seeps into the soil, affecting soil permeability and water exchange. Therefore, oily wastewater must be treated before it can be discharged into natural water bodies.

[0003] Patent application number CN202310124635.1 discloses a system and method for the reuse of oily wastewater. The system utilizes a regulating tank for pretreatment, a separation tank to separate out most of the oil, which has a lower density than water, and an adsorption tank, adsorbent microorganisms, and oil-absorbing materials to absorb the oil from the water. A recovery tank recovers the oil-absorbing materials and adsorbent microorganisms, and a treatment tank for flocculation and sedimentation before discharge. Flocculation and sedimentation require a large amount of treatment agents, resulting in high costs and the introduction of new pollutants, which can affect treatment effectiveness. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a method for treating oily wastewater to improve the oil removal effect.

[0005] To solve the above problems, the technical solution adopted by the present invention is: a method for treating oily wastewater, comprising the following steps:

[0006] S1. Use oil separation and sedimentation equipment to statically stratify the wastewater, and then remove the oil on the wastewater surface and the sediment at the bottom of the wastewater;

[0007] S2. Use oil absorbing materials to absorb oil in wastewater;

[0008] S3, using reverse osmosis filtration equipment to perform reverse osmosis filtration on the wastewater to obtain clean water and concentrated liquid;

[0009] S4, draining or recycling the clean water, and using oil absorbing materials to absorb the oil in the concentrate again;

[0010] S5. A vacuum heating tank is used to crystallize the concentrated liquid. During the crystallization process, the generated steam is passed into an exhaust pipe. An oil-absorbing material layer is provided on the inner wall of the exhaust pipe. The oil-absorbing material layer is used to absorb gaseous oil, and then the steam is emptied or cooled for recovery.

[0011] Further, in step S1, the oil separation and sedimentation equipment includes an oil separation and sedimentation cylinder, which has an inner cavity with a circular cross-section, a vertical isolation cylinder is arranged in the center of the inner cavity, and a plurality of radially extending partitions are arranged between the isolation cylinder and the oil separation and sedimentation cylinder. The partitions divide the cavity between the isolation cylinder and the oil separation and sedimentation cylinder into a water inlet chamber, a plurality of stratified chambers and a drainage chamber arranged in sequence, and a water inlet connected to the water inlet chamber is provided on the side wall of the oil separation and sedimentation cylinder, and the water inlet chamber, the plurality of stratified chambers and the drainage chamber are connected in sequence through water holes arranged in the partition, and a drainage port connected to the drainage chamber is provided on the side wall of the oil separation and sedimentation cylinder; an oil drainage port connected to the water inlet chamber, the plurality of stratified chambers and the drainage chamber is provided on the top of the isolation cylinder, and an oil drainage mechanism is provided in the inner cavity of the isolation cylinder.

[0012] Furthermore, the oil discharge mechanism includes a support ring, the outer wall of the support ring is provided with a positioning boss, the inner wall of the isolation cylinder is provided with a vertically extending slide groove, the positioning boss is located in the slide groove and slides with the slide groove; a floating ring is fixedly provided on the upper surface of the support ring, and the density of the floating ring is less than the density of the oil; an oil collecting barrel is provided inside the support ring, the bottom wall of the oil collecting barrel is provided with multiple through holes, a flexible siphon tube is provided in the oil collecting barrel, and the siphon tube is connected to the oil collecting tank.

[0013] Furthermore, sewage pipes are provided at the bottoms of the water inlet chamber, the stratification chamber and the drainage chamber.

[0014] Furthermore, in step S2, the oil absorbing material is an oil absorbing ball that expands after absorbing oil, and a monitoring element is used to monitor the diameter of the oil absorbing ball. When the diameter of the oil absorbing ball reaches a set value, the oil absorbing ball is replaced.

[0015] Furthermore, the oil-absorbing balls are made of organic silicon polymer oil-absorbing materials.

[0016] Furthermore, after the oil-absorbing balls are fished out, de-oiling equipment is used to squeeze and de-oil the oil-absorbing balls, and then the oil-absorbing balls are used again.

[0017] Furthermore, step S2 is performed in an adsorption cylinder, wherein a wastewater inlet is provided at the bottom of the adsorption cylinder, a wastewater outlet is provided at the top, a detachable mesh cage is provided inside the adsorption cylinder, and a plurality of oil-absorbing balls are provided in the mesh cage;

[0018] The deoiling equipment includes an inclined deoiling cylinder, a plurality of oil drainage holes are provided on the side wall of the deoiling cylinder, and an oil collecting tank is provided under the deoiling cylinder; hard spheres with a particle size of 3 to 5 mm are provided in the deoiling cylinder, the deoiling cylinder is connected to a rotating drive mechanism for driving the deoiling cylinder to rotate, and extrusion blocks are provided inside the upper and lower ends of the deoiling cylinder, the extrusion blocks are in sliding cooperation with the deoiling cylinder, and the extrusion blocks are connected to the extrusion drive mechanism.

[0019] Furthermore, a jacket is provided on the outside of the upper end of the deoiling cylinder, the inner cavity of the deoiling cylinder is communicated with the inner cavity of the jacket, and a feed hopper is provided on the top of the jacket.

[0020] The beneficial effects of the present invention are: 1. The present invention uses reverse osmosis filtration to deeply treat wastewater, which can remove most of the pollutants. The obtained clean water can be directly discharged or recycled, and the treatment effect is good.

[0021] 2. The oil concentration in the concentrated liquid obtained by reverse osmosis filtration increases, so adsorption and oil removal are performed again.

[0022] 3. Salts in wastewater can be recovered by crystallizing the concentrated liquid. Residual oil will also evaporate in the vacuum heating tank, so an oil-absorbing material layer is set in the exhaust pipe to absorb the oil in the steam and prevent air pollution. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a schematic flow diagram of the present invention;

[0024] Figure 2 It is a schematic diagram of the front and cross-section of the oil separation and sedimentation equipment of the present invention;

[0025] Figure 3 yes Figure 2 Middle AA cross-sectional view;

[0026] Figure 4 It is a schematic diagram of the adsorption cylinder;

[0027] Figure 5 It is a schematic diagram of the deoiling equipment;

[0028] Figure 6 It is a schematic diagram of the exhaust pipe;

[0029] Figure numerals: 1—exhaust pipe; 2—oil-absorbing material layer; 3—oil-separating sedimentation cylinder; 4—isolating cylinder; 5—partition; 6—water inlet chamber; 7—stratification chamber; 8—drainage chamber; 9—water inlet; 10—water hole; 11—drainage outlet; 12—oil discharge outlet; 13—support ring; 14—positioning boss; 15—floating ring; 16—oil collecting barrel; 17—siphon; 18—oil collecting pool; 19—drain pipe; 200—adsorption cylinder; 201—wastewater inlet; 202—wastewater outlet; 203—net cage; 206—deoiling cylinder; 207—oil collecting trough; 208—rotation drive mechanism; 209—extrusion block; 210—extrusion drive mechanism; 211—jacket; 212—feed hopper. DETAILED DESCRIPTION

[0030] The present invention will be further described below with reference to the accompanying drawings and examples.

[0031] The oily wastewater treatment method of the present invention is as follows: Figure 1 As shown, the following steps are included:

[0032] S1. Use oil separation and sedimentation equipment to statically stratify the wastewater, and then remove the oil on the wastewater surface and the sediment at the bottom of the wastewater.

[0033] Wastewater often contains solid impurities. By allowing the wastewater to stand for stratification, the less dense oil in the water rises to the surface, while the solid impurities settle to the bottom, effectively separating the solids, water, and oil. The oil on the wastewater surface can be recycled. After standing for stratification, the majority of the oil in the wastewater can be removed.

[0034] S2. Use oil absorbing materials to absorb the oil in the wastewater.

[0035] After standing and stratification, a small amount of oil remains in the wastewater, so oil-absorbing materials are used to absorb the oil in the wastewater to achieve further oil removal from the wastewater.

[0036] S3. Use reverse osmosis filtration equipment to perform reverse osmosis filtration on the wastewater to obtain clean water and concentrated liquid.

[0037] After stratification and adsorption degreasing, most of the solid particles and oil in the wastewater are removed, and the concentration of pollutants in the water is reduced. However, a small amount of oil and other pollutants may still remain. For example, restaurant wastewater contains not only a large amount of oil, but also organic matter, salts and other pollutants. To fully remove these pollutants, the present invention uses reverse osmosis filtration to deeply treat the wastewater. Reverse osmosis filtration can remove various types of pollutants such as organic matter, salts, and bacteria, with good treatment effects, resulting in clean water and concentrated liquid.

[0038] S4. Discharge or recycle the clean water, and use oil-absorbing materials to absorb the oil in the concentrate again.

[0039] The clean water obtained by reverse osmosis filtration meets the standards for direct discharge and can be discharged directly or recycled for reuse. However, the oil concentration in the concentrate increases, so oil absorption materials are used to absorb the oil again to further remove the oil from the concentrate.

[0040] S5. The concentrated liquid is crystallized using a vacuum heating tank. During the crystallization process, the generated steam is passed into the exhaust pipe 1. The inner wall of the exhaust pipe 1 is provided with an oil-absorbing material layer 2. The oil-absorbing material layer 2 absorbs the gaseous oil, and then the steam is emptied or cooled for recovery.

[0041] After degreasing, the concentrated wastewater contains components such as oil salts, organic matter, and a small amount of residual oil. Therefore, it is passed through a vacuum heating tank for crystallization. The resulting steam is primarily water vapor, along with some low-boiling-point oil. This steam is then passed through an exhaust pipe 1, where an oil-absorbing material layer 2 absorbs the oil from the steam, preventing it from being released into the air and causing air pollution. The oil-absorbing material layer 2 can be made of existing oil-absorbing, non-water-absorbing materials, such as graphene oil-absorbing sponge or carbon sponge. Some of the oil remains in liquid form and mixes with the solid crystals. After filtration, the resulting crystals and oil are recovered, each of which can be recycled.

[0042] In step S1, the oil separation and sedimentation equipment is as follows Figure 2 and Figure 3 As shown, it includes an oil-separating sedimentation cylinder 3, which is a cylinder. The oil-separating sedimentation cylinder 3 has an inner cavity with a circular cross-section, and a vertical isolation cylinder 4 is arranged in the center of the inner cavity. The isolation cylinder 4 can also be a cylinder. A plurality of radially extending partitions 5 are arranged between the isolation cylinder 4 and the oil-separating sedimentation cylinder 3. The partition 5 divides the cavity between the isolation cylinder 4 and the oil-separating sedimentation cylinder 3 into a water inlet chamber 6, a plurality of stratified chambers 7 and a drainage chamber 8 arranged in sequence. The side wall of the oil-separating sedimentation cylinder 3 is provided with a water inlet 9 connected to the water inlet chamber 6. The water inlet chamber 6, the plurality of stratified chambers 7 and the drainage chamber 8 are connected in sequence through a water hole 10 arranged on the partition 5. The side wall of the oil-separating sedimentation cylinder 3 is provided with a drainage port 11 connected to the drainage chamber 8; the top of the isolation cylinder 4 is provided with an oil drainage port 12 connected to the water inlet chamber 6, the plurality of stratified chambers 7 and the drainage chamber 8, and an oil drainage mechanism is provided in the inner cavity of the isolation cylinder 4.

[0043] The oily wastewater enters the water inlet chamber 6 through the water inlet 9. The water inlet 9 can be set at the bottom of the water inlet chamber 6. The oil in the water gradually floats to the water surface, the solid lower layer goes to the water bottom, and the water is in the middle. Then the water in the water inlet chamber 6 enters the stratification chamber 7 through the water hole 10. After multiple stratifications, the wastewater enters the drainage chamber 8 and is then discharged from the drain port 11. The drain port 11 can be set in the middle of the drainage chamber 8. The solids, water and oil are stratified in the water inlet chamber 6, the stratification chamber 7 and the drainage chamber 8. The oil on the water surface of the water inlet chamber 6, the stratification chamber 7 and the drainage chamber 8 enters the inner cavity of the isolation cylinder 4 through the oil drain port 12, and is then discharged by the oil discharge mechanism to achieve oil separation and recovery. In order to extend the flow distance of water in the oil separation sedimentation cylinder 3 and increase the residence time, vertical baffles can be set in the water inlet chamber 6 and the stratification chamber 7 to form a curved water flow path.

[0044] During the stratification process, water is in the middle, oil is at the surface, and solid impurities are at the bottom. Therefore, water passage 10 is positioned in the middle of baffle 5. As wastewater sequentially enters each stratification chamber 7 and drainage chamber 8, the oil content in the wastewater gradually decreases. This multiple stratification process improves oil removal efficiency. The height of oil drain port 12 is slightly higher than the interface between the wastewater and oil layers, ensuring that oil can enter isolation tube 4 while preventing water from entering.

[0045] In the present invention, the oil discharge mechanism includes a support ring 13, the outer wall of which is provided with a positioning boss 14. The support ring 13 and the positioning boss 14 are made of a material with a low density, such as plastic, and can be integrally formed. The inner wall of the isolation cylinder 4 is provided with a vertically extending slide groove, and the positioning boss 14 is located in the slide groove and slides with the slide groove. A floating ring 15 is fixedly provided on the upper surface of the support ring 13. The density of the floating ring 15 is less than that of the oil, and specifically, an airbag can be used. An oil collecting barrel 16 is provided inside the support ring 13. The oil collecting barrel 16 can be made of plastic. The bottom wall of the oil collecting barrel 16 is provided with multiple through holes. A flexible siphon tube 17 is provided inside the oil collecting barrel 16. The end of the siphon tube 17 is fixed inside the oil collecting barrel 16, and the siphon tube 17 is connected to the oil collecting tank 18. Under the action of the floating ring 15, the support ring 13, the positioning boss 14 and the like can float on the liquid surface as a whole, and automatically move up and down as the height of the liquid level changes, ensuring that the bottom wall of the oil collecting barrel 16 is always immersed in the oil, thereby ensuring that the end of the siphon tube 17 is always located in the oil, so that the oil can be discharged stably. Under the action of the siphon, the oil can flow along the siphon tube 17 to the siphon tube 17 for recovery. The oil discharge mechanism of the present invention does not use power equipment such as oil pumps and has no energy consumption. In addition, a small amount of water will also enter the oil collecting barrel 16 and settle to the bottom of the oil collecting barrel 16. Controlling the liquid level in the oil collecting pool 18 to always be higher than the oil-water interface height in the oil collecting barrel 16 can avoid transporting water from the bottom of the oil collecting barrel 16 to the oil collecting pool 18.

[0046] In order to facilitate the removal of solid sediment at the bottom of the water inlet chamber 6, the stratification chamber 7 and the drainage chamber 8, a sewage pipe 19 is provided at the bottom of the water inlet chamber 6, the stratification chamber 7 and the drainage chamber 8. A sewage valve or sewage pump can be provided on the sewage pipe 19. The sewage valve or sewage pump is opened at regular intervals to discharge the solid sediment.

[0047] In step S2, the oil-absorbing material can be any of a variety of existing oil-absorbing, non-water-absorbing materials. While conventional oil-absorbing materials offer good oil absorption, they have a limited oil absorption capacity. When the oil absorption capacity approaches saturation, the material must be replaced with a new one. However, existing oil-absorbing materials are difficult to accurately determine their oil absorption capacity and schedule, requiring only periodic replacement. This can easily lead to some parts of the material becoming saturated while others remain unsaturated. To address this issue and facilitate replacement of the oil-absorbing material, the present invention utilizes an oil-absorbing ball that expands after absorbing oil. The ball is replaced when its diameter reaches a set value.

[0048] During use, multiple oil-absorbing balls are put into wastewater. The oil-absorbing balls gradually absorb oil and expand, causing their diameter to gradually increase. After the amount of oil absorbed by the oil-absorbing balls reaches a set value, the diameter of the oil-absorbing balls also increases to the set value. Therefore, it is possible to determine whether the oil absorption has reached or is close to saturation by monitoring the diameter of the oil-absorbing balls. The diameter of the oil-absorbing balls before absorbing oil is about 10 mm, and the diameter of the oil-absorbing balls after absorbing oil reaches or is close to saturation can be obtained through an oil absorption test. The present invention can intuitively and accurately determine whether the oil absorption has reached saturation through the diameter of the oil-absorbing balls, thereby replacing the oil-absorbing balls in a timely manner to ensure the utilization effect of the oil-absorbing balls. The diameter of the oil-absorbing balls can be monitored by manual observation, or by using a monitoring element, such as a camera element.

[0049] In a preferred embodiment, the oil-absorbing balls are made of organosilicon polymer oil-absorbing material. These materials have excellent oil absorption properties, capable of absorbing 6 to 14 times their own weight in oil. They require no frequent replacement and expand after absorbing oil, making it easier to visually assess the amount of oil absorbed. Furthermore, after absorbing oil, organosilicon polymer oil-absorbing materials can be squeezed out to remove the absorbed oil, allowing for recycling. Therefore, in step S2, when replacing the oil-absorbing balls, they are removed and then squeezed out using de-oiling equipment before being reused.

[0050] Step S2 is performed in the adsorption cylinder 200, as shown in FIG. Figure 4 As shown, the adsorption cylinder 200 is provided with a wastewater inlet 201 at the bottom and a wastewater outlet 202 at the top. A removable mesh cage 203 is located inside the adsorption cylinder 200, which contains multiple oil-absorbing balls. Because the density of organic silicone polymer oil-absorbing materials is generally lower than that of water, the oil-absorbing balls will float on the water surface. Therefore, the oil-absorbing balls are placed in the mesh cage 203, which is then placed inside the adsorption cylinder 200, so that the entire mesh cage 203 is submerged in water, ensuring sufficient contact between the wastewater and the oil-absorbing balls. When the oil-absorbing balls need to be replaced, the entire mesh cage 203 is removed and a new mesh cage 203, containing several new oil-absorbing balls, is placed inside the adsorption cylinder 200.

[0051] The oil-absorbing balls can be squeezed by a common squeezing method to squeeze out the oil in the oil-absorbing balls. Since the diameter of the expanded oil-absorbing balls is large and there is a gap between the oil-absorbing balls, it is difficult to squeeze the entire surface of the oil-absorbing balls evenly when squeezing the oil-absorbing balls, resulting in insufficient deoiling. The deoiling equipment of the present invention is as follows Figure 5 As shown, the deoiling drum 206 includes an inclined deoiling drum 206 with multiple oil drainage holes on its sidewall. Deoiling drum 206 can be made of stainless steel and is provided with multiple small oil drainage holes. An oil collecting trough 207 is located below deoiling drum 206 to collect the removed oil. Hard spheres with a diameter of 3 to 5 mm are placed inside deoiling drum 206. These hard spheres can be metal or high-strength plastic. The de-oiling cylinder 206 is connected to a rotating drive mechanism 208 for driving the de-oiling cylinder 206 to rotate. The rotating drive mechanism 208 can adopt a reduction motor. Extrusion blocks 209 are provided inside the upper and lower ends of the de-oiling cylinder 206. The extrusion blocks 209 slide with the de-oiling cylinder 206, and the extrusion blocks 209 are connected to an extrusion drive mechanism 210. The extrusion drive mechanism 210 can drive the extrusion block 209 to move in a straight line, so that the extrusion block 209 can enter and exit the de-oiling cylinder 206 and can squeeze the oil-absorbing ball. The extrusion drive mechanism 210 can specifically adopt equipment such as a cylinder and a hydraulic cylinder. During deoiling, the oil-absorbing balls in the net cage 203 are poured into the deoiling cylinder 206. Simultaneously, an appropriate amount of hard spheres are added to the cylinder 206. The rotary drive mechanism 208 then rotates the cylinder 206 for a period of time to evenly mix the hard spheres and the oil-absorbing balls. Finally, the extrusion drive mechanism 210 moves the extrusion block 209, which squeezes the oil-absorbing balls. The squeezed oil falls through the drain hole into the oil sump 207. Because the hard spheres are mixed with the oil-absorbing balls, they fill the gaps between them. During extrusion, the hard spheres come into contact with the balls, generating a squeezing force. This increases the area of ​​the balls squeezed, ensuring a more balanced squeezing force across all parts of the balls, thus improving the deoiling effect. After deoiling, the extrusion drive mechanism 210 drives the extrusion block 209 to the end of the deoiling cylinder 206. The rotation drive mechanism 208 then rotates the deoiling cylinder 206 again, causing the squeezed oil-absorbing balls to disperse. The extrusion drive mechanism 210 then drives the extrusion block 209 at the lower end of the deoiling cylinder 206 to separate from the deoiling cylinder 206. The lower end of the deoiling cylinder 206 opens, and the oil-absorbing balls and hard spheres can be discharged from the deoiling cylinder 206. The diameter of the oil-absorbing balls is larger than that of the hard spheres. The oil-absorbing balls and hard spheres are separated by screening, and both the oil-absorbing balls and hard spheres can be reused.

[0052] In order to facilitate the loading of oil-absorbing balls and hard spheres into the deoiling cylinder 206 , a jacket 211 is provided on the outer upper end of the deoiling cylinder 206 . The inner cavity of the deoiling cylinder 206 is connected to the inner cavity of the jacket 211 , and a feed hopper 212 is provided on the top of the jacket 211 .

[0053] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A method for treating oily wastewater, characterized in that: The following steps are involved: S1. Use oil separation and sedimentation equipment to statically stratify the wastewater, and then remove the oil on the wastewater surface and the sediment at the bottom of the wastewater; S2. Use oil absorbing materials to absorb oil in wastewater; The oil absorbing material is an oil absorbing ball that expands after absorbing oil. When the diameter of the oil absorbing ball reaches the set value, the oil absorbing ball should be replaced; The oil absorbing ball is an organic silicon polymer oil absorbing material; After the oil-absorbing balls are fished out, they are squeezed and de-oiled using de-oiling equipment, and then reused. This step is carried out in an adsorption cylinder (200). The bottom of the adsorption cylinder (200) is provided with a wastewater inlet (201), the top is provided with a wastewater outlet (202), and a detachable net box (203) is provided inside the adsorption cylinder (200). A plurality of oil-absorbing balls are provided in the net box (203); The deoiling device comprises an inclined deoiling cylinder (206), a side wall of the deoiling cylinder (206) is provided with a plurality of oil drain holes, and an oil collecting tank (207) is provided below the deoiling cylinder (206); hard spheres with a particle size of 3 to 5 mm are provided in the deoiling cylinder (206), the deoiling cylinder (206) is connected to a rotation drive mechanism (208) for driving the deoiling cylinder (206) to rotate, and an extrusion block (209) is provided inside the upper end and the lower end of the deoiling cylinder (206), the extrusion block (209) is in sliding cooperation with the deoiling cylinder (206), and the extrusion block (209) is connected to an extrusion drive mechanism (210); S3, using reverse osmosis filtration equipment to perform reverse osmosis filtration on the wastewater to obtain clean water and concentrated liquid; S4, draining or recycling the clean water, and using oil absorbing materials to absorb the oil in the concentrate again; S5. A vacuum heating tank is used to crystallize the concentrated liquid. During the crystallization process, the generated steam is passed into an exhaust pipe (1). An oil-absorbing material layer (2) is provided on the inner wall of the exhaust pipe (1). The oil-absorbing material layer (2) absorbs gaseous oil, and then the steam is emptied or cooled for recovery.

2. The method for treating oily wastewater according to claim 1, wherein: In step S1, the oil separation and sedimentation equipment includes an oil separation and sedimentation cylinder (3), the oil separation and sedimentation cylinder (3) has an inner cavity with a circular cross section, a vertical isolation cylinder (4) is provided at the center of the inner cavity, a plurality of radially extending partitions (5) are provided between the isolation cylinder (4) and the oil separation and sedimentation cylinder (3), the partitions (5) divide the cavity between the isolation cylinder (4) and the oil separation and sedimentation cylinder (3) into a water inlet cavity (6), a plurality of layered cavities (7) and a drainage cavity (8) which are arranged in sequence, and the oil separation and sedimentation cylinder (3) is provided with a plurality of radially extending partitions (5). ) is provided with a water inlet (9) communicating with the water inlet chamber (6), the water inlet chamber (6), the plurality of stratified chambers (7) and the drainage chamber (8) are connected in sequence through a water hole (10) provided on the partition (5), and the side wall of the oil separation sedimentation cylinder (3) is provided with a drainage port (11) communicating with the drainage chamber (8); the top of the isolation cylinder (4) is provided with an oil drainage port (12) communicating with the water inlet chamber (6), the plurality of stratified chambers (7) and the drainage chamber (8), and an oil drainage mechanism is provided in the inner cavity of the isolation cylinder (4).

3. The method for treating oily wastewater according to claim 2, wherein: The oil discharge mechanism comprises a support ring (13), the outer wall of the support ring (13) is provided with a positioning boss (14), the inner wall of the isolation cylinder (4) is provided with a vertically extending slide groove, the positioning boss (14) is located in the slide groove and slides with the slide groove; a floating ring (15) is fixedly provided on the upper surface of the support ring (13), and the density of the floating ring (15) is less than the density of oil; an oil collecting barrel (16) is provided inside the support ring (13), the bottom wall of the oil collecting barrel (16) is provided with a plurality of through holes, a flexible siphon tube (17) is provided in the oil collecting barrel (16), and the siphon tube (17) is connected to an oil collecting pool (18).

4. The method for treating oily wastewater according to claim 2, wherein: A sewage pipe (19) is provided at the bottom of the water inlet chamber (6), the stratification chamber (7) and the drainage chamber (8).

5. The method for treating oily wastewater according to claim 1, wherein: A jacket (211) is provided on the outside of the upper end of the deoiling cylinder (206), the inner cavity of the deoiling cylinder (206) is communicated with the inner cavity of the jacket (211), and a feed hopper (212) is provided on the top of the jacket (211).

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