An oil-water deep separation device and process for petrochemical oil refining

Abstract

The present invention relates to the technical field of dissolved gas tanks, and discloses an oil-water deep separation device and process for petrochemical oil refining, wherein the oil-water deep separation device for petrochemical oil refining comprises a tank body, and also comprises a dissolved gas cavity formed between a partition and the bottom of the tank body, a dissolved gas pipe connected to the dissolved gas cavity is arranged on the tank body, and a plurality of nested annular low plates and annular high plates are arranged above the partition, the annular low plates and the annular high plates are arranged at intervals, the innermost of the plurality of nested annular low plates and annular high plates is the annular low plate, and the highest end of the annular low plate is lower than the highest end of the annular high plate. The oil-water deep separation device for petrochemical oil refining allows the liquid to be treated to circulate up and down between the plurality of annular low plates and annular high plates, thereby increasing the adhesion time of oil droplets and impurity floccules with microbubbles, and each time the liquid to be treated circulates up and down, the skimming port skims off floating oil and impurities, and after multi-stage impurity skimming, the contaminant content of the liquid to be treated will be greatly reduced.

Description

Technical Field

[0001] The invention relates to the technical field of air flotation tanks, and in particular to an oil-water deep separation device and process for petrochemical oil refining. Background Art

[0002] The flotation tank is a device used in water treatment processes and is widely used in industrial water treatment, municipal sewage treatment, oil-water separation and other fields. Its main function is to introduce tiny bubbles so that solid particles, grease and other impurities suspended in the water adhere to the bubbles, forming scum and rising to the water surface for subsequent removal. The working principle of the flotation tank usually includes the following steps: dissolving air into water through the dissolved air system to form dissolved air water, and releasing the dissolved air water into the treated water. Due to the sudden decrease in pressure, the dissolved air is released to form a large number of tiny bubbles, and suspended particles, grease and other impurities in the water adhere to the bubbles. The impurities attached to the bubbles float to the liquid surface to form scum, which is then removed by scraping equipment. This treatment method is highly efficient and suitable for treating wastewater containing floatable impurities.

[0003] The patent with the patent publication number CN107324432A discloses a dissolved air flotation tank, which includes a tank body, an upper head, a lower head, a filler mounting frame, and a conical cylinder. The filler mounting frame is provided with agglomeration fillers and a conical cylinder. The lower side of the conical cylinder is provided with a sewage pipe, the upper side of the conical cylinder is provided with an outer cylinder, the outer cylinder is provided with an inner cylinder, a swirl water inlet pipe is tangentially welded on the side wall of the inner cylinder, an insertion pipe is inserted in the swirl water inlet pipe, and the insertion pipe is connected to a static mixer and a water inlet; the tank body is provided with a scum discharge port on the upper head, and the tank body is provided with a sewage pipe on the lower head; a closed clean water zone is formed between the conical cylinder and the lower head, and a plurality of water distribution square pipes connecting the tank body and the clean water zone are evenly arranged on the lower surface of the conical cylinder; the clean water zone is provided with a water outlet on the side wall of the tank body.

[0004] From the above existing technologies, we can see that the traditional treatment method of wastewater produced by oil refineries is basically based on the Archimedean buoyancy principle of gravity sedimentation, so the separation efficiency is very low for low-concentration two-phase mixed liquids containing only a few hundred ppm of oil. However, the centrifugal separation based on cyclone technology can reach hundreds or even thousands of times the acceleration of gravity, so the separation efficiency will be significantly improved. At the same time, this technology has played a good role in the separation of oil, gas and water in the joint treatment station of the oil production plant and the separation of oil, gas and water in the offshore oil production platform. After the technology is properly improved, it should be able to play a good role in the pretreatment of wastewater produced by the refinery. Dissolved air flotation technology has been successfully applied in the pretreatment of wastewater produced by refineries. However, the traditional dissolved air flotation technology used by refineries is to first pressurize and gasify the wastewater, and then reduce the pressure to precipitate microbubbles to achieve the flotation effect. However, this technology is also strict in controlling the amount of water and gas in the dissolved air water, and the pressure difference between the dissolved air pump and the flotation tank. Therefore, when used on industrial sites, it is difficult to debug. This technical solution generates a circulating flow in the flotation tank, prolongs the migration path and time of oil droplets and impurity flocs in the flotation tank, and increases the probability of oil droplets and impurity flocs adhering to microbubbles. The separation efficiency will be higher, the effect will be better, and the difficulty of operation and debugging can be reduced. Summary of the invention

[0005] In view of the above problems in the prior art, an oil-water deep separation device and method for petrochemical refining are proposed.

[0006] One aspect of the present application provides an oil-water deep separation device for petrochemical refining, the purpose of which is to: generate a circulating flow in the flotation tank, extend the migration path and time of oil droplets and impurity flocs in the flotation tank, increase the probability of oil droplets and impurity flocs adhering to microbubbles, and improve the separation efficiency.

[0007] The technical solution of the present invention is: an oil-water depth separation device for petrochemical oil refining, comprising a tank body, and also comprising a baffle plate arranged at the lower part of the tank body, a dissolved gas cavity is formed between the baffle plate and the bottom of the tank body, a dissolved gas pipe connected to the dissolved gas cavity is arranged on the tank body, a plurality of nested annular low plates and annular high plates are arranged above the baffle plate, the annular low plates and the annular high plates are arranged at intervals, the innermost side of the plurality of nested annular low plates and annular high plates is the annular low plate, the highest end of the annular low plate is lower than the highest end of the annular high plate, a sewage outlet is arranged above the side wall of the tank body, a water outlet is arranged below the side wall of the tank body, a water inlet is arranged at the bottom of the tank body, and the height of the sewage outlet does not exceed the height of the annular high plate The highest point of the annular low plate is arranged above the partition, the water inlet pipe passes through the dissolved air cavity and is connected with the inner side of the innermost annular low plate, a plurality of connecting ports are arranged at the bottom end of the annular high plate, a U-shaped sewage skimming pipe is arranged at the sewage outlet, the sewage skimming pipe extends from the sewage outlet and fits to the innermost annular low plate, a plurality of groups of sewage skimming ports are arranged on the sewage skimming pipe, the plurality of groups of sewage skimming ports are distributed in the compartment between the outer side of the annular low plate and the annular high plate, a plurality of dissolved air release holes are arranged on the partition, the liquid to be treated enters the inner side of the annular low plate through the water inlet pipe, overflows into the inner side of the adjacent annular high plate from the highest point of the annular low plate, and then enters the inner side of the next adjacent annular low plate through the connecting port, circulates in sequence and finally flows out from the water outlet.

[0008] By adopting the above scheme, the liquid to be treated circulates up and down between multiple annular low plates and annular high plates, increasing the adhesion time of oil droplets, impurity flocs and microbubbles. Each time the liquid to be treated circulates up and down, the skimming port skims off floating oil and impurities. After multi-stage impurity skimming, the pollution content of the liquid to be treated will be greatly reduced.

[0009] Furthermore, the top ends of several of the annular low plates are each provided with an annular inclined weir inclined inwardly, and the heights of the several annular inclined weirs decrease sequentially from the inside to the outside.

[0010] By adopting the above scheme, an annular inclined weir is set, so that when the liquid to be treated flows out from the upper end of the annular low plate, the flow rate of the liquid to be treated in the compartment is increased, which promotes pollutants such as hydrocarbons lighter than water to rise to the surface of the compartment, while cleaner and therefore heavier water is pushed toward the bottom of the tank body.

[0011] Furthermore, the heights of the plurality of sewage skimming ports decrease sequentially from the inside to the outside, and the sewage skimming ports in the same compartment have the same height.

[0012] By adopting the above scheme, by setting successively lowered sewage removal ports, multi-stage impurity removal can be achieved, and the amount of pollution in the liquid to be treated will be greatly reduced.

[0013] Furthermore, the bottom edge of the dirt-skimming port is configured to be wavy.

[0014] According to the above solution, the bottom edge of the skimming port is arranged to be wavy in shape, so as to facilitate the entry of unwanted impurities into the skimming pipe.

[0015] Furthermore, a plurality of balancing holes are vertically arranged on the annular high plate and the annular low plate, and the positions of the balancing holes on adjacent annular high plates and annular low plates are offset.

[0016] By adopting the above scheme, by setting a balancing hole, the liquid levels in these adjacent compartments can be balanced, avoiding short-circuiting of liquid in adjacent compartments without significantly reducing the pollutant content; avoiding short-circuiting of liquid through the tank increases the residence time in the tank, so that more pollutants can be skimmed off the top of the liquid in each compartment.

[0017] Furthermore, the water inlet pipe extends to above the partition, the water inlet pipe is covered with a cover plate, the part of the water inlet pipe above the partition is provided with water inlet holes, and the dissolved gas release holes are distributed in an annular manner on the partition below the cover plate.

[0018] By adopting the above scheme, the liquid to be treated fully merges with the microbubbles released from the dissolved gas release holes when passing through the slit formed by the cover plate. The arrangement of introducing bubbles or microbubbles in a narrow area increases the possibility of contact or adhesion with pollutants in the fluid.

[0019] Furthermore, a plant-shaped block is arranged between the outer side of the annular low plate and the inner side of the annular high plate, and the dissolved gas release holes are distributed in an annular manner on the partition plate below the plant-shaped block.

[0020] By adopting the above scheme, the liquid to be treated fully merges with the microbubbles released from the dissolved gas release holes when passing through the slits formed by the factory-shaped blocks. The arrangement of introducing bubbles or microbubbles in a narrow area increases the possibility of contact or adhesion with pollutants in the fluid.

[0021] Furthermore, the height of the plant-shaped block at the outermost side is higher than the sewage outlet.

[0022] By adopting the above scheme, the liquid to be treated flows out after passing through the slit formed by the factory-shaped block, and the arrangement of introducing bubbles or microbubbles in the narrow area increases the possibility of contact or adhesion with pollutants in the fluid.

[0023] Another aspect of the present invention provides a deep oil-water separation process for petrochemical oil refining, which uses a flotation system composed of a deep oil-water separation device for petrochemical oil refining, comprising the following steps:

[0024] Step 1: Pre-treat the oil-water mixture by coarse filtration or sedimentation to remove larger suspended particles and impurities;

[0025] Step 2: Add appropriate amount of chemical agents, such as flocculants and demulsifiers, to the pretreated mixed liquor to promote the aggregation of oil droplets to form larger flocs, which is a key step to prepare for subsequent separation;

[0026] Step 3: Use high-speed cyclone technology of a cylindrical cyclone tube to evenly stir and mix the mixed liquid with the added reagent. This process promotes further aggregation of oil droplets and preliminarily separates a portion of oil and water;

[0027] Step 4: Use an air dissolving pump to dissolve air in the treated water to form high-concentration air-dissolved water, ready for use in the tank;

[0028] Step 5: Introduce dissolved gas water into the tank, quickly reduce the pressure to release dissolved gas, and generate a large number of tiny bubbles. The microbubbles combine with oil droplets and impurity flocs in the water, adhere to each other under the action of surface tension, and form flocs with greater buoyancy;

[0029] Step 6: Set up a circulating flow in the tank to extend the contact time and path of oil droplets and impurity flocs with microbubbles by increasing the rotational motion of the liquid;

[0030] Step 7: Oil droplets and adherent floccules quickly float to the water surface under the action of Archimedean buoyancy, thus being separated from the clean water, and the oil layer and floccules floating on the surface are removed through the skimmer pipe;

[0031] Step 8: The clean water after deep treatment is discharged from the bottom of the tank and sent to the next process stage or reused after quality inspection.

[0032] By adopting the above scheme and through these steps, the oil and impurities in the oil-water mixture are effectively separated, which can meet the needs of efficient treatment of wastewater in the petrochemical refining process.

[0033] Beneficial effects of the present invention:

[0034] 1. The liquid to be treated circulates up and down between multiple annular low plates and annular high plates to increase the adhesion time of oil droplets, impurity flocs and microbubbles. Every time the liquid to be treated circulates up and down, the skimming port skims off floating oil and impurities. After multi-stage impurity skimming, the pollution content of the liquid to be treated will be greatly reduced.

[0035] 2. By setting the balance holes, the liquid levels in these adjacent compartments can be equalized, avoiding the short circuit of the liquid in the adjacent compartments without significantly reducing the pollutant content; avoiding the short circuit of the liquid through the tank increases the residence time in the tank, so that more pollutants are skimmed from the top of the liquid in each compartment.

[0036] 3. When the treated liquid passes through the slit formed by the cover plate and the factory-shaped block, it fully merges with the microbubbles released from the dissolved gas release holes. The setting of introducing bubbles or microbubbles in a narrow area increases the possibility of contact or adhesion with pollutants in the fluid. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 It is a stereoscopic diagram of the oil-water deep separation device used in petrochemical oil refining of the present invention;

[0038] Figure 2 It is a top view of the oil-water deep separation device used in petrochemical oil refining of the present invention;

[0039] Figure 3 For the present invention Figure 2 Sectional view at AA;

[0040] Figure 4 This is a diagram showing the internal structure of a tank in an oil-water deep separation device used in petrochemical oil refining according to the present invention;

[0041] Figure 5 For the present invention Figure 4 Exploded diagram of

[0042] Figure 6 It is a half-section stereoscopic view of the oil-water deep separation device used in petrochemical oil refining of the present invention;

[0043] Figure 7 This is a flow path diagram of the liquid to be treated in the oil-water deep separation device used in petrochemical oil refining of the present invention;

[0044] Figure 8 The present invention is a flotation system diagram for the oil-water deep separation process used in petrochemical oil refining.

[0045] In the figure:

[0046] 1. Tank body; 2. Partition; 3. Dissolved gas cavity; 4. Dissolved gas pipe; 5. Annular low plate; 6. Annular high plate; 7. Sewage outlet; 8. Water outlet; 9. Water inlet pipe; 10. Connecting port; 11. Sewage skimming pipe; 12. Sewage skimming port; 13. Dissolved gas release hole; 14. Annular inclined weir; 15. Balance hole; 16. Cover plate; 17. Water inlet hole; 18. Factory block. DETAILED DESCRIPTION

[0047] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the accompanying drawings.

[0048] Example 1, reference Figure 1-7, which is the first embodiment of the present invention, provides an oil-water depth separation device for petrochemical refining, including a tank body 1, and also including a partition 2 arranged at the lower part of the tank body 1, a dissolved gas cavity 3 is formed between the partition 2 and the bottom of the tank body 1, and a dissolved gas pipe 4 connected to the dissolved gas cavity 3 is arranged on the tank body 1, and a plurality of nested annular low plates 5 and annular high plates 6 are arranged above the partition 2, and the annular low plates 5 and the annular high plates 6 are arranged at intervals, and the innermost side of the plurality of nested annular low plates 5 and annular high plates 6 is the annular low plate 5, and the highest end of the annular low plate 5 is lower than the highest end of the annular high plate 6, a sewage outlet 7 is arranged above the side wall of the tank body 1, a water outlet 8 is arranged below the side wall of the tank body 1, and a water inlet pipe 9 is arranged at the bottom of the tank body 1, and the height of the sewage outlet 7 does not exceed the highest end of the annular high plate 6 The water outlet 8 is located above the partition 2, the water inlet pipe 9 passes through the dissolved air cavity 3 and is connected to the inner side of the innermost annular low plate 5, a plurality of connecting ports 10 are provided at the bottom end of the annular high plate 6, a U-shaped sewage skimming pipe 11 is provided at the sewage outlet 7, the sewage skimming pipe 11 extends from the sewage outlet 7 and fits to the innermost annular low plate 5, a plurality of groups of sewage skimming ports 12 are provided on the sewage skimming pipe 11, and the plurality of groups of sewage skimming ports 12 are distributed in the compartment between the outer side of the annular low plate 5 and the annular high plate 6, and a plurality of dissolved air release holes 13 are provided on the partition 2; the liquid to be treated enters the inner side of the annular low plate 5 through the water inlet pipe 9, overflows from the highest point of the annular low plate 5 into the inner side of the adjacent annular high plate 6, and then enters the inner side of the next adjacent annular low plate 5 through the connecting port 10, circulates in sequence and finally flows out from the water outlet 8.

[0049] The liquid to be treated circulates up and down between the multiple annular low plates 5 and the annular high plates 6, which increases the adhesion time of oil droplets, impurity flocs and microbubbles. Each time the liquid to be treated circulates up and down, the skimming port 12 skims off floating oil and impurities. After multiple stages of impurity skimming, the contaminant content of the liquid to be treated will be greatly reduced.

[0050] Specifically, in this embodiment, an annular low plate 5, an annular high plate 6, and an annular low plate 5 are arranged from the inside to the outside in the tank body 1, and compartments 1, 2, 3, and 4 are formed from the inside to the outside in the tank body 1. The liquid to be treated, such as oil produced water, flows into the bottom of compartment 1 from the water inlet pipe 9, overflows into compartment 2 through the top of the annular low plate 5, flows into compartment 3 through multiple connecting ports 10 at the bottom end of the annular high plate 6, and then overflows into compartment 4 through the top of the annular low plate 5, and flows out through the water outlet at the bottom of compartment 4. When the treated liquid flows out from the outlet 8 and flows into the compartment 2 and the compartment 4, the skimming outlet 12 located above the compartment 2 and the compartment 4 will skim off the dirty oil and impurities floating on the liquid; it can be understood that the number of the annular low plate 5 and the annular high plate 6 is not limited to the number shown in the figure, and the number of the annular low plate 5 and the annular high plate 6 can be increased, and they can be arranged at intervals to form more compartments, and the same number of skimming outlets 12 can be used to achieve more levels of impurity skimming, so that the pollution content of the treated liquid will be greatly reduced

[0051] Reference Figure 3The tops of the several annular low plates 5 are all provided with an inwardly inclined annular inclined weir 14, and the heights of the several annular inclined weirs 14 decrease from the inside to the outside.

[0052] Specifically, due to the flow direction of the liquid from the inside to the outside, the liquid level in the inner compartment is higher than the liquid level in the outer compartment, and the height of the inclined weir is successively reduced to adapt to the successively lowered liquid level.

[0053] By setting the annular inclined weir 14, when the liquid to be treated flows out from the upper end of the annular low plate 5, the flow velocity of the liquid to be treated in the compartment is increased, which promotes pollutants such as hydrocarbons lighter than water to rise to the surface of the compartment, while the cleaner and therefore heavier water is pushed toward the bottom of the tank body 1.

[0054] Reference Figure 3 The heights of the plurality of sewage skimming ports 12 decrease from the inside to the outside, and the sewage skimming ports 12 in the same compartment have the same height.

[0055] Specifically, due to the flow direction of the liquid from the inside to the outside, the liquid level in the inner compartment is higher than the liquid level in the outer compartment, and the height of the skimming port 12 is successively reduced to adapt to the successively lowering liquid level, thereby realizing multi-stage skimming of impurities; it can be understood that if the number of the annular low plate 5 and the annular high plate 6 is increased, the corresponding number of the skimming ports 12 should also be increased, and the height of the skimming ports 12 is successively reduced from the inside to the outside.

[0056] By providing successively lowered pollutant skimming ports 12, multi-stage impurity skimming can be achieved, and the pollutant content of the liquid to be treated can be greatly reduced.

[0057] Reference Figure 3 In this embodiment, the bottom edge of the dirt-skimming port 12 is configured to be wavy.

[0058] By providing the bottom edge of the skimming port 12 in a wave shape, unwanted impurities are facilitated to enter the skimming pipe 11 .

[0059] It is understandable that the bottom edge of the dirt-skimming port 12 may also be a sawtooth shape, an arc shape, or other shapes that increase the length of the bottom edge.

[0060] Reference Figure 3 A plurality of balancing holes 15 are vertically arranged on the annular high plate 6 and the annular low plate 5 , and the positions of the balancing holes 15 on adjacent annular high plates 6 and annular low plates 5 are offset.

[0061] In this embodiment, the balancing hole 15 is arranged in an arc shape, and two rows of balancing holes 15 are arranged in symmetrical positions on an annular high plate 6 or annular low plate 5, and the balancing holes 15 on the annular high plate 6 and the annular low plate 5 at adjacent positions are offset from each other by 90°; it can be understood that in other embodiments, the balancing hole 15 can be of any shape, and its size should not be too large, so that a small amount of liquid can pass through the balancing hole 15, and the balancing holes 15 on the annular high plate 6 and the annular low plate 5 at adjacent positions are not in the same position, which is used to maintain the relative balance of the liquid levels in adjacent compartments.

[0062] By providing the balancing holes 15, equalization of the liquid levels in these adjacent compartments is allowed, avoiding short-circuiting of liquid in adjacent compartments without significantly reducing the contaminant content; avoiding short-circuiting of liquid through the tank increases the residence time in the tank, allowing more contaminants to be skimmed from the top of the liquid in each compartment.

[0063] Reference Figure 6 The water inlet pipe 9 extends to the top of the partition 2, and the top of the water inlet pipe 9 is covered with a cover plate 16. The part of the water inlet pipe 9 above the partition 2 is provided with a water inlet hole 17, and the partition 2 below the cover plate 16 is annularly distributed with dissolved gas release holes 13.

[0064] Specifically, a narrow gap is formed between the cover plate 16 and the annular lower plate 5, and microbubbles float up and the liquid passes through the gap at the same time. The microbubbles are pressurized by the air dissolving pump to enter the air dissolving tank, and the air is mixed into the air dissolving tank to dissolve the air in the water to the maximum extent to form air-saturated water, which is transported to the air dissolving cavity 3 through the air dissolving pipe 4, flows through the air dissolving release hole 13 and suddenly reduces the pressure to generate nanometer-scale microbubbles. After contacting the liquid in the compartment, the oil, water and solid suspended matter are separated, and the oil is collected by the skimming pipe 11 and discharged out of the tank, so as to ensure the continuous and efficient operation of the air flotation in the tank body 1.

[0065] When the liquid to be treated passes through the slit formed by the cover plate 16, it fully merges with the microbubbles released from the dissolved gas release holes 13. The arrangement of introducing bubbles or microbubbles in a narrow area increases the possibility of contact or adhesion with pollutants in the fluid.

[0066] Reference Figure 6 A plant-shaped block 18 is arranged between the outer side of the annular low plate 5 and the inner side of the annular high plate 6, and dissolved gas release holes 13 are distributed in an annular manner on the partition plate 2 below the plant-shaped block 18.

[0067] Specifically, the factory-shaped block 18 is an annular block that is wide at the top and narrow at the bottom, and is used to form a slit above the dissolved gas release hole 13 .

[0068] When the treated liquid passes through the slit formed by the factory-shaped block 18, it fully merges with the microbubbles released from the dissolved gas release holes 13. The arrangement of introducing bubbles or microbubbles in a narrow area increases the possibility of contact or adhesion with pollutants in the fluid.

[0069] Reference Figure 6 The outermost factory-shaped block 18 is higher than the sewage outlet 7.

[0070] The liquid to be treated is made to flow out after passing through the slit formed by the factory-shaped block 18. The arrangement of introducing bubbles or microbubbles into the narrow area increases the possibility of contact or adhesion with pollutants in the fluid.

[0071] Example 2, reference Figure 8 , which is a second embodiment of the present invention, provides: an oil-water deep separation process for petrochemical oil refining, using a flotation system composed of an oil-water deep separation device for petrochemical oil refining, comprising the following steps:

[0072] Step 1: Pre-treat the oil-water mixture by coarse filtration or sedimentation to remove larger suspended particles and impurities;

[0073] Step 2: Add appropriate amount of chemical agents, such as flocculants and demulsifiers, to the pretreated mixed liquor to promote the aggregation of oil droplets to form larger flocs, which is a key step to prepare for subsequent separation;

[0074] Step 3: Use high-speed cyclone technology of a cylindrical cyclone tube to evenly stir and mix the mixed liquid with the added reagent. This process promotes further aggregation of oil droplets and preliminarily separates a portion of oil and water;

[0075] Step 4: using an air dissolving pump to dissolve air in the treated water to form high-concentration air-dissolved water, ready for use in the tank 1;

[0076] Step 5: Introduce dissolved gas water into the tank 1, quickly reduce the pressure to release the dissolved gas, generate a large number of tiny bubbles, the microbubbles combine with oil droplets and impurity flocs in the water, adhere to each other under the action of surface tension, and form flocs with greater buoyancy;

[0077] Step 6: a circulating flow is set in the tank 1 to prolong the contact time and path of the oil droplets and impurity flocs with the microbubbles by increasing the rotational motion of the liquid;

[0078] Step 7: The oil droplets and adhering floccules quickly float to the water surface under the action of Archimedean buoyancy, thereby being separated from the clean water, and the oil layer and floccules floating on the surface are removed through the skimmer pipe 11;

[0079] Step 8: The clean water after deep treatment is discharged from the bottom of the tank 1 and is sent to the next process stage or reused after quality inspection.

[0080] Through these steps, the oil and impurities in the oil-water mixture are effectively separated, which can meet the needs of efficient wastewater treatment in the petrochemical refining process.

[0081] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. An oil-water deep separation device for petrochemical oil refining, comprising a tank body (1), characterized in that: The tank body (1) further comprises a partition (2) arranged at the lower part of the tank body (1), a gas dissolving chamber (3) being formed between the partition (2) and the bottom of the tank body (1), a gas dissolving pipe (4) being arranged on the tank body (1) and communicating with the gas dissolving chamber (3), a plurality of nested annular low plates (5) and annular high plates (6) being arranged above the partition (2), the annular low plates (5) and the annular high plates (6) being arranged at intervals, the innermost of the plurality of nested annular low plates (5) and annular high plates (6) being the annular low plate (5), the highest end of the annular low plate (5) being lower than the highest end of the annular high plate (6), a sewage outlet (7) being arranged above the side wall of the tank body (1), a water outlet (8) being arranged below the side wall of the tank body (1), a water inlet pipe (9) being arranged at the bottom of the tank body (1), the height of the sewage outlet (7) not exceeding the highest point of the annular high plate (6), the water outlet (8) being located on the partition (2) and the lower part of the annular high plate (6). The water inlet pipe (9) passes through the gas dissolving chamber (3) and is connected to the inner side of the innermost annular low plate (5); the bottom end of the annular high plate (6) is provided with a plurality of connection ports (10); the sewage outlet (7) is provided with a U-shaped sewage skimming pipe (11); the sewage skimming pipe (11) extends from the sewage outlet (7) and is attached to the innermost annular low plate (5); the sewage skimming pipe (11) is provided with a plurality of groups of sewage skimming ports (12); the plurality of groups of sewage skimming ports ( 12) are distributed in the compartment between the outer side of the annular low plate (5) and the annular high plate (6), and a plurality of dissolved gas release holes (13) are arranged on the partition (2); the liquid to be treated enters the inner side of the annular low plate (5) from the water inlet pipe (9), overflows from the highest point of the annular low plate (5) into the inner side of the adjacent annular high plate (6), and then enters the inner side of the next adjacent annular low plate (5) through the connecting port (10), circulates in sequence, and finally flows out from the water outlet (8); The top ends of the plurality of annular low plates (5) are all provided with an annular inclined weir (14) inclined inwardly, and the heights of the plurality of annular inclined weirs (14) decrease sequentially from the inside to the outside; The heights of the plurality of sewage skimming ports (12) decrease in sequence from the inside to the outside, the sewage skimming ports (12) in the same compartment have the same height, and the bottom edge of the sewage skimming port (12) is arranged in a wave shape.

2. The oil-water deep separation device for petrochemical oil refining according to claim 1, characterized in that: A plurality of balancing holes (15) are vertically arranged on the annular high plate (6) and the annular low plate (5), and the positions of the balancing holes (15) on adjacent annular high plates (6) and annular low plates (5) are offset.

3. The oil-water deep separation device for petrochemical oil refining according to claim 1 is characterized in that: The water inlet pipe (9) extends to above the partition (2), the water inlet pipe (9) is covered with a cover plate (16), the part of the water inlet pipe (9) above the partition (2) is provided with a water inlet hole (17), and the partition (2) below the cover plate (16) is provided with the dissolved gas release holes (13) in an annular arrangement.

4. The oil-water deep separation device for petrochemical oil refining according to claim 1 is characterized in that: A plant-shaped block (18) is arranged between the outer side of the annular lower plate (5) and the inner side of the annular higher plate (6), and the dissolved gas release holes (13) are distributed in an annular manner on the partition plate (2) below the plant-shaped block (18).

5. The oil-water deep separation device for petrochemical oil refining according to claim 4 is characterized in that: The height of the plant-shaped block (18) located at the outermost side is higher than the sewage outlet (7).

6. A deep oil-water separation process for petrochemical oil refining, using an air flotation system composed of the deep oil-water separation device for petrochemical oil refining as claimed in claim 1, characterized in that: The following steps are involved: Step 1: Pre-treat the oil-water mixture by coarse filtration or sedimentation to remove larger suspended particles and impurities; Step 2: Add flocculants or demulsifiers to the pretreated mixed liquor to promote the aggregation of oil droplets to form larger flocs, which is a key step to prepare for subsequent separation; Step 3: Use high-speed cyclone technology of a cylindrical cyclone tube to evenly stir and mix the mixed liquid with the added reagent. This process promotes further aggregation of oil droplets and preliminarily separates a portion of oil and water; Step 4: using an air dissolving pump to dissolve air in the treated water to form high-concentration air-dissolved water, ready for use in the tank (1); Step 5: introducing dissolved gas water into the tank (1), rapidly reducing pressure to release dissolved gas, generating a large number of tiny bubbles, which combine with oil droplets and impurity flocs in the water, adhere to each other under the action of surface tension, and form flocs with greater buoyancy; Step 6: a circulating flow is set in the tank (1) to prolong the contact time and path of the oil droplets and impurity flocs with the microbubbles by increasing the rotational motion of the liquid; Step 7: The oil droplets and adhering floccules quickly float to the water surface under the action of Archimedean buoyancy, thereby being separated from the clean water, and the oil layer and floccules floating on the surface are removed through the skimmer pipe (11); Step 8: The clean water after deep treatment is discharged from the bottom of the tank (1) and is sent to the next process stage or reused after quality inspection.

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