Coalescence filtering tank for oil-containing wastewater treatment

Abstract

The invention discloses a coalescence filtering tank for oily wastewater treatment, relates to the technical field of filtering tanks, and solves the technical problems that in the oily wastewater treatment process, when more oily wastewater exists, the wastewater treatment capacity of a single filtering area is small, and filtering is not thorough. Comprising a tank body, and the interior of the tank body is sequentially divided into a first left filtering area, a middle pretreatment area and a second right filtering area from left to right; the middle pretreatment area comprises a swirler vertically mounted in the middle of the tank body, a plurality of groups of separating inclined plates for separating oil and water are arranged above the swirler, and water separated from the middle pretreatment area enters the left filtering area I and the right filtering area II respectively; through a first mode of oil-water treatment through cooperation of the left filtering area I, the middle pretreatment area and the right filtering area II, a filtering treatment process is added, multi-stage filtering treatment on wastewater can be realized, the treatment effect on the oil-containing wastewater is improved, and the treated water quality index is ensured to be qualified.

Description

Technical Field

[0001] The invention belongs to the technical field of filter tanks, in particular to a coalescence filter tank for treating oily wastewater. Background Art

[0002] Oily wastewater is a type of wastewater generated during oil extraction and production. Oily wastewater has complex components, high oil content and high mineralization. If it is directly reinjected without treatment, it will cause equipment damage and pipeline or formation blockage, affecting production safety; if it is directly discharged into the soil, it will affect the activity of soil microorganisms and also pollute water bodies and the atmosphere. Therefore, filter tanks are used to purify oily wastewater.

[0003] In the process of treating oily wastewater with some existing filter tanks, when the oil content of the wastewater is high, the filter bed and filter element are easily contaminated and clogged, and it is difficult to restore the performance of the filter material and filter element through backwashing; when the incoming water volume suddenly increases, the single filter area cannot meet the production requirements, the pressure is high, and the filtration is not clean; when the filter element is dirty, it is necessary to stop the operation and replace the filter element. Only after the replacement is completed, the filter can treat the oily wastewater again, which leads to the problem of high shutdown costs. Summary of the invention

[0004] The present invention aims to solve at least one of the technical problems existing in the prior art; to this end, the present invention provides a coalescing filter tank for treating oily wastewater.

[0005] A coalescing filter tank for treating oily wastewater, comprising: A tank body, wherein the interior of the tank body is divided into a left filtering zone 1, a middle pre-treatment zone and a right filtering zone 2 from left to right; The middle pretreatment area includes a cyclone installed vertically in the middle position of the tank body, and a plurality of separation inclined plates for oil-water separation are arranged above the cyclone. The water separated from the middle pretreatment area enters the left filter zone 1 and the right filter zone 2 respectively, and is filtered and processed by the filter beds and filter elements arranged in the left filter zone 1 and the right filter zone 2.

[0006] Preferably, the middle pretreatment zone further comprises a first water inlet arranged on the front surface of the tank body, and the rear end of the first water inlet is communicated with the cyclone and supplies water to the interior of the cyclone.

[0007] Preferably, the middle pretreatment zone further comprises a partition plate horizontally mounted on the inner wall of the tank body and located at the upper end of the cyclone, and a small number of water delivery holes are opened on the upper surface of the partition plate.

[0008] Preferably, a wastewater cavity is formed between the cyclone, the baffle and the inner wall of the tank body, and a first water outlet communicating with the water cavity is provided at the bottom of the tank body.

[0009] Preferably, the left filter zone 1 and the right filter zone 2 have the same structure, and the left filter zone 1 includes: A filter bed is horizontally installed inside the tank body, wherein a guide inclined plate is provided inside the tank body below the filter bed, and a water storage cavity is formed between the lower surface of the guide inclined plate and the inner wall of the tank body; A second water inlet installed on the upper surface of the left end of the tank body, a left water pipe is provided between the second water inlet and the first water outlet; A third water inlet is installed on the upper surface of the right end of the tank body, and a right water pipe is arranged between the third water inlet and the first water outlet; and two groups of filter elements longitudinally distributed between the lower side of the guide inclined plate and the inner wall of the tank body.

[0010] Preferably, a plurality of water holes are provided on the surface of the guide inclined plate, and a second water outlet communicating with the filter element is provided on the lower surface of the left end of the tank body; The lower surface of the right end of the tank body is provided with a third water outlet communicated with the filter element.

[0011] Preferably, the left first filtering zone further comprises a water distribution pipe located above the filter bed, the water distribution pipe is connected to the second water inlet, and a plurality of water distribution ports are evenly opened on the surface of the water distribution pipe.

[0012] Preferably, a flushing structure for cleaning filter media in the filter bed is provided inside the left first filter zone and the right second filter zone, and the flushing structure includes: A scrubbing bucket for cleaning the filter material; A material distribution barrel extending above the filter bed, the material distribution barrel presents a Y shape, and a material distribution opening at the lower end thereof extends toward both ends of the filter bed; Control the left electric valve 1 and the right electric valve 2 of the scrubbing bucket filter material to enter the cloth bucket; And a backwash discharge port is installed at the bottom of the tank body, and the backwash discharge port is located between the two guide inclined plates.

[0013] Preferably, the flushing structure also includes a sewage pipe connected to the interior of the scrubbing bucket, and a valve nine is provided on the sewage pipe.

[0014] Preferably, an oil collecting device is provided on the top of the tank body and is connected with the left filtering zone 1, the middle pretreatment zone and the right filtering zone 2 respectively. An oil-water interface meter is provided on the top of the oil collecting device, and oil collecting pipes are provided between the multiple oil collecting devices.

[0015] Compared with the prior art, the present invention has the following beneficial effects: (1) The present invention adds a middle pretreatment zone to the left filter zone 1 and the right filter zone 2, and can remove most of the oil pollution in the oily wastewater through the cyclone, thereby reducing the pollution of the rear filter bed and filter element by the oil pollution.

[0016] (2) The present invention adopts the first method of treating oil and water by combining the left filtering zone 1, the middle pretreatment zone and the right filtering zone 2, thereby adding a filtering treatment process, thereby realizing multi-stage filtering treatment of wastewater, improving the treatment effect and cleanliness of oily wastewater, and ensuring that the treated water quality indicators are qualified.

[0017] (3) The second method of the present invention for treating oil and water is to coordinate the middle pre-treatment zone with the left first filter zone and the right second filter zone. The wastewater treatment capacity is large and emergency treatment of a sudden increase in wastewater at the front end can be achieved.

[0018] (4) The present invention adopts a third method of treating oil and water by cooperating the left filter zone 1, the middle pretreatment zone and the right filter zone 2. When the filter element in the left filter zone 1 or the right filter zone 2 is dirty and needs to be replaced, the left filter zone 1 or the right filter zone 2 can work independently to ensure the continuous treatment of the oily wastewater without the trouble of stopping the entire filter tank to replace the filter element, thereby reducing the shutdown cost and improving the continuous filtration or treatment effect of the oily wastewater.

[0019] (5) The present invention adopts the fourth method of treating oil and water by cooperating the left filter zone 1, the middle pretreatment zone and the right filter zone 2. When the filter material in the left filter zone 1 is cleaned, the wastewater in the middle pretreatment zone first enters the left filter zone 1 for filtration through the first water outlet, and the filtered water in the left filter zone 1 enters the right filter zone 2 for filtration through the second water outlet, thereby realizing the simultaneous cleaning of the filter material and multi-stage treatment, and realizing the efficient treatment of oily wastewater.

[0020] (6) The present invention adopts the fifth method of treating oil and water by cooperating the left filter zone 1, the middle pretreatment zone and the right filter zone 2. When the filter media in the right filter zone 2 is cleaned, the wastewater in the middle pretreatment zone first enters the right filter zone 2 for filtration through the first water outlet, and the filtered water in the right filter zone 2 enters the left filter zone 1 for filtration through the third water outlet, thereby realizing the simultaneous cleaning of the filter media and multi-stage treatment, and realizing the efficient treatment of oily wastewater. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a structural schematic diagram of the wastewater treatment process of the filter tank of the present invention; Figure 2 For the present invention Figure 1 Schematic diagram of the structure of the central pretreatment area; Figure 3 For the present invention Figure 1 A magnified image of area A; Figure 4 For the present invention Figure 1 Schematic diagram of the structure of the central water pipe; Figure 5 For the present invention Figure 1 Structural schematic diagram of the middle flushing structure; In the figure: 1. tank body; 2. cyclone; 3. first water inlet; 4. partition; 5. separation inclined plate; 6. first water outlet; 7. right water pipe; 8. second water outlet; 9. filter element; 10. left water pipe; 11. guide inclined plate; 12. filter bed; 13. second water inlet; 14. sewage pipe; 15. oil collecting pipe; 16. oil-water interface instrument; 17. flushing structure; 18. sewage outlet; 19. water distribution pipe; 20. backwash outlet; 21. scrubbing bucket; 22. distribution bucket; 23. valve eight; 24. valve six; 25. valve three; 26. valve five; 27. valve seven; 28. valve nine; 29. ​​valve thirteen; 30. valve one; 31. valve two; 32. valve four; 33. third water inlet; 34. third water outlet; 35. electric valve one; 36. electric valve two. DETAILED DESCRIPTION

[0022] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0023] Embodiment 1 See also Figure 1 - Figure 3 The present application provides a coalescing filter tank for treating oily wastewater, comprising: Tank body 1, the interior of tank body 1 is divided into left filtration zone 1, middle pretreatment zone and right filtration zone 2 from left to right; The middle pretreatment zone includes a cyclone 2 vertically installed in the middle position of the tank body 1. A plurality of separation inclined plates 5 for oil-water separation are arranged above the cyclone 2. Wastewater enters the cyclone 2 through the first water inlet 3. The cyclone 2 is used to facilitate rapid separation of oil and water. The oil flows out from the middle upper part of the cyclone 2 and is then dehydrated by the separation inclined plate 5. The water separated from the middle pretreatment zone enters the left filter zone 1 and the right filter zone 2 respectively, and is filtered and processed by the filter beds 12 arranged in the left filter zone 1 and the right filter zone 2. The middle pretreatment zone also includes a first water inlet 3 arranged on the front surface of the tank body 1. The rear end of the first water inlet 3 is connected to the cyclone 2 and supplies water to the inside of the cyclone 2.

[0024] In this embodiment, preferably, the middle pretreatment zone also includes a partition 4 horizontally installed on the inner wall of the tank body 1 and located at the upper end of the cyclone 2. The water on the separation inclined plate 5 can flow downward along its inclined surface and fall into the wastewater chamber through the water delivery holes. A small number of water delivery holes are opened on the upper surface of the partition 4. The setting of the water delivery holes can ensure that when the incoming liquid fluctuates, the upper separation inclined plate 5 is not impacted, which makes it convenient for the wastewater separated by the separation inclined plate 5 to re-enter the wastewater chamber, thereby improving the wastewater oil removal effect.

[0025] In this embodiment, preferably, a wastewater cavity is formed between the cyclone 2, the partition 4 and the inner wall of the tank body 1, and a first water outlet 6 communicating with the water cavity is provided at the bottom of the tank body 1 to facilitate the discharge of the pretreated wastewater.

[0026] In summary, the incoming water first enters the cyclone 2 through the first water inlet 3. In the cyclone 2, the water moves downward and flows out from the lower part of the cyclone 2, and the oil flows out from the upper part of the cyclone 2, and then passes through the separation inclined plate 5 for dehydration. The oil moves upward along the separation inclined plate 5 and is collected by the oil collecting device, while the water on the separation inclined plate 5 flows downward along the inclined surface and passes through the water delivery hole on the partition 4 into the wastewater cavity. The left filter zone 1, the middle pretreatment zone and the right filter zone 2 cooperate with the first method of oil-water treatment. The water flowing out from the lower part of the cyclone 2 enters the wastewater cavity, and then is discharged from the first water outlet 6, passes through the valve 2 31 and the left water pipe 10 to enter the second water inlet 13 in the left filter zone 1, and passes through the water distribution pipe The water outlet on 19 falls on the filter bed 12 and is filtered by the filter material in the filter bed 12. The wastewater after preliminary filtration passes through the guide inclined plate 11 and enters the filter element 9 for treatment. The purified water after filtration by the filter element 9 passes through valve five 26, and then passes through valve four 32 and the extended drain pipe to enter the second water inlet 13 of the right filter zone 2, and then flows downward after being filtered by the filter bed 12 on the right. After being filtered by the guide inclined plate 11 and the filter element 9 on the right, the purified water of the second purification is transported outward through valve eight 23. The first method adds a filtration treatment process, which can realize multi-stage filtration treatment of wastewater, improve the treatment effect and cleanliness of oily wastewater, and ensure that the treated water quality indicators are qualified.

[0027] In summary, the incoming water first enters the cyclone 2 through the first water inlet 3. In the cyclone 2, the water moves downward and flows out from the lower part of the cyclone 2, and the oil flows out from the upper part of the cyclone 2, and then passes through the separation inclined plate 5 for dehydration. The oil moves upward along the separation inclined plate 5 and is collected by the oil collecting device, while the water on the separation inclined plate 5 flows downward along the inclined surface and passes through the water delivery hole on the partition plate 4 into the wastewater cavity. The middle pretreatment zone cooperates with the left filter zone 1 and the right filter zone 2 to treat the oil and water in the second way. The water flowing out from the lower part of the cyclone 2 enters the wastewater cavity and is then discharged from the first water outlet 6. The wastewater enters the second water inlet 13 in the left filter zone 1 and the third water inlet 33 in the right filter zone 2 in parallel through valve 1 30, valve 2 31 and the left water pipe 10 and the right water pipe 7, and falls on the filter bed 12 through the water distribution port on the water distribution pipe 19, and is filtered and processed by the filter material in the filter bed 12. The wastewater after preliminary filtration passes through the guide inclined plate 11 and enters the filter element 9 for processing. The purified water after filtration by the filter element 9 can be transported out through valve 7 27 and valve 8 23. The second method has a large wastewater treatment capacity and can realize emergency treatment of sudden increase in wastewater at the front end.

[0028] Embodiment 2 Reference Figure 1 , Figure 4 and Figure 5, which is the second embodiment of the present invention.

[0029] In this embodiment, preferably, the left filter zone 1 and the right filter zone 2 have the same structure, and the left filter zone 1 includes: A filter bed 12 is horizontally installed inside the tank body 1, and a guide inclined plate 11 is provided inside the tank body 1 below the filter bed 12, and a water storage cavity is formed between the lower surface of the guide inclined plate 11 and the inner wall of the tank body 1; The second water inlet 13 installed on the upper surface of the left end of the tank body 1 is convenient for sending the wastewater discharged from the central pre-treatment area to the left filtration area 1 for treatment. A left water pipe 10 is arranged between the second water inlet 13 and the first water outlet 6. A valve 2 31 is arranged on the left water pipe 10. The left and right bottoms of the tank body 1 are both provided with sewage outlets 18; A third water inlet 33 is installed on the upper surface of the right end of the tank body 1, and a right water pipe 7 is arranged between the third water inlet 33 and the first water outlet 6; And four groups of filter elements 9 are longitudinally distributed between the lower side of the guide inclined plate 11 and the inner wall of the tank body 1 . The filter element 9 can be configured to be pull-out from outside the body as required, so as to facilitate replacement and cleaning of the filter element 9 .

[0030] In this embodiment, preferably, a plurality of water holes are opened on the surface of the guide inclined plate 11 to facilitate water to enter the filter element 9 for processing, a second water outlet 8 communicating with the filter element 9 is arranged on the lower surface of the left end of the tank body 1, a third water outlet 34 communicating with the filter element 9 is arranged on the lower surface of the right end of the tank body 1, a left water pipe 10 is arranged between the first water outlet 6 and the second water inlet 13 on the left, and a right water pipe 7 is arranged between the first water outlet 6 and the third water inlet 33 on the right. A valve two 31 is provided on the left water pipe 10, a valve one 30 is provided on the right water pipe 7, the second water outlet 8 and the third water outlet 34 are both connected to drain pipes, valve seven 27 and valve eight 23 are provided on the two drain pipes respectively, two branch pipes are connected to the left water pipe 10 and the right water pipe 7 respectively, valve four 32 and valve three 25 are provided on the two branch pipes respectively, connecting water pipes are provided between the two branch pipes and the two drain pipes respectively, and valve five 26 and valve six 24 are provided on the two connecting water pipes.

[0031] In the present embodiment, preferably, the left filter zone 1 also includes a water distribution pipe 19 located above the filter bed 12, the water distribution pipe 19 is connected to the second water inlet 13, and a plurality of water distribution ports are evenly opened on the surface of the water distribution pipe 19, so as to facilitate uniform water distribution to the filter bed 12 and facilitate sufficient filtering and treatment of the wastewater by the filter bed 12.

[0032] In summary, the left filter zone 1, the middle pretreatment zone and the right filter zone 2 cooperate in three ways of treating oil and water. When the filter element 9 in the left filter zone 1 is replaced, the right filter zone 2 works. The specific working process is that the water flowing out from the lower part of the cyclone 2 enters the wastewater chamber, and then enters the third water inlet 33 of the right filter zone 2 from the right water pipe 7 and valve 1 30 connected to the first water outlet 6, flows downward after being filtered by the filter material of the right filter bed 12, and the purified water after being filtered by the filter element 9 is transported outward through the valve 8 23; when the filter element 9 in the right filter zone 2 is replaced, the water in the right filter zone 2 is replaced. During replacement, the left filter zone 1 works. The specific working process is that the water flowing out from the lower part of the cyclone 2 enters the wastewater chamber, and then enters the second water inlet 13 of the left filter zone 1 through the left water pipe 10 and valve 1 30 connected to the first water outlet 6, flows downward after being filtered by the filter material of the left filter bed 12, and the purified water after being filtered by the filter element 9 is transported outward through valve 7 27; at this time, the continuous treatment of the oily wastewater can be guaranteed, and there will be no trouble of stopping work to replace the filter element 9, which reduces the shutdown cost and improves the filtration continuity or treatment effect of the oily wastewater.

[0033] Embodiment 3 Reference Figure 5 , which is the third embodiment of the present invention.

[0034] In this embodiment, preferably, a flushing structure 17 for cleaning the filter material in the filter bed 12 is provided inside the left filter zone 1 and the right filter zone 2. The flushing structure 17 includes: A scrubbing bucket 21 for cleaning the filter material, the scrubbing bucket 21 cleans the filter material, and a pipeline is connected to the scrubbing bucket 21, and a valve 28 is provided on the pipeline; A material barrel 22 extending above the filter bed 12 is Y-shaped, and a material opening at the lower end thereof extends toward both ends of the filter bed 12, so as to facilitate the refilling of the filter bed 12 with filter material, and the filter material has a large distribution range and will not gather in the middle of the filter bed 12; The left electric valve 1 35 and the right electric valve 2 36 control the filter material of the scrubbing barrel 21 to enter the cloth barrel 22; And a backwash discharge port 20 installed at the bottom of the tank body 1 , the backwash discharge port 20 can pass cleaning water and filter material into the scrubbing bucket 21 , and the backwash discharge port 20 is located between the two guide inclined plates 11 .

[0035] In this embodiment, preferably, the flushing structure 17 also includes a sewage pipe 14 communicated with the interior of the scrubbing bucket 21 to facilitate sewage discharge.

[0036] In this embodiment, preferably, an oil collecting device is provided on the top of the tank body 1, which is connected with the left filtering zone 1, the middle pretreatment zone and the right filtering zone 2 respectively, an oil-water interface meter 16 is provided on the top of the oil collecting device, and oil collecting pipes 15 are provided between the multiple oil collecting devices, and valves are provided on the oil collecting pipes 15 on the top of the multiple oil collecting devices.

[0037] In summary, the left filter zone 1, the middle pretreatment zone and the right filter zone 2 cooperate with the four methods of oil-water treatment. When the filter bed 12 in the left filter zone 1 is dirty and needs to be cleaned, the left filter zone 1 and the right filter zone 2 work in series. The specific working process is that the water flowing out from the lower part of the cyclone 2 enters the wastewater chamber, and then enters the second water inlet 13 of the left filter zone 1 through the first water outlet 6 through the valve 2 31, and flows downward after being filtered by the filter material in the left filter bed 12. The filtered water is then filtered by the filter element 9 and enters the purification chamber. The purified water in the left filter zone 1 enters the third water inlet 13 through the valve 5 26 and the valve 3 25. The water flows downward after being filtered by the filter material in the left filter bed 12, and the filtered water enters the purification chamber after being filtered by the filter element 9, and the purified water is transported outward through the valve eight 23; later, the valve nine 28 is opened, and the filter material in the lower funnel is pressed into the upper scrubbing bucket 21 under the action of water pressure, and the filter material is scrubbed under the action of detergents, bactericides and other agents, and the sewage is discharged from the valve nine 28 on the upper part of the scrubbing bucket 21. After the filter material is cleaned, the valve nine 28 is closed, the electric valve one 35 at the lower part of the scrubbing bucket 21 is opened, and the cloth bucket 22 falls into the filter bed 12 to complete the filter material cleaning work.

[0038] The left filter zone 1, the middle pretreatment zone and the right filter zone 2 cooperate in five ways of treating oil and water. When the filter bed 12 in the right filter zone 2 is dirty and needs to be cleaned, the right filter zone 2 works in series with the left filter zone 1. The specific working process is that the water flowing out from the lower part of the cyclone 2 enters the wastewater chamber, and then enters the third water inlet 33 of the right filter zone 2 from the first water outlet 6 through the valve 1 30, flows downward after being filtered by the filter material in the left filter bed 12, and the filtered water enters the purification chamber after being filtered by the filter element 9. The purified water in the right filter zone 2 enters the second water inlet through the valve 6 24 and the valve 4 32. 13, after being filtered by the filter material in the left filter bed 12, it flows downward, and the filtered water is filtered by the filter element 9 and then enters the purification chamber, and the purified water is transported outward through the valve seven 27; later, the valve thirteen 29 is opened, and the filter material in the lower funnel is pressed into the upper scrubbing bucket 21 under the action of water pressure, and the filter material is scrubbed under the action of detergents, bactericides and other agents, and the sewage is discharged from the valve thirteen 29 on the upper part of the scrubbing bucket 21. After the filter material is cleaned, the valve thirteen 29 is closed, the electric valve two 36 at the lower part of the scrubbing bucket 21 is opened, and the cloth bucket 22 falls into the filter bed 12 to complete the filter material cleaning work.

[0039] Embodiment 4 This embodiment is obtained by combining the first embodiment, the second embodiment and the third embodiment.

[0040] During use, in order to ensure that the treated water quality indicators are qualified, the left filter zone 1, the middle pretreatment zone and the right filter zone 2 are allowed to work together at the same time, which can extend the treatment time of the wastewater and increase the filtering steps. Multi-stage filtration improves the treatment effect of oily wastewater. When the amount of oily wastewater is large, the middle pretreatment zone is allowed to work in parallel with the left filter zone 1 and the right filter zone 2 to achieve emergency treatment of sudden increase in front-end wastewater. When the filter element 9 on either side needs to be replaced, the filter element 9 on the other side continues to work to ensure continuous treatment of the oily wastewater. The entire filter tank will not be shut down for cleaning, reducing the cost of shutdown and improving the efficiency of oily wastewater treatment.

[0041] The above embodiments are only used to illustrate the technical method 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 method of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical method of the present invention.

Claims

1. A coalescing filter tank for treating oily wastewater, characterized in that: include: A tank body (1), wherein the interior of the tank body (1) is divided into a left filtering zone 1, a middle pre-treatment zone and a right filtering zone 2 from left to right; The middle pretreatment zone comprises a cyclone (2) vertically mounted in the middle of the tank body (1), and a plurality of separation inclined plates (5) for oil-water separation are arranged above the cyclone (2). Water separated from the middle pretreatment zone enters the left first filter zone and the right second filter zone respectively, and is filtered and processed by the filter beds (12) arranged in the left first filter zone and the right second filter zone; The left filter zone 1 and the right filter zone 2 have the same structure, and the left filter zone 1 includes: A filter bed (12) is horizontally mounted inside a tank body (1), wherein a guide inclined plate (11) is disposed inside the tank body (1) and is located below the filter bed (12), and a water storage cavity is formed between a lower surface of the guide inclined plate (11) and an inner wall of the tank body (1); A second water inlet (13) is installed on the upper surface of the left end of the tank body (1), and a left water pipe (10) is provided between the second water inlet (13) and the first water outlet (6); A third water inlet (33) is installed on the upper surface of the right end of the tank body (1), and a right water pipe (7) is provided between the third water inlet (33) and the first water outlet (6); And four groups of filter elements (9) are longitudinally distributed between the lower side of the guide inclined plate (11) and the inner wall of the tank body (1).

2. A coalescing filter tank for treating oily wastewater according to claim 1, characterized in that: The middle pretreatment zone further comprises a first water inlet (3) arranged on the front surface of the tank body (1); the rear end of the first water inlet (3) is in communication with the cyclone (2) and supplies water to the interior of the cyclone (2).

3. A coalescing filter tank for treating oily wastewater according to claim 2, characterized in that: The middle pretreatment zone further comprises a baffle (4) horizontally mounted on the inner wall of the tank body (1) and located at the upper end of the cyclone (2), and a small number of water delivery holes are provided on the upper surface of the baffle (4).

4. A coalescing filter tank for treating oily wastewater according to claim 3, characterized in that: A wastewater cavity is formed between the cyclone (2), the partition (4) and the inner wall of the tank body (1), and a first water outlet (6) communicating with the water cavity is provided at the bottom of the tank body (1).

5. A coalescing filter tank for treating oily wastewater according to claim 4, characterized in that: The surface of the guide inclined plate (11) is provided with a plurality of water holes, and the lower surface of the left end of the tank body (1) is provided with a second water outlet (8) which is in communication with the filter element (9); A third water outlet (34) communicating with the filter element (9) is provided on the lower surface of the right end of the tank body (1).

6. A coalescing filter tank for treating oily wastewater according to claim 5, characterized in that: The left first filtering zone further comprises a water distribution pipe (19) located above the filter bed (12); the water distribution pipe (19) is connected to the second water inlet (13), and a plurality of water distribution ports are evenly arranged on the surface of the water distribution pipe (19).

7. A coalescing filter tank for treating oily wastewater according to claim 6, characterized in that: A flushing structure (17) for cleaning filter material in the filter bed (12) is provided inside the left first filter zone and the right second filter zone. The flushing structure (17) comprises: A scrubbing bucket (21) for cleaning the filter material; A material distribution barrel (22) extending above the filter bed (12), wherein the material distribution barrel (22) is Y-shaped, and a material distribution opening at a lower end thereof extends toward two ends of the filter bed (12); A left electric valve 1 (35) and a right electric valve 2 (36) for controlling the filter material of the scrubbing barrel (21) to enter the cloth barrel (22); And a backwash discharge port (20) installed at the bottom of the tank body (1), wherein the backwash discharge port (20) is located between the two guide inclined plates (11).

8. A coalescing filter tank for treating oily wastewater according to claim 7, characterized in that: The flushing structure (17) further comprises a sewage discharge pipe (14) which is in communication with the interior of the scrubbing bucket (21), and a valve nine (28) is provided on the sewage discharge pipe (14).

9. The coalescing filter tank for treating oily wastewater according to claim 1, characterized in that: The top of the tank body (1) is provided with an oil collecting device which is respectively connected with the left first filter zone, the middle pre-treatment zone and the right second filter zone; the top of the oil collecting device is provided with an oil-water interface meter (16); and oil collecting pipes (15) are provided between the plurality of oil collecting devices.

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