Oily sludge storage, concentration and extraction device and method

Abstract

The invention discloses a device and a method for storing, concentrating and extracting oily sludge. The device comprises a sludge box, a sewage box, a flocculation purification device, a buried intermediate tank, a sludge inlet pipeline and a sludge outlet pipeline, the outlet end of the sludge inlet pipeline extends into the sludge tank, a sludge-water interface instrument is arranged at the top of the sludge tank, a first float-type water decanter is arranged in the sludge tank, a supernatant collecting pipe connected with an outlet of the first float-type water decanter extends into the sewage tank, and a second float-type water decanter is arranged in the sewage tank; an outlet of the second float-type water decanter is connected with a dirty oil recovery system through a floating oil collection pipe; an oil-water interface instrument is arranged at the top of the sewage tank, a sewage conveying pipe connected with the side wall of the lower part of the sewage tank extends into a flocculation purification device, an inverted umbrella-shaped mud cover is arranged in the flocculation purification device, and purified clear liquid is conveyed to an oil removal tank through a purified water collecting pipe; and sewage discharged from the flocculation purification device is discharged into the buried intermediate tank through a sewage collection pipe. And the sludge concentration, storage and extraction process of the existing produced water treatment station is optimized.

Description

Technical Field

[0001] The present invention belongs to the field of oilfield wastewater treatment, and particularly relates to an oil-containing sludge storage, concentration and extraction device and method. Background Art

[0002] During the process of crude oil exploitation, a large amount of produced water is generated. Generally, the produced water is treated and then reinjected into the formation to supplement the formation energy. The produced water contains petroleum, mineral impurities, organic matter, etc., and oil-containing sludge will be generated during the treatment process. Generally, a sludge tank (underground reinforced concrete structure) is set up in the water treatment station to receive the oil-containing sludge and various sewage generated in the station. After the oil-containing sludge in the tank is settled and concentrated, the supernatant enters the sewage tank, and then is lifted into the oil removal tank for treatment. The concentrated sludge is stored in the sludge tank and is regularly cleaned and transported out. The cleaning cycle is often more than 1 year.

[0003] It is found in on-site operation that during the process of concentrating and storing the oil-containing sludge in the tank, it is very easy to cake, and the fluidity becomes poor. Especially for the sludge at the bottom, it is very difficult to pump it out through a water pump during cleaning, and manual cleaning in the tank is often required. The operation of entering the tank belongs to the limited space operation in the oil and gas explosion area, with high safety risks and great operation difficulties. In addition, the quality of the supernatant formed after the concentration of the oil-containing sludge is poor (oil content: 490 - 780 mg / l, suspended solids: 360 - 1300 mg / l), which cannot meet the inlet requirements of the first-stage treatment equipment, the oil removal tank, of the produced water treatment station (requiring both oil content and suspended solids to be ≤ 300 mg / l). Directly entering the oil removal tank will cause the effluent of the oil removal tank to deteriorate, resulting in difficulties in the operation of the entire water treatment system. In addition, the sludge tank and the sewage tank adopt an underground reinforced concrete structure, with a volume ranging from hundreds of cubic meters to thousands of cubic meters, a long construction period, and difficulties in reconstruction and expansion, and cannot well meet the needs of the rolling development of the oilfield. Summary of the Invention

[0004] In view of the above problems, the purpose of the present invention is to provide an oil-containing sludge storage, concentration and extraction device and method to optimize the sludge concentration, storage and extraction processes of existing produced water treatment sites.

[0005] In order to achieve the above invention purpose, the present invention provides the following technical solutions:

[0006] The present invention first discloses an oil-containing sludge storage, concentration and extraction device, including a sludge tank, a sewage tank, a flocculation and purification device, an underground intermediate tank, a sludge inlet pipeline and a sludge outlet pipeline;

[0007] The inlet end of the sludge inlet pipeline is connected to the pressurized sewage discharge pipe of the produced water treatment station. The outlet end of the sludge inlet pipeline extends into the sludge tank from the upper side wall of the sludge tank. A sludge-water interface meter for determining the sludge-water interface and the thickness of the supernatant is installed on the top of the sludge tank. A first floating decanter is arranged inside the sludge tank. An internal circulation fluidization system is also arranged on the sludge tank, and the sludge outlet pipeline is connected to the internal circulation fluidization system;

[0008] The outlet of the first floating decanter is connected to the supernatant collection pipe, and the other end of the supernatant collection pipe extends into the sewage tank from the top of the sewage tank. A second floating decanter is installed in the sewage tank. The outlet of the second floating decanter is connected to the floating oil collection pipe, and the other end of the floating oil collection pipe is connected to the waste oil recovery system. An oil-water interface detector for detecting the oil-water interface and the thickness of the oil layer is installed on the top of the sewage tank. The lower side wall of the sewage tank is connected to the sewage delivery pipe, and the other end of the sewage delivery pipe extends into the flocculation purification device from the lower side wall of the flocculation purification device. An inverted umbrella-shaped mud guard is installed in the flocculation purification device. The upper side wall of the flocculation purification device is connected to a purified water collection pipe for collecting the purified liquid after purification by the inverted umbrella-shaped mud guard, and the other end of the purified water collection pipe is connected to the oil removal tank.

[0009] The buried intermediate tank is buried, and a gravity sewage discharge pipeline and a sewage discharge liquid collection manifold are connected to the side wall of the buried intermediate tank. After the top sewage discharge pipe provided at the top of the flocculation purification device and the top sewage discharge bottom sewage discharge pipe provided at the bottom converge, they are communicated with the sewage discharge liquid collection manifold. The top of the buried intermediate tank is connected to the inlet pipe of the sewage lift pump, and the other end of the inlet pipe of the sewage lift pump is communicated with the inlet end of the sludge inlet pipeline.

[0010] As a preferred solution, the internal circulation fluidization system at least includes a sludge circulation pump, a rotary hydraulic ejector, and a spray pipe, an upper liquid suction pipe, and a lower liquid suction pipe that are sequentially installed on the side wall of the sludge tank from top to bottom. The rotary hydraulic ejector is placed in the sludge tank. The upper liquid suction pipe and the lower liquid suction pipe are respectively connected to the inlet of the sludge circulation pump. The outlet of the sludge circulation pump is divided into two paths. One path is communicated with the sludge outlet pipeline, and the other path is communicated with the spray pipe. The other end of the spray pipe is connected to the inlet of the rotary hydraulic ejector.

[0011] As a further preferred solution of the present invention, the internal circulation fluidization system further includes a backwash pipe. One end of the backwash pipe is communicated with the spray pipe, and the other end of the backwash pipe is communicated with the lower liquid suction pipe.

[0012] As another preferred solution of the present invention, a bypass pipe is connected to the sewage delivery pipe, and the other end of the bypass pipe is connected to the inlet of the sludge circulation pump.

[0013] As a further preferred solution of the present invention, a supernatant collection pump is connected to the supernatant collection pipe, a waste oil collection pump is connected to the floating oil collection pipe, a sewage pressure pump is connected to the sewage delivery pipe, and a sewage lift pump is connected to the inlet pipe of the sewage lift pump.

[0014] Preferably, the top of the sludge tank is connected to a sludge tank vent pipe, the top of the sewage tank is connected to a sewage tank vent pipe, and the top of the buried intermediate tank is connected to a buried intermediate tank vent pipe. After the sludge tank vent pipe, the sewage tank vent pipe and the buried intermediate tank vent pipe are joined, they are connected to the VOC s Treat the exhaust system.

[0015] Preferably, a sludge tank overflow pipe is connected to the side wall of the sludge tank, and a sewage tank overflow pipe is connected to the side wall of the sewage tank. The other ends of the sludge tank overflow pipe and the sewage tank overflow pipe are respectively connected to the sewage liquid collecting pipe.

[0016] A further preferred solution is that the top of the sludge tank is also connected to a first breathing valve, the top of the sewage tank is also connected to a second breathing valve, and the top of the buried intermediate tank is also connected to a third breathing valve and a liquid level detector.

[0017] The present invention further discloses a method for storing, concentrating and extracting oily sludge, comprising the following steps:

[0018] S1, the pressurized sewage liquid of the produced water treatment station is discharged into the sludge box through the sludge discharge pipe, and the gravity sewage liquid of the produced water treatment station is first discharged into the buried intermediate tank, and then lifted by the sewage lifting pump on the sewage lifting pump inlet pipe and merged into the sludge inlet pipeline, and then enters the sludge box;

[0019] S2, a mud-water interface meter is installed on the top of the sludge tank to determine the mud-water interface and the thickness of the supernatant. When the supernatant thickness reaches the set value, the supernatant collection pump is started, and the supernatant is collected and transferred to the sewage tank through the first float-type decanter;

[0020] S3, the oily sludge is stored in the lower part of the sludge tank and is continuously concentrated and compacted. When the sludge storage level is reached, the internal circulation fluidized system is used to clean the sludge tank;

[0021] S4, the sewage tank receives the supernatant transferred from the sludge tank. During the storage of the supernatant in the sewage tank, the floating oil in the water will separate and float up. An oil-water interface meter is installed on the top of the sewage tank to detect the oil-water interface and the thickness of the oil layer. The waste oil collection pump is started according to the thickness of the oil layer, and the floating oil is collected and transferred to the waste oil recovery system through the second float-type decanter in the sewage tank; a sewage booster pump is installed outside the sewage tank to transfer the sewage to the flocculation sedimentation device according to the high and low liquid level signals provided by the oil-water interface meter;

[0022] In S5, a flocculant needs to be added to the inlet of the flocculation purification device. Suspended solids and petroleum substances in the water are mixed with the flocculant and enter the device. Flocs are generated through reaction and then precipitate. After the clear liquid passes through the inverted umbrella-shaped mud guard in the flocculation purification device, it is self-pressurized and transported to the oil removal tank through the purified water collection pipe; the sludge precipitated in the flocculation purification device is regularly discharged into the buried intermediate tank through the bottom sewage discharge pipe; a top sewage discharge pipe is provided at the top of the flocculation purification device to collect the flocs floating with the water flow and regularly discharge them into the buried intermediate tank.

[0023] In S6, the buried intermediate tank collects the gravity sewage discharge liquid, sludge tank overflow liquid, sewage tank overflow liquid and flocculation purification device sewage discharge liquid of the produced water treatment station. A liquid level detector is provided at the top of the buried intermediate tank. According to the high and low liquid levels, the sewage lift pump is started to lift the sewage to the sludge tank.

[0024] As a further preferred solution of the present invention, the method for using the internal circulation fluidization system to clean the sludge tank in step S3 is as follows: The sludge circulation pump first sucks liquid from the upper liquid suction pipe provided on the side wall of the sludge tank, extracts the sludge with a high water content and good fluidity in the upper part of the sludge tank, and then sprays the liquid at a high speed through the rotary hydraulic ejector to impact and stir the sludge accumulated at the bottom, mixing the sludge in the tank evenly until it is completely fluidized. Then the sludge circulation pump changes to suck liquid from the lower liquid suction pipe provided on the side wall of the sludge tank, continuously impacts and stirs the sludge to prevent the sludge from settling and accumulating again. At the same time, the valve on the sludge discharge pipeline is opened to divert and transport part of the sludge until the sludge tank is emptied to the lowest liquid level.

[0025] As a further preferred solution, the method for using the internal circulation fluidization system to clean the sludge tank further includes a bypass process: When there is little sludge or poor fluidity in the upper part of the sludge tank and it cannot meet the requirements of internal circulation fluidization, the sludge circulation pump can suck liquid from the sewage tank through the bypass pipe, pressurize it and then impact and stir the sludge in the sludge tank.

[0026] As another preferred technical solution, the method for using the internal circulation fluidization system to clean the sludge tank in step S3 further includes a backwashing process: The sludge circulation pump can suck liquid from the sewage tank through the bypass pipe or suck liquid from the upper liquid suction pipe, and then backwash the lower liquid suction pipe through the backwash pipe to dredge the pipeline.

[0027] Due to the adoption of the above technical solutions, the present invention has the following beneficial effects:

[0028] In the present invention, underground sludge ponds and sewage ponds are changed into above-ground box structures, which can be flexibly combined and expanded according to the scale of the station yard, facilitating reconstruction, expansion and relocation. The sludge box process is optimized to realize the extraction of concentrated sludge by a water pump. A sludge circulation pump and a rotary hydraulic ejector are equipped in the sludge box. Before cleaning, an internal circulation fluidization process is carried out. The sludge with high water content and good fluidity in the upper part of the sludge box is extracted, pressurized by the sludge circulation pump, and then ejected at high speed by the rotary hydraulic ejector to impact and stir the sludge at the bottom of the box, mixing the sludge in the box evenly and completely fluidizing it. Then, while carrying out internal circulation, the sludge is extracted and sent to the sludge treatment device. The supernatant treatment process is increased. The supernatant is degreased and flocculated and settled and then enters the oil removal tank to reduce the impact on the water treatment process.

[0029] The above description is only an overview of the technical solution of the present invention. In order to understand the technical means of the present invention more clearly and implement it according to the content of the description, the following takes the preferred embodiments of the present invention and describes them in detail in conjunction with the drawings as follows. Brief Description of the Drawings

[0030] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the drawings required to be used in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other design solutions and drawings can also be obtained based on these drawings.

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

[0032] Description of the Reference Numerals in the Drawings:

[0033] 1. Sludge box; 2. Sewage box; 3. Flocculation purification device; 4. Buried intermediate tank; 5. Sludge circulation pump; 6. Supernatant collection pump; 7. Waste oil collection pump; 8. Sewage pressurization pump; 9. Sewage lift pump; 10. First floating decanter; 11. Rotary hydraulic ejector; 12. Mud inlet pipeline; 13. Injection pipe; 14. Upper liquid suction pipe; 15. Lower liquid suction pipe; 16. Backwashing pipe; 17. Mud outlet pipeline; 18. Sludge box overflow pipe; 19. Sludge box vent pipe; 20. Sewage box overflow pipe; 21. Sewage box drain pipe; 22. Sewage box vent pipe; 23. Top sewage discharge pipe; 24. Bottom sewage discharge pipe; 25. Sewage discharge liquid collection manifold; 26. Buried intermediate tank vent pipe; 27. Sewage lift pump inlet pipe; 28. Mud-water interface meter; 29. First breathing valve; 30. Inverted umbrella-shaped mud guard; 31. Bypass pipe; 32. Liquid level detector; 33. Purified water collection pipe; 34. Second floating decanter; 35. Oil-water interface meter; 36. Second breathing valve; 37. Third breathing valve; 38. Gravity sewage discharge pipeline.

[0034] To make the above objects, features, and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. Specific Embodiments

[0035] The content of the present invention can be further understood by referring to the following detailed description of the preferred embodiments of the present invention and the included examples. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the art to which the present invention belongs. If the definitions of specific terms disclosed in the prior art are inconsistent with any definitions provided in the present invention, the definitions provided in the present invention shall prevail.

[0036] It should be noted that in the embodiments of the present invention, if there are descriptions involving "first", "second", etc., such descriptions of "first", "second", etc. are only for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the quantity of the indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include at least one of such features. In addition, the technical solutions between various embodiments can be combined with each other, but it must be based on the ability of those of ordinary skill in the art to implement. When the combination of technical solutions results in contradictions or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0037] In a typical embodiment of the present application, an oily sludge storage, concentration, and extraction device is provided. Referring to Figure 1 , it includes a sludge tank 1, a sewage tank 2, a flocculation purification device 3, an underground intermediate tank 4, a sludge inlet pipeline 12, and a sludge outlet pipeline 17;

[0038] The inlet end of the sludge inlet pipeline 12 is connected to the pressurized sewage discharge pipe of the produced water treatment station. The outlet end of the sludge inlet pipeline 12 extends into the sludge tank 1 from the upper side wall of the sludge tank 1. A sludge-water interface meter 28 for determining the sludge-water interface and the thickness of the supernatant is installed on the top of the sludge tank 1. A first floating decanter 10 is arranged inside the sludge tank 1. An internal circulation fluidization system is also arranged on the sludge tank 1. The sludge outlet pipeline 17 is connected to the internal circulation fluidization system; the outlet of the first floating decanter 10 is connected to the supernatant collection pipe, and the other end of the supernatant collection pipe extends into the sewage tank 2 from the top of the sewage tank 2. A second floating decanter 34 is arranged inside the sewage tank 2. The outlet of the second floating decanter 34 is connected to the floating oil collection pipe, and the other end of the floating oil collection pipe is connected to the waste oil recovery system; an oil-water interface meter 35 for detecting the oil-water interface and the thickness of the oil layer is installed on the top of the sewage tank 2. The lower side wall of the sewage tank 2 is connected to a sewage delivery pipe, and the other end of the sewage delivery pipe extends into the flocculation purification device 3 from the lower side wall of the flocculation purification device 3. An inverted umbrella-shaped mud baffle 30 is installed inside the flocculation purification device 3. A purified water collection pipe 33 for collecting the purified supernatant after the purification of the inverted umbrella-shaped mud baffle 30 is connected to the upper side wall of the flocculation purification device 3. The other end of the purified water collection pipe 33 is connected to an oil removal tank; the pressurized sewage discharge liquid of the produced water treatment station is discharged into the sludge tank 1 through the sludge discharge pipe, and oil-containing sludge and supernatant are formed through static sedimentation and separation. The sludge is stored in the sludge tank 1, and is regularly pumped to the sludge treatment facility, while the supernatant enters the sewage tank 2 for storage; the floating oil generated during the storage of the supernatant is collected and transported to the waste oil recovery system, and the remaining sewage is lifted by a sewage booster pump 8 on the sewage delivery pipe and enters the flocculation purification device 3 for water quality purification, and the purified water enters the oil removal tank.

[0039] The gravity sewage discharge liquid of the produced water treatment station is discharged into the underground intermediate tank 4. The underground intermediate tank 4 is buried underground, and a gravity sewage discharge pipeline 38 and a sewage discharge liquid collection manifold 25 are connected to the side wall of the underground intermediate tank 4. After the top sewage discharge pipe 23 and the bottom sewage discharge pipe 24 arranged at the top and bottom of the flocculation purification device 3 converge, they are communicated with the sewage discharge liquid collection manifold 25; the top of the underground intermediate tank 4 is connected to a sewage lift pump inlet pipe 27, and the other end of the sewage lift pump inlet pipe 27 is communicated with the inlet end of the sludge inlet pipeline 12.

[0040] Preferably, the sludge tank 1 adopts a ground box structure, a square sealed box body, and is constructed by factory prefabrication and on-site assembly, and multiple box bodies can be combined for use. The sewage discharge of the produced water treatment station is significantly intermittent. During the period between two sewage discharges, the previous sewage discharge can be statically settled in the sludge tank 1 to achieve sludge concentration and stratification. The upper part of the tank is the supernatant, and the lower part is the oil-containing sludge.

[0041] In a further preferred embodiment, the internal circulation fluidization system at least includes a sludge circulation pump 5, a rotary hydraulic ejector 11, and an ejection pipe 13, an upper suction pipe 14, and a lower suction pipe 15 installed on the side wall of the sludge box 1 from top to bottom, wherein the rotary hydraulic ejector 11 is placed in the sludge box 1; the upper suction pipe 14 and the lower suction pipe 15 are respectively connected to the inlet of the sludge circulation pump 5, and the outlet of the sludge circulation pump 5 is respectively two-way, one is connected to the mud outlet pipeline 17, and the other is connected to the ejection pipe 13, and the other end of the ejection pipe 13 is connected to the inlet of the rotary hydraulic ejector 11. The sewage generated by the water treatment station is divided into two types according to the discharge pressure, one with pressure and the other without pressure (i.e., gravity sewage discharge). The pressurized sewage liquid is directly discharged into the sludge box 1, and the gravity sewage liquid is discharged into the buried intermediate tank 4 and lifted into the sludge box 1 by the sewage lifting pump 9. Various types of sewage are statically settled and stratified in the sludge tank 1, with oily sludge at the bottom and supernatant at the top. The supernatant is collected by the first float decanter 10 and transferred to the sewage tank 2 through the supernatant collection pipe; the bottom sludge is stored at the bottom of the tank and continuously concentrated and compacted. When the sludge storage level is reached, cleaning operations are carried out. When cleaning the sludge, the sludge internal circulation fluidization process is first carried out: the sludge circulation pump 5 (also serving as a sludge extraction pump) first sucks liquid from the upper suction pipe 14 arranged on the side wall of the sludge box 1, extracts the sludge with high water content and good fluidity in the upper part of the sludge box 1, and then uses the rotary hydraulic ejector 11 to spray the liquid at high speed, impact and stir the sludge accumulated at the bottom, and mix the sludge in the box evenly until the sludge is completely fluidized. Then the sludge circulation pump sucks liquid from the lower suction pipe 15 arranged on the side wall of the sludge box 1, and continuously impacts and stirs the sludge to prevent the sludge from settling and accumulating again. At the same time, the sludge circulation pump 5 mud valve is opened to extract part of the sludge through the mud outlet pipeline 17 for external transmission until the sludge box 1 is emptied to the lowest liquid level.

[0042] In a further preferred embodiment, the internal circulation fluidized system further comprises a backwash pipe 16, one end of which is connected to the injection pipe 13, and the other end of which is connected to the lower suction pipe 15. Therefore, the sludge circulation pump 5 can suck liquid from the upper part of the sewage tank 2 or the sludge tank 1 to flush the lower suction pipe 15 to prevent the pipeline from being blocked.

[0043] In order to improve reliability, a bypass process is provided: that is, a bypass pipe 31 is connected to the sewage delivery pipe, and the other end of the bypass pipe 31 is connected to the inlet of the sludge circulation pump 5. The sludge circulation pump 5 can absorb water from the sewage tank 2, and impact and stir the sludge in the sludge tank 1 after pressurization.

[0044] In another preferred embodiment, a supernatant collection pump 6 is connected to the supernatant collection pipe, a dirty oil collection pump 7 is connected to the floating oil collection pipe, a sewage booster pump 8 is connected to the sewage delivery pipe, and a sewage booster pump 9 is connected to the sewage booster pump inlet pipe 27. The sewage tank 2 receives the supernatant transferred from the sludge tank 1, adjusts and stores the water quality, and collects the floating oil. The sewage tank is provided with a second float-type decanter 34, the outlet of the second float-type decanter 34 is connected to the floating oil collection pipe, and a dirty oil collection pump is installed on the floating oil collection pipe to collect the floating oil separated during the storage of the supernatant and transfer it to the dirty oil recovery system. A sewage booster pump 8 is provided outside the sewage tank 2 to pressurize the sewage in the sewage tank 2 and transfer it to the flocculation sedimentation device 3. The flocculation purification device 3 is a cylindrical closed pressure equipment, and a flocculant needs to be added at the inlet. Its function is to react the suspended matter and petroleum in the water with the flocculant to produce flocs and precipitate, thereby purifying the water quality. The purified water enters the oil removal tank by self-pressure, and the precipitated sludge is regularly discharged into the buried middle 4 and transferred to the sludge tank 1 by the sewage lifting pump 9.

[0045] As a preferred embodiment, the top of the sludge tank 1 is connected to a sludge tank vent pipe 19, the top of the sewage tank 2 is connected to a sewage tank vent pipe 22, and the top of the buried intermediate tank 4 is connected to a buried intermediate tank vent pipe 26. After the sludge tank vent pipe 19, the sewage tank vent pipe 22 and the buried intermediate tank vent pipe 26 are joined, they are connected to the VOC s Treat the exhaust system.

[0046] In a specific preferred embodiment, a sludge tank overflow pipe 18 is also connected to the side wall of the sludge tank 1, and a sewage tank overflow pipe 20 is also connected to the side wall of the sewage tank 2. The other ends of the sludge tank overflow pipe 18 and the sewage tank overflow pipe 20 are respectively connected to the sewage liquid collection pipe manifold 25.

[0047] Preferably, the top of the sludge tank 1 is also connected to a first breathing valve 29 , the top of the sewage tank 2 is also connected to a second breathing valve 36 , and the top of the buried intermediate tank 4 is also connected to a third breathing valve 37 and a liquid level detector 32 .

[0048] Preferably, a drain line is also connected to the side wall of the sewage tank 2, the other end of the drain line is connected to the sewage tank overflow pipe 20, and a sewage tank drain pipe 21 is installed on the drain line.

[0049] In another typical embodiment of the present application, a method for storing, concentrating and extracting oily sludge is disclosed, comprising the following steps:

[0050] S1, the pressurized sewage liquid of the produced water treatment station is discharged into the sludge tank 1 through the sludge discharge pipe 12, and the gravity sewage liquid of the produced water treatment station is first discharged into the buried intermediate tank 4, and then lifted by the sewage lifting pump 9 on the sewage lifting pump inlet pipe 27 and merged into the sludge inlet pipeline 12, and then enters the sludge tank 1;

[0051] S2. A sludge-water interface detector 28 is installed on the top of the sludge tank 1 to determine the sludge-water interface and the thickness of the supernatant. When the thickness of the supernatant reaches the set value, the supernatant collection pump 6 is started, and the supernatant is collected and transferred to the sewage tank 2 through the first floating decanter 10.

[0052] S3. The oily sludge is stored in the lower part of the sludge tank 1 and continuously concentrated and compacted. When the sludge storage liquid level is reached, an internal circulation fluidization system is used to clean the sludge tank 1.

[0053] S4. The sewage tank 2 receives the supernatant transferred from the sludge tank 1. During the storage of the supernatant in the sewage tank 2, the floating oil in the water will separate and float upward. An oil-water interface detector 35 is installed on the top of the sewage tank 2 to detect the oil-water interface and the thickness of the oil layer. According to the thickness of the oil layer, the waste oil collection pump 7 is started, and the floating oil is collected and transferred to the waste oil recovery system through the second floating decanter 34 in the sewage tank 2. A sewage booster pump 8 is provided outside the sewage tank 2, and the sewage is transported to the flocculation and precipitation device 3 according to the high and low liquid level signals provided by the oil-water interface detector 35.

[0054] S5. A flocculant needs to be added to the inlet of the flocculation and purification device 3. The suspended solids and petroleum substances in the water are mixed with the flocculant and enter the device, where they react to form flocs and precipitate. After the clear liquid passes through the inverted umbrella-shaped mud guard 30 in the flocculation and purification device 3, it is self-pressurized and transported to the oil removal tank through the purified water collection pipe 33. The sludge precipitated in the flocculation and purification device 3 is regularly discharged into the underground intermediate tank 4 through the bottom sewage discharge pipe 24. A top sewage discharge pipe 23 is provided at the top of the flocculation and purification device 3 to collect the flocs floating with the water flow and regularly discharge them into the underground intermediate tank 4.

[0055] S6. The underground intermediate tank 4 collects the gravity sewage discharge liquid, the overflow liquid of the sludge tank 1, the overflow liquid of the sewage tank 2, and the sewage discharge liquid of the flocculation and purification device 3. A liquid level detector 32 is provided at the top of the underground intermediate tank 4. According to the high and low liquid levels, the sewage lift pump 9 is started to lift the sewage into the sludge tank 1.

[0056] In a further preferred embodiment, the method of using the internal circulation fluidization system to clean the sludge tank 1 in step S3 is as follows: The sludge circulation pump 5 first sucks liquid from the upper liquid suction pipe 14 provided on the side wall of the sludge tank 1, extracts the sludge with a high water content and good fluidity in the upper part of the sludge tank 1, and then sprays the liquid at a high speed through the rotary hydraulic ejector 11 to impact and stir the sludge accumulated at the bottom, mixing the sludge in the tank evenly until it is completely fluidized. Then the sludge circulation pump 5 changes to suck liquid from the lower liquid suction pipe 15 provided on the side wall of the sludge tank 1, continuously impacts and stirs the sludge to prevent the sludge from settling and accumulating again. At the same time, the valve on the sludge discharge pipeline 17 is opened to divert and transport part of the sludge until the sludge tank 1 is emptied to the lowest liquid level.

[0057] In a further preferred embodiment, the method of cleaning the sludge tank 1 using an internal circulation fluidization system also includes a bypass process: when the sludge in the upper part of the sludge tank 1 is less or has poor fluidity and cannot meet the internal circulation fluidization requirements, the sludge circulation pump 5 can absorb liquid from the sewage tank 2 through the bypass pipe 31, and after pressurization, impact and stir the sludge in the sludge tank 1.

[0058] In another preferred embodiment, the method of using an internal circulation fluidized system to clean the sludge tank 1 in step S3 also includes a backwashing process: the sludge circulation pump 5 can absorb liquid from the sewage tank 2 through the bypass pipe 31 or absorb liquid through the upper suction pipe 14, and then backwash the lower suction pipe 15 through the backwash pipe 16 to clear the pipeline.

[0059] The present invention will be further described below in conjunction with specific embodiments:

[0060] Example 1

[0061] This embodiment relates to a method for storing, concentrating and extracting oily sludge, comprising:

[0062] (1) The pressurized sewage liquid of the produced water treatment station is discharged into the sludge tank 1 through the sludge discharge pipe 12; the gravity sewage liquid of the produced water treatment station is first discharged into the buried intermediate tank 4, and then lifted by the sewage lifting pump 9 and collected into the sludge inlet pipe 12 and enters the sludge tank 1.

[0063] The sludge box 1 adopts an above-ground box structure, a square closed box, and is prefabricated in the factory and assembled on site. Multiple boxes can be used in combination. The sewage discharge of the produced water treatment station is obviously intermittent. During the two sewage discharges, the previous sewage can be statically settled in the sludge box 1 to achieve sludge concentration and stratification. The upper part of the box is the supernatant, and the lower part is the oily sludge.

[0064] (2) Before the next sewage discharge, the formed supernatant needs to be collected. Specifically, a mud-water interface meter 28 is installed on the top of the sludge tank 1 to determine the mud-water interface and the thickness of the supernatant. When the supernatant thickness reaches the set value, the supernatant collection pump 6 is started, and the supernatant is collected and transferred to the sewage tank 2 through the first float-type decanter 10.

[0065] (3) The oily sludge is stored in the lower part of the sludge tank 1 and is continuously concentrated and compacted. When the sludge storage level is reached, the sludge tank 1 needs to be cleaned. The designed storage capacity of the sludge in the sludge tank 1 should be determined according to the sludge cleaning cycle, which is generally about 1 year.

[0066] When cleaning the sludge tank 1, the sludge at the bottom of the tank has a high degree of concentration, is severely caked and has poor fluidity, while the sludge at the upper part has a high water content and better fluidity. To facilitate the pumping by the water pump, it is necessary to first carry out the sludge internal circulation fluidization operation: The sludge circulation pump 5 first sucks liquid from the upper liquid suction pipe 14 provided on the side wall of the sludge tank, extracting the sludge with a high water content and better fluidity at the upper part of the sludge tank 1. Then, through the rotary hydraulic ejector 11, the liquid is ejected at a high speed in a rotating manner to impact and stir the sludge accumulated at the bottom, mixing the sludge in the tank evenly until it is completely fluidized. Then, the sludge circulation pump 2 changes to suck liquid from the lower liquid suction pipe 15 provided on the side wall of the sludge tank, continuously impacting and stirring the sludge to prevent the sludge from settling and accumulating again. At the same time, the valve on the sludge discharge pipeline 17 is opened to divert and transport some of the sludge out until the sludge tank 1 is emptied to the lowest liquid level.

[0067] (4). To improve the reliability of the process, a bypass process is provided: When there is little sludge or poor fluidity in the upper part of the sludge tank 1 and it cannot meet the requirements of internal circulation fluidization, the sludge circulation pump 5 can suck liquid from the sewage tank 2 through the bypass pipe 31, and after pressurization, impact and stir the sludge in the sludge tank 1; At the same time, a backwashing process is provided: Since the lower liquid suction pipe 15 is laid at the bottom of the sludge tank and the sludge has a high degree of concentration, there is a possibility of being blocked by the sludge. The sludge circulation pump 5 can suck liquid from the sewage tank 2 through the bypass pipe 31 or suck liquid from the upper liquid suction pipe 14, and open the valve of the backwash pipe 16 to carry out backwashing on the lower liquid suction pipe 15 to dredge the pipeline.

[0068] (5). The sewage tank 2 receives the supernatant transferred from the sludge tank 1, and its main functions are to store and adjust the water quality evenly and collect floating oil.

[0069] The sewage tank 2 adopts a ground box structure, a square closed box body, and is constructed by prefabrication in the factory and on-site assembly. Multiple box bodies can be used in combination. During the storage process of the supernatant in the sewage tank 2, the floating oil in the water will separate and float upward. An oil-water interface detector 28 is installed on the top of the sewage tank, which can detect the oil-water interface and the thickness of the oil layer. According to the thickness of the oil layer, the waste oil collection pump 7 is started, and the floating oil is collected and transferred to the waste oil recovery system through the second floating bucket type water decanter 34. A sewage booster pump 8 is provided outside the sewage tank 2, and the sewage is transported to the flocculation and precipitation device 3 according to the high liquid level and low liquid level (sludge storage liquid level) signals provided by the oil-water interface detector 28.

[0070] (6). The flocculation and purification device 3 is a cylindrical closed pressure-bearing equipment, and a flocculant needs to be added at the inlet. The suspended solids and petroleum substances in the water are mixed with the flocculant and enter the device, reacting to produce flocs and precipitate. The purified clear liquid is self-pressurized and transported to the oil removal tank through the inverted umbrella-shaped mud guard 30 and the purified water collection pipe 33 of the clear liquid. The sludge precipitated in the device is regularly discharged into the buried intermediate tank 4 through the bottom sewage discharge pipe 24. A top sewage discharge pipe 23 is provided at the top of the flocculation and purification device 3 to collect the flocs floating with the water flow and regularly discharge them into the buried intermediate tank 4.

[0071] (7) The underground intermediate tank 4 is an underground airtight tank, mainly used to collect the gravity sewage discharge liquid, sludge tank overflow liquid, sewage tank overflow liquid and flocculation purification device 3 sewage discharge liquid of the produced water treatment station. A liquid level detector 32 is provided at the top of the underground intermediate tank 4. According to the high and low liquid levels, the sewage lift pump 9 is started to lift the sewage to the sludge tank 1.

[0072] (8) Breather valves and vent pipes are provided at the tops of the sludge tank 1, the sewage tank 2 and the underground intermediate tank 4. The vent pipes converge and are connected to the in-station VOC s treatment extraction system. To avoid VOC s volatilization, the VOC s treatment extraction system maintains the gas phase space in the tank at a slightly negative pressure state, and the negative pressure value is slightly higher than the negative pressure opening value set by the breather valve.

[0073] The above are only the preferred embodiments of the present invention, which are illustrative for the present invention rather than limiting the scope of the present invention. Without departing from the design spirit of the present invention, various deformations and improvements made by those of ordinary skill in the art to the technical solution of the present invention shall fall within the protection scope determined by the claims of the present invention.

Claims

1. An oil-containing sludge storage, concentration and extraction device, characterized in that: it includes a sludge tank (1), a sewage tank (2), a flocculation and purification device (3), an underground intermediate tank (4), a sludge inlet pipeline (12) and a sludge outlet pipeline (17); The inlet end of the sludge inlet pipeline (12) is connected to the pressurized sewage discharge pipe of the produced water treatment station. The outlet end of the sludge inlet pipeline (12) extends into the sludge tank (1) from the upper side wall of the sludge tank (1). A sludge-water interface meter (28) for determining the sludge-water interface and the thickness of the supernatant is installed on the top of the sludge tank (1). A first floating decanter (10) is arranged inside the sludge tank (1). An internal circulation fluidization system is also arranged on the sludge tank (1). The sludge outlet pipeline (17) is connected to the internal circulation fluidization system; The outlet of the first floating decanter (10) is connected to a supernatant collection pipe. The other end of the supernatant collection pipe extends into the sewage tank (2) from the top of the sewage tank (2). A second floating decanter (34) is arranged inside the sewage tank (2). The outlet of the second floating decanter (34) is connected to an oil slick collection pipe. The other end of the oil slick collection pipe is connected to an oily sewage recovery system. An oil-water interface meter (35) for detecting the oil-water interface and the thickness of the oil layer is installed on the top of the sewage tank (2). The lower side wall of the sewage tank (2) is connected to a sewage delivery pipe. The other end of the sewage delivery pipe extends into the flocculation and purification device (3) from the lower side wall of the flocculation and purification device (3). An inverted umbrella-shaped mud baffle (30) is installed inside the flocculation and purification device (3). A purified water collection pipe (33) for collecting the purified liquid after purification by the inverted umbrella-shaped mud baffle (30) is connected to the upper side wall of the flocculation and purification device (3). The other end of the purified water collection pipe (33) is connected to an oil removal tank; The underground intermediate tank (4) is buried underground, and a gravity sewage discharge pipeline (38) and a sewage discharge liquid collection manifold (25) are connected to the side wall of the underground intermediate tank (4). After the top sewage discharge pipe (23) and the bottom sewage discharge pipe (24) arranged at the bottom of the flocculation and purification device (3) converge, they are communicated with the sewage discharge liquid collection manifold (25). The top of the underground intermediate tank (4) is connected to a sewage lift pump inlet pipe (27). The other end of the sewage lift pump inlet pipe (27) is communicated with the inlet end of the sludge inlet pipeline (12).

2. The oil-containing sludge storage, concentration and extraction device according to claim 1, characterized in that: The internal circulation fluidization system at least includes a sludge circulation pump (5), a rotary hydraulic ejector (11), and a spray pipe (13), an upper liquid suction pipe (14) and a lower liquid suction pipe (15) which are sequentially installed on the side wall of the sludge tank (1) from top to bottom. The rotary hydraulic ejector (11) is placed inside the sludge tank (1). The upper liquid suction pipe (14) and the lower liquid suction pipe (15) are respectively connected to the inlet of the sludge circulation pump (5). The outlet of the sludge circulation pump (5) has two paths. One path is communicated with the sludge outlet pipeline (17), and the other path is communicated with the spray pipe (13). The other end of the spray pipe (13) is connected to the inlet of the rotary hydraulic ejector (11).

3. The oil-containing sludge storage, concentration and extraction device according to claim 2, It is characterized in that: The inner circulation fluidization system further includes a backwash pipe (16), one end of the backwash pipe (16) is communicated with the injection pipe (13), and the other end of the backwash pipe (16) is communicated with the lower liquid suction pipe (15).

4. The oily sludge storage, concentration and extraction device according to claim 2, It is characterized in that: A bypass pipe (31) is connected to the sewage delivery pipe, and the other end of the bypass pipe (31) is connected to the inlet of the sludge circulation pump (5).

5. The oily sludge storage, concentration and extraction device according to claim 1, It is characterized in that: An supernatant collection pump (6) is connected to the supernatant collection pipe, an oily sewage collection pump (7) is connected to the floating oil collection pipe, a sewage pressurizing pump (8) is connected to the sewage delivery pipe, and a sewage lift pump (9) is connected to the sewage lift pump inlet pipe (27).

6. The oily sludge storage, concentration and extraction device according to claim 1, It is characterized in that: The top of the sludge tank (1) is connected with a sludge tank vent pipe (19), the top of the sewage tank (2) is connected with a sewage tank vent pipe (22), the top of the underground intermediate tank (4) is connected with an underground intermediate tank vent pipe (26). After the sludge tank vent pipe (19), the sewage tank vent pipe (22) and the underground intermediate tank vent pipe (26) converge, they are connected to the in-station VOC s treatment air extraction system.

7. The oily sludge storage, concentration and extraction device according to claim 1, It is characterized in that: A sludge tank overflow pipe (18) is further connected to the side wall of the sludge tank (1), a sewage tank overflow pipe (20) is further connected to the side wall of the sewage tank (2), and the other ends of the sludge tank overflow pipe (18) and the sewage tank overflow pipe (20) are respectively communicated with the sewage discharge liquid collection pipe manifold (25).

8. The oily sludge storage, concentration and extraction device according to claim 1, It is characterized in that: A first breathing valve (29) is further connected to the top of the sludge tank (1), a second breathing valve (36) is further connected to the top of the sewage tank (2), and a third breathing valve (37) and a liquid level detector (32) are further connected to the top of the underground intermediate tank (4).

9. An oily sludge storage, concentration and extraction method, It is characterized in that, including the following steps: S1, The pressurized sewage discharge liquid of the produced water treatment station is discharged into the sludge tank (1) through the sludge discharge pipe (12), and the gravity sewage discharge liquid of the produced water treatment station is first discharged into the underground intermediate tank (4), and then lifted by the sewage lift pump (9) on the sewage lift pump inlet pipe (27) and then converges into the inlet sludge pipeline (12), and then enters the sludge tank (1); S2, A sludge-water interface instrument (28) is installed on the top of the sludge tank (1) to determine the sludge-water interface and the thickness of the supernatant. When the thickness of the supernatant reaches the set value, the supernatant collection pump (6) is started, and the supernatant is collected and transferred to the sewage tank (2) through the first floating decanter (10); S3, The oily sludge is stored in the lower part of the sludge tank (1), continuously concentrated and compacted. When the sludge storage liquid level is reached, the inner circulation fluidization system is used to clean the sludge tank (1); S4. The sewage tank (2) receives the supernatant transferred from the sludge tank (1). During the storage process of the supernatant in the sewage tank (2), the floating oil in the water will separate and float upward. An oil-water interface detector (35) is installed at the top of the sewage tank (2) to detect the oil-water interface and the thickness of the oil layer. According to the thickness of the oil layer, the waste oil collection pump (7) is started, and the floating oil is collected and transferred to the waste oil recovery system through the second floating decanter (34) in the sewage tank (2); A sewage booster pump (8) is provided outside the sewage tank (2), and the sewage is transported to the flocculation and sedimentation device (3) according to the high and low liquid level signals provided by the oil-water interface detector (35). S5. Flocculant needs to be added at the inlet of the flocculation and purification device (3). The suspended solids and petroleum substances in the water are mixed with the flocculant and enter the device, react to form flocs, and precipitate. After the clear liquid passes through the inverted umbrella-shaped mud guard (30) in the flocculation and purification device (3), it is self-pressurized and transported to the oil removal tank through the purified water collection pipe (33); The sludge precipitated in the flocculation and purification device (3) is regularly discharged into the buried intermediate tank (4) through the bottom sewage discharge pipe (24); A top sewage discharge pipe (23) is provided at the top of the flocculation and purification device (3) to collect the flocs floating with the water flow and discharge them into the buried intermediate tank (4) regularly. S6. The buried intermediate tank (4) collects the gravity sewage discharge liquid, the overflow liquid of the sludge tank (1), the overflow liquid of the sewage tank (2), and the sewage discharge liquid of the flocculation and purification device (3). A liquid level detector (32) is provided at the top of the buried intermediate tank (4), and the sewage lift pump (9) is started according to the high and low liquid levels to lift the sewage into the sludge tank (1).

10. The method for storing, concentrating and extracting oily sludge as claimed in claim 9, characterized in that, The method for cleaning the sludge tank (1) by using the internal circulation fluidization system in step S3 is as follows: The sludge circulation pump (5) first sucks liquid from the upper liquid suction pipe (14) provided on the side wall of the sludge tank (1), extracts the sludge with high water content and good fluidity in the upper part of the sludge tank (1), and then sprays the liquid at high speed through the rotary hydraulic ejector (11) to impact and stir the sludge accumulated at the bottom, mix the sludge in the tank evenly until it is completely fluidized. Then the sludge circulation pump (5) changes to suck liquid from the lower liquid suction pipe (15) provided on the side wall of the sludge tank (1), continuously impacts and stirs the sludge to prevent the sludge from settling and accumulating again. At the same time, the valve on the sludge discharge pipeline (17) is opened to divert and transport part of the sludge until the sludge tank (1) is emptied to the lowest liquid level.

11. The method for storing, concentrating and extracting oily sludge as claimed in claim 10, characterized in that, The method for cleaning the sludge tank (1) by using the internal circulation fluidization system in step S3 further includes a bypass process: When there is little sludge or poor fluidity in the upper part of the sludge tank (1) and it cannot meet the requirements of internal circulation fluidization, the sludge circulation pump (5) can suck liquid from the sewage tank (2) through the bypass pipe (31), and after pressurization, impact and stir the sludge in the sludge tank (1).

12. The method for storing, concentrating and extracting oily sludge as claimed in claim 10, characterized in that, The method for cleaning the sludge tank (1) by using the internal circulation fluidization system in the step S3 further includes a backwashing process: after the sludge circulation pump (5) sucks liquid from the sewage tank (2) through the bypass pipe (31) or sucks liquid through the upper liquid suction pipe (14), it then performs backwashing on the lower liquid suction pipe (15) through the backwash pipe (16) to dredge the pipeline.

Images