A fully enclosed oil tank dehydration system

Abstract

The present invention belongs to the field of petrochemical technology, and specifically discloses a fully enclosed oil tank dehydration system, including an oil storage tank and a dehydrator, and also includes a sand settling tank, which is installed between the oil storage tank and the dehydrator through a connecting pipe; a buffer tank: the buffer tank is provided with a suspension piston that can be suspended on the liquid surface, and the piston divides the buffer tank into an upper adjustment area and a lower liquid storage area; and a sewage discharge device. The oil tank dehydration system completes the sediment sedimentation treatment process, the preliminary dehydration process of oil-water separation, the further interception of oil sludge and the air pressure treatment process in the adjustment pipeline completely in a closed pipeline, and then completes the final dehydration, effectively ensuring that the dehydration pipeline is not blocked, ensuring the smooth flow of the pipeline, and also making the final dewatered sewage free of oil, greatly improving the utilization rate of oil, and during dehydration, no toxic and harmful gases will be discharged into the air, and no pollution will be caused to the environment and soil, and it is safe and reliable to use.

Description

Technical Field

[0001] The invention belongs to the technical field of petrochemical industry, and particularly relates to a fully enclosed oil tank dehydration system. Background Art

[0002] In the prior art, there is some water in the oil stored in the oil storage tanks commonly used in the petrochemical industry. After long-term storage, the water will settle to the bottom of the oil storage tank. When in use, in order to ensure the purity of the oil, the water at the bottom of the tank must be dehydrated. The current dehydration technology is to discharge the water directly into the sewage pool under the storage tank, and then flow into the sewer for discharge. With the continuous improvement of safety and environmental protection requirements, this direct exposure dehydration method has many disadvantages, as follows:

[0003] 1. When the oil tank is dehydrated, the sewage is discharged into the sewage pool without any treatment. A large amount of VOCs, H2S and other toxic and harmful gases in the oil-water mixture in the oil tank evaporate into the air. Since the density of these toxic gases is greater than that of air, they float on the ground or penetrate into the soil after a long period of sedimentation, causing air pollution and soil pollution, which poses a great safety hazard and threatens the health and life safety of on-site workers.

[0004] 2. Since the dehydrated wastewater is transported through underground pipelines buried underground, if the underground pipelines are damaged or leaking and cannot be discovered in time, the soil and groundwater will be polluted, violating the provisions of the Soil Pollution Prevention and Control Law of the People's Republic of China (promulgated on August 31, 2018 and implemented on January 1, 2019), and failing to better protect and improve the ecological environment and prevent soil pollution, and failing to protect public health;

[0005] 3. Oil leakage accidents often occur during the dehydration process. The leaked oil is viscous and easy to form blockages. If it cannot be discharged from the sewer in time, it will overflow to the ground, polluting the air, surface water and soil, and posing a huge safety hazard. At the same time, the oil cannot be collected to a large extent, which also causes a certain degree of waste.

[0006] Therefore, it is urgent to develop an oil tank dehydration system that will not pollute the environment and soil, will not easily clog the pipeline, and will not emit toxic gases into the air in a completely enclosed space during dehydration. Summary of the invention

[0007] The purpose of the present invention is to overcome the deficiencies of the prior art and disclose a fully enclosed oil tank dehydration system, which completes the sedimentation treatment process, the preliminary dehydration process of oil-water separation, and the final dehydration by further interception of the oil sludge completely in a closed pipeline, effectively ensuring that the entire dehydration pipeline is not blocked, ensuring the smooth flow of the pipeline, and also making the sewage finally dehydrated without oil, greatly reducing the oil loss rate, and no toxic and harmful gases are discharged into the air during dehydration, and no pollution is caused to the environment and soil, and the use is safe and reliable.

[0008] In order to achieve the above technical objectives, the present invention is implemented according to the following technical solutions:

[0009] A fully enclosed oil tank dehydration system according to the present invention comprises an oil storage tank and a dehydrator, and further comprises a sand settling tank: the sand settling tank is installed between the bottom drain port of the oil storage tank and the water inlet end of the dehydrator through a connecting pipe, and the sand settling tank comprises a top inlet connected to the bottom drain port of the oil storage tank, a top outlet connected to the top of the dehydrator, and further comprises a bottom outlet for outputting silt;

[0010] Buffer tank: connected to the water outlet end of the dehydrator through a connecting pipe, on which a dehydration valve, a one-way valve and an oil-water detection sensor are arranged in sequence. A suspension piston that can be suspended on the liquid surface is arranged in the buffer tank, and the piston divides the buffer tank into an upper regulating area and a lower liquid storage area. A water inlet and a sewage outlet are arranged on the side wall of the lower liquid storage area of ​​the buffer tank. A sludge outlet is arranged at the bottom of the buffer tank, and the sludge outlet is connected to the interior of the sand settling tank through a sludge recovery pipe and a sludge pump;

[0011] Sewage discharge device: includes sewage discharge pipeline and sewage pump, used to discharge sewage after separation from oil sludge.

[0012] As a further improvement of the above technology, the top of the sand settling tank is provided with a sludge scraper device which can extend into the tank body to scrape the sludge from the tank wall. The sludge scraper device includes a rotating handle, a rocker and a scraper connected in sequence. The rocker includes a vertical rod and a tilted rod inclined downward. The top end of the vertical rod is connected to the rotating handle, and the tail end of the tilted rod is movably connected to the scraper. The scraper is close to the inner wall surface of the tank body.

[0013] As a further improvement of the above technology, a screw-shaped sludge output device is provided at the bottom sediment outlet of the sedimentation tank. The screw-shaped sludge output device includes a driving end and a cylindrical sludge containing chamber. A screw connected to the driving end is provided in the cylindrical sludge containing chamber. The driving end drives the screw to rotate to output the sludge.

[0014] As a further improvement of the above technology, the top of the sand settling tank is also provided with a front online sight glass for online checking of the dehydration completion status in the tank. The front online sight glass is a negative pressure extraction device. The negative pressure extraction device is provided with a cavity with a transparent observation window and a circulation pipeline forming a circulation loop with the cavity. The bottom of the cavity is provided with an external connecting pipe and a liquid extraction pipe entering the sand settling tank in sequence.

[0015] As a further improvement of the above technology, a rear online view mirror is provided on the pipeline between the dehydrator and the buffer tank for online inspection of the oil content in the pipeline. The rear online view mirror includes a negative pressure liquid pump, and the negative pressure liquid pump is provided with a liquid containing cavity with a transparent observation window.

[0016] As a further improvement of the above technology, a breathing port is provided on the top of the buffer tank, and a switch valve for automatically closing the breathing port is provided at the breathing port. A valve core for blocking the breathing port is provided in the valve body of the switch valve, and the bottom of the valve core is connected to a valve stem provided with a compression spring or installed with a lever-type touch switch, and the end of the valve stem is connected to a connecting chain, and a heavy hammer is hung at the end of the connecting chain. When the liquid level in the lower liquid storage area rises, the heavy hammer lifts the valve core and closes the breathing port. At this time, the gas in the upper regulating area is compressed, and when the pressure in the upper and lower parts of the buffer tank separated by the piston is equal, the piston stops moving upward.

[0017] As a further improvement of the above technology, the top of the buffer tank is also provided with an exhaust hole, the exhaust hole is connected to an exhaust pipe, a pressure relief hole passes through the piston, and the end of the exhaust pipe is connected to the pressure relief hole.

[0018] As a further improvement of the above technology, the outer ring of the piston in the buffer tank is provided with a circle of magnets, and the outer wall of the buffer tank is provided with a magnetic flap indicator that can cooperate with the magnets to attract and change with the up and down movement of the piston.

[0019] As a further improvement of the above technology, a front-end sewage main pipe is arranged on the pipeline between the dehydrator and the buffer tank, and a multi-way branch pipe is provided at the water inlet end of the front-end sewage main pipe, which is connected to the sand settling tank and the dehydrator at the outlet end of different oil storage tanks respectively, and a water outlet is provided on the other side of the front-end sewage main pipe, which is connected to the water inlet of the buffer tank accordingly.

[0020] As a further improvement of the above technology, a rear-end sewage main pipe is provided on the pipeline at the water outlet end of the buffer tank, and a multi-way branch sewage inlet branch and a sewage discharge pipe are provided at the water inlet end of the rear-end sewage main pipe. The multi-way branch sewage inlet branch is correspondingly connected to the water outlet ends of multiple buffer tanks, and a pressure sensor for real-time monitoring of the pressure in the pipe is provided on the rear-end sewage main pipe. A regulating valve is connected to the discharge outlet of the sewage pump, and the pressure sensor and the regulating valve are connected to the controller.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] (1) The oil tank dehydration system of the present invention performs the dehydration process in a closed pipeline, and will not leak out toxic and harmful gases. During dehydration, toxic and harmful gases will not be discharged into the air, and will not cause pollution to the environment and soil. The system is safe and reliable to use;

[0023] (2) The oil tank dehydration system of the present invention has a sand settling tank added between the dehydrator and the oil tank dehydration port, so that the oil sludge is retained in the settling tank and the oil sludge is regularly cleaned and recovered and reused through a screw-shaped oil sludge output device arranged at the bottom of the sand settling tank, thereby ensuring that the pipeline will not be blocked due to the accumulation or adhesion of oil sludge, ensuring the smooth flow of the pipeline of the entire dehydration system, greatly improving the dehydration efficiency and oil utilization rate, and also greatly improving the service life of the pipeline;

[0024] (3) The oil tank dehydration system of the present invention can further intercept some of the oil sludge remaining in the oil circuit and recycle it due to the addition of a buffer tank, thereby improving the utilization rate of the oil sludge. At the same time, the suspended piston can be lifted up by the incoming liquid and the breathing port can be closed, thereby preventing sewage from being discharged from the breathing port due to piston leakage, and reducing the strength requirement of the piston due to the large liquid surface pressure. In addition, a certain amount of stored liquid is continuously maintained in the buffer tank to ensure that the sewage pump has enough sewage to perform continuous and effective dehydration work, which is convenient for the control of the sewage pump;

[0025] (4) The oil tank dehydration system of the present invention can reserve multiple branches through a front-end sewage pipe or a rear-end sewage pipe with multiple branches, and can dehydrate multiple oil storage tanks, which greatly facilitates the dehydration work of different oil storage tanks and effectively improves the dehydration efficiency;

[0026] (5) The oil tank dehydration system of the present invention can effectively scrape off the oil sludge on the tank wall and reduce the waste caused by the adhesion of oil sludge because the oil sludge scraper device is provided on the sand settling tank;

[0027] (6) The oil tank dehydration system of the present invention is provided with a front online mirror and a rear online mirror. The front online mirror is used to observe whether the water in the oil storage tank has been completely dehydrated, and the rear online mirror is used to observe whether the dehydration contains oil, so as to achieve real-time monitoring and control;

[0028] (7) In the oil tank dehydration system of the present invention, when the pressure sensor on the sewage pipeline detects that the pipeline pressure increases to a set value, the sewage pump will be started, and the flow rate of the sewage pump will be controlled by a frequency converter or a regulating valve to control the pipeline pressure within a set safety range (0.5 to 1.5 meters of water column) to ensure the service life of the pipeline; in addition, a flow meter is added to the pipeline, and pressure sensors are added to the pipeline inlet and outlet to monitor the pressure difference change, understand the pipeline blockage situation, and ensure that it can be cleared in time. All signals are connected to the closed dehydration controller to achieve centralized control, thereby achieving orderly dehydration;

[0029] (8) The oil tank dehydration system of the present invention is provided with a one-way valve to prevent the tanks from being connected, thereby reducing the pressure of the sewage delivery pipeline and keeping the sewage pipeline unobstructed;

[0030] (9) The oil tank dehydration system described in the present invention can solve the dehydration technical problems that are difficult to overcome for petrochemical enterprises, bring better economic benefits to petrochemical enterprises, and has strong practicality. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments:

[0032] Figure 1 This is a schematic structural diagram of a fully enclosed oil tank dehydration system according to Embodiment 1 of the present invention;

[0033] Figure 2 It is a schematic diagram of the structure of the sand settling tank in the first embodiment of the present invention (including the sludge scraper device);

[0034] Figure 3 It is a schematic diagram of the structure of the front online mirror in the first embodiment of the present invention;

[0035] Figure 4 Schematic diagram of the structure of the switch valve for automatically closing the breathing port in the first embodiment of the present invention;

[0036] Figure 5 It is a schematic diagram of the structure of the sand settling tank in the second embodiment of the present invention (including the sludge scraper device);

[0037] Figure 6 Schematic diagram of the structure of the switch valve for automatically closing the breathing port in the third embodiment of the present invention;

[0038] Figure 7 This is a schematic diagram of the installation when the amount of sewage at the bottom of the oil storage tank is small in the fourth embodiment of the present invention;

[0039] Figure 8 This is a schematic diagram of the installation when the amount of sewage at the bottom of the oil tank is small in the fifth embodiment of the present invention. DETAILED DESCRIPTION

[0040] Embodiment 1:

[0041] A fully enclosed oil tank dehydration system according to the present invention comprises an oil storage tank 1 and a dehydrator 2, and also comprises a sand settling tank 3, wherein the sand settling tank 3 is installed between a bottom drain port 11 of the oil storage tank 1 and a water inlet end 21 of the dehydrator 2 through a connecting pipe and a tank root valve 10, and the sand settling tank 3 comprises a top inlet 31 connected to the bottom drain port 11 of the oil storage tank 1, a top outlet 32 ​​connected to the top of the dehydrator 2, and also comprises an outlet 33 for outputting bottom sediment;

[0042] Buffer tank 4: connected to the water outlet end 22 of the dehydrator 2 through a connecting pipe, on which a dehydration valve 5, a one-way valve 6 and an oil-water detection sensor 7 are sequentially arranged, and a suspension piston 8 that can be suspended on the liquid surface is arranged in the buffer tank 4, and the piston 8 divides the buffer tank 4 into an upper regulating area 41 and a lower liquid storage area 42, and a water inlet 43 and a sewage outlet 44 are arranged on the side wall of the lower liquid storage area 42 of the buffer tank 4, and an oil sludge outlet 45 is arranged at the bottom of the buffer tank 4, and the oil sludge outlet 45 is connected to the interior of the sand settling tank 3 through an oil sludge recovery pipe 46 and an oil sludge pump 50, so that the oil sludge in the buffer tank 4 can be recycled to the interior of the sand settling tank 3 for oil sludge output treatment;

[0043] The sewage discharge device includes a sewage discharge pipeline and a sewage pump 60, which is used to discharge the sewage after being separated from the oil sludge.

[0044] like Figures 1 to 3 As shown, the desilting tank 3 is provided with a sludge scraper device 9 on the top of the desilting tank 3 which can extend into the tank body to scrape the sludge from the tank wall. The sludge scraper device 9 includes a rotating handle 91, a rocker and a scraper 92 connected in sequence. The rocker includes a vertical rod 93 and a tilted rod 94 tilted downward. The top end of the vertical rod 93 is connected to the rotating handle 91, and the rear end of the tilted rod 94 is movably connected to the scraper 92. The scraper 92 is in close contact with the inner wall surface of the tank body to scrape the sludge from the inner wall of the desilting tank 3, thereby effectively reducing the sludge adhering to the inner wall surface of the desilting tank 3.

[0045] like Figure 2 As shown, the scraper 92 is a triangular scraper, and its right-angled side is close to the inner wall of the sand settling tank 3. The upright rod 93 and the inclined rod 94 of the rocker are relatively fixedly connected. When mud scraping is needed, the rocker and the scraper 92 can be rotated together by rotating the handle 91 to scrape the mud, which is simple and convenient.

[0046] like Figure 1 , Figure 2 As shown, in the present invention, a screw-shaped sludge output device 12 is provided at the bottom sediment outlet 33 of the sedimentation tank 3, and the screw-shaped sludge output device 12 includes a driving end 121 and a cylindrical sludge containing chamber 122. A screw 123 connected to the driving end is provided in the cylindrical sludge containing chamber 122. The driving end 121 drives the screw 123 to rotate to output the sludge. The output sludge can be recycled and reused, which greatly improves the utilization rate of the oil.

[0047] like Figure 1 , Figure 3 As shown, the top of the sand settling tank 3 is also provided with a front online sight glass for online checking the completion of dehydration in the tank. The front online sight glass is a negative pressure extraction device 13. The negative pressure extraction device 13 is provided with a cavity 131 with a transparent observation window and a circulation pipeline 132 forming a circulation loop with the cavity 131. The bottom of the cavity 131 is provided with an external connecting pipe 133 and a liquid extraction pipe 134 entering the sand settling tank 3 in sequence. The liquid in the sand settling tank 3 is extracted by the negative pressure extraction device 13 for observation. The color of the liquid can be used to distinguish whether it contains more oil or water, and further distinguish the dehydration situation in the oil storage tank 1.

[0048] like Figure 1 As shown, a rear online view mirror is provided on the pipeline between the dehydrator 2 and the buffer tank 4 for online checking of the oil content in the pipeline. The rear online view mirror includes a negative pressure liquid pump 14. The negative pressure liquid pump 14 is provided with a liquid containing cavity 141 with a transparent observation window. The rear online view mirror is used to observe whether the pipeline contains oil, so as to achieve real-time monitoring and control.

[0049] like Figure 4 As shown, a breathing port 47 is provided at the top of the buffer tank 4, and a switch valve 15 for automatically closing the breathing port 47 is provided at the breathing port 47, a valve core 151 for blocking the breathing port is provided in the valve body of the switch valve 15, the bottom of the valve core 151 is connected to a valve stem 153 provided with a compression spring 152, the end of the valve stem 153 is connected to a connecting chain 154, and a heavy hammer 20 is suspended at the end of the connecting chain 154, and when the liquid level in the lower liquid storage area 42 of the piston 8 rises, the heavy hammer 20 lifts the valve core 151 and then closes the breathing port. At this time, the gas in the upper regulating area 41 is compressed, and the piston 8 stops moving up, which effectively prevents sewage from being discharged from the breathing port 47 due to leakage of the piston 8, and also reduces the high strength requirement for the piston due to excessive liquid surface pressure.

[0050] like Figure 1As shown, the top of the buffer tank 4 is also provided with an exhaust hole 48, and an exhaust pipe 49 is connected to the exhaust hole 48. A pressure relief hole 81 is also passed through the piston 8, and the end of the exhaust pipe 49 is connected to the pressure relief hole 81. The apertures of the exhaust hole 48 and the pressure relief hole 81 are both relatively small.

[0051] In addition, in order to better observe the height of the liquid level in the buffer tank 4, a circle of magnets 16 is provided on the outer ring of the piston 8 in the buffer tank 4, and the outer wall of the buffer tank 4 is provided with a magnetic flap indicator 17 which can cooperate with the magnet 16 to attract and change with the up and down movement of the piston 8. In this way, the height of the liquid level in the buffer tank 4 can be detected in real time from the height position of the magnetic flap indicator 17.

[0052] like Figure 1 As shown, a front-end sewage main pipe 30 is arranged on the pipeline between the dehydrator 2 and the buffer tank 4, and a multi-way branch pipe 301 is provided at the water inlet end of the front-end sewage main pipe 30. The multi-way branch pipe 301 can be connected to the sand settling tank 3 and the dehydrator 2 at the outlet end of different oil storage tanks 1 to perform dehydration work of a tank group, and the working efficiency is high. A water outlet 302 is provided on the other side of the front-end sewage main pipe 30, which is correspondingly connected to the water inlet 43 of the buffer tank 4.

[0053] A rear-end sewage main pipeline 40 is provided on the pipeline at the water outlet end of the buffer tank 4, and a multi-way branch sewage inlet branch 401 and a sewage discharge pipe 402 are provided at the water inlet end of the rear-end sewage main pipeline 40. The multi-way branch sewage inlet branch 401 is correspondingly connected to the water outlet ends of multiple buffer tanks 4. A pressure sensor 70 for real-time monitoring of the pressure in the pipe is provided on the rear-end sewage main pipeline 40. A regulating valve 80 is connected to the discharge port of the sewage pump 60. The pressure sensor 70 and the regulating valve 80 are connected to the controller 90. The flow rate of the sewage pump is controlled by the variable frequency controller 90 or the regulating valve 80, and the pipeline pressure is controlled within the set safety range (0.5 to 1.5 meters of water column) to ensure the service life of the pipeline.

[0054] In the present invention, the dehydrator 2 can be any conventional dehydrator, such as Figure 2 As shown, the body of the dehydrator 2 is installed on the system pipeline at an angle, which ensures that the height of the water inlet end 21 is at the highest position of the dehydrator 2, while the water outlet end 22 is at the lowest position of the dehydrator 2. By utilizing the characteristic that the specific gravity of oil is less than that of water, the oil and water can be separated to the greatest extent, so that a part of the oil floating on the water surface can flow back to the sand settling tank 3, and the sewage flows to through the water outlet end 22, so that the purpose of oil-water separation and smooth dehydration can be better achieved.

[0055] The working process of the fully enclosed oil tank dehydration system of the present invention is described in detail below:

[0056] First, the sewage is discharged from the drain port 11 at the bottom of the oil storage tank 1 to the sand settling tank 3. At this time, the sand in the sewage will settle to the bottom and pass through the screw-shaped oil sludge output device 12, while the oil and water with lighter specific gravity will enter the dehydrator 2;

[0057] Secondly, after the dehydration treatment in the dehydrator 2, the wastewater enters the buffer tank 4, where the oil sludge contained therein is further intercepted and discharged. At the same time, the air pressure in the buffer tank 4 is lowered and buffered by a suspended piston 8 in the buffer tank 4 to ensure that the liquid discharged from the buffer tank 4 contains less oil or other gas impurities, thereby achieving the purpose of purifying sewage.

[0058] Finally, the relatively clean sewage is discharged through the sewage pump 60, which will not cause pollution to the environment and soil, and is safe and reliable to use.

[0059] Embodiment 2:

[0060] This embodiment is basically the same as the first embodiment, except that: Figure 5 As shown, the scraper 92' is in the shape of a straight plate, and the upright rod 93' and the tilting rod 94' of the rocker are movably connected. By rotating the handle 91, the rocker and the scraper 92 can also be driven to rotate together, thereby performing effective mud scraping work.

[0061] Embodiment three:

[0062] This embodiment is basically the same as the first embodiment, except that: Figure 6 As shown, the breathing port 47 is provided with a switch valve 15 which can automatically close the breathing port 47, and a valve core 151 for blocking the breathing port is provided in the valve body of the switch valve 15, and the bottom of the valve core 151 is connected to a valve stem 153 provided with a lever-type touch switch 152', and the end of the valve stem 153 is connected to a connecting chain 154, and a heavy hammer 20 is suspended at the end of the connecting chain 154. When the liquid level of the lower liquid storage area 42 rises, the heavy hammer 20 lifts the valve core 151 and closes the breathing port 47, and the piston 8 stops moving upward.

[0063] Embodiment 4:

[0064] This embodiment is basically the same as the first embodiment, except that: Figure 7 As shown, the amount of sewage at the bottom of the oil storage tank 1 is relatively small. At this time, the sewage at the bottom of the tank can be smoothly discharged by connecting the tank root valve 10 through the elbow 100.

[0065] Embodiment five:

[0066] This embodiment is basically the same as the first embodiment, except that: Figure 8As shown, when the oil storage tank 1 is located at a lower geographical location and is not convenient for direct installation, the sewage is sucked out through a siphon type liquid suction device 110 and then connected to the subsequent dehydration pipeline.

[0067] The present invention is not limited to the above-mentioned embodiments. Any changes or modifications to the present invention do not depart from the spirit and scope of the present invention. If these changes and modifications fall within the scope of the claims and equivalent technologies of the present invention, the present invention is also meant to include these changes and modifications.

Claims

1. A fully enclosed oil tank dehydration system, comprising an oil storage tank and a dehydrator, characterized in that: Also includes: Sand settling tank: installed between the bottom drain port of the oil storage tank and the water inlet end of the dehydrator through a connecting pipe, the sand settling tank includes a top inlet connected to the bottom drain port of the oil storage tank, a top outlet connected to the top of the dehydrator, and a bottom outlet for outputting silt; Buffer tank: connected to the water outlet end of the dehydrator through a connecting pipe, on which a dehydration valve, a one-way valve and an oil-water detection sensor are arranged in sequence. A suspension piston that can be suspended on the liquid surface is arranged in the buffer tank, and the piston divides the buffer tank into an upper regulating area and a lower liquid storage area. A water inlet and a sewage outlet are arranged on the side wall of the lower liquid storage area of ​​the buffer tank. A sludge outlet is arranged at the bottom of the buffer tank, and the sludge outlet is connected to the interior of the sand settling tank through a sludge recovery pipe and a sludge pump; Sewage discharge device: including sewage discharge pipeline and sewage pump, used to discharge sewage after separation from oil sludge; The top of the sand settling tank is provided with a sludge scraper device which can extend into the tank body to scrape the sludge from the tank wall. The sludge scraper device comprises a rotating handle, a rocker and a scraper connected in sequence. The rocker comprises a vertical rod and a tilting rod inclined downward. The top end of the vertical rod is connected to the rotating handle, and the bottom end of the tilting rod is movably connected to the scraper. The scraper is in close contact with the inner wall surface of the tank body. A screw-shaped oil sludge output device is provided at the bottom sediment outlet of the sedimentation tank, and the screw-shaped oil sludge output device includes a driving end and a cylindrical oil sludge containing chamber, and a screw connected to the driving end is provided in the cylindrical oil sludge containing chamber, and the driving end drives the screw to rotate to output the oil sludge; A breathing port is provided on the top of the buffer tank, and a switch valve for automatically closing the breathing port is provided at the breathing port. A valve core for blocking the breathing port is provided in the valve body of the switch valve, and a valve stem provided with a compression spring or a lever-type touch switch is connected to the bottom of the valve core, and a connecting chain is connected to the end of the valve stem, and a heavy hammer is hung at the end of the connecting chain. When the piston rises with the liquid level in the lower liquid storage area, the heavy hammer pushes up and the valve core closes the breathing port; The top of the buffer tank is also provided with an exhaust hole, the exhaust hole is connected to an exhaust pipe, the piston is penetrated by a pressure relief hole, and the end of the exhaust pipe is connected to the pressure relief hole; The outer ring of the piston in the buffer tank is provided with a circle of magnets, and the outer wall surface of the buffer tank is provided with a magnetic flap indicator which can be attracted by the magnet and change with the up and down movement of the piston.

2. The fully enclosed oil tank dehydration system according to claim 1 is characterized in that: The top of the sand settling tank is also provided with a front online sight glass for online checking of the dehydration completion status in the tank. The front online sight glass is a negative pressure extraction device, which is provided with a cavity with a transparent observation window and a circulation pipeline forming a circulation loop with the cavity. The bottom of the cavity is provided with an external connecting pipe and a liquid extraction pipe entering the sand settling tank in sequence.

3. The fully enclosed oil tank dehydration system according to claim 1 is characterized in that: A rear online viewing mirror for online inspection of the oil content in the pipeline is provided on the pipeline between the dehydrator and the buffer tank. The rear online viewing mirror includes a negative pressure liquid pump, and the negative pressure liquid pump is provided with a liquid containing cavity with a transparent observation window.

4. The fully enclosed oil tank dehydration system according to claim 1 is characterized in that: A front-end sewage main pipe is arranged on the pipeline between the dehydrator and the buffer tank, and a multi-way branch pipe is arranged at the water inlet end of the front-end sewage main pipe, which is connected to the sand settling tank and the dehydrator at the outlet end of different oil storage tanks respectively, and a water outlet is arranged on the other side of the front-end sewage main pipe, which is connected to the water inlet of the buffer tank accordingly.

5. The fully enclosed oil tank dehydration system according to claim 1 is characterized in that: A rear-end sewage main pipeline is provided on the pipeline at the water outlet end of the buffer tank, and a multi-way branch sewage inlet branch and a sewage discharge pipe are provided at the water inlet end of the rear-end sewage main pipeline. The multi-way branch sewage inlet branch is correspondingly connected to the water outlet ends of multiple buffer tanks. A pressure sensor for real-time monitoring of the pressure in the pipe is provided on the rear-end sewage main pipeline, and a regulating valve is connected to the discharge port of the sewage pump. The pressure sensor and the regulating valve are connected to a controller.

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