Oil tank cleaning system and cleaning method

Abstract

The present invention relates to the technical field of oil tank cleaning, and discloses an oil tank cleaning system and a cleaning method. The oil tank cleaning system includes a suction device, which includes a vacuum pump, a vacuum tank and a primary filter. The vacuum pump is used to extract the oil in the oil tank and temporarily store it in the vacuum tank after filtering through the primary filter; the cleaning device includes a booster pump and a cleaning nozzle. The cleaning nozzle can be inserted into the oil tank and can be raised and lowered relative to the oil tank and rotated 360 degrees to spray and clean the inner wall of the oil tank. The present invention filters the oil in the oil tank through the primary filter, and then pressurizes it through the booster pump. The pressurized oil is used to clean the ground tank without introducing foreign impurities. After cleaning the ground tank, there is no need to dry the ground tank, which simplifies the cleaning process of the ground tank; there is no need for cleaning workers to enter the ground tank, which ensures the personal safety of the cleaning workers, reduces manual intervention in the ground tank cleaning process, and improves the automation of ground tank cleaning.

Description

Technical Field

[0001] The present invention relates to the technical field of oil tank cleaning, and in particular to an oil tank cleaning system and a cleaning method. Background Art

[0002] Most of the oil tanks at gas stations are buried below the ground, usually called buried oil tanks, or ground tanks for short. Ground tanks need to be cleaned regularly, and currently they are usually cleaned manually. Specifically, the remaining oil in the ground tank is first pumped out, and then the cleaning operator wears a respirator to enter the tank, manually shovel out the dirty oil and sludge in the tank, and then rinse it with a pressure water gun.

[0003] The above method uses a cleaning fluid such as water to clean the oil tank, which has the following disadvantages:

[0004] (1) During the cleaning operation, the cleaning workers are completely in an environment full of explosive and toxic gases, and the safety of the operation is poor.

[0005] (2) After the manual cleaning operation is completed, the tank is still filled with explosive and toxic gases, and subsequent inspection workers still need to wear respirators to conduct relevant inspections.

[0006] (3) When using water to clean the floor tank, the water and the oil in the floor tank are mixed to form mixed oil, which needs to be separated; and after cleaning, it is necessary to manually go down into the floor tank to check and clean it, remove the residue, and ventilate and dry the floor tank. The cleaning process of the floor tank is relatively complicated. Summary of the invention

[0007] The purpose of the present invention is to provide an oil tank cleaning system and a cleaning method to reduce human intervention in the oil tank cleaning process and improve the degree of automation of oil tank cleaning; use the oil in the ground tank to clean the oil tank, avoid introducing foreign impurities, and simplify the cleaning process.

[0008] To achieve this object, the present invention adopts the following technical solutions:

[0009] An oil tank cleaning system, comprising:

[0010] A suction device, comprising a vacuum pump, a vacuum tank and a primary filter, wherein the oil tank, the primary filter, the vacuum tank and the vacuum pump are sequentially connected, and the vacuum pump is used to extract the oil in the oil tank and temporarily store it in the vacuum tank after filtering through the primary filter;

[0011] The cleaning device comprises a booster pump and a cleaning nozzle, wherein the vacuum tank, the booster pump and the cleaning nozzle are connected in sequence, and the cleaning nozzle can be inserted into the oil tank and can be raised and lowered relative to the oil tank and rotated 360 degrees to spray and clean the inner wall of the oil tank.

[0012] As a preferred technical solution of the above oil tank cleaning system, it also includes:

[0013] A protective gas delivery device, used to replace the oil and gas in the oil tank, and the air or oil and gas in the vacuum tank and the primary filter with protective gas;

[0014] The gas detector is used to detect the combustible gas content and oxygen content in the oil tank, the vacuum tank, and the primary filter.

[0015] As a preferred technical solution of the above-mentioned oil tank cleaning system, it also includes an oil-gas separation device that can be connected to the oil tank, the vacuum tank and the primary filter, for separating the oil and gas displaced by the oil tank, the vacuum tank and the primary filter, and returning the separated oil to the oil tank.

[0016] As a preferred technical solution of the above-mentioned oil tank cleaning system, it also includes a secondary filter component, and the booster pump can be connected to the cleaning nozzle through the secondary filter component.

[0017] As a preferred technical solution of the above-mentioned oil tank cleaning system, it also includes a three-stage filter, and the secondary filter component can be directly connected to the cleaning nozzle, or connected to the cleaning nozzle through the three-stage filter.

[0018] As a preferred technical solution of the above oil tank cleaning system, it also includes:

[0019] A first oil level detection unit, used for detecting the oil level in the oil tank;

[0020] A temporary oil storage tank, which can be connected to the oil tank and can also be selectively connected to the protective gas delivery device or the vacuum pump.

[0021] As a preferred technical solution of the above-mentioned oil tank cleaning system, the temporary oil storage tank can also be connected to the oil tank through the three-stage filter.

[0022] As a preferred technical solution of the above-mentioned oil tank cleaning system, it also includes an oil quality detector for detecting the quality of the oil in the temporary oil storage tank and / or the vacuum tank.

[0023] As a preferred technical solution of the above-mentioned oil tank cleaning system, the temporary oil storage tank can be connected to the oil inlet of the fuel dispenser through a fueling pipeline, and a fueling switch valve is provided on the fueling pipeline.

[0024] The present invention also provides an oil tank cleaning method, which adopts the above-mentioned oil tank cleaning system, uses a vacuum pump to extract the oil in the oil tank and sends it into a vacuum tank after filtering, uses a booster pump to pressurize the oil in the vacuum tank and sends the pressurized oil to the cleaning nozzle, and utilizes the lifting and 360° rotation of the cleaning nozzle to perform high-pressure flushing on the inner wall of the oil tank.

[0025] Beneficial effects of the present invention: When the oil tank filtration system provided by the present invention is used to clean the ground tank, the oil in the oil tank is filtered through a primary filter, and then pressurized by a booster pump, and the pressurized oil is used to clean the ground tank, without introducing foreign impurities. After the ground tank is cleaned, there is no need to dry the ground tank, which simplifies the cleaning process of the ground tank; and there is no need for cleaning workers to enter the ground tank, which ensures the personal safety of cleaning workers, reduces manual intervention in the ground tank cleaning process, and improves the automation of ground tank cleaning. The system can clean the oil tank without affecting the normal sale of oil in the cleaned oil tank. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments of the present invention. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the contents of the embodiments of the present invention and these drawings without paying any creative work.

[0027] Figure 1 is a hydraulic principle diagram of an oil tank cleaning system provided by an embodiment of the present invention;

[0028] Figure 2 It is a flow chart of the oil tank cleaning method provided by an embodiment of the present invention.

[0029] In the figure:

[0030] 1. Ground tank;

[0031] 21. Primary filter; 22. Secondary filter; 23. Spare secondary filter; 24. Third-stage filter;

[0032] 3. Vacuum tank; 4. Booster pump; 5. Temporary oil storage tank; 6. Oil and gas separation device;

[0033] 71. Liquid nitrogen tank; 72. Heat exchanger;

[0034] 81. Air pump; 82. Gas detector;

[0035] 90. vacuum pump; 91. first exhaust switch valve; 92. second exhaust switch valve;

[0036] 100, main gas pipeline; 101, first gas pipeline; 102, second gas pipeline; 103, third gas pipeline; 104, fourth gas pipeline; 105, fifth gas pipeline; 106, sixth gas pipeline; 107, seventh gas pipeline; 108, eighth gas pipeline; 109, ninth gas pipeline; 110, tenth gas pipeline; 111, eleventh gas pipeline; 112, twelfth gas pipeline;

[0037] 200, first liquid nitrogen switch valve; 201, nitrogen switch valve; 202, second liquid nitrogen switch valve;

[0038] 301, first replacement switch valve; 302, second replacement switch valve; 303, third replacement switch valve; 304, fourth replacement switch valve; 305, fifth replacement switch valve; 306, sixth replacement switch valve; 307, seventh replacement switch valve; 308, eighth replacement switch valve; 309, ninth replacement switch valve; 310, tenth replacement switch valve;

[0039] 401, first emptying switch valve; 402, second emptying switch valve; 403, third emptying switch valve; 404, fourth emptying switch valve; 405, fifth emptying switch valve; 406, sixth emptying switch valve;

[0040] 501, first oil circuit; 502, second oil circuit; 503, third oil circuit; 504, first switch valve; 505, second switch valve; 506, third switch valve;

[0041] 601, first separation switch valve; 602, second separation switch valve; 603, oil return valve;

[0042] 701, first cleaning switch valve; 702, second cleaning switch valve; 703, third cleaning switch valve; 704, fourth cleaning switch valve; 705, fifth cleaning switch valve; 706, sixth cleaning switch valve; 707, seventh cleaning switch valve; 708, eighth cleaning switch valve; 709, ninth cleaning switch valve; 710, tenth cleaning switch valve;

[0043] 801, slag discharge valve; 802, refueling switch valve. DETAILED DESCRIPTION

[0044] In order to make the technical problems solved by the present invention, the technical solutions adopted and the technical effects achieved clearer, the technical solutions of the present invention are further described below in conjunction with the accompanying drawings and through specific implementation methods. It is understood that the specific embodiments described herein are only used to explain the present invention, rather than to limit the present invention. It should also be noted that, for the convenience of description, only the parts related to the present invention are shown in the accompanying drawings, not all.

[0045] like Figure 1 As shown, this embodiment provides an oil tank cleaning system. The oil tank in this embodiment is an underground oil tank, namely, an underground tank 1. The above-mentioned oil tank cleaning system is introduced below by taking the cleaning of the underground tank 1 as an example.

[0046] The oil tank cleaning system includes a suction device and a cleaning device, wherein the suction device includes a vacuum pump 90, a vacuum tank 3 and a primary filter 21, the floor tank 1, the primary filter 21, the vacuum tank 3 and the vacuum pump 90 are connected in sequence, and the vacuum pump 90 is used to extract the oil in the floor tank 1 and temporarily store it in the vacuum tank 3 after filtering through the primary filter 21; the cleaning device includes a booster pump 4 and a cleaning nozzle, the vacuum tank 3, the booster pump 4 and the cleaning nozzle are connected in sequence, and the cleaning nozzle can be inserted into the floor tank 1, and can be raised and lowered relative to the floor tank 1 and rotated 360° to spray and clean the inner wall of the floor tank 1.

[0047] When the floor tank 1 needs to be cleaned, the oil in the floor tank 1 can be extracted by the vacuum pump 90 and temporarily stored in the vacuum tank 3 after being filtered by the primary filter 21, and then the oil in the vacuum tank 3 can be extracted by the booster pump 4 and the pressurized oil can be sent to the cleaning nozzle. The lifting and 360-degree rotation of the cleaning nozzle can realize all-round cleaning of the floor tank 1. Moreover, the dirty oil formed by cleaning can be sent to the cleaning nozzle again after being filtered by the primary filter 21 to realize recycling.

[0048] In this embodiment, the oil in the floor tank 1 is pressurized after being filtered, and the floor tank 1 is cleaned with the pressurized oil without introducing foreign impurities. After the floor tank 1 is cleaned, there is no need to dry the floor tank 1, which simplifies the cleaning process of the floor tank 1. In addition, there is no need for cleaning workers to enter the floor tank 1, which ensures the personal safety of the cleaning workers, reduces manual intervention in the cleaning process of the floor tank 1, and improves the degree of automation of the cleaning of the floor tank 1.

[0049] Specifically, the oil inlet of the first-level filter 21 is connected to the ground tank 1, the oil outlet of the first-level filter 21 is connected to the oil inlet of the vacuum tank 3, the oil inlet of the first-level filter 21 is provided with a first cleaning switch valve 701, and the oil outlet of the first-level filter 21 is provided with a second cleaning switch valve 702; the first air outlet of the vacuum tank 3 is connected to the air inlet of the vacuum pump 90, and the first exhaust switch valve 91 is provided on the connecting pipeline between the first air outlet of the vacuum tank 3 and the air inlet of the vacuum pump 90.

[0050] The oil outlet of the vacuum tank 3 is connected to the oil inlet of the booster pump 4. The oil outlet of the vacuum tank 3 is provided with a third cleaning switch valve 703. The secondary filter assembly includes a secondary filter 22 and a spare secondary filter 23 arranged in parallel therewith. The oil inlet of the secondary filter 22 is provided with a fourth cleaning switch valve 704. The oil outlet of the secondary filter 22 is provided with a fifth cleaning switch valve 705. The oil inlet of the spare secondary filter 23 is provided with a sixth cleaning switch valve 706. The oil outlet of the spare secondary filter 23 is provided with a seventh cleaning switch valve 707. The oil outlet of the secondary filter 22 and the oil outlet of the spare secondary filter 23 are connected to the ground tank 1 through a cleaning pipeline after merging.

[0051] Pressure sensors are provided at the oil inlet of the spare secondary filter 23 and the oil inlet of the secondary filter 22. During the filtering process using the secondary filter 22, the corresponding pressure sensors are used to detect in real time whether the secondary filter 22 is blocked. When the secondary filter 22 is blocked, the sixth cleaning switch valve 706 and the seventh cleaning switch valve 707 are opened first, and then the fourth cleaning switch valve 704 and the fifth cleaning switch valve 705 are closed, and then the secondary filter 22 is replaced. Other methods can also be used to detect whether the secondary filter 22 and the spare secondary filter 23 are blocked, such as detecting the flow rate of oil passing through the outlet of the secondary filter 22, which will not be described in detail here.

[0052] When it is necessary to pump the oil in the ground tank 1 into the vacuum tank 3, the first cleaning switch valve 701, the second cleaning switch valve 702 and the first exhaust switch valve 91 are opened, and the vacuum pump 90 is operated to gradually reduce the pressure in the ground tank 1 and the vacuum tank 3, so that the oil in the ground tank 1 enters the vacuum tank 3 after being filtered by the primary filter 21.

[0053] In order to ensure that there is enough oil in the vacuum tank 3 for cleaning the floor tank 1, a second oil level detection unit is provided in the vacuum tank 3. In this embodiment, the second oil level detection unit adopts a liquid level sensor for detecting the liquid level in the vacuum tank 3. Before cleaning the floor tank 1 and in the process of pumping the oil in the floor tank 1 into the vacuum tank 3, the vacuum pump 90 needs to be stopped when the liquid level in the vacuum tank 3 reaches a first preset liquid level.

[0054] After the liquid level of the oil in the vacuum tank 3 reaches the first preset liquid level, the third cleaning switch valve 703, the fourth cleaning switch valve 704, the fifth cleaning switch valve 705 and the eighth cleaning switch valve 708 are opened, and the sixth cleaning switch valve 706 and the seventh cleaning switch valve 707 are closed. The booster pump 4 filters the oil in the vacuum tank 3 through the secondary filter 22 and sends it to the cleaning nozzle. The floor tank 1 is cleaned by the lifting and 360° rotation of the cleaning nozzle. The timing is 5 minutes, and the booster pump 4 stops working. At this time, a cleaning cycle is completed. It should be noted that in other embodiments, the duration of a cleaning cycle is not limited to 5 minutes and can be set according to actual needs.

[0055] During the cleaning process of the floor tank 1, once the liquid level in the vacuum tank 3 is lower than the third preset liquid level, the oil in the floor tank 1 is sent to the vacuum tank 3 by the vacuum pump 90 while the floor tank 1 is being cleaned until the liquid level in the vacuum tank 3 reaches the first preset liquid level.

[0056] Furthermore, the oil tank cleaning system further includes an oil analyzer. After completing a cleaning cycle, the oil in the ground tank 1 is sampled to detect whether the quality of the sample is qualified. If it is unqualified, the next cleaning cycle is performed. The number of cleaning cycles is not limited. If the quality of the sample taken from the ground tank 1 is qualified, it is considered that the cleaning of the ground tank 1 is completed.

[0057] After the cleaning of the ground tank 1 is completed, the oil in the vacuum tank 3 needs to be sent back to the ground tank 1. In order to improve the quality of the oil sent to the ground tank 1, the present embodiment further provides a three-stage filter 24 connected in parallel with the cleaning pipeline. The oil inlet of the three-stage filter 24 is provided with a ninth cleaning switch valve 709, the oil outlet of the three-stage filter 24 is provided with a tenth cleaning switch valve 710, and the cleaning pipeline is provided with an eighth cleaning switch valve 708 connected in parallel with the three-stage filter 24. When the oil in the vacuum tank 3 is sent back to the ground tank 1 after cleaning, the ninth cleaning switch valve 709 and the tenth cleaning switch valve 710 are opened, and the eighth cleaning switch valve 708 is closed, so that the oil in the vacuum tank 3 is sent back to the ground tank 1 through the booster pump 4, the second-stage filter 22, and the third-stage filter 24 in sequence.

[0058] It should be noted that, during the cleaning process of the ground tank 1, the oil filtered through the secondary filter assembly can actually meet the cleaning requirements. Therefore, in order to reduce costs, during the cleaning process of the ground tank 1, the ninth cleaning switch valve 709 and the tenth cleaning switch valve 710 are both in a closed state, and the eighth cleaning switch valve 708 is in an open state.

[0059] In this embodiment, the filtering accuracies of the primary filter 21 , the secondary filter 22 and the tertiary filter 24 increase in sequence, and the filtering accuracy of the spare secondary filter 23 is equal to the filtering accuracy of the secondary filter 22 .

[0060] Furthermore, in order to provide a safe and stable working environment for the cleaning operation of the ground tank 1, a protective gas delivery device is added in this embodiment, and the protective gas delivery device is used to replace the oil and gas in the ground tank 1 with protective gas, as well as the air or oil and gas in the connecting pipeline between the vacuum tank 3, the primary filter 21, the secondary filter assembly, the tertiary filter 24, and the vacuum tank 3 and the ground tank 1. The protective gas in this embodiment is nitrogen. In other embodiments, non-flammable and non-combustible gas such as inert gas can also be used to replace nitrogen.

[0061] Specifically, the protective gas delivery device includes a liquid nitrogen tank 71, a heat exchanger 72 and a delivery pump, wherein the delivery pump is used to deliver the liquid nitrogen in the liquid nitrogen tank 71 to the heat exchanger 72, and the heat exchanger 72 converts the liquid nitrogen into nitrogen gas by using the heat exchange principle. The outlet of the heat exchanger 72 can be connected to the ground tank 1 to deliver the nitrogen gas into the ground tank 1 to replace the oil and gas in the ground tank 1. It should be noted that the above-mentioned heat exchanger 72 can be an air heat exchanger or an electrically heated water bath heat exchanger, preferably an electrically heated water bath heat exchanger.

[0062] More specifically, the liquid nitrogen tank 71 is connected to the heat exchanger 72 through the liquid nitrogen delivery pipelines d1 and d2, a first liquid nitrogen switch valve 200 is provided on the liquid nitrogen delivery pipeline, and a nitrogen switch valve 201 is provided at the outlet of the heat exchanger 72. The liquid nitrogen delivery pipeline is wrapped with an insulation layer to prevent the liquid nitrogen in the liquid nitrogen delivery pipeline from exchanging heat with the air and heating up when the first liquid nitrogen switch valve 200 and the nitrogen switch valve 201 are closed, resulting in an increase in pressure in the liquid nitrogen delivery pipeline, thereby causing the pipeline to burst.

[0063] Before cleaning the ground tank 1, nitrogen is used to replace the oil and gas in the ground tank 1, as well as the air in the vacuum tank 3, the primary filter 21, the secondary filter assembly, and the tertiary filter 24; after cleaning the ground tank 1, nitrogen is used to replace the oil and gas in the vacuum tank 3, the primary filter 21, the secondary filter assembly, and the tertiary filter 24, thereby reducing the content of combustible gas and oxygen in the entire oil tank cleaning system, thereby providing a safe and stable working environment for the cleaning operation of the ground tank 1 and the normal operation of the ground tank 1 after cleaning.

[0064] Furthermore, the oil tank cleaning system also includes an air pump 81 and a gas detector 82, wherein the air pump 81 is used to send the displaced air or oil gas to the gas detector 82, and the gas detector 82 is used to detect the combustible gas content and oxygen content in the ground tank 1, the vacuum tank 3, the primary filter 21, the secondary filter 22, the tertiary filter 24, and the connecting pipeline between the vacuum tank 3 and the ground tank 1. When the air or oil gas in the ground tank 1, the vacuum tank 3, the primary filter 21, the secondary filter 22, and the tertiary filter 24 are displaced by nitrogen, the oxygen content and combustible gas content in the displaced air or oil gas are detected in real time by the gas detector 82.

[0065] Preferably, the air pump 81 is an explosion-proof air pump, and the air pump 81 is located upstream of the gas detector 82. In other embodiments, the air pump 81 can also be located downstream of the gas detector 82.

[0066] Specifically, the outlet of the heat exchanger 72 is connected to the main gas pipeline 100, which is connected to the air inlet of the ground tank 1 through the first gas pipeline 101, and the first gas pipeline 101 is provided with a first replacement switch valve 301. The air outlet of the ground tank 1 is connected to the inlet of the air pump 81 through the second gas pipeline 102, and the second gas pipeline 102 is provided with a second replacement switch valve 302. After the cleaning of the ground tank 1 is completed, the nitrogen switch valve 201, the first replacement switch valve 301 and the second replacement switch valve 302 are opened, and the oil and gas in the ground tank 1 are replaced by nitrogen until the combustible gas content in the replaced oil and gas detected by the gas detector 82 is lower than the first preset content and the oxygen content is lower than the second preset content, then the replacement of the oil and gas in the ground tank 1 is completed.

[0067] The main gas pipeline 100 can be connected to the air inlet of the primary filter 21 through the third gas pipeline 103, and the third gas pipeline 103 is provided with a third replacement switch valve 303. The air outlet of the primary filter 21 can be connected to the inlet of the air pump 81 through the fourth gas pipeline 104, and the fourth gas pipeline 104 is provided with a fourth replacement switch valve 304. The primary filter 21 is provided with a first drain port, and the first drain port is provided with a first drain switch valve 401.

[0068] When replacing the air in the primary filter 21 before starting to clean the ground tank 1, close the first cleaning switch valve 701 and the second cleaning switch valve 702, open the nitrogen switch valve 201, the third replacement switch valve 303, the fourth replacement switch valve 304 and the first emptying switch valve 401, and use nitrogen to replace the air in the primary filter 21. Part of the replaced air is directly discharged into the atmosphere through the first exhaust port, and part of the air is sent to the gas detector 82 through the air pump 81. The gas detector 82 is used to detect the combustible gas content and oxygen content in the ground tank 1 in real time until the replaced combustible gas content is lower than the first preset content and the oxygen content is lower than the second preset content. Then, the replacement of the air in the primary filter 21 is completed. When the oil and gas in the primary filter 21 are replaced after the cleaning of the ground tank 1 is completed, the first cleaning switch valve 701, the second cleaning switch valve 702 and the first emptying switch valve 401 are closed, and the nitrogen switch valve 201, the third replacement switch valve 303 and the fourth replacement switch valve 304 are opened. The oil and gas in the primary filter 21 are replaced with nitrogen, and the replaced oil and gas are sent to the gas detector 82 through the air pump 81 until the replaced combustible gas content is lower than the first preset content and the oxygen content is lower than the second preset content, thereby completing the replacement of the oil and gas in the primary filter 21.

[0069] The second gas outlet of the vacuum tank 3 can be connected to the inlet of the air pump 81 through the fifth gas pipeline 105, the fifth gas pipeline 105 is provided with a fifth replacement switch valve 305, and the vacuum tank 3 is provided with a second emptying port, and the second emptying port is provided with a second emptying switch valve 402. Before starting to clean the ground tank 1 and after replacing the air in the primary filter 21 with nitrogen, the air in the vacuum tank 3 is replaced. Specifically, the nitrogen switch valve 201, the third replacement switch valve 303, the second cleaning switch valve 702, the fifth replacement switch valve 305 and the second emptying switch valve 402 are opened, and the fourth replacement switch valve 304, the first emptying switch valve 401, the first cleaning switch valve 701, the first exhaust switch valve 91 and the third cleaning switch valve 703 are closed, and the nitrogen is sent into the vacuum tank 3 through the primary filter 21, and part of the replaced air is discharged through the second exhaust port, and part of the air is sent to the gas detector 82 through the air pump 81. The gas detector 82 is used to detect the combustible gas content and oxygen content in the vacuum tank 3 in real time until the replaced combustible gas content is lower than the first preset content and the oxygen content is lower than the second preset content, and the replacement of the air in the standby vacuum tank 3 is completed. After the cleaning of the ground tank 1 is completed and the oil and gas in the primary filter 21 are replaced, the oil and gas in the vacuum tank 3 are replaced. Specifically, open the nitrogen switch valve 201, the third replacement switch valve 303, the second cleaning switch valve 702 and the fifth replacement switch valve 305, and close the fourth replacement switch valve 304, the first emptying switch valve 401, the first cleaning switch valve 701, the first exhaust switch valve 91, the third cleaning switch valve 703 and the second emptying switch valve 402, and send the nitrogen into the vacuum tank 3 through the primary filter 21, and the displaced oil and gas are sent to the gas detector 82 through the air pump 81 until the displaced combustible gas content is lower than the first preset content and the oxygen content is lower than the second preset content, then the replacement of the oil and gas in the vacuum tank 3 is completed.

[0070] The gas outlet of the secondary filter 22 can be connected to the inlet of the air pump 81 through the sixth gas pipeline 106, the sixth gas pipeline 106 is provided with a sixth replacement switch valve 306, the secondary filter 22 is provided with a third exhaust port, and the third exhaust port is provided with a third exhaust switch valve 403. Before starting to clean the ground tank 1 and after replacing the air in the vacuum tank 3 with nitrogen, the air in the secondary filter 22 is replaced. Specifically, the nitrogen switch valve 201, the third replacement switch valve 303, the second cleaning switch valve 702, the third cleaning switch valve 703, the fourth cleaning switch valve 704, the sixth replacement switch valve 306 and the third emptying switch valve 403 are opened, and the fourth replacement switch valve 304, the first emptying switch valve 401, the first cleaning switch valve 701, the first exhaust switch valve 91, the fifth replacement switch valve 305, the second emptying switch valve 402, the fifth cleaning switch valve 705 and the sixth cleaning switch valve 706 are closed, and the nitrogen is sent to the secondary filter 22 through the primary filter 21, the vacuum tank 3, and the booster pump 4 in sequence, and part of the replaced air is discharged through the third exhaust port, and part of the air is sent to the gas detector 82 through the air pump 81. The gas detector 82 is used to detect the combustible gas content and the oxygen content in the secondary filter 22 in real time until the replaced combustible gas content is lower than the first preset content and the oxygen content is lower than the second preset content, then the replacement of the air in the secondary filter 22 is completed. After the cleaning of the ground tank 1 is completed and the oil and gas in the vacuum tank 3 are replaced, the oil and gas in the secondary filter 22 are replaced. Specifically, the nitrogen switch valve 201, the third replacement switch valve 303, the second cleaning switch valve 702, the third cleaning switch valve 703, the fourth cleaning switch valve 704 and the sixth replacement switch valve 306 are opened, and the fourth replacement switch valve 304, the first emptying switch valve 401, the first cleaning switch valve 701, the first exhaust switch valve 91, the fifth replacement switch valve 305, the second emptying switch valve 402, the fifth cleaning switch valve 705, the sixth cleaning switch valve 706 and the third emptying switch valve 403 are closed, and the nitrogen is sequentially sent to the secondary filter 22 through the primary filter 21, the vacuum tank 3, and the booster pump 4, and the replaced oil and gas are sent to the gas detector 82 through the air pump 81, until the replaced combustible gas content is lower than the first preset content and the oxygen content is lower than the second preset content, then the replacement of the oil and gas in the secondary filter 22 is completed.

[0071] The gas outlet of the spare secondary filter 23 can be connected to the inlet of the air pump 81 through the seventh gas pipeline 107, the seventh gas pipeline 107 is provided with a seventh replacement switch valve 307, the secondary filter 22 is provided with a fourth exhaust port, and the fourth exhaust port is provided with a fourth exhaust switch valve 404. Before starting to clean the ground tank 1 and after replacing the air in the vacuum tank 3 with nitrogen, the air in the spare secondary filter 23 is replaced. Specifically, the nitrogen switch valve 201, the third replacement switch valve 303, the second cleaning switch valve 702, the third cleaning switch valve 703, the sixth cleaning switch valve 706, the seventh replacement switch valve 307 and the fourth emptying switch valve 404 are opened, and the fourth replacement switch valve 304, the first emptying switch valve 401, the first cleaning switch valve 701, the first exhaust switch valve 91, the fifth replacement switch valve 305, the second emptying switch valve 402, the fourth cleaning switch valve 704 and the seventh cleaning switch valve 707 are closed, and the nitrogen is sent to the spare secondary filter 23 through the primary filter 21, the vacuum tank 3, and the booster pump 4 in sequence, and part of the replaced air is discharged through the fourth exhaust port, and part of the air is sent to the gas detector 82 through the air pump 81. The gas detector 82 is used to detect the combustible gas content and the oxygen content in the spare secondary filter 23 in real time until the replaced combustible gas content is lower than the first preset content and the oxygen content is lower than the second preset content, then the replacement of the air in the spare secondary filter 23 is completed. After the cleaning of the ground tank 1 is completed and the oil and gas in the vacuum tank 3 are replaced, the oil and gas in the spare secondary filter 23 are replaced. Specifically, the nitrogen switch valve 201, the third replacement switch valve 303, the second cleaning switch valve 702, the third cleaning switch valve 703, the sixth cleaning switch valve 706 and the seventh replacement switch valve 307 are opened, and the fourth replacement switch valve 304, the first emptying switch valve 401, the first cleaning switch valve 701, the first exhaust switch valve 91, the fifth replacement switch valve 305, the second emptying switch valve 402, the fourth cleaning switch valve 704, the seventh cleaning switch valve 707 and the fourth emptying switch valve 404 are closed, and the nitrogen is sequentially sent to the spare secondary filter 23 through the primary filter 21, the vacuum tank 3, and the booster pump 4, and the replaced oil and gas are sent to the gas detector 82 through the air pump 81, until the replaced combustible gas content is lower than the first preset content and the oxygen content is lower than the second preset content, then the replacement of the oil and gas in the spare secondary filter 23 is completed.

[0072] The gas outlet of the tertiary filter 24 is connected to the inlet of the air pump 81 through the eighth gas pipeline 108, the eighth gas pipeline 10 is provided with an eighth replacement switch valve 308, and the tertiary filter 24 is provided with a fifth exhaust port, and the fifth exhaust port is provided with a fifth exhaust switch valve 405. Before starting to clean the ground tank 1 and after replacing the air in the spare filter and / or the secondary filter 22 with nitrogen, the air in the tertiary filter 24 is replaced, taking the connection between the secondary filter 22 and the tertiary filter 24 as an example. Specifically, the nitrogen switch valve 201, the third replacement switch valve 303, the second cleaning switch valve 702, the third cleaning switch valve 703, the fourth cleaning switch valve 704, the fifth cleaning switch valve 705, the ninth cleaning switch valve 709, the eighth replacement switch valve 308 and the fifth emptying switch valve 405 are opened, and the fourth replacement switch valve 304, the first emptying switch valve 401, the first cleaning switch valve 701, the first exhaust switch valve 91, the fifth replacement switch valve 305, the second emptying switch valve 402, the sixth cleaning switch valve 706, and the seventh cleaning switch valve 707 are closed. , the eighth cleaning switch valve 708 and the tenth cleaning switch valve 710, the nitrogen is sent to the tertiary filter 24 through the primary filter 21, the vacuum tank 3, the booster pump 4, the secondary filter 22 in sequence, part of the replaced air is discharged through the fifth exhaust port, and part of the air is sent to the gas detector 82 through the air pump 81. The gas detector 82 is used to detect the combustible gas content and oxygen content in the standby tertiary filter 24 in real time until the replaced combustible gas content is lower than the first preset content and the oxygen content is lower than the second preset content, then the replacement of the air in the tertiary filter 24 is completed. After the cleaning of the ground tank 1 is completed and the oil and gas in the secondary filter 22 are replaced, the oil and gas in the tertiary filter 24 are replaced. Specifically, the nitrogen switch valve 201, the third replacement switch valve 303, the second cleaning switch valve 702, the third cleaning switch valve 703, the fourth cleaning switch valve 704, the fifth cleaning switch valve 705, the ninth cleaning switch valve 709 and the eighth replacement switch valve 308 are opened, and the fourth replacement switch valve 304, the first emptying switch valve 401, the first cleaning switch valve 701, the first exhaust switch valve 91, the fifth replacement switch valve 305, the second emptying switch valve 402, the sixth cleaning switch valve 706, the seventh cleaning switch valve 707, the eighth cleaning switch valve 708, the tenth cleaning switch valve 710 and the fifth emptying switch valve 405 are closed, and the nitrogen is sent to the tertiary filter 24 through the primary filter 21, the vacuum tank 3, the booster pump 4, and the secondary filter 22 in sequence, and the displaced oil and gas are sent to the gas detector 82 through the air pump 81, until the displaced combustible gas content is lower than the first preset content and the oxygen content is lower than the second preset content, then the replacement of the oil and gas in the tertiary filter 24 is completed.

[0073] Before cleaning the floor tank 1, when replacing the oil and gas in the floor tank 1, in order to replace the oil and gas in the connecting pipeline between the vacuum tank 3 and the floor tank 1, the present embodiment replaces the oil and gas in the floor tank 1 after replacing the air in the primary filter 21, the vacuum tank 3, and the secondary filter assembly. Before cleaning the floor tank 1 and after replacing the oil and gas in the secondary filter 22, the oil and gas in the floor tank 1 are replaced. Specifically, the nitrogen switch valve 201, the third replacement switch valve 303, the second cleaning switch valve 702, the third cleaning switch valve 703, the fourth cleaning switch valve 704, the fifth cleaning switch valve 705, the eighth cleaning switch valve 708 and the second replacement switch valve 302 are opened, and the fourth replacement switch valve 304, the first emptying switch valve 401, the first cleaning switch valve 701, the first exhaust switch valve 91, the fifth replacement switch valve 305, the second emptying switch valve 402, the sixth cleaning switch valve 706, the seventh cleaning switch valve 707, the sixth replacement switch valve 306, the third emptying switch valve 403, the ninth cleaning switch valve 709 and the tenth cleaning switch valve 710 are closed, and the nitrogen is sent into the ground tank 1 through the primary filter 21, the vacuum tank 3, the booster pump 4, and the secondary filter 22 in sequence, and the displaced oil and gas are sent to the gas detector 82 through the air pump 81, until the displaced combustible gas content is lower than the first preset content and the oxygen content is lower than the second preset content, then the replacement of the oil and gas in the ground tank 1 is completed. In other embodiments, after the air in one of the secondary filter 22 and the spare secondary filter 23 in the secondary filter assembly is replaced, the oil and gas in the ground tank 1 may be replaced.

[0074] Furthermore, before the floor tank 1 is cleaned, the amount of oil in the floor tank 1 may exceed the amount of oil required for cleaning, therefore, the present embodiment adds a temporary oil storage tank 5 and a first oil amount detection unit, the first oil amount detection unit is used to detect the amount of oil in the floor tank 1, and the temporary oil storage tank 5 can be selectively connected to the protective gas delivery device or the vacuum pump 90. The first oil amount detection unit can adopt the existing oil amount detection unit in the floor tank 1, such as a liquid level sensor.

[0075] The air inlet of the vacuum pump 90 can be connected to the first air outlet of the temporary oil storage tank 5, and a second exhaust switching valve 92 is provided on the connecting pipeline between the air inlet of the vacuum pump 90 and the first air outlet of the temporary oil storage tank 5; the oil inlet and outlet of the temporary oil storage tank 5 are connected to the oil inlet and outlet of the ground tank 1 through the first oil circuit 501, and a first switching valve 504 is provided on the first oil circuit 501.

[0076] Before cleaning the floor tank 1, if the first oil level detection unit detects that the liquid level in the floor tank 1 exceeds the second preset liquid level, the first switch valve 504 and the second exhaust switch valve 92 can be opened, and the first exhaust switch valve 91 can be closed, and a portion of the oil in the floor tank 1 can be sent to the temporary oil storage tank 5 for temporary storage using the vacuum pump 90 until the liquid level in the floor tank 1 reaches the second preset liquid level.

[0077] The oil inlet and outlet of the temporary oil storage tank 5 can be connected to the oil inlet of the tertiary filter 24 through the oil circuit where the second oil circuit 502 is located, and a second switch valve 505 is provided on the second oil circuit 502; the oil outlet of the tertiary filter 24 can be connected to the first oil circuit 501 through the oil circuit where the third oil circuit 503 is located, and a third switch valve 506 is provided on the third oil circuit 503; the air inlet of the temporary oil storage tank 5 can be connected to the main gas pipeline 100 through the ninth gas pipeline 109, and a ninth replacement switch valve 309 is provided on the ninth gas pipeline 109.

[0078] When the oil in the temporary oil storage tank 5 needs to be sent back to the ground tank 1 after cleaning the ground tank 1, the oil in the temporary oil storage tank 5 needs to be filtered through the three-stage filter 24, and then the filtered oil is sent back to the ground tank 1. Specifically, the first switch valve 504 and the ninth replacement switch valve 309 are opened, the second switch valve 505, the first emptying switch valve 401 and the second exhaust switch valve 92 are closed, and nitrogen is sent into the temporary oil storage tank 5 to increase the pressure in the temporary oil storage tank 5, so that the oil in the temporary oil storage tank 5 directly enters the ground tank 1 through the first oil path 501.

[0079] The temporary oil storage tank 5 solves the problem that the oil level in the ground tank 1 is too high, which makes it impossible to clean the ground tank 1 in time. The temporary oil storage tank 5 is connected to the oil inlet of the gas station through a pipeline, so that the gas station can sell oil normally, thereby reducing the economic losses caused to the gas station.

[0080] Further, the gas outlet of the temporary oil storage tank 5 can be connected to the inlet of the air pump 81 through the tenth gas pipeline 110, and the tenth replacement switch valve 310 is provided on the tenth gas pipeline 110; the temporary oil storage tank 5 is provided with a sixth exhaust port, and the sixth exhaust port is provided with a sixth exhaust switch valve 406. Before cleaning the ground tank 1, the air in the temporary oil storage tank 5 is replaced with nitrogen. Specifically, the nitrogen switch valve 201, the ninth replacement switch valve 309, the tenth replacement switch valve 310 and the sixth exhaust switch valve 406 are opened, and the second exhaust switch valve 92, the first switch valve 504 and the second switch valve 505 are closed. The air in the temporary oil storage tank 5 is replaced with nitrogen, and part of the replaced air is discharged through the sixth exhaust port, and part of the air is sent to the gas detector 82 through the air pump 81. The gas detector 82 is used to detect the combustible gas content and oxygen content in the temporary oil storage tank 5 in real time. After the cleaning of the ground tank 1 is completed, the oil and gas in the temporary oil storage tank 5 are replaced with nitrogen. Specifically, open the nitrogen switch valve 201, the ninth replacement switch valve 309 and the tenth replacement switch valve 310, close the first switch valve 504, the second switch valve 505, the third switch valve 506, the second exhaust switch valve 92 and the sixth emptying switch valve 406, and use nitrogen to replace the oil and gas in the temporary oil storage tank 5 until the replaced combustible gas content is lower than the first preset content and the oxygen content is lower than the second preset content, thereby completing the replacement of the oil and gas in the temporary oil storage tank 5.

[0081] Furthermore, the temporary oil storage tank 5 can also be connected to the oil inlet of the gas station through a refueling pipeline, and the refueling pipeline is provided with a refueling switch valve 802. During the cleaning of the ground tank 1, the temporary oil storage tank 5 can be used to supply oil to the gas station to avoid affecting the operation of the gas station.

[0082] Furthermore, the above-mentioned oil tank cleaning system also includes an oil-gas separation device 6, the inlet of the oil-gas separation device 6 is connected to the outlet of the gas detector 82 through the eleventh gas pipeline 111, the eleventh gas pipeline 111 is provided with a first separation switch valve 601, and the outlet of the oil-gas separation device 6 is connected to the ground tank 1 through the return oil line, and the oil products in the oil gas are separated by the oil-gas separation device 6, and the separated oil products are sent back to the ground tank 1.

[0083] The gas outlet of the vacuum pump 90 is connected to the inlet of the oil-gas separation device 6 through the twelfth gas pipeline 112, and the second separation switch valve 602 is provided on the twelfth gas pipeline 112. The eleventh gas pipeline 111 is connected to the inlet of the oil-gas separation device 6 through the twelfth gas pipeline 112. When the vacuum pump 90 is working, the gas extracted by the vacuum pump 90 is sent to the oil-gas separation device 6.

[0084] Specifically, the oil-gas separation device 6 includes a condenser and an adsorber, wherein the condenser has an oil-gas channel and a medium channel, the medium channel is a part of the liquid nitrogen delivery pipeline, the first liquid nitrogen switch valve 200 is arranged at the inlet of the medium channel, the outlet of the medium channel is provided with d1, the inlet end of the oil-gas channel is connected to the twelfth gas pipeline 112, the outlet end of the oil-gas channel is connected to the inlet end of the adsorber, the outlet end of the adsorber is connected to the ground tank 1 through the oil return oil line, the adsorber is provided with a seventh drain port, and the seventh drain port is provided with a seventh drain switch valve. Preferably, the medium channel is located upstream of the heat exchanger 72.

[0085] The oil and gas in the oil and gas channel are condensed by the liquid nitrogen in the medium channel, so that the gaseous oil in the oil and gas is condensed to form liquid oil, and the liquid nitrogen is heated at the same time, so as to separate the gaseous oil from nitrogen, oxygen and other gases in the oil and gas; the separated gas is then sent to the adsorber to separate the gaseous oil that has not been separated therein by adsorption, and the seventh exhaust switch valve is opened so that the gas separated by the adsorber can be directly discharged into the atmosphere through the seventh open air port, and can also be used for other purposes.

[0086] In this embodiment, a temperature sensor is provided at the outlet of the medium channel. During the oil-gas separation process using the oil-gas separation device 6, if the temperature at the outlet of the medium channel exceeds the preset temperature, it means that the flow rate of liquid nitrogen needs to be increased to meet the energy demand for condensing the oil and gas.

[0087] Furthermore, before cleaning the ground tank 1, when nitrogen is used to replace the air in the primary filter 21, the vacuum tank 3, the secondary filter assembly, the tertiary filter 24 and the temporary oil storage tank 5, the seventh drain switch valve and the second separation switch valve 602 are opened, the oil return valve 603 is closed, and the displaced air is directly discharged through the seventh drain port. When nitrogen is used to replace the oil and gas in the ground tank 1 and when nitrogen is used to replace the oil and gas in the primary filter 21, the vacuum tank 3, the secondary filter assembly, the tertiary filter 24 and the temporary oil storage tank 5 after cleaning the ground tank 1, the seventh drain switch valve, the second separation switch valve 602 and the oil return valve 603 are closed, the displaced oil and gas are separated by the oil-gas separation device 6, the separated oil and gas are sent back to the ground tank 1, and the separated air is discharged through the seventh drain port.

[0088] Furthermore, in order to facilitate the slag discharge of the vacuum tank 3, a slag discharge port is provided at the bottom of the vacuum tank 3, and a slag discharge valve 801 is provided at the slag discharge port. Preferably, the slag discharge valve 801 is a manual valve.

[0089] Furthermore, during the cleaning process of the ground tank, due to the contact and friction between the oil product itself or the oil product and other objects, static charges will be rapidly generated, forming an accumulation of static electricity of like charges, and forming a potential difference with a charged object at a close distance. When the accumulated static charge reaches a certain level, it will discharge with a charged metal conductor at a close distance or a non-conductor with a thickness of less than 8mm. At this time, if the content of the oil, gas and air mixture is within the explosion limit, it will cause explosion and combustion. For this reason, the present embodiment also adds a grounding column. Specifically, the cleaning nozzle, vacuum tank 3, temporary oil storage tank 5, the motor driving the vacuum pump 90 and the booster pump 4, and all the sensors used are connected to the grounding column through a ground wire, and then the grounding column is connected to the grounding pile of the ground tank 1 of the gas station, and the grounding is measured by a grounding megohmmeter to measure whether the grounding is qualified. When the grounding is confirmed to be qualified, the above-mentioned oil and gas cleaning system starts to work.

[0090] like Figure 2 As shown, the present embodiment also provides an oil tank cleaning method, which uses the above-mentioned oil and gas cleaning system, including the following steps: using a vacuum pump 90 to extract the oil in the ground tank 1 and send it into the vacuum tank 3 after filtering, using a booster pump 4 to pressurize the oil in the vacuum tank 3 and send the pressurized oil to the cleaning nozzle, and using the lifting and 360° rotation of the cleaning nozzle to perform high-pressure flushing on the inner wall of the ground tank 1.

[0091] The specific steps include:

[0092] S1. Use nitrogen to replace the air in the temporary oil storage tank 5, and use nitrogen to replace the air in the primary filter 21, vacuum tank 3, secondary filter assembly, and tertiary filter 24 in sequence. After completing the air replacement in the secondary filter assembly, use nitrogen to replace the oil and gas in the tank 1.

[0093] S2, detecting whether the liquid level in the ground tank 1 exceeds the second preset liquid level. If so, pumping the oil in the ground tank 1 to the temporary oil storage tank 5 for temporary storage until the liquid level in the ground tank 1 reaches the second preset liquid level; if not, executing S3.

[0094] S3, pumping the oil in the ground tank 1 into the vacuum tank 3 until the liquid level in the vacuum tank 3 is not lower than the first preset liquid level, and then the booster pump 4 starts to clean the ground tank 1 for a preset time.

[0095] It should be noted that the amount of oil corresponding to the liquid level in the vacuum tank 3 reaching the first preset liquid level is smaller than the amount of oil corresponding to the liquid level in the ground tank 1 reaching the second preset liquid level.

[0096] The above preset time is a time set according to actual needs, such as 5 minutes, and is not specifically limited here.

[0097] During the cleaning process of the floor tank 1, in order to ensure that there is sufficient oil in the vacuum tank 3 for cleaning the floor tank 1, if the liquid level in the vacuum tank 3 is lower than the third preset liquid level, the vacuum pump 90 is started while the floor tank 1 is being cleaned to deliver the oil in the floor tank 1 to the vacuum tank 3 until the liquid level in the vacuum tank 3 reaches the first preset liquid level. It is worth noting that the first preset liquid level is greater than the third preset liquid level.

[0098] During the cleaning process of the ground tank 1, the air pump 81 is kept working, and the gas detector 82 is used to detect the combustible gas content and the oxygen content in the ground tank 1. If the combustible gas content is not lower than the first preset content and / or the oxygen content is not lower than the second preset content, the heat exchange device is operated to replace the oil and gas in the ground tank 1 with nitrogen to improve the safety of the ground tank 1 during the cleaning process.

[0099] S4. When the preset time is completed, take a sample from the ground tank 1, use the oil quality detector to detect the quality of the sample and determine whether it is qualified. If it is unqualified, return to the above step S3 until the oil quality in the ground tank 1 is qualified; if it is qualified, execute S5.

[0100] S5. Filter the oil in the temporary oil storage tank 5 and the vacuum tank 3 through the three-stage filter 24, and send the filtered oil back to the ground tank 1.

[0101] S6. Use nitrogen to replace the oil and gas in the temporary oil storage tank 5, and use nitrogen to replace the oil and gas in the primary filter 21, vacuum tank 3, secondary filter assembly, and tertiary filter 24 in turn. After completing the air replacement in the secondary filter assembly, use nitrogen to replace the oil and gas in the ground tank 1.

[0102] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the embodiments here. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the claims of the present invention.

[0103] In the description of the present invention, it should be noted that the terms "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance. Among them, the terms "first position" and "second position" are two different positions.

[0104] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

Claims

1. An oil tank cleaning system, characterized in that: include: A suction device, comprising a vacuum pump (90), a vacuum tank (3) and a primary filter (21); the oil tank, the primary filter (21), the vacuum tank (3) and the vacuum pump (90) are sequentially connected; the vacuum pump (90) is used to extract the oil in the oil tank and filter it through the primary filter (21) before temporarily storing it in the vacuum tank (3); A cleaning device, comprising a booster pump (4) and a cleaning nozzle, the vacuum tank (3), the booster pump (4) and the cleaning nozzle being connected in sequence, the cleaning nozzle being insertable into the oil tank and being able to be raised and lowered relative to the oil tank and rotated 360 degrees to spray and clean the inner wall of the oil tank; a protective gas delivery device, used to replace the oil and gas in the oil tank, as well as the air or oil and gas in the vacuum tank (3) and the primary filter (21) with the protective gas; A gas detector (82) for detecting the combustible gas content and oxygen content in the oil tank, the vacuum tank (3), and the primary filter (21); A secondary filter assembly, the secondary filter assembly comprising a secondary filter (22) and a spare secondary filter (23), wherein pressure sensors are provided at the oil inlet of the spare secondary filter (23) and the oil inlet of the secondary filter (22); A second oil level detection unit is provided in the vacuum tank (3), and the second oil level detection unit adopts a liquid level sensor; A grounding column is provided, wherein the cleaning nozzle, the vacuum tank (3), the temporary oil storage tank (5), the motor driving the vacuum pump (90) and the booster pump (4), and all sensors used are connected to the grounding column via a ground wire, and the grounding column is then connected to the grounding pile of the ground tank (1) of the gas station, and a grounding megohmmeter is used to measure whether the grounding is qualified.

2. The oil tank cleaning system according to claim 1, characterized in that: It also includes an oil-gas separation device (6) capable of being communicated with the oil tank, the vacuum tank (3) and the primary filter (21), for separating the oil and gas displaced by the oil tank, the vacuum tank (3) and the primary filter (21), and returning the separated oil to the oil tank.

3. The oil tank cleaning system according to claim 1, characterized in that: The booster pump (4) can be connected to the cleaning nozzle via the secondary filter assembly.

4. The oil tank cleaning system according to claim 3, characterized in that: It also includes a three-stage filter (24), and the two-stage filter component can be directly connected to the cleaning nozzle, or can be connected to the cleaning nozzle through the three-stage filter (24).

5. The oil tank cleaning system according to claim 4, characterized in that: Also includes: A first oil level detection unit, used to detect the oil level in the oil tank; A temporary oil storage tank (5), wherein the temporary oil storage tank (5) can be connected to the oil tank, and can also be selectively connected to the protective gas delivery device or the vacuum pump (90).

6. The oil tank cleaning system according to claim 5, characterized in that: The temporary oil storage tank (5) can also be connected to the oil tank via the third-stage filter (24).

7. The oil tank cleaning system according to claim 5, characterized in that: It also includes an oil quality detector for detecting the quality of the oil in the temporary oil storage tank (5) and / or the vacuum tank (3).

8. The oil tank cleaning system according to claim 5, characterized in that: The temporary oil storage tank (5) can be connected to the oil inlet of the fuel dispenser via a fueling pipeline, and a fueling switch valve (802) is provided on the fueling pipeline.

9. A method for cleaning an oil tank, characterized in that: The oil tank cleaning system according to any one of claims 1 to 8 is used, wherein the oil in the oil tank is extracted by a vacuum pump (90) and sent to a vacuum tank (3) after filtering, and the oil in the vacuum tank (3) is pressurized by a booster pump (4) and the pressurized oil is sent to a cleaning nozzle, and the inner wall of the oil tank is high-pressure washed by lifting and rotating the cleaning nozzle 360 ​​degrees.

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