A mechanical cleaning system and device for double vertical pipe floating roof storage tank

Abstract

The present invention relates to a dual vertical pipe floating roof tank mechanical cleaning system and device, including an oil suction system, an oil transfer system, a dual vertical pipe cleaning system, a tank top cleaning machine injection system, a hot water circulation cleaning system and an inert gas replacement system, wherein interlocking control is implemented between the various systems to ensure construction safety and efficiency. The present invention adopts a new dual vertical pipe mechanical cleaning, which can greatly improve the operating efficiency while ensuring safety, thereby realizing safe, intelligent and efficient cleaning of large floating roof tanks.

Description

Technical Field

[0001] The invention relates to the technical field of tank cleaning, and in particular to a mechanical cleaning system and device for a double vertical pipe floating roof tank. Background Art

[0002] In recent years, with the rapid development of petrochemical industry, new requirements have been continuously put forward for the safety management of oil storage and transportation. The safe operation and management of oil storage and transportation are inseparable from the tank cleaning industry. Among them, the cleaning of large floating roof tanks is the most complicated and time-consuming. For example, using existing mechanical cleaning equipment to clean a 100,000 cubic meter crude oil floating roof tank, the entire construction period takes at least 2 months, which is extremely time-consuming and labor-intensive.

[0003] Floating roof tanks are usually used to store crude oil. After a period of use, the solid impurities and heavy components contained in the crude oil continue to accumulate, and the sludge at the bottom of the tank gradually increases, which is bound to affect the quality of the oil. If the tank is not cleaned regularly, it will seriously affect the quality of the oil stored in the tank, reduce the effective volume of the tank, and reduce the heating efficiency of the tank, resulting in energy waste. In addition, when the oil tank is converted to store another type of oil or when the oil tank leaks or is otherwise damaged and needs to be emptied for inspection or hot work repair, it must also be cleaned. For the cleaning of crude oil tanks, the existing technologies mainly include the following.

[0004] 1. Manual tank cleaning method

[0005] Manual tank cleaning is a method of cleaning oil tanks that is still used in some places. Most of them are small oil storage tanks, such as tanks below 1,000 cubic meters. The manual tank cleaning method must use a full set of explosion-proof equipment and tools, and the operators must be equipped with professional protective equipment. The tanks must be forced to ventilate during the entire operation, and the gas composition in the tank must be monitored in real time. The workload is large and the working environment is poor. Although the state, industry and enterprises have formulated various safety operation standards for the safety of manual tank cleaning, accidents still occur frequently. At the same time, the manual cleaning method also has the disadvantages of incomplete cleaning and long suspension of the cleaned tanks. It does not meet the current requirements of safety, energy saving and environmental protection, and is now being replaced by mechanical cleaning methods.

[0006] 2. Crushing and dissolving mechanical cleaning method

[0007] This method is represented by the COW technology of Japan Taiho. Its basic theory is to use the principle of jetting to eject the light components in the tank through the automatically rotating jet cleaning machine inserted into the tank, forming a jet in the tank, so that the sediment in the tank is suspended and diffused, and fully mixed with the light components, thereby realizing the restoration of sediments with poor fluidity or even loss of fluidity into a flowable dispersed phase or mixed oil, and then transferring these restored oil products out, thereby achieving the purpose of reasonable recovery. This process is currently the most widely used process in China, with the purpose of oil recovery, but due to the small number of jet cleaning machines driven by the device at a time (only 1-2 units), the overall operation time of the cleaning machine is long, and the on-site cleaning operation time is too long.

[0008] 3. Large flow disturbance mechanical cleaning method

[0009] This method is represented by the American McWang technology. Its basic theory is to use the disturbance principle to form a strong fluid disturbance in the tank through the jets of 2-3 large-flow cleaning guns. Under the action of the disturbance, the sediment at the bottom of the tank is constantly mixed with the light components, thereby achieving the purpose of eliminating the sediment. When using this process, there needs to be a large amount of flowable oil in the tank, usually keeping the floating roof in a floating state, there is no gas phase space in the tank, and there is no need to inject nitrogen into the tank. It is highly safe, but due to the poor properties of domestic oil products, it cannot be guaranteed that the heavy components in all areas of the tank will flow during the oil rotation and mixing process, so the cleaning effect is usually poor. Summary of the invention

[0010] The technical problem to be solved by the present invention is to provide a double vertical pipe floating roof storage tank mechanical cleaning system and device, which adopts a new double vertical pipe mechanical cleaning, which can greatly improve the operating efficiency while ensuring safety, thereby realizing safe, intelligent and efficient cleaning of large floating roof storage tanks.

[0011] The technical solution adopted by the present invention to solve the technical problem is: to provide a double vertical pipe floating roof tank mechanical cleaning system and device, including a vacuum suction device, a storage tank to be cleaned, an oil receiving storage tank and an oil-water separator, the oil receiving storage tank is respectively provided with a suction pipeline, a first vertical pipe and a second vertical pipe, the oil receiving storage tank is arranged with a tank top cleaning machine spray system connected to the first vertical pipe and the second vertical pipe, one end of the suction pipeline is connected to the vacuum suction device, and the vacuum suction device is arranged with a transfer pipeline, a first cleaning pipeline and a second cleaning pipeline in parallel;

[0012] One end of the first cleaning pipeline is connected to the first vertical pipe, and one end of the second cleaning pipeline is connected to the second vertical pipe. A first connecting pipeline is arranged between one end of the first cleaning pipeline and one end of the second cleaning pipeline, and a first switch valve is arranged on the first connecting pipeline. A second switch valve, a first cleaning pump, a third switch valve and a first check valve are arranged in sequence on the first cleaning pipeline from the vacuum suction device to the first vertical pipe. A fourth switch valve, a second cleaning pump, a fifth switch valve and a second check valve are arranged in sequence on the second cleaning pipeline from the vacuum suction device to the second vertical pipe. A second connecting pipeline is arranged between the first cleaning pipeline and the second cleaning pipeline. The connection point of one end of the second connecting pipeline is located between the second switch valve and the first cleaning pump, and the connection point of the other end of the second connecting pipeline is located between the fourth switch valve and the second cleaning pump. A sixth switch valve is arranged on the second connecting pipeline.

[0013] One end of the transfer pipeline is bifurcated into three branch pipelines, one branch pipeline is connected to one end of the second cleaning pipeline, one branch pipeline is connected to the oil receiving storage tank, and the other branch pipeline is connected to the oil-water separator. A seventh switch valve is installed on each branch pipeline. An oil discharge pump, a third one-way valve and a fourth one-way valve are sequentially arranged on the transfer pipeline from the vacuum suction device to the three branch pipelines. A third connecting pipeline is arranged between the second cleaning pipeline and the transfer pipeline. An eighth switch valve is installed on the third connecting pipeline. The connection point of one end of the third connecting pipeline is located between the third one-way valve and the fourth one-way valve, and the connection point of the other end of the third connecting pipeline is located between the fourth switch valve and the second cleaning pump. A fourth connecting pipeline is connected to the oil-water separator, one end of the fourth connecting pipeline is connected to the first cleaning pipeline, and the connection point of one end of the fourth connecting pipeline is located between the second switch valve and the first cleaning pump. A ninth switch valve is installed on the fourth connecting pipeline.

[0014] As a supplement to the technical solution described in the present invention, a tenth switch valve is provided on the suction pipeline between the oil discharge pump and the vacuum suction device and between the oil discharge pump and the third one-way valve.

[0015] As a supplement to the technical solution described in the present invention, two filters are arranged in parallel between the vacuum suction device and the suction pipeline.

[0016] As a supplement to the technical solution described in the present invention, two eleventh switch valves are provided on each parallel pipeline between the vacuum suction device and the suction pipeline, and the two eleventh switch valves are respectively located on both sides of the corresponding filter.

[0017] As a supplement to the technical solution described in the present invention, a twelfth switch valve is arranged on the suction pipeline.

[0018] As a supplement to the technical solution described in the present invention, the vacuum suction device includes a vacuum pump, a vacuum tank and auxiliary equipment. The vacuum pump is connected to the vacuum tank. The gas in the vacuum tank is extracted through the vacuum pump's suction action, so that negative pressure is generated in the vacuum tank. As long as the inlet and outlet valves of the filter are opened, the oil in the cleaned storage tank can automatically enter the vacuum tank through the suction pipeline, thereby realizing the automatic suction function of the oil in the cleaned tank.

[0019] As a supplement to the technical solution described in the present invention, an inert gas replacement system is also included. The inert gas replacement system includes a monitoring device installed in the cleaned storage tank and an injection device for injecting inert gas into the cleaning storage tank. The monitoring device monitors the oxygen concentration in the cleaned storage tank in real time. Only when the oxygen concentration in the tank is lower than 8% VOL can the cleaning machine be turned on for mechanical cleaning. The oxygen concentration data in the tank is interlocked with the entire system. Once the oxygen concentration in the tank exceeds the standard, the system will automatically stop the operation of the cleaning pump while issuing an alarm, fully ensuring the safety of the operation.

[0020] As a supplement to the technical solution described in the present invention, the tank top cleaning machine spray system includes a cleaning machine temporarily installed on the top of the tank to be cleaned, a cleaning loop line and a cleaning machine branch line. The cleaning loop line is respectively connected to the first vertical pipe and the second vertical pipe. A plurality of cleaning machine branches are evenly distributed on the cleaning loop line, and a cleaning machine is installed at the end of each cleaning machine branch line.

[0021] As a supplement to the technical solution described in the present invention, the diameter of the cleaning loop line is larger than the diameter of the cleaning machine branch line.

[0022] As a supplement to the technical solution described in the present invention, a thirteenth switch valve is arranged on the first vertical pipe, and a fourteenth switch valve is arranged on the second vertical pipe.

[0023] Beneficial effects: The present invention relates to a mechanical cleaning system and device for a double vertical pipe floating roof storage tank, which has the following advantages:

[0024] 1. Through the double vertical pipe system, in coordination with the different operating states of the two cleaning pumps, it is possible to realize the process of multiple cleaning machines on the tank top running simultaneously, greatly improving the cleaning efficiency;

[0025] 2. In order to minimize the on-site electricity consumption and meet the requirements of different working conditions, two cleaning pumps and one oil discharge pump are arranged on a cleaning skid in the present invention. The cleaning pump has the characteristics of high head and low flow, and the oil discharge pump has the characteristics of low head and high flow. Through the switching of pipelines and valves between the three pumps, the three pumps can be connected in series, in parallel, used independently, one in operation and one in standby, etc., so that different construction can be adopted according to different on-site working conditions and different properties of the oil products in the tank to be cleaned, which can not only improve efficiency but also reduce energy consumption;

[0026] 3. The tank top cleaning machine can be operated in different areas. Through the double vertical pipe system, the tank top cleaning loop and the corresponding valve switches, each vertical pipe can independently supply the cleaning medium required for the cleaning machine in its respective area, or only one vertical pipe can be used to supply the cleaning medium required for all cleaning machines.

[0027] 4. On the basis of ensuring safety, it can greatly improve the operating efficiency, thereby realizing safe, intelligent and efficient cleaning of large floating roof storage tanks. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a schematic diagram of the structure of the present invention;

[0029] Figure 2 It is a structural schematic diagram of the double vertical pipe cleaning system of the present invention;

[0030] Figure 3 It is a structural schematic diagram of the hot water circulation cleaning system of the present invention;

[0031] Figure 4 It is a structural schematic diagram of the oil product transfer system of the present invention;

[0032] Figure 5 It is a structural schematic diagram of the spray system of the tank top cleaning machine of the present invention;

[0033] Figure 6 It is a structural schematic diagram of the oil suction system described in the present invention.

[0034] Diagram: 1. Oil suction system, 2. Oil transfer system, 3. Double vertical pipe cleaning system, 4. Hot water circulation cleaning system, 5. Vacuum suction device, 6. Filter, 7. Suction pipeline, 8. Cleaned storage tank, 9. Oil discharge pump, 10. Transfer pipeline, 11. Oil receiving tank, 12. First cleaning pump, 13. Second cleaning pump, 14. Oil-water separator, 15. First vertical pipe, 16. Second vertical pipe, 17. Cleaning loop, 18. Cleaning machine branch line, 19. Cleaning machine, 20. First cleaning pipeline, 21. Second cleaning pipeline, 22. Second switch valve, 23. Third switch valve Close valve, 24, fourth switch valve, 25, fifth switch valve, 26, first non-return valve, 27, first switch valve, 28, second non-return valve, 29, first connecting pipeline, 30, second connecting pipeline, 31, sixth switch valve, 32, third connecting pipeline, 33, eighth switch valve, 34, branch pipeline, 35, fourth connecting pipeline, 36, ninth switch valve, 37, third non-return valve, 38, fourth non-return valve, 39, tenth switch valve, 40, seventh switch valve, 41, eleventh switch valve, 42, twelfth switch valve, 43, thirteenth switch valve, 44, fourteenth switch valve. DETAILED DESCRIPTION

[0035] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms fall within the scope limited by the appended claims of the application equally.

[0036] The embodiment of the present invention relates to a mechanical cleaning system and device for a double vertical pipe floating roof storage tank, such as Figure 1 As shown, it includes a vacuum suction device 5, a storage tank to be cleaned 8, an oil receiving storage tank 11 and an oil-water separator 14. The oil receiving storage tank 11 is respectively provided with a suction pipeline 7, a first vertical pipe 15 and a second vertical pipe 16. The oil receiving storage tank 11 is provided with a tank top cleaning machine spray system connected to the first vertical pipe 15 and the second vertical pipe 16. One end of the suction pipeline 7 is connected to the vacuum suction device 5. The vacuum suction device 5 is provided with a transfer pipeline 10, a first cleaning pipeline 20 and a second cleaning pipeline 21 in parallel.

[0037] One end of the first cleaning pipeline 20 is connected to the first vertical pipe 15, and one end of the second cleaning pipeline 21 is connected to the second vertical pipe 16. A first connecting pipeline 29 is provided between one end of the first cleaning pipeline 20 and one end of the second cleaning pipeline 21. A first switch valve 27 is provided on the first connecting pipeline 29. A second switch valve 22, a first cleaning pump 12, a third switch valve 23 and a first check valve 26 are sequentially provided on the first cleaning pipeline 20 from the vacuum suction device 5 to the first vertical pipe 15. The second cleaning pipeline 2 1, a fourth switch valve 24, a second cleaning pump 13, a fifth switch valve 25 and a second one-way valve 28 are sequentially arranged from the vacuum suction device 5 to the second vertical pipe 16, a second connecting pipeline 30 is arranged between the first cleaning pipeline 20 and the second cleaning pipeline 21, a connection point of one end of the second connecting pipeline 30 is located between the second switch valve 22 and the first cleaning pump 12, and a connection point of the other end of the second connecting pipeline 30 is located between the fourth switch valve 24 and the second cleaning pump 13, and a sixth switch valve 31 is arranged on the second connecting pipeline 30;

[0038] One end of the transfer pipeline 10 is bifurcated into three branch pipelines 34, one branch pipeline 34 is connected to one end of the second cleaning pipeline 21, one branch pipeline 34 is connected to the oil receiving storage tank 11, and another branch pipeline 34 is connected to the oil-water separator 14. Each branch pipeline 34 is installed with a seventh switch valve 40. The transfer pipeline 10 is provided with an oil discharge pump 9, a third check valve 37 and a fourth check valve 38 in sequence from the vacuum suction device 5 to the three branch pipelines 34. A third connecting pipeline 32 is provided between the second cleaning pipeline 21 and the transfer pipeline 10. An eighth switch valve 33 is installed on the third connecting pipeline 32, and the connection at one end of the third connecting pipeline 32 is located between the third one-way valve 37 and the fourth one-way valve 38, and the connection at the other end of the third connecting pipeline 32 is located between the fourth switch valve 24 and the second cleaning pump 13. The oil-water separator 14 is connected to the fourth connecting pipeline 35, and one end of the fourth connecting pipeline 35 is connected to the first cleaning pipeline 20. The connection at one end of the fourth connecting pipeline 35 is located between the second switch valve 22 and the first cleaning pump 12, and a ninth switch valve 36 is installed on the fourth connecting pipeline 35.

[0039] A tenth switch valve 39 is provided on the suction pipeline 7 between the oil discharge pump 9 and the vacuum suction device 5 and between the oil discharge pump 9 and the third one-way valve 37 .

[0040] The first vertical pipe 15 is provided with a thirteenth switch valve 43 , and the second vertical pipe 16 is provided with a fourteenth switch valve 44 .

[0041] The oil suction system 1, oil transfer system 2, double vertical pipe cleaning system 3, tank top cleaning machine injection system, hot water circulation cleaning system 4 and inert gas replacement system are interlocked and controlled to ensure construction safety and efficiency.

[0042] like Figure 6 As shown, the oil product suction system 1 includes two filters 6, a set of vacuum suction devices 5, a storage tank to be cleaned 8 and a suction pipeline 7 temporarily installed at the operation site. The vacuum suction device 5 includes a vacuum pump, a vacuum tank and auxiliary equipment. The vacuum pump is connected to the vacuum tank. The gas in the vacuum tank is extracted by the vacuum pump to generate negative pressure in the vacuum tank. As long as the inlet and outlet valves of the filter 6 (i.e., four eleventh switch valves 41) are opened, the oil in the storage tank 8 to be cleaned can automatically enter the vacuum tank through the suction pipeline 7, thereby realizing the automatic suction function of the oil in the tank 8 to be cleaned. The suction pipeline 7 is provided with a twelfth switch valve 42, which is always open under normal circumstances.

[0043] like Figure 4 As shown, the oil transfer system 2 includes a vacuum suction device 5, an oil discharge pump 9, a third one-way valve 37 and a fourth one-way valve 38, an oil receiving storage tank 11, and a transfer pipeline 10 temporarily installed at the work site. Considering that the oil does not need to be lifted to a large height during oil transfer, but the oil transfer speed needs to be guaranteed, in line with the purpose of energy saving and in order to minimize the electricity consumption at the construction site, the oil discharge pump 9 adopts a low-lift, high-flow centrifugal pump. Installing a one-way valve on the transfer pipeline 10 can avoid the phenomenon of oil backflow in the oil receiving storage tank 11.

[0044] like Figure 2 As shown, the double vertical pipe cleaning system 3 includes a vacuum suction device 5, a first cleaning pump 12, a second cleaning pump 13, a first vertical pipe 15 and a second vertical pipe 16, and corresponding pipeline valves for series-parallel conversion temporarily installed at the work site.

[0045] Considering that each cleaning machine has its limit flow value when spraying, in line with the purpose of energy saving, in order to minimize the electricity consumption on the construction site, the two cleaning pumps use high-lift, low-flow centrifugal pumps, but their flow is not less than the limit flow value of a single cleaning machine when spraying. According to the viscosity of the oil in the 8 tanks to be cleaned, through the pipeline switching function, the two cleaning pumps can be used in parallel, can be used independently at the same time, or can realize the operation mode of one in use and one in standby.

[0046] If the fluidity of the oil in the cleaned storage tank 8 is relatively good and the oil suction capacity is good, the second switch valve 22, the third switch valve 23, the fourth switch valve 24, the fifth switch valve 25, the thirteenth switch valve 43, and the fourteenth switch valve 44 can be opened, and the first switch valve 27 can be closed at the same time. At this time, the first cleaning pump 12, the second cleaning pump 13, the first vertical pipe 15 and the second vertical pipe 16 are used in a one-to-one correspondence, thereby realizing the process in which multiple cleaning machines on the tank top can be operated simultaneously, greatly improving the cleaning efficiency. If the oil in the cleaned tank is relatively viscous and the oil suction speed cannot meet the simultaneous operation of two cleaning pumps, only one cleaning pump can be operated at this time, and the other cleaning pump can be used as a backup. In this way, different process can be adopted according to the properties of the oil in the cleaned tank, thereby greatly improving the on-site construction efficiency on the basis of greatly reducing the on-site electricity consumption.

[0047] like Figure 5 As shown, the tank top cleaning machine spraying system includes a cleaning machine 19 temporarily installed on the top of the storage tank 8 to be cleaned, a cleaning loop 17 and a cleaning machine branch line 18. The cleaning loop 17 is connected to the first vertical pipe 15 and the second vertical pipe 16 respectively. A plurality of cleaning machine branches 18 are evenly distributed on the cleaning loop 17, and a cleaning machine 19 is installed at the end of each cleaning machine branch line 18. The cleaning machine 19 is installed in the support sleeve of the floating roof and is preferably evenly distributed. The cleaning loop 17 and the cleaning machine branch line 18 should have different calibers, so that the function of pressurizing the cleaning machine 19 can be realized.

[0048] Reference Figure 5 The cleaning loop 17 is connected to the first vertical pipe 15 and the second vertical pipe 16 respectively. The cleaning loop 17 is provided with valves 13 and 14 on both sides of the connection end of the first vertical pipe 15, and the cleaning loop 17 is provided with valves 15 and 16 on both sides of the connection end of the second vertical pipe 16. Through the switch combination of valves 13, 14, 15, and 16, each vertical pipe can be completely independently supplied with the cleaning medium required for the cleaning machine in its respective responsible area, and only one vertical pipe can be used to meet the process of supplying the cleaning medium required for the cleaning machine to be sprayed. Process, such as opening valve 13 and valve 16, closing valve 14 and valve 15, the cleaning medium supplied in the first vertical pipe 15 can meet the injection requirements of cleaning machines Q1~Q8, and the cleaning medium supplied in the second vertical pipe 16 can meet the injection requirements of cleaning machines Q9~Q15; if valve 13, valve 15, valve 16 are opened, valve 14 is closed, the cleaning medium supplied in the first vertical pipe 15 can meet the injection requirements of all cleaning machines; open valve 13, valve 14, valve 15, close valve 16, the cleaning medium supplied in the second vertical pipe 16 can meet the injection requirements of all cleaning machines. The different use process of the two vertical pipes can be fully matched with the different operation process of the two cleaning pumps.

[0049] like Figure 3 As shown, the hot water circulation cleaning system 4 is composed of a vacuum suction device 5, an oil discharge pump 9, a first cleaning pump 12, a second cleaning pump 13, an oil-water separator 14 and related pipeline valves. Hot water cleaning is mainly a process of using hot water to perform a final comprehensive hot water flushing on the inner surface of the cleaned storage tank 8 in the later stage of mechanical cleaning of the storage tank. During hot water cleaning, the second switch valve 22 and the fourth switch valve 24 should be closed. After the oily wastewater in the cleaned storage tank 8 is automatically sucked into the vacuum suction device 5 by the oil product suction system 1, the oil discharge pump 9 is first used to transport the oily wastewater to the oil-water separator 14. After the separated water is sucked by two cleaning pumps, it passes through the double vertical pipe cleaning system 3 and the tank top cleaning machine injection system to realize the process of automatic hot water circulation cleaning in the tank.

[0050] Including an inert gas replacement system. When the cleaning machine sprays, static electricity will be generated. In order to prevent the occurrence of fire and explosion accidents when the cleaning machine sprays, it is necessary to inject inert gas into the cleaned storage tank 8 and monitor the oxygen concentration in the tank in real time. The inert gas replacement system includes a monitoring device installed in the cleaned storage tank 8 and an injection device for injecting inert gas into the cleaning storage tank 8. The monitoring device monitors the oxygen concentration in the cleaned storage tank 8 in real time. Only when the oxygen concentration in the tank is lower than 8% VOL can the cleaning machine be turned on for mechanical cleaning. The oxygen concentration data in the tank is interlocked with the entire system. Once the oxygen concentration in the tank exceeds the standard, the system will automatically stop the operation of the cleaning pump while issuing an alarm, fully ensuring the safety of the operation.

Claims

1. A double vertical pipe floating roof tank mechanical cleaning system, characterized in that: The invention comprises a vacuum suction device (5), a storage tank to be cleaned (8), an oil receiving storage tank (11) and an oil-water separator (14); the oil receiving storage tank (11) is provided with a suction pipeline (7), a first vertical pipe (15) and a second vertical pipe (16), respectively; a tank top cleaning machine spray system connected to the first vertical pipe (15) and the second vertical pipe (16) is arranged in the oil receiving storage tank (11); one end of the suction pipeline (7) is connected to the vacuum suction device (5); and a transfer pipeline (10), a first cleaning pipeline (20) and a second cleaning pipeline (21) are arranged in parallel on the vacuum suction device (5); One end of the first cleaning pipeline (20) is connected to the first vertical pipe (15), and one end of the second cleaning pipeline (21) is connected to the second vertical pipe (16). A first connecting pipeline (29) is provided between one end of the first cleaning pipeline (20) and one end of the second cleaning pipeline (21). A first switch valve (27) is provided on the first connecting pipeline (29). A second switch valve (22), a first cleaning pump (12), a third switch valve (23) and a first check valve (26) are provided in sequence on the first cleaning pipeline (20) from the vacuum suction device (5) toward the first vertical pipe (15). The second cleaning pipeline (21) ) are provided with a fourth switch valve (24), a second cleaning pump (13), a fifth switch valve (25) and a second check valve (28) in sequence from the vacuum suction device (5) to the second vertical pipe (16); a second connecting pipeline (30) is provided between the first cleaning pipeline (20) and the second cleaning pipeline (21); a connection point of one end of the second connecting pipeline (30) is located between the second switch valve (22) and the first cleaning pump (12); a connection point of the other end of the second connecting pipeline (30) is located between the fourth switch valve (24) and the second cleaning pump (13); and a sixth switch valve (31) is provided on the second connecting pipeline (30); One end of the transfer pipeline (10) is bifurcated into three branch pipelines (34), one branch pipeline (34) is connected to one end of the second cleaning pipeline (21), one branch pipeline (34) is connected to the oil receiving storage tank (11), and another branch pipeline (34) is connected to the oil-water separator (14). Each branch pipeline (34) is installed with a seventh switch valve (40). The transfer pipeline (10) is provided with an oil discharge pump (9), a third check valve (37) and a fourth check valve (38) in sequence from the vacuum suction device (5) to the three branch pipelines (34). A third connecting pipeline (32) is provided between the second cleaning pipeline (21) and the transfer pipeline (10), and an eighth switch valve (33) is installed on the third connecting pipeline (32). The connection point of one end of the third connecting pipeline (32) is located at the eighth switch valve (33). The third one-way valve (37) and the fourth one-way valve (38) are connected to each other. The connection point of the other end of the third connecting pipeline (32) is located between the fourth switch valve (24) and the second cleaning pump (13). The oil-water separator (14) is connected to a fourth connecting pipeline (35). One end of the fourth connecting pipeline (35) is connected to the first cleaning pipeline (20). The connection point of one end of the fourth connecting pipeline (35) is located between the second switch valve (22) and the first cleaning pump (12). A ninth switch valve (36) is installed on the fourth connecting pipeline (35). A tenth switch valve (39) is provided on the suction pipeline (7) between the oil discharge pump (9) and the vacuum suction device (5) and between the oil discharge pump (9) and the third one-way valve (37). A twelfth switch valve (42) is provided on the suction pipeline (7).

2. A double vertical pipe floating roof tank mechanical cleaning system according to claim 1, characterized in that: Two filters (6) are arranged in parallel between the vacuum suction device (5) and the suction pipeline (7).

3. A double vertical pipe floating roof tank mechanical cleaning system according to claim 2, characterized in that: Two eleventh switch valves (41) are provided on each parallel pipeline between the vacuum suction device (5) and the suction pipeline (7), and the two eleventh switch valves (41) are respectively located on both sides of the corresponding filter (6).

4. A double vertical pipe floating roof tank mechanical cleaning system according to claim 1, characterized in that: The vacuum suction device (5) comprises a vacuum pump, a vacuum tank and auxiliary equipment. The vacuum pump is connected to the vacuum tank. The gas in the vacuum tank is extracted through the suction action of the vacuum pump, so that negative pressure is generated in the vacuum tank.

5. A double vertical pipe floating roof tank mechanical cleaning system according to claim 1, characterized in that: It also includes an inert gas replacement system, which includes a monitoring device installed in the cleaned storage tank (8) and an injection device for injecting inert gas into the cleaning storage tank (8), and the monitoring device monitors the oxygen concentration in the cleaned storage tank (8) in real time.

6. A double vertical pipe floating roof tank mechanical cleaning system according to claim 1, characterized in that: The tank top cleaning machine spray system comprises a cleaning machine (19) temporarily installed on the tank top of the storage tank (8) to be cleaned, a cleaning loop (17) and a cleaning machine branch line (18), wherein the cleaning loop (17) is respectively connected to the first vertical pipe (15) and the second vertical pipe (16), and a plurality of cleaning machine branch lines (18) are evenly distributed on the cleaning loop (17), and a cleaning machine (19) is installed at the end of each cleaning machine branch line (18).

7. A double vertical pipe floating roof tank mechanical cleaning system according to claim 6, characterized in that: The diameter of the cleaning loop line (17) is larger than the diameter of the cleaning machine branch line (18).

8. The double vertical pipe floating roof tank mechanical cleaning system according to claim 1 is characterized by: The first vertical pipe (15) is provided with a thirteenth switch valve (43), and the second vertical pipe (16) is provided with a fourteenth switch valve (44).

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