Floating disc bottom falling protection system for floating roof storage tank
By using a liquid nitrogen recovery system and a nitrogen injection system, and by utilizing components such as liquid nitrogen tanks, oil-gas condensers, and purified waste nitrogen storage tanks, the environmental pollution problem during oil storage tank recovery has been solved, and the purification of mixed gas and the recycling of energy have been achieved.
Patent Information
- Application Number
- CN202520433210.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-13
- Publication Date
- 2026-01-06
- Estimated Expiration
- 2035-03-13
AI Technical Summary
When existing oil storage tanks receive oil, the unpurified mixture of gas is directly released into the atmosphere, causing environmental pollution.
The system employs a liquid nitrogen recovery system and a nitrogen injection system, which remove volatile organic compounds from the mixed gas through components such as liquid nitrogen tanks, oil-gas condensers, condensate tanks, and purified waste nitrogen storage tanks, and recycles nitrogen to reduce emissions.
It achieves the purification of the mixed gas, reduces the emission of volatile organic compounds, saves energy, and avoids environmental pollution.
Smart Images
Figure CN223765214U_ABST
Abstract
Description
Technical Field
[0001] This utility model belongs to the field of petroleum storage and transportation technology, specifically, it relates to a floating roof tank floating roof bottom protection system. Background Technology
[0002] Nowadays, to reduce the evaporation of media inside oil storage tanks and save energy by minimizing losses, floating roofs are installed inside these tanks. Additionally, to facilitate oil receiving and dispatching operations, automatic vent valves and vent hoods are installed on the floating roofs.
[0003] During oil recovery, as the oil level rises, the gas mixture between the oil level and the floating roof is directly discharged from the gas collection hood. Since this mixture contains pollutants such as volatile organic compounds, its direct release into the atmosphere without purification will have adverse environmental impacts. Utility Model Content
[0004] To overcome the above shortcomings, this utility model provides a floating roof tank floating plate bottom protection system, which aims to solve the problem that the mixed gas emitted directly into the atmosphere without purification during the oil recovery process of existing oil storage tanks will have an adverse impact on the environment.
[0005] This utility model is specifically implemented as follows:
[0006] A floating roof tank floating roof bottom protection system includes:
[0007] Oil storage tanks;
[0008] A floating roof is installed inside the oil storage tank. The floating roof is equipped with an automatic vent valve and a gas collection hood. The gas collection hood is equipped with a first pressure sensor.
[0009] A liquid nitrogen recovery system includes a liquid nitrogen tank, a liquid nitrogen valve, an oil-gas condenser, an oil-gas switch valve, a condensate tank, and a purified waste nitrogen storage tank. The first inlet of the oil-gas condenser is connected to the outlet of the liquid nitrogen tank through a first pipe. The liquid nitrogen valve is located on the first pipe. The second inlet of the oil-gas condenser is connected to the outlet of the gas collection hood through a second pipe. The oil-gas switch valve is located on the second pipe. The first outlet of the oil-gas condenser and the first inlet of the purified waste nitrogen storage tank are both connected to the condensate tank through a T-junction.
[0010] Furthermore, the first outlet of the purified nitrogen storage tank is connected to the inlet of the gas collection hood via a third pipe, and the liquid nitrogen recovery system includes a nitrogen switch valve, which is located on the third pipe.
[0011] Furthermore, the liquid nitrogen recovery system includes a rewarming vaporizer, the inlet of which is connected to the second outlet of the oil-gas condenser via a fourth pipe, and the outlet of which is connected to the inlet of the purified waste nitrogen storage tank via a fifth pipe.
[0012] Furthermore, the purified nitrogen storage tank is equipped with a second pressure sensor and / or a first oxygen content sensor.
[0013] Furthermore, the liquid nitrogen recovery system includes a first vent valve, and the second outlet of the purified waste nitrogen storage tank is connected to a sixth pipeline, with the first vent valve located on the sixth pipeline.
[0014] Furthermore, the liquid nitrogen recovery system includes an exhaust stack, the inlet of which is connected to the end of the sixth pipe opposite to the first vent valve.
[0015] Furthermore, it includes a nitrogen injection system, which includes a nitrogen storage tank. The first outlet of the nitrogen storage tank is connected to the third pipeline via a seventh pipeline. Both the third pipeline and the seventh pipeline are equipped with a tank switch valve.
[0016] Furthermore, the inlet of the nitrogen storage tank is connected to the end of the fifth pipeline away from the rewarming vaporizer, the nitrogen storage tank is equipped with a third pressure sensor, the nitrogen injection system includes a second vent valve, the second outlet of the nitrogen storage tank is connected to the second inlet of the purified waste nitrogen storage tank through an eighth pipeline, and the second vent valve is located on the eighth pipeline.
[0017] Furthermore, it includes a nitrogen replenishment device, the outlet of which is connected to the third inlet of the oil-gas condenser via a ninth pipe.
[0018] Furthermore, a second oxygen content sensor is provided on the gas collection hood.
[0019] Compared with the prior art, the beneficial effects of this utility model are:
[0020] (1) This utility model can remove volatile organic compounds from the mixed gas during oil collection by using a liquid nitrogen tank, an oil-gas condenser, and a condensate tank, thereby obtaining purified nitrogen. This not only enables nitrogen to be recycled and saves energy, but also reduces the emission of volatile organic compounds and avoids environmental pollution.
[0021] (2) This utility model uses a reheat vaporizer to vaporize liquid nitrogen into nitrogen gas in an oil and gas condenser, and then further heats and vaporizes the nitrogen gas flowing into the reheat vaporizer. The heated nitrogen gas is then stored for use when nitrogen injection is needed to recover oil, thereby further saving energy. Attached Figure Description
[0022] To more clearly illustrate the technical solutions of the embodiments of this utility model, the drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this utility model and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained from these drawings without creative effort.
[0023] Figure 1 This is a schematic diagram of the structure of a floating roof tank float protection system provided by an embodiment of the present invention;
[0024] Figure 2 This is a schematic diagram of the operation of a floating roof tank float protection system during oil recovery, provided by an embodiment of this utility model.
[0025] Figure 3 This is a schematic diagram of the operation of a floating roof tank floating disc bottom protection system during oil dispensing, provided by an embodiment of this utility model.
[0026] Explanation of reference numerals in the attached figures:
[0027] 1. Oil storage tanks;
[0028] 2. Floating roof; 21. Automatic vent valve; 22. Gas collection hood; 23. First pressure sensor; 24. Second oxygen content sensor;
[0029] 3. Liquid nitrogen recovery system; 31. Liquid nitrogen tank; 311. Tank switch valve; 32. Liquid nitrogen valve; 33. Oil-gas condenser; 34. Oil-gas switch valve; 35. Condensate tank; 36. Purified waste nitrogen storage tank; 361. Second pressure sensor; 362. First oxygen content sensor; 37. Nitrogen switch valve; 38. Reheat vaporizer; 39. First vent valve; 310. Exhaust stack;
[0030] 4. Nitrogen injection system; 411. Third pressure sensor; 41. Nitrogen storage tank; 42. Second relief valve;
[0031] 5. Nitrogen replenishment device;
[0032] 6. First pipe; 62. Second pipe; 63. Tee pipe; 64. Third pipe; 65. Fourth pipe; 66. Fifth pipe; 67. Sixth pipe; 68. Seventh pipe; 69. Eighth pipe; 610. Ninth pipe. Detailed Implementation
[0033] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this utility model.
[0034] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.
[0035] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.
[0036] In the description of this utility model, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this utility model and simplifying the description, and are not intended to indicate or imply that the device or component referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model.
[0037] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this utility model, "a plurality of" means two or more, unless otherwise explicitly specified.
[0038] Please see Figure 1As shown, this utility model provides a technical solution: a floating roof tank floating plate 2 bottom protection system, including an oil storage tank 1, a floating plate 2, and a liquid nitrogen recovery system 3. The floating plate 2 is located inside the oil storage tank 1. An automatic venting valve 21 and a gas collection hood 22 are respectively provided on the floating plate 2. A first pressure sensor 23 is provided on the gas collection hood 22. The liquid nitrogen recovery system 3 includes a liquid nitrogen tank 31, a liquid nitrogen valve 32, an oil-gas condenser 33, an oil-gas switching valve 34, a condensate tank 35, and a purified waste nitrogen storage tank 36. The first inlet of the oil-gas condenser 33 is connected to the outlet of the liquid nitrogen tank 31 through a first pipe 6. The liquid nitrogen valve 32 is located on the first pipe 6. The second inlet of the oil-gas condenser 33 is connected to the outlet of the gas collection hood 22 through a second pipe 62. The oil-gas switching valve 34 is located on the second pipe 62. The first outlet of the oil-gas condenser 33 and the first inlet of the purified waste nitrogen storage tank 36 are both connected to the condensate tank 35 through a three-way pipe 63.
[0039] In practical applications, after the floating roof 2 reaches the bottom, the automatic vent valve 21 opens. During the next oil recovery operation, the oil level below the floating roof 2 rises, and the pressure inside the gas collection hood 22 gradually increases. When the first pressure sensor 23 detects the pressure increase, the oil-gas switch valve 34 and the liquid nitrogen valve 32 are opened, allowing the mixture of oil, gas, and nitrogen below the floating roof 2 to sequentially pass through the automatic vent valve 21, the gas collection hood 22, and the second pipe 62 into the oil-gas condenser 33. Simultaneously, liquid nitrogen inside the liquid nitrogen tank 31 enters the oil-gas condenser 33 through the liquid nitrogen valve 32 and the first pipe 6. The low-temperature liquid nitrogen condenses the volatile organic compounds in the mixture into a condensate. The condensate then flows through the three-way pipe 63 into the condensate tank 35, where it is condensed to remove volatile organic compounds. Finally, the resulting purified nitrogen flows through the three-way pipe 63 into the purified nitrogen storage tank 36. In this way, volatile organic compounds in the mixture can be removed during oil recovery, thus obtaining purified nitrogen. This not only enables nitrogen to be recycled and saves energy, but also reduces emissions of volatile organic compounds and avoids environmental pollution.
[0040] Please see Figure 1 As shown, in one possible embodiment, the first outlet of the purified nitrogen storage tank 36 is connected to the inlet of the gas collection hood 22 via a third pipe 64, and the liquid nitrogen recovery system 3 includes a nitrogen switch valve 37, which is located on the third pipe 64.
[0041] In practical applications, during oil dispensing, the oil level below the floating roof 2 drops, and the pressure inside the gas collection hood 22 also decreases accordingly. When the first pressure sensor 23 detects the pressure drop, the nitrogen switch valve 37 is opened, and the purified nitrogen from the purified nitrogen storage tank 36 flows sequentially through the third pipe 64, the gas collection hood 22, and the automatic vent valve 21 to the area below the floating roof 2, inerting the oil and gas space below the floating roof 2 and preventing the formation of explosive gases with excessive oxygen content.
[0042] Please see Figure 1 As shown, in one possible embodiment, the liquid nitrogen recovery system 3 includes a rewarming vaporizer 38, the inlet of which is connected to the second outlet of the oil-gas condenser 33 via a fourth pipe 65, and the outlet of which is connected to the inlet of the purified waste nitrogen storage tank 36 via a fifth pipe 66.
[0043] In practical applications, during oil recovery, liquid nitrogen absorbs heat and vaporizes into nitrogen gas in the oil-gas condenser 33, and then flows through the fourth pipe 65 into the reheat vaporizer 38 for further heating and vaporization. The heated nitrogen gas then flows through the fifth pipe 66 into the purified waste nitrogen storage tank 36 for storage, to be used when nitrogen injection is needed for oil recovery, thereby further saving energy.
[0044] Please see Figure 1 As shown, in one possible embodiment, the purified nitrogen storage tank 36 is equipped with a second pressure sensor 361 and / or a first oxygen content sensor 362.
[0045] In practical applications, the second pressure sensor 361 mainly detects the pressure of the purified nitrogen in the purified nitrogen storage tank 36; the first oxygen content sensor 362 mainly detects the oxygen content of the purified nitrogen in the purified nitrogen storage tank 36.
[0046] Please see Figure 1 As shown, in one possible embodiment, the liquid nitrogen recovery system 3 includes a first vent valve 39, and the second outlet of the purified waste nitrogen storage tank 36 is connected to a sixth pipe 67, with the first vent valve 39 located on the sixth pipe 67.
[0047] In practical applications, when the second pressure sensor 361 detects that the pressure of the purified nitrogen in the purified nitrogen storage tank 36 is too high or the first oxygen content sensor 362 detects that the oxygen content of the purified nitrogen in the purified nitrogen storage tank 36 exceeds the standard, the first relief valve 39 is opened to discharge the purified nitrogen in the purified nitrogen storage tank 36, thus preventing potential safety hazards.
[0048] Please see Figure 1 As shown, in one possible embodiment, the liquid nitrogen recovery system 3 includes an exhaust stack 310, the inlet of which is connected to the end of the sixth pipe 67 away from the first vent valve 39.
[0049] In practical applications, purified nitrogen can be efficiently and safely discharged into the atmosphere through the exhaust stack 310, thereby ensuring the smooth operation of the system.
[0050] Please see Figure 1 As shown, in one possible embodiment, the protection system includes a nitrogen injection system 4, which includes a nitrogen storage tank 41. The first outlet of the nitrogen storage tank 41 is connected to a third pipe 64 via a seventh pipe 68. Both the third pipe 64 and the seventh pipe 68 are equipped with a storage tank switch valve 311.
[0051] In practical applications, when injecting nitrogen, the storage tank switch valve 311 on the third pipe 64 or the seventh pipe 68 can be opened to inject nitrogen below the floating roof 2. For example, by opening the nitrogen switch valve 37 and the storage tank switch valve 311 on the seventh pipe 68, the nitrogen in the nitrogen storage tank 41 flows sequentially through the seventh pipe 68 and the third pipe 64 to the bottom of the floating roof 2.
[0052] Please see Figure 1 As shown, in one possible embodiment, the inlet of the nitrogen storage tank 41 is connected to the end of the fifth pipe 66 away from the reheat vaporizer 38. The nitrogen storage tank 41 is equipped with a third pressure sensor 411. The nitrogen injection system 4 includes a second relief valve 42. The second outlet of the nitrogen storage tank 41 is connected to the second inlet of the purified waste nitrogen storage tank 36 through an eighth pipe 69. The second relief valve 42 is located on the eighth pipe 69.
[0053] In practical applications, during oil recovery, liquid nitrogen absorbs heat and vaporizes into nitrogen gas in the oil-gas condenser 33. After further heating and vaporization in the reheat vaporizer 38, the heated nitrogen gas flows into the nitrogen storage tank 41 through the fifth pipe 66. Simultaneously, the third pressure sensor 411 detects the nitrogen pressure in the nitrogen storage tank 41. When the nitrogen pressure in the nitrogen storage tank 41 is too high, the second relief valve 42 is opened, and the nitrogen in the nitrogen storage tank 41 flows into the purified waste nitrogen storage tank 36 through the eighth pipe 69, thereby protecting the purified waste nitrogen storage tank 36.
[0054] Please see Figure 1 As shown, in one possible embodiment, the protection system includes a nitrogen replenishment device 5, the outlet of which is connected to the third inlet of the oil-gas condenser 33 via a ninth conduit 610.
[0055] For example, the nitrogen replenishment device 5 can be a nitrogen transport vehicle, etc.
[0056] In practical applications, the nitrogen replenishment device 5 can replenish nitrogen to the purified waste nitrogen storage tank 36, ensuring that the purified waste nitrogen storage tank 36 has sufficient nitrogen.
[0057] Please see Figure 1 As shown, in one possible embodiment, a second oxygen content sensor 24 is provided on the gas collection hood 22.
[0058] In practical applications, the second oxygen content sensor 24 primarily detects the oxygen content of the nitrogen gas inside the gas collection hood 22. When the oxygen content exceeds the standard, the liquid nitrogen recovery system 3 or the nitrogen injection system 4 can also inject nitrogen into the gas collection hood 22.
[0059] In addition, since the floating roof 2 does not frequently need to be lowered to the bottom, the liquid nitrogen recovery system 3 and the nitrogen injection system 4 can be configured as vehicle-mounted mobile systems. When the storage tank needs to lower the floating roof 2 to the bottom, the liquid nitrogen recovery system 3 and the nitrogen injection system 4 can be transported to the vicinity of the storage tank and connected to the fixed nitrogen pipeline and oil and gas pipeline of the oil storage tank 1, after which the floating roof 2 can be lowered to the bottom.
[0060] Please see Figure 2 As shown, the specific process for oil recovery in this utility model is as follows:
[0061] After the floating roof 2 reaches the bottom, the automatic vent valve 21 opens. During the next oil recovery operation, the oil level below the floating roof 2 rises, and the pressure inside the gas collection hood 22 gradually increases. When the first pressure sensor 23 detects the pressure increase, the oil-gas switch valve 34 and the liquid nitrogen valve 32 are opened, allowing the mixture of oil, gas, and nitrogen below the floating roof 2 to pass sequentially through the automatic vent valve 21, the gas collection hood 22, and the second pipe 62 into the oil-gas condenser 33. Simultaneously, the liquid nitrogen inside the liquid nitrogen tank 31 enters the oil-gas condenser 33 through the liquid nitrogen valve 32 and the first pipe 6. The low-temperature liquid nitrogen condenses the volatile organic compounds in the mixture into a condensate. The condensate then enters the condensate tank 35 through the three-way pipe 63, where it is condensed to remove volatile organic compounds. Finally, the resulting purified waste nitrogen flows into the purified waste nitrogen storage tank 36 through the three-way pipe 63. Liquid nitrogen absorbs heat and vaporizes into nitrogen gas in the oil-gas condenser 33, and then flows through the fourth pipe 65 into the reheat vaporizer 38 for further heating and vaporization. The heated nitrogen gas then flows through the fifth pipe 66 into the nitrogen storage tank 41 for storage. When the third pressure sensor 411 detects that the nitrogen pressure in the nitrogen storage tank 41 is too high, the second relief valve 42 is opened, allowing nitrogen gas to flow through the eighth pipe 69 into the purified waste nitrogen storage tank 36. When the second pressure sensor 361 detects that the purified waste nitrogen pressure in the purified waste nitrogen storage tank 36 is too high, or the first oxygen content sensor 362 senses that the oxygen content of the purified waste nitrogen in the purified waste nitrogen storage tank 36 exceeds the standard, the first relief valve 39 is opened, discharging the purified waste nitrogen into the exhaust stack 310.
[0062] Please see Figure 2 As shown, the specific process for oil recovery in this utility model is as follows:
[0063] During oil dispensing, the oil level below the floating roof 2 drops, and the pressure inside the gas collection hood 22 also decreases accordingly. When the first pressure sensor 23 detects a pressure drop or the second oxygen content sensor 24 detects excessive oxygen content, the nitrogen switch valve 37 and the storage tank switch valve 311 on the third pipeline 64 are opened. The purified nitrogen from the purified nitrogen storage tank 36 flows sequentially through the third pipeline 64, the gas collection hood 22, and the automatic vent valve 21 to the area below the floating roof 2. Alternatively, the nitrogen switch valve 37 and the storage tank switch valve 311 on the seventh pipeline 68 are opened, and the nitrogen from the nitrogen storage tank 41 flows sequentially through the seventh pipeline 68 and the third pipeline 64 to the area below the floating roof 2, thereby inerting the oil and gas space below the floating roof 2.
[0064] The above are merely preferred embodiments of this utility model and are not intended to limit the scope of this utility model. Various modifications and variations can be made to this utility model by those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of this utility model should be included within the protection scope of this utility model.
Claims
1. A floating roof tank deck sagging protection system, characterized by, The application relates to an oil product storage tank (1) and a liquid nitrogen recovery system (3) and a nitrogen injection system (4). The oil product storage tank (1) comprises a floating plate (2) provided in the oil product storage tank (1), wherein an automatic vent valve (21) and a gas collecting hood (22) are arranged on the floating plate (2), and a first pressure sensor (23) is arranged on the gas collecting hood (22). The liquid nitrogen recovery system (3) comprises a liquid nitrogen tank (31), a liquid nitrogen valve (32), an oil gas condenser (33), an oil gas switch valve (34), a condensate tank (35) and a purified waste nitrogen storage tank (36), wherein a first inlet of the oil gas condenser (33) is connected to an outlet of the liquid nitrogen tank (31) through a first pipeline (6), the liquid nitrogen valve (32) is arranged on the first pipeline (6), a second inlet of the oil gas condenser (33) is connected to an outlet of the gas collecting hood (22) through a second pipeline (62), the oil gas switch valve (34) is arranged on the second pipeline (62), a first outlet of the oil gas condenser (33) and a first inlet of the purified waste nitrogen storage tank (36) are both connected to the condensate tank (35) through a three-way pipe (63). A first outlet of the purified waste nitrogen storage tank (36) is connected to an inlet of the gas collecting hood (22) through a third pipeline (64), and the liquid nitrogen recovery system (3) comprises a nitrogen switch valve (37), wherein the nitrogen switch valve (37) is arranged on the third pipeline (64).
2. A floating roof deck fall protection system for a floating roof storage tank as defined in claim 1, wherein, The liquid nitrogen recovery system (3) comprises a re-warming vaporizer (38), wherein an inlet of the re-warming vaporizer (38) is connected to a second outlet of the oil gas condenser (33) through a fourth pipeline (65), and an outlet of the re-warming vaporizer (38) is connected to an inlet of the purified waste nitrogen storage tank (36) through a fifth pipeline (66).
3. A floating roof deck fall protection system for a floating roof storage tank as defined in claim 2, wherein, A second pressure sensor (361) and / or a first oxygen content sensor (362) are arranged on the purified waste nitrogen storage tank (36).
4. A floating roof deck fall protection system for a floating roof storage tank as defined in claim 3, wherein, The liquid nitrogen recovery system (3) comprises a first relief valve (39), a second outlet of the purified waste nitrogen storage tank (36) is connected to a sixth pipeline (67), and the first relief valve (39) is arranged on the sixth pipeline (67).
5. A floating roof deck fall protection system for a floating roof storage tank as defined in claim 4, wherein, The liquid nitrogen recovery system (3) comprises an exhaust cylinder (310), and an inlet of the exhaust cylinder (310) is connected to one end of the sixth pipeline (67) away from the first relief valve (39).
6. A floating roof deck fall protection system for a floating roof storage tank as defined in claim 5, wherein, The application further relates to a nitrogen injection system (4), wherein the nitrogen injection system (4) comprises a nitrogen storage tank (41), a first outlet of the nitrogen storage tank (41) is connected to the third pipeline (64) through a seventh pipeline (68), and a storage tank switch valve (311) is arranged on the third pipeline (64) and the seventh pipeline (68).
7. A floating roof deck fall protection system for a floating roof tank as defined in claim 3, wherein, An inlet of the nitrogen storage tank (41) is connected to one end of the fifth pipeline (66) away from the re-warming vaporizer (38), a third pressure sensor (411) is arranged on the nitrogen storage tank (41), the nitrogen injection system (4) comprises a second relief valve (42), a second outlet of the nitrogen storage tank (41) is connected to a second inlet of the purified waste nitrogen storage tank (36) through an eighth pipeline (69), and the second relief valve (42) is arranged on the eighth pipeline (69).
8. A floating roof deck fall protection system for a floating roof storage tank as defined in claim 7, wherein, 9. A floating roof fall-to-bottom protection system for a floating roof storage tank according to any one of claims 1 to 8, characterized in that, The nitrogen supplement device (5) is connected to the third inlet of the oil gas condenser (33) through a ninth pipeline (610).
10. A floating roof fall-to-bottom protection system for a floating roof storage tank according to any one of claims 1 to 9, characterized in that, The gas hood (22) is provided with a second oxygen content sensor (24).