Inert gas explosion-proof protection system of ultra-large oil tanker

Abstract

The inert gas explosion-proof protection system for the ultra-large oil tanker is applied to the field of ships, dynamic adjustment of the water seal depth is achieved through a segmentation barrel and a hydraulic cylinder, in the gas injection sealing stage, the segmentation barrel and a gas injection pipe are matched to lift up seawater on the upper portion of a tower body, the seawater below the segmentation barrel is made to conduct water seal on the gas injection pipe, and the water seal effect is achieved. Therefore, the water seal depth of the gas injection pipe is reduced, the back pressure which needs to be overcome when the air blower conveys inert gas is reduced, the operation power of the air blower is reduced, the purposes of saving energy and reducing consumption are achieved, and during static sealing, the water seal effect is further improved by increasing the water seal depth. Besides, through a safety pipe and a normally-open solenoid valve on the hydraulic cylinder, under the condition of sudden power failure, the self weight of the segmentation barrel and the weight of seawater in the segmentation barrel are utilized, so that the segmentation barrel moves downwards to return to the initial position and automatically returns to the water seal depth required by static sealing, and the safety and the water seal effect of the water seal tower after power failure are improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of ships, in particular to an inert gas explosion-proof protection system for very large crude carriers. BACKGROUND

[0002] The inert gas protection system for very large crude carriers is composed of an inert gas generator, a scrubbing tower, a blower, a deck water seal tower and a distribution pipeline. The inert gas generator generates inert gas with oxygen content less than 5% by burning fuel or recovering boiler flue gas. After being cooled, desulfurized, dedusted and dehumidified by the scrubbing tower, the inert gas is delivered to the deck water seal tower by the electric blower. The deck water seal realizes one-way conduction of gas by using a water seal structure to prevent backflow of oil gas. Finally, the inert gas is injected into each cargo tank through the distribution pipeline to maintain the oxygen content in the tank below 8% and keep a positive pressure, forming a non-flammable environment to ensure safe navigation.

[0003] The existing patent with publication number CN105909975B discloses a ship inert gas pipeline oil and gas check valve system. The inert gas pipeline is connected with a seawater pump through a deck water seal tower, and key components such as a swing check valve and a water seal breather valve are used to realize one-way flow control of oil and gas, so that the oil tanker can effectively prevent the backflow of oil gas in the cargo tank to the engine room under various working conditions, ensuring the safety and reliability of the system.

[0004] The existing patent with publication number CN111547186B discloses a deck water seal water discharge device and a ship. A breather assembly with an overflow valve is arranged on the deck water seal water discharge device to selectively connect the discharge pipe with the atmosphere, realize the discharge of residual gas and provide back pressure overcoming function, ensure smooth discharge of water seal water, and prevent discharge water from overflowing to the deck, improving the safety and reliability of the device.

[0005] The above-mentioned existing technology discloses a technical solution for realizing one-way control of oil and gas flow by using a swing check valve and a water seal breather valve, and also discloses a technical solution for improving the smoothness and reliability of seawater discharge by using a breather assembly arranged on the discharge pipe. However, the existing technology still has deficiencies. The water seal depth of the current deck water seal tower is fixedly designed. When the water seal depth is increased, the blower needs to overcome greater seawater static pressure, resulting in significant increase in energy consumption. Reducing the water seal depth can reduce energy consumption, but it will weaken the water seal effect, making it difficult to balance safety and economy. SUMMARY

[0006] The core of the present application is to adjust the water seal depth by a liftable split cylinder to solve the problem that safety and economy cannot be balanced due to the unadjustable water seal depth in the prior art. At the same time, a safety pipe and a normally open electromagnetic valve installed on the hydraulic cylinder are used to automatically restore the water seal depth required for static sealing in the event of a power failure.

[0007] To solve the above problems, the present application adopts the following technical solutions.

[0008] An inert gas explosion-proof protection system for a very large crude carrier (VLCC) includes a water-sealed tower. The water-sealed tower includes a tower body, with an injection pipe fixedly connected to the top wall of the tower body extending to the lower part of its inner cavity. An exhaust pipe connected to the upper end of the tower body and communicating with its inner cavity is fixedly connected to the upper end of the tower body. The tower body is filled with sealed seawater with a liquid level higher than the opening height of the lower end of the injection pipe. The upper end of the injection pipe is fixedly connected to the outlet of a blower. The inlet of the blower is connected to the outlet of a scrubbing tower. The inlet of the scrubbing tower is connected to the outlet of an inert gas generator. The outer end of the exhaust pipe is connected to the inner cavity of each cargo oil tank through a distribution pipe. Below the gas injection pipe is a dividing cylinder that slides through the inner wall of the tower. A central hole is opened at the bottom center of the dividing cylinder for the gas injection pipe to pass through, and multiple evenly distributed vertical channels are opened in its circumferential side wall. The central hole and vertical channels are used to connect the cavities located on both sides of the dividing cylinder inside the tower. The dividing cylinder is fixedly connected to the movable end of a pair of hydraulic cylinders. The fixed end of the hydraulic cylinder is fixedly connected to an installation ring, which is fixedly connected to the inner wall of the tower. The hydraulic cylinder is used to drive the dividing cylinder to move upward inside the tower. A water inlet pipe and an overflow pipe are fixedly connected to the side wall of the tower.

[0009] Furthermore, the tower body has a cylindrical structure, the gas injection pipe is inverted L-shaped and its lower part is located at the central axis of the tower body, and a demister is fixedly connected to the inner wall of the tower body above the mounting ring. A through hole for the gas injection pipe to pass through is opened at the center of the demister.

[0010] Furthermore, the dividing cylinder has a cylindrical structure with an open top. An inner sealing sleeve is fixedly connected to the inner wall of the central hole. The inner sealing sleeve is used to fill the contact gap between the central hole and the gas injection pipe. An outer sealing sleeve is fixedly connected to the circumferential side wall of the dividing cylinder. The outer sealing sleeve slides against the inner wall of the tower.

[0011] Furthermore, both the inner and outer sealing sleeves are made of rubber material, the outer edge of the lower opening of the air injection tube is rounded, and the inner edge of the upper opening of the inner sealing sleeve is rounded.

[0012] Furthermore, the water inlet pipe is an inverted U-shaped pipe, and the height of the connection between the water inlet pipe and the tower body is lower than the height of the lower end face of the dividing cylinder at its lowest point. A seawater pump is fixedly connected to the end of the water inlet pipe away from the tower body. The seawater pump injects seawater into the tower body through the water inlet pipe. A vent valve is fixedly connected to the center of the top of the water inlet pipe. The vent valve is used to balance the pressure inside the tower body.

[0013] Furthermore, the height of the connection between the overflow pipe and the tower body is lower than the height of the lower end face of the dividing cylinder when it is at its lowest point, and the height of the upper opening of the overflow pipe is lower than the height of the lower end face of the demister.

[0014] Furthermore, a liquid level sensor is fixedly connected to the lower end face of the mounting ring. The liquid level sensor is used to detect the seawater level in the tower body during static sealing. A liquid level sensor is fixedly connected to the lower end face of the dividing cylinder. The liquid level sensor is used to detect the seawater level below the dividing cylinder during gas injection sealing.

[0015] Furthermore, the hydraulic cylinder includes a cylinder body fixedly connected to the mounting ring, a piston rod slidably connected inside the cylinder body, the lower end of the piston rod being fixedly connected to the bottom plate of the dividing cylinder, a piston disc being fixedly connected to the upper end of the piston rod, the piston disc slidingly abutting against the inner wall of the cylinder body, and a safety tube being fixedly connected to the outer wall of the cylinder body. The safety tube is used to connect the cavities of the cylinder body located on both sides of the piston disc, and a normally open solenoid valve is fixedly connected to the safety tube. The normally open solenoid valve is used to make the safety tube open when the power is off.

[0016] Compared with the prior art, the advantages of this invention are: (1) The present invention achieves dynamic adjustment of water seal depth through the dividing cylinder and hydraulic cylinder. During the gas injection sealing stage, the dividing cylinder and the gas injection pipe work together to lift the seawater in the upper part of the tower body, so that the seawater below the dividing cylinder water seals the gas injection pipe, reducing the water seal depth of the gas injection pipe at this time, thereby reducing the back pressure that the blower needs to overcome when transporting inert gas, thus reducing the working power of the blower during gas injection, achieving energy saving and consumption reduction during gas injection sealing, and further improving the water seal effect by increasing the water seal depth during static sealing; in addition, by opening a vertical channel in the dividing cylinder shell wall, the airflow flows through the vertical channel after the central hole is blocked, realizing the flow of inert airflow.

[0017] (2) In the event of a sudden power failure, the present invention uses the safety pipe and normally open solenoid valve installed on the hydraulic cylinder to make the dividing cylinder move downward back to the initial position by utilizing the weight of the dividing cylinder itself and the weight of the seawater inside the dividing cylinder, and automatically restores the water seal depth required for static sealing, thereby improving the safety and water seal effect of the water seal tower after the power failure. Attached Figure Description

[0018] Figure 1 This is a three-dimensional structural diagram of the present invention; Figure 2 This is a schematic diagram of the internal structure of the water seal tower in this invention; Figure 3 This is a cross-sectional exploded view of the segmented cylinder in this invention; Figure 4 This is a schematic diagram showing the distribution of seawater during static sealing in this invention; Figure 5 This is a schematic diagram showing the flow of inert gas during the gas injection sealing process in this invention. Figure 6 for Figure 2 Enlarged structural diagram at point A; Figure 7This is a schematic diagram of the exploded assembly structure of the hydraulic cylinder and the dividing cylinder in this invention; Figure 8 This is a schematic diagram illustrating the flow of hydraulic oil when the power is interrupted according to the present invention.

[0019] Explanation of the labels in the diagram: 1. Water seal tower; 2. Blower; 3. Tower body; 4. Air injection pipe; 5. Exhaust pipe; 6. Demister; 7. Dividing cylinder; 701. Center hole; 702. Vertical channel; 8. Inner sealing sleeve; 9. Outer sealing sleeve; 10. Hydraulic cylinder; 11. Mounting ring; 12. Water inlet pipe; 13. Overflow pipe; 14. Vent valve; 15. Liquid level sensor one; 16. Liquid level sensor two; 17. Cylinder body; 18. Piston rod; 19. Piston disc; 20. Oil inlet pipe; 21. Safety pipe; 22. Normally open solenoid valve. Detailed Implementation

[0020] The technical solutions will now be clearly and completely described with reference to the accompanying drawings in the embodiments of the present invention.

[0021] First implementation method Please see Figures 1-2 In one embodiment of the present invention, an inert gas explosion-proof protection system for a very large crude carrier includes a water-sealed tower 1, the water-sealed tower 1 includes a tower body 3, the top wall of the tower body 3 is fixedly connected to an injection pipe 4 extending to the lower part of its inner cavity, the upper end of the tower body 3 is fixedly connected to an exhaust pipe 5 communicating with its inner cavity; the tower body 3 is filled with sealed seawater with a liquid level higher than the opening height of the lower end of the injection pipe 4, the upper end of the injection pipe 4 is fixedly connected to the outlet of a blower 2, the inlet of the blower 2 is connected to the outlet of a scrubbing tower, the inlet of the scrubbing tower is connected to the outlet of an inert gas generator, and the outer end of the exhaust pipe 5 is connected to the inner cavity of each cargo oil tank through a distribution pipe; Please see Figure 2 and Figure 3 Below the air injection pipe 4 is a dividing cylinder 7 that is slidably connected to the inner wall of the tower body 3. A central hole 701 is opened at the center of the bottom of the dividing cylinder 7 for the air injection pipe 4 to pass through, and multiple evenly distributed vertical channels 702 are opened in its circumferential side wall. The central hole 701 and the vertical channels 702 are used to connect the cavities located on both sides of the dividing cylinder 7 inside the tower body 3. The dividing cylinder 7 is fixedly connected to the movable end of a pair of hydraulic cylinders 10. The fixed end of the hydraulic cylinder 10 is fixedly connected to an installation ring 11. The installation ring 11 is fixedly connected to the inner wall of the tower body 3. The hydraulic cylinder 10 drives the dividing cylinder 7 to move upward, so that the air injection pipe 4 is inserted into the central hole 701. At this time, the cavities on both sides of the dividing cylinder 7 in the tower body 3 are connected through the vertical channels 702. The side wall of the tower body 3 is fixedly connected to a water inlet pipe 12 and an overflow pipe 13.

[0022] Specifically, the usage includes the following steps: Step 1, during static sealing, please refer to...Figure 4 The center hole 701 of the dividing cylinder 7 is located below the air injection pipe 4, and the water seal liquid level of the sealing seawater is higher than the upper end surface of the dividing cylinder 7. Specifically, at this time, it is in a static sealed state, and the height of the lower opening of the air injection pipe 4 from the seawater surface is the first water seal depth; Step two, when gas injection sealing is required, please refer to... Figure 4 and Figure 5 This includes the following sub-steps: S1, start hydraulic cylinder 10, hydraulic cylinder 10 drives the dividing cylinder 7 to move upward a set distance. At this time, the central hole 701 is blocked by the air injection pipe 4, and the vertical channel 702 connects the cavities located on both sides of the dividing cylinder 7 in the tower body 3. The seawater level below the dividing cylinder 7 is higher than the height of the lower opening of the air injection pipe 4. Specifically, during the rising process of the dividing cylinder 7, when the central hole 701 moves to the side wall of the air injection pipe 4, the air injection pipe 4 and the dividing cylinder 7 form an annular cavity. The seawater in the tower body 3 is divided into upper seawater located above the dividing cylinder 7 and lower seawater located below the dividing cylinder 7. As the dividing cylinder 7 rises, part of the upper seawater located above the annular cavity enters the lower seawater located below the dividing cylinder 7 through the vertical channel 702. Part of the seawater in the water column located in the air injection pipe 4 flows into the lower seawater under the action of gravity and negative pressure (the volume of the cavity below the dividing cylinder 7 increases). In addition, part of the seawater in the water inlet pipe 12 and the overflow pipe 13 also flows into the lower seawater under the action of gravity and negative pressure. S2, start blower 2, blower 2 pressurizes inert gas and injects it into the gas injection pipe 4, and then enters the seawater below the dividing cylinder 7 through the lower opening of the gas injection pipe 4. Then the inert gas moves to the cavity below the dividing cylinder 7 in the form of bubbles, and then enters the upper cavity of the tower body 3 above the dividing cylinder 7 through the vertical channel 702. Finally, the inert gas is discharged from the exhaust pipe 5 and then injected into each cargo oil tank through the distribution pipe.

[0023] Specifically, at this time, the air-sealed state is in which the liquid level of the seawater below is far from the opening at the lower end of the air-sealing pipe 4. This is the second water seal depth. Obviously, the second water seal depth is less than the first water seal depth. Step 3: After the air injection is completed, the hydraulic cylinder 10 is started again, causing the dividing cylinder 7 to move downwards by a set distance and return to the initial position. At this time, the seawater above and below the dividing cylinder 7 are connected through the central hole 701 and the vertical channel 702.

[0024] Compared to traditional inert gas protection systems, this invention utilizes a dividing cylinder 7 and a hydraulic cylinder 10. During the gas injection and sealing stage, the dividing cylinder 7 and the gas injection pipe 4 work together to lift the seawater above the tower body 3, causing the seawater below the dividing cylinder 7 to form a water seal on the gas injection pipe 4. This reduces the water seal depth of the gas injection pipe 4, thereby reducing the back pressure that the blower 2 needs to overcome when delivering inert gas, thus reducing the working power of the blower 2 during gas injection. This achieves energy saving and consumption reduction during gas injection and sealing. During static sealing, the water seal effect is further improved by increasing the water seal depth. In addition, through the vertical channel 702 opened in the shell wall of the dividing cylinder 7, after the central hole 701 is blocked, the airflow flows through the vertical channel 702, realizing the flow of inert gas.

[0025] Please see Figure 1 and Figure 2 The tower body 3 has a cylindrical structure, the air injection pipe 4 is inverted L-shaped and its lower part is located at the central axis of the tower body 3. Above the mounting ring 11, there is a demister 6 that is fixedly connected to the inner wall of the tower body 3. The center of the demister 6 has a through hole for the air injection pipe 4 to pass through.

[0026] Specifically, the inert gas flows upward after passing through sealed seawater and passes through demister 6 to remove tiny droplets from the gas. Demister 6 is a baffle-type demister, which is existing technology and will not be described in detail in this application.

[0027] Please see Figure 2 and Figure 3 The dividing cylinder 7 has a cylindrical structure with an open top. An inner sealing sleeve 8 is fixedly connected to the inner wall of the central hole 701. The inner sealing sleeve 8 is used to fill the contact gap between the central hole 701 and the gas injection pipe 4. An outer sealing sleeve 9 is fixedly connected to the circumferential side wall of the dividing cylinder 7. The outer sealing sleeve 9 slides against the inner wall of the tower body 3.

[0028] Specifically, the inner sealing sleeve 8 and the outer sealing sleeve 9 enable the dividing cylinder 7 to have a better isolation and sealing effect.

[0029] In this embodiment, both the inner sealing sleeve 8 and the outer sealing sleeve 9 are made of rubber material. The outer edge of the lower opening of the air injection tube 4 is provided with a rounded corner surface, and the inner edge of the upper opening of the inner sealing sleeve 8 is provided with a rounded corner surface.

[0030] Specifically, this facilitates the smooth insertion of the dividing cylinder 7 into the outer side of the air injection pipe 4 when it moves upward, and allows the gap between the center hole 701 and the air injection pipe 4 to be quickly sealed.

[0031] Please see Figure 2The water inlet pipe 12 is an inverted U-shaped pipe. The height of the connection between the water inlet pipe 12 and the tower body 3 is lower than the height of the lower end face of the dividing cylinder 7 at the lowest point. A seawater pump is fixedly connected to the end of the water inlet pipe 12 away from the tower body 3. The seawater pump injects seawater into the tower body 3 through the water inlet pipe 12. A vent valve 14 is fixedly connected to the center of the top of the water inlet pipe 12. The vent valve 14 is used to balance the pressure inside the tower body 3.

[0032] Specifically, when the seawater pump switches from working to stopped, the seawater remaining in the inlet pipe 12 is prone to backflow to the pump side under gravity, which causes negative pressure in the inlet pipe 12 and creates a siphon effect, causing the seawater injected into the tower body 3 to be drawn out and unable to form a water seal. However, when the vent valve 14 is provided, external airflow is injected into the inlet pipe 12 to balance the pressure and prevents the siphon phenomenon. In addition, during the rising process of the dividing cylinder 7, the vent valve 14 is used to balance the pressure in the cavity below the dividing cylinder 7, so that a cavity for storing air is formed between the lower end face of the dividing cylinder 7 and the seawater surface below.

[0033] Please see Figure 2 The height of the connection between the overflow pipe 13 and the tower body 3 is lower than the height of the lower end face of the dividing cylinder 7 when it is at its lowest point, and the height of the upper opening of the overflow pipe 13 is lower than the height of the lower end face of the demister 6.

[0034] Specifically, during static sealing, the overflow pipe 13 is sealed by seawater, preventing inert gases and petroleum volatiles from overflowing through the overflow pipe 13. Furthermore, the height of the water seal liquid level is controlled during static sealing to prevent seawater from entering the demister 6 and the exhaust pipe 5.

[0035] Please see Figure 2 A liquid level sensor 15 is fixedly connected to the lower end face of the mounting ring 11. The liquid level sensor 15 is used to detect the seawater level in the tower body 3 during static sealing. A liquid level sensor 26 is fixedly connected to the lower end face of the dividing cylinder 7. The liquid level sensor 26 is used to detect the seawater level below the dividing cylinder 7 during gas injection sealing.

[0036] Specifically, both liquid level sensor 15 and liquid level sensor 16 are ultrasonic liquid level sensors, and both are electrically connected to the same controller. The controller is connected to an audible and visual alarm, which will promptly alarm when the liquid level does not meet the set value. Alarming by monitoring the liquid level is existing technology and will not be described in detail in this application.

[0037] Second implementation method Based on the first implementation, please refer to Figure 2 , Figure 6 and Figure 7The hydraulic cylinder 10 includes a cylinder body 17 fixedly connected to the mounting ring 11. A piston rod 18 is slidably connected inside the cylinder body 17. The lower end of the piston rod 18 is fixedly connected to the bottom plate of the dividing cylinder 7. A piston disc 19 is fixedly connected to the upper end of the piston rod 18. The piston disc 19 slides against the inner wall of the cylinder body 17. A safety tube 21 is fixedly connected to the outer wall of the cylinder body 17. The safety tube 21 is used to connect the cavities of the cylinder body 17 located on both sides of the piston disc 19. A normally open solenoid valve 22 is fixedly connected to the safety tube 21. The normally open solenoid valve 22 is used to make the safety tube 21 open when the power is off.

[0038] Specifically, during gas injection, if the equipment experiences a sudden power outage, please refer to [the relevant documentation / guideline]. Figure 8 Normally open solenoid valve 22 (closed when conductive) is in the conducting state. At this time, the hydraulic oil on both sides of the cylinder 17 is connected through safety pipe 21. The dividing cylinder 7 moves downward under its own weight and the weight of the seawater above. The piston rod 18 drives the piston disc 19 to move downward in the cylinder 17, so that the dividing cylinder 7 can move to below the lower opening of the air injection pipe 4 and automatically restore to the water seal depth required for static sealing, thereby improving the safety and water seal effect of the water seal tower 1 after power failure.

[0039] It should be noted that a pair of symmetrically arranged oil inlet pipes 20 are also fixedly connected to the cylinder body 17. The outer ends of the pair of oil inlet pipes 20 are respectively connected to the same reversing valve through pipes. The reversing valve is connected to the oil pump and the oil reservoir in sequence through pipes. The drive structure of the hydraulic cylinder 10 is the prior art, and will not be described in detail in this application.

[0040] The above description is merely a preferred embodiment of the present invention; however, the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and its improved concept, should be covered within the scope of protection of the present invention.

Claims

1. An inert gas explosion-proof protection system for a very large crude carrier (VLCC), characterized in that, The system includes a water-sealed tower (1), which includes a tower body (3). The top wall of the tower body (3) is fixedly connected to an injection pipe (4) extending to the lower part of its inner cavity. The upper end of the tower body (3) is fixedly connected to an exhaust pipe (5) communicating with its inner cavity. The tower body (3) is filled with sealed seawater with a liquid level higher than the opening height of the lower end of the injection pipe (4). The upper end of the injection pipe (4) is fixedly connected to the outlet of a blower (2). The inlet of the blower (2) is connected to the outlet of a scrubbing tower. The inlet of the scrubbing tower is connected to the outlet of an inert gas generator. The outer end of the exhaust pipe (5) is connected to the inner cavity of each cargo oil tank through a distribution pipe. Below the gas injection pipe (4) is a dividing cylinder (7) that is slidably connected to the inner wall of the tower body (3). The center of the bottom of the dividing cylinder (7) is provided with a central hole (701) through which the gas injection pipe (4) passes, and multiple evenly distributed vertical channels (702) are provided in its circumferential side wall. The central hole (701) and the vertical channels (702) are used to connect the cavities located on both sides of the dividing cylinder (7) in the tower body (3). The dividing cylinder (7) is fixedly connected to the movable end of a pair of hydraulic cylinders (10). The fixed end of the hydraulic cylinder (10) is fixedly connected to an installation ring (11). The installation ring (11) is fixedly connected to the inner wall of the tower body (3). The hydraulic cylinder (10) is used to drive the dividing cylinder (7) to move upward in the tower body (3). The side wall of the tower body (3) is fixedly connected to a water inlet pipe (12) and an overflow pipe (13).

2. The inert gas explosion-proof protection system for a very large crude carrier (VLCC) according to claim 1, characterized in that, The tower body (3) has a cylindrical structure, the air injection pipe (4) is inverted L-shaped and its lower part is located at the central axis of the tower body (3), and a demister (6) is fixedly connected to the inner wall of the tower body (3) above the mounting ring (11). A through hole for the air injection pipe (4) to pass through is opened at the center of the demister (6).

3. The inert gas explosion-proof protection system for a very large crude carrier (VLCC) according to claim 1, characterized in that, The dividing cylinder (7) has a cylindrical structure with an open top. An inner sealing sleeve (8) is fixedly connected to the inner wall of the central hole (701). The inner sealing sleeve (8) is used to fill the contact gap between the central hole (701) and the gas injection pipe (4). An outer sealing sleeve (9) is fixedly connected to the circumferential side wall of the dividing cylinder (7). The outer sealing sleeve (9) slides against the inner wall of the tower body (3).

4. The inert gas explosion-proof protection system for a very large crude carrier (VLCC) according to claim 3, characterized in that, Both the inner sealing sleeve (8) and the outer sealing sleeve (9) are made of rubber material. The outer edge of the lower opening of the air injection pipe (4) is provided with a rounded corner surface, and the inner edge of the upper opening of the inner sealing sleeve (8) is provided with a rounded corner surface.

5. The inert gas explosion-proof protection system for a very large crude carrier (VLCC) according to claim 1, characterized in that, The water inlet pipe (12) is an inverted U-shaped pipe. The height of the connection between the water inlet pipe (12) and the tower body (3) is lower than the height of the lower end face of the dividing cylinder (7) at the lowest point. A seawater pump is fixedly connected to one end of the water inlet pipe (12) away from the tower body (3). The seawater pump injects seawater into the tower body (3) through the water inlet pipe (12). A vent valve (14) is fixedly connected to the center of the top of the water inlet pipe (12). The vent valve (14) is used to balance the pressure inside the tower body (3).

6. The inert gas explosion-proof protection system for a very large crude carrier (VLCC) according to claim 1, characterized in that, The height of the connection between the overflow pipe (13) and the tower body (3) is lower than the height of the lower end face of the dividing cylinder (7) when it is at its lowest point, and the height of the upper opening of the overflow pipe (13) is lower than the height of the lower end face of the demister (6).

7. The inert gas explosion-proof protection system for a very large crude carrier (VLCC) according to claim 1, characterized in that, A liquid level sensor (15) is fixedly connected to the lower end face of the mounting ring (11). The liquid level sensor (15) is used to detect the height of the seawater in the tower body (3) during static sealing. A liquid level sensor (16) is fixedly connected to the lower end face of the dividing cylinder (7). The liquid level sensor (16) is used to detect the height of the seawater below the dividing cylinder (7) during gas injection sealing.

8. The inert gas explosion-proof protection system for a very large crude carrier (VLCC) according to claim 1, characterized in that, The hydraulic cylinder (10) includes a cylinder body (17) fixedly connected to the mounting ring (11). A piston rod (18) is slidably connected inside the cylinder body (17). The lower end of the piston rod (18) is fixedly connected to the bottom plate of the dividing cylinder (7). A piston disc (19) is fixedly connected to the upper end of the piston rod (18). The piston disc (19) slides against the inner wall of the cylinder body (17). A safety tube (21) is fixedly connected to the outer wall of the cylinder body (17). The safety tube (21) is used to connect the cavities of the cylinder body (17) located on both sides of the piston disc (19). A normally open solenoid valve (22) is fixedly connected to the safety tube (21). The normally open solenoid valve (22) is used to make the safety tube (21) open when the power is off.

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